Next generation toroidal devices
International Nuclear Information System (INIS)
Yoshikawa, Shoichi
1998-10-01
A general survey of the possible approach for the next generation toroidal devices was made. Either surprisingly or obviously (depending on one's view), the technical constraints along with the scientific considerations lead to a fairly limited set of systems for the most favorable approach for the next generation devices. Specifically if the magnetic field strength of 5 T or above is to be created by superconducting coils, it imposes minimum in the aspect ratio for the tokamak which is slightly higher than contemplated now for ITER design. The similar technical constraints make the minimum linear size of a stellarator large. Scientifically, it is indicated that a tokamak of 1.5 times in the linear dimension should be able to produce economically, especially if a hybrid reactor is allowed. For the next stellarator, it is strongly suggested that some kind of helical axis is necessary both for the (almost) absolute confinement of high energy particles and high stability and equilibrium beta limits. The author still favors a heliac most. Although it may not have been clearly stated in the main text, the stability afforded by the shearless layer may be exploited fully in a stellarator. (author)
Next generation toroidal devices
Energy Technology Data Exchange (ETDEWEB)
Yoshikawa, Shoichi [Princeton Plasma Physics Lab., Princeton Univ., NJ (United States)
1998-10-01
A general survey of the possible approach for the next generation toroidal devices was made. Either surprisingly or obviously (depending on one`s view), the technical constraints along with the scientific considerations lead to a fairly limited set of systems for the most favorable approach for the next generation devices. Specifically if the magnetic field strength of 5 T or above is to be created by superconducting coils, it imposes minimum in the aspect ratio for the tokamak which is slightly higher than contemplated now for ITER design. The similar technical constraints make the minimum linear size of a stellarator large. Scientifically, it is indicated that a tokamak of 1.5 times in the linear dimension should be able to produce economically, especially if a hybrid reactor is allowed. For the next stellarator, it is strongly suggested that some kind of helical axis is necessary both for the (almost) absolute confinement of high energy particles and high stability and equilibrium beta limits. The author still favors a heliac most. Although it may not have been clearly stated in the main text, the stability afforded by the shearless layer may be exploited fully in a stellarator. (author)
Toroidal plasmoid generation via extreme hydrodynamic shear.
Gharib, Morteza; Mendoza, Sean; Rosenfeld, Moshe; Beizai, Masoud; Alves Pereira, Francisco J
2017-11-28
Saint Elmo's fire and lightning are two known forms of naturally occurring atmospheric pressure plasmas. As a technology, nonthermal plasmas are induced from artificially created electromagnetic or electrostatic fields. Here we report the observation of arguably a unique case of a naturally formed such plasma, created in air at room temperature without external electromagnetic action, by impinging a high-speed microjet of deionized water on a dielectric solid surface. We demonstrate that tribo-electrification from extreme and focused hydrodynamic shear is the driving mechanism for the generation of energetic free electrons. Air ionization results in a plasma that, unlike the general family, is topologically well defined in the form of a coherent toroidal structure. Possibly confined through its self-induced electromagnetic field, this plasmoid is shown to emit strong luminescence and discrete-frequency radio waves. Our experimental study suggests the discovery of a unique platform to support experimentation in low-temperature plasma science. Copyright © 2017 the Author(s). Published by PNAS.
Finite toroidal flow generated by unstable tearing mode in a toroidal plasma
Energy Technology Data Exchange (ETDEWEB)
Hao, G. Z., E-mail: haogz@swip.ac.cn; Wang, A. K.; Xu, Y. H.; He, H. D.; Xu, M.; Qu, H. P.; Peng, X. D.; Xu, J. Q.; Qiu, X. M. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Sun, Y. [Institute of Plasma Physics, Chinese Academic of Sciences, P.O. Box 1126, Hefei 230031 (China); Cui, S. Y. [School of Mathematics and Statistics Science, Ludong University, Yantai 264025 (China)
2014-12-15
The neoclassical toroidal plasma viscosity torque and electromagnetic torque, generated by tearing mode (TM) in a toroidal plasma, are numerically investigated using the MARS-Q code [Liu et al., Phys. Plasmas 20, 042503 (2013)]. It is found that an initially unstable tearing mode can intrinsically drive a toroidal plasma flow resulting in a steady state solution, in the absence of the external momentum input and external magnetic field perturbation. The saturated flow is in the order of 0.5%ω{sub A} at the q=2 rational surface in the considered case, with q and ω{sub A} being the safety factor and the Alfven frequency at the magnetic axis, respectively. The generation of the toroidal flow is robust, being insensitive to the given amplitude of the perturbation at initial state. On the other hand, the flow amplitude increases with increasing the plasma resistivity. Furthermore, the initially unstable tearing mode is fully stabilized by non-linear interaction with the self-generated toroidal flow.
Generation of toroidal pre-heat plasma
International Nuclear Information System (INIS)
Ikeda, Nagayasu; Tamaru, Ken; Nagata, Akiyoshi.
1979-01-01
The characteristics of toroidal plasma in the initial stage of electric discharge were investigated. A small toroidal-pinch system was used for the present work. A magnetic probe was used to measure the magnetic field. The time of beginning of discharge was determined by observing the variation of the magnetic field. The initial gas pressure dependence of the induced electric field regions, in which electric discharge can be caused, was studied. It is necessary to increase the initial induced electric field for starting discharge. The delay time of large current discharge was measured, and it was about 2 microsecond. Dependences of the electric fields at the beginning of discharge on the charging voltage of capacitors, on the initial gas pressure, and on the discharge frequency were studied. The formation mechanism of plasma column was analyzed. (Kato, T.)
High #betta# and toroidal effects on the internal kink mode in tokamaks
International Nuclear Information System (INIS)
Schmalz, R.
1982-09-01
The inclusion of high-#betta# and first-order toroidal terms in the reduced set of (resistive) MHD equations affords the possibility of improving the study of tokamak plasma behaviour by three-dimensional numerical simulation. A new code, GALA, based on the reduced equations is developed. It is used to analyse the linear and nonlinear behaviour of the internal kink mode in equilibria which are generated by a simple relaxation procedure. We find that the inclusion of toroidal effects in high-#betta# equilibria provides considerable stabilization. (orig.)
The Superconducting Toroid for the New International AXion Observatory (IAXO)
Shilon, I.; Silva, H.; Wagner, U.; ten Kate, H.H.J.
2013-01-01
IAXO, the new International AXion Observatory, will feature the most ambitious detector for solar axions to date. Axions are hypothetical particles which were postulated to solve one of the puzzles arising in the standard model of particle physics, namely the strong CP (Charge conjugation and Parity) problem. This detector aims at achieving a sensitivity to the coupling between axions and photons of one order of magnitude beyond the limits of the current detector, the CERN Axion Solar Telescope (CAST). The IAXO detector relies on a high-magnetic field distributed over a very large volume to convert solar axions to detectable X-ray photons. Inspired by the ATLAS barrel and end-cap toroids, a large superconducting toroid is being designed. The toroid comprises eight, one meter wide and twenty one meters long racetrack coils. The assembled toroid is sized 5.2 m in diameter and 25 m in length and its mass is about 250 tons. The useful field in the bores is 2.5 T while the peak magnetic field in the windings is 5....
Generation of stable mixed-compact-toroid rings by inducing plasma currents in strong E rings
International Nuclear Information System (INIS)
Jayakumar, R.; Taggart, D.P.; Parker, M.R.; Fleischmann, H.H.
1989-01-01
In the RECE-Christa device, hybrid-type compact toroid rings are generated by inducing large toroidal plasma currents I rho in strong electron rings using a thin induction coil positioned along the ring axis. Starting from field-reversal values δ ο = 50 - 120 percent of the original pure fast-electron ring, the induced plasma current I rho raises δ to a maximum value of up to 240 percent with I rho contributing more than 50 percent of the total ring current. Quite interestingly, the generated hybrid compact toroid configurations appear gross-stable during the full I rho pulse length (half-amplitude width about 100 μs)
Current generation by unidirectional lower hybrid waves in the ACT-1 toroidal device
International Nuclear Information System (INIS)
Wong, K.L.; Horton, R.; Ono, M.
1980-05-01
An unambiguious experimental observation of current generation by unidirectional lower hybrid waves in a toroidal plasma is reported. Up to 10 amperes of current was driven by 500 watts of rf power at 160 MHz
Physics of electron internal transport barrier in toroidal helical plasmas
International Nuclear Information System (INIS)
Itoh, K.; Toda, S.; Fujisawa, A.; Ida, K.; Itoh, S.-I.; Yagi, M.; Fukuyama, A.; Diamond, P.H.
2006-10-01
The role of zonal flows in the formation of the transport barrier in the helical plasmas is analyzed using the transport code. A set of one-dimensional transport equations is analyzed, including the effect of zonal flows. The turbulent transport coefficient is shown to be suppressed when the plasma state changes from the weak negative radial electric field to the strong positive one. This bifurcation of the turbulent transport is newly caused by the change of the damping rate of zonal flows. It is theoretically demonstrated that the damping rate of zonal flows governs the global confinement in toroidal plasmas. (author)
Electron current generated in a toroidal plasma on injection of high-energy neutrals
International Nuclear Information System (INIS)
Kolesnichenko, Ya.I.; Reznik, S.N.
1981-01-01
Problem of generation of electron current in toroidal plasma with a high-energy ion beam produced during neutral injection has been considered. The analysis was performed on the assumption that plasma is in the regime of rare collisions (banana regime) and ion beam velocity is considerably lower than thermal velocity of plasma ions. Formulae establishing the relation between beam current and electron current have been derived. It follows from them that toroidal affect considerably plasma current generated with the beam and under certain conditions result in changing this current direction in an area remoted from magne-- tic axis [ru
Effect of toroidal field ripple on the formation of internal transport barriers
Energy Technology Data Exchange (ETDEWEB)
Vries, P C de; Hawkes, N C; Challis, C D; Andrew, Y; Beurskens, M; Brix, M; Giroud, C; Zastrow, K-D [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Joffrin, E [EFDA-JET CSU, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Litaudon, X [Association EURATOM-CEA, DSM/DFRC, CEA Cadarache, 13108, St Paul lez Durance (France); Brzozowski, J; Johnson, T [Association EURATOM-VR, Fusion Plasma Physics, EES, KTH, Stockholm (Sweden); Crombe, K [Department of Applied Physics, Ghent University, Ghent (Belgium); Hobirk, J [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, 85748 Garching (Germany); Loennroth, J; Salmi, A [Association Euratom-Tekes, Helsinki University of Technology, PO Box 4100, 02015 TKK (Finland); Tala, T [Association Euratom-Tekes, VTT, PO Box 1000, 02044 VTT (Finland); Yavorskij, V [Institute for Theoretical Physics, Association EURATOM-OEAW, University of Innsbruck (Austria)], E-mail: Peter.de.Vries@jet.uk
2008-06-15
The effect of a toroidal field (TF) ripple on the formation and performance of internal transport barriers (ITBs) has been studied in JET. It was found that the TF ripple had a profound effect on the toroidal plasma rotation. An increased TF ripple up to {delta} = 1% led to a lower rotation and reduced the rotational shear in the region where the ITBs were formed. ITB triggering events were observed in all cases and it is thought that the rotational shear may be less important for this process than, for example, the q-profile. However, the increase in the pressure gradient following the ITB trigger was reduced in discharges with a larger TF ripple and consequently a lower rotational shear. This suggests that toroidal rotation and its shear play a role in the growth of the ITB once it has been triggered.
Physical properties of compact toroids generated by a coaxial source
Energy Technology Data Exchange (ETDEWEB)
Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; McKenna, K.F.; Platts, D.A.; Sherwood, A.R.
1980-01-01
In the CTX experiments we have been studying CTs generated with a magnetized coaxial plasma gun. CTs have been generated in prolate and oblate cylindrically symmetric metallic flux conservers. The plasma and magnetic field properties are studied through the use of magnetic probes, Thomson scattering, interferometry, and spectroscopy.
System and method for generating steady state confining current for a toroidal plasma fusion reactor
International Nuclear Information System (INIS)
Fisch, N.J.
1981-01-01
A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave rf energy is injected into said plasma to establish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected rf energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected rf energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range delta . The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width delta in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated in the plasma
System and method for generating steady state confining current for a toroidal plasma fusion reactor
International Nuclear Information System (INIS)
Bers, A.
1981-01-01
A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave rf energy is injected into said plasma to estalish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected rf energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected rf energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range delta . The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width delta in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated inthe plasma
Resistive toroidal stability of internal kink modes in circular and shaped tokamaks
International Nuclear Information System (INIS)
Bondeson, A.; Luetjens, H.; Vlad, G.
1991-12-01
The linear resistive magnetohydrodynamical (MHD) stability of the n=1 internal kink mode in tokamaks is studied by toroidal computations. The stabilizing influence of small aspect ratio is confirmed, but it is found that shaping of the cross section influences the internal kink mode significantly. For finite pressure and small resistivity, curvature effects at the q=1 surface make the stability sensitively dependent on shape, and ellipticity (including JET shape) is destabilizing. Only a very restricted set of finite pressure equilibria is completely stable for q 0 <1. A typical result is that the resistive kink mode is slowed down by toroidal effects to a weak tearing/resistive interchange mode. It is suggested that weak resistive instabilities are stabilized during the ramp phase of the sawteeth by effects not included in the linear resistive MHD model. Possible mechanisms for triggering a sawtooth crash are discussed. (author) 18 figs., 34 refs
International Nuclear Information System (INIS)
Kalsi, S.S.; Lousteau, D.C.; Miller, J.R.
1987-01-01
The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Europe, Japan, the Union of Soviet Socialist Republics (USSR), and the United States. This paper describes a magnetic and mechanical design methodology for toroidal field (TF) coils that employs Nb/sub 3/Sn superconductor technology. Coil winding is sized by using conductor concepts developed for the US TIBER concept. The nuclear heating generated during operation is removed from the windings by helium flowing through the conductor. The heat in the coil case is removed through a separate cooling circuit operating at approximately 20 K. Manifold concepts are presented for the complete coil cooling system. Also included are concepts for the coil structural arrangement. The effects of in-plane and out-of-plane loads are included in the design considerations for the windings and case. Concepts are presented for reacting these loads with a minimum amount of additional structural material. Concepts discussed in this paper could be considered for the ITER TF coils. 6 refs., 5 figs., 1 tab
Four giga joule flywheel motor-generator for JT-60 toroidal field coil power supply system
International Nuclear Information System (INIS)
Matsukawa, T.; Kanke, M.; Shimada, R.; Yoshida, Y.; Yamashita, K.; Nakayama, T.
1986-01-01
A fusion test reactor often needs motor-generators as a power source in order to reduce disturbances to utility lines. The toroidal field coil power supply system of JT-60 also adopted a motor-generator for this purpose. The motor-generator started operation in April, 1985 at Japan Atomic Energy Research Institute together with the whole system. The motor-generator has several special features both electrically and mechanically. One electrical feature is that it is used as a pulse source of large current and power for periodic short-time duty. A mechanical feature is that a large flywheel is directly coupled to the motor-generator shaft and operated intermittently and at high speed. Therefore detailed investigations were carried out concerning constitution, characteristics as well as the coordination with the system performance. This paper describes the outlines of the flywheel motor-generator and discusses several topics
International Nuclear Information System (INIS)
Tani, Takashi; Nakanishi, Yuji; Horita, Tsuyoshi; Kawase, Chiharu; Oyabu, Isao; Kishimoto, Takeshi.
1996-01-01
Mitsubishi Electric has delivered the world's largest DC generator for the toroidal field coil power supply of the JFT-2M Tokamak at the Japan Atomic Energy Research Institute. The unit rotates at 225 or 460 rpm, providing a maximum rated output of 2,700 V, 19,000 A and 51.3 MW. The toroidal field is a DC field, so use of a DC generator permits a simpler design consuming less floor space than an AC drive system. The generator was manufactured following extensive studies on commutation, mechanical strength and insulation. (author)
Compact toroids generated by a magnetized coaxial source in the CTX experiment
International Nuclear Information System (INIS)
Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.
1981-01-01
Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 μs for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10 14 cm -3 for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2
Compact toroids generated by a magnetized coaxial source in the CTX experiment
Energy Technology Data Exchange (ETDEWEB)
Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.
1981-01-01
Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 ..mu..s for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10/sup 14/ cm/sup -3/ for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2.
International Nuclear Information System (INIS)
Gibson, C.R.; Miller, J.R.
1988-01-01
This paper analyzes the effect of transverse loading on a cable-in-conduit conductor which has been proposed for the toroidal field coils of the International Thermonuclear Experimental Reactor. The primary components of this conductor are a loose cable of superconducting wires, a thin-wall tube for helium containment, and a U-shaped structural channel. A method is given where the geometry of this conductor can be optimized for a given set of operating conditions. It is shown, using finite-element modeling, that the structural channel is effective in supporting loads due to transverse forces and internal pressure. In addition, it is shown that the superconducting cable is effectively shielded from external transverse loads that might otherwise degrade its current carrying capacity. 10 refs., 10 figs., 3 tabs
Stable confinement of toroidal electron plasma in an internal conductor device Prototype-Ring Trap
International Nuclear Information System (INIS)
Saitoh, H.; Yoshida, Z.; Watanabe, S.
2005-01-01
A pure electron plasma has been produced in an internal conductor device Prototype-Ring Trap (Proto-RT). The temporal evolution of the electron plasma was investigated by the measurement of electrostatic fluctuations. Stable confinement was realized when the potential profile adjusted to match the magnetic surfaces. The confinement time varies as a function of the magnetic field strength and the neutral gas pressure, and is comparable to the diffusion time of electrons determined by the classical collisions with neutral gas. Although the addition of a toroidal magnetic field stabilized the electrostatic fluctuation of the plasma, the effects of the magnetic shear shortened the stable confinement time, possibly because of the obstacles of coil support structures
International Nuclear Information System (INIS)
Cheever, D.; Ihloff, E.; Kelsey, J.; Kolster, H.; Meitanis, N.; Milner, R.; Shinozaki, A.; Tsentalovich, E.; Zwart, T.; Ziskin, V.; Xiao, Y.; Zhang, C.
2006-01-01
A polarized hydrogen/deuterium internal gas target has been constructed and operated at the internal target region of the South Hall Ring (SHR) of the MIT-Bates Linear Accelerator Center to carry out measurements of spin-dependent electron scattering at 850MeV. The target used an Atomic Beam Source (ABS) to inject a flux of highly polarized atoms into a thin-walled, coated storage cell. The polarization of the electron beam was determined using a Compton laser backscattering polarimeter. The target polarization was determined using well-known nuclear reactions. The ABS and storage cell were embedded in the Bates Large Acceptance Toroidal Spectrometer (BLAST), which was used to detect scattered particles from the electron-target interactions. The target has been designed to rapidly (∼8h) switch operation from hydrogen to deuterium. Further, this target was the first to be operated inside a magnetic spectrometer in the presence of a magnetic field exceeding 2kG. An ABS intensity 2.5x10 16 at/s and a high polarization (∼70%) inside the storage cell have been achieved. The details of the target design and construction are described here and the performance over an 18 month period is reported
Initial Results of the SSPX Transient Internal Probe System for Measuring Toroidal Field Profiles
Holcomb, C. T.; Jarboe, T. R.; Mattick, A. T.; Hill, D. N.; McLean, H. S.; Wood, R. D.; Cellamare, V.
2000-10-01
Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. The Sustained Spheromak Physics Experiment (SSPX) is using a field profile diagnostic called the Transient Internal Probe (TIP). TIP consists of a verdet-glass bullet that is used to measure the magnetic field by Faraday rotation. This probe is shot through the spheromak by a light gas gun at speeds near 2 km/s. An argon laser is aligned along the path of the probe. The light passes through the probe and is retro-reflected to an ellipsometer that measures the change in polarization angle. The measurement is spatially resolved down to the probes’ 1 cm length to within 15 Gauss. Initial testing results are given. This and future data will be used to determine the field profile for equilibrium reconstruction. TIP can also be used in conjunction with wall probes to map out toroidal mode amplitudes and phases internally. This work was performed under the auspices of US DOE by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.
International Nuclear Information System (INIS)
Bussac, M.N.; Pellat, R.; Edery, D.; Soule, J.L.
1976-01-01
A linear analysis is presented of the toroidal coupling between the internal resistive modes (m=1, n=1) and (m=2, n=1) in the Tokomak with circular cross sections. One includes the resistive and diamagnetic effects in the singular layers where the safety factor q takes respectively the values one and two. By expanding the MHD equations in powers of epsilon, the local inverse of the aspect ratio, one obtains a system of two coupled equations for the harmonic amplitudes. When the shear is finite on q=1, the toroidal coupling is negligible. In the opposite limit, one can explain: the experimental behaviour of the (m=1, n=1) mode before the internal disruption; the simultaneous observation of the modes (m=1, n=1) and [de
International Nuclear Information System (INIS)
Kerns, J.A.; Wong, R.L.
1989-01-01
The toroidal field (TF) coils in the International Thermonuclear Experimental Reactor (ITER) will operate with varying heat loads generated by ac losses and nuclear heating. The total heat load is estimated to be 2 kW per TF coil under normal operation and can be higher for different operating scenarios. Ac losses are caused by ramping the poloidal field (PF) for plasma initiation, burn, and shutdown; nuclear heating results from neutrons that penetrate into the coil past the shield. Present methods to reduce or eliminate these losses lead to larger and more expensive machines, which are unacceptable with today's budget constraints. A suitable solution is to design superconductors that operate with high heat loads. The cable-in-conduit conductor (CICC) can operate with high heat loads. One CICC design is analyzed for its thermal performance using two computer codes developed at LLNL. One code calculates the steady state flow conditions along the flow path, while the other calculates the transient conditions in the flow. We have used these codes to analyze the superconductor performance during the burn phase of the ITER plasma. The results of these analyses give insight to the choice of flow rate on superconductor performance. 4 refs., 5 figs
International Nuclear Information System (INIS)
Smith, R.A.
1975-06-01
The structural analysis of toroidal field coils in Tokamak fusion machines can be performed with the finite element method. This technique has been employed for design evaluations of toroidal field coils on the Princeton Large Torus (PLT), the Poloidal Diverter Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR). The application of the finite element method can be simplified with computer programs that are used to generate the input data for the finite element code. There are three areas of data input where significant automation can be provided by supplementary computer codes. These concern the definition of geometry by a node point mesh, the definition of the finite elements from the geometric node points, and the definition of the node point force/displacement boundary conditions. The node point forces in a model of a toroidal field coil are computed from the vector cross product of the coil current and the magnetic field. The computer programs named PDXNODE and ELEMENT are described. The program PDXNODE generates the geometric node points of a finite element model for a toroidal field coil. The program ELEMENT defines the finite elements of the model from the node points and from material property considerations. The program descriptions include input requirements, the output, the program logic, the methods of generating complex geometries with multiple runs, computational time and computer compatibility. The output format of PDXNODE and ELEMENT make them compatible with PDXFORC and two general purpose finite element computer codes: (ANSYS) the Engineering Analysis System written by the Swanson Analysis Systems, Inc., and (WECAN) the Westinghouse Electric Computer Analysis general purpose finite element program. The Fortran listings of PDXNODE and ELEMENT are provided
Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines
Energy Technology Data Exchange (ETDEWEB)
Misguich, J.H.; Reuss, J.D. [Association Euratom-CEA sur la Fusion, CEA/DSM/DRFC, 13 - Saint Paul lez Durance (France); Constantinescu, D.; Steinbrecher, G. [Association Euratom-N.A.S.T.I., Dept. of Physics, University of Craiova (Romania); Vlad, M.; Spineanu, F. [Association Euratom-N.A.S.T.I., National Institute of Laser, Plasma and Radiation Physics, Bucharest (Romania); Weyssow, B.; Balescu, R. [Association Euratom-Etat Belge sur la Fusion, Universite Libre de Bruxelles (Belgium)
2002-02-01
Internal transport barriers (ITB's) observed in tokamaks are described by a purely magnetic approach. Magnetic line motion in toroidal geometry with broken magnetic surfaces is studied from a previously derived Hamiltonian map in situation of incomplete chaos. This appears to reproduce in a realistic way the main features of a tokamak, for a given safety factor profile and in terms of a single parameter L representing the amplitude of the magnetic perturbation. New results are given concerning the Shafranov shift as function of L. For small values of L, closed magnetic surfaces exist (KAM tori) and island chains begin to appear on rational surfaces for higher values of L, with chaotic zones around hyperbolic points, as expected. Single trajectories of magnetic line motion indicate the persistence of a central protected plasma core, surrounded by a chaotic shell enclosed in a double-sided transport barrier. Magnetic lines which succeed to escape across this barrier begin to wander in a wide chaotic sea extending up to a very robust barrier (as long as L{<=}1). For values of L{>=}1, above the escape threshold, most magnetic lines succeed to escape out of the external barrier which has become a permeable Cantorus. Statistical analysis of a large number of trajectories, representing the evolution of a bunch of magnetic lines, indicate that the flux variable {psi} asymptotically grows in a diffuse manner as (L{sup 2}t) with a L{sup 2} scaling as expected, but that the average radial position r{sub m}(t) asymptotically grows as (L{sup 2}t){sup 1/4} while the mean square displacement around this average radius asymptotically grows in a sub-diffusive manner as (L{sup 2}t){sup 1/2}. This result shows the slower dispersion in the present incomplete chaotic regime, which is different from the usual quasilinear diffusion in completely chaotic situations. For physical times t{sub {phi}} of the order of the escape time defined by x{sub m}(t{sub {phi}}) {approx}1, the motion
Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines
International Nuclear Information System (INIS)
Misguich, J.H.; Reuss, J.D.; Constantinescu, D.; Steinbrecher, G.; Vlad, M.; Spineanu, F.; Weyssow, B.; Balescu, R.
2002-02-01
Internal transport barriers (ITB's) observed in tokamaks are described by a purely magnetic approach. Magnetic line motion in toroidal geometry with broken magnetic surfaces is studied from a previously derived Hamiltonian map in situation of incomplete chaos. This appears to reproduce in a realistic way the main features of a tokamak, for a given safety factor profile and in terms of a single parameter L representing the amplitude of the magnetic perturbation. New results are given concerning the Shafranov shift as function of L. For small values of L, closed magnetic surfaces exist (KAM tori) and island chains begin to appear on rational surfaces for higher values of L, with chaotic zones around hyperbolic points, as expected. Single trajectories of magnetic line motion indicate the persistence of a central protected plasma core, surrounded by a chaotic shell enclosed in a double-sided transport barrier. Magnetic lines which succeed to escape across this barrier begin to wander in a wide chaotic sea extending up to a very robust barrier (as long as L≤1). For values of L≥1, above the escape threshold, most magnetic lines succeed to escape out of the external barrier which has become a permeable Cantorus. Statistical analysis of a large number of trajectories, representing the evolution of a bunch of magnetic lines, indicate that the flux variable ψ asymptotically grows in a diffuse manner as (L 2 t) with a L 2 scaling as expected, but that the average radial position r m (t) asymptotically grows as (L 2 t) 1/4 while the mean square displacement around this average radius asymptotically grows in a sub-diffusive manner as (L 2 t) 1/2 . This result shows the slower dispersion in the present incomplete chaotic regime, which is different from the usual quasilinear diffusion in completely chaotic situations. For physical times t φ of the order of the escape time defined by x m (t φ ) ∼1, the motion appears to be super-diffusive, however, but less dangerous than
Kuiroukidis, Ap.; Throumoulopoulos, G. N.
2015-08-01
We construct nonlinear toroidal equilibria of fixed diverted boundary shaping with reversed magnetic shear and flows parallel to the magnetic field. The equilibria have hole-like current density and the reversed magnetic shear increases as the equilibrium nonlinearity becomes stronger. Also, application of a sufficient condition for linear stability implies that the stability is improved as the equilibrium nonlinearity correlated to the reversed magnetic shear gets stronger with a weaker stabilizing contribution from the flow. These results indicate synergetic stabilizing effects of reversed magnetic shear, equilibrium nonlinearity and flow in the establishment of Internal Transport Barriers (ITBs).
International Nuclear Information System (INIS)
Ware, A.S.; Diamond, P.H.
1993-01-01
The effects of a poloidally asymmetric ionization source on both dissipative toroidal drift wave stability and the generation of mean sheared parallel flow are examined. The first part of this work extends the development of a local model of ionization-driven drift wave turbulence [Phys. Fluids B 4, 877 (1992)] to include the effects of magnetic shear and poloidal source asymmetry, as well as poloidal mode coupling due to both magnetic drifts and the source asymmetry. Numerical and analytic investigation confirm that ionization effects can destabilize collisional toroidal drift waves. However, the mode structure is determined primarily by the magnetic drifts, and is not overly effected by the poloidal source asymmetry. The ionization source drives a purely inward particle flux, which can explain the anomalously rapid uptake of particles which occurs in response to gas puffing. In the second part of this work, the role poloidal asymmetries in both the source and turbulent particle diffusion play in the generation of sheared mean parallel flow is examined. Analysis indicates that predictions of sonic parallel shear flow [v parallel (r)∼c s ] are an unphysical result of the assumption of purely parallel flow (i.e., v perpendicular =0) and the neglect of turbulent parallel momentum transport. Results indicate that the flow produced is subcritical to the parallel shear flow instability when diamagnetic effects are properly considered
Lubis, Asnawi
2014-01-01
In under to reduce the Public Service Obligation (PSO) on oil fuel, the goverment of Indonesia initianted a program of conversion of oil fuel into gas fuel (BBG) for passenger cars. In supporting this program, it is required to develop the component of combustion system. One of the components is strorage tank for BBG that must be carefully designed to avoid burst type failure. Based on previous research, a toroidal tank can withstand higher limit pressure than the PERTAMINA LPG 3kg storage t...
2009-01-01
three axis fluxgate magnetometer , CMOS sun and star sensors, and a Kalman filter. The work and tasks that have been accomplished on the TOROID... magnetometer . The problem was found to be a missing ferrite bead which connects the 12V power supply to the op-amps which are used to appropriately...establish an overall operational timeline for TOROID. Testing and calibration was performed on the three-axis magnetometer which is primary attitude
International Nuclear Information System (INIS)
1974-11-01
The lectures of a Varenna Summer School about the theme Instabilities and Confinement in toroidal Plasmas are given. The topics included are: high-beta toroidal pinches, non-MHD instabilities and anomalous transport, analogy between turbulent transfer in velocity space and plasma collisioned transport in real space, the magnetohydrodynamic approach of plasma confinement in closed magnetic configurations, properties of isodynamical equilibrium configurations and their generalization, transport theory for toroidal plasmas, plasma physics, low-β toroidal machines, the neoclassical theory of transit time magnetic pumping, radio frequency heating of toroidal plasmas, plasma heating at lower hybrid frequency, RF-plasma heating with L-structures, numerical simulation, dynamical stabilization of low frequency waves in inhomogeneous plasmas, dynamic and feedback stabilization of plasmas and problems with nuclear fusion reactors
Energy Technology Data Exchange (ETDEWEB)
Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Tritz, Kevin [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
2013-07-15
Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.
International Nuclear Information System (INIS)
Slack, D.S.
1989-01-01
The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Japan, the European Community, the Union of the Soviet Union, and the United States. This paper examines the effects of a quench within the toroidal field (TF) coils based on current ITER design. It is a preliminary, rough analysis. Its intent is to assist ITER designers while more accurate computer codes are being developed and to provide a check against these more rigorous solutions. Rigorous solutions to the quench problem are very complex involving three-dimensional heat transfer, extreme changes in heat capacities and copper resistivity, and varying flow dynamics within the conductors. This analysis addresses all these factors in an approximate way. The result is much less accurate than a rigorous analysis. Results here could be in error as much as 30 to 40 percent. However, it is believed that this paper can still be very useful to the coil designer. Coil pressures and temperatures vs time into a quench are presented. Rate of helium vent, energy deposition in the coil, and depletion of magnetic stored energy are also presented. Peak pressures are high (about 43 MPa). This is due to the very long vent path length (446 m), small hydraulic diameters, and high current densities associated with ITER's cable-in-conduit design. The effects of these pressures as well as the ability of the coil to be self protecting during a quench are discussed. 3 refs., 3 figs., 1 tab
International Nuclear Information System (INIS)
Bussac, M.N.; Pellat, R.; Edery, D.; Soule, J.L.
1977-01-01
A linear analysis is presented of the toroidal coupling between the internal resistive modes (m=1, n=1) and (m=2, n=1) in the tokamak with circular cross-section. The resistive and diamagnetic effects are included in the singular layers where the safety factor q takes respectively the values one and two. By expanding the MHD equations in powers of epsilon, the local inverse of the aspect ratio, a system of two coupled equations is obtained for the harmonic amplitudes. When the shear is finite on q=1 the toroidal coupling is negligible. In the opposite limit, one can explain (a) the experimental behaviour of the (m=1, n=1) mode before the internal disruption, and (b) the simultaneous observation of the modes (m=1, n=1) and (m=2, n=1) before the main disruption. (author)
International Nuclear Information System (INIS)
Kim, S. S.; Jhang, Hogun; Diamond, P. H.
2012-01-01
We study the interplay between intrinsic rotation and internal transport barrier (ITB) dynamics through the dynamic change of the parallel Reynolds stress. Global flux-driven gyrofluid simulations are used for this study. In particular, we investigate the role of parallel velocity gradient instability (PVGI) in the ITB formation and the back transition. It is found that the excitation of PVGI is followed by a change in the Reynolds stress which drives a momentum redistribution. This significantly influences E×B shear evolution and subsequent ITB dynamics. Nonlocal interactions among fluctuations are also observed during the PVGI excitation, resulting in turbulence suppression at the ITB.
Generation IV reactors: international projects
International Nuclear Information System (INIS)
Carre, F.; Fiorini, G.L.; Kupitz, J.; Depisch, F.; Hittner, D.
2003-01-01
Generation IV international forum (GIF) was initiated in 2000 by DOE (American department of energy) in order to promote nuclear energy in a long term view (2030). GIF has selected 6 concepts of reactors: 1) VHTR (very high temperature reactor system, 2) GHR (gas-cooled fast reactor system), 3) SFR (sodium-cooled fast reactor system, 4) SCWR (super-critical water-cooled reactor system), 5) LFR (lead-cooled fast reactor system), and 6) MFR (molten-salt reactor system). All these 6 reactor systems have been selected on criteria based on: - a better contribution to sustainable development (through their aptitude to produce hydrogen or other clean fuels, or to have a high energy conversion ratio...) - economic profitability, - safety and reliability, and - proliferation resistance. The 6 concepts of reactors are examined in the first article, the second article presents an overview of the results of the international project on innovative nuclear reactors and fuel cycles (INPRO) within IAEA. The project finished its first phase, called phase-IA. It has produced an outlook into the future role of nuclear energy and defined the need for innovation. The third article is dedicated to 2 international cooperations: MICANET and HTR-TN. The purpose of MICANET is to propose to the European Commission a research and development strategy in order to develop the assets of nuclear energy for the future. Future reactors are expected to be more multiple-purposes, more adaptable, safer than today, all these developments require funded and coordinated research programs. The aim of HTR-TN cooperation is to promote high temperature reactor systems, to develop them in a long term perspective and to define their limits in terms of burn-up and operating temperature. (A.C.)
International Nuclear Information System (INIS)
Canobbio, E.
1981-01-01
This paper reports on the 2nd Joint Grenoble-Varenna International Symposium on Heating in Toroidal Plasmas, held at Como, Italy, from the 3-12 September 1980. Important problems in relation to the different existing processes of heating. The plasma were identified and discussed. Among others, the main processes discussed were: a) neutral beam heating, b) ion-(electron)-cyclotron resonance heating, c) hybrid resonance and low frequency heating
International Nuclear Information System (INIS)
Knoepfel, H.; Mazzitelli, G.
1984-01-01
The article is a rather detailed report on the highlights in the area of the ''Heating in toroidal plasmas'', as derived from the presentations and discussions at the international symposium with the same name, held in Rome, March 1984. The symposium covered both the physics (experiments and theory) and technology of toroidal fusion plasma heating. Both large fusion devices (either already in operation or near completion) requiring auxiliary heating systems at the level of tens of megawatts, as well as physics of their heating processes and their induced side effects (as studied on smaller devices), received attention. Substantial progress was reported on the broad front of auxiliary plasma heating and Ohmic heating. The presentation of the main conclusions of the symposium is divided under the following topics: neutral-beam heating, Alfven wave heating, ion cyclotron heating, lower hybrid heating, RF current drive, electron cyclotron heating, Ohmic heating and special contributions
System for calibration of SPEAR transport line toroids
International Nuclear Information System (INIS)
Huang, T.V.; Smith, H.; Crook, K.
1977-01-01
A one nanosecond pulse generator was developed for calibration of the intensity monitors (toroids) in the SPEAR transport lines. The generator, located at the toroid, is simple, low cost and resistant to radiation. The generator and its connection to the standard SLAC toroid calibration system are described
The changing face of international power generation
Energy Technology Data Exchange (ETDEWEB)
Lindsay, I. [World Energy Council, London (United Kingdom)
1997-12-31
The author limits his remarks to a discussion of the international generator`s marketplace, especially aimed at the developing countries. He discusses future global electricity demand, generating capacity build, its financing issues, and to the commercial generating opportunities which now abound outside the US.
Tunable plasmonic toroidal terahertz metamodulator
Gerislioglu, Burak; Ahmadivand, Arash; Pala, Nezih
2018-04-01
Optical modulators are essential and strategic parts of micro- and nanophotonic circuits to encode electro-optical signals in the optical domain. Here, by using arrays of multipixel toroidal plasmonic terahertz (THz) metamolecules, we developed a functional plasmonic metamodulator with high efficiency and tunability. Technically, the dynamic toroidal dipole induces nonradiating charge-current arrangements leading to have an exquisite role in defining the inherent spectral features of various materials. By categorizing in a different family of multipoles far from the traditional electromagnetic multipoles, the toroidal dipole corresponds to poloidal currents flowing on the surface of a closed-loop torus. Utilizing the sensitivity of the optically driven toroidal momentum to the incident THz beam power and by employing both numerical tools and experimental analysis, we systematically studied the spectral response of the proposed THz plasmonic metadevice. In this Rapid Communication, we uncover a correlation between the existence and the excitation of the toroidal response and the incident beam power. This mechanism is employed to develop THz toroidal metamodulators with a strong potential to be employed for practical advanced and next-generation communication, filtering, and routing applications.
Compact toroid refueling of reactors
International Nuclear Information System (INIS)
Gouge, M.J.; Hogan, J.T.; Milora, S.L.; Thomas, C.E.
1988-04-01
The feasibility of refueling fusion reactors and devices such as the International Thermonuclear Engineering Reactor (ITER) with high-velocity compact toroids is investigated. For reactors with reasonable limits on recirculating power, it is concluded that the concept is not economically feasible. For typical ITER designs, the compact toroid fueling requires about 15 MW of electrical power, with about 5 MW of thermal power deposited in the plasma. At these power levels, ideal ignition (Q = ∞) is not possible, even for short-pulse burns. The pulsed power requirements for this technology are substantial. 6 ref., 1 figs
Third international seminar on horizontal steam generators
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-12-31
The Third International Seminar on Horizontal Steam Generators held on October 18-20, 1994 in Lappeenranta, consisted of six sessions dealing with the topics: thermal hydraulic experiments and analyses, primary collector integrity, management of primary-to-secondary leakage accidents, feedwater collector replacement and discussion of VVER-440 steam generator safety issues.
Third international seminar on horizontal steam generators
International Nuclear Information System (INIS)
1995-01-01
The Third International Seminar on Horizontal Steam Generators held on October 18-20, 1994 in Lappeenranta, consisted of six sessions dealing with the topics: thermal hydraulic experiments and analyses, primary collector integrity, management of primary-to-secondary leakage accidents, feedwater collector replacement and discussion of VVER-440 steam generator safety issues
Third international seminar on horizontal steam generators
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-12-31
The Third International Seminar on Horizontal Steam Generators held on October 18-20, 1994 in Lappeenranta, consisted of six sessions dealing with the topics: thermal hydraulic experiments and analyses, primary collector integrity, management of primary-to-secondary leakage accidents, feedwater collector replacement and discussion of VVER-440 steam generator safety issues.
Toroidal helical quartz forming machine
International Nuclear Information System (INIS)
Hanks, K.W.; Cole, T.R.
1977-01-01
The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed
Fourth international seminar on horizontal steam generators
Energy Technology Data Exchange (ETDEWEB)
Tuomisto, H. [ed.] [IVO Group, Vantaa (Finland); Purhonen, H. [ed.] [VTT, Espoo (Finland); Kouhia, V. [ed.] [Lappeenranta Univ. of Technology (Finland)
1997-12-31
The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.
Fourth international seminar on horizontal steam generators
Energy Technology Data Exchange (ETDEWEB)
Tuomisto, H [ed.; IVO Group, Vantaa (Finland); Purhonen, H [ed.; VTT, Espoo (Finland); Kouhia, V [ed.; Lappeenranta Univ. of Technology (Finland)
1998-12-31
The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.
Fourth international seminar on horizontal steam generators
International Nuclear Information System (INIS)
Tuomisto, H.; Purhonen, H.; Kouhia, V.
1997-01-01
The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries
Generation 4 International Forum. 2007 annual report
International Nuclear Information System (INIS)
2007-01-01
This annual report is the first to be issued by GIF (Generation IV International Forum). It summarizes the GIF goals and accomplishments throughout 2007, describes its membership and organization, and provides an overview of its cooperation with other international endeavors for the development of nuclear energy. Future editions will focus on technical progress. Chapter 2 provides an overview on the goals of Generation IV nuclear energy systems and outlines the main characteristics of the six systems selected for joint development by GIF (VHTR - Very High Temperature Reactor; SFR - Sodium-cooled Fast Reactor; SCWR - Super-Critical Water cooled Reactor; GFR - Gas-cooled Fast Reactor; LFR - Lead-cooled Fast Reactor; and MSR - Molten Salt Reactor). Chapter 3 describes the membership and organization of the GIF, the structure of its cooperative research and development (R-D) arrangements, and the status of Member participation in these arrangements. Chapter 4 summarizes the R-D plans and achievements of the Forum until now. It highlights the R-D challenges facing the teams developing Generation IV systems and the major milestones towards the development of these systems. It also describes the progress made regarding the development of methodologies for assessing Generation IV systems with respect to the established goals. Chapter 5 reviews other major international collaborative projects in the field of nuclear energy and explains how the GIF interacts and cooperates with them. Bibliographical references are provided in each chapter in order to facilitate access to public information about the GIF objectives, goals and outcomes
Generation 4 International Forum. 2008 annual report
International Nuclear Information System (INIS)
2008-01-01
This 2008 Annual Report is the second annual report issued by GIF (Generation IV International Forum). It provides an update on the GIF organization, membership, and participation in research and development (R-D) projects for each Generation IV system. It summarizes the milestones for development of each system and progress of the R-D toward their accomplishment. Finally, it includes a brief description of the cooperation between GIF and other international endeavors for the development of nuclear energy. Chapter 2 describes the membership and organization of the GIF, the structure of its cooperative research and development arrangements, and the status of Member participation in those arrangements. Chapter 3 provides a summary of the GIF R-D plans, and its activities and achievements during 2008. It highlights the R-D challenges facing the teams developing Generation IV systems and the major milestones towards the development of these systems. It also describes the progress made regarding the development of methodologies for assessing Generation IV systems with respect to the established goals of GIF. Chapter 4 reviews other major international collaborative projects in the field of nuclear energy and explains how the GIF interacts and cooperates with them. Appendix 1 provides an overview on the goals of Generation IV nuclear energy systems and outlines the main characteristics of the six systems selected for joint development by GIF. The list of abbreviations and acronyms given at the end of the report defines terms used in the various chapters including various nuclear energy systems and international programs referred to in connection with GIF R-D activities. Some bibliographical references are given in order to facilitate access to public information about R-D progress and achievements on specific technical issues for GIF systems
Experimental studies of compact toroids
International Nuclear Information System (INIS)
1991-01-01
The Berkeley Compact Toroid Experiment (BCTX) device is a plasma device with a Marshall-gun generated, low aspect ratio toroidal plasma. The device is capable of producing spheromak-type discharges and may, with some modification, produce low-aspect ratio tokamak configurations. A unique aspect of this experimenal devie is its large lower hybrid (LH) heating system, which consists of two 450MHz klystron tubes generating 20 megawatts each into a brambilla-type launching structure. Successful operation with one klystron at virtually full power (18 MW) has been accomplished with 110 μs pulse length. A second klystron is currently installed in its socket and magnet but has not been added to the RF drive system. This report describes current activities and accomplishments and describes the anticipated results of next year's activity
Generation 4 International Forum. 2009 annual report
International Nuclear Information System (INIS)
2009-01-01
This 2009 Annual Report is the third annual report issued by GIF (Generation 4. International Forum). It includes 3 chapters in addition to an introduction plus 4 appendices, as follows. Chapter 2 describes the membership and organization of GIF, the structure of its cooperative research and development arrangements as well as the status of Members' participation in such arrangements. Chapter 3 summarizes GIF research and development plans, activities and achievements during 2009. It highlights the scientific and technical challenges facing the teams developing Generation IV systems and the major milestones towards the development of these systems. It also describes the progress made on the development of methodologies for assessing Generation IV systems with respect to the established goals of GIF. Chapter 4 reviews the cooperation between GIF and other international programs dealing with the development of nuclear energy. Appendix 1 provides an overview on the goals of Generation IV nuclear energy systems and an outline of the main characteristics of the six systems selected for joint development by GIF. Appendix 2 presents the objectives that have been set for the various System Steering Committees and the associated Project Management Boards for the next 5 years. Appendix 3 reproduces the Table of Contents of the Proceedings from the GIF Symposium held in Paris (France) in 2009. Appendix 4 provides a list of abbreviations and acronyms (with the corresponding definitions) which are used in this report or are relevant to GIF activities
On the stabilization of toroidal pinches by finite larmor radius effects and toroidal magnetic field
International Nuclear Information System (INIS)
Singh, R.; Weiland, J.
1989-01-01
The radial eigenvalue problem for internal modes in a large aspect ratio toriodal pinch has been solved. A particularly stable regime for a weak but nonzero toroidal magnetic field has been found. (31 refs.)
Energy Technology Data Exchange (ETDEWEB)
Kim, Kwangmin, E-mail: kwangmin81@gmail.com [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Go, Byeong-Soo; Sung, Hae-Jin; Park, Hea-chul; Kim, Seokho [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Lee, Sangjin [Uiduk University, Gyeongju 780-713 (Korea, Republic of); Jin, Yoon-Su; Oh, Yunsang [Vector Fields Korea Inc., Pohang 790-834 (Korea, Republic of); Park, Minwon [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Yu, In-Keun, E-mail: yuik@changwon.ac.kr [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of)
2014-09-15
Highlights: • The authors designed and fabricated a D-shape coil based toroid-type HTS DC reactor using 2G GdBCO HTS wires. • The toroid-type magnet consisted of 30 D-shape double pancake coil (DDC)s. The total length of the wire was 2.32 km. • The conduction cooling method was adopted for reactor magnet cooling. • The maximum cooling temperature of reactor magnet is 5.5 K. • The inductance was 408 mH in the steady-state condition (300 A operating). - Abstract: This paper describes the design specifications and performance of a real toroid-type high temperature superconducting (HTS) DC reactor. The HTS DC reactor was designed using 2G HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The target inductance of the HTS DC reactor was 400 mH. The expected operating temperature was under 20 K. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. Performances of the toroid-type HTS DC reactor were analyzed through experiments conducted under the steady-state and charge conditions. The fundamental design specifications and the data obtained from this research will be applied to the design of a commercial-type HTS DC reactor.
Hedberg V
On the 15th of June 2001 the EB approved a new conceptual design for the toroid shield. In the old design, shown in the left part of the figure above, the moderator part of the shielding (JTV) was situated both in the warm and cold areas of the forward toroid. It consisted both of rings of polyethylene and hundreds of blocks of polyethylene (or an epoxy resin) inside the toroid vacuum vessel. In the new design, shown to the right in the figure above, only the rings remain inside the toroid. To compensate for the loss of moderator in the toroid, the copper plug (JTT) has been reduced in radius so that a layer of borated polyethylene can be placed around it (see figure below). The new design gives significant cost-savings and is easier to produce in the tight time schedule of the forward toroid. Since the amount of copper is reduced the weight that has to be carried by the toroid is also reduced. Outgassing into the toroid vacuum was a potential problem in the old design and this is now avoided. The main ...
2002-01-01
Because of its exceptional size, it was not feasible to assemble and test the Barrel Toroid - made of eight coils - as an integrated toroid on the surface, prior to its final installation underground in LHC interaction point 1. It was therefore decided to test these eight coils individually in a dedicated test facility.
Alfven continuum with toroidicity
International Nuclear Information System (INIS)
Riyopoulos, S.; Mahajan, S.M.
1985-06-01
The symmetry property of the MHD wave propagation operator is utilized to express the toroidal eigenmodes as a superposition of the mutually orthogonal cylindrical modes. Because of the degeneracy among cylindrical modes with the same frequency but resonant surfaces of different helicity the toroidal perturbation produces a zeroth order mixing of the above modes. The toroidal eigenmodes of frequency ω 0 2 have multiple resonant surfaces, with each surface shifted relative to its cylindrical position and carrying a multispectral content. Thus a single helicity toroidal antenna of frequency ω 0 couples strongly to all different helicity resonant surfaces with matching local Alfven frequency. Zeroth order coupling between modes in the continuum and global Alfven modes also results from toroidicity and degeneracy. Our perturbation technique is the MHD counterpart of the quantum mechanical methods and is applicable through the entire range of the MHD spectrum
International Nuclear Information System (INIS)
Ikuta, Kazunari; Miyahara, Akira.
1983-06-01
The concept of the limiter-divertor proposed by Mirnov is extended to a toroidal limiter-divertor (which we call moving toroidal limiter) using the stream of ferromagnetic balls coated with a low Z materials such as plastics, graphite and ceramics. An important advantage of the use of the ferromagnetic materials would be possible soft landing of the balls on a catcher, provided that the temperature of the balls is below Curie point. Moreover, moving toroidal limiter would work as a protector of the first wall not only against the vertical movement of plasma ring but also against the violent inward motion driven by major disruption because the orbit of the ball in the case of moving toroidal limiter distributes over the small major radius side of the toroidal plasma. (author)
Samus Toroid Installation Fixture
Energy Technology Data Exchange (ETDEWEB)
Stredde, H.; /Fermilab
1990-06-27
The SAMUS (Small Angle Muon System) toroids have been designed and fabricated in the USSR and delivered to D0 ready for installation into the D0 detector. These toroids will be installed into the aperture of the EF's (End Toroids). The aperture in the EF's is 72-inch vertically and 66-inch horizontally. The Samus toroid is 70-inch vertically by 64-inch horizontally by 66-inch long and weighs approximately 38 tons. The Samus toroid has a 20-inch by 20-inch aperture in the center and it is through this aperture that the lift fixture must fit. The toroid must be 'threaded' through the EF aperture. Further, the Samus toroid coils are wound about the vertical portion of the aperture and thus limit the area where a lift fixture can make contact and not damage the coils. The fixture is designed to lift along a surface adjacent to the coils, but with clearance to the coil and with contact to the upper steel block of the toroid. The lift and installation will be done with the 50 ton crane at DO. The fixture was tested by lifting the Samus Toroid 2-inch off the floor and holding the weight for 10 minutes. Deflection was as predicted by the design calculations. Enclosed are sketches of the fixture and it relation to both Toroids (Samus and EF), along with hand calculations and an Finite Element Analysis. The PEA work was done by Kay Weber of the Accelerator Engineering Department.
Generation IV international forum 2002 - remarks
International Nuclear Information System (INIS)
Abraham, S.
2002-01-01
Analyses and forecasts underscore the important role of nuclear power in energy supply in the 21st century. Important aspects in this respect are the conservation of fossil resources, the protection of the world's climate, and the continuity of supply. Present 1st and 2nd generation nuclear power plants ensure an economical and technically mature electricity supply. Advanced systems offering, e.g., higher efficiency of fuel utilization, simplified systems technology, and advanced safety characteristics, can make available additional benefits in using nuclear power. Upon an initiative of the U.S. Department of Energy (DOE), ten countries combine their efforts in developing such reactor concepts in the Generation IV International Forum (GIF). Argentina, Brazil, Canada, France, Japan, South Africa, South Korea, Switzerland, the United Kingdom, and the United States pursue the common objective in GIF to identify suitable nuclear power systems and promote their development up to the envisaged readiness for construction in 2030. Besides technical and economic questions of nuclear power generation, also other aspects must be considered with a view to the future use of nuclear power. The particularly relevant issues, such as the management of radioactive waste, the intensification of research and development, and international cooperation, have been taken up by the Bush administration at an early point in time and have been, or will be, incorporated in practical solutions, as in the case of the Yucca Mountain repository project. (orig.)
Prospects for toroidal fusion reactors
International Nuclear Information System (INIS)
Sheffield, J.; Galambos, J.D.
1994-01-01
Work on the International Thermonuclear Experimental Reactor (ITER) tokamak has refined understanding of the realities of a deuterium-tritium (D-T) burning magnetic fusion reactor. An ITER-like tokamak reactor using ITER costs and performance would lead to a cost of electricity (COE) of about 130 mills/kWh. Advanced tokamak physics to be tested in the Toroidal Physics Experiment (TPX), coupled with moderate components in engineering, technology, and unit costs, should lead to a COE comparable with best existing fission systems around 60 mills/kWh. However, a larger unit size, ∼2000 MW(e), is favored for the fusion system. Alternative toroidal configurations to the conventional tokamak, such as the stellarator, reversed-field pinch, and field-reversed configuration, offer some potential advantage, but are less well developed, and have their own challenges
TFTR toroidal field coil design
International Nuclear Information System (INIS)
Smith, G.E.; Punchard, W.F.B.
