Practical 2.45-GHz microwave-driven Cs-free H− ion source developed at Peking University Project supported by the National Natural Science Foundation of China (Grant Nos. 11775007 and 11575013). |
(color online) The H− current under different duty factors with a fixed microwave power and pressure at extraction voltages of 35 kV and 50 kV. The background pressure is 7.0 × 10−3 Pa. |