FREEZING IN OF A MAGNETIC-FIELD IN A KINETIC DESCRIPTION OF A COLLISIONLESS PLASMA

The reason for the freezing in of a magnetic field and the reasons for the disruption of this effect in a collisionless plasma are analyzed. The concept of a ''freezing-in preserver'' is introduced. In a tokama k, the role of this preserver may be played by untrapped electrons, wh ich are not at resonance with turbulence and which thus execute an int egrable motion. As a result, the poloidal magnetic field is frozen in the toroidal field. Under these conditions the diffusion of particles and heat may be governed by turbulence, in agreement with experiment.