Abstract
Highly constricted plasmas are an active research area because of their ability to generate high activity of plasma beams, which exhibit potential in applications of material processing and film deposition. In this study, optical emission spectroscopy was used to study the highly constricted nitrogen plasma created at low pressure. The vibrational and rotational temperatures of molecules were determined by fitting the second positive system of nitrogen molecule. Under the conditions of the power densities as high as 7 ∼ 85 W/cm3 and the pressures of 2 ∼ 200 Pa, the determined rotational temperature was found to be relatively low, increasing from 350 to 700 K and the vibrational temperature keeping at ∼ 5000 K. The analysis of dissipated power revealed that ∼ 80 % of input power is dissipated for the nitrogen molecule dissociation and the creation/loss of ions at the tube wall, producing an as high as 1012 ∼ 1013 cm−3 plasma with the nitrogen dissociation degrees of 2%∼15%. With the increase in the discharge pressure, more input power was found to be dissipated in the dissociation of nitrogen molecules instead of creation of ions, resulting in a higher density of radicals.
Highlights
Electric discharges with highly constricted configuration have received much attention because of the potential for a series of novel applications
A cylindrical nitrogen plasma source operating at low pressure is interesting to produce high activity of plasma for synthesis of nitride films,[15,16] such as GaN, AlN, and SiNx, etc. using plasma-enhanced chemical vapor deposition (PECVD) and plasma-assisted molecular beam epitaxy (MBE)
The goodness of fits was evaluated by fitting the spectra recorded at the different spectral resolutions and the whole rovibrational bands with ∆ν = −2, −1, 0, 1, and 2, respectively
Summary
Electric discharges with highly constricted configuration have received much attention because of the potential for a series of novel applications. Microdischarges spatially confining the plasma to dimensions of 1 mm or less enable generation of stable glow discharges in a wide variety of gases at atmospheric pressure with as high as 1015 cm−3 electron density, which is considered applications as plasma cathodes.[1] Atmospheric pressure plasma jet (APPJ) is a facile tool for plasma beam production and has received much attention because of its prospect in low-temperature processing of materials.[2,3,4,5,6,7,8,9,10,11,12,13,14] it is generally difficult to prepare high-quality thin films using an APPJ system. Knowledge of the energy distributions of particles is significant to the understanding and
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