Spectroscopic characterization and imaging of laser- and unipolar arc-induced plasmas

Abstract

Characteristics of plasma properties in an ablative pulsed plasma thruster Phys. Plasmas 20, 033503 (2013) Tungsten plasmas induced by unipolar arcs were investigated using optical emission spectroscopy and imaging, and compared with laser-induced tungsten plasmas. The unipolar arcs were initiated in the linear-plasma simulator PISCES-A at UCSD under fusion relevant conditions. The electron temperature and density of the unipolar arc plasmas were in the range 0.5-0.7 eV and 0.7-2.0 Â 10 20 m À3, respectively, and increased with increasing negative bias voltage, but did not correlate with the surface temperature. In comparison, the electron temperature and density of the laser-induced plasmas were in the range 0.6-1.4 eV and 7 Â 10

Arc spot grouping: An entanglement of arc spot cells

“…From recent spectroscopic measurement results, the density and temperature of unipolar arc spot initiated on tungsten are likely to be approximately 10 20 and 0.5-0.7 eV, respectively. 22 To trigger the arcing, a pulsed laser irradiated the sample, while the sample was negatively biased by an electric power supply. Although it is possible to trigger arcing even when the target is at the floating potential (the case corresponds to unipolar arcing), the target was negatively biased from external to make it easier to trigger arcing in this study.…”

Self-Regulated Plasma Heat Flux Mitigation Due to Liquid Sn Vapor Shielding

“…The PLTE requirement is regarded to be fulfilled when this fit yields a straight line [22]. The inverse slope of the fit then yields T e [23]. For a given plasma discharge, T e was determined from averaging multiple spectra during the phase of constant B field in the discharge.…”

Growth origin of large-scale fiberform nanostructures in He-W co-deposition environment

“…The necessary condition for fuzz growth could be satisfied around the strike point in the ITER divertor 7 . There are concerns about fuzz formation in fusion reactors, which leads to the significantly reduced thermal resistance 8 and increased field electron emission [9][10][11] , may lead to the initiation of arcing and the release of large amounts of W 5,[12][13][14] .…”