The Facility for Rare Isotope Beams (FRIB), under construction at Michigan State University, will... more The Facility for Rare Isotope Beams (FRIB), under construction at Michigan State University, will utilize a driver linac to accelerate stable ion beams from protons to uranium up to energies of >200 MeV per nucleon with a beam power of up to 400 kW. The FRIB linac consists of 46 cryomodules containing a total of 324 superconducting radio-frequency (SRF) resonators and 69 superconducting solenoids. The design of all six type cryomodules has been completed. The critical SRF components are tested as subsystem and validated in the pre-production cryomodules. The mass production of SRF cryomodules is underway. Here we report on the progress of the technical construction of FRIB superconducting linac.
The driver linac for the Facility for Rare Isotope Beams (FRIB) comprises four kinds of cavities ... more The driver linac for the Facility for Rare Isotope Beams (FRIB) comprises four kinds of cavities (β=0.041, 0.085, 0.29, and 0.53) and six types of cryomodules including matching modules. FRIB has completed the fabrication and the cold test of a β=0.53 pre-production cryomodule, which is the first prototype for a half-wave (β=0.29 and 0.53) cavity. This paper describes the fabrication and the cold test result of the β=0.53 pre-production cryomodule including lessons learned.
The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operatin... more The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operating at frequencies from 80.5 MHz to 322 MHz. Much higher power is required for the normal conducting RFQ, ~100 kW, and it is based on vacuum tubes. This invited talk presents the performance of solid state amplifiers and LLRF in off-line testing and on-line testing of the RFQ amplifier.
The driver linac for the Facility for Rare Isotope Beams (FRIB) will require the production of 48... more The driver linac for the Facility for Rare Isotope Beams (FRIB) will require the production of 48 cryomodules. FRIB has completed the fabrication and testing of a β=0.085 quarter-wave cryomodule as a pre-production prototype. This cryomodule qualified the performance of the resonators, fundamental power couplers, tuners, and cryogenic systems of the β=0.085 quarter-wave design. In addition to the successful systems qualification; the ReA6 cryomodule build also verified the FRIB bottom up assembly and alignment method. The lessons learned from the ReA6 cryomodule build, as well as valuable fabrication, sourcing, and assembly experience are applied to the design and fabrication of FRIB production cryomodules. This paper will report the results of the β=0.085 quarter-wave cryomodule testing, fabrication, and assembly; production implications to future cryomodules will also be presented. INTRODUCTION FRIB is a high-power heavy ion accelerator facility now under construction at Michigan ...
The FRIB driver linac accelerates all the stable ion beams including uranium over 200 MeV/u with ... more The FRIB driver linac accelerates all the stable ion beams including uranium over 200 MeV/u with a CW beam power of 400 kW in order to produce isotopes as rare as possible. Except for 0.5 MeV/u RFQ, the linac is making use of superconducting (SC) RF technology. The beam power, which is an order of 2.5 as high as those of existing SC heavy ion linac, gives rise to many technical challenges as well as beam physics related ones. In particular, the uranium beam loss power density is approximately 30 times as high as the proton one with the same beam energy per nucleon and the same beam power. For this reason, the machine protection system needs a special care. Another example of the technical challenges is to install beam focusing solenoid as close as possible to SC cavities in order to keep the beam focusing as frequent as possible both longitudinally and transversely. This paper reviews all these challenges with development results of their mitigation as well as construction status.
The Facility for Rare Isotope Beams (FRIB) at Michigan State University will provide intense beam... more The Facility for Rare Isotope Beams (FRIB) at Michigan State University will provide intense beams of rare isotopes for research in nuclear physics, nuclear astrophysics and study of fundamental interactions. A Superconducting linac will accelerate the primary beam to energies beyond 200 Mev/u and is designed to reach a maximum beam power close to 400kW on the fragmentation target. In the case of Uranium about 13.3 pμA of U33+ are needed from the ion source to reach this maximum beam power on target. An ECR ion source operating at 28 GHz and based on the VENUS ion source developed at Lawrence Berkeley National Laboratory (LBNL) is currently being designed to meet the project intensity requirement and is presented in this paper. Although the intensity requirement from the ion source are very high for the FRIB project, new results have been obtained recently with VENUS that demonstrate that this ion source can actually produce close to 13pμA of U33+ within the emittance required by th...
The Facility of Rare Isotope Beams (FRIB) project was presented in SRF2013 [1]. This paper report... more The Facility of Rare Isotope Beams (FRIB) project was presented in SRF2013 [1]. This paper reports the progressed situation of this project since SRF2013. FRIB project is now moving to production phase. FRIB superconducting RF (SRF) linac project and challenges are presented. This paper address the status of the SRF hardware production, SRF infrastructure status and plans for ramping to full production, and also focus on information that can be relevant for future large proton/ion SRF linac projects.
The Facility for Rare Isotope Beams (FRIB) driver linac will deliver all stable heavy ion beams w... more The Facility for Rare Isotope Beams (FRIB) driver linac will deliver all stable heavy ion beams with energy more than 200 MeV/u and beam power on target up to 400 kW. Since FRIB is the first SRF linac for high power heavy ion beams, design and integration of the accelerator components are important and there are many challenges. Several issues on design and integration of the linacare introduced and studies which include developments of the accelerator online model, minimize uncontrolled beam loss, beam diagnostic systems for linac beam tuning and for machine protection system (MPS), appropriate degauss process with SC solenoids in cryomodules, RF system, vacuum system and cryogenic system are briefly discussed in this paper.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014
The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. D... more The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.
