Effect of magnetic perturbations on divertor scrape-off width

A general method is developed for calculating the width, due to magnetic perturbations, of the scrape-off layer of a tokamak with a divertor. The method, which assumes the plasma particles are tied to the field lines, should provide a good estimate provided the predicted width is large compared to that given by particle diffusion or finite particle drift orbit effects. The general theory is applied to a simple analytic model of a divertor to indicate the expected magnitude of the scrape-off layer thickness.