A method to monitor the length of a particle bunch, based on the combination of a Radio Frequency Deflector (RFD) with magnetic focusing elements, is presented. With respect to state-of-the-art bunch length measurement, the additional focusing element allows to measure also the correlations between the longitudinal and transverse planes in terms of both position and divergence. Furthermore, the quadrupole-based focusing increases the input dynamic range of the measurement system (i.e. allows for a larger range of beam Twiss parameters at the entrance of the RFD). Thus, measurement resolution and precision are enhanced, by simultaneously preserving the accuracy. In this paper, the method is first introduced analytically, and then validated in simulation, by the reference tool ELEctron Generation ANd Tracking, ELEGANT. Finally, a preliminary experimental validation at CLEAR (CERN Linear Electron Accelerator for Research) is reported.

提出了一种基于射频偏转器 (RFD) 与磁聚焦元件相结合的粒子束长度监测方法。对于最先进的束长度测量，附加的聚焦元件还可以测量纵向和横向平面之间在位置和发散方面的相关性。此外，基于四极的聚焦增加了测量系统的输入动态范围（即允许RFD入口处的光束Twiss参数范围更大）。因此，通过同时保持精度，测量分辨率和精度得到提高。在本文中，首先对该方法进行了分析介绍，然后通过参考工具 ELEctron Generation AND Tracking ELEGANT 进行了仿真验证。最后，报告了 CLEAR（CERN 研究用线性电子加速器）的初步实验验证。