| Paper | Title | Other Keywords | Page | ||
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| MO3001 | Intense Heavy-Ion Beam Production with ECR Sources | plasma, electron, ion-source, coupling | 18 | ||
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An average increase of about one order of magnitude per decade in the performance of ECR ion sources was obtained up to now since the time of pioneering experiment of R. Geller at CEA Grenoble and this trend is not deemed to get the saturation at least in the next decade, according to the increased availability of powerful magnets and microwave generators. Electron density above 1013 cm-3 can be obtained by 28 GHz microwave heating, but only an adequate plasma trap may allow to exploit that plasma for heavy elements ionization. A study about the optimization of the magnetic field and of the other different parameters affecting the ECRIS plasma is presented, with a special emphasis on the coupling of microwaves to plasma. Long-term perspectives are presented finally, with an analysis of the possibilities opened by higher frequency generators, as 60 GHz gyro-TWTs, with the use of moderate confinement trap, by combining the large plasma density with larger escape rates in order to get larger ion beam currents.
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| MO3002 | Overview of TEM-Class Superconducting Cavities for Proton and Ion Acceleration | linac, proton, vacuum, cryogenics | 23 | ||
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Superconducting (SC) TEM-class cavities have been developed at laboratories and institututions worldwide for cw and pulsed proton and ion linac applications. New geometries spanning nearly the full velocity range from 0.1 < v/c < 0.8 include co-axial quarter- and half-wave and single- and multi-spoke cavities. Optimized designs have large beam acceptance, high shunt impedance and good microphonics properties. Rapidly evolving and improving clean surface processing techniques have been applied to TEM cavities where achieved surface fields and rf losses are comparable to the best results presently achieved in elliptical cavity designs. Recent results for a three-spoke cavity following hydrogen degassing after fabrication show very low rf losses even at high accelerating fields and now open the possibility for substantially reduced effective cryogenic load in 2 Kelvin, rather than the historically-used 4 Kelvin, operation. At present performance levels, SC TEM-class cavities constitute the technology of choice for most ion linac applications requiring cavities up to or beyond 60 percent of the speed-of-light.
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| MOP026 | Positron Source from X-rays Emitted by Plasma Betatron Motion | positron, electron, plasma, photon | 94 | ||
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A new method for generating positrons has been proposed that uses betatron X-rays emitted by an electron beam in a high-K plasma wiggler. The plasma wiggler is an ion column produced by the head of the beam when the peak beam density exceeds the plasma density. The radial electric field of the beam blows out the plasma electrons transversely, creating an ion column. The focusing electric field of the ion column causes the beam electrons to execute betatron oscillations about the ion column axis. At the proper plasma density, this leads to synchrotron radiation in the 1-50 MeV range. These photons strike a thin (.5Xo), high-Z target and create electron-positron pairs. A computational model was written and matched with experimental results taken at the Stanford Linear Accelerator Center. This model was then used to design a more efficient positron source, giving positron yields of 0.44 positrons/electron, a number that is close to the target goal of 1-2 positrons/electron for future positron sources.
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| MOP028 | Creation of Peaks in the Energy Spectrum of Laser-Produced Ions by Phase Rotation | laser, proton, target, acceleration | 97 | ||
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Efficient acceleration of ions with use of very high electromagnetic field created by a high power laser has been paid attention because of its attainable very high acceleration gradient. Its intensity, however, has exponentially decreases according to the increase of its energy, which causes essential difficulty for its real application. For the quality improvement of laser-produced ions in their energy spreads, a scheme to apply an additional RF electric field synchronous to the pulse laser, called “Phase Rotation”,* has been applied to the ions produced from the thin foil target 3 and 5 mm, in thickness by irradiation of focused Ti:Sapphire laser with the wave length of 800 nm after optimization of the ion production process with use of real time observation of ion energy by TOF measurement.** Energy peaks with the spread of 7 % have been created in the energy spectrum at the positions depending on the relative phase between the pulse laser and the RF electric field. Possible application of “Phase Rotated” laser-produced ion beam is also to be discussed.
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* A. Noda et al., Laser Physics, Vol. 16, No.4, pp.647-653(2006). |
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| MOP030 | An Upgrade to NSCL to Produce Intense Beams of Exotic Nuclei | cyclotron, linac, acceleration, injection | 103 | ||
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A substantially less costly alternative to the Rare Isotope Accelerator (RIA) project has been developed at Michigan State University (MSU). By upgrading the existing facility at the National Superconducting Cyclotron Laboratory (NSCL), it will be possible to produce stable beams of heavy ions at energies of greater than 180 MeV/u with beam power in excess of >80 kW. The upgrade will utilize a cyclotron injector and superconducting driver linac at a base frequency of 80.5 MHz. Radioactive ion beams will be produced in a high-power target via particle fragmentation. A charge-stripping foil and multiple-charge-state acceleration will be used for the heavier ions. The 9 MeV/u injector will include an ECR source, a bunching system, and the existing K1200 superconducting cyclotron with axial injection. The superconducting driver linac will largely follow that proposed by MSU for RIA, using cavities already designed, prototyped, and demonstrated for RIA. The existing A1900 Fragmentation Separator and experimental areas will be used, along with a new gas stopper and reacceleration system.
