The disparate impact of the ion temperature gradient and the density gradient on edge transport and the low-high transition in tokamaks

Kleva, Robert G.; Guzdar, Parvez N.
March 2009
Physics of Plasmas;Mar2009, Vol. 16 Issue 3, p032305
Academic Journal
Steepening of the ion temperature gradient in nonlinear fluid simulations of the edge region of a tokamak plasma causes a rapid degradation in confinement. As the density gradient steepens, there is a continuous improvement in confinement analogous to the low (L) to high (H) transition observed in tokamaks. In contrast, as the ion temperature gradient steepens, there is a rapid increase in the particle and energy fluxes and no L-H transition. For a given pressure gradient, confinement always improves when more of the pressure gradient arises from the density gradient, and less of the pressure gradient arises from the ion temperature gradient.


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