Cryogenic Current Comparators for Larger Beamlines

Transmission operators for the non-overlapping Schwarz method for solving Helmholtz problems in rectangular cavities

“…see the cryostat discussed in [29]). Such acoustic noise analyses can become critical, for instance, when designing a cryogenic current comparator (CCC) with a large bore [30]. A CCC is one of the most sensitive instrument for measuring very low electric currents with high accuracy and can be used e.g.…”

“…A CCC is one of the most sensitive instrument for measuring very low electric currents with high accuracy and can be used e.g. in particle accelerators for the non-destructive monitoring of slowly extracted charged particle beams (current intensities below 1µA) [30].…”

Influence of Mechanical Deformations on the Performance of a Coaxial Shield for a Cryogenic Current Comparator

“…For illustration purposes, this configuration exhibits the following resonance frequencies: f Mode I 31 Hz, f Mode II 37 Hz, f Mode III 42 Hz, f Mode VI 43 Hz and f Mode V 79 Hz. In the more realistic case of the FAIR-CCC 5 [11], the fundamental mode has been found at approximately 80 Hz, by assuming however that the CCC is clamped at its inner radius.…”

“…This perfect diamagnetism is attributed to shielding currents, which are in practice well described by the London theory [24], as CCCs are usually made of thick superconductors (e.g. 3 mm in the case of the FAIR-CCC [11] or 1 mm for the CCC discussed in [5]) held well below the critical temperature. In this theoretical framework, and by neglecting the displacement currents 8 , the London equation do not contain any dynamics.…”

“…Their impact may become non-negligible when considering devices with a large radius and weight. Moreover, when considering such devices, low-frequency mechanical vibrations are triggered by the acoustic environment, increasing thus the background noise sensed by the whole CCC [11], [12]. Therefore, in order to tackle the aforementioned problems, this paper aims at i) presenting a numerical framework for quantifying the impact of static mechanical deformations on the coaxial CCC shield performance; ii) determining whether static mechanical deformations impact significantly the coaxial CCC shield noise performance and iii) motivating a quasi-static approach for studying to the impact of mechanical vibrations.…”