Publications

2017

• Kinetic and finite ion mass effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
  
  • Siminos E.
  • Grech M.
  • Wettervik B. Svedung
  • Fülöp T.
  New Journal of Physics, Institute of Physics: Open Access Journals, 2017, 19. We study kinetic effects responsible for the transition to relativistic self-induced transparency in the interaction of a circularly-polarized laser-pulse with an overdense plasma and their relation to hole-boring (HB) and ion acceleration. It is demonstrated using particle-in-cell simulations and an analysis of separatrices in single-electron phase-space, that ion motion can suppress fast electron escape to the vacuum, which would otherwise lead to transition to the relativistic transparency regime. A simple analytical estimate shows that for large laser pulse amplitude a 0 the time scale over which ion motion becomes important is much shorter than usually anticipated. As a result of enhanced ion mobility, the threshold density above which HB occurs decreases with the charge-to-mass ratio. Moreover, the transition threshold is seen to depend on the laser temporal profile, due to the effect that the latter has on electron heating. Finally, we report a new regime in which a transition from relativistic transparency to HB occurs dynamically during the course of the interaction. It is shown that, for a fixed laser intensity, this dynamic transition regime allows optimal ion acceleration in terms of both energy and energy spread. (10.1088/1367-2630/aa8e66)
  DOI : 10.1088/1367-2630/aa8e66
• Experimental observation of a current-driven instability in a neutral electron-positron beam
  
  • Warwick J.
  • Dzelzainis T.
  • Dieckmann M.E.
  • Schumaker W.
  • Doria D.
  • Romagnani L.
  • Alejo A.
  • Poder K.
  • Cole J.M.
  • Yeung M.
  • Krushelnick K.
  • Mangles S.P.D.
  • Najmudin Z.
  • Reville B.
  • Samarin G.M.
  • Symes D.D.
  • Thomas A.G.R.
  • Borghesi M.
  • Sarri G.
  Physical Review Letters, American Physical Society, 2017, 119 (18), pp.185002. We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (≥1 T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of εB≈10-3 is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets. (10.1103/PhysRevLett.119.185002)
  DOI : 10.1103/PhysRevLett.119.185002
• Targets for high repetition rate laser facilities: needs, challenges and perspectives
  
  • Prencipe I.
  • Fuchs J.
  • Pascarelli S.
  • Schumacher D.
  • Stephens R.
  • Alexander N.
  • Briggs R.
  • Büscher M.
  • Cernaianu M.
  • Choukourov A.
  • de Marco M.
  • Erbe A.
  • Fassbender J.
  • Fiquet Guillaume
  • Fitzsimmons P.
  • Gheorghiu C.
  • Hund J.
  • Huang L. G.
  • Harmand M.
  • Hartley J.
  • Irman A.
  • Kluge T.
  • Konopkova Z.
  • Kraft S.
  • Kraus D.
  • Leca V.
  • Margarone D.
  • Metzkes J.
  • Nagai K.
  • Nazarov W.
  • Lutoslawski P.
  • Papp D.
  • Passoni M.
  • Pelka A.
  • Perin J.
  • Schulz J.
  • Smid M.
  • Spindloe C.
  • Steinke S.
  • Torchio R.
  • Vass C.
  • Wiste T.
  • Zaffino R.
  • Zeil K.
  • Tschentscher T.
  • Schramm U.
  • Cowan T.
  High Power Laser Science and Engineering, Cambridge University Press, 2017, 5. A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities. (10.1017/hpl.2017.18)
  DOI : 10.1017/hpl.2017.18
• Highly scalable femtosecond coherent beam combining demonstrated with 19 fibers
  
  • Le Dortz J.
  • Heilmann A.
  • Antier M.
  • Bourderionnet J.
  • Larat C.
  • Fsaifes I.
  • Daniault L.
  • Bellanger S.
  • Simon Boisson C.
  • Chanteloup Jean-Christophe
  • Lallier E.
  • Brignon A.
  Optics Letters, Optical Society of America - OSA Publishing, 2017, 42 (10), pp.1887. (10.1364/OL.42.001887)
  DOI : 10.1364/OL.42.001887
• XUV and x-ray elastic scattering of attosecond electromagnetic pulses on atoms
  
