論文 - 中井　光男

High-order harmonics of 248.6-nm KrF laser from helium and neon ions

SG Preston, A Sanpera, M Zepf, WJ Blyth, CG Smith, JS Wark, MH Key, K Burnett, M Nakai, D Neely, AA Offenberger

PHYSICAL REVIEW A   53 ( 1 )   R31 - R34   1996年1月

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We report high harmonic generation from a 248.6-nm KrF laser giving harmonic orders up to the 37th (67 Angstrom) in a helium gas jet and the 35th (71 Angstrom) in neon, for laser intensities up to 4 x 10(17) W/cm(2) in 380-fs pulses. These observations are interpreted using theoretical modeling that identifies the ion species He+, Ne+, and Ne2+ as the sources of the highest harmonics.

Development and application of ultra-bright laser and harmonic XUV sources 査読

MH Key, TW Barbee, JW Blyth, K Burnett, GF Cairns, AE Dangor, T Ditmire, A Djaoui, LB DaSilva, A Demir, A Dyson, AP Fews, EE Fill, P Gibbon, P Lee, S Healy, M Holden, DH Kalantar, NS Kim, CLS Lewis, Y Li, J Lin, P Loukakos, AG McPhee, Mercer, I, S Moustaizis, M Nakai, D Neely, P Norreys, AA Offenberger, GJ Pert, SG Preston, BA Remmington, A Sanpera, D Schlogl, CG Smith, R Smith, J Steingruber, GJ Tallents, F Walsh, JS Wark, J Warwick, E Wolfrum, M Zepf, J Zhang

X-RAY LASERS 1996   ( 151 )   9 - 16   1996年

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Experimental work with high intensity lasers at the Rutherford Appleton Laboratory has led to the production of both XUV laser and XUV harmonic sources with extreme brightness. In particular an efficient XUV laser source has been developed based on collisionally excited neon -like Ge XXIII(J=0-1) at 19.6 nm using the high power glass laser Vulcan generating 75 ps pulses. With Vulcan operating in sub -ps CPA mode, extremely powerful and short wavelength XUV high harmonic sources have been obtained by irradiation of solid targets and recombinant laser action with high gain has been demonstrated with fibre targets. An ultra-bright Krypton-fluoride laser system, Sprite(recently upgraded to a new configuration Titania) has produced the shortest harmonic wavelength (6.7 nm) and has been used to assess the possibilities of optical field ionised recombinant laser action with gas jet targets. The Ge XUV laser has been successfully applied in fusion research for radiographic measurements of the effect of laser speckle on the hydrodynamic stability of laser accelerated thin foils. The present status of the work, the comparative performance of the XUV laser and harmonic sources and near-term future directions are reviewed.

Implosion experiments with uniformity-improved GEKKO XII: Overview

Y Kato, H Azechi, H Takabe, N Miyanaga, T Kanabe, T Norimatu, H Nishimura, H Shiraga, M Nakai, R Kodama, KA Tanaka, M Takagi, M Nakatsuka, K Nishihara, K Mima, T Yamanaka, S Nakai

LASER INTERACTION AND RELATED PLASMA PHENOMENA   pp101-107 ( 369 )   101 - 107   1996年

rho Delta R measurement of imploded cryogenic foam target by DD-protons

Y Kitagawa, KA Tanaka, M Nakai, T Yamanaka, K Nishihara, H Azechi, N Miyanaga, T Norimatsu, T Kanabe, C Chen, A Richard, M Sato, H Furukawa, S Nakai

LASER INTERACTION AND RELATED PLASMA PHENOMENA   pp.136-142 ( 369 )   136 - 141   1996年

Stimulated Raman scattering from two overlapped 527 nm laser beams 査読

M Tsukamoto, KA Tanaka, K Mima, R Kodama, M Kado, S Nakaji, A Nishiguchi, M Nakai, T Norimatsu, K Nishihara, T Yamanaka, S Nakai

LASER INTERACTION AND RELATED PLASMA PHENOMENA   ( 369 )   459 - 464   1996年

DYNAMIC BEHAVIOR OF RIPPLED SHOCK-WAVES AND SUBSEQUENTLY INDUCED AREAL-DENSITY-PERTURBATION GROWTH IN LASER-IRRADIATED FOILS (VOL 74, PG 3608, 1995) 査読

