Integrated analysis of high-β_N double transport barriers scenario on HL-2A

Tokamak is considered as the most promising experimental setup for achieving controllable nuclear fusion requirements. The parameter beta(N) is an important parameter for tokamak devices: high beta(N) benefits not only to plasma fusion but also to the enhancement of fusion reaction efficiency and the facilitation of steady-state operation. The HL-2A tokamak device has achieved stable plasma beta(N) with exceeding than 2.5 through neutral beam injection heating, and transiently reached beta(N) = 3.05, with a normalized density (n(e,1)/n(e,G)) of about 0.6, stored energy (W-E) of around 46 kJ, and confinement improvement factor (H-98) of about 1.65. In this work, the integrated simulation platform OMFIT is used to analyze the plasma at beta(N) = 2.83 and beta(N) = 3.05, and the obtained W-E, n(e,1)/n(e,G), H-98,H- beta(N), etc. are consistent with the experimental parameters. The bootstrap current (f(BS)) can reach to and. At both of the above moments, there are ion temperature double transport barrier (DTB) generated by the coexistence of internal transport barrier (ITB) and edge transport barrier (ETB), while high beta(N) is usually related to DTB. In addition, the formation of ion temperature ITB in the HL-2A device is further analyzed, which is attributed to the dominance of turbulent transport in plasma transport, the suppression of turbulent transport in the core by fast ions and E x B shear, and the resulting improvement in confinement, thereby ultimately leading to the formation of ion temperature ITB. The ITB of ion temperature and the ETB of H-mode synergistically contribute to the creation of high beta(N) plasma.