Imperial College London

DrNicholasDover

Faculty of Natural SciencesDepartment of Physics

Marie Skłodowska-Curie Individual Fellow
 
 
 
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Contact

 

+44 (0)20 7594 3791nicholas.dover08 Website

 
 
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Location

 

735Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

68 results found

Miyatake T, Shiokawa K, Sakaki H, Dover NP, Nishiuchi M, Lowe HF, Kondo K, Kon A, Kando M, Kondo K, Watanabe Yet al., 2021, Denoising application for electron spectrometer in laser-driven ion acceleration using a Simulation-supervised Learning based CDAE, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 999, ISSN: 0168-9002

Journal article

Ziegler T, Albach D, Bernert C, Bock S, Brack F-E, Cowan TE, Dover NP, Garten M, Gaus L, Gebhardt R, Goethel I, Helbig U, Irman A, Kiriyama H, Kluge T, Kon A, Kraft S, Kroll F, Loeser M, Metzkes-Ng J, Nishiuchi M, Obst-Huebl L, Pueschel T, Rehwald M, Schlenvoigt H-P, Schramm U, Zeil Ket al., 2021, Proton beam quality enhancement by spectral phase control of a PW-class laser system, SCIENTIFIC REPORTS, Vol: 11, ISSN: 2045-2322

Journal article

Kojima S, Miyatake T, Inoue S, Dinh TH, Hasegawa N, Mori M, Sakaki H, Nishiuchi M, Dover NP, Yamamoto Y, Sasaki T, Ito F, Kondo K, Yamanaka T, Hashida M, Sakabe S, Nishikino M, Kondo Ket al., 2021, Absolute response of a Fuji BAS-TR imaging plate to low-energy protons (<0.2 MeV) and carbon ions (<1 MeV)., Rev Sci Instrum, Vol: 92

This paper reports on the absolute response of a Fuji BAS-TR image plate to relatively low-energy protons (<0.2 MeV) and carbon ions (<1 MeV) accelerated by a 10-TW-class compact high-intensity laser system. A Thomson parabola spectrometer was used to discriminate between different ion species while dispersing the ions according to their kinetic energy. Ion parabolic traces were recorded using an image plate detector overlaid with a slotted CR-39 solid-state detector. The obtained response function for the protons was reasonably extrapolated from previously reported higher-ion-energy response functions. Conversely, the obtained response function for carbon ions was one order of magnitude higher than the value extrapolated from previously reported higher-ion-energy response functions. In a previous study, it was determined that if the stopping range of carbon ions is comparable to or smaller than the grain size of the phosphor, then some ions will provide all their energy to the binder resin rather than the phosphor. As a result, it is believed that the imaging plate response will be reduced. Our results show good agreement with the empirical formula of Lelasseux et al., which does not consider photo-stimulated luminescence (PSL) reduction due to the urethane resin. It was shown that the PSL reduction due to the deactivation of the urethane resin is smaller than that previously predicted.

Journal article

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, Sakaki H, Dover NP, Miyahara T, Shiokawa K, Manabe S, Miyatake T, Kondo K, Kondo K, Iwata Y, Watanabe Y, Kondo Ket al., 2020, Ion species discrimination method by linear energy transfer measurement in Fujifilm BAS-SR imaging plate, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 91, ISSN: 0034-6748

Journal article

Kiriyama H, Pirozhkov AS, Nishiuchi M, Fukuda Y, Sagisaka A, Kon A, Miyasaka Y, Ogura K, Dover NP, Kondo K, Sakaki H, Koga JK, Esirkepov TZ, Huang K, Nakanii N, Kando M, Kondo K, Bock S, Ziegler T, Puschel T, Zeil K, Schramm Uet al., 2020, Petawatt Femtosecond Laser Pulses from Titanium-Doped Sapphire Crystal, CRYSTALS, Vol: 10, ISSN: 2073-4352

Journal article

Kiriyama H, Pirozhkov AS, Nishiuchi M, Fukuda Y, Ogura K, Sagisaka A, Miyasaka Y, Sakaki H, Dover NP, Kondo K, Lowe HF, Kon A, Koga JK, Esirkepov TZ, Nakanii N, Huang K, Kando M, Kondo Ket al., 2020, Status and progress of the J-KAREN-P high intensity laser system at QST, HIGH ENERGY DENSITY PHYSICS, Vol: 36, ISSN: 1574-1818

