RESUMO
The string mode of operation for an electron beam ion source uses axially oscillating electrons in order to reduce power consumption, also simplifying the construction by omitting the collector with cooling requirements and has been called electron string ion source (ESIS). We have started a project (supported by INTAS and GSI) to use Schottky field emitting cathode tips for generating the electron string. The emission from these specially conditioned tips is higher by orders of magnitude than the focused Brillouin current density at magnetic fields of some Tesla and electron energies of some keV. This may avoid the observed instabilities in the transition from axially oscillating electrons to the string state of the electron plasma, opening a much wider field of possible operating parameters for an ESIS. Besides the presentation of the basic features, we emphasize in this paper a method to avoid damaging of the field emission tip by backstreaming ions.
RESUMO
An electron-optical system (with a thermal field electron source-cathode) is introduced. The system is designed to form on the target surface submicron microprobes of a power density exceeding the ablation threshold ( approximately 10(8)W/cm(2)) of condensed media. The numerical modeling of electron paths carried out using a software package (TAU) developed by the authors has shown that the proposed electron-optical system is capable of forming microprobes of a power density comparable with that of modern high-power pulsed laser sources (up to approximately 10(11)W/cm(2)).