title: Simultaneous measurements of the parallel and perpendicular ion temperature with a pinhole probe in the scrape-off-layer of the tokamak ISTTOK.
abstract: A pinhole probe (PHP) for the simultaneous measurement of the parallel, T(parallel), and perpendicular, T(perpendicular), ion temperature has been designed and tested in the scrape-off-layer (SOL) plasma of the tokamak ISTTOK. The PHP consists of a tunnel immersed into the plasma parallel to magnetic field and an ion collector. One end of the tunnel is covered with a thin foil that has a pinhole sampling ions from the plasma. The other end of the tunnel (close to the negatively biased collector) is covered with a fine-mesh screen. The possibility of performing an analytical description of the PHP current-to-voltage characteristics obtained on the collector when biasing the tunnel simplifies the interpretation of the results. The PHP operation has been previously tested in T(parallel), T(perpendicular) measurements in low temperature weekly magnetized plasma [H. Mase, T. Honzava, and G. Miyamoto, J. Appl. Phys. 49(10), 5171 (1978)]. In this paper, the PHP operation in the SOL of the tokamak ISTTOK is described, and the first results of T(parallel) and T(perpendicular) measurements are presented. The obtained results demonstrate strong (~30%) variation of T(parallel) and T(perpendicular) on a time scale of 0.5 ms, and general predominance of T(parallel) > T(perpendicular) anisotropy (T(parallel mean)/T(perpendicular mean) ~ 1.5) during plasma shot.
authors.affiliation: Associação EURATOM/IST, Instituto de Plasma e Fusão Nuclear-Laboratório Associado, Instituto Superior Técnico, Universidade Técnica Lisboa, 1049-001 Lisboa, Portugal.
authors.forename: I S
authors.initials: IS
authors.lastname: Nedzelskiy
authors.forename: C
authors.initials: C
authors.lastname: Silva
authors.forename: P
authors.initials: P
authors.lastname: Duarte
authors.forename: H
authors.initials: H
authors.lastname: Fernandes