Control of neoclassical tearing modes by sawtooth control

Phys Rev Lett. 2002 Mar 11;88(10):105001. doi: 10.1103/PhysRevLett.88.105001. Epub 2002 Feb 25.

Abstract

The onset of a neoclassical tearing mode (NTM) depends on the existence of a large enough seed island. It is shown in the Joint European Torus that NTMs can be readily destabilized by long-period sawteeth, such as obtained by sawtooth stabilization from ion-cyclotron heating or current drive. This has important implications for burning plasma scenarios, as alpha particles strongly stabilize the sawteeth. It is also shown that, by adding heating and current drive just outside the inversion radius, sawteeth are destabilized, resulting in shorter sawtooth periods and larger beta values being obtained without NTMs.