抄録
This review intends to illustrate the physics processes that govern the various kinds of catastrophic events in toroidal plasmas. Varieties of abrupt changes of plasma parameters, e.g., disruptions, sawtooth, beta-collapse, etc., have been known in the history of plasma confinement research. They are called collapse events, and considered to be key issues because they might impose the achievable boundary of operation. Recent progresses of experiments (either in the achieved plasma parameters or in the accuracy of measurement) have illuminated the general view, that a sudden onset of the growth of the symmetry-breaking perturbations is the key to understand the collapse events. The growth of deformation does not proceed gradually associated with the variation of the plasma parameters; instead, the growth is “triggered”. In this review, overview of the collapse events is given first. Next it is illustrated that the trigger phenomena and accompanied large-scale deformation are the generic process in collapse events. Theoretical studies to understand the physics of collapse are then explained. It is also stressed that the studies of the physics of collapse events are exploring the frontiers of the modern physics.
