INFN/LNS, Catania
CSFNSM, Catania
The properties of ECRIS plasmas have been largely studied, however the design of new generation sources, able to provide high intensity beams of multiply charged ions, requires a more accurate investigation of both electron and ion dynamics. ECRIS have a broad electron energy distribution function (EEDF), not ideal for the safe operation of the sources, especially when superconducting magnets are used. X-rays measurements reveal a large amount of MeV electrons, that locally heat the cryostat and make the aging of the insulator faster. Conditions for the suppression of high energy particles must be understood in order to fully exploit the ECRIS ability to produce high brightness beams, and the plasma heating modelling permits a better insight. In addition, our approach takes into account the resonant nature of the plasma chamber, that has been confirmed by simulations and experiments: slight variations of frequency change the pattern of the electromagnetic field over the resonance surface, thus affecting the EEDF. A model has been developed to link the electron and ion dynamics, explaining how the beam properties are influenced by slight variations of the pumping frequency.
ESS Bilbao, Bilbao
Bilbao, Faculty of Science and Technology, Bilbao
ESS-Bilbao, Zamudio
The goal of extracting high proton currents from the ECR source of the Bilbao Accelerator has required comprehensive and interactive studies by using systematic beam dynamics simulations to derive acceptable geometric parameters for the projected electrode extraction system. Two tetrode designs were mainly analyzed; the first is based on a Pierce geometry; and the second on a spherically convergent extraction system. Both designs consist of a plasma electrode at 75kV, and then, a puller system formed by a grounded electrode separated from the plasma chamber to a certain extraction-gap distance, an electron repeller electrode fed at -3kV, and finally a grounded electrode. Geometric parameters such as the distances between electrodes, the different electrode apertures, the plasma electrode angle related to the Pierce layout, and also, the plasma and extraction electrode radial shapes related to the spherical extractor design were optimized for a 70mA proton beam.
CERN, Geneva
A new 450 GeV/c extraction kicker concept has been investigated for the SPS, based on open C-type kickers and a fast-bumper system. The beam is moved into the kicker gap only a few ms before extraction. The concept is illustrated in detail with the LSS4 extraction in the SPS very similar parameters and considerations apply to the other fast extraction system in LSS6. A similar concept could also be conceived for injection but is more difficult due to the larger beam size. The technical issues are presented and the potential impact on the machine impedance is discussed.
Fermilab, Batavia
MSU, East Lansing, Michigan
The current design of beam preparation for a proposed mu->e conversion experiment at Fermilab is based on slow resonant extraction of protons from the Debuncher. The Debuncher ring will have to operate with beam intensities of 2-3 x 10**{12} particles, approximately four orders of magnitude larger than its current value. The most challenging requirements on the beam quality are the spill uniformity and low losses in the presence of large space charge and momentum spread. We present results from simulations of third integer resonance extraction assisted by RF knock-out (RFKO), a technique developed for medical accelerators. Tune spreads up to 0.05 have been considered.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
We use the ORBIT particle tracking code to simulate the propagation of 545 keV electrons stripped from 1 GeV H- ions during injection into the Spallation Neutron Source accumulator ring. The electrons propagate in the field of the injection magnet and are subject to scattering at the bottom surface when they are not caught by the electron catcher in the design fashion. The scattered electrons have the potential to intercept and damage local hardware. We model the non-caught electrons and compare our simulated results with experimental observations.
Siemens AG, Healthcare Technology and Concepts, Erlangen
An RF accelerator driver concept is introduced, which integrates a distributed solid-state RF power source with the RF resonator. The resulting structure plays a double role as RF combiner and particle accelerating structure [1]. The key enabling technologies are Silicon Carbide RF transistors and a power combiner concept which includes insulating parallel cavities to ensure consistent RF current injection. An experimental direct drive λ/4 cavity with a power rating of 500kW at 150MHz has been constructed. The Direct Drive RF power source consists of 64 RF modules constructed from Silicon Carbide vJFETs, radial power combiner and isolation cavity. The initial results from the integration of the direct drive RF source are presented. These results demonstrate experimentally for the first time the validity of the direct drive concept and the key characteristics of such a drive.
[1] O. Heid, T Hughes. "Compact Solid State Direct Drive RF LINAC" presented at IPAC 2010, Kyoto, Japan.
