Effects of Electron Bombardment on CdSe Crystals At T ≅ 4K

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

International Astronomical Union Colloquium ◽

10.1017/s0252921100025446 ◽

1994 ◽

Vol 144 ◽

pp. 275-277

Author(s):

M. Karlický ◽

J. C. Hénoux

Keyword(s):

Time Distribution ◽

Electron Bombardment ◽

Spatial Evolution ◽

Superthermal Electrons ◽

Flare Loop ◽

X Ray ◽

Superthermal Electron ◽

Flare Loops ◽

Chromospheric Evaporation ◽

Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

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Electron beam induced effects in Cu/GeSe2amorphous films

MRS Proceedings ◽

10.1557/proc-777-t4.7 ◽

2003 ◽

Vol 777 ◽

Author(s):

J.S. Romero ◽

A.G. Fitzgerald

Keyword(s):

Thin Films ◽

Electron Beam ◽

Simple Model ◽

Copper Concentration ◽

Negative Charge ◽

Electron Bombardment ◽

Continuous Operation ◽

Electron Radiation ◽

Crystalline Product ◽

Intense Electron

AbstractCopper migration is observed in the SEM in amorphous GeSe2/Cu thin films when an electron beam is focused in pulsed or continuous operation on the surface of these thin films. The phenomenon can be explained using a simple model in which the population of D- centers is considered to increase upon electron irradiation. The increase in the D- center population is envisaged as due to the breaking of bonds by the electron radiation and by the constant presence of negative charge in irradiated regions. Changes in copper concentration of 20%-30% have been obtained. Additionally we have observed the local crystallization of amorphous GeSe2/Cu thin films in the TEM when the samples were subjected to intense electron bombardment. The crystalline product has been identified as Berzelianite (Cu2Se).

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