Controlled magnetic confinement fusion offers the possibility of an inexhaustible supply of energy with zero greenhouse gas emissions. Fusion energy research is now poised to advance rapidly due to a large international investment ($16 billion) in ITER (the International Thermonuclear Experimental Reactor). ITER, with a power gain of over five, will explore the uncharted physics of burning plasmas, in which the energy liberated from the confined products of reaction exceeds the energy invested in heating the plasma. Burning plasmas are energetically complex nonthermal systems, in which a significant fraction of the stored energy resides in beam-heating-driven fast ions (~1 MeV) and fusion-reaction-product helium ions (3.5 MeV alpha particles). Neutral beams inject momentum into the plasma, driving rotation, and currents associated with these beams can change the magnetic configuration.
As both beam and alpha particles undergo collisions with the background plasma they lose energy and can drive electromagnetic modes of the plasma. At large amplitude these modes have been observed to evolve into long-lived "helical" structures in several machines, notably the Mega Ampere Spherical Tokamak of the Culham Centre for Fusion Energy. In this project we investigate the role of energetic particles during the transition from bursting fishbone to a long-living mode.
The project builds on an existing collaboration between the ANU and the Culham Centre for Fusion Energy.