LINAC2012 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
SUPB015	Production and Quality Control of the First Modules of the IFMIF-EVEDA RFQ	cavity, survey, controls, rfq	38
	F. Scantamburlo, R. Dima, A. Pepato INFN- Sez. di Padova, Padova, Italy C. Roncolato INFN/LNL, Legnaro (PD), Italy
	The IFMIF-EVEDA RFQ, designed to accelerate a 125 mA D⁺ beam from the initial energy of 0.1 MeV to the final energy of 5 MeV at the frequency of 175 MHz, consists of 18 mechanical modules whose length is approximately 54 cm each. The production of the modules has started and, in particular, the modules 16, 17, 15 and 11, plus the prototype modules 1 and 2 have undergone all the production steps, including precision milling and brazing. In this article, the progress of the production, and the quality control during the phases of the production of the modules will be described.

SUPB017	Tuning Studies on 4-rod-RFQs	rfq, simulation, linac, resonance	44
	J.S. Schmidt, B. Klump, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

SUPB022	First Measurements on the 325 MHz Superconducting CH Cavity	cavity, simulation, controls, linac	56
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany M. Pekeler RI Research Instruments GmbH, Bergisch Gladbach, Germany
	Funding: Work supported by HIM, GSI, BMBF Contr. No. 06FY161I At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

SUPB032	The C-band RF Pulse Compression for Soft XFEL at SINAP	cavity, simulation, klystron, free-electron-laser	83
	C.P. Wang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

SUPB035	RF Photoinjector and Radiating Structure for High-power THz Radiation Source	radiation, electron, vacuum, impedance	86
	S.M. Polozov, T.V. Bondarenko MEPhI, Moscow, Russia Y.A. Bashmakov LPI, Moscow, Russia
	Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

MOPLB05	Applications of Compact Dielectric-Based Accelerators	multipactoring, wakefield, impedance, electron	150
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, J.G. Power ANL, Argonne, USA
	Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPLB09	Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector	klystron, electron, controls, FEL	162
	R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro INFN/LNF, Frascati (Roma), Italy A. Mostacci, L. Palumbo URLS, Rome, Italy
	The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.
	Slides MOPLB09 [1.061 MB]

MOPB047	Applications of Compact Dielectric Based Accelerators	multipactoring, wakefield, impedance, electron	279
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, J.G. Power ANL, Argonne, USA
	Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPB049	Design of Compact C-Band Standing-Wave Accelerator for Medical Radiotherapy	electron, bunching, focusing, cavity	285
	H. Yang, M.-H. Cho, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea S.H. Kim ANL, Argonne, USA J.-S. Oh NFRI, Daejon, Republic of Korea
	Funding: Work supported by POSTECH Physics BK21 Program. We design a C-band standing-wave accelerator for an X-ray and electron source of medical radiotherapy. The accelerator system is operated two modes, using the X-ray and electron beams. Since two modes require different energy, the accelerator is capable of producing 6-MeV, 100-mA pulsed electron beams with peak 2-MW RF power, and 7.5-MeV, 50 mA electron beams with peak 2.5-MW RF power. The beam is focused by less than 1 mm without external magnets. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists of 3 bunching cells, 14 normal cells and a coupling cell. It is operated with the π/2-mode standing-wave. The bunching cells are designed to enhance the RF phase focusing. Each cavity is designed by the MWS code within 3% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics.

MOPB080	Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector	klystron, electron, controls, FEL	360
	R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro INFN/LNF, Frascati (Roma), Italy A. Mostacci, L. Palumbo URLS, Rome, Italy
	The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.

MOPB098	Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-Emittance Shaping	emittance, quadrupole, simulation, scattering	404
	C. Xiao, O.K. Kester IAP, Frankfurt am Main, Germany L. Groening GSI, Darmstadt, Germany
	The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the transverse rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances are changed by a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. Unlike emittance swapping the presented concept will allow transforming a beam of equal rms-emittances into a beam of different rms-emittances while preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. The actual work status towards the experimental demonstration of the concept at the GSI UNILAC is presented.

