A two-stage-discharge ion source is proposed, in which a source plasma is produced through two stages of plasma production : first, an electron beam-plasma-discharge; second, a kind of hollow-cathode arc discharge. The first stage discharge produces a plasma containing abundant hot electrons. The plasma is then fed into the second stage, where -at a fairly low hydrogen gas pressure (P<4 m Torr)-a stable discharge is maintained by means of a cylinder electrode. This cylinder electrode, connected to its own dc power supply, effectively serves to increase the ion density and to flatten its radial distribution. The source plasma generated by the foregoing two-stage-discharge permits the extraction of a high current ion beam of increased beam perveance. When a cylinder electrode of 6.5 cm diameter was used, the plasma ion density measured in the circular area of 4 cm diameter in front of the ion extraction aperture array was of an order of 10¹² cm^-3 with a radial density fluctuation within ±0.1%. A description is given of this source, together with an analysis of the function of hot electrons on ion beam formation. A preliminary experiment on ion beam formation from this source plasma succeeded in obtaining a continuous hydrogen ion beam of 1.17 A at an extraction voltage of 30 kV, with use of multiaperture electrodes provided with seven apertures each of 9 mm diameter. The ion beam had a current density of 260 mA.DC/cm².

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The induction MHD generator using an alternating magnetic field is proposed. The characteristics of the machine are analyzed theoretically and also compared with those of the induction MHD generator using a traveling magnetic field.
Following conclusions are obtained for the fundamental characteristics of the present machine:
(1) This type of the machine is possibly operated not only as the generator but also as the pump or as the damper.
(2) The optimum condition for the maximum generator efficiency exists among the relations of the frequency, the fluid velocity and the inner core radius because of the eddy current loss due to an alternating magnetic field.
(3) The power ratio of the reactive power of the machine to the gross output power can be reduced to a much smaller value than that of the traveling wave MHD generator. Therefore, even in the case of the working fluid with a relative low electrical conductivity such as two-phase liquid metal flow with high void fraction, the acceptable power ratio can be expected.
(4) For the working fluid with higher electrical conductivity the skin effect is also able to be reduced to the acceptable level in the present machine, while it is a serious problem in the traveling wave MHD generator.

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The rotational stabilization has been proposed against the Rayleigh-Taylor instability of the imploding liquid metal liner. In this paper, the discussion is made on the possi-bility of the dynamic stabilization by applying the oscillating azimuthal magnetic field in addition to the axial field. In contrast to the rotational stabilization, the required (field) energy for this stabilization is also used for the liner driving or the plasma confinement. In the analysis, the liner subjected to the acceleration is assumed to be infinitely long, at rest and have the situation at the start of the implosion or turnaround. At turnaround, the existence of the plasma is taken into account. The perturbed motion of the liner is discussed with a linear stability analysis. Results are as follows:
(1) The dynamic stabilization at the start of the implosion is possible if the distance from the conducting wall to the liner outer surface is comparable with or less than the liner thickness.
(2) At turnaround, the stability is improved with decreasing the ratio of the plasma radius to that of the liner inner surface however the kink mode (m=1) cannot be suppressed.

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An analysis on the hydrodynamic instability of two-phase flow in parallel multichan-nels is conducted.
Occurrence of instabilities and their modes of oscillations can be evaluated by in-vestigating into a characteristic equation, its roots and composing channel transfer func-tions. It is also shown that a governing matrix is reduced to a diagonal one by using its eigenvalues, the oscillation modes being divided into N (number of channels) separate fundamental modes. Characteristics of each oscillation mode are given by examining corresponding characteristic equations.
The derived equations are applied for the prediction of oscillation modes of systems composed of a few slightly different channels. The analysis successfully predicts the modes which have been experimentally observed.

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Radio-cobalt and -manganese constitute more than 90% of the radionuclides in waste water released from various nuclear facilities. The adsorption characteristics of Mn ion on oxine-impregnated activated charcoal have been examined. In the adsorption, Mn ion will be in the chemical interaction with oxine on activated charcoal. Thus, the impre-gnation of oxine on activated charcoal considerably improves the adsorption properties of the latter, although the adsorption shows a strong pH-dependence. Two important parameters of the adsorption, initial adsorption rate constant and adsorption capacity, have been experimentally determined at various ion concentrations and have been dis-cussed in a comparison with those for Co ion.

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Magnetic susceptibility of UCl₅ showed a monotonic increase with lowering of tem-perature from room temperature to liquid helium temperature in spite of its dimer struc-ture. The magnetic susceptibility, the g-value and the electronic spectra were simul-taneously explained on the basis of crystal field model of the octahedral symmetry with a small C_2v, distortion.

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The self-diffusion coefficient of oxygen in single crystal thoria was determined at 1, 350°C in an ¹⁸O-enriched CO₂ atmosphere of oxygen partial pressure 3 × 10^-4 atm. The coefficient was close to the intrinsic self-diffusion coefficient determined in an oxygen atmosphere of 0.27 atm indicating the oxygen partial pressure independence. On the basis of the results, the mechanism was discussed for the conductivity data for thoria in the literature being due to the intrinsic diffusion and the extrinsic diffusion of oxygen ion and due to the intrinsic p-type electronic conduction predominant under high oxygen partial pressures.

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