The invention relates to the field of regulation of fluid flow rates, and in particular to a flow-rate-regulating device (109) comprising: an upstream chamber (206); a downstream chamber (207); a plurality of electrically conductive capillary ducts (201-205) fluidically connecting the upstream chamber (206) and the downstream chamber (207) in parallel; first and second electrical terminals (208, 209) able to be connected to an electrical current source; and at least one electrical switch (210a, 210b, 211a, 211b) placed so as to selectively connect one or more of said capillary ducts (201-205) between the electrical terminals (208, 209). The invention furthermore relates to a system for supplying propellant gas to a spatial electric thruster (101), comprising at least one such flow-rate-regulating device (109) for regulating a propellant gas flow rate, and to a method for regulating flow rate using such a flow-rate-regulating device (109).