The role of gas composition in plasma-dust structures in RF discharge

Abstract

The influence of a mixture of light and heavy gases, i.e., helium and argon, on plasma-dust structures in the radiofrequency discharge has been studied. The dust chains in the sheath of the radiofrequency discharge, the average distance between the dust particles and their chains, have been analyzed. A significant effect of small amounts of argon on the correlation characteristics of dust particles has been observed. The results of numerical simulation of ion and electron drift in the mixture of helium and argon are presented. It is shown that even 1% of argon admixture to helium produces such an effect that argon ions become the main components of the discharge, as they drift with lightweight helium forming a strongly anisotropic velocity distribution function. V C 2015 AIP Publishing LLC. [http://dx.

Method of Control of Ion Drag Force in Complex Plasmas

“…In the mixture at 2 % of xenon we observed the reduction of the vertical interparticle distance in comparison with the distance in pure helium for 10 %, from 0,3 mm to 0,27 mm. It agrees qualitatively with calculations of interparticle distances executed in [16] for helium mixture with heavy gases and agrees with new experiment in helium-argon mixtures [15]. Under used conditions (elevated pressure, too small particles) there is no single physical reason for control of interparticle distance.…”

“…The measured dependences of angular velocity displaying a variation of ion drag force at using of mixture of gases are well agreed with simulation model [14][15][20][21][22][23][24][25][26][27].…”

“…It is possible to conclude that the parameters of dust structures in the mixture are agreed qualitatively with calculations [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. It gives the chance to create the dust plasma with new properties (for example, with a demanded anisotropy and a density of packing in the crystal lattice of the plasma crystal) changing longitudinal interpartial distance by means of gas additive.…”

“…In [12] the nematic-type crystal is created; in [13] the interparticle distance was varied by a hydrogen additive in plasma-forming gas. An influence of argon additive in helium on packing type and on interparticle distance was investigated in [14,15]. Conditions of phase transitions at additive of krypton in helium were investigated in [16].…”

“…Systematic investigations of influence of gas composition on characteristics of collisions of ions and electrons, parameters of their drift, a charging and an interaction between dust particles are contained in series of works [14][15][16][17][20][21][22][23][24][25][26][27]. Let us note some effects important for dust plasma obtained in them.…”