IEEE Transactions on Applied Superconductivity 

About: IEEE Transactions on Applied Superconductivity is an academic journal published by IEEE Council on Superconductivity. The journal publishes majorly in the area(s): Superconducting magnet & Electromagnetic coil. It has an ISSN identifier of 1051-8223. Over the lifetime, 20205 publications have been published receiving 245854 citations. The journal is also known as: Institute of Electrical and Electronics Engineers transactions on applied superconductivity.

RSFQ logic/memory family: a new Josephson-junction technology for sub-terahertz-clock-frequency digital systems

Abstract: Recent developments concerning the rapid single-flux-quantum (RSFQ) circuit family are reviewed. Elementary cells in this circuit family can generate, pass, memorize, and reproduce picosecond voltage pulses with a nominally quantized area corresponding to transfer of a single magnetic flux quantum across a Josephson junction. Functionally, each cell can be viewed as a combination of a logic gate and an output latch (register) controlled by clock pulses, which are physically similar to the signal pulses. Hand-shaking style of local exchange by the clock pulses enables one to increase complexity of the LSI RSFQ systems without loss of operating speed. The simplest components of the RSFQ circuitry have been experimentally tested at clock frequencies exceeding 100 GHz, and an increase of the speed beyond 300 GHz is expected as a result of using an up-to-date fabrication technology. This review includes a discussion of possible future developments and applications of this novel, ultrafast digital technology. >

HTS Pancake Coils Without Turn-to-Turn Insulation

Abstract: This paper reports a study of HTS pancake coils without turn-to-turn insulation. Three no-insulation (NI) pancake coils were wound: each single and double pancake coil of Bi2223 conductor and one single pancake of ReBCO conductor. An equivalent electrical circuit for modeling NI coils was verified by two sets of test: 1) charge-discharge; and 2) sudden discharge. Also, an overcurrent test in which a current exceeding a coil's critical current by 2.3 times was performed, and analysed, to demonstrate that in terms of stability NI HTS coils outperform their counterparts. The new NI winding offers HTS coils enhanced performance in three key parameters: overall current density; thermal stability; and mechanical integrity.

Energy-Efficient Single Flux Quantum Technology

Abstract: Figures of merit connecting processing capabilities with power dissipated (OpS/Watt, Joule/bit, etc.) are becoming dominant factors in choosing technologies for implementing the next generation of computing and communication network systems. Superconductivity is viewed as a technology capable of achieving higher energy efficiencies than other technologies. Static power dissipation of standard RSFQ logic, associated with dc bias resistors, is responsible for most of the circuit power dissipation. In this paper, we review and compare different superconductor digital technology approaches and logic families addressing this problem. We present a novel energy-efficient single flux quantum logic family, ERSFQ/eSFQ. We also discuss energy-efficient approaches for output data interface and overall cryosystem design.

Energy-Efficient Superconducting Computing—Power Budgets and Requirements

Abstract: Large-scale computing system characteristics vary by application class, but power and energy use has become a major problem for all classes. Superconducting computing may be able to serve the needs of these systems significantly better than conventional technology. Recent developments in single flux quantum circuit technology for digital logic include variants with greatly improved energy efficiency. Concepts were investigated for computing systems capable of performance in the range from 1 to 1000 PFLOP/s. The concept systems were constrained to use existing commercial cryogenic refrigerators and Nb superconducting technology. In order to meet the performance goals, cache and main memory capable of operating at cryogenic temperatures will be required. Superconducting computing is shown to be potentially competitive on the basis of power and energy efficiency if key component technologies can meet specific goals. Potential advantages of superconducting computing are identified as well as areas requiring further development.

A 380 ps, 9.5 mW Josephson 4-Kbit RAM operated at a high bit yield

Abstract: We have developed a Josephson 4-Kbit RAM with improved component circuits and a device structure having two Nb wiring layers. A resistor coupled driver and sense circuit are improved to have wide operating margins. The fabrication process is simplified using bias sputtering, as a result, its reliability is increased. The RAM is composed of approximately 21000 Nb/AlO/sub x//Nb Josephson junctions, Mo resistors, Nb wirings, and SiO/sub 2/ insulators. Experimental results show a minimum access time of 380 ps and power dissipation of 9.5 mW. Maximum bit yield of 84% is obtained in minimum magnetic field of about 20 /spl mu/G. We confirm that most of fail bits are caused by trapped magnetic flux, and the RAM functions properly for 98% of the memory cells after measuring fail bit map several times. >