THEMIS MISSION PRESHIP REVIEW Search Coil Magnetometer Michael

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 • 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. • FM 1 Preamp was replaced with the FM 6 (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 F 1 probe Thermal Vacuum testing it was noted that the Y axis was saturated at a lower level than expected (-3. 5 V instead of -5 V). 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 FM 6 preamp shows that no other unit has this problem. MPSR SCM- 5 UCB, Oct 26, 2006

Preamp Exchange • • Only preamp was exchanged, FM 1 sensor remains on probe. Difference between preamps is less than 0. 1 d. B. FM 6 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 – F 5 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 FM 1. Preamp swapped for FM 6. Discussed above. CLOSED. All previous SCM PFRs closed. MPSR SCM- 7 UCB, Oct 26, 2006