摘要:

Theoretical line shape studies of simple emitters have provided a deep insight into the various mechanisms shaping spectral line profiles in plasmas. This paper is an attempt to describe how the line shape of simple emitters can help us predicting the profiles of more complex spectra. A model is proposed for calculating the profile of multielectron emitters in various plasmas. For the cases where ion emitter dynamics is significant, our model permits fast and accurate computations of line shapes. We discuss examples of line shapes observed in laboratory discharge plasmas and laser produced plasmas.

ISSN:0094-243X    

DOI:10.1063/1.39889

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Experimental results of Stark broadening and shift of two neutral helium lines, 3889 and 5876 A˚, in hydrogen‐helium, pure helium and argon‐helium plasmas are reported. Experimental Stark widths and shifts are compared with theoretical results obtained from three sets of semiclassical calculations of Stark‐broadening parameters using quasistatic and ion‐dynamic treatment of ions. Accounting for ion dynamics in the calculation of widths and shifts considerably improves the agreement between theory and experiments. The comparison shows a constant systematic descrepancy between the semiclassical calculations and experiment. These results suggest the feasibility of plasma‐electron‐density determination with a precision of 3–5%. A simple parametric expression that closely approximates the ion dynamic contribution to the shift of isolated lines is derived from the unified theory by Barnard, Cooper and Smith.

ISSN:0094-243X    

DOI:10.1063/1.39962

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Production and excitation of hydrogenic light ions in hot plasmas via charge exchange recombination interactions has become the method of choice for the measurements of plasma ion temperatures and rotation velocities. Several atomic physics and environmental effects can conspire to cause perturbations of the measured line profile, and hence reduced the reliability of these measurements. Unresolved atomic fine structure is sometimes nonnegligible and can cause both an artificial asymmetry and broadening of the line. At high magnetic fields, both Zeeman and motional Stark line broadening can make reliable measurements problematic. At the high thermal energies found in contemporary fusion plasmas, the cross section for charge exchange between a plasma ion and a monoenergetic beam neutral can change appreciably across the ion velocity distribution and hence across the line profile. With the proper beam‐sightline orientation, this can lead to large and measurable changes in the apparent ion temperatures and rotation velocities.

ISSN:0094-243X    

DOI:10.1063/1.39928

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Both theoretical and experimental results on spectral line broadening due to Coulomb scattering with velocity change are presented. The dependences of the Lamb dip width on the electron concentration and ionic charge have been tested for the argon‐ion‐laser lines at 501.7, 488.0, 363.8, and 351.1 nm. Doppler‐free spontaneous‐emission ionic spectra in the presence of a laser field have been observed which are more sensitive to these parameters than the Lamb dip. The Coulomb nature of the broadening has been demonstrated. Applications of the broadening measurement to ion density diagnostics and single‐frequency output optimization are proposed which were also studied experimentally. The concentrations of Ar+and Ar++have been measured in high‐current, low‐pressure discharges.

ISSN:0094-243X    

DOI:10.1063/1.39901

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A critical review and tabulation of the available experimental data on Stark widths and shifts for spectral lines non‐hydrogenic neutral atoms and positive ions has been carried out. The review covers the period from 1983 through the end of 1988 and represents a continuation of earlier critical reviews through the year 1982.

ISSN:0094-243X    

DOI:10.1063/1.39872

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Systematic experimental and theoretical study of Stark broadening of BrI and II lines from (1D2)np levels has been performed.

ISSN:0094-243X    

DOI:10.1063/1.39873

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.39874

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.39875

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It has been previously suggested1that in general the modified semiempirical formula (SEM) gives better predictions of electron‐impact width of ionized atom lines as compared to the semiempirical formula (SE). However, in the case of Si III, the predictions of SE seem to be better. The average ratio of measured and theoretical values (R) for SEM is 0.,67, while that for SE is 1.06. Studies of C III,1which has a similar electronic configuration, also show similar results (R=1.29 for SEM and R=1.21 for SE). The electron‐impact widths for Si‐III transitions2have been calculated by using the semiempirical formulation.1Resuls are given in Table 1. Experiments are under way to measure the electron‐impact width and transition probability of Si III transitions.

ISSN:0094-243X    

DOI:10.1063/1.39876

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.39877

出版商:AIP    

年代:1990

数据来源: AIP