Ripple transport in Helical-Axis Advanced Stellarators: A comparison with classical stellarator/torsatrons

Technical Report · Sat Jul 01 04:00:00 EDT 1995

DOI:https://doi.org/10.2172/93468· OSTI ID:93468

Beidler, C D ^[1]; Hitchon, W N.G. ^[2]

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1. Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)
2. Wisconsin Univ., Madison, WI (United States). Dept. of Electrical and Computer Engineering

Calculations of the neoclassical transport rates due to particles trapped in the helical ripples of a stellarator`s magnetic field are carried out, based on solutions of the bounceaveraged kinetic equation. These calculations employ a model for the magnetic field strength, B, which is an accurate approximation to the actual B for a wide variety of stellarator-type devices, among which are Helical-Axis Advanced Stellarators (Helias) as well as conventional stellarators and torsatrons. Comparisons are carried out in which it is shown that the Helias concept leads to significant reductions in neoclassical transport rates throughout the entire long-mean-free-path regime, with the reduction being particularly dramatic in the {nu}{sup {minus}1} regime. These findings are confirmed by numerical simulations. Further, it is shown that the behavior of deeply trapped particles in Helias can be fundamentally different from that in classical stellarator/torsatrons; as a consequence, the beneficial effects of a radial electric field on the transport make themselves felt at lower collision frequency than is usual.

• Research Organization: Wisconsin Univ., Madison, WI (United States). Dept. of Electrical and Computer Engineering
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-85ER53201
• OSTI ID: 93468
• Report Number(s): DOE/ER/53201--T6; ON: DE95015114
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOUNDARY CONDITIONS
KINETIC EQUATIONS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELD RIPPLES
MAGNETIC FIELDS
MONTE CARLO METHOD
NEOCLASSICAL TRANSPORT THEORY
TORSATRON STELLARATORS