Bi-modal chemical-electric space propulsion
Bi-modal propulsion systems and related methods are generally described. In some embodiments, a bi-modal propulsion system may employ a single propellant for both chemical thruster(s), operating at elevated pressures, and electrical thruster(s) (e.g., electro spray thruster), operating at reduced pressures. The propellant pressure may be reduced to a desired operational range of the electrical thruster(s) using any appropriate construction including, for example, capillaries configured to reduce the pressure of the propellant to an operational range of the electrical thruster(s). In some embodiments, the reduced pressure of the propellant may be lower than a vapor pressure of at least one volatile component of the propellant, leading to the formation of “bubbles” within the propellant line. The presence of alternating gas and liquid phases along a flow path between a propellant tank and the electrical thruster(s) may help to electrically insulate the electrical thruster from the rest of the system.
1. A propulsion system comprising:
a tank configured to hold an ionic liquid at a first pressure;
at least one electrical thruster in selective fluid communication with the tank, wherein the first pressure is greater than an operational pressure range of the at least one electrical thruster;
at least one capillary positioned along a flow path between the tank and the at least one electrical thruster, the at least one capillary in fluid communication with the tank and the at least one electrical thruster; and
at least one conduit fluidly coupling the at least one capillary and the at least one electrical thruster, wherein the ionic liquid does not wet a material of the at least one conduit,
wherein the at least one capillary is configured to de-pressurize the ionic liquid from the first pressure to a second pressure less than the first pressure,
wherein the second pressure is below a vapor pressure of at least one volatile component of the ionic liquid, and
wherein the second pressure is within the operational pressure range of the at least one electrical thruster.
2. The propulsion system of claim 1 , wherein the second pressure is at least 0.1 times less than the first pressure.
3. The propulsion system of claim 1 , further comprising:
one or more valves positioned upstream of the at least one electrical thruster; and
one or more processors configured to control flow of the ionic liquid with the one or more valves.
4. The propulsion system of claim 1 , wherein the at least one electrical thruster is an electrospray thruster.
5. The propulsion system of claim 1 , wherein the ionic liquid is a monopropellant.
6. The propulsion system of claim 1 , wherein the tank is in selective fluid communication with at least one chemical thruster.
7. The propulsion system of claim 1 , wherein the at least one volatile component at least partially evaporates within the at least one conduit to form a gas phase, and wherein the gas phase electrically isolates the at least one electrical thruster from the tank.
8. A propulsion system comprising:
a tank configured to hold an ionic liquid, the ionic liquid comprising at least one volatile component;
at least one electrical thruster in selective fluid communication with the tank; and
at least one conduit positioned in between the tank and the at least one electrical thruster,
wherein an inlet pressure of the at least one conduit is below a vapor pressure of the at least one volatile component, wherein the at least one volatile component at least partially evaporates within the at least one conduit to form a gas phase, and wherein the gas phase electrically isolates the at least one electrical thruster from the tank.
9. The propulsion system of claim 8 , wherein the ionic liquid does not wet a material of the at least one conduit.
10. The propulsion system of claim 8 , further comprising at least one capillary positioned along a flow path between the tank and the at least one electrical thruster, wherein the at least one capillary is configured to de-pressurize the ionic liquid to an operational pressure range of the at least one electrical thruster.
11. The propulsion system of claim 8 , further comprising:
one or more valves positioned upstream of the at least one electrical thruster; and
one or more processors configured to control flow of the ionic liquid with the one or more valves.
12. The propulsion system of claim 8 , wherein the at least one electrical thruster is an electrospray thruster.
13. The propulsion system of claim 8 , wherein the ionic liquid is a monopropellant.
14. The propulsion system of claim 8 , wherein the tank is in selective fluid communication with at least one chemical thruster.
15. The propulsion system of claim 10 , wherein the at least one capillary is configured to de-pressurize the ionic liquid to an outlet pressure at least 0.1 times less than the inlet pressure.
16. A propulsion system comprising:
a tank configured to hold an ionic liquid at a first pressure;
at least one chemical thruster in selective fluid communication with the tank;
at least one electrical thruster in selective fluid communication with the tank, wherein the first pressure is greater than an operational pressure range of the at least one electrical thruster; and
at least one feed system disposed along a flow path between the at least one electrical thruster and the tank, wherein the at least one feed system is configured to de-pressurize the ionic liquid from the first pressure to a second pressure less than the first pressure, and wherein the second pressure is within the operational pressure range of the at least one electrical thruster, wherein the at least one feed system includes:
at least one capillary positioned along the flow path between the tank and the at least one electrical thruster, wherein the at least one capillary is configured to de-pressurize the ionic liquid from the first pressure to the second pressure; and
at least one conduit fluidly coupling the at least one capillary and the at least one electrical thruster, wherein an inlet pressure of the at least one conduit is below a vapor pressure of at least one volatile component of the ionic liquid, wherein the ionic liquid does not wet a material of the at least one conduit.
17. The propulsion system of claim 16 , wherein the second pressure is at least 0.1 times less than the first pressure.
18. The propulsion system of claim 16 , wherein the at least one electrical thruster is an electrospray thruster.
19. The propulsion system of claim 16 , wherein the ionic liquid is a monopropellant.
20. The propulsion system of claim 16 , further comprising:
one or more valves positioned upstream of the at least one electrical thruster; and
one or more processors configured to control flow of the ionic liquid with the one or more valves.