Passive Two-Phase Thermal Management System for Hall Thruster

Advanced Cooling Technologies, Inc. (ACT) proposes to develop and mature a lightweight, compact, and highly effective passive two-phase thermal management system (TMS) for extremely high power-density commercial magnetically-shielded Hall thrusters, aiming to enable NASA for its future cislunar and deep space missions. In Phase I, ACT performed a comprehensive heat pipe design trade study and developed two unique three-dimensional alkali metal heat pipe prototypes for 20 kW H9 Hall thrusters. Both heat pipe prototypes outperform the heat transfer requirement obtained in finite-element simulations by up to five times and can operate in any orientation irrespective of the presence or absence of electromagnetic fields. Passive two-phase HPs are integrated with a small hot radiator, being in radiative heat transfer with downstream while a relatively larger cold radiator attached to the back of the H9 Hall thruster, protects the temperature-sensitive components from overheating. Based on FEA, ACTs innovative passive two-phase TMS could decrease traditional cold radiator of a 20 kW H9 thruster by up to 40% in size and 1 kg in mass. In Phase II, followed by continuing to further optimize and mature the passive two-phase TMS, ACT will integrate its passive two-phase TMS on UMich. H9 Hall thrusters and experimentally measure thrust, efficiency, specific impulse, current oscillation etc. inside a large vacuum chamber. The final deliverable will be a passive two-phase TMS, consisting of down-selected heat pipes, hot and cold radiators. Hall thrusters are one of the most successful and widely flown forms of electric propulsion with moderate thrust density (10 N/m2) and high specific impulse (1500-3000 s). While modern magnetically-shielded Hall thrusters (1-9 kW) are designed to be passively cooled through the radiation of waste heat, temperature-sensitive components begin to de-magnetize and overheat beyond 9 kW. Advanced Cooling Technologies, Inc. (ACT) is developing a robust passive two-phase thermal management system (TMS) to enable Hall thrusters to operate at extremely higher power-densities (20-100 kW). Multiple high-temperature heat pipes (HPs) extract the waste heat from inside the Hall thruster and deliver it to their small hot radiator, where it emits the heat to downstream. A light, compact, and highly-efficient cold radiator attached to the back of the Hall thruster, also protects the temperature-sensitive components inside thruster from thermal and material failures. The overall objective is to develop a robust, light weight and efficient two-phase thermal management system (TMS) that will enable Hall thruster to operate with significantly higher power density. In Phase I, ACT successfully designed a passive two-phase TMS for a 20kW H9 Hall thruster and demonstrated feasibility and power scalability through prototype testing and simulation. In Phase II, ACT will collaborate with the University of Michigan and Busek to further mature the passive two-phase TMS and identify appropriate manufacturing and assembling processes with Hall thrusters. Both hot side and cold side TMS for Hall thrusters will be designed. Additionally, an optimized passive two-phase TMS comprised of multiple heat pipes, cold and hot radiators will be integrated into a Hall thruster for demonstration testing in vacuum chambers. The performance of Hall thruster with advanced TMS will be assessed by measuring thrust, specific impulse, efficiency, oscillation in the discharge current and voltage etc. Upon successful demonstration of thermal performance and reliability testing, the final deliverable will be a flight-like Hall thruster integrated with passive two-phase TMS.
Benefits: The proposed passive two-phase thermal management system cooling system can effectively remove the waste heat from Hall thrusters to the heat sink. This will allow stability for a long-duration flight operation of high power-density Hall thruster in space. Many NASA programs will be benefited, including deep space Psyche, cis-lunar Gateway, electric propulsion to Mars and Planetary habitat, etc. High power-density Hall thrusters will be a game-changer in the future spaceflight market. The “plug-and-play” components developed under this program, are adaptable for many commercial Hall thrusters serving in telecommunication and defense applications. SpaceX, Busek, Aerojet Rocketdyne, etc. will be potential customers of this ACT’s passive two-phase thermal management technology.