Precise Control of Characterization of a Low-Pressure Plasma Jet by Applying the Magnetic Field

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Plasma jet has been frequently utilized in the metallurgical and chemical processes, such as welding, cutting, solid waste processing, plasma spraying and powder synthesis and further energy conversion systems such as MHD generator and space craft propulsion so far. In these processes and energy conversion systems, it is very important to control precisely not only the characteristics of gas temperature and velocity but also the plasma parameters such as the energies and densities of electrons and ions.Then these characteristics of plasma jet, in fact, can be controlled by the external operated parameters of the input electric power, the frequency, gas compositions and flow rate, chamber pressure and applied electromagnetic field. Among these parameters, applying magnetic field may be one of the most effective methods to control precisely both the macroscopic and microscopic characterizations of plasma jet under the clean and stable conditions. That is, successful plasma control would … More result in the high quality process control and increase of the energy conversion efficiency.The present report describes the effect of the strong mirror type magnetic field on the thermal-fluid characteristics and also plasma parameters of a low-pressure argon plasma jet in the pipe.The main results obtained here are summarized as follows1. The plasma jet extends to the farther downstream considerably with the magnetic field strength due to the magnetic compression and the Lorentz force in the radial direction. Around the core region of the jet, of which the degree of ionization is the highest, the gas temperature rises a little with the magnetic field strength due to the Joule heating.2. The electron number density increases with the magnetic field strength in the core region, in which the radial gradients of electron temperature and electron number density become steep, due to the magnetic confinement of electrons toward the core of the jet.3. The ionic excited temperature is larger than the atomic one. And it increases more rapidly in the core region with the magnetic field strength due to the active excitation. Less