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Characteristics and applications of high pressure microplasmas.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Characteristics and applications of high pressure microplasmas.
Author:	Hsu, David Dah-Wei.
Description:	120 p.
Notes:	Chair: David B. Graves.
Notes:	Source: Dissertation Abstracts International, Volume: 64-09, Section: B, page: 4493.
Contained By:	Dissertation Abstracts International64-09B.
Subject:	Engineering, Chemical.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3105243
ISBN:	0496528106

Characteristics and applications of high pressure microplasmas.
Hsu, David Dah-Wei.

Characteristics and applications of high pressure microplasmas. [electronic resource] - 120 p.

Chair: David B. Graves.

Thesis (Ph.D.)--University of California, Berkeley, 2003.

A microhollow cathode discharge (MHCD) operates at high temperatures and power densities. The peak neutral temperature of MHCDs can reach 2,000 K. The discharges operate with powers of 1--5 W, and thus power densities of up to 60--300 kW/cm3. These thermal properties suggest that an MHCD would be well suited to endothermic, microscale chemical reactions. Unlike resistive heaters, the electrical power of the microdischarge heats the gas directly, offering the possibility of higher peak temperatures and greater energy efficiency. Ammonia decomposition is a highly endothermic reaction. Conversion is largely dependent on the residence time of the gas in the plasma. Using published kinetic data and a plug flow reactor model, the conversion and residence time data are consistent with thermal decomposition at temperatures near 3,000 K. Decomposition of carbon dioxide into carbon monoxide and oxygen is also studied.

ISBN: 0496528106Subjects--Topical Terms:

226989
Engineering, Chemical.

Characteristics and applications of high pressure microplasmas.
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500 $a Chair: David B. Graves.
500 $a Source: Dissertation Abstracts International, Volume: 64-09, Section: B, page: 4493.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 2003.
520 # $a A microhollow cathode discharge (MHCD) operates at high temperatures and power densities. The peak neutral temperature of MHCDs can reach 2,000 K. The discharges operate with powers of 1--5 W, and thus power densities of up to 60--300 kW/cm3. These thermal properties suggest that an MHCD would be well suited to endothermic, microscale chemical reactions. Unlike resistive heaters, the electrical power of the microdischarge heats the gas directly, offering the possibility of higher peak temperatures and greater energy efficiency. Ammonia decomposition is a highly endothermic reaction. Conversion is largely dependent on the residence time of the gas in the plasma. Using published kinetic data and a plug flow reactor model, the conversion and residence time data are consistent with thermal decomposition at temperatures near 3,000 K. Decomposition of carbon dioxide into carbon monoxide and oxygen is also studied.
520 # $a Another possible application that exploits the MHCD's intense thermal properties is observation of optical emission from the discharge to detect small concentrations of perfluorinated compounds (PFCs). Because of the plasma's intense ionization and excitation, along with its suitability in endothermic decomposition reactions, light is emitted from small concentrations of the target molecule and its parts. As a proof of principle test, various concentrations of C2F6 in argon at 700 torr are flowed through an MHCD and the optical emissions are analyzed. Emissions from atomic carbon, atomic fluorine, and molecular C2 yields a detection limit of 2 ppm.
520 # $a Instabilities in these high pressure microhollow cathode discharges are not well understood. One such instability is the pulsing of current and voltage of microhollow cathode discharges with frequencies in the kilohertz range. We describe the intrinsic pulsing behavior using a model of the discharge based on an external direct current circuit, with resistor, capacitor, and inductor elements. At an elementary level, the microhollow cathode, without a plasma, behaves similar to a capacitor. (Abstract shortened by UMI.)
520 # $a One geometry used for microplasmas is the microhollow cathode. The microhollow cathode (MHC) consists of two metal electrodes sandwiching a dielectric. A cylindrical hole is drilled through all three layers. A direct current voltage is applied to one electrode and the other electrode is grounded, and the geometry allows for intense ionization and excitation. Research in this work centers on exploring applications to exploit the unique features of the MHC.
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650 # 0 $a Engineering, Electronics and Electrical. $3 226981
710 0 # $a University of California, Berkeley. $3 212474
773 0 # $g 64-09B. $t Dissertation Abstracts International
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790 1 0 $a Graves, David B., $e advisor
791 $a Ph.D.
792 $a 2003
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