6月6日 五室第282期研讨

报告题目； Shafranov-Shift Destabilization of Ballooning-type Micro-instabilities

报 告 人： 简  翔

主 持 人： 何开洋

时    间：  2025年6月6日（星期五）下午14:00-15:00

地    点：  8-2楼224会议室

摘    要：

Contrary to common wisdom,we argue that the Shafranov shift is destabilizing for the ambient ballooning-type instabilities,which account for most of the transport flux in tokamak core plasmas. Higher Shafranov shift indeed reduces the magnetic drift frequency omega_d,i.e. improves the bad curvature mildly,around the outboard midplane. However,this improvement is limited to a very narrow spatial region while omega_d is increased over the remaining poloidal space. The eigenfunction averaged omega_d is effectively enhanced due to the finite mode width of the eigenfunction and is thus destabilizing to the ballooning-type mode,as demonstrated by gyrokinetic simulations with the CGYRO code using local Miller equilibrium geometry. The predicted nonlinear flux also increases with Shafranov shift,consistent with linear simulations. The reduced transport model TGLF can capture the physics reasonably well.

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