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Eberhard Pulz Karl-Heinz Jäckel, Oliver Bronkalla

A Quasi Absolute Optically Pumped Magnetometer for the Permanent Recording. Eberhard Pulz Karl-Heinz Jäckel, Oliver Bronkalla. Introduction Serson’s Method Cs-He-Magnetometer Measuring Method Coil System and Switching Technique Theoretical Estimations and Limits

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Eberhard Pulz Karl-Heinz Jäckel, Oliver Bronkalla

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  1. A Quasi Absolute Optically Pumped Magnetometer for the Permanent Recording Eberhard Pulz Karl-Heinz Jäckel, Oliver Bronkalla

  2. Introduction • Serson’s Method • Cs-He-Magnetometer • Measuring Method • Coil System and Switching Technique • Theoretical Estimations and Limits • Design of Coil System • Installation of the Instrument • Results • Conclusion

  3. Serson‘sMethod T - A T A F_ S F 0 F A - additional field strength Fo - magnetic field strength without an additional field F+/- magnetic field strength with an additional field S – auxiliary quantity T – magnetic field strength at desired direction +

  4. Cs-He-Magnetometer Cs-He- Sensor Cs - Lamp Cs- Sensor

  5. He ConversationsFormula

  6. Measuring Sequence for Each Second 180 msec C+ E- F C- E+ 0 200 400 600 800 1000 time msec frequencycounter in currentswitching operation 180 msec Bias field Top view True North

  7. Measurement Arrangement Magnetometer Electronics Sensor Coils GPS 10MHz Clock FrequencyCounter Switching Unit Current source LINUX Computer

  8. Estimation of Errors • Additional field strength for a given magnetometer noise about 0,005nT rms and 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 coil for ±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

  9. PSD (20x20mm2) (Position Sensitive Diode) Coil system South a North Mirror Laser . g g = 1’ is about 5mm at PSD Top view

  10. s=8•10-3 s=2.1•10-2 s=1.9•10-2

  11. Conclusions • Cs-He magnetometer absolute accuracy 0.1 nT sum 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

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