Kansai Institute for Photon Science 　|　High Field Science Research Group

High-field Science Research Group

Leader: KOTAKI Hideyuki

Research Overview

Based on the development of technologies such as the J-KAREN-P laser, which is one of the world's top-class high-intensity lasers, we are conducting research aimed at the cutting edge of academia, including high-intensity physics, including the development of laser acceleration of electrons and ions.
What is high-intensity field science?

A laser beam can be narrowed down to a small size. A laser that shines for a short time, like a camera flash, is called a pulsed laser, and the intensity of the instantaneous light is even greater. Figure 1 shows the focused light intensity and electric field, and (some of) the research topics developed there. We are mainly using lasers to accelerate particles (quantum beam generation), but in high-intensity fields we are trying to open up new areas, ultimately aiming to distort the vacuum (vacuum birefringence) or destroy the vacuum (vacuum destruction). We believe that at such intensities we can approach the mysteries of the universe and the solution of fundamental problems in physics.

​Group members

Research topics

1. Laser-driven quantum beam geneartion

  We are conducting research on the sophistication of generating quantum beam sources such as high-energy ions, electrons, and X-rays by creating high-intensity fields by focusing high-power, ultrashort-pulse lasers to a small size. In ion acceleration, based on the new concept of "quantum scalpel," we are researching the miniaturization of heavy particle accelerators for cancer therapy and developing acceleration methods and instrumentation for heavy particle ions used in advanced science.
   In electron acceleration, research is being conducted to generate quantum beams for compact X-ray free electron lasers and gamma-ray sources.
   A new radiation mechanism called Burst Intensification by Singularity Emitting Radiation (BISER) is being investigated to generate coherent attosecond X-ray pulses, and Relativistic Flying Mirror (RFM) is also being studied. 

2. Ultra-High Field Science  

  We achieved a focused intensity of ~1022 W/cm2, which was the highest intensity in the world in 2017. With this intensity or higher, we explore new phenomena explored theoretically, numerically, and experimentally. 
  Our group has theoretically and numerically demonstrated the radiation of high intensity and short pulse gamma rays (X-rays) by focusing on the radiation attenuation effect. It has now grown to become one of the major themes in high intensity field science and is being studied all over the world.

3. Upgrade and Improvements of J-KAREN-P Laser

In collaboration with Advanced Laser Science Group, we continuously improve and upgrade the performance of J-KAREN-P laser. The J-KAREN-P laser is based on double chirped pulse amplification (CPA) to produce high-contrast, high-intensitiy laser pulses at 0.1 Hz.

Some selected publications (peer-reviewed)

2026年

• Optimized laser wakefield acceleration: Generating stable, high-energy, monoenergetic electron beams and demonstrating extreme-ultraviolet free electron lasers
  Zhan Jin, Masaki Kando, Yan-Jun Gu, Kai Huang, Nobuhiko Nakanii, Izuru Daito, Zhenzhe Lei, Shingo Sato, Hiroaki Sano, Toshiya Muto, Shigeru Yamamoto, and Tomonao Hosokai
  Phys. Rev. Research 8, 013207 (2026). Link

2025年

• Laser focusing equivalence behavior of mass-limited targets in laser particle acceleration
  T. Morita
  Phys. Rev. E 112, 065204 (2025). Link
• Evaluation of imaging plate sensitivities to ion beams
  Y. Hayashi, M. Mori, and H. Kotaki
  Rev. Sci. Inst. 96, 093306 (2025). Link
• Direct measurement of lattice behavior during femtosecond laser-driven shock front formation in copper
  Naoya Egashira, Tomoki Matsuda, Takuo Okuchi, Yusuke Seto, Yusuke Ito, Takahisa Shobu, Nobuhiko Nakanii, Yuichi Inubushi, Tadashi Togashi, Kohei Miyanishi, Tsutomu Mashimo, Tomokazu Sano
  J. Appl. Phys. 137, 105903 (2025). Link
• Toward superstrong fields with a relativistic curved plasma mirror
  Tae Moon Jeong, Sergei V. Bulanov, Rashid Shaisultanov, and Prokopis Hadjisolomou, and Timur Zh. Esirkepov
  Phys. Rev. A 111, 032218 (2025). Link

