Preprint Article Version 1 This version is not peer-reviewed

Plasma Expansion Dynamics in Ultra-High-Pure Hydrogen Gas

Version 1 : Received: 13 July 2018 / Approved: 13 July 2018 / Online: 13 July 2018 (10:16:46 CEST)

How to cite: Gautam, G.; Parigger, C.G. Plasma Expansion Dynamics in Ultra-High-Pure Hydrogen Gas. Preprints 2018, 2018070229 (doi: 10.20944/preprints201807.0229.v1). Gautam, G.; Parigger, C.G. Plasma Expansion Dynamics in Ultra-High-Pure Hydrogen Gas. Preprints 2018, 2018070229 (doi: 10.20944/preprints201807.0229.v1).

Abstract

Micro-plasma is generated in ultra-high-pure hydrogen gas filled inside a cell at a pressure of (1.08 ± 0.033) × 105 Pa (810 ± 25 Torr) by using a Q-switched Nd:YAG laser device operated at 1064 nm wavelength and 14 ns pulse duration. Micro-plasma emission spectra of the hydrogen Balmer alpha line, Hα, are recorded with a Czerny-Turner type spectrometer and an intensified charge-coupled device. The spectra are calibrated for wavelength and corrected for detector sensitivity. During the first few tens of nanoseconds after initiating optical breakdown, significantly Stark-broadened and Stark-shifted Hα lines mark the well-above hypersonic outward expansion. The vertical diameters of the spectrally resolved plasma images are measured for time delays of 10 ns to 35 ns to determine expansion speeds of the order of 100 km/s to 10 km/s. For time delays of the order of 0.5 µs to 1 µs, the expansion decreases to the speed of sound of 1.3 km/s in the near ambient temperature and pressure hydrogen gas.

Subject Areas

laser-plasma interactions; plasma dynamics and flow; hypersonic flows; emission spectra

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