Transformer-based measurement of critical currents in superconducting cables: tutorial 51
TL;DR: The promises arising from High Temperature Superconductors (Tc>77 K) would extend the range of application, for instance, to power distribution and the generation of electrical energy with tokamaks.
Abstract: Superconductivity is a technology with a declared interest in several fields of physics and engineering. Nowadays, superconducting cables [1] are largely exploited in fields such as particle colliders [2] and medical machines [3]. The generation of electrical energy with tokamaks [4] is a further application of low-temperature superconductivity as well. Moreover, the promises arising from High Temperature Superconductors (Tc>77 K) would extend the range of application, for instance, to power distribution [5]-[6].
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TL;DR: An improved force measurement system was developed for investigating high-temperature superconducting (HTS) maglev properties and features high precision, instant measurement at the movement of the targeted HTS bulk, synchronous measurement of levitation force and guidance force, and the magnetic field.
Abstract: An improved force measurement system was developed for investigating high-temperature superconducting (HTS) maglev properties. The measurement system consists of assorted sensors, a 3-D sliding platform, a mechanical drive with automatic control software, and a data collecting and processing software. This system features high precision, instant measurement at the movement of the targeted HTS bulk, synchronous measurement of levitation force and guidance force, and the magnetic field. This system can be used for studying the interaction behavior between an HTS bulk and a permanent magnet guideway (PMG) or an electromagnetic guideway (EMG) of different shapes and sizes. It can realize arbitrary 3-D complex curvilinear motions. This system was built with a flexible platform and high precision force and distance sensors. As a result, the magnetic levitation characteristics of an HTS bulk above a magnet guideway can be precisely investigated with this system. In general, the aforementioned functions all have been verified by experiments.
19 citations
Cites background from "Transformer-based measurement of cr..."
...S INCE the discovery of the high-temperature superconducting (HTS) phenomenon, HTS materials have attracted extensive attention in many fields such as power industry [1]–[4], rail transit [5], [6], flywheel energy storage [7], [8], and measurement calibration [9], [10] due to their unique characteristics....
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CERN1
TL;DR: In this paper, the CryoDCCT has been used for measuring the secondary current of a 80 kA superconducting transformer feeding a sample of NbSn 3 cable at the Facility for Research on Superconducting Cables (FRESCA) at CERN.
Abstract: A new cryogenic dc current transformer (Cryo-DCCT) has recently been designed and assembled at CERN. The device, whose design is based on that of a high-accuracy 600 A market solution suitable for room temperature applications, is optimized for measuring currents of up to 80 kA and for operation at 4.2 K. The CryoDCCT has been conceived with the objective of preserving the metrological performance of the original commercial device in the new extended range of operation. For reducing the effect of interfering magnetic fields arising from test conditions, it incorporates ferromagnetic and MgB 2 superconducting shields. In this paper, the design of the CryoDCCT and the results of the commissioning of the device at CERN are reported. The effectiveness of the current transducer is analysed and discussed. This new device will be used for measuring the secondary current of a 80 kA superconducting transformer feeding a sample of NbSn 3 cable at the Facility for Research on Superconducting Cables (FRESCA) at CERN.
4 citations
Cites background from "Transformer-based measurement of cr..."
...The current must be measured via contactless sensors capable of working at cryogenic temperatures [12] (interruptions of the superconducting circuit have to be avoided)....
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TL;DR: An uncertainty model of the transducer, mainly based on a valve model, exploiting finite-element approach, and a virtual flowmeter model, based on the Sereg-Schlumberger method are presented, which are validated experimentally and turn out to be important for CERN cryogenics operation.
Abstract: The metrological performance of a virtual flowmeter-based transducer for monitoring helium under cryogenic conditions is assessed. At this aim, an uncertainty model of the transducer, mainly based on a valve model, exploiting finite-element approach, and a virtual flowmeter model, based on the Sereg-Schlumberger method, are presented. The models are validated experimentally on a case study for helium monitoring in cryogenic systems at the European Organization for Nuclear Research (CERN). The impact of uncertainty sources on the transducer metrological performance is assessed by a sensitivity analysis, based on statistical experiment design and analysis of variance. In this way, the uncertainty sources most influencing metrological performance of the transducer are singled out over the input range as a whole, at varying operating and setting conditions. This analysis turns out to be important for CERN cryogenics operation because the metrological design of the transducer is validated, and its components and working conditions with critical specifications for future improvements are identified.
1 citations
References
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CERN1
TL;DR: In this article, the beam loss monitoring (BLM) system for CERN's Large Hadron Collider (LHC) is described, including the monitor types (ionization chambers and secondary emission monitors), the design of the analogue and digital readout electronics as well as the data links and the trigger decision logic.