  • Rosmej F.
  • Astapenko V. A.
  • Lisitsa V S
  Journal of Physics B: Atomic, Molecular and Optical Physics, IOP Publishing, 2017, 50 (23). Elastic scattering of electromagnetic pulses on atoms in XUV and soft X-ray ranges is considered for ultra-short pulses. The inclusion of the retardation term, non-dipole interaction and an efficient scattering tensor approximation allowed studying the scattering probability in dependence of the pulse duration for different carrier frequencies. Numerical calculations carried out for Mg, Al and Fe atoms demonstrate that the scattering probability is a highly non-linear function of the pulse duration and has extrema for pulse carrier frequencies in the vicinity of the resonance-like features of the polarization charge spectrum. Closed expressions for the non-dipole correction and the angular dependence of the scattered radiation are obtained. (10.1088/1361-6455/aa90cf)
  DOI : 10.1088/1361-6455/aa90cf
• 43rd European Physical Society Conference on Plasma Physics
  
  • Mantica Paola
  • Dendy Richard
  • Jacquemot Sylvie
  Plasma Physics and Controlled Fusion, IOP Publishing, 2017, 59 (1), pp.010101. (10.1088/0741-3335/59/1/010101)
  DOI : 10.1088/0741-3335/59/1/010101
• High-contrast 10 fs OPCPA-based front end for multi-PW laser chains
  
  • Papadopoulos D.
  • Ramirez P.
  • Genevrier K.
  • Ranc L.
  • Lebas N.
  • Pellegrina A.
  • Le Blanc Catherine
  • Monot P.
  • Martin L.
  • Zou J.
  • Mathieu F.
  • Audebert P.
  • Georges Patrick
  • Druon F.
  Optics Letters, Optical Society of America - OSA Publishing, 2017, 42 (18), pp.3530. Applications using multi-PW lasers necessitate high temporal pulse quality with a tremendous contrast ratio (CR). The first crucial prerequisite to achieve multi-PW peak power is the generation of ultrashort pulses with good spectral phase quality. Second, to avoid any deleterious pre-ionization effect on targets, nanosecond contrast better than 10$^{12}$ is also targeted. In the framework of the Apollon 10 PW French laser program, we present a high-contrast 10 fs front-end design study to inject highly energetic Ti:sapphire PW lasers. The CR has been measured and analyzed in different time ranges highlighting the different major contributions for each scale. (10.1364/OL.42.003530)
  DOI : 10.1364/OL.42.003530
• Full PIC simulations of solar radio emission
  
  • Sgattoni A.
  • Henri P.
  • Briand C.
  • Amiranoff F.
  • Riconda C.
  , 2017, 2017. Solar radio emissions are electromagnetic (EM) waves emitted in the solar wind plasma as a consequence of electron beams accelerated during solar flares or interplanetary shocks such as ICMEs. To describe their origin, a multi-stage model has been proposed in the 60s which considers a succession of non-linear three-wave interaction processes. A good understanding of the process would allow to infer the kinetic energy transfered from the electron beam to EM waves, so that the radio waves recorded by spacecraft can be used as a diagnostic for the electron beam.Even if the electrostatic problem has been extensively studied, full electromagnetic simulations were attempted only recently. Our large scale 2D-3V electromagnetic PIC simulations allow to identify the generation of both electrostatic and EM waves originated by the succession of plasma instabilities. We tested several configurations varying the electron beam density and velocity considering a background plasma of uniform density. For all the tested configurations approximately 105 of the electron-beam kinetic energy is transfered into EM waves emitted in all direction nearly isotropically. With this work we aim to design experiments of laboratory astrophysics to reproduce the electromagnetic emission process and test its efficiency.
• Electron Weibel instability in relativistic counterstreaming plasmas with flow-aligned external magnetic fields
  
