| 1. |
- Andersson, Joel, 1981-, et al.
(author)
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HIP-Densification of Alloy 718 and ATI 718Plus
- 2014
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In: 8th International Symposium on Superalloy 718 and Derivatives. - Hoboken, NJ, USA : John Wiley & Sons. - 9781119016809 - 9781119016854 ; , s. 425-436
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Conference paper (peer-reviewed)
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| 2. |
- Axberg, Stefan, et al.
(author)
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Lärobok i Militärteknik, vol. 9 : Teori och metod
- 2013. - 1
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Book (other academic/artistic)abstract
- Ämnet militärteknik utgår från att tekniska system är officerens arbetsredskap och att en förståelse för och kunskap om dessa verktyg är central för att kunna utöva professionen framgångsrikt. Denna nionde volym av Lärobok i Militärteknik, benämnd Teori och Metod, behandlar centrala begrepp, teorier och postulat samt metoder för värdering av teknik och består av ett antal texter författade av 16 forskare och lärare vid den militärtekniska avdelningen. Volymen riktar sig främst till de som inlett sin officersutbildning och utgörs till stora delar av ett kompilat av publicerade och opublicerade militärtekniska texter och kan sägas utgöra militärteknikens ”state of the art”.
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| 3. |
- Bengtsson, Bengt Å., et al.
(author)
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Fjärilar
- 2010. - 1
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In: Rödlistade arter i Sverige 2010. - Uppsala : Artdatabanken i samarbete med Naturvårdsverket. - 9789188506351 ; , s. 361-392
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Book chapter (other academic/artistic)
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| 4. |
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| 5. |
- Bingham, Robert, et al.
(author)
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Ion acceleration by Alfven waves on auroral field lines
- 2013
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In: Physica Scripta. - : Institute of Physics. - 0031-8949 .- 1402-4896. ; 87:5
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Journal article (peer-reviewed)abstract
- Observations of ion acceleration along auroral field lines at the boundary of the plasma sheet and tail lobe of the Earth show that the energy of the ions increases with decreasing density. The observations can be explained by ion acceleration through Landau resonance with kinetic Alfven waves (KAWs) such that k(A) . v(i) = omega(A), where k(A) is the wave vector, v(i) is the ion resonance velocity and omega(A) is the Alfven wave frequency. The ion resonance velocities are proportional to the Alfven velocity which increases with decreasing density. This is in agreement with the data if the process is occurring at the plasma sheet tail lobe boundary. A quasi-linear theory of ion acceleration by KAWs is presented. These ions propagate both down towards and away from the Earth. The paths of the Freja and Polar satellites indicate that the acceleration takes place between the two satellites, between 1Re and 5Re. The downward propagating ions develop a horseshoe-type of distribution which has a positive slope in the perpendicular direction. This type of distribution can produce intense lower hybrid wave activity, which is also observed. Finally, the filamentation of shear Alfven waves is considered. It may be responsible for large-scale density striations.
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| 6. |
- Bingham, Robert, et al.
(author)
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Solar coronal heating by plasma waves
- 2010
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In: Journal of Plasma Physics. - : Cambridge university. - 0022-3778 .- 1469-7807. ; 76:2, s. 135-158
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Journal article (peer-reviewed)abstract
- The solar coronal plasma is maintained at temperatures of millions of degrees, much hotter than the photosphere, which is at a temperature of just 6000 K. In this paper, the plasma particle heating based on the kinetic theory of wave–particle interactions involving kinetic Alfvén waves and lower-hybrid drift modes is presented. The solar coronal plasma is collisionless and therefore the heating must rely on turbulent wave heating models, such as lower-hybrid drift models at reconnection sites or the kinetic Alfvén waves. These turbulent wave modes are created by a variety of instabilities driven from below. The transition region at altitudes of about 2000 km is an important boundary chromosphere, since it separates the collision-dominated photosphere/chromosphere and the collisionless corona. The collisionless plasma of the corona is ideal for supporting kinetic wave–plasma interactions. Wave–particle interactions lead to anisotropic non-Maxwellian plasma distribution functions, which may be investigated by using spectral analysis procedures being developed at the present time.
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| 7. |
- Eliasson, Bengt, et al.
