Advanced tokamak scenarios, ITB dynamics and instabilities in fusion plasmas

For a self-sustained fusion power plant, self-generated non-inductive current drive has to be maintained by bootstrap current that is mostly due to very high plasma pressure. Plasma with central reverse magnetic shear has peaked current density near the shear reversal position. Such a configuration has a steep pressure profile that can lead to E X B shear flows that can reduce or suppress the turbulence driven by the free energy coming from the gradient in the profiles. These internal transport barriers(ITBs) help improve confinement but need to be controlled to prevent instabilities and clean the ash. To both maintain the steep profiles and to relax them, auxiliary heating like neutral beams and radio frequency heating as well as pellet can be used as control tools. Position, amplitude and deposition width have important roles. Optimizing these parameters ITBs can be controlled in fusion devices. Demonstration scenarios in current and future devices will be investigated.