This chapter contains sections titled: Introduction Simulation of the Ion Storm Time Distribution The Numerical Simulation Results Conclusion

We examine one well‐observed event on November 3, 1997, when clear signatures of intense nose structures were observed during substorm activity on three subsequent inner magnetosphere crossings by Polar and Interball Auroral probe. Tracing particles numerically in stationary electric (Volland‐Stern) and magnetic (T96) field models shows that the inward displacement of the intense nose structure in this case could not be formed only by convection in a time‐stationary electric field. We add time varying electric and magnetic fields to the tracing procedure which propagate toward the Earth and represent the dipolarization process at a substorm onset. These results show that particles could be moved into the inner magnetosphere within some tens of minutes, consistent with the observations.

A class of events when plasma sheet particles penetrate to the ring current region termed 'intense nose' structures observed on Polar/CAMMICE ion spectrograms is examined. A well-observed event occurred on November 3, 1997, when clear signatures of an intense nose structure were observed during substorm activity on three subsequent inner magnetosphere crossings by Polar and Interball Auroral probe. We trace particles numerically in stationary (Volland-Stern and Tsyganenko T96) and time-varying (Gaussian electric field pulse and corresponding magnetic field) fields to examine the inward motion of the nose structure. In our tracing procedure particles are lost due to convection outflow to the dayside magnetopause and charge exchange with neutral hydrogen. We also take into account the energy loss by particles due to the ionization. We inject several particle clouds with time delays of about one minute during the particle tracing. For the case of November 3, 1997 event the modeling predicts that under time varying fields particles could be moved into the inner magnetosphere within a few tens of minutes, which is consistent with the observations. We use the tracing procedure to model the observed particle fluxes in the intense nose structures and discuss the energy evolution of particles during the motion in both stationary and time-dependent fields.

This paper presents results of observational and modeling work on the dynamics in the inner magnetosphere during geomagnetic storms. Using statistics from POLAR/CAMMICE/MICS instrument it is shown that the ring current energy density is a complex function of the solar wind input and substorm activity. These results are examined using time-varying models for the magnetic and electric fields during storm periods. It is shown that (even strong) stationary convection electric field does not produce a sufficiently high-energy ring current. The same is true for a single electric field pulse representing an isolated substorm. Our preliminary results indicate that a series of substorms with inward transport and acceleration of particles by inductive electric fields are required for the production of an intense ring current.

Trapped particles of the radiation belts provide a considerable part of plasma pressure at low L-shells. The evaluations of this part during quiet times can be made on the basis of existing trapped radiation models. The radial profiles of plasma pressure at 1.2 < L < 7 were obtained by using the empirical AP8MAX model of trapped radiation (L < 6.6) and the theoretical model of the distribution of the proton fluxes in the Earth's radiation belts (L < 7) developed on the basis of the numerical solution of the radial diffusion equation with dissipation processes. The calculations were compared with AMPTE/CCE data. The contribution of quiet-time plasma pressure profile producing the quiet-time ring current to Dst-variation was obtained about 15 nT which is comparative with the magnetic field disturbances during weak and moderate magnetic storms (Dst = −40 ≈ −100 nT).

In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR particles and SEPs) to the SEU rate is discussed with an allowance for the shielding thickness.

Fluxes of energetic electrons and MeV protons at altitudes of about 500 km were studied in the experiment onboard "CORONAS-I" satellite, launched in March 1994. We present results of analysis of different charged particle distributions: mixture of protons E-p > 30 MeV and electrons E-e > 2 MeV, electrons with E-e = 0.5-1.5 MeV and protons with E-p = 1-4.5 MeV. We found anomal high fluxes of charged particles under the Earth's radiation belts (RB) near some L < 2.5, which were not taken into account in RB models earlier. Quasi-trapped electron peaks at L approximate to 2.1, narrow electron peaks at L approximate to 1.6 and a significant electron peak at L approximate to 1.3 in the western side of Brazilian Magnetic Anomaly were observed. Besides, proton fluxes mainly near the geomagnetic equator at different longitudes were detected. Fluxes of quasi-trapped electrons with energies > 1.3 MeV at L approximate to 1.6 and L approximate to 1.3 were absent. Dependencies of anomalous electron and proton flux value on L, and local time for Northern and Southern hemispheres were investigated. (C) 1999 Elsevier Science Ltd. All rights reserved.

One of the main parameters, which control the generation of currents and electric fields in the magnetospheric trap, is the plasma pressure. At present the complete picture of the plasma pressure distribution in the magnetospheric trap has not been obtained yet. Trapped particles of the radiation belts provide a considerable part of plasma pressure at low L-shells. The evaluations of this part during quiet times can be made on the basis of existing trapped radiation models. The radial profiles of plasma pressure at 1.2 < L < 7 were obtained using the trapped radiation model AP8 MAX (L < 6.6) and the theoretical model of the distribution of the proton fluxes in the Earth's radiation belts (L < 7) developed on the basis of the numerical solution of the radial diffusion equation with dissipation processes. The calculations were compared with AMPTE/CCE data. It was shown that they are in good agreement at low L-shells. The magnetic field produced by such pressure profiles is analyzed. During the magnetospheric disturbances only the outer part of this pressure distribution is changed. The observed magnetic field disturbance is a result of the difference between the disturbed and quiet-time plasma pressure profiles. The role of geomagnetically effective eastward ring current existing near the inner edge of the plasma sheet is analyzed. (C) 1999 Elsevier Science Ltd. All rights reserved.

A new method of numerical simulation of the proton pitch angle distribution (PAD) based on Liouville's theorem is presented. It yields good results for that region of the Earth's magnetosphere where the transport rate far exceeds the loss processes (charge exchange and Coulomb collisions) rate. Obtained numerical models of the proton PAD are in good agreement with the experimental data and explain all features of the PAD of proton fluxes with energy E > 50 keV experimentally measured in the Earth's magnetosphere at 3 < R/RE < 7.5 (RE is Earth's radius) and different MLT (magnetic local time) during geomagnetically quiet periods.

Radial evolution of the proton pitch angle distributions at L<5.25 for 0.03<E<10.0 MeV is considered for various models of the radial diffusion (with various correlation between coefficients of the magnetic and electric diffusion and various dependencies of these coefficients on geomagnetic latitude) and selected spacial distributions of the neutral exosphere atoms and cold plasma of the plamasphcre. The results of the numerical simulation are compared with experimental data. It is shown that the best agreement of numerical models with experimental data is achieved using for the numerical simulation radial diffusion coefficients that are independent of geomagnetic latitude, given by D-E = 5 x 10(-6) L(10) / (L(4) + mu(2)) and D-M = 5 x 10(-9) L(10) R(E)(2)day(-1).