Enhanced Laser-Driven Ion Acceleration by Superponderomotive Electrons Generated from Near-Critical-Density Plasma

Ji, Bin; Yeung, M.; Gong, Zheng; Wang, H. Y.; Kreuzer, Christian; Zhou, Mingyang; Streeter, Matthew; Foster, P. S.; Cousens, S.; Dromey, B.; Meyer‐ter‐Vehn, Jürgen; Zepf, Matthew; Schreiber, Jörg

doi:10.1103/physrevlett.120.074801

Cited by 74 publications

(56 citation statements)

References 40 publications

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“…Electrons move and can gain energy in response to the electromagnetic fields of a laser pulse; the coupling of the laser pulse energy to the electrons regulates the entire relativistic intensity laser-plasma interaction. Many other secondary phenomena of interest arise from this electron heating, including ion acceleration [1][2][3][4][5][6][7][8], highharmonic generation [9], x-ray beam generation [10][11][12], and positron production [13,14]. Electron acceleration and heating in a plasma is surprisingly complex due to the collective plasma effects that affect both the laser pulse propagation and the electron motion itself.…”

Section: Introductionmentioning

confidence: 99%

“…However, a characteristic enhancement in the high-energy tail of escaping electrons is a typical observation from experiments [23] and has been attributed to other acceleration mechanisms occurring in the underdense region [19,21,24]. There is significant interest in using near-critical density plasma to enhance ion acceleration mechanisms [2,5,6,8,[25][26][27][28], or to generate bright x-ray [29] or electron-positron plasmas [30] by taking advantage of the high laser energy conversion to hot electrons and the high electron temperatures.…”

Section: Introductionmentioning

confidence: 99%

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The unexpected role of evolving longitudinal electric fields in generating energetic electrons in relativistically transparent plasmas

et al. 2018

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Superponderomotive-energy electrons are observed experimentally from the interaction of an intense laser pulse with a relativistically transparent target. For a relativistically transparent target, kinetic modeling shows that the generation of energetic electrons is dominated by energy transfer within the main, classically overdense, plasma volume. The laser pulse produces a narrowing, funnel-like channel inside the plasma volume that generates a field structure responsible for the electron heating. The field structure combines a slowly evolving azimuthal magnetic field, generated by a strong laser-driven longitudinal electron current, and, unexpectedly, a strong propagating longitudinal electric field, generated by reflections off the walls of the funnel-like channel. The magnetic field assists electron heating by the transverse electric field of the laser pulse through deflections, whereas the longitudinal electric field directly accelerates the electrons in the forward direction. The longitudinal electric field produced by reflections is 30 times stronger than that in the incoming laser beam and the resulting direct laser acceleration contributes roughly one third of the energy transferred by the transverse electric field of the laser pulse to electrons of the super-ponderomotive tail.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The unexpected role of evolving longitudinal electric fields in generating energetic electrons in relativistically transparent plasmas

et al. 2018

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“…In some scenarios where the ion energy is a critical issue, the use of advanced ion acceleration strategies could even enable a particular application on a given laser system. Neutron conversion is emblematic of this last case, since it is crucial to reach at least the energy threshold for the nuclear reaction.Among the advanced ion acceleration schemes, the use of foils coated with a low-density, near-critical, nanostructured layer [41, 42] as a target for TNSA is emerging as a promising strategy [43][44][45][46][47][48][49][50][51]. Here, 'nearcritical' means having an electron density close to the critical one, n c =π m e c 2 /λ 2 e 2 (where m e is the electron mass, λ is the laser wavelength and e is the elementary charge).…”

