Density measurements in exploding wire-initiated plasmas using tungsten wires
- Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)
Calibrated density measurements have been obtained of the coronal plasmas around exploding 7.5{endash}40 {mu}m {ital W} wires carrying 15{endash}120 kA per wire for 30{endash}70 ns. X-ray radiographs of the exploding wire plasmas using 2.5{endash}10 keV photons from a Mo wire {ital X}-pinch backlighter enabled measurements of areal densities of {ital W} ranging from 2{times}10{sup 17}/cm{sup 2}, equivalent to 0.03 {mu}m of solid density {ital W}, to about 10{sup 19}/cm{sup 2}. The rapidly expanding (few mm/{mu}s) coronal plasmas surrounding the slowly expanding ({lt}1 mm/{mu}s) residual wire cores have areal densities up to about 2{times}10{sup 18}/cm{sup 2}. Single 7.5 {mu}m wires tested with 100 kA had as much as 90{percent} of the initial wire material in the coronal plasma. Coronal plasma {ital W} number densities were estimated to be up to a few times 10{sup 18}/cm{sup 3}, while core {ital W} densities as low as a few times 10{sup 20}/cm{sup 3} were observed. With linear arrays of four (eight) 7.5 {mu}m wires carrying 30 kA (15 kA)/wire, up to 35{percent} (25{percent}) of the initial {ital W} wire material was in the plasma around and between the wires at 46{endash}48 ns after the current started. Preheating the wires to drive off adsorbed gases and hydrocarbons increased the {ital W} mass in the coronal plasma and made it more uniform then when wires were not preheated. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 688011
- Journal Information:
- Physics of Plasmas, Vol. 6, Issue 11; Other Information: PBD: Nov 1999
- Country of Publication:
- United States
- Language:
- English
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