7–11 Jul 2014
Europe/Amsterdam timezone

Building a thinner gap in a Gas Gap Heat Switch

8 Jul 2014, 14:15
1h 45m
Poster presentation (105min) C-16: Instrumentation and process control Tue-Af-Posters Session 1.4

Speaker

Prof. Isabel Catarino (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal)

Description

A gas gap heat switch (GGHS) reaches its highest conductance state when the gap between two exchange surfaces is filled with a conducting gas in a viscous regime. The broader the surface and the thinner the gap, the higher the ON conductance achieved. In this presentation we describe a very thin cold gas gap heat switch based upon the use of the differential thermal expansion of the construction materials. Such a technique overcomes the intricacies of the manufacturing process of the switch. We designed, built and tested a prototype of a very thin gap heat switch using our new methodology. The high conductance was measured with both helium and nitrogen, at temperatures ranging from 20 K (He) or 75 K (N2) up to room temperature. The inferred gap opening at low temperature (≈ 17 μm) showed up to be slightly above the expected, which allowed us to reinterpret the design calculations performed. The switch was also characterized along its extreme conductance states while using a sorption pump, and its performance was compared with a previously developed model. Lessons learned from first prototype led us to build up a second one with better performances. Our experiments suggest that the proposed design allows the development of a customized cryogenic switch with improved ON conductance while keeping the assembly very simple and sturdy, hence widening the scope of the applicability of these devices.

Primary authors

Mr Bruno Galinhas (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal) Mr João Franco (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal)

Co-authors

Ms Daniel Martins (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal) Prof. Grégoire Bonfait (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal) Prof. Isabel Catarino (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal) Ms Patricia Borges de Sousa (CEFITEC, Departamento de Física, FCT - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal)

Presentation materials