Cold atomic beam from a two-dimensional magneto-optical trap with two-color pushing laser beams

We present an intense source of cold rubidium atoms from a two-dimensional magneto-optical trap (2D MOT) with a two-color pushing laser that generates an adjustable mean velocity ranging from 20 to 45 m/s. The dependence of the flux and velocity distribution on the pushing beam parameters such as laser detuning and laser power was investigated in detail. We obtained a flux Φ=4.5×1010atoms/s with the total laser power of 60 mW at a vapor pressure of 1.2×10−7 torr. By adding a red-detuned pushing beam (Δ−=−4.5ΓΔ−=−4.5Γ) into a blue-detuned one (Δ+=+4.5ΓΔ+=+4.5Γ) the flux was increased by more than a factor of 2. Furthermore this modified 2D MOT system improved 3D MOT loading rate to greater than 3×1010 atoms/s keeping the background pressure below 10−11 torr in the ultra-high-vacuum chamber.