TUPLB01	The Swiss FEL RF Gun: RF Design and Thermal Analysis	gun, electron, cathode, linac	442
	J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer PSI, Villigen, Switzerland
	We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.
	Slides TUPLB01 [1.679 MB]

TUPB010	The Swiss FEL RF Gun: RF Design and Thermal Analysis	gun, electron, cathode, linac	495
	J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer PSI, Villigen, Switzerland
	We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

TUPB020	Status of the European XFEL 3.9 GHz system	cavity, HOM, status, cryomodule	519
	E. Vogel DESY, Hamburg, Germany A. Bosotti, P. Michelato, L. Monaco, C. Pagani, R. Paparella, P. Pierini, D. Sertore INFN/LASA, Segrate (MI), Italy E.R. Harms Fermilab, Batavia, USA
	The third harmonic system at 3.9 GHz of the European XFEL injector section will linearize the bunch RF curvature, induced by first accelerating module, before the first compression stage. This paper presents qualification tests on cavity prototypes and the on-going activities towards the realization of the third harmonic section of the European XFEL in view of its commissioning in 2014.

TUPB023	The Optimization of RF Deflector Input Power Coupler	emittance, electron, simulation, diagnostics	528
	A.Yu. Smirnov, O.A. Adonev, P.V. Binyukov, N.P. Sobenin MEPhI, Moscow, Russia
	This paper concerns the investigation of different types of input power cell for S-band RF electron deflector. This device serving for slice emittance diagnostics is a disc-loaded waveguide which operates with TE11-like wave in traveling wave regime with 120 deg phase shift per cell. Since this deflector meets the restriction on its length and has to provide high enough deflecting potential to a particle during its flight time it is significant to increase the transversal field strength in coupling cell or to shorten it so that the deflecting potential remains constant. The total structure consists of 14 regular cells and two couplers. As it is now all cells have the same length equal to D=33.34 mm and the field in couplers is lower than that of regular cells. In this paper different length are considered and numerically simulated in order to choose the best one.

TUPB048	Discussion of the Optimisation of a Linac Lattice to Minimise Disruption by a Class of Parasitic Modes	cavity, linac, simulation, lattice	585
	S. Molloy ESS, Lund, Sweden R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom
	It is well known that each resonant mode in the RF spectrum of multi-cell accelerating cavities will split into a passband containing a number of modes, and that the coupling of these modes to the beam is dependent on the velocity of the accelerated particles. If these modes are found to degrade the quality of the beam, it is possible to take various measures to damp them, and thus keep their effect below some critical threshold. In the case of the parasitic modes within the same passband as the fundamental accelerating mode, their frequency is typically too close to that of the fundamental to allow their power to be safely extracted, and so cavity designers must rely on the natural damping of the cavity itself. This note contains a theoretical discussion of the coupling of the beam to these passband modes for a large class of accelerating cavities, and provides a mathematical model for use during the design and optimisation of linacs.

TUPB071	First Measurements on the 325 MHz Superconducting CH Cavity	cavity, simulation, controls, linac	636
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany M. Pekeler RI Research Instruments GmbH, Bergisch Gladbach, Germany
	Funding: Work supported by GSI, BMBF Contr. No. 06FY7102, 06FY9089I At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

TUPB095	Design of Coupler for Direct Coupled Amplifier to Drift Tube Linac Cavities of the Injector RILAC2 for RIKEN RI Beam Factory	cavity, impedance, DTL, linac	684
	K. Suda, S. Arai, Y. Chiba, O. Kamigaito, M. Kase, H. Okuno, N. Sakamoto, Y. Watanabe, K. Yamada RIKEN Nishina Center, Wako, Japan
	A new linac RILAC2 was constructed at RIKEN RI Beam Factory as an injector for very heavy ions such as uranium and xenon of a high mass to charge ratio m/q ∼ 7, but high intensity ions can be extracted from an ion source. Three drift tube linac cavities, operate in continuous wave mode at 36.5 MHz, have been designed and built. In order to reduce an installation area, and to save a construction cost, we adopted a direct coupling method for a power amplifier without using a long transmission line. A complicated design procedure was performed in order to take into account a change of resonant frequency of the cavity caused by a capacitance of a power tube used in the amplifier. A design of the coupler, as well as the cavity was performed using a three-dimensional electromagnetic calculation code, CST Microwave Studio (MWS). The measured input impedance seen from the amplifier (700 – 1100 Ω) was reproduced well by the calculation of MWS. Also, in order to examine MWS, a case of a coupling with 50 Ω were calculated. The coupling conditions obtained by MWS were compared with the measurement and a calculation with a lumped circuit model.

