1

2 1-Meter Cross-Coil Prototype The mechanical design was driven by two primary requirements; to Improve the mechanical precision in the placement and alignment of the coil elements, and, to provide a robust, integrated instrument package appropriate for field testing. Receiver coil arrays Z coil pair X coil pair Y coil pair Assembled instrument

3 The 1-Meter Prototype currently under construction integrates precision winding forms and assembly features with structurally efficient panel assemblies Coil form assembly prior to winding the transmitter coils. Panel construction concept showing indexing features and assembly exploded view Coils are shown here as an example of the final coil location after assembly. The X and Y coils are actually wound onto the assembled cross panels as a sub- assembly Z transmitter coils and Receiver arrays are wound and assembled as separate panels..

4 The Receiver coils are wound on mandrels that become integrated into panels that includes electrostatic shielding. The transmitter coils are wound on machined coil forms as matched pairs. X and Y coils are wound in place on the assembled coil forms The panels are assembled into the instrument cube using indexing features machined to insure robust alignment and stability. Receiver panel Z transmitter panel X transmitter pair Wound as mirror-image duplicates Z transmitter panel Receiver panel Y transmitter pair Wound as mirror-image duplicates

5 Electrostatic shielding is integrated into each coil panel unit during panel fabrication. Core and skin materials are non- conductive and non-magnetic. Shields are etched copper on kapton and are applied to the panel skins. The final package is an integrated panel with the coil elements locked in their relative positions. Transmitter panels are assembled in similar fashion with the coils wound directly onto machined surfaces in the panel coil form..005” thick shields on the outer panel skins Receiver coil on mandrel Skins and Core Cutaway view of a Receiver panel

6 The field test configuration features a light weight carriage assembly With provision for GPS antenna and calibration hardware.

7 Here, the carriage assembly is shown without the detector coil. The GPS antenna is shown in it’s relative location. The Field-ready cart concept including bumpers, electronics and laptop computer. The electronics were later moved inside the beam structure. There is also a ‘tailwheel’ option not shown here

8 Proof-of-concept model parts have been cut by waterjet and are being dry-fitted into coil form sub assemblies. Here, the X and Y Transmitter assembly is being wound

9 The transmitter assembly is complete and is wired into the field electronics for check out and diagnostics Meanwhile, the Receiver panels are getting their last internal hookups before being laminated into structural panels. In this picture, the receiver coils are embeded in the foam panels. The shield circuitry is being completed. The next step willl be to add skins and laminate the assembly to become the receiver panel.

10 A word about the process….. Design around the Waterjet process allowed several huge advantages including speed, cost, and accuracy. It also allowed rapid iteration at modest cost. The simplicity is illustrated here. Pre-laminated composite panels are cut to precise profiles on the Waterjet. Parts are immediately available for dry-fit and tolerance checks. Assembly follows with parts snapped into place and epoxy bonded. No fixtures or tooling was used.

11

12