Session KP01 - Poster Session III.
POSTER session, Tuesday afternoon, March 23
Exhibit Hall, GWCC
Neoclassical tearing modes (NTM) have been observed on the DIII-D tokamak to be triggered by the magnetic perturbation of a sawtooth crash and to inversely scale with the Lundquist number.(R. J. LaHaye and O. Sauter, Nuclear Fusion, Vol. 38, (1998), 1.) Since NTMs require a seed island for excitation, secondary islands that are driven by the coupling of poloidal harmonics in toroidal geometry to the unstable internal resistive kink and its harmonics are presumed to be responsible for producing an island of sufficient width to exceed the NTM threshold. The physics of such secondary island formation is a complicated forced reconnection problem, where the amplitude of the secondary islands is determined by layer physics.(C.C. Hegna and J.D. Callen, CPTC Report 98-5) NTM simulation results will be presented and compared with analytic theory for DIII-D shot 86144 based on the NIMROD code. Simulation results of the secondary island formation will also be presented and compared with scalings for both the Lundquist number and differential rotation.