Kinetics of the evaporative cooling of an atomic beam

TL;DR

This paper compares two models of evaporative cooling in atomic beams, demonstrating their equivalence and analyzing how potential shape influences rethermalization kinetics.

Contribution

It introduces a mapping between continuous and discrete-step models of evaporative cooling, highlighting the impact of potential shape on rethermalization.

Findings

Models can be mapped onto each other

Rethermalization kinetics depend on potential shape

Semi-linear potential used for calculations

Abstract

We compare two distincts models of evaporative cooling of a magnetically guided atomic beam: a continuous one, consisting in approximating the atomic distribution function by a truncated equilibrium distribution, and a discrete-step one, in which the evaporation process is described in terms of successive steps consisting in a truncation of the distribution followed by rethermalization. Calculations are performed for the semi-linear potential relevant for experiments. We show that it is possible to map one model onto the other, allowing us to infer, for the discrete-step model, the rethermalization kinetics, which turns out to be strongly dependent upon the shape of the confining potential.