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Anatoly Faenov,
Tatiana Pikuz,
Yuji Fukuda,
Masaki Kando, Hideyuki Kotaki,
Takayuki Homma,
Keigo Kawase,
Igor Skobelev,
Sergei Gasilov,
Tetsuya Kawachi,
Hiroyuki Daido,
Toshiki Tajima,
Yoshiaki Kato,
Sergei Bulanov
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ABSTRACT: A tabletop ultra-bright, debris-free femtosecond-laser-driven cluster-based plasma soft X-ray source, which emits more than 10 12 photons/(srÁpulse) in the spectral range 1–10 nm within a 4 sr solid angle was developed. Using such source in combination with a high dynamic range LiF crystal soft X-ray detector allows obtaining contact and propagation-based phase-contrast images of nanostructures with 700 nm spatial resolutions in a wide field of view. It was demonstrated that the high precision of used techniques enable distinguishing inhomogeneity of measured intensities of ultrathin foils in the order of AE3%. All of this opens a new approach for PBPC imaging and metrology of full areas of free-standing or mesh-supported nano-thickness foils, or other nanostructures.
Japanese Journal of Applied Physics 06/2010; 49:06GK03. · 1.06 Impact Factor
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Alexander S. Pirozhkov,
Masaki Kando,
Timur Zh. Esirkepov,
Eugene N. Ragozin,
Anatoly Ya Faenov,
Tatiana A Pikuz,
Tetsuya Kawachi,
Akito Sagisaka,
Michiaki Mori,
Keigo Kawase, [......], Hideyuki Kotaki,
Hiromitsu Kiriyama,
Hajime Okada,
Nobuyuki Nishimori,
Kiminori Kondo,
Toyoaki Kimura,
Toshiki Tajima,
Hiroyuki Daido,
Yoshiaki Kato,
Sergei V. Bulanov
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ABSTRACT: X-ray devices are far superior to optical ones for providing nanometre spatial and attosecond temporal resolutions. Such resolution is indispensable in biology, medicine, physics, material sciences, and their applications. A bright ultrafast coherent X-ray source is highly desirable, for example, for the diffractive imaging of individual large molecules, viruses, or cells. Here we demonstrate experimentally a new compact X-ray source involving high-order harmonics produced by a relativistic-irradiance femtosecond laser in a gas target. In our first implementation using a 9 Terawatt laser, coherent soft X-rays are emitted with a comb-like spectrum reaching the 'water window' range. The generation mechanism is robust being based on phenomena inherent in relativistic laser plasmas: self-focusing, nonlinear wave generation accompanied by electron density singularities, and collective radiation by a compact electric charge. The formation of singularities (electron density spikes) is described by the elegant mathematical catastrophe theory, which explains sudden changes in various complex systems, from physics to social sciences. The new X-ray source has advantageous scalings, as the maximum harmonic order is proportional to the cube of the laser amplitude enhanced by relativistic self-focusing in plasma. This allows straightforward extension of the coherent X-ray generation to the keV and tens of keV spectral regions. The implemented X-ray source is remarkably easily accessible: the requirements for the laser can be met in a university-scale laboratory, the gas jet is a replenishable debris-free target, and the harmonics emanate directly from the gas jet without additional devices. Our results open the way to a compact coherent ultrashort brilliant X-ray source with single shot and high-repetition rate capabilities, suitable for numerous applications and diagnostics in many research fields.
04/2010;
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Tatiana A Pikuz,
Anatoly Ya Faenov,
Sergei V Gasilov,
Igor Yu Skobelev,
Yuji Fukuda,
Masaki Kando, Hideyuki Kotaki,
Takayuki Homma,
Keigo Kawase,
Yukio Hayashi,
Tetsuya Kawachi,
Hiroyuki Daido,
Yoshiaki Kato,
Sergei V Bulanov
[show abstract]
[hide abstract]
ABSTRACT: We demonstrate in-line phase-contrast imaging of nanothickness foils by using a relatively large, polychromatic, debris-free femtosecond-laser-driven cluster-based plasma soft x-ray source, and a high-resolution, large dynamic range LiF crystal detector. The spatial coherence length of radiation in our setup reached a value of 5 microm on the sample plane, which is enough to observe phase-contrast enhancement in the images registered by the detector placed only a few hundred micrometers behind the object. We have developed a tabletop soft x-ray emission source, which emits radiation within a 4pi sr solid angle, and which allows one to obtain contact and propagation-based phase-contrast imaging of nanostructures with 700 nm spatial resolutions. This advance could be of utility for metrology applications.
