| 摘要 |
According to the present invention, a long electric discharge path is formed, and a workpiece is irradiated with an atmospheric plasma of a long rectangular area. An argon flow at a first gas outlet forms argon plasma by high-frequency electric power between the first and second electrodes, and the plasma is jetted as an auxiliary plasma in the longitudinal direction from the left end of a primary plasma-generating zone. Another argon flow at a second gas outlet forms argon plasma by high-frequency electric power between the third and fourth electrodes, and the plasma is jetted as an auxiliary plasma in the longitudinal direction from the right end of the primary plasma-generating zone. When high-frequency electric power is applied to the first and third electrodes, electric discharge occurs between two argon plasmas flowing from both ends of the primary plasma-generating zone. Through the electric discharge, the discharge state is maintained in the entire primary plasma-generating zone. Then, oxygen and argon are supplied through gas mixture (argon and oxygen)-supplying pipes to the plasma-generating zone, oxygen plasma is generated. The oxygen plasma is jetted through 170 second holes disposed at the bottom side wall of the cylindrical section to the outside in a direction normal to the side wall, whereby a workpiece is irradiated with oxygen plasma in a long belt-like area having a length of 50 cm.
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