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

Sakaki H, Yamashita T, Akagi T, Nishiuchi M, Dover NP, Lowe HF, Kondo K, Kon A, Kando M, Tachibana Y, Obata T, Shiokawa K, Miyatake T, Watanabe Yet al., 2020, New algorithm using L1 regularization for measuring electron energy spectra, Review of Scientific Instruments, Vol: 91, Pages: 075116-075116, ISSN: 0034-6748

Journal article

Dover NP, Nishiuchi M, Sakaki H, Kondo K, Alkhimova MA, Faenov AY, Hata M, Iwata N, Kiriyama H, Koga JK, Miyahara T, Pikuz TA, Pirozhkov AS, Sagisaka A, Sentoku Y, Watanabe Y, Kando M, Kondo Ket al., 2020, Effect of small focus on electron heating and proton acceleration in ultrarelativistic laser-solid interactions, Physical Review Letters, Vol: 124, Pages: 084802 – 1-084802 – 7, ISSN: 0031-9007

Acceleration of particles from the interaction of ultraintense laser pulses up to 5×1021  W cm−2 with thin foils is investigated experimentally. The electron beam parameters varied with decreasing spot size, not just laser intensity, resulting in reduced temperatures and divergence. In particular, the temperature saturated due to insufficient acceleration length in the tightly focused spot. These dependencies affected the sheath-accelerated protons, which showed poorer spot-size scaling than widely used scaling laws. It is therefore shown that maximizing laser intensity by using very small foci has reducing returns for some applications.

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

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

Kitagawa A, Fujita T, Hojo S, Katagiri K, Muramatsu M, Sugiura A, Wakui T, Yamada K, Hirano Y, Chiba A, Yoshida KI, Kashiwagi H, Kurashima S, Ohkubo T, Ishii Y, Saitoh Y, Nishiuchi M, Sakaki H, Dover NP, Kondo K, Hiratsuka J, Ichikawa M, Kashiwagi M, Kojima A, Tobari H, Umeda N, Watanabe K, Sakamoto Ket al., 2018, Status of ion sources at the national institutes for quantum and radiological science and technology (QST), ISSN: 0094-243X

The National Institutes for Quantum and Radiological Science and Technology (QST) manages various types of ion sources for research and development in the fields of life sciences, medical and industrial applications, and fusion energy science. The QST is currently developing on electron cyclotron resonance ion sources, negative ion sources (ion sources for fusion and for tandem accelerators), ion sources for radioactive beams, laser ion sources, and miscellaneous ion sources. Its intra- and inter-institutional collaborations make QST a promising platform for future ion source technologies.

Conference paper

Pikuz SA, Faenov AY, Pikuz TA, Skobelev IY, Alkhimova MA, Martynenko AS, Sakaki H, Nishiuchi M, Pirozhkov AS, Sagisaka A, Dover NP, Kondo K, Ogura K, Fukuda Y, Kiriyama H, Kando M, Sentoku Y, Hata M, Zigler A, Nishitani K, Miyahara T, Watanabe Y, Kodama R, Kondo Ket al., 2018, X-ray radiation properties of plasma under interaction of femtosecond laser pulses with ∼ 10<sup>22</sup> W/cm<sup>2</sup> intensities

Study of radiation properties of solid dense plasma irradiated by ultraintense lasers has a great interest both from fundamental physics and different application point of views. Recently upgraded petawatt J-KAREN-P laser together with precise focusing technique delivers 35 fs laser pulses of 1022 W/cm2 intensity into a micron-size focal spot on target. For such unprecedented intensities the application of high-resolution X-ray spectroscopy allows to investigate the ionization mechanisms and to measure the parameters of relativistic plasma from front and rear sides of moderate (Al) and high Z (Ti, Fe,) thin foil targets. Kinetic modeling of the spectra is used to estimate electron plasma density and temperature, demonstrating Te ∼2 keV for Ne ∼5e22 cm-3 in the hottest emission region. Thus, it is experimentally demonstrated for the first time that the laser pulse of over 1e21 W/cm2 intensity is absorbed neither in the solid density plasma nor in a pre-plasma of a common critical density, but in the matter of so called relativistic critical density. It is revealed how even small displacement of the target out of the optimal laser focus, as well the decrease in temporal contrast of the laser pulse, strongly reduce both the intensity of X-ray radiation and degree of plasma ionization. 2D PIC code simulations of femtosecond laser interaction with various materials are provided and compared with experimental results.