Fermilab, Batavia
ORNL, Oak Ridge, Tennessee
BNL, Upton, Long Island, New York
One of the initial motivations for replacing the aging Fermilab Proton Source was to support the 120 GeV Neutrino program at the 2 MW level while supporting a broad 8 GeV Physics program. Over the years the design parameters of the new Proton Source have evolved from the 2005 Proton Driver configuration of a 2MW 8 GeV pulsed H- linac injecting directly into the Main Injector or Recycler ; to a 2MW 2 GeV CW linac supporting a 2 GeV Experimental Program while injecting into a new 2-8 GeV Rapid Cycling Synchrotron which would then supply protons to the Main Injector. The current design parameters of the project include a 3 GeV CW linac accelerating up to 1 mA (average) H- and a 3 GeV Experimental Area with the connection to the Main Injector Complex as an upgrade. Whether the upgrade path includes a new 6(or 8)GeV CW or pulsed linac, or 3 to 8 GeV RCS and the ultimate linac current remains to be determined. The basic issues of injection insertion design, foil and laser stripping options, foil survivability and loss issues will be discussed in context of the present options. Both analytical estimates and simulation results will be discussed.
OXFORDphysics, Oxford, Oxon
JAI, Egham, Surrey
PAMELA (Particle Accelerator for MEdicaL Application) is a design study of particle therapy facility using FFAG. PAMELA lattice realizes stable betatron tune with relatively small orbit excursion for a field accelerator with the help of newly developed combined function magnet. In addition, it can flexibly change the operating point, The feature puts PAMELA in a unique position among fixed field accelerators. The challenge of the beam extraction in PAMELA is the variability of extraction energy. Though the feature is desirable tto improve the beam quality for treatment, it was hard to realize for a fixed field accelerator due to orbit excursion introduced by the fixed field nature. The small orbit excursion of PAMELA provides a possibility to realize it. To tackle the problem, PAMELA employed vertical extraction with large gap kicker magnet, which is one of the major R&D items of the project. . In the presentation, the extraction scheme, status of hardware development and other approach of extraction PAMELA lattice will be presented.
CERN, Geneva
The LHC has two dedicated cleaning insertions: IR3 for momentum cleaning and IR7 for betatron cleaning. During the first months of beam experience the presently installed Phase-I system performed as predicted earlier in detailed studies with tracking simulations. As the current system is not sufficient to allow LHC operation with nominal or ultimate intensity at 7TeV/c, simulations with an upgraded system are ongoing to overcome these limitations. In this contribution a collimation scheme with combined momentum and betatron cleaning in IR3 with additional collimators in the IR3 dispersion suppressor is presented. The predicted improvements compared to the Phase-I system and the limitations of this scheme are discussed.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
The Japan Proton Accelerator Research Complex (J-PARC) consists of a 400 MeV linac (181 MeV at present), a 3 GeV rapid cycling synchrotron (RCS), a 50 GeV (30 GeV at present) main ring (MR) and several experimental facilities. At present the entire accelerator complex is in the operational stage and delivering relatively a high power beam to all experimental facilities. There are two stages of injection and extraction in the entire complex. The RCS utilizes charge-exchange H- painting injection scheme, then accelerate beam up to 3 GeV and is simultaneously extracted for the Material and Life science Facility (MLF) and for the MR injection. Starting with a 3GeV injection, the MR accelerates beam up to 30 GeV and delivered either to the neutrino experimental facility or to the hadron experimental facility through corresponding extraction channel. In order to have a high quality beam, there are many challenges in each accelerator especially, with injection and extraction systems and becomes significant towards achieving higher beam power. The operational experience from all aspect with J-PARC injection and extraction systems will be presented.
