We predict and analyze nontrivial relaxational behavior of magnetically trapped gases near the Bose-condensation temperature ${\mathit{T}}_{\mathit{c}}$. Due to strong compression of the condensate by the inhomogeneous trapping field, particularly at low densities, the relaxation rate shows a strong, almost jumplike, increase below ${\mathit{T}}_{\mathit{c}}$. As a consequence the maximum fraction of condensate particles is limited to a few percent. This phenomenon can be called a ‘‘relaxation explosion.’’ We discuss its implication for the detectability of Bose-Einstein condensation in atomic hydrogen.

• Received 30 June 1993

DOI:https://doi.org/10.1103/PhysRevB.48.12886