Annual Summary Report on Thermionic Cathode Project.
Abstract
A planar cathode, Pierce type electron gun with a design perveance of .0000032 (Amps/volts to the 3/2 power) has been operated with a lanthanum hexaboride (LaB6) cathode. The cathode (useful diameter 1.9 cm) is heated by bombardment by electrons from a small tungsten filament. The bombardment heating system is stabilized by a feedback control circuit. The power required to heat the cathode is 315 W bombardment power and 200 W filament power. Heating power has been reduced by careful heat shielding and reduction of heat conduction losses. Significant additional reductions should be possible. The sintered LaB6 cathode disk is 2.5 cm in diameter, 3.2 mm thick, and has a density of 94%. No problems have been encountered with cracking of the disk. Cathode emission is insensitive to repeated exposure to air after allowing the cathode to fully cool. The measured perveance and anode transmission of the gun are 3.2x10-6 and 94%, respectively. Current densities up to 6.5 A/sq cm have been reached with 5 micrometers pulses. Measurements were made at cathode temperatures of 1300 to 1600 C.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 09, 1986
- Accession Number
- ADA168569
Entities
People
- Mark E. Herniter
- Ward D. Getty
Organizations
- University of Michigan