LINAC2014 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOIOB01	Early Commissioning Experience and Future Plans for the 12 GeV Continuous Electron Beam Accelerator Facility	cryomodule, linac, operation, SRF	11
	M. Spata JLab, Newport News, Virginia, USA
	Jefferson Lab has recently completed the accelerator portion of the 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility. All 52 SRF cryomodules have been commissioned and operated with beam. The initial beam transport goals of demonstrating 2.2 GeV per pass, greater than 6 GeV in 3 passes to an existing experimental facility and greater than 10 GeV in 5-1/2 passes have all been accomplished. These results along with future plans to commission the remaining beamlines and to increase the performance of the accelerator to achieve reliable, robust and efficient operations at 12 GeV are presented.
	Slides MOIOB01 [2.754 MB]

MOIOC01	Status of Superconducting Electron Linac Driver for Rare Ion Beam Production at TRIUMF	cryomodule, linac, electron, TRIUMF	31
	R.E. Laxdal, F. Ames, R.A. Baartman, I.V. Bylinskii, Y.-C. Chao, D. Dale, K. Fong, E.R. Guetre, P. Kolb, S.R. Koscielniak, A. Koveshnikov, M.P. Laverty, Y. Ma, M. Marchetto, L. Merminga, A.K. Mitra, N. Muller, R.R. Nagimov, T. Planche, W.R. Rawnsley, V.A. Verzilov, Z.Y. Yao, Q. Zheng, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	A MW class cw superconducting electron linac is being installed at TRIUMF as a driver for radioactive beam production through photo-fission. The ARIEL e-linac will house five 1.3GHz nine-cell cavities in three cryomodules and accelerate up to 10mA of electrons to 50MeV. A first phase of installation will see three cavities in two cryomodules installed by the end of 2014. Presently the injector cryomodule is installed and undergoing cryogenic and rf characterizations and beam acceleration tests with beam from the 300kV DC gun. The second cryomodule is being prepared for first tests. The linac status including descriptions and operating performance of installed cryogenic and rf systems, electron gun performance, cryomodule performance and the results of first beam acceleration tests will be reported.
	Slides MOIOC01 [6.383 MB]

MOIOC03	Model and Beam Based Setup Procedures for a High Power Hadron Superconducting Linac	linac, simulation, laser, quadrupole	41
	A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	This presentation will review methods for experimental determination of optimal operational set points in a multi-cavity superconducting high power hadron linac. A typical tuning process, including establishing correct acceleration profile and RMS bunch size matching, is based on comparison between measured data and the results of simulations from envelope, single and multi-particle models. Presence of significant space charge effects requires simulation and measurement of bunch dynamics in 3 dimensions to ensure low loss beam transport. This is especially difficult in a superconducting linac where use of interceptive diagnostics is usually restricted because of the risk of SRF cavity surface contamination. The procedures discussed here are based on non-interceptive diagnostics such as beam position monitors and laser wires, and conventional diagnostics devices such as wire scanners and bunch shape monitors installed outside the superconducting linac. The longitudinal Twiss analysis based on the BPM signals will be described. The superconducting SNS linac tuning experience will be used to demonstrate problems and their solution for real world linac tune-up procedures.
	Slides MOIOC03 [1.954 MB]

MOPP001	First Experimental Results for the Superconducting Half-Wave Resonators for PXIE	niobium, proton, cryomodule, accelerating-gradient	46
	Z.A. Conway, A. Barcikowski, G.L. Cherry, R.L. Fischer, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, T. Reid, K.W. Shepard ANL, Argonne, Illinois, USA
	Funding: This work was supported by the U.S. Department of energy, Offices of High-Energy Physics and Nuclear Physics, under Contract No. DE-AC02-76-CH03000 and DE-AC02-06CH11357. The first pair of superconducting niobium half-wave resonators operating at 162.5 MHz for the FNAL PIP-II project are complete and this poster reports the cold test results. These cavities are optimized to accelerate protons/H⁻ from 2 to 10 MeV and build upon optimized electromagnetic designs and processing techniques developed at Argonne for the Intensity Upgrade of the ATLAS superconducting heavy ion accelerator.

MOPP002	Design of a Superconducting Quarter-Wave Resonator for eRHIC	electron, linac, SRF, niobium	49
	S.V. Kutsaev, Z.A. Conway, M.P. Kelly, B. Mustapha, P.N. Ostroumov ANL, Argonne, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA S.A. Belomestnykh, I. Ben-Zvi, Q. Wu, W. Xu BNL, Upton, Long Island, New York, USA B. P. Xiao SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.

MOPP003	A Compact Linac Design for an Accelerator Driven System	linac, cryomodule, lattice, focusing	52
	B. Mustapha, S.V. Kutsaev, J.A. Nolen, P.N. Ostroumov ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. A compact linac design has been developed for an Accelerator Driven System (ADS). The linac is under 150 meters in length and comprises a radio-frequency quadrupole (RFQ) and 20 superconducting modules. Three types of half-wave cavities and two types of elliptical cavities have been designed and optimized for high performance at frequencies of 162.5, 325 and 650 MHz. The lattice is being designed and optimized for operation with a peak power of 25 MW for a 25 mA – 1 GeV proton beam. The cavities RF design as well as the linac lattice will be presented along with end-to-end beam dynamics simulations for beam currents ranging from 0 to 25 mA.

MOPP012	Beam Commissioning of the SRF 704 MHz Photoemission Gun	cathode, gun, SRF, electron	70
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, G.T. McIntyre, D. Phillips, V. Ptitsyn, K.S. Smith, R. Than, D. Weiss, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Ptitsyn Stony Brook University, Stony Brook, USA D. Holmes AES, Medford, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under comissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert it reached 1.9 MV with 18% duty factor, which is limited by mulitpacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. This paper presents recent commissioning results, including cavity commissioning without the cathode stalk insert, first beam commissioning of the SRF gun in pulsed regime, and the design of a multipacting-free cathode stalk.

MOPP013	Vertical Test Results of 704 MHz BNL3 SRF Cavities	HOM, SRF, electron, damping	73
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, R. Porgueddu, R. Than, D. Weiss BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA M.D. Cole, D. Holmes, T. Schultheiss AES, Medford, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE, and Award No. DE-SC0002496 to Stony Brook University with the U.S. DOE. An electron-ion collider (eRHIC) proposed at BNL requires superconducting RF cavities able to support high average beam current. A 5-cell niobium SRF cavity, called BNL3, was designed for a conventional lattice eRHIC design. To avoid inducing emittance degradation and beam-break-up (BBU), the BNL3 cavity was optimized to damp all dangerous higher-order-modes (HOMs) by employing a large beam pipes and coaxial antenna-type couplers. Additionally, the cavity was designed for an acceptable cryogenic load and peak surface RF fields. Two BNL3 cavities have been fabricated and tested at a vertical test facility at BNL. This paper addresses development of the SRF cavities for eRHIC, including SRF cavity design, fabrication and test results.

MOPP016	Extracting Superconducting Parameters from Surface Resistivity by Using Inside Temperature of SRF Cavities	accelerating-gradient, SRF, electron, superconductivity	80
	G.M. Ge, G.H. Hoffstaetter, M. Liepe, H. Padamsee, V.D. Shemelin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The surface resistance of an RF superconductor depends on the surface temperature, the residual resistance and various superconductor parameters. These parameters can be determined by measuring the quality factor of a SRF cavity in helium-baths of different temperatures. The surface resistance can be computed from Q0 for any cavity geometry, however it is less simple to determine the temperature of the surface when only the temperature of the helium bath is known. Traditionally, it was approximated that the surface temperature on the inner surface of the cavity is the same as the temperature of the bath. This is a good approximation at small RF-field losses on the surface, but to determine the field dependence of Rs, one cannot be restricted to small field losses. Here we show how computer simulations can be used to determine the inside temperature so that Rs(Tin) can then be used to extract superconductor parameters. The computer code combines the well-known programs HEAT and SRIMP. We find that the error of the incorrect fitting method is about 10% at high RF-fields.

MOPP017	Cool Down and Flux Trapping Studies on SRF Cavities	SRF, cryomodule, linac, operation	84
	D. Gonnella, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Recent results from Cornell and FNAL have shown that cool down rate can have a strong impact on the residual resistance of a superconducting RF cavity during operation. We have studied the effect of cool down rate, gradient, and external magnetic field during cool down on the residual resistance of an EP, EP+120C baked, and nitrogen-doped cavities. For each cavity, faster cool down and large gradient resulted in lower residual resistance in vertical test. The nitrogen-doped cavities showed the largest improvement with fast cool down, while the EP+120C cavity showed the smallest. The cavities were also placed in a uniform external magnetic field and residual resistance was measured as a function of applied field and cool down rate. We show that the nitrogen-doped cavity was the most susceptible to losses from trapped flux and the EP+120C cavity was least susceptible. These measurements provide new insights into understanding the physics behind the observed impact of cool down rates and gradients on the performance of cavities with differing preparations.

MOPP018	Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule	cryomodule, SRF, radiation, linac	88
	D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Grassellino, A. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP019	Nb3Sn Materials Studies	niobium, SRF, electron, ion	92
	S. Posen, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA Th. Proslier ANL, Argonne, Illinois, USA
	Nb₃Sn is a very promising material for use in SRF cavity applications, potentially offering significant improvements in quality factor and energy gradient compared to niobium. In order to better understand how to optimize this material for SRF applications, Nb₃Sn samples were prepared at Cornell via vapor deposition, using varying parameters in the coating process. Microscopic studies were performed with SEM/EDX, and studies were performed on bulk samples to measure secondary electron yield, energy gap, and upper critical magnetic field. The results are presented here, with discussion for how they might point the way towards reaching even higher fields in Nb₃Sn cavities.
	Poster MOPP019 [2.742 MB]

MOPP020	Input Couplers for Cornell ERL	linac, cryomodule, coupling, impedance	95
	R.G. Eichhorn, P. Quigley, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S.A. Belomestnykh BNL, Upton, Long Island, New York, USA
	Cornell has developed two types of input couplers for the Energy Recovery Linac (ERL) Project. Both couplers are 1.3 GHz CW coaxial couplers. The coupler for ERL injector is a 65 kW CW coupler with variable coupling (Qext = 9E4 to 9E5). The coupler for ERL main linac is a 5 kW CW coupler with fixed coupling. It can be easily modified for variable coupling operation. Couplers have been tested on test stands and in cryomodules and showed good performance.

MOPP025	Longitudinal Beam Profile Measurements in Linac4 Commissioning	rfq, linac, electron, emittance	108
	G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca CERN, Geneva, Switzerland M. Yarmohammadi Satri IPM, Tehran, Iran
	Linac4, the future 160 MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.

MOPP026	Actively Cooled RF Power Coupler : Theoretical and Experimental Studies	cryomodule, cryogenics, proton, linac	111
	R. Bonomi, V. Parma CERN, Geneva, Switzerland
	In cryostats for Super-conducting Radio Frequency Cavities, the heat loads introduced by the high-power RF couplers represent an important fraction of the overall static thermal budget. Working at low operating temperature benefits from a reduced surface resistance (low dynamic losses) but is penalized by the high refrigeration cost. The external conductor of RF coaxial couplers provides a direct conduction path from ambient to cryogenic temperature plus is heated by resistive power deposition. Heat interception is therefore essential to contain heat in-leaks: a double-walled external conductor with a properly designed gas cooling effectively reduces heat loads to the cold bath by 1 order of magnitude. This paper presents the thermal design of the RF power coupler of the Superconducting Proton Linac (SPL) at CERN, featuring a helium vapour cooling between 4.5 K and ambient temperature. Numerical models, which can be used as design tools for other applications, have been developed to assess efficiency and thermal performance. A full-size mock-up cooled by nitrogen has been built for experimental validation. Comparison between calculations and measurements is presented and discussed.

MOPP029	Overview of the New High Level Software Applications Developed for the HIE-ISOLDE Superconducting Linac	controls, linac, software, pick-up	117
	D. Lanaia, M.A. Fraser, D. Voulot CERN, Geneva, Switzerland
	The High Intensity and Energy (HIE) ISOLDE project consists of an upgrade of the ISOLDE facility. With the installation of 32 independently-phased, superconducting quarter-wave cavities the energy of post-accelerated radioactive beams will be increased from 3 MeV/u to over 10 MeV/u. The large number of cavities will increase the number of parameters to optimise. In order to ensure a fast set-up of the machine during operation and commissioning, new software applications have been developed and an upgrade of the existing software was carried out. Four high level applications have been specifically developed for the SC linac. The first allows the conversion of optics settings into machine settings, and vice versa. The second will aid the phasing of the cavities using beam energy measurements. A third application will provide absolute measurements of the beam energy by means of a time-of-flight system. The last application will automatically generate the phase and voltage settings for the cavities SC linac. In this contribution we will present the new applications and outline how these will be used in the operation of the new SC linac.
	Poster MOPP029 [1.568 MB]

MOPP034	Beam Dynamics Studies of the CLIC Drive Beam Injector	bunching, emittance, focusing, quadrupole	131
	S. Sanaye Hajari, S. Döbert, H. Shaker CERN, Geneva, Switzerland S. Sanaye Hajari, H. Shaker IPM, Tehran, Iran
	In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel with the main linac. The beam in the Drive Beam Accelerator is phase coded. This means only every second accelerator bucket is occupied. However, a few percent of particles are captured in wrong buckets, called satellite bunches. The phase coding is done via a sub-harmonic bunching system operating at a half the acceleration frequency. The beam dynamics of the Drive Beam injector complex has been studied in detail and optimised. The model consists of a thermionic gun, the bunching system followed by some accelerating structures and a magnetic chicane. The bunching system contains three sub-harmonic bunchers, a prebuncher and a tapered travelling wave buncher all embedded in a solenoidal magnetic field. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimising the overall bunching process and in particular decreasing the satellite population and the beam loss in magnetic chicane and in transverse plane limiting the beam emittance growth.

MOPP035	Bead-Pull Measurement Method and Tuning of a Prototype CLIC Crab Cavity	electromagnetic-fields, coupling, simulation, extraction	134
	R. Wegner, W. Wuensch CERN, Geneva, Switzerland G. Burt, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	A bead-pull method has been developed which measures in a single bead passage the amplitude and phase advance of deflecting mode travelling wave structures. This bead-pull method has been applied to measure and tune a Lancaster University-designed prototype crab cavity for CLIC. The technique and tuning results are described.

MOPP037	Conceptual Design of the ESS DTL Faraday Cup	DTL, simulation, linac, beam-transport	140
	B. Cheymol, E. Lundh ESS, Lund, Sweden
	The DTL section of the ESS linac will accelerate the beam form 3.6 MeV to 90 MeV at a peak current of 62.5 mA. It is foreseen to install after each DTL tank a Faraday cup for beam current and the beam transmission measurements during retuning phase. An energy degrader will be positioned in front of the in order to perform a low resolution phase scan of the DTL tank before injecting the beam in the downstream structure. This paper describes the preliminary studies of the Faraday cup, mainly focus on the energy degrader.

MOPP040	Application Investigation of High Precision Measurement for Basic Cavity Parameters at ESS	controls, operation, beam-loading, injection	149
	R. Zeng ESS, Lund, Sweden P. Jonsson Lund University, Lund, Sweden W. Schappert Fermilab, Batavia, Illinois, USA
	The ESS cavity control and operation methods/algorithms are challenging due to the use of long pulse, higher beam intensity, high beam power, high gradient, uncertainties in spoke cavities and high demands for energy efficiency and availability. Suitable and effective solutions could make use of modern technologies (flexible FPGA, faster CPU, bigger memory, faster communication speed), novel measuring techniques, accurate system modeling, and advanced control concept. Those possible implementations are essential to a better understanding, and thus a better operation of ESS cavity especially SRF cavities. All these concepts rely on high precision measurement of basic cavity parameters and consequent high quality data with high resolution, high precision and completeness. This paper focuses on how high precision measurement will address the challenges at ESS on the following topics: long pulse lorentz force detuning, high precision phase and amplitude setting, heavy beam loading compensation and power overhead reduction.

MOPP044	MSU RE-Accelerator ReA3 0.085 QWR Cryomodule Status	cryomodule, solenoid, alignment, linac	155
	T. Xu, B. Bird, F. Casagrande, J.L. Crisp, K.D. Davidson, C. Dudley, A. Facco, P.E. Gibson, I. Grender, L. Hodges, K. Holland, M.J. Johnson, S. Jones, B. Laumer, D. Leitner, A. Mccartney, S.J. Miller, D. Morris, S. Nash, J.P. Ozelis, J. Popielarski, L. Popielarski, R. Rosas, R.J. Rose, K. Saito, M. Thrush, R. Walker, J. Wei, W. Wittmer, Y. Xu FRIB, East Lansing, Michigan, USA B. Arend, J. Ottarson, D.P. Sanderson, D. Wahlquist, J. Wenstrom NSCL, East Lansing, Michigan, USA M. Leitner LBNL, Berkeley, California, USA
	ReA3 β=0.085 QWR cryomodule is the third cryomodule for the superconducting LINAC of ReA3 reaccelerated beam facility, which will bring the maximum beam energy to 3 MeV/u for heavy ions. This cryomodule consists of 8 β=0.085 QWR cavities and 3 9T superconducting solenoids and operates at 4K. Qualification of cavities and FPCs and the construction of cold mass was completed in 2013. The installation of the module was completed this summer. Functioning not only as an important part of the ReA3 facility, cryomodule 3 also serves as a test bed for FRIB driver Linac and demonstrated the technology needed for FRIB CMs. Here we report the construction, installation and testing of the β=0.085 cryomodule and the development of the critical components. Project funded by Michigan State University

MOPP046	On the Design of Higher Order Mode Antenna for LCLS II	HOM, coupling, higher-order-mode, simulation	161
	M.H. Awida, I.V. Gonin, T.N. Khabiboulline, K.S. Premo, O.V. Pronitchev, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE The upgrade of the Linac Coherent Light Source (LCLS-II) necessitates a major modification to the higher order mode (HOM) antenna of the conventional ILC elliptical 9-cell cavity. Due to the continuous wave nature of the proposed LCLS II Linac, the HOM antenna is required to bare higher RF losses. A modified design of the HOM antenna is presented in this paper ahead with a thorough thermal quench study in comparison with the conventional ILC design.

MOPP049	Dipole Kick due to Geometry Asymmetries in HWR for PXIE	dipole, multipole, linac, cryomodule	165
	P. Berrutti, T.N. Khabiboulline, V.A. Lebedev, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by D.O.E. Contract No. DE-AC02-07CH11359 Project X Injector Experiment (PXIE) will have a family of half wave resonators having frequency=162.5 MHz and beta optimal=0.11. During cavity production, when the niobium parts are assembled and welded together, it is fundamental to control the frequency of the accelerating mode in order to meet the specified operating value. For the HWR of PXIE the tuning will be achieved by trimming one end of the resonator only, this will introduce unwanted asymmetry in the cavity geometry leading to a dipole kick for the particles traveling through the cavity. The cavity geometry will be different from the ideal, once the cavity is assembled, because of small misalignment of the niobium parts and because of the welding shrinkage. Misalignments of the inner conductor and the beam pipes can be expected. The asymmetry due to tuning process along with production misalignments, have been simulated and the equivalent dipole kick has been calculated.
	Poster MOPP049 [1.441 MB]

MOPP052	Development of 5-Cell β=0.9 650 MHz Elliptical Cavities for Project X	linac, HOM, coupling, accelerating-gradient	171
	I.V. Gonin, M.H. Awida, M.H. Foley, A. Grassellino, C.J. Grimm, T.N. Khabiboulline, A. Lunin, A.M. Rowe, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Several 5-cell 650 MHz elliptical cavities have been fabricated for the PIP-II Project. Two versions of the cavities have been designed to accelerate protons of relative group velocity of β=0.9 and β=0.92 in the high energy region of the linac. In this paper, we report the development status of these cavities, summarize the results of the quality control measurements performed on five initial prototypes, and outline the VTS test results.

MOPP054	Continuous-Wave Horizontal Tests of Dressed 1.3 GHz SRF Cavities for LCLS-II	HOM, controls, SRF, linac	177
	A. Hocker, A.C. Crawford, M. Geynisman, J.P. Holzbauer, A. Lunin, D.A. Sergatskov, N. Solyak, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359 Fermilab’s Horizontal Test Stand has recently been upgraded to provide CW RF testing capabilities in support of the LCLS-II project at SLAC. Several cavities have been tested in this new configuration in order to validate component designs and processes for meeting the requirements of LCLS-II. Areas of study included gradient and Q0 performance and their dependence on extrinsic factors, thermal performance of the input coupler and HOM feedthroughs, and microphonics and RF control. A description of the testing and the results obtained are presented.
	Poster MOPP054 [0.276 MB]

MOPP055	RF Tests of Dressed 325 MHz Single-Spoke Resonators at 2 K	network, operation, LLRF, resonance	180
	A. Hocker, E. Cullerton, B.M. Hanna, W. Schappert, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	Funding: United States Department of Energy, Contract No.DE- AC02-07CH11359 Fermilab has recently completed an upgrade to its spoke resonator test cryostat to enable testing of cavities in superfluid helium. Two single-spoke resonators with differing helium vessel designs have been tested in this new configuration. Gradient and Q0 performance was studied along with microphonics control and sensitivity of the resonant frequency to pressure variations. A description of the testing and the results obtained are presented.
	Poster MOPP055 [0.437 MB]

MOPP058	Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac	electron, laser, radiation, dipole	183
	J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA W.B. Wortley University of Rochester, Rochester, New York, USA
	Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP059	Study and Design of the High Power RF Coupler for the CH-Cavity of the Fair pLINAC	coupling, proton, linac, resonance	187
	F. Maimone, G. Clemente, W. Vinzenz GSI, Darmstadt, Germany
	At GSI a proton Linac has been designed and developed in order to provide a 70 MeV proton beam for the FAIR facility. The pLINAC consists of an RFQ followed by six CH-DTL accelerating cavities and the electromagnetic field inside each cavity is generated by seven Klystrons providing up to 2.8 MW power at 325.224 MHz. The high power RF coupling between the Klystron and the accelerating CH-cavity has been studied and an inductive coupling loop has been designed. The coupler insertion inside the cavity and the rotation angle with respect to the magnetic field lines have been adjusted and the results of the analysis of the coupler positioning are presented. A prototype coupler is under construction and the measurement of RF coupling with the CH-cavity is scheduled within this year.

MOPP061	First RF Measurements of the Superconducting 217 MHz CH Cavity for the CW Demonstrator at GSI	simulation, linac, status, ion	193
	F.D. Dziuba, M. Amberg, M. Basten, M. Busch, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher, W.A. Barth, S. Mickat HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: Work supported by GSI, HIM, BMBF Contr. No. 05P12RFRBL Presently, a superconducting (sc) 217 MHz Crossbar-Hmode (CH) cavity is under construction at Research Instruments (RI), Bergisch Gladbach, Germany. Among the horizontal cryomodule and two sc 9.5 T solenoids the cavity is the key component of the cw demonstrator at GSI. To show the operation ability of sc CH cavity technology under a realistic linear accelerator environment is one major goal of the demonstrator project. A successful beam operation of the demonstrator will be a milestone regarding the continuing advanced sc cw linac project at GSI for a competitive production of Super Heavy Elements (SHE) in the future. The fabrication status as well as first rf measurements at room temperature of the 217 MHz CH cavity are presented.
	Poster MOPP061 [1.741 MB]

MOPP062	Proposal of a Conventional Matching Section as an Alternative to the Existing HSI MEBT Superlens at GSI UNILAC	DTL, simulation, rfq, emittance	196
	H. Hähnel, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	We propose a new design for the HSI MEBT section at GSI UNILAC as part of the planned UNILAC upgrade. The existing MEBT section was designed in 1996 and based on a novel concept called the superlens* which uses a magnetic quadrupol doublet lens combined with a short RFQ cavity for transversal and longitudinal focusing. In 2009 the RFQ section in front of the MEBT was upgraded which led to significant changes in the RFQ output particle distribution. Recent LORASR simulations show that the superlens transmission decreases to 90% (related to 20.75 mA, U⁴⁺ at input). Moreover, the matching to the following IH-DTL is not ideal. This leads to further losses in the IH and to a decrease of the overall UNILAC efficiency. To reach the FAIR requirement of 18 mA U⁴⁺ current for the UNILAC with minimal losses and to provide more flexibility for varying current level operation, a new design based on two magnetic quadrupole triplet lenses and a 2-gap buncher is proposed. The design shows full transmission at 20.75 mA U⁴⁺ current and improved matching to the IH-DTL, leading to a drastic decrease of particle losses along the IH-DTL. * U. Ratzinger, R. Tiede, A New Matcher Type between RFQ and IH-DTL for the GSI High Current Heavy Ion Prestripper LINAC, Proc. LINAC96, Geneva, Switzerland, pp. 128-130
	Poster MOPP062 [9.440 MB]

MOPP064	R&D of the 17 MeV MYRRHA Injector	emittance, proton, rfq, linac	202
	D. Mäder, M. Basten, D. Koser, H.C. Lenz, N.F. Petry, H. Podlech, A. Schempp, M. Schwarz, M. Vossberg IAP, Frankfurt am Main, Germany C. Zhang GSI, Darmstadt, Germany
	Funding: Project supported by the EU, FP7 MAX, Contract No. 269565 MYRRHA is designed as an accelerator driven system (ADS) for transmutation of long-lived radioactive waste. The challenge of the linac development is the very high reliability of the accelerator to limit the thermal stress inside the reactor. With the concept of parallel redundancy the injector will supply a cw proton beam with 4 mA and 17 MeV to the main linac. The new MYRRHA injector layout consists of a very robust beam dynamics design with low emittance growth rates. Sufficient drift space provides plenty room for diagnostic elements and increases the mountability. Behind a 4-Rod-RFQ and a pair of two-gap QWR rebunchers at 1.5 MeV the protons are matched into the CH cavity section. A focussing triplet between the rebunchers ensures an ideal transversal matching into the doublet lattice. Each of the 7 RT CH structures has a constant phase profile and does not exceed thermal losses of 29 kW/m. The transition to the 5 SC CH cavities with constant beta profile is at 5.9 MeV. For a safe operation of the niobium resonators the electric and magnetic peak fields are defined below 25 MV/m and 57 mT respectively.
	Poster MOPP064 [4.024 MB]

MOPP066	High Gradient CH-Type Cavity Development for 10 – 100 AMeV Beams	linac, quadrupole, ion, heavy-ion	208
	A. Almomani, U. Ratzinger IAP, Frankfurt am Main, Germany
	Funding: This work is supported by Federal Ministry of Education and Research - BMBF No. 05P12RFRB9. The development in pulsed linac activities aims on compact designs and on an increase of the voltage gain per meter. At IAP - Frankfurt, a CH design was developed for these studies, where the mean effective accelerating field is expected to reach well above 10 MV/m at 325 MHz, β=0.164. Within a funded project, this cavity is systematically developed. Currently, the cavity is under construction at NTG GmbH and expected to be ready for copper plating in autumn 2014. The results should give an impact on the rebuilt of the UNILAC - Alvarez section, optimized for achieving the beam intensities specified for the GSI – FAIR project. A mid- and long- term aim is a compact pulsed high current linac. The new GSI 3 MW Thales klystron test stand will be very important for these investigations. Detailed studies on two different types of copper plating can be performed on this cavity. Additionally, operating of normal conducting cavities at cryogenic temperatures will be discussed. In this work, the cavity status will be presented.

MOPP068	The Fast Piezo-Based Frequency Tuner for SC CH-Cavities	resonance, laser, simulation, operation	214
	M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany K. Aulenbacher HIM, Mainz, Germany W.A. Barth, V. Gettmann, S. Mickat GSI, Darmstadt, Germany
	Funding: Work supported by HIM, GSI, BMBF Contr. No 05P12RFRBL Superconducting structures are very susceptible to external influences due to their thin walls and their narrow bandwidth. Even small mechanical deformations caused by dynamic effects like microphonic noise, pressure fluctuations of the liquid helium bath or Lorentz-Force-Detuning can lead to resonance frequency changes of the cavity which are much larger than the bandwidth. To compensate the slow and fast resonance frequency variations during operation a compact frequency tuner prototype equipped with a stepper motor and a piezo actuator has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. In this paper, the tuner design and the results of first room temperature measurements of the tuner prototype are presented.
	Poster MOPP068 [2.304 MB]

MOPP070	Final Design for the BERLinPro Main Linac Cavity	HOM, linac, emittance, dipole	217
	A. Neumann, J. Knobloch HZB, Berlin, Germany K. Brackebusch, T. Flisgen, T. Galek, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany B. Riemann, T. Weis DELTA, Dortmund, Germany
	Funding: This work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities based on a modified Cornell ERL design combined with JLab's waveguide HOM damping approach. This paper will summarize the final optimization of the end-cell tuning for minimum external Q of the HOMs, coupler kick calculations of the single TTF fundamental power coupler as well as multipole expansion analysis of the given modes and a discussion on operational aspects.
	Poster MOPP070 [1.561 MB]

MOPP071	BESSY VSR 1.5 GHz Cavity Design and Considerations on Waveguide Damping	damping, HOM, SRF, operation	221
	A.V. Velez, J. Knobloch, A. Neumann HZB, Berlin, Germany
	The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.5ps) bunches in the storage ring with the present user optics. To this end, new high-voltage L-Band superconducting multi-cell cavities must be installed in one of the straights of the ring. These 1.5 GHz and 1.75 GHz cavities are based on 1.3 GHz systems being developed for the BERLinPro energy-recovery linac. This paper describes the baseline electromagnetic design of the first 5-cell cavity operating at 1.5 GHz.
	Poster MOPP071 [1.088 MB]

MOPP074	Digital Filters Used for Digital Feedback System at cERL	LLRF, controls, feedback, operation	227
	F. Qiu, D.A. Arakawa, H. Katagiri, H. Matsumoto, S. Michizono, T. Miura KEK, Ibaraki, Japan
	As a test facility for the future KEK 3-GeV energy recovery linac (ERL) project, the compact ERL (cERL) features three two-cell cavities for the injector and two nine-cell cavities for the main linac. Digital low-level radio frequency (LLRF) systems have been developed to realize highly accurate RF control. In order to reduce the influence of clock jitter and to suppress the parasitic modes in the multi-cell cavities, we have developed several types of digital filters, including a first-order IIR filter, a fourth-order conjugate poles IIR filter and a notch filter. Furthermore, to design a more effective and robust controller (such as an H-infinite controller, or repetitive controller), we need to acquire more detailed system knowledge. This knowledge can be gained by using modern system identification methods. In this paper, we present the latest applications in the LLRF systems of the cERL. identification methods. In this paper, we have compared the performance of these different type filters in cERL. The preliminary result of the system identification will be also described.

MOPP078	RF Power Systems for the FAIR Proton Linac	klystron, linac, proton, electronics	236
	J. Lesrel, C. Joly IPN, Orsay, France E. Plechov, A. Schnase, G. Schreiber, W. Vinzenz GSI, Darmstadt, Germany
	In the framework of collaboration between the FAIR project, GSI, and CNRS, the IPNO lab is in charge of providing the high power RF components for a cavity test stand and for the planned FAIR proton Linac. This Linac will be connected to the existing GSI synchrotron SIS18 for serving as an injector for the new FAIR facility. The 70 MeV FAIR proton Linac design contains a 3 MeV RFQ, and a DTL based on Cross-bar H-mode cavities (CH). It will operate with pulsed RF at 325.224 MHz with a width of 200 μs and a repetition rate of 4 Hz. The planned RF systems of the proton Linac will be presented as well as the description of the test stand. The first power test results are obtained with a Thales klystron developed jointly with CNRS. Three solid state amplifiers made by Sigmaphi Electronics for the bunchers will also be described in this paper.

MOPP081	The ECT System for RAON's Cavities	SRF, experiment, niobium, controls	242
	M.J. Joung, Y. Jung, H.J. Kim IBS, Daejeon, Republic of Korea
	The ECT system is in use for Nb surface control in many laboratories. This system can inspect Nb surface quickly using high resolution. The ECT system for RAON's cavity was made with the feature : It has 3-axis acting probe movement system, It can inspect big size of Nb sheet, which is 1m by 1m and It contain the analysis program that can show the result as 2D and 3D image as well as relative figure of surface level. The standard sample was made with various sizes of defects using the same Nb sheet that was used to make RISP cavity. The ECT system conditioining was carried out to optimize ECT operation on the frequency, the range is from 300kHz to 2MHz. The result of 900 kHz shows the strongest signal. The conditioning experiment on other parameter will be carried out in near future. .

