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THEMIS PROBE FM2 PRE-ENVIRONMENTAL REVIEW DC MAGNETICS TESTING Michael Ludlam Magnetics Lead

THEMIS PROBE FM2 PRE-ENVIRONMENTAL REVIEW DC MAGNETICS TESTING Michael Ludlam Magnetics Lead University of California - Berkeley. Introduction. Component Magnetics Is the probe ready for the DC Magnetics test? Facilities Are the facilities ready for the DC Magnetics test?

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THEMIS PROBE FM2 PRE-ENVIRONMENTAL REVIEW DC MAGNETICS TESTING Michael Ludlam Magnetics Lead

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  1. THEMIS PROBE • FM2 PRE-ENVIRONMENTAL REVIEW • DC MAGNETICS TESTING • Michael Ludlam • Magnetics Lead • University of California - Berkeley

  2. Introduction • Component Magnetics • Is the probe ready for the DC Magnetics test? • Facilities • Are the facilities ready for the DC Magnetics test? • Requirements • Do we know what the requirements are? • Test Procedure • Do we have a reviewed procedure ready?

  3. Component Magnetics Testing • Status of FM2 Probe components: • All Instruments including IDPU have been magnetically mapped. Some bus components have been mapped – BAU, AEB, Battery (QM). • One problem found with BEB board in IDPU found to have magnetic transistors. All BEB boards have been degaussed separately and verified to be non-magnetic. • BAU and AEB boxes found to be slightly more magnetic than expected – due to relays. • Baseplate with RCS piping and valves have not been degaussed – a known magnetic offender with latch valves. • Overall, units are either in or close to magnetics budget.

  4. Facilities • Coil structure has been strengthened and tested for probe. • Night time stability measurements have been taken to verify stability of environment. • UCB provided MGSE for holding probe has checked by JPL for fit and magnetics.

  5. Requirements Requirements from Magnetics Contamination Control Plan (THM-SYS-002D) derived from the Mission Requirements Document (THM-SYS-001). • 5nT spacecraft field at location of FGM (M31a). • Stability of spacecraft field shall be less than 0.1nT over 12 hours at the location of the FGM (M31b).

  6. Test Procedure • Test Procedure written by Pablo Narvaez (JPL) incorporating UC Berkeley DC Magnetics test procedure originally written for the purpose. • THEMIS Probe DC Magnetics Test Procedure (JPL D-33980). • Procedure is ready.

  7. Test Flow Night 1 5nT requirement As received survey Repeated after probe vibration Deperm Spacecraft Post deperm survey 5nT requirement Expose spacecraft to Earth’s field & survey 0.1nT stability requirement

  8. Test Flow Night 2 Power up probe 5nT requirement Powered probe survey 0.1nT stability requirement

  9. Magnetic Survey Vertical Mapping Setup Horizontal Mapping Setup Location of magnetometers: 1.5m from cg (for Analysis) and 2m from edge (FGM location)

  10. Deperming Deperming done using slowly varing DC field whilst probe is rotated in the x-y plane. The deperm is repeated in the x-z plane. The maximum field for the deperm will be 15 Gauss. If this does not achieve good results, it is possible to increase this to 20 Gauss.

  11. Perm Field Test Using the Earth’s field as a perm field the probe will be exposed to more than maximum field it will see in space. Comparing the field measured with the probe and without the probe in a given location will show the distortion of the field caused by the probe. This will give the stability we are likely to see from perming over an orbit.

  12. Powered Test The probe will be powered using the fully charged battery and a magnetics survey test run again to see what field is induced by the probe from the currents flowing in the spacecraft.

  13. Test Personnel Pablo Narvaez – JPL Bob Snare – UCLA Ellen Taylor – UCB Michael Ludlam – UCB (by phone)

  14. Summary • Component Magnetics • Units mapped at UCB generally look magnetically clean. • Facilities • JPL DC magnetics coil facility is ready. • Requirements • 5nT spacecraft field at location of FGM. • 0.1nT stability over 12 hours at location of FGM. • Test Procedure • THEMIS Probe DC Magnetics Test Procedure (JPL D-33980) is ready.

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