Abstract
In this paper we report on measurements and simulations of superconducting tubes in the presence of inhomogeneous externally applied magnetic fields in a cryogenic environment. The shielding effect is studied for two different tube materials, Pb and Nb, employing Hall sensors in a tabletop experiment. The measured internal and external fields of the tubes agree with the theory of the Meissner-Ochsenfeld effect [1], field trapping of type 2 superconductors, phase transitions and tube geometries. The obtained measurements are compared to a finite element simulation. Next, the simulation model is applied to estimate the shielding effect in the vicinity of a cryogenic Penning trap experiment. The controlled suppression of external magnetic fields is important for future precision experiments in atomic and antimatter physics in cryogenic environments.
Highlights
- Any light particle search II — Technical Design Report R Bähre, B Döbrich, J Dreyling-Eschweiler et al
: In this paper we report on measurements and simulations of superconducting tubes in the presence of inhomogeneous externally applied magnetic fields in a cryogenic environment
The controlled suppression of external magnetic fields is important for future precision experiments in atomic and antimatter physics in cryogenic environments
Summary
The process of field trapping is studied in more detail. During cooldown the magnet was initially positioned at the side of the tube at h2 = 0 and at the radial distance r = 32 mm. In the long Pb tube, figure 4a, the inner Hall sensor recorded a change of the magnetic field despite being in the SC-phase. This is explained as the flux lines in the Shubnikov phase [16] leaked into the tube. For the long Nb tube, figure 4b, the plot on the left side of the blue line indicates the trapped field when the magnet was at the close-by position h2 = 0 mm and r = 27 mm at the time when the tube became a SC. At a temperature of 11.5 K, the red line indicates when the magnet was brought back to the close-by position of h2 = 0 mm and r = 27 mm.
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