In most present-day tokamaks, the majority of the heating power comes from sources such as neutral-beam injection (NBI) and other types of auxiliary heating which allow for the transfer of energy to the plasma by a small population of externally introduced fast particles. The behavior of the fast ions is important for the overall plasma dynamics, and understanding their influence is vital for the success of any future magnetic confinement devices. In the TUMAN-3M tokamak, it has been noted that the loss of fast particles during NBI can lead to dramatic changes in the rotation velocity profiles, as they are responsible for the negative radial electric field on the periphery.
