Article
Physics, Fluids & Plasmas
R. Samulyak, S. Yuan, N. Naitlho, P. B. Parks
Summary: A 3D numerical model based on the Lagrangian particle method has been developed for pellet and shattered pellet injection ablation in tokamaks. The model shows good agreement with theory for spherically symmetric ablation flows and demonstrates the influence of grad-B drift on ablation rates and properties of ablation clouds. Smaller reductions of ablation rates in magnetic fields compared to axially symmetric simulations have been attributed to the absence of confinement by grad-B drift.
Article
Physics, Fluids & Plasmas
R. Ramasamy, M. Hoelzl, S. Henneberg, E. Strumberger, K. Lackner, S. Guenter
Summary: The equilibrium code VMEC is used to study external kinks in low beta tokamaks and l = 2 stellarators, and its applicability in modeling nonlinear MHD effects is explored. The study shows the limitations of free boundary VMEC computations and the need for additional constraints to obtain accurate results. The dependence of the kink mode on the external rotational transform and field periodicity is investigated, but contradictory results are obtained. The accuracy of VMEC solutions is demonstrated by comparing with the initial value code JOREK.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Fluids & Plasmas
Eleonore Geulin, Bernard Pegourie
Summary: This paper discusses the principles and mechanisms of fueling in a fusion reactor. Pellet injection is considered the best method, using ablation and drift processes to introduce fuel into the plasma. The effectiveness of the method depends on plasma characteristics and magnetic field configuration.
PLASMA AND FUSION RESEARCH
(2022)
Article
Physics, Fluids & Plasmas
Jie Zhang, Joseph McClenaghan, Paul Parks, Lang Lao, Wen Wu
Summary: A two-dimensional Gaussian deposition model is developed in this study to calculate the initial pellet deposition density after pellet ablation, which can solve the singularity problem encountered by the conventional point deposition model. The model predicts that the initial pellet deposition density strongly depends on the ablation cloud radius and the form of radial particle distribution. By introducing the backward difference B-drift with estimated drift displacement, the model can provide a fast evaluation of pellet deposition density compared to the predictive HPI2 code.
Article
Astronomy & Astrophysics
Michaela Brchnelova, Blazej Kuzma, Barbara Perri, Andrea Lani, Stefaan Poedts
Summary: Global coronal models are increasingly used for forecasting solar weather, relying on accurate and efficient computations. However, achieving these results requires intricate numerical adjustments, such as formulating inner and outer boundary conditions. By omitting the electric field in ideal MHD and focusing on techniques like enforcing parallelism between magnetic field and velocity, improvements in accuracy can be achieved.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2022)
Article
Mechanics
Yong Han, Ling Zhou, Ling Bai, Weidong Shi, Ramesh Agarwal
Summary: Turbulence modeling is essential for accurate prediction of turbulent fluid motion, and a new one-equation Wray-Agarwal (WA) turbulence model has been developed to improve predictions for turbulent flows with large separation and curvature. Comparison with other commonly used turbulence models shows that the WA model gives the highest accuracy in predicting the complex three-dimensional turbulent characteristics of flow with large curvature in a U-bend.
Article
Physics, Fluids & Plasmas
R. Calado, F. Nabais, S. E. Sharapov, Joao P. S. Bizarro
Summary: This study investigates the coupling between upwards frequency sweeping modes and tornado modes observed in JET sawtoothing discharges. The frequency sweeping modes are identified as near-axis Alfven cascade eigenmodes, which are associated with a very flat but monotonic q-profile near the magnetic axis. The frequency evolution of the modes during a gradual decrease of the q-profile is reproduced numerically, and the transition from cascade modes to tornado modes is demonstrated. Based on this result, a novel MHD spectroscopy technique is proposed to track the evolution of the q-profile in the post sawtooth crash regime using tornado mode tips as MHD markers. Calculations also show the ions transferring their energy to the modes, contributing to the mode drive.
