Kinetic solution to the Mach probe problem in transversely flowing strongly magnetized plasmas

The kinetic equation governing a strongly magnetized transverse plasma flow past a convex ion-collecting object is solved numerically for arbitrary ion to electron temperature ratio τ. The approximation of isothermal ions adopted in a recent fluid treatment of the same plasma model [ I. H. Hutchinson Phys. Rev. Lett. 101 035004 (2008)] is shown to have no more than a small quantitative effect on the solution. In particular, the ion flux density to an elementary portion of the object still only depends on the local surface orientation. We rigorously show that the solution can be condensed in a single “calibration factor” M_c, function of τ only, enabling Mach probe measurements of parallel and perpendicular flows by probing flux ratios at two different angles in the plane of flow and magnetic field.