Investigation on property of electron beam plasma with diamond window

Abstract

Abstract The properties of Ar plasma generated by electron beam with initial energy of 45 keV passing through a 5 μm-thick diamond film window was investigated by experimental diagnostic and Monte Carlo simulation. It is found that the plasma light emission intensity enhances with increasing the electron beam current, while the plasma shape has no significant change. When the gas pressure increases, the plasma shrinks and becomes brighter, and its shape gradually changes from cone-shape to semi prolate spheroid. The electron density increases with increasing gas pressure and electron current. When the gas pressure is higher than 10 kPa, the electron density can reach the order of 1010 cm−3 at an electron current of 0.3 mA. Under high-pressure conditions, the plasma range with respect to gas pressure satisfies well a simple inverse relationship. The electron energy deposition distribution obtained by Monte Carlo simulation is consistent with the measured plasma light emission intensity distribution. Optical emission spectroscopy was used to analyze collision process in the electron beam plasma. The line intensities of the 2p 2, 2p 6 and 2p 10 levels grow relatively with increasing gas pressure, indicating that the atom-atom collisional processes are enhanced.