IAP, Frankfurt am Main
GSI, Darmstadt
Funding: Work supported by BMBF
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum will comprise a short 175 MHz linac sequence consisting of a 1.4 m long 700 keV 4-rod type RFQ followed by a 50 cm IH-DTL for proton acceleration up to 2 MeV. The beam current is 200 mA at pulsed and 30 mA at cw operation. The aim is to have a very compact device driven by only one rf amplifier to reduce costs and required installation space. A coupling between the RFQ and the IH resonators by means of a galvanic connection is foreseen, which is realized by two brackets going right away through a common partitioning end flange lid. The accelerators could also be driven separately by just removing the brackets. The distance between the end of the RFQ electrodes and the middle of the first DTL gap is only 5 cm, there is no additional beam optics in between. Preliminary beam dynamics and rf simulations have been carried out together with accompanying measurements on rf models.
IAP, Frankfurt am Main
The Frankfurter neutron source at Stern-Gerlach-Zentrum (SGZ) uses a proton injector as a driver for the 7Li(p,n) neutron production. A volume type ion source will deliver a 100 keV, 200 mA proton beam continuously. It is intended to use a LEBT section consisting of four solenoids to transport the beam and to match it into the acceptance of the RFQ. A chopper system between solenoid 2 and 3 will provide beam pulses with a length of about 100 ns with a repetition rate of 250 kHz. The RFQ and the following IH drift tube LINAC will be coupled together to achieve an efficiency beam acceleration. Furthermore only one power amplifier will be needed to provide the rf power for both accelerator stages. The Mobley type bunch compressor will merge 7 micro-bunches formed in the accelerator module to one single 1ns bunch with an estimated peak current of about 8.6 A. A rebuncher will provide the post acceleration at a final beam energy adjustable between 1.8 and 2.4 MeV. The whole injector suffers from the high beam intensity and therefore high space charge forces. It will gives the opportunity to develop new accelerator concepts and beam diagnostic technics.
JAEA, Ibaraki-ken
MELCO SC, Tsukuba
Visual Information Center, Inc., Ibaraki-ken
KEK/JAEA, Ibaraki-Ken
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
Total Saport System Corp., Naka-gun, Ibaraki
Linac of J-PARC began to operate in November, 2006, and a achieved an initial performance in January, 2007. Afterwards, the beam supply to RCS begins, and it is operating extremely well with stability up to now. Here, the evaluation for comparison of the design and realities of architecture and performance of the LINAC control system are shown. Especially, the conceptual idea of function arrangement in the hierarchy of the control system architecture is shown. Now, the linac control system is in the second phase for the high power beam and reducing the beam loss, and the analysis of the system response identification for the high precision beam control is started.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
JAEA, Ibaraki-ken
J-PARC, KEK & JAEA, Ibaraki-ken
The J-PARC (Japan Proton Accelerator Research Complex) linac consists of an RFQ, a Drift Tube Linac and a Separated-type Drift Tube Linac. The beam commissioning of the linac started in November 2006 and 181 MeV acceleration was successfully achieved in January 2007. The linac has delivered beams to the 3 GeV Rapid Cycling Synchrotron for its commissioning, and then, the subsequent 50 GeV Main Ring Synchrotron and the neutron target commissioning. The linac uses 20 units of 324 MHz klystrons. As of May, 2008, the average number of filament hours exceeds 5,000 without serious troubles. The operating experience of the linac will be described in this paper.
KAERI, Daejon
A 20 MeV proton accelerator, which consists of a 50 keV injector, a 3 MeV RFQ and a 20 MeV DTL, has been tested by Proton Engineering Frontier Project (PEFP) at Korea Atomic Energy Research Institute (KAERI. The operation conditions are 20 MeV, 20 mA peak current, 50 μs pulse length with a 1 Hz repetition rate due to the limited radiation shielding. The accelerator was tuned to reach to the above operating conditions. Moreover, an irradiation facility with external beam has been installed to supply the proton beam for the user and irradiation test. In this paper, we present results from tuning operation and the irradiation tests.
RAS/INR, Moscow
Instead of proved application of superconducting structures for high energy part of intense linear proton accelerators, normal conducting structures are still considered for medium and low energy parts below 200 MeV. Operation with accelerating rate ~4 MeV/m and duty factor ~5% results for standing wave normal conducting structure in an average heat loading ~30 kW/m. Due to the high heat loading an operating mode frequency shift is significant during operation. In this paper conditions for field distribution stability against small deviations in time of individual cell frequencies are considered. For pi/2 structures these conditions were formulated by Y. Yamazaki and L. Young. General case of 0, pi/2 and pi operating modes is considered with common approach.
CERN, Geneva
Linac4 is a 160 MeV, 40 mA H- linear accelerator which will be the source of particles for all CERN proton accelerators from 2013. Its construction has started in 2008, as part of a program for the progressive replacement or upgrade of the LHC injectors during the next decade. Linac4 will initially inject into the PS Booster and at a later stage into a 4 GeV Superconducting Proton Linac (SPL), which could ultimately be upgraded to high duty cycle operation. For this reason accelerating structures, rf hardware and shielding of Linac4 are dimensioned for higher duty from the initial phase. Linac4 is normal-conducting, 80 m long and consists of an rf volume ion source, an RFQ, a beam chopping section and a cascade of three different types of 352 MHz accelerating structures. Its main design requirements are high reliability, high beam brightness and low beam loss. The accelerator will be housed in an underground tunnel on the CERN site, which can eventually be extended to the SPL, with equipment installed in a surface building above. The main parameters, the status of the main components, the planning, the project organisation and the civil engineering infrastructure are presented.
CERN, Geneva
BINP SB RAS, Novosibirsk
RFNC-VNIITF, Snezhinsk, Chelyabinsk region
The 352 MHz CCDTL will accelerate the Linac4 beam from 50 to 102 MeV. It will be the first CCDTL used in a proton linac. Three short DTL tanks, each having two drift tubes, are connected by coupling cavities and form a chain of 5 resonators operating in the stable π/2 mode. The CCDTL section is made of 7 such chains, each fed by a 1.3 MW klystron. Focusing quadrupoles are placed between tanks, easing their alignment with respect to a conventional DTL thus making the structure less sensitive to manufacturing errors. In order to validate the design and to develop the production technology, two prototypes have been constructed and successfully tested. The first prototype, built at CERN, consists of two half-cavities and one coupling cell, whereas the second, with two full cavities and one coupling cell, was built at VNIITF and BINP in Russia in the frame of an R&D contract funded by the ISTC Organisation. Both prototypes have been tested at CERN slightly beyond their nominal power level, at the design duty cycle of 10%. In this paper we present the results of high-power tests, the results of the technological developments prior to production, and the final design of the CCDTL.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
Fundación Tekniker, Elbr (Guipuzkoa)
University of Warwick, Coventry
Bilbao, Faculty of Science and Technology, Bilbao
Fundación TEKNIKER, Eibar (Gipuzkoa)
STFC/RAL, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Elytt Energy, Madrid
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.
Fermilab, Batavia
Kentech Instruments Ltd., Wallingford, Oxfordshire
A fast chopper capable of kicking single 2.5 MeV H- bunches, spaced at 325 MHz, at rates greater than 50 MHz is needed for the Fermilab High Intensity Neutrino Source (HINS). Four 1.2 kV fast pulsers, designed and manufactured by Kentech Instruments Ltd., will drive a ~0.5m long meander made from a copper plated ceramic composite. Test results showing pulses from the prototype 1.2 kV pulser propagating down the meander will be presented.
Fermilab, Batavia
TRIUMF, Vancouver
Muons, Inc, Batavia
JLAB, Newport News, Virginia
Modern technology allows us to consider operating an 8 GeV Linac in a cw mode to accelerate a high-current H- beam. By using appropriate accumulation rings, the linac could provide simultaneous beams for direct neutrino production, neutrino factories, fixed target experiments, and muon colliders. Several other unique accelerator applications could also be served and improved by the same continuous beam, including studies of energy production and nuclear waste reduction by transmutation, rare muon decay searches, and muon catalyzed fusion. The trade-offs between cw operation compared to pulsed operation that are considered include the maximum rf gradient and corresponding linac length or energy, the rf frequency, rf peak power and coupler requirements, and refrigeration. Methods for accumulating the beam from a cw linac to serve the special needs of the potential future Fermilab programs mentioned above are considered. In this paper we also examine the use of a cyclotron as a source of high current beams to reduce the cost and complexity of the linac front end.
Fermilab, Batavia
IUCF, Bloomington, Indiana
The High Intensity Neutrino Source (HINS) R&D program at Fermilab will build a new 65 MeV test linac to demonstrate new technologies for application in a high intensity hadron linac front-end. The HINS warm section is composed of an ion source, a radio frequency quadrupole, a medium energy beam transport and 16 room temperature Crossbar H-type (RT-CH) cavities that accelerate the beam to 10 MeV (β=0.1422). The RT-CH cavities are separated by superconducting solenoids enclosed in individual cryostats. Beyond 10 MeV, the design uses superconducting spoke resonators. In this paper, we illustrate the completion of four RT-CH cavities and explain latest modifications in the mechanical and radio frequency (RF) designs. Cavities RF measurements and tuning performed at Fermilab are also discussed. Descriptions of the HINS R&D Facility including high power RF, vacuum, cooling and low level RF systems will be given. Finally, the history of RF conditioning and the results of high power tests of RT-CH cavities will be discussed.
Fermilab, Batavia
Low energy part of the linac for the HINS project at Fermilab will use superconducting solenoids as beam focusing elements (lenses). While lenses for the conventional, DTL-type accelerating section of the front end require individual cryostats, in the superconducting accelerating sections solenoids will be installed inside rf cryomodules. Some of the lenses in the conventional and in the superconducting sections are equipped with horizontal and vertical dipole correctors. Lenses for the conventional DTL section are in the stage of production with certification activities ongoing at Fermilab. For the superconducting sections of the linac, several prototypes of focusing lenses were built and tested. Solenoid magnetic axis is used for alignment of the lenses in the transport channel of the accelerator. Corresponding technique has been developed at Fermilab and is used during certification of the production lenses for the DTL section. This report will summarize main design features, parameters, and test results of the focusing lenses of the linac. Magnetic axis alignment technique will also be described.
