High resolution X-ray spectra extracted from 17 bright, narrow regions of
Cas A provide unique insights into their kinematics and plasma state. From
the dominant emission lines of H- and He-like silicon and sulfur we derive
accurate Doppler shifts in the range -2500 to +4000 km/s which agree well
with transverse-velocity measurements (DeLaney 2004.) Plasma diagnostics
of these regions indicate temperatures largely of order 1 keV with some
above 3 keV. Using as well the non-dispersed zeroth-order data, we
determine NEI model parameters for the regions and consider them in the
context of an O-rich reverse-shocked ejecta model (Laming & Hwang 2003.)
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