Validity conditions for complete and partial local thermodynamicequilibrium of nonhydrogenic level systems and their application tocopper vapor arcs in vacuum |
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Authors: | Anders A. Anders S. Hantzsche E. |
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Affiliation: | Central Inst. of Electron Phys., Acad. of Sci., Berlin; |
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Abstract: | Validity conditions for complete and partial local thermodynamic equilibrium (CLTE and PLTE) of homogeneous, time-dependent, and optically thin plasmas are derived. For Cu I, electron densities of ne⩾(5×1022-5×1023 ) m-3 are required for the establishment of CLTE. For Cu I and Cu II, ne⩾(5×1021-5×1021 -5×1022) m-3 is necessary for PLTE (for electron temperatures of 1-2 eV). Application to low-current copper vapor arcs in vacuum shows that CLTE can be expected for r<200-600 μm (r=distance from the cathode spot). A further limitation follows for temperatures of 2 eV or higher if diffusion effects are taken into consideration. Consequently, the use of the LTE formulas in plasma spectroscopy of low-current vacuum arcs is very limited |
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