FIRST RESULTS FROM THE SMALL TIGHT ASPECT RATIO TOKAMAK MULTIFREQUENCY PULSE RADAR REFLECTOMETER

A multifrequency pulse radar reflectometer (PRR) has been designed, co mmissioned, and is operating successfully on the small tight aspect ra tio tokamak (START). The data obtained with this technique allow the s tudy of the density profile evolution during the shot, revealing aspec ts of the plasma behavior during such events as the internal reconnect ion. A simple and effective profile-reconstruction algorithm using the stepwise profile approximation permits the monitoring of the plasma d ensity profile immediately after each shot. Cross checks between the S TART hydrogen cyanide (HCN) interferometer and the line integral densi ty determined by integrating the PRR generated data shows good agreeme nt. (C) 1997 American Institute of Physics.