Development of control mechanisms for a laser wakefield accelerator-driven bremsstrahlung x-ray source for advanced radiographic imaging

Abstract

A high power laser (TW) was used to accelerate electrons in a laser-driven wakefield accelerator. The high energy electrons were then used to generate an X-ray beam by passing them through a converter target. This bremsstrahlung source was characterised and used to perform penetrative imaging of industrially relevant samples. The photon spectrum had a critical energy in excess of 100 MeV and a source size smaller than the resolution of the diagnostic (150 µm). Simulations indicate a significantly smaller source is achievable. Variations in the X-ray source characteristics were realised through changes to the plasma and converter parameters while simulations confirm the adaptability of the source. Imaging of high areal density objects with 150 µm resolution was performed, demonstrating the unique advantages of this novel source.

Ultrafast imaging for uncovering laser–material interaction dynamics

“…Generally, continuous photography with a μs–ms frame interval can be realized using a long pulse or continuous X‐ray light source, such as a synchrotron radiation light source, combined with shutter exposure time control of the X‐ray camera, as shown in Figure 5A 61 . Alternatively, a plasma source excited by an intense laser pulse can generate an X‐ray pulse with an ultrafast temporal resolution based on mechanisms such as Compton scattering, 63 wakefield acceleration, 64 and bremsstrahlung, 62 which can achieve fs‐ps temporal resolution. Figure 5B shows a typical laser wakefield accelerator‐driven bremsstrahlung X‐ray source for advanced radiographic imaging.…”

“…(B) Synchrotron radiation source. Reproduced under terms of the CC‐BY license 62 . Copyright 2020, The Authors, published by IOP…”

A laser-plasma platform for photon-photon physics

“…By translating the target so that it was only partially intercepting the γ beam profile we could vary the number of positrons produced and transported to the detectors. Only a limited number of shots ( 10) were taken at each position. The γ background was subtracted from the CsI data using the method describe in section 6.…”

“…Today however, bright electron beams with GeV energies can be produced over a few centimetres by laser wakefield acceleration (LWFA) [5,6]. These electron beams can be used to produce brilliant γ ray beams by bremsstrahlung [7,8,9,10] and inverse Compton scattering [11,12,13]. Colliding such brilliant γ ray photons with a suitable x-ray photon field could be a viable route to study two-photon physics in the laboratory for the first time [14,15].…”

An optimized online filter stack spectrometer

“…Recently, some online FSSs based on scintillators have been developed [35][36][37][38] , where the chargecoupled devices (CCDs) or complementary metal-oxidesemiconductor (CMOS) cameras are used as the photoelectric converters. We note that the scintillator-based FSS has already been used in the leading-edge experiments [39][40][41] , showing excellent performance in the detection of wideband X/γ-rays with high repetition rate. However, there are some aspects of the currently developed online FSS technique that need improvement.…”