02 Proton and Ion Accelerators and Applications
2C RFQs

Paper	Title	Page
SUPB014	RF Setup of the MedAustron RFQ	35
	B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany J. Haeuser Kress GmbH, Biebergemuend, Germany
	A Radio Frequency Quadrupole (RFQ) was built for the injector of the cancer treatment facility MedAuston in Austria. For the RF design simulations were performed using CST Microwave Studio and the structure was manufactured by Firma Kress in Biebergemuend, Germany. The simulations and the RF setup of the delivered RFQ are presented in this paper.
SUPB015	Production and Quality Control of the First Modules of the IFMIF-EVEDA 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.
SUPB016	RFQ With Improved Energy Gain	41
	A. Kolomiets ITEP, Moscow, Russia A.S. Plastun MEPhI, Moscow, Russia
	RFQ structure is practically only one choice for using in front ends of ion linacs for acceleration up to energy about 3 MeV. This limit is due to its relatively low acceleration efficiency. However it isn’t intrinsic feature of RFQ principle. It is defined only by vane geometry of conventional RFQ structure with sinusoidal modulation of vanes. The paper presents results of analysis RFQ with modified vane geometries that allow to improve acceleration efficiency. RFQ with modified vanes was used for design second section of heavy ion injector of TWAC for acceleration of ions with Z/A = 0.33 up to 7 MeV/u.
SUPB017	Tuning Studies on 4-rod-RFQs	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.
THPLB06	The New Option for a Front End of Ion Linac	822
	A.D. Kovalenko JINR, Dubna, Moscow Region, Russia A. Kolomiets ITEP, Moscow, Russia
	The standard ion linac front-end consisting of RFQ, two tanks of accelerating IH-structures, MEBTs with matching and focusing elements is modified to achieve better performances. Special vane section that provides the same beam transformation as debuncher and quadrupole triplet is added within the RFQ tank, whereas superconducting focusing elements, solenoids, for example, are used between the IH - structure tanks. Test frond end was designed to provide the output beam energy up to 4 MeV/u for the particles with charge-to-mass ratio of 0.16 < q/m ≤ 1. Results of beam dynamics simulation are presented. Possible application of the considered scheme for the NICA facility at JINR (Dubna, Russia) is discussed.
	Slides THPLB06 [0.482 MB]
THPLB07	Experience with a 4-Rod CW Radio Frequency Quadrupole	825
	P. Gerhard, W.A. Barth, L.A. Dahl, W. Hartmann, G. Schreiber, W. Vinzenz, H. Vormann GSI, Darmstadt, Germany
	Since 1991 the High Charge State Injector (HLI) provides heavy ion beams for the linear accelerator UNILAC at GSI*. It is equipped with an ECR ion source and an RFQ-IH linac which accelerates highly charged ion beams with high duty factor of up to 30% to 1.4 MeV/u for further acceleration in the Alvarez DTL of the UNILAC. Main user of these beams is the Super Heavy Element (SHE) research, one of the outstanding projects at GSI**. Experiments like TASCA and SHIP strongly benefit from the high average beam intensities. After two decades of successful operation the four-rod Radio Frequency Quadrupole (RFQ) accelerator was replaced in 2010 by a newly designed RFQ of the same type**. Besides higher beam transmission, the principal intention of this upgrade was to raise the duty factor up to 100%, since the HLI is foreseen as injector for the upcoming cw linac dedicated to the SHE program**. Commissioning and operational experience from the first years revealed that this goal could not be reached easily. In this paper we present the RFQ design, commissioning results, operational experience and future activities. * N. Angert et al., EPAC92, Berlin, Germany (1992), p. 167 ** L. Dahl et al., LINAC10, Tsukuba, Japan (2010), MOP042, and references therein
	Slides THPLB07 [0.986 MB]
THPLB08	High-Power RF Conditioning of the TRASCO RFQ	828
	E. Fagotti, L. Antoniazzi, F. Grespan, A. Palmieri INFN/LNL, Legnaro (PD), Italy M. Desmons CEA/DSM/IRFU, France
	The TRASCO RFQ is designed to accelerate a 40 mA proton beam up to 5 MeV. It is a CW machine which has to show stable operation and provide the requested availability. It is composed of three electromagnetic segment coupled via two coupling cells. Each segment is divided into two 1.2 m long OFE copper modules. The RFQ is fed through eight loop-based power couplers to deliver RF to the cavity from a 352.2 MHZ, 1.3 MW klystron. After couplers conditioning, the first electromagnetic segment was successfully tested at full power. RFQ cavity reached the nominal 68 kV inter-vane voltage (1.8 Kilp.) in CW operation. Moreover, during conditioning in pulsed operation, it was possible to reach 83 kV inter-vane voltage (2.2 Kilp.) with a 1% duty cycle. The description of the experimental setup and procedure, as well as the main results of the conditioning procedure will be reported in this paper.
