Controlled chemi-ionization in space-formation and spectroscopy of metal oxide space clouds
Abstract
Communication with orbiting satellites and space vehicles is subject to interference resulting from the fluctuating electron densities encountered in the upper atmosphere. These uncontrolled signal modifications are also detrimental to targeting and GPS systems. It has been proposed that deliberate modification of high-altitude electron densities can be used to achieve temporary control of radio wave and microwave propagation. The chemi-ionization reactions M + O = MO+ + e- with M = Sm or Nd are being evaluated for their ability to transiently increase the electron density via controlled, high-altitude release of the atomic metal vapors. Sounding rocket experiments have been conducted using both Sm and Nd (referred to as metal oxide space cloud (MOSC) measurements). When the rocket reached the target altitude, the atomic Sm or Nd vapor was released by means of a thermite reaction. The atomic vapor subsequently reacted with the ambient atomic oxygen. The MOSC experiments were conducted under conditions where the cloud was subject to excitation by solar radiation. This resulted in visible-range fluorescence that was described as being pink for Sm, and green for Nd. Spectroscopic data were recorded for the Sm-release, and emission bands occurring in the red spectral range have been reliably assigned to neutral SmO. The degree of ionization achieved in the Sm experiments was below the expected result, and the question of whether SmO+ was present could not be resolved. The only spectroscopic data available for the Nd-release was the color of the MOSC emission. Interpretations of the data obtained in the MOSC experiments have been limited to informed speculation due to the lack of definitive spectroscopic data for the monoxides and their singly charged cations. In the proposed program we will record electronic spectra for SmO, SmO+, NdO, and NdO+. These measurements will include determinations of radiative transition probabilities and photoionization cross-sections. The primary goal of this effort will be to obtain the essential laboratory data needed for the analyses of the MOSC field experiments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 06, 2024
- Source ID
- FA95502310321
Entities
People
- Michael C Heaven
Organizations
- Air Force Office of Scientific Research
- Emory University
- United States Air Force