Nonlocal transport in the scrape-off plasma in tokamak

Even when the hydrodynamic approximation is satisfied on average, i.e., when the mean free path is much less than the characteristic longitudinal gradients, the expressions for the classical heat conductivity and viscosity coefficients turn out to be overestimated. This is due to the fact that the hydrodynamic heat and momentum fluxes are determined by the tail of the distribution function and become essentially nonlocal by nature. In the paper the Grad method is used to determine the transport structure. The integral expressions for the longitudinal heat and momentum fluxes are obtained