LaB6 Hollow Cathodes for Ion and Hall Thrusters

TLDR

Deep space missions and satellite station‑keeping demand high‑power ion and Hall thrusters that deliver high thrust and long life, requiring hollow cathodes capable of 10–100 A for over 10 years. The study develops a lanthanum hexaboride (LaB₆) hollow cathode to boost current capability and simplify handling and gas‑purity requirements for space thrusters. The cathode employs a LaB₆ insert inside an all‑graphite structure with an integral graphite keeper. Three sizes of the LaB₆ cathode have operated at up to 100 A, and despite higher operating temperatures, LaB₆ offers long life and far less sensitivity to propellant impurities and air exposure than conventional BaO dispenser cathodes.

Abstract

Deep space missions and satellite station-keeping applications continue to demand higher power ion thrusters and Hall thrusters capable of providing high thrust and longer life. Depending on the thruster size, the hollow cathodes may be required to produce discharge currents in the 10-100 A range with lifetimes in excess of 10 years. A lanthanum hexaboride (LaB 6 ) hollow cathode has been developed for space applications to increase the current capability from the cathode and ease the handling and gas purity requirements. This cathode uses a LaB 6 insert in an all-graphite hollow cathode structure with an integral graphite keeper. Three different sizes of the LaB 6 cathode have been successfully operated at discharge currents of up to 100 A to date. Although the LaB 6 cathode insert operates at a higher temperature than the conventional BaO dispenser cathode, LaB 6 offers the capability of long life and orders of magnitude less sensitivity to propellant impurities and air exposure than conventional dispenser cathodes.