Effect of Longitudinal Electric Field on Toroidal Diffusion

The driving toroidal electric field in Tokamaks is shown to lead to a significant pinching effect at low collision frequency. For ${\ensuremath{\beta}}_{\ensuremath{\theta}}=\frac{8\ensuremath{\pi}p}{B_{\ensuremath{\theta}}^{}{}_{}{}^{2}}<1$, where ${B}_{\ensuremath{\theta}}$ is the poloidal field, this pinching is more rapid than outward diffusion in the banana and plateau regimes of toroidal transport theory.