On Command Pyrotechnic Light, Color, and Temperature Enhancement through Microwave Irradiation

Abstract

This work demonstrates the dynamic control of light emission from a magnesium / polytetrafluoroethylene (Mg/PTFE) pyrotechnic through microwave irradiation (2.46 GHz, 1 kW CW). Pyrotechnic combustion experiments were conducted within a multimodal microwave cavity and were instrumented with UV-VIS spectroscopy, color video, and two-color high-speed video pyrometry. Microwave irradiation was found to increase UV-VIS light emission of a typical combustion event by 120 . Increases in the flame volume are also observed. This emission enhancement primarily occurs between ~350 to 400 nm and is due to microwave absorption by the transition enhancement of the diatomic species MgO and MgF. In contrast to prior studies on microwave irradiation of Mg/alkali nitrate flames, significant enhancement of continuum emission is also observed from Mg/PTFE as a result of temperature enhancement of the condensed phase flame species. To a lesser extent, atomic species emission is observed to increase due to electronic transition enhancement. Moreover, chromaticity of Mg/PTFE combustion show that a shift in color is possible utilizing microwave energy, due to enhancement of molecular and atomic emission. Temperature measurements using both two-color video pyrometry and gray body fitting consistently show microwave irradiation results in temperature increases of ~100-300 K. Energy deposition to the Mg/PTFE system is hypothesized to primarily occur from dielectric and eddy current loss to condensed phase species within the flame (magnesium fluorides and carbon), and temperature enhancement is limited by volatilization of these species. This work demonstrates the ability to tune Mg/PTFE pyrotechnic light emission output, more specifically enabling dynamic, on-command control of the light emission color and intensity.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Jul 11, 2022
Accession Number
AD1191858

Entities

People

  • James Bret Michael
  • Jonathan M. Dilger
  • Ryan Ogorzalek
  • Stuart J. Barkley
  • Travis R. Sippel
  • William F Crespo-miranda

Organizations

  • Iowa State University
  • Naval Surface Warfare Center

Tags

Communities of Interest

  • Advanced Electronics
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Burning Rate
  • Chemistry
  • Combustion
  • Combustion Products
  • Electric Fields
  • Electromagnetic Fields
  • Emission Spectra
  • Energetic Materials
  • Energy Transfer
  • Fluoropolymers
  • Ignition
  • Materials
  • Materials Processing
  • Materials Science
  • Measurement
  • Propellants
  • Solid Propellants
  • Spectra
  • Spectroscopy
  • Visible Spectra

Fields of Study

  • Physics

Readers

  • Materials Science and Engineering.
  • Rocket Propulsion.
  • Spectroscopy.

Technology Areas

  • Microelectronics