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Since the first experimental campaign conducted in 2014 with mid field Gated X-ray Imager (GXI) and two quadruplets (20 kJ at 351 nm) focused on target, the Laser MegaJoule (LMJ) operational capability is still growing up. New plasma diagnostics have been implemented: a large field 2D GXI, two broadband x-ray spectrometers (called DMX and miniDMX), a specific soft x-ray spectrometer and a Laser Entrance Hole (LEH) imaging diagnostic. A series of experiments have been performed leading to more than 60 shots on target. We will present the plasma diagnostics development status conducted at CEA for experimental purpose. Several diagnostics are now under manufacturing or development which include a Streaked Soft X-ray Imager (SSXI), an Equation Of State (EOS) diagnostic suite (“EOS pack”), a Full Aperture BackScattering (FABS) diagnostic, a Near Backscattered Imager (NBI), a high resolution 2D GXI, a high resolution x-ray spectrometer, a specific set of two polar hard x-ray imagers for LEH characterization and a set of Neutron Time of Flight (NTOF) detectors. We describe here the diagnostics design and performances in terms of spatial, temporal and spectral resolutions. Their designs have taken into account the harsh environment (neutron yields, gamma rays, electromagnetic perturbations, debris and shrapnel) and the safety requirements.

We present new progress in the optimization and understanding of the transient collisional pumping scheme using an ultra-short sub-ps heating pulse. The effect of traveling-wave irradiation in enhancing the lasing output of the 4d-4p Ni-like Ag line is studied in detail. A new irradiation scheme using a frequency-doubled 600 ps pulse to preform a plasma is tested. Strong lasing is also obtained on a new line at 16.05 nm that we identify to a 4f-4d transition in Ni-like Ag. Finally we review our recent work in the development of applications of the 21.2 nm zinc laser for imaging or exciting matter. New experiments include the probing of a plasma by imaging Fresnel interferometry and a first attempts to demonstrate two-photon ionization in a xenon gas.

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 19+ 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 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.

We present and discuss time resolved spectra (KeV range) of solid density plasmas produced by the interaction of clean high intensity laser pulses (400 fs, 0.53 im light) with solid and foil targets at intensities between 1018 W/cm2 and 1020 W/cm2. Results have been obtained with the new PX1 x-ray streak camera which hasa temporal resolution of 750 fs in the KeV x-ray range.Keywords: X-ray Spectroscopy, Femtosecond temporal resolution, High density plasmas, Ultrashort laser producedplasmas. 1. INTRODUCTION Over the past seven years, a revolution has occurred in our ability to produce extremely compact, highaverage power and high intensity lasers. These recent progresses are the direct results of the use of both a newamplification technique, namely the technique of Chirped Pulse Amplification (CPA)[1}, and new broadbandamplification media such as Ti:sapphire and Cr:LiSAF[2]. Laser pulse lengths are now compressed down todurations of less than 100 femtosecond. Although the laser energy is not so high, large intensity can be achieved dueto extremely short pulse duration and very good focusability. Furthermore extremely high repetition rates are nowcurrently achieved[3}. These advances have made possible the production and the study ofhot solid density plasmaswhich are unique sources of ultrafast x-ray pulses[4,5]. These short pulses of x-rays could be a very useful tool to

The use of different shifted narrow band amplifying media in the chirped pulse amplification technique allows us to produce sub-100 TW pulses with duration in the 250 - 300 fs range. By focusing these pulses on target we have obtained peak intensities above 2.1019 W/cm2.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The chirped pulse amplification technique combined with the use of different shifted narrow band amplifying media allows us to produce sub-100 TW pulses with duration in the 250 - 300 fs range. By focusing these pulses on target we have obtained peak intensities above 2.1019 W/cm2 with a contrast ratio of 10-7 - 10-6 for the nanosecond background.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.