Stark broadening of high principal quantum number hydrogen Balmer lines in low-density laboratory plasmas.

We present results for Stark broadening of high principal quantum number (up to n=15 ) Balmer lines, using an analytical (the "standard theory") approach and two independently developed computer simulation methods. The line shapes are calculated for several sets of plasma parameters, applicable to radio-frequency discharge (N(e) approximately 10(13) cm(-3)) and magnetic fusion (N(e) approximately 10(15) cm(-3)) experiments. Comparisons of the calculated line profiles to the experimental data show a very good agreement.

Resolving an anomaly between measured spectral linewidths of n=3 transitions in N II and O III spectra.

A reported anomaly in the experimental scaling of the widths of Stark broadened n=3, Delta n=0 spectral lines along the carbon isoelectronic sequence is not observed in the present experiments. The ratio omega(N)/omega(O) of widths for N II lines compared to those for the narrower O III lines for the same transitions is now measured as lying between two theoretical predictions, both of which show a value omega(z-1)/omega(z) greater than unity continuing throughout the sequence. In the earlier measurements, the widths (in frequency units) were actually measured as being smaller for N II than for O III, i.

Charge-exchange-induced two-electron satellite transitions from autoionizing levels in dense plasmas.

Order-of-magnitude anomalously high intensities for two-electron (dielectronic) satellite transitions, originating from the He-like 2s(2) 1S0 and Li-like 1s2s(2) (2)S(1/2) autoionizing states of silicon, have been observed in dense laser-produced plasmas at different laboratories. Spatially resolved, high-resolution spectra and plasma images show that these effects are correlated with an intense emission of the He-like 1s3p 1P-1s(2) 1S lines, as well as the K(alpha) lines. A time-dependent, collisional-radiative model, allowing for non-Maxwellian electron-energy distributions, has been developed for the determination of the relevant nonequilibrium level populations of the silicon ions, and a detailed analysis of the experimental data has been carried out.

Comment on "Highly nonlinear, sign-varying shift of hydrogen spectral lines in dense plasmas".

Possible inconsistencies between the recent hydrogen H(alpha) spectral line shift measurements and modifications of the theory of these shifts by Escarguel et al. [Phys. Rev.