西安200 MeV质子应用装置射频四极加速器的设计与测试

Design and Test of Radio Frequency Quadrupole Accelerator for Xi’an 200 MeV Proton Application Facility

介绍了西安200 MeV质子应用装置(XiPAF)射频四极加速器(RFQ)的物理设计、低功率冷测与调谐、高功率老练及束流调试结果。这台四翼型RFQ长度为3 m,主要功能是将电子回旋共振(ECR)离子源产生的负氢离子束流进行聚焦、聚束,并将束流能量从50 keV提高到3 MeV,然后注入到下游的漂移管直线加速器(DTL)中。这台RFQ的注入峰值电流强度设计值为6 mA,束流脉冲最大重频为0.5 Hz,脉宽为10~40μs。经过加工安装和冷测调谐,RFQ四极工作模式场分布测量值与设计值的相对偏差小于2.7%,二极模式占比小于±1.9%。RFQ高功率老练完成后,在束流调试中顺利找到工作点。在工作点下,RFQ传输效率能达到94%,出口束流横向归一化均方根(RMS)发射度为0.4πmm·mrad^(-1),束流能量为2.96 MeV。

In this paper,the physical design,low power test and tuning,high power conditioning,and beam commissioning result of the radio frequency quadrupole(RFQ)accelerator of Xi’an 200 MeV Proton Application Facility(XiPAF)are presented.The 3-meter-long RFQ will accelerate the H-beam from 50 keV to 3 MeV,and deliver it to the downstream drift tube linac(DTL).The design value of the injection peak current intensity of this RFQ is 6 mA,the maximum repetition frequency of the beam pulse is 0.5 Hz,and the pulse width is 10~40μs.After machining,assembling,and tuning,the relative deviation between the measured value and the design value of RFQ quadrupole working mode field distribution is less than 2.7%,and the proportion of two-pole mode is less than±1.9%.After the completion of RFQ high-power RF conditioning and beam commissioning,the working point can be found successfully in beam commissioning.The RFQ transmission efficiency can reach 94%at the operation point,with the transverse normalized RMS emittance of the output beam of 0.4πmm·mrad,and the beam energy of 2.96 MeV.