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| MOP038 | 200-MHz, 1.5-MeV Deuteron RFQ Linac | rfq, linac, ion-source, controls | 124 | ||
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A 200-MHz, 1.5-MeV deuteron RFQ linac system is under construction at Linac Systems. The linac structure employs the four-bar, radial-strut design, where the four bars are supported by a series of radial struts emanating from the wall of a cylindrical cavity with four-pole symmetry. This structure looks and performs very much like the four-vane RFQ structure. This design is about twice the efficiency of the conventional four-bar RFQ design. Another important advantage of this design is that the dipole mode is higher in frequency than the quadrupole mode, thus eliminating any problems with the mixing of the dipole mode with the quadrupole mode. Injection of deuterons into the linac will be at 50 keV from a microwave ECR ion source. The linac structure is 2.72 meters long. The peak beam current out of the linac will be 20 mA. A pulse duty factor of 5% will yield an average beam current of 1 mA. The rf power requirement is 58 kW to excite the structure, plus 30 kW to accelerate the beam, for a total of 88 kW. This linac system is scheduled for completion in the spring of 2007.
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| MOP042 | Performance of Alternating-Phase-Focused IH-DTL | linac, acceleration, rfq, heavy-ion | 136 | ||
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Tumor therapy using HIMAC has been performed at NIRS since June 1994. With the successful clinical results over more than ten years, a number of projects to construct these complexes have been proposed over the world. Since existing heavy-ion linacs are large in size, the development of compact linacs would play a key role in designing compact and cost-effective complexes. Therefore, we designed a compact injector system consisting of RFQ and Interdigital H-mode DTL (IH-DTL) having the frequency of 200 MHz. For the beam focusing of IH-DTL, the method of Alternating-Phase-Focusing (APF) was employed. By using APF, no focusing element in the cavity, such as quadrupole magnets, is needed. Having employed APF IH-DTL, the injector system is compact; the total length of two linacs is less than 6m. The injector system can accelerate carbon ions up to 4.0 AMeV. The construction and installation of RFQ and APF IH-DTL has completed, and the beam tests were performed. We succeeded to accelerate carbon ions with satisfactory beam intensity and emittances. The design and performance of RFQ and APF IH-DTL will be presented.
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| MOP043 | Upgrade of 1-MeV Heavy Ion ISR RFQ Accelerator | rfq, ion-source, simulation, acceleration | 139 | ||
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The upgrade of 1 MeV ISR RFQ accelerator has been launched for exploring the possibilities of a few mA heavy ion beam acceleration and its applications on the material science, biological irradiation and RFQ-AMS carbon chronology. A new ECR ion source with extracting voltage of 22kV, and the LEBT matching section have been redesigned and tested to increase the injection beam current and to realize the beam matching. The experimental tests for the different operating parameters have been compared to the simulations by self developed code RFQDYN. The preliminary results will be presented in this paper.
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| MOP044 | The High-Intensity Superconducting Linac for the SPIRAL 2 Project at GANIL | rfq, linac, heavy-ion, ion-source | 142 | ||
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After a detailed design study phase (2003-2004), the Spiral 2 project at GANIL was officially approved in May 2005. The project group for the construction was launched in July 2005, with the participation of French laboratories (CEA, CNRS) and international partners. The Spiral 2 Driver Accelerator is composed of an injector (protons, deuterons and heavy ions with q/A=1/3), a room temperature RFQ, and a superconducting linac with two beta families of Quarter Wave Resonators. It will deliver high intensity beams for Radioactive Ions production by the ISOL method and stable heavy ions for nuclear and interdisciplinary physics. High intensity neutrons beams will also be delivered for irradiation and time of flight experiments. In this paper we focus on the High Intensity Driver Accelerator design and the results obtained with the first prototypes of several major components.
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| MOP046 | Commissioning of the 7-MeV/u, 217-MHz Injector Linac for the Heavy Ion Cancer Therapy Facility at the University Clinics in Heidelberg | rfq, linac, ion-source, emittance | 148 | ||
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A clinical synchrotron facility designed by GSI for cancer therapy using energetic proton and ion beams (C, He and O) is under construction at the university clinics in Heidelberg, Germany. In this contribution the current status of the injector linac is reported. The installation and commissioning of the linac is performed gradually in three steps for the ion sources and the LEBT, the 400 keV/u RFQ and the 7 MeV/u IH-type drift tube linac. Two powerful 14.5 GHz permanent magnet ECR ion sources from PANTECHNIK as well as the LEBT and the linac RF system have been installed in Heidelberg between November 2005 and March 2006. A test bench with versatile beam diagnostics elements has been designed and installed for the commissioning phase. In April 2006 the two ion sources produced the first ion beams on the site. Extensive RFQ tests using proton beams have been performed at test benches at the IAP and at GSI already during 2004-2006. The 1.4 MW 217 MHz amplifier for the IH tank has also been commissioned at a test setup at GSI in advance to the installation in Heidelberg. The RF tuning of the 20 MV IH-DTL cavity is performed by the IAP in close cooperation with GSI.
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| MOP047 | An RFQ-Decelerator for HITRAP | rfq, emittance, linac, vacuum | 151 | ||
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The HITRAP linac at GSI will decelerate ions from 5 MeV/u to 6 keV/u for experiments with the large GSI Penning trap. The ions are decelerated at first in the existing experimental storage ring (ESR) down to an energy of 5 MeV/u and will be injected into a new Decelerator-Linac consisting of a IH-structure, which decelerates down to 500keV/u, and a 4-Rod RFQ , decelerating to 5 keV/u. The properties of the RFQ decelerator and the status of the project will be discussed.