T ENDO, K SHIGEMORI, H AZECHI, A NISHIGUCHI, K MIMA, M SATO, M NAKAI, S NAKAJI, N MIYANAGA, S MATSUOKA, A ANDO, KA TANAKA, S NAKAI

PHYSICAL REVIEW LETTERS   75 ( 15 )   2908 - 2908   1995年10月

Observation of Plasma Density Profile in Cylinder-Type X-Ray-Driven Fusion Target by GIR Method

Yasushi Oshikane, Masahiro Tsukamoto, Kazuo A. Tanaka, Shin-ichi Nakaji, Tomoki Ohnishi, Hiroyuki Hashimoto, Mitsuo Nakai, Hideaki Takabe, Kunioki Mima, Yoshiaki Kato, Sadao Nakai, Akio Nishiguchi, Osaka Institute of Technology

Bulletin of The American Physical Society, Vol.40, No.11, p.1783   1995年10月

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【工学部論文データから移行】

AREAL DENSITY-MEASUREMENT OF IMPLODED CRYOGENIC TARGET BY ENERGY PEAK SHIFT OF DD-PRODUCED PROTONS

Y KITAGAWA, KA TANAKA, M NAKAI, T YAMANAKA, K NISHIHARA, H AZECHI, N MIYANAGA, T NORIMATSU, T KANABE, C CHEN, A RICHARD, M SATO, H FURUKAWA, S NAKAI

PHYSICAL REVIEW LETTERS   75 ( 17 )   3130 - 3133   1995年10月

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DD-produced protons are used to measure the imploded fuel-shell areal density rho Delta R. Twelve green beams of the GEKKO XII laser directly imploded a cryogenic foam-shell target containing a liquid or solid D-2 fuel. The proton emission is detected through a dipole magnet on a CR-39 plate, whose energy shift from 3.02 MeV yielded the maximum rho Delta R of 10 mg/cm(2) or the density of 6 g/cm(3), in agreement with that from the secondary neutron method within a factor of 2. The proton energy spread is sensitive to the laser energy imbalance.

CRYOGENIC DEUTERIUM TARGET EXPERIMENTS WITH THE GEKKO-XII, GREEN LASER SYSTEM

KA TANAKA, T YAMANAKA, K NISHIHARA, T NORIMATSU, N MIYANAGA, H SHIRAGA, M NAKAI, Y KITAGAWA, R KODAMA, T KANABE, H AZECHI, M HEYA, T JITSUNO, M KADO, K MIMA, M NAKATSUKA, A NISHIGUCHI, H TAKABE, M TAKAGI, K TSUBAKIMOTO, M TSUKAMOTO, Y KATO, Y IZAWA, S NAKAI

PHYSICS OF PLASMAS   2 ( 6 )   2495 - 2503   1995年6月

DYNAMIC BEHAVIOR OF RIPPLED SHOCK-WAVES AND SUBSEQUENTLY INDUCED AREAL-DENSITY-PERTURBATION GROWTH IN LASER-IRRADIATED FOILS

T ENDO, K SHIGEMORI, H AZECHI, A NISHIGUCHI, K MIMA, M SATO, M NAKAI, S NAKAJI, N MIYANAGA, S MATSUOKA, A ANDO, KA TANAKA, S NAKAI

PHYSICAL REVIEW LETTERS   74 ( 18 )   3608 - 3611   1995年5月

STIMULATED RAMAN-SCATTERING FROM SYMMETRICALLY ILLUMINATED 2-LAYERED SPHERICAL TARGETS WITH 527-NM LASER LIGHT 査読

M TSUKAMOTO, KA TANAKA, K MIMA, M KADO, S MIYAMOTO, M NAKAI, T NORIMATSU, M TAKAGI, K NISHIHARA, T YAMANAKA, S NAKAI, A NISHIGUCHI

PHYSICS OF PLASMAS   2 ( 2 )   486 - 492   1995年2月

Erratum: Dynamic behavior of rippled shock waves and subsequently induced areal-density-perturbation growth in laser-irradiated foils (Physical Review Letters (1995) 75, 15) 査読