1977-01-01
The design of the Tokamak Fusion Test Reactor (TFTR) Toroidal Field (TF) magnetic coils is described. The TF coil is a 44-turn, spiral-wound, two-pancake, water-cooled configuration which, at a coil current of 73.3 kiloamperes, produces a 5.2-Tesla field at a major radius of 2.48 meters. The magnetic coils are installed in titanium cases, which transmit the loads generated in the coils to the adjacent supporting structure. The TFTR utilizes 20 of these coils, positioned radially at 18 0 intervals, to provide the required toroidal field. Because it is very highly loaded and subject to tight volume constraints within the machine, the coil presents unique design problems. The TF coil requirements are summarized, the coil configuration is described, and the problems highlighted which have been encountered thus far in the coil design effort, together with the development tests which have been undertaken to verify the design
Generation 4 International Forum. 2014 Annual Report
International Nuclear Information System (INIS)
2015-01-01
This eighth edition of the Generation IV International Forum (GIF) Annual Report highlights the main achievements of the Forum in 2014, and in particular progress made in the collaborative RandD activities of the eleven existing project arrangements for the six GIF systems: the gas-cooled fast reactor, the sodium-cooled fast reactor, the supercritical-water-cooled reactor and the very-high-temperature reactor. Progress made under the memoranda of understanding for the lead-cooled fast reactor and the molten salt reactor is also reported. In May 2014, China joined the supercritical-water-cooled reactor system arrangement; and in October 2014, the project arrangement on system integration and assessment for the sodium-cooled fast reactor became effective. GIF also continued to develop safety design criteria and guidelines for the sodium-cooled fast reactor, and to engage with regulators on safety approaches for generation IV systems. Finally, GIF initiated an internal discussion on sustainability approaches to complement ongoing work on economics, safety, proliferation resistance and physical protection
International cost relations in electric power generation
International Nuclear Information System (INIS)
Schmitt, D.; Duengen, H.; Wilhelm, M.
1986-01-01
In spite of the fact that analyses of the cost of electric power generation as the result of international comparative evaluations are indisputably relevant, problems pending in connection with the costs of representative power plant technologies are of the methodological bind. German authors have hitherto also been failing to clear up and consider all aspects connected with the problems of data acquisition and the adequate interpretation of results. The analysis presented by the paper abstracted therefore aims at the following: 1) Systematization of the different categories of cost relevant in connection with international comparative evaluation. Classification into different categories of decision making and development of standards meeting the requirements of international comparative evaluation. 2) Calculation of relevant average financial costs of Western German, America and French fossil-fuel and nuclear power plants by means of adequate calculation models, that is the assessment of costs with regard to countries and power plant technologies which are relevant to the Federal Republic of Germany. 3) Analysis of the resulting differences and determinantal interpretation. (orig./UA) [de
Fifth CNS international steam generator conference
International Nuclear Information System (INIS)
2006-01-01
The Fifth CNS International Steam Generator Conference was held on November 26-29, 2006 in Toronto, Ontario, Canada. In contrast with other conferences which focus on specific aspects, this conference provided a wide ranging forum on nuclear steam generator technology from life-cycle management to inspection and maintenance, functional and structural performance characteristics to design architecture. The 5th conference has adopted the theme: 'Management of Real-Life Equipment Conditions and Solutions for the Future'. This theme is appropriate at a time of transition in the industry when plants are looking to optimize the performance of existing assets, prevent costly degradation and unavailability, while looking ahead for new steam generator investments in life-extension, replacements and new-build. More than 50 technical papers were presented in sessions that gave an insight to the scope: life management strategies; fouling, cleaning and chemistry; replacement strategies and new build design; materials degradation; condition assessment/fitness for service; inspection advancements and experience; and thermal hydraulic performance
Motion of a compact toroid inside a cylindrical flux conserver
Energy Technology Data Exchange (ETDEWEB)
Jarboe, T.R.; Henins, I.; Hoida, H.W.; Linford, R.K.; Marshall, J.; Platts, D.A.; Sherwood, A.R.
1980-10-13
Compact toroids have been generated in a cylindrical resistive flux conserver. They are observed to rotate so that their major axis is perpendicular to the axis of the flux conserver. Subsequently they remain stationary and their magnetic fields decay with a time constant of about 100 ..mu..s. This is the first observation of the predicted tipping mode and its saturation when no external fields are present. The compact toroids contain toroidal fields and are initially prolate in shape.
Motion of a compact toroid inside a cylindrical flux conserver
International Nuclear Information System (INIS)
Jarboe, T.R.; Henins, I.; Hoida, H.W.; Linford, R.K.; Marshall, J.; Platts, D.A.; Sherwood, A.R.
1980-01-01
Compact toroids have been generated in a cylindrical resistive flux conserver. They are observed to rotate so that their major axis is perpendicular to the axis of the flux conserver. Subsequently they remain stationary and their magnetic fields decay with a time constant of about 100 μs. This is the first observation of the predicted tipping mode and its saturation when no external fields are present. The compact toroids contain toroidal fields and are initially prolate in shape
Internal ultrasonic testing of steam generator tubes
International Nuclear Information System (INIS)
Furlan, J.; Soleille, G.; Chalaye, H.
1983-01-01
The ''in situ'' inspection of steam generator tubes uses generally Foucault currents before starting and along its life. This inspection aims at searching cracks and corrosion defects. The Foucault current method is quite badly adapted to ''closed crack'' detection, for it doesn't introduce neither resistivity or magnetic permeability variation, or lack of matter. More, it is sensible to the magnetic properties of the tube itself and to its environment (tubular or support plates). It is why, this first systematic inspection has to be completed by an ultrasonic one allowing to bring new elements in the uncertain cases. A device with an internal probe has been developed. It ''lights'' the tube wall with the aid of a transducer of which beam reflects on a mirror. Operating conditions are the same as for Foucault current testing, that is to say the probe moves inside the tube without rotation of the device (bent parts are excluded) [fr
International comparison of electricity generating costs
International Nuclear Information System (INIS)
Jones, P.M.S.; Stevens, G.H.; Wigley, K.
1989-01-01
The paper reviews the principal findings of successive studies of projected comparative generation costs for base-load electricity production conducted by Nuclear Energy Agency working groups, including a current study jointly sponsored by the International Energy Agency. It concludes that over the six years 1983-1989 nuclear generation costs have remained steady or slightly declined in the majority of OECD countries. This represents an excellent result in view of the difficulties that have arisen in many countries during the period. Nuclear power is projected to maintain a significant advantage in most OECD countries on an assessment basis reflecting utility experience and discount rates employed by the majority of participants. However, nuclear's projected advantage has declined due to a significant fall in projected coal prices which have decreased by 50% since 1983. This decline is only slightly offset by increased capital and operating costs for coal-fired plant. If rates of return sought by utilities were higher or if coal prices prove lower than utilities project then the economic balance between nuclear and coal-fired power would be further reduced and could in some instances be reversed. To improve on its competitiveness nuclear power will have to continue to control capital costs through replication and reduced construction schedules and to improve plant availability to maximise output
Overview of toroidal momentum transport
International Nuclear Information System (INIS)
Peeters, A.G.; Hornsby, W.A.; Angioni, C.; Hein, T.; Kluy, N.; Strintzi, D.; Tardini, G.; Bortolon, A.; Camenen, Y.; Casson, F.J.; Snodin, A.P.; Szepesi, G.; Duval, B.; Fiederspiel, L.; Idomura, Y.; Mantica, P.; Parra, F.I.; Tala, T.; De Vries, P.; Weiland, J.
2011-01-01
Toroidal momentum transport mechanisms are reviewed and put in a broader perspective. The generation of a finite momentum flux is closely related to the breaking of symmetry (parity) along the field. The symmetry argument allows for the systematic identification of possible transport mechanisms. Those that appear to lowest order in the normalized Larmor radius (the diagonal part, Coriolis pinch, E x B shearing, particle flux, and up-down asymmetric equilibria) are reasonably well understood. At higher order, expected to be of importance in the plasma edge, the theory is still under development.
Energy Technology Data Exchange (ETDEWEB)
Gerald, Rex E. II; Sanchez, Jairo; Rathke, Jerome W.
2004-08-10
A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.
Toroidal nuclear fusion device
International Nuclear Information System (INIS)
Ito, Yutaka; Kasahara, Tatsuo; Takizawa, Teruhiro.
1975-01-01
Object: To design a device so as to be formed into a large-size and to arrange ports, through which neutral particles enter, in inclined fashion. Structure: Toroidal coils are wound about vacuum vessels which are divided into plural number. In the outer periphery of the vacuum vessels, ports are disposed inclined in the peripheral direction of the vacuum vessels and communicated with the vacuum vessels, and wall surfaces opposed to the ports of the toroidal coils adjacent at least the inclined sides of the ports are inclined substantially simularly to the port wall surfaces. (Kamimura, M.)
International Nuclear Information System (INIS)
Scheffel, J.
1982-04-01
Ideal MHD-equilibria for the toroidal EXTRAP configuration have been computed with an equilibrium code. The free-boundary prob- lem is solved by using the condition that the current density is proportional to r on a flux surface. It is found that the toroidal Z-pinch, initially induced in the central zero-field region of a transverse octupole field, drifts radially outwards producing an inverse -D shaped cross-section. The plasma current of this high- beta equilibrium may be increased if the plasma is pushed back by altering the external confining magnetic field as demonstrated. (Author)
Kinetic extensions of magnetohydrodynamic models for axisymmetric toroidal plasmas
International Nuclear Information System (INIS)
Cheng, C.Z.
1989-04-01
A nonvariational kinetic-MHD stability code (NOVA-K) has been developed to integrate a set of non-Hermitian integro-differential eigenmode equations due to energetic particles for axisymmetric toroidal plasmas in a general flux coordinate system with an arbitrary Jacobian. The NOVA-K code employs the Galerkin method involving Fourier expansions in the generalized poloidal angle θ and generalized toroidal angle /zeta/ directions, and cubic-B spline finite elements in the radial /Psi/ direction. Extensive comparisons with the existing variational ideal MHD codes show that the ideal MHD version of the NOVA-K code converges faster and gives more accurate results. The NOVA-K code is employed to study the effects of energetic particles on MHD-type modes: the stabilization of ideal MHD internal kink modes and the excitation of ''fishbone'' internal kink modes; and the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are also presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n = 1 internal kink mode in the hot particle beta space exists even in the absence of the core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to have negligible effects on the stability of the n = 1 internal kink mode, but the circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 60 refs., 24 figs., 1 tab
Toroidal drift magnetic pumping
International Nuclear Information System (INIS)
Canobbio, E.
1977-01-01
A set of azimuthal coils which carry properly dephased rf-currents in the KHz frequency range can be used to heat toroidal plasmas by perpendicular Landau damping of subsonic Alfven waves. The heating mechanism and the rf-field structure are discussed in some detail
Toroidal 12 cavity klystron : a novel approach
International Nuclear Information System (INIS)
Hazarika, A.B.R.
2013-01-01
A toroidal 12 cavity klystron is designed to provide with high energy power with the high frequency microwave RF- plasma generated from it. The cavities are positioned in clock hour positions. The theoretical modeling and designing is done to study the novel approach. (author)
Femtometer toroidal structures in nuclei
International Nuclear Information System (INIS)
Forest, J.L.; Pandharipande, V.R.; Pieper, S.C.; Wiringa, R.B.; Schiavilla, R.; Arriaga, A.
1996-01-01
The two-nucleon density distributions in states with isospin T=0, spin S=1, and projection M S =0 and ±1 are studied in 2 H, 3,4 He, 6,7 Li, and 16 O. The equidensity surfaces for M S =0 distributions are found to be toroidal in shape, while those of M S =±1 have dumbbell shapes at large density. The dumbbell shapes are generated by rotating tori. The toroidal shapes indicate that the tensor correlations have near maximal strength at r 3 He, 4 He, and 6 Li. The toroidal distribution has a maximum-density diameter of ∼1 fm and a half-maximum density thickness of ∼0.9 fm. Many realistic models of nuclear forces predict these values, which are supported by the observed electromagnetic form factors of the deuteron, and also predicted by classical Skyrme effective Lagrangians, related to QCD in the limit of infinite colors. Due to the rather small size of this structure, it could have a revealing relation to certain aspects of QCD. Experiments to probe this structure and its effects in nuclei are suggested. Pair distribution functions in other T,S channels are also discussed; those in T,S=1,1 have anisotropies expected from one-pion-exchange interactions. The tensor correlations in T,S=0,1 states are found to deplete the number of T,S=1,0 pairs in nuclei and cause a reduction in nuclear binding energies via many-body effects. copyright 1996 The American Physical Society
International Nuclear Information System (INIS)
Ivanov, K.G.; Kharshiladze, A.F.; Eroshenko, E.G.; Styazhkin, V.A.
1988-01-01
Magnetic field experimental profiles, obtained during Vega-I and Vega-2 space vehicles passing through interplanetary cloud on the 16.02.1986, are compared with approximate theoretical profiles, taken from different hypotheses about such clouds structure. Maximum correlation of the theory and experiment is obtained with cloud presentation as flattened compact force-free toroid, which equatorial plane is approximately parallel to great circle plane, passing through flare on the 14.02.86 parallel to magnetic axis nearest to bipolar group flare
Structural design of the superconducting toroidal field coils for ITER
International Nuclear Information System (INIS)
Wong, F.M.G.; Sborchia, C.; Thome, R.J.; Malkov, A.; Titus, P.H.
1995-01-01
Structural design issues and features of the superconducting toroidal field (TF) coils for the International Thermonuclear Experimental Reactor (ITER) will be discussed. Selected analyses of the structural and mechanical behavior of the ITER TF coils will also be presented. (orig.)
International examples of steam generator replacement
International Nuclear Information System (INIS)
Wiechmann, K.
1993-01-01
Since 1979-1980 a total of twelve nuclear power plants world-wide have had their steam generators replaced. The replacement of the Combustion steam generators in the Millstone-2 plant in the United States was completed very recently. Steam generator replacement activities are going on at present in four plants. In North Anna, the steam generators have been under replacement since January 1990. In Japan, preparations have been started for Genkai-1. Since January 1992, the two projects in Beznau-1, Switzerland, and Doel-3, Belgium, have bee planned and executed in parallel. Why steam generator replacement? There are a number of defect mechanisms which give rise to the need for early steam generator replacement. One of the main reasons is the use of Inconel-600 as material for the heating tubes. Steam generator heating tubes made of Inconel-600 have been known to exhibit their first defects due to stress corrosion cracking after less than one year of operation. (orig.) [de
Formation of a compact torus using a toroidal plasma gun
International Nuclear Information System (INIS)
Levine, M.A.; Pincosy, P.A.
1981-01-01
Myers, Levine and Pincosy earlier reported results using a toroidal plasma gun. The device differs from the usual coaxial plasma gun in the use of a strong toroidal bias current for enhanced efficiency, a pair of disk-like accelerating electrodes for reduced viscosity and a fast pulsed toroidal gas valve for more effective use of the injected gas sample. In addition, a technique is used for generating a toroidal current in the plasma ring. The combination offers an opportunity to deliver a plasma with a large amount of energy and to vary the density and relative toroidal and poloidal magnetic field intensities over a range of values. It is the purpose of this paper to report further experimental results, to project the gun's applications to the formation of a compact torus, and to propose a simple modification of the present apparatus as a test
International Geomagnetic Reference Field: the 12th generation
DEFF Research Database (Denmark)
Thébault, Erwan; Finlay, Chris; Beggan, Ciarán D.
2015-01-01
The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch ...
International Nuclear Information System (INIS)
Takizawa, Teruhiro; Shizuoka, Yoshihide.
1982-01-01
Purpose: To reduce the shielding capacity of a current breaker for a current transformer coil and to facilitate the manufacture and the assembly of the current transformer coil. Constitution: A first current transformer coil is provided between a vacuum container for enclosing a plasma and a toroidal magnetic field coil, and a secon current transformer coil is provided outside the toroidal magnetic field coil. The rise of the plasma current is performed by the variation in the current of the coil of the first transformer having high electromagnetic coupling with the plasma current, and the variation in the magnetic flux necessary for maintaining the plasma is performed by the variation in the current of the second transformer coil. In this manner, the current shielding capacity of the first transformer coil can be reduced to decrease the number of coil turns, thereby facilitating the manufacture and assembly. (Seki, T.)
Tokamak with liquid metal toroidal field coil
International Nuclear Information System (INIS)
Ohkawa, T.; Schaffer, M.J.
1981-01-01
Tokamak apparatus includes a pressure vessel for defining a reservoir and confining liquid therein. A toroidal liner disposed within the pressure vessel defines a toroidal space within the liner. Liquid metal fills the reservoir outside said liner. Electric current is passed through the liquid metal over a conductive path linking the toroidal space to produce a toroidal magnetic field within the toroidal space about the major axis thereof. Toroidal plasma is developed within the toroidal space about the major axis thereof
A steady-state axisymmetric toroidal system
International Nuclear Information System (INIS)
Hirano, K.
1984-01-01
Conditions for achieving a steady state in an axisymmetric toroidal system are studied with emphasis on a very-high-beta field-reversed configuration. The analysis is carried out for the electromotive force produced by the Ohkawa current that is induced by neutral-beam injection. It turns out that, since the perpendicular component of the current j-vectorsub(perpendicular) to the magnetic field can be generated automatically by the diamagnetic effect, only the parallel component j-vectorsub(parallel) must be driven by the electromotive force. The drive of j-vectorsub(parallel) generates shear in the field line so that the pure toroidal field on the magnetic axis is rotated towards the plasma boundary and matched to the external field lines. This matching condition determines the necessary amount of injection beam current and power. It is demonstrated that a very-high-beta field-reversed configuration requires only a small amount of current-driving beam power because almost all the toroidal current except that close to the magnetic axis is carried by the diamagnetic current due to high beta. A low-beta tokamak, on the other hand, needs very high current-driving power since most of the toroidal current is composed of j-vectorsub(parallel) which must be driven by the beam. (author)
Toroidal vortices in resistive magnetohydrodynamic equilibria
International Nuclear Information System (INIS)
Montgomery, D.; Bates, J.W.; Li, S.
1997-01-01
When a time-independent electric current flows toroidally in a uniform ring of electrically conducting fluid, a Lorentz force results, jxB, where j is the local electric current density, and B is the magnetic field it generates. Because of purely geometric effects, the curl of jxB is nonvanishing, and so jxB cannot be balanced by the gradient of any scalar pressure. Taking the curl of the fluid close-quote s equation of motion shows that the net effect of the jxB force is to generate toroidal vorticity. Allowed steady states necessarily contain toroidal vortices, with flows in the poloidal directions. The flow pattern is a characteristic open-quotes double smoke ringclose quotes configuration. The effect seems quite general, although it is analytically simple only in special limits. One limit described here is that of high viscosity (low Reynolds number), with stress-free wall boundary conditions on the velocity field, although it is apparent that similar mechanical motions will result for no-slip boundaries and higher Reynolds numbers. A rather ubiquitous connection between current-carrying toroids and vortex rings seems to be implied, one that disappears in the open-quotes straight cylinderclose quotes limit. copyright 1997 American Institute of Physics
Internal current generation in respiration chambers
Saborowski, R.; Buchholz, F.
1998-06-01
A technical device generating a constant and directed current within a sealed respiration chamber is described. It does not involve any external pumps or tubing. This system is easy to handle, and improved the maintenance of rheotactic pelagic species like the Northern krill ( Meganyctiphanes norvegica, Crustacea) or small fishes ( Gasterosteus aculeatus) under experimental conditions.
Superconducting endcap toroid design report
Energy Technology Data Exchange (ETDEWEB)
Walters, C.R.; Baynham, D.E.; Holtom, E.; Coombs, R.C.
1992-10-01
The Atlas Experiment proposed for the LHC machine will use toroidal magnet systems to achieve high muon momentum resolutions. One of the options under consideration is an air cored superconducting toroidal magnet system consisting of a long barrel toroid with small and cap toroids inserted in it to provide high resolution at high pseudorapidity. The design of the barrel toroid has been studied over the past two years and the design outline is given in a Saclay Report. More recently consideration has been given to an end cap toroid system which is based on air cored superconducting coils. This report presents the basic engineering design of such a system, the proposals for fabrication, assembly and installation, and an outline cost estimate for one end cap is presented in Appendix 1.
Supporting device for Toroidal coils
International Nuclear Information System (INIS)
Araki, Takao.
1985-01-01
Purpose: To reduce the response of a toroidal coil supporting device upon earthquakes and improve the earthquake proofness in a tokamak type thermonuclear device. Constitution: Structural materials having large longitudinal modulus and enduring great stresses, for example, stainless steels are used as the toroidal coil supporting legs and heat insulating structural materials are embedded in a nuclear reactor base mats below the supporting legs. Furthermore, heat insulating concretes are spiked around the heat insulating structural materials to prevent the intrusion of heat to the toroidal coils. The toroidal coils are kept at cryogenic state and superconductive state for the conductors. In this way, the period of proper vibrations of the toroidal coils and the toroidal coil supporting structures can be shortened thereby decreasing the seismic response. Furthermore, since the strength of the supporting legs is increased, the earthquake proofness of the coils can be improved. (Kamimura, M.)
The international cooperation for 4. generation systems
International Nuclear Information System (INIS)
Bouchard, J.
2007-01-01
This series of slides begins with a likely scenario for the demand of nuclear power in 2050: 3.2 Gtep compared to the 0.7 Gtep of today. The demand could be even bigger if more constraints were appearing on the use of fossil energies. Today's industrial offer of nuclear reactors is based on second and third generation design of reactors but sustainable development implies to close the fuel cycle to spare uranium resource and to minimize the volume of high-level radioactive wastes produced so a new generation of reactors is required. 6 concepts have been selected for the fourth generation of reactors. 1) VHTR (Very High Temperature Reactors) for the production of hydrogen. The countries interested in VHTR are: EURATOM countries, France, the Usa, Japan, Switzerland and South-Korea. 2) SFR (Sodium cooled Fast Reactors), the countries interested in SFR are: EURATOM countries, France, Japan, the Usa and South-Korea. 3) LFR (Lead or Bismuth/Lead cooled Fast Reactors), the LFR steering committee is composed of Switzerland, Japan, the Usa and South-Korea. 4) GFR (Gas cooled Fast Reactors), the countries interested in GFR are EURATOM countries, France, Japan and Switzerland. 5) SCWR (Super-Critical Water cooled Reactors), the countries interested in this concept are Canada, EURATOM countries and Japan. 6) MSR (Molten Salt Reactors), the MSR steering committee is composed of France, EURATOM countries and the Usa. Other countries like Argentina, Brazil and United-Kingdom have shown interest in the VHTR concept but have lacked willingness till now to take part into the program. (A.C.)
Toroidal rotation studies in KSTAR
Lee, S. G.; Lee, H. H.; Yoo, J. W.; Kim, Y. S.; Ko, W. H.; Terzolo, L.; Bitter, M.; Hill, K.; KSTAR Team
2014-10-01
Investigation of the toroidal rotation is one of the most important topics for the magnetically confined fusion plasma researches since it is essential for the stabilization of resistive wall modes and its shear plays an important role to improve plasma confinement by suppressing turbulent transport. The most advantage of KSTAR tokamak for toroidal rotation studies is that it equips two main diagnostics including the high-resolution X-ray imaging crystal spectrometer (XICS) and charge exchange spectroscopy (CES). Simultaneous core toroidal rotation and ion temperature measurements of different impurity species from the XICS and CES have shown in reasonable agreement with various plasma discharges in KSTAR. It has been observed that the toroidal rotation in KSTAR is faster than that of other tokamak devices with similar machine size and momentum input. This may due to an intrinsically low toroidal field ripple and error field of the KSTAR device. A strong braking of the toroidal rotation by the n = 1 non-resonant magnetic perturbations (NRMPs) also indicates these low toroidal field ripple and error field. Recently, it has been found that n = 2 NRMPs can also damp the toroidal rotation in KSTAR. The detail toroidal rotation studies will be presented. Work supported by the Korea Ministry of Science, ICT and Future Planning under the KSTAR project.
Neoclassical transport in toroidal systems
International Nuclear Information System (INIS)
Wobig, H.
1992-01-01
The neoclassical theory of general toroidal equilibria is reformulated. The toroidal equilibrium of tokamaks and stellarators are described in Hamada coordinates. The relevant geometrical parameters are identified and it is shown how the reduction of Pfirsch-Schluter currents affects neoclassical transport and bootstrap effects. General flux-friction relations between thermodynamic forces and fluxes are derived. In drift-kinetic approximation the neoclassical transport coefficients are Onsager symmetric. Since a toroidal loop voltage is included, the theory is valid for all toroidal systems. (Author)
Toroidal simulation magnet tests
International Nuclear Information System (INIS)
Walstrom, P.L.; Domm, T.C.
1975-01-01
A number of different schemes for testing superconducting coils in a simulated tokamak environment are analyzed for their merits relative to a set of test criteria. Two of the concepts are examined in more detail: the so-called cluster test scheme, which employs two large background field coils, one on either side of the test coil, and the compact torus, a low-aspect ratio toroidal array of a small number of coils in which all of the coils are essentially test coils. Simulation of the pulsed fields of the tokamak is discussed briefly
Poloidal variations in toroidal fusion reactor wall power loadings
International Nuclear Information System (INIS)
Carroll, M.C.; Miley, G.H.
1985-01-01
A geometric formulation is developed by the authors for determining poloidal variations in bremmstrahlung, cyclotron radiation, and neutron wall power loadings in toroidal fusion devices. Assuming toroidal symmetry and utilizing a numerical model which partitions the plasma into small cells, it was generally found that power loadings are highest on the outer surface of the torus, although variations are not as large as some have predicted. Results are presented for various plasma power generation configurations, plasma volume fractions, and toroidal aspect ratios, and include plasma and wall blockage effects
Long-wavelength microinstabilities in toroidal plasmas
International Nuclear Information System (INIS)
Tang, W.M.; Rewoldt, G.
1993-01-01
Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Res. (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 29] L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities
International Nuclear Information System (INIS)
Johnson, R.L.
1985-01-01
The Advanced Toroidal Facility (ATF) is a new magnetic confinement plasma device under construction at the Oak Ridge National Laboratory (ORNL) that will lead to improvements in toroidal magnetic fusion reactors. The ATF is a type of stellerator, known as a ''torsatron'' which theoretically has the capability to operate at greater than or equal to8% beta in steady state. The ATF plasma has a major radius of 2.1 m, an average minor radius of 0.3 m, and a field of 2 T for a 2 s duration or 1 T steady state. The ATF device consists of a helical field (HF) coil set, a set of poloidal field (PF) coils, an exterior shell structure to support the coils, and a thin, helically contoured vacuum vessel inside the coils. The ATF replaces the Impurities Studies Experiment (ISX-B) tokamak at ORNL and will use the ISX-B auxiliary systems including 4 MW of electron cyclotron heating. The ATF is scheduled to start operation in late 1986. An overview of the ATF device is presented, including details of the construction process envisioned. 9 refs., 7 figs., 3 tabs
Advanced Toroidal Facility (ATF)
International Nuclear Information System (INIS)
Thompson, P.B.
1985-01-01
The Advanced Toroidal Facility (ATF) is a new magnetic plasma confinement device, under construction at Oak Ridge National Laboratory (ORNL), which will lead to improvements in toroidal magnetic fusion reactors. ATF is a type of stellarator known as a torsatron which theoretically has the capability at greater than or equal to8% beta in steady state. The ATF plasma has a major radius of 2.1 m, an average minor radius of 0.3 m, and a field of 2 T for a 5-s duration or 1 T steady state. The ATF device consists of a helical field (HF) coil set, a set of poloidal field (PF) coils, an exterior shell structure to support the coils, and a thin helically contoured vacuum vessel inside the coils. The ATF replaces the ISX-B tokamak at ORNL and will use the ISX-B auxiliary systems including 4 MW of neutral injection heating and 0.2 MW of electron cyclotron heating. ATF device is scheduled to start operation in the fall of 1986. An overview of the ATF device is presented including details of the construction process envisioned
Reynolds stress of localized toroidal modes
International Nuclear Information System (INIS)
Zhang, Y.Z.; Mahajan, S.M.
1995-02-01
An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant
Reynolds stress of localized toroidal modes
International Nuclear Information System (INIS)
Zhang, Y.Z.; Mahajan, S.M.
1995-01-01
An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant. (author). 15 refs
Quantum mechanics of toroidal anions
International Nuclear Information System (INIS)
Afanas'ev, G.N.
1990-01-01
We consider a toroidal solenoid with an electric charge attached to it. It turns out that statistical properties of the wave function describing interacting toroidal anions depend on both their relative position and orientation. The influence of the particular gauge choice on the exchange properties of the wave function is studied. 30 refs.; 6 figs
TORFA - toroidal reactor for fusion applications
International Nuclear Information System (INIS)
Jassby, D.L.
1980-09-01
The near-term goal of the US controlled fusion program should be the development, for practical applications, of an intense, quasi-steady, reliable 14-MeV neutron source with an electrical utilization efficiency at least 10 times larger than the value characterizing beam/solid-target neutron generators. This report outlines a method for implementing that goal, based on tokamak fusion reactors featuring resistive toroidal-field coils designed for ease of demountability
Energy Technology Data Exchange (ETDEWEB)
Han, Song; Yang, Helin [College of Physical Science and Technology, Central China Normal University, Wuhan (China); Cong, Lonqing; Singh, Ranjan [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Gao, Fei [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore)
2016-05-15
Toroidal multipoles have recently been explored in various scientific communities, ranging from atomic and molecular physics, electrodynamics, and solid-state physics to biology. Here we experimentally and numerically demonstrate a three-dimensional toroidal metamaterial where two different toroidal dipoles along orthogonal directions have been observed. The chosen toroidal metamaterial also simultaneously supports Fano resonance and the classical analog of electromagnetically induced transparency (EIT) phenomena in the transmission spectra that originate from the electric-toroidal dipole and electric-magnetic dipole destructive interference. The intriguing properties of the toroidal resonances may open up avenues for applications in toroidal moments generator, sensing and slow-light devices. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
International Geomagnetic Reference Field: the 12th generation
Thébault , Erwan; Finlay , Christopher ,; Beggan , Ciarán ,; Alken , Patrick; Aubert , Julien ,; Barrois , Olivier; Bertrand , François; Bondar , Tatiana; Boness , Axel; Brocco , Laura; Canet , Elisabeth ,; Chambodut , Aude; Chulliat , Arnaud ,; Coïsson , Pierdavide ,; Civet , François
2015-01-01
International audience; The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, p...
The optimization of longitudinal convective fins with internal heat generation
International Nuclear Information System (INIS)
Razelos, P.
1979-01-01
The solution of the optimization problem for longitudinal convective fins of constant thickness, triangular or parabolic profile, and uniform internal heat generation, is presented. The cases considered are those of a given heat generation density, total heat generation and heat generation per unit width of the fin, when either the heat dissipation or the width of the fin is prescribed. The results are set forth in a nondimensional form, which are presented graphically. The effect of the fin's thermal conductivity upon the optimum dimensions is discussed, and limiting values for the heat generation and the heat dissipation, which may be imposed on the fin for a feasible optimization, are also obtained. (Auth.)
Device for supporting a toroidal coil in a toroidal type nuclear fusion device
International Nuclear Information System (INIS)
Kitazawa, Hakaru; Sato, Hiroshi.
1975-01-01
Object: To easily manufacture a center block having a strength sufficient to withstand an electromagnetic force exerted on the center of toroidal of a toroidal coil and to increase its reliability. Structure: In a device for supporting toroidal coils wherein the electromagnetic force exerted on the center of toroidal of a plurality of toroidal coils arranged in toroidal fashion, the contact surface between the toroidal coil and the center block is arranged parallel to the center axis of toroidal so as to receive the electromagnetic force exerted on the center of toroidal of the toroidal coil as the component of force in a radial direction. (Taniai, N.)
Turbulent and neoclassical toroidal momentum transport in tokamak plasmas
International Nuclear Information System (INIS)
Abiteboul, J.
2012-10-01
The goal of magnetic confinement devices such as tokamaks is to produce energy from nuclear fusion reactions in plasmas at low densities and high temperatures. Experimentally, toroidal flows have been found to significantly improve the energy confinement, and therefore the performance of the machine. As extrinsic momentum sources will be limited in future fusion devices such as ITER, an understanding of the physics of toroidal momentum transport and the generation of intrinsic toroidal rotation in tokamaks would be an important step in order to predict the rotation profile in experiments. Among the mechanisms expected to contribute to the generation of toroidal rotation is the transport of momentum by electrostatic turbulence, which governs heat transport in tokamaks. Due to the low collisionality of the plasma, kinetic modeling is mandatory for the study of tokamak turbulence. In principle, this implies the modeling of a six-dimensional distribution function representing the density of particles in position and velocity phase-space, which can be reduced to five dimensions when considering only frequencies below the particle cyclotron frequency. This approximation, relevant for the study of turbulence in tokamaks, leads to the so-called gyrokinetic model and brings the computational cost of the model within the presently available numerical resources. In this work, we study the transport of toroidal momentum in tokamaks in the framework of the gyrokinetic model. First, we show that this reduced model is indeed capable of accurately modeling momentum transport by deriving a local conservation equation of toroidal momentum, and verifying it numerically with the gyrokinetic code GYSELA. Secondly, we show how electrostatic turbulence can break the axisymmetry and generate toroidal rotation, while a strong link between turbulent heat and momentum transport is identified, as both exhibit the same large-scale avalanche-like events. The dynamics of turbulent transport are
Form coefficient of helical toroidal solenoids
International Nuclear Information System (INIS)
Amelin, V.Z.; Kunchenko, V.B.
1982-01-01
For toroidal solenoids with continuous spiral coil, winded according to the laws of equiinclined and simple cylindrical spirals with homogeneous, linearly increasing to the coil periphery and ''Bitter'' distribution of current density, the analytical expressions for the dependence between capacity consumed and generated magnetic field, expressions for coefficients of form similar to Fabry coefficient for cylindrical solenoids are obtained and dependence of the form coefficient and relative volume of solenoid conductor on the number of revolutions of screw line per one circumvention over the large torus radius is also investigated. Analytical expressions of form coefficients and graphical material permit to select the optimum geometry as to capacity consumed both for spiral (including ''force-free'') and conventional toroidal solenoids of magnetic systems in thermonulear installations
Process gas generator feeding internal combustion piston engines
Energy Technology Data Exchange (ETDEWEB)
Iwantscheff, G; Kostka, H; Henkel, H J
1978-10-26
The invention relates to a process gas generator feeding gaseous fuel to internal combustion piston engines. The cylinder linings of the internal combustion engine are enclosed by the catalytic reaction chamber of the process gas generator which contains perforated sintered nozzle bricks as carriers of the catalysts needed for the conversion. The reaction chamber is surrounded by the exhaust gas chamber around which a tube coil is ound which feeds the fuel charge to the reaction chamber after evaporation and mixing with exhaust gas and air. The fuel which may be used for this purpose, e.g., is low-octane gasoline or diesel fuel. In the reaction chamber the fuel is catalytically converted at temperatures above 200/sup 0/C, e.g., into low-molecular paraffins, carbon monoxide and hydrogen. Operation of the internal combustion engine with a process gas generator greatly reduces the pollutant content of the exhaust gases.
Experimental studies of plasma confinement in toroidal systems
International Nuclear Information System (INIS)
Bodin, H.A.B.; Keen, B.E.
1977-01-01
In this article the closed-line magnetic field approach to the plasma isolation and confinement problem in toroidal systems is reviewed. The theoretical aspects of closed-line magnetic field systems, indicating that topologically such systems are toroidal, are surveyed under the headings; topology of closed-line systems, equilibrium in different configurations and classification of toroidal devices, MHD stability, non-ideal effects in MHD stability, microscopic stability, and plasma energy loss. A section covering the experimental results of plasma confinement in toroidal geometry considers Stellerators, Tokamaks, toroidal pinch -the reversed-field pinch, screw pinches and high-β Tokamaks, Levitrons and multipoles (internal-ring devices), and miscellaneous toroidal containment devices. Recent achievements and the present position are discussed with reference to the status of Tokamak research, low-β stellerator research and high-β research. It is concluded from the continuing progress made in this research that the criteria for the magnetic containment of plasmas can be met. Further, it is concluded that the construction of a successful and economic fusion reactor is within the scope of advancing science and technology. 250 references. (U.K.)
Experimental studies of plasma confinement in toroidal systems
Energy Technology Data Exchange (ETDEWEB)
Bodin, H A.B.; Keen, B E [UKAEA, Abingdon. Culham Lab.
1977-12-01
In this article the closed-line magnetic field approach to the plasma isolation and confinement problem in toroidal systems is reviewed. The theoretical aspects of closed-line magnetic field systems, indicating that topologically such systems are toroidal, are surveyed under the headings; topology of closed-line systems, equilibrium in different configurations and classification of toroidal devices, MHD stability, non-ideal effects in MHD stability, microscopic stability, and plasma energy loss. A section covering the experimental results of plasma confinement in toroidal geometry considers Stellerators, Tokamaks, toroidal pinch -the reversed-field pinch, screw pinches and high-..beta.. Tokamaks, Levitrons and multipoles (internal-ring devices), and miscellaneous toroidal containment devices. Recent achievements and the present position are discussed with reference to the status of Tokamak research, low-..beta.. stellerator research and high-..beta.. research. It is concluded from the continuing progress made in this research that the criteria for the magnetic containment of plasmas can be met. Further, it is concluded that the construction of a successful and economic fusion reactor is within the scope of advancing science and technology. 250 references.
Investigations of toroidal wave numbers of the kink instabilities in a toroidal pinch plasma
International Nuclear Information System (INIS)
Hamajima, Takataro; Irisawa, Juichi; Tsukada, Tokuaki; Sugito, Osamu; Maruyama, Hideaki
1979-01-01
The axial toroidal wave numbers of the kink instability of toroidal pinch plasma were measured and investigated with a specially designed coil, and the results were compared with the MHD theory. The schematic figure and the particulars of the experimental apparatus are briefly illustrated in the first part. The method of generating theta-Z pinch plasma, the wave form of the magnetic flux density in Z-direction and the plasma current are also explained. The 360 deg stereoscopic framing photographs were taken with an image converter camera at the intervals of 0.5 μs after the initiation of the main electric discharge in Z-circuit. From these photographs, the growth of the kink instability was observed. The measured magnetic field distribution at t = 2 μs is presented. In the second part, the radial displacement of plasma and toroidal wave number were measured from the above framing photographs. Then the spectra of plasma displacement were analyzed by the Fourier analysis. The measured results of toroidal wave number was analyzed by both the skin current model and the diffuse current model. Many new results obtained from the present study were mainly derived from the observation of the framing photographs, and they are summarized in the final part of this paper. (Aoki, K.)
Current drive by asymmetrical heating in a toroidal plasma
International Nuclear Information System (INIS)
Gahl, J.M.
1986-01-01
This report describes the first experimental observation of current generation by asymmetrical heating of ions. A unidirectional fast Alfven wave launched by a slow-wave antenna inside the Texas Tech Tokamak, asymmetrically heated the ions. Measurements of the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column confirmed the current generation indirectly. Current generation, obtained in a one-species, hydrogen plasma, is a phenomenon which had not been predicted previously. Calculations of the dispersion relation for the fast Alfven wave near the fundamental cyclotron resonance in a one-species, hydrogen plasma, using warm plasma theory, support the experimental results
Grinding Inside A Toroidal Cavity
Mayer, Walter; Adams, James F.; Burley, Richard K.
1987-01-01
Weld lines ground smooth within about 0.001 in. Grinding tool for smoothing longitudinal weld lines inside toroidal cavity includes curved tunnel jig to guide grinding "mouse" along weld line. Curvature of tunnel jig matched to shape of toroid so grinding ball in mouse follows circular arc of correct radius as mouse is pushed along tunnel. Tool enables precise control of grindout shape, yet easy to use.
Equivelar toroids with few flag-orbits
Collins, José; Montero, Antonio
2018-01-01
An $(n+1)$-toroid is a quotient of a tessellation of the $n$-dimensional Euclidean space with a lattice group. Toroids are generalizations of maps in the torus on higher dimensions and also provide examples of abstract polytopes. Equivelar toroids are those that are induced by regular tessellations. In this paper we present a classification of equivelar $(n+1)$-toroids with at most $n$ flag-orbits; in particular, we discuss a classification of $2$-orbit toroids of arbitrary dimension.
International Nuclear Information System (INIS)
G Onishchenko, O; A Pokhotelov, O; Horton, W; Stenflo, L
2014-01-01
The equations describing axi-symmetric nonlinear internal gravity waves in an unstable atmosphere are derived. A hydrodynamic model of a dust devil generation mechanism in such an atmosphere is investigated. It is shown that in an unstably stratified atmosphere the convective plumes with poloidal motion can grow exponentially. Furthermore, it is demonstrated that these convective plumes in an atmosphere with weak large scale toroidal motion are unstable with respect to three-dimensional dust devil generation. (papers)
Efficiency of wave-driven rigid body rotation toroidal confinement
Rax, J. M.; Gueroult, R.; Fisch, N. J.
2017-03-01
The compensation of vertical drifts in toroidal magnetic fields through a wave-driven poloidal rotation is compared with compensation through the wave driven toroidal current generation to support the classical magnetic rotational transform. The advantages and drawbacks associated with the sustainment of a radial electric field are compared with those associated with the sustainment of a poloidal magnetic field both in terms of energy content and power dissipation. The energy content of a radial electric field is found to be smaller than the energy content of a poloidal magnetic field for a similar set of orbits. The wave driven radial electric field generation efficiency is similarly shown, at least in the limit of large aspect ratio, to be larger than the efficiency of wave-driven toroidal current generation.
3D Printing the ATLAS' barrel toroid
Goncalves, Tiago Barreiro
2016-01-01
The present report summarizes my work as part of the Summer Student Programme 2016 in the CERN IR-ECO-TSP department (International Relations – Education, Communication & Outreach – Teacher and Student Programmes). Particularly, I worked closely with the S’Cool LAB team on a science education project. This project included the 3D designing, 3D printing, and assembling of a model of the ATLAS’ barrel toroid. A detailed description of the project' development is presented and a short manual on how to use 3D printing software and hardware is attached.
Bifurcation theory for toroidal MHD instabilities
International Nuclear Information System (INIS)
Maschke, E.K.; Morros Tosas, J.; Urquijo, G.
1992-01-01
Using a general representation of magneto-hydrodynamics in terms of stream functions and potentials, proposed earlier, a set of reduced MHD equations for the case of toroidal geometry had been derived by an appropriate ordering with respect to the inverse aspect ratio. When all dissipative terms are neglected in this reduced system, it has the same linear stability limits as the full ideal MHD equations, to the order considered. When including resistivity, thermal conductivity and viscosity, we can apply bifurcation theory to investigate nonlinear stationary solution branches related to various instabilities. In particular, we show that a stationary solution of the internal kink type can be found
Tearing modes in toroidal geometry
International Nuclear Information System (INIS)
Connor, J.W.; Cowley, S.C.; Hastie, R.J.; Hender, T.C.; Hood, A.; Martin, T.J.
1988-01-01
The separation of the cylindrical tearing mode stability problem into a resistive resonant layer calculation and an external marginal ideal magnetohydrodynamic (MHD) calculation (Δ' calculation) is generalized to axisymmetric toroidal geometry. The general structure of this separation is analyzed and the marginal ideal MHD information (the toroidal generalization of Δ') required to discuss stability is isolated. This can then, in principle, be combined with relevant resonant layer calculations to determine tearing mode growth rates in realistic situations. Two examples are given: the first is an analytic treatment of toroidally coupled (m = 1, n = 1) and (m = 2, n = 1) tearing modes in a large aspect ratio torus; the second, a numerical treatment of the toroidal coupling of three tearing modes through finite pressure effects in a large aspect ratio torus. In addition, the use of a coupling integral approach for determining the stability of coupled tearing modes is discussed. Finally, the possibility of using initial value resistive MHD codes in realistic toroidal geometry to determine the necessary information from the ideal MHD marginal solution is discussed
Outlook of nuclear power generation and international situation
Energy Technology Data Exchange (ETDEWEB)
Ekulund, S [International Atomic Energy Agency, Vienna (Austria)
1978-01-01
Nuclear power generation is advancing at rapid rate over the world, without any major accident. For the base load of electric power, when choice is made between nuclear energy and petroleum, Nuclear energy has larger economic advantages over petroleum as compared with the days before the oil crisis. The costs of its fuel and fuel cycle technology are reasonable. However, nuclear power generation currently has a number of problems. What causes this uncertainty is not technological, but political, i.e. governmental policy changes, and this is based on the apprehension about nuclear proliferation. What is necessary is to strengthen the existing international framework of nuclear nonproliferation. In this respect, IAEA through comprehensive safeguards will make contributions largely to reduction of the political uncertainty. It is important that the new initiatives toward international nuclear cooperation should eliminate the current trends of restraint and denial.
High current density toroidal pinch discharges with weak toroidal fields
International Nuclear Information System (INIS)
Brunsell, P.; Brzozowski, J.; Drake, J.R.; Hellblom, G.; Kaellne, E.; Mazur, S.; Nordlund, P.
1990-01-01
Toroidal discharges in the ultralow q regime (ULQ) have been studied in the rebuilt Extrap TI device. ULQ discharges are sustained for pulse lengths exceeding 1 ms, which corresponds to more than 10 resistiv shell times. Values for the safety factor at the vacuum vessel wall are between rational values: 1/(n+1) -2 . The magnetic fluctuation level increases during the transition between rational values of q(a). For very low values of q(a), the loop voltage increases and the toroidal field development in the discharge exhibits the characteristic behaviour of the setting-up phase of a field reversed pinch. (author) 1 ref., 2 figs., 1 tab
Study of entropy generation in a slab with non-uniform internal heat generation
Directory of Open Access Journals (Sweden)
El Haj Assad Mamdouh
2013-01-01
Full Text Available Analysis of entropy generation in a rectangular slab with a nonuniform internal heat generation is presented. Dimensionless local and total entropy generation during steady state heat conduction through the slab are obtained. Two different boundary conditions have been considered in the analysis, the first with asymmetric convection and the second with constant slab surface temperature. Temperature distribution within the slab is obtained analytically. The study investigates the effect of some relevant dimensionless heat transfer parameters on entropy generation. The results show that there exists a minimum local entropy generation but there does not exist a minimum total entropy generation for certain combinations of the heat transfer parameters. The results of calculations are presented graphically.
General Atomic's superconducting toroidal field coil concept
International Nuclear Information System (INIS)
Alcorn, J.; Purcell, J.
1978-01-01
General Atomic's concept for a superconducting toroidal field coil is presented. The concept is generic for large tokamak devices, while a specific design is indicated for a 3.8 meter (major radius) ignition/burn machine. The concept utilizes bath cooled NbTi conductor to generate a peak field of 10 tesla at 4.2 K. The design is simple and straightforward, requires a minimum of developmental effort, and draws extensively upon the perspective of past experience in the design and construction of large superconducting magnets for high energy physics. Thus, the primary emphasis is upon economy, reliability, and expeditious construction scheduling. (author)
The International Geomagnetic Reference Field: the twelfth generation
Thebault, Erwan; Finlay, Christopher; The IGRF Working Group
2015-04-01
The IGRF is an internationally-agreed reference model of the Earth's magnetic field produced under the auspices of the International Association of Geomagnetism and Aeronomy. The IGRF-12 is the latest update of this well-known model which is used each year by many thousands of users for both industrial and scientific purposes. In October 2014, ten institutions worldwide have made contributions to the IGRF. These models were evaluated and the twelfth generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014. In this presentation, we will report on the IGRF activities, briefly describe the candidate models, summarize the evaluation of models performed by different independent teams, show how the IGRF-12 models were calculated and finally discuss some of the main magnetic features of this new model.
International project GT-MHR - New generation of nuclear reactors
International Nuclear Information System (INIS)
Vasyaev, A.; Kodochigov, N.; Kuzavkov, N.; Kuznetsov, L.
2001-01-01
Gas turbine-modular helium reactor (GT-MHR) is the reactor of new generation, which satisfies the requirements of the progressing large-scale nuclear power engineering. The activities in GT-MHR Project started in 1995. In 1997 the Conceptual Design was developed under four-side Agreement (MINATOM, General Atomics, FRAMATOME, Fuji Electric); it has passed through the internal and international reviews, has been approved and recommended for further development as one of new trends in creation of new generation plants. Starting from 1999, the activities in the development of the Preliminary Design of the plant were deployed under the Agreement between the Government of the United States of America and the Government of the Russian Federation on Scientific and Technical Cooperation in the Management of Plutonium That Has Been Withdrawn From Nuclear Military Programs dated July 24, 1998. The activities are established under the Contract between MINATOM and OKBM Russia, and under the General Agreement between Department of Energy (DOE), USA and OKBM. The GT-MHR Project is included into 'Development Strategy of Russian Nuclear Power in the first Half of the XXI-st Century' providing for 'the participation in an international project on the development and construction of GT-MHR nuclear power plant till year 2010 and 'operation of GT-MHR prototype unit and creation of fuel fabrication facility (within framework of International Project) till year 2030'. (author)
Inside-out: comparing internally generated and externally generated basic emotions.
Salas, Christian E; Radovic, Darinka; Turnbull, Oliver H
2012-06-01
A considerable number of mood induction (MI) procedures have been developed to elicit emotion in normal and clinical populations. Although external procedures (e.g., film clips, pictures) are widely used, a number of experiments elicit emotion by using self-generated procedures (e.g., recalling an emotional personal episode). However, no study has directly compared the effectiveness of two types of internal versus external MI across multiple discrete emotions. In the present experiment, 40 undergraduate students watched film clips (external procedure) and recalled personal events (internal procedure) inducing 4 basic emotions (fear, anger, joy, sadness) and later completed a self-report questionnaire. Remarkably, both internal and external procedures elicited target emotions selectively, compared with nontarget emotions. When contrasting the intensity of target emotions, both techniques showed no significant differences, with the exception of Joy, which was more intensely elicited by the internal procedure. Importantly, when considering the overall level of intensity, it was always greater in the internal procedure, for each stimulus. A more detailed investigation of the data suggest that recalling personal events (a type of internal procedure) generates more negative and mixed blends of emotions, which might account for the overall higher intensity of the internal mood induction.
Toroidal Trivelpiece-Gould modes
International Nuclear Information System (INIS)
Stoessel, F.P.
1979-01-01
Electron plasma waves are treated in quasi-electrostatic approximation in a toroidal cavity of rectangular cross-section in an infinitely strong azimuthal magnetic field. The differential equation for the electrostatic potential, derived from fluid equations, can be separated using cylindrical coordinates. The eigenvalue problem for the radial dependence is solved numerically by a shooting method. Eigenvalues are given for different aspect ratios. Comparison with appropriate modes of the straight geometry shows that the toroidal frequencies generally lie some percent above those for the straight case. Plots of the eigenfunctions demonstrate clearly the influence of toroidicity. The deviation from symmetry (which should appear for straight geometry) depends not only on the aspect ratio but also strongly on the mode numbers. (author)
MHD equilibrium with toroidal rotation
International Nuclear Information System (INIS)
Li, J.
1987-03-01
The present work attempts to formulate the equilibrium of axisymmetric plasma with purely toroidal flow within ideal MHD theory. In general, the inertial term Rho(v.Del)v caused by plasma flow is so complicated that the equilibrium equation is completely different from the Grad-Shafranov equation. However, in the case of purely toroidal flow the equilibrium equation can be simplified so that it resembles the Grad-Shafranov equation. Generally one arbitrary two-variable functions and two arbitrary single variable functions, instead of only four single-variable functions, are allowed in the new equilibrium equations. Also, the boundary conditions of the rotating (with purely toroidal fluid flow, static - without any fluid flow) equilibrium are the same as those of the static equilibrium. So numerically one can calculate the rotating equilibrium as a static equilibrium. (author)
Generation 4 International Forum (GIF). 2015 Annual Report
International Nuclear Information System (INIS)
2016-01-01
This ninth edition of the Generation IV International Forum (GIF) Annual Report highlights the main achievements of the Forum in 2015. On 26 February 2015, the Framework Agreement for International Collaboration on Research and Development of Generation IV Nuclear Energy Systems was extended for another ten years, thereby paving the way for continued collaboration among participating countries. GIF organised the 3. Symposium in Makuhari Messe, Japan in May 2015 to present progress made in the development of the six generation IV systems: the gas-cooled fast reactor, the sodium-cooled fast reactor, the supercritical-water-cooled reactor, the very-high-temperature reactor, the lead-cooled fast reactor and the molten salt reactor. The report gives a detailed description of progress made in the 11 existing project arrangements. It also describes the development of safety design criteria and guidelines for the sodium-cooled fast reactor, in addition to the outcome of GIF engagement with regulators on safety approaches for generation IV systems. (authors)
Work-Related Attitudes of Czech Generation Z: International Comparison
Directory of Open Access Journals (Sweden)
Jaroslava Kubátová,
2016-12-01
Full Text Available The goal of this article is to present work-related attitudes of a sample of Czech Generation Z and their comparison to the results of an international research study. Currently, there are three important trends influencing the labor market: (1 the origin and development of a ubiquitous working environment, (2 the thriving of coworking centers, and (3 Generation Z's entering the labor market. Instead of traditional jobs, the bearers of human capital tend to choose independent work in an online environment, and often work in coworking centers. Using self-determination theory, we substantiate why they thrive better this way. Based on the results of an international research project focused on work attitudes among Generation Z and the results of a replication study we carried out in the Czech Republic, we attest that members of Generation Z may prefer independent virtual work in coworking centers, too. The total amount of available human capital, the lack of which is pointed out by companies, may grow thanks to new ways of working. Companies, which can use human capital of independent workers, gain a competitive advantage.
