Articles de revues : « Laser-matter interaction, laser-plasma physics, laser-based ion acceleration, TNSA »

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BADZIAK, J., S. GŁOWACZ, S. JABŁOŃSKI, P. PARYS, J. WOŁOWSKI et H. HORA. « Laser-driven generation of high-current ion beams using skin-layer ponderomotive acceleration ». Laser and Particle Beams 23, n^o 4 (octobre 2005) : 401–9. http://dx.doi.org/10.1017/s0263034605050573.

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Basic properties of generation of high-current ion beams using the skin-layer ponderomotive acceleration (S-LPA) mechanism, induced by a short laser pulse interacting with a solid target are studied. Simplified scaling laws for the ion energies, the ion current densities, the ion beam intensities, and the efficiency of ions' production are derived for the cases of subrelativistic and relativistic laser-plasma interactions. The results of the time-of-flight measurements performed for both backward-accelerated ion beams from a massive target and forward-accelerated beams from a thin foil target irradiated by 1-ps laser pulse of intensity up to ∼ 1017 W/cm2 are presented. The ion current densities and the ion beam intensities at the source obtained from these measurements are compared to the ones achieved in recent short-pulse experiments using the target normal sheath acceleration (TNSA) mechanism at relativistic (>1019 W/cm2) laser intensities. The possibility of application of high-current ion beams produced by S-LPA at relativistic intensities for fast ignition of fusion target is considered. Using the derived scaling laws for the ion beam parameters, the achievement conditions for ignition of compressed DT fuel with ion beams driven by ps laser pulses of total energy ≤ 100 kJ is shown.

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Cutroneo, Mariapompea, Lorenzo Torrisi, Jiri Ullschmied et Roman Dudzak. « Multi-energy ion implantation from high-intensity laser ». Nukleonika 61, n^o 2 (1 juin 2016) : 109–13. http://dx.doi.org/10.1515/nuka-2016-0019.

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Abstract The laser-matter interaction using nominal laser intensity above 1015 W/cm2 generates in vacuum non-equilibrium plasmas accelerating ions at energies from tens keV up to hundreds MeV. From thin targets, using the TNSA regime, plasma is generated in the forward direction accelerating ions above 1 MeV per charge state and inducing high-ionization states. Generally, the ion energies follow a Boltzmann-like distribution characterized by a cutoff at high energy and by a Coulomb-shift towards high energy increasing the ion charge state. The accelerated ions are emitted with the high directivity, depending on the ion charge state and ion mass, along the normal to the target surface. The ion fluencies depend on the ablated mass by laser, indeed it is low for thin targets. Ions accelerated from plasma can be implanted on different substrates such as Si crystals, glassy-carbon and polymers at different fluences. The ion dose increment of implanted substrates is obtainable with repetitive laser shots and with repetitive plasma emissions. Ion beam analytical methods (IBA), such as Rutherford backscattering spectroscopy (RBS), elastic recoil detection analysis (ERDA) and proton-induced X-ray emission (PIXE) can be employed to analyse the implanted species in the substrates. Such analyses represent ‘off-line’ methods to extrapolate and to character the plasma ion stream emission as well as to investigate the chemical and physical modifications of the implanted surface. The multi-energy and species ion implantation from plasma, at high fluency, changes the physical and chemical properties of the implanted substrates, in fact, many parameters, such as morphology, hardness, optical and mechanical properties, wetting ability and nanostructure generation may be modified through the thermal-assisted implantation by multi-energy ions from laser-generated plasma.

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STRANGIO, C., A. CARUSO, D. NEELY, P. L. ANDREOLI, R. ANZALONE, R. CLARKE, G. CRISTOFARI et al. « Production of multi-MeV per nucleon ions in the controlled amount of matter mode (CAM) by using causally isolated targets ». Laser and Particle Beams 25, n^o 1 (28 février 2007) : 85–91. http://dx.doi.org/10.1017/s0263034607070140.

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In several experiments, faster ions were produced from the backside of solid targets irradiated by powerful laser pulses. The ion acceleration was considered due to the negative electrostatic sheath formed on the backside of the target (TNSA), or to the expansion wave starting at the backside surface, or to the expansion wave and to its embedded electrostatic rarefaction shock. In this experiment, ions have been generated by transferring energy to a controlled amount of mass before the target become transparent by gas dynamic expansion (controlled amount of mass mode (CAM)). The targets used were thin transparent disks causally isolated from the holder to trim down, during the interaction process, unwanted effects due to the surrounding parts. Two kinds of target corresponding to a different set of parameters were designed (LARGE and SMALL). Both targets were conceived to survive, in the actual contrast conditions, to the low power pulse forerunning the giant laser pulse, bigger margin but lower performances being assigned to LARGE. For comparison standard square foils under the same focusing conditions, were also studied (LARGE-LIKE and SMALL-LIKE irradiation).

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Torrisi, Lorenzo, Lucia Calcagno, Mariapompea Cutroneo, Jan Badziak, Marcin Rosinski, Agnieszka Zaras-Szydlowska et Alfio Torrisi. « Nanostructured targets for TNSA laser ion acceleration ». Nukleonika 61, n^o 2 (1 juin 2016) : 103–8. http://dx.doi.org/10.1515/nuka-2016-0018.

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AbstractNanostructured targets, based on hydrogenated polymers with embedded nanostructures, were prepared as thin micrometric foils for high-intensity laser irradiation in TNSA regime to produce high-ion acceleration. Experiments were performed at the PALS facility, in Prague, by using 1315 nm wavelength, 300 ps pulse duration and an intensity of 1016W/cm2and at the IPPLM, in Warsaw, by using 800 nm wavelength, 40 fs pulse duration, and an intensity of 1019W/cm2. Forward plasma diagnostic mainly uses SiC detectors and ion collectors in time of flight (TOF) configuration. At these intensities, ions can be accelerated at energies above 1 MeV per nucleon. In presence of Au nanoparticles, and/or under particular irradiation conditions, effects of resonant absorption can induce ion acceleration enhancement up to values of the order of 4 MeV per nucleon.

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Gopal, A., A. H. Woldegeorgis, S. Herzer, G. G. Paulus, P. Singh, W. Ziegler et T. May. « Smith–Purcell radiation in the terahertz regime using charged particle beams from laser–matter interactions ». Laser and Particle Beams 34, n^o 1 (13 janvier 2016) : 187–91. http://dx.doi.org/10.1017/s0263034615001093.

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AbstractWe report on the experimental observation of Smith–Purcell (SP) radiation generation by charged particle beam from laser–matter interactions. High-power laser pulses were focused onto a thin metal foil target to generate proton beams with energies up to 1.7 MeV via the target normal sheath acceleration (TNSA) process. The particle beam from the TNSA process was sent close to a periodic structure to generate SP radiation. Sub-μJ terahertz pulses were recorded using a pyroelectric detector. Simultaneous measurement of the ion spectra allowed us to estimate the power of the emitted radiation and compare it with the experimental results. The distance between the grating and the particle beam was varied and its effect on the emitted radiation was studied.

