STUDY OF FUNCTIONAL ENHANCEMENT OF THERMAL PLASMA JET

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To enhance the functions of thermal plasma flow using strong magnetic field, an experimental study of Argon plasma jet was carried out to examine the influence of the strong magnetic field on the flow behavior. The axial magnetic field was applied to the jet in a vacuum chamber by means of a pair of superconducting coils. Measurements were conducted under a variety of conditions of the distance from the plasma torch to the temperature measurement position, the supply current to the torch and the magnetic field. It is clarified in the present study that the thermal plasma jet is significantly affected by the strong magnetic field. That is, it was indicated from the relative line intensity measurement that the excitation temperature between the coils increases with the strength of magnetic field. This result shows that the strong magnetic field makes the plasma jet compress radially and that, consequently, the jet extends to the downstream region.The behavior of the plasma jet in the vacuum chamber was also shot through the windows for observation by a digital video camera. It was indicated from the observation that the width of the jet reduces with the application of strong magnetic field and that, consequently, the high temperature region, located in the middle of the jet, is extended to downstream direction. Moreover, the high temperature region in the middle of the jet becomes much brighter with the magnetic field than that without magnetic field.In addition, the relative spectral response of the present optical system was measured by means of the device for calibration set at the measuring position in the chamber. The results show the same trend as those from a lamp of tungsten filament.