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Cylindrical reflex triodes (CRTs) driven by a pulsed power generator can produce relatively low-endpoint X-ray spectra (~250 keV) that can be suitable for certain radiation–matter interaction studies. CRTs have several advantages over other reflex triode configurations, the most significant being the ability to operate multiple concentric CRTs, connected either in parallel or in series. Such configurations can result in increased X-ray output without increasing the endpoint or changing the pulsed-power generator. This article describes results from, and modeling of, experiments employing a single CRT and two CRTs in a series configuration. The modeling includes an analytic, physics-based model of CRT electrical operation; measured and calculated radiation distributions and spectra; and predicted effects of several configuration variations.

AWE is replacing its current Mevex X-ray machine (∼800kV, 35kA, 60ns pulse) to improve reliability and maintainability. A design using a Linear Transformer Driver (LTD) insulated with dry air at atmospheric pressure has been developed by ITHPP. A testbed using 3 cavities, made from 2 bricks of two GA35460M 8nF, 100kV capacitors, a multigap multichannel switch and a magnetic core, has been developed and extensively tested [1]. This led to the development of the full generator that uses 17 cavities in series to produce an 800kV output voltage on a vacuum insulated line and a 23–25Ω diode. The ∼4.3m long inner stalk is cantilevered by the back of the pulser and is positioned by a 3 point adjustable support. This setting is completed by 2 internal tensioning cables to compensate for flexing and provide fine adjustment of the diode end. The assembly of the generator has been done on the 1st half of 2015. The machine can be operated with negative and positive polarity outputs to satisfy operational requirements given by AWE. The tests results of this generator in both polarities are presented in terms of output performances. The reproducibility and reliability of the full system is also analyzed.

AWE is looking to replace its current Mevex X-ray machine (∼800kV, 35kA, 60ns pulse) to improve reliability and maintainability. A design using an LTD insulated with dry air at atmospheric pressure has been proposed by ITHPP. A testbed using 3 cavities, made from 2 bricks of two GA35460M 8nF, 100kV capacitors, a multigap multichannel switch and a magnetic core, has been developed and extensively tested. The 3 cavities have been fired on a single low inductance resistive load made from a single volume of electrolytic solution. With a ∼4.2Ω load, the 3 cavities deliver under vacuum ∼145kV, 35kA, in a 84ns pulse (at FWHM). The system proves to operate with high reliability, high reproducibility (

A 1 MV linear transformer driver (LTD) generator has been manufactured by ITHPP and SEIV, and delivered to CEA/DIF/Polygone d'Experimentation de Moronvilliers, in order to demonstrate the capability of this technology for flash X-ray radiography applications. This generator is composed of 10 cavities; each cavity includes 16 bricks representing two capacitors (GA 35436, 100kV, 8nF) and one multi-gaps air pressurized switch. To reduce the resistive losses in the switches, the inter-electrode gaps have been reduced from 6 mm in initial design to 4 mm, and the dry air pressure has been slightly increased. Each cavity has been tested individually on an automated testbed using a low inductive resistive load (∼1.2nH) and extensive diagnostics, including a set of sixteen capacitive probes in front of each switch to control their timing sequence. The cavities deliver more than 100kV at ±100kV charging voltage into a matched load of 0.55–0.6Ω in a ∼70-ns FWHM pulse. Around 300 shots have been made on each cavity (to condition the switches) before their integration into the generator.

Summary form only given. For future hydrodynamic experiments, an 8 MV radiographic machine, IDERIX, will be developed for the CEA/PEM. This machine will be composed by ~80 super fast LTD (linear transformer driver) stages. The output voltage of each of these stages (100 kV -75 ns) will be inductively added along a ~20 m stepped magnetically insulated transmission line to deliver the power up to the beam diode. In each stage, 16 bricks, made with two 8 nF capacitors (that can be charged up to plusmn100 kV) and one multi-channels multi-gaps switch, are arranged in parallel (with a star pattern). The number of bricks is chosen to adapt the stage impedance to the diode impedance and operate the LTD generator close to matched mode. Moreover, new magnetic cores using a thinner ferromagnetic tape (50 mum) will allow reducing the losses and improving the performances of the generator. The insulation inside the stage will be done using dielectric oil. Downstream, the vacuum transmission line will be connected to a diode. The negative rod pinch diode geometry has been studied and tested at 6 MV on the ASTERIX generator since 2004. In 2006, a 2 meters MITL with the same geometry than the foreseen end of the future LTD generator, has been added to ASTERIX to mimic the power feed. Thus a dose of 70 rads at 1 m and a spot size of 2 mm (LANL/CEA definition) have been obtained. Simulations predict that those performances should increase at 8 MV and should satisfy die specification asked to IDERIX. A global description of the machine followed by an update on generator and diode studies will be proposed.

