Dust charging and levitating in a sheath of plasma containing energetic particles

Abstract

The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited (OML) theory, the dust grain charging inside the sheath of plasma containing energetic particles is examined for the carbon wall, and then the effect of the energetic particles on the stationary dust particle inside the sheath is discussed through the trapping potential energy. It is found that with the increase of energetic ion concentration or energy, the size of dust staying in levitation equilibrium decreases and the levitating position is much closer to the wall. In the case of deuterium ions as energetic ions, the bigger dust particle can be trapped by the sheath than in the case of hydrogen ions as energetic ions. When the energetic electron component is present, the levitating position of dust particle in the sheath depends strongly on the energetic electron. The levitating dust particle is closer to the wall as the energetic electron energy or concentration is increased. In addition, with the increase of temperature of thermal background ion, the size of dust particle trapped by the sheath decreases and the levitating positions of dust particles with the same size radius inside the sheath move toward the wall. Our results can be helpful in investigating the property of the sheath where the energetic particle component is present.

Dust particle charging process in a radio frequency sheath of plasma containing kappa distribution electrons

“…2003; Ou et al. 2018; Ou & Huang 2020). Apart from the RF field frequency, the dust particle radius is usually assumed to be much smaller than the local electron Debye length.…”

“…The RF sheath of plasma containing non-Maxwellian electrons has been investigated recently (Ou, An & Men 2019;Ou & Huang 2020) and it is found that the supra-thermal electrons can modify the spatio-temporal variation of the plasma profile in the sheath region; such an effect of the non-Maxwellian electrons on the dust particle charge can be expected. According to the results of dust particles in a static sheath of non-Maxwellian plasma (Foroutan & Akhoundi 2012;Ou, Zhao & Lin 2018;El Ghani, Driouch & Chatei 2019;Khalilpour & Foroutan 2020;Zhao et al 2020), it has been shown that the non-Maxwellian electrons can modify the profile of the dust particle when the dust components are relatively dense (Foroutan & Akhoundi 2012;El Ghani et al 2019;Khalilpour & Foroutan 2020), while they can change the dust particle charging process and levitation when the dust density is very low (Ou et al 2018;Zhao et al 2020). Since the charge number of the dust particle in an RF sheath depends strongly on the RF field (Bacharis et al 2010), the dust particle charging process in the non-Maxwellian electron RF sheath is more complex than in the static sheath.…”

“…Under this condition, the ions respond only to the time-averaged electric field and the electrons follow the instantaneous RF field. To show the dust particle charge in an RF sheath with s wide range of frequency, we discuss a dust particle immersed in the sheath of a plasma obtained from a self-consistent model for the structure of the RF driven by a sinusoidal current source at the wall in the ion cyclotron range of frequency (ICRF) (Edelberg & Aydil 1999;Hou et al 2003;Ou et al 2018;Ou & Huang 2020). Apart from the RF field frequency, the dust particle radius is usually assumed to be much smaller than the local electron Debye length.…”

“…The RF sheath of plasma containing non-Maxwellian electrons has been investigated recently (Ou, An & Men 2019; Ou & Huang 2020) and it is found that the supra-thermal electrons can modify the spatio-temporal variation of the plasma profile in the sheath region; such an effect of the non-Maxwellian electrons on the dust particle charge can be expected. According to the results of dust particles in a static sheath of non-Maxwellian plasma (Foroutan & Akhoundi 2012; Ou, Zhao & Lin 2018; El Ghani, Driouch & Chatei 2019; Khalilpour & Foroutan 2020; Zhao et al. 2020), it has been shown that the non-Maxwellian electrons can modify the profile of the dust particle when the dust components are relatively dense (Foroutan & Akhoundi 2012; El Ghani et al.…”

Effects of non‐extensive electrons on the sheath of dusty plasmas with variable dust charge

“…It can be found in various technological devices, such as the device for plasma‐assisted material and plasma nanofabrication, plasma discharges, and plasma medicine, as well as controlled fusion devices . Most of the research articles discussed the effect of parameters that can modify the sheath characteristics in dusty plasmas, for example the action of an external magnetic field, the collisions force, the multi‐species of positive or/and negative ions, the two electron temperature, the dust charge variation, and the size of dust grains . In all of these investigations mentioned above, the electron distribution has been assumed to be Maxwellian (i.e., which is based on the Boltzmann‐Gibbs [BG] statistics).…”