Abstract Details

Add files

Investigation of Edge Physics on HSX using EMC3-EIRENE

Author: Aaron Bader
Requested Type: Consider for Invited
Submitted: 2012-12-07 15:12:58

Co-authors: A.R.Akerson, D.T.Anderson, Y.Feng, C.C.Hegna, J.Smoniewski, J.N.Talmadge

Contact Info:
University of Wisconsin - Madison
1500 Engineering Drive, 511 ER
Madison, Wisconsin   53706
United States

Abstract Text:
We investigate edge physics in the boundary of the HSX
device using EMC3-EIRENE. Stellarator edges have
complicated 3D geometries that include field lines with long
connection lengths and possibly magnetic islands that
support parallel flow structures. Friction between
counter-streaming flows in adjacent islands can modify
momentum transport and impact the transition into a
high-recycling regime. Therefore, edge transport models for
stellarators must include terms perpendicular to the
magnetic field. EMC3-EIRENE is a Monte-Carlo code that
solves the fluid equations in arbitrary 3D geometries on
both open and closed field lines, and includes cross-field
effects. In this paper, we investigate several magnetic
configurations that can be produced using the standard HSX
coil set. The configurations vary in their edge properties,
ranging from a last closed flux surface bounded by large
islands that intersect the vessel wall, to an LCFS bounded
by small islands that are separated from the wall by a
stochastic region. We present simulations of the edge
behavior using parameters achievable in the HSX device.
These simulations predict the existence of strong flows in
the edge. Measurements of these flow structures with a
6-pin Gundestrup mach probe are underway and we present
comparisons between EMC3-EIRENE simulations and experimental
data. Because of the accessibility of the HSX edge plasma
to physical probes, the experiment is ideal for
characterizing edge properties that are more difficult to
measure on other devices. We also extrapolate to a
large-sized machine modeled on HSX that can reach edge
densities and temperatures relevant for accessing high
recycling and detached divertor regimes, and discuss the
implications of edge island characteristics in transitioning
into high-recycling and detached regimes.

Work supported by DOE-SC0006103 and DE-FG02-93ER54222

Characterization: 1.4

Comments: