Wave driven N2–Ar discharge. II. Experiment and comparison with theory

Abstract

Discharges in N2–Ar mixtures are experimentally investigated by means of optical emission and absorption spectroscopy, probe diagnostic techniques, and radiophysic methods. The experimental results provide insight into the mechanisms of wave-to-plasma power transfer, N2 dissociation, creation of N2+ ions, and excitation of metastable states [N2(A 3Σu+),Ar(3P2)]. These results are analyzed in the framework of the theoretical predictions of a model developed in a companion article.

Microplasma thruster powered by X-band microwaves

“…It is noted that the effects of adding molecular H 2 and N 2 gases to monoatomic rare gas Ar plasmas have so far been studied both experimentally and numerically/theoretically (see the Appendix). [107][108][109][110][111][112][113][114][115][116][117][118][119] In the present experiments, we did not measure the T e as well as electron energy distribution function (EEDF), and so we cannot say quantitatively the effects of adding a small amount (<1%) of H 2 and N 2 to Ar on the plasma properties. However, the present optical emission spectroscopy indicated that the addition of <1% H 2 and N 2 to Ar plasmas gave rise to no significant change of the Ar I line intensities in the visible and near-ir region (and thus no significant change of the intensity ratio of the visible Ar I lines to the near-ir ones); this implies that no significant change in the EEDF and/or T e occurred with the H 2 and N 2 addition, since the upper-level excitation energies for visible Ar I lines are >1 eV higher than those of near-ir ones (as mentioned above).…”

Determination of vibrational and rotational temperatures in highly constricted nitrogen plasmas by fitting the second positive system of N2 molecules

“…Meanwhile, T rot was monotonically increased from 350 to 700 K, which is similar to Guerra et al's results of the DC discharge with high current. 17 Similarly, Henriques et al 37 also reported that the gas temperature is in the range of 500∼800 K in the constricted plasma excited by a wave driven N 2 -Ar discharge. The highly constricted plasmas exhibited a relatively low gas temperature at the high excitation power densities of 7 ∼ 85 W/cm −3 , which can be attributed the energy release at the tube wall.…”

Optical emission spectroscopy of 50 Hz pulsed dc nitrogen–hydrogen plasma in the presence of active screen cage

“…This fact may be attributed as follows: at many occasions, the electron energy distribution function does not remain Maxwellian, and the atomic/ionic densities are not in Boltzmann equilibrium; that is, excitation and de-excitation are not controlled by collisions with electrons. Under these circumstances, the local thermo-dynamical equilibrium model is not valid, and the use of the simple Boltzmann plot method only provides the excitation temperature instead of electron temperature (32,33). In this method, the spectral intensities of several spectral lines having different threshold excitation energies are employed to determine the excitation temperature of electrons.…”