Koga, J. K.; 森 道昭; 小瀧 秀行; Bulanov, S. V.; Esirkepov, T. Z.; 桐山 博光; 神門 正城
AIP Conference Proceedings 1721, p.050003_1 - 050003_8, 2016/03
In this talk I will discuss our participation in the ImPACT project, which has as one of its goals, the development an ultra-compact electron accelerator using lasers ( 1 GeV, 10 m) and generation of an X-ray beam from the accelerated electrons. Within this I will discuss our investigation into electron beam monitoring and control. Since laser accelerated electrons will be used for X-ray beam generation combined with an undulator, I will present investigation into the possibilities of the improvement of electron beam emittance through cooling.
Oks, E.*; Dalimier, E.*; Faenov, A.*; Pikuz, T.*; 福田 祐仁; Andreev, A.*; Koga, J. K.; 榊 泰直; 小瀧 秀行; Pirozhkov, A. S.; et al.
Optics Express (Internet), 23(25), p.31991 - 32005, 2015/12
Esirkepov, T. Z.; Bulanov, S. S.*; Koga, J. K.; 神門 正城; 近藤 公伯; Rosanov, N. N.*; Korn, G.*; Bulanov, S. V.
Physics Letters A, 379(36), p.2044 - 2054, 2015/09
In an electromagnetic standing wave formed by two super-intense colliding laser pulses, radiation reaction totally modifies the electron motion. The quantum corrections to the electron motion and the radiation reaction force can be independently small or large, depending on the laser intensity and wavelength, thus dividing the parameter space into 4 domains. The electron motion evolves to limit cycles and strange attractors when radiation reaction dominates. This creates a new framework for high energy physics experiments on the interaction of energetic charged particle beams and colliding super-intense laser pulses.
小瀧 秀行; 川瀬 啓悟*; 林 由紀雄; 森 道昭; 神門 正城; Koga, J. K.; Bulanov, S. V.
Journal of the Physical Society of Japan, 84(7), p.074501_1 - 074501_5, 2015/07
Laser wakefield acceleration has the possibility to generate an ultrashort electron beam of the order of femtoseconds or less. Generation of ultrashort pulses is a key to exploring the dynamical behavior of matter on ever-shorter timescales. We found that the profile of the electron beam was manipulated by rotating the laser polarization. The electron beam is in the laser field, which oscillates the electron beam. From electron oscillations in the image of the electron energy distribution, the electron beam pulse width is estimated to be 1.7 fs (rms). The peak current is 10 kA.
Bulanov, S. V.; 余語 覚文*; Esirkepov, T. Z.; Koga, J. K.; Bulanov, S. S.*; 近藤 公伯; 神門 正城
Physics of Plasmas, 22(6), p.063108_1 - 063108_11, 2015/06
A nonlinear oscillator with an abruptly inhomogeneous restoring force driven by an uniform oscillating force exhibits stochastic properties under specific resonance conditions. This behaviorelucidates the elementary mechanism of the electron energization in the strong electromagnetic waveinteraction with thin targets.
Bulanov, S. V.; Esirkepov, T. Z.; Koga, J. K.; Pirozhkov, A. S.; 近藤 公伯; 神門 正城
Research Using Extreme Light; Entering New Frontiers with Petawatt-Class Lasers II (Proceedings of SPIE, Vol.9515), p.95150C_1 - 95150C_13, 2015/06
High-order harmonic generation of high intensity ultra-short laser pulses by means of laser produced plasmas are discussed. Since with plasma targets there is no limitation on applicable laser intensity the generated harmonics can be substantially intense. Recent results of experiments and computer simulations on the high-order harmonic generation are briefly reviewed. Main attention is paid to the analysis of basic mechanisms of high-order harmonic generation from overdense and underdense plasma targets irradiated by relativistically intense laser pulses.
桐山 博光; 森 道昭; Pirozhkov, A. S.; 小倉 浩一; 匂坂 明人; 今 亮; Esirkepov, T. Z.; 林 由紀雄; 小瀧 秀行; 金崎 真聡*; et al.