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Park, J., J. Kim, G. Cochran, D. Mariscal, R. A. Simpson, A. Zylstra et T. Ma. « Experimental verification of TNSA protons and deuterons in the multi-picosecond moderate intensity regime ». Physics of Plasmas 29, n^o 6 (juin 2022) : 063106. http://dx.doi.org/10.1063/5.0085300.

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Ion acceleration from high intensity short pulse laser interactions is of great interest due to a number of applications, and there has been significant work carried out with laser energies up to a few 100 J with 10's of femtosecond to 1 ps pulse durations. Here, we report results from an experiment at the OMEGA EP laser, where laser energy and pulse length were varied from 100 to 1250 J and 0.7–30 ps, respectively, in the moderate ([Formula: see text]) laser intensity regime. Ions and electrons were simultaneously measured from disk targets made of CH and CD by a Thomson parabola and a magnetic spectrometer, respectively. Measurements showed that the electron temperature, [Formula: see text] (MeV), has a dependence on the laser energy, [Formula: see text] (J), and pulse duration, [Formula: see text] (ps), and its empirical scaling was found to be [Formula: see text]. The maximum proton and deuteron energies are linearly dependent on the electron temperature, [Formula: see text] and [Formula: see text], respectively. A significant increase in proton numbers with the laser energy was also observed. The increase in the maximum proton energy and proton count with higher energy longer duration pulses presented in this article shows that such laser conditions have a great advantage for applications, such as the proton radiograph, in the moderate laser intensity regime.

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Simpson, R. A., D. A. Mariscal, J. Kim, G. G. Scott, G. J. Williams, E. Grace, C. McGuffey et al. « Demonstration of TNSA proton radiography on the National Ignition Facility Advanced Radiographic Capability (NIF-ARC) laser ». Plasma Physics and Controlled Fusion 63, n^o 12 (12 novembre 2021) : 124006. http://dx.doi.org/10.1088/1361-6587/ac2349.

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Abstract Proton radiography using short-pulse laser drivers is an important tool in high-energy density (HED) science for dynamically diagnosing key characteristics in plasma interactions. Here we detail the first demonstration of target-normal sheath acceleration (TNSA)-based proton radiography the NIF-ARC laser system aided by the use of compound parabolic concentrators (CPCs). The multi-kJ energies available at the NIF-ARC laser allows for a high-brightness proton source for radiography and thus enabling a wide range of applications in HED science. In this demonstration, proton radiography of a physics package was performed and this work details the spectral properties of the TNSA proton probe as well as description of the resulting radiography quality.

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Cutroneo, Mariapompea, Lorenzo Torrisi, Jan Badziak, Marcin Rosinski, Vladimir Havranek, Anna Mackova, Petr Malinsky et al. « Graphite oxide based targets applied in laser matter interaction ». EPJ Web of Conferences 167 (2018) : 02004. http://dx.doi.org/10.1051/epjconf/201816702004.

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In the present work, we propose the production of a hybrid graphene based material suitable to be laser irradiated with the aim to produce quasi-monoenergetic proton beams using a femtosecond laser system. The unique lattice structure of the irradiated solid thin target can affect the inside electron propagation, their outgoing from the rear side of a thin foil, and subsequently the plasma ion acceleration. The produced targets, have been characterized in composition, roughness and structure and for completeness irradiated. The yield and energy of the ions emitted from the laser-generated plasma have been monitored and the emission of proton stream profile exhibited an acceleration of the order of several MeVs/charge state.

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Weichman, K., A. P. L. Robinson, M. Murakami, J. J. Santos, S. Fujioka, T. Toncian, J. P. Palastro et A. V. Arefiev. « Progress in relativistic laser–plasma interaction with kilotesla-level applied magnetic fields ». Physics of Plasmas 29, n^o 5 (mai 2022) : 053104. http://dx.doi.org/10.1063/5.0089781.

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We report on progress in the understanding of the effects of kilotesla-level applied magnetic fields on relativistic laser–plasma interactions. Ongoing advances in magnetic-field–generation techniques enable new and highly desirable phenomena, including magnetic-field–amplification platforms with reversible sign, focusing ion acceleration, and bulk-relativistic plasma heating. Building on recent advancements in laser–plasma interactions with applied magnetic fields, we introduce simple models for evaluating the effects of applied magnetic fields in magnetic-field amplification, sheath-based ion acceleration, and direct laser acceleration. These models indicate the feasibility of observing beneficial magnetic-field effects under experimentally relevant conditions and offer a starting point for future experimental design.

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NAIK, P. A., et P. D. GUPTA. « STUDIES PLANNED AT CAT, INDORE ON LASER-PLASMA BASED ELECTRON ACCELERATION ». International Journal of Modern Physics B 21, n^o 03n04 (10 février 2007) : 459–63. http://dx.doi.org/10.1142/s0217979207042240.

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The Laser Plasma Division at the Centre for Advanced Technology is engaged in a variety of research and development activities on laser-plasma interaction with special emphasis on laser-matter interaction at ultra-high intensities. An important aspect of our future work is studies in laser-plasma based acceleration using an elaborate infrastructural set-up of ultra-fast laser and plasma diagnostic systems and recently acquired 10TW, 50fs Ti :Sapphire laser system. This paper presents outline of the planned studies in this field.

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Göthel, Ilja, Constantin Bernert, Michael Bussmann, Marco Garten, Thomas Miethlinger, Martin Rehwald, Karl Zeil et al. « Optimized laser ion acceleration at the relativistic critical density surface ». Plasma Physics and Controlled Fusion 64, n^o 4 (28 février 2022) : 044010. http://dx.doi.org/10.1088/1361-6587/ac4e9f.

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Abstract An effort to achieve high-energetic ion beams from the interaction of ultrashort laser pulses with a plasma, volumetric acceleration mechanisms beyond target normal sheath acceleration have gained attention. A relativistically intense laser can turn a near critical density plasma slowly transparent, facilitating a synchronized acceleration of ions at the moving relativistic critical density front. While simulations promise extremely high ion energies in this regime, the challenge resides in the realization of a synchronized movement of the ultra-relativistic laser pulse ( a 0 ≳ 30) driven reflective relativistic electron front and the fastest ions, which imposes a narrow parameter range on the laser and plasma parameters. We present an analytic model for the relevant processes, confirmed by a broad parameter simulation study in 1D- and 3D-geometry. By tailoring the pulse length and plasma density profiles at the front side, we can optimize the proton acceleration performance and extend the regions in parameter space of efficient ion acceleration at the relativistic density surface.

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Caridi, F., L. Torrisi, D. Margarone et A. Borrielli. « Investigations on low temperature laser-generated plasmas ». Laser and Particle Beams 26, n^o 2 (6 mai 2008) : 265–71. http://dx.doi.org/10.1017/s0263034608000311.

