  The observed properties of the close binary AE Aqr indicate that the mass
transfer in this system operates via the Roche lobe overflow mechanism, but the
material transferred from the normal companion is neither accreted onto the
surface of the white dwarf nor stored in a disk around its magnetosphere. As
previously shown, such a situation can be realized if the white dwarf operates
as a propeller. At the same time, the efficiency of the propeller action by the
white dwarf is insufficient to explain the rapid braking of the white dwarf,
which implies that the spin-down power is in excess of the bolometric
luminosity of the system. To avoid this problem we have simulated the
mass-transfer process in AE Aqr assuming that the observed braking of the white
dwarf is governed by a pulsar-like spin-down mechanism. We show that the
expected H_alpha Doppler tomogram in this case resembles the tomogram observed
from the system. We find that the agreement between the simulated and the
observed tomograms is rather good provided the mean value of the mass-transfer
rate <\dot{M}> ~5x10^16 g/s. Three spatially separated sources of H_alpha
emission can be distinguished within this approach. The structure of the
tomogram depends on the relative contributions of these sources to the H_alpha
emission and is expected to vary from night to night.
