Control of Electron Temperature by Varying DC Voltage to a Mesh Grid Blanketed with Thin Film in Plasmas

Abstract

The basic characteristics of control of electron temperature in weakly ionized plasma have been investigated in the absence of magnetic field using a grid-bias method. To control the electron temperature, dc voltage is applied to a mesh grid covered with a thin film. Although the grid is covered with a thin film made of a diamond-like carbon known as an insulating material, the electron temperature can still be controlled from 1.0 to 0.045 eV by varying the dc voltage of the grid from 40 to -10 V at an argon gas pressure of 20 mTorr accompanied by an electron density increase in a cold-cathode discharge plasma. We also provide theoretical discussions to clarify how the resistance of the film deposited on the metal grid affects the efficiency of the control of electron temperature in the case of the grid-bias method. This technique of electron-temperature control is available for reactive plasmas in which grids are often deposited by thin films made of hydrogenated amorphous substance, diamond-like carbon and so forth.