LANL, Los Alamos, New Mexico
The Los Alamos Neutron Science Center (LANSCE) accelerator is an 800 MeV proton linac that drives user facilities for isotope production, proton radiography, ultra-cold neutrons, weapons neutron research and various sciences using neutron scattering. The LANSCE Refurbishment Project (LANSCE-R) is an ambitious project to refurbish key elements of the LANSCE accelerator that are becoming obsolete or nearing end-of-life. The conceptual design phase for the project is funded and underway. The 5 year, $170M (US) project will enable future decades of reliable, high-performance operation. It will replace a substantial fraction of the radio-frequency power systems (gridded tubes and klystrons) with modern systems, completely refurbish the original accelerator control and timing systems, replace obsolete diagnostic devices, and modernize other ancillary systems. An overview of the LANSCE-R project will be presented. The functional and operating requirements will be discussed, the proposed technical solutions presented, and the plan for successful project execution while meeting annual customer expectations for beam delivery will be reviewed.
LANL, Los Alamos, New Mexico
Funding: U. S. Department of Energy, National Nuclear Security Administration, Contract No. DE-AC52-06NA25396
The Los Alamos Neutron Science Center (LANSCE) continues to be a signature experimental science facility at Los Alamos National Laboratory (LANL). The 800 MeV linear proton accelerator provides multiplexed beams to five unique target stations to produce medical radioisotopes, ultra-cold neutrons, thermal and high-energy neutrons for material and nuclear science, and to conduct proton radiography of dynamic events. Recent operating experience will be reviewed and the role of an enhanced LANSCE facility in LANL's new signature facility initiative, Matter and Radiation in Extremes (MaRIE) will be discussed.
LA-UR-08-03581
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The Spallation Neutron Source accelerator complex uses set of pulsed linear accelerators of different types to accelerate beam to 1 GeV. The 2.5 MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. In the process of the commissioning and beam power ramp up many technical systems, as well as tuning algorithms, have deviated significantly from the original design. Our understanding of beam behavior has been evolving continuously and resulted in a steady reduction of fractional beam losses in the linac. In the same time new unexpected problems have been discovered, which are still in the process of investigation. In this paper we summarize our experience up to date and report on the current directions of experimental study, simulations, and development of tuning methods.
TRIUMF, Vancouver
The ISAC-III proposal is a ten year plan to triple the amount of radioactive ion beam (RIB) time at the facility. The plan includes the addition of two new independent target stations with a design suitable for actinide target materials, a second 500 MeV proton beam line from the TRIUMF cyclotron and a new 50 MeV electron linac as a complementary driver to provide RIBs through photo-fission. The two new target stations will require a new mass-separator and low-energy beam-transport complex to deliver the additional beams to the ISAC experimental facilities. It is also proposed to install a new linear accelerator section to provide the capability for two simultaneous accelerated RIBs to experimenters. This paper will describe the proposed installations in the low-energy transport and accelerator sections of the ISAC complex.
TRIUMF, Vancouver
The ISAC-II superconducting linac, operational since April 2006, adds 20 MV accelerating potential to the ISAC Radioactive Ion Beam (RIB) facility. An upgrade to the linac, in progress, calls for the addition of a further 20 MV of accelerating structure by the end of 2009. The new installation consists of twenty 141 MHz quarter wave cavities at a design beta of 11%. The cavities will be housed in three cryomodules with six cavities in the first two cryomodules and eight cavities in the last. A second Linde TC50 refrigerator has been installed and commissioned to provide cooling for the new installation. The design incorporates several new features as improvements to the existing cryomodules. They include a four point support frame for the cavity strongback, a modified LN2 circuit internal to the cryomodule and a new design for the mechanical motion of the rf coupling loop. A summary of the design and the current status of the cryomodule production and supporting infrastructure will be presented.
GSI, Darmstadt
IAP, Frankfurt am Main
For injection into the ion trap facility HITRAP, the GSI accelerator complex has the unique possibility to provide beams of highly stripped ions and even bare nuclei up to Uranium at an energy of 4 MeV/u. The HITRAP facility consists of linear 108 MHz-structures of IH- and RFQ-type to decelerate the beams further down to 6 keV/u for capturing in a large penning trap for cooling purpose. The installation is completed except of the RFQ-tank. During commissioning periods in 2007 64Ni28+ and 20Ne10+ beam was used to investigate the beam optics from the experimental storage ring extraction to the HITRAP double-drift-buncher system. In 2008 the IH-structure decelerator and the downstream matching section was examined with 197Au79+ beam. Comprehensive beam diagnostics were installed: Faraday cups, tubular and short capacitive pick ups, SEM grids, YAG scintillation screens, a single shot pepperpot emittance meter, and a diamond detector for bunch shape measurements. Results of the extensive measurements are presented.
DAE/VECC, Calcutta
An ISOL (Isotope Separator On Line) type of RIB (Radioactive Ion Beam) facility* is being developed at our centre. The post-acceleration scheme will consist of a Radio Frequency Quadrupole** (RFQ) followed by a few IH LINAC cavities - further augumentation of energy using SC QWRs will be taken up at a later stage. The first two IH cavities have been designed for 37.6 MHz frequency like the preceding RFQ to keep the rf defocusing smaller. Explosively bonded copper on steel has been used for the fabrication of the IH cavities (1.72 m inner diameter, 0.6 m and 0.87 m lengths) and the inner components have been made out of ETP grade copper. Also, we have adopted an octagonal cavity structure to avoid fabrication complicacies. Thermal analysis of the cavities have been carried out and cooling configurations have been optimized accordingly to control the temperature rise of the LINACs. Detailed mechanical analysis has been carried out to reduce the deflection of the LINAC components under various loads. Design and fabrication aspects of these two cavities and results of the low power tests will be reported in this paper.
* Alok Chakrabarti et. al. ; Proc. Part. Accl. Conf. 2005, pp-395.
** Alok Chakrabarti et. al. ; Nucl. Instr. & Meth., A535 (2004) 599.
DAE/VECC, Calcutta
An ISOL type Rare Isotope Beam (RIB) Facility is being developed at VECC, Kolkata around the existing K=130 room temperature cyclotron. The possibility of using the photo-fission production route using a 50 MeV electron linac is also being explored. The production target and a 6.4 GHz ECR based charge-breeder system will lead to two beam lines. The first one, a low energy beam transport (LEBT) line consisting of a 1.7 m long, 33.7 MHz RFQ, will be dedicated to material science & other ion-beam based experiments. The second, post-acceleration beam line will accelerate the beams to 1.3 MeV/u using a longer, 3.4 m RFQ and a series of IH linear accelerators. In the first stage, the beam energy will be about 400 keV/u using three modules of linacs. Subsequently the energy will be boosted to about 1.3 MeV/u. Some of the systems have already been installed and made operational. The LEBT line has been tested and stable ion beams accelerated to 29 keV/u with high efficiency in the 1.7 m RFQ. The 3.4 m RFQ and the first IH Linac tank are under installation in the post-acceleration beam line. In this contribution an overview of the present status of the facility will be presented.
INFN/LNL, Legnaro, Padova
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova
The SPES project* at Laboratori Nazionali di Legnaro foresees the contruction of a RIB facility based on a fission target driven by a 40 MeV proton beam. After the 238U carbide target the 1+ charged ions will be selected by a high resolution mass spectometer, charge enhanced by a charge breeder and accelerated up to 10 MeV/A for 132Sn. The Legnaro superconducting accelerator complex, PIAVE injector and ALPI main accelerator, in its present configuration fits the requirements for SPES post acceleration. Nevertheless an upgrade of its performaces both in overall transmission and final energy is needed and a solution which minimizes the impact on the present structures will be presented.
*http://www.lnl.infn.it/~spes/
RIKEN Nishina Center, Wako, Saitama
Present status of the RIKEN heavy-ion linac (RILAC) will be reported, which has been used for the injector to the RIKEN RI-beam factory since 2006 as well as for the nuclear physics experiments on superheavy elements since 2002. An alternative injector to the RI-beam factory, consisting of a superconducting ECR ion source, an RFQ, and three DTLs, will be also discussed. The construction of the ion source will be completed in this year and the extraction test of the beams will be started from 2009. An RFQ linac, originally developed for the ion implantation*, was given to RIKEN through the courtesy of Kyoto University. Reconditioning of this RFQ is underway, which will be modified for the new injector in the near future.
*H. Fujisawa: Nucl. Instrum. Methods A345, 23 (1994).
PKU/IHIP, Beijing
Funding: Supported by NSFC (10775009)
The methodology for low energy spread RFQ beam dynamics design has been studied for 14C+ AMS application. This paper will present a low energy beam dynamics and rf design for a new trapezoidal IH-RFQ. It will accelerate 14C from 40 keV to 500 keV with the length of 1.1 m; operate at 104 MHz with the rf peak power less than 27 kW. The transmission efficiency is better than 95% and the energy spread is as low as 0.6%. The rf structure design and its rf efficiency have been studied by electromagnetic simulation. It shows such trapezoidal IH-RFQ has higher operating frequency than normal IH-RFQ, and it will have more longitudinal accelerating efficiency.
PKU/IHIP, Beijing
Funding: supported by NSFC 10455001
Longer the RFQ length is, lower kinetic energy gain per unit length is; lower the injection energy DTL is, much higher accelerating efficiency is; more accelerating gaps at DTL entrance means stronger transverse focusing is needed for the beam. SFRFQ is such an intermediate structure, which combines RFQ and DTL together, it can increase the accelerating efficiency at RFQ high energy end by inserting gap acceleration between RFQ electrodes while provide strong focusing by RFQ focusing field. One prototype cavity has been manufactured and will be used as a post accelerator of ISR RFQ to accelerate O+ from 1 MeV to 1.6 MeV in 1meter. A code SFRFQCODEV1.0 was developed for the beam dynamics design. The rf conditioning and full rf power test has been carried out. The intervane or gap voltage have reached 86 kV at 29 kW with 1/6 duty cycle and repetition frequency 166 Hz. The initial beam test results will also be presented in this paper.