Endo T, Shigemori K, Azechi H, Nishiguchi A, Mima K, Sato M, Nakai M, Nakaji S, Miyanaga N, Matsuoka S, Ando A, Tanaka K.A, Nakai S

Physical Review Letters   75 ( 15 )   1995年

HIGH HARMONIC-GENERATION WITH A CPA KRF LASER 査読

M ZEPF, W BLYTH, MH KEY, M NAKAI, SG PRESTON, JS WARK

LASER INTERACTION WITH MATTER   ( 140 )   467 - 470   1995年

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High harmonics have been observed from a 0.8 TW, 350-fs KrF CPA laser focused to 8 x 10(17) W cm(-2) in gas jet targets. Estimates of the absolute conversion efficiencies have been made. The efficiency and relative strength of the harmonics was found to be largely independent of the position of the laser focus within the gas jet, and of the density, suggesting a coherence length limited by dephasing effects due to plasma electrons. The highest harmonics are attributed to ions rather than neutrals.

IMPLOSION EXPERIMENTS OF CRYOGENICALLY COOLED TARGETS 査読

T YAMANAKA, KA TANAKA, K NISHIHARA, T NORIMATSU, H SHIRAGA, Y KITAGAWA, N MIYANAGA, H AZECHI, H NISHIMURA, M NAKAI, R KODAMA, M HEYA, M TAKAGI, Y IZAWA, T KANABE, T JITSUNO, M NAKATSUKA, K MIMA, M MURAKAMI, S NAKAI, T ENDO, C YAMANAKA

LASER INTERACTION WITH MATTER   ( 140 )   25 - 28   1995年

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Cryogenically cooled deuterium targets with plastic ablator are imploded as well as plastic targets with deuterium gas at laser intensities of 4-5x10(14) W/cm(2) and 1-2x10(14) W/cm(2). The low intensity shots showed neutron yields normalized by 1-D simulation to be one tenth up to convergence ratio of 30, while those at the high intensity are one hundredth. The observed neutron yields and density radius product rho Rs are respectively 10(8) and 8 mg/cm(2) for cryogenic liquid targets. 2-D x-ray images obtained with a 10 ps temporal resolution camera reveal previously undiscovered information of imploding core plasmas.

Observation of Raman light in expanding plasmas from two-layered spherical targets irradiated with 527 nm laser

M. Tsukamoto, K. A. Tanaka, K. Mima, M. Kado, S. Miyamoto, M. Nakai, T. Norimatsu, M. Takagi, K. Nishihara, T. Yamanaka, S. Nakai

Technol. Repts. Osaka Univ.   1994年10月

RECENT PROGRESS IN LASER FUSION-RESEARCH AT OSAKA-UNIVERSITY - UNIFORMITY AND STABILITY ISSUES

K NISHIHARA, M MURAKAMI, H AZECHI, T JITSUNO, T KANABE, M KATAYAMA, N MIYANAGA, M NAKAI, M NAKATSUKA, K TSUBAKIMOTO, S NAKAI

PHYSICS OF PLASMAS   1 ( 5 )   1653 - 1661   1994年5月

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Improvement of laser irradiation uniformity in the Gekko XII system [IEEE J. Quantum Electron. QE-17, 1639 (1981)], both single beam pattern and power balance, is discussed. Substantial reduction of laser absorption nonuniformity is obtained for spherical harmonic modes greater than 15 by introducing spectrally dispersed amplified spontaneous emission. No perturbation growth is observed in flat foils accelerated by spectrally dispersed amplified spontaneous emission. Dependences of laser absorption uniformity on beam pattern and power imbalance are investigated in detail. The design goal of the power imbalance in the precision Gekko XII system is 3% in peak to valley, and laser absorption nonuniformity is estimated to be a few percent. Growth of hydrodynamic instabilities is analyzed for high convergence ratio implosions in the precision Gekko XII system.