(author)
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Dispersion properties of electrostatic oscillations in quantum plasmas
- 2010
-
In: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 76, s. 7-17
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Journal article (peer-reviewed)abstract
- We present a derivation of the dispersion relation for electrostatic oscillations in a zero-temperature quantum plasma, in which degenerate electrons are governed by the Wigner equation, while non-degenerate ions follow the classical fluid equations. The Poisson equation determines the electrostatic wave potential. We consider parameters ranging from semiconductor plasmas to metallic plasmas and electron densities of compressed matter such as in laser compression schemes and dense astrophysical objects. Owing to the wave diffraction caused by overlapping electron wave function because of the Heisenberg uncertainty principle in dense plasmas, we have the possibility of Landau damping of the high-frequency electron plasma oscillations at large enough wavenumbers. The exact dispersion relations for the electron plasma oscillations are solved numerically and compared with the ones obtained by using approximate formulas for the electron susceptibility in the high- and low-frequency cases.
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| 8. |
- Eliasson, Bengt, et al.
(author)
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Full-scale simulation study of stimulated electromagnetic emissions: The first ten milliseconds
- 2010
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In: JOURNAL OF PLASMA PHYSICS. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 76, s. 369-375
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Journal article (peer-reviewed)abstract
- A full-scale numerical study is performed of the nonlinear interaction between a large-amplitude electromagnetic wave and the Earths ionosphere; and of the stimulated electromagnetic emission emerging from the turbulent layer, during the first 10 milliseconds after switch-on of the radio transmitter. The frequency spectra are downshifted in frequency and appear to emerge from a region somewhat below the cutoff of the O mode, which is characterized by Langmuir wave turbulence and localized Langmuir envelopes trapped in ion density cavities. The spectral features of escaping O-mode waves are very similar to those observed in experiments. The frequency components of Z-mode waves, trapped in the region between the O- and Z-mode cutoffs show strongly asymmetric and downshifted spectra.
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| 9. |
- Eliasson, Bengt, et al.
(author)
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Numerical investigation of the instability and nonlinear evolution of narrow-band directional ocean waves
- 2010
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In: Physical Review Letters. - New York : The American Physical Society. - 0031-9007 .- 1079-7114. ; 105:1, s. 014501-
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Journal article (peer-reviewed)abstract
- The instability and nonlinear evolution of directional ocean waves is investigated numerically by means of simulations of the governing kinetic equation for narrow-band surface waves. Our simulation results reveal the onset of the modulational instability for long-crested wave trains, which agrees well with recent large-scale experiments in wave basins, where it was found that narrower directional spectra lead to self-focusing of ocean waves and an enhanced probability of extreme events. We find that the modulational instability is nonlinearly saturated by a broadening of the wave spectrum, which leads to the stabilization of the water-wave system. Applications of our results to other fields of physics, such as nonlinear optics and plasma physics, are discussed.
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| 10. |
- Eliasson, Bengt
(author)
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Numerical simulations of the Fourier transformed Vlasov-Maxwell system in higher dimensions - Theory and applications
- 2010
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In: Transport theory and statistical physics. - : Taylor & Francis. - 0041-1450 .- 1532-2424. ; 39:5-7, s. 387-465
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Journal article (peer-reviewed)abstract
- We present a review of recent developments of simulations of the Vlasov-Maxwell system of equations using a Fourier transform method in velocity space. In this method, the distribution functions for electrons and ions are Fourier transformed in velocity space, and the resulting set of equations are solved numerically. In the original Vlasov equation, phase mixing may lead to an oscillatory behavior and sharp gradients of the distribution function in velocity space, which is problematic in simulations where it can lead to unphysical electric fields and instabilities and to the recurrence effect where parts of the initial condition recur in the simulation. The particle distribution function is in general smoother in the Fourier-transformed velocity space, which is desirable for the numerical approximations. By designing outflow boundary conditions in the Fourier-transformed velocity space, the highest oscillating terms are allowed to propagate out through the boundary and are removed from the calculations, thereby strongly reducing the numerical recurrence effect. The outflow boundary conditions in higher dimensions including electromagnetic effects are discussed. The Fourier transform method is also suitable to solve the Fourier-transformed Wigner equation, which is the quantum mechanical analogue of the Vlasov equation for classical particles.
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