Electrode activation in cesium-free negative ion sources

Journal Article · Mon Feb 15 00:00:00 EST 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3277164· OSTI ID:22053829

Dudnikov, Vadim; Johnson, Rolland P ^[1]

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1. Muons, Inc., Batavia, Illinois 60510 (United States)

Features of emission electrode activation leading to enhancement of negative ion emission in cesium-free discharges are discussed. In some ion sources with cesium-free discharges, the emission of negative ions has been increased significantly by emission electrode activation using strong heating of the negative biased electrode by discharge plasma. A simple explanation of this enhancement is that it is due to an accumulation on the emission surface of the plasma electrode of impurities with low ionization potential that decreases in surface work function and increases the secondary emission of negative ions similar to ''Cesiation.'' The negative biasing of emission surface is important for accumulation and trapping the impurities on the emission surface. To effectively control the activation process it is important to directly detect the evolution of the work function and the impurity concentration during electrode activation with enhancement of negative ion emission.

• OSTI ID: 22053829
• Journal Information: Review of Scientific Instruments, Vol. 81, Issue 2; Conference: ICIS 2009: 13. international conference on ion sources, Gatlinburg, TN (United States), 20-25 Sep 2009; Other Information: (c) 2010 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANIONS
CESIUM
ELECTRIC DISCHARGES
ELECTRODES
ION SOURCES
IONIZATION POTENTIAL
PLASMA HEATING
PLASMA IMPURITIES
SECONDARY EMISSION
SURFACES
WORK FUNCTIONS