Fields Of Plasma Physics Research Articles

Invariance analysis, optimal system, and group invariant solutions of (3+1)‐dimensional non‐linear MA‐FAN equation

The importance of research on non‐linear evolution equations has increased over time. In the fields of plasma physics, fluid mechanics, optical fibers, and other sciences, such equations are not unrealistic. Discovering the exact answers to these equations needs to be a top priority. In this study, we will investigate a ‐dimensional non‐linear MA‐FAN equation that is used to simulate weakly non‐linear restoring forces and frequency dispersion in long wavelength water waves. The ‐dimensional MA‐FAN equation's solution is analyzed using the Lie symmetry analysis, and it is also used to pick the appropriate one‐dimensional Lie subalgebra system. We discover invariant solutions of the ‐dimensional MA‐FAN equation, which may capture the dynamic behavior of non‐linear waves, by solving the numerous ordinary differential equations that are reduced equations from the MA‐FAN equation by using the Lie group of transformation approach. In conclusion, the method offered is robust and convenient tool for studying various classes of non‐linear PDE solutions.

Molecular data needs for advanced collisional-radiative modelling for hydrogen plasmas

Population models for molecular hydrogen (H2) are applicable in various fields of plasma physics and particularly in fusion research: they are necessary for the evaluation of plasma diagnostics (e.g. optical emission spectroscopy) or can be used to evaluate effective reaction rates for molecular processes (e.g. molecular-assisted recombination in divertor plasmas). The accuracy and completeness of population models for molecular hydrogen is strongly linked to the accuracy and availability of molecular reaction data. While there are recently huge improvements in the field of electron impact cross sections, the shortfalls regarding input data availability persist in the area of collisions between heavy particles and H2. An overview of the status of population models for H and H2 based on the Yacora solver is given. The data needs for collisional-radiative modelling are demonstrated by means of three examples comprising different detail levels, namely a purely electronic collisional-radiative model for the singlet system of H2, a corona model for the Fulcher-α band and a vibrationally resolved collisional-radiative model for the electronic ground state X1 of H2.Graphical abstractElectronic energy level diagram of the hydrogen molecule delimiting the population models discussed in this work

Parametrization of electron sheath expansion for Langmuir probe I-V traces

The Langmuir probe is a common plasma diagnostic widely utilized in various fields of plasma physics, and its associated methods of data analysis remains in active development. In this work, we present an attempt using a power law parametrization model similar to Sheridan's empirical formulation is to describe the sheath expansion effect on electron current in an argon plasma. The fitting results using the power law parametrization method show observably better consistency compared to those using conventional interception method and inflection method. It is also observed that when used to fit the electron saturation current at probe bias voltages well beyond the plasma potential plus the argon ionization energy, resultant curve fitted by power law parametrization, as with that by linear fitting, deviates significantly from the curve fitted at lower bias voltages, albeit the saturation obtained fitted using the power law method remained consistent with that fitted at lower probe bias voltages. Probable causes of this deviation include anode glow or spots near the probe and the changes of the global plasma parameters via electron absorption at very high probe bias. The fact that the resultant electron saturation current remained consistent hints that these non-trival effects can also be approximated by power law parametrization.

Results of scientific research development in the fields of plasma physics and controlled fusion in Russia in 2020

The review is given on the most interesting new results presented at the XLVIII International Zvenigorod conference on plasma physics and controlled fusion which took place in Moscow on March 15–19, 2021. The analysis of basic achievements in the field of plasma physics in Russia and their comparison with scientific researches abroad is carried out.

The IPG6-B as a research facility to support future development of electric propulsion

The inductively-heated plasma generator IPG6-B at Baylor University has been established and characterized in previous years for use as a flexible experimental research facility across multiple applications. The system uses a similar plasma generator design to its twin-facilities at the University of Stuttgart (IPG6-S) and the University of Kentucky (IPG6-UKY). The similarity between these three devices offers the advantage to reproduce results and provides comparability to achieve cross-referencing and verification. Sub- and supersonic flow conditions for Mach numbers between Ma=0.3−1.4 have been characterized for air, argon, helium and nitrogen using a pitot probe. Overall power coupling efficiency as well as specific bulk enthalpy of the flow have been determined by calorimeter measurements to be between η=0.05−0.45 and hs=5−35 MJkg−1 respectively depending on gas type and pressure. Electron temperatures of Te=1−2 eV and densities ne=1018−1020 m−3 have been measured using an electrostatic probe system. At Baylor University, laboratory experiments in the areas of astrophysics, geophysics as well as fundamental research on complex (dusty) plasmas are planned. The study of fundamental processes in low-temperature plasmas connects directly to electric propulsion systems. Most recent experiments include the study of dusty plasmas and astrophysical phenomena and the interaction of charged dust with electric and magnetic fields. In this case, dust can be used as a diagnostic for such fields and can reveal essential information of the magneto-hydrodynamics in low-temperature plasmas. Although some of these goals require further advancement of the facility, it is proposed that several phenomena relevant to electric propulsion as well as to other fields of plasma physics can be studied using the existing facility.

