  The ion temperature during magnetic reconnections measured along the
direction of the magnetic field at the MST Reverse Field Pinch has not yet
received a satisfactory theoretical explanation. In this work we argue that it
is consistent with a picture of ion energization by the parallel electric
fields generated by the plasma during reconnection, and thermalization due to
the chaotic ion dynamics. Three possible sources of randomness are pointed out:
particle motion along static stochastic magnetic field lines, breakup of the
adiabatic ion dynamics caused by the strong gradient nonlinearity of the
magnetic field, parallel acceleration along stochastic time-dependent electric
fields. The three mechanisms are likely operative simultaneously; regardless
the specific mechanism active, the correct scaling laws with ion parameters are
recovered. Furthermore, we argue that quantitative agreement can be obtained by
feeding the model with realistic values for the plasma conditions.
