Jose Mendonca - Academia.edu (original) (raw)
Papers by Jose Mendonca
Springer Series in OPTICAL SCIENCES
ABSTRACT
arXiv: High Energy Physics - Theory, 2006
Withdrawn: A short-proof of the non-existence of quartic terms in the Lagrangian of Ue(1)xUg(1) i... more Withdrawn: A short-proof of the non-existence of quartic terms in the Lagrangian of Ue(1)xUg(1) is given in the Addendum of hep-th/0601166 (Europhys.Lett.85:59901,2009).
Journal of Physics B: Atomic, Molecular and Optical Physics
A general approach to equilibrium and oscillations in a turbulent Bose-Einstein condensate, valid... more A general approach to equilibrium and oscillations in a turbulent Bose-Einstein condensate, valid in the mean-field approximation, is proposed. Two different wave equations, describing the quasi-static equilibrium and the elementary excitations of the medium are derived. In particular, it is shown that a modified Thomas-Fermi equilibrium can be defined in the presence of an arbitrary spectrum of oscillations. The oscillating modes are also determined using Bogoliubov-de Gennes (BdG) equations, valid in different geometrical configurations, such as infinite, cylindrical and toroidal. The case of a non-homogenous density is considered, which includes the modified equilibrium profiles. A general form of dispersion relation for the elementary excitations is derived. Twisted phonons, carrying a finite amount of angular momentum, are shown to be a particular class of BdG modes. They were previously derived from fluid equations. Nonlinear analysis also shows that envelope dark solitons can exist, and correspond to a rarefaction of twisted phonons.
Physica Scripta
We develop a wave-kinetic description of acoustic-gravity (AG) waves in the atmosphere. In our pa... more 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.
Physical Review E
A general view is proposed on wave propagation in fluids and plasmas where the resonant interacti... more A general view is proposed on wave propagation in fluids and plasmas where the resonant interaction of monochromatic waves with quasiparticles is considered. A kinetic equation for quasiparticles is used to describe the broadband turbulence interacting with monochromatic waves. Resonant interactions occur when the phase velocity of the long wavelength monochromatic wave is nearly equal to the group velocity of short wavelength wave packets, or quasiparticles, associated with the turbulent spectrum. It is shown that quasiparticle Landau damping can take place, as well as quasiparticle beam instabilities, thus establishing a direct link between short and large wavelength perturbations of the medium. This link is distinct from the usual picture of direct and inverse energy cascades, and it can be used as a different paradigm for the fluid and plasma turbulence theories.
Physical Review E
The basic theory of laser propagation in hollow waveguides is considered in the context of laser-... more The basic theory of laser propagation in hollow waveguides is considered in the context of laser-plasma physics. The physical model of waves reflecting between the guide walls is used to show that there is a discrete series of modes, and to give the mode dispersion relation and losses in terms of a given reflectivity. The mathematical connection between this model and the solution of Maxwell's equations for lossless propagation in a cylinder is given. Thus the solutions for low loss propagation for any given reflectivity can be obtained, provided it is close to 1. Results are given using Fresnel reflectivity for perfect dielectric and finite conductivity waveguides. The relationship of the breakdown intensity in dielectric waveguides to known breakdown intensities is also derived. The practical implications for the guiding of intense laser pulses and the limitations of the model are discussed. The theory is shown to explain, at least qualitatively, a number of previous experimental results.
Physics Letters A
A description of the nonlinear coupling between intense neutrino fluxes and electrostatic electro... more A description of the nonlinear coupling between intense neutrino fluxes and electrostatic electron-cyclotron-harmonic and convection modes in a nonuniform magnetoplasma is presented. It is found that the electron waves can be parametrically excited on account of the free energy of the coherent neutrino fluxes. The growth rates of the corresponding three-wave decay and modulational interactions are obtained. The nonthermally excited electrostatic plasma waves arc associated with turbulent collision processes, which can be responsible for the anomalous absorption of the neutrino energy in supernova explosions.
Physics Letters A
The nonlinear propagation of an intense neutrino flux in an electron-positron plasma with equilib... more The nonlinear propagation of an intense neutrino flux in an electron-positron plasma with equilibrium density and magnetic field inhomogeneities is considered. It is found that the neutrinos are nonlinearly coupled with elect&static and electromagnetic disturbances due to weak Fermi interaction and ponderomotive forces. The process is governed dy a Klein-Gordon equation for the neutrino flux and a wave equation for the plasma oscillations in the presence of the ponberomotive force of the neutrinos. This pair of equations is then used to derive a nonlinear dispersion relation which e+hibits that nonthermal electrostatic and electromagnetic fluctuations are created on account of the energy density of the neu/trinos. The relevance of our investigation to the anomalous absorption of neutrinos in a nonuniform magnetized medium is pointed out.
