Modified Bohm’s criterion in a collisional electronegative plasma having two-temperature non-extensive electrons
محورهای موضوعی : Journal of Theoretical and Applied Physics
Rajat Dhawan
1
(Plasma Science and Technology Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.|Department of Physics, MM Engineering College, Maharishi Markandeshwar, Mullana-Ambala, Haryana, India.)
Mayand Malik
2
(School of Engineering, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India.)
Hitendra K. Malik
3
(Plasma Science and Technology Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.)
کلید واژه: Two-temperature electrons, Non-extensive distribution, Ionization rate, Ion source term, Modified Bohm’ s criterion,
چکیده مقاله :
Plasma-material interaction has been a subject of interest for the past several decades due to its importance in various fields of research such as film deposition, surface nitriding, plasma etching, plasma reactors at low-pressure conditions etc. During this interaction, the presence of negative ions further plays a vital role to ease defect-free analysis of soft substrates. The response of plasma through the sheath formation, when a metallic plate or probe is inserted into it, depends on the plasma characteristics / parameters and the bias voltage used on the plate or probe. The Bohm’s criterion decides such kind of interaction. The present work theoretically demonstrates a modified Bohm’s criterion in an electronegative plasma which is collisional and has two-temperature non-extensive electrons (hot and cold electrons). The behaviour of positive ions is considered through their fluid equations, whereas the negative ions are taken to follow Boltzmann distribution. While writing the basic equations, ion source term and ionization rate are retained and Sagdeev’s potential approach is employed to evaluate the Bohm’s criterion which reveals a band for the positive ion velocity, means maximum and minimum values for the ion velocity. This modified Bohm’s criterion is studied under the effects of various plasma parameters.
