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.