Runaway electron generation and mitigation on the European medium sized tokamaks ASDEX Upgrade and TCV

ASDEX Upgrade (AUG) and TCV have recently joined the international eort of better understanding runaway electron (RE) generation and dissipation, aiding the development of the future ITER disruption & runaway electron mitigation system. The AUG post- disruption RE beams can carry up to 400 kA of current and last up to 500 ms. Suppression of REs was achieved with 0.17 barl of argon or 0.7 barl of neon massive gas injection (MGI) into a fully formed beam using the in-vessel valves. A resonant magnetic perturbation conguration was developed that leads to up to a factor of 2 decrease in the RE current. TCV quiescent RE scenarios show RE generation at E=Ec & 15. MGI induced disruptions can achieve a full conversion of Ohmic current into runaways and beam lengths of up to 650 ms. High-Z injections of argon & neon on TCV lead to enhanced RE dissipation, but not a full suppression. Elongated plasmas were found to not generate RE beams. Pre-disruption seed electrons have been found to survive the disruption on both tokamaks, indicating a partially conned core during the quench phase.