Article
Physics, Multidisciplinary
De-Qi Wen, Peng Zhang, Janez Krek, Yangyang Fu, John P. Verboncoeur
Summary: This Letter reports the novel physics of higher harmonic (HH) generation of the normal electric field near a dielectric surface in multipactor induced plasma ionization breakdown, as determined by kinetic particle-in-cell simulations. The observed HH frequency is around ten times the fundamental rf driving frequency, but lower than the electron plasma frequency. A constructed theory indicates that stream plasma interaction-induced instability is the mechanism of HH generation in the collisional regime. The HH frequency and its corresponding growth rate of the HH oscillation amplitude from the theory are in good agreement with kinetic particle-in-cell simulations.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Fluids & Plasmas
D. Hu, C. Liu
Summary: This article investigates the thermalization dynamics and overall impact of hot-electron collision in the process of shattered pellet injection, and finds that the hot-tail effect can enhance the assimilation and shallow penetration, which is of great significance for the effectiveness of shattered pellet injection as a disruption mitigation system.
Review
Cardiac & Cardiovascular Systems
Teiichi Yamane
Summary: Catheter ablation has become a common treatment for atrial fibrillation, aiming to eliminate symptoms and improve quality of life. Recent studies have sought to determine its impact on patient prognosis, but clear evidence of long-term improvement has not been found. However, catheter ablation is widely performed for asymptomatic atrial fibrillation with similar effectiveness to symptomatic cases.
JOURNAL OF CARDIOLOGY
(2022)
Article
Chemistry, Physical
Toshifumi Mori, Norio Yoshida
Summary: The interaction between ATP and disordered proteins plays a crucial role in protein aggregate dissolution and liquid-liquid phase separation. Different water models impact the ATP properties in high concentration, with TIP3P water model leading to excessive ATP aggregation and TIP4P-D and OPC water models promoting ATP-protein interactions.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Chenyuan Li, Darshan G. Joshi, Subir Sachdev
Summary: Anomalous metals have been observed in experiments on disordered two-dimensional systems proximate to superconductivity. A proposed dynamical mean-field model provides insights into the behavior of anomalous metals, showing evidence of critical anomalous phases or points between superconducting and disordered Fermi liquid phases. The large M limit describes the anomalous metal by fractionalization of electrons into various partons, forming critical non-Fermi liquids.
Article
Chemistry, Physical
Min Li, John Zeng Hui Zhang
Summary: The study developed a coarse-grained water model based on cluster-level electrostatic dipoles and refined it using experimental data. The new model accurately predicts water properties and can be used for building efficient multi-resolution water models.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Optics
Giulio Gasbarri, Alessio Belenchia, Mauro Paternostro, Hendrik Ulbricht
Summary: Near-field interferometry with large dielectric nanoparticles offers a new way to test fundamental modifications of standard quantum mechanics, showcasing the capabilities of this platform in setting stringent bounds on collapse model parameters and highlighting future prospects for these experiments.
Article
Computer Science, Interdisciplinary Applications
Ana Gonzalez-Suarez, Ramiro M. Irastorza, Stuart Deane, Barry O'Brien, Martin O'Halloran, Adnan Elahi
Summary: This study aimed to assess the electric field distribution in the heart and its surroundings during epicardial monopolar PEF ablation. The results showed that the electric field was mainly limited to the target area in the heart, and negligible in adjacent organs. The limited-domain model provided similar results to the full torso model in evaluating the electric field distribution.
COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE
(2022)
Article
Computer Science, Interdisciplinary Applications
Xingyu Wang, Roman Samulyak, Xiangmin Jiao, Kwangmin Yu
JOURNAL OF COMPUTATIONAL PHYSICS
(2016)
Article
Computer Science, Interdisciplinary Applications
Roman Samulyak, Xingyu Wang, Hsin-Chiang Chen
JOURNAL OF COMPUTATIONAL PHYSICS
(2018)
Article
Instruments & Instrumentation
K. Yu, R. Samulyak, K. Yonehara, B. Freemire
JOURNAL OF INSTRUMENTATION
(2018)
Article
Physics, Nuclear
Jun Ma, Xingyu Wang, Gang Wang, Kwangmin Yu, Roman Samulyak, Vladimir Litvinenko
PHYSICAL REVIEW ACCELERATORS AND BEAMS
(2018)
Article
Physics, Fluids & Plasmas
Wen Shih, Roman Samulyak, Scott C. Hsu, Samuel J. Langendorf, Kevin C. Yates, Y. C. Francis Thio
PHYSICS OF PLASMAS
(2019)
Article
Nuclear Science & Technology
Y. C. Francis Thio, Scott C. Hsu, F. Douglas Witherspoon, Edward Cruz, Andrew Case, Samuel Langendorf, Kevin Yates, John Dunn, Jason Cassibry, Roman Samulyak, Peter Stoltz, Samuel J. Brockington, Ajoke Williams, Marco Luna, Robert Becker, Adam Cook
FUSION SCIENCE AND TECHNOLOGY
(2019)
Article
Physics, Fluids & Plasmas
Prabhat Kumar, Kwangmin Yu, Rafal Zgadzaj, Ligia Diana Amorim, M. C. Downer, James Welch, Vladimir N. Litvinenko, Navid Vafaei-Najafabadi, Roman Samulyak
PHYSICS OF PLASMAS
(2019)
Article
Physics, Fluids & Plasmas
R. Samulyak, S. Yuan, N. Naitlho, P. B. Parks
Summary: A 3D numerical model based on the Lagrangian particle method has been developed for pellet and shattered pellet injection ablation in tokamaks. The model shows good agreement with theory for spherically symmetric ablation flows and demonstrates the influence of grad-B drift on ablation rates and properties of ablation clouds. Smaller reductions of ablation rates in magnetic fields compared to axially symmetric simulations have been attributed to the absence of confinement by grad-B drift.
Article
Physics, Fluids & Plasmas
Prabhat Kumar, Kwangmin Yu, Rafal Zgadzaj, Michael Downer, Irina Petrushina, Roman Samulyak, Vladimir Litvinenko, Navid Vafaei-Najafabadi
Summary: In this study, long wavelength infrared laser-driven plasma wakefield accelerators were investigated in both the self-modulated laser wakefield acceleration (SM-LWFA) and blowout regimes using 3D particle-in-cell simulations. The results show that self-injection occurs with wave breaking in the SM-LWFA regime, but not in the blowout regime under the simulation conditions. The wave breaking process in the SM-LWFA regime intensifies with higher laser power and plasma density, but is suppressed at low plasma densities.
PHYSICS OF PLASMAS
(2021)
Article
Computer Science, Interdisciplinary Applications
Kwangmin Yu, Prabhat Kumar, Shaohua Yuan, Aiqi Cheng, Roman Samulyak
Summary: This article presents a parallel, relativistic, three-dimensional particle-in-cell code SPACE, with efficient algorithms and adaptive methods for simulating electromagnetic fields, particle beams, and plasmas, suitable for accelerator science and engineering problems.
COMPUTER PHYSICS COMMUNICATIONS
(2022)
Article
Physics, Fluids & Plasmas
E. M. Hollmann, N. Naitlho, S. Yuan, R. Samulyak, P. Parks, D. Shiraki, J. Herfindal, C. Marini
Summary: In this study, small neon pellet fragments were fired into plasma to investigate the photon efficiency. The modeling analysis showed that the efficiency increases with the ablation rate, indicating the importance of non-equilibrium kinetics.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
Shaohua Yuan, Nizar Naitlho, Roman Samulyak, Bernard Pegourie, Eric Nardon, Eric Hollmann, Paul Parks, Michael Lehnen
Summary: Numerical studies using a time-dependent pellet ablation code have explored the ablation of pellets and shattered pellet injection fragments into a runaway electron beam in ITER. The study revealed that the penetration depth of the ablation clouds is approximately 50 cm.
PHYSICS OF PLASMAS
(2022)
Article
Mechanics
Shaohua Yuan, Mario Zepeda Aguilar, Nizar Naitlho, Roman Samulyak
Summary: The study developed, verified, and implemented massively-parallel, distributed-memory algorithms for the Lagrangian particle hydrodynamic method. The parallel algorithms include a particle management module based on the p4est library. The code has been applied to various fundamental science and applied problems, including the injection of impurities into thermonuclear fusion devices and the simulation of supersonic hydrogen jets for laser-plasma wakefield acceleration research.
MECHANICS RESEARCH COMMUNICATIONS
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
Shih-Chung Hsu, Hsin-Hui Huang, Chung-Lin Huang
2017 FIRST IEEE INTERNATIONAL CONFERENCE ON ROBOTIC COMPUTING (IRC)
(2017)