LINAC2014 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOIOC03	Model and Beam Based Setup Procedures for a High Power Hadron Superconducting Linac	cavity, linac, 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]

MOPP028	New Criterion for Shape Optimization of Normal-Conducting Accelerator Cells for High-Gradient Applications	factory, database, resonance, impedance	114
	K.N. Sjobak, A. Grudiev CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway
	When optimizing the shape of high-gradient accelerating cells, the goal has traditionally been to minimize the peak surface electric field / gradient, or more recently minimizing the peak modified Poynting vector / gradient squared. This paper presents a method for directly comparing these quan- tities, as well as the power flow per circumference / gradient squared. The method works by comparing the maximum tolerable gradient at a fixed pulse length and breakdown rate that can be expected from the different constraints. The paper also presents a set of 120° phase-advance cells for traveling wave structures, which were designed for the new CLIC main linac accelerating structure, and which are optimized according to these criteria.

MOPP032	Experimental Verification Towards Feed-Forward Ground Motion Mitigation at ATF2	ground-motion, quadrupole, feedback, controls	124
	J. Pfingstner, K. Artoos, C. Charrondière, S.M. Janssens, M. Patecki, Y. Renier, D. Schulte, R. Tomás CERN, Geneva, Switzerland A. Jeremie IN2P3-LAPP, Annecy-le-Vieux, France K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	Without counter measures, ground motion effects would deteriorate the performance of future linear colliders to an unacceptable level. An envisioned new ground motion mitigation method (based on feed-forward control) has the potential to improve the performance and to reduce the system cost compared to other proposed methods. For the experimental verification of this feed-forward scheme, a dedicated measurement setup has been installed at ATF2 at KEK. In this paper, the progress on this experimental verification is described. An important part of the feed-forward scheme could be already demonstrated, namely the prediction of the orbit jitter due to ground motion measurements.

MOPP035	Bead-Pull Measurement Method and Tuning of a Prototype CLIC Crab Cavity	cavity, electromagnetic-fields, coupling, 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, linac, cavity, 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.

MOPP038	Longitudinal Bunch Profile Monitoring at the ESS Linac	linac, proton, neutron, target	143
	I. Dolenc Kittelmann, B. Cheymol ESS, Lund, Sweden
	The European Spallation Source (ESS), which is currently under construction, will be a neutron source based on 5MW, 2GeV proton linac. This high intensity linac will among other beam instrumentation require longitudinal bunch profile monitors. These shall be used during the commissioning phase and start-up periods for beam dynamics optimization and beam loss reduction. The paper focuses on the preliminary studies concerning the longitudinal bunch profile monitoring at the ESS linac.

MOPP039	Dynamics of Bunches Partially Chopped with the MEBT Chopper in the ESS Linac	linac, DTL, lattice, quadrupole	146
	R. Miyamoto, B. Cheymol, R. De Prisco, M. Eshraqi, A. Ponton, E. Sargsyan ESS, Lund, Sweden I. Bustinduy ESS Bilbao, Bilbao, Spain
	The front-end of a hadron linac typically has a transient time during turning on and off and bunches in the head and tail of a pulse from this period likely have wrong parameters and a risk to cause beam losses. A risk of losses must be avoided as possible in a high power machine so these bunches are removed with deflectors called choppers in the ESS Linac. From experiences of other machines, a rise time of a chopper as fast as one RF period (2.84~ns for ESS) is challenging to achieve and not necessarily needed with no ring to inject like ESS, and hence a 10~ns rise time is planned for a chopper in the medium energy beam transport of ESS. This, however, means that several bunches receive intermediate deflections and may propagate with large trajectory excursions. This paper studies dynamics of such partially chopped bunches in detail to ensure no significant loss is caused by them.

MOPP046	On the Design of Higher Order Mode Antenna for LCLS II	HOM, cavity, coupling, higher-order-mode	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.

MOPP050	Transmission Efficiency Measurement at the FNAL 4-rod RFQ	rfq, solenoid, space-charge, ion	168
	J.-P. Carneiro, F.G. Garcia, J.-F. Ostiguy, A. Saini, R.M. Zwaska Fermilab, Batavia, Illinois, USA B. Mustapha, P.N. Ostroumov ANL, Argonne, Illinois, USA
	This paper presents measurements of the beam transmission performed on the 4-rods RFQ currently under operation at Fermilab. The beam current has been measured at the RFQ exit as a function of the magnetic field strength in the 2 LEBT solenoids. This measurement is compared with a scan performed on the Fermi Grid with the beam dynamics code TRACK. A particular attention is given to the impact, on the RFQ beam transmission, of the space-charge neutralization in the LEBT and of the field asymmetry on the 4-rods RFQ.

MOPP053	TTF-III Coupler Modification for CW Operation	operation, resonance, coupling, status	174
	I.V. Gonin, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	LCLS-II linac is based on XFEL/ILC superconducting technology, but CW regime of operation requires the modification of components to satisfy LCLS-II requirements. TTF-III coupler is considered as a candidate for a fundamental power coupler for the 1.3 GHz 9-cell accelerating structure at the LCLS-II project. In this paper we discuss the results of multiphysics analysis of the coupler working at various operating regimes. Two major modifications are proposed in order to meet the LCLS-II requirements and eliminate possible overheating: reducing the length of antenna (cold part) and increasing the thickness of a cooper plating on the inner conductor of the warm part of the coupler.

MOPP060	Status of the GSI Poststripper - HE-Linac	DTL, rfq, linac, ion	190
	S. Mickat, W.A. Barth, G. Clemente, X. Du, L. Groening, A. Orzhekhovskaya, B. Schlitt, H. Vormann, C. Xiao, S.G. Yaramyshev GSI, Darmstadt, Germany M. Droba, H. Hähnel, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	The High-Energy (HE) Linac is proposed to substitute the existing UNILAC post-stripper section. The post-stripper is an Alvarez DTL, which is in operation over four decades successfully. A quasi Front-to-End simulation along the UNILAC shows, that by taking future upgrade options into account already, with the existing Alvarez section the Fair requirements are not reached. Even by substituting the Alvarez section by the HE Linac the aim is not reached per se regarding the existing boundary conditions. Currently workpackages are defined together with the Institute of Applied Physics at Frankfurt University. Starting from the Ion sources to the SIS18 transfer channel every section is reinvestigated for improvements in beam quality and intensity.

MOPP061	First RF Measurements of the Superconducting 217 MHz CH Cavity for the CW Demonstrator at GSI	cavity, 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, rfq, emittance, cavity	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]

MOPP065	Investigations of Space-Charge Compensation in Low-Energy Beam Transport (LEBT) Sections Using a Particle-in-Cell Code	electron, ion, proton, space-charge	205
	D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner IAP, Frankfurt am Main, Germany
	Among the advantages of magnetostatic LEBT sections is the possibility for compensation of space charge by electrons in the case of positively charged ion beams. In the past, it has been shown that the distribution of these compensation electrons can lead to unwanted emittance growth. However, the distribution of electrons especially in the presence of the magnetic fields of the focussing lenses is difficult to predict. To improve the understanding of the influence on the beam, models for the relevant processes namely residual gas ionization using realistic cross sections as well as secondary electron production on surfaces have been implemented in a particle-in-cell code. In this contribution, we will present the code used as well as first results for two model systems as an example.

MOPP068	The Fast Piezo-Based Frequency Tuner for SC CH-Cavities	cavity, resonance, laser, 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]

MOPP084	Nondestructive Diagnostics of Proton Beam Halo and Transverse Bunch Position by Cerenkov Slow Wave Structures	proton, diagnostics, monitoring, electron	251
	S.V. Kuzikov, M.B. Goykhman, A.V. Gromov, A.V. Palitsin, Yu.V. Rodin, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	An appearance of the halo around bunch of particles is very undesirable destructive phenomenon in high-intensity proton accelerators. We suggest using built-in short BWO section in form of the corrugated metallic waveguide, in order to control particle distribution in real time. In BWO low velocity proton bunch has synchronism with slow spatial harmonic of TM01 wave. Fields of slow harmonic sharply grow in direction from axis to walls and rf power, generated by flying bunch of the given charge, critically depends on transverse bunch size. Results of the simulation, carried out for 20 pC proton bunch of 10 ps duration, show that in 5 GHz BWO of 30 cm length the output rf pulse of several nanosecond duration is varied from mW- level (for 1 mm transverse bunch size) to several tens of mW (for bunch of 20 mm radius). This power level is high enough to control halo appearance in each single proton bunch. The producible rf power in a BWO is also dependent on bunch deflection from axis. This effect we plan to use, in order to provide transverse bunch position monitoring by means of two additional rectangular slow wave section which have corrugations on mutually perpendicular walls.
	Poster MOPP084 [0.732 MB]

MOPP087	Construction of the Modules of the IFMIF-EVEDA RFQ	rfq, status, controls, survey	257
	A. Pepato, E. Fagotti, F. Grespan, A. Palmieri, A. Pisent, C. R. Roncolato INFN/LNL, Legnaro (PD), Italy R. Dima, L. Ferrari, E. Udup INFN- Sez. di Padova, Padova, Italy A. Margotti INFN-Bologna, Bologna, Italy P. Mereu INFN-Torino, Torino, Italy
	The IFMIF project aims to produce an intense neutron flux to test and qualify materials suitable for the construction of fusion power plants. We are working on the engineering validation phase of the project, which consists on the construction of a linear accelerator prototype to be installed and commissioned in Rokkasho. The RFQ is composed of 18 modules flanged together for a total length of 9.8m designed to accelerate the 125mA D⁺ beam to 5MeV at a frequency of 175MHz. The mechanical specifications are very challenging, tight tolerances are required on the machining and on the brazing process. The line is subdivided into 3 Super Modules of 6 modules each. The production of the High Energy portion has been completed and delivered, while the Low Energy one is performing the acceptance test. They were commissioned to external firms. The production of the Intermediate Energy portion has been done in house (INFN) and will be commissioned soon. The 1st modules (16, 17 and 2) were produced adopting 2 brazing steps, while for all the remaining ones we adopted a single brazing step. In this paper the production status and the development of the brazing procedure will be described.

MOPP090	Adjustment of the Coupling Factor of the Input Coupler of the ACS Linac by a Capacitive Iris in J-PARC	cavity, coupling, 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.

