Article
Physics, Fluids & Plasmas
G. F. Torija Daza, J. M. Reynolds-Barredo, R. Sanchez, A. Loarte, G. Huijsmans
Summary: We present an efficient iterative, free-plasma-boundary solver for the Grad-Shafranov-Bernoulli system of equations, which describes the ideal MHD equilibrium of a toroidally axisymmetric plasma with flow. The code allows quantification of the influence of plasma flows on important features of plasma equilibrium.
Article
Physics, Fluids & Plasmas
V Ostuni, J. F. Artaud, G. Giruzzi, E. Joffrin, H. Heumann, H. Urano
Summary: The fast integrated tokamak modeling tool METIS is coupled with the quasi-static free-boundary magnetic equilibrium code FEEQS to simulate a full tokamak discharge scenario design. The outputs generated by the first code are used iteratively by the second code to compute the poloidal field coils currents needed, making the approach faster and complementary to full simulators. The results are benchmarked with TOSCA code data and illustrated through the optimization of a reference scenario of the JT-60SA tokamak.
Article
Computer Science, Interdisciplinary Applications
K. S. Han, B. H. Park, A. Y. Aydemir, M. H. Woo
Summary: A novel mapping technique is used to solve the free-boundary equilibrium problem for tokamaks, simplifying the calculation process. Numerical solutions validate the accuracy of the method, and a hybrid scheme demonstrates faster computation speed.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
Lu Yuan, Di Hu
Summary: In this study, a Grad-Shafranov-like equation is derived to solve for the axisymmetric drift surfaces of the runaway electrons driven by ion pressure, and the equation is numerically solved with simple rectangular wall using ITER-like and MAST-like geometric parameters. It is found that the runaway electrons can be well confined even in regions with open field lines. The change of the runaway electron parallel momentum results in a horizontal current center displacement without affecting the total current or the external field. The distribution of the runaway current density profile affects the susceptibility of this displacement, with flatter profiles resulting in larger displacement under the same momentum change. Lastly, with up-down asymmetry in the external poloidal field, the displacement is accompanied by a vertical displacement of the runaway electron current, which is more pronounced in smaller, compact devices and weaker poloidal field cases.
Article
Physics, Fluids & Plasmas
Xinhao Jiang, Youwen Sun
Summary: This paper proposes different approaches for dealing with singularities in solving the nonlinear Grad-Shafranov equation in flux coordinates and presents a novel coordinate transform technique to remove the singularity at the magnetic axis. It also introduces a method to resolve the issue of the separatrix in a flux coordinate system and develops a new equilibrium solver based on flux coordinates.
PLASMA SCIENCE & TECHNOLOGY
(2022)
Article
Mathematics
Yuri Mitrishkin, Evgeniia Pavlova, Mikhail Khlebnikov
Summary: This paper focuses on the synthesis, comparison, and optimization of robust LMI-control systems for the vertical plasma position in a D-shaped tokamak. It explores the possibilities of utilizing LMI robust control systems, using a unique unstable first-order plasma model, to reject disturbances and reference signals. The main achievement of this work is the optimization of robust control systems for an unstable plant with uncertain disturbances using a set of LMI synthesis approaches.
Article
Nuclear Science & Technology
Na-Na Bao, Yao Huang, Bing-Jia Xiao, Qi-Ping Yuan, Zheng-Ping Luo, Yue-Hang Wang, Shu-Liang Chen
Summary: This paper proposes a new gamma control method to regulate the vertical growth rate in real-time feedback control, successfully applied to the experimental advanced superconducting tokamak (EAST), demonstrating its capability to keep the plasma away from its unstable boundary.
