OPTIMUM CONFINEMENT IN THE WENDELSTEIN 7-AS STELLARATOR

被引:33
作者
WELLER, A [1 ]
BRAKEL, R [1 ]
BURHENN, R [1 ]
ERCKMANN, V [1 ]
GRIGULL, P [1 ]
HARTFUSS, HJ [1 ]
MAASSBERG, H [1 ]
RENNER, H [1 ]
RINGLER, H [1 ]
SARDEI, F [1 ]
SCHNEIDER, U [1 ]
AFANASIEV, V [1 ]
BALDZUHN, J [1 ]
BOMBA, B [1 ]
BRAKEL, R [1 ]
BURHENN, R [1 ]
BUCHSE, R [1 ]
CATTANEI, G [1 ]
DODHY, A [1 ]
DORST, D [1 ]
ELSNER, A [1 ]
ENDLER, M [1 ]
ENGELHARDT, K [1 ]
ERCKMANN, V [1 ]
ESTRADA, T [1 ]
GASPARINO, U [1 ]
GEISSLER, S [1 ]
GIANNONE, L [1 ]
GRIEGER, G [1 ]
GRIGULL, P [1 ]
HACKER, H [1 ]
HARTFUSS, HJ [1 ]
HIDALGO, C [1 ]
HILDEBRANDT, D [1 ]
HOFMANN, J [1 ]
IZVOZCHIKOV, A [1 ]
JAENICKE, R [1 ]
JUNKER, J [1 ]
KARGER, F [1 ]
KICK, M [1 ]
KONDO, K [1 ]
KROISS, H [1 ]
KUHNER, G [1 ]
LAKICEVIC, I [1 ]
LAZAROS, A [1 ]
MAASSBERG, H [1 ]
MAHN, C [1 ]
MCCORMICK, K [1 ]
NIEDERMEYER, H [1 ]
OHLENDORF, W [1 ]
机构
[1] UNIV STUTTGART,INST PLASMAFORSCH,W-7000 STUTTGART 80,GERMANY
关键词
STELLARATOR; W7-AS; CONFINEMENT; IMPURITY CONTROL; HEAT CONDUCTION; PARTICLE TRANSPORT; IMPURITY TRANSPORT; STABILITY;
D O I
10.1088/0741-3335/33/13/007
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
Optimum confinement is realized in WENDELSTEIN 7-AS (low shear modular stellarator, R = 2 m, a congruent-to 0.18 m) by wall conditioning and by properly adjusting the parameters determining the magnetic field configuration. In particular low order rational values of the rotational transform have to be excluded from the confinement region or sufficient shear must be established by internal currents. The effective heating of net current free plasmas by ECRF (P less-than-or-similar-to 0.8 MW, 70 GHz) and neutral beam injection (NBI, P less-than-or-similar-to 1.5 MW, 45 kV) involves different plasma parameters and transport regimes. Stationary plasmas are generally produced by ECRF, whereas density and impurity control is a severe problem during NBI. This has initiated different kinds of impurity and particle control scenarios (carbonization, boronization and edge cooling). Thus, < beta > less-than-or-similar-to 1.1% (1.25 T) could be achieved. An extended parameter range with electron temperatures of 200 eV less-than-or-equal-to T(e) less-than-or-equal-to 3 keV, ion temperatures of 100 eV less-than-or-equal-to T(i) less-than-or-equal-to 0.7 keV and electron densities of 10(19) less-than-or-equal-to n(e) less-than-or-equal-to 3 . 10(20) m-3 was accessible. The characteristics of the energy confinement (confinement times up to 35 ms are observed in low power/low density ECRF heated and up to 25 ms in high power/high density NBI heated plasmas) and the particle and impurity transport are described and related to the specific heat and particle sources. The investigations comprise the analysis of electron and ion heat conductivity, particle transport modelling based on H-alpha measurements at relevant locations around the torus and impurity transport studies by laser blow-off experiments. The influence of the ambipolar electric field is discussed.
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收藏
页码:1559 / 1578
页数:20
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