We use the Chandra X-ray Observatory to analyze interactions of the blast wave and the inhomogeneous interstellar medium on the western limb of the Cygnus Loop supernova remnant .
This field of view includes an initial interaction between the blast wave and a large cloud , as well as the encounter of the shock front and the shell that surrounds the cavity of the supernova progenitor .
Uniquely , the X-rays directly trace the shock front in the dense cloud , where we measure temperature kT = 0.03 keV .
We find kT \approx 0.2 keV in regions where reflected shocks further heat previously-shocked material .
Applying one-dimensional models to these interactions , we determine the original blast wave velocity v _ { bw } \approx 330 { km s ^ { -1 } } in the ambient medium .
We do not detect strong evidence for instabilities or non-equilibrium conditions on the arcsecond scales we resolve .
These sensitive , high-resolution data indicate no exceptional abundance variations in this region of the Cygnus Loop .