MOPP082	Superconducting Linac for RISP	linac, cryomodule, ion, quadrupole	245
	H.J. Kim, H.J. Cha, M.O. Hyun, H.C. Jung, Y.J.K. Kim, M. Lee IBS, Daejeon, Republic of Korea
	The RISP (Rare Isotope Science Project) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. It can deliver ions from proton to Uranium. Proton and Uranium beams are accelerated upto 600 MeV and 200 MeV/u respectively. The facility consists of three superconducting linacs of which superconducting cavities are independently phased. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the RISP linac design, the prototyping of superconducting cavity and cryomodule.

MOPP090	Adjustment of the Coupling Factor of the Input Coupler of the ACS Linac by a Capacitive Iris in J-PARC	coupling, simulation, linac, ion	264
	J. Tamura, H. Ao, K. Hirano, Y. Nemoto, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan H. Asano Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan F. Naito, K. Takata KEK, Ibaraki, Japan
	Annular-ring Coupled Structure (ACS) cavities have been installed to increase the beam energy of the Japan Proton Accelerator Research Complex (J-PARC) linac from 181 to 400 MeV in the maintenance period of 2013. Some of the pillbox type input couplers with a ceramic window to the ACS cavity have a larger coupling factor than the target value by an avoidable manufacturing error. To adjust the coupling factor, a capacitive iris was introduced in the rectangular waveguide near the coupler. As a result, it has been confirmed that the iris decreases the coupling factor to a target value without any significant increase in temperature and in a discharge rate during high-power operation. In this paper, the design procedure of the capacitive iris and the result of the coupling factor adjustment are presented.

MOPP093	Evaluation of Beam Energy Fluctuations Caused by Phase Noises	linac, experiment, timing, electron	273
	H. Hanaki, H. Dewa, S. Suzuki, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan T. Asaka, T. Ohshima RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results.

MOPP099	Compact Proton Injector for Synchrotrons	rfq, linac, proton, quadrupole	291
	A.D. Kovalenko, A.V. Butenko JINR, Dubna, Moscow Region, Russia A. Kolomiets, A.S. Plastun ITEP, Moscow, Russia
	Compact linac comprising two sections of different RFQ structures was designed. The first section is conventional RFQ with output energy 3 MeV whereas the second one is RFQ with trapezoidal modulation of vanes. The linac output energy is 8 MeV. The both structures operate at frequency of 352 MHz. The total length of machine is less than 8 m. The output pulsed beam current is of 40 mA. The design is suitable for both as NICA injection complex and proton superconducting medical synchrotron.

MOPP101	Design of the 4MeV RFQ for the Helium Beam Irradiatior	rfq, controls, ion, ion-source	294
	H.-J. Kwon, Y.-S. Cho, H.S. Kim, K.T. Seol, Y.-G. Song KAERI, Daejon, Republic of Korea
	Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government. A RFQ is considered as a main accelerator of the helium beam irradiation system for the power semiconductor in Korea Multipurpose Accelerator Complex (KOMAC). The RFQ was designed to accelerate the He²⁺ beam up 4MeV with 10mA peak beam current. We chose a vane type RFQ with 200MHz operating frequency. The RFQ will be operated with the frequency tracking mode supplied by the digital low level rf control system. In this paper, the design of the 4MeV RFQ is presented and the beam irradiation system including rf system, control system, utility system, is discussed.

MOPP103	Fault Tolerance and Consequences in the MYRRHA Superconducting Linac	linac, operation, cryomodule, simulation	297
	F. Bouly LPSC, Grenoble Cedex, France J.-L. Biarrotte IPN, Orsay, France D. Uriot CEA/DSM/IRFU, France
	Funding: This work is being supported by the European Atomic Energy Community’s EURATOM) Seventh Framework Programme under grant agreement n°269565(MAX project). The MYRRHA project aims at the construction of new irradiation complex in Mol (Belgium) to demonstrate the transmutation feasibility with an Accelerator Driven System (ADS). In its subcritical configuration, the MYRRHA facility requires a proton flux with a maximum power of 2.4 MW (600 MeV - 4 mA). Such a continuous wave beam will be delivered by a superconducting linac which must fulfil very stringent reliability requirements to ensure the safe ADS operation with a high level of availability. In this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid failures mitigations. Beam dynamics studies on the fault tolerance capability of the MYRRHA superconducting linac will be presented. The results will be mainly focused on RF failure compensation scenarios: when one or several superconducting cavities are lost in the linac. The impact on the R&D to enable fast retuning procedures in the linac will also be discussed.

MOPP107	Results from the Installation of a New 201 MHz RF System at LANSCE	DTL, electronics, controls, linac	303
	J.T.M. Lyles, C.L. Arnold, W.C. Barkley, J. Davis, A.C. Naranjo, M.S. Prokop, D. Rees, G. M. Sandoval, Jr. LANL, Los Alamos, New Mexico, USA D. Baca, R.E. Bratton, R.D. Summers Compa Industries, Inc., Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. The LANSCE RM project is restoring the linac to it’s original high power capability after the power grid tube manufacturer could no longer provide triodes that could consistently meet our power requirements. High duty factor Diacrodes® now supply RF power to the largest DTL tank. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. The power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce as much as 3.5 MW peak and 420 kW of mean power. A digital low level RF control system was developed to complement these new linear amplifiers. Design and testing was completed in 2012, with commercialization following in 2013. The first installation is commissioned. The two remaining high power RF systems for tanks 3 and 4 will be replaced in subsequent years using a hybrid old/new RF system until the changeover is complete. Features and operating results of the replacement system are summarized, along with observations from the rapid-paced installation project.

MOPP108	Vertical Electro-Polishing of Nb Nine-Cell Cavity Using Cathode with Variable-Geometry Wings	cathode, experiment, power-supply, status	307
	K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan K. Ishimi MGI, Chiba, Japan
	Marui Galvanizing Co. Ltd. has been studying on Vertical Electro-Polishing (VEP) of Nb superconducting accelerator cavity for the mass-production and cost-reduction of Electro-Polishing (EP) process in collaboration with KEK. And we invented VEP process by a cathode with variable-geometry wings to get uniform distributions of both electric current and EP solution flow. Using this cathode, we performed various tests of VEP with Nb single-cell cavities. In this article, we will report fabrication of the first VEP facility for Nb nine-cell cavity and the VEP results using cathode with variable-geometry wings.

MOPP110	Multipacting Prediction for the 10⁶.1 MHz Quarter Wave Resonator	simulation, ISAC, experiment, electron	313
	M. Gusarova, I.I. Petrushina, E.A. Savin, A.N. Stolbikova MEPhI, Moscow, Russia V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	The results of analytical calculations and numerical simulations of multipacting in the 10⁶.1 MHz Quarter Wave Resonator (QWR) are presented. Resonant voltages, impact energies and corresponding particle trajectories are obtained. In this paper we compare CST PS and MultP-M 3D simulation results for multipacting in the cavity.

MOPP114	SNS Linac Upgrade Plans for the Second Target Station	linac, cryomodule, klystron, rfq	320
	J. Galambos, D.E. Anderson, M.P. Howell, S.-H. Kim, M.A. Plum, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA M.E. Middendorf ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The Second Target Station (STS) upgrade for the Spallation Neutron Source (SNS) proposes the addition of a short pulse, long wavelength neutron scattering station. In order to provide world-class intensity at the additional station, the SNS linac beam power capability is doubled, to 2.8 MW. This will be accommodated by a 30% increase in the beam energy to 1.3 GeV and a 50% increase in beam current. The beam energy increase will be provided by the addition of 7 additional cyro-modules and supporting RF equipment in space provided during the original SNS construction. The beam current increase will be provided by improved ion source and a reduced chopping fraction, and will require increases in the RF and high voltage modulator systems to accommodate the additional beam loading. Initial plans will be presented. The proposed linac upgrade path will be described.

MOPP115	Plasma Processing of Nb Surfaces for SRF Cavities	plasma, SRF, accelerating-gradient, vacuum	323
	P.V. Tyagi, M. Doleans, S.-H. Kim ORNL, Oak Ridge, Tennessee, USA R. Afanador, C.J. McMahan ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Field emission is one of the most critical issues to achieve high performances of niobium (Nb) superconducting radio frequency (SRF) cavities. Field emission is mainly related to contaminants present at top surface of SRF cavities that act as electron emitters at high gradient operation and limit the cavity accelerating gradient. An R&D program at the Spallation Neutron Source (SNS) is in place* aiming to develop an in-situ plasma processing technique to remove some of the residual contaminants from inner surfaces of Nb cavities and improve their performance. The plasma processing R&D has first concentrated on removing hydrocarbon contamination from top surface of SRF cavities. Results from the surface studies on plasma processed Nb samples will be presented in this article and showed the removal of hydrocarbons from Nb surfaces as well as improvement of the surface workfuntion (WF). *M. Doleans et al. “Plasma processing R&D for the SNS superconducting linac RF cavities” Proceedings of 2013 SRF workshop, Paris, France
	Slides MOPP115 [1.405 MB]

MOPP117	Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole	dipole, multipole, survey, emittance	326
	A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

MOPP118	C-Band Load Development for the High Power Test of the SwissFEL RF Pulse Compressor	impedance, klystron, vacuum, coupling	329
	A. Citterio, J. Stettler, R. Zennaro PSI, Villigen PSI, Switzerland
	The SwissFEL C-band Linac will have 26 RF modules, each one consisting of a solid-state modulator and a 50 MW klystron that feeds a pulse compressor and four two meters long accelerating structures. The pulse compressor is of the Barrel Open Cavity type (BOC). A first prototype was successfully produced and high-power tested, reaching for full power klystron operation a peak power of 300 MW. For testing this BOC at maximum RF power, a broadband load was designed and built, based on a ridge waveguide design and high permeability stainless steel. Based on the experience gained at CERN for CLIC X-band high power loads, the RF design of the load was optimized to ensure high losses for a quite large range of magnetic steels. Test pieces were realized in three different magnetic steels to choose the best suited material commercially available. This paper reports about the RF design, material study, production and impressive high power results of this C-band load.

MOPP123	Development Activities of Accelerator Instruments for SACLA	controls, acceleration, klystron, laser	342
	Y. Otake, T. Asaka, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Ego, S. Matsubara JASRI/SPring-8, Hyogo-ken, Japan
	The X-ray free-electron laser, SACLA, is constantly operated for user experiments aimed at new science. Experimental users demand further experimental abilities, such as many experimental chances by using multi-X-ray beam lines, much better repeatability of the experiment conditions and further intense high-energy X-rays. To equip SACLA with these abilities in the future, we have developed a 2pi /3 CG acceleration structure with an acceleration gradient of over 45 MV/m to adapt operation for generating the intense high-energy X-rays. A high-voltage power supply to charge the PFN of a modulator, a klystron and an acceleration structure were developed to adapt operation for 120 pps operation from the present 30 pps, since 120 pps is more suitable for beam distribution to the multi-beam lines. To meet the experimental repeatability realized by stable timing in a pump-probe experiment, an optical-fiber length control system to mitigate timing drift below 1 fs for 10 minutes was developed. Highly precise cavity temperature control system in an injector for below ±2mK was also realized. Performances of our developed instruments were experimentally tested to be sufficient for our demands.

MOPP126	Untrapped HOM Radiation Absorption in the LCLS-II Cryomodules	HOM, cryomodule, impedance, linac	351
	K.L.F. Bane, C. Adolphsen, C.D. Nantista, T.O. Raubenheimer SLAC, Menlo Park, California, USA A. Saini, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Department of Energy contract DE–AC02–76SF00515. The superconducting cavities in the continuous wave (CW) linacs of LCLS-II are designed to operate at 2 K, where cooling costs are very expensive. One source of heat is presented by the higher order mode (HOM) power deposited by the beam. Due to the very short bunch length-especially in L3 the final linac-the LCLS-II beam spectrum extends into the terahertz range. Ceramic absorbers, at 70 K and located between cryomodules, are meant to absorb much of this power. In this report we perform two kinds of calculations to estimate the effectiveness of the absorbers and the amount of beam power that needs to be removed at 2 K.

MOPP130	A Linac-Based Approach to Modelling an Orbit Separated Cyclotron	linac, cyclotron, simulation, emittance	364
	D.C. Plostinar, G.H. Rees STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	An orbit separated cyclotron (OSC) is a new type of accelerator intended as a proton driver for Accelerator Driven Subcritical Reactors (ADSRs). A ring has been designed based on the new concept that accelerates a proton beam from 500 MeV to 1 GeV in four turns using multi-cell superconducting cavities in each period. From a beam dynamics point of view, the ring can be considered as a “wrapped-up” linac at four times the ring circumference. In this paper we present beam dynamics modelling details when using 3D linac codes and cavity field maps. We conclude that the versatility of codes such as TraceWin, allows detailed machine modelling and improved design procedures that take into account various aspects including orbit distortion caused by transverse deflecting fields in the cavities.

MOPP132	Development of a Micro-Pulse Electron Gun Based Upon pi-Mode Dual-Cavity	electron, gun, cathode, simulation	367
	L. Liao, Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	The concept of a novel micro-pulse electron gun (MPG) based upon pi-mode dual-cavity is proposed and analyzed in this paper, and we termed it as dual-cavity micro-pulse electron gun (D-MPG) as compared to single-cavity standard MPG. From simulations, it is clear that the D-MPG is capable of yielding dozens of ampere peak currents and a few ps bunch length. Thought the mechanism for dual cavity is not fully understand, the D-MPG has demonstrate the potential to be the injectors for FEL and THz radiation facilities. Also it is a good candidate to replace the thermal cathode for industrial and medical accelerator system because of the cost-effective of the D-MPG.

MOPP133	Measurements of Cavity Misalignment by Beam Induced HOM Excited in 9-cell Superconducting Cavities	HOM, simulation, dipole, experiment	370
	A. Kuramoto Sokendai, Ibaraki, Japan N. Baboi DESY, Hamburg, Germany H. Hayano KEK, Ibaraki, Japan
	Detection of cavity misalignment in the ILC superconducting cavities inside of the cryomodules can be done by using beam induced Higher Order Modes (HOM). It is beneficial to identify possible source of emittance growth by cavity misalignment. Beam pipe modes which are localized in both ends of the cavity and TE111 1/9 pi mode which is localized in the center of the cavity are focused in this research. Deviations of these electrical centers from beam trajectory reference indicate cavity misalignment and bending. We measured beam-induced HOM in STF cavities of the STF accelerator at KEK in 2012 – 2013 and TESLA cavities of FLASH at DESY in 2013. We could identify beam pipe modes and TE111 1/9 pi mode in STF cavities and TESLA cavities at around 2.1 GHz and 1.6 GHz, both of which were very small signals. The electrical center of these beam pipe mode are studied by stretched wire method, beads perturbation method and simulations by CST MICROWAVE STUDIO 2012 and HFSS 12. In this paper, the results of these measurements and simulations are summarized.

MOPP134	Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening	proton, simulation, linac, vacuum	373
	J. Rodnizki, Y. Ben Aliz, A. Grin, Z. Horvitz, A. Perry, L. Weissman Soreq NRC, Yavne, Israel G.K. Davis JLab, Newport News, Virginia, USA J.R. Delayen ODU, Norfolk, Virginia, USA
	The SARAF Prototype Superconducting Module (PSM) houses six 176 MHz Half Wave Resonators(HWR). The PSM accelerates protons and deuterons from 1.5 MeV/u to 4 and 5.6 MeV. The HWRs are highly sensitive to the coolant liquid Helium pressure fluctuations which limit the available beam power to 2kW per cavity out of 4kW RF amplifier and coupler and so might limit the available beam current to 2mA depending on the output energy. The flat shape of the cavity along the beam line in the area of the high electric field generates the high sensitivity of the Eigen mode frequency to helium pressure. The evaluated cavity sensitivity is full consistent with the measured values. It was explored that the tuning system (the fog structure) has a significant contribution to the cavity sensitivity. By using ribs or by modifying the rigidity of the fog we may reduce the HWR sensitivity by a factor of 3. This analysis is applied to study the stresses on the cavity during cool down and warm up to avoid plastic deformation as the Niobium yield is an order of magnitude lower in room temperature.

MOPP138	Fabrication and Measurements of 500 MHz Double Spoke Cavity	electron, simulation, radiation, target	385
	H. Park, J.R. Delayen JLab, Newport News, Virginia, USA J.R. Delayen, C.S. Hopper, H. Park ODU, Norfolk, Virginia, USA
	The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.
	Poster MOPP138 [2.144 MB]

TUIOA02	R&D Efforts for ERLs	linac, emittance, operation, SRF	394
	R.G. Eichhorn Cornell University, Ithaca, New York, USA
	The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 10¹¹ in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.
	Slides TUIOA02 [8.803 MB]

TUIOC01	Large Scale Testing of SRF Cavities and Modules	cryomodule, software, laser, vacuum	426
	J. Świerbleski IFJ-PAN, Kraków, Poland
	Series production of SRF cavities, s.c. quadrupole packages and accelerator modules for the European XFEL is in full swing. Mid 2014 approx. 400 cavities will be tested, the testing of quadrupoles will be almost finished, and regular module testing will be established. Thus the talk should emphasize the quasi industrial testing of these components, of course including a good overview about the used somewhat unique AMTF infrastructure.
	Slides TUIOC01 [3.094 MB]

TUIOC03	Nb3Sn - Present Status and Potential as an Alternative SRF Material	niobium, linac, SRF, cryogenics	431
	S. Posen, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Nb₃Sn is a material that has the potential to have a transformative impact on SRF linacs. Due to its large critical temperature of approximately 18 K, Nb₃Sn cavities can have far smaller surface resistances at a given temperature than standard Nb cavities. This could significantly reduce the costs for infrastructure and power in cryoplants for large CW linacs. In addition, the predicted superheating field of Nb₃Sn is approximately double that of Nb, potentially doubling the maximum energy gradient. This would significantly decrease the size and cost of high energy linacs. In this work, we present recent progress in research and development for this promising material.
	Slides TUIOC03 [3.357 MB]
	Poster TUIOC03 [2.046 MB]

TUPP001	Cryogenic Performance of a New 72 MHz Quarter-Wave Resonator Cryomodule	cryomodule, cryogenics, solenoid, linac	437
	Z.A. Conway, G.L. Cherry, R.L. Fischer, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, C.E. Peters, M.A. Power, T. Reid, J.R. Specht ANL, Argonne, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. The Argonne National Laboratory ATLAS accelerator’s Intensity and Efficiency Upgrade project has been successfully finished [1]. This upgrade substantially increases beam currents for experimenters working with the existing stable and in-flight rare isotope beams and for the neutron rich beams from the Californium Rare Isotope Breeder upgrade. A major portion of this project involved the replacement of three existing cryomodules, containing 18 superconducting (SC) accelerator cavities and 9 superconducting solenoids, with a single cryomodule containing 7 SC 72.75 MHz accelerator cavities optimized for ion velocities of 7.7% the speed of light and 4 SC solenoids all operating at 4.5 K. This paper reports the measured thermal load to the 4 K and 80 K coolant streams and compares these results to the pre-upgrade cryogenic system.

TUPP002	Commissioning of the 72 MHz Quarter-Wave Cavity Cryomodule at ATLAS	cryomodule, SRF, ion, operation	440
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Hendricks, M. Kedzie, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, T. Reid, S.I. Sharamentov, G.P. Zinkann ANL, Argonne, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. A cryomodule of seven 72 MHz SC quarter-wave cavities optimized for ions with v/c=0.077 has been commissioned in the ATLAS heavy-ion accelerator at Argonne. ATLAS has a new capability for increased beam currents with low beam losses for nuclear physics experiments using stable or rare isotope beams or neutron rich beams from the Californium Rare Isotope Breeder. The main goal for the cryomodule, to provide an accelerating voltage of 17.5 MV (2.5 MV/cavity), with no detectable beam losses has been met within the first month of commissioning. Thus far, cavities and primary subsystems including high-power couplers and pneumatic tuners are operating as designed with full availability. For present levels there is practically no field emission (EPEAK=40 MV/m) and RF losses of ~5 Watts/cavity are only half of that planned. Cavity fields will continue to be gradually increased, with the limits due to cavity quench measured at VACC=3.75 MV. Due to a combination of rf design and cavity processing, effective voltages are now 2 ½ times those for any other operational cavities for this v/c. We report here on the recent online test results and technical features of the present design.

TUPP003	4 K Alignment of Superconducting Quarter-Wave Cavities and 9 T Solenoids in the ATLAS Intensity Upgrade Cryomodule	target, cryomodule, solenoid, alignment	443
	S.H. Kim, Z.A. Conway, W.G. Jansma, M. Kedzie, M.P. Kelly, P.N. Ostroumov ANL, Argonne, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. The superconducting cavities and, especially, the magnets in high intensity ion linacs need to be aligned to the beam with typical transverse tolerances of 0.25 mm and 0.1 degrees at temperatures of 1.8 – 4.5 K. This is necessary to limit the emittance growth and minimize the beam losses. A new cryomodule with 7 superconducting quarter-wave resonators and 4 superconducting solenoids has been installed and is now operated at the Argonne Tandem Linear Accelerator System (ATLAS). We developed the techniques necessary to assemble the superconducting components in this cryomodule at room temperature so that they are aligned to the beam axis at 4.5 K. We achieved transverse alignment tolerances of <0.2 mm RMS. In this paper, we will present the details of the alignment hardware, procedures and results.
	Slides TUPP003 [0.834 MB]

TUPP005	Completion of Efficiency and Intensity Upgrade of the ATLAS Facility	rfq, cryomodule, solenoid, ion	449
	P.N. Ostroumov, Z.A. Conway, C. Dickerson, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, Y. Luo, S.W.T. MacDonald, R.C. Murphy, B. Mustapha, R.C. Pardo, T. Reid, S.I. Sharamentov, K.W. Shepard, J.R. Specht, G.P. Zinkann ANL, Argonne, USA A. Perry Illinois Institute of Technology, Chicago, Illlinois, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. The ANL Physics Division has completed a major upgrade of the ATLAS National User Facility by successfully installing a new RFQ and cryomodule. The new normal conducting CW RFQ capable of providing 295 keV/u beams of any ion with m/q ≤7 from protons to uranium was fully integrated into ATLAS and has been in routine operation for more than a year. The RFQ doubled the efficiency of beam delivery to targets and opened the possibility to accelerate much higher intensity beams. Recently, the new cryomodule containing 7 high-performance 72.75 MHz superconducting quarter-wave resonators and 4 superconducting solenoids was successfully commissioned with beam. New design and fabrication techniques for these resonators resulted in record high voltages which were achieved during the beam commissioning. The new cryomodule provides 17.5 MV accelerating voltage which will be gradually raised by increasing the input RF power and improving LLRF system. The new cryomodule, which replaced 3 old cryomodules that used split-ring cavities, is also essential for high intensity stable beams. Results of beam commissioning and operation of ATLAS with the new RFQ and cryomodule will be presented.

TUPP006	Design of Relativistic Magnetron for High Power Microwave Generation	electron, simulation, extraction, cathode	452
	R. Chandra, S.R. Ghodke, A.S. Patel, A. Sharma, S.K. Singh BARC, Mumbai, India
	A Linear Induction Accelerator based upon magnetic storage, utilising magnetic switches has been made and it is capable of providing a 400 kV diode voltage, 4 kA beam current for 100 ns pulse duration with 100 Hz repetition rate. It operates in a very high repetition rate due to the use of magnetic switches in it. The lesser shot to shot variation make this system ideal for a Relativistic Magnetron operation, where a huge dependence of output power on applied voltage and applied current is observed. A relativistic magnetron with axial extraction is analytically designed and simulated for this system. This relativistic magnetron is expected to give a power of 100 MW per pulse when operated in its full rating. The design features of this relativistic magnetron are presented here. This magnetron was designed for an output microwave frequency of 2.52 GHz. *J. Benford, ''Space Applications of High-Power Microwaves'', IEEE Trans. Plasma Sci., vol. 36, no. 3, pp. 569–581, Jun. 2008

TUPP018	Analysis of Systematic and Random Error in SRF Material Parameter Calculations	simulation, extraction, SRF, niobium	465
	S.J. Meyers, M. Liepe, S. Posen Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Liepe Cornell University, Ithaca, New York, USA
	Funding: NSF Career award PHY-0841213 and DOE award ER41628 To understand the relationship between an RF cavity’s performance and the material on its surface, one must look at various parameters, including energy gap, mean free path, and residual resistance. Though SRIMP fits for seven parameters, three parameters are eliminated using measurement and literature values, and the uncertainty of the fit of the remaining four parameters is further reduced by synthesizing two 3-parameter fits, each from a different data set. To study random error, Monte Carlo simulations were performed of ideal data with added noise; for systematic error, contour plots of normalized residual sum of squares (RSS) of the polymorphic fit on inputted data were generated.
	Poster TUPP018 [1.183 MB]

TUPP019	Qualification of the Titanium Welds in the E-XFEL Cryomodule and the CE Certification	cryomodule, operation, linac, quadrupole	468
	S. Barbanotti, H. Hintz, K. Jensch, R. Klos, W. Maschmann, A. Matheisen, A. Schmidt DESY, Hamburg, Germany C. Boulch, C. Cloué, C. Madec, J.L. Perrin, T. Trublet CEA/IRFU, Gif-sur-Yvette, France J.-P. Charrier, O. Napoly CEA/DSM/IRFU, France
	The CE stamping of the one hundred 1.3 GHz cryomodules for the XFEL Linac is a main step in the process of the certification of the entire Linac as a pressure equipment. Stringent requirements on materials and the quality of the welds of the pressurised components need to be satisfied to obtain the stamp. This paper summarizes these requirements, describes the process developed to qualify each module and summarises the rework campaign on the cavity helium vessels made necessary to obtain the required quality for a reliable and safe accelerator.

TUPP021	A New Type of Waveguide Distribution for the Accelerator Module Test Facility of the European XFEL	klystron, cryomodule, shielding, operation	475
	V.V. Katalev, S. Choroba DESY, Hamburg, Germany E.M. Apostolov MicroPlus-Apostolov Ltd., Sofia, Bulgaria A.A. Seliverstov s.p.a. FERRITE Ltd., St.Petersburg, Russia
	In order to test 100 superconducting accelerator modules within two years three test benches have been created in the accelerator module test facility (AMTF) to achieve the rate of one cryomodule per week. Each RF station of the test facility consists of a 5 MW klystron, at 1.3 GHz, 1.37 ms pulse width and 10 Hz repetition rate, and a waveguide distribution system. Each waveguide distribution supplies RF power to eight cavities, four times a pair of cavities. The distribution allows for a maximum power of 1 MW per cavity when the distribution is switched to mode supplying power to only four cavities. A new type of 1 MW isolator and a new compact 5 MW power divider have been developed to achieve that goal. Several cryomodule have been already successfully tested with this setup. We present the waveguide distribution for this test stand and describe the performance of the different elements.

TUPP025	Progress on ESS Medium Energy Beam Transport	linac, quadrupole, rfq, DTL	484
	I. Bustinduy, D. Fernandez-Cañoto, N. Garmendia, A. Ghiglino, O. González, P.J. González, Z. Izaola, I. Madariaga, M. Magan, L. Muguira, J.L. Muñoz, I. Rueda, F. Sordo, S. Varnasseri, R. Vivanco ESS Bilbao, Bilbao, Spain M. Eshraqi, R. Miyamoto, A. Ponton ESS, Lund, Sweden
	The considered versatile ESS MEBT is being designed to achieve four main goals: First, to contain a fast chopper and its correspondent beam dump, that could serve in the commissioning as well as in the ramp up phases. A detailed study of the chopper rise time effects on the loss budget will be presented. Second, to serve as a halo scraping section by means of various adjustable blades. Third, to measure the beam phase and proﬁle between the RFQ and the DTL, along with other beam monitors. And ﬁnally, to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of eleven quadrupoles is used to match the beam characteristics transversally, combined with three 352.2 MHz CCL type buncher cavities, which are used to adjust the beam in order to fulfil the required longitudinal parameters. A thorough study on the optimal input beam parameters will be discussed. Quadrupole design update will be presented along with new RF measurements over the buncher prototype. Finally, updated results will be presented on the chopper and beam-dump system.
	Poster TUPP025 [5.596 MB]

TUPP031	Understanding the Error Tolerances Required to Automatically Phase the HIE-ISOLDE Linac	emittance, linac, software, experiment	496
	M.A. Fraser, J.C. Broere, S. Haastrup, D. Lanaia, D. Valuch, D. Voulot CERN, Geneva, Switzerland
	The broad experimental programme at ISOLDE means that the same radioactive beam species and energy are rarely studied twice and the cavities of the linac must be scaled or re-phased for each experiment. A software application was developed to automatically re-phase the cavities of the HIE-ISOLDE superconducting linac to the beam from computed settings. The application was developed to expedite both machine set-up in normal operation and in scenarios involving cavity failures. A beam dynamics error study will be presented in order to better understand the challenges facing the automatic phasing routine. The effects of a variety of different errors on the efficacy of the phasing application were studied, leading to a specification of the tolerances required for the calibration of the rf system and the accuracy of the survey system that monitors the positions of the cavities.

TUPP043	Design of the Phase Reference Distribution System at ESS	controls, LLRF, radiation, linac	529
	R. Zeng, H. Hassanzadegan, M. Jensen, J.M. Jurns, O.A. Persson, A. Sunesson ESS, Lund, Sweden K. Strniša Cosylab, Ljubljana, Slovenia
	PRDS (Phase reference distribution system) at ESS will provide phase reference signals for all LLRF systems and BPM systems with low phase noise and low phase drift. Phase stability requirement is currently 0.1° for short term (during pulse), 1° for long term (days to months). There are 155 LLRF systems and 165 BPM systems in total at current ESS accelerator design.

TUPP047	PXIE RFQ Bead Pull Measurements	rfq, beam-transport, quadrupole, experiment	535
	P. Berrutti, T.N. Khabiboulline, V. Poloubotko, G.V. Romanov, J. Steimel, V.P. Yakovlev Fermilab, Batavia, Illinois, USA D. Li, J.W. Staples LBNL, Berkeley, California, USA
	Funding: Work supported by D.O.E. Contract No. DE-AC02-07CH11359 Project X Injector Experiment radio frequency quadrupole has recently been built for Fermilab by Berkley laboratory. This RFQ will be placed after the low energy beam transport (LEBT) and before the medium energy beam transport (MEBT). The RFQ will operate at 162.5 MHz in CW regime; its function is to accelerate and focus particles coming from the LEBT at 30 keV, and to deliver a beam at 2.1 MeV to the MEBT. In order to make sure that the RFQ meets the specifications of field flatness and frequency the field in the vanes should be measured using bead pull technique. FNAL created a new single wire bead pull set up for the RFQ of PXIE. The measurements are used to find the electrical center of the structure, then the amplitude of the electromagnetic field in all the sectors of the RFQ; and the tuning will be based on these measurements. This paper describes the bead pull experimental set up, the software developed for this particular application and the measurements taken.
	Poster TUPP047 [1.089 MB]

TUPP049	Test Stand for 325 MHz Power Couplers	multipactoring, vacuum, pick-up, high-voltage	538
	S. Kazakov, B.M. Hanna, T.N. Khabiboulline, V. Poloubotko, O.V. Pronitchev, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	325 MHz superconducting Single Spoke resonators (SSR1) will be utilized in the Project X Injector Experiment (PXIE). Developed in Fermilab the main power coupler will be supply 2kW CW RF power to each cavity. Fermilab developed and designed the special test stand where the couplers will be tested up to 10 kW and design properties be confirmed. This paper describes the design of the coupler test stand and preliminary results of the tests.

TUPP052	SSR1 Tuner Mechanism: Passive and Active Device	cryomodule, alignment, SRF, operation	541
	D. Passarelli Fermilab, Batavia, Illinois, USA
	In this paper we present the methodology adopted in designing the mechanism responsible for controlling the resonant frequency of Single Spoke Resonators of first type (SSR1). Such device is capable of compensating the effects of external perturbations, such as pressure fluctuations and microphonics, on the frequency of SSR1. The compensation is achieved through active responses via an actuation system and passive responses which are inherent to the elastic behavior of the overall system. The first experiences in the design, assembly, QA and testing are reported.
	Poster TUPP052 [2.368 MB]

TUPP055	Progress on Euclid SRF Conical Half-Wave Resonator Project	niobium, vacuum, SRF, proton	547
	E.N. Zaplatin FZJ, Jülich, Germany T.L. Grimm Niowave, Inc., Lansing, Michigan, USA A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. Euclid conical Half-Wave Resonator (cHWR) project develops 162.5 MHz β=v/c=0.11 accelerator structure for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main idea of this project is to provide a self-compensation cavity design together with its helium vessel to minimize the resonant frequency dependence on external loads. A unique cavity side-tuning option is also under development. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests to demonstrate such possibility for the private company. Here we present the procedure of the cavity and helium vessel fabrication, cavity preparation and initial experimental results.

