Effect of two-temperature electrons distribution on an electrostatic plasma sheath

Abstract

A magnetized collisionless plasma sheath containing two-temperature electrons is studied using a one-dimensional model in which the low-temperature electrons are described by Maxwellian distribution (MD) and high-temperature electrons are described by truncated Maxwellian distribution (TMD). Based on the ion wave approach, a modified sheath criterion including effect of TMD caused by high-temperature electrons energy above the sheath potential energy is established theoretically. The model is also used to investigate numerically the sheath structure and energy flux to the wall for plasmas parameters of an open divertor tokamak-like. Our results show that the profiles of the sheath potential, two-temperature electrons and ions densities, high-temperature electrons and ions velocities as well as the energy flux to the wall depend on the high-temperature electrons concentration, temperature, and velocity distribution function associated with sheath potential. In addition, the results obtained in the high-temperature electrons with TMD as well as with MD sheaths are compared for the different sheath potential.

Effect of two temperature electrons in a collisional magnetized plasma sheath

“…Electrons with v > v ch will get absorbed at the wall. Following the concept of cut off speed [17,21], the hot electron density distribution is given by…”

Ion energy distribution in a radio frequency sheath of plasma with Kappa electron velocity distribution

“…Thus, the IEDs can be expressed by. [5,9] f (E i0 ) = dN(E i0 )∕dE i0 (11) In our calculation, Equations (1) and (5)-(6) are solved through a second-order finite-difference scheme in space and an explicit scheme in time. With the plasma-sheath edge conditions n i,0 = n e,0 , (d s , t) = 0, and v i0 = C s , a set of closed non-linear equations for the sheath model and equivalent circuit model can be solved numerically by using an iteration method.…”

“…The presence of energetic electrons makes the electron distribution non-equilibrium and some deviation from the Maxwellian. Related to the problem of the sheath formation in non-stationary plasmas, some authors attempted to include the effects of a non-Maxwellian distribution function by the sum of two distributions consisting of a thermal Maxwellian background F I G U R E 1 The geometry of the radio frequency (RF) sheath model and the corresponding schematic diagram of the equivalent circuit for the RF sheath model and a small super-thermal population, [10][11][12] a q-non-extensive electron distribution, or Kappa distribution. [13][14][15][16] For plasmas described by a Kappa distribution, it has been shown [14] that the Debye length is always smaller than the shielding distance in a Maxwellian plasma.…”

Numerical study of an electrostatic plasma sheath with non‐thermal electrons and charged nanoparticles

“…[4][5][6][7][8] Since the forces acting on the dust particles and charging processes are important in characterization of the plasma sheath, numerous research studies investigated these effects and it was found that the presence of dust nanoparticles modifies the structure of the plasma sheath. [28][29][30] In this work, we use the Cairns et al [15] distribution for non-thermal electrons and investigate the effects of non-thermal electrons on the sheath structure. [15][16][17][18][19][20] At low-pressure discharges, the electron energy distribution departs significantly from the Maxwellian distribution and represents a non-thermal distribution.…”

“…Some other authors assumed two temperature electron distributions to study the effects of non-thermal electrons. [28][29][30] In this work, we use the Cairns et al [15] distribution for non-thermal electrons and investigate the effects of non-thermal electrons on the sheath structure. In recent years, this type of distribution function has been employed to investigate some basic physical characteristics of the plasmas such as dust acoustic waves, [31][32][33][34] ion acoustic waves, [35] magnetized electron-positron-ion plasma, [36] laser-created plasma, [37] electron acoustic solitary waves, [38] and dust charging.…”