| 1. |
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| 2. |
- Anders, Berntson, et al.
(författare)
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Self-phase modulation in dispersion compensated optical fibre transmission systems
- 1996
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 130:1-3, s. 153-162
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Tidskriftsartikel (refereegranskat)abstract
- An analysis is made of the influence of self-phase modulation on optical fibre communication systems where the chromatic dispersion is compensated for by a dispersion compensation fibre. In particular we derive a simple and useful expression for the optimal fibre length in the presence of nonlinearities.
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| 3. |
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| 4. |
- Anderson, Dan, 1943, et al.
(författare)
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Approximate solution of a Thomas-Fermi model equation for bulk self-gravitating stellar objects in two dimensions
- 2017
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Ingår i: European journal of physics. - : Institute of Physics (IOP). - 0143-0807 .- 1361-6404. ; 38, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Direct variational methods are used to find simple approximate solutions of the Thomas–Fermi equations describing the properties of self-gravitating radially symmetric stellar objects both in the non-relativistic and ultra-relativistic cases. The approximate solutions are compared and shown to be in good agreement with exact and numerically obtained solutions.
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| 5. |
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| 6. |
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| 7. |
- Anderson, Dan, 1943, et al.
(författare)
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Galerkin approach to approximate solutions of some nonlinear oscillator equations
- 2010
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Ingår i: American Journal of Physics. - : American Association of Physics Teachers (AAPT). - 0002-9505 .- 1943-2909. ; 78:9, s. 920-924
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Tidskriftsartikel (refereegranskat)abstract
- An analysis based on the Galerkin method is given of some nonlinear oscillator equations that have been analyzed by several other methods, including harmonic balance and direct variational methods. The present analysis is shown to provide simple yet accurate approximate solutions of these nonlinear equations and illustrates the usefulness and the power of the Galerkin method. (C) 2010 American Association of Physics Teachers. [DOI: 10.1119/1.3429974]
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| 8. |
- Anderson, Dan, 1943, et al.
(författare)
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Interaction between two partially incoherent soliton stripes
- 2008
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 281:14, s. 3919-3923
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Tidskriftsartikel (refereegranskat)abstract
- A detailed analysis is made of the mutual interaction of two, initially well separated, partially incoherent solitons in a nonlinear Kerr medium. Explicit expressions are obtained describing the influence of partial incoherence on the subsequent dynamics of the solitons. In particular it is shown that as the degree of incoherence increases, the character of the interaction may change between attractive and repulsive behavior (or vice versa). Furthermore, it is found that this dependence is not always monotonous. © 2008 Elsevier B.V. All rights reserved.
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| 9. |
- Anderson, Dan, 1943, et al.
(författare)
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Introduction to direct variational and moment methods and an application to the Child-Langmuir law
- 2015
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Ingår i: European Journal of Physics. - : IOP Publishing. - 1361-6404 .- 0143-0807. ; 2015:36, s. 065032-
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Tidskriftsartikel (refereegranskat)abstract
- A short introduction is given of direct variational methods and its relation to Galerkin and moment methods, all flexible and powerful approaches for finding approximate solutions of difficult physical equations. A pedagogicalapplication of moment methods is given to the physically and technically important Child–Langmuir law in electron physics. The analysis is shown to provide simple, yet accurate, approximate solutions of the two-dimensionalproblem (a problem which does not allow an exact analytical solution)and illustrates the usefulness and the power of moment methods.
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| 10. |
- Anderson, Dan, 1943, et al.
(författare)
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Microwave breakdown in RF devices
- 2006
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Ingår i: 33rd European Physical Society Conference on Plasma Physics, Rome, June 19-23, 2006. ; , s. 429-
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Konferensbidrag (refereegranskat)
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| 11. |
- Anderson, Dan, 1943, et al.
(författare)
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Modulational instabilities of partially incoherent light
- 2004
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Ingår i: Proceedings of "Nonlinear Guided Waves and Their Applications", March 28-31 2004, Toronto, Canada. - 9781557528209 ; , s. paper TuC32-
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Konferensbidrag (refereegranskat)
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| 12. |
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| 13. |
- Anderson, Dan, 1943, et al.
