Dynamics of evaporative cooling in magnetically trapped atomic hydrogen - art. no. 033602

We study the evaporative cooling of magnetically trapped atomic hydrogen on the basis of the kinetic theory of a Bose gas. The dynamics of trapped ato ms is described by the coupled differential equations, considering both the evaporation and dipolar spin relaxation processes. The numerical time-evol ution calculations quantitatively agree with the recent experiment of Bose- Einstein condensation with atomic hydrogen. It is demonstrated that the bal ance between evaporative cooling and heating due to dipolar relaxation limi ts the number of condensates to 9X10(8) and the corresponding condensate fr action to a small value of 4% as observed experimentally.