Tech Briefs Magazine - May 2023 - 36

Test & Measurement
Multi-Energy Electron Device to Enable Lab Testing of
Spacecraft Materials
The device will give researchers the ability to produce an energetic electron environment
in a laboratory.
Air Force Research Laboratory, Rome, NY
E
ngineers at the Air Force Research
Laboratory are developing a multi-energy
electron source, capable of emitting
a beam of electrons, at dozens of energies
simultaneously.
In a project funded by the Department
of Defense, the multi-energy
electron device was invented by Dr.
Miles Bengtson during his tenure as a
graduate student at the University of
Colorado Boulder. Following graduation
in 2020, Bengtson was offered a
postdoctoral position at the AFRL
Space Vehicles Directorate's Spacecraft
Charging and Instrument Calibration
Lab, or SCICL, with the goal of
bringing the multi-energy electron
tool from proof-of-concept to operational
status.
Objects in outer space are subjected to
the harsh space environment, which
consists of energetic electron and proton
radiation, and several other factors
such as ultraviolet light, thermal cycling
and hard vacuum, which may degrade
the performance of the spacecraft.
" Researchers at AFRL have long been
studying how spacecraft materials and
components degrade and evolve over time
in the space environment, and have developed
technologies to help ensure that
spacecraft will fulfill their mission lifetimes,
despite prolonged operation in this
extreme environment, " said Bengtson.
To test materials, experiments are often
conducted in vacuum chambers in which
material samples and components are exposed
to energetic electron irradiation
from a device known as an electron source.
" The problem is that conventional
multi-energy electron devices are monoenergetic
only - they only emit electrons
at one energy - whereas the
space environment contains electrons
distributed across all energies, simultaneously, "
Bengtson said. " Therefore,
the environment where spacecraft materials
and components are tested is
fundamentally different from the environment
they operate in. "
AFRL's multi-energy electron device
will give researchers the ability to produce
an energetic electron environment
in a laboratory, which closely represents
the actual space environment.
" The test capabilities we have developed
at AFRL will provide scientists, developers,
and manufacturers the ability to perform
'test like you fly' studies of how materials
respond to energetic electron irradiation, "
Bengtson said. " The ability to recreate the
space electron flux environment with high
fidelity in a laboratory, is an enabling technology
for a variety of Air Force and Space
Force needs, as well as commercial needs. "
The multi-energy electron device will
enable laboratory testing accelerating adaptation
of novel/advanced materials for
use on spacecraft since relying only on heritage
materials hinders the agile implementation
of next-generation materials. It
will provide a useful tool for studying material
evolution, electrical charging, and
electrostatic discharge on satellites, showing
how interactions with the space environment
can lead to satellite anomalies.
For more information, contact afrl.
pa.inquiry@us.af.mil.
An Accurate, Low-Cost Tool for Forest Measurement
An algorithm that uses computer vision techniques provides more accurate and faster results
than manual measurement techniques.
University of Cambridge, United Kingdom
T
he researchers from the University of
Cambridge have developed an algorithm,
which gives an accurate measurement
of tree diameter, an important
measurement used by scientists to monitor
forest health and levels of carbon sequestration.
The algorithm uses lowcost,
low-resolution LiDAR sensors that
are incorporated into many mobile
phones, and provides results that are just
as accurate, but much faster, than manual
measurement techniques.
The primary manual measurement used
in forest ecology is tree diameter at chest
36
height. These measurements are used to
make determinations about the health of
trees and the wider forest ecosystem, as well
as how much carbon is being sequestered.
While this method is reliable, since the
measurements are taken from the ground,
tree by tree, the method is time-consuming.
In addition, human error can lead to
variations in measurements.
" When you're trying to figure out how
much carbon a forest is sequestering, these
ground-based measurements are hugely
valuable, but also time-consuming, " said
first author Amelia Holcomb from Camwww.techbriefs.com
bridge's
Department of Computer Science
and Technology. " We wanted to know
whether we could automate this process. "
Some aspects of forest measurement can
be carried out using expensive special-purpose
LiDAR sensors, but Holcomb and her
colleagues wanted to determine whether
these measurements could be taken using
cheaper, lower-resolution sensors, of the
type that are used in some mobile phones
for augmented reality applications.
Other researchers have carried out some
forest measurement studies using this type
of sensor, however, this has been focused
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