MOPP091	Beam Test of a New RFQ for the J-PARC Linac	rfq, linac, emittance, experiment	267
	Y. Kondo, T. Morishita, Y. Sawabe, S. Yamazaki JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Hori JAEA, Ibaraki-ken, Japan A. Takagi KEK, Ibaraki, Japan
	We performed a beam test of a new 324-MHz 3-MeV RFQ (RFQ III) for the beam-current upgrade of the J-PARC linac. RFQ III is the first RFQ developed to meet the requirement of the J-PARC linac. The peak beam current is 50mA, pulse length is 500 micro-sec, and the repetition is 25 Hz. Before the installation to the accelerator tunnel scheduled in summer of 2014, we built a test stand for offline testing of the new ion source and RFQ. Basic performances of RFQ III such as transmission, transverse emittance, and energy spread were measured with short pulse length beams. In this paper, we present the results of the beam test.

MOPP103	Fault Tolerance and Consequences in the MYRRHA Superconducting Linac	linac, cavity, operation, cryomodule	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.

MOPP106	3D Mode Analysis of Full Tanks in Drift-Tube Linacs	DTL, linac, emittance, drift-tube-linac	300
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio. [1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951.

MOPP110	Multipacting Prediction for the 10⁶.1 MHz Quarter Wave Resonator	cavity, 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.

MOPP130	A Linac-Based Approach to Modelling an Orbit Separated Cyclotron	cavity, linac, cyclotron, 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	cavity, electron, gun, cathode	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, cavity, 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	cavity, proton, 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.

MOPP135	Exact Solutions of the Vlasov Equation in Magnetic Field	distributed, software	377
	O.I. Drivotin, D.A. Ovsyannikov St. Petersburg State University, St. Petersburg, Russia
	Funding: This work was supported by St.-Petersburg State University grant #9.38.673.2013. This report is devoted to self-consistent distributions for charged particle beam which are regarded as solutions of the Vlasov equation. New approach based on covariant formulation of the Vlasov equation* is developed. Such approach allows using various coordinates in the phase space. It is shown how to apply this approach to the problem of finding of solutions of the Vlasov equation for charged particle beam. Solutions obtained within the framework of this approach are presented. Most known example is the Kapchinsky-Vladimirsky distribution. Wide classes of distributions for uniformly charged beam are also considered. * O.I. Drivotin. Covariant formulation of the Vlasov equation. Proc. of 2011 Int. Part. Acc. Conf.(IPAC'2011), San-Sebastian, Spain, 2011. accelconf.web.cern.ch/accelconf/ipac2011/papers/wepc114.pdf

MOPP138	Fabrication and Measurements of 500 MHz Double Spoke Cavity	cavity, electron, 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]

MOPP139	Studies of Coherent Synchrotron Radiation in the Jefferson Lab FEL Driver with Implications for Bunch Compression	linac, emittance, acceleration, FEL	388
	C. Tennant, D. Douglas, R. Li JLab, Newport News, Virginia, USA C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
	Funding: Work supported by the Office of Naval Research and the High Energy Laser Joint Technology. Jefferson Laboratory work is supported under U.S. DOE Contract No. DE-AC05-06OR23177. The Jefferson Laboratory IR FEL Driver provides an ideal test bed for studying a variety of beam dynamical effects. Recent studies focused on characterizing the impact of coherent synchrotron radiation (CSR) with the goal of benchmarking measurements with simulation. Following measurements to characterize the beam, we quantitatively characterized energy extraction via CSR by measuring beam position at a dispersed location as a function of bunch compression. In addition to operating with the beam on the rising part of the linac RF waveform, measurements were also made while accelerating on the falling part. For each, the full compression point was moved along the backleg of the machine and the response of the beam (distribution, extracted energy) measured. Initial results of start-to-end simulations using a 1D CSR algorithm show remarkably good agreement with measurements. A subsequent experiment established lasing with the beam accelerated on the falling side of the RF waveform in conjunction with positive momentum compaction (R56) to compress the bunch. The success of this experiment motivated the design of a modified CEBAF-style arc with control of CSR and microbunching effects.

MOPP140	Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector	emittance, coupling, electron, gun	391
	A.D. Cahill, A. Fukasawa, J.B. Rosenzweig UCLA, Los Angeles, California, USA L. Faillace RadiaBeam, Marina del Rey, California, USA B. Spataro INFN/LNF, Frascati (Roma), Italy A. Valloni CERN, Geneva, Switzerland
	A new S-Band photoinjector is being developed at UCLA that will feature a large accelerating gradient at 160 MeV/m creating a beam with approximately 6.5 MeV at the exit. Because of the large accelerating gradient and other considerations, such as cooling and manufacturing, the new Supergun will be coupled into using a coaxial method, rather than side coupling. With the large accelerating gradient we hope to create very low emittance beams on the order of 0.025 mm mrad. These beams can then be used for a number of purposes, mainly for high quality beams used in FELs. Electric simulations have been done using HFSS and Superfish. Heating and mechanical simulations were done using Ansys. Finally, beam simulations were completed with GPT.

TUPP004	An In-flight Radioactive Ion Separator Design for the ATLAS Facility	dipole, ion, quadrupole, target	446
	B. Mustapha, B. Back, C.R. Hoffman, B.P. Kay, 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. An in-flight radioactive beam separator, named AIRIS, is being designed to enhance the radioactive beam capabilities of the ATLAS facility at Argonne. In order to serve all the experimental areas while maintaining the stable beam capabilities, the separator design is of broadband type. This design allows the selected radioactive beam to come back on the ATLAS beam line while stable beams continue on the same straight line with the separator turned off. The separation is performed in two steps, the first is magnetic in a chicane made of four magnets and four multipoles, while the second uses an rf sweeper taking advantage of the time separation between the beam of interest and potential contaminants including the primary beam tail. We will report on the progress of the AIRIS design effort with special emphasis on the performance of the rf sweeper.

TUPP006	Design of Relativistic Magnetron for High Power Microwave Generation	electron, extraction, cathode, cavity	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	cavity, 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]

TUPP020	Beam Dynamics Simulation for FLASH2 HGHG Option	FEL, undulator, radiation, electron	471
	G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov DESY, Hamburg, Germany K.E. Hacker DELTA, Dortmund, Germany T. Plath Uni HH, Hamburg, Germany
	The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP022	RF Tuning of a S-band Hybrid Buncher for Injector Upgrade of LINAC II at DESY	linac, electron, target, experiment	478
	Y.C. Nie, M. Hüning, C. Liebig, M. Schmitz DESY, Hamburg, Germany
	LINACII at DESY currently provides 450 MeV electrons for the synchrotron radiation source PETRAIII. The injector upgrade of it aims to improve its reliability and mitigate the radiological activation due to electron losses at hundreds of MeV. Therefore, a 2.998 GHz hybrid buncher has been developed and will be installed in between a pre-buncher and LINAC II. It comprises a 1-cell standing-wave (SW) section for rapid acceleration and a 13-cells travelling-wave (TW) section for further bunching and acceleration. This paper focuses on its rf tuning procedure. The tuning strategy combines a non-resonant bead-pull measurement of complex electric field and a linear model for local reflection coefficient calculation. The tuning result is satisfying. Field unflatness of the TW section has been improved from ±9% to ±4%, and field in the SW section has been enhanced significantly. By using ASTRA simulation, it has been verified that the residual detuning of the structure is acceptable in view of beam dynamics performance.

TUPP030	Design of a High Average Current Electron Source for the CLIC Drive Beam Injector	gun, cathode, emittance, electron	493
	S. Döbert, N. Chritin CERN, Geneva, Switzerland B. Cadilhon, B. Cassany, J. Gardelle, K. Pepitone CEA, LE BARP cedex, France
	The drive beam injector for CLIC needs to deliver a 4.2 A electron beam for a duration of 140 μs with a repetition rate of 50 Hz. The shot to shot and flat top current stability has to be better than 0.1% to guarantee the beam stability required for CLIC. Based on the experience with the CTF3 injector a thermionic high voltage gun with a gridded cathode has been designed together with a sub-harmonic bunching system to achieve these requirements. The grid will allow controlling the current and eventually feedback on the flattop shape. The gun will operate at 140 kV and an emittance of 14 mm mrad can be obtained. The paper describes the design approach and the results of the systematic electromagnetic simulations to optimize the gun. Care was taken during the mechanical design of the gun to obtain a modular design allowing adjusting for different beam currents and cathode sizes.

TUPP036	Space Charge Compensation in the Linac4 LEBT for Three Injected Gas Types	emittance, ion, linac, space-charge	510
	C.A. Valerio, R. Scrivens CERN, Geneva, Switzerland N. Chauvin CEA/IRFU, Gif-sur-Yvette, France
	The space charge of unbunched, high intensity beams can be compensated by the trapping of charged particles in the potential well of the beam. The source of these secondary charge particles can be the residual gas in the beam line. The effect is important in the Low energy beam transport (LEBT) regions. At CERN’s Linac4, the LEBT transports a pulsed 45keV H⁻ beam, which is compensated by the positive ions, created by collision of the beam with the neutral gas in the beam pipe. The rise time and amount of compensation may be varied by the density of neutral gas and the type of gas used (through the cross-section for ion production and the mass of the resulting ion). In this paper we present measurement results for the transport of the beam at the Linac4 LEBT with the addition of hydrogen, nitrogen and krypton gases into the line, and compare them with simulations of the beam dynamics including the effect of compensating positive ions . The H⁻ beam is provided by a cesiated 2MHz RF ion source with an external solenoidal antenna, operating with 600us pulses at 0.8Hz repetition rate.
	Slides TUPP036 [4.084 MB]
	Poster TUPP036 [1.356 MB]

TUPP038	Transverse Beam Profile Measurements in the Linac4 Medium Energy Beam Transport	emittance, linac, quadrupole, rfq	516
	M. Yarmohammadi Satri, G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca CERN, Geneva, Switzerland
	Linac4 is a 160 MeV H⁻ linear accelerator presently under construction at CERN. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The Linac4 front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) which accelerates the beam to 3 MeV and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been commissioned in the Linac4 tunnel. The MEBT is composed of three buncher cavities and 11 quadrupole magnets to match the beam from the RFQ to the next accelerating structure (DTL) and it includes two wire scanners for beam profile measurement. In this paper we present the results of the profile measurements and we compare them with emittance measurements taken with a temporary slit-and-grid emittance measurement device located after the MEBT line.

