| 1. |
- Branny, Artur, et al.
(författare)
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X-Ray Induced Secondary Particle Counting With Thin NbTiN Nanowire Superconducting Detector
- 2021
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Ingår i: IEEE transactions on applied superconductivity (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1051-8223 .- 1558-2515. ; 31:4
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Tidskriftsartikel (refereegranskat)abstract
- We characterized the performance of abiased superconducting nanowire to detect X-ray photons. The device, made of a 10 nm thin NbTiN film and fabricated on a dielectric substrate (SiO2, Nb3O5) detected 1000 times larger signal than anticipated from direct X-ray absorption. We attributed this effect to X-ray induced generation of secondary particles in the substrate. The enhancement corresponds to an increase in the flux by the factor of 3.6, relative to a state-of-the-art commercial X-ray silicon drift detector. The detector exhibited 8.25 ns temporal recovery time and 82 ps timing resolution, measured using optical photons. Our results emphasize the importance of the substrate in superconducting X-ray single photon detectors.
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| 2. |
- Schönborg, Niclas, et al.
(författare)
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Impact of DC components in transport current and external magnetic field on hysteresis losses in an HTS tape
- 2004
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Ingår i: IEEE transactions on applied superconductivity (Print). - 1051-8223 .- 1558-2515. ; 14:3, s. 1955-1958
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Tidskriftsartikel (refereegranskat)abstract
- The high-temperature superconductor (HTS) development is presently intensive, and one can expect that HTSs will be used in different electric devices in the future. In some of these devices, e.g., a magnetostrictive actuator, the conductor will be exposed to both ac and dc transport currents and external magnetic fields. One of the most important parameters in the design of electric devices is the power loss. It is, therefore, of importance to develop models that are able to predict the power loss in devices based on HTSs. In this paper, we present an experimental characterization of the hysteresis losses in an HTS tape exposed to ac or dc transport currents in combination with external magnetic fields. The experimental results are compared to some existing models based on the critical state model. The power loss was measured on a multifilamentary Bi-2223 tape at constant temperature (70 K) and frequency (50 Hz).
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| 3. |
- Wass, Torbjörn, et al.
(författare)
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AC losses in applied longitudinal magnetic fields at variable temperatures
- 2004
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Ingår i: IEEE transactions on applied superconductivity (Print). - 1051-8223 .- 1558-2515. ; 14:1, s. 22-27
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Tidskriftsartikel (refereegranskat)abstract
- In most power devices, the conductor is carrying anac transport current while it is exposed to an ac magnetic fieldtransverse to the current path. In certain applications, such aspower cables or a control winding in a controllable reactor, theconductors are exposed to a magnetic field component longitudinalto the tape axis that is parallel to the current path. To createan improved base for the design of such power devices it is ofinterest to study the losses in high-temperature superconductortapes due to longitudinal field in detail. We have investigated thelosses at several temperatures of a nontwisted multifilamentaryBi-2223 tape when it was exposed to a longitudinal magnetic field.The losses were measured with a calorimetric method and theresults were compared with the critical state hysteresis loss model.The hysteresis losses are dominating at power frequencies (50,60 Hz) in the investigated field range 2–200 mT and are accuratelydescribed by the critical state hysteresis model.
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| 4. |
- Wildner, Elena, et al.
(författare)
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Control of the Dipole Cold Mass Geometry at CERN to Optimize LHC Performance
- 2006
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Ingår i: IEEE transactions on applied superconductivity (Print). - 1051-8223 .- 1558-2515. ; 16:2, s. 212-215
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Tidskriftsartikel (refereegranskat)abstract
- The detailed shape of the 15 m long superconducting LHC dipole cold mass is of high importance as it determines three key parameters: the beam aperture, nominally of the order of 10 beam standard deviations; the connectivity of the beam- and technical lines between magnets; the transverse position of nonlinear correctors mounted on the dipole ends. An offset of the latter produces unwanted beam dynamics perturbations. The tolerances are in the order of mm over the length of the magnet. The natural flexibility of the dipole and its mechanical structure allow deformations during handling and transportation which exceed the tolerances. This paper presents the observed deformations of the geometry during handling and various operations at CERN, deformations which are interpreted thanks to a simple mechanical model. These observations have led to a strategy of dipole geometry control at CERN, based on adjustment of the position of its central support (the dipole is supported at three positions, horizontally and vertically) to recover individually or statistically their original shape as manufactured. The implementation of this strategy is discussed, with the goal of finding a compromise between conflicting requirements: quality of the dipole geometry, available resources for corrective actions and magnet installation strategy whereby the geometry tolerances depend on the final magnet position in the machine.
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| 5. |
- Wildner, Elena, et al.
(författare)
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Production follow-up of the LHC main dipoles through magnetic measurements at room temperature
- 2004
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Ingår i: IEEE transactions on applied superconductivity (Print). - 1051-8223 .- 1558-2515. ; 14:2, s. 173-176
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we review the tools used for controlling the production of the LHC main dipoles through warm magnetic measurements. For the collared coil measurements, control limits are based on the statistics relative to the pre-series production. For the cold mass, the difference between collared coil and cold mass is considered, allowing a very stringent test. In both cases, measurements are split in straight part average, variations and coil ends contributions. Two different alarm levels exist in case the measured field is out of limits. The analysis can be carried out at the manufacturer and allows detection of anomalies in the measured magnetic field. These can be either due to wrong measurements or caused by assembly defects. Techniques used to work out information on the magnet assembly from the field harmonics are outlined. We summarize the experience gathered on about 180 collared coils and 120 cold masses, pointing out the bad cases and investigating the reliability of the measurements.
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| 6. |
- Wolfbrandt, Anna, et al.
(författare)
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AC losses in a BSCCO/Ag tape carrying AC transport currents in AC magnetic fields applied in different orientations
- 2001
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Ingår i: IEEE transactions on applied superconductivity (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1051-8223 .- 1558-2515. ; 11:4, s. 4123-4127
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Tidskriftsartikel (refereegranskat)abstract
- In most prospective electric power applications of high-temperature superconductors (HTSs), the conductor is wound in a coil configuration. For a coil of finite length, the magnetic field orientation is axial in the middle of the coil, while the field contains a substantial radial component at the coil ends. In a superconducting BSCCO/Ag tape, the ac losses depend strongly on the orientation of the magnetic field. In this study, we present experimental results of the ac losses in a multifilamentary silver-sheathed Bi-2223 HTSs tape, carrying alternating transport currents in externally applied alternating magnetic fields at different orientations, with respect to the face of the tape and perpendicular to the transport current. The ac losses were measured calorimetrically, at fixed temperature and frequency. The results are compared to semi-empirical models of the ac losses in HTSs tape. We present a more general model of the angular dependence of the ac losses.
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