Magnetic compressibility and ion-temperature-gradient-driven microinstabilities in magnetically confined plasmas. (2nd July 2015)

• Record Type: Journal Article
• Authors: Zocco, A; Helander, P; Connor, J W
• Is Part Of: Plasma physics and controlled fusion. Volume 57:Number 8(2015:Aug.)
• Publication Date: 2015-07-02
• Subjects: electromagnetic ITG -- fusion -- turbulence; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/0741-3335/57/8/085003
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: The electromagnetic theory of the strongly driven ion-temperature-gradient (ITG) instability in magnetically confined toroidal plasmas is developed. Stabilizing and destabilizing effects are identified, and a critical β e (the ratio of the electron to magnetic pressure) for stabilization of the toroidal branch of the mode is calculated for magnetic equilibria independent of the coordinate along the magnetic field. Its scaling is β e ∼ L Te / R, where L Te is the characteristic electron temperature gradient length, and R the major radius of the torus. We conjecture that a fast particle population can cause a similar stabilization due to its contribution to the equilibrium pressure gradient. For sheared equilibria, the boundary of marginal stability of the electromagnetic correction to the electrostatic mode is also given. For a general magnetic equilibrium, we find a critical length (for electromagnetic stabilization) of the extent of the unfavourable curvature along the magnetic field. This is a decreasing function of the local magnetic shear.