Concept and preliminary design of dielectric resonator for anisotropic measurement of the surface impedance

Abstract

The surface impedance of superconductors as a function of intense (∼ 10 T) static magnetic field at varying orientations with respect to the crystallographic axes is of large interest for both characterization purposes, in view of the material engineering, and from the point of view of devices to be used in fundamental physics experiments. A varying field orientation is customarily obtained with mechanically rotating magnets, whose complexity limits the attainable maximum fields to a few T. Here we propose a special proof of concept design for a measuring cell in which the magnetic field orientation is fixed, while the sample orientation can be changed through its incorporation in a rotating portion of the cell. The main design choices are thus proposed for the measuring cell: a cylindrical dielectric loaded resonator, to be used within the surface perturbation approach for the measurement of the surface impedance of flat samples with typical size 10×10mm². The main focus in this preliminary work is put on the sensitivity attainable on the surface resistance, i.e. the real part of the surface impedance.The surface impedance of superconductors in function of intense (∼ 10 T) static magnetic field at varying orientations with respect to the crystallographic axes is of large interest for both characterization purposes, in view of the material engineering, and from the point of view of devices to be used in fundamental physics experiments. A varying field orientation is customarily obtained with mechanically rotating magnets, whose complexity limits the attainable maximum fields to a few T. Here we propose a special proof of concept design for a measuring cell in which the magnetic field orientation is fixed, while the sample orientation can be changed through its incorporation in a rotating portion of the cell. The main design choices are thus proposed for the measuring cell: a cylindrical dielectric loaded resonator, to be used within the surface perturbation approach for the measurement of the surface impedance of flat samples with typical size 10 × 10 mm². The main focus in this preliminary work is put on the sensitivity attainable on the surface resistance, i.e. the real part of the surface impedance.