Thumbnail
Access Restriction
Open

Author Nachtrieb, R. ♦ LaBombard, B.
Sponsorship (US)
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher The American Physical Society
Language English
Subject Keyword ENERGY STORAGE ♦ BATTERY CHARGE STATE ♦ CONVECTION ♦ DIFFUSION ♦ ELECTRON TEMPERATURE ♦ HELIUM ♦ HELIUM 3 ♦ HELIUM I ♦ IONIZATION ♦ MASS SPECTROMETERS ♦ PHYSICS ♦ PLASMA ♦ TRANSPORT ♦ VELOCITY
Abstract {sup 3}He gas was puffed from the wall into Ohmic low confinement-mode discharges of the Alcator C-Mod [I. H. Hutchinson , Phys. Plasmas 1, 1551 (1994)] tokamak and the charged states were measured near the wall with the omegatron ion mass spectrometer. Analysis of the data shows that the concentrations of singly- and doubly-ionized helium near the wall are approximately equal. The electron temperature and density at the omegatron are too low to account for ionization of helium in the local flux tube, therefore the helium is ionized in a hotter region of the edge plasma and is transported to the omegatron. A simple one-dimensional radial transport model reproduces the observed values of charge state flux and density, but only if rapid cross-field transport is included, increasing with distance from the separatrix. A constant cross-field diffusion coefficient of order 2m{sup 2}/s and an outward convection velocity profile increasing to of order 100 m/s in the far scrape-off layer is implied.
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 2000-11-01
Publisher Place United States
Journal Physics of Plasmas
Volume Number 7
Issue Number 11


Open content in new tab

   Open content in new tab