TUPB097	The C-band RF Pulse Compression for Soft XFEL at SINAP	cavity, simulation, klystron, free-electron-laser	687
	C.P. Wang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

TUPB099	Input Coupler of the J-PARC DTL	DTL, vacuum, cavity, linac	690
	F. Naito, K. Nanmo, H. Tanaka KEK, Ibaraki, Japan K. Hirano, T. Ito JAEA/J-PARC, Tokai-mura, Japan
	Each tank of J-PARC DTL has two input couplers. The coupler has a movable coupling　loop with an capacitive element which increase the coupling with the tank. The loop position is the outside of the tank, where is the atmosphere. The tank vacuum is kept by the ceramic window on the wall for the coupler port. The ceramic is made of Aluminum oxide of 99.7 % purity. RF properties and the mechanical structure of the coupler were designed adequately in order to achieve the desired performance. We will report the design of the coupler in detail and the experiences for the practical operation of the DTL.

THPB008	A Coupled RFQ-IH Cavity for the Neutron Source FRANZ	rfq, cavity, DTL, simulation	858
	M. Heilmann, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz IAP, Frankfurt am Main, Germany
	The Frankfurt neutron source FRANZ will deliver neutrons in the energy range from 1 to 500 keV with high pulsed intensities. A 2 MeV proton beam will produce protons via the 7Li(p,n)7Be reaction. The 175 MHz accelerator cavity consists of a 4-rod-RFQ coupled with an 8 gap interdigital H-type drift tube section, the total cavity length being 2.3m. The combined cavity will be powered by one RF amplifier to reduce investment and operation costs. The inductive power coupler will be at the RFQ part. The coupling into the IH - section is provided through a large aperture - mainly inductively. By CST - MWS - simulations as well as by an RF - model the voltage tuning along the cavity was investigated, and with special care the balance between both cavity sections. A first set of RFQ electrodes should allow to reach beam currents up to 50 mA in cw operation: The beam is pulsed with 100 ns, 250 kHz, while the cavity has to be operated cw due to the high rep. rate. The layout of the cavity cooling aims on a maximum accessible heat load of 200 kW.

THPB012	High Resolution Emittance Measurements at SNS Front End	emittance, linac, DTL, target	870
	A.P. Zhukov, A.V. Aleksandrov ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. Spallation Neutron Source (SNS) linac accelerates an H⁻ beam from 2.5MeV up to 1GeV. Recently the emittance scanner in the MEBT (2.5 MeV) was upgraded. In addition to the slit - harp measurement we now can use a slit installed on the same actuator as the harp. In combination with a faraday cup located downstream in DTL part of the linac it represents a classical slit-slit emittance measurement device. While a slit – slit scan takes much longer time, it is immune to harp related problems such as wire cross talk and thus looks promising for accurate halo measurements. Time resolution of the new device seems to be sufficient to estimate amount of the beam in the chopper gap (the scanner is downstream of the chopper) and probably measure its emittance. The paper describes initial measurements with new device and some model validation data.

THPB020	Annular-ring Coupled Structure for the Energy Upgrade of the J-PARC Linac	linac, vacuum, cavity, target	888
	H. Ao, H. Asano, N. Ouchi, J. Tamura JAEA/J-PARC, Tokai-mura, Japan F. Naito, K. Takata KEK, Ibaraki, Japan
	The linac of Japan Proton Accelerator Research Complex (J-PARC), which is an injector to the synchrotron, comprises a 3-MeV RFQ, 50-MeV DTLs and the 181-MeV Separated-type DTLs. In order to increase the beam power of the synchrotron, the task of the 400-MeV energy upgrade of the linac started from March 2009. The tanks of the Annular-ring Coupled Structure (ACS) linac, RF sources, beam monitors and utilities are in production. Although some peripheral components of the ACS linac are prepared previously, the all ACS tanks will be installed and conditioned for 4 months from July 2013. Beam commissioning of the 400-MeV linac is scheduled to begin in October and expected to finish at the end of November 2013. In this paper, we present the current status of the energy upgrade and some R&D results for new equipment for ACS linac.

