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Dynamic concentration of positive ions near the axis of an electron plasma column

Journal Article · · Phys. Fluids; (United States)
DOI:https://doi.org/10.1063/1.864481· OSTI ID:5453360
A steady-state non-neutral plasma, generated by Penning discharge, is used as a focusing element for MeV ion beams. An almost pure electron plasma column is produced which has nearly constant density (10/sup 9/--10/sup 10/ cm/sup -3/) inside a radius of several millimeters. The background gas is at a pressure of 10/sup -7/ torr or less. A model calculation is presented which shows that although orbital damping is negligible, positive ions created by electron-neutral collisions are dynamically concentrated near the axis of the plasma. Light emission by excited ions in the plasma is observed to be brightest in a thin line along the axis. The measured radial profile of relative light intensity is in good agreement with the calculated ion distribution. A radial charge density profile of the plasma, which is inferred from beam deflection measurements, is depressed by several percent near the axis due to positive ions concentrated there.
Research Organization:
Department of Physics, University of Oregon, Eugene, Oregon 97403
OSTI ID:
5453360
Journal Information:
Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 27:1; ISSN PFLDA
Country of Publication:
United States
Language:
English