Pulsed power diagnostics on the PLADIS I plasma gun

Abstract

Tokamak disruption simulation experiments are being conducted at the University of New Mexico (USA) using the PLADIS I plasma gun system. PLADIS I is a high power, high energy coaxial plasma gun configured to produce an intense plasma beam. The inductance and capacitance of the PLADIS I gun circuit are adjusted to produce a current pulse with a full width half max (FWHM) time of 100 /spl mu/s. Candidate materials are placed in the beam path to determine their response under disruption relevant energy densities. Various diagnostics have been used to determine the characteristics of the incident plasma and the vapor shielding plasma. Calorimeter arrays provided by the Japan Atomic Energy Research Institute were used to determine the profile of energy density deposited in the array material. A fast, two color optical pyrometer was used to determine the surface temperature of the sample as a function of time during initial plasma/surface interaction, before the vapor shield plasma becomes optically thick and obscures the surface. A time resolved target surface pressure diagnostic using a commercially available, fast response polyvinylidine fluoride pressure sensor has been built and is used to determine the pressure pulse of the plasma as a function of position and time. Data from this diagnostic regarding plasma beam spot size and pulse width are compared to results from other diagnostics. Initial results from the pressure diagnostic agree very well with the risetime of the surface temperature and the FWHM time of the gun current pulse. Further results regarding total absorbed energy, time resolved target surface temperature and time resolved target surface pressure in PLADIS I as a function of incident power and energy are presented.