LINAC2014 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOIOC02	Single-Knob Beam Line for Transverse Emittance Partitioning	emittance, solenoid, quadrupole, scattering	36
	C. Xiao, L. Groening, O.K. Kester, H. Leibrock, M.T. Maier, P. Rottländer GSI, Darmstadt, Germany M. Chung UNIST, Ulsan, Republic of Korea
	Flat beams feature unequal emittances in the horizontal and vertical phase space. Such beams were created successfully in electron machines by applying effective stand-alone solenoid fringe fields in the electron gun. Extension of this method to ion beams was proposed conceptually. The present paper is on the decoupling capabilities of an ion beam emittance transfer line. The proposed beam line provides a single-knob tool to partition the horizontal and vertical rms emittances, while keeping the product of the two emittances constant as well as the transverse rms Twiss parameters (αx,y and βx,y) in both planes. It is shown that this single knob is the solenoid field strength, and now we fully understand the decoupling features.
	Slides MOIOC02 [1.327 MB]

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

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

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

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

MOPP053	TTF-III Coupler Modification for CW Operation	simulation, operation, resonance, 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.

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

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

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

MOPP125	Comparison of Normal Conducting High Energy Accelerating Structures for a Moderate Operating Frequency	linac, Windows, proton, impedance	348
	V.V. Paramonov RAS/INR, Moscow, Russia
	The progress in the CERN Linac 4 project confirms the very attractive possibility for single frequency high intensity high energy normal conducting hadron linac. The important part of such linac is the accelerating structure for high energy part. Parameters of possible accelerating structures, referring to PIMS, at operating frequency 352 MHz are considered for proton energy up to 600 MeV. The set of parameters, such as dimensions, RF efficiency, field stability, cooling capability, vacuum conductivity, are considered and compared.

MOPP140	Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector	emittance, electron, simulation, 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.

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

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

TUPP097	100-MeV Proton Beam Phase Measurement by Using Stripline BPM	linac, proton, DTL, simulation	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.

TUPP116	Status of the FERMI II RF Gun at Sincrotrone Trieste	gun, cathode, emittance, dipole	692
	L. Faillace, R.B. Agustsson, P. Frigola, A. Verma RadiaBeam, Santa Monica, California, USA
	Radiabeam Technologies, in collaboration with UCLA, developed a high gradient normal conducting radio frequency (NCRF) 1.6 cell photoinjector system, termed the Fermi Gun II, for the Sincrotrone Trieste (ST) facility. The RF gun has been already in full operation since mid-2013 as the injector for the ST FEL. We report here the current status of the photoinjector system.

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

THPP018	Sample Plate Studies Using a High Field TE Cavity With Thermometry Mapping System	cavity, niobium, SRF, experiment	873
	D.L. Hall, C.D. Burton, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: NSF Career Grant PHY-0841213 A TE-Mode sample plate cavity capable of sustaining peak fields of >90 mT on the surface of a 10cm diameter sample plate has been developed and tested at Cornell. A thermometry mapping system composed of 40 Allen-Bradley resistors, mounted on the outside of the sample plate, is capable of measuring the surface resistance of the sample with a resolution of 1 nOhm and a spatial resolution of 0.5 cm. In this paper we present the design and expected performance of this high field TE cavity, and show data taken with a sample plate of niobium as well as results from tests qualifying the performance of the thermometry mapping system.

THPP025	RF Design and Low Power Measurements of a Nose-Cone Single Gap Buncher Cavity	cavity, pick-up, factory, simulation	888
	O. González, I. Bustinduy, N. Garmendia, P.J. González, L. Muguira, J.L. Muñoz, A. Zugazaga ESS Bilbao, Zamudio, Spain
	A nose-cone single-gap buncher cavity for the Medium Energy Beam Transport (MEBT) has been fully designed, manufactured and measured under low-power conditions at ESS-Bilbao. The main steps of the design process are first reviewed. Second, the cavity is thoroughly measured and characterized by means of an automatic test procedure based on the bead-pull technique. Third, the simulated and measured results obtained for the main figures of merit are compared. Specifically, the results for the resonant frequency, the coupling and quality factors, the electric field profile, the R over Q ratio, the transit time factor and the tuning range are carefully analysed.

