BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A steering magnet is not a major component in a beam line, however it is usually needed in any real set up. Also it is hard to estimate the required field strength before the beam line construction, since the strength needed is determined by misalignnment errors of other devises. Sometimes it is difficult to find enough space to install steering magnets because of other constraints on the length of the beamline. We compare two extreme designs of steering magnets. The first one is very thin steering magnet design which occupies only 6 mm in length and can be additionally installed as needed. The other is realized by applying extra coil windings to a quadrupole magnet and does not consume any length. We will present both designs in details and will discuss pros and cons.
GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
IAP, Frankfurt am Main
CEA, Gif-sur-Yvette
Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 ‘‘Structuring the European Research Area’’ program (CARE, Contract No. RII3-CT-2003-506395).
Beam dynamics experiments with high intensity beams have been conducted at the GSI UNILAC in 2006-2008 with the goal of benchmarking four major simulation codes, i.e. DYNAMION, PARMILA, TraceWin/PARTRAN and LORASR with respect to transverse emittance growth along a DTL. The experiments comprised measurements of transverse phase space distributions in front of as well as behind the DTL. Additional longitudinal bunch length measurements at the DTL entrance allowed for estimate and control of mismatch in all three planes. Measured effects of mismatch and of theoretically predicted space charge resonances (equipartitioning and others) are compared with simulations for a wide range of transverse phase advance along the DTL. This contribution is the first report on the successful measurement of a space charge driven fourth order resonance in a linear accelerator.
IHEP Beijing, Beijing
In the conventional 324 MHz DTL designed for China Spallation Neutron Source (CSNS) accelerating H- ion from 3MeV to 132MeV, there are 7 tanks and currently the R&D of tank-1 is under proceeding, which has 29 cells and 29 quadrupoles. In design, the Tank-1 has a tilt field distributed partially in order to obtain most effective energy gain and low Kilpatric parameter. In order to decrease the difficulty of tuning the partial tilt field distribution, a new analysis named transfer matrix method is introduced. Verifying of the calculation and simulation of the transfer matrix has been finished with MDTFISH code, picking parameters from CSNS and SNS. Checking the method on the model tank in CSNS will be operated.
Far-Tech, Inc., San Diego, California
The fixed-field alternate gradient (FFAG) synchrotron offers an attractive solution for systems that require rapid acceleration over a wide range of energies. The ability to rapidly tune the frequency of the accelerating cavity in the “non-scaling” variety of an FFAG synchrotron represents a fundamental barrier to their implementation in a wide variety of applications for proton, ion and muon acceleration. Initial results of the rapidly tunable cavity design for specific application to proton and light ion medical FFAG accelerators are presented.
IAP, Frankfurt am Main
A short RFQ prototype was built for tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. Simulations with CST Microwave Studio and first measurements were done. First results and the status of the project will be presented.
LANL, Los Alamos, New Mexico
The LANSCE linac RF system consists of four 201.25 MHz RF stations that supply RF power to the drift tube linac(DTL), and forty-four 805 MHz RF stations, that supply RF power to the coupled-cavity linac(CCL). There are four large high voltage power supplies for the DTL RF systems. Seven high voltage power supplies provide the power for the 805 MHz klystrons. All power supplies consist of a transformer/rectifier, Inductrol Voltage Regulator (IVR) and a capacitor bank with crowbar protection. After 39 years of operation, some components are approaching the end of life and will be refurbished through the LANSCE-R project to ensure the reliability of the machine until 2025. An analysis of the oil in the high voltage power supply units was done to assess their health to determine if units need to be replaced or repaired as part of LANSCE-R. Since 1998 the oil in each unit has been sampled and tested annually, and reprocessed when required. Gas-in-oil data for these units from 1998 to present was analyzed. The levels of each gas component, trends in the data and the significance of the each dissolved gas are discussed. The health of the units is assessed.
IHEP Beijing, Beijing
The 1.6GeV proton synchrotron proposed in the CSNS Project is a 25Hz rapid-cycling synchrotron (RCS) with 80MeV Linac. Beam power is aimed to 100kW at 1.6GeV. In this paper the designs of the prototype of DTL-Q power supply and the prototype of the resonant network with one mesh exciting in series will be introduced.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
JAEA, Ibaraki-ken
In the J-PARC Linac LLRF, for the cavity warming-up, the cavity resonance is automatically tuned to be the accelerating frequency (324MHz and 972MHz) with a mechanical tuner installed on the cavity. Now we are planning to introduce a new method of the cavity-input frequency matching into the digital LLRF control system instead of the cavity resonance tuning for the cavity worming-up. For the frequency matching with the detuned cavity, the RF frequency is modulated by way of phase rotation with the I/Q modulator, while the source oscillator frequency is still fixed. The phase rotation is automatically controlled by the FPGA. The detuned frequency of the cavity is obtained from phase gradient of the cavity field decay at the RF-pulse end. No hardware modification is necessary for this frequency modulation method. The cost reduction or the high durability for the mechanical tuner is expected in the future. The results of the frequency modulation test will be reported in this presentation.
