CU Aerospace (CUA) and the Univ. of Michigan (UM) propose the continued development of the Cycle Automated Mass Flow (CAMFlow) system for reliable and well-regulated flow control. CAMFlow uses an innovative control scheme that enables stable operation using only Boolean valve states, even for the low flow rates necessary for sub-kW Hall thrusters. This methodology removes system complexity and places the onus of reliability almost entirely on valve cycle life. Throttling, open and closed-loop operation, as well as hard startup/shutdown in closed loop mode were all successfully demonstrated with the CAMFlow system with a Hall thruster at UM facilities during the Phase I effort. Phase II CAMFlow units will be focused towards smaller Hall-effect or gridded-ion electric propulsion systems having a flow rate in the 0 – 5 mg/s range, however the technology is applicable over a larger range of flow rates for a broader commercial market. The system will be designed and fabricated with size, functionality, risk tolerance, and cost considerations appropriate for NASA Class-D missions. The Phase II effort has the dual focus of extensive reliability/performance testing and the design, assembly, acceptance testing, and delivery of a compact integrated Phase II system ready for flight integration. The successful Phase I demonstrations of stable operation at target performance levels lead to the design of the Phase II CAMFlow system test hardware, thermal modeling, production, acceptance testing, environmental validation testing, and delivery of a flight-like CAMFlow system (TRL 6) at the end of Phase II. CUA will also develop a brassboard Propellant Management Assembly (PMA) with a best effort goal of achieving a flight-like PMA.
CAMFlow systems can support NASA applications by directly enabling compact gas fed systems including lower power Hall effect thrusters in Class-D missions. NASA missions that could potentially benefit from our compact CAMFlow systems would generally require very high total impulse using Hall or ion thrusters. Such missions include near-Earth objects, inner Solar System, and Outer Solar System. A good example is the Psyche mission. The compact CAMFlow system designed for CubeSats and small satellites is easily scalable to larger sizes.
Aside from the general application of gas-fed propulsion systems, CAMFlow can also enable some unique ground testing opportunities. With open and closed loop control, along with the potential to use process variables aside from pressure, CAMFlow can help aid in the development of alternative control schemes a wide variety of fluid flow systems.