THPB031	Status Report on the French High-intensity Proton Injector Project at SACLAY (IPHI)	dipole, rfq, quadrupole, diagnostics	921
	B. Pottin, M. Desmons, A. France, R. Gobin, O. Piquet CEA/DSM/IRFU, France
	The construction of IPHI (High Power Proton Accelerator) is in its final step of installation. The high intensity light ion source (SILHI) has been built first to produce regularly CW high intensity (over 100 mA) proton beams. The low energy front end of IPHI is based on a 352 MHz, 6 m long Radiofrequency Quadrupole (RFQ) cavity. The RFQ will accelerate beam up to 100 mA with energy up to 3 MeV. A diagnostics line has been designed to measure all the main characteristics of the beam at the RFQ output. In this paper we will present the status for the main components of the injector, in particularly the RFQ fabrication and the RF power facilities.

THPB042	Production and Quality Control of the First Modules of the IFMIF-EVEDA RFQ	cavity, survey, controls, rfq	948
	F. Scantamburlo, R. Dima, A. Pepato INFN- Sez. di Padova, Padova, Italy C. Roncolato INFN/LNL, Legnaro (PD), Italy
	The IFMIF/EVEDA RFQ, designed to accelerate a 125mA D⁺ beam from 0.1 MeV to 5 MeV at a frequency of 175 MHz, consists of 18 modules with length of ~550 mm each. The production of the modules has been started and 2 prototype modules plus module 16 have undergone all the production steps, including precision milling and brazing. The progress of the construction and especially the fine tuning of the design and engineering phase are reported.

THPB049	Tuning Studies on 4-Rod-RFQs	rfq, simulation, linac, resonance	963
	J.S. Schmidt, B. Klump, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

THPB073	Initial RF Tests of the Diamond S-Band Photocathode Gun	gun, cathode, cavity, controls	1002
	C. Christou, S.A. Pande Diamond, Oxfordshire, United Kingdom
	An S-band photocathode electron gun designed to operate at repetition rates up to 1 kHz CW has been designed at Diamond and manufactured at FMB. The first test results of this gun are presented. Low-power RF measurements have been carried out to verify the RF design of the gun, and high-power conditioning and RF test has begun. Initial high power tests have been carried out at 5 Hz repetition rate using the S-band RF plant normally used to power the Diamond linac: the benefits and limitations of this approach are considered, together with plans for further testing. J. H. Han et al, NIM A 647(2011) 17-24

THPB074	RF Photoinjector and Radiating Structure for High-power THz Radiation Source	radiation, electron, vacuum, impedance	1005
	S.M. Polozov, T.V. Bondarenko MEPhI, Moscow, Russia Y.A. Bashmakov LPI, Moscow, Russia
	Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

Paper

Title

Other Keywords

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SUPB015

Production and Quality Control of the First Modules of the IFMIF-EVEDA RFQ

cavity, survey, controls, rfq

38

F. Scantamburlo, R. Dima, A. Pepato
INFN- Sez. di Padova, Padova, Italy
C. Roncolato
INFN/LNL, Legnaro (PD), Italy

The IFMIF-EVEDA RFQ, designed to accelerate a 125 mA D⁺ beam from the initial energy of 0.1 MeV to the final energy of 5 MeV at the frequency of 175 MHz, consists of 18 mechanical modules whose length is approximately 54 cm each. The production of the modules has started and, in particular, the modules 16, 17, 15 and 11, plus the prototype modules 1 and 2 have undergone all the production steps, including precision milling and brazing. In this article, the progress of the production, and the quality control during the phases of the production of the modules will be described.

SUPB017

Tuning Studies on 4-rod-RFQs

rfq, simulation, linac, resonance

44

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

A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

SUPB022

First Measurements on the 325 MHz Superconducting CH Cavity

cavity, simulation, controls, linac

56

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Pekeler
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Funding: Work supported by HIM, GSI, BMBF Contr. No. 06FY161I
At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

SUPB032

The C-band RF Pulse Compression for Soft XFEL at SINAP

cavity, simulation, klystron, free-electron-laser

83

C.P. Wang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

SUPB035

RF Photoinjector and Radiating Structure for High-power THz Radiation Source

radiation, electron, vacuum, impedance

86

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia
Y.A. Bashmakov
LPI, Moscow, Russia

Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

MOPLB05

Applications of Compact Dielectric-Based Accelerators

multipactoring, wakefield, impedance, electron

150

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPLB09

Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector

klystron, electron, controls, FEL

162

R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro
INFN/LNF, Frascati (Roma), Italy
A. Mostacci, L. Palumbo
URLS, Rome, Italy

The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.

