An intense lithium ion beam source using vacuum baking and discharge cleaning techniques

Journal Article · Tue Oct 01 00:00:00 EDT 1991 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.349260· OSTI ID:5151872

Moschella, J J; Kusse, B R; Longfellow, J P; Olson, J C ^[1]

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1. Laboratory of Plasma Studies, Cornell University, Ithaca, New York (USA)

We have developed a high-purity, intense, lithium ion beam source which operates at 500 kV and 120 A/cm{sup 2} with pulse widths of 125 ns full width half maximum. The beams were generated using a lithium chloride anode in planar magnetically insulated geometry. We have found that the combination of vacuum baking of the anode at 250 {degree}C followed by the application of 100 W of pure argon, steady-state, glow discharge cleaning reduced the impurity concentration in the beam to approximately 10% (components other than chlorine or lithium were considered impurities). Although the impurities were low, the concentration of chlorine in the 1+ and 2+ charge states was significant ({similar to}25%). The remaining 65% of the beam consisted of Li{sup +} ions. Without the special cleaning process, over half the beam particles were impurities. It was determined that these impurities entered the beam at the anode surface but came originally from material in the vacuum chamber. After the cleaning process, recontamination was observed to occur in approximately 6 min. This long recontamination time, which was much greater than the expected monolayer formation time, was attributed to the elevated temperature of the anode. We also compared the electrical characteristics of the beams produced by LiCl anodes to those generated by a standard polyethylene proton source. In contrast to the polyethylene anode, the LiCl source exhibited a higher impedance, produced beams of lower ion current efficiency and had longer turn on times.

• OSTI ID: 5151872
• Journal Information: Journal of Applied Physics; (United States), Vol. 70:7; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
LITHIUM IONS
ION SOURCES
ANODES
BAKING
DESIGN
GLOW DISCHARGES
LITHIUM CHLORIDES
PERFORMANCE
ALKALI METAL COMPOUNDS
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
ELECTRIC DISCHARGES
ELECTRODES
HALIDES
HALOGEN COMPOUNDS
HEATING
IONS
LITHIUM COMPOUNDS
LITHIUM HALIDES
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions