Recent advances on electrically controlled solid propellants

The utilization of electrically controlled solid propellants (ECSPs) in rocket propulsion offers a viable solution to address the limitations posed by the thrust adjustment and restart capabilities in traditional solid rockets. The ECSP technology enables control of the rocket motor start-stop and propellant burning rate by regulating the power supply, resulting in enhanced flexibility and responsiveness in propulsion systems. Despite advancements in the formulation and charge design, combustion performance, and motor optimization for ECSPs, their high ignition voltage and narrow regulation range of thrust remain significant challenges for electrically controlled solid rockets. Designing an efficient formulation to tune the propellant's burning rate, energy density, and mechanical properties for specific requirements across various propulsion systems is a complex task. This challenge is particularly critical as the design must balance energy performance with the operational reliability of ECSPs. This review comprehensively summarizes the recent advances in this research field. The fundamental properties of ECSPs such as energy density, conductivity, combustion behavior, safety, mechanical properties, and processability are systematically compared and discussed. Additionally, the design and experimental results of electrically controlled solid rocket motors with various electrode configurations are summarized, addressing issues like ignition delays and limited thrust modulation. On this basis, the key challenges for future researches are underlined along with possible solutions.