Energetic electron motion in the geomagnetic field Energetic electron motion in the geomagnetic field Energetic electron motion in the geomagnetic field Energetic electron motion in the geomagnetic field - - - - Test particle simulation and observations Test particle simulation and observations - Test particle simulation and observations Test particle simulation and observations - - - Laboratory, Space, and Astrophysical Plasma Workshop Laboratory, Space, and Astrophysical Plasma Workshop Laboratory, Space, and Astrophysical Plasma Workshop Laboratory, Space, and Astrophysical Plasma Workshop Feb. 22, 2009 Feb. 22, 2009 Feb. 22, 2009 Feb. 22, 2009 APL Jaejin Lee Jaejin Lee Jaejin Lee Jaejin Lee (Korea Astronomy and Space science Institute) (Korea Astronomy and Space science Institute) (Korea Astronomy and Space science Institute) (Korea Astronomy and Space science Institute)
In My Talk, In My Talk, In My Talk, In My Talk, � How energetic electrons are accelerated How energetic electrons are accelerated How energetic electrons are accelerated How energetic electrons are accelerated � How they are lost (precipitation) from the radiation belt How they are lost (precipitation) from the radiation belt How they are lost (precipitation) from the radiation belt How they are lost (precipitation) from the radiation belt � How they interact with waves How they interact with waves How they interact with waves How they interact with waves
Radiation Belt Radiation Belt Radiation Belt Radiation Belt • Discovery of Van Allen radiation belts – Explorer 1, 1958 • Trapped protons & electrons, spatial distribution (2-7 R E ), energy (~MeV) ������������������������������������� ������������
Three Adiabatic Invariant Three Adiabatic Invariant Three Adiabatic Invariant Three Adiabatic Invariant � �� � ⊥ � � = First Adiabatic Invariant � � ∫ = � � �� Second Adiabatic Invariant � Third Adiabatic Invariant Total magnetic flux Φ enclosed by a drift surface
Charged Particle Motion in Magnetosphere Gyro, bounce and drift motions Gyro ~millisecond, bounce ~ 0.1-1 second, drift ~1-10 minutes To change particle energy, must violate one or more invariants Sudden changes of field configurations Small but periodic variation of field configurations
It It’ ’s still open problem. s still open problem. It It ’ ’ s still open problem. s still open problem. Proposed physical processes Acceleration Acceleration: large- and small-scale recirculations, heating by Acceleration Acceleration Whistler waves, radial diffusion by ULF waves, cusp source, substorm injection, sudden impulse of solar wind pressure and etc. Loss Loss Loss Loss: pitch angle diffusion, Coulomb collision, and Magnetopause shadowing. Transport Transport Transport Transport � � � �� � � = × + � � � � � � ��
Solving Ordinary Derivative Equation Solving Ordinary Derivative Equation Solving Ordinary Derivative Equation Solving Ordinary Derivative Equation = � �� � � � � � � � � � � = + = + + � � �� � � � � � � �� � � � � � � � + � � � � � � � � � � � = + + � � � � � � � � + � � � � Euler method Euler method Euler method Euler method Runge- Runge Runge Runge - -Kutta method - Kutta method Kutta method Kutta method
Loss Process Loss Process Loss Process Loss Process Pitch Angle Diffusion by Field Line Curvature Pitch Angle Diffusion by Field Line Curvature Pitch Angle Diffusion by Field Line Curvature Pitch Angle Diffusion by Field Line Curvature
Relativistic Electron Dropouts (RED) Relativistic Electron Dropouts (RED) Relativistic Electron Dropouts (RED) Relativistic Electron Dropouts (RED) LANL data
Electron Dropout Sequence Electron Dropout Sequence Electron Dropout Sequence Electron Dropout Sequence
Space Space Space Space Environment Environment Environment Environment Date (Jun 2004) Date (Jun 2004) Date (Jun 2004) Date (Jun 2004)
