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A. Reiman,
L. Ku,
D. Monticello,
S. Hirshman,
S. Hudson,
C. Kessel,
E. Lazarus,
D. Mikkelsen,
M. Zarnstorff,
L. A. Berry, [......],
M. Redi,
W. Reiersen,
P. Rutherford,
R. Sanchez,
J Schmidt,
D. Spong,
D. Strickler,
A. Subbotin, P. Valanju,
R White
[show abstract]
[hide abstract]
ABSTRACT: Strategies for the improvement of quasiaxisymmetric stellarator configurations are explored. Calculations of equilibrium flux surfaces for candidate configurations are also presented. One optimization strategy is found to generate configurations with improved neoclassical confinement, simpler coils with lower current density, and improved flux surface quality relative to previous designs. The flux surface calculations find significant differences in the extent of islands and stochastic regions between candidate configurations. (These calculations do not incorporate the predicted beneficial effects of perturbed bootstrap currents.) A method is demonstrated for removing low order islands from candidate configurations by relatively small modifications of the configuration. One configuration is identified as having particularly desirable properties for a proposed experiment. (C) 2001 American Institute of Physics.
Physics of Plasmas 05/2001; 8(5):2083. · 2.15 Impact Factor
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A. Reiman,
L. Ku,
D. Monticello,
S. Hirshman,
S. Hudson,
C. Kessel,
E. Lazarus,
D. Mikkelsen,
M. Zarnstorff,
L. Berry, [......],
M. Redi,
W. Reiersen,
P. Rutherford,
R. Sanchez,
J. Schmidt,
D. Spong,
D. Strickler,
A. Subbotin, P. Valanju,
R. White
Physics of Plasmas 01/2001; 8(5):2083. · 2.15 Impact Factor
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A. Reiman,
G Fu,
S. Hirshman,
L. Ku,
D. Monticello,
H. Mynick,
M. Redi,
D. Spong,
M. Zarnstorff,
B. Blackwell, [......],
C. Nuhrenberg,
M Okamoto,
N. Pomphrey,
W. Reiersen,
R. Sanchez,
J Schmidt,
A. Subbotin, P. Valanju,
K.Y. Watanabe,
R White
[show abstract]
[hide abstract]
ABSTRACT: Key physics issues in the design of a high-beta quasi-axisymmetric stellarator configuration are discussed. The goal of the design study is a compact stellarator configuration with aspect ratio comparable to that of tokamaks and good transport and stability properties. Quasi-axisymmetry has been used to provide good drift trajectories. Ballooning stabilization has been accomplished by strong axisymmetric shaping, yielding a stellarator configuration whose core is in the second stability regime for ballooning modes. A combination of externally generated shear and non-axisymmetric corrugation of the plasma boundary provides stability to external kink modes even in the absence of a conducting wall. The resulting configuration is also found to be robustly stable to vertical modes, increasing the freedom to perform axisymmetric shaping. Stability to neoclassical tearing modes is conferred by a monotonically increasing i profile. A gyrokinetic delta f code has been used to confirm the adequacy of the neoclassical confinement. Neutral beam losses have been evaluated with Monte Carlo codes.
Plasma Physics and Controlled Fusion 12/1999; 41(12):B273. · 2.42 Impact Factor
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A. Reiman,
G. Fu,
S. Hirshman,
L. Ku,
D. Monticello,
H. Mynick,
M. Redi,
D. Spong,
M. Zarnstorff,
B. Blackwell, [......],
C. Nuehrenberg,
M. Okamoto,
N. Pomphrey,
W. Reiersen,
R. Sanchez,
J. Schmidt,
A. Subbotin, P. Valanju,
K. Watanabe,
R. White
Plasma Physics and Controlled Fusion 01/1999; 41:B273. · 2.42 Impact Factor
