Emission characteristics and electron optical properties of the ZrO/W point cathode

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5614035

Tuggle, D W

The Zr/W point-cathode electron source is a high brightness, low-noise point source of electrons which has been used in several electron optical systems. It has the capability of forming a high-current, narrow-cone-angle focused electron beam at a relatively large working distance. In particular, it exceeds the performance of the LaB/sub 6/ thermionic cathode, its closest competitor, in systems where a sub-quarter-micron, several-nanoampere electron beam is required. In order to apply this emitter to an electron-optical system, characteristics such as angular intensity distribution, beam energy spread, beam noise, I-V curves, electron-gun transmission, and virtual source size should be known as a function of emitter radius, current density, temperature, and other variable parameters. This work covers all of the above characteristics except energy spread. Experimental data, theoretical explanations, and computer simulations are included. Due to the elevated temperature and high electric field present on the emitter surface, the emitter endform assumes a faceted shape, with the square (100 low-work-function facet on the end of the emitter. This facet has a distinct effect on the angular intensity distribution and also affects the virtual source size. The operating regime of the emitter was found to cover Schottky, extended Schottky and thermal field, with the typical 1 micron radius emitter operating mainly in the extended Schottky mode.

• Research Organization: Oregon Graduate Center, Beaverton (USA)
• OSTI ID: 5614035
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CATHODES
PERFORMANCE
ELECTRON BEAMS
ELECTRON SOURCES
POINT SOURCES
SCHOTTKY EFFECT
SHAPE
WORK FUNCTIONS
BEAMS
ELECTRODES
FUNCTIONS
LEPTON BEAMS
PARTICLE BEAMS
PARTICLE SOURCES
RADIATION SOURCES
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions