Cooling by flow through narrow pores

Publication Date

2006

Journal or Book Title

Low Temperature Physics, Pts A and B

Abstract

We consider the possibility of cooling 3He atoms in dilute solutions with liquid 4He by “filtering out” the hot atoms through a screen of small holes or channels. The proposed method is somewhat analogous to that employed to evaporatively cool trapped gases, and the specific heat of the 3He-4He mixture makes it feasible to use in a device to refrigerate other samples. Three methods are considered: 1) Effusion through holes having diameters larger than a mean free path allowing atoms to pass through easily; 2) Particle waveguide-like motion (also effusive) using very narrow channels that greatly restrict the quantum states of the atoms in them; and 3) Wall-limited diffusion through channels of various widths, in which the wall scattering is disordered so that local density equilibrium is established within a channel. The methods studied all require sufficiently low temperatures and holes or channels with sufficiently small dimensions that temperature equilibrium between the escaping gas and the original gas is avoided; that is, we assume that channel dimensions are smaller than the mean free path for atom-atom interactions. We find that the particle waveguide and the wall-limited diffusion methods using channels on the order of the de Broglie wavelength give cooling. Recent advances in nano-filters give these methods some hope of being practical.

Comments

Published version located at http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=APCPCS000850000001001563000001&idtype=cvips&gifs=yes&ref=no

Pages

1563-1564

Volume

850

Book Series Title

AIP CONFERENCE PROCEEDINGS

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