KIRTLAND AIR FORCE BASE, NM (AFRL) — scientists and engineers Air Force Research Laboratory develop a multi-energy electron source capable of emitting an electron beam with dozens of energies simultaneously.
In a Department of Defense funded project, the multi-energy electron device was developed by Dr. Miles Bengtson while he was a graduate student at the University of Colorado Boulder. After graduating in 2020, Bengtson was offered a postdoctoral position at the AFRL Space Vehicles Directorate’s Spacecraft Charging and Instrument Calibration Lab (SCICL) with the goal of bringing the multi-energy electron tool from proof-of-concept to operational status.
Objects in space are exposed to the harsh space environment, which consists of high-energy electron and proton radiation and several other factors such as ultraviolet light, temperature changes, and harsh vacuum, which can affect spacecraft performance.
“AFRL researchers have long studied how spacecraft materials and components degrade and evolve over time in the space environment, and have developed technologies to ensure spacecraft meet their mission lifetimes despite prolonged operation in this extreme environment,” said Bengtson .
To investigate materials, experiments are often carried out in vacuum chambers in which material samples and components are exposed to energetic electron beams from a so-called electron source.
“The problem is that traditional multi-energy electron devices are just monoenergetic — they only emit electrons at one energy — while the space environment contains electrons distributed across all energies simultaneously,” Bengtson said. “As a result, the environment in which spacecraft materials and components are tested is fundamentally different from the environment in which they operate.”
AFRL’s multi-energy electron device will give researchers the ability to create an energetic electron environment in a laboratory that closely resembles the actual space environment.
“The testing capabilities we have developed at AFRL will enable scientists, designers and manufacturers to conduct ‘test as you fly’ studies of how materials respond to energetic electron beam irradiation,” said Bengtson. “The ability to recreate the electron flow environment in space with high fidelity in a laboratory is an enabling technology for a variety of Air Force and Space Force requirements, as well as for commercial purposes.”
Several applications feature the use of a multi-energy electron device.
- Laboratory testing allows for accelerated adaptation of novel/advanced materials for use in spacecraft, as relying only on historical materials hampers agile implementation of next-generation materials.
- It will provide a useful tool for studying material evolution, electrical charge and electrostatic discharge on satellites and how interactions with the space environment can lead to satellite anomalies.
- Understanding how materials evolve over time is critical to developing next-generation space domain perception tools.
Bengtson shared an example of how understanding of materials used in spacecraft is aided by this technology.
“The Spacecraft Charging and Instrument Calibration Lab is investigating how satellite reflectance spectra can be used to remotely and passively characterize objects in space,” said Bengtson. “For example, the object called 2020SO was originally thought to be an asteroid passing close to Earth. However, by analyzing the spectra of sunlight reflected from the object, further investigation determined that it was made of stainless steel and not asteroid material. This led to the realization that the object was actually a spent Gemini-era Centaur rocket body,” Bengtson said, noting, “The multi-energy device allows for a detailed study of how reflectance spectra change with time in orbit, which was crucial for this endeavor. ”
Ryan Hoffmann directs SCICL and is proud of the technological advances his laboratory has made in studying spacecraft materials to improve satellite robustness and resilience and to develop space awareness tools.
The 5,000 square meter laboratory contains three large vacuum test chambers named Mumbo, Jumbo, ExB Magnetized Plasma Device; a mid-vacuum chamber called the MiniMum; and two bell jars, one used to test cover slips for solar panels under electron beam irradiation and the other used to measure the resistivity of space materials.
“SCICL is a world-class research laboratory, and our exploration of this multi-energy electron source is an example of the progress AFRL is making in studying the space environment on spacecraft,” said Hoffmann. “Our team is at an advanced prototype stage in the development of the multi-energy electron device. I am happy to say that we have built two prototypes so far that have demonstrated basic functionality and are now building an advanced prototype that will come very close to a fully working model.”
The Air Force Research Laboratory (AFRL) is the primary scientific research and development center for the Department of the Air Force. AFRL plays an integral role in leading the discovery, development and integration of affordable warfare technologies for our air, space and cyberspace forces. With more than 11,500 employees in nine technology areas and 40 additional operations around the world, AFRL offers a diverse portfolio of science and technology, ranging from basic research to advanced research and technological development. For more information visit: www.afresearchlab.com.