Cooling by flow through narrow pores
Journal or Book Title
Low Temperature Physics, Pts A and B
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.
Book Series Title
AIP CONFERENCE PROCEEDINGS
Mullin, WJ and Kalechofsky, N, "Cooling by flow through narrow pores" (2006). Low Temperature Physics, Pts A and B. 28.
Retrieved from https://scholarworks.umass.edu/physics_faculty_pubs/28