Plasmoid motion in helical plasmas

In order to explain the difference between the motion of plasmoids created by pellet injection in tokamak and helical plasmas, magnetohydrodynamic (MHD) simulations including ablation processes have been performed in tokamak and Large Helical Device (LHD) plasmas. In the LHD, plasmoid motion depends on the initial location of the plasmoid, whereas in a tokamak, the plasmoid always drifts in the direction opposite to that of the curvature vector. It is verified that there are two main forces acting on the plasmoid, and the connection length determines the dominant force. (author)