Nonlinear inverse bremsstrahlung and highly anisotropic electron distributions

Porshnev, P. I.; Khanevich, E. I.; Bivona, S.; Ferrante, G.

doi:10.1103/physreve.53.1100

Cited by 17 publications

(12 citation statements)

References 13 publications

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“…For V E greater than V T (t) by a factor larger than 4 the same initial EDF first becomes elongated in the perpendicular direction to that of the laser polarization, and afterwards evolves as in the case V E /V T (t) > 2÷4. In both cases, far from the critical transition values of V E /V T (t), the field modified EDF may profitably be approximated by an EDF with a maxwellian shape and two different temperatures, perpendicular and parallel to the laser electric field (anisotropic bi-maxwellian EDF) [15][16][17][18]. 4).…”

Section: Account Of the Plasma Influencementioning

confidence: 99%

Influence of a plasma medium on laser assisted radiative recombination

et al. 2004

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The problem of laser assisted radiation recombination, taking into account the influence of the plasma in which the elementary process takes place, is investigated theoretically. Among the reported results, remarkable broadening and enhancement of the X-ray photon emission spectrum is found, provided some conditions are met. First, a sufficiently intense laser field must assist the process. For enhancement, the intensity must be such that the amplitude of the quiver electron velocity be comparable or slightly larger than the electron thermal velocity. For broadening it is important that at the level of the elementary act of recombination several multiphoton channels be open. A judicious compromise between the plasma temperature and the field intensity is necessary to have many effective slow electrons able to absorb large numbers of photons from the assisting laser field to be converted into X-ray photons. Emitted power spectra per steradian and frequency unit of the emitted photon J(ω x ) in a.u. as a function ω x for a Maxwellian EDF, ion charge Z=3, ω L =0.057 a.u., laser intensity I L = 6×10 15 W/cm 2 , different values of plasma temperature: dotted line T =1a.u. and R=7.3; thick line T=1,5 a.u. and R=5.9; thin line T= 2 a.u. and R=5.1

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Section: Account Of the Plasma Influencementioning

confidence: 99%

Influence of a plasma medium on laser assisted radiative recombination

et al. 2004

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“…With the expressions for the collision integrals (5) and (7), equation (4) is a nonlinear integro-differential equation for the EDF in the presence of a laser field. A huge number of papers (see, for instance, [3,4,[6][7][8][9][10][11][12][13][14][15][27][28][29][30][31][32]) have been devoted to the solution of this equation. Nevertheless, a general solution to this equation has still not been found.…”

Section: Basic Kinetic Equationmentioning

confidence: 99%

“…In particular, it has been shown that when the inequalities Zv T > v E > v T are fulfilled an anisotropic EDF is formed, which is well approximated by a bi-Maxwellian. Another way to deal with the problem under examination is to solve numerically the appropriate kinetic equation, yielding a two-dimensional EDF [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Response of Piezoelectric Lead–Zirconate–Titanate to Hypervelocity Silver Particles

Miyachi

Hasebe

Itô

et al. 2003

Jpn. J. Appl. Phys.

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A short review of the properties of electron distribution functions in a fully ionized plasma in the presence of high-frequency laser radiation is given. Weak and strong field situations are considered. In a weak field, when the amplitude of the electron quiver velocity in the field is smaller than the electron thermal velocity, the distributions of both the thermal and the under thermal electrons are considered. The conditions are shown when it is necessary to take into account the deviation of the electron distribution function from a Maxwellian. In a strong field the kinetics of the electron is strongly determined by the field intensity and the distribution function in the coordinate system oscillating with the radiation frequency is anisotropic under broad physical conditions, and may be approximated by a bi-Maxwellian distribution with two different transverse and longitudinal temperatures. Among the most peculiar features of the laser modified electron distribution functions, it is worth quoting the pathway of the anisotropy evolution. Depending on the laser field parameters, the distribution function in the initial stages of the laser-plasma interaction is either elongated or squeezed parallel to the field polarization. In the later stages it evolves towards isotropization, which is always approached from the elongated shape. Thus, an initially squeezed distribution function first evolves towards an elongated shape and subsequently towards isotropization. The physical origin and the consequences of the reported features are discussed. In addition, a number of physical processes for which the theory demands the use of the described non-equilibrium distribution functions are briefly addressed.

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“…If two charged particles interact via Coulomb collision, they emit radiation, termed bremsstrahlung. [3][4][5][6][7][8][9] According to the Fokker-Planck or particle-in-cell simulations, the IBA is also calculated. [1] One of the main absorption mechanisms in laser-plasma interaction is electron-ion collisions (inverse bremsstrahlung).…”

Section: Introductionmentioning

confidence: 99%

“…[2] The linear and nonlinear absorptions have been investigated using different electron distribution functions. [3][4][5][6][7][8][9] According to the Fokker-Planck or particle-in-cell simulations, the IBA is also calculated. [10,11] In laser-plasma interactions, the electron distribution function can be considered Maxwellian, q-non-extensive, Kappa-distributed electrons and other distributions.…”

Section: Introductionmentioning

confidence: 99%

Calculation of the inverse bremsstrahlung absorption in unmagnetized plasmas

Farrashbandi

Eslami‐Kalantari

2019

Contributions to Plasma Physics

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Inverse bremsstrahlung is one important way to deliver laser energy to the plasma in inertial confinement fusion. In this article, we study the collisional absorption rate as obtained from the Fokker-Planck treatment of an unmagnetized plasma in harmonic laser field. The electron-ion collision rate is considered in the Krook approximation, and the electron distribution function is considered a Maxwellian function. We evaluate the inverse bremsstrahlung absorption near the irradiated plasma surface in the critical layer. We observe that absorption increases with shorter laser wavelength and lower electron temperatures. When the maximum electron velocity in the limit of q → 1 reaches infinity, the q-non-extensive distribution function reduces to the standard Maxwell-Boltzmann distribution. K E Y W O R D Sabsorption, collision, inertial confinement fusion, inverse bremsstrahlung, laser plasma

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Nonlinear inverse bremsstrahlung and highly anisotropic electron distributions

Cited by 17 publications

References 13 publications

Influence of a plasma medium on laser assisted radiative recombination

Influence of a plasma medium on laser assisted radiative recombination

Response of Piezoelectric Lead–Zirconate–Titanate to Hypervelocity Silver Particles

Calculation of the inverse bremsstrahlung absorption in unmagnetized plasmas

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