Effects Of Intrinsic Magnetic Field Research Articles

ATMOSPHERE EXPANSION AND MASS LOSS OF CLOSE-ORBIT GIANT EXOPLANETS HEATED BY STELLAR XUV. I. MODELING OF HYDRODYNAMIC ESCAPE OF UPPER ATMOSPHERIC MATERIAL

In the present series of papers we propose a consistent description of the mass loss process. To study the effects of intrinsic magnetic field of a close-orbit giant exoplanet (so-called Hot Jupiter) on the atmospheric material escape and formation of planetary inner magnetosphere in a comprehensive way, we start with a hydrodynamic model of an upper atmosphere expansion presented in this paper. While considering a simple hydrogen atmosphere model, we focus on selfconsistent inclusion of the effects of radiative heating and ionization of the atmospheric gas with its consequent expansion in the outer space. Primary attention is paid to investigation of the role of specific conditions at the inner and outer boundaries of the simulation domain, under which different regimes of material escape (free- and restricted- flow) are formed. Comparative study of different processes, such as XUV heating, material ionization and recombination, H3+ cooling, adiabatic and Lyman-alpha cooling, Lyman-alpha reabsorption is performed. We confirm basic consistence of the outcomes of our modeling with the results of other hydrodynamic models of expanding planetary atmospheres. In particular, we obtain that under the typical conditions of an orbital distance 0.05 AU around a Sun-type star a Hot Jupiter plasma envelope may reach maximum temperatures up to ~9000K with a hydrodynamic escape speed ~9 km/s resulting in the mass loss rates ~(4-7)*10^10 g*s . In the range of considered stellar-planetary parameters and XUV fluxes that is close to mass loss in the energy limited case. The inclusion of planetary intrinsic magnetic fields in the model is a subject of the following up paper (Paper II).

Intrinsic magnetic field effects in organic semiconductors

Abstract

Investigating the influence of traps on organic magnetoresistance by molecular doping

Traps are localized, deep lying energetic states and are generally considered detrimental for organic semiconducting devices. In this work, we investigate their influence on the magnetic field sensitive current in organic devices, an effect often called organic magnetoresistance. Polymer thin films were doped with materials well known to influence trap characteristics in such devices. We analyzed the observed trends in the intrinsic magnetic field effects in terms of a trapped trion model, which incorporates the spin dependent formation of excitations at these trap sites. The results provide strong evidence that the intrinsic traps in the polymer material are indeed at the origin of these magnetic field effects. This shows that traps have beneficial properties and that their control may provide an appealing route for the engineering of efficient organic magnetic field sensors.

Effect of surface potential and intrinsic magnetic field on resistance of a body in a supersonic flow of rarefied partially ionized gas

The character of flow over a body, structure of the perturbed zone, and flow resistance in a supersonic flow of rarefied partially ionized gas are determined by the intrinsic magnetic field and surface potential of the body. The effects of intrinsic magnetic field and surface potential were studied in [1–4]. There have been practically no experimental studies of the effect of intrinsic magnetic field on flow of a rarefied plasma. Studies of the effect of surface potential have been limited to the case R/λd 102 (where R is the characteristic dimension of the body and X is the Debye radius). At the same time R/λd>102, the regime of flow over a large body, is of the greatest practical interest. The present study will consider the effect of potential and intrinsic magnetic field on resistance of a large (R/λd>102) axisymmetric body (disk, sphere) in a supersonic flow of rarefied partially ionized gas.