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%.

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Convection and diffusion in the discharge region of a metal halide lamp is studied using a computer model built with the plasma modelling package Plasimo. A model lamp containing mercury and sodium iodide is studied. The effects of the total lamp pressure on the degree of segregation of the light emitting species are examined and compared to a simpler model with a fixed temperature profile. Significant differences are observed, justifying the use of the more complete approach.

By using a 3 electron-group model to describe the deviation from a Maxwellian electron energy distribution, a collisional radiative model describing a low temperature Ar-Hg plasma is greatly improved. Previously, the ionisation mechanisms of such plasmas, commonly used in fluorescent lamps, could not be satisfactory modelled. Where using a Maxwellian electron energy distribution showed the production of argon ions to be dominating over the production of mercury ions, the 3 temperature approximation yields a mercury ionization rate which is 30 times larger than the argon ionization rate.

When a plasma is sustained in the open air, nitrogen will diffuse into the plasma. Especially for plasmas sustained by the 'Torche à Injection Axiale' (TIA) this appears to be the case, since this turbulent jet draws gases from the surroundings. In the argon plasma the entrained nitrogen is probably converted into N + 2 (via charge transfer with argon ions), which is consequently destroyed by dissociative recombination (DR). This mechanism affects the plasma in two ways: (1) it offers an important loss channel for the free electrons and (2) the gas is heated by the kinetic energy of the nitrogen atoms produced in the DR reaction.

. (1998). The influence of molecular gases and analytes on excitation mechanisms in atmospheric microwave sustained argon plasmas. Fresenius' Journal of Analytical Chemistry, 362(5), 440-446. DOI: 10.1007/s002160051104General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract The effect of introducing molecular compounds into argon plasmas has been studied using an expanding microwave induced plasma at atmospheric pressure. Besides the use of optical emission spectroscopy (OES), also the time dependent behavior of line intensities during power interruptions has been studied. From the measurements it is found that even an injection of small amounts of molecular compounds (> 0.5%) leads to important changes in excitation mechanisms in the plasma. It is also found that in the recombination zone downstream in the plasma an excitation mechanism which is independent of the electron density, e.g. excitation transfer from metastables or Penning ionization, must be responsible for the excitation of analytes.

In order to improve the realism of our Plasimo computer model [1,2] in modelling multi-ion mixtures, we developed and implemented a self-consistent multicomponent diffusion model based on frictions. As presented, this diffusion model includes effects of the ambipolar electric field as well as any external electric fields. Moreover, it is comparatively easy to include other diffusion contributions. This model was shown to produce good and consistent results for both single and multi-ion mixtures.

A simple three electron temperature model was applied to a one-dimensional, fully self-consistent model of a positive column discharge, as typically found in fluorescent lamps. It was shown that this model yields results that are in good agreement with reality, regarding important parameters such as the electrical conductivity, the electron temperature and the amount of radiation produced, and that it constitutes a significant improvement over a calculation based on a Maxwellian electron energy distribution function.