JINR, Dubna, Moscow Region
IHEP Protvino, Protvino, Moscow Region
Goal of the NICA/MPD project under realization at JINR is to start in the coming 5-7 years an experimental study of hot and dense strongly interacting QCD matter and search for possible manifestation of signs of the mixed phase and critical endpoint in heavy ion collisions. The Nuclotron-based Ion Collider fAcility (NICA) and the Multi Purpose Detector (MPD) are proposed for these purposes. The NICA collider is aimed to provide experiment with heavy ions like Au, Pb or U at energy up to 3.5 x 3.5 GeV/u with average luminosity of 1027 cm-2s-1. The existing Nuclotron injection complex consists of HV fore-injector and Alvarez-type linac LU-20. The LU-20 accelerates the protons up to the energy of 20 MeV and ions at Z/A=0.33 up to the energy of 5 MeV/u. New injector designed for efficient operation of the NICA facility is based on Electron String Ion Source providing short (< 10 ns) and intensive (up to 10 mA) pulses of U32+ ions, one section of RFQ and four sections of RFQ Drift Tube Linac accelerating the ions at Z/A=0.12 up to 6 MeV/u of the kinetic energy. General parameters of the injector are discussed.
CERN, Geneva
UMAN, Manchester
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
The High Intensity and Energy ISOLDE (HIE-ISOLDE) proposal is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities with the objective of increasing the energy and the intensity of the delivered radioactive ion beam. For the energy increase a staged construction of a superconducting linac based on sputtered quarter wave cavities is foreseen downstream of the present normal conducting linac. A funded R&D program has been launched at the end of 2007 in order to prepare a full Technical Design Report covering all the issues of such a linac, including cavity prototyping and testing, cryomodule design, beam dynamics and beam diagnostics. We report here on the status and planning of the R&D activities for the SCREX-ISOLDE linac.
CERN, Geneva
UMAN, Manchester
For the REX-ISOLDE upgrade a superconducting linac based on 101.28 MHz Quarter Wave Resonators (QWRs) is foreseen downstream the normal conducting (NC) linac. Currently the REX-ISOLDE linac can accelerate ions with a mass to charge ratio in the range of 3 < A/q < 4.5 and up to an energy of 3 MeV/u. The upgrade aims to reach a final beam minimum energy of 10 MeV/u for A/q=4.5 in two main stages. The first stage consists of installing two cryomodules loaded with 10 cavities able to reach 5.5 MeV/u at the end of the present linac and the second consists of replacing part of the existing NC linac and adding further cryomodules. We report here on a beam dynamics study of the accelerator for the two installation stages and the transport line to the experimental station.
NSCL, East Lansing, Michigan
Funding: Work was supported by DOE grant DE-FG02-04ER41324
The proposed Facility for Radioactive Ion Beams (FRIB)* will deliver up to 400 kW of any stable isotope to multi-target experimental complex. Operational efficiency will be best served by a system that can distribute the beam current, variable in a large dynamic range, to several independent targets simultaneously. The proposed FRIB Beam Switchyard (BSY) utilizes an rf kicker with subsequent magnetostatic septum system to split the beam on micro-bunch to micro-bunch basis. The micro-bunches can be differentially loaded at the front-end of the Driver Linac**. The detailed analysis of the beam dynamics performance in the proposed BSY system is presented.
*D.Gorelov, et al, proc of EPAC 2002, Paris, France, 2002.
**M. Doleans, et al, LINAC 2006, Knoxville, TN, USA, 2006.
LLNL, Livermore, California
LBNL, Berkeley, California
Voss Scientific, Albuquerque, New Mexico
Funding: Work performed under the auspices of the U.S. Department of Energy under contract DE-AC52-07NA27344 at LLNL, and University of California contract DE-AC03-76SF00098 at LBNL.
We estimate the energy fluence (energy per unit area) at the focal plane of a beam undergoing neutralized drift compression and neutralized solenoidal final focus, as is being carried out in the Neutralized Drift Compression Experiment (NDCX) at LBNL. In these experiments, in order to reach high beam intensity, the beam is compressed longitudinally by ramping the beam velocity (i.e. introducing a velocity tilt) over the course of the pulse, and the beam is transversely focused in a high field solenoid just before the target. To remove the effects of space charge, the beam drifts in a plasma. The tilt introduces chromatic aberrations, with different slices of the original beam having different radii at the focal plane. The fluence can be calculated by summing the contribution from the various slices. We develop analytic formulae for the energy fluence for beams that have current profiles that are initially either constant or parabolic in time. We compare with envelope and particle-in-cell calculations. The expressions derived are useful for predicting how the fluence scales with accelerator and beam parameters.
ITEP, Moscow
GSI, Darmstadt
Funding: Work supported by the European Community INTAS Project Ref. no. 06-1000012-8782.
For the operation of the GSI-accelerator chain as an injector for the future FAIR facility a considerable increase of the heavy ion beam intensity by a factor 3-5 at the end of the UNILAC is required. The bottleneck of the whole UNILAC, is the front-end system of the High Current Injector. It is shown that the transverse RFQ-acceptance can be significantly increased while the emittance growth can be reduced. Both goals are achieved with only a moderate change of the RFQ electrode geometry; the intervane voltage raised from 125 kV to 155 kV keeping the design limit of the maximum field at the electrode surface. The changed resonant frequency can be compensated with a relatively small correction of the carrying rings. The beam parameters in the final focusing elements of the LEBT were improved together with the input radial matcher design; the length of the gentle buncher section was considerably increased to provide slow and smooth bunching resulting in a reduce influence of space charge forces. DYNAMION-simulation with the modified electrode design resulted in an increase of U4+-beam current of up to 20 emA. It is planned to start the upgrade measure in spring 2009.
IAP, Frankfurt am Main
BNL, Upton, Long Island, New York
A new RFQ is being built as a part of the new EBIS-linac at BNL. The RFQ accepts highly charged ions from the EBIS ion source with energy of 17 keV/u and ion currents of up to 10 mA. The operation frequency will be 100.625 MHz . The design had been optimized to get a rather short structure with LRFQ=3.1 m with moderate electrode voltages of UQ = 70 kV. The resonant insert has a cooled base plate and solid stems and vane-electrodes. The mechanical design is very stiff, with a precise base-structure. The top lid along the RFQ allows installation, alignment, inspection and maintenance. After the mechanical alignment of the electrodes the longitudinal electrode voltage distribution will be adjusted with tuning plates between the stems. The properties of the RFQ, the results of the tuning and the status of the project will be discussed.
DAE/VECC, Calcutta
Radio Frequency Quadrupole (RFQ) would be the first post accelerator for the upcoming Rare Isotope Beam (RIB) facility at Variable Energy Cyclotron Centre (VECC), India. A 33.7 Mhz RFQ capable of accelerating stable as well as RI beams of q/A > 1/16 to about 30 keV/u has already been constructed and operational since September 2005 . This has been installed in a dedicated beam line for doing material science experiments. Another 3.4 m long RFQ resonating at 37.6 Mhz and capable of accelerating heavy ion beams up to 98 keV/u have been fabricated which is to be installed in the beam line for the VEC-RIB facility. The physical parameters,rf test along with the measurements of accelerated beams from RFQ would be presented.
INFN/LNL, Legnaro, Padova
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova
The IFMIF-EVEDA (Engineering Validation and Engineering Design Activities) project foresees the construction of a high intensity deuteron accelerator up to 9 MeV, with the characteristics required for the actual IFMIF facility. The linac will be installed in Rokkasho, and INFN is in charge of the construction of a 5 MeV, 125 mA, deuteron RFQ operating at 175 MHz. In this article the beam dynamics design of this challenging RFQ is described, namely the design, the main outcomes in terms of beam particles physics, and finally the study of mechanical and rf field error tolerances. The RFQ design method has been aimed to the optimization of the voltage and R0 law along the RFQ, the accurate tuning of the maximum surface field and the enlargement of the acceptance in the final part of the structure. As a result this RFQ is characterized by a length shorter than in all previous design, very low losses (especially at higher energy) and small rf power dissipation.
INFN/LNL, Legnaro, Padova
Università degli Studi di Milano, Milano
The RFQ of IFMIF-EVEDA project is characterized by very challenging specifications, with 125 mA of deuteron current accelerated up to 5 MeV. Upon beam dynamics studies, it has been chosen a law for the variation of R0 and voltage along the structure; this law provides a significant reduction in terms of structure length, beam losses and rf power consumption. Starting from these outcomes, the rf study of the RFQ, aimed at determining the optimum design of the cavity shape, was performed. The stabilization issues were also addressed, through the analysis of the RFQ sensitivity to geometrical errors, by means of perturbative theory-based algorithms developed for this purpose . Moreover the determination of the main 3D details of the structure was also carried out. In this article the results of the rf studies concerning the above-mentioned topics are outlined.
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova
INFN/LNL, Legnaro, Padova
CERN, Geneva
The Legnaro National Laboratory (LNL) is building the 30 mA, 5 MeV front end injector for the production of intense neutron fluxes for interdisciplinary application. This injector comprises a proton source, a low energy beam transport line (LEBT), a radio frequency quadrupole (RFQ) and a beam transport line designed to provide a 150 kW beam to the berillium target used as neutron converter. The RFQ, developed within TRASCO project for ADS application, is designed to operate cw at 352.2 MHz. The structure is made of OFE copper and is fully brazed. The RFQ is built in 6 modules, each approximately 1.2 meter long. This paper covers the mechanical fabrication, the brazing results and acceptance tests for the various modules.
