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Plasma parameters

About: Plasma parameters is a research topic. Over the lifetime, 9050 publications have been published within this topic receiving 128542 citations.


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TL;DR: In this article, it is shown that this limit may be caused by a dramatic deterioration in core particle confinement occurring as the density limit boundary is approached, which can help explain the disruptions and Marfes that are associated with density limit.
Abstract: While the results of early work on the density limit in tokamaks from the ORMAK and DITE groups have been useful over the years, results from recent experiments and the requirements for extrapolation to future experiments have prompted a new look at this subject. There are many physical processes which limit the attainable densities in tokamak plasmas. These processes include: (1) radiation from low Z impurities, convection, charge exchange and other losses at the plasma edge; (2) radiation from low or high Z impurities in the plasma core; (3) deterioration of particle confinement in the plasma core; and (4) inadequate fuelling, often exacerbated by strong pumping by walls, limiters or divertors. Depending upon the circumstances, any of these processes may dominate and determine a density limit. In general, these mechanisms do not show the same dependence on plasma parameters. The multiplicity of processes leading to density limits with a variety of scaling has led to some confusion when comparing density limits for different machines. The authors attempt to sort out the various limits and to extend the scaling law for one of them to include the important effects of plasma shaping, i.e. ;e = k, where ne is the line average electron density (1020 m−3), κ is the plasma elongation and (MAm−2) is the average plasma current density, defined as the total current divided by the plasma cross-sectional area. In a sense, this is the most important density limit since, together with the q-limit, it yields the maximum operating density for a tokamak plasma. It is shown that this limit may be caused by a dramatic deterioration in core particle confinement occurring as the density limit boundary is approached. This mechanism can help explain the disruptions and Marfes that are associated with the density limit.

