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.
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/
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.
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.
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.
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
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.
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.
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.
KEK, Ibaraki
KEK injector linac provides an injection beam for four storage rings, KEKB high energy electron ring(HER), low energy positron ring(LER), PF-AR electron ring, and PF electron ring. The injection beams for these rings have different energies and intensities. Recently, a requirement of simultaneous injection among these rings arises to make a top-up injection possible. Magnetic fields of DC magnets to confine the beam to the accelerating structures can not be changed between pulse to pulse, although the beam energy can be controlled by fast rf phase shifters of klystrons. This implies that a common magnetic field of the bending magnets and the quadrupole magnets should be utilized to deliver beams having different characteristics. Therefore, we have designed multi-energy optics for the KEKB-HER electron ring(8 GeV, 1 nC/pulse), the PF electron ring(2.5 GeV, 0.1 nC/pulse), and the KEKB-LER positron ring(3.5 GeV, 0.4 nC/pulse). We present a performance of the multi-energy injector linac.
CERN, Geneva
An automatic beam steering application for CTF 3 is being designed in order to automatize operation of the machine, as well as providing a test-bed for advanced steering algorithms for CLIC. Beam-based correction including dispersion free steering have been investigated. An approach based on a PLACET on-line model has been tested. This paper gives an overview of the current status and the achieved results of the CTF3 automatic steering.
CERN, Geneva
The CERN CLIC test facility (CTF3) aims at assessing the feasibility of the future multi-TeV Compact Linear Collider (CLIC). The CTF3 Tail Clipper Collimator (TCC) will serve to adjust the bunch train length of the beam extracted from the combiner ring, in combination with a fast kicker magnet. In addition, the TCC will operate, when required, as an internal beam dump. The challenge of the TCC design is to meet the requirements of both collimator and dump operational modes for a low energy e- beam (100-300 MeV) of 35 A peak intensity. The TCC collimator will be installed at the end of 2008 in the TL2 transfer line of CTF3. This paper describes the final design of the TCC and the main issues related to its integration in the line.
SAIC, Los Alamos, New Mexico
LANL, Los Alamos, New Mexico
LLNL, Livermore, California
NSTec, Los Alamos, New Mexico
Voss Scientific, Albuquerque, New Mexico
The DARHT-II accelerator produced a 2 kA, 17 MeV beam over a 1600 ns flattop. After exiting the accelerator, the long pulse is sliced into four short pulses by a kicker and quadrupole septum and then transported and focused on a target for conversion to bremsstrahlung for radiography. We describe the initial commissioning tests of the kicker, septum, transport, and multi-pulse converter target. The results of beam measurements made during the commissioning of the accelerator downstream transport are described. Beam optics simulations of the commissioning results are described.
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.
An energy recovery linac (ERL) is one of the candidates for an upgrade of the Advanced Photon Source (APS). In addition to the APS ring and full-energy linac, our design also includes a large turn-around arc that could accommodate new X-ray beamlines as well. In total, the beam trajectory length would be close to 3 km. The ERL lattice has a strong focusing to limit emittance growth, and it includes strong sextupoles to keep beam energy spread under control and minimize beam losses. As in storage rings, trajectory errors in sextupoles will result in lattice perturbations that would affect delivered X-ray beam properties. In storage rings, the response matrix fit method is widely used to measure and correct linear lattice errors. Here, we explore the application of the method to the linear lattice correction of ERL.
SLAC, Menlo Park, California
The beam stability for the Linac Coherent Light Source (LCLS) Free-Electron Laser (FEL) at Stanford Linear Accelerator Center (SLAC) are critical for X-Ray power, pointing, and timing stability. Studies of the transverse, longitudinal, and intensity stability of the electron beam are presented. Identifying these sources by different methods like correlations, frequency spectrum analysis and other methods is critical for finally eliminating or reducing them.
Kyoto ICR, Uji, Kyoto
KEK, Ibaraki
A final focus quadrupole (FFQ) doublet of ILC should have excellent properties such as strong focusing, compactness and less vibrations. In a baseline design, superconducting magnet is supposed to be used, which may have some vibrations traveling through liquid helium. It may not be suitable for FFQ of ILC unless the vibration effect is proven to be negligible. Since the five-disc-singlet proposed by Gluckstern satisfies these properties including continuous adjustability, we are developing a FFQ aiming at a beam test at ATF2. Although the x-y coupling effect is carefully cancelled in the design, fabrication errors or rotation errors may break the cancellation. We are estimating the effect of these errors on the beam size at the interaction point. Two methods are currently carried out. The first one is transfer matrix calculations, which neglects fringing field and higher multipole components. The second one is beam-tracking calculation in measured or calculated magnetic field. The fabricated magnet is under adjustment measuring the magnetic field. The recent results will be presented.
CERN, Geneva
INFN/LNF, Frascati (Roma)
TRIUMF, Vancouver
The objective of the CLIC Test Facility CTF3 is to demonstrate the feasibility issues of the CLIC two-beam technology. CTF3 consists of an electron linac followed by a delay loop, a combiner ring and a two-beam test area. One issue studied in CTF3 is the efficient generation of a very high current drive beam, used in CLIC as the power source to accelerate the main beam to multi-TeV energies. The beam current is first doubled in the delay loop and then multiplied by a factor four in the combiner ring by interleaving bunches using transverse deflecting rf cavities. The combiner ring and the connecting transfer line have been put into operation in 2007. In this paper we give the status of the commissioning, present the results of the combination tests and illustrate in some detail the beam optics measurements, including response matrix analysis, dispersion measurement and applied orbit correction algorithms. We discuss as well the observation of a vertical beam break-up instability which is due to the vertical transverse mode in the horizontal rf deflectors used for beam injection and combination. We outline the attempted methods to mitigate the instability and their effectiveness.
LANL, Los Alamos, New Mexico
We are developing high-efficiency room-temperature rf accelerating structures for beam velocities in the range of a few percent of the speed of light by merging two well-known ideas: H-mode cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we have found that the H-mode structures with PMQ focusing provide a very efficient and practical accelerator for light-ion beams of considerable currents. Such accelerating structures following a short RFQ can be used in the front end of ion linacs or in stand-alone applications such as a compact deuteron-beam accelerator up to the energy of a few MeV.
ANL, Argonne
Funding: Work at Argonne was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No DE-AC02-06CH11357.
The LCLS, now under construction at the Stanford Linear Accelerator Center (SLAC) in California, will be the world's first X-ray free-electron laser when it comes online next year. Design and production of the undulator system is the responsibility of a team from the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Forty 3.4-m-long high-precision undulators, 37 laminated quadrupole magnets, plus 38 support and motion systems with micron-level adjustability and stability were constructed and delivered to SLAC, where final tuning, fiducialization, and installation are underway. An overview of the undulators and support systems, including achieved results, is presented.