Dynamical structures of solitons and some new types of exact solutions for the (2+1)-dimensional DJKM equation using Lie symmetry analysis

This paper is devoted to obtaining some new types of exact solutions of the (2+1)-dimensional Date–Jimbo–Kashiwara–Miwa (DJKM) equation utilizing the Lie symmetry method. All the Lie symmetries, infinitesimal generators, and possible geometric vector fields have been obtained by using the invariance condition of the group-theoretic method. Meanwhile, the Lie symmetry reductions and explicit exact solutions are obtained by a one-dimensional (1D) optimal system. All the obtained exact solutions are absolutely new and completely different from the earlier established results in the literature. Moreover, the dynamical behavior of obtained solitons like doubly solitons, dark solitons, kink wave, curved shaped multi-solitons, parabolic waves, solitary waves, and annihilation of elastic multi-soliton profiles is depicted graphically via interesting 3D-shapes. That will be widely used to provide many more attractive complex physical phenomena in the fields of plasma physics, statistical physics, fiber optics, fluid dynamics, condensed matter physics, and so on. Finally, we have verified all the achieved soliton solutions through symbolic computations with Mathematica.

Quantum hydrodynamics for plasmas—Quo vadis?

Quantum plasmas are an important topic in astrophysics and high pressure laboratory physics for more than 50 years. In addition, many condensed matter systems, including the electron gas in metals, metallic nanoparticles, or electron-hole systems in semiconductors and heterostructures, exhibit—to some extent—plasmalike behavior. Among the key theoretical approaches that have been applied to these systems are quantum kinetic theory, Green function theory, quantum Monte Carlo, semiclassical and quantum molecular dynamics, and more recently, density functional theory simulations. These activities are in close contact with the experiments and have firmly established themselves in the fields of plasma physics, astrophysics, and condensed matter physics. About two decades ago, a second branch of quantum plasma theory emerged that is based on a quantum fluid description and has attracted a substantial number of researchers. The focus of these studies has been on collective oscillations and linear and nonlinear waves in quantum plasmas. Even though these papers pretend to address the same physical systems as the more traditional papers mentioned above, the former appear to form a rather closed community that is largely isolated from the rest of the field. The quantum hydrodynamics (QHD) results have—with a few exceptions—not found application in astrophysics or in experiments in condensed matter physics. Moreover, these results practically did not have any impact on the former quantum plasma theory community. One reason is the unknown accuracy of the QHD for dense plasmas. In this paper, we present a novel derivation, starting from reduced density operators that clearly point to the deficiencies of QHD, and we outline possible improvements. It is also to be noted that some of the QHD results have attracted negative attention being criticized as unphysical. Examples include the prediction of “novel attractive forces” between protons in an equilibrium quantum plasma, the notion of “spinning quantum plasmas,” or the new field of “quantum dusty plasmas.” In the present article, we discuss the latter system in some detail because it is a particularly disturbing case of formal theoretical investigations that are detached from physical reality despite bold and unproven claims of importance for, e.g., dense astrophysical plasmas or microelectronics. We stress that these deficiencies are not a problem of QHD itself, which is a powerful and efficient method, but rather are due to ignorance of its properties and limitations. We analyze the common flaws of these works and come up with suggestions to improve the situation of QHD applications to quantum plasmas.

A new numerical description of the interaction of an ion beam with a magnetized plasma in an ECR-based charge breeding device

The ion beam-plasma interaction is a relevant topic in several fields of plasma physics, from fusion devices to modern ion sources. This paper discusses the numerical modelling of the whole beam-plus-plasma-target system in case of 1+ ions entering an ECR-based charge breeder (ECR-CB). The model is able to reproduce the ion capture and the creation of the first charge states in the selected physics case, i.e. the interaction of a 85Rb1+ ions with the plasma of the 14.5 GHz PHOENIX ECR-CB installed at the Laboratoire de Physique Subatomique et de Cosmologie (LPSC) of Grenoble. The results show that a very narrow window of physical parameters for both the beam (energy and energy spread especially) and plasma (ion temperature, density, density structural distribution, self-generated ambipolar fields) exists which is able to reproduce very well the experimental results, providing an exhaustive picture of the involved phenomena. Possible non-linear interactions and the role played by the eventual onset of instabilities are also discussed.

