Download or read book TOROID ROTATION IN NEUTRAL BEAM HEATED DISCHARGES IN DIII D written by and published by . This book was released on 2002 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is known that the toroidal angular momentum and the ion thermal energy are correlated in tokamak discharges heated by neutral beam injection. Here, data from ten years of measurements on DIII-D are considered, for representative discharges from all types and all conditions. The ratio of simple replacement times for momentum and energy is found to order this correlation indicating that these times are approximately equal, across the minor radius. Representative discharges of several types are discussed in more detail, as well as transport analysis results for the momentum and thermal ion diffusivities.
Download or read book Plasma Rotation and Rf Heating in DIII D written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a variety of discharge conditions on DIII-D it is observed that rf electron heating reduces the toroidal rotation speed and core ion temperature. The rf heating can be with either fast wave or electron cyclotron heating and this effect is insensitive to the details of the launched toroidal wavenumber spectrum. To date all target discharges have rotation first established with co-directed neutral beam injection. A possible cause is enhanced ion momentum and thermal diffusivity due to electron heating effectively creating greater anomalous viscosity. Another is that a counter directed toroidal force is applied to the bulk plasma via rf driven radial current.
Download or read book Local Analysis of Confinement and Transport in Neutral Beam Heated DIII D Discharges with Negative Magnetic Shear written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High triangularity double-null discharges with weak or negative central magnetic shear and with both an L-mode and an H-mode edge have been produced on DIII-D. The L-mode edge cases are characterized by peaked toroidal rotation, ion temperature, and plasma density profiles with reduced ion transport in the negative shear region. The H-mode edge cases have broader profiles consistent with reduced ion transport, to the neoclassical level, over the entire plasma cross section. The L-mode edge cases have a greater reduction in central ion diffusivity with stronger negative shear while the H-mode edge cases do not exhibit this dependence. Plasma fluctuation measurements show that a dramatic reduction in turbulence accompanies the improved ion confinement. Calculations of sheared E x B flow indicate that this mechanism can overcome the[eta][sub i] mode growth rate in the region of reduced transport.
Download or read book Collisionality Scaling of Main ion Toroidal and Poloidal Rotation in Low Torque DIII D Plasmas written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In tokamak plasmas with low levels of toroidal rotation, the radial electric fi eld Er is a combination of pressure gradient and toroidal and poloidal rotation components, all having similar magnitudes. In order to assess the validity of neoclassical poloidal rotation theory for determining the poloidal rotation contribution to Er, D[alpha] emission from neutral beam heated tokamak discharges in DIII-D [J.L. Luxon, Nucl. Fusion 42, 614 (2002)] has been evaluated in a sequence of low torque (electron cyclotron resonance heating and balanced diagnostic neutral beam pulse) discharges to determine the local deuterium toroidal rotation velocity. By invoking the radial force balance relation the deuterium poloidal rotation can be inferred. It is found that the deuterium poloidal low exceeds the neoclassical value in plasmas with collisionality [nu]i
Download or read book The Influence of the Dynamic Ergodic Divertor on the Radial Electric Field at the Tokamak TEXTOR written by Jan Willem Coenen and published by Forschungszentrum Jülich. This book was released on 2009 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Toroidal Rotation and Core Ion Confinement with RF Heating in DIII D written by and published by . This book was released on 1999 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shear in the E x B flow velocity can stabilize turbulent transport [1], and so it is of interest to understand the physics behind electric field generation and modification in the tokamak. In DIII-D the core radial electric field in many regimes is generated by flow velocities driven by momentum input from neutral beam injection (NBI). In a variety of conditions it is observed that direct electron heating is accompanied by a reduction in the NBI driven toroidal rotation velocity, U{sub {phi}}, and the ion temperature, T{sub i}, primarily in the core, [rho]
Download or read book Resistive Wall Modes and Plasma Rotation in DIII D written by and published by . This book was released on 2003 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: A271 RESISTIVE WALL MODES AND PLASMA ROTATION IN DIII-D. The stabilization of the resistive wall mode (RWM) by toroidal plasma rotation has been demonstrated in neutral beam heated DIII-D discharges for values of [beta] up to 70% above the no-wall stability limit. The stabilizing effect of plasma rotation is explained by assuming some dissipation, which is caused by the rapid plasma flow through a perturbed magnetic field. Sufficient plasma rotation is predicted to extend the operating regime of tokamaks from the conventional no-wall [beta] limit up to the ideal wall [beta] limit. While plasma rotation has a stabilizing effect on the RWM, a finite amplitude RWM also increases the drag on the plasma, which leads to a non-linear interaction between the RWM and the plasma rotation. A good understanding of the underlying dissipation mechanism is crucial for reliable predictions of the plasma rotation which will be required for wall-stabilization in a burning-plasma experiment. In order to measure the stabilizing effect of plasma rotation on the RWM the technique of active MHD spectroscopy, which was previously applied to MHD modes at frequencies above 10 kHz, is extended to frequencies of a few Hz.
