Publications
74 results found
Dover NP, Ziegler T, Assenbaum S, et al., 2023, Enhanced ion acceleration from transparency-driven foils demonstrated at two ultraintense laser facilities., Light Sci Appl, Vol: 12
Laser-driven ion sources are a rapidly developing technology producing high energy, high peak current beams. Their suitability for applications, such as compact medical accelerators, motivates development of robust acceleration schemes using widely available repetitive ultraintense femtosecond lasers. These applications not only require high beam energy, but also place demanding requirements on the source stability and controllability. This can be seriously affected by the laser temporal contrast, precluding the replication of ion acceleration performance on independent laser systems with otherwise similar parameters. Here, we present the experimental generation of >60 MeV protons and >30 MeV u-1 carbon ions from sub-micrometre thickness Formvar foils irradiated with laser intensities >1021 Wcm2. Ions are accelerated by an extreme localised space charge field ≳30 TVm-1, over a million times higher than used in conventional accelerators. The field is formed by a rapid expulsion of electrons from the target bulk due to relativistically induced transparency, in which relativistic corrections to the refractive index enables laser transmission through normally opaque plasma. We replicate the mechanism on two different laser facilities and show that the optimum target thickness decreases with improved laser contrast due to reduced pre-expansion. Our demonstration that energetic ions can be accelerated by this mechanism at different contrast levels relaxes laser requirements and indicates interaction parameters for realising application-specific beam delivery.
Randolph L, Banjafar M, Preston TR, et al., 2022, Nanoscale subsurface dynamics of solids upon high-intensity femtosecond laser irradiation observed by grazing-incidence x-ray scattering, PHYSICAL REVIEW RESEARCH, Vol: 4
Kon A, Nishiuchi M, Fukuda Y, et al., 2022, Characterization of the plasma mirror system at the J-KAREN-P facility, HIGH POWER LASER SCIENCE AND ENGINEERING, Vol: 10, ISSN: 2095-4719
Kiriyama H, Miyasaka Y, Kon A, et al., 2021, Enhancement of pre-pulse and picosecond pedestal contrast of the petawatt J-KAREN-P laser, High Power Laser Science and Engineering, Vol: 9
We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility. We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stretched pulse and the post-pulse in a chirped-pulse amplification system. We have shown that the time at which the pre-pulse is generated by the post-pulse and its shape are related to the time difference between the stretched main pulse and the post-pulse. With this investigation, we have found and identified the origins of the pre-pulses and have demonstrated the removal of most pre-pulses by eliminating the post-pulse with wedged optics. We have also demonstrated the impact of stretcher optics on the picosecond pedestal.We have realized orders of magnitude enhancement of the pedestal by improving the optical quality of a key component in the stretcher.
Kiriyama H, Miyasaka Y, Sagisaka A, et al., 2021, Improvement of the temporal contrast of pre-pulses by post-pulses in a petawatt J-KAREN-P laser facility
We demonstrate the removal of the pre-pulses based on the exploration of the generation of pre-pulses by post-pulses through the nonlinear process associated with the B-integral in the laser chain of the petawatt facility J-KAREN-P.
Ziegler T, Albach D, Bernert C, et al., 2021, Proton beam quality enhancement by spectral phase control of a PW-class laser system, SCIENTIFIC REPORTS, Vol: 11, ISSN: 2045-2322
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- Citations: 17
Miyatake T, Shiokawa K, Sakaki H, et 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
Kojima S, Miyatake T, Inoue S, et 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.
Kiriyama H, Miyasaka Y, Sagisaka A, et al., 2021, Improvement of the temporal contrast of pre-pulses by post-pulses in a petawatt J-KAREN-P laser facility
We demonstrate the removal of the pre-pulses based on the exploration of the generation of pre-pulses by post-pulses through the nonlinear process associated with the B-integral in the laser chain of the petawatt facility J-KAREN-P.
Dover NP, Nishiuchi M, Sakaki H, et 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
Kondo K, Nishiuchi M, Sakaki H, et 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.
Kiriyama H, Pirozhkov AS, Nishiuchi M, et al., 2020, Petawatt Femtosecond Laser Pulses from Titanium-Doped Sapphire Crystal, CRYSTALS, Vol: 10, ISSN: 2073-4352
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- Citations: 7
Nishiuchi M, Sakaki H, Dover NP, et 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
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- Citations: 3
Kiriyama H, Pirozhkov AS, Nishiuchi M, et 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
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- Citations: 7
Nishiuchi M, Dover NP, Hata M, et 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.
Sakaki H, Yamashita T, Akagi T, et al., 2020, New algorithm using L1 regularization for measuring electron energy spectra, Review of Scientific Instruments, Vol: 91, Pages: 075116-075116, ISSN: 0034-6748
Dover NP, Nishiuchi M, Sakaki H, et 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.
Passalidis S, Ettlinger OC, Hicks GS, et 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
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- Citations: 4
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
Kitagawa A, Fujita T, Hojo S, et 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.
Pikuz SA, Faenov AY, Pikuz TA, et 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.
Kiriyama H, Pirozhkov AS, Nishiuchi M, et al., 2018, High-contrast high-intensity repetitive petawatt laser, OPTICS LETTERS, Vol: 43, Pages: 2595-2598, ISSN: 0146-9592
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- Citations: 86
Alkhimova MA, Faenov AY, Pikuz TA, et 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
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- Citations: 2
Kando M, Pirozhkov AS, Nishiuchi M, et 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.
Kiriyama H, Nishiuchi M, Pirozhkov AS, et 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.
Alkhimova MA, Faenov AY, Skobelev IY, et 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
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- Citations: 10
Kiriyama H, Nishiuchi M, Pirozhkov AS, et 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.
Pirozhkov AS, Fukuda Y, Nishiuchi M, et al., 2017, Approaching the diffraction-limited, bandwidth-limited Petawatt, OPTICS EXPRESS, Vol: 25, Pages: 20486-20501, ISSN: 1094-4087
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- Citations: 68
Dover NP, Nishiuchi M, Sakaki H, et al., 2017, Scintillator-based transverse proton beam profiler for laser-plasma ion sources, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 88, ISSN: 0034-6748
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- Citations: 13
Faenov AY, Alkhimova MA, Pikuz TA, et 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
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- Citations: 5
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