Reflection and excitation of ion-acoustic waves in a multi-component plasma with negative ions

Abstract

Reflection and excitation of ion-acoustic waves by a bipolar potential structure consisting of a grid and a metallic plate have been investigated experimentally in a multi-component plasma with negative ions. Reflection is observed owing to the presence of the negative ions, even if both the grid and the plate are biased negatively with respect to the plasma potential so as to collect positive ions. Reflection coefficients and excitation efficiencies are measured as a function of the bias voltage of the electrodes. The reflection coefficient becomes larger for a negative bias of the grid, and is almost constant for a positive bias of the grid as the partial pressure of SF6 gas is increased.

Reflection of modified Korteweg–de Vries solitons in a negative ion plasma

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22] Linear ion acoustic waves were reflected from a positively biased solid metallic plate. 9 KdV solitons were reflected from a negatively biased metal plate.…”

“…Ito and Nakamura observed the reflection of linear ion acoustic waves in the bipolar potential structure, even though both the grid and the plate were biased negatively, and explained that the reflection took place because the negative ions were repelled by the structure. 21 Cooney et al investigated the reflection of rarefactive KdV solitons from a negatively biased plate and found out that the point of reflection shifted away from the plate and the shift was proportional to ͉V bias ͉ 3/4 , where V bias is the bias voltage applied to the metal plate. 22 This suggested that the reflection occurs at the edge of the Langmuir sheath.…”