LAUSR

The role of the COMPASS tokamak in research of generation, con nement and losses of Runaway Electron (RE) population is presented. Recently, two major groups of experiments aimed at improved understanding and control of the REs have been pursued. First, the e ects of the Massive Gas Injection (MGI, ∼ 10 Ar/Ne particles) and impurity seeding (∼ 10 particles) were studied systematically. The observed phenomena include generation of the post-disruption RE beam and current conversion from plasma to RE. Zero loop voltage control was implemented in order to study the decay in simpli ed conditions. A distinctive drop of background plasma temperature and electron density was observed following an additional deuterium injection into the RE beam. The loop voltage control the parametric dependence of the current decay rate dI/dt can be studied systematically and possibly extrapolated to larger RE experiments at COMPASS in support of the EUROfusion research 2 facilities. Second, recent results of experiments focused on the role of the magnetic eld in physics of RE were analysed. In this contribution, special attention is given to the observed e ects of the Resonant Magnetic Perturbation (RMP) on the RE population. The bene ts of the RE experiments on COMPASS was reinforced by diagnostic enhancements (fast cameras, Cherenkov detector, vertical ECE etc.) and modelling e orts (in particular, coupling of the METIS and LUKE codes).