2022 Review of Data-Driven Plasma Science

Data-driven science and technology offer transformative tools and methods to science. This review article highlights the latest development and progress in the interdisciplinary field of data-driven plasma science (DDPS), i.e., plasma science whose progress is driven strongly by data and data analyses. Plasma is considered to be the most ubiquitous form of observable matter in the universe. Data associated with plasmas can, therefore, cover extremely large spatial and temporal scales, and often provide essential information for other scientific disciplines. Thanks to the latest technological developments, plasma experiments, observations, and computation now produce a large amount of data that can no longer be analyzed or interpreted manually. This trend now necessitates a highly sophisticated use of high-performance computers for data analyses, making artificial intelligence and machine learning vital components of DDPS. This article contains seven primary sections, in addition to the introduction and summary. Following an overview of fundamental data-driven science, five other sections cover widely studied topics of plasma science and technologies, i.e., basic plasma physics and laboratory experiments, magnetic confinement fusion, inertial confinement fusion and high-energy-density physics, space and astronomical plasmas, and plasma technologies for industrial and other applications. The final section before the summary discusses plasma-related databases that could significantly contribute to DDPS. Each primary section starts with a brief introduction to the topic, discusses the state-of-the-art developments in the use of data and/or data-scientific approaches, and presents the summary and outlook. Despite the recent impressive signs of progress, the DDPS is still in its infancy. This article attempts to offer a broad perspective on the development of this field and identify where further innovations are required

Difuze částic z tokamaku vlivem stochastizace magnetických siločar

Práce shrnuje současný stav výzkumu termojaderné fúze s magnetickým udržením a popisuje možnou roli stochastizace magnetických siločar a magnetických perturbací při řešení některých problémů, se kterými se využití fúze potýká. Podává teoretický úvod do problematiky deterministického chaosu a vysvětluje souvislost této teorie s magnetickými perturbacemi v tokamaku. Výsledky jsou prezentovány převážně formou publikací v časopisech a sbornících. Patří mezi ně: srovnání chaotické difuze siločar a částic, kde byly nalezeny podstatné rozdíly, aplikace chaotické difuze částic na problém relativistických elektronů vznikajících při disrupcích, kde naše simulace přispěly k vysvětlení experimentálních výsledků z tokamaku JET, výpočet spekter perturbací a stochastizace siločar pro tokamak COMPASS, sloužící jako příprava na budoucí experimenty, a modelování stínění perturbací plazmatem, kde se pozorování tzv. otisků (footprints) na divertoru ukazuje být slibnou metodou pro detekci stínění.The thesis summarizes the current state of research of thermonuclear fusion with magnetic confinement and decribes the possible role of stochastization of magnetic field lines and magnetic perturbations in solving some of the problems that are encountered on the road to the exploitation of fusion. It presents a theoretical introduction to deterministic chaos and explains the connection of this theory to magnetic perturbations in tokamak. The results are presented mainly in the form of publications in journals and conference proceedings. Among them are: the comparison of chaotic diffusion of particles and field lines, where significant differences were found; the application of chaotic diffusion of particles to the problem of runaway electrons originating in disruptions, where our simulations contributed to explaining the experimental results from the JET tokamak; the calculation of spectra of perturbations for the COMPASS tokamak, done as a preparation for the upcoming experiments; and modelling of screening of perturbations by plasma, where the observations of divertor footprints show as a promising method to detect the screening.Matematicko-fyzikální fakultaFaculty of Mathematics and Physic

Difuze částic z tokamaku vlivem stochastizace magnetických siločar

Difuze částic z tokamaku vlivem stochastizace magnetických siločar Pavel Cahyna Abstrakt: Práce shrnuje současný stav výzkumu termojaderné fúze s magnetickým udržením a popisuje možnou roli stochastizace magnetických siločar a magnetických perturbací při řešení některých problémů, se kterými se využití fúze potýká. Podává teoretický úvod do problematiky determin- istického chaosu a vysvětluje souvislost této teorie s magnetickými pertur- bacemi v tokamaku. Výsledky jsou prezentovány převážně formou publikací v časopisech a sbornících. Patří mezi ně: srovnání chaotické difuze siločar a částic, kde byly nalezeny podstatné rozdíly, aplikace chaotické difuze částic na problém relativistických elektronů vznikajících při disrupcích, kde naše simulace přispěly k vysvětlení experimentálních výsledků z tokamaku JET, výpočet spekter perturbací a stochastizace siločar pro tokamak COMPASS, sloužící jako příprava na budoucí experimenty, a modelování stínění per- turbací plazmatem, kde se pozorování tzv. otisků (footprints) na divertoru ukazuje být slibnou metodou pro detekci stínění. 1Diffusion of particles from tokamak by stochastization of magnetic field lines Pavel Cahyna Abstract: The thesis summarizes the current state of research of ther- monuclear fusion with magnetic confinement and decribes the possible role of stochastization of magnetic field lines and magnetic perturbations in solv- ing some of the problems that are encountered on the road to the exploitation of fusion. It presents a theoretical introduction to deterministic chaos and explains the connection of this theory to magnetic perturbations in tokamak. The results are presented mainly in the form of publications in journals and conference proceedings. Among them are: the comparison of chaotic dif- fusion of particles and field lines, where significant differences were found; the application of chaotic diffusion of particles to the problem of runaway electrons originating in disruptions, where our simulations contributed to ex- plaining the experimental results from the JET tokamak; the calculation of spectra of perturbations for the COMPASS tokamak, done as a preparation for the upcoming experiments; and modelling of screening of perturbations by plasma, where the observations of divertor footprints show as a promising method to detect the screening. 1Ústav teoretické fyzikyInstitute of Theoretical PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

The density limit in fusion plasmas: the role of edge instabilities

This Thesis deals with the study of density limit in magnetically confined fusion plasmas. The density limit causes the termination of the plasma discharge when a threshold value for the electron density is overcome, the so-called Greenwald density (nG), and thus represents an important operative limit for fusion devices. The problem is studied following a multiple point of view approach involving the numerical solution of a single-fluid model for the plasma, the study of plasma transport theory and the analysis of data coming from the reversed-field pinch experiment RFX-mod in Padua, Italy. Analysis of the results from numerical simulations of the reversed-field pinch configuration allows confirming the role of a dimensionless parameter of the model (the Hartmann number H, related to plasma resistivity and viscosity) in describing the transition observed in the dynamics of the plasma and in ruling the behaviour of edge-magnetic field. Analysis of the plasma transport theory allows writing the Hartmann number in terms of plasma measurable quantities. Analysis of a wide set of data coming from the RFX-mod experiment allows linking the trend in edge-magnetic field observed at the onset of the density limit to the (perpendicular) Hartmann number: this supports abandoning the phenomenological nG parameter in favor of H. Furthermore, H describes with a good level of correlation the behaviour of the measured plasma density, temperature and current. The work in this Thesis provides an important confirmation to the use of the single-fluid model in modeling reversed-field pinch plasmas and opens the way towards exploring the possibility that H could be the order parameter also in the tokamak density limit