Major concerns in vacuum environments include outgassing, multipaction, and whiskering
Vacuum Challenges for Demanding Space Applications
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 (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.
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.
PhaseTrack® cable assemblies are designed for applications demanding minimal phase change over temperature. All PhaseTrack cables use a proprietary TF4™ dielectric that does not have the abrupt shift in the phase that occurs with solid- or tape-wrapped PTFE-based products under normal room ambient temperature conditions.
The SpaceFlight product line embodies the critical requirements necessary for reliable performance in space. Our proprietary material conditioning and vacuum testing of assemblies ensure outgassing is minimized to meet NASA standards ASTM E‐595.