Negative-Triangularity Configuration on EAST: Analysis of engineering limitations on superconducting, D-shaped, target-diverted plasmas

Thermonuclear fusion is so named because of the high temperature that the majority of the fuel must maintain such that nuclei can overcome the electrostatic force, fuse, and produce energy. However, the ions and electrons (plasma) are so hot that any material used to confine them would be destroyed. To achieve confinement while maintaining the 50,000,000 K temperature needed for self-sustaining fusion, magnetic confinement is needed. As of 2019, the tokamak is the leading candidate for a practical fusion reactor. In recent years, tokamak research has repeatedly shown that the edge magneto-hydrodynamic stability is critical for handling the power to the walls and the divertor plates which is now and will most likely continue to be a limiting factor in the International Thermonuclear Experimental Reactor (ITER) and the DEMOnstration Power Station (DEMO). Recent experiments at Tokamak à Configuration Variable (TCV) and DIII-D have shown that a Negative-Triangularity Configuration (NTC) has a larger power handling area on the Low-Field-Side (LFS) divertor target plate and improved edge stability. However, there have been relatively few NTC experiments performed so far and none of them have been performed on a superconducting tokamak with shaping capabilities similar to ITER. To expand upon the previous experiments on TCV and DIII-D this thesis addresses an initial test of the NTC capability of the Experimental Advanced Superconducting Tokamak (EAST) which has achieved a ¡ 6 s ohmic discharge Upper Singular Null (USN) target-diverted plasma with a lower triangularity of X! ≤ -0.09