(författare)
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Parabolic similarity solutions of the Nonlinear Schrödinger and Wigner-Moyal equations
- 2008
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Ingår i: in Proceedings of SIAM Conference on Nonlinear Waves and Coherent Structures, July 21-24, 2008, Rome, Italy, Society for Industrial and Applied Mathematics (SIAM), Philadelphia, PA, USA. ; , s. 56-
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Konferensbidrag (refereegranskat)
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| 14. |
- Anderson, Dan, 1943, et al.
(författare)
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The least uncomfortable journey from A to B
- 2016
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Ingår i: American Journal of Physics. - : American Association of Physics Teachers (AAPT). - 0002-9505 .- 1943-2909. ; 84:9, s. 690-695
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Tidskriftsartikel (refereegranskat)abstract
- A short introduction is given about direct variational methods and their relation to Galerkin and moment methods, all flexible and powerful approaches for finding approximate solutions to difficult physicalequations. An application of these methods is given in the form of the variational problem of minimizing the discomfort experienced during different journeys, between two fixed horizontal points while keeping the travel time constant. The analysis is shown to provide simple, yet accurate, approximate solutions of the problem and illustrates the usefulness and the power of direct variational and moment methods. It also demonstrates the problem of a priori assessing the accuracy of the approximate solutions and illustrates that the variational solution does not necessarily provide a more accurate solution than that obtained by moment methods.
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| 15. |
- Anderson, Dan, 1943, et al.
(författare)
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The optimal journey from A to B
- 2008
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Ingår i: American Journal of Physics. ; 76:9, s. 863-866
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Tidskriftsartikel (refereegranskat)
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Armiens, C., et al.
(författare)
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Detection of multipaction using AM signals
- 2005
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Ingår i: Proc. 5th International Workshop on Multipactor, Corona and Passive Intermodulation, September 12 – 14, 2005, ESTEC, Noordwijk, The Netherlands, In: Space RF Hardware (MULCOPIM' 2005). ; , s. 143-149
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Konferensbidrag (refereegranskat)
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| 20. |
- Boyer, Gilbert, et al.
(författare)
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Four-wave mixing of femtosecond pump-probe pulses in optical fibers
- 1999
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Ingår i: Nonlinear Guided Waves and Their Applications.
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Konferensbidrag (refereegranskat)abstract
- The nonlinear propagation of a pump-probe pulse pair in an optical fiber has been extensively studied both experimentally, numerically and theoretically. In particular, it has been shown that the probe can attain a spectral shift under the influence of cross-phase modulation (XPM) from the pump, an effect having important applications in e. g. optical switching and demultiplexing.
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| 21. |
- Buyanova, M., et al.
(författare)
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Different saturation regimes of multipactor between parallel metal plates
- 2008
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Ingår i: Proceedings of the 7th International Workshop “Strong microwaves: Sources and Applications, Nizhny Novgorod, Russia, July 27 – Aug. 2, 2008, Institute of Applied Physics, Russian Academy of Sciences. ; :paper T41, s. 143-
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Konferensbidrag (refereegranskat)
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| 22. |
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| 23. |
- Buyanova, M., et al.
(författare)
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Influence of secondary emission yield on the saturation of two-sided multipactor
- 2008
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Ingår i: MULCOPIM08, 23-26 September 2008, Valencia, Spain, European Space Agency, Nordwijk, The Netherlands, available on CD. ; , s. paper MP5-6
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Konferensbidrag (refereegranskat)
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| 24. |
- Buyanova, M., et al.
(författare)
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Influence of secondary emission yield on the saturation properties of multipactor discharges between two parallel metal plates
- 2010
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 17:4, s. 043504 -
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Tidskriftsartikel (refereegranskat)abstract
- A detailed numerical simulation analysis is made of the saturation stage of multipactor discharges between two infinite parallel metal plates in vacuum exposed to a rf voltage. The main physical effect causing saturation of the multipactor discharge is increased space charge, as the electron density becomes large. It is found that the properties of the saturation stage depend crucially on the value of the secondary emission yield of the metal surfaces. Below a certain threshold value, the discharge has a two-sided character, but at this threshold the discharge makes an abrupt transition into two decoupled single-sided multipactor discharges containing significantly increased electron densities. The result of the numerical simulations gives a good picture of the saturation properties of the multipactor discharge and is also supplemented by an approximate analytical investigation that highlights and explains the characteristic properties of the observed saturation behavior.
