39 results found
King M, Butler NMH, Wilson R, et al., 2019, Role of magnetic field evolution on filamentary structure formation in intense laser-foil interactions, HIGH POWER LASER SCIENCE AND ENGINEERING, Vol: 7, ISSN: 2095-4719
Ting A, Hafizi B, Helle M, et al., 2016, Staging and Laser Acceleration of Ions in Underdense Plasma, 17th Advanced Accelerator Concepts Workshop (AAC), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
Chen Y-H, Helle M, Ting A, et al., 2016, Laser Acceleration of Protons with an Optically Shaped, Near-Critical Hydrogen Gas Target, 17th Advanced Accelerator Concepts Workshop (AAC), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
Pogorelsky IV, Babzien M, Ben-Zvi I, et al., 2016, Extending laser plasma accelerators into the mid-IR spectral domain with a next-generation ultra-fast CO2 laser, PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 58, ISSN: 0741-3335
King M, Gray RJ, Powell HW, et al., 2016, Ion acceleration and plasma jet formation in ultra-thin foils undergoing expansion and relativistic transparency, 2nd Workshop on European Advanced Accelerator Concepts (EAAC), Publisher: Elsevier, Pages: 163-166, ISSN: 0168-9002
At sufficiently high laser intensities, the rapid heating to relativistic velocities and resulting decompression of plasma electrons in an ultra-thin target foil can result in the target becoming relativistically transparent to the laser light during the interaction. Ion acceleration in this regime is strongly affected by the transition from an opaque to a relativistically transparent plasma. By spatially resolving the laser-accelerated proton beam at near-normal laser incidence and at an incidence angle of 30°, we identify characteristic features both experimentally and in particle-in-cell simulations which are consistent with the onset of three distinct ion acceleration mechanisms: sheath acceleration; radiation pressure acceleration; and transparency-enhanced acceleration. The latter mechanism occurs late in the interaction and is mediated by the formation of a plasma jet extending into the expanding ion population. The effect of laser incident angle on the plasma jet is explored.
Dover N, Cook N, Tresca O, et al., 2016, Optical shaping of gas targets for laser plasma ion sources, Journal of Plasma Physics, Vol: 82, ISSN: 1469-7807
We report on the experimental demonstration of a technique to generate steep densitygradients in gas jet targets of interest to laser plasma ion acceleration. By using anintentional low energy prepulse, we generated a hydrodynamic blast wave in the gas toshape the target prior to the arrival of an intense CO2 (λ ≈ 10 µm) drive pulse. Thistechnique has been recently shown to facilitate the generation of ion beams by shockwaveacceleration (Tresca et al. 2015). Here, we discuss and introduce a model to understandthe generation of these blast waves and discuss in depth the experimental realisationof the technique, supported by hydrodynamics simulations. With appropriate prepulseenergy and timing, this blast wave can generate steepened density gradients as short asl ≈ 20 µm (1/e), opening up new possibilities for laser-plasma studies with near-criticalgaseous targets.
Dover N, Palmer CAJ, Streeter MJV, et al., 2016, Buffered high charge spectrally-peaked proton beams in the relativistic-transparency regime, New Journal of Physics, Vol: 18, ISSN: 1367-2630
Spectrally-peaked proton beams of high charge (Ep ≈ 8 MeV, ∆E ≈4 MeV, N ≈ 50 nC ) have been observed from the interaction of an intense laser(> 1019 Wcm−2) with ultrathin CH foils, as measured by spectrally-resolved full beamprofiles. These beams are reproducibly generated for foil thicknesses 5-100 nm, andexhibit narrowing divergence with decreasing target thickness down to ≈ 8◦for 5 nm.Simulations demonstrate that the narrow energy spread feature is a result of bufferedacceleration of protons. The radiation pressure at the front of the target results inasymmetric sheath fields which permeate throughout the target, causing preferentialforward acceleration. Due to their higher charge-to-mass ratio, the protons outrun acarbon plasma driven in the relativistic transparency regime.
Cook N, Tresca O, Dover NP, et al., 2016, Hydrodynamic Shaping of Gas Jets for Laser Driven Shock Acceleration of Helium Ions, 16th Advanced Accelerator Concepts Workshop, Publisher: AMER INST PHYSICS, ISSN: 0094-243X
Powell HW, King M, Gray RJ, et al., 2015, Proton acceleration enhanced by a plasma jet in expanding foils undergoing relativistic transparency, New Journal of Physics, Vol: 17, ISSN: 1367-2630
Ion acceleration driven by the interaction of an ultraintense (2 × 1020 W cm−2) laser pulse with an ultrathin ($\leqslant 40$ nm) foil target is experimentally and numerically investigated. Protons accelerated by sheath fields and via laser radiation pressure are angularly separated and identified based on their directionality and signature features (e.g. transverse instabilities) in the measured spatial-intensity distribution. A low divergence, high energy proton component is also detected when the heated target electrons expand and the target becomes relativistically transparent during the interaction. 2D and 3D particle-in-cell simulations indicate that under these conditions a plasma jet is formed at the target rear, supported by a self-generated azimuthal magnetic field, which extends into the expanded layer of sheath-accelerated protons. Electrons trapped within this jet are directly accelerated to super-thermal energies by the portion of the laser pulse transmitted through the target. The resulting streaming of the electrons into the ion layers enhances the energy of protons in the vicinity of the jet. Through the addition of a controlled prepulse, the maximum energy of these protons is demonstrated experimentally and numerically to be sensitive to the picosecond rising edge profile of the laser pulse.
