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  • 2005-2009  (2)
  • 1995-1999  (66)
  • 1975-1979  (5)
  • 1
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The irradiation uniformity of the GEKKO XII laser [C. Yamanaka et al., IEEE J. Quantum Electron. QE-17 1639 (1981)] has been improved by using partially coherent light with angular spectral dispersion and by improving power balance among the beams. Implosion experiments with the uniformity-improved GEKKO XII have been carried out in order to demonstrate stable formation of the hot spark. The isentrope of the compressed pellet shell is controlled by adding a prepulse to enhance the ablative stabilization of the Rayleigh–Taylor instability. The implosion dynamics has been investigated by x-ray imaging and neutron diagnostics. The experimental results are compared with the mix model prediction based on the one-dimensional hydrodynamic simulation. The degradation of neutron yield is attributed to the low-mode asymmetry. Finally, recent results of planer target experiments on the ablative stabilization of the Rayleigh–Taylor instability are also presented. The observed linear growth rate was about 50% of the classical growth rate and was lower than that of the theoretical prediction, based on the Takabe formula combined with the one-dimensional simulation. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2063-2074 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Fusion pellet implosion by laser-generated x rays was investigated by means of time-integrated spectroscopic measurements. Deuterium fuel was seeded with a small amount of Ar in order to determine the electron temperature and the density of the compressed fuel from, respectively, the emission intensity ratio and the broadening of the Lyβ (Ar17+1s-3p) and Heβ (Ar16+1s2-1s3p) lines. Comparison of the observed results with volume-averaged temperatures and densities obtained from one-dimensional (1-D) fluid-dynamic simulations showed large discrepancies at maximum compression. One possible explanation is that the fuel is stably compressed until the beginning of pusher deceleration by collision with a reflected shock wave from the pellet center, and that further compression during the deceleration phase is terminated in particular for heavy stagnation cases. Similar results were obtained for fusion output. Experimentally obtained neutron yields were close to those from the 1-D simulations at the beginning of the deceleration but a factor of 10–100 less than those expected at maximum compression. These results were examined in terms of shell disintegration in the acceleration phase and pusher–fuel mixing at the contact surface in the deceleration phase due to growth of initial perturbations of the pellet resulting from fluid instabilities. © 1995 American Institute of Physics.
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 625-628 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We developed a two-dimensional spatial resolved high-speed UV sampling camera (HISAC) to study energy transport in laser-produced plasmas. The HISAC is composed of an optical bundle of fibers coupled to a streak camera to obtain a two-dimensional spatial resolution with a temporal resolution of less than a few 10 ps. This HISAC system was demonstrated in the experiments on inferred uniformity measurements of laser-ablation pressures as well as on energy transport in ultraintense laser-plasma interactions. Two-dimensional shock heating was temporally resolved in a hemispherical target, resulting in the distribution of the ablation pressure as a function of laser incidence angle. © 1999 American Institute of Physics.
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1177-1179 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Multicharged boron ions have been produced by a sputtering boride target in a 2.45-GHz electron cyclotron resonance (ECR) source. The target material is immersed in an ECR argon plasma along the geometrical axis of the mirror field, and dc bias voltages are applied. Extracted boron ion currents increase as the target approaches the ECR zone formed at the bottom of mirror trap although the argon charge state deteriorates. The increase of boron ion current is coincident with that of the solid angle subtended by the target at the ECR zone. Measurement of the boron flux shows that the increase of boron atoms sputtered into the ECR zone causes this enhanced production. Ratio of total boron to argon ion current and that of B2+ to B+ current are about 10% and 10%–20%, respectively. The B3+ current can be detected at low microwave power (∼150 W). The isotopes of boron are clearly separated in natural abundance ratio. © 1996 American Institute of Physics.
