arXiv subjects

B. Dromey

Publications and source records attributed to B. Dromey.

22 records · Page 2Linked to original sources

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↗

arXiv2007

Dynamic Control of Laser Produced Proton Beams

The emission characteristics of intense laser driven protons are controlled using ultra-strong (of the order of 10^9 V/m) electrostatic fields varying on a few ps timescale. The field structures are achieved by exploiting the high potential of the target (reaching multi-MV during the laser interaction). Suitably shaped targets result in a reduction in the proton beam divergence, and hence an increase in proton flux while preserving the high beam quality. The peak focusing power and its temporal variation are shown to depend on the target characteristics, allowing for the collimation of the inherently highly divergent beam and the design of achromatic electrostatic lenses.

physics.plasm-ph↗

arXiv2007

Bright quasi-phasematched soft x-ray harmonic radiation from Argon ions

Selective enhancement (>10^3) of harmonics extending to the water window (~4nm) generated in an argon gas filled straight bore capillary waveguide is demonstrated. This enhancement is in good agreement with modeling which indicates that multimode quasi-phasematching (MMQPM) is achieved by rapid axial intensity modulations caused by beating between the fundamental and higher order capillary modes. Substantial pulse-energies (>10nJ per pulse per harmonic order) at wavelengths beyond the carbon K-edge (~4.37nm, ~284eV) up to ~360eV are observed from argon ions for the first time.

physics.plasm-ph↗

arXiv2007

Quasi-phasematching of harmonic generation via multimode beating in waveguides

A new scheme for quasi-phasematching high harmonic generation (HHG) in gases is proposed. In this, the rapid variation of the axial intensity resulting from excitation of more than one mode of a waveguide is used to achieve quasi phasematching. Numerical modeling demonstrates enhancement of the harmonic signal over that achieved for a single coherence length by factors >10^4.

physics.plasm-ph↗