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 ET42: Thermal Plasmas: Arcs, Jets, Switches, Others |
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Chair: Carmen Guerra-Garcia, MIT Room: Virtual GEC platform |
Tuesday, October 5, 2021 2:00PM - 2:15PM |
ET42.00001: Kinetic models of ESD spark resistance in atmospheric pressure gases John W Rose, Mark C Zammit, Julie Jung, Amanda J Neukirch, Claudia A Schrama, Liam Pocher, Travis Peery, James P Colgan, Charles G Durfee, Jonathan Mace Electrostatic discharge (ESD) can create hazards through the rapid breakdown of an air gap between charged objects. Sensitive devices within the discharge circuit can be exposed to short rise-time, high current pulses produced by the formation of a spark channel bridging the gap. The collapse in the electrical resistance of the channel occurs through the mechanisms of ionization degree increase and hydrodynamic expansion. Under the low temperature, atmospheric pressure conditions of the formation phase of the spark, the ionization can be in non-equilibrium with the gas temperature, thus requiring a kinetic approach to model the populations of charged species. |
Tuesday, October 5, 2021 2:15PM - 2:30PM |
ET42.00002: Measuring time dependence of channel resistance for threshold electrostatic discharge Claudia A Schrama, Sarah Hinnegan, John W Rose, Jonathan Davis, P. David Flammer, Charles G Durfee Electrostatic discharge (ESD) from charged objects can be hazardous around electronics and combustible materials. Our group is using numerical models and experiments to better understand the energy that transfers through an threshold ESD channel. We constructed a low-inductance ESD discharge chamber that includes a storage capacitor and current-viewing resistor. While the spark resistance just after the initial breakdown can be measured by fitting to the the inductive decay of the current, at longer times the stored charge is depleted. To measure the conductivity for the later times we added a second storage capacitor in parallel that discharges slowly through a current-limiting resistor. By measuring the voltage on both sides of this resistor we can measure the current and voltage across the spark, and thereby estimate the resistance of the ESD channel as gas settles back down and the channel closes. We show, in air and argon, that the resistance of the spark gap is low during the inductive ringing, 3Ω, and quickly rises to 10Ω during the first 6μs after discharge. The resistance climbs exponentially to 200kΩ over 300μs. Using a fast gated camera we image the ESD to estimate the radius versus of time to gather information on the recombination process. LANL Publication ID: LA-UR-21-25764 |
Tuesday, October 5, 2021 2:30PM - 2:45PM |
ET42.00003: Fluctuation Phenomena in Planar Thermal Plasma Jet by Diode-Rectified AC Arc Discharge Manabu Tanaka, Takafumi Okuma, Takayuki Watanabe, Tsugio Matsuura, Juan Pablo Trelles, Masaya Shigeta Planar Thermal Plasma Jet as an innovative thermal plasma source has been successfully developed on the basis of AC arc with diode-rectification technique. The purpose of the present work is to investigate fluctuation phenomena in this innovative system. Second purpose is to investigate feasibility of this system in surface treatment applications. Arc discharge was generated among 10 electrodes, which were placed in a line. These electrodes were configurated by 4 AC electrodes, 4 diode-rectified electrodes, a cathode, and an anode. Plasma jet fluctuation was successfully visualized by the high-speed camera system at framerate of 10,000fps. Two synchronized high-speed camera observations with arc voltage and current measurement revealed the periodical plasma jet fluctuation. Correlation between the arc fluctuation and plasma jet fluctuation was studied. Obtained results suggest that the planar thermal plasma jet in diode-rectified AC torch expands the possibility of thermal plasma utilization in industrial field. |
Tuesday, October 5, 2021 2:45PM - 3:00PM |
