Bragg scattering of EM waves from ion-beam mode wave packets

Many laser material processing applications require an optimized beam profile, e.g., ring shape or Top-Hat profiles with homogeneous intensity distribution. In this study, we show a beam shaping concept leading to a phase shifting element with binary height profile as well as a very low periodicity with near diffraction limited spot size. Further advantages of so-called Fundamental Beam Mode Shaping (FBS) elements are the simplified handling, and a high efficiency and homogeneity. The calculated height profile of FBS elements are transferred in fused silica substrates using a combination of microlithography technologies, reactive ion etching (RIE) and ion beam etching (IBE). The experiments demonstrated a linear relation between the etching depth after RIE and IBE. The optical evaluation of the manufactured FBS beam mode shaper confirmed the presented concept design.

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Properties of whistler mode wave packets at the leading edge of steepened magnetosonic waves: Comet Giacobini-Zinner

Planetary and Space Science ◽

10.1016/0032-0633(89)90004-4 ◽

1989 ◽

Vol 37 (2) ◽

pp. 167-182 ◽

Cited By ~ 22

Author(s):

Bruce T. Tsurutani ◽

Edward J. Smith ◽

Armando L. Brinca ◽

Richard M. Thorne ◽

Hiroshi Matsumoto

Keyword(s):

Wave Packets ◽

Leading Edge ◽

Whistler Mode ◽

Mode Wave ◽

Whistler Mode Wave

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Nonlinear Amplitude Oscillations of an Ion-Beam Mode

Physical Review Letters ◽

10.1103/physrevlett.32.1225 ◽

1974 ◽

Vol 32 (22) ◽

pp. 1225-1227 ◽

Cited By ~ 10

Author(s):

A. Lee ◽

S. Gleman ◽

W. D. Jones

Keyword(s):

Ion Beam ◽

Beam Mode

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Acoustic Behavior of Near Periodic Elastic Structures

Volume 3B: 15th Biennial Conference on Mechanical Vibration and Noise — Acoustics, Vibrations, and Rotating Machines ◽

10.1115/detc1995-0423 ◽

1995 ◽

Author(s):

Douglas M. Photiadis

Keyword(s):

Cross Section ◽

Wave Packets ◽

Acoustic Scattering ◽

Direct Interaction ◽

Bloch Wave ◽

Acoustic Properties ◽

Theoretical Development ◽

Naval Research ◽

Bragg Scattering ◽

Elastic Structures

Abstract Near periodic arrays of discontinuities have been predicted to have a significant impact on the acoustic properties of elastic structures. The discontinuities in the elastic properties of the structure produce a characteristic signature in the acoustic scattering cross section of the structure via two distinct mechanisms; a direct interaction producing acoustic Bragg scattering, and an indirect interaction wherein the discontinuities fundamentally alter the free waves of the structure. The locally propagating states of the pseudo-periodic system are Floquet or Bloch wave packets and the locations of the highlights in the cross section may be determined simply from the Bloch wavenumber via a phase matching argument. Predicting the resulting scattering levels requires an understanding of the propagation of the Bloch wave packets in the finite, pseudo-periodic structure. In the case of a thin ribbed cylindrical shell or plate this scattering mechanism can arise from flexural waves, and recent experimental results obtained at Naval Research Laboratory have demonstrated the importance of both this mechanism and Bragg scattering on the acoustic far field over a broad frequency range. In this paper, these results and the underlying theoretical development will be discussed.

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Solitary waves in an ion-beam-plasma system

Journal of Plasma Physics ◽

10.1017/s0022377800018146 ◽

1995 ◽

Vol 53 (2) ◽

pp. 235-243 ◽

Cited By ~ 7

Author(s):

Y. Nakamura ◽

K. Ohtani

Keyword(s):

Solitary Wave ◽

Solitary Waves ◽

Acoustic Waves ◽

Ion Beam ◽

Slow Mode ◽

Plasma System ◽

Ion Acoustic Wave ◽

Beam Plasma ◽

Ion Acoustic ◽

Beam Mode

Solitary waves in an ion-beam-plasma system are investigated theoretically using the pseudo-potential method, including finite temperatures of plasma ions and beam ions. The beam velocity is high enough to avoid ion-ion instability. Three kinds of solitary waves are possible, corresponding to ion- acoustic waves and to fast and slow space-charge waves in the beam. To observe the formation of solitary waves from an initial positive pulse, numerical simulations are performed. For the slow beam mode, a smaller solitary wave appears at the leading part of the pulse, which is a result of negative nonlinearity and anomalous dispersion of the slow mode, and is the opposite behaviour to the cases of the ion-acoustic wave and to the fast beam mode. Overtaking collisions of a solitary wave with a fast-mode solitary wave or with a slow-mode solitary wave are simulated.

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Observation of solitary waves in an ion-beam–plasma system

Journal of Plasma Physics ◽

10.1017/s0022377898006783 ◽

1998 ◽

Vol 60 (1) ◽

pp. 69-80 ◽

Cited By ~ 17

Author(s):

Y. NAKAMURA ◽

K. KOMATSUDA

Keyword(s):

Solitary Waves ◽

Ion Beam ◽

Density Ratio ◽

Maximum Amplitude ◽

Plasma System ◽

Measured Velocity ◽

Beam Plasma ◽

Plasma Device ◽

Double Plasma Device ◽

Beam Mode

Propagation of nonlinear space-charge waves in an ion-beam–plasma system is investigated in a double-plasma device. The velocity of the beam is high enough to avoid ion–ion instability. The density ratio of the beam to the plasma is kept high ([les ]0.6), which makes the maximum amplitude of solitary waves large. The measured velocity and width of the compressional solitary waves of the fast and the slow beam mode are compared with predictions of the pseudopotential method in which the temperatures of beam and plasma ions are taken into consideration. Reasonable agreement is obtained between the experimental and theoretical results.

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