Electrolytic Tank Analogue Design and Application of Automatic Control

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It is well known that electrolytic tank analogue, which is used to measure the electric potential and the potential gradient of the electrostatic field formed analogically by the model electrodes in an electrolytic tank by a submerged probe tip, is a usual method not only for the analysis of electrostatic equipotential line distribution, but also for the solution of other fields where Laplacian equation is followed, for instance, stress analysis in the field of material, hydraulics and thermal conduction problem by analogical consideration. Furthermore, by an adequate arrangement of mechanisms, a design of electric network function, and a plotting of electron trajectory in an electrostatic field are made possible. Such wide usefulness of electrolytic tank analogue in practical purpose has resulted from the simple construction of mechanism, and the easy operation of equipment. From the viewpoint of practical use, however, many problems to be solved concerning electrolytic tank analogue still remain. This means that higher accuracy and much easier operation are necessary. In considering the accuracy of electrolytic tank analogue, the error of measurement can be said to depend principally on the following factors : the polarization of liquid near the electrodes, the perturbation of an electric field by a submerged probe, the surface tension, and the mechanical construction. Other workers reported that the factors to be concerned about the accuracy are the same as those described above, but few have made reports on the quantitative measurement of individual factors. On the other hand, in spite of the usefulness of the electrolytic tank, the manual control is tediousness as well as the waste of time to the operator. Then the application of automatic control has been desired. For this reason, it has been often tried to apply servomechanism for the electrolytic tank analogue, and some investigators have reported an automatic electrolytic tank analogue, especially, the automatic equipotential line plotter, the automatic electron trajectory plotter, and the network function designer. However, many problems concerning the mechanism and operation of these automatic equipments still remain to be solved for practical purposes. We tried an investigation for the practicalization of electrolytic tank analogue, especially the measurement of accuracy, and the automation of the equipments. First, the measurement of accuracy about the probe impedance and the polarization of liquid were tried, and then an automatic equipotential line plotter and an automatic electron trajectory tracer were constructed. This paper gives the summary of the work on the electrolytic tank analogue. In Chapter I, it is described the problems about the electrolytic tank analogue and a general explanation of the present authors' work as well as a review of previous works by others. In Chapter II, the mechanism and the general theory of electrolytic tank analogue is described. The measurement of accuracy is also given on the basis of the experiment of the authors. With respect to the polarization of liquid, the excess resistance and the capacity caused by the polarization were measured in many kinds of combinations of liquids and electrode metals. On the other hand, in reference to the perturbation by the probe, the changes in probe impedance depending on the submerged depth in every probe metals were measured from the viewpoint of minimizing the field perturbation and getting the adequate input impedance of the first stage vacuum tube amplifier of a null detector. In Chapter III, it is reported in detail the automatic equipotential line plotter which was constructed on the principle of applying the automatic control to the electroyltic tank analogue. This equipment is an extension of the usual electrolytic tank method to automatic plotting by means of servomechanism ; it causes the probe to keep itself on the equipotential line to be plotted, compensating any deviation, as it travells in one direction. The mechanism of the equipment and several examples of the equipotential line maps are given. In Chapter IV, it is described the automatic electron trajectory tracer in a electrostatic field. The method of measuring the electron trajectory in two demensional electrostatic fields is based on the fact that the radius of curvature of electron trajectory is equal to the ratio 2V/ε_n when a pair of probe wires dipped into the electrolytic tank detects V (the potential of the field formed by model electrodes where electron exists) and ε_n (the potential gradient normal to the direction of motion). The plotting is achieved by the continuous adjustment of the radius of curvature of the probe path, compensating the deviation as the probe moves on the surface of electrolyte. Mechanical design, electrical curcuit, and the performance are also discussed. In Chapter V, it is found the summary of the work about the general accuracy of electrolytic tank analogue and the attempt to apply the automatic control to it. Finally, in Appendix, it is described a new type A. C. potentiometer by which amplitude and phase difference of A. C. voltage can be measured. The characteristics of this apparatus is based on the principle that the amplitude and the phase difference of unknown A. C. voltage are measured by comparing with the standard voltage having the same frequency. In this case, the standard voltage is converted to the form a_0+jb_0 by a quadrature generator. This is a useful instrument for detecting very rapidly the resistance of electrolyte or the probe impedance. It is also a convenient tool for comparing two A. C. voltages as in the case of designing servomechanism.
東北大学の論文
1958-00-00

Electrolytic Tank Analogue Design and Application of Automatic Control

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