Hydrogen negative ion source with LaB 6 inserts

• Main Authors: Belchenko, Yu. I., Kuznetsov, G. I., Grigoryev, E. A.
• Format: Conference Proceeding
• Language: English
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.1150390

The compact negative ion source having a semiplanotron discharge geometry and the two independently heated LaB 6 cathode inserts was developed and studied. The hot LaB 6 cathode insert supports discharge ignition and operation at low hydrogen pressure, while the cold one provides the glow discharge concentration in its vicinity. The stable production of H − beams with the current density in the emission hole in the range of about 0.1 A/cm2 was obtained in the pure hydrogen discharge. Negative ion yield at the different parts of the composite source cathode was measured. It was maximal in the glow region. An enhanced H − yield was recorded due to discharge concentration near the LaB 6 inserts. LaB 6 with a decreased work function does not produce a sizable income of surface-produced negative ions to the beam, extracted from the pure hydrogen discharge. The use of LaB 6 inserts as a reliable source of electrons to form the discharge simplifies the surface-plasma source use.