Thermal conductance characterization of a pressed copper rope strap between 0.13 K and 10 K. (September 2017)

• Record Type: Journal Article
• Authors: Dhuley, R.C.; Ruschman, M.; Link, J.T.; Eyre, J.
• Is Part Of: Cryogenics. Volume 86(2017)
• Page Start: 17
• Page End: 21
• Publication Date: 2017-09
• Subjects: Low temperature engineering -- Periodicals; Low temperature research -- Periodicals; 536.56
• DOI: 10.1016/j.cryogenics.2017.07.001
• Languages: English
• ISSNs: 0011-2275

Abstract

Highlights: Thermal conductance of a solderless copper strap is measured between 0.13 K and 10 K. Conductance near liquid helium temperatures and above varies near-linearly with temperature. Sub-Kelvin conductance follows a near-quadratic power law with temperature. Sub-Kelvin conductance is enhanced by electron-beam welding. Abstract: Mechanically pressing the ends of a copper braid in solid copper is an effective way of constructing solderless conductive straps for cryogenic applications. In this paper we present thermal conductance data of such a copper strap measured using the two-heater one-thermometer method. The measurements span a wide temperature range of 0.13–10 K applicable to a variety of cryogenic systems employing liquid helium, pulse tube coolers, adiabatic demagnetization refrigerators, and others. Above ≈1.5 K, the braid thermal conductivity dominates the strap conductance resulting in a near-linear dependence with temperature. The variation with temperature below ≈1.5 K is near-quadratic indicating dominance of the pressed contact conductance at the strap ends. Electron-beam welding the braid to the strap ends is shown to be a promising solution for improving sub-Kelvin thermal conductance of the strap.