  A parallel cut-cell algorithm is described to solve the free boundary problem
of the Grad-Shafranov equation. The algorithm reformulates the free-boundary
problem in an irregular bounded domain and its important aspects include a
searching algorithm for the magnetic axis and separatrix, a surface integral
along the irregular boundary to determine the boundary values, an approach to
optimize the coil current based on a targeting plasma shape, Picard iterations
with Aitken's acceleration for the resulting nonlinear problem and a Cartesian
grid embedded boundary method to handle the complex geometry. The algorithm is
implemented in parallel using a standard domain-decomposition approach and a
good parallel scaling is observed. Numerical results verify the the accuracy
and efficiency of the free-boundary Grad-Shafranov solver.
