The French Commissariat a l'Energie Atomique (CEA) began the construction of the Laser Megajoule (LMJ), a 240-beam laser facility, at the CEA laboratory CESTA near Bordeaux. The LMJ will be a cornerstone of the CEA "Programme Simulation", the French analog to the US Stockpile Stewardship Program. The LMJ is designed to deliver 2MJ of 0.35 μm light to targets for high energy density physics experiments and to ultimately obtain ignition and propagating burn with DT targets in the laboratory. The Scientific conception and system design was completed in 1999 and was followed by the Demonstration of an Engineering Prototype which was achieved in early 2003 with operation of one beam of the Ligne d'Integration Laser (LIL) at CESTA, with 9.5 kJ of UV light (0.35 μm) in less than 9 ns from a single laser beam. The Ralization phase of the LMJ facility was initiated in March of 2003 with the construction start of teh building and the target chamber. This paper will present results from the commissioning phase of the LIL program in 2003 and 2004. The activation and commissioning of the full 8 beamlines of LIL over the next 2 years will be part of determining the final specifications and integration and commissioning plans for the LMJ which is expected to demonstrate first light performance through 240 beams by 2010.

The French Commissariat a l'Energie Atomiqe (CEA) began the construction of the Laser Megajoule (LMJ), a 240 beams laser facility, at the CEA Laboratory CESTA near Bordeaux. The LMJ will be a cornerstone of the CEA "Programme Simulation", similar to LLNL "NIF" facility.The LMJ is designed to deliver 2 MJ of 0.35 mu m light to targets for high energy density physics experiments and to ultimately obtain ignition and propagating burn with DT targets in the laboratory.The scientific conception and system design was completed in 1999 and was followed by the Demonstration of an Engineering Prototype which was achieved in early 2003 with operation of one beam of the Ligne d'Integration Laser (LIL) at CESTA, with 9.5 U of UV light (0.35 mu m) in less than 9 ns from a single laser beam.The construction phase of the LMJ facility was initiated in March 2003 with the start of work on the building and the target chamber.This paper will present a summary of 2004 LIL results and a description of LMJ, which is expected to demonstrate first light performance through 240 beams by 2009. (c) 2005 Elsevier B.V. All rights reserved.

The French Commissariat à l'Energie Atomique (CEA) began the construction of the Laser Megajoule (LMJ), a 240-beam laser facility, at the CEA Laboratory CESTA near Bordeaux. The LMJ will be a cornerstone of the CEA ‘Programme Simulation’, the French analog of the US Stockpile Stewardship Program. The LMJ is designed to deliver 2 MJ of 0.35 µm light to targets for high energy density physics experiments and to ultimately obtain ignition and propagating burn with DT targets in the laboratory. The Scientific conception and system design was completed in 1999 and was followed by the Demonstration of an Engineering Prototype which was achieved in early 2003 with the operation of one beam of the Ligne d'Intégration Laser (LIL) at CESTA, with 9.5 kJ of UV light (0.35 µm) in less than 9 ns from a single laser beam. The realization phase of the LMJ facility was initiated in March of 2003 with the start of construction of the building and the target chamber. This paper will present results from the commissioning phase of the LIL program in 2003 and 2004. The activation and commissioning of all eight beamlines of LIL over the next 2 years will be part of determining the final specifications and integration and commissioning plans for the LMJ, which is expected to demonstrate first light performance through 240 beams by 2009.

The LIL which is under construction at the French Atomic Energy Commission CESTA center is an 8 beam facility - 60 kJ @ 0.35 mum - dedicated to laser matter interaction experiments. This facility is now in the last construction phase and the first experiments have already been conducted in order to demonstrate the performances of both front end and multipath high energy section at 1.05 mum. The experiments that were recently conducted have demonstrated the efficiency of the 4 pass and L-tum amplification concept, and already show that the expected output intensity performance at 1w has been reached. Moreover, these experiments have confirmed the capability of our laser simulation code (Miro) to predict this laser output performance. We are currently implementing the 1w / 3w conversion and focusing system, which combines for each beam a large lw grating associated with KDP/DKDP frequency doubler and tripler and a large 3w (0.35 mum) focusing grating. Focal spot size will be available in the circle divide 0.5 to 4 mm range with either a circular or elliptical spatial profile. LIL will also support the beam smoothing capability (longitudinal or transverse). The 1w section is currently under tests at the kJ level, and 3w tests will be performed very soon. The LIL prototype facility is the first step of the French Atomic Energy Commission program toward the construction of the 240 beam Laser Megajoule (LMJ) facility which will enable us to conduct high energy density experimental program in the 640 TW @ 2 MJ range before the end of this decade.

