Regis Pinheiro Landim, Waldemar Guilherme Kürten Ihlenfeld
DC Voltage Linearity Measurements and DVM Calibration with Conventional and Programmable Josephson Voltage Standards

Traditional calibration of dc voltage high accuracy digital voltmeters (DVMs) using conventional and Programmable Josephson Voltage Standards at INMETRO show improvements between 73.7 % and 98.3 % when compared with a regular calibration technique. Some calibration results as well as DVM linearity and gain drift analysis (up to 10 V range) are presented and discussed in this paper.

Umberto Pogliano, Bruno Trinchera, Danilo Serazio
Traceability for accurate resistive dividers

Resistive dividers find application in instrumentation because they allow fast and precise scaling-down of the applied signal input to an appropriate level of the processing electronics. Furthermore, among the applications where both wideband and accuracy requirements are demanding, resistive dividers employed as fixed-voltage ratio standards are widely used. Recently, at INRIM, coaxial voltage dividers suitable to be used in specific tasks of EU and National co-founded projects have been developed. Series-parallel type of dividers have been studied and built. Besides, methods for adjusting and calibrating their ratio, frequency response and phase difference have been analysed and experimented. Some aspects of the developed traceability chain and some examples of calibration results are given.

Dragana Popovic Renella, Sasa Dimitrijevic, Sasa Spasic, Radivoje S. Popovic
High-Accuracy Teslameter with Thin Three-Axis Hall Probe

The new digital teslameter system incorporates a 3-axis Hall probe, analog electronics based on the spinning-current technique, 24-bit analog-to-digital converter, computer, and 7-digit touch-screen display. The Hall probe is a single silicon chip with monolithically integrated horizontal and vertical Hall magnetic sensors and a temperature sensor. The Hall sensor chip is encapsulated in a robust ceramic package, a version of which is only 250μm thick. The spinning-current eliminates most of the Hall probe offset, low-frequency noise, and the planar Hall voltage. The errors due to the Hall element non-linearity and the variations in the probe electronics temperatures are eliminated by a calibration procedure based on a three-variable second-order polynomial. The errors due to the angular errors of the Hall probe are eliminated by a calibration of the sensitivity tensor of the probe. These new developments resulted in a teslameter that can measure magnetic field vectors from about 1μT to 30T, with the spatial resolution 100 μm, magnetic resolution ±2ppm of the range, the accuracy ±0.0001% of reading + 0.001% of range, temperature coefficient less than 5ppm/°C, and angular errors less than 0.1°.

Pasquale Arpaia, Marco Buzio, Ernesto De Matteis, Olaf Dunkel, Stephan Russenschuck
Experimental characterization of a rotating coil transducer for local multipole scanning

Recent compact accelerator developments for biomedical care and physics research has brought the need for small-aperture magnets as well as strongly bent magnet with curvature radii of less than 5 meters. Traditional transducers for magnetic measurements are not mechanically adaptable for local magnetic field measurements. In this paper, a new rotating coil transducer with compact design is proposed for local, transversal multipole scanning in straight and curved magnets. The requirements, design, prototyping, and the results of magnetic and electrical compatibility tests are presented.

K. Buhagiar, Philippe Lerch, A. Gabard, Marco Buzio, Stephane Sanfilippo, A. Foussat
Magnetic Survey of Large Magnets: a 1 to 5 scale model system

A tokamak includes large scale magnets like poloidal and toroidal field coils. Shape deformations and/or assembly errors will lead to error fields in the final configuration, which is obtained by arranging several coils of both types. In the framework of the ITER tokamak project, we are developing a magnetic measurement system capable to record, at room temperature, the current center line (CCL) of the winding pack of the toroidal superconducting field coils. The knowledge of the CCL will be compared with survey data collected during manufacturing and assembly, and possibly be used as input at the stage of assembling the TF coils in the pit of the machine. In order to validate our approach, we built a 1:5 scale TF coil single filament test platform. This contribution describes our approach and presents results obtained with this laboratory prototype.