Sandia National Labs FY20 LDRD Annual Report

FY20 ANNUAL REPORT

Developing the world’s first low-SWaP inertial sensor based on atom-interferometer technology. Atom interferometers could provide a GPS-denied solution for applications using a Size Weight and Power (SWaP) slightly larger than HG9900 but less expensive than traditional strategic grade sensors. Traditional strategic-grade inertial sensing can provide superior on-target weapon delivery but are limited in SWaP and in their ability to handle dynamics. The Strategic Inertial Guidance with Matterwaves Grand Challenge LDRD developed a sensor on path to 0.3L at a cost of less than $300k and a bias stability of 0.25 micro-g and a 20-foot circular error probability at the end of a 20-minute mission or an error growth rate of ~0.1 nautical mile/hour. The project team developed: • The first atom interferometer with a grating magneto-optical trap having a data rate of 6.7 Hz and uncertainty of ~25 micro-g. • An optical-alignment-free sensor head design, techniques to operate the atom interferometer accelerometer in a dynamic environment, and a passively pumped ultra-high vacuum package, demonstrating no degradation of the vacuum for three months and counting ... a world’s first. • A photonic integrated circuit that can provide the required control, which, when integrated

with the chip-scale optical amplifiers and frequency doublers (also under development), will provide the world’s first integrated laser system for an atom interferometer.

(PI: Grant Biedermann)

(Left) View of grating chip mountain within the draft prototype. (Right) Test fit of draft prototype into the sensor assembly within the magnetic shielding chamber.

Bringing Euclid’s imagined concept to life: Interpenetrating lattice metamaterials. Around the year 300 BC, the Greek mathematician, Euclid, imagined the geometric concept of a dual polyhedra: one 3D shape perfectly intercalating through the interstices of another without touching. Now, using modern 3D printing capabilities, an LDRD team turned these geometric concepts into reality. By tiling dual polyhedra in 3D space, these new “metamaterials” possess an array of strange and potentially useful properties, including a remarkable resistance to fracture, and an ability to electromechanically measure stress with far better sensitivity than existing sensors. The work has resulted in a provisional patent application (filed) and a paper (accepted for publication in Additive Manufacturing ). (PI: Brad Boyce)

(a) Geometric features that define interpenetrating structures, (b-f) examples of interpenetrating structures demonstrating key geometric features, (g) four body- centered cubic cells nested inside a larger tetragonal cell.

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LABORATORY DIRECTED RESEARCH & DEVELOPMENT

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