Influence of Insert Structure on Hollow Cathode Discharge Characteristics

A new structure of lanthanum hexaboride (LaB₆) hollow cathode insert, which has a cylindrical core, is studied in this paper. The cylindrical core is inserted into and connected at the back of the traditional hollow cylinder part. Two inserts with core and one traditional insert are tested. The new structure can largely reduce the cathode temperature, the gas flow rate of discharge mode transition, and the discharge voltage. The insert, the core of which is closer to the orifice, has the best performance. Larger electron emission area and poor heat dissipation of the core with unchanged external heat dissipation area should be the reason. The core closer to the orifice receives more power deposition and thus results in better cathode performance. Lower temperature and extra material can extend the insert life. Overall, the new insert structure with core is better than the traditional structure.