Download - C. Störmer, 1904; 1929; 1950
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C. Störmer, 1904; 1929; 1950
Allowed and forbidden regions for charged particles coming from infinity (e.g. SEP & CR)
in vicinity of magnetic dipole
Lemaître and Vallarta, 1932
Lemaire,J. , Effects of a southward magnetic field on Störmer’s allowed regions, Adv. Space Research, 31, N° 5, 1131, 2003
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Lemaire et al., Journal Atmospheric Solar Terrestrial Physics, 67, 719, 2005
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Magnetic field : IGRFBz = 0
Oxygen ion• 10 MeV • ppa 20°• L= 2
Periodicities• Gyro : 0.056 s• Bounce : 4.8 s• Drift : 154 s
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Magnetic field: dipoleBz = 0 & EF = 0
Oxygen ion• 10 MeV • ppa 20°• L= 2 Periodicities• Gyro : 0.054 s• Bounce : 4.9 s• Drift : 154 s
• Bounce phase beating: 102 s (after 23 bounces)
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Magnetic field: Dipole+ variable Bz: (alike geomagnetic storm): • Dst: -100 nT• No waves
Oxygen ion • 10 MeV; • ppa 20°• L = 2 Periodicities: • Gyro: 0.054 s• Bounce: 4.9 s• Drift : 157 s
• Bounce phase beatingafter 23 bounces
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Magnetic field: Dipole+ variable Bz: (alike geomagnetic storm): • Dst: -100 nT• No waves
Oxygen ion • 1 MeV; • ppa 20°• L = 2 Periodicities: • Gyro: 0.12s• Bounce: 13 s• Drift : 1570 s
Drift velocity is 10 times smaller thus the number of mp is reduced by the same factor
Smaller dispersion of Bm ; GyroRadius smaller by factor 3.3 Equatorial gyroperiod of 0+ is 16 times smaller than that of protons; therefore they are more prompt to violate the second Alfvén condition for adiabatic motion / first order guiding center approximation.
Note however again the strict adiabatic recovery of kinetic energy
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SUMMARY OF SIMULATION RESULTS
•Betatron acceleration/deceleration remains the major mechanism for particle mirroring close to equatorial plane
• Fermi-like deceleration/acceleration is also an essential mechanism during magnetic storms
• ULF waves (Pi2) are certainly also good candidates to accelerate particles to higher energies
• For all these mechanisms kinetic energy and adiabatic invariants change in a reversible way, provided Alfvén conditions are verified
• The energy of trapped particles is not conserved when elmg waves are in resonance with their gyro period at any place during its bounce motion, or during its drift motion.
• it has not yet been convincingly demonstrated that these resonant wp-interactions alonoe can accelerate all the particles simultaneously up to MeV energies,in a time as short as observed (recovery phase).
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PROSPECTIVE
During main phases of magnetic storms, mirror point of all charged particles of any energy and pitch angle are lifted up to higher altitudes (1);
their rates of collisions with ionospheric and atmospheric constituents are then reduced (2);
their kinetic energy is then also reduced (3); their rate of precipitation into the atmosphere are reduced (4);
they accumulate closer to equatorial region (5); this storage is enhanced by non-resonant pitch-angle scattering, and w-p interactions with all kinds of elmg waves of a wide range of frequencies and phases (6).
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PROSPECTIVE ( DURING RECOVERY PHASES)
During recovery phases the altitudes of mirror points decrease for particles of all energies and all pseudo pitch angles; particles are re-energetized (7);
flux of trapped particles at lower altitudes is then enhanced (8);
precipitation into atmospheric is enhanced due to the widening of the loss cone angle, and non-resonant pitch angle scattering with VLF waves, EMIC waves and others …(8)
Simple explanations are simpler to understand