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  4. Threshold power for the transition into H-mode for H, D, and He plasmas in TCV
 
research article

Threshold power for the transition into H-mode for H, D, and He plasmas in TCV

Behn, R
•
Labit, B
•
Karpushov, A
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2015
Plasma Physics and Controlled Fusion

The threshold power for the transition into H-mode with hydrogen (H), deuterium (D), and helium (He) as majority ion species has been evaluated from a series of dedicated experiments on the tokamak TCV. Identical plasma configurations with a single-null X-point and favorable direction of the ion del B drift have been chosen. The input power was varied via the plasma current and L-H transitions were obtained with Ohmic heating alone. Under these conditions and for electron densities in the range of 6-7.10(19) m(-3) the threshold power compared to D increased by 1.75 for H and 1.45 for He, respectively. For D and He, the measured power levels are in good agreement with the predictions of the commonly used scaling law. In the case of H, transitions into H-mode were observed already at power levels of about 80% of the expected threshold power. Our results have also been analyzed on the basis of a physics-based scaling, which includes more parameters and applies to all ion species. Using the case of D as reference, we find that the increase in threshold power for He follows the predictions. For H there is a noticeable disagreement which may partly be explained by uncertainties in the relevant plasma parameters. The new scaling implies a strong dependence on the values of the electron temperature at the separatrix. For the present study, only data up to a normalized radius of 0.95 were available. More precise measurements of the edge temperature profiles may help to resolve the issue.

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Type
research article
DOI
10.1088/0741-3335/57/2/025007
Web of Science ID

WOS:000350133900007

Author(s)
Behn, R
Labit, B
Karpushov, A
Duval, BP
Martin, Y
Porte, L
Corporate authors
TCV team
Date Issued

2015

Publisher

Iop Publishing Ltd

Published in
Plasma Physics and Controlled Fusion
Volume

57

Issue

2

Article Number

025007

Subjects

tokamak

•

H mode

•

threshold

•

scaling law

•

ohmic heating

•

ion species

URL

URL

https://crpplocal.epfl.ch/pinboard/jpapers/1401608.pdf
Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
CRPP  
SPC  
Available on Infoscience
December 2, 2014
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/109171
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