Study On Plasma ITG And TEM Drift Wave In Tokamak Core

In magnetic confinement fusion devices, the plasma transport processes directlydetermine the constraint performance of the devices. Experimental results on themeasurement of unusually large transport coefficients of ions and electrons show that particletransport of Tokamak plasma is an anomalous transport. In generally, the core plasmatransport is mainly driven by ITG (ion temperature gradient mode) and TEM (trappedelectron mode). Based on the Weiland model, from the perspective of the two fluid equationswith the collision term, the dispersion relation of the ion temperature gradient mode(ITG) andthe trapped electron mode (TEM) are obtained and the growth rate of these two unstable modein HL-2A core plasma without impurity ion is calculated when0.1<k y ρsH<2.0.The results of the growth rate of ITG and TEM in core plasma without impurity ionshow that: the growth rates of these two unstable mode both are closely related to thewavelength of perturbations and both of them are in threshold model. However, ITG is drivenonly by the ion temperature gradient while TEM is driven by both electron density gradientand temperature gradient. The density gradient has a stabilizing impact on ITG but adestabilizing impact on TEM. The growth rate of ITG increases with ion temperature gradientwhile the growth rate of TEM decreases at first and then increases with electron temperaturegradient.Furthermore, the effects of the radial coordinate, the magnetic shear and the collision onthe growth rates of these two modes is analyzed. The computation results indicate that thegrowth rate of both modes increase with the radial coordinate while TEM increases muchmore quickly. The effect of collision to the ITG and TEM depends on both temperaturegradient and density gradient. The collision have a slight stabilizing impact on ITG in lowertemperature gradient. The collision can destabilize TEM in lower density gradient. In addition,if the density gradient is much higher, then the collision has a stabilizing effect on TEM in both lower and higher temperature gradient but a destabilizing effect in other temperaturegradient. The magnetic shear can destabilize ITG while it’s impact on TEM depends ontemperature gradient. The magnetic shear can stabilize TEM in low temperature gradient butdestabilize TEM in high temperature gradient.