Title: Development and diagnosis of an atmospheric pressure plasma torch for investigating magnetohydrodynamic instabilities

Abstract

The development and diagnosis of an atmospheric pressure, non-transferred, DC arc plasma torch for investigating magnetohydrodynamic experiments is presented. Utilizing a custom AC starter circuit coupled with a high power DC power supply a long, laminar plasma jet was successfully generated by adjusting voltage and current characteristics, gas flow rates, and torch geometry (nozzle diameter and length). A complete and detailed description of the design and operation conditions of our torch is presented such that our results may be reproduced. Utilizing copper, aluminum, and tungsten alloy electrode components in conjunction with an electrically isolated water cooling system allows for continuous torch operation. The 50 kV AC starter circuit is coupled with a 15 kW DC power supply via a series injection transformer as a part of the custom arc starter circuit components. Axial and tangential gas flow, with nitrogen as the working gas, is regulated to generate a stable, laminar, atmospheric plasma torch with a jet length of over 80 cm under ideal operating conditions. Here, to visualize the plasma interface in magnetohydrodynamics experiments, a technique was developed to image the cylindrical plasma jet in both the R-Z plane (axial) and R-θ plane (cross sectional) using planar-laser Mie scattering frommore » particles added to the surrounding gas. Plasma emission wavelengths are filtered out allowing scattered light from the particle laden-flow field illuminated at 532 nm by an Nd:YAG laser, to be isolated. Plasma electron temperature and degree of ionization were estimated using a technique based on the well-known Fowler–Milne spectroscopic method. Electron temperatures of up to 14 000 K and degree of ionization up to 27% at the torch exit were obtained.« less

Authors:

Allen, Roy C. ^[1]; Black, Wolfgang J. ^[1]; McFarland, Jacob A.  ^[1]

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+ Show Author Affiliations

1. Univ. of Missouri, Columbia, MO (United States)

Publication Date:

2019-02-25

Research Org.:

Univ. of Missouri, Columbia, MO (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1582424

Grant/Contract Number:  

NA0003345

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physics. D, Applied Physics

Additional Journal Information:

Journal Volume: 52; Journal Issue: 17; Journal ID: ISSN 0022-3727

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Richtmyer-Meshkov; Magnetohydrodynamics; Atmospheric Pressure Plasma; Fowler–Milne method; plasma torch; particle imaging velocimetry (PIV)