DC emitting characteristics of a single crystal LaB6 thermionic cathode

Author

Wang Han-bin ; Li Ming ; Liu Xi-san

Author_Institution

Inst. of Appl. Electron., CAEP, Mianyang, China

fYear

2008

fDate

6-11 July 2008

Firstpage

1

Lastpage

4

Abstract

A diode-type electron gun is used to investigate the DC emitting characteristics of a single crystal LaB₆ thermionic cathode. The emitting area is a planar 2-mm-diameter, achieving transmitted currents up to 175 mA and the current density 5.57A/cm². Comparing the measured current with Longo equation, which is accurate and applicable in the regime of practical operation. The circumstance has an effect on the emitting ability of cathode, when the vacuum is more than 7×10^-4 Pa, and the current density apparently becomes lower. Aggradation and diffusion of LaB₆ to pyrolytic graphite make the resistance of the heater lower. Experimental results show that DC emitting current density is lower than pulsed emitting due to the finite diffusion velocity of atom La and the surface adsorption of remainder-gas.

Keywords

adsorption; diodes; electron guns; lanthanum compounds; thermionic cathodes; thermionic electron emission; DC emission characteristics; DC emitting current density; LaB₆; LaB₆ aggradation; LaB₆ diffusion; Longo equation; cathode emisson ability; diode type electron gun; finite diffusion velocity; pyrolytic graphite; remainder gas surface adsorption; single crystal LaB₆ thermionic cathode; size 2 mm; Clamps; Crystals; Density measurement; Geometry; Heating; Isolators; Voltage measurement;

fLanguage

English

Publisher

ieee

Conference_Titel

High Power Particle Beams (BEAMS), 2008 17th International Conference on

Conference_Location

Xian

Type

conf

Filename

6202940