Collective CO2 laser scattering on moving discharge structures in the submillimeter range in a magnetohydrodynamic generator

Collective scattering of CO/sub 2/ laser light on electrons is used to determine the radial scale length of the discharge structures occurring in a closed cycle magnetohydrodynamic generator. Heterodyne detection of scattered radiation is used to obtain a spatial resolution in the submillimeter range and to increase the signal to noise ratio. A discharge model is formulated to interpret the measured signals. The scale length of the electron density fluctuations is found to be (2.5+or-0.5)*10/sup -4/

Collective CO2 laser scattering on moving discharge structures in the submillimeter range in a magnetohydrodynamic generator

Collective scattering of CO/sub 2/ laser light on electrons is used to determine the radial scale length of the discharge structures occurring in a closed cycle magnetohydrodynamic generator. Heterodyne detection of scattered radiation is used to obtain a spatial resolution in the submillimeter range and to increase the signal to noise ratio. A discharge model is formulated to interpret the measured signals. The scale length of the electron density fluctuations is found to be (2.5+or-0.5)*10/sup -4/

Approaches for clarifying excitation mechanisms in spectrochemical excitation sources

It is shown that the state of an ICP plasma can be adequately described by a measured electron density distribution. Even though the plasma is not in full local thermal equilibrium (LTE), the electron temperature can be deduced from the density with the LTE relation with more accuracy than direct measurements permit. From energy and mass balances considerations it is argued that the deviations from LTE are sufficiently small; the ground state of the argon atom is underpopulated with respect to LTE. Spatially resolved measurements of excited state densities of argon neutrals and analyte neutrals and -ions are in good agreement with this " close enough to LTE "-concept. Only the levels of excited analyte ions which are resonant with the argon ion ground level show a significant overpopulation with respect to LTE. This is shown to be caused by the charge transfer process

On the charge transfer in an inductively coupled argon plasma

Absolute population densities for several excited states of magnesium are obtained for several locations in an inductively coupled plasma (ICP). They were used to construct Boltzmann-Saha plots for these positions and show that magnesium is close-to-LTE. The deviations from LTE are mainly limited to the levels sensitive to charge exchange with argon ions. These measured deviations can be explained by a simple model which shows that, although charge transfer is a dominant excitation and ionization mechanism in an ICP, the associated LTE deviations are limited in magnitude

On the charge transfer in an inductively coupled argon plasma

Absolute population densities for several excited states of magnesium are obtained for several locations in an inductively coupled plasma (ICP). They were used to construct Boltzmann-Saha plots for these positions and show that magnesium is close-to-LTE. The deviations from LTE are mainly limited to the levels sensitive to charge exchange with argon ions. These measured deviations can be explained by a simple model which shows that, although charge transfer is a dominant excitation and ionization mechanism in an ICP, the associated LTE deviations are limited in magnitude