A spectroscopic method to determine the electron temperature of an argon surface wave sustained plasmas using a collision radiative model

Abstract

A method is presented to determine the electron temperature in a low pressure argon plasma using emission spectroscopic measurements and a collisional radiative (CR) model. Absolute line intensity measurements are made in order to construct the atomic state distribution function. In addition to the excited states, the ground state density is also taken into account. Because of this, the excitation temperature can be determined with high precision. A CR-model has been used to determine the degree of equilibrium departure and to obtain the relationship between the excitation temperature and the electron temperature. This method is applied to a microwave plasma which has been generated inside a quartz tube using a surfatron device. The densities of argon levels close to the continuum are used to get an estimated value of the electron density. These values are used as input data for the CR-model. For an argon pressure of 6 mbar, the 4p level densities vary between 8 × 1014 and 6 × 1015 m−3. Using the estimated values for the electron density, between 2 × 1019 and 3 × 1019 m−3, the electron temperature was found to range between 1.15 and 1.20 eV. An extensive error analysis showed that the relative error in the electron temperature is less than 6%.

Influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma

“…Because of the energy difference between the ground state and the 4 p states, this method is more accurate than comparing only excited state densities to obtain an excitation temperature in non-equilibrium plasmas. 25 A collisional radiative model is then needed to convert the estimated temperature T 13 to an electron temperature, which is beyond the scope of this study. Variations in T 13 only are presented and give a measure of the evolution of the whole Ar 4 p population.…”

Sub-60 °C atmospheric helium–water plasma jets: modes, electron heating and downstream reaction chemistry

“…Here the ASDF is constructed with the absolute density of the ground state and four excited helium state (i.e. 447.2, 587.6, 667.8, 706.5nm), and the elementary occupation of level k is given by [66] ( 5) where I kj is the transition integrated absolute intensity of relevant optical emission, A kj is the spontaneous transition probability, and E jk = E k -E j is the difference between the lower and higher atomic energy levels. D is the plasma depth in the line of sight (i.e.…”

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

“…On the other hand, the method of absolute line intensity (ALI) measurements allows the construction of the atomic state distribution function (ASDF), including the ground state. From the ASDF the electron temperature can be determined, if n e is known, making use of a collisional radiative model (CRM) [23]. As a side product, the ASDF also provides the values of the excitation temperatures of the upper part, T spec , and the bottom of the distribution, T 13 .…”

“…The electron temperature is found by means of the Absolute Line Intensity (ALI) measurements. The methods of ACI and ALI were introduced in [22,23]. In [24] they were applied to the TIA.…”