  The Cygnus Loop is interacting with a protrusion of the cavity wall in its
eastern edge (the XA region), where the X-ray emission is very bright. The
complexity of the environment and the non-linear physical processes of the
shock-cloud interaction make the origin of the X-ray emission still not well
understood. Our purpose is to understand the physical origin of the X-ray
emission in the XA region, addressing, in particular, the role of thermal
conduction in the interaction process. We analyzed two XMM-Newton data sets,
performing image analysis and spatially resolved spectral analysis on a set of
homogeneous regions. We applied a recently developed diagnostic tool to compare
spectral analysis results with predictions of theoretical models, and to
estimate the efficiency of thermal conduction on the X-ray emitting shocked
plasma. We found that the inhomogeneous cavity wall contains both large clumps
(the protrusion) and small isolated clumps with different densities. A large
indentation bent over to the south is detected. The abundance of the
surrounding ISM is ~0.2 times solar value. We confirmed the important role of
thermal conduction in the evolution of X-ray emitting plasma during shock-cloud
interaction.
