Internal magnetic field measurements on the helicity injected tokamak (HIT) using the transient internal probe (TIP)

Summary form only given, as follows. The transient internal probe (TIP) is a novel diagnostic designed to measure internal magnetic fields in hot plasmas. The diagnostic involves shooting a magneto-optic probe through the plasma at high velocities (greater than 2 km/s) using a two stage light gas gun. Local fields are obtained by illuminating the probe with an argon ion laser and measuring the amount of Faraday rotation in the laser light reflected from the moving probe. Currently, internal magnetic profile measurements are being conducted on the helicity injected tokamak (HIT). HIT is a low aspect ratio (A=1.5) tokamak designed to investigate steady state current drive using coaxial helicity injection. Operating parameters are T/sub e/=100, n/sub e//spl ap/5/spl times/10/sup 13/ cm/sup -3/ and I/sub p/=250 kA. Internal magnetic field profile data will be presented. The TIP diagnostic has a spatial resolution of 1 cm and 20 Gauss magnetic field resolution. System frequency response is 10 MHz.