PBFA Z: A 55 TW/4.5 MJ electrical generator

Abstract

PBFA Z is a new 55 TW/4.5 MJ short pulse electrical driver located at Sandia National Laboratories. We use PBFA Z to magnetically-implode plasma shells. These configurations are historically known as Z pinches. The pulsed power design of PBFA Z is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 4.5 MJ in 55-TW/105-ns pulse to the output water transmission lines, and delivers up to 3.0 MJ and 40 TW of electrical energy to the Z-pinch load. Depending on the initial load inductance and the implosion time, we attain peak currents of 16-20 MA with a rise time of 105 ns. Current is fed to the Z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV/cm. The current from the four independent conical disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The measured system performance of the water transmission lines, the vacuum insulator stack, the MITLs, and the double post-hole vacuum convolute differed from preshot predictions by /spl sim/5%. Using a 2-cm radius and a 2-cm length tungsten wire array with 240, 7.5-/spl mu/m diameter wires (4.1-mg mass) as the Z-pinch load, we achieved X-ray powers of 200 TW and X-ray energies of 1.85 MJ as measured by X-ray diodes and resistive bolometry.