Influence of ionization on sheath structure in electropositive warm plasma carrying two-temperature electrons with non-extensive distribution

Abstract

A collisional electropositive plasma having two-temperature (hot and cold) electrons with non-extensive distribution and warm ions is investigated for the sheath structure by taking into account the ionization in plasma. A modified Bohm's sheath criterion is realized in such a plasma, which shows considerable dependence on the non-extensive parameter, collisional parameter, ionization, ion temperature, and concentration and temperature of hot electrons. The corrected choice for the initial value of the electric field at the sheath edge is obtained for a given set of plasma parameters. The sheath thickness and the electric potential in the sheath show significant modification under the effect of non-extensive parameters and temperature and concentration of hot electrons. A noticeable change in the sheath characteristics is also recorded for different ionization rates, collisional parameters, and ion temperatures. A comparative study for the two-temperature electrons having non-extensive distribution with the electrons having Boltzmann distribution and single-temperature electrons having non-extensive distribution is also done in order to uncover the role of two-temperature, i.e., hot and cold electrons.

Are the oscillations found in magnetized collisional electronegative warm plasma artifact during plasma-surface interaction?

“…This result is similar to the result obtained by Dhawan et al [29] for the case of single q-non-extensive distributed electrons.…”

“…In order to avoid divergence of the numerical solution, the electric field at the sheath edge is assumed to have a finite value, say ψ ′ 0 = 0.1. The appropriate choice of the value of the electric field at the sheath edge has been explored in our previous publication [29]. Equation (24) reveals the magnitude of the positive ion density at the sheath edge.…”

Plasma sheath in the presence of warm ions

“…As a result of the absorption of super-thermal electrons by the wall, a cut-off Maxwellian VDF exists at the sheath edge. The electron density is obtained by taking the zeroth moment of the VDF (13) with critical velocity taken from (15), as…”

“…For the last several decades, plasma sheath problems have been extensively analysed using kinetic [1][2][3][4][5][6][7][8][9][10][11] and fluid [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] models. Tonks and Langmuir [1] were the first to consider the sheath in gas discharges, with cold ions and hot electrons, and solved the mystery of higher ion velocity in the sheath than the respective thermal velocity in the bulk plasma.…”

“…Recently, Dhawan and coworkers analysed the sheath formation with different conditions in warm electronegative plasmas using a fluid description. [12][13][14][15][16][17] The fluid and numerical description of supersonic ion flow at sheath entrance were discussed in Refs. [18][19][20][21], but kinetic analysis of a sheath with supersonic ion flow is very rare.…”