PAL, Pohang, Kyungbuk
KAERI, Daejon
Funding: Work supported by PEFP and MEST in Korea
The objectives of the cooling system of Proton Engineering Frontier Project (PEFP) Drift Tube Linac (DTL) operated in combination with the low-level RF system (LLRF) are to regulate the resonant frequency of the drift tube cavities of 350 MHz. To provide an effective means of bringing the PEFP DTL up for a resonance condition within ±5 kHz, the prototype of the cooling system has been designed and fabricated to investigate the performance features for the servo stabilization of the cavity resonant frequency. As a result, it is estimated that the resonant frequency could be regulated less than ±1 kHz with this proposed feedback temperature controlled cooling system although introducing a little nonlinear features as the reference operating temperature changes. This report describes the design and performance test results of a cooling system, including the size of water pumping skid components and the temperature control scheme.
GSI, Darmstadt
IHEP Beijing, Beijing
In the conventional design of rf linacs, the space-charges are not in three-dimension thermal equilibrium. The space-charge couples the longitudinal and transverse will cause equipartitioning process which causes the emittance growth and the halo formation. In the design of the Chinese Spallation Neutron Source (CSNS) linac], three cases are investigated using the Hofmann stability charts to analysis and optimize the layout. In this paper, we present the equipartitioning beam study of the CSNS Alvarez DTL linac.
IAP, Frankfurt am Main
Funding: * Work supported by BMBF contr. No. 06F134I & EU contr. No. EFDA/99-507ERB5005CT990061
The International Fusion Materials Irradiation Facility (IFMIF) is looking for an efficient drift-tube linac (DTL) which can accelerate a 125mA, CW deuteron beam from 5MeV to 40MeV with a high beam quality and nearly no beam loss. Taking advantages of the KONUS dynamics concept and the H-type structure, a compact DTL design has been realized by IAP, Frankfurt University, with satisfying performances. Including simulated errors, the feasibility of the IAP scheme has been carefully checked as well.
G.H. Gillespie Associates, Inc., Del Mar, California
A PARMILA 2 Module has been developed for the Particle Beam Optics Laboratory (PBO Lab). PARMILA 2 is a FORTRAN program used to both design and simulate radiofrequency ion linear accelerators. The program can be used to design radiofrequency accelerators that include drift tube linac (DTL) structures, coupled cavity linac (CCL) structures, coupled-cavity drift tube linac (CC-DTL) structures, and superconducting accelerator structures. PARMILA 2 can also be used to simulate beams in these structures and in transport lines that with magnetic, radiofrequency and electrostatic beam optics elements. PBO Lab provides a sophisticated graphic user interface (GUI) for multiple optics codes. From the same familiar interface users can run TRANSPORT, TURTLE, MARYLIE, TRACE 3-D and DECAY-TURTLE. PARMILA 2 now joins this suite of optics codes available as PBO Lab Modules. New PBO Lab tools have been developed to assist users in utilizing different optics codes to simulate and validate the performance of an accelerator designed with PARMILA 2. An overview of the new PARMILA 2 module and associated new tools is presented and some of the GUI features are illustrated.
JAEA/J-PARC, Tokai-mura
KEK, Ibaraki
JAEA/LINAC, Ibaraki-ken
JAEA, Ibaraki-ken
Over hundred beam loss monitors (BLM) in the J-PARC LINAC have been used to measure the beam loss observed during the accelerator operation. Dose rates distributed in LINAC area were compared with beam loss records taken by the BLMs. This paper describes the results of the operational data and their comparisons with the dose rates of LINAC area.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
Wire Scanner Monitors (WSMs) and Bunch Shape Monitors (BSMs) are going to be installed in the entrance part of ACS (Annular Coupled Structure) section at the energy upgraded J-PARC linac. WSMs are used to measure transverse beam profiles, and BSMs are used to measure longitudinal beam profiles. Both are used to match beams from upstream SDTL (Separated-type Drift Tube Linac) accelerator cavities to ACS. Only a BSM will be installed in the beggining and the best location for the BSM has been chosen through studies of the tuning schemes.
CERN, Geneva
The civil engineering works of the Linac4 linear accelerator at CERN started in October 2008 and regular machine operation is foreseen for 2013. Linac4 will accelerate H- ions to an energy of 160 MeV for injection into the PS Booster (PSB). It will thus replace the ageing Linac2, which presently injects at 50 MeV into the PSB, and it will also represents the first step in the injector upgrade for the LHC aiming at increasing its luminosity. This paper reports on the status of the design and construction of the main machine elements, which will be installed in the linac tunnel from the beginning of 2012 onwards, on the progress of the civil engineering and on the ongoing activities at the Linac4 test stand.
