Title :
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
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;
Conference_Titel :
High Power Particle Beams (BEAMS), 2008 17th International Conference on
Conference_Location :
Xian