TUPP060	Development of a 217 MHz Superconducting CH Structure	simulation, linac, operation, accelerating-gradient	563
	M. Basten, M. Amberg, M. Busch, F.D. Dziuba, D. Mäder, H. Podlech IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher, W.A. Barth, S. Mickat HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: Helmholtz-Institut Mainz, Bundesministerium für Bildung und Forschung contract number 05P12RFRBL To compete in the production of Super Heavy Elements (SHE) in the future a 7.3 AMeV superconducting (sc) continuous wave (cw) LINAC is planned at GSI. The baseline design consists of 9 sc Crossbar-H-mode (CH) cavities operated at 217 MHz. Currently an advanced cw demonstrator is under design at the Institute for Applied Physics (IAP) at Frankfurt University. The purpose of the advanced demonstrator is to investigate a new concept for the superconducting CH structures. It is based on shorter CH-cavities with 8 equidistant gaps without girders and with stiffening brackets at the front and end cap to reduce the pressure sensitivity. One major goal of the advanced demonstrator is to show that the new design leads to higher acceleration gradients and smaller E_p/E_a values. In this contribution first simulation results and technical layouts will be presented.
	Poster TUPP060 [0.593 MB]

TUPP062	A Rebunching CH Cavity for Intense Proton Beams	linac, quadrupole, multipole, simulation	566
	M. Schwarz, C. Claessens, M. Heilmann, O. Hinrichs, D. Koser, O. Meusel, D. Mäder, H. Podlech, U. Ratzinger, A. Seibel IAP, Frankfurt am Main, Germany
	Funding: Project supported by the EU, FP7 MAX, Contract No. 269565 The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is currently under construction at the Goethe-University in Frankfurt am Main (Germany). A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final proton energy as well as for focusing the bunch longitudinally to compensate huge space charge forces at currents up to 200 mA at the final stage of extension. High current beam dynamic simulations have been performed. They include benchmarking of different beam dynamic codes like LORASR and TraceWin, as well as validating the results by measurements. Detailed examination of multipole field impact, due to the cavity’s geometry, together with error tolerance studies and thermal simulations are also performed. Furthermore, this CH rebuncher serves as a prototype for rt CH cavities at MYRRHA (Belgium), an Accelerator Driven System for transmutation of high level nuclear waste. After copper plating the cavity, RF conditioning will start soon.
	Poster TUPP062 [6.015 MB]

TUPP064	Zero-Current Longitudinal Beam Dynamics	lattice, resonance, damping, linac	572
	J.-M. Lagniel GANIL, Caen, France
	In linacs, the longitudinal focalization is done by nonlinear forces and the acceleration induces a damping of the phase oscillations. The longitudinal beam dynamics is therefore complex, even when the nonlinear space-charge forces are ignored. The three different ways to study and understand this zero-current longitudinal beam dynamics will be presented and compared.

TUPP065	RF Input Power Couplers for High Current SRF Applications	booster, SRF, linac, simulation	575
	V.F. Khan, W. Anders, A. Burrill, J. Knobloch, O. Kugeler, A. Neumann HZB, Berlin, Germany H. Wang JLab, Newport News, Virginia, USA
	High current SRF technology is being explored in present day accelerator science. The BERLinPro project is presently being built at the HZB to address the challenges involved in high current SRF machines. A 100 mA electron beam is designed to be accelerated to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling high input RF power for the gun as well as booster cavities where there is no energy recovery process. A high power co-axial input coupler is being developed to be used for the booster and gun cavities at the nominal beam current. The coupler is based on the KEK–cERL coupler design. The KEK coupler design has been modified to minimise the penetration of the tip in the beampipe without compromising on beam-power coupling ( Qext ~1 x 105). Herein we report on the RF design for the high power (130 kW) BERLinPro (BP) couplers along with the test stand for conditioning the couplers. We will also report on the RF conditioning of the TTF-III couplers modified for cw operation (low power ~ 10 kW) which will be utilised in a new 4-mA SRF Photoinjector and the BERLinPro main linac cryomodule.
	Slides TUPP065 [2.465 MB]

TUPP066	Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE	gun, SRF, electron, solenoid	578
	A. Arnold, M. Freitag, P. Murcek, J. Teichert, H. Vennekate, R. Xiang HZDR, Dresden, Germany G. Ciovati, P. Kneisel, L. Turlington JLab, Newport News, Virginia, USA
	As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (Epk=50 MV/m @ Q0=10¹⁰) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly behind the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.
	Poster TUPP066 [1.220 MB]

TUPP067	Chopper Operation for the Tandem Scrapers at the J-PARC Linac	linac, operation, software, timing	581
	K. Futatsukawa, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono KEK, Ibaraki, Japan E. Chishiro, K. Hirano, F. Sato, S. Shinozaki JAEA/J-PARC, Tokai-mura, Japan
	In the J-PARC linac, the energy upgrade from 181 MeV to 400 MeV by the installation of annular-ring coupled structure (ACS) cavities was successfully achieved in 2013. In the next stage, we will schedule the intensity upgrade by the increase of the beam current by improving the front-end in this summer. Then, the high heat load of the scraper, which stops the kicked-beam by the RF chopper, is predicted to damage the surface. Therefore, we prepare the tandem scrapers to suppress the heat load. The half of the kicked beam leads to a scraper and the residual is to the other. Its chopping expedient will be achieved by reversing the phase of the RF chopper on the periodic cycle at the low-level RF system. In this paper, I would like to introduce this system and present the result of the low-level test.

TUPP068	New SRF Facility at KEK for Mass-Production Study in Collaboration with Industries	cryomodule, SRF, operation, cryogenics	584
	H. Hayano KEK, Ibaraki, Japan
	The construction of the new SRF facility next to the KEK-STF facility has started from 2014 for the mass-production study of SRF accelerators in collaboration with industries. The new building for this facility has the dimension of 80 m x 30 m, and the plan is to install clean-room for cavity-string assembly, cryomodule-assembly facility, cryogenic system, vertical test facility, cryomodule test facility, input coupler process facility, cavity Electro-Polishing (EP) facility, and control-room/office-rooms in it. The purpose of this new SRF facility is to establish a close collaboration between SRF researchers and industries in order to prepare for the upcoming large-scale future SRF project, like ILC. This paper describes the infra-structure detail and the plan to utilize for future SRF accelerators.

TUPP071	Vortex-Penetration Field at a Groove with a Depth Smaller than the Penetration Depth	experiment, framework, vacuum	590
	T. Kubo KEK, Ibaraki, Japan
	Analytical models of the magnetic field enhancement at pits were presented at SRF2013 last year. In this presentation, I will show updated models. proceedings of SRF 2013, Paris, France (2013), p. 430

TUPP072	Studies on Wake Field in Annular Coupled Structure	wakefield, impedance, linac, acceleration	593
	Y. Liu, T. Maruta KEK/JAEA, Ibaraki-Ken, Japan K. Futatsukawa KEK, Ibaraki, Japan A. Miura JAEA/J-PARC, Tokai-mura, Japan
	LINAC injector of J-PARC (Japan Proton Accelerator Research Complex) was recently successfully upgraded from 181 MeV to 400 MeV, applying a type of coupled cavity linac (CCL) structure ACS (Annular Coupled Structure). It was warmly discussed since very beginning on the wake field in the ACS cavities, where there are CCL modes with the same number as that of cells within ~50 MHz, possibly resonating with high intensity proton/H⁻ beams. One of the most important effects from the wake field is the influence on the ACS phase scan. Analytical and simulation studies, as well as the countermeasures were prepared before the energy upgrade. Fortunately we found that detuning of the ACS was unnecessary, which helped to save much work in the commissioning. In addition we got chance to make experiment studies. It was also discussed why the wake field is not so serious as we expected at the very beginning.

TUPP073	Study of the ACS Cavity Without a Bridge Cavity	linac, coupling, proton, alignment	596
	F. Naito, K. Takata KEK, Ibaraki, Japan H. Ao, K. Hasegawa, K. Hirano, T. Morishita, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan
	J-PARC has installed the Annular-ring Coupled Structure (ACS) linac to increase the beam energy up to 400 MeV. One ACS module is composed of two accelerating tanks which are coupled by the bridge cavity. The bridge cavity simplifies the handling of the multi-tank system. While it is possible to feed the RF power into the each tanks directly with the power divider and the phase shifter instead of the bridge cavity. The rf properties of the ACS linac with the direct rf-power supply system has been measured by using the low power model made of aluminum. The measured results are described in the paper.
	Slides TUPP073 [5.042 MB]

TUPP078	High Gain FEL with a Micro-bunch Structured Beam by the Transverse-Longitudinal Phase Space Rotation	FEL, radiation, electron, cathode	607
	M. Kuriki, Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, K. Ohmi KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan R. Kato ISIR, Osaka, Japan
	FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. That results the longitudinal micro-bunch structure. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. A compact FEL facility based on this method is proposed.
	Poster TUPP078 [0.594 MB]

TUPP080	Commissioning of the MAX 700 MHz Test Stand	cryomodule, controls, operation, experiment	610
	J.-L. Biarrotte, F. Chatelet, M. El Yakoubi, N. Gandolfo, C. Joly, J. Lesrel, H. Saugnac IPN, Orsay, France A. Bosotti, R. Paparella, P. Pierini INFN/LASA, Segrate (MI), Italy F. Bouly LPSC, Grenoble Cedex, France I. Martin-Hoyo ADEX, Madrid, Spain
	The MYRRHA project aims at the construction of an Accelerator Driven System demonstrator. The criticality will be sustained by an external spallation neutron flux produced thanks to a 600 MeV high intensity proton beam. This beam will be delivered by a superconducting linac which must fulfil very stringent reliability requirements. Under the MAX (MYRRHA Accelerator eXperiment) program, which aims at pursuing the R&D activities on the ADS-type accelerator, a 700 MHz Cryomodule was developed. The main goal of this test stand is to dispose of a facility to carry out “real scale” reliability oriented studies on a RF Superconducting cavity of the high-energy linac section. This module holds 5-cells elliptical cavity equipped with its blade cold tuning system and its coaxial power coupler. The experimental work undertaken at IPN Orsay, has allowed to fully qualify the module in machine configuration (high RF power, at 2K), including assessment of the tuning system and measurement of microphonics spectrums. During this study the dynamic behavior of the fast tuning system of the cavity was also measured. We review here the obtained results and lessons learnt by operating this module.

TUPP082	The MYRRHA Spoke Cryomodule Design	cryomodule, linac, framework, cryogenics	613
	H. Saugnac, J.-L. Biarrotte, S. Blivet, P. Duchesne, N. Gandolfo, J. Lesrel, G. Olry, E. Rampnoux, D. Reynet IPN, Orsay, France
	In the framework of the MAX project, dedicated to the detailed study of the MYRRHA facility LINAC, the engineering study of the ‘Spoke’ cavities cryomodule, situated in the low energy superconducting section, has been achieved. The beam optics, highly constrained by strong reliability requirements, leads to a modular cryomodule composed of two β=0.37, 352 MHz, single bar ‘Spoke’ cavity cooled at 2K. The power coupler design, not studied in detail under the MAX project, is directly taken from a 20 kW continuous wave 352 MHz coupler designed and successfully tested in the framework of the previous EUROTRANS and EURISOL projects. The cold tuning system is identical to the one designed for the ESS ‘Spoke’ cavities. We present in this paper, the RF, the mechanical and the thermal design of the complete cryomodule as well as the optimization and simulations of its individual components (Cavity, Cryostat, Tuning System…).

TUPP083	Design and Analysis of Slow Tuner in the Superconducting Cavity of RISP	superconducting-cavity, niobium, target, SRF	616
	M.O. Hyun, H.C. Jung, H.J. Kim IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the Rare Isotope Science Project of Institute of Basic Science funded by the Ministry of Science, ICT and Future Planning and National Research Foundation. Superconducting cavity is one of the most complex systems from the view of mechanical engineering, which is installed and operated in the superconducting linear accelerator. In order to operate SC cavity properly and precisely, superconducting cavity needs many sub-systems, including power coupler for applying RF power inside cavity, and liquid helium jacket for cooling cavity until reaching to the superconducting conditions. And, also cavity needs frequency tuning system for adjusting operating frequency when RF frequency of cavity is changed with outer disturbances such as liquid helium fluctuation, mechanical deformation due to vacuum condition of cavity. Generally, this tuning system is called as a tuner. There are two types of tuner, one is slow tuner which operates with motor, and the other is fast tuner which operates with piezo-electric actuator. This paper describes about design process and analysis results about slow tuner.

TUPP084	Surface Treatment Facilities for SCRF Cavities at RISP	vacuum, superconducting-cavity, niobium, superconducting-RF	619
	J. Joo, D. Jeon, M.J. Joung, Y. Jung, H.J. Kim, M. Lee IBS, Daejeon, Republic of Korea
	Rare Isotope Science Project is engaged in the fabrication of four types of superconducting RF cavities. The surface treatment is one of the important processes of superconducting RF cavity fabrication. New superconducting RF cavity processing systems have been designed and developed for the etching of niobium in buffered chemical polish at RISP. The safety precautions used in protecting the operator from the acids used in the etchant and from the fumes given of during the process are discussed. All of the new hardware will be located in RISP Munji Superconducting Cavity Test Facility.

TUPP085	RAON Cryomodule Design for QWR, HWR, SSR1 and SSR2	cryomodule, simulation, linac, vacuum	622
	W.K. Kim, H. Kim, H.J. Kim, Y. Kim, M. Lee, G.-T. Park IBS, Daejeon, Republic of Korea
	The accelerator called RAON which will be built in Korea has four kinds of superconducting cavities such as QWR, HWR, SSR1 and SSR2, operating at 2 K and 4.5 K [1]. The current status of design for the QWR, HWR, SSR1 and SSR2 cryomodules are reported. The issues included in the paper are thermal and structural design results of the components such as supports and thermal shield in the cryomodules. The cryomodule hosts the superconducting cavities in high vacuum and thermally insulated environment in order to maintain the operating temperature of superconducting cavities. It also keeps the cavities in a good alignment to the beam line. It has an interface for supplying RF power to cavities between cold and warm components. The whole configuration of the integrated system is also presented. This paper presents the detailed design of the cryomodule.

TUPP086	RAON Superconducting Radio Frequency Test Facility Construction	radiation, cryogenics, SRF, electron	625
	H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin IBS, Daejeon, Republic of Korea
	Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP088	The Fabrication of the β=0.12 HWR at RISP	niobium, target, vacuum, electron	628
	G.-T. Park, H.J. Cha, Y. Jung, H. Kim, W.K. Kim IBS, Daejeon, Republic of Korea
	At RISP, the superconducting cavities have been developed to construct RAON, the heavy ion accelerator. Among the cavities, the fabrication of the QWR (Quarter wave resonator) and the HWR (Half wave resonator)are complete. The detailed fabrication processes including material inspection, forming, the electron beam welding, and the clamp up test are described.

TUPP089	Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac	DTL, linac, simulation, resonance	631
	M.R. Khalvati IPM, Tehran, Iran S. Ramberger CERN, Geneva, Switzerland
	The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H–beams of up to 40 mA average pulse current from 3 to 50 MeV. The structure consists of three cavities. The first cavity (Tank1) is a 3.9 m long tank containing 38 drift tubes, 10 fixed tuners, 2 movable tuners and 12 post-couplers, operating at a frequency of 352.2 MHz and an average accelerating field of 3.1 MV/m. This paper reports on the results and procedures used for the low–power tuning, stabilization and power coupler tuning carried out on the first Linac4 DTL tank. The upgrade of the bead pull measurement system and twists to the well-known tilt sensitivity technique are discussed.

TUPP093	The Couplers for the IFMIF-EVEDA RFQ High Power Test Stand at LNL: Design, Construction and Operation	coupling, vacuum, rfq, simulation	643
	E. Fagotti, L. Antoniazzi, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, C. R. Roncolato INFN/LNL, Legnaro (PD), Italy
	In order to assess the critical aspects of the IFMIF-EVEDA RFQ construction procedure and operation, it was decided to perform a High Power Test of a subset of the RFQ consisting in its last 550 mm three modules (out of 18) plus a Prototype Module, 390 mm long, used as RF plug. These modules are going to be tested at full power in CW of INFN LNL Labs, in the so-called RFQ High Power Test Stand. For such a purpose, a RF tube-based amplifier capable of 220 kW CW output power at the operational frequency of 175 MHz was purchased from an Italian company. A critical component of this test is the RF power coupler. Therefore INFN-LNL developed a design of two identical water-cooled loop antenna couplers, built with OFE copper and vacuum sealed with a commercially available 6”1/8 Alumina planar window. These couplers were tested separately on an aluminium coupling cavity. In particular one of them acts as a power feeder, while the other one, connected with a 200 kW water-cooled load, acts as a receiver. In this paper, the main aspects of the design, construction and tests performed on the couplers and coupling cavity will be described.

TUPP094	Recent Progress of Beam Commissioning at J-PARC Linac	linac, operation, acceleration, DTL	646
	T. Maruta J-PARC, KEK & JAEA, Ibaraki-ken, Japan K. Futatsukawa, T. Miyao KEK, Ibaraki, Japan M. Ikegami FRIB, East Lansing, Michigan, USA Y. Liu KEK/JAEA, Ibaraki-Ken, Japan A. Miura, H. Sako JAEA/J-PARC, Tokai-mura, Japan
	We installed Annular-type Coupled Structure (ACS) linac in year 2013 in present linac downstream to extend the beam energy from 181 to 400 MeV. The beam commissioning had been conducted for one month in last December to January, and then we successfully extract 400 MeV beam. Whereas, we stably operate the linac at peak current of 15 mA, which is equivalent to 300 kW at the extraction of 3 GeV RCS, we observe unexpected residual radiations in ACS section. In this presentation, we review the recent progress in beam commissioning and beam loss study.

TUPP095	High-Power Test Results of the RFQ III in J-PARC Linac	rfq, operation, vacuum, ion	649
	T. Morishita, K. Hasegawa, K. Hirano, Y. Kondo, H. Oguri, S. Yamazaki JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Hori JAEA, Ibaraki-ken, Japan F. Naito, T. Sugimura, A. Takagi KEK, Ibaraki, Japan
	The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The beam energy of the linac has been upgraded from 181MeV to 400MeV in 2013. For the beam current upgrade, the new frontend (RF ion source, RFQ, chopping system) installation is scheduled in summer 2014 for 1MW operation at RCS. The RFQ III, which is designed for 50mA beam acceleration from 0.05MeV to 3MeV, has been fabricated and the high-power test has started at April 2013 at the test station in the J-PARC. The test station consists of the ion source, the LEBT, the RFQ, and the diagnostics devices. The nominal RF power and RF duty of the RFQ III are 380kW and 3%(0.6ms and 50Hz), respectively. The high-power conditioning reached to the 120% of the nominal power with 1.5% (0.6ms, 25Hz) RF duty within 24 hours. Then, we performed the beam operation at the test station and measured beam parameters after the RFQ III. The results of the high-power conditioning and the stability of the RFQ operation with beam will be discussed.

TUPP101	Vertical Electro-Polishing of Nb Single-Cell Cavity Using Cathode with Variable-Geometry Wings and Its Results of Vertical Test	cathode, power-supply, target, experiment	662
	K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi MGH, Hyogo-ken, Japan P. Carbonnier, F. Éozénou, C. Servouin CEA/DSM/IRFU, France H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan K. Ishimi MGI, Chiba, Japan C. Madec, L. Maurice CEA/IRFU, Gif-sur-Yvette, France
	Marui Galvanizing Co. Ltd. has been studying Vertical Electro-Polishing (VEP) on Nb superconducting accelerator cavity with the goal of mass-production and cost-reduction of Electro-Polishing (EP) process in collaboration with KEK and CEA Saclay. And we invented variable-geometry wings cathode for VEP process to get uniform distributions of both electric current and EP solution flow. Using this cathode, we performed various tests of VEP with Nb single-cell cavities. In this article, we will report the results of vertical test of Nb single-cell cavity which is VEP’ed by cathode with variable-geometry wings.

TUPP103	The Beam Envelope Control in SC Linac for the Proton Radiotherapy	linac, controls, proton, simulation	665
	A.V. Samoshin, I.A. Ashanin, S.M. Polozov MEPhI, Moscow, Russia
	Proton cancer therapy is conventionally based on normal conducting synchrotrons and cyclotrons. The high electrical power consumption and especial devices necessary to energy variation are main problems of such facilities. Superconducting linacs based on short identical independently phased cavities have a seriously progress and it's development allow to propose their using for medical application. High accelerating gradient and small capacity losses nearly 10^-4 Vt/m are main advantages in advance of normal conducting facilities, the energy variation can be realized by means of RF field amplitude and phase variation in a number of cavities. Besides linac structures are lack of unwieldy magnetic system, simplicity of input and output of particles and high current densities. The parameters choose and the optimization for SC linac structure with energy up to 240 MeV and envelope control will discuss in this paper. The simulation was done using BEAMDULAC-SCL code. The study of beam dynamics will direct to realize the energy variation in range 150-240 MeV with beam quality preservation. A.V. Samoshin. Proc. of LINAC2012, Tel-Aviv, Israel, TUPB069, p. 630 - 632

TUPP106	RF Characteristics of 20K Cryogenic 2.6-cell Photocathode RF-gun Test Cavity	gun, simulation, cryogenics, database	671
	T. Sakai, M. Inagaki, K. Nakao, K. Nogami, T. Tanaka LEBRA, Funabashi, Japan M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida KEK, Ibaraki, Japan T.S. Shintomi Nihon University, Tokyo, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. The cryogenic C-band photocathode RF gun operating at 20K is under development at LEBRA in Nihon University. The RF gun is of the BNL-type 2.6-cell pillbox cavity with the resonant frequency of 5712 MHz. The 6N8 high purity OFC copper is used as the cavity material. From the theoretical evaluation of the anomalous skin effect, the quality factor Q of the cavity has been expected to be about 60000. Considering a low cooling capacity of the cryocooler system, initial operation of the RF gun is assumed at a duty factor of 0.01 %. The cavity basic design and the beam bunching simulation were carried out using SUPERFISH and General Particle Tracer (GPT). Machining of the cavity was carried out in KEK. The RF characteristics measured at room temperature and 20K will be reported.

TUPP108	HOM and Impedance Study of RF Separators for LCLS II	HOM, dipole, superconducting-RF, impedance	674
	S.U. De Silva, J.R. Delayen, B.R.P. Gamage, G.A. Krafft, T. Satogata ODU, Norfolk, Virginia, USA R.G. Olave Old Dominion University, Norfolk, Virginia, USA
	The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.
	Poster TUPP108 [1.032 MB]

TUPP109	Cryogenic Testing of High-Velocity Spoke Cavities	cryogenics, acceleration, proton, linac	677
	C.S. Hopper, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park JLab, Newport News, Virginia, USA
	Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

TUPP112	Study of a C-Band TW Electron Gun for SwissFEL	gun, cathode, emittance, klystron	686
	M. Schaer, A. Citterio, P. Craievich, L. Stingelin, R. Zennaro PSI, Villigen PSI, Switzerland
	For a future upgrade of the SwissFEL facility, the replacement of the S-band standing wave electron gun by a C-band standing wave, or traveling wave gun is investigated. The full model of the C-band TW gun is calculated with HFSS and is characterized by an almost vanishing group velocity in the first cell to increase the field at the cathode. ASTRA simulations predict that in the case of the C-band SW gun, a two times higher peak current of ~ 40 A can be generated while still preserving the low slice emittance of ~ 0.2 um at 200 pC, due to the higher electric field on cathode and improved magnetic focusing. This would help to halve the overall beam compression factor, relax the phase stability requirement of S- and X-band systems operated off-crest for compression and decrease the gain curve in theμbunch instability. Compared to the SW gun, a TW gun provides a more homogeneous acceleration and does not require any circulator. In this study, the preliminary RF design and beam performance of a C-band TW gun is presented and compared to a pure C-band SW gun presently under design at Paul Scherrer Institut and to the operating S-band SW gun.

TUPP113	High RF Power Test of Coupled RFQ-SFRFQ Cavity	rfq, simulation, impedance, detector	689
	W.L. Xia, J.E. Chen, S.L. Gao, F.J. Jia, Y.R. Lu, Z. Wang, J. Zhao, K. Zhu PKU, Beijing, People's Republic of China
	Funding: This work was supported in part by the National Natural Science Foundation of China under Grant No. 11075008, 11079001 and 11175009. A new combined accelerator that couples radio frequency quadrupole (RFQ) and separated function radio frequency quadrupole (SFRFQ) in a single cavity has been designed and manufactured. Recently, the performance of the cavity under high RF power was tested with an upgraded RF power source. The inter-vane voltages of both RFQ section and SFRFQ section were measured by using high purity germanium detector and the corresponding measurement system. The measured shunt impedance is about 546.9 kΩ•m, which means the cavity needs 19.5 kW for the designed inter-vane voltage of 65 kV. The results are well consistent with the cavity design.
	Poster TUPP113 [0.764 MB]

TUPP117	Commissioning of Vertical Test Stand Facility for 2 K Testing of Superconducting Cavities at RRCAT	radiation, shielding, controls, cryogenics	695
	S.C. Joshi, A. Chauhan, P. Fatnani, P.D. Gupta, M.K. Kumar, P.K. Kush, P. Mohania, S. Raghvendra, P. Shrivastava, S.K. Suhane RRCAT, Indore (M.P.), India
	Raja Ramanna Centre for Advanced Technology (RRCAT) has developed a 2K vertical Test Stand (VTS) facility for characterization of Superconducting RF (SCRF) cavities, under Indian Institution Fermilab Collaboration (IIFC). The VTS facility comprises of a large size liquid helium (LHe) cryostat, cryogenic system, RF power supply, control and data acquisition system and radiation monitoring system. It will facilitate testing of superconducting cavities of different frequencies ranging from 325 MHz low beta to 650 MHz / 1.3 GHz medium and high beta cavities. The helium vessel has a capacity to store up to 2900 litres of liquid Helium. The cryostat is installed inside a vertical pit. It is equipped with facilities for supply of liquid nitrogen and liquid helium and vacuum system for pumping out helium gas to lower the temperature of liquid helium bath down to 1.8 K. A 200 W, 1.3 GHz RF system has been indigenously developed for testing of the SCRF cavities. The VTS facility has now been commissioned and its performance validation has been successfully carried out by benchmarking it with respect to the facility at the Fermilab.

TUPP119	Design Studies for Medium and High beta SCRF Cavities for Indian Spallation Neutron Source	linac, HOM, lattice, quadrupole	699
	A.R. Jana, V. Kumar RRCAT, Indore, India
	There is a plan to build a 1 GeV H⁻ linac for the proposed Indian Spallation Neutron Source (ISNS) at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore. The medium and high energy section of the ISNS linac will consist of beta_g=0.61, as well as beta_g = 0.9, 650 MHz, 5-cell superconducting radiofrequency (SCRF) cavities, for which detailed electromagnetic design studies have been performed. During our design study, we have evolved a generalized procedure for the optimization of geometrical parameters of multi-cell SCRF cavities. Studies on higher order modes supported by the cavity and its effect on beam dynamics, as well as on heat load to the cavity have been performed, which constitute an important aspect of the design study. Finally, detailed studies on Lorentz Force Detuning (LFD) have been performed, and design of the cavity has been optimized to minimize the effect due to the LFD. The paper discussed the details of the calculations and the studies that have been performed during the design study.

TUPP123	Design of Novel RF Sources to Reduce the Beam Pace-Charge Effects	electron, klystron, space-charge, cathode	712
	M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: DOE Traditional RF sources, such as Klystrons, TWT require a magnet (such as a solenoid) in order to maintain the electron beam focusing, compensating the particle repulsion caused by space charge effects. We designed a novel RF source with an alternative approach that reduces beam space charge problems. This paper shows the design of the device, with a new formulation of the Child’s Law, and the mode-beam stability analysis. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics.
	Poster TUPP123 [0.172 MB]

TUPP133	Optimization of the RF Cavity of the Medical Purpose Electron Linac by Using Genetic Algorithm	electron, impedance, linac, acceleration	726
	S. Shin, J.-S. Chai SKKU, Suwon, Republic of Korea
	A compact electron linear accelerator for the medical application has been developing at Sungkyunkwan University. Due to this electron linac is attached on the robot arm or gantry, it should be compact enough to be held by the structure. An X-band technology has been used to meet the requirements for the compact linac. Because the particle accelerator is complex and sensitive machine to design it takes a lot of time to get a good performance accelerator. In this research, a special technique named single-objective genetic algorithm for the optimization process has been applied to achieve a better RF cavity design by changing various geometric parameters.

TUPP138	Analysis of New High-Q0 SRF Cavity Tests by Nitrogen Gas Doping at Jefferson Lab	injection, SRF, niobium, vacuum	736
	A.D. Palczewski, R.L. Geng, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In order to refine systematic understanding and establish confident process control, Jefferson Lab has joined with partners to investigate and thoroughly characterize the dramatically higher Q0 of 1.3 GHz niobium cavities first reported by FNAL in 2013[1]. With partial support from the LCLS-II project, JLab has undertaken a parametric study of nitrogen doping in vacuum furnace at 800 C followed by variable depth surface removal in the 5 - 20 μm range. Q0 above 3×10¹⁰ are typical at 2.0 K and 16 MV/m accelerating field. We report observations from the single cell study and current interpretations. In addition to the parametric single cell study, we also report on the ongoing serial testing of six nitrogen-doped 9-cell cavities as baseline prototypes for LCLS-II. [1] A. Grassellino, et al., Supercon. Sci.and Tech., 2013. 26(10): p. 102001
	Poster TUPP138 [4.214 MB]

TUPP139	Design Studies with DEMIRCI for SPP RFQ	rfq, software, interface, ion	740
	B. Yasatekin, G. Turemen Ankara University, Faculty of Sciences, Ankara, Turkey A. Alacakir TAEK, Ankara, Turkey G. Unel UCI, Irvine, California, USA
	To design a Radio Frequency Quadrupole (RFQ) is a onerous job which requires a good understanding of all the main parameters and the relevant calculations. Up to the present there are only a few software packages performing this task in a reliable way. These legacy software, though proven in time, could benefit from the modern software development tools like Object Oriented (OO) programming. In this note, a new RFQ design software, DEMIRCI is introduced. It is written entirely from scratch using C++ and based on CERN's OO ROOT library. It has a user friendly graphical user interface and also a command line interface for batch calculations. It can also interact by file exchange with similar software in the field. After presenting the generic properties of DEMIRCI, its compatibility with similar software packages is discussed based on the results from the reference design parameters of SPP (SNRTC Project Prometheus), a demonstration accelerator at Ankara, Turkey.
	Poster TUPP139 [11.590 MB]

WEIOA01	Construction and RF Conditioning of the Cell-Coupled Drift Tube Linac (CCDTL) for Linac4 at CERN	linac, vacuum, coupling, quadrupole	746
	A.G. Tribendis, Y.A. Biryuchevsky, E. Kendjebulatov, Ya.G. Kruchkov, E. Rotov, A.A. Zhukov BINP SB RAS, Novosibirsk, Russia Y. Cuvet, A. Dallocchio, J.-F. Fuchs, F. Gerigk, J.-M. Giguet, J. Hansen, T. Muranaka, E. Page, B. Riffaud, N. Thaus, M. Tortrat, M. Vretenar, R. Wegner CERN, Geneva, Switzerland M.Y. Naumenko RFNC-VNIITF, Snezhinsk, Chelyabinsk region, Russia
	This paper reports on the construction experience of the Linac4 CCDTL, which took place in two Russian institutes in the framework of three ISTC projects in close collaboration with CERN. The tanks were constructed at VNIITF, Snezhinsk, while the drift tubes and supports were made at BINP, Novosibirsk. All structures were then assembled and tuned at BINP before shipment to CERN where the high-power conditioning took place. The tuning principles, quality checks and conditioning results are presented.
	Slides WEIOA01 [4.909 MB]

WEIOA04	Phase Locked Magnetrons for Accelerators	injection, cathode, controls, electron	751
	A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Magnetrons offer lower capital costs and higher efficiencies than klystrons, however are natural oscillators rather than amplifiers. This paper reviews techniques and issues for applying high efficiency L band magnetrons to long pulse, high intensity proton linacs. Reference is made to a proof of principle experiment whereby the phase of an SRF cavity was accurately controlled when energised by a magnetron.
	Slides WEIOA04 [1.224 MB]

WEIOA06	Low Level RF for SRF Accelerators	LLRF, controls, SRF, operation	760
	J. Branlard DESY, Hamburg, Germany
	Low level radio frequency (LLRF) systems are a fundamental component of superconducting RF accelerators. Since the release of the MicroTCA standard (MTCA.4), major developments in MTCA.4-based LLRF systems have taken place. State-of-the-art LLRF designs deliver better than 10^-4 relative amplitude and 10 mdeg phase stability for the vector sum control of SRF cavities. These developments in LLRF systems architecture and technology, driven by research institutes and supported by the industry are of highest importance for the European XFEL, but also for other SRF-based projects such as LCLS-II and the ESS, as well as for the next generation accelerators with 10-5 and mdeg regulation requirements.
	Slides WEIOA06 [5.812 MB]

WEIOB03	Status of RAON Heavy Ion Accelerator Project	ion, rfq, linac, target	775
	D. Jeon, H.J. Kim IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning (MSIP) and the NRF of Korea under Contract 2013M7A1A1075764. Construction of the RAON heavy ion accelerator facility is under way in Korea to build the In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) facilities to support cutting-edge researches in various science fields. At present prototyping of major components are proceeding including 28 GHz ECR ion source, RFQ, superconducting cavities, magnets and cryomodules. Superconducting magnets of 28 GHz ECR ion source are fabricated and tested. First article of prototype superconducting cavities are delivered that were fabricated through domestic vendors. Prototype HTS quadrupole is under development. Progress report of the RAON accelerator systems is presented.
	Slides WEIOB03 [6.228 MB]

Paper

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MOIOB01

Early Commissioning Experience and Future Plans for the 12 GeV Continuous Electron Beam Accelerator Facility

cryomodule, linac, operation, SRF

11

M. Spata
JLab, Newport News, Virginia, USA

Jefferson Lab has recently completed the accelerator portion of the 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility. All 52 SRF cryomodules have been commissioned and operated with beam. The initial beam transport goals of demonstrating 2.2 GeV per pass, greater than 6 GeV in 3 passes to an existing experimental facility and greater than 10 GeV in 5-1/2 passes have all been accomplished. These results along with future plans to commission the remaining beamlines and to increase the performance of the accelerator to achieve reliable, robust and efficient operations at 12 GeV are presented.

