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Effect of insulator surface conditioning on the pinch dynamics and x-ray production of a Ne-filled dense plasma focus
- Source :
- Journal of Applied Physics. 129:223303
- Publication Year :
- 2021
- Publisher :
- AIP Publishing, 2021.
-
Abstract
- The dense plasma focus (DPF) can be an intense source of x rays, wherein the insulator sleeve strongly dictates the electrical breakdown, which subsequently affects the formation of a plasma sheath and a collapse phase. Experiments on a 25 kJ DPF (operated at 4.4 kJ) are carried out to demonstrate the influence of insulator surface morphology on the pinch structure, dynamics, and x-ray yield using a Ne fill. Two borosilicate insulators are directly compared, one with a smooth finish and the other machined with four circumferential grooves traversing the perimeter of the exterior insulator surface. Comparisons are made through same-shot imaging diagnostics of the evolving plasma sheath during breakdown, rundown, and at the pinch in addition to the time-resolved measurements of emitted x rays via filtered photodiodes. The presence of structures on the insulator sleeve reduces x-ray production across all fill pressures by a factor of 2.8 ± 2.4 on average and reduces the highest x ray producing shots by a factor of 5.5 ± 1.8. Observations of sheath asymmetry and inhomogeneity at lift-off are observed and correlated with subsequent observations of off-axis radial collapse. Taken together, this suggests that local variations in the insulator surface decrease the spatial uniformity of the sheath, leading to an azimuthally asymmetric focus, reduced electron densities, and, ultimately, degraded x-ray production.
- Subjects :
- 010302 applied physics
Debye sheath
Yield (engineering)
Materials science
Dense plasma focus
Electrical breakdown
General Physics and Astronomy
Insulator (electricity)
02 engineering and technology
Electron
021001 nanoscience & nanotechnology
01 natural sciences
Molecular physics
symbols.namesake
Phase (matter)
0103 physical sciences
Pinch
symbols
0210 nano-technology
Subjects
Details
- ISSN :
- 10897550 and 00218979
- Volume :
- 129
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Physics
- Accession number :
- edsair.doi...........ef5d8d30a3e48b1e5d419bf080782b30
- Full Text :
- https://doi.org/10.1063/5.0050203