Slides MOPLB09 [1.061 MB]

MOPB047

Applications of Compact Dielectric Based Accelerators

multipactoring, wakefield, impedance, electron

279

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPB049

Design of Compact C-Band Standing-Wave Accelerator for Medical Radiotherapy

electron, bunching, focusing, cavity

285

H. Yang, M.-H. Cho, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Kim
ANL, Argonne, USA
J.-S. Oh
NFRI, Daejon, Republic of Korea

Funding: Work supported by POSTECH Physics BK21 Program.
We design a C-band standing-wave accelerator for an X-ray and electron source of medical radiotherapy. The accelerator system is operated two modes, using the X-ray and electron beams. Since two modes require different energy, the accelerator is capable of producing 6-MeV, 100-mA pulsed electron beams with peak 2-MW RF power, and 7.5-MeV, 50 mA electron beams with peak 2.5-MW RF power. The beam is focused by less than 1 mm without external magnets. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists of 3 bunching cells, 14 normal cells and a coupling cell. It is operated with the π/2-mode standing-wave. The bunching cells are designed to enhance the RF phase focusing. Each cavity is designed by the MWS code within 3% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics.

MOPB080

Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector

klystron, electron, controls, FEL

360

R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro
INFN/LNF, Frascati (Roma), Italy
A. Mostacci, L. Palumbo
URLS, Rome, Italy

The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.

MOPB098

Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-Emittance Shaping

emittance, quadrupole, simulation, scattering

404

C. Xiao, O.K. Kester
IAP, Frankfurt am Main, Germany
L. Groening
GSI, Darmstadt, Germany

The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the transverse rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances are changed by a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. Unlike emittance swapping the presented concept will allow transforming a beam of equal rms-emittances into a beam of different rms-emittances while preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. The actual work status towards the experimental demonstration of the concept at the GSI UNILAC is presented.

TUPLB01

The Swiss FEL RF Gun: RF Design and Thermal Analysis

gun, electron, cathode, linac

442

J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer
PSI, Villigen, Switzerland

We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

Slides TUPLB01 [1.679 MB]

TUPB010

The Swiss FEL RF Gun: RF Design and Thermal Analysis

gun, electron, cathode, linac

495

J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer
PSI, Villigen, Switzerland

We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

TUPB020

Status of the European XFEL 3.9 GHz system

cavity, HOM, status, cryomodule

519

E. Vogel
DESY, Hamburg, Germany
A. Bosotti, P. Michelato, L. Monaco, C. Pagani, R. Paparella, P. Pierini, D. Sertore
INFN/LASA, Segrate (MI), Italy
E.R. Harms
Fermilab, Batavia, USA

The third harmonic system at 3.9 GHz of the European XFEL injector section will linearize the bunch RF curvature, induced by first accelerating module, before the first compression stage. This paper presents qualification tests on cavity prototypes and the on-going activities towards the realization of the third harmonic section of the European XFEL in view of its commissioning in 2014.

TUPB023

The Optimization of RF Deflector Input Power Coupler

emittance, electron, simulation, diagnostics

528

A.Yu. Smirnov, O.A. Adonev, P.V. Binyukov, N.P. Sobenin
MEPhI, Moscow, Russia

This paper concerns the investigation of different types of input power cell for S-band RF electron deflector. This device serving for slice emittance diagnostics is a disc-loaded waveguide which operates with TE11-like wave in traveling wave regime with 120 deg phase shift per cell. Since this deflector meets the restriction on its length and has to provide high enough deflecting potential to a particle during its flight time it is significant to increase the transversal field strength in coupling cell or to shorten it so that the deflecting potential remains constant. The total structure consists of 14 regular cells and two couplers. As it is now all cells have the same length equal to D=33.34 mm and the field in couplers is lower than that of regular cells. In this paper different length are considered and numerically simulated in order to choose the best one.

TUPB048

Discussion of the Optimisation of a Linac Lattice to Minimise Disruption by a Class of Parasitic Modes

cavity, linac, simulation, lattice

585

S. Molloy
ESS, Lund, Sweden
R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom

It is well known that each resonant mode in the RF spectrum of multi-cell accelerating cavities will split into a passband containing a number of modes, and that the coupling of these modes to the beam is dependent on the velocity of the accelerated particles. If these modes are found to degrade the quality of the beam, it is possible to take various measures to damp them, and thus keep their effect below some critical threshold. In the case of the parasitic modes within the same passband as the fundamental accelerating mode, their frequency is typically too close to that of the fundamental to allow their power to be safely extracted, and so cavity designers must rely on the natural damping of the cavity itself. This note contains a theoretical discussion of the coupling of the beam to these passband modes for a large class of accelerating cavities, and provides a mathematical model for use during the design and optimisation of linacs.

