Upgraded ultrashort pulse reflectometry system on SSPX

Abstract

A multichannel ultrashort pulse reflectometry (USPR) system has been upgraded to enhance the performance of simultaneously measuring electron density profiles and fluctuations on the sustained spheromak physics experiment device (SSPX). In addition to the use of a high power frequency multiplier in the transmitter subsystem, the optimization of filter bandwidths in the receiver subsystem results in significant improvement of the dynamic range and signal-to-noise ratios of the USPR signals, thereby dramatically reducing the number of "lost" signals. Details of the upgraded USPR system are described together with USPR profile and fluctuation data.