<正>LECR3 (Lanzhou ECR ion source No.3) is a high performance Electron Cyclotron Resonance ion source designed for atomic physics research. It was designed and fabricated in 2000, and after about one year's commissioning, it was used to deliver multiply charged ion beams for the successive atomic physics experimental terminals. This source is a double-frequency heating ion source. It was designed running at 10 GHz or 14.5