	Slides THPLB08 [1.384 MB]
THPB035	Experience with a 4-Rod CW Radio Frequency Quadrupole	930
	P. Gerhard, W.A. Barth, L.A. Dahl, W. Hartmann, G. Schreiber, W. Vinzenz, H. Vormann GSI, Darmstadt, Germany
	Since 1991 the High Charge State Injector (HLI) provides heavy ion beams for the linear accelerator UNILAC at GSI*. It is equipped with an ECR ion source and an RFQ-IH linac which accelerates highly charged ion beams with high duty factor of up to 30% to 1.4 MeV/u for further acceleration in the Alvarez DTL of the UNILAC. Main user of these beams is the Super Heavy Element (SHE) research, one of the outstanding projects at GSI**. Experiments like TASCA and SHIP strongly benefit from the high average beam intensities. After two decades of successful operation the four-rod Radio Frequency Quadrupole (RFQ) accelerator was replaced in 2010 by a newly designed RFQ of the same type**. Besides higher beam transmission, the principal intention of this upgrade was to raise the duty factor up to 100%, since the HLI is foreseen as injector for the upcoming cw linac dedicated to the SHE program**. Commissioning and operational experience from the first years revealed that this goal could not be reached easily. In this paper we present the RFQ design, commissioning results, operational experience and future activities. * N. Angert et al., EPAC92, Berlin, Germany (1992), p. 167 ** L. Dahl et al., LINAC10, Tsukuba, Japan (2010), MOP042, and references therein
THPB036	The New Option for a Front End of Ion Linac	933
	A.D. Kovalenko JINR, Dubna, Moscow Region, Russia A. Kolomiets ITEP, Moscow, Russia
	The standard ion linac front-end consisting of RFQ, two tanks of accelerating IH-structures, MEBTs with matching and focusing elements is modified to achieve better performances. Special vane section that provides the same beam transformation as debuncher and quadrupole triplet is added within the RFQ tank, whereas superconducting focusing elements, solenoids, for example, are used between the IH - structure tanks. Test frond end was designed to provide the output beam energy up to 4 MeV/u for the particles with charge-to-mass ratio of 0.16 < q/m ≤ 1. Results of beam dynamics simulation are presented. Possible application of the considered scheme for the NICA facility at JINR (Dubna, Russia) is discussed.
THPB037	Iron Beam Acceleration with DPIS	936
	M. Okamura BNL, Upton, Long Island, New York, USA P.J. Jandovitz Cornell University, Ithaca, New York, USA T. Kanesue IAP, Frankfurt am Main, Germany M. Sekine RLNR, Tokyo, Japan T. Yamamoto RISE, Tokyo, Japan
	Funding: The work supported by US. DOE and RIKEN Japan. It has been proved that direct plasma Injection Scheme (DPIS) is an efficient way to accelerate high current highly charged state heavy ion beam. More than 50 mA (peak current) of various heavy ion beams can be easily accelerated. However, it was rather difficult to obtain longer pulse especially for highly charged particles. To induce highly charged states ions, a high plasma temperature is required at the laser irradiation point and the high temperature automatically gives a very fast expansion velocity of the plasma. This shortens the ion beam pulse length. To compensate the shorter ion pulse length, we can extend the plasma drift length, but it will dilute the brightness of the plasma since the plasma expands three dimensionally. To avoid the reduction of the brightness, a simple long solenoid was applied to confine the diverging angle of the plasma expansion. In the conference, this new technique will be explained and the latest results of iron beam acceleration will be shown.
THPB038	Assembly and RF Tuning of the Linac4 RFQ at CERN	939
	C. Rossi, A. Dallocchio, J. Hansen, J.-B. Lallement, A.M. Lombardi, S.J. Mathot, D. Pugnat, M.A. Timmins, G. Vandoni, M. Vretenar CERN, Geneva, Switzerland M. Desmons, A. France, Y. Le Noa, J. Novo, O. Piquet CEA/DSM/IRFU, France
	The fabrication of Linac4 is progressing at CERN with the goal of making a 160 MeV H− beam available to the LHC injection chain as from 2015. In the Linac4 the first stage of beam acceleration, after its extraction from the ion source, is provided by a Radiofrequency Quadrupole accelerator (RFQ), operating at the RF frequency of 352.2 MHz and which accelerates the ion beam to the energy of 3 MeV. The RFQ, made of three modules, one meter each, is of the four-vane kind, has been designed in the frame of a collaboration between CERN and CEA and has been completely machined and assembled at CERN. The paper describes the assembly of the RFQ structure and reports the results of RF low power measurements, in order to achieve the required accelerating field flatness within 1% of the nominal field profile.
