Research On The Influence Of Plasma Current Modulation On Tearing Mode Instability In The J-TEXT Tokamak

The MHD(Magneto-Hydrodynamic) instabilities are very common in Tokamak experiments, which will lead to the confinement degeneration and even plasma disruption. Therefore, suppressing the MHD instabilities is a key issue in tokamak research and future fusion reactors. There is a new method put forward to suppress the MHD instability, which is the plasma current modulation(PCM). The toroidal current is modulated by programming the Ohmic heating field and it is superimposed on the plasma equilibrium current. With the proper parameters, PCM can suppress the MHD perturbations effectively. Motivated by avoiding MHD instabilities, experiments aiming for investigating the influence of plasma current modulation(PCM) on MHD instabilities are carried out in J-TEXT.The first chapter introduced the MHD instabilities. Besides, the fundamental state about the experimental methods in order to suppress MHD instabilities and the systematic overview of PCM experimental research on different tokamaks are also described in this chapter. In the second chapter, the physical theory of MHD instabilities and the physical model of PCM are presented.After a brief description of the experimental set-up, the diagnostic equipments needed in PCM experiments, such as the Mirnov probe arrays, ECE, POLARIS, are also introduced in the third chapter. The experimental results are presented in fourth chapter, including how the amplitude, frequency and waveform of modulated current affect the MHD instabilities suppression in PCM experiments. In fifth chapter, the summaries and discussions are given.