1. Mutual Impedance MEasurements, MIME as part of the EJSM JGO/RPWI
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Laboratoire de Physique et Chimie de l'Environnement et de l’Espace
3A, avenue de la Recherche Scientifique
F Orléans cedex 02, France
Mutual Impedance MEasurements, MIME
as part of the EJSM JGO/RPWI
Jean Gabriel TROTIGNON and Jean Louis Rauch
LPC2E, CNRS, Université d’Orléans, Orléans, France
EJSM JGO/RPWI Team Meeting, Nov. 2009
Phone: (33 2) ; Fax: (33 2) ;

2. Presentation Outline Experiment Objectives Principle of Measurements
EJSM JGO/RPWI Team Meeting, Nov. 2009
Mutual Impedance MEasurements, MIME as part of the EJSM JGO/RPWI
Presentation Outline
Experiment Objectives
Principle of Measurements
Range of Measurements
Heritage
Instrument
Conclusion
Téléphone: (33 2) Secrétariat: (33 2)
Télécopie (Fax): (33 2)

3. JGO/RPWI/MIME Experiment Objectives (1 / 2)
Provide reliable/accurate measurements of total plasma density & thermal electron temperature, in Jupiter system environment (solar wind included);
Contribute to the study of the interactions between solar wind & Jupiter’s Magnetosphere, in particular around Ganymède and Callisto;
Give insight into thermal coupling between neutral & charged particles;
Detect plasma boundaries and identify plasma regimes;

4. JGO/RPWI/MIME Experiment Objectives (2 / 2)
Enable self and/or mutual impedances of LP-PWI and possibly RA-PWI electric antennae to be determined as a function of plasma environment;
Determine the effective length of these antennae (then allow E-field component of waves to be calibrated);
Possibly measure the physical/deployed length of antennae;
Contribute to onboard calibrations of LP-PWI, and maybe SCM and RA-PWI (calibration signal can be delivered)
 cross-calibration between sensors.

5. MIME Principle of Measurements
A sinusoidal signal of known amplitude & frequency, coming from a current (or voltage) generator, is applied to antenna probe or wire shield, by short pulses (some ms), while induced voltage (or current) is simultaneously measured.
Antenna impedance Z = V / I is a function of frequency & plasma conditions.
Transmitted frequency varies step by step in a frequency bandwidth that includes the plasma frequency expected at Jupiter’s Magnetosphere (Ne proportional to Fpe2).
Impedance spectra are computed onboard by FFT/DFT algorithms.
Plasma parameters, such as density and electron temperature, are derived from variations of both impedance modulus and phase close to Fpe.

6. MIME Principle of Measurements (cont’d)
Thermal electron temperature Te shall be determined provided
2 λD < L < a few tens λD ,
where L is the tip-to-tip antenna length and the plasma λD Debye Length
For the total electron density Ne, L must be higher than λD and can be higher
than a few tens λD depending on the onboard FFT frequency resolution
Ne can be determined from resonance and/or wave signatures at the plasma frequency Fpe, the upper-hybrid frequency Fuh and Berstein mode frequencies Fqn
As a bonus, the magnetic field strength B can be derived from the electron cyclotron frequency Fce and its gyroharmonics nFce
Ne (cm-3) = Fpe2 (kHz) / 81
Fce (Hz) = 28 B (nT)
Fuh = (Fpe + Fce)1/2
Fpe (kHz) = 6687 Te1/2 (eV) / λD (cm)

7. Fuh FQ2 FQ3 FQ4 Fpe = 468 kHz = 1.17 Fce  Ne = 2,700 cm-3
4 March 2005, 22:12:39.14 UT, 0 dB ≡ 0.6 μV Hz1/2
616 kHz
Fuh
896
FQ2
1232
FQ3
1624
FQ4
406 kHz
Fce
266 kHz
Interference
812
2Fce
1176
3Fce
1568
4Fce
2,090 km altitude
Fpe = 468 kHz = 1.17 Fce  Ne = 2,700 cm-3