Slides MOIOB01 [2.754 MB]

MOIOC01

Status of Superconducting Electron Linac Driver for Rare Ion Beam Production at TRIUMF

cryomodule, linac, electron, TRIUMF

31

R.E. Laxdal, F. Ames, R.A. Baartman, I.V. Bylinskii, Y.-C. Chao, D. Dale, K. Fong, E.R. Guetre, P. Kolb, S.R. Koscielniak, A. Koveshnikov, M.P. Laverty, Y. Ma, M. Marchetto, L. Merminga, A.K. Mitra, N. Muller, R.R. Nagimov, T. Planche, W.R. Rawnsley, V.A. Verzilov, Z.Y. Yao, Q. Zheng, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

A MW class cw superconducting electron linac is being installed at TRIUMF as a driver for radioactive beam production through photo-fission. The ARIEL e-linac will house five 1.3GHz nine-cell cavities in three cryomodules and accelerate up to 10mA of electrons to 50MeV. A first phase of installation will see three cavities in two cryomodules installed by the end of 2014. Presently the injector cryomodule is installed and undergoing cryogenic and rf characterizations and beam acceleration tests with beam from the 300kV DC gun. The second cryomodule is being prepared for first tests. The linac status including descriptions and operating performance of installed cryogenic and rf systems, electron gun performance, cryomodule performance and the results of first beam acceleration tests will be reported.

Slides MOIOC01 [6.383 MB]

MOIOC03

Model and Beam Based Setup Procedures for a High Power Hadron Superconducting Linac

linac, simulation, laser, quadrupole

41

A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

This presentation will review methods for experimental determination of optimal operational set points in a multi-cavity superconducting high power hadron linac. A typical tuning process, including establishing correct acceleration profile and RMS bunch size matching, is based on comparison between measured data and the results of simulations from envelope, single and multi-particle models. Presence of significant space charge effects requires simulation and measurement of bunch dynamics in 3 dimensions to ensure low loss beam transport. This is especially difficult in a superconducting linac where use of interceptive diagnostics is usually restricted because of the risk of SRF cavity surface contamination. The procedures discussed here are based on non-interceptive diagnostics such as beam position monitors and laser wires, and conventional diagnostics devices such as wire scanners and bunch shape monitors installed outside the superconducting linac. The longitudinal Twiss analysis based on the BPM signals will be described. The superconducting SNS linac tuning experience will be used to demonstrate problems and their solution for real world linac tune-up procedures.

Slides MOIOC03 [1.954 MB]

MOPP001

First Experimental Results for the Superconducting Half-Wave Resonators for PXIE

niobium, proton, cryomodule, accelerating-gradient

46

Z.A. Conway, A. Barcikowski, G.L. Cherry, R.L. Fischer, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, T. Reid, K.W. Shepard
ANL, Argonne, Illinois, USA

Funding: This work was supported by the U.S. Department of energy, Offices of High-Energy Physics and Nuclear Physics, under Contract No. DE-AC02-76-CH03000 and DE-AC02-06CH11357.
The first pair of superconducting niobium half-wave resonators operating at 162.5 MHz for the FNAL PIP-II project are complete and this poster reports the cold test results. These cavities are optimized to accelerate protons/H⁻ from 2 to 10 MeV and build upon optimized electromagnetic designs and processing techniques developed at Argonne for the Intensity Upgrade of the ATLAS superconducting heavy ion accelerator.

MOPP002

Design of a Superconducting Quarter-Wave Resonator for eRHIC

electron, linac, SRF, niobium

49

S.V. Kutsaev, Z.A. Conway, M.P. Kelly, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
S.A. Belomestnykh, I. Ben-Zvi, Q. Wu, W. Xu
BNL, Upton, Long Island, New York, USA
B. P. Xiao
SBU, Stony Brook, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357
The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.

MOPP003

A Compact Linac Design for an Accelerator Driven System

linac, cryomodule, lattice, focusing

52

B. Mustapha, S.V. Kutsaev, J.A. Nolen, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A compact linac design has been developed for an Accelerator Driven System (ADS). The linac is under 150 meters in length and comprises a radio-frequency quadrupole (RFQ) and 20 superconducting modules. Three types of half-wave cavities and two types of elliptical cavities have been designed and optimized for high performance at frequencies of 162.5, 325 and 650 MHz. The lattice is being designed and optimized for operation with a peak power of 25 MW for a 25 mA – 1 GeV proton beam. The cavities RF design as well as the linac lattice will be presented along with end-to-end beam dynamics simulations for beam currents ranging from 0 to 25 mA.

MOPP012

Beam Commissioning of the SRF 704 MHz Photoemission Gun

cathode, gun, SRF, electron

70

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, G.T. McIntyre, D. Phillips, V. Ptitsyn, K.S. Smith, R. Than, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, V. Ptitsyn
Stony Brook University, Stony Brook, USA
D. Holmes
AES, Medford, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under comissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert it reached 1.9 MV with 18% duty factor, which is limited by mulitpacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. This paper presents recent commissioning results, including cavity commissioning without the cathode stalk insert, first beam commissioning of the SRF gun in pulsed regime, and the design of a multipacting-free cathode stalk.

MOPP013

Vertical Test Results of 704 MHz BNL3 SRF Cavities

HOM, SRF, electron, damping

73

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, R. Porgueddu, R. Than, D. Weiss
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
M.D. Cole, D. Holmes, T. Schultheiss
AES, Medford, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE, and Award No. DE-SC0002496 to Stony Brook University with the U.S. DOE.
An electron-ion collider (eRHIC) proposed at BNL requires superconducting RF cavities able to support high average beam current. A 5-cell niobium SRF cavity, called BNL3, was designed for a conventional lattice eRHIC design. To avoid inducing emittance degradation and beam-break-up (BBU), the BNL3 cavity was optimized to damp all dangerous higher-order-modes (HOMs) by employing a large beam pipes and coaxial antenna-type couplers. Additionally, the cavity was designed for an acceptable cryogenic load and peak surface RF fields. Two BNL3 cavities have been fabricated and tested at a vertical test facility at BNL. This paper addresses development of the SRF cavities for eRHIC, including SRF cavity design, fabrication and test results.

MOPP016

Extracting Superconducting Parameters from Surface Resistivity by Using Inside Temperature of SRF Cavities

accelerating-gradient, SRF, electron, superconductivity

80

G.M. Ge, G.H. Hoffstaetter, M. Liepe, H. Padamsee, V.D. Shemelin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The surface resistance of an RF superconductor depends on the surface temperature, the residual resistance and various superconductor parameters. These parameters can be determined by measuring the quality factor of a SRF cavity in helium-baths of different temperatures. The surface resistance can be computed from Q0 for any cavity geometry, however it is less simple to determine the temperature of the surface when only the temperature of the helium bath is known. Traditionally, it was approximated that the surface temperature on the inner surface of the cavity is the same as the temperature of the bath. This is a good approximation at small RF-field losses on the surface, but to determine the field dependence of Rs, one cannot be restricted to small field losses. Here we show how computer simulations can be used to determine the inside temperature so that Rs(Tin) can then be used to extract superconductor parameters. The computer code combines the well-known programs HEAT and SRIMP. We find that the error of the incorrect fitting method is about 10% at high RF-fields.

MOPP017

Cool Down and Flux Trapping Studies on SRF Cavities

SRF, cryomodule, linac, operation

84

D. Gonnella, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Recent results from Cornell and FNAL have shown that cool down rate can have a strong impact on the residual resistance of a superconducting RF cavity during operation. We have studied the effect of cool down rate, gradient, and external magnetic field during cool down on the residual resistance of an EP, EP+120C baked, and nitrogen-doped cavities. For each cavity, faster cool down and large gradient resulted in lower residual resistance in vertical test. The nitrogen-doped cavities showed the largest improvement with fast cool down, while the EP+120C cavity showed the smallest. The cavities were also placed in a uniform external magnetic field and residual resistance was measured as a function of applied field and cool down rate. We show that the nitrogen-doped cavity was the most susceptible to losses from trapped flux and the EP+120C cavity was least susceptible. These measurements provide new insights into understanding the physics behind the observed impact of cool down rates and gradients on the performance of cavities with differing preparations.

MOPP018

Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule

cryomodule, SRF, radiation, linac

88

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Grassellino, A. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy
Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP019

Nb3Sn Materials Studies

niobium, SRF, electron, ion

92

S. Posen, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Th. Proslier
ANL, Argonne, Illinois, USA

Nb₃Sn is a very promising material for use in SRF cavity applications, potentially offering significant improvements in quality factor and energy gradient compared to niobium. In order to better understand how to optimize this material for SRF applications, Nb₃Sn samples were prepared at Cornell via vapor deposition, using varying parameters in the coating process. Microscopic studies were performed with SEM/EDX, and studies were performed on bulk samples to measure secondary electron yield, energy gap, and upper critical magnetic field. The results are presented here, with discussion for how they might point the way towards reaching even higher fields in Nb₃Sn cavities.

Poster MOPP019 [2.742 MB]

MOPP020

Input Couplers for Cornell ERL

linac, cryomodule, coupling, impedance

95

R.G. Eichhorn, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.A. Belomestnykh
BNL, Upton, Long Island, New York, USA

Cornell has developed two types of input couplers for the Energy Recovery Linac (ERL) Project. Both couplers are 1.3 GHz CW coaxial couplers. The coupler for ERL injector is a 65 kW CW coupler with variable coupling (Qext = 9*E4 to 9*E5). The coupler for ERL main linac is a 5 kW CW coupler with fixed coupling. It can be easily modified for variable coupling operation. Couplers have been tested on test stands and in cryomodules and showed good performance.

MOPP025

Longitudinal Beam Profile Measurements in Linac4 Commissioning

rfq, linac, electron, emittance

108

G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca
CERN, Geneva, Switzerland
M. Yarmohammadi Satri
IPM, Tehran, Iran

Linac4, the future 160 MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.

MOPP026

Actively Cooled RF Power Coupler : Theoretical and Experimental Studies

cryomodule, cryogenics, proton, linac

111

R. Bonomi, V. Parma
CERN, Geneva, Switzerland

In cryostats for Super-conducting Radio Frequency Cavities, the heat loads introduced by the high-power RF couplers represent an important fraction of the overall static thermal budget. Working at low operating temperature benefits from a reduced surface resistance (low dynamic losses) but is penalized by the high refrigeration cost. The external conductor of RF coaxial couplers provides a direct conduction path from ambient to cryogenic temperature plus is heated by resistive power deposition. Heat interception is therefore essential to contain heat in-leaks: a double-walled external conductor with a properly designed gas cooling effectively reduces heat loads to the cold bath by 1 order of magnitude. This paper presents the thermal design of the RF power coupler of the Superconducting Proton Linac (SPL) at CERN, featuring a helium vapour cooling between 4.5 K and ambient temperature. Numerical models, which can be used as design tools for other applications, have been developed to assess efficiency and thermal performance. A full-size mock-up cooled by nitrogen has been built for experimental validation. Comparison between calculations and measurements is presented and discussed.

MOPP029

Overview of the New High Level Software Applications Developed for the HIE-ISOLDE Superconducting Linac

controls, linac, software, pick-up

117

D. Lanaia, M.A. Fraser, D. Voulot
CERN, Geneva, Switzerland

The High Intensity and Energy (HIE) ISOLDE project consists of an upgrade of the ISOLDE facility. With the installation of 32 independently-phased, superconducting quarter-wave cavities the energy of post-accelerated radioactive beams will be increased from 3 MeV/u to over 10 MeV/u. The large number of cavities will increase the number of parameters to optimise. In order to ensure a fast set-up of the machine during operation and commissioning, new software applications have been developed and an upgrade of the existing software was carried out. Four high level applications have been specifically developed for the SC linac. The first allows the conversion of optics settings into machine settings, and vice versa. The second will aid the phasing of the cavities using beam energy measurements. A third application will provide absolute measurements of the beam energy by means of a time-of-flight system. The last application will automatically generate the phase and voltage settings for the cavities SC linac. In this contribution we will present the new applications and outline how these will be used in the operation of the new SC linac.

Poster MOPP029 [1.568 MB]

MOPP034

Beam Dynamics Studies of the CLIC Drive Beam Injector

bunching, emittance, focusing, quadrupole

131

S. Sanaye Hajari, S. Döbert, H. Shaker
CERN, Geneva, Switzerland
S. Sanaye Hajari, H. Shaker
IPM, Tehran, Iran

In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel with the main linac. The beam in the Drive Beam Accelerator is phase coded. This means only every second accelerator bucket is occupied. However, a few percent of particles are captured in wrong buckets, called satellite bunches. The phase coding is done via a sub-harmonic bunching system operating at a half the acceleration frequency. The beam dynamics of the Drive Beam injector complex has been studied in detail and optimised. The model consists of a thermionic gun, the bunching system followed by some accelerating structures and a magnetic chicane. The bunching system contains three sub-harmonic bunchers, a prebuncher and a tapered travelling wave buncher all embedded in a solenoidal magnetic field. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimising the overall bunching process and in particular decreasing the satellite population and the beam loss in magnetic chicane and in transverse plane limiting the beam emittance growth.

MOPP035

Bead-Pull Measurement Method and Tuning of a Prototype CLIC Crab Cavity

electromagnetic-fields, coupling, simulation, extraction

134

R. Wegner, W. Wuensch
CERN, Geneva, Switzerland
G. Burt, B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

A bead-pull method has been developed which measures in a single bead passage the amplitude and phase advance of deflecting mode travelling wave structures. This bead-pull method has been applied to measure and tune a Lancaster University-designed prototype crab cavity for CLIC. The technique and tuning results are described.

MOPP037

Conceptual Design of the ESS DTL Faraday Cup

DTL, simulation, linac, beam-transport

140

B. Cheymol, E. Lundh
ESS, Lund, Sweden

The DTL section of the ESS linac will accelerate the beam form 3.6 MeV to 90 MeV at a peak current of 62.5 mA. It is foreseen to install after each DTL tank a Faraday cup for beam current and the beam transmission measurements during retuning phase. An energy degrader will be positioned in front of the in order to perform a low resolution phase scan of the DTL tank before injecting the beam in the downstream structure. This paper describes the preliminary studies of the Faraday cup, mainly focus on the energy degrader.

MOPP040

Application Investigation of High Precision Measurement for Basic Cavity Parameters at ESS

controls, operation, beam-loading, injection

149

R. Zeng
ESS, Lund, Sweden
P. Jonsson
Lund University, Lund, Sweden
W. Schappert
Fermilab, Batavia, Illinois, USA

The ESS cavity control and operation methods/algorithms are challenging due to the use of long pulse, higher beam intensity, high beam power, high gradient, uncertainties in spoke cavities and high demands for energy efficiency and availability. Suitable and effective solutions could make use of modern technologies (flexible FPGA, faster CPU, bigger memory, faster communication speed), novel measuring techniques, accurate system modeling, and advanced control concept. Those possible implementations are essential to a better understanding, and thus a better operation of ESS cavity especially SRF cavities. All these concepts rely on high precision measurement of basic cavity parameters and consequent high quality data with high resolution, high precision and completeness. This paper focuses on how high precision measurement will address the challenges at ESS on the following topics: long pulse lorentz force detuning, high precision phase and amplitude setting, heavy beam loading compensation and power overhead reduction.

MOPP044

MSU RE-Accelerator ReA3 0.085 QWR Cryomodule Status

cryomodule, solenoid, alignment, linac

155

T. Xu, B. Bird, F. Casagrande, J.L. Crisp, K.D. Davidson, C. Dudley, A. Facco, P.E. Gibson, I. Grender, L. Hodges, K. Holland, M.J. Johnson, S. Jones, B. Laumer, D. Leitner, A. Mccartney, S.J. Miller, D. Morris, S. Nash, J.P. Ozelis, J. Popielarski, L. Popielarski, R. Rosas, R.J. Rose, K. Saito, M. Thrush, R. Walker, J. Wei, W. Wittmer, Y. Xu
FRIB, East Lansing, Michigan, USA
B. Arend, J. Ottarson, D.P. Sanderson, D. Wahlquist, J. Wenstrom
NSCL, East Lansing, Michigan, USA
M. Leitner
LBNL, Berkeley, California, USA

ReA3 β=0.085 QWR cryomodule is the third cryomodule for the superconducting LINAC of ReA3 reaccelerated beam facility, which will bring the maximum beam energy to 3 MeV/u for heavy ions. This cryomodule consists of 8 β=0.085 QWR cavities and 3 9T superconducting solenoids and operates at 4K. Qualification of cavities and FPCs and the construction of cold mass was completed in 2013. The installation of the module was completed this summer. Functioning not only as an important part of the ReA3 facility, cryomodule 3 also serves as a test bed for FRIB driver Linac and demonstrated the technology needed for FRIB CMs. Here we report the construction, installation and testing of the β=0.085 cryomodule and the development of the critical components.
Project funded by Michigan State University

MOPP046

On the Design of Higher Order Mode Antenna for LCLS II

HOM, coupling, higher-order-mode, simulation

161

M.H. Awida, I.V. Gonin, T.N. Khabiboulline, K.S. Premo, O.V. Pronitchev, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
The upgrade of the Linac Coherent Light Source (LCLS-II) necessitates a major modification to the higher order mode (HOM) antenna of the conventional ILC elliptical 9-cell cavity. Due to the continuous wave nature of the proposed LCLS II Linac, the HOM antenna is required to bare higher RF losses. A modified design of the HOM antenna is presented in this paper ahead with a thorough thermal quench study in comparison with the conventional ILC design.

MOPP049

Dipole Kick due to Geometry Asymmetries in HWR for PXIE

dipole, multipole, linac, cryomodule

165

P. Berrutti, T.N. Khabiboulline, V.A. Lebedev, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by D.O.E. Contract No. DE-AC02-07CH11359
Project X Injector Experiment (PXIE) will have a family of half wave resonators having frequency=162.5 MHz and beta optimal=0.11. During cavity production, when the niobium parts are assembled and welded together, it is fundamental to control the frequency of the accelerating mode in order to meet the specified operating value. For the HWR of PXIE the tuning will be achieved by trimming one end of the resonator only, this will introduce unwanted asymmetry in the cavity geometry leading to a dipole kick for the particles traveling through the cavity. The cavity geometry will be different from the ideal, once the cavity is assembled, because of small misalignment of the niobium parts and because of the welding shrinkage. Misalignments of the inner conductor and the beam pipes can be expected. The asymmetry due to tuning process along with production misalignments, have been simulated and the equivalent dipole kick has been calculated.

Poster MOPP049 [1.441 MB]

MOPP052

Development of 5-Cell β=0.9 650 MHz Elliptical Cavities for Project X

linac, HOM, coupling, accelerating-gradient

171

I.V. Gonin, M.H. Awida, M.H. Foley, A. Grassellino, C.J. Grimm, T.N. Khabiboulline, A. Lunin, A.M. Rowe, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Several 5-cell 650 MHz elliptical cavities have been fabricated for the PIP-II Project. Two versions of the cavities have been designed to accelerate protons of relative group velocity of β=0.9 and β=0.92 in the high energy region of the linac. In this paper, we report the development status of these cavities, summarize the results of the quality control measurements performed on five initial prototypes, and outline the VTS test results.

MOPP054

Continuous-Wave Horizontal Tests of Dressed 1.3 GHz SRF Cavities for LCLS-II

HOM, controls, SRF, linac

177

A. Hocker, A.C. Crawford, M. Geynisman, J.P. Holzbauer, A. Lunin, D.A. Sergatskov, N. Solyak, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359
Fermilab’s Horizontal Test Stand has recently been upgraded to provide CW RF testing capabilities in support of the LCLS-II project at SLAC. Several cavities have been tested in this new configuration in order to validate component designs and processes for meeting the requirements of LCLS-II. Areas of study included gradient and Q0 performance and their dependence on extrinsic factors, thermal performance of the input coupler and HOM feedthroughs, and microphonics and RF control. A description of the testing and the results obtained are presented.

Poster MOPP054 [0.276 MB]

MOPP055

RF Tests of Dressed 325 MHz Single-Spoke Resonators at 2 K

network, operation, LLRF, resonance

180

A. Hocker, E. Cullerton, B.M. Hanna, W. Schappert, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Funding: United States Department of Energy, Contract No.DE- AC02-07CH11359
Fermilab has recently completed an upgrade to its spoke resonator test cryostat to enable testing of cavities in superfluid helium. Two single-spoke resonators with differing helium vessel designs have been tested in this new configuration. Gradient and Q0 performance was studied along with microphonics control and sensitivity of the resonant frequency to pressure variations. A description of the testing and the results obtained are presented.

Poster MOPP055 [0.437 MB]

MOPP058

Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac

electron, laser, radiation, dipole

183

J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
W.B. Wortley
University of Rochester, Rochester, New York, USA

Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP059

Study and Design of the High Power RF Coupler for the CH-Cavity of the Fair pLINAC

coupling, proton, linac, resonance

187

F. Maimone, G. Clemente, W. Vinzenz
GSI, Darmstadt, Germany

At GSI a proton Linac has been designed and developed in order to provide a 70 MeV proton beam for the FAIR facility. The pLINAC consists of an RFQ followed by six CH-DTL accelerating cavities and the electromagnetic field inside each cavity is generated by seven Klystrons providing up to 2.8 MW power at 325.224 MHz. The high power RF coupling between the Klystron and the accelerating CH-cavity has been studied and an inductive coupling loop has been designed. The coupler insertion inside the cavity and the rotation angle with respect to the magnetic field lines have been adjusted and the results of the analysis of the coupler positioning are presented. A prototype coupler is under construction and the measurement of RF coupling with the CH-cavity is scheduled within this year.

MOPP061

First RF Measurements of the Superconducting 217 MHz CH Cavity for the CW Demonstrator at GSI

simulation, linac, status, ion

193

F.D. Dziuba, M. Amberg, M. Basten, M. Busch, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher, W.A. Barth, S. Mickat
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: Work supported by GSI, HIM, BMBF Contr. No. 05P12RFRBL
Presently, a superconducting (sc) 217 MHz Crossbar-Hmode (CH) cavity is under construction at Research Instruments (RI), Bergisch Gladbach, Germany. Among the horizontal cryomodule and two sc 9.5 T solenoids the cavity is the key component of the cw demonstrator at GSI. To show the operation ability of sc CH cavity technology under a realistic linear accelerator environment is one major goal of the demonstrator project. A successful beam operation of the demonstrator will be a milestone regarding the continuing advanced sc cw linac project at GSI for a competitive production of Super Heavy Elements (SHE) in the future. The fabrication status as well as first rf measurements at room temperature of the 217 MHz CH cavity are presented.

Poster MOPP061 [1.741 MB]

MOPP062

Proposal of a Conventional Matching Section as an Alternative to the Existing HSI MEBT Superlens at GSI UNILAC

DTL, simulation, rfq, emittance

196

H. Hähnel, U. Ratzinger, R. Tiede
IAP, Frankfurt am Main, Germany

We propose a new design for the HSI MEBT section at GSI UNILAC as part of the planned UNILAC upgrade. The existing MEBT section was designed in 1996 and based on a novel concept called the superlens* which uses a magnetic quadrupol doublet lens combined with a short RFQ cavity for transversal and longitudinal focusing. In 2009 the RFQ section in front of the MEBT was upgraded which led to significant changes in the RFQ output particle distribution. Recent LORASR simulations show that the superlens transmission decreases to 90% (related to 20.75 mA, U⁴⁺ at input). Moreover, the matching to the following IH-DTL is not ideal. This leads to further losses in the IH and to a decrease of the overall UNILAC efficiency. To reach the FAIR requirement of 18 mA U⁴⁺ current for the UNILAC with minimal losses and to provide more flexibility for varying current level operation, a new design based on two magnetic quadrupole triplet lenses and a 2-gap buncher is proposed. The design shows full transmission at 20.75 mA U⁴⁺ current and improved matching to the IH-DTL, leading to a drastic decrease of particle losses along the IH-DTL.
* U. Ratzinger, R. Tiede, A New Matcher Type between RFQ and IH-DTL for the GSI High Current Heavy Ion Prestripper LINAC, Proc. LINAC96, Geneva, Switzerland, pp. 128-130

Poster MOPP062 [9.440 MB]

MOPP064

R&D of the 17 MeV MYRRHA Injector

emittance, proton, rfq, linac

202

D. Mäder, M. Basten, D. Koser, H.C. Lenz, N.F. Petry, H. Podlech, A. Schempp, M. Schwarz, M. Vossberg
IAP, Frankfurt am Main, Germany
C. Zhang
GSI, Darmstadt, Germany

Funding: Project supported by the EU, FP7 MAX, Contract No. 269565
MYRRHA is designed as an accelerator driven system (ADS) for transmutation of long-lived radioactive waste. The challenge of the linac development is the very high reliability of the accelerator to limit the thermal stress inside the reactor. With the concept of parallel redundancy the injector will supply a cw proton beam with 4 mA and 17 MeV to the main linac. The new MYRRHA injector layout consists of a very robust beam dynamics design with low emittance growth rates. Sufficient drift space provides plenty room for diagnostic elements and increases the mountability. Behind a 4-Rod-RFQ and a pair of two-gap QWR rebunchers at 1.5 MeV the protons are matched into the CH cavity section. A focussing triplet between the rebunchers ensures an ideal transversal matching into the doublet lattice. Each of the 7 RT CH structures has a constant phase profile and does not exceed thermal losses of 29 kW/m. The transition to the 5 SC CH cavities with constant beta profile is at 5.9 MeV. For a safe operation of the niobium resonators the electric and magnetic peak fields are defined below 25 MV/m and 57 mT respectively.

Poster MOPP064 [4.024 MB]

MOPP066

High Gradient CH-Type Cavity Development for 10 – 100 AMeV Beams

linac, quadrupole, ion, heavy-ion

208

A. Almomani, U. Ratzinger
IAP, Frankfurt am Main, Germany

Funding: This work is supported by Federal Ministry of Education and Research - BMBF No. 05P12RFRB9.
The development in pulsed linac activities aims on compact designs and on an increase of the voltage gain per meter. At IAP - Frankfurt, a CH design was developed for these studies, where the mean effective accelerating field is expected to reach well above 10 MV/m at 325 MHz, β=0.164. Within a funded project, this cavity is systematically developed. Currently, the cavity is under construction at NTG GmbH and expected to be ready for copper plating in autumn 2014. The results should give an impact on the rebuilt of the UNILAC - Alvarez section, optimized for achieving the beam intensities specified for the GSI – FAIR project. A mid- and long- term aim is a compact pulsed high current linac. The new GSI 3 MW Thales klystron test stand will be very important for these investigations. Detailed studies on two different types of copper plating can be performed on this cavity. Additionally, operating of normal conducting cavities at cryogenic temperatures will be discussed. In this work, the cavity status will be presented.

MOPP068

The Fast Piezo-Based Frequency Tuner for SC CH-Cavities

resonance, laser, simulation, operation

214

M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, V. Gettmann, S. Mickat
GSI, Darmstadt, Germany

Funding: Work supported by HIM, GSI, BMBF Contr. No 05P12RFRBL
Superconducting structures are very susceptible to external influences due to their thin walls and their narrow bandwidth. Even small mechanical deformations caused by dynamic effects like microphonic noise, pressure fluctuations of the liquid helium bath or Lorentz-Force-Detuning can lead to resonance frequency changes of the cavity which are much larger than the bandwidth. To compensate the slow and fast resonance frequency variations during operation a compact frequency tuner prototype equipped with a stepper motor and a piezo actuator has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. In this paper, the tuner design and the results of first room temperature measurements of the tuner prototype are presented.

Poster MOPP068 [2.304 MB]

MOPP070

Final Design for the BERLinPro Main Linac Cavity

HOM, linac, emittance, dipole

217

A. Neumann, J. Knobloch
HZB, Berlin, Germany
K. Brackebusch, T. Flisgen, T. Galek, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
B. Riemann, T. Weis
DELTA, Dortmund, Germany

Funding: This work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC
The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities based on a modified Cornell ERL design combined with JLab's waveguide HOM damping approach. This paper will summarize the final optimization of the end-cell tuning for minimum external Q of the HOMs, coupler kick calculations of the single TTF fundamental power coupler as well as multipole expansion analysis of the given modes and a discussion on operational aspects.

Poster MOPP070 [1.561 MB]

MOPP071

BESSY VSR 1.5 GHz Cavity Design and Considerations on Waveguide Damping

damping, HOM, SRF, operation

221

A.V. Velez, J. Knobloch, A. Neumann
HZB, Berlin, Germany

The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.5ps) bunches in the storage ring with the present user optics. To this end, new high-voltage L-Band superconducting multi-cell cavities must be installed in one of the straights of the ring. These 1.5 GHz and 1.75 GHz cavities are based on 1.3 GHz systems being developed for the BERLinPro energy-recovery linac. This paper describes the baseline electromagnetic design of the first 5-cell cavity operating at 1.5 GHz.

Poster MOPP071 [1.088 MB]

MOPP074

Digital Filters Used for Digital Feedback System at cERL

LLRF, controls, feedback, operation

227

F. Qiu, D.A. Arakawa, H. Katagiri, H. Matsumoto, S. Michizono, T. Miura
KEK, Ibaraki, Japan

As a test facility for the future KEK 3-GeV energy recovery linac (ERL) project, the compact ERL (cERL) features three two-cell cavities for the injector and two nine-cell cavities for the main linac. Digital low-level radio frequency (LLRF) systems have been developed to realize highly accurate RF control. In order to reduce the influence of clock jitter and to suppress the parasitic modes in the multi-cell cavities, we have developed several types of digital filters, including a first-order IIR filter, a fourth-order conjugate poles IIR filter and a notch filter. Furthermore, to design a more effective and robust controller (such as an H-infinite controller, or repetitive controller), we need to acquire more detailed system knowledge. This knowledge can be gained by using modern system identification methods. In this paper, we present the latest applications in the LLRF systems of the cERL. identification methods. In this paper, we have compared the performance of these different type filters in cERL. The preliminary result of the system identification will be also described.