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| MOP051 | Development of an Intense Neutron Source FRANZ in Frankfurt | rfq, proton, space-charge, emittance | 159 | ||
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The Stern-Gerlach-Center recently founded at the University of Frankfurt gives the possibility for experiments in accelerator physic, astrophysic and material sience research. It is planned to develop an intense neutron generator within the next 4 years. The proton driver linac consists of a high voltage terminal already under construction to provide primary proton beam energies of max. 150 keV. A volume type ion source will deliver a DC beam current of 100-250 mA at a proton fraction of 90%. A low energy beam transport using two solenoids will inject the proton beam into an RFQ while a chopper at the entrance of the RFQ will create a pulse length of 50 ns and a repetition rate up to 250 kHz. A drift tube cavity for the variation of the beam energy in a range of 1.9 – 2.4 MeV will be installed downstream of the RFQ. Finally a bunch compressor of the Mobley type forms a proton pulse length of 1 ns at the Li target. The maximum energies of the neutrons being adjustable between 100 keV and 500 keV by the primary proton beam. The detailed concept of the high current injector, numerical simulation of beam transport and losses will be presented together with first experimental results.
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| MOP052 | First Performance Test of an Integrated RFQ-Drifttube-Combination | rfq, simulation, bunching, proton | 162 | ||
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In the frame of a collaboration with the GSI in Darmstadt an RFQ-Drifttube-Combination for the Heidelberg cancer therapy center HICAT has been designed, built and successfully beam tested at the IAP Frankfurt. The integration and combination of both an RFQ and a rebunching drifttube unit inside a common cavity forming one single resonant RF-structure has been realized for the first time with this machine. The results of the beam measurements and questions about the beam dynamics simulations have been investigated in detail with the code RFQSIM.
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| MOP054 | Status of the SARAF Project | rfq, ion-source, emittance, diagnostics | 168 | ||
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Soreq NRC recently initiated the establishment of SARAF – Soreq Applied Research Accelerator Facility. SARAF will be a multi-user facility for basic, medical and biological research, non-destructive testing (NDT) and research, development and production of radio-isotopes for pharmaceutical purposes. An on going major activity is research and development of high heat flux (up to 80 kW on a few cm2) irradiation targets. SARAF is based on a continuous wave (CW), proton/deuteron RF superconducting linear accelerator with variable energy (5–40 MeV) and current (0.04-2 mA). SARAF is designed to enable hands-on maintenance, which implies beam loss below 10-5 for the entire accelerator. The commissioning of the Phase I of SARAF (full current, energy up to 4-5 MeV) is taking place during 2006 at Soreq. This paper describes the SARAF project and presents commissioning of the normal conducting injector (i.e., ECR ion source and RFQ). Test results of the β=0.09 half wave superconducting resonators are presented, and resonator geometry improvements with respect to electron multipacting behavior is discussed. An outlook on the project regarding reaching the final energy of 40 MeV is given.
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| MOP058 | Heavy-Ion-Beam Emittance Measurements at the GSI UNILAC | emittance, simulation, linac, heavy-ion | 177 | ||
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The GSI UNILAC, a linac for high current heavy ion beams, serves as an injector for the synchrotron SIS 18 and hence being a part of the future FAIR (Facility for Antiproton and Ion Research) project. The UNILAC post stripper section consists of an Alvarez accelerator with a final energy of 11.4 MeV/u. In order to meet the requirements of the FAIR project (15emA U28+, transversal normalised emittances of ex = 0.8 and ey = 2.5 mm mrad) a part of the UNILAC upgrade program is the increase of the beam brilliance. A detailed understanding of the correlation between space charge forces and focusing during acceleration of high intensity ion beams is necessary. A suited quantity to study is the beam brilliance dependency on the phase advances in the Alvarez section. Measurements are planned in 2006 and coincide with the beam dynamics work package of the European network for High Intensity Pulsed Proton Injector (HIPPI). Results of the measurements are presented as well as corresponding beam dynamics simulations.
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| MOP059 | Long-Term Perspective for the UNILAC as a High-Current, Heavy-Ion Injector for the FAIR-Accelerator Complex | heavy-ion, linac, synchrotron, ion-source | 180 | ||
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The present GSI-accelerator complex, consisting of the linear accelerator UNILAC and the heavy ion synchrotron SIS 18, is foreseen to serve as an U28+-injector for up to 10+12 particles/s for FAIR. In 2003 and 2004 different hardware measures and careful fine tuning in all sections of the UNILAC resulted in an increase of the beam intensity to 9.5·10+10 U27+ ions per 100 mks (max. pulse beam power of 0.5 MW). In addition a dedicated upgrade program for the UNILAC will be performed until 2009. It is intended to fill the SIS 18 up to the space charge limit of 2.7·10+11 U28+ ions per cycle. After completion of the FAIR complex in 2015 the running time for the accelerator facility at least will be 20 years, while the UNILAC will then be in operation for more than 60 years as a high duty factor heavy ion linac. Different proposals for a new advanced short pulse, heavy ion, high intensity, high energy linac, substituting the UNILAC as a synchrotron injector, will be discussed. This new "High Energy-UNILAC" has to meet the advanced FAIR requirements, will allow for complete multi-ion-operation and should provide for reliable beam operation in the future.