Applied Optics 11/2009; 48(32):6271-6. · 1.41 Impact Factor
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Hiromitsu Kiriyama,
Michiaki Mori,
Yoshiki Nakai,
Takuya Shimomura,
Manabu Tanoue,
Hajime Okada,
Shuji Kondo,
Shuhei Kanazawa,
Akito Sagisaka,
Izuru Daito, [......],
Hajime Sasao,
Daisuke Wakai,
Momoko Tanaka,
Yoshihiro Ochi,
Akira Sugiyama,
Hiroyuki Daido,
Sergei Bulanov,
Masato Koike,
Paul R. Bolton,
Shunichi Kawanishi
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ABSTRACT: We demonstrate the generation of greater than 1010 temporal contrast with over 1020 W/cm2 peak intensity pulses at a 10 Hz repetition rate from a Ti:sapphire chirped‐pulse amplification (CPA) laser system utilizing double CPA, optical parametric chirped‐pulse amplification (OPCPA), and cryogenic‐cooling techniques. We also successfully produce uncompressed output pulse energy exceeding 30 J, indicating potential for peak power at the 500 TW level.
AIP Conference Proceedings. 07/2009; 1153(1):3-6.
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Alexander S. Pirozhkov,
Masaki Kando,
Timur Zh. Esirkepov,
Yuji Fukuda,
Li‐Ming Chen,
Izuru Daito,
Koichi Ogura,
Takayuki Homma,
Yukio Hayashi, Hideyuki Kotaki, [......],
Takashi Kameshima,
Nobuyuki Nishimori,
Eugene N. Ragozin,
Anatoly Ya. Faenov,
Tatiana A. Pikuz,
Toyoaki Kimura,
Toshiki Tajima,
Hiroyuki Daido,
Yoshiaki Kato,
Sergei V. Bulanov
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ABSTRACT: A strongly nonlinear wake wave driven by an intense laser pulse can act as a partially reflecting relativistic mirror (the flying mirror) [S. V. Bulanov, et al., Bulletin of the Lebedev Physics Institute, No. 6, 9 (1991); S. V. Bulanov, et al., Phys. Rev. Lett. 91, 085001 (2003)]. Upon reflection from such mirror, a counter‐propagating optical‐frequency laser pulse is directly converted into high‐frequency radiation, with a frequency multiplication factor ∼ 4γ2 (the double Doppler effect). We present the results of recent experiment in which the photon number in the reflected radiation was at least several thousand times larger than in our proof‐of‐principle experiment [M. Kando, et al., Phys. Rev. Lett. 99, 135001 (2007); A. S. Pirozhkov, et al., Phys. Plasmas 14, 123106 (2007)]. The flying mirror holds promise of generating intense coherent ultrashort XUV and x‐ray pulses that inherit their temporal shape and polarization from the original optical‐frequency (laser) pulses. Furthermore, the reflected radiation bears important information about the reflecting wake wave itself, which can be used for its diagnostics.
AIP Conference Proceedings. 07/2009; 1153(1):274-284.
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ABSTRACT: For multiple laser pulse experiments, it is necessary to split a laser pulse. In order to split a short laser pulse without stretching the pulse width, the laser pulse should not pass through thick materials. For this reason, a pellicle beam splitter (BS) and/or a mirror with a hole are required as a BS for the short laser pulse. The focusing qualities of the laser pulse after passing through the pellicle BS and the mirror with a hole are the same as without the BS's. The laser pulse quality reflected by the BSs should be considered for the laser pulse. A pellicle BS is a thin foil, so, it is weak against vibrations. One should be careful about airflows and isolation from vibration sources. The spot size of the reflected laser pulse is consistent with the size reflected by a normal mirror. The energy loss is about 10% compared with a normal mirror. A mirror with a hole is strong against external vibrations. The reflected laser pulse has a doughnut shape. The reflected laser pulse is interfered due to the shape. In order to cleanly focus the laser pulse, the inside size of the doughnut should be smaller than a half size of the outside portion of the doughnut.
Review of Scientific Instruments 04/2007; 78(3):036102. · 1.37 Impact Factor
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Tomonao Hosokai,
Kenichi Kinoshita,
Takeru Ohkubo,
Akira Maekawa,
Mitsuru Uesaka,
Alexei Zhidkov,
Atsushi Yamazaki, Hideyuki Kotaki,
Masaki Kando,
Kazuhisa Nakajima,
Sergei V Bulanov,
Paolo Tomassini,
Antonio Giulietti,
Danilo Giulietti
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ABSTRACT: We use a one-shot measurement technique to study effects of laser prepulses on the electron laser wakefield acceleration driven by relativistically intense laser pulses (lambda=790 nm, 11 TW, 37 fs) in dense helium gas jets. A quasimonoenergetic electron bunch with an energy peak approximately 11.5 MeV[DeltaE/E approximately 10% (FWHM)] and with a narrow-cone angle (0.04pi mm mrad) of ejection is detected at a plasma density of 8 x 10(19) cm(-3). A strong correlation between the generation of monoenergetic electrons and optical guiding of the pulse in a thin channel produced by picosecond laser prepulses is observed. This generation mechanism is well corroborated by two-dimensional particle-in-cell simulations.