Prandtl number of toroidal plasmas
International Nuclear Information System (INIS)
Itoh, K.; Itoh, S.; Fukuyama, A.; Yagi, M.; Azumi, M.
1993-06-01
Theory of the L-mode confinement in toroidal plasmas is developed. The Prandtl number, the ratio between the ion viscosity and the thermal conductivity is obtained for the anomalous transport process which is caused by the self-sustained turbulence in the toroidal plasma. It is found that the Prandtl number is of order unity both for the ballooning mode turbulence in tokamaks and for the interchange mode turbulence in helical system. The influence on the anomalous transport and fluctuation level is evaluated. Hartmann number and magnetic Prandtl number are also discussed. (author)
Couston, Louis-Alexandre; Lecoanet, Daniel; Favier, Benjamin; Le Bars, Michael
2017-11-01
We investigate via direct numerical simulations the spontaneous generation and reversals of mean zonal flows in a stably-stratified fluid layer lying above a turbulent convective fluid. Contrary to the leading idealized theories of mean flow generation by self-interacting internal waves, the emergence of a mean flow in a convectively-generated internal gravity wave field is not always possible because nonlinear interactions of waves of different frequencies can disrupt the mean flow generation mechanism. Strong mean flows thus emerge when the divergence of the Reynolds stress resulting from the nonlinear interactions of internal waves produces a strong enough anti-diffusive acceleration for the mean flow, which, as we will demonstrate, is the case when the Prandtl number is sufficiently low, or when the energy input into the internal wavefield by the convection and density stratification are sufficiently large. Implications for mean zonal flow production as observed in the equatorial stratospheres of the Earth, Saturn and Jupiter, and possibly occurring in other geophysical systems such as planetary and stellar interiors will be briefly discussed. Funding provided by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program through Grant Agreement No. 681835-FLUDYCO-ERC-2015-CoG.
Toroidal current asymmetry in tokamak disruptions
Strauss, H. R.
2014-10-01
It was discovered on JET that disruptions were accompanied by toroidal asymmetry of the toroidal plasma current I ϕ. It was found that the toroidal current asymmetry was proportional to the vertical current moment asymmetry with positive sign for an upward vertical displacement event (VDE) and negative sign for a downward VDE. It was observed that greater displacement leads to greater measured I ϕ asymmetry. Here, it is shown that this is essentially a kinematic effect produced by a VDE interacting with three dimensional MHD perturbations. The relation of toroidal current asymmetry and vertical current moment is calculated analytically and is verified by numerical simulations. It is shown analytically that the toroidal variation of the toroidal plasma current is accompanied by an equal and opposite variation of the toroidal current flowing in a thin wall surrounding the plasma. These currents are connected by 3D halo current, which is π/2 radians out of phase with the n = 1 toroidal current variations.
The complex and unique ATLAS Toroid family
2002-01-01
Big parts for the toroid magnets that will be used in the ATLAS experiment have been continuously arriving at CERN since March. These structures will create the largest superconducting toroid magnet ever.
X-ray imaging with toroidal mirror
International Nuclear Information System (INIS)
Aoki, Sadao; Sakayanagi, Yoshimi
1978-01-01
X-ray imaging is made with a single toroidal mirror or two successive toroidal mirrors. Geometrical images at the Gaussian image plane are described by the ray trace. Application of a single toroidal mirror to small-angle scattering is presented. (author)
Theory for neoclassical toroidal plasma viscosity in tokamaks
International Nuclear Information System (INIS)
Shaing, K C; Chu, M S; Hsu, C T; Sabbagh, S A; Seol, Jae Chun; Sun, Y
2012-01-01
Error fields and magnetohydrodynamic modes break toroidal symmetry in tokamaks. The broken symmetry enhances the toroidal plasma viscosity, which results in a steady-state toroidal plasma flow. A theory for neoclassical toroidal plasma viscosity in the low-collisionality regimes is developed. It extends stellarator transport theory to include multiple modes and to allow for |m − nq| ∼ 1. Here, m is the poloidal mode number, n is the toroidal mode number and q is the safety factor. The bounce averaged drift kinetic equation is solved in several asymptotic limits to obtain transport fluxes. These fluxes depend non-linearly on the radial electric field except for those in the 1/ν regime. Here, ν is the collision frequency. The theory is refined to include the effects of the superbanana plateau resonance at the phase space boundary and the finite ∇B drift on the collisional boundary layer fluxes. Analytical expressions that connect all asymptotic limits are constructed and are in good agreement with the numerical results. The flux–force relations that relate transport fluxes to forces are used to illustrate the roles of transport fluxes in the momentum equation. It is shown that the ambipolar state is reached when the momentum equation is relaxed. It is also shown that the origin of the momentum for plasma flow generated without momentum sources is the local unbalance of particles' momenta and is diamagnetic in nature regardless of the details of the theory. (paper)
Onsager relaxation of toroidal plasmas
International Nuclear Information System (INIS)
Samain, A.; Nguyen, F.
1997-01-01
The slow relaxation of isolated toroidal plasmas towards their thermodynamical equilibrium is studied in an Onsager framework based on the entropy metric. The basic tool is a variational principle, equivalent to the kinetic equation, involving the profiles of density, temperature, electric potential, electric current. New minimization procedures are proposed to obtain entropy and entropy production rate functionals. (author)
Particle simulations in toroidal geometry
International Nuclear Information System (INIS)
Aydemir, A.Y.
1992-09-01
A computational tool to be used in kinetic simulations of toroidal plasmas is being developed. The initial goal of the project is to develop an electrostatic gyrokinetic model for studying transport and stability problems in tokamaks. In this brief report, preliminary results from the early stages of this effort are presented
Lowering the first ATLAS toroid
Maximilien Brice
2004-01-01
The ATLAS detector on the LHC at CERN will consist of eight toroid magnets, the first of which was lowered into the cavern in these images on 26 October 2004. The coils are supported on platforms where they will be attached to form a giant torus. The platforms will hold about 300 tonnes of ATLAS' muon chambers and will envelop the inner detectors.
Hybrid winding concept for toroids
DEFF Research Database (Denmark)
Schneider, Henrik; Andersen, Thomas; Knott, Arnold
2013-01-01
and placement machinery. This opens up the possibility for both an automated manufacturing process and an automated production process of toroidal magnetics such as power inductors, filtering inductors, air core inductors, transformers etc. Both the proposed hybrid and the common wire wound winding...
Collapse analysis of toroidal shell
International Nuclear Information System (INIS)
Pomares, R.J.
1990-01-01
This paper describes a study performed to determine the collapse characteristics of a toroidal shell using finite element method (FEM) analysis. The study also included free drop testing of a quarter scale prototype to verify the analytical results. The full sized toroidal shell has a 24-inch toroidal diameter with a 24-inch tubal diameter. The shell material is type 304 strainless steel. The toroidal shell is part of the GE Model 2000 transportation packaging, and acts as an energy absorbing device. The analyses performed were on a full sized and quarter scaled models. The finite element program used in all analyses was the LIBRA code. The analytical procedure used both the elasto-plastic and large displacement options within the code. The loading applied in the analyses corresponded to an impact of an infinite rigid plane oriented normal to the drop direction vector. The application of the loading continued incrementally until the work performed by the deforming structure equalled the kinetic energy developed in the free fall. The comparison of analysis and test results showed a good correlation
Internal oxidation as a mechanism for steam generator tube degradation
Energy Technology Data Exchange (ETDEWEB)
Gendron, T.S. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Scott, P.M. [Framatome, Paris (France); Bruemmer, S.M. [Pacific Northwest National Laboratory, Richland, WA (United States); Thomas, L.E. [Washington State Univ., School of Mechanical and Materials Engineering, Pullman, WA (United States)
1999-12-01
Internal oxidation has been proposed as a plausible mechanism for intergranular stress-corrosion cracking (IGSCC) of alloy 600 steam generator tubing. This theory can reconcile the main thermodynamic and kinetic characteristics of the observed cracking in hydrogenated primary water. Although secondary-side IG attack or IGSCC is commonly attributed to the presence of strong, caustic or acidic solutions, more recent evidence suggests that this degradation takes place in a near neutral environment, possibly dry polluted steam. As a result, internal oxidation is also a feasible mechanism for secondary side degradation. The present paper reviews experimental work conducted in an attempt to determine the validity of this mechanism. The consequences for the expected behaviour of alloys 690 and 800 replacement materials are also described. (author)
Internal oxidation as a mechanism for steam generator tube degradation
Energy Technology Data Exchange (ETDEWEB)
Gendron, T.S. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Scott, P.M. [Framatome, Paris (France); Bruemmer, S.M. [Pacific Northwest National Lab., Richland, Washington (United States); Thomas, L.E. [Washington State Univ., School of Mechanical and Materials Engineering, Pullman, WA (United States)
1998-07-01
Internal oxidation has been proposed as a plausible mechanism for intergranular stress corrosion cracking (IGSCC) of alloy 600 steam generator tubing. This theory can reconcile the main thermodynamic and kinetic characteristics of the observed cracking in hydrogenated primary water. Although secondary side IG attack or IGSCC is commonly attributed to the presence of strong caustic or acidic solutions, more recent evidence suggests that this degradation takes place in a near-neutral environment, possibly dry polluted steam. As a result, internal oxidation is also a feasible mechanism for secondary side degradation. The present paper reviews experimental work carried out in an attempt to determine the validity of this mechanism. The consequences for the expected behaviour of alloys 690 and 800 replacement materials are also described. (author)
Review on Korea Participation of Generation IV International Forum (GIF)
Energy Technology Data Exchange (ETDEWEB)
Lee, Jewhan; Jeong, Ji-Young; Hahn, Dohee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2015-05-15
Generation IV International Forum (GIF) originates from US proposal of an initiative in 2000. The vision was to leapfrog LWR technology and collaborate with international partners to share R and D on advanced nuclear systems. Nine countries and EU joined the initiative and Gen IV concept was defined via technology goals and legal framework. Two years study with more than 100 experts worldwide has evaluated nearly 100 reactor designs and down selected six most promising concepts. In 2005, the first signatures on Framework Agreement were collected and the first research projects were defined in 2006. Korea is one of the founding members of GIF and actively participating in various areas. In 2013, TD was assigned to Korean expert and Korea is endeavoring to enhance the benefit of participation since this turning point. In this paper, pros and cons of engaging with GIF were briefly introduced and items to maximize the benefit were suggested.
Review on Korea Participation of Generation IV International Forum (GIF)
International Nuclear Information System (INIS)
Lee, Jewhan; Jeong, Ji-Young; Hahn, Dohee
2015-01-01
Generation IV International Forum (GIF) originates from US proposal of an initiative in 2000. The vision was to leapfrog LWR technology and collaborate with international partners to share R and D on advanced nuclear systems. Nine countries and EU joined the initiative and Gen IV concept was defined via technology goals and legal framework. Two years study with more than 100 experts worldwide has evaluated nearly 100 reactor designs and down selected six most promising concepts. In 2005, the first signatures on Framework Agreement were collected and the first research projects were defined in 2006. Korea is one of the founding members of GIF and actively participating in various areas. In 2013, TD was assigned to Korean expert and Korea is endeavoring to enhance the benefit of participation since this turning point. In this paper, pros and cons of engaging with GIF were briefly introduced and items to maximize the benefit were suggested
Internal oxidation as a mechanism for steam generator tube degradation
International Nuclear Information System (INIS)
Gendron, T.S.; Scott, P.M.; Bruemmer, S.M.; Thomas, L.E.
1998-01-01
Internal oxidation has been proposed as a plausible mechanism for intergranular stress corrosion cracking (IGSCC) of alloy 600 steam generator tubing. This theory can reconcile the main thermodynamic and kinetic characteristics of the observed cracking in hydrogenated primary water. Although secondary side IG attack or IGSCC is commonly attributed to the presence of strong caustic or acidic solutions, more recent evidence suggests that this degradation takes place in a near-neutral environment, possibly dry polluted steam. As a result, internal oxidation is also a feasible mechanism for secondary side degradation. The present paper reviews experimental work carried out in an attempt to determine the validity of this mechanism. The consequences for the expected behaviour of alloys 690 and 800 replacement materials are also described. (author)
Microwave produced plasma in a Toroidal Device
Singh, A. K.; Edwards, W. F.; Held, E. D.
2010-11-01
A currentless toroidal plasma device exhibits a large range of interesting basic plasma physics phenomena. Such a device is not in equilibrium in a strict magneto hydrodynamic sense. There are many sources of free energy in the form of gradients in plasma density, temperature, the background magnetic field and the curvature of the magnetic field. These free energy sources excite waves and instabilities which have been the focus of studies in several devices in last two decades. A full understanding of these simple plasmas is far from complete. At Utah State University we have recently designed and installed a microwave plasma generation system on a small tokamak borrowed from the University of Saskatchewan, Saskatoon, Canada. Microwaves are generated at 2.45 GHz in a pulsed dc mode using a magnetron from a commercial kitchen microwave oven. The device is equipped with horizontal and vertical magnetic fields and a transformer to impose a toroidal electric field for current drive. Plasmas can be obtained over a wide range of pressure with and without magnetic fields. We present some preliminary measurements of plasma density and potential profiles. Measurements of plasma temperature at different operating conditions are also presented.
Design features of HTMR-Hybrid Toroidal Magnet Tokamak Reactor
International Nuclear Information System (INIS)
Rosatelli, F.; Avanzini, P.G.; Brunelli, B.; Derchi, D.; Magnasco, M.; Grattarola, M.; Peluffo, M.; Raia, G.; Zampaglione, V.
1985-01-01
The HTMR (Hybrid Toroidal Magnet Tokamak Reactor) conceptual design is aimed to demonstrate the feasibility of a Tokamak reactor which could fulfill the scientific and technological objectives expected from next generation devices (e.g. INTOR-NET) with size and costs as small as possible. An hybrid toroidal field magnet, made up by copper and superconducting coils, seems to be a promising solution, allowing a considerable flexibility in machine performances, so as to gain useful margins in front of the uncertainties in confinement time scaling laws and beta and plasma density limits. In this paper the authors describe the optimization procedure for the hybrid magnet configuration, the main design features of HTMR and the preliminary mechanical calculations of the superconducting toroidal coils
Design features of HTMR-hybrid toroidal magnet tokamak reactor
International Nuclear Information System (INIS)
Rosatelli, F.; Avanzini, P.G.; Derchi, D.; Magnasco, M.; Grattarola, M.; Peluffo, M.; Raia, G.; Brunelli, B.; Zampaglione, V.
1984-01-01
The HTMR (Hybrid Toroidal Magnet Tokamak Reactor) conceptual design is aimed to demonstrate the feasibility of a Tokamak reactor which could fulfil the scientific and technological objectives expected from next generation devices with size and costs as small as possible. A hybrid toroidal field magnet, made up by copper and superconducting coils, seems to be a promising solution, allowing a considerable flexibility in machine performances, so as to gain useful margins in front of the uncertainties in confinement time scaling laws and beta and plasma density limits. The optimization procedure for the hybrid magnet, configuration, the main design features of HTMR and the preliminary mechanical calculations of the superconducting toroidal coils are described. (author)
Toroidal plasma enhanced CVD of diamond films
International Nuclear Information System (INIS)
Zvanya, John; Cullen, Christopher; Morris, Thomas; Krchnavek, Robert R.; Holber, William; Basnett, Andrew; Basnett, Robert; Hettinger, Jeffrey
2014-01-01
An inductively coupled toroidal plasma source is used as an alternative to microwave plasmas for chemical vapor deposition of diamond films. The source, operating at a frequency of 400 kHz, synthesizes diamond films from a mixture of argon, methane, and hydrogen. The toroidal design has been adapted to create a highly efficient environment for diamond film deposition: high gas temperature and a short distance from the sample to the plasma core. Using a toroidal plasma geometry operating in the medium frequency band allows for efficient (≈90%) coupling of AC line power to the plasma and a scalable path to high-power and large-area operation. In test runs, the source generates a high flux of atomic hydrogen over a large area, which is favorable for diamond film growth. Using a deposition temperature of 900–1050 °C and a source to sample distance of 0.1–2.0 cm, diamond films are deposited onto silicon substrates. The results showed that the deposition rate of the diamond films could be controlled using the sample temperature and source to sample spacing. The results also show the films exhibit good-quality polycrystalline diamond as verified by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. The scanning electron microscopy and x-ray diffraction results show that the samples exhibit diamond (111) and diamond (022) crystallites. The Raman results show that the sp 3 peak has a narrow spectral width (FWHM 12 ± 0.5 cm −1 ) and that negligible amounts of the sp 2 band are present, indicating good-quality diamond films
Impact of Physical Abuse on Internalizing Behavior Across Generations.
Esteves, Kyle; Gray, Sarah A O; Theall, Katherine P; Drury, Stacy S
2017-10-01
This study investigated the multigenerational impact of mothers' own exposure to physical maltreatment on internalizing symptoms in her child after accounting for her parenting practices, depression, and the child's own exposure to stressful life events. Children ( n = 101, ages 5-16), predominantly African American, were recruited into this cross sectional study using ethnographic mapping and targeted sampling for high-risk neighborhoods. Mothers reported retrospectively on their own exposure to physical maltreatment in childhood, their parenting practices, as well as current depressive symptoms. Maternal report of her child's exposure to stressful life events and child behavior was also collected. Maternal childhood exposure to physical maltreatment was significantly associated with her child's internalizing symptoms ( p = .004); this effect remained after accounting for child sex, maternal depressive symptoms, harsh parenting practices, and the child's own exposure to stressful life events. Formal tests of mediation through these pathways were non-significant. Findings suggest mothers' experience of childhood maltreatment contributes uniquely to children's internalizing symptoms, potentially through previously uncharacterized pathways. Examination of additional behavioral, psychosocial and biological pathways may help better describe the multi-generational effects of child maltreatment.
Integrating Renewable Generation into Grid Operations: Four International Experiences
Energy Technology Data Exchange (ETDEWEB)
Weimar, Mark R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mylrea, Michael E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Levin, Todd [Argonne National Lab. (ANL), Argonne, IL (United States); Botterud, Audun [Argonne National Lab. (ANL), Argonne, IL (United States); O' Shaughnessy, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bird, Lori [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2016-04-22
International experiences with power sector restructuring and the resultant impacts on bulk power grid operations and planning may provide insight into policy questions for the evolving United States power grid as resource mixes are changing in response to fuel prices, an aging generation fleet and to meet climate goals. Australia, Germany, Japan and the UK were selected to represent a range in the level and attributes of electricity industry liberalization in order to draw comparisons across a variety of regions in the United States such as California, ERCOT, the Southwest Power Pool and the Southeast Reliability Region. The study draws conclusions through a literature review of the four case study countries with regards to the changing resource mix and the electricity industry sector structure and their impact on grid operations and planning. This paper derives lessons learned and synthesizes implications for the United States based on answers to the above questions and the challenges faced by the four selected countries. Each country was examined to determine the challenges to their bulk power sector based on their changing resource mix, market structure, policies driving the changing resource mix, and policies driving restructuring. Each countries’ approach to solving those changes was examined, as well as how each country’s market structure either exacerbated or mitigated the approaches to solving the challenges to their bulk power grid operations and planning. All countries’ policies encourage renewable energy generation. One significant finding included the low- to zero-marginal cost of intermittent renewables and its potential negative impact on long-term resource adequacy. No dominant solution has emerged although a capacity market was introduced in the UK and is being contemplated in Japan. Germany has proposed the Energy Market 2.0 to encourage flexible generation investment. The grid operator in Australia proposed several approaches to maintaining
Classification of symmetric toroidal orbifolds
Energy Technology Data Exchange (ETDEWEB)
Fischer, Maximilian; Ratz, Michael; Torrado, Jesus [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-09-15
We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N{>=}1 supersymmetry in 4D for the heterotic string. Our strategy is based on a classification of crystallographic space groups in six dimensions. We find in total 520 inequivalent toroidal orbifolds, 162 of them with Abelian point groups such as Z{sub 3}, Z{sub 4}, Z{sub 6}-I etc. and 358 with non-Abelian point groups such as S{sub 3}, D{sub 4}, A{sub 4} etc. We also briefly explore the properties of some orbifolds with Abelian point groups and N=1, i.e. specify the Hodge numbers and comment on the possible mechanisms (local or non-local) of gauge symmetry breaking.
Hollow nanotubular toroidal polymer microrings.
Lee, Jiyeong; Baek, Kangkyun; Kim, Myungjin; Yun, Gyeongwon; Ko, Young Ho; Lee, Nam-Suk; Hwang, Ilha; Kim, Jeehong; Natarajan, Ramalingam; Park, Chan Gyung; Sung, Wokyung; Kim, Kimoon
2014-02-01
Despite the remarkable progress made in the self-assembly of nano- and microscale architectures with well-defined sizes and shapes, a self-organization-based synthesis of hollow toroids has, so far, proved to be elusive. Here, we report the synthesis of polymer microrings made from rectangular, flat and rigid-core monomers with anisotropically predisposed alkene groups, which are crosslinked with each other by dithiol linkers using thiol-ene photopolymerization. The resulting hollow toroidal structures are shape-persistent and mechanically robust in solution. In addition, their size can be tuned by controlling the initial monomer concentrations, an observation that is supported by a theoretical analysis. These hollow microrings can encapsulate guest molecules in the intratoroidal nanospace, and their peripheries can act as templates for circular arrays of metal nanoparticles.
Compact toroids with Alfvenic flows
International Nuclear Information System (INIS)
Wang Zhehui; Tang, X.Z.
2004-01-01
The Chandrasekhar equilibria form a class of stationary ideal magnetohydrodynamics equilibria stabilized by magnetic-field-aligned Alfvenic flows. Analytic solutions of the Chandrasekhar equilibria are explicitly constructed for both field-reversed configurations and spheromaks. Favorable confinement property of nested closed flux surfaces and the ideal magnetohydrodynamic stability of the compact toroids are of interest for both magnetic trapping of high energy electrons in astrophysics and confinement of high temperature plasmas in laboratory
Locked magnetic island chains in toroidally flow damped tokamak plasmas
International Nuclear Information System (INIS)
Fitzpatrick, R; Waelbroeck, F L
2010-01-01
The physics of a locked magnetic island chain maintained in the pedestal of an H-mode tokamak plasma by a static, externally generated, multi-harmonic, helical magnetic perturbation is investigated. The non-resonant harmonics of the external perturbation are assumed to give rise to significant toroidal flow damping in the pedestal, in addition to the naturally occurring poloidal flow damping. Furthermore, the flow damping is assumed to be sufficiently strong to relax the pedestal ion toroidal and poloidal fluid velocities to fixed values determined by neoclassical theory. The resulting neoclassical ion flow causes a helical phase-shift to develop between the locked island chain and the resonant harmonic of the external perturbation. Furthermore, when this phase-shift exceeds a critical value, the chain unlocks from the resonant harmonic and starts to rotate, after which it decays away and is replaced by a helical current sheet. The neoclassical flow also generates an ion polarization current in the vicinity of the island chain which either increases or decreases the chain's radial width, depending on the direction of the flow. If the polarization effect is stabilizing, and exceeds a critical amplitude, then the helical island equilibrium becomes unstable, and the chain again decays away. The critical amplitude of the resonant harmonic of the external perturbation at which the island chain either unlocks or becomes unstable is calculated as a function of the pedestal ion pressure, the neoclassical poloidal and toroidal ion velocities and the poloidal and toroidal flow damping rates.
International Nuclear Information System (INIS)
Vlases, G.C.
1989-01-01
During the period from August 1988 to August 1989, the CSS project has made progress in three areas: The Coaxial Slow Source Upgrade CSSU version of the device was operated until January of 1989. In the Fall of 1988 Langmuir probes were installed to measure the end losses, the Thomson scattering system was made more sensitive, and a more detailed scan with internal magnetic probes was performed. Since then, the CSSU-centered work has concentrated on refining the analysis and interpretation of data. The CSS device was rebuilt as CSSP in the period Jan--June 1989, and began operation on July 3, 1989. Simultaneously, a new data acquisition and processing system based on a Vax 3200 workstation and MDS and IDL software was developed. The COAX 2 code was significant improved by the treatment of hydrogen ionization, including the radiative loss terms, and the inclusion of a more consistent transport and impurity radiation package. The improved code was used both to interpret the results of the CSSU experiments, and to predict performance for the CSSP and CSS2 devices. Details of these three areas of progress are given in the following sections
Design considerations for ITER toroidal field coils
International Nuclear Information System (INIS)
Kalsi, S.S.; Lousteau, D.C.; Miller, J.R.
1987-01-01
The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Europe, Japan, the Union of Soviet Socialist Republics (U.S.S.R.), and the United States. This paper describes a magnetic and mechanical design methodology for toroidal field (TF) coils that employs Nb 3 Sn superconductor technology. Coil winding is sized by using conductor concepts developed for the U.S. TIBER concept. Manifold concepts are presented for the complete cooling system. Also included are concepts for the coil structural arrangement. The effects of in-plane and out-of-plane loads are included in the design considerations for the windings and case. Concepts are presented for reacting these loads with a minimum amount of additional structural material. Concepts discussed in this paper could be considered for the ITER TF coils
ATF [Advanced Toroidal Facility] data management
International Nuclear Information System (INIS)
Kannan, K.L.; Baylor, L.R.
1988-01-01
Data management for the Advanced Toroidal Facility (ATF), a stellarator located at Oak Ridge National Laboratory (ORNL), is provided by DMG, a locally developed, VAX-based software system. DMG is a data storage and retrieval software system that provides the user interface to ATF raw and analyzed data. Data are described in terms of data models and data types and are organized as signals into files, which are internally documented. The system was designed with user accessibility, software maintainability, and extensibility as primary goals. Extensibility features include compatibility with ATF as it moves from pulsed to steady-state operation and capability for use of the DMG system with experiments other than ATF. DMG is implemented as a run-time library of routines available as a shareable image. General-purpose and specialized data acquisition and analysis applications have been developed using the DMG system. This paper describes the DMG system and the interfaces to it. 4 refs., 2 figs
Spatial Variations of Poloidal and Toroidal Mode Field Line Resonances Observed by MMS
Le, G.; Chi, P. J.; Strangeway, R. J.; Russell, C. T.; Slavin, J. A.; Anderson, B. J.; Kepko, L.; Nakamura, R.; Plaschke, F.; Torbert, R. B.
2017-12-01
Field line resonances (FLRs) are magnetosphere's responses to solar wind forcing and internal instabilities generated by solar wind-magnetospheric interactions. They are standing waves along the Earth's magnetic field lines oscillating in either poloidal or toroidal modes. The two types of waves have their unique frequency characteristics. The eigenfrequency of FLRs is determined by the length of the field line and the plasma density, and thus gradually changes with L. For toroidal mode oscillations with magnetic field perturbations in the azimuthal direction, ideal MHD predicts that each field line oscillates independently with its own eigenfrequency. For poloidal mode waves with field lines oscillating radially, their frequency cannot change with L easily as L shells need to oscillate in sync to avoid efficient damping due to phase mixing. Observations, mainly during quiet times, indeed show that poloidal mode waves often exhibit nearly constant frequency across L shells. Our recent observations, on the other hand, reveal a clear L-dependent frequency trend for a long lasting storm-time poloidal wave event, indicating the wave can maintain its power with changing frequencies for an extended period [Le et al., 2017]. The spatial variation of the frequency shows discrete spatial structures. The frequency remains constant within each discrete structure that spans about 1 REalong L, and changes discretely. We present a follow-up study to investigate spatial variations of wave frequencies using the Wigner-Ville distribution. We examine both poloidal and toroidal waves under different geomagnetic conditions using multipoint observations from MMS, and compare their frequency and occurrence characteristics for insights into their generation mechanisms. Reference: Le, G., et al. (2017), Global observations of magnetospheric high-m poloidal waves during the 22 June 2015 magnetic storm, Geophys. Res. Lett., 44, 3456-3464, doi:10.1002/2017GL073048.
Feedback control of resistive wall modes in toroidal devices
International Nuclear Information System (INIS)
Liu, Y.Q.
2002-01-01
Active feedback of resistive wall modes is investigated using cylindrical theory and toroidal calculations. For tokamaks, good performance is obtained by using active coils with one set of coils in the poloidal direction and sensors detecting the poloidal field inside the first wall, located at the outboard mid-plane. With suitable width of the feedback coil such a system can give robust control with respect to variations in plasma current, pressure and rotation. Calculations are shown for ITER-like geometry with a double wall. The voltages and currents in the active coils are well within the design limits for ITER. Calculations for RFP's are presented for a finite number of coils both in the poloidal and toroidal directions. With 4 coils in the poloidal and 24 coils in the toroidal direction, all non-resonant modes can be stabilized both at high and low theta. Several types of sensors, including radial and internal poloidal or toroidal sensors, can stabilize the RWM, but poloidal sensors give the most robust performance. (author)
Heating of toroidal plasmas by neutral injection
International Nuclear Information System (INIS)
Stix, T.H.
1971-08-01
This paper presents a brief review of the physics of ion acceleration, charge exchange and ionization, trajectories for fast ions in toroidal magnetic fields, and fast-ion thermalization. The injection of fast atoms is found to be a highly competitive method both for heating present-day experimental toroidal plasmas and for bringing full-scale toroidal CTR plasmas to low-density ignition. 13 refs., 9 figs
Observation of plasma toroidal-momentum dissipation by neoclassical toroidal viscosity.
Zhu, W; Sabbagh, S A; Bell, R E; Bialek, J M; Bell, M G; LeBlanc, B P; Kaye, S M; Levinton, F M; Menard, J E; Shaing, K C; Sontag, A C; Yuh, H
2006-06-09
Dissipation of plasma toroidal angular momentum is observed in the National Spherical Torus Experiment due to applied nonaxisymmetric magnetic fields and their plasma-induced increase by resonant field amplification and resistive wall mode destabilization. The measured decrease of the plasma toroidal angular momentum profile is compared to calculations of nonresonant drag torque based on the theory of neoclassical toroidal viscosity. Quantitative agreement between experiment and theory is found when the effect of toroidally trapped particles is included.
Internal and ancestral controls of cell-generation times
Kubitschek, H. E.
1969-01-01
Lateral and longitudinal correlations between related cells reveal associations between the generation times of cells for an intermediate period /three generations in bacteral cultures/. Generation times of progeny are influenced by nongenetic factors transmitted from their ancestors.
Modeling internal wave generation by seamounts in oceans
Zhang, L.; Buijsman, M. C.; Comino, E. L.; Swinney, H.
2017-12-01
Recent global bathymetric data at 30 arc-sec resolution has revealed that there are 33,452 seamounts and 138,412 knolls in the oceans. To develop an estimate for the energy converted from tidal flow to internal gravity waves, we have conducted numerical simulations using the Massachusetts Institute of Technology circulation model (MITgcm) to compute the energy conversion by randomly distributed Gaussian-shaped seamounts. We find that for an isolated axisymmetric seamount of height 1100 m and radius 1600 m, which corresponds to the Wessel height-to-radius ratio 0.69, the conversion rate is 100 kW, assuming a tidal speed amplitude 1 cm/s, buoyancy frequency 1e-3 rad/s, and circularly polarized tidal motion, and taking into account the earth's rotation. The 100 kW estimate is about 60% less than the 3-D linear theory prediction because fluid goes around a seamount instead of over it. Our estimate accounts the suppression of energy conversion due to wave interference at the generation site of closely spaced seamounts. We conclude that for randomly distributed Gaussian seamounts of varying widths and separations, separated on average by 18 km as in the oceans, wave interference reduces the energy conversion by seamounts by only about 16%. This result complements previous studies of wave interference for 2-D ridges.
Plasma Discharge in Toroidal System
International Nuclear Information System (INIS)
Usada, Widdi; Suryadi; Purwadi, Agus; Kasiyo
1996-01-01
A toroidal discharge apparatus has been made as an initial research in magnetic confinement system. This system consists of a capacitor, a RF source, an igniter system, a primary coil, a torus, and completed by Rogowski probe as a current detector. In this system, the discharge occurs when the minimum voltage is operated at 5 kV. The experiment result shows that the coupling factor is 0.35, it is proved that there is an equality between estimated and measurement results of the primary inductance i.e 8.5 μH
Pellet injection and toroidal confinement
International Nuclear Information System (INIS)
1989-12-01
The proceedings of a technical committee meeting on pellet injection and toroidal confinement, held in Gut Ising, Federal Republic of Germany, 24-26 October, 1988, are given in this report. Most of the major fusion experiments are using pellet injectors; these were reported at this meeting. Studies of confinement, which is favorably affected, impurity transport, radiative energy losses, and affects on the ion temperature gradient instability were given. Studies of pellet ablation and effects on plasma profiles were presented. Finally, several papers described present and proposed injection guns. Refs, figs and tabs
Analysis of the TFTR toroidal field power supply and its interactions with other loads
International Nuclear Information System (INIS)
Newell, W.E.
1976-01-01
The rectifiers which supply the four major pulsed loads of the Tokamak Fusion Test Reactor (TFTR) share two flywheel generators. Thus there is a possibility of significant interaction between these rectifiers by way of the notched voltage waveforms which they create at the generator terminals. This paper presents an analysis of the build up of current in the toroidal field (TF) coil, which is the largest load. From this analysis, the notched waveform caused by the TF rectifier is derived and its effect on the other rectifiers is investigated. It is concluded that with the present conceptual design parameters, the external effects of the interactions are likely to be small. However, the internal control circuits of the rectifiers must be carefully designed to minimize those effects
Progress on large superconducting toroidal field coils
International Nuclear Information System (INIS)
Haubenreich, P.N.; Luton, J.N.; Thompson, P.B.; Beard, D.S.
1979-01-01
Large superconducting toroidal field coils of competing designs are being produced by six major industrial teams. In the US, teams headed by General Dynamics Convair, General Electric, and Westinghouse are under contract to design and fabricate one coil each to specifications established by the Large Coil Program. A facility for testing 6 coils in a toroidal array at fields to 8 to 12 tesla is under construction at Oak Ridge. Through an international agreement, EURATOM, Japan, and Switzerland will produce one coil each for testing with the US coils. Each test coil will have a 2.5 x 3.5 m D-shape winding bore and is designed to operate at a current of 10 to 18 kA at a peak field of 8T while subjected to pulsed fields of 0.14 T applied in 1.0 s. There are significant differences among the six coil designs: five use NbTi, one Nb 3 Sn; three are cooled by pool boiling helium, three by forced flow; five have welded or bolted stainless steel coil cases, one has aluminum plate structure. All are designed to be cryostable at 8T, with structural margin for extended operation. The three US coil teams are almost or completely finished with detailed design and are now procuring materials and setting up manufacturing equipment. The non-US teams are at various stages of verification testing and design. The GDC and GE coils are scheduled for delivery in the spring of 1981 and the others will be completed a year later. The 11-m diameter vessel at the test facility has been completed and major components of the test stand are being procured. Engineering and procurement to upgrade the helium liquifier-refrigerator system are under way
Thermal mechanical analysis of applications with internal heat generation
Govindarajan, Srisharan Garg
The radioactive tracer Technetium-99m is widely used in medical imaging and is derived from its parent isotope Molybedenum-99 (Mo-99) by radioactive decay. The majority of Molybdenum-99 (Mo-99) produced internationally is extracted from high enriched uranium (HEU) dispersion targets that have been irradiated. To alleviate proliferation risks associated with HEU-based targets, the use of non-HEU sources is being mandated. However, the conversion of HEU to LEU based dispersion targets affects the Mo-99 available for chemical extraction. A possible approach to increase the uranium density, to recover the loss in Mo-99 production-per-target, is to use an LEU metal foil placed within an aluminum cladding to form a composite structure. The target is expected to contain the fission products and to dissipate the generated heat to the reactor coolant. In the event of interfacial separation, an increase in the thermal resistance could lead to an unacceptable rise in the LEU temperature and stresses in the target. The target can be deemed structurally safe as long as the thermally induced stresses are within the yield strength of the cladding and welds. As with the thermal and structural safety of the annular target, the thermally induced deflection of the BORALRTM-based control blades, used by the University of Missouri Research Reactor (MURRRTM ), during reactor operation has been analyzed. The boron, which is the neutron absorber in BORAL, and aluminum mixture (BORAL meat) and the aluminum cladding are bonded together through powder metallurgy to establish an adherent bonded plate. As the BORAL absorbs both neutron particles and gamma rays, there is volumetric heat generation and a corresponding rise in temperature. Since the BORAL meat and aluminum cladding materials have different thermal expansion coefficients, the blade may have a tendency to deform as the blade temperature changes and the materials expand at different rates. In addition to the composite nature of the
BPX toroidal field coil design
International Nuclear Information System (INIS)
Heitzenvoeder, D.J.
1992-01-01
This paper reports on the toroidal field (TF) coil system of the Burning Plasma Experiment (BPX) which consists of (18) beryllium copper magnets arrayed in a wedged configuration with a major radius of 2.6 meters and a field strength capability on axis of 9.0 Tesla. The toroidal array is constructed from six (3)-coil modules to facilitate remote recovery in the event of a magnet failure after nuclear activation precludes hands-on servicing. The magnets are of a modified Bitter plate design with partial cases of type 316-LN stainless steel welded with Inconel 182 weld wire. The coil turn plates are fabricated from CDA C17510 beryllium copper with optimized mechanical, thermal, and electrical characteristics. joints within the turns and between turns are made by welding with C17200 filler wire. Cryogenic cooling is employed to reduce power dissipation and to enhance performance. The magnets are cooled between experimental pulses by pressurized liquid nitrogen flowing through channels in the edges of the coil turns. This arrangement makes possible one full-power pulse per hour. Electrical insulation consists of polyimide-glass sheets bonded in place with vacuum-pressure impregnated epoxy/glass
Generation 4 International Forum. 2009 GIF R and D outlook for generation 4 nuclear energy systems
International Nuclear Information System (INIS)
2009-01-01
This document presents the state, at mid 2009, of research and development of the 6 reactor types that were selected in the framework of the GIF (Generation 4 International Forum): VHTR (Very High Temperature Reactor), SFR (Sodium-cooled Fast Reactor), SCWR (Super-Critical Water Reactor), GFR (Gas-cooled Fast Reactor), LFR (Lead-cooled reactor), and MSR (Molten Salt Reactor). Regarding each type of reactors, the state of advancement is reported for the reactor itself, its specific components and materials, its nuclear fuel, and its fuel cycle. The outlook of development and research work is also given for the next 5 years for the 6 types of reactors. (A.C.)
Generating Bona Fide Mammalian Prions with Internal Deletions.
Munoz-Montesino, Carola; Sizun, Christina; Moudjou, Mohammed; Herzog, Laetitia; Reine, Fabienne; Chapuis, Jérôme; Ciric, Danica; Igel-Egalon, Angelique; Laude, Hubert; Béringue, Vincent; Rezaei, Human; Dron, Michel
2016-08-01
disorders. Other aggregation-prone proteins appear to have a prion-like mode of expansion in brains, such as in Alzheimer's or Parkinson's diseases. To date, the resolution of prion structure remains elusive. Thus, to genetically define the landscape of regions critical for prion conversion, we tested the effect of short deletions. We found that, surprisingly, removal of a portion of PrP, the C terminus of alpha-helix H2, did not hamper prion formation but generated infectious agents with an internal deletion that showed characteristics essentially similar to those of original infecting strains. Thus, we demonstrate that completeness of the residues inside prions is not necessary for maintaining infectivity and the main strain-specific information, while reporting one of the few if not the only bona fide prions with an internal deletion. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
Electrostatics of a Family of Conducting Toroids
Lekner, John
2009-01-01
An exact solution is found for the electrostatic potential of a family of conducting charged toroids. The toroids are characterized by two lengths "a" and "b", with "a" greater than or equal to "2b". They are closed, with no hole in the "doughnut". The results are obtained by considering the potential of two equal charges, displaced from the…
Fast Dump of the ATLAS Toroids
Dudarev, A; Volpini, Giovanni; Dudarev, Alexey; Kate, Herman Ten
2010-01-01
The toroidal magnet system of the ATLAS Detector at CERN consists of a Barrel Toroid (BT) and two End Cap Toroids (ECT-A and ECT-C). Each toroid is built up from eight racetrack coils wound with an aluminum stabilized NbTi conductor and indirectly cooled by forced flow liquid helium. The three toroids operate in series at 20.5 kA with a total stored energy of 1.5 GJ. In order to verify the reliability and effectiveness of the quench protection system, series of fast dump tests have been performed first of the single toroids and finally of the entire toroidal magnet system. In this paper a model to simulate the fast dump of the ATLAS toroids in single mode operation and in full system configuration is presented. The model is validated through comparison with measured data extracted from the ramp-and-quench runs. The calculated energy dissipation in the various coils is in very good agreement (within 1-2\\%) with the enthalpy changes estimated from the temperature measurements of the different parts of the cold ...
Steady state toroidal magnetic field at earth's core-mantle boundary
Levy, Eugene H.; Pearce, Steven J.
1991-01-01
Measurements of the dc electrical potential near the top of earth's mantle have been extrapolated into the deep mantle in order to estimate the strength of the toroidal magnetic field component at the core-mantle interface. Recent measurements have been interpreted as indicating that at the core-mantle interface, the magnetic toroidal and poloidal field components are approximately equal in magnitude. A motivation for such measurements is to obtain an estimate of the strength of the toroidal magnetic field in the core, a quantity important to our understanding of the geomagnetic field's dynamo generation. Through the use of several simple and idealized calculation, this paper discusses the theoretical relationship between the amplitude of the toroidal magnetic field at the core-mantle boundary and the actual amplitude within the core. Even with a very low inferred value of the toroidal field amplitude at the core-mantle boundary, (a few gauss), the toroidal field amplitude within the core could be consistent with a magnetohydrodynamic dynamo dominated by nonuniform rotation and having a strong toroidal magnetic field.
OCLATOR (One Coil Low Aspect Toroidal Reactor)
Energy Technology Data Exchange (ETDEWEB)
Yoshikawa, S.
1980-02-01
A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the ..beta.. limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR (One Coil Low Aspect Toroidal Reactor).
Toroidal effects on drift wave turbulence
Energy Technology Data Exchange (ETDEWEB)
LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.
1992-09-23
The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling.
Toroidal effects on drift wave turbulence
International Nuclear Information System (INIS)
LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.
1992-01-01
The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling
Fifth generation computer systems. Proceedings of the International conference
Energy Technology Data Exchange (ETDEWEB)
Moto-oka, T
1982-01-01
The following topics were dealt with: Fifth Generation Computer Project-social needs and impact; knowledge information processing research plan; architecture research plan; knowledge information processing topics; fifth generation computer architecture considerations.
Production of internal transport barriers via self-generated mean flows in Alcator C-Mod
Energy Technology Data Exchange (ETDEWEB)
Fiore, C. L.; Ernst, D. R.; Podpaly, Y. A.; Howard, N. T.; Lee, Jungpyo; Reinke, M. L.; Rice, J. E.; Hughes, J. W.; Ma, Y. [MIT-PSFC, 77 Mass. Ave., Cambridge, Massachusetts 02139 (United States); Mikkelsen, D. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Rowan, W. L.; Bespamyatnov, I. [FRC, U of Texas at Austin, Austin, Texas 78712 (United States)
2012-05-15
New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak [E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007)]. These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti Almost-Equal-To Te, and with monotonic q profiles (q{sub min} < 1). C-Mod H-mode plasmas exhibit strong intrinsic co-current rotation that increases with increasing stored energy without external drive. When the resonance position is moved off-axis, the rotation decreases in the center of the plasma resulting in a radial toroidal rotation profile with a central well which deepens and moves farther off-axis when the ICRF resonance location reaches the plasma half-radius. This profile results in strong E Multiplication-Sign B shear (>1.5 Multiplication-Sign 10{sup 5} rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.
Development of Toroidal Core Transformers
Energy Technology Data Exchange (ETDEWEB)
de Leon, Francisco [New York Univ. (NYU), Brooklyn, NY (United States). Dept. of Electrical and Computer Engineering
2014-08-01
The original objective of this project was to design, build and test a few prototypes of single-phase dry-type distribution transformers of 25 kVA, 2.4 kV primary to 120 V transformers using cores made of a continuous steel strip shaped like a doughnut (toroid). At different points during the development of the project, the scope was enhanced to include the more practical case of a 25 kVA transformer for a 13.8 kV primary system voltage. Later, the scope was further expanded to design and build a 50 kVA unit to transformer voltage from 7.62 kV to 2x120 V. This is a common transformer used by Con Edison of New York and they are willing to test it in the field. The project officially started in September 2009 and ended in May 2014. The progress was reported periodically to DOE in eighteen quarterly reports. A Continuation Application was submitted to DOE in June 2010. In May 2011 we have requested a non-cost extension of the project. In December 2011, the Statement of Project Objectives (SOPO) was updated to reflect the real conditions and situation of the project as of 2011. A second Continuation Application was made and funding was approved in 2013 by DOE and the end date was extended to May 2014. The technical challenges that were overcome in this project include: the development of the technology to pass the impulse tests, derive a model for the thermal performance, produce a sound mechanical design, and estimate the inrush current. However, the greatest challenge that we faced during the development of the project was the complications of procuring the necessary parts and materials to build the transformers. The actual manufacturing process is relatively fast, but getting all parts together is a very lengthy process. The main products of this project are two prototypes of toroidal distribution transformers of 7.62 kV (to be used in a 13.8 kV system) to 2x120 V secondary (standard utilization voltage); one is rated at 25 kVA and the other at 50 kVA. The 25 k
Influence of external toroidal flux on low-aspect-ratio toroidal plasma
International Nuclear Information System (INIS)
Ikuno, S.; Natori, M.; Kamitani, A.
1999-01-01
In the HIST device, the external flux is generated by two kinds of currents: the current I s flowing along the symmetry axis and the bias coil current I D . The influence of the external flux on the MHD equilibrium and stability of the low-aspect-ratio toroidal plasma in the HIST device is investigated numerically. Equilibrium configurations of the low-aspect-ratio toroidal plasma in the HIST device are numerically determined by means of the combination of FDM and BEM. The influence of I s and I D on their stability is also investigated by using the Mercier criterion. The results of computations show that the Mercier limit decreases to zero with increasing I s and with decreasing I D . Moreover, either a further increase in I s or a further decrease in I D raises the Mercier limit considerably. Besides, the equilibrium configuration in the HIST device changes its state from spheromak through ultra-low q to tokamak with increasing I s and with decreasing I D . (author)
IMECCHI-DATANETWORK: empowering knowledge generation through international data network
Directory of Open Access Journals (Sweden)
Marie Annick Le Pogam
2017-04-01
Within the IMECCHI-DATANETWORK initiative, databases from various countries will be locally converted in a CDM which will facilitate study replication in a distributed fashion while granting interoperability across coding systems. Through such international data networks, data are empowered for creating results which are generalizable to multiple countries. Cross-border data sharing and international comparisons are also facilitated.
KINEMATICAL FEATURES OF FORMATION OF A FLANGE WITH MINIMUM TENSION OF A TRANSIENT TOROIDAL SURFACE
Directory of Open Access Journals (Sweden)
M. I. Sidorenko
2018-01-01
Full Text Available The technology of plastic forming of wide flanges in tube billets with the predicted length of the transitional toroidal section between the outer plane of the flange and the internal cavity of the pipe is proposed. The procedure for calculating the length of this section is given. In order to eliminate the toroidal portion in the flange formed during the flanging of the pipe, it is proposed to perform its plastic shaping by depositing the cylindrical part of the workpiece. Equations for calculating the extent of the free surface on the toroidal part of the workpiece when it is shaped, depending on the coefficient of contact friction and the presence of a radial support of the flange are obtained. The variant of forming in the flange the toroidal section in the stamp with the compensation cavity is proposed. Equations for calculating the deformation force and the extent of the free surface are given.
NCSX Toroidal Field Coil Design
International Nuclear Information System (INIS)
Kalish M; Rushinski J; Myatt L; Brooks A; Dahlgren F; Chrzanowski J; Reiersen W; Freudenberg K.
2005-01-01
The National Compact Stellarator Experiment (NCSX) is an experimental device whose design and construction is underway at the Department of Energy's Princeton Plasma Physics Laboratory (PPPL). The primary coil systems for the NCSX device consist of the twisted plasma-shaping Modular Coils, the Poloidal Field Coils, and the Toroidal Field (TF) Coils. The TF Coils are D-shaped coils wound from hollow copper conductor, and vacuum impregnated with a glass-epoxy resin system. There are 18 identical, equally spaced TF coils providing 1/R field at the plasma. They operate within a cryostat, and are cooled by LN2, nominally, to 80K. Wedge shaped castings are assembled to the inboard face of these coils, so that inward radial loads are reacted via the nesting of each of the coils against their adjacent partners. This paper outlines the TF Coil design methodology, reviews the analysis results, and summarizes how the design and analysis support the design requirements
Quasistatic evolution of compact toroids
International Nuclear Information System (INIS)
Sgro, A.G.; Spencer, R.L.; Lilliequist, C.
1981-01-01
Some results are presented of simulations of the post formation evolution of compact toroids. The simulations were performed with a 1-1/2 D transport code. Such a code makes explicit use of the fact that the shapes of the flux surfaces in the plasma change much more slowly than do the profiles of the physical variables across the flux surfaces. Consequently, assuming that the thermodynamic variables are always equilibrated on a flux surface, one may calculate the time evolution of these profiles as a function of a single variable that labels the flux surfaces. Occasionally, during the calculation these profiles are used to invert the equilibrium equation to update the shapes of the flux surfaces. In turn, these shapes imply certain geometric cofficients, such as A = 2 >, which contain the geometric information required by the 1-D equations
Runaway electrons in toroidal discharges
International Nuclear Information System (INIS)
Knoepfel, H.
1979-01-01
Experimental and theoretical studies of runaway electrons in toroidal devices are reviewed here, with particular reference to tokamaks. The complex phenomenology of runaway effects, which have been the subject of research for the past twenty years, is organized within the framework of a number of physical models. The mechanisms and rates for runaway production are discussed first, followed by sections on runaway-driven kinetic relaxation processes and runaway orbit confinement. Next, the equilibrium and stability of runaway-dominated discharges are reviewed. Models for runaway production at early times in the discharge and the scaling of runaway phenomena to larger devices are also discussed. Finally, detection techniques and possible applications of runaways are mentioned. (author)
International Nuclear Information System (INIS)
Ida, Katsumi
2001-01-01
The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in toroidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasma because of the helicity of symmetry of the magnetic field configuration. (author)
A novel method of generating and remembering international morse codes
Digital Repository Service at National Institute of Oceanography (India)
Charyulu, R.J.K.
untethered communications have been advanced, despite as S.O.S International Morse Code will be at rescue as an emergency tool, when all other modes fail The details of hte method and actual codes have been enumerated....
A comparison between linear and toroidal Extrap systems
International Nuclear Information System (INIS)
Lehnert, B.
1988-09-01
The Extrap scheme consists of a Z-pinch immersed in an octupole field generated by currents in a set of external conductors. A comparison between linear and toroidal Extrap geometry is made in this paper. As compared to toroidal systems, linear geometry has the advantages of relative simplicity and of a current drive by means of electrodes. Linear devices are convenient for basic studies of Extrap, at moderately high pinch currents and plasma temperatures. Within the parameter ranges of experiments at high pinch currents and plasma temperatures, linear systems have on the other hand some substantial disadvantages, on account of the plasma interaction with the end regions. This results in a limitation of the energy confinement time, and leads in the case of an ohmically heated plasma to excessively high plasma densities and small pinch radii which also complicate the introduction of the external conductors. (author)
Progress of international cooperation of nuclear power generation
International Nuclear Information System (INIS)
Sasaki, Sadaaki; Ishikawa, Hidetaka; Eda, Hisao; Noda, Hiroshi; Kobayashi, Ichiro; Kawahara, Akira; Nagano, Akira
1999-01-01
International cooperation on nuclear power technology under promotion of the Japan Electric Power Information Center can be divided roughly to two items: one is an assistant project of Japan Keirin Association and another is an international training of operation management and so forth on nuclear power plant trusted by Ministry of International Trade and Industry. Among upgrading needs of technical cooperation on nuclear power to the developing nations, the electric companies were received a request on private cooperation by the Ministry of International Trade and Industry. In 1985, it was decided that the nuclear power technical cooperation through an subsidy project of the Japan Keirin Association was advanced mainly by every electric companies as a window of the Japan Electric Power Information Center in Japan Electric Industry Association. And, by receiving another request, the Japan Electric Power Information Center began an international training on operation management and so one of the nuclear power plant since October, 1992. Here were introduced outlines of both technical cooperation on nuclear power and international training on operation management. (G.K.)
Compact toroid formation, compression, and acceleration
International Nuclear Information System (INIS)
Degnan, J.H.; Peterkin, R.E. Jr.; Baca, G.P.; Beason, J.D.; Bell, D.E.; Dearborn, M.E.; Dietz, D.; Douglas, M.R.; Englert, S.E.; Englert, T.J.; Hackett, K.E.; Holmes, J.H.; Hussey, T.W.; Kiuttu, G.F.; Lehr, F.M.; Marklin, G.J.; Mullins, B.W.; Price, D.W.; Roderick, N.F.; Ruden, E.L.; Sovinec, C.R.; Turchi, P.J.; Bird, G.; Coffey, S.K.; Seiler, S.W.; Chen, Y.G.; Gale, D.; Graham, J.D.; Scott, M.; Sommars, W.
