Electron Emission Study Of The Impact Of Steady-state Plasma Sheath

Between the plasma and any surface, a sheath will form in order to balance the ion current and the electron current at the solid surface. When charged particles gain an energy above the surface work function on crossing the sheath, their impingement against the surface can cause the ejection of secondary electrons. Similarly, a thermal surface can emit thermionic electrons. These two kind of electrons are considered as emitted electrons in this paper. The existence of the emitted electrons can affect the sheath parameters, such as the sheath electric field, particle beam current density etc., as a result, it can affect the plasma technology on some degrees. So, it is very necessary to study the effect of emitted electrons on plasma sheath. A set of nonlinear self-consistent equations is settled in this paper. Firstly, We have studied the effect of emitted electrons on floating sheath. Secondly, We have studied the effect of emitted electrons on the steady- state argon plasma sheath where the secondary electron-neutral atom collisions and the ion-neutral atom collisions were taken into account. Lastly, the effects of secondary electrons on the sheaths about the diamond film deposition and diamond-like carbon(DLC) film deposition technology have been studied. Numerical results indicate: When considering the collision effects, the distributions of the sheath electric field, the sheath potential, emitted electrons kinetic energy and the ion beam current density are changed on some degree. When increases the gas density or emitted electron beam current density, the effects become obvious. Owing to the smallness of the methane cross section, the collision effect on the sheath about the DLC sheath is weak, but the existence of the emitted electrons can affect the sheath parameters.