Decomposition of Carbon Dioxide in a Capacitively Coupled Radio Frequency Discharge

<p>Decomposition of CO₂ was studied in a capacitively coupled radio frequency discharge using Martian Simulant Gas mixture that contains 95% CO₂. The discharge was operated at a gas pressure of 3 to 6 Torr and a discharge power density of less than 2.0 W/cm³. The main mechanism of the CO₂ decomposition process is the electron impact dissociation and the rate of the process depends on the electron density, <em>Ne</em>, the concentration of CO₂, and the reduced electric field, <em>E</em>/<em>N</em>. A self-consistent model was established to describe the CO₂ decomposition process based on these parameters. The model gave the microscopic description of the discharge in terms of the electron energy distribution function (EEDF) and electron mean energy <em>Te</em>, electron density <em>N e</em>, and dissociative rate coefficients. In addition, the CO₂ decomposition rate depends on all complex gas reactions during the discharge. A simplified set of major gas reactions was used to describe the rate of CO₂decomposition in the discharge. The validity of the model was successfully verified by comparing the calculated results with the experimental results. The discharge characteristics such as <em>T_e, N_e</em>, and <em>E</em>/<em>N</em>, were determined by using the Langmuir probe technique, while the discharge temperature, <em>T_g</em>, was determined by using the CO rotational temperature that was obtained from the CO rotational emission spectrum, and compared with results obtained from the thermocouple measurements. The steady-state gas composition was measured using a quadrupole mass spectrometer. Measurement of gas composition in the discharge condition was within 5% of the prediction from the model. Due to a high power efficiency to decompose CO₂ by using an RF discharge, one direct application of the study is to produce oxygen on the planet Mars. In such an experiment, oxygen was extracted and diffused through a silver membrane used as one of the electrodes during discharge. The oxygen flux produced by the present discharge condition was shown to reach about 5.0 × 10⁻¹⁴cm⁻²s⁻¹. The study of the CO₂ decomposition can be used in developing the optimum RF discharge conditions that yield the maximum oxygen flux production.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date.available

2002

Author dc:creator

• Dinh, Thao Hoang

Contributors dc:contributor

• Leposava Vuskovic
• Charles I. Sukenik
• Gail E. Dodge
• Gary E. Copeland
• Robert L. Ash

• Capacitively coupled
• Carbon dioxide
• Decomposition
• Radio-frequency discharge
• Atomic, Molecular and Optical Physics
• Fluid Dynamics
• Plasma and Beam Physics

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9780493713014

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:physics_etds-1037