2024年

• Design of soft x-ray high diffraction efficiency and spectral flux Au/Ni bilayer coated laminar-type diffraction grating for objective soft x-ray flat-field spectrograph in a region of 250–550 eV
  M. Koike, T. Hatano, A. S. Pirozhkov, T. Murano, Y. Oue, S. Koshiya, T. Kakio, K. Kondo, and M. Terauchi
  Rev. Sci. Instrum. 95, 123102 (2024). Link
• Measuring the sensitivity of imaging plates to keV carbon ions
  Yukio Hayashi, Michiaki Mori, Hideyuki Kotaki, Shinobu Onoda, Keisuke Yamada, and Masaki Kando
  Rev. Sci. Instrum. 95, 123309 (2024). Link
• Evolution of a laser wake cavity in a MCF plasma
  Andreas Bierwage, Timur Zh. Esirkepov, James K. Koga, Alexander S. Pirozhkov, Nobuyuki Aiba, Kai Huang, Masasaki Kando, Hiromitsu Kiriyama, Akinobu Matsuyama, Kouji Shinohara, Masatoshi Yagi, and Gunsu S. Yun
  Scientific Reports 14, 27853 (2024). Link
• In-vacuum post-compression of optical probe pulse for relativistic plasma diagnostics
  S. Lorenz, G. M. Grittani, K. Kondo, A. Kon, Y.-K. Liu, A. Sagisaka, K. Ogura, N. Nakanii, K. Huang, A. Bierwage, S. Namba, H. Ohiro, T. A. Pikuz, J. K. Koga, P. Chen, H. Kiriyama, M. Kando, T. Zh. Esirkepov, S. V. Bulanov and A. S. Pirozhkov
  High Power Laser Science and Engineering journal, 12, e53 (2024). Link
• Performance of laser ion source LION operated at Brookhaven National Laboratory
  K. Takahashi, M. Okamura, T. Kanesue, S. Ikeda, K. Kondo, M. Sekine and T. Karino
  J. Phys.: Conf. Ser. 2743, 012096 (2024). Link
• Experimental realization of near-critical-density laser wakefield acceleration: Efficient pointing 100-keV-class electron beam generation by microcapillary targets
  Michiaki Mori, Ernesto Barraza-Valdez, Hideyuki Kotaki, Yukio Hayashi, Masaki Kando, Kiminori Kondo, Tetsuya Kawachi, Donna Strickland, Toshiki Tajima
  AIP Advances 14, 035153 (2024). Link

2023

• Controllable electron self-injection in laser wakefield acceleration with symmetric gas-jet profile
  Zhenzhe Lei,  Zhan Jin,  Alexei Zhidkov,  Naveen Pathak,  Yoshio Mizuta,  Kai Huang, Nobuhiki Nakanii,  Izuru Daito,  Masaki Kando,  Tomonao Hosokai
  Progress of Theoretical and Experimental Physics, 2023 (3), 033J01 (2023).
  https://doi.org/10.35848/1882-0786/ac5237
• Precise pointing control of high-energy electron beam from laser wakefield acceleration using an aperture
  Nobuhiko Nakanii, Kai Huang, Kotaro Kondo, Hiromitsu Kiriyama and Masaki Kando
  Appl. Phys. Express 16, 026001 (2023).
  https://doi.org/10.35848/1882-0786/acb892
• Enhanced ion acceleration from transparency-driven foils demonstrated at two ultraintense laser facilities
  Nicholas P. Dover, Tim Ziegler, Stefan Assenbaum, Constantin Bernert, Stefan Bock, Florian-Emanuel Brack, Thomas E. Cowan, Emma J. Ditter, Marco Garten, Lennart Gaus, Ilja Goethel, George S. Hicks, Hiromitsu Kiriyama, Thomas Kluge, James K. Koga, Akira Kon, Kotaro Kondo, Stephan Kraft, Florian Kroll, Hazel F. Lowe, Josefine Metzkes-Ng, Tatsuhiko Miyatake, Zulfikar Najmudin, Thomas Püschel, Martin Rehwald, Marvin Reimold, Hironao Sakaki, Hans-Peter Schlenvoigt, Keiichiro Shiokawa, Marvin E. P. Umlandt, Ulrich Schramm, Karl Zeil & Mamiko Nishiuchi
  Light: Science & Applications 12, 71 (2023).
  https://doi.org/10.1038/s41377-023-01083-9
• Spectral-temporal measurement capabilities of third-order correlators
  Stefan Bock, Thomas Oksenhendler, Thomas Püschel, René Gebhardt, Uwe Helbig, Richard Pausch, Tim Ziegler, Constantin Bernert, Karl Zeil, Arie Irman, Toma Toncian, Hiromitsu Kiriyama, Mamiko Nishiuchi, Akira Kon, and Ulrich Schramm
  Optics Express, 31 (6), 9923-9934 (2023). Link

