Electric thruster, a method of stopping an electric engine included in such a thruster, and a satellite including such a thruster
View Patent ↗An electric thruster includes at least one electric engine, a feed system for the engine including a high-pressure tank of ionizable gas, a low-pressure buffer tank connected to the high-pressure tank by a valve, and a system of pipes for conveying the gas from the low-pressure buffer tank to an anode and to a cathode of the engine. The low-pressure buffer tank is in open connection with the engine. The thruster detects that a magnitude of the discharge current between the anode and the cathode is less than a threshold value and switches off the discharge voltage as a result of the detection. The thruster can be for use in a satellite.
1. An electric thruster comprising:
at least one electric engine including an anode, a cathode, and a gas manifold;
a feed system for the engine, the feed system comprising:
a high-pressure tank of ionizable gas;
a low-pressure buffer tank connected to the high-pressure tank by a means for dropping a pressure of the gas;
at least one valve configured to open, close, or regulate a flow rate of gas between the high-pressure tank and the low-pressure buffer tank; and
a system of pipes for conveying the gas from the low-pressure buffer tank to the gas manifold of the engine; and
power electronics configured to deliver or not deliver electric power to the engine by applying or interrupting a discharge voltage between the anode and the cathode;
wherein the low-pressure buffer tank is in open connection with the gas manifold and with the anode and with the cathode; and
further comprising means for detecting that a magnitude of the discharge current between the anode and the cathode is less than a threshold value and for interrupting the discharge voltage as a result of making the detection.
2. An electric thruster according to claim 1 , wherein the threshold value is about 1 mA for an engine when a nominal value of the magnitude of the discharge current is about 1 A.
3. An electric thruster according to claim 1 , further comprising a restrictor between the high-pressure tank and the low-pressure buffer tank, and wherein the low-pressure buffer tank has a capacity of less than 20 cm 3 .
4. An electric thruster according to claim 1 , further comprising a regulator member between the high-pressure tank and the low-pressure buffer tank, together with means for controlling the regulator member so as to obtain at an outlet from the low-pressure buffer tank a pressure that varies in amplitude by less than 5% around a setpoint pressure.
5. An electric thruster according to claim 4 , wherein a mean value of the pressure is in a range of 0.1 bars to 10 bars.
6. A satellite comprising an electric thruster according to claim 1 .
7. A method of controlling an electric engine including an anode, a cathode, and a gas manifold, the engine being included in an electric thruster that includes:
a feed system for the engine, the feed system including:
a high-pressure tank of ionizable gas;
a low-pressure buffer tank connected to the high-pressure tank by means for dropping a pressure of the gas, and in open connection with the engine;
at least one valve configured to open, close, or regulate a flow rate of gas between the high-pressure tank and the low-pressure buffer tank; and
a system of pipes for conveying the gas from the low-pressure buffer tank to the gas manifold; and
power electronics configured to deliver or not deliver electric power to the engine by applying or interrupting a discharge voltage between the anode and the cathode;
the method comprising, with the low-pressure buffer tank being in open connection with the anode and with the cathode:
closing the valve to interrupt the flow of gas between the high-pressure tank and the low-pressure buffer tank;
detecting a magnitude of the discharge current between the anode and the cathode that is lower than a threshold value; and
switching off the discharge voltage as a result of making the detection.