SCRAPE-OFF LAYER TURBULENCE THEORY AND SIMULATIONS

Significant investigations in the area of scrape-off layer (SOL) turbu lence theory and simulations are reviewed. The paper begins with descr iption and derivation of the various models investigating specific lin ear modes as well as a discussion of the regions of validity. Special attention is given to various low-frequency electromagnetic drift-type s modes in an x-point divertor geometry, which are generally believed to be relevant under normal operating conditions for current and futur e large fusion devices. The anomalous transport from simulations and f rom mixing length estimates are discussed and compared with results in fered from experiments. Studies of mechanisms for the L-H transition d ue to turbulent transport in the SOL, and its impact on the II-mode po wer threshold, are also surveyed.