Investigating the density evolution after the L-H transition in Deuterium and Hydrogen plasmas

In tokamaks to achieve the high confinement (H-mode) necessary for beneficial fusion conditions, turbulent transport at the plasma edge is suppressed. This bifurcation from low (L-mode) to H-mode confinement results in the slow build up of steep temperature and density gradients at the plasma edge. In this poster we will be comparing the electron density evolution for hydrogen and deuterium at low and high starting electron density. We observe that at low density that density evolution at the plasma edge with respect to time is linear, whereas at higher density this evolution is non-linear. The electron density increases faster in the hydrogen plasma at low density, but saturates at a lower value than the deuterium plasma. We will extract the transport coefficients by matching spatial as well as temporal evolution of the electron density profile for all 4 experiments and compare these to expected transport scalings.