In the TJ-II stellarator, a medium-sized heliac device that operates at high rotational transform and low magnetic shear, a close relationship is identified between abrupt changes in transport (in the form of radial fluxes, edge or internal transport barriers), broadband magnetohydrodynamic (MHD) events and the location of magnetic resonances. The observations are based on the local behaviour of plasma radiation. Phenomena that appear like sawteeth and crashes in tokamaks are found in practically all kinds of plasmas and show intensities and repetition rates that depend on plasma parameters. The magnetic resonances are suggested as important transport regulators in normal operation.
Localized electromagnetic modes in MHD stable regime of the TJ-II Heliac