Design and Simulation of 10kW Faraday Cup for Ion Beam Current Measurement

Abstract

Faraday Cups (FCs) have been used since a long time to measure the beam current in particle accelerators. The charge collected by the beam stopper is used to measure the intensity of the beam current by an ammeter. Here, at IPR (Institute for Plasma Research) the Faraday cup is used to measure the deuteron beam current in 14 MeV neutron generator. The FC presently used is for 300 KeV beam and 500μA beam current whereas the new design is proposed for deuteron beam ranging from 300–400 KeV and 20mA beam current. The energy of Ion beam is usually very high in comparison to the work function of the material resulting in the emission of the secondary electrons which can escape from the cup and effect the current measurement. Simulations for the suppressor voltage required to suppress all the secondary electrons has been carried out using SIMION8.0 and LORENTZ. Materials like Copper, Molybdenum, Tantalum etc are commonly used in manufacturing of FCs and the present paper shows the inter-comparison between the use two FC material namely Copper and Molybdenum. The heat load deposited from the beam has been analytically simulated and proper cooling system has been suggested. Simulations for selection of FC material and heat load are needed to be carried out for the new FC and its cooling system, using analysis tools like SRIM, ANSYS WORKBENCH etc. The results of these analysis are reported in this paper. The final fabrication of the FC will be based on these simulations and analysis.