Gyrokinetic study of impurity mode in reversed-field pinch

¹ Department of Physics, Nankai University - Tianjin 300071, PRC
² Consorzio RFX, Associazione Euratom-ENEA sulla fusione - Corso Stati Uniti 4, Padova 35127, Italy, EU
³ Institute for Fusion Theory and Simulation, Zhejiang University - Hangzhou 310027, PRC
⁴ Southwestern Institute of Physics - Chengdu 610041, PRC

^a lsfnku@nankai.edu.cn

Received: 20 October 2011
Accepted: 30 January 2012

Abstract

The impurity mode in toroidal reversed-field pinch (RFP) plasma is studied, using the gyrokinetic integral equation. A second species of ions with density gradient opposite to the primary ion and electron density gradients is considered. The effects of impurity charge concentration, ratio of electron density gradient scale length to impurity density gradient scale length, finite Larmor radius, safety factor, magnetic shear, ion as well as electron density gradient scale lengths on the impurity mode are investigated in detail. It is demonstrated that the impurity mode in RFP plasmas is relatively more difficult to be excited than that in tokamak plasmas under similar geometry when the density profile is flat, whereas it turns out to be easier when the density profile is rather peaked.