Linear beam raster for cryogenic targets

Based on the H-bridge switch technique a linear beam raster system was developed in 2002. The system generates a rectangular raster pattern with highly uniform (∼95%) raster density distribution on cryogenic targets. The two raster frequencies are 24.96 and 25.08 kHz. The turning time at the vertex is 200 ns and the scan linearity is 98%. The beam-heating effect on the target is effectively eliminated. The new raster system allows the use of higher beam current toward 200μA in many of the experimental proposals at end station Hall A and Hall C of the Jefferson lab.