NUCLEAR SCIENCE AND TECHNIQUES
(2021)
Article
Nuclear Science & Technology
H. Anand, O. Bardsley, D. Humphreys, M. Lennholm, A. Welander, Z. Xing, J. Barr, M. Walker, J. Mitchell, H. Meyer
Summary: The performance requirements and design solutions for the magnetic controller of the Spherical Tokamak for Energy Production (STEP) aim to achieve equilibrium and scenario trajectories, maintain steady plasma vertical stabilization and shape control, and avoid contact with plasma-facing components (PFCs). Various axisymmetric magnetic control schemes, including vertical stabilization, plasma current control, plasma shape control, and poloidal field coil current control, are being developed using the TokSys control analysis tools for the STEP Prototype Reactor (SPR) concept. Simulation results show that the control performance and controllability of the axisymmetric control systems are consistent with the scenario requirements under reasonable assumptions of power supply and sensor performance.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Computer Science, Interdisciplinary Applications
Emily Bourne, Philippe Leleux, Katharina Kormann, Carola Kruse, Virginie Grandgirard, Yaman Guclu, Martin J. Kuhn, Ulrich Rude, Eric Sonnendrucker, Edoardo Zoni
Summary: This paper compares three finely tuned solvers for solving Poisson-like equations on complex geometries. The solvers are evaluated based on their solution accuracy, computational efficiency, and practical implementation aspects. The Spline FEM solver is shown to be the most accurate, the GMGPolar solver uses the least memory, and the Embedded Boundary solver is the fastest in most cases. All three solvers can handle realistic non-analytical geometries.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Mathematics, Applied
Cedric Boulbe, Blaise Faugeras, Guillaume Gros, Francesca Rapetti
Summary: This paper investigates the axisymmetric equilibrium problem of a hot plasma in a tokamak. A non-overlapping mortar element approach is adopted, which couples C0 piece-wise linear Lagrange finite elements in a region without plasma and C1 piece-wise cubic reduced Hsieh-Clough-Tocher finite elements elsewhere, to approximate the magnetic flux field on a triangular mesh of the poloidal tokamak section. The inclusion of ferromagnetic parts is simplified by assuming their axisymmetric fit, and a new formulation of the Newton algorithm for problem solution is stated for both static and quasi-static evolution cases.
JOURNAL OF SCIENTIFIC COMPUTING
(2023)
Article
Mathematics
Vladimir D. Pustovitov, Nikolay V. Chukashev
Summary: This article considers the dynamic problem of plasma equilibrium in a tokamak, with a focus on the electromagnetic reaction of the vacuum vessel resistive wall. The induced currents in the wall affect the external magnetic field, which in turn determines the plasma shape and position. The simultaneous consideration of these factors presents a challenge in the description.
Article
Computer Science, Interdisciplinary Applications
M. Giacomin, P. Ricci, A. Coroado, G. Fourestey, D. Galassi, E. Lanti, D. Mancini, N. Richart, L. N. Stenger, N. Varini
Summary: This paper describes a new version of the GBS code that extends the simulation domain to encompass the entire plasma volume and introduces a toroidal coordinate system for increased flexibility. A new iterative solver for Poisson and Ampere equations is implemented, leading to faster code execution. The self-consistent kinetic neutral model is optimized for different magnetic configurations. The numerical implementation is verified using the method of manufactured solutions. A simulation of a TCV tokamak discharge is presented as an example.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Ali Elarif, Blaise Faugeras, Francesca Rapetti
Summary: This study presents a numerical simulation technique that combines finite element method and triangular mesh to improve the accuracy of the equilibrium of the plasma in a tokamak and its coupling with resistive diffusion. The method achieves higher order regularity in the plasma-covered area while maintaining accuracy in meshing the geometric details in the rest of the computational domain.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Instruments & Instrumentation
H. Lian, H. Q. Liu, D. L. Brower, W. X. Ding, Y. Huang, S. X. Wang, W. M. Li, Y. Q. Chu, R. J. Zhu, Y. X. Jie
Summary: Vertical position stability is crucial for safe and reliable plasma operation in long-pulse fusion devices. This paper compares the non-inductively determined vertical position achieved by line-integrated interferometer and polarimeter measurements with the inductive flux loop method. The results show that the non-inductive measurement is more robust than flux loops after a certain time and propose using the non-inductive system for real-time vertical position control in the next experimental campaign.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Physics, Fluids & Plasmas
D. Kiramov, B. N. Breizman
Summary: This paper examines the vertical plasma motion resulting from plasma current decay during a disruption event. The presented filament-based model describes the motion in the ideal wall limit as a slow evolution of the plasma equilibrium. The equilibrium undergoes a pitchfork bifurcation when the decaying plasma current reaches a critical value determined by the external magnetic field. This bifurcation impacts the disruption-induced mechanical loads on the first wall.
