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
RFQs are the new standard injector for a number of projects. The development of the 4-Rod RFQ structure has led to a number of interesting developments, which will be discussed with actual projects as examples. Recent work on the FAIR - p linac, the GSI - high charge state injector upgrade, the GSI - HITRAP, the new BNL - EBIS-RFQ, and the RFQ of the MSU - CW Reaccelerator will be presented and the status of these projects and will be discussed.
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.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
Fundación Tekniker, Elbr (Guipuzkoa)
University of Warwick, Coventry
Bilbao, Faculty of Science and Technology, Bilbao
Fundación TEKNIKER, Eibar (Gipuzkoa)
STFC/RAL, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Elytt Energy, Madrid
High power proton accelerators (HPPAs) with beam powers in the several megawatt range have many applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. The UK's commitment to the development of the next generation of HPPAs is demonstrated by a test stand being constructed in collaboration between RAL, Imperial College London, the University of Warwick and the Universidad del Pais Vasco, Bilbao. The aim of the RAL Front End Test Stand is to demonstrate that chopped low energy beams of high quality can be produced and is intended to allow generic experiments exploring a variety of operational conditions. This paper describes the current status of the RAL Front End Test Stand.
DAE/VECC, Calcutta
An ISOL type Rare Isotope Beam (RIB) Facility is being developed at VECC, Kolkata around the existing K=130 room temperature cyclotron. The possibility of using the photo-fission production route using a 50 MeV electron linac is also being explored. The production target and a 6.4 GHz ECR based charge-breeder system will lead to two beam lines. The first one, a low energy beam transport (LEBT) line consisting of a 1.7 m long, 33.7 MHz RFQ, will be dedicated to material science & other ion-beam based experiments. The second, post-acceleration beam line will accelerate the beams to 1.3 MeV/u using a longer, 3.4 m RFQ and a series of IH linear accelerators. In the first stage, the beam energy will be about 400 keV/u using three modules of linacs. Subsequently the energy will be boosted to about 1.3 MeV/u. Some of the systems have already been installed and made operational. The LEBT line has been tested and stable ion beams accelerated to 29 keV/u with high efficiency in the 1.7 m RFQ. The 3.4 m RFQ and the first IH Linac tank are under installation in the post-acceleration beam line. In this contribution an overview of the present status of the facility will be presented.
RIKEN Nishina Center, Wako, Saitama
Present status of the RIKEN heavy-ion linac (RILAC) will be reported, which has been used for the injector to the RIKEN RI-beam factory since 2006 as well as for the nuclear physics experiments on superheavy elements since 2002. An alternative injector to the RI-beam factory, consisting of a superconducting ECR ion source, an RFQ, and three DTLs, will be also discussed. The construction of the ion source will be completed in this year and the extraction test of the beams will be started from 2009. An RFQ linac, originally developed for the ion implantation*, was given to RIKEN through the courtesy of Kyoto University. Reconditioning of this RFQ is underway, which will be modified for the new injector in the near future.
*H. Fujisawa: Nucl. Instrum. Methods A345, 23 (1994).
JINR, Dubna, Moscow Region
IHEP Protvino, Protvino, Moscow Region
Goal of the NICA/MPD project under realization at JINR is to start in the coming 5-7 years an experimental study of hot and dense strongly interacting QCD matter and search for possible manifestation of signs of the mixed phase and critical endpoint in heavy ion collisions. The Nuclotron-based Ion Collider fAcility (NICA) and the Multi Purpose Detector (MPD) are proposed for these purposes. The NICA collider is aimed to provide experiment with heavy ions like Au, Pb or U at energy up to 3.5 x 3.5 GeV/u with average luminosity of 1027 cm-2s-1. The existing Nuclotron injection complex consists of HV fore-injector and Alvarez-type linac LU-20. The LU-20 accelerates the protons up to the energy of 20 MeV and ions at Z/A=0.33 up to the energy of 5 MeV/u. New injector designed for efficient operation of the NICA facility is based on Electron String Ion Source providing short (< 10 ns) and intensive (up to 10 mA) pulses of U32+ ions, one section of RFQ and four sections of RFQ Drift Tube Linac accelerating the ions at Z/A=0.12 up to 6 MeV/u of the kinetic energy. General parameters of the injector are discussed.
