• Hall thruster
• electric propulsion
• control system
• arduino
• python
• alternative propellants
• iodine

Nowadays, xenon and krypton are the only used propellant in all operational satellites equipped with Hall and ion thrusters. Xenon presents several qualities that are advantageous for electric propopulsion applications, including a high atomic mass, low first ionization energy and a large ionization cross section, all of which contribute to a more efficient plasma creation than alternative possibilities. However, because of its growing use in a variety of high-tech industries, its supply and price fluctuate a lot, making it difficult to be used in a space project. Krypton has a higher availability and a lower cost, as well as the ability to adapt to systems originally designed for xenon use. However, compared to xenon, krypton adoption results in a loss of thrust efficiency and a lower storage density. Noble gases have a further disadvantage: their supercritical storage conditions necessitate a high-pressure tank, a pressure regulating system and a distribution system to deliver the gas at low pressure into the thruster discharge chamber. Due to its higher storage density, lower cost and comparable performance, iodine could represent a valid alternative, especially in volume-constrained applications. The University of Pisa is currently developing an iodine feeding system for generating iodine vapor from solid iodine, for use as a propellant in a Hall Effect propulsion system. The architecture of the feeding system consists of a sublimation body thermally regulated to sublimate iodine at the desired vapor pressure, an on-off valve, a laser-based flow meter, which measures the light absorbance of the iodine flow allowing to infer the mass flow rate instantaneous value, and a thermal throttle, which finally performs a fine mass flow rate control. The present thesis deals with the design and the development of an integrated control unit able to regulate the mass flow rate through the thermal control of the sublimation body and the thermal throttle. This has been realized using open-source technologies, which offer some key advantages over licensed technologies in terms of cost reduction, speed of development and ease of use. Besides the thermal regulation, the control system must fulfil other tasks like the activation of the valve, the flow meter reading as well as the failures detection. Different architectures are analysed and a calibration methodology is presented. This work was accomplished in conjunction with the creation in Python of a graphical user interface for monitoring and controlling purposes.