liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Stenflo, Lennart
Publications (10 of 77) Show all publications
Mendonca, J. T. & Stenflo, L. (2015). Acoustic-gravity waves in the atmosphere: from Zakharov equations to wave-kinetics. Physica Scripta, 90(5), 055001
Open this publication in new window or tab >>Acoustic-gravity waves in the atmosphere: from Zakharov equations to wave-kinetics
2015 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, no 5, p. 055001-Article in journal (Refereed) Published
Abstract [en]

We develop a wave-kinetic description of acoustic-gravity (AG) waves in the atmosphere. In our paper the high frequency spectrum of waves is described as a gas of quasi-particles. Starting from the Zakharov-type of equations, where coupling between fast and slow density perturbations is considered, we derive the corresponding wave-kinetic equations, written in terms of an appropriate Wigner function. This provides an alternative description for the nonlinear interaction between the two dispersion branches of the AG waves.

Place, publisher, year, edition, pages
IOP Publishing: Hybrid Open Access, 2015
Keywords
acoustic-gravity waves; Zakharov equations; Wigner function
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-120293 (URN)10.1088/0031-8949/90/5/055001 (DOI)000356498700016 ()
Note

Funding Agencies|International Space Science Institute in Bern (Switzerland)

Available from: 2015-07-24 Created: 2015-07-24 Last updated: 2017-12-04
Brodin, G. & Stenflo, L. (2015). Nonlinear wave interactions of kinetic sound waves. Annales Geophysicae, 33(8), 1007-1010
Open this publication in new window or tab >>Nonlinear wave interactions of kinetic sound waves
2015 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, no 8, p. 1007-1010Article in journal (Refereed) Published
Abstract [en]

We reconsider the nonlinear resonant interaction between three electrostatic waves in a magnetized plasma. The general coupling coefficients derived from kinetic theory are reduced here to the low-frequency limit. The main contribution to the coupling coefficient we find in this way agrees with the coefficient recently presented in Annales Geophysicae. But we also deduce another contribution which sometimes can be important, and which qualitatively agrees with that of an even more recent paper. We have thus demonstrated how results derived from fluid theory can be improved and generalized by means of kinetic theory. Possible extensions of our results are outlined.

Place, publisher, year, edition, pages
COPERNICUS GESELLSCHAFT MBH, 2015
Keywords
Magnetospheric physics (solar wind-magnetosphere interactions)
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-121769 (URN)10.5194/angeo-33-1007-2015 (DOI)000360651100007 ()
Available from: 2015-10-06 Created: 2015-10-05 Last updated: 2017-12-01
Brodin, G. & Stenflo, L. (2015). Three-wave coupling coefficients for perpendicular wave propagation in a magnetized plasma. Physics of Plasmas, 22(10), Article ID 104503.
Open this publication in new window or tab >>Three-wave coupling coefficients for perpendicular wave propagation in a magnetized plasma
2015 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, no 10, article id 104503Article in journal (Refereed) Published
Abstract [en]

The resonant interaction between three waves in a uniform magnetized plasma is reconsidered. Starting from previous kinetic expressions, we limit our investigation to waves propagating perpendicularly to the external magnetic field. It is shown that reliable results can only be obtained in the two-dimensional case, i.e., when the wave vectors have both x and y components. (C) 2015 AIP Publishing LLC.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-123160 (URN)10.1063/1.4934938 (DOI)000364403600128 ()
Available from: 2015-12-07 Created: 2015-12-04 Last updated: 2017-12-01
Stenflo, L. & Brodin, G. (2014). Collisional contribution to stimulated scattering in plasmas. Physics Letters A, 378(5-6), 549-550
Open this publication in new window or tab >>Collisional contribution to stimulated scattering in plasmas
2014 (English)In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 378, no 5-6, p. 549-550Article in journal (Refereed) Published
Abstract [en]

The influence of collisions on stimulated Brillouin scattering in magnetized plasmas is discussed. It is shown that new effects occur when the magnitude of the electron quiver velocity exceeds the electron thermal velocity.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Magnetized plasma; Stimulated scattering; Collisional effects
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-105252 (URN)10.1016/j.physleta.2013.12.027 (DOI)000330916300017 ()
Available from: 2014-03-14 Created: 2014-03-14 Last updated: 2017-12-05
Onishchenko, O. G., Horton, W., Pokhotelov, O. A. & Stenflo, L. (2014). Dust devil generation. Physica Scripta, 89(7), 075606
Open this publication in new window or tab >>Dust devil generation
2014 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, no 7, p. 075606-Article in journal (Refereed) Published
Abstract [en]

The equations describing axi-symmetric nonlinear internal gravity waves in an unstable atmosphere are derived. A hydrodynamic model of a dust devil generation mechanism in such an atmosphere is investigated. It is shown that in an unstably stratified atmosphere the convective plumes with poloidal motion can grow exponentially. Furthermore, it is demonstrated that these convective plumes in an atmosphere with weak large scale toroidal motion are unstable with respect to three-dimensional dust devil generation.

