Production of a large volume non-equilibrium region in an atmospheric argon arc plasma with a counter injection of cold gas from an annular anode

Abstract

In this letter, an annular anode is designed for producing arc plasmas with a large non-equilibrium region by using a counterflow cold gas through the annular anode. The coupled mass-momentum-energy exchange processes in an argon arc plasma are studied numerically and experimentally. The counter-injection of the cold argon gas from the center of the anode leads to a steep gradient of the heavy-particle temperature due to the formation of a thin stagnation layer resulting from the interaction of the high temperature plasma with the cold gas; and in particular, a large volume non-equilibrium “dark” plasma region is obtained above the anode surface. The results show that, with the enhancement of the convective heat transfer process in the plasma core region, the fraction of the non-equilibrium region to the whole arc plasma region reaches 92.2% where the heavy-particle temperature can be reduced significantly, e.g., ~ 2300 K, while simultaneously, the electron temperature and number density are remained at high levels greater than 8000 K and 2.4×1020 m-3, respectively, under the operating condition studied in this letter. This research not only deepens the understanding to the non-equilibrium synergistic transport mechanisms of arc plasmas, but also provides a method for producing a large volume non-equilibrium plasma region so as to promote various existing applications, or even creating new applications in the future.

Full text

Journal of Physics D: Applied Physics
J. Phys. D: Appl. Phys. 56 (2023) 11LT01 (8pp) https://doi.org/10.1088/1361-6463/acbc88
Letter
Production of a large volume
non-equilibrium region in an
atmospheric argon arc plasma with a
counter injection of cold gas from an
annular anode
Chuan Fang1, Zi-Ming Zhang1, Yao-Ting Wang1, Lan-Yue Luo1, Zhi-Hui Li2,3, Shi Zeng1
and He-Ping Li1,∗
1Department of Engineering Physics, Tsinghua University, Beijing 100084, People’s Republic of China
2Hypervelocity Aerodynamics Institute, China Aerodynamics Research and Development Center,
Mianyang 621000, People’s Republic of China
3National Laboratory for Computational Fluid Dynamics, Beijing 100191, People’s Republic of China
E-mail: liheping@tsinghua.edu.cn
Received 14 October 2022, revised 18 January 2023
Accepted for publication 16 February 2023
Published 23 February 2023
Abstract
In this letter, an annular anode is designed for producing arc plasmas with a large
non-equilibrium region by using a counterow cold gas through the annular anode. The coupled
mass-momentum-energy exchange processes in an argon arc plasma are studied numerically
and experimentally. The counter-injection of the cold argon gas from the center of the anode
leads to a steep gradient of the heavy-particle temperature due to the formation of a thin
stagnation layer resulting from the interaction of the high temperature plasma with the cold gas;
and in particular, a large volume non-equilibrium ‘dark’ plasma region is obtained above the
anode surface. The results show that, with the enhancement of the convective heat transfer
process in the plasma core region, the fraction of the non-equilibrium region to the whole arc
plasma region reaches 92.2% where the heavy-particle temperature can be reduced signicantly,
e.g. ∼2300 K, while simultaneously, the electron temperature and number density are remained
at high levels greater than 8000 K and 2.4 ×1020 m−3, respectively, under the operating
condition studied in this letter. This research not only deepens the understanding to the
non-equilibrium synergistic transport mechanisms of arc plasmas, but also provides a method
for producing a large volume non-equilibrium plasma region so as to promote various existing
applications, or even creating new applications in the future.
Keywords: non-equilibrium plasma, synergistic transport mechanism, arc discharge
(Some gures may appear in colour only in the online journal)
∗Author to whom any correspondence should be addressed.
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