04 Hadron Accelerators

A08 Linear Accelerators

Paper Title Page
TUOBM02 The Development of the Separated Function RFQ Accelerator in Peking University 1007
 
  • X. Q. Yan, J.-E. Chen, J. X. Fang, S. L. Gao, Z. Y. Guo, Y. R. Lu, Z. Wang, K. Zhu
    PKU/IHIP, Beijing
  
  The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In order to demonstrate the feasibilities of the novel accelerator, a prototype cavity was designed and constructed. Correspondingly, a code SFRFQCODEV1.0 was developed specially for cavity design and beam dynamics simulation. The prototype cavity will be verified as a post-accelerator for ISR RFQ-1000 (Integral Split Ring RFQ) and accelerate O+ from 1 MeV to 1.6 MeV. To inject a higher current oxygen beam for the prototype cavity, the beam current of ISR RFQ-1000 was upgraded to 2 mA. The status of high power and beam test of the prototype cavity are presented in this paper.  
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THPP019 Adjustment of a New Pre-stripping Section the Multicharge Ion Linear Accelerator (MILAC) 3410
 
  • O. F. Dyachenko, V. A. Bomko, Ye. V. Ivakhno, A. P. Kobets, V. I. Misjura, V. V. Mytrochenko, A. V. Zabotin, B. V. Zajtsev
    NSC/KIPT, Kharkov
  
  In the Kharkov Institute of Physics and Technology the works on commissioning of a new prestripping section (A/q = 4), intend for accelerating a high current beam of light ions from 30 keV/u to 975 keV/u come to the end. Results of final tuning of irregular interdigital accelerating structure with alternating phase focusing and stepped changing the synchronous phase along the focusing period are presented. Process of preliminary adjustment of structure by means of traditional developed earlier methods: the additional current-carrying stems and the end resonant tuning elements (ERTEs) is described. New effective inductance-capacitor tuning devices as rods located on the drift tube side, opposite to their holders («contrivance») are developed and their use in real structure is shown. «Contrivances» have proved as the effective element of tuning locally influencing value of an electric field in the nearest gaps and lowering resonant frequency without noticeable worsening of electrodynamic characteristics of resonant system.  
THPP020 Progress in the ALPI -PIAVE Low-beta Section Upgrade 3413
 
  • A. Facco, F. Scarpa, D. Zenere
    INFN/LNL, Legnaro, Padova
  
  The low-b section of the PIAVE-ALPI superconducting linac is being upgraded in order to increase its energy gain from approximately 10 to about 20 MeV/q. This large increase of the accelerating voltage will be obtained by increasing by 20% the number of low-beta bulk niobium quarter-wave resonators and by upgrading the old rf system, underdimensioned in comparison with the resonator performance. This will lead to a significant enhancement of the linac capabilities, including the possibility of acceleration well above the Coulomb barrier heavy ions with any mass number. Status and technical details of the upgrade program will be described.  
THPP021 Status of the Unilac-upgrade Programme for the Heavy Element Research at GSI-Ship 3416
 
  • P. Gerhard, W. Barth, L. A. Dahl, K. Tinschert
    GSI, Darmstadt
  • A. Schempp
    IAP, Frankfurt am Main
  
  For more than 30 years the heavy-element research using the velocity separator SHIP is one of the major experiments at GSIs heavy ion linear accelerator UNILAC. On of the major contributions which led to the discovery of six new elements since 1981 is the perpetual effort to increase the beam intensity. Since the early 1990's the beam current available was raised significantly by a number of improvements concerning the source, the LEBT and the accelerator. The next steps are scheduled for 2009 and include an upgrade of the Radio Frequency Quadrupole-accelerator (RFQ) and a new superconducting 28 GHz-ECR ion source. The new RFQ will allow higher duty factors up to 100% and improve the longitudinal beam quality as well as the beam transmission. The new ion source will provide an increase in beam intensity and simultaneously higher charge states. The new source will be installed in addition to the existing one, therefore a second LEBT-system has to be designed and integrated into the High Charge State Injector. This paper presents the status quo of both the RFQ and the ion source upgrade and will provide technical data.  
THPP022 IH Linac with Higher-order Modes 3419
 
