Speaker
Description
For injection into a tandem accelerator of the BNCT device at Budker INP, Novosibirsk, a steady-state charge-exchange negative ion source with a current of ~ 10 mA is being developed. The primary beam of hydrogen ions with a current of 1–2 A and an energy of 30 keV is formed by a an RF ion source using a multi-aperture four-electrode ion-optical system with ballistic focusing. The RF plasma source operated at low hydrogen supply produces a plasma with a high content of molecular ions H2+. The formed beam of hydrogen ions passes through a charge-exchange target. Fast molecular ions H2+ in the charge-exchange target dissociate into two half-energy protons and are partially converted into negative ions. The resulting negative beam with half energy is deflected by 90 degrees by a focusing bending magnet and then accelerated by a single-aperture ion-optical system to an energy of 100 keV. Residual fast atoms and protons formed in the charge-exchange target are dumped. To reduce the stripping of the negative ion beam, high vacuum is to be provided in the transport region using differential pumping by turbopumps. In the paper, we discuss a design of the primary molecular ion source and that of beam line. At present, the source design has been completed and its parts are being manufactured. Power supply and control systems of the ion source are already prepared.