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confidence: 99%

Enhanced laser-driven hadron sources with nanostructured double-layer targets

et al. 2020

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Laser-driven ion sources are approaching the requirements for several applications in materials and nuclear science. Relying on compact, table-top, femtosecond laser systems is pivotal to enable most of these applications. However, the moderate intensity of these systems (I10 19 W cm −2 ) could lead to insufficient energy and total charge of the accelerated ions. The use of solid foils coated with a nanostructured near-critical layer is emerging as a promising targeted solution to enhance the energy and the total charge of the accelerated ions. For an appropriate theoretical understanding of this acceleration scheme, a realistic description of the nanostructure is essential, also to precisely assess its role in the physical processes at play. Here, by means of 3D particle-in-cell simulations, we investigate ion acceleration in this scenario, assessing the role of different realistic nanostructure morphologies, such as fractal-like foams and nanowire forests. With respect to a simple flat foil, the presence of a nanostructure allows for up to a×3 increase of the maximum ion energy and for a significant increase of the conversion efficiency of laser energy into ion kinetic energy. Simulations show also that the details of the nanostructure morphology affect both the maximum energy of the ions and their angular distribution. Furthermore, combined 3D particle-in-cell and Monte Carlo simulations show that if accelerated ions are used for neutron generation with a beryllium converter, double-layer nanostructured targets allow to greatly enhance the neutron yield. These results suggest that nanostructured double-layer targets could be an essential component to enable applications of hadron sources driven by compact, table-top lasers. feasibility of laser-driven ion beam analysis for non-destructive materials characterization. Laser-driven ion sources have been considered to test electronic components in a harsh radiation environment [18], for thermal stress testing [19], to study ultra-fast dynamics in irradiated materials [20,21], and for materials synthesis [22,23]. Ultrashort pulsed neutron sources driven by laser-accelerated ions [24-32] have been investigated for applications such as fast neutron spectroscopy [33] and radiography [34].What make these applications particularly attractive are the requirements for the ion source. Energies of few MeVs are perfectly suitable for several ion beam analysis techniques [35] or to generate neutrons with a lithium [36] or beryllium [37] converter. Moreover, for selected applications, the inherently broad energy spectrum of a laser-driven ion source [2] is not detrimental [15,17] and could even be beneficial [18]. Maximum ion energies of ∼1 MeV have been recently demonstrated even with commercial, sub-terawatt laser systems [38]. These lasersystems are truly table-top and can operate at a high repetition rate (kiloHertz). Relying on these systems could make laser-driven ion sources portable and competitive with conventional accelerators, paving the way for their widesprea...

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“…Generation of electrons which gain over 7 times the ponderomotive energy in near-critical plasmas ( c e n n  ) has recently been reported (11)(12)(13)(14)(15)(16)(17)(18) . This process is associated with important effects, such as the enhancement of ion acceleration in the near-critical plasmas (19). Electron energy beyond the ponderomotive limit is achieved by anti-dephasing acceleration (ADA).…”

Section: Introductionmentioning

confidence: 99%

Electron Acceleration in Direct Laser-Solid Interactions Far Beyond the Ponderomotive Limit

2020

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In laser-solid interactions, electrons may be generated and subsequently accelerated to energies of the order-of-magnitude of the ponderomotive limit, with the underlying process dominated by direct laser acceleration. Breaking this limit, realized here by a radially-polarized laser pulse incident upon a wire target, can be associated with several novel effects. Three-dimensional Particle-In-Cell simulations show a relativistic intense laser pulse can extract electrons from the wire and inject them into the accelerating field. Anti-dephasing, resulting from collective plasma effects, are shown here to enhance the accelerated electron energy by two orders of magnitude compared to the ponderomotive limit. It is demonstrated

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Enhanced Laser-Driven Ion Acceleration by Superponderomotive Electrons Generated from Near-Critical-Density Plasma

Cited by 74 publications

References 40 publications

The unexpected role of evolving longitudinal electric fields in generating energetic electrons in relativistically transparent plasmas

The unexpected role of evolving longitudinal electric fields in generating energetic electrons in relativistically transparent plasmas

Enhanced laser-driven hadron sources with nanostructured double-layer targets

Electron Acceleration in Direct Laser-Solid Interactions Far Beyond the Ponderomotive Limit

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