Collective excitations in strongly coupled ultra-relativistic plasmas (original) (raw)
Related papers
Collective cyclotron motion of the relativistic plasma in graphene
2008
We present a theory of the finite temperature thermo-electric response functions of graphene in the hydrodynamic regime where electron-electron collisions dominate the scattering. In moderate magnetic fields, the Dirac particles undergo a collective cyclotron motion with a temperaturedependent relativistic cyclotron frequency proportional to the net charge density of the Dirac plasma. In contrast to the undamped cyclotron pole in Galilean-invariant systems (Kohn's theorem), here there is a finite damping induced by collisions between the counter-propagating particles and holes. This cyclotron motion shows up as a damped pole in the frequency dependent conductivities, and should be readily detectable in microwave measurements at room temperature. We also compute the large Nernst signal in the hydrodynamic regime which is significantly bigger than in ordinary metals.
Dispersion relations in ultradegenerate relativistic plasmas
Physical Review D, 2000
The propagation of excitation modes in a relativistic ultradegenerate plasma is modified by their interactions with the medium. These modifications can be computed by evaluating their on-shell self-energy, which gives (gaugeindependent) dispersion relations. For modes with momentum close to the Fermi momentum, the one-loop fermion self-energy is dominated by a diagram with a soft photon in the loop. We find the one-loop dispersion relations for quasiparticles and antiquasiparticles, which behave differently as a consequence of their very different phase-space restrictions when they scatter with the electrons of the Fermi sea. In a relativistic system, the unscreened magnetic interactions spoil the normal Fermi liquid behavior of the plasma. For small values of the Fermi velocity, we recover the non-relativistic dispersion relations of condensed matter systems.
Collective modes of ultra-relativistic magnetoactive electron plasma
Physica Scripta, 2007
Collective modes of ultra-relativistic electron plasma embedded in an ambient weak magnetic field are derived. Employing Maxwell equations in the four-dimensional Minkowski space and using the Vlasov model, polarization tensor is calculated and dispersion relations are obtained for both parallel and perpendicular propagations in the temporal axial gauge. Some interesting limiting cases are also discussed.
Physical review, 2017
Understanding the transport properties of charged particle beams is important not only from a fundamental point of view but also due to its relevance in a variety of applications. A theoretical model is established in this article, to model the interaction of a tenuous positively charged ion beam with an ultradense quantum electron-ion plasma, by employing a rigorous relativistic quantum-hydrodynamic (fluid plasma) electrostatic model proposed in McKerr et al. [M. McKerr, F. Haas, and I. Kourakis, Phys. Rev. E 90, 033112 (2014)]. A nonlinear analysis is carried out to elucidate the propagation characteristics and the existence conditions of large amplitude electrostatic solitary waves propagating in the plasma in the presence of the beam. Anticipating stationary profile excitations, a pseudomechanical energy balance formalism is adopted to reduce the fluid evolution equation to an ordinary differential equation. Exact solutions are thus obtained numerically, predicting localized excitations (pulses) for all of the plasma state variables, in response to an electrostatic potential disturbance. An ambipolar electric field form is also obtained. Thorough analysis of the reality conditions for all variables is undertaken in order to determine the range of allowed values for the solitonic pulse speed and how it varies as a function of the beam characteristics (beam velocity and density).
Solid State Communications, 2009
Electrons in graphene, behaving as massless relativistic Dirac particles, provide a new perspective on the relation between condensed matter and high-energy physics. We discuss atomic collapse, a novel state of superheavy atoms stripped of their discrete energy levels, which are transformed into resonant states. Charge impurities in graphene provide a convenient condensed matter system in which this effect can be explored. Relativistic dynamics also manifests itself in another system, graphene p-n junctions. We show how the transport problem in the presence of magnetic field can be solved with the help of a Lorentz transformation, and use it to investigate magnetotransport in p-n junctions. Finally, we review recent proposal to use Fabry-Pérot resonances in p-n-p structures as a vehicle to investigate Klein scattering, another hallmark phenomenon of relativistic dynamics.
Dispersion in a relativistic degenerate electron gas
Journal of Plasma Physics, 2007
Relativistic effects on dispersion in a degenerate electron gas are discussed by comparing known response functions derived relativistically (by Jancovici) and nonrelativistically (by Lindhard). The main distinguishing feature is one-photon pair creation, which leads to logarithmic singularities in the response functions. Dispersion curves for longitudinal waves have a similar tongue-like appearance in the relativistic and nonrelativistic case, with the main relativistic effects being on the Fermi speed and the cutoff frequency. For transverse waves the nonrelativistic treatment has a nonphysical feature near the cutoff frequency for large Fermi momenta, and this is attributed to an incorrect treatment of the electron spin. We find (with two important provisos) that one-photon pair creation is allowed in superdense plasmas, implying relatively strong coupling between transverse waves and pair creation.
Relativistic Quantum Response of a Strongly Magnetised Plasma. II. Ultrarelativistic Pair Plasma
Australian Journal of Physics, 1992
Approximate analytic expressions are derived for the linear response 4-tensor of a strongly magnestised, mildly relativistic electron plasma. The results are obtained within the framework of quantum plasma dynamics, thus the response contains relativistic and quantum effects that are essential in a super-strong magnetic field. The response is obtained in terms of relativistic plasma dispersion functions known as Shkarofsky functions. These functions allow the wave properties of the plasma to be studied without resorting to complicated numerical schemes. The response derived is valid for radiation with frequency up to about the cyclotron frequency and is of use in the theory of spectra formation in X-ray pulsars. In addition, a simple graphical technique is introduced that allows one to visually locate the roots of the resonant denominator occurring in the response, as well as determine the conditions under which both roots are valid and contribute to absorption.
Propagation of Ordinary and Extraordinary Modes in Ultra-Relativistic Maxwellian Electron Plasma
Progress of Theoretical Physics, 2010
Modes of ultra relativistic electron plasma embedded in a strong magnetic field are investigated for perpendicular propagation. Using Boltzmann-Vlasov equation, a general expression for the conductivity tensor is derived. An ultra-relativistic Maxwellian distribution function is employed to derive different modes for strong magnetic field limit. In particular, the dispersion relations for the ordinary mode and the extra ordinary mode (O-mode and X-mode) are obtained. Graphs of these dispersion relations and the imaginary parts of the frequency are drawn for some specific values of the parameters. It is observed that the damping rate increases gradually, reaches some maximum point and then decreases for larger wavenumbers. Further, increasing the strength of the magnetic field lowers the maximum value of the damping rate.
Dispersion Properties of Co-Existing Low Frequency Modes in Quantum Plasmas
Acoustic Waves, 2010
Contrary to classical plasmas, the number density of degenerate electrons, positrons/holes in quantum plasmas is extremely high and they obey Fermi-Dirac statistics whereas the temperature is very low. Plasma and quantum mechanical effects co-exist in such systems and many unusual effects like tunneling of electrons, quantum destabilization, pressure ionization, Bose-Einstein condensation and crystallization etc. may be equally important (Bonitz et al., 2009). Their properties in equilibrium and nonequilibrium are governed by many-body effects (collective and correlation effects) which require quantum statistical theories and versatile computational techniques. The average inter-particle distance n-1/3 (where n is the particle density) is comparable with electron thermal de Broglie wavelength