1993-01-01
Research on forming, compressing, and accelerating milligram-range compact toroids using a meter diameter, two-stage, puffed gas, magnetic field embedded coaxial plasma gun is described. The compact toroids that are studied are similar to spheromaks, but they are threaded by an inner conductor. This research effort, named MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation), is not a magnetic confinement fusion program like most spheromak efforts. Rather, the ultimate goal of the present program is to compress toroids to high mass density and magnetic field intensity, and to accelerate the toroids to high speed. There are a variety of applications for compressed, accelerated toroids including fast opening switches, x-radiation production, radio frequency (rf) compression, as well as charge-neutral ion beam and inertial confinement fusion studies. Experiments performed to date to form and accelerate toroids have been diagnosed with magnetic probe arrays, laser interferometry, time and space resolved optical spectroscopy, and fast photography. Parts of the experiment have been designed by, and experimental results are interpreted with, the help of two-dimensional (2-D), time-dependent magnetohydrodynamic (MHD) numerical simulations. When not driven by a second discharge, the toroids relax to a Woltjer--Taylor equilibrium state that compares favorably to the results of 2-D equilibrium calculations and to 2-D time-dependent MHD simulations. Current, voltage, and magnetic probe data from toroids that are driven by an acceleration discharge are compared to 2-D MHD and to circuit solver/slug model predictions. Results suggest that compact toroids are formed in 7--15 μsec, and can be accelerated intact with material species the same as injected gas species and entrained mass ≥1/2 the injected mass
Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta
International Nuclear Information System (INIS)
Schlossberg, David J.; Bodner, Grant M.; Bongard, Michael W.; Burke, Marcus G.; Fonck, Raymond J.
2017-01-01
Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-to-magnetic pressure ratio (β t ), low internal inductance, high elongation, and nonsolenoidal current drive is a central goal of present tokamak plasma research. Stable access to this desirable parameter space is demonstrated in plasmas with ultralow aspect ratio and high elongation. Local helicity injection provides nonsolenoidal sustainment, low internal inductance, and ion heating. Equilibrium analyses indicate β t up to ~100% with a minimum |B| well spanning up to ~50% of the plasma volume.
Unified kinetic theory in toroidal systems
International Nuclear Information System (INIS)
Hitchcock, D.A.; Hazeltine, R.D.
1980-12-01
The kinetic theory of toroidal systems has been characterized by two approaches: neoclassical theory which ignores instabilities and quasilinear theory which ignores collisions. In this paper we construct a kinetic theory for toroidal systems which includes both effects. This yields a pair of evolution equations; one for the spectrum and one for the distribution function. In addition, this theory yields a toroidal generalization of the usual collision operator which is shown to have many similar properties - conservation laws, H theorem - to the usual collision operator
Numerical determination of axisymmetric toroidal magnetohydrodynamic equilibria
International Nuclear Information System (INIS)
Johnson, J.L.; Dalhed, H.E.; Greene, J.M.
1978-07-01
Numerical schemes for the determination of stationary axisymmetric toroidal equilibria appropriate for modeling real experimental devices are given. Iterative schemes are used to solve the elliptic nonlinear partial differential equation for the poloidal flux function psi. The principal emphasis is on solving the free boundary (plasma-vacuum interface) equilibrium problem where external current-carrying toroidal coils support the plasma column, but fixed boundary (e.g., conducting shell) cases are also included. The toroidal current distribution is given by specifying the pressure and either the poloidal current or the safety factor profiles as functions of psi. Examples of the application of the codes to tokamak design at PPPL are given
Rotating bubble and toroidal nuclei and fragmentation
International Nuclear Information System (INIS)
Royer, G.; Haddad, F.; Jouault, B.
1995-01-01
The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy-ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. The potential barriers standing in these exotic deformation paths are compared with the three dimensional and plane fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localised below the plane fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension. (author)
Toroidal field ripple effects in large tokamaks
International Nuclear Information System (INIS)
Uckan, N.A.; Tsang, K.T.; Callen, J.D.
1975-01-01
In an experimental power reactor, the ripple produced by the finite number of toroidal field coils destroys the ideal axisymmetry of the configuration and is responsible for additional particle trapping, loss regions and plasma transport. The effects of toroidal field ripple on the plasma transport coefficient, the loss of alpha particles and energetic injection ions, and the relaxation of toroidal flows are investigated in a new and systematic way. The relevant results are applied to the ORNL-EPR reference design; the maximum ripple there of about 2.2 percent at the outer edge of the plasma column is found to be tolerable from plasma physics considerations
A Thermoelectric Generator Replacing Radiator for Internal Combustion Engine Vehicles
Directory of Open Access Journals (Sweden)
Shiho Kim
2011-12-01
Full Text Available We have proposed and developed a low temperature thermoelectric generator (TEG using engine water coolant of light-duty vehicles. Experimental results from test vehicle, of which engine size is about 2.0 liters, show that fabricated prototype Thermoelectric Generator generates more than 75W for driving condition of 80 km/hour, and output power is about 28W during idle condition. The proposed TEG can replace conventional radiator without additional water pumps or mechanical devices except for basic components of legacy water cooling system of radiator.
The Next Generation Information Infrastructure for International Trade
DEFF Research Database (Denmark)
Henningsson, Stefan; Gal, Uri; Bjørn-Andersen, Niels
2011-01-01
that are in control of their business. Trusted traders are entitled to trade facilitations, faster border crossing, and fewer physical inspections. To enable the use of trusted traders, changes are required to the information infrastructure (II) of international trade. This article complements existing works on e......-Government interoperability by a theoretically driven approach with theoretical development of the II concept and how II can be modified as additional focus. Following the principles of IS design research, this paper presents a design proposition for the II of international trade. Using theories of II development and change......Regulators and actors in international trade are facing a difficult challenge of increasing control and security while at the same time lowering the administrative burden for traders. As a tentative response, the European Commission has introduced the concept of “trusted traders”: certified traders...
Calculations of toroidal EXTRAP equilibria for different toroidal ring current configurations
International Nuclear Information System (INIS)
Drake, J.R.; Scheffel, J.
1985-12-01
EXTRAP is a concept in which a pure Z-pinch is generated along the axis of an octupole field. Experiments in a linear as well as in a sector geometry have demonstrated that the pinch becomes stable against instabilities for many Alfven times. The octupole field in EXTRAP is produced by four, external, current-carrying rings. In the toroidal geometry these rings must be supplemented by additional rings to compensate for the plasma loop force and transformer core leakage flux. Equilibrium studies are carried out for two basically ring designs. The studies are based on numerical equilibrium copmputations using the GOYA code. Sensitivity of the equilibrium to technical imperfections is also analyzed. (author)
Virtual Seafloor Reduces Internal Wave Generation by Tidal Flow
Zhang, Likun; Swinney, Harry L.
2014-03-01
Our numerical simulations of tidal flow of a stratified fluid over periodic knife-edge ridges and random topography reveal that the time-averaged tidal energy converted into internal gravity wave radiation arises only from the section of a ridge above a virtual seafloor. The average radiated power is approximated by the power predicted by linear theory if the height of the ridge is measured relative to the virtual floor. The concept of a virtual floor can extend the applicability of linear theory to global predictions of the conversion of tidal energy into internal wave energy in the oceans.
Neoclassical offset toroidal velocity and auxiliary ion heating in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Lazzaro, E., E-mail: lazzaro@ifp.cnr.it [Istituto di Fisica del Plasma CNR (Italy)
2016-05-15
In conditions of ideal axisymmetry, for a magnetized plasma in a generic bounded domain, necessarily toroidal, the uniform absorption of external energy (e.g., RF or any isotropic auxiliary heating) cannot give rise to net forces or torques. Experimental evidence on contemporary tokamaks shows that the near central absorption of RF heating power (ICH and ECH) and current drive in presence of MHD activity drives a bulk plasma rotation in the co-I{sub p} direction, opposite to the initial one. Also the appearance of classical or neoclassical tearing modes provides a nonlinear magnetic braking that tends to clamp the rotation profile at the q-rational surfaces. The physical origin of the torque associated with P{sub RF} absorption could be due the effects of asymmetry in the equilibrium configuration or in power deposition, but here we point out also an effect of the response of the so-called neoclassical offset velocity to the power dependent heat flow increment. The neoclassical toroidal viscosity due to internal magnetic kink or tearing modes tends to relax the plasma rotation to this asymptotic speed, which in absence of auxiliary heating is of the order of the ion diamagnetic velocity. It can be shown by kinetic and fluid calculations, that the absorption of auxiliary power by ions modifies this offset proportionally to the injected power thereby forcing the plasma rotation in a direction opposite to the initial, to large values. The problem is discussed in the frame of the theoretical models of neoclassical toroidal viscosity.
Toroidal Continuously Variable Transmission Systems: Terminology and Present Studies
Directory of Open Access Journals (Sweden)
Ahmet YILDIZ
2014-04-01
Full Text Available The use of continuously variable transmission systems in many different areas such as aerospace, robotics, machinery and automotive industries as an alternative to conventional speed changers with constant ratio becomes widely.Especially in the automotive industry, these systems have been used increasingly, since they enable that internal combustion engines in vehicles run at optimal speeds, and consequently provide considerable fuel savings and therefore lower emission values and also they provide powerful acceleration and quiet working. CVT systems have several constructive variants such as belted, chained, balled, toroidal etc. In this paper, toroidal CVT systems based on elastohydrodynamic principles are concerned with, and fundamental works of last two decades in this field are reviewed. However, the relevant terminology and dynamics along with the control of these systems are briefly treated for better understanding of the literature mentioned. Attention is drawn to the lack of some significant issues in present research works, and potential future works are pointed out. This paper, to the authors’ knowledge, will be the first review on toroidal CVT systems in Turkish literature
OCLATOR (One Coil Low Aspect Toroidal Reactor)
International Nuclear Information System (INIS)
Yoshikawa, S.
1980-02-01
A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the β limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR
Steady state compact toroidal plasma production
Turner, William C.
1986-01-01
Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.
LASL toroidal reversed-field pinch programme
International Nuclear Information System (INIS)
Baker, D.A.; Buchenauer, C.J.; Burkhardt, L.C.
1979-01-01
The determination of the absolute energy loss due to radiation from impurities in the LASL toroidal reversed-field pinch experiment ZT-S is reported. The measurements show that over half the energy loss is accounted for by this mechanism. Thomson-scattering electron density measurements indicate only a gradual increase in temperature as the filling pressure is reduced, indicating an increased energy loss at lower pressures. Cylindrical and toroidal simulations of the experiment indicate either that a highly radiative pinch boundary or anomalous transport is needed to match the experimental results. New effects on the equilibrium due to plasma flows induced by the toroidal geometry are predicted by the toroidal simulations. The preliminary results on the low-temperature discharge cleaning of the ZT-S torus are reported. A description of the upgrade of the ZT-S experiment and the objectives, construction and theoretical predictions for the new ZT-40 experiment are given. (author)
LASL toroidal reversed-field pinch program
International Nuclear Information System (INIS)
Baker, D.A.; Buchenauer, C.J.; Burkhardt, L.C.
1978-01-01
The determination of the absolute energy loss due to radiation from impurities in the LASL toroidal reversed-field pinch experiment ZT-S is reported. The measurements show over half of the energy loss is accounted for by this mechanism. Thomson scattering electron density measurements indicate only a gradual increase in temperature as the filling pressure is reduced indicating an increased energy loss at lower pressures. Cylindrical and toroidal simulations of the experiment indicate either that a highly radiative pinch boundary or anomalous transport are needed to match the experimental results. New effects on the equilibrium due to plasma flows induced by the toroidal geometry are predicted by the toroidal simulations. The preliminary results on the low temperature discharge cleaning of the ZT-S torus are reported. A description of the upgrade of the ZT-S experiment and the objectives, construction and theoretical predictions for the new ZT-40 experiment are given
Influence of toroidal rotation on tearing modes
Cai, Huishan; Cao, Jintao; Li, Ding
2017-10-01
Tearing modes stability analysis including toroidal rotation is studied. It is found that rotation affects the stability of tearing modes mainly through the interaction with resistive inner region of tearing mode. The coupling of magnetic curvature with centrifugal force and Coriolis force provides a perturbed perpendicular current, and a return parallel current is induced to affect the stability of tearing modes. Toroidal rotation plays a stable role, which depends on the magnitude of Mach number and adiabatic index Γ, and is independent on the direction of toroidal rotation. For Γ >1, the scaling of growth rate is changed for typical Mach number in present tokamaks. For Γ = 1 , the scaling keeps unchanged, and the effect of toroidal rotation is much less significant, compared with that for Γ >1. National Magnetic Confinement Fusion Science Program and National Science Foundation of China under Grants No. 2014GB106004, No. 2013GB111000, No. 11375189, No. 11075161 and No. 11275260, and Youth Innovation Promotion Association CAS.
Bow-shaped toroidal field coils
International Nuclear Information System (INIS)
Bonanos, P.
1981-05-01
Design features of Bow-Shaped Toroidal Field Coils are described and compared with circular and D shaped coils. The results indicate that bow coils can produce higher field strengths, store more energy and be made demountable. The design offers the potential for the production of ultrahigh toroidal fields. Included are representative coil shapes and their engineering properties, a suggested structural design and an analysis of a specific case
Unstable universal drift eigenmodes in toroidal plasmas
International Nuclear Information System (INIS)
Cheng, C.Z.; Chen, L.
1979-08-01
The eigenmode equation describing ballooning collisionless drift instabilities is analyzed both analytically and numerically. A new branch of eigenmodes, which corresponds to quasi-bound states due to the finite toroidicity, is shown to be destabilized by electron Landau damping for typical Tokamak parameters. This branch cannot be understood by the strong coupling approximation. However, the slab-like (Pearlstein-Berk type) branch is found to remain stable and experience enhanced shear damping due to finite toroidicity
Spherical tokamak without external toroidal fields
International Nuclear Information System (INIS)
Kaw, P.K.; Avinash, K.; Srinivasan, R.
2001-01-01
A spherical tokamak design without external toroidal field coils is proposed. The tokamak is surrounded by a spheromak shell carrying requisite force free currents to produce the toroidal field in the core. Such equilibria are constructed and it is indicated that these equilibria are likely to have robust ideal and resistive stability. The advantage of this scheme in terms of a reduced ohmic dissipation is pointed out. (author)
Viscous damping of toroidal angular momentum in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Stacey, W. M. [Georgia Tech Fusion Research Center, Atlanta, Georgia 30332 (United States)
2014-09-15
The Braginskii viscous stress tensor formalism was generalized to accommodate non-axisymmetric 3D magnetic fields in general toroidal flux surface geometry in order to provide a representation for the viscous damping of toroidal rotation in tokamaks arising from various “neoclassical toroidal viscosity” mechanisms. In the process, it was verified that the parallel viscosity contribution to damping toroidal angular momentum still vanishes even in the presence of toroidal asymmetries, unless there are 3D radial magnetic fields.
Low-n shear Alfven spectra in axisymmetric toroidal plasmas
International Nuclear Information System (INIS)
Cheng, C.Z.; Chance, M.S.
1985-11-01
In toroidal plasmas, the toroidal magnetic field is nonuniform over a magnetic surface and causes coupling of different poloidal harmonics. It is shown both analytically and numerically that the toroidicity not only breaks up the shear Alfven continuous spectrum, but also creates new, discrete, toroidicity-induced shear Alfven eigenmodes with frequencies inside the continuum gaps. Potential applications of the low-n toroidicity-induced shear Alfven eigenmodes on plasma heating and instabilities are addressed. 17 refs., 4 figs
Celebrating the Barrel Toroid commissioning
Peter Jenni
ATLAS invited Funding Agency representatives and Laboratory Heads directly related to the funding and construction of the Barrel Toroid for a small ceremony on 13th December 2006 at Point 1, in order to mark the successful first full excitation of the BT (see last eNews). On that date, which was during the December CERN Council week, several of the Funding Agency Heads or their representatives could be present, representing CEA France, INFN Italy, BMBF Germany, Spain, Sweden, Switzerland, Russia, JINR Dubna and CERN. Speeches were delivered by the ATLAS spokesperson Peter Jenni thanking the Funding Partners in the name of the Collaboration, by Magnet Project Leader Herman ten Kate tracing the BT construction history, and by the CERN Director-General Robert Aymar congratulating all those who have contributed to the successful project. Herman ten Kate addressing the delegates. The text of the introductory address by Peter Jenni is reproduced here. "It is a great pleasure for me to welcome you all here...
Anomalous transport in toroidal plasmas
International Nuclear Information System (INIS)
Punjabi, A.
1989-12-01
When the magnetic moment of particle is conserved, there are three mechanisms which cause anomalous transport. These are: variation of magnetic field strength in flux surface, variation of electrostatic potential in flux surface, and destruction of flux surface. The anomalous transport of different groups of particles resulting from each of these mechanisms is different. This fact can be exploited to determine the cause of transport operative in an experimental situation. This approach can give far more information on the transport than the standard confinement time measurements. To implement this approach, we have developed Monte Carlo codes for toroidal geometries. The equations of motion are developed in a set of non-canonical, practical Boozer co-ordinates by means of Jacobian transformations of the particle drift Hamiltonian equations of motion. Effects of collisions are included by appropriate stochastic changes in the constants of motion. Effects of the loop voltage on particle motions are also included. We plan to apply our method to study two problems: the problem of the hot electron tail observed in edge region of ZT-40, and the energy confinement time in TOKAPOLE II. For the ZT-40 problem three situations will be considered: a single mode in the core, a stochastic region that covers half the minor radius, a stochastic region that covers the entire plasma. A turbulent spectrum of perturbations based on the experimental data of TOKAPOLE II will be developed. This will be used to simulate electron transport resulting from ideal instabilities and resistive instabilities in TOKAPOLE II
Anomalous transport in toroidal plasmas
International Nuclear Information System (INIS)
Punjabi, A.
1991-01-01
We have developed a Monte Carlo method to estimate the transport of different groups of particles for plasmas in toroidal geometries. This method can determine the important transport mechanisms driving the anomalous transport by comparing the numerical results with the experimental data. The important groups of particles whose transport can be estimated by this method include runaway electrons, thermal electrons, both passing and trapped diagnostic beam ions etc. The three basic mechanisms driving the anomalous transport are: spatial variation of magnetic field strength, spatial variation of electrostatic potential within the flux surfaces, and the loss of flux surfaces. The equation of motion are obtained from the drift hamiltonian. The equations of motion are developed in the canonical and in the non-canonical, practical co-ordinates as well. The effects of collisions are represented by appropriate stochastic changes in the constants of motion at each time-step. Here we present the results of application of this method to three cases: superathermal alphas in the rippled field of tokamaks, motion in the magnetic turbulence of takapole II, and transport in the stochastic fields of ZT40. This work is supported by DOE OFE and ORAU HBCU program
Does the internet generate economic growth, international trade, or both?
Meijers, Huub
2012-01-01
Recent cross country panel data studies find a positive impact of internet use on economic growth and a positive impact of internet use on trade. The present study challenges the first finding by showing that internet use does not explain economic growth directly in a fully specified growth model. In particular openness to international trade variables seems to be highly correlated with internet use and the findings in the literature that internet use causes trade is confirmed here, suggestin...
Toroidal plasma reactor with low external magnetic field
International Nuclear Information System (INIS)
Beklemishev, A.D.; Khayrutdinov, R.R.; Petviashvili, V.I.; Tajima, T.; Gordin, V.A.; Tajima, T.
1991-01-01
A toroidal pinch configuration with safety factor q < 0.5 decreasing from the center to periphery without field reversal is proposed. This is capable of containing high pressure plasma with only small toroidal external magnetic field. Sufficient conditions for magnetohydrodynamic stability are fulfilled in this configuration. The stability is studied by constructing the Lyapunov functional and investigating its extrema both analytically and numerically. Comparison of the Lyapunov stability conditions with the conventional linear theory is carried out. Stable configurations are found with average β near 15%, with magnetic field associated mainly with plasma current. The β value calculated with the external magnetic field can be over 100%. Fast charged particles produced by fusion reactions are asymmetrically confined by the poloidal magnetic field (and due to the lack of strong toroidal field). They thus generate a current in the noncentral part of plasma to reinforce the poloidal field. This current drive can sustain the monotonic decrease of q with radius. 20 refs., 9 figs
G20: Engaging with International Organizations to Generate Growth
Directory of Open Access Journals (Sweden)
Marina Larionova
2017-08-01
Full Text Available Born in response to economic and financial crises which existing institutions were unable to address adequately, the G20 transformed from a crisis management group into the premier forum for international economic cooperation. Like its predecessor, the G7 (which was set up in 1975, and BRICS (established in 2009, G20 is an informal club or summit institution. To ensure continuity, legitimacy and efficiency in fulfilling their global governance functions of deliberation, direction-setting, decision-making, delivery and the development of global governance, the G20 members engage other international organizations. It is hypothesized that to maximize benefits from its engagement with international organizations, the G20 resorts to a combination of the “catalyst”, “core group” and “parallel treatment” approaches exercised by summit institutions. These include exerting an influence in promoting changes to international organizations through endorsement or stimulus, compelling them to reform, imparting a new direction by giving a lead that the other organizations would follow, and creating original mechanisms, working in parallel with existing institutions. The article tests this assumption. To trace the dynamics of G20 engagement with multilateral organizations and identify preferred models across the presidencies and policy areas, the analysis is carried out within the rational choice institutionalist paradigm, drawing on the quantitative and qualitative analysis of documents adopted by the G20. Findings from the study indicate that the intensity of the G20 engagement with the IOs is very high and G20 mostly resorts to a combination of the catalyst and core group approaches, though the pattern depends on the policy area, the IOs and the presidency agenda. The intensity of G20 engagement with the IMF, Financial Stability Board, World Bank, and Organization for Economic Co-operation and Development by far exceeds the intensity of its
Biomass Gasification for Power Generation Internal Combustion Engines. Process Efficiency
International Nuclear Information System (INIS)
Lesme-Jaén, René; Garcia-Faure, Luis; Oliva-Ruiz, Luis; Pajarín-Rodríguez, Juan; Revilla-Suarez, Dennis
2016-01-01
Biomass is a renewable energy sources worldwide greater prospects for its potential and its lower environmental impact compared to fossil fuels. By different processes and energy conversion technologies is possible to obtain solid, liquid and gaseous fuels from any biomass.In this paper the evaluation of thermal and overall efficiency of the gasification of Integral Forestry Company Santiago de Cuba is presented, designed to electricity generation from waste forest industry. The gasifier is a downdraft reactor, COMBO-80 model of Indian manufacturing and motor (diesel) model Leyland modified to work with producer gas. The evaluation was conducted at different loads (electric power generated) of the motor from experimental measurements of flow and composition of gas supplied to the engine. The results show that the motor operates with a thermal efficiency in the range of 20-32% with an overall efficiency between 12-25 %. (author)
Network integration of distributed generation: international research and development
Energy Technology Data Exchange (ETDEWEB)
Watson, J.
2003-07-01
This report provides information on privately and publicly funded research and development programmes in distributed generation (DG) in the USA, the European Union and Japan. Protection systems for the installation of DG, power electronics for the connection of DG to electricity distribution systems, reliability modelling, power quality issues, connection standards, and simulation and computer modelling are examined. The relevance of the programmes to the UK is considered.
Experimental investigation of natural convection induced by internal heat generation
International Nuclear Information System (INIS)
Tasaka, Y; Kudoh, Y; Takeda, Y; Yanagisawa, T
2005-01-01
Dilatation of a convection cell with respect to its Rayleigh number, one of the problems in internally heated convection, was quantitatively investigated by analyzing temperature field in a cell. The temperature field visualized by a thermo-chromic liquid crystal (TLC) expresses the cell dilatation. A calibration system was developed to convert the visualized photographs of the temperature field to the temperature field. A calibration curve correlating color information extracted from the photograph and temperature was determined from the approximately linear temperature distribution in the horizontal fluid layer using the hue method. Photos taken at various internal Rayleigh numbers were converted to the temperature field by the obtained curve. Extracting individual cells from a temperature field achieves a quantitative expression of the cell dilatation as the variation of the wavenumber of the cell with Rayleigh number increases. The temperature profile in a cell shows that high temperature areas appear at the apexes of the cell, largely different from the profile obtained by linear theory
Production of internal transport barriers via self-generated mean flows in Alcator C-Moda)
Fiore, C. L.; Ernst, D. R.; Podpaly, Y. A.; Mikkelsen, D.; Howard, N. T.; Lee, Jungpyo; Reinke, M. L.; Rice, J. E.; Hughes, J. W.; Ma, Y.; Rowan, W. L.; Bespamyatnov, I.
2012-05-01
New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak [E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007)]. These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti ≈ Te, and with monotonic q profiles (qmin 1.5 × 105 rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.
Analysis of the internal heat losses in a thermoelectric generator
DEFF Research Database (Denmark)
Bjørk, Rasmus; Christensen, Dennis Valbjørn; Eriksen, Dan
2014-01-01
and radiative heat losses, including surface to surface radiation. For radiative heat losses it is shown that for the temperatures considered here, surface to ambient radiation is a good approximation of the heat loss. For conductive heat transfer the module efficiency is shown to be comparable to the case...... of radiative losses. Finally, heat losses due to internal natural convection in the module is shown to be negligible for the millimetre sized modules considered here. The combined case of radiative and conductive heat transfer resulted in the lowest efficiency. The optimized load resistance is found...... to decrease for increased heat loss. The leg dimensions are varied for all heat losses cases and it is shown that the ideal way to construct a TEG module with minimal heat losses and maximum efficiency is to either use a good insulating material between the legs or evacuate the module completely, and use...
Electronic Commerce – An International Phenomenon, Generating Commercial Litigations
Directory of Open Access Journals (Sweden)
Angelica Roşu
2012-05-01
Full Text Available Although the e-commerce boom of the past few years has produced plenty of satisfied e-shoppersand successful Web-based companies, many consumers and businesses are left wondering where they can goto resolve their online disputes. The legal system (such as the court system and classical arbitration cannoteffectively respond to the challenges posed by conducting electronic commerce and this paper is proposed toanalyse the types of disputes that can arise from those e-commerce operations. The aim of this approach isrepresented by our attempt to explain why conflict resolution cannot be reasonably accomplished usingtraditional legal system and consequently the measures that have been taken by the international bodies tofacilitate consumers' right to a fair and effective trial services.
International Nuclear Information System (INIS)
Venkataraman, N.S.; Cardoso, H.P.; Oliveira Filho, O.B. de
1981-01-01
The conductive heat transfer in a rectangular plate with nonuniform internal heat generation, with one end convectively cooled and a part of the opposite end subjected to external heat flux is considered. The remaining part of this end as well as the other two sides are thermally insulated. The governing differential equation is solved by a finite difference scheme. The variation of the thermal resistance with Biot modulus, the plate geometry, the internal heat generation parameter and the type of profile of internal heat generation is discussed. (author) [pt
Resistive demountable toroidal-field coils for tokamak reactors
International Nuclear Information System (INIS)
Jassby, D.L.; Jacobsen, R.A.; Kalnavarns, J.; Masson, L.S.; Sekot, J.P.
1981-07-01
Readily demountable TF (toroidal-field) coils allow complete access to the internal components of a tokamak reactor for maintenance of replacement. The requirement of readily demountable joints dictates the use of water-cooled resistive coils, which have a host of decisive advantages over superconducting coils. Previous papers have shown that resistive TF coils for tokamak reactors can operate in the steady state with acceptable power dissipation (typically, 175 to 300 MW). This paper summarizes results of parametric studies of size optimization of rectangular TF coils and of a finite-element stress analysis, and examines several candidate methods of implementing demountable joints for rectangular coils constructed of plate segments
Evidence of Inward Toroidal Momentum Convection in the JET Tokamak
DEFF Research Database (Denmark)
Tala, T.; Zastrow, K.-D.; Ferreira, J.
2009-01-01
Experiments have been carried out on the Joint European Torus tokamak to determine the diffusive and convective momentum transport. Torque, injected by neutral beams, was modulated to create a periodic perturbation in the toroidal rotation velocity. Novel transport analysis shows the magnitude...... and profile shape of the momentum diffusivity are similar to those of the ion heat diffusivity. A significant inward momentum pinch, up to 20 m/s, has been found. Both results are consistent with gyrokinetic simulations. This evidence is complemented in plasmas with internal transport barriers....
Report on the international workshop on next generation linear colliders
International Nuclear Information System (INIS)
Ruth, R.D.
1989-05-01
Many laboratories around the world have begun vigorous research programs on a next generation linear collider (NLC). However, it has been recognized that the research towards NLC is beyond the capabilities of any one laboratory presently. This workshop was organized to begin a series of workshops that address this problem. Specifically, the main goals of the workshop were to discuss research programs of the various laboratories around the world, to identify common areas of interest in the various NLC designs, and finally to advance these programs by collaboration. The particular topics discussed briefly in this paper are: parameters, rf power, structures, final focus, beam dynamics, damping rings, and instrumentation. 2 refs., 3 figs., 6 tabs
Inspiring the Next Generation: The International Space Station Education Accomplishments
Alleyne, Camille W.; Hasbrook, Pete; Knowles, Carolyn; Chicoine, Ruth Ann; Miyagawa, Yayoi; Koyama, Masato; Savage, Nigel; Zell, Martin; Biryukova, Nataliya; Pinchuk, Vladimir;
2014-01-01
The International Space Station (ISS) has a unique ability to capture the imagination of both students and teachers worldwide. Since 2000, the presence of humans onboard ISS has provided a foundation for numerous educational activities aimed at capturing that interest and motivating study in the sciences, technology, engineering and mathematics (STEM). Over 43 million students around the world have participated in ISS-related educational activities. Projects such as YouTube Space Lab, Sally Ride Earth Knowledge-based Acquired by Middle Schools (EarthKAM), SPHERES (Synchronized Position Hold Engage and Reorient Experimental Satellites) Zero-Robotics, Tomatosphere, and MAI-75 events among others have allowed for global student, teacher and public access to space through student classroom investigations and real-time audio and video contacts with crewmembers. Educational activities are not limited to STEM but encompass all aspects of the human condition. This is well illustrated in the Uchu Renshi project, a chain poem initiated by an astronaut while in space and continued and completed by people on Earth. With ISS operations now extended to 2024, projects like these and their accompanying educational materials are available to more students around the world. From very early on in the program's history, students have been provided with a unique opportunity to get involved and participate in science and engineering projects. Many of these projects support inquiry-based learning that allows students to ask questions, develop hypothesis-derived experiments, obtain supporting evidence and identify solutions or explanations. This approach to learning is well-published as one of the most effective ways to inspire students to pursue careers in scientific and technology fields. Ever since the first space station element was launched, a wide range of student experiments and educational activities have been performed, both individually and collaboratively, by all the
Long-wavelength microinstabilities in toroidal plasmas
International Nuclear Information System (INIS)
Tang, W.W.; Rewoldt, G.
1993-01-01
Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities
Internally generated natural variability of global-mean temperatures
International Nuclear Information System (INIS)
Wigley, T.M.L.; Raper, S.C.B.
1990-01-01
Quantitative frequency-domain and time-domain estimates are made of an important aspect of natural variability of global-mean temperatures, namely, passive internal variability resulting from the modulation of atmospheric variability by the ocean. The results are derived using an upwelling-diffusion, energy-balance climate model. In the frequency domain, analytical spectral results show a transition from a high-frequency region in which the response is determined by the mixed-layer heat capacity and is independent of the climate sensitivity (time scales less than around 10 years), to a low-frequency region in which the response depends only on the climate sensitivity. In the former region the spectral power is proportional to f -2 , where f is the frequency, while in the latter the power is independent of frequency. The range of validity of these results depends on the components of the climate system that are included in the model. In this case these restrict the low-frequency results to time scales less than about 1,000 years. A qualitative extrapolation is presented in an attempt to explain the observed low-frequency power spectra from deep-sea-core δ 18 O time series. The spectral results are also used to estimate the effective heat capacity of the ocean as a function of frequency. At low frequencies, this can range up to 50 times greater than the heat capacity of the mixed layer. Results in the time domain are obtained by solving the model equations numerically
Formation of plasma and gaseous toroidal vortices in air
International Nuclear Information System (INIS)
Yusupaliev, U.; Yusupaliev, P. U.; Shuteev, S. A.
2007-01-01
The mechanism for the formation of high-temperature (plasma) vortices and low-temperature vortex rings produced by ejecting pulsed subsonic plasma/gas jets into air was investigated experimentally. A toroidal vortex forms due to the interaction between a pulsed jet with the flow induced by this jet in the ambient medium. By analyzing the experimental data and conservation laws, an equation is derived that allows one to determine the initial propagation velocity of the vortex as a function of the characteristics of the vortex generator and the ambient medium. The results obtained by solving this equation agree well with the experimental data
Formation of polymeric toroidal-spiral particles.
Sharma, Vishal; Szymusiak, Magdalena; Shen, Hao; Nitsche, Ludwig C; Liu, Ying
2012-01-10
Compared to spherical matrices, particles with well-defined internal structure provide large surface to volume ratio and predictable release kinetics for the encapsulated payloads. We describe self-assembly of polymeric particles, whereby competitive kinetics of viscous sedimentation, diffusion, and cross-linking yield a controllable toroidal-spiral (T-S) structure. Precursor polymeric droplets are splashed through the surface of a less dense, miscible solution, after which viscous forces entrain the surrounding bulk solution into the sedimenting polymer drop to form T-S channels. The intricate structure forms because low interfacial tension between the two miscible solutions is dominated by viscous forces. The biocompatible polymer, poly(ethylene glycol) diacrylate (PEG-DA), is used to demonstrate the solidification of the T-S shapes at various configurational stages by UV-triggered cross-linking. The dimensions of the channels are controlled by Weber number during impact on the surface, and Reynolds number and viscosity ratio during subsequent sedimentation. We anticipate applications of the T-S particle in drug delivery, wherein diffusion through these T-S channels and the polymer matrix would offer parallel release pathways for molecules of different sizes. Polyphosphate, as a model macromolecule, is entrained in T-S particles during their formation. The in vitro release kinetics of polyphosphate from the T-S particles with various channel length and width is reported. In addition, self-assembly of T-S particles occurs in a single step under benign conditions for delicate macromolecules, and appears conducive to scaleup.
Effects of toroidicity on resistive tearing modes
International Nuclear Information System (INIS)
Izzo, R.; Monticello, D.A.; Manickam, J.; Strauss, H.R.; Grimm, R.; McGuire, K.
1983-03-01
A reduced set of resistive MHD equations is solved numerically in three dimensions to study the stability of tokamak plasmas. Toroidal effects are included self-consistently to leading and next order in inverse aspect ratio, epsilon. The equations satisfy an energy integral. In addition, the momentum equation yields the Grad-Shafranov equation correct to all orders in epsilon. Low beta plasma are studied using several different q-profiles. In all cases, the linear growth rates are reduced by finite toroidicity. Excellent agreement with resistive PEST is obtianed. In some cases, toroidal effects lead to complete stabilization of the mode. Nonlinear results show smaller saturated island widths for finite aspect ratio compared to the cylindrical limit. If the current channel is wide enough so as to produce steep gradients towards the outside of the plasma, both the finite aspect ratio cases and cylindrical cases disrupt
PDX toroidal field coils stress analysis
International Nuclear Information System (INIS)
Nikodem, Z.D.; Smith, R.A.
1975-01-01
A method used in the stress analysis of the PDX toroidal field coil is developed. A multilayer coil design of arbitrary dimensions in the shape of either a circle or an oval is considered. The analytical model of the coil and the supporting coil case with connections to the main support structure is analyzed using the finite element technique. The three dimensional magnetic fields and the non-uniform body forces which are a loading condition on a coil due to toroidal and poloidal fields are calculated. The method of analysis permits rapid and economic evaluations of design changes in coil geometry as well as in coil support structures. Some results pertinent to the design evolution and their comparison are discussed. The results of the detailed stress analysis of the final coil design due to toroidal field, poloidal field and temperature loads are presented
Toroidal mode-conversion in the ICRF
International Nuclear Information System (INIS)
Jaun, A.; Hellsten, T.; Chiu, S.C.
1997-08-01
Mode-conversion is studied in the ion-cyclotron range of frequencies (ICRF) taking into account the toroidal geometry relevant for tokamaks. The global wavefields obtained using the gyrokinetic toroidal PENN code illustrate how the fast wave propagates to the neighborhood of the ion-ion hybrid resonance, where it is converted to a slow wave which deposits the wave energy through resonant interactions with the particles. The power deposition profiles obtained are dramatically different from the toroidal resonance absorption, showing that Budden's model is not a good approximation in the torus. Radially and poloidally localized wavefield structures characteristic of slow wave eigenmodes are predicted and could in experiments be driven to large amplitudes so as to interact efficiently with fast particles. (author) 5 figs., 1 tab., 48 refs
Models for large superconducting toroidal magnet systems
International Nuclear Information System (INIS)
Arendt, F.; Brechna, H.; Erb, J.; Komarek, P.; Krauth, H.; Maurer, W.
1976-01-01
Prior to the design of large GJ toroidal magnet systems it is appropriate to procure small scale models, which can simulate their pertinent properties and allow to investigate their relevant phenomena. The important feature of the model is to show under which circumstances the system performance can be extrapolated to large magnets. Based on parameters such as the maximum magnetic field and the current density, the maximum tolerable magneto-mechanical stresses, a simple method of designing model magnets is presented. It is shown how pertinent design parameters are changed when the toroidal dimensions are altered. In addition some conductor cost estimations are given based on reactor power output and wall loading
Guiding Center Equations in Toroidal Equilibria
International Nuclear Information System (INIS)
White, Roscoe; Zakharov, Leonid
2002-01-01
Guiding center equations for particle motion in a general toroidal magnetic equilibrium configuration are derived using magnetic coordinates. Previous derivations made use of Boozer coordinates, in which the poloidal and toroidal angle variables are chosen so that the Jacobian is inversely proportional to the square of the magnetic field. It is shown that the equations for guiding center motion in any equilibrium possessing nested flux surfaces have exactly the same simple form as those derived in this special case. This allows the use of more spatially uniform coordinates instead of the Boozer coordinates, greatly increasing the accuracy of calculations in large beta and strongly shaped equilibria
Current control necessary for toroidal plasma equilibrium
International Nuclear Information System (INIS)
Nagao, S.
1987-01-01
It is shown that a significant amount of dipole current is necessary for the plasma equilibrium of toroidal configurations in general. Through the vector product with the poloidal field, this dipole current force has to balance with the hoop force of plasma pressure itself of the annular shape. The measurement of such a current of dipole type may be interesting for the confirmation of the plasma equilibrium in the toroidal system. Moreover it is certained that there is a new mode of a tokamak operation with such a dipole current component and with smaller vertical field than that based on the classical tokamak theory. (author) [pt
Toroidal Precession as a Geometric Phase
Energy Technology Data Exchange (ETDEWEB)
J.W. Burby and H. Qin
2012-09-26
Toroidal precession is commonly understood as the orbit-averaged toroidal drift of guiding centers in axisymmetric and quasisymmetric configurations. We give a new, more natural description of precession as a geometric phase effect. In particular, we show that the precession angle arises as the holonomy of a guiding center's poloidal trajectory relative to a principal connection. The fact that this description is physically appropriate is borne out with new, manifestly coordinate-independent expressions for the precession angle that apply to all types of orbits in tokamaks and quasisymmetric stellarators alike. We then describe how these expressions may be fruitfully employed in numerical calculations of precession.
On the generation and evolution of internal solitary waves in the southern Red Sea
Guo, Daquan
2015-04-01
Satellite observations recently revealed the existence of trains of internal solitary waves in the southern Red Sea between 16.0°N and 16.5°N, propagating from the centre of the domain toward the continental shelf [Da silva et al., 2012]. Given the relatively weak tidal velocity in this area and their generation in the central of the domain, Da Silva suggested three possible mechanisms behind the generation of the waves, namely Resonance and disintegration of interfacial tides, Generation of interfacial tides by impinging, remotely generated internal tidal beams and for geometrically focused and amplified internal tidal beams. Tide analysis based on tide stations data and barotropic tide model in the Red Sea shows that tide is indeed very weak in the centre part of the Red Sea, but it is relatively strong in the northern and southern parts (reaching up to 66 cm/s). Together with extreme steep slopes along the deep trench, it provides favourable conditions for the generation of internal solitary in the southern Red Sea. To investigate the generation mechanisms and study the evolution of the internal waves in the off-shelf region of the southern Red Sea we have implemented a 2-D, high-resolution and non-hydrostatic configuration of the MIT general circulation model (MITgcm). Our simulations reproduce well that the generation process of the internal solitary waves. Analysis of the model\\'s output suggests that the interaction between the topography and tidal flow with the nonlinear effect is the main mechanism behind the generation of the internal solitary waves. Sensitivity experiments suggest that neither tidal beam nor the resonance effect of the topography is important factor in this process.
A model for the neoclassical toroidal viscosity effect on Edge plasma toroidal rotation
Energy Technology Data Exchange (ETDEWEB)
Miron, I.G. [National Institute for Laser, Plasma and Radiation Physics, Euratom-MEdC Association, Bucharest (Romania)
2013-11-15
A semianalytic expression for the edge plasma angular toroidal rotation frequency that includes the neoclassical toroidal viscosity braking influence is obtained. Based on the model presented in a previous paper [I.G. Miron, Contrib. Plasma Phys. 53, 214 (2013)], the less destabilizing error field spectrum is found in order to minimize the nonlinear effect of the NTV on the toroidal rotation of the edge of the plasma. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
The effect of sheared toroidal rotation on pressure driven magnetic islands in toroidal plasmas
Energy Technology Data Exchange (ETDEWEB)
Hegna, C. C. [Departments of Engineering Physics and Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2016-05-15
The impact of sheared toroidal rotation on the evolution of pressure driven magnetic islands in tokamak plasmas is investigated using a resistive magnetohydrodynamics model augmented by a neoclassical Ohm's law. Particular attention is paid to the asymptotic matching data as the Mercier indices are altered in the presence of sheared flow. Analysis of the nonlinear island Grad-Shafranov equation shows that sheared flows tend to amplify the stabilizing pressure/curvature contribution to pressure driven islands in toroidal tokamaks relative to the island bootstrap current contribution. As such, sheared toroidal rotation tends to reduce saturated magnetic island widths.
The linear stability analysis of MHD models in axisymmetric toroidal geometry
International Nuclear Information System (INIS)
Manickam, J.; Grimm, R.C.; Dewar, R.L.
1981-01-01
A computational model to analyze the linear stability properties of general toroidal systems in the ideal magnetohydrodynamic limits is presented. This model includes an explicit treatment of the asymptotic singular behaviour at rational surfaces. It is verified through applications to internal kink modes. (orig.)
Radial electric field in JET advanced tokamak scenarios with toroidal field ripple
Crombe, K.; Andrew, Y.; Biewer, T. M.; Blanco, E.; de Vries, P. C.; Giroud, C.; Hawkes, N. C.; Meigs, A.; Tala, T.; von Hellermann, M.; Zastrow, K. D.
2009-01-01
A dedicated campaign has been run on JET to study the effect of toroidal field (TF) ripple on plasma performance. Radial electric field measurements from experiments on a series of plasmas with internal transport barriers (ITBs) and different levels of ripple amplitude are presented. They have been
Stress analyses of ITER toroidal field coils under fault conditions
International Nuclear Information System (INIS)
Jong, C.T.J.
1990-02-01
The International Thermonuclear Experimental Reactor (ITER) is intended as an experimental thermonuclear tokamak reactor for testing the basic physics, performance and technologies essential to future fusion reactors. The ITER design will be based on extensive new design work, supported by new physical and technological results, and on the great body of experience built up over several years from previous national and international reactor studies. Conversely, the ITER design process should provide the fusion community with valuable insights into what key areas need further development or clarification as we move forward towards practical fusion power. As part of the design process of the ITER toroidal field coils the mechanical behaviour of the magnetic system under fault conditions has to be analysed in more detail. This paper describes the work carried out to create a detailed finite element model of two toroidal field coils as well as some results of linear elastic analyses with fault conditions. The analyses have been performed with the finite element code ANSYS. (author). 5 refs.; 8 figs.; 2 tabs
Ogawa, Kenji; Inui, Toshio
2007-11-01
Internal monitoring or state estimation of movements is essential for human motor control to compensate for inherent delays and noise in sensorimotor loops. Two types of internal estimation of movements exist: self-generated movements, and externally generated movements. We used functional magnetic resonance imaging to investigate differences in brain activity for internal monitoring of self- versus externally generated movements during visual occlusion. Participants tracked a sinusoidally moving target with a mouse cursor. On some trials, vision of either target (externally generated) or cursor (self-generated) movement was transiently occluded, during which subjects continued tracking by estimating current position of either the invisible target or cursor on screen. Analysis revealed that both occlusion conditions were associated with increased activity in the presupplementary motor area and decreased activity in the right lateral occipital cortex compared to a control condition with no occlusion. Moreover, the right and left posterior parietal cortex (PPC) showed greater activation during occlusion of target and cursor movements, respectively. This study suggests lateralization of the PPC for internal monitoring of internally versus externally generated movements, fully consistent with previously reported clinical findings.
Quench propagation and protection analysis of the ATLAS Toroids
Dudarev, A; Gavrilin, A V; ten Kate, H H J; Baynham, D Elwyn; Courthold, M J D; Lesmond, C
2000-01-01
The ATLAS superconducting magnet system consists of the Barrel Toroid, two End Cap Toroids and the Central Solenoid. However, the Toroids of eight coils each are magnetically separate systems to the Central Solenoid. The Toroids are electrically connected in series and energized by a single power supply. The quench protection system is based on the use of relatively small external dump resistances in combination with quench-heaters activated after a quench event detection to initiate the inte...
New material equations for electromagnetism with toroid polarizations
International Nuclear Information System (INIS)
Dubovik, V.M.; Martsenyuk, M.A.; Saha, B.
1999-09-01
With regard to the toroid contributions, a modified system of equations of electrodynamics moving continuous media has been obtained. Alternative formalisms to introduce the toroid moment contributions in the equations of electromagnetism has been worked out. The two four-potential formalism has been developed. Lorentz transformation laws for the toroid polarizations has been given. Covariant form of equations of electrodynamics of continuous media with toroid polarizations has been written. (author)
Xu, Jiexin; Chen, Zhiwu; Xie, Jieshuo; Cai, Shuqun
2016-03-01
In this paper, the generation and evolution of seaward propagating internal solitary waves (ISWs) detected by satellite image in the northwestern South China Sea (SCS) are investigated by a fully nonlinear, non-hydrostatic, three-dimensional Massachusetts Institute of Technology general circulation model (MITgcm). The three-dimensional (3D) modeled ISWs agree favorably with those by satellite image, indicating that the observed seaward propagating ISWs may be generated by the interaction of barotropic tidal flow with the arc-like continental slope south of Hainan Island. Though the tidal current is basically in east-west direction, different types of internal waves are generated by tidal currents flowing over the slopes with different shaped shorelines. Over the slope where the shoreline is straight, only weak internal tides are generated; over the slope where the shoreline is seaward concave, large-amplitude internal bores are generated, and since the concave isobaths of the arc-like continental slope tend to focus the baroclinic tidal energy which is conveyed to the internal bores, the internal bores can efficiently disintegrate into a train of rank-ordered ISWs during their propagation away from the slope; while over the slope where the shoreline is seaward convex, no distinct internal tides are generated. It is also implied that the internal waves over the slope are generated due to mixed lee wave mechanism. Furthermore, the effects of 3D model, continental slope curvature, stratification, rotation and tidal forcing on the generation of ISWs are discussed, respectively. It is shown that, the amplitude and phase speed of ISWs derived from a two-dimensional (2D) model are smaller than those from the 3D one, and the 3D model has an advantage over 2D one in simulating the ISWs generated by the interaction between tidal currents and 3D curved continental slope; the reduced continental slope curvature hinders the extension of ISW crestline; both weaker stratification
Toroidal groups line bundles, cohomology and quasi-Abelian varieties
Kopfermann, Klaus
2001-01-01
Toroidal groups are the connecting link between torus groups and any complex Lie groups. Many properties of complex Lie groups such as the pseudoconvexity and cohomology are determined by their maximal toroidal subgroups. Quasi-Abelian varieties are meromorphically separable toroidal groups. They are the natural generalisation of the Abelian varieties. Nevertheless, their behavior can be completely different as the wild groups show.
Anisotropic diffusion in a toroidal geometry
International Nuclear Information System (INIS)
Fischer, Paul F
2005-01-01
As part of the Department of Energy's applications oriented SciDAC project, three model problems have been proposed by the Center for Extended Magnetohydrodynamics Modeling to test the potential of numerical algorithms for challenging magnetohydrodynamics (MHD) problems that are required for future fusion development. The first of these, anisotropic diffusion in a toroidal geometry, is considered in this note
Trapped ion mode in toroidally rotating plasmas
International Nuclear Information System (INIS)
Artun, M.; Tang, W.M.; Rewoldt, G.
1995-04-01
The influence of radially sheared toroidal flows on the Trapped Ion Mode (TIM) is investigated using a two-dimensional eigenmode code. These radially extended toroidal microinstabilities could significantly influence the interpretation of confinement scaling trends and associated fluctuation properties observed in recent tokamak experiments. In the present analysis, the electrostatic drift kinetic equation is obtained from the general nonlinear gyrokinetic equation in rotating plasmas. In the long perpendicular wavelength limit k τ ρ bi much-lt 1, where ρ bi is the average trapped-ion banana width, the resulting eigenmode equation becomes a coupled system of second order differential equations nmo for the poloidal harmonics. These equations are solved using finite element methods. Numerical results from the analysis of low and medium toroidal mode number instabilities are presented using representative TFTR L-mode input parameters. To illustrate the effects of mode coupling, a case is presented where the poloidal mode coupling is suppressed. The influence of toroidal rotation on a TFTR L-mode shot is also analyzed by including a beam species with considerable larger temperature. A discussion of the numerical results is presented
Design of the TPX outboard toroidal limiters
International Nuclear Information System (INIS)
Schaubel, K.M.; Anderson, P.M.; Baxi, C.B.
1995-01-01
The Tokamak Physics Experiment outboard limiter system incorporates the passive stabilizer plates, the ripple armor, the toroidal break and the support structures. These components are designed to withstand substantial steady state heat loads and high mechanical forces caused by plasma disruptions. The design of these components has been developed to deal with the challenging thermal, structural and remote handling requirements
Escape of magnetic toroids from the Sun
International Nuclear Information System (INIS)
Bieber, John W.; Rust, David M.
1996-01-01
Analysis of heliospheric magnetic fields at 1 AU shows that 10 24 Mx of net toroidal flux escapes from the Sun per solar cycle. This rate is compared with the apparent rate of flux emergence at the solar surface, and it is concluded that escaping toroids will remove at least 20% of the emerging flux, and may remove as much as 100% of emerging flux if multiple eruptions occur on the toroids. The data imply that flux escapes the Sun with an efficiency far exceeding Parker's upper limit estimate of 3%. Toroidal flux escape is almost certainly the source of the observed overwinding of the interplanetary magnetic field spiral. Two mechanisms to facilitate net flux escape are discussed: helicity charging to push open the fields and flux transport with reconnection to close them off. We estimate the Sun will shed ∼2x10 45 Mx 2 of magnetic helicity per solar cycle, leading to a mean helicity density of 100 Mx 2 cm -3 at 1 AU, which agrees well with observations
Celebration for the ATLAS Barrel Toroid magnet
2007-01-01
Representatives from Funding Agencies and Barrel Toroid Magnet Laboratories during the ceremony. From left to right: Jean Zinn-Justin (Head of DAPNIA/CEA/Saclay), CERN Director-General Robert Aymar, and Roberto Petronzio (President INFN).Allan Clark (DPNC University Geneva) and Enrique Fernandez (IFAE Barcelona) were among the guests visiting the ATLAS cavern. The barrel toroid is visible in the background. A celebration took place at Point 1 on 13 December to toast the recent powering-up of the ATLAS barrel toroid magnet to full field (Bulletin No. 47-48/06). About 70 guests were invited to attend, mainly composed of representatives from funding partners and key members of the laboratory management teams of the barrel toroid magnet, representing CEA France, INFN Italy, BMBF Germany, Spain, Sweden, Switzerland, Russia, JINR Dubna and CERN. An introductory speech by ATLAS spokesperson Peter Jenni the scene for evening. This was followed by the ATLAS magnet system project leader Herman Ten Kate's account of the...
Curvature driven instabilities in toroidal plasmas
International Nuclear Information System (INIS)
Andersson, P.
