Title: Investigation of the short argon arc with hot anode. I. Numerical simulations of non-equilibrium effects in the near-electrode regions

Abstract

The atmospheric pressure arcs have recently found application in the production of nanoparticles. The distinguishing features of such arcs are small length and hot ablating anode characterized by intensive electron emission and radiation from its surface. We performed a one-dimensional modeling of argon arc, which shows that near-electrode effects of thermal and ionization non-equilibrium play an important role in the operation of a short arc, because the non-equilibrium regions are up to several millimeters long and are comparable to the arc length. The near-anode region is typically longer than the near-cathode region and its length depends more strongly on the current density. The model was extensively verified and validated against previous simulation results and experimental data. The Volt-Ampere characteristic (VAC) of the near-anode region depends on the anode cooling mechanism. The anode voltage is negative. In the case of strong anode cooling (water-cooled anode) when the anode is cold, temperature and plasma density gradients increase with current density, resulting in a decrease of the anode voltage (the absolute value increases). Falling VAC of the near-anode region suggests the arc constriction near the anode. Without anode cooling, the anode temperature increases significantly with the current density, leading to a drastic increasemore » in the thermionic emission current from the anode. Correspondingly, the anode voltage increases to suppress the emission, and the opposite trend in the VAC is observed. The results of simulations were found to be independent of sheath model used: collisional (fluid) or collisionless model gave the same plasma profiles for both near-anode and near-cathode regions.« less

Authors:

Khrabry, A.  ^[1];

• Search DOE PAGES for author "Khrabry, A."
• Search DOE PAGES for ORCID "0000-0002-2855-7148"

Kaganovich, I. D.  ^[1];

• Search DOE PAGES for author "Kaganovich, I. D."
• Search DOE PAGES for ORCID "0000-0003-0653-5682"

Nemchinsky, V.  ^[2];

• Search DOE PAGES for author "Nemchinsky, V."
• Search DOE PAGES for ORCID "0000-0002-6064-7354"

Khodak, A. ^[1]

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+ Show Author Affiliations

1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2. Keiser Univ., Fort Lauderdale, FL (United States)

Publication Date:

Mon Jan 22 00:00:00 EST 2018

Research Org.:

Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

1419791

Alternate Identifier(s):

OSTI ID: 1417712

Grant/Contract Number:  

AC02-09CH11466

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 25; Journal Issue: 1; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY