【作者】 杨小庆；

【导师】 杨维紘； 王少杰；

【作者基本信息】 中国科学技术大学 ， 近代物理系， 2014， 博士

【摘要】 撕裂模是托卡马克运行过程中最危险的磁流体不稳定性之一,它可以改变磁场的拓扑结构破坏等离子体平衡,严重时可能导致托卡马克放电终止,造成严重后果。为保证托卡马克正常运行,必须抑制这种不稳定性。到目前为止实验上已经采用了很多方法抑制撕裂模,但是这些方法在技术上都有一定的难度。一种简单易行的办法是通过加入随时间振荡的调制电流抑制撕裂模。在等离子体平衡电流的基础上加入随时间振荡的调制电流,有理面的位置会随时间振荡。如果有理面位置的振幅足够大且振荡频率高于撕裂模的线性增长率,撕裂模可以被有效抑制。通过振荡有理面抑制撕裂模所需要的低杂波电流驱动的功率和通常的通过电子回旋波电流驱动抑制撕裂模所需的功率相差不多。随着托卡马克参数的提高,新经典效应对电流调制稳定撕裂模的效率有着不可忽略的作用。新经典电阻效应降低了等离子体内部电流扩散时间,使调制电流更易于穿透到等离子体内部。在振荡环电压的作用下,等离子体以调制的Ware-pinch速度随时间径向振荡。这些新经典效应提高了电流调制稳定撕裂模的效率。更多还原

【Abstract】 Tearing mode, which is one of the most dangerous magnetohydrodynamic in-stabilities in tokamak, can change the topology of the magnetic field, destroy the equilibrium of plasma, and in extreme cases the tearing mode can terminate the plasma discharge and lead to grave consequences. Therefore, to ensure the normal operation of a tokamak,the tearing mode must be stabilized effectively. Various methods have been used to stabilize the tearing mode, but these methods have some technical difficulties. An alternative way to control the tearing mode is to make the resonant surface oscillate with time by modulating the plasma current. With a modulation current which oscillates with time added on the equilibrium current, the radial position of the resonant surface can be oscillated. Tearing modes can be stabilized, if the frequency of the oscillation is higher than the clas-sical growth rate of the tearing mode, and the amplitude of the resonant surface oscillation is large enough. The power needed for the lower hybrid current drive to oscillate the resonant surface and suppress the tearing mode is comparable to the conventional method of tearing mode suppression by the electron cyclotron wave current drive. As the parameters of tokamak improved, the neoclassical effects play important roles on the stabilization of tearing modes by current modulation. Neoclassical effects enhance the resistivity and reduce the resistive diffusion time of the modulation current. Therefore, the oscillating current can penetrate deeper into the plasma. With an oscillating loop voltage, the plasma oscillates radially in the Ware-pinch velocity. These neoclassical effects improve the efficiency of tearing mode stabilization by the current modulation.更多还原