Article
Physics, Applied
Sarveshwar Sharma, Nishant Sirse, Animesh Kuley, Abhijit Sen, Miles M. Turner
Summary: This study used particle-in-cell simulation to explore the dynamics of collisionless symmetric capacitive discharges operated at constant power densities, focusing on the impact of driving frequency on discharge parameters and higher harmonics generation. The simulations showed that discharge voltage decreases and discharge current increases with increasing driving frequency, with a transition frequency observed at both power densities. Changes in electron and ion energy distribution functions were also observed with variations in driving frequency, with different behavior at lower and higher power densities.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Physics, Fluids & Plasmas
E. Kawamura, M. A. Lieberman, A. J. Lichtenberg, P. Chabert
Summary: In this study, 1D particle-in-cell simulations were used to investigate the alpha and gamma modes of a capacitive nitrogen discharge. The transition from the alpha to gamma mode was characterized by an increase in density, and a decrease in electron temperature, sheath width, and sheath voltage. The simulations showed good agreement with the passive bulk model and predicted the alpha to gamma transition accurately.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Physics, Fluids & Plasmas
Pascal Chabert, Tsanko Vaskov Tsankov, Uwe Czarnetzki
Summary: This paper introduces the basics of RF discharges, covering non-magnetized capacitive and inductive RF discharges, their main concepts, and applications in various industries. It serves as an entry point for newcomers in the field and provides ample references for further study.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Physics, Fluids & Plasmas
Jing-Yu Sun, Quan-Zhi Zhang, Julian Schulze, You-Nian Wang
Summary: In weakly magnetized capacitive RF plasmas, electrons can be accelerated and returned to the electrode due to their gyromotion around an externally applied magnetic field. This magnetized RF sheath resonance effect has been studied in oxygen plasmas using kinetic particle-in-cell simulations. The resonance mechanism is strongly affected by the electronegativity of oxygen discharges, and its efficiency is particularly high at low pressure and low electronegativity. However, in strongly electronegative discharges, the resonance effect is reduced due to the influence of drift and ambipolar electric fields in the plasma bulk.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Applied
Sarveshwar Sharma, Nishant Sirse, Animesh Kuley, Miles M. Turner
Summary: Using a particle-in-cell simulation technique, this study investigates the plasma and ionization asymmetry, higher harmonics generation, and electron and ion energy distribution function in capacitive discharges excited by tailored waveforms. The simulation results demonstrate that the choice of waveform is critical for achieving maximum asymmetry and plasma density simultaneously in capacitive discharges.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Jing-Yu Sun, Xing Chen, Kai Zhao, Cheng Yuan, Xiao-Yong Lu, Fei Gao, You-Nian Wang
Summary: This study investigates the potential of radio-frequency (rf) plasma heating in enhancing ion extraction efficiency in a decaying plasma. The numerical simulations show that the application of rf power leads to a significant increase in ion extraction flux, reducing the extraction time. The increase in ion extraction flux is attributed to the enhancement of the rf electric field penetration and the elevating bulk electron temperature.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Keizo Fujimoto, Jin-Bin Cao
Summary: A new mechanism for strong electron heating in magnetic islands ejected from the reconnection current layer is proposed in this study. Full kinetic simulations in a three-dimensional system show that electrons are effectively accelerated by the non-ideal electric field generated through electromagnetic turbulence in the magnetic islands. High-energy electrons are efficiently scattered by the turbulence, leading to strong electron heating, which is consistent with recent satellite observations in the Earth's magnetosphere.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Physics, Multidisciplinary
Heesung Park, Yukinori Sakiyama, Hae June Lee
Summary: A particle-in-cell simulation is used to study capacitively coupled plasma devices, taking into account the particles' trajectories with arbitrary energy distributions and analyzing sheath dynamics accurately. By implementing the ghost grid method in the Poisson solver, curved structures can be simulated in structured grids. The transport and heating mechanisms of electrons are determined based on the two-dimensional sheath dynamics. The effects of the hollow cathode on electron transport are investigated by varying the hole shape and gas pressure. The spatial distributions of electron density and temperature are influenced by the energy relaxation length of electrons, which is determined by the energy distribution function and gas pressure. As a result, a new electron heating mode appears in the 2D structure.
