Instability heating of solid-fiber Z pinches
- Univ. of California, San Diego, CA (United States)
The Los Alamos High Density Z Pinch-II (HDZP-II) facility is used to study the dynamics of z-pinch plasmas generated from solid fibers of deuterated polyethylene CD2 with a range in radii of 3--60 μm. HDZP-II is a pulsed-power generator that delivers a current that rises to 700 kA in 100 ns through an inductive load. A multiframe circular schlieren records the evolution of the shape and size of the plasma on seven images taken at 10-ns intervals. These circular-schlieren images show very strong m=0 instability at the onset of current and a rapid radial expansion of the plasma. No higher-order instabilities are observed. An interferometer is used to infer the electron density and electron line density, giving a measure of the fraction of plasma contained within the outline of the circular-schlieren image at one time during the multiframe sequence. A three-channel x-ray crystal-reflection spectrometer provides the time-resolved, spatially-averaged electron temperature. The magnitude of the x-ray emission at these energies also gives qualitative information about the electron temperature and density at late times. A lower bound on the ion temperature is inferred from the particle pressure needed to balance the magnetic field pressure. The ion temperature rose above that of the electrons, strongly suggesting an additional heating term that puts energy directly into the ions. An ion heating term is proposed to explain the observed rapid radial expansion and elevated ion temperatures. This heating term is based on the assumption that the observed m=0 instabilities reconnect, enclosing magnetic flux which degenerates into turbulence in the plasma. A 0-D simulation is developed to investigate the relevance of different physical models to the data presented.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10125875
- Report Number(s):
- LA-12722-T; ON: DE94007055; TRN: 94:003645
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: Feb 1994
- Country of Publication:
- United States
- Language:
- English
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LINEAR Z PINCH DEVICES
TURBULENT HEATING
PLASMA INSTABILITY
INSTABILITY GROWTH RATES
IONIZATION
PLASMA DIAGNOSTICS
POLYETHYLENES
HIGH-VOLTAGE PULSE GENERATORS
INTERFEROMETERS
700350
700340
PLASMA PRODUCTION, HEATING, CURRENT DRIVE, AND INTERACTIONS
PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES