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

• Published in: IEEE Conference Record - Abstracts. PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pulsed Power Conference (Cat. No.01CH37 p. 364
• Main Authors: Sze, H., Banister, J., Chantrenne, S., Failor, P.L.C.B.H., Fisher, A., Levine, J.S., Song, Y., Waisman, E.M., Apruzese, J.P., Davis, J., Mosher, D., Thornhill, J.W., Velikovich, A.L., Weber, B.V., Coverdale, C.A., Deeney, C., Gilliland, T., Mcgurn, J., Spielman, R., Struve, K., Stygar, W., Bell, D.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2001
• Subjects: Argon; Design optimization; Doping; Energy conservation; Fluorescence; Gas lasers; Interferometry; Spectroscopy; Testing; X-ray lasers
• ISBN: 9780780371415; 0780371410
• DOI: 10.1109/PPPS.2001.961069

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.