Production of pulsed F− beams

Process of F⁻ ion formation is examined in a surface flashover plasma initiated on the CF2 cathode of an MID by an auxiliary coaxial Marx generator. Off-diode optical measurements of FI, FII and HB show that a maximum density of the order of 10 cm for F atoms is achieved several hundred ns after the initiation of the flashover with an optimum input power of 150J. From the measured atomic densities of F and H together with the current densities of accelerated F⁻ and H⁻, 20mA/cm² and 40mA/cm² respectively, it is concluded that a significant fraction of F atoms are liberated from the CF2 surface in the form of F⁻.