Production of pulsed F− beams

Process of F
^-
ion formation is examined in a surface flashover plasma initiated on the CF
₂
cathode of an MID by an auxiliary coaxial Marx generator. Off-diode optical measurements of FI, FII and H
_β
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/cm
²
and 40mA/cm
²
respectively, it is concluded that a significant fraction of F atoms are liberated from the CF
₂
surface in the form of F
^-
.