A Study on Plasma Diffusion in a Uniform Magnetic Field

Through gas plasmas of very low charge densities, electrons and ions diffuse freely because the space charge is negligible (free diffusion limit). On the contrary at high charge densities, the space-charge induced field saturates and causes the ambipolar diffusion which is a combination of diffusive and saturated mobility flow (ambipolar limit). The transition from the ambipolar to the free diffusion is studied for the case of magnetized slab plasmas maintained in between two plane-walls through ionization by electron collision. The basic equation is nonilnear because of the mobility flow due to the spacecharge field. A simple analytic approximation is applied to the distribution of charged particles. The amplitude of charged particle distribution and the plasma thickness are determined by an iterative numerical procedure. For typical values of the characteristic plasma parameters for magnetized hydrogen plasmas, variation of the charged particle density through the transition between both limits is investigated. Spatial distributions of electrons and ions inside the plasma slab are calculated

A Study on the Space and Energy Dependent Reactor Kinetics, with Direct Physical Interpretation of the Effective Neutron Lifetime and Criticality Factor

First, the concept of neutron importance is introduced. It is assumed that each of the neutrons produced by fission in a chain reactor possesses an importance proportional to the number of its descendants. Secondly, on the basis of the law of conservation, a transport equation of the neutron importance is derived. Then, the effective neutron lifetime is defined as the mean interval of successive fission events in the course of the importance transport. The consistent definition of the criticality factor is the neutron multiplicity during the effective neutron lifetime so defined. After defining the basic reactor kinetics parameters, such as the effective neutron lifetime and criticality factor, the persistent time behavior of nuclear chain reactors has been investigated. The kernel form reactor equation is used because of its physical intelligibility. The formulas obtained are applicable to any reactor, provided that the neutron flux and its adjoint function is known either analytically or numerically

Estimation of Annual Average Thermal Efficiency of Modern Steam Power Plants in a Large Hydro-Steam Combined Electric Power System

One of the fundamental problems in planning steam electric power generation is to estimate its annual average thermal efficiencies for a projected plant in a given electric power system. The following discussion is mainly concerned the estimation of thermal efficiency of modern type steam electric power plant to be put into the system operation

A Method for Estimating the Power Duration Curves of the Project Power in a Large Combined Hydro-Steam Power System

In planning electric power generation of a large combined hydro-steam power system, we should determine not only the power and energy but also the power duration curve, which is necessary to calculate the energies, generating hours and start-stop frequencies of each generating unit. The project power, which includes the existing steam power, will be found from the predicted load after subtracting the part assigned to the existing hydro plants. In general, the past data show that the curve, represented by the vertical distance between the duration curves of load and that of hydro power, will be greatly different from the steam power duration curve of the corresponding year. In this paper, the authors try to find out a method in which the duration curves of the predicted steam power, estimated by utilizing the past data of load and hydro power, are closely matching with the actual duration curve of steam power in the corresponding year. The diagrams, calculated by this method from the past data of a certain power system, are expected to be applicable in estimation of the duration curves of project power in near future, at least for the same power system

The Selection of the Representative Year of Stream Flow for Electric Power Generation

An analysis of the actual state of the combination of the load and the hydro-and steam-power in a large combined hydro-steam power system is necessary for any economic comparison between various types of hydro- and steam-power generation; and for the power generation by a plant of the run-off-river type as well as of the pondage and storage types, it sometimes involves an inspection of the daily stream flow in connection with the daily load curve throughout a year. In such cases, it being difficult to draw a daily stream flow diagram for the future, it sometimes becomes necessary to select the representative year representing a typical stream flow from the data in the past. This paper describes the method for its selection

On Measurement of Plasma Current Profile by Neutral Beam Probe

A neutral beam probing method is proposed for measurement of plasma current profile in a tokamak. An emulsion plate is used to detect the secondary ions. This method is compared with the ion beam probing in which the primary particles are heavy ions. It has been concluded that a neutral beam is superior to an ion beam for the purpose of determining plasma current profile. From numerical orbit calculations, it has been found that this method is applicable to the tokamak NOVA II, with moderate requirements on the neutral beam source

The Annual Average Stream Flow for Hydro-electric Power

In a large combined hydro-steam power system as in Japan, it is necessary to know what flowing condition of rivers may be expected to hold on an average for a long term, in order to plan for the economical development of hydro-power. However, the flowing condition not only varies in its total annual stream flow each year, but even seasonally within a given year, which makes it difficult for us to deal directly with the duration curves of stream flow or the daily stream flow curves which have been hitherto employed in developing hydro-power, so that we have to consider as a parameter the annual average stream flow for each year on which these depend. We need not take the average of all the data obtained in the past in order to estimate the annual average stream flow expected to hold for a long term to come, but must resort to the reasonable method of so-called time series analysis with its theoretical foundation, which takes into consideration the periodicity of the fluctuation contained in the stream flow and other factors. In this paper we propose to estimate the annual average stream flow expected to hold on an average for a considerably long term by means of an analysis, as easy and practical as possible, of a stream flow of comparatively small sample size

Plasma Diagnostics Using Two-Component Neutral Beam

A method is proposed for simultaneously determining the electron temperature and the density of a plasma by using a two-component neutral beam of argon and hydrogen. The feasibility of this method has been demonstrated on the tokamak NOVA II, using an argon and a hydrogen beam separately. The electron temperature was determined from the attenuation of an argon beam. In the central electron temperature from 100 to 250 eV, the results obtained are in good agreement with the line-averaged values of the electron temperature estimated from the temperature and density profiles which have been measured by the Thomson scattering. The ion density was determined with a hydrogen beam, and was found to be consistent with the electron density measured by microwave inter-ferometry. This method of a two-component neutral beam probing can be applied to the diagnostics of the scrape-off layer plasmas in large devices

A Theoretical Analysis of Neutral Beam Probe for Measuring Ion Temperature of a Plasma

A theoretical basis of the neutral beam probe for measuring the local ion temperature of a plasma is given. The results of numerical calculations for some typical plasmas show that it is desirable to choose the beam energy in the region of 10 keV to 30 keV for plasmas of current and of next generation tokamaks. It is pointed out that the method of least squares can be applied to determine the local ion temperature from the measured data