Ingot niobium as candidate electrode material for Jefferson Lab 200 kV inverted electron photogun
- Christopher Newport University, Newport News VA (United States)
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)
This contribution describes the field emission characterization of niobium electrodes using a DC high voltage field emission test apparatus. A total of six electrodes were evaluated: two large-grain, two single-crystal, and two fine-grain that were chemically polished using a buffered-chemical acid solution. Field emission from niobium electrodes could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode is biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (<10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18.7 MV/m. Motivated by these results, an inverted electron photogun operated at Jefferson Lab injector test facility was equipped with a large-grain niobium cathode electrode and it has been successfully conditioned to 225 kV without field emission. This photogun was used to study strained superlattice GaAs and K{sub 2}CsSb photocathodes at high beam currents.
- OSTI ID:
- 22492695
- Journal Information:
- AIP Conference Proceedings, Vol. 1687, Issue 1; Conference: Ingot niobium summary workshop, Newport News, VA (United States), 4 Dec 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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