Ion And Electron Kinetic Instabilities In The Solar Wind

The shaping mechanism of the velocity distribution function of the solar wind particle is a basic problem in the solar wind research.The solar wind observations always find the particle velocity distribution function being non-thermal equilib-rium state,which can include both particle beam and temperature anisotropy.When the particle velocity distribution is highly deviating from the thermal equi-librium state,the plasma waves are triggered through the wave-particle interac-tions,and these plasma kinetic instabilities dissipate the free energy of particles,which make the particle velocity distribution return back to the equilibrium state.As a consequence,the plasma kinetic instabilities play important roles in shaping the particle velocity distribution functions in the solar wind.Based on the solar wind observations and numerical solver of the plasma dispersion equation,this thesis will consider both the beam and temperature effects to comprehensively study the ion and electron kinetic instabilities.The first chapter will introduce the observed ion and electron velocity distri-bution functions in the solar wind,and this chapter will summarize the observed features of both the beam and temperature anisotropy.The second chapter will introduce the observed plasma wave modes,ion ki-netic instabilities,electron kinetic instabilities and applications of these instabili-ties in the solar wind.The third chapter presents ion kinetic instabilities resulting from both the ion temperature anisotropy and ion beam.We will show the ?pc|| and Tpc?/Tpc|| distri-butions of the electromagnetic ion cyclotron instability,the mirror instability,the fast-magnetosonic/whistler firehose instability,and the Alfven firehose instability,where ?pc|| denotes the ratio of the parallel thermal pressure of the proton core with the magnetic pressure,and Tpc? and Tpc|| denote the proton core temperatures perpendicular and parallel to the background magnetic field,respectively.Due to the ion beam,the asymmetrical distributions arise for parallel and antiparallell electromagnetic ion cyclotron instabilities and fast-magnetosonic/whistler firehose instabilities,and both the mirror instability and Alfven firehose instability pro-duce the waves with non-zero frequency.We also find a new instability driven by the ion beam,which produces left-hand polarized Alfven waves,and this instabil-ity can constrain the ion temperature in the low-?pc|| regime.Besides,we explore the electromagnetic features of these ion kinetic instabilities.The fourth chapter shows electron kinetic instabilities resulting from both the electron temperature anisotropy and electron beam.We explore the ?ec||and Tec?/Tec|| distributions of the electromagnetic electron cyclotron instability,the electron mirror instability,the periodic electron firehose instability,the ape-riodic electron firehose instability,the ordinary instability,the electron beam driven whistler instability,the electron acoustic/magneto-acoustic instability and the oblique fast-magnetosonic/whistler instability,where ?ec|| is the ratio of the parallel thermal pressure of the electron core with the magnetic pressure,and Tec? and Tec|| are the electron core temperatures perpendicular and parallel to the background magnetic field,respectively.We find that the electron beam can drive electrostatic electron acoustic waves in the low-?ec|| regime and parallel whistler waves in the medium-and high-?ec|| regimes.Due to effects of both the electron temperature anisotropy and electron beam,an oblique fast-magnetosonic/whistler instability arises in the region where?ec||?0.1-2 and Tec?/Tec||<1,and this instability has the velocity threshold Veb(?)7VA that is much lower than the threshold in the electron beam driven whistler instability.Besides,we give com-prehensive electromagnetic features in each kind of the electron kinetic instability.The fifth chapter investigates the radial distributions of the electron heat flux instability by using radial models of the magnetic field strength and plasma parameters.This chapter assumes the electron velocity distribution function con-sisting of the electron beam and electron core,and consequently the electron heat flux is mainly carried by the electron beam.Our results show that a fast electron beam mainly excites electron acoustic waves.These waves then heat electron in parallel direction through Landau resonance interactions,resulting in the parallel temperature anisotropy that would totally suppress the electron acoustic insta-bility,and only the oblique whistler heat flux instability survives.We show that electron heat flux can effectively drive lower-hybrid waves in the low-? plasma,and the excitation mechanism comes from interactions relating to the perpendic-ular electric field and beaming electrons.Moreover,our results show that the electron beam with medium drift velocity can drive the parallel whistler heat flux instability as the heliocentric distance is nearly larger than 10 times the solar radius.Finally,the sixth chapter summarizes our results,and this chapter also dis-cusses our research plan in the future.