APOLLON laser facility was initiated by Nobel Laureat Gérard Mourou to become one of the few European 10 PW laser facilities. End of 2018, APOLLON reached 1 PW peak power. Experiments at this power are under preparation with an expected start during spring 2019 or early summer. In parallel, today the laser is under upgrade for reaching 10 PW in few years with an intermediate step at around 5 PW dedicated to the development of experiments at this high power. APOLLON will be open for external users on 2020 at 1 PW and very likely on 2021 at several PW.
APOLLON has two experimental areas on which X-ray sources will be developed. The so-called "Long focal length area" (LFA) is dedicated to electron acceleration and related X-ray emission. The room may accommodate focal length up to 9m. The experiments are designed in a way to allows single or double stage electron acceleration with expected electron energies reaching several 10's of GeV. X-ray emission from betatron will be used as a diagnostic of electron acceleration processes but will be also developed independently aiming at achieving energetic and well-collimated X-ray beam. The experiment has been set in a way to allows heads-on electron-laser collision for Compton scattering experiments.
The second target area called "Short Focal area", aims at achieving intensities as high as possible for electron and ion acceleration, non-linear QED tests and X-ray generation through high harmonic generation on solid. X-ray emission ranging up to 10 keV is foreseen, with very high peak power at lower energy.
We report spatial and spectral characterization an optical-field-ionized high-order harmonic-seeded soft-x-ray laser. We
show that it can be controlled between a regular Gaussian shape and a Bessel profile exhibiting several rings via the IR
laser pump intensity. The temporal coherence and spectral linewidth of both the seeded and unseeded soft-x-ray lasers
were experimentally measured using a varying path difference interferometer. It showed that the high-order harmonic is
subject to a strong spectral narrowing during its propagation in the plasma amplifier without rebroadening at saturation.
Also, we present a new method to generate ultra-short x-ray laser pulses by using the laser-driven betatron source to
photo-pump inner-shell transitions.
In this paper we present the perspectives of the development of the XUV laser sources using High-power laser facilities.
We focus our paper on the present statuts of the LASERIX facility and especially its role in the development of the XUV
laser sources considering the French "Institut de la Lumière Extrême" (ILE) and the potential European project Extreme
Light Infrastructure (ELI).
We present the longitudinal coherence measurement of the transient inversion collisional x-ray laser for the first time. The Ni-like Pd x-ray laser at 14.68 nm is generated by the LLNL COMET laser facility and is operating in the gain-saturated regime. Interference fringes are produced using a Michelson interferometer setup in which a thin multilayer-coated membrane is used as a beam splitter. The longitudinal coherence length for the picosecond duration 4<i>d</i><sup>1</sup><i>S</i><sub>0</sub> -> 4<i>p</i><sup>1</sup><i>P</i><sub>1</sub> lasing transition is determined to be ~400 µm (1/e HW) by adjusting the length of one interferometer arm and measuring the resultant variation in fringe visibility. This is four times improved coherence than previous measurements on quasi-steady state schemes largely as a result of the narrower line profile in the lower temperature plasma. The inferred gain-narrowed linewidth of ~0.29 pm is also substantially narrower than previous measurements on quasi-steady state x-ray laser schemes. This study shows that the coherence of the x-ray laser beam can be improved by changing the laser pumping conditions. The x-ray laser is operating at 4 - 5 times the transform-limited pulse.
Metrology of XUV beams and more specifically X-ray laser (XRL) beam is of crucial importance for development of applications. We have then developed several new optical systems enabling to measure the x-ray laser optical properties. By use of a Michelson interferometer working as a Fourier-Transform spectrometer, the line shapes of different x-ray lasers have been measured with an unprecedented accuracy (δλ/λ~10<sup>-6</sup>). Achievement of the first XUV wavefront sensor has enable to measure the beam quality of laser-pumped as well as discharge pumped x-ray lasers. Capillary discharge XRL has demonstrated a very good wavefront allowing to achieve intensity as high 3*10<sup>14</sup> Wcm<sup>-2 </sup>by focusing with a f = 5 cm mirror. The measured sensor accuracy is as good as λ/120 at 13 nm. Commercial developments are under way.
