Physics of Compact Advanced Stellarators

Technical Report · Tue Aug 14 00:00:00 EDT 2001

DOI:https://doi.org/10.2172/787903· OSTI ID:787903

Zarnstorff, M C; Berry, L A; Brooks, A; Fredrickson, E; Fu, G -Y; Hirshman, S; Hudson, S; Ku, L -P; Lazarus, E; Mikkelsen, D; Monticello, D; Neilson, G H; Pomphrey, N; Reiman, A; Spong, D; Strickler, D; Boozer, A; Cooper, W A; Goldston, R; Hatcher, R ; Isaev, M; Kessel, C; Lewandowski, J; Lyon, J; Merkel, P; Mynick, H; Nelson, B E; Nuehrenberg, C; Redi, M; Reiersen, W; Sanchez, R; Schmidt, J; White, R B

Compact optimized stellarators offer novel solutions for confining high-beta plasmas and developing magnetic confinement fusion. The 3-D plasma shape can be designed to enhance the MHD stability without feedback or nearby conducting structures and provide drift-orbit confinement similar to tokamaks. These configurations offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low-aspect ratio, high beta-limit, and good confinement of advanced tokamaks. Quasi-axisymmetric equilibria have been developed for the proposed National Compact Stellarator Experiment (NCSX) with average aspect ratio 4-4.4 and average elongation of approximately 1.8. Even with bootstrap-current consistent profiles, they are passively stable to the ballooning, kink, vertical, Mercier, and neoclassical-tearing modes for beta > 4%, without the need for external feedback or conducting walls. The bootstrap current generates only 1/4 of the magnetic rotational transform at beta = 4% (the rest is from the coils), thus the equilibrium is much less nonlinear and is more controllable than similar advanced tokamaks. The enhanced stability is a result of ''reversed'' global shear, the spatial distribution of local shear, and the large fraction of externally generated transform. Transport simulations show adequate fast-ion confinement and thermal neoclassical transport similar to equivalent tokamaks. Modular coils have been designed which reproduce the physics properties, provide good flux surfaces, and allow flexible variation of the plasma shape to control the predicted MHD stability and transport properties.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE Office of Science (US)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 787903
• Report Number(s): PPPL-3597; TRN: US0110753
• Resource Relation: Other Information: PBD: 14 Aug 2001
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASPECT RATIO
BOOTSTRAP CURRENT
HIGH-BETA PLASMA
MAGNETIC CONFINEMENT
ROTATIONAL TRANSFORM
SPATIAL DISTRIBUTION
STELLARATORS
PLASMA INSTABILITY
MAGNETOHYDRODYNAMICS