Physical Review E 04/2006; 73(3 Pt 2):036407. · 2.26 Impact Factor
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ABSTRACT: Formation of a plasma cavity with a shock wave in gas jets irradiated by tightly focused femtosecond laser pulses causes the wave break of the laser wake field at the front of the shock wave and, as a result, the injection of electrons into the acceleration phase of the wake-field wave. A strong crescentlike deformation of the cavity and a change in electron signal are observed with gas density growth. It is attributed to a mutual effect of the cavity on the laser pulse propagation and break of the plasma wake field due to refraction of the laser pulse.
Physics of Plasmas 09/2004; 11(10):L57-L60. · 2.15 Impact Factor
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ABSTRACT: Spatial and energy distributions of energetic electrons produced by an ultrashort, intense laser pulse with a short focal length optical system (Ti:sapphire, 12 TW, 50 fs, lambda=790 nm, f/3.5) in a He gas jet are measured. They are shown to depend strongly on the contrast ratio and shape of the laser prepulse. The wave breaking of the plasma waves at the front of the shock wave formed by a proper laser prepulse is found to make a narrow-cone (0.1pi mm mrad) electron injection. These electrons are further accelerated by the plasma wake field generated by the laser pulse up to tens of MeV forming a Maxwell-like energy distribution. In the case of nonmonotonic prepulse, hydrodynamic instability at the shock front leads to a broader, spotted spatial distribution. The numerical analysis based on a two-dimensional (2D) hydrodynamic (for the laser prepulse) and 2D particle-in-cell (PIC) simulation justifies the mechanism of electron acceleration. The PIC calculation predicts that electrons with energy from 10 to 40 MeV form a bunch with a pulse duration of about 40 fs.
Physical Review E 04/2003; 67(3 Pt 2):036407. · 2.26 Impact Factor
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ABSTRACT: We have generated relativistic electrons by interaction between a high intensity ultra‐short laser pulse (Ti:Sapphire, max 12TW, λ = 790nm , 50fs, 10Hz) and a supersonic gas‐jet. Shock‐wave free supersonic nozzles were designed, to perform well‐defined laser plasma interaction experiments. The energetic electrons (up to 40MeV) ejected from the gas‐jet with a narrow cone angle were observed under the conditions of the relativistic laser intensity of 1.0 × 1019 W/cm2 and the helium gas jet density range of 1.4 – 3.0 ×1019cm−3. It was found that generation of the narrow‐cone energetic electrons depended strongly on the laser pre‐pulse duration and that the proper pre‐pulse was essential for the generation. © 2002 American Institute of Physics
AIP Conference Proceedings. 12/2002; 647(1):628-633.
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ABSTRACT: The coherent wakefield excited by 2 TW, 50 fs laser pulses in a gas-jet plasma around 1018 cm−3 is measured with a time-resolved frequency domain interferometer. The density distribution of the helium gas is measured with a time-resolved Mach–Zehnder interferometer to search for the optimum laser focus position and timing in the gas jet. The results show an accelerating wakefield excitation of 20 GeV/m with good coherency, which is useful for ultrahigh gradient particle acceleration in a compact system. This is the first time-resolved measurement of laser wakefield excitation in a gas-jet plasma. © 2002 American Institute of Physics.
Physics of Plasmas 03/2002; 9(4):1392-1400. · 2.15 Impact Factor
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ABSTRACT: We have proposed the optical guiding of intense laser pulses by fast Z-pinch for channel-guided laser wakefield acceleration (LWFA). The method has been developed based on capillary discharge-pumped X-ray laser technique. A discharge through preionized helium gas driven by a current of 4.8 kA with a rise time of 15 ns proved able to produce a uniform guiding channel with good reproducibility, less than the time jitter of 1.8 ns. The observed guiding channel formation process was corroborated by 1D-MHD simulation. With this new guiding method, an intense Ti-sapphire laser pulse (λ = 790 nm, 2.2 TW, 90 fs, 1 × 1017 W/cm2) was transported through the channel over a distance of 2 cm, corresponding to 12.5 times the Rayleigh length. © 2001 Scripta Technica, Electr Eng Jpn, 136(3): 19–27, 2001
Electrical Engineering in Japan 07/2001; 136(3):19 - 27. · 0.09 Impact Factor
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Ryoichi Hajima,
Koji Yoshii,
Toru Ueda, Fumio Sakai, Hideyuki Kotaki,
Shuji Kondoh,
Masaki Kando,
Kenichi Kinoshita, Hideki Harano, Takahiro Watanabe,
Mitsuru Uesaka, Hideki Dewa
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ABSTRACT: A photo-cathode RF-gun and a chicane-based bunch-compressor are installed on an S-band linac which had been used for a UT-FEL experiment. Electron bunches extracted from the photo-cathode RF-gun are accelerated by an S-band structure up to 20 MeV and compressed by a chicane magnet. Since the bunch has very small longitudinal size and relatively low energy, coherent synchrotron radiation emitted from the bunch in the chicane creates a nonuniform energy loss in the bunch and degrades the performance of the bunch compressor. In the present paper, the performance of the bunch-compressor under the influence of coherent synchrotron radiation is studied. Preliminary experimental results are also presented.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment - NUCL INSTRUM METH PHYS RES A. 01/1999; 429(1):264-268.