Tresca O, Dover NP, Cook N, et al., 2015, Spectral Modification of Shock Accelerated Ions Using a Hydrodynamically Shaped Gas Target, PHYSICAL REVIEW LETTERS, Vol: 115, ISSN: 0031-9007
Pogorelsky IV, Ben-Zvi I, Skaritka J, et al., 2015, New opportunities for strong-field LPI research in the mid-IR, Conference on Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Palmer CAJ, Dover NP, Pogorelsky I, et al., 2015, Manipulation of laser-generated energetic proton spectra in near critical density plasma, JOURNAL OF PLASMA PHYSICS, Vol: 81, ISSN: 0022-3778
Green JS, Dover NP, Borghesi M, et al., 2014, Enhanced proton beam collimation in the ultra-intense short pulse regime, PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 56, ISSN: 0741-3335
Pozimski JK, Aslaninejad M, Dover N, et al., 2013, A Ready-to-use Application of Laser-Plasma Accelerators using Gabor Lenses
Hughes C, Dover N, Najmudin Z, et al., 2013, Characterisation of Nitrogen Clusters and Gas Jet Targets Under Varied Nozzle Geometries
Robinson APL, Trines RMGM, Dover NP, et al., 2012, Hole-boring radiation pressure acceleration as a basis for producing high-energy proton bunches, PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 54, ISSN: 0741-3335
Palmer CAJ, Schreiber J, Nagel SR, et al., 2012, Rayleigh-Taylor instability of an ultrathin foil accelerated by the radiation pressure of an intense laser., Phys Rev Lett, Vol: 108
We report experimental evidence for a Rayleigh-Taylor-like instability driven by radiation pressure of an ultraintense (10(21) W/cm(2)) laser pulse. The instability is witnessed by the highly modulated profile of the accelerated proton beam produced when the laser irradiates a 5 nm diamondlike carbon (90% C, 10% H) target. Clear anticorrelation between bubblelike modulations of the proton beam and transmitted laser profile further demonstrate the role of the radiation pressure in modulating the foil. Measurements of the modulation wavelength, and of the acceleration from Doppler-broadening of back-reflected light, agree quantitatively with particle-in-cell simulations performed for our experimental parameters and which confirm the existence of this instability.
Dover NP, Najmudin Z, 2012, Ion acceleration in the radiation pressure regime with ultrashort pulse lasers, HIGH ENERGY DENSITY PHYSICS, Vol: 8, Pages: 170-174, ISSN: 1574-1818
Palmer CAJ, Schreiber J, Nagel SR, et al., 2012, Rayleigh-Taylor Instability of an Ultrathin Foil Accelerated by the Radiation Pressure of an Intense Laser, PHYSICAL REVIEW LETTERS, Vol: 108, ISSN: 0031-9007
Prasad R, Ter-Avetisyan S, Doria D, et al., 2012, Acceleration of ions up to 20MeV/nucleon in the ultrashort, high-intensity regime, 179th International School of Physics Enrico Fermi on Laser-Plasma Acceleration, Publisher: IOS PRESS, Pages: 213-220, ISSN: 0074-784X
Pogorelsky IV, Dover NP, Babzien M, et al., 2012, Ion Acceleration by Laser Hole-Boring into Plasmas, 15th Workshop on Advanced Accelerator Concepts (AAC), Publisher: AMER INST PHYSICS, Pages: 814-819, ISSN: 0094-243X
Prasad R, Ter-Avetisyan S, Doria D, et al., 2011, Laser driven ion acceleration from ultra thin foils in the ultra relativistic intensity regime, Pages: 141-144
Prasad R, Ter-Avetisyan S, Doria D, et al., 2011, Proton acceleration using 50 fs, high intensity ASTRA-Gemini laser pulses, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 653, Pages: 113-115, ISSN: 0168-9002
Prasad R, Andreev AA, Ter-Avetisyan S, et al., 2011, Fast ion acceleration from thin foils irradiated by ultra-high intensity, ultra-high contrast laser pulses, APPLIED PHYSICS LETTERS, Vol: 99, ISSN: 0003-6951
Pogorelsky IV, Polyanskiy MN, Babzien M, et al., 2011, Laser-induced cavities and solitons in overcritical hydrogen plasma, LASER PHYSICS, Vol: 21, Pages: 1288-1294, ISSN: 1054-660X
Najmudin Z, Palmer CAJ, Dover NP, et al., 2011, Observation of impurity free monoenergetic proton beams from the interaction of a CO2 laser with a gaseous target, 52nd Annual Meeting of the APS Division of Plasma Physics, Publisher: AMER INST PHYSICS, ISSN: 1070-664X
Streeter MJV, Foster PS, Cameron FH, et al., 2011, Relativistic plasma surfaces as an efficient second harmonic generator, NEW JOURNAL OF PHYSICS, Vol: 13, ISSN: 1367-2630
Palmer CAJ, Dover NP, Pogorelsky I, et al., 2011, Monoenergetic Proton Beams Accelerated by a Radiation Pressure Driven Shock, PHYSICAL REVIEW LETTERS, Vol: 106, ISSN: 0031-9007
Pogorelsky I, Polyanskiy M, Yakimenko V, et al., 2011, Proton- and x-ray beams generated by ultra-fast CO2 lasers for medical applications, Conference on Laser Acceleration of Electrons, Protons, and Ions and Medical Applications of Laser-Generated Secondary Sources of Radiation and Particles, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Borghesi M, Kar S, Prasad R, et al., 2011, Ion source development and radiobiology applications within the LIBRA project, Conference on Laser Acceleration of Electrons, Protons, and Ions and Medical Applications of Laser-Generated Secondary Sources of Radiation and Particles, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
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