JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 9, No. 8, August 2007, p. 2653 - 2656 A double monochromatization effect in low temperature plasmas G. MUSA * , C. SURDU-BOB a , R. VLADOIU Ovidius University, Mamaia 124, 900527, Constanta, Romania a National Institute of Lasers, Plasma physics and Radiation Physics, Atomistilor 409, Bucharest, Romania In a number of previously published papers we presented the monochromatization of the noble gas spectra at the addition of hydrogen or oxygen to the noble gas discharges. As plasma source we used before pulsed or even d .c. low power discharge ( 2kV ) peak to peak pulsed with the frequencies up to10 20kHz − . In the case of the present experimental researcher we report the use of increased power with the voltage pulses up to 25kV and a frequency of 25 KHz This increased performance will extend the area of gas mixtures in which the M- effect can be established. Even, in present experiment we report the ignition of multiple gas discharges with one wavelength (monochrome) emission l. (Received June 22, 2007; accepted June 27, 2007) Keywords: Monochromatization effect, Low temperature plasma 1. Introduction The Monochromatization effect (M-effect) was put in evidence over 20 years ago by a research group at the National Institute for Lasers, Plasma and Radiation Physics - Bucharest. The effect consists in the emission of a single spectral line of plasmas ignited in certain gas mixtures. Since then, the effect was continuously studied both for finding new theoretical aspects of physics and also for its great potential for applications [1]. Correlating our experimental results on the M-effect with published data on various types of gas mixture discharges, we also put in evidence the main collision process responsible for the appearance of this effect. A three body collision was found to be the elementary process that generates the monochrome radiation. For a neon-hydrogen mixture discharge, the following three- body equation was found to generate the M-effect: * * 1 ** ( 2) (2 ) ( 3) Ne H Hn Ne p H H n + − + + = ⇒ + + = (1) where Ne + is the neon ion, H - is the hydrogen negative ion, H * is the excited hydrogen atom at the level (n=2), Ne * (2p 1 ) is the excited neon atom on the neon energy level 2p 1 , H is the hydrogen atom at the ground level and finally H ** is the hydrogen atom excited to the level n=3. Dezexcitation of Ne * results in the emission of the single spectral line observed experimentally. On calculation of the energy defect of equation (1), a value of 0.1 eV is obtained. The energy defect represents the difference between the energy-states values of the colliding particles on left side and also on the right side of this equation. Thus, equation (1) is energetically resonant. The energy-state values were taken from references [6-8]. Similar results values of the energy defect were obtained for other electropositive- electronegative gas mixtures also [9]. It was thus proved that the M-effect is due to a resonant recombination of the three body reaction (1). The main feature of the M-effect is the fact that it can only be obtained in gas mixtures containing at least one electropositive gas and one electronegative gas [2]. Most experiments undertaken until now involved mixtures of a rare gas with either hydrogen or oxygen. The current paper reports on new research on the simultaneous appearance of two M-effects in a discharge tube containing two rare gases and an electronegative gas, the hydrogen. 2. Experimental arrangement The experimental setup used for the study of the simultaneous M-effect is shown schematically in Fig. 1. A quartz discharge tube of 16 mm diameter and 200 mm length provided with movable tungsten electrodes was used. The electrodes were electrically insulated using glass, apart from the 20 mm long sharpened ends. OMA Optical fiber To pumping unit R=30 KΩ + - HV 25 kV 25 kHz Quartz tubing Needle type movable tungsten electrodes Fig. 1. The experimental device. A high voltage power supply of 25 kV and 25 kHz frequency was used. A steady gas flow of different compositions was controlled by flow-meters. The spectra