Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ...Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.展开更多
A room temperature heavy ion linac has been proposed as a new injector of the main Cooler Storage Ring（CSRm） at the Heavy Ion Research Facility in Lanzhou（HIRFL）, which is expected to improve the performance of HI...A room temperature heavy ion linac has been proposed as a new injector of the main Cooler Storage Ring（CSRm） at the Heavy Ion Research Facility in Lanzhou（HIRFL）, which is expected to improve the performance of HIRFL. The linac injector can supply heavy ions with a maximum mass to charge ratio of 7 and an injection kinetic energy of 7.272 MeV/u for CSRm; the pulsed beam intensity is 3 emA with the duty factor of 3%. Compared with the present cyclotron injector, the Sector Focusing Cyclotron（SFC）, the beam current from linac can be improved by 10–100 times. As the pre-accelerator of the linac, the 108.48 MHz 4-rod Radio Frequency Quadrupole（RFQ） accelerates the ion beam from 4 keV/u to 300 keV/u, which achieves the transmission efficiency of 95.3% with a 3.07 m long vane.The phase advance has been taken into account in the analysis of the error tolerance, and parametric resonances have been carefully avoided by adjusting the structure parameters. Kombinierte Null Grad Struktur Interdigital H-mode Drift Tube Linacs（KONUS IH-DTLs）, which follow the RFQ, accelerate ions up to the energy of 7.272 MeV/u for CSRm. The resonance frequency is 108.48 MHz for the first two cavities and 216.96 MHz for the last 5 Drift Tube Linacs（DTLs）. The maximum accelerating gradient can reach 4.95 MV/m in a DTL section with the length of17.066 m, and the total pulsed RF power is 2.8 MW. A new strategy, for the determination of resonance frequency,RFQ vane voltage and DTL effective accelerating voltage, is described in detail. The beam dynamics design of the linac will be presented in this paper.展开更多
A hybrid single cavity （HSC） linac, which is formed by combining a radio frequency quadrupole （RFQ） and a drift tube （DT） structure into one interdigital-H （IH） cavity, is fabricated and assembled as a proof o...A hybrid single cavity （HSC） linac, which is formed by combining a radio frequency quadrupole （RFQ） and a drift tube （DT） structure into one interdigital-H （IH） cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme （DPIS）, which can inject a high intensity heavy ion beam produced by a laser ion source （LIS）. The input beam current of the HSC is designed to be 20 mAC6＋ ions. According to numerical simulations, the HSC linac can accelerate a 6-mA C6＋beam, which meets the requirement of the needed particle number for cancer therapy （10s-9 ions/pulse）. The HSC injector with the DPIS method makes the existing multi- turn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency （rf） measurements show excellent rf properties for the resonator, with a measured Q equal to 91% of the simulated value. A C6＋ ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.展开更多
文摘Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.
基金Supported by National Fund Committee Innovation Group(11221064)National Basic Research Program of China(2014CB845500)
文摘A room temperature heavy ion linac has been proposed as a new injector of the main Cooler Storage Ring（CSRm） at the Heavy Ion Research Facility in Lanzhou（HIRFL）, which is expected to improve the performance of HIRFL. The linac injector can supply heavy ions with a maximum mass to charge ratio of 7 and an injection kinetic energy of 7.272 MeV/u for CSRm; the pulsed beam intensity is 3 emA with the duty factor of 3%. Compared with the present cyclotron injector, the Sector Focusing Cyclotron（SFC）, the beam current from linac can be improved by 10–100 times. As the pre-accelerator of the linac, the 108.48 MHz 4-rod Radio Frequency Quadrupole（RFQ） accelerates the ion beam from 4 keV/u to 300 keV/u, which achieves the transmission efficiency of 95.3% with a 3.07 m long vane.The phase advance has been taken into account in the analysis of the error tolerance, and parametric resonances have been carefully avoided by adjusting the structure parameters. Kombinierte Null Grad Struktur Interdigital H-mode Drift Tube Linacs（KONUS IH-DTLs）, which follow the RFQ, accelerate ions up to the energy of 7.272 MeV/u for CSRm. The resonance frequency is 108.48 MHz for the first two cavities and 216.96 MHz for the last 5 Drift Tube Linacs（DTLs）. The maximum accelerating gradient can reach 4.95 MV/m in a DTL section with the length of17.066 m, and the total pulsed RF power is 2.8 MW. A new strategy, for the determination of resonance frequency,RFQ vane voltage and DTL effective accelerating voltage, is described in detail. The beam dynamics design of the linac will be presented in this paper.
基金Supported by National Natural Science Foundation of China and One Hundred Person Project of CAS
文摘A hybrid single cavity （HSC） linac, which is formed by combining a radio frequency quadrupole （RFQ） and a drift tube （DT） structure into one interdigital-H （IH） cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme （DPIS）, which can inject a high intensity heavy ion beam produced by a laser ion source （LIS）. The input beam current of the HSC is designed to be 20 mAC6＋ ions. According to numerical simulations, the HSC linac can accelerate a 6-mA C6＋beam, which meets the requirement of the needed particle number for cancer therapy （10s-9 ions/pulse）. The HSC injector with the DPIS method makes the existing multi- turn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency （rf） measurements show excellent rf properties for the resonator, with a measured Q equal to 91% of the simulated value. A C6＋ ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.
