Systematic trends in x-ray emission characteristics of variable-wire-number, fixed-mass, aluminum-array, Z-pinch implosions

Abstract

Increasing the number of wires an order of magnitude from 10 to almost 200 while simultaneously fixing the total wire mass in annular aluminum-wire-array Z-pinch implosions on the 20 TW Saturn generator [Proceedings of the 6th International IEEE Pulsed Power Conference (Institute of Electrical and Electronics Engineers, Piscataway, NJ, 1987), p. 310] demonstrates two separate power-law trends in the measured x-ray characteristics as a function of the initial interwire gap (g). These trends are approximately independent of the array radius. When g decreases from ∼6 to 0.4 mm, the peak total radiated power increases by a factor of 20 and the total energy by a factor of 2. There is a more rapid increase in peak power and energy radiated as g decreases for gaps greater than ∼2 mm. This increase is related to a measured decrease in precursor plasma and to a calculated decreased sensitivity of the implosion to azimuthal asymmetries that occurs when individual wire plasmas begin to merge following their vaporization. The substantial increase in power arises from an inferred increase in plasma compression and can be correlated with an almost linear reduction in the calculated effective thickness of the plasma annulus near stagnation as g decreases.