Bulletin of the American Physical Society
75th Annual Gaseous Electronics Conference
Volume 67, Number 9
Monday–Friday, October 3–7, 2022;
Sendai International Center, Sendai, Japan
The session times in this program are intended for Japan Standard Time zone in Tokyo, Japan (GMT+9)
Session ER5: Jets and Gliding Arcs |
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Chair: Zaka ul-Islam Mujahid, Ruhr University Bochum, Germany Room: Sendai International Center Hagi |
Thursday, October 6, 2022 4:00PM - 4:15PM |
ER5.00001: N2 vibrational kinetics in near atmospheric pressure nanosecond-pulsed plasma jet: simulations validated against measurements Youfan He, Jan Kuhfeld, Nikita D Lepikhin, Dirk Luggenhoelscher, Uwe Czarnetzki, Vasco Guerra, Ralf Peter Brinkmann, Andrew R Gibson, Efe Kemaneci In this contribution, near atmospheric pressure nanosecond-pulsed plasma jets are investigated by a zero-dimensional volume-averaged model. The model calculations of N2(v<58) plasma are validated against the measured vibrational level densities (v<5). The Vibrational-Vibrational (V-V) and Vibrational-Translational (V-T) rate coefficients are determined from diverse theoretical approaches, i.e. the V-V kinetics from the simple form of an harmonic oscillator (sfHO), the Schwartz–Slawsky–Herzfeld (SSH) and the Forced Harmonic Oscillator (FHO). The V-T rate coefficients are determined via the sfHO and the fit functions of the quasi-classical trajectory and semi-classical calculations. The influences of these different approaches on the simulated time-dependent vibrational distribution functions are presented. A limited influence on the low vibrational level densities (v<5) is observed, whereas larger differences are shown in the concentrations of higher levels by using the aforementioned different approaches. The sensitivity of the vibrational distribution function to the neutral wall reaction probabilities is revealed, e.g. the wall quenching of the vibrationally excited nitrogen molecules plays a role in the intermediate and high level densities. |
Thursday, October 6, 2022 4:15PM - 4:30PM |
ER5.00002: Optical diagnostic and reactive species characterization of atmospheric pressure argon plasma jet under various operating conditions Psnsr R Srikar, Shaik Mahamad Allabakshi, Shihabudheen M Maliyekkal, Reetesh K Gangwar Atmospheric pressure plasma jets (APPJs) have attracted significant research attention due to their simple design and low fabrication cost. Several studies have been conducted to demonstrate the viability of APPJs in various applications such as surface treatment, biomedical, material synthesis, and water treatment. However, tuning the plasma operating parameters is critical to producing the optimum amount of reactive chemical species (RCS) required for a specific application without deviating from the nonthermal nature of the plasma. This is possible only by understanding inter relationship between the plasma parameters and their influence on the RCS generation. In this work, we developed a flexible APPJ reactor setup and performed the plasma diagnostic using optical emission spectroscopy coupled with a collisional radiative model. The information of electron temperature (Te), density (ne) was estimated as a function of various operating parameters such as nozzle size, flow rate, and gas mixture. The characterization of RCS is also carried out under different operating conditions. A correlation between operating conditions such as jet nozzle size, flow rate, gas medium, and operating electrical signal, and the production of reactive chemical species is established. A detailed description of the APPJ setup, optical emission spectroscopy measurements, collisional radiative model, and RCS characterization will be presented during the conference. |
Thursday, October 6, 2022 4:30PM - 4:45PM |
ER5.00003: Investigation of multi-periodic self-trigger plasma in a AC-driven Atmospheric Pressure Plasma Jet Hang Yang, Antoine Rousseau In this work, a helium plasma jet driven by 15~18kHz sinusoidal voltage ignites multi-periodic self-triggered mode or random mode depending on applied voltage, driven frequency and inter-electrode gap distance. Most of the observed multi-periodic bullets operate every 2 or 3 sinusoidal period. Such bullets show similarities with pulsed operating mode, having a jitter less than 100 ns. The presence of an outer grounded electrode ring is a key parameter permitting the ignition of multi-periodic bullets; it also enhances the propagation length up to 8 times. Fast imaging reveals that the negative bullets and positive bullets have different ignition mechanisms. Self-triggered pre-ionization waves are observed to propagate back and forth in the inter-electrode gap region before the formation of negative bullets; The negative bullets enables the ignition of positive bullets. Bullet velocities for different polarities and gap distance are compared using optical emission spectrum. |
Thursday, October 6, 2022 4:45PM - 5:00PM |
ER5.00004: O2 influence on the spatio-temporal density of Ar(1s5) in micro-plasma jets with varying shieldings Duarte Gonçalves, Gérard Bauville, Pascal Jeanney, Luis L Alves, Mário Lino da Silva, João Santos Sousa, Stéphane Pasquiers Argon micro-plasma jets (AMPJs) can be created by streamers propagating along the jet [1], which excite argon species that interact with air [2] or targets [3]. Jets lead to the admixture of ambient species into the main flow, resulting in discharges produced in evolving gas compositions. |
Thursday, October 6, 2022 5:00PM - 5:15PM |
