Characterization of in situ work function and cesium flux measurement setup suitable for cesium seeded negative ion source applications
Abstract
A proof of principle experiment has been performed for the in situ measurement of the work function in vacuum conditions ( 10-7 torr) relevant to cesium-seeded negative ion sources for fusion applications. The work function is measured using the principle of the photoelectric effect. The performance of the work function measurement setup and temperature-controlled cesium (Cs) oven has been characterized using various diagnostics such as a quartz crystal microbalance, a surface ionization detector and pressure measurements. The background impurities responsible for work function degradation are detected using the residual gas analyzer. The work function (≤3.06 eV) and Cs flux ( 1012 atoms s-1) have been measured directly at the sample surface during controlled Cs evaporation using a novel, inexpensive and portable design of the cathode-anode assembly.
- Publication:
-
Nuclear Fusion
- Pub Date:
- October 2019
- DOI:
- 10.1088/1741-4326/ab312c
- Bibcode:
- 2019NucFu..59j6023S
- Keywords:
-
- cesium;
- work-function;
- photoelectric effect;
- cesiated-tungsten;
- negative ion source;
- fusion;
- neutral beam injector