Abstract: One of the most critical elements for the protection of CERN's Large Hadron Collider (LHC) is its beam loss monitoring (BLM) system. It must prevent the superconducting magnets from quenching and protect the machine components from damages, as a result of critical beam losses. By measuring the loss pattern, the BLM system helps to identify the loss mechanism. Special monitors will be used for the setup and control of the collimators. The specification for the BLM system includes a very high reliability (tolerable failure rate of 10/sup -7/ per hour) and a high dynamic range of 10/sup 8/ (10/sup 13/ at certain locations) of the particle fluencies to be measured. In addition, a wide range of integration times (40 /spl mu/s to 84 s) and a fast (one turn) trigger generation for the dump signal are required. This paper describes the complete design of the BLM system, including the monitor types (ionization chambers and secondary emission monitors), the design of the analogue and digital readout electronics as well as the data links and the trigger decision logic.
70 citations
"Transformer-based measurement of cr..." refers background in this paper
...…Cables: Tutorial 51 Part 51 in a series of tutorials on instrumentation and measurement Amalia Ballarino, Giuseppe Montenero, and Pasquale Arpaia 20 9 24 47 81 56 3 1Fiftyone in aSeries Superconductivity is a technology with a de-clared interest in several fields of physics and engineering....
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CERN1
TL;DR: In this article, a new test facility for measuring the electrical properties of the LHC superconducting cables was constructed at CERN, with the main features being: independently cooled background magnet, test currents up to 32 kA, temperature between 1.8 and 4.5 K, long measurement length of 60 cm, field perpendicular or parallel to the cable face, measurement of the current distribution between the strands.
Abstract: A new test facility (FRESCA-Facility, reception of superconducting cables) is under construction at CERN to measure the electrical properties of the LHC superconducting cables. Its main features are: independently cooled background magnet, test currents up to 32 kA, temperature between 1.8 and 4.5 K, long measurement length of 60 cm, field perpendicular or parallel to the cable face, measurement of the current distribution between the strands. The facility consists of an outer cryostat containing a superconducting NbTi dipole magnet with a bore of 56 mm and a maximum operating field of 9.5 T. The magnet current is supplied by an external 16 kA power supply and fed into the cryostat using self-cooled leads. The lower bath of the cryostat, separated by means of a so called lambda-plate from the upper bath, can be cooled down to 1.9 K using a subcooled superfluid refrigeration system. Within the outer cryostat, an inner cryostat is installed containing the sample insert. This approach makes it possible to change samples while keeping the background magnet cold, and thus decreasing the helium consumption and cool-down time of the samples. The lower bath of the inner cryostat, containing the sample holder with two superconducting cable samples, can as well be cooled down to 1.9 K. The samples can be rotated while remaining at liquid helium temperature, enabling measurements with the background field perpendicular or parallel to the broad face of the cable. Several arrays of Hall probes are installed next to the samples in order to estimate possible current imbalances between the strands of the cables.
61 citations
TL;DR: A quarter of a century after the discovery of high-temperature superconductivity, there is still heated debate about how it works.
Abstract: A quarter of a century after the discovery of high-temperature superconductivity, there is still heated debate about how it works.
40 citations
CERN1
TL;DR: In this paper, a pair of ring cores are used to provide flux rate feedback to a power amplifier which drives the ampere-turn compensating current through a common compensating winding, and a specially developed burden resistor converts the compensating currents into a voltage signal, which is amplified to give a 10 V output signal at the nominal value of the current to be measured.
Abstract: A current-carrying conductor is surrounded by a pair of ring cores. A sense winding on one core provides flux rate feedback to a power amplifier which drives the ampere-turn compensating current through a common compensating winding. The other core serves as a second-harmonic modulator to establish zero-flux operation and thus to ensure a perfect, temperature-independent current balance. A specially-developed burden resistor converts the compensating current into a voltage signal, which is amplified to give a 10 V output signal at the nominal value of the current to be measured. A substantial number of devices, ranging from 50 to 25000 Amperes is now operational in the beam transfer and extraction power supplies for the CERN SPS.
35 citations
DOI•
01 Dec 1992
TL;DR: This introductory course aims at a reasonably complete coverage of beam diagnostic devices used in linear and circular accelerators and in primary beam lines.
Abstract: This introductory course aims at a reasonably complete coverage of beam diagnostic devices used in linear and circular accelerators and in primary beam lines. The weight is on the concepts and the indication of variants, while for technical details the reader is referred to the literature. The present updated version replaces those from previous General Accelerator Physics Courses.
29 citations
"Transformer-based measurement of cr..." refers methods in this paper
...Transformer-based Measurement of Critical Currents in Superconducting Cables: Tutorial 51 Part 51 in a series of tutorials on instrumentation and measurement Amalia Ballarino, Giuseppe Montenero, and Pasquale Arpaia 20 9 24 47 81 56 3 1Fiftyone in aSeries Superconductivity is a technology with a…...
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