2022/04/16 by Li, Jingchun, Liu, Songfen, Zhang, Yilong +2
#FOS: Physical sciences #Plasma Physics (physics.plasm-ph)
paper · doi:10.48550/arxiv.2204.07769
The drift wave in the presence of impurity ions was investigated numerically in reversed field pinch (RFP) plasmas, using the gyrokinetic integral eigenmode equation. It was found that in RFP plasmas with hollow density profiles, an increase in kθρs increases the growth rate of the ion temperature gradient (ITG). Comparing the results of regular and hollow plasma density profile shows that the ITG mode under the hollow density profile is much harder to be excited. For the impurities' effects, when the impurities' density gradient is opposite to the primary ions, namely when Lez is negative, impurities could enhance the instability. On the contrary, when Lez is positive, the instability is stabilized. Regarding the trapped electron mode (TEMs), the growth rate under the plasma with hollow density profile remained minor than that for the standard density gradient. There exists a threshold of Lez. When Lez is less than this value, impurity destabilizes TEMs, while as Lez is greater than this, impurity stabilizes TEMs. The effects of Lez on TEM also depend on both the plasma density gradient and the impurity species. In addition, the influence of collisionality on TEMs was also studied.