Методом эмиссионной спектроскопии измерены функции распределения молекул по низким вращательным уровням молекулы водорода в триплетном состоянии 3 d u и определены величины вращательной и поступательной температур основного и возбужденного триплетного состояний молекулы водорода.
Method of emission spectroscopy [1—3] was used for study of rotational distributions of hydrogen molecules in ECR discharge at pressure 0.01 Torr. The experiments were performed at the facility with the dipolar plasma sources (Fig. 1) in CRPMN LPSC (Grenoble, France) [4—7]. Discharge chamber is a metal cylinder made of stainless steel with a diameter of 100 mm. Walls are insulated from the plasma by glass cylinder. Microwave power (200—1200 W at a frequency of 2.45 GHz) is divided into four parts, each of which is applied to the four dipolar plasma sources. Sources were cooled by the flowing water or liquid nitrogen vapor. Spectral studies of STP performed in two areas of the camera (3 and 4 in Fig. 1) using the spectrometer Horiba Jobin–Yvon HR1000 with spectral resolution 0.01 nm. Spectra were calibrated using the tungsten band lamp [8]. Method of relative intensities [1—3, 8, 9] was used for determination of rotational distribution function (RDF) of molecules in the state 3 d u. In visible part of spectrum the most intensive spectrum of hydrogen molecules emission was observed in the range = 601—627 nm. Spectral composition is similar to that observed in in RF discharge [10—13] and enriched by lines of singlet and triplet transitions as compares with the DC positive column [1]. Emission lines of Q-branches (Q(1), Q(2), Q(3), Q(4) и Q(5)) of sequences with v = 0—2 Fulcher - system 3 3 H2 d u, vd a g, va were choose for study the RDF of hydrogen molecules. It was shown that the RDF (J = 1—5) of hydrogen molecules in the state 3 d u coincides with the Boltzmann law and rotational temperatures 3 Trot d u for levels vd = 0—2 lies in the range 325—205 К depending on the place of determination (decreased with increasing the distance from the dipolar plasma source. Figure 2 shows the example of the RDF. Temperatures 3 Trot d u = 205—325 К are in the range of 3 Trot d u, known for gas discharge plasma in different discharges [1, 11, 12, 14—16, 20, 21]. Hierarchy of characteristic times for different hydrogen plasma processes (time of rotational relaxation R, residence time D and lifetime of excited state 3 e d u ) was determined: 3 D R e d u . This inequality shows that it is impossible correctly relate the rotational temperature 1 Trot X g and translational Tg temperature in the conditions of experiments. But it is possible to estimate the upper levels of the translational temperature in different parts of the discharge: 650 and 420 К in region 3 and 4, correspondingly. Temperature decreases with increasing the distance from the ECR plasma source. This result is indirect evidence that the above temperatures correlate with the real gas temperature.
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