ORNL, Oak Ridge, Tennessee
Experience and lessons with the SNS superconducting linac over the first 5 years of commissioning and operation are reviewed. As the beam power was ramped up to 1 MW, the linac beam loss has been maintained below 1 W/m and residual activation has been held to a safe level. This can be attributed mainly to a robust accelerator design as well as to dedicated beam dynamics studies during this period. In addition to a review of both transverse and longitudinal beam phase-space measurements, we will review several hardware lessons learned with this high-power proton linac − such as nonlinear multipole components of the linac quadrupoles, beam collimators, high-order-mode couplers of the superconducting cavities, and cavity piezo tuners.
CEA, Gif-sur-Yvette
CIEMAT, Madrid
FZJ, Jülich
The IFMIF project aims to build a high intensity material irradiation facility which one of the main components is a high intensity deuteron accelerator. A prototype of this accelerator will be built in Rokkasho in Japan. It includes a cryomodule composed of 8 superconducting cavities (HWR) powered by 200 kW couplers to accelerate the deuteron beam from 5 MeV to 9 MeV. The beam is focused inside the cryomodule by 8 superconducting solenoids. The cryomodule design has to respect some severe beam dynamics requirements, in particular a restricted space for the component interfaces and an accurate alignment to be kept during cooling down. A double cryogenic system has been designed as it is necessary to control the cavity cooling independently from the solenoid one. The cryomodule design should also be compatible with its environment in the Rokkasho building. This paper gives then a general overview of the 1rst cryomodule current design and its interfaces. It defines the concept chosen for the Cryogenic System, explains the method foreseen for the assembly and alignment and describes the integration study in Rokkasho.
CEA, Gif-sur-Yvette
CIEMAT, Madrid
TTI, Santander
FZJ, Jülich
The driver of the International Fusion Material Irradiation Facility (IFMIF) consists of two 125 mA, 40 MeV CW deuteron accelerators. A superconducting option for the 5 to 40 MeV linac based on Half-Wave Resonators (HWR) has been chosen. The first cryomodule houses 8 HWR's supplied by high power RF couplers; each of them should be able to operate at 200 kW in CW. This paper will give an overview of the RF design of the 175 MHz CW power coupler. The detailled mechanical studies and the realization will be performed by the Industry. Global approach of the contract with the Industry and the organization of the intermediate validation tests will be discussed. In a second part, the choices and the last advances concerning the couplers RF power test stand will be described.
CEA, Gif-sur-Yvette
CIEMAT, Madrid
INFN/LNL, Legnaro (PD)
IFMIF/EVEDA, Rokkasho
Fusion for Energy, Garching
JAEA, Aomori
The objectives of the IFMIF/EVEDA project are to produce the detailed design of the entire IFMIF facility, as well as to build and test a number of prototypes, including a high-intensity CW deuteron accelerator (125 mA @ 9 MeV). Most of the accelerator components (Injector, RFQ, Superconducting RF-Linac, Transport Line and Beam Dump, RF Systems, Local control systems, beam instrumentation) are designed and provided by European institutions (CEA/Saclay, CIEMAT, INFN/LNL, SCK-CEN), while the RFQ couplers, the supervision of the control system and the building including utilities constructed at Rokkasho BA site are provided by JAEA. The coordination between Europe and Japan is ensured by an international project team, located in Rokkasho, where the accelerator will be installed and commissioned. The design and R&D activities are presented, as well as the schedule of the prototype accelerator.
CEA, Gif-sur-Yvette
CIEMAT, Madrid
FZJ, Jülich
In the framework of the International Fusion Materials Irradiation Facility (IFMIF), which consists of two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV, an accelerator prototype is presently under design for the first phase of the project. A superconducting option has been chosen for the 5 MeV RF Linac, based on a cryomodule composed of 8 low-beta Half-Wave Resonators (HWR), 8 Solenoid Packages and 8 RF couplers. This paper will focus on the HWR sub-system: the RF, thermo-mechanical design, and the realization of the first prototype of HWR will be presented. The resonator tuning frequency is controlled by an innovant Cold Tuning System (CTS), located in the central region of the cavity. The different options for tuning will be discussed and the final thermo-mechanical design will be detailed. First validation test results of the CTS are expected for the conference.
