Through the collaboration of the Japan Atomic Energy Agency and High Energy Accelerator Research Organization, the Japan Proton Accelerator Research Complex (J-PARC) has been constructed. The prime purpose is to use the various secondary particle beams such as neutrons, mesons and neutrinos produced in proton-nucleus reactions. One of the facilities that has already been completed is a materials and life-science experimental facility (MLF) where materials and biological structures are analyzed by neutron beam-scattering experiments. In the MLF, a spallation neutron source that provides a high-intensity pulse neutron with low-order meV energy for scattering experiments has been completed, and has successfully produced the desired neutrons. Neutrons produced by spallation reaction have high-order MeV energy, and the high-energy neutron is then transformed to meV-order energy by passing it through a supercritical hydrogen moderator. Therefore, a cryogenic hydrogen system is equipped in the spallation neutron source system. This paper describes the first operation results of the cryogenic hydrogen system.
It is expected that liquid hydrogen (LH2) will be utilized for energy transportation and storage. The LH2 maintained in storage tanks is capable of generating electric power for a long time through fuel cells (FCs) without emission of carbon dioxide (CO2), and can cool high-temperature superconducting (HTS) machines, such as SMES and HTS cable, as well. We propose a hybrid energy transportation system composed of LH2 transfer pipeline, a FC system and HTS cable. We studied the power efficiency of the hybrid system and the pipeline design. We estimated the loss in the LH2 transfer pipeline with HTS cable and optimized the pipeline design. It was found that the hybrid energy transportation system has lower loss than conventional electric power cable. Since this system can transport not only LH2, but also large electric power with small loss, twice the amount of electric power can be supplied when large power load is required at peak times.
As a thermal property of MgB2 wires, we observed the propagation velocity of a normal zone for those immersed in liquid helium. The normal zone propagation was initiated by a resistive heater and the propagation velocity was estimated from the response of voltage difference bet