Electron scattering with metastable H*2(c3Πu) molecules: ionization and other total cross sections

In this paper, we report total cross sections for electron-induced ionization and excitations from both the excited metastable state H*2(c3Пu) and the electronic ground state of H2. Total cross sections are reported for incident energies from the ionization threshold to 2000 eV using the ‘complex scattering potential-–ionization contribution’ method and the relative importance of various scattering channels, including super-elastic scattering and ionization, are identified. There appear to be no previous data on the ionization cross sections for the metastable target H*2(c3Пu). This work has potential applications in the fields of plasma physics and planetary atmospheres.

THE PHYSICS OF BURNING PLASMAS IN TOROIDAL MAGNETIC FIELD DEVICES

Some of the crucial physics aspects of burning plasmas magnetically confined in toroidal systems are presented from the viewpoint of nonlinear dynamics. Most of the discussions specifically refer to tokamaks, but they can be readily extended to other toroidal confinement devices. Particular emphasis is devoted to fluctuation induced transport processes of mega electron volts energetic ions and charged fusion products as well as to energy and particle transports of the thermal plasma. Long time scale behaviors due to the interplay of fast ion induced collective effects and plasma turbulence are addressed in the framework of burning plasmas as complex self-organized systems. The crucial roles of mutual positive feedbacks between theory, numerical simulation and experiment are shown to be the necessary premise for reliable extrapolations from present day laboratory to burning plasmas. Examples of the broader applications of fundamental problems to other fields of plasma physics and beyond are also given.

Cross section data for electron collisions in plasma physics

We present a survey of cross section data for electron collisions used in plasma physics. Needs for cross section data have been identified in different fields of plasma physics and a brief review of existing data on electron/radical data has been presented. Experimental capabilities and recent results obtained in the Belgrade Laboratory for Atomic Collision Processes have been discussed.

Physics of burning plasmas in toroidal magnetic confinement devices

Some of the crucial physics aspects of burning plasmas magnetically confined in toroidal systems are presented from the viewpoint of nonlinear dynamics. Most of the discussions specifically refer to tokamaks, but they can be readily extended to other toroidal confinement devices. Particular emphasis is devoted to fluctuation induced transport processes of mega electron volts energetic ions and charged fusion products as well as to energy and particle transports of the thermal plasma. Long time scale behaviours due to the interplay of fast ion induced collective effects and plasma turbulence are addressed in the framework of burning plasmas as complex self-organized systems. The crucial roles of mutual positive feedbacks between theory, numerical simulation and experiment are shown to be the necessary premise for reliable extrapolations from present day laboratory to burning plasmas. Examples of the broader applications of fundamental problems to other fields of plasma physics and beyond are also given.

Magnetic fluctuation spectra and non-linear MHD mode interaction in RFX

Non-linear interaction of magnetohydrodynamic (MHD) modes sustaining the reversed field pinch configuration is an important field of research with many implications in different fields of plasma physics. The dynamo mechanism can be supported by different magnetic fluctuation spectra when the same magnetic boundary is considered. In this paper we study and characterize magnetic spectra in RFX from a statistical point of view during stationary regimes both from the global equilibrium point of view and also in the sense of the distribution of the amplitude of the magnetic fluctuations . Three classes of spectra are defined according to their spectral composition. Correlation with global plasma quantities such as plasma current, density and reversal parameter are investigated in order to point out the parameters controlling the number of interacting modes. It is found that field errors also play an important role in the evolution towards large or narrow spectra. To investigate the non-linear interaction of magnetic fluctuations, bispectral analysis proved to be a powerful tool. A new relation between spontaneous rotation of some modes (always phase and wall locked in RFX standard discharges) and narrow spectra is obtained and discussed.

Atmospheric Transport, Dispersion, and Chemical Reactions in Air Pollution: A Review

Martin Hoffert is presently a Member of the Research Staff at Riverside Research Institute in New York City. His academic background includes a B.S. (1960) in Aeronautical Engineering from the University of Michigan, an M.S. (1964) and Ph.D. (1967) from the Polytechnic Institute of Brooklyn in Astronautics, and an M.A. (1969) from the New School for Social Research where he did graduate work in sociology. Professionally, he has been on the staff of the Curtiss-Wright Corporation, Wood-Ridge, N.J., General Applied Science Laboratories Inc., Westbury, N.Y., Advanced Technology Laboratories Inc., Jericho, N.Y., and New York University; and has publications in the fields of plasma physics, ionization kinetics, turbulent flows and three-dimensional boundary-layer theory. At Riverside Research Institute he has, since 1969, worked on various problems in atmospheric and re-entry physics. Dr. Hoffert has more recently also been concerned with applications of aerospace sciences to environmental and social problems; dispersion modeling of air pollution being a most promising example. He is a Member of the AIAA, the American Physical Society and the American Association for the Advancement of Science.