7th International Conference on Matter and Radiation at Extremes (ICMRE2024)

Two diode configurations have been used on the 10-MA pulsed power facility^[1,2] at Institute of Fluid Physics for producing large-area high-dose X-ray bremsstrahlung sources. A double-ring diode (DRD) consists of two nested annular triaxial diodes. Each triaxial diode produce an annular electron beam which strike a planar tantalum anode producing bremsstrahlung X-rays. The DRD is normally operated with diode voltage of ~1.5 MV. Th highest X-ray dose produced by DRD at 10 cm from anode plane, where a nearly uniform dose (with 2:1 uniformity) is available over an area of approximately 400 cm², is of ~100 Gy(LiF), corresponding to a peak dose rate of ~5×10⁹ Gy(LiF)/s with a pulse width of ~20 ns (FWHM). A cylindrical reflex triode (CRT) configuration is also developed on 10-MA facility. This configuration consists of three cylindrical coaxial thin anode tantalum targets, and each layer of tantalum targets and annular cathodes on both sides form a reflex triode configuration, which produces a greater output of warm X-rays (20-100 kev) than that is possible with DRD diodes. The CRT is normally operated with voltage of ~0.9 MV. The highest X-ray dose produced by CRT at 15 cm from cathode plane is 80 Gy(LiF), corresponding to a peak dose rate of ~1.5×10⁹ Gy(LiF)/s with a pulse width of ~45 ns (FWHM), and the area with 2:1 uniformity exceeds 500 cm². Further work includes optimizing the operation parameters of the DRD and CRT to improve the source intensity and stability, and exploring new techniques for generating warm X-rays.

Electron beam diode,Bremsstrahlung,Pulsed power