MOPP078

RF Power Systems for the FAIR Proton Linac

klystron, linac, proton, electronics

236

J. Lesrel, C. Joly
IPN, Orsay, France
E. Plechov, A. Schnase, G. Schreiber, W. Vinzenz
GSI, Darmstadt, Germany

In the framework of collaboration between the FAIR project, GSI, and CNRS, the IPNO lab is in charge of providing the high power RF components for a cavity test stand and for the planned FAIR proton Linac. This Linac will be connected to the existing GSI synchrotron SIS18 for serving as an injector for the new FAIR facility. The 70 MeV FAIR proton Linac design contains a 3 MeV RFQ, and a DTL based on Cross-bar H-mode cavities (CH). It will operate with pulsed RF at 325.224 MHz with a width of 200 μs and a repetition rate of 4 Hz. The planned RF systems of the proton Linac will be presented as well as the description of the test stand. The first power test results are obtained with a Thales klystron developed jointly with CNRS. Three solid state amplifiers made by Sigmaphi Electronics for the bunchers will also be described in this paper.

MOPP081

The ECT System for RAON's Cavities

SRF, experiment, niobium, controls

242

M.J. Joung, Y. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea

The ECT system is in use for Nb surface control in many laboratories. This system can inspect Nb surface quickly using high resolution. The ECT system for RAON's cavity was made with the feature : It has 3-axis acting probe movement system, It can inspect big size of Nb sheet, which is 1m by 1m and It contain the analysis program that can show the result as 2D and 3D image as well as relative figure of surface level. The standard sample was made with various sizes of defects using the same Nb sheet that was used to make RISP cavity. The ECT system conditioining was carried out to optimize ECT operation on the frequency, the range is from 300kHz to 2MHz. The result of 900 kHz shows the strongest signal. The conditioning experiment on other parameter will be carried out in near future. .

MOPP082

Superconducting Linac for RISP

linac, cryomodule, ion, quadrupole

245

H.J. Kim, H.J. Cha, M.O. Hyun, H.C. Jung, Y.J.K. Kim, M. Lee
IBS, Daejeon, Republic of Korea

The RISP (Rare Isotope Science Project) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. It can deliver ions from proton to Uranium. Proton and Uranium beams are accelerated upto 600 MeV and 200 MeV/u respectively. The facility consists of three superconducting linacs of which superconducting cavities are independently phased. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the RISP linac design, the prototyping of superconducting cavity and cryomodule.

MOPP090

Adjustment of the Coupling Factor of the Input Coupler of the ACS Linac by a Capacitive Iris in J-PARC

coupling, simulation, linac, ion

264

J. Tamura, H. Ao, K. Hirano, Y. Nemoto, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
H. Asano
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
F. Naito, K. Takata
KEK, Ibaraki, Japan

Annular-ring Coupled Structure (ACS) cavities have been installed to increase the beam energy of the Japan Proton Accelerator Research Complex (J-PARC) linac from 181 to 400 MeV in the maintenance period of 2013. Some of the pillbox type input couplers with a ceramic window to the ACS cavity have a larger coupling factor than the target value by an avoidable manufacturing error. To adjust the coupling factor, a capacitive iris was introduced in the rectangular waveguide near the coupler. As a result, it has been confirmed that the iris decreases the coupling factor to a target value without any significant increase in temperature and in a discharge rate during high-power operation. In this paper, the design procedure of the capacitive iris and the result of the coupling factor adjustment are presented.

MOPP093

Evaluation of Beam Energy Fluctuations Caused by Phase Noises

linac, experiment, timing, electron

273

H. Hanaki, H. Dewa, S. Suzuki, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan
T. Asaka, T. Ohshima
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results.

MOPP099

Compact Proton Injector for Synchrotrons

rfq, linac, proton, quadrupole

291

A.D. Kovalenko, A.V. Butenko
JINR, Dubna, Moscow Region, Russia
A. Kolomiets, A.S. Plastun
ITEP, Moscow, Russia

Compact linac comprising two sections of different RFQ structures was designed. The first section is conventional RFQ with output energy 3 MeV whereas the second one is RFQ with trapezoidal modulation of vanes. The linac output energy is 8 MeV. The both structures operate at frequency of 352 MHz. The total length of machine is less than 8 m. The output pulsed beam current is of 40 mA. The design is suitable for both as NICA injection complex and proton superconducting medical synchrotron.

MOPP101

Design of the 4MeV RFQ for the Helium Beam Irradiatior

rfq, controls, ion, ion-source

294

H.-J. Kwon, Y.-S. Cho, H.S. Kim, K.T. Seol, Y.-G. Song
KAERI, Daejon, Republic of Korea

Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government.
A RFQ is considered as a main accelerator of the helium beam irradiation system for the power semiconductor in Korea Multipurpose Accelerator Complex (KOMAC). The RFQ was designed to accelerate the He²⁺ beam up 4MeV with 10mA peak beam current. We chose a vane type RFQ with 200MHz operating frequency. The RFQ will be operated with the frequency tracking mode supplied by the digital low level rf control system. In this paper, the design of the 4MeV RFQ is presented and the beam irradiation system including rf system, control system, utility system, is discussed.

MOPP103

Fault Tolerance and Consequences in the MYRRHA Superconducting Linac

linac, operation, cryomodule, simulation

297

F. Bouly
LPSC, Grenoble Cedex, France
J.-L. Biarrotte
IPN, Orsay, France
D. Uriot
CEA/DSM/IRFU, France

Funding: This work is being supported by the European Atomic Energy Community’s EURATOM) Seventh Framework Programme under grant agreement n°269565(MAX project).
The MYRRHA project aims at the construction of new irradiation complex in Mol (Belgium) to demonstrate the transmutation feasibility with an Accelerator Driven System (ADS). In its subcritical configuration, the MYRRHA facility requires a proton flux with a maximum power of 2.4 MW (600 MeV - 4 mA). Such a continuous wave beam will be delivered by a superconducting linac which must fulfil very stringent reliability requirements to ensure the safe ADS operation with a high level of availability. In this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid failures mitigations. Beam dynamics studies on the fault tolerance capability of the MYRRHA superconducting linac will be presented. The results will be mainly focused on RF failure compensation scenarios: when one or several superconducting cavities are lost in the linac. The impact on the R&D to enable fast retuning procedures in the linac will also be discussed.

MOPP107

Results from the Installation of a New 201 MHz RF System at LANSCE

DTL, electronics, controls, linac

303

J.T.M. Lyles, C.L. Arnold, W.C. Barkley, J. Davis, A.C. Naranjo, M.S. Prokop, D. Rees, G. M. Sandoval, Jr.
LANL, Los Alamos, New Mexico, USA
D. Baca, R.E. Bratton, R.D. Summers
Compa Industries, Inc., Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
The LANSCE RM project is restoring the linac to it’s original high power capability after the power grid tube manufacturer could no longer provide triodes that could consistently meet our power requirements. High duty factor Diacrodes® now supply RF power to the largest DTL tank. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. The power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce as much as 3.5 MW peak and 420 kW of mean power. A digital low level RF control system was developed to complement these new linear amplifiers. Design and testing was completed in 2012, with commercialization following in 2013. The first installation is commissioned. The two remaining high power RF systems for tanks 3 and 4 will be replaced in subsequent years using a hybrid old/new RF system until the changeover is complete. Features and operating results of the replacement system are summarized, along with observations from the rapid-paced installation project.

MOPP108

Vertical Electro-Polishing of Nb Nine-Cell Cavity Using Cathode with Variable-Geometry Wings

cathode, experiment, power-supply, status

307

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
K. Ishimi
MGI, Chiba, Japan

Marui Galvanizing Co. Ltd. has been studying on Vertical Electro-Polishing (VEP) of Nb superconducting accelerator cavity for the mass-production and cost-reduction of Electro-Polishing (EP) process in collaboration with KEK. And we invented VEP process by a cathode with variable-geometry wings to get uniform distributions of both electric current and EP solution flow. Using this cathode, we performed various tests of VEP with Nb single-cell cavities. In this article, we will report fabrication of the first VEP facility for Nb nine-cell cavity and the VEP results using cathode with variable-geometry wings.

MOPP110

Multipacting Prediction for the 10⁶.1 MHz Quarter Wave Resonator

simulation, ISAC, experiment, electron

313

M. Gusarova, I.I. Petrushina, E.A. Savin, A.N. Stolbikova
MEPhI, Moscow, Russia
V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

The results of analytical calculations and numerical simulations of multipacting in the 10⁶.1 MHz Quarter Wave Resonator (QWR) are presented. Resonant voltages, impact energies and corresponding particle trajectories are obtained. In this paper we compare CST PS and MultP-M 3D simulation results for multipacting in the cavity.

MOPP114

SNS Linac Upgrade Plans for the Second Target Station

linac, cryomodule, klystron, rfq

320

J. Galambos, D.E. Anderson, M.P. Howell, S.-H. Kim, M.A. Plum, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The Second Target Station (STS) upgrade for the Spallation Neutron Source (SNS) proposes the addition of a short pulse, long wavelength neutron scattering station. In order to provide world-class intensity at the additional station, the SNS linac beam power capability is doubled, to 2.8 MW. This will be accommodated by a 30% increase in the beam energy to 1.3 GeV and a 50% increase in beam current. The beam energy increase will be provided by the addition of 7 additional cyro-modules and supporting RF equipment in space provided during the original SNS construction. The beam current increase will be provided by improved ion source and a reduced chopping fraction, and will require increases in the RF and high voltage modulator systems to accommodate the additional beam loading. Initial plans will be presented. The proposed linac upgrade path will be described.

MOPP115

Plasma Processing of Nb Surfaces for SRF Cavities

plasma, SRF, accelerating-gradient, vacuum

323

P.V. Tyagi, M. Doleans, S.-H. Kim
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, C.J. McMahan
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Field emission is one of the most critical issues to achieve high performances of niobium (Nb) superconducting radio frequency (SRF) cavities. Field emission is mainly related to contaminants present at top surface of SRF cavities that act as electron emitters at high gradient operation and limit the cavity accelerating gradient. An R&D program at the Spallation Neutron Source (SNS) is in place* aiming to develop an in-situ plasma processing technique to remove some of the residual contaminants from inner surfaces of Nb cavities and improve their performance. The plasma processing R&D has first concentrated on removing hydrocarbon contamination from top surface of SRF cavities. Results from the surface studies on plasma processed Nb samples will be presented in this article and showed the removal of hydrocarbons from Nb surfaces as well as improvement of the surface workfuntion (WF).
*M. Doleans et al. “Plasma processing R&D for the SNS superconducting linac RF cavities” Proceedings of 2013 SRF workshop, Paris, France

Slides MOPP115 [1.405 MB]

MOPP117

Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole

dipole, multipole, survey, emittance

326

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

MOPP118

C-Band Load Development for the High Power Test of the SwissFEL RF Pulse Compressor

impedance, klystron, vacuum, coupling

329

A. Citterio, J. Stettler, R. Zennaro
PSI, Villigen PSI, Switzerland

The SwissFEL C-band Linac will have 26 RF modules, each one consisting of a solid-state modulator and a 50 MW klystron that feeds a pulse compressor and four two meters long accelerating structures. The pulse compressor is of the Barrel Open Cavity type (BOC). A first prototype was successfully produced and high-power tested, reaching for full power klystron operation a peak power of 300 MW. For testing this BOC at maximum RF power, a broadband load was designed and built, based on a ridge waveguide design and high permeability stainless steel. Based on the experience gained at CERN for CLIC X-band high power loads, the RF design of the load was optimized to ensure high losses for a quite large range of magnetic steels. Test pieces were realized in three different magnetic steels to choose the best suited material commercially available. This paper reports about the RF design, material study, production and impressive high power results of this C-band load.

MOPP123

Development Activities of Accelerator Instruments for SACLA

controls, acceleration, klystron, laser

342

Y. Otake, T. Asaka, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Ego, S. Matsubara
JASRI/SPring-8, Hyogo-ken, Japan

The X-ray free-electron laser, SACLA, is constantly operated for user experiments aimed at new science. Experimental users demand further experimental abilities, such as many experimental chances by using multi-X-ray beam lines, much better repeatability of the experiment conditions and further intense high-energy X-rays. To equip SACLA with these abilities in the future, we have developed a 2pi /3 CG acceleration structure with an acceleration gradient of over 45 MV/m to adapt operation for generating the intense high-energy X-rays. A high-voltage power supply to charge the PFN of a modulator, a klystron and an acceleration structure were developed to adapt operation for 120 pps operation from the present 30 pps, since 120 pps is more suitable for beam distribution to the multi-beam lines. To meet the experimental repeatability realized by stable timing in a pump-probe experiment, an optical-fiber length control system to mitigate timing drift below 1 fs for 10 minutes was developed. Highly precise cavity temperature control system in an injector for below ±2mK was also realized. Performances of our developed instruments were experimentally tested to be sufficient for our demands.

MOPP126

Untrapped HOM Radiation Absorption in the LCLS-II Cryomodules

HOM, cryomodule, impedance, linac

351

K.L.F. Bane, C. Adolphsen, C.D. Nantista, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
A. Saini, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
The superconducting cavities in the continuous wave (CW) linacs of LCLS-II are designed to operate at 2 K, where cooling costs are very expensive. One source of heat is presented by the higher order mode (HOM) power deposited by the beam. Due to the very short bunch length-especially in L3 the final linac-the LCLS-II beam spectrum extends into the terahertz range. Ceramic absorbers, at 70 K and located between cryomodules, are meant to absorb much of this power. In this report we perform two kinds of calculations to estimate the effectiveness of the absorbers and the amount of beam power that needs to be removed at 2 K.

MOPP130

A Linac-Based Approach to Modelling an Orbit Separated Cyclotron

linac, cyclotron, simulation, emittance

364

D.C. Plostinar, G.H. Rees
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

An orbit separated cyclotron (OSC) is a new type of accelerator intended as a proton driver for Accelerator Driven Subcritical Reactors (ADSRs). A ring has been designed based on the new concept that accelerates a proton beam from 500 MeV to 1 GeV in four turns using multi-cell superconducting cavities in each period. From a beam dynamics point of view, the ring can be considered as a “wrapped-up” linac at four times the ring circumference. In this paper we present beam dynamics modelling details when using 3D linac codes and cavity field maps. We conclude that the versatility of codes such as TraceWin, allows detailed machine modelling and improved design procedures that take into account various aspects including orbit distortion caused by transverse deflecting fields in the cavities.

MOPP132

Development of a Micro-Pulse Electron Gun Based Upon pi-Mode Dual-Cavity

electron, gun, cathode, simulation

367

L. Liao, Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

The concept of a novel micro-pulse electron gun (MPG) based upon pi-mode dual-cavity is proposed and analyzed in this paper, and we termed it as dual-cavity micro-pulse electron gun (D-MPG) as compared to single-cavity standard MPG. From simulations, it is clear that the D-MPG is capable of yielding dozens of ampere peak currents and a few ps bunch length. Thought the mechanism for dual cavity is not fully understand, the D-MPG has demonstrate the potential to be the injectors for FEL and THz radiation facilities. Also it is a good candidate to replace the thermal cathode for industrial and medical accelerator system because of the cost-effective of the D-MPG.

MOPP133

Measurements of Cavity Misalignment by Beam Induced HOM Excited in 9-cell Superconducting Cavities

HOM, simulation, dipole, experiment

370

A. Kuramoto
Sokendai, Ibaraki, Japan
N. Baboi
DESY, Hamburg, Germany
H. Hayano
KEK, Ibaraki, Japan

Detection of cavity misalignment in the ILC superconducting cavities inside of the cryomodules can be done by using beam induced Higher Order Modes (HOM). It is beneficial to identify possible source of emittance growth by cavity misalignment. Beam pipe modes which are localized in both ends of the cavity and TE111 1/9 pi mode which is localized in the center of the cavity are focused in this research. Deviations of these electrical centers from beam trajectory reference indicate cavity misalignment and bending. We measured beam-induced HOM in STF cavities of the STF accelerator at KEK in 2012 – 2013 and TESLA cavities of FLASH at DESY in 2013. We could identify beam pipe modes and TE111 1/9 pi mode in STF cavities and TESLA cavities at around 2.1 GHz and 1.6 GHz, both of which were very small signals. The electrical center of these beam pipe mode are studied by stretched wire method, beads perturbation method and simulations by CST MICROWAVE STUDIO 2012 and HFSS 12. In this paper, the results of these measurements and simulations are summarized.

MOPP134

Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening

proton, simulation, linac, vacuum

373

J. Rodnizki, Y. Ben Aliz, A. Grin, Z. Horvitz, A. Perry, L. Weissman
Soreq NRC, Yavne, Israel
G.K. Davis
JLab, Newport News, Virginia, USA
J.R. Delayen
ODU, Norfolk, Virginia, USA

The SARAF Prototype Superconducting Module (PSM) houses six 176 MHz Half Wave Resonators(HWR). The PSM accelerates protons and deuterons from 1.5 MeV/u to 4 and 5.6 MeV. The HWRs are highly sensitive to the coolant liquid Helium pressure fluctuations which limit the available beam power to 2kW per cavity out of 4kW RF amplifier and coupler and so might limit the available beam current to 2mA depending on the output energy. The flat shape of the cavity along the beam line in the area of the high electric field generates the high sensitivity of the Eigen mode frequency to helium pressure. The evaluated cavity sensitivity is full consistent with the measured values. It was explored that the tuning system (the fog structure) has a significant contribution to the cavity sensitivity. By using ribs or by modifying the rigidity of the fog we may reduce the HWR sensitivity by a factor of 3. This analysis is applied to study the stresses on the cavity during cool down and warm up to avoid plastic deformation as the Niobium yield is an order of magnitude lower in room temperature.

MOPP138

Fabrication and Measurements of 500 MHz Double Spoke Cavity

electron, simulation, radiation, target

385

H. Park, J.R. Delayen
JLab, Newport News, Virginia, USA
J.R. Delayen, C.S. Hopper, H. Park
ODU, Norfolk, Virginia, USA

The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.

Poster MOPP138 [2.144 MB]

TUIOA02

R&D Efforts for ERLs

linac, emittance, operation, SRF

394

R.G. Eichhorn
Cornell University, Ithaca, New York, USA

The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 10¹¹ in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.

Slides TUIOA02 [8.803 MB]

TUIOC01

Large Scale Testing of SRF Cavities and Modules

cryomodule, software, laser, vacuum

426

J. Świerbleski
IFJ-PAN, Kraków, Poland

Series production of SRF cavities, s.c. quadrupole packages and accelerator modules for the European XFEL is in full swing. Mid 2014 approx. 400 cavities will be tested, the testing of quadrupoles will be almost finished, and regular module testing will be established. Thus the talk should emphasize the quasi industrial testing of these components, of course including a good overview about the used somewhat unique AMTF infrastructure.

Slides TUIOC01 [3.094 MB]

TUIOC03

Nb3Sn - Present Status and Potential as an Alternative SRF Material

niobium, linac, SRF, cryogenics

431

S. Posen, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Nb₃Sn is a material that has the potential to have a transformative impact on SRF linacs. Due to its large critical temperature of approximately 18 K, Nb₃Sn cavities can have far smaller surface resistances at a given temperature than standard Nb cavities. This could significantly reduce the costs for infrastructure and power in cryoplants for large CW linacs. In addition, the predicted superheating field of Nb₃Sn is approximately double that of Nb, potentially doubling the maximum energy gradient. This would significantly decrease the size and cost of high energy linacs. In this work, we present recent progress in research and development for this promising material.

Slides TUIOC03 [3.357 MB]

Poster TUIOC03 [2.046 MB]

TUPP001

Cryogenic Performance of a New 72 MHz Quarter-Wave Resonator Cryomodule

cryomodule, cryogenics, solenoid, linac

437

Z.A. Conway, G.L. Cherry, R.L. Fischer, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, C.E. Peters, M.A. Power, T. Reid, J.R. Specht
ANL, Argonne, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
The Argonne National Laboratory ATLAS accelerator’s Intensity and Efficiency Upgrade project has been successfully finished [1]. This upgrade substantially increases beam currents for experimenters working with the existing stable and in-flight rare isotope beams and for the neutron rich beams from the Californium Rare Isotope Breeder upgrade. A major portion of this project involved the replacement of three existing cryomodules, containing 18 superconducting (SC) accelerator cavities and 9 superconducting solenoids, with a single cryomodule containing 7 SC 72.75 MHz accelerator cavities optimized for ion velocities of 7.7% the speed of light and 4 SC solenoids all operating at 4.5 K. This paper reports the measured thermal load to the 4 K and 80 K coolant streams and compares these results to the pre-upgrade cryogenic system.

TUPP002

Commissioning of the 72 MHz Quarter-Wave Cavity Cryomodule at ATLAS

cryomodule, SRF, ion, operation

440

M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Hendricks, M. Kedzie, S.H. Kim, S.W.T. MacDonald, R.C. Murphy, P.N. Ostroumov, T. Reid, S.I. Sharamentov, G.P. Zinkann
ANL, Argonne, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
A cryomodule of seven 72 MHz SC quarter-wave cavities optimized for ions with v/c=0.077 has been commissioned in the ATLAS heavy-ion accelerator at Argonne. ATLAS has a new capability for increased beam currents with low beam losses for nuclear physics experiments using stable or rare isotope beams or neutron rich beams from the Californium Rare Isotope Breeder. The main goal for the cryomodule, to provide an accelerating voltage of 17.5 MV (2.5 MV/cavity), with no detectable beam losses has been met within the first month of commissioning. Thus far, cavities and primary subsystems including high-power couplers and pneumatic tuners are operating as designed with full availability. For present levels there is practically no field emission (EPEAK=40 MV/m) and RF losses of ~5 Watts/cavity are only half of that planned. Cavity fields will continue to be gradually increased, with the limits due to cavity quench measured at VACC=3.75 MV. Due to a combination of rf design and cavity processing, effective voltages are now 2 ½ times those for any other operational cavities for this v/c. We report here on the recent online test results and technical features of the present design.

TUPP003

4 K Alignment of Superconducting Quarter-Wave Cavities and 9 T Solenoids in the ATLAS Intensity Upgrade Cryomodule

target, cryomodule, solenoid, alignment

443

S.H. Kim, Z.A. Conway, W.G. Jansma, M. Kedzie, M.P. Kelly, P.N. Ostroumov
ANL, Argonne, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
The superconducting cavities and, especially, the magnets in high intensity ion linacs need to be aligned to the beam with typical transverse tolerances of 0.25 mm and 0.1 degrees at temperatures of 1.8 – 4.5 K. This is necessary to limit the emittance growth and minimize the beam losses. A new cryomodule with 7 superconducting quarter-wave resonators and 4 superconducting solenoids has been installed and is now operated at the Argonne Tandem Linear Accelerator System (ATLAS). We developed the techniques necessary to assemble the superconducting components in this cryomodule at room temperature so that they are aligned to the beam axis at 4.5 K. We achieved transverse alignment tolerances of <0.2 mm RMS. In this paper, we will present the details of the alignment hardware, procedures and results.

Slides TUPP003 [0.834 MB]

TUPP005

Completion of Efficiency and Intensity Upgrade of the ATLAS Facility

rfq, cryomodule, solenoid, ion

449

P.N. Ostroumov, Z.A. Conway, C. Dickerson, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, Y. Luo, S.W.T. MacDonald, R.C. Murphy, B. Mustapha, R.C. Pardo, T. Reid, S.I. Sharamentov, K.W. Shepard, J.R. Specht, G.P. Zinkann
ANL, Argonne, USA
A. Perry
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The ANL Physics Division has completed a major upgrade of the ATLAS National User Facility by successfully installing a new RFQ and cryomodule. The new normal conducting CW RFQ capable of providing 295 keV/u beams of any ion with m/q ≤7 from protons to uranium was fully integrated into ATLAS and has been in routine operation for more than a year. The RFQ doubled the efficiency of beam delivery to targets and opened the possibility to accelerate much higher intensity beams. Recently, the new cryomodule containing 7 high-performance 72.75 MHz superconducting quarter-wave resonators and 4 superconducting solenoids was successfully commissioned with beam. New design and fabrication techniques for these resonators resulted in record high voltages which were achieved during the beam commissioning. The new cryomodule provides 17.5 MV accelerating voltage which will be gradually raised by increasing the input RF power and improving LLRF system. The new cryomodule, which replaced 3 old cryomodules that used split-ring cavities, is also essential for high intensity stable beams. Results of beam commissioning and operation of ATLAS with the new RFQ and cryomodule will be presented.

TUPP006

Design of Relativistic Magnetron for High Power Microwave Generation

electron, simulation, extraction, cathode

452

R. Chandra, S.R. Ghodke, A.S. Patel, A. Sharma, S.K. Singh
BARC, Mumbai, India

A Linear Induction Accelerator based upon magnetic storage, utilising magnetic switches has been made and it is capable of providing a 400 kV diode voltage, 4 kA beam current for 100 ns pulse duration with 100 Hz repetition rate. It operates in a very high repetition rate due to the use of magnetic switches in it. The lesser shot to shot variation make this system ideal for a Relativistic Magnetron operation, where a huge dependence of output power on applied voltage and applied current is observed. A relativistic magnetron with axial extraction is analytically designed and simulated for this system. This relativistic magnetron is expected to give a power of 100 MW per pulse when operated in its full rating. The design features of this relativistic magnetron are presented here. This magnetron was designed for an output microwave frequency of 2.52 GHz.
*J. Benford, ''Space Applications of High-Power Microwaves'', IEEE Trans. Plasma Sci., vol. 36, no. 3, pp. 569–581, Jun. 2008

TUPP018

Analysis of Systematic and Random Error in SRF Material Parameter Calculations

simulation, extraction, SRF, niobium

465

S.J. Meyers, M. Liepe, S. Posen
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M. Liepe
Cornell University, Ithaca, New York, USA

Funding: NSF Career award PHY-0841213 and DOE award ER41628
To understand the relationship between an RF cavity’s performance and the material on its surface, one must look at various parameters, including energy gap, mean free path, and residual resistance. Though SRIMP fits for seven parameters, three parameters are eliminated using measurement and literature values, and the uncertainty of the fit of the remaining four parameters is further reduced by synthesizing two 3-parameter fits, each from a different data set. To study random error, Monte Carlo simulations were performed of ideal data with added noise; for systematic error, contour plots of normalized residual sum of squares (RSS) of the polymorphic fit on inputted data were generated.

Poster TUPP018 [1.183 MB]

TUPP019

Qualification of the Titanium Welds in the E-XFEL Cryomodule and the CE Certification

cryomodule, operation, linac, quadrupole

468

S. Barbanotti, H. Hintz, K. Jensch, R. Klos, W. Maschmann, A. Matheisen, A. Schmidt
DESY, Hamburg, Germany
C. Boulch, C. Cloué, C. Madec, J.L. Perrin, T. Trublet
CEA/IRFU, Gif-sur-Yvette, France
J.-P. Charrier, O. Napoly
CEA/DSM/IRFU, France

The CE stamping of the one hundred 1.3 GHz cryomodules for the XFEL Linac is a main step in the process of the certification of the entire Linac as a pressure equipment. Stringent requirements on materials and the quality of the welds of the pressurised components need to be satisfied to obtain the stamp. This paper summarizes these requirements, describes the process developed to qualify each module and summarises the rework campaign on the cavity helium vessels made necessary to obtain the required quality for a reliable and safe accelerator.

TUPP021

A New Type of Waveguide Distribution for the Accelerator Module Test Facility of the European XFEL

klystron, cryomodule, shielding, operation

475

V.V. Katalev, S. Choroba
DESY, Hamburg, Germany
E.M. Apostolov
MicroPlus-Apostolov Ltd., Sofia, Bulgaria
A.A. Seliverstov
s.p.a. FERRITE Ltd., St.Petersburg, Russia

In order to test 100 superconducting accelerator modules within two years three test benches have been created in the accelerator module test facility (AMTF) to achieve the rate of one cryomodule per week. Each RF station of the test facility consists of a 5 MW klystron, at 1.3 GHz, 1.37 ms pulse width and 10 Hz repetition rate, and a waveguide distribution system. Each waveguide distribution supplies RF power to eight cavities, four times a pair of cavities. The distribution allows for a maximum power of 1 MW per cavity when the distribution is switched to mode supplying power to only four cavities. A new type of 1 MW isolator and a new compact 5 MW power divider have been developed to achieve that goal. Several cryomodule have been already successfully tested with this setup. We present the waveguide distribution for this test stand and describe the performance of the different elements.

TUPP025

Progress on ESS Medium Energy Beam Transport

linac, quadrupole, rfq, DTL

484

I. Bustinduy, D. Fernandez-Cañoto, N. Garmendia, A. Ghiglino, O. González, P.J. González, Z. Izaola, I. Madariaga, M. Magan, L. Muguira, J.L. Muñoz, I. Rueda, F. Sordo, S. Varnasseri, R. Vivanco
ESS Bilbao, Bilbao, Spain
M. Eshraqi, R. Miyamoto, A. Ponton
ESS, Lund, Sweden

The considered versatile ESS MEBT is being designed to achieve four main goals: First, to contain a fast chopper and its correspondent beam dump, that could serve in the commissioning as well as in the ramp up phases. A detailed study of the chopper rise time effects on the loss budget will be presented. Second, to serve as a halo scraping section by means of various adjustable blades. Third, to measure the beam phase and proﬁle between the RFQ and the DTL, along with other beam monitors. And ﬁnally, to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of eleven quadrupoles is used to match the beam characteristics transversally, combined with three 352.2 MHz CCL type buncher cavities, which are used to adjust the beam in order to fulfil the required longitudinal parameters. A thorough study on the optimal input beam parameters will be discussed. Quadrupole design update will be presented along with new RF measurements over the buncher prototype. Finally, updated results will be presented on the chopper and beam-dump system.

Poster TUPP025 [5.596 MB]

TUPP031

Understanding the Error Tolerances Required to Automatically Phase the HIE-ISOLDE Linac

emittance, linac, software, experiment

496

M.A. Fraser, J.C. Broere, S. Haastrup, D. Lanaia, D. Valuch, D. Voulot
CERN, Geneva, Switzerland

The broad experimental programme at ISOLDE means that the same radioactive beam species and energy are rarely studied twice and the cavities of the linac must be scaled or re-phased for each experiment. A software application was developed to automatically re-phase the cavities of the HIE-ISOLDE superconducting linac to the beam from computed settings. The application was developed to expedite both machine set-up in normal operation and in scenarios involving cavity failures. A beam dynamics error study will be presented in order to better understand the challenges facing the automatic phasing routine. The effects of a variety of different errors on the efficacy of the phasing application were studied, leading to a specification of the tolerances required for the calibration of the rf system and the accuracy of the survey system that monitors the positions of the cavities.

TUPP043

Design of the Phase Reference Distribution System at ESS

controls, LLRF, radiation, linac

529

R. Zeng, H. Hassanzadegan, M. Jensen, J.M. Jurns, O.A. Persson, A. Sunesson
ESS, Lund, Sweden
K. Strniša
Cosylab, Ljubljana, Slovenia

PRDS (Phase reference distribution system) at ESS will provide phase reference signals for all LLRF systems and BPM systems with low phase noise and low phase drift. Phase stability requirement is currently 0.1° for short term (during pulse), 1° for long term (days to months). There are 155 LLRF systems and 165 BPM systems in total at current ESS accelerator design.

TUPP047

PXIE RFQ Bead Pull Measurements

rfq, beam-transport, quadrupole, experiment

535

P. Berrutti, T.N. Khabiboulline, V. Poloubotko, G.V. Romanov, J. Steimel, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
D. Li, J.W. Staples
LBNL, Berkeley, California, USA

Funding: Work supported by D.O.E. Contract No. DE-AC02-07CH11359
Project X Injector Experiment radio frequency quadrupole has recently been built for Fermilab by Berkley laboratory. This RFQ will be placed after the low energy beam transport (LEBT) and before the medium energy beam transport (MEBT). The RFQ will operate at 162.5 MHz in CW regime; its function is to accelerate and focus particles coming from the LEBT at 30 keV, and to deliver a beam at 2.1 MeV to the MEBT. In order to make sure that the RFQ meets the specifications of field flatness and frequency the field in the vanes should be measured using bead pull technique. FNAL created a new single wire bead pull set up for the RFQ of PXIE. The measurements are used to find the electrical center of the structure, then the amplitude of the electromagnetic field in all the sectors of the RFQ; and the tuning will be based on these measurements. This paper describes the bead pull experimental set up, the software developed for this particular application and the measurements taken.

