IHEP Beijing, Beijing
China Spallation Neutron Source (CSNS) consist of an H- linac as an injector of a rapid cycling synchrotron of 1.6 GeV. The 324 MHz rf linac is designed with beam energy of 81 MeV and a peak current of 30 mA. The linac design and R&D are in progress. A test stand of a Penning ion source is under construction. RFQ technology has been developed in ADS study, with beam energy of 3.5 MeV, a peak current of 47 mA at 7% duty factor and a beam transmission rate more than 94%. The first segment of the DTL tank has been fabricated. This paper will introduce the design and R&D status of the linac.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
KEK/JAEA, Ibaraki-Ken
The J-PARC linac has been successfully commissioned up to its design energy and almost design peak intensity. The unique methods and hardware features adopted in the J-PARC linac, such as the Cs-free H- ion source, macro-pulse generation method, stable one-shot operation method, rf chopper system related with the J-PARC 30mA-RFQ (Radio Frequency Quadrupole linac) design and its operation parameter, one-turn injection method into the following J-PARC RCS (Rapid Cycling Synchrotron), transverse matching using TRACE3D PMQ (Permanent Magnet Quadrupole) elements approximating the fringe field effects of the electro-quadrupole magnets, 2 cavity behavior of SDTL (Separated Drift tube Linac) fed with one Klystron and so on, will be reported in this talk.
CERN, Geneva
In its June 2007 session the CERN Council has approved the White Paper, which includes construction of a 160 MeV H- linear accelerator called LINAC4, and the study of a 4 GeV Superconducting Proton Linac (SPL). LINAC4 will initially replace LINAC2 as the injector to the PS Booster, improving its performance up to the levels required for producing the ultimate LHC luminosity. In a later stage, LINAC4 is intended to become the front-end of SPL in a renewed injection chain for the LHC, which could be progressively constructed over the next decade. After briefly introducing the motivations and layout of the new injector chain, the talk will present the characteristics of the new linacs and give an overview of their main technical features and the R&D activities pursued within the HIPPI Joint Research Activity.
CERN, Geneva
MPQ, Garching, Munich
Linac 4 is a 160 MeV H- linac which will become the new injector for CERN's proton accelerator chain. The linac will consist of 4 different rf structures, namely RFQ, DTL, CCDTL and PIMS running at 352.2 MHz with 2 Hz repetition rate and 0.4 ms pulse length. A chopper line ensures clean injection into the PS Booster. The combination of high frequency and a high-current, low-emittance beam calls for a compact design where minimum space is left for diagnostics. On the other hand, diagnostics is needed for setting up and tuning of the machine during both commissioning and operation. A measurement strategy and the corresponding choice of the diagnostic devices and their specific use in Linac4 are discussed in this paper.
NIRS, Chiba-shi
AEC, Chiba
SHI, Tokyo
An interdigital H-mode structure drift tube linac (IH-DTL) with alternating phase focusing (APF) has been developed downstream of a 4-vane type RFQ linac at the National Institute of Radiological Sciences as a compact injector for a heavy-ion medical synchrotron. The rf frequency of both linacs is 200 MHz, and the total length of the two linacs is less than 6 m. They can accelerate heavy ions having a charge to mass ratio of 1/3 up to 4 MeV/u. The accelerated current of 12C4+ is as high as 380 electric μA, and beam transmission through the APF IH-DTL is better than 96%. This compact injector-linac scheme might give a possible solution for a compact cancer therapy facility with heavy-ion beams.
GSI, Darmstadt
The Heidelberg Ion-Beam Therapy Centre (HIT) is the first dedicated clinical synchrotron facility for cancer therapy using energetic proton and ion beams (C, He and O) in Europe. The accelerator consists of a 7 MeV/u, 217 MHz injector linac and of a 430 MeV/u synchrotron. The installation and commissioning of the linac has been performed gradually in three steps for the ion sources and the LEBT, for the 400 keV/u RFQ, and for the 20 MV IH-type drift tube linac. The initial commissioning of the linac was finished successfully in December 2006, the commissioning of the synchrotron and of the high-energy beam lines with beam was finished for two fixed-beam treatment places in December 2007. Commissioning of the heavy-ion gantry is still going on. The results of the linac commissioning will be reported as well as the experience of more than one year of linac operation. To provide optimum conditions for patient treatment, an intensity upgrade programme has been initiated for the linac. A copy of the HIT linac is presently installed at the Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia, Italy. The status of the CNAO linac will be also reported.
