SURA-WIND experiments: intensity fluctuations due to Faraday effect

Yu. Tokarev, Yu. Belov, G. Boiko, G. Komrakov

Radiophysical Research Institute, N.Novgorod, Russia

Authors are grateful to J.-L. Bougeret (LESIA, Meudon, France) and M.Kaiser (NASA/GSFC, Greenbelt, USA) for fruitful collaboration

SURA radar facility

Vasil’sursk, Russia (56.07 N, 46 E)

Operating frequency 4.3 – 9.5 MHz

Antenna array sizes 300 m x 300 m

Zenith angle range –45o - +45o

Circular polarization modes (O or X)

Three transmitter submodules

Effective power radiation 17–160 MW

WIND spacecraft

RAD2 WAVES receiver

Operating frequency range 1.075 –13.835 MHz

Two orthogonal dipole antennas X(11m) and Y(15m)

Spinning vehicle (3 sec per turn)

Sensitivity 7 nV/ Hz0.5 Freq. width 20 kHz Sampling rate 63 ms

Sunward WIND orbits

Ecliptic plane localization

Revolving axis is pointed to South ecliptic pole

Apogee 80 – 250 Re

Perigee 10 – 15 Re

Development of high frequency pecularity during the s/c moving away the Earth magnetosphere

effsws RVf

skmswV /400

Eeff RR )40...15(m33 Hzfs )3...1(

WIND trajectory Fluctuation spectra of received SURA signals

Example of spectrum decomposition to ionospheric and IPS components

Example of time record with pronounced Faraday effect

Total intensity Itot and Iz / Itot ratio

December 27, 1999

Example of session with regular Iz / Itot variations

November 23, 1999

Example of session with quasi-regular Iz / Itot variations

Aug 18-19, 1999

Iz and Itot fluctuation spectra of Faraday fringes Aug 18-19, 1999

Iz dynamic spectrum of Faraday fluctuations Aug 18-19, 1999

Degree of linear polarization and total intensity Aug 18-19,1999

Degree of linear polarization and total intensity November 23, 1999

Basic equations

cos)()()(103

)(2

1

317

221

cmLcmNGHRM

RMLnnc

e

 

100,5.0,35

103 kmLGHcmeN

Ionosphere:

6

1006.1,5

103,3

1.0 kmLGHcmeN

Magnetotail:

=33 m

Faraday rotation angle

Rotation measure

tt sin2

105.4

Hzht 51071/15 HzA |sin|103 2

Characteristic frequencyof Faraday fluctuations:

14

10

Degree of linear polarization of SURA radiation:

),()cos1/(sin 22 AconstZZPlin Z– zenith angle, A – azimuth of line of sight

cos105.4 2

CONCLUSIONS

• A method to study the polarization state of radio signals of ground-based transmitters using RAD2 WAVES observations for SEP-mode is proposed.

 • It was found that degree of linear polarization of SURA

emission out the earth ionosphere is close to expected value only for angular range near center of the radar beam.

 • Obtained results could be used for calibration of space radio

instrumentation particularly of the STEREO radio receivers at first stage of the mission.

References

C.G.M.van't Klooster, Yu.Belov, Yu.Tokarev, J.L.Bougeret, B.Manning, M.Kaiser. Experimental 9 MHz Transmission from Vasil'sursk in Russia to the WIND Spacecraft of NASA. Preparing for the FUTURE. 1995. V.5. N.4. P.1-3.

Yu.V.Tokarev, M.Kaiser , Yu.I.Belov, G.N Boiko, N.V.Muravieva. Small-scale turbulence of solar wind around the near-Earth bow shock. Astronomicheskii Vestnik. 2000. V.34. N.2. Pp.1-4 (in Russian).

N. A. Barkhatov, N. S. Belliustin, J.-L. Bougeret, S. Yu. Sakharov and Yu.V. Tokarev. Influence of solar wind magnetic field on small-scale near-earth turbulence. Izvestya VUZov, Radiophysica. 2001. V.44. N 12. Pp.993-1002 (in Russian).

N.Muravieva and Yu.V.Tokarev. Decametric sounding of near Earth plasma:correlation and fractal analysis of scintillation data. Astrophysics and Space Science. 2001. V.277. P.331-334.

Yu.V.Tokarev. Turbulence of geo-disturbed region of solar wind (SURA-WIND experiments). Proc. of FSU Conference “Actual problems of solar physics and star activity”. N.Novgorod, June 2-7, 207, 2003. V I. Pp. 191-196 (in Russian).