The construction of the Laser Megajoule is scheduled for the end of 2008. A first step is the construction of a prototype named LIL for "Ligne d'Integration Laser" which consists of a complete laser bundle of 8 beamlets. The LIL facility, completed at the beginning of 2002, will be equipped with a target chamber in order to qualify the beam quality and performances on a target and to start laser-plasma experiments at the beginning of 2003. The LIL building, is completed and the installation of laser components started in 2000. In order to meet the project schedule, the construction of the LMJ building now under design will take place at the end of 2002.

AIRIX is an induction linear accelerator which will be used for flash radiography in Commissariat A L'Energie Atomique In France. Designed to produce an X-ray dose of some hundreds Rads at 1 meter with an X-ray focal spot size diameter of less than 2 mm (LANL-CEA DAM definition), this facility consists in a 3,8 MeV/2 kA pulsed electron injector and 15,4 MeV induction accelerator powered by 32 high voltage generators. A prototype of this accelerator, called PIVAIR, has been studied and realized in CEA CESTA near Bordeaux. PIVAIR is a validation step for AIRIX at 8 MeV. It includes an injector (3,6 MeV, 3,2 kA, 60 ns) and 16 induction cells supplied by 8 high voltage generators (250 kV, 70 ns). Two different technologies of induction cells have been tested (Rexolite insulator or ferrite Under Vacuum). We have chosen ferrite under vacuum cells technology after comparison of results on beam transport and reliability tests. A focusing experiment at 7.2 MeV of the electron beam has been achieved during summer 1997. We have begun to produce X-rays in October 1997. A dose level of 50 Rad at 1 meter has been achieved with an X-ray spot size diameter of 3.5 to 4 mm (LANL-CEA DAM definition). Static flash radiography of very dense object have been achieved from November 1997 until February 1998. We have been able to test in situ new kinds of very high sensitive X-ray detectors and to check they had reached our very ambitious goals: quantum efficiency at 5 MeV > 50% instead of 1% for luminous screens and film, sensitivity < 10 (mu) Rad (100 time more sensitive than radiographic luminous screens and films), dynamic range > 100, resolution < 2 mm. The AIRIX accelerator has been built in the CEA-MORONVILLIERS test site near Reims under an industrial collaboration with the THOMSON- CSF Company. It is housed in a reinforced concrete bunker and has an overall length of 60 meters. The 20 MeV electron beam has been focused on a 1 mm thick Tantalum target to produce an X-ray fluence of more than 300 Rads at one meter from the target. The result is a single radiograph of the device explosion under test with the high stopping power detector located in a blast protection set behind the device. In this communication we will present all these techniques which correspond to a significant effort of CEA begun in 1992. AIRIX facility will be available to run detonics experiments before end of 2000.

AIRIX is an induction linear accelerator which will be used for flash radiography in CEA/DAM.Designed to produce an X-ray dose of more than 500 Rads at 1 meter with an X-ray focal spot size diameter of less than 2 mm (LANL-CEA DAM definition), this facility consists in a 4 MeV/3.5 kA pulsed electron injector and 16 MeV induction accelerator powered by 32 high voltage generators.A prototype of this accelerator, called PIVAIR, has been studied and realized in CEA CESTA near Bordeaux. PIVAIR is a validation step for AIRIX at 8 MeV. It includes an injector (4 MeV, 3.5 kA, 60 ns) and 16 inductor cells supplied by 8 high voltage generators (250 kV, 70 ns). Two different technologies of induction cells have been tested (rexolite insulator or ferrite under vacuum).We have chosen ferrite under vacuum cells technology after comparison of results on beam transport and reliability tests. A focusing experiment at 7.2 MeV of the electron beam as been achieved during summer 1997. We have begun to produce X-rays in October 1997. A dose level of 50 Rad at 1 meter has been achieved with an X-ray spot size diameter of 3.5 to 4 mm (LANL-CEA DAM definition).Static flash radiography of very dense object have been achieved from November 97 until February 98. We have been able to test in situ new kinds of very high sensitive X-ray detectors and to check they had reached our very ambitious goals:quantum efficiency at 5 MeV > 50% instead of 1% for luminous screens and filmsensitivity < 10 mu Rad (100 time more sensitive than radiographic luminous screens and films)dynamic range > 100resolution <2 mmWe will present in this communication brand new kinds of detection systems, called high stopping power detectors, such as:gamma camera with segmented thick crystal of EGO and MCP image intensifiermultistep parallel plate avalanche chamberpixellized CdTe MeV photoconductor matrixAIRIX accelerator is being built by THOMSON CSF Company in CEA Moronvilliers near Reims.It is housed in a reinforced concrete bunker and has an overall length of 60 meters. The 20 MeV electron beam will be focused on a 1.5 mm thick Tantalum target to produce an X-ray fluence (flux) of more than 500 Rads one meter from the target. The result is a single radiograph of the device explosion under test with the high stopping power detector located in a blast protection set behind the device.In this communication we will present all these technics which correspond to a significant effort of CEA begun in 1992.AIRIX facility will be available to run detonics experiments before end of 2000.