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

THPP049	Design of 162.5 MHz CW Main Coupler for RFQ	rfq, simulation, cavity, 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.

THPP061	RF Design of a Novel S-Band Backward Traveling Wave Linac for Proton Therapy	linac, accelerating-gradient, proton, impedance	992
	S. Benedetti, U. Amaldi TERA, Novara, Italy A. Degiovanni, A. Grudiev, W. Wuensch CERN, Geneva, Switzerland
	Proton therapy is a rapidly developing technique for tumour treatment, thanks to the physical and dosimetric advantages of charged particles in the dose distribution. Here the RF design of a novel high gradient accelerating structure for proton Linacs is discussed. The choice of a linear accelerator lies mainly in its advantage over cyclotron and synchrotron in terms of fast energy modulation of the beam, which allows the implementation of active spot scanning technique without need of passive absorbers. The design discussed hereafter represents a unicum thanks to the accelerating mode chosen, a 2.9985 GHz backward traveling wave mode with 150° phase advance, and to the RF design approach. The prototype has been designed to reach an accelerating gradient of 50 MV/m, which is more than twice that obtained before. This would allow a shorter Linac potentially reducing cost. The complete 3D RF design of the full structure for beta equal to 0.38 is presented. A prototype will be soon produced and tested at high power. This structure is part of the TULIP project, a proton therapy single-room facility based on high gradient linear accelerators.
	Slides THPP061 [1.537 MB]

THPP078	Troubleshooting and Performances of Type-B Spiral2 Series Cryomodule	cavity, cryomodule, pick-up, resonance	1037
	D. Longuevergne, F. Chatelet, C. Commeaux, N. Gandolfo, D. Grolet, C. Joly, J. Lesrel, R. Martret, G. Michel, G. Olry, L. Renard, A. Stephen, P. Szott IPN, Orsay, France
	SPIRAL2 aims at building a multi-purpose facility dedicated to nuclear physics studies, including the production of rich-neutrons isotopes. The multi-beam linear accelerator is composed of superconducting accelerating modules operating at 4.2K and warm focusing magnets. IPN Orsay is in charge of the high energy (Type-B) accelerating modules, each hosting two superconducting 88 MHz quarter-wave resonators made of bulk Niobium operating at an accelerating gradient of 6.5 MV/m (β=0.12). The first Type-B series cryomodule has been validated in April 2013. Since then, four additional cryomodules have been validated in a row showing a very high-quality and reliable assembly procedure. Some of encountered problems (tuner hysteresis, magnetic shielding,) and associated solutions will be presented. Moreover, a comparison of cavity performances between vertical cryostat and cryomodule tests will be done.

THPP087	ESS DTL Design and Drift Tube Prototypes	DTL, linac, vacuum, quadrupole	1050
	F. Grespan, M. Comunian, A. Pisent, M. Poggi, C. R. Roncolato INFN/LNL, Legnaro (PD), Italy P. Mereu INFN-Torino, Torino, Italy
	The Drift Tube Linac (DTL) for the ESS accelerator will accelerate protons up to 62.5 mA average pulse current from 3.62 to 90 MeV. The 5 tanks composing the DTL are designed to operate at 352.2 MHz in pulses of 2.86 ms long with a repetition rate of 14 Hz. The accelerating field is around 3.1 MV/m, constant in each tank. Permanent magnet quadrupoles (PMQs) are used as focusing element in a FODO lattice. The empty drift tubes accommodate Electro Magnetic Dipoles (EMDs) and Beam Position Monitors (BPMs) in order to implement beam corrective schemes. A complete set of Drift Tubes is under construction that is BPM, EMD and PMQ types. These prototypes are aimed to validate the design with the involved integration issues of the various components, as well as the overall technological and assembly process. This paper presents the main mechanical choices and the status of the prototyping program of the Drift Tubes.

