Christos Kamperidis | Searcharxiv

arXiv2021

Ultra-short, MeV-scale laser-plasma positron source for positron annihilation lifetime spectroscopy

Sub-micron defects represent a well-known fundamental problem in manufacturing since they can significantly affect performance and lifetime of virtually any high-value component. Positron annihilation lifetime spectroscopy is arguably the only established method capable of detecting defects down to the sub-nanometer scale but, to date, it only works for surface studies, and with limited resolution. Here, we experimentally and numerically show that laser-driven systems can overcome these well-known limitations, by generating ultra-short positron beams with a kinetic energy tuneable from 500 keV up to 2 MeV and a number of positrons per shot in a 50 keV energy slice \color{black} of the order of $10^3$. Numerical simulations of the expected performance of a typical mJ-scale kHz laser demonstrate the possibility of generating MeV-scale narrow-band and ultra-short positron beams with a flux exceeding $10^5$ positrons/s, of interest for fast volumetric scanning of materials at high resolution.

physics.acc-ph↗

arXiv2018

Laser wakefield acceleration with high-power, few-cycle mid-IR lasers

The study of laser wakefield electron acceleration (LWFA) using mid-IR laser drivers is a promising path for future laser driven electronaccelerators, when compared to traditional near-IR laser drivers uperating at 0.8-1 μm central wavelength (λlaser), as the necessary vector potential a_0 for electron injection can be achieved with smaller laser powers due to the linear dependence on λlaser. In this work, we perform 2D PIC simulations on LWFA using few-cycle high power (5-15 TW) laser systems with λlaser ranging from 0.88-10 μm. Such few-cycle systems are currently under development, aiming at Gas High Harmonics Generation applications where the favourable λlaser^2 scaling extends the range of XUV photon energies. We keep a_0 and n_e/n_cr (n_e being the plasma density and n_cr being the critical density for each λlaser) as common denominators in outr simulations, allowing for comparisons between drivers of different λlaser, with respect to the accelerated electron beam energy, charge, and conversion efficiency. While the electron energies are mainly dominated by the plasma dynamics, the laser to electron beam energy conversion efficiency shows significant enhancement with longer wavelength laser drivers.

physics.plasm-ph↗