Signature of Schwinger's pair creation rate via radiation generated in graphene by strong electric current

Electron - hole pairs are copuously created by an applied electric field near the Dirac point in graphene or similar 2D electronic systems. It was shown recently that for sufficiently large electric fields and ballistic times the I-V characteristics become strongly nonlinear due to Schwinger's pair creation. Since there is no energy gap the radiation from the pairs' annihilation is enhanced. The spectrum of radiation is calculated. The angular and polarization dependence of the emitted photons with respect to the graphene sheet is quite distinctive. For very large currents the recombination rate becomes so large that it leads to the second Ohmic regime due to radiation friction.Comment: 9 pages, 7 figure

Interaction of ultrarelativistic electron and proton bunches with dense plasmas

Here we discuss the possibility of employment of ultrarelativistic electron and proton bunches for generation of high plasma wakefields in dense plasmas due to the Cherenkov resonance plasma-bunch interaction. We estimate the maximum amplitude of such a wake and minimum system length at which the maximum amplitude can be generated at the given bunch parameters.Comment: 8 page

Topological spin transport of photons: "magnetic monopole" gauge field in Maxwell equations and polarization splitting of rays in periodically inhomogeneous media

Topological spin transport of electromagnetic waves (photons) in stationary smoothly inhomogeneous isotropic medium is studied. By diagonalizing photon kinetic energy in Maxwell equations we derive the non-Abelian pure gauge potential in the momentum space, which in adiabatic approximation for transverse waves takes the form of two Abelian U(1) potentials corresponding to magnetic monopole-type fields. These fields act on circularly polarized waves resulting in the topological spin transport of photons. We deduce general semiclassical (geometrical optics) ray equations that take into account a Lorentz-type force of the magnetic-monopole-like gauge field. Detailed analysis of rays in 3D medium with 2D periodic inhomogeneity is presented. It is shown that rays located initially in the inhomogeneity plane experience topological deflections or splitting that move them out from this plane. The dependence of the rays' deflection on the parameters of the medium and on the direction of propagation is studied.Comment: 16 pages, 3 figure

Whistler Wave Excitation and Effects of Self-Focusing on Ion Beam Propagation through a Background Plasma along a Solenoidal Magnetic Field

This paper extends studies of ion beam transport through a background plasma along a solenoidal magnetic field [I. Kaganovich et al., Phys. Plasmas 15, 103108 (2008)] to the important regime of moderate magnetic field strength satisfying ωce > 2βbωpe . Here, ωce and ω pe are the electron cyclotron frequency and electron plasma frequency, respectively, and βb = vb/ c is the directed ion beam velocity normalized to the speed of light. The electromagnetic field perturbations excited by the ion beam pulse in this regime are calculated analytically, and verified by comparison with the numerical simulations. The degrees of beam charge neutralization and current neutralization are estimated, and the transverse component of the Lorentz force associated with the excited electromagnetic field is calculated. It is found that the plasma response to the ion beam pulse is significantly different depending on whether the value of the solenoidal magnetic field is below or above the threshold value specified by ω cr ce = 2βbωpe, and corresponding to the resonant excitation of large-amplitude whistler waves. The use of intense whistler wave excitations for diagnostic purposes is also discussed