Effects of Coaxial Cylindrical Nozzle on Induction-Coupled Plasmas

A mathematical model is presented for the calculation of the two dimensional temperature fields in an induction-coupled argon plasma torch. The torch has a coaxial cylindrical nozzle for powder feeding. It is assumed that the radial velocity of gas flow is negligible and the axial velocity pattern is two step function of radius. Results were obtained for a plasma torch, 1.4 cm radius and 20 cm long. The oscillator frequency was 4 MH_z. Temperature fields based on the model were calculated for an atmospheric pressure argon plasma at magnetic flux density levels of 53 Gauss with different plasma gas flow rate over the range of 0 to 30 1/min at 0℃. As the nozzle is inserted into the torch, the plasma is cooled in the nozzle region, however, the nozzle does not greatly affect the temperature plofiles in the downstream below the nozzle region. Increasing the radius of the nozzle, firstly, the maximum power input density does not change and power input inside the torch decreases, secondly, maximum power input density is lowered and finally the torch is extinguished

LIF imaging of OH radicals in DC positive streamer coronas,” Thin Solid Films

Abstract In this study, the LIF detection of the hydroxyl (OH) radicals was performed in a nozzle-to-plane electrode system having an electrode gap of 30 mm during the steady-state positive streamer corona discharge at atmospheric pressure. For monitoring the ground-state OH radicals, OH transition [A 2 Σ + (v′ = 1) ← X 2 Π(v″ = 0)] at 282 nm was used. The time relationship between the regular streamer coronas, laser pulse, OH fluorescence and laser-induced streamer was measured. The time dependence of OH radicals between the successive streamers was measured for the evaluation of OH dynamics when the discharge was in a steady-state condition. The two-dimensional OH distribution in the DC streamer corona discharge was observed. The obtained results showed that the ground-state OH radicals were generated mainly in the filamentary part of the streamers. It was found that LIF detectable amount of ground-state OH radicals stayed in the region where streamers propagate during the steady-state DC positive streamer corona in open air

誘導プラズマに対する同軸円筒ノズルの影響

A mathematical model is presented for the calculation of the two dimensional temperature fields in an induction-coupled argon plasma torch. The torch has a coaxial cylindrical nozzle for powder feeding. It is assumed that the radial velocity of gas flow is negligible and the axial velocity pattern is two step function of radius. Results were obtained for a plasma torch, 1.4 cm radius and 20 cm long. The oscillator frequency was 4 MH_z. Temperature fields based on the model were calculated for an atmospheric pressure argon plasma at magnetic flux density levels of 53 Gauss with different plasma gas flow rate over the range of 0 to 30 1/min at 0℃. As the nozzle is inserted into the torch, the plasma is cooled in the nozzle region, however, the nozzle does not greatly affect the temperature plofiles in the downstream below the nozzle region. Increasing the radius of the nozzle, firstly, the maximum power input density does not change and power input inside the torch decreases, secondly, maximum power input density is lowered and finally the torch is extinguished