RLNR, Tokyo
In order to obtain high intensity ion beams from a linear accelerator (linac) stably, it is necessary to suppress the defocusing force due to the space charge effect. The defocusing force is extremely strong in low energy and high intensity beams. Therefore, high intensity ion beam acceleration in the low energy region is one of the most difficult conditions to achieve. One of the solutions is the relaxation of the defocusing force by dividing the high intensity beam into several beams. Thus, a multibeam IH type Radio Frequency Quadrupole (IH-RFQ) linac has been proposed for a high intensity injector system. In particular, we have been developing a two-beam type IH-RFQ cavity as a prototype of the multibeam type IH-RFQ by using computer code. This prototype has the capability of accelerating charged particles to mass ratio (q/A) greater than 1/6 from 5 keV/u up to 60 keV/u. The expected total output current is 87.2 mA for the total input beam current of 120 mA.
CERN, Geneva
CEA, Gif-sur-Yvette
The first stage of acceleration in Linac4, the new 160 MeV CERN H- injector, is a 352 MHz, 3 m long Radiofrequency Quadrupole (RFQ) Accelerator. The RFQ will capture a 70 mA, 45 keV beam from the rf source and accelerate it to 3 MeV, an energy suitable for chopping and injecting the beam in a conventional Drift Tube Linac. Although the RFQ will be initially operated at low duty cycle (0.1%), its design is compatible with higher duty cycle (10%) as the front-end for a possible high-intensity upgrade of the CERN linac facility. The RFQ will be of the brazed-copper design and will be built and assembled at CERN. Beam dynamics design allows for a compact structure made of a single resonant unit. Field symmetry is ensured by fixed tuners placed along the structure. In this paper we present the rf and mechanical design, the beam dynamics and the sensitivity to fabrication and to rf errors.
Fermilab, Batavia
ANL, Argonne
Fermilab is designing and building the HINS front-end test facility. The HINS proton linear accelerator consists of a normal-conducting and a superconducting section. The normal-conducting (warm) section is composed of an ion source, a 2.5 MeV radio frequency quadrupole (RFQ), a medium energy beam transport, and 16 normal-conducting crossbar H-type cavities that accelerate the beam to 10 MeV. Production of 325 MHz 4-vane RFQ is recently completed. This paper presents the design concepts for this RFQ, the mechanical design and tuning results. Issues that arose during manufacturing of the RFQ will be discussed and specific corrective modifications will be explained. The preliminary results of initial testing of RFQ at the test facility will be presented and comparisons with the former simulations will also be discussed.
Fermilab, Batavia
Similar to many other linear accelerators, the High Intensity Neutron Source requires an RFQ for initial acceleration and formation of the bunched beam structure. The RFQ design includes two main tasks: a) the beam dynamics design resulting in a vane tip modulation table for machining and b) the resonator electromagnetic design resulting in the final dimensions of the resonator. The focus of this paper is on the second task. We report complete and detailed rf modeling on the HINS RFQ resonator using simulating codes CST Microwave Studio (MWS) and Ansoft High Frequency Structure Simulator (HFSS). All details of the resonator such as input and output radial matchers, the end cut-backs etc. have been precisely determined. Finally in the first time a full size RFQ model with modulated vane tips and all tuners installed has been built, and a complete simulation of RFQ tuning has been performed. Comparison of the simulation results with experimental measurements demonstrated excellent agreement.
Fermilab, Batavia
Recently high power tests of the room temperature cross-bar H-type resonators (CH resonators) and high gradient tests of a superconducting single spoke resonator (SSR) have been performed under the High Intensity Neutrino Source (HINS) project at Fermilab. The resonators have shown a tendency of having multipacting at various levels of input power and therefore longer processing time. To provide insights for the problem, detailed numerical simulations of multipacting for these resonators have become necessary. New generation of accelerating structures like superconducting spoke resonators and room temperature CH resonators need a full 3D treatment. Simulations and study of multipacting in the resonators have been carried out using CST Particle Studio. The problematic regions and power levels have been identified for both types of resonators. This presentation will give the result of simulations and comparison with experimental data.
BNL, Upton, Long Island, New York
Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
Direct injection scheme was proposed in 2000 at RIKEN in Japan. The first beam test was done at Tokyo Institute of Technology using a CO2 laser and an 80 MHz 4 vane RFQ in 2001, and further development continued in RIKEN. In 2006, all the experimental equipment was moved to BNL and a new development program was started. We report on our recent activities at BNL including the use of a frozen gas target for the laser source, low charge state ion beam production and a newly developed laser irradiation system.
BNL, Upton, Long Island, New York
Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
Direct plasma injection scheme has been developed recently for producing and accelerating intense pulsed heavy ion beams with high charge states. This new method uses a combination of a laser ion source and an RFQ linear accelerator and its repetition rate is determined by the laser system. Fixed field alternating gradient (FFAG) accelerator is being focused as a high repetition synchrotron. An integration of these new techniques enables one to produce a large beam power with heavy ion beams. At Ito campus of Kyushu University, a proton FFAG is being installed. We propose to construct a new injector linac for the FFAG. The planned operating parameters are 100 Hz repetition rate, 20 mA of fully stripped carbon beam and 200 MHz operating frequency for the linac.
GSI, Darmstadt
A dedicated charge separator system is now installed in the transfer line to the GSI-synchrotron SIS18. In former times charge separation was performed with a single 11 degree dipole magnet after a 25 m beam transport section. This was not adequate to meet the requirements during high current operation for FAIR: it only allows for charge state separation of low intensity and low emittance beams. With the new compact charge separator system emittance blow up and unwanted beam losses for high intensity beam operation will be avoided. Additionally a new beam diagnostics test bench is integrated. With this the beam parameters (ion current, beam profile, beam position, transversal emittance, bunch structure and beam energy) for the injection into the SIS18 can be measured in parallel to the routine operation in the transfer line. Results of the commissioning with high intensity argon beams as well as with an uranium beam will be reported.
IHEP Beijing, Beijing
In the China Spallation Neutron Source (CSNS) linac, a conventional 324 MHz drift-tube linac (DTL) accelerating an H- ion beam from 3 MeV to 132 MeV has been designed with 1.05% duty, consisting of 7 tanks with a total length of approximately 59.6 m. Currently, R&D work has focused on Tank 1, which will have 61 drift-tubes (DT) each housing an electro-magnet quadrupole (EMQ). Some EMQs with SAKAE coil have been fabricated and are under rigorous magnetic measurements by means of Hall probe, single stretched wire, rotating coil in order to verify the design specifications and fabrication technology. Magnetic measurements on the EMQs with iron cores made from the electrical-discharge machining (EDM) and the stacking method will be compared and discussed. Work has been implemented to reduce the alignment discrepancies between the geometric center of the DT and magnetic center of EMQ to within ± 50 μm.
IHEP Beijing, Beijing
A conventional 324 MHz DTL has been designed for China Spallation Neutron Source (CSNS) to accelerate H- ion from 3 MeV to 132 MeV. There are 7 tanks in the DTL and currently the R&D of tank-1 is under proceeding. In our design, Tank-1 has a tilt field distributed partially in order to obtain most effective energy gain and low Kilpatric parameter. The tank has been fabricated and the manufacture technique was verified by the measurement results. Because of the difficulty of tuning a partial tilt field distribution, a complex rf measuring and tuning procedure are introduced. The analysis on calculating the perturbation in a new method is also proposed.
CERN, Geneva
INFN/LNL, Legnaro, Padova
The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H- ion beams of up to 40mA average pulse current from 3 to 50MeV. It is designed to operate at 352.2MHz and at duty cycles of up to 10%, if required by future physics programmes. The accelerating field is 3.2MeV/m over the entire length. Permanent magnet quadrupoles are used as focusing elements. The 3 DTL cavities consist of 2, 4 and 4 segments of about 1.8m each, are equipped with 35, 41 and 29 drift tubes respectively, and are stabilized with post-couplers. Several new features have been incorporated in the basic design. The electro-magnetic design has been refined in order to reduce peak field levels in critical areas. The mechanical design aims at reducing the complexity of the mechanical structure and of the adjustment procedure. Drift tubes and holders on the tanks that are machined to tight tolerances do not require adjustment mechanisms like screws or bellows for drift tube positioning. A scaled cold model, an assembly model and a full-scale prototype of the first half tank have been constructed to validate the design principles. The results of metrological and rf tests are presented.
NSC/KIPT, Kharkov
Experiments with heavy ion beams accelerated to an energy of 8.5 MeV/u as well as the work at developing new methods of acceleration and upgrading of accelerating structures are carried on at the Kharkov heavy-ion linear accelerator MILAC. The accelerating H-type structure with drift tubes of interdigital type (IH-structure) has been introduced in the main section and two pre-stripping sections of the MILAC accelerator. New original methods of tuning developed at MILAC have enabled the formation of uniform distribution of the accelerating field along the whole length of the accelerating structure. The introduction of IH accelerating structures of various modifications at the MILAC accelerator substantially extends the scientific and applied ranges of research. It involves experimental studies with heavy ions beams for production of track-etched membranes, generation of unique radionuclides, developments of proton and ion therapy, studies of radiation characteristics of constructional materials for nuclear engineering, investigations into the processes of fusion-fission of superheavy nuclei, and many other problems of nuclear physics.
Fermilab, Batavia
Funding: Fermi Research Alliance under contract with the US Department of Energy
In response to increasing beam intensity demands, the Fermilab 400 MeV Linac is operating at high intensity and higher repetition rates than were imagined when it was designed. This is happening at a time when maintenance time is at a premium. This has had an effect on Linac operation, tuning and reliability. Changes in tuning and equipment being made to accommodate the current running scenario along with reliability data will be presented.
TRIUMF, Vancouver
The ISAC superconducting linac is a fully operational machine that routinely provides beam to experiments. The linac consists of twenty superconducting independently phased cavities housed in five cryomodules. The initial tune is done manually aided by MATLAB routines to phase the linac and set the correct optics. From the initial tune we calculate the gradient at which each cavity operates based on the energy gain, the transit time factor and the geometry of the cavity itself. Then in the event of a gradient change of one or more cavities we can calculate the rf phase shift of each downstream cavity using the initial gradients, the known geometry of the entire linac and assuming linearity of the rf controls. This possibility has been investigated and we have demonstrated that the calculated phase shift can be implemented automatically thus avoiding a complete retune of the machine. In this paper we will present the calculations and the results of the online tests.
