EXPERIMENTAL-VERIFICATION OF THEORETICAL-MODELS SIMULATING THE TEMPERATURE INCREASE IN EPMA OF GLASS

The temperature field in glass exposed to electron beams of different diameters and deposited energy was calculated. A cylindrical shape of the excited volume was chosen for the heat source, having a diameter e qual to the diameter of the beam and a height equal to the maximum ran ge of electrons calculated with the Kanaya and Okayama formula. The gr id method for the numerical calculation of the partial differential eq uation for the heat transport was used. The calculated temperature fie ld was verified by means of specially prepared glass-ceramic samples t hat crystallize over a suitable temperature range. Scanning electron i mages of the cross-sections of the exposed areas have given satisfacto ry results, in good agreement with calculated temperatures. It has bee n found that at normal conditions of EPMA when the absorbed current do es not exceed 10 nA the maximum temperature in glass remains far under the transformation interval of the glass and cannot be the main reaso n for the rapid escape of alkali ions from the excited volume.