Download or read book Tokamaks written by John Wesson and published by Oxford University Press. This book was released on 2011-10-13 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt: The tokamak is the principal tool in controlled fusion research. This book acts as an introduction to the subject and a basic reference for theory, definitions, equations, and experimental results. The fourth edition has been completely revised, describing their development of tokamaks to the point of producing significant fusion power.
Download or read book Nuclear Fusion written by and published by . This book was released on 2006 with total page 1144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reduction of Toroidal Rotation by Fast Wave Power in DIII D written by and published by . This book was released on 1997 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The application of fast wave power in DIII-D has proven effective for both electron heating and current drive. Since the last RIF Conference FW power has been applied to advanced confinement regimes in DIII-D; negative central shear (NCS), VH- and H-modes, high [beta]{sub p}, and high-li. Typically these regimes show enhanced confinement of toroidal momentum exhibited by increased toroidal rotation velocity. Indeed, layers of large shear in toroidal velocity are associated with transport barriers. A rather common occurrence in these experiments is that the toroidal rotation velocity is decreased when the FW power is turned on, to lowest order independent of whether the antennas are phased for co or counter current drive. At present all the data is for co-injected beams. The central toroidal rotation can be reduced to 1/2 of the non-FW level. Here the authors describe the effect in NCS discharges with co-beam injection.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-10 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fusion Energy Update written by and published by . This book was released on 1986 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radio Frequency Power in Plasmas written by Tak K. Mau and published by American Inst. of Physics. This book was released on 2001-11-09 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume includes the most recent research advances in the application of RF power in plasmas, mainly in fusion science. Most papers deal with plasma heating and current drive, profile control, and stabilization using RF techniques, with some on RF sources and launchers. New and exciting results from all major tokamak experiments, and from theory and modeling are included. There is also a paper on RFplasma application in space propulsion by an active NASA astronaut. This book is a valuable reference for the RF researchers in fusion and other disciplines.
Download or read book Fusion Technology 1994 written by K. Herschbach and published by Newnes. This book was released on 2012-12-02 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the Symposium on Fusion Technology (SOFT) conference is to set the stage for the exchange of information on the design, construction, and operation of fusion experiments and the technology which is being developed for the next-step devices and for fusion reactors. These proceedings therefore present an up-to-date and throrough review of the state-of-the art in this dynamic field.
Download or read book Electron Cyclotron Emission and Electron Cyclotron Resonance Heating EC 16 written by Ronald Prater and published by World Scientific. This book was released on 2011 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume, the sixteenth in a biannual series, presents a snapshot of the state of current research worldwide on Electron Cyclotron Emission (ECE) and Electron Cyclotron Resonance Heating (ECRH) and related technologies. The papers address the physics, both theory and experiment, of ECE and ECRH. The technologies of high power millimeter-wave sources - gyrotrons - and transmission lines and launchers are included. The focus is on physics and technology relevant to the research and development of nuclear fusion.
Download or read book Electron Cyclotron Emission And Electron Cyclotron Resonance Heating Ec 16 Proceedings Of The 16th Joint Workshop With Cd rom written by Ronald Prater and published by World Scientific. This book was released on 2011-02-21 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume, the sixteenth in a biannual series, presents a snapshot of the state of current research worldwide on Electron Cyclotron Emission (ECE) and Electron Cyclotron Resonance Heating (ECRH) and related technologies. The papers address the physics, both theory and experiment, of ECE and ECRH. The technologies of high power millimeter-wave sources — gyrotrons — and transmission lines and launchers are included. The focus is on physics and technology relevant to the research and development of nuclear fusion.
