Numerical Simulation And Experimental Study Of Hollow Cathode

Hollow cathode is one of the critical components of Stationary Propulsion Thruster (SPT). It can be used in two ways as follows: it supplies electron flux that is used for neutralize ion flux from channel of SPT; furthermore, it provides electrons to ionize neutral gas in the channel. Parameters and structure of hollow cathode selected have a great influence on the performance of SPT.Firstly, hollow cathode was modeled. Because the main process of hollow cathode occurs at its orifice and insert region, the model was simplified. Only hold and insert region were considered. Continuity equation, continuity equation and energy equation were developed for orifice and insert region separately. The orifice was regard as a cylinder. An electric field with only axial component was imposed. The generating and passing rate of ions were thought to be the same. Ohmic heating, ionization and continuity equation of current determined energy equation. Only at inlet and outlet of orifice the current equation was thought be satisfied. The equations for the insert region were developed like the equations developed for orifice. Only energy equation was determined by electron transport, ion transport at the orifice, ohmic heating, ions loss and electron flow of current. Then equations of electron temperature and electron density were obtained.The equations were solved by Newton iteration method. Electron temperatures and densities at different flow rates are obtained. The result showed that electron temperature decreased with an increasing flow rate of hollow cathode. But electron density increased, however.An experiment was carried on to deeply study the influence of SPT by hollow cathode. How the flow rate and heating power of cathode acted on ignition voltage and heating current was obtained. With an increased flow rate, ignition voltage increases. Electron emission increases with heating power increasing, but ignition voltage drops. With the increase of flow rate, discharge current increases, efficiency drops. With an increased cathode power, discharge current decreases, efficiency of SPT increases.