TUPP059	Advanced Beam Matching to a High Current RFQ	rfq, quadrupole, emittance, ion	559
	S.G. Yaramyshev, W.A. Barth, L.A. Dahl, P. Gerhard, L. Groening, M.T. Maier, S. Mickat, A. Orzhekhovskaya, B. Schlitt, H. Vormann GSI, Darmstadt, Germany
	The High Current Injector (HSI) of the heavy ion linac UNILAC at GSI comprises the transport lines, the RFQ and two DTL tanks. Beam matching to the RFQ acceptance with a magnetic quadrupole quartet has been worked out manually during commissioning and operation of the machine. Due to a strong overlapping of the field from neighboring quadrupole lenses, a standard optics calculation does not provide for the required reliability. Advanced beam dynamics simulations have been done with the macroparticle code DYNAMION. The superposition of the measured magnetic fields of each quadrupole was taken into account. The quadrupole settings were optimized using the Monte-Carlo method. Two solutions have been found in accordance with the general theory of particle optics. Beam dynamics simulations with new quadrupole settings show an increased particle transmission through the RFQ. The results of numerical study have been confirmed during experimental campaigns. An improved performance of the whole HSI has been demonstrated. The proposed algorithm and a comparison of the measured data with result of simulations are presented.

TUPP060	Development of a 217 MHz Superconducting CH Structure	cavity, 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, cavity	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]

TUPP065	RF Input Power Couplers for High Current SRF Applications	cavity, booster, SRF, linac	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]

TUPP085	RAON Cryomodule Design for QWR, HWR, SSR1 and SSR2	cryomodule, linac, vacuum, cavity	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.

TUPP089	Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac	DTL, linac, cavity, 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	cavity, coupling, vacuum, rfq	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.

TUPP097	100-MeV Proton Beam Phase Measurement by Using Stripline BPM	linac, proton, DTL, coupling	656
	H.S. Kim, Y.-S. Cho, H.-J. Kwon KAERI, Daejon, Republic of Korea
	Funding: This work is supported by Ministry of Science, ICT & Future Planning of the Korean Government. In Korea Multipurpose Accelerator Complex (KOMAC), a 100-MeV proton linac, which is composed of a proton injector based on the microwave ion source, 3-MeV RFQ with a four-vane type and 100-MeV DTL with electromagnetic quadrupoles has been developed and currently provides the proton beam to users for various applications. To increase the beam power up to the design value, several improvements are required including the fine adjustment of the RF set-point during the operation. A stripline BPM is used for the beam phase measurement, where the pickup signals from four electrodes are combined by using the RF combiner, then mixed with 300 MHz LO reference signal resulting in 50 MHz IF signal which is processed by digital IQ demodulation method. In this paper, the details of the beam phase measurement setup and results will be presented.

TUPP103	The Beam Envelope Control in SC Linac for the Proton Radiotherapy	linac, controls, proton, cavity	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	cavity, gun, 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.

TUPP113	High RF Power Test of Coupled RFQ-SFRFQ Cavity	cavity, rfq, 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]

TUPP127	R&D of X-band Accelerating Structure for Compact XFEL at SINAP	FEL, linac, wakefield, radiation	715
	W. Fang, Q. Gu, M. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China A.A. Aksoy, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey D. Angal-Kalinin, J.A. Clarke Cockcroft Institute, Warrington, Cheshire, United Kingdom C.J. Bocchetta, A.I. Wawrzyniak Solaris, Kraków, Poland M.J. Boland SLSA, Clayton, Australia G. D'Auria, S. Di Mitri, C. Serpico Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy T.J.C. Ekelöf, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden E.N. Gazis National Technical University of Athens, Athens, Greece A. Grudiev, A. Latina, D. Schulte, S. Stapnes, W. Wuensch CERN, Geneva, Switzerland
	One compact hard X-ray FEL facility is being planned at SINAP, and X-band high gradient accelerating structure is the most competetive scheme for this plan. X-band accelerating structure is designed to switch between 60MV/m and 80MV/m, and carries out 6GeV and 8GeV by 130 meters linac respectively. In this paper, brief layout of compact XFEL will be introduced, and in particular the prototype design of dedicated X-band acceleration RF system is also presented.

TUPP128	ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam	laser, radiation, electron, FEL	719
	D. Huang, Q. Gu, Z. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

TUPP130	Optimization of Beam Parameters in APF Channel	linac, controls, emittance, rfq	722
	V.V. Altsybeyev, D.A. Ovsyannikov St. Petersburg State University, St. Petersburg, Russia
	A new approach based on mathematical optimization methods to obtain a synchronous phase sequence in APF linacs is suggested. The optimization problem of intensity deuteron beam parameters is discussed. As an example, the results of beam dynamics simulations are presented.

THPP012	A Prototype 1 Mev X-Band Linac for Aviation Cargo Inspection	cavity, linac, electron, 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	cavity, dipole, damping, 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.

THPP014	Catalogue of Losses for the Linear IFMIF Prototype Accelerator	rfq, beam-losses, operation, distributed	860
	N. Chauvin, P.A.P. Nghiem, D. Uriot CEA/IRFU, Gif-sur-Yvette, France M. Comunian INFN/LNL, Legnaro (PD), Italy C. Oliver CIEMAT, Madrid, Spain
	One of the activities of the EVEDA (Engineering Validation and Engineering Design Activities) phase of the IFMIF (International Fusion Materials Irradiation Facility) project consists in building, testing and operating, in Japan, a 125 mA/9 MeV deuteron accelerator, called LIPAc, which has been developed in Europe. For the accelerator safety aspects, a precise knowledge of beam loss location and power deposition is crucial, especially for a high intensity, high power accelerator like LIPAc. This paper presents the beam dynamics simulations allowing to estimate beam losses in different situations of the accelerator lifetime: starting from scratch, beam commissioning, tuning or exploration, routine operation, sudden failure. Some results of these studies are given and commented. Recommendations for hot point protection, beam stop velocity, beam power limitation are given accordingly.
	Slides THPP014 [4.780 MB]

THPP025	RF Design and Low Power Measurements of a Nose-Cone Single Gap Buncher Cavity	cavity, pick-up, coupling, factory	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.

THPP028	Design and Beamloading-Simulations of a Pre-Bunching Cavity for the CLIC Drive Beam Injector	cavity, beam-loading, 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	cavity, 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]

THPP033	Linac4 Transverse and Longitudinal Emittance Reconstruction in the Presence of Space Charge	emittance, linac, quadrupole, rfq	913
	J.-B. Lallement, G. Bellodi, V.A. Dimov, A.M. Lombardi, M. Yarmohammadi Satri CERN, Geneva, Switzerland M. Yarmohammadi Satri IPM, Tehran, Iran
	Linac4 is a pulsed, normal-conducting 160 Mev H⁻ linear accelerator presently under construction at CERN. It will replace the present 50 MeV Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The 3 MeV front end, composed of a 45 keV ion source, a Low Energy Beam transport (LEBT), a 352 MHz Radio Frequency Quadrupole (RFQ) at 3 MeV and Medium Energy Beam Transport (MEBT) housing a beam chopper, and the first Drift Tube Linac (DTL) tank at 12 MeV have been commissioned during the first half of 2014. The transverse and longitudinal emittance reconstruction technique in the presence of space charge, that will be used for the next commissioning stages and permanently during the Linac operation, was successfully tested and validated. The reconstruction method and the results obtained at 3 and 12 MeV are presented in this paper.

THPP043	Benchmark of the Beam Dynamics Code DYNAC Using the ESS Proton Linac	linac, rfq, space-charge, DTL	945
	E. Tanke, R. De Prisco, M. Eshraqi, R. Miyamoto, A. Ponton, E. Sargsyan ESS, Lund, Sweden S. Valero CEA, Gif-sur-Yvette, France
	The beam dynamics code DYNAC is benchmarked using the ESS Proton Linac. Recent work on improvements in the code, including of the RFQ model, is discussed. The three space charge routines contained in DYNAC, including a 3D version, have remained unchanged. The code contains a numerical method, capable of simulating a multi-charge state ion beam in accelerating elements. In addition, protons, single charge state heavy ions and non-relativistic electrons in accelerating elements can be modeled using an analytical method. The benchmark will include comparisons of both methods with the beam dynamics models in use at ESS: TraceWin and Toutatis. As this analytical method used in DYNAC is fast, it is a prime candidate for use as an online beam simulation tool.

THPP048	Design of a Compact Lever Slow/Fast Tuner for 650 MHz Cavities for Project X	cavity, operation, resonance, 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, cavity, 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.

THPP055	High Power Density Test of PXIE MEBT Absorber Prototype	radiation, electron, experiment, focusing	973
	A.V. Shemyakin, C.M. Baffes Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. Two prototypes of the absorber were manufactured from molybdenum alloy TZM, and tested with a 28 keV DC electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototypes and key testing results.

THPP060	Effect of Cavity Couplers Field on the Beam Dynamics of the LCLS-II Injector	HOM, cavity, 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.

THPP069	Status and Outlook of the 325 MHz 4-Rod RFQ	rfq, dipole, HOM, impedance	1010
	B. Koubek, H. Podlech, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany
	In order to built a Radio Frequency Quadrupole (RFQ) at 325 MHz for the FAIR proton linac, a 4-rod structure has been investigated. The RF design, especially the dipole and fringe fields and higher order modes, has been studied with simulations. A prototype has been built and power tested to verify the simulation results and investigate the high power performance. This paper summarizes the results of the research concerning the 325 MHz 4-rod RFQ and gives an overview about the next steps in this project.

THPP071	Proposal of a 325 MHz Ladder-RFQ for the FAIR Proton-Linac	rfq, proton, dipole, quadrupole	1016
	M. Schütt, U. Ratzinger IAP, Frankfurt am Main, Germany R. M. Brodhage GSI, Darmstadt, Germany
	Funding: BMBF 05P12RFRB9 For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The first rf accelerator element is a 325 MHz RFQ accelerating from 95 keV to 3.0 MeV. RFQ’s beyond 300 MHz were realized in 4-Vane-type geometry so far. At IAP there is a tradition in 4-Rod-type RFQ development. This type of RFQ is dominating at lower frequencies. Very promising results have been reached with a ladder type-RFQ, which has been investigated during 2013. In comparison with a traditional 4-Rod RFQ approach the geometry is more convenient at high frequencies. We will show most recent 3D simulations of the frequency tuning possibilities and of a whole cavity demonstrating the power of a ladder type RFQ. An RFQ layout for the new FAIR proton injector will be shown. (see also R. Brodhage, U. Ratzinger, A. Almomani, “Design Study of a High Frequency Proton Ladder RFQ” , Proc. of the 2013 IPAC Conference, Shanghai, China, p. 3788.)

