  Charge Coupled Devices (CCDs) have been successfully used in several low
energy X-ray astronomical satellite over the past two decades. Their high
energy resolution and high spatial resolution make them an perfect tool for low
energy astronomy, such as formation of galaxy clusters and environment of black
holes. The Low Energy X-ray Telescope (LE) group is developing Swept Charge
Device (SCD) for the Hard X-ray Modulation Telescope (HXMT) satellite. SCD is a
special low energy X-ray CCD, which could be read out a thousand times faster
than traditional CCDs, simultaneously keeping excellent energy resolution. A
test method for measuring the charge transfer efficiency (CTE) of a prototype
SCD has been set up. Studies of the charge transfer inefficiency (CTI) have
been performed at a temperature range of operation, with a proton-irradiated
SCD.
