Exoelectron Emission from Pyroceramic
The nonstationary electron emission (exoelectron emission) and the emission of negative charges from the surface of finely-crystalline multicomponent dielectric materials subjected to light and thermal stimulation, electron injection, and x-irradiation are examined. It is demonstrated that the exoelectron emission of dielectric materials without preliminary irradiation is associated with adsorption layers located on the sample surface. After x-irradiation and electron injection, maxima appear in the temperature dependence of the intensity of exoelectron emission caused by various defects in subsurface regions of the examined pyroceramic samples.
Abstract Many human operations have created a large population of small orbital debris in near Earth environment. The threat they represent for satellites is a major factor for the preparation of future space missions. Several experiments devoted to the study of this environment, as well as various materials exposed to space, have been retrieved in the past few years. The analysis of the results shows some differences with previous modeling. Comparison with data from LDEF and from EURECA give some insight in the long term evolution of particle size distribution. Chemical identification of particle remnants inside craters is difficult but provides valuable information on the origin of the impactors. Permanent monitoring of environment is obviously needed, especially for the type of orbits where data are presently scarce ie. heliosynchronous and geostationary orbits.