THPP075	Development of Superconducting Spoke Cavity for Electron Accelerators	cavity, 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	cavity, operation, 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.

THPP079	Prototyping Progress of SSR1 Single Spoke Resonator for RAON	cavity, target, 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.

THPP084	Cyclotron-Undulator Cooling of Electron Beams	undulator, electron, cyclotron, FEL	1041
	S.V. Kuzikov, I.V. Bandurkin, A.V. Savilov IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	XFELs require high-quality electron beams which can be produced in damping rings. For XFEL, based on Compton scattering of laser light, instead of the damping ring we consider a new compact device where electrons move in the undulator with axial DC magnetic field. In this undulator electrons move near resonant condition, rotating with cyclotron frequency and wiggling at similar bounce frequency. Such undulator allows compensation of the initial velocity spread by perturbations of the longitudinal velocities caused by transverse wiggling. Calculation show that ~1% velocity spread of 5 MeV electron beam (typical for photoinjectors) can be reduced to ~0.01% at distance as long as 20 undulator periods. In the advanced scheme, where the described undulators alternate with sections of the cyclotron radiation, energy spread as small as 0.001% is reachable. Calculations show that this principle works also for high energy beams (100 MeV and more), where RF undulator instead of DC-magnet undulator is preferable.
	Poster THPP084 [0.713 MB]

THPP085	The Prototype of the Proton Injector for the European Spallation Source	plasma, proton, extraction, emittance	1044
	L. Celona, L. Andò, G. Castro, S. Gammino, D. Mascali, L. Neri, G. Torrisi INFN/LNS, Catania, Italy
	The update of the design of the PS-ESS source and of its LEBT has been carried out in 2013 and the construction is now ongoing. The Ion Source will be able to provide a proton beam current larger than 70 mA to the 3.6 MeV RFQ. Several innovative solutions have been implemented in the redesign phase in order to cope with high-reliability/high-performance requirements of the ESS project. A flexible magnetic system will allow to investigate alternative configurations for future ion current upgrade of the machine based on the formation of a denser plasma. Innovative set-ups have been also explored for beam extraction, transport and chopping. Calculations have shown that space charge compensation up to 95 % is needed to preserve the low emittance in the low energy beam transfer line (LEBT). In order to obtain the optimal proton beam pulse rise and fall time – that should be 100 ns – we propose a LEBT chopping configuration that permits hundred nanosecond rise times despite the LEBT compensation needs few microseconds. The ongoing development of a 3D PIC code will be also described, that should allow predicting and tuning the beam pulse for different source/LEBT operative configurations.

THPP090	Longitudinal Measurement of Annular-Ring Coupled Structure Linac in J-PARC	injection, linac, distributed, rfq	1056
	T. Maruta, Y. Liu KEK/JAEA, Ibaraki-Ken, Japan A. Miura JAEA/J-PARC, Tokai-mura, Japan
	In the J-PARC linac, Annular-type Coupled Structure (ACS) linac was introduced for the beam energy extension to 400 MeV in year 2013. To measure the longitudinal property of the ACS, we measured acceptance in phase direction by synchronous phase scan method and confirm that the acceptance is consistent with that by 3D PIC simulation. Simultaneously, the output beam energy from ACS was measured by orbit displacement where the dispersion is large. In this presentation, we discuss the measurement method and results.

THPP095	Design Study of Superconducting Linear Accelerator for Unstable Ion Beams in RISP	linac, emittance, ion, ISOL	1071
	J.G. Hwang, C. Kim, E.-S. Kim Kyungpook National University, Daegu, Republic of Korea B.H. Choi, H. Jang, D. Jeon, H.J. Kim, H.J. Kim, I. Shin IBS, Daejeon, Republic of Korea L. Lee KNU, Deagu, Republic of Korea
	The post accelerator of RAON can accelerate the unstable and stable ion beams up to 15 MeV/u for 132Sn¹⁶⁺ and 58Ni⁸⁺ for 16.5 MeV/u, which has the ratio of mass to charge, A/q, of 8.3. The unstable ion beam such as 132Sn¹⁶⁺ produced by an ISOL system has the large transverse and longitudinal emittances. The post-accelerator consists of post-LEBT, RFQ, MEBT and superconduction linac(SCL3 and we optimized acceptance and beam envelope based on the beam dynamics in the linac. The accelerated beam by post accelerator was transported by the post-to-driver transport (P2DT) line which consists of a charge stripper, two charge selection sections and a telescope section with the bunching cavities to the high energy linac(SCL2) and accelerated up to 200 MeV/u. In this presentation, we will show the criteria for the design of the post accelerator and result of beam tracking simulation from post-LEBT to end of high energy linac.

THPP097	3D Effects in RFQ Accelerators	rfq, quadrupole, cavity, 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.

THPP104	Simulation of the Electron Beam Dynamics in the Biperiodical Structure	electron, coupling, Windows, impedance	1096
	Yu.D. Kliuchevskaia, T.V. Bondarenko, S.M. Polozov MEPhI, Moscow, Russia
	А biperiodical accelerating structure (BAS) with operating frequency 27 GHz for the 6 MeV compact radiotherapy electron accelerator is considered. The operating frequency 27 GHz allows to significantly reduce the facility sizes, unlike the S-, X- and C-band operating linacs. The optimal geometrical parameters of BAS necessary for π/2 mode were defined by means of accelerating and coupling cell tuning. The BAS coupler was also simulated. Results of the electron beam dynamics analysis in designed structure are also discussed.

THPP105	Beam Dynamics Simulation for the 1 GeV High Power Proton Linac	linac, focusing, rfq, proton	1099
	S.M. Polozov, V.S. Dyubkov, T. Kulevoy, A.V. Samoshin MEPhI, Moscow, Russia G. Kropachev, T. Kulevoy ITEP, Moscow, Russia
	Funding: This work is supported in part by the Ministry of Science and Education of Russian Federation under contract No. 14.516.11.0084 The design of high energy and high power proton linacs for accelerating driven systems (ADS) is one of the accelerator technology frontiers. Such linacs are under developing in EU, Japan, PRC but not discussed in Russia previous fifteen years. The driver linac and the breeder conceptual designs were funded by the Ministry of Science and Education of Russian Federation in 2013. The 2 MeV RFQ linac was proposed as the first accelerating section. A number of RF focusing sections types (by RF crossed lenses, modified electrode profile RFQ, axi-symmetrical RF focusing) were discussed for medium energies. The conventional modular scheme linac based on spoke-cavities and 5-cell elliptical cavities was designed for higher energies. The results of beam dynamics simulation in this linac will present.

THPP112	Multipacting Optimization of a 750 MHz RF Dipole	dipole, cavity, 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.

THPP120	Status of Radio-Frequency (RF) Deflectors at Radiabeam	electron, cavity, 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.

THPP126	Design of the High Repetition Rate Photocathode Gun for the CLARA Project	cavity, gun, 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.

THPP129	Carbon Field Emission Strip Cathode Electron Source	electron, cathode, vacuum, focusing	1
	T.V. Bondarenko, A.I. Botyachkova, G.G. Karpinskiy, S.A. Polikhov, G.B. Sharkov Siemens Research Center, Moscow,, Russia A.I. Botyachkova, G.G. Karpinskiy National Research Nuclear University (MEPhI), Moscow, Russia A.E. Geisler, O. Heid Siemens AG, Erlangen, Germany
	Over the recent years carbon nanostructure cathodes have become promising as a high brightness electron sources with large working area for field emission structures. Measurements and calculations of a field emission strip cathode based on carbon structure and a unit for its investigation are presented in the article. For measuring of the cathode emitting properties and determination of the electrons initial parameters used in the electron beam computer simulation the experimental setup is been developed. The setup consists of the high-voltage triode electrode system and allows to investigate the voltage-current characteristics of the cathode and to estimate the electron distribution of the beam on the anode surface. The anode electron distribution evaluations are processed by the measurements of the emitted X-ray focal spot on the anode by application of the CCD camera. Verification of the simulated electron beam dynamics can be obtained by application of the experimentally acquired data.
	Poster THPP129 [4.088 MB]

THPP138	Measurements of Beam Current and Energy-Dispersion for Ion Beam with Multi-Components	ion, ion-source, vacuum, experiment	1185
	A.L. Zhang University of Chinese Academy of Sciences, Beijing, People's Republic of China J.E. Chen, Z.Y. Guo, S.X. Peng, H.T. Ren, Y. Xu, T. Zhang, J. Zhao PKU, Beijing, People's Republic of China J.E. Chen Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
	Funding: This work is supported by the National Science Foundation of China（Grant Nos. 91126004). The multi-component ion beam is very common in nuclear physics, materials physics and most kind of ion source. But the diagnosis of multi-component ion beam [1] can be difficult because of its complex composition and irregular energy-dispersion. We need an effective way to analyzing the multi-component ion beam. There is a multi-component ion beam whose total beam current varies from 1 mA to 50mA and the beam energy can be 20keV to 150keV. In this paper, four methods to analyzing this multi-component ion beam are described, which are Faraday cup array method, fluorescent screen with Faraday cup, movable aperture with conductive fluorescent screen, and current calibration method, respectively. The distributions and currents of the separated ion beams are obtained by means of the four methods, and the current and energy-dispersion of each component might be measured at the same time. This is of special interest for beams with multi-components. Detailed description and comparison of the four methods are discussed in this paper. Correspondence Author:Peng ShiXiang. Email: sxpeng@pku.edu.cn
	Poster THPP138 [0.419 MB]

