Embodiments of systems, devices, and methods relate to selecting a raster profile for scanning a proton beam across a target. A raster profile is selected from among the plurality of plurality of possible raster profiles based on a value of a figure of merit. A beam is directed across the target surface to form a pattern that is repeated one or more times at different radial orientations to form a scanning profile. A target temperature is monitored while scanning the beam across the target surface according to the scanning profile. The scanning parameters are changeable to avoid target damaging, to improve thermal performance and to optimize particle loading.