Bulletin of the American Physical Society
70th Annual Gaseous Electronics Conference
Volume 62, Number 10
Monday–Friday, November 6–10, 2017; Pittsburgh, Pennsylvania
Session QR2: Diagnostics III |
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Chair: Vladimir Demidov, West Virginia University Room: Duquesne |
Thursday, November 9, 2017 8:00AM - 8:15AM |
QR2.00001: Simultaneous Diagnostic of Temperature Distribution and Electric Field induced in Dielectric Target by Atmospheric Pressure Plasma Jet Elmar Slikboer, Enric Garcia-Caurel, Ana Sobota, Olivier Guaitella A polarimetric technique is used to image the complete Mueller matrix of a sample under plasma exposure. This allows for the spatial investigation of the optical properties modified by the plasma. In particular, the birefringence of a BSO crystal contains information about the induced electric field in the target and hence about charges deposited on its surface by the discharge. Additional new findings shows simultaneously a secondary signal in the birefringence which is related to the temperature distribution. This is due to temperature induced strain. Measuring the temperature profile in the target allows for the investigation of the amount of heat that is produced in the plasma jet and transferred to the target. The heat distribution on the surface is investigated for different gas mixtures of both feeding gas of the jet as for the controlled environment in which it is placed. Simultaneously, the spatial and temporal evolution of surface electric field and charge deposition profiles are obtained. This simultaneous diagnostic helps gaining better understanding of the plasma kinetics involved in the atmospheric pressure plasma jet with different gas mixtures. [Preview Abstract] |
Thursday, November 9, 2017 8:15AM - 8:30AM |
QR2.00002: Ultrafast Laser Diagnostics to Interrogate High Pressure, Highly Collisional Plasma Environments Edward Barnat, Andrew Fierro The implementation and demonstration of laser-collision induced fluorescence (LCIF) generated in atmospheric pressure helium environments is presented in this communication. As collision times are observed to be fast (\textasciitilde 10 ns), ultrashort pulse laser excitation (\textless 100 fs) of the 2$^{\mathrm{3}}$S to 3$^{\mathrm{3}}$P (388.9 nm) is utilized to initiate the LCIF process. Both neutral induced and electron induced components of the LCIF are observed in helium afterglow plasma as the reduced electric field (E/N) is tuned from \textless 0.1 Td to over 5 Td. Under the discharge conditions presented in this study (640 Torr He), the lower limit of electron density detection is \textasciitilde 10$^{\mathrm{12\thinspace }}$ e/cm$^{\mathrm{3}}$. Spatial profiles of the 2$^{\mathrm{3}}$S helium metastable and electrons are presented as functions of E/N to demonstrate the spatial resolving capabilities of the LCIF method. [Preview Abstract] |
Thursday, November 9, 2017 8:30AM - 9:00AM |
QR2.00003: Electric Field Measurements in Nanosecond Pulse Discharges in Air over Solid and Liquid Dielectric Surfaces Invited Speaker: Igor Adamovich Electric field in nanosecond pulse discharges in ambient air is measured by picosecond four-wave mixing, with absolute calibration by a known electrostatic field. The measurements are done in a discharge between two parallel cylinder electrodes covered by quartz tubes, and in a discharge between a razor edge high-voltage electrode and a plane grounded electrode covered by a quartz plate or by a layer of distilled water. In the positive polarity discharge between the parallel cylinders, peak electric field, 140 kV/cm, considerably exceeds DC breakdown threshold. In the negative polarity discharge between the razor blade and quartz surface, the field follows the applied voltage until ``forward'' breakdown occurs, after which the field in the plasma decays due to charge separation. When the applied voltage is reduced, the field reverses direction and increases again, until the ``reverse'' breakdown occurs, producing a secondary reduction in the field. Spatially resolved measurements show that the discharge develops as a surface ionization wave. Measurements of electric field vector components demonstrate that the vertical field in the wave peaks ahead of the horizontal field. Behind the wave, the vertical field remains low, while the horizontal field is gradually reduced. In the discharge over water surface, electric field is measured for both positive and negative pulse polarities, with durations of about 10 ns and about 100 ns, respectively. In the positive polarity pulse, breakdown threshold is 85 kV/cm, and no field reversal is detected during the voltage reduction. In the negative polarity pulse, breakdown occurs at 30 kV/cm, due to much longer pulse duration, and the field reverses direction when the voltage is reduced. After the pulse, the residual field over quartz and water surfaces decays on a microsecond time scale, due to surface charge neutralization by charge transport from the plasma. The results demonstrate considerable potential of the present technique for electric field measurements in atmospheric pressure discharges, providing quantitative insight into charge transport and plasma kinetics near plasma-liquid interface. [Preview Abstract] |
Thursday, November 9, 2017 9:00AM - 9:15AM |
QR2.00004: In-situ nanoparticle detection with Coherent Rayleigh-Brillouin Scattering Alexandros Gerakis, Mikhail Shneider, Brentley C. Stratton, Yevgeny Raitses We report on the development and application of a new laser diagnostic for the in situ detection of large molecules and nanoparticles.~ This four wave mixing diagnostic technique relies on the creation of an optical lattice in a medium due to the interaction between polarized particles and intense laser fields. This diagnostic was already successfully demonstrated in atomic and molecular gaseous environments, where the different gas polarizabilities and pressures were successfully measured. Finally, using this diagnostic technique, we demonstrate the first~\textit{in situ}~measurement of nanoparticles with dimensions of few nanometers and number densities in the order of 10$^{\mathrm{12}}$ cm$^{\mathrm{-3}}$, produced in an graphitic arc discharge.~ References: 1) Gerakis, A., Shneider, M. N. {\&} Stratton, B. C. Remote-sensing gas measurements with Coherent Rayleigh-Brillouin Scattering. Appl.Phys. Lett. 109, 031112 (2016). [Preview Abstract] |
Thursday, November 9, 2017 9:15AM - 9:30AM |
QR2.00005: ABSTRACT WITHDRAWN |
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