1986-11-01
The electromagnetic ballooning mode, the curvature driven trapped electron mode and the toroidally induced ion temperature gradient mode have been studies. Eigenvalue equations have been derived and solved both numerically and analytically. For electromagnetic ballooning modes the effects of convective damping, finite Larmor radius, higher order curvature terms, and temperature gradients have been investigated. A fully toroidal fluid ion model has been developed. It is shown that a necessary and sufficient condition for an instability below the MHD limit is the presence of an ion temperature gradient. Analytical dispersion relations giving results in good agreement with numerical solutions are also presented. The curvature driven trapped electron modes are found to be unstable for virtually all parameters with growth rates of the order of the diamagnetic drift frequency. Studies have been made, using both a gyrokinetic ion description and the fully toroidal ion model. Both analytical and numerical results are presented and are found to be in good agreement. The toroidally induced ion temperature gradients modes are found to have a behavior similar to that of the curvature driven trapped electron modes and can in the electrostatic limit be described by a simple quadratic dispersion equation. (author)
Discussion of discrete D shape toroidal coil
International Nuclear Information System (INIS)
Kaiho, Katsuyuki; Ohara, Takeshi; Agatsuma, Ko; Onishi, Toshitada
1988-01-01
A novel design for a toroidal coil, called the D shape coil, was reported by J. File. The coil conductors are in pure tension and then subject to no bending moment. This leads to a smaller number of emf supports in a simpler configuration than that with the conventional toroidal coil of circular cross-section. The contours of the D shape are given as solutions of a differential equation. This equation includes the function of the magnetic field distribution in the conductor region which is inversely proportional to the winding radius. It is therefore important to use the exact magnetic field distribution. However the magnetic field distribution becomes complicated when the D shape toroidal coil is comprised of discrete coils and also depends on the D shape configuration. A theory and a computer program for designing the practical pure-tension toroidal coil are developed. Using this computer code, D shape conductors are calculated for various numbers of discrete coils and the results are compared. Electromagnetic forces in the coils are also calculated. It is shown that the hoop stress in the conductors depends only on the total ampere-turns of the coil when the contours of the D shape are similar. (author)
Neoclassical poloidal and toroidal rotation in tokamaks
International Nuclear Information System (INIS)
Kim, Y.B.; Diamond, P.H.; Groebner, R.J.
1991-01-01
Explicit expressions for the neoclassical poloidal and toroidal rotation speeds of primary ion and impurity species are derived via the Hirshman and Sigmar moment approach. The rotation speeds of the primary ion can be significantly different from those of impurities in various interesting cases. The rapid increase of impurity poloidal rotation in the edge region of H-mode discharges in tokamaks can be explained by a rapid steepening of the primary ion pressure gradient. Depending on ion collisionality, the poloidal rotation speed of the primary ions at the edge can be quite small and the flow direction may be opposite to that of the impurities. This may cast considerable doubts on current L to H bifurcation models based on primary ion poloidal rotation only. Also, the difference between the toroidal rotation velocities of primary ions and impurities is not negligible in various cases. In Ohmic plasmas, the parallel electric field induces a large impurity toroidal rotation close to the magnetic axis, which seems to agree with experimental observations. In the ion banana and plateau regime, there can be non-negligible disparities between primary ion and impurity toroidal rotation velocities due to the ion density and temperature gradients. Detailed analytic expressions for the primary ion and impurity rotation speeds are presented, and the methodology for generalization to the case of several impurity species is also presented for future numerical evaluation
ATLAS Barrel Toroid magnet reached nominal field
2006-01-01
Â OnÂ 9 November the barrel toroid magnet reached its nominal field of 4 teslas, with an electrical current of 21 000 amperes (21 kA) passing through the eight superconducting coils as shown on this graph
ATLAS: Full power for the toroid magnet
2006-01-01
The 9th of November was a memorable day for ATLAS. Just before midnight, the gigantic Barrel toroid magnet reached its nominal field of 4 teslas in the coil windings, with an electrical current of 21000 amperes (21 kA) passing through the eight superconducting coils (as seen on the graph). This achievement was obtained after several weeks of commissioning. The ATLAS Barrel Toroid was first cooled down for about six weeks in July-August to -269Â°C (4.8 K) and then powered up step-by-step in successive test sessions to 21 kA. This is 0.5 kA above the current required to produce the nominal magnetic field. Afterwards, the current was safely switched off and the stored magnetic energy of 1.1 gigajoules was dissipated in the cold mass, raising its temperature to a safe -218Â°C (55 K). 'We can now say that the ATLAS Barrel Toroid is ready for physics,' said Herman ten Kate, project leader for the ATLAS magnet system. The ATLAS barrel toroid magnet is the result of a close collaboration between the magnet la...
Characterisation of the Interaction between Toroidal Vortex Structures and Flame Front Propagation
International Nuclear Information System (INIS)
Long, E J; Hargrave, G K; Jarvis, S; Justham, T; Halliwell, N
2006-01-01
Experimental laser diagnostic data is presented for flame characterisation during interactions with toroidal vortices generated in the wake of an annular obstacle. A novel twin section combustion chamber has been utilised to allow the controlled formation of stable eddy structures into which a flame front can propagate. High speed laser sheet visualisation was employed to record the flow field and flame front temporal development and high-speed digital particle image velocimetry was used to quantify the velocity field of the unburnt mixture ahead of the flame front. Results provide characterisation of the toroidal vortex/flame front interaction for a range of vortex scales of and recirculation strengths
Characterisation of the Interaction between Toroidal Vortex Structures and Flame Front Propagation
Energy Technology Data Exchange (ETDEWEB)
Long, E J; Hargrave, G K; Jarvis, S; Justham, T; Halliwell, N [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU (United Kingdom)
2006-07-15
Experimental laser diagnostic data is presented for flame characterisation during interactions with toroidal vortices generated in the wake of an annular obstacle. A novel twin section combustion chamber has been utilised to allow the controlled formation of stable eddy structures into which a flame front can propagate. High speed laser sheet visualisation was employed to record the flow field and flame front temporal development and high-speed digital particle image velocimetry was used to quantify the velocity field of the unburnt mixture ahead of the flame front. Results provide characterisation of the toroidal vortex/flame front interaction for a range of vortex scales of and recirculation strengths.
Characterisation of the Interaction between Toroidal Vortex Structures and Flame Front Propagation
Long, E. J.; Hargrave, G. K.; Jarvis, S.; Justham, T.; Halliwell, N.
2006-07-01
Experimental laser diagnostic data is presented for flame characterisation during interactions with toroidal vortices generated in the wake of an annular obstacle. A novel twin section combustion chamber has been utilised to allow the controlled formation of stable eddy structures into which a flame front can propagate. High speed laser sheet visualisation was employed to record the flow field and flame front temporal development and high-speed digital particle image velocimetry was used to quantify the velocity field of the unburnt mixture ahead of the flame front. Results provide characterisation of the toroidal vortex/flame front interaction for a range of vortex scales of and recirculation strengths.
Experiments on toroidal inductively coupled alternating-current gas discharges
International Nuclear Information System (INIS)
Lok, J.
1976-01-01
This report is on an experimental study of a toroidal, inductively coupled a.c. gas discharge sustained at pressures roughly between one tenth of a Torr and some tens of Torrs. After breakdown is obtained at low pressure, additional gas is let in. The energy is inductively coupled into the electrodeless discharge by means of an iron core transformer of which the toroidal plasma column is the secondary winding. The power dissipated in the plasma is between 80 and 260 kW and is delivered by a motor-generator system at a frequency of 8 kHz for times up to 2 seconds. A toroidal magnetic field of 0.5 T maximum can be supplied in a short pulse. Five different gases (hydrogen, deuterium, helium, argon, and nitrogen) are used. The pressure range in which the discharges are sustained is specified, and the dynamic current-voltage characteristics are given for different pressures. Some typical streak pictures with simultaneously obtained recordings of the time behaviour of the discharge current and of the loop voltage are presented for the initial phase - at low pressure - of the discharge. The shape and the position of fully developed discharges at various pressures are discussed on the basis of photographic observations. The temperature of hydrogen plasmas is derived both from the electrical conductivity and from the emission of line radiation. The values of the temperature obtained in these ways differ in magnitude and in time behaviour. A possible explanation of the discrepancy can be obtained in terms of expansion and contraction of electron density and temperature profiles during a period of the discharge current, if it is taken into account that the main part of the light emission always originates from the outer colder regions of the plasma. In a somewhat different pressure regime, this picture is confirmed by microwave measurements
Relativistic stars with purely toroidal magnetic fields
International Nuclear Information System (INIS)
Kiuchi, Kenta; Yoshida, Shijun
2008-01-01
We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The basic equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal magnetic fields are derived for the first time. To solve these basic equations numerically, we extend the Cook-Shapiro-Teukolsky scheme for calculating relativistic rotating stars containing no magnetic field to incorporate the effects of the purely toroidal magnetic fields. By using the numerical scheme, we then calculate a large number of the equilibrium configurations for a particular distribution of the magnetic field in order to explore the equilibrium properties. We also construct the equilibrium sequences of the constant baryon mass and/or the constant magnetic flux, which model the evolution of an isolated neutron star as it loses angular momentum via the gravitational waves. Important properties of the equilibrium configurations of the magnetized stars obtained in this study are summarized as follows: (1) For the nonrotating stars, the matter distribution of the stars is prolately distorted due to the toroidal magnetic fields. (2) For the rapidly rotating stars, the shape of the stellar surface becomes oblate because of the centrifugal force. But, the matter distribution deep inside the star is sufficiently prolate for the mean matter distribution of the star to be prolate. (3) The stronger toroidal magnetic fields lead to the mass shedding of the stars at the lower angular velocity. (4) For some equilibrium sequences of the constant baryon mass and magnetic flux, the stars can spin up as they lose angular momentum.
Directory of Open Access Journals (Sweden)
R. Maugé
2008-03-01
Full Text Available A set of evolution equations is derived for the modal coefficients in a weakly nonlinear nonhydrostatic internal-tide generation problem. The equations allow for the presence of large-amplitude topography, e.g. a continental slope, which is formally assumed to have a length scale much larger than that of the internal tide. However, comparison with results from more sophisticated numerical models show that this restriction can in practice be relaxed. It is shown that a topographically induced coupling between modes occurs that is distinct from nonlinear coupling. Nonlinear effects include the generation of higher harmonics by reflection from boundaries, i.e. steeper tidal beams at frequencies that are multiples of the basic tidal frequency. With a seasonal thermocline included, the model is capable of reproducing the phenomenon of local generation of internal solitary waves by a tidal beam impinging on the seasonal thermocline.
Development of compact toroids injector for direct plasma controls
Energy Technology Data Exchange (ETDEWEB)
Azuma, K. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Oda, Y. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Onozuka, M. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Uyama, T. [Himeji Inst. of Tech. (Japan); Nagata, M. [Himeji Inst. of Tech. (Japan); Fukumoto, N. [Himeji Inst. of Tech. (Japan)
1995-12-31
The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 10{sup 21}m{sup -3}. (orig.).
Development of compact toroids injector for direct plasma controls
International Nuclear Information System (INIS)
Azuma, K.; Oda, Y.; Onozuka, M.; Uyama, T.; Nagata, M.; Fukumoto, N.
1995-01-01
The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 10 21 m -3 . (orig.)
Advanced transport modeling of toroidal plasmas with transport barriers
International Nuclear Information System (INIS)
Fukuyama, A.; Murakami, S.; Honda, M.; Izumi, Y.; Yagi, M.; Nakajima, N.; Nakamura, Y.; Ozeki, T.
2005-01-01
Transport modeling of toroidal plasmas is one of the most important issue to predict time evolution of burning plasmas and to develop control schemes in reactor plasmas. In order to describe the plasma rotation and rapid transition self-consistently, we have developed an advanced scheme of transport modeling based on dynamical transport equation and applied it to the analysis of transport barrier formation. First we propose a new transport model and examine its behavior by the use of conventional diffusive transport equation. This model includes the electrostatic toroidal ITG mode and the electromagnetic ballooning mode and successfully describes the formation of internal transport barriers. Then the dynamical transport equation is introduced to describe the plasma rotation and the radial electric field self-consistently. The formation of edge transport barriers is systematically studied and compared with experimental observations. The possibility of kinetic transport modeling in velocity space is also examined. Finally the modular structure of integrated modeling code for tokamaks and helical systems is discussed. (author)
Brain mechanisms associated with internally directed attention and self-generated thought.
Benedek, Mathias; Jauk, Emanuel; Beaty, Roger E; Fink, Andreas; Koschutnig, Karl; Neubauer, Aljoscha C
2016-03-10
Internal cognition like imagination and prospection require sustained internally directed attention and involve self-generated thought. This fMRI study aimed to disentangle the brain mechanisms associated with attention-specific and task-specific processes during internally directed cognition. The direction of attention was manipulated by either keeping a relevant stimulus visible throughout the task, or by masking it, so that the task had to be performed "in the mind's eye". The level of self-directed thought was additionally varied between a convergent and a divergent thinking task. Internally directed attention was associated with increased activation in the right anterior inferior parietal lobe (aIPL), bilateral lingual gyrus and the cuneus, as well as with extended deactivations of superior parietal and occipital regions representing parts of the dorsal attention network. The right aIPL further showed increased connectivity with occipital regions suggesting an active top-down mechanism for shielding ongoing internal processes from potentially distracting sensory stimulation in terms of perceptual decoupling. Activation of the default network was not related to internally directed attention per se, but rather to a higher level of self-generated thought. The findings hence shed further light on the roles of inferior and superior parietal cortex for internally directed cognition.
Toroidal deuteron accelerator for Mo-98 neutron activation
International Nuclear Information System (INIS)
Araujo, Wagner L.; Campos, Tarcisio P.R. Universidade Federal de Minas Gerais
2017-01-01
The radionuclide Tc- 99m is the most useful radioisotope in nuclear medicine. It can be produced by the Mo-99 beta minus decay. Mo-99 has often been produced in a high- flux nuclear reactor through radioactive neutron capture reactions on Mo-98. The present paper provides a preliminary design of a toroidal transmutation system (TTS) based on a toroidal compact deuteron accelerator, which can provide the Mo-98 transmutation into Mo-99. This system is essentially composed of a multi-aperture plasma electrode and a target, submitted to 180 kV, where a positive deuteron beam is accelerated toward a titanium-target loaded with deuterium in which nuclear d-d fusion reactions are induced. The Particle Studio package of the Computer Simulation Technology (CST) software was applied to design, simulate and optimize the deuteron beam on the target. MCNP code provided to neutronic analysis. Based on electromagnetic and neutronic simulations, the neutron yield and reaction rates were estimated. The simulated data allowed appraising the Mo-99 activity. A TTS, in a specific configuration, could produce a total deuterium current of 1.6 A at the target and a neutron yield of 10 13 n.s -1 . In a arrangement of 30 column samples, TTS provides 230 mCi s -1 Mo 99 in each column, which represents 80% of Tc-99m in secular equilibrium. As conclusion, the system holds potential for generating Mo-99 and Tc-99m in a suitable activity in secular equilibrium. (author)
Toroidal magnetic confinement of non-neutral plasmas
International Nuclear Information System (INIS)
Yoshida, Zensho; Ogawa, Yuichi; Morikawa, Junji; Himura, Haruhiko; Kondo, Shigeo; Nakashima, Chihiro; Kakuno, Shuichi; Iqbal, Muhamad; Volponi, Francesco; Shibayama, Norihisa; Tahara, Shigeru
1999-01-01
A new method of toroidal non-neutral plasma trap has been developed with applying the chaos-induced radial transport of particles near a magnetic null point. A pure electron plasma is produced by injecting an electron beam. The poloidal gyroradius of an electron at the energy of 1 keV is of order 10 mm, which determines the length scale of the chaotic region. Amongst various applications of toroidal non-neutral plasmas, a possibility of producing very high-β plasma, which is suitable for advanced fusion, has been examined. The self-electric field of a non-neutral plasma can generate a strong shear flow. When the flow velocity is comparable to the Alfven speed (which is smaller than the ion sound speed, if β>1), a high-β equilibrium can be produced in which the plasma pressure is primarily balanced by the dynamic pressure of the flow. This configuration is described by a generalized Bernoulli law
Current disruption in toroidal devices
International Nuclear Information System (INIS)
1979-07-01
Attempts at raising the density or the plasma current in a tokamak above certain critical values generally result in termination of the discharge by a disruption. This sudden end of the plasma current and plasma confinement is accompanied by large induced voltages and currents in the outer structures which, in large tokamaks, can only be handled with considerable effort, and which will probably only be tolerable in reactors as rare accidents. Because of its crucial importance for the construction and operation of tokamaks, this phenomenon and its theoretical interpretation were the subject of a three-day symposium organized by the International Atomic Energy Agency and Max-Planck-Institut fuer Plasmaphysik at Garching from February 14 to 16. (orig./HT)
Toroidal charge exchange recombination spectroscopy on EAST
Energy Technology Data Exchange (ETDEWEB)
Ye, Minyou, E-mail: yemy@ustc.edu.cn [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Li, Yingying [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Yu, Yi [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Yuejiang [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); WCI for Fusion Theory, National Fusion Research Institute, 52 Eoeun-Dong, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Lyu, Bo; Fu, Jia [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Du, Xuewei; Yin, Xianghui; Zhang, Yi; Wang, Qiuping [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wan, Baonian [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China)
2015-10-15
A toroidal charge exchange recombination spectroscopy (CXRS) diagnostic, on the basis of a heating neutral beam injector (NBI), is constructed on EAST tokamak. Simulation of Spectra (SOS) code is used to design and evaluate the diagnostic performance. 30 spatial channels work simultaneously in recent experiment, which covers a radial region from 1.55 m to 2.30 m in the cross section. The CXRS has a radial resolution of 1–3.5 cm from core to edge. The acquisition time is typically 10 ms, limited by the poor photon statistics. The diagnostic can observe not only the normal C{sup 5+} emission line at 529.1 nm but also any interested wavelength in the range of 400–700 nm. In this work, a brief overview on the R&D and the instrument performance for the toroidal CXRS diagnostic is described, together with first results.
Ballooning instabilities in toroidally linked mirror systems
International Nuclear Information System (INIS)
Hastie, R.J.; Watson, C.J.H.
1977-01-01
This paper examines the stability against ballooning modes of plasma equilibria in toroidally linked mirror configurations consisting of a number of quadrupole minimum-B mirrors linked toroidally. On the basis of the Kruskal-Oberman energy principle, a class of displacements is identified which are potentially unstable, and a necessary criterion for stability is derived. The criterion is obtained from the eigenvalues of an ordinary differential equation, which determines the variation of the displacement along a field line. The coefficients in the equation are determined by the configuration, and by inserting various model configurations, estimates are obtained of the maximum value of β consistent with stability. In cases of interest, quite high β-values are obtained. (author)
Substantiation of vibration strength of nuclear reactor and steam generator internals. Main problems
International Nuclear Information System (INIS)
Fyodorov, V.G.; Sinyavasky, V.F.
1977-01-01
The report details the scope and priority of studies necessary for substantiation of vibration strength of steam generator tube bundles and reactor fuel assemblies, and design modifications helping to reduce flow-induced vibration of the internals specified. Steam generator tube bundles are studied on the basis of a standard establishing vibration requirements at various stages of design, manufacture and operation of a steam generator at a nuclear power station. The main vibration characteristics of tubes obtained through model and full-scale tests are compared with calculation results. Results are provided concerning test-stand vibration tests of fuel elements and fuel assemblies. (author)
On the generation and evolution of internal solitary waves in the southern Red Sea
Guo, Daquan; Akylas, T. R.; Zhan, Peng; Kartadikaria, Aditya R.; Hoteit, Ibrahim
2016-01-01
Satellite observations recently revealed trains of internal solitary waves (ISWs) in the off-shelf region between 16.0 degrees N and 16.5 degrees N in the southern Red Sea. The generation mechanism of these waves is not entirely clear, though
METHODS TO DEVELOP A TOROIDAL SURFACE
Directory of Open Access Journals (Sweden)
DANAILA Ligia
2017-05-01
Full Text Available The paper work presents two practical methods to draw the development of a surface unable to be developed applying classical methods of Descriptive Geometry, the toroidal surface, frequently met in technical practice. The described methods are approximate ones; the development is obtained with the help of points. The accuracy of the methods is given by the number of points used when drawing. As for any other approximate method, when practically manufactured the development may need to be adjusted on site.
Unstable universal drift eigenmodes in toroidal plasmas
International Nuclear Information System (INIS)
Cheng, C.Z.; Chen, L.
1980-01-01
The eigenmode equation describing ballooning collisionless drift instabilities is analyzed both analytically and numerically. A new branch of eigenmodes, which corresponds to quasi-bound states due to toroidal coupling effects such as ion delB drifts, is shown to be destabilized by electron Landau damping for typical tokamak parameters. This branch cannot be understood by the strong coupling approximation. However, the slab-like (Pearlstein--Berk-type) branch is found to remain stable and experience enhanced shear damping
Stellarator approach to toroidal plasma confinement
International Nuclear Information System (INIS)
Johnson, J.L.
1981-12-01
An overview is presented of the development and current status of the stellarator approach to controlled thermonuclear confinement. Recent experimental, theoretical, and systems developments have made this concept a viable option for the evolution of the toroidal confinement program. Some experimental study of specific problems associated with departure from two-dimensional symmetry must be undertaken before the full advantages and opportunities of steady-state, net-current-free operation can be realized
Mirror theory applied to toroidal systems
International Nuclear Information System (INIS)
Cohen, R.H.
1987-01-01
Central features of a mirror plasma are strong departures from Maxwellian distribution functions, ambipolar potentials and densities which vary along a field line, and losses, and the mirror field itself. To examine these features, mirror theorists have developed analytical and numerical techniques to solve the Fokker-Planck equation, evaluate the potentials consistent with the resulting distribution functions, and assess the microstability of these distributions. Various combinations of mirror-plasma fetures are present and important in toroidal plasmas as well, particularly in the edge region and in plasmas with strong r.f. heating. In this paper we survey problems in toroidal plasmas where mirror theory and computational techniques are applicable, and discuss in more detail three specific examples: calculation of the toroidal generalization of the Spitzer-Haerm distribution function (from which trapped-particle effects on current drive can be calculated), evaluation of the nonuniform potential and density set up by pulsed electron-cyclotron heating, and calculation of steady-state distribution functions in the presence of strong r.f. heating and collisions. 37 refs., 3 figs
Mirror theory applied to toroidal systems
International Nuclear Information System (INIS)
Cohen, R.H.
1987-01-01
Central features of a mirror plasma are strong departures from Maxwellian distribution functions, ambipolar potentials and densities which vary along a field line, end losses, and the mirror field itself. To examine these features, mirror theorists have developed analytical and numerical techniques to solve the Fokker-Planck equation, evaluate the potentials consistent with the resulting distribution functions, and assess the microstability of these distributions. Various combinations of mirror-plasma features are present and important in toroidal plasmas as well, particularly in the edge region and in plasmas with strong rf heating. In this paper we survey problems in toroidal plasmas where mirror theory and computational techniques are applicable, and discuss in more detail three specific examples: calculation of the toroidal generalization of the Spitzer-Haerm distribution function (from which trapped-particle effects on current drive can be calculated), evaluation of the nonuniform potential and density set up by pulsed electron-cyclotron heating, and calculation of steady-state distribution functions in the presence of strong rf heating and collisions. 37 refs
Superconducting magnets for toroidal fusion reactors
International Nuclear Information System (INIS)
Haubenreich, P.N.
1980-01-01
Fusion reactors will soon be employing superconducting magnets to confine plasma in which deuterium and tritium (D-T) are fused to produce usable energy. At present there is one small confinement experiment with superconducting toroidal field (TF) coils: Tokamak 7 (T-7), in the USSR, which operates at 4 T. By 1983, six different 2.5 x 3.5-m D-shaped coils from six manufacturers in four countries will be assembled in a toroidal array in the Large Coil Test Facility (LCTF) at Oak Ridge National Laboratory (ORNL) for testing at fields up to 8 T. Soon afterwards ELMO Bumpy Torus (EBT-P) will begin operation at Oak Ridge with superconducting TF coils. At the same time there will be tokamaks with superconducting TF coils 2 to 3 m in diameter in the USSR and France. Toroidal field strength in these machines will range from 6 to 9 T. NbTi and Nb 3 Sn, bath cooling and forced flow, cryostable and metastable - various designs are being tried in this period when this new application of superconductivity is growing and maturing
Computer-generated vibratory signatures for EDF PWR reactor vessel internals
International Nuclear Information System (INIS)
Trenty, A.; Lefevre, F.; Garreau, D.
1992-07-01
This paper presents a device for generation of characteristic signatures for normal or faulty vibrations on EDF PWR internal structures. The objective is to test the efficiency of methods for diagnosing faults in these structures. With this device, it is possible to build an entire PSD in several phases: choice of a general basic shape, localized addition of several kinds of background noise, generation of peaks of variable shapes, adjustment of local or global amplifications... It also offers the possibility of distorting real PSDs acquired from the reactor: shifting frequency or modifying peak shape, eliminating or adding existing shapes or shapes to be created, smoothing curves... One example is given of simulated loss of function in a hold-down spring on a computer-generated PSD of ex-core neutron noise. The device is now being used to test the potential of neural networks in recognizing faults on internal structures
Dry out of a fluidized particle bed with internal heat generation
International Nuclear Information System (INIS)
Keowen, R.S.; Catton, I.
1975-03-01
An apparatus was designed to adequately simulate the characteristics of a particle bed formed by nuclear reactor fuel after the reactor has been operable for some length of time at high power. This was accomplished by using a 10 KW, 453 Kc induction heater, coupled through a multi-turn work coil to particle beds of cast steel shot and lead shot in water. The temperature response and dryout condition was determined for various bed levels, particle diameters, and heat fluxes. Analysis of the data retrieved from the bed was used to generate a family of curves to predict the necessary conditions for dryout to occur within a fluidized particle bed with internal heat generation. The results presented here, with internal heat generation, show that previous results with bottom heating and volume heating are conservative. (U.S.)
Heat transfer of liquid-metal magnetohydrodynamic flow with internal heat generation
International Nuclear Information System (INIS)
Kumamaru, Hiroshige; Kurita, Kazuhisa; Kodama, Satoshi
2000-01-01
Numerical calculations on heat transfer of a magnetohydrodynamic (MHD) flow with internal heat generation in a rectangular channel have been performed for the cases of very-large Hartmann numbers, finite wall conductivities and small aspect ratio (i.e. small length ratios of the channel side perpendicular to the applied magnetic field and the side parallel to the field), simulating typical conditions for a fusion-reactor blanket. The Nusselt numbers of the MHD flow in rectangular channels with aspect ratios of 1/10 to 1/40 for Hartmann numbers of ∼5 x 10 5 become ∼10 times higher than those for the corresponding flow under no magnetic field. The Nusselt number becomes higher as the internal heat generation rate increases as far as the heat generation rates in a fusion reactor blanket are considered. (author)
EMPACT: Electrons Muons Partons with Air Core Toroids
International Nuclear Information System (INIS)
Marx, M.D.
1990-01-01
The EMPACT experiment utilizes a broad approach to maximize its discovery potential for new phenomena accessible at the SSC. The high resolution detector has a balances emphasis on, and large acceptance for, electrons, muons, jets, and noninteracting particles, and is capable of utilizing the ultimate luminosity of the SSC. The detector emphasizes excellent calorimetry augmented by TRD tracking, and employs an innovative system of superconducting air core toroids for muon measurements. Significant engineering effort has established the feasibility of a baseline detector concept and has addressed the related issues of support facilities, assembly, and detector integration. The design has been tested against the challenges of predicted phenomena, with the expectation that this will optimize the capacity for observing the unexpected. EMPACT's international collaboration has unprecedented support from major aerospace industries who are providing tools and expertise for project design and integration, which will assure that a detector optimized for performance and cost will be available for the first collisions at the new laboratory
Energy Technology Data Exchange (ETDEWEB)
Proelss, Alexander (ed.) [Trier Univ. (Germany). Inst. of Environmental and Technology Law
2017-08-01
This book compiles the written versions of presentations held at the occasion of an international symposium entitled ''Protecting the Environment for Future Generations - Principles and Actors in International Environmental Law''. The symposium was organized by the Institute of Environmental and Technology Law of Trier University (IUTR) on the basis of a cooperation scheme with the Environmental Law Institute of the Johannes Kepler University Linz, Austria, and took place in Trier on 29-30 October 2015. It brought together a distinguished group of experts from Europe and abroad to address current issues of international and European environmental law. The main objective of the symposium was to take stock of the actors and principles of international and European environmental law, and to analyze how and to what extent these principles have been implemented on the supranational and domestic legal levels.
Matter in the form of toroidal electromagnetic vortices
Hagen, Wilhelm F.
2015-09-01
The creation of charged elementary particles from neutral photons is explained as a conversion process of electromagnetic (EM) energy from linear to circular motion at the speed of light into two localized, toroidal shaped vortices of trapped EM energy that resist change of motion, perceptible as particles with inertia and hence mass. The photon can be represented as a superposition of left and right circular polarized transverse electric fields of opposite polarity originating from a common zero potential axis, the optical axis of the photon. If these components are separated by interaction with a strong field (nucleon) they would curl up into two electromagnetic vortices (EMV) due to longitudinal magnetic field components forming toroids. These vortices are perceptible as opposite charged elementary particles e+/- . These spinning toroids generate extended oscillating fields that interact with stationary field oscillations. The velocity-dependent frequency differences cause beat signals equivalent to matter waves, leading to interference. The extended fields entangled with every particle explain wave particle duality issues. Spin and magnetic moment are the natural outcome of these gyrating particles. As the energy and hence mass of the electron increases with acceleration so does its size shrink proportional to its reduced wavelength. The artificial weak and strong nuclear forces can be easily explained as different manifestations of the intermediate EM forces. The unstable neutron consists of a proton surrounded by a contracted and captured electron. The associated radial EM forces represent the weak nuclear force. The deuteron consists of two axially separated protons held together by a centrally captured electron. The axial EM forces represent the strong nuclear force, providing stability for "neutrons" only within nucleons. The same principles were applied to determine the geometries of force-balanced nuclei. The alpha-particle emerges as a very compact
Directory of Open Access Journals (Sweden)
Hyein eCho
2014-12-01
Full Text Available The conscious field includes not only representations about external stimuli (e.g., percepts, but also conscious contents associated with internal states, such as action-related intentions (e.g., urges. Although understudied, the latter may provide unique insights into the nature of consciousness. To illuminate these phenomena, in a new experimental paradigm (Reflexive Imagery Task [RIT], participants were instructed to not subvocalize the names of visually-presented objects. Each object was presented for 10 s on a screen. Participants indicated whenever they involuntarily subvocalized the object name. Research has revealed that it is difficult to suppress such subvocalizations, which occur on over 80% of the trials. Can the effect survive if one intentionally generates a competing (internally-generated conscious content? If so, this would suggest that intentional and unintentional contents can co-exist simultaneously in consciousness in interesting ways. To investigate this possibility, in one condition, participants were instructed to reiteratively subvocalize a speech sound (da, da, da throughout the trial. This internally generated content is self-generated and intentional. Involuntary subvocalizations of object names still arose on over 80% of the trials. One could hypothesize that subvocalizations occurred because of the pauses between the intended speech sounds, but this is inconsistent with the observation that comparable results arose even when participants subvocalized a continuous, unbroken hum (daaa…. throughout the trial. Regarding inter-content interactions, the continuous hum and object name seem to co-exist simultaneously in consciousness. This intriguing datum requires further investigation. We discuss the implications of this new paradigm for the study of internally-generated conscious contents.
TIBER-II TF [toroidal-field] winding pack design
International Nuclear Information System (INIS)
Kerns, J.A.; Miller, J.R.; Slack, D.S.; Summers, L.T.
1987-01-01
The superconducting, toroidal-field (TF) coils in the Tokamak Ignition/Burn Engineering Reactor (TIBER II) are designed with cable-in-conduit conductor (CICC) using Nb 3 Sn composite strands. To design the CICC winding pack, we used an optimization technique that maximizes the conductor stability without violating the constraints imposed by the structure, electrical insulation, quench protection, and fabrication technique. Detailed helium-properties codes calculate the heat removal along a flow path, and detailed field calculations determine the temperature, current, and stability margins. The conductor sheath is designed as distributed structure to partially support the combined in-plane and out-of-plane loads generated within the winding pack. Pancakes of the coil are wound, reacted, and insulated before being potted in the case. This design is aggressive but fully consistent with good engineering practice. 5 refs., 4 figs., 2 tabs
Roles of electric field on toroidal magnetic confinement
International Nuclear Information System (INIS)
Itoh, Kimitaka; Itoh, Sanae; Sanuki, Heiji; Fukuyama, Atsushi.
1992-11-01
Theoretical research on the influence of the electric field on the toroidal magnetic confinement is surveyed. The static electric field is first described. Physics pictures on the generation of the radial electric field and the influence on the confinement are shown. Neoclassical effects as well as the nonclassical processes are discussed. Emphasis is made on the connection with the improved confinement. Convective cell, i.e. the nonuniform potential on the magnetic surface is also discussed. The roles of the fluctuating electric field are then reviewed. The progress in the recent theories on the anomalous transport is addressed. Through these surveys, the impact of the experiments using the heavy ion beam probes on the modern plasma physics is illustrated. (author) 66 refs
International Nuclear Information System (INIS)
Rosikhin, Ahmad; Winata, Toto
2016-01-01
Internal transmission profile in charges carrier generation layer of graphene/Si based solar cell has been explored theoretically. Photovoltaic device was constructed from graphene/Si heterojunction forming a multilayer stuck with Si as generation layer. The graphene/Si sheet was layered on ITO/glass wafer then coated by Al forming Ohmic contact with Si. Photon incident propagate from glass substrate to metal electrode and assumed that there is no transmission in Al layer. The wavelength range spectra used in this calculation was 200 – 1000 nm. It found that transmission intensity in the generation layer show non-linear behavior and partitioned by few areas which related with excitation process. According to this information, it may to optimize the photons absorption to create more excitation process by inserting appropriate material to enhance optical properties in certain wavelength spectra because of the exciton generation is strongly influenced by photon absorption.
Proceedings of the third international steam generator and heat exchanger conference
International Nuclear Information System (INIS)
1998-01-01
The Third International Steam Generator and Heat Exchanger conference had the objective to present the state of knowledge of steam generator performance and life management, and also heat exchanger technology. As this conference followed on from the previous conferences held in Toronto in 1990 and 1994, the emphasis was on recent developments, particularly those of the last 4 years. The conference provided an opportunity to operators, designers and researchers in the field of steam generation associated with electricity generation by nuclear energy to present their findings and exchange ideas. The conference endeavoured to do this over the widest possible range of subject areas, including: general operating experience, life management and fitness for service strategies, maintenance and inspection, thermalhydraulics, vibration, fretting and fatigue, materials, chemistry and corrosion and the regulatory issues
Proceedings of the third international steam generator and heat exchanger conference
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-07-01
The Third International Steam Generator and Heat Exchanger conference had the objective to present the state of knowledge of steam generator performance and life management, and also heat exchanger technology. As this conference followed on from the previous conferences held in Toronto in 1990 and 1994, the emphasis was on recent developments, particularly those of the last 4 years. The conference provided an opportunity to operators, designers and researchers in the field of steam generation associated with electricity generation by nuclear energy to present their findings and exchange ideas. The conference endeavoured to do this over the widest possible range of subject areas,including: general operating experience, life management and fitness for service strategies, maintenance and inspection, thermalhydraulics, vibration, fretting and fatigue, materials, chemistry and corrosion and the regulatory issues.
Internal stress distribution for generating closure domains in laser-irradiated Fe–3%Si(110) steels
International Nuclear Information System (INIS)
Iwata, Keiji; Imafuku, Muneyuki; Orihara, Hideto; Sakai, Yusuke; Ohya, Shin-Ichi; Suzuki, Tamaki; Shobu, Takahisa; Akita, Koichi; Ishiyama, Kazushi
2015-01-01
Internal stress distribution for generating closure domains occurring in laser-irradiated Fe–3%Si(110) steels was investigated using high-energy X-ray analysis and domain theory based on the variational principle. The measured triaxial stresses inside the specimen were compressive and the stress in the rolling direction became more dominant than stresses in the other directions. The calculations based on the variational principle of magnetic energy for closure domains showed that the measured triaxial stresses made the closure domains more stable than the basic domain without closure domains. The experimental and calculation results reveal that the laser-introduced internal stresses result in the occurrence of the closure domains
About the Toroidal Magnetic Field of a Tokamak Burning Plasma Experiment with Superconducting Coils
International Nuclear Information System (INIS)
Mazzucato, E.
2002-01-01
In tokamaks, the strong dependence on the toroidal magnetic field of both plasma pressure and energy confinement is what makes possible the construction of small and relatively inexpensive burning plasma experiments using high-field resistive coils. On the other hand, the toroidal magnetic field of tokamaks using superconducting coils is limited by the critical field of superconductivity. In this article, we examine the relative merit of raising the magnetic field of a tokamak plasma by increasing its aspect ratio at a constant value of the peak field in the toroidal magnet. Taking ITER-FEAT as an example, we find that it is possible to reach thermonuclear ignition using an aspect ratio of approximately 4.5 and a toroidal magnetic field of 7.3 T. Under these conditions, fusion power density and neutron wall loading are the same as in ITER [International Thermonuclear Experimental Reactor], but the normalized plasma beta is substantially smaller. Furthermore, such a tokamak would be able to reach an energy gain of approximately 15 even with the deterioration in plasma confinement that is known to occur near the density limit where ITER is forced to operate
International Nuclear Information System (INIS)
Narita, Emi; Fukuda, Takeshi; Honda, Mitsuru; Hayashi, Nobuhiko; Urano, Hajime; Ide, Shunsuke
2015-01-01
Tokamak plasmas with an internal transport barrier (ITB) are capable of maintaining improved confinement performance. The ITBs formed in plasmas with the weak magnetic shear and the weak radial electric field shear are often observed to be modest. In these ITB plasmas, it has been found that the electron temperature ITB is steeper when toroidal rotation is in a co-direction with respect to the plasma current than when toroidal rotation is in a counter-direction. To clarify the relationship between the direction of toroidal rotation and heat transport in the ITB region, we examine dominant instabilities using the flux-tube gyrokinetic code GS2. The linear calculations show a difference in the real frequencies; the counter-rotation case has a more trapped electron mode than the co-rotation case. In addition, the nonlinear calculations show that with this difference, the ratio of the electron heat diffusivity χ_e to the ion's χ_i is higher for the counter-rotation case than for the co-rotation case. The difference in χ_e /χ_i agrees with the experiment. We also find that the effect of the difference in the flow shear between the two cases due to the toroidal rotation direction on the linear growth rate is not significant. (author)
Application of plasma focus device to compression of toroidal plasma
International Nuclear Information System (INIS)
Ikuta, Kazunari
1980-01-01
A new concept of compressing a toroidal plasma using a plasma focus device is considered. Maximum compression ratio of toroidal plasma is determined merely by the initial density ratio of the toroidal plasma to a sheet plasma in a focus device because of the Rayleigh-Taylor instability. An initiation senario of plasma-linear is also proposed with a possible application of this concepts to the creation of a burning plasma in reversed field configurations, i.e., burning plasma vortex. (author)
Jackman, Kasey B; Dolezal, Curtis; Bockting, Walter O
2018-01-01
This study examined internalized transnegativity and psychological distress in two age groups of transgender individuals who identified their gender identity on the feminine spectrum (rather than congruent with their male sex assigned at birth). Due to greater visibility and acceptance of gender diversity in the United States, we hypothesized that internalized transnegativity would be lower in the younger compared with the older group, and that the younger generation would, therefore, report lower levels of psychological distress than the older generation. The study sample consisted of trans-feminine individuals (N = 440) who completed a online survey of the U.S. transgender population and comprised a younger group aged 18-24 years (n = 133) and an older group aged 40 years and older (n = 307). Internalized transnegativity was assessed using the Transgender Identity Survey, and psychological distress was assessed with the Brief Symptom Inventory 18. We used regression and mediation analysis to examine differences between the two groups. Contrary to our expectations, the older group reported significantly lower levels of both internalized transnegativity and psychological distress compared with the younger group. Internalized transnegativity partially mediated the relationship between age group and psychological distress. Despite greater visibility of transgender people and increasing acceptance of gender diversity in the United States, the younger trans-feminine individuals reported more psychological distress than the older transfeminine individuals, which was, in part, related to internalized transnegativity. Trans-feminine individuals may benefit from culturally sensitive and clinically competent mental health services to alleviate internalized transnegativity and psychological distress.
Internal stresses in steel plate generated by shape memory alloy inserts
International Nuclear Information System (INIS)
Malard, B.; Pilch, J.; Sittner, P.; Davydov, V.; Sedlák, P.; Konstantinidis, K.; Hughes, D.J.
2012-01-01
Graphical abstract: Display Omitted Highlights: ► Thermoresponsive internal stresses introduced into steel by embedding SMA inclusions. ► Neutron strain scanning on steel plate coupons with NiTi inserts at 21 °C and 130 °C. ► Internal stress field in steel evaluated directly from strains and by FE simulation. ► Internal stress generation by SMA insert resistant to thermal and mechanical fatigue. - Abstract: Neutron strain scanning was employed to investigate the internal stress fields in steel plate coupons with embedded prestrained superelastic NiTi shape memory alloy inserts. Strain fields in steel were evaluated at T = 21 °C and 130 °C on virgin coupons as well as on mechanically and thermally fatigued coupons. Internal stress fields were evaluated by direct calculation of principal stress components from the experimentally measured lattice strains as well as by employing an inverse finite element modeling approach. It is shown that if the NiTi inserts are embedded into the elastic steel matrix following a carefully designed technological procedure, the internal stress fields vary with temperature in a reproducible and predictable way. It is estimated that this mechanism of internal stress generation can be safely applied in the temperature range from −20 °C to 150 °C and is relatively resistant to thermal and mechanical fatigue. The predictability and fatigue endurance of the mechanism are of essential importance for the development of future smart metal matrix composites or smart structures with embedded shape memory alloy components.
Energy Technology Data Exchange (ETDEWEB)
Deister, F.; Hirschel, E.H. [Univ. Stuttgart, IAG, Stuttgart (Germany); Waymel, F.; Monnoyer, F. [Univ. de Valenciennes, LME, Valenciennes (France)
2003-07-01
An automatic adaptive hybrid Cartesian grid generation and simulation system is presented together with applications. The primary computational grid is an octree Cartesian grid. A quasi-prismatic grid may be added for resolving the boundary layer region of viscous flow around the solid body. For external flow simulations the flow solver TAU from the ''deutsche zentrum fuer luft- und raumfahrt (DLR)'' is integrated in the simulation system. Coarse grids are generated automatically, which are required by the multilevel method. As an application to an internal problem the thermal and dynamic modeling of a subway station is presented. (orig.)
Suppression of m = 0 in a RFP by toroidal field coils
International Nuclear Information System (INIS)
Alexander, D.; Robertson, S.
1993-01-01
The Reversatron RFP is normally operated with the toroidal field coils connected in series. The time-integrated voltage applied to the circuit determines the sum of the fluxes linking each turn but not the flux within each turn. Each winding may have a different flux determined by the external drive and by currents within the plasma. A parallel connection of the field coils results in the flux within each coil being determined by the volt-seconds applied to the windings; thus the toroidal flux is the same within each coil. This configuration suppresses any toroidal variation in the toroidal flux and effectively reduces the level of the m = 0 component of the radial field. The m = 0 fluctuations are expected to arise due to nonlinear coupling of the m = 1 modes. A parallel connection of field coils is impractical due to the low impedance required for driving the coils. The authors have tested the effect of parallel connected coils by adding an auxiliary set of 36 coils. These are connected in parallel but are not connected to any supply. The toroidal flux is generated by the series-connected coils which generate voltage but not current in the parallel-connected coils. With the auxiliary coils, the discharge duration is increased from 500 to 550 μsec, the plasma current is increased from 50 kA to 60 kA, F is more negative, Θ is larger, and there is less shot-to-shot variation in the discharges. The m = 0 fluctuations measured by 43 surface coils are, however, only slightly reduced
Structure of DNA toroids and electrostatic attraction of DNA duplexes
International Nuclear Information System (INIS)
Cherstvy, A G
2005-01-01
DNA-DNA electrostatic attraction is considered as the driving force for the formation of DNA toroids in the presence of DNA condensing cations. This attraction comes from the DNA helical charge distribution and favours hexagonal toroidal cross-sections. The latter is in agreement with recent cryo-electron microscopy studies on DNA condensed with cobalt hexammine. We treat the DNA-DNA interactions within the modern theory of electrostatic interaction between helical macromolecules. The size and thickness of the toroids is calculated within a simple model; other models of stability of DNA toroids are discussed and compared
The SSC superconducting air core toroid design development
International Nuclear Information System (INIS)
Fields, T.; Carroll, A.; Chiang, I.H.; Frank, J.S.; Haggerty, J.; Littenberg, L.; Morse, W.; Strand, R.C.; Lau, K.; Weinstein, R.; McNeil, R.; Friedman, J.; Hafen, E.; Haridas, P.; Kendall, H.W.; Osborne, L.; Pless, I.; Rosenson, L.; Pope, B.; Jones, L.W.; Luton, J.N.; Bonanos, P.; Marx, M.; Pusateri, J.A.; Favale, A.; Gottesman, S.; Schneid, E.; Verdier, R.
1990-01-01
Superconducting air core toroids show great promise for use in a muon spectrometer for the SSC. Early studies by SUNY at Stony Brook funded by SSC Laboratory, have established the feasibility of building magnets of the required size. The toroid spectrometer consists of a central toroid with two end cap toroids. The configuration under development provides for muon trajectory measurement outside the magnetic volume. System level studies on support structure, assembly, cryogenic material selection, and power are performed. Resulting selected optimal design and assembly is described. 4 refs., 6 figs
Form factor of some types of toroidal solenoids
International Nuclear Information System (INIS)
Koryavko, V.I.; Litvinenko, Yu.A.
1979-01-01
Obtained were the type of dependence between consumed power and formed field for toroidal helical-wound solenoids and the expression for the form factor analogous to the Fabry coefficient for cylindrical solenoids. Determined were optimum dimensions of the helical winding of ''forceless'' toroidal solenoids satisfying the condition of the formation of maximum field at minimum consumed power. Investigations also covered some types of conventional toroidal solenoids. Presented in the paper diagrams permitted to chose dimensions of the considered toroidal solenoids according to their consumed power and winding material volume
International Nuclear Information System (INIS)
Luo, Y Y; Xiao, Y X; Wang, Z W
2013-01-01
Using tidal energy can reduce environment pollution, save conventional energy and improve energy structure, hence it presents great advantage and is developing potential. Influenced by flood tide and low tide, a fully functional tidal power station needs to experience six operating modes, including bidirectional generation, pumping and sluice; the internal unsteady flow pattern and dynamic characters are very complicated. Based on a bidirectional tidal generator unit, three-dimensional unsteady flows in the flow path were calculated for four typical operating conditions with the pressure pulsation characteristics analyzed. According to the numerical results, the internal flow characteristics in the flow path were discussed. The influence of gravity to the hydraulic performance and flow characteristics were analysed. The results provide a theoretical analysis method of the hydraulic optimization design of the same type unit as well as a direction for stable operation and optimal scheduling of existing tidal power unit
Liquid toroidal drop under uniform electric field
Zabarankin, Michael
2017-06-01
The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor's discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q=(2R2+3R+2)/(7R2), where R and Q are ratios of the phases' electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, CaE, that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (CaE=0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some CaE>0. This work finds Q and CaE such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4π/3 is qualitatively stationary-the normal velocity of the drop's interface is minute and the interface coincides visually with a streamline. The found Q and CaE depend on R and ρ, and for large ρ, e.g. ρ≥3, they have simple approximations: Q˜(R2+R+1)/(3R2) and CaE∼3 √{3 π ρ / 2 } (6 ln ρ +2 ln [96 π ]-9 )/ (12 ln ρ +4 ln [96 π ]-17 ) (R+1 ) 2/ (R-1 ) 2.
Review of the Advanced Toroidal Facility program
International Nuclear Information System (INIS)
Lyon, J.F.; Murakami, M.
1987-01-01
This report summarizes the history and design goals of the Advanced Toroidal Facility (ATF). The ATF is nearing completion at ORNL with device completion expected in May 1987 and first useful plasma operation in June/July 1987. ATF is a moderate-aspect-ratio torsatron, the world's largest stellarator facility with R = 2.1 m, α bar = 0.3 m and B = 2 T (5-s pulse) or 1 T (steady-state capability). It has been specifically designed to support the US tokamak program by studying important toroidal confinement issues in a similar magnetic geometry that allows external control of the magnetic configuration properties and their radial profiles: transform, shear, well depth, shaping, axis topology, etc. ATF will operate in a current-free model which allows separation of current-driven and pressure-driven plasma behavior. It also complements the world stellarator program in its magnetic configuration (between Heliotron-E and W VII-AS) and its capabilities (large size, good access, steady state capability, second stability access, etc.). For both roles ATF will require high-power long-pulse heating to carry out its physics goals since the high power NBI pulse is limited to 0.3 s. The ATF program focuses on demonstrating the principles of high-beta, steady-state operation in toroidal geometry through its study of: (1) scaling of beta limits with magnetic configuration properties and the plasma behavior in the second stability regime; (2) transport scaling at low collisionality and the role/control of electric field; (3) control of plasma density and impurities using divertors; (4) plasma heating with NBI, ECH, ICH, and plasma fueling with gas puffing and pellet injection; and (5) optimization of the magnetic configuration
Korzhuev, M. A.
2011-02-01
It is shown that an internal combustion engine and a thermoelectric generator (TEG) arranged on the exhaust pipe of this engine come into the conflict of thermal machines that is related to using the same energy resource. The conflict grows with increasing useful electric power W e of the TEG, which leads to the limitation of both the maximum TEG output power ( W {e/max}) and the possibility of waste heat recovery in cars.
On the generation and evolution of internal solitary waves in the southern Red Sea
Guo, Daquan
2016-11-28
Satellite observations recently revealed trains of internal solitary waves (ISWs) in the off-shelf region between 16.0 degrees N and 16.5 degrees N in the southern Red Sea. The generation mechanism of these waves is not entirely clear, though, as the observed generation sites are far away (50 km) from the shelf break and tidal currents are considered relatively weak in the Red Sea. Upon closer examination of the tide properties in the Red Sea and the unique geometry of the basin, it is argued that the steep bathymetry and a relatively strong tidal current in the southern Red Sea provide favorable conditions for the generation of ISWs. To test this hypothesis and further explore the evolution of ISWs in the basin, 2-D numerical simulations with the nonhydrostatic MIT general circulation model (MITgcm) were conducted. The results are consistent with the satellite observations in regard to the generation sites, peak amplitudes and the speeds of first-mode ISWs. Moreover, our simulations suggest that the generation process of ISWs in the southern Red Sea is similar to the tide-topography interaction mechanism seen in the South China Sea. Specifically, instead of ISWs arising in the immediate vicinity of the shelf break via a hydraulic lee wave mechanism, a broad, energetic internal tide is first generated, which subsequently travels away from the shelf break and eventually breaks down into ISWs. Sensitivity runs suggest that ISW generation may also be possible under summer stratification conditions, characterized by an intermediate water intrusion from the strait of Bab el Mandeb.
Toroidal equilibrium of a non-neutral plasma with toroidal current, inertia and pressure
International Nuclear Information System (INIS)
Bhattacharyya, S.N.; Avinash, K.
1992-01-01
Equilibrium of non-neutral clouds in a toroidal vessel with toroidal magnetic field is demonstrated in the presence of a toroidal current, finite mass and finite pressure. With a toroidal current, it is shown that in a large-aspect-ratio conducting torus the equilibrium is governed by competition between forces produced by image charges and image currents. When μ 0 ε 0 E r 2 >B θ 2 (whe re E r and B θ are the self electrostatic and self magnetic fields of the cloud), the confinement is electrostatic and plasma shifts inwards; when μ 0 ε 0 E r 2 θ 2 , the confinement is magnetic and plasma shifts outwards. For μ 0 ε 0 E r 2 = B θ 2 there is no equilibrium. With finite mass or finite pressure, it is shown, in a large-aspect-ratio approximation, that the fluid drift surfaces and equipotential surfaces are displaced with respect to each other. In both cases the fluid drift surfaces are shifted inwards from the equipotential surfaces. (author)
Linear mode conversion in a toroidal plasma
International Nuclear Information System (INIS)
Hellsten, T.
1980-05-01
Linear mode conversion at the perpendicular ion cyclotron resonance has been treated for an axially symmetric toroidal plasma. The mode conversion appears between a fast electromagnetic wave and a slow-quasi electrostatic wave, due to finite electron inertia. The problem reduces to the Orr-Sommerfeld equation where the coefficients determining the reflectron, transmission and conversion are functions of the arc length along a poloidal intersection of the resonance surface. These coefficients can be determined from eigenfunctions of an ordinary differential equation. (author)
ICRH experiments in a toroidal octupole
International Nuclear Information System (INIS)
Barter, J.D.; Sprott, J.C.
1974-01-01
A 100 kW, 144 μsec pulse of 1.4 MHz rf is used to heat plasmas with densities less than or equal to 3 x 10 12 cm -3 at the ion cyclotron frequency in a toroidal octupole. The rf is coupled to the plasma by a single turn, electrostatically shielded hoop coaxial to the four main hoops and located near the wall. Absorbed power is inferred from plasma loading of the hoop and measured directly with an electrostatic ion energy analyzer and compared to single particle resonance heating theory
Electrical disruption in toroidal plasma of hydrogen
International Nuclear Information System (INIS)
Roberto, M.; Silva, C.A.B.; Goes, L.C.S.; Sudano, J.P.
1991-01-01
The initial phase of ionization of a toroidal plasma produced in hydrogen was investigated using zero-dimensional model. The model describes the temporal evolution of plasma by spatial medium of particle density and temperature, on whole plasma volume. The energy and particle (electrons and ions) balance equations are considered. The electron loss is due to ambipolar diffusion in the presence of magnetic field. The electron energy loss involves ionization, Coulomb interaction and diffusion. The ohmic heating converter gives the initial voltage necessary to disruption. (M.C.K.)
