Enhancement of ion beam current using anode spot in a cylindrical neutron generator

The enhancement of an ion beam current in a cylindrical neutron generator through the utilization of anode spots has been investigated. A localized high density plasma, called an anode spot, is obtained at an extraction slit with the aid of an additional positively biased electrode ( ≥ 80 V ) located behind a plasma electrode. By utilizing the anode spot, the ion current becomes several tens of times greater than non-biased plasma under the same experimental conditions. This setup provides a means to increase the ion beam current with a small input power ( ≤ 70 W ) without enlarging the slits or deterioration of differential pumping. Possible methods to optimize extraction systems and electrode structures for further ion current enhancement with anode spots are also discussed.