Pressure distributions in a diamond anvil cell with a rhenium gasket have been measured at various pressures up to 212±6 GPa using energy dispersive x-ray diffraction with a synchrotron source. Three sets of type IA yellow diamonds were used with bevels of 5°, 7°, and 10°. For the 7°-beveled tips, a 5-μm-diam collimated beam was used to a pressure of 206±6 GPa. In the other experiments, collimators of 10-30 μm were used. In the region of the 50-μm central flat, the pressure was essentially uniform. The effect of finite collimator size on the measurement of pressure profiles is also analyzed.
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