Key device/circuit technologies for realizing a 28nm-node atom switch programmable logic (AS-PL) have been developed. An advanced polymer solid-electrolyte (PSE) reduces set voltage down to 1.6 V ...while ensuring ON-state and OFF-state reliabilities under current and voltage stress at 125°C. A fine-grain redundancy in a cross-bar array also contributes to reduce supply voltage by 6%. A routing-based wear leveling improves programming cycles by nine times. The developed technologies allow us to design the 28nm-node AS-PL with a 32% higher performance and 11% lower power.
This paper describes two subjects, both aimed at the industrialization of Nb 3 Al conductors. One is the metastable solid-solution-strand restacking method, which is expected to be a low-cost ...Cu-stabilization method compared with the electroplating technique. In this paper, we mainly focus on recent efforts toward long-length production. The key point here is an improvement of the contact between the Cu tube and the restacked original strands. The second subject is the first attempt at "constant voltage" control in the continuous rapid-heating and quenching operation for 300-m-class precursor wire. With constant current control, changes in the diameter of the wire lead to variations in power per unit volume, so that the processing temperature changes. With constant voltage control, changes in diameter of the wire do not lead to changes in the power per unit volume, so that the processing temperature does not change and thus the uniformity of the longitudinal performance is improved.
This paper focuses on the magnetization characteristics of technical Nb3Al conductors, in particular the minimization of their hysteresis loss and low-field instability. Unlike the case of Nb3Sn wire ...fabrication, the Nb3Al wire is fabricated by a phase transformation process, in which it is believed that the Jc properties of the transformed Nb3Al phase do not depend on the filament size or shape, but rather are principally controlled by the rapid heating and quenching or transformation conditions. However, the rapid heating and quenching process forces us to use high-melting-point metals like niobium as the matrix. The use of Nb strongly affects the magnetization because of its superconductivity in low fields. In this paper, the magnetization properties of several kinds of technical Nb3Al conductors, including Ta matrix wires, were studied. The use of Ta was effective in suppressing low-field instability. In addition, we propose a new process to further minimize the filament diameter by a re-stacking (RS) method, whereby the rapidly quenched strands are re-stacked into a stabilizing material tube and co-drawn. This process leads to a very fine multifilamentary structure with a filament diameter of less than 15 mum, thereby substantially reducing the magnetization, as compared with high-performance Nb3Sn wires, e.g. RRP Nb3Sn wire. The +/- 3 T hysteresis loss of the RS Nb3Al conductor was 370 mJ cm-3 and the non-Cu Jc (12 T, 4.2 K) of the conductor was 1350 A mm-2. These values meet the ITER strand specification.
For the first time, a 40nm-node, 2× logic density, 3.8× operation speed, and 3× power efficient, nonvolatile programmable logic (NPL) is demonstrated by using Cu atom switch for configuration ...switches. The switching characteristics of the atom switch are kept in scaling down to 64/32nm device area, and an improved PSE reduces set voltage while keeping low leakage current, enabling core transistors to select the atom switches. The developed 40nm NPL is a strong candidate for the next wave of energy-efficient computing.
We have been developing Nb 3 Al high-field accelerator magnets with the aim of upgrading the luminosity of the Large Hadron Collider. In this program, four kinds of Ta-matrix Nb 3 Al strands with ...slightly different cross-sectional structures (K1, K2, K3 and K4 strands) were designed and fabricated. The non-copper J c values of these strands were 700-800 at 15 T and 4.2 K. The cabling work of these strands was performed at Fermilab, and the superconducting properties of the cables were studied using the extracted strands from the cables. In this paper, we report on the fabrication experience for the strands and cables. The results obtained from this study are also presented.
The strain dependence of not only the critical current (Ic) but also the n-value in technical Nb3Al wires prepared with the rapid-heating, quenching and transformation (RHQT) method has been measured ...with the modified Walters spring (WASP), which allows us to measure the voltage-current relation down to less than the 0.1 muV cm-1 criterion, an important requirement in view of the applications like NMR spectroscopy operated in a persistent current mode. The measurement was made in fields up to 17 T and at 4.2 K, for several kinds of Nb3Al wires, including stabilized wires and wires with a tantalum matrix.
Research and development of Nb{sub 3}Al strands and cables for a high field accelerator magnet is ongoing under the framework of the CERN-KEK collaboration. In this program, new Ta-matrix Nb{sub 3}Al ...strands were developed and their mechanical properties and superconducting properties were studied. The non-Cu J{sub c} values of these strands were 750 {approx} 800 A/mm{sup 2} at 15 T and 4.2 K. Using these strands, test fabrication of 27-strand Rutherford cable was carried out in collaboration with NIMS and Fermilab. The properties of the strands extracted from the cable were examined and it was found that there was no degradation of the superconducting properties of the strands. In this paper, we report the fabrication of the strands and the cable in brief and present some of the results obtained by studying their properties.
Observations of fractured cross sections, which are frequently used to determine the grain size distribution in Nb 3 Sn, cannot be performed for Nb 3 Al since transgranular fracture is the dominant ...fracture mode. Instead, we have evaluated the grain size of Nb 3 Al using electron backscatter diffraction (EBSD). To check the validity of EBSD analysis for A15 grain structures, bronze-route Nb 3 Sn filaments were also examined by EBSD. The deformation-and-transformation of bcc supersaturated-solid solution Nb(Al) ss was found not only to homogenize and refine the grain size of the resultant Nb 3 Al but also to increase a ratio of high angle grain boundaries to low angle grain boundaries. The texture studies were made by pole figure works: the Nb(Al) ss retains a 〈110〉 fibrous texture as well as the filament barrier (Nb, Ta) does. The transformed Nb 3 Al also has the weak 〈110〉 fibrous texture, whereas Nb 3 Sn has almost never texture. A clear relationship between Jc and the inverse of grain size was not observed.
