  In tokamak disruptions where the magnetic connection length becomes
comparable to or even shorter than the plasma mean-free-path, parallel
transport can dominate the energy loss and the thermal quench of the core
plasma goes through four phases (stages) that have distinct temperature ranges
and durations. The main temperature drop occurs while the core plasma remains
nearly collisionless, with the parallel electron temperature $T_{e\parallel}$
dropping in time $t$ as $T_{e\parallel}\propto t^{-2}$ and a cooling time that
scales with the ion sound wave transit time over the length of the open
magnetic field line. These surprising physics scalings are the result of
effective suppression of parallel electron thermal conduction in an otherwise
bounded collisionless plasma, which is fundamentally different from what are
known to date on electron thermal conduction along the magnetic field in a
nearly collisionless plasma.
