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The energy and angular distributions of electrons have been studied by combining small angle scatterings using analytical treatment with large angle collisions using Monte Caroo calculations as a function of column density for initially power-law electron distributions and incidence angles of 0, 30, and 60°. Using these distributions the X-ray and EUV line flux as a function of column density has been computed. The flux increases with increase in column density. At the initial column densities the contribution of non-thermal electrons for the production of line flux is negligible. However, it becomes significant at intermediate column densities at which the electron energy and angular distributions have non-Maxwellian nature. X-ray and EUV flux have also been calculated as a function of electron spectral index at a fixed column density. It falls steeply with increase in spectral index. The calculated flux is compared with the observations. 相似文献
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The evolution of energy and angular distributions of electrons has been studied accounting for the reverse current effect by combining analytically treated small angle multiple scatterings with large angle Monte-Carlo calculations. Reverse current and potential variations as function of column density have been computed. It is found that the reverse current decreases steeply with increase in electron energy. However, it becomes significant for low-energy electrons. By use of these distributions and bremsstrahlung crosssection, the X-ray energy spectrum has been calculated. The nature of the resulting X-ray spectrum integrated over all column depths is similar to the one without reverse current. The time-lag between high-and low-energy photon production has been calculated. It is found that there is a small difference between time-lags as function of observation angles. This fact can be used to test the validity of the beamed thick target model. 相似文献
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Ranjna Bakaya R. R. Rausaria P. K. Koul P. N. Khosa 《Astrophysics and Space Science》1989,151(1):103-113
Evolution of electron energy distributions have been studied by combining small-angle scattering with analytical treatment of large-angle collision using the Monte-Carlo technique. By use of these, the distributions and energy loss have been calculated as functions of column density, the heating functions have been calculated at different depths of the solar atmosphere. From the heating functions, an increase in temperature produced by the electrons at different column densities has been computed. It is found that rise in temperature increases with an increase in incident electron energy. 相似文献
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The energy and angular distribution of electrons as a function of column densities initially for monoenergetic and monodirectional
electron beams and incidence angles of 0‡, 30‡ and 60‡ have been studied by combining small angle scattering using analytical
treatment with large angle collisions using Monte Carlo calculations. Using these distributions, X-ray and EUV-line flux have
been studied as a function of column density. It is observed that the line flux increases with the increase in column density,
becoming significant at intermediate column densities where the electron energies and angular distributions have a non-Maxwellian
nature. 相似文献
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We have studied the evolution of electron energy and angular distributions using Monte Carlo technique for electron beams directed vertically downwards towards chromosphere for incident energies 30 keV, and 300 keV at different incidence angles. Using these distributions we have calculated microwave flux for different frequencies at a fixed column density as well as for a fixed frequency at different column densities. We have also calculated the total microwave flux coming out of solar atmosphere and have compared it with observations. Our results agree well with observational results and produce the observed nature of flux. 相似文献
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Ranjna Bakaya Sunil Peshin R. R. Rausaria P. N. Khosa 《Journal of Astrophysics and Astronomy》1987,8(3):263-270
Evolution of energy and angular distributions of electrons has been studied by combining small-angle analytical treatment
with large-angle Monte Carlo calculations as a function of column density for initially monoenergetic and monodirectional
electrons. The incident electron energies considered are 20, 30 and 60 keV at 0°, 30° and 60° angles of incidence. Using these
distributions, time evolution of extreme ultraviolet (EUV) spectrum has been studied. The slopes of the curves calculated
compare well with the experimentally observed curve. 相似文献
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The spatial and angular distributions and also the energy spectrum of hard X-rays from solar flares have been studied in terms of the energy and angular distributions of the accelerated electron beam. The incident electron distributions as functions of column density have been computed by combining the analytical treatment of small-angle scattering with the Monte-Carlo calculations for large angle scattering. To start with monoenergetic electrons at 0°, 30°, and 60° incidence angles have been taken. Using the Bethe-Heitler total cross section and the Sauter differential cross section along with the calculated electron distributions, the bremsstrahlung flux and its angular distribution for different photon energies > 10 keV have been studied as function of column density. The shape of the calculated curves agrees with the observations of PVO/ISEE-3 lending support to the beamed thick-target model for X-ray generation with continuous injection.Physics Department, Vishwa Bharti Institution, Rainawari, Srinagar, India. 相似文献
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M. Thangarajan F. Linn Vincent Uhl T. B. Bakaya G. G. Gabaake 《Environmental Geology》1999,38(4):285-295
Groundwater modelling studies have been found to be a potential tool in planning the pre-development management of groundwater
resources in newly developing aquifer systems. One such study was attempted in Upper Thamalakane River valley, Okavango Delta,
Botswana (southern Africa). There are three major aquifers separated by two aquitards in the valley portion. The top two aquifers
are freshwater bearing zones and the bottom one is saline. The hydrological set-up of the basin is complex, as the groundwater
flow directions are opposite in the upper-unconfined and in the lower-confined aquifers. A preliminary multilayer model was
developed for this aquifer system by making use of only available data. The hydrodynamic behavior was then studied under two
prediction scenarios to evolve appropriate management decisions for locating the well field (large diameter wells) in the
upper aquifer by making use of induced river infiltration during the flood season. The aquifer response for variable river-flow
conditions was studied and the induced river infiltration was quantified.
Received: 27 August 1998 · Accepted: 8 March 1999 相似文献
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