YU, QC (reprint author), ACAD SINICA,INST HIGH ENERGY PHYS,POB 918,BEIJING 100039,PEOPLES R CHINA.
The self-sustaining space-charge lens focuses the ion beams, which travel through the lens, by means of the electron cloud supported by the cold-cathode Penning discharge. Its focusing power mainly depends on the electron density in the electron cloud which can be determined by the rf method. In this article the structure and performance of this type of lens are reported. The relations between the focal length of the lens and external conditions are discussed.