ELECTRIC THRUSTER WITH HEXABORIDE EMITTER
A system according to an example of the present disclosure includes an electric thruster configured to generate thrust. The electric thruster includes an electron emitter that comprises a thermionic emission material selected from the group consisting of multi-metal hexaborides. The multi-metal is Eu and a second metal selected from the group consisting of Rare Earth elements excluding Sc, Y, Pm, and Yb.
1 . A system comprising:
an electric thruster configured to generate thrust, the electric thruster including an electron emitter comprising a thermionic emission material selected from the group consisting of multi-metal hexaborides, the multi-metal is Eu and a second metal selected from the group consisting of Rare Earth elements excluding Sc, Y, Pm, and Yb.
2 . The system as recited in claim 1 , wherein the thermionic emission material has a Pilling Bedworth Ratio of greater than 2 and up to 5.
3 . The system as recited in claim 1 , wherein the second metal is selected from the group consisting of Ce, La, Nd, and combinations thereof.
4 . The system as recited in claim 1 , wherein the multi-metal includes, by atomic percentage of all of the multi-metals, at least 50% of Eu.
5 . The system as recited in claim 4 , wherein the multi-metal includes a remainder of Ce, Nd, La, or mixtures thereof.
6 . The system as recited in claim 4 , wherein the multi-metals include, by atomic percentage of all of the multi-metals, 7% to 10% of La.
7 . The system as recited in claim 4 , wherein the multi-metals include, by atomic percentage of all of the multi-metals, 1% to 8% of Ce, 1% to 8% of Nd, or 1% to 8% of Ce and Nd combined.
8 . The system as recited in claim 1 , wherein the multi-metals consist of Eu and one or more of Ce, Nd, or La.
9 . The system as recited in claim 1 , wherein the multi-metals include, by atomic percentage of all of the multi-metals, 7% to 10% of La.
10 . The system as recited in claim 1 , wherein the multi-metals include, by atomic percentage of all of the multi-metals, 1% to 8% of Ce, 1% to 8% of Nd, or 1% to 8% of Ce and Nd combined.
11 . The system as recited in claim 1 , further comprising a hollow cylindrical cathode tube, and the electron emitter is disposed in the hollow cylindrical cathode tube.
12 . The system as recited in claim 11 , wherein the electron emitter is cylindrical.
13 . The system as recited in claim 12 , further comprising an oxygen-containing propellant gas source fluidly connected with the hollow cylindrical cathode tube.
14 . A spacecraft including the system as recited in claim 1 .
15 . A system comprising:
an electric thruster configured to generate thrust, the electric thruster including an electron emitter comprising a thermionic emission material selected from the group consisting of multi-metal hexaborides.
16 . The system as recited in claim 15 , wherein the multi-metal includes Eu.
17 . The system as recited in claim 16 , wherein the multi-metal includes a second metal selected from the group consisting of Rare Earth elements excluding Sc, Y, Pm, and Yb.