Pinch Effect for Trapped Particles in a Tokamak

Abstract

Conservation of canonical angular momentum is shown to require that all trapped particles drift towards the magnetic axis with velocity $\frac{c{E}_{\varphi }}{B_{\theta }}$ ($E_{\varphi }$ is the toroidal electric field; $B_{\theta }$ the poloidal magnetic field). This property, plus an amplification process for the number of trapped particles, will explain the relaxation oscillations which occur for $q<\mathrm{}3\mathrm{}$. In addition, there is experimental evidence that it is an important contribution to the good containment when $q>\mathrm{}3\mathrm{}$.