Poster TUPP047 [1.089 MB]

TUPP049

Test Stand for 325 MHz Power Couplers

multipactoring, vacuum, pick-up, high-voltage

538

S. Kazakov, B.M. Hanna, T.N. Khabiboulline, V. Poloubotko, O.V. Pronitchev, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

325 MHz superconducting Single Spoke resonators (SSR1) will be utilized in the Project X Injector Experiment (PXIE). Developed in Fermilab the main power coupler will be supply 2kW CW RF power to each cavity. Fermilab developed and designed the special test stand where the couplers will be tested up to 10 kW and design properties be confirmed. This paper describes the design of the coupler test stand and preliminary results of the tests.

TUPP052

SSR1 Tuner Mechanism: Passive and Active Device

cryomodule, alignment, SRF, operation

541

D. Passarelli
Fermilab, Batavia, Illinois, USA

In this paper we present the methodology adopted in designing the mechanism responsible for controlling the resonant frequency of Single Spoke Resonators of first type (SSR1). Such device is capable of compensating the effects of external perturbations, such as pressure fluctuations and microphonics, on the frequency of SSR1. The compensation is achieved through active responses via an actuation system and passive responses which are inherent to the elastic behavior of the overall system. The first experiences in the design, assembly, QA and testing are reported.

Poster TUPP052 [2.368 MB]

TUPP055

Progress on Euclid SRF Conical Half-Wave Resonator Project

niobium, vacuum, SRF, proton

547

E.N. Zaplatin
FZJ, Jülich, Germany
T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
Euclid conical Half-Wave Resonator (cHWR) project develops 162.5 MHz β=v/c=0.11 accelerator structure for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main idea of this project is to provide a self-compensation cavity design together with its helium vessel to minimize the resonant frequency dependence on external loads. A unique cavity side-tuning option is also under development. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests to demonstrate such possibility for the private company. Here we present the procedure of the cavity and helium vessel fabrication, cavity preparation and initial experimental results.

TUPP060

Development of a 217 MHz Superconducting CH Structure

simulation, linac, operation, accelerating-gradient

563

M. Basten, M. Amberg, M. Busch, F.D. Dziuba, D. Mäder, H. Podlech
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher, W.A. Barth, S. Mickat
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: Helmholtz-Institut Mainz, Bundesministerium für Bildung und Forschung contract number 05P12RFRBL
To compete in the production of Super Heavy Elements (SHE) in the future a 7.3 AMeV superconducting (sc) continuous wave (cw) LINAC is planned at GSI. The baseline design consists of 9 sc Crossbar-H-mode (CH) cavities operated at 217 MHz. Currently an advanced cw demonstrator is under design at the Institute for Applied Physics (IAP) at Frankfurt University. The purpose of the advanced demonstrator is to investigate a new concept for the superconducting CH structures. It is based on shorter CH-cavities with 8 equidistant gaps without girders and with stiffening brackets at the front and end cap to reduce the pressure sensitivity. One major goal of the advanced demonstrator is to show that the new design leads to higher acceleration gradients and smaller E_p/E_a values. In this contribution first simulation results and technical layouts will be presented.

Poster TUPP060 [0.593 MB]

TUPP062

A Rebunching CH Cavity for Intense Proton Beams

linac, quadrupole, multipole, simulation

566

M. Schwarz, C. Claessens, M. Heilmann, O. Hinrichs, D. Koser, O. Meusel, D. Mäder, H. Podlech, U. Ratzinger, A. Seibel
IAP, Frankfurt am Main, Germany

Funding: Project supported by the EU, FP7 MAX, Contract No. 269565
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is currently under construction at the Goethe-University in Frankfurt am Main (Germany). A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final proton energy as well as for focusing the bunch longitudinally to compensate huge space charge forces at currents up to 200 mA at the final stage of extension. High current beam dynamic simulations have been performed. They include benchmarking of different beam dynamic codes like LORASR and TraceWin, as well as validating the results by measurements. Detailed examination of multipole field impact, due to the cavity’s geometry, together with error tolerance studies and thermal simulations are also performed. Furthermore, this CH rebuncher serves as a prototype for rt CH cavities at MYRRHA (Belgium), an Accelerator Driven System for transmutation of high level nuclear waste. After copper plating the cavity, RF conditioning will start soon.

Poster TUPP062 [6.015 MB]

TUPP064

Zero-Current Longitudinal Beam Dynamics

lattice, resonance, damping, linac

572

J.-M. Lagniel
GANIL, Caen, France

In linacs, the longitudinal focalization is done by nonlinear forces and the acceleration induces a damping of the phase oscillations. The longitudinal beam dynamics is therefore complex, even when the nonlinear space-charge forces are ignored. The three different ways to study and understand this zero-current longitudinal beam dynamics will be presented and compared.

TUPP065

RF Input Power Couplers for High Current SRF Applications

booster, SRF, linac, simulation

575

V.F. Khan, W. Anders, A. Burrill, J. Knobloch, O. Kugeler, A. Neumann
HZB, Berlin, Germany
H. Wang
JLab, Newport News, Virginia, USA

High current SRF technology is being explored in present day accelerator science. The BERLinPro project is presently being built at the HZB to address the challenges involved in high current SRF machines. A 100 mA electron beam is designed to be accelerated to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling high input RF power for the gun as well as booster cavities where there is no energy recovery process. A high power co-axial input coupler is being developed to be used for the booster and gun cavities at the nominal beam current. The coupler is based on the KEK–cERL coupler design. The KEK coupler design has been modified to minimise the penetration of the tip in the beampipe without compromising on beam-power coupling ( Qext ~1 x 105). Herein we report on the RF design for the high power (130 kW) BERLinPro (BP) couplers along with the test stand for conditioning the couplers. We will also report on the RF conditioning of the TTF-III couplers modified for cw operation (low power ~ 10 kW) which will be utilised in a new 4-mA SRF Photoinjector and the BERLinPro main linac cryomodule.

Slides TUPP065 [2.465 MB]

TUPP066

Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE

gun, SRF, electron, solenoid

578

A. Arnold, M. Freitag, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
HZDR, Dresden, Germany
G. Ciovati, P. Kneisel, L. Turlington
JLab, Newport News, Virginia, USA

As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (Epk=50 MV/m @ Q0=10¹⁰) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly behind the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.

Poster TUPP066 [1.220 MB]

TUPP067

Chopper Operation for the Tandem Scrapers at the J-PARC Linac

linac, operation, software, timing

581

K. Futatsukawa, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono
KEK, Ibaraki, Japan
E. Chishiro, K. Hirano, F. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan

In the J-PARC linac, the energy upgrade from 181 MeV to 400 MeV by the installation of annular-ring coupled structure (ACS) cavities was successfully achieved in 2013. In the next stage, we will schedule the intensity upgrade by the increase of the beam current by improving the front-end in this summer. Then, the high heat load of the scraper, which stops the kicked-beam by the RF chopper, is predicted to damage the surface. Therefore, we prepare the tandem scrapers to suppress the heat load. The half of the kicked beam leads to a scraper and the residual is to the other. Its chopping expedient will be achieved by reversing the phase of the RF chopper on the periodic cycle at the low-level RF system. In this paper, I would like to introduce this system and present the result of the low-level test.

TUPP068

New SRF Facility at KEK for Mass-Production Study in Collaboration with Industries

cryomodule, SRF, operation, cryogenics

584

H. Hayano
KEK, Ibaraki, Japan

The construction of the new SRF facility next to the KEK-STF facility has started from 2014 for the mass-production study of SRF accelerators in collaboration with industries. The new building for this facility has the dimension of 80 m x 30 m, and the plan is to install clean-room for cavity-string assembly, cryomodule-assembly facility, cryogenic system, vertical test facility, cryomodule test facility, input coupler process facility, cavity Electro-Polishing (EP) facility, and control-room/office-rooms in it. The purpose of this new SRF facility is to establish a close collaboration between SRF researchers and industries in order to prepare for the upcoming large-scale future SRF project, like ILC. This paper describes the infra-structure detail and the plan to utilize for future SRF accelerators.

TUPP071

Vortex-Penetration Field at a Groove with a Depth Smaller than the Penetration Depth

experiment, framework, vacuum

590

T. Kubo
KEK, Ibaraki, Japan

Analytical models of the magnetic field enhancement at pits were presented at SRF2013 last year. In this presentation, I will show updated models.
proceedings of SRF 2013, Paris, France (2013), p. 430

TUPP072

Studies on Wake Field in Annular Coupled Structure

wakefield, impedance, linac, acceleration

593

Y. Liu, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
K. Futatsukawa
KEK, Ibaraki, Japan
A. Miura
JAEA/J-PARC, Tokai-mura, Japan

LINAC injector of J-PARC (Japan Proton Accelerator Research Complex) was recently successfully upgraded from 181 MeV to 400 MeV, applying a type of coupled cavity linac (CCL) structure ACS (Annular Coupled Structure). It was warmly discussed since very beginning on the wake field in the ACS cavities, where there are CCL modes with the same number as that of cells within ~50 MHz, possibly resonating with high intensity proton/H⁻ beams. One of the most important effects from the wake field is the influence on the ACS phase scan. Analytical and simulation studies, as well as the countermeasures were prepared before the energy upgrade. Fortunately we found that detuning of the ACS was unnecessary, which helped to save much work in the commissioning. In addition we got chance to make experiment studies. It was also discussed why the wake field is not so serious as we expected at the very beginning.

TUPP073

Study of the ACS Cavity Without a Bridge Cavity

linac, coupling, proton, alignment

596

F. Naito, K. Takata
KEK, Ibaraki, Japan
H. Ao, K. Hasegawa, K. Hirano, T. Morishita, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan

J-PARC has installed the Annular-ring Coupled Structure (ACS) linac to increase the beam energy up to 400 MeV. One ACS module is composed of two accelerating tanks which are coupled by the bridge cavity. The bridge cavity simplifies the handling of the multi-tank system. While it is possible to feed the RF power into the each tanks directly with the power divider and the phase shifter instead of the bridge cavity. The rf properties of the ACS linac with the direct rf-power supply system has been measured by using the low power model made of aluminum. The measured results are described in the paper.

Slides TUPP073 [5.042 MB]

TUPP078

High Gain FEL with a Micro-bunch Structured Beam by the Transverse-Longitudinal Phase Space Rotation

FEL, radiation, electron, cathode

607

M. Kuriki, Y. Seimiya
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, K. Ohmi
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
R. Kato
ISIR, Osaka, Japan

FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. That results the longitudinal micro-bunch structure. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. A compact FEL facility based on this method is proposed.

Poster TUPP078 [0.594 MB]

TUPP080

Commissioning of the MAX 700 MHz Test Stand

cryomodule, controls, operation, experiment

610

J.-L. Biarrotte, F. Chatelet, M. El Yakoubi, N. Gandolfo, C. Joly, J. Lesrel, H. Saugnac
IPN, Orsay, France
A. Bosotti, R. Paparella, P. Pierini
INFN/LASA, Segrate (MI), Italy
F. Bouly
LPSC, Grenoble Cedex, France
I. Martin-Hoyo
ADEX, Madrid, Spain

The MYRRHA project aims at the construction of an Accelerator Driven System demonstrator. The criticality will be sustained by an external spallation neutron flux produced thanks to a 600 MeV high intensity proton beam. This beam will be delivered by a superconducting linac which must fulfil very stringent reliability requirements. Under the MAX (MYRRHA Accelerator eXperiment) program, which aims at pursuing the R&D activities on the ADS-type accelerator, a 700 MHz Cryomodule was developed. The main goal of this test stand is to dispose of a facility to carry out “real scale” reliability oriented studies on a RF Superconducting cavity of the high-energy linac section. This module holds 5-cells elliptical cavity equipped with its blade cold tuning system and its coaxial power coupler. The experimental work undertaken at IPN Orsay, has allowed to fully qualify the module in machine configuration (high RF power, at 2K), including assessment of the tuning system and measurement of microphonics spectrums. During this study the dynamic behavior of the fast tuning system of the cavity was also measured. We review here the obtained results and lessons learnt by operating this module.

TUPP082

The MYRRHA Spoke Cryomodule Design

cryomodule, linac, framework, cryogenics

613

H. Saugnac, J.-L. Biarrotte, S. Blivet, P. Duchesne, N. Gandolfo, J. Lesrel, G. Olry, E. Rampnoux, D. Reynet
IPN, Orsay, France

In the framework of the MAX project, dedicated to the detailed study of the MYRRHA facility LINAC, the engineering study of the ‘Spoke’ cavities cryomodule, situated in the low energy superconducting section, has been achieved. The beam optics, highly constrained by strong reliability requirements, leads to a modular cryomodule composed of two β=0.37, 352 MHz, single bar ‘Spoke’ cavity cooled at 2K. The power coupler design, not studied in detail under the MAX project, is directly taken from a 20 kW continuous wave 352 MHz coupler designed and successfully tested in the framework of the previous EUROTRANS and EURISOL projects. The cold tuning system is identical to the one designed for the ESS ‘Spoke’ cavities. We present in this paper, the RF, the mechanical and the thermal design of the complete cryomodule as well as the optimization and simulations of its individual components (Cavity, Cryostat, Tuning System…).

TUPP083

Design and Analysis of Slow Tuner in the Superconducting Cavity of RISP

superconducting-cavity, niobium, target, SRF

616

M.O. Hyun, H.C. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the Rare Isotope Science Project of Institute of Basic Science funded by the Ministry of Science, ICT and Future Planning and National Research Foundation.
Superconducting cavity is one of the most complex systems from the view of mechanical engineering, which is installed and operated in the superconducting linear accelerator. In order to operate SC cavity properly and precisely, superconducting cavity needs many sub-systems, including power coupler for applying RF power inside cavity, and liquid helium jacket for cooling cavity until reaching to the superconducting conditions. And, also cavity needs frequency tuning system for adjusting operating frequency when RF frequency of cavity is changed with outer disturbances such as liquid helium fluctuation, mechanical deformation due to vacuum condition of cavity. Generally, this tuning system is called as a tuner. There are two types of tuner, one is slow tuner which operates with motor, and the other is fast tuner which operates with piezo-electric actuator. This paper describes about design process and analysis results about slow tuner.

TUPP084

Surface Treatment Facilities for SCRF Cavities at RISP

vacuum, superconducting-cavity, niobium, superconducting-RF

619

J. Joo, D. Jeon, M.J. Joung, Y. Jung, H.J. Kim, M. Lee
IBS, Daejeon, Republic of Korea

Rare Isotope Science Project is engaged in the fabrication of four types of superconducting RF cavities. The surface treatment is one of the important processes of superconducting RF cavity fabrication. New superconducting RF cavity processing systems have been designed and developed for the etching of niobium in buffered chemical polish at RISP. The safety precautions used in protecting the operator from the acids used in the etchant and from the fumes given of during the process are discussed. All of the new hardware will be located in RISP Munji Superconducting Cavity Test Facility.

TUPP085

RAON Cryomodule Design for QWR, HWR, SSR1 and SSR2

cryomodule, simulation, linac, vacuum

622

W.K. Kim, H. Kim, H.J. Kim, Y. Kim, M. Lee, G.-T. Park
IBS, Daejeon, Republic of Korea

The accelerator called RAON which will be built in Korea has four kinds of superconducting cavities such as QWR, HWR, SSR1 and SSR2, operating at 2 K and 4.5 K [1]. The current status of design for the QWR, HWR, SSR1 and SSR2 cryomodules are reported. The issues included in the paper are thermal and structural design results of the components such as supports and thermal shield in the cryomodules. The cryomodule hosts the superconducting cavities in high vacuum and thermally insulated environment in order to maintain the operating temperature of superconducting cavities. It also keeps the cavities in a good alignment to the beam line. It has an interface for supplying RF power to cavities between cold and warm components. The whole configuration of the integrated system is also presented. This paper presents the detailed design of the cryomodule.

TUPP086

RAON Superconducting Radio Frequency Test Facility Construction

radiation, cryogenics, SRF, electron

625

H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin
IBS, Daejeon, Republic of Korea

Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP088

The Fabrication of the β=0.12 HWR at RISP

niobium, target, vacuum, electron

628

G.-T. Park, H.J. Cha, Y. Jung, H. Kim, W.K. Kim
IBS, Daejeon, Republic of Korea

At RISP, the superconducting cavities have been developed to construct RAON, the heavy ion accelerator. Among the cavities, the fabrication of the QWR (Quarter wave resonator) and the HWR (Half wave resonator)are complete. The detailed fabrication processes including material inspection, forming, the electron beam welding, and the clamp up test are described.

TUPP089

Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac

DTL, linac, simulation, resonance

631

M.R. Khalvati
IPM, Tehran, Iran
S. Ramberger
CERN, Geneva, Switzerland

The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H–beams of up to 40 mA average pulse current from 3 to 50 MeV. The structure consists of three cavities. The first cavity (Tank1) is a 3.9 m long tank containing 38 drift tubes, 10 fixed tuners, 2 movable tuners and 12 post-couplers, operating at a frequency of 352.2 MHz and an average accelerating field of 3.1 MV/m. This paper reports on the results and procedures used for the low–power tuning, stabilization and power coupler tuning carried out on the first Linac4 DTL tank. The upgrade of the bead pull measurement system and twists to the well-known tilt sensitivity technique are discussed.

TUPP093

The Couplers for the IFMIF-EVEDA RFQ High Power Test Stand at LNL: Design, Construction and Operation

coupling, vacuum, rfq, simulation

643

E. Fagotti, L. Antoniazzi, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, C. R. Roncolato
INFN/LNL, Legnaro (PD), Italy

In order to assess the critical aspects of the IFMIF-EVEDA RFQ construction procedure and operation, it was decided to perform a High Power Test of a subset of the RFQ consisting in its last 550 mm three modules (out of 18) plus a Prototype Module, 390 mm long, used as RF plug. These modules are going to be tested at full power in CW of INFN LNL Labs, in the so-called RFQ High Power Test Stand. For such a purpose, a RF tube-based amplifier capable of 220 kW CW output power at the operational frequency of 175 MHz was purchased from an Italian company. A critical component of this test is the RF power coupler. Therefore INFN-LNL developed a design of two identical water-cooled loop antenna couplers, built with OFE copper and vacuum sealed with a commercially available 6”1/8 Alumina planar window. These couplers were tested separately on an aluminium coupling cavity. In particular one of them acts as a power feeder, while the other one, connected with a 200 kW water-cooled load, acts as a receiver. In this paper, the main aspects of the design, construction and tests performed on the couplers and coupling cavity will be described.

TUPP094

Recent Progress of Beam Commissioning at J-PARC Linac

linac, operation, acceleration, DTL

646

T. Maruta
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan
M. Ikegami
FRIB, East Lansing, Michigan, USA
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
A. Miura, H. Sako
JAEA/J-PARC, Tokai-mura, Japan

We installed Annular-type Coupled Structure (ACS) linac in year 2013 in present linac downstream to extend the beam energy from 181 to 400 MeV. The beam commissioning had been conducted for one month in last December to January, and then we successfully extract 400 MeV beam. Whereas, we stably operate the linac at peak current of 15 mA, which is equivalent to 300 kW at the extraction of 3 GeV RCS, we observe unexpected residual radiations in ACS section. In this presentation, we review the recent progress in beam commissioning and beam loss study.

TUPP095

High-Power Test Results of the RFQ III in J-PARC Linac

rfq, operation, vacuum, ion

649

T. Morishita, K. Hasegawa, K. Hirano, Y. Kondo, H. Oguri, S. Yamazaki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Hori
JAEA, Ibaraki-ken, Japan
F. Naito, T. Sugimura, A. Takagi
KEK, Ibaraki, Japan

The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The beam energy of the linac has been upgraded from 181MeV to 400MeV in 2013. For the beam current upgrade, the new frontend (RF ion source, RFQ, chopping system) installation is scheduled in summer 2014 for 1MW operation at RCS. The RFQ III, which is designed for 50mA beam acceleration from 0.05MeV to 3MeV, has been fabricated and the high-power test has started at April 2013 at the test station in the J-PARC. The test station consists of the ion source, the LEBT, the RFQ, and the diagnostics devices. The nominal RF power and RF duty of the RFQ III are 380kW and 3%(0.6ms and 50Hz), respectively. The high-power conditioning reached to the 120% of the nominal power with 1.5% (0.6ms, 25Hz) RF duty within 24 hours. Then, we performed the beam operation at the test station and measured beam parameters after the RFQ III. The results of the high-power conditioning and the stability of the RFQ operation with beam will be discussed.

TUPP101

Vertical Electro-Polishing of Nb Single-Cell Cavity Using Cathode with Variable-Geometry Wings and Its Results of Vertical Test

cathode, power-supply, target, experiment

662

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
P. Carbonnier, F. Éozénou, C. Servouin
CEA/DSM/IRFU, France
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
K. Ishimi
MGI, Chiba, Japan
C. Madec, L. Maurice
CEA/IRFU, Gif-sur-Yvette, France

Marui Galvanizing Co. Ltd. has been studying Vertical Electro-Polishing (VEP) on Nb superconducting accelerator cavity with the goal of mass-production and cost-reduction of Electro-Polishing (EP) process in collaboration with KEK and CEA Saclay. And we invented variable-geometry wings cathode for VEP process to get uniform distributions of both electric current and EP solution flow. Using this cathode, we performed various tests of VEP with Nb single-cell cavities. In this article, we will report the results of vertical test of Nb single-cell cavity which is VEP’ed by cathode with variable-geometry wings.

TUPP103

The Beam Envelope Control in SC Linac for the Proton Radiotherapy

linac, controls, proton, simulation

665

A.V. Samoshin, I.A. Ashanin, S.M. Polozov
MEPhI, Moscow, Russia

Proton cancer therapy is conventionally based on normal conducting synchrotrons and cyclotrons. The high electrical power consumption and especial devices necessary to energy variation are main problems of such facilities. Superconducting linacs based on short identical independently phased cavities have a seriously progress and it's development allow to propose their using for medical application. High accelerating gradient and small capacity losses nearly 10^-4 Vt/m are main advantages in advance of normal conducting facilities, the energy variation can be realized by means of RF field amplitude and phase variation in a number of cavities. Besides linac structures are lack of unwieldy magnetic system, simplicity of input and output of particles and high current densities. The parameters choose and the optimization for SC linac structure with energy up to 240 MeV and envelope control will discuss in this paper. The simulation was done using BEAMDULAC-SCL code*. The study of beam dynamics will direct to realize the energy variation in range 150-240 MeV with beam quality preservation.
* A.V. Samoshin. Proc. of LINAC2012, Tel-Aviv, Israel, TUPB069, p. 630 - 632

TUPP106

RF Characteristics of 20K Cryogenic 2.6-cell Photocathode RF-gun Test Cavity

gun, simulation, cryogenics, database

671

T. Sakai, M. Inagaki, K. Nakao, K. Nogami, T. Tanaka
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
T.S. Shintomi
Nihon University, Tokyo, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
The cryogenic C-band photocathode RF gun operating at 20K is under development at LEBRA in Nihon University. The RF gun is of the BNL-type 2.6-cell pillbox cavity with the resonant frequency of 5712 MHz. The 6N8 high purity OFC copper is used as the cavity material. From the theoretical evaluation of the anomalous skin effect, the quality factor Q of the cavity has been expected to be about 60000. Considering a low cooling capacity of the cryocooler system, initial operation of the RF gun is assumed at a duty factor of 0.01 %. The cavity basic design and the beam bunching simulation were carried out using SUPERFISH and General Particle Tracer (GPT). Machining of the cavity was carried out in KEK. The RF characteristics measured at room temperature and 20K will be reported.

TUPP108

HOM and Impedance Study of RF Separators for LCLS II

HOM, dipole, superconducting-RF, impedance

674

S.U. De Silva, J.R. Delayen, B.R.P. Gamage, G.A. Krafft, T. Satogata
ODU, Norfolk, Virginia, USA
R.G. Olave
Old Dominion University, Norfolk, Virginia, USA

The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.

Poster TUPP108 [1.032 MB]

TUPP109

Cryogenic Testing of High-Velocity Spoke Cavities

cryogenics, acceleration, proton, linac

677

C.S. Hopper, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA

Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

TUPP112

Study of a C-Band TW Electron Gun for SwissFEL

gun, cathode, emittance, klystron

686

M. Schaer, A. Citterio, P. Craievich, L. Stingelin, R. Zennaro
PSI, Villigen PSI, Switzerland

For a future upgrade of the SwissFEL facility, the replacement of the S-band standing wave electron gun by a C-band standing wave, or traveling wave gun is investigated. The full model of the C-band TW gun is calculated with HFSS and is characterized by an almost vanishing group velocity in the first cell to increase the field at the cathode. ASTRA simulations predict that in the case of the C-band SW gun, a two times higher peak current of ~ 40 A can be generated while still preserving the low slice emittance of ~ 0.2 um at 200 pC, due to the higher electric field on cathode and improved magnetic focusing. This would help to halve the overall beam compression factor, relax the phase stability requirement of S- and X-band systems operated off-crest for compression and decrease the gain curve in theμbunch instability. Compared to the SW gun, a TW gun provides a more homogeneous acceleration and does not require any circulator. In this study, the preliminary RF design and beam performance of a C-band TW gun is presented and compared to a pure C-band SW gun presently under design at Paul Scherrer Institut and to the operating S-band SW gun.

TUPP113

High RF Power Test of Coupled RFQ-SFRFQ Cavity

rfq, simulation, impedance, detector

689

W.L. Xia, J.E. Chen, S.L. Gao, F.J. Jia, Y.R. Lu, Z. Wang, J. Zhao, K. Zhu
PKU, Beijing, People's Republic of China

Funding: This work was supported in part by the National Natural Science Foundation of China under Grant No. 11075008, 11079001 and 11175009.
A new combined accelerator that couples radio frequency quadrupole (RFQ) and separated function radio frequency quadrupole (SFRFQ) in a single cavity has been designed and manufactured. Recently, the performance of the cavity under high RF power was tested with an upgraded RF power source. The inter-vane voltages of both RFQ section and SFRFQ section were measured by using high purity germanium detector and the corresponding measurement system. The measured shunt impedance is about 546.9 kΩ•m, which means the cavity needs 19.5 kW for the designed inter-vane voltage of 65 kV. The results are well consistent with the cavity design.

Poster TUPP113 [0.764 MB]

TUPP117

Commissioning of Vertical Test Stand Facility for 2 K Testing of Superconducting Cavities at RRCAT

radiation, shielding, controls, cryogenics

695

S.C. Joshi, A. Chauhan, P. Fatnani, P.D. Gupta, M.K. Kumar, P.K. Kush, P. Mohania, S. Raghvendra, P. Shrivastava, S.K. Suhane
RRCAT, Indore (M.P.), India

Raja Ramanna Centre for Advanced Technology (RRCAT) has developed a 2K vertical Test Stand (VTS) facility for characterization of Superconducting RF (SCRF) cavities, under Indian Institution Fermilab Collaboration (IIFC). The VTS facility comprises of a large size liquid helium (LHe) cryostat, cryogenic system, RF power supply, control and data acquisition system and radiation monitoring system. It will facilitate testing of superconducting cavities of different frequencies ranging from 325 MHz low beta to 650 MHz / 1.3 GHz medium and high beta cavities. The helium vessel has a capacity to store up to 2900 litres of liquid Helium. The cryostat is installed inside a vertical pit. It is equipped with facilities for supply of liquid nitrogen and liquid helium and vacuum system for pumping out helium gas to lower the temperature of liquid helium bath down to 1.8 K. A 200 W, 1.3 GHz RF system has been indigenously developed for testing of the SCRF cavities. The VTS facility has now been commissioned and its performance validation has been successfully carried out by benchmarking it with respect to the facility at the Fermilab.

TUPP119

Design Studies for Medium and High beta SCRF Cavities for Indian Spallation Neutron Source

linac, HOM, lattice, quadrupole

699

A.R. Jana, V. Kumar
RRCAT, Indore, India

There is a plan to build a 1 GeV H⁻ linac for the proposed Indian Spallation Neutron Source (ISNS) at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore. The medium and high energy section of the ISNS linac will consist of beta_g=0.61, as well as beta_g = 0.9, 650 MHz, 5-cell superconducting radiofrequency (SCRF) cavities, for which detailed electromagnetic design studies have been performed. During our design study, we have evolved a generalized procedure for the optimization of geometrical parameters of multi-cell SCRF cavities. Studies on higher order modes supported by the cavity and its effect on beam dynamics, as well as on heat load to the cavity have been performed, which constitute an important aspect of the design study. Finally, detailed studies on Lorentz Force Detuning (LFD) have been performed, and design of the cavity has been optimized to minimize the effect due to the LFD. The paper discussed the details of the calculations and the studies that have been performed during the design study.

TUPP123

Design of Novel RF Sources to Reduce the Beam Pace-Charge Effects

electron, klystron, space-charge, cathode

712

M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: DOE
Traditional RF sources, such as Klystrons, TWT require a magnet (such as a solenoid) in order to maintain the electron beam focusing, compensating the particle repulsion caused by space charge effects. We designed a novel RF source with an alternative approach that reduces beam space charge problems. This paper shows the design of the device, with a new formulation of the Child’s Law, and the mode-beam stability analysis. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics.

Poster TUPP123 [0.172 MB]

TUPP133

Optimization of the RF Cavity of the Medical Purpose Electron Linac by Using Genetic Algorithm

electron, impedance, linac, acceleration

726

S. Shin, J.-S. Chai
SKKU, Suwon, Republic of Korea

A compact electron linear accelerator for the medical application has been developing at Sungkyunkwan University. Due to this electron linac is attached on the robot arm or gantry, it should be compact enough to be held by the structure. An X-band technology has been used to meet the requirements for the compact linac. Because the particle accelerator is complex and sensitive machine to design it takes a lot of time to get a good performance accelerator. In this research, a special technique named single-objective genetic algorithm for the optimization process has been applied to achieve a better RF cavity design by changing various geometric parameters.

TUPP138

Analysis of New High-Q0 SRF Cavity Tests by Nitrogen Gas Doping at Jefferson Lab

injection, SRF, niobium, vacuum

736

A.D. Palczewski, R.L. Geng, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In order to refine systematic understanding and establish confident process control, Jefferson Lab has joined with partners to investigate and thoroughly characterize the dramatically higher Q0 of 1.3 GHz niobium cavities first reported by FNAL in 2013[1]. With partial support from the LCLS-II project, JLab has undertaken a parametric study of nitrogen doping in vacuum furnace at 800 C followed by variable depth surface removal in the 5 - 20 μm range. Q0 above 3×10¹⁰ are typical at 2.0 K and 16 MV/m accelerating field. We report observations from the single cell study and current interpretations. In addition to the parametric single cell study, we also report on the ongoing serial testing of six nitrogen-doped 9-cell cavities as baseline prototypes for LCLS-II.
[1] A. Grassellino, et al., Supercon. Sci.and Tech., 2013. 26(10): p. 102001

Poster TUPP138 [4.214 MB]

TUPP139

Design Studies with DEMIRCI for SPP RFQ

rfq, software, interface, ion

740

B. Yasatekin, G. Turemen
Ankara University, Faculty of Sciences, Ankara, Turkey
A. Alacakir
TAEK, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA

To design a Radio Frequency Quadrupole (RFQ) is a onerous job which requires a good understanding of all the main parameters and the relevant calculations. Up to the present there are only a few software packages performing this task in a reliable way. These legacy software, though proven in time, could benefit from the modern software development tools like Object Oriented (OO) programming. In this note, a new RFQ design software, DEMIRCI is introduced. It is written entirely from scratch using C++ and based on CERN's OO ROOT library. It has a user friendly graphical user interface and also a command line interface for batch calculations. It can also interact by file exchange with similar software in the field. After presenting the generic properties of DEMIRCI, its compatibility with similar software packages is discussed based on the results from the reference design parameters of SPP (SNRTC Project Prometheus), a demonstration accelerator at Ankara, Turkey.

Poster TUPP139 [11.590 MB]

WEIOA01

Construction and RF Conditioning of the Cell-Coupled Drift Tube Linac (CCDTL) for Linac4 at CERN

linac, vacuum, coupling, quadrupole

746

A.G. Tribendis, Y.A. Biryuchevsky, E. Kendjebulatov, Ya.G. Kruchkov, E. Rotov, A.A. Zhukov
BINP SB RAS, Novosibirsk, Russia
Y. Cuvet, A. Dallocchio, J.-F. Fuchs, F. Gerigk, J.-M. Giguet, J. Hansen, T. Muranaka, E. Page, B. Riffaud, N. Thaus, M. Tortrat, M. Vretenar, R. Wegner
CERN, Geneva, Switzerland
M.Y. Naumenko
RFNC-VNIITF, Snezhinsk, Chelyabinsk region, Russia

This paper reports on the construction experience of the Linac4 CCDTL, which took place in two Russian institutes in the framework of three ISTC projects in close collaboration with CERN. The tanks were constructed at VNIITF, Snezhinsk, while the drift tubes and supports were made at BINP, Novosibirsk. All structures were then assembled and tuned at BINP before shipment to CERN where the high-power conditioning took place. The tuning principles, quality checks and conditioning results are presented.

