THEMIS Instrument CDR 1 UCB, April 19-20, 2004 EFI Preamp Sensor G.T. Delory, A. Hull, D. Schickele, J. Bonnell & The EFI Team University of California - Berkeley

THEMIS Instrument CDR 2 UCB, April 19-20, 2004 Overview Evolution of the CLUSTER-II Design

THEMIS Instrument CDR 3 UCB, April 19-20, 2004 Requirements & Specs Measurement Performance Electric Fields DC kHz DC: Coupling impedances up to 10,000 M . AC: Input Capacitance = 8 pF Radial C coupling ~13 pF, Axial C coupling ~6.5 pF Environmental Requirements  C operating temp; survive 12 cycles to  132 C. ~750 kRAD/year behind 1 mm of Al

THEMIS Instrument CDR 4 UCB, April 19-20, 2004 Electrical Performance

THEMIS Instrument CDR 5 UCB, April 19-20, 2004 Block Diagram Spin-Plane Boom (SPB) Unit Sub Axial Boom (AXB) Unit 3m thin wire, d ~10 mil sphere, d ~8 cm Preamp Housing, d ~2.3 cm 3m Preamp Housing, d ~2.3 cm 1 m

THEMIS Instrument CDR 6 UCB, April 19-20, 2004 Electrical Diagram

THEMIS Instrument CDR 7 UCB, April 19-20, 2004 Layout Engineering Model Layout

THEMIS Instrument CDR 8 UCB, April 19-20, 2004 Mechanical & Thermal OP15 (TO-99 pkg) Mechanical Tantalum rad shield Socket Spring contact Connector shell Usher (positive bias) Guard (negative bias) PCBPin Spacecraft Wire/sphere

THEMIS Instrument CDR 9 UCB, April 19-20, 2004 Layout – Cont’d

THEMIS Instrument CDR 10 UCB, April 19-20, 2004 Mass, Power, & Thermal Mass 40 g each unit (can be lowered by using Al instead of brass for top piece) Power <70 mW per Preamp (allocated 85 mW) Thermal Must survive  132 C for ~12 cycles (3 hr eclipse) Nominal operating T of Dag-coated surface ~50 C

THEMIS Instrument CDR 11 UCB, April 19-20, 2004 Parts Op-Amp OP-15AJ MIL-STD 883, CRRES Heritage Meets radiation requirement Requires further thermal screening (hermetic integrity, pin- pull test, die-bond inspection) Passive Components Meet all requirements except thermal Thermal screening will occur using subset of tests for OP-15

THEMIS Instrument CDR 12 UCB, April 19-20, 2004 Schedule April –Vibration tests –Cable/connector/EM assembly May –Thermal tests to  132 C –Integration of preamp EM with BEB EM, full end-to-end EFI system test June –Additional parts screening (outside facility) –Destructive testing/inspection of fully assembled unit at lowest thermal predict July –Implement any design modes necessary for qualification issues –Final layout, loading, and electrical testing –System level testing: Preamp/Boom/BEB signal chain

THEMIS Instrument CDR 13 UCB, April 19-20, 2004 Schedule – Cont’d Aug –Begin flight unit fabrication Sep –1 st Flight Unit Delivery

THEMIS Instrument CDR 14 UCB, April 19-20, 2004 Issues THERMAL Plan: Qualify preamp as complete unit in parallel with individual parts qualification program Develop several alternative strategies to mitigate potential issues/failures at  132 C –Ceramic board –Hybrid construction Consider addition of temperature sensor to 1 SPB and 1 AXB sensor/spacecraft Similar systems regularly undergo temperature swings down to ~  100 C (i.e., CLUSTER II). We will verify this for the THEMIS design