PHYSICS OF PLASMAS
(2022)
Article
Energy & Fuels
Antonio Castaldo, Raffaele Albanese, Roberto Ambrosino, Flavio Crisanti
Summary: This paper presents important research in the field of nuclear fusion regarding the power exhaust problem. The study includes detailed descriptions and demonstrations of plasma scenarios for standard and alternative configurations in the Divertor Tokamak Test (DTT) tokamak, showcasing the flexibility of the machine.
Article
Nuclear Science & Technology
Francesco Maviglia, Christian Bachmann, Gianfranco Federici, Thomas Franke, Mattia Siccinio, Raffaele Albanese, Roberto Ambrosino, Wayne Arter, Roberto Bonifetto, Giuseppe Calabro, Riccardo De Luca, Luigi E. Di Grazia, Emiliano Fable, Pierluigi Fanelli, Alessandra Fanni, Mehdi Firdaouss, Jonathan Gerardin, Riccardo Lombroni, Massimiliano Mattei, Matteo Moscheni, William Morris, Gabriella Pautasso, Sergey Pestchanyi, Giuseppe Ramogida, Maria Lorena Richiusa, Giuliana Sias, Fabio Subba, Fabio Villone, Jeong-Ha You, Zsolt Vizvary
Summary: This work presents an integrated strategy to protect the EU-DEMO first wall (FW) from planned and unplanned plasma transients using discrete limiters. The strategy aims to ensure the integrity of the FW by evaluating design changes, performing plasma simulations, and designing discrete limiters. The paper also discusses the preliminary analysis of heat loads on the Plasma Facing Components (PFC) and includes comments from a review panel and additional studies triggered by their feedback.
FUSION ENGINEERING AND DESIGN
(2022)
Editorial Material
Nuclear Science & Technology
Francesco Maviglia, Christian Bachmann, Gianfranco Federici, Thomas Franke, Mattia Siccinio, Raffaele Albanese, Roberto Ambrosino, Wayne Arter, Roberto Bonifetto, Giuseppe Calabro, Riccardo De Luca, Luigi E. Di Grazia, Emiliano Fable, Pierluigi Fanelli, Alessandra Fanni, Mehdi Firdaouss, Jonathan Gerardin, Riccardo Lombroni, Massimiliano Mattei, Matteo Moscheni, William Morris, Gabriella Pautasso, Sergey Pestchanyi, Giuseppe Ramogida, Maria Lorena Richiusa, Giuliana Sias, Fabio Subba, Fabio Villone, Jeong-Ha You, Zsolt Vizvary
FUSION ENGINEERING AND DESIGN
(2022)
Article
Physics, Fluids & Plasmas
Yao Huang, Adriano Mele, Zhengping Luo, Massimiliano Mattei, Alfredo Pironti, Bingjia Xiao, Qiping Yuan
Summary: This article discusses the integration of a Kalman filter in the P-EFIT equilibrium reconstruction code for estimating currents induced in the passive structures of a tokamak. The observer, integrated into the equilibrium reconstruction, uses estimates from the Kalman filter to refine the solution. The algorithm is tested on ITER tokamak, evaluating its performance in terms of convergence metrics, eddy currents estimation accuracy, and reconstruction of plasma-related quantities.
