Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different g...Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different geometry have been numerically simulated the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz,β=0.06 beams then the relative electromagnetic parameters and geometric sizes have been compared.It is found that the second type,whose structural design is optimized with the conical stem and shaping drift-tube,can support the better accelerating performance.At the end of the paper,some structural deformation effects on frequency shifts and appropriate solutions have been discussed.展开更多
The taper-shaped superconducting quarter wave resonators with frequency of 80.5 MHz, β of 0.041 and 0.085 have been pre-researched. The radio frequency （RF） design of the cavities has been completed, and the struct...The taper-shaped superconducting quarter wave resonators with frequency of 80.5 MHz, β of 0.041 and 0.085 have been pre-researched. The radio frequency （RF） design of the cavities has been completed, and the structural design is also an important aspect which will be discussed in the following. The frequency shift caused by the etching effects of the surface treatment, the helium bath pressure and the Lorentz force, and the mechanical modes caused by the microphonic excitation have been anMyzed. The results show that the frequency variation from the Lorentz force is not serious and stiffening rings are explored aimed at decreasing the deformation brought by the helium pressure and microphonic excitation.展开更多
Acoustic characteristics of a thrust chamber with quarter-wave resonators are numerically studied based on the unsteady Reynolds-averaged Navier-Stokes(URANS) method. Organized pressure disturbance model and constant-...Acoustic characteristics of a thrust chamber with quarter-wave resonators are numerically studied based on the unsteady Reynolds-averaged Navier-Stokes(URANS) method. Organized pressure disturbance model and constant-volume bomb model are applied as artificial disturbances to excite pressure oscillations in the chamber. Eigenfrequencies and amplitudes of acoustic modes of the chamber are obtained by fast fourier transform(FFT) analysis, while damping characteristics are evaluated by the half-power bandwidth method. Predicted damping capacities of the chamber with and without quarter-wave resonators agree well with experimental results. Pressure oscillations can be controlled by a quarter-wave resonator mainly through reducing the amplitude of target acoustic mode, rather than increasing damping capacity of the chamber. Major damping mechanism of the resonator is cutting down pressure peak of target acoustic mode and raising up its pressure trough(CPRT);therefore the amplitude of target acoustic mode is reduced significantly. Moreover, acoustic energy can be dissipated by vortex at the orifice and by viscosity on the surface of a resonator, which increase damping capacity of the chamber slightly. Under the condition with multi-modes pressure oscillations, a resonator can still suppress pressure oscillations of target acoustic mode through CPRT.However, it may enhance pressure oscillations of other modes due to redistribution of oscillation energy among all acoustic modes.展开更多
A re-buncher with spiral arms for a heavy ion linear accelerator named as SSC-LINAC at HIRFL （the heavy ion research facility of Lanzhou） has been constructed. The re-buncher, which is used for beam longitudinal mod...A re-buncher with spiral arms for a heavy ion linear accelerator named as SSC-LINAC at HIRFL （the heavy ion research facility of Lanzhou） has been constructed. The re-buncher, which is used for beam longitudinal modulation and matching between the RFQ and DTL, is designed to be operated in continuous wave （CW） mode at the Medium-Energy Beam-Transport （MEBT） line to maintain the beam intensity and quality. Because of the longitudinal space limitation, the re-buncher has to be very compact and will be built with four gaps. We determined the key parameters of the re-buncher cavity from the simulations using Microwave Studio software, such as the resonant frequency, the quality factor Q and the shunt impedance. The detailed design of a 53.667 MHz spiral cavity and measurement results of its prototype will be presented.展开更多
Superconducting （SC） cavities currently used for the acceleration of protons at a low velocity range are based on half wave resonators. Due to the rising demand on high current, the issue of beam loading and space c...Superconducting （SC） cavities currently used for the acceleration of protons at a low velocity range are based on half wave resonators. Due to the rising demand on high current, the issue of beam loading and space charge problems has arisen. Qualities of low cost and high accelerating efficiency are required for SC cavities, which are properly fitted by using an SC quarter wave resonator （QWR）, We propose a concept of using QWRs with frequency 162.5 MHz to accelerate high current proton beams. The electromagnetic design and optimization of the prototype have been finished at Peking University. An analytical model derived by the transmission line theory is used to predict an optimal combination of the geometrical parameters, with which the calculation by Microwave Studio shows a good agreement. The thermal analysis to identify the temperature rise of the demountable bottom plate under various levels of thermal contact also has been done, and the maximum increment is less than 0.5 K even though the contact state is poor.展开更多
The superconducting （SC） cavities currently used for the acceleration of protons at a low velocity range are based on half-wave resonators. Due to the rising demand on high current, the issue of beam loading and spa...The superconducting （SC） cavities currently used for the acceleration of protons at a low velocity range are based on half-wave resonators. Due to the rising demand on high current, the issue of beam loading and space-charge problems has arisen. Qualities of low cost and high accelerating efficiency are required for SC cavities, which are properly fitted by using SC quarter-wave resonators （QWR）. We propose a concept of using QWRs with frequency 162.5 MHz to accelerate high current proton beams. The main factor limiting SC QWRs being applied to high current proton beams is vertical beam steering, which is dominantly caused by the magnetic field on axis. In this paper, we intend to analyze steering and eliminate it to verify the qualification of using QWRs to accelerate high intensity proton beams.展开更多
文摘Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different geometry have been numerically simulated the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz,β=0.06 beams then the relative electromagnetic parameters and geometric sizes have been compared.It is found that the second type,whose structural design is optimized with the conical stem and shaping drift-tube,can support the better accelerating performance.At the end of the paper,some structural deformation effects on frequency shifts and appropriate solutions have been discussed.
