To the transverse beam collimation system in a rapid cycling synchrotron,an important component is the primary collimator,which improves emittance of the beam halo particles such that the particles outside the predefi...To the transverse beam collimation system in a rapid cycling synchrotron,an important component is the primary collimator,which improves emittance of the beam halo particles such that the particles outside the predefined trajectory can be absorbed by the secondary collimators.Given the material properties and power deposition distribution,the beam scraper of the primary collimator is a0.17 mm tungsten foil on a double face-wedged copper block of 121.5 mm x 20 mm.The heat is transferred to the outside by a φ34 mm copper rod.In this paper,for minimizing brazing thermal stress,we report our theoretical analysis and tests on brazing the tungsten and copper materials which differ greatly in size.We show that the thermal stress effect can be controlled effectively by creating stress relief grooves on the copper block and inserting a tungsten transition layer into the copper block.This innovation contributes to the successful R&D of the primary collimator.And this study may be of help for working out a brazing plan of similar structures.展开更多
The Robust Conjugate Direction Search（RCDS） method is used to optimize the collimation system for the Rapid Cycling Synchrotron（RCS） of the China Spallation Neutron Source（CSNS）. The parameters of secondary coll...The Robust Conjugate Direction Search（RCDS） method is used to optimize the collimation system for the Rapid Cycling Synchrotron（RCS） of the China Spallation Neutron Source（CSNS）. The parameters of secondary collimators are optimized for a better performance of the collimation system. To improve the efficiency of the optimization, the Objective Ring Beam Injection and Tracking（ORBIT） parallel module combined with MATLAB parallel computing is used, which can run multiple ORBIT instances simultaneously. This study presents a way to find an optimal parameter combination of the secondary collimators for a machine model in preparation for CSNS/RCS commissioning.展开更多
According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing...According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing,in which the thickness of tungsten slice is 0.17 mm.In order to get the best mechanical properties,the brazing temperature is suggested to be controlled under the recrystallization temperature of tungsten,while the recrystallization temperature is affected directly by the thickness of tungsten.Because of little research and application on the brazing of thin tungsten slice of 0.17 mm and copper,tensile tests are done to get the mechanical properties of tungsten slices which experience different brazing temperatures.In keeping the inner relationships between the mechanical properties and temperature,another experiment is done by using SEM to scan the microstructures including the size and distribution of crystals.Finally we determine the recrystallization temperature of tungsten slice of 0.17 mm,and get the best parameters of W/Cu brazing for scrapers of primary collimator in CSNS/RCS.展开更多
The rapid cycling synchrotron （RCS） is part of the China Spallation Neutron Source （CSNS）. The RCS provides 1.6 GeV protons with a repetition rate of 25 Hz. The RF system in RCS is mainly composed of a ferrite loa...The rapid cycling synchrotron （RCS） is part of the China Spallation Neutron Source （CSNS）. The RCS provides 1.6 GeV protons with a repetition rate of 25 Hz. The RF system in RCS is mainly composed of a ferrite loaded RF cavity, a high power tetrode amplifier, a bias supply of 3300 A and a digital low level RF （LLRF） system based on FPGA. The major challenge of the LLRF system is to solve problems caused by rapid frequency sweeping and the heavy beam loading effect. A total of eight control loops are applied to ensure the normal operation. An effective feedforward scheme is widely used to improve the dynamic performance of the system. The design of the LLRF system and high power integration test results with the prototype RF system are presented.展开更多
The China Spallation Neutron Source （CSNS） uses H- stripping and phase space painting metnocl co fill a large ring acceptance with a small emittance linac beam. The dependence of the painting beam on the injection b...The China Spallation Neutron Source （CSNS） uses H- stripping and phase space painting metnocl co fill a large ring acceptance with a small emittance linac beam. The dependence of the painting beam on the injection beam parameters was studied for the Rapid Cycling Synchrotron （RCS）. The simulation study was done for injection with different momentum spreads, different rms emittances of the injection beam, and different matching conditions. Then, the beam loss, 99% and rms emittances were obtained, and the optimized injection beam parameters were given. The interaction between H- beam and stripping foil was studied, and the effect of foil scattering was simulated. The stripping efficiency was calculated and the suitable thickness of stripping foil was obtained. In addition, the energy deposition on the foil and the beam loss due to the foil scattering were also studied.展开更多
