Bulletin of the American Physical Society
66th Annual Gaseous Electronics Conference
Volume 58, Number 8
Monday–Friday, September 30–October 4 2013; Princeton, New Jersey
Session FT2: High Pressure Discharges: Dielectric Barrier Discharges, Coronas, Breakdown, Sparks II |
Hide Abstracts |
Chair: Ann Bourdon, Laboratoire EM2C Room: Ballroom II |
Tuesday, October 1, 2013 3:30PM - 3:45PM |
FT2.00001: Plasma chemistry in CO$_{2}$ dielectric barrier discharges F. Brehmer, S. Welzel, M.C.M. van de Sanden, R. Engeln Plasma-assisted gas phase conversion in non-thermal environments is increasingly being considered as promising technology for fuel production from CO$_{2}$ and hydrogen containing sources. Particularly the rate-limiting activation of CO$_{2}$ is suggested to be tackled in plasmas at (sub-)atmospheric pressure conditions without the admixture of carrier gases. Therefore CO$_{2}$ dielectric barrier discharges were studied to assess conversion yields and reaction mechanisms. The CO$_{2}$ discharges were resonantly excited at around 100 kHz in a flow-tube lab-scale reactor designed to facilitate time-resolved in-situ optical emission and infrared laser absorption spectroscopy. Complementary analysis of the gas phase constituents using ex-situ FT-IR spectroscopy and a thorough electrical characterisation were carried out. The CO conversion yields were typically below 5{\%} and hence in-line with similar studies. The energy efficiency can be uniformly described for different external plasma parameters (e.g. flow rate, power input, excitation frequency) as function of the specific energy input. Special attention was paid to the non-negligible formation of by-products such as O$_{3}$ and O$_{2}$ which suggests an inefficient recycling of atomic oxygen in secondary CO$_{2}$ dissociation reactions. [Preview Abstract] |
Tuesday, October 1, 2013 3:45PM - 4:00PM |
FT2.00002: Study and Control of Various Corona Modes in an Atmospheric Pressure Weakly Ionized Plasma Reactor Using a Current Sensor Characterized by a Broad Frequency Band Rokibul Islam, Patrick Pedrow, William Lekobou, Karl Englund A broad band current sensor is being used to monitor the various phenomena (primary streamers, secondary streamers, back corona, etc.) associated with an atmospheric pressure needle-array-to-grounded-screen corona discharge. The reactor consists of a PVC tube and the needle array consists of nickel coated steel electrodes with radius of curvature about $50\mu m$. The grounded screen is made from stainless steel mesh and applied voltage has a frequency of 60 Hz with an RMS value ranging from 0 to 10kV. The voltage sensor is a resistive divider and the current sensor is a viewing resistor with value 50$\Omega$. The feed gas stream is presently (argon $+$ acetylene) or (argon $+$ oxygen) with the argon acting as carrier gas and the acetylene and oxygen acting as precursor gases. Voltage and current are captured with a LeCroy 9350AL 500MHz oscilloscope and analyzed with Matlab using digital signal processing algorithms. The goals of the research are 1) to measure reactor electrical power on a real time basis; 2) to provide real time control of the applied voltage and thus avoid spark conditions; and 3) to identify the various corona modes present in the reactor. Processing of substrates takes place downstream from the grounded screen, outside of the harsh corona discharge environment. [Preview Abstract] |
Tuesday, October 1, 2013 4:00PM - 4:15PM |
FT2.00003: Simulating the inception of pulsed discharges near positive electrodes Jannis Teunissen, Ute Ebert With 3D particle simulations we study the inception of pulsed discharges near positive electrodes. In different geometries, we first determine the breakdown voltage. Then we study the probability of inception for a fast voltage pulse. This probability mostly depends on the availability of seed electrons to generate the initial electron avalanches. These results are compared with experimental observations. Then we investigate how the shape of a starting discharge affects its further development. In particular, we discuss the formation of so-called ``inception clouds.'' [Preview Abstract] |
Tuesday, October 1, 2013 4:15PM - 4:30PM |
FT2.00004: Investigation of positive streamers by double pulse experiments Sander Nijdam, Eiichi Takahashi, Aram H. Markosyan, Ute Ebert Streamer discharges are influenced by background ionization and other effects of previous discharges. We have studied the influence of repeating positive streamer discharges by applying two subsequent high voltage pulses with a variable interval (200~ns to 40~ms) between them. The discharges are studied with two ICCD cameras that image the discharge during either the first or the second voltage pulse. Experiments have been performed in a 103~mm point-plane gap at a pressure of 133~mbar in artificial air, pure nitrogen and pure argon. We have found a range of phenomena that depend on the inter-pulse time $\Delta t$. For small $\Delta t$, (below 1~$\mu s$ for air and nitrogen and below 15~$\mu s$ for argon) the streamers just continue their old paths. At larger $\Delta t$ the conductivity has decreased too much for such continuation. However, parts of the old paths do glow up again like secondary streamers. At still larger $\Delta t$ (roughly above 2.5~$\mu s$ for air and 30~$\mu s$ for nitrogen) new channels appear. At first they avoid the entire area of the previous discharge; next they follow the edges of the old channels; then they start to follow the old channels exactly and finally ($\Delta t> 1$~ms) they become fully independent of the old paths. [Preview Abstract] |
Tuesday, October 1, 2013 4:30PM - 4:45PM |
FT2.00005: Electric field of atmospheric pressure plasma jet impinging upon a surface and electrical properties of the jet source Ana Sobota, Olivier Guaitella, Enric Garcia Caurel, Antoine Rousseau We report on experimentally obtained values of the electric field magnitude of an atmospheric pressure plasma jet impinging upon a dielectric surface. The results were obtained using Pockels technique, on a BSO crystal. The electric field is a function of the gas flow and the area over which the discharge spreads on the dielectric surface. A coaxial configuration of the plasma jet was used, driven by 30 kHz sine voltage, in He flowing at 100-900 SCCM. In this geometry we found 2 modes of operation, a low-power mode stable at one plasma bullet emitted per period and the unstable high-power mode featuring additional micro-discharges. In addition to the electric field measured in the low-power mode, electrical characterization of the jet source will be presented, together with the manner in which properties of the setup can influence the jet and vice versa. The distinction will be made between the plasma jet in room atmosphere and the plasma jet interacting with a dielectric surface. [Preview Abstract] |
Tuesday, October 1, 2013 4:45PM - 5:00PM |
FT2.00006: Discharge inception in atmospheric air above the breakdown field Anbang Sun, Jannis Teunissen, Ute Ebert Streamers play an important role in creating the path of lightning and sprites. They also have wide applications in industry. In this work, we use a 3D particle code to investigate streamer formation in atmospheric air, in a homogeneous electric field above the breakdown threshold. We include the effect of natural background ionization and of photoionization. We see that numerous avalanches start from different locations, these avalanches overlap and screen the electric field in the interior of discharges. Finally, no isolated streamer forms in this region. We give an analytical estimation of the screening ionization time which is a generalization of the Maxwell relaxation time in ionizable media. Our results are very different from so-called double-headed streamers that were found in previous fluid models. Our simulations are in agreement with recent experimental observations. [A. Sun et al., Geophys. Res. Lett., 40, 1-6 (2013)]. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700