Neoclassical tearing modes

Tearing modes often limit the performance of toka-mak plasmas, because the magnetic islands which they generate lead to a loss of confinement, or even a disrup-tion. A particularly dangerous instability is the neoclassi-cal tearing mode, which can grow to a large amplitude because of the amplification effect that the bootstrap cur-rent has on an initial 'seed' magnetic island. This paper will address the mechanisms which dominate the neoclas-sical tearing mode evolution, and thereby identify possible control techniques.