Impurity studies in the advanced toroidal facility
International Nuclear Information System (INIS)
Isler, R.C.; Horton, L.D.; Crume, E.C.; Howe, H.C.; Voronov, G.S.
1989-01-01
Impurities have played an important role in the initial stages of operation of the Advanced Toroidal Facility. Cleanup practices have been adequate enough that plasmas heated by ECH only can be operated in a quasi-steady state; however, neutral beam injected plasmas always collapse to a low temperature. It is not clear whether impurity radiation is actually responsible for initiating the collapse, but at the time the stored energy reaches a maximum, there are indications of poloidal asymmetries in radiation from low ionization stages, such as observed in marfes, which could play a dominant role in the plasma evolution. 3 refs., 5 figs
Convective cells and transport in toroidal plasmas
International Nuclear Information System (INIS)
Hassam, A.B.; Kulsrud, R.M.
1978-12-01
The properties of convective cells and the diffusion resulting from such cells are significantly influenced by an inhomogeneity in the extermal confining magnetic field, such as that in toroidal plasmas. The convective diffusion in the presence of a field inhomogeneity is estimated. For a thermal background, this diffusion is shown to be substantially smaller than classical collisional diffusion. For a model nonthermal background, the diffusion is estimated, for typical parameters, to be at most of the order of collisional diffusion. The model background employed is based on spectra observed in numerical simulations of drift-wave-driven convective cells
Energy Technology Data Exchange (ETDEWEB)
Xu, Zhaoping; Chang, Siqin [School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)
2010-04-15
A novel four-stroke free-piston engine equipped with a linear electric generator (namely internal combustion linear generator integrated power system) is proposed in this paper to achieve efficient energy conversion from fuel to electricity. Unique features of the novel power system are presented and their effects on the continuous running are discussed, along with potential advantages and disadvantages compared to conventional engines. A single cylinder, gasoline and spark ignition prototype is fabricated with reference to the geometric and control parameters of an existing conventional four-stroke engine. Stable running of the prototype is realized, and a 2.2 kW average output power with the generating efficiency of 32% has been obtained up to now. The feasibility and performance of the proposed design are verified. Detailed testing results from the continuous running prototype are analyzed in this paper for giving insight into the performance and dynamic behaviors of the novel power system. (author)
Propulsion using the electron spiral toroid
International Nuclear Information System (INIS)
Seward, Clint
1998-01-01
A new propulsion method is proposed which could potentially reduce propellant needed for space travel by three orders of magnitude. It uses the newly patented electron spiral toroid (EST), which stores energy as magnetic field energy. The EST is a hollow toroid of electrons, all spiraling in parallel paths in a thin outer shell. The electrons satisfy the coupling condition, forming an electron matrix. Stability is assured as long as the coupling condition is satisfied. The EST is held in place with a small external electric field; without an external magnetic field. The EST system is contained in a vacuum chamber. The EST can be thought of as an energetic entity, with electrons at 10,000 electron volts. Propulsion would not use combustion, but would heat propellant through elastic collisions with the EST surface and eject them for thrust. Chemical rocket combustion heats propellant to 4000 deg. C; an EST will potentially heat the propellant 29,000 times as much, reducing propellant needs accordingly. The thrust can be turned ON and OFF. The EST can be recharged as needed
Compact toroid formation, compression, and acceleration
International Nuclear Information System (INIS)
Degnan, J.H.; Bell, D.E.; Baca, G.P.; Dearborn, M.E.; Douglas, M.R.; Englert, S.E.; Englert, T.J.; Holmes, J.H.; Hussey, T.W.; Kiuttu, G.F.; Lehr, F.M.; Marklin, G.J.; Mullins, B.W.; Peterkin, R.E.; Price, D.W.; Roderick, N.F.; Ruden, E.L.; Turchi, P.J.; Coffey, S.K.; Seiler, S.W.; Bird, G.
1992-01-01
Research on the formation, compression, and acceleration of milligram Compact Toroids (CTs) will be discussed. This includes experiments with 2-stage coaxial gun discharges and calculations including 2D- MHD. The CTs are formed by 110 μf, 70 KV, 2 MA, 3 μs rise time discharges into 2 mg gas puffs in a 90 cm inner diameter, 7.6 cm gap coaxial gun with approximately 0.15 Tesla of radial-axial initial magnetic field. Reconnection at the neck of the toroidal magnetized plasma bubble extracted from the first stage gun forms the CT. Trapping, relaxation to a minimum energy Taylor state is observed with magnetic probe arrays. Low energy (few hundred KJ, 2 MA) acceleration in straight coaxial geometry, and high energy acceleration using a conical compression stage are discussed. The Phillips Laboratory 1,300 μf, 120 KV, 9.4 MJ SHIVA STAR capacitor bank is used for the acceleration discharge. The charging and triggering of the 36-module bank has been modified to permit use of any multiple of three modules. Highlights of fast photography, current, voltage, magnetic probe array, optical spectroscopy, interferometry, VUV, and higher energy radiation data and 2D-MHD calculations will be presented. Considerably more detail is presented in companion papers
Toroidal Simulations of Sawteeth with Diamagnetic Effects
Beidler, Matthew; Cassak, Paul; Jardin, Stephen
2014-10-01
The sawtooth crash in tokamaks limits the core temperature, adversely impacts confinement, and seeds disruptions. Adequate knowledge of the physics governing the sawtooth crash and a predictive capability of its ramifications has been elusive, including an understanding of incomplete reconnection, i.e., why sawteeth often cease prematurely before processing all available magnetic flux. There is an indication that diamagnetic suppression could play an important role in this phenomenon. While computational tools to study toroidal plasmas have existed for some time, extended-MHD physics have only recently been integrated. Interestingly, incomplete reconnection has been observed in simulations when diamagnetic effects are present. In the current study, we employ the three-dimensional, extended-MHD code M3D-C1 to study the sawtooth crash in a toroidal geometry. In particular, we describe how magnetic reconnection at the q = 1 rational surface evolves when self-consistently increasing diamagnetic effects are present. We also explore how the termination of reconnection may lead to core-relaxing ideal-MHD instabilities.
Toroidal deuteron accelerator for Mo-98 neutron activation
Energy Technology Data Exchange (ETDEWEB)
Araujo, Wagner L., E-mail: wagner.leite@ifnmg.edu.br, E-mail: tprcampos@pq.cnpq.br [Instituto Federal do Norte de Minas Gerais (IFN-MG), Montes Claros, MG (Brazil); Campos, Tarcisio P.R. Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear
2017-07-01
The radionuclide Tc-{sup 99m} is the most useful radioisotope in nuclear medicine. It can be produced by the Mo-99 beta minus decay. Mo-99 has often been produced in a high- flux nuclear reactor through radioactive neutron capture reactions on Mo-98. The present paper provides a preliminary design of a toroidal transmutation system (TTS) based on a toroidal compact deuteron accelerator, which can provide the Mo-98 transmutation into Mo-99. This system is essentially composed of a multi-aperture plasma electrode and a target, submitted to 180 kV, where a positive deuteron beam is accelerated toward a titanium-target loaded with deuterium in which nuclear d-d fusion reactions are induced. The Particle Studio package of the Computer Simulation Technology (CST) software was applied to design, simulate and optimize the deuteron beam on the target. MCNP code provided to neutronic analysis. Based on electromagnetic and neutronic simulations, the neutron yield and reaction rates were estimated. The simulated data allowed appraising the Mo-99 activity. A TTS, in a specific configuration, could produce a total deuterium current of 1.6 A at the target and a neutron yield of 10{sup 13} n.s{sup -1}. In a arrangement of 30 column samples, TTS provides 230 mCi s{sup -1} Mo{sup 99} in each column, which represents 80% of Tc-99m in secular equilibrium. As conclusion, the system holds potential for generating Mo-99 and Tc-99m in a suitable activity in secular equilibrium. (author)
Transport and Dynamics in Toroidal Fusion Systems
Energy Technology Data Exchange (ETDEWEB)
Schnack, Dalton D
2006-05-16
This document reports the successful completion of the OFES Theory Milestone for FY2005, namely, Perform parametric studies to better understand the edge physics regimes of laboratory experiments. Simulate at increased resolution (up to 20 toroidal modes), with density evolution, late into the nonlinear phase and compare results from different types of edge modes. Simulate a single case including a study of heat deposition on nearby material walls. The linear stability properties and nonlinear evolution of Edge Localized Modes (ELMs) in tokamak plasmas are investigated through numerical computation. Data from the DIII-D device at General Atomics (http://fusion.gat.com/diii-d/) is used for the magnetohydrodynamic (MHD) equilibria, but edge parameters are varied to reveal important physical effects. The equilibrium with very low magnetic shear produces an unstable spectrum that is somewhat insensitive to dissipation coefficient values. Here, linear growth rates from the non-ideal NIMROD code (http://nimrodteam.org) agree reasonably well with ideal, i.e. non-dissipative, results from the GATO global linear stability code at low toroidal mode number (n) and with ideal results from the ELITE edge linear stability code at moderate to high toroidal mode number. Linear studies with a more realistic sequence of MHD equilibria (based on DIII-D discharge 86166) produce more significant discrepancies between the ideal and non-ideal calculations. The maximum growth rate for the ideal computations occurs at toroidal mode index n=10, whereas growth rates in the non-ideal computations continue to increase with n unless strong anisotropic thermal conduction is included. Recent modeling advances allow drift effects associated with the Hall electric field and gyroviscosity to be considered. A stabilizing effect can be observed in the preliminary results, but while the distortion in mode structure is readily apparent at n=40, the growth rate is only 13% less than the non-ideal MHD
Modelling of the toroidal asymmetry of poloidal halo currents in conducting structures
International Nuclear Information System (INIS)
Pomphrey, N.; Bialek, J.M.; Part, W.
1998-01-01
During plasma disruptions, substantial toroidal and poloidal eddy currents are generated in the vacuum vessel and other plasma facing conducting structures. Eddy currents that conduct charge through paths which close through the plasma periphery are called halo currents, and these can be of substantial magnitude. Of particular concern for tokamak design and operation is the observed toroidal asymmetry of the halo current distribution: such an asymmetric distribution leads to problematic non-uniform forces on the conducting structures. The premise is adopted that the source of toroidal asymmetry is the plasma deformation resulting from the non-linear external kink instability that develops during the current quench phase of a disruption. A simple model is presented of the kinked plasma that allows an analytic calculation of the dependence of the toroidal peaking factor (TPF) on the ratio of the halo current to the total toroidal plasma current, I h /I p . Expressions for the TPF as a function of I h /I p are derived for m/n=2/1 and m/n=1/1 helical instabilities. The expressions depend on a single parameter, which measures the amplitude of the saturated state of the kink instability. A comparison with disruption data from experiments shows good agreement. Numerical experiments that simulate non-linear external kinks provide guidance on the values expected for the saturated amplitude. It is proposed that a simple plasma halo model is adequate for assessing the engineering impact of asymmetric halo currents, since the force distribution on the conducting structures depends mainly on the 'resistive distribution' of the eddy currents. A brief description is given of an electromagnetics code that calculates the time development of eddy currents in conducting structures, and the code is applied to two halo current disruption scenarios. These are used to emphasize the importance of having an accurate eddy current calculation to correctly estimate the engineering impact of
Next Generation Safeguards Initiative Workshop on Enhanced Recruiting for International Safeguards
Energy Technology Data Exchange (ETDEWEB)
Pepper,S.; Rosenthal, M.; Fishbone, L.; Occhiogrosso, D.; Carroll, C.; Dreicer, M.; Wallace, R.; Rankhauser, J.
2008-10-22
In 2007, the National Nuclear Security Administration's Office of Nonproliferation and International Security (NA-24) completed a yearlong review of the challenges facing the international safeguards system today and over the next 25 years. The study found that without new investment in international safeguards, the U.S. safeguards technology base, and our ability to support International Atomic Energy Agency (IAEA) safeguards, will continue to erode and soon may be at risk. To reverse this trend, the then U.S. Secretary of Energy, Samuel Bodman, announced at the 2007 IAEA General Conference that the Department of Energy (DOE) would launch the Next Generation Safeguards Initiative (NGSI). He stated 'IAEA safeguards must be robust and capable of addressing proliferation threats. Full confidence in IAEA safeguards is essential for nuclear power to grow safely and securely. To this end, the U.S. Department of Energy will seek to ensure that modern technology, the best scientific expertise, and adequate resources are available to keep pace with expanding IAEA responsibilities.' To meet this goal, the NGSI objectives include the recruitment of international safeguards experts to work at the U.S. national laboratories and to serve at the IAEA's headquarters. Part of the latter effort will involve enhancing our existing efforts to place well-qualified Americans in a sufficient number of key safeguards positions within the IAEA's Department of Safeguards. Accordingly, the International Safeguards Project Office (ISPO) at Brookhaven National Laboratory (BNL) hosted a Workshop on Enhanced Recruiting for International Safeguards (ERIS) on October 22 and 23, 2008. The ISPO used a workshop format developed earlier with Sonalysts, Inc., that was followed at the U.S. Support Program's (USSP's) technology road-mapping sessions. ISPO invited participants from the U.S. DOE, the IAEA, the U.S. national laboratories, private industry, academia, and
Low-frequency fluctuations in a pure toroidal magnetized plasma
Indian Academy of Sciences (India)
A magnetized, low- plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼ 1011 cm-3, ∼ 4 × 1010 cm-3 and ∼ 2 × 1010 cm−3 respectively.
Toroidal asymmetries in divertor impurity influxes in NSTX
Directory of Open Access Journals (Sweden)
F. Scotti
2017-08-01
Full Text Available Toroidal asymmetries in divertor carbon and lithium influxes were observed in NSTX, due to toroidal differences in surface composition, tile leading edges, externally-applied three-dimensional (3D fields and toroidally-localized edge plasma modifications due to radio frequency heating. Understanding toroidal asymmetries in impurity influxes is critical for the evaluation of total impurity sources, often inferred from measurements with a limited toroidal coverage. The toroidally-asymmetric lithium deposition induced asymmetries in divertor lithium influxes. Enhanced impurity influxes at the leading edge of divertor tiles were the main cause of carbon toroidal asymmetries and were enhanced during edge localized modes. Externally-applied 3D fields led to strike point splitting and helical lobes observed in divertor impurity emission, but marginal changes to the toroidally-averaged impurity influxes. Power coupled to the scrape-off layer SOL plasma during radio frequency (RF heating of H-mode discharges enhanced impurity influxes along the non-axisymmetric divertor footprint of flux tubes connecting to plasma in front of the RF antenna.
2-D skin-current toroidal-MHD-equilibrium code
International Nuclear Information System (INIS)
Feinberg, B.; Niland, R.A.; Coonrod, J.; Levine, M.A.
1982-09-01
A two-dimensional, toroidal, ideal MHD skin-current equilibrium computer code is described. The code is suitable for interactive implementation on a minicomptuer. Some examples of the use of the code for design and interpretation of toroidal cusp experiments are presented
Energy Technology Data Exchange (ETDEWEB)
Frassetto, F.; Poletto, L., E-mail: poletto@dei.unipd.it [National Research Council, Institute of Photonics and Nanotechnologies, via Trasea 7, 35131 Padova (Italy); Trabattoni, A.; Anumula, S.; Sansone, G. [Department of Physics, Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano (Italy); Calegari, F. [National Research Council, Institute of Photonics and Nanotechnologies, Piazza L. da Vinci 32, 20133 Milano (Italy); Nisoli, M. [Department of Physics, Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano (Italy); National Research Council, Institute of Photonics and Nanotechnologies, Piazza L. da Vinci 32, 20133 Milano (Italy)
2014-10-15
We have developed a novel attosecond beamline designed for attosecond-pump/attosecond probe experiments. Microfocusing of the Extreme-ultraviolet (XUV) radiation is obtained by using a coma-compensated optical configuration based on the use of three toroidal mirrors controlled by a genetic algorithm. Trains of attosecond pulses are generated with a measured peak intensity of about 3 × 10{sup 11} W/cm{sup 2}.
International Nuclear Information System (INIS)
Frassetto, F.; Poletto, L.; Trabattoni, A.; Anumula, S.; Sansone, G.; Calegari, F.; Nisoli, M.
2014-01-01
We have developed a novel attosecond beamline designed for attosecond-pump/attosecond probe experiments. Microfocusing of the Extreme-ultraviolet (XUV) radiation is obtained by using a coma-compensated optical configuration based on the use of three toroidal mirrors controlled by a genetic algorithm. Trains of attosecond pulses are generated with a measured peak intensity of about 3 × 10 11 W/cm 2
International Nuclear Information System (INIS)
Lim, S C; Teo, L P
2008-01-01
Quartic self-interacting fractional Klein-Gordon scalar massive and massless field theories on toroidal spacetime are studied. The effective potential and topologically generated mass are determined using zeta-function regularization technique. Renormalization of these quantities are derived. Conditions for symmetry breaking are obtained analytically. Simulations are carried out to illustrate regions or values of compactified dimensions where symmetry-breaking mechanisms appear
International Nuclear Information System (INIS)
Long, Jon D.; McGinnis, Brent R.; Morgan, James B.; Whitaker, Michael; Lockwood, Dunbar; Shipwash, Jacqueline L.
2011-01-01
The Third International Meeting on Next Generation Safeguards (NGS3) was hosted by the U.S. Department of Energy (DOE)/National Nuclear Security Administration's (NNSA) Office of Nonproliferation and International Security (NIS) in Washington, D.C. on 14-15 December 2010; this meeting focused on the Safeguards-by-Design (SBD) concept. There were approximately 100 participants from 13 countries, comprised of safeguards policy and technical experts from government and industry. Representatives also were present from the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), the European Atomic Energy Agency (Euratom), and the International Atomic Energy Agency (IAEA). The primary objective of this meeting was to exchange views and provide recommendations on implementation of the SBD concept for four specific nuclear fuel cycle facility types: gas centrifuge enrichment plants (GCEPs), GEN III and GEN IV reactors, aqueous reprocessing plants, and mixed oxide fuel fabrication facilities. The general and facility-specific SBD documents generated from the four working groups, which were circulated for comment among working group participants, are intended to provide a substantive contribution to the IAEA's efforts to publish SBD guidance for these specific types of nuclear facilities in the near future. The IAEA has described the SBD concept as an approach in which 'international safeguards are fully integrated into the design process of a new nuclear facility from the initial planning through design, construction, operation, and decommissioning.' As part of the Next Generation Safeguards Initiative (NGSI), the DOE is working to establish SBD as a global norm through DOE laboratory studies, international workshops, engagement with industry and the IAEA, and setting an example through its use in new nuclear facilities in the United States. This paper describes the discussion topics and final recommendations of the Enrichment Facilities Working
Impact of financial institution environmental guidelines on international power generation projects
International Nuclear Information System (INIS)
Macak, J.J. III; Schott, G.A.
1995-01-01
Where financing is concerned, two major players for US based international power projects are The World Bank and the Export-Import Bank of the US (Ex-Im Bank). The concern for environmental protection is a global issue, yet many countries still have no enforceable environmental regulations for power generation facilities. In the past, many projects were developed with little or no environmental controls. However, designing a power generation project to meet The World Bank environmental guidelines is now generally regarded as standard practice for independent power projects in the developing world (Price et al, 1994). The World Bank standards are mandatory for projects financed by The World Bank, through the International Finance Corporation (IFC), or associated programs like the Expanded Cofinancing Program of the International Bank for Reconstruction and Development (IBRD). The Ex-Im Bank has recently established new environmental procedures and guidelines that went into effect on February 1, 1995. In order to avoid a competitive disadvantage for US exporters and still provide a means for global environmental protection, Ex-Im Bank has taken a leadership role in encouraging the adoption of common environmental procedures and standards by leading export credit agencies around the world. Until such procedures are established, Ex-Im Bank is seeking to establish common lines in specific cases with the Organization for Economic Cooperation and Development (OECD) on environmental standards for appropriate projects (Ex-Im, 1994)
Dossmann, Yvan; Paci, Alexandre; Auclair, Francis; Floor, Jochem
2010-05-01
Internal tides are suggested to play a major role in the sustaining of the global oceanic circulation [1][5]. Although the exact origin of the energy conversions occurring in stratified fluids is questioned [2], it is clear that the diapycnal energy transfers provided by the energy cascade of internal gravity waves generated at tidal frequencies in regions of steep bathymetry is strongly linked to the general circulation energy balance. Therefore a precise quantification of the energy supply by internal waves is a crucial step in forecasting climate, since it improves our understanding of the underlying physical processes. We focus on an academic case of internal waves generated over an oceanic ridge in a linearly stratified fluid. In order to accurately quantify the diapycnal energy transfers caused by internal waves dynamics, we adopt a complementary approach involving both laboratory and numerical experiments. The laboratory experiments are conducted in a 4m long tank of the CNRM-GAME fluid mechanics laboratory, well known for its large stratified water flume (e.g. Knigge et al [3]). The horizontal oscillation at precisely controlled frequency of a Gaussian ridge immersed in a linearly stratified fluid generates internal gravity waves. The ridge of e-folding width 3.6 cm is 10 cm high and spans 50 cm. We use PIV and Synthetic Schlieren measurement techniques, to retrieve the high resolution velocity and stratification anomaly fields in the 2D vertical plane across the ridge. These experiments allow us to get access to real and exhaustive measurements of a wide range of internal waves regimes by varying the precisely controlled experimental parameters. To complete this work, we carry out some direct numerical simulations with the same parameters (forcing amplitude and frequency, initial stratification, boundary conditions) as the laboratory experiments. The model used is a non-hydrostatic version of the numerical model Symphonie [4]. Our purpose is not only to
Energy Technology Data Exchange (ETDEWEB)
McConnell, R.; Symko-Davies, M.; Hayden, H.
2005-05-01
The International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen provides an opportunity to learn about current significant research on solar concentrators for generating electricity or hydrogen. The conference will emphasize in-depth technical discussions of recent achievements in technologies that convert concentrated solar radiation to electricity or hydrogen, with primary emphasis on photovoltaic (PV) technologies. Very high-efficiency solar cells--above 37%--were recently developed, and are now widely used for powering satellites. This development demands that we take a fresh look at the potential of solar concentrators for generating low-cost electricity or hydrogen. Solar electric concentrators could dramatically overtake other PV technologies in the electric utility marketplace because of the low capital cost of concentrator manufacturing facilities and the larger module size of concentrators. Concentrating solar energy also has advantages for th e solar generation of hydrogen. Around the world, researchers and engineers are developing solar concentrator technologies for entry into the electricity generation market and several have explored the use of concentrators for hydrogen production. The last conference on the subject of solar electric concentrators was held in November of 2003 and proved to be an important opportunity for researchers and developers to share new and crucial information that is helping to stimulate projects in their countries.
Formation of a compact toroid for enhanced efficiency
Energy Technology Data Exchange (ETDEWEB)
Mozgovoy, A. G. [P.N. Lebedev Physical Institute, Moscow 119991 (Russian Federation); Romadanov, I. V.; Ryzhkov, S. V., E-mail: ryzhkov@power.bmstu.ru [Bauman Moscow State Technical University, Moscow 105005 (Russian Federation)
2014-02-15
We report here our results on the formation of a plasma configuration with the generic name of compact toroid (CT). A method of compact toroid formation to confine, heat and compress a plasma is investigated. Formation of a compact torus using an additional toroidal magnetic field helps to increase the plasma current to a maintainable level of the original magnetic field. We design the Compact Toroid Challenge (CTC) experiment in order to improve the magnetic flux trapping during field reversal in the formation of a compact toroid. The level of the magnetic field immersed in the plasma about 70% of the primary field is achieved. The CTC device and scheme of high level capturing of magnetic flux are presented.
Mechanical Commissioning of the ATLAS Barrel Toroid Magnet
Foussat, A; Dudarev, A; Bajas, H; Védrine, P; Berriaud, C; Sun, Z; Sorbi, M
2008-01-01
ATLAS is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider. Its features include the 4 T Barrel Toroid magnet, the largest superconducting magnet (25 m long, 20 m diameter) that provides the magnetic field for the ATLAS muon spectrometer. The coils integrated at CERN, were tested individually at maximum current of 22 kA in 2005. Following the mechanical assembly of the Barrel Toroid in the ATLAS underground cavern, the test of the full Barrel Toroid was performed in October 2006. Further tests are foreseen at the end 2007 when the system will include the two End Cap Toroids (ECT). The paper gives an overview of the good mechanical test results achieved in comparison with model predictions and the experience gained in the mechanical behavior of the ATLAS Toroidal coils is discussed.
Analysis of MHD equilibria by toroidal multipolar expansions
International Nuclear Information System (INIS)
Alladio, F.; Crisanti, F.
1986-01-01
The use of fully toroidal co-ordinates permits the two-dimensional problem of the axisymmetric plasma toroidal equilibrium to be reduced to the one-dimensional problem of determining a limited number of its toroidal multipolar moments. This has allowed the creation of a fast semi-analytic predictive equilibrium code that can be used in both free and fixed boundary conditions for plasmas with circular or mildly non-circular cross-section. The concept of toroidal multipoles is also particularly suitable for the analysis of experimental data from magnetic probe measurements and clarifies the conditions under which the plasma thermal and electrical self-inductances βsub(p) and lsub(i) can be estimated separately. Finally, the interpretation of the magnetic equilibrium measurements in terms of toroidal multipoles can directly provide the boundary conditions for a fast equilibrium reconstruction code. Examples of the application of such a code to the JET magnetic measurements are reported. (author)
Internalizing externalities of electricity generation: An analysis with MESSAGE-MACRO
International Nuclear Information System (INIS)
Klaassen, Ger; Riahi, Keywan
2007-01-01
This paper examines the global impacts of a policy that internalizes the external costs (related to air pollution damage, excluding climate costs) of electricity generation using a combined energy systems and macroeconomic model. Starting point are estimates of the monetary damage costs for SO 2 , NO X , and PM per kWh electricity generated, taking into account the fuel type, sulfur content, removal technology, generation efficiency, and population density. Internalizing these externalities implies that clean and advanced technologies increase their share in global electricity production. Particularly, advanced coal power plants, natural gas combined cycles, natural gas fuel cells, wind and biomass technologies gain significant market shares at the expense of traditional coal- and gas-fired plants. Global carbon dioxide emissions are lowered by 3% to 5%. Sulfur dioxide emissions drop significantly below the already low level. The policy increases the costs of electricity production by 0.2 (in 2050) to 1.2 Euro cent/kWh (in 2010). Gross domestic product losses are between 0.6% and 1.1%. They are comparatively high during the initial phase of the policy, pointing to the need for a gradual phasing of the policy
Control of Compact-Toroid Characteristics by External Copper Shell
Matsumoto, T.; Sekiguchi, J.; Asai, T.; Gota, H.; Roche, T.; Allfrey, I.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; the TAE Team
2015-11-01
A collaborative research project by Tri Alpha Energy and Nihon University has been conducted for several years, which led to the development of a new compact toroid (CT) injector for efficient FRC particle refueling in the C-2U experiment. The CT is formed by a magnetized coaxial plasma gun (MCPG), consisting of coaxial cylindrical electrodes. In CT formation via MCPG, the magnetic helicity content of the generated CT is one of the critical parameters. A bias coil is inserted into the inner electrode to generate a poloidal flux. The resultant bias magnetic field is spread out of MCPG with time due to its low-frequency bias current. To obtain a more effectively distributed bias magnetic field as well as to improve the voltage breakdown between electrodes, the MCPG incorporates a novel ~ 1 mm thick copper shell mounted outside of the outer electrode. This allows for reliable and controlled operation and more robust CT generation. A detailed discussion of the copper shell and experimental test results will be presented.
Mokhtar, N. F. M.; Khalid, I. K.; Siri, Z.; Ibrahim, Z. B.; Gani, S. S. A.
2017-10-01
The influences of feedback control and internal heat source on the onset of Rayleigh-Bénard convection in a horizontal nanofluid layer is studied analytically due to Soret and Dufour parameters. The confining boundaries of the nanofluid layer (bottom boundary-top boundary) are assumed to be free-free, rigid-free, and rigid-rigid, with a source of heat from below. Linear stability theory is applied, and the eigenvalue solution is obtained numerically using the Galerkin technique. Focusing on the stationary convection, it is shown that there is a positive thermal resistance in the presence of feedback control on the onset of double-diffusive convection, while there is a positive thermal efficiency in the existence of internal heat generation. The possibilities of suppress or augment of the Rayleigh-Bénard convection in a nanofluid layer are also discussed in detail.
Total internal reflection second-harmonic generation: probing the alkane water interface
International Nuclear Information System (INIS)
Conboy, J.C.; Daschbach, J.L.; Richmond, G.L.
1994-01-01
Total internal reflection Second-Harmonic Generation (SHG) has been used to study a series of neat n-alkane/water interfaces. Polarization and incident angular-dependent measurements of the SH response show good agreement with theoretical predictions. Analysis of the incident and polarization angular-dependent SH response allows for determination of the nonlinear optical properties of molecules comprising the interfacial region. Based on Kleinman symmetry, the measured surface nonlinear susceptibilities suggest a high degree of interfacial order for octane and decane with less order indicated by the odd carbon n-alkanes examined, heptane and nonane. The SH response in reflection and transmission has been measured under a Total Internal Reflection (TIR) of the fundamental. The measured nonlinear susceptibilities in each case are found to be identical. (orig.)
International Nuclear Information System (INIS)
Manach, P.Y.; Favier, D.; Rio, G.
1996-01-01
The aim of this paper is to analyse the generation of internal stresses during the predeformation of NiTi shape memory alloys in the martensitic state. This allows to determine the initial stress state in which the material will transform during the shape memory effect due to heating consecutively to this prestrain. In that way a three-dimensional finite element model of the deformation of shape memory alloys has been developed, the constitutive law being defined using an elastohysteresis tensor model. The influence of behavioural and geometrical factors are illustrated considering the numerical simulation of different cases of practical importance for industrial applications : the study of the bending behaviour of a NiTi cantilever beam as well as the study of the swelling of a pipe connection under both uniform and non uniform internal displacement fields. (orig.)
Pandya, M. D.; Ennis, D. A.; Hartwell, G. J.; Maurer, D. A.
2015-11-01
Low edge safety factor operation at a value less than two (q (a) = 1 /ttot (a) routine on the Compact Toroidal Hybrid device. Presently, the operational space of this current carrying stellarator extends down to q (a) = 1 . 2 without significant n = 1 kink mode activity after the initial plasma current rise of the discharge. The disruption dynamics of these low q (a) plasmas depend upon the fraction of rotational transform produced by external stellarator coils to that generated by the plasma current. We observe that when about 10% of the total rotational transform is supplied by the stellarator coils, low q (a) disruptions are passively suppressed and avoided even though q (a) disrupt, the instability precursors measured and implicated as the cause are internal tearing modes with poloidal, m, and toroidal, n, mode numbers of m / n = 3 / 2 and 4 / 3 observed by external magnetic sensors, and m / n = 1 / 1 activity observed by core soft x-ray emissivity measurements. Even though q (a) passes through and becomes much less than two, external n = 1 kink mode activity does not appear to play a significant role in the observed disruption phenomenology. This work is supported by US Department of Energy Grant No. DE-FG02-00ER54610.
Internal fire analysis screening methodology for the Salem Nuclear Generating Station
International Nuclear Information System (INIS)
Eide, S.; Bertucio, R.; Quilici, M.; Bearden, R.
1989-01-01
This paper reports on an internal fire analysis screening methodology that has been utilized for the Salem Nuclear Generating Station (SNGS) Probabilistic Risk Assessment (PRA). The methodology was first developed and applied in the Brunswick Steam Electric Plant (BSEP) PRA. The SNGS application includes several improvements and extensions to the original methodology. The SNGS approach differs significantly from traditional fire analysis methodologies by providing a much more detailed treatment of transient combustibles. This level of detail results in a model which is more usable for assisting in the management of fire risk at the plant
The International Geomagnetic Reference Field (IGRF) generation 12: BGS candidates and final models
Beggan, Ciaran D.; Hamilton, Brian; Taylor, Victoria; Macmillan, Susan; Thomson, Alan
2015-01-01
The International Geomagnetic Reference Field (IGRF) model is a reference main field magnetic model updated on a quinquennial basis. The latest revision (generation 12) was released in January 2015. The IGRF-12 consists of a definitive model (DGRF2010) of the main field for 2010.0, a model for the field at 2015.0 (IGRF2015) and a prediction of secular variation (IGRF-12 SV) for the forthcoming five years until 2020.0. The remaining coefficients of IGRF-12 are unchanged from IGRF-11. Nin...
The Next Generation of Axion Helioscopes: The International Axion Observatory (IAXO)
DEFF Research Database (Denmark)
Vogel, J.K.; Armengaud, E.; Avignone, F.T.
2015-01-01
The International Axion Observatory (IAXO) is a proposed 4th-generation axion helioscope with the primary physics research goal to search for solar axions via their Primakoff conversion into photons of 1 – 10 keV energies in a strong magnetic field. IAXO will achieve a sensitivity to the axion-ph...... low background x-ray detectors. The magnet will be built into a structure with elevation and azimuth drives that will allow solar tracking for 12hours each day. This contribution is a summary of our papers [1–3] and we refer to these for further details....
Jones, Harry W.
2016-01-01
A review of two papers on improving the International Space Station (ISS) Oxygen Generation Assembly (OGA) shows that it would not save substantial mass on a Mars transit. The ISS OGA requires redesign for satisfactory operation, even for the ISS. The planned improvements of the OGA for ISS would not be sufficient to make it suitable for Mars, because Mars transit life support has significantly different requirements than ISS. The OGA for Mars should have lower mass, better reliability and maintainability, greater safety, radiation hardening, and capability for quiescent operation. NASA's methodical, disciplined systems engineering process should be used to develop the appropriate system.
Energy Technology Data Exchange (ETDEWEB)
Albert, Christopher G.; Heyn, Martin F.; Kapper, Gernot; Kernbichler, Winfried; Martitsch, Andreas F. [Fusion@ÖAW, Institut für Theoretische Physik - Computational Physics, Technische Universität Graz, Petersgasse 16, 8010 Graz (Austria); Kasilov, Sergei V. [Fusion@ÖAW, Institut für Theoretische Physik - Computational Physics, Technische Universität Graz, Petersgasse 16, 8010 Graz (Austria); Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology,” ul. Akademicheskaya 1, 61108 Kharkov (Ukraine)
2016-08-15
Toroidal torque generated by neoclassical viscosity caused by external non-resonant, non-axisymmetric perturbations has a significant influence on toroidal plasma rotation in tokamaks. In this article, a derivation for the expressions of toroidal torque and radial transport in resonant regimes is provided within quasilinear theory in canonical action-angle variables. The proposed approach treats all low-collisional quasilinear resonant neoclassical toroidal viscosity regimes including superbanana-plateau and drift-orbit resonances in a unified way and allows for magnetic drift in all regimes. It is valid for perturbations on toroidally symmetric flux surfaces of the unperturbed equilibrium without specific assumptions on geometry or aspect ratio. The resulting expressions are shown to match the existing analytical results in the large aspect ratio limit. Numerical results from the newly developed code NEO-RT are compared to calculations by the quasilinear version of the code NEO-2 at low collisionalities. The importance of the magnetic shear term in the magnetic drift frequency and a significant effect of the magnetic drift on drift-orbit resonances are demonstrated.
International Nuclear Information System (INIS)
Jeong, Dae Kyung; Kang, Jin-Ho; Ryu, Sang-Wan; Ha, Jun-Seok
2017-01-01
A NiO/GaN heterojunction piezoelectric generator was fabricated, and the improvement in device performance was analyzed. The electrical properties of NiO were varied by regulating the gas environment during sputtering. An optimized NiO layer was adopted for high piezoelectric voltage generation. Internal carrier screening was revealed to be the dominant mechanism degrading the piezoelectric performance, necessitating the suppression of carrier screening. The highly resistive NiO layer was advantageous in the suppression of carrier transport across the junction that screened the piezoelectric field. The maximum piezoelectric voltage and current density values obtained were 7.55 V and 1.14 µ A cm −2 , respectively. The power obtained was sufficient to operate a light-emitting diode combined with a charging circuit. (paper)
Energy Technology Data Exchange (ETDEWEB)
Shehzad, S.A., E-mail: ali_qau70@yahoo.com [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Abdullah, Z. [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Abbasi, F.M. [Department of Mathematics, Comsats Institute of Information Technology, Islamabad 44000 (Pakistan); Hayat, T. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan)
2016-01-01
This research work addresses the three-dimensional hydromagnetic flow of Jeffrey fluid with nanoparticles. Flow is generated by a bidirectional stretching surface. The effects of thermal radiation and internal heat generation are encountered in energy expressions. More realistic convective boundary conditions at the surface are employed instead of constant surface temperature and mass species conditions. Boundary layer assumptions lead to the governing non-linear mathematical model. Resulting equations through momentum, energy and mass species are made dimensionless using suitable variables. The solution expressions of dimensionless velocities, temperature and nanoparticle concentration have been computed for the convergent series solutions. The impacts of interesting parameters on the dimensionless quantities are displayed and interpreted. The values of physical quantities are computed and analyzed. - Highlights: • Three-dimensional hydromagnetic flow of Jeffrey nanofluid is considered. • Brownian motion and thermophoresis effects are encountered. • Heat transfer analysis is performed with thermal radiation. • Results are plotted and visualized.
Cost of generating tritium internal and external to a tokamak hybrid reactor
International Nuclear Information System (INIS)
Crotzer, M.E.; Heck, F.M.; Steinke, K.C.
1981-01-01
The costs associated with producing tritium internal and external to a thorium-based tokamak hybrid are estimated for a number of scenarios and the resulting impact on the symbiotic system cost of electricity calculated. For tritium generation within the hybrid, both continuous and batch production is analyzed. For external production, the lithium-bearing blanket is replaced with thorium and the tritium is generated in the client fission reactors. Continuous tritium production within the hybrid is found to increase the cost of electricity from 1.4 to 4.0 mills/kW-h. Batch tritium production can increase the cost of electricity by 10 mills/kW-h. Producing tritium outside the hybrid, and thereby enhancing client support, increases the cost of electricity from 1.8 to 4.1 mills/kW-h
DEFF Research Database (Denmark)
, which takes a sole focus on the electricity sector, the smart energy systems approach includes the entire energy system in its identification of suitable energy infrastructure designs and operation strategies. Focusing solely on the smart electricity grid often leads to the definition of transmission......It is a great pleasure to welcome you to the first International Conference on Smart Energy Systems and 4th Generation District Heating at Aalborg University, Copenhagen Campus on 25-26 August 2015. The conference is organised by the 4DH Strategic Research Centre in collaboration with Aalborg...... University and offers more than 70 presentations in 3 parallel sessions with more than 180 participants from 25 countries around the world. The aim is to present and discuss scientific findings and industrial experiences related to the development of Smart Energy Systems and future 4th Generation District...
Start up system for hydrogen generator used with an internal combustion engine
Houseman, J.; Cerini, D. J. (Inventor)
1977-01-01
A hydrogen generator provides hydrogen rich product gases which are mixed with the fuel being supplied to an internal combustion engine for the purpose of enabling a very lean mixture of that fuel to be used, whereby nitrous oxides emitted by the engine are minimized. The hydrogen generator contains a catalyst which must be heated to a pre-determined temperature before it can react properly. To simplify the process of heating up the catalyst at start-up time, either some of the energy produced by the engine such as engine exhaust gas, or electrical energy produced by the engine, or the engine exhaust gas may be used to heat up air which is then used to heat the catalyst.
International Nuclear Information System (INIS)
Litvinnko, Yu.A.
1982-01-01
The possibilities, as to the ultimate magnetic field strength, of tokamak magnet systems made on the base of layer-by-laeyer shrouded coils are considered numerically. The toroidal magnet system is considered which consists of N skewe, layer-by-layer shrouded, equistrong coils in the ideal torus approximation. The dependences of the ragnetic field strength on the internal- and external torus radii, pulse duration and aspect ratio for copper coils shrouded with fiberglass are calculated as an example. The analysis of the obtained results shows that using of the layer-by-layer shrouding scheme for toroidal solenoid coils leads to a considerable growth of the ultimate magnetic field strengths in a wide duration range. For example, the limiting field strength along the toroidal solenoid axis of the considered type inside the ''FT'' installation toroidal solenoid at equivalent field pulse duration of approximately 0.3 s reaches H 0 =1.3zx10 7 A/m
Effects of multi-photon interferences from internally generated fields in strongly resonant systems
International Nuclear Information System (INIS)
Deng, Lu; Payne, Marvin G.; Garrett, William R.
2006-01-01
In studies of various nonlinear optical phenomena, strong resonant features in the atomic or molecular response to multi-photon driven processes have been used to greatly enhance the visibility of otherwise weak higher-order processes. However, there are well defined circumstances where a multi-photon-resonant response of a target system leads to the generation of one or more new electromagnetic fields that can drastically change the overall system response from what would be expected from the imposed laser fields alone. New effects can occur and dominate some aspects of the nonlinear optical response because of the constructive or destructive interference between transition amplitudes along multiple excitation pathways between a given set of optically coupled states, where one of the pathways involve internally generated field(s). Under destructive interference some resonant enhancements can become completely canceled (suppressed). This review focuses on the class of optical interference effects associated with internally generated fields, that have been found to be capable of influencing a very significant number of basic physical phenomena in gas or vapor phase systems. It provides a historical overview of experimental and theoretical developments and a modern understanding of the underlying physics and its various manifestations that include: suppression of multi-photon excitation processes, suppression of stimulated emissions (Raman, hyper-Raman, and optically pumped stimulated emissions), saturation of parametric wave-mixing, pressure and beam-geometry dependent shifting of multi-photon-resonant absorption lines, and the suppression of Autler-Townes splitting and ac-stark shifts. Additionally, optical interference effects in some modern contexts, such as achieving multi-photon induced transparency, establishing single-photon self-interference based induced transparency, and generating entangled single photon states, are reviewed
Toroidal equilibrium and radial profiles from magnetic measurements in Extrap T1
International Nuclear Information System (INIS)
Brunsell, Per; Jin Li; Tennfors, Einar
1991-01-01
The toroidal equilibrium position in the Extrap T1 toroidal Z-pinch is studied by measuring the currents induced in the external octupole field rings. Radial profiles are obtained by an internal magnetic coil array. From the magnetic field, profiles of current density, plasma pressure, safety factor, resistivity and input power density are deduced. A polynomial model is developed to simulate the measured profiles. The classical ion heat conduction losses in Extrap discharges are calculated using this model and compared to the power input. for polynomials matched to magnetic field profiles measured in present experiments, these losses are small. By varying the coefficients of the polynomials, a region is found where the power input can balance the classical heat conduction losses at higher values of Θ and β o . (Author)
Toroidal confinement of non-neutral plasma - A new approach to high-beta equilibrium
International Nuclear Information System (INIS)
Yoshida, Z.; Ogawa, Y.; Morikawa, J.
2001-01-01
Departure from the quasi-neutral condition allows us to apply significant two-fluid effects that impart a new freedom to the design of high-performance fusion plasma. The self-electric field in a non-neutralized plasma induces a strong ExB-drift flow. A fast flow produces a large hydrodynamic pressure that can balance with the thermal pressure of the plasma. Basic concepts to produce a toroidal non-neutral plasma have been examined on the internal-conductor toroidal confinement device Proto-RT. A magnetic separatrix determines the boundary of the confinement region. Electrons describe chaotic orbits in the neighborhood of the magnetic null point on the separatrix. The chaos yields collisionless diffusion of electrons from the particle source (electron gun) towards the confinement region. Collisionless heating also occurs in the magnetic null region, which can be applied to produce a plasma. (author)
International Nuclear Information System (INIS)
SUBUDHI, M.; SULLIVAN, JR. E.J.
2002-01-01
THIS PAPER PRESENTS THE RESULTS OF AN AGING ASSESSMENT OF THE NUCLEAR POWER INDUSTRY RESPONSES TO NRC GENERIC LETTER 97-06 ON THE DEGRADATION OF STEAM GENERATOR INTERNALS EXPERIENCED AT ELECTRICITE DE FRANCE (EDF) PLANTS IN FRANCE AND AT A UNITED STATES PRESSURIZED WATER REACTOR (PWR). WESTINGHOUSE (W), COMBUSTION ENGINEERING (CE), AND BABCOCK AND WILCOX (BW) STEAM GENERATOR MODELS, CURRENTLY IN SERVICE AT U.S. NUCLEAR POWER PLANTS, POTENTIALLY COULD EXPERIENCE DEGRADATION SIMILAR TO THATFOUND AT EDF PLANTS AND THE U.S. PLANT. THE STEAM GENERATORS IN MANY OF THE U.S. PWRS HAVE BEEN REPLACED WITH STEAM GENERATORS WITH STEAM GENERATORS WITH IMPROVED DESIGNS AND MATERIALS. THESE REPLACEMENT STEAM GENERATORS HAVE BEEN MANUFACTURED IN THE U.S. AND ABROAD. DURING THIS ASSESSMENT, EACH OF THE THREE OWNERS GROUPS (W,CE, AND BW) IDENTIFIED FOR ITS STEAM GENERATOR, MODELS ALL THE POTENTIAL INTERNAL COMPONENTS THAT ARE VULNERABLE TO DEGRADATION WHILE IN SERVICE. EACH OWNERS GROUPDEVELOPED INSPEC TION AND MONITORING GUIDANCE AND RECOMMENDATIONS FOR ITS PARTICULAR STEAM GENERATOR MODELS. THE NUCLEAR ENERGY INSTITUTE INCORPORATED IN NEI 97-06 STEAM GENERATOR PROGRAM GUIDELINES, A REQUIREMENT TO MONITOR SECONDARY SIDE STEAM GENERATOR COMPONENTS IF THEIR FAILURE COULD PREVENT THE STEAM GENERATOR FROM FULFILLING ITS INTENDED SAFETY-RELATED FUNCTION. LICENSEES INDICATED THAT THEY IMPLEMENTED OR PLANNED TO IMPLEMENT, AS APPROPRIATE FOR THEIR STEAM GENERATORS, THEIR OWNERS GROUPRECOMMENDATIONS TO ADDRESS THE LONG-TERM EFFECTS OF THE POTENTIAL DEGRADATION MECHANISMS ASSOCIATED WITH THE STEAM GENERATOR INTERNALS
Nonideal magnetohydrodynamic instabilities and toroidal magnetic confinement
International Nuclear Information System (INIS)
Furth, H.P.
1985-05-01
The marked divergence of experimentally observed plasma instability phenomena from the predictions of ideal magnetohydrodynamics led in the early 1960s to the formulations of finite-resistivity stability theory. Beginning in the 1970s, advanced plasma diagnostics have served to establish a detailed correspondence between the predictions of the finite-resistivity theory and experimental plasma behavior - particularly in the case of the resistive kink mode and the tokamak plasma. Nonlinear resistive-kink phenomena have been found to govern the transport of magnetic flux and plasma energy in the reversed-field pinch. The other predicted finite-resistivity instability modes have been more difficult to identify directly and their implications for toroidal magnetic confinement are still unresolved
Magnetohydrodynamic Stability of a Toroidal Plasma's Separatrix
International Nuclear Information System (INIS)
Webster, A. J.; Gimblett, C. G.
2009-01-01
Large tokamaks capable of fusion power production such as ITER, should avoid large edge localized modes (ELMs), thought to be triggered by an ideal magnetohydrodynamic instability due to current at the plasma's separatrix boundary. Unlike analytical work in a cylindrical approximation, numerical work finds the modes are stable. The plasma's separatrix might stabilize modes, but makes analytical and numerical work difficult. We generalize a cylindrical model to toroidal separatrix geometry, finding one parameter Δ ' determines stability. The conformal transformation method is generalized to allow nonzero derivatives of a function on a boundary, and calculation of the equilibrium vacuum field allows Δ ' to be found analytically. As a boundary more closely approximates a separatrix, we find the energy principle indicates instability, but the growth rate asymptotes to zero
Three dimensional transport model for toroidal plasmas
International Nuclear Information System (INIS)
Copenhauer, C.
1980-12-01
A nonlinear MHD model, developed for three-dimensional toroidal geometries (asymmetric) and for high β (β approximately epsilon), is used as a basis for a three-dimensional transport model. Since inertia terms are needed in describing evolving magnetic islands, the model can calculate transport, both in the transient phase before nonlinear saturation of magnetic islands and afterwards on the resistive time scale. In the β approximately epsilon ordering, the plasma does not have sufficient energy to compress the parallel magnetic field, which allows the Alfven wave to be eliminated in the reduced nonlinear equations, and the model then follows the slower time scales. The resulting perpendicular and parallel plasma drift velocities can be identified with those of guiding center theory
Calculation of a toroidal labyrinth shields
International Nuclear Information System (INIS)
Sul'kin, A.G.
1979-01-01
Calculation of protective case with a toroidal labyrinth channel, being one of the main design elements of hose gamma-devices, is presented. The case provides relative isotropic distribution of radiation outside protection limits. The main geometric parameters of the channel are determined: r-radius of the channel hole, rho-bend radius of the channel axis, β-angle of the channel bend. General exposure dose rate of γ-radiation in the detection point at l distance (usually l=100 m during calculations), is also calculated. Differential current dose albedo values have been found for certain combinations of parameters of the labyrinth channel. It is considered for simplification of labyrinth channel calculations, that backward radiation scattering passes, without energy change and isotropically, due to which differential current albedo values of γ-radiation for any incidence angle may be determined from integral albedo current values by the empirie formula
Advanced toroidal facility vaccuum vessel stress analyses
International Nuclear Information System (INIS)
Hammonds, C.J.; Mayhall, J.A.
1987-01-01
The complex geometry of the Advance Toroidal Facility (ATF) vacuum vessel required special analysis techniques in investigating the structural behavior of the design. The response of a large-scale finite element model was found for transportation and operational loading. Several computer codes and systems, including the National Magnetic Fusion Energy Computer Center Cray machines, were implemented in accomplishing these analyses. The work combined complex methods that taxed the limits of both the codes and the computer systems involved. Using MSC/NASTRAN cyclic-symmetry solutions permitted using only 1/12 of the vessel geometry to mathematically analyze the entire vessel. This allowed the greater detail and accuracy demanded by the complex geometry of the vessel. Critical buckling-pressure analyses were performed with the same model. The development, results, and problems encountered in performing these analyses are described. 5 refs., 3 figs
The theory of toroidally confined plasmas
White, Roscoe B
2014-01-01
This graduate level textbook develops the theory of magnetically confined plasma, with the aim of bringing the reader to the level of current research in the field of thermonuclear fusion. It begins with the basic concepts of magnetic field description, plasma equilibria and stability, and goes on to derive the equations for guiding center particle motion in an equilibrium field. Topics include linear and nonlinear ideal and resistive modes and particle transport. It is of use to workers in the field of fusion both for its wide-ranging account of tokamak physics and as a kind of handbook or formulary. This edition has been extended in a number of ways. The material on mode-particle interactions has been reformulated and much new information added, including methodology for Monte Carlo implementation of mode destabilization. These results give explicit means of carrying out mode destabilization analysis, in particular for the dangerous fishbone mode. A new chapter on cyclotron motion in toroidal geometry has ...
Progress in toroidal confinement and fusion research
International Nuclear Information System (INIS)
Furth, H.P.
1987-10-01
During the past 30 years, the characteristic T/sub i/n tau/sub E/-value of toroidal-confinement experiments has advanced by more than seven orders of magnitude. Part of this advance has been due to an increase of gross machine parameters. Most of this advance has been due to an increase of gross machine parameters. Most of the advance is associated with improvements in the ''quality of plasma confinement.'' The combined evidence of spherator and tokamak research clarifies the role of magnetic-field geometry in determining confinement and points to the importance of shielding out plasma edge effects. A true physical understanding of anomalous transport remains to be achieved. 39 refs., 11 figs., 1 tab
Toroidal microinstability studies of high temperature tokamaks
International Nuclear Information System (INIS)
Rewoldt, G.; Tang, W.M.
1989-07-01
Results from comprehensive kinetic microinstability calculations are presented showing the effects of toroidicity on the ion temperature gradient mode and its relationship to the trapped-electron mode in high-temperature tokamak plasmas. The corresponding particle and energy fluxes have also been computed. It is found that, although drift-type microinstabilities persist over a wide range of values of the ion temperature gradient parameter η i ≡ (dlnT i /dr)/(dlnn i /dr), the characteristic features of the dominant mode are those of the η i -type instability when η i > η ic ∼1.2 to 1.4 and of the trapped-electron mode when η i ic . 16 refs., 7 figs
International Nuclear Information System (INIS)
Jantzi, B.
2001-01-01
In this presentation, the author discussed Ontario Power Generation's voluntary commitment to stabilize carbon dioxide equivalent emissions at 1990 levels. To do so, Ontario Power Generation is implementing a series of green energy initiatives, a corporate tree planting program, internal energy efficiency, and an emission reduction trading (ERT). The emphasis was placed on emission trading, where Ontario Power Generation is a leader in the field of greenhouse gas, nitrogen oxide and sulphur dioxide trading in Canada. The approach to trading adopted was explained, with the specifics provided for each of the different categories of emissions. Some examples further illustrated the process. The outlook for the future was outlined, with plans for the geological sequestration of carbon dioxide and enhanced oil recovery, low nitrogen oxide gasoline additive. The benefits of emission trading were discussed from the perspective of Ontario Power Generation and the environment, such as allowing real reductions in emissions in a cost effective manner, enhanced risk management, investments in emissions reductions. The author argued that emission reduction is the way of the future, representing the only way in which the greenhouse gas emissions reductions required to minimize global climate change will be accomplished
Resonant MHD modes with toroidal coupling
International Nuclear Information System (INIS)
Connor, J.W.; Hastie, R.J.; Taylor, J.B.
