title: Effect of plasma grid bias on extracted currents in the RF driven surface-plasma negative ion source.
abstract: Extraction of negative ions from the large inductively driven surface-plasma negative ion source was studied. The dependencies of the extracted currents vs plasma grid (PG) bias potential were measured for two modifications of radio-frequency driver with and without Faraday screen, for different hydrogen feeds and for different levels of cesium conditioning. The maximal PG current was independent of driver modification and it was lower in the case of inhibited cesium. The maximal extracted negative ion current depends on the potential difference between the near-PG plasma and the PG bias potentials, while the absolute value of plasma potential in the driver and in the PG area is less important for the negative ion production. The last conclusion confirms the main mechanism of negative ion production through the surface conversion of fast atoms.
authors.affiliation: Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
authors.forename: Yu
authors.initials: Y
authors.lastname: Belchenko
authors.affiliation: Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Ivanov
authors.affiliation: Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Sanin
authors.affiliation: Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
authors.forename: O
authors.initials: O
authors.lastname: Sotnikov
authors.affiliation: Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
authors.forename: I
authors.initials: I
authors.lastname: Shikhovtsev