pub fn solve_force_balance(
config: &mut ReactorConfig,
grid: &Grid2D,
r_target: f64,
z_target: f64,
control_coil_indices: &[usize],
) -> FusionResult<(usize, f64)>Expand description
Newton-Raphson force balance solver.
Adjusts outer coil currents (PF3, PF4) to achieve zero radial force at the target position.
Returns the number of iterations and final force residual.