We present an x-ray detector with a high sensitivity in the 1–20 MeV x-ray range. This device consists of a scintillator coupled with a microchannel plate image intensifier tube working in the visible range. The performance of the hard-x-ray detector is described. The modulation transfer function, the characteristic curve, and the detection threshold were measured. Using an x-ray flash generator in the 4 MeV x-ray range, we have been able to record images of dense spheres for dose levels as low as 1.5 μGray. Similar experiments have been realized with a linear accelerator for different x-ray spectra (10 and 20 MeV). Our results demonstrate that this device works in a range where the most sensitive intensifying screens and films, usually used on flash radiography, are inoperative.

Dealing with dynamic behavior of solids, flows, detonator initiation, high explosives properties, shock waves and other fast processes, implies a large amount of metrology problems. When studies on shock waves began, forty five years ago, only flash X-ray radiography achieving chronometric measurements was developed, in order to investigate shaped charges jets. This technique has also been widely used in detonics because it does not affect hydrodymanic phenomena. Since that time, a large amount of data has been gathered and has allowed physicists to confirm many theories. Later pulsed high energy radiographic machines emitting X-rays have allowed large images record of voluminous objects containing dense materials (with high atomic numbers) and therefore very absorbing. Our laboratory has been working in this field for more than 30 years. A great deal of effort has been spent to enhance the radiographic capabilities of our X-ray machines. High dose levels and better spot size diameter of X-ray sources have allowed quite good records for a better understanding on material densities and boundaries. During the same period of time many works were led on the detection of low X-ray fluences. We present in this communication the main studies developed in that field on cells of light screens coupled with visible film and on microchannel plates image intensifiers.

Dealing with dynamic behavior of solids, flows, detonator initiation, high explosive properties, shock waves, and other fast processes involves many metrology problems. In this communication, we classify various techniques according to the kinematic or thermodynamic parameters that we need to improve our knowledge of detonics problems. They are primarily: spacial observation of the phenomena versus time, chronometry of events, material densities, and boundaries detection by radiography.

The dynamic behavjour of the PVF2 gauge designed and produced by CEV-M* has been investigated both by CEV-M* and CEG** under plane wave loading. In the range 0-100 kbar, the accuracy on the measured stress is ± 5% and the gauge can be used for both compression and release. In the 100 - 280 kbar range, the gauge can only be used in compression and the uncertainty increases from ± 5% to ± 30%. At approximately 280 kbar, the calibration curve shows a discontinuity and above 280 kbar the sensitivity of the gauge decreases drastically, prohibiting the use of PVF2 as a stress sensor. In addition, we show that the electrical impedance of PVF2 drops over the range 400 to 600 kbar.

Two diagnostics for the study of hard x-ray emission produced by plasmas during inertial confinement fusion experiments, are described: (i) a hard x-ray spectrometer to measure the high-energy tail of the spectrum, with eight spectral bands in the 50–400-keV range, by fluorescence and simple filter techniques; (ii) a time-integrated pinhole imaging device using a microchannel plate converter tube and a 7.5-μm-thick tantalum photocathode adjusted for a mean spectral sensitivity around 200 keV. Adjustment and test of these diagnostics have been performed with a pulsed hard x-ray generator using a plasma focus device. Absolute calibration of the spectrometer detectors (scintillator Photomultiplier) was obtained on an x-ray tube with fluorescent emission lines (10–100 keV) and with a cobalt radioactive source at 1.23 MeV.

