  An X1.6 flare occurred in AR 12192 on 2014 October 22 at 14:02 UT and was
observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel which
produces a white light (WL) flare with continuum enhancement and a hard X-ray
(HXR) peak. Taking advantage of the spectroscopic observations of IRIS and
Hinode/EIS, we measure the temporal variation of the plasma properties in the
bright kernel in the chromosphere and corona. We found that explosive
evaporation was observed when the WL emission occurred, even though the
intensity enhancement in hotter lines is quite weak. The temporal correlation
of the WL emission, HXR peak, and evaporation flows indicate that the WL
emission was produced by accelerated electrons. To understand the white light
emission process, we calculated the energy flux deposited by non- thermal
electrons (observed by RHESSI) and compared it to the dissipated energy
estimated from a chromospheric line (Mg II triplet) observed by IRIS. The
deposited energy flux from the non-thermal electrons is about 3 ~ 7.7 X 10^(10)
erg cm^(-2) s^(-1) for a given low energy cut-off of 30 ~ 40 keV, assuming the
thick target model. The energy flux estimated from the temperature changes in
the chromosphere measured using the Mg II subordinate line is about 4.6 - 6.7 X
10(9) erg cm^(-2) s^(-1): ~6-22% of the deposited energy. This comparison of
estimated energy fluxes implies that the continuum enhancement was directly
produced by the non-thermal electrons.
