Complementary optical diagnostics for determination of rate coefficients and electron temperatures in noble gas discharges
| Autor: | David J Smith, Robbie Stewart, Colin J Whitehead |
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| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Plasma Sources Science and Technology. 11:115-126 |
| ISSN: | 1361-6595 0963-0252 |
| DOI: | 10.1088/0963-0252/11/1/314 |
| Popis: | We utilize an array of related optical diagnostics to deliver quantitative description of each process involving the 15 lowest levels in neon, for reduced electric fields ranging from 3×10-16 to 2×10-16 V cm2 (3-20 Td). Description of the kinetics between the 1s and 2p excited states (Paschen notation) has been obtained using CW laser collisionally induced fluorescence (i.e. fluorescence from a non-excited upper level). We have employed this technique in combination with the traditional optical emission and absorption spectroscopic studies to determine the rate coefficients describing electron-collisional excitation from the ground to the 1s and 2p states. These values, along with previously determined 1s-2p rate coefficients, have been used with current literature cross sections to provide information on the electron distribution function for energy bands of 2-8, 16.9-23.0 and 19.0-25.5 eV. Values of the electron temperatures obtained from our 1s coefficients were used for an extensive study of the ground state to 1s excitation functions. From 3 to 20 Td, the average values of the temperature corresponding to the 1s excitations ranged from 1.8 to 3.1 eV, while those from 2p excitation were in the range 1.6-2.9 eV. Our investigation of the bulk temperature using data for 1s-2p excitation suggests a scaling of ~0.5 for the published theoretical excitation function, which is supported by the new experimental cross sections of Boffard et al. A quantitative description of cascade to the 1s states is also presented, showing that at the top of our reduced field range, cascade from the 2p states contributes 29-35% of the total excitation rates from the ground state. |
| Databáze: | OpenAIRE |
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