GANIL, Caen
CEA, Gif-sur-Yvette
LPSC, Grenoble
IPN, Orsay
The SPIRAL2 superconducting linac is composed of 2 cryomodule families, basically one of low beta, called Cryomodule A, and one of high beta, called Cryomodule B. The low beta family is composed of 12 single cavity cryomodule. The high energy section is composed of 7 cryomodules hosting 2 cavities each. According to beam dynamics calculations all the cavities will operate at 88 MHz: one family at beta=0.07, and one at beta=0.12. The design goal for the accelerating field Eacc of the SPIRAL2 QWRs is : 6.5 MV/m. The configuration, cavities and cryomodule tests and status and the foreseen linac tuning will be described.
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova
INFN/LNL, Legnaro, Padova
The superconducting linac ALPI, injected either by a XTU tandem or by the superconducting RFQ of PIAVE, is composed by 3 cryostats of bulk Nb cavities (β=0.056) and 13 cryostats of Nb sputtered on Cu cavities (β=0.11 and β=0.13), for a total of 64 cavities and an equivalent voltage of 35MV. The linac is build up in two branches connected by an achromatic and isochronous U-bend. In January 2007 a stripping station equipped with carbon foils of different thickness was placed after 6 cryostats, before the U-bend, to test the feasibility of acceleration and transport of a charge enhanced beam. The study was performed with 4 different beams (Ca, Ar, Zr and Xe) and a complete data analysis has been carried out.
CERN, Geneva
As part of the upgrade of the LHC injector complex at CERN, the construction of a 4 GeV Superconducting Proton Linac (the SPL, in fact an H- accelerator) is planned to begin in 2012. Depending upon physics requests, it should be upgradeable to 5 GeV and multi-MW beam power at a later stage. The construction of Linac4, its low energy front end, has started at the beginning of 2008. A full project proposal with a cost estimate for the low power version of the SPL aimed at improving LHC performance has to be ready for mid-2011. As a first step towards that goal, essential machine parameters like rf frequency, cooling temperature and beam current have recently been revisited and plans have been drawn for designing and testing critical components. The SPL parameters are reviewed in the context of the CERN plans for upgrading the LHC injectors, and the foreseen developments during the next years are described.
NSCL, East Lansing, Michigan
The Re-accelerator being developed at the Michigan State University is a major component of a novel system proposed at the NSCL to first stop the high energy RIBs by the in-flight particle fragmentation method in a helium filled gas system, then increase their charge state with an Electron Beam Ion Trap (EBIT) charge breeder, and finally re-accelerate them to about 3 MeV/u, in order to provide opportunities for an experimental program ranging from low-energy Coulomb excitation to transfer reaction studies of astrophysical reactions. The accelerator system consists of a Low Energy Beam Transport (LEBT) with an external multi-harmonic buncher, a radio frequency quadrupole (RFQ) followed by a superconducting linac and a High Energy Beam Transport (HEBT). The superconducting linac will use quarter-wave resonators with bopt of 0.047 and 0.085 for acceleration and superconducting solenoid magnets for transverse focusing. The paper will discuss the recent progress of R&D and beam dynamics studies for the MSU Re-accelerator.
GSI, Darmstadt
HIT, Heidelberg
A clinical facility for cancer therapy using energetic proton and ion beams (C, He and O) has been installed at the Radiologische Universitätsklinik in Heidelberg, Germany. It consists of two ECR ion sources, a 7 MeV/u linac injector, and a 6.5 Tm synchrotron to accelerate the ions to energies of 430 MeV/u. The linac comprises a 400 keV/u RFQ and a 7 MeV/u IH-DTL operating at 216.8 MHz and has been commissioned successfully in 2006. Yet the overall achieved transmission through the injector linac did not exceed 30% due to a mismatch of the beam at the RFQ entrance. Thus a detailed upgrade programme has been started to exchange the RFQ with a new radial matcher design, to correct the alignment and to optimize beam transport to the IH-DTL. The aim is to achieve a sufficient linac transmission above 60%. The new design of the RFQ has been finished in 2007 and the RFQ is currently in production. A test bench comprising a full ion source and LEBT setup to commission the RFQ in 2008 is under construction at Danfysik in Danemark. The current status of this upgrade programme will be reported in this contribution.
RLNR, Tokyo
U. Sapientia, Targu Mures
BNL, Upton, Long Island, New York
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
We succeeded to accelerate very intense carbon ions with the Direct Plasma Injection Scheme (DPIS) using Laser ion source in 2001 and 2004. The peak current reached more than 60 mA of C4+ and 18 mA of C6+ with pulse width of 2-3 x 10-6 sec. We believe that these techniques are quite effective for pulse accelerator complexes such as linear accelerator and synchrotron (heavy-ion cancer therapy). In heavy cancer therapy, carbon stripper section is rejected by accelerated C6+. One turn injection of high intensity (6 mA) C6+ ion is possible to enough in synchrotron. We study a new hybrid single cavity linac combined with radio frequency quadrupole (RFQ) electrodes and drift tube(DT) electrodes into a single cavity. The hybrid linac is able to downsize the linac system and reduce the peripheral device. Using DPIS with Laser ion source, we study POP hybrid single-cavity accelerator of C6+ for injector linac of C cancer therapy. The linac is designed to accelerate 6 mA C6+ ion from 40 keV/u to 2 MeV/u with YAG Laser ion source. We will present the design procedures of this hybrid linac, which is based on a three-dimensional electromagnetic field and particle orbit calculation.
Kyoto ICR, Uji, Kyoto
JAEA/Kansai, Kizu-machi Souraku-gun Kyoto-fu
JAEA, Ibaraki-ken
NIRS, Chiba-shi
Funding: This work is supported by Advanced Compact Accelerator project by MEXT of Japanese Government and 21COE of Kyoto University, Center for Diversity and Universality in Physics.
By the phase rotation with the use of rf electric fields created by two gap resonator synchronous to a pulse laser, the energy spread of the laser-produced ions can be reduced*. In addition, owing to the curved structure of the electric field line in the gaps of the phase rotator, radial focusing effect is found also to exist. In order to extend the applicable energy of the phase rotation to the region where such laser produced protons can be directly applied for cancer therapy, multi-gap resonator with higher frequency has been proposed. By controlling the relative phases between the pulse laser and the electric fields in the gaps of phase rotator, we can create peaks in the energy spectrum simultaneously focusing in the radial direction.
* Japanese Journal of Applied Physics (Express Letter), 46 (2007) L717-L720
NIIEFA, St. Petersburg
AN Krylov SRI, St. Petersburg
Funding: Rosatom corp.
There are examined prospects and challengers associated with the development of low-energy electronuclear power plant eliminating any possibility of uncontrolled chain fission reaction through fission in subcritical reactor with an additional neutron source. The neutron source is anticipated to be a heavy-element target irradiated with a beam of protons accelerated to several hundreds of mega-electron-volts. The intensity of external neutron source for an electronuclear reactor rated under 200-400 MW may be much less than for greater ones, and that allows reducing accelerator performances to limits that are already run in the world industry. Potential applications of such electronuclear plants include municipal, industrial and other electricity, and heat supply utilities in remote areas. The same engineering philosophy may be used on solving of the nuclear waste transmutation problem.
Linac Systems, LLC, Albuquerque, New Mexico
A 2.5 MeV, 20 mA, cw, proton linac for the Boron Neutron Capture Therapy medical application is under construction at Linac Systems. The system consists of a 25 keV microwave ion source, a solenoid lens based low energy beam transport system, a 0.75 MeV RFQ linac, a 2.5 MeV RFI linac, and the necessary service systems. Because of the superb low energy capabilities of the RFI structure, the RFQ linac need only go to 0.75 MeV, resulting in a cavity dissipation of 74 kW for the RFQ section. Because of the high rf efficiency of the RFI structure, the cavity dissipation is only 35 kW for the RFI section. Extensive thermal studies have been made to accommodate these cw heat load. The beam power is 50 kW. The rf power system is designed for an average power output of 200 kW. The RFQ and RFI sections are coupled into a single resonant unit by a quarter-wave-stub resonant coupler. The combination is driven at a single point in the RFQ structure. The total length of the linac is 2.6 meters. The system is scheduled for completion by early fall (2008).
Linac Systems, LLC, Albuquerque, New Mexico
A 50 kW, water-cooled conical target for producing neutrons via the Li-7(p,n)Be-7 reaction at 2.5 MeV proton energy is under development at Linac Systems. This target is intended to accept a stationary, expanded CW beam with a diameter of 8 cm directly from an rf linac, resulting in peak surface heat flux of 7.5 MW m-2 (a 'waterbag' beam power distribution is assumed). The target is predicted to meet the intensity requirements for practical accelerator-based boron neutron capture therapy (BNCT), in concert with Linac Systems' CW RFI linac. Lithium metal targets present well-known physical and mechanical challenges at high beam power density that are addressed in our design. For instance, lithium melts at 180 C, necessitating efficient removal of heat at a low ΔT relative to ambient temperature. CFD modeling indicates that with 50 kW incident beam power, the peak lithium temperature can be held below 150 C with a water flow rate near 80 l min-1 and corresponding pressure drop of 170 kPa. The target prototype has been fabricated and is undergoing experimental thermal-hydraulic testing using an electron beam at the Plasma Materials Test Facility, Sandia National Laboratory.
Imperial College of Science and Technology, Department of Physics, London
The COMET experiment beamline uses bent solenoids for the muon transport and the spectrometer used to analyse the decay electrons from stopped muons. The bent solenoid includes not just a solenoid field but also a vertical dipole field. It is therefore important to have the ability to tune the field distribution. However, since the field distribution is mainly determined by the geometry it is difficult to adjust once the solenoids have been constructed. A cost effective method to provide tuning capability of the field distribution of the bent solenoids is proposed and the results of simulations presented.
IIT, Chicago, Illinois
Illinois Institute of Technology, Chicago, Illinois
LBNL, Berkeley, California
Funding: This work was partially supported by the Office of Science, U. S. Department of Energy, under Contract No. DE-AC02-05CH11231.
