The Two-Dimensional Thermomechanical Response of Amaterials, Laminates and Structures to Pulsed Electron Beams

The thermomechanical response of five structures of varying complexity to pulsed electron beams is measured by use of a laser interferometer arrangement. The five structures are (1) a thin (uniformly irradiated) aluminum disk, (2) an aluminum disk thicker than the range of the incident electrons, (3) a two layer (kovar-silicon) laminate, (4) a three layer (glasskovar-silicon) laminate, and (5) a simple inlaid structure consisting of a kovar cup filled with glass and topped with a silicon chip. The experimental results for these structures are compared with calculations performed using the computer code TWODY3. For the first and fourth structures, the calculated and measured responses agree qualitatively, but the magnitude of the responses do not. More specifically, when the peak displacement of the initial, one dimensional, responses are compared, the experimental values are about 30 percent lower. For the first structure, the disagreement is probably the result of the inability to accurately match the energy deposition profile used in the calculation with the experimental conditions. (This condition exists only for very thin samples.) For the fourth structure, charge buildup in the glass layer ultimately leads to its failure during the experimental tests. These effects are not considered in the calculations so the disagreement is expected. For the second, third, and fifth structures, the measured and calculated responses agree very well (a few percent while experimental error is 15 percent) during the initial response and well into multidimensional response portion.