Anomalous cooling of the parallel velocity in seeded beams: theory and experiments

Alain Miffre (1) , Marion Jacquey (1) , Matthias Büchner (1) , Gérard Trénec (1) , Jacques Vigué (1)

1 LCAR - Laboratoire Collisions Agrégats Réactivité

We have found recently that, in a supersonic expansion of a mixture of two monoatomic gases, the parallel temperatures of the two gases can be very different. This effect is large if the seeded gas is highly diluted and if its atomic mass is considerably smaller than the one of the carrier gas. In the present paper, we present a complete derivation of our theoretical analysis of this effect. Our calculation is a natural extension of the existing theory of supersonic cooling to the case of a gas mixture, in the high dilution limit. Finally, we describe a set of temperature measurements made on a beam of lithium seeded in argon. Our experimental results are in very good agreement with the results of our calculation.

Mots clés: seeded beams; parallel velocity; supersonic expansion; parallel temperature

Domaines: Physique Atomique [physics.atom-ph]

Alain Miffre, Marion Jacquey, Matthias Büchner, Gérard Trénec, Jacques Vigué. Anomalous cooling of the parallel velocity in seeded beams: theory and experiments. 2004. ⟨hal-00002148v1⟩