Influence of the space charge of an ion beam on the time-of-flight diagnostics of its composition

Abstract

The results of time-of-flight diagnostics of the composition of high-intensity pulsed ion beams are presented. The experiments were performed on a diode of focusing and flat geometry, in the mode of self-magnetic insulation of electrons (accelerating voltage 250-300 kV, pulse duration 120 ns, ion current density 20-300 A/cm2), and a focusing diode in an external magnetic insulation mode (300 kV, 80 ns, 100-200 A/cm2). A delay in the registration of protons by 40-50 ns (on the drift path 14-16 cm) was found in the absence of a delay in the registration of heavy ions. It has been shown that this delay can be related to the deceleration of light ions during the transport from the diode to a collimated Faraday cup. This effect of spatial compression of the ion beam in the direction of the drift increases its pulse power but complicates the time-of-flight diagnostics of its composition.