1. Solar wind in the outer heliosphere: IPS observations at the decameter wavelengths. N.N. Kalinichenko, I.S. Falkovich, A.A. Konovalenko, M.R. Olyak, I.N. Bubnov Institute of Radio Astronomy, Kharkiv, Ukraine

2. The solar wind blows a giant bubble with size of about 100 AU called the heliosphere.

3. The interplanetary scintillations (IPS) technique

4. Decameter range allows us to observe the interplanetary scintillations at large elongations OR to probe rarefied plasma in the outer heliosphere weakly scattering the high frequencies.

5. Our investigations of the solar wind in the outer heliosphere briefly consist of: Theoretical investigations and modelling. Theoretical investigations and modelling. Observations. Observations. Fitting the theoretical model to the observed IPS characteristics Fitting the theoretical model to the observed IPS characteristics

6. Models of the solar wind One flow model with parameters:,, is the distance from the sun Slow-speed stream with parameters and one or two high-speed stream (s) with parameters, = 1АЕ where, is the stream thickness Multi-flow model including:

7. Spectrum analysis. Spectrum analysis. Dispersion analysis. Dispersion analysis. Methods Scattering of decameter radio waves by the rarefied plasma of the outer heliosphere is well described by methods based on the multiple scattering theory such as Feynman’s path-integral technique.

8. ,,,,,, Spectrum analysis where is the spatial spectrum of electron density fluctuations; is the dispersionof the relative electron density fluctuations are flow thickness, the outer and inner turbulence scales., ; ; The spectrum of the intensity fluctuations in one point. For multi-flow model

9. Dispersion analysis The cross-correlation between scintillations in two points The cross-spectrum The dispersion dependence whereis the interferometer base r

10. Observations Radio telescope UTR-2Radio telescope URAN-2 Radio telescopes operate at the frequencies from 9 to 32 MHz.

11. The scintillation spectra (a) and dispersion curves (b) for radio source 3C196 a b The example of the model fitting

12. The reconstructedstructure of the solar wind The reconstructed structure of the solar wind

13. The annual statistics of the velocities of slow(solid line) and fast (dashed line) solar wind streams in the outer heliosphere. The annual statistics of the velocities of slow(solid line) and fast (dashed line) solar wind streams in the outer heliosphere.

14. The annual statistics of the spectral indices of the electron density fluctuations of slow (solid line) and fast (dashed line) solar wind streams.

15. Tracking of high-speed solar wind streams in the outer heliosphere The solar wind parameters obtained by Genesis Discovery Mission The solar wind parameters obtained by IPS observations

16. Harmful effects Ionospheric effects. Ionospheric effects. Radio interference. Radio interference. Angular broadening due to interstellar scattering. Angular broadening due to interstellar scattering. Records of scintillations at decameter wavelengths contain evidences both the interplanetary medium impact and Earth’s ionosphere effects.

17. LOFAR’s frequency range, from 10 to 250 MHz, will provide an excellent possibility to observe the interplanetary scintillations at all radio source elongations, in other words, to probe the interplanetary plasma in the inner and outer heliosphere, simultaneously. LOFAR’s frequency range, from 10 to 250 MHz, will provide an excellent possibility to observe the interplanetary scintillations at all radio source elongations, in other words, to probe the interplanetary plasma in the inner and outer heliosphere, simultaneously. As for the outer heliosphere, perhaps, the use of the frequencies from 30 to 50-60 MHz allows us to minimize the harmful effects of the ionosphere and radio interference and to increase the number of the compact radio sources that are suitable for IPS observations with the preservation of the method sensitivity. As for the outer heliosphere, perhaps, the use of the frequencies from 30 to 50-60 MHz allows us to minimize the harmful effects of the ionosphere and radio interference and to increase the number of the compact radio sources that are suitable for IPS observations with the preservation of the method sensitivity.