THPP089	High Power Conditioning of Annular-Ring Coupled Structures for the J-PARC Linac	vacuum, operation, linac, cavity	1053
	H. Ao, T. Ito, Y. Nemoto, H. Oguri, N. Ouchi, J. Tamura JAEA/J-PARC, Tokai-mura, Japan H. Asano Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan Z. Fang, K. Futatsukawa, K. Nanmo, T. Sugimura KEK, Ibaraki, Japan
	The linac of Japan Proton Accelerator Research Complex (J-PARC), which is an injector to a 3-GeV synchrotron, comprised a 3-MeV RFQ, 50-MeV DTLs and 181-MeV Separated-type DTLs. From September 2013, 25 annular-ring coupled structure (ACS) cavities were additionally installed to increase the linac beam energy up to 400 MeV and achieve 1-MW beam power of the 3-GeV synchrotron. After installation work the high power conditioning was started from December 2013 and most of the ACS cavities were conditioned within three weeks. We passed through some troubles and finally finished conditioning all the cavities until the middle of January 2014. In this paper, we present the conditioning results and how to handle the issue in the conditioning process.
	Slides THPP089 [7.756 MB]

THPP096	RF Coaxial Resonator for Investigating Multipactor Discharges on Metal and Dielectric Surfaces	multipactoring, electron, vacuum, experiment	1074
	M. El Khaldi, W. Kaabi, P. Lepercq, Y. Peinaud LAL, Orsay, France
	Multipactor discharge is a phenomenon in which electrons impact one or more material surfaces in resonance with an alternating electric field. The discharge can occur for a wide range of frequencies, from the MHz range to tens of GHz, and in wide array of geometries if the impacted surface has a secondary electron emission (SEE) yield larger than one. The discharge can take place on a single surface or between two surfaces. A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF power. These experiments were successful in identifying multipacting and allowed us the evaluation of a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor.

THPP104	Simulation of the Electron Beam Dynamics in the Biperiodical Structure	electron, simulation, 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.

THPP114	The SwissFEL RF Gun: Manufacturing and Proof of Precision by Field Profile Measurements	gun, electron, cathode, vacuum	1117
	U. Ellenberger, H. Blumer, M. Kleeb, L. Paly, M. Probst Paul Scherrer Institute, Villigen PSI, Switzerland M. Bopp, A. Citterio, H. Fitze, J.-Y. Raguin, A. Scherer, L. Stingelin PSI, Villigen PSI, Switzerland
	The high brightness electron source for SwissFEL is an in-house built 2.6 cell normal-conducting RF gun which is scaled to the RF frequency of 2'998.8 MHz. The RF gun is capable of operating at 100 Hz repetition rate and produces electron bunches at the exit of the RF gun of an energy of 7 MeV. Key features of the RF gun are described and how they have been implemented in the manufacturing process. RF field measurements of the RF gun are presented to account for the mechanical precision reached after manufacturing. The RF gun has been thoroughly tested in the SwissFEL injector test facility.

THPP125	Super-Compact SLED System Used in the LCLS Diagnostic System	cavity, electron, klystron, impedance	1151
	J.W. Wang, S.G. Tantawi, C. Xu SLAC, Menlo Park, California, USA
	Funding: * Work supported by Department of Energy contract DE–AC03–76SF00515. At SLAC, we have designed and installed an X-band radio-frequency transverse deflector system at the LCLS for measurement of the time-resolved lasing effects on the electron beam and extraction of the temporal profile of the pulses in routine operations. We have designed an X-Band SLED system capable design to augment the available klystron power and to double the kick.

THPP127	The Status of the Construction of MICE Step IV	solenoid, emittance, experiment, cavity	1159
	S. Ricciardi STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Funding: NSF, DOE, STFC, INFN and more The International Muon Ionisation Cooling Experiment in its next step IV will provide the first precise measurements of emittances and first evidence of cooling in 2015. The pair of MICE "emittometers" must be in place for this, upstream and downstream of the ionization cooling module. Each required the construction of a tracker (sci-fibers) measuring muon helices in solenoid coils that surround it. Solenoid coils confine muons to spiral in all components of a ionization cooling module. The first of these, that is now ready for Step IV, will be the first of three AFC (absorber-focus coil) modules: a Li-H vessel inside its own FC "focusing" coils. Li-H and other simpler, possibly competitive, liquid and solid absorber samples are also being prepared. The assembly process is in progress. Construction, performances, lessons learned will be described. Final step V and step VI demonstration requires two more AFC modules and two re-acceerating modules, RFCC's made of RF cavities inside their own focusing CC ("coupling" coils). The choices made and challenges being faced in this longer term construction efforts simultaneosly in progress will also briefly be pointed to. The abstract is submitted by the chair of the MICE Speakers Bureau. The presentation would be delivered by Dr Stefania Ricciardi (RAL) Promotion to Oral would be most welcome

