RF Test Cell Canonical Focus Experiments- Ionization, Dissociation, and Recombination for Molecular Propellants- Nitrogen and Hydrogen
Abstract
First principles design of electric space propulsion devices utilizing molecular propellants requires understanding the fundamental processes required to transform molecules into ions. This understanding of RF ionization from neutral to fully ionized plasma is currently only empirical. It is necessary to develop computational models to aid design of thruster technology, predict plasma state, and evaluate thruster performance and lifetime. In order to develop computational models capable of modeling the RF thruster plasma state and predicting lifetime and performance operating on molecular propellants, an understanding of the critical mechanisms for excitation, ionization, dissociation, recombination, and relaxation in the molecules of interest must be advanced. We propose to develop an experimental platform to study excitation, ionization, and dissociation in N2 and H2 molecules in a 50-W inductively coupled RF discharge operating at 10 Torr and 1.0 SLM. These molecules were chosen because of the vast knowledge of their spectroscopic properties and their presence in molecular propellants of interest. Using coherent anti-Stokes Raman scattering (CARS), saturated absorption spectroscopy, laser-induced fluorescence (LIF) spectroscopy, Thomson scattering, and optical emission spectroscopy (OES), will measure translational, excitation, vibrational, rotational and electron temperatures, and ionization and dissociation fractions. Physical probes will be used to measure plasma potential, number density, and electron temperature. Electric fields produced by the RF antenna will be modeled using COMSOL Multiphysics software. Propellant will be injected into the test cell where we will vary the field strength and frequency to determine how electric field shape and magnitude affect dissociation and ionization in diatomic molecules. The goal of the proposed research is to begin to build the knowledge base for molecular ionization in RF plasma that exists for atomic propellants.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410319
Entities
People
- Kristina Lemmer
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- Western Michigan University