Patent ID: 8425852

Claim:
A high concentration NO 2 gas generating system comprising: a circulating path configured by connecting a chamber, a plasma generator, and a circulating means; wherein said plasma generator comprises: a microwave generating apparatus; a waveguide connected to said microwave generating apparatus to transmit microwaves; and a plasma generating portion provided integrally with said waveguide and comprising a rod-shaped conducting shaft inserted through said waveguide and a tubular conducting tube, wherein said conducting shaft is configured by an antenna portion receiving said microwaves and a center electrode protruding externally from said waveguide, a ring-shaped space formed between said center electrode and said conducting tube, wherein a base end of said conducting tube is electrically conductive and fixed relative to said waveguide; a ventilation opening positioned toward said base end of said conducting tube and to an outside edge of said conducting tube; a pipe operatively connected to said conducting tube; and a shielding tube inserted into said conducting tube, wherein an outside edge of said shielding tube is connected to said pipe, wherein NO 2 is generated by circulating a gas mixture including nitrogen and oxygen in said circulating path.