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MA DYNAMICS

MHD Thruster with Capillary-Porous Electrodes V. I. Ilgisonisa, b and Yu. V. Martynenkoc, d, * a

b

State Atomic Energy Corporation “Rosatom,” Moscow, 119017 Russia Peoples’ Friendship University of Russia (RUDN University), Moscow, 117198 Russia c National Research Center “Kurchatov Institute,” Moscow, 123182 Russia d National Research Nuclear University “MEPhI,” Moscow, 115409 Russia *e-mail: [email protected] Received April 20, 2018; revised May 31, 2018; accepted May 31, 2018

Abstract—Capillary-porous electrodes for plasma MHD devices are considered. The electrodes can be continuously renewable and allow one to use a scheme of the inverted MHD generator (i.e., MHD accelerator) as a thruster for interorbital flights. Two types of plasma acceleration are considered: (i) Lorentz force acceleration with a primary current perpendicular to the acceleration direction (Faraday scheme) and (ii) acceleration based on the Hall effect. In the first case, the thruster has advantages only at thrust powers exceeding 1 MW, while in the second case, the thrust and specific impulse are comparable with those of the known analogs (or even surpass them) already at powers of 500–1000 kW. The operating conditions of capillary-porous electrodes are formulated. DOI: 10.1134/S1063780X19010069

1. INTRODUCTION At present, works are being under way to create an efficient thruster for interorbital flights [1]. For these thrusters, nuclear power systems with a power of up to 15 MW are being developed [2]. An important characteristic of an interorbital thruster is its durability. Recently [3], capillary-porous electrodes have been proposed to be used for plasma MHD devices. The plasma-facing side of the capillary-porous electrode is composed of porous mats impregnated with liquid metal incoming due to surface tension from a vessel filled with melt metal. Such electrodes can be renewable, and their service life is limited only by the amount of the stored metal. If there are no erosion and degradation of the electrodes, then a simple scheme of the inverted MHD generator (i.e., MHD accelerator) can be used as a thruster. The accelerator is a rectilinear chamber, in which the magnetic field B is directed along the y axis and the current flows along the z axis between the capillary-porous electrodes. The capillary-porous electrodes should be sectioned, i.e., divided into bands perpendicular to the х axis. This is necessary (as in MHD generators) to suppress the Hall currents within the electrodes. For the thruster under study, it can be offered that the electrodes with a length of  = 10 cm (along the у axis) and width of 1 cm (along the х axis) be separated with insulators 1 cm wide along the х axis. The magnetic field can be created by permanent magnets, which presently can ensure a field strength of up to 1.5 T. The j × B force accelerates the plasma along the х axis. In the first

scheme, the current along the z axis is generated when a voltage is applied across opposite electrodes (Fig. 1). In the second scheme with Hall accel