Negative-ion-beam generation with the ORNL SITEX source

Technical Report · Sat May 01 04:00:00 EDT 1982

DOI:https://doi.org/10.2172/5325671· OSTI ID:5325671

Dagenhart, W. K.; Stirling, W. L.; Kim, J.

Parametric studies were made on a hot cathode reflex discharge H/sup -/ Surface Ionization source with Transverse Extraction (SITEX) in both the pure hydrogen and the mixed hydrogen-cesium mode. Extraction current density, beam current, gas efficiency, extracted electron-to-H/sup -/ current ratio, heavy negative ion impurities, optics, and long pulse operation were investigated as a function of time, arc voltage, arc current, converter voltage, H/sub 2/ gas flow, cesium feed rate, and plasma generator geometries. Initial results of the research were an extracted H/sup -/ beam current density of 56 mA/cm/sup 2/ at 23 mA for 5 s pulses and, gas efficiency of 3%, theta/sub perpendicular/ (1/e) approx. 2 +- 1/sup 0/, theta/sub parallel/ (1/e) approx. 1 +- 1/sup 0/, at a beam energy of 25 keV. Negative heavy ion beam impurities were reduced to < 1% at low current densities. H/sup -/ ions are produced prinicpally by positive ion surface conversion using elemental cesium fractional monolayer coverage on a molybdenum converter substrate, which is biased negatively with respect to the anode.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5325671
• Report Number(s): ORNL/TM-7895; ON: DE82016042
• Country of Publication: United States
• Language: English

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ALKALI METALS
ANIONS
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CATHODES
CESIUM
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