Conference paper

Kiriyama H, Pirozhkov AS, Nishiuchi M, Fukuda Y, Ogura K, Sagisaka A, Miyasaka Y, Mori M, Sakaki H, Dover NP, Kondo K, Koga JK, Esirkepov TZ, Kando M, Kondo Ket al., 2018, High-contrast high-intensity repetitive petawatt laser, OPTICS LETTERS, Vol: 43, Pages: 2595-2598, ISSN: 0146-9592

Journal article

Kando M, Pirozhkov AS, Nishiuchi M, Kiriyama H, Kon A, Sakaki H, Fukuda Y, Dover N, Sekiguchi K, Nishitani K, Sagisaka A, Pikuz TA, Faenov AY, Ogura K, Hayashi Y, Kotaki H, Esirkepov TZ, Huang K, Nakanii N, Kondo K, Koga JK, Bulanov SVet al., 2018, Research on Laser Acceleration and Coherent X-Ray Generation Using J-KAREN-P Laser, Pages: 135-142, ISSN: 0930-8989

We present the progress on the upgrade status of the J-KAREN-P, which is a Ti: Sapphire laser aiming at the intensity of 1022 W/cm2 at the repetition rate of 0.1 Hz. The upgrade includes two pilot experiments in order to show the laser performance on target. The first experiment is to generate high-energy ions from thin-foil target. The second experiment is the high-order harmonic at a relativistic intensity. Currently, laser acceleration of protons is being tested and we have obtained 32 MeV protons from a 5-µm stainless steel target irradiated by a 14-J, 30-fs laser pulse. In addition, a joint program toward compact X-ray free-electron laser based on laser electron acceleration is presented briefly and the corresponding J-KAREN-P work is presented.

Conference paper

Alkhimova MA, Faenov AY, Pikuz TA, Skobelev IY, Pikuz SA, Nishiuchi M, Sakaki H, Pirozhkov AS, Sagisaka S, Dover NP, Kondo K, Ogura K, Fukuda Y, Kiriyama H, Esirkepov T, Bulanov SV, Andreev A, Kando M, Zhidkov A, Nishitani K, Miyahara T, Watanabe Y, Kodama R, Kondo Ket al., 2018, X-ray emission from stainless steel foils irradiated by femtosecond petawatt laser pulses, 32nd International Conference on Interaction of Intense Energy Fluxes with Matter (ELBRUS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588

Conference paper

Kiriyama H, Nishiuchi M, Pirozhkov AS, Fukuda Y, Sakaki H, Sagisaka A, Dover NP, Kondo K, Ogura K, Mori M, Miyasaka Y, Koga J, Esirkepov TZ, Hayashi Y, Kotaki H, Huang K, Nakanii N, Bulanov SV, Kando M, Kondo Ket al., 2017, Latest achivements at the J-KAREN-P laser facility at QST, Pages: 1-3

We report on a high-contrast, high-intensity Ti:sapphire chirped-pulse amplification system that incorporates a nonlinear preamplifier based on optical parametric chirpedpulse amplification (OPCPA). Chirped-pulses are amplified to 63 J at 0.1 Hz and compressed down to 30 fs. The temporal contrast is better than 3 x 10-12 on the sub-nanosecond timescale. A peak intensity of 1022 W/cm2 on target is reached by focusing a wavefront corrected 0.3 PW laser beam with an f/1.3 off-axis parabolic mirror.

Conference paper

Alkhimova MA, Faenov AY, Skobelev IY, Pikuz TA, Nishiuchi M, Sakaki H, Pirozhkov AS, Sagisaka A, Dover NP, Kondo K, Ogura K, Fukuda Y, Kiriyama H, Nishitani K, Miyahara T, Watanabe Y, Pikuz SA, Kando M, Kodama R, Kondo Ket al., 2017, High resolution X-ray spectra of stainless steel foils irradiated by femtosecond laser pulses with ultra-relativistic intensities, OPTICS EXPRESS, Vol: 25, Pages: 29501-29511, ISSN: 1094-4087

Journal article

Kiriyama H, Nishiuchi M, Pirozhkov AS, Fukuda Y, Sakaki H, Sagisaka A, Dover N, Kondo K, Nishitani K, Ogura K, Mori M, Miyasaka Y, Koga J, Esirkepov TZ, Hayashi Y, Kotaki H, Huang K, Nakanii N, Bulanov SV, Kando M, Kondo Ket al., 2017, 10<sup>22</sup>W/cm<sup>2</sup>, 0.1 Hz J-KAREN-P laser facility at QST, Pages: 1-2

Broadband-pulses are amplified to 63 J and compressed to 30 fs. A peak intensity of 1022 W/cm2 by focusing a 0.3 PW laser beam with an f/1.4 off-axis parabolic mirror is achievable on target.

