Lessons learned executing the non-disruptive compass scan method at JET towards error field identification experiments in ITER

In preparation for error field (EF) identification experiments in ITER, a series of experiments have been conducted at JET to test the portability of the non-disruptive compass scan, a method originally designed and tested in DIII-D (Paz-Soldan et al 2022 Nucl. Fusion 62 126007). In this context, various strategies for enabling magnetic island healing have been assessed, including the injection of pellets of different sizes and frequencies, neutral beam power injection, and EF correction by 3D externally applied fields. The experimental results provide valuable insights that are assisting the preparation of EF identification studies during ITER commissioning, including the design of the locked mode detector. This support function is of primary importance, as it will trigger the control actions for magnetic island healing, i.e. turning off the EF actuator current to eliminate the drive for the magnetic island, and asynchronously increasing the plasma density to stabilize it.