Vortex formation in an electron plasma with a sheared flow

Abstract

The formation of vortex structures in an electron plasma with a sheared flow is investigated. The electron fluid is drifting in a self-electric field generated by an unshielded electron population. This setting is linearly unstable and an instability of diocotron (slipping-stream) type occurs. The time scale of the dynamics is assumed to be much shorter than the ion plasma and ion gyroperiods. Consequently, the ions do not respond to the wave potential and serve only as a neutralizing background. An equation determining the nonlinear evolution of the electrostatic potential in a plane perpendicular to an external magnetic field is derived within the drift approximation. The governing equation is then analyzed for the case with a localized shear in the electron fluid velocity. Possible final states of the diocotron instability are investigated analytically and solutions in the form of a tripolar vortex, a zonal flow, and a vortex street are found. The nonlinear time evolution of the diocotron instability is investigated by solving the governing equation numerically. In particular, the dynamics of nonlinearly saturated states and the formation of such states are discussed. Numerical solutions show a vortex street structure in a saturated state. The relevance of our investigation for space and laboratory plasmas is discussed.

Turbulence and transport in two-dimensional magnetized electron plasmas

“…4 The dynamics of electron plasma vortices in background vorticity distribution has been investigated both analytically and numerically 4 as well as experimentally. 7,9,10 Vortex structures have been observed [11][12][13] in low-temperature laboratory devices in which electron clouds are confined by dc electric and magnetic fields. 7 Possible stationary solutions of the latter can be cast in the form of a global vortex pattern 7,8 and a double vortex.…”

“…In a nonuniform electron magnetoplasma containing equilibrium electron density gradient and fixed ion background, the dynamics of 2D electron drift modes (EDMs) is governed by the modified NSE [7]. Possible stationary solutions of the latter can be cast in the form of a global vortex pattern [7,8] and a double vortex [7,9,10]. Vortex structures have been observed [11,12,13] in low-temperature laboratory devices in which electron clouds are confined by dc electric and magnetic fields.…”

The development and interaction of instabilities in intense relativistic electron beams

“…In this case, the intense high-energy beams of charged particles are used on relatively long distances or for long times (like in the beam traps). 8,[33][34][35][36] Different methods for mitigation or control of such instabilities are actively studied at present. 34,37,38 At the same time, the diocotron and slipping instabilities could be useful for the development of novel methods for HPM generation (see, for example, the work 23 where the effect of the microwave generation from the filamentation and vortex formation within magnetically confined electron beams was discovered and investigated).…”

Comment on “Faraday rotation in an electron-positron plasma containing a fraction of ion” [Phys. Plasmas 12, 084507 (2005)]

“…Hall and P. K. Shukla. 8 However, the difference equation ͑4͒ is not equal to zero for the hot nonequilibrium plasma with v T− v T+ 0. This fact proves the possibility of the Faraday rotation in pure e ± -plasmas and pure C 60 ± -plasma.…”

“…One more example of these symmetric plasmas is the fullerene cluster plasma ͑C 60 ± -plasma͒, which has also been produced. 5 There are many opinions that some phenomena of the ordinary electron-ion plasmas ͑the ei-plasmas͒ cannot be applied to symmetric plasmas; e.g., a sheath, 5 solitary electrostatic waves, 6 whistler modes, 7 lower hybrid modes, 7 and Faraday rotation 7,8 are absent in e ± -plasmas and C 60 ± -plasmas. J. O.…”