Cryogenic Current Comparator Metrology

Gutmann, P.; Bachmair, Hans

doi:10.1007/978-3-642-95592-1_10

Cited by 9 publications

(4 citation statements)

References 17 publications

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“…The QHE device is held in a low temperature probe in the 5 T to 14 T field of the superconducting magnet. The Hall resistance of the quantised Hall sample is compared to that of the Kibble balance resistor using a cryogenic current comparator [ 68 , 69 ]. The voltages at the potential terminals of the two resistors are adjusted to be equal by passing different currents through them and the ratio of the resulting currents is measured using a technique which makes use of the Meissner effect.…”

Section: Design and Operation Of Kibble Balancesmentioning

confidence: 99%

The watt or Kibble balance: a technique for implementing the new SI definition of the unit of mass

2016

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The redefinition of the SI unit of mass in terms of a fixed value of the Planck constant has been made possible by the Kibble balance, previously known as the watt balance. Once the new definition has been adopted, the Kibble balance technique will permit the realisation of the mass unit over a range from milligrams to kilograms. We describe the theory underlying the Kibble balance and practical techniques required to construct such an instrument to relate a macroscopic physical mass to the Planck constant with an uncertainty, which is achievable at present, in the region of 2 parts in 10 8 . A number of Kibble balances have either been built or are under construction and we compare the principal features of these balances.

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Section: Design and Operation Of Kibble Balancesmentioning

confidence: 99%

The watt or Kibble balance: a technique for implementing the new SI definition of the unit of mass

2016

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“…When applied to the shielding of the TESLA CCC, an attenuation factor of approximately 120 dB for transverse, non-azimuthal magnetic field components is estimated. This result is based on the superposition of the analytic results for the different shielding substructures, in this case coaxial cylinders and 'ring cavities' (as described in detail in [9]). …”

Section: Superconductive Shieldsmentioning

confidence: 99%

A new measurement tool for characterization of superconducting rf accelerator cavities using high-performance LTS SQUIDs

Vodel

Neubert

Nietzsche

et al. 2007

Supercond. Sci. Technol.

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This paper presents a new system to measure very low currents in an accelerator environment, using a cryogenic current comparator (CCC). In principle a CCC is a conventional current transformer using the high-performance SQUID technology to sense the magnetic fields caused by the beam current. Since the system is sensitive on a pA level, it is an optimum device to detect dark currents of superconducting cavities. The system presented here is designed for the test facilities of the superconducting accelerator modules for the European XFEL at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Measurements in a quiet environment showed that an intrinsic noise level of the CCC of 40 pA Hz −1/2 could be achieved.

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“…Applied to the shielding of the TESLA CCC an attenuation factor of approximately 120 dB for transverse, non-azimuthal magnetic field components is estimated. This result is based on the superposition of the analytic results for the different shielding substructures, in this case coaxial cylinders and "ring cavities" (as described in detail in [9]). …”

Section: B Superconductive Shieldsmentioning

confidence: 99%

An LTS-SQUID Based Measurement Tool for Characterization of Superconductive RF Cavities

Vodel¹,

Neubert²,

Nietzsche³

et al. 2007

IEEE Trans. Appl. Supercond.

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The linear accelerator technology, based on superconducting L-band (1.3 GHz) cavities, is currently under study at DESY [1]. The XFEL will be equipped with a total of 116 superconducting acceleration modules each containing 8 "nine cell cavities". A gradient of 23.4 MV/m is required for a socalled superstructure arrangement of couples of 9-cell cavities. Higher gradients up to the physical limit at 50 MV/m are desired. The dark current, due to emission of electrons in these high gradient fields, is an unwanted particle source. Two issues are of main concern:Abstract-This paper presents a new system to measure very low currents in an accelerator environment, using a Cryogenic Current Comparator (CCC). In principle a CCC is a conventional current transformer using the high performance SQUID technology to sense the magnetic fields caused by the beam current. Since the system is sensitive on a pA level, it is an optimum device to detect dark currents of superconducting cavities. The system presented here is designed for the test facilities of the superconducting accelerator modules for the European XFEL at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Measurements in a quiet environment showed that an intrinsic noise level of the CCC of 40 pA/√Hz could be achieved.

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Cryogenic Current Comparator Metrology

Cited by 9 publications

References 17 publications

The watt or Kibble balance: a technique for implementing the new SI definition of the unit of mass

The watt or Kibble balance: a technique for implementing the new SI definition of the unit of mass

A new measurement tool for characterization of superconducting rf accelerator cavities using high-performance LTS SQUIDs

An LTS-SQUID Based Measurement Tool for Characterization of Superconductive RF Cavities

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