FRIOB01	Positive Trends in Radiation Risk Assessment and Consequent Opportunities for Linac Applications	radiation, linac, FEL, controls	1202
	Y. Socol Falcon Analytics, Netanya, Israel
	Ionizing radiation, an unavoidable by-product of high-energy LINACs, makes them subject to strict regulation and severe public concerns. During the last two decades the attitude to ionizing radiation hazards has been becoming more balanced, as opposed to the historical "radiophobia". The linear no-threshold hypothesis (LNTH), based on the assumption that every radiation dose increment constitutes increased cancer risk for humans, is more and more debated. In particular, the recent memorandum of the International Commission on Radiological Protection admits that the LNTH predictions at low doses are "speculative, unproven, undetectable and "phantom'." Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of ionizing radiation may be beneficial to human health. While these advances in scientific understanding have not yet given fruit regarding radiation regulation and policy, we are hopeful these may happen in near to middle term. The presentation reviews the present status of the low-dose radiation-hazard debate. It also outlines anticipated opportunities for LINAC applications, especially in the prospective field of low-dose radiation therapy.
	Slides FRIOB01 [1.890 MB]

Paper

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MOIOC03

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

cavity, linac, 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]

MOPP028

New Criterion for Shape Optimization of Normal-Conducting Accelerator Cells for High-Gradient Applications

factory, database, resonance, impedance

114

K.N. Sjobak, A. Grudiev
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway

When optimizing the shape of high-gradient accelerating cells, the goal has traditionally been to minimize the peak surface electric field / gradient, or more recently minimizing the peak modified Poynting vector / gradient squared. This paper presents a method for directly comparing these quan- tities, as well as the power flow per circumference / gradient squared. The method works by comparing the maximum tolerable gradient at a fixed pulse length and breakdown rate that can be expected from the different constraints. The paper also presents a set of 120° phase-advance cells for traveling wave structures, which were designed for the new CLIC main linac accelerating structure, and which are optimized according to these criteria.

MOPP032

Experimental Verification Towards Feed-Forward Ground Motion Mitigation at ATF2

ground-motion, quadrupole, feedback, controls

124

J. Pfingstner, K. Artoos, C. Charrondière, S.M. Janssens, M. Patecki, Y. Renier, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
A. Jeremie
IN2P3-LAPP, Annecy-le-Vieux, France
K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

Without counter measures, ground motion effects would deteriorate the performance of future linear colliders to an unacceptable level. An envisioned new ground motion mitigation method (based on feed-forward control) has the potential to improve the performance and to reduce the system cost compared to other proposed methods. For the experimental verification of this feed-forward scheme, a dedicated measurement setup has been installed at ATF2 at KEK. In this paper, the progress on this experimental verification is described. An important part of the feed-forward scheme could be already demonstrated, namely the prediction of the orbit jitter due to ground motion measurements.

MOPP035

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

cavity, electromagnetic-fields, coupling, 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, linac, cavity, 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.

MOPP038

Longitudinal Bunch Profile Monitoring at the ESS Linac

linac, proton, neutron, target

143

I. Dolenc Kittelmann, B. Cheymol
ESS, Lund, Sweden

The European Spallation Source (ESS), which is currently under construction, will be a neutron source based on 5MW, 2GeV proton linac. This high intensity linac will among other beam instrumentation require longitudinal bunch profile monitors. These shall be used during the commissioning phase and start-up periods for beam dynamics optimization and beam loss reduction. The paper focuses on the preliminary studies concerning the longitudinal bunch profile monitoring at the ESS linac.

MOPP039

Dynamics of Bunches Partially Chopped with the MEBT Chopper in the ESS Linac

linac, DTL, lattice, quadrupole

146

R. Miyamoto, B. Cheymol, R. De Prisco, M. Eshraqi, A. Ponton, E. Sargsyan
ESS, Lund, Sweden
I. Bustinduy
ESS Bilbao, Bilbao, Spain

The front-end of a hadron linac typically has a transient time during turning on and off and bunches in the head and tail of a pulse from this period likely have wrong parameters and a risk to cause beam losses. A risk of losses must be avoided as possible in a high power machine so these bunches are removed with deflectors called choppers in the ESS Linac. From experiences of other machines, a rise time of a chopper as fast as one RF period (2.84~ns for ESS) is challenging to achieve and not necessarily needed with no ring to inject like ESS, and hence a 10~ns rise time is planned for a chopper in the medium energy beam transport of ESS. This, however, means that several bunches receive intermediate deflections and may propagate with large trajectory excursions. This paper studies dynamics of such partially chopped bunches in detail to ensure no significant loss is caused by them.

MOPP046

On the Design of Higher Order Mode Antenna for LCLS II

HOM, cavity, coupling, higher-order-mode

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.

MOPP050

Transmission Efficiency Measurement at the FNAL 4-rod RFQ

rfq, solenoid, space-charge, ion

168

J.-P. Carneiro, F.G. Garcia, J.-F. Ostiguy, A. Saini, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
B. Mustapha, P.N. Ostroumov
ANL, Argonne, Illinois, USA

This paper presents measurements of the beam transmission performed on the 4-rods RFQ currently under operation at Fermilab. The beam current has been measured at the RFQ exit as a function of the magnetic field strength in the 2 LEBT solenoids. This measurement is compared with a scan performed on the Fermi Grid with the beam dynamics code TRACK. A particular attention is given to the impact, on the RFQ beam transmission, of the space-charge neutralization in the LEBT and of the field asymmetry on the 4-rods RFQ.

MOPP053

TTF-III Coupler Modification for CW Operation

operation, resonance, coupling, status

174

I.V. Gonin, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

LCLS-II linac is based on XFEL/ILC superconducting technology, but CW regime of operation requires the modification of components to satisfy LCLS-II requirements. TTF-III coupler is considered as a candidate for a fundamental power coupler for the 1.3 GHz 9-cell accelerating structure at the LCLS-II project. In this paper we discuss the results of multiphysics analysis of the coupler working at various operating regimes. Two major modifications are proposed in order to meet the LCLS-II requirements and eliminate possible overheating: reducing the length of antenna (cold part) and increasing the thickness of a cooper plating on the inner conductor of the warm part of the coupler.

MOPP060

Status of the GSI Poststripper - HE-Linac

DTL, rfq, linac, ion

190

S. Mickat, W.A. Barth, G. Clemente, X. Du, L. Groening, A. Orzhekhovskaya, B. Schlitt, H. Vormann, C. Xiao, S.G. Yaramyshev
GSI, Darmstadt, Germany
M. Droba, H. Hähnel, U. Ratzinger, R. Tiede
IAP, Frankfurt am Main, Germany

The High-Energy (HE) Linac is proposed to substitute the existing UNILAC post-stripper section. The post-stripper is an Alvarez DTL, which is in operation over four decades successfully. A quasi Front-to-End simulation along the UNILAC shows, that by taking future upgrade options into account already, with the existing Alvarez section the Fair requirements are not reached. Even by substituting the Alvarez section by the HE Linac the aim is not reached per se regarding the existing boundary conditions. Currently workpackages are defined together with the Institute of Applied Physics at Frankfurt University. Starting from the Ion sources to the SIS18 transfer channel every section is reinvestigated for improvements in beam quality and intensity.

MOPP061

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

cavity, 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, rfq, emittance, cavity

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]

MOPP065

Investigations of Space-Charge Compensation in Low-Energy Beam Transport (LEBT) Sections Using a Particle-in-Cell Code

electron, ion, proton, space-charge

205

D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner
IAP, Frankfurt am Main, Germany

Among the advantages of magnetostatic LEBT sections is the possibility for compensation of space charge by electrons in the case of positively charged ion beams. In the past, it has been shown that the distribution of these compensation electrons can lead to unwanted emittance growth. However, the distribution of electrons especially in the presence of the magnetic fields of the focussing lenses is difficult to predict. To improve the understanding of the influence on the beam, models for the relevant processes namely residual gas ionization using realistic cross sections as well as secondary electron production on surfaces have been implemented in a particle-in-cell code. In this contribution, we will present the code used as well as first results for two model systems as an example.

MOPP068

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

cavity, resonance, laser, 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]

MOPP084

Nondestructive Diagnostics of Proton Beam Halo and Transverse Bunch Position by Cerenkov Slow Wave Structures

proton, diagnostics, monitoring, electron

251

S.V. Kuzikov, M.B. Goykhman, A.V. Gromov, A.V. Palitsin, Yu.V. Rodin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

An appearance of the halo around bunch of particles is very undesirable destructive phenomenon in high-intensity proton accelerators. We suggest using built-in short BWO section in form of the corrugated metallic waveguide, in order to control particle distribution in real time. In BWO low velocity proton bunch has synchronism with slow spatial harmonic of TM01 wave. Fields of slow harmonic sharply grow in direction from axis to walls and rf power, generated by flying bunch of the given charge, critically depends on transverse bunch size. Results of the simulation, carried out for 20 pC proton bunch of 10 ps duration, show that in 5 GHz BWO of 30 cm length the output rf pulse of several nanosecond duration is varied from mW- level (for 1 mm transverse bunch size) to several tens of mW (for bunch of 20 mm radius). This power level is high enough to control halo appearance in each single proton bunch. The producible rf power in a BWO is also dependent on bunch deflection from axis. This effect we plan to use, in order to provide transverse bunch position monitoring by means of two additional rectangular slow wave section which have corrugations on mutually perpendicular walls.

Poster MOPP084 [0.732 MB]

MOPP087

Construction of the Modules of the IFMIF-EVEDA RFQ

rfq, status, controls, survey

257

A. Pepato, E. Fagotti, F. Grespan, A. Palmieri, A. Pisent, C. R. Roncolato
INFN/LNL, Legnaro (PD), Italy
R. Dima, L. Ferrari, E. Udup
INFN- Sez. di Padova, Padova, Italy
A. Margotti
INFN-Bologna, Bologna, Italy
P. Mereu
INFN-Torino, Torino, Italy

The IFMIF project aims to produce an intense neutron flux to test and qualify materials suitable for the construction of fusion power plants. We are working on the engineering validation phase of the project, which consists on the construction of a linear accelerator prototype to be installed and commissioned in Rokkasho. The RFQ is composed of 18 modules flanged together for a total length of 9.8m designed to accelerate the 125mA D⁺ beam to 5MeV at a frequency of 175MHz. The mechanical specifications are very challenging, tight tolerances are required on the machining and on the brazing process. The line is subdivided into 3 Super Modules of 6 modules each. The production of the High Energy portion has been completed and delivered, while the Low Energy one is performing the acceptance test. They were commissioned to external firms. The production of the Intermediate Energy portion has been done in house (INFN) and will be commissioned soon. The 1st modules (16, 17 and 2) were produced adopting 2 brazing steps, while for all the remaining ones we adopted a single brazing step. In this paper the production status and the development of the brazing procedure will be described.

