Core temperature evolution in HBT-EP during L- to biased H-mode transitions

A robust method of accessing the biased H-mode on HBT-EP was recently demonstrated [1]. From these studies it is known that while the pedestal temperature increases, the core temperature does not upon entering the biased H-mode [1], and this observation is consistent with other small tokamaks. This poster extends this analysis by exploring core temperature evolution during L- to biased H-mode (and the reverse) transitions using a tangential extreme ultraviolet (EUV) sensor array. Transitions into and out of the biased H-mode are controlled by varying the strength of a bias probe’s voltage as well as when it is tuned on/off during a plasma cycle. Comparisons of the temporal core temperature measurements and other plasma parameters between the H- and L-mode cases as well as during transitions are discussed. A survey of measurements of profile evolution and evolution time-scales will also be presented.

[1] I. Stewart et al 2021 Phys. Plasmas 28, 052506.