Characteristics of high-density theta pinches seeded with selected high-Z elements

Atomic processes in high-temperature plasmas are vital in controlled fusion research and in opacity calculations. A program at Los Alamos to observe radiation from a high-Z-seeded theta pinch has the goal of studying these processes. A 60-kV, 180-kJ capacitor bank, crowbarred at peak current, produced a B/sub z/ field of 90 kG at T/4 = 3.0 μs in a 25-cm-long, 8.2-cm-i.d. theta coil. The theta pinch, called Scyllar, has been operated with hydrogen, deuterium, or helium, seeded with a few percent of Ne, CO2, Fe(CO)5, or other elements. Radiation in the VUV range is observed with a 2.2-m grazing incidence vacuum spectrograph. Diagnostics have included pulsed laser holographic interferometry, time-resolved observations of He II 4686 A line profiles, and two-foil soft x-ray temperature measurements. For diagnostics development, the bank has been operated at 1/3 capacitance with a field of 45 kG at T/4 = 2.0 μs. Characteristics of the seeded plasmas are summarized