MOPP090

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

cavity, coupling, 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.

MOPP091

Beam Test of a New RFQ for the J-PARC Linac

rfq, linac, emittance, experiment

267

Y. Kondo, T. Morishita, Y. Sawabe, S. Yamazaki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Hori
JAEA, Ibaraki-ken, Japan
A. Takagi
KEK, Ibaraki, Japan

We performed a beam test of a new 324-MHz 3-MeV RFQ (RFQ III) for the beam-current upgrade of the J-PARC linac. RFQ III is the first RFQ developed to meet the requirement of the J-PARC linac. The peak beam current is 50mA, pulse length is 500 micro-sec, and the repetition is 25 Hz. Before the installation to the accelerator tunnel scheduled in summer of 2014, we built a test stand for offline testing of the new ion source and RFQ. Basic performances of RFQ III such as transmission, transverse emittance, and energy spread were measured with short pulse length beams. In this paper, we present the results of the beam test.

MOPP103

Fault Tolerance and Consequences in the MYRRHA Superconducting Linac

linac, cavity, operation, cryomodule

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.

MOPP106

3D Mode Analysis of Full Tanks in Drift-Tube Linacs

DTL, linac, emittance, drift-tube-linac

300

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

Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio.
[1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951.

MOPP110

Multipacting Prediction for the 10⁶.1 MHz Quarter Wave Resonator

cavity, 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.

MOPP130

A Linac-Based Approach to Modelling an Orbit Separated Cyclotron

cavity, linac, cyclotron, 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

cavity, electron, gun, cathode

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, cavity, 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

cavity, proton, 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.

MOPP135

Exact Solutions of the Vlasov Equation in Magnetic Field

distributed, software

377

O.I. Drivotin, D.A. Ovsyannikov
St. Petersburg State University, St. Petersburg, Russia

Funding: This work was supported by St.-Petersburg State University grant #9.38.673.2013.
This report is devoted to self-consistent distributions for charged particle beam which are regarded as solutions of the Vlasov equation. New approach based on covariant formulation of the Vlasov equation* is developed. Such approach allows using various coordinates in the phase space. It is shown how to apply this approach to the problem of finding of solutions of the Vlasov equation for charged particle beam. Solutions obtained within the framework of this approach are presented. Most known example is the Kapchinsky-Vladimirsky distribution. Wide classes of distributions for uniformly charged beam are also considered.
* O.I. Drivotin. Covariant formulation of the Vlasov equation. Proc. of 2011 Int. Part. Acc. Conf.(IPAC'2011), San-Sebastian, Spain, 2011. accelconf.web.cern.ch/accelconf/ipac2011/papers/wepc114.pdf

MOPP138

Fabrication and Measurements of 500 MHz Double Spoke Cavity

cavity, electron, 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]

MOPP139

Studies of Coherent Synchrotron Radiation in the Jefferson Lab FEL Driver with Implications for Bunch Compression

linac, emittance, acceleration, FEL

388

C. Tennant, D. Douglas, R. Li
JLab, Newport News, Virginia, USA
C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA

Funding: Work supported by the Office of Naval Research and the High Energy Laser Joint Technology. Jefferson Laboratory work is supported under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Laboratory IR FEL Driver provides an ideal test bed for studying a variety of beam dynamical effects. Recent studies focused on characterizing the impact of coherent synchrotron radiation (CSR) with the goal of benchmarking measurements with simulation. Following measurements to characterize the beam, we quantitatively characterized energy extraction via CSR by measuring beam position at a dispersed location as a function of bunch compression. In addition to operating with the beam on the rising part of the linac RF waveform, measurements were also made while accelerating on the falling part. For each, the full compression point was moved along the backleg of the machine and the response of the beam (distribution, extracted energy) measured. Initial results of start-to-end simulations using a 1D CSR algorithm show remarkably good agreement with measurements. A subsequent experiment established lasing with the beam accelerated on the falling side of the RF waveform in conjunction with positive momentum compaction (R56) to compress the bunch. The success of this experiment motivated the design of a modified CEBAF-style arc with control of CSR and microbunching effects.

MOPP140

Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector

emittance, coupling, electron, gun

391

A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
L. Faillace
RadiaBeam, Marina del Rey, California, USA
B. Spataro
INFN/LNF, Frascati (Roma), Italy
A. Valloni
CERN, Geneva, Switzerland

A new S-Band photoinjector is being developed at UCLA that will feature a large accelerating gradient at 160 MeV/m creating a beam with approximately 6.5 MeV at the exit. Because of the large accelerating gradient and other considerations, such as cooling and manufacturing, the new Supergun will be coupled into using a coaxial method, rather than side coupling. With the large accelerating gradient we hope to create very low emittance beams on the order of 0.025 mm mrad. These beams can then be used for a number of purposes, mainly for high quality beams used in FELs. Electric simulations have been done using HFSS and Superfish. Heating and mechanical simulations were done using Ansys. Finally, beam simulations were completed with GPT.

TUPP004

An In-flight Radioactive Ion Separator Design for the ATLAS Facility

dipole, ion, quadrupole, target

446

B. Mustapha, B. Back, C.R. Hoffman, B.P. Kay, 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.
An in-flight radioactive beam separator, named AIRIS, is being designed to enhance the radioactive beam capabilities of the ATLAS facility at Argonne. In order to serve all the experimental areas while maintaining the stable beam capabilities, the separator design is of broadband type. This design allows the selected radioactive beam to come back on the ATLAS beam line while stable beams continue on the same straight line with the separator turned off. The separation is performed in two steps, the first is magnetic in a chicane made of four magnets and four multipoles, while the second uses an rf sweeper taking advantage of the time separation between the beam of interest and potential contaminants including the primary beam tail. We will report on the progress of the AIRIS design effort with special emphasis on the performance of the rf sweeper.

TUPP006

Design of Relativistic Magnetron for High Power Microwave Generation

electron, extraction, cathode, cavity

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

cavity, 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]

TUPP020

Beam Dynamics Simulation for FLASH2 HGHG Option

FEL, undulator, radiation, electron

471

G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov
DESY, Hamburg, Germany
K.E. Hacker
DELTA, Dortmund, Germany
T. Plath
Uni HH, Hamburg, Germany

The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP022

RF Tuning of a S-band Hybrid Buncher for Injector Upgrade of LINAC II at DESY

linac, electron, target, experiment

478

Y.C. Nie, M. Hüning, C. Liebig, M. Schmitz
DESY, Hamburg, Germany

LINACII at DESY currently provides 450 MeV electrons for the synchrotron radiation source PETRAIII. The injector upgrade of it aims to improve its reliability and mitigate the radiological activation due to electron losses at hundreds of MeV. Therefore, a 2.998 GHz hybrid buncher has been developed and will be installed in between a pre-buncher and LINAC II. It comprises a 1-cell standing-wave (SW) section for rapid acceleration and a 13-cells travelling-wave (TW) section for further bunching and acceleration. This paper focuses on its rf tuning procedure. The tuning strategy combines a non-resonant bead-pull measurement of complex electric field and a linear model for local reflection coefficient calculation. The tuning result is satisfying. Field unflatness of the TW section has been improved from ±9% to ±4%, and field in the SW section has been enhanced significantly. By using ASTRA simulation, it has been verified that the residual detuning of the structure is acceptable in view of beam dynamics performance.

TUPP030

Design of a High Average Current Electron Source for the CLIC Drive Beam Injector

gun, cathode, emittance, electron

493

S. Döbert, N. Chritin
CERN, Geneva, Switzerland
B. Cadilhon, B. Cassany, J. Gardelle, K. Pepitone
CEA, LE BARP cedex, France

The drive beam injector for CLIC needs to deliver a 4.2 A electron beam for a duration of 140 μs with a repetition rate of 50 Hz. The shot to shot and flat top current stability has to be better than 0.1% to guarantee the beam stability required for CLIC. Based on the experience with the CTF3 injector a thermionic high voltage gun with a gridded cathode has been designed together with a sub-harmonic bunching system to achieve these requirements. The grid will allow controlling the current and eventually feedback on the flattop shape. The gun will operate at 140 kV and an emittance of 14 mm mrad can be obtained. The paper describes the design approach and the results of the systematic electromagnetic simulations to optimize the gun. Care was taken during the mechanical design of the gun to obtain a modular design allowing adjusting for different beam currents and cathode sizes.

TUPP036

Space Charge Compensation in the Linac4 LEBT for Three Injected Gas Types

emittance, ion, linac, space-charge

510

C.A. Valerio, R. Scrivens
CERN, Geneva, Switzerland
N. Chauvin
CEA/IRFU, Gif-sur-Yvette, France

The space charge of unbunched, high intensity beams can be compensated by the trapping of charged particles in the potential well of the beam. The source of these secondary charge particles can be the residual gas in the beam line. The effect is important in the Low energy beam transport (LEBT) regions. At CERN’s Linac4, the LEBT transports a pulsed 45keV H⁻ beam, which is compensated by the positive ions, created by collision of the beam with the neutral gas in the beam pipe. The rise time and amount of compensation may be varied by the density of neutral gas and the type of gas used (through the cross-section for ion production and the mass of the resulting ion). In this paper we present measurement results for the transport of the beam at the Linac4 LEBT with the addition of hydrogen, nitrogen and krypton gases into the line, and compare them with simulations of the beam dynamics including the effect of compensating positive ions . The H⁻ beam is provided by a cesiated 2MHz RF ion source with an external solenoidal antenna, operating with 600us pulses at 0.8Hz repetition rate.

Slides TUPP036 [4.084 MB]

Poster TUPP036 [1.356 MB]

TUPP038

Transverse Beam Profile Measurements in the Linac4 Medium Energy Beam Transport

emittance, linac, quadrupole, rfq

516

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

Linac4 is a 160 MeV H⁻ linear accelerator presently under construction at CERN. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The Linac4 front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) which accelerates the beam to 3 MeV and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been commissioned in the Linac4 tunnel. The MEBT is composed of three buncher cavities and 11 quadrupole magnets to match the beam from the RFQ to the next accelerating structure (DTL) and it includes two wire scanners for beam profile measurement. In this paper we present the results of the profile measurements and we compare them with emittance measurements taken with a temporary slit-and-grid emittance measurement device located after the MEBT line.

