Characterization of the deuteron beam current in a linear accelerator for nuclear-diagnostic calibrations

Abstract

In Inertial Confinement Fusion (ICF) research, passive detection systems are often required in several applications for observing fusion-product spectra from an ICF-capsule implosion. These detection devices can be calibrated by using fusion products produced in a linear accelerator as the characteristics of the fusion products are well known. For these calibration experiments it is important to determine the absolute current of the beam striking the target, because this determines the fusion-reaction rate. A Faraday Cup was installed and used for this purpose, in which an ammeter is used to measure the charge built up on the cup that is proportional to the beam current of the accelerator. Currents up to -100p~A were measured using the Faraday Cup. For 100tA 120kV D+ current on an erbium target doped with deuterium, D-D reaction rates of -107 per second were determined. Besides the Faraday Cup, a target movement stepper motor was also successfully installed and tested, their LabView based control programs were written, and their operation procedures were documented. The secondary electron suppression capability of the cup was successfully tested as well. The Faraday Cup serves as a diagnostic for the quality of accelerator operation.