THPP140	High Transparent Matched Window for Standing Wave Linear Accelerators	linac, electron, vacuum, network	1192
	A. Leggieri, F. Di Paolo, D. Passi Università degli Studi di Roma "Tor Vergata", Roma, Italy A. Ciccotelli, G. Felici S.I.T., Aprilia, Italy
	This paper proposes a particular Dielectric Window (DW) for Standing Wave (SW) Linear Accelerators (LINAC’s). This study investigates the in-frequency return loss behavior of the LINAC, in order to improve matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design is single-frequency based and considers the DW interface as an Input Matching Network (IMN) at the LINAC Normal Mode (NM) working frequency. Thus, design formulas are provided and Computer Aided Design (CAD) techniques are proposed. A prototype has been made and tested by performing cold S-parameter and Percentage Depth Dose (PDD) measurements of a LINAC with the proposed DW and with a traditional DW. The proposed device offers more energy transport attitude over the traditional DW, as shown by a return loss increase of 167% and an output electron energy increase of 5.5% while maintaining the same LINAC input power settings. This solution can offer a decrease of power line size, weight and cost. An after brazing global improvement of the accelerator figures of merit is also possible, as this study have demonstrated. [1]Hiroyuki Arai, 1986 [2]K. Hirano, 1995 [3]Y. Otake, 1995 [5]A. Leggieri, 2014 [6]A. C. Ugural, 2003 [7]A. Leggieri, 2014 [8]F. Di Paolo, 2000 [9]N. Marcuvitz, 1951

Paper

Title

Other Keywords

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MOIOC02

Single-Knob Beam Line for Transverse Emittance Partitioning

emittance, solenoid, quadrupole, scattering

36

C. Xiao, L. Groening, O.K. Kester, H. Leibrock, M.T. Maier, P. Rottländer
GSI, Darmstadt, Germany
M. Chung
UNIST, Ulsan, Republic of Korea

Flat beams feature unequal emittances in the horizontal and vertical phase space. Such beams were created successfully in electron machines by applying effective stand-alone solenoid fringe fields in the electron gun. Extension of this method to ion beams was proposed conceptually. The present paper is on the decoupling capabilities of an ion beam emittance transfer line. The proposed beam line provides a single-knob tool to partition the horizontal and vertical rms emittances, while keeping the product of the two emittances constant as well as the transverse rms Twiss parameters (αx,y and βx,y) in both planes. It is shown that this single knob is the solenoid field strength, and now we fully understand the decoupling features.

Slides MOIOC02 [1.327 MB]

MOPP020

Input Couplers for Cornell ERL

linac, cryomodule, cavity, impedance

95

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

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

MOPP035

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

cavity, electromagnetic-fields, simulation, extraction

134

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

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

MOPP046

On the Design of Higher Order Mode Antenna for LCLS II

HOM, cavity, higher-order-mode, simulation

161

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

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

MOPP052

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

cavity, linac, HOM, accelerating-gradient

171

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

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

MOPP053

TTF-III Coupler Modification for CW Operation

simulation, operation, resonance, 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.

