Patrick Eyl

Long Life Rotating ARC Gap Coaxial Switch for MEGA-AMP, Kilo-Coulomb, High Action Switching of Multi-MJ Capacitor Banks

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.

Prototype of a high power compact Marx generator for microwave applications

A compact pulsed power system is described. This system has been built to drive low impedance HPM sources (vircator, MILO). It consists of two Marx generators in parallel. Each Marx contains 13 bipolar (/spl plusmn/ 50 kV) stages of capacitors and switches placed in a tank filled with dielectric oil. This system stores 10 kJ and is capable of delivering a current up to 50 kA at 800 kV to a matched load. The rise time of the current is less than 100 ns. The Marx generators and the vacuum interface have a diameter of 0.8 m and a total length of 2 m. The voltage is monitored inside the oil tank by using a resistive divider, and the current is measured under vacuum with a Bdot probe. In this paper we present experimental results with a resistive load as well as data obtained when the obtained Marx generator is coupled to HPM tubes.

Sub Microsecond Rise Time, 200kV Peak, Modular Solid State Trigger Unit for Rotating ARC Gap Switch Operation

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 CEAs 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.

Pulsed power conditioning system for the Magajoule laser

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 Bank Module for Multi Megajoule Energy Storage

Within the context of the Pulsed Power Conditioning System (PPCS) development undertaken by the CEA for the Megajoule laser (LMJ) facility [1], a new capacitor bank module (CBM) has been developed by the IHCE (Tomsk) and ITHPP (France). Full PPCS of the LMJ consists of 480 CBM. Two CBMs were produced and tested in Tomsk. Main parts of the CBM are: HV power supplies, Command Control system, air conditioning system, capacitor block, and cables delivering the energy to a load.

Effects of the Reflector Design on the Flash Lamps Developed for the LMJ

Summary form only given. When operating the LIL, which is the prototype of the LMJ, we have observed an unexpected behaviour of several flash lamps after a few hundreds of shots. A whitening appeared near the anode, constituted of a deposition of SiO2 molecule in the inner part of the quartz tube. An investigation of the performance of these lamps was performed in terms of the emitted spectrum. We have shown that the pollution is not yet enough to affect the pumping efficiency of the lamp: the emitted light is only diffused. Nevertheless, because we need to guarantee their behaviour for thousands of shots, we recently started experiments in order to understand the whitening, and to intent to suppress it. In this paper, we present these studies. In particular, we show that the reflector design has a strong influence on the plasma formation inside the lamp. Photographs of the lamp discharge indicate that the geometry of the system lamp-reflector influences the homogeneity of the plasma. We think that regions where there are high plasma densities contribute to the whitening. We are carrying-on experiments with a full-scale LMJ amplifier prototype to test the new reflector design.

SINAPS 2000: An 1MJ, 2 MA inductive store/opening switches generator

In order to build an 1 MJ, 2 MA, 1 /spl mu/s pulsed power generator based on the use of inductive storage and plasma opening switches (POS), an R&D program was carried out at CEA-CESTA. This paper presents the results obtained with three mock-ups. Some critical points of this type of generators were studied with few components (16 capacitors and 8 switches). The first configuration (360 kV, 900 kA on a short circuit, 0.8 /spl mu/s) consisted of 4 Marx generators with two-stage capacitor banks to test the switches and evaluate the self-inductance of one stage. The second configuration (180 kV, 1.4 MA on a short circuit, 1.4 /spl mu/s) consisted of a capacitor bank using 8 Marx generators of one stage to study parallel Marx generator triggering. The authors also tested a POS stage on this experimental set-up. In the third configuration (720 kV, 400 kA), the capacitor bank was made of 2 Marx generators of 4 stages in order to study the voltage strength of the circuit components. In conclusion, the authors present the design and the progress in the mounting of the whole generator.

Performances of AMBIORIX [pulsed power generator]

AMBIORIX is a high pulsed power generator designed and built by the HPP team of Valduc CEA center in 1985. This generator is now located in CESTA, a center of CEA near Bordeaux (France). AMBIORIX is formed with a Marx generator (maximum energy storage=300 kJ), water coaxial and triaxial lines. Output parameters are: 0,5 /spl Omega/ impedance; 1.2 MV diode voltage; 2.4 MA load current with a 40 nsec pulse duration. Three kinds of loads can be used: two bremsstrahlung diodes (V max=1.2 MV or V max=400 kV) and a ZPINCH diode. In this paper, the authors describe the generator and give major characteristics of various loads.