  Supernova remnants are among the most spectacular examples of astrophysical
pistons in our cosmic neighborhood. The gas expelled by the supernova explosion
is launched with velocities ~ 1000 km/s into the ambient, tenuous interstellar
medium, producing shocks that excite hydrogen lines. We have used an optical
integral-field spectrograph to obtain high-resolution spatial-spectral maps
that allow us to study in detail the shocks in the northwestern rim of
supernova 1006. The two-component H\alpha\ line is detected at 133 sky
locations. Variations in the broad line widths and the broad-to-narrow line
intensity ratios across tens of atomic mean free paths suggest the presence of
suprathermal protons, the potential seed particles for generating high-energy
cosmic-rays.