IAP, Frankfurt am Main
TU Darmstadt, Darmstadt
GSI, Darmstadt
StrahlSim is a unique code for the simulation of charge exchange driven beam loss and dynamic vacuum effects in heavy ion synchrotrons. Dynamic vacuum effects are one of the most challenging problems for accelerators using intermediate charge state, high intensity heavy ion beams (e.g. AGS Booster, LEIR, SIS18). StrahlSim can be used as a design tool for synchrotrons, e.g. for the estimation of pumping power needed to stabilize the dynamic vacuum. Recently, StrahlSim has been extended to simulate time dependent longitudinal pressure profiles. The new code calculates a self-consistent static pressure distribution along the accelerator and simulates local pressure rises caused by dynamic and systematic beam losses. StrahlSim determines the loss distribution of charge exchanged beam ions and respects the beam energy dependence of the charge exchange cross sections. The beam loss calculated by means of the new time dependent longitudinal pressure profiles has been benchmarked with measured data from the latest SIS18 machine experiments.
IAP, Frankfurt am Main
IKF, Frankfurt-am-Main
An intense 2 MeV, 200 mA proton beam will drive a neutron source by the reaction Li7(p,n)Be7 on solid as well as on liquid lithium targets. Actually, the facility is under construction at the physics faculty new experimental hall in Frankfurt. To study in detail the burning of elements in stars by the s-process, a pulsed beam operation with a bunch compressor at the linac exit will offer several Ampere beam current within 1 ns pulse length and with 250 kHz rep. rate at the n - production target. As the upper limit of generated neutrons and the total n- flux at this source are well defined the sample for neutron capture measurements can be placed after a time of flight path as short as 0.8 m only. This will provide highest accessible pulsed neutron flux rates for neutron energies in the 1 - 500 keV range. The highly space charge dominated bunch forming process as well as the ion source, the rf coupled 175 MHz RFQ/DTL - resonator and the target development will be explained.
INFN- Sez. di Padova, Padova
INFN/LNL, Legnaro (PD)
INFN-Torino, Torino
In the framework of the IFMIF/EVEDA project, the RFQ is a 9.8 m long cavity, with very challenging mechanicals specification. In the base line design, the accelerator tank is composed of 18 modules that are flanged together. The construction procedure of each module foresees the horizontal brazing of the four electrodes and then the vertical brazing of the flanges. A RFQ prototype, composed of 2 modules, aimed at testing all the mechanical construction procedure is under construction. In this article, the progress of the prototype construction and the progresses in the design and engineering phase, as well the description of all the fabrication phases is reported.
INFN/LNL, Legnaro (PD)
An important issue for high intensity RFQs (tenth of mA beam current and more) is the necessity of keeping the beam losses as low as possible, in order to allow reliable and safe maintenance of the machine. Typically, beam dynamics outcomes driven by these constraints result both in a RFQ length that is considerably higher than the wavelength and in an intra-vane voltage admitted variation with respect to the design value that must not exceed a few percent. Therefore an analytical tool is needed in order to foresee the effect of geometric perturbations on the voltage profile, in order to give an indication on the permitted ranges of geometrical errors in the RFQ construction. In this article a five conductors transmission line equivalent circuit for the four-vane RFQ is presented and the effects of geometrical perturbations on the voltage profile are analyzed in some particular cases. The case study is the IFMIF RFQ (125 mA deuteron current, 9.8 m length, 175 MHz frequency), whose features are particularly suitable for this kind of analysis.
KEK, Ibaraki
STFC/RAL/ISIS, Chilton, Didcot, Oxon
ANL, Argonne
Tsukuba University, Ibaraki
A low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by collaboration between Argonne National Laboratory (US), KEK (Japan) and Rutherford Appleton Laboratory (UK). The system has less than 30 Ω of output impedance over wide frequency range of 2.7-6.2 MHz. However, distortions of voltage waveform in the driver stage have been a long-standing issue. It was found such distortions were generated depending upon the higher-order-modes of the anode-choke impedance. In this report, method to realize the smooth sinusoidal waveform in the wideband system is presented.