1990-07-01
This is part 2 of a study of resonant perturbations, such as resistive tearing and ballooning modes, in a torus. These are described by marginal ideal mhd equations in the regions between resonant surfaces; matching across these surfaces provides the dispersion relation. In part 1 we described how all the necessary information from the ideal mhd calculations could be represented by a so-called E-matrix. We also described the calculation of this E-matrix for tearing modes (even parity in perturbed magnetic field) in a large aspect ratio torus. There the toroidal modes comprise coupled cylinder tearing modes and the E-matrix is a generalization of the familiar Δ' quantity in a cylinder. In the present paper we discuss resistive ballooning, or twisting-modes, which have odd-parity in perturbed magnetic field. We show that, unlike the tearing modes, these odd-parity modes are instrinsically toroidal and are not directly related to the odd-parity modes in a cylinder. This is evident from the analysis of the high-n limit in ballooning-space, where a transition from a stable Δ' to an unstable Δ' occurs for the twisting mode when the ballooning effect exceeds the interchange effect, which can occur even at large aspect ratio (as in a tokamak). Analysis of the high-n limit in coordinate space, rather than ballooning space, clarifies this singular behaviour and indicates how one may define twisting-mode Δ'. It also yields a prescription for treating low-n twisting modes and a method for calculating an E-matrix for resistive ballooning modes in a large aspect ratio tokamak. The elements of this matrix are given in terms of cylindrical tearing mode solutions
Next Generation Safeguards Initiative Workshop on Enhanced Recruiting for International Safeguards
Energy Technology Data Exchange (ETDEWEB)
Pepper,S.E.; Rosenthal, M.D.; Fishbone, L.G.; Occhogrosso, D.M.; Lockwood, D.; Carroll, C.J.; Dreicer, M.; Wallace, R.; Fankhauser, J.
2009-07-12
Brookhaven National Laboratory (BNL) hosted a Workshop on Enhanced Recruiting for International Safeguards October 22 and 23, 2008. The workshop was sponsored by DOE/NA-243 under the Next Generation Safeguards Initiative (NGSI). Placing well-qualified Americans in sufficient number and in key safeguards positions within the International Atomic Energy Agency’s (IAEA’s) Department of Safeguards is an important U.S. non-proliferation objective. The goal of the NGSI Workshop on Enhanced Recruiting for International Safeguards was to improve U.S. efforts to recruit U.S. citizens for IAEA positions in the Department of Safeguards. The participants considered the specific challenges of recruiting professional staff, safeguards inspectors, and managers. BNL’s International Safeguards Project Office invited participants from the U.S. Department of Energy, the IAEA, U.S. national laboratories, private industry, academia, and professional societies who are either experts in international safeguards or who understand the challenges of recruiting for technical positions. A final report for the workshop will be finalized and distributed in early 2009. The main finding of the workshop was the need for an integrated recruitment plan to take into account pools of potential candidates, various government and private agency stakeholders, the needs of the IAEA, and the NGSI human capital development plan. There were numerous findings related to and recommendations for maximizing the placement of U.S. experts in IAEA Safeguards positions. The workshop participants offered many ideas for increasing the pool of candidates and increasing the placement rate. This paper will provide details on these findings and recommendations
Next Generation Safeguards Initiative Workshop on Enhanced Recruiting for International Safeguards
International Nuclear Information System (INIS)
Pepper, S.E.; Rosenthal, M.D.; Fishbone, L.G.; Occhogrosso, D.M.; Lockwood, D.; Carroll, C.J.; Dreicer, M.; Wallace, R.; Fankhauser, J.
2009-01-01
Brookhaven National Laboratory (BNL) hosted a Workshop on Enhanced Recruiting for International Safeguards October 22 and 23, 2008. The workshop was sponsored by DOE/NA-243 under the Next Generation Safeguards Initiative (NGSI). Placing well-qualified Americans in sufficient number and in key safeguards positions within the International Atomic Energy Agency's (IAEA's) Department of Safeguards is an important U.S. non-proliferation objective. The goal of the NGSI Workshop on Enhanced Recruiting for International Safeguards was to improve U.S. efforts to recruit U.S. citizens for IAEA positions in the Department of Safeguards. The participants considered the specific challenges of recruiting professional staff, safeguards inspectors, and managers. BNL's International Safeguards Project Office invited participants from the U.S. Department of Energy, the IAEA, U.S. national laboratories, private industry, academia, and professional societies who are either experts in international safeguards or who understand the challenges of recruiting for technical positions. A final report for the workshop will be finalized and distributed in early 2009. The main finding of the workshop was the need for an integrated recruitment plan to take into account pools of potential candidates, various government and private agency stakeholders, the needs of the IAEA, and the NGSI human capital development plan. There were numerous findings related to and recommendations for maximizing the placement of U.S. experts in IAEA Safeguards positions. The workshop participants offered many ideas for increasing the pool of candidates and increasing the placement rate. This paper will provide details on these findings and recommendations
Energy Technology Data Exchange (ETDEWEB)
Amber Shrivastava; Brian Williams; Ali S. Siahpush; Bruce Savage; John Crepeau
2014-06-01
There have been significant efforts by the heat transfer community to investigate the melting phenomenon of materials. These efforts have included the analytical development of equations to represent melting, numerical development of computer codes to assist in modeling the phenomena, and collection of experimental data. The understanding of the melting phenomenon has application in several areas of interest, for example, the melting of a Phase Change Material (PCM) used as a thermal storage medium as well as the melting of the fuel bundle in a nuclear power plant during an accident scenario. The objective of this research is two-fold. First a numerical investigation, using computational fluid dynamics (CFD), of melting with internal heat generation for a vertical cylindrical geometry is presented. Second, to the best of authors knowledge, there are very limited number of engineering experimental results available for the case of melting with Internal Heat Generation (IHG). An experiment was performed to produce such data using resistive, or Joule, heating as the IHG mechanism. The numerical results are compared against the experimental results and showed favorable correlation. Uncertainties in the numerical and experimental analysis are discussed. Based on the numerical and experimental analysis, recommendations are made for future work.
Development of the Next Generation Gas Trap for the Space Station Internal Thermal Control System
Leimkuehler, Thomas O.; Spelbring, Chris; Reeves, Daniel R.; Holt, James M.
2003-01-01
The current dual-membrane gas trap is designed to remove non-condensed gases (NCG) from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Design goals are to meet or exceed the current requirements to (1) include greater operating ranges and conditions, (2) eliminate reliance on the current hydrophilic tube fabrication process, and (3) increase operational life and tolerance to particulate and microbial growth fouling. In addition, the next generation gas trap will essentially be a 'dropin" design such that no modifications to the ITCS pump package assembly (PPA) will be required, and the implementation of the new design will not affect changes to the ITCS operational conditions, interfaces, or software. This paper will present the initial membrane module design and development work which has included (1) a trade study among several conceptual designs, (2) performance modeling of a hydrophobic-only design, and (3) small-scale development test data for the hydrophobic-only design. Testing has shown that the hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal.
Commissioning Test of ATLAS End-Cap Toroidal Magnets
Dudarev, A; Foussat, A; Benoit, P; Jeckel, M; Olyunin, A; Kopeykin, N; Stepanov, V; Deront, L; Olesen, G; Ponts, X; Ravat, S; Sbrissa, K; Barth, J; Bremer, J; Delruelle, J; Metselaar, J; Pengo, R; Pirotte, O; Buskop, J; Baynham, D E; Carr, F S; Holtom, E
2009-01-01
The system of superconducting toroids in the ATLAS experiment at CERN consists of three magnets. The Barrel Toroid was assembled and successfully tested in 2006. Next, two End-Cap Toroids have been tested on surface at 77 K and installed in the cavern, 100-m underground. The End Cap Toroids are based on Al stabilized Nb-Ti/Cu Rutherford cables, arranged in double pancake coils and conduction cooled at 4.6 K. The nominal current is 20.5 kA at 4.1 T peak field in the windings and the stored energy is 250 MJ per toroid. Prior to final testing of the entire ATLAS Toroidal system, each End Cap Toroid passed a commissioning test up to 21 kA to guarantee a reliable performance in the final assembly. In this paper the test results are described. It includes the stages of test preparation, isolation vacuum pumping and leak testing, cooling down, step-by-step charging to full current, training quenches and quench recovery. By fast discharges the quench detection and protection system was checked to demonstrate a safe e...
Energy Technology Data Exchange (ETDEWEB)
Goumiri, I. R. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Rowley, C. W. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Sabbagh, S. A. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Gates, D. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Boyer, M. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Andre, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kolemen, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Taira, K. [Florida State Univ, Dept Mech Engn, Tallahassee, FL USA.
2016-02-19
A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.
Rassinoux, Anne-Marie; Baud, Robert H; Rodrigues, Jean-Marie; Lovis, Christian; Geissbühler, Antoine
2007-01-01
The importance of clinical communication between providers, consumers and others, as well as the requisite for computer interoperability, strengthens the need for sharing common accepted terminologies. Under the directives of the World Health Organization (WHO), an approach is currently being conducted in Australia to adopt a standardized terminology for medical procedures that is intended to become an international reference. In order to achieve such a standard, a collaborative approach is adopted, in line with the successful experiment conducted for the development of the new French coding system CCAM. Different coding centres are involved in setting up a semantic representation of each term using a formal ontological structure expressed through a logic-based representation language. From this language-independent representation, multilingual natural language generation (NLG) is performed to produce noun phrases in various languages that are further compared for consistency with the original terms. Outcomes are presented for the assessment of the International Classification of Health Interventions (ICHI) and its translation into Portuguese. The initial results clearly emphasize the feasibility and cost-effectiveness of the proposed method for handling both a different classification and an additional language. NLG tools, based on ontology driven semantic representation, facilitate the discovery of ambiguous and inconsistent terms, and, as such, should be promoted for establishing coherent international terminologies.
Directory of Open Access Journals (Sweden)
Seçkin GÖNEN
2015-07-01
Full Text Available The world has become into a single market and geographical boundaries has disappeared due to globalization in international commerce caused by recent rapid technological advancements in our country and internationally. The significance of export incentive is arising day by day in order to countries having a voice in the field in addition to developing market shares and improving competition powers. Besides, considering many times that our country faced with a foreign trade deficit made encouraging exports compulsory. On this basis, Value Added Tax Law numbered 3065, export exemptions made available for exporters are appeared as a successful and efficient implementation. The aim of this study is to reveal applicability of VAT in healthcare sector generated by international business transactions. Through this aim, sample case analysis is used as a qualitative research method. As a result of the research conducted, exemptions of VAT are applied to goods available for sale through inward processing regime. During the importation of raw materials which are going to be used for processing of goods to be exported by suspension system, taxes are paid in importation of raw materials thus paid VAT amounts in regime context are received back from affiliated tax office.
Internal Short-Circuiting Phenomena In An Open-Cycle MHD Generator
Energy Technology Data Exchange (ETDEWEB)
Sasaki, Y.; Ishibashi, E. [Hitachi Research Laboratory, Hitachi-shi, Ibaraki-ken (Japan); Kasahara, T.; Kazawa, Y. [Hitachi Works, Hitachi Ltd., Hitachi-shi, Ibaraki-ken (Japan)
1968-11-15
The influence of internal electrical leakage due to circulating currents flowing through velocity boundary layers and due to metallic elements in insulating walls (peg walls) is experimentally investigated. For this purpose a combustion-driven MHD generator is utilized. The active part of the generator test section is 60 cm in length with a constant cross-section of 3 x 12 cm{sup 2}. At typical operating conditions about 70 g/s of diesel light oil is burned with oxygen-enriched air, resulting in a thermal input of 3 MW, a fluid velocity of 500 to 700 m/s and a gas temperature of 2700 to 2900 Degree-Sign K at the channel inlet. KOH is used as the seed material. The magnetic field can be raised up to 1.95 Teslas. In the range of lower magnetic fields (B < 0.8T) it is shown that an observed open-circuit voltage agrees well with the theoretical value OBh which is defined in a one-dimensional MHD model. In other words, the circulating currents scarcely affect the open-circuit voltage. The theoretical basis for this fact is obtained by the use of a simple model. Experimental results obtained in several runs using three sets of insulating walls show that thermal boundary layers at water-cooled metals are more conductive than expected and that the open- circuit voltage decreases because of leakage currents flowing through metal pegs, when the internal resistance of the generator is relatively large. Also, it is shown that an alumina coating is effective in reducing the leakage currents. (author)
Development of a toroidal shell-type shock absorber for an irradiated fuel shipping cask
International Nuclear Information System (INIS)
Sugita, Y.; Mochizuki, S.
1983-01-01
This study described the design method of a toroidal shell-type shock absorber and the dynamic responses of the cask body, the internal structure and water when this shock absorber was used. Conclusions are: the calculated results on the basis of the master curves of non-dimensionalized force-deflection relations by static compression tests show a close agreement with the experimental results; the internal structure moves together with the cask body in every position; and the maximum water pressure is larger by a factor of 1.2 than the static pressure multiplied by the maximum deceleration in every direction due to the low-frequency wave propagation
Kinetic energy principle and neoclassical toroidal torque in tokamaks
International Nuclear Information System (INIS)
Park, Jong-Kyu
2011-01-01
It is shown that when tokamaks are perturbed, the kinetic energy principle is closely related to the neoclassical toroidal torque by the action invariance of particles. Especially when tokamaks are perturbed from scalar pressure equilibria, the imaginary part of the potential energy in the kinetic energy principle is equivalent to the toroidal torque by the neoclassical toroidal viscosity. A unified description therefore should be made for both physics. It is also shown in this case that the potential energy operator can be self-adjoint and thus the stability calculation can be simplified by minimizing the potential energy.
Toroidal field effects on the stability of Heliotron E
International Nuclear Information System (INIS)
Carreras, B.A.; Garcia, L.; Lynch, V.E.
1986-02-01
The addition of a small toroidal field to the Heliotron E configuration improves the stability of the n = 1 mode and increases the value of the stability beta critical. Total stabilization of this mode can be achieved with added toroidal fields between 5 and 15% of the total field. In this situation, the plasma can have direct access to the second stability regime. For the Heliotron E configuration, the self-stabilization effect is due to the shear, not to the magnetic well. The toroidal field threshold value for stability depends strongly on the pressure profile and the plasma radius. 21 refs., 15 figs
1D equation for toroidal momentum transport in a tokamak
International Nuclear Information System (INIS)
Rozhansky, V A; Senichenkov, I Yu
2010-01-01
A 1D equation for toroidal momentum transport is derived for a given set of turbulent transport coefficients. The averaging is performed taking account of the poloidal variation of the toroidal fluxes and is based on the ambipolar condition of the zero net radial current through the flux surface. It is demonstrated that taking account of the Pfirsch-Schlueter fluxes leads to a torque in the toroidal direction which is proportional to the gradient of the ion temperature. This effect is new and has not been discussed before. The boundary condition at the separatrix, which is based on the results of the 2D simulations of the edge plasma, is formulated.
Deformation energy of a toroidal nucleus and plane fragmentation barriers
International Nuclear Information System (INIS)
Fauchard, C.; Royer, G.
1996-01-01
The path leading to pumpkin-like configurations and toroidal shapes is investigated using a one-parameter shape sequence. The deformation energy is determined within the analytical expressions obtained for the various shape-dependent functions and the generalized rotating liquid drop model taking into account the proximity energy and the temperature. With increasing mass and angular momentum, a potential well appears in the toroidal shape path. For the heaviest systems, the pocket is large and locally favourable with respect to the plane fragmentation barriers which might allow the formation of evanescent toroidal systems which would rapidly decay in several fragments to minimize the surface tension. (orig.)
Performance of a Folded-Strip Toroidally Wound Induction Machine
DEFF Research Database (Denmark)
Jensen, Bogi Bech; Jack, Alan G.; Atkinson, Glynn J.
2011-01-01
This paper presents the measured experimental results from a four-pole toroidally wound induction machine, where the stator is constructed as a pre-wound foldable strip. It shows that if the machine is axially restricted in length, the toroidally wound induction machine can have substantially...... shorter stator end-windings than conventionally wound induction machines, and hence that a toroidally wound induction machine can have lower losses and a higher efficiency. The paper also presents the employed construction method, which emphasizes manufacturability, and highlights the advantages...
Progress in gyrokinetic simulations of toroidal ITG turbulence
International Nuclear Information System (INIS)
Nevins, W.M.; Dimits, A.M.; Cohen, B.I.; Shumaker, D.E.
2001-01-01
The 3-D nonlinear toroidal gyrokinetic simulation code PG3EQ is used to study toroidal ion temperature gradient (ITG) driven turbulence - a key cause of the anomalous transport that limits tokamak plasma performance. Systematic studies of the dependence of ion thermal transport on various parameters and effects are presented, including dependence on E-vectorxB-vector and toroidal velocity shear, sensitivity to the force balance in simulations with radial temperature gradient variation, and the dependences on magnetic shear and ion temperature gradient. (author)
Laser-induced production of large carbon-based toroids
International Nuclear Information System (INIS)
Lyn, M. Elizabeth; He Jibao; Koplitz, Brent
2005-01-01
We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C 60 , 22% C 70 ). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2-0.3 μm with tubular diameters of ∼50-100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures
Electrostatic instabilities and turbulence in a toroidal magnetized plasma
International Nuclear Information System (INIS)
Poli, F. M.
2007-06-01
This Thesis aims at characterizing the linear properties of electrostatic drift instabilities arising in a toroidal plasma and the mechanisms leading to their development into turbulence. The experiments are performed on the TORoidal Plasma EXperiment (TORPEX) at CRPP-EPFL, Lausanne. The first part of the Thesis focuses on the identification of the nature of the instabilities observed in TORPEX, using a set of electrostatic probes, designed and built for this purpose. The global features of fluctuations, analyzed for different values of control parameters such as the magnetic field, the neutral gas pressure and the injected microwave power, are qualitatively similar in different experimental scenarios. The maximum of fluctuations is observed on the low field side, where the pressure gradient and the gradient of the magnetic field are co-linear, indicating that the curvature of the magnetic field lines has an important role in the destabilization of the waves. The power spectrum is dominated by electrostatic fluctuations with frequencies much lower than the ion cyclotron frequency. Taking advantage of the extended diagnostics coverage, the spectral properties of fluctuations are measured over the whole poloidal cross-section. Both drift and interchange instabilities develop and propagate on TORPEX, with the stability of both being affected by the curvature of the magnetic field. It is shown that modes of different nature are driven at separate locations over the plasma cross-section and that the wavenumber and frequency spectra, narrow at the location where the instabilities are generated, broaden during convection, suggesting an increase in the degree of turbulence. The transition from coherent to turbulent spectral features and the role of nonlinear coupling between modes in the development of turbulence are treated in the second part of this work. It is found that nonlinear mode-mode coupling is responsible for the redistribution of spectral energy from the
Jhang, Hogun; Kim, S. S.; Kwon, J. M.; Terzolo, L.; Kim, J. Y.; Diamond, P. H.
2010-11-01
It is accepted that the intrinsic rotation is generated via the residual stress, which is non-diffusive components of the turbulent Reynolds stress, without external momentum input. The physics leading to the onset of intrinsic rotation in L- and H- mode plasmas have been elucidated elsewhere. However, the physics responsible for the generation and transport of the intrinsic rotation and its relationship to the formation of internal transport barriers (ITBs) in reversed shear (RS) plasmas have not been explored in detail, which is the main subject in the present work. The revised version of the global gyrofluid code TRB is used for this study. It is found that the large intrinsic rotation (˜10-30% of the ion sound speed depending on ITB characteristics) is generated near the ITB region and propagates into the core. The intrinsic rotation increases linearly as the temperature gradient at ITB position increases, albeit not indefinitely. Key parameters related to the symmetry breaking, such as turbulent intensity and its gradient, the flux surface averaged parallel wavenumber are evaluated dynamically during the ITB formation. In particular, the role of reversed shear and the q-profile curvature is presented in relation to the symmetry breaking in RS plasmas.
Accelerated Electromechanical Modeling of a Distributed Internal Combustion Engine Generator Unit
Directory of Open Access Journals (Sweden)
Serhiy V. Bozhko
2012-07-01
Full Text Available Distributed generation with a combustion engine prime mover is still widely used to supply electric power in a variety of applications. These applications range from backup power supply systems and combined wind-diesel generation to providing power in places where grid connection is either technically impractical or financially uneconomic. Modelling of such systems as a whole is extremely difficult due to the long-time load profiles needed and the computational difficulty of including small time-constant electrical dynamics with large time-constant mechanical dynamics. This paper presents the development of accelerated, reduced-order models of a distributed internal combustions engine generator unit. Overall these models are shown to achieve a massive improvement in the computational time required for long-time simulations while also achieving an extremely high level of dynamic accuracy. It is demonstrated how these models are derived, used and verified against benchmark models created using established techniques. Throughout the paper the modelling set as a whole, including multi level detail, is presented, detailed and finally summarised into a crucial tool for general system investigation and multiple target optimisation.
Event generation for next to leading order chargino production at the international linear collider
Energy Technology Data Exchange (ETDEWEB)
Robens, T.
2006-10-15
At the International Linear Collider (ILC), parameters of supersymmetry (SUSY) can be determined with an experimental accuracy matching the precision of next-to-leading order (NLO) and higher-order theoretical predictions. Therefore, these contributions need to be included in the analysis of the parameters. We present a Monte-Carlo event generator for simulating chargino pair production at the ILC at next-to-leading order in the electroweak couplings. We consider two approaches of including photon radiation. A strict fixed-order approach allows for comparison and consistency checks with published semianalytic results in the literature. A version with soft- and hard-collinear resummation of photon radiation, which combines photon resummation with the inclusion of the NLO matrix element for the production process, avoids negative event weights, so the program can simulate physical (unweighted) event samples. Photons are explicitly generated throughout the range where they can be experimentally resolved. In addition, it includes further higher-order corrections unaccounted for by the fixed-order method. Inspecting the dependence on the cutoffs separating the soft and collinear regions, we evaluate the systematic errors due to soft and collinear approximations for NLO and higher-order contributions. In the resummation approach, the residual uncertainty can be brought down to the per-mil level, coinciding with the expected statistical uncertainty at the ILC. We closely investigate the two-photon phase space for the resummation method. We present results for cross sections and event generation for both approaches. (orig.)
Energy Technology Data Exchange (ETDEWEB)
de Felice, F; Nobili, L [Padua Univ. (Italy). Istituto di Fisica; Calvani, M [Padua univ. (Italy). Istituto di Astronomia
1976-03-01
The existence of extended Kerr metric sources of perfect fluid is taken as work-hypothesis to investigate the structure of the boundaries which derive from Boyer's surface condition. We find closed spheroidal configurations which hide an internal cavity as well as toroidal configurations; however, both the boundary of the internal cavity and the tori touch the ring singularity. We judge this feature non-physical and conclude that Boyer's condition is not sufficient to completely define a well behaved physical source.
Directory of Open Access Journals (Sweden)
Dmitry N. Bolotov
2013-01-01
Full Text Available The article deals with the main form of international payment - bank transfer and features when it is charging by banks correspondent fees for transit funds in their correspondent accounts. In order to optimize the cost of expenses for international money transfers there is a need to develop models and toolkit of automatic generation of the total amount of commissions in international interbank settlements. Accordingly, based on graph theory, approach to the construction of the model was developed.
International Nuclear Information System (INIS)
Zraick, Samir
1970-01-01
A macro-generator is a translator which is able to interpret and translate a programme written in a macro-language. After a first part presenting the main notions and proposing a brief description of the TAS-86 language, the second part of this research thesis reports the development of the macro-generator language, and notably presents the additional functionalities provided by the macro generator. The development is illustrated by logical flowcharts and programming listings
Equilibrium poloidal-field distributions in reversed-field-pinch toroidal discharges
International Nuclear Information System (INIS)
Baker, D.A.; Mann, L.W.; Schoenberg, K.F.
1983-01-01
A comparison between the approximate analytic formulae of Shafranov for equilibrium in axisymmetric toroidal systems and fully toroidal numerical solutions of the Grad-Shafranov equation for reversed-field-pinch (RFP) configurations is presented as a function of poloidal beta, internal plasma inductance, and aspect ratio. The Shafranov formula for the equilibrium poloidal-field distribution at the conducting shell that surrounds the plasma is accurate to within 5% for aspect ratios greater than 2, poloidal betas less than 50%, and for plasma current channels that exceed one third of the minor toroidal radius. The analytic description for the centre shift of the innermost flux surface that encloses the plasma current (the Shafranov shift) is accurate to within 15% for aspect ratios greater than 2 and poloidal betas below 50%, provided the shift does not exceed one tenth of the minor conducting boundary radius. The Shafranov formulae provide a convenient method for describing the gross equilibrium behaviour of an axisymmetric RFP discharge, as well as an effective tool for designing the poloidal-field systems of RFP experiments. (author)
Equilibrium poloidal field distributions in reversed-field-pinch toroidal discharges
International Nuclear Information System (INIS)
Baker, D.A.; Mann, L.W.; Schoenberg, K.F.
1982-04-01
A comparison between the analytic formulae of Shafranov for equilibrium in axisymmetric toroidal reversed field pinch (RFP) systems and fully toroidal numerical solutions of the Grad-Shafranov equation is presented as a function of poloidal beta, internal plasma inductance, and aspect ratio. The Shafranov formula for the equilibrium poloidal field distribution is accurate to within 5% for aspect ratios greater than 2, poloidal betas less than 50%, and for plasma current channels that exceed one-third of the minor toroidal radius. The analytic description for the center shift of the innermost flux surface that encloses the plasma current (the Shafranov shift) is accurate to within 15% for aspect ratios greater than 2 and poloidal betas below 50%, provided the shift does not exceed one-tenth of the minor conducting boundary radius. The behavior of the magnetic axis shift as a function of plasma parameters is included. The Shafranov formulae provide a convenient method for describing the equilibrium behavior of an RFP discharge. Examples illustrating the application of the analytic formulae to the Los Alamos ZT-40M RFP experiment are given
Plasma confinement of Nagoya high-beta toroidal-pinch experiments
International Nuclear Information System (INIS)
Hirano, K.; Kitagawa, S.; Wakatani, M.; Kita, Y.; Yamada, S.; Yamaguchi, S.; Sato, K.; Aizawa, T.; Osanai, Y.; Noda, N.
1977-01-01
Two different types of high-β toroidal pinch experiments, STP [1] and CCT [2,3], have been done to study the confinement of the plasma produced by a theta-pinch. The STP is an axisymmetric toroidal pinch of high-β tokamak type, while the CCT consists of multiply connected periodic toroidal traps. Internal current-carrying copper rings are essential to the CCT. Since both apparatuses use the same fast capacitor bank system, they produce rather similar plasma temperatures and densities. The observed laser scattering temperature and density is about 50 eV and 4x10 15 cm -3 , respectively, when the filling pressure is 5 mtorr. In the STP experiment, strong correlations are found between the βsub(p) value and the amplitude of m=2 mode. It has a minimum around the value of βsub(p) of 0.8. The disruptive instability is observed to expand the pinched plasma column without lowering the plasma temperature. Just before the disruption begins, the q value around the magnetic axis becomes far less than 1 and an increase of the amplitude of m=2 mode is seen. The CCT also shows rapid plasma expansion just before the magnetic field reaches its maximum. Then the trap is filled up with the plasma by this irreversible expansion and stable plasma confinement is achieved. The energy confinement time of the CCT is found to be about 35 μs. (author)
Wu, Cheng-Ju; Lin, Shih-Yu; Chou, Shang-Chin; Tsai, Chia-Yun; Yen, Jia-Yush
2014-01-01
This study designed a detachable and standardized toroidal test frame to measure the electromagnetic characteristic of toroidal laminated silicon steel specimens. The purpose of the design was to provide the measurements with standardized and controlled environment. The device also can withstand high temperatures (25-300°C) for short time period to allow high temperature tests. The accompanying driving circuit facilitates testing for high frequency (50-5,000 Hz) and high magnetic flux (0.2-1.8 T) conditions and produces both sinusoidal and nonsinusoidal test waveforms. The thickness of the stacked laminated silicon-steel sheets must be 30~31 mm, with an internal diameter of 72 mm and an outer diameter of 90 mm. With the standardized setup, it is possible to carry out tests for toroidal specimen in high temperature and high flux operation. The test results show that there is a tendency of increased iron loss under high temperature operation. The test results with various driving waveforms also provide references to the required consideration in engineering designs.
Overview, Progress, and Plans for the Compact Toroidal Hybrid Experiment
Hartwell, G. J.; Allen, N. R.; Ennis, D. A.; Hanson, J. D.; Howell, E. C.; Johnson, C. A.; Knowlton, S. F.; Kring, J. D.; Ma, X.; Maurer, D. A.; Ross, K. G.; Schmitt, J. C.; Traverso, P. J.; Williamson, E. N.
2017-10-01
The Compact Toroidal Hybrid (CTH) is an l = 2 , m = 5 torsatron/tokamak hybrid (R0 = 0.75 m, ap 0.2 m, and | B | disruption studies. The main goals of the CTH experiment are to study disruptive behavior as a function of applied 3D magnetic shaping, and to test and advance the V3FIT reconstruction code and NIMROD modeling of CTH. The disruptive density limit is observed to exceed the Greenwald limit as the vacuum transform is increased with no observed threshold for avoidance. Low-q operations (1.1 routine, with disruptions ceasing if the vacuum transform is raised above 0.07. Sawteeth are observed in CTH and have a similar phenomenology to tokamak sawteeth despite employing a 3D confining field. Application of vacuum transform has been demonstrated to reduce and eliminate the vertical drift of elongated discharges. Internal SXR diagnostics, in conjunction with external magnetics, extend the range of reconstruction accuracy into the plasma core. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.
Wall conditioning and leak localization in the advanced toroidal facility
International Nuclear Information System (INIS)
Langley, R.A.; Glowienka, J.C.; Mioduszewski, P.K.; Murakami, M.; Rayburn, T.F.; Simpkins, J.E.; Schwenterly, S.W.; Yarber, J.L.
1989-01-01
The Advanced Toroidal Facility (ATF) vacuum vessel and its internal components have been conditioned for plasma operation by baking, discharge cleaning with hydrogen and helium, and gettering with chromium and titanium. The plasma-facing surface of ATF consists mainly of stainless steel with some graphite; the outgassing area is dominated by the graphite because of its open porosity. Since this situation is somewhat different from that in other fusion plasma experiments, in which a single material dominates both the outgassing area and the plasma-facing area, different cleaning and conditioning techniques are required. The situation was aggravated by air leaks in the vacuum vessel, presumably resulting from baking and from vibration during plasma operation. The results of the various cleaning and conditioning techniques used are presented and compared on the basis of residual gas analysis and plasma performance. A technique for detecting leaks from the inside of the vacuum vessel is described; this technique was developed because access to the outside of the vessel is severely restricted by external components. 10 refs., 6 figs., 2 tabs
Wall conditioning and leak localization in the Advanced Toroidal Facility
International Nuclear Information System (INIS)
Langley, R.A.; Glowienka, J.C.; Mioduszewski, P.K.; Murakami, M.; Rayburn, T.F.; Simpkins, J.E.; Schwenterly, S.W.; Yarber, J.L.
1990-01-01
The Advanced Toroidal Facility (ATF) vacuum vessel and its internal components have been conditioned for plasma operation by baking, discharge cleaning with hydrogen and helium, and gettering with chromium and titanium. The plasma-facing surface of ATF consists mainly of stainless steel with some graphite; the outgassing area is dominated by the graphite because of its open porosity. Since this situation is somewhat different from that in other fusion plasma experiments, in which a single material dominates both the outgassing area and the plasma-facing area, different cleaning and conditioning techniques are required. The situation was aggravated by air leaks in the vacuum vessel, presumably resulting from baking and from vibration during plasma operation. The results of the various cleaning and conditioning techniques used are presented and compared on the basis of residual gas analysis and plasma performance. A technique for detecting leaks from the inside of the vacuum vessel is described. This technique was developed because access to the outside of the vessel is severely restricted by external components
Structural analyses of ITER toroidal field coils under fault conditions
International Nuclear Information System (INIS)
Jong, C.T.J.
1992-04-01
ITER (International Thermonuclear Experimental Reactor) is intended to be an experimental thermonuclear tokamak reactor testing the basic physics performance and technologies essential to future fusion reactors. The magnet system of ITER consists essentially of 4 sub-systems, i.e. toroidal field coils (TFCs), poloidal field coils (PFCs), power supplies, and cryogenic supplies. These subsystems do not contain significant radioactivity inventories, but the large energy inventory is a potential accident initiator. The aim of the structural analyses is to prevent accidents from propagating into vacuum vessel, tritium system and cooling system, which all contain significant amounts of radioactivity. As part of design process 3 conditions are defined for PF and TF coils, at which mechanical behaviour has to be analyzed in some detail, viz: normal operating conditions, upset conditions and fault conditions. This paper describes the work carried out by ECN to create a detailed finite element model of 16 TFCs as well as results of some fault condition analyses made with the model. Due to fault conditions, either electrical or mechanical, magnetic loading of TFCs becomes abnormal and further mechanical failure of parts of the overall structure might occur (e.g. failure of coil, gravitational supports, intercoil structure). The analyses performed consist of linear elastic stress analyses and electro-magneto-structural analyses (coupled field analyses). 8 refs.; 5 figs.; 5 tabs
System and method of operating toroidal magnetic confinement devices
Chance, M.S.; Jardin, S.C.; Stix, T.H.; Grimm, R.C.; Manickam, J.; Okabayashi, M.
1984-08-30
This invention pertains to methods and arrangements for attaining high beta values in plasma confinement devices. More specifically, this invention pertains to methods for accessing the second stability region of operation in toroidal magnetic confinement devices.
Influence of toroidal rotation on resistive tearing modes in tokamaks
International Nuclear Information System (INIS)
Wang, S.; Ma, Z. W.
2015-01-01
Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ R /τ V ≫ 1, where τ R and τ V represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ R /τ V ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large
Influence of toroidal rotation on resistive tearing modes in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Wang, S.; Ma, Z. W., E-mail: zwma@zju.edu.cn [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China)
2015-12-15
Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ{sub R}/τ{sub V} ≫ 1, where τ{sub R} and τ{sub V} represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ{sub R}/τ{sub V} ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large.
Confinement time exceeding one second for a toroidal electron plasma.
Marler, J P; Stoneking, M R
2008-04-18
Nearly steady-state electron plasmas are trapped in a toroidal magnetic field for the first time. We report the first results from a new toroidal electron plasma experiment, the Lawrence Non-neutral Torus II, in which electron densities on the order of 10(7) cm(-3) are trapped in a 270-degree toroidal arc (670 G toroidal magnetic field) by application of trapping potentials to segments of a conducting shell. The total charge inferred from measurements of the frequency of the m=1 diocotron mode is observed to decay on a 3 s time scale, a time scale that approaches the predicted limit due to magnetic pumping transport. Three seconds represents approximately equal to 10(5) periods of the lowest frequency plasma mode, indicating that nearly steady-state conditions are achieved.
Effect of toroidicity during lower hybrid mode conversion
International Nuclear Information System (INIS)
Riyopoulos, S.; Mahajan, S.
1985-11-01
The effect of toroidicity during lower hybrid mode conversion is examined by treating the wave propagation in an inhomogeneous medium as an eigenvalue problem for ω 2 (m,n),m,n poloidal and toroidal wave numbers. Since the frequency regime near ω 2 = ω/sub LH/ 2 is an accumulation point for the eigenvalue spectrum, the degenerate perturbation technique must be applied. The toroidal eigenmodes are constructed by a zeroth order superposition of monochromatic solutions with different poloidal dependence m, thus they generically exhibit a wide spectrum in k/sub parallel/ for given fixed ω 2 even for small inverse aspect ratio epsilon. In case that the average is in the neighborhood of k/sub min/, the minimum wave number for accessibility of the mode conversion regime, it is expected that excitation of toroidal modes rather than geometric optics will determine the wave coupling to the plasma
Toroidal and rotating bubble nuclei and the nuclear fragmentation
International Nuclear Information System (INIS)
Royer, G.; Fauchard, C.; Haddad, F.; Jouault, B.
1997-01-01
The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. Previously, a one-parameter shape sequence has been defined to describe the path leading to pumpkin-like configurations and toroidal shapes. New analytical expressions for the shape dependent functions have been obtained. The potential barriers standing in these exotic deformation paths are compared with the three-dimensional and plane-fragmentation barriers. Metastable bubble-like minima only appear at very high angular momentum and above the three dimensional fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localized below the plane-fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension
Calculation of toroidal fusion reactor blankets by Monte Carlo
International Nuclear Information System (INIS)
Macdonald, J.L.; Cashwell, E.D.; Everett, C.J.
1977-01-01
A brief description of the calculational method is given. The code calculates energy deposition in toroidal geometry, but is a continuous energy Monte Carlo code, treating the reaction cross sections as well as the angular scattering distributions in great detail
International Nuclear Information System (INIS)
Gadalla, M.A.
1992-01-01
This paper presents an overview analyses of the thermal instability or thermal viability of infinite cylindrical structures with non-linear and non-uniform internal heat generation. The structure may be subjected to different and combined boundary conditions. An analytical solution is obtained for the generalized problem in spite of the non-linearity and the non-homogeneity of the source term. Four case studies with different boundary conditions are presented. The analyses show that the critical parameter for thermal stability may be though of as an altitude of surface below which the cylindrical structure will be thermally stable and performance worthy. The results also show that the bounds of thermal stability of a cylindrical structure system (solid or hollow) is eminently determined by the boundary conditions to which the system is subjected and can significantly alter the life-span of the structure
Influence of an Internally-Generated QBO on Modeled Stratospheric Dynamics and Ozone
Hurwitz, M. M.; Newman, P. A.; Song, I. S.
2011-01-01
A GEOS V2 CCM simulation with an internally generated quasi-biennial oscillation (QBO) signal is compared to an otherwise identical simulation without a QBO. In a present-day climate, inclusion of the modeled QBO makes a significant difference to stratospheric dynamics and ozone throughout the year. The QBO enhances variability in the tropics, as expected, but also in the polar stratosphere in some seasons. The modeled QBO also affects the mean stratospheric climate. Because tropical zonal winds in the baseline simulation are generally easterly, there is a relative increase in zonal wind magnitudes in tropical lower and middle stratosphere in the QBO simulation. Extra-tropical differences between the QBO and 'no QBO' simulations thus reflect a bias toward the westerly phase of the QBO: a relative strengthening and poleward shifting the polar stratospheric jets, and a reduction in Arctic lower stratospheric ozone.
Fried, Itzhak; Mukamel, Roy; Kreiman, Gabriel
2011-01-01
Understanding how self-initiated behavior is encoded by neuronal circuits in the human brain remains elusive. We recorded the activity of 1019 neurons while twelve subjects performed self-initiated finger movement. We report progressive neuronal recruitment over ~1500 ms before subjects report making the decision to move. We observed progressive increase or decrease in neuronal firing rate, particularly in the supplementary motor area (SMA), as the reported time of decision was approached. A population of 256 SMA neurons is sufficient to predict in single trials the impending decision to move with accuracy greater than 80% already 700 ms prior to subjects’ awareness. Furthermore, we predict, with a precision of a few hundred ms, the actual time point of this voluntary decision to move. We implement a computational model whereby volition emerges once a change in internally generated firing rate of neuronal assemblies crosses a threshold. PMID:21315264
Toroidal high-spin isomers in the nucleus 304120
Staszczak, A.; Wong, Cheuk-Yin; Kosior, A.
2017-05-01
Background: Strongly deformed oblate superheavy nuclei form an intriguing region where the toroidal nuclear structures may bifurcate from the oblate spheroidal shape. The bifurcation may be facilitated when the nucleus is endowed with a large angular moment about the symmetry axis with I =Iz . The toroidal high-K isomeric states at their local energy minima can be theoretically predicted using the cranked self-consistent Skyrme-Hartree-Fock method. Purpose: We use the cranked Skyrme-Hartree-Fock method to predict the properties of the toroidal high-spin isomers in the superheavy nucleus 120304184. Method: Our method consists of three steps: First, we use the deformation-constrained Skyrme-Hartree-Fock-Bogoliubov approach to search for the nuclear density distributions with toroidal shapes. Next, using these toroidal distributions as starting configurations, we apply an additional cranking constraint of a large angular momentum I =Iz about the symmetry z axis and search for the energy minima of the system as a function of the deformation. In the last step, if a local energy minimum with I =Iz is found, we perform at this point the cranked symmetry- and deformation-unconstrained Skyrme-Hartree-Fock calculations to locate a stable toroidal high-spin isomeric state in free convergence. Results: We have theoretically located two toroidal high-spin isomeric states of 120304184 with an angular momentum I =Iz=81 ℏ (proton 2p-2h, neutron 4p-4h excitation) and I =Iz=208 ℏ (proton 5p-5h, neutron 8p-8h) at the quadrupole moment deformations Q20=-297.7 b and Q20=-300.8 b with energies 79.2 and 101.6 MeV above the spherical ground state, respectively. The nuclear density distributions of the toroidal high-spin isomers 120304184(Iz=81 ℏ and 208 ℏ ) have the maximum density close to the nuclear matter density, 0.16 fm-3, and a torus major to minor radius aspect ratio R /d =3.25 . Conclusions: We demonstrate that aligned angular momenta of Iz=81 ℏ and 208 ℏ arising from
Composite coils for toroidal field coils and method of using same
International Nuclear Information System (INIS)
Perkins, R. G.; Trujillo, S. M.
1985-01-01
A composite toroidal field (TF) generating means consisting of segmented magnetic coil windings is disclosed. Each coil winding of the TF generating means consists of a copper or copper alloy conductor segment and an aluminum or aluminum alloy conductor segment. The conductor segments are joined at a high strength, low electrical resistance joint and the joint may either be a mechanical or metallurgical one. The use of the aluminum or aluminum alloy conductor segments improves the neutron economy of the reactor with which the TF coil is associated and reduces TF coil nuclear heating and heating gradients, and activation in the TF coils
Polymer- and salt-induced toroids of hexagonal DNA.
Ubbink, J; Odijk, T
1995-01-01
A model is proposed for polymer- and salt-induced toroidal condensates of DNA, based on a recent theory of the undulation enhancement of the electrostatic interaction in the bulk hexagonal phase of semiflexible polyions. In a continuum approximation, the thermodynamic potential of a monomolecular toroid may be split up in bulk, surface, and curvature contributions. With the help of an approximate analytical minimization procedure, the optimal torus dimensions are calculated as a function of t...
Transport in the high temperature core of toroidal confinement systems
International Nuclear Information System (INIS)
Weiland, J.
1994-01-01
Recent theoretical and experimental results on confinement of hot plasmas in toroidal devices, particularly tokamaks, are discussed from general principal points of view and related to predictions from a toroidal drift wave model using a full transport matrix including off diagonal terms. A reactive fluid model corresponding to a two pole approximation of the kinetic response is used. This model has the ability to reproduce both adiabatic and isothermal limits of the perpendicular dynamics. 106 refs, 8 figs, 1 tab
International Nuclear Information System (INIS)
Bhasin, Vivek; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.
1993-01-01
In order to evaluate the possible release of radioactivity in extreme events, some postulated accidents are analysed and studied during the design stage of Steam Generator (SG). Among the various accidents postulated, the most important are Feed Water Line Break (FWLB) and Main Steam Line Break (MSLB). This report concerns with dynamic structural analysis of SG internals following FWLB/MSLB. The pressure/drag-force time histories considered were corresponding to the conditions leading to the accident of maximum potential. The SG internals were analysed using two approaches of structural dynamics. In first approach simplified DLF method was adopted. This method yields an upper bound values of stresses and deflection. In the second approach time history analysis by Mode Superposition Technique was adopted. This approach gives more realistic results. The structure was qualified as per ASME B and PV Code SecIII NB. It was concluded that in all the components except perforated flow distribution plate, the stress values based on elastic analysis are within the limits specified by ASME Code. In case of perforated flow distribution plate during the MSLB transient the stress values based on elastic analysis are higher than the ASME Code limits. Therefore, its limit load analysis had to be done. Finally, the collapse pressure evaluated using limit load analysis was shown to be within the limits of ASME B and PV Code SecIII Nb. (author). 31 refs., 94 figs., 16 tabs
Generation of Internal-Image Functional Aptamers of Okadaic Acid via Magnetic-Bead SELEX
Directory of Open Access Journals (Sweden)
Chao Lin
2015-12-01
Full Text Available Okadaic acid (OA is produced by Dinophysis and Prorocentrum dinoflagellates and primarily accumulates in bivalves, and this toxin has harmful effects on consumers and operators. In this work, we first report the use of aptamers as novel non-toxic probes capable of binding to a monoclonal antibody against OA (OA-mAb. Aptamers that mimic the OA toxin with high affinity and selectivity were generated by the magnetic bead-assisted systematic evolution of ligands by exponential enrichment (SELEX strategy. After 12 selection rounds, cloning, sequencing and enzyme-linked immunosorbent assay (ELISA analysis, four candidate aptamers (O24, O31, O39, O40 were selected that showed high affinity and specificity for OA-mAb. The affinity constants of O24, O31, O39 and O40 were 8.3 × 108 M−1, 1.47 × 109 M−1, 1.23 × 109 M−1 and 1.05 × 109 M−1, respectively. Indirect competitive ELISA was employed to determine the internal-image function of the aptamers. The results reveal that O31 has a similar competitive function as free OA toxin, whereas the other three aptamers did not bear the necessary internal-image function. Based on the derivation of the curvilinear equation for OA/O31, the equation that defined the relationship between the OA toxin content and O31 was Y = 2.185X − 1.78. The IC50 of O31 was 3.39 ng·mL−1, which was close to the value predicted by the OA ELISA (IC50 = 4.4 ng·mL−1; the IC10 was 0.33 ng·mL−1. The above data provides strong evidence that internal-image functional aptamers could be applicable as novel probes in a non-toxic assay.
International Nuclear Information System (INIS)
Vlases, G.C.; Pietrzyk, Z.A.
1984-11-01
Two older projects associated with very high energy density plasmas, specifically the High Density Field Reversed Configuration and the Liner Plasma Compression Experiment, have been completed. Attention has been turned to compact toroid experiments of more conventional density, and three experiments have been initiated. These include the Coaxial Slow Source Experiment, the Variable Length FRC Experiment, and Variable Angle CthetaP Experiment. In each case, the project was begun in order to provide basic plasma physics information on specific unresolved issues of progammatic importance to the national CT Program
Compact toroid injection into C-2U
Roche, Thomas; Gota, H.; Garate, E.; Asai, T.; Matsumoto, T.; Sekiguchi, J.; Putvinski, S.; Allfrey, I.; Beall, M.; Cordero, M.; Granstedt, E.; Kinley, J.; Morehouse, M.; Sheftman, D.; Valentine, T.; Waggoner, W.; the TAE Team
2015-11-01
Sustainment of an advanced neutral beam-driven FRC for a period in excess of 5 ms is the primary goal of the C-2U machine at Tri Alpha Energy. In addition, a criteria for long-term global sustainment of any magnetically confined fusion reactor is particle refueling. To this end, a magnetized coaxial plasma-gun has been developed. Compact toroids (CT) are to be injected perpendicular to the axial magnetic field of C-2U. To simulate this environment, an experimental test-stand has been constructed. A transverse magnetic field of B ~ 1 kG is established (comparable to the C-2U axial field) and CTs are fired across it. As a minimal requirement, the CT must have energy density greater than that of the magnetic field it is to penetrate, i.e., 1/2 ρv2 >=B2 / 2μ0 . This criteria is easily met and indeed the CTs traverse the test-stand field. A preliminary experiment on C-2U shows the CT also capable of penetrating into FRC plasmas and refueling is observed resulting in a 20 - 30% increase in total particle number per single-pulsed CT injection. Results from test-stand and C-2U experiments will be presented.
Chaotic magnetic field line in toroidal plasmas
International Nuclear Information System (INIS)
Hatori, Tadatsugu; Abe, Yoshihiko; Urata, Kazuhiro; Irie, Haruyuki.
1989-05-01
This is an introductory review of chaotic magnetic field line in plasmas, together with some new results, with emphasis on the long-time tail and the fractional Brownian motion of the magnetic field line. The chaotic magnetic field line in toroidal plasmas is a typical chaotic phenomena in the Hamiltonian dynamical systems. The onset of stochasticity induced by a major magnetic perturbation is thought to cause a macroscopic rapid phenomena called the current disruption in the tokamak discharges. Numerical simulations on the basis of magnetohydrodynamics reveal in fact the disruptive phenomena. Some dynamical models which include the area-preserving mapping such as the standard mapping, and the two-wave Hamiltonian system can model the stochastic magnetic field. Theoretical results with use of the functional integral representation are given regarding the long-time tail on the basis of the radial twist mapping. It is shown that application of renormalization group technique to chaotic orbit in the two-wave Hamiltonian system proves decay of the velocity autocorrelation function with the power law. Some new numerical results are presented which supports these theoretical results. (author)
''Turbulent Equipartition'' Theory of Toroidal Momentum Pinch
International Nuclear Information System (INIS)
Hahm, T.S.; Diamond, P.H.; Gurcan, O.D.; Rewaldt, G.
2008-01-01
The mode-independent part of magnetic curvature driven turbulent convective (TuroCo) pinch of the angular momentum density (Hahm et al., Phys. Plasmas 14,072302 (2007)) which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of 'magnetically weighted angular momentum density', nm i U # parallel# R/B 2 , and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustrated that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms which exist in a simpler geometry.
Experimental study of high beta toroidal plasmas
International Nuclear Information System (INIS)
Kellman, A.G.
1983-09-01
Experiments on the Wisconsin Levitated Toroidal Octupole have produced a wide range of stable high β plasmas with β significantly above single fluid MHD theory predictions. A stable β approx. 8% plasma, twice the fluid limit, is obtained with 5 rho/sub i/ approx. L/sub n/ and tau/sub β/ approx. = 6000 tau/sub Alfven/ = 600 μsec. The enhanced stability is explained with a kinetic treatment that includes the effect of finite ion gyroradius which couples the ballooning mode to an ion drift wave. In a more collisional, large gyroradius (2 rho/sub i/ approx. L/sub n/) regime, a stable β approx. 35% plasma is obtained with a decay time of 1000 Alfven times. Measurement of the equilibrium magnetic field in this regime indicates that the diamagnetic current density is five times smaller than predicted by ideal MHD, probably due to ion gyroviscosity. Particle transport is anomalous and ranges from agreement with the classical diffusion rate at the highest beta, lowest field plasma (B/sub P/ = 200 G), to thirteen times the classical rate in a β=11%, high field plasma (B/sub P/ = 860 G) where the level of enhancement increase with magnetic field. Fluctuations in density, electrostatic potential, and magnetic field have been studied in plasmas with β from 0.1% to 40%
The BNL toroidal volume H- source
International Nuclear Information System (INIS)
Alessi, J.G.; Prelec, K.
1991-01-01
The BNL toroidal volume H - ion source, in pulsed operation is now producing up to 35 mA with an electron to H - ratio of less than 5, and a ratio of less than 3 for currents up to 20 mA. This improvement came about by increasing the strength of the conical filter field. The source has also been operated steady state at low arc currents, where up to 6 mA of H - was extracted. The electron to H - ratio is 2--3 times larger for dc operation. For dc currents up to 5 mA, the arc power efficiency was 5 mA/kW. Pulsed performance with Ta and W filaments were very similar, except for the large gas pumping observed with the Ta filament. In dc operation, the Ta filament performed somewhat better than W. Extraction from 7 apertures having a total area of 1 cm 2 produced the same results as a single 1 cm 2 aperture. 5 refs., 4 figs
Effect of halo current and its toroidal asymmetry during disruptions in JT-60U
International Nuclear Information System (INIS)
Neyatani, Y.; Yoshino, R.; Ando, T.
1995-01-01
A poloidal halo current due to a vertical displacement event (VDE) is observed in experimentally simulated VDE discharges and density limit disruptions in the JT-60U tokamak. In the case of a clockwise I p and B T discharge, the halo current flows into the vacuum vessel from the inside separatrix and goes back to the plasma from the outside separatrix. A maximum halo current is produced by a change in the poloidal flux generated by plasma current decay. A toroidal asymmetry factor of 2.5 is estimated from the requirements of the fracture of the carbon-fiber composite tiles. The toroidal asymmetry is caused by the poloidal field (PF) that is produced by the toroidal field (TF) ripple, the deformation of the vacuum vessel, the setting error between the vacuum vessel and the TF and PF coils, the low-n mode during current quench, etc. To consider this asymmetry, in JT-60U, one must estimate the total halo current as nearly 26% of the plasma current just before a current quench. 25 refs., 10 figs
Formation of magnetic islands due to field perturbations in toroidal stellarator configurations
International Nuclear Information System (INIS)
Lee, D.K.; Harris, J.H.; Lee, G.S.