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| MOP060 | A New LEBT and RFQ Radial Matcher for the UNILAC Front End | rfq, emittance, ion-source, heavy-ion | 183 | ||
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The UNILAC heavy ion accelerator will serve as a high current injector for the future FAIR accelerator complex of GSI. This requires to inject 2.7x1011 ions/0.1x10-6s of U28+ into the existing synchrotron (SIS). Additionally, the UNILAC serves in multi beam operation experiments with high duty factor beams of different species. To meet all future demands a dedicated upgrade programme of the UNILAC is in work. This paper focuses on front end improvements. A new beam transport system will provide achromatic deflection and high mass resolution for the heavy ion beams from both existing ion source terminals. A new terminal for high current ion sources with a straight line solenoid based beam channel will be added. E.g. U3+ and U4+ ions with and a total beam current of 55mA will be injected into the RFQ for a maximum intensity yield of U4+-beam at the exit. To optimize the total front end beam transmission a redesigned radial input matcher of the RFQ is already implemented. It enables a smoother RFQ input matching of the high current beam resulting in smaller beam diameter and in lower particle losses. Beam measurements comparing old and new input radial matchers are presented.
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| MOP063 | Deceleration of Highly Charged Ions for the HITRAP Project at GSI | rfq, emittance, linac, heavy-ion | 189 | ||
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The highly charged heavy ion trap (HITRAP) project at GSI is a funded mid term project and is planned to be operational end of 2007. Highly charged ions up to U92+ provided by the GSI accelerator facility will be decelerated from 4 MeV/u down to 6 keV/u and subsequently be injected into a large Penning trap for further deceleration and phase space cooling. The deceleration is done in a combination of the GSI experimental storage ring (ESR) and a linac based on an IH-structure and a RFQ. In front of the decelerator linac a double drift-buncher-system provides for phase focusing and a final de-buncher integrated in the RFQ-tank reduces the energy spread in order to improve the efficiency for beam capture in the cooler trap. The paper reports the beam dynamics design along the entire decelerator down to the trap injection point, as well as and the status of the cavities. Finally the time schedule and ESR and linac commissioning are discussed.
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| TU1004 | Development of High-Current, High-Duty-Factor H- Injectors | emittance, SNS, electron, plasma | 213 | ||
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SNS, FNAL, and CERN have projects that require the production of H- beams with increased intensity and increased duty factors. The most demanding requirements are set by SNS, which plans to upgrade its power to 3 MW. This power level requires a LINAC peak current of 59 mA, which results from an RFQ input current between 67 and 95mA when injecting with rms-emittances between 0.20 and 0.35 Pi-mm-mrad, respectively. Predicted downstream losses exclude the use of higher emittance beams. Ion source lifetime and reliability requirements are also stringent to meet the 99.5% availability goal for the injector of a user facility with 95% availability. LEBT options are currently being studied to optimally match the ion source output into the RFQ with a minimal distortion of the beam emittance. Several ion source and LEBT options under consideration will be discussed.
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| TU2002 | Laser-Based Heavy Ion Production | laser, plasma, rfq, target | 219 | ||
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We have focused on high brightness of induced plasma in Laser Ion Source (LIS) to provide intense highly charged ions efficiently. To take the advantage of the intrinsic density of the laser plasma, Direct Plasma Injection Scheme (DPIS) has been developed. The induced laser plasma has initial expanding velocity and can be delivered directly to the RFQ. Extraction electrodes and focusing devices in LEBT are not needed. Since 2004, a newly designed RFQ has been used to verify the capability of the new ion production scheme. We succeeded to accelerate 60 m A of Carbon beam and 60 mA of Aluminium beam. We have also tried to understand plasma properties of various species by measuring charge states distributions and time structures, and are now ready to accelerate heavier species. Currently Silver 15+ beam is planned to be accelerated. In the conference, design strategies and detailed techniques for the DPIS will be described based on the measured plasma properties of various elements and new findings obtained from recent acceleration experiments. The durability and the reproducibility will be also explained.
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| TU2003 | China Spallation Neutron Source Linac Design | linac, rfq, power-supply, ion-source | 222 | ||
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Beijing Spallation Neutron Source has been approved in principle by the Chinese government. BSNS can provide a beam power of 100kW on the target in the first phase, and then 200kW in the second phase. The accelerator complex of BSNS consists of an H- linac of 81MeV and a rapid cycling synchrotron of 1.6GeV at 25Hz repetition rate. In the second phase, the linac energy will be upgraded to 134MeV and the average current will be doubled. The linac has been designed, and some R&D studies have been lunched under the support from Chinese Academy of Sciences. The linac comprises a H- ion source, an RFQ and a conventional DTL with EMQs. This paper will present our major design results and some progresses in the R&D of the linac.
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| TU2004 | Results on the Beam Commissioning of the Superconducting-RFQ of the New LNL Injector | rfq, emittance, simulation, beam-losses | 227 | ||
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A new injector for the heavy ion superconducting linac ALPI has been built at LNL. This new accelerator, named PIAVE, is designed to accelerate ions with A/Q=<8.5 up to 1.2 MeV/u. The main components are an ECRIS source operating on a high voltage platform, a three harmonic buncher, a superconducting RFQ cryomodule containing two bulk niobium structures and two QWR cryomodules housing 4 cavities each. In the last year the injector has been commissioned, with O, Ar, Ne and Xe beams, and put into operation. The beam performances, and the results of longitudinal and transverse emittance measurements will be shown and compared with simulations. Neon and argon beams have been delivered to the experiments (after acceleration with PIAVE and ALPI) for a total of about 400 hours. It should be noted that this is the first superconducting RFQ in operation; the design opportunities offered by this technology for a wider field of applications will be briefly discussed. The heart of these opportunity is given by the high intervane voltage in a cw RFQ (PIAVE can operate cw with an intervane voltage higher than 250 kV).
