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Your search keyword '"Braginski, Alex. I."' showing total 104 results
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104 results on '"Braginski, Alex. I."'

7. HTS SQUID gradiometer using substrate resonators operating in an unshielded environment -- a portable MCG system

Author

Zhang, Yi, Wolters, Norbert, Schubert, Jurgen, Lomparski, Dieter, Banzet, Marko, Panaitov, Grigory, Krause, Hans-Joachim, Muck, Michael, and Braginski, Alex I.

Subjects
Diagnostic equipment (Medical) -- Research, Superconductive devices -- Research, Cardiography -- Research, Resonators -- Research, Biomagnetism -- Research, Biomagnetism -- 2002 AD, Cardiography -- 2002 AD, Diagnostic equipment (Medical) -- 2002 AD, Resonators -- 2002 AD, Superconductive devices -- 2002 AD, Business, Electronics, Electronics and electrical industries
Abstract

It is shown that a first-order portable HTS gradiometer that uses substrate resonator rf SQUIDs can be used for development of commercial magnetocardiographic (MCG) systems.

Published
2003

11. An insight into voltage-biased superconducting quantum interference devices

Author

Liu, Chao, Zhang, Yi, Mück, Michael, Krause, Hans-Joachim, Braginski, Alex I., Xie, Xiaoming, Offenhäusser, Andreas, Jiang, Mianheng, and Justus Liebig University Giessen

Subjects
ddc:530
Abstract

We experimentally studied two important parameters of helium-cooled superconducting quantum interference devices (SQUIDs) in the voltage bias mode: the dynamic resistance Rd and the flux-to-current transfer coefficient ?i/?phi, with different junction shunt resistors RJ. We investigated a voltage-biased SQUID using the direct readout current-to-voltage converter scheme involving an operational amplifier. At higher RJ, the flux-to-voltage conversion coefficient ?V/?phi becomes sufficiently large to effectively suppress the room-temperature amplifier´s noise without any need for additional feedback circuits. The McCumber parameter limits the rise of ?V/?phi. We discuss the performance of voltage-biased SQUIDs at different effective McCumber parameters.

Published
2012
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12. Analysis of a dc SQUID readout scheme with voltage feedback circuit and low-noise preamplifier

Author

Zeng, Jia, primary, Zhang, Yi, additional, Schmelz, Matthias, additional, Mück, Michael, additional, Krause, Hans-Joachim, additional, Braginski, Alex I, additional, Lee, Yong-Ho, additional, Stolz, Ronny, additional, Kong, Xiangyan, additional, Xie, Xiaoming, additional, Meyer, Hans-Georg, additional, Offenhäusser, Andreas, additional, and Jiang, Mianheng, additional

Published
2014
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16. Flux modulation scheme for direct current SQUID readout revisited.

Author

Tao Hong, Hai Wang, Yi Zhang, Krause, Hans-Joachim, Braginski, Alex I., Xiaoming Xie, Offenhäusser, Andreas, and Mianheng Jiang

Subjects
FLUX (Energy), FREQUENCY modulation detectors, ELECTRONIC amplifiers, ELECTRIC currents, ELECTRIC transformers
Abstract

The flux modulation scheme (FMS) is the standard readout technique of dc SQUIDs, where a step-up transformer links the SQUID to the preamplifier. The transformer's primary winding shunts the SQUID via a large capacitor while the secondary winding connects it to the preamplifier. A modulation flux having a frequency of typically 100 kHz generates an ac voltage across the SQUID, stepped up by the transformer. The SQUID with FMS is customarily operated in the current bias mode, because a constant dc bias current flows only through the SQUID due to the capacitor isolation. With FMS, however, the transformer ac shunts the SQUID so that in reality the operating mode is neither purely current-biased nor voltage-biased but rather nominal currentbiased or "mixed biased." Our objective is to experimentally investigate the consequences of ac shunting of the dc SQUID in FMS and the transformer's transfer characteristics. For different shunt values we measure the change in the SQUID bias current due to the ac shunt using another SQUID in the two-stage readout scheme, and simultaneously monitor the SQUID output voltage signal. We then explain our measurements by a simplified graphic analysis of SQUID intrinsic current-voltage (I-V) characteristics. Since the total current flowing through the SQUID is not constant due to the shunting effect of the transformer, the amplitude of SQUID flux-to-voltage characteristics V(U) is less as compared to the direct readout scheme (DRS). Furthermore, we analyze and compare V(U) obtained by DRS and FMS. We show that in FMS, the transfer characteristics of the SQUID circuit also depend on the isolation capacitance and the dynamic resistance of the SQUID. [ABSTRACT FROM AUTHOR]

Published
2016
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20. Parameter tolerance of the SQUID bootstrap circuit

Author

Zhang, Guofeng, primary, Zhang, Yi, additional, Dong, Hui, additional, Krause, Hans-Joachim, additional, Xie, Xiaoming, additional, Braginski, Alex I, additional, Offenhäusser, Andreas, additional, and Jiang, Mianheng, additional

Published
2011
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