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 997-999 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A plasma source was developed for ion implanters capable of irradiating large-area substrates. Microwave discharge is performed by electron cyclotron resonance (ECR). A rectilinearly wide flux of magnetic induction is formed with two long permanent magnets with oppositely facing poles. The ECR zone formed inside a vacuum chamber is elongated in the direction along the pole faces. A waveguide slotted along its E plane is inserted between the magnets. The long slot radiates microwaves into the vacuum chamber through dielectric materials. These materials play the role of waveguide. Plasmas are uniformly generated in the direction along the slotted waveguide when it is terminated with a short plunger. This mechanism is analyzed by calculating radiation patterns of the slotted waveguide. © 1996 American Institute of Physics.
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1970-1977 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A toroidal electrostatic analyzer with a two-dimensional position-sensitive electron detector has been developed for the measurement of differential excitation cross sections in electron-ion collisions. The electron position is resolved simultaneously in the energy and angular dispersive directions of the analyzer. The present electron analyzer is specially designed with a narrow curved entrance slit and a wide exit slit coupled with an exit lens system after the toroidal deflector, which can give a wide energy dispersed range of 20% of the mean pass energy and a large angular range extending from 30° to 120°. The performance of the spectrometer has been studied by measuring the scattered electrons from Ar atoms and from a highly oriented pyrolytic graphite surface, indicating the usefulness of the present analyzer in electron spectroscopy. A brief description of the method for a spectrum transformation from Cartesian coordinates to polar coordinates is also presented. © 1999 American Institute of Physics.
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3873-3875 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An ion source of electron-cyclotron resonance using cusp magnetic field is designed. The field is generated with two cylindrical magnets polarized parallel to the axis of symmetry. Lines of magnetic induction are in this configuration longer than in conventional cusp machines. The plasma electrons escaping from a line cusp are repelled by applying negative potential to an electrode repeller. The repeller of low work function emits additional electrons. A whistler wave is launched through a helical antenna at a point cusp to produce overdense plasmas. An intense ion beam is formed by extracting ions at the other point cusp where the magnetic flux is focused. The repeller materials are sputtered at the line cusp and ionized in the plasma. The atomic flux from the cylindrical surface is focused at the center of plasma to give abundant ions from the solid materials. © 1995 American Institute of Physics.
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  • 8
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We developed an advanced Kirkpatrick–Baez (AKB) x-ray microscope which consisted of two hyperbolic mirrors and two elliptic mirrors. The spatial resolution of (approximately-less-than)3 μm was realized over ∼1 mm diam. This AKB microscope was used for x-ray imaging in laser fusion experiments. Laser absorption nonuniformity with a large wave number on a spherical solid target or a plane slab target was estimated by measurements of x-ray emission from the target surface with the microscope. The x-ray images of the imploded core plasmas were also obtained with the AKB microscope, changing the laser focus condition and the laser energy balance. © 1997 American Institute of Physics.
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  • 9
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Core plasmas of laser-imploded ICF targets were observed by using a 10-ps temporally resolved two-dimensional x-ray imaging technique. A multi-imaging x-ray pinhole camera was coupled to an x-ray streak camera, and two-dimensional images were reconstructed by handling the streaked image data. Image distortion of the system was evaluated and nonuniformity in sensitivity was corrected. The spatial resolution was 15 μm and the observed photon energy was 2.2–4.9 keV. Structures in the x-ray image of the core were found to be rapidly changing with 10-ps time scale. © 1995 American Institute of Physics.
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: The early stage of phase separation in aluminoborosilicate glass for liquid crystal display substrates was investigated using a scanning electron microscope (SEM) and small-angle X-ray scattering measurement device (SAXS). The phase-separated particles were detected with SAXS in samples in which no particle was observed with SEM. The particle diameter in an as-formed sample was 2 nm. The relationship between the diameter and heat-treatment time indicates that the phase separation proceeds by a diffusion-controlled process. Based on the results of Fourier-transform infrared spectroscopy, fast compositional change may occur in the early stage of phase separation.
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