FRONTIERS IN PHYSICS
(2023)
Article
Mechanics
Xian-dong Li, Tian-fei Xiao, Ming-yan Lan, Peng Zheng, Run-ze Li, Zhi-li Zhou, Le-teng Gong, Jian Li
Summary: The dynamic evolution behavior of subsonic streamers and their voltage polarity effects were investigated. The streamer development process can be divided into two stages: bottom-up period characterized by root spherical expansion and OH emission line, and top-down period characterized by head burst expansion and emission lines of H-beta, H-alpha, and O. The magnetic pinch effect on the internal plasma distribution determines the expansion mode of the streamer, while the low capture energy of the solvated electron and local space charge accumulation contribute to the faster propagation of positive streamers at low voltage levels.
Article
Geosciences, Multidisciplinary
Andreas Johlander, Yuri V. V. Khotyaintsev, Andrew P. P. Dimmock, Daniel B. B. Graham, Ahmad Lalti
Summary: Electron heating at collisionless shocks is a result of adiabatic heating from large-scale electric and magnetic fields and non-adiabatic scattering from high-frequency fluctuations. This study uses data from the Magnetospheric Multiscale (MMS) spacecraft to investigate electron heating scales at Earth's quasi-perpendicular bow shock. By measuring the electron temperature gradient, the electron temperature profile inside the shock ramp is reconstructed, revealing that the temperature increase occurs on ion or sub-ion scales. Additionally, Liouville mapping is utilized to estimate the deHoffmann-Teller potential and electric field, showing that electron heating is highly non-adiabatic in high-Mach number shocks.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Thermodynamics
Yingkai Shen, Bin Zheng, Peng Sun, Youtang Wang, Tengfei Gao, Mingchao Wang, Chenglu Qi, Yongqi Liu
Summary: The study found that the distance between the double vacancy and the heating wall affects the heating characteristics of the particle pile, with the minimum heat flux and maximum thermal resistance occurring when the distance is equal to 1 times the particle size. Increasing relative distance between the double vacancy results in an increase in total heat flux on the heating wall and a decrease in thermal resistance of the particle reactor.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Construction & Building Technology
Xinmei Luo, Feng Ren, Hongqiang Ma, Yu Liu, Jiyue Wang, Yue Xie, Ruixiang Ding, Xiaofeng Jia
Summary: A heat transfer model is established for capillary radiant floor coupled with indoor particle diffusion, based on the discrete phase model (DPM) and Euler-Lagrange method. The distribution of temperature in the floor surface and the particles in the indoor room are analyzed. The concentration distribution characteristics of indoor particles in different sizes are further analyzed under the condition of different floor finishing layers. These results are significant for improving the design of capillary radiant floor heating system.
