arXiv subjects

M. Kaluza

Publications and source records attributed to M. Kaluza.

3 recordsLinked to original sources

arXiv2024

Limitations of emittance and source size measurement of laser-accelerated electron beams using the pepper-pot mask method

The pepper-pot method is a widely used technique, originally proposed for measuring the emittance of space-charge-dominated electron beams from radio-frequency photoinjectors. With recent advances in producing high-brightness electron beams via laser wakefield acceleration (LWFA), the method has also been applied to evaluate emittance in this new regime. Here, the limitations of this method for measuring the emittance of LWFA electron beams are investigated, particularly in parameter regimes where the true beam emittance is overestimated. Conducting an experiment at the JETi200 laser system, we measured an upper bound for the geometric beam emittance of $(26.2 \pm 7.3)$ $\mu$m mrad using the pepper-pot method. This result is consistent with GEANT4 Monte Carlo simulation of the pepper-pot diagnostic, with an input beam-emittance parameter that matches both PIC simulations of the laser-plasma accelerator and an independent measurement using the transient optical grating method.

physics.acc-ph↗

arXiv2024

All-optical source size and emittance measurements of laser-accelerated electron beams

Novel schemes for generating ultra-low emittance electron beams have been developed in past years and promise compact particle sources with excellent beam quality suitable for future high-energy physics experiments and free-electron lasers. Recent theoretical work has proposed a laser-based method capable of resolving emittances in the sub 0.1 mm mrad regime, by modulating the electron phase-space ponderomotively. Here we present a first experimental demonstration of this scheme using a laser wakefield accelerator. The observed emittance and source size is consistent with published values. We also show calculations demonstrating that tight bounds on the upper limit for emittance and source size can be derived from the 'laser-grating' method even in the presence of low signal to noise and uncertainty in laser-grating parameters.

physics.acc-ph↗

arXiv2010

Micron-scale Fast Electron Filamentation and Recirculation determined from Rear Side Optical Emission in High Intensity Laser-Solid Interactions

The transport of relativistic electrons generated in the interaction of petawatt class lasers with solid targets has been studied through measurements of the optical emission from their rear surface. The high degree of polarization of the emission indicates that it is predominantly optical transition radiation. A halo that surrounds the main region of emission is also polarized, and is attributed to the effect of electron recirculation. The variation of the amplitude of the transition radiation with respect to observation angle provides evidence for the presence of {$μ$m-size} filaments.

physics.plasm-ph↗