2022

• Experimental demonstration of 7-femtosecond electron timing fluctuation in laser wakefield acceleration
  Kai Huang, Zhan Jin, Nobuhiko Nakanii, Tomonao Hosokai, Masaki Kando
  Appl. Phys. Exp. 15, 036001 (2022).
  https://doi.org/10.35848/1882-0786/ac5237
• Prospects of Relativistic Flying Mirrors for Ultra-High-Field Science
  Masaki Kando, Alexander S. Pirozhkov, James K. Koga, Timur Zh. Esirkepov and Sergei V. Bulanov
  Photonics 9, 862 (2022) [Review].
  https://doi.org/10.3390/photonics9110862
• Characteristics of laminar ion beams accelerated via a few-joule laser pulse
  Toshimasa Morita
  Phys. Review Research 4, 043020 (2022).
  https://doi.org/10.1103/PhysRevResearch.4.043020
• Enhanced diagnostics of radiating relativistic singularities and BISER by nonlinear post-compression of optical probe pulse
  A.V. Kotov, T.Zh. Esirkepov, A.A. Soloviev, A. Sagisaka, K. Ogura, A. Bierwage, M. Kando, H. Kiriyama, M.V. Starodubtsev, E.A. Khazanov, S.Yu. Mironov and A.S. Pirozhkov
  Journal of Instrumentation 17, P07035 (2022).
  https://doi.org/10.1088/1748-0221/17/07/P07035
• Nanoscale subsurface dynamics of solids upon high-intensity femtosecond laser irradiation observed by grazing-incidence x-ray scattering
  Lisa Randolph, Mohammadreza Banjafar, Thomas R. Preston, Toshinori Yabuuchi, Mikako Makita, Nicholas P. Dover, Christian Rödel , Sebastian Göde, Yuichi Inubushi, Gerhard Jakob, Johannes Kaa, Akira Kon, James K. Koga, Dmitriy Ksenzov, Takeshi Matsuoka, Mamiko Nishiuchi, Michael Paulus, Frederic Schon, Keiichi Sueda, Yasuhiko Sentoku, Tadashi Togashi, Michael Bussmann, Thomas E. Cowan, Mathias Kläui, Carsten Fortmann-Grote, Lingen Huang, Adrian P. Mancuso, Thomas Kluge, Christian Gutt, and Motoaki Nakatsutsumi
  Phys. Rev. Res. 4, 033038 (2022).
  https://doi.org/10.1103/PhysRevResearch.4.033038
• Characterization of the plasma mirror system at the J-KAREN-P facility
  Akira Kon, Mamiko Nishiuchi, Yuji Fukuda, Kotaro Kondo, Koichi Ogura, Akito Sagisaka, Yasuhiro Miyasaka, Nicholas P. Dover, Masaki Kando, Alexander S. Pirozhkov, Izuru Daito, Liu Chang, Il Woo Choi, Chang Hee Nam, Tim Ziegler, Hans-Peter Schlenvoigt, Karl Zeil, Ulrich Schramm, and Hiromitsu Kiriyama
  High Power Laser Science and Engineering, 10, e25 (2022).
  https://doi.org/10.1017/hpl.2022.15
• Construction of a Magnetic Bottle Electron Spectrometer for Electron Energy Measurement in BISER X-Rays and Xe Interaction
  Hikari OHIRO, Alexander S. PIROZHKOV, Koichi OGURA, Akito SAGISAKA, Tatiana A. PIKUZ, Kai HUANG, Masaki KANDO, Kotaro YAMASAKI and Shinichi NAMBA
  Plasma and Fusion Research, 17, 2406020 (2022).
  https://doi.org/10.1585/pfr.17.2406020
• Facilities in Asia for future accelerator development
  M. Kando, T. Hosokai, K. Y. Kim, and C. Tang
  Journal of Instrumentation, 17 T06001 (2022) [Technical Report]
  https://doi.org/10.1088/1748-0221/17/06/T06001

