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

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-ar ray Z-pinch implosions on the 20 TW Saturn generator [Proceedings of the 6t h International IEEE Pulsed Power Conference (Institute of Electrical and E lectronics Engineers, Piscataway, NJ, 1987), p. 310] demonstrates two separ ate 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 similar to 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 radia ted 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 sensi tivity of the implosion to azimuthal asymmetries that occurs when individua l wire plasmas begin to merge following their vaporization. The substantial increase in power arises from an inferred increase in plasma compression a nd can be correlated with an almost linear reduction in the calculated effe ctive thickness of the plasma annulus near stagnation as g decreases. (C) 1 999 American Institute of Physics. [S1070-664X(99)00404-8].