Development, installation, and offline-beam testing of a chopping and deflecting system for the High Current Injector at IUAC

Abstract

A chopping and deflecting system (CDS) has been designed, fabricated, and tested to provide the chopped beam with various frequencies, to the experimental facilities of the Inter-University Accelerator Centre (IUAC), New Delhi. The CDS comprises four pairs of deflecting electrodes with an ascending gap from 15 mm to 21 mm to achieve the utmost effective electric field and the highest current within the same input voltage. The design, physical structure, and slit location of CDS have been verified with various simulation codes. The 90-degree beamline of a low energy ion beam facility was extended to install and test the CDS assembly to validate its electric design. The beamline was aligned using theodolite and dimensions measurement was carried out using a coordinate measuring machine (CMM). A floating type-high voltage power supply has been developed indigenously to apply the DC voltage across the four pairs of deflecting electrodes, and the amount of deflection was measured accordingly at slit location. A beam profile digitizer was used to measure the precise beam deflection within the error of ~ 0.25 mm. The measured beam deflection matches very well with the simulated value. The measured data shows that the amount of beam deflection is independent of the charge state, energy, and mass of the charged particle beam. The various ion beams of different energy, charge state, and mass were injected into the CDS system to verify the accuracy, precision, and repeatability of the measurements. The ion beam test results extend the capability of CDS to use as an electrostatic charge state analyzer. The beam test results reveal that deflection voltage directly depends on the ratio of energy to charge state (E/q). The development, installation, and offline-beam test are discussed in the article.