The maximum energy of cosmic rays accelerated by supernova shocks.

An attempt is made to evaluate the maximum energy, E(max), that particles subjected to the diffusive shock acceleration process can acquire during an SNR's lifetime. The rate of acceleration depends on the particle diffusion coefficient, which is determined by the level of hydromagnetic wave energy present at a scale that is comparable to the particle Larmor radius. Attention is given to diffusion coefficient variations as a function of momentum, space, and time. Given a realistic diffusion coefficient behavior value, an E(max) of less than about 10,000 GeV/n is obtained, signifying that supernova shock acceleration cannot account for the observed spectrum of galactic cosmic rays in the 1-1,000,000 GeV/n energy range.