The Bragg Crystal Spectrometer (BCS) is one of the instruments which makes up
the scientific payload of the Yohkoh mission. The spectrometer employs four
bent germanium crystals, views the whole Sun , and observes the resonance line
complexes of H-like FeXXVI, CaXIX, and SXV in four narrow wavelength ranges
with a resolving power (lambda/delta-lambda) of between 3000 and 6000.
The spectrometer has approaching 10 times better sensitivity than that of
previous instruments thus permitting a time resolution of better that 1 s to
be achieved. The principal aim is the measurement of the properties of the
10 to 50 million K plasma created in solar flares with special emphasis
on the heating and dynamics of the plasma during the impulsive phase.