  The presence of current sheet instabilities, such as the tearing mode
instability, are needed to account for the observed rate of energy release in
solar flares. Insights into these current sheet dynamics can be revealed by the
behaviour of flare ribbon substructure, as magnetic reconnection accelerates
particles down newly reconnected field lines into the chromosphere to mark the
flare footpoints. Behaviour in the ribbons can therefore be used to probe
processes occurring in the current sheet.
  In this study, we use high-cadence (1.7 s) IRIS Slit Jaw Imager observations
to probe for the growth and evolution of key spatial scales along the flare
ribbons - resulting from dynamics across the current sheet of a small solar
flare on December 6th 2016. Combining analysis of spatial scale growth with Si
IV non-thermal velocities, we piece together a timeline of flare onset for this
confined event, and provide evidence of the tearing-mode instability triggering
a cascade and inverse cascade towards a power spectrum consistent with plasma
turbulence.
