arXiv subjects

V. Tomkus

Publications and source records attributed to V. Tomkus.

3 recordsLinked to original sources

arXiv2026

Stable 50 MeV Beams from a 100 Hz Laser-Wakefield Accelerator Driven by an OPCPA Laser

We demonstrate a laser-wakefield accelerator driven by a high-repetition-rate optical parametric chirped-pulse amplification (OPCPA) laser, producing stable, quasi-monoenergetic electron beams at 100 Hz. Using 70 mJ, 8.1 fs laser pulses, we obtain 47 MeV electron beams with 15 pC charge and an intrinsic energy spread below 10%. Measurements over 10,000 consecutive shots show rms fluctuations of only 1.4% in peak energy and 12% in charge, together with low pointing jitter. Principal-component analysis reveals that the beam fluctuations are described by five physically interpretable modes, dominated by slow variations below 1 Hz. Particle-in-cell simulations reproduce the measured spectrum and show that nonlinear self-focusing localizes ionization injection, resulting in the observed narrow energy distribution. The demonstrated combination of electron energy, charge, beam quality, and stability represents a significant step toward high-average-power laser-plasma accelerators.

physics.acc-ph↗

arXiv2026

Demonstration of ultra-low emittance beams in a kHz laser wakefield accelerator and application to electron diffraction

We present a compact, cost-effective method for measuring the emittance of kHz-repetition-rate laser-wakefield accelerated electron beams using a permanent solenoid. The measured normalized emittance, $ε_n = 124\,\mathrm{nm \cdot rad}$ ($\simeq 0.04 π\,\mathrm{mm \cdot mrad}$) at $2.7\,$MeV, is comparable to that of ultra-low emittance radiofrequency guns used for electron diffraction. Leveraging this low emittance, we successfully applied the electron beam to electron diffraction. We demonstrate diffraction images obtained from a single-crystal silicon nanomembrane sample, clearly resolving diffraction peaks across multiple orders.

physics.acc-ph↗

arXiv2020

Optimization and stabilization of a kilohertz laser-plasma accelerator

Laser plasma acceleration at kilohertz repetition rate has recently been shown to work in two different regimes, with pulse lengths of either 30 fs or 3.5 fs. We now report on a systematic study in which a large range of pulse durations and plasma densities were investigated through continuous tuning of the laser spectral bandwidth. Indeed, two LPA processes can be distinguished, where beams of the highest quality, with 5.4 pC charge and a spectrum peaked at 2-2.5 MeV are obtained with short pulses propagating in moderate plasma densities. Through Particle-in-Cell simulations the two different acceleration processes are thoroughly explained. Finally, we proceed to show the results of a 5-hour continuous and stable run of our LPA accelerator accumulating more than $\mathrm{18\times10^6}$ consecutive shots, with 2.6 pC charge and peaked 2.5 MeV spectrum. A parametric study of the influence of the laser driver energy through PIC simulations underlines that this unprecedented stability was obtained thanks to micro-scale density gradient injection. Together, these results represent an important step towards stable laser-plasma accelerated electron beams at kilohertz repetition rate.

physics.acc-ph↗