Physics Letters A
It is shown that intense neutrino fluxes can nonlinearly generate elliptically polarized electrom... more It is shown that intense neutrino fluxes can nonlinearly generate elliptically polarized electromagnetic waves in ionized super-dense gases immersed in an external magnetic field. For this purpose, dispersion relations for obliquely (perpendicularly) propagating (with respect to the direction of the ambient magnetic field lines) helicons (extraordinary modes) influenced by the neutrino ponderomotive force are derived. The growth rates of the decay interactions are presented. These processes may contribute to the conservation of neutrino spins in supernova explosions.
Physics, Mar 18, 2013
Phonon lasing—coherent amplification of phonons by stimulated emission—has been achieved in a pur... more Phonon lasing—coherent amplification of phonons by stimulated emission—has been achieved in a purely acoustic analog of a three-level laser scheme.
Physical Review E, 2000
It is shown here that a straightforward procedure can be used to quantize the linearized equation... more It is shown here that a straightforward procedure can be used to quantize the linearized equations for an electromagnetic field in a plasma. This leads to a definition of an effective mass for the transverse photons, and a different one for the longitudinal photons, or plasmons. Both masses are simply proportional to the electron plasma density. A nonlinear perturbative analysis can also be used to extend the quantization procedure, in order to include the ponderomotive force effects. This leads to the definition of a photon charge operator. The mean value of this operator, for a quantum state with a photon occupation number equal to 1, is the equivalent charge of the photon in a plasma.
Physics of Fluids B: Plasma Physics, 1992
ABSTRACT
Shukla on the occasion of his 60th birthday on 7th July 2010. Padma is one of the most prominent ... more Shukla on the occasion of his 60th birthday on 7th July 2010. Padma is one of the most prominent and productive scientists in plasma physics and in neighboring fields, and has published more than 1300 papers in scientific journals. It has for some time been the aim of his friends to honor him on this occasion, and earlier this year we sent out invitations to distinguished scientists who have collaborated with Padma over the years. The response has been overwhelming, and we collected 43 manuscripts, covering a diverse range of topics in plasma physics, which are now published in this issue. We believe that these papers reflect some of the impact of Padma's research in plasma physics. Padma was born near Varanasi, India, where he received his education and first scientific schooling. He was later invited to Sweden, where he successfully received a doctorate in Physics under the supervision of Prof. Lennart Stenflo. This led to a long and successful career at the Ruhr-University Bochum, Germany, where he established his base. Padma's exceptionally productive career spans four decades and includes a diverse range of subjects in plasma physics and neighboring areas of physics, such as nonlinear interactions between plasmas and electromagnetic fields, relativistic laser-plasma interactions, dusty (complex) plasmas, drift waves and vortices in magnetized plasmas, magnetic confinement fusion, collective neutrinoplasma interactions and quantum effects in plasmas, to mention a few. For his scientific achievements, Padma has been awarded several prizes, including the Gay-Lussac/Humboldt Prize. He has been elected Foreign Member of the Royal Swedish Academy of Sciences and the Royal Swedish Academy of Engineering Sciences and Corresponding Fellow of the Royal Society of Edinburgh, Scotland. He has also received Doctor Honouris Causa degrees from the Russian Academy of Sciences and the Technical University of Lisbon, Portugal. Padma has always had the mentoring of students from the third world close to his heart. This has been accomplished by inviting and supervising PhD students and junior researchers to his group and to numerous workshops and summer schools at the Abdus Salam International Centre for Theoretical Physics in Trieste, Italy, as well as in Faro, Portugal and in Santorini, Greece. This training of young researchers has lead to the possibility for them to start their own independent careers and research groups in India, Pakistan, Egypt, Brazil and other places. Padma's work awarded him the 2005 American Physical Society Nicholson Medal for Human Outreach "For his prodigious and successful efforts in encouraging young scientists from underrepresented countries throughout the world, by his regular visits to their universities and by facilitating their participation in international meetings and workshops." It is a great privilege for us to know and work with Padma both as a colleague and as a friend. We wish Padma a very long and healthy life and hope that he will continue with many more years of success in science and to be a source of inspiration for future generations of scientists.