2021

• Relativistic flying laser focus by a laser-produced parabolic plasma mirror
  Tae Moon Jeong, Sergei V. Bulanov, Petr Valenta, Georg Korn, Timur Zh. Esirkepov, James K. Koga, Alexander S. Pirozhkov, Masaki Kando, and Stepan S. Bulanov
  Phys. Rev. A 104, 053533 (2021). https://doi.org/10.1103/PhysRevA.104.053533
• Gamma factory searches for extremely weakly interacting particles​s
  Sreemanti Chakraborti, Jonathan L. Feng, James K. Koga, and Mauro Valli, 
  Phys. Rev. D 104, 055023 (2021). https://doi.org/10.1103/PhysRevD.104.055023
• Denoising application for electron spectrometer in laser-driven ion acceleration using a Simulation-supervised Learning based CDAE 
  Tatsuhiko Miyatake, Keiichiro Shiokawa, Hironao Sakaki, Nicholas P. Dover, Mamiko Nishiuchi, Hazel F. Lowe, Kotaro Kondo, Akira Kon, Masaki Kando, Kiminori Kondob, Yukinobu Watanabe
  Nucl. Instru. Meth. A 999, 165227 (2021). https://doi.org/10.1016/j.nima.2021.165227
• ​Proton beam quality enhancement by spectral phase control of a PW-class laser system
  T. Ziegler, D. Albach, C. Bernert, S. Bock, F.-E. Brack, T. E. Cowan, N. P. Dover, M. Garten, L. Gaus, R. Gebhardt, I. Goethel, U. Helbig, A. Irman, H. Kiriyama, T. Kluge, A. Kon, S. Kraft, F. Kroll, M. Koeser, J. Metzkes-Ng, M. Nishiuchi, L. Obst-Huebl, T. Püschel, M. Rehwald, H.-P. Schlenvoigt, U. Schramm, & K. Zeil
  Scientific Reports 11, 7338 (2021). https://www.nature.com/articles/s41598-021-86547-x 