THPB039	Design of a Four-Vane RFQ for China ADS Project	942
	Z.L. Zhang, X. Du, Y. He, X. Jin, C. Li, Y. Liu, A. Shi, L.P. Sun, B. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China M.D. Hoff, A.R. Lambert, D. Li, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA J. Wang Lanzhou University of Technology, People's Republic of China C. Zhang IAP, Frankfurt am Main, Germany
	A four-vane RFQ accelerator has been designed for the ADS project which has been launched in China since 2011. As one of the front ends of C-ADS LINAC, the RFQ works at a frequency of 162.5 MHz, accelerating the proton beam from 35 keV to 2.1 MeV. Due to the CW (continuous wave) operating mode, a small Kilpatric factor of 1.2 was adopted. At the same time, Pi-mode rods are employed to reduce the effect of dipole mode on quadrupole mode, and cavity tuning will be implemented by temperature adjustment of cooling water. Beam dynamics design, RF cavity design, thermal and stress analysis all will be presented in the paper.
THPB040	High-Power RF Conditioning of the TRASCO RFQ	945
	E. Fagotti, L. Antoniazzi, F. Grespan, A. Palmieri INFN/LNL, Legnaro (PD), Italy M. Desmons CEA/DSM/IRFU, France
	The TRASCO RFQ is designed to accelerate a 40 mA proton beam up to 5 MeV. It is a CW machine which has to show stable operation and provide the requested availability. It is composed of three electromagnetic segment coupled via two coupling cells. Each segment is divided into two 1.2 m long OFE copper modules. The RFQ is fed through eight loop-based power couplers to deliver RF to the cavity from a 352.2 MHZ, 1.3 MW klystron. After couplers conditioning, the first electromagnetic segment was successfully tested at full power. RFQ cavity reached the nominal 68 kV inter-vane voltage (1.8 Kilp.) in CW operation. Moreover, during conditioning in pulsed operation, it was possible to reach 83 kV inter-vane voltage (2.2 Kilp.) with a 1% duty cycle. The description of the experimental setup and procedure, as well as the main results of the conditioning procedure will be reported in this paper.
THPB042	Production and Quality Control of the First Modules of the IFMIF-EVEDA 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.
THPB043	The RFQ injector for the Radioactive Ion Beam of SPES Project	951
	M. Comunian, F. Grespan, A. Palmieri, A. Pisent INFN/LNL, Legnaro (PD), Italy
	A Continous Wave Radio Frequency Quadrupole Accelerator has been designed for the Radioactive Ion Beam of SPES Project to be used as an Injector of the ALPI Linac. The RFQ frequency is 80 MHz for an input energy of 40 keV, with output energy of 5 MeV and ion ratio q/A<= 1/7. Particular care has been put in the design phase to include an internal bunching section able to reduce the longitudinal output emittance. The details of the RF study of such a cavity are included as well.
THPB044	Plans for an Integrated Front-End Test Stand at the Spallation Neutron Source	954
	M.S. Champion, A.V. Aleksandrov, M.T. Crofford, D. Heidenreich, Y.W. Kang, J. Moss, R.T. Roseberry, J.P. Schubert ORNL, Oak Ridge, Tennessee, USA
	Funding: Work performed at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. A spare Radio-Frequency Quadrupole (RFQ) is presently being fabricated by industry with delivery to Oak Ridge National Laboratory planned in late 2012. The establishment of a test stand at the Spallation Neutron Source site is underway so that complete acceptance testing can be performed during the winter of 2012-2013. This activity is the first step in the establishment of an integrated front-end test stand that will include an ion source, low-energy beam transport (LEBT), RFQ, medium-energy beam transport, diagnostics, and a beam dump. The test stand will be capable of delivering an H− ion beam of up to 50 mA with a pulse length of 1 ms and a repetition rate of 60 Hz or a proton beam of up to 50 mA, 100 μs, 1 Hz. The test stand will enable the following activities: complete ion source characterization; development of a magnetic LEBT chopper; development of a two-source layout; development of beam diagnostics; and study of beam dynamics of high intensity beam.
