UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2005 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
THE EFFECTIVE VIBRATIONAL TEMPERATURE ESTIMATION BY BAND HEAD INTENSITIES OF THE N2 2+ SYSTEM IN CYLINDRICAL HOLLOW CATHODE EFFECT PLASMA


Authors:
M.Bazavan, O. Toma, I. Iova


Affiliation:
Bucharest University, Faculty of Physics, P.O. Box MG-11, Bucharest – Magurele, RO – 077125


E-mail


Keywords:


Abstract:
In H.C.E. plasma, of a nonthermodynamical equilibrium, we have studied the electronic selective excitation ant the behaviour of the excited states populations against the electric current of the plasma [1] and of the partial pressure of the He in a He + N2 gas mixture H.C.E. plasma [2]. Here starting from the intensity of a v’v’’ band of a system written as Iv’v’’ = DNv’Wv’v’’4Re(rv’v’’)qv’v’’ , where D is an instrumental constant, Wv’v’’ is the quantum of energy involved in the transition, qv’v’’ Franck-Condon factor and Nv’ upper level of an excited molecule concentration, we obtain a graph log Sv’ (In4)v’v’’ against G’(v’) which give us the possibility to determine an effective vibrational temperature. For a N2 H.C.E. plasma, obtained in a cylindrical tube of cooper electrodes, at gas pressures 1 – 10 torr, electric current discharge 1 – 250 mA, measuring the relative intensities of second positive transitions: v’ – v’’: 4- 2, 3 – 2, 1 – 2, 0 – 2 having the lower level 2 common and 4 – 3, 2- 3, 1 – 3, 0 – 3 having in common the 3 level, we have got a plausible effective vibrational temperature, which increases with the current intensities. The similar results, in different plasma sources were reported in [3] and it is due to, probably, the excitation of the higher vibrational levels by direct electronic collisions. References: [1] M.Bazavan, O.Toma, I.Iova, Rom.Rep.Phys., vol.56, no.4, p. 637-644, 2004. [2] M.Bazavan, I.Iova, O.Toma, G.Dinescu, I.E.Rosini, Proc. ESCAMPIG, Constanta, 1-5 sept. 2004. [3] D.C.Tyte, Proc.Phys.Soc., vol.80, p. 1347.