8. MIME Range of Measurements
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Laboratoire de Physique et Chimie de l'Environnement et de l’Espace
3A, avenue de la Recherche Scientifique
F Orléans cedex 02, France
MIME Range of Measurements
Phone: (33 2) ; Fax: (33 2) ;

9. Ne and Te should be measured provided 0.5 cm ≤ λD ≤ 3 m (or 1 m)
Fpe (kHz) Ne
cm-3
10-3 eV
λD (cm)
0.01 eV
0.1 eV
1 eV
10 eV
100 eV
0.285
0.001
740
0.705
0.006
300
949
3 103
3 104 1
0.012
210
670
2.1
0.05
100
320
103
104
2.23
0.06
950
6.7
0.55
316 7
0.6
955 10
1.23 21 67
5.4
318 22 6
960 55 70 60
123.5
540
220
1 000
0.2
0.67
3 500 2 19
9 000
106
0.02
0.07
0.23
0.74
2.35
7.4
Comparison between a 2 x 3 m long antenna (green) and a 2 x 1 m one (yellow);
Ne and Te should be measured provided cm ≤ λD ≤ 3 m (or 1 m)

10. Callisto (Gurnett et al., 2000)
Ne ~ 400 cm-3 (180 kHz) at 535 km
> 100 cm-3 (90 kHz) at km
Iomospheric peak: – cm-3
(750 – 1200 kHz)
at km
Ganymede (Gurnett et al., 1996;
Eviatar et al., 2001)
Ne ~ 200 – 300 cm-3 (130 – 160 kHz)
at km
Ne peak cm-3
(180 – 450 kHz)

11.  Expected MIME Range of Measurements
Frequency bandwidth: from a few hundred Hz* up to 3 MHz;
Debye length: from 0.5 cm up to 1-3 m (depending on antenna length);
Total plasma density: 0.01 – cm-3;
Electron temperature: 0.01 – 100 eV.
The E-field antenna is assumed to be of the order of 2 to 6 m tip-to-tip long
(the longer, the better)
* Lower-frequency signals can be produced
for sensor calibrations (TBD)

12. Mutual Impedance Technique Heritage
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Laboratoire de Physique et Chimie de l'Environnement et de l’Espace
3A, avenue de la Recherche Scientifique
F Orléans cedex 02, France
Mutual Impedance Technique Heritage
The mutual/self impedance measurement technique has successfully been used, during nearly three decades, onboard ionospheric rockets and spacecraft (GEOS, VIKING, MARS 96, ROSETTA, and more recently BepiColombo/MMO).
Phone: (33 2) ; Fax: (33 2) ;

13. Mutual Impedance Technique Heritage (cont’d)
Active: Impedance Modulus
Passive: Natural waves
Active: Impedance Phase
ROSETTA/RPC/MIP Observations in the Earth’s Plasmasphere

14. Numerical Simulations for BepiColombo/MMO
Mutual Impedance Technique Heritage (cont’d)
Numerical Simulations for BepiColombo/MMO
Both the capacitance and the resistance of the MEFISTO antenna exhibit a peak at the plasma frequency (=> density) and a “plateau” below (=> temperature).
Here, Debye length is 5 m, which is a typical value in solar wind close to Mercury (~30 m antenna tip-to-tip length).
Double probe
Double wire-shield
Double probe
Double
wire-shield

16. CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Laboratoire de Physique et Chimie de l'Environnement et de l’Espace
3A, avenue de la Recherche Scientifique
F Orléans cedex 02, France
MIME Instrument
Phone: (33 2) ; Fax: (33 2) ;

17. Global view of MIME instrument
electric
antenna(e)
digital signal
generator
signal acquisition
ADSP
signal analyser
(FFT, phase…)
signal
controller
command word
clock
()
() also to SCM for calibrations (TBD)

18. Possible Electrical Interface: here AM²P-E to MEFISTO on BepiColombo/MMO
Output signals of synthesizer are referenced to ground

19. Electrical Interfaces : MIME to E-Field Antenna(e)
Detail of possible interface with E-Field antenna(e) for wire and mutual modes
synthesizer
MIME
output
switch
Safety relay
MIME
Sensor
Electronics
E-Field
Sensor

20. MIME may be composed of the following elements:
RPWI/MIME Elements
MIME may be composed of the following elements:
The electronic board hosted in RA (it would allow MIME to be connected to every electric/magnetic sensors);
Current probes hosted by E-field antenna deployment boxes (as in BepiColombo/MEFISTO ones);
EGSE including data processing software.

