Instability enhanced thermalization of bi-Maxwellian EEDF in multi-dipole confined hot cathode discharge: an experimental observation

• Published in: Journal of physics. D, Applied physics Applied physics, 2024-03, Vol.57 (9), p.95202
• Main Authors: Jiang, Di, Yip, Chi-Shung, Jin, Chen-Yao, Zhang, Wei, Wang, Liang, Xu, Guo-Sheng
• Format: Article
• Language: English
• Subjects: EEDF; hot cathode discharges; instability enhanced thermalization; Langmuir probes
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/1361-6463/ad0ef5

In multi-dipole confined hot cathode discharges, the presence of up to three distinct electron species has been observed by performing linear fitting of the Langmuir probe I – V traces. Nevertheless, the fundamental mechanism underlying the generation of hot electrons remains ambiguous. This work presents experimental observations to comprehensively investigate the impact of the instability-enhanced thermalization effect on the thermal equilibrium of both hot and cold electrons. Temperature composition of the electron energy distribution function (EEDF) was measured via a Langmuir probe, while instabilities was measured using a spectrum analyzer. The experimental results confirm the existence of a transition from a three-temperature Maxwellian EEDF composition to a two-temperature Maxwellian EEDF composition as the population of high-energy electrons increases. Furthermore, the process of thermalization between hot and cold electrons is found to be correlated to the effect of instability-enhanced collisions. The intensity of collisional instability also decreases with increased neutral collisionality.