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| 25. |
- Buyanova, M., et al.
(författare)
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Multi-Phase Regimes of Multipactor Breakdown
- 2005
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Ingår i: Proc. 5th International Workshop on Multipactor, Corona and Passive Intermodulation, September 12 – 14, 2005, ESTEC, Noordwijk, The Netherlands, In: Space RF Hardware (MULCOPIM' 2005). ; , s. 135-142
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Konferensbidrag (refereegranskat)
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| 26. |
- Bäckström, Mats G., et al.
(författare)
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Can intentional electrical discharges be used for HPM protection?
- 2011
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Ingår i: 2011 IEEE International Symposium on Electromagnetic Compatibility, EMC 2011; Long Beach, CA; 14 August 2011 through 19 August 2011. - 1077-4076. ; , s. 752-757
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Konferensbidrag (refereegranskat)abstract
- The possibility to protect electronics against High Power Microwaves (HPM) using an intentional electrical discharge triggered by the HPM pulse has been investigated. The case considered is a resonant slot, located e.g. in an antenna array or in a Frequency Selective Surface (FSS). The reduction of the pulse energy transmitted through the slot is regarded to be the most important parameter of merit. Experimental and theoretical research showed that a spark in the middle of a 46.3 0.1 mm resonant slot, induced by the incident HPM-pulse, gave a reduction of the transmitted pulse energy of about 24 dB. The studies showed that the investigated approach can provide a quite good level of protection that at least reduces the requirements on additional protection components such as limiters integrated in receivers located behind the slot. In order to achieve a sufficiently strong enhancement of the electric field to initiate breakdown in wide slots one presumably has to introduce a small pointed gap in the middle of the slot. This may in turn require that a radioactive sample is located close to the gap in order to produce a sufficient number of seed electrons necessary for triggering the discharge. © 2011 IEEE.
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| 27. |
- Cattani, F., et al.
(författare)
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Co-propagating Bose-Einstein condensates and electromagnetic radiation: Emission of mutually localized structures
- 2011
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 83:1, s. 013608-
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the details of the formation of mutually guided and localized structures of co-propagating coherent electromagnetic radiation and a Bose-Einstein condensate (BEC). In the limit of zero temperature and large detuning, we have used a semiclassical model based on Maxwell equations coupled to the Schrodinger equation which includes the back action of the atoms on the radiation. Following numerically the two systems, we have found that a variety of effects can be displayed depending on the initial conditions: The formation of single-hump mutually guided structures of atoms and radiation seems to be only one of the possible outcomes of the interaction. Other effects we have observed via numerical simulations are, for instance, the creation of atom-laser solitarylike structures which are then symmetrically ejected from the initial central peak or similar symmetrical structures trapped in a bound state and thus oscillating about the central point in a way somehow reminiscent of purely nonlinear optics effect.
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| 28. |
- Cattani, F., et al.
(författare)
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Co-propagating Bose-Einstein condensates and electromagnetic radiation: formation of mutually localized structures
- 2010
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 1361-6455 .- 0953-4075. ; 43:8
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Tidskriftsartikel (refereegranskat)abstract
- A semi-classical model is derived for describing the interaction between coherent electromagnetic radiation and a Bose-Einstein condensate in the limit of zero temperature, including the back action of the atoms on the radiation. This model is used to analyse the problem of the self-consistent evolution of a laser beam and a BEC atomic beam. The mutual propagation is studied numerically and demonstrates not only the possibility of a stationary regime of mutual guiding, but also of generating a collapse-like phenomenon.
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| 29. |
- Cattani, F., et al.
(författare)
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Interacting laser and Bose-Einstein-condensate atomic beams: Mutual guiding structures
- 2010
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 81:4, s. 043623 -
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Tidskriftsartikel (refereegranskat)abstract
- A basic set of equations describing the interaction of a Bose-Einstein condensate (BEC) with a laser field is derived based on a semiclassical model and applied to the problem of mutual guiding of laser and BEC atomic beams. Within this framework we have studied stationary spatially localized solutions of the nonlinear system which describe possible laser and BEC atomic beam guiding and have shown their stability as well. It is also shown that a self-guiding effect can be realized through both single-and multiple-scaled structures of a BEC atomic and a laser beam.
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| 30. |
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| 31. |
- Cattani, F., et al.
