Experimental study of ion beam interaction with target surface aimed at developing a contactless method for space debris removal by an ion beam.

Research and development in the field of space debris (SD) removal technologies is one of the most important and urgent tasks facing all spacefaring nations. By now, a large number of different concepts of removal have already been proposed. One of them is the SD removal by ion beam generated by an ion source installed on board a service spacecraft (SSC). A detailed understanding of the process of ion beam interaction with the SD surface is required to develop an optimal control algorithm for the virtual SSC-SD mated configuration in order to improve this method of SD removal. In addition, when designing the SSC, it is necessary to take into account back flows of the material sputtered from the surface of removed SD by the ion beam, which can contaminate the SSC operating surfaces during the removal maneuver. Within the framework of the presented work, experimental studies were performed to determine the coefficient of accommodation of the ion impulse during the ion beam interaction with the surface of the target simulating the external surface of the removed object. Besides, the flow density of the sputtered target material was experimentally evaluated during its exposure to the ion beam. To do this, we used the radio-frequency ion source (injector) with a beam diameter of 160 mm, which is supposed to be used as an actuating unit on board the SSC designed for transporting the SD objects to the disposal orbit or to the orbits with limited life. When measuring the ion beam accommodation coefficient, the presence of additional force arising on the target due to the flow of sputtered material leaving its surface, and the ion-electron emission process on the target, which could distort the experimental data, were taken into account. To estimate the magnitude of the flows of sputtered target material under the influence of the ion beam, a special experimental design was developed for simulating the presence of a point source of sputtered material. The results obtained in this work will be used for modeling the impact of the ion beam on the surface of real SD objects with complex geometry using the finite element method, for refining the control algorithm of the virtual SSC-SDO mated configuration and for developing proposals on the SSC layout, which should reduce or completely eliminate the negative impact associated with the material sputtering from the SDO surface onto the SSC elements. Successful implementation of the developed method of SDO removal will contribute to improving the safety of space activities for all countries and to the development of the rocket-and-space industry in the Russian Federation, in particular. • The accommodation coefficient of the ion beam momentum was determined. • The back flow of sputtered target particles was estimated. • In a first approximation, the form of the target material sputtering indicatrix was obtained. [ABSTRACT FROM AUTHOR]