Non-perturbative models of intermittency in edge turbulence

A theory of the probability distribution function (PDF) tails of the blob density in plasma edge turbulence is provided. A simplified model of the fast convective radial transport is used. The theoretically predicted PDF tails corroborate earlier measurements of edge transport, further confirming the strongly non-Gaussian feature of edge transport. It is found that increasing the cross sectional spatial scale length ($L_x$ and $L_y$) of the blob results in larger transport whereas increasing the toroidal scale length ($L_z$) decreases the PDF. The results imply that the PDF decreases for larger blob speed $v_b$.