Comprehensive Diagnostic Set For Intense Lithium Ion Hohlraum Experiments On Pbfa II

Abstract

Development of Transient Internal Probe (TIP) Magnetic Field Diagnostic. J.P. Galambos, MA. Bohnet, T.R. Jarboe, A.T. Mattick, t h d j $ %&+ The Transient Internal Probe (TIP) is designed to permit measurement of internal magnetic fields in hot, high density plasmas. The concept consists of accelerating a probe to high velocities (2.2 Km/s) in order to minimize probe exposure time to plasma. Faraday rotation within the probe is used to measure the local magnetic field. An Argon laser illuminates the probe consisting of a Faraday-rotator material with a retro-reflector that r e m s the incident light to the detection system. Performance results of the light gas gun and optical detection system will shown. To date, the gas gun has been extensively tested consistently achieving velocities between 2 and 3 Ms. The probe and detection scheme have been tested by dropping the probe through a static magnetic field. Magnetic field resolution of 20 gauss and spatial resolution of 5 mm has been achieved. System frequency response is 10Mhz. Work is currently being conducted to integrate the diagnostic system with laboratory plasma experiments. Specifically a gas interfaced system has been developed to prevent helium muzzle gas from entering the plasma chamber with the probe. Additionally the probe must be separated from the sabot which protects the probe during acceleration in the gas gun. Data will be presented showing the results of various separation techniques. Results of pressure measurements illustrating the effectiveness of the gas interface system will also be presented. The diagnostic is scheduled to make measurements on the Helicity Injected Toms (HIT) at the University of Washington. 4P29