LONG-LIFE COLD CATHODE STUDIES FOR CROSSED-FIELD TUBES.
Abstract
Secondary emission ratio (delta) as a function of primary energy was measured for several compositions of Ba-Ca-Al2O3-impregnated tungsten cathodes, several compositions of Ni cermet cathodes, type 2b semiconducting diamond, and 1000 A Mo-Al2O3 films on a Mo substrate in its dependence on substrate temp. during deposition, proportion of Mo in the film, and post-deposition heat treatment temp. The maximum delta for these 4 candidates were 4.4, 6.4, 2.4 and 4.5 respectively. The substrate temp during deposition was the most significant. Delta max varied from 3.5 to 1.8 as the deposition temp. was changed from 600 to 1100 C in 100 C steps. Observations of secondary emission life in the electron bombardment test vehicle are reported for 1000A and 100A Mo-Al2O3 films under dc bombardment conditions of 1 a/sqcm at 1.2 kv. The 1000A film persisted without deterioration for more than 20 hours. The ion bombardment test vehicle for evaluating sputtering erosion of candidate materials has been operated successfully. Mo-Al2O3 film resistivities in the range 1000 - 1,000,000 ohm-cm and dielectric constants in the range 10-500 were observed. Crossed-field amplifier evaluation of a polished Pt cathode, an aloxite-roughened Pt cathode, and a 1000A Mo-Al2O3 film cathode were made.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1966
- Accession Number
- AD0487146
Entities
People
- C. R. Mcgeoch
- Debabrata Das
- L. Lesensky
Organizations
- RTX