Energetic particle transport in stellarators

One of the primary requirements for an effective fusion power plant (FPP) is the sufficient confinement of the fusion products, the energetic alpha particles produced in the deuterium-tritium reaction. These energetic particles must be confined sufficiently long such that they can deposit their energy in the thermal bulk and maintain the fusion burn. Furthermore, rapid losses must be avoided to mitigate destruction of the material walls of the fusion device. Energetic particles have historically been challenging to confine in stellarator magnetic confinement devices due to the possibility of unconfined orbits in the three-dimensional (3D) magnetic field. With recent advances in the numerical optimization of stellarator magnetic fields, new configurations have been obtained with excellent confinement of fusion-born alpha particles in the absence of perturbations. This breakthrough demonstrates that a stellarator may serve as an effective fusion power plant. There is, however, the potential for enhanced alpha losses due to interactions with perturbations in the background plasma. In particular, experimental measurements on magnetic confinement devices indicate that the resonant interactions between energetic particles (EPs) and shear Alfven waves drive substantial transport. Alfvenic activity is considered the major limitation to alpha particle confinement in a burning plasma. 

Our research focuses on the development of reduced models for energetic particle transport in 3D magnetic fields and the mitigation of transport through numerical optimization strategies.