Abstract. The Soft X-ray focusing Telescope (SXT), India's first X-ray telescope based on the principle of grazing incidence, was launched aboard the AstroSat and made operational on October 26, 2015. X-rays in the energy band of 0.3-8.0 keV are focussed on to a cooled charge coupled device thus providing medium resolution X-ray spectroscopy of cosmic X-ray sources of various types. It is the most sensitive X-ray instrument aboard the AstroSat. In its first year of operation, SXT has been used to observe objects ranging from active stars, compact binaries, supernova remnants, active galactic nuclei and clusters of galaxies in order to study its performance and quantify its characteriztics. Here, we present an overview of its design, mechanical hardware, electronics, data modes, observational constraints, pipeline processing and its in-orbit performance based on preliminary results from its characterization during the performance verification phase.

In this work, an attempt has been made to understand the feasibility of using a ultrahigh frequency (UHF) technique for identification of any corona discharge/ arcing in insulating material due to water droplets. The sensors of broadband type are useful for the identification of such discharges. It is realized that corona discharges/arcing initiated by liquid droplet radiates UHF signals in the entire bandwidth up to 2 GHz. The frequency content of the UHF signal generated due to corona/arcing is not much varied in epoxy nanocomposites with different weight percentage of clay content. The exfoliated/intercalated properties were analysed through TEM studies. It is realized that corona initiated discharges are of intermittent process. It is observed that the permittivity and tan(δ) reduces with increase in percentage of clay in epoxy nanocomposite material up to 3 wt%. The hydrophobicity of the material is characterized through contact angle measurement. It is realized that low weight percentage of nanoclay content in epoxy resin reduces the surface carbonization due to arcing.

No abstract

No abstract

No abstract