Self-Consistent Effects of Continuous Wave Output Coupling of Atoms from a Bose-Einstein Condensate

We present a self-consistent mean field model of the extraction of atoms from a Bose-Einstein condensate to form a CW atom laser. The model is based upon the Hartree-Fock Bogoliubov equations within the Popov approximation, modified by the inclusion of spatially dependent source and sink terms, which lead to current flow within the condensate. The effects of this current flow are investigated for traps containing Rubidium (repulsive effective interaction) and Lithium (attractive interaction) atoms. The extra kinetic energy associated with this flow is shown to be able to stabilise the condensate in the attractive case against mechanical instability.