KEK, Ibaraki
The J-PARC accelerator complex consists of a linear accelerator (330 m long, 181 MeV), a rapid cycling synchrotron (3 GeV RCS, 350 m circumference, 25 Hz) and a slow cycling synchrotron (MR, 30 GeV as a first step energy, 1600 m circumference, typically with 3.5 sec cycle). The RCS provides high intensity proton beam to the materials and life science facility and the MR. The MR has two beam extraction lines. One is a slow extraction system for the hadron physics, and other a fast extraction system for neutrino science. We have to challenge many issues to complete construction of the J-PARC accelerator facility on-schedule in 2008 despite all the hardships, such as the problems included in the original design, technology choices and fabrication procedure of the machine components, and construction of conventional facilities. As a first step of operation, we could commission all accelerator facilities and provide beam to all experimental facilities in 2009 successfully. We will report about analysis of these issues and how to solve them, which is a necessary step to realize the design beam power as a next step, and to challenge the future upgrade beyond the original design.
KEK/JAEA, Ibaraki-Ken
KEK, Ibaraki
JAEA/J-PARC, Tokai-mura
The Japan Proton Accelerator Complex includes the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main ring synchrotron (MR). Both synchrotrons use the high field gradient magnetic alloy (MA) loaded cavities. In RCS, 11 RF systems have been fully operational since December 2008. The RCS RF systems are operated with dual-harmonic acceleration voltages. Beam acceleration and bunch shape manipulation are efficiently taking place. 120kW of the neutron user operation was started at the Material and Life science facilities in November 2009. In MR synchrotron, the 5th RF system were installed in August 2009, and therefore 5 RF systems are now in operation. Beam commissioning for delivering protons to the hadron facility and neutrino beam experimental facility are under way. The neutrino user experiment is intended to start January 2010. Proton beam operation with more than 100kW is required. The approaches to realizing high intensity operation and the MR upgrade plan will be presented.
JAEA/LINAC, Ibaraki-ken
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
JAEA, Ibaraki-ken
KEK, Ibaraki
RAS/INR, Moscow
J-PARC, KEK & JAEA, Ibaraki-ken
The mass production of the ACS (Annular Coupled Structure) cavity started from March 2009 for the J-PARC Linac energy upgrade from 181 MeV to 400 MeV. This upgrade project requires 18 ACS accelerating modules and two debunchers additionally within three years. The construction schedule is so tight that we have to optimize the fabrication process. For example the geometrical beta is varied for each accelerating module, thus the several test cells were fabricated and for the all beta before the mass production to confirm the initial design and the frequency tuning procedure. This paper describes our approach for the mass production and the current status and results.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a beam from the ion source to the DTL. The beam test of the linac was started in November 2006 and 181 MeV beam was successfully accelerated in January 2007. Since then, the linac has been delivered beams for commissioning of the linac itself, downstream accelerators and facilities. Trip rates of the RFQ, however, unexpectedly increased in Autumn 2008, and we have been suffering from this issue for user run operation since then. We tried to recover by tender conditioning, modification of RF control, improvement of vacuum properties and so on. By taking these measures, we manage to have 2 to 3 days continuous beam operation. In this report, we describe the status of the RFQ.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
We have recently demonstrated 300-kW output in the J-PARC 3-GeV RCS. In this paper we will discuss beam dynamics issues in such a high intensity beam operation together with the corresponding beam simulation results.
JAEA/J-PARC, Tokai-mura
The J-PARC 3-GeV rapid cycling synchrotron (RCS) has been operated for the neutron and MLF users program from December 23rd, 2008. The RCS operations not only in support of the MLF but also were providing beam to support commissioning of the MR. In parallel we are challenging to realize higher beam power operations with better stability. Before scheduled maintenance last summer beam power was limited by the front end of about 20 kW, after that maintenance the RCS has been operated the beam power of more than 100 kW for MLF users. After beam deliver operation to the MR and MLF, while the priority has been given to their beam tuning, the RCS also continues further beam studies toward higher beam intensity. On December 7th, 2009, the RCS achieved the beam power of more than 300kW to the neutron production target with 25Hz. This presentation will concentrate itself on the outcome of the J-PARC RCS commissioning program, including the discussion on the issues of the high-power operation.
