2019, no. 3

### PREDICTION OF NONLINEAR EFFECT FOR ANISOTROPY OF CHARGED PARTICLE PITCH ANGLE DISTRIBUTION AT GEOSTATIONARY ORBIT

#### Smolin S.V.

The new phenomenological model of a dynamics prediction of perpendicular anisotropy index of charged particle pitch angle distribution at geostationary (geosynchronous) orbit (GEO) in the Earth’s magnetosphere, and also in any circular orbit depending on local time $$LT$$ in an orbit and the geomagnetic activity index $$K_p$$ is offered. Comparison of model at a qualitative physical level with the numerous experimental data received from 1999 to 2007 is lead. It is proved, that the general analytical dependence of perpendicular anisotropy index of charged particle pitch angle distribution on GEO received as a first approximation can be used (especially for conditions of magnetically quiet time) for quantitative forecasts and comparisons with experimental data on GEO after attraction of corresponding effective cross-sections for charge exchange and Coulomb collisions for electrons, protons and ions. It is received for the offered mathematical model, that half of width of the general analytical dependence on local time $$LT$$ in an orbit $$\delta_{LT} = 6$$ h $$LT$$ (when $$K_p \approx const$$, for example, within one day) is constant and not dependent on the $$K_p$$-index. The nonlinear effect is theoretically predicted for a difference between the maximal value of perpendicular anisotropy index of charged particle pitch angle distribution (in local midday $$LT$$ = 12 h) and the minimal value of perpendicular anisotropy index (in local midnight $$LT$$ = 0 h) on GEO from $$K_p$$-index of geomagnetic activity. The nonlinear effect for anisotropy of charged particle pitch angle distribution will be, possibly, to some extent and on other radial distances from the Earth.

Keywords: the Earth’s magnetosphere, geostationary orbit, modeling of anisotropy, prediction of nonlinear effect, new model.

UDC: 533.951, 550.385

PACS: 52.65.-y, 94.30.-d

DOI: 10.17238/issn2226-8812.2019.3.88-97