Laser-driven photoelectron induced pulsed X-ray source for energy dispersive X-ray spectroscopy and radiography applications

We present the details of a nanosecond pulsed X-ray source developed for energy dispersive X-ray spectroscopy (EDX) and low-dose fast radiography. The source is based on the illumination of a metal photocathode, placed in a Pierce-type electron gun geometry, with a low energy Nd:YAG laser, delivering 266 nm wavelength pulses with a time duration of 5 ns and energy in the range of 12–100 mJ. The emitted nanosecond pulsed photoelectrons are accelerated up to 30 keV energy and impinge on the cathode. The influence of laser energy and electron accelerating potential on the X-ray flux is investigated. The X-ray flux is found to follow power law as Ix∝(El)α, where El is the laser energy and α depends on the accelerating potentials. The preliminary experiments confirm that this source can be used for increased sensitivity EDX analysis as compared to the commercial secondary electron microscope. Our radiography results indicate that the use of alkali-based photocathodes can facilitate capturing a radiograph in a single laser pulse of a nanosecond time duration.