  • N. Hayashizaki, T. Hattori
    RLNR, Tokyo
  
  As one of a drift tube type linac, an Interdigital H-type (IH) linac has been applied for ion acceleration in low beta range. It can realize a resonant cavity of convenient size at low frequency band and higher shunt impedance at low velocity range. These characteristics are advantageous especially for heavy ion acceleration; therefore, this structure has been applied for heavy ion cancer therapy. The RF field is resonated in TE111 mode and the electric field does not have the axial field component. The accelerating field is excited by using the electrode of Interdigital shape. In order to apply this structure to intermediate beta range, we propose a IH linac with the TE11n mode of the higher-order mode (HOM). Although the operating frequency becomes higher by using HOM, it is convenient to accelerate ion beam of intermediate energy. The design of the cavity structure and the possibility are presented.  
THPP024 Detailed Study of the RF Properties of the FETS RFQ Cold Model 3422
 
  • S. Jolly, A. Kurup, D. A. Lee, J. K. Pozimski, P. Savage
    Imperial College of Science and Technology, Department of Physics, London
  • Y. Cheng
    IHEP Beijing, Beijing
  • A. P. Letchford
    STFC/RAL, Chilton, Didcot, Oxon
  
  A 324MHz four vane RFQ cold model has been built, as part of the development of a proton driver Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. Previous measurements to determine the electric field profile were made using the bead-pull perturbation method: these measurements have been refined and expanded. New measurements of the electric field profile, Q-value and resonant modes are presented. Measurements of the fundamental frequency and Q-value of the RFQ as a result of modifications to the profile of the end flange inserts are also given. Finally, an experiment is outlined to determine the beam transmission properties of the cold model based on beam transport simulations with the General Particle Tracer package (GPT).  
THPP025 Fabrication Status of the PEFP DTL II 3425
 
  • H. S. Kim, Y.-S. Cho, J.-H. Jang, H.-J. Kwon, B.-S. Park
    KAERI, Daejon
  
  The DTL II as a main part of the PEFP proton linac is under development. Following the DTL I which accelerates the proton beam up to 20 MeV, DTL II increases the proton energy from 20 MeV to 100 MeV. The DTL II consists of 7 tanks and each tank is composed of 3 sections whose length is about 2.2 m. The tank is made of seamless carbon steel and inside surface is electroplated with copper. Each drift tube contains an electroquadrupole magnet which is made of hollow conductor and iron yoke with epoxy molding. The status of development and test results of the fabricated parts are reported in this paper.  
THPP026 IH Accelerating Structures with PMQ Focusing for Low-energy Light Ions 3428
 
  • S. S. Kurennoy, S. Konecni, J. F. O'Hara, L. Rybarcyk
    LANL, Los Alamos, New Mexico
  
  We are developing high-efficiency room-temperature RF accelerating structures for beam velocities in the range of a few percent of the speed of light by merging two well-known ideas: inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we have proved that such structures provide a very efficient and practical accelerator for light-ion beams of considerable currents. The IH accelerating structures with PMQ focusing following a short RFQ can be used in the front end of ion linacs or in stand-alone applications such as a compact deuteron-beam accelerator up to the energy of a few MeV.  
THPP027 Heating and Stress in the LANSCE Side-coupled Linac RF Cavities 3431
 
  • S. S. Kurennoy, S. Konecni, J. F. O'Hara, L. Rybarcyk
    LANL, Los Alamos, New Mexico
  
  RF heating and related temperature distribution and stress are important problems in room-temperature accelerating cavities operating at high duty factors. To evaluate feasibility of higher duty operations of the Los Alamos Neutron Science Center (LANSCE) side-coupled linac (SCL), we have performed a combined 3-D electromagnetic (EM) and thermal-stress analysis of the SCL RF cavities. In the process, we have developed a procedure and interface for data exchange between the electromagnetic (MicroWave Studio) and engineering (COSMOS) codes for the combined EM-engineering analysis. This interface can be useful for other applications involving room-temperature accelerating cavities.  
THPP028 Beam Tests of the PEFP 20 MeV Accelerator 3434
 
  • H.-J. Kwon, Y.-S. Cho, I.-S. Hong, J.-H. Jang, D. I. Kim, H. S. Kim, B.-S. Park, K. T. Seol, Y.-G. Song, S. P. Yun
    KAERI, Daejon
  
