Edge flow measurements with Gundestrup probes

The ion current collected by a probe in a magnetized plasma is sensitive to the angle between its surface and the flow streamlines. This intuitive con cept is the basis of the Gundestrup probe, a polar array of planar collecto rs mounted around an insulating housing. Probe theory for measuring flows h as been developed on two fronts: Recent kinetic and fluid models, reviewed here, give similar predictions for the collected current within the range o f applicability of the model assumptions. A comparison with measurements by a rotating Mach probe in the CASTOR tokamak (Czech Academy of Sciences Tor us) [J. Stockel, J. Badalec, I. Duran , Plasma Phys. Controlled Fusion, 41, 577 (1999)] highlights the role of magnetization in ion collection at graz ing angles of incidence between the probe surface and the magnetic field li nes. (C) 2001 American Institute of Physics.