Formation and evolution of striation plasma in high-pressure argon glow discharge

Abstract

The self-organized striation phenomenon in the positive column region of glow discharge plasma is a basic problem in gas discharge physics, which involves rich physics such as electron dynamics, transport process, discharge instability and nonlinear phenomenon. It is an important topic in basic physics and practical application. In this work an argon glow discharge striation plasma at high pressure is reported. The electrical, optical and ionization wave propagation characteristics of the striation plasma, and the evolution of the striation plasma with pressure and impurity gas are investigated experimentally. The generation and quenching mechanism of argon striation plasma are analyzed. The results show that the striation length is about 1.5 mm, and decreases with pressure increasing, and the velocity and frequency of the ionization wave are estimated at 1.87 m/s and 1.25 kHz, respectively. The measurement of optical emission spectrum shows that the generation of striation plasma is probably related to the argon metastable atoms. The stepwise ionization process caused by metastable atoms triggers off an ionization instability. The instability propagates in the form of ionization wave, which leads the plasma parameters to be modulated longitudinally, thus, forming an alternating bright and dark striation plasma. The adding of nitrogen can effectively quench metastable argon atoms and change the electron energy distribution function, which destroys the instability conditions of the plasma, therefore, the striation plasma disappears. This work provides a new insight into the understanding of the formation and annihilation mechanism of glow discharge striation plasma at high pressure.