IMPROVEMENT ON PROPERTY AND WORKING LIFE OF FREEMAN SOURCE

IMPROVEMENT ON PROPERTY AND WORKING LIFE OF FREEMAN SOURCE 1 first-author 1 1 1 1 1 Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China The magnetic mirror field caused by a pair of mild steel circular in 15 mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81%, and the heating filament current can be decreased from 130 A down to 100 A for a new filament of 2 mm in diameter. The Mo shield cylinders in 14 mm diameter put behind the reflect cathode surrounding the BN insulator prevent the metallization of BN insulators, and result in increasing the stability of arc discharge till to the end of filament working life. Because it restricts the deposition of the sputtered W and Mo atoms on the BN insulator, and maintains a high resistance of 70 MΩ between the anode and cathode. The combination of cathode shield cylinder and forming magnetic mirror field improves the running property, life of the Freeman source being about 40 h. Freeman source Nitrogen spectrum Cathode shield and magnetic mirror field REFERENCES Freeman J H . Nucl Instr and Meth , 1963 ; 22 ( 2 ): 306 Nucl Instr and Meth Hinked Holger . Nucl Instr and Meth , 1976 ; 139 : 1 Nucl Instr and Meth Aitken D . Radiation Effects , 1979 ; 44 ( 1-4 ): 159 Radiation Effects Williams N . Int Phys Conf Ser , No. 38 , Chap.2 , 1977 ; 70 Sun Guanqing , Zheng Sixiao , Duan Xiaoyu et al . J of Sichuan University (in Chinese), Natural Science Edition , 1993 ; 30 ( 4 ): 482 J of Sichuan University (in Chinese), Natural Science Edition 1994-02-25 1994-08-01 2021-02-05 1994 Nuclear Science and Techniques 3 5