Ion temperature gradient modes in toroidal helical systems

Linear properties of ion temperature gradient (ITG) modes in toroidal helical systems are studied. The real frequencies, growth rates, and eigenfunctions are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency I,lane. Based on a model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD); dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of VB-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare a ITG modes in helical systems with those in tokamaks.