A. Kashyap | Searcharxiv

arXiv2018

Estimating Stellar Atmospheric Parameters by Automated Methods Using SSLs

Libraries of stellar spectra, such as ELODIE (Prugniel & Soubiran 2001), CFLIB (Valdes et al. 2004), or MILES (Sánchez-Blázquez et al. 2006), are used for a variety of applications, and especially in modelling stellar populations (e. g. Le Borgne et al. (2004)). In that context, apart from the completeness and quality of these spectral databases (Singh et al. 2006), the accurate calibration of stellar atmospheric parameters, temperature (Teff), surface gravity (log g), and metallicity ([Fe/H]), is known to be critical (Prugniel et al. 2007; Percival & Salaris 2009). We discuss the technique of determining stellar atmospheric parameters accurately by `full spectrum fitting'.

astro-ph.SR↗

arXiv2016

Measurement of Wave Electric Fields in Plasmas by Electro-Optic Probe

Electric field measurement in plasmas permits quantitative comparison between the experiment and the simulation in this study. An electro-optic (EO) sensor based on Pockels effect is demonstrated to measure wave electric fields in the laboratory magnetosphere of the RT-1 device with high frequency heating sources. This system gives the merits that electric field measurements can detect electrostatic waves separated clearly from wave magnetic fields, and that the sensor head is separated electrically from strong stray fields in circumference. The electromagnetic waves are excited at the double loop antenna for ion heating in electron cyclotron heated plasmas. In the air, the measured wave electric fields are in good absolute agreement with those predicted by the TASK/WF2 code. In inhomogeneous plasmas, the wave electric fields in the peripheral region are enhanced compared with the simulated electric fields. The potential oscillation of the antenna is one of the possible reason to explain the experimental results qualitatively.

physics.plasm-ph↗