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Plume divergence characterization for electric propulsion via standard deviation and emittance
McKenna J D Breddan1, Richard E Wirz1
1Mechanical and Aerospace Engineering, University of California, los Angeles, 420 Portola Plaza, Los Angeles, 90095 CA USA.
Journal of Electric Propulsion
|February 28, 2025
Summary
New methods using standard deviation and emittance offer quantitative insights into electric propulsion system plumes. These approaches improve understanding of plume divergence and evolution, overcoming limitations of existing descriptive techniques.
Area of Science:
- Spacecraft propulsion
- Plasma physics
- Aerospace engineering
Background:
- Electric propulsion systems are crucial for spacecraft, but their plume behavior is complex.
- Current methods for analyzing plume divergence lack quantitative accuracy and are affected by outlier particles.
Purpose of the Study:
- To introduce novel, quantitative methods for describing electric propulsion plume divergence and evolution.
- To provide reliable insights into the collective behavior of plume species.
Main Methods:
- Utilizing standard deviation to characterize plume divergence.
- Applying the emittance metric, adapted from particle accelerators, to analyze plume evolution in position-angle space.
- Performing cross-sectional emittance measurements to detect non-Hamiltonian forces like Coulomb collisions.
Main Results:
- Standard deviation and emittance provide quantitative measures of plume divergence and collective species behavior.
- Emittance diagrams accurately describe plume evolution in 2D position-momentum angle space.
- Cross-sectional emittance reveals the influence of stochastic Coulomb collisions on plume dynamics.
Conclusions:
- Emittance is a powerful tool for understanding electric propulsion plume evolution and identifying non-Hamiltonian effects.
- Full-plume emittance diagrams can determine when a plume has reached a steady state, crucial for mission planning.
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