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Comparative studies of stellarator and tokamak transport

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  More>>
Authors:
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
  1. Max-Planck-Inst. fuer Plasmaphysik, IPP-Euratom Association, Garching (Germany)
Publication Date:
Sep 01, 1997
Product Type:
Conference
Report Number:
CONF-961005-; STI/PUB-1004.
Reference Number:
SCA: 700340; 700410; PA: AIX-29:009158; EDB-98:030828; SN: 98001920519
Resource Relation:
Conference: 16. International Atomic Energy Agency (IAEA) international conference on plasma physics and controlled nuclear fusion research, Montreal (Canada), 7-11 Oct 1996; Other Information: PBD: Sep 1997; Related Information: Is Part Of Fusion energy 1996. V. 2. Proceedings of the 16. international conference; PB: 1003 p.; Proceedings series
Subject:
70 PLASMA PHYSICS AND FUSION; CHARGED-PARTICLE TRANSPORT; CONFINEMENT TIME; ELECTRIC DISCHARGES; ELECTRON TEMPERATURE; NEOCLASSICAL TRANSPORT THEORY; PLASMA DENSITY; TOKAMAK TYPE REACTORS; WENDELSTEIN-7 STELLARATOR
OSTI ID:
573668
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0074-1884; Other: ISBN 92-0-102997-7; TRN: XA9745347009158
Submitting Site:
INIS
Size:
pp. 127-133
Announcement Date:

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}
}