Abstract
Hydrogen was first liquefied in 1898. However, more than a half-century, liquid hydrogen was liquefied in small quantities in a few cryogenic laboratories in the world. But now the industrial importance of liquid hydrogen is well recognized. In U.S.A. and Europe, it is produced and utilized in large quantities in chemical and nuclear propulsion, production of heavy water, bubble chamber in nuclear study and some other fields of science and industry. In our country, liquid hydrogen industry is still in its infancy, but quite recently 75cm liquid hydrogen bubble chamber and its refrigeration system having the capacity of 1kW at 20°K region have installed in the University of Tokyo. In this paper, the trends of liquid hydrogen industry in the world are reviewed and also comments are described in some possible utilizations of liquid hydrogen.