Dealing with dynamic behavior of solids, detonator initiation, shock and detonation waves and other fast processes implies a number of new techniques. We are working on wave propagation at velocities of several km/s, with states existing for only a few microseconds or even nanoseconds. In this case performances of our fastest rotating mirror framing cameras are not high enough to observe states of surface or large discontinuity zones (problem of dynamic blur). We have developed a new laser technique called Instantaneous Image (I.I.). This technique consists in recording a single image in a short exposure time to minimize the dynamic blur of our fast phenomena. We use a Q-switched Nd:YAG laser made of an oscillator, a pre-amplifier, a 16 mm diameter amplifier and a KDP crystal. The available energy is in the order of 200 mJ at 532 nm for a ten nanoseconds pulse duration. A large amount of work has been done to minimize the non uniformity of the delivered light, to eliminate speckle defects and to collect the most illumination light by an optimized optic device. Under these conditions a large diameter field image (D equals 200 mm) can be achieved with a resolution better than 15 line pairs/mm. With a double proximity focused microchannel plate image intensifier (M.C.P.) it is possible to obtain faster shuttered times (a few nanoseconds) with a higher gain to observe poor reflective surfaces. But under these conditions the resolution decreases drastically to some line pairs per millimeter.

We present a high gain x-ray image intensifier with high sensitivity in the 1 MeV x-ray range and a good spatial resolution developed in order to improve the radiographic detection in our experiments. In particular the gold photocathode and MCP thickness have been optimized to give the best trade off between the dose sensitivity and the spatial resolution. The large useful 60-mm-diam photocathode set on the MCP input converts the x-ray emission into electrons that are multiplied in the MCP and proximity focused onto the P11 phosphor screen deposited on a fiber-optic plate. For x-ray quanta of 1 MeV energy the x-ray image converter is more sensitive than the most sensitive x-ray screen film systems. Using for instance a pulsed x-ray source we have been able to record pictures of a sphere or of a testing metallic chart for a dose lower than 100 μrad; under these conditions the spatial resolution was greater than 1 lp mm−1 and the dynamic range was still around 10. Using an x-ray screen film under same input level we have obtained a very low dynamic range and density values actually equal to the noise level. These unique performances fulfill the requirements of a large number of detonic experiments needing a high sensitivity in the 1 MeV x-ray range.

New optical laser techniques are reviewed and classified according to the kinematic or thermodynamic parameters to improve the knowledge of detonics problems. These optic, electronic, and optoelectronic techniques include spatial observations of phenomena vs. time which are based on a framing rotating mirror or an opto-electronic camera with mirrors and optics; chronometry of events; measurements of continuous stress vs. time; velocimetry measurements of free surfaces by interferometry; the Doppler laser interferometry technique; and an instantaneous velocity field technique.

The authors present the shock compression response of a 2-mm*2-mm active area PVF2 gauge. The shock response was studied both on a phi 30-mm powder gun and with a plane wave lens of high explosives coupled to ceramic attenuators. The results obtained with 23- mu m gauges working in the 0-160-kbar range are presented. For each peak shock stress, six gauges, each coupled to two high-bandwidth transient digitizers, were used. The measurements were carried out with an accuracy of less than +or-5% below 100 kbar. The calibration curve giving the shock pressure versus the efficiency of the gauge is presented. A comparison is between polymer, manganin, and carbon gauges is given.<>

A high gain x-ray image intensifier with high sensitivity in the 1 MeV x-ray range is presented and a good spatial resolution developed in order to improve the radiographic detection in the experiments. In particular the gold photocathode and MCP thickness have been optimized to give the best trade-off between the dose sensitivity and the spatial resolution. The large useful 60 mm diameter photocathode set on the MCP input converts the x-ray emission into electrons which are multiplied in the MCP and proximity-focused onto the P11 phosphor screen deposited on a fiber optic plate. For x-ray quanta of 1 MeV energy the x-ray image converter is more sensitive than the most sensitive x-ray screen-film systems. Using, for instance, a pulsed x-ray source the authors were able to record pictures of a sphere or of a testing metallic chart for a dose lower than 100 (mu) rad; under these conditions the spatial resolution was greater than 1 lp/mm and the dynamic range was still around 10. Using an x-ray screen film under the same input level the authors have obtained a very low dynamic range and density values actually equal to the noise level. These unique performances fulfill the requirements of a large number of detonic experiments needing a high sensitivity in the 1 Mev x-ray range.

A vertical shock tube built for the study of Rayleigh‐Taylor instability induced turbulent mixing is described. The first results obtained by schlieren visualization concern the interaction between a Mach 1.45 shock wave and subsequent reflected waves and a 1.7 cm wide diffusive SF6‐air mixing zone. The mixing zone behavior is compared to the evolutions obtained in other analogous experiments with the help of a turbulence model in a one‐dimensional code.