Synchrotron white beam thermal loading on polycapillary X-ray optics

Measurements and calculations have been performed of thermal loading effects on polycapillary X-ray optics due to synchrotron bending magnet white-beam exposure. Steady-state temperature increases of up to 190°C at the input end of the optic have been measured during exposure to a beam intensity of 11 W/cm2; extended exposure at these intensities produces little or no performance degradation. Time to reach steady-state thermal equilibrium after exposure to the X-ray beam has been found to be of the order of 1 min. Theoretical modeling of thermal behavior agrees with experiment. Theoretical modeling predicts that slight misalignment of the optic will not affect the thermal load. A substantial decrease in the temperature rise is expected if the air atmosphere is replaced with helium or if air flow is maintained over the optic.