The Influence Of Electron Reflection On Rf Hollow Cathode Discharge

The use of rf hollow cathode discharge in various aspects has been more extensively studied because of its higher density and higher ionization rate than DC hollow cathode discharge.This is due to the fact that the rf hollow cathode discharge is the discharge of both effects of electron pendulum motion and periodic radio frequency motion.In plasma discharge,the interaction between the charged particles and the electrode surface will have an impact on the discharge.For example,after the ion collides with the electrode,secondary electrons will be emitted and affect the discharge.In traditional radio frequency hollow cathode discharge,electrons can hardly move near the electrode,so the interaction between electrons and electrodes is usually ignored.However,as people reduce the size of the discharge device,the bombardment of electrons to the cathode is also possible,so that the interaction between the electrode and the electrode can no longer be neglected.Therefore,it is necessary to process the electrons of the bombarding electrode by reflecting or generating secondary electrons.That is,a certain reflection coefficient or an electron produced secondary coefficient is set as an input parameter in the discharge to describe the movement of the interaction between electrons and electrode surface.In this paper,a two-dimensional particle-in-cell/Monte-Carlo code has been developed to study the rf hollow cathode discharge in three areas.They are the impact of electron reflection on rf micro hollow cathode discharge,the contribution of electron reflection and ion gamma effect on the discharge and the electron reflection on the traditional rf hollow cathode discharge and high pressure rf hollow cathode discharge.The results are:1.In radio frequency(rf)micro hollow cathode discharge,when the pressure is 5 Torr,the discharge structure is sheath superposition,the density of charged particles depends on the reflection coefficient,particles energy and ionization rate will increase in different degrees.In particular,when the reflection coefficient is larger than 0.3,the electron reflection has a more pronounced effect on the discharge.2.When the electron reflection coefficient is taken as 0.5 or the electron secondary electron emission coefficient is taken as 0.5,the effects of electron reflection and electron gamma effect on the rf micro hollow cathode discharge are basically the same.The electron density in both cases is 6%greater than which the ion-induced secondary electron emission is taken as 0.1 and 6%less than which the ion-induced secondary electron emission is taken as 0.2.Therefore,the contribution of ion gamma effect and electron reflection to rf micro-hollow cathode discharge is related to the selection of secondary electron emission coefficient and electron reflection coefficient.3.In the traditional rf hollow cathode discharge and high-pressure rf micro-hollow cathode discharge,the discharge structure are sheath-plasma-sheath.The former has a large discharge space,and there will be a lot of collisions between the electrons and the background gas when the electrons move to the cathode,so almost no electrons can move to the cathode.The latter has a larger particle density,higher collision rate and lower electron energy so it is difficult for electrons to move to the cathode.Therefore,in both cases the electron reflection has little effect on the discharge.