Characterization of edge plasma and turbulence in the Phaedrus-T tokamak

Abstract

A portable fluctuation diagnostic facility, equipped with a fast reciprocating Langmuir probe array, has participated in a collaborative measurements of edge turbulence and transport in the edge plasma of the Phaedrus-T tokamak. As is typical of many other ohmically heated tokamak plasmas, it is found that fluctuation driven particle flux plays an important role in the oarticle transport and that the normalized fluctuation level has ordering e φ ˜ p / T e > n ˜ / n > T ˜ e / T e and e φ ˜ p / T e > p ˜ / p where p=nTe. A comparison is made of Langmuir probe measurements obtained from probe tips of different construction to quantify the poloidal asymmetry in equilibrium plasma parameters observed in the scrape-off layer. Near the last closed flux surface, a shear layer marked by changes in several fluctuation properties was observed.