The SEPAGE spectrometer (Spectromètre Electrons Protons A Grandes Energies) was realized within the PETAL+ project funded by the French ANR (French National Agency for Research). This plasma diagnostic, installed on the LMJ-PETAL laser facility, is dedicated to the measurement of charged particle energy spectra generated by experiments using PETAL (PETawatt Aquitaine Laser). SEPAGE is inserted inside the 10-meter diameter LMJ experimental chamber with a SID (Diagnostic Insertion System) in order to be close enough to the target. It is composed of two Thomson Parabola measuring ion spectra and more particularly proton spectra ranging from 0.1 to 20 MeV and from 8 to 200 MeV for the low and high energy channels respectively. The electron spectrum is also measured with an energy range between 0.1 and 150 MeV. The front part of the diagnostic carries a film stack that can be placed as close as 100 mm from the target center chamber. This stack allows a spatial and spectral characterization of the entire proton beam. It can also be used to realize proton radiographies.
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 MégaJoule (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.
Streak cameras and framing cameras used for studying single shot laser created plasmas at LIL and soon at LMJ need to be regularly controlled to assure a good operating system. This poster presents the laboratories that have been set up at CEA-CESTA to overcome this task. To cover the entire spectral domain required, many sources have been designed. First, AZUR laboratory is supposed to deliver three measurements ways equipped with laser sources for static and dynamic visible detectors control. Second, CADENCE laboratory is ought to test temporal resolution in UV domain by delivering laser ps pulse train. X-ray cameras are then calibrated by replacing CsI photocathodes with Pd photocathodes sensitive in UV. Finally, STATIX laboratory aims at controlling X-ray streak and framing cameras in static regime with several continuous X-ray sources. Properties as linearity, homogeneity, sensitivity and temporal response are going to be measured to guaranty diagnostics performances on LIL plasma physics shots.
Rare gas cluster jets are an intermediate medium between solid and gas targets. Laser-cluster jets interaction may generate a great number of energetic particles such as X-rays, UV, high harmonics, ions, electrons and neutrons. To understand all the mechanisms involved in this interaction we need to make a complete study of individual cluster response to an ultra-short laser pulse. We studied the laser interaction with our Argon cluster gas jet, which is well characterized in cluster size and density, to enlarge the knowledge of this interaction. We measured absorption, heating and X-ray emission spectra versus laser parameters and clusters size (~15-30 nm). We show that there is a strong refraction effect on laser propagation due to the residual gas density. This effect was confirmed by laser propagation simulation with a cylindrical 2D particle code WAKE. The role played by refraction was to limit maximum laser intensity on the focal spot and to increase interaction volume. By this way, X-ray emission was observed with laser intensity not so far from the ionization threshold (few 1014 W.cm-2). We also studied plasma expansion both at cluster scale and focal volume scale and deduced the deposited energy distribution as a function of time. Thanks to a simple hydrodynamic model, we used these results to study cluster expansion. X-ray emission is then simulated by TRANSPEC code in order to reproduce X-ray spectra and duration. Those results revealed an extremely brief X-ray emission consistent with a preliminary measure by streak camera (~ps).