Studies of L-H Transition Thresholds in Electron Heated Regimes

We discuss transitions in collisionless, electron heated regimes where the electron-ion coupling is $ anomalous $, due to the fluctuation of $\left\langle \mathbf{E}\cdot\mathbf{J}\right\rangle$ work and explore new transition scenarios, characterized by the sensitivity of transition evolution to pre-existing L-mode profiles $ where\; turbulence\; driven\; shear\; flows\; are\; absent$. We have developed a reduced model that evolves the collisionally coupled electron and ion temperatures, density, turbulence intensity, and flow profiles. The power threshold minimum in density is revealed $ as\;a\;combined\;effect\;of\;the\; density\;dependence\;of\;collisionless\;electron-ion\;coupling\;and\;e-i\;heating\;mix$. To treat collisionless regimes, we have included anomalous power coupling between electrons and ions, using a recent theory of minimum enstrophy relation to model flow damping. Our preliminary results suggest that $ L\to H $ transition occurs as the endstate of an $electron-ion\;thermal\;coupling\;front$. Upon arriving at the edge, it impulsively raises $ T_i $ there, thus strengthening the diamagnetic electric field shear. This study highlights the importance of collisionless energy transfer process to transitions of regimes of ITER relevance.