  • Grassi A.
  • Grech M.
  • Amiranoff François
  • Pegoraro F.
  • Macchi A.
  • Riconda C.
  Physical Review E, American Physical Society (APS), 2017, 95 (2), pp.023203. The Weibel instability driven by two symmetric counterstreaming relativistic electron plasmas, also referred to as current-filamentation instability, is studied in a constant and uniform external magnetic field aligned with the plasma flows. Both the linear and nonlinear stages of the instability are investigated using analytical modeling and particle-in-cell simulations. While previous studies have already described the stabilizing effect of the magnetic field, we show here that the saturation stage is only weakly affected. The different mechanisms responsible for the saturation are discussed in detail in the relativistic cold fluid framework considering a single unstable mode. The application of an external field leads to a slight increase of the saturation level for large wavelengths, while it does not affect the small wavelengths. Multimode and temperature effects are then investigated. While at high temperature the saturation level is independent of the external magnetic field, at low but finite temperature the competition between different modes in the presence of an external magnetic field leads to a saturation level lower with respect to the unmagnetized case. (10.1103/PhysRevE.95.023203)
  DOI : 10.1103/PhysRevE.95.023203
• Laser impulse coupling measurements at 400 fs and 80 ps using the LULI facility at 1057 nm wavelength
  
  • Phipps Claude R.
  • Boustié Michel
  • Chevalier Jean Marc
  • Baton Sophie D.
  • Brambrink Erik
  • Berthe Laurent
  • Schneider Matthieu
  • Videau Laurent
  • Boyer Séverine A.E.
  • Scharring Stefan
  Journal of Applied Physics, American Institute of Physics, 2017, 122, pp.Article number 193103. At the École Polytechnique « LULI » facility, we have measured the impulse coupling coefficient Cm (target momentum per joule of incident laser light) with several target materials in vacuum, at 1057 nm and 400 fs and 80 ps pulse duration. A total of 64 laser shots were completed in a two-week experimental campaign, divided between the two pulse durations and among the materials. Our main purpose was to resolve wide discrepancies among reported values for Cm in the 100 ps region, where many applications exist. A secondary purpose was to compare Cm at 400 fs and 80 ps pulse duration. The 80 ps pulse was obtained by partial compression. Materials were Al, Ta, W, Au, and POM (polyoxymethylene, trade name Delrin). One application of these results is to pulsed laser ablation propulsion in space, including space debris re-entry, where narrow ranges in Cm and specific impulse Isp spell the difference between dramatic and uneconomical performance. We had difficulty measuring mass loss from single shots. Imparted momentum in single laser shots was determined using pendulum deflection and photonic Doppler velocimetry. Cm was smaller at the 400 fs pulse duration than at 80 ps. To our surprise, Cm for Al at 80 ps was at most 30 N/MW with 30 kJ/m2 incident fluence. On the other extreme, polyoxymethylene (POM, trade name Delrin) demonstrated 770 N/MW under these conditions. Together, these results offer the possibility of designing a Cm value suited to an application, by mixing the materials appropriately. (10.1063/1.4997196)
  DOI : 10.1063/1.4997196
• Polarization Dependence of Bulk Ion Acceleration from Ultrathin Foils Irradiated by High-Intensity Ultrashort Laser Pulses
  
  • Scullion C.
  • Doria D.
  • Romagnani L.
  • Sgattoni A.
  • Naughton K.
  • Symes D.R.
  • Mckenna P.
  • Macchi A.
  • Zepf M.
  • Kar S.
  • Borghesi M.
  Physical Review Letters, American Physical Society, 2017, 119 (5), pp.054801. The acceleration of ions from ultrathin (10–100 nm) carbon foils has been investigated using intense (∼6×1020 W cm-2) ultrashort (45 fs) laser pulses, highlighting a strong dependence of the ion beam parameters on the laser polarization, with circularly polarized (CP) pulses producing the highest energies for both protons and carbons (25−30 MeV/nucleon); in particular, carbon ion energies obtained employing CP pulses were significantly higher (∼2.5 times) than for irradiations employing linearly polarized pulses. Particle-in-cell simulations indicate that radiation pressure acceleration becomes the dominant mechanism for the thinnest targets and CP pulses. (10.1103/PhysRevLett.119.054801)
  DOI : 10.1103/PhysRevLett.119.054801