Abstract

A Thomson scattering opticals system is described with the following characteristics: (1) it allows scattering angles down to 1 mrad before collection optics interfere with beam dumping; (2) it gives excellent k resolution for angles of ≳1.5 mrad; (3) it collects light from a scattering volume which can be variably positioned without optical realignment; and (4) it is compact in size. The design, test data, and an application to ruby-laser scattering from 100-μm wavelength plasma waves are presented.

© 1985 Optical Society of America

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References

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  1. J. Sheffield, Plasma Scattering of Electromagnetic Radiation (Academic, New York, 1975).
  2. C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
    [CrossRef]
  3. For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
    [CrossRef] [PubMed]
  4. The plasma wave spectrum is actually a surface in kykz space, i.e., S(ky,kz). The frequency shift due to the finite frequency (ωp) of the plasma wave gives a k shift to the scattered light of δk = ωp/c, which is mainly in the y direction, perpendicular to the propagation direction (z direction) of the wave. Thus the spectrum one measures is actually S(ωp/c,kz), which we call the kz spectrum at ky = ωp/c or simply the kz spectrum. For a stationary scatterer, such as a grating, ωp is zero.
  5. The degree of collimation of the scattered beam and, therefore, its spot size depend on the length or number of periods of the coherent scatterer. See Fig. 3(c) and related text.
  6. R. E. Slusher, C. M. Surko, “Study of Density Fluctuations in Plasmas by Small Angle CO2 Laser Scattering,” Phys. Fluids 23, 472 (1980).
    [CrossRef]

1985 (1)

For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
[CrossRef] [PubMed]

1984 (1)

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

1980 (1)

R. E. Slusher, C. M. Surko, “Study of Density Fluctuations in Plasmas by Small Angle CO2 Laser Scattering,” Phys. Fluids 23, 472 (1980).
[CrossRef]

Clayton, C. E.

For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
[CrossRef] [PubMed]

Darrow, C.

For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
[CrossRef] [PubMed]

Dawson, J. M.

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Forslund, D. W.

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Joshi, C.

For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
[CrossRef] [PubMed]

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Katsouleas, T.

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Kindel, J. M.

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Mori, W. B.

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Sheffield, J.

J. Sheffield, Plasma Scattering of Electromagnetic Radiation (Academic, New York, 1975).

Slusher, R. E.

R. E. Slusher, C. M. Surko, “Study of Density Fluctuations in Plasmas by Small Angle CO2 Laser Scattering,” Phys. Fluids 23, 472 (1980).
[CrossRef]

Surko, C. M.

R. E. Slusher, C. M. Surko, “Study of Density Fluctuations in Plasmas by Small Angle CO2 Laser Scattering,” Phys. Fluids 23, 472 (1980).
[CrossRef]

Umstadter, D.

For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
[CrossRef] [PubMed]

Nature London (1)

C. Joshi, W. B. Mori, T. Katsouleas, J. M. Dawson, J. M. Kindel, D. W. Forslund, “Ultrahigh Gradient Particle Acceleration by Intense Laser-Driven Plasma Density Waves,” Nature London 311, 525 (1984).
[CrossRef]

Phys. Fluids (1)

R. E. Slusher, C. M. Surko, “Study of Density Fluctuations in Plasmas by Small Angle CO2 Laser Scattering,” Phys. Fluids 23, 472 (1980).
[CrossRef]

Phys. Rev. Lett. (1)

For more details on this experiment, see C. E. Clayton, C. Joshi, C. Darrow, D. Umstadter, “Relativistic Plasma Wave Excitation by Collinear Optical Mixing,” Phys. Rev. Lett. 54, 2343 (1985).
[CrossRef] [PubMed]

Other (3)

The plasma wave spectrum is actually a surface in kykz space, i.e., S(ky,kz). The frequency shift due to the finite frequency (ωp) of the plasma wave gives a k shift to the scattered light of δk = ωp/c, which is mainly in the y direction, perpendicular to the propagation direction (z direction) of the wave. Thus the spectrum one measures is actually S(ωp/c,kz), which we call the kz spectrum at ky = ωp/c or simply the kz spectrum. For a stationary scatterer, such as a grating, ωp is zero.

The degree of collimation of the scattered beam and, therefore, its spot size depend on the length or number of periods of the coherent scatterer. See Fig. 3(c) and related text.

J. Sheffield, Plasma Scattering of Electromagnetic Radiation (Academic, New York, 1975).

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Figures (4)

Fig. 1
Fig. 1

Schematic of the experimental setup used to measure the properties of a 100-μm wavelength electron plasma wave excited by a CO2 laser beam using small-angle collective Thomson scattering.

Fig. 2
Fig. 2

Cross sections of the Thomson scattering optics in the vertical (top) and horizontal (bottom) planes. The dashed lines indicate the path of the scattered light. The numbers below each lens indicate the distance in centimeters to the scattering volume. S1,S2 = spherical lenses; C1,C2,C3 = cylindrical lenses; H = horizontal line focus; V = vertical line focus; δ = horizontal deflection of scattered light from probe beam. Focal lengths in millimeters are: S1 = 127, S2 = 76, C1 = 300, C2 = 150, C3 = 1100.

Fig. 3
Fig. 3

Calibration of scattering apparatus for k measurements using a He–Ne laser. Transmission gratings (reticles) of various spatial frequencies were used as the scatterer. (a) Diffracted orders at the detection plane. The numbers indicate the grating line spacing. (b) Plots of the order separation δ vs grating frequency taken from (a). (c) Radial intensity profiles of a first-order spot from a 100-μm grating for various numbers N of grating periods illuminated. The horizontal scale is normalized and shifted so as to be equivalent to the kk scale of Fig. 4(b).

Fig. 4
Fig. 4

Data from collective scattering from the electron plasma wave excited by collinear optical mixing: (a) frequency spectra of the scattered light; (b) angular spectrum of the scattered light corresponding to the kz spectrum of the plasma waves. Error bars indicate standard deviation of several shots. The horizontal bar is the fiber optic size. Δω and Δk are the theoretically expected frequency and z component wave number of the plasma wave.

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