CU Aerospace (CUA) and the University of Michigan (UM) propose the 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-kilowatt Hall effect thrusters. This methodology removes system complexity and places the onus of reliability almost entirely on valve cycle life. The CAMFlow control scheme was successfully implemented in CHIPS, a TRL 5 warm gas thruster produced by CUA through previous NASA SBIR work. As a result, design tools and calculators are already in place for the development and tuning of a system for low flow rate xenon. Phase I and future 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 broadly 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. In Phase I, a breadboard system will be fabricated and tested by CUA, followed by integrated Hall thruster testing and validation at UM. CUA anticipates delivering to NASA an integrated flow control system by the end of Phase II.
CAMFlow systems can support NASA applications by both directly enabling gas fed systems including lower power Hall effect thrusters in Class-D missions. CAMFlow is already implemented in the CUA CubeSat High Impulse Propulsion System (CHIPS), providing constant pressure feed while the thruster switches between cold and warm gas modes, and fires up to 4 attitude control thrusters. Depending on tuning, a standalone CAMFlow systems can provide steady, regulated flow for primary propulsion and other mission critical devices.
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.