TUPP059

Advanced Beam Matching to a High Current RFQ

rfq, quadrupole, emittance, ion

559

S.G. Yaramyshev, W.A. Barth, L.A. Dahl, P. Gerhard, L. Groening, M.T. Maier, S. Mickat, A. Orzhekhovskaya, B. Schlitt, H. Vormann
GSI, Darmstadt, Germany

The High Current Injector (HSI) of the heavy ion linac UNILAC at GSI comprises the transport lines, the RFQ and two DTL tanks. Beam matching to the RFQ acceptance with a magnetic quadrupole quartet has been worked out manually during commissioning and operation of the machine. Due to a strong overlapping of the field from neighboring quadrupole lenses, a standard optics calculation does not provide for the required reliability. Advanced beam dynamics simulations have been done with the macroparticle code DYNAMION. The superposition of the measured magnetic fields of each quadrupole was taken into account. The quadrupole settings were optimized using the Monte-Carlo method. Two solutions have been found in accordance with the general theory of particle optics. Beam dynamics simulations with new quadrupole settings show an increased particle transmission through the RFQ. The results of numerical study have been confirmed during experimental campaigns. An improved performance of the whole HSI has been demonstrated. The proposed algorithm and a comparison of the measured data with result of simulations are presented.

TUPP060

Development of a 217 MHz Superconducting CH Structure

cavity, 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, cavity

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]

TUPP065

RF Input Power Couplers for High Current SRF Applications

cavity, booster, SRF, linac

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]

TUPP085

RAON Cryomodule Design for QWR, HWR, SSR1 and SSR2

cryomodule, linac, vacuum, cavity

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.

TUPP089

Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac

DTL, linac, cavity, 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

cavity, coupling, vacuum, rfq

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.

TUPP097

100-MeV Proton Beam Phase Measurement by Using Stripline BPM

linac, proton, DTL, coupling

656

H.S. Kim, Y.-S. Cho, H.-J. Kwon
KAERI, Daejon, Republic of Korea

Funding: This work is supported by Ministry of Science, ICT & Future Planning of the Korean Government.
In Korea Multipurpose Accelerator Complex (KOMAC), a 100-MeV proton linac, which is composed of a proton injector based on the microwave ion source, 3-MeV RFQ with a four-vane type and 100-MeV DTL with electromagnetic quadrupoles has been developed and currently provides the proton beam to users for various applications. To increase the beam power up to the design value, several improvements are required including the fine adjustment of the RF set-point during the operation. A stripline BPM is used for the beam phase measurement, where the pickup signals from four electrodes are combined by using the RF combiner, then mixed with 300 MHz LO reference signal resulting in 50 MHz IF signal which is processed by digital IQ demodulation method. In this paper, the details of the beam phase measurement setup and results will be presented.

TUPP103

The Beam Envelope Control in SC Linac for the Proton Radiotherapy

linac, controls, proton, cavity

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

cavity, gun, 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.

TUPP113

High RF Power Test of Coupled RFQ-SFRFQ Cavity

cavity, rfq, 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]

TUPP127

R&D of X-band Accelerating Structure for Compact XFEL at SINAP

FEL, linac, wakefield, radiation

715

W. Fang, Q. Gu, M. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
A.A. Aksoy, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
D. Angal-Kalinin, J.A. Clarke
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.J. Bocchetta, A.I. Wawrzyniak
Solaris, Kraków, Poland
M.J. Boland
SLSA, Clayton, Australia
G. D'Auria, S. Di Mitri, C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
T.J.C. Ekelöf, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
E.N. Gazis
National Technical University of Athens, Athens, Greece
A. Grudiev, A. Latina, D. Schulte, S. Stapnes, W. Wuensch
CERN, Geneva, Switzerland

One compact hard X-ray FEL facility is being planned at SINAP, and X-band high gradient accelerating structure is the most competetive scheme for this plan. X-band accelerating structure is designed to switch between 60MV/m and 80MV/m, and carries out 6GeV and 8GeV by 130 meters linac respectively. In this paper, brief layout of compact XFEL will be introduced, and in particular the prototype design of dedicated X-band acceleration RF system is also presented.

TUPP128

ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam

laser, radiation, electron, FEL

719

D. Huang, Q. Gu, Z. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

TUPP130

Optimization of Beam Parameters in APF Channel

linac, controls, emittance, rfq

722

V.V. Altsybeyev, D.A. Ovsyannikov
St. Petersburg State University, St. Petersburg, Russia

A new approach based on mathematical optimization methods to obtain a synchronous phase sequence in APF linacs is suggested. The optimization problem of intensity deuteron beam parameters is discussed. As an example, the results of beam dynamics simulations are presented.

THPP012

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

cavity, linac, electron, 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

cavity, dipole, damping, 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.

THPP014

Catalogue of Losses for the Linear IFMIF Prototype Accelerator

rfq, beam-losses, operation, distributed

860

N. Chauvin, P.A.P. Nghiem, D. Uriot
CEA/IRFU, Gif-sur-Yvette, France
M. Comunian
INFN/LNL, Legnaro (PD), Italy
C. Oliver
CIEMAT, Madrid, Spain

One of the activities of the EVEDA (Engineering Validation and Engineering Design Activities) phase of the IFMIF (International Fusion Materials Irradiation Facility) project consists in building, testing and operating, in Japan, a 125 mA/9 MeV deuteron accelerator, called LIPAc, which has been developed in Europe. For the accelerator safety aspects, a precise knowledge of beam loss location and power deposition is crucial, especially for a high intensity, high power accelerator like LIPAc. This paper presents the beam dynamics simulations allowing to estimate beam losses in different situations of the accelerator lifetime: starting from scratch, beam commissioning, tuning or exploration, routine operation, sudden failure. Some results of these studies are given and commented. Recommendations for hot point protection, beam stop velocity, beam power limitation are given accordingly.

Slides THPP014 [4.780 MB]

THPP025

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

cavity, pick-up, coupling, factory

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.

THPP028

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

cavity, beam-loading, 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

cavity, 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]

THPP033

Linac4 Transverse and Longitudinal Emittance Reconstruction in the Presence of Space Charge

emittance, linac, quadrupole, rfq

913

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

Linac4 is a pulsed, normal-conducting 160 Mev H⁻ linear accelerator presently under construction at CERN. It will replace the present 50 MeV Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The 3 MeV front end, composed of a 45 keV ion source, a Low Energy Beam transport (LEBT), a 352 MHz Radio Frequency Quadrupole (RFQ) at 3 MeV and Medium Energy Beam Transport (MEBT) housing a beam chopper, and the first Drift Tube Linac (DTL) tank at 12 MeV have been commissioned during the first half of 2014. The transverse and longitudinal emittance reconstruction technique in the presence of space charge, that will be used for the next commissioning stages and permanently during the Linac operation, was successfully tested and validated. The reconstruction method and the results obtained at 3 and 12 MeV are presented in this paper.

THPP043

Benchmark of the Beam Dynamics Code DYNAC Using the ESS Proton Linac

linac, rfq, space-charge, DTL

945

E. Tanke, R. De Prisco, M. Eshraqi, R. Miyamoto, A. Ponton, E. Sargsyan
ESS, Lund, Sweden
S. Valero
CEA, Gif-sur-Yvette, France

The beam dynamics code DYNAC is benchmarked using the ESS Proton Linac. Recent work on improvements in the code, including of the RFQ model, is discussed. The three space charge routines contained in DYNAC, including a 3D version, have remained unchanged. The code contains a numerical method, capable of simulating a multi-charge state ion beam in accelerating elements. In addition, protons, single charge state heavy ions and non-relativistic electrons in accelerating elements can be modeled using an analytical method. The benchmark will include comparisons of both methods with the beam dynamics models in use at ESS: TraceWin and Toutatis. As this analytical method used in DYNAC is fast, it is a prime candidate for use as an online beam simulation tool.

THPP048

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

cavity, operation, resonance, 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, cavity, 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.

THPP055

High Power Density Test of PXIE MEBT Absorber Prototype

radiation, electron, experiment, focusing

973

A.V. Shemyakin, C.M. Baffes
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy
One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. Two prototypes of the absorber were manufactured from molybdenum alloy TZM, and tested with a 28 keV DC electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototypes and key testing results.

THPP060

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

HOM, cavity, 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.

THPP069

Status and Outlook of the 325 MHz 4-Rod RFQ

rfq, dipole, HOM, impedance

1010

B. Koubek, H. Podlech, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

In order to built a Radio Frequency Quadrupole (RFQ) at 325 MHz for the FAIR proton linac, a 4-rod structure has been investigated. The RF design, especially the dipole and fringe fields and higher order modes, has been studied with simulations. A prototype has been built and power tested to verify the simulation results and investigate the high power performance. This paper summarizes the results of the research concerning the 325 MHz 4-rod RFQ and gives an overview about the next steps in this project.

THPP071

Proposal of a 325 MHz Ladder-RFQ for the FAIR Proton-Linac

rfq, proton, dipole, quadrupole

1016

M. Schütt, U. Ratzinger
IAP, Frankfurt am Main, Germany
R. M. Brodhage
GSI, Darmstadt, Germany

Funding: BMBF 05P12RFRB9
For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The first rf accelerator element is a 325 MHz RFQ accelerating from 95 keV to 3.0 MeV. RFQ’s beyond 300 MHz were realized in 4-Vane-type geometry so far. At IAP there is a tradition in 4-Rod-type RFQ development. This type of RFQ is dominating at lower frequencies. Very promising results have been reached with a ladder type-RFQ, which has been investigated during 2013. In comparison with a traditional 4-Rod RFQ approach the geometry is more convenient at high frequencies. We will show most recent 3D simulations of the frequency tuning possibilities and of a whole cavity demonstrating the power of a ladder type RFQ. An RFQ layout for the new FAIR proton injector will be shown. (see also R. Brodhage, U. Ratzinger, A. Almomani, “Design Study of a High Frequency Proton Ladder RFQ” , Proc. of the 2013 IPAC Conference, Shanghai, China, p. 3788.)

THPP075

Development of Superconducting Spoke Cavity for Electron Accelerators

cavity, 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

cavity, operation, 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.

