Dimensionless analysis of H-mode plasmas for energy confinement and transport on EAST tokamak

This work presents an investigation of dimensionless parameter scaling laws for H-mode energy confinement and transport on experimental advanced superconducting tokamak (EAST), through dedicated experiments designed to isolate the individual effects of normalized plasma pressure ( β ) and collisionality ( ν * ). The β scaling experiment revealed a weak dependence of energy confinement time on β , resulting in a scaling exponent of α β ≈0.24 ± 0.20. This weak positive dependence, consistent with experiment observations and linear simulations, reflects an electrostatic turbulence dominated confinement regime in EAST H-mode plasmas. In contrast, a strong, negative dependence of confinement time on ν * was obtained, following the scaling Bτ E ∝ ν * − 0.71 ± 0.32 , indicating confinement improvement with decreasing ν * . Local transport analysis indicates that this strong ν * dependence is primarily associated with electron heat transport, while ion heat transport exhibits a comparatively weak sensitivity. While the linear instability spectrum is dominated by ion temperature gradient (ITG) modes across the explored parameter range, ν * strongly regulates turbulence characteristics relevant to electron heat transport, leading to a pronounced ν * dependence of global confinement. These distinct behaviors of electron and ion heat transport are associated with different physical mechanisms governing the confinement scaling with dimensionless parameters. The present results suggest that the confinement scaling exponents observed on EAST are closely tied to the turbulence regimes accessed in the dedicated β and ν * scans, providing physical insight into the differences with respect to global multi-machine scaling trends.