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| TU3001 | High-Current Proton Beam Investigations at the SILHI-LEBT at CEA/Saclay | emittance, proton, space-charge, ion-source | 232 | ||
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For the injection of a high current proton beam into the future proton LINAC at GSI for FAIR the ion source and the low energy beam transport system have to deliver a 100 mA proton beam with an energy of 95 keV within an acceptance of 0.3 mm mrad (normalized, rms) at the entrance of the RFQ. Besides the ion source a 2-solenoid focusing system is foreseen as an injection scheme for the subsequent RFQ. The beam parameters of the SILHI ion source and the 2-solenoid LEBT setup generally meet these requirements. Therefore joint emittance measurements on various beam parameters have been performed at the end of the LEBT system. In the frame work of the design study for the future proton LINAC it was a unique possibility to investigate the injection of a high current proton beam into a low energy beam transport system under the influence of space charge. The measurements reveal that a proton current of 100 mA can be achieved at the end of the LEBT while the emittance (95 %, rms, normalized) is as high as 0.3 to 0.5 mm mrad.
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| TUP005 | Design of an RFQ-Based Neutron Source for Cargo Container Interrogation | rfq, target, ion-source, quadrupole | 253 | ||
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An RFQ-based neutron generator system is described that generates pulsed neutrons for the active screening of sea-land cargo containers for the detection of shielded special nuclear materials (SNM). A microwave-driven deuteron source is coupled to an electrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1 meter-long 200 MHz RFQ. The RFQ has a unique beam dynamics design and is capable of operating at duty factors of 5 to10% accelerating a D+ time-averaged current of up to 1.5 mA at 5% duty factor, including species and transmission loss. The beam is transported through a specially-designed thin-window into a 2-atmosphere deuterium gas target. A high-frequency dipole magnet is used to scan the beam over the long dimension of the 5 by 40 cm target window. The source will be capable of delivering a neutron flux of 2·107 n/(cm2·s) to the center of a cargo container. Details of the ion source, LEBT, RFQ beam dynamics and gas target design are presented.
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| TUP029 | Performance and Early Operating Experience with the ISAC-II Cryogenic System | linac, cryogenics, vacuum, controls | 306 | ||
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A 500 W class refrigerator has been installed and commissioned at TRIUMF to cool the new 20MV superconducting linac. The refrigerator liquifies helium into a common supply dewar. The dewar feeds a common cold manifold and the five cryomodules are fed via parallel cold distribution circuits. The system operates at 4.5K. Measurements have been done to estimate the static loads of the cryomodules and the distribution system and to characterize plant performance. The paper will include a system description, performance results and early operating experience.
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| TUP037 | Possible Upgrade Paths for the LANSCE H- Injector | rfq, ion-source, linac, target | 330 | ||
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The LANSCE linac presently provides both H- and H+ beams to several user facilities. The H- injector uses a cesiated, multi-cusp field, surface converter source operating at duty factors between 10 and 12%, coupled to a Cockcroft-Walton (CW) accelerator to provide peak beam currents of ~15 mA for the LANSCE linac. In an effort to raise the peak beam current available to the majority of the H- users, we are pursuing two options. The first is a low duty factor H- ion source and a 750 keV RFQ that would provide ~25 mA of peak current for use by the Lujan and pRad programs. The second is a low frequency buncher for the existing 80 keV beam transport located inside the CW dome that could provide about a factor of two increase in the peak beam current for the WNR program. This paper will present these two options.
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| TUP039 | Two-Charge-State Injector for a High Power Heavy-Ion Linac* | emittance, linac, heavy-ion, rfq | 336 | ||
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A permanent magnet (PM) ECR ion source and following low energy beam transport (LEBT) system with the capability to deliver two-charge-state heavy-ion beams (2Q-LEBT) for high-power linacs is being prototyped at Argonne. The injector consists of the PM ECR ion source, transport line with beam diagnostics including emittance measurements and a multi-harmonic buncher. Recently the ECR ion source has been installed on a high voltage platform to increase the accelerating voltage up to the design value of 100 kV. The unique feature of the 2Q-LEBT layout is that the charge separation is performed off of the platform after acceleration of a multi-component ion beam. This layout allows us to analyze and recombine two-charge-state beams using an achromatic bending system. Improvements of the PM ECR performance and beam optics studies based on measurements of various heavy-ion beams will be discussed in this paper.
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*This work was supported by the U. S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38 |
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| TUP040 | Progress on a Cryogenically Cooled RF Gun Polarized Electron Source | gun, cathode, vacuum, electron | 339 | ||
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RF guns have proven useful in multiple accelerator applications. An RF gun capable of producing polarized electrons is an attractive electron source for the ILC or an electron-ion collider. Producing such a gun has proven elusive. The NEA GaAs photocathode needed for polarized electron production is damaged by the vacuum environment in an RF gun. Electron and ion backbombardment can also damage the cathode. These problems must be mitigated before producing an RF gun polarized electron source. In this paper we report continuing efforts to improve the vacuum environment in a normal conducting RF gun by cooling it with liquid Nitrogen after a high temperature vacuum bakeout. We also report on a design of a cathode preparation chamber to produce bulk GaAs photocathodes for testing in such a gun. Future directions are also discussed.
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| TUP042 | A Proposal for Post Acceleration, Matching and Measuring the H- Ion Beam at CERN's Linac 4 Test Stand | emittance, linac, simulation, rfq | 343 | ||
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CERN's proposed future Linac 4 is a 160 MeV H- Linac injecting into the Proton Sychrotron Booster. We propose that the ion source parameters (80mA, 500us pulse length, 2Hz repetition rate, 0.25 mm.mrad normalised emittance at 1 σ) may be achieved by improving an existing 2MHz RF multicusp source. In this report, we explain the proposal to post-accelerate the beam from 35keV to 95keV, and to focus the beam into the RFQ with solenoids, with the aimof avoiding substantial emittance growth. Finally, details of the diagnostics required to test the source are given.
