Progress in current scaling and optimization of argon K-shell radiation in a Z-pinch

Summary form only given, as follows. In Z-pinch implosions, simple dynamic arguments show that for fixed initial radius of mass and fixed implosion time, imploded mass varies as I/sup 2/ and yield should scale as I/sup 4/ (inefficient regime). As the radiated yield becomes comparable to the available implosion energy, energy conservation limits the yield. Then yield is expected to increase as the mass or as 1/sup 2/ (efficient regime). We present observations of a series of argon gas-puff Z-pinch experiments to test this simple scaling model from 3 to >15 MA. We begin with recent results of an argon Z-pinch experiment with >15 MA in >110 ns on the "Z" generator. Starting from a diameter of over 8-cm, a double-shell Z-pinch implodes to <5-mm K-shell emission diameter. With a load mass of 0.8 mg/cm, K-shell X-ray output reached 260 kJ in a 16 TW peak power, 12 ns FWHM pulse. This record-high yield is consistent with the current-squared scaling predicted for the "efficient" emission regime. In addition, for the first time, efficient argon K-shell emission was produced with a large-diameter load. We then review and compare results of past experiments on a variety of generators ranging from 3 to 7 MA. Note that the peak yield varies from the expected I/sup 4/ from 2 to 4 MA to I/sup 2/ dependence from 7 to 15 MA.. Finally, we review results of optimization experiments with gas puff pinch length and alternative gas puff design on Double EAGLE. Two different techniques - laser interferometry and laser induced fluorescence - of mapping the gas distribution from the nozzle are discussed. Results of a novel spectroscopic technique using a X-ray streaking spectrograph with doping and tracer elements to trace the source of K-shell radiation are also illustrated.