Multimachine Database Study of I-Mode Core Confinement and Edge Gradients

A multi-machine database for the study of I-mode performance has been compiled, consisting of over 100 time-averaged parameters across steady-state time slices from DIII-D, ASDEX-Upgrade and Alcator C-Mod, including previously unanalyzed discharges. I-mode is an ELM-free enhanced confinement regime with L-mode-like particle transport, though no multi-machine confinement scalings such as those for L- and H-mode have yet been produced. Stemming from the 2022 DOE Joint Research Target, with some AUG and many C-Mod slices added, the database will be used to close this knowledge gap. In-device and cross-device dimensional τE scalings will be derived and compared with literature. Other key parameters for predicting I-mode performance are edge gradients and pedestal pressures. Fits for each of these will be derived in terms of dimensional parameters and compared to literature, with particular attention given to differences in edge behavior between I-modes and high power L-modes. With an improved understanding of core and edge performance we can improve confidence in projections of high-performance I-mode operation in future devices.