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AbstractA nanosecond pulsed Nd-Yag laser, operating at an intensity of about 109 W/cm2, was employed to irradiate different metallic solid targets (Al, Cu, Ta, W, and Au) in vacuum. The measured ablation yield increases with the direct current (dc) electrical conductivity of the irradiated target. The produced plasma was characterized in terms of thermal and Coulomb interaction evaluating the ion temperature and the ion acceleration voltage developed in the non-equilibrium plasma core. The particles emission produced along the normal to the target surface was investigated measuring the neutral and the ion energy distributions and fitting the experimental data with the “Coulomb-Boltzmann-shifted” function. Results indicate that the mean energy of the distributions and the equivalent ion acceleration voltage of the non-equilibrium plasma increase with the free electron density of the irradiated element.

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Gamaly, E. G. « Ultrashort powerful laser matter interaction : Physical problems, models, and computations ». Laser and Particle Beams 12, n^o 2 (juin 1994) : 185–208. http://dx.doi.org/10.1017/s0263034600007680.

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The different physical models, computational methods, and results describing the properties of a plasma produced by an ultrashort laser pulse interacting with a solid target at different laser intensities are presented. The basic issues affecting the laser-plasma interaction are considered, including: the different absorption mechanisms; the formation of a transient, nonequilibrium, asymmetric electron distribution function; the energy losses; the role of instabilities and the ponderomotive force; ion expansion and acceleration; and surface wave propagation along the boundary of the plasma. The article concludes with a discussion of the range of applicability of the different approximations and future perspectives for the field.

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Varmazyar, Parvin, Saeed Mirzanejhad et Taghi Mohsenpour. « Effect of pre-plasma on the ion acceleration by intense ultra-short laser pulses ». Laser and Particle Beams 36, n^o 2 (juin 2018) : 226–31. http://dx.doi.org/10.1017/s0263034618000241.

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AbstractIn the interaction of short-laser pulses with a solid density target, pre-plasma can play a major role in ion acceleration processes. So far, complete analysis of pre-plasma effect on the ion acceleration by ultra-short laser pulses in the radiation pressure acceleration (RPA) regime has been unknown. Then the effect of pre-plasma on the ion acceleration efficiency is analyzed by numerical results of the particle-in-cell simulation in the RPA regime. It is shown that, for long-laser pulses (τp > 50 fs), the presence of pre-plasma makes a destructive effect on ion acceleration while it may have a contributing effect for short-laser pulses (τp < 50 fs). Therefore, the 35 fs (20 fs) laser pulse can accelerate ions up to 40 MeV (55 eV), which is almost two (three) times larger in energy rather than use of a 100 fs pulse with the same pre-plasma scale length.

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POMMIER, LAURENT, et ERIK LEFEBVRE. « Simulations of energetic proton emission in laser–plasma interaction ». Laser and Particle Beams 21, n^o 4 (octobre 2003) : 573–81. http://dx.doi.org/10.1017/s0263034603214166.

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Energetic protons are emitted from thin foils irradiated by short laser pulses at high intensities. One- and two-dimensional particle-in-cell simulations have been used to study the influence of initial proton position, laser irradiance, and target density profile on this ion acceleration. These simulations bring additional support to the idea that protons are mainly accelerated from the rear side of the target, by electrostatic fields associated with hot electrons escaping into vacuum. The density scale length at the front of the target appears to be the main parameter to increase proton energies when the laser irradiance is fixed.

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Zhou, Ge, Wei-Min Wang, Yutong Li et Jie Zhang. « Enhanced hot electron generation via laser interference ». Physics of Plasmas 29, n^o 5 (mai 2022) : 052704. http://dx.doi.org/10.1063/5.0076203.

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The interaction of two interfered picosecond laser pulses with overdense plasma and the resulting hot electron generation are studied by particle-in-cell simulation. We find that the yield and temperature of forward hot electrons can be significantly increased when laser interference fringes have a period around [Formula: see text] and the angle between the two pulses is about [Formula: see text]. The enhancements result from local intensity increase at laser interference fringes and the plasma surface structure formed by laser pulses. The optimal angle and fringe period are analyzed, and the dependence between the optimal period and plasma density scale length is discussed. This work could be applied in hot electron generation and the resulting ion acceleration, fast ignition of laser fusion, etc.

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Tayyab, M., S. Bagchi, J. A. Chakera, D. K. Avasthi, R. Ramis, A. Upadhyay, B. Ramakrishna, T. Mandal et P. A. Naik. « Mono-energetic heavy ion acceleration from laser plasma based composite nano-accelerator ». Physics of Plasmas 25, n^o 12 (décembre 2018) : 123102. http://dx.doi.org/10.1063/1.5053640.

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Psikal, J., O. Klimo et J. Limpouch. « Simulations of femtosecond laser pulse interaction with spray target ». Laser and Particle Beams 32, n^o 1 (28 janvier 2014) : 145–56. http://dx.doi.org/10.1017/s0263034614000032.

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AbstractLaser interactions with spray targets (clouds of submicron droplets) are studied here via numerical simulations using two-dimensional particle-in-cell codes. Our simulations demonstrate an efficient absorption of laser pulse energy inside the spray. The energy absorption efficiency depends on the inter-droplet distance, size of the cloud of droplets, and laser pulse intensity, as well as on the pre-evaporation of droplets due to laser pulse pedestal. We investigate in detail proton acceleration from the spray. Energy spectra of protons in various acceleration directions vary significantly depending on the density profile of the plasma created from the droplets and on laser intensity. The spray target can be alternative of foil targets for high intensity high repetition ultrahigh contrast femtosecond lasers. However, at intensities >1021 W/cm2, the efficiency of laser absorption and ion acceleration from the droplets drops significantly in contrast to foils.

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MIYAZAKI, SHUJI, NOBUYASU OKAZAKI, RYO SONOBE, QING KONG, SHIGEO KAWATA, A. A. ANDREEV et JIRI LIMPOUCH. « Ion focusing effect of electron cloud produced by laser-plasma interaction ». Laser and Particle Beams 24, n^o 1 (mars 2006) : 157–61. http://dx.doi.org/10.1017/s0263034606060228.

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We propose a focusing mechanism of high-energy ions by an electron cloud produced by a laser interaction with slab plasma. In our 2.5-dimensional (2.5D) particle-in-cell simulations, the laser intensity is 2 × 1020 W/cm2, the laser wavelength λ is 1.053 μm, and the laser spot size is 2.5λ. When the high intensity laser irradiates slab plasma, electrons are accelerated, oscillate around the plasma and produce the electron cloud locally at the sides of the plasma. Because the electrons are localized transversely, a static electric potential is formed to focus ions and at the same time the ions are accelerated longitudinally. Though the longitudinal ion acceleration has been studied well, the ion focusing effect is reported for the first time in this paper. In our calculations, the maximum energy and intensity of the protons are 8.61 MeV and 1.89 × 1017 W/cm2, and the diameter of the proton bunch accelerated are focused to 71.2% of its initial size.

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Bari, M. A., M. Chen, W. M. Wang, Y. T. Li, M. Q. He, Z. M. Sheng et J. Zhang. « Ion acceleration in the interaction of an intense laser pulse with structured plasma ». Physica Scripta 77, n^o 6 (juin 2008) : 065502. http://dx.doi.org/10.1088/0031-8949/77/06/065502.