Slides WEIOA01 [4.909 MB]

WEIOA04

Phase Locked Magnetrons for Accelerators

injection, cathode, controls, electron

751

A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Magnetrons offer lower capital costs and higher efficiencies than klystrons, however are natural oscillators rather than amplifiers. This paper reviews techniques and issues for applying high efficiency L band magnetrons to long pulse, high intensity proton linacs. Reference is made to a proof of principle experiment whereby the phase of an SRF cavity was accurately controlled when energised by a magnetron.

Slides WEIOA04 [1.224 MB]

WEIOA06

Low Level RF for SRF Accelerators

LLRF, controls, SRF, operation

760

J. Branlard
DESY, Hamburg, Germany

Low level radio frequency (LLRF) systems are a fundamental component of superconducting RF accelerators. Since the release of the MicroTCA standard (MTCA.4), major developments in MTCA.4-based LLRF systems have taken place. State-of-the-art LLRF designs deliver better than 10^-4 relative amplitude and 10 mdeg phase stability for the vector sum control of SRF cavities. These developments in LLRF systems architecture and technology, driven by research institutes and supported by the industry are of highest importance for the European XFEL, but also for other SRF-based projects such as LCLS-II and the ESS, as well as for the next generation accelerators with 10-5 and mdeg regulation requirements.

Slides WEIOA06 [5.812 MB]

WEIOB03

Status of RAON Heavy Ion Accelerator Project

ion, rfq, linac, target

775

D. Jeon, H.J. Kim
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning (MSIP) and the NRF of Korea under Contract 2013M7A1A1075764.
Construction of the RAON heavy ion accelerator facility is under way in Korea to build the In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) facilities to support cutting-edge researches in various science fields. At present prototyping of major components are proceeding including 28 GHz ECR ion source, RFQ, superconducting cavities, magnets and cryomodules. Superconducting magnets of 28 GHz ECR ion source are fabricated and tested. First article of prototype superconducting cavities are delivered that were fabricated through domestic vendors. Prototype HTS quadrupole is under development. Progress report of the RAON accelerator systems is presented.

Slides WEIOB03 [6.228 MB]

WEIOB04

CW Heavy Ion Accelerator With Adjustable Energy for Material Science

ion, linac, rfq, heavy-ion

780

S.V. Kutsaev, B. Mustapha, J.A. Nolen, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357
The proposed eXtreme MATerial (XMAT) research facility at ANL’s Advanced Photon Source (APS) combines medium-energy heavy-ion accelerator capability with the high-energy X-ray analysis to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. The XMAT facility requires CW heavy ion accelerator with adjustable beam energy in the range of 300 keV/u to 1.25 MeV/u. Such an accelerator has been developed and based on ECR, normal conducting RFQ and multi-gap quarter wave resonators (QWR) operating at 60 MHz. This talk will present complete 3D beam dynamics studies and multi-physics design of both RFQ and QWRs. The design includes a beam transport system capable to focus ions into 20-micron diameter spot on the target.

Slides WEIOB04 [1.159 MB]

THIOA01

Cost Optimized Design of High Power Linacs

linac, neutron, emittance, acceleration

785

M. Eshraqi
ESS, Lund, Sweden

The research accelerators are growing in energy and power which translates to an increase in their cost, and also size if the conventional acceleration techniques are used. On the other hand, handling megawatts of power requires a design that is robust, respects the known criteria in beam physics to avoid losses in the order of less than one part in million. Traditionally cost increases with power and quality of the accelerator and beam. In this paper, using the ESS linac as an example, this tradition is challenged and ways to reduce the cost while neither quality nor power is compromised are presented.

Slides THIOA01 [8.363 MB]

THIOA02

Superconducting RF Development for FRIB at MSU

cryomodule, solenoid, operation, SRF

790

K. Saito, N.K. Bultman, E.E. Burkhardt, F. Casagrande, S.K. Chandrasekaran, S. Chouhan, C. Compton, J.L. Crisp, K. Elliott, A. Facco, A.D. Fox, P.E. Gibson, M.J. Johnson, G. Kiupel, R.E. Laxdal, M. Leitner, S.M. Lidia, I.M. Malloch, D. Miller, S.J. Miller, D. Morris, D. Norton, R. Oweiss, J.P. Ozelis, J. Popielarski, L. Popielarski, A.P. Rauch, R.J. Rose, T. Russo, S. Shanab, M. Shuptar, S. Stark, N.R. Usher, G.J. Velianoff, D.R. Victory, J. Wei, G. Wu, X. Wu, T. Xu, T. Xu, Y. Yamazaki, Q. Zhao, Z. Zheng
FRIB, East Lansing, Michigan, USA

Funding: *This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
FRIB is a $730M heavy ion accelerator project and a very large scale machine for many nuclear physics users. The civil construction started on March 17th 2014. The SRF system design and development have completed. The machine is to be in early completion end of 2019. FRIB accelerates ion species up to 238U with energies of no less than 200MeV/u and provides a beam power up to 400kW. Four SRF cavity families are used from β=0.041, 0.085 (QWRs) to 0.29 and 0.53 (HWRs). 8T superconducting solenoids are installed in the cryomodules for space effective strong beam focusing. The biggest challenges are in accelerating the high-power heavy ion beams from the very low energy to medium energy and the stable operation for large user community. The SRF cryomodule design addressed three critical issues: high performance, stable operation and easy maintainability, which chose several unique technical strategies, e.g.2K operation, bottom up cryomodule assembly, local magnetic shielding and so on. This talk will include high performance cavity R&D, local magnetic shielding, flux trapping by solenoid fringe field, and bottom up cryomodule assembly.

Slides THIOA02 [5.049 MB]

THIOA03

Status of the HIE-ISOLDE Linac

cryomodule, linac, solenoid, vacuum

795

W. Venturini Delsolaro, L. Alberty, L. Arnaudon, K. Artoos, J. Bauche, A.P. Bernardes, J.A. Bousquet, E. Bravin, S. Calatroni, E.D. Cantero, O. Capatina, N. Delruelle, D. Duarte Ramos, M. Elias, F. Formenti, M.A. Fraser, J. Gayde, S. Giron, N.M. Jecklin, Y. Kadi, G. Kautzmann, Y. Leclercq, P. Maesen, V. Mertens, E. Montesinos, V. Parma, G.J. Rosaz, K.M. Schirm, E. Siesling, D. Smekens, A. Sublet, M. Therasse, D. Valuch, G. Vandoni, E. Vergara Fernandez, D. Voulot, L.R. Williams, P. Zhang
CERN, Geneva, Switzerland

The HIE-ISOLDE project aims at increasing the energy of the radioactive beams (RIB) of REX-ISOLDE from the present 3 MeV/u up to 10 MeV/u for A/q up to 4.5. This will be accomplished by means of a new superconducting linac, based on independently phased quarter wave resonators using the Nb sputtering on copper technology, and working at 101.28 MHz. The focusing elements are superconducting solenoids providing 13.5 T2m field integral. These active elements are contained in a common vacuum cryostat. The presentation will cover the status of advancement of the HIE-ISOLDE linac technical systems. The performance of the superconducting elements will be presented, together with the assembly work of the cryomodule in clean room and the planned qualification tests in the horizontal test facility at CERN

Slides THIOA03 [24.692 MB]

THIOA04

Superconducting Cavities and Cryomodules for Proton and Deuteron Linacs

cryomodule, linac, vacuum, cryogenics

801

G. Devanz
CEA/IRFU, Gif-sur-Yvette, France

We review the recent advances in the design plans and test results of the superconducting structures for proton (ESS) and deuteron linacs (SPIRAL2, IFMIF). A variety of RF resonators are used for this purposes, from multicell elliptical cavities for the acceleration of pulsed proton beams to half and quarter wave resonators for CW deuteron beams. The increase in beam power with respect to previous generations of linacs brings new challenges to cavities and RF couplers. Test results of the available SRF prototypes and cryomodules of the aforementioned projects will be presented.

Slides THIOA04 [6.785 MB]

THIOA05

An 800 MeV Superconducting Linac to Support Megawatt Proton Operations at Fermilab

linac, cryomodule, booster, operation

807

V.A. Lebedev, P. Derwent, S.D. Holmes
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Active discussion on the high energy physics priorities in the US carried out since summer of 2013 resulted in changes in Fermilab plans for future development of the existing accelerator complex. In particular, the scope of Project X was reduced to the support of the Long Base Neutrino Facility (LBNF) at the project first stage. The name of the facility was changed to the PIP-II (Proton Improvement Plan). This new facility is a logical extension of the existing Proton Improvement Plan aimed at doubling average power of the Fermilab’s Booster and Main Injector (MI). Its design and required R&D are closely related to the Project X. The paper discusses the goals of this new facility and changes to the Project X linac introduced to support the goals.

Slides THIOA05 [1.597 MB]

THIOB02

SPIRAL2 Cryomodule Production Result and Analysis

cryomodule, operation, linac, cryogenics

814

P.-E. Bernaudin, R. Ferdinand
GANIL, Caen, France
P. Bosland, C. Marchand
CEA/IRFU, Gif-sur-Yvette, France
Y. Gómez Martínez
LPSC, Grenoble Cedex, France
D. Longuevergne, G. Olry
IPN, Orsay, France

The production and qualification of the SPIRAL2 cryomodules are close to the end. Their performances are now well established. This paper will explain the path followed to the good achievements, and show some statistical analyses to be used for future projects. How far can we push the performances? What cryogenics consumption shall we take as design values?

Slides THIOB02 [2.864 MB]

THIOC01

SPIRAL2 Bunch Extension Monitor

cryomodule, detector, linac, background

824

R.V. Revenko, J.L. Vignet
GANIL, Caen, France

Funding: The work is funded in frame of CRISP WP3T1
Superconducting linacs require beam diagnostics to quantify the time extension of the bunch for a proper beam adaptation. Bunch extension monitor (BEM) should provide measurements with required resolution and minimal disturbance of beam properties, have a broad dynamic range of beam intensity and should be easy to use for accelerator routine operation. The design of BEM should take into account operation at the vicinity of cryomodules and satisfy imposed requirements for this. BEM measures the x-rays resulting of the bunch interaction with a tungsten wire. Developed prototype of detector was successfully tested with ions beams. Test for detector background conditions at vicinity of cryomodule was carried out and results are presented.

Slides THIOC01 [7.054 MB]

THIOC03

Operational Experience With CW High Gradient and High QL Cryomodules

cryomodule, controls, EPICS, klystron

834

C. Hovater, T.L. Allison, R. Bachimanchi, E. Daly, M.A. Drury, G.E. Lahti, C.I. Mounts, R.M. Nelson, T. E. Plawski
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of ten new 100 MV cryomodules (80 cavities). The superconducting RF cavities are designed to operate CW at an accelerating gradient of 19.3 MV/m with a QL of 3×107. The RF system employs single cavity control using new digital LLRF controls and 13 kW klystrons. Recently, all of the new cryomodules and associated RF hardware and software have been commissioned and operated in the CEBAF accelerator. Electrons at linac currents up to 10 μA have been successfully accelerated and used for nuclear physics experiments. This paper reports on the commissioning and operation of the cryomodules and RF system.

Slides THIOC03 [5.793 MB]

THPP012

A Prototype 1 Mev X-Band Linac for Aviation Cargo Inspection

linac, electron, simulation, accelerating-gradient

853

M. Jenkins, P.K. Ambattu, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S. Andrews, T.A. Cross, C.R. Weatherup
e2v, Chelmsford, Essex, United Kingdom
P.A. Corlett, P. Goudket, A.R. Goulden, P.A. McIntosh, K.J. Middleman, Y.M. Saveliev, R.J. Smith, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.A. Griffiths, M.D. Hancock, T. Hartnett, C. Hill, J.P. Hindley, B.G. Martlew, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Aviation cargo Unit Load Device (ULD) containers are typically much smaller than standard shipping containers, with a volume of around 1m3. Standard 3-6 MeV X-ray screening linacs have too much energy to obtain sufficient contrast when inspecting ULD’s, hence a lower 1 MeV linac is required. In order to obtain a small physical footprint, which can be adapted to mobile platform applications a compact design is required, hence X-band technology is the ideal solution. A prototype 1 MeV linac cavity has been designed by Lancaster University, manufactured by Comeb (Italy) and tested at STFC Daresbury Laboratory using an e2v magnetron, modulator and electron gun. The cavity is a bi-periodic π/2 structure, with beam-pipe aperture coupling to simplify the manufacture at the expense of shunt impedance. The design, manufacture and testing of this linac structure is presented.

THPP013

Prototype Development of the CLIC Crab Cavities

dipole, damping, simulation, impedance

856

G. Burt, P.K. Ambattu, A.C. Dexter, M. Jenkins, C. Lingwood, B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
V.A. Dolgashev
SLAC, Menlo Park, California, USA
P. Goudket, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Grudiev, G. Riddone, A. Solodko, I. Syratchev, R. Wegner, W. Wuensch
CERN, Geneva, Switzerland
C. Hill, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

CLIC will require two crab cavities to align the beams to provide an effective head-on collision with a 20 mdeg crossing angle at the interaction point. An X-band system has been chosen for the crab cavities. Three prototype cavities have been developed in order to test the high power characteristics of these cavities. One cavity has been made by UK industry and one has been made using the same process as the CLIC main linac in order to gain understanding of breakdown behaviour in X-band deflecting cavities. The final cavity incorporates mode-damping waveguides on each cell which will eventually contain SiC dampers. This paper details the design, manufacture and preparation of these cavities for testing and a report on their status.

THPP016

Nitrogen-Treated Cavity Testing at Cornell

SRF, niobium, linac, vacuum

866

D. Gonnella, F. Furuta, G.M. Ge, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: U.S. Department of Energy
Recent results from Cornell, FNAL, and TJNAF have shown that superconducting RF cavities given a heat treatment in a nitrogen atmosphere show higher Q₀ at operating gradients at 2.0 K than standard SRF cavities. Here we present on recent results at Cornell in which five single cell cavities and three 9-cell cavities were tested after receiving various nitrogen-doping treatments. Cavity performance was correlated with treatment, and samples treated with the cavities were analyzed with SIMS. These results provide new insights into the science behind the excellent performance that is observed in these cavities.

THPP017

Beam-Based HOM Studies of the Cornell Energy Recovery Linac 7-Cell SRF Cavity

HOM, linac, cryomodule, experiment

869

D.L. Hall, A.C. Bartnik, M.G. Billing, R.G. Eichhorn, G.H. Hoffstaetter, M. Liepe, C.E. Mayes, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF Grant DMR-0807731
The 1.3 GHz 7-cell SRF cavity for the Cornell ERL main linac is optimized for high beam current ERL operation with injected CW beam currents of 100 mA. Beam stability at 100 mA requires very strong damping of the Higher-Order-Modes (HOM) in the cavity by HOM beamline absorbers at the ends of the cavity. To verify the optimized design of the cavity and the HOM damping scheme, a prototype 7-cell main linac cavity was installed into the Cornell Horizontal Test Cryomodule (HTC), and inserted into the beamline of the Cornell ERL high current photo-injector. A beam-based method was then used to search for the presence of dangerous HOMs. Individual HOMs were excited using a charge-modulated beam, after which their effect upon an unmodulated beam was observed using a BPM. Data collected was used to calculate loaded Q of observed HOMs. Results show that it is very unlikely that HOMs will cause BBU in the Cornell ERL. In addition, measurements of the temperature rise of the HOM absorber rings during high current CW beam tests were consistent with simulations, indicating that the optimized main linac cavity is capable of operating at the specified current of 100mA in an ERL configuration.

THPP018

Sample Plate Studies Using a High Field TE Cavity With Thermometry Mapping System

niobium, coupling, SRF, experiment

873

D.L. Hall, C.D. Burton, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF Career Grant PHY-0841213
A TE-Mode sample plate cavity capable of sustaining peak fields of >90 mT on the surface of a 10cm diameter sample plate has been developed and tested at Cornell. A thermometry mapping system composed of 40 Allen-Bradley resistors, mounted on the outside of the sample plate, is capable of measuring the surface resistance of the sample with a resolution of 1 nOhm and a spatial resolution of 0.5 cm. In this paper we present the design and expected performance of this high field TE cavity, and show data taken with a sample plate of niobium as well as results from tests qualifying the performance of the thermometry mapping system.

THPP019

Low Kick Coupler for Superconducting Cavities

emittance, dipole, linac, resonance

876

R.G. Eichhorn, C. Egerer, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Results from the high current, low emittance photo injector at Cornell revealed that even with two opposing input couplers, the beam emittance is affected by the coupler kick. As a result, a coupler with low transverse kick is proposed for use in superconducting accelerating cavities. In this coupler, a rectangular waveguide transforms into a coaxial line inside the beam pipe. The geometry of the coupler is tuned to minimize the transverse kick that is important for linear accelerators with low emittance. The coupler can be used in ERL injectors or other linacs for high brightness light sources.

THPP021

Analysis of the RF Test Results from the On-going Accelerator Cavity Production for the European XFEL

superconductivity, SRF, linac, operation

879

D. Reschke, S. Aderhold, V. Gubarev, J. Schaffran, N.J. Walker
DESY, Hamburg, Germany
L. Monaco
INFN/LASA, Segrate (MI), Italy
Y. Yamamoto
KEK, Ibaraki, Japan

Funding: The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 283745 (CRISP)
The main Linac of the European XFEL will consist of 100 superconducting accelerator modules, operated at an average design gradient of 23.6 MV/m. The fabrication by industry (which includes chemical surface preparation) of the required 800 superconducting cavities is now in full swing, with approximately 400 cavities having been delivered to date. In this interim report, we present an analysis of the RF acceptance tests amassed so far.

THPP022

Efficiency of High Order Modes Extraction in the European XFEL Linac

HOM, damping, dipole, linac

883

A.A. Sulimov, J. Iversen, D. Kostin, W.-D. Möller, D. Reschke, J.K. Sekutowicz, J.H. Thie
DESY, Hamburg, Germany
D. Karolczyk, K. Kasprzak, S. Myalski, M. Wiencek, A. Zwozniak
IFJ-PAN, Kraków, Poland

The serial production of components for the European XFEL linac was started in 2011 and reached the planned level of 8 cavities (1 module) per week in 2013. The measurements of High Order Modes (HOM) characteristics under cryogenic conditions (2K) are being done at the Accelerating Module Test Facility (AMTF) by the IFJ-PAN Team in collaboration with DESY groups. More than 50 % of the cavities have been already produced and 30 % of the whole amount were measured during either cavity vertical tests or module tests. We present first statistics of these measurements and analyze the efficiency of HOM extraction.

Poster THPP022 [0.801 MB]

THPP025

RF Design and Low Power Measurements of a Nose-Cone Single Gap Buncher Cavity

pick-up, coupling, factory, simulation

888

O. González, I. Bustinduy, N. Garmendia, P.J. González, L. Muguira, J.L. Muñoz, A. Zugazaga
ESS Bilbao, Zamudio, Spain

A nose-cone single-gap buncher cavity for the Medium Energy Beam Transport (MEBT) has been fully designed, manufactured and measured under low-power conditions at ESS-Bilbao. The main steps of the design process are first reviewed. Second, the cavity is thoroughly measured and characterized by means of an automatic test procedure based on the bead-pull technique. Third, the simulated and measured results obtained for the main figures of merit are compared. Specifically, the results for the resonant frequency, the coupling and quality factors, the electric field profile, the R over Q ratio, the transit time factor and the tuning range are carefully analysed.

THPP027

Commissioning of the Linac4 Low Level RF and Future Plans

LLRF, linac, klystron, DTL

892

P. Baudrenghien, J. Galindo, G. Hagmann, J. Noirjean, D. Stellfeld, D. Valuch
CERN, Geneva, Switzerland

Linac4 is a new 86-m long normal-conducting linear accelerator that will provide 160 MeV H⁻ to the CERN PS Booster (PSB), and replace the present 50 MeV proton Linac2. The Low Level RF (LLRF) system has to control the RFQ, two choppers, three bunching cavities, twenty two accelerating cavities and one debuncher in the transfer line to the PSB. To optimize the transfer into the 1 MHz PSB bucket, the machine includes fast choppers (synchronized with the PSB RF) and a voltage modulation of the last two cavities that will provide Longitudinal Painting for optimum filling. The commissioning in the tunnel with beam has started in October 2013. So far the part consisting of the RFQ, the three bunching cavities, and the first DTL is operational. The rest of the machine will be progressively commissioned till end 2015. The paper presents the LLRF system. First results from the commissioning (with a prototype regulation system) are shown and the more sophisticated algorithms under development are presented.

THPP028

Design and Beamloading-Simulations of a Pre-Bunching Cavity for the CLIC Drive Beam Injector

beam-loading, simulation, coupling, electron

895

M. Dayyani Kelisani, S. Döbert, H. Shaker
CERN, Geneva, Switzerland
H. Shaker
IPM, Tehran, Iran

The CLIC project is developing a multi-TeV center-of-mass electron-positron collider based on high-gradient, room-temperature accelerating structures and a novel two-beam RF power generation scheme. The RF power for the CLIC accelerating structures is provided by the so-called drive beam which is a low energy, high current electron beam. The drive beam will be generated from a high current (up to 5 A) pulsed (142μs) thermionic electron gun and then followed by a bunching system. The bunching system is composed of three sub-harmonic bunchers operating at a frequency of 499.75 MHz, a pre-buncher and a traveling wave buncher both operating at 999.5MHz. The pre-buncher cavity, which has a great importance on minimization the satellite population, should be designed with special consideration of the high beam loading effect due to the high current beam crossing the cavity. In this work we report on RF design, analytical beam loading calculations and simulations for the CLIC drive beam injector pre-buncher cavity.

THPP029

Electropolishing Simulation on Full Scale Radio Frequency Elliptical Structures

simulation, cathode, niobium, radio-frequency

898

L.M.A. Ferreira
CERN, Geneva, Switzerland
H. Rana, J.A. Shirra
Loughborough University, Leicestershre, United Kingdom

This paper describes a methodology to simulate the electropolishing of a full scale radio frequency (RF) accelerating elliptical cavity through data acquired by means of a rotating disc electrode (RDE) in a three electrode set-up. The method combines laboratorial data from the RDE with computational simulation performed with Comsol Multiphysics® either for the primary and secondary current distribution as well as to account for the local effect of hydrodynamic perturbations. The results are compared with experimental data from the electropolishing of niobium 704 MHz and five cell cavity from the Superconducting Proton Linear Accelerator (SPL) R&D project at CERN.

Poster THPP029 [0.177 MB]

THPP031

Plans for an ERL Test Facility at CERN

cryomodule, electron, SRF, linac

905

E. Jensen, O.S. Brüning, R. Calaga, K.M. Schirm, R. Torres-Sanchez, A. Valloni
CERN, Geneva, Switzerland
K. Aulenbacher
IKP, Mainz, Germany
S.A. Bogacz, A. Hutton
JLab, Newport News, Virginia, USA
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The baseline electron accelerator for LHeC and one option for FCC-he is an Energy Recovery Linac. To prepare and study the necessary key technologies, CERN has started – in collaboration with JLAB and Mainz University – the conceptual design of an ERL Test Facility (ERL-TF). Staged construction will allow the study under different conditions with up to 3 passes, beam energies of up to about 1 GeV and currents of up to 50 mA. The design and development of superconducting cavity modules, including coupler and HOM damper designs, are also of central importance for other existing and future accelerators and their tests are at the heart of the current ERL-TF goals. The ERL-TF could also provide a unique infrastructure for several applications that go beyond developing and testing the ERL technology at CERN. In addition to experimental studies of beam dynamics, operational and reliability issues in an ERL, it could equally serve for quench tests of superconducting magnets, as physics experimental facility on its own right or as test stand for detector developments. This contribution will describe the goals and the concept of the facility and the status of the R&D.

THPP037

Commissioning and Operational Experience Gained with the Linac4 RFQ at CERN

rfq, linac, emittance, ion

926

C. Rossi, L. Arnaudon, P. Baudrenghien, G. Bellodi, O. Brunner, J. Hansen, J.-B. Lallement, A.M. Lombardi, J. Noirjean
CERN, Geneva, Switzerland
M. Desmons, A. France, O. Piquet
CEA/DSM/IRFU, France

The installation of Linac4 has started in 2013 with the 3 MeV Front End, aiming at delivering a fully commissioned 160 MeV H⁻ beam by 2016. During summer 2013 the H⁻ ion source, a clone of the first prototype, and the Low Energy Beam Transport lines have been installed in the Linac4 tunnel followed shortly by the Radiofrequency Quadrupole accelerator (RFQ), operating at the RF frequency of 352.2 MHz and which accelerates the ion beam to the energy of 3 MeV. The RFQ, which had already been commissioned at the 3 MeV Test Stand, was this time driven by a fully digital LLRF system. This paper reports the result of the bead-pull field check performed after the installation in the tunnel, the experience gained during recommissioning and the results of field characterization as a function of the water temperature in the RFQ cooling channels, showing how the accelerating field can be adjusted by simply tuning the different cavity modules.

THPP039

Electron Beam Welding and Vacuum Brazing Characterization for SRF Cavities

vacuum, niobium, electron, interface

932

N. Valverde Alonso, S. Atieh, I. Aviles Santillana, S. Calatroni, O. Capatina, L.M.A. Ferreira, F. Pillon, M. Redondas Monteserin, T. Renaglia, K.M. Schirm, T. Tardy, A. Vacca
CERN, Geneva, Switzerland

In the framework of the SPL R&D effort at CERN, development design efforts study the joining of dissimilar metals: bulk niobium for the superconducting RF cavities and stainless steel (316LN) or titanium alloys (Ti-6Al-4V and Nb55Ti) for the cryostats. Joining techniques of electron beam welding (EBW) and vacuum brazing are particularly important for these applications. These processes have been used in the accelerator community and developed into generally accepted “best practice”. Studies were performed to update the existing knowledge, and comprehensively characterise these joints via mechanical and metallurgical investigations using modern available technologies. The developed solutions are described in detail, some currently being applied uniquely at CERN.

Poster THPP039 [5.324 MB]

THPP040

A Compact High-Frequency RFQ for Medical Applications

rfq, linac, proton, quadrupole

935

M. Vretenar, A. Dallocchio, V.A. Dimov, M. Garlaschè, A. Grudiev, A.M. Lombardi, S.J. Mathot, E. Montesinos, M.A. Timmins
CERN, Geneva, Switzerland

In the frame of a new program for medical applications, CERN has designed and is presently constructing a compact 750 MHz Radio Frequency Quadrupole to be used as injector for hadron therapy linacs. The RFQ reaches an energy of 5 MeV in only 2 meters; it is divided into four standardized modules of 500 mm, each equipped with 12 tuner ports and one RF input. The inner quadrant radius is 46 mm and the RFQ has an outer diameter of 134 mm; its total weight is only 220 kg. The beam dynamics and RF design have been optimized for reduced length and minimum RF power consumption; construction techniques have been adapted for future industrial production. The multiple RF ports are foreseen for using either 4 solid-state units or 4 IOT’s as RF power sources. Although hadron therapy requires only a low duty cycle, the RFQ has been designed for 5% duty cycle in view of other uses. This extremely compact and economical RFQ design opens several new perspectives for medical applications, in particular for PET isotopes production in hospitals with two coupled high-frequency RFQs reaching 10 MeV and for Technetium production for SPECT tomography with two RFQs followed by a DTL.

THPP046

SRF Highbay Technical Infrastructure for FRIB Production at Michigan State University

SRF, cryomodule, vacuum, controls

954

L. Popielarski, F. Casagrande, C. Compton, T. Elkin, A. Fila, P.E. Gibson, M. Hodek, L. Hodges, I.M. Malloch, C. Nguyen, R. Oweiss, J.P. Ozelis, J. Popielarski, C. Thronson, D.R. Victory, T. Xu
FRIB, East Lansing, Michigan, USA
M. Leitner
LBNL, Berkeley, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE- SC0000661
Michigan State University (MSU) has funded the construction of a new 27,000 square foot high bay building to house the Superconducting Radio Frequency (SRF) infrastructure for the Facility for Rare Isotope Beams (FRIB) production requirements. The construction has been completed and beneficial occupancy began on May 19th, 2014. The new SRF highbay includes over 4,000 square feet of cleanroom and chemistry facility space, automated cavity etch tools, ultra pure water systems, cold mass component inspection area, hydrogen degassing furnace, SRF testing capabilities for three vertical test Dewars and two horizontal cryomodule test bunkers with dedicated helium refrigeration system. The status of the technical equipment design, installation and commissioning will be presented.

THPP048

Design of a Compact Lever Slow/Fast Tuner for 650 MHz Cavities for Project X

operation, resonance, simulation, SRF

957

I.V. Gonin, E. Borissov, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Fermilab is developing 5-cell elliptical 650 MHz β=0.6 and β=0.9 cavities for Project X. A compact fast/slow lever tuner intended for both types of cavities has been developed for final tuning of the resonance frequency of the cavity after cooling down and to compensate the resonance frequency variations of the cavity during operation coming from liquid helium pressure fluctuations. The updated helium vessel (presented at this conference) is equipped with the tuner located at one of the end of the cavity. The tuner design and results of ANSYS analysis of their properties are presented.

THPP049

Design of 162.5 MHz CW Main Coupler for RFQ

rfq, simulation, coupling, high-voltage

960

S. Kazakov, T.N. Khabiboulline, V. Poloubotko, O.V. Pronitchev, J. Steimel, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Project X Injector Experiment (PXIE) at Fermilab will utilize 162.5 MHz CW RFQ accelerating cavity. Design of new main power coupler for PXIE RFQ is reported. Two identical couplers are supposed to deliver approximately 100 kW total CW RF power to RFQ. Unique design of the coupler allows providing DC bias for multipactor suppression. Results of RF and thermal simulations along with mechanical design are presented.

THPP050

Status of 325 MHz Main Couplers for PXIE

Windows, vacuum, multipactoring, pick-up

963

S. Kazakov, B.M. Hanna, T.N. Khabiboulline, V. Poloubotko, O.V. Pronitchev, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

The Project X Injector Experiment (PXIE) at Fermilab will include one cryomodule with eight 325 MHz single spoke superconductive cavities (SSR1). Each cavity requires approximately 2 kW CW RF power for 1 mA beam current operation. A future upgrade will require up to 8 kW RF power per cavity. Fermilab has designed, procured and tested two prototype couplers for the SSR type cavities. Status of the 325 MHz main coupler development for PXIE is reported.

THPP051

Design of a Quasi-Waveguide Multicell Deflecting Cavity for the Advanced Photon Source

HOM, dipole, impedance, damping

966

A. Lunin, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
A. Zholents
ANL, Argonne, Ilinois, USA

This paper reports the electromagnetic design of a 2815 MHz Quasi-waveguide Multicell Resonator (called QMiR) being considered as a transverse RF deflecting cavity for the Advanced Photon Source’s (APS) Short Pulse X-ray project. QMiR forms a trapped dipole mode inside a beam vacuum chamber while High Order Modes (HOM) are heavily loaded. It results a sparse HOM spectrum, makes HOM couplers unnecessary and allows to simplify the cavity mechanical design. The form of electrodes is optimized for producing 2 MV of deflecting voltage and keeping low peak surface electric and magnetic fields of 54 MV/m and 75 mT respectively. Results of detailed EM analysis, including HOM damping at the actual geometry of beam vacuum chamber, will be presented.

Poster THPP051 [1.250 MB]

THPP054

Study of Coupler's Effect in Third Harmonic Section of LCLS-II SC Linac

cryomodule, linac, emittance, HOM

969

A. Saini, A. Lunin, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The Linac Coherent Light Source (LCLS) is an x-ray free electron laser facility. The proposed upgrade of the LCLS facility is based on construction of 4 GeV superconducting (SC) linac which will use two stage bunch compression scheme in order to achieve short bunches with high peak current. In order to reduce non-linear effects in first bunch compressor, third harmonic section is utilized to linearize longitudinal phase space of the beam. However, transverse phase space of beam may get distorted due to coupler RF kicks and coupler wake kicks resulting from the asymmetry of input and HOM couplers in 3.9 GHz cavity. In this paper, we discuss coupler's effects and estimate resulting emittance dilution in third harmonic section. Local compensation of coupler kicks using different orientation of cavities are also addressed.

