An ion source of original concept, named "BPD Ion Source" is described, in which the source plasma is produced by an electron beam-plasma discharge. A hydrogen ion beam of 120 mA can be continuously ...extracted from the plasma in the direction of the electron beam at an extraction voltage of 30 kV through a single circular aperture of 8 mm dia. located at the bottom of the discharge chamber. The current density has reached 239 mA/cm
2
. The hot electrons contained in the source plasma facilitate the extraction of this intense ion beam. The normalized emittance of this source was observed to be 9.4×10
−7
m-rad with 100 mA beam extraction. The abundance ratio of the beam ion species and other characteristics are described and a discussion is presented on the possibility of scaling up for purposes of practical application.
In this paper, the frictional pressure drop in an isothermal liquid metal-gas two-phase flow through a rectangular channel with large width-to-height ratio is treated semiempirically for a NaK-N
2
...two-phase flow system.
The frictional pressure drop in the two-phase flow is compared with the following two reference values :
The comparison with the former reference value is necessary for the prediction of friction loss in a liquid metal MHD generator channel whose medium would be two-phase mixture.
The semiempirical analysis was performed assuming the two-phase mixture to be a continuous medium with its properties, e.g. viscosity and density, defined by void fraction and the velocity determined by the total mass flow rate.
In the region of low slip and density ratio ρ
g
/ρ
l
the frictional pressure drop in the two-phase flow appeared to be smaller than that due to the liquid flowing alone with the same velocity as that of the liquid in the two-phase flow.
The experiments have been undertaken with the NaK-N
2
two-phase mixture flowing through a rectangular channel (4 × 60 mm
2
).
Data were taken over the following parameter range:
NaK velocity: 5∼30 m/sec, Void fraction: 0∼70%
Density ratio: 0.006∼0.013, Quality: 0.07∼1.10%.
In an attempt to gain information on the propagation characteristics of pressure waves in a two-phase system consisting of gas and liquid, experiments were performed on a nonflowing air-water mixture ...in a range of pressures from 1.0 to 7.5 bar and void fractions from 0 to 60%. Stepwise pressure disturbancies were applied to a water column dispersed with rising air bubbles by bursting diaphragm. The pressure transients at several points down the fluid column were measured with strain gage type pressure transducers and recorded on magnetic tapes.
The nonlinearity of the pressure wave records was scarcely marked. The propagation velocity of pressure wave front down the fluid column was found almost independent of the magnitude of the pressure change applied, nor whether it was depressive or compressive. At higher void fractions where the flow regime became sluggy, the measured propagation velocities showed increasing deviation from the calculated values based on the nonslip homogeneous adiabatic model, though good agreements were obtained at lower void fractions of bubbly regime. Evidence was offered in disproof of the effect of heterogeneity due to slug regime as the preliminary step to attribute this discrepancy to the effect of slip in Part (II).
Trends observed in the experimental data of increasing deviation of pressure wave velocity from the nonslip homogeneous model, reported in Part (I), are explained from consideration of slip between ...the phases. The slip reduces the inertial effect of liquid and consequently brings about an increase in the wave propagation velocity.
In order to testify quantitatively to the above interpretation by analysis of observed data, the theoretical approaches of perturbation method and Fourier transformation in time and space were applied to the fundamental equations of mass and momentum of each phase, taking the interaction between the phases as a function of the relative velocity only. The propagation velocities dependent on frequency were calculated from the characteristic equation derived by the above procedure, and fairly good agreement was obtained between theoretical and experimental data arranged with frequency as parameter.
Applicability of linearization theory and relaxation of shock formation are physically discussed, and they are attributed also to attenuation effect by slip.
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