Characteristics of negative ion current by control of bias voltage to second anode in Cs-free negative ion source using TPDSheet-U

The volume production of negative hydrogen ions in the produced magnetized sheet plasma is proposed to be developed as a Cs-free negative-ion source using TPDsheet-U. The extracted current density characteristics with respect to changes in the bias applied voltage to the second anode are clarified. When negative ions were extracted at 10 kV by applying a bias voltage of 0 V to + 8 V to the second anode, the extracted negative ion current value increased 1.15 times from 3.27 mA/$cm^{2}$ to 3.75 mA/$cm^{2}$ at a discharge current of 80 A and a gas pressure of 0.3 Pa. On the other hand, the current ratio $J_{EG}(e)/J_{c}(H^{-})$ of the co-extracted electron and negative ion current values could be maintained at about 0.18 to 0.47 by using a soft magnetic material filter (SMF).