IHEP Beijing, Beijing
The accelerator of China Spallation Neutron Source (CSNS) consists of a low energy linac and a Rapid Cycling Synchrotron (RCS). The opimization of beam dynamics design for RCS and two beam transport line are introduced, and the details design and some simulation results are presented.
TUB, Beijing
LANL, Los Alamos, New Mexico
IHEP Beijing, Beijing
NUCTECH, Beijing
CIAE, Beijing
Institute of Physics, Chinese Academy of Sciences, Beijing
IMP, Lanzhou
Tsinghua University, Beijing
CERN, Geneva
This paper reports the design and construction status, technical challenges, and future perspectives of the proton-linac based Compact Pulsed Hadron Source (CPHS) at the Tsinghua University, Beijing, China.
PSI, Villigen
A new current monitor (MHC5) based on a re-entrant cavity tuned at the 2nd RF harmonic (101.26 MHz) has been in operation since April 2009 at PSI. It monitors the current of the high intensity 590 MeV proton beam at 8 m downstream of the graphite meson production target (TgE). The scattered particles and their secondaries from TgE introduce a heavy thermal load approximately of 230 W on MHC5 at 2 mA beam intensity, which is carried away by active water cooling. The inhomogeneous temperature profile in MHC5 results in thermomechanical deformations which leads to a change in its HF electromagnetic characteristics. Indeed, an anomalous RF drifts were observed during initial operations, which had to be compensated for, to obtain correct beam current monitoring. In this paper, the physics of the observed RF drift is analyzed by using advanced multiphysics simulation technologies.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. The accelerator facility consists of a 70 MeV H- linac and a 50 Hz proton synchrotron accelerating up to 3.75x1013 protons per pulse from 70 to 800 MeV, delivering a mean beam power of 0.24 MW. Present upgrade studies are investigating how replacement of the existing linac and increased injection energy could increase beam power in the existing ISIS ring. Such an upgrade would replace one of the oldest sections of the ISIS machine, and with reduced space charge and optimised injection, may allow substantially increased intensity in the ring, perhaps towards the 0.5 MW regime. A critical aspect of such an upgrade would be the new higher energy injection straight. This paper summarises beam dynamics and hardware requirements for 180MeV H- charge exchange injection into ISIS including; optimisation of the injection magnets; requirements for beam dumps and results of stripping foil simulations with estimates of stripping efficiency and foil heating.
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
A 4m-long, 324MHz four-vane RFQ, consisting of four coupled sections, is currently being designed for the Front End Test Stand (FETS) at RAL in the UK. A novel design method, integrating the CAD and electromagnetic design of the RFQ with beam dynamics simulations, is being used to optimise the design of the RFQ. Basic RFQ parameters are produced with the RFQSIM code. A full CAD model of the RFQ vane tips is produced in Autodesk Inventor, based upon these parameters. This model is then imported into a field mapping code to produce a simulation of the electrostatic field around the vane tips. This field map is then used to model the beam dynamics within the RFQ using General Particle Tracer (GPT). Previous studies have been carried out using field mapping in CST EM Studio. A more advanced technique using Comsol Multiphysics and Matlab, that more tightly integrates the CAD modelling, field mapping and beam dynamics simulations, is described. Results using this new method are presented and compared to the previous optimisation process using field maps from CST.
University of Warwick, Coventry
Fundación Tekniker, Elbr (Guipuzkoa)
Bilbao, Faculty of Science and Technology, Bilbao
Fundación TEKNIKER, Eibar (Gipuzkoa)
STFC/RAL, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL/ISIS, Chilton, Didcot, Oxon
Elytt Energy, Madrid
Imperial College of Science and Technology, Department of Physics, London
The Front End Test Stand (FETS) at the Rutherford Appleton Laboratory is intended to demonstrate the early stages of acceleration (0-3 MeV) and beam chopping required for high power proton accelerators, including proton drivers for pulsed neutron spallation sources and neutrino factories. A Low Energy Beam Transport (LEBT), consisting of three solenoids and four drift sections, is used to transport the H- beam from the ion source to the FETS Radio Frequency Quadrupole. We present the status of the installation and commissioning of the LEBT, and compare particle dynamics simulations with preliminary measurements of the H- beam transport through the LEBT.