Springer Series in OPTICAL SCIENCES
ABSTRACT
arXiv: High Energy Physics - Theory, 2006
Withdrawn: A short-proof of the non-existence of quartic terms in the Lagrangian of Ue(1)xUg(1) i... more Withdrawn: A short-proof of the non-existence of quartic terms in the Lagrangian of Ue(1)xUg(1) is given in the Addendum of hep-th/0601166 (Europhys.Lett.85:59901,2009).
Journal of Physics B: Atomic, Molecular and Optical Physics
A general approach to equilibrium and oscillations in a turbulent Bose-Einstein condensate, valid... more A general approach to equilibrium and oscillations in a turbulent Bose-Einstein condensate, valid in the mean-field approximation, is proposed. Two different wave equations, describing the quasi-static equilibrium and the elementary excitations of the medium are derived. In particular, it is shown that a modified Thomas-Fermi equilibrium can be defined in the presence of an arbitrary spectrum of oscillations. The oscillating modes are also determined using Bogoliubov-de Gennes (BdG) equations, valid in different geometrical configurations, such as infinite, cylindrical and toroidal. The case of a non-homogenous density is considered, which includes the modified equilibrium profiles. A general form of dispersion relation for the elementary excitations is derived. Twisted phonons, carrying a finite amount of angular momentum, are shown to be a particular class of BdG modes. They were previously derived from fluid equations. Nonlinear analysis also shows that envelope dark solitons can exist, and correspond to a rarefaction of twisted phonons.
Physica Scripta
We develop a wave-kinetic description of acoustic-gravity (AG) waves in the atmosphere. In our pa... more 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.
Physical Review E
A general view is proposed on wave propagation in fluids and plasmas where the resonant interacti... more A general view is proposed on wave propagation in fluids and plasmas where the resonant interaction of monochromatic waves with quasiparticles is considered. A kinetic equation for quasiparticles is used to describe the broadband turbulence interacting with monochromatic waves. Resonant interactions occur when the phase velocity of the long wavelength monochromatic wave is nearly equal to the group velocity of short wavelength wave packets, or quasiparticles, associated with the turbulent spectrum. It is shown that quasiparticle Landau damping can take place, as well as quasiparticle beam instabilities, thus establishing a direct link between short and large wavelength perturbations of the medium. This link is distinct from the usual picture of direct and inverse energy cascades, and it can be used as a different paradigm for the fluid and plasma turbulence theories.
Physical Review E
The basic theory of laser propagation in hollow waveguides is considered in the context of laser-... more The basic theory of laser propagation in hollow waveguides is considered in the context of laser-plasma physics. The physical model of waves reflecting between the guide walls is used to show that there is a discrete series of modes, and to give the mode dispersion relation and losses in terms of a given reflectivity. The mathematical connection between this model and the solution of Maxwell's equations for lossless propagation in a cylinder is given. Thus the solutions for low loss propagation for any given reflectivity can be obtained, provided it is close to 1. Results are given using Fresnel reflectivity for perfect dielectric and finite conductivity waveguides. The relationship of the breakdown intensity in dielectric waveguides to known breakdown intensities is also derived. The practical implications for the guiding of intense laser pulses and the limitations of the model are discussed. The theory is shown to explain, at least qualitatively, a number of previous experimental results.
Physics Letters A
A description of the nonlinear coupling between intense neutrino fluxes and electrostatic electro... more A description of the nonlinear coupling between intense neutrino fluxes and electrostatic electron-cyclotron-harmonic and convection modes in a nonuniform magnetoplasma is presented. It is found that the electron waves can be parametrically excited on account of the free energy of the coherent neutrino fluxes. The growth rates of the corresponding three-wave decay and modulational interactions are obtained. The nonthermally excited electrostatic plasma waves arc associated with turbulent collision processes, which can be responsible for the anomalous absorption of the neutrino energy in supernova explosions.
Physics Letters A
The nonlinear propagation of an intense neutrino flux in an electron-positron plasma with equilib... more The nonlinear propagation of an intense neutrino flux in an electron-positron plasma with equilibrium density and magnetic field inhomogeneities is considered. It is found that the neutrinos are nonlinearly coupled with elect&static and electromagnetic disturbances due to weak Fermi interaction and ponderomotive forces. The process is governed dy a Klein-Gordon equation for the neutrino flux and a wave equation for the plasma oscillations in the presence of the ponberomotive force of the neutrinos. This pair of equations is then used to derive a nonlinear dispersion relation which e+hibits that nonthermal electrostatic and electromagnetic fluctuations are created on account of the energy density of the neu/trinos. The relevance of our investigation to the anomalous absorption of neutrinos in a nonuniform magnetized medium is pointed out.
