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 200 μ A in many of the experimental proposals at end station Hall A and Hall C of the Jefferson lab.