ER5.00005: Influence of Voltage Pulse Off-Time on the Discharge Characteristics in Surface-Launched Plasma Bullets Koki Sasaki, Atsumu Matsumoto, Jun-Seok Oh, Tatsuru Shirafuji We have investigated propagation characteristics of surface-launched plasma bullets (SLPBs), which are vertically launched from dielectric surface. We conducted our experiments particularly focusing on the influence of voltage pulse-off time on the plasma bullets propagation characteristics by using an ICCD camera. Comparison of sequential images captured with the ICCD camera in different pulse off-times of 28 µs and 2 µs showed that SLPB's velocity and size increase as the pulse off-time becomes shorter as opposed to the bullet-propagation characteristics observed in conventional APPJs. These results indicate that the SLPBs may propagation scheme is somewhat different from those of conventional plasma bullets launched from a tube. The reason for our results may be related to the charge accumulation on the inner wall of the quartz tube and/or in the gas phase chemistry where the previous bullet propagated. Details will be discussed based on the ICCD images captured at both positive- and negative-pulse-rise edges. |
Thursday, October 6, 2022 5:15PM - 5:30PM |
ER5.00006: Experiments and numerical simulation on the plasma bullets launched vertically from a dielectric surface Tatsuru Shirafuji, Jun-Seok Oh We have found that plasma bullets can be launched vertically from a plane surface of a dielectric plate, as opposed to the fact that conventional plasma bullets are mostly launched from a nozzle of a dielectric tube. We call such plasma bullets as Surface-Launched Plasma Bullets (SLPBs). This phenomenon has possibility to be applied to large area and/or large volume treatments by atmospheric-pressure plasma because the SLPBs propagates as sheet-like bullets. However, the SLPBs were available only for high voltage-rise rate greater than 30 kV/s. For understanding the reasons of this limitation, we are conducting numerical simulation of the SLPB propagation with different voltage-rise rates and discuss the reason of the limited availability of SLPBs from the viewpoint of trade-off between the rise rate in the local ionization rate and the loss of the local space charges near the dielectric surface at the very initial stage of launching the plasma bullet. |
Thursday, October 6, 2022 5:30PM - 5:45PM |
ER5.00007: Properties of an atmospheric He-based nanosecond jet discharge Nikolay Britun, Peterraj Dennis Christy, Vladislav Gamaleev, Shih-Nan Hsiao, Masaru Hori An atmospheric repetitive discharge with 10 ns current pulse width and 3×1011 V/s voltage growth rate operating in jet geometry in He with admixtures is studied by optical emission spectroscopy methods. The measurements were employed in the discharge, post-discharge and jet regions. Rotational and vibrational temperatures of the excited discharge molecules, the electron density (Ne) and the electric field (E-field) were measured. It is found that Ne reaches nearly 1016 cm-3 in the plasma pulse. Upon more careful fitting, it was found that Hβ line reveals double-Lorentzian profile corresponding to two electron density groups. The low-density group contains density below 1014 cm-3 showing no decent trends, whereas the high-density group shows a clear density decay after the peak (avalanche). The high-density electron cloud leads to formation of a microscopic E-field of about 30 kV/cm between the electrodes right after the pulse. At the same time, in the discharge tube the E-field is directional with slight domination of radial component. Its value is roughly twice lower as compared to the one found in the discharge area. The gas temperature does not exceed about 320 K during the whole discharge cycle. All in all, the low gas temperature, high peak electron density, fast ionization wave propagation and the accompanying directional electric field make ns- jet discharges good candidates for remote surface treatment. |
Thursday, October 6, 2022 5:45PM - 6:00PM |
ER5.00008: Micro electric fields detection improvements: Steps toward tailoring cold atmospheric pressure plasma Stephan Reuter Cold atmospheric plasma science is a continuously growing domain. From microfabrication to medicine, air and surface decontamination, agriculture, material synthesis, food processing, among many more, applications of this omnipresent, yet to broad society invisible technologies seems limitless. The knowledge about plasma sources and the underlying physics is constantly improved with new designs and multidisciplinary applications. The ability of cold atmospheric pressure plasma to generate reactive species relevant for the most prominent applications, such as wound healing, pathogen inactivation, methane reforming, originates from the plasma's electric field characteristics. It is thus of the utmost importance to have an efficient, sensitive, and high-resolution detection techniques to determine the plasmas electric field time and space resolved. This allows to unravel its role in the behavior of plasmas for each respective application. Our method of choice is electric field-induced second harmonic, a by now well-established nonperturbative technique for measuring the amplitude and orientations of cold atmospheric plasma electric fields. Although E-FISH allows for a good and tunable time resolution, depending on the pulse's characteristics of the used laser, it has been shown that E-FISH presents some issues with spatial resolution and sensitivity. Work on enhancing these two characteristics of E-FISH have been made by our team and collaborators. Using a femtosecond laser, novel approaches were developed and optimized. The presented results confirmed the improvement of the electric field detection technique, the E-FISH, and will certainly deepen our knowledge on the spatio-temporal electric field distribution of cold atmospheric plasma. |
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