Conference paper

Pirozhkov AS, Fukuda Y, Nishiuchi M, Kiriyama H, Sagisaka A, Ogura K, Mori M, Kishimoto M, Sakaki H, Dover NP, Kondo K, Nakanii N, Huang K, Kanasaki M, Kondo K, Kando Met al., 2017, Approaching the diffraction-limited, bandwidth-limited Petawatt, OPTICS EXPRESS, Vol: 25, Pages: 20486-20501, ISSN: 1094-4087

Journal article

Dover NP, Nishiuchi M, Sakaki H, Alkhimova MA, Faenov AY, Fukuda Y, Kiriyama H, Kon A, Kondo K, Nishitani K, Ogura K, Pikuz TA, Pirozhkov AS, Sagisaka A, Kando M, Kondo Ket al., 2017, Scintillator-based transverse proton beam profiler for laser-plasma ion sources, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 88, ISSN: 0034-6748

Journal article

Faenov AY, Alkhimova MA, Pikuz TA, Skobelev IY, Nishiuchi M, Sakaki H, Pirozhkov AS, Sagisaka A, Dover NP, Kondo K, Ogura K, Fukuda Y, Kiriyama H, Andreev A, Nishitani K, Miyahara T, Watanabe Y, Pikuz SA, Kando M, Kodama R, Kondo Ket al., 2017, The effect of laser contrast on generation of highly charged Fe ions by ultra-intense femtosecond laser pulses, APPLIED PHYSICS B-LASERS AND OPTICS, Vol: 123, ISSN: 0946-2171

Journal article

Kiriyama H, Nishiuchi M, Pirozhkov AS, Fukuda Y, Sakaki H, Sagisaka A, Dover NP, Kondo K, Nishitani K, Ogura K, Mori M, Miyasaka Y, Koga J, Esirkepov TZ, Hayashi Y, Kotaki H, Huang K, Nakanii N, Bulanov SV, Kando M, Kondo Ket al., 2017, J-KAREN-P Laser Facility at QST: High Contrast, High Intensity Petawatt OPCPA/Ti:sapphire Hybrid Laser System, Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), Publisher: IEEE

Conference paper

Kiriyama H, Nishiuchi M, Pirozhkov AS, Fukuda Y, Sakaki H, Sagisaka A, Dover NP, Kondo K, Ogura K, Mori M, Miyasaka Y, Koga J, Esirkepov TZ, Hayashi Y, Kotaki H, Huang K, Nakanii N, Bulanov SV, Kando M, Kondo Ket al., 2017, Latest achivements at the J-KAREN-P laser facility at QST, Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR), Publisher: IEEE

Conference paper

Nishiuchi M, Kiriyama H, Sakaki H, Dover NP, Kondo K, Pirozhkov AS, Sagisaka A, Fukuda Y, Nishitani K, Miyahara T, Ogura K, Alkhimova MA, Pikuz TA, Faenov AY, Watanabe Y, Koga J, Bulanov SV, Kando M, Kondo Ket al., 2017, High Contrast High Intensity Petawatt J-KAREN-P Laser facility at QST, Conference on Research Using Extreme Light - Entering New Frontiers with Petawatt-Class Lasers III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X

Conference paper

Nishiuchi M, Kiriyama H, Pirozhkov AS, Sakaki H, Fukuda Y, Dover NP, Nishitani K, Miyahara T, Sagisaka A, Alkhimova MA, Pikuz TA, Faenov AY, Ogura K, Esirkepov TZ, Kondo K, Watanabe Y, Koga JK, Bulanov SV, Kando M, Kondo Ket al., 2017, Ion Acceleration Experiment by High Intensity (10(22) Wcm(-2)), High Contrast (10(-11)) J-KAREN-P Laser System at QST, Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), Publisher: IEEE

Conference paper

Kiriyama H, Nishiuchi M, Pirozhkov AS, Fukuda Y, Sakaki H, Sagisaka A, Dover N, Kondo K, Nishitani K, Ogura K, Mori M, Miyasaka Y, Koga J, Esirkepov TZ, Hayashi Y, Kotaki H, Huang K, Nakanii N, Bulanov SV, Kando M, Kondo Ket al., 2017, 10(22)W/cm(2), 0.1 Hz J-KAREN-P laser facility at QST, Conference on Lasers and Electro-Optics (CLEO), Publisher: IEEE, ISSN: 2160-9020

Conference paper

Chen Y-H, Helle M, Ting A, Gordon D, Dover N, Ettlinger O, Najmudin Z, Polyanskiy M, Pogorelsky I, Babzien Met 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

Conference paper

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