Visible to the public Biblio

Filters: Keyword is Magnetic field measurement  [Clear All Filters]
2020-11-30
Beran, P., Klöhn, M., Hohe, H..  2019.  Measurement Characteristics of Different Integrated Three-Dimensional Magnetic Field Sensors. IEEE Magnetics Letters. 10:1–5.
Datasheets of different commercially available integrated sensors for vector measurements of magnetic fields provide typical specifications, such as measurement range, sampling rate, resolution, and noise. Other characteristics of interest, such as linearity, cross-sensitivity, remanent magnetization, and drifts over temperature, are mostly missing. This letter presents testing results of those characteristics of integrated three-dimensional (3-D) sensors working with different sensor principles and technologies in a reproducible measuring process. The sensors are exposed to temperatures from -20 °C to 80 °C and are cycled in hysteresis loops in fields up to 2.5 mT. For applying high-accuracy magnetic fields, a calibrated 3-D Helmholtz coil setup is used. Commercially available integrated 3-D magnetic field sensors are put in operation on a printed circuit board using nonmagnetic passive components. All sensors are configured for best measurement accuracy according to their data-sheets. The results show that sensors based on anisotropic magnetoresistance have high accuracy and low offsets yet also a high degree of nonlinearity. Hall-based sensors show good linearity but also high cross-sensitivity. A magnetic remanence appears for Hall-based sensors with integrated magnetic concentrators as well as for sensors using anisotropic magnetoresistance. Nearly all sensors show remaining drifts over temperature regarding offset and sensitivity up to several percentages.
2020-02-24
Kroon, Martin, Bongers, Ed, Bubeck, Klaus.  2019.  Magnetic tests and analysis of JUICE solar array. 2019 European Space Power Conference (ESPC). :1–5.
Very sensitive magnetic instruments on the JUICE spacecraft require an extremely low magnetic field emission of the various subsystems. The JUICE solar array includes a photovoltaic assembly and various mechanisms with a magnetic signature. The design of the photovoltaic assembly has been optimised not only with respect to magnetic moment, but also with respect to the emitted magnetic field, by applying the so-called back-wiring technique, alternating string polarity etc. The remanent magnetic field of the mechanisms (hinges, eddy-current damper, hold-down & release mechanism) was tested including a process for demagnetisation. In addition, the temperature coefficient for the magnetic moment was measured, down to the operational temperature of -130°C. The eddy-current damper was also subjected to a field-induced magnetisation test. All the contributors were included in a model to calculate the magnetic field at the instrument location.
Moritz, Pierre, Mathieu, Fabrice, Bourrier, David, Saya, Daisuke, Blon, Thomas, Hasselbach, Klaus, Kramer, Roman, Nicu, Liviu, Lacroix, Lise-Marie, Viau, Guillaume et al..  2019.  Development Of Micro-Magnets For The Electromagnetic Transduction Of MEMS. 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems Eurosensors XXXIII (TRANSDUCERS EUROSENSORS XXXIII). :1748–1751.
This paper presents a new class of high-performance permanent micro-magnets based on the controlled assembly of cobalt nanorods for the electromagnetic transduction of MEMS. Micromagnets are fabricated using a low temperature fabrication process that yields a dense material exhibiting high coercive field and remanence to saturation magnetization ratio. The cartography of the magnetic induction produced by the sub-millimeter size magnets was obtained using a scanning Hall effect micro-probe microscope. Silicon microcantilevers placed in the vicinity of these magnets were successfully actuated using the Lorentz force with low currents. The good signal to noise ratio measured at resonance demonstrates the potentiality of these nanostructured micro-magnets.
2019-03-25
Pawlenka, T., Škuta, J..  2018.  Security system based on microcontrollers. 2018 19th International Carpathian Control Conference (ICCC). :344–347.
The article describes design and realization of security system based on single-chip microcontrollers. System includes sensor modules for unauthorized entrance detection based on magnetic contact, measuring carbon monoxide level, movement detection and measuring temperature and humidity. System also includes control unit, control panel and development board Arduino with ethernet interface connected for web server implementation.
2019-01-16
Yang, H. F., Hu, X. K., Sievers, S., Bohnert, T., Costa, J. D., Tarcquzzaman, M., Ferreira, R., Bieler, M., Schumacher, H. W..  2018.  Coherent Control of Acoustic-Wave-Induced Magnetization Dynamics in Magnetic Tunnel Junctions. 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018). :1–2.
We report time-domain measurements of acoustic-wave-induced magnetization dynamics in magnetic tunnel junctions. The acoustic pulses are generated by femtosecond laser excitation and interact with the magnetization through magnetoelastic coupling. The induced magnetization precession is not only dependent on the externally applied magnetic field, but also on the laser excitation position. The presented method even allows us to coherently control the precession using two laser pulses at various magnetic fields and excitation positions.
2018-05-16
Kim, M., Park, H., Kim, C., Park, S. K., Ri, H. C..  2017.  The Relation Between Local Hysteresis Losses and Remanent Magnetic Fields in HTSC Films. IEEE Transactions on Applied Superconductivity. 27:1–4.