基金National Natural Science Foundation of China (91026001)
文摘The taper-shaped superconducting quarter wave resonators with frequency of 80.5 MHz, β of 0.041 and 0.085 have been pre-researched. The radio frequency （RF） design of the cavities has been completed, and the structural design is also an important aspect which will be discussed in the following. The frequency shift caused by the etching effects of the surface treatment, the helium bath pressure and the Lorentz force, and the mechanical modes caused by the microphonic excitation have been anMyzed. The results show that the frequency variation from the Lorentz force is not serious and stiffening rings are explored aimed at decreasing the deformation brought by the helium pressure and microphonic excitation.
基金supported by the National Natural Science Foundation of China (Grant No. 91841303)。
文摘Acoustic characteristics of a thrust chamber with quarter-wave resonators are numerically studied based on the unsteady Reynolds-averaged Navier-Stokes(URANS) method. Organized pressure disturbance model and constant-volume bomb model are applied as artificial disturbances to excite pressure oscillations in the chamber. Eigenfrequencies and amplitudes of acoustic modes of the chamber are obtained by fast fourier transform(FFT) analysis, while damping characteristics are evaluated by the half-power bandwidth method. Predicted damping capacities of the chamber with and without quarter-wave resonators agree well with experimental results. Pressure oscillations can be controlled by a quarter-wave resonator mainly through reducing the amplitude of target acoustic mode, rather than increasing damping capacity of the chamber. Major damping mechanism of the resonator is cutting down pressure peak of target acoustic mode and raising up its pressure trough(CPRT);therefore the amplitude of target acoustic mode is reduced significantly. Moreover, acoustic energy can be dissipated by vortex at the orifice and by viscosity on the surface of a resonator, which increase damping capacity of the chamber slightly. Under the condition with multi-modes pressure oscillations, a resonator can still suppress pressure oscillations of target acoustic mode through CPRT.However, it may enhance pressure oscillations of other modes due to redistribution of oscillation energy among all acoustic modes.
基金Supported by Pioneering and Interdisciplinary Research of Big Sciences (Y115210YQ0)
文摘A re-buncher with spiral arms for a heavy ion linear accelerator named as SSC-LINAC at HIRFL （the heavy ion research facility of Lanzhou） has been constructed. The re-buncher, which is used for beam longitudinal modulation and matching between the RFQ and DTL, is designed to be operated in continuous wave （CW） mode at the Medium-Energy Beam-Transport （MEBT） line to maintain the beam intensity and quality. Because of the longitudinal space limitation, the re-buncher has to be very compact and will be built with four gaps. We determined the key parameters of the re-buncher cavity from the simulations using Microwave Studio software, such as the resonant frequency, the quality factor Q and the shunt impedance. The detailed design of a 53.667 MHz spiral cavity and measurement results of its prototype will be presented.
基金Supported by Major Research Plan of National Natural Science Foundation of China (91026001)
文摘Superconducting （SC） cavities currently used for the acceleration of protons at a low velocity range are based on half wave resonators. Due to the rising demand on high current, the issue of beam loading and space charge problems has arisen. Qualities of low cost and high accelerating efficiency are required for SC cavities, which are properly fitted by using an SC quarter wave resonator （QWR）, We propose a concept of using QWRs with frequency 162.5 MHz to accelerate high current proton beams. The electromagnetic design and optimization of the prototype have been finished at Peking University. An analytical model derived by the transmission line theory is used to predict an optimal combination of the geometrical parameters, with which the calculation by Microwave Studio shows a good agreement. The thermal analysis to identify the temperature rise of the demountable bottom plate under various levels of thermal contact also has been done, and the maximum increment is less than 0.5 K even though the contact state is poor.
文摘The superconducting （SC） cavities currently used for the acceleration of protons at a low velocity range are based on half-wave resonators. Due to the rising demand on high current, the issue of beam loading and space-charge problems has arisen. Qualities of low cost and high accelerating efficiency are required for SC cavities, which are properly fitted by using SC quarter-wave resonators （QWR）. We propose a concept of using QWRs with frequency 162.5 MHz to accelerate high current proton beams. The main factor limiting SC QWRs being applied to high current proton beams is vertical beam steering, which is dominantly caused by the magnetic field on axis. In this paper, we intend to analyze steering and eliminate it to verify the qualification of using QWRs to accelerate high intensity proton beams.
