Internal Transport Barrier
No generally accepted definition for Internal Transport Barriers (ITBs) exists. Vaguely speaking, a radially localized reduction of transport is meant. Factors contributing to the creation of such barriers include: [1]
- Power deposited inside the magnetic surface, and/or pressure gradients
- Magnetic shear and the shape of the profile of the rotational transform
- MHD activity
- Momentum torques
Physical mechanism
The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood. Probably, it is related to the mechanism for the formation of the H-mode barrier, involving turbulence suppression by sheared flows, possibly associated with rational magnetic surfaces.