Three-Dimensional Equilibrium Reconstruction: The V3FIT Code

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Three-Dimensional Equilibrium Reconstruction
The V3FIT Code

• James D. Hanson, John Shields, Stephen F.
  Knowlton
• Auburn University
• Steven P. Hirshman, Edward A. Lazarus
• Oak Ridge National Laboratory
• Lang Lao
• General Atomics

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Equilibrium Reconstruction - Inverse Problem

• Forward Problem, Given parameters p, compute
  model values of signals (diagnostics) Smodel(p)
• Minimize
• Obtain p(model Sobserve)

V3FIT Code Fast, Flexible, Extensible

• Fortran 95, modules, derived types
• VMEC is Equilibrium Solver
• Magnetic Diagnostics for Signals

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First Reconstruction October 2006

• Contour Plot of g2 in parameter space
• CTH Equilibrium, simulated observations
• 12 magnetic diagnostics, 2 parameters
• Jacobian computed by Finite Difference
• Red dots and dashed line - reconstruction path

Future Work

• Code Completion, Algorithm Development
• Benchmark with EFIT, axisymmetric reconstruction
• Interface with Experimentalists
• Add Signal Types Beyond Magnetic Diagnostics
• Other Equilibrium Solvers