Parametrization of the niobium thermal conductivity in the superconducting state

Abstract

Thermal conductivity measurements of niobium sheets manufactured for deep-drawing of superconducting cavities have been gathered. Due to the differing histories of the niobium samples and a wide range of metal purities (35 < RRR < 1750), the data demonstrate a large scatter of thermal conductivities. An attempt was made to obtain an analytical expression with realistic parameters for the thermal conductivity between 1.8 K and 9.25 K. The set of parameters deduced from a least square fit of experimental data is not very different from those yielded by the theory of superconducting metals, taken as a starting point. This should make it possible to obtain a reasonable estimate of the thermal conductivity of niobium in this temperature range, once the RRR and the past history of the metal samples had been determined.

Development of large grain cavities

“…Finally, after additional six HPR, a rotating T mapping was done on the cavity AC158. The break down position was found in mode in cell 8 near the equator at 170 at 44 MV=m with Q 0 ¼ 1:4 Â 10 10 .…”

“…An empirical expression for quantitative estimation of the thermal conductivity of niobium at low temperatures was proposed in the work [10], Eq. (1):…”

Physical Properties of Niobium and Specifications for Fabrication of Superconducting Cavities

“…In the 3K-15K range there is a direct relationship between RRR and thermal conductivity [4]. At 4.2 K the thermal conductivity is roughly equal to RRR/4 [5].…”

Constitutive equations for heat conduction in nanosystems and nonequilibrium processes: an overview

“…Although the thermal conductivity λ of thermoelectric materials is usually dominated by that of the electrons, in several cases the lattice heat conductivity, due to the phonons, has to be added [62]. Therefore, in the denominator of Eq.…”