Abstract-The European Josephson arbitrary waveform synthesizer (JAWS) project addresses the lack of instrumentation and knowledge for accurate and traceable measurement and generation of alternating (AC) voltage with arbitrary waveforms. The objective is to develop a standard based on a JAWS, a precise instrument that links the generated voltage to the Josephson effect, which in turn relates voltage to fundamental constants and frequency. The standard aims at synthesized voltages up to 10 mV, frequencies up to 10 kHz and uncertainty smaller than 100 V/V as a first step. This paper reports on the progress in developing the key components for JAWS.

A fully automated system has been developed for voltage calibrations where fast programmability and extremely low uncertainties are required. This system is based on a binary Josephson junction array with a smallest segment of one single junction. As an important application, the linearity of the 10 mV range of a digital nanovoltmeter was determined with a standard uncertainty better than 1 nV. As a further application of the fast programmability of the binary Josephson system, the standard uncertainty of voltage ratios measured by an -digit digital voltmeter in quantum Hall measurements was measured to be 10 × 10−9.

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2G HTS wires need substantial development to allow ac applications with acceptable losses in ac magnetic fields perpendicular to the tape plane. Filament transposition is necessary to avoid large coupling currents and also to insure a uniform current flow through all the filaments, both of which are essential to minimize ac losses. Conductor twisting solves only the first part of the problem and is not really practical in a tape-shaped wire needing to be wound for instance into compact coils of various shapes. We set out to evaluate a new two-dimensional transposition approach for striated, multifilamentary 2G HTS wire. The new concept uses a so-called transposition zone, located along a linearly striated conductor. In this 7-10 cm long zone all filaments are transposed. The repeat distance of this transposition zone can be as short as 10 m or as long as 100 m, depending on the particular superconducting device and the anticipated ac magnetic fields. In this project a successful transposition approach with acceptable losses was developed. Both the striation method using lateral translations, and sound junction types using different materials, were demonstrated.Index Terms-AC loss, filament transposition, high temperature superconductors, YBa 2 Cu 3 O 7 x .