Algorithm for forecasting of radiating influence on microsatellite equipments

Аuthors

Biruykov V. I.^*, Biryukovа M. V.^**

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: aviatex@mail.ru
**e-mail: 610kaf@mail.ru

Abstract

For forecasting of reliable work of space vehicles (SV) devices the knowledge of radiating conditions along the flight line of Earth satellite is necessary. The exact calculation of radiation stored doses in electro-radio devices (semi-conductor microcircuit chips, diodes, triodes and other products) as a part of SV instrumental technics in condition of long-term active existence on orbit is impossible. The forecast of solar proton events for a long term and corresponding modeling of magnetic sphere indignations from various influences have not so high probability. In this case the maximum and, sometimes, the overevaluated estimations of stored doses are important for comparison of summarized doses stored by satellite equipments with radiating firmness of its element base for a long time.
Created in Moscow State University scientific research institute JAF computational models of radiating conditions are difficult for the users who do not have special space physics preparations. Programs of particles existential distribution of space various ionizing radiation are inaccessible, bulky and calculations are time-consuming. Simultaneously there is a considerable quantity of publications in Russia and abroad about physical processes and experimental measurements of particles spatial-temporal distribution of ionizing radiation. However in present time the uniform database for estimation of distributions total fluences particles and radiation doses reflecting the real radiating conditions on the surface and inside the SV instrumental technics is not developed.
The physical mechanism of radiation influence is reduced to definition of spatial distribution of the absorbed dose in design elements of SV instrument compartments taking into account their mutual shielding. Another mechanism of space radiation influence is accumulation of introduced volume charge in dielectric materials of electro and radio products which are the part of devices elements. One of a variants number of spatial distribution calculation of absorbed dose and the introduced electric charge in SV design elements is reduced to definition of an equivalent thickness of the protective aluminium screen for a concrete point of instrument space. For this purpose the rays are traced in all spatial directions from chosen point to elementary platforms into which the surface of settlement model is broke. Further the screens thickness in direction of each trace are calculated considering the mutual elements shielding by walls of various body frames and physical properties of screens materials.
Space vehicles are exposed to influence of some ionizing radiation, for example the radiations from the natural and artificial radiating belts of the Earth consisting of charged particles of various getting ability. In our case for an estimation of their influences the NASA models — АР8, АЕ 8 generated on the basis of streams averaged values of protons and electrons in a certain range of energy were used.
Estimations of other components such as high-energy galactic radiation, the electrons contribution of external magnetic sphere, the albedo-particles formed with respect to interaction between high-energy particles and atmosphere, and the account of other kinds of ionizing radiation is carried with the help of normative documents made as the state standards.
Input coordinates of NASA — АР 8 and АЕ 8 models are McIlwain parameters L, B. They consider the integrated invariant and ratio of magnetic field induction in a concrete point of space to value of the Earth magnetic field along the magnetic power line (a dipole magnetic cover). For transfer of geocentric coordinates of SV orbit into the McIlwain coordinates , both in Russia and in the USA the maps for orbits various altitudes from the Earth are calculated and constructed. The isolines of equal values of L and B coordinates with respect to height and width for fixed values of longitude are put on the maps.
Breaking satellite orbit into the parts with minor alteration of L and B coordinates and defining for them the differential spectra of electrons and protons from natural radiating belts of the Earth and also from the influence of solar space radiations the distribution of weights around the units of considered device were defined as a result.
The local absorbed doses by devices internal elements taking into account their arrangement on the satellite, units design and satellite configuration are calculated. Radiating firmness of devices elements was defined, doze stock factors were calculated and conclusions about working capacity of devices units in relation to doze effects were made.

Keywords:

ionizing radiation, ЕRPZ, SКL, protons, electrons, ⍺-particles, dozes

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