This module is an implementation of the model by Franco Porcelli
to compute the conditions needed to trigger
a sawtooth crash in tokamak plasmas.
It is assumed, in the Porcelli model, that each sawtooth crash is triggered by the onset of an $m=1$ mode. The macroscopic drive for this mode is associated with an effective potential energy functional, that includes effects from toroidicity and plasma shaping and kinetic effects arising from trapped thermal particles and fast ions, respectively.