The electron-acoustic mode in a plasma with hot suprathermal and cool Maxwellian electrons

Abstract

The electron-acoustic wave, in a plasma with hot suprathermal, kappa-distributed electrons and cool, Maxwellian electrons, is investigated. This model is a generalization of those that have been investigated previously, and through its parametrization by κ, can be reduced to many previous models of the stable wave. It is found that the hot suprathermal electrons significantly increase the Landau damping of the wave at small wave numbers, i.e., in its acoustic regime. Results from a survey of parameter space, which help to identify parameters for which the stable mode will be only weakly Landau damped, are presented. The dependence of the Landau damping on the fraction of suprathermal electrons, which is related to the index, κ, of the hot electron distribution, is investigated in detail.

Electron acoustic solitons in the presence of an electron beam and superthermal electrons

“…N ob = 0, the dispersion relation (8) reduces to that of Mace et al (1999). For κ → ∞, the dispersion relation (8) is the same as obtained by Singh et al (2001).…”

Revisiting the Anomalous rf Field Penetration into a Warm Plasma

“…The wave phase velocity is ω/k = n c /n h T h /m , where n c and n h are the electron densities of cold and hot electrons, respectively, and T h is the temperature of the hot electrons. The electron acoustic waves are strongly damped by the hot electrons, unless n c n h and T c T h , where T c is the electron temperature of the cold electrons [24]. In the opposite limit, n c > 4n h , the electron acoustic waves do not exist [24].…”

“…For a Maxwellian electron distribution function, such root does not exist when ω ω p . However, the electron acoustic waves can exist if the plasma contains two groups of electrons which have very different temperatures [24]. The wave phase velocity is ω/k = n c /n h T h /m , where n c and n h are the electron densities of cold and hot electrons, respectively, and T h is the temperature of the hot electrons.…”

Electron acoustic waves in double-kappa plasmas: Application to Saturn's magnetosphere

“…Plasmas having two electron populations with different temperatures, unlike ordinary ion-electron plasmas, support propagation of the electron acoustic wave [Watanabe and Taniuti, 1977;Gary and Tokar, 1985;Gary, 1987;Mace and Hellberg, 1990]. Secondly, the fact that both the cool and hot electron components require a kappa model for their proper kinetic description implies that even previous models of the EAW, which sought to treat only the hot electrons by a kappa distribution [Mace et al, 1999], require revision if the ambient plasma conditions in the Saturnian magnetosphere are to be accurately taken into account.…”

“…[16] The parameter l a is the appropriate Debye length of species a in a kappa plasma [Chateau and Meyer-Vernet, 1991;Bryant, 1996;Mace et al, 1998Mace et al, , 1999, and reduces to l Da in the limit a → ∞.…”