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| TUP046 | Experimental Studies of Electrostatic and Solenoidal Focusing of Low-Energy, Heavy-Ion ECRIS Beams at the NSCL/MSU | emittance, dipole, focusing, injection | 352 | ||
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Replacement of the focusing solenoids between both ECR Ion Sources and the beam analysis dipoles with electrostatic triplets has resulted in a large increase in net accelerator output. 2D emittance scans explain some but not all of this increase. Further improvement is anticipated with a new optical device consisting of an electrostatic quadrupole doublet-octupole-doublet-magnetic sextupole arrangement, which has been built and is being tested in place of a triplet. Motivations and results of measurements and operating experience are discussed.
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| TUP053 | Initial Tests of an Elemental Cs-System for the SNS Ion Source | SNS, ion-source, plasma, injection | 364 | ||
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The ion source employed in the Spallation Neutron Source* (SNS) is an RF-driven, Cs-enhanced, multi-cusp H- source. To date, the source has been successfully utilized in the commissioning of the SNS accelerator producing 10–40 mA. Presently, Cs is dispensed within the source using Cs2CrO4 cartridges located in an air heated/cooled cylindrical collar surrounding the outlet aperture. The temperature of the collar is elevated to release Cs into the source. Typically, this process can only be repeated 2-3 times before the Cs is depleted and the source needs to be replaced. In addition, the dispensers are subject to poisoning by the residual gases in the source leading to beam decay. This is especially problematic at high duty-factor. This report describes the design of an elemental Cs system incorporating an external reservoir based on the proven Fermilab system. Source performance is characterized and compared for both the original and the elemental Cs systems.
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| TUP054 | A Proposed Helicon Driver for the SNS Ion Source | plasma, SNS, ion-source, extraction | 367 | ||
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The H- ion source employed in the Spallation Neutron Source* (SNS) is an RF-driven, multi-cusp source, which utilizes a helical antenna to inductively couple power into the source plasma. To date, the source has been successfully utilized in the commissioning of the SNS accelerator producing 10–40 mA of H- with duty-factors of ~0.1%. Ultimately, the SNS facility will require beam duty-factors of 6% and ~60 mA of H- injecting the linac. This may require currents of up to ~100 mA from the source depending on the ion source emittance. To date, the SNS source has only delivered sustained currents of ~33 mA at full duty factor. Therefore, we are developing plasma generators capable of achieving much higher plasma densities. Plasmas generated through helicon-wave coupling can develop densities up to 100 times greater than those produced by conventional inductive coupling. This report presents an initial design and discusses considerations for a source which combines the forward portion of the SNS source with a helicon system. The helicon system consists largely of components retrofitted from the proven hydrogen VASIMR system employed in space propulsion.
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| TUP055 | A Plasma Gun Driver for the SNS Ion Source | plasma, gun, ion-source, SNS | 370 | ||
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The ion source developed for the Spallation Neutron Source (SNS) is an RF-driven, multi-cusp source designed to produce ~ 40 mA of H- with a normalized rms emittance of less than 0.2 π mm mrad. To date, the source has been successfully utilized in the commissioning of the SNS accelerator producing 10–40 mA of H- with duty-factors of ~0.1%. Recently, we found the H- yield from the source could be increased dramatically with the introduction of streaming plasma particles injected into the primary RF plasma from a hemispherical glow discharge chamber located in the rear of the source. In some cases, a 50% increase in the H- beam current was observed. The system also eliminated the need for other plasma ignition systems like a secondary low-power RF generator. This report details the design of the plasma gun as well as the parametric dependence of H- current on source operating conditions. Comparisons are made with and without the gun energized. Finally, an off-line test stand was employed to characterize the plasma current emitted directly from the gun as well as perform lifetime characterization.
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SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U. S. Department of Energy. |
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| TUP056 | The Development of a High-Power, H- Ion Source for the SNS-Based on an External Antenna | plasma, SNS, ion-source, gun | 373 | ||
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The ion source developed for the Spallation Neutron Source* (SNS) is a radio frequency, multi-cusp H- source, which utilizes an internal antenna immersed within the source plasma. To date, the source has been utilized successfully in commissioning of the SNS accelerator delivering 10 - 40 mA with duty-factors of ~0.1% for periods of several weeks. Ultimately, the SNS facility will require beam currents of ~60 mA at 6% duty-factor. Tests have shown that the internal antenna is susceptible to failure at this duty-factor. Currently, two ion sources are being developed which feature ceramic plasma chambers surrounded by an external antenna. The first is a low-power, test version which employs a high-inductance external antenna and produces considerably higher H- beam currents than the original SNS source when both are operated without Cs. The second is a high-power version which features a Faraday shield with an integrated magnetic confinement structure and is designed to operate at full duty factor. The performance of this source should also greatly exceed that of the present SNS source. Details of the design and the measured performance of each source are discussed.
