INTERBALL

ASPI Consortium

Measurements of fields and waves onboard the Interball tail probe

PI's of instruments belonging to the INTERBALL-ASPI Wave-Consortium:

E.Amata, J.Blecki, J.Büchner, J.Juchniewicz, S. Klimov, S.Romanov, J.Rustenbach.

Participating Institutions:

Department of Automatic Control and Systems Engineering, Sheffield University, Sheffield, UK Institute of Metrology, St.Peterburg, Russia Institute of Physics of Atmosphere, Academy of Sciences of Czech Republic, Praha, Czechia Interplanetary Space Physics Institute, CNR, Frascati, Italy Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau, Germany Max-Planck-Institut fuer extraterrestrische Physik, Aussenstelle Berlin, Germany Space Research Center, Polish Academy of Sciences, Warsaw, Poland Laboratory of Physics and Chemistry of the Environment, CNRS, Orleans, France Sussex Space Centre, Falmer, UK Space Science Department, ESA, Noordwijk, The Netherlands Special Design Division, Ukrainian Academy of Sciences, Lviv, Ukraine Space Research Institute, Russian Academy of Sciences, Moscow, Russia

Importance of wave and field measurements in space plasmas

Over the years of space research magnetic and electric fields as well as plasma waves were shown to play a significant role in various space plasma processes. At the bow shock wave they provide the necessary dissipation and the observed particle acceleration, at the magnetopause they allow the transfer of energy from the solar wind into the magnetosphere, they seem to provide the dissipation in reconnection regions etc. Also, plasma waves are a very sensitive indicator of a lack of thermal equilibrium in space plasmas. Features of the particle distribution function which may be of a small amplitude, localized in phase space or have a short lifetime, can produce strong plasma waves. One example is the, produced by electron beams at the bow shock of the Earth. These beams are rarely identified in the particle data. The temporal resolution of plasma wave measurements is about the inverse of the frequency of the wave - i.e. usually much higher than particle sensors allow. Suitable wave and field receivers as well as onboard data processing systems allow time resolutions of a few milliseconds. This is an orders of magnitude higher resolution as compared to typical plasma and particle instruments, which is an important step forward in studying boundaries and other small scale structures. As an example we show the magnetic field variation of the INTERBALL-1 bow shock crossing August 22, 1995.

To provide high sensitivity of the electric field, magnetic field and plasma currents measurements a special program of magnetic, electric cleanliness and electromagnetic compatibility measures was implemented basing on the experience of the previous experiments. Unique configuration of the spacecraft with the spin axis pointing to the Sun ensures identical shadowing of electric field sensors. The location of the ASPI sensors on INTERBALL-1 is shown below.

Location of the ASPI sensors on INTERBALL-1

The first three months of the Interball-tail operation in orbit were used by the ASPI teams mainly for estimates of stability of measured parameters and effective sensitivity. The following characteristics of the operating ASPI sensors were obtained.

Characteristics of the operating ASPI sensors

Instrument / sensor	Parameter	Frequency range	Measurement range / discretization
Magnetic field measurements
MIF-M/BPP	DC vector	0-2 Hz	300/0.29 nT
MIF-M/BPP	AC vector	2-25 Hz	30/0.005 nT
MIF-M/BPP	AC 1 component	1-40000 Hz	0.0004 nT at 100 Hz(*)
FGM-I/DM1-3	DC vector	0-35 Hz	128/1 nT
Electric field measurements
OPERA/BD1-6	DC vector	0-3 Hz	115/0.9 mV/m (Ey)
OPERA/BD1-6	DC vector	0-3 Hz	570/5 mV/m (Ex,Ez)
OPERA/BD1-6	AC vector	0.1-25 Hz	115/0.9 mV/m
Plasma current measurements
FGM-I/DM1-3	AC 1 component	0.1-40000 Hz	10^-15 A/cm2/sqrt(Hz)(*)
BD-7/C2-X	AC 2 component	0.1-40000 Hz	10^-15 A/cm2/sqrt(Hz)(*)

(*) - sensitivity

Some first results

ASPI measurements at the magnetopause outbound crossing, August 26, 1995.

Magnetic field colour spectrogram (MIF-M) in the 0.5-32 Hz frequency range (bottom panel) displays strong ULF/ELF turbulence in the magnetosheath (right side) with the intensity and frequency span enlargement. Electric field colour spectrogram (OPERA) in 0.5-32 Hz band (top panel) shows: (a) wave bursts at the magnetopause and in the magnetosheath (b) electrostatic ELF emission inside magnetosphere (left side). Colour bar at the bottom panel right side shows the color coding of logarithmic wave amplitude.

Measurements by three-axial fluxgate magnetometers in the MIF-M and FGM-I instruments of ASPI combined with ones from two fluxgates of FM-3I provide a unique possibility to estimate and monitor DC magnetic interferences of the spacecraft.

Reference

Klimov,S., S.Romanov, E.Amata, J.Blecki, J.Büchner, J.Juchniewicz, J.Rustenbach, P.Triska, L.J.C.Woolliscroft, S. Savin, Yu. Afanas'ev, U.de Angelis, U.Auster, G.Bellucci, F.Farnik, V.Formisano, P.Gough, R.Grard, V. Korepanov, H.Lehmann, B.Nikutowski, M.Nozdrachev, S.Orsini, M.Parrot, A.Petrukovich, J.L.Rauch, A.Skalsky, J.Slominski, J.G.Trotignon, J.Vojta and R.Wronowski, ASPI experiment: Measurements of fields and waves onboard the INTERBALL-TAIL mission, in INTERBALL - Mission and Payload , CNES-IKI-RSA, p.120-152, 1995.

J. Buechner
10-12-2001