Article
Physics, Multidisciplinary
Yuzhi Li, Bhuvana Srinivasan, Yanzeng Zhang, Xian-Zhu Tang
Summary: This study investigates the constraint of the Bohm criterion on the plasma exit flow speed. The analysis demonstrates that the Bohm speed is explicitly dependent on local plasma heat flux, temperature isotropization, and thermal force. Comparison with kinetic simulations confirms the accuracy of the Bohm speed over the plasma-sheath transition region where quasineutrality is weakly perturbed and the Bohm criterion applies.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Fluids & Plasmas
J. Adamek, F. J. Artola, A. Loarte, E. Matveeva, J. Cavalier, R. A. Pitts, R. Roccella, M. Lehnen, J. Havlicek, M. Hron, R. Panek
Summary: The presented experimental study in COMPASS tokamak shows that the current density during disruptions is limited by the ion particle flux. The study also finds that the halo current width increases with the plasma current, limiting the local forces.
Article
Chemistry, Multidisciplinary
Ziyang Zhao, Bo Bai, Kai Yuan, Rongxin Tang, Jiawei Xiong, Kaili Wang
Summary: Communication blackout caused by the plasma sheath surrounding hypersonic vehicles is a serious threat to their safety. This study investigates the impact of vehicle shapes on plasma sheaths and the radiation performance of THz antennae. The findings show that different vehicle shapes result in different plasma sheath structures and antenna performance. Blunt-coned plasma sheaths can refract antenna radiation direction, potentially leading to worsened communication quality.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Electrical & Electronic
Xin Ai, Qiuyue Nie, Zhonglin Zhang, Peiqi Chen, Changshi Yan, Guoqiang Wei
Summary: This article proposes an integrated model to study the transmission and scattering characteristics of electromagnetic (EM) waves in plasma sheaths for reentry vehicles. The key parameters and their distributions of the plasma sheath are investigated based on flying data. The results show that the multieffects of the plasma sheath can synergistically affect the transmission and scattering characteristics.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Physics, Fluids & Plasmas
A. Ahmed, S. Singha, S. Borthakur, N. K. Neog, T. K. Borthakur, J. Ghosh
Summary: Time-integrated spectroscopic measurements of argon plasma in a coaxial pulsed plasma accelerator revealed the temporal evolution of plasma stream characteristics, including changes in density, excitation temperature, and energy density over time. The study showed a decrease in plasma densities and excitation temperature, as well as a time-dependent decreasing trend in energy density, providing valuable insights for optimizing pulsed plasma accelerators.
PHYSICS OF PLASMAS
(2021)
Article
Thermodynamics
Bernard Parent, Prasanna T. Rajendran, Sergey O. Macheret, Justin Little, Robert W. Moses, Christopher O. Johnston, F. McNeil Cheatwood
Summary: The first study of coupling aerothermodynamics, magnetohydrodynamics (MHD), and plasma sheaths in Earth-entry flows is performed. The problem addresses a force-generating MHD patch between the stagnation point and the aft of a capsule entering Earth's atmosphere at Mach 34. The study considers the effects of electrode material on the MHD process, finding a significant increase in Lorentz forces and reduction in heat fluxes when using thoriated tungsten instead of graphite.
JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER
(2023)
Article
Physics, Fluids & Plasmas
P. Tolias, M. Komm, S. Ratynskaia, A. Podolnik
Summary: Accurate and efficient modeling of macroscopic melt motion induced by fast transients requires precise description of the emitted current density that escapes to the pre-sheath. By employing systematic particle-in-cell simulations and a comprehensive analytical electron emission model, a highly accurate semi-empirical treatment of the escaping electron current has been achieved.
Review
Engineering, Environmental
Lu Liu, Guangcai Shao, Chuanlong Ma, Anton Nikiforov, Nathalie De Geyter, Rino Morent
Summary: Plasma-catalysis is considered as a promising method for decomposing hazardous VOCs, and extensive experimental and modeling studies have been conducted to understand its fundamental mechanisms. However, there is a lack of literature on summarized modeling methodologies. This short review provides a comprehensive overview of modeling methodologies in plasma-catalysis, classifies and summarizes the modeling methods of VOCs decomposition, critically examines the roles of plasma and plasma-catalyst interactions, and offers perspectives for future research directions. The aim of this review is to stimulate the further development of plasma-catalysis for VOCs decomposition with advanced modeling methods in both fundamental studies and practical applications.
JOURNAL OF HAZARDOUS MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Bo Bai, Ziyang Zhao, Kai Yuan, Rongxin Tang, Xiaohua Deng, Mingyang Mao, Jiawei Xiong, Kaili Wang
Summary: This study investigates the communication blackout problem of hypersonic vehicles and explores potential solutions. It is found that despite the potential mitigation effect of an external magnetic field on the attenuation of millimeter waves in plasma sheaths, collision remains the main dissipation mechanism. Furthermore, the effect of a dipole magnetic field in a blunt-coned plasma sheath is weaker compared to a uniform magnetic field.
APPLIED SCIENCES-BASEL
(2022)
Article
Physics, Fluids & Plasmas
Toshisato Ono, Uwe R. Kortshagen, Christopher J. Hogan
Summary: This study used laser light scattering to investigate trapping of submicrometer metal oxide particles near the upper electrode of a CCP reactor. The trapping location moved further from the electrode with decreased reactor pressure, and particle trapping appeared to be influenced by the material dielectric constant. Further research is needed to understand how particle material properties affect forces on particles in plasma and the role of ion drag forces in trapping.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Ricardo A. S. Silva, Nenad Bundaleski, Orlando M. N. D. Teodoro
Summary: Hot cathode ionisation gauges are reliable pressure measurement devices for high and ultra-high vacuum measurement, but with low accuracy. This study simulated the performance of Bayard-Alpert and extractor gauges under different magnetic field conditions and compared with previous experimental results. Both gauges showed sensitivity to low intensity magnetic fields, but the extractor gauge exhibited better stability due to its ring-shaped cathode.
