Lithium-fluoride flashover ion source cleaned with a glow discharge and irradiated with vacuum-ultraviolet radiation
We have studied methods of varying the ion species generated by a lithium-fluoride overcoated anode in a 0.5-MV magnetically insulated ion diode. We found that cleaning the anode surface with a 13.6-MHz rf glow discharge or illuminating the anode with a pulsed soft x-ray, vacuum-ultraviolet (XUV) radiation source just before the accelerator pulse significantly altered the ion species of the ion beam produced by the diode. The glow-discharge plasma removed adsorbates (carbon, hydrogen, and oxygen) from the surface of the LiF flashover source. The ions seen were lithium and hydrogen. Unfortunately, the diode impedance with a lithium-fluoride anode was high and the ion efficiency was low; however, XUV irradiation of the surface dramatically lowered the impedance by desorbing neutrals from the ion source via photon-stimulated desorption. Current densities of ten times the Child--Langmuir space-charge limit were achieved under XUV irradiation. In particular, ion currents increased by over a factor of 3 when 12 mJ/cm/sup 2/ of XUV radiation was used. However, with XUV irradiation the largest fraction of ions were fluorine, oxygen, carbon, and hydrogen, not lithium.
- Research Organization:
- Pulsed Power Directorate, Sandia National Laboratories, Albuquerque, New Mexico 87185
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5577086
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 63:1; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700208* -- Fusion Power Plant Technology-- Inertial Confinement Technology
ACCELERATORS
ALKALI METAL COMPOUNDS
ANODES
BEAM PRODUCTION
BEAMS
CHARGED PARTICLES
CLEANING
ELECTRIC DISCHARGES
ELECTRODES
FABRICATION
FLUORIDES
FLUORINE COMPOUNDS
GLOW DISCHARGES
HALIDES
HALOGEN COMPOUNDS
ION BEAMS
ION SOURCES
IONS
LITHIUM 7 BEAMS
LITHIUM COMPOUNDS
LITHIUM FLUORIDES
LITHIUM HALIDES
LITHIUM IONS
PARTICLE BEAM FUSION ACCELERATOR
SURFACE CLEANING
SURFACE FINISHING