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| TUP060 | Status of the EBIS Project at Brookhaven | rfq, electron, linac, injection | 385 | ||
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The EBIS Project at Brookhaven National Laboratory will replace the Tandem Van de Graaff accelerators with an Electron Beam Ion Source, an RFQ, and short linac, as the heavy ion preinjector for RHIC. This project, jointly funded by DOE and NASA, will provide a modern preinjector which will have increased flexibility in providing beams to the various programs running simultaneously, will be capable of providing beams not presently available for RHIC and the NASA Space Radiation Laboratory, and will be simpler and less costly to operate. Presently in the first year of the four-year project, the detailed design is nearly complete, and some major procurements have been placed. The overall status of the project will be presented, as well as some unique features in the design, and results from the R&D using the prototype EBIS.
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| TUP066 | Particle Dynamics Calculations and Emittance Measurements at the FETS | simulation, rfq, emittance, ion-source | 403 | ||
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High power proton accelerators in the MW range have many applications including drivers for spallation neutron sources, neutrino factories, transmuters (for transmuting long-lived nuclear waste products) and energy amplifiers. In order to contribute to the development of HPPAs, 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 front end test stand is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. An overview on the status of the project together with the results of numerical simulations of the particle dynamics from the ion source to the RFQ exit will be presented. The particle distributions gained from the particle dynamics simulations will be compared with recent measurements of the transversal beam emittance behind the ion source and the results discussed.
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| TUP078 | Status of the End-to-End Beam Dynamics Simulations for the GSI UNILAC | rfq, simulation, emittance, synchrotron | 438 | ||
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The heavy ion high current GSI linac UNILAC serves as an injector for the synchrotron SIS18. The UNILAC mainly consists of a High Current Injector (HSI), the stripper section at 1.4 MeV/u, and the Alvarez postaccelerator (11.4 MeV/u). During the last years the systematic experimental and numerical studies resulted in an increase of the U73+ beam intensity of up to a factor of seven. The needs of the FAIR project (Facility for Antiproton and Ion Research at Darmstadt) require further improvement of the beam brilliance coming from UNILAC up to a factor of five. End-to-end beam dynamics simulations with the DYNAMION code have already been started. The general goal is to establish a simulation tool which can calculate the impact of the planned upgrade measures on the performance of the whole UNILAC. The results of the HSI calculations including influence of the beam intensity on the beam parameters (current, emittance, Twiss-parameters) at the stripper section are presented. Recent calculations and measurements of the beam matching to the Alvarez section under space charge conditions are discussed in the paper.
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| TUP081 | Impact of a RF Frequency Change on the Longitudinal Beam Dynamics | linac, emittance, focusing, acceleration | 447 | ||
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A frequency jump in a high-intensity linac could have some impact on the longitudinal beam dynamics and could therefore introduce some filamentation and even some beam loss if the transition is not done properly. This point is especially important when comparisons of cavity performances are performed. We show in this paper two techniques in order to render transparent for the beam such frequency jump. A few examples which show the efficiency of the two techniques are given.
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| TUP085 | Beam Simulations for the MSU-RIA Driver Linac Using IMPACT Code | linac, simulation, beam-losses, emittance | 457 | ||
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Previous end-to-end three-dimensional (3D) beam dynamics simulation studies at Michigan State University (MSU) utilizing the LANA code and including experimentally-based ion source beam parameters, alignment and rf errors, and the effect of charge-stripping foils have indicated that the MSU Rare Isotope Accelerator (RIA) driver linac has adequate transverse and longitudinal acceptances to accelerate light and heavy ions to final energies of ≥ 400 MeV/u with beam powers of 100 to 400 kW. Recently, to evaluate beam dynamics performance under various error scenarios with high statistics, the end-to-end 3D beam dynamics simulation studies for the driver linac were performed on the high performance parallel computers at MSU using the parallel code IMPACT that is an element of the advanced beam dynamics simulation tool: RIAPMTQ/IMPACT. The results of these beam dynamics studies will be presented.
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| TUP087 | Ion Charge Stripping Foil Model for Beam Dynamics Simulation | simulation, linac, scattering, heavy-ion | 463 | ||
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An efficient computer model for the stripping foil simulation was proposed at NSCL/MSU as part of the Rare Isotope Accelerator (RIA) development. The model was successfully implemented in the LANA beam dynamics simulation code. Later this model was also included in the IMPACT code as well as in some other beam dynamics simulation tools. The derivation of the algorithm is presented and the application of the model for the uranium beam stripping simulation in context of the RIA driver linac studies at NSCL/MSU is analysed in the paper.
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| TUP089 | Computer Simulations of a High-Current Proton Beam at the SILHI-LEBT | emittance, proton, simulation, space-charge | 469 | ||
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For the injection of a proton beam into the future proton LINAC for FAIR the ion source and the low energy beam transport system have to deliver a 100 mA proton beam with an energy of 95 keV at the entrance of the RFQ within an acceptance of 0.3 π mm mrad (normalized, rms). A 2-solenoid focusing system is foreseen as an injection scheme. The beam parameters of the SILHI ion source and the 2-solenoid LEBT setup at CEA/Saclay fulfill these requirements. Therefore joint emittance measurements on various beam parameters have been performed at the end of 2005. This article presents the computer simulations of the ion source extraction and LEBT, which supplemented these measurements using the KOBRA3-INP computer code in order to study the influence of space charge effects. These simulations have been performed for various solenoid settings and for different space charge compensation degrees clearly revealing that the ion beam transport within the LEBT is influenced by space charge forces.
