Ion temperature gradient modes in toroidal helical systems

Linear properties of ion temperature gradient (ITG) modes in toroidal helic al systems are studied. The real frequencies, growth rates, and eigenfuncti ons are obtained for both stable and unstable cases by solving a kinetic in tegral equation with proper analytic continuation performed in the complex frequency I,lane. Based on a model magnetic configuration for toroidal heli cal systems like the Large Helical Device (LHD); dependences of the ITG mod e properties on various plasma equilibrium parameters are investigated. Par ticularly, relative effects of VB-curvature drifts driven by the toroidicit y and by the helical ripples are examined in order to compare a ITG modes i n helical systems with those in tokamaks.