TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)
Online ISSN : 1880-0408
Print ISSN : 0389-2441
ISSN-L : 0389-2441
Search
Advanced search
OR
Browse
Search
Volume 41, Issue 2
Displaying 1-4 of 4 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
Preface
Review Article
  • Liquid and Slush Hydrogen: Its Application and Technology Development
    Katsuhide OHIRA
    2006 Volume 41 Issue 2 Pages 61-72
    Published: 2006
    Released on J-STAGE: February 15, 2007
    DOIhttps://doi.org/10.2221/jcsj.41.61
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Since liquid hydrogen has a high specific impulse as fuel for rockets, its technology has been developed in connection with space technology programs. On the other hand, with the recent advance of technologies such as fuel-cell vehicles and stationary fuel-cell systems, liquid hydrogen is also expected to be used as an efficient means of transporting and storing hydrogen used as a source for clean energy. Slush hydrogen is a two-phase solid-liquid cryogenic fluid consisting of solid hydrogen particles in liquid hydrogen. Compared with liquid hydrogen, the density and cryogenic heat capacity of slush hydrogen with a solid fraction of 50% increase by 16% and 18%, respectively. Various applications of slush hydrogen are anticipated such as fuel for reusable space shuttles and fuel cells, and as a more efficient means of transporting and storing liquid hydrogen. This paper describes the applications and technology developments of liquid and slush hydrogen.
    View full abstract
    Download PDF (2475K)
Originals
  • Efficiencies of a Pulse-tube Refrigerator and Heat-driven Thermoacosutic Cooler
    Yuki UEDA, Tetsushi BIWA
    2006 Volume 41 Issue 2 Pages 73-80
    Published: 2006
    Released on J-STAGE: February 15, 2007
    DOIhttps://doi.org/10.2221/jcsj.41.73
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    We discuss the heat flow and work flow of an orifice pulse-tube refrigerator and a heat-driven thermoacoustic cooler consisting of a single looped tube. It is shown that, while the orifice of the orifice pulse-tube refrigerator is essential for increasing the cooling power, it decreases the efficiency because of the dissipation introduced by itself. It is also shown from the energy flow diagram that dissipation of the work flow inherently occurs in the heat-driven thermoacoustic cooler, resulting in a reduction in efficiency. We present that these unwanted dissipations would be avoided by the addition of a feedback path for the work flow. The modified refrigerator and the cooler would achieve efficiencies much higher than those of the original ones, especially at noncryogenic temperatures.
    View full abstract
    Download PDF (3796K)
  • Improvement of Superconducting Antenna and Filter Properties using Laser Trimming
    Naoto SEKIYA, Satoshi ONO, Kensuke NAKAJIMA, Atsushi SAITO, Satoru HIR ...
    2006 Volume 41 Issue 2 Pages 81-86
    Published: 2006
    Released on J-STAGE: February 15, 2007
    DOIhttps://doi.org/10.2221/jcsj.41.81
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Improvements in superconducting device characteristics using laser-etching trimming is examined. A KrF excimer laser (248 nm) was used. As an example, improving the bandwidth of a superconducting patch antenna with gap-coupled resonators and that insertion loss of a 3-pole hairpin-type superconducting filter were studied. We found that laser-etching trimming is quite useful for improving the antenna and filter properties; increasing the bandwidth and reducing return loss with the antenna, and reducing loss with the filter.
    View full abstract
    Download PDF (1308K)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top