(författare)
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Multihump soliton-like structures in interactions of lasers and Bose-Einstein condensates
- 2011
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Ingår i: Europhysics Letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 94:5, s. 53003-
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made of multihump and periodic solutions of the semiclassical coupled equations describing laser radiation copropagating with a Bose-Einstein condensate. Solutions reminiscent of optical vector solitons have been found and have been used to gain understanding of the dynamics observed in the numerical simulations, in particular to shed light on the phenomenon of jet emission from a condensate interacting with a laser.
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| 32. |
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| 33. |
- Desaix, M., et al.
(författare)
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Nonlinear Schrödinger solitons with non-zero velocities emerging from real symmetric initial conditions
- 2008
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Ingår i: in Proceedings of SIAM Conference on Nonlinear Waves and Coherent Structures, July 21-24, 2008, Rome, Italy, Society for Industrial and Applied Mathematics (SIAM), Philadelphia, PA, USA. ; , s. 51-
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Konferensbidrag (refereegranskat)
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| 34. |
- Desaix, M., et al.
(författare)
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Nonlinear Schrödinger Solitons with non-zero velocities emerging from real symmetric initial conditions
- 2008
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 1106, s. 299-303
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Solutions of the nonlinear Schrodinger equation for initial conditions in the form of two separated sech-shaped in-phase pulses are analyzed. It is found that this initial condition, with appropriate amplitude, may give rise to, not only stationary solitons, but also to symmetrically separating soli- tons, if the initial distance of separation is large enough. The condition for the generation of a separating soliton pair is derived from the Zakharov-Shabat eigenvalue problem using a variational approach.
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| 35. |
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Fedele, R., et al.
(författare)
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How the coherent instabilities of an intense high energy charged particle beam in the presence of nonlocal effects can be explained within the context of the Madelung fluid description
- 2006
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Ingår i: European Physical Journal B. - : Springer Science and Business Media LLC. - 1434-6028 .- 1434-6036. ; B49:3, s. 275-281
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Tidskriftsartikel (refereegranskat)abstract
- A hydrodynamical description of coherent instabilities that take place in the longitudinal dynamics of a charged-particle coasting beam in a high-energy accelerating machine is presented. This is done within the framework of the Madelung fluid picture provided by the Thermal Wave Model. The well known coherent instability charts in the complex plane of the longitudinal coupling impedance for monochromatic beams are recovered. The results are also interpreted in terms of the deterministic approach to modulational instability analysis usually given for monochromatic large amplitude wave propagation governed by the nonlinear Schrodinger equation. The instability analysis is then extended to a non-monochromatic coasting beam with a given thermal equilibrium distribution, thought of as a statistical ensemble of monochromatic incoherent coasting beams ("white" beam). In this hydrodynamical framework, the phenomenon of Landau damping is predicted without using any kinetic equation governing the phase space evolution of the system.
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| 41. |
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| 42. |
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| 43. |
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Hall, Björn, 1973, et al.
(författare)
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Pump-probe collision in optical fibers : Four-wave-mixing induced frequency jump
- 2001
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - : Optical Society of America (OSA). - 0740-3224 .- 1520-8540. ; 18:11, s. 1652-1658
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made of ultrafast pump-probe pulse collisions near the zero-dispersion wavelength in an optical single-mode fiber. A steplike probe frequency shift is observed when the pump power is gradually increased. The magnitude of this frequency jump is shown to depend on the phase difference between the pulses. This new effect is investigated numerically and experimentally and is attributed to four-wave mixing.
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| 48. |
- Hansson, Tobias, 1983, et al.
(författare)
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Generalized dressing method for nonlinear evolution equations describing partially coherent wave propagation in noninstantaneous Kerr media
- 2011
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Ingår i: Physical Review E. - 2470-0045 .- 2470-0053. ; 84:5, s. 056601-
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Tidskriftsartikel (refereegranskat)abstract
- A generalized dressing method is presented for integration of the nonlinear evolution equation of the coherent density function describing partially coherent wave propagation in a noninstantaneous Kerr media. As an example an exact, partially coherent multisource N-soliton solution is derived. It is also demonstrated how this method is applicable for construction of solutions to the equivalent coupled system of nonlinear Schrodinger equations of the self-consistent multimode theory.
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| 49. |
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| 50. |
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