Enhanced ion acceleration by focusing an intense electron beam inside a dielectric collimator

Abstract

Enhancements in the acceleration of positive ions were observed by converging an intense electron beam (250 keV, 6 kA, 80 ns, cm from the Kilo Ampere Linear Injector (KALI-200)), into a short dielectric collimator having a radius of about the beam radius and a length around the potential-well characteristic length . These were in comparison to the results of a beam injected from a planar diode into an collimator where the ion current, , recorded was only to 5 A of 150-250 ns pulse width which included - particles of , , of peak energy of , 10.8 and 14.4 MeV respectively. The ion energy increased with the electron beam propagation distance and resulted in the elongation of the ion pulse in total agreement with the theory. The magnitude of the ion current followed the trend of the propagated electron current which decreased with distance. When the electron beam was focused by a convex anode having , the ion current increased to 9-16 A and to MeV as a result of the field enhanced potential well. was further enhanced to 20-30 A and the energy to 1.5 MeV by increasing the collimator thickness to 4-8 mm. Peak energies of , and generated were of the order of 18, 24 and 28.5 MeV. In terms of the energy invested, these results are an improvement over other work.