A cryogenic magnetic current sensor has been constructed and tested for operation and sensitivity in the ac regime. The sensor is based on a ferromagnetic-core current transformer,coupled to a superconducting-quantum-interference- device (SQUID) current detector. The SQUID electronics provides a voltage output that can be coupled to room temperature signal recovery electronics, such as a lock-in amplifier. Working in liquid helium (4.2 K) the sensor transresistance is about 1.8 Mohm in the audio frequency range; the equivalent input current noise of the sensor, at the frequency of 1 kHz, is a few pAHz−1/2 per unit primary winding turn. A major contribution to the detector noise is the thermal noise of the ferromagnetic core; however, an important excess noise contribution at low frequency is also present. The experiment is intended as a feasibility test towards the realization of high-sensitivity electromagnetic devices, such as current comparators, to be employed in primary current and impedance metrology setups working in the audio frequency range.

A magnetic current sensor with SQUID readout / Callegaro, Luca; Trinchera, BRUNO OTTAVIO; Roncaglione Tet, L.. - (2014), pp. 98-102. (Intervento presentato al convegno 20th IMEKO TC-4 International Symposium tenutosi a Benevento, Italy nel 15-17 September 2014).

A magnetic current sensor with SQUID readout

CALLEGARO, LUCA;TRINCHERA, BRUNO OTTAVIO;
2014

Abstract

A cryogenic magnetic current sensor has been constructed and tested for operation and sensitivity in the ac regime. The sensor is based on a ferromagnetic-core current transformer,coupled to a superconducting-quantum-interference- device (SQUID) current detector. The SQUID electronics provides a voltage output that can be coupled to room temperature signal recovery electronics, such as a lock-in amplifier. Working in liquid helium (4.2 K) the sensor transresistance is about 1.8 Mohm in the audio frequency range; the equivalent input current noise of the sensor, at the frequency of 1 kHz, is a few pAHz−1/2 per unit primary winding turn. A major contribution to the detector noise is the thermal noise of the ferromagnetic core; however, an important excess noise contribution at low frequency is also present. The experiment is intended as a feasibility test towards the realization of high-sensitivity electromagnetic devices, such as current comparators, to be employed in primary current and impedance metrology setups working in the audio frequency range.
2014
20th IMEKO TC-4 International Symposium
15-17 September 2014
Benevento, Italy
none
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11696/31945
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 0
  • ???jsp.display-item.citation.isi??? ND
social impact