​2020

• Characterization of Accumulated B-Integral of Regenerative Amplifier Based CPA Systems
  S. Bock, F. M. Herrmann, T. Püschel, U. Helbig, R. Gebhardt, J. J. Lötfering, R. Pausch, K. Zeil, T. Ziegler, A. Irman, T. Oksenhendler, A. Kon, M. Nishuishi, H. Kiriyama, K. Kondo, T. Toncian, and U. Schramm, Crystals 10, 1 (2020). https://doi.org/10.3390/cryst10090847
• Relativistic Flying Forcibly Oscillating Reflective Diffraction Grating
  Jie Mu, T. Zh. Esirkepov, Petr Valenta, Yanjun Gu, Tae Moon Jeong, Alexander S. Pirozhkov, James K. Koga, Masaki Kando, Georg Korn, and Sergei V. Bulanov, Phys. Rev. E, 102, 053202 (2020). https://doi.org/10.1103/PhysRevE.102.053202
• Electron-Positron Pair Creation in the Electric Fields Generated by Micro-bubble Implosions 
  James K. Koga, Masakatsu Murakami, Alexey V. Arefiev, Yoshihide Nakamiya, Stepan S. Bulanov, Sergei V. Bulanov, Physics Letters A　384, 126854 (2020). 
  https://doi.org/10.1016/j.physleta.2020.126854
• Ion species discrimination method by linear energy transfer measurement in Fujifilm BAS-SR Imaging Plate
  M. Nishiuchi, H. Sakaki, N. P. Dover, T. Miyahara, K. Shiokawa, S. Manabe, T. Miyatake, Ko. Kondo, Ke. Kondo, Y. Iwata, Y. Watanabe, and Ki. Kondo , Rev. Sci. Instru. 91, 093305 (2020). 
  https://doi.org/10.1063/5.0016515
• High intensity laser driven oxygen source from CW laser heated Ti tape targets
  Kotaro Kondo, Mamiko Nishiuchi, Hironao Sakaki, Nicholas P. Dover, Hazel F. Lowe, Takumi Miyahara, Yukinobu Watanabe, Tim Ziegler, Karl Zeil, Ulrich Schramm, Emma J. Ditter, George S. Hicks, Oliver C. Ettlinger, Zulfikar Najmudin, Hiromitsu Kiriyama, Masaki Kando and Kiminori Kondo, Crystals 10, 837 (2020). 
  https://doi.org/10.3390/cryst10090837
• Topological investigation of laser ion acceleration
  T. Morita, Plasma Phys. Control. Fusion 62, 105003 (2020).
  https://dx.doi.org/10.1088/1361-6587/aba766
• New algorithm using L1 regularization for measuring electron energy spectra
  Hironao Sakaki, Tomohiro Yamashita, Takashi Akagi, Mamiko Nishiuchi, Nicholas P. Dover, Hazel F. Lowe, Kotaro Kondo, Akira Kon, Masaki Kando, Yasuhiko Tachibana, Takayuki Obata, Keiichiro Shiokawa, Tatsuhiko Miyatake, and Yukinobu Watanabe, Review of Scientific Instruments 91, 075116 (2020).
  https://doi.org/10.1063/1.5144897
• Single-shot electro-optic sampling on the temporal structure of laser wakefield accelerated electrons
  Kai Huang, Hideyuki Kotaki, Michiaki Mori, Yukio Hayashi, Nobuhiko Nakanii and Masaki Kando, Crystals 2020, 10(8), 640 (2020).
  https://doi.org/10.3390/cryst10080640
• Single-shot measurement of post-pulse-generated pre-pulse
  Akira Kon, Mamiko Nishiuchi, Hiromitsu Kiriyama, Masaki Kando, Stefan Bock, Tim Ziegler, Thomas Pueschel, Karl Zeil, Ulrich Schramm and Kiminori Kondo, Crystals, 10(8), 657 (2020).
  https://doi.org/10.3390/cryst10080657
• Dynamics of laser-driven heavy-ion acceleration clarified by ion charge states
  M. Nishiuchi, N. P. Dover, M. Hata, H. Sakaki, Ko. Kondo, H. F. Lowe, T. Miyahara, H. Kiriyama, J. K. Koga, N. Iwata, M. A. Alkhimova, A. S. Pirozhkov, A. Ya. Faenov, T. A. Pikuz, A. Sagisaka, Y. Watanabe, M. Kando, K. Kondo, E. J. Ditter, O. C. Ettlinger, G. S. Hicks, Z. Najmudin, T. Ziegler, K. Zeil, U. Schramm and Y. Sentoku, Phys. Rev. Research 2, 033081 (2020).
  https://doi.org/10.1103/PhysRevResearch.2.033081
• Status and progress of the J-KAREN-P high intensity laser system at QST
  Hiromitsu Kiriyama, Alexander, S. Pirozhkov, Mamiko Nishiuchi, Yuji Fukuda, Koichi Ogura, Akito Sagisaka, Yasuhiro Miyasaka, Hironao Sakaki, Nicholas P. Dover, Kotaro Kondo, Hazel F. Lowe, Akira Kon, James K. Koga, Timur Zh. Esirkepov, Nobuhiko Nakanii, Kai Huang, Masaki Kando, Kiminori Kondo, High Energy Density Physics 36, 100771 (2020). https://doi.org/10.1016/j.hedp.2020.100771 
• Observation of Burst Intensification by Singularity Emitting Radiation generated from relativistic plasma with a high-intensity laser
  A. Sagisaka, K. Ogura, T. Zh. Esirkepov, D. Neely, T. A. Pikuz, J. K. Koga, Y. Fukuda, H. Kotaki, Y. Hayashi, B. Gonzalez-Izquierdo, K. Huang, S. V. Bulanov, H. Kiriyama, K. Kondo, T. Kawachi, M. Kando, A. S. Pirozhkov, High Energy Density Physics, 36, 100751 (2020). https://doi.org/10.1016/j.hedp.2020.100751
• Light scattering by 4π-spherically-focused ultra-strong light field
  Tae Moon Jeong, Sergey Bulanov, Pavel V. Sasorov, Georg Korn, James Kevin Koga, Stepan S. Bulanov, Phys. Rev. A 28 (9), pp. 13991–14006 (2020).https://doi.org/10.1364/OE.387654
• Recoil effects on reflection from relativistic mirrors in laser plasmas
  P. Valenta, T. Zh. Esirkepov, J. K. Koga, A. S. Pirozhkov, M. Kando, T. Kawachi, Y.-K. Liu, P. Fang, P. Chen, J. Mu, G. Korn, O. Klimo, and S. V. Bulanov, Physics of Plasmas 27, 032109 (2020). https://doi.org/10.1063/1.5142084
• Optical probing of relativistic plasma singularities
  Timur Zh. Esirkepov, Jie Mu, Yanjun Gu, Tae Moon Jeong, Petr Valenta, Ondrej Klimo, James K. Koga, Masaki Kando, David Neely, Georg Korn, Sergei V. Bulanov, and Alexander S. Pirozhkov, Physics of Plasmas 27, 052103 (2020). https://doi.org/10.1063/5.0004525
• Characterization of ionization injection in gas mixtures irradiated by subpetawatt class laser pulses
  A. Zhidkov, N. Pathak, J. K. Koga, K. Huang, M. Kando, and T. Hosokai, Phys. Rev. Research 2, 013216 (2020). https://doi.org/10.1103/PhysRevResearch.2.013216
• Effect of Small Focus on Electron Heating and Proton Acceleration in Ultrarelativistic Laser-Solid Interactions
  N. P. Dover, M. Nishiuchi, H. Sakaki, Ko. Kondo, M. A. Alkhimova, A. Ya. Faenov, M. Hata, N. Iwata, H. Kiriyama, J. K. Koga, T. Miyahara, T. A. Pikuz, A. S. Pirozhkov, A. Sagisaka, Y. Sentoku, Y. Watanabe, M. Kando, and K. Kondo, Phys. Rev. Lett. 124, 084802 (2020). https://doi.org/10.1103/PhysRevLett.124.084802