JOURNAL OF BUILDING ENGINEERING
(2023)
Article
Physics, Fluids & Plasmas
Li Wang, Peter Hartmann, Zoltan Donko, Yuan-Hong Song, Julian Schulze
Summary: This study reveals the effects of reactor geometry and electron-induced secondary electron emission coefficients on charged particle dynamics through PIC/MCC simulations, showing strong impacts on electron and ion energy distribution functions.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Physics, Fluids & Plasmas
Jing-Yu Sun, Quan-Zhi Zhang, Julian Schulze, You-Nian Wang
Summary: This study investigates the resonance heating mechanism between gyrating electrons and oscillating sheath induced by a small transverse magnetic field in low-pressure capacitively coupled plasmas. The electron kinetic behavior under resonant conditions is revealed through particle simulations. Numerical results demonstrate the relationship between magnetic field and driving frequency determines the resonance effect, and operating pressure, electrode gap, and driving voltage all strongly affect this electron resonance mechanism. The resonance effect is more pronounced at low pressure, large gap, and high voltage conditions.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2022)
Article
Physics, Fluids & Plasmas
M. Osca Engelbrecht, C. P. Ridgers, J. Dedrick, R. Boswell
Summary: High frequency capacitively coupled plasmas (CCPs) have numerous industrial applications, particularly in the semiconductor industry. Understanding the inductive heating effects within these plasmas is crucial for improving industrial applications. The development of a 1D particle-in-cell (PIC) code with a current heating model enables the simulation of inductive heating effects in high frequency CCPs, providing valuable insights for optimizing industrial plasma processes at the atomic level.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Applied
Tobias Gergs, Thomas Mussenbrock, Jan Trieschmann
Summary: In this study, an evolving surface state and defect structure are introduced to jointly describe sputtering and growth processes using physics-separating artificial neural networks. The plasma-surface interactions are described using hybrid reactive molecular dynamics/time-stamped force bias Monte Carlo simulations. It is demonstrated that considering the surface state and defect structure comprehensively describes the fundamental processes and a machine learning surrogate model is established with high physical fidelity.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Applied
P. Hartmann, I Korolov, J. Escandon-Lopez, W. van Gennip, K. Buskes, J. Schulze
Summary: Capacitively coupled plasmas are commonly used in many technological applications, requiring precise control of ion flux and energy distribution on boundary surfaces. The presence of dielectric wafers and targets can significantly affect the sheath electric field and lead to parasitic distortions of ion flux-energy distributions. We used particle in cell with Monte Carlo collisions simulations to study the operation, ion acceleration mechanisms, and distribution formation on dielectric wafers in argon gas discharges. The influence of low frequency pulsed voltage waveform on surface charging and ion flux-energy distribution was evaluated.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Applied
Yasunori Ohtsu, Kousuke Hara, Shoma Imoto, Julian Schulze, Takeshi Yasunaga, Yasuyuki Ikegami
Summary: In this study, the spatial structures of the ion flux to the substrate in an rf ring-shaped magnetized sputtering plasma with two facing cylindrical ZnO/Al2O3 targets were measured. The spatial distributions of the Hall parameter and Larmor radius of electrons and ions were also discussed using simulated values of the magnetic flux density. The ion flux magnitude varied with different argon gas pressures, and the radial profile showed a peak at the ring-shaped groove near the rf electrode.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Li Wang, Peter Hartmann, Zoltan Donko, Yuan-Hong Song, Julian Schulze
Summary: In this study, the effects of radial variations of electrode materials on plasma density and uniformity are investigated. By adjusting the surface coefficients on the electrodes, the radial plasma density profile can be finely tuned and plasma uniformity can be improved.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
S. Dujko, D. Bosnjakovic, M. Vass, P. Hartmann, I Korolov, N. R. Pinhao, D. Loffhagen, Z. Donko
Summary: We measured the electron swarm transport coefficients in CO at room temperature under time-of-flight conditions by scanning drift tube. The measurements were compared with modeling results and other experimental data. Monte Carlo simulations and solving the electron Boltzmann equation were used to obtain the modeling results. Generally, good agreement was found between the measured and calculated transport coefficients. A strategy to improve the cross-section set used to explain discrepancies at lower E/N values was proposed.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
Denis Eremin, Dennis Engel, Dennis Krueger, Sebastian Wilczek, Birk Berger, Moritz Oberberg, Christian Woelfel, Andrei Smolyakov, Jan Lunze, Peter Awakowicz, Julian Schulze, Ralf Peter Brinkmann
