Development of a Laser Timing Controller for the High Time-Resolution Nd:YAG Thomson Scattering System in Heliotron J

Abstract

A new laser timing controller for the high time-resolution Nd:YAG Thomson scattering system with two Nd:YAG lasers has been developed to study improved confinement physics in Heliotron J. A PIC-based timing controller synchronizes the timings of laser oscillations with plasma discharges and enables the measurement of plasma profiles with a precision of <1 μs. The timing controller is used for the “soft start” of the system, which protects the optical components against initial unstable laser oscillations. The timing controller is designed to precisely control the delay time of the laser pulse from one laser to another, and to investigate the profile change of electron temperature and density within a short time span (>80 ns), which is crucial for transport physics studies including spontaneous transitions.