IEEE Journal of Selected Topics in Quantum Electronics, 21(1), p.1601118_1 - 1601118_18, 2015/01
Bulanov, S. V.; Esirkepov, T. Z.; 神門 正城; Koga, J. K.; 近藤 公伯; Korn, G.*
Plasma Physics Reports, 41(1), p.1 - 51, 2015/01
We discuss the ways towards modelling of astrophysical processes and extreme field regimes with superpower lasers. This will enable modelling under terrestrial laboratory conditions the processes in astrophysical objects and paves the way to experimental verifications using ultra intense lasers.
Pirozhkov, A. S.; 神門 正城; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; 河内 哲哉; 匂坂 明人; Koga, J. K.; 森 道昭; 川瀬 啓悟*; et al.
RAL-TR-2015-025, P. 22, 2015/00
We provide a description of experiments performed with the J-KAREN and Astra Gemini lasers where we discovered a new regime of relativistic high-order harmonic generation by multi-terawatt femtosecond lasers in gas targets. The results were explained using particle-in-cell simulations and catastrophe theory. Our work paves the way towards a bright coherent X-ray source based on compact lasers and accessible, repetitive, and debris-free gas jet targets. Such a source will be crucial for fundamental research and numerous applications requiring pumping, probing, imaging of microscopic objects and for attosecond science.
Pirozhkov, A. S.; 神門 正城; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; 河内 哲哉; 匂坂 明人; et al.
New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09
We present a detailed description of our discovery of a new regime of high-order harmonic generation, including experimental data, simulations, and description of new harmonic generation mechanism. The harmonics are generated by multi-terawatt relativistic-irradiance ( 10 W/cm) femtosecond ( 30-50 fs) lasers focused to gas jet targets. According to our model, the harmonics are produced by sharp, structurally stable, oscillating electron spikes at the joint of boundaries of wake and bow waves excited by the laser pulse.
Esirkepov, T. Z.; Koga, J. K.; 砂原 淳*; 守田 利昌; 錦野 将元; 影山 慶*; 長友 英夫*; 西原 功修; 匂坂 明人; 小瀧 秀行; et al.
Nuclear Instruments and Methods in Physics Research A, 745, p.150 - 163, 2014/05
When a finite contrast petawatt laser pulse irradiates a micron-thick foil, a prepulse creates a preplasma, where an ultrashort relativistically strong portion of the laser pulse acquires higher intensity due to relativistic self-focusing and undergoes fast depletion transferring energy to fast electrons. If the preplasma thickness is optimal, the main pulse can reach the target generating fast ions more efficiently than an ideal, infinite contrast, laser pulse. The optimal conditions for hundreds of MeV ion acceleration are found with accompanying effects important for diagnostics, including high-order harmonics generation.
Zhidkov, A.*; 益田 伸一*; Bulanov, S. S.*; Koga, J. K.; 細貝 知直*; 児玉 了祐*
Physical Review Special Topics; Accelerators and Beams, 17(5), p.054001_1 - 054001_7, 2014/05
Nonlinear cascade scattering of intense tightly focused laser pulses by relativistic electrons is studied numerically including the classical radiation damping. The electron energy loss, along with its side scattering by the ponderomotive force makes the scattering in the vicinity of high laser field nearly impossible at high electron energies. The use of a second co-propagating laser pulse as a booster is shown to solve this problem.
瀬戸 慧大*; Zhang, S.*; Koga, J. K.; 長友 英夫*; 中井 光男*; 三間 圀興*
Progress of Theoretical and Experimental Physics (Internet), 2014(4), p.043A01_1 - 043A01_10, 2014/04
From the development of the electron theory by H. A. Lorentz in 1906, many authors have tried to reformulate this model. P. A. M. Dirac derived the relativistic-classical electron model in 1938, which is now called the Lorentz-Abraham-Dirac model. But this model has the big difficulty of the run-away solution. Recently, this equation has become important for ultra-intense laser-electron (plasma) interactions. For simulations in this research field, it is desirable to stabilize this model of the radiation reaction. In this paper, we will discuss this ability for radiation reaction with the inclusion of vacuum polarization.
