  We present experimental results demonstrating that the flux of a continuous
atom laser beam cannot be arbitrarily increased by increasing the strength of
output-coupling. We find that a state changing output-coupler for a continuous
atom laser switches off as the output-coupling strength, parameterized by the
Rabi frequency, is increased above a critical value of four times the radial
trapping frequency. In addition, we find that the continuous atom laser has
large classical fluctuations when the Rabi frequency is greater than the radial
trapping frequency, due to the output-coupling populating all accessible Zeeman
states. The numerical solution of a one-dimensional 5-state Gross-Pitaevskii
model for the atom laser is in good qualitative agreement with the experiment.
