How to reach the collisional regime on a magnetically guided atomic beam
  In this paper, we report our progress towards the realization of a continuous guided atomic beam in the degenerate regime. So far, we have coupled into a magnetic guide a flux of a few $10^{8}$ atoms/s at 60 cm/s with a propagation in the guide over more than 2 meters. At this stage, the collision rate is not high enough to start an efficient forced evaporative cooling. Here we describe a new approach to reach the collisional regime. It is based on a pulsed feeding of the magnetic guide at a high repetition rate. The overlap of the packets of atoms occurs in the guide and leads to a continuous guided beam. We discuss different ways to increase the collision rate of this beam while keeping the phase space density constant by shaping the external potential. 
J. M. Vogels, T. Lahaye, C. Roos, J. Dalibard, D. Guery-Odelin