Radiofrequency modulation in the Thoneman ion source

Abstract

A fast energy analyser using a scintillation detector has been made which is able to trace the spectrum in 20 μs. It is shown that the ion beam has r.f. modulation of about 50 eV. A demodulating r.f. field after the exit channel eliminates this modulation if the ions pass through it at right phase, and thus the energy spread of the beam is diminished below 10 eV. By determining the time of flight of ions from the r.f. modulation to the demodulating field the conclusion was drawn that the r.f. modulation occurs immediately near the cathode.