Now that researchers have observed the condensation of a gas of helium in its metastable state, helium is the first atom to form a Bose condensate in two phases.
This article first provides guide lines for the understanding of laser cooling and Bose Einstein Condensation, with a general bibliography of the domain. Some details are given about the case of an ultracold gas of helium atoms in the 23S1 metastable state. Obtention of BEC will be recalled, with discussion of the inhibition of Penning ionization collisions. Recent studies at ENS with photoassociation methods will be summarized, including the formation of giant dimers providing another example of ionization inhibition.