Vacuum Challenges for Demanding Space Applications

Outgassing

Many non-metallic materials outgas when exposed to a vacuum environment, including plastics commonly found in coaxial cables, such as PTFE, PVC, and PE. Emitted gases can recondense on critical components such as camera lenses, degrading performance. As a result, NASA and the European Space Agency (ESA) have developed standards to define outgassing rates and databases to compile the performance of various materials.

Multipaction

Multipaction (also known as the multipactor effect) is an electron resonance effect that occurs when RF fields accelerate electrons in a vacuum and cause them to impact with a surface, which depending on its energy, releases one or more electrons into the vacuum. When the electrons release and timing of the impacts are such that a sustained multiplication of the number of electrons occurs, it can lead to loss and distortion of the RF signal and even result in damage to the RF components or subsystems.

In RF cable assemblies, multipaction can occur at the connector between the inner and outer conductors. Our engineers mitigate multipaction risks by designing mating connectors with overlapping dielectrics to remove any free path between conductors.

Whiskering

Tin is commonly used in solder for coaxial connectors and plating of semi-rigid coaxial cables. Metals such as pure tin can grow whiskers in a vacuum and high-temperature environments, leading to shorts or FOD, and are generally prohibited from spaceflight use. To avoid whiskering, designers should specify tin/lead alloys for solder or plating.