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MACCHI, ANDREA, et FULVIO CORNOLTI. « ION ACCELERATION USING CIRCULARLY POLARIZED PULSES : PHYSICS AND POSSIBLE APPLICATIONS ». International Journal of Modern Physics B 21, n^o 03n04 (10 février 2007) : 579–89. http://dx.doi.org/10.1142/s0217979207042380.

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The acceleration of ions in the interaction of ultrashort, high intensity, circularly polarized laser pulses with overdense plasmas has been theoretically investigated. By using particle-in-cell (PIC) simulations it is found that high-density, short duration ion bunches moving into the plasma are promptly generated at the laser-plasma interaction surface. This regime is qualitatively different from ion acceleration regimes driven by fast electrons such as sheath acceleration at the rear side of the target. A simple analytical model accounts for the numerical observations and provides scaling laws for the ion bunch velocity and generation time as a function of pulse intensity and plasma density. The ion bunches have moderate energies (100 keV-1 MeV) but very high density and low beam divergence, and might be of interest for problems of ultrafast compression, acceleration or heating of high–density matter. In particular, we have studied their application to the development of compact sources of fusion neutrons. We analyzed two target schemes showing that intense neutron bursts with femtosecond duration are produced.

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Hora, Heinrich. « Fundamental difference between picosecond and nanosecond laser interaction with plasmas : Ultrahigh plasma block acceleration links with electron collective ion acceleration of ultra-thin foils ». Laser and Particle Beams 30, n^o 2 (9 mars 2012) : 325–28. http://dx.doi.org/10.1017/s0263034611000784.

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AbstractArguments are discussed on how ion energy measurements from ultra-thin diamond irradiation with 45 fs laser pulses of 26 terawatt power may be related to the ultra-high acceleration of plasma blocks where the significance of the highly efficient direct conversion of laser radiation into mechanical motion of ions or plasma blocks is dominated by nonlinear (ponderomotive) forces in fundamental contrast to thermo-kinetic dominated interaction with ns laser pulses.

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BADZIAK, J., S. GŁOWACZ, S. JABŁOŃSKI, P. PARYS, J. WOŁOWSKI et H. HORA. « Generation of picosecond high-density ion fluxes by skin-layer laser-plasma interaction ». Laser and Particle Beams 23, n^o 2 (juin 2005) : 143–47. http://dx.doi.org/10.1017/s0263034605050238.

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The possibilities of producing ultrahigh-current-density ps ion fluxes by the skin-layer interaction of a short (≤ 1ps) laser pulse with plasma were studied using two-fluid hydrodynamic simulations, and the time-of-flight measurements. Backward-emitted ion fluxes from a massive (Au) target as well as forward-emitted fluxes from various thin foil targets irradiated by a 1-ps laser pulse of intensity up to 2 × 1017W/cm2were recorded. Both the simulations and the measurements confirmed that using the short-pulse skin-layer interaction of a laser pulse with a thin pre-plasma layer in front of a solid target, a high-density collimated ion flux of extremely high ion current density (∼ 1010A/cm2close to the target), can be generated at laser intensity only ∼ 1017W/cm2. The ion current densities produced by this way were found to be comparable to (or even higher than) those estimated from recent short-pulse experiments using a target normal sheath acceleration mechanism at relativistic laser intensities. The effect of the target structure on the current densities and energies of forward-emitted ions is demonstrated.

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Torrisi, L., G. Ceccio, N. Restuccia, E. Messina, P. G. Gucciardi et M. Cutroneo. « Laser-generated plasmas by graphene nanoplatelets embedded into polyethylene ». Laser and Particle Beams 35, n^o 2 (28 mars 2017) : 294–303. http://dx.doi.org/10.1017/s0263034617000179.

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AbstractGraphene micrometric particles have been embedded into polyethylene at different concentrations by using chemical–physical processes. The synthesized material was characterized in terms of mechanical and optical properties, and Raman spectroscopy. Obtained targets were irradiated by using a Nd:YAG laser at intensities of the order of 1010 W/cm2 to generate non-equilibrium plasma expanding in vacuum. The laser–matter interaction produces charge separation effects with consequent acceleration of protons and carbon ions. Plasma was characterized using time-of-flight measurements of the accelerated ions. Applications of the produced targets in order to generate carbon and proton ion beams from laser-generated plasma are presented and discussed.

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Chagovets, Timofej, Stanislav Stanček, Lorenzo Giuffrida, Andriy Velyhan, Maksym Tryus, Filip Grepl, Valeriia Istokskaia et al. « Automation of Target Delivery and Diagnostic Systems for High Repetition Rate Laser-Plasma Acceleration ». Applied Sciences 11, n^o 4 (13 février 2021) : 1680. http://dx.doi.org/10.3390/app11041680.

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Fast solid target delivery and plasma-ion detection systems have been designed and developed to be used in high intensity laser-matter interaction experiments. We report on recent progress in the development and testing of automated systems to refresh solid targets at a high repetition rate during high peak power laser operation (>1 Hz), along with ion diagnostics and corresponding data collection and real-time analysis methods implemented for future use in a plasma-based ion acceleration beamline for multidisciplinary user applications.

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Hora, H., G. H. Miley, M. Ghoranneviss et A. Salar Elahi. « Application of picosecond terawatt laser pulses for fast ignition of fusion ». Laser and Particle Beams 31, n^o 2 (3 mai 2013) : 249–56. http://dx.doi.org/10.1017/s026303461300013x.

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AbstractIn this research, we presented the application of picosecond terawatt laser pulses for ultrahigh acceleration of plasma blocks for fast ignition of fusion. Ultrahigh acceleration of plasma blocks after irradiation of picosecond laser pulses of around terawatt power in the range of 1020 cm/s2was discovered by Sauerbrey (1996) as measured by Doppler effect where the laser intensity was up to about 1018W/cm2. This is several orders of magnitude higher than acceleration by irradiation based on thermal interaction of lasers has produced. This ultrahigh acceleration resulted from hydrodynamic computations at plane target interaction in 1978 at comparable conditions where the interaction was dominated by the nonlinear (generalized ponderomotive) forces where the laser energy was instantly converted into plasma motion in contrast to slow and delayed thermal collision processes. After clarifying this basic result, the application of the plasma blocks for side-on ignition of solid density or modestly compressed fusion fuel following the theory of Chu (1971) is updated in view of later discovered plasma properties and the ignition of deuterium tritium and of proton-11B appeared possible for a dozen of PW-PS laser pulses if an extremely high contrast ratio avoided relativistic self-focusing. A re-evaluation of more recent experiment confirms the acceleration by the nonlinear force, and the generation of the fusion flame with properties of Rankine-Hugoniot shocks is reported.

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Hakimi, Sahel, Lieselotte Obst-Huebl, Axel Huebl, Kei Nakamura, Stepan S. Bulanov, Sven Steinke, Wim P. Leemans et al. « Laser–solid interaction studies enabled by the new capabilities of the iP2 BELLA PW beamline ». Physics of Plasmas 29, n^o 8 (août 2022) : 083102. http://dx.doi.org/10.1063/5.0089331.

