Imperial College London

George Hicks

Faculty of Natural SciencesDepartment of Physics

Research Associate
 
 
 
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Contact

 

+44 (0)20 7594 7643g.hicks11

 
 
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Location

 

733Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

15 results found

Dover NP, Nishiuchi M, Sakaki H, Kondo K, Lowe HF, Alkhimova MA, Ditter EJ, Ettlinger OC, Faenov AY, Hata M, Hicks GS, Iwata N, Kiriyama H, Koga JK, Miyahara T, Najmudin Z, Pikuz TA, Pirozhkov AS, Sagisaka A, Schramm U, Sentoku Y, Watanabe Y, Ziegler T, Zeil K, Kando M, Kondo Ket al., 2020, Demonstration of repetitive energetic proton generation by ultra-intense laser interaction with a tape target, High Energy Density Physics, Vol: 37, Pages: 100847-100847, ISSN: 1574-1818

Journal article

Kondo K, Nishiuchi M, Sakaki H, Dover NP, Lowe HF, Miyahara T, Watanabe Y, Ziegler T, Zeil K, Schramm U, Ditter EJ, Hicks GS, Ettlinger OC, Najmudin Z, Kiriyama H, Kando M, Kondo Ket al., 2020, High-intensity laser-driven oxygen source from CW laser-heated titanium tape targets, Crystals, Vol: 10, Pages: 837-837, ISSN: 2073-4352

The interaction of high-intensity laser pulses with solid targets can be used as a highly charged, energetic heavy ion source. Normally, intrinsic contaminants on the target surface suppress the performance of heavy ion acceleration from a high-intensity laser–target interaction, resulting in preferential proton acceleration. Here, we demonstrate that CW laser heating of 5 µm titanium tape targets can remove contaminant hydrocarbons in order to expose a thin oxide layer on the metal surface, ideal for the generation of energetic oxygen beams. This is demonstrated by irradiating the heated targets with a PW class high-power laser at an intensity of 5 × 1021 W/cm2, showing enhanced acceleration of oxygen ions with a non-thermal-like distribution. Our new scheme using a CW laser-heated Ti tape target is promising for use as a moderate repetition energetic oxygen ion source for future applications.

Journal article

Nishiuchi M, Dover NP, Hata M, Sakaki H, Kondo K, Lowe HF, Miyahara T, Kiriyama H, Koga JK, Iwata N, Alkhimova MA, Pirozhkov AS, Faenov AY, Pikuz TA, Sagisaka A, Watanabe Y, Kando M, Kondo K, Ditter EJ, Ettlinger OC, Hicks GS, Najmudin Z, Ziegler T, Zeil K, Schramm U, Sentoku Yet al., 2020, Dynamics of laser-driven heavy-ion acceleration clarified by ion charge states, Physical Review Research, Vol: 2, Pages: 033081 – 1-033081 – 13, ISSN: 2643-1564

Motivated by the development of next-generation heavy-ion sources, we have investigated the ionization and acceleration dynamics of an ultraintense laser-driven high-Z silver target, experimentally, numerically, and analytically. Using a novel ion measurement technique allowing us to uniquely identify silver ions, we experimentally demonstrate generation of highly charged silver ions (Z∗=45+2−2) with energies of >20 MeV/nucleon (>2.2 GeV) from submicron silver targets driven by a laser with intensity 5×1021W/cm2, with increasing ion energy and charge state for decreasing target thickness. We show that although target pre-expansion by the unavoidable rising edge of state-of-the-art high-power lasers can limit proton energies, it is advantageous for heavy-ion acceleration. Two-dimensional particle-in-cell simulations show that the Joule heating in the target bulk results in a high temperature (∼10keV) solid density plasma, leading to the generation of high flux highly charged ions (Z∗=40+2−2, ≳10MeV/nucleon) via electron collisional ionization, which are extracted and accelerated with a small divergence by an extreme sheath field at the target rear. However, with reduced target thickness this favorable acceleration is degraded due to the target deformation via laser hole boring, which accompanies higher energy ions with higher charge states but in an uncontrollable manner. Our elucidation of the fundamental processes of high-intensity laser-driven ionization and ion acceleration provides a path for improving the control and parameters of laser-driven heavy-ion sources, a key component for next-generation heavy-ion accelerators.

