Design and development of iodine flow control systems for miniaturized propulsion systems

The high density of iodine, and its storage in solid form with no pressurization requirements, have driven the increase on the use of the halogen for space propulsion systems. This paper presents the design and development process of a miniaturized propellant management system which can supply iodine at a stable mass flow rate to the thrusters. This system approach has been adapted to produce the flow control units of the NPT30-I2 gridded ion propulsion system and the I2T5 cold gas thruster, both of which have performed their first in-orbit demonstration flights. The paper is dedicated to the description of the design process, with a focus on the particularities of the use of iodine for space propulsion systems, mainly related to chemical interaction and deposition. The numerical analysis of rarefied flows serves as a base for the design of the flow path elements of the system. A performance characterization of the system obtained on ground and the challenges tackled during the development process are evaluated with the in-orbit data from the first flight missions of both propulsion systems.