Measurement and Timing-Control Techniques of Femtosecond Electron Pulse.

Updated techniques and results on the measurement and timing-control of femtosecond electron pulses are presented. Radiation emitted by an electron pulse was measured by a femtosecond streak camera, a Michelson interferometer, a 10-channel polychromator and a fluctuation method in order to estimate a longitudinal pulse shape of the electron pulse. Measurements by the streak camera, the interferometer and the polychromator agree with one another within the error of 20 %, while that by the fluctuation method was different. The numerical simulation explained the reason for it that the transverse emittance of the electron pulse affects the fluctuation of incoherent Cherenkov radiation. The synchronization of the electron pulse with the femtosecond laser pulse was also carried out. The timing jitter was 330 fs in rms and the hours-long drift was more than 1 ps. The suppression of the drift is under way by introducing a stable water cooler (within 0.01°C) for the accelerator tubes and RF gun, and an air-conditioner (within 2°C). [ABSTRACT FROM AUTHOR]