Perspectives on Physics of E×B Discharges Relevant to Plasma Propulsion and Similar Technologies

This paper provides perspectives on recent progress in understanding the physics of devices in which the external magnetic field is applied perpendicular to the discharge current. This configuration generates a strong electric field that acts to accelerate ions. The many applications of this set up include generation of thrust for spacecraft propulsion and separation of species in plasma mass separation devices. These "“E X B” plasmas are subject to plasma–wall interaction effects and to various micro- and macroinstabilities. In many devices we also observe the emergence of anomalous transport. This perspective presents the current understanding of the physics of these phenomena and state-ofthe-art computational results, identifies critical questions, and suggests directions for future research.Y. Raitses and I. D. Kaganovich gratefully acknowledge partial financial support by the AFOSR grant (No. FA9550–17-1–0010) and assistance in preparation and fruitful discussions with I. Romadanov, Eduardo Rodriquez, and J. B. Simmonds. The work of A. Smolyakov was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC) Canada, by the AFOSR grant (No. FA9550-18-1-0132), and by Compute Canada, and he acknowledges fruitful discussions with O. Chapurin, S. Janhunen, M. Jimenez, O. Koshkarov, I. Romadanov, and D. Sydorenko. The contribution of E. Ahedo and M. Merino was supported by the Government of Spain, National Development and Research Program, Grant No. PID2019-108034RB-I00, and they thank J. Navarro and P. Fajardo for their contribution. M. Keidar and I. Schweigert gratefully acknowledge the AFSOR grant (No. FA9550-19-1-0166). I. Schweigert was partly supported by the Russian Science Foundation (Grant No. 17-19-01375). S. Tsikata acknowledges support from CNES (Centre national d’ etudes spatiales, France). F. Taccogna gratefully acknowledges financial support from the Italian minister of university and research (MIUR) under the project PON “CLOSE to the Earth” No. ARS ARS01–00141. R. Gueroult and N. J. Fisch were supported by Nos. DOE DESC0016072 and NSF PHY-1805316. A. Bourdon and P. Chabert gratefully acknowledge financial support of the French National Research Agency (L’Agence nationale de la recherche) ANR grant (No. ANR-16-CHIN-003-01) and Safran Aircraft Engines within the project POSEIDON Israel Science Foundation, Grant 1581/16