2024/04/03 by J. F. Parisi, J.F. Parisi, W. Guttenfelder +17 · 3 citations
Physics and Astronomy · #Magnetic confinement fusion research #Ionosphere and magnetosphere dynamics #Laser-Plasma Interactions and Diagnostics
paper · pdf · doi:10.1088/1741-4326/ad39fb
Abstract A theoretical model is presented that for the first time matches experimental measurements of the pedestal width-height Diallo scaling in the low-aspect-ratio high- β tokamak NSTX. Combining linear gyrokinetics with self-consistent pedestal equilibrium variation, kinetic-ballooning, rather than ideal-ballooning plasma instability, is shown to limit achievable confinement in spherical tokamak pedestals. Simulations are used to find the novel Gyrokinetic Critical Pedestal constraint, which determines the steepest pressure profile a pedestal can sustain subject to gyrokinetic instability. Gyrokinetic width-height scaling expressions for NSTX pedestals with varying density and temperature profiles are obtained. These scalings for STs depart significantly from that of conventional aspect ratio tokamaks.