THPP057

Results of Cold Tests of the Fermilab SSR1 Cavities

cryomodule, radiation, SRF, resonance

979

A.I. Sukhanov, M.H. Awida, P. Berrutti, E. Cullerton, B.M. Hanna, A. Hocker, T.N. Khabiboulline, O.S. Melnychuk, D. Passarelli, R.V. Pilipenko, Y.M. Pischalnikov, L. Ristori, A.M. Rowe, W. Schappert, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

Fermilab is currently building the Project X Injector experiment (PXIE). The PXIE linac will accelerate a 1 mA H⁻ beam up to 30 MeV and serve as a testbed for validation of Project X concepts and mitigation of technical risks. A cryomodule of eight superconducting RF Single Spoke Resonators of type 1 (SSR1) cavities operating at 325 MHz is an integral part of PXIE. Ten SSR1 cavities were manufactured in industry and delivered to Fermilab. We discuss tests of nine bare SSR1 cavities at the Fermilab Vertical Test Stand (VTS). Recently, one of the SSR1 cavities was welded inside a helium jacket. Results of the test of this cavity in the Fermilab Spoke Test Cryostat (STC) are shown. We report on the measured performance parameters of SSR1 cavities achieved during the tests.

THPP058

A Review of Emittance Exchanger Beamlines: Past Experiments and Future Proposals

emittance, electron, laser, experiment

982

J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Emittance exchangers (EEX) are advanced phase space manipulation schemes where the transverse phase space of the electron beam is exchanged with the longitudinal phase space. The first experimentally demonstrated concept of the emittance exchanger at the A0 photoinjector at Fermilab used a transverse deflecting cavity (TDC) sandwiched between two doglegs. In this talk, I will briefly review the history of the emittance exchange beamline experiments from a low charge beam without RF chirp to a high charge beam with RF chirp including collective effects such as coherent synchrotron radiation. I will also describe how shaping application have been spawned based on EEX. I will then review future schemes that has been proposed and propose two additional schemes of EEX that can be implemented in existing modern linacs. As an example, we present an improved emittance exchanger scheme that uses a TDC sandwiched between two chicanes. The significant advantage of this scheme is that it allows the use of the expensive transverse deflecting cavity for diagnostics and still allows the flexibility to use the existing beamline either as a bunch compressor or an emittance exchanger.

THPP060

Effect of Cavity Couplers Field on the Beam Dynamics of the LCLS-II Injector

simulation, HOM, emittance, cryomodule

989

A. Vivoli, A. Lunin, A. Saini, N. Solyak
Fermilab, Batavia, Illinois, USA
A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Dowell, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou
SLAC, Menlo Park, California, USA
D. Filippetto, R. Huang, C. F. Papadopoulos, H.J. Qian, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA

LCLS-II is a new light source based on a continuous wave (cw) superconducting linac to be built at SLAC. The Injector section of the linac creates the elecron beam and accelerates it up to about 100 MeV. The couplers of the accelerating cavities produce an asymmetric field resulting in a beam offset and, most importantly, in a significant transverse emittance dilution, if not compensated. In this paper we describe the simulations of the LCLS-II injector taking into account the cavity couplers effect and some mitigation techniques to reduce its impact on the beam quality.

THPP062

BERLinPro SRF Gun Notch Filter Investigations

gun, cathode, SRF, resonance

995

E.N. Zaplatin
FZJ, Jülich, Germany
J. Knobloch, A. Neumann
HZB, Berlin, Germany

BERLinPro is an approved ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity (1300 MHz, β=1) for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.8 MeV kinetic energy while limited by fundamental power coupler performance to about 230 kW forward power. The RF and beam dynamics gun cavity features 1.4 λ/2 cell resonator. To protect a cathode housing from RF power propagation from the cavity cells and to reduce its component heating a high-frequency notch filter was investigated. We present results of different schemes of choke cell combinations to optimize filter parameters. The goal for the filter design was the RF power attenuation better than -30 dB in the wide frequency range.

THPP067

Status of the SPP RFQ Project

rfq, ion, ion-source, diagnostics

1004

G. Turemen, B. Yasatekin
Ankara University, Faculty of Sciences, Ankara, Turkey
A. Alacakir
TAEK, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA
H. Yildiz
Istanbul University, Istanbul, Turkey

The SPP project at TAEA will use 352.2 MHz 4-vane Radio Frequency Quadrupole (RFQ) to accelerate H⁺ ions from 20 KeV to 1.5 MeV. With the design already complete the project is at the test production phase. To this effect, a so called "cold model" of 50cm length has been produced to validate the design approach, to perform the low power RF tests and to evaluate possible production errors. This paper will report on the current status of the low energy beam transport line (LEBT) and RFQ cavity of the SPP project. It will also discuss the design and manufacturing of the RF power supply and its transmission line. In addition, the test results from some of the LEBT components will be shown and the final RFQ design will be shared.

Poster THPP067 [6.947 MB]

THPP068

Cold Power Tests of the SC 325 MHz CH-Cavity

controls, linac, ion, heavy-ion

1007

M. Busch, M. Amberg, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany

Funding: Work supported by GSI, BMBF Contr. No. 06FY7102
At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed, built and first tests have successfully been performed. The cavity is determined for a 11.4 AMeV, 10 mA ion beam at the GSI UNILAC. Consisting of 7 gaps this resonator is envisaged to deliver a gradient of 5 MV/m. Novel features of this structure are a compact design, low peak fields, improved surface processing and power coupling. Furthermore a tuner system based on bellow tuners driven by a stepping motor and a piezo actuator and attached inside the resonator will control the frequency. In this contribution measurements executed at 4 K and 2 K at the cryo lab in Frankfurt will be presented.

Poster THPP068 [1.449 MB]

THPP072

BERLinPro Booster Cavity Design, Fabrication and Test Plans

cryomodule, booster, SRF, linac

1019

A. Burrill, W. Anders, A. Frahm, J. Knobloch, A. Neumann
HZB, Berlin, Germany
G. Ciovati, P. Kneisel, L. Turlington
JLab, Newport News, Virginia, USA

The BERLinPro project, a 100 mA, 50 MeV superconducting RF (SRF) Energy Recovery Linac (ERL) is under construction at Helmholtz-Zentrum Berlin for the purpose of studying the technical challenges and physics of operating a high current, c.w., 1.3 GHz ERL. This machine will utilize three unique SRF cryomodules for the injector, booster and linac module respectively. The booster cryomodule will contain three 2-cell SRF cavities, based on the original design by Cornell University, and will be equipped with twin 115 kW RF power couplers in order to provide the appropriate acceleration to the high current electron beam. This paper will review the status of the fabrication of the 4 booster cavities that have been built for this project by Jefferson Laboratory and look at the challenges presented by the incorporation of fundamental power couplers capable of delivering 115 kW. The test plan for the cavities and couplers will be given along with a brief overview of the cryomodule design.

THPP074

Superconducting Nano-Layer Coating Without Insulator

1026

T. Kubo
KEK, Ibaraki, Japan

Last year, we submitted a theoretical paper on a multilayered structure with a single superconductor layer and a single insulator layer formed on a bulk superconductor, where the magnetic field on the interface of the bulk superconductor were derived with a rigorous calculation of the magnetic field attenuation in the multilayered structure and the general formula for the vortex penetration field of the superconductor layer were computed in terms of the force acting on a vortex. Using the formulae, a combination of the thicknesses of superconductor and insulator layers that can realize the enhanced field limit can be found for any given materials. Then our results on optimum combinations of layer thicknesses and resultant field limits were reproduced by other group, where they carried out the same computation in terms of energy. To confirm these theoretical implications, experiments to measure vortex penetration fields of multilayered superconductors are planned. Theoretical studies to help the planned experiments are also in progress. In this presentation we will explain our ongoing experimental and theoretical studies.
T. Kubo, Y. Iwashita, T. Saeki, Applied Physics Letters 104, 032603 (2014);
proceedings of SRF 2013, Paris, France (2013), p. 427;
proceedings of IPAC13, Shanghai, China (2013), p. 2343.

THPP075

Development of Superconducting Spoke Cavity for Electron Accelerators

simulation, electron, multipactoring, acceleration

1030

T. Kubo, T. Saeki
KEK, Ibaraki, Japan
E. Cenni, H. Fujisawa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
R. Hajima, M. Sawamura
JAEA, Ibaraki-ken, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have launched a development program of a superconducting spoke cavity for electron acceleration, in order to realize a compact industrial-use X-ray source with the laser-Compton scattering. Efforts for optimizing a cavity design by the electromagnetic field simulation, tracking of multipactor electrons and mechanical property calculations have been continued so far. The optimization processes reached the final stage, and studies toward fabrication processes started. In this presentation, we will show results and processes of the optimization. Attempts to fabricate the spoke cavity, which have just begun, will also be presented.

THPP077

Fast Tuner Performance for a Double Spoke Cavity

operation, simulation, controls, SRF

1034

N. Gandolfo, S. Bousson, S. Brault, P. Duchesne, P. Duthil, G. Olry, D. Reynet
IPN, Orsay, France
C. Darve, M. Lindroos
ESS, Lund, Sweden

IPN Orsay is developing the low-beta double Spoke cavities cryomodule for the ESS. In order to compensate resonant frequency variations of each cavity during operation, a deformation tuner has been studied and two of them have been built. The typical perturbations are coming from LHe saturated bath pressure variations as well as microphonics and Lorentz force detuning (LFD). In this paper, the tuner performance of the double Spoke cavity is presented.

THPP078

Troubleshooting and Performances of Type-B Spiral2 Series Cryomodule

cryomodule, coupling, pick-up, resonance

1037

D. Longuevergne, F. Chatelet, C. Commeaux, N. Gandolfo, D. Grolet, C. Joly, J. Lesrel, R. Martret, G. Michel, G. Olry, L. Renard, A. Stephen, P. Szott
IPN, Orsay, France

SPIRAL2 aims at building a multi-purpose facility dedicated to nuclear physics studies, including the production of rich-neutrons isotopes. The multi-beam linear accelerator is composed of superconducting accelerating modules operating at 4.2K and warm focusing magnets. IPN Orsay is in charge of the high energy (Type-B) accelerating modules, each hosting two superconducting 88 MHz quarter-wave resonators made of bulk Niobium operating at an accelerating gradient of 6.5 MV/m (β=0.12). The first Type-B series cryomodule has been validated in April 2013. Since then, four additional cryomodules have been validated in a row showing a very high-quality and reliable assembly procedure. Some of encountered problems (tuner hysteresis, magnetic shielding,) and associated solutions will be presented. Moreover, a comparison of cavity performances between vertical cryostat and cryomodule tests will be done.

THPP079

Prototyping Progress of SSR1 Single Spoke Resonator for RAON

target, simulation, vacuum, heavy-ion

1

H.J. Cha, M.O. Hyun, D. Jeon, H.C. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea

The fabrication of prototypes for four different types of superconducting cavities (QWR, HWR, SSR1, and SSR2) for the Korean heavy ion accelerator, “RAON” is in progress. In this presentation, we report the current status of the SSR1 cavity (β=0.3 and f=325 MHz) prototype fabrication based on the technical designs. The issues when forming the niobium cavities such as pressing, machining, electron beam welding are reviewed. The RF testing for the prototypes, which will be done in near future, is also discussed.

THPP089

High Power Conditioning of Annular-Ring Coupled Structures for the J-PARC Linac

vacuum, operation, linac, coupling

1053

H. Ao, T. Ito, Y. Nemoto, H. Oguri, N. Ouchi, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
H. Asano
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
Z. Fang, K. Futatsukawa, K. Nanmo, T. Sugimura
KEK, Ibaraki, Japan

The linac of Japan Proton Accelerator Research Complex (J-PARC), which is an injector to a 3-GeV synchrotron, comprised a 3-MeV RFQ, 50-MeV DTLs and 181-MeV Separated-type DTLs. From September 2013, 25 annular-ring coupled structure (ACS) cavities were additionally installed to increase the linac beam energy up to 400 MeV and achieve 1-MW beam power of the 3-GeV synchrotron. After installation work the high power conditioning was started from December 2013 and most of the ACS cavities were conditioned within three weeks. We passed through some troubles and finally finished conditioning all the cavities until the middle of January 2014. In this paper, we present the conditioning results and how to handle the issue in the conditioning process.

Slides THPP089 [7.756 MB]

THPP091

Installation and Performance Check of Beam Monitors for Energy Upgraded J-PARC Linac

linac, operation, quadrupole, acceleration

1059

A. Miura, K. Hasegawa, H. Oguri, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
M. Ikegami
FRIB, East Lansing, Michigan, USA
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
T. Maruta
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Miyao
KEK, Ibaraki, Japan

An energy upgrade project has started to achieve the design beam power of 1 MW at the exit of the downstream synchrotron in the J-PARC Linac since 2009. In the upgraded project, a beam energy in the Linac has increased from present 181 MeV to 400 MeV using the additional 21 annular-ring coupled structure (ACS) cavities. The new beam monitors as the beam current monitors, the phase monitors, the beam position monitors, the transverse profile monitors (wire scanner monitors) and the longitudinal profile monitors (bunch shape monitors) for the part where the ACS cavities were installed were designed, fabricated and calibrated. Till the end of November, 2013, all beam monitors were completed to be installed. From the middle of December, we started the beam commissioning to achieve the beam energy as 400 MeV, as well as to confirm the beam monitor functioning. We achieved the 400 MeV beam acceleration at the middle of January, 2014 using newly installed beam monitors. This paper describes the beam monitor installation, calibration and the beam commissioning results of beam monitor functioning.

THPP093

Combined System of Optical Inspection and Local Grinder

injection, brightness, controls, superconducting-cavity

1065

Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano, T. Kubo, K. Watanabe, Y. Yamamoto
KEK, Ibaraki, Japan

Optical inspections on superconducting accelerating tubes have been playing an important role on improving their accelerating gradients. Instead of treatments on whole cavity inner surfaces to eliminate the found defects on the surfaces, the local grinding method succeeds to remove them efficiently. A combined system of the optical inspection and the local Grinding machines are fabricated. The overview of the system will be presented.

THPP097

3D Effects in RFQ Accelerators

rfq, simulation, quadrupole, emittance

1077

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

RFQ accelerators are usually designed and modeled with standard codes based on electrostatic approximations. Recent examples show that this approach fails to accurately predict the performance for 4-rod RFQs: 3D RF effects near the vane ends can noticeably influence the beam dynamics. The same applies to any RFQ where the quadrupole symmetry is broken, e.g., 4-vane RFQ with windows. We analyzed two 201.25-MHz 4-rod RFQs – one recently commissioned at FNAL and a new design for LANL – using 3D modeling with CST Studio. In both cases the manufacturer CAD RFQ model was imported into CST. The electromagnetic analysis with MicroWave Studio (MWS) was followed by beam dynamics modeling with Particle Studio (PS). For the LANL RFQ with duty factor up to 15%, a thermal-stress analysis with ANSYS was also performed. The simulation results for FNAL RFQ helped our Fermilab colleagues fix the low output beam energy. The LANL RFQ design was modified after CST simulations indicated insufficient tuning range and incorrect output energy; the modified version satisfies the design requirements.

THPP098

Vertical Electropolishing of Nb Coupon Cavity and Surface Study of the Coupon Samples

cathode, experiment, target, superconducting-RF

1080

V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
K. Ishimi
MGI, Chiba, Japan

We have been carrying out vertical electropolishing (VEP) of 1.3 GHz Nb cavities for the ILC for 2 years. In this article we present VEP of a single cell Nb coupon cavity containing 6 Nb disk type coupons located at beam pipes, irises and equator positions of the cavity. VEP experiments were performed using our special ninja-cathode newly developed and a straight rod cathode in order to observe and compare the homogeneity of electropolishing (EP) and surface quality on the entire surface of the single cell cavity. EP current was measured for the individual coupons under different EP conditions in order to study the EP phenomenon on the different positions of the cavity. The surfaces of the coupons were analyzed by x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDX). This article describes VEP and surface analysis results in detail.

THPP099

Status of Superconducting Cavity and Cryomodule Development at MHI

cryomodule, vacuum, niobium, superconducting-cavity

1084

T. Yanagisawa, H. Hara, N. Ikeda, K. Sennyu
MHI, Hiroshima, Japan

MHI's activities for ｓuperconducting accelerator are reported. MHI had developed several procedure and method of ILC cavity production for stable quality and cost reduction. And we had fabricated and installed cryomodules for ILC and ERL R&D. These activities are reported in detail.

THPP100

Result of MHI 2-Cell Seamless Dumb-Bell Cavity Vertical Test

superconducting-cavity, linac, vacuum, electron

1087

K. Okihira, H. Hara, N. Ikeda, F. Inoue, K. Sennyu
MHI, Kobe, Japan
R.L. Geng, R.A. Rimmer
JLab, Newport News, Virginia, USA
E. Kako
KEK, Ibaraki, Japan

MHI have supplied several 9-cell cavities for STF (R&D of ILC project at KEK) and have been considering production method for stable quality and cost reduction, seamless dumb-bell cavity was one of them. We had fabricated a 2 cell seamless dumb-bell cavity for cost reduction and measured RF performance in collaboration with JLab, KEK and MHI. Surface treatment recipe for ILC was applied for MHI 2-cell cavity and vertical test was performed at JLab. The cavity reached Eacc=32.4MV/m after BCP and EP. Details of the result are reported.

THPP107

Study on Polishing Method of Nb Surface by Periodic Reverse Current Electrolysis With Alkali Solution

experiment, SRF, laser, operation

1102

M. Umehara
Nomura Plating Co, Ltd., Osaka, Japan
H. Hayano, T. Saeki
KEK, Ibaraki, Japan

Currently, electropolising method is thought to be the best method for the final surface preparation of superconducting RF cavity to obtain high gradient. In this conventional electropolising method, the electrolyte is the mixture of fluoric and sulfuric acids. Therefore, the operation of this method is dangerous, and the equipment becomes expensive because all parts should be made of high density polyethylene or fluorocarbon resin to avoid metallic parts which suffers from corrosion by electrolyte. Moreover, sulfur is produced as byproduct in the electropolishing process and this causes degradation of cavity performance. In order to overcome these drawbacks, we studied new polishing method of Nb surface by periodic reverse current electrolysis with alkali solution which causes no sulfur and allows the usage of metallic parts to realize cost effective equipment. In the study, we performed experiment of Nb coupons by this new method and obtained as good surface roughness as conventional electropolishing method. In this article, we report the details of the study.

THPP109

History of Cryomodule Repairs at SNS

cryomodule, HOM, operation, linac

1108

M.P. Howell, M. Doleans, D.L. Douglas, S.-H. Kim
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, B. DeGraff, B.S. Hannah, C.J. McMahan, T.S. Neustadt, S.W. Ottaway, J. Saunders, P.V. Tyagi, D.M. Vandygriff
ORNL RAD, Oak Ridge, Tennessee, USA

The operation of the Superconducting linear accelerator (SCL) has matured and now averages less than one trip per day. The availability of the SCL including radiofrequency systems, high voltage converter modulators, controls, vacuum and other support systems over the last three years is approximately 98%. The SNS has been in operation for ten years including the commissioning period. In support of achieving the stability of operation, multiple cryomodule repairs have been performed. Repairs to cryomodules have included instruments, helium leaks, valve actuators, cavity tuners, insulating vacuum repairs and upgrades, power supplies, higher order mode (HOM) feedthroughs, coupler windows, and coupler cooling components. Performance degradation has been experienced in multiple cavities. This has been corrected by thermal cycling the cryomodules with the affected cavities. Only two cavities have displayed slight permanent degradation that could not be corrected by thermal cycling. Repairs made to the SNS cryomodule will be detailed in this paper.

THPP112

Multipacting Optimization of a 750 MHz RF Dipole

dipole, simulation, electron, collider

1111

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.

THPP119

Stabilization of Beam Performance due to Improvement of the Precise Temperature Regulation System of the SACLA Injector

laser, controls, power-supply, feedback

1131

T. Asaka, T. Hasegawa, H. Maesaka, Y. Otake, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The temperature of rf cavities in the SACLA injector have to be precisely controlled to generate stable electron beam for XFEL users. To maintain the rf voltage and phase in the each cavity, the temperatures of all the cavities were kept within 28±0.04˚C by controlling the cooling water temperature. AC power supply of the controller to heat the cooling water was operated at 2Hz by PWM control with alternatively tuning on and off. The correlation between beam position variation and a leakage magnetic field due to applying the heater current of an AC power supply was found out. Although the cooling water temperature was controlled less than ±40mK, the laser intensity was affected by slight temperature drift. Therefore, thermometer modules were replaced to more precise ones with 1mK resolution. A new temperature regulation system using a continuous level control with DC power supply was installed. The fast fluctuation of the magnetic field leak by the heater current due to the PWM control was removed. Consequently, the beam position jitter in an undulator section was reduced to less than one-third and the laser position variation was suppressed within 20μm.

THPP120

Status of Radio-Frequency (RF) Deflectors at Radiabeam

electron, simulation, impedance, laser

1134

L. Faillace, R.B. Agustsson, J.J. Hartzell, A.Y. Murokh, S. Storms
RadiaBeam, Santa Monica, California, USA

Radiabeam Technologies recently developed an S-Band normal-conducting Radio-Frequency (NCRF) deflecting cavity for the Pohang Accelerator Laboratory (PAL) in order to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 135 MeV electron beam parameters. The 1m-long PAL deflector is designed to operate at 2.856 GHz and features short filling time and femtosecond resolution. At the end of 2012, we delivered an X-band Traveling wave RF Deflector (XTD) to the ATF facility at Brookhaven National Lab. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. The XTD is currently being assembled at ATF for high-power operation and conditioning results will be reported soon.

THPP121

Injector System for the IR-FEL at RRCAT

beam-loading, linac, electron, FEL

1137

L. Faillace, R.B. Agustsson
RadiaBeam, Santa Monica, California, USA
A. Kumar, K.K. Pant
RRCAT, Indore (M.P.), India

An infrared (IR) free-electron laser (FEL) has been proposed to be built at the Raja Ramanna Centre for Advanced Technology (RRCAT). RadiaBeam is currently involved in the design of the RRCAT FEL's injector system. The injector will deliver an electron beam with a variable energy (from 15 up to 40 MeV) and 1.5 nC at 36.6 MHz repetition rate. We show here the beam dynamics of the beam transport through the injector as well as the RF design and mechanical model of the system.
* S. Krishnagopal et al., PRELIMINARY DESIGN OF THE PROPOSED IR-FEL IN INDIA, RRCAT, Indore, M.P. 452013, India

THPP122

Development of Superconducting Cavities and Related Infrastructure for High Intensity Proton Linac for Spallation Neutron Source

niobium, laser, linac, proton

1140

S.C. Joshi, J. Dwivedi, P.D. Gupta, P.R. Hannurkar, V. Jain, P. Khare, P.K. Kush, G. Mundra, A. Puntambekar, S. Raghvendra, S.B. Roy, P. Shrivastava
RRCAT, Indore (M.P.), India

Raja Ramanna Centre for Advanced Technology has taken up a program on R&D activities of a 1 GeV, high intensity superconducting proton linac for a spallation neutron source. The proton linac will require a large number of superconducting Radio Frequency cavities ranging from low beta spoke resonators to medium and high beta multi-cell elliptical cavities at different RF frequencies. A dedicated facility is being set up for development of multi-cell superconducting cavities and their performance characterization. 1.3 GHz single-cell niobium cavities have been developed to establish the fabrication procedure. These cavities has exhibited high quality factor with an accelerating gradients up to 37 MV/m. A novel technique of laser welding of 1.3 GHz niobium cavity has been developed and demonstrated performance comparable to electron beam welded cavity. A dedicated facility for SCRF cavity forming, machining, electron beam welding, RF characterization, cavity tuning and cavity processing is being set up. To characterize a SCRF cavity at 2K, a vertical test stand has been developed and a horizontal test stand has been designed.

THPP123

Experience of Operation of the Electron Linear Accelerator Based on Parallel Coupled Accelerating Structure

electron, controls, gun, multipactoring

1144

A.E. Levichev, A.M. Barnyakov, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
Y.D. Chernousov
ICKC, Novosibirsk, Russia
V. Ivannikov, I.V. Shebolaev
ICKC SB RAS, Novosibirsk, Russia

An electron linear accelerator based on parallel coupled accelerating structure was developed and produced by Budker Institute of Nuclear Physics SB RAS and Institute of Chemical Kinetics and Combustion SB RAS. Short and long versions of the accelerating structure at 2450 MHz were built. For easy disassembly electrical and vacuum connections of the first (short) structure were made using indium seals. The second structure was brazed. Now the accelerator is in operation and used to study the accelerating and RF technologies. In the report the features of the accelerator are presented, including the design and characteristics of RF antenna and solid-state switch for the electron gun. Test results of the long parallel coupled accelerating structure are discussed. Observations made on the short structure surface after it had been opened are depicted. Now the short structure undergoes certain modifications in order to accelerate higher beam currents.

THPP124

Wakefields in the Superconducting RF Cavities of LCLS-II

linac, wakefield, electron, niobium

1147

K.L.F. Bane, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
A. Romanenko, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
The superconducting cavities in the linacs of LCLS-II are designed to operate at 2K, where cooling costs are very expensive. In addition to an unavoidable static load and the dynamic load of the fundamental 1.3 GHz accelerating rf, there will be higher order mode (HOM) power deposited by the beam. Due to the very short bunch length the LCLS-II beam spectrum extends into the THz range. Ceramic absorbers, cooled to 70K and located between cryomodules, are meant to absorb much of this power; understanding their effectiveness, however, is a challenging task. In this report we calculate the amount of power radiated by the beam in the different portions of the linac as the bunch length is changed by the bunch compressors. We consider both the steady state radiation as well as transients that arise at the beginning of the linac structures. In addition, transitions due to changes in the vacuum chamber aperture at the ends of the linacs are also considered. Finally, under the assumption that all the wake power ends up in the SRF cavity walls, we estimate the wall heating and the possibility of breaking the Cooper pairs and quenching the cavities.

THPP125

Super-Compact SLED System Used in the LCLS Diagnostic System

electron, coupling, klystron, impedance

1151

J.W. Wang, S.G. Tantawi, C. Xu
SLAC, Menlo Park, California, USA

Funding: * Work supported by Department of Energy contract DE–AC03–76SF00515.
At SLAC, we have designed and installed an X-band radio-frequency transverse deflector system at the LCLS for measurement of the time-resolved lasing effects on the electron beam and extraction of the temporal profile of the pulses in routine operations. We have designed an X-Band SLED system capable design to augment the available klystron power and to double the kick.

THPP126

Design of the High Repetition Rate Photocathode Gun for the CLARA Project

gun, simulation, multipactoring, electron

1155

B.L. Militsyn, L.S. Cowie, P. Goudket, J.W. McKenzie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov, A.K. Skasyrskaya
RAS/INR, Moscow, Russia

The CLARA injector is required to deliver ultrashort singe electron pulses with a charge of 250 pC following with a repetition rate of 100 and/or 400 Hz. It should also provide 2 us trains of twenty 25 pC pulses with a repetition rate 100 Hz. To meet this challenge, a 1.5 cell S-band photocathode gun with a field of up to 120 MV/m and coaxial coupling has been chosen. The length of the first cell of 0.5 is decided on the basis of beam dynamic simulation with the goal to obtain optimal for CLARA parameters. In order to improve amplitude and phase stability of the RF field, the gun is equipped with RF probes, which will provide feedback to the RF system. The gun and coupler were designed to accept up to 10 MW peak and 10 kW average RF powers. Cooling will be achieved by water channels cut into the bulk of the copper. The coupler will transition from waveguide to coax using an innovative H-shaped dual feed system that cancels out any dipole mode components and allows tuning of the match. The RF and mechanical design of the CLARA high brightness photocathode gun along with beam dynamics simulations are presented in this paper.

THPP127

The Status of the Construction of MICE Step IV

solenoid, emittance, experiment, coupling

1159

S. Ricciardi
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: NSF, DOE, STFC, INFN and more
The International Muon Ionisation Cooling Experiment in its next step IV will provide the first precise measurements of emittances and first evidence of cooling in 2015. The pair of MICE "emittometers" must be in place for this, upstream and downstream of the ionization cooling module. Each required the construction of a tracker (sci-fibers) measuring muon helices in solenoid coils that surround it. Solenoid coils confine muons to spiral in all components of a ionization cooling module. The first of these, that is now ready for Step IV, will be the first of three AFC (absorber-focus coil) modules: a Li-H vessel inside its own FC "focusing" coils. Li-H and other simpler, possibly competitive, liquid and solid absorber samples are also being prepared. The assembly process is in progress. Construction, performances, lessons learned will be described. Final step V and step VI demonstration requires two more AFC modules and two re-acceerating modules, RFCC's made of RF cavities inside their own focusing CC ("coupling" coils). The choices made and challenges being faced in this longer term construction efforts simultaneosly in progress will also briefly be pointed to.
The abstract is submitted by the chair of the MICE Speakers Bureau.
The presentation would be delivered by Dr Stefania Ricciardi (RAL)
Promotion to Oral would be most welcome

THPP131

Series Superconducting Cavity Production for the HIE-ISOLDE Project at CERN

cryomodule, vacuum, niobium, pick-up

1165

M. Therasse, L. Alberty, K. Artoos, S. Calatroni, O. Capatina, A. D'Elia, N.M. Jecklin, Y. Kadi, I. Mondino, K.M. Schirm, A. Sublet, W. Venturini Delsolaro, P. Zhang
CERN, Geneva, Switzerland

In the context of the HIE-ISOLDE linac upgrade at CERN, the phase 1 planned to boost the energy of the machine from 3 MeV/u to 5 MeV/u. For this purpose, it is planned to install 2 cryomodules based on quarter waves resonators (QWRs) made by Niobium sputtering on Copper. The poster will present the different steps of the cavity series production since the reception from the industry to the cavity storage before cryomodule assembly. We will describe the cavity preparation included the resonance frequency measurement, the chemical treatment, the cavity rinsing, the Niobium coating and the RF test at 4.5K.

THPP132

Warming Rate Reduction of the SARAF RF Couplers by Application of a High Voltage Dc Bias

operation, experiment, proton, linac

1168

B. Kaizer, Y. Ben Aliz, I. Fishman, J. Rodnizki, L. Weissman
Soreq NRC, Yavne, Israel

Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the main limiting factors for long operation at high RF field values. The warming effect is, most likely, associated with multipacting in the coupler region. We have tried to suppress the multipacting discharge in the couplers by application a DC bias to their inner conductors. A bias-T, element that conducts up to 4 kW of 176 MHz RF power and provides DC insulation of the coupler inner conductor, was designed and built for this purpose. First on-line operation showed that the DC bias indeed reduces dramatically the warming rates of most of the cavities by an order of magnitude. Today, coupler warming is no longer the main factor hindering accelerator operation.

THPP133

LLRF System for the CEBAF Separator Upgrade

controls, extraction, LLRF, electron

1171

T. E. Plawski, R. Bachimanchi, C. Hovater, D.J. Seidman, M.J. Wissmann
JLab, Newport News, Virginia, USA

The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of four new 750 MHz deflecting, normal conducting cavities in the 5th pass extraction region. This system will work together with existing 499 MHz RF Separator in order to allow simultaneous delivery of the beam to four CEBAF experimental halls. The RF system employs two digital LLRF systems controlling four cavities in a vector sum. Cavity tune information of the individual cavities is also obtained using a multiplexing scheme of the forward and reflected RF signals. In this paper we will present detailed LLRF design and current status of the CEBAF 750 MHz beam extraction system.

THPP135

Recent Improvements to Software Used for Optimization of SRF Linacs

cryomodule, linac, cryogenics, SRF

1174

T. Powers
JLab, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
This work describes a software tool that allows one to vary parameters and understand the effects on the optimized costs of construction plus 10 year operations of an SRF linac. The program includes estimates for the associated cryogenic facility, and controls hardware, where operation costs includes the cost of the electrical utilities but not the labor or other costs. The software interface provides the ability to vary the cost of the different aspects of the machine as well as to change the cryomodule and cavity types. Additionally, this work will describe the recent improvements to the software that allow one to estimate the costs of energy recovery based linacs and to enter arbitrary values of the low field Qo and Qo slope. The initial goal was to convert a spreadsheet format to a graphical interface to allow the ability to sweep different parameter sets. The tools also allow one to compare the cost of the different facets of the machine design and operations so as to better understand the tradeoffs. An example of how it was used to investigate the cost optimization tradeoffs for the LCLS 2 linac will also be presented.