CERN, Geneva
A one meter long hot prototype of the LINAC4 DTL, built in a collaboration with INFN Legnaro, was delivered to CERN in 2008. It was then copper plated at CERN is and is presently prepared for high-power testing at the CERN test stand in SM18. In this paper we present 2D/3D simulations and the first RF low-power measurements to verify the electromagnetic properties of the cavity and to tune it before the high-power RF tests. In particular, the influence of the post couplers was studied in order to guarantee stabilization of the accelerating field during operation. We present an equivalent circuit model of the DTL, together with a comparison of 3D simulations and measurement results for the hot model.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The present FNAL Linac H- injector has been operational since 1978 and consists of a magnetron H- source and a 750-keV Cockcroft-Walton Accelerator. The proposed upgrade to this injector is to replace the present magnetron source having a rectangular aperture with a circular aperture, and to replace the Cockcroft-Walton with a 200-MHz RFQ. Operational experience at other laboratories has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.
KAERI, Daejon
Funding: This work is supported by MEST of the Korean Government
A 100 MeV DTL as a main accelerating section of the PEFP proton linac is under development. The PEFP proton linac consists of a 50 keV proton injector based on a duoplasmatron ion source, 3 MeV four-vane RFQ, 20 MeV DTL and 100 MeV DTL. The 100 MeV DTL is composed of 7 tanks and each tank is an assembly of 3 sections. The tank is made of seamless carbon steel and inside surface is electroplated with copper. Each drift tube contains an electroquadrupole magnet which is made of hollow conductor and iron yoke with epoxy molding. Following the fabrication of tanks and drift tubes, a precise alignment of drift tubes and field flatness tuning procedure are performed. Currently four DTL tanks out of seven are completed and the rest are under fabrication. The status of development and test results of the fabricated parts are reported in this paper.
LANL, Los Alamos, New Mexico
Funding: This work is supported by the U. S. Department of Energy, Contract DE-AC52-06NA25396.
The Los Alamos Neutron Science Center simultaneously provides both H- and H+ beams to several user facilities. Opposite polarity beams are usually accelerated in the linac during the same macropulse when beam-loading limitations are not exceeded. Presently, the Weapons Neutron Research (WNR) H- and Isotope Production Facility (IPF) H+ beams are accelerated simultaneously during the same macropulse. The amplitude of the cavity field in the last 201-MHz buncher, located in the common transport just upstream of the DTL, is a compromise between the optimal values for each beam. Recent beam dynamics studies have shown that implementing a debuncher cavity in the H- low-energy beam transport would allow for more optimal operation of both beams. For this application where space is limited, a compact 201-MHz quarter-wave cavity will be used. This paper will report on the beam dynamics simulations performed and the quarter-wave cavity design being developed to address this issue.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Future projects like a neutrino factory or an advanced spallation neutron source require high power proton accelerators capable of producing beams in the multi-MW range. The quality of the beam delivered to the target is very much dictated by the accelerator front end and by the lower energy linac. Prompted by the Front End Test Stand (FETS) under construction at Rutherford Appleton Laboratory (RAL), a new 800 MeV H- linac is being considered as part of a possible MW upgrade for ISIS. Preliminary simulations of high intensity beam dynamics and beam transport in the new linac suggest that a re-evaluation of the front end Medium Energy Beam Transport (MEBT) line is necessary. In this paper different optical designs for the 3 MeV MEBT line are presented and their impact on the subsequent Drift Tube Linac (DTL) section is being analysed.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Features of a linac and ring for potential ISIS upgrades are outlined. Maximum parameters are 0.8 GeV, 0.5 MW for the H(-)linac and 3.2 GeV, 2 MW for the ring, both at 30 or 50 Hz. The linac is based on a 324 MHz frequency at low energies, having an ion source, LEBT, 3 MeV RFQ and MEBT, with A 74.8 MeV drift tube linac (DTL) and intermediate energy beam transport (IEBT). The MEBT chopper stage uses solenoid and triplet focusing, and both MEBT and IEBT have long sections for beam collimation. There are three options for the higher energies, a 648 MHz superconducting linac(ScL1, ScL2 and ScL3), a 648 MHz (CCL, ScL2 and ScL3), and a 324 MHz (ScLa) with a two-stage 972 MHz (ScLb and ScLc). The ScL1, CCL and ScLa are designed to accelerate the H(-) beam from 74.8 to ~200 MeV. The proton synchrotron design is based on a five superperiod lattice of doublet and triplet cells, and has a circumference of ~ 370 m.