AVS 52nd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP8
Frequency and Dimensional Scaling of Microplasmas Generated by Microstrip Transmission Lines

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Plasma Science and Technology Poster Session
Presenter: I. Rodriguez, Northeastern University
Authors: I. Rodriguez, Northeastern University
J. Hopwood, Northeastern University
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A microplasma is generated in a gap formed between the ends of a microstrip transmission line. The microstrip is fabricated in the shape of a circular ring, and the discharge gap is micromachined through the microstrip such that the device resembles a nearly closed C. This geometry resonates if microwave power is coupled to the split-ring at a frequency for which the circumference is one-half of the wavelength. At resonance, a strong electric field is generated in the discharge gap region and a microplasma may be ignited. Split-ring resonator microplasmas operating at 900 MHz have been reported in the literature@footnote 1@ and operate from 0.1 Torr to 760 Torr in air as well as inert gases. The primary advantage of this device in comparison to low frequency and DC microplasmas is the elimination of ion-induced erosion of the micro-electrodes. The ions are not accelerated toward the electrodes because the split-ring is at a constant DC potential. In addition, the ions cannot respond to the microwave field. In this presentation, we report scaling the split-ring resonator. Using an aluminum oxide substrate (@epsilon@@sub r@ = 10.2), the 900 MHz device must be 20 mm in diameter. By increasing the operating frequency to 1.8 GHz, the split-ring resonator is scaled down to approximately 10 mm. Higher frequency operation also improves the confinement of the electrons within the discharge gap by decreasing the amplitude of electron oscillation. The scaled split-ring resonator operates in argon at 1 atm using 0.3 watts supplied by a power amplifier chip from a cell phone. Electromagnetic simulations and measurements of the physical device compare favorably@footnote 2@. @FootnoteText@ @footnote 1@F. Iza and J. Hopwood, IEEE Transactions on Plasma Science, Vol. 31(4), pp. 782-787 (2003).@footnote 2@This work is supported by NSF Grant No. CCF-0403460.