Differential ion streaming in the solar wind as an equilibrium state

[1] We analyze the nonlinear evolution of differential streaming between core protons and alpha particles (or any secondary minor protons) based on the analysis of fully nonlinear multifluid MHD equations. It is shown that such an ion beam-plasma system possesses an equilibrium state with a remnant of differential streaming. The properties of this state are studied. The system through the action of nonlinear hydromagnetic waves can attain an equilibrium state which is characterized by a “gyrating” motion of both ion populations with a phase shift of π. The waves which bring about a such transition are either the Alfven or magnetosonic modes, depending upon the beam speed. It is shown that the equilibrium differential speed between the alphas and protons Vαp lies between 0.8 and 1.5 VA but only in a certain regime of injection speeds of the alphas. A similar picture obtains for proton/proton configurations in which the number density of the secondary protons imposes a constraint on the injection speeds, 1.5 ≥ Vp,p/VA ≥ 0.3 (VA is a local Alfven speed). Nonlinear Alfven waves bring about a transition to equilibrium states with much higher differential velocities uαp(upp), proportional to the injection speeds, than magnetosonic waves.

[1]  L. Ofman,et al.  Multiple ions resonant heating and acceleration by Alfvén/cyclotron fluctuations in the corona and the solar wind , 2004 .

[2]  S. Livi,et al.  Observational evidence for marginal stability of solar wind ion beams , 1987 .

[3]  W. Feldman,et al.  Ulysses observations of differential alpha-proton streaming in the solar wind , 1996 .

[4]  William Daughton,et al.  Electromagnetic proton/proton instabilities in the solar wind , 1998 .

[5]  Yu Lin,et al.  Generation of nonlinear Alfvén and magnetosonic waves by beam–plasma interaction , 2003 .

[6]  Alfvén waves, alpha particles, and pickup ions in the solar wind , 1995 .

[7]  H. Rosenbauer,et al.  Solar Wind Helium Ions: Observations of the Helios Solar Probes Between 0.3 and 1 AU E. MARSCH, 1 K.-H. MOHLHXUSER, 2 H. ROSENBAUER, 1 , 1982 .

[8]  M. Neugebauer.  Observations of solar-wind helium , 1981 .

[9]  J. Steinberg,et al.  Differential flow between solar wind protons and alpha particles: First WIND observations , 1996 .

[10]  W. Feldman,et al.  Ulysses near‐ecliptic observations of differential flow between protons and alphas in the solar wind , 1994 .

[11]  W. Feldman,et al.  Helium and hydrogen velocity differences in the solar wind , 1976 .

[12]  J. Steinberg,et al.  Helium energetics in the high‐latitude solar wind: Ulysses observations , 2001 .

[13]  J. Hollweg,et al.  Deceleration of streaming alpha particles interacting with waves and imbedded rotational discontinuities , 2003 .

[14]  J. F. Mckenzie,et al.  Nonlinear stationary whistler waves and whistler solitons (oscillitons). Exact solutions , 2003, Journal of Plasma Physics.

[15]  J. F. Mckenzie,et al.  Nonlinear stationary waves and solitons in ion beam-plasma configuration , 2004 .

[16]  P. Hellinger,et al.  Hybrid simulations of the expanding solar wind: Temperatures and drift velocities , 2003 .

[17]  E. Dubinin,et al.  Oscillitons and gyrating ions in a beam‐plasma system , 2003 .

[18]  L. Gomberoff,et al.  Stabilization of right‐hand polarized beam plasma instabilities due to a large‐amplitude left‐hand polarized wave: A simulation study , 2004 .

[19]  L. Yin,et al.  Electromagnetic alpha/proton instabilities in the solar wind , 2000 .

[20]  J. F. Mckenzie,et al.  Resonant wave acceleration of minor ions in the solar wind , 1982 .

[21]  L. Gomberoff,et al.  Effect of a large-amplitude circularly polarized wave on linear beam-plasma electromagnetic instabilities , 2003 .

[22]  J. F. Mckenzie.  Interaction between Alfvén waves and a multicomponent plasma with differential ion streaming , 1994 .

[23]  L. Gomberoff,et al.  Stabilization of linear ion beam right-hand polarized instabilities by nonlinear Alfvén/ion-cyclotron waves , 2003 .

[24]  S. Gary,et al.  Observed constraint on proton‐proton relative velocities in the solar wind , 2000 .

[25]  E. Marsch,et al.  Dependence of the proton beam drift velocity on the proton core plasma beta in the solar wind , 2004 .

[26]  J. F. Mckenzie,et al.  HEATING AND ACCELERATION OF MINOR IONS IN THE SOLAR WIND , 1998 .

[27]  S. Peter Gary,et al.  Theory of Space Plasma Microinstabilities , 1993 .

[28]  L. Yin,et al.  Consequences of proton and alpha anisotropies in the solar wind: Hybrid simulations , 2002 .

[29]  S. Habbal,et al.  Proton/alpha magnetosonic instability in the fast solar wind , 2000 .

[30]  J. F. Mckenzie,et al.  The acceleration of minor ion species in the solar wind , 1979 .

[31]  A. Viñas,et al.  Proton core temperature effects on the relative drift and anisotropy evolution of the ion beam instability in the fast solar wind , 2002 .

[32]  L. Ofman.  Three-fluid model of the heating and acceleration of the fast solar wind , 2004 .

[33]  S. Gary,et al.  Electromagnetic proton/proton instabilities in the solar wind: Simulations , 1999 .