Plasma collection by an obstacle

Abstract

Plasma flow to an obstacle is examined using the two-fluid equations. In this model the obstacle is assumed to be a two-dimensional strip that extends to infinity in they direction (slab g~ometry?. An obstacle inserted into a magnetized plasma will cast a "shadow" along the m~gnetlc field hn~s. The natural collection length of such an obstacle is a measure of the length of Its sh_adow. This study shows that in a typical fusion tokamak, where c,!Oc;d< 1 (fie;• cs are the Ion cyclotron frequency and the ion acoustic speed, respectively, dis the half-width of the ~trip), the particle collec_tion length of an obstacle can be approximated as L 11 = 0.23c 5