Energy confinement scaling in the NCST spherical tokamak

Energy confinement time τE and its scaling law in the NanChang Spherical Tokamak (NCST) are investigated based on experimental data from NCST campaigns, with a focus on their dependence on plasma current (IP), toroidal magnetic field (BT), and electron density (ne). Multivariate fitting results indicate that τE exhibits a weak nonlinear dependence on BT and a weaker dependence on IP, while its dependence on ne is extremely weak. Single-parameter scanning results further confirm the key dependencies on IP and BT. These findings contribute to the broader physics understanding of confinement in low-aspect-ratio tokamaks and inform the design of future spherical tokamaks such as the NCST-U.