Influence of ambient gas pressure on laser induced metal ablation

Chivel, Yu.; Nasonov, V. I.

doi:10.1016/j.phpro.2010.08.144

Cited by 1 publication

(1 citation statement)

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“…A similar dominance of absorption coefficient over net radiation emission coefficient at elevated pressures has also been reported for hydrogen arcs burning at 20 bar gas pressure [26]. Likewise, a significant reduction of ablation in metal by a laser due to increased pressure of the surrounding gases has been reported in the literature [27]. This agrees with the optical micrographs, where less scar marks were observed at the inner surfaces of the tubes at 80 bar, compared to atmospheric pressure.…”

Section: B Tube-constricted Arcsupporting

confidence: 85%

Ultrahigh-Pressure Nitrogen Arcs Burning Inside Cylindrical Tubes

Abid

Niayesh

Støa-Aanensen

2019

IEEE Trans. Plasma Sci.

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When the pressure and temperature of a fluid exceed a critical point, the fluid enters into the supercritical region. In this region, the physical properties are believed to be in favor of a good current interruption medium. This study focuses on the arc voltage characteristics of nitrogen arcs burning inside cylindrical tubes at different filling pressures: 1 bar, 20 bar, 40 bar, and 80 bar, thus covering the supercritical region. Two different tube materials have been used in the experiments; alumina and PTFE. Arc voltages are measured for arcs burning inside tubes of 2, 4, 8, and 15 mm inner diameters. In addition, free-burning arcs have been investigated at the same filling pressures. The arc current was 150 A at 350 Hz throughout the study. The arc voltage is found to increase with decreasing inner diameter of the tube at atmospheric pressure. At higher filling pressures (i.e., 20 bar, 40 bar, 80 bar), however, such a simple relationship is not observed. The arc temperature and radius have been calculated based on the 'simple theory of free-burning arcs' and the 'two-zone ablation arc model'. The calculated arc radius decreases with increasing gas pressure. Furthermore, due to increased absorption of radiation at high filling pressures, ablation is found less significant for ultrahigh-pressure nitrogen arcs compared to atmospheric pressure arcs. This is in line with the observations from optical micrographs of the inner surfaces of the tubes exposed to arcs at different filling pressures.

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Section: B Tube-constricted Arcsupporting

confidence: 85%