Good confinement of the bulk plasma and fusion-generated alpha particles are two basic design properties of a fusion reactor. First, small radial energy fluxes are necessary for the plasma to achieve fusion-relevant conditions. In turn, fusion-born alpha particles are expected to contribute to heat the plasma, which requires their confinement time to be sufficiently long. In stellarators,...
Simulating global plasma instabilities and turbulence in stellarators with gyrokinetic codes is significantly more complicated and computationally expensive than in tokamaks and, partly because of this, the field is significantly less developed in stellarators than in the tokamak counterpart. The main reason is that the three-dimensional geometry of stellarators makes the flux tube model...
Three dimensional magnetic equilibria are in general composed of nested flux surfaces, magnetic islands and chaotic field lines, although it is possible to design stellarator coil configurations that produce vacuum fields with nested flux surfaces (Pedersen, S. T. et al. 2016, Nature comm.). At finite $\beta$ however, currents self-generated by the plasma, such as diamagnetic, Pfirsch-Schlüter...