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The new capabilities of the short focal length, high intensity beamline, named iP2, at the BELLA Center will extend the reach of research in high energy density science, including accessing new regimes of high gradient ion acceleration and their applications. This 1 Hz system will provide an on-target peak intensity beyond [Formula: see text] with a temporal contrast ratio of <[Formula: see text] that will be enabled by the addition of an on-demand double plasma mirror setup. An overview of the beamline design and the main available diagnostics are presented in this paper as well as a selection of accessible research areas. As a demonstration of the iP2 beamline's capabilities, we present 3D particle-in-cell simulations of ion acceleration in the magnetic vortex acceleration regime. The simulations were performed with pure hydrogen targets and multi-species targets. Proton beams with energy up to 125 MeV and an approximately 12° full angle emission are observed as preplasma scale length and target tilt are varied. The number of accelerated protons is on the order of 109/MeV/sr for energies above 60 MeV.

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Ning, Li, Mu Jie et Kong Fancun. « Numerical Studies on Bow Waves in Intense Laser-Plasma Interaction ». Laser and Particle Beams 2023 (15 février 2023) : 1–11. http://dx.doi.org/10.1155/2023/9414451.

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Laser-driven wakefield acceleration (LWFA) has attracted lots of attention in recent years. However, few writers have been able to make systematic research into the bow waves generated along with the wake waves. Research about the bow waves will help to improve the understanding about the motion of the electrons near the wake waves. In addition, the relativistic energetic electron density peaks have great potential in electron acceleration and reflecting flying mirrors. In this paper, the bow waves generated in laser-plasma interactions as well as the effects of different laser and plasma parameters are investigated. Multidimensional particle-in-cell simulations are made to present the wake waves and bow waves by showing the electron density and momentum distribution as well as the electric field along x and y directions. The evolution of the bow wave structure is investigated by measuring the open angle between the bow wave and the wake wave cavity. The angle as well as the peak electron density and transverse momentum is demonstrated with respect to different laser intensities, spot sizes, plasma densities, and preplasma lengths. The density peak emits high-order harmonics up to 150 orders and can be a new kind of “flying mirror” to generate higher order harmonics. The study on the bow waves is important for further investigation on the electron motion around the wake waves, generation of dense electron beams, generation of high-order harmonics, and other research and applications based on the bow waves.

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Stumpf, M., M. Melchger, S. Montag et G. Pretzler. « Multiparameter-controlled laser ionization within a plasma wave for wakefield acceleration ». Journal of Physics B : Atomic, Molecular and Optical Physics 55, n^o 1 (5 janvier 2022) : 015401. http://dx.doi.org/10.1088/1361-6455/ac489b.

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Abstract We present an optical setup for well-defined ionization inside a plasma such that precisely controlled spots of high electron density can be generated. We propose to use the setup for Trojan Horse Injection (or Plasma Photocathode Emission) where a collinear laser beam is needed to release electrons inside a plasma wakefield. The reflection-based setup allows a suitable manipulation of the laser near field without disturbing the spectral phase of the laser pulses. A required ionization state and volume can be reached by tuning the beam size, pulse duration and pulse energy. The ionization simulations enable a prediction of the ionization spot and are in good agreement with dedicated experiments which measured the number of electrons created during the laser–gas interaction.

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Nersisyan, H. B., et C. Deutsch. « Stopping of ions in a plasma irradiated by an intense laser field ». Laser and Particle Beams 29, n^o 4 (4 octobre 2011) : 389–97. http://dx.doi.org/10.1017/s0263034611000486.

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AbstractThe inelastic interaction between heavy ions and an electron plasma in the presence of an intense radiation field (RF) is investigated. The stopping power of the test ion averaged with a period of the RF has been calculated assuming that ω0 > ωp, where ω0 is the frequency of the RF and ωp is the plasma frequency. In order to highlight the effect of the radiation field we present a comparison of our analytical and numerical results obtained for nonzero RF with those for vanishing RF. It has been shown that the RF may strongly reduce the mean energy loss for slow ions while increasing it at high–velocities. Moreover, it has been shown, that acceleration of the projectile ion due to the RF is expected at high–velocities and in the high–intensity limit of the RF, when the quiver velocity of the plasma electrons exceeds the ion velocity.

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OSMAN, F., YU CANG, H. HORA, LI-HUA CAO, HONG LIU, XIANTU HE, J. BADZIAK et al. « Skin depth plasma front interaction mechanism with prepulse suppression to avoid relativistic self-focusing for high-gain laser fusion ». Laser and Particle Beams 22, n^o 1 (mars 2004) : 83–87. http://dx.doi.org/10.1017/s0263034604221164.

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Measurements of the ion emission from targets irradiated with neodymium glass and iodine lasers were analyzed and a very significant anomaly observed. The fastest ions with high charge number Z, which usually are of megaelectron volt energy following the relativistic self-focusing and nonlinear-force acceleration theory, were reduced to less than 50 times lower energies when 1.2 ps laser pulses of about 1 J were incident. We clarify this discrepancy by the model of skin depth plasma front interaction in contrast to the relativistic self-focusing with filament generation. This was indicated also from the unique fact that the ion number was independent of the laser intensity. The skin layer theory prescribes prepulse control and lower (near relativistic threshold) laser intensities for nonlinear-force-driven plasma blocks for high-gain ignition similar to light ion beam fusion.

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Bin, J. H., A. L. Lei, X. Q. Yang, L. G. Huang, M. Y. Yu, Wei Yu et K. A. Tanaka. « Quasi-monoenergetic proton beam generation from a double-layer solid target using an intense circularly polarized laser ». Laser and Particle Beams 27, n^o 3 (17 juillet 2009) : 485–90. http://dx.doi.org/10.1017/s0263034609990218.

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AbstractMonoenegetic ion beam generation from circularly polarized laser-pulse interaction with a double-layer target is considered. The front layer consists of heavy-ion plasma, and the rear layer is a small thin coating of light-ion plasma. Particle-in-cell simulation shows that the multi-dimensional effects in the ion radiation pressure acceleration are avoided and a highly monoenergetic light-ion beam can be produced. Our simulations reveal that the charge-mass ratio of heavy ions in the front layer and the thicknesses of both layers can strongly affect the proton energy spectra.

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Lalousis, P., I. B. Földes et H. Hora. « Ultrahigh acceleration of plasma by picosecond terawatt laser pulses for fast ignition of fusion ». Laser and Particle Beams 30, n^o 2 (9 mars 2012) : 233–42. http://dx.doi.org/10.1017/s0263034611000875.

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AbstractA fundamental different mechanism dominates laser interaction with picosecond-terawatt pulses in contrast to the thermal-pressure processes with ns pulses. At ps-interaction, the thermal effects are mostly diminished and the nonlinear (ponderomotive) forces convert laser energy instantly with nearly 100% efficiency into the space charge neutral electron cloud, whose motion is determined by the inertia of the attached ion cloud. These facts were realized only by steps in the past and are expressed by the ultrahigh plasma acceleration, which is more than few thousand times higher than observed by any thermokinetic mechanism. The subsequent application for side-on ignition of uncompressed fusion fuel by the ultrahigh accelerated plasma blocks is studied for the first time by using the genuine two-fluid hydrodynamics. Details of the shock-like flame propagation can be evaluated for the transition to ignition conditions at velocities near 2000 km/s for solid deuterium-tritium.

