The Review of Laser Engineering
Online ISSN : 1349-6603
Print ISSN : 0387-0200
ISSN-L : 0387-0200
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Volume 2, Issue 3
Displaying 1-20 of 20 articles from this issue
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  • SINGLE AND MULTI-BEAM LASER PELLET FUSION EXPERIMENTS
    M. Lubin, E. Goldman, J. Soures, L. Goldman, W. Friedman, S. Letzring, ...
    1974 Volume 2 Issue 3 Pages 141-162
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_141
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    Absorption, reflection, and symmetry measurements have been made on spherical laser fusion targets for both single beam (highly non-symmet-ric), and four beam (more symmetric) irradiation, at incident laser energies of up to 250 joules. Optical, charged particle and x-ray measurement techniques are used to show the essentially symmetric be-havior of the multi-beam irradiation. A measure of the effectiveness of lateral heat conductivity is obtained from a comparison of symmetric and non-symmetric irradiation results. Greatpr thp 30% of the incident laser energy at an intensity of 1015-1016W/cm2 results in elevated plasma temper4tures. The energy deposited in high energy photons is less than 10-3 of the absorbed energy. No distinct high energy Ion com-ponent is observed and, in any case, less than a few percent of the absorbed energy resides in ions of energies >10keV/nucleon.
    Time resolved optical diagnostics have uncovered the presence of an “after pulse” emitted from the plasma at the laser frequency but fol-lowing the trailing edge of the heating pulse.
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  • Comments on the Efficiency of the Laser
    Koichi Shimoda
    1974 Volume 2 Issue 3 Pages 163-167
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_163
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  • BASIC RESEARCH FOR NEW LASER GLASSESBASIC RESEARCH FOR NEW LASER GLASSES
    T. IZUMITANI
    1974 Volume 2 Issue 3 Pages 168-174
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_168
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    (1) Einstein's A-coefficent at 1.06μ becomes higher, as quantum efficiency increases and aprzrent lifetime decreases.
    (2) Inversion population (or stored energy) becomes larger as apparent lifetime increases.
    (3) It is interesting to note that cross section for stimulated emission (or A-coefficient) and stored energy (or inversion population) are in inversely proportional relationship.
    (4) From the view point of A-coefficient and inversion population, some phosphate glasses are considered to be the best host for Nd laser glasses.
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  • High Power CO2 Laser at Osaka
    S. Nakai, M. Matoba, S. Uda, H. Fujita, H. Toya, H. Nishimura, A. Naka ...
    1974 Volume 2 Issue 3 Pages 175-180
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_175
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  • Interaction of TEA CO2 Laser Light with Plasmas
    Masahiro YOKOYAMA, Chobei YAMABE, Eiji SETOYAMA, Aye THEIN, Kazuo SHUD ...
    1974 Volume 2 Issue 3 Pages 181-189
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_181
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    High power double discharge type TEA CO2 laser was used to study laser plasma interaction on laser produced carbon target plasma and plasma Focus device. The maximum output power was 0.3 GW and full width at half maximum intensity was 100ns.
    We measured the reflectivity of the laser light at 10.6μm in wavelength from the laser produced carbon plasma. The reflectivity showed a maximum (≈56%) at the laser power intensity of about 1.1 × 1010W/cm2, and at above this value, the reflectivity decreased. The absorption was introduced effectively above this intensity. The electron density and temperature were also measured.
    Heating of Plasma Focus by TEA CO2 Laser Light was also investigated near critical density region of Plasma Focus for 10.6μm TEA CO2 Laser Light. Preliminary experiment shows enhancement of X-ray emission with irradiation TEA CO2 Laser Light to focus plasma.
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  • CO2 Laser Interaction with Dense Plasma
    E. Fabre
    1974 Volume 2 Issue 3 Pages 190-196
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_190
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  • FAST ION PRODUCTION IN LASER-PRODUCED PLASMAS TO BE GIVEN AT THE JAPANESE LASER FUSION MEETING AT MT. FUJI NOVEMBER 7-9, 1974
    1974 Volume 2 Issue 3 Pages 198-202
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_198
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  • The Laser Interaction with Plasma
    C. Yamanaka, T. Sasaki, K. Yoshida, T. Tschudi, T. Yamanaka, J. Mizui, ...
    1974 Volume 2 Issue 3 Pages 203-212
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_203
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    Recently much attention has focused on the laser fusion scheme using high density plasma produced by the implosion. Institute of Laser Engineering, Osaka Universityscientific feasibility experiment on laser fùsion has come on a time schedule. But physics of the interaction betweenlaser and plasma, the technique of the high compression and the development of high power lasers are still important problems to be studied for the progress of laser fusion.
    As for the coupling of laser ileit and plasma, we have performed the laser bombarding experiments on the hydrogen and deuterium stick targets using a glass laser system “LEKKO-I” energy 50J in nanosecond pulse. The decrease of the re-flectivity has appeared at the laser intensity of one order larger than the threshold of the parametric instability. The phase modulation of the scattered light due to modulational instability was found.
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  • EXPERIMENTAL STUDY OF LASER DRIVEN COMPRESSION OF SPHERICAL GLASS SHELLS
    G. Charatis, J. Downward, R. Goforth, B. Guscott, T. Henderson, S. Hil ...
    1974 Volume 2 Issue 3 Pages 213-238
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_213
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    Laser-driven compression, core heating, and neutron generation are experimentally observed when DT-filled glass shells are illuminated by intense laser radiation. Requirements for obtaining strong compressions and neutron generation include nearly uniform illumination, energies on-target greater than 0.7 joules per nanogram of shell mass, symmetric target disassembly and on-target intensities 1015 W/cm2. The laser system, target illumination optics, targets, and laser target diagnostics are described in detail.