Linac Systems, LLC, Albuquerque, New Mexico
A 2.5 MeV, 20 mA, cw, proton linac for the Boron Neutron Capture Therapy medical application is under construction at Linac Systems. The system consists of a 25 keV microwave ion source, a solenoid lens based low energy beam transport system, a 0.75 MeV RFQ linac, a 2.5 MeV RFI linac, and the necessary service systems. Because of the superb low energy capabilities of the RFI structure, the RFQ linac need only go to 0.75 MeV, resulting in a cavity dissipation of 74 kW for the RFQ section. Because of the high rf efficiency of the RFI structure, the cavity dissipation is only 35 kW for the RFI section. Extensive thermal studies have been made to accommodate these cw heat load. The beam power is 50 kW. The rf power system is designed for an average power output of 200 kW. The RFQ and RFI sections are coupled into a single resonant unit by a quarter-wave-stub resonant coupler. The combination is driven at a single point in the RFQ structure. The total length of the linac is 2.6 meters. The system is scheduled for completion by early fall (2008).
Imperial College of Science and Technology, Department of Physics, London
University of Warwick, Coventry
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
In order to contribute to the development of high power proton accelerators in the MW range, to prepare the way for an ISIS upgrade and to contribute to the UK design effort on neutrino factories, a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. The results of numerical simulations of the particle dynamics from the charge separation dipole behind the ion source to the end of the MEBT will be presented. Previous measurements showed that the emittance of the beam delivered by the ion source exceeded our expectations by more than a factor of 3. Since then various changes in the beam extraction/post accelerator region reduced the beam emittance by a factor of 2. Simulations of the particle dynamics in the FETS based on distributions gained from recent measurements of the transversal beam emittance behind the ion source will be presented and the results for different input distributions discussed.
LANL, Los Alamos, New Mexico
Funding: This work has benefited from the use of the LANSCE at LANL. This facility is funded by the US DOE and operated by LANS for NSSA under Contract DE-AC52-06NA25396. LA-UR-08-03585.
Tuning particle accelerators is time consuming and expensive, with a number of inherently non-linear interactions between system components. Conventional control methods have not been successful in this domain, and the result is constant and expensive monitoring of the systems by human operators. This is particularly true for the start-up and conditioning phase after a maintenance period or an unexpected fault. In turn, this often requires a step by step restart of the accelerator. Surprisingly few attempts have been made to apply intelligent accelerator control techniques to help with beam tuning, fault detection, and fault recovery problems. The reason for that might be that accelerator facilities are rare and difficult to understand systems that require detailed expert knowledge about the underlying physics as well as months if not years of experience to understand the relationship between individual components, particularly if they are geographically disjoint. This paper will give an overview about the research effort in the accelerator community that has been dedicated to the use of artificial intelligence methods for accelerator beam line tuning.
IAP, Frankfurt am Main
Based on the 'tunnel' emittance used for electron focusing, a similar procedure with two pairs of slits with variable widths is proposed to evaluate fractional emittances and brilliances for ion beams. The measurement starts with closing both slits (one after the other), until a certain fraction of the beam current is cut out. The emittance and brilliance then is well defined for the passing beam part. Formulae are given for the emittance as well as for the brilliance in dependence of the slit width and current. This emittance measurement is free from the background subtraction problem found in the classical density measurement of phase space(s). The functions for the decrease of the emittance and for the increase of the brilliance in dependence of the transmitted beam current provide a figure of merit for the quality of the investigated beam. The device at the same time is also an adjustable emittance filter for the passing beam. At the expense of current the emittance and/or brilliance of a beam can be tailored to any value, which is available by the beam quality.
ANL, Argonne
Northern Illinois University, DeKalb, Illinois
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
We have developed a pepper pot - scintillator screen system to measure the emittance of low-energy dc beams extracted from an ECR ion source and post-accelerated to an energy of 75 - 90 keV/charge. Different scintillators have been tested and CsI (Tl) was chosen due to its high sensitivity, wide dynamic range and long life-time. The linearity of both the scintillator and the CCD camera has been studied. A LabVIEW code has been developed and used for on-line emittance measurements. Un-normalized rms emittances measured for 209Bi20+ and 209Bi21+ beams with current of 1.0 - 1.5 pnA are usually ~30 π mm.mrad. A complicated structure of multiple images of individual holes has been observed. The innovative combination of a special type of scintillator, a CCD camera and a fast shutter allowed us to create a very efficient emittance meter for low-energy dc ion beams. Using on-line emittance measurements, it was possible to improve the beam quality by re-tuning the ion source conditions. Because of the two-dimensional array of holes in the pepper-pot, this emittance meter can be used to observe and study four-dimensional emittance correlations in beams from ECR ion sources.