THPB046	RF Setup of the MedAustron RFQ	957
	B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany J. Haeuser Kress GmbH, Biebergemuend, Germany
	A Radio Frequency Quadrupole (RFQ) was built for the injector of the cancer treatment facility MedAuston in Austria. For the RF design simulations were performed using CST Microwave Studio and the structure was manufactured by Firma Kress in Biebergemuend, Germany. The simulations and the RF setup of the delivered RFQ are presented in this paper.
THPB047	Test RFQ for the MAX Project	960
	M. Vossberg, H. Klein, H. Podlech, A. Schempp, C. Zhang IAP, Frankfurt am Main, Germany A. Bechtold NTG Neue Technologien GmbH & Co KG, Gelnhausen, Germany
	As a part of the MAX project it will be demonstrated by simulations and thermal measurements, that a 4-rod-RFQ is the right choice even at cw-operation. A 4-rod Test-RFQ with a resonance frequency of 175 MHz has been designed and built for the MAX-Project. But the RFQ had to be modified to solve the cooling problem at cw-operation, the geometrical precision had to be improved as well as the rf-contacts. The developments led to a new layout and a sophisticated production procedure of the stems and the electrodes. Calculations show an improved Rp-value leading to powerlosses of ca. 25 kW/m only, which is about half of the powerlosses which could be achieved safely at cw-operation of the similar Saraf-RFQ. Thermal measurements and simulations with the single components are in progress. The temperature distribution in cw-operation will be measured and the rf-performance checked.
THPB049	Tuning Studies on 4-Rod-RFQs	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.
THPB050	RFQ With Improved Energy Gain	966
	A. Kolomiets ITEP, Moscow, Russia A.S. Plastun MEPhI, Moscow, Russia
	RFQ structure is practically only one choice for using in front ends of ion linacs for acceleration up to energy about 3 MeV. This limit is due to its relatively low acceleration efficiency. However it isn’t intrinsic feature of RFQ principle. It is defined only by vane geometry of conventional RFQ structure with sinusoidal modulation of vanes. The paper presents results of analysis RFQ with modified vane geometries that allow to improve acceleration efficiency. RFQ with modified vanes was used for design second section of heavy ion injector of TWAC for acceleration of ions with Z/A = 0.33 up to 7 MeV/u.
THPB051	Improvements at the BNL 200 MeV Linac	969
	D. Raparia, J.G. Alessi, B. Briscoe, J.M. Fite, O. Gould, V. LoDestro, M. Okamura, J. Ritter, A. Zelenski BNL, Upton, Long Island, New York, USA
	After reconfiguration of the low energy (35 keV) and the medium energy (750 keV) transport lines in 2009-10, the Brookhaven linac delivered the highest intensity beam since it was built in 1970 (~120 μA average current of H− to the Brookhaven Linac Isotope Producer). It also delivered lower emittance polarized H− ion beam for the polarized program at RHIC. To increase the intensity further, the match into the RFQ was improved by reducing the distance from the fnal focusing solenoid to the RFQ and replacing the buncher in the 750 keV line with one with higher Q value, to allow operation at higher power. We also found that drift –tube linac tank number 7 was operating with about 1 MW lower power than design. The transmission efficiencies and beam quality will be discussed in the paper.
THPB052	Recent Progress with the J-PARC RFQs	972
	Y. Kondo, K. Hasegawa, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Kawamata, F. Naito, T. Sugimura KEK, Ibaraki, Japan
	In this paper, we will report recent topics about J-PARC RFQs. First, the operating RFQ (RFQ I) have been recovered from the long shutdown due to the earthquake. This RFQ have been suffered from breakdown problem since 2008, therefore we have been developing a back-up RFQ (RFQ II). In April 2012, the high power test was successfully performed. Finally, we are fabricating a new RFQ for the beam-current upgrade of the J-PARC linac (RFQ III). The status of these RFQs are described.
THPB055	Numerical Simulations of ProjectX/PXIE RFQ	975
	J.-F. Ostiguy, A. Saini, N. Solyak Fermilab, Batavia, USA
	Funding: Fermi Research Alliance, LLC under DOE Contract No. De-AC02-07CH11359 Project-X is a proposed superconducting linac-based high intensity proton source at Fermilab. The machine first stages operate in CW mode from 2.1 to 3 GeV and a high bandwidth chopper is used to produce the required bunch patterns. A 162.5 MHz CW RFQ accelerates the beam from 30 keV to 2.1 MeV. A concern with CW operation is that losses either within the RFQ or in the dowstream modules should be well-understood and remain very low to ensure safe and/or reliable operation. In this contribution, we investigate the suitability of existing RFQ codes and model the PXIE RFQ (ProjectX test facility) designed constructed by LBNL to make useful predictions of loss patterns and phase space distribution.