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GREC, an acronym for "Generateur de Radiographie EClair" was designed for visualisation, measurements and studies on dynamic behavior of materials under high explosive loading. GREC was built in 1974 by Physics International for the CEA. Since the first operating time, 1975, this facility has been improving, taking advantage of progress in the techniques involved, especialy focusing and transport of intense electron beams.
In this paper, we describe the X-ray machine and give some details on the image detection device.
The pulse generator, a 80 stages Marx Generator can deliver a peak voltage of 9 MV in 1.2/us by series erection of 2 x 80 capacitors charged at + 60 kV. The Hulse-forming network, a tri-axial Blumlein, delivers a 80 ns-pulse via a 26 ohms impedance transmission line to the transport section. This transport section is a 24 cm diameter, 2 meters long, magnetic-insulated coaxial line. At the end, the X-ray radiation is emitted by bremstrahlung of the electrons impinging the tantalum anode of the dis-charge diode. The main specifications are :
- electrical : 7 -MV - 180 kA - 30 ns
- X-ray : Diode 1 : 400 R at 1 meter ; spot size : 20 mm
Diode 2 : 100 - 300 R at 1 meter ; spot size : 4-8 mm
The image acouisition device has been designed for X-raying of objects under loading of un to 50 kg of high explosives. In the paper, we give some details on the exnerimental arrangement used. Despite the severe environmental shock constraints, reasonable measurements of line-integrated density are possible.
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