A key unanswered question in particle physics is why the universe consists only of matter. It is believed that CP violation in the lepton sector is the answer. The best tool to find this is a muon-based Neutrino Factory. Muons can also be used for an energy-frontier collider that would fit on an existing laboratory site. Since muons are produced as a tertiary beam, their phase space and energy spread are large and must be reduced (cooled) to create a usable beam. Ionization cooling, comprising momentum loss in material followed by rf reacceleration, is the only suitable technique. A cooling channel is merely a linac with absorbing material in the beam path. To demonstrate an understanding of the physics and technology issues, MICE will test a section of cooling channel exposed to a muon beam derived from the ISIS synchrotron at RAL. The muon beam line is now installed and commissioning is under way. Fabrication of cooling channel components and the required detector systems has begun and will be described. A successful demonstration will go a long way toward proving the value of muon beams for future accelerator-based particle physics experiments.
ANL, Argonne
Euclid TechLabs, LLC, Solon, Ohio
Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Dielectric loaded wakefield structures are being developed to be used as high gradient accelerator components. The high current electron beam at the Argonne Wakefield Accelerator Facility was used to excite wakefields in cylindrical dielectric loaded wakefield structures in the frequency range of 8 to 14 GHz, with pulse duration of a few nanoseconds. Short electron bunches (13 ps FWHM) of up to 86 nC drove these wakefields, and accelerating fields as high as 100 MV/m were reached. These standing-wave structures have a field probe near the outer edge of the dielectric to sample the RF fields generated by the electron bunches. Monitoring of the field probe signal serves to verify the absence of electric breakdown. Similar structures were used to extract RF power from the electron beam; however, in this case they were travelling-wave structures, driven by electron bunch trains of up to 16 bunches. RF pulses of up to 40 MW were measured at the output coupler of these structures.
UCLA, Los Angeles, California
BNL, Upton, Long Island, New York
SLAC, Menlo Park, California
USC, Los Angeles, California
Funding: Work Supported by US Department of Energy
In the plasma wakefield accelerator (PWFA), high quality accelerated electron bunches can be produced by injecting a witness bunch behind a single drive bunch or a train of N bunches. To operate at large gradient the plasma density must be in the 1017/cc range, corresponding to a typical bunch separation of the order of the plasma wavelength or ≈100μm. We have demonstrated that such a sub-picosecond temporal bunch structure can be produced using a mask to selectively spoil the emittance of temporal slices of the bunch*. The bunches spacing, as well as their length can be tailored by designing the mask and choosing the beam parameters at the mask location. The number of bunches is varied by using an adjustable width energy limiting slit. The bunches spacing is measured with coherent transition radiation interferometry. Experimental results will be presented and compared to simulations of the bunch train formation process with the particle tracking code ELEGANT.
*P. Muggli et al., to appear in Phys. Rev. Lett. (2008).
CEA, Bruyeres-le-Chatel
A 15 MeV accelerator scheme based on a dc photo-injector and a rf superconducting linac as been proposed as a new facility for radiography applications. The overall beam dynamics simulation process based on SUPERFISH and PARMELA codes will be reviewed. We present the results for the following beam operating conditions; acceleration of limited number of bunches, up to twenty electron micro-pulses of 100 ps time duration and 200 nC bunch charge, at 352 MHz repetition rate.
GANIL, Caen
IPN, Orsay
CEA, Gif-sur-Yvette
After a detailed design study phase (2003-2004), the SPIRAL2 project at GANIL (Caen, France) was officially approved in May 2005, and is now in its phase of construction, with a project group including the participation of many French laboratories (CEA, CNRS) and international partners. The SPIRAL2 facility is composed of a multi-beam driver accelerator (5 mA/40 Mev deuterons, 5 mA/33 Mev protons, 1 mA/14.5 M ev/u heavy ions), a dedicated building for the production of Radiactive Ion Beams, the existing cyclotron CIME for the post acceleration of the RIBs, and new experimental areas. In this presentation we focus on the beam dynamics studies dedicated to the SPIRAL2 accelerator part of the project, from the ECR sources to the High Energy Beam Lines which have been recently updated. Various tuning examples will be presented for a variety of ions at different final energies, including error studies and beam losses evaluation. Accent is also put on the way we tune the accelerator with the computing code TRACEWIN, by using 3D electromagnetic maps and diagnostics corresponding to the real machine.
CEA, Gif-sur-Yvette
The purpose of the IFMIF-EVEDA (International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities) demonstrator is to accelerate a 125 mA cw deuteron beam up to 9 MeV. Therefore, the project requires that the ion source and the low energy beam transport (LEBT) line deliver a 140 mA cw deuteron beam with an energy of 100 keV and an emittance of 0.25 π .mm.mrad (rms normalized) at the entrance of the RFQ. The deuteron beam is extracted from a 2.45 GHz ECR source based on the SILHI design*. A LEBT with a two solenoids focusing system is foreseen to transport and adapt the beam for the RFQ injection. In order to validate the LEBT design, intensive beam dynamics simulations have been carried out using a parallel implementation of a particle-in-cell 3D code which takes into account the space charge compensation of the beam induced by the ionisation of the residual gas. The simulations results (in particular from the emittance growth point of view) performed under several conditions of gas species or gas pressure in the beam line are presented.
*R. Gobin et al, Rev. Sci. Instrum. 79, 02B303 (2008).
CEA, Gif-sur-Yvette
INFN/LNL, Legnaro, Padova
CIEMAT, Madrid
One major subsystem of IFMIF (International Fusion Materials Irradiation Facility) is its accelerator facility, consisting of two 175 MHz CW accelerators, each accelerating a deuteron beam of 125 mA to the energy of 40 MeV. This high power beam, 10 MW, induces challenging issues that lead to plan a first phase called EVEDA (Engineering Validation and Engineering Design Activity), where only the portion up to 9 MeV of one accelerator will be constructed and tested. For these accelerators, the Parameter Design phase is about to be completed. This paper presents the status of these studies. Due to the very high beam intensity, particular efforts have been dedicated to minimise the space charge effect that can strongly increase the beam size via the halo, and the losses that can prohibit the requested hand-on maintenance. For that, Beam Dynamics simulations have been performed with 106 macro-particles, and a great vigilance has been granted to the emittance growth and the particles on the beam edge. Several possible solutions are presented, for which advantages and drawbacks to fulfil the specifications are discussed.
LAL, Orsay
A growing number of experiments require low emittance ultra-short electron bunches in the 100 fs range (rms value) for the production of coherent light or the injection in plasma for laser-plasma acceleration. Especially in the last case it is highly desirable to have a compact accelerator; hence a strong experimental activity is carried out to get such a beam directly from a photo-injector. We have performed beam dynamic simulations using the PARMELA code to study the performances of the alphaX photo-injector installed in the University of Strathclyde in UK. This rf gun is aimed to produce electron bunches of 100 pC bunch charge, 100 fs bunch length and 1 mmmrad transverse emittance. We will show the results of systematic parametric studies as a function of charge and laser pulse duration as well as the natural evolution of the beam phase space as a function of the distance from the photo-cathode.
GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
CEA, Gif-sur-Yvette
Funding: CARE, contract number RII3-CT-2003-506395) European Community INTAS Project Ref. no. 06-1000012-8782
Transverse emittance growth along the Alvarez DTL section is a major concern with respect to the preservation of beam quality of high current beams at the GSI UNILAC. In order to define measures to reduce this growth appropriate tools to simulate the beam dynamics are indispensable. This paper is on benchmarking of three beam dynamics simulation codes, i.e. DYNAMION, PARMILA, and PARTRAN against systematic measurements of beam emittance growth for different machine settings. Experimental set-ups, data reduction, the preparation of the simulations, and the evaluation of the simulations will be described. It was found that the mean value of final horizontal and vertical rms-emittances can be reproduced well by the codes.
TEMF, TU Darmstadt, Darmstadt
TU Darmstadt, Darmstadt
Funding: This work was partially funded by DESY Hamburg and DFG (SFB 634).
At the Superconducting DArmstadter LINear Accelerator (S-DALINAC) a new 100 keV polarized electron source is currently being installed. Therefore, a new low energy injection concept has to be designed. One of the main components of the injector are a polarized electron source, an alpha magnet and a Wien filter used for spin rotation as well as various beam forming elements. Fast beam dynamics simulations can advantageously assist the design process because of the flexible parameter variations combined with nearly simultaneous solution responses. Based on the moment approach a fast tracking code named V-Code has been implemented at TEMF. In order to simulate the entire injector an alpha magnet model was added to the V-Code database of beam line elements. In this paper a summary of issues regarding the implementation complemented with simulation results will be provided.
INFN/LNL, Legnaro, Padova
Soreq NRC, Yavne
IPN, Orsay
CEA, Gif-sur-Yvette
TRIUMF, Vancouver
Funding: We acknowledge the financial support of the European Community under the FP6 "Research Infrastructure Action-Structuring the European Research Area" EURISOL DS Project Contract No. 515768 RIDS.
A 1 GeV, 5 mA cw superconducting proton/H- linac, with the capability of supplying cw primary beam to up to four targets simultaneously by means of a new beam splitting scheme, is under study in the framework of the EURISOL DS project which aims to produce an engineering-oriented design of a next generation European Radioactive beam facility. The EURISOL driver accelerator would be able to accelerate also a 100 muA 3He beam up to 2 GeV, and a 5 mA deuteron beam up to 200 MeV. The linac characteristics and the status of the beam dynamics studies will be presented.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
JAEA, Ibaraki-ken
KEK/JAEA, Ibaraki-Ken
In the design of the very high intensity proton beam of the J-PARC LINAC, precise control of transverse beam dynamics is extremely important for suppression of beam loss. We present results of transverse beam matching and orbit corrections. The linac has 7 matching sections, each of which consists of 4 quadrupole magnets and 4 wire scanners. At 5 matching sections, beam widths at wire scanners are designed to agree with each other. This condition is used in the newly developed algorithm of quadrupole field correction based on a transport model, XAL. Excellent matching performance has been achieved with mismatch factor less than 5% at beam current of 5 to 30 mA. Control of beam parameters from linac into RCS is important for RCS paint injection. Beam studies and comparison to a model have been performed with linac wire scanners combined with multi-wire proportional monitors in the injection line. Orbit corrections with dipole steering magnets based on XAL model have been performed. Orbit deviations were suppressed within 1 mm in horizontal and vertical directions in the whole linac. For these measurements, detailed comparisons to a multi-particle simulation will be shown.