MOPP059

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

cavity, proton, linac, resonance

187

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

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

MOPP090

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

cavity, simulation, linac, ion

264

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

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

MOPP118

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

impedance, cavity, klystron, vacuum

329

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

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

MOPP125

Comparison of Normal Conducting High Energy Accelerating Structures for a Moderate Operating Frequency

linac, Windows, proton, impedance

348

V.V. Paramonov
RAS/INR, Moscow, Russia

The progress in the CERN Linac 4 project confirms the very attractive possibility for single frequency high intensity high energy normal conducting hadron linac. The important part of such linac is the accelerating structure for high energy part. Parameters of possible accelerating structures, referring to PIMS, at operating frequency 352 MHz are considered for proton energy up to 600 MeV. The set of parameters, such as dimensions, RF efficiency, field stability, cooling capability, vacuum conductivity, are considered and compared.

MOPP140

Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector

emittance, electron, simulation, 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.

TUPP073

Study of the ACS Cavity Without a Bridge Cavity

cavity, linac, proton, alignment

596

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

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

Slides TUPP073 [5.042 MB]

TUPP093

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

cavity, vacuum, rfq, simulation

643

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

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

TUPP097

100-MeV Proton Beam Phase Measurement by Using Stripline BPM

linac, proton, DTL, simulation

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.

TUPP116

Status of the FERMI II RF Gun at Sincrotrone Trieste

gun, cathode, emittance, dipole

692

L. Faillace, R.B. Agustsson, P. Frigola, A. Verma
RadiaBeam, Santa Monica, California, USA

Radiabeam Technologies, in collaboration with UCLA, developed a high gradient normal conducting radio frequency (NCRF) 1.6 cell photoinjector system, termed the Fermi Gun II, for the Sincrotrone Trieste (ST) facility. The RF gun has been already in full operation since mid-2013 as the injector for the ST FEL. We report here the current status of the photoinjector system.

WEIOA01

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

linac, vacuum, cavity, quadrupole

746

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

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

Slides WEIOA01 [4.909 MB]

THPP018

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

cavity, niobium, SRF, experiment

873

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

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

THPP025

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

cavity, pick-up, factory, simulation

888

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

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

THPP028

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

cavity, beam-loading, simulation, 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.

THPP049

Design of 162.5 MHz CW Main Coupler for RFQ

rfq, simulation, cavity, 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.

THPP061

RF Design of a Novel S-Band Backward Traveling Wave Linac for Proton Therapy

linac, accelerating-gradient, proton, impedance

992

S. Benedetti, U. Amaldi
TERA, Novara, Italy
A. Degiovanni, A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland

Proton therapy is a rapidly developing technique for tumour treatment, thanks to the physical and dosimetric advantages of charged particles in the dose distribution. Here the RF design of a novel high gradient accelerating structure for proton Linacs is discussed. The choice of a linear accelerator lies mainly in its advantage over cyclotron and synchrotron in terms of fast energy modulation of the beam, which allows the implementation of active spot scanning technique without need of passive absorbers. The design discussed hereafter represents a unicum thanks to the accelerating mode chosen, a 2.9985 GHz backward traveling wave mode with 150° phase advance, and to the RF design approach. The prototype has been designed to reach an accelerating gradient of 50 MV/m, which is more than twice that obtained before. This would allow a shorter Linac potentially reducing cost. The complete 3D RF design of the full structure for beta equal to 0.38 is presented. A prototype will be soon produced and tested at high power. This structure is part of the TULIP project, a proton therapy single-room facility based on high gradient linear accelerators.

Slides THPP061 [1.537 MB]

THPP078

Troubleshooting and Performances of Type-B Spiral2 Series Cryomodule

cavity, cryomodule, pick-up, resonance

1037

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

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

THPP087

ESS DTL Design and Drift Tube Prototypes

DTL, linac, vacuum, quadrupole

1050

F. Grespan, M. Comunian, A. Pisent, M. Poggi, C. R. Roncolato
INFN/LNL, Legnaro (PD), Italy
P. Mereu
INFN-Torino, Torino, Italy

The Drift Tube Linac (DTL) for the ESS accelerator will accelerate protons up to 62.5 mA average pulse current from 3.62 to 90 MeV. The 5 tanks composing the DTL are designed to operate at 352.2 MHz in pulses of 2.86 ms long with a repetition rate of 14 Hz. The accelerating field is around 3.1 MV/m, constant in each tank. Permanent magnet quadrupoles (PMQs) are used as focusing element in a FODO lattice. The empty drift tubes accommodate Electro Magnetic Dipoles (EMDs) and Beam Position Monitors (BPMs) in order to implement beam corrective schemes. A complete set of Drift Tubes is under construction that is BPM, EMD and PMQ types. These prototypes are aimed to validate the design with the involved integration issues of the various components, as well as the overall technological and assembly process. This paper presents the main mechanical choices and the status of the prototyping program of the Drift Tubes.

