High and very high modes from energy, particle, and momentum transport models

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Abstract
Time‐dependent simulations of energy, particle, and momentum transport are presented, which show improved confinement similar to the high mode (H mode). The transport model incorporates the suppression of turbulence by sheared flows, which are self‐consistently calculated. Constraints on the turbulence model from the time evolution of the temperature, density, and velocity profiles are discussed. A regime similar to the very high confinement mode (VH mode) is found to result at higher heating power due to an increase in the width of the transport barrier. Coneutral beam injection lowers the power required for VH mode substantially due to the toroidal rotation shear. The possible role of edge momentum sources such as ion orbit loss is considered, and a comparison between biased probe‐induced and heating‐induced H modes is made.