Various critical state models have been developed to understand the hysteresis loss mechanism of high-temperature superconducting (HTSC) films. The analytic relation between the hysteresis loss and the remanent field was obtained based on Bean's critical state model for thin films in the full-penetration case. Furthermore, numerical calculation of local hysteresis loops was carried out by Kim's critical state model. In this paper, we investigated local hysteresis losses for a GdBCO coated conductor by using low-temperature scanning Hall probe microscopy and reproduced the experimental results by applying the critical state model. Because of the demagnetizing effect in thin films, analysis of local hysteresis losses can be useful approach to understand of total hysteresis losses.

Ciovati, G., Cheng, G., Drury, M., Fischer, J., Geng, R..  2017.  Impact of Remanent Magnetic Field on the Heat Load of Original CEBAF Cryomodule. IEEE Transactions on Applied Superconductivity. 27:1–6.

The heat load of the original cryomodules for the continuous electron beam accelerator facility is 50% higher than the target value of 100 W at 2.07 K for refurbished cavities operating at an accelerating gradient of 12.5 MV/m. This issue is due to the quality factor of the cavities being 50% lower in the cryomodule than when tested in a vertical cryostat, even at low RF field. Previous studies were not conclusive about the origin of the additional losses. We present the results of a systematic study of the additional losses in a five-cell cavity from a decommissioned cryomodule after attaching components, which are part of the cryomodule, such as the cold tuner, the He tank, and the cold magnetic shield, prior to cryogenic testing in a vertical cryostat. Flux-gate magnetometers and temperature sensors are used as diagnostic elements. Different cool-down procedures and tests in different residual magnetic fields were investigated during the study. Three flux-gate magnetometers attached to one of the cavities installed in the refurbished cryomodule C50-12 confirmed the hypothesis of high residual magnetic field as a major cause for the increased RF losses.

Liren, Z., Xin, Y., Yang, P., Li, Z..  2017.  Magnetic performance measurement and mathematical model establishment of main core of magnetic modulator. 2017 13th IEEE International Conference on Electronic Measurement Instruments (ICEMI). :12–16.

In order to investigate the relationship and effect on the performance of magnetic modulator among applied DC current, excitation source, excitation loop current, sensitivity and induced voltage of detecting winding, this paper measured initial permeability, maximum permeability, saturation magnetic induction intensity, remanent magnetic induction intensity, coercivity, saturated magnetic field intensity, magnetization curve, permeability curve and hysteresis loop of main core 1J85 permalloy of magnetic modulator based on ballistic method. On this foundation, employ curve fitting tool of MATLAB; adopt multiple regression method to comprehensively compare and analyze the sum of squares due to error (SSE), coefficient of determination (R-square), degree-of-freedom adjusted coefficient of determination (Adjusted R-square), and root mean squared error (RMSE) of fitting results. Finally, establish B-H curve mathematical model based on the sum of arc-hyperbolic sine function and polynomial.