An experimental study of the dynamics of x-pinch and z-pinch plasmas
X-pinch experiments have been carried out using 12 to 100 {mu}m diameter Al wires with peak currents of 330 to 380 kA. Two wires were placed between the output electrodes of a low inductance pulser so as to cross and touch at a single point, resulting in intense K-shell soft x-ray radiation from a sub-millimeter high temperature (300 to 700 eV) and density (2 x 10{sup 19} to 1 x 10 {sup 21} cm{sup {minus}3}) plasma at the cross point. Single wire z-pinch experiments were conducted for comparison. Additional x-pinch experiments were carried out using up to eight wires at peak currents from 280 kA to 1.0 MA. Intense soft x-ray emission from the cross region occurs in short bursts. Filtered GaAs:Cr photoconducting diodes and streaked x-ray pinhole images show individual bursts lasting {le} 1 ns. Time-integrated K-shell spectra obtained with a curved KAP crystal spectrograph were used to determine the electron temperature and density for individual bright spots. A sub-ns pulsed nitrogen laser was used for time-resolved schlieren and interferometry measurements of the unstable expansion of a coronal plasma that develops around the wires. The implosion and re-expansion of the corona at the x-pinch cross region was observed immediately prior to x-ray emission. Jets of plasma were ejected along the axis, as recorded in schlieren images and visible light frame images. Late in the pulse, gaps formed along the axis with electron density {le}5 {times} 10{sup 17} cm{sup {minus}3}. Spectra indicated the presence of electron beams carrying the current in these gaps. Interferometry measurements provided the electron density profile late in the current pulse. Individual bursts of x-ray emission from one x-pinch were used to record a shadow of the dense core plasma at the initial wire position of a parallel x-pinch or z-pinch. This core expanded uniformily within the corona, surviving until it was disrupted by the implosion of the corona prior to soft x-ray emission.
- Research Organization:
- Cornell Univ., Ithaca, NY (United States)
- OSTI ID:
- 136316
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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