arXiv subjects

J. Y. Zhong

Publications and source records attributed to J. Y. Zhong.

3 recordsLinked to original sources

arXiv2014

X-ray and EUV spectroscopy of various astrophysical and laboratory plasmas -- Collisional, photoionization and charge-exchange plasmas

Several laboratory facilities were used to benchmark theoretical spectral models those extensively used by astronomical communities. However there are still many differences between astrophysical environments and laboratory miniatures that can be archived. Here we setup a spectral analysis system for astrophysical and laboratory (SASAL) plasmas to make a bridge between them, and investigate the effects from non-thermal electrons, contribution from metastable level-population on level populations and charge stage distribution for coronal-like, photoionized, and geocoronal plasmas. Test applications to laboratory measurement (i.e. EBIT plasma) and astrophysical observation (i.e. Comet, Cygnus X-3) are presented. Time evolution of charge stage and level population are also explored for collisional and photoionized plasmas.

astro-ph.SR↗

arXiv2011

R-matrix electron-impact excitation data for astrophysically abundant sulphur ions

We present results for the electron-impact excitation of highly-charged sulphur ions (S8+ - S11+) obtained using the intermediate-coupling frame transformation R-matrix approach. A detailed comparison of the target structure has been made for the four ions to assess the uncertainty on collision strengths from the target structure. Effective collision strengths (Υs) are presented at temperatures ranging from 2\times10^2(z+1)^2 K to 2\times10^6(z+1)^2 K (where z is the residual charge of ions. Detailed comparisons for the Υare made with the results of previous calculations for these ions, which will pose insight on the uncertainty in their usage by astrophysical and fusion modelling codes.

astro-ph.SR↗

arXiv2008

Soft X-ray spectroscopy of highly charged silicon ions in dense plasmas

Rich soft X-ray emission lines of highly charged silicon ions (Si VI--Si XII) were observed by irradiating an ultra-intense laser pulse with width of 200 fs and energy of $\sim$90 mJ on the solid silicon target. The high resolution spectra of highly charged silicon ions with full-width at half maximum (FWHM) of $\sim$0.3--0.4Åis analyzed in wavelength range of 40--90 Å. The wavelengths of 53 prominent lines are determined with statistical uncertainties being up to 0.005 Å. Collisional-radiative models were constructed for Si VI -- Si XII ions, which satisfactorily reproduces the experimental spectra, and helps the line identification. Calculations at different electron densities reveal that the spectra of dense plasmas are more complicate than the spectra of thin plasmas. A comparison with the Kelly database reveals a good agreement for most peak intensities, and differences for a few emission lines.

astro-ph↗