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EROFEEV Vasily MESHCHERIAKOV Dmitry a) Laboratory of nonlinear physics

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A decay of electromagnetic wave quanta in a turbulent plasma during their interaction with Langmuir waves

a,b

a,c

IA&E SB RAS

EROFEEVVasily

MESHCHERIAKOV Dmitry

a) Laboratory of nonlinear physics

Institute of Automation and Electometry

Siberian Branch of Russian Academy

of Sciences

b) Novosibirsk State University

Physical Department

c) Novosibirsk State University

Department of Information Technologies

- A key objective of developing natural sciences consists in heightening the information content of conclusions regarding phenomena in surrounding world.
- The progress of theoretical physics in XX-th century has complied with this objective insufficiently well.
- An impressive illustration to this statement has been worked out by the plasma studies:

- Traditional viewpoint: Nonlinear phenomena in weakly turbulent plasmas conserve the total number of Langmuir wave quanta
- A.S Kompaneyets, Zh. Eksp. Teor. Fiz. 31, 876 (1956).
- L. M. Gorbunov, V. P. Silin, Sov. Phys. JETP 20, 135 (1965).
- V.N. Tsytovich, Sov. Phys. Uspekhi 15, 632 (1973)

- Alternative opinion: Langmuir waves quickly transmit their energy to bulk plasma electrons during a stochastic electron acceleration
- F.G. Bass, Ya.B. Fainberg and V.D. Shapiro, Sov. Phys. JETP 22, 230 (1966).

“Incarnations” of the ensemble method in plasma theory:

- BBGKY plasma kinetics
- Hydrodynamic modelling of nonlinear plasma phenomena
- Wave phase averaging
- Hamiltonian approaches to description of phenomena in a turbulent plasma
- …

- The picture of ensemble evolution strongly depends on the ensemble content:
- Differing ensembles exhibit diverging interference of their evolving statistic.
- A general practice in physical theorizing was to regard particular deductions on the interference of the ensemble statistics as a genuine laws of the system physical evolution.

Absence of full data on particle positions and

momentums

Impossibility to predict plasma behavior

during infinite time period

The main goal: to develop reliable scenario of plasma

evolution for as a longer period as possible

Careful separation of informational basis of the theory

from full (never known!) plasma information

Noncompliance of plasma ensemble

substitutions with above principle

- Dependence of final deductions regarding the physical laws of the plasma evolution on the lowest order approximation of the perturbation theory. Necessity of selecting the most rational choice of the lowest order approximation:
- First successive iterations of nonlinear perturbation expansion converge to conditional limit that depends on the theory leading order
- Differing conditional limits stands for varying scenarios of the plasma evolution

- Restrictions on appropriateness of certain mathematical procedures in intermediate calculations: Fourier and Laplace transformations are fraught with deviation of final theoretical deductions from objective physics of plasma evolution:
- In computing scenario of plasma evolution, one should use predominantly the data on current plasma state and on its relatively recent past
- Temporal Forier and Laplace transforms do not discriminate data on plasma states at remote periods of time

- Had the picture of ensemble evolution not depended on the ensemble content, one may have substantiated by ensemble variations the diversity of lowest order approximations.
- Variations of lowest order approximation within the practice of ensemble studies suppose appeals to differing ensembles; absence of dependence of plasma evolution picture on the theory leading order would have meant then the independence of the picture of the ensemble evolution on the ensemble content.

- It is necessary to gain existing practice of physical theorizing by creating new approaches that both refrain from traditional plasma ensemble substitutions and take proper account of the asymptotic nature of successive iterations.
- An approach of this type, Thecorrelation analysis of plasma kinetics, is created for studies of turbulent plasma phenomena.
- The revealing of other plasma contexts yielding any informative final theoretical conclusions and the developing of theoretical means for inferring respective conclusions should constitute an extremely important component of further plasma research.

Principles of getting high-informativeplasma kinetic scenarios: A REFRAIN FROM

THE PLASMA ENSEMBLE SUBSTITUTION

With refraining from the the plasma ensemble

averaging, one is forced to substitute the latter by a

contextually oriented averaging in phase space of

plasma particles. Particularly, the statistic of

distribution function is defined as a density of particles

within voluminous areas of -space:

The direct time integration discriminates the

indeterminate data on time remote plasma states

via the “phase mixing” within corresponding

nonlinear integrals

- The possibility of developing informative conclusions depends essentially on the theory expansion parameter. With expansion parameter , the most optimal order of the expansion is about . Up to this top level, the adding of extra orders leads to enlarging the time interval of reliability of respective plasma scenario. In the plasma turbulence case, the expansion parameter is
the ratio of typical wave damping rate to the width of

turbulence spectrum in natural frequencies , then conclusions on current plasma evolution up to -th order are reliable up to time delays of the order of

- Presumably, in other cases the expansion parameter should also constitute a ratio of two characteristic inverse times, with analogous estimation of the period of the scenario reliability.

The rate of wave

energy dissipation:

Here is the quanta density of electromagnetic waves with polarization

, is the natural frequency of the wave, and are the

components of wave collision integral :

,

is the nonlinear wave damping rate.

Comment: Total wave energy in the unit of plasma volume is given by

integral

- Wong et al.:
- A.Y. Wong and P.Y. Cheung, Phys. Rev.Lett. 52, 1222 (1984).
- P.Y. Cheung and A.Y. Wong, Phys. Rev.Lett. 55, 1880 (1985).
- M.D. McFarland and A.Y. Wong, Phys. Plasmas 4, 945 (1997).
- M.D. McFarland and A.Y. Wong, Phys. Rev. Lett. 84, 666 (2000).

- Vyacheslavov et al:
- L.N. Vyacheslavov et al.,
- Proc. of the IV-th International Workshop “Strong Microwaves in Plasmas,” Nizhny Novgorod, Inst. of Applied Physics, 1999, ed. A.G. Litvak (Nauka, Moscow, 2000) Vol. 2, p. 405
- L.N. Vyacheslavov et al., JETP Letters 75, 41 (2002).
- L.N. Vyacheslavov et al., PPCF 44, B279 (2002).

- Benford et al:
- D. Levron, G. Benford and D. Tzach, Phys. Rev. Lett. 58, 1336 (1987).
- G. Benford, X. Zhai and D. Levron, Phys. Fluids B 3, 560 (1991).
- G. Benford and X.L. Zhai, Phys. Fluids B 5, 1914 (1993).

Full plasma description = Klimontovich-Dupree equation + Maxwell equations

Microdistribution (Klimontovich):

The microdistribution cannot be rendered as a constructive notion of the theory: it depends essentially on the positions and momenta of all plasma particles.

Distribution function:

An infinite hierarchy of evolution equations for multipoint correlation functions:

- Distribution function is advanced in time by the two-point correlation function
- The two-point correlation functionis advanced in time by the three-point correlation function
- …
- After the hierarchy truncation at a reasonable order, the system can be reduced to simultaneous evolution equations of distribution function and two-point correlation function

- The characteristic time of plasma and spectrum evolution, , is great compared to inverse spectrum width in natural frequences .
- In collision integral of plasma particles, the effect of two-point correlation function can be expressed in terms of the two-time correlation function
- The two-point correlation functiondrives via Maxwell equations the two-time correlation function
- Within domain , the evolution equation of two-time correlation function can be directly integrated: the function can be expressed in terms of wave spectral density .
- The resulting expression (of the two-time correlation function) can be used for obtaining time derivatives of distribution functions and spectral density