   2019

• Variation in electron emission time in weakly nonlinear laser wakefield acceleration
  K. Huang, H. Kotaki, M. Mori, T. Esirkepov, J. K. Koga, Y. Hayashi, N. Nakanii, S. V. Bulanov, and M. Kando, Phys. Rev. Accel. Beams 22, 121301 (2019). https://doi.org/10.1103/PhysRevAccelBeams.22.121301
• Multiple colliding laser pulses as a basis for studying high-field high-energy physics
  J. Magnusson, A. Gonoskov, M. Marklund, T. Zh. Esirkepov, J. K. Koga, K. Kondo, M. Kando, S. V. Bulanov, G. Korn, C. G. R. Geddes, C. B. Schroeder, E. Esarey, and S. S. Bulanov, Phys. Rev. A 100, 063404 (2019). https://doi.org/10.1103/PhysRevA.100.063404
• The Utility of Applying Various Image Preprocessing Strategies to Reduce the Ambiguity in Deep Learning-based Clinical Image Diagnosis
  Yasuhiko Tachibana, Takayuki Obata, Jeff Kershaw, Hironao Sakaki, Takuya Urushihata, Tokuhiko Omatsu, Riwa Kishimoto, Tatsuya Higashi, Magnetic Resonance in Medical Sciences (2019). https://doi.org/10.2463/mrms.mp.2019-0021
• Probing and possible application of the QED vacuum with micro-bubble implosions induced by ultra-intense laser pulses
  James K. Koga, Masakatsu Murakami, Alexey V. Arefiev, Yoshihide Nakamiya, Matter and Radiation at Extremes, 4 (3), 034401 (2019).
  https://aip.scitation.org/doi/10.1063/1.5086933
• Relativistic proton emission from ultrahigh-energy-density nanosphere generated by microbubble implosion
  M. Murakami, A. V. Arefiev, M. A. Zosa, J. K. Koga, Y. Nakamiya, Physics of Plasmas 26, 043112 (2019). https://doi.org/10.1063/1.5093043

