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Laser megajoule (LMJ) is a laser facility being built by the French nuclear science directorate, Commissariat a l'Energie Atomique. This facility is a large flashlamp pumped laser (1.8-MJ optical output). The pulsed power conditioning system of LMJ is based on a modular design of 480 modules (400-MJ energy capacitor bank). A new capacitor bank module (CBM) for the LMJ power conditioning system has been developed by the Institute of High Current Electronics (IHCE, Tomsk) in collaboration with International Technologies for High Pulsed Power (France). Two such modules were produced and tested in IHCE. The main parts of the CBM are the following: high-voltage power supplies, command control system, air conditioning system, capacitor block, and cables delivering the energy to a load. The parameters of the module are the following: total rated capacitance of 2900 (+4%) muF, charging voltage up to 24 kV, peak current amplitude of 240 kA, peak stored energy up to 864 kJ, pulsewidth at 10% of peak power of 360 mus, dimensions of 2.3 times 1.5 times 2.5 m3, and weight of ~2500 kg. In nominal regime (24-kV charging voltage, 40-m length cables), the energy delivered to flashlamps in each channel is 74 kJ (86% efficiency). No failures were observed in more than 1000 test shots, and all parameters of the CBM are well within the requirements. Detailed description of the module design, performance, and test results are stated in this paper.

The "Laser Megajoule" (LMJ) in CEA/CESTA - Bordeaux is designed to deliver 240 laser beams and 7.5 kJ - 351 nm each to transmit 1.8 MJ on 0.3 mg Deuterium/Tritium encapsulated in gold micro-balloon. This project requires a carefully controlled energy, a high precision timing and extreme precisely positioned targets near the center of experiment chamber. This experiment will allow the complex physic understanding of inertial confinement fusion and high energy density. The result takes an active part in the validation of simulation program. One important challenge is to assure a good behavior of troublemaker and sensible components in a same working time. The main parts of LMJ spread on several typical areas with different levels of electromagnetic fields. This paper presents a description of nominal LMJ design, some specific results and the choice of electromagnetic field level for the future tests on components before their assembly in the building. For the all components, interfaces, cable and grounding system, the studies are established with results of "Line Integration Laser" (LIL), the first completed laser experiment, the tests of components in University of Rochester "Omega Laser", the industrial texts of normalization and simulation calculations.

Titan Pulse Sciences Division (Titan) has developed and extensively tested a scaled down version of the rotating arc gap (RAG) switch that had been previously considered for the National Ignition Facility laser system capacitor banks at Lawrence Livermore National Laboratory. The new switch is a candidate for the French CEA mega-Joule laser (LMJ) power conditioning system; switching 250 kA and < 75 Cb per shot at 24 kV with an expected 10,000 shot life before major maintenance.

A self-contained solid state trigger generator has been successfully implemented and life-tested with its companion rotating arc gap (RAG) coaxial switch. This is in response to CEA's request for a cost-effective, reliable, and maintenance-free global switching solution for the upcoming LMJ Facility in France. The trigger unit provides > 200 kV peak trigger pulse with < 350 ns risetime (10% to 90%) at the output of a 3 m long RG-218 cable. The slew rate of the trigger pulse required is ~1 kV/ns @100 kV peak amplitude. These parameters, pre-determined via RAG switch trigger tests, are adequate for precise command firing the switch operating at M=4 (pressure set so operating voltage is 25% of self-break voltage at that pressure) value. With 480 each of these integrated switching systems required for the LMJ power conditioning units (PCU), reliability of the triggering system is paramount to the successful outcome of the laser fusion experiments. The adopted design is an all solid-state approach lending itself to potential applications where ruggedness, precision, long maintenance-free life, and high reliability are essential.

The CEA is responsible for the Megajoule Laser (LMJ) facility. This facility is a large flashlamp pump laser (1.8 MJ optical output). CEA and THALES entered into a contract for the design and manufacturing of the pulsed power conditioning system. This PPCS is based on a modular design of 540 modules (450 MJ energy capacitor bank) in order to have a more flexible and safer facility. For the first step of the LMJ program, called /spl Lt/Ligne Integration Laser/spl Gt/ (LIL), one laser chain had been built. This paper describes the evolution of module design for LMJ and the results obtained on the LIL. The overall electrical performance measured meets the requirements.

Capacitor energy banks can be considered as power converters in which the energy storage is charged within a long time (some tenths of seconds) and the energy released within a short time (from microseconds to milliseconds). The converter function is provided by a capacitor, which has to withstand two constraints: 1. high stored energy which relates to electrostatics: a high electric field is applied to the dielectric of the capacitor. 2. high output current which relates to electrodynamics: stress is applied to the galvanic circuit of the capacitor. The evolution of the requirement in terms of stored energy (both increase of and density of) necessitates the most exhaustive analysis of the induced risks and consequences. This analysis has been conducted for the MegaJoule Laser Project. Its energy bank will store within one minute 450 MJ at 24 kV. Then, the bank should be able to deliver a 135 MA pulse current within 360 /spl mu/s. This study will analyze the failure modes of the capacitors and their effects will be experimentally verified.

CEA decided to realize the Megajoule Laser (LMJ) in two steps. In a first time, one laser chain will be built in the "Ligne d'Integration Laser" (LIL) at CEA CESTA. The LIL will allow components qualification before the realization of the thirty laser chains for the Megajoule Laser. CEA has consulted four companies to carry out the LMJ energy bank. Thomson-CSF DETEXIS has been chosen by CEA to realize a 450 MJ energy bank. The contract of LMJ energy bank realization gives the complete result responsibility to Thomson-CSF, according to CEA specifications. CEA gave Thomson-CSF the results of a three years LIMEIL Laboratory experimentation on several components, like power supply, capacitors, resistors, high energy switches and cabling system studies.