THPP089

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

vacuum, operation, linac, cavity

1053

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

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

Slides THPP089 [7.756 MB]

THPP096

RF Coaxial Resonator for Investigating Multipactor Discharges on Metal and Dielectric Surfaces

multipactoring, electron, vacuum, experiment

1074

M. El Khaldi, W. Kaabi, P. Lepercq, Y. Peinaud
LAL, Orsay, France

Multipactor discharge is a phenomenon in which electrons impact one or more material surfaces in resonance with an alternating electric field. The discharge can occur for a wide range of frequencies, from the MHz range to tens of GHz, and in wide array of geometries if the impacted surface has a secondary electron emission (SEE) yield larger than one. The discharge can take place on a single surface or between two surfaces. A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF power. These experiments were successful in identifying multipacting and allowed us the evaluation of a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor.

THPP104

Simulation of the Electron Beam Dynamics in the Biperiodical Structure

electron, simulation, 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.

THPP114

The SwissFEL RF Gun: Manufacturing and Proof of Precision by Field Profile Measurements

gun, electron, cathode, vacuum

1117

U. Ellenberger, H. Blumer, M. Kleeb, L. Paly, M. Probst
Paul Scherrer Institute, Villigen PSI, Switzerland
M. Bopp, A. Citterio, H. Fitze, J.-Y. Raguin, A. Scherer, L. Stingelin
PSI, Villigen PSI, Switzerland

The high brightness electron source for SwissFEL is an in-house built 2.6 cell normal-conducting RF gun which is scaled to the RF frequency of 2'998.8 MHz. The RF gun is capable of operating at 100 Hz repetition rate and produces electron bunches at the exit of the RF gun of an energy of 7 MeV. Key features of the RF gun are described and how they have been implemented in the manufacturing process. RF field measurements of the RF gun are presented to account for the mechanical precision reached after manufacturing. The RF gun has been thoroughly tested in the SwissFEL injector test facility.

THPP125

Super-Compact SLED System Used in the LCLS Diagnostic System

cavity, electron, klystron, impedance

1151

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

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

THPP127

The Status of the Construction of MICE Step IV

solenoid, emittance, experiment, cavity

1159

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

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

THPP140

High Transparent Matched Window for Standing Wave Linear Accelerators

linac, electron, vacuum, network

1192

A. Leggieri, F. Di Paolo, D. Passi
Università degli Studi di Roma "Tor Vergata", Roma, Italy
A. Ciccotelli, G. Felici
S.I.T., Aprilia, Italy

This paper proposes a particular Dielectric Window (DW) for Standing Wave (SW) Linear Accelerators (LINAC’s). This study investigates the in-frequency return loss behavior of the LINAC, in order to improve matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design is single-frequency based and considers the DW interface as an Input Matching Network (IMN) at the LINAC Normal Mode (NM) working frequency. Thus, design formulas are provided and Computer Aided Design (CAD) techniques are proposed. A prototype has been made and tested by performing cold S-parameter and Percentage Depth Dose (PDD) measurements of a LINAC with the proposed DW and with a traditional DW. The proposed device offers more energy transport attitude over the traditional DW, as shown by a return loss increase of 167% and an output electron energy increase of 5.5% while maintaining the same LINAC input power settings. This solution can offer a decrease of power line size, weight and cost. An after brazing global improvement of the accelerator figures of merit is also possible, as this study have demonstrated.
[1]Hiroyuki Arai, 1986
[2]K. Hirano, 1995
[3]Y. Otake, 1995
[5]A. Leggieri, 2014
[6]A. C. Ugural, 2003
[7]A. Leggieri, 2014
[8]F. Di Paolo, 2000
[9]N. Marcuvitz, 1951