A single-shot beam characterization device based on the pepper-pot principle

For characterizing the ampere-scale microsecond single-pulse ion beam, a pepper-pot based beam profile measurement device was developed at Peking University (PKU). It is a combination of Faraday cup technique with pepper-pot measuring facility. The total beam current is measured by a Faraday cup and there is an array of pepper-pot holes at the bottom of the Faraday cup, which takes sample beamlets from the whole beam profile for beam distribution measurement. A Faraday cup array, that locates 3 mm away from the pepper-pot mask, is used to measure beamlet currents, so that the distribution and the transverse size of the main beam can be determined. To suppressing the secondary electrons two pairs of permanent magnets are mounted at the entrance of the main Faraday cup and in front of the Faraday cup array, respectively. In this paper we present the details of the physical and mechanical design, and the future developments on pepper-pot devices are discussed, too.