286 Matching Results

Search Results

Advanced search parameters have been applied.

MINOS test toroid magnetic measurements

Description: Magnetic measurements were made on a test ring constructed from the same steel used on the prototype MINOS far detector plate located in NMS. The conventionally used technique of measuring sense coil voltage induced by step changes in excitation current voltage was successful in providing stable, repeatable measurements. Measurements were made at several locations on the steel and the results are presented.
Date: March 3, 1999
Creator: Jaskierny, Robert C. Trendler and Walter F.
Partner: UNT Libraries Government Documents Department

Comment on Turbulent Equipartition Theory of Toroidal Momentum Pinch

Description: This response demonstrates that the comment by Peeters et al. contains an incorrect and misleading interpretation of our paper [Hahm et al., Phys. Plasmas 15, 055902 (2008)] regarding the density gradient dependence of momentum pinch and the turbulent equipartition (TEP) theory.
Date: March 12, 2009
Creator: T.S. Hahm, P.H. Diamond, O.D. Gurcan, and G. Rewoldt
Partner: UNT Libraries Government Documents Department

The toroidal field coil design for ARIES-ST

Description: An evolutionary process was used to develop the toroidal field (TF) coil design for the ARIES-ST (Spherical Tokamak). Design considerations included fabricability, assembly, maintenance, energy efficiency, and structural robustness. The design addresses a number of the concerns (complexity) and criticisms (high cost, high recirculating power) of fusion. It does this by: (1) Applying advanced, but available laser forming and spray casting techniques for manufacturing the TF coil system; (2) Adopting a simple single toroidal field coil system to make assembly and maintenance much easier, the single turn design avoids the necessity of using the insulation as a structural component of the TF coils, and hence is much more robust than multi-turn designs; and (3) Using a high conductivity copper alloy and modest current densities to keep the recirculating power modest.
Date: January 21, 2000
Creator: Reiersen, W.; Dahlgren, F.; Fan, H.M.; Neumeyer, C. & Zatz, I.
Partner: UNT Libraries Government Documents Department

Theory, simulation, and experimental studies of zonal flows

Description: The authors report on current theoretical understanding of the characteristics of self-generated zonal flows as observed in nonlinear gyrokinetic simulations of toroidal ITG turbulence [Science 281, 1835 (1998)], and discuss various possibilities for experimental measurements of signature of zonal flows.
Date: July 13, 2000
Creator: Hahm, T. S.; K.H.Burrell; Z.Lin; Nazikian, R. & Synakowski, E.J.
Partner: UNT Libraries Government Documents Department

Fusion ignition research experiment

Description: Understanding the properties of high gain (alpha-dominated) fusion plasmas in an advanced toroidal configuration is the largest remaining open issue that must be addressed to provide the scientific foundation for an attractive magnetic fusion reactor. The critical parts of this science can be obtained in a compact high field tokamak which is also likely to provide the fastest and least expensive path to understanding alpha-dominated plasmas in advanced toroidal systems.
Date: July 18, 2000
Creator: Meade, Dale
Partner: UNT Libraries Government Documents Department

Fabrication of large radii toroidal surfaces by single point diamond turning

Description: An unconventional machining technique has been developed for producing relatively large radii quasi-toroidal surfaces which could not normally be produced by conventional diamond turning technology. The maximum radial swing capacity of a diamond turning lathe is the limiting factor for the rotational radius of any toroid. A typical diamond turned toroidal surface is produced when a part is rotated about the spindle axis while the diamond tool contours the surface with any curved path. Toric surfaces sliced horizontally, have been used in laser resonator cavities. This paper will address the fabrication of a special case of toroids where a rotating tool path is a circle whose center is offset from the rotational axis of the toroid by a distance greater than the minor radius of the tool path. The quasi-toroidal surfaces produced by this technique approximate all asymmetrical combinations of concave/convex section of a torus. Other machine configurations have been reported which offer alternative approaches to the fabrication of concave asymmetric aspheric surfaces. Prototypes of unique lenses each having two quasi-toroidal surfaces were fabricated in the Ultraprecision Manufacturing Technology Center at form key components of a scanned laser focusing system. As an example of the problem faced, the specifications for one of the surfaces was equivalent to a section of a torus with a two meter diameter hole. The lenses were fabricated on a Nanoform 600 diamond turning lathe. This is a numerically controlled two axis T-base lathe with an air bearing spindle and oil hydrostatic slides. The maximum radial swing for this machine is approximately 0.3 meters.
Date: December 31, 1995
Creator: Cunningham, J.P.; Marlar, T.A.; Miller, A.C. & Paterson, R. L.
Partner: UNT Libraries Government Documents Department