Physics Letters A
It is shown that intense neutrino fluxes can nonlinearly generate elliptically polarized electrom... more It is shown that intense neutrino fluxes can nonlinearly generate elliptically polarized electromagnetic waves in ionized super-dense gases immersed in an external magnetic field. For this purpose, dispersion relations for obliquely (perpendicularly) propagating (with respect to the direction of the ambient magnetic field lines) helicons (extraordinary modes) influenced by the neutrino ponderomotive force are derived. The growth rates of the decay interactions are presented. These processes may contribute to the conservation of neutrino spins in supernova explosions.
Physics, Mar 18, 2013
Phonon lasing—coherent amplification of phonons by stimulated emission—has been achieved in a pur... more Phonon lasing—coherent amplification of phonons by stimulated emission—has been achieved in a purely acoustic analog of a three-level laser scheme.
Physical Review E, 2000
It is shown here that a straightforward procedure can be used to quantize the linearized equation... more It is shown here that a straightforward procedure can be used to quantize the linearized equations for an electromagnetic field in a plasma. This leads to a definition of an effective mass for the transverse photons, and a different one for the longitudinal photons, or plasmons. Both masses are simply proportional to the electron plasma density. A nonlinear perturbative analysis can also be used to extend the quantization procedure, in order to include the ponderomotive force effects. This leads to the definition of a photon charge operator. The mean value of this operator, for a quantum state with a photon occupation number equal to 1, is the equivalent charge of the photon in a plasma.
Physics of Fluids B: Plasma Physics, 1992
ABSTRACT
Shukla on the occasion of his 60th birthday on 7th July 2010. Padma is one of the most prominent ... more Shukla on the occasion of his 60th birthday on 7th July 2010. Padma is one of the most prominent and productive scientists in plasma physics and in neighboring fields, and has published more than 1300 papers in scientific journals. It has for some time been the aim of his friends to honor him on this occasion, and earlier this year we sent out invitations to distinguished scientists who have collaborated with Padma over the years. The response has been overwhelming, and we collected 43 manuscripts, covering a diverse range of topics in plasma physics, which are now published in this issue. We believe that these papers reflect some of the impact of Padma's research in plasma physics. Padma was born near Varanasi, India, where he received his education and first scientific schooling. He was later invited to Sweden, where he successfully received a doctorate in Physics under the supervision of Prof. Lennart Stenflo. This led to a long and successful career at the Ruhr-University Bochum, Germany, where he established his base. Padma's exceptionally productive career spans four decades and includes a diverse range of subjects in plasma physics and neighboring areas of physics, such as nonlinear interactions between plasmas and electromagnetic fields, relativistic laser-plasma interactions, dusty (complex) plasmas, drift waves and vortices in magnetized plasmas, magnetic confinement fusion, collective neutrinoplasma interactions and quantum effects in plasmas, to mention a few. For his scientific achievements, Padma has been awarded several prizes, including the Gay-Lussac/Humboldt Prize. He has been elected Foreign Member of the Royal Swedish Academy of Sciences and the Royal Swedish Academy of Engineering Sciences and Corresponding Fellow of the Royal Society of Edinburgh, Scotland. He has also received Doctor Honouris Causa degrees from the Russian Academy of Sciences and the Technical University of Lisbon, Portugal. Padma has always had the mentoring of students from the third world close to his heart. This has been accomplished by inviting and supervising PhD students and junior researchers to his group and to numerous workshops and summer schools at the Abdus Salam International Centre for Theoretical Physics in Trieste, Italy, as well as in Faro, Portugal and in Santorini, Greece. This training of young researchers has lead to the possibility for them to start their own independent careers and research groups in India, Pakistan, Egypt, Brazil and other places. Padma's work awarded him the 2005 American Physical Society Nicholson Medal for Human Outreach "For his prodigious and successful efforts in encouraging young scientists from underrepresented countries throughout the world, by his regular visits to their universities and by facilitating their participation in international meetings and workshops." It is a great privilege for us to know and work with Padma both as a colleague and as a friend. We wish Padma a very long and healthy life and hope that he will continue with many more years of success in science and to be a source of inspiration for future generations of scientists.