Tracking blobs in the turbulent edge plasma of a tokamak fusion device.

The analysis of turbulence in plasmas is fundamental in fusion research. Despite extensive progress in theoretical modeling in the past 15 years, we still lack a complete and consistent understanding of turbulence in magnetic confinement devices, such as tokamaks. Experimental studies are challenging due to the diverse processes that drive the high-speed dynamics of turbulent phenomena.

Existence of subsonic plasma sheaths.

The location of the plasma sheath edge, where quasineutrality is broken, is rigorously derived by using a kinetic description of the plasma. It is shown that sheaths can exist with arbitrarily small ion velocity at the sheath edge, thus violating the Bohm criterion, V(i)=c(s) at the sheath edge. Bohm's criterion is recovered in the case of large enough ion current through the wall, and it is found to be a reasonable approximation in floating potential conditions.