THPP079

Prototyping Progress of SSR1 Single Spoke Resonator for RAON

cavity, target, 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.

THPP084

Cyclotron-Undulator Cooling of Electron Beams

undulator, electron, cyclotron, FEL

1041

S.V. Kuzikov, I.V. Bandurkin, A.V. Savilov
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

XFELs require high-quality electron beams which can be produced in damping rings. For XFEL, based on Compton scattering of laser light, instead of the damping ring we consider a new compact device where electrons move in the undulator with axial DC magnetic field. In this undulator electrons move near resonant condition, rotating with cyclotron frequency and wiggling at similar bounce frequency. Such undulator allows compensation of the initial velocity spread by perturbations of the longitudinal velocities caused by transverse wiggling. Calculation show that ~1% velocity spread of 5 MeV electron beam (typical for photoinjectors) can be reduced to ~0.01% at distance as long as 20 undulator periods. In the advanced scheme, where the described undulators alternate with sections of the cyclotron radiation, energy spread as small as 0.001% is reachable. Calculations show that this principle works also for high energy beams (100 MeV and more), where RF undulator instead of DC-magnet undulator is preferable.

Poster THPP084 [0.713 MB]

THPP085

The Prototype of the Proton Injector for the European Spallation Source

plasma, proton, extraction, emittance

1044

L. Celona, L. Andò, G. Castro, S. Gammino, D. Mascali, L. Neri, G. Torrisi
INFN/LNS, Catania, Italy

The update of the design of the PS-ESS source and of its LEBT has been carried out in 2013 and the construction is now ongoing. The Ion Source will be able to provide a proton beam current larger than 70 mA to the 3.6 MeV RFQ. Several innovative solutions have been implemented in the redesign phase in order to cope with high-reliability/high-performance requirements of the ESS project. A flexible magnetic system will allow to investigate alternative configurations for future ion current upgrade of the machine based on the formation of a denser plasma. Innovative set-ups have been also explored for beam extraction, transport and chopping. Calculations have shown that space charge compensation up to 95 % is needed to preserve the low emittance in the low energy beam transfer line (LEBT). In order to obtain the optimal proton beam pulse rise and fall time – that should be 100 ns – we propose a LEBT chopping configuration that permits hundred nanosecond rise times despite the LEBT compensation needs few microseconds. The ongoing development of a 3D PIC code will be also described, that should allow predicting and tuning the beam pulse for different source/LEBT operative configurations.

THPP090

Longitudinal Measurement of Annular-Ring Coupled Structure Linac in J-PARC

injection, linac, distributed, rfq

1056

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

In the J-PARC linac, Annular-type Coupled Structure (ACS) linac was introduced for the beam energy extension to 400 MeV in year 2013. To measure the longitudinal property of the ACS, we measured acceptance in phase direction by synchronous phase scan method and confirm that the acceptance is consistent with that by 3D PIC simulation. Simultaneously, the output beam energy from ACS was measured by orbit displacement where the dispersion is large. In this presentation, we discuss the measurement method and results.

THPP095

Design Study of Superconducting Linear Accelerator for Unstable Ion Beams in RISP

linac, emittance, ion, ISOL

1071

J.G. Hwang, C. Kim, E.-S. Kim
Kyungpook National University, Daegu, Republic of Korea
B.H. Choi, H. Jang, D. Jeon, H.J. Kim, H.J. Kim, I. Shin
IBS, Daejeon, Republic of Korea
L. Lee
KNU, Deagu, Republic of Korea

The post accelerator of RAON can accelerate the unstable and stable ion beams up to 15 MeV/u for 132Sn¹⁶⁺ and 58Ni⁸⁺ for 16.5 MeV/u, which has the ratio of mass to charge, A/q, of 8.3. The unstable ion beam such as 132Sn¹⁶⁺ produced by an ISOL system has the large transverse and longitudinal emittances. The post-accelerator consists of post-LEBT, RFQ, MEBT and superconduction linac(SCL3 and we optimized acceptance and beam envelope based on the beam dynamics in the linac. The accelerated beam by post accelerator was transported by the post-to-driver transport (P2DT) line which consists of a charge stripper, two charge selection sections and a telescope section with the bunching cavities to the high energy linac(SCL2) and accelerated up to 200 MeV/u. In this presentation, we will show the criteria for the design of the post accelerator and result of beam tracking simulation from post-LEBT to end of high energy linac.

THPP097

3D Effects in RFQ Accelerators

rfq, quadrupole, cavity, 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.

THPP104

Simulation of the Electron Beam Dynamics in the Biperiodical Structure

electron, coupling, Windows, impedance

1096

Yu.D. Kliuchevskaia, T.V. Bondarenko, S.M. Polozov
MEPhI, Moscow, Russia

А biperiodical accelerating structure (BAS) with operating frequency 27 GHz for the 6 MeV compact radiotherapy electron accelerator is considered. The operating frequency 27 GHz allows to significantly reduce the facility sizes, unlike the S-, X- and C-band operating linacs. The optimal geometrical parameters of BAS necessary for π/2 mode were defined by means of accelerating and coupling cell tuning. The BAS coupler was also simulated. Results of the electron beam dynamics analysis in designed structure are also discussed.

THPP105

Beam Dynamics Simulation for the 1 GeV High Power Proton Linac

linac, focusing, rfq, proton

1099

S.M. Polozov, V.S. Dyubkov, T. Kulevoy, A.V. Samoshin
MEPhI, Moscow, Russia
G. Kropachev, T. Kulevoy
ITEP, Moscow, Russia

Funding: This work is supported in part by the Ministry of Science and Education of Russian Federation under contract No. 14.516.11.0084
The design of high energy and high power proton linacs for accelerating driven systems (ADS) is one of the accelerator technology frontiers. Such linacs are under developing in EU, Japan, PRC but not discussed in Russia previous fifteen years. The driver linac and the breeder conceptual designs were funded by the Ministry of Science and Education of Russian Federation in 2013. The 2 MeV RFQ linac was proposed as the first accelerating section. A number of RF focusing sections types (by RF crossed lenses, modified electrode profile RFQ, axi-symmetrical RF focusing) were discussed for medium energies. The conventional modular scheme linac based on spoke-cavities and 5-cell elliptical cavities was designed for higher energies. The results of beam dynamics simulation in this linac will present.

THPP112

Multipacting Optimization of a 750 MHz RF Dipole

dipole, cavity, 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.

THPP120

Status of Radio-Frequency (RF) Deflectors at Radiabeam

electron, cavity, 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.

THPP126

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

cavity, gun, 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.

THPP129

Carbon Field Emission Strip Cathode Electron Source

electron, cathode, vacuum, focusing

1

T.V. Bondarenko, A.I. Botyachkova, G.G. Karpinskiy, S.A. Polikhov, G.B. Sharkov
Siemens Research Center, Moscow,, Russia
A.I. Botyachkova, G.G. Karpinskiy
National Research Nuclear University (MEPhI), Moscow, Russia
A.E. Geisler, O. Heid
Siemens AG, Erlangen, Germany

Over the recent years carbon nanostructure cathodes have become promising as a high brightness electron sources with large working area for field emission structures. Measurements and calculations of a field emission strip cathode based on carbon structure and a unit for its investigation are presented in the article. For measuring of the cathode emitting properties and determination of the electrons initial parameters used in the electron beam computer simulation the experimental setup is been developed. The setup consists of the high-voltage triode electrode system and allows to investigate the voltage-current characteristics of the cathode and to estimate the electron distribution of the beam on the anode surface. The anode electron distribution evaluations are processed by the measurements of the emitted X-ray focal spot on the anode by application of the CCD camera. Verification of the simulated electron beam dynamics can be obtained by application of the experimentally acquired data.

Poster THPP129 [4.088 MB]

THPP138

Measurements of Beam Current and Energy-Dispersion for Ion Beam with Multi-Components

ion, ion-source, vacuum, experiment

1185

A.L. Zhang
University of Chinese Academy of Sciences, Beijing, People's Republic of China
J.E. Chen, Z.Y. Guo, S.X. Peng, H.T. Ren, Y. Xu, T. Zhang, J. Zhao
PKU, Beijing, People's Republic of China
J.E. Chen
Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China

Funding: This work is supported by the National Science Foundation of China（Grant Nos. 91126004).
The multi-component ion beam is very common in nuclear physics, materials physics and most kind of ion source. But the diagnosis of multi-component ion beam [1] can be difficult because of its complex composition and irregular energy-dispersion. We need an effective way to analyzing the multi-component ion beam. There is a multi-component ion beam whose total beam current varies from 1 mA to 50mA and the beam energy can be 20keV to 150keV. In this paper, four methods to analyzing this multi-component ion beam are described, which are Faraday cup array method, fluorescent screen with Faraday cup, movable aperture with conductive fluorescent screen, and current calibration method, respectively. The distributions and currents of the separated ion beams are obtained by means of the four methods, and the current and energy-dispersion of each component might be measured at the same time. This is of special interest for beams with multi-components. Detailed description and comparison of the four methods are discussed in this paper.
Correspondence Author:Peng ShiXiang.
Email: sxpeng@pku.edu.cn

Poster THPP138 [0.419 MB]

FRIOB01

Positive Trends in Radiation Risk Assessment and Consequent Opportunities for Linac Applications

radiation, linac, FEL, controls

1202

Y. Socol
Falcon Analytics, Netanya, Israel

Ionizing radiation, an unavoidable by-product of high-energy LINACs, makes them subject to strict regulation and severe public concerns. During the last two decades the attitude to ionizing radiation hazards has been becoming more balanced, as opposed to the historical "radiophobia". The linear no-threshold hypothesis (LNTH), based on the assumption that every radiation dose increment constitutes increased cancer risk for humans, is more and more debated. In particular, the recent memorandum of the International Commission on Radiological Protection admits that the LNTH predictions at low doses are "speculative, unproven, undetectable and "phantom'." Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of ionizing radiation may be beneficial to human health. While these advances in scientific understanding have not yet given fruit regarding radiation regulation and policy, we are hopeful these may happen in near to middle term. The presentation reviews the present status of the low-dose radiation-hazard debate. It also outlines anticipated opportunities for LINAC applications, especially in the prospective field of low-dose radiation therapy.

Slides FRIOB01 [1.890 MB]