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Effects of ion-ion collisions and inhomogeneity in two-dimensional kinetic ion simulations of stimulated Brillouin backscattering
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10.1063/1.2168405
/content/aip/journal/pop/13/2/10.1063/1.2168405
http://aip.metastore.ingenta.com/content/aip/journal/pop/13/2/10.1063/1.2168405
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

(Color online) Preservation of a Maxwellian: comparison of evolved ion velocity distribution functions with no collisions (bcoll3) and with CIC collisions (bcoll10) showing that the Maxwellian is preserved and there is similar self-heating.

Image of FIG. 2.
FIG. 2.

Snapshots of and ion velocity distribution functions from collisionless simulations with no incident laser (bcoll17) and with incident laser and strong SBBS (bcem33n). Also shown is the relative growth of kinetic energy in bcoll17 versus the time step.

Image of FIG. 3.
FIG. 3.

Collisionless 2D simulation bcoll18 with no incident laser and with digital smoothing of the ion charge density: snapshots of the and ion velocity distribution functions and relative ion kinetic energy growth versus time step.

Image of FIG. 4.
FIG. 4.

Collisionless 2D simulation bcoll20 with five-point-stencil digital smoothing of the ion charge density and strong SBBS: snapshots of the and ion velocity distribution functions over regions centered at , , and , and integrated in .

Image of FIG. 5.
FIG. 5.

(Color online) Relaxation of a strong temperature anisotropy: relative anisotropy versus time, and snapshots of the ion velocity distribution ( vs the square of velocities, and ).

Image of FIG. 6.
FIG. 6.

(Color online) Padé approximations for the Fokker-Planck drag and perpendicular velocity variance diffusion coefficients vs compared to those calculated numerically from error functions.

Image of FIG. 7.
FIG. 7.

Snapshots of the 3D ion velocity distribution function at and with and Fokker-Planck collisions preserving a Maxwellian (simulation bncoll3).

Image of FIG. 8.
FIG. 8.

Fokker-Planck collisional relaxation of a weak temperature anisotropy (initially and ) with and : relative temperature anisotropy versus dimensionless time using the same scales as in Fig. 5.

Image of FIG. 9.
FIG. 9.

Relaxation of an initially square velocity distribution function. Snapshots of ion velocity distribution functions from simulations with velocity-independent collisions (bcoll21) and Fokker-Planck collisions (bncoll6), and .

Image of FIG. 10.
FIG. 10.

Damping of an ion acoustic wave due to ion Landau damping and collisions for a collisionless simulation (bcoll30e) and a collisional simulation (bcoll30f, , ): mode amplitudes as functions of time at .

Image of FIG. 11.
FIG. 11.

(Color online) Peak and average SBBS reflectivities for parameters: , , , mass ratio, , and the Jones et al. collision model.

Image of FIG. 12.
FIG. 12.

SBS simulation bcoll26 with velocity-independent collisions and parameters: , , , real mass ratio for Be, , and instantaneous and average reflectivity, and ; reflected electromagnetic power spectrum versus time at and vs and time; power spectrum for vs and time. Here is the frequency of the SBBS ion acoustic wave.

Image of FIG. 13.
FIG. 13.

(Color online) SBS simulation bcoll26 with velocity-independent collisions and parameters: , , , real mass ratio for Be, , and , Electromagnetic potential vs and at ; and velocity distribution functions on the left side of the domain at and 1200.

Image of FIG. 14.
FIG. 14.

(Color online) Peak and average SBBS reflectivities as functions of collisionality (Fokker-Planck collisions) and corresponding linear gain exponent for parameters: , , , mass ratio, , , and .

Image of FIG. 15.
FIG. 15.

SBBS instantaneous and cumulative time-average reflectivities versus time, power spectrum for versus and time, and power spectrum for reflected electromagnetic power versus and time, for parameters: , , , mass ratio, , , , Fokker-Planck collisions, and (bcoll26nn).

Image of FIG. 16.
FIG. 16.

(Color online) Absolute value of the electromagnetic potential at , ion velocity distribution functions and at , and 900 in simulation bcoll26nn for parameters: , , , mass ratio, , , , and Fokker-Planck collisions with .

Image of FIG. 17.
FIG. 17.

Reflectivities as functions of time and power spectra for vs and time for parameters: , , , mass ratio, , , , the Fokker-Planck model (, bcoll28nn), and the Jones et al. model (, bcoll29s).

Image of FIG. 18.
FIG. 18.

Velocity distribution functions and on the left side of the domain at and 1050 for parameters: , , , mass ratio, , , , the Fokker-Planck model (, bcoll28nn), and the Jones et al. model (, bcoll29s).

Image of FIG. 19.
FIG. 19.

(Color online) Peak and average reflectivities vs linear convective gain exponents for backscatter intensity with parameters: , , and 0.2, mass ratio, , collisionless, . data shown in red (autoresonant) above data shown in blue (anti-autoresonant).

Image of FIG. 20.
FIG. 20.

SBBS instantaneous reflectivity and cumulative time-average reflectivity versus time, and power spectra plotted as functions of frequency and time for the reflected electromagnetic power at and , at and , and at and , for parameters: , , , mass ratio, , no collisions, and linear velocity gradient .

Image of FIG. 21.
FIG. 21.

Ion velocity distribution functions and at and 900 for simulation bgradv5d with linear velocity gradient showing the formation of a hot ion tail and transverse heating.

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2006-02-28
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Effects of ion-ion collisions and inhomogeneity in two-dimensional kinetic ion simulations of stimulated Brillouin backscattering
http://aip.metastore.ingenta.com/content/aip/journal/pop/13/2/10.1063/1.2168405
10.1063/1.2168405
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