Technical Digest

The Concept Design and Realization Branch within APL’s Research and Exploratory Development Department provides an array of engineering, design, and fabrication capabilities that broadly support the Laboratory’s mission and sponsored work. It has been more than 20 years since these areas have been reviewed in this publication, and during that time, the Lab’s ability to develop and build complex systems has advanced significantly. Computing power has exponentially advanced the enabling modeling, analyses, machine programming, and novel manufacturing methods—many of which were unimaginable 20 years ago. Electronics, sensing, artificial intelligence, and other technologies have merged and are increasingly embedded to create powerful automated tools. Today, the branch continues to serve the Lab with hardware design, mechanical and electrical fabrication, systems integration, and breakthrough manufacturing science that will benefit the programs and missions of the future. This issue, the first of two, describes examples of the wide-ranging work of the branch, highlighting how it directly contributes to APL’s position as a unique resource to the nation.

The Johns Hopkins University Applied Physics Laboratory (APL) has been developing, fabricating, and testing complex electronic, electromechanical, and mechanical systems from its very beginning. Although the underlying organizations, facilities, and technologies have evolved over this time, in some cases dramatically, the ability to advance ideas from concepts to realized hardware remains one of APL’s core distinguishing capabilities, supporting a wide variety of diverse programs and projects across the organization. Throughout APL’s history, a key enabler of these concept-to-realization capabilities has been the Laboratory’s enterprise design, engineering, and fabrication operations. This article briefly traces the history of these functions and their impact on numerous noteworthy achievements of APL. Today, these areas are unified as the Concept Design and Realization Branch within the Research and Exploratory Development Department. The branch continues to serve APL, its sponsors, and the nation with hardware design, mechanical and electrical fabrication, systems integration, and breakthrough manufacturing science that will benefit the programs and missions of the future.

The Johns Hopkins University Applied Physics Laboratory (APL) has been instrumental in developing stratospheric ballooning for scientific research. Our contributions include systems for unprecedented pointing accuracy and stability that have enabled missions that would otherwise be impossible. In addition, we have engineered systems for avionics, power, software, command and control, ground support, integration, and testing. APL staff members have worked in the field to integrate, troubleshoot, and operate the balloon systems. These accomplishments have supported innovative space science missions in heliophysics, astrophysics, and planetary science.

In 2017, APL’s Jovian Energetic Electrons (JoEE) spectrometer team finalized its innovative design for the instrument, slated for the European Space Agency’s JUpiter ICy moons Explorer (JUICE)—the first mission to orbit an icy moon. However, the curved collimator design pushed the limits on traditional manufacturing techniques, and the most viable method, additive manufacturing, faced significant hurdles for acceptance. Engineers, scientists, and machinists from across the Johns Hopkins University Applied Physics Laboratory (APL) brought their expertise together to address challenges ranging from unexpected machine behavior to unreliable inspection methods to ultimately qualify and launch. By testing and refining metal additive techniques and collaborating internally and with external partners, they were able to achieve the complex geometries required for the collimator and successfully develop, qualify, and launch the flight collimator—APL’s first additively manufactured flight component—in just 2 years.

The Johns Hopkins University Applied Physics Laboratory (APL) is working to realize a variety of nanostructured designs via top-down nanofabrication techniques. We leverage electron beam lithography, nanoimprint lithography, and focused ion beam deposition to pattern nanoscale features on semiconductor and optical material substrates. We combine these with other traditional microfabrication techniques as well as a few unique ones, including an atomic layer deposition–enabled nanomolding process to create high-aspect-ratio nanopillars from materials such as titanium dioxide (TiO2 ). We apply these techniques on a wide variety of nontraditional substrate and film materials, including optical, phase-change, and superconducting materials, to create novel optical and electronic devices.

The metal additive manufacturing (AM) process uses high-power lasers to rapidly melt and solidify metal powder into complex 3-D shapes, but unfortunately the rapid solidification process often results in stochastic defect formation and nonequilibrium microstructures. To fully understand the AM process and ensure a high-quality, defect-free manufacturing process, novel high-speed sensing methods that can capture key physical phenomena associated with the AM process at high resolution are needed. A team at the Johns Hopkins University Applied Physics Laboratory (APL) is developing novel spectrometry techniques capable of measurement speed exceeding 50 kHz along the laser path to aid in understanding how materials are formed under different laser inputs. The team is also developing machine learning tools to interpret these signals, thus revealing features and trends that are not apparent to human analysts in the sensor data or physical postmortem inspection results of the printed components.