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GIULIETTI, D., E. BRESCHI, M. GALIMBERTI, A. GIULIETTI, L. A. GIZZI, P. KOESTER, L. LABATE et al. « HIGH BRIGHTNESS LASER INDUCED MULTI-MEV ELECTRON/PROTON SOURCES ». International Journal of Modern Physics A 22, n^o 22 (10 septembre 2007) : 3810–25. http://dx.doi.org/10.1142/s0217751x07037445.

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The chirped pulse amplification (CPA) technique has opened new perspectives in the radiation-matter interaction studies using ultra-short laser pulses at ultra-relativistic intensities. In particular the original idea, proposed by Tajima and Dawson, of accelerating electrons by the huge electric fields of plasma waves which develop in the wake of a laser pulse propagating in a plasma, become feasible. Some laboratories all over the world have produced by such a technique collimated electron busts of hundreds of MeV along acceleration lengths of a few hundreds of microns. In other experiments, using thin solid targets, intense bursts of energetic protons have been at the same time detected. The proton acceleration mechanism is essentially based on the Coulomb force appearing at the thin solid target surface as a consequence of the previous escape of the energetic electrons from the target. In the paper some experimental results will be presented as well as the opportunities the INFN PLASMONX project will offer in this research field at LNF.

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Liu, Shaojie, Chenhui Lu, Zhengquan Fan, Shixiang Wang, Peiyan Li, Xinhou Chen, Jun Pan, Yong Xu, Yi Liu et Xiaojun Wu. « Modulated terahertz generation in femtosecond laser plasma filaments by high-field spintronic terahertz pulses ». Applied Physics Letters 120, n^o 17 (25 avril 2022) : 172404. http://dx.doi.org/10.1063/5.0080234.

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Strong-field terahertz (THz) light-matter interaction provides various nonlinear control approaches in condensed matter physics, energy and material sciences, electron acceleration, and manipulation. Recently developed spintronic THz emission with minimum complexities has been demonstrated to have the capability for generating high field strengths. Up to now, nonlinear applications based on the spintronic THz transients have yet been realized. Here, we report THz emission from two-color femtosecond laser plasma filaments modulated by a 60-kV/cm THz pulse from W/CoFeB/Pt heterostructures. Enhanced THz radiation based on electron acceleration in plasma is recorded when the direction of the spintronic THz modulating field is in line with that of the electron movement. This behavior is quantitatively reproduced by a local current model of the plasma THz source. Our experimental and theoretical results may inspire further nonlinear THz investigation and accelerate ultrafast THz engineering in matter.

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CANG, Y., F. OSMAN, H. HORA, J. ZHANG, J. BADZIAK, J. WOLOWSKI, K. JUNGWIRTH, K. ROHLENA et J. ULLSCHMIED. « Computations for nonlinear force driven plasma blocks by picosecond laser pulses for fusion ». Journal of Plasma Physics 71, n^o 1 (13 janvier 2005) : 35–51. http://dx.doi.org/10.1017/s0022377804002983.

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The concept of the fast ignitor for laser fusion has led to some modifications in applying petawatt-picosecond (PW-ps) laser-produced high intensity particle beams to ignite deuterium-tritium (DT) fuel. Some very anomalous measurements of ion emission from targets irradiated by picosecond laser pulses led to the development of a skin depth interaction scheme where a defined control of prepulses is necessary. Based on these experimental facts, we have applied a one-dimensional two-fluid hydrodynamic code to understand how the nonlinear ponderomotive force generates two plasma blocks, one moving against the laser light (ablation) and the other moving into the target. This compressed block produces an ion current density of above 10$^{11}$ A cm$^{-2}$ and an ion energy of about 100 keV. This may be a rather promising option to use PW-ps laser pulses for igniting fusion in solid density DT fuel, realizing very high gain controlled fusion reactions.

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Shoucri, M., X. Lavocat-Dubuis, J. P. Matte et F. Vidal. « Numerical study of ion acceleration and plasma jet formation in the interaction of an intense laser beam normally incident on an overdense plasma ». Laser and Particle Beams 29, n^o 3 (11 juillet 2011) : 315–32. http://dx.doi.org/10.1017/s026303461100036x.

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AbstractWe present a numerical study of the acceleration of ions in the interaction of a high intensity circularly polarized laser beam normally incident on an overdense plasma target, and the subsequent formation of neutral plasma ejected toward the rear side of the target. We compare the results obtained from two different numerical codes. We use an Eulerian Vlasov code for the numerical solution of the one-dimensional relativistic Vlasov-Maxwell set of equations, for both electrons and ions, and a particle-in-cell code applied to the same problem. We consider the case when the laser free space wavelength λ0 is greater than the scale length of the jump in the plasma density at the target plasma edge Ledge (λ0 ≫ Ledge), and the ratio of the plasma density to the critical density is such that n/ncr ≫ 1. The ponderomotive pressure due to the incident high-intensity laser radiation pushes the electrons at the target plasma surface, producing a sharp density gradient at the plasma surface, which gives rise to a charge separation. The resulting electric field accelerates the ions that reach a free streaming expansion phase, where they are neutralized by the electrons. A neutral plasma jet is thus ejected toward the rear side of the target. Two cases are studied: In the first case, the laser intensity rises to a maximum and then remains constant, and in the second case, the laser intensity is a Gaussian-shaped pulse. The results show substantial differences in the phase-space structure of the ions and the electrons between these two cases. There is good agreement between the quantitative macroscopic results obtained by the two codes, and good qualitative agreement between the results showing the kinetic details of the phase-space structures. The low noise level of the Eulerian Vlasov code allows a more detailed representation of the phase-space structures associated with this system, especially in the low density regions of the phase-space where ions are accelerated.

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Prasad, R., R. Singh et V. K. Tripathi. « Effect of an axial magnetic field and ion space charge on laser beat wave acceleration and surfatron acceleration of electrons ». Laser and Particle Beams 27, n^o 3 (24 juin 2009) : 459–64. http://dx.doi.org/10.1017/s0263034609990127.

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AbstractThe presence of an axial magnetic field in a laser beat wave accelerator enhances the oscillatory velocity of electrons due to cyclotron resonance effect leading to higher amplitude of the ponderomotive force driven plasma wave, and higher energy of accelerating electrons. The axial magnetic field inhibits the transverse escape of electrons and thus causes a growth of the interaction length. The surfatron acceleration of electrons also shows a similar enhancement. A surfatron transverse magnetic field deflects the electrons parallel to the phase fronts of the accelerating wave keeping them in phase with it. However, the electron continues to move away radially.

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Sidorov, I. A., et A. B. Savel’ev. « Numerical 1D PIC-simulations of ion acceleration during laser-plasma interaction : Optimization of a two-component multilayered target structure ». Plasma Physics Reports 36, n^o 13 (décembre 2010) : 1107–11. http://dx.doi.org/10.1134/s1063780x10130040.

