Author: Robert J. PapaPublisher:
ISBN:
Category : Coulomb excitation
Languages : en
Pages : 68
Book Description
Wave Propagation in a Hot Magnetoplasma with Coulomb Collisions
Author: Robert J. PapaPublisher:
ISBN:
Category : Coulomb excitation
Languages : en
Pages : 68
Book Description
Wave Propagation in a Warm Magnetoplasma with Coulomb Interactions
Author: Robert J. PapaPublisher:
ISBN:
Category : Ionosphere
Languages : en
Pages : 100
Book Description
Electromagnetic waves propagating through partially ionized gases can be severely attenuated and suffer distortion. This has important consequences in the design of any communication and radar system in which waves must propagate through an intervening plasma medium, such as in reentry communications and ionospheric propagation. In this report, formulas are derived that can predict such wave attenuation characteristics more accurately and for a wider range of plasma conditions than already existing theories. The conventional Appleton-Hartree equation used in ionospheric propagation studies gives the index of refraction of a wave travelling through a plasma in a magnetic field in terms of the properties of the plasma. This conventional Appleton-Hartree formula neglects important effects such as the random thermal motion of the particles, which can cause nonlocal effects. Also, the energy dependence of the electron-neutral collision frequency can alter the nature of the wave attenuation process. In the report, a generalization of the Appleton-Hartree equation is made to include these effects. A kinetic equation is solved which includes the effects of energy-dependent electron-neutral collisions, Coulomb encounters and spatial dispersion. The perturbation method used in solving the kinetic equation assumes that the effects of electron-neutral collisions and Coulomb encounters are dominant, and spatial dispersion effects are weak.
Wave Propagation in a Hot Magnetoplasma with Coulomb Collisions
Author: Robert J. PapaWave Propagation in a Hot Magnetoplasma with Velocity Dependent Collision Frequencies and Coulomb Encounters
Author: Robert John PapaTheory of Electromagnetic Wave Propagation in a Hot Magnetoplasma
Author: Robert J. PapaPublisher:
ISBN:
Category : Antennas (Electronic)
Languages : en
Pages : 0
Book Description
A brief discussion is given of the physical processes that occur in a hot magnetoplasma, and the results are compared to a cold plasma model. The conventional linearization of the Boltzmann equation is discussed, where the electron distribution function is expanded in terms of a small parameter proportional to the externally imposed electric field. Particle collisions are described by a relaxation model for the electron-neutral collision integral. The plasma is assumed to be Lorentzian, so that Coulomb collisions and ion motion are both neglected. Explicit expressions for the components of the conductivity tensor are given in Cartesian coordinates and in the principal coordinate system in which the conductivity tensor is symmetric. By asymptotically expanding the components of the conductivity tensor, it is shown how the dispersion relation determining the index of refraction becomes a relatively simple cubic equation. The Clemmow-Mullaly-Allis diagram is discussed for a warm plasma. Finally, the derivation of the radiation resistance of a short antenna in a hot, isotropic plasma is carried out in detail. (Author)
Numerical Solution of the Dispersion Relations for a Hot Magnetoplasma with Collisions
Author: Robert J. PapaPublisher:
ISBN:
Category : Dispersion relations
Languages : en
Pages : 48
Book Description
Detailed numerical studies have been made on the dispersion relations for electromagnetic waves propagating in partially ionized gases immersed in a dc magnetic field. Accurate values of the attenuation constant and phase shift are needed in the design of radio communications systems where waves must propagate through an ionized gas (such as in reentry communications systems), in the design of radar jamming devices used during missile reentry, and in the analytical study of ionospheric propagation phenomena. The numerical solution of the dispersion relations enable the effects of collisionless wave damping, velocity-dependent electron-neutral collisions, and Coulomb encounters to be studied. The attenuation and phase shift of waves propagating through a plasma are dependent upon the signal frequency, plasma temperature, plasma density, degree of ionization, and cross sections for electron scattering. Graphs are presented which enable attenuation constants and phase shifts to be readily evaluated for a very wide range of possible plasma conditions. (Author).
Theory of Electromagnetic Wave Propagation in a Hot Magnetoplasma
Author: Robert J. PapaPublisher:
ISBN:
Category : Antennas
Languages : en
Pages : 74
Book Description
A brief discussion is given of the physical processes that occur in a hot magnetoplasma, and the results are compared to a cold plasma model. The conventional linearization of the Boltzmann equation is discussed, where the electron distribution function is expanded in terms of a small parameter proportional to the externally imposed electric field. Particle collisions are described by a relaxation model for the electron-neutral collision integral. The plasma is assumed to be Lorentzian, so that Coulomb collisions and ion motion are both neglected. Explicit expressions for the components of the conductivity tensor are given in Cartesian coordinates and in the principal coordinate system in which the conductivity tensor is symmetric. By asymptotically expanding the components of the conductivity tensor, it is shown how the dispersion relation determining the index of refraction becomes a relatively simple cubic equation. The Clemmow-Mullaly-Allis diagram is discussed for a warm plasma. Finally, the derivation of the radiation resistance of a short antenna in a hot, isotropic plasma is carried out in detail. (Author).
Wave Propagation in a Warm Magnetoplasma with Coulomb Interactions
Author: Robert J. PapaPublisher:
ISBN:
Category : Ionosphere
Languages : en
Pages : 0
Book Description
Electromagnetic waves propagating through partially ionized gases can be severely attenuated and suffer distortion. This has important consequences in the design of any communication and radar system in which waves must propagate through an intervening plasma medium, such as in reentry communications and ionospheric propagation. In this report, formulas are derived that can predict such wave attenuation characteristics more accurately and for a wider range of plasma conditions than already existing theories. The conventional Appleton-Hartree equation used in ionospheric propagation studies gives the index of refraction of a wave travelling through a plasma in a magnetic field in terms of the properties of the plasma. This conventional Appleton-Hartree formula neglects important effects such as the random thermal motion of the particles, which can cause nonlocal effects. Also, the energy dependence of the electron-neutral collision frequency can alter the nature of the wave attenuation process. In the report, a generalization of the Appleton-Hartree equation is made to include these effects. A kinetic equation is solved which includes the effects of energy-dependent electron-neutral collisions, Coulomb encounters and spatial dispersion. The perturbation method used in solving the kinetic equation assumes that the effects of electron-neutral collisions and Coulomb encounters are dominant, and spatial dispersion effects are weak.
Collisional Effects on Waves in a Magnetoplasma
Author: John Quayle HowellPublisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 194
Book Description
A new class of collision-dependent electron waves is found in a non-Maxwellian Lorentz magnetoplasma, and it is shown that these waves may be driven unstable by electron-neutral collisions. The Boltzmann equation with collision integral is solved, assuming propagation either parallel or perpendicular to the magnetic field. Both conductivity tensors are derived and put in a form useful for numerical calculations. The full set of Maxwell's equations is then used to derive the dispersion relations for both directions of propagation. The dispersion relations are initially solved for a monoenergetic electron distribution function and following that a distribution with a peak of nonzero halfwidth is treated. Some consideration is also given to a Maxwellian distribution both with and without a bump on the tail. As an example of propagation parallel to the magnetic field, transverse electromagnetic or whistler waves are considered. (Author).
Author: John Q. Howell