ITER asymmetric error fields and their correction

The locked mode threshold as a consequence of asymmetric error fields is expected to be an order of magnitude more stringent in ITER than in present tokamaks. Analysis is presented which summarizes the error field sources expected in ITER, A statistical approach is developed which combines the PF and TF sources into a single multi-mode predictor. A non-linear optimization technique is used to evaluate performance of the proposed error field correction coil system on the expected error field sources. The system is shown capable of correcting the expected residual machine error fields to below the predicted locked mode threshold.