The Facility for Rare Isotope Beams (FRIB), under construction at Michigan State University, will... more The Facility for Rare Isotope Beams (FRIB), under construction at Michigan State University, will utilize a driver linac to accelerate stable ion beams from protons to uranium up to energies of >200 MeV per nucleon with a beam power of up to 400 kW. The FRIB linac consists of 46 cryomodules containing a total of 324 superconducting radio-frequency (SRF) resonators and 69 superconducting solenoids. The design of all six type cryomodules has been completed. The critical SRF components are tested as subsystem and validated in the pre-production cryomodules. The mass production of SRF cryomodules is underway. Here we report on the progress of the technical construction of FRIB superconducting linac.
The driver linac for the Facility for Rare Isotope Beams (FRIB) comprises four kinds of cavities ... more The driver linac for the Facility for Rare Isotope Beams (FRIB) comprises four kinds of cavities (β=0.041, 0.085, 0.29, and 0.53) and six types of cryomodules including matching modules. FRIB has completed the fabrication and the cold test of a β=0.53 pre-production cryomodule, which is the first prototype for a half-wave (β=0.29 and 0.53) cavity. This paper describes the fabrication and the cold test result of the β=0.53 pre-production cryomodule including lessons learned.
The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operatin... more The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operating at frequencies from 80.5 MHz to 322 MHz. Much higher power is required for the normal conducting RFQ, ~100 kW, and it is based on vacuum tubes. This invited talk presents the performance of solid state amplifiers and LLRF in off-line testing and on-line testing of the RFQ amplifier.
The driver linac for the Facility for Rare Isotope Beams (FRIB) will require the production of 48... more The driver linac for the Facility for Rare Isotope Beams (FRIB) will require the production of 48 cryomodules. FRIB has completed the fabrication and testing of a β=0.085 quarter-wave cryomodule as a pre-production prototype. This cryomodule qualified the performance of the resonators, fundamental power couplers, tuners, and cryogenic systems of the β=0.085 quarter-wave design. In addition to the successful systems qualification; the ReA6 cryomodule build also verified the FRIB bottom up assembly and alignment method. The lessons learned from the ReA6 cryomodule build, as well as valuable fabrication, sourcing, and assembly experience are applied to the design and fabrication of FRIB production cryomodules. This paper will report the results of the β=0.085 quarter-wave cryomodule testing, fabrication, and assembly; production implications to future cryomodules will also be presented. INTRODUCTION FRIB is a high-power heavy ion accelerator facility now under construction at Michigan ...
The FRIB driver linac accelerates all the stable ion beams including uranium over 200 MeV/u with ... more The FRIB driver linac accelerates all the stable ion beams including uranium over 200 MeV/u with a CW beam power of 400 kW in order to produce isotopes as rare as possible. Except for 0.5 MeV/u RFQ, the linac is making use of superconducting (SC) RF technology. The beam power, which is an order of 2.5 as high as those of existing SC heavy ion linac, gives rise to many technical challenges as well as beam physics related ones. In particular, the uranium beam loss power density is approximately 30 times as high as the proton one with the same beam energy per nucleon and the same beam power. For this reason, the machine protection system needs a special care. Another example of the technical challenges is to install beam focusing solenoid as close as possible to SC cavities in order to keep the beam focusing as frequent as possible both longitudinally and transversely. This paper reviews all these challenges with development results of their mitigation as well as construction status.
The Facility for Rare Isotope Beams (FRIB) at Michigan State University will provide intense beam... more The Facility for Rare Isotope Beams (FRIB) at Michigan State University will provide intense beams of rare isotopes for research in nuclear physics, nuclear astrophysics and study of fundamental interactions. A Superconducting linac will accelerate the primary beam to energies beyond 200 Mev/u and is designed to reach a maximum beam power close to 400kW on the fragmentation target. In the case of Uranium about 13.3 pμA of U33+ are needed from the ion source to reach this maximum beam power on target. An ECR ion source operating at 28 GHz and based on the VENUS ion source developed at Lawrence Berkeley National Laboratory (LBNL) is currently being designed to meet the project intensity requirement and is presented in this paper. Although the intensity requirement from the ion source are very high for the FRIB project, new results have been obtained recently with VENUS that demonstrate that this ion source can actually produce close to 13pμA of U33+ within the emittance required by th...
The Facility of Rare Isotope Beams (FRIB) project was presented in SRF2013 [1]. This paper report... more The Facility of Rare Isotope Beams (FRIB) project was presented in SRF2013 [1]. This paper reports the progressed situation of this project since SRF2013. FRIB project is now moving to production phase. FRIB superconducting RF (SRF) linac project and challenges are presented. This paper address the status of the SRF hardware production, SRF infrastructure status and plans for ramping to full production, and also focus on information that can be relevant for future large proton/ion SRF linac projects.
The Facility for Rare Isotope Beams (FRIB) driver linac will deliver all stable heavy ion beams w... more The Facility for Rare Isotope Beams (FRIB) driver linac will deliver all stable heavy ion beams with energy more than 200 MeV/u and beam power on target up to 400 kW. Since FRIB is the first SRF linac for high power heavy ion beams, design and integration of the accelerator components are important and there are many challenges. Several issues on design and integration of the linacare introduced and studies which include developments of the accelerator online model, minimize uncontrolled beam loss, beam diagnostic systems for linac beam tuning and for machine protection system (MPS), appropriate degauss process with SC solenoids in cryomodules, RF system, vacuum system and cryogenic system are briefly discussed in this paper.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014
The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. D... more The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.
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Papers by Nathan Bultman