Michel Caron

Linear Transformer Driver (LTD) research for radiographic applications

URSA Minor is a 21-cavity Linear Transformer Driver (LTD) that has been built to evaluate LTD technology as a driver for flash radiography diode research. The LTD has been assembled and tested with initial testing being conducted at ±75 kV charge. In this configuration the generator has produced 1.7 MV on a 30-ohm MITL when driving an electron beam diode. Diagnostics during initial testing include cavity voltage, MITL currents, x-ray dose using TLDs, and x-ray dose rate using PIN diodes.

Study and optimization of negative polarity rod pinch diode as flash radiography source at 4.5 MV

The negative polarity rod pinch diode (NPRPD) is a potential millimeter spot size radiography source for high voltage generators (4 to 8 MV) [Cooperstein et al., “Considerations of rod-pinch diode operation in negative polarity for radiography,” in Proceedings of the 14th IEEE Pulsed Power Conference, 2003, pp. 975–978]. The NPRPD consists of a small diameter (few mm) cylindrical anode extending from the front end of the vacuum cell through a thin annular cathode, held by a central conductor. The polarity has been inverted when compared to the original rod pinch diode [Cooperstein et al., “Theoretical modeling and experimental characterization of a rod-pinch diode,” Phys. Plasmas 8(10), 4618–4636 (2001)] in order to take advantage from the maximal x-ray emission toward the anode holder at such a voltage [Swanekamp et al., “Evaluation of self-magnetically pinched diodes up to 10 MV as high resolution flash X-ray sources,” IEEE Trans. Plasma Sci. 32(5), 2004–2016 (2004). We have studied this diode at 4.5 MV...

Experimental study of self magnetic pinch diode as flash radiography source at 4 megavolt

The Self Magnetic Pinch (SMP) diode is a potential high-brightness X-ray source for high voltage generators (2–10 MV) that has shown good reliability for flash radiography applications [D. D. Hinchelwood et al., “High power self-pinch diode experiments for radiographic applications” IEEE Trans. Plasma Sci. 35(3), 565–572 (2007)]. We have studied this diode at about 4 MV, driven by the ASTERIX generator operated at the CEA/GRAMAT [G. Raboisson et al., “ASTERIX, a high intensity X-ray generator,” in Proceedings of the 7th IEEE Pulsed Power Conference (1989), pp. 567–570]. This generator, made up of a capacitor bank and a Blumlein line, was initially designed to test the behavior of electronic devices under irradiation. In our experiments, the vacuum diode is modified in order to set up flash radiographic diodes. A previous set of radiographic experiments was carried out on ASTERIX with a Negative Polarity Rod Pinch (NPRP) diode [B. Etchessahar et al., “Study and optimization of negative polarity rod pinch d...

Commissioning and power flow studies of the 2.5-MeV Ursa Minor LTD

Ursa Minor is a 21-cavity Linear Transformer Driver (LTD) that has been built to evaluate LTD technology as a driver for electron beam diode research. Initial testing has been conducted at ±90 kV charge. In this configuration the generator has produced 2.0 MV on a 30-ohm MITL when driving an electron beam diode. 2-D PIC simulations of the MITL predict about 15% higher peak voltage and current than seen in experiments. Monte Carlo radiation transport calculations indicate the measured x-ray dose is consistent with the measured diode current and voltage. Triggering experiments indicate that single LTD cavities are insensitive to trigger polarity, whereas the 21-cavity Ursa Minor shows clear sensitivity to trigger polarity.

Negative polarity rod pinch diode experiments on the astertx generator

ASTERTX is a 6MV Marx+Blumlein X-ray generaton, dedicated to the testing of electrical components. For our experiments, the vacuum diode has been modified in order to set up a flash radiographic diode. The negative polarity rod pinch diode (NPRPD) has been tested on this generator since 2004. The polarity has been reversed from previous experiments2, in order to take advantage from the maximal X-ray emission toward the anode holder at such a voltage. The main goals of these new experiments are a better understanding of the physical phenomena, by the use of new diagnostics as a 4 images high speed camera, a streak camera and vacuum voltage probes.