  We observe the spontaneous evaporation of atoms confined in a bubble-like
rf-dressed trap (Zobay and Garraway, 2001). The atoms are confined in a
quadrupole magnetic trap and are dressed by a linearly polarized rf field. The
evaporation is related to the presence of holes in the trap, at the positions
where the rf coupling vanishes, due to its vectorial character. The final
temperature results from a competition between residual heating and evaporation
efficiency, which is controlled via the height of the holes with respect to the
bottom of the trap. The experimental data are modeled by a Monte-Carlo
simulation predicting a small increase in phase space density limited by the
heating rate. This increase was within the phase space density determination
uncertainty of the experiment.
