Researchers at theMassachusetts Institute of Technology(MIT) have used 3D printing to create unique plasma sensors with the potential to help scientists better understand the impact of climate change.
Compared to traditional weather-monitoring sensors, the team’s laser cut and 3D printed alternative can be produced outside of cleanroom conditions, reducing its lead time from weeks down to just a few days. This, alongside their relatively low manufacturing cost, could make the devices ideal for fitting to CubeSats, where they can monitor temperature fluctuations in Low Earth Orbit (LEO).
“Additive manufacturing can make a big difference in the future of space hardware,” says MIT Principal Scientist, Luis Fernando Velásquez-García. “Some people think that when you 3D print something, you have to concede less performance. “But we’ve shown that is not always the case. Sometimes there is nothing to trade off.”
Making monitoring more accessible
When it comes to monitoring changing weather patterns in LEO, retarding potential analyzers (RPAs) are a vital piece of equipment. First deployed in a space mission in 1959, these multi-electrode instruments essentially detect the energy in the ions that float in the plasma molecules present in the Earth’s upper atmosphere. Also applied as in-orbit mass spectrometers, the versatile sensors are capable of measuring energy and analyzing chemicals to inform weather predictions.
RPAs themselves work by using a series of electrically-charged meshes with tiny holes to strip electrons and other particles away from ions, which in turn, create a current that can be measured and analyzed. According to the MIT team, making such devices effective depends on ensuring their housing structure and meshes align, as well as their insularity and ability to withstand drastic temperature swings.
However, the scientists also point out that current plasma sensors tend to be made from silicon in cleanroom conditions, via a process that requires weeks of intricate fabrication. As such, RPAs can be very expensive, limiting their potential to be fitted to the CubeSats that are increasingly making LEO-based R&D more accessible. With this in mind, the MIT team have developed a means of 3D printing them from glass-ceramic instead, that could help advance in-situ ionospheric studies.
“如果您想创新，则需要能够失败并承受风险。添加剂制造是制造空间硬件的一种截然不同的方法。”Velásquez-García解释说。“我可以制作太空硬件，如果失败，那没关系，因为我可以非常快速，廉价地制作新版本，并且可以在设计上确实迭代。这是研究人员的理想沙箱。”
“当您在洁净室中制作该传感器时，您没有相同程度的定义材料和结构以及它们如何相互作用的自由度。使这成为添加剂制造中的最新发展。”
引入3D打印的“ RPA”传感器
该团队重新设计的传感器的核心是一个激光切割，五电极堆栈，内部是3D打印的玻璃陶瓷电极外壳和CNC加工的裹尸布。实际上，外壳设计为使用一组与一组偏转弹簧相互作用的凹槽在空间上分发电极。也就是说，研究人员实际上探索了两个不同的堆栈设计，其中所有孔径均为相同的大小，而另一个孔则与“浮动网格”形成中的单个光圈匹配。
两者都是使用一个特森3D野牛1000system and Vitrolite, a durable pigmented glass capable of withstanding temperatures of up to 800°C, and designed with hexagonally-packed apertures, to maximize the number that could be fitted in. For each RPA design, the aperture size was also optimized via finite element analyses, in an attempt to achieve optimal ion transmission across the device’s grid.
Once ready, the team subjected their prototypes to ion energy distribution simulations and practical testing via electron impact ionizer and helicon plasma testing. In the former, both designs proved able to accurately estimate the average energy of ions, but in practical evaluations the devices showed potential in different application areas.
实际上，统一的网格设计在测量各种等离子体方面特别有效，类似于卫星在轨道中通常会遇到的等离子体。但是，另一个具有浮动网格对准，事实证明，它非常适合感知密集和冷的等离子体，精度仅为50 µm，通常只能使用超精美的半导体设备来测量其中。
鉴于测试揭示了他们的设备可以“与最新的状态相提并论”，研究人员得出结论，他们具有巨大的潜力，以促进可及的天气监测。向前迈进，团队甚至认为，Binder Jet 3D打印可以用于生产更多RPA的零件，从而可以减少其质量并提高其性能。
Entering an era of 3D printed CubeSats
Additive manufacturing continues to find widespread satellite applications, not just in the creation of ancillaries, but of the casings of the devices themselves.机器人, for instance, has partnered with theUniversity of Colorado Boulderto3D print a weather-monitoring CubeSatdesigned to analyze the electromagnetic waves caused by lightning strikes.
AlongsideAlba Orbital和迷你立方体,CRP Technology还不断使用其Windforf XT 2.0材料3D print pocket satellites and deployers. Working with the former, the firm previously deployed the technology and its carbon fiber composite to reduce the weight of the ‘Alba 2’ PocketQube deployers by 60%.
On a more commercial level, Franco-Italian aerospace manufacturerThales Alenia Space继续使用卫星系列制作中的3D打印. In fact, just last month, the firm announced plans to work with start-upMIPRONSto develop a novel3D printed water-fuelled satellite thruster具有增强的机动性。
The researchers’ findings are detailed in their paper titled “Compact Retarding Potential Analyzers Enabled by Glass-Ceramic Vat Polymerization for CubeSat and Laboratory Plasma Diagnostics,” which was co-authored by Javier Izquierdo-Reyes, Zoey Bigelow, Nicholas K. Lubinsky and Luis Fernando Velásquez-García.
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特色图显示了研究人员的3D打印等离子传感器。通过麻省理工学院的照片。