Sphinx is the new name of the facility developed for soft X-ray production at Centre d'Etudes de Gramat (CEG), France. This facility is based on the ECF2 generator which was designed as a 1-3 MJ, 1 mus rise time, 5-10 MA current driver. In this paper, we present a detailed view of the technology used for the capacitor bank. Some details are also given for the central vacuum part and for the Z-pinch load. The capacitor bank is based on the 1 mus LTD technology; it now stores 1 MJ with 12 parallel branches and 8 LTD stages per branch (each stage charged under 50 kV). We plan to have within the next 2 years, 3 MJ stored energy with 16 branches, 10 LTD stages per branch (charged under 70 kV). Improvements made on the LTD stages are presented. The modularity of this driver and the design of central vacuum part allow to test different schemes: flux compression up to 2003 [1] and direct drive Z-pinches now. We give details on the mechanical arrangements and some examples of experimental results

Summary form only given. This paper discusses preliminary experiments carried out with the SPHINX generator at CEG and analyzes the potential of these sources with implosion time increased up to 800 ns. SPHINX generator (1MJ stored energy, 1 ms current rise time) is used to implode single or nested aluminum wire arrays in direct drive mode with 3.8 MA maximum current. Different designs of double-shell Z-pinches were tested: outer radius 6 to 7 cm, inner radius 3 to 3.7 cm, outer mass 0.2 to 1.7 mg, inner mass 0.3 to 0.8 mg, outer wires number 16 to 216, inner wires number 48 to 72. The benefit of using nested arrays configuration was proved for the stabilization and reproducibility of the source. The dynamic of the implosion is studied with 1D and 2D visible camera and X-UV time-integrated pin-hole cameras. The X-ray emission is qualified with time resolved resistive bolometry, filtered detectors (diamond PCDs, XRDs) and time integrated crystal spectrometer.

Summary form only given. Sphinx is the new name of the facility developed for soft X-ray production at Centre d'Etudes de Gramat (CEG), France. This facility is based on the ECF2 generator which was designed as a 1-3 MJ, 1 /spl mu/s rise time, 5-10 MA current driver. In this paper, we present a detailed view of the technology used for the capacitor bank, for the central vacuum part and for the Z-pinch loads. The capacitor bank is based on the 1 /spl mu/s LTD technology; it now stores 1MJ with 12 parallel coaxial lines and 8 LTD stages per line (charged under 50 kV). We plan to have within the next 2 years, 3 MJ stored energy with 16 lines, 10 LTD stages per line (charged under 70 kV). Improvements made on the LTD stages (8 /spl mu/F, 16 nH, 7.5 m/spl Omega/) and on the trigger system are presented. The modularity of this driver and the design of central vacuum part allow to test different power amplification or direct drive schemes: flux compression and now direct drive Z-pinches are the main experiments. Simple and nested aluminum wire arrays designed for K-shell radiation with implosion time as long as 800 ns were tested. We give details on the mechanical arrangements and some experimental results obtained in 2003 and beginning of 2004.

Summary form only given. We present the results obtained during the ASTERIX generator experiment at CEG. B field generation is the main technological issue. A 400 kJ capacitor bank connected to different solenoid designs allowed 27 T to be achieved (maximum on axis) inside a 40 mm diameter vacuum cell. An effort has been made to calibrate the electrical diagnostics to evaluate diode impedance. X-ray diagnostics measured the horizontal and vertical spot size, dose on the axis and dose rate. Simulations using the Lsp code were used to design the geometries and results were compared to the experimental data. CEA/DAM is interested in a magnetically immersed diode for radiography dynamic experiments.

GEPI is a pulsed power generator developed by ITHPP for Centre d'Etudes de Gramat (CEG), devoted to isentropic compression experiments in the 1 Gpa to 100 Gpa (IMbar) range, and to non shocked high velocity flyer plates in the 100 m/s to 17 km/s range. The main idea is to generate a high magnetic pressure in a strip line where the samples are located. The whole design is based on low inductance technologies. Depending on the load, the current reaches between 3 and 4 MA in 600 ns. The entire design has been done in a cost effective way and in order to achieve an easy-to-use capability. A description of the generator is shown and typical results of the studies led by CEG are presented. The matters of concern are equations of state, phase transitions and impact of high velocity flyer plates.

The future of PRS programmes is oriented towards very high pulsed power generators of few tens of MJ. At the present moment SATURN and mainly PBFA2-Z are at the edge of this range. It may happen that their technologies, even if they produce excellent results, are not easily extrapolable to higher power, in terms of cost, volume and efficiency. From this investigation, one may conclude that meeting requirements of future powerful plasma radiation sources needs to develop new technological concepts, in order to deliver the appropriate power to a Z-pinch load at affordable cost. This is the main motivation of the SYRINX program which was initiated by the French Defense Department in 1993. The Centre d'Etude de Gramat was asked to realize this research and development program in order to prepare the construction of future large pulsed power facilities for X-rays production which could be used by several customers. The technical specifications and program strategy for SYRINX are outlined as are the main components (HAEFELY-TRENCH capacitors, multigap multichannel coaxial switch and linear transformer driver prototype). The GSI generator prototype and plasma opening switch approach are discussed, as are diagnostics and numerical simulations.

