Presence Of Dense Plasma Research Articles

Satellite lines of helium-like ions in strongly coupled plasma environment

We report the transition energies and probabilities of satellite lines due to 2p2(3P0,1,2)→1s2p(3P0,1,2) transitions of He-like C,Ne,Al and Ar ions embedded in strongly coupled plasma (SCP) environment. The SCP environment is represented by the ion-sphere (IS) model and the IS radius is varied in such a way that plasma electron densities (∼1020−1026 per cm3) cover a wide range of experimental interest. Both relativistic and non-relativistic energies of 2p2(3P) and 1s2p(3P) states are reported. The relativistic MCDF results are obtained by modified GRASP2K code and the non-relativistic variational results are done by using explicitly correlated Hylleraas basis. The relativistic results are in good agreement with experimental data available in literature. The positions of intercombination lines in presence of dense plasma can be calculated from present results which are comparable with experimental measurements. The partial pressures experienced by the plasma-embedded ions are analyzed in the purview of available experimental observations. An empirical relation is reported to estimate partial pressure on ions in dense plasma environment.

MAGNETOHYDROSTATIC MODEL OF A BALD-PATCH FLARE

On 18 May, 1994, a subflare was observed in AR 7722 in X-rays by Yohkoh/SXT and in Hα at National Astronomical Observatory of Japan. The associated brightenings are due to small-scale magnetic energy release, triggered by parasitic fluxes emerging and moving at the edge of leading sunspots. Using the magnetohydrostatic equations derived by Low (1992), we model the magnetic field configuration by extrapolation of the Kitt Peak photospheric field, taking into account the effects of pressure and gravity. Hα flare kernels are shown to be located at computed separatrices associated with field lines which are tangent to the photosphere, namely 'bald patches’ (BPs). This is evidence that BPs can be involved in flares, and that current sheets can be dissipated in low levels of the solar atmosphere. The presence of dense plasma which is supported against gravity in the magnetic dips above BPs is correlated to dark elongated features observed in Hα. Mass flows in these flat fibrils are discussed in the context of energy release in the BP separatrices. The effect of the plasma on the computed magnetic configuration is shown to be of secondary importance with respect to the topology of the field.