Due to the large eddy currents at the ends of the quadrupole magnets for CSNS/RCS, the magnetic field properties and the heat generation are of great concern. In this paper, we take transient electromagnetic simulatio...Due to the large eddy currents at the ends of the quadrupole magnets for CSNS/RCS, the magnetic field properties and the heat generation are of great concern. In this paper, we take transient electromagnetic simulation and make use of the eddy current loss from the transient electromagnetic results to perform thermal analysis. Through analysis of the simulated results, the magnetic field dynamic properties of these magnets and a temperature rise are achieved. Finally, the accuracy of the thermal analysis is confirmed by a test of the prototype quadrupole magnet of the RCS.展开更多
The injecton pulsed bending bump magnets of Rapid Cycling Synchrotron （RCS） in China Spalla- tion Neutron Source （CSNS） consist of four horizontal bending （BH） magnets and four vertical bending （BV） magnets. T...The injecton pulsed bending bump magnets of Rapid Cycling Synchrotron （RCS） in China Spalla- tion Neutron Source （CSNS） consist of four horizontal bending （BH） magnets and four vertical bending （BV） magnets. The BH magnets are operated at a repetition rate of 25 Hz and are excited with a trapezoid rectangle waveform with about 1.6 milliseconds duration. The eddy current is induced in BH magnets and in the end plates it is expected to be large, so the heat generation is of our great concern. In this paper, the eddy current loss of the BH magnet has been investigated and calculated by using a coupling method of 3D electromagnetic and thermal analysis. The accuracy of the analysis is confirmed by testing the prototype BH magnet. The end plate temperature of the BH magnet provided with slit cuts has been decreased obviously and met the requirements.展开更多
The China Spallation Neutron Source/Rapid Cycling Synchrotron （CSNS/RCS） accelerates a high-intensity proton beam from 80 MeV to 1.6 GeV. Since the beam current and beam power is high, the beam loading is a severe p...The China Spallation Neutron Source/Rapid Cycling Synchrotron （CSNS/RCS） accelerates a high-intensity proton beam from 80 MeV to 1.6 GeV. Since the beam current and beam power is high, the beam loading is a severe problem for the stability of the circulating beam in the RCS. To study the beam loading effect in the CSNS/RCS theoretically, the RLC circuit model of the rf cavity, the method of Fast Fourier Transform and the method of Laplace transform have been employed to obtain the impedance of the rf system, the beam spectrum and the beam-induced voltage, respectively. Based on these physical models, the beam dynamics equations have been revised and a beam loading model has been constructed in the simulation code ORIENT. By using the code, the beam loading effect on the rf system of the CSNS/RCS has been investigated. Some simulation results have been obtained and conclusions have been drawn.展开更多
In a Rapid Cycling Synchrotron （RCS）, power loss due to an eddy current on the metal vacuum chamber would cause heating of the vacuum chamber. It is important to study the effect for estimating eddy current induced ...In a Rapid Cycling Synchrotron （RCS）, power loss due to an eddy current on the metal vacuum chamber would cause heating of the vacuum chamber. It is important to study the effect for estimating eddy current induced power loss and temperature growth. Analytical formulas for eddy current power loss for various types of vacuum chambers are derived for dipole and quadrupole repeetively. By using the prototype of dipole of CSNS/RCS, an experiment was done to test the analytical formula. The derived formulas were applied to calculating the eddy current power loss on some special structures of an RCS vacuum chamber.展开更多
基金supported by the National Natural Science Foundation of China(No.11375217)
文摘To the transverse beam collimation system in a rapid cycling synchrotron,an important component is the primary collimator,which improves emittance of the beam halo particles such that the particles outside the predefined trajectory can be absorbed by the secondary collimators.Given the material properties and power deposition distribution,the beam scraper of the primary collimator is a0.17 mm tungsten foil on a double face-wedged copper block of 121.5 mm x 20 mm.The heat is transferred to the outside by a φ34 mm copper rod.In this paper,for minimizing brazing thermal stress,we report our theoretical analysis and tests on brazing the tungsten and copper materials which differ greatly in size.We show that the thermal stress effect can be controlled effectively by creating stress relief grooves on the copper block and inserting a tungsten transition layer into the copper block.This innovation contributes to the successful R&D of the primary collimator.And this study may be of help for working out a brazing plan of similar structures.
基金Supported by National Natural Science Foundation of China(11475202,11405187,11205185)Youth Innovation Promotion Association of Chinese Academy of Sciences(2015009)
文摘The Robust Conjugate Direction Search（RCDS） method is used to optimize the collimation system for the Rapid Cycling Synchrotron（RCS） of the China Spallation Neutron Source（CSNS）. The parameters of secondary collimators are optimized for a better performance of the collimation system. To improve the efficiency of the optimization, the Objective Ring Beam Injection and Tracking（ORBIT） parallel module combined with MATLAB parallel computing is used, which can run multiple ORBIT instances simultaneously. This study presents a way to find an optimal parameter combination of the secondary collimators for a machine model in preparation for CSNS/RCS commissioning.