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The Front End Test Stand (FETS) is an experiment based at the Rutherford Appleton Laboratory (RAL) in the UK. The test stand is being constructed in collaboration between STFC, Imperial College London, ASTeC, the University of Warwick and the Universidad del Pais Vasco. This experiment will design, build and test the first stages necessary to produce a very high quality, chopped H- ion beam as required for the next generation of high power proton accelerators (HPPAs). HPPAs with beam powers in the megawatt range have many possible applications including drivers for spallation neutron sources, neutrino factories, accelerator driven sub-critical systems, waste transmuters and tritium production facilities. An automatic tuning system has been developed for the main 324MHz 4-vane RFQ accelerator and has been tested to fine tune the changes in the resonant frequency of a 324MHz 4-vane cold model RFQ, which been designed as part of the development of the test stand. This paper will present the electronics design of the automated tuning system along with the mechanical tuner structure. The design concepts will be discussed. Furthermore, results of the RF tuning would be presented.
Fermilab, Batavia
The concept design of the 2.5 GeV superconducting CW linac of the Project X is discussed. The linac structure and break points for different cavity families are described. The results of the RF system optimization are presented as well as the lattice design and beam dynamics analysis.
ORNL, Oak Ridge, Tennessee
The Spallation Neutron Source accelerator complex consists of a 2.5 MeV H- front-end injector system, a 186 MeV normal-conducting linear accelerator, a 1 GeV superconducting linear accelerator, an accumulator ring, and associated beam transport lines. Since initial operation began in 2006, the beam power has been steadily increasing toward the design goal of 1.4 MW. In September 2009 the power surpassed 1 MW for the first time, and operation at the 1 MW level is now routine. The status of the beam power ramp-up program and present operational limitations will be described.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
The front end test stand (FETS) [1] being constructed at the Rutherford Appleton Laboratory is entering the next stage of commissioning, with the three-solenoid magnetic low energy beam transport (LEBT) now installed and undergoing commissioning. The next major component to be manufactured is the 3 MeV, 324 MHz, four metre radio frequency quadrupole (RFQ). The mechanical design is almost complete so a comprehensive finite element model of the entire RFQ has been made in ANSYS to ensure the electromagnetic, thermal and structural properties are sound. An analysis of the cooling strategy and expected resonant frequency shift due to thermal expansion are presented.
Fermilab, Batavia
As the Fermilab Tevatron Collider program draws to a close, a strategy has emerged of an experimental program built around the high intensity frontier. The centerpiece of this program is a superconducting H- linac that will support world leading programs in long baseline neutrino experimentation and the study of rare processes. Based on technology shared with the International Linear Collider, Project X will provide multi-MW beams at 60-120 GeV from the Main Injector, simultaneous with very high intensity beams at lower energies. Project X also supports development of a Muon Collider as a future facility at the energy frontier.
GSI, Darmstadt
The FAIR accelerator project at GSI should increase the intensity of primary proton and heavy ion beams by up to two orders of magnitude, relative to the existing GSI facility. In addition to the design of the new synchrotron SIS-100 and the storage rings, the intensity upgrade of the SIS-18 synchrotron plays a key role for the FAIR project. Recently a new record beam intensity for intermediate charge state uranium ions has been achieved in the SIS-18. Still several challenges related to beam intensity effects and phase space conservation have to be mastered in order to reach the beam parameters required for the injection into SIS-100. In SIS-100 beam loss control and machine protection are of major concern. Lost energetic heavy ions can cause a more severe damage of accelerator components than the corresponding amount of protons. Gradual beam loss of energetic ions is expected to occur in SIS-100 mainly during slow extraction of intense beams. Coherent transverse instabilities induced by the beam pipe impedance are a potential cause of fast beam loss and emittance increase. Cures and protection measures together with the result of simulation studies will be summarized.