[en] Spin (accompanied by mass) flows can be induced magnetically in its 'ferromagnetic' spin-polarized superfluid ³He A₁ phase. Observations have been made by applying magnetic field gradients across a spin filter and measuring the induced pressure gradient. There are issues which remain unresolved. An ideal static magnetic fountain effect has not been seen. The observed effect decays with a characteristic relaxation time. The relaxation time jumps by a factor of 2 near the middle of the A₁ phase. The presence of A₁/A₂ phase interface has been speculated to cause the jump. The measured relaxation time increases with the applied field up to 1.4 T. The origins of the temperature and field dependence are not understood. Planned experiments to probe these issues are described

No abstract available

[en] A mass superflow in A₁ phase carries both fully polarized nuclear spin flow and zero entropy simultaneously. The second sound in A₁ is then a hybrid spin/entropy wave propagation. The authors have studied the spin/entropy wave propagation in fields up to 5 T between 10 and 30 bar. When A₁ makes transition into the superfluid A₂ phase, the spin/entropy wave is expected to disappear abruptly. Unexpectedly the authors observe that there is a open-quotes criticalclose quotes region within A₁ phase over which the attenuation gradually increases. The observation might be an evidence for presence of minority spin pairs in A₁. From the measured velocity of spin/entropy wave, the authors determinde the superfluid to normal component density ratio. In the Ginzburg-Landau region of their measurement close to the transition temperature, the superfluid fraction can be simply related to the expansion coefficients, β_i, of free energy in terms of order parameter. Using their results and the phase diagram, the authors have extracted β₂₄=(β₂+β₄) and β₅. The strong coupling corrections so obtained to the expansion coefficients are in agreement with theory

[en] The spin/entropy wave propagation was observed in a cylindrical resonant cavity filled with superfluid ³He A₁ phase in 2 T and 22.9 bar. Oscillating superleak transducers were used with Nuclepore membranes (3 μm pores) as active elements. When the drive is increased to a sufficiently high level, saturation in the resonant response is observed. The observed non-linear response will be interpreted in terms of critical velocity. The effects of superfluid fraction anisotropy on the spin/entropy wave propagation are currently under study by changing the relative orientation between the magnetic field and the sound propagation directions. Results of these studies will be reported

[en] Hull wastes and some scrapped equipment are typical radioactive wastes generated from reprocessing process in Tokai Reprocessing Plant (TRP). Because hulls are the wastes remained in the fuel shearing and dissolution, they contain high radioactivity. Japan Nuclear Cycle Development Institute (JNC) has started the project of Hull Waste Treatment Facility (HWTF) to treat these solid wastes using compaction and incineration methods since 1993. It is said that Zircaloy fines generated from compaction process might burn and explode intensely. Therefore explosive conditions of the fines generated in compaction process were measured. As these results, it was concluded that the fines generated from the compaction process were not hazardous material. This paper describes the outline of the treatment process of hulls and results of safety evaluation

[en] The authors measured the decrease of ³He fourth sound quality factor in packed 3, 1 and 0.3 micron powders and in sintered silver powder when the surfaces are coated with ⁴He. The decrease in Q results from the increase in specularity (S) and slippage of normal fluid at the wall surfaces. The authors deduce S from Q data. S does not change up to about 1.5 layers of ⁴He, but beyond this coverages S increases rapidly and becomes unity near 3 layer coverage. As S increases, the measured effective superfluid fraction increases. When the ³He fluid pressure is increased to greater than some pressure depending on powder, the Q and the superfluid fraction return to the pure ³He values. Qualitative features are similar to Thole and Parpia except that only very small, if any, hysteresis is observed in the authors pressure change data

[en] A compact interdigital capacitor is developed as a level detector of solid ⁴He. The capacitor consists of 38 interlaced 50 μm wide and 3.8 mm long gold films separated by 50 μm and deposited onto a flat 5x5 mm² sapphire substrate. The background capacitance is 6.5 pF. The capacitance change is 1.3x10^-3 pF/mm of solid ⁴He height change. A height change of 10 μm is detectable. Observations at 1.2 K in a 6.7x8.7x9.1 mm³ cell show over pressures (measured with a low temperature strain gauge) up to 25 mbar prior to nucleation of solid. The solid height may be controlled by varying heat applied to a pressure bomb cooled to 77 K

No abstract available

[en] The superfluid fraction of ³He A₁ phase is computed from measurements of the velocity of spin/entropy waves induced in a cylindrical chamber, for two different directions of the magnetic field: parallel and perpendicular to the axis of the chamber. The ratio of the superfluid fractions in the parallel and perpendicular orientations is 1.85, and does not depend on the field between 1 and 5 Tesla. We adapt a theoretical texture model to account for the superfluid flow, and the results are consistent with the above ratio and direct estimates of superfluid velocity

[en] An experimental and theoretical investigation of the electrostatic wave propagating across the magnetic field at frequencies around the ion-ion hybrid resonance is presented. Firstly, the dispersion relation for the warm electron mode (ω/ksub(parallel to) << upsilonsub(e)) is measured in a simple toroid plasma, which is composed of helium and neon ions, with the ion concentration ratio controlled. The experimental results and the calculations reveal that even a small fraction (approx. 1%) of the minority concentration leads to an additional cutoff and hybrid resonance near the minority-cyclotron-resonance frequency. Secondly, the ion-ion hybrid resonance cone of the warm electron mode is observed for the first time. The dependence of the resonance cone angle on the frequency and the ion concentration ratio is observed to agree with the theoretical predictions. (author)