Design and Experimental Validation of High-Resolution Single-Shot Emittance Diagnostics for Heavy-Ion Beams

A pepper-pot diagnostic device was developed to accurately and robustly retrieve particle distribution in horizontal and vertical phase spaces by single-shot emittance measurements. Two masks that differ in both composition and manufacturing method were fabricated: one made of phosphor bronze by an optical lithography process and another made of stainless steel (SUS) by laser cutting. Scanning electron microscope (SEM) measurements of the two masks revealed that the former is superior in terms of regularity and shape of the mask holes and is therefore more suitable to use. A new image-processing algorithm, namely, cluster noise removal method, was developed which improves the resolution of the phase-space distribution measurements over traditional methods. The device was tested in experiments with low-energy argon beams generated by an electron-cyclotron resonance (ECR) ion source at Korea Institute of Fusion Energy (KFE), Daejeon, South Korea. The results show that the diagnostics can robustly and reliably retrieve the four-dimensional (4-D) phase-space distribution of ion beams with a single-shot measurement.