  PEFP (Proton Engineering Frontier Project) 20 MeV proton accelerator has been installed and tested at KAERI (Korea Atomic Energy Research Institute) site. After the radiation license was issued, some parts were modified to increase a beam current above 1mA. Both an ion source and a LEBT (Low Energy Beam Transport) were modified for better matching of the beam into the 3 MeV RFQ. The field profile of the RFQ was measured to check the dipole field effect. In addition, control mechanisms to improve the RF properties of 20 MeV DTL were newly adopted. In this paper, the modifications of the 20MeV accelerator are summarized and the test results are presented.  
THPP029 Status of the RAL Front End Test Stand 3437
 
  • A. P. Letchford, M. A. Clarke-Gayther, D. C. Faircloth, D. J.S. Findlay, S. R. Lawrie, P. Romano, P. Wise
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • S. M.H. Al Sari, S. Jolly, A. Kurup, D. A. Lee, P. Savage
    Imperial College of Science and Technology, Department of Physics, London
  • J. Alonso, R. Enparantza
    Fundación Tekniker, Elbr (Guipuzkoa)
  • J. J. Back
    University of Warwick, Coventry
  • F. J. Bermejo
    Bilbao, Faculty of Science and Technology, Bilbao
  • C. Gabor, D. C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • J. Lucas
    Elytt Energy, Madrid
  • J. Pasternak, J. K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon
  
  High power proton accelerators (HPPAs) with beam powers in the several megawatt range have many applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. The UK's commitment to the development of the next generation of HPPAs is demonstrated by a test stand being constructed in collaboration between RAL, Imperial College London, the University of Warwick and the Universidad del Pais Vasco, Bilbao. The aim of the RAL Front End Test Stand is to demonstrate that chopped low energy beams of high quality can be produced and is intended to allow generic experiments exploring a variety of operational conditions. This paper describes the current status of the RAL Front End Test Stand.  
THPP031 Upgrade of the ISAC DTL Tuning Procedure at TRIUMF 3440
 
  • M. Marchetto, J. Berring, R. E. Laxdal
    TRIUMF, Vancouver
  
  The TRIUMF ISAC facility has two variable energy heavy ion linacs as post accelerators for radioactive ion beams. The ISAC I linac is a warm IH-DTL with five accelerating tanks and three bunchers, the ISAC II one uses twenty independently phased superconducting cavities. The first linac operates between 150 keV/u and 1.8 MeV/u; the second boosts the 1.5 MeV/u injected beam by 20 MV. The DTL is tuned based on the energy beam profile given by an analysing magnet. The SC linac is tuned on energy and time profiles with a diagnostic based on a gold foil scattering ions to a silicon detector (SID). The SID requires lower beam intensity. Furthermore the tuning time is reduced and streamlined by means of a MATLAB graphical user interface (GUI). This GUI uses a simple cosine model to characterize the energy gain versus RF phase of each cavity. Based on this we have pursued a new tuning procedure for the DTL using a gold foil/SID diagnostic. The more complex RF structures of the DTL require measurements and beam dynamics simulations (with LANA code) to produce a model for a dedicated GUI. In the paper we describe the two existing tuning methods and present new DTL procedure and interface.  
THPP034 Design Study of Alternate Injector at Pelletron Accelerator Facility 3443
 
  • N. Mehrotra, P. V. Bhagwat, R. K. Choudhury, A. K. Gupta, S. Kailas, S. Krishnagopal
    BARC, Mumbai
  • R. G. Pillay
    TIFR, Mumbai
  