TUPB071

First Measurements on the 325 MHz Superconducting CH Cavity

cavity, simulation, controls, linac

636

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Pekeler
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Funding: Work supported by GSI, BMBF Contr. No. 06FY7102, 06FY9089I
At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

TUPB095

Design of Coupler for Direct Coupled Amplifier to Drift Tube Linac Cavities of the Injector RILAC2 for RIKEN RI Beam Factory

cavity, impedance, DTL, linac

684

K. Suda, S. Arai, Y. Chiba, O. Kamigaito, M. Kase, H. Okuno, N. Sakamoto, Y. Watanabe, K. Yamada
RIKEN Nishina Center, Wako, Japan

A new linac RILAC2 was constructed at RIKEN RI Beam Factory as an injector for very heavy ions such as uranium and xenon of a high mass to charge ratio m/q ∼ 7, but high intensity ions can be extracted from an ion source. Three drift tube linac cavities, operate in continuous wave mode at 36.5 MHz, have been designed and built. In order to reduce an installation area, and to save a construction cost, we adopted a direct coupling method for a power amplifier without using a long transmission line. A complicated design procedure was performed in order to take into account a change of resonant frequency of the cavity caused by a capacitance of a power tube used in the amplifier. A design of the coupler, as well as the cavity was performed using a three-dimensional electromagnetic calculation code, CST Microwave Studio (MWS). The measured input impedance seen from the amplifier (700 – 1100 Ω) was reproduced well by the calculation of MWS. Also, in order to examine MWS, a case of a coupling with 50 Ω were calculated. The coupling conditions obtained by MWS were compared with the measurement and a calculation with a lumped circuit model.

TUPB097

The C-band RF Pulse Compression for Soft XFEL at SINAP

cavity, simulation, klystron, free-electron-laser

687

C.P. Wang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

TUPB099

Input Coupler of the J-PARC DTL

DTL, vacuum, cavity, linac

690

F. Naito, K. Nanmo, H. Tanaka
KEK, Ibaraki, Japan
K. Hirano, T. Ito
JAEA/J-PARC, Tokai-mura, Japan

Each tank of J-PARC DTL has two input couplers. The coupler has a movable coupling　loop with an capacitive element which increase the coupling with the tank. The loop position is the outside of the tank, where is the atmosphere. The tank vacuum is kept by the ceramic window on the wall for the coupler port. The ceramic is made of Aluminum oxide of 99.7 % purity. RF properties and the mechanical structure of the coupler were designed adequately in order to achieve the desired performance. We will report the design of the coupler in detail and the experiences for the practical operation of the DTL.

THPB008

A Coupled RFQ-IH Cavity for the Neutron Source FRANZ

rfq, cavity, DTL, simulation

858

M. Heilmann, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz
IAP, Frankfurt am Main, Germany

The Frankfurt neutron source FRANZ will deliver neutrons in the energy range from 1 to 500 keV with high pulsed intensities. A 2 MeV proton beam will produce protons via the 7Li(p,n)7Be reaction. The 175 MHz accelerator cavity consists of a 4-rod-RFQ coupled with an 8 gap interdigital H-type drift tube section, the total cavity length being 2.3m. The combined cavity will be powered by one RF amplifier to reduce investment and operation costs. The inductive power coupler will be at the RFQ part. The coupling into the IH - section is provided through a large aperture - mainly inductively. By CST - MWS - simulations as well as by an RF - model the voltage tuning along the cavity was investigated, and with special care the balance between both cavity sections. A first set of RFQ electrodes should allow to reach beam currents up to 50 mA in cw operation: The beam is pulsed with 100 ns, 250 kHz, while the cavity has to be operated cw due to the high rep. rate. The layout of the cavity cooling aims on a maximum accessible heat load of 200 kW.

