DocumentCode :
227892
Title :
Ignition dynamics in microwave-generated microplasmas
Author :
Hoskinson, Alan R. ; Yared, Alexander ; Hopwood, Jeffrey
Author_Institution :
Electr. & Comput. Eng., Tufts Univ., Medford, MA, USA
fYear :
2014
fDate :
25-29 May 2014
Firstpage :
1
Lastpage :
1
Abstract :
Summary form only given. Microwave resonators are used to generate microplasmas in atmospheric-pressure argon. We investigate the ignition and filamentation dynamics in two systems with different techniques for modulating the microwave power: a diode-switched resonator in an array1 with constant input power, and a single resonator with pulsed input power. The plasma evolution is examined using time-resolved photography and spectroscopic gas temperature measurements over time scales from tens of nanoseconds up to milliseconds.The two discharge systems exhibit markedly different behaviors at sub-microsecond time scales, corresponding to the different switching mechanisms. The diode-switched microplasma exhibits a relatively slow, monotonic rise in intensity due to a combination of electronic and ionization processes. In contrast, the pulsed microplasma experiences an initial spike in emission intensity due to the deposition of stored microwave energy into the plasma and electron overheating2. At time scales longer than a few tens of microseconds, the plasma dynamics in the two systems become quite similar. The microplasmas continue to grow in both intensity and size over several milliseconds. These dynamic behaviors are qualitatively explained by localized heating of the neutral gas, and are expected to appear in many types of microplasmas. We also discuss practical limits to plasma equilibration time in different microplasmas.
Keywords :
argon; high-frequency discharges; ignition; microwave resonators; plasma diagnostics; plasma radiofrequency heating; plasma temperature; Ar; atmospheric-pressure argon; constant input power; diode-switched microplasma; diode-switched resonator; discharge systems; dynamic behaviors; electron overheating; electronic processes; emission intensity; filamentation dynamics; ignition dynamics; initial spike; ionization processes; localized heating; microwave power; microwave resonators; microwave-generated microplasmas; neutral gas; plasma dynamics; plasma equilibration time; plasma evolution; pressure 1 atm; pulsed input power; pulsed microplasma; single resonator; spectroscopic gas temperature measurements; stored microwave energy deposition; submicrosecond time scales; switching mechanisms; time-resolved photography; Discharges (electric); Educational institutions; Electromagnetic heating; Ignition; Microwave theory and techniques; Plasmas; Switches;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Plasma Sciences (ICOPS) held with 2014 IEEE International Conference on High-Power Particle Beams (BEAMS), 2014 IEEE 41st International Conference on
Conference_Location :
Washington, DC
Print_ISBN :
978-1-4799-2711-1
Type :
conf
DOI :
10.1109/PLASMA.2014.7012591
Filename :
7012591
Link To Document :
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