Journal article

Passalidis S, Ettlinger OC, Hicks GS, Dover NP, Najmudin Z, Benis EP, Kaselouris E, Papadogiannis NA, Tatarakis M, Dimitriou Vet al., 2020, Hydrodynamic computational modelling and simulations of collisional shock waves in gas jet targets, HIGH POWER LASER SCIENCE AND ENGINEERING, Vol: 8, ISSN: 2095-4719

Journal article

Consoli F, De Angelis R, Robinson TS, Giltrap S, Hicks GS, Ditter EJ, Ettlinger OC, Najmudin Z, Notley M, Smith RAet al., 2019, Generation of intense quasi-electrostatic fields due to deposition of particles accelerated by petawatt-range laser-matter interactions, Scientific Reports, Vol: 9, ISSN: 2045-2322

We demonstrate here for the first time that charge emitted by laser-target interactions at petawatt peak-powers can be efficiently deposited on a capacitor-collector structure far away from the target and lead to the rapid (tens of nanoseconds) generation of large quasi-static electric fields over wide (tens-of-centimeters scale-length) regions, with intensities much higher than common ElectroMagnetic Pulses (EMPs) generated by the same experiment in the same position. A good agreement was obtained between measurements from a classical field-probe and calculations based on particle-flux measurements from a Thomson spectrometer. Proof-of-principle particle-in-cell simulations reproduced the measurements of field evolution in time, giving a useful insight into the charging process, generation and distribution of fields. The understanding of this charging phenomenon and of the related intense fields, which can reach the MV/m order and in specific configurations might also exceed it, is very important for present and future facilities studying laser-plasma-acceleration and inertial-confinement-fusion, but also for application to the conditioning of accelerated charged-particles, the generation of intense electric and magnetic fields and many other multidisciplinary high-power laser-driven processes.

Journal article

McIlvenny A, Doria D, Romagnani L, Ahmed H, Martin P, WIlliamson SDR, Ditter EJ, Ettlinger O, Hicks GS, McKenna P, Najmudin Z, Neely D, Kar S, Borghesi Met al., 2019, Absolute calibration of microchannel plate detector for carbon ions up to 250 MeV, 5th International Conference on Frontiers in Diagnostics Technologies, Publisher: IOP PUBLISHING LTD, ISSN: 1748-0221

Conference paper

King M, Butler NMH, Wilson R, Capdessus R, Grays RJ, Powell HW, Dance RJ, Padda H, Gonzalez-Izquierdo B, Rusby DR, Dover NP, Hicks GS, Ettlinger OC, Scullion C, Carroll DC, Najmudin Z, Borghesi M, Neely D, McKenna Pet 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

Journal article

Robinson TS, Consoli F, Giltrap S, Eardley S, Hicks G, Ditter E, Ettlinger O, Stuart N, Notley M, De Angelis R, Najmudin Z, Smith Ret al., 2017, Low-noise time-resolved optical sensing of electromagnetic pulses from petawatt laser-matter interactions, Scientific Reports, Vol: 7, ISSN: 2045-2322

We report on the development and deployment of an optical diagnostic for single-shot measurement of the electric-field components of electromagnetic pulses from high-intensity laser-matter interactions in a high-noise environment. The electro-optic Pockels effect in KDP crystals was used to measure transient electric fields using a geometry easily modifiable for magnetic field detection via Faraday rotation. Using dielectric sensors and an optical fibre-based readout ensures minimal field perturbations compared to conductive probes and greatly limits unwanted electrical pickup between probe and recording system. The device was tested at the Vulcan Petawatt facility with 1020 W cm−2 peak intensities, the first time such a diagnostic has been used in this regime. The probe crystals were located ~1.25 m from target and did not require direct view of the source plasma. The measured signals compare favourably with previously reported studies from Vulcan, in terms of the maximum measured intra-crystal field of 10.9 kV/m, signal duration and detected frequency content which was found to match the interaction chamber’s horizontal-plane fundamental harmonics of 76 and 101 MHz. Methods for improving the diagnostic for future use are also discussed in detail. Orthogonal optical probes offer a low-noise alternative for direct simultaneous measurement of each vector field component.

