Measurements of classical transport of fast ions

Journal Article · Sun May 15 04:00:00 EDT 2005 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1905863· OSTI ID:20722040

Zhao, L; Heidbrink, W W; Boehmer, H; McWilliams, R; Leneman, D; Vincena, S ^[1]

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1. Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

To study the fast-ion transport in a well controlled background plasma, a 3-cm diameter rf ion gun launches a pulsed, {approx}300 eV ribbon shaped argon ion beam parallel to or at 15 deg. to the magnetic field in the Large Plasma Device (LAPD) [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)] at UCLA. The parallel energy of the beam is measured by a two-grid energy analyzer at two axial locations (z=0.32 m and z=6.4 m) from the ion gun in LAPD. The calculated ion beam slowing-down time is consistent to within 10% with the prediction of classical Coulomb collision theory using the LAPD plasma parameters measured by a Langmuir probe. To measure cross-field transport, the beam is launched at 15 deg. to the magnetic field. The beam then is focused periodically by the magnetic field to avoid geometrical spreading. The radial beam profile measurements are performed at different axial locations where the ion beam is periodically focused. The measured cross-field transport is in agreement to within 15% with the analytical classical collision theory and the solution to the Fokker-Planck kinetic equation. Collisions with neutrals have a negligible effect on the beam transport measurement but do attenuate the beam current.

• OSTI ID: 20722040
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 12; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ARGON IONS
BEAM-PLASMA SYSTEMS
CHARGED-PARTICLE TRANSPORT
FOKKER-PLANCK EQUATION
ION BEAMS
LANGMUIR PROBE
PLASMA GUNS