A5039259658- Laser-Plasma Interactions and Diagnostics
- Atomic and Molecular Physics
- Laser Design and Applications
- Laser-Matter Interactions and Applications
- Laser-induced spectroscopy and plasma
- Advanced X-ray Imaging Techniques
- Solid State Laser Technologies
- Laser Material Processing Techniques
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Optical Systems and Laser Technology
- Diamond and Carbon-based Materials Research
- Plasma Diagnostics and Applications
- Analytical chemistry methods development
- Spectroscopy and Laser Applications
- Electron and X-Ray Spectroscopy Techniques
- Ion-surface interactions and analysis
- Nuclear Physics and Applications
- Advanced Optical Sensing Technologies
- Atomic and Subatomic Physics Research
- Crystallography and Radiation Phenomena
- Advanced X-ray and CT Imaging
- Radiology practices and education
- Ocular and Laser Science Research
- Advanced Fiber Laser Technologies
Queen's University Belfast
2009-2022
Centre of Plasma Physics - Institute for Plasma Research
1992-2016
Queens University
1977-2012
Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy
2005
University of Ulster
2004
Mater Health Services
2004
Université Paris-Sud
1990-2001
University of Essex
1996-1997
Rutherford Appleton Laboratory
1986-1997
Lawrence Livermore National Laboratory
1996-1997
Abstract All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams have limitations in terms of peak energy, bandwidth the energy spectrum beam divergence. Here we introduce concept versatile, miniature linear accelerating module, which, employing laser-excited electromagnetic pulses directed along helical path surrounding...
Tracking primary radiation-induced processes in matter requires ultrafast sources and high precision timing. While compact laser-driven ion accelerators are seeding the development of novel instantaneous flux applications, combining ultrashort laser pulse durations with their inherent synchronicity to trace real-time evolution initial damage events has yet be realized. Here we report on absolute measurement proton bursts as short 3.5±0.7 ps from solid target interactions for this purpose....
Amplification of spontaneous emission (ASE) at 23.6 nm has been studied in a Ge plasma heated by 1 TW infrared laser pulse. The exponent the axial gain reached 21 geometry with Fresnel number \ensuremath{\le}1. Two columns combined length up to 36 mm were used an extreme ultraviolet mirror giving double-pass amplification. Saturation ASE output was observed. beam divergence about 8\ifmmode\times\else\texttimes\fi{} diffraction limited brightness estimated ${10}^{14}$ W...
The construction of short-pulse tunable soft x-ray free electron laser sources based on the self-amplified spontaneous emission process will provide a major advance in capability for dense plasma-related and warm matter (WDM) research. 1013 photons 200-fs duration pulse that is from approximately 6 to 100 nm. Here we discuss only two many applications made possible WDM has been severely hampered by fact laser-based methods have unavailable because visible light not propagate at densities...
Extreme ultraviolet laser amplification has been observed for the C vi Balmer-\ensuremath{\alpha} transition at 18.2 nm, with use of a novel optical system to irradiate up 1 cm length carbon fiber target. The measurements were time resolved and indicated peak single-transit about 30 times.
A saturated nickel-like samarium x-ray laser beam at 7 nanometers has been demonstrated with an output energy of 0.3 millijoule in 50-picosecond pulses, demonstrating that operation a wavelengths shorter than 10 can be achieved. The narrow divergence, short wavelength, pulse duration, high efficiency, and brightness this make it ideal candidate for many applications.
Reflecting light from a mirror moving close to the speed of has been envisioned as route towards producing bright X-ray pulses since Einstein's seminal work on special relativity. For an ideal relativistic mirror, peak power reflected radiation can substantially exceed that incident due increase in photon energy and accompanying temporal compression. Here we demonstrate for first time dense electron mirrors be created interaction high-intensity laser pulse with freestanding, nanometre-scale...
Saturation of a low pump energy x-ray laser utilizing transient inversion mechanism on the $3p\ensuremath{-}3s$ transition at 32.63 nm in Ne-like Ti has been demonstrated. A close to saturation amplification was simultaneously achieved for $3d\ensuremath{-}3p,$ $J=\stackrel{\ensuremath{\rightarrow}}{1}1$ 30.15 nm. Small signal effective gain coefficients $g\ensuremath{\sim}46$ and $\ensuremath{\sim}35{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ gain-length products 16.7 16.9 these lines were...