THPB012

High Resolution Emittance Measurements at SNS Front End

emittance, linac, DTL, target

870

A.P. Zhukov, A.V. Aleksandrov
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
Spallation Neutron Source (SNS) linac accelerates an H⁻ beam from 2.5MeV up to 1GeV. Recently the emittance scanner in the MEBT (2.5 MeV) was upgraded. In addition to the slit - harp measurement we now can use a slit installed on the same actuator as the harp. In combination with a faraday cup located downstream in DTL part of the linac it represents a classical slit-slit emittance measurement device. While a slit – slit scan takes much longer time, it is immune to harp related problems such as wire cross talk and thus looks promising for accurate halo measurements. Time resolution of the new device seems to be sufficient to estimate amount of the beam in the chopper gap (the scanner is downstream of the chopper) and probably measure its emittance. The paper describes initial measurements with new device and some model validation data.

THPB020

Annular-ring Coupled Structure for the Energy Upgrade of the J-PARC Linac

linac, vacuum, cavity, target

888

H. Ao, H. Asano, N. Ouchi, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
F. Naito, K. Takata
KEK, Ibaraki, Japan

The linac of Japan Proton Accelerator Research Complex (J-PARC), which is an injector to the synchrotron, comprises a 3-MeV RFQ, 50-MeV DTLs and the 181-MeV Separated-type DTLs. In order to increase the beam power of the synchrotron, the task of the 400-MeV energy upgrade of the linac started from March 2009. The tanks of the Annular-ring Coupled Structure (ACS) linac, RF sources, beam monitors and utilities are in production. Although some peripheral components of the ACS linac are prepared previously, the all ACS tanks will be installed and conditioned for 4 months from July 2013. Beam commissioning of the 400-MeV linac is scheduled to begin in October and expected to finish at the end of November 2013. In this paper, we present the current status of the energy upgrade and some R&D results for new equipment for ACS linac.

THPB031

Status Report on the French High-intensity Proton Injector Project at SACLAY (IPHI)

dipole, rfq, quadrupole, diagnostics

921

B. Pottin, M. Desmons, A. France, R. Gobin, O. Piquet
CEA/DSM/IRFU, France

The construction of IPHI (High Power Proton Accelerator) is in its final step of installation. The high intensity light ion source (SILHI) has been built first to produce regularly CW high intensity (over 100 mA) proton beams. The low energy front end of IPHI is based on a 352 MHz, 6 m long Radiofrequency Quadrupole (RFQ) cavity. The RFQ will accelerate beam up to 100 mA with energy up to 3 MeV. A diagnostics line has been designed to measure all the main characteristics of the beam at the RFQ output. In this paper we will present the status for the main components of the injector, in particularly the RFQ fabrication and the RF power facilities.

THPB042

Production and Quality Control of the First Modules of the IFMIF-EVEDA RFQ

cavity, survey, controls, rfq

948

F. Scantamburlo, R. Dima, A. Pepato
INFN- Sez. di Padova, Padova, Italy
C. Roncolato
INFN/LNL, Legnaro (PD), Italy

The IFMIF/EVEDA RFQ, designed to accelerate a 125mA D⁺ beam from 0.1 MeV to 5 MeV at a frequency of 175 MHz, consists of 18 modules with length of ~550 mm each. The production of the modules has been started and 2 prototype modules plus module 16 have undergone all the production steps, including precision milling and brazing. The progress of the construction and especially the fine tuning of the design and engineering phase are reported.

THPB049

Tuning Studies on 4-Rod-RFQs

rfq, simulation, linac, resonance

963

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

A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

THPB073

Initial RF Tests of the Diamond S-Band Photocathode Gun

gun, cathode, cavity, controls

1002

C. Christou, S.A. Pande
Diamond, Oxfordshire, United Kingdom

An S-band photocathode electron gun designed to operate at repetition rates up to 1 kHz CW has been designed at Diamond and manufactured at FMB*. The first test results of this gun are presented. Low-power RF measurements have been carried out to verify the RF design of the gun, and high-power conditioning and RF test has begun. Initial high power tests have been carried out at 5 Hz repetition rate using the S-band RF plant normally used to power the Diamond linac: the benefits and limitations of this approach are considered, together with plans for further testing.
* J. H. Han et al, NIM A 647(2011) 17-24

THPB074

RF Photoinjector and Radiating Structure for High-power THz Radiation Source

radiation, electron, vacuum, impedance

1005

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia
Y.A. Bashmakov
LPI, Moscow, Russia

Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.