An instrument to synchronize Thomson scattering measurements with magnetohydrodynamic activity

摘要

We describe an instrument that synchronizes the firing of a ruby laser for a Thomson scattering diagnostic with audio‐frequency plasma oscillations. The instrument uses analog signal processing circuits to separate signal components, remove unwanted components, and produce zero‐phase synchronization pulses. A digitally controlled, self‐adjusting bandpass filter is used for sine wave processing. Additional circuitry produces pulses at the desired phase of the signal and calculates the time to start the laser‐firing sequence in advance of the desired phase. A CAMAC‐controlled data‐acquisition system is incorporated to monitor the synchronization process and to ensure that the laser is fired on the correct phase.