We report the first demonstration of saturation in a Ni-like x-ray laser, specifically Ag laser at 14 nm. Using high-resolution spatial imaging and angularly resolved streaking techniques, output source size as well time history, divergence, energy, profile beam have been fully characterized. The intensity was measured to be about $70\mathrm{GW}{\mathrm{cm}}^{\ensuremath{-}2}$. narrow short pulse duration, high efficiency, brightness make it an ideal candidate for many applications.
The complex problem of a collisionally pumped Ne-like germanium laser is examined through several detailed models. central model EHYBRID; 1 1/2 D fluid code which self consistently treats the plasma expansion with atomic physics ion for 124 excited levels collisional radiative treatment. output EHYBRID used as data ray-tracing and saturation codes generate experimental observables. A description models given. investigated three-level approximation, steady state treatment time-dependent...
We have studied plasma waveguiding in soft x-ray laser experiments. A curved-slab target was used order to compensate for refraction a gradient-density plasma. In addition significant increase the intensity single-pass amplification, small beam divergence of less than 1 mrad has been stably generated double-pass amplification with curved target. The angular distribution double-passed indicates that amplified waveguide.
Laser implosion of 87-bar neon-filled glass microballoon targets produces a dense, cool plasma whose development in time and space is recorded by pulsed-x-ray shadowgraphy with soft x rays from separate laser-produced plasma. Compressed densities 4 g ${\mathrm{cm}}^{\ensuremath{-}3}$ are estimated the data comparison numerical simulations implosion.
A time-resolved measurement of the output from Ni-like Ag transient-collisional-excitation x-ray laser is described. An ultrafast streak camera was used to diagnose $J=\stackrel{\ensuremath{\rightarrow}}{0}1$ $4d\ensuremath{-}4p$ lasing line at 13.9 nm. The full width half maximum duration pulse measured be $1.9\ifmmode\pm\else\textpm\fi{}0.7 \mathrm{ps}$ optimum conditions pump irradiation. This shortest directly demonstrated date and illustrates great potential transient lasers as a high...
Abstract We report on experiments aimed at the generation and characterization of solid density plasmas free-electron laser FLASH in Hamburg. Aluminum samples were irradiated with XUV pulses 13.5 nm wavelength (92 eV photon energy). The duration a few tens femtoseconds pulse energy up to 100 µJ are focused intensities ranging between 10 13 17 W/cm 2 . investigate absorption temporal evolution sample under irradiation by use optical spectroscopy. discuss origin saturable absorption, radiative...
Relativistic laser plasmas have been shown to provide a robust platform for the generation of bright attosecond pulses via relativistically oscillating mirror and coherent wake emission mechanisms. Theoretical work, however, has an alternative method achieving this goal: dense nanobunch formation acceleration on timescales less than optical cycle (∼10−15 s) during relativistic laser–plasma interactions. This opens up exciting potential developing new ultrafast extreme ultraviolet XUV/x-ray...
We report the observation of amplification an xuv harmonic pulse in laser. The 21st a frequency-doubled 1.3-psec neodymium chirped-pulse-amplification laser was injected into gain region 18-mm-long Ga XXII x-ray amplifier. A approximately 3 recorded for harmonic, relative to unamplified 19th and 23rd harmonics when wavelength tuned overlap 25.11-nm J=2--1 transition.
We report on measurements of the saturated single frequency output a GeXXIII x-ray laser J=0\ensuremath{\rightarrow}1 transition at 19.6 nm from refraction compensating double target driven by 150 J energy 75-ps Nd-glass pulses. The 19.6-nm line completely dominated output. was measured to be 0.9 mJ in beam 6.6\ifmmode\times\else\texttimes\fi{}30 ${\mathrm{mrad}}^{2}$ divergence, corresponding conversion efficiency 6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$....
The L-shell soft-X-ray emission spectra of Cu, Zn, Ga, As, Br, Rb and Sr from laser-produced plasma sources were recorded with a convex-crystal spectrograph. spectrograms measured to provide wavelengths accurate ± 2 mÅ for neon-like 2p5-2p43s, 3d fluorine-like transitions. Theoretical oscillator strengths computed aid the classification experimental spectra.
The transient-excitation pumping scheme, in which a picosecond duration pulse rapidly heats the plasma preformed by low-intensity nanosecond pulse, was used to pump Ne-like germanium, J=0–1 transition at 19.6 nm. A small-signal gain coefficient of 30 cm-1 measured for targets ⩽5 mm long.