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Li, Dongyu, Tang Yang, Minjian Wu, Zhusong Mei, Kedong Wang, Chunyang Lu, Yanying Zhao et al. « Introduction of Research Work on Laser Proton Acceleration and Its Application Carried out on Compact Laser–Plasma Accelerator at Peking University ». Photonics 10, n^o 2 (28 janvier 2023) : 132. http://dx.doi.org/10.3390/photonics10020132.

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Laser plasma acceleration has made remarkable progress in the last few decades, but it also faces many challenges. Although the high gradient is a great potential advantage, the beam quality of the laser accelerator has a certain gap, or it is different from that of traditional accelerators. Therefore, it is important to explore and utilize its own features. In this article, some recent research progress on laser proton acceleration and its irradiation application, which was carried out on the compact laser plasma accelerator (CLAPA) platform at Peking University, have been introduced. By combining a TW laser accelerator and a monoenergetic beamline, proton beams with energies of less than 10 MeV, an energy spread of less than 1%, and with several to tens of pC charge, have been stably produced and transported in CLAPA. The beamline is an object–image point analyzing system, which ensures the transmission efficiency and the energy selection accuracy for proton beams with large initial divergence angle and energy spread. A spread-out Bragg peak (SOBP) is produced with high precision beam control, which preliminarily proved the feasibility of the laser accelerator for radiotherapy. Some application experiments based on laser-accelerated proton beams have also been carried out, such as proton radiograph, preparation of graphene on SiC, ultra-high dose FLASH radiation of cancer cells, and ion-beam trace probes for plasma diagnosis. The above applications take advantage of the unique characteristics of laser-driven protons, such as a micron scale point source, an ultra-short pulse duration, a wide energy spectrum, etc. A new laser-driven proton therapy facility (CLAPA II) is being designed and is under construction at Peking University. The 100 MeV proton beams will be produced via laser–plasma interaction by using a 2-PW laser, which may promote the real-world applications of laser accelerators in malignant tumor treatment soon.

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Kwon, Duck-Hee, Yong-Joo Rhee, Sungman Lee et Hyungki Cha. « Effect of plasma profile on ion acceleration in the interaction of a short laser pulse with a thin overdense target ». Physics of Plasmas 15, n^o 6 (juin 2008) : 064503. http://dx.doi.org/10.1063/1.2937819.

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Kantarelou, Vasiliki, Andriy Velyhan, Przemysław Tchórz, Marcin Rosiński, Giada Petringa, Giuseppe Antonio Pablo Cirrone, Valeriia Istokskaia et al. « A Methodology for the Discrimination of Alpha Particles from Other Ions in Laser-Driven Proton-Boron Reactions Using CR-39 Detectors Coupled in a Thomson Parabola Spectrometer ». Laser and Particle Beams 2023 (27 février 2023) : 1–12. http://dx.doi.org/10.1155/2023/3125787.

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Solid-state nuclear track detectors (CR-39 type) are frequently used for the detection of ions accelerated by laser-plasma interaction because they are sensitive to each single particle. To the present day, CR-39 detectors are the main diagnostics in experiments focused on laser-driven proton-boron (p11B) fusion reactions to detect alpha particles, which are the main products of such a nuclear reaction, and to reconstruct their energy distribution. However, the acceleration of multispecies ions in the laser-generated plasma makes this spectroscopic method complex and often does not allow to unambiguously discriminate the alpha particles generated from p11B fusion events from the laser-driven ions. In this experimental work, performed at the PALS laser facility (600 J, 300 ps, laser intensity 1016 W/cm2), CR-39 detectors were used as main detectors for the angular distribution of the produced alpha particles during a p11B fusion dedicated experimental campaign. Additionally, a CR-39 detector was set inside a Thomson Parabola (TP) spectrometer with the aim to calibrate the CR-39 response for low energetic laser-driven ions originating from the plasma in the given experimental conditions. The detected ion energies were ranging from hundreds of keV to a few MeV, and the ion track diameters were measured for etching times up to 9 hours. The goal of the test was the evaluation of the detectors’ ability to discriminate the alpha particles from the aforementioned ions. Within this study, the calibration curves for protons and silicon low energy ions are accomplished, the overlapping of the proton tracks and alpha particles is verified, and a methodology to avoid this problem is realized.

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SARI, AMIR H., F. OSMAN, K. R. DOOLAN, M. GHORANNEVISS, H. HORA, R. HÖPFL, G. BENSTETTER et M. H. HANTEHZADEH. « Application of laser driven fast high density plasma blocks for ion implantation ». Laser and Particle Beams 23, n^o 4 (octobre 2005) : 467–73. http://dx.doi.org/10.1017/s0263034605050652.

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The measurement of very narrow high density plasma blocks of high ion energy from targets irradiated with ps-TW laser pulses based on a new skin depth interaction process is an ideal tool for application of ion implantation in materials, especially of silicon, GaAs, or conducting polymers, for micro-electronics as well as for low cost solar cells. A further application is for ion sources in accelerators with most specifications of many orders of magnitudes advances against classical ion sources. We report on near band gap generation of defects by implantation of ions as measured by optical absorption spectra. A further connection is given for studying the particle beam transforming of n-type semiconductors into p-type and vice versa as known from sub-threshold particle beams. The advantage consists in the use of avoiding aggressive or rare chemical materials when using the beam techniques for industrial applications.

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HORA, HEINRICH. « New aspects for fusion energy using inertial confinement ». Laser and Particle Beams 25, n^o 1 (28 février 2007) : 37–45. http://dx.doi.org/10.1017/s0263034607070073.

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Magnetic confinement fusion (MCF) based on neutral particle beam irradiation reached the highest gains with JET and is discussed in relation to the ITER project for a possible re-orientation with respect to the ignition process. Ignition plays a similar role for inertial confinement fusion (ICF). After a short review about specific ICF developments, the fast igniter development offered a re-consideration of igniting DT fuel at modest or low compression. The observation of extreme anomalies (Sauerbrey 1996, Zhanget al., 1998 and Badziaket al., 1999) at interaction of picosecond (ps) laser pulses above TW power could be explained as a skin layer mechanism based on earlier computations (Horaet al., 2002) with nonlinear (ponderomotive) force acceleration. The resulting very high ion current density space charge neutral plasma blocks interacting as pistons to ignite DT may lead to a new scheme of laser fusion with low cost energy generation.

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Ghoranneviss, M., B. Malekynia, H. Hora, G. H. Miley et X. He. « Inhibition factor reduces fast ignition threshold for laser fusion using nonlinear force driven block acceleration ». Laser and Particle Beams 26, n^o 1 (mars 2008) : 105–12. http://dx.doi.org/10.1017/s026303460800013x.

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AbstractFast ignition for fusion energy by using petawatt-picosecond (PW-ps) laser pulses was modified due to an anomaly based on extremely clean suppression of prepulses. The resulting plasma blocks with space charge neutral ion current densities above 1011Amp/cm2may be used to ignite deuterium-tritium at densities at or little above solid state density. The difficulty is to produce extremely high energy flux densities of the blocks. Results are reported how the threshold can be reduced by a factor up to fife if the inhibition factor for thermal conductivity due to electric double layers is included in the hydrodynamic analysis.

