Bulletin of the American Physical Society
74th Annual Gaseous Electronics Conference
Volume 66, Number 7
Monday–Friday, October 4–8, 2021;
Virtual: GEC Platform
Time Zone: Central Daylight Time, USA
Session HW11: Atmospheric and High Pressure Plasmas: Jets and Gliding Arcs II |
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Chair: Ryan Gott, NASA Kennedy Room: Virtual GEC platform |
Wednesday, October 6, 2021 8:00AM - 8:15AM |
HW11.00001: PLIF study of arc discharge localization in mixing layer of high-speed flow Sergey Leonov, Skye Elliott Demand for hypersonic airbreathing propulsion systems has led to intense study of the air-fuel mixing and ignition dynamics in high-speed combustors. In this work the plasma injection module (PIM), coupling an arc discharge (Quasi-DC) to a fuel jet, is used for ignition. Prior results demonstrated a significant extension of flameholding limits using PIMs, yet mechanisms yielding this effect need further study. This work focuses on one of the key aspects of PIM-related physics: longitudinal arc discharge localization in a fuel/air mixing layer. The PLIF technique along with high-speed visualization and optical emission spectroscopy were employed in this study. Typical test parameters were: flow M=2, P0=1.6-3.2bar, T0=300-750K, plasma filament length up to 100mm at current I=3-5A and gap voltage U=0.6-1.5kV with translational temperature Tg=3.5-6kK. Experimental data and analysis of the plasma composition/electrical conductivity indicate that, under favorable test geometry, the constricted plasma strives to locate within the mixing layer and not in the fuel jet or in the core airflow. The mechanism of arc plasma localization is considered as a trade-off between electrical and thermal conductivities in a carbon-containing plasma with a gradient concentration of the components. |
Wednesday, October 6, 2021 8:15AM - 8:30AM |
HW11.00002: Electrodeless Atmospheric Secondary Induced Ionization plasma jet – EASII-jet Sylvain Iseni, Alibi Baitukha, Cécile Pichard, Nelly Bonifaci, Ahmed Khacef Non-equilibrium atmospheric pressure plasma jet (APPJ) devices are promising plasma sources for many kinds of applications. APPJs have already demonstrated their unique potential to trigger biological responses valuable in medicine and biology. It has also been involved in various application such as water and liquid activation, agriculture, surface modifications and active flow control. Operating in ambient air, APPJs can be easy to design and to implement in to already existing industrial systems. Their high potential to produce localized highly reactive oxygen and nitrogen species (RONS) is of significant interest in many fields of applications. Usually made of a –transparent– dielectric tube of a few centimeters long, it is equipped with a pair of electrodes connected to a HV power supply. Noble gas (typically helium or argon) flows into it at flow rate in the order of a liter per minute. The latter having a lower ionization energy threshold than air, ionization waves (IW) are produced in the vicinity of the power electrode. The IW propagates within the He flowing into the tube before to expand outside guided by the He plume and forming a luminous plasma plume of a couple of cm long. |
Wednesday, October 6, 2021 8:30AM - 9:00AM |
HW11.00003: Effect of jet polarity on charging of a dielectric target: simulations and experiments Invited Speaker: Pedro Viegas The dynamical charging of a dielectric BSO target by an atmospheric pressure low-temperature plasma jet is addressed numerically and experimentally, using a two-dimensional fluid model and Mueller polarimetry measurements. The jet geometry is the same in experiments and simulations. The target is placed perpendicularly to the jet propagation and the jet is powered by rectangular pulses of applied voltage of different polarity and magnitude. The axial component of electric field inside the target is quantitatively compared between simulations and experiments, yielding excellent agreement for every studied condition, during and after the pulses. The electric field inside the target is closely related to the charge deposition on the target surface. It is shown that the spatial distribution of electric field inside the target during the pulse takes a different shape according to the jet polarity. Shortly after the pulse, charge deposition of opposite signal to the one of the applied voltage takes place. Finally, in the long time-scales in between pulses, the distributions of leftover surface charges on the target surface and leftover electric field inside the target are dependent on the polarity and magnitude of applied voltage. The discharge dynamics and the reasons behind these differences are investigated. |
Wednesday, October 6, 2021 9:00AM - 9:15AM |
HW11.00004: Energy efficiency of voltage waveform tailoring for the generation of helium metastable species in RF plasma jets Ihor Korolov, Donkó Zoltán, Gerrit Hübner, Yue Liu, Thomas Mussenbrock, Julian Schulze Atmospheric pressure capacitively coupled radio frequency discharges operated in He/N2 mixtures and driven by single frequency as well as tailored voltage waveforms are investigated using a reference microplasma COST-jet. For each case, the dissipated power is measured based on a careful calibration procedure of voltage and current measurements. The results are compared to PIC/MCC simulation results and a very good agreement is found. We demonstrate that Voltage Waveform Tailoring (VWT) - in contrast to the classical single-frequency operation - does not only provide better control of the generation of metastable species (He-I 23S1) but also provides significantly better energy efficiency of such processes. |
Wednesday, October 6, 2021 9:15AM - 9:30AM |
HW11.00005: Effect of structured electrodes and electrode materials on electron power absorption and helium metastable densitiy in microplasma jets driven by tailored voltage waveforms Gerrit Hübner, Lena Bischoff, Ihor Korolov, Zoltan Donko, Yue Liu, Thomas Mussenbrock, Julian Schulze Atmospheric pressure capacitively coupled radio frequency plasmas are widely used for different applications, e.g., biomedical surface treatment and etching/deposition. The main challenge is to generate and selectively control the application relevant excited species. In this work, we use a reference microplasma COST-jet constructed using different electrode materials and structured electrodes. The jet is operated in He/N2 and He/O2 mixtures and driven by single frequency as well as tailored voltage waveforms. We use Tunable Diode Laser Spectroscopy (TDLAS) to monitor the density of He-I 23S1 metastables and Phase Resolved Optical Emission Spectroscopy (PROES) to study the spatio-temporal dynamics of energetics electros in the COST-Jet. The experimental results are compared to kinetic (PIC/MCC) and fluid simulation results. We demonstrate that the choice of the material and topology for the powered and grounded electrode influences the electron heating dynamics, and as a consequence the generation of metastable species. Furthermore, we show that the combination of Voltage Waveform Tailoring and structured electrodes allows us to greatly influence electron power absorption dynamics and the generation of helium metastables inside the used trenches. |
Wednesday, October 6, 2021 9:30AM - 9:45AM |
HW11.00006: Simulation and modeling of a non-neutral discharge regime of atmospheric pressure plasma jets Maximilian Klich, Sebastian Wilczek, Zoltan Donko, Ralf Peter Brinkmann In contrast to low-pressure plasmas, where the Debye length λD and the discharge length L differ by several orders of magnitude, many atmospheric pressure plasmas inherit comparable scales for these quantities. As a result of this characteristic, atmospheric pressure plasmas can fail to develop a quasi-neutral bulk region and operate within a non-neutral discharge regime. We observe and analyze this operation regime by applying a one-dimensional hybrid particle-in-cell/Monte Carlo collisions (PIC/MCC) simulation for the cross-section of the jet. The results indicate that the electrons become organized within a soliton-like Gaussian-shaped structure. Their dynamics are dominated by the dynamics of this soliton structure, for which a naive analytical model was developed. Furthermore, a direct comparison between the analytical model and the simulation results is achieved that validates the conclusions drawn from the analysis of the model. The main goal of our work is to analyze the electron dynamics of the aforementioned non-neutral discharge regime of capacitively coupled atmospheric pressure plasma jets. |
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