Transcript thm_MPSR_11_SCM - themis - University of California, Berkeley

THEMIS MISSION
PRE-SHIP REVIEW
Search Coil Magnetometer
Michael Ludlam for Alain Roux
University of California - Berkeley
MPSR
SCM- 1
UCB, Oct 26, 2006
Overview
Overview
•
Instrument Status
•
Problem Failure Reports
MPSR
SCM- 2
UCB, Oct 26, 2006
Instrument Status
•
All SCM instruments are fully functional.
•
There are no outstanding issues or problems for
the SCM.
•
SCM survived probe environmental tests and are
ready for launch.
•
FM1 Preamp was replaced with the FM6 (spare
unit) after environmental testing due to a
manufacturing error (i.e. not related to the probe
environmental tests).
MPSR
SCM- 3
UCB, Oct 26, 2006
Preamp Exchange
During F1 probe Thermal Vacuum testing it was noted
that the Y axis was saturated at a lower level than
expected (-3.5V instead of -5V).
Problem was traced to the preamp Y
axis cube.
Part was returned to the manufacturer in
France where analysis showed that a
wrong resistor was installed in the circuit
that controls the supply current of the
output op-amp.
Problem was not spotted until probe
thermal vacuum as this was the first time
the sensor was attached to the preamp
and fully saturated.
MPSR
SCM- 4
UCB, Oct 26, 2006
Preamp Exchange
•
Testing of preamp with saturated sensor was not part of
standard preamp check out.
•
All of the other testing of the preamp was done either with a
nulling feedback plug or with the sensor in a Mumetal can to
reduce the external magnetic field so the preamp is not
saturated.
•
One other time when the preamp was connected to a
unshielded sensor was during Instrument Suite thermal
vacuum. During this time the Y axis was not fully saturated
and therefore the problem was very difficult to spot.
•
Data from other preamps during probe thermal vacuum and
testing of FM6 preamp shows that no other unit has this
problem.
MPSR
SCM- 5
UCB, Oct 26, 2006
Preamp Exchange
•
•
Only preamp was exchanged, FM1 sensor remains on probe.
Difference between preamps is less than 0.1dB.
FM6 preamp testing prior to installation
• Thermal vacuumed for 10 cycles (2
thermal cycles already done by SCM
prior to shipment)
• Vibrated to workmanship levels.
• DC Magnetics
• Pre and post functional test including
saturation of preamp to show full dynamic
range.
• Transfer function of preamp measured
after tests.
Preamp installed on probe and tested –
functioning correctly
MPSR
SCM- 6
UCB, Oct 26, 2006
Problem Failure Reports
3 PFR on SCM since last review
PRF 208 – F5 SCM sensor connected during deperming of
probe.
Levels induced in preamp not high enough to harm instrument.
CLOSED.
PFR 217 – Cal level of SCM during thermal vacuum lower than
expected.
When the sensor is saturated the cal signal produces a non
standard response. CLOSED.
PFR 227 – Problem with Y axis on FM1.
Preamp swapped for FM6. Discussed above. CLOSED.
All previous SCM PFRs closed.
MPSR
SCM- 7
UCB, Oct 26, 2006