Ionization of atoms by dense and compact beams of extreme relativistic electrons

TL;DR

This paper explores new ionization mechanisms caused by dense, relativistic electron beams, highlighting how their coherent and field-driven effects significantly enhance atomic ionization and can be used to analyze beam properties.

Contribution

It introduces two novel ionization mechanisms—tunnel/over-barrier and coherent impact ionization—induced by dense relativistic electron beams, emphasizing their dependence on beam structure.

Findings

Identification of two new ionization mechanisms

Enhanced ionization efficiency due to coherence effects

Potential for beam property analysis using ionization signatures

Abstract

Ionization is one of the basic physical processes, occurring when charged particles penetrate atomic matter. When atoms are bombarded by very dense and compact beams of extreme relativistic electrons, two qualitatively new -- and very efficient -- ionization mechanisms arise: the tunnel or over-barrier ionization and the coherent impact ionization, which are driven by the low- and high-frequency parts, respectively, of the beam field. In these mechanisms significant fractions of the beam electrons act coherently, strongly enhancing the ionization process. They are also very sensitive to the spatiotemporal structure of the beam that can be used for analysing the beam properties.