Timing stability and control at the E163 laser acceleration experiment

Abstract

The laser acceleration experiments conducted for the E163 project at the NLC Test Accelerator facility at SLAC have stringent requirements on the temporal properties of the electron and laser beams. A system has been implemented to measure the relative phase stability between the RF sent to the gun, the RF sent to the accelerator, and the laser used to generate the electrons. This system shows rms timing stability better than 1 psec. Temporal synchronicity between the 0.5 psec electron bunch, and the 0.5 psec laser pulse is also of great importance. Cherenkov radiation is used to measure the arrival time of the electron bunch with respect to the laser pulse, and the path length of the laser transport is adjusted to optimize temporal overlap. A linear stage mounted onto a voice coil is used to make shotby-shot fine timing adjustments to the laser path. The final verification of the desired time stability and control is demonstrated by observing the peak of the laser-electron interaction signal over the course of several minutes.

Production, Characterization, and Acceleration of Optical Microbunches

“…The 79MHz monitor helps diagnose potential timing jitter of the laser relative to the S-band RF system [48]. The laser position monitor is part of a feedback system that is located in the laser room.…”

“…The delay line is highly sensitive to thermal drifts making necessary a feedback system to maintain a good quality RF output pulse from the SLED system. There are also feedback systems on both the X-band klystron amplitude and phase [48]. Table 5.2: List of nominal beam parameters for the E-163/NLCTA beamline.…”