  An alternate injector system is contrived under the AIDNP project in the Xth plan to utilize the 150MHz supercond. LINAC to its full capability. This injection system consists of ECR ion source, RFQ Linac and supercond. QWR cavities. This configuration can deliver high current and wider mass range(1/7≤ q/m≤1/2) beam into the S-LINAC with the required velocity acceptance which otherwise is not possible from pelletron. The design study from ion source to exit of RFQ is presented in this paper. Prior to injection to s-linac,the beam needs to be accelerated to an equivalent of 12-14MV/q. Beam from a high frequency(18GHz) ECRsource producing Au30+,U34+ and pre accelerated to 10keV/u will be injected into heavy ion RFQ. The RFQ operating at f/2 i.e.75MHz of the linac frequency, will accept beams with β=0.46% and accelerate upto β=3.5%.These beams would then go through two sets of superconductiong cavities with β=5.0% and β=7.0% respectively. This acceleration is expected to bring all ion beams from carbon to uranium, in the velocity range β=8%-10% which is suitable for linac. After further acceleration in Linac~12 MeV/u light ions and 7 MeV/u uranium beams would be available.  
THPP036 The Superconducting Solution for the EURISOL DS Postaccelerator Injector 3446
 
  • P. A. Posocco
    Consorzio RFX, Euratom ENEA Association, Padova
  • G. Bisoffi, A. Palmieri, A. Pisent, P. A. Posocco
    INFN/LNL, Legnaro, Padova
  
  In the framework of EURISOL design study*, the superconducting solution for the Post-Accelerator injector foresees the use of two RFQs, one Super Conducting and one Normal Conducting, both operating CW at 88 MHz. After the multiple ionization in the ECR breeder on low voltage platform, the rare ions beam (3 ≤ A/q ≤ 7) is bunched at the main frequency by the NC RFQ without both losses and transverse emittance increase and accelerated afterwards through the SC RFQ up to 560 keV/u. A 8.8 MHz pulsed beam can be delivered to experiments placing a 3 harmonic buncher before the NC RFQ with overall beam losses lower than 25%. The beam dynamics results of the study of this solution as well as the main RF design and construction analysis of the main components are presented.

*http://www.eurisol.org

 
THPP037 A Decelerator for Heavy Highly Charge Ions at HITRAP 3449
 
  • J. Pfister, B. Hofmann, U. Ratzinger, A. Schempp
    IAP, Frankfurt am Main
  • W. Barth, L. A. Dahl, P. Gerhard, O. K. Kester, W. Quint, T. Stoehlker
    GSI, Darmstadt
  
  The heavy highly charged ion trap (HITRAP) project at GSI is in the commissioning phase. Highly charged ions up to U92+ provided by the GSI accelerator facility will be decelerated and subsequently injected into a large Penning trap for further cooling almost to rest. A combination of an IH- and an RFQ-structure decelerates the ions from 4 MeV/u down to 6 keV/u. In front of the decelerator a double drift-buncher-system provides for phase focusing and a final de-buncher integrated in the RFQ-tank reduces the energy spread in order to improve the efficiency for beam capture in the cooler trap. This contribution concentrates on the beam dynamics simulations and corresponding measurements in the first commissioning beam times.  
THPP038 Phase 1 Commissioning Status of the 40 MeV Proton/Deuteron Accelerator SARAF 3452
 
  • C. Piel, K. Dunkel, F. Kremer, M. Pekeler, P. vom Stein
    ACCEL, Bergisch Gladbach
  • D. Berkovits, I. Mardor
    Soreq NRC, Yavne
  
  Since January 2007 all accelerator equipment of the Phase 1 for the 40MeV Proton/Deuteron Accelerator is at the SARAF site and installed for the commissioning. The target of Phase 1 is to get the ECR ion source and RFQ into operation and to perform all relevant test with the cryo module housing 6 super conducting half wave resonators, to show that the design values of the system can be reached. Based on those results the Phase 2 shall start, to reach the final energy of 40MeV with up to 2mA of Protons and Deuterons. The ECR source is in routine operation since June 2006, the RFQ already have been operated with Protons and currently is under characterisation. After the characterisation has been finalised it is anticipated to move the cryo module in the beam line and to perform further beam characterisation. The entire beam characterisation is closely followed by beam dynamics simulations. Recent results of the commissioning will be presented and comparisons made between measurements and beam dynamics calculations.  
THPP040 Choice of Accelerating System for Undulator Linear Accelerator 3455
 
  • E. S. Masunov, N. V. Avreline, V. S. Dyubkov, S. M. Polozov
    MEPhI, Moscow
  • A. L. Sitnikov
    ITEP, Moscow
  
  The undulator linear accelerators (UNDULAC) were suggested as a new type of high intensity low energy ion linac. Such accelerators can be realized in periodical IH structure. The RF field in UNDULAC has no spatial harmonics in synchronism with the beam*. An accelerating force is to be driven by a combination of two non-synchronous space harmonics. The ratio of first to zero RF field harmonics amplitude must be equal to 0.25-0.4. The effective beam bunching and focusing could be provided in this case. The construction of UNDULAC accelerating channel is discussed to realize such ratio. The first results of IH resonator type choice are also presented.

