Vibration properties of hard x-ray telescope on board satellite

ASTRO-H is the new Japanese X-ray astronomy satellite for launch in 2013. HXT on board the satellite has a mirror housing which is a cylindrical case and contains reflection mirror foils, which are constrained by alignment bars. In order to investigate vibration properties of HXT on board the satellite, vibration tests and FEM analyses were conducted. From the results of x-vibration test, it was found that there were no resonant frequencies at frequency less than 120 Hz. It also appeared that foils move along grooves of alignment bars when the housing was vibrated because kinetic connection between foils and alignment bars is only friction force. From the simulated results, this loose connection used in the actual HXT housing is useful to suppress a strong resonance at 51Hz predicted by supposing tight connections such as adhesiveness. As for z-vibration properties, vibration property of the housing was complicated since foils leap when zacceleration becomes larger than 1G. However it could be confirmed that the distinct resonant peaks did not appear at frequency less than 200 Hz. From these results, it was found that HXT housing had not any resonant frequencies less than 120 Hz, which is the maximum frequency of sinusoidal vibrations applied when launched.