Magnetron discharge-based boron ion source Free

An ion source was designed utilizing a planar magnetron with 2-inch diameter pure boron target. The discharge can operate both in DC and pulsed modes. Boron as a semiconductor has low conductivity at normal conditions, which still is sufficient to start low-current (2 mA) high-voltage (2000 V) DC discharge. Due to the target heat insulation, it gradually rises the temperature to 300 °C and more, enabling to apply high-current pulses to the discharge gap. An improved time- of-flight methodic was used to measure the ion species in the plasma and the beam. The ion composition of plasma was examined within a wide range of DC and pulse parameters: pulse duration of 5 - 250 µs, repetition rate of 20 - 5000 p.p.s., pulse current up to 100 A. It was shown that boron ions are mostly singly ionized, and their fraction may exceed 95% at certain conditions. The rest sort of ions are singly and doubly charged argon or krypton which were used as working gases.