| 1. |
- Ahlers, F.J., et al.
(författare)
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The EMRP project GraphOhm- Towards quantum resistance metrology based on graphene
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - 0589-1485. - 9781479952052 ; , s. 548-549, s. 548-549
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Konferensbidrag (refereegranskat)abstract
- A new joint research project (JRP) integrating metrology institutes and universities from nine countries is aimed at realization of a new generation of standards for quantum resistance metrology. The project exploits graphene's properties to simplify operation of standards without compromising the unprecedented precision delivered by semiconductor quantum Hall devices. Higher operating temperatures (above 4.2 K, and up to 8 K) and together with lower magnetic fields (below 5 T, and potentially down to 2 T) will lead to a significantly improved and cost-saving dissemination of intrinsically referenced resistance standards to all end-users relying on electrical measurements.
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| 2. |
- Hammarqvist, Maria, 1975, et al.
(författare)
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Improvement of frequency response for a zero-flux current measuring system
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - 0589-1485. - 9781479952052 ; , s. 618-619
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Konferensbidrag (refereegranskat)abstract
- Magnetic zero-flux current transformers are widely utilized to measure AC and DC electrical currents. To improve the AC characteristics between 10 Hz and 100 kHz, a method is proposed to evaluate adjustments in the circuitry; increase of the amplification in the AC feed-back circuit and introduction of an external coaxial read-out shunt resistor. The method is generally applicable and includes a coaxial current path within the entire reference system and traceability to national standards. The AC working range is extended from about 1 kHz to about 3 kHz. Outside the nominal AC working range, the scale factor variation is reduced from 45 % to 3.5% and the phase angle error offset changes from ca 5.8 μs to below 0.3 μs.
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| 3. |
- Andersson, Bengt Olof, et al.
(författare)
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The reference step method for DC voltage at 1 mV and 10 mV
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - : Institute of Electrical and Electronics Engineers Inc.. - 9781479952052 ; , s. 520-521
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Konferensbidrag (refereegranskat)abstract
- We have investigated the performance of a method called the Reference Step Method at low voltage levels. The method has been evaluated earlier at voltage levels from 0.1 V to 1 kV with excellent results. The advantages of this method are that it uses commonly available equipment and can be fully automated. We have made comparisons with three other low-voltage methods and the differences show that the uncertainties can be less than 30 μV/V at 1 mV and 3 μV/V at 10 mV, making it possible to use this method to perform automated calibration of calibrators with sufficient accuracy for calibration of high-end instruments.
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| 4. |
- Bergsten, Tobias, et al.
(författare)
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An active filter for Delta-Sigma modulated Josephson waveforms
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - : Institute of Electrical and Electronics Engineers Inc.. - 9781479952052 ; , s. 518-519
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Konferensbidrag (refereegranskat)abstract
- We present an active low pass filter constructed for Delta-Sigma modulated Josephson waveforms. The filter has a fifth order Butterworth characteristic with high input impedance and stable passband performance, including dc. We present results from frequency response, input impedance characteristics, passband ac-dc measurements and spectra of a Delta-Sigma modulated sine wave from a programmable Josephson voltage standard.
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| 5. |
- Eklund, Gunnar, et al.
(författare)
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Progress towards an impedance bridge using two programmable Josephson voltage standards
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - : Institute of Electrical and Electronics Engineers Inc.. - 9781479952052 ; , s. 224-225
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Konferensbidrag (refereegranskat)abstract
- We describe the work towards a setup of a low frequency 'Josephson impedance bridge' based on programmable Josephson voltage standards. Tests of ac voltage synthesis and dc voltage measurements of the two programmable Josephson standards have been performed including a direct Josephson dc voltage comparison.
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| 6. |
- Elg, Alf Peter, et al.
(författare)
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Traceability and characterization of a 1000 kV HVDC reference divider
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - 9781479952052 ; , s. 780-781
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Konferensbidrag (refereegranskat)abstract
- This paper presents the characterization of a resistive HVDC reference divider and methods to establish a traceability. The divider is designed for use as a laboratory reference for calibration of HVDC measuring systems up to 1000 kV. Targeting a measurement uncertainty of 20 ppm at full voltage has put a focus on the temperature coefficients of the resistors, elimination of humidity dependence and control of leakage currents in the high voltage arm.
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| 7. |
- Hallstrom, J., et al.
(författare)
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Performance of a modular wideband 1000 kV HVDC reference divider
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - 9781479952052 ; , s. 782-783
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Konferensbidrag (refereegranskat)abstract
- This paper describes the performance of a wideband HVDC reference divider. The divider concept is a shielded modular divider and it is intended for traceable calibration of HVDC measuring systems up to 1000 kV in customers' laboratories. The first priority in the design was the accuracy of HVDC measurements. In addition, the divider was designed to have wide bandwidth, both to enable measurement of ripple voltages and to prevent damage during possible flashovers. © 2014 IEEE.
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| 8. |
- Högas, Marcus, et al.
(författare)
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An analytic solution of the magnetic field and inductance in the main region of a coaxial short circuit
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - : Institute of Electrical and Electronics Engineers Inc.. - 9781479952052 ; , s. 276-277
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Konferensbidrag (refereegranskat)abstract
- In this paper an analytic solution of the magnetic field and inductance in the main region of a coaxial short circuit is presented. The magnetic field solution is constructed using a mode matching technique when solving the magnetic field differential equation and corresponding boundary conditions. By integrating the absolute square of the magnetic field solution the inductance is obtained.
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| 9. |
- Janssen, Tjbm, et al.
(författare)
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Breakdown of the quantum Hall effect in graphene
- 2012
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - 0589-1485. - 9781467304399 ; , s. 510-511
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Konferensbidrag (refereegranskat)abstract
- We present experimental details on the carrier density dependent breakdown current in epitaxial graphene grown on SiC. We show that in this system even at very low carrier densities and moderate temperatures it is still possible to have a breakdown current large enough for metrologically accurate quantum Hall resistance measurements. This work paves the way for a simple bench top/turnkey quantum resistance standard.
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