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Yazdani, E., Y. Cang, R. Sadighi-Bonabi, H. Hora et F. Osman. « Layers from initial Rayleigh density profiles by directed nonlinear force driven plasma blocks for alternative fast ignition ». Laser and Particle Beams 27, n^o 1 (23 janvier 2009) : 149–56. http://dx.doi.org/10.1017/s0263034609000214.

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AbstractMeasurement of extremely new phenomena during the interaction of laser pulses with terawatt and higher power and picoseconds with plasmas arrived at drastically different anomalies in contrast to the usual observations if the laser pulses were very clean with a contrast ratio higher than 108. This was guaranteed by the suppression of prepulses during less than dozens of ps before the arrival of the main pulse resulting in the suppression of relativistic self-focusing. This anomaly was confirmed in many experimental details, and explained and numerically reproduced as a nonlinear force acceleration of skin layers generating quasi-neutral plasma blocks with ion current densities above 1011A/cm2. This may support the requirement to produce a fast ignition deuterium tritium fusion at densities not much higher than the solid state by a single shot PW-ps laser pulse. With the aim to achieve separately studied ignition conditions, we are studying numerically how the necessary nonlinear force accelerated plasma blocks may reach the highest possible thickness by using optimized dielectric properties of the irradiated plasma. The use of double Rayleigh initial density profiles results in many wavelength thick low reflectivity directed plasma blocks of modest temperatures. Results of computations with the genuine two-fluid model are presented.

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Hora, H., G. H. Miley, K. Flippo, P. Lalousis, R. Castillo, X. Yang, B. Malekynia et M. Ghoranneviss. « Review about acceleration of plasma by nonlinear forces from picoseond laser pulses and block generated fusion flame in uncompressed fuel ». Laser and Particle Beams 29, n^o 3 (septembre 2011) : 353–63. http://dx.doi.org/10.1017/s0263034611000413.

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AbstractIn addition to the matured “laser inertial fusion energy” with spherical compression and thermal ignition of deuterium-tritium (DT), a very new alternative for the fast ignition scheme may have now been opened by using side-on block ignition aiming beyond the DT-fusion with igniting the neutron-free reaction of proton-boron-11 (p-11B). Measurements with laser pulses of terawatt power and ps duration led to the discovery of an anomaly of interaction, if the prepulses are cut off by a factor 108(contrast ratio) to avoid relativistic self focusing in agreement with preceding computations. Applying this to petawatt (PW) pulses for Bobin-Chu conditions of side-on ignition of solid fusion fuel results after several improvements in energy gains of 10,000. This is in contrast to the impossible laser-ignition of p-11B by the usual spherical compression and thermal ignition. The side-on ignition is less than ten times only more difficult than for DT ignition. This is essentially based on the instant and direct conversion the optical laser energy by the nonlinear force into extremely high plasma acceleration. Genuine two-fluid hydrodynamic computations for DT are presented showing details how ps laser pulses generate a fusion flame in solid state density with an increase of the density in the thin flame region. Densities four times higher are produced automatically confirming a Rankine-Hugoniot shock wave process with an increasing thickness of the shock up to the nanosecond range and a shock velocity of 1500 km/s which is characteristic for these reactions.

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Williams, R. L., C. E. Clayton, C. Joshi, T. Katsouleas et W. B. Mori. « Studies of relativistic wave–particle interactions in plasma-based collective accelerators ». Laser and Particle Beams 8, n^o 3 (septembre 1990) : 427–49. http://dx.doi.org/10.1017/s0263034600008673.

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The interaction of externally injected charged particles (electrons) with plasma waves moving with a phase velocity that is very close to the speed of light is examined. Such plasma waves form the basis of at least three collective accelerator schemes: the plasma beat wave accelerator (PBWA), the plasma wake-field accelerator (PWFA), and the laser wake-field accelerator (LWFA). First, the electron trapping threshold, energy gain and acceleration length are examined using a 1-D model. This model elucidates how the final energies of the injected test electrons depend upon their injection and extraction phases and phase slippage. Phase energy diagrams are shown to be extremely useful in visualizing wave-particle interactions in 1-D. Second, we examine, using a two-dimensional model, the effects of radial electric fields on focusing or defocusing the injected particles depending upon their radial positions and phases in the relativistically moving potential well. Finally, we extend the model to 3-D so that the effect of injected particles' emittance on the acceleration process may be determined. This simple 3-D model will be extremely useful in predicting the electron energy spectra of several current experiments designed to demonstrate ultrahigh gradient acceleration of externally injected test particles by relativistic plasma waves.

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Krása, J., P. Parys, L. Velardi, A. Velyhan, L. Ryć, D. Delle Side et V. Nassisi. « Time-of-flight spectra for mapping of charge density of ions produced by laser ». Laser and Particle Beams 32, n^o 1 (29 octobre 2013) : 15–20. http://dx.doi.org/10.1017/s0263034613000797.

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AbstractA space-resolved charge density of ions is derived from a time-resolved current of ions emitted from laser-produced plasma and expanded into the vacuum along collision-free and field-free paths. This derivation is based on a similarity relationship for ion currents with “frozen” charges observed at different distances from the target. This relationship makes it possible to determine a map of ion charge density at selected times after the laser plasma interaction from signals of time-of-flight detectors positioned at a certain distance from the target around a target-surface normal. In this work, we present maps of the charge density of ions emitted from Cu and polyethylene plasmas. The mapping demonstrates that bursts of ions are emitted at various ejection angles ϕn with respect to the target-surface normal. There are two basic directions ϕ1 and ϕ2, one belonging to the fastest ions, i.e., protons and carbon ions, and the other one to the slowest ions being a part of each plasma plume.

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Salvadori, M., P. L. Andreoli, M. Cipriani, G. Cristofari, R. De Angelis, S. Malko, L. Volpe et al. « Time-of-flight methodologies with large-area diamond detectors for the effectively characterization of tens MeV protons ». Journal of Instrumentation 17, n^o 04 (1 avril 2022) : C04005. http://dx.doi.org/10.1088/1748-0221/17/04/c04005.

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Abstract A novel detector based on a polycrystalline diamond sensor is here employed in an advanced time-of-flight scheme for the characterization of energetic ions accelerated during laser-matter interactions. The optimization of the detector and of the advanced TOF methodology allow to obtain signals characterized by high signal-to-noise ratio and high dynamic range even in the most challenging experimental environments, where the interaction of high-intensity laser pulses with matter leads to effective ion acceleration, but also to the generation of strong Electromagnetic Pulses (EMPs) with intensities up to the MV/m order. These are known to be a serious threat for the fielded diagnostic systems. In this paper we report on the measurement performed with the PW-class laser system Vega 3 at CLPU (∼30 J energy, ∼1021 W/cm2 intensity, ∼30 fs pulses) irradiating solid targets, where both tens of MeV ions and intense EMP fields were generated. The data were analyzed to retrieve a calibrated proton spectrum and in particular we focus on the analysis of the most energetic portion (E > 5.8 MeV) of the spectrum showing a procedure to deal with the intrinsic lower sensitivity of the detector in the mentioned spectral-range.

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