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  • Coupled Electron-Plasma and Ion-Acoustic Solitons Excited by Parametric Instability
    H. Ikezi, K. Nishikawa, H. Hojo, K. Mima
    1974 Volume 2 Issue 3 Pages 239-248
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_239
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    Self-modulation of the high-frequency electric field is observed when its frequency is near the electron plasma frequency. The localized field due to the self-modulation is found to make deprossions in the plasma density, and to be trapped in the deniiity dip which moves with the ion-acoustic speed. The depth of the dip reaches to 20% of the unperturbed density. The maximum amplitudes of the high-frequency field and the density dip are linearly proportional to each other. All these features are quantitatively explained by the results of the theory of coupled electron-plasma and ion-acoustic solitary waves.
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  • Two-Dimensional and Three-Di1nens ional Envelope Solitons
    Predhiman K. Kaw, Kyoji Nishikawa, Yugo Yoshida, Akira Hasegawa
    1974 Volume 2 Issue 3 Pages 249-259
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_249
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  • EFFECT OF RANDOM DENSITY FLUCTUATIONS ON PARAMETRIC INTERACTIONS IN A PLASMA
    P. Guzdar, P. Kaw, Y. Satya, A. Sen, A.K. Sundaram, R.K. Varma
    1974 Volume 2 Issue 3 Pages 260-274
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_260
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    We have analytically investigated the influence of quasi-static background random density fluctuations on three-wave parametric coupling processes in a plasma. As an example, the case of stimulated Raman scattering is discussed in detail. After Fourier analysing the time variable and eliminating the amplitude of one of the stimulated waves, the basic equation describing the parametric process reduces to a fourth order differential equation with coefficients which are randomfunctions of the position co-ordinate. Standard methods from theory of wave propagation in random media can now be used. Assuming |ε(x)|=|n(x)-n0/n0|<<1, analytical results correct to order |ε2| are derived for the limiting cases when the correlation length of turbulence is long or short compared to the wavelength of parametrically interacting waves. It is found that in a statistically homogeneous medium, the effect of fluctuations is to enhance the growth length i.e. to make the growth weaier. We next consider convective parametric amplification in a weakly inhomogeneous medium with random density fluctuations superimposed on it. The fourth order differential equation in position space is now Fourier transformed into a second order differential equation in k space. An expression for the convective amplification factor correct to order |ε2| is obtained for the case of long wavelength turbulence and shows that it is unaltered by the presence of background random density fluctuations.
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  • Laser Light Absorption with Density Profile Modifications
    W. Kruer, E. Valeo, K. Estabrook, B. Langdon, B. Lasinski
    1974 Volume 2 Issue 3 Pages 275-282
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_275
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  • Indications of Strongly Flux-Limited Electron Thermal Conduction in Laser Target Experiments
    K. Boyer, R.C. Malone, R.L. McCrory, R.L. Morse
    1974 Volume 2 Issue 3 Pages 283-291
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_283
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    Comparisons of calculations with experimental data indicate an anomalous reduction of electron thermal conduction when the incident laser irradiation is sufficiently intense. This reduction is interpreted as a flux limit, which is sufficiently restrictive to significantly affect heat flow at the intensities thought to be required for laser fusion. The direction of laser fusion efforts will be greatly influenced if electron thermal conduction is much less than predicted classically.
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  • Computer Study for Laser Fusion
    K.V. Roberts
    1974 Volume 2 Issue 3 Pages 292-296
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_292
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  • HYDRODYNAMIC APPROACH TO IMPLOSION OF TARGET PLASMA BY LASER HEATING
    Keishiro NIU, Takashi YABE
    1974 Volume 2 Issue 3 Pages 297-301
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_297
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  • Hydrodynamic Instabilities in Laser Fusion Targets
    G.B. Zimmerman
    1974 Volume 2 Issue 3 Pages 302-310
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_302
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  • IMPLOSION, STABILITY, AND BURN OF MULTISHELL FUSION PELLETS
    G.S. Fraley, W.P. Gula, D.B. Henderson, R.L. McCrory, R.C. Malone, R.J ...
    1974 Volume 2 Issue 3 Pages 311-320
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_311
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    Various multishell laser/e-beam fusion pellets are described. These include a design with hollow fuel inside a high Z pusher shell which gives greatly improved performance without extreme pulse shaping. The advantage of multishell, multimaterial pellets are discussed in general. Stability calcula-tions then show that Taylor instability on both the inside and outside of shells can amplify perturbations with spherical harmonic l-numbers of the order of 100 by factors exceeding ten thousand. However, by decreasing shell aspect ratios (r/Δr) and intensifying the ablation rate these amplifications can be greatly reduced. Acceptable instability growth seems attainable by using aspect ratios of the order of five or less and/or by operating in a less efficient exploding pusher mode. The effects of tamping by high Z material on thermonuclear burn are briefly discussed.
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  • Closing Remarks
    K. Boyer, M.J. Lubin, P.K. Kaw, C. Yamanaka
    1974 Volume 2 Issue 3 Pages 321-326
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_321
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  • [title in Japanese]
    Taijiro UCHIDA
    1974 Volume 2 Issue 3 Pages a1
    Published: September 30, 1974
    Released on J-STAGE: February 26, 2010
    DOIhttps://doi.org/10.2184/lsj.2.3_a1
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