Kyoto ICR, Uji, Kyoto
ILL, Grenoble
RIKEN, Wako, Saitama
KEK, Ibaraki
University of Tokyo, Tokyo
JAEA, Ibaraki-ken
Kyoto University, Kyoto
ICEPP, Tokyo
We are developing a modulating permanent magnet sextupole lens to focus pulsed cold neutrons. It is based on the extended Halbach configuration to generate stronger magnetic field. In order to adjust the strength, the magnet is divided into two nested co-axial rings, where the inner ring is fixed and the outer ring can be rotated. Synchronizing the modulation with neutron beam pulse suppresses the chromatic aberration. These devices largely improve the utilization efficiency of neutrons, which makes even small linac based neutron sources practical. We have fabricated a half-scale model and studied its strength, torque and temperature rise during the operation. The main causes of the temperature rise are eddy-current loss in the poles made of soft magnetic material in inner ring and hysteresis loss. A laminated structure reduced the eddy-current loss. The temperature rise was suppressed to about half of the former model. We now study their B-H curve to optimize the thickness of the sheet. Annealing of the material is supposed to reduce the hysteresis loss, which will be tested soon. The experimental results of very-cold neutrons focusing with the half-scale model are also described.
MEPhI, Moscow
RAS/INR, Moscow
A new computer code for 3D simulation of multipacting phenomenon in axisymmetric and non-axisymmetric rf structures is presented. The goal of the simulation is to determine resonant electron trajectories and electron multiplication in rf structure. Both SW and TW structures of normal- and superconductivity have been studied. Simulation results are compared with theoretical calculations and experimental measurements.
MEPhI, Moscow
ScanTech, Atlanta, Georgia
MSU, Moscow
Introscan, Moscow
Analysis of input coupler asymmetry influence on beam dynamics in superconducting cavities of Energy Recovery Linac (ERL) injector is presented. Both coaxial and waveguide, single and twin input couplers were analyzed. Using computer simulation electromagnetic fields distribution in accelerating cavity was obtained and recalculated to the transverse-kick to the bunch passing the coupler. Also calculation of external coupling was done. RTMTRACE code was adapted for particle beams dynamic simulation. Acceptable transverse emittance growth was achieved for twin-coaxial (4%) and waveguide (5%) input coupler designs.
NIIEFA, St. Petersburg
Saint-Petersburg State University, Saint-Petersburg
AN Krylov SRI, St. Petersburg
Funding: Rosatom corp.
We present results of calculations of the neutron generation processes in metal targets induced by protons with energies up to 1 GeV using GEANT4 framework. Results on the neutron yield in large targets and neutron generation as a function of target's dimensions are presented. Energy deposit in the target is also given. The obtained results are to be used for multiplying blanket ADS target design.
CERN, Geneva
CEA, Gif-sur-Yvette
Linac4 is a normal conducting H- linac to be built at CERN as a new injector to the PS Booster and later on as a front end of a Superconducting Proton Linac (SPL). The layout consists of a H- rf source, a magnetic LEBT, a RFQ (accelerating the beam from 45 keV to 3 MeV), a chopper line, a conventional Drift Tube Linac (from 3 MeV to 50 MeV), a Coupled Cavity Drift Tube Linac (from 50 MeV to 100 MeV) and a pi-mode structure (PIMS, from 100 to 160 MeV), all operating at a frequency of 352 MHz. End-to-end beam dynamics simulations have been carried out in parallel with the codes PATH and TRACEWIN to optimise the design and performance of the accelerator and at the same time to guarantee a cross-check of the results found. An extensive statistical campaign of longitudinal error studies (static and dynamic) was then launched for validation of the proposed design and to assess the maximum level of RF jitter/inaccuracies (in both phase and amplitude) the system can tolerate before beam quality at injection in the PS Booster - and later in the SPL- is compromised.
IPM, Tehran
University of Oslo, Oslo
CERN, Geneva
The aim of the CLIC Test Facility CTF3, built at CERN by an international collaboration, is to address the main feasibility issues of the CLIC electron-positron linear collider technology by 2010. One key-issue studied in CTF3 is the generation of the very high current drive beam, used in CLIC as the rf power source. It is particularly important to simulate and control the drive beam longitudinal dynamics in the drive beam generation complex, since it directly affects the efficiency and stability of the rf power production process. In this paper we describe the ongoing effort in modelling the longitudinal evolution of the CTF3 drive beam and compare the simulations with experimental results.
Imperial College of Science and Technology, Department of Physics, London
University of Warwick, Coventry
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
In order to contribute to the development of high power proton accelerators in the MW range, to prepare the way for an ISIS upgrade and to contribute to the UK design effort on neutrino factories, a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. The results of numerical simulations of the particle dynamics from the charge separation dipole behind the ion source to the end of the MEBT will be presented. Previous measurements showed that the emittance of the beam delivered by the ion source exceeded our expectations by more than a factor of 3. Since then various changes in the beam extraction/post accelerator region reduced the beam emittance by a factor of 2. Simulations of the particle dynamics in the FETS based on distributions gained from recent measurements of the transversal beam emittance behind the ion source will be presented and the results for different input distributions discussed.
UMAN, Manchester
Higher order modes (HOMs) are simulated with finite element and finite difference computer codes for the ILC superconducting cavities currently under investigation for the ILC. In particular, HOMs in KEK's Ichiro type of cavity and Cornel University's Re-entrant design are focussed on in this work. The aim, at these Universities and laboratories, is to achieve an accelerating gradient in excess of 50 MV/m in 9-cell superconducting cavities whilst maintaining a high quality and stable electron beam. At these high gradients, electrical breakdown is an important cause for concern and the wakefields excited by the energetic electron beams are also potentially damaging to the beam's emittance. Here we restrict the analysis to performing detailed simulations, on emittance dilution due to beams initially injected with realistic offsets from the electrical centre of the cavities and due to statistical misalignments of the cavities. We take advantage of the latest beam dynamics codes in order to perform these simulations.
UMAN, Manchester
The globalised scattering matrix (GSM) method provides an efficient means of obtaining the electromagnetic field in interconnected multi-cavity structures. In the proposed XFEL at DESY and the ILC facilities, energetic electron beams can readily excite higher order modes which if left unchecked can dilute the emittance of the beams. The GSM in conjunction with finite element modelling of the scattering matrices of the linac cavities is used to enable the characteristic eigenmodes to be rapidly obtained and the potential for trapped modes is investigated. This characteristic eigensystem allows the wakefield experienced by the beam to be analysed and the consequences on beam quality ascertained. The impact of fabrication errors on the transverse electromagnetic field and corresponding resonant frequencies of the modes is also explored in detailed simulations.
ANL, Argonne
ORNL, Oak Ridge, Tennessee
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC-02-06CH11357.
In an effort to simulate the SNS linac using the beam dynamics code TRACK and to benchmark the results against the recent commissioning data, we have started updating TRACK to support SNS-type elements such as DTL's and CCL's. After successfully implementing and simulating the DTL section of the SNS linac*, we have implemented the CCL section and the high energy superconducting (SC) section up to 1 GeV. Results from end-to-end simulations of the SNS linac using TRACK will be presented and compared to simulations using other codes and to the recent commissioning data.
*"First TRACK Simulations of the SNS linac", B. Mustapha et al., in Proceedings of Linac-06 Conference, Knoxville, Tennessee, August 21-25, 2006.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We present a Monte-Carlo method implemented in the code elegant for simulating Touschek scattering effects in a linac beam. The local scattering rate and the distribution of scattered particles can be obtained from the code. In addition, scattered particles can be tracked to the end of the beam line and the local beam loss rate and beam halo information recorded. This information can be used for beam collimation system design.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Intrabeam scattering (IBS) may become an issue for linac-based fourth-generation light sources such as X-ray free-electron lasers and energy recovery linacs (ERLs), both of which use high-brightness electron beams with extremely small emittance and energy spread. Any degradation of the extremely high beam quality could significantly reduce the X-ray performance. We present here a strategy first used in the code elegant for simulating IBS effects for high brightness linac beams. We also present an application to a possible ERL upgrade of the Advanced Photon Source.
Northern Illinois University, DeKalb, Illinois
Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University.
Numerical simulations of charged particle beams require an approximation to the particle distribution being simulated. Depending on the flavor of the N-body code, these approximations suffer from different computational difficulties. We briefly outline these difficulties, and present approximations to particle distributions using orthogonal functions. We discuss two different types of orthogonal functions, new in the context of beam simulations: wavelets and scaled Gauss-Hermite basis. On the wavelet side, we present the wavelet-based Poisson equation solver we recently devised for use in particle-in-cell beam simulations, and report on some important enhancements being implemented as a part of an ongoing project. On scaled Gauss-Hermite basis side, we report preliminary results in efficiently approximating discrete particle distributions in an orthogonal basis in which the corresponding potential and forces are directly and easily found from the expansion coefficients of the distribution. Finally, we discuss application of these particle distribution representations in simulation of coherent synchrotron radiation.
G.H. Gillespie Associates, Inc., Del Mar, California
A specialized software package has been developed that enables the rapid implementation of custom beam optics modules that run in the Particle Beam Optics Laboratory (PBO Lab). PBO Lab is a commercially available software application that supports a suite of accelerator codes for design, operations, and personnel education. The intuitive and easy-to-use graphic user interface (GUI) is largely responsible for the popularity of PBO Lab. The Open Architecture Software Integration System, or OASIS, builds upon the capability of PBO Lab to host a suite of different codes, and provides an innovative framework that allows users to readily integrate their own optics programs into PBO Lab. The OASIS GUI can be used to readily create new PBO Lab modules without writing or compiling any source code. OASIS has been used to develop several new modules for PBO Lab. This paper presents a summary of the OASIS framework and describes some of the features used in creating the new PBO Lab modules for several popular optics codes.
