Effect of a large‐amplitude circularly polarized wave on linear beam‐plasma electromagnetic instabilities

Abstract

[1] In a previous paper, sufficiently large-amplitude and left-handed ''pump waves'' propagating parallel to the background magnetic field were shown to stabilize a moderately dense beam in a proton plasma against the generation of waves drawing their energy from the differential streaming motion of the beam [Gomberoff, 2003]. We now examine the general case of both left-hand and right-hand pump waves and their effects on beam instability as a function of pump wave amplitude and frequency, beam speed, and plasma component temperatures. We find that the left-hand pump wave always gives beam stability above a threshold amplitude. Larger threshold trend with increasing beam speed and lower ones with increasing temperature. It is also shown that they can stabilize left-hand polarized instabilities in the case of large drift velocities. The right-hand pump similarly suppresses beam instabilities when its pump frequency is below the linearly unstable range of frequencies. However, when its pump frequency is within the range of instability, that part of the range below the pump frequency is stabilized beyond a threshold amplitude, but the part above becomes even more unstable in the presence of a right-hand pump.

Linear and nonlinear electromagnetic and electrostatic instabilities in a plasma with two ion beams

“…Nonlinear ion‐acoustic like instabilities can occur in a system with one and two ion beams [ Gomberoff et al , 2003, 2004a, 2004b, 2005; Hoyos and Gomberoff , 2005; Gomberoff and Hoyos , 2005; Gomberoff , 2006a, 2006b, 2006c, 2007a]. In the presence of two ion beams, nonlinear ion‐acoustic like waves can be triggered by linear ion‐acoustic waves associated supported by the background plasma and by each one of the beams [ Gomberoff , 2007b].…”

“…The presence of large amplitude waves in the solar wind has been invoked in order to account for some unresolved problems [ Gurnett et al , 1979; Kurth et al , 1979; Gurnett , 1991; Gomberoff et al , 2003; Araneda and Gomberoff , 2004; Kaghashvili et al , 2003, 2004; Gomberoff et al , 2005]. The fact that the stabilization properties of the magnetosonic instability in the presence of two beams can be different than that of the case of only one beam, can also help to understand such processes.…”

“…It has been shown that in the presence of only one ion‐beam, finite amplitude circularly polarized waves can stabilize linear magnetosonic waves when there is only one linear magnetosonic instability region [ Gomberoff , 2003; Araneda and Gomberoff , 2004]. When there are two linear magnetosonic instability regions, the linear instability growth rate and instability range are increased by the presence of the nonlinear wave [ Gomberoff et al , 2003, 2004a]. In the presence of 2 beams a similar situation was encountered.…”

“…It has also shown that the finite amplitude waves can destabilize linearly stable ion‐acoustic waves [ Gomberoff et al , 2003, 2004a, 2004b]. In the presence of 2 beams ion‐acoustic waves associated to the background plasma, and those associated to the beams, can separately become unstable, namely, each pair of forward and backward propagation ion‐acoustic waves can become nonlinearly unstable [ Gomberoff , 2007b].…”

Nonlinear dissipation of circularly polarized Alfvén waves due to the beam-induced obliquely propagating waves

“…Gomberoff 20,21 first carried out the linear analysis of ion beam instabilities in the presence of the finite amplitude circularly polarized Alfv en waves and demonstrated that the growth of the beam instabilities are stabilized. Later, the stabilization processes were numerically confirmed by numerical simulation by using onedimensional (1-D) hybrid code.…”