The research module GSI (Generator a Stockage Inductif), a 640 kJ inductive energy storage generator, is one of the two prototype candidate to bring the future MAG3 z-pinch load driver into operation. The GSI is made of 4 capacitor banks, a water transmission line, a vacuum storage line and a plasma opening switch. Results of parametrical circuit simulations that have been performed on SABER and SCREAMER to choose its electrical features are given. Also, design details of each element and schedules are presented.

Summary form only given, as follows. ASTERIX is a high-voltage (6 to 7 MV), /spl sim/60-/spl Omega/, /spl sim/50-ns FWHM pulse generator located at the Centre d'Etudes de Gramat (CEG) in Gramat, France. It has been recently used for the first evaluation of the rod-pinch electron-beam diode as a source for high-resolution, penetrating flash radiography at up to 4 MV (on a 40 to 50-/spl Omega/ load). For this evaluation, the generator was operated in positive polarity, i.e., with positive high voltage applied to the inner coaxial electrode. This had never been done before on ASTERIX. Also, it was necessary to eliminate pre-pulse with a vacuum pre-pulse switch to achieve the desired diode behavior. To evaluate the diode physics, the current and voltage at the diode load must be determined. The electrical length of the vacuum section, the front-end architecture, and the design of the voltage probe located on the oil side of the vacuum/oil interface present difficulties in determining an equivalent circuit for inferring the load-voltage time history. In this paper, the modifications made to the ASTERIX generator for this rod-pinch evaluation will be discussed. The limitations encountered will be reviewed and ideas for improvement will be suggested. Also, the design of the rod-pinch hardware will be presented. We will describe the approach taken to determine the load-voltage time history and present comparisons between the data and circuit modeling using a physics-based rod-pinch model. The effects of the pre-pulse on the diode behavior and the performance of the pre-pulse switch will also be presented.

Summary form only given, as follows. The rod-pinch electron-beam diode as a source for high-resolution, penetrating flash radiography at voltages between 2 and 4 MV has been evaluated on the ASTERIX generator (6 to 7 MV, /spl sim/60 /spl Omega/, /spl sim/50-ns FWHM) located at the Centre d'Etudes de Gramat (CEG) in Gramat, France. This generator was modified for positive polarity operation, and a rod-pinch diode load was fielded. Diagnostics for this load include current and voltage probes to measure the diode electrical behavior, TLDs and RPLs to measure the radiation dose, pin diode and scintillator/photodiode detectors to determine the radiation time-history, two pinhole-cameras to image the radiation source, and a I-m radius tungsten "rolled edge" to measure the source diameter. Successful rod-pinch operation was achieved at 4 MV. An intense pinch and radiation emission was produced at the tip of the anode rod. Doses of up to 20 R were produced at I in from the rod-pinch tip in the forward direction. The dose/charge scales quadratically with the diode voltage from 1.5 to 4 MV. These data can also be fit by a radiographer's equation. For a 1-mm diameter tapered anode rod, the source diameter in the forward direction is 0.8 mm (FWHM of the derivative of the measured edge spread function). The source diameter scales linearly with rod diameter for rods from 0.5 to 2.0 mm in diameter. The source distribution appears to have a Bennett profile. The angular distribution of the radiation was measured with three pin diode detectors and will be discussed. Finally, results from this experiment will be compared with other rod-pinch results at lower voltage.

Summary form only given. The main goal of the presented HPP generator is to produce quasi-isentropic magnetic pressure ramps. This magnetic pressure should reach several hundreds of kbar for a generic copper sample of several tens of mm/sup 2/. This device will be a proof of principle of the use of compact (and then low cost) HPP generator to study high pressure dynamic behavior of materials. The peak current will reach at least 4 MA for a rise time varying from 180 ns to 300 ns. The dimensions of the generator will be a 5m/spl times/5m square based on a strip line design with solid dielectric insulation. 26 to 28 elementary generators made by HCEI, including multi gaps, multi channels switches, will be connected in parallel around the strip line. The technology used allows compactness of the generator and minimizes side equipment, avoiding use of pressurized gas, oil and vacuum. A peaking capacitor can be used to shape the current pulse. The paper present the features and the technology of the generator. Also, the first experimental results will be shown and the potentialities for material studies will be described.

A series of collaborative experiments on complex plasma loads have been carried out on the large inductive energy storage (IES) generator, GIT-4, over the last three years. The aim of the experiments is to explore the different configurations for the formation of ultra-high energy density plasmas in high voltage pulsed power systems by direct electromagnetic energy coupling. In this paper, the authors present some of the underlying philosophy on these experiments and the results obtained. Particular emphasis is placed on the pulsed power aspects and the effect of source-load coupling.