BPM测量束流纵向发射度与Twiss参数

Longitudinal Beam Parameters Measurement by Beam Position Monitors

摘要: 在C-ADS直线加速器样机中，为了描述束流相空间分布，需要精确测量束流在RFQ出口处的参数。束流横向信息已通过发射度重构测量获得，束流光学也得到了验证。采用了一种用BPM的SUM信号测量束流纵向参数的方法。在实验中，调节两台聚束器的聚束腔压并记录其下游BPM上的SUM信号。通过粒子群算法和TraceWin模拟相结合的方法，得到了考虑空间电荷效应的测量结果。测得的发射度与Toutatis中的模拟值相近。

Abstract: To characterize the phase space distribution of the beam in C-ADS demo linac, beam parameters need to be measured with high accuracy at the exit of RFQ. Transverse information of the beam has been measured via the method of emittance reconstruction and the beam optics has been verified. A method has been adopted to measure beam longitudinal parameters by the SUM-signal of beam position monitors. The bunching voltage of the two bunchers and the SUM-signals in the downstream BPMs are recorded in the experiment. By combining the PSO(Particle Swarm Optimization) method with TraceWin simulation, the results are obtained with the consideration of space charge effect. The measured emittance is quite close to the simulated one in Toutatis.