IAP, Frankfurt am Main
Funding: GSI, BMBF contr. No. 06F134I, EU contr. No. 516520-FI6W, RII3-CT-2003-506395, EFDA/99-507ERB500CT990061
Worldwide there is an increasing interest in new high intensity proton and ion driver linacs with beam powers up to several MW. A very challenging part of these accelerators is the low and medium energy section up to 100 MeV. Depending on the duty cycle room temperature or superconducting options are favoured. In both cases the Crossbar-H-mode (CH)-structure, developed at the IAP in Frankfurt is an excellent candidate. Room temperature as well as superconducting prototype cavities have been developed and tested successfully. A superconducting 19 cell low energy (beta=0.1) CH-cavity at 360 MHz reached effective gradients of 7 MV/m corresponding to an accelerating voltage of 5.6 MV. This cavity could be used for high intensity, cw operated linacs like accelerator driven systems (ADS, EUROTRANS) or the international fusion material irradiation facility (IFMIF). Additionally, the new proton injector for FAIR (325 MHz, 70 mA, 70 MeV) will use room temperature CH-cavities. Recent developments of this new type of a multi-cell drift tube cavity, beam dynamics issues and the tests of the prototypes will be presented.
RAS/INR, Moscow
TRIUMF, Vancouver
In this report we consider room temperature DTL structure for heavy ions acceleration in energy range 150 keV/u - 400 keV/u. The structure design is based on known and proven solutions. Due to design idea, the structure has no end wall problem. It allows flexible segmentation in cavities and transverse focusing elements placing outside cavity. As compared to well known IH DTL, considered structure has smaller transverse dimensions and is designated for lower operating frequency. The structure promises high rf efficiency - with careful elements optimization calculated effective shunt impedance value is higher than 1.0 GOhm/m for operating frequency ~ 70 MHz, E~150 keV/u.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The ISIS linac consists of four DTL tanks that accelerate a 50 pps, 20 mA H- beam up to 70 MeV before injecting it into an 800 MeV synchrotron. Over the last decades, the linac has proved to be a strong and reliable injector for ISIS, which is a significant achievement considering that two of the tanks are more than 50 years old. At the time the machine was designed, the limited computing power available and the absence of 3D electromagnetic (EM) simulation codes, made the creation of a linac optimized for power efficiency almost impossible, so from this point of view, the ISIS linac is quite simple by today's standards. In this paper, we make a shunt impedance comparison study using the power consumption data collected from ISIS and the results obtained when simulating each of the four DTL tanks with 2D and 3D EM codes. The comparison will allow us to check the accuracy of our simulation codes and models and to assess their relative performance. It is particularly important to benchmark these codes against real data, in preparation for their use in the design of a proposed new linac, which will replace the currently aging ISIS injector.
LANL, Los Alamos, New Mexico
The surface losses in the drift-tube linac (DTL) tanks 3 and 4 of the LANSCE linear accelerator are calculated using 3-D electromagnetic modeling with the CST MicroWave Studio (MWS). The results are used to provide more realistic power estimates for the 201.25 MHz rf upgrade design within the LANSCE-R project. We compared 3-D MWS results with those from traditional 2-D Superfish computations for DTL cells and their simplified models and found differences on the level of a few percent. The differences are traced to a 3-D effect consisting in a redistribution of the surface currents on the drift tubes (DT) produced by the DT stem. The dependence of MWS results on the mesh size used in computations is also discussed.
KAERI, Daejon
The requirements for the field amplitude and phase stability of the PEFP linac are 1% and 1 degree, respectively. To achieve the requirements, a digital LLRF control system has been developed using a commercial digital board for general purpose(FPGA). The feedback with PI control and feedforward are implemented in the FPGA. The LLRF control systems are currently used for the linac test. In this paper, test results and discussion on the advantage and disadvantage of the LLRF system based on a commercial board are presented.
RAS/INR, Moscow
Stabilization of amplitude and phase in linear accelerator cavities can be realized by means of control systems, operating both in polar (A/P) and rectangular (I/Q) coordinates. In analyzing of linear control systems, as a rule, transfer functions are used, which, in turn, are the symbolic representation of the linear differential equation, connecting the input and output variables. It's well known that generally in A/P coordinate it is impossible to get two separate linear differential equations for amplitude and phase of rf voltage in a cavity except for estimating of the control system stability in the small near steady state values of variables. Nevertheless, there is a possibility of numerical simulation of nonlinear A/P control system using up-to-date programs. Some results of the simulation are presented.