State Of Hydrogen Plasma Research Articles

Colorimetry of two large flares of EV Lac according to UBVRI observations in 1996–1998

According to the data of fast UBVRI photometry of the red flaring dwarf star EV Lac obtained in the course of international cooperative observations, a fine temporal structure of two large flares (15 Oct 1996 and 10 Oct 1998) with amplitudes of 3.73 and 2.72 magnitudes in the U band have been studied. A detailed colorimetric analysis allowed us to trace variations in the flare plasma characteristics such as the optical thickness, electron density, and temperature during the development of the flare. It was revealed that, in the time period up to the maximum brightness, both flares are in the state of hydrogen plasma, which is optically thin in the Balmer continuum. In the region of the brightness maximum, both flares emit for about 1 min as an absolutely black body (ABB), the temperature of which varies from 20000 to 12000 K and 16000 to 14000 K, respectively. Then, these flares pass to the plasma state, is optically thick in the Balmer continuum. At the brightness maximum, the flares emitted as an ABB with a temperature of about 15000 and 16000 K. In the ABB approximation, the linear sizes of the flares are approximately 5 and 3% of the stellar radius at luminosity maximum. The area is 5.1 × 1018 cm2 and 1.6 × 1018 cm2.

A distribution function approach for effective occupation numbers and the equation of state of hydrogen plasmas

Une methode est presentee pour obtenir les nombres d'occupation effectifs des etats lies a partir des fonctions de distribution des paires proton-proton et electron-proton. Ceci est realise indirectement par resolution de l'equation de Poisson pour trouver le potentiel electrostatique electron-proton correspondant aux fonctions de distribution paires. En limitant les calculs aux densites faibles, il est possible de separer le potentiel electrostatique en une partie qui retient le caractere atomique et une partie due au plasma