Mark 18 Cryogenic Quartz Crystal Microbalance from QCM Research
Quartz crystal microbalances (QCMs) are devices used to measure the rate of mass deposition per unit area by correlating changes in the measured frequency of an exposed quartz crystal resonator to a corresponding change in crystal mass. For testing of electric propulsion devices, QCMs are most often used to quantify the deposition rate of material (e.g., graphite) sputtered from the grids of an ion engine and/or any exposed chamber surfaces (e.g., the beam dump) by the high-energy beam ions. This deposition rate can be used to assess device lifetime by quantifying the erosion rate of the ion engine grids or correcting Hall thruster channel erosion measurements to account for deposition of sputtered material from the facility. It can also be used to quantify contamination from these sputtered materials.
Mark 18 QCM installed in VTF-2
HPEPL uses an industry-standard, turnkey QCM system manufactured by QCM Research. The system is composed of a Mark 18 cryogenic QCM controlled by a M2000 Control/Data Acquisition Unit that permits real-time data acquisition via RS-232 serial link and a complete manufacturer-provided software package. This system can withstand temperatures between -199°C and 100°C and is thus compatible for use during cryopump operation in VTF-2. More information on this system can be found on the manufacturer website: http://www.qcmresearch.com.