基金supported by China Spallation Neutron Source(CSNS)
文摘According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing,in which the thickness of tungsten slice is 0.17 mm.In order to get the best mechanical properties,the brazing temperature is suggested to be controlled under the recrystallization temperature of tungsten,while the recrystallization temperature is affected directly by the thickness of tungsten.Because of little research and application on the brazing of thin tungsten slice of 0.17 mm and copper,tensile tests are done to get the mechanical properties of tungsten slices which experience different brazing temperatures.In keeping the inner relationships between the mechanical properties and temperature,another experiment is done by using SEM to scan the microstructures including the size and distribution of crystals.Finally we determine the recrystallization temperature of tungsten slice of 0.17 mm,and get the best parameters of W/Cu brazing for scrapers of primary collimator in CSNS/RCS.
基金Supported by National Natural Science Foundation of China(11175194)
文摘The rapid cycling synchrotron （RCS） is part of the China Spallation Neutron Source （CSNS）. The RCS provides 1.6 GeV protons with a repetition rate of 25 Hz. The RF system in RCS is mainly composed of a ferrite loaded RF cavity, a high power tetrode amplifier, a bias supply of 3300 A and a digital low level RF （LLRF） system based on FPGA. The major challenge of the LLRF system is to solve problems caused by rapid frequency sweeping and the heavy beam loading effect. A total of eight control loops are applied to ensure the normal operation. An effective feedforward scheme is widely used to improve the dynamic performance of the system. The design of the LLRF system and high power integration test results with the prototype RF system are presented.
基金Supported by National Natural Science Foundation of China(11205185,11175020,11175193)
文摘The China Spallation Neutron Source （CSNS） uses H- stripping and phase space painting metnocl co fill a large ring acceptance with a small emittance linac beam. The dependence of the painting beam on the injection beam parameters was studied for the Rapid Cycling Synchrotron （RCS）. The simulation study was done for injection with different momentum spreads, different rms emittances of the injection beam, and different matching conditions. Then, the beam loss, 99% and rms emittances were obtained, and the optimized injection beam parameters were given. The interaction between H- beam and stripping foil was studied, and the effect of foil scattering was simulated. The stripping efficiency was calculated and the suitable thickness of stripping foil was obtained. In addition, the energy deposition on the foil and the beam loss due to the foil scattering were also studied.
文摘Due to the large eddy currents at the ends of the quadrupole magnets for CSNS/RCS, the magnetic field properties and the heat generation are of great concern. In this paper, we take transient electromagnetic simulation and make use of the eddy current loss from the transient electromagnetic results to perform thermal analysis. Through analysis of the simulated results, the magnetic field dynamic properties of these magnets and a temperature rise are achieved. Finally, the accuracy of the thermal analysis is confirmed by a test of the prototype quadrupole magnet of the RCS.
文摘The injecton pulsed bending bump magnets of Rapid Cycling Synchrotron （RCS） in China Spalla- tion Neutron Source （CSNS） consist of four horizontal bending （BH） magnets and four vertical bending （BV） magnets. The BH magnets are operated at a repetition rate of 25 Hz and are excited with a trapezoid rectangle waveform with about 1.6 milliseconds duration. The eddy current is induced in BH magnets and in the end plates it is expected to be large, so the heat generation is of our great concern. In this paper, the eddy current loss of the BH magnet has been investigated and calculated by using a coupling method of 3D electromagnetic and thermal analysis. The accuracy of the analysis is confirmed by testing the prototype BH magnet. The end plate temperature of the BH magnet provided with slit cuts has been decreased obviously and met the requirements.
基金Supported by National Natural Science Foundation of China(11175193)
文摘The China Spallation Neutron Source/Rapid Cycling Synchrotron （CSNS/RCS） accelerates a high-intensity proton beam from 80 MeV to 1.6 GeV. Since the beam current and beam power is high, the beam loading is a severe problem for the stability of the circulating beam in the RCS. To study the beam loading effect in the CSNS/RCS theoretically, the RLC circuit model of the rf cavity, the method of Fast Fourier Transform and the method of Laplace transform have been employed to obtain the impedance of the rf system, the beam spectrum and the beam-induced voltage, respectively. Based on these physical models, the beam dynamics equations have been revised and a beam loading model has been constructed in the simulation code ORIENT. By using the code, the beam loading effect on the rf system of the CSNS/RCS has been investigated. Some simulation results have been obtained and conclusions have been drawn.
文摘In a Rapid Cycling Synchrotron （RCS）, power loss due to an eddy current on the metal vacuum chamber would cause heating of the vacuum chamber. It is important to study the effect for estimating eddy current induced power loss and temperature growth. Analytical formulas for eddy current power loss for various types of vacuum chambers are derived for dipole and quadrupole repeetively. By using the prototype of dipole of CSNS/RCS, an experiment was done to test the analytical formula. The derived formulas were applied to calculating the eddy current power loss on some special structures of an RCS vacuum chamber.
