Abstract
Transport properties in the W7-AS stellarator and in tokamaks are compared. The parameter dependences and the absolute values of the energy confinement time are similar. Indications are found that the density dependence, which is usually observed in stellarator confinement, can vanish above a critical density. The density dependence in stellarators seems to be similar to that in the linear ohmic confinement regime, which, in small tokamaks, extends to high density values, too. Because of the similarity in the gross confinement properties, transport in stellarators and tokamaks should not be dominated by the parameters which are very different in the two concepts, i.e. magnetic shear, major rational values of the rotational transform and plasma current. A difference in confinement is that there exists evidence for pinches in the particle and, possibly, energy transport channels in tokamaks whereas in stellarators no pinches have been observed, so far. In order to study the effect of plasma current and toroidal electric fields, stellarator discharges were carried out with an increasing amount of plasma current. From these experiments, no clear evidence of a connection of pinches with these parameters is found. The transient response in W7-AS plasmas can be described in terms of a non-local
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Stroth, U;
Burhenn, R;
Geiger, J;
Giannone, L.;
Hartfuss, H J;
Kuehner, G;
Ledl, L;
Simmet, E E;
Walter, H;
[1]
ECRH Team;
W7-AS Team
- Max-Planck-Inst. fuer Plasmaphysik, IPP-Euratom Association, Garching (Germany)
Citation Formats
Stroth, U, Burhenn, R, Geiger, J, Giannone, L., Hartfuss, H J, Kuehner, G, Ledl, L, Simmet, E E, Walter, H, ECRH Team, and W7-AS Team.
Comparative studies of stellarator and tokamak transport.
IAEA: N. p.,
1997.
Web.
Stroth, U, Burhenn, R, Geiger, J, Giannone, L., Hartfuss, H J, Kuehner, G, Ledl, L, Simmet, E E, Walter, H, ECRH Team, & W7-AS Team.
Comparative studies of stellarator and tokamak transport.
IAEA.
Stroth, U, Burhenn, R, Geiger, J, Giannone, L., Hartfuss, H J, Kuehner, G, Ledl, L, Simmet, E E, Walter, H, ECRH Team, and W7-AS Team.
1997.
"Comparative studies of stellarator and tokamak transport."
IAEA.
@misc{etde_573668,
title = {Comparative studies of stellarator and tokamak transport}
author = {Stroth, U, Burhenn, R, Geiger, J, Giannone, L., Hartfuss, H J, Kuehner, G, Ledl, L, Simmet, E E, Walter, H, ECRH Team, and W7-AS Team}
abstractNote = {Transport properties in the W7-AS stellarator and in tokamaks are compared. The parameter dependences and the absolute values of the energy confinement time are similar. Indications are found that the density dependence, which is usually observed in stellarator confinement, can vanish above a critical density. The density dependence in stellarators seems to be similar to that in the linear ohmic confinement regime, which, in small tokamaks, extends to high density values, too. Because of the similarity in the gross confinement properties, transport in stellarators and tokamaks should not be dominated by the parameters which are very different in the two concepts, i.e. magnetic shear, major rational values of the rotational transform and plasma current. A difference in confinement is that there exists evidence for pinches in the particle and, possibly, energy transport channels in tokamaks whereas in stellarators no pinches have been observed, so far. In order to study the effect of plasma current and toroidal electric fields, stellarator discharges were carried out with an increasing amount of plasma current. From these experiments, no clear evidence of a connection of pinches with these parameters is found. The transient response in W7-AS plasmas can be described in terms of a non-local model. As in tokamaks, also cold pulse experiments in W7-AS indicate the importance of non-local transport. (author). 8 refs, 5 figs.}
place = {IAEA}
year = {1997}
month = {Sep}
}
title = {Comparative studies of stellarator and tokamak transport}
author = {Stroth, U, Burhenn, R, Geiger, J, Giannone, L., Hartfuss, H J, Kuehner, G, Ledl, L, Simmet, E E, Walter, H, ECRH Team, and W7-AS Team}
abstractNote = {Transport properties in the W7-AS stellarator and in tokamaks are compared. The parameter dependences and the absolute values of the energy confinement time are similar. Indications are found that the density dependence, which is usually observed in stellarator confinement, can vanish above a critical density. The density dependence in stellarators seems to be similar to that in the linear ohmic confinement regime, which, in small tokamaks, extends to high density values, too. Because of the similarity in the gross confinement properties, transport in stellarators and tokamaks should not be dominated by the parameters which are very different in the two concepts, i.e. magnetic shear, major rational values of the rotational transform and plasma current. A difference in confinement is that there exists evidence for pinches in the particle and, possibly, energy transport channels in tokamaks whereas in stellarators no pinches have been observed, so far. In order to study the effect of plasma current and toroidal electric fields, stellarator discharges were carried out with an increasing amount of plasma current. From these experiments, no clear evidence of a connection of pinches with these parameters is found. The transient response in W7-AS plasmas can be described in terms of a non-local model. As in tokamaks, also cold pulse experiments in W7-AS indicate the importance of non-local transport. (author). 8 refs, 5 figs.}
place = {IAEA}
year = {1997}
month = {Sep}
}