Study of Some Basic Transport Coefficients in Noble-Gas Discharge Plasmas | ||||
| Egyptian Journal of Solids | ||||
| Article 12, Volume 30, Issue 1, December 2007, Page 137-149 PDF (518.89 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejs.2007.149068 | ||||
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| Abstract | ||||
| The transport coefficients, electrical and thermal conductivities, have been calculated in argon and helium glow discharge plasmas. The electron collision frequency needs to by know [In order to calculate the transport coefficients]. The three collision mechanisms, electron-neutral, electron-ion and electron-electron collision frequencies, are all investigated. The most important internal parameters of the plasma which have a direct bearing on the calculation of the collision frequency are the electron temperature and density, and neutral atom density. The electron temperature and electron density were determined from measurements taken with a double Langmuir probe. The double probe was placed into the different regions of the glow discharge from the cathode surface to the anode. The measured electron temperature are about (0.98-6.30 eV) at discharge voltage of 400 volt for two different argon pressures 13.3 and 26.6 Pa, and (2.86-8.14 eV) for helium discharge at 750 volt and 53.2 and 79.8 Pa, respectively. The electron density, over the pressure and voltage ranges employed above, are about (1.19-7.65x109 cm -3) and (6.70- 8.18x109 cm -3) for argon and helium plasmas, respectively. In addition, the neutral atom density, nn, is computed from the gas pressure and temperature using ideal gas law. Calculated results of electrical and thermal conductivities and their ratios, Wiedemann-Franz ratios, are represented graphically as functions of electron temperature, with the gas pressure as parameter. It was found that electron energy greatly affects the plasma transport coefficients. | ||||
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