CERN, Geneva
Linac4 will replace the currently used Linac2 in the LHC injector chain. The motivation is to increase the proton flux available for the CERN accelerator complex and eventually achieve the LHC ultimate luminosity goals. Linac4 will inject 160MeV H- ions into the four existing rings of the PS Booster (PSB). A new charge-exchange multi turn injection scheme will be put into operation and require a substantial upgrade of the injection regions. Four kicker magnets (KSW) will be used to accomplish transverse phase space painting in order to match the injected beams to the required emittances. This paper presents hardware issues and related beam dynamics studies for several painting schemes. Results of optimization studies of the injection process for different beam characteristics and scenarios are discussed.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
LANL, Los Alamos, New Mexico
BNL, Upton, Long Island, New York
The Spallation Neutron Source comprises a 1 GeV, 1.4 MW linear accelerator followed by an accumulator ring and a liquid mercury target. To manage the beam loss caused by the H0 excited states created during the H− charge exchange injection into the accumulator ring, the stripper foil is located inside one of the chicane dipoles. This has some interesting consequences that were not fully appreciated until the beam power reached about 840 kW. One consequence was sudden failure of the stripper foil system due to convoy electrons stripped from the incoming H− beam, which circled around to strike the foil bracket and cause bracket failure. Another consequence is that convoy electrons can reflect back up from the electron catcher and contribute to foil and bracket failure. An additional contributor to foil system failure is vacuum breakdown due to the charge developed on the foil by secondary electron emission. In this paper we will detail these and other interesting failure mechanisms, and describe the improvements we have made to mitigate them.
ORNL RAD, Oak Ridge, Tennessee
Advancements in laser technology have dramatically expanded the applications of lasers to particle accelerators. Today, lasers have been used for accelerators in a broad range from operational systems such as nonintrusive particle beam diagnostics instruments and photoinjectors, to elaborate applications with high technical readiness levels including, for instance, a laser assisted foil-less charge exchange injection scheme and laser-electron Compton scattering-based light sources, and finally to exotic topics such as laser driven electron/ion accelerators. This talk reviews recent experimental results achieved in the above applications, their requirements on laser parameters and challenges that require future laser technology development. Important technical elements including femto-second pulse generation, burst-mode optical amplifiers, beam stacking from laser arrays, and power enhancement optical cavity will be briefly described. The laser optics development for the laser wire beam profile monitors and the laser stripping experiment at SNS will also be introduced as application examples.
CERN, Geneva
The increase of the extraction energy of the CERN PSB to 2 GeV has been suggested as a method to increase the intensity of the LHC beam which can be obtained from the present injector complex. Such a change would require a redesign of the present PS proton injection system, which is already operating close to its limits within tight space constraints. The feasibility of a 2 GeV proton injection is discussed and a potential solution outlined. The implications on the injection equipment and on the performance in terms of beam parameters and losses are discussed.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG to be hosted at Daresbury Laboratory. NS-FFAGs related to EMMA have an unprecedented potential for medical accelerators for carbon and proton hadron therapy. It also represents a possible active element for an ADSR (Accelerator Driven Sub-critical Reactor). This paper will summarize the design of the extraction and injection transfer lines of the NS-FFAG as well as the septa and kickers used to inject into the EMMA ring. In order to operate EMMA, the ALICE energy recovery linac prototype shall be used as injector and the energy will range from 10 to 20 MeV. Because this would be the first non-scaling FFAG, it is important that as many of the bunch properties are studied as feasible, both at injection and at extraction. To do this, a complex injection line was designed consisting of a dogleg to extract the beam from ALICE, a matching section, a tomography section and some additional dipoles and quadrupoles to transport the beam to the entrance of EMMA. In parallel with injection, extraction and a dedicated extraction / diagnostic line is also discussed.
KAERI, Daejon
BNL, Upton, Long Island, New York
The 100-MeV proton linac of the proton engineering frontier project (PEFP) can be used as an injector of a rapid cycling synchrotron (RCS). The design study of the RCS is in process. The main purpose of the RCS is a spallation neutron source. The initial beam power is 60 kW where the injection and extraction energies are 100 MeV and 1 GeV, respectively. It will be extended to 500 kW through the upgrades of the injection energy to 200 MeV, the extraction energy to 2-GeV, and the repetition rate from 15 Hz to 30 Hz. The slow extraction option is also included in the design for basic and applied science researches. This work summarized the present design status of the PEFP RCS.
BNL, Upton, Long Island, New York
Examples of new possible applications of the racetrack non-scaling FFAG (NS-FFAG) will be shown with detail designs: A small permanent proton cancer therapy machine, the ADSR with superconducting cavities, the proton or pion storage rings made of the non-scaling FFAG with large momentum acceptance (dp/p=± 30%) for longitudinal manipulations, a new design of the PRISM with NS-FFAG for the muon acceptance storage ring (collaboration with UK), and RLA with racetrack or dog-bone recent examples (collaboration with Alex Bogacz at IPAC).