eberhard pulz karl-heinz jäckel, oliver bronkalla
TRANSCRIPT
Eberhard PulzKarl-Heinz Jäckel, Oliver Bronkalla
1. Introduction
2. Serson’s Method
3. Cs-He-Magnetometer
4. Measuring Method
5. Coil System and Switching Technique
6. Theoretical Estimations and Limits
7. Design of Coil System
8. Installation of the Instrument
9. Results
10. Conclusion
1. Introduction
2. Serson’s Method
3. Cs-He-Magnetometer
4. Measuring Method
5. Coil System and Switching Technique
6. Theoretical Estimations and Limits
7. Design of Coil System
8. Installation of the Instrument
9. Results
10. Conclusion
Serson‘s Method
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4
FFFA
A
FFST
TSF
ATSF
ATSF
A - additional field strengthFo - magnetic field strength without an additional fieldF+/- magnetic field strength with an additional fieldS – auxiliary quantityT – magnetic field strength at desired direction
F 0
T - A
A
T
F_
S
F+
Cs-He-Magnetometer
Cs - Lamp
Cs- Sensor
Cs-He- Sensor
He Conversations Formula
0236888.28
frequencyF
Measuring Sequence for Each Second
180 msec
0 200 400 600 800 1000 timemsecfrequency counter in current switching
operation 180 msec
C+ E- F C- E+
True North
Bias field
Top view
Measurement Arrangement
Magnetometer Electronics
Switching Unit
Current source
Frequency Counter
GPS10MHz
Clock
LINUXComputer
SensorCoils
Estimation of Errors
Additional field strength for a given magnetometer noise about 0,005nT rmsand a desired noise in the components of 0,01nT rms
additional field strength of about 5000nT
Effect of tilting of the vertical axis of the bias coilfor ±1’tilting, we got for X= ±13nT
Effect of tilting the azimuth angle between the additional Field and the magnetic meridian
for ±1’tilting, we got for Y= ±5,5nT ΔX= ±3E-03
.g
North South
MirrorLaser
PSD (20x20mm2)(Position Sensitive Diode)
Top viewTop view
E
a
mE
2tan
9
g = 1’ is about 5mm at PSD
a
Coil system
s=2.1•10-2
s=8•10-3
s=1.9•10-2
Conclusions
Cs-He magnetometer absolute accuracy 0.1 nTsum of noise at NGK < 5 pT rms @ 180 msec
Orthogonal coil system: suspended, turnable, LASER controlled
Realtime (GPS) LINUX-controlled system
Result: 1 sec mean values for all components
Reducing the number of manually absolute measurements to some / year
Thank you for your attention