THEMIS Instrument PDR 1 UCB, April 19-20, 2004 Spin Plane and Axial Boom Preamps & Sensor Cable Fabrication Critical Design Review Daniel Schickele University of California - Berkeley

THEMIS Instrument PDR 2 UCB, April 19-20, 2004 Ease of disassembly to facilitate replacement of parts. Tantalum radiation shielding for OP-15 Can. Minimal difference of parts for Spin Boom and Axial boom configurations. Angled forward surfaces (Top) to reduce photoelectron flux to wire. Angled rear surface (Guard) to reduce probability of hang up upon deployment. Electrical isolation of bias surfaces. Minimum input capacitance between sensor input and preamp structure. Thermal Predicts: -120ºC to +60ºC Mechanical Requirements & Specs

THEMIS Instrument PDR 3 UCB, April 19-20, 2004 Physical Characteristics All external parts to be gold plated and DAG 213 coated. Top Screw Fitting Guard Cable Holder

THEMIS Instrument PDR 4 UCB, April 19-20, 2004 Spin Plane & Axial Boom Preamps

THEMIS Instrument PDR 5 UCB, April 19-20, 2004 Exploded SPB Preamp

THEMIS Instrument PDR 6 UCB, April 19-20, 2004 Spin Plane & Axial Boom Preamps

THEMIS Instrument PDR 7 UCB, April 19-20, 2004 PC Board Subassembly

THEMIS Instrument PDR 8 UCB, April 19-20, 2004 Preamp Discussion Outline of changes since PDR Replaced Fuzz Button with Ferrule Spring and Spring Plate Improved reliability of electrical contact to sensor Facilitated trace routing on PC Board Modified tantalum Front Shield Improved reliability of electrical contact to sensor Facilitated trace routing on PC Board Changed to Mill-Max receptacles and pins Problems swaging Keystone pins to NASA requirements

THEMIS Instrument PDR 9 UCB, April 19-20, 2004 Preamp Issues & Concerns THE SPECIFIC SITE CONCERNS ARE BASED ON OUR PRELIMINARY THERMAL ANALYSIS. A MORE EXTENSIVE THERMAL ANALYSIS IS UNDERWAY AND SHOULD BE COMPLETED IN THE NEXT TWO WEEKS. GENERAL INSPECTION NOTES All items should be inspected both pre and post test. All places where dissimilar materials are joined. All bonded surfaces visually accessible. PC BOARD ASSEMBLY Inspect Ferrule Spring for fatigue or damage. Inspect Spring Plate for deformation and it’s solder joint. All surface mount components especially their soldered joints. Pin swaged joint. OP-15 soldered leads. Front Shield contact with PC Board. PREAMPS Primary areas of concern are large diameter plastic parts: * The Bottom (which has been addressed by splitting the ring). * The Sphere Mount particularly the site of the 0-80 Flat Head Screws. * The Socket Holder fit in the guard, the Mill-Max Receptacles for loosening, and the fit of the Can Shield in the Socket Holder. Bonding between Guard, Peek Stub, and Cable Holder. AXB PREAMP SPECIFIC - Threaded joint between Sphere holder with its threaded insert and the Sensor Tip Piece. SPB PREAMP SPECIFIC - Fine Wire Crimp. Mill-Max Receptacles & Pins Flight Approval Pending. (UCB QA/GSFC QA)

THEMIS Instrument PDR 10 UCB, April 19-20, 2004 Preamp Supporting Slide 1 PC Board Assembly Data AXB Preamp Data

THEMIS Instrument PDR 11 UCB, April 19-20, 2004 Preamp Supporting Slide 2 SPB Preamp Data

THEMIS Instrument PDR 12 UCB, April 19-20, 2004 Sensor Cable Fabrication New procedure synthesized from individual heritage procedures used on FAST, Polar, and Cluster for Cable Fabrication. Designed to allow Kevlar braid to take majority of mechanical load. Designed to protect majority of fine wires in Custom cable during fabrication, test and usage in orbit.

THEMIS Instrument PDR 13 UCB, April 19-20, 2004 AXB Cable

THEMIS Instrument PDR 14 UCB, April 19-20, 2004 SPB Cable

THEMIS Instrument PDR 15 UCB, April 19-20, 2004 Cable Fabrication SPB Cable (ETU Fabrication Experience) AXB Cable Same as SPB except without Distal Braid Wire (Step 1) and bead (Step 4).

THEMIS Instrument PDR 16 UCB, April 19-20, 2004 Cable Issues & Status AXB & SPB EMU Cables ready for integration into EMU units for thermal/vacuum and vibration testing. All Gore Cable in house. EMU Cable Fixtures 90% Complete. GENERAL INSPECTION NOTES All items should be inspected both pre and post test. Of prime concern is the electrical continuity of the cables. The resistance of each lead should be measured and recorded before and after testing. Where possible Preamp functional tests should also be performed pre and post test. Examine the cable for damage where it exist the Cable Holder. Examine the area around where the cable enters the inboard Airborn connector potting brackets for signs of pull-out. AXB PREAMP SPECIFIC Inspect the Preamp for any loosening on the Stacer Tip Flange. Inspect the cable for damage from it’s rapid spooling from the Bobbin. SPB PREAMP SPECIFIC Inspect the Bead for signs of pull out or damage and verify that the Distal and Proximal Braids are electrically isolated. Examine the wire loops protruding from the Airborn connector for damage.

THEMIS Instrument PDR 17 UCB, April 19-20, 2004 Cable Supporting Slide 1 THEMIS Cable Specification