• Title/Summary/Keyword: Resonant Scattering

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Resonant Formation Rates of Muonic Molecular ion in Muon-Catalyzed Fusion (뮤온 촉매 핵융합에서 뮤온 분자 이온의 공명 형성율)

  • Im, Ki-Hak;Hong, Sang-Hee
    • Nuclear Engineering and Technology
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    • v.24 no.1
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    • pp.63-74
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    • 1992
  • The resonant formation rates of muonic molecular ion dtr in the muon-catalyzed fusion are calculated in various fuel temperatures and densities. The elastic scattering cross sections between t$\mu$ and deuterons are obtained by making use of the partial wave method. The transition property of the excited compound molecule [(dt$\mu$)dee]* derived by the impulse approximation in the form of a bound-state form factor. The radiative, Auger, and collisional deexcitations are considered as the deexcitation mechanisms of the excited dt$\mu$, and each deexcitation width is calculated as well as back decay width. The resultant reaction widths are used to calculate the formation cross sections of resonant dt$\mu$. The resonant formation rates for dt$\mu$-d and dt$\mu$-t collisions are computed as functions of fuel temperature and density. The calculations show that the resonant formation rates increase with fuel densities and have the maximum values at the particular temperatures where the relative collision energies are equal to the resonant ones.

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Wave scattering among a large number of floating cylinders

  • Kashiwagi, Masashi
    • Structural Engineering and Mechanics
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    • v.21 no.1
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    • pp.53-66
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    • 2005
  • When a large number of identical cylinders are placed in an array with equal separation distance, near-resonant phenomena may occur between cylinders at critical frequencies, and cause large wave forces on each element of the array. In this paper, 64 truncated circular cylinders arranged in 4 rows and 16 columns are considered to check occurrence of near-resonant phenomena and performance of theoretical predictions based on the potential flow. Experiments are conducted in head waves to measure the wave elevation along the longitudinal centerline of the model, and measured results are compared with numerical ones. Attention is focused on the spatial variation of the wave amplitude around the first near-trapped-mode frequency.

Analysis of Resonance Scattering Characteristics by Multi-layered Dielectric Gratings (다층 유전체 격자구조에 의한 공진 산란특성의 분석)

  • Ho, Kwang-Chun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.1
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    • pp.231-236
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    • 2017
  • The space harmonics generated by a plane-wave incident upon a multi-layered dielectric grating can undergo strong resonance scattering variations known as GMR(guided-mode resonance). To clarify these effects, we examine the field propagation and dispersion curve inside the grating region by using a rigorous equivalent transmission-line theory(RETT). The results show that, at the peak of a scattering resonance, the reflected mode is almost identical to a leaky wave that can be supported by the grating structure. Thus, we confirm and generalize previous research that has occurred GMR effect associated with the free-resonant character of leaky waves at multi-layered dielectric gratings. Quantitative simulation results illustrating the behavior of typical gratings are given, and the special case of normal incidence is discussed for TM mode.

POLARIZATION OF LYMAN α EMERGENT FROM A THICK SLAB OF NEUTRAL HYDROGEN

  • AHN, SANG-HTEON;LEE, HEE-WON
    • Journal of The Korean Astronomical Society
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    • v.48 no.3
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    • pp.195-202
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    • 2015
  • Star forming galaxies found in the early universe exhibit asymmetric Lyα emission line that results from multiple scattering in a neutral thick medium surrounding the Lyα emission source. It is expected that emergent Lyα will be significantly polarized through a large number of resonance scattering events followed by a number of successive wing scatterings. In this study we adopt a Monte Carlo method to calculate the polarization of Lyα transferred in a very thick static slab of HI. Resonantly scattered radiation associated with transitions between is only weakly polarized and therefore linear polarization of the emergent Lyα is mainly dependent on the number of off-resonant wing scattering events. The number of wing scattering events just before escape from the slab is determined by the product of the Doppler parameter a and the line center optical depth τ0, which, in turn, determines the behavior of the linear polarization of Lyα. This result is analogous to the study of polarized radiative transfer of Thomson scattered photons in an electron slab, where the emergent photons are polarized in the direction perpendicular to the slab when the scattering optical depth is small and polarized in the parallel direction when the slab is optically thick. Our simulated spectropolarimetry of Lyα shows that the line center is negligibly polarized, the near wing parts polarized in the direction parallel to the slab and the far wing parts are polarized in the direction perpendicular to the slab. We emphasize that the flip of polarization direction in the wing parts of Lyα naturally reflects the diffusive nature of the Lyα transfer process in thick neutral media.

Dynamics and Bleaching of Ground State in CdSe/ZnS Quantum Dots

  • Kim, J.H.;Kyhm, K.
    • Journal of the Optical Society of Korea
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    • v.10 no.4
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    • pp.184-187
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    • 2006
  • For resonant excitation of the ground state $1s^e-1S^h_{3/2}$, dynamics of 'the electron-hole pair in a CdSe quantum dot was investigated by degenerate pump-probe measurement. At low e-h pair densities, the decay of $1s^e-1S^h_{3/2}$ state is dominated by radiative recombination. As the number of the electron-hole pairs increases, new decay features become significant. Theoretical comparison suggests this is attributed to the bi-molecular and Auger-type scattering.

Radiation belt electron losses induced by wave-particle interactions

  • Summers, Danny
    • Bulletin of the Korean Space Science Society
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    • 2009.10a
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    • pp.32.2-32.2
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    • 2009
  • We examine cyclotron resonant interactions of radiation belt electrons with VLF chorus, plasmaspheric ELF hiss and electromagnetic ion cyclotron (EMIC) waves. Bounce-averaged diffusion rates depend on wave mode, equatorial pitch-angle, electron energy and L-shell. As well, diffusion rates can be sensitive to the latitudinal distributions of particle density and wave power. For different configurations of the plasmasphere, we calculate electron precipitation loss timescales due to combined scattering by VLF chorus, ELF hiss and EMIC waves.

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Analysis of Phase Noise of High Stable Microwave Phased Locked Oscillator with Gate Voltage Tunning (게이트 전압 제어에 의한 마이크로파 고안정 위상동기발진기의 위상잡음 특성 분석)

  • 김성용;이영철
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.5
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    • pp.863-871
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    • 2003
  • In this paper, we design a high stable Ku-band phase-locked dielectric resonant microwave oscillator with the gate voltage controls of p-HEMT. By adapting the nonlinear equivalent elements which affects phase noise of microwave oscillator, we optimize the nonlinear elements of p-HEMT to have low phase noise operation. Using the scattering parameters according to bias voltages, we designed the gate voltage control microwave dielectric resonant oscillator and phase-locked loop circuits is applied to have the high stable operations. Designed microwave oscillator as a local oscillator of digital microwave communication shows that output power is 9.17dBm at 10.75GHz and it's phase noise is -88dBc/Hz at 10KHz offset frequency.