An experimental study was conducted to clarify the control characteristics of a non-equilibrium plasma boundary layer flow over a biased and water-cooled flat plate in the tube induced by applying a magnetic field. Argon gas was partially ionized by a DC arc discharge at low pressure. The flat plate was set along the direction of flow in the tube, to which the positive and negative voltage could be alternatively biased. A mirror-type magnetic field was applied to the plasma boundary layer flow over the flat plate by two solenoids. The electron temperature was increased by applying the magnetic field, but the electron number density increased for the negative bias and decreased for the positive bias. Under these conditions, enhancement of the transport properties of electrons occurred. The heavy-particle temperature was increased and the thermal boundary layer thickness over the flat plate was decreased by applying the magnetic field, which resulted in an increase in the heat flux into the plate. The visualization study showed that the relative variation of the radiative temperature nearly corresponded to the electron temperature field in the applied magnetic field. This implies that the application of a combined electromagnetic field is an effective method by which to control the flow of a non-equilibrium plasma boundary layer over a flat plate.
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