Discharge and emission parameters of a plasma electron source based on a discharge in crossed E × H fields with various cathode materials

A plasma electron source (PES) based on a discharge in crossed E × H fields is developed and tested. The working gas is supplied to a quasi-closed PES discharge chamber, in which the conditions for effective ionization of the working gas in the axial magnetic field are created. The electron flow is formed by a positive-biased auxiliary electrode or the space charge from an ion source. Current-voltage and emission characteristics of the PES are obtained for various combinations of the cathode material (copper, titanium, and graphite) and the working gas (Ar and He). It is found that the discharge in the PES is stable when Cu and Ti are used as cathode materials with a working gas flow rate of 2–20 ml/min for Ar and 6–60 ml/min for He. The electron extraction efficiency for this type of PES attains unity in an Ar flow exceeding 6 ml/min for a Cu cathode insertion and for an Ar flow exceeding 8 ml/min for a Ti cathode insertion. The energy efficiency in a working gas (Ar) flow exceeding 10 ml/min is 4 mA/W for a Ti cathode and 2.56 mA/W for a Cu cathode. The low efficiency of this type of PES with He as the working gas is established. It is found that the appropriate choice of the working gas-cathode material pair ensuring higher values of the sputtering yield makes it possible to increase the PES efficiency.