Lost electron energy distribution of electron cyclotron resonance ion sources

Abstract

To ensure further progress in the development of electron cyclotron resonance ion sources (ECRISs), deeper understanding of the underlying physics is required. The electron energy distribution (EED), which is crucial for the performance of an ECRIS, still remains obscure. The present paper focuses on the details of a well-developed technique of measuring the EED of electrons escaping axially from the magnetically confined plasma of an ECRIS. The method allows for better than 500 eV energy resolution over a range of electron energies from 4 keV to over 1 MeV. We present detailed explanation of the experimental procedure and the following data processing peculiarities with examples and discuss possible reasons of energetic electron losses from the magnetic trap, in particular the role of RF pitch angle scattering. Finally, an experimental method of approximating the confined EED based on the measurement of escaping electrons is described.

Method for estimating charge breeder ECR ion source plasma parameters with short pulse 1+ injection of metal ions

“…Ref. [3]) owing to the efficient energy transfer from the microwave electric field to the electrons on a closed magnetic isosurface where the relativistic resonance condition ω RF = ω ce = eB/γm e is met. The resulting electron energies range from a few eV to several hundred keV with the high energy electrons being strongly confined magnetically.…”