Journal article

Martin P, Doria D, Romagnani L, Ahmed H, McIlvenny A, Scullion C, Williamson SDR, Ditter EJ, Hicks G, Ettlinger OC, Scott GG, Symes DR, Booth N, Sgattoni A, Macchi A, Kar S, McKenna P, Najmudin Z, Neely D, Zepf M, Borghesi Met al., 2017, Transition to light sail acceleration using ultraintense femtosecond pulses

Presented are results from experimental campaigns undertaken on the Gemini laser system at the Central Laser Facility in the UK. In these experiments amorphous carbon targets ranging in thickness from 10nm to 100nm were irradiated with high contrast 40fs pulses with an intensity up to 1021 W/cm2, for both circular and linear polarisations and the resulting proton and ion spectra compared. Examining the highest energies achieved for a given polarisation and target thickness, allows to identify the transition from TNSA to LS. Observations of the optimal target thickness for ion acceleration are compared to analytical predictions from LS theory, in addition to results from Particle in Cell modelling.

Conference paper

Scullion C, Doria D, Romagnani L, Ahmed H, Alejo A, Ettlinger OC, Gray RJ, Green J, Hicks GS, Jung D, Naughton K, Padda H, Poder K, Scott GG, Symes DR, Kar S, McKenna P, Najmudin Z, Neely D, Zepf M, Borghesi Met al., 2016, Angularly resolved characterization of ion beams from laser-ultrathin foil interactions, 4th International Conference on Frontiers in Diagnostics Technologies, Publisher: IOP PUBLISHING LTD, ISSN: 1748-0221

Conference paper

Smyth AG, Sarri G, Vranic M, Amano Y, Doria D, Guillaume E, Habara H, Heathcote R, Hicks G, Najmudin Z, Nakamura H, Norreys PA, Kar S, Silva LO, Tanaka KA, Vieira J, Borghesi Met al., 2016, Erratum: “Magnetic field generation during intense laser channelling in underdense plasma” [Phys. Plasmas 23, 063121 (2016)], Physics of Plasmas, Vol: 23, ISSN: 1089-7674

Journal article

Smyth AG, Sarri G, Vranic M, Amano Y, Doria D, Guillaume E, Habara H, Heathcote R, Hicks G, Najmudin Z, Nakamura H, Norreys PA, Kar S, Silva LO, Tanaka KA, Vieira J, Borghesi Met al., 2016, Magnetic field generation during intense laser channelling in underdense plasma, Physics of Plasmas, Vol: 23, ISSN: 1089-7674

Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.

Journal article

King M, Gray RJ, Powell HW, MacLellan DA, Gonzalez-Izquierdo B, Stockhausen LC, Hicks GS, Dover NP, Rusby DR, Carroll DC, Padda H, Torres R, Kar S, Clarke RJ, Musgrave IO, Najmudin Z, Borghesi M, Neely D, McKenna Pet 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.

Conference paper

Powell HW, King M, Gray RJ, MacLellan DA, Gonzalez-Izquierdo B, Stockhausen LC, Hicks G, Dover NP, Rusby DR, Carroll DC, Padda H, Torres R, Kar S, Clarke RJ, Musgrave IO, Najmudin Z, Borghesi M, Neely D, McKenna Pet 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.

Journal article

Guillaume E, Humphrey K, Nakamura H, Trines RMGM, Heathcote R, Galimberti M, Amano Y, Doria D, Hicks G, Higson E, Kar S, Sarri G, Skramic M, Swain J, Tang K, Weston J, Zak P, Alves EP, Fonseca RA, Fiuza F, Habara H, Tanaka KA, Bingham R, Borghesi M, Najmudin Z, Silva LO, Norreys PAet al., 2014, Demonstration of laser pulse amplification by stimulated Brillouin scattering, HIGH POWER LASER SCIENCE AND ENGINEERING, Vol: 2, ISSN: 2095-4719

Journal article

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