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| Title: | Dormant cathode plasma properties in a multiple-cathode, high-power, rectangular discharge chamber |
| Author (s): | Rovey, Joshua L. Gallimore, Alec D. |
| Department/Lab Affiliations: | Mechanical & Aerospace Engineering Space Systems Engineering |
| Keywords: | Cathode Plasma Discharge Chamber diagnostic cylinders electron temperatures graphite erosion life-limiting phenomenon propulsion devices retarding potential analyzer (RPA) thruster |
| Issue Date: | 2005 |
| Publisher: | American Institute of Aeronautics and Astronautics |
| Citation: | Rovey, Joshua L., and Gallimore, Alec D. "Dormant Cathode Plasma Properties in a Multiple-Cathode, High-Power, Rectangular Discharge Chamber." AIAA-2005-4241, 41st Joint Propulsion Conference, 2005. |
| Abstract: | A high-power, rectangular discharge chamber is being investigated by the University of Michigan for operation with multiple discharge cathode assemblies (DCAs). The multiple cathode approach attempts to increase thruster lifetime by operating three DCAs sequentially, possibly providing a threefold increase in discharge life. Previous multiplecathode electric propulsion devices, such as the SPT-100, have shown dormant cathode erosion to be a life-limiting phenomenon. Similar results in a multiple-cathode discharge chamber (MCDC) may decrease the anticipated discharge lifetime. For the experiments presented here a MCDC test article (TA) is operated in the University of Michigan Large Vacuum Test Facility. In order to assess potential dormant cathode erosion, diagnostic cylinders (DCs) are designed and utilized to measure plasma properties at the dormant cathode locations. Each DC appears similar to the active DCA, but is outfitted with plasma diagnostics, such as Langmuir probes and a retarding potential analyzer (RPA). Langmuir probe results indicate that typical dormant cathode number densities, electron temperatures, and plasma potentials are 5.0x1011 cm-3, 5 eV, and 27 V, respectively. Most probable ion energy measurement results are consistent with the plasma potential measurements. Pre-operation erosion rates for molybdenum (Mo) and graphite dormant cathode keepers are estimated based on sputter threshold, yield, ion incidence angle, and ion flux equations. Results suggest little to no graphite erosion and a Mo erosion rate between 0- 40 mm/khr. |
| Type: | Article - Conference proceedings text |
| Copyright Notice: | This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. FULL COPYRIGHT INFORMATION: |
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| title | Dormant cathode plasma properties in a multiple-cathode, high-power, rectangular discharge chamber |
| contributor.author | Rovey, Joshua L. |
| contributor.author | Gallimore, Alec D. |
| contributor.deptlab | Mechanical & Aerospace Engineering |
| contributor.deptlab | Space Systems Engineering |
| contributor.sponsor | Glenn Research Center |
| subject | Cathode Plasma |
| subject | Discharge Chamber |
| subject | diagnostic cylinders |
| subject | electron temperatures |
| subject | graphite erosion |
| subject | life-limiting phenomenon |
| subject | propulsion devices |
| subject | retarding potential analyzer (RPA) |
| subject | thruster |
| date.issued | 2005 |
| publisher | American Institute of Aeronautics and Astronautics |
| identifier.citation | Rovey, Joshua L., and Gallimore, Alec D. "Dormant Cathode Plasma Properties in a Multiple-Cathode, High-Power, Rectangular Discharge Chamber." AIAA-2005-4241, 41st Joint Propulsion Conference, 2005. |
| identifier.pub.URI | |
| description.abstract | A high-power, rectangular discharge chamber is being investigated by the University of Michigan for operation with multiple discharge cathode assemblies (DCAs). The multiple cathode approach attempts to increase thruster lifetime by operating three DCAs sequentially, possibly providing a threefold increase in discharge life. Previous multiplecathode electric propulsion devices, such as the SPT-100, have shown dormant cathode erosion to be a life-limiting phenomenon. Similar results in a multiple-cathode discharge chamber (MCDC) may decrease the anticipated discharge lifetime. For the experiments presented here a MCDC test article (TA) is operated in the University of Michigan Large Vacuum Test Facility. In order to assess potential dormant cathode erosion, diagnostic cylinders (DCs) are designed and utilized to measure plasma properties at the dormant cathode locations. Each DC appears similar to the active DCA, but is outfitted with plasma diagnostics, such as Langmuir probes and a retarding potential analyzer (RPA). Langmuir probe results indicate that typical dormant cathode number densities, electron temperatures, and plasma potentials are 5.0x1011 cm-3, 5 eV, and 27 V, respectively. Most probable ion energy measurement results are consistent with the plasma potential measurements. Pre-operation erosion rates for molybdenum (Mo) and graphite dormant cathode keepers are estimated based on sputter threshold, yield, ion incidence angle, and ion flux equations. Results suggest little to no graphite erosion and a Mo erosion rate between 0- 40 mm/khr. |
| type | Article - Conference proceedings |
| type.DCMIType | text |
| rights | This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. |
| rights.URI | |
| date.accessioned | 2008-05-19T20:02:42Z |
| date.available | 2008-05-30T18:30:56Z |
| identifier.persist.URI |