Abstract
An important property associated with turbulence in plasmas and fluids is anomalous transport. Plasma, being a good conductor, can in addition be affected by turbulence causing an anomalous resistivity that can significantly exceed its classical counterpart. While turbulent transport may be adequately described in configuration space, some aspects of the anomalous resistivity are best accounted for in phase space. Kinetic phenomena like electron and ion phase space vortices can thus act as obstacles for the free flow of slow charged particles. Plasma instabilities and large amplitude plasma waves are candidates for contributions to the anomalous resistivity by generating such structures. Langmuir waves can be relevant, but also others, such as upper- as well as lower-hybrid waves in magnetized plasmas. Often these anomalous resistivity effects can be small, but due to the large spatial and temporal scales involved in space plasmas, planetary ionosphere and magnetosphere in particular, even such moderate effects can be important. This mini-review is discussing elements of the description of plasma turbulence with particular attention to wave phenomena that contribute to anomalous resistivity and diffusion. Turbulence effects can have relevance for space weather phenomena as well, where ground based and airborne activities relying on for instance Global Positioning and Global Navigation Satellite Systems are influenced by plasma conditions in geospace.
Highlights
Plasmas, magnetized plasmas in particular, can support a variety of wave phenomena, electromagnetic as well as electrostatic
There are solid evidences that fully developed strong resistive electrostatic driftwave turbulence in plasmas confined by strong magnetic fields develops a ∼ k−5 power-law spectral subrange for fluctuations in the electrostatic potential (Tchen et al, 1980; Pécseli, 2015; Pécseli, 2016)
Simple physical arguments (Alber, 1978; Pécseli, 2014) give that a wave-decay or a modulational instability involving wavelengths longer than the correlation length associated with the spectrum are stable (Alber, 1978; Pécseli, 2014), details will differ for decay and modulational instabilities
Summary
Plasmas, magnetized plasmas in particular, can support a variety of wave phenomena, electromagnetic as well as electrostatic. In neutral fluids and gases, ‘strongly’ turbulent states often develop, while in plasmas, turbulence is often observed to be ‘weak’ For discussing this distinction, we consider a nonlinear model wave equation (Dupree, 1969; Similon and Sudan, 1990; Galtier, 2009) in the form. Any quadratically nonlinear partial differential equation with a first order time derivative can be brought in the form of Eq 1 by a Fourier series representation of the variables in configuration space One such example is the Navier-Stokes equation (Kollmann, 2019) where Ql represents the incompressible fluid velocity component ul, and iω(k) → k2], where ] is the fluid kinematic viscosity. The linear dispersion relation can be identified in the (ω, k)-space, demonstrating the importance of the ω(k) term in Eq 1, while for strongly turbulent conditions a similar analysis shows enhanced amplitudes for a wide range of wave vectors with no discernible frequency-wavenumber relation. If the simulations reproduce the observed data, it can be assumed that the numerical results can be trusted for information not directly accessible for confirmation by measurements
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
