Locked-mode avoidance and recovery without external momentum input

Error-field-induced locked-modes (LMs) have been studied in C-Mod at ITER toroidal fields without NBI fueling and momentum input. The use of ICRH heating in synch with the error-field ramp-up resulted in a successful delay of the mode-onset when $P_{ICRH}> 1$ MW and a transition into H-mode when $P_{ICRH}> 2$ MW. The recovery experiments consisted in applying ICRH power during the LM non-rotating phase successfully unlocking the core plasma. The ``induced'' toroidal rotation was in the counter-current direction, restoring the direction and magnitude of the toroidal flow before the LM formation, but contrary to the expected Rice-scaling in the co-current direction. However, the LM occurs near the LOC/SOC transition where rotation reversals are commonly observed. Once $P_{ICRH}$ is turned off, the core plasma ``locks'' at later times depending on the evolution of $n_{e}$ and $V_{t}$. This work was performed under US DoE contracts including DE-FC02-99ER54512 and others at MIT and DE-AC02-09CH11466 at PPPL.