IMPLOSION OF D-2 TEMPERATURE-CONTROLLED CRYOGENIC FOAM TARGETS WITH PLASTIC ABLATORS

A RICHARD, KA TANAKA, K NISHIHARA, M NAKAI, M KATAYAMA, YO FUKUDA, T KANABE, Y KITAGAWA, T NORIMATSU, M NAKATSUKA, T YAMANAKA, M KADO, T KAWASHIMA, C CHEN, M TSUKAMOTO, S NAKAI

PHYSICAL REVIEW E   49 ( 2 )   1520 - 1526   1994年2月

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The implosion hydrodynamics of temperature-controlled cryogenic deuterium foam targets with plastic ablators is investigated. The experimental data recorded with x-ray imaging systems are compared to a one-dimensional (1D) simulation. The ablation front trajectories derived from x-ray streak-camera data agree with 1D simulation. However, an x-ray core emission is observed at an earlier time, and for a longer duration than that predicted. For the three liquid-fuel shots, the convergence ratios are, respectively, 0.4, 0.9, and 0.7 times that predicted by the ID simulation.

4.8-KEV X-RAY BACKLIGHT FRAMING METHOD FOR OBSERVING IMAGES OF SOFT-X-RAY-DRIVEN FUSION CAPSULES

M KATAYAMA, H SHIRAGA, M NAKAI, T KOBAYASHI, Y KATO

REVIEW OF SCIENTIFIC INSTRUMENTS   64 ( 3 )   706 - 710   1993年3月

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We report on a diagnostic method for observing the implosion asymmetry of soft-x-ray-driven fusion capsules. The method consists of an x-ray backlight source using a 4.8-keV quasi-monochromatic titanium x-ray source and a fast multiframe x-ray imaging system. With the proper combination of spectral filters and photocathode to reduce intense background x rays from a gold cavity plasma, x-ray backlighting images of the fusion capsules have been successively obtained with spatial and temporal resolutions of 20 mum and 80 ps, respectively. These images are used to study the implosion velocity and the lower-mode distortion caused by x-ray irradiation nonuniformity on the imploding fusion capsule.

IMPLOSION EXPERIMENTS INVOLVING CRYOGENIC FOAM TARGETS WITH PLASTIC ABLATOR

T YAMANAKA, K NISHIHARA, KA TANAKA, T NORIMATSU, Y KITAGAWA, M NAKAI, M TAKAGI, A RICHARD, M KATAYAMA, C CHEN, M KADO, M TSUKAMOTO, T JITSUNO, R KODAMA, H AZECHI, N MIYANAGA, K MIMA, M NAKATSUKA, S NAKAI, T KANABE, M MURAKAMI, A NISHIGUCHI, C YAMANAKA

PLASMA PHYSICS AND CONTROLLED NUCLEAR FUSION RESEARCH 1992, VOL 3   pp 151-158   151 - 158   1993年

PHYSICS HIGHLIGHTS OF THE GEKKO12-PROGRAM 査読

K MIMA, S NAKAI, H AZECHI, A NISHIGUCHI, H TAKABE, N MIYANAGA, H NAKANO, M NAKAI, M KATAYAMA, K NISHIHARA, N NAKATSUKA, T JITSUNO, K TANAKA, H NISHIMURA, H SHIRAGA, T ENDO, T YAMANAKA, Y KATO, C YAMANAKA

PLASMA PHYSICS AND CONTROLLED FUSION   34 ( 13 )   1775 - 1783   1992年12月

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Recently, hollow shell pellets have been imploded uniformly by the Gekko 1 2 laser system to be compressed to several hundreds g/cm3. The compressed density has been measured both by the neutron activation methods and the electron degeneracy measurement. The densities given by the above two methods are consistent.
The target parameter dependences of the density are analyzed with die one climensional implosion simulation code. Except the case of high convergence ratio implosion, the compressed plasma density obtained by the simulation code with nonlocal heat transport and/or high energy electron preheating agrees with the experimental results. As for the high convergence implosion, the one dimensional simulation does not give good prediction of the implosion, in particular for the neutron yield. Actually, the experimental neutron yield for the convergence ratio higher than 20 is lower by more than two orders of magnitude than the simulation value.
The preheating and stability are the key physics for die high density compression. As for the preheating, it turns out that the two plasmon decay plays an important role in the accelerated shell preheating. As for the stability, the initial target surface roughness and the laser irradiation non-uniformity are carefully checked. By the theoretical stability analysis, the stability of the high density compression is found to be marginal. Therefore, we are afraid that the neutron yield may degradate by the hot-cold plasma mixing. The details of the Rayleigh-Taylor instability analysis and experiments are discussed in the text.