Infrared imaging diagnostics for parameters of powerful ion beams formed by a diode in a double-pulse mode

Infrared imaging diagnostics on the parameters of pulsed ion beams of gigawatt power is an effective method for rapid control. It allows for the measuring of energy density distribution at the target, optimization of an ion diode operation and control of the mode of target irradiation. Spatial resolution is of 0.9-1 mm, the sensitivity of a standard thermal camera provides registration of a thermal imprint per pulse at energy densities above 0.05 J/cm². The study was performed at the TEMP-4M accelerator with the following parameters: the first pulse is negative (80 ns, 100-150 kV), followed by positive pulse (80 ns, 250-300 kV) with an adjustable pause (300-600 ns) between pulses. The ion energy density is 0.3-3 J/cm² (for different designs of the diodes), the ion energy is 250-300 keV, and the beam is comprised of carbon ions (70%) and protons. For generation of the intense ion beams a diode with magnetic self-insulation is used. For a correct application of thermal imaging diagnostics for a diode operated in a double pulse mode it is necessary to evaluate the contribution of the accelerated electrons (in the first pulse) which can heat the target. This paper presents the results of homogeneity over the cross section of an ion beam formed by a plane diode with a passive anode. The reasons for increasing the ion energy density at the bottom of the diode are discussed.