Place, publisher, year, edition, pages
IOP Publishing: Hybrid Open Access, 2014
Keywords
vortex structures; internal gravity waves; tornadoes; temperature gradients
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-111299 (URN)10.1088/0031-8949/89/7/075606 (DOI)000341561800028 ()
Note

Funding Agencies|International Space Science Institute in Bern (Switzerland); Russian Academy of Sciences [8, 22]; RFBR [14-05-00850]; NSF [0964692]; University of Aix-Marseille/CNRS; IMeRA Grant for Advanced Research

Available from: 2014-10-14 Created: 2014-10-14 Last updated: 2017-12-05
Karimov, A. R., Yu, M. Y. & Stenflo, L. (2014). Expansion of a cold non-neutral plasma slab. Physics of Plasmas, 21, 122304
Open this publication in new window or tab >>Expansion of a cold non-neutral plasma slab
2014 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 21, p. 122304-Article in journal (Refereed) Published
Abstract [en]

Expansion of the ion and electron fronts of a cold non-neutral plasma slab with a quasi-neutral core bounded by layers containing only ions is investigated analytically and exact solutions are obtained. It is found that on average, the plasma expansion time scales linearly with the initial inverse ion plasma frequency as well as the degree of charge imbalance, and no expansion occurs if the cold plasma slab is stationary and overall neutral. However, in both cases, there can exist prominent oscillations on the electron front.

National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113553 (URN)10.1063/1.4903879 (DOI)000347162700029 ()
Note

This work was supported by the National Natural Science Foundation of China (11205194, 11247007, 11374262), ITER-CN (2013GB104004), and the Open Fund of the State Key Laboratory of High Field Laser Physics at SIOM.

Available from: 2015-01-22 Created: 2015-01-22 Last updated: 2017-12-05
Brodin, G. & Stenflo, L. (2014). Large amplitude electron plasma oscillations. Physics Letters A, 378(22-23), 1632-1635
Open this publication in new window or tab >>Large amplitude electron plasma oscillations
2014 (English)In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 378, no 22-23, p. 1632-1635Article in journal (Refereed) Published
Abstract [en]

We consider a cold plasma in order to find new large-amplitude wave solutions in the long-wavelength limit. Accordingly we derive two generic coupled equations which describe the energy exchange between the electrostatic and electromagnetic waves. A new kind of quasi-periodic behavior is found. Our derivations may be considered as a prerequisite to extended studies of stimulated Raman scattering for cases where the wave amplitudes are so large that standard perturbation techniques are not applicable.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Large amplitude waves; Plasma oscillations; Parametric processes
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-108813 (URN)10.1016/j.physleta.2014.04.011 (DOI)000336868400008 ()
Available from: 2014-07-07 Created: 2014-07-06 Last updated: 2017-12-05
Brodin, G. & Stenflo, L. (2014). Nonlinear dynamics of large amplitude modes in a magnetized plasma. Physics of Plasmas, 21, 122301
Open this publication in new window or tab >>Nonlinear dynamics of large amplitude modes in a magnetized plasma
2014 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 21, p. 122301-Article in journal (Refereed) Published
Abstract [en]

We derive two equations describing the coupling between electromagnetic and electrostaticoscillations in one-dimensional geometry in a magnetized cold and non-relativistic plasma. The nonlinear interaction between the wave modes is studied numerically. The effects of the external magnetic field strength and the initial electromagneticpolarization are of particular interest here. New results can, thus, be identified.

National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113551 (URN)10.1063/1.4903326 (DOI)000347162700026 ()
Available from: 2015-01-22 Created: 2015-01-22 Last updated: 2017-12-05
Brodin, G. & Stenflo, L. (2014). Wave Generation in a Warm Magnetized Multi-Component Plasma. Contributions to Plasma Physics, 54(7), 623-625
Open this publication in new window or tab >>Wave Generation in a Warm Magnetized Multi-Component Plasma
2014 (English)In: Contributions to Plasma Physics, ISSN 0863-1042, E-ISSN 1521-3986, Vol. 54, no 7, p. 623-625Article in journal (Refereed) Published
Abstract [en]

The resonant interaction between three waves propagating perpendicularly to an external magnetic field in a plasma is considered. We present the explicit expressions for the three wave coupling coefficients of a warm multi-component plasma. The results of previous work on the generation of THz radiation by laser plasma interaction are significantly improved.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2014
Keywords
Parametric instabilities; THz radiation
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-110484 (URN)10.1002/ctpp.201300054 (DOI)000340499400001 ()
Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2017-12-05
Mendonca, J. T., Onishchenko, O. G., Pokhotelov, O. A. & Stenflo, L. (2014). Wave-kinetic description of atmospheric turbulence. Physica Scripta, 89, 125004
Open this publication in new window or tab >>Wave-kinetic description of atmospheric turbulence
2014 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, p. 125004-Article in journal (Refereed) Published
Abstract [en]

We propose a wave-kinetic description of atmospheric turbulence, where the turbulence spectrum is described as a gas of quasi-particles. We apply this description to the case of zonal structures in the atmosphere, which can be excited by internal gravity wave turbulence. A general expression for the instability growth rates is derived, and the particular example of a nearly mono-kinetic turbulent spectrum is discussed.

Keywords
atmospheric turbulence, wave-kinetic theory, internal gravity waves
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113554 (URN)10.1088/0031-8949/89/12/125004 (DOI)000347960500005 ()
Available from: 2015-01-22 Created: 2015-01-22 Last updated: 2017-12-05
Organisations

Search in DiVA

Show all publications