21. send calibration signal
MIME possible working modes
3 cases
current injected on LP/PWI spheres,
voltage is measured
voltage injected on boom external shield,
current/voltage is measured
send calibration signal
to a selected sensor: LP/PWI or SCM
V1 and V2 (2 channels)
V1 - V2 (1 channel)
I1 and I2 (2 channels)
I1 - I2 (1 channel)
I1 - I2 and V1 - V2 (2 channels)
“I " measured by MIME current probe
“V " measured by LP/PWI

22. MIME Measurement Point Definition
A MIME measurement point contains 3 pieces of information:
Reference spectrum (no transmission)
Power spectrum
Phase spectrum
from which Ne, Te, antenna impedances… are derived on ground.
Note: to increase SNR, each frequency may be transmitted n times depending on MIME working modes, and averages will therefore be computed onboard.

23. MIME power and mass ressources
(BepiColombo/MMO/AM2P)
Mass: 13 g each
Power consumption: 50 mW
Size: 52 mm x 52 mm
(Rosetta/MIP)
Mass: 470 g (1.3 g / cm2)
Power consumption: 1.3 W (1.6 W peak)
Size: 247 mm x 147 mm
(BepiColombo/AM2P)
Mass: 240 g (0.8 g / cm2)
Power consumption: 0.5 W (0.7 W peak)
Size: A5

24. MIME Telemetry Ressources
Survey: 1952 bits / 60 s (33 bits s-1)
Ref. spectrum (passive): 64 frequency bins x 10 bits x 1
Power spectrum: 64 frequency bins x 10 bits x 1
Phase spectrum: 64 frequency bins x 10 bits x 1
HK: 32 bits
Nominal: 6976 bits / 30 s (233 bits s-1)
Ref. spectrum: 96 frequency bins x 12 bits x 2
Power spectrum: 96 frequency bins x 12 bits x 2
Phase spectrum: 96 frequency bins x 12 bits x 2
HK: 64 bits
Burst: bits / 10 s (1 235 bits s-1)
Ref. spectrum: 128 frequency bins x 16 bits x 2
Power spectrum: 128 frequency bins x 16 bits x 2
Phase spectrum: 128 frequency bins x 16 bits x 2

25. OR E-Field Antenna Occupancy Example:
N = 24 (frequency step repetition factor; for a high signal to noise ratio)
Frequency sweep = 128 different frequency steps (FFT: 256 samples)
3 Frequency bands: 200 Hz – 20 kHz; 2 kHz – 200 kHz; 20 kHz – 2 MHz
1 or 2 acquisition channels
Acquisition time (worst case): 855 ms (including time for the plasma to be stabilized)
1 MIME channel
Ref F0 F1
F126
F127
Frequency repeated N times OR
2 MIME channels
Ref F0 F1
F126
F127
Ref F0 F1
F126
F127
MIME emission 2 times shorter
Frequency repeated N/2 times

26. Conclusion Mutual Impedance MEasurements, MIME
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Laboratoire de Physique et Chimie de l'Environnement et de l’Espace
3A, avenue de la Recherche Scientifique
F Orléans cedex 02, France
Mutual Impedance MEasurements, MIME
as part of the EJSM JGO/RPWI
J. G. Trotignon and J. L. Rauch
Conclusion
Thank you, first, for the invitation to participate in this exciting mission;
MIME may definitely contribute to the study of the Jupiter’ magnetosphere, in particular in measuring the electron plasma density and temperature, determining the effective length of electric antennae, helping out with
in-flight sensor calibrations.
Application for funding has been submitted to CNES.
Phone: (33 2) ; Fax: (33 2) ;