Abstract.Electron phase-space holes are regions of depleted electron density commonly generated during the nonlinear stage of the two-stream instability. Recently, bipolar electric field structures a signature of electron holes have been identified in the acceleration region of the auroral ionosphere. This paper compares the evolution of electron holes in 2-D and 3-D using massively-parallel PIC simulations. In 2-D, the holes decay after hundreds of plasma periods while emitting electrostatic whistler waves. In the 3-D simulations, electron holes also go unstable and generate whistlers but, due to physical processes not present in 2-D, energy flows out of the whistlers and into highly perpendicular lower hybrid modes. As a result of this difference, 3-D holes do not decay as far as 2-D holes. The differences between 2-D and 3-D evolution may have important implications for hole longevity and wave generation in the auroral ionosphere.
The radial localization of the drift Alfvén ballooning modes (DABM), proposed by Chen and Hasegawa [1991] to explain Pc 4–5 pulsations excited by highly energetic ring current protons, is examined by using WKB approximations in the radial direction. The problem is reduced to two nested one‐dimensional ones, one along the equilibrium magnetic field lines and the other in the radial direction. By ignoring kinetic effects to lowest order it is found that a localization potential well can exist for sufficiently strong earthward pressure gradient (the outer edge of the ring current). However, mode energy tunnels through a finite barrier and gets absorbed at the field line resonance layer, thereby causing damping of the global mode. This damping process imposes a minimum azimuthal mode number for the mode to be localized. The bounce‐drift resonance of highly energetic protons is treated perturbatively. The results further support the theoretical picture that antisymmetric high‐azimuthal mode‐number drift Alfvén‐ballooning modes are a good candidate instability mechanism for internally excited geomagnetic pulsations.
Effect of plasma parameters on growth and field emission of electrons from cylindrical metallic carbon nanotube surfaces Phys. Plasmas 18, 083503 (2011) Neutral-gas depletion and repletion in plasmas Phys. Plasmas 17, 043502 (2010) Energetic neutrals in the cathode sheath of argon direct-current discharges J. Appl. Phys. 106, 023305 (2009) Competitive effects of an axial magnetic field and of neutral gas depletion in a positive column Phys. Plasmas 16, 053507 (2009) Additional information on Phys. Plasmas The phase transition model for the transition from the low-confinement regime ͑L mode͒ to high-confinement regime ͑H mode͒ is extended to incorporate the effect of the neutral particles on the transition threshold. For usual edge plasma parameters, the increase of effective poloidal viscosity through charge exchange damping and reduction of the effective fluxes by both ionization and charge exchange increases the threshold power required for the transition. For plasmas with the effective energy flux smaller than the convective energy flux, the transition may be triggered by a neutral influx.
A kinetic theory of resonant interaction between electrostatic waves and the bounce motion of electrostatically trapped electrons is developed. Precise criteria are derived for the stability of electrostatic potential structures which trap electrons in a highly magnetized plasma. The theory explains the energy transfer from electron phase space holes to waves observed in simulations. It may also account for the destabilization of electrostatic waves propagating obliquely to the geomagnetic field and some characteristics of the holes as observed in the auroral ionosphere.
Abstract. A set of reduced nonlinear equations is presented, which describes the dynamics of a current layer at scale sizes below the ion skin depth. At these scales the ion motion can be ignored. These equations contain the effects of electron inertia and the Hall term with the intent of describing small-scale turbulence in the environment of the magnetopause. Magnetic shear effects are also included. It is found that the entire spectrum is linearly unstable either to the current gradient instability or to a kink-type mode. The kink-like instability, in contrast to the current gradient instability, also exists in the limit of massless electrons. The growth rate increases with decreasing current layer width and the jump of the north-south component of the magnetic field across the magnetopause.
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