GSI, Darmstadt
Experimental results from ion beams, extracted from an Electron Cyclotron Resonance ion source (ECRIS) are presented and compared with different models used for simulation. The model for the simulation has to satisfy different facts: The energy of ions within the plasma is in the eV-range. Electrons have a different energy distribution: there are hot electrons (up to MeV range), but also low energy electrons, responsible for charge neutrality within the plasma. Because the gyration radius of ions is within the mm-range and below, ions can be extracted only if they are located on a magnetic field line which goes through the extraction aperture. Because of the gradient dBz/dz of the mirror field only these ions can be extracted, which have enough energy in direction of the field line. These conditions are fulfilled for ions which are going to be lost through the loss cone created by the hexapole. The extracted beam shows a typical behavior for an ECRIS: when the beam is focused by a lens (here a solenoid) directly behind extraction, the initial round and hollow beam develops wings with a 120-degree symmetry. These wings has influence on the beam emittance.
Kyoto ICR, Uji, Kyoto
We aim to develop a small and high intensity proton source for a compact accelerator based neutron source. Because this proton source shall be located close to RFQ for simplification, ratio of H+ to molecular ions such as H2+ or H3+ must be large. Therefore we select ECR ion source with permanent magnet as a small and high intensity ion source. ECR ion sources can provide high H+ ratio because of their high plasma temperature. Using permanent magnets makes the ion source small and running cost low. Because there is no hot cathode, longer MTBF is expected. Usually, gas is fed into ion sources continuously, even if ion sources run in pulse operation mode. But, continuous gas flow doesn't make vacuum in good level. So, we decided to install pulse gas valve directly to the plasma chamber. Feeding the gas only when the ion source is in operation reduces the gas load to the evacuation system and the vacuum level can be kept high. Recent experimental results will be presented.
ANL, Argonne
Northern Illinois University, DeKalb, Illinois
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC-02-06CH11357.
A prototype injector capable to produce multiple-charge-state heavy-ion beams is being developed at ANL. The injector consists of an ECR ion source, a 100 kV platform and a Low Energy Beam Transport (LEBT). The latter comprises two 60-degree bending magnets, electrostatic triplets and beam diagnostics stations. Several charge states of bismuth ions from the ECR have been extracted, accelerated to an energy of 1.8 MeV, separated and then recombined into a high quality beam ready for further acceleration. This technique allows us to double heavy-ion beam intensity in high-power driver linac for future radioactive beam facility. The other application is the post-accelerators of radioactive ions based on charge breeders. The intensity of rare isotope beams can be doubled or even tripled by the extraction and acceleration of multiple charge state beams. We will report the results of emittance measurements of multiple-charge state beams after recombination.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
During the first three years, the Spallation Neutron Source is ramping up the rep rate, pulse length, and beam current to reach 1 to 1.4 MW beam power in 2009. This challenges the Front-end with the H- source designed and built by Lawrence Berkeley National Laboratory. Early in 2007, the low-energy beam transport needed to be modified to improve the availability for duty factors in excess of 0.2%. Late in 2007, the H- source needed to be modified to produce the required 25 mA LINAC beam current during the ~0.4 ms long pulses at 60 Hz. The optimistic 1.4 MW goal requires 38 mA LINAC beam current, which was demonstrated for 4 hours on 12/24/07. LBNL developed a cesium system that uses only 30 mg of Cs to minimize the risk to the adjacent electrostatic LEBT and RFQ. Improved procedures and configuration were needed to generate intense beam currents for long pulses (>0.2 ms). Now optimal beam currents are reached within eight hours of replacing the H- source. The beam decay appears to be as small as 1% per day, which is compensated by a gradual increase in rf power. The peak performance can be restored by slowly re-cesiating the converter without interupting the neutron production.
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.
LANL, Los Alamos, New Mexico
Funding: This work was supported by the US Department of Energy under Contract Number DE-AC52-06NA25396
For the purpose of this presentation, the term Linac is narrowed down to comprise rf machines that accelerate ion beams at duty factors between about 5% and continuous operation. This group of Linacs includes proton and H- machines as well as accelerators utilizing multi-charged heavy ions, mostly for nuclear physics applications. Main types of ion sources serving these Linacs include Electron Cyclotron Resonance (ECR) sources, filament and rf driven multi-cusp sources, Penning (PIG) sources and duoplasmatrons. This presentation does not strive to attain encyclopedic character but rather to highlight current trends in performance parameters, major lines of development and type-specific limitations and problems, with emphasis on ECR and multi-cusp sources. The main technical aspects being discussed are ion production and beam formation.
TRIUMF, Vancouver
For the post acceleration of radioactive ions produced at ISOL facilities the increase of the charge state is essential to reduce the A/q requirements of the accelerators. Many of those existing or proposed facilities are relying on the performance of charge state boosters of EBIS or ECRIS type. Although, in principle both types of sources can be used in pulsed or continuous mode operation an EBIS is better suited for pulsed beams whereas an ECRIS is most efficient in a continuous mode. The present state of the art with respect to existing data of both sources will be presented and potential future developments will be discussed. Latest results from the on line commissioning of a PHOENIX ECRIS charge breeder at ISAC will be presented.