Science and Technology of the 10-MA Spherical Tori

Description: The Spherical Torus (ST) configuration has recently emerged as an example of confinement concept innovation that enables attractive steps in the development of fusion energy. The scientific potential for the ST has been indicated by recent encouraging results from START,2 CDX-U, and HIT. The scientific principles for the D-fueled ST will soon be tested by NSTX (National Spherical Torus Experiment3) in the U.S. and MAST (Mega-Amp Spherical Tokamak4) in the U.K. at the level of l-2 MA in plasma current. More recently, interest has grown in the U.S. in the possibility of near-term ST fusion burn devices at the level of 10 MA in plasma current. The missions for these devices would be to test burning plasma performance in a small, pulsed D-T-fueled ST (i.e., DTST) and to develop fusion energy technologies in a small steady state ST-based Volume Neutron Source (VNS). This paper reports the results of analysis of the key science and technology issues for these devices.
Date: November 14, 1999
Creator: Peng, Y-K.M.
Partner: UNT Libraries Government Documents Department

Observation of new branch of toroidal Alfven eigenmodes in TFTR

Description: Experimental observations are presented of a new branch of the toroidal Alfven eigenmode spectrum during ICRF heating of plasmas on TFTR. The identification of the second branch is based largely on direct measurements of the toroidal mode numbers of the toroidal Alfven Eigenmodes, and by the differences in the time evolution of the frequency spectrum between the new branch and the original toroidal Alfven eigenmodes as reported by Taylor et al. Phys. Fluids B 5 2437 (1993). The new branch has so far only been observed in relatively low edge q(=4-4.5) plasmas.
Date: November 1, 1995
Creator: Fredrickson, E.; Budny, R. & Chang, Z.
Partner: UNT Libraries Government Documents Department

Fusion Ignition Research Experiment System Integration

Description: The FIRE (Fusion Ignition Research Experiment) configuration has been designed to meet the physics objectives and subsystem requirements in an arrangement that allows remote maintenance of in-vessel components and hands-on maintenance of components outside the TF (toroidal-field) boundary. The general arrangement consists of sixteen wedged-shaped TF coils that surround a free-standing central solenoid (CS), a double-wall vacuum vessel and internal plasma-facing components. A center tie rod is used to help support the vertical magnetic loads and a compression ring is used to maintain wedge pressure in the inboard corners of the TF coils. The magnets are liquid nitrogen cooled and the entire device is surrounded by a thermal enclosure. The double-wall vacuum vessel integrates cooling and shielding in a shape that maximizes shielding of ex-vessel components. The FIRE configuration development and integration process has evolved from an early stage of concept selection to a higher level of machine definition and component details. This paper describes the status of the configuration development and the integration of the major subsystem components.
Date: November 1, 1999
Creator: Brown, T.
Partner: UNT Libraries Government Documents Department

Time-Scales for Non-Inductive Current Buildup in Low-Aspect-Ratio Toroidal Geometry

Description: The fundamental differences between inductive and non-inductive current buildup are clarified and the associated time-scales and other implications are discussed. A simulation is presented whereby the plasma current in a low-aspect-ratio torus is increased primarily by the self-generated bootstrap current with only 10% coming from external current drive. The maximum obtainable plasma current by this process is shown to scale with the toroidal field strength. The basic physics setting the time-scales can be obtained from a 1D analysis. Comparisons are made between the timescales found here and those reported in the experimental literature.
Date: November 1, 1999
Creator: Jardin, S.C.
Partner: UNT Libraries Government Documents Department

