Is the gas-fed PPT an electromagnetic accelerator? An investigation using measured performance

J. K. Ziemert, Edgar Yazid Choueiri, Daniel Birx

Research output: Contribution to conferencePaper

9 Scopus citations

Abstract

We present a new gas-fed pulsed plasma thruster performance database and use it to investigate the electromagnetic nature of the acceleration process by-identifying trends in the dependencies of the perfor-mance parameters on the mass bit, energy, and ca-pacitance. It was previously observed[l] that perfor-mance measurements for PPTs operating at low mass bits (< 2 μg per pulse) can be influenced by contami-nation from diffusion pump oil. Consequently, facility renovations and a new impulse measurement protocol using liquid nitrogen cooled baffles to reduce diffusion pump oil backstreaming were implemented and are discussed. A portion of the database has been dupli-cated in a cryo-pumped facility at NASA-JPL to verify that the contamination effects have been removed. The intermittent simultaneous operation of the discharge initiation plugs, that was previously observed to degrade the performance, was solved with a new electric circuit and the resulting discharge symmetry verified using a fast-framing camera. The nature of the acceleration process is examined by comparing trends in the performance database with the theoret-ically expected scaling for electromagnetic accelera-tion. The performance was found to transition with decreasing mass bit (or increasing Isp) from a mode (Mode I) where the efficiency and the impulse are respectively independent and dependent on the mass bit (and where the efficiency the thrust to power ratio are respectively independent and dependent on Isp) to another mode (Mode II) where the converse statements hold. Furthermore, in mode II the efficiency is independent of energy level and both the efficiency and the thrust-to-power ratio scale with the square root of capacitance as expected in a predominantly electromagnetic accelerator.

Original languageEnglish (US)
StatePublished - Jan 1 1999
Event35th Joint Propulsion Conference and Exhibit, 1999 - Los Angeles, United States
Duration: Jun 20 1999Jun 24 1999

Other

Other35th Joint Propulsion Conference and Exhibit, 1999
CountryUnited States
CityLos Angeles
Period6/20/996/24/99

All Science Journal Classification (ASJC) codes

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Control and Systems Engineering
  • Aerospace Engineering

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    Ziemert, J. K., Choueiri, E. Y., & Birx, D. (1999). Is the gas-fed PPT an electromagnetic accelerator? An investigation using measured performance. Paper presented at 35th Joint Propulsion Conference and Exhibit, 1999, Los Angeles, United States.