Development of Electron Temperature Gradient Transport Model for Tokamak Plasmas

T. Rafiq, J. Weiland, E. Schuster, A. Pankin

Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)

Pittsburgh, PA, USA (Remote), November 8-12, 2021

Progress in the development of a new model for the electron-temperature-gradient (ETG) modes in tokamaks is presented for a general geometry. The ETG modes can be unstable in conventional and low-aspect ratio tokamaks, resulting in turbulence-driven electron thermal transport. Burning plasma discharges, where collisions with fast alpha particles primarily heat electrons, would also benefit from a better understanding of ETG turbulence and transport. This new model will replace an old model in the Multi-Mode Module that employs empirical coefficients for ETG-driven transport. The new model includes new significant plasma-parameter dependences but does not contain empirical coefficients. Although the ETG modes at the electron gyroradius scale are essentially electrostatic, electromagnetic effects in high beta tokamak plasmas must be taken into account. A system of equations is presented governing the dynamics of low-frequency short-wavelength electromagnetic ETG-driven drift modes in the presence of density/temperature/magnetic field gradients, curvature, finite beta, collisionality, and reverse/low magnetic shear. Non-adiabatic ion effects, including E×B and polarization drifts, are taken into account without including ion-temperature-gradient mode fluctuations.

*Supported by the US DOE under DE-SC0021385, DE-SC0013977, and DE-SC0020251.