What is a Temperature controlled Quartz Crystal Microbalance (TQCM)?

15.06.2021What is a Temperature controlled Quartz Crystal Microbalance (TQCM)?

A Temperature controlled Quartz Crystal Microbalance (TQCM) is a type of sensor which uses changes in the resonant frequency of a quartz crystal to determine the amount and rate at which mass is deposited onto the crystals surface.

A common variation on this type of sensor is used for monitoring thin film deposition processes. With the addition of a reference crystal and with thermal control, the sensor can be used for monitoring the outgassing of hardware when subject to vacuum.

A vacuum bakeout is performed to accelerate the outgassing of volatile molecules from hardware in a controlled environment, this is done to prevent contamination of highly sensitive flight equipment during operation.

Crystal Microbalance

How do we perform vacuum bakeout?

This is achieved by placing equipment into a thermal vacuum chamber under high vacuum and at elevated temperatures. The absence of atmospheric pressure and increases in the kinetic energy of particles due to heating, provide the correct conditions for volatile molecules to be emitted from the surface of the equipment.

With AEON’s expertise and one of a kind facility we have been able to design, build and commission our own thermal vacuum chamber dedicated to performing the bakeout process for flight hardware to ECSS standards.

This knowledge and experience means we are able to have greater control over the bakeout process by fine-tuning pressure and temperature profiles throughout, even to the extent of being able to preferentially increase or decrease the heating of equipment in different areas to accommodate especially sensitive equipment.

It is important to note that these volatile molecules are commonly found in both raw materials as well as any applied finished. The exact chemical composition will be dependant of the materials used, and will have different affects if not removed, but generally will have a negative impact on electrical sensors, optics, and cryogenic systems. Ultimately, the vacuum bakeout process assures that the end-product will function as required.

Crystal holder for TQCM

Interested in learning more about TQCM?

AEON have dedicated a separate article to how the Temperature controlled Quartz Crystal Microbalance (TQCM) works, they felt it deserved it's own feature and to go into length of the process and requirements for such a technical piece of equipment.

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For further details on AEON’s bakeout facility or TQCM systems you can discover more in our brochure.

AEON supply TQCM's for thermal bakeout chambers, enquire here about purchasing your own.