Abstract. Magnetic refrigeration which is based on the magnetocaloric effect of solids has the potential to achieve high thermal efficiency for hydrogen liquefaction. We have been developing a magnetic refrigerator for hydrogen liquefaction which cools down hydrogen gas from liquid natural gas temperature and liquefies at 20 K. The magnetic liquefaction system consists of two magnetic refrigerators: Carnot magnetic refrigerator (CMR) and active magnetic regenerator (AMR) device. CMR with Carnot cycle succeeded in liquefying hydrogen at 20K. Above liquefaction temperature, a regenerative refrigeration cycle should be necessary to precool hydrogen gas, because adiabatic temperature change of magnetic material is reduced due to a large lattice specific heat of magnetic materials. We have tested an AMR device as the precooling stage. It was confirmed for the first time that AMR cycle worked around 20 K.

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Photoemission spectra of the AI-Cu-Fe quasicrystal with the icosahedral phase were studiedat roomtempcramre. The lineshaproithcover~llobrervedspenntmislikea large peakonaplatcaucut-oiiat €,.The largepeakobrervedatabour4rV bclowEFrems 10 originate maid) from the 3d stale of Cu atoms. Thc bump was observed at about 1 eV below EF. The high resolutionexpenmen1 shoucd ananomalousvalley at E, in theelectronic density of stater. This means that the dip at E f in the DOS has a half-width 0.3-0.4 dV and that its depth 1s 70% of the value for a no-dip case Recently, an AI-Cu-Fe alloy system was found to have a stable i-phase with high quasicrystallinequality[1,2,3]. Usingthisquasicrystal, itwasreportedthat themagnetic susceptibility is proportional to Tz. This fact suggests a sharp dip (valley-like) structure intheelectronicdensityofstates(~os)attheFermienergy(E~),sincethe Ttdependence occurs due to the Pauli paramagnetism [3,4]. The dip structure was interpreted in terms

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Synopsis(I) Reduction of molten iron oxide and Fe0 bearing slag by H2 Ar plasma was studied using water cooled Cu crucible. The sample weights were 25 to 75g, the flow rate of mixture-gas was 20 1/mm n and DC electric power of plasma was 8.3 kW. Results obtained were as follows:(1) The reduction of molten iron oxides proceeds linearly with time and the reaction rate is proportional to the partial pressure of atomic hydrogen. Therefore, it is considered that the rate determining step is the chemical reaction between Fe0 and the atomic hydrogen formed by thermal dissociation in the plasma.(2) The rate of reduction of Fe0 bearing slag is lower than that of molten iron oxide and is proportional to the Fe0 concentration in slag. It is presumed that the reduction rate is controlled by both the chemical reaction rate of Fe0 with atomic hydrogen at the gas-solid interface and the mass transport rate of Fe0 across the boundary layer between the interface and the molten slag bulk.(3) The reduction of molten iron oxide and Fe0 bearing slag by H2 Ar plasma takes place only on the cavity formed at the surface of melt by the momentum of plasma jet gas.(II) Continuous melting of pre-reduced ore powder, obtained by a fluidized bed reduction was examined using MgO crucible and H2 Ar plasma.Following results were obtained:(1) Carry-over loss of the pre-reduced ore powder during the melting in plasma arc furnace was small, when the condition of powder feeding and plasma arc were properly chosen.(2) Reduction of Fe0 in slag, accompanied in fed material, by H2-Ar plasma, could be described by a simple model of continuous melting and reduction, based on experimental results of the reduction of Fe0 bearing slag as described (1-2).With this model, the rate of reduction during continuous melting was determined.

Magnetic refrigeration which is based on the magnetocaloric effect of solids has the potential to achieve high thermal efficiency for hydrogen liquefaction. We have been developing a magnetic refrigerator for hydrogen liquefaction which cools down hydrogen gas from liquid natural gas temperature and liquefies at 20 K. The magnetic liquefaction system consists of two magnetic refrigerators: Carnot magnetic refrigerator (CMR) and active magnetic regenerator (AMR) device. CMR with Carnot cycle succeeded in liquefying hydrogen at 20K. Above liquefaction temperature, a regenerative refrigeration cycle should be necessary to precool hydrogen gas, because adiabatic temperature change of magnetic material is reduced due to a large lattice specific heat of magnetic materials. We have tested an AMR device as the precooling stage. It was confirmed for the first time that AMR cycle worked around 20 K.

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