Summary: The electron dynamics and power absorption mechanisms in low pressure, radio-frequency driven, magnetically enhanced capacitively coupled plasmas are investigated. The study focuses on a geometrically asymmetric cylindrical magnetron with a nonuniform magnetic field in the axial direction and an electric field in the radial direction. Analytical and numerical models are used to analyze the dynamics, revealing that it significantly differs from an unmagnetized reference discharge. A new heating mechanism, termed the 'mu-mode', is proposed and found to be dominant in magnetized capacitively coupled discharges, differing from Ohmic heating.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
D. Eremin, E. Kemaneci, M. Matsukuma, T. Mussenbrock, R. P. Brinkmann
Summary: This study numerically investigates phenomena occurring in capacitively coupled plasmas with large electrodes and driven at very high frequencies. A novel energy- and charge-conserving particle-in-cell (PIC)/Monte Carlo code is utilized and validated with experimental data. It is found that the discharge produces radially uniform ion energy distribution functions, but ion fluxes exhibit strong radial nonuniformity, especially at increased pressure. The nonuniformity of ion flux is caused by the nonuniformity of the ionization source, which is influenced by mechanisms leading to the generation of energetic electrons.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
Zoltan Donko, Peter Hartmann, Ihor Korolov, David Schulenberg, Stefan Rohr, Shahid Rauf, Julian Schulze
Summary: The kinetics of excited atoms in a low-pressure argon capacitively coupled plasma source were studied using an extended PIC/MCC simulation code coupled with a diffusion-reaction-radiation code. The spatial density distribution of Ar atoms in the 1s(5) state within the electrode gap and the gas temperature were experimentally determined using tunable diode laser absorption spectroscopy. It was found that processes involving the excited states, particularly the four lower-lying 1s states, have significant effects on the ionization balance of the discharge.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
Yue Liu, Mate Vass, Gerrit Huebner, David Schulenberg, Torben Hemke, Lena Bischoff, Sascha Chur, David Steuer, Judith Golda, Marc Boeke, Julian Schulze, Ihor Korolov, Thomas Mussenbrock
Summary: The effects of structured electrode topologies on He/O-2 radio frequency micro-atmospheric pressure plasma jets driven at 13.56 MHz are investigated using 2D fluid simulations and experiments. The computational and experimental results show good qualitative agreement in terms of the dynamics of energetic electrons, helium metastable densities, and atomic oxygen densities. The presence of rectangular trenches in the electrodes causes a local increase in electron power absorption and subsequently increases the densities of metastable and atomic oxygen. Linear combinations of trenches along the gas flow direction result in an increase in atomic oxygen density, linearly dependent on the number of trenches. These findings can be explained by enhanced Ohmic electric fields inside the trenches due to low electron density and the electrode topology-induced current focusing effect.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Tobias Gergs, Thomas Mussenbrock, Jan Trieschmann
Summary: Plasma-surface interactions during AlN thin film sputter deposition were investigated using reactive molecular dynamics (RMD) methods. A revised COMB3 AlN potential was developed to accurately study these interactions. The revision involved tapering the Ziegler-Biersack-Littmark potential, implementing the QTE(+) variable charge model, and reworking the parameterization using a self-adaptive evolution strategy.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Fluids & Plasmas
Constantin Neuroth, Zaka-ul-islam Mujahid, Birk Berger, Christian Oberste-Beulmann, Timothy Oppotsch, Quan-Zhi Zhang, Martin Muhler, Thomas Mussenbrock, Ihor Korolov, Julian Schulze
Summary: Dielectric barrier discharges (DBDs) are promising tools for air pollution removal and gas conversion. Catalyst loading of dielectric pellets can improve such processes. Experimental investigation shows that different catalyst materials and locations have different effects on the discharge.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
K. Noesges, M. Klich, A. Derzsi, B. Horvath, J. Schulze, R. P. Brinkmann, T. Mussenbrock, S. Wilczek
Summary: In capacitively coupled radio frequency discharges, the interaction between plasma and surface boundaries is important for technological processes. Secondary electrons (SEs) significantly influence the discharge, but are often neglected. This study uses simulations to analyze and discuss the dynamics of different electron groups ('bulk-electrons', 'gamma-electrons', and 'delta-electrons'). It demonstrates that the electrode gap size can control the plasma density and explains the fundamental electron dynamics in different regimes.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
Han Luo, Jason Kenney, Shahid Rauf, Ihor Korolov, Julian Schulze
Summary: The plasma dynamics of a low pressure oxygen capacitively coupled plasma driven by dual frequencies is investigated experimentally and numerically. The study shows that the structure of the ion energy distribution function is influenced by the low-frequency voltage and pressure. A semi-analytical model is constructed to reveal the relationship between the sheath voltage and the IEDF.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)