Design of an Automation and Control System for PUPR-MC Plasma Machine

Abstract

The automation of Polytechnic University of Puerto Rico Mirror-Cusp (PUPR-MC) plasma machine is part of the work performed by the Plasma Engineering Laboratory in the experiments of the NASA Solar Probe Mission Thermal Protection Risk Assesment, executed in collaboration with Johns Hopkins University's Applied Physics Laboratory. PUPR-MC was selected for these experiments due to its capacity, both in range of operation and stability. The automation process consisted in the design of the sequence of operations to safe start-up and shutdown of the plasma device. This sequence of operations were extracted from the experience of various operators, and written into a fiowchart. The sequence was automated using a Programmable Logic Controller (PLC), working together with a set of electromechanical and electronic actuators. The PLC receives information from a vacuum measurement system and from a temperature measurement system to assess in which stage of operation PUPR-MC plasma machine is, generating the appropriate control signals. The operation can be switched from manual to automatic mode, allowing the operator to take control of the operation at any moment, if needed. The system has improved the speed and precision of the operations of PUPR-MC, by reducing the sources of human errors. PUPR-M is the only machine of its type in the Caribbean that has been setup for automatic operation.