Article
Multidisciplinary Sciences
Yongming Yang, Xiwen Li, Mengke Sun, Yang Ju
Summary: The influence of porous and double-layer structures on the deformation failure of cement sheaths under hydraulic pressure was studied. The research revealed the effects of these structures on breakdown pressure, plastic failure zone, radial deformation, and stress distribution, providing insights into failure modes, failure paths, and interactions with metal casings.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Fluids & Plasmas
J. Moreno, A. Khodaee, D. Okerstrom, M. P. Bradley, L. Couedel
Summary: The study investigates the perturbations induced by high-voltage pulses on plasma parameters in an argon inductively coupled radio frequency plasma device, where fluctuations in electron density, temperature, and plasma potential are observed following negative polarity pulses. The perturbations are significantly dampened at higher power and closer to the plasma RF coil, with amplitudes increasing with pulse amplitude and secondary electron yield from the target material. The underlying mechanism of the perturbation is suggested to be plasma heating driven by damping of a beam-plasma instability due to a beam of secondary electrons emitted by the target.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
Pierre S. Houdayer, Daniel R. Reese, Marie-Jo Goupil, Yveline Lebreton
Summary: The authors propose an analytical approximation for the first adiabatic exponent Gamma(1) by thermodynamically treating the ionisation region. It is found that the induced stellar structure only depends on three parameters, including the surface helium abundance Y-s and the electron degeneracy psi(CZ) in the convective region. The modeling work conducted allows for a wide variety of structures to be described and suggests that the structure is more dependent on the electron degeneracy in the convection zone and the position of the ionisation region rather than the amount of helium itself.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Pierre S. Houdayer, Daniel R. Reese, Marie-Jo Goupil
Summary: This study explores the issue of helium-mass degeneracy in determining the properties of solar-like oscillating stars. By exploiting the structural variation in the ionisation zones, an independent estimate of helium content can be obtained to overcome this degeneracy. The current modelling approach faces challenges and requires calibration using realistic stellar models. Through a thermodynamic treatment of the ionisation region, an analytical approximation is presented, which allows for a wide variety of structures to be described.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Physics, Applied
Tatsuru Shirafujil, Kazuki Denpoh
JAPANESE JOURNAL OF APPLIED PHYSICS
(2018)
Article
Materials Science, Coatings & Films
Shinya Iwashita, Kazuki Denpoh, Takamichi Kikuchi, Yusuke Suzuki, Yuichiro Wagatsuma, Toshio Hasegawa, Tsuyoshi Moriya
SURFACE & COATINGS TECHNOLOGY
(2018)
Article
Materials Science, Multidisciplinary
Shinya Iwashita, Kazuki Denpoh, Munehito Kagaya, Takamichi Kikuchi, Naotaka Noro, Toshio Hasegawa, Tsuyoshi Moriya, Akira Uedono
Article
Physics, Applied
Kazuki Denpoh, Tatsuru Shirafuji
JAPANESE JOURNAL OF APPLIED PHYSICS
(2009)
Article
Physics, Applied
Kazuki Denpoh, Tatsuru Shirafuji
JAPANESE JOURNAL OF APPLIED PHYSICS
(2010)
Article
Physics, Applied
Kazuki Denpoh, Tatsuru Shirafuji
JAPANESE JOURNAL OF APPLIED PHYSICS
(2011)
Article
Physics, Applied
Kazuki Denpoh
JAPANESE JOURNAL OF APPLIED PHYSICS
(2012)
Article
Physics, Applied
Kazuki Denpoh
JAPANESE JOURNAL OF APPLIED PHYSICS
(2014)
Article
Physics, Applied
K. Denpoh
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2009)
Article
Materials Science, Coatings & Films
P. L. G. Ventzek, K. Denpoh
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2009)
Article
Physics, Applied
Hu Li, Hisashi Higuchi, Satoru Kawaguchi, Kohki Satoh, Kazuki Denpoh
JAPANESE JOURNAL OF APPLIED PHYSICS
(2019)
Article
Physics, Applied
Satoru Kawaguchi, Hisashi Higuchi, Hu Li, Kazuki Denpoh, Kazuhiro Takahashi, Kohki Satoh
JAPANESE JOURNAL OF APPLIED PHYSICS
(2019)
Article
Physics, Applied
Kazuki Denpoh, Paul Moroz, Taiki Kato, Masaaki Matsukuma
JAPANESE JOURNAL OF APPLIED PHYSICS
(2020)
Article
Materials Science, Coatings & Films
Kazuki Denpoh, Kenichi Nanbu
Summary: The ion-molecule collision model DNT+ incorporates both short-range and long-range charge exchanges between ions and molecules, providing comprehensive cross section data for plasma simulations and facilitating the generation of preliminary data prior to experiments.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2022)
Article
Engineering, Electrical & Electronic
Hu Li, Koichi Ishii, Shun Sasaki, Mao Kamiyama, Akinori Oda, Kazuki Denpoh
Summary: This study investigates the mechanisms of plasma-enhanced chemical vapor deposition using tetraethoxysilane (TEOS)-based plasma. Experimental measurements show that more TEOS fragments are generated in helium/TEOS plasma than in argon/TEOS plasma. Plasma simulation reveals that helium/TEOS plasma has a higher electron temperature, enhancing dissociation reactions. The spatial distribution of TEOS fragments increases as the O-2 ratio increases, but excessive O-2 flow decreases the number of signals.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)