ET42.00004: Numerical Study on Modulation Induced Entrainment Gas Flow and its Promotion of Nanopowder Synthesis in Pulse-Modulated Induction Thermal Plasmas Yasunori Tanaka, Ryutai Furukawa, Yurina Nagase, Tomoya Fuwa, Yusuke Nakano, Tatsuo Ishijima, Shiori Sueyasu, Shu Watanabe, Keitaro Nakamura A numerical study was conducted for our unique and original method for PMITP+TCFF method for high-production rate nanopowder synthesis. The PMITP is pulse-modulated induction thermal plasma, while TCFF is time-controlled feedstock feeding (TCFF). The PMITP provide a periodically alternating thermal plasma fields between an extremely high-temperature plasma in on-time and a relatively low-temperature plasma in off-time. Feedstock particles are intermittently injected synchronized with on-time of the PMITP for efficient evaporation of feedstock during on-time and for efficient nucleation of nanoparticles during off-time. The developed numerical model combines the calculations of the PMITP field, dynamics of feedstock particles with two-way interactions between PMITP and feedstock particles, and the moment transport for aerosol considering homogeneous nucleation, heterogeneous condensation. Using the developed method, we newly found that modulation of the thermal plasma field can induce strong entrainment gas flow downstream of the plasma torch, which can remarkably promote nucleation of nanoparticles. This entrainment gas flow can be controlled by modulation conditions. |
Tuesday, October 5, 2021 3:00PM - 3:15PM |
ET42.00005: High-Speed Visualization of Temperature Fluctuation of Diode-Rectified Multiphase Ac Arc near the Electrodes Chang Junjie, Takemoto Yuki, Suenaga Takuya, Tamae Aika, Tanaka Manabu, Watanabe Takayuki, Matsuura Tsugio, Ueda Tsuguo, Tozaki Hideki, Trelles Juan-Pablo, Shigeta Masaya Diode-rectified multiphase AC Arc (DRMPA) has been developed to solve the electrode erosion of conventional multiphase AC Arc (MPA) in recent years. Arc temperature, as one of the most important parameters in the application of MPA, has been investigated in previous works. High-speed camera system with band-pass filters (BPF) was successfully developed to measure the fluctuated temperature of MPA. However, its measurement range of the arc temperature was limited and the highest limitation was lower than 15,000 K. This originated from the fact that the line emissions from atomic argon were only considered. In the present study, a new method to measure the arc temperature considering line emissions as well as continuum emissions is established to elucidate near-electrode temperature fluctuation in the DRMPA. The BPF of 440 ± 5 nm and 480 ± 5 nm, which involve the line emissions from singly ionized argon and strong continuum emissions, have been used in this work. The arc temperature near the electrodes fluctuated in the range from 15,000 K to 20,000 K. This result can serve as a reference for the mechanism of electrode erosion and the industrial application of DRMPA. |
Tuesday, October 5, 2021 3:15PM - 3:30PM |
ET42.00006: High Spatial Resolution Measurement of Electric Field in Positive Secondary Streamer Discharge under Atmospheric-Pressure Air Yuki Inada, Tatsutoshi Shioda, Ryosuke Nakamura, Mitsuaki Maeyama, Akiko Kumada, Ryo Ono Electric field measurement of non-equilibrium atmospheric-pressure plasma is crucially important for systematic understanding of the production mechanisms of reactive species. However, the electric field measurement has never been achieved for a streamer discharge under atmospheric-pressure air, due to its irreproducible, complex branching structure. Further, low spatial resolution of conventional electric-field sensors has prevented precise determination. Here, the electric field measurement was first achieved for the streamer discharge by the development of two original apparatuses: a multi-anode plasma generator capable of reproducibly realizing a non-branching, straight streamer discharge and an electric-field induced second harmonic (E-FISH) generation sensor with one-order-superior spatial resolution. The precise electric field measurement demonstrated that in an initial phase of the secondary streamer discharge, the electric field inside the discharge was 100 Td, which was comparable to previous simulation results. On the other hand, the electric field in the later phase showed a decrease with increasing time and finally, it reached as low as 70 Td. Such a gradual decrease has never been predicted in the previous simulation studies. The unpredicted time evolution of the electric field suggested that many reactive species were generated selectively in the initial phase, e.g., N2(C), which is the main source of optical emission from the secondary streamer discharge. |
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