Ion heating dynamics in solid buried layer targets irradiated by ultra-short intense laser pulses

Abstract

We investigate bulk ion heating in solid buried layer targets irradiated by ultra-short laser pulses of relativistic intensities using particle-in-cell simulations. Our study focuses on a CD 2 -Al-CD 2 sandwich target geometry. We find enhanced deuteron ion heating in a layer compressed by the expanding aluminium layer. A pressure gradient created at the Al-CD 2 interface pushes this layer of deuteron ions towards the outer regions of the target. During its passage through the target, deuteron ions are constantly injected into this layer. Our simulations suggest that the directed collective outward motion of the layer is converted into thermal motion inside the layer, leading to deuteron temperatures higher than those found in the rest of the target. This enhanced heating can already be observed at laser pulse durations as low as 100 femtoseconds. Thus, detailed experimental surveys at repetition rates of several ten laser shots per minute are in reach at current high-power laser systems, which would allow for probing and optimizing the heating dynamics.

Using X-ray free-electron lasers for probing of complex interaction dynamics of ultra-intense lasers with solid matter

“…This may have tremendous impact on the understanding of laser absorption at solid targets, creation of energetic electrons and electron transport in warm dense matter, including the seeding and development of surface and beam instabilities, ambipolar expansion, shock formation, and dynamics at the surfaces or at buried layers. The fast probing of such plasmas with XFELs may therefore be important for example in the field of laser fusion [11][12][13][14] or laser particle-acceleration in the radiation pressure (light-sail) acceleration regime (RPA) [15][16][17][18] as well as the target normal sheath acceleration [19][20][21][22][23] or shock acceleration [24][25][26][27], isochoric heating [28][29][30] and high harmonic generation (HHG) [31].…”

Simulations of ultrafast x–ray laser experiments

“…37,38 The generation of relativistic electrons at the front side, the transport of electrons through the target, and the subsequent formation of a sheath of electrons at the target rear side all happen on time scales below a few hundred femtoseconds. 39 They can create plasma instabilities, 40 ionize and heat the target bulk, 41 generate strong magnetic fields, or drive shocks inside the target. These phenomena can potentially be studied with high spatial resolution of a few nanometers and temporal resolutions of a few femtoseconds using x-ray lasers 42,43 We briefly outline an experiment that we plan to simulate with the tools described above.…”

Nanoscale femtosecond imaging of transient hot solid density plasmas with elemental and charge state sensitivity using resonant coherent diffraction

“…This is intimately intertwined with the ionization dynamics and the complex evolution of the bulk return currents [8,9]. These are important due to the strong magnetic and electric fields generated at these current densities, up to 10 5 T and 10 14 V/m, as well as the rapid temporal and spatial evolution of the bulk temperature, ionization state, and hence resistivity by virtue of the electron-ion collision frequency, and anomalous resistivity from strong fields [5][6][7][8][9][10]. At present, a predictive understanding of high-intensity laser-matter interactions is severely hampered by the lack of self-consistent models for the ionization and recombination dynamics, coupled with the complex electron transport and collisions, and our inability to unravel this complexity with available experimental techniques in laser-only experiments.…”