Koga, J. K.; 早川 岳人
JPS Conference Proceedings (Internet), 1, p.016008_1 - 016008_4, 2014/03
We will present an outline of how to calculate the Delbrck scattering cross section using the LoopTools package of routines designed for calculations of the loop integrals resulting from Feynman diagrams, which are involved in the Delbrck scattering, and some preliminary calculations.
瀬戸 慧大*; Koga, J. K.; Zhang, S.*
レーザー研究, 42(2), p.174 - 178, 2014/02
Radiation reaction is one of the remaining big problems in theoretical physics. When an electron has high energy, radiation from this electron might become significant. Since this regime involves laser intensities over W/cm, we need to consider it under next generation laser-electron interactions. Moreover, this radiation reaction is studied as an electron model in classical physics. Therefore, the research of ultrahigh intense laser-high energy electron interactions has the potential to take us to the center and essence of physics. However, the Lorentz-Abraham-Dirac theory which is the standard model of radiation reaction, has a difficulty of the run-away solution. In this paper, the history of the researches of radiation reaction, our recent studies and the experimental design of this process will be presented.
瀬戸 慧大*; 長友 英夫*; Koga, J. K.; 田口 俊弘*; 三間 圀興*
EPJ Web of Conferences (Internet), 59, p.17020_1 - 17020_4, 2013/11
When the laser intensity becomes higher than 10 W/cm, the motion of the electron becomes relativistic with the large radiation. This radiation energy loss transferred to the kinetic energy loss of the electron, is treated as an external force, the "radiation reaction force". We show the new equation of motion with radiation reaction and the simulation method and result of single electron system or dual electrons system with Linard-Wiechert field interaction.
Bulanov, S. V.; Esirkepov, T. Z.; 神門 正城; Koga, J. K.; 細貝 知直*; Zhidkov, A.*; 児玉 了祐*
Physics of Plasmas, 20(8), p.083113_1 - 083113_10, 2013/08
Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are amodel for the electron fluid collapse at the axis behind the ultrashort relativisically intense laserpulse exciting the plasma wake wave. We present the analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents from closing the cavity formed behind the laserpulse.
Lobet, M.*; 神門 正城; Koga, J. K.; Esirkepov, T. Z.; 中村 龍史; Pirozhkov, A. S.; Bulanov, S. V.
Physics Letters A, 377, p.1114 - 1118, 2013/06
Bulanov, S. V.; Esirkepov, T. Z.; 神門 正城; Koga, J. K.; 中村 龍史; Bulanov, S. S.*; Zhidkov, A.*; 加藤 義章; Korn, G.*
High-Power, High-Energy, and High-Intensity Laser Technology; and Research Using Extreme Light: Entering New Frontiers with Petawatt-Class Lasers (Proceedings of SPIE, Vol.8780), p.878015_1 - 878015_15, 2013/05
We discuss the key important regimes of electromagnetic field interaction with charged particles. The main attention is paid to nonlinear Thomson/Compton scattering regime with the radiation friction and quantum electrodynamics effects taking into account. This process opens a channel of high efficiency electromagnetic energy conversion into the hard electromagnetic radiation in the form of ultra short high power ray flashes.
瀬戸 慧大*; 長友 英夫*; Koga, J. K.; 三間 圀興*
Progress of Theoretical and Experimental Physics (Internet), 2013(5), p.053A01_1 - 053A01_10, 2013/05
The intensity of ultra-short pulse lasers has reached W/cm owing to the advancements in laser technology. The large radiation from the electron behaves something like resistance in this ultrarelativistic laser-electron interaction. This effect is called the "radiation reaction". The equation of motion with the radiation reaction is known as the Lorentz-Abraham-Dirac equation; however, this equation does not incorporate the spin property. In laser plasmas, classical physics descriptions are preferred for simulations. This paper discusses how to describe the radiation reaction of a spinning relativistic electron in classical dynamics.