   2018

• High-contrast high-intensity repetitive petawatt laser
  Hiromitsu Kiriyama, Alexander S. Pirozhkov, Mamiko Nishiuchi, Yuji Fukuda, Koichi Ogura, Akito Sagisaka, Yasuhiro Miyasaka, Michiaki Mori, Hironao Sakaki, Nicholas P. Dover, Kotaro Kondo, James K. Koga, Timur Zh. Esirkepov, Masaki Kando, and Kiminori Kondo, Optics Letters 43 (11), pp. 2595-2598 (2018). https://doi.org/10.1364/OL.43.002595
• Relativistically upshifted higher harmonic generation via relativistic flying mirrors
  James. K Koga, Sergei V. Bulanov, Timur Zh. Esirkepov, Masaki Kando, Stepan S. Bulanov and Alexander S. Pirozhkov,  Plasma Physics and Controlled Fusion 60 (7), 074007 (2018). https://doi.org/10.1088/1361-6587/aac068
  Corrigendum: Relativistically upshifted higher harmonic generation via relativistic flying mirrors (2018 Plasma Phys. Control. Fusion 60 074007)
  https://doi.org/10.1088/1361-6587/aad012
• Coherent, Short-Pulse X-ray Generation via Relativistic Flying Mirrors
  Masaki Kando, Timur Zh. Esirkepov, James K. Koga, Alexander S. Pirozhkov and Sergei V. Bulanov, Quantum Beam Science 2 (2), 9 (2018) [Review]; https://doi.org/10.3390/qubs2020009
• On annihilation of the relativistic electron vortex pair in collisionless plasmas
  K. V. Lezhnin, F. F. Kamenets, T. Zh. Esirkepov and S. V. Bulanov, Journal of Plasma Physics 84 (6), 905840610 (2018); https://doi.org/10.1017/S0022377818001162

   2017

• Possible Precise Measurement of Delbrück Scattering Using Polarized Photon Beams
  James K. Koga and Takehito Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).
  https://doi.org/10.1103/PhysRevLett.118.204801
• High resolution X-ray spectra of stainless steel foils irradiated by femtosecond laser pulses with ultra-relativistic intensities
  M. A. Alkhimova, A. Ya. Faenov, I. Yu. Skobelev, T. A. Pikuz, M. Nishiuchi, H. Sakaki, A. S. Pirozhkov, A. Sagisaka, N. P. Dover, Ko. Kondo, K. Ogura, Y. Fukuda, H. Kiriyama, K. Nishitani, T. Miyahara, Y. Watanabe, S. A. Pikuz, M. Kando, R. Kodama, and K. Kondo, Optics Express 25 (23), pp. 29501-29511 (2017);
  https://doi.org/10.1364/OE.25.029501

Collaborations

• The Institute of Scientific and Industrial Research, Osaka University, Japan
• Institute of Laser Engineering, Osaka University, Japan
• Helmholtz Zentrum Dresden Rossendorf (HZDR), Germany
• ELI Beamlines, Czech Republic
• ELI Nuclear Physics, Romania