G.H. Gillespie Associates, Inc., Del Mar, California
A new graphic user interface (GUI) has been created for the PARMILA 2 program. PARMILA 2 is an advanced version of the historical PARMILA program originally developed to design and model drift tube linear (DTL) accelerators. PARMILA 2 expands upon that capability to support the design and simulation of coupled cavity linear (CCL) accelerator structures, coupled-cavity drift tube linac (CCDTL) structures, superconducting accelerator structures, as well as DTL structures and transport lines that can include magnetic, radiofrequency and electrostatic beam optics elements. The Open Architecture Software Integration System, or OASIS, has been used to develop a custom module for the PARMILA 2 program that runs along with a suite of other optics codes in the Particle Beam Optics Laboratory (PBO Lab). OASIS development tools were utilized to define the innovative GUI for the PARMILA 2 module. Existing PARMILA 2 executables, including Parmila.exe, Lingraf.exe and readdst.exe, have been implemented via GUI commands utilizing other OASIS tools without any compilation or linking required. This paper presents an overview of the PARMILA 2 module and illustrates some of the GUI features.
CLASSE, Ithaca, New York
BNL, Upton, Long Island, New York
CERN, Geneva
Evolution of short intense electron bunches passing through bunch-compressing beamlines is simulated using the UAL (Unified Accelerator Libraries) string space charge formulation. Excellent agreement is obtained with results obtained experimentally at CTF-II, the CERN "Compact Linear Collider'' test facility. The 40 MeV energy of these data is low enough for Coulomb and Biot-Savart forces to be important and high enough for coherent synchrotron radiation and centrifugal space charge forces to be important. UAL results are also compared with CSRtrack results for emittance growth in a 40 MeV 'standard' chicane. Vertical space charge forces are found to be important in this (low energy) case.
LANL, Los Alamos, New Mexico
NSTec, Los Alamos, New Mexico
Voss Scientific, Albuquerque, New Mexico
SAIC, Los Alamos, New Mexico
Funding: Work supported by USDOE under contract DE-AC52-06NA25396
The DARHT-II linear induction accelerator (LIA) accelerates a 2 kA electron beam to more than 17 MeV. The beam pulse has a greater than 1.5-microsecond flattop region over which the electron kinetic energy is constant to within 1%. The beam dynamics are diagnosed with 21 beam-position monitors located throughout the injector, accelerator, and after the accelerator exit, where we also have beam imaging diagnostics. I will discuss the tuning of the injector and accelerator, and I will present data for the resulting beam dynamics. Beam motion at the accelerator exit is undesirable for its application as a bremsstrahlung source for multi-pulse radiography of explosively driven hydrodynamic experiments. I will discuss the tuning procedures and other methods we use to minimize beam motion, and to suppress the beam-breakup (BBU) and ion-hose instabilities*.
*"Long-pulse beam stability experiments on the DARHT-II linear induction accelerator", Carl Ekdahl, et al., IEEE Trans. Plasma. Sci. Vol. 34, 2006, pp. 460-466.
LANL, Los Alamos, New Mexico
Funding: This work has benefited from the use of the LANSCE at LANL. This facility is funded by the US DOE and operated by LANS for NSSA under Contract DE-AC52-06NA25396. LA-UR-08-03585.
Tuning particle accelerators is time consuming and expensive, with a number of inherently non-linear interactions between system components. Conventional control methods have not been successful in this domain, and the result is constant and expensive monitoring of the systems by human operators. This is particularly true for the start-up and conditioning phase after a maintenance period or an unexpected fault. In turn, this often requires a step by step restart of the accelerator. Surprisingly few attempts have been made to apply intelligent accelerator control techniques to help with beam tuning, fault detection, and fault recovery problems. The reason for that might be that accelerator facilities are rare and difficult to understand systems that require detailed expert knowledge about the underlying physics as well as months if not years of experience to understand the relationship between individual components, particularly if they are geographically disjoint. This paper will give an overview about the research effort in the accelerator community that has been dedicated to the use of artificial intelligence methods for accelerator beam line tuning.
SLAC, Menlo Park, California
Funding: Work supported by DOE contract DE-AC02-76SF00515.
SLAC's Advanced Computations Department (ACD) has developed the first high-performance parallel Finite Element 3D Particle-In-Cell code, Pic3P, for simulations of rf guns and other space-charge dominated beam-cavity interactions. As opposed to standard beam transport codes, which are based on the electrostatic approximation, Pic3P solves the complete set of Maxwell-Lorentz equations and thus includes space charge, retardation and wakefield effects from first principles. Pic3P uses advanced Finite Element methods with unstructured meshes, higher-order basis functions and quadratic surface approximation. A novel scheme for causal adaptive refinement reduces computational resource requirements by orders of magnitude. Pic3P is optimized for large-scale parallel processing and allows simulations of realistic 3D particle distributions with unprecedented accuracy, aiding the design and operation of the next-generation of accelerator facilities. Applications to the Linac Coherent Light Source (LCLS) rf gun are presented.
SLAC, Menlo Park, California
UMAN, Manchester
The CLIC linear collider aims at accelerating multiple bunches of electrons and positrons and colliding them at a center of mass energy of 3 TeV. These bunches are accelerated through X-band linacs operating at an accelerating frequency of 12 GHz. Each beam readily excites wake-fields in the accelerating cavities of each linac. The transverse components of the wake-fields, if left unchecked, can dilute the beam emittance. The present CLIC design relies on heavy damping of these wake-fields in order to ameliorate the effects of the wake-fields on the beam emittance. Here we present initial results on simulations of the long-range wakefields in these structures and on beam dynamics simulations. In particular, detailed simulations are performed, on emittance dilution due to beams initially injected with realistic offsets from the electrical centre of the cavities and due to statistical misalignments of the cavities.
ORNL, Oak Ridge, Tennessee
GSI, Darmstadt
The 4ν=1 resonance of a linac is found when the depressed tune is around 90 deg. It is observed that this fourth order resonance is dominating over the better known envelope instability and practically replacing it. Simulation study shows a clear emittance growth by this resonance and its stopband. Experimental measurement of the stopband of this resonance is proposed and conducted in early 2008 using the UNILAC at GSI. This study will serve as a excellent benchmarking.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
For a high intensity linac such as the SNS linac, it matters to match adequately to minimize the beam mismatch and potential beam loss. The technique of doing the matching using the wire-scanners in series was employed. It was verified that matching was improved through the matching technique based on the beam profile measurements from wire-scanners in series.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The importance of a proper phase law is recognized to tune the synchronous phase of each superconducting cavities of a high intensity proton linac such as the SNS linac. The factors to be optimized are:
- maximizing the longitudinal acceptance
- better matching throughout the linac and
- achieving maximum beam energy.
Nihon University, Advanced Research Institute for the Sciences and Humanities, Funabashi
LEBRA, Funabashi
The 125 MeV linac at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University has been used for generation of the near-infrared FEL and the Parametric X-ray Radiation (PXR). Currently the FELs from 0.86 to 6 microns and the PXR X-rays from 5 to 20 keV are available at LEBRA. Precise experiments using the light sources require a high stability in both the wavelength and the intensity of the lights. Though the linac was operated with the cooling water stabilized at 30 plus or minus 0.2 deg C, periodical fluctuation of the electron beam energy and the beam orbit suggested that the stability of the cooling water temperature was not sufficient. With this condition a large fluctuation (plus or minus 15%) was observed for the PXR intensity. After the improvement of the fine cooling water system and the water flow path, fluctuation of the cooling water temperature at the supply head of the accelerating tubes and the electromagnets was suppressed to within plus or minus 0.01 deg C. As a result of the improvement the PXR intensity fluctuation at the X-ray output port has been suppressed to within plus or minus 2% for the operation over several hours.
Fermilab, Batavia
Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Fermilab* is constructing superconducting rf test facilities for development of technologies to be used in future Linac projects. Two of these facilities, the High Intensity Neutrino Source and the New Muon Laboratory, are proto-type Linacs which will run with beam. The requirements for these facilities vary but all involve collaboration and flexibility for integrating various new instruments. Tight timing requirements and automation are also required. Some facilities require integration into the existing Fermilab Control system. The controls also must be robust so as not to interfere with the main purpose of the facilities. We will outline the plan for accomplishing this task as well as the current status.
LANL, Los Alamos, New Mexico
Funding: This work supported by the US National Nuclear Security Agency and the US Department of Energy under contract DE-AC52-06NA25396
The Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) at Los Alamos National Laboratory is the world's most advanced weapons test facility. DARHT contains two linear accelerators for producing flash radiographs of hydrodynamic experiments. High-speed electronics and optical instrumentation are used for triggering the accelerators and collecting accelerator data. Efficient and effective diagnostics provide basic information needed to routinely tune the accelerators for peak radiographic performance, and to successfully monitor the accelerators performance. DARHT's server and network infrastructure is a key element in providing shot related data storage and retrieval for successfully executing radiographic experiments. This paper will outline the elaborate Data Acquisition, Archival, Analysis, and Instrument Control System (DAAAC), as well as the server and network infrastructure for both accelerators.
LA-UR-08-03265
LANL, Los Alamos, New Mexico
Funding: This work supported by the US National Nuclear Security Agency and the US Department of Energy under contract DE-AC52-06NA25396
The mission of the Dual Axis Radiograph Hydrodynamic Test (DARHT) Facility is to conduct experiments on dynamic events of extremely dense materials. The PSS control system is designed specifically to prevent personnel from becoming exposed to radiation and explosive hazards during machine operations and/or the firing site operation. This paper will outline the Radiation Safety System (RSS) and the High Explosive Safety System (HESS) which are computer-controlled sets of positive interlocks, warning devices, and other exclusion mechanisms that together form the PSS.