Thermal vacuum testing is performed on a wide variety of materials, devices, and systems to either evaluate the test subjects in a simulated space environment or to condition the subjects in a space-like environment. This is a critical stage in the burn-in, break-in, or conditioning of a wide range of materials and RF devices/systems. This is also a critical tool for evaluating materials and construction methods for their viability in space or low-pressure environments.
A thermal vacuum chamber is simply a sealed vacuum chamber that has some method of precisely controlling the internal radiated temperature using cooling or heating. As the environment inside is extremely low pressures, any outgassing or material degradation that results in fluid or gas leaks can be detected. Knowing the outgassing potential or material degradation that results in liquid, gas, or particulate leaks or emissions is essential in precision sealed environments, as these undesirable contaminants can potentially damage, degrade, or even destroy other components sensitive to contamination within the sealed environment.
Thermal vacuum chambers are also useful for prototype or developmental testing of electronics and other hardware components including coaxial cable assemblies. Within a strong vacuum there is very little atmosphere to interact with electrical and electronic components, and it may be a more desirable environment in which to perform burn-ins or life-cycle testing.
Beyond space testing, it may also be useful for testing aerospace materials and hardware in a thermal vacuum chamber, as the environment inside can be precisely controlled enough to simulate high altitudes as well. This could apply to manned and/or unmanned systems.
There are also other phenomena of concern to electrical and electronic systems outside of outgassing while in low pressure environments. One of these is multiplication, multipactor effect, or multipactor discharge. This occurs in an RF environment at very low pressures, where under certain conditions a secondary electron emission within resonance with an alternating field can lead to electron multiplication. In other words, an electron avalanche can occur in vacuum or very low pressure where electron collisions induced by RF fields can lead to additional electrons being emitted and accelerated by the RF EM fields. If the conditions are right, the electron avalanche can grow exponentially and lead to substantial electron discharges that could damage sensitive RF electronics or even vaporize dielectric or conductor materials within an RF environment. If this occurs within an RF transmission line, such as a coaxial cable assembly, the ionized gas particles created by the vaporization could collect within the RF transmission line and lead to ionization breakdown.