Physical Principles and Main Research Results Determining the Development of Thrusters with Closed Electron Drift

The paper presents the results of many years of research carried out in various organizations of the USSR and Russia in the process of developing thrusters with anode layer (TALs) and stationary plasma thrusters (SPTs). They are known under the general name “thrusters with closed electron drift” (TCEDs), since they are developed on the basis of plasma ion accelerators with closed electron drift (ACEDs). TCEDs have come a long way in development. As a result, the SPT has become one of the most widely used electric rocket thrusters (ERTs) and continues to develop. The TAL development has also reached a fairly high level and is close to practical use. Therefore, here we consider the main physical principles and research results that determined the progress in the SPT and TAL development with the aim of their analysis and generalization, as well as assessment of their applicability for further development such thrusters. A brief overview of the main stages of the SPT and TAL development and the results achieved at these stages are given. It is shown that the main problem of their further development is to ensure both high thrust efficiency and a long service life. It is also shown that the main factor limiting the service life of TALs and SPTs is the ingress of accelerated ions onto their structure elements; therefore, in order to control the ion motion, it is first of all necessary to understand the patterns of electric field formation in TCED discharges. New properties of TCED discharges and the peculiarities of electric field formation are revealed and their known properties are clarified, which determine the thickness and position of the acceleration zone with the main potential drop in the discharge and the flows of accelerated ions onto the thruster structure elements. The methods of controlling the thickness and position of the acceleration zone in an TCED by varying the magnetic field characteristics, successfully tested at the second stage of the SPT and TAL development, are considered and analyzed. It is shown that these methods make it possible to effectively control the operation of an TCED and its characteristics, and physical conditions ensuring the efficiency of their application are determined. Physical conditions for the implementation and justification of the feasibility of completely removing the acceleration zone from the thruster as the main direction of modern TCED development are determined, taking into account the analysis of the properties of the discharge and the peculiarities of electric field formation in an TCED. The main conclusions on the issues considered are given.