Electron acceleration by young supernova remnant blast waves

Some general considerations regarding relativistic particle acceleration by young supernova remnants are reviewed. Recent ratio observations of supernova remnants apparently locate the bounding shock and exhibit large electron density gradients which verify the presence of strong particle scattering. The ratio ‘‘rim’’ in Tycho’s remnant has been found to constrain a predominantly radial magnetic field. This may be attributable to an instability of the shock surface, and a progress report on an investigation of the stability of strong shocks in partially ionized media is presented.