Boron vacuum-arc ion source with LaB cathode.

We describe a pulsed vacuum arc ion source with a lanthanum hexaboride (LaB) cathode for high-dose selective implantation of B and B isotope ions. The design and main parameters of the source and its plasma generator are described, and research data are reported on the formation, transport, and magnetic separation of B and B ions extracted from the erosion plasma of a vacuum arc discharge. Cathode spots are initiated by flashover across an alumina ceramic block of diameter ∼2.5 mm located at the center of the working cathode. The design of the trigger system provides rather uniform cathode erosion, and the cathode dimensions (diameter of 14 mm, length of ∼15 mm) ensure long-term operation of the source. The plasma generator operates at a pulse repetition rate of up to 10 Hz with a discharge current pulse width of 280 µs. At an arc current of 130 A, the source provides an ion beam of a rectangular cross section of 0.6 × 6 cm with an energy of 25 keV and amplitude up to 75 mA. A mass analyzer magnet was used for mass-to-charge separation.