*E. S. Masunov, Technical Physics, V. 46, 11, 2001, pp. 1433-1436.

 
THPP041 Beam Dynamics Simulation of the 1.5 MeV/u Proton/Deuteron Beams Measured at the SARAF RFQ Exit 3458
 
  • J. Rodnizki, B. Bazak, D. Berkovits, G. Feinberg, A. Shor, Y. Yanay
    Soreq NRC, Yavne
  • K. Dunkel, C. Piel
    ACCEL, Bergisch Gladbach
  
  The Soreq Applied Research Accelerator Facility (SARAF) accelerator's front-end is composed of a 20 keV/u protons and deuterons ECR ion source, a 5 mA low energy beam transport and a 1.5 MeV/u, 4 mA, 176 MHz, 4-rod RFQ. In this work, beam dynamics simulations of the SARAF accelerator front-end is compared to the first beam measurements taken during commissioning. Beam transmission, ion energy and bunch width as a function of the RFQ power have been measured in the medium energy beam transport diagnostics and using a dedicated diagnostic plate. The simulations and measurements show similar trends. This agreement allows calibrating the RFQ power to its electrodes voltage, in the low electric field range, where the common x-ray measurement method is not feasible. The benchmark between simulation and measurement shows that the RFQ model in our simulation can well predict the measured values. The simulation is covering the beam tail as well and is used to find the optimal operating voltage by minimizing the low energy tail and hence the beam loss downstream the accelerator.  
THPP044 Experience with the SNS SC Linac 3461
 
  • Y. Zhang, A. V. Aleksandrov, C. K. Allen, I. E. Campisi, S. M. Cousineau, V. V. Danilov, J. Galambos, J. A. Holmes, D.-O. Jeon, S.-H. Kim, T. A. Pelaia, A. P. Shishlo
    ORNL, Oak Ridge, Tennessee
  
  The SNS SC linac (SCL) is designed to deliver 1 GeV, up to 1.56 MW pulsed H- beams for neutron production. Beam commissioning of the SNS accelerator systems completed in June 2006 with the maximum linac output beam energy approximately 952 MeV. In 2007, we successfully tuned the SCL for 1 GeV beams during a test run, and the SNS linac achieved its design energy for the first time. During the linac tune-up, phase scan signature matching, drifting beam measurement as well as linac RF cavity phase scaling was applied. In this paper, we will introduce the experiences with the SCL, and we will also briefly discuss beam parameter measurements.


 
THPP079 Design of the High Current Linac of SPES Project 3545
 
  • A. Pisent, M. Comunian, E. Fagotti, A. Palmieri, P. A. Posocco
    INFN/LNL, Legnaro, Padova
  • F. Grespan
    Università degli Studi di Milano, Milano
  
  The proposed driver, composed by a four vanes RFQ and an Alvarez DTL, generates a high intensity beam, for an average current of 1.5 mA and an energy of 43 MeV, upgradable to 95 MeV. The high rep rate (50 Hz) is necessary for the correct mechanical behavior of the target. The accelerator is composed by the source TRIPS, built at LNS and now in operation at LNL, by the RFQ of TRASCO research program (5 MeV 30 mA), very advanced in the construction, and by a normal conducting Drift Tube Linac (DTL). This last accelerating structure is the same proposed for LINAC4 at CERN. A prototype of this structure, of interest for both projects, is in construction in Italy with the joint effort of CERN and LNL. The RFQ and the two tanks of the DTL are fed by 3 klystrons; the first one, with a power of 1.3 MW, is already at LNL, while the other two with a power of 2.5 MW each are the same adopted for LINAC4. The power supply of the RF system (50 Hz 0.6 ms) has been evaluated in details on the bases of the system in operation for the Japanese project JPARC. This paper illustrates the physical design and beam dynamics studies of this linac.