  A small magnetic field is found to enhance relaxation processes in a
superconductor thus stabilizing superconductivity in non-equilibrium
conditions. In a normal-metal (N) - insulator - superconductor (S) tunnel
junction, applying a field of the order of 100 \mu T leads to significantly
improved cooling of the N island by quasiparticle (QP) tunneling. These
findings are attributed to faster QP relaxation within the S electrodes as a
result of enhanced QP drain through regions with locally suppressed energy gap
due to magnetic vortices in the S leads at some distance from the junction.