Toroidal Effects on ICRF Heating and Current Drive

Description: Numerical studies, performed with the Monte-Carlo code FIDO [1], of the evolution of the resonant-ion distribution function in the presence of ICRH in toroidal geometry are presented. In particular it is pointed out how the absorption of toroidal momentum from a wave field with finite parallel wave numbers causes spatial drift and diffusion, which together with the finite orbit widths of the tail ions is shown to have a large effect on the temperature profile of the resonant ion species and also to cause losses of high-energy ions to the wall [2]. Furthermore, it is found that the finite orbit width and the inward drift occuring for negative parallel wave numbers [3] each give rise to a new mechanism of minority-ion cyclotron current drive as compared to earlier models where the drift orbits of the resonant ions are confined to the magnetic flux surfaces. For high levels of coupled power these new mechanisms are found to be the dominating ones [4,5].
Date: April 12, 1999
Creator: Carlsson, J.; Hedin, J. & Hellsten, T.
Partner: UNT Libraries Government Documents Department

Analysis of the 50 kG toroidal field coil for high field ORMAK

Description: From 5th symposium on engineering problems of fusion research; Princeton, New Jersey, USA (6 Nov 1973). Due to space limitations on the windings, the power efficiencies of toroidal field coils for tokamak experiments are in general rather poor. Very substantial improvement can be achieved by using asymmetrical magnet coil designs. The results of mathematical analysis and electric-current-flow plotting for various types of asymmetrical coil designs are discussed, and numerical data of resistance measurements with the High-Field ORMAK prototype coil are given. (auth)
Date: January 1, 1973
Creator: Gauster, W.F. & Walstrom, P.L.
Partner: UNT Libraries Government Documents Department

Structural analysis of the ITER vacuum vessel from disruption loading with halo asymmetry

Description: Static structural analyses of the ITER vacuum vessel were performed with toroidally asymmetric disruption loads. Asymmetric halo current conditions were assumed to modify symmetric disruption loads which resulted in net lateral loading on the vacuum vessel torus. Structural analyses with the asymmetric loading indicated significantly higher vessel stress and blanket support forces than with symmetric disruption loads. A recent change in the vessel support design which provided toroidal constraints at each mid port was found to be effective in reducing torus lateral movement and vessel stress.
Date: July 1, 1996
Creator: Riemer, B.W. & Sayer, R.O.
Partner: UNT Libraries Government Documents Department

Physics basis for the Fusion Ignition Research Experiment (FIRE)

Description: Understanding the properties of high gain (alpha-dominated) fusion plasmas in an advanced toroidal configuration is a critical issue that must be addressed to provide the scientific foundation for an attractive magnetic fusion reactor. The functional fusion plasma objectives for major next physics steps in magnetic fusion research can be described as: Burning Plasma Physics - The achievement and understanding of alpha-dominated plasmas that have characteristics similar to those expected in a fusion energy source, and Advanced Toroidal Physics - The achievement and understanding of bootstrap-current-dominated plasmas with externally controlled profiles and other characteristics (e.g. confinement and beta) similar to those expected in an attractive fusion system.
Date: July 7, 2000
Creator: Meade, D. M.; Thome, R. J.; Sauthoff, N. R.; Heitzenroeder, P. J.; Nelson, B. E.; Ulrickson, M.A et al.
Partner: UNT Libraries Government Documents Department

Low Frequency Fishbone Mode Induced by Circulating Particles in Spherical Tori

Description: It is found that high beta in low-aspect-ratio tori tends to stabilize the fishbone instability in a plasma with energetic circulating ions. The stabilization results from enhancement of the toroidal drift motion by large Shafranov shift, which makes it difficult to reconcile the condition of considerable energy exchange between the ions and the internal kink perturbation with the condition of the resonant wave-particle interaction.
Date: February 2, 2001
Creator: Kolesnichenko, Ya.I.; Marchenko, V.S. & White, R.B.
Partner: UNT Libraries Government Documents Department

Method and Apparatus to Produce and Maintain a thick, flowing, Liquid Lithium first wall for Toroidal Magnetic Confinement DT Fusion Reactors

Description: A system for forming a thick flowing liquid metal, in this case lithium, layer on the inside wall of a toroid containing the plasma of a deuterium-tritium fission reactor. The presence of the liquid metal layer or first wall serves to prevent neutron damage to the walls of the toroid. A poloidal current in the liquid metal layer is oriented so that it flows in the same direction as the current in a series of external magnets used to confine the plasma. This current alignment results in the liquid metal being forced against the wall of the toroid. After the liquid metal exits the toroid it is pumped to a heat extraction and power conversion device prior to being reentering the toroid.
Date: October 21, 1998
Creator: Woolley, Robert D.
Partner: UNT Libraries Government Documents Department