Gas Poisoning of 612-M and 311-XM Cathodes
Abstract
A 2 kA cathode was successfully developed for the DARHT-II injector. Since the DARHT injector cannot be baked and there may be virtual leaks, the local pressure near the cathode was not ideal even though the system pressure was in the 10(exp -8) Torr range. In a series of experiments using quarter-inch size button cathodes, we showed that gas poisoning was a significant factor in this pressure range. Furthermore we found that the 311-XM (doped with scandium and has an M coating) cathode was less affected by gas poisoning than the 612-M, corresponding to a lower effective work function. Water vapor was found to be the worst contaminant among the various gases that we have tested. With a 6.5-in. diameter 311-XM cathode, the DARHT-II injector produced >2 kA corresponding to a current density of 10 A/sq cm.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2008
- Accession Number
- ADA493322
Entities
People
- Ben Prichard
- E. Henestroza
- Frank Bieniosek
- George Miram
- Glen Westenskow
- Joe Kwan
- Matthaeus Leitner
- Ray Scarpetti
- Russell Mitchell
- Will Waldron
Organizations
- University of California, Berkeley