This title appears in the Scientific Report :
2006
Please use the identifier:
http://hdl.handle.net/2128/1890 in citations.
Please use the identifier: http://dx.doi.org/10.1088/0741-3335/48/5A/S30 in citations.
On the difference of H-mode power threshold in divertor and limiter tokamaks
On the difference of H-mode power threshold in divertor and limiter tokamaks
The difference in the H-mode power threshold in divertor and limiter configurations is numerically investigated by analysing the effect of boundary conditions imposed on the last closed magnetic surface (LCMS) and given by prescribed density and temperature e-folding lengths, delta(n) and delta(T),...
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Personal Name(s): | Kalupin, D. |
---|---|
Tokar, M. Z. / Unterberg, B. / Loozen, X. / Pilipenko, D. / Zagórski, R. | |
Contributing Institute: |
Institut für Plasmaphysik; IPP |
Published in: | Plasma physics and controlled fusion, 48 (2006) S. A309 - A317 |
Imprint: |
Bristol
IOP Publ.
2006
|
Physical Description: |
A309 - A317 |
DOI: |
10.1088/0741-3335/48/5A/S30 |
Document Type: |
Journal Article |
Research Program: |
Fusion |
Series Title: |
Plasma Physics and Controlled Fusion
48 |
Subject (ZB): | |
Link: |
Get full text OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1088/0741-3335/48/5A/S30 in citations.
The difference in the H-mode power threshold in divertor and limiter configurations is numerically investigated by analysing the effect of boundary conditions imposed on the last closed magnetic surface (LCMS) and given by prescribed density and temperature e-folding lengths, delta(n) and delta(T), respectively. It is demonstrated that the variation of delta(n) and delta(T) significantly affects the H-mode power threshold. This is explained by the change in the balance between conductive and convective heat losses at the edge. For the ratio delta(n)/delta(T) large enough, when the convective loss does not exceed 45% of the total power, the threshold agrees well with the experimental multi-machine scaling for divertor tokamaks. With reduction in delta(n)/delta(T) and increase in convective loss above this critical level, the power threshold significantly exceeds the scaling, in agreement with observations on different limiter tokamaks. By considering the power and particle balances in the scrape-off layer it is shown that the ratio delta(n)/delta(T) is controlled by the distance which recycling neutrals pass before entering the confined plasma and which is normally much larger in divertor machines than in the limiter ones. The calculations for the limiter tokamak TEXTOR have predicted the experimentally found conditions for the L-H transition in advance. |