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Mitsuru Uesaka,
Kenichi Kinoshita,
Takahiro Watanabe,
Toru Ueda,
Koji Yoshii,
Hideki Harano,
Kazuhisa Nakajima,
Atsushi Ogata,
Fumio Sakai, Hideyuki Kotaki,
Masaki Kando,
Hideki Dewa,
Shuji Kondo,
Yukio Shibata,
Kimihiro Ishi,
Mikio Ikezawa
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ABSTRACT: One of the S-band twin linacs (18L linac) of Nuclear Engineering Research Laboratory of University of Tokyo is modified in order to produce femtosecond electron single bunch for femtosecond X-ray generation via Thomson backward scattering, namely laser synchrotron radiation. Laser photocathode RF gun and chicane-type magnetic pulse compressor are installed at the S-band linac. 10 ps (FWHM) laser pulse generates 5 MeV, 10 ps (FWHM), 1 nC electron single bunch, which is accelerated up to 20 MeV in the S-band accelerating tube and compressed to 200 fs (FWHM) by the chicane. Design study has been performed by using the code of PARMELA and the installation has been finished. For precise and reliable measurement of the compressed pulse length, the comparison of measurement between the femtosecond streak camera and coherent transition radiation interferometry was carried out. Good agreement between them for 1–10 ps (FWHM) pulses was achieved. A new Michelson interferometer for the 200 fs pulse is now under construction.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 410(3):424-430. · 1.21 Impact Factor
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Ryoichi Hajima,
Koji Yoshii,
Toru Ueda,
Fumio Sakai, Hideyuki Kotaki,
Shuji Kondoh,
Masaki Kando,
Kenichi Kinoshita,
Hideki Harano,
Takahiro Watanabe,
Mitsuru Uesaka,
Hideki Dewa,
Kazuhisa Nakajima
[show abstract]
[hide abstract]
ABSTRACT: A photo-cathode RF-gun and a chicane-based bunch-compressor are installed on an S-band linac which had been used for a UT-FEL experiment. Electron bunches extracted from the photo-cathode RF-gun are accelerated by an S-band structure up to 20 MeV and compressed by a chicane magnet. Since the bunch has very small longitudinal size and relatively low energy, coherent synchrotron radiation emitted from the bunch in the chicane creates a nonuniform energy loss in the bunch and degrades the performance of the bunch compressor. In the present paper, the performance of the bunch-compressor under the influence of coherent synchrotron radiation is studied. Preliminary experimental results are also presented.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 429:264-268. · 1.21 Impact Factor
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ABSTRACT: We have studied optical guiding of high-intensity laser pulses using fast Z-pinch for channel guided laser wakefield acceleration (LWFA). A fast Z-pinch discharge can produce a long stable plasma channel which has a concave electron density profile in its core. We experimentally demonstrated the feasibility of optical guiding of high-intensity laser pulses using Z-pinch discharge channel. A ray-trace calculation of the Ti:Sapphire laser pulse in the channel has been done, which could well explain the experimental results.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 455(1):155-160. · 1.21 Impact Factor
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Hiromitsu Kiriyama,
Michiaki Mori,
Yoshiki Nakai,
Takuya Shimomura,
Manabu Tanoue,
Atushi Akutsu,
Hajime Okada,
Tomohiro Motomura,
Shuji Kondo,
Shuhei Kanazawa,
Akito Sagisaka,
Jinglong Ma,
Izuru Daito, Hideyuki Kotaki,
Hiroyuki Daido,
Sergei Bulanov,
Toyoaki Kimura,
Toshiki Tajima
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ABSTRACT: We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 1010 within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 1020 W/cm2.
Optics Communications.