Article
Energy & Fuels
Raffaele Albanese, Andrea Gaetano Chiariello, Raffaele Fresa, Antonio Iaiunese, Raffaele Martone, Pasquale Zumbolo
Summary: This paper explores the suitability of Chebyshev polynomials for magnetic field-line tracking and discusses the conditions in which they are most effective, while also quantifying the impact of parallel computing in approximation procedures.
Article
Engineering, Aerospace
Luciano Blasi, Egidio D'Amato, Massimiliano Mattei, Immacolata Notaro
Summary: In this article, an optimal path search methodology is presented for UAVs flying in 3-D environments, considering obstacles and flight dynamics constraints. The essential visibility graph (EVG) is extended to the 3-D case using layered parallel planar layers. The resulting layered EVG (LEVG) is based on an efficient branching algorithm, resulting in a reduced computational burden.
IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS
(2023)
Article
Nuclear Science & Technology
R. Ambrosino, R. Albanese, E. Acampora, A. Castaldo, F. Crisanti, R. Iervolino, A. Lampasi
Summary: For the next generation fusion devices, in-vessel coils are crucial for handling elongated plasmas and alternative configurations, but they are highly sensitive to the vertical unstable mode. A pair of equatorial in-vessel coils connected in anti-series can effectively address the vertical control problem. Independent equatorial coils can also provide fast radial control to protect plasma facing components during fast plasma transients. However, they are vulnerable to induced current during disruptive events. In this paper, a solution for the conceptual design of in-vessel equatorial coils is presented, which ensures control performance and robustness in case of disruption, as demonstrated by simulations.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Operations Research & Management Science
Luigi Emanuel di Grazia, Domenico Frattolillo, Gianmaria De Tommasi, Massimiliano Mattei
Summary: Tokamaks are considered the most promising devices for achieving nuclear fusion energy production on Earth. In this paper, three different algorithms are proposed to address the problem of avoiding saturation of currents in large tokamaks, particularly for the DEMO fusion power plant. The performance of these algorithms is evaluated using challenging operation scenarios for the DEMO reactor, and the computational burden required for real-time implementation is also assessed.
JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS
(2023)
Article
Engineering, Aerospace
Egidio D'Amato, Immacolata Notaro, Giulia Panico, Luciano Blasi, Massimiliano Mattei, Alessia Nocerino
Summary: This paper deals with the design of a guidance and control algorithm for the re-entry of a capsule with a deployable aero-brake. It utilizes a trajectory optimization model to design the reference re-entry path and utilizes a Nonlinear Model Predictive Control (NMPC) to modulate the opening of the aero-brake in order to follow the planned trajectory towards the target.
Article
Remote Sensing
Salvatore Rosario Bassolillo, Egidio D'Amato, Immacolata Notaro, Gennaro Ariante, Giuseppe Del Core, Massimiliano Mattei
Summary: A sensor fusion algorithm based on Kalman filtering is proposed in this paper to improve the navigation accuracy of unmanned aerial vehicles (UAVs) in indoor or GPS-denied environments. The algorithm utilizes a low-cost navigation platform and shows high precision and robustness in numerical tests. It is ready to be implemented on low-cost platforms.
Article
Remote Sensing
Salvatore Rosario Bassolillo, Luciano Blasi, Egidio D'Amato, Massimiliano Mattei, Immacolata Notaro
Summary: This paper discusses the design of a guidance control system for a swarm of unmanned aerial systems flying at a given altitude, addressing flight formation requirements. By comparing different guidance algorithms, the effectiveness of the proposed guidance schemes is proven.
Article
Automation & Control Systems
G. Tartaglione, R. Ambrosino, M. Ariola
Summary: This letter presents new sufficient conditions for the annular stochastic finite-time stability of a class of stochastic linear time-varying systems, using time-varying piecewise quadratic Lyapunov functions. The proposed approach extends the class of consider domains and shows less conservatism compared to previous conditions.
IEEE CONTROL SYSTEMS LETTERS
(2022)