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| WE2001 | Neutralized Drift Compression Experiments (NDCX) | plasma, simulation, vacuum, acceleration | 492 | ||
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Intense ion beams offer an attractive approach to heating dense matter uniformly to extreme conditions, because their energy deposition is nearly classical and volumetric. Simultaneous transverse and longitudinal beam compression, in a neutralizing plasma medium, along with rapid beam acceleration, are being studied as a means of generating such beams, which will be used for warm dense matter (WDM), high energy density physics (HEDP), and fusion studies. Recently completed experiments on radial and longitudinal compression demonstrated significant enhancements in beam intensity. In parallel with beam compression studies, a new accelerator concept, the Pulse Line Ion Accelerator (PLIA), potentially offers cost-effective high-gradient ion beam acceleration at high line charge density. We report experimental results on beam neutralization, neutralized focusing, neutralized drift compression from a series of experiments. We also report energy gain and beam bunching in the first beam dynamics validation experiments exploring the PLIA.
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| TH1003 | Initial Commissioning Results from the ISAC-II SC Linac | linac, acceleration, emittance, heavy-ion | 521 | ||
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TRIUMF has installed 20MV of superconducting heavy ion linac as part of the first phase of the ISAC-II project. The linac consists of five cryomodules each with four 106MHz quarter wave cavities and one superconducting solenoid. The cavities and ancillaries operate cw with a demonstrated peak surface field exceeding 30MV/m at 7W rf cavity power. The solenoid produces fields up to 9T. In an initial beam test with a single module cavity performance exceeded design by over 20%. The full linac was installed by early 2006 with full linac beam commissioning tests starting in April 2006. The linac hardware will be described and the commissioning tests and results will be summarized.
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| THP039 | Status of the RF Systems for the SPIRAL2 Linac at the Beginning of the Construction Phase | controls, rfq, linac, diagnostics | 664 | ||
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The Spiral 2 project uses an RFQ and a superconductiong linac to accelerate high intensity beams of deuterons and heavier ions. The accelatoror frequency is 88 MHz. The construction phase was approved in Mai 2005 and the project organization was recently finalized. The RF Systems activity includes power amplifiers and control electronics for all the accelerator and some of the RF devices on the beam line: the slow and fast chopper and the rebunchers. The paper describes the status of the amplifiers prototypes, the architecture chosen for the digital LLRF and the preliminary studies on the other RF devices.
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| THP042 | Development of High-Current 201.5-MHz Deuteron RFQ Accelerator | rfq, simulation, linac, ion-source | 673 | ||
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The beam dynamics for a 201.5MHz 50mA 2.0MeV Deuteron RFQ accelerator with duty cycle of 10% has been further improved by using equipartitioning method. The RFQ structure, mechanical design, thermal analysis and its cooling method have been investigated. The tuning of RF cavity for the field and other parameters has been simulated. A new developed ECR ion source and its setup have been completed and tested. The LEBT for the injection of RFQ is under the construction, and the HEBT at RFQ exit for the further applications has been designed and to be constructed in the near future. All the development results will be presented in this paper.
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| THP063 | First High-Power ACS Module for J-PARC Linac | linac, vacuum, pick-up, resonance | 725 | ||
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J-PARC Linac will be commissioned with energy of 181-MeV using 50-keV ion source, 3-MeV RFQ, 50-MeV DTL and 181-MeV SDTL (Separated DTL) on December 2006. It is planed to be upgraded by using 400-MeV ACS (Annular Coupled Structure), in a few years from the commissioning. The first high-power ACS module, which will be used as the first buncher between the SDTL and the ACS has been fabricated, and a few accelerating modules are also under fabrication until FY2006. Detail of cavity design and tuning procedure has been studied with RF simulation analysis and cold-model measurements. This paper describes RF measurement results, fabrication status, and related development items.
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| THP089 | Testbench of the HICAT RFQ at GSI | rfq, linac, proton, RF-structure | 791 | ||
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In April 2006 the commissioning of the ion linac for the HICAT therapy facility in Heidelberg, Germany was started. In preparation of this commissioning process beam tests of the RFQ cavity with protons were carried out at GSI. The RFQ cavity for the HICAT facility was delivered to GSI in March 2005. The operation with an rf power up to 200 kW and a pulse width of 500 μsec could be accomplished successfully after a short time of rf-conditioning to assure the operation mode with carbon ions. A testbench for the RFQ cavity was constructed at GSI to allow for exact measurements of the output energy with the time of flight (ToF) method in addition to the beam tests at IAP Frankfurt. Due to the fact that the rebuncher is fully integrated into the RFQ rf-structure beam studies with different mechanical settings of the rebuncher had to be conducted. For each setting the effective voltage of the rebuncher could be estimated. The final mechanical setting was chosen with respect to required longitudinal matching to the IH structure behind of the RFQ.
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| FR2001 | Targets and Ion Sources Development at ISAC-TRIUMF | target, ion-source, laser, proton | 823 | ||
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The ISAC facility is operational since 1998, we utilize the proton beam from the TRIUMF H- cyclotron to produce the radioactive ion beams (RIB) via the isotopic separation on line (ISOL) method. The ISAC facility is designed to accommodate 100 μA proton beam at 500 MeV. Since beginning operation irradiation currents have progressively increased from initial values of ~ 1 μA to present levels of up to 75 μA on refractory metal foil targets and recently equally on composite carbide targets. Beyond the 50 μA limit the target has to be cooled. A new target equipped with fins has been developed that can sustain proton beam up to 100 μA. The RIB intensities depend not only on the target but also on the ability to produce ion beam. The ion sources design for on-line applications are extremely important because of the close contact with the target. They must sustain high radiation field and operate in a large gas pressure range. In order to produce a larger range of beam we are looking at other types, ECR, FEBIAD, negative and the laser ion sources. Report on the recent progress accomplished during the past years will be made.
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