Development of a pepper-pot emittance meter with beamlet intensity calibration

Emittance stands as a fundamental parameter characterizing the quality of charged particle beams. To achieve rapid and accurate emittance diagnostics for intense negative hydrogen ion beams at the end of the low-energy beam transport section, we have developed a pepper-pot emittance meter (PPEM) equipped with an absolute calibration function. By implementing optical filtering and identifying contributions from neutral particle emission, the image quality of the pepper-pot measurements was substantially improved. A specially designed calibration mask enabled the establishment of a quantitative relationship between image grayscale values and beamlet intensity over a defined number of measurement cycles. Through comparative experiments with a double-slit scanner, the reliability and applicability of the PPEM within a specific range were verified.