  The cause of excess spectral line broadening (non-thermal velocity) is not
definitively known, but given its rise before and during flaring, the causal
processes hold clues to understanding the triggers for the onset of
reconnection and the release of free magnetic energy from the coronal magnetic
field. A comparison of data during a 9-hour period from the extreme ultraviolet
(EUV) Imaging Spectrometer (EIS) on the Hinode spacecraft - at a 3-minute
cadence - and non-linear force-free field (NLFFF) extrapolations performed on
Helioseismic and Magnetic Imager (HMI) magnetograms - at a 12-minute cadence -
shows an inverse relationship between non-thermal velocity and free magnetic
energy on short timescales during two X-class solar flares on 6 September 2017.
Analysis of these results supports suggestions that unresolved Doppler flows do
not solely cause non-thermal broadening and instead other mechanisms like
Alfv\'en wave propagation and isotropic turbulence have a greater influence.
