Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

Abstract

The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, ne, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, Te, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional–radiative (CR) model for argon. At an argon pressure of 15 mbar, the ne values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 ± 0.5) × 1019 m−3, whereas the ne value (2 ± 0.5) × 1019 m−3 obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high (∼1020 m−3). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the Te values obtained with TS are equal to 13 400 ± 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

Atmospheric microwave-induced plasmas in Ar/H2 mixtures studied with a combination of passive and active spectroscopic methods

“…[5]. The agreement with ACI measurements proves that this method is also reliable for the n e -determination.…”

“…The detection branch used for the OES is described in detail in [5]. The emitted plasma light is focused into an optical fiber, by which the light is guided to the entrance slit of a spectrometer.…”

Radio Frequency Coplanar ZnO Schottky Nanodiodes Processed from Solution on Plastic Substrates

“…To this end, vertical diodes are routinely fabricated with relatively large active area in the range of 0.001-1 cm 2 , which leads to large C j values. In contrast, in the coplanar diodes shown in Figure 1 b, the active area is defi ned by the thickness of the asymmetric electrodes employed times the nanogap length ( W ), although the extrinsic capacitance due to the 3D coupling of the electrodes through the substrate/air, must also be considered [ 15 ] (see Figure S1, Supporting Information). However, even when taking this parasitic contribution into account, and even for devices with extremely large W / d ratio (>10 000), this geometrical alteration translates to a dramatic drop in C j , potentially enabling sub-pF device capacitances and a corresponding increase in f CO .…”

Determination of the Electron Density in an Argon Plasma Jet Using Absolute Measurements of Continuum Radiation

“…The reported value of T g = 520 K leads to a gas density n a = 1.4 × 10 25 m −3 . For the determination of , we use the method described in . In short, is determined by combining the density n(1) of the argon ground state with that of the densities n(4p) of the argon 4p levels.…”