| Center
for Extended Magnetohydrodynamic Modeling
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| Figure
10 M3D simulation of the proposed
compact quasi-axisymmetric (QAS) stellarator. Equi-pressure
surface of the li383 case with ß exceeding the design
limit shows the nonlinear ballooning mode steepening to
form a ribbon-like structure. |
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The Center for Extended Magnetohydrodynamic Modeling (CEMM)
will extend and apply computer codes (M3D and NIMROD) that will
enable a realistic assessment of the mechanisms leading to disruptive
and other stability limits in the present and next generation
of fusion devices. With an improvement in the efficiency of
codes and with the extension of the leading 3D nonlinear magneto-fluid
models of hot, magnetized fusion plasmas, this research will
pioneer new plasma simulations of unprecedented realism and
resolution.
The Multi-Level 3D (M3D) project simulates plasmas using
multiple levels of physics, geometry, and grid models in one
code package. The M3D code has been extended to fundamentally
non-axisymmetric and small aspect ratio, R/a 
1, configurations. Applications include the non-linear stability
of the NSTX spherical torus and of the spherical pinch, as
well as the relaxation of stellarator equilibria (Figure 10).
The fluid level physics model has been extended to evolve
the anisotropic pressures 
and 
for the ion and electron species and has been applied to magnetic
island evolution. Further development of the M3D code is being
done in collaboration with the TOPS
Center.
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| Figure
11 Poloidal flux contours during
successive phases of co-helicity reconnection, computed
with MRC. |
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The CEMM and APDEC
centers are collaborating to apply the CHOMBO adaptive mesh
refinement framework to MHD problems of importance to fusion
energy. They are targeting two primary applications: magnetic
reconnection including Hall physics, and pellet injection
and ablation. The Magnetic Reconnection Code (MRC) uses a
fixed, non-uniform rectangular mesh to resolve the different
spatial scales in the reconnection problem. The resistive
MHD version uses an implicit/explicit hybrid method, while
the two-fluid version uses an alternating-direction implicit
(ADI) method with high-order artificial dissipation. MRC has
proven useful for comparing several different theories of
collisional and collisionless reconnection (Figure 11).
INVESTIGATORS
S. C. Jardin, J. A. Breslau, J. Chen, G. Fu, S. Klasky, W.
Park, and R. Samteney, Princeton Plasma Physics Laboratory;
J. Callen, C. Hegna, and C. Sovinec, University of Wisconsin;
E. Held, Utah State University; C. Kim and S. Parker, University
of Colorado; S. Kruger and D. Schnack, Science Applications
International Corp.; R. Nebel, Los Alamos National Laboratory;
D. Schissel, General Atomics; L. E. Sugiyama, Massachusetts
Institute of Technology; H. R. Strauss, New York University;
F. Waelbroeck, University of Texas.
PUBLICATIONS
L. E. Sugiyama, W. Park, H. R. Strauss, S. R. Hudson, D. Stutman,
and X.-Z. Tang, “Studies of spherical tori, stellarators
and anisotropic pressure with the M3D code,” Nuclear
Fusion 41, 739 (2001).
URL
http://w3.pppl.gov/CEMM/ |
