In-Space Propulsion High Voltage Hall Accelerator Development Project Overview

Abstract

NASA's Science Mission Directorate In-Space Propulsion Technology Project is funding the development of a high specific impulse long life Hall thruster. The goal of the high voltage Hall accelerator (HiVHAc) project is to develop a flight-like, engineering model (EM) Hall thruster that can meet future NASA science mission requirements. These requirements are met by a thruster that operates over an input power range from 0.3 to 3.5 kW, attains specific impulses from 1,000 to 2,700 seconds, and processes at least 300 kg of xenon propellant at full power. To demonstrate the HiVHAc project goal, two laboratory thrusters have been built and tested. The latest laboratory thruster, the NASA-103M.XL, incorporated a life-extending discharge channel replacement innovation and has been operated for approximately 5,000 hours at a discharge voltage of 700 volts. In 2007, NASA Glenn Research Center teamed with Aerojet to design and manufacture a flight-like HiVHAc EM thruster which incorporated this life-extending channel replacement innovation. The EM thruster was designed to withstand the structural and thermal loads encountered during NASA science missions and to attain performance and lifetime levels consistent with NASA missions. Aerojet and NASA Glenn Research Center have completed the EM thruster design, structural and thermal analysis, fabrication of thruster components, and have assembled and extensively tested one EMl thruster. Performance and thermal characterization of the engineering model thruster has been performed for discharge power levels up to 3.5 kW. The results indicate discharge efficiencies up to of 63% and discharge specific impulse up to 2,930 seconds. In addition to the thruster development, the HiVHAc project is leveraging power processing unit and xenon flow system developments sponsored by other projects but that can apply directly to a HiVHAc system. The goal is to advance the technology readiness level of a HiVHAc propulsion system to 6.

Farfield Ion Current Density Measurements before and after the NASA HiVHAc EDU2 Vibration Test

“…The reason for this is expressed in the integrals in Eq. (1) and (2). The area element associated with ion current measured at the center is much smaller than the area element associated with off-center data.…”

“…The total ion current can be calculated using the denominator in Eq. (1) or (2). The total ion current can then be used to calculate the current utilization efficiency.…”

“…The EDU2 has undergone the performance acceptance test (PAT) and the vibration test. 2 To check that the vibration test did not negatively impact the operation of the thruster, thrust and ion current density measurements were taken before and after the vibration test. The performance characterization of the EDU2 is concurrently published in a separate paper.…”

Status of Sample Return Propulsion technology development under NASA's ISPT program

“…There are mission studies that indicate that BPT-4000 is directly applicable to ERV and Discovery-class missions. For more HIVHAC information, see References [8,9].…”

Sample return propulsion technology development under NASA's ISPT project

“…Preliminary performance mapping of the EM thruster at various operating conditions was performed at NASA Glenn Research Center (GRC). [2] In the future, the test sequence will include performance acceptance tests, environmental tests and a long duration test in FY11 and FY12. Current plans include the design, fabrication and assembly of a full Hall propulsion system, but are pending final approval to proceed.…”