  We study the acceleration and radiation of charged particles in the shock
waves of supernova remnants using a recent version of the "box model".
According to this, particles are accelerated in an energy-dependent region
around the shock by the first order Fermi mechanism and lose energy through
radiation. The particle distribution function is obtained from a spatially
averaged kinetic equation that treats the energy losses self-consistently.
There exists also a second population that consists of those particles that
escape behind the shock where they also radiate. The energy distribution of
this population is calculated in a similar manner. The application of the model
to the supernova remnant RX J1713.7-3946, which was recently confirmed as a TeV
source by H.E.S.S., shows that the X-ray emission can be attributed to electron
synchrotron radiation while in gamma-rays there are contributions from both
electrons and protons, with protons playing the dominant role. Additionally,
there are strong indications that particles diffuse in turbulence that has a
Kolmogorov spectrum.