Relativistic electron dropout Relativistic electron dropout Relativistic electron dropout Relativistic electron dropout characteristics characteristics characteristics characteristics 1. Fast dropouts for 1 ~ 5 hours 1. Fast dropouts for 1 ~ 5 hours 1. Fast dropouts for 1 ~ 5 hours 1. Fast dropouts for 1 ~ 5 hours 2. Observed for both of electrons and protons 2. Observed for both of electrons and protons 2. Observed for both of electrons and protons 2. Observed for both of electrons and protons 3. More effective for higher energy charged particles 3. More effective for higher energy charged particles 3. More effective for higher energy charged particles 3. More effective for higher energy charged particles 4. Started from dusk and midnight sector and 4. Started from dusk and midnight sector and 4. Started from dusk and midnight sector and 4. Started from dusk and midnight sector and propagate to noon sector propagate to noon sector propagate to noon sector propagate to noon sector 5. Correlation with magnetic field stretching 5. Correlation with magnetic field stretching 5. Correlation with magnetic field stretching 5. Correlation with magnetic field stretching
Electron Loss Electron Loss Electron Loss Electron Loss Escape from the magnetopause Escape from the magnetopause Escape from the magnetopause Escape from the magnetopause - Magnetopause can be compressed inside L = 6.6 - De-trapping of particles and drift outward to magnetopause Loss to the atmosphere Loss to the atmosphere Loss to the atmosphere Loss to the atmosphere - Pitch angle scattering into the loss cone - Observation of particle precipitation
First Adiabatic Invariant Violation First Adiabatic Invariant Violation First Adiabatic Invariant Violation First Adiabatic Invariant Violation κ = ρ � � � � � � � � = � ������ �� ��������� � ρ = ���� ������
First Adiabatic Invariant Violation First Adiabatic Invariant Violation First Adiabatic Invariant Violation First Adiabatic Invariant Violation First adiabatic invariant : The magnetic moment of gyrating particle is First adiabatic invariant : The magnetic moment of gyrating part First adiabatic invariant : The magnetic moment of gyrating part First adiabatic invariant : The magnetic moment of gyrating part icle is icle is icle is conserved conserved as long as magnetic field is constant during a gyro period. conserved conserved as long as magnetic field is constant during a gyro period. as long as magnetic field is constant during a gyro period. as long as magnetic field is constant during a gyro period. Pitch angle diffusion by field line curvature Pitch angle diffusion by field line curvature Pitch angle diffusion by field line curvature Pitch angle diffusion by field line curvature
Loss cone filling (Particle simulation) Loss cone filling (Particle simulation) Loss cone filling (Particle simulation) Loss cone filling (Particle simulation) Electrons of 0.0075% are lost by precipitation. dF/dt = (-2 x 0.000075) F / T_b E-folding loss time : ~ 3.1 hr
Precipitations by curvature explains a lot of things of RED Precipitations by curvature explains a lot of things of RED Precipitations by curvature explains a lot of things of RED Precipitations by curvature explains a lot of things of RED event event event event � � Fast loss process for 1 ~ 5 hours � � Fast loss process for 1 ~ 5 hours Fast loss process for 1 ~ 5 hours Fast loss process for 1 ~ 5 hours � � Observed for both of electrons and protons � � Observed for both of electrons and protons Observed for both of electrons and protons Observed for both of electrons and protons � More effective for higher energy charged particles � � � More effective for higher energy charged particles More effective for higher energy charged particles More effective for higher energy charged particles � � Correlation with magnetic field stretching � � Correlation with magnetic field stretching Correlation with magnetic field stretching Correlation with magnetic field stretching � Started from dusk and midnight sector and propagate to noon sect � � � Started from dusk and midnight sector and propagate to noon sect Started from dusk and midnight sector and propagate to noon sector Started from dusk and midnight sector and propagate to noon sect or or or
Electron Energy Dispersion Electron Energy Dispersion Electron Energy Dispersion Electron Energy Dispersion STSAT STSAT STSAT STSAT- - - -1 Data observed on Jun 14, 2004 1 Data observed on Jun 14, 2004 1 Data observed on Jun 14, 2004 1 Data observed on Jun 14, 2004
Can the Tsyganenko model reproduce the energy dispersion? Jun 14, 2004 Data -Dst index : -20 nT -Solar wind pressure : 2.81 nPa -IMF By : 7.25 nT -IMF Bz : -7.1 nT Real Input Parameters -Dst index : -33 nT -Solar wind pressure : 2.81 nPa -IMF By : 7.25 nT -IMF Bz : -9.1 nT
Electron Orbits on the XY Plan Electron Orbits on the XY Plan Electron Orbits on the XY Plan Electron Orbits on the XY Plan
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