Solid-density plasma nanochannel generated by a fast single ion in condensed matter

Abstract

A plasma model of relaxation of a medium in heavy-ion tracks in condensed matter is proposed. The model is based on three assumptions: the Maxwell distribution of plasma electrons, localization of plasma inside the track nanochannel, and constant values of the plasma electron density and temperature during the x-ray irradiation. The model of multiple ionization of target atoms by a fast projectile ion is used to determine the initial conditions. An analysis of the results of the calculations performed makes it possible to define when the atomic relaxation model is a very rough approximation and the plasma relaxation model must be used. It is demonstrated that the plasma relaxation model adequately describes the x-ray spectra observed upon interaction of a fast ion with condensed target. The comparison with the experimental data justifies the reliability of the plasma relaxation model. Preassumptions of plasma relaxation model are validated by the molecular-dynamics simulation. An x-ray spectral method based on the plasma relaxation model is proposed for diagnostics of the plasma in fast ion tracks. The results obtained can be useful in examining the initial stage of defect formation in solids under irradiation with single fast heavy ions.

Role of composition, bond covalency, and short-range order in the disordering of stannate pyrochlores by swift heavy ion irradiation

“…This produces a state of warm dense matter, lasting on the order of 100 fs, during which a hot electron-hole plasma coexists with a relatively lowtemperature, ionized atomic subsystem 19,20 . The excitation of electrons to antibonding orbitals in the conduction band makes accessible phase transformation pathways precluded under equilibrium conditions, while subsequent electron-hole recombination yields phonon emission and local heating, driving the material further from equilibrium 21 .…”

Excited States of Warm Dense Matter

“…These electrons will populate an ion levels with the high excitation energies, but will not change macroscopical WDM parameters [9]. In some cases WDM it is created by high energy particles, and the problem of the excitation of the X-ray transitions does not arise at all [17,18,3]. A backlighting methods with an external x-ray sources [1,19] can be used for WDM diagnostics in all situations.…”

“…Note that the conclusion about generation of plasma inside the track of a fast heavy ion was drawn quite long time ago [23][24][25]. Nevertheless only recently [17,3] the correspondence between the plasma parameters and the observed X-ray spectra was considered for the first time.…”

“…Another example of the structured WDM is plasma formed in the track of the fast single heavy ion. Recently we have considered such plasma in [17,18,3] and have suggested so called "a plasma relaxation model" which have allowed, in particular, to describe x-ray spectra emitted by plasma in the nanochannel. The interaction of single fast heavy ion with condensed matter leads to the formation of an extensive (∼ 100 μm) excited channel with transverse size of about 1 nm as it is illustrated in Fig.2.…”

“…High intense ion beams are considered in [1]. WDM nanochannel is formed at propagation of a fast single ion through condensed matter [3]. Great amount of deposited energy in nanosecond exploding wires is suggested to explain by creation of strongly nonequilibrium solid-state-density plasma [4].…”