  Solar flares are complex phenomena emitting all types of electromagnetic
radiation, and accelerating particles on timescales of minutes, converting
magnetic energy to thermal, radiative, and kinetic energy through magnetic
reconnections. As a result, local plasma can be heated to temperatures in
excess of 20 MK. During the soft X-ray (SXR) solar flare peak, the elemental
abundance of low first-ionization potential (FIP) elements are typically
observed to be depleted from coronal values. We explored the abundance
variations using disk-integrated solar spectra from the Miniature X-ray Solar
Spectrometer CubeSat-1 (MinXSS-1). MinXSS-1 is sensitive to the 1-12 keV energy
range with an effective 0.25 keV full-width at half-maximum (FWHM) resolution
at 5.9 keV. During the year-long mission of MinXSS-1, between May 2016 - May
2017, 21 flares with intermittent data downlinks were observed ranging from C
to M class. We examine the time evolution of temperature, volume emission
measure, and elemental abundances of Fe, Ca, Si, S, and Ar with CHIANTI
spectral models near the peak SXR emission times observed in the MinXSS-1 data.
We determined the average absolute abundance of A(Fe) = 7.81, A(Ca) = 6.84,
A(S) = 7.28, A(Si) = 7.90, and A(Ar) = 6.56. These abundances are depleted from
coronal values during the SXR peak compared to non-flaring times. The elemental
abundance values that are depleted from their coronal values are consistent
with the process of chromospheric evaporation, in which the lower atmospheric
plasma fills the coronal loops.
