Research towards high-repetition rate laser-driven X-ray sources for imaging applications

Abstract

Laser wakefield acceleration of electrons represents a basis for several types of novel X-ray sources based on Thomson scattering or betatron radiation. The latter provides a high photon flux and a small source size, both being prerequisites for high-quality X-ray imaging. Furthermore, proofof-principle experiments have demonstrated its application for tomographic imaging. So far this required several hours of acquisition time for a complete tomographic dataset. Based on improvements to the laser system, detectors and reconstruction algorithms, we were able to reduce this time for a full tomographic scan to 3 minutes. In this paper, we discuss these results and give a prospect to future imaging systems. *

Design study for a compact laser-driven source for medical x-ray fluorescence imaging

“…On the one hand, more photons are emitted into higher harmonics (nE γ ), multiples of the required XFI photon energy. On the other hand, due to the pulsed nature of the laser and the longitudinal and transverse intensity profile, broadening of the x-ray spectrum increases [66,71,75,[81][82][83][84][85][86] as can be seen in nonlinear TS experiments [24,34,[39][40][41]. In a hypothetical laser of constant field amplitude, all electrons would experience the same amplitude during the interaction and thus emit the same photon energy, according to Eq.…”

“…In recent years, the development of compact TS-based sources has become a wide research field. Different types of sources are investigated, driven by linear accelerators (linacs) [20][21][22][23][24][25][26][27][28], small-size synchrotrons (Lyncean [11,29], ThomX [30,31]) and laser-wakefield acceleration (LWFA) [32][33][34][35][36][37][38][39][40][41][42].…”

Attosecond betatron radiation pulse train

“…Sub-femtosecond high brightness X-ray pulses are in high demand by research communities in the fields of biology, material science or femtochemistry 1 , as well as by industry and medicine 2 . Such pulses can be used as a diagnostic tool to resolve the structure and dynamics of dense matter, proteins, and study fundamental physical phenomena such as chemical reactions, lattice vibrations or phase transitions.…”

“…During the acceleration process, the electron bunch undergoes transverse betatron oscillations due to the presence of the transverse electric field. As a result, betatron radiation [9][10][11] with a synchrotron-like 12 spectrum, typically in the X-ray range, is emitted.…”

“…The radiation spectrum is characterized by a critical energy, close to the peak of the synchrotron spectrum, given in practical units ω c (eV) = 5.24 × 10 −21 γ 2 n e (cm −3 )r β (µm) . The average photon number with energy ω c emitted by an electron is N X = 5.6 × 10 −3 N 0 K , where K = 1.33 × 10 −10 γ 1/2 n 1/2 e (cm −3 )r β (µm) is the strength parameter 13,14 . Several applications of such betatron sources have been demonstrated, e.g.…”