# US 12,006,922 B1 · Precision manifold for an ion thruster using characterized flow restrictors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,006,922 B1 - Document ID: US12006922B1 - Status: Granted - Kind: B1 - Application number: 16/799,079 - Filed: 2020-02-24 - Granted: 2024-06-11 - Earliest claimed: 2019-02-25 - Assignees: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration - Applicants: United States of America as represented by the Administrator of NASA - Inventors: Timothy G. Gray; Gabriel F. Benavides - Web page: https://patentgrep.com/patent/US12006922B1 ## CPC - F03H 1/0012: {Means for supplying the propellant} - B64G 1/413: {Ion or plasma engines} - F03H 1/0075: {with an annular channel; Hall-effect thrusters with closed electron drift} - F03H: PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR (from combustion products F02K) - B64G: COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR ## Abstract Precision flow restrictors and techniques for manufacturing the same for ion thruster manifolds are disclosed. Flow restricting features are moved out of the manifold base and into separate flow restrictors, allowing a wider range of manufacturing techniques and materials to be applied. Quality control can be performed at the level of the flow restrictors as subcomponents, ensuring that only good parts with ideal flow characteristics make it into the final assembly and improving the yield rate of the final manifold assembly. ## Claims ### Claim 1 An apparatus, comprising: a plurality of flow restricting elements configured to restrict a flow of a propellant; and a manifold base comprising a plurality of holes, each flow restricting element of the plurality of flow restricting elements located in a respective hole of the plurality of holes, wherein the plurality of flow restricting elements are separate subcomponents from the manifold base; and a propellant delivery tube comprising an end that enters the manifold base and is configured to deliver the propellant thereto, wherein a gas-dynamic flow restriction characteristic of each flow restricting element of the plurality of flow restricting elements is based on a proximity of the respective flow restricting element of the plurality of flow restricting elements to the end. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the gas-dynamic flow restriction characteristic of each flow restricting element the plurality of flow restricting elements is decreased depending on a respective distance from the end to accommodate for a pressure drop in the propellant at the respective flow restricting element of the plurality of flow restricting elements. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein each flow restricting element of the plurality of flow restricting elements are is configured to provide the same uniform propellant flow rate regardless of the respective distance from the end. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising: a manifold cover that forms a plenum with the manifold base, the plenum configured to distribute the flow of propellant to the plurality of flow restricting elements; and a plurality of respective exit channels for each flow restricting element of the plurality of flow restricting elements, each of the plurality of respective exit channels configured to channel a respective flow of the propellant out of the apparatus. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising: at least one carrier for at least one flow restricting element of the plurality of flow restricting elements, the at least one carrier configured to secure the at least one flow flow restricting element of the plurality of flow restricting elements in the respective hole of the manifold base. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the at least one carrier and the at least one flow restricting element comprise a different material. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the at least one carrier comprises corundum or a ceramic. ### Claim 8 (depends on 5) The apparatus of claim 5, wherein the at least one carrier and the manifold base comprise a same material. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein at least one flow restricting element of the plurality of flow restricting elements comprises a single orifice. ### Claim 10 (depends on 9) The apparatus of claim 9, wherein the single orifice comprises a converging section. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein at least one flow restricting element of the plurality of flow restricting elements comprises a sintered porous material. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein at least one flow restricting element of the plurality of flow restricting elements comprises a plurality of orifices. ### Claim 13 A manifold assembly for an ion thruster, comprising: a plurality of flow restricting elements configured to restrict a flow of a propellant; a manifold base comprising a plurality of holes, each flow restricting element of the plurality of flow restricting elements located in a respective hole of the plurality of holes; and a propellant delivery tube comprising an end that enters the manifold base and is configured to deliver the propellant thereto, wherein the plurality of flow restricting elements are separate subcomponents from the manifold base, and a gas-dynamic flow restriction characteristic of each flow restricting element of the plurality of flow restricting elements is based on a proximity of the respective flow restricting element of the plurality of flow restricting elements to the end. ### Claim 14 (depends on 13) The manifold assembly of claim 13, wherein wherein the gas-dynamic flow restriction characteristic of each flow restricting element the plurality of flow restricting elements is decreased depending on a respective distance from the end to accommodate for a pressure drop in the propellant at the respective flow restricting element of the plurality of flow restricting elements, and each flow restricting element of the plurality of flow restricting elements is configured to provide the same uniform propellant flow rate regardless of the respective distance from the end. ### Claim 15 (depends on 13) The manifold assembly of claim 13, further comprising: at least one carrier for at least one flow restricting element of the plurality of flow restricting elements, the at least one carrier configured to secure the at least one flow flow restricting element of the plurality of flow restricting elements in the respective hole of the manifold base, wherein the at least one carrier and the at least one flow restricting element comprise a different material.