Bunch Length Measurements at the JLab FEL Using Coherent Transition and Synchrotron Radiation
Bunch Length Measurements at the JLab FEL Using Coherent Transition and Synchrotron Radiation
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使用相干跃迁和同步加速器辐射在 JLab FEL 中测量束长度
DOI：
10.1063/1.2401405
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Gwyn P. Williams
中科院分区：
文献类型：
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作者：
P. Evtushenko;J. Coleman;K. Jordan;J. Klopf;G. Neil;Gwyn P. Williams
JLab的FEL通常使用亚皮秒束进行操作。短束长对于自由电子激光器的高增益是非常重要的。相干跃迁辐射用于束长测量已有多年的历史。这种诊断只能在脉冲光束模式下使用。我们的目标是在连续波束和74.85 MHz微脉冲重复率下运行FEL，其中135 pC的标称束电荷对应于波束的平均电流为10 mA，因此非常希望能够在任何微脉冲频率下运行连续波束时进行束长测量。我们使用傅里叶变换红外（FTIR）干涉仪，本质上是一个迈克尔逊干涉仪，来测量在FEL摆动器上游磁束压缩器的最后一个偶极子产生的相干同步辐射的频谱。这种无创诊断方法可以测量任意微脉冲频率下连续波束的束长。我们还将测量结果与…
The JLab FEL is routinely operated with sub‐picosecond bunches. The short bunch length is important for high gain of the FEL. Coherent transition radiation has been used for the bunch length measurements for many years. This diagnostic can be used only in the pulsed beam mode. It is our goal to run the FEL with CW beam and a 74.85 MHz micropulse repetition rate, which, with the 135 pC nominal bunch charge corresponds to the beam average current of 10 mA, Hence it is very desirable to have the possibility of making bunch length measurements when running CW beam with any micropulse frequency. We use a Fourier transform infrared (FTIR) interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent synchrotron radiation generated in the last dipole of the magnetic bunch compressor upstream of the FEL wiggler. This noninvasive diagnostic provides bunch length measurements for CW beam operation at any micropulse frequency. We also compare the measurements made with the ...