[Diagnostics of atmospheric-pressure radio-frequency capacitively coupled Ar/N2 plasma by optical emission spectroscopy].

An atmospheric-pressure Ar/N2 glow discharge was achieved in a mode stricken between bare metal plate electrodes by radio-frequency power supply at 13.56 MHz. The rotational temperature was determined by using the Boltzmann plot of the OH (A 2sigma+ --> X 2pi) radical and the variation tendency of the gas temperature versus the input power was obtained. Furthermore, the measurement of the sequences of vibrational bands of N2 second positive system (C 3 pi(u) --> B 3 pi(g)) is made and the vibrational temperature was determined correspondingly. The experiment results showed that the emission peaks of N2 (C3 pi(u)) reached the maximum at the nitrogen flow rate of 80 mL x min(-1) with increasing addition of nitrogen, the gas temperature increased from 342 to 523 K when the input power increased from 30 to 210 W, and the vibrational temperature changed slightly when the gas flow rate of nitrogen increased from 30 to 140 mL x min(-1).

[Spectroscopic investigation of the argon plasma discharge in quartz capillary at atmospheric pressure].

An arc plasma discharge with a long length of 20 cm was generated in a quartz capillary between two hollow needle electrodes in argon at atmospheric pressure with use of the sinusoidal power supply operating at 45 kHz, which was characterized by a very high electron density. The spectroscopic method of optical emission was employed to diagnose the characteristic parameters of the arc plasma discharge in the quartz capillary. The gas temperature was determined by simulating the OH A-X(0, 0) vibrational band around 300 nm and comparison with measured spectrum by means of optical emission spectroscopy. Furthermore, the electron density was measured by means of Stark broadening of the profile of Hbeta at 486.1 nm. The electron temperature was determined using a Boltzmann plot method. The experiment results show that in the argon arc plasma discharge generated in the quartz capillary at atmospheric pressure, the gas temperature of plasma is about (1 100 +/- 50)K, the electron density at the gas temperature of 1 100 K is approximately 10(14) cm(-3), and the corresponding electron temperature is (14 515 +/- 500)K. This work has accumulated some significant experimental parameters for the treatment of inner surface of large length-to-radius-ratio insulated dielectric tube using plasma, and the results are of great importance to the applications of this type of atmospheric-pressure plasma discharge.

Tunable resonant transmission of electromagnetic waves through a magnetized plasma.

We theoretically investigate the resonant transmission of circularly polarized electromagnetic waves in the electromagnetic stop band of a magnetized plasma slab using the invariant embedding method. The frequency and quality factor of the resonant mode for the right-handed (left-handed) circularly polarized wave created by inserting a dielectric layer into the plasma increase (decrease) as the magnitude of the external magnetic field increases. These phenomena are compared with the characteristics of resonant modes in metallic and dielectric Fabry-Perot resonators to show that they are due to the change of plasma reflectivity. We also discuss the damping effect due to the collisions of the constituent particles of the plasma on the resonant transmission of circularly polarized waves.