Development of Multi Faraday Cup Assembly for Ion Beam Measurements from a Low Energy Plasma Focus Device

TLDR

A multiple Faraday cup assembly with biased ion‑collector cups and nanosecond response was built to measure pulsed ion beams from a low‑energy plasma focus device, capable of detecting ion energies from a few keV to several hundred keV. The device detected ion energies down to ~5 keV—lower than prior studies—and showed that ion‑beam flux depends on filling‑gas pressure while the angular distribution is highly anisotropic with a dip at the electrode axis.

Abstract

A multiple Faraday cup assembly has been developed for measuring pulsed ion beam of a low energy plasma focus device. The Faraday cups operating in biased ion collector mode have nanosecond response and these have been used to determine the energy spectrum and flux of fast nitrogen ion beam emerging out of the pinched plasma column. The design feature that makes our Faraday cups unique is that they can register ion energy of higher kinetic value (∼hundreds of keV) as well as lower kinetic value (∼keV). It has been possible to register the ion energy upto a lower kinetic energy threshold of ∼5 keV which is a value much lower than that obtained in any previous works. The correlation of the ion beam flux with filling gas pressure is also reported. Angular distribution of ion measurement reveals a highly anisotropic emission indicating an ion dip at the electrode axis.