[en] The basic ideas of the model microfield method are shortly reviewed. Recent applications to the broadening of the alkali metal resonance lines, of hydrogen lines and of overlapping helium lines are presented. Some approximations are discussed with special emphasis on the problem of the ion dynamics

[en] Before looking at this problem more closely, it is worth observing that the idea of 'ion dynamics', although corresponding to the international jargon, is in fact doubly improper. 1) Not only is it a question of ion dynamics but also that of active atoms. In point of fact it is a question of the effect of the relative velocity between active atoms and disturbing ions. 2) It is not a question of the ions themselves but rather of the 'low frequency component of the plasma microfield' which is approximately the field of the ions surrounded by screen clouds formed by the electrons. In brief, it is a question of the time variation of the low frequency component of the microfield felt by the active atom in its own mark. From these observations, it will be seen that the problem of ion dynamics is linked to other phenomena. The phenomenon referred to in (1) above brings about coupling between Stark effect broadening and Doppler effect broadening. The separation of these two effects by deconvolution of the two corresponding profiles therefore constitutes an approximation. The phenomenon mentioned in (2) shows there is coupling between 'ion dynamics' and the interactions between the charged particles of the plasma. The diagram plotted during the presentation of this paper shows how an approximate decorrelation can be reached

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[en] peak broadening, which depends markedly on the reflection indices, has been observed in high resolution neutron powder patterns. It is postulated that this is due to variations in some of the unit cell parameters. From the lines which remain narrow the cell parameters (or their combinations) which behave normally can be determined. The remaining parameters have been allowed a range of values, and the resulting contribution to the peak width has been calculated. This has been combined with the normal width function of a Rietveld refinement and excellent agreement with the observed neutron patterns has been obtained. The analysis is illustrated by data from RbOD at room temperature and α-PbO. (author) 10 refs., 2 fig., 1 tab

[en] Combined effect of homogeneous broadening conditioned by random character of the molecule nucleus movement, and inhomogeneous sequential broadening on the formation of separate bands of free multiatom molecule electron-oscillative spectra is investigated. Homogeneous and inhomogeneous broadening width dependence on the temperature and number of thermal tank oscillators disturbing oscillators active in the optical transition is investigated

[en] Using a model method of loss energy simulation on the boundary surfaces, temperature and composition of an electrodynamic macroparticle accelerator arc plasma created by the evaporation of a Cu foil, have been calculated. Stark widths for Cu VI lines of interest for the arc plasma diagnostic have been calculated also, by using the modified semiempirical method

[en] In this work we study the effects of the cylindrical differential rotation upon the determination of the V sin i parameter. We show that the width of a line broadened by a cylindrical differential rotation may correspond to two different values of the V sin i parameter

[en] The Stark broadening of the line ArI 13406,6 A (3d-4f) was measured in an argon plasma with an impurity of hidrogen. The plasma was a pulsed linear discharge 25 cm long, 5 cm in diameter and operated at a charging voltage of 6 KV with a peak current of 20 KA. The profiles were measured in a shoot to shoot basis using a 75 cm monochromator provided with an InSb detector operated at liquid nitrogen temperatures. The Stark broadening of the Balmer beta line (HB) of hydrogen was used for determination of the electron densities, which ranged from 7 x 10¹⁵ to 2 x 10¹⁶ cm^-3. The Saha equations were used to obtain the electron temperatures, which ranged from 1.2 x 10⁴ to 3.0 x 10⁴ K. The results are compared with a semiclassical calculation for the width of the line

[en] A physical discussion of the validity conditions of the different approximations allows to compare the Model Microfield Method (MMM) which takes into account the collective dynamical effects resulting from simultaneous collisions and the impact approximation valid for weak or strong non overlapping collisions. Neglecting the level splitting effects, the profile of Lyman and Balmer lines is Lorentzian in the line centre and an analytical formula for the width is given. Then, fine structure and radiative lifetime effects are analysed

No abstract available