多荷重イオン源

概要

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A multicharge heavy ion source is examined for the 160 cm variable energy cyclotron which is being constructed at the Institute of Physical and Chemical Research. A hot cathode of an electron bombarded type is used to the ion source. A chargestate yield of ions and the source stabilities are investigated for various gases, i. e. oxygen, carbon, dioxide and nitrogen. Ion source constructions are shown in Fig. 3, 4 and 5. An anode is made of graphite at a length of 80 mm without cooling. A cathode is made of tungsten at a size of 8 mm diameter and 11 mm length, and is shielded by graphite. The source is operated an arc voltage of 300 to 500 V and an arc current of 3 to 6 A, and a gas consumption is about 0.5 to 1.0 c. c. /min.. The characteristics of the ion source operation and an ion beam extraction are shown in Fig. 10, 12, 13 and 14. The ion beam is analyzed with a 180° mass spectrometer arrangement (Fig. 8), and mass spectra are shown in Fig. 11, 15 and 16. The ratio of C3+, O3+ and N3+ to the total out put is 15%, 15% and 20% respectively, and N+4 is about 2%.