682 citations

Book
01 Jan 2004
TL;DR: In this paper, the authors present an overview of the physical properties of plasmas in terms of electric and thermal conductivity, as well as the physics of excited molecules in a plasma.
Abstract: PART 1. FUNDAMENTALS OF PLASMA PHYSICS AND PLASMA CHEMISTRY. CHAPTER 1. Introduction CHAPTER 2. ELEMENTARY PROCESSES OF CHARGED SPECIES IN PLASMA. 2.1. Elementary Charged Particles In Plasma, And Their Elastic And Inelastic Collisions. 2.2. Ionization Processes. 2.3. Mechanisms Of Electron Losses: The Electron-Ion Recombination. 2.4. The Electron Losses Due To Formation Of Negative Ions: Electron Attachment And Detachment Processes. 2.5. The Ion-Ion Recombination Processes. 2.6. The Ion-Molecular Reactions. 2.7. Problems and Concept Questions. CHAPTER 3. ELEMENTARY PROCESSES OF EXCITED MOLECULES AND ATOMS IN PLASMA. 3.1. Electronically Excited Atoms And Molecules In Plasma. 3.2. Vibrationally And Rotationally Excited Molecules. 3.3. Elementary Processes Of Vibrational, Rotational And Electronic Excitation Of Molecules In Plasma. 3.4. Vibrational (VT) Relaxation, Landau-Teller Formula. 3.5. Vibrational Energy Transfer Between Molecules, VV-Relaxation Processes. 3.6. Processes Of Rotational And Electronic Relaxation Of Excited Molecules. 3.7. Elementary Chemical Reactions Of Excited Molecules, Fridman - Macheret a-Model. 3.8. Problems and Concept Questions. CHAPTER 4. PLASMA STATISTICS AND KINETICS OF CHARGED PARTICLES. 4.1. Statistics And Thermodynamics Of Equilibrium And Non-Equilibrium Plasmas, The Boltzmann, Saha And Treanor Distributions. 4.2. The Boltzmann And Fokker-Planck Kinetic Equations, Electron Energy Distribution Functions. 4.3. Electric And Thermal Conductivity In Plasma, Diffusion Of Charged Particles. 4.4. Breakdown Phenomena: The Townsend And Spark Mechanisms, Avalanches, Streamers And Leaders. 4.5. Steady-State Regimes Of Non-Equilibrium Electric Discharges. 4.6. Problems and Concept Questions. CHAPTER 5. KINETICS OF EXCITED PARTICLES IN PLASMA. 5.1.Vibrational Distribution Functions In Non-Equilibrium Plasma, The Fokker-Planck Kinetic Equation. 5.2. Non-Equilibrium Vibrational Kinetics: eV-Processes, Polyatomic Molecules, Non-Steady-State Regimes. 5.3. Macrokinetics Of Chemical Reactions And Relaxation Of Vibrationally Excited Molecules. 5.4. Vibrational Kinetics In Gas Mixtures, Isotopic Effect In Plasma Chemistry. 5.5. Kinetics Of Electronically And Rotationally Excited States, Non-Equilibrium Translational Distributions, Relaxation And Reactions Of Hot Atoms In Plasma. 5.6. Energy Efficiency, Energy Balance And Macrokinetics Of Plasma-Chemical Processes. 5.7. Energy Efficiency Of Quasi-Equilibrium Plasma-Chemical Systems, Absolute, Ideal And Super-Ideal Quenching. 5.8. Problems and Concept Questions. CHAPTER 6. ELECTROSTATICS, ELECTRODYNAMICS AND FLUID MECHANICS OF PLASMA. 6.1. Electrostatic Plasma Phenomena: Debye-Radius And Sheaths, Plasma Oscillations And Plasma Frequency. 6.2. Magneto-Hydrodynamics Of Plasma. 6.3. Instabilities Of Low Temperature Plasma. 6.4. Non-Thermal Plasma Fluid Mechanics In Fast Subsonic And Supersonic Flows. 6.5. Electrostatic, Magneto-Hydrodynamic And Acoustic Waves In Plasma. 6.6. Propagation Of Electro-Magnetic Waves In Plasma. 6.7. Emission And Absorption Of Radiation In Plasma, Continuous Spectrum. 6.8. Spectral Line Radiation In Plasma. 6.9. Non-Linear Phenomena In Plasma. 6.10. Problems and Concept Questions. PART 2. PHYSICS AND ENGINEERING OF ELECTRIC DISCHARGES. CHAPTER 7. GLOW DISCHARGE. 7.1. Structure And Physical Parameters Of Glow Discharge Plasma. Current-Voltage Characteristics, Comparison Of Glow And Dark Discharges. 7.2. Cathode And Anode Layers Of A Glow Discharge. 7.3. Positive Column Of Glow Discharge. 7.4. Glow Discharge Instabilities. 7.5. Different Specific Glow Discharge Plasma Sources. 7.6. Problems and Concept Questions. CHAPTER 8. ARC DISCHARGES. 8.1. Physical Features, Types, Parameters And Current-Voltage Characteristics Of Arc Discharges. 8.2. Mechanisms Of Electron Emission From Cathode. 8.3. Cathode And Anode Layers In Arc Discharges. 8.4. Positive Column Of Arc Discharges. 8.5. Different Configurations Of Arc Discharges. 8.6. Gliding Arc Discharge. 8.7. Problems and Concept Questions. CHAPTER 9. NON-EQUILIBRIUM COLD ATMOSPHERIC PRESSURE PLASMAS: CORONA, DIELECTRIC BARRIER AND SPARK DISCHARGES. 9.1. The Continuous Corona Discharge. 9.2. The Pulsed Corona Discharge. 9.3. Dielectric-Barrier Discharge. 9.4. Spark Discharges. 9.5. Problems and Concept Questions. CHAPTER 10. PLASMA CREATED IN HIGH FREQUENCY ELECTROMAGNETIC FIELDS: RADIO-FREQUENCY (RF), MICROWAVE AND OPTICAL DISCHARGES. 10.1. Radio-Frequency (RF) Discharges At High Pressures, Inductively Coupled Thermal RF Discharges. 10.2. Thermal Plasma Generation In Microwave And Optical Discharges. 10.3. Non-Equilibrium Radio-Frequency (RF) Discharges, General Features Of Non-Thermal Capacitively-Coupled (CCP) Discharges. 10.4. Non-Thermal Capacitively-Coupled (CCP) Discharges Of Moderate Pressure. 10.5. Low Pressure Capacitively-Coupled RF Discharges. 10.6. Asymmetric, Magnetron And Other Special Forms Of Low Pressure Capacitive RF-Discharges. 10.7. Non-Thermal Inductively-Coupled (ICP) Discharges. 10.8. Non-Thermal Low-Pressure Microwave And Other Wave-Heated Discharges. 10.9. Non-Equilibrium Microwave Discharges Of Moderate-Pressure. 10.10. Problems and Concept Questions. CHAPTER 11. DISCHARGES IN AEROSOLS, DUSTY PLASMAS. 11.1. Photo-Ionization Of Aerosols. 11.2.Thermal Ionization Of Aerosols. 11.3. Electric Breakdown Of Aerosols. 11.4. Steady-State Dc Electric Discharge In Heterogeneous Medium. 11.5. Dusty Plasma Formation, Evolution Of Nano-Particles In Plasma. 11.6. Critical Phenomena In Dusty Plasma Kinetics. 11.7. Non-Equilibrium Clusterization In Centrifugal Field. 11.8. Dusty Plasma Structures: Phase Transitions, Coulomb Crystals, Special Oscillations. 11.9. Problems and Concept Questions. CHAPTER 12. ELECTRON BEAM PLASMAS. 12.1.Generation And Properties Of Electron-Beam Plasmas. 12.2. Kinetics Of Degradation Processes, Degradation Spectrum. 12.3. Plasma-Beam Discharge. 12.4. Non-Equilibrium High-Pressure Discharges Sustained By High-Energy Electron Beams. 12.5. Plasma In Tracks Of Nuclear Fission Fragments, Plasma Radiolysis. 12.6. Dusty Plasma Generation By A Relativistic Electron Beam. 12.7. Problems and Concept Questions.