A phased array is a directive, electronically steered antenna consisting of multiple antenna elements wherein each element’s signal has a unique phase shift applied so that the combined phase-shifted contributions from each element form an antenna beam in the desired direction for both transmission and reception. Phase shifting and beam formation had been performed using analog components outside of the radio transceiver until the advent of digital signal processing introduced digital beamforming. With digital beamforming, the signal from each antenna element is connected directly to an analog to digital converter (ADC) input of a multichannel transceiver. The phase shifting and combining is performed during the digital processing, allowing for fast beam hopping and complex beam pattern generation. However, multiple ADCs can be costly in terms of size, weight, and power (SWaP) and overall complexity, particularly as the number of elements in the phased array increases. This article describes the development, fabrication, and testing of a new type of digital beamforming phased-array antenna system by researchers at the Johns Hopkins University Applied Physics Laboratory (APL). The system frequency-multiplexes the signal from multiple antenna elements onto a single analog line, offering potential solutions for applications where cost and size are of concern. This system can also operate as a coherent multichannel transceiver, offering similar cost and size savings. This project, which progressed from concept to hardware to successful field testing in less than a year, exemplifies the results that APL—leveraging its multidisciplinary teams, worldclass engineering expertise, and state-of-the-art fabrication facilities—is able to achieve.

This article describes Johns Hopkins University Applied Physics Laboratory (APL) capabilities in computational engineering and design for additive manufacturing. Because additive manufacturing’s selective deposition of material and energy enables the ability to produce new and novel geometries, designers and fabricators need new design software and validation methods to take full advantage of this new fabrication technology. APL employs an immense range of modeling, optimization, and finite element modeling software to unlock the true potential of additive manufacturing. By combining these AM-specific computational engineering design tools with its diverse expertise in areas such as rapid material development, the Lab can fabricate novel components with unprecedented properties for its sponsors’ unique missions.

Atomic and molecular modeling techniques have developed over the past 75 years into a vibrant field of computational science, used to understand and predict materials properties and phenomena in academic, industrial, and government labs. Researchers today have the benefit of decades of Moore’s law growth in computer processors, decades of algorithm and software development, experiments capable of atomic-scale characterization for validation, and a deeper understanding of the strengths, limitations, and complementary features of different computational methods. It is not surprising then that important problems in many fields—battery chemistry, drug design, mechanics of materials, biocompatibility, and catalyst design—are routinely studied using atomic-scale simulation and modeling. In this article, we first outline a brief history and background of the density functional theory and molecular dynamics methods. Next, we discuss several case studies that exemplify how scientists and engineers at the Johns Hopkins University Applied Physics Laboratory (APL) use these computational methods to attain APL’s broader goals and mission. Finally, we discuss future directions for atomic-scale modeling and calculations, such as integration with modeling methods at other scales and with artificial intelligence–enabled frameworks, to meet the next generation of sponsor challenges.

This article discusses how researchers at the Johns Hopkins University Applied Physics Laboratory (APL) are using computational fluid dynamics (CFD) to address public health and safety concerns. CFD, a numerical prediction tool used to simulate fluids, can aid in the design and engineering process by providing insight without the need to physically build or observe a system. Here we present two applications in the public health domain. The first application models and predicts the spread of aerosols in operating rooms in response to the coronavirus disease 2019 (COVID-19) pandemic. The insight derived from this modeling will enable the design of next-generation operating rooms that offer better control of airborne contaminants. The second application focuses on modeling and evaluating the impacts of hurricanes by integrating numerical weather prediction and damage prediction modeling tools. The insight gained from these hurricane simulations enables evaluation of the potential risks and benefits of hurricane modification technology and a greater understanding of the threat of severe storms as a consequence of climate change. From hospitals to hurricanes, the modeling and simulation of fluids can enable insights to inform public health and safety.

The COVID-19 pandemic upended normalcy around the world, particularly in the workplace. At the Johns Hopkins University Applied Physics Laboratory (APL), staff members in the Concept Design and Realization Branch had to adjust their work practices to prevent disease outbreaks while continuing to design and fabricate critical components for diverse missions. In addition to adhering to Labwide safety measures such as social distancing and cleaning protocols, the design and fabrication teams modified their workstations and processes; adjusted work schedules; adhered to expanded cleaning protocols; and leveraged digital communication and collaboration tools to ensure continuity of operations. As the pandemic has waned, some of these measures have been phased out. However, some of these tools and practices have proven to be highly valuable under normal operations and have become part of the new normal. Using these tools and methods, the design and fabrication teams successfully delivered major projects over the course of the pandemic, demonstrating resourcefulness, adaptability, and commitment in the face of difficulty.

Again this year, the Johns Hopkins University Applied Physics Laboratory (APL) celebrated the exceptional accomplishments of its staff members. APL introduced its awards program in 1986 to recognize staff members’ best publications; over the ensuing decades, the program has expanded to recognize extraordinary achievements of all sorts—from exceptional work in both sponsored programs and independent research and development, to the most successful inventions and the greatest analytical achievements, to significant contributions that enhance operations and culture at the Laboratory. The 2022 APL Achievement Awards, honoring work from 2021, continued a practice that was introduced in 2020 during the COVID-19 pandemic: a safe and fun virtual format. This article details the awards and prizes presented to APL staff members in 2022 for their exemplary work in 2021.