The objective of Target Physics Program at CEA is the achievement of ignition on the LMJ, a glass laser facility of 1.8 MJ which will be competed by 2008. They include theoretical work, experimental work and numerical simulations. An important part of experimental studies is made in collaboration with US DOE Laboratories: Lawrence Livermore National Laboratory, Los Alamos National Laboratory and the Laboratory for Laser Energetics at the University of Rochester. Experiments were performed on Phebus, NOVA and OMEGA; they included diagnostics developments. Recent efforts have been focused on Laser Plasma Interactions, hohlraum energetics, symmetry, ablator physics and hydrodynamic instabilities. Ongoing work prepare the first experiments on the LIL which is a prototype facility of the LMJ. They will be performed by 2002. Recent progress in ICF target physics allows us to precise laser specifications to achieve ignition with reasonable margin.
Recent experiments, performed at the C.E.A./Limeil-Valenton P102 laser facility on the Ni-like transient collisional scheme, are reported in this paper. They mainly aimed at enhancing the efficiency and improving the optical properties of the already demonstrated 4d J equals 0/4p J equals 1 Ag<SUP>19+</SUP> x-ray laser at 13.9 nm. The now classical 2- stage traveling-wave irradiation of slab targets was used, the illumination sequence being constituted of a long (600 ps) low-flux (0.5 - 11 J) laser pulse followed (200 ps later) by a short (< 1 ps) high intensity (1 - 20 J) one. The work novelty was the use of frequency-doubled pulses, either for the pre-forming or the pumping one. Various combinations ((omega) -(omega) , 2(omega) -(omega) , (omega) - 2(omega) ) have been investigated in terms of lasing performances. High gains, around 34/cm, have been measured and saturation achieved for target lengths above 4 mm. A strong enhancement, up to a few (mu) J, of the x-ray laser output has been observed, due to traveling-wave irradiation method, while the emission duration was decreased to less than 10 ps, resulting in a 300 kW source. Moreover, under specific laser conditions, a second lasing line at 16 nm was detected. Finally, the possibility of cavity operating transient collisional x-ray lasers has been demonstrated.
The aim of this paper is to identify ways in which current designs can be modified to improve the output performances of the collisional x-ray lasers. The effectiveness -- for slab systems -- of some ideas are examined from a theoretical standpoint. They all involve the temporal shaping of the driver pulse and judiciously combine low and high intensity, long and short irradiations. Simulations of Ne-like Fe and Ni- like Ag XRLs experiments are also presented to support the study.
The numerical optimization of the temporal shape of the pump laser for the design of a 38.8 angstrom H-like x-ray laser is presented. Enhancement of local and integrated gains is obtained by smoothing the pulse rise, without drastic increase of the x-ray emission duration. Sensitivity of the results to the pulse intensity is also examined. High temporal resolution spectroscopy of aluminum targets performed in the keV range at the P102 facility in Limeil is finally presented.
Soft x-ray lasers laboratory devices are now reliable enough that their high brightness and significant coherence can be routinely exploited. This paper will describe some potential uses of such systems to probe, through interferometry diagnostic techniques, large high density plasmas relevant to Inertial Confinement Fusion.
An experimental evidence is now emerging: high gain coefficients and brightnesses can be easily obtained along the Ne-like (1s<SUP>2</SUP>2s<SUP>2</SUP>2p<SUP>5</SUP>)3p <SUP>1</SUP>S<SUB>0</SUB> yield 3s <SUP>3</SUP>P<SUB>1</SUB> (historically anomalous) lasing line, in intermediate-Z [(Ti) 22 less than or equal to Z less than or equal to 34 (Se)] plasmas, using low intensity prepulse techniques. An attempted theoretical explanation of the exact prepulse role in the amplification mechanism is reported, based on recent simulations of a European campaign conducted at the LULI (France) facility.
Ne-like Se X-ray laser experiments have been performed to examine the effects in line focus width narrowing on amplification in a collisional excitation scheme. Variation from 40 micrometers up to 180 micrometers has been investigated. Significant changes in temperature and ionization balance have been observed and explained from theoretical considerations.