Experimental investigations with respect to the applicability of the Bohm criterion

The streaming of a plasma in a magnetic nozzle field in front of a terminating target is studied by means of laser induced fluorescence. In contrast to expectations basing on Bohm’s criterion it is found that the flow is generally sub-sonic in the region behind the last magnetic coil. Half-sided Max...

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Bibliographic Details
Published in:	Journal of nuclear materials Vol. 337-339; pp. 201 - 205
Main Authors:	Lunt, T., Ezumi, N., Bohmeyer, W., Fussmann, G.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-03-2005
Subjects:	Argon Laser induced fluorescence Scrape-off layer flow Sheath 52.65 Laser induced fluorescence E0500 52.40.H 52.30 Argon Scrape-off layer flow Sheath
Online Access:	Get full text
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Summary:	The streaming of a plasma in a magnetic nozzle field in front of a terminating target is studied by means of laser induced fluorescence. In contrast to expectations basing on Bohm’s criterion it is found that the flow is generally sub-sonic in the region behind the last magnetic coil. Half-sided Maxwellian ion-distribution functions with Mach numbers around 0.5 are typical for standard recycling conditions within a distance of the mean free path length from the target. Larger flow velocities, possibly exceeding M=1, are however observed under maximum gas pumping conditions. The importance of the recycling neutrals with respect to the streaming behavior is also corroborated by numerical simulations.
Bibliography:	SourceType-Scholarly Journals-2 ObjectType-Feature-2 ObjectType-Conference Paper-1 content type line 23 SourceType-Conference Papers & Proceedings-1 ObjectType-Article-3
ISSN:	0022-3115 1873-4820
DOI:	10.1016/j.jnucmat.2004.10.147