612 citations

Journal ArticleDOI
TL;DR: In this paper, the growth process during magnetron sputtering is characterized by the bombardment of the growing film with species from the sputtering target and from the plasma, in addition to sputtered atoms with energies in the eV range.
Abstract: Magnetron sputtering of transparent conductive oxides (zinc oxide, indium tin oxide, tin oxide) is a promising technique which allows the deposition of films at low temperatures with good optical and electronic properties. A special advantage is the scalability to large areas. The principles underlying magnetron sputtering are reviewed in this paper. The growth process during magnetron sputtering is characterized by the bombardment of the growing film with species from the sputtering target and from the plasma. In addition to sputtered atoms with energies in the eV range, ions from the plasma (mostly argon) and neutral atoms (also argon) reflected at the target hit the growing film. Depending on the energy of these species and on the ion-to-neutral ratio the properties of the films vary. High energies ( 100 eV), which occur mainly at low sputtering pressures lead to damage of the growing film, connected with mechanical stress, small crystallites and bad electrical parameters. Ion assisted growth with low ion energies (below about 50 eV) is advantageous as is a high ion-to-neutral ratio. A compilation of resistivities of magnetron sputtered zinc oxide films yields a limiting resistivity of 2 × 10-4 cm for polycrystalline films. Based on the correlation between plasma parameters and film properties new research fields are anticipated.

554 citations

Journal ArticleDOI
TL;DR: In this article, the conditions for solidification in a laboratory plasma are discussed and conditions for the formation of a coulomb lattice are given for small particles in plasmas.
Abstract: Small particles in plasmas can form a coulomb lattice. The conditions for solidification in a laboratory plasma are discussed.

517 citations

Journal ArticleDOI
TL;DR: In this paper, a new technique of the simultaneous excitation of a magnetron sputtering discharge by rf and dc was used for the deposition of undoped ZnO-and Al-doped znO (ZnO:Al) films.
Abstract: A new technique of the simultaneous excitation of a magnetron sputtering discharge by rf and dc was used for the deposition of undoped ZnO- and Al-doped ZnO (ZnO:Al) films. By this technique, it was possible to change the ion-to-neutral ratio ji/jn on the substrates during the film growth by more than a factor of ten, which was revealed by plasma monitor and Langmuir probe measurements. While for a pure dc discharge the ions impinging onto a floating substrate have energies of about Ei≈17 eV, the rf discharge is characterized by Ar-ion energies of about 35 eV. Furthermore, the ion current density for the rf excitation is higher by a factor of about five, which is caused by the higher plasma density in front of the substrate. This leads to a much higher ion-to-neutral ratio ji/jn on the growing film in the case of the rf discharge, which strongly influences the structural and electrical properties of the ZnO(:Al) films. The rf-grown films exhibit about the three times lower specific resistances (ρ≈6×10−4 Ω...

513 citations


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No. of papers in the topic in previous years
YearPapers
202327
202254
2021244
2020259
2019289
2018283