Evidence for high-m secondary islands induced by large low-m islands in a tokamak plasma

Phys Rev Lett. 2005 Mar 4;94(8):085001. doi: 10.1103/PhysRevLett.94.085001. Epub 2005 Mar 3.

Abstract

Small-scale structures with high poloidal mode numbers (m=10-20) have been observed in the TEXTOR tokamak plasma with pulsed radar reflectometry and an electron cyclotron emission diagnostic, in conjunction with large 2/1 and 1/1 islands. The small islands have a peaked density profile, similar to that of the simultaneously observed large-scale 2/1 islands. This together with the observation that high-frequency density and temperature fluctuations are very pronounced near the X points of the large islands hints to a strongly perturbed magnetic topology around the X points.