1990-06-01
An explicit formulation is developed to determine the width of a magnetic island separatrix generated by magnetic field perturbations in a general toroidal stellarator geometry. A conventional method is employed to recast the analysis in a magnetic flux coordinate system without using any simplifying approximations. The island width is seen to be proportional to the square root of the Fourier harmonic of B ρ /B ζ that is in resonance with the rational value of the rotational transform, where B ρ and B ζ are contravariant normal and toroidal components of the perturbed magnetic field, respectively. The procedure, which is based on a representation of three-dimensional flux surfaces by double Fourier series, allows rapid and fairly accurate calculation of the island widths in real vacuum field configurations, without the need to follow field lines through numerical integration of the field line equations. Numerical results of the island width obtained in the flux coordinate representation for the Advanced Toroidal Facility agree closely with those determined from Poincare puncture points obtained by following field lines. 22 refs., 5 tabs
An important step for the ATLAS toroid magnet
2000-01-01
The ATLAS experiment's prototype toroid coil arrives at CERN from the CEA laboratory in Saclay on 6 October. The world's largest superconducting toroid magnet is under construction for the ATLAS experiment. A nine-metre long fully functional prototype coil was delivered to CERN at the beginning of October and has since been undergoing tests in the West Area. Built mainly by companies in France and Italy under the supervision of engineers from the CEA-Saclay laboratory near Paris and Italy's INFN-LASA, the magnet is a crucial step forward in the construction of the ATLAS superconducting magnet system. Unlike any particle detector that has gone before, the ATLAS detector's magnet system consists of a large toroidal system enclosing a small central solenoid. The barrel part of the toroidal system will use eight toroid coils, each a massive 25 metres in length. These will dwarf the largest toroids in the world when ATLAS was designed, which measure about six metres. So the ATLAS collaboration decided to build a...
Turbulent transport of toroidal angular momentum in low flow gyrokinetics
International Nuclear Information System (INIS)
Parra, Felix I; Catto, Peter J
2010-01-01
We derive a self-consistent equation for the turbulent transport of toroidal angular momentum in tokamaks in the low flow ordering that only requires solving gyrokinetic Fokker-Planck and quasineutrality equations correct to second order in an expansion on the gyroradius over scale length. We also show that according to our orderings the long wavelength toroidal rotation and the long wavelength radial electric field satisfy the neoclassical relation that gives the toroidal rotation as a function of the radial electric field and the radial gradients of pressure and temperature. Thus, the radial electric field can be solved for once the toroidal rotation is calculated from the transport of toroidal angular momentum. Unfortunately, even though this methodology only requires a gyrokinetic model correct to second order in gyroradius over scale length, current gyrokinetic simulations are only valid to first order. To overcome this difficulty, we exploit the smallish ratio B p /B, where B is the total magnetic field and B p is its poloidal component. When B p /B is small, the usual first order gyrokinetic equation provides solutions that are accurate enough to employ for our expression for the transport of toroidal angular momentum. We show that current δf and full f simulations only need small corrections to achieve this accuracy. Full f simulations, however, are still unable to determine the long wavelength, radial electric field from the quasineutrality equation.
Investigation of intrinsic toroidal rotation scaling in KSTAR
Yoo, J. W.; Lee, S. G.; Ko, S. H.; Seol, J.; Lee, H. H.; Kim, J. H.
2017-07-01
The behaviors of an intrinsic toroidal rotation without any external momentum sources are investigated in KSTAR. In these experiments, pure ohmic discharges with a wide range of plasma parameters are carefully selected and analyzed to speculate an unrevealed origin of toroidal rotation excluding any unnecessary heating sources, magnetic perturbations, and strong magneto-hydrodynamic activities. The measured core toroidal rotation in KSTAR is mostly in the counter-current direction and its magnitude strongly depends on the ion temperature divided by plasma current (Ti/IP). Especially the core toroidal rotation in the steady-state is well fitted by Ti/IP scaling with a slope of ˜-23, and the possible explanation of the scaling is compared with various candidates. As a result, the calculated offset rotation could not explain the measured core toroidal rotation since KSTAR has an extremely low intrinsic error field. For the stability conditions for ion and electron turbulences, it is hard to determine a dominant turbulence mode in this study. In addition, the intrinsic toroidal rotation level in ITER is estimated based on the KSTAR scaling since the intrinsic rotation plays an important role in stabilizing resistive wall modes for future reference.
Toroidal visco-resistive magnetohydrodynamic steady states contain vortices
International Nuclear Information System (INIS)
Bates, J.W.; Montgomery, D.C.
1998-01-01
Poloidal velocity fields seem to be a fundamental feature of resistive toroidal magnetohydrodynamic (MHD) steady states. They are a consequence of force balance in toroidal geometry, do not require any kind of instability, and disappear in the open-quotes straight cylinderclose quotes (infinite aspect ratio) limit. If a current density j results from an axisymmetric toroidal electric field that is irrotational inside a torus, it leads to a magnetic field B such that ∇x(jxB) is nonvanishing, so that the Lorentz force cannot be balanced by the gradient of any scalar pressure in the equation of motion. In a steady state, finite poloidal velocity fields and toroidal vorticity must exist. Their calculation is difficult, but explicit solutions can be found in the limit of low Reynolds number. Here, existing calculations are generalized to the more realistic case of no-slip boundary conditions on the velocity field and a circular toroidal cross section. The results of this paper strongly suggest that discussions of confined steady states in toroidal MHD must include flows from the outset. copyright 1998 American Institute of Physics
Biomass gasification for electricity generation with internal combustion engines. Process efficiency
International Nuclear Information System (INIS)
Lesme-Jaén, René; Garcia Faure, Luis; Recio Recio, Angel; Oliva Ruiz, Luis; Pajarín Rodríguez, Juan; Revilla Suarez, Dennis
2015-01-01
Biomass is a renewable source of energy worldwide increased prospects for its potential and its lower environmental impact compared to fossil fuels. By processes and energy conversion technologies it is possible to obtain fuels in solid, liquid and gaseous form from any biomass. The biomass gasification is the thermal conversion thereof into a gas, which can be used for electricity production with the use of internal combustion engines with a certain level of efficiency, which depends on the characteristics of biomass and engines used. In this work the evaluation of thermal and overall efficiency of the gasification in Integrated Forestry Enterprise of Santiago de Cuba, designed to generate electricity from waste from the forest industry is presented. Is a downdraft gasifier reactor, COMBO-80 model and engine manufacturing Hindu (diesel) model Leyland modified to work with producer gas. The evaluation was carried out for different loads (electric power generated) engine from experimental measurements of flow and composition of the gas supplied to the engine. The results show that the motor operates with a thermal efficiency in the range of 20-32% with an overall efficiency between 12-25%. (full text)
Internally generated hippocampal sequences as a vantage point to probe future-oriented cognition.
Pezzulo, Giovanni; Kemere, Caleb; van der Meer, Matthijs A A
2017-05-01
Information processing in the rodent hippocampus is fundamentally shaped by internally generated sequences (IGSs), expressed during two different network states: theta sequences, which repeat and reset at the ∼8 Hz theta rhythm associated with active behavior, and punctate sharp wave-ripple (SWR) sequences associated with wakeful rest or slow-wave sleep. A potpourri of diverse functional roles has been proposed for these IGSs, resulting in a fragmented conceptual landscape. Here, we advance a unitary view of IGSs, proposing that they reflect an inferential process that samples a policy from the animal's generative model, supported by hippocampus-specific priors. The same inference affords different cognitive functions when the animal is in distinct dynamical modes, associated with specific functional networks. Theta sequences arise when inference is coupled to the animal's action-perception cycle, supporting online spatial decisions, predictive processing, and episode encoding. SWR sequences arise when the animal is decoupled from the action-perception cycle and may support offline cognitive processing, such as memory consolidation, the prospective simulation of spatial trajectories, and imagination. We discuss the empirical bases of this proposal in relation to rodent studies and highlight how the proposed computational principles can shed light on the mechanisms of future-oriented cognition in humans. © 2017 New York Academy of Sciences.
Development of Compact Toroid Injector for C-2 FRCs
Matsumoto, Tadafumi; Sekiguchi, Junichi; Asai, Tomohiko; Gota, Hiroshi; Garate, Eusebio; Allfrey, Ian; Valentine, Travis; Smith, Brett; Morehouse, Mark; TAE Team
2014-10-01
Collaborative research project with Tri Alpha Energy has been started and we have developed a new compact toroid (CT) injector for the C-2 device, mainly for fueling field-reversed configurations (FRCs). The CT is formed by a magnetized coaxial plasma-gun (MCPG), which consists of coaxial cylinder electrodes; a spheromak-like plasma is generated by discharge and pushed out from the gun by Lorentz force. The inner diameter of outer electrode is 83.1 mm and the outer diameter of inner electrode is 54.0 mm. The surface of the inner electrode is coated with tungsten in order to reduce impurities coming out from the electrode. The bias coil is mounted inside of the inner electrode. We have recently conducted test experiments and achieved a supersonic CT translation speed of up to ~100 km/s. Other typical plasma parameters are as follows: electron density ~ 5 × 1021 m-3, electron temperature ~ 40 eV, and the number of particles ~0.5-1.0 × 1019. The CT injector is now planned to be installed on C-2 and the first CT injection experiment will be conducted in the near future. The detailed MCPG design as well as the test experimental results will be presented.
Statistical properties of turbulence in a toroidal magnetized ECR plasma
International Nuclear Information System (INIS)
Yu Yi; Lu Ronghua; Wang Zhijiang; Wen Yizhi; Yu Changxuan; Wan Shude; Liu, Wandong
2008-01-01
The statistical analyses of fluctuation data measured by electrostatic-probe arrays clearly show that the self-organized criticality (SOC) avalanches are not the dominant behaviors in a toroidal ECR plasma in the SMT (Simple Magnetic Torus) mode of KT-5D device. The f -1 index region in the auto-correlation spectra of the floating potential V f and the ion saturation current I s , which is a fingerprint of a SOC system, ranges only in a narrow frequency band. By investigating the Hurst exponents at increasingly coarse grained time series, we find that at a time scale of τ>100 μs, there exists no or a very weak long-range correlation over two decades in τ. The difference between the PDFs of I s and V f clearly shows a more global nature of the latter. The transport flux induced by the turbulence suggests that the natural intermittency of turbulent transport maybe independent of the avalanche induced by near criticality. The drift instability is dominant in a SMT plasma generated by means of ECR discharges
Design study of toroidal magnets for tokamak experimental power reactors
International Nuclear Information System (INIS)
Stekly, Z.J.J.; Lucas, E.J.
1976-12-01
This report contains the results of a six-month study of superconducting toroidal field coils for a Tokamak Experimental Power Reactor to be built in the late 1980s. The designs are for 8 T and 12 T maximum magnetic field at the superconducting winding. At each field level two main concepts were generated; one in which each of the 16 coils comprising the system has an individual vacuum vessel and the other in which all the coils are contained in a single vacuum vessel. The coils have a D shape and have openings of 11.25 m x 7.5 m for the 8 T coils and 10.2 m x 6.8 m for the 12 T coils. All the designs utilize rectangular cabled conductor made from copper stabilized Niobium Titanium composite which operates at 4.2 K for the 8 T design and at 2.5 K for the 12 T design. Manufacturing procedures, processes and schedule estimates are also discussed
Structural analysis of the NET toroidal field coils and conductor
International Nuclear Information System (INIS)
Mitchell, N.; Collier, D.; Gori, R.
1989-01-01
The NET toroidal field coils will utilise A15-type superconductor at 4.2 K to generate fields up to 11.5 T. The superconductor strands themselves are sensitive to strain, which causes degradation of their current carrying capacity, and thus the detailed behaviour of the coil conductor must be analysied so that the strian can be minimised. This analysis must include the manufacturing processes of the conductor as well as the normal and abnormal loperational loads. The conductor will be insulated and bonded by glass fibre reinforced epoxy resin, with limited bonding shear strength, and the overall support of the complete coil system must be designed to reduce these shear stresses. The coils will be subjected to pulse loads form the poloidal field coils, and analysis of the slip between the various coil components, such as conductors and the coil case, giving rise to frictional heating and possible loss of superconducting properties is another important factor, which has been investigated by a number of stress analyses. The manufacturing, thermal and normal magnetic loads on the coils and the analysis leading to the proposed structural design are described. In addition to the normal operating conditions, there is a range of abnormal load conditions which could result from electrical or mechanical faults on the coils. The effect of these potential faults has been analysed and the coil design modified to prevent catastrophic structural failure. (author). 13 refs.; 8 figs.; 1 tab
Heat treatment trials for ITER toroidal field coils
International Nuclear Information System (INIS)
Matsui, Kunihiro; Hemmi, Tsutomu; Koizumi, Norikiyo; Nakajima, Hideo; Kimura, Satoshi; Nakamoto, Kazunari
2012-01-01
Cable-in-conduit (CIC) conductors using Nb 3 Sn strands are used in ITER toroidal fields (TF) coils. Heat treatment generates thermal strain in CIC conductors because of the difference in thermal expansion between the Nb 3 Sn strands and the stainless-steel jacket. The elongation/shrinkage of the TF conductor may make it impossible to insert a wound TF conductor into the groove of a radial plate. In addition, it is expected that the deformation of the winding due to heat treatment-based release of the residual force in the jacket may also make it impossible to insert the winding in the groove, and that correcting the winding geometry to allow insertion of the winding may influence the superconducting performance of the TF conductor. The authors performed several trials using heat treatment as the part of activities in Phase II of TF coil procurement aiming to resolve the above-mentioned technical issues, and evaluated the elongations of 0.064, 0.074 and 0.072% for the straight and curved conductors and 1/3-scale double-pancake (DP) winding, respectively. It was confirmed that correction if the deformed winding did not influence the superconducting performance of the conductor. (author)
International Nuclear Information System (INIS)
Niu, Zhiqiang; Diao, Hai; Yu, Shuhai; Jiao, Kui; Du, Qing; Shu, Gequn
2014-01-01
Highlights: • A 3-D model for exhaust-based thermoelectric waste heat recovery is developed. • Various heat, mass and electric transfer characteristics are elucidated. • Channel size needs to be moderate to balance heat transfer and pressure drop. • Bafflers need to be placed at all locations near all TEG modules. • Baffler angle needs to be sufficiently large, especially for downstream locations. - Abstract: Thermoelectric generator (TEG) has attracted considerable attention for the waste heat recovery of internal combustion engine. In this study, a 3-D numerical model for engine exhaust-based thermoelectric generator (ETEG) system is developed. By considering the detailed geometry of thermoelectric generator (TEG) and exhaust channel, the various transport phenomena are investigated, and design optimization suggestions are given. It is found that the exhaust channel size needs to be moderate to balance the heat transfer to TEG modules and pressure drop along channel. Increasing the number of exhaust channels may improve the performance, however, since more space and TEG modules are needed, the system size and cost need to be considered as well. Although only placing bafflers at the channel inlet could increase the heat transfer coefficient for the whole channel, the near wall temperature downstream might decrease significantly, leading to performance degradation of the TEG modules downstream. To ensure effective utilization of hot exhaust gas, the baffler angle needs to be sufficiently large, especially for the downstream locations. Since larger baffler angles increase the pressure drop significantly, it is suggested that variable baffler angles, with the angle increasing along the flow direction, might be a middle course for balancing the heat transfer and pressure drop. A single ETEG design may not be suitable to all the engine operating conditions, and making the number of exhaust channels and baffler angle adjustable according to different engine
Gu, Yongxian
The demand of portable power generation systems for both domestic and military applications has driven the advances of mesoscale internal combustion engine systems. This dissertation was devoted to the gasdynamic modeling and parametric study of the mesoscale internal combustion swing engine/generator systems. First, the system-level thermodynamic modeling for the swing engine/generator systems has been developed. The system performance as well as the potentials of both two- and four-stroke swing engine systems has been investigated based on this model. Then through parameterc studies, the parameters that have significant impacts on the system performance have been identified, among which, the burn time and spark advance time are the critical factors related to combustion process. It is found that the shorter burn time leads to higher system efficiency and power output and the optimal spark advance time is about half of the burn time. Secondly, the turbulent combustion modeling based on levelset method (G-equation) has been implemented into the commercial software FLUENT. Thereafter, the turbulent flame propagation in a generic mesoscale combustion chamber and realistic swing engine chambers has been studied. It is found that, in mesoscale combustion engines, the burn time is dominated by the mean turbulent kinetic energy in the chamber. It is also shown that in a generic mesoscale combustion chamber, the burn time depends on the longest distance between the initial ignition kernel to its walls and by changing the ignition and injection locations, the burn time can be reduced by a factor of two. Furthermore, the studies of turbulent flame propagation in real swing engine chambers show that the combustion can be enhanced through in-chamber turbulence augmentation and with higher engine frequency, the burn time is shorter, which indicates that the in-chamber turbulence can be induced by the motion of moving components as well as the intake gas jet flow. The burn time
ARTIST: An International Project Investigating Aerosol Retention in a Ruptured Steam Generator
International Nuclear Information System (INIS)
Guentay, S.; Dehbi, A.; Suckow, D.; Birchley, J.
2002-01-01
Steam generator tube ruptures (SGTR) with a concurrent stuck open safety relief valve are counted among the risk dominant accident sequences because of the potential for radioactive products to bypass the containment. Owing to the absence of relevant empirical data and the complexity of the geometry and controlling processes, the aerosol removal in the steam generator (SG) tubes and in the secondary side is not well understood. Therefore, little or no credit is usually taken for aerosol retention due to natural processes in the various components of a SG. To help reduce the uncertainties associated with fission product release following an SGTR sequence, the Paul Scherrer Institut has initiated an international experimental project to be performed in the ARTIST (AeRosol Trapping In a Steam generaTor) facility in the time period from 2002 to 2007. The ARTIST test section is a scaled model of a real SG, and is comprised of a 264-tube bundle with a maximum height of 3.8 m, as well as one full-size droplet separator and one full-size steam dryer. The ARTIST facility is capable of producing soluble and insoluble aerosols and entrain them at sonic gas flow rates (up to 0.25 kg/s, thus matching comparable values predicted by the codes. In addition, aerosols can be generated at prototypical concentrations (up to 5 g/m 3 ) and sizes (0.2-5 mm AMMD). State of the art instrumentation is used (Low-pressure impactors, photometers, on-line particle sizer, online droplet sizer, etc.). The ARTIST project will simulate the flow and retention of aerosol-borne fission products in the SG, and provide a unique database to support safety assessments and analytical models. The project is foreseen in seven phases: 1) Aerosol retention in the tube under dry secondary side conditions, 2) Aerosol retention in the near field close to break under dry conditions, 3) Aerosol retention in the bundle far field under dry conditions, 4) Aerosol retention in the separator and dryer under dry
International Nuclear Information System (INIS)
Van Sambeek, E.J.W.; Scheepers, M.J.J.
2004-06-01
In the SUSTELNET project criteria and guidelines have been developed that can create a level playing field in electricity markets between distributed generation (DG) and large scale power generation and will improve the network and market access of DG and electricity supply from renewable energy resources (RES). This report focuses on the European dimensions of DG regulation. The key findings of the SUSTELNET project are compared with the EU legislation, i.e. the current Electricity, Renewables and CHP Directives. Additional EU policy, regulation and initiatives are identified that can help Member States in developing future economically efficient and sustainable electricity supply systems
Results from the OECD report on international projections of electricity generating costs
International Nuclear Information System (INIS)
Paffenbarger, J.A.; Bertel, E.
1998-01-01
The International Energy Agency and Nuclear Energy Agency of the OECD have periodically undertaken a joint study on electricity generating costs in OECD Member countries and selected non-Member countries. This paper presents key results from the 1998 update of this study. Experts from 19 countries drawn from electric utility companies and government provided data on capital costs, operating and maintenance costs, and fuel costs from which levelized electricity generating costs (US cents/kWh) for baseload power plants were estimated in each country using a common set of economic assumptions. Light water nuclear power plants, pulverized coal plants, and natural gas-fired combined cycle gas turbines were the principal options evaluated. five and 10% discount rates, 40-year operating lifetime, and 75% annual load factor were the base assumptions, with sensitivity analyses on operating lifetime and load factor. Fuel costs and fuel escalation were provided individually by country, with a sensitivity case to evaluate costs assuming no real fuel price escalation over plant lifetimes. Of the three principal fuel/technology options, none is predominantly the cheapest option for all economic assumptions. However, fossil-fueled options are generally estimated to be the least expensive option. The study confirms that gas-fired combined cycles have improved their economic performance in most countries in recent years and are strong competitors to nuclear and coal-fired plants. Eleven out of the 18 countries with two or more options show gas-fired plants to be the cheapest option at 10% discount rate. Coal remains a strong competitor to gas when lower discount rates are used. Nuclear is the least expensive at both 5 and 10% discount rate in only two countries. Generally, with gas prices above 5 US$/GJ, nuclear plants constructed at overnight capital costs below 1 650 $/kWe have the potential to be competitive only at lower discount rates
Global Hybrid Simulations of Energetic Particle-driven Modes in Toroidal Plasmas
International Nuclear Information System (INIS)
Fu, G.Y.; Breslau, J.; Fredrickson, E.; Park, W.; Strauss, H.R.
2004-01-01
Global hybrid simulations of energetic particle-driven MHD modes have been carried out for tokamaks and spherical tokamaks using the hybrid code M3D. The numerical results for the National Spherical Tokamak Experiments (NSTX) show that Toroidal Alfven Eigenmodes are excited by beam ions with their frequencies consistent with the experimental observations. Nonlinear simulations indicate that the n=2 mode frequency chirps down as the mode moves out radially. For ITER, it is shown that the alpha-particle effects are strongly stabilizing for internal kink mode when central safety factor q(0) is sufficiently close to unity. However, the elongation of ITER plasma shape reduces the stabilization significantly
International Nuclear Information System (INIS)
Takase, Haruhiko; Senda, Ikuo
1999-01-01
A Toroidally Symmetric Plasma Simulation (TSPS) code has been developed for investigating the position and shape control on tokamak plasmas. The analyses of three-dimensional eddy currents on the conducting components around the plasma and the two-dimensional magneto-hydrodynamic (MHD) equilibrium are taken into account in this code. The code can analyze the plasma position and shape control during the minor disruption in which the deformation of plasma is not negligible. Using the ITER (International Thermonuclear Experimental Reactor) parameters, some examples of calculations are shown in this paper. (author)
International Nuclear Information System (INIS)
Takechi, M.; Matsunaga, G.; Takagi, S.
1999-09-01
Toroidal Alfven eigenmodes (TAE) destabilized by the pressure gradient of energetic alpha particles may expel the alpha particles before thermalization. TAE is important for tokamaks, and for helical systems (stellarators) as well. In CHS (compact helical system) TAE localized in the plasma core are destabilized when the plasma current is induced by co-injection of neutral beams. The observed TAE exhibits a ballooning nature. The internal structure of TAE was measured with a soft X-ray detector. The soft X-ray fluctuations level for TAE is too low to obtain the radial profiles of fluctuation intensities. (Tanaka, M.)
On the generation and evolution of internal solitary waves in the southern Red Sea
Guo, Daquan; Zhan, Peng; Kartadikaria, Aditya R.; Akylas, Triantaphyllos; Hoteit, Ibrahim
2015-01-01
the relatively weak tidal velocity in this area and their generation in the central of the domain, Da Silva suggested three possible mechanisms behind the generation of the waves, namely Resonance and disintegration of interfacial tides, Generation of interfacial
Converting existing Internal Combustion Generator (ICG) systems into HESs in standalone applications
International Nuclear Information System (INIS)
Perera, A.T.D.; Attalage, R.A.; Perera, K.K.C.K.; Dassanayake, V.P.C.
2013-01-01
Graphical abstract: - Highlights: • Obtained Pareto fronts of LEC, power supply reliability (PSR) and ICC/GHG emission. • Pareto surface was observed for smaller ICGs when considering LEC–PSR–GHG. • Shape of the LEC–PSR–ICC Pareto front gradually changes with ICG capacity. • Importance of multi-criterion decision-making after multi objective optimization. - Abstract: Expanding existing Internal Combustion Generator (ICG) systems by combining renewable energy sources is getting popular due to global concern on emission of green house gases (GHG) and increasing fossil fuel costs. Life cycle cost, initial capital cost (ICC), power supply reliability of the system, and GHG emission by ICG are factors to be considered in this process. Pareto front of Levelized Energy Cost (LEC)–Unmet Load Fraction (ULF)–GHG emission was taken in this study for four different expansion scenarios. Furthermore, Pareto front of ICC–LE–ULF was taken for three different expansion scenarios in order to analyze the impact of renewable energy integration. The results clearly depict that characteristics of the Pareto front varies with the scale of expansion and objectives taken for the optimization. A detailed analysis was conducted for a scale up problem with a 4 kVA ICG by using the Pareto fronts obtained
International Nuclear Information System (INIS)
Torabi, Mohsen; Zhang, Kaili
2014-01-01
This article investigates the classical entropy generation in cooled slabs. Two types of materials are assumed for the slab: homogeneous material and FGM (functionally graded material). For the homogeneous material, the thermal conductivity is assumed to be a linear function of temperature, while for the FGM slab the thermal conductivity is modeled to vary in accordance with the rule of mixtures. The boundary conditions are assumed to be convective and radiative concurrently, and the internal heat generation of the slab is a linear function of temperature. Using the DTM (differential transformation method) and resultant temperature fields from the DTM, the local and total entropy generation rates within slabs are derived. The effects of physically applicable parameters such as the thermal conductivity parameter for the homogenous slab, β, the thermal conductivity parameter for the FGM slab, γ, gradient index, j, internal heat generation parameter, Q, Biot number at the right side, Nc 2 , conduction–radiation parameter, Nr 2 , dimensionless convection sink temperature, δ, and dimensionless radiation sink temperature, η, on the local and total entropy generation rates are illustrated and explained. The results demonstrate that considering temperature- or coordinate-dependent thermal conductivity and radiation heat transfer at both sides of the slab have great effects on the entropy generation. - Highlights: • The paper investigates entropy generation in a slab due to heat generation and convective–radiative boundary conditions. • Both homogeneous material and FGM (functionally graded material) were considered. • The calculations are carried out using the differential transformation method which is a well-tested analytical technique
Toroidal Plasma Thruster for Interplanetary and Interstellar Space Flights
International Nuclear Information System (INIS)
Gorelenkov, N.N.; Zakharov, L.E.; Gorelenkova, M.V.
2001-01-01
This work involves a conceptual assessment for using the toroidal fusion reactor for deep space interplanetary and interstellar missions. Toroidal thermonuclear fusion reactors, such as tokamaks and stellarators, are unique for space propulsion, allowing for a design with the magnetic configuration localized inside toroidal magnetic field coils. Plasma energetic ions, including charged fusion products, can escape such a closed configuration at certain conditions, a result of the vertical drift in toroidal rippled magnetic field. Escaping particles can be used for direct propulsion (since toroidal drift is directed one way vertically) or to create and heat externally confined plasma, so that the latter can be used for propulsion. Deuterium-tritium fusion neutrons with an energy of 14.1 MeV also can be used for direct propulsion. A special design allows neutrons to escape the shield and the blanket of the tokamak. This provides a direct (partial) conversion of the fusion energy into the directed motion of the propellant. In contrast to other fusion concepts proposed for space propulsion, this concept utilizes the natural drift motion of charged particles out of the closed magnetic field configuration
Measurement of toroidal plasma current in RF heated helical plasmas
International Nuclear Information System (INIS)
Besshou, Sakae
1993-01-01
This report describes the measurement of toroidal plasma current by a semiflexible Rogowski coil in a helical vacuum chamber. A Rogowski coil measures the toroidal plasma current with a resolution of 0.1 kA, frequency range of up to 1 kHz and sensitivity of 6.5 x 10 -9 V · s/A. We measured the spontaneous toroidal plasma current (from -1.2 to +1.2 kA) under electron cyclotron resonance heating at 0.94 T toroidal field in the Heliotron-E device. We found that the measured direction of toroidal plasma current changes its sign as in the predicted behavior of a neoclassical diffusion-driven bootstrap current, depending on the horizontal position of the plasma column. We explain the observed plasma currents in terms of the compound phenomenon of an ohmic current and a neoclassical diffusion-driven current. The magnitude of the neoclassical current component is smaller than the value predicted by a collisionless neoclassical theory. (author)
Computer simulations of compact toroid formation and acceleration
International Nuclear Information System (INIS)
Peterkin, R.E. Jr.; Sovinec, C.R.
1990-01-01
Experiments to form, accelerate, and focus compact toroid plasmas will be performed on the 9.4 MJ SHIVA STAR fast capacitor bank at the Air Force Weapons Laboratory during the 1990. The MARAUDER (magnetically accelerated rings to achieve ultrahigh directed energy and radiation) program is a research effort to accelerate magnetized plasma rings with the masses between 0.1 and 1.0 mg to velocities above 10 8 cm/sec and energies above 1 MJ. Research on these high-velocity compact toroids may lead to development of very fast opening switches, high-power microwave sources, and an alternative path to inertial confinement fusion. Design of a compact toroid accelerator experiment on the SHIVA STAR capacitor bank is underway, and computer simulations with the 2 1/2-dimensional magnetohydrodynamics code, MACH2, have been performed to guide this endeavor. The compact toroids are produced in a magnetized coaxial plasma gun, and the acceleration will occur in a configuration similar to a coaxial railgun. Detailed calculations of formation and equilibration of a low beta magnetic force-free configuration (curl B = kB) have been performed with MACH2. In this paper, the authors discuss computer simulations of the focusing and acceleration of the toroid
Riley, Stephen
2016-01-01
This article draws attention to the constitutive requirements of intergenerational justice and exposes the limitations of regulative arguments based on international human rights law. Intergenerational justice demands constraining the regulative freedom of the international community, and it is
Mechanical stress calculations for toroidal field coils by the finite element method
International Nuclear Information System (INIS)
Soell, M.; Jandl, O.; Gorenflo, H.
1976-09-01
After discussing fundamental relationships of the finite element method, this report describes the calculation steps worked out for mechanical stress calculations in the case of magnetic forces and forces produced by thermal expansion or compression of toroidal field coils using the SOLID SAP IV computer program. The displacement and stress analysis are based on the 20-node isoparametric solid element. The calculation of the nodal forces produced by magnetic body forces are discussed in detail. The computer programs, which can be used generally for mesh generation and determination of the nodal forces, are published elsewhere. (orig.) [de
Current sustaining by RF travelling field in a collisional toroidal plasma
International Nuclear Information System (INIS)
Fukuda, Masaji; Matsuura, Kiyokata.
1977-06-01
The relation between the current generation by RF travelling field and the accompanied power absorption is studied in a collisional toroidal plasma, parameters being phase velocity and filling gas pressure or electron collision frequency. It is observed at a low magnetic field that the current is proportional to the plasma conductivity and an effective electromotive force, which is a new concept introduced on the basis of fluid model; the electromotive force is proportional to the absorbed RF power and inversely proportional to the plasma density and the phase velocity of the travelling field. (auth.)
HTMR: an experimental tokamak reactor with hybrid copper/superconductor toroidal field magnet
International Nuclear Information System (INIS)
Avanzini, P.G.; Raia, G.; Rosatelli, F.; Zampaglione, V.
1985-01-01
The feasibility of a hybrid configuration superconducting coils/copper coils for a next generation tokamak TF magnet has been investigated. On the basis of this hybrid solution, the conceptual design has been developed for a medium-high toroidal field tokamak reactor (HTMR). The results of this study show the possibility of designing a tokamak reactor with reduced size in comparison with other INTOR like devices, still gaining some margins in front of the uncertainties in the scaling laws for plasma physics parameters and retaining the presence of a blanket with a tritium breeding ratio of about 1
Current sustaining by RF travelling field in a collisional toroidal plasma
International Nuclear Information System (INIS)
Fukuda, Masaji; Matsuura, Kiyokata
1978-01-01
The relation between the current generated by RF travelling field and the absorbed power is studied in a collisional toroidal plasma, parameters being phase velocity and filling gap pressure or electron collision frequency. It is observed at a low magnetic field that the current is proportional to the plasma conductivity and an effective electromotive force, which is a new concept introduced on the basis of fluid model; the electromotive force is proportional to the absorbed RF power and inversely proportional to the plasma density and the phase velocity of the travelling field. (author)
Fast mega pixels video imaging of a toroidal plasma in KT5D device
International Nuclear Information System (INIS)
Xu Min; Wang Zhijiang; Lu Ronghua; Sun Xiang; Wen Yizhi; Yu Changxuan; Wan Shude; Liu Wandong; Wang Jun; Xiao Delong; Yu Yi; Zhu Zhenghua; Hu Linyin
2005-01-01
A direct imaging system, viewing visible light emission from plasmas tangentially or perpendicularly, has been set up on the KT5D toroidal device to monitor the real two-dimensional profiles of purely ECR generated plasmas. This system has a typical spatial resolution of 0.2 mm (1280x1024 pixels) when imaging the whole cross section. Interesting features of ECR plasmas have been found. Different from what classical theories have expected, a resonance layer with two or three bright spots, rather than an even vertical band, has been observed. In addition, images also indicate an intermittent splitting and drifting character of the plasmas
2011-01-01
Background Little is known about whether and how medical knowledge relates to interest in subspecialty fellowship training. The purpose of this study was to examine the relationships between residents' interest in subspecialty fellowship training and their knowledge of internal medicine (IM). Methods A questionnaire was emailed to 48 categorical postgraduate-year (PGY) two and three residents at a New York university-affiliated IM residency program in 2007 using the Survey Monkey online survey instrument. Overall and content area-specific percentile scores from the IM in-training examination (IM-ITE) for the same year was used to determine objective knowledge. Results Forty-five of 48 residents (response rate was 93.8%) completed the survey. Twenty-two (49%) were PG2 residents and 23(51%) were PGY3 residents. Sixty percent of respondents were male. Six (13%) residents were graduates of U.S. medical schools. Eight (18%) reported formal clinical training prior to starting internal medicine residency in the U.S. Of this latter group, 6 (75%) had training in IM and 6 (75) % reported a training length of 3 years or less. Thirty-seven of 45 (82%) residents had a subspecialty fellowship interest. Residents with a fellowship interest had a greater mean overall objective knowledge percentile score (56.44 vs. 31.67; p = 0.04) as well as greater mean percentile scores in all content areas of IM. The adjusted mean difference was statistically significant (p internal medicine residents. PMID:21281500
Structural analysis of TFTR toroidal field coil conceptual design
International Nuclear Information System (INIS)
Smith, R.A.
1975-10-01
The conceptual design evaluation of the V-shaped toroidal field coils on the Tokamak Fusion Test Reactor has been performed by detailed structural analysis with the finite element method. The innovation provided by this design and verified in this work is the capability to support toroidal field loads while simultaneously performing the function of twist restraint against the device axial torques resulting from the vertical field loads. The evaluations made for the conceptual design provide predictions for coil deflections and stresses. The results are available for the separate effects from toroidal fields, poloidal fields, and the thermal expansion of the coils as well as for the superposition of the primary loads and the primary plus thermal loads
Plasma flow in toroidal systems with a separatrix
International Nuclear Information System (INIS)
Gribkov, V.M.; Morozov, D.Kh.; Pogutse, O.P.
1984-01-01
A hydrodynamic plasma flow in toroidal systems is considered. Rlasma flow lines for various magnetic configurations are calculated. A particular attention is given to studying plasma flow in configurations with two magnetic a axes and a separatrix. The flow picture i the toroidal case is shown to qualita ity to penetrate through the separatrix - the latter becomes ''perforated''. Th he pictkre of these flows is calculated. The plasma diffusion coefficient with account for the separatrix is calculated and is shown not to turn into the infin nity in the toroidal case as well. The plasma flow is analytically considered in the model with distributed current as well as in the model with current conce entrated at the oroidal system axis. In the first case the existence of ''stagnant'' regions near the magnetic axis is established from which the plasma a does not flow out
A method for external measurement of toroidal equilibrium parameters
International Nuclear Information System (INIS)
Brunsell, P.; Hellblom, G.; Brynolf, J.
1992-01-01
A method has been developed for determining from external magnetic field measurements the horizontal shift, the vertical shift and the poloidal field asymmetry parameter (Λ) of a toroidal plasma in force equilibrium. The magnetic measurements consist of two toroidal differential flux loops, giving the average vertical magnetic field and the average radial magnetic field respectively, together with cosine-coils for obtaining the m=1 cosine harmonic of the external poloidal magnetic field component. The method is used to analyse the evolution of the toroidal equilibrium during reversed-field pinch discharges in the Extrap T1-U device. We find that good equilibrium control is needed for long plasma pulses. For non-optimized externally applied vertical fields, the diagnostic clearly shows a horizontal drift motion of the pinch resulting in earlier discharge termination. (au)
Bi-2223 HTS winding in toroidal configuration for SMES coil
International Nuclear Information System (INIS)
Kondratowicz-Kucewicz, B; Kozak, S; Kozak, J; Wojtasiewicz, G; Majka, M; Janowski, T
2010-01-01
Energy can be stored in the magnetic field of a coil. Superconducting Magnetic Energy Storage (SMES) is very promising as a power storage system for load levelling or power stabilizer. However, the strong electromagnetic force caused by high magnetic field and large coil current is a problem in SMES systems. A toroidal configuration would have a much less extensive external magnetic field and electromagnetic forces in winding. The paper describes the design of HTS winding for SMES coil in modular toroid configuration consist of seven Bi-2223 double-pancakes as well as numerical analysis of SMES magnet model using FLUX 3D package. As the results of analysis the paper presents the optimal coil configuration and the parameters such as radius of toroidal magnet, energy stored in magnet and magnetic field distribution.
Modal analysis of a stiffened toroidal shell sector
International Nuclear Information System (INIS)
Cerreta, R.; Di Pietro, E.; Pizzuto, A.
1987-01-01
This paper presents the results of the modal analysis of a sector of the toroidal vacuum vessel of a new experimental machine for research in the field of controlled thermonuclear fusion (FTU - Frascati Tokamak Upgrade). The vacuum vessel, one of the most critical components of the experimental device, consist of 12 stainless steel toroidal sectors, and it is designed to withstand pulsed electromagnetic loads during operation. Results of the modal analysis of the stiffened toroidal shell sector are compared and discussed with regard to the experimental data. Theoretical eigenvalues and eigenvectors have been predicted by means of ABAQUS finite element code. Experimental analysis has been carried out on a full scale model and natural frequencies have been measured. Satisfactory agreement between experimental and theoretical eigenvalues has been found
Structural analysis of the ITER Divertor toroidal rails
Energy Technology Data Exchange (ETDEWEB)
Viganò, F., E-mail: Fabio.Vigano@LTCalcoli.it [L.T. Calcoli SaS, Piazza Prinetti 26/B, 23807 Merate (Italy); Escourbiac, F.; Gicquel, S.; Komarov, V. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul lez Durance (France); Lucca, F. [L.T. Calcoli SaS, Piazza Prinetti 26/B, 23807 Merate (Italy); Merola, M. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul lez Durance (France); Ngnitewe, R. [L.T. Calcoli SaS, Piazza Prinetti 26/B, 23807 Merate (Italy)
2013-10-15
The Divertor is one of the most technically challenging components of the ITER machine, which has the main function of extracting the power conducted in the scrape-off layer while maintaining the plasma purity. There are 54 Divertor cassettes installed in the vacuum vessel (VV). Each cassette body (CB) is fastened on the inner and outer concentric Divertor toroidal rails. The comprehensive assessment (in accordance with the Structural Design Criteria for ITER In-vessel Components: ITER SDC-IC) of the Divertor toroidal rails has been performed during design activity based on performing of thermal and stress analyses at operating conditions of neutron stage of ITER operation. This paper outlines the engineering aspects of the ITER Divertor toroidal rails and focuses on some critical regions of the present design highlighted by the performed structural assessment. The structural assessment has been performed with help of using Finite Element (FE) Abaqus code and based on criteria given by ITER SDC-IC.
Toroidal Superheavy Nuclei in Skyrme-Hartree-Fock Approach
International Nuclear Information System (INIS)
Staszczak, A.; Wong, Cheuk-Yin
2009-01-01
Within the self-consistent constraint Skyrme-Hartree-Fock+BCS model (SHF+BCS), we found equilibrium toroidal nuclear density distributions in the region of superheavy elements. For nuclei with a sufficient oblate deformation (Q 20 < -200 b), it becomes energetically favorable to change the genus of nuclear surface from 0 to 1, i.e., to switch the shape from a biconcave disc to a torus. The energy of the toroidal (genus=1) SHF+BCS solution relative to the compact (genus=0) ground state energy is strongly dependent both on the atomic number Z and the mass number A. We discuss the region of Z and A where the toroidal SHF+BCS total energy begins to be a global minimum
Directory of Open Access Journals (Sweden)
Haidet Paul
2011-01-01
Full Text Available Abstract Background Little is known about whether and how medical knowledge relates to interest in subspecialty fellowship training. The purpose of this study was to examine the relationships between residents' interest in subspecialty fellowship training and their knowledge of internal medicine (IM. Methods A questionnaire was emailed to 48 categorical postgraduate-year (PGY two and three residents at a New York university-affiliated IM residency program in 2007 using the Survey Monkey online survey instrument. Overall and content area-specific percentile scores from the IM in-training examination (IM-ITE for the same year was used to determine objective knowledge. Results Forty-five of 48 residents (response rate was 93.8% completed the survey. Twenty-two (49% were PG2 residents and 23(51% were PGY3 residents. Sixty percent of respondents were male. Six (13% residents were graduates of U.S. medical schools. Eight (18% reported formal clinical training prior to starting internal medicine residency in the U.S. Of this latter group, 6 (75% had training in IM and 6 (75 % reported a training length of 3 years or less. Thirty-seven of 45 (82% residents had a subspecialty fellowship interest. Residents with a fellowship interest had a greater mean overall objective knowledge percentile score (56.44 vs. 31.67; p = 0.04 as well as greater mean percentile scores in all content areas of IM. The adjusted mean difference was statistically significant (p Conclusions More than half of surveyed residents indicated interest in pursuing a subspecialty fellowship. Fellowship interest appears positively associated with general medical knowledge in this study population. Further work is needed to explore motivation and study patterns among internal medicine residents.
Linear wave propagation in a hot axisymmetric toroidal plasma
International Nuclear Information System (INIS)
Jaun, A.
1995-03-01
Kinetic effects on the propagation of the Alfven wave are studied for the first time in a toroidal plasma relevant for experiments. This requires the resolution of a set of coupled partial differential equations whose coefficients depend locally on the plasma parameters. For this purpose, a numerical wave propagation code called PENN has been developed using either a bilinear or a bicubic Hermite finite element discretization. It solves Maxwell's equations in toroidal geometry, with a dielectric tensor operator that takes into account the linear response of the plasma. Two different models have been implemented and can be used comparatively to describe the same physical case: the first treats the plasma as resistive fluids and gives results which are in good agreement with toroidal fluid codes. The second is a kinetic model and takes into account the finite size of the Larmor radii; it has successfully been tested against a kinetic plasma model in cylindrical geometry. New results have been obtained when studying kinetic effects in toroidal geometry. Two different conversion mechanisms to the kinetic Alfven wave have been described: one occurs at toroidally coupled resonant surfaces and is the kinetic counterpart of the fluid models' resonance absorption. The other has no such correspondence and results directly from the toroidal coupling between the kinetic Alfven wave and the global wavefield. An analysis of a heating scenario suggests that it might be difficult to heat a plasma with Alfven waves up to temperatures that are relevant for a tokamak reactor. Kinetic effects are studied for three types of global Alfven modes (GAE, TAE, BAE) and a new class of kinetic eigenmodes is described which appear inside the fluid gap: it could be related to recent observations in the JET (Joint European Torus) tokamak. (author) 56 figs., 6 tabs., 58 refs
Linear wave propagation in a hot axisymmetric toroidal plasma
Energy Technology Data Exchange (ETDEWEB)
Jaun, A [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
1995-03-01
Kinetic effects on the propagation of the Alfven wave are studied for the first time in a toroidal plasma relevant for experiments. This requires the resolution of a set of coupled partial differential equations whose coefficients depend locally on the plasma parameters. For this purpose, a numerical wave propagation code called PENN has been developed using either a bilinear or a bicubic Hermite finite element discretization. It solves Maxwell`s equations in toroidal geometry, with a dielectric tensor operator that takes into account the linear response of the plasma. Two different models have been implemented and can be used comparatively to describe the same physical case: the first treats the plasma as resistive fluids and gives results which are in good agreement with toroidal fluid codes. The second is a kinetic model and takes into account the finite size of the Larmor radii; it has successfully been tested against a kinetic plasma model in cylindrical geometry. New results have been obtained when studying kinetic effects in toroidal geometry. Two different conversion mechanisms to the kinetic Alfven wave have been described: one occurs at toroidally coupled resonant surfaces and is the kinetic counterpart of the fluid models` resonance absorption. The other has no such correspondence and results directly from the toroidal coupling between the kinetic Alfven wave and the global wavefield. An analysis of a heating scenario suggests that it might be difficult to heat a plasma with Alfven waves up to temperatures that are relevant for a tokamak reactor. Kinetic effects are studied for three types of global Alfven modes (GAE, TAE, BAE) and a new class of kinetic eigenmodes is described which appear inside the fluid gap: it could be related to recent observations in the JET (Joint European Torus) tokamak. (author) 56 figs., 6 tabs., 58 refs.
Asymmetric flux generation and its relaxation in reversed field pinch
International Nuclear Information System (INIS)
Arimoto, H.; Masamune, S.; Nagata, A.
1985-02-01
The toroidally asymmetric flux enhancement [''dynamo effect''] and the axisymmetrization of the enhanced fluxes that follows in the setting up phase of Reversed Field Pinch are investigated on the STP-3[M] device. A rapid increase in the toroidal flux generated by the dynamo effect is first observed near the poloidal and toroidal current feeders. Then, this inhomogeneity of the flux propagates toroidally towards the plasma current. The axisymmetrization of the flux is attained just after the maximum of plasma current. The MHD activities decrease significantly after this axisymmetrization and the quiescent period is obtained. (author)
Achieve, Inc., 2010
2010-01-01
This appendix accompanies the report "Taking the Lead in Science Education: Forging Next-Generation Science Standards. International Science Benchmarking Report," a study conducted by Achieve to compare the science standards of 10 countries. This appendix includes the following: (1) PISA and TIMSS Assessment Rankings; (2) Courses and…
Papajohn, Dean
2006-01-01
While many institutions have utilized TOEFL scores for international admissions for many years, a speaking section has never before been a required part of TOEFL until the development of the iBT/Next Generation TOEFL. So institutions will need to determine how to set standards for the speaking section of TOEFL, also known as TOEFL Academic…
On the longitudinal coupling impedance of a toroidal beam tube
International Nuclear Information System (INIS)
Hahn, H.; Tepikian, S.
1990-01-01
In this paper, the longitudinal coupling impedance of a smooth toroidal beam tube is derived. By treating the torus as a slow-wave structure, the well-known method of describing the impedance in terms of cavity resonances can be used. A simple analytical expression for the coupling impedance of a toroidal beam tube with square cross section valid in the low-frequency limit is obtained. The results from the present study are compared with previously published solutions and qualitative differences are pointed out. 16 refs., 3 figs., 1 tab
Ion temperature gradient modes in toroidal helical systems
Energy Technology Data Exchange (ETDEWEB)
Kuroda, T. [Graduate University for Advanced Studies, Toki, Gifu (Japan); Sugama, H.; Kanno, R.; Okamoto, M.
2000-04-01
Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of {nabla}B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)
Ion temperature gradient modes in toroidal helical systems
International Nuclear Information System (INIS)
Kuroda, T.; Sugama, H.; Kanno, R.; Okamoto, M.
2000-04-01
Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of ∇B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)
Tokamak configuration analysis with the method of toroidal multipoles
International Nuclear Information System (INIS)
Micozzi, P.; Alladio, F.; Crisanti, F.; Marinucci, M.; Tanga, A.
1989-01-01
In the study of tokamak machines able to sustain plasmas of thermonuclear interest (JIT, IGNITOR, NET, CIT, ET), there is a strong quest for engineering optimization of the circuital components close to the plasma. We have developed a semianalytical axisymmetric MHD equilibrium code based on the technique of the poloidal ψ flux function expansion in toroidal harmonic series. This code is able to optimize the necessary currents in the poloidal circuits in order to sustain a plasma of fixed shape (also x-point configuration), toroidal current and poloidal β. (author) 4 refs., 4 figs
Neoclassical diffusion in toroidal three-cut magnetic field
International Nuclear Information System (INIS)
Nemov, V.V.; Shishkin, A.A.
1975-01-01
Quasi-classical diffusion is investigated in the regime of toroidal drift of 'bananas' in a three cut magnetic field. Unlike previous papers, it is supposed that the inhomogeneity of a helical magnetic field epsilonsub(k) is of the same order or less than that of the toroidal inhomogeneity epsilonsub(t). The case is considered when the efficient frequency of particle collisions exceeds that of the 'banana' precession around the magnetic axis. Expressions for diffusion flows and coefficients are obtained that transform into available ones at epsilonsub(h) > > epsilonsub(t) [ru
Effects of 3D magnetic perturbations on toroidal plasmas
International Nuclear Information System (INIS)
Callen, J.D.
2011-01-01
Small three-dimensional (3D) magnetic field perturbations have many interesting and possibly useful effects on tokamak and quasi-symmetric stellarator plasmas. Plasma transport equations that include these effects, most notably on diamagnetic-level toroidal plasma flows, have recently been developed. The 3D field perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (say 1-5) resonant (with field line pitch, q = m/n) and non-resonant fields, medium n (∼20, due to toroidal field ripple) and high n (due to microturbulence). Low n non-resonant fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal rotation throughout the plasma towards an offset rotation in the counter-current direction. Recent tokamak experiments have generally confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n toroidal field ripple produces similar effects plus possible ripple-trapping NTV effects and ion direct losses in the edge. A low n (e.g. n = 1) resonant field is mostly shielded by the toroidally rotating plasma at and inside the resonant (rational) surface. If it is large enough it can stop plasma rotation at the rational surface, facilitate magnetic reconnection there and lead to a growing stationary magnetic island (locked mode), which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components. In the plasma their lowest n (e.g. n = 1) externally resonant components can be amplified by kink-type plasma responses, particularly at high β. Low n plasma instabilities (e.g. resistive wall modes, neoclassical tearing modes) cause additional 3D magnetic perturbations in tokamak plasmas. Tearing modes in their nonlinear (Rutherford) regime bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can, if not shielded by plasma rotation effects, cause local magnetic
Compression of toroidal plasma by imploding plasma-liner
International Nuclear Information System (INIS)
Ikuta, Kazunari.
1979-07-01
A new concept of compressing a plasma in a closed magnetic configuration by a version of liner implosion flux compression technique is considered. The liner consists of a dense plasma cylinder, i.e. the plasma-liner. Maximum compression ratio of toroidal plasma is determined just by the initial density ratio of the toroidal plasma to the liner plasma because of the Rayleigh-Taylor instability. A start-up senario of plasma-liner is also proposed with a possible application of this concept to the creation of a burning plasma in reversed field configurations, i.e. burning plasma vortex. (author)
Development and verification of printed circuit board toroidal transformer model
DEFF Research Database (Denmark)
Pejtersen, Jens; Mønster, Jakob Døllner; Knott, Arnold
2013-01-01
An analytical model of an air core printed circuit board embedded toroidal transformer configuration is presented. The transformer has been developed for galvanic isolation of very high frequency switch-mode dc-dc power converter applications. The theoretical model is developed and verified...... by comparing calculated parameters with 3D finite element simulations and experimental measurement results. The developed transformer model shows good agreement with the simulated and measured results. The model can be used to predict the parameters of printed circuit board toroidal transformer configurations...
Compact toroid theory issues and approaches: a panel report
International Nuclear Information System (INIS)
1985-06-01
In the six years since the initiation of the compact toroid program by the Office of Fusion Energy, remarkable scientific advances have occurred on both field-reversed configurations (FRC) and spheromaks. This progress has been stimulated by a diverse experimental program with facilities at six laboratories, and by a small but nevertheless broad theoretical research effort encompassing more than a dozen institutions. The close coupling between theoretical and experimental programs has contributed immeasurably to this progress. This document offers guidance for future compact toroid theory by identifying and discussing the key physics issues. In most cases promising approaches to these issues are offered
Heat removal in INTOR via a toroidal limiter
International Nuclear Information System (INIS)
Mioduszewski, P.
1981-01-01
In the present paper the potential of removing about 100 MW of thermal plasma power via a toroidal limiter in INTOR is studied. The heat flux distributions on various limiter configurations are calculated and the thermal response of a graphite tile limiter is estimated on the base of a one-dimensional heat conduction approach. The evaporation rates which have to be expected for the given energy flux densities and radiation cooled graphite tiles are evaluated. According to the present understanding it should be possible to remove 100 MW power from the INTOR plasma via a radiation cooled toroidal limiter. (author)
Induction Motor with Switchable Number of Poles and Toroidal Winding
Directory of Open Access Journals (Sweden)
MUNTEANU, A.
2011-05-01
Full Text Available This paper presents a study of an induction motor provided with toroidal stator winding. The ring-type coils offer a higher versatility in obtaining a different number of pole pairs by means of delta/star and series/parallel connections respectively. As consequence, the developed torque can vary within large limits and the motor can be utilized for applications that require, for example, high load torque values for a short time. The study involves experimental tests and FEM simulation for an induction machine with three configurations of pole pairs. The conclusions attest the superiority of the toroidal winding for certain applications such as electric vehicles or lifting machines.
ALT-II toroidal belt limiter biasing experiments on TEXTOR
International Nuclear Information System (INIS)
Doerner, R.; Boedo, J.A.; Gray, D.S.
1991-01-01
Edge electric fields have been related to H-mode-like behaviour. The experiments reported here are an attempt to control the SOL profiles by electrostatic biasing of the full toroidal-belt limiter ALT-II. The specific goals are: influencing the edge particle flows, particle removal, power deposition and the global confinement. The ALT-II pump limiter is a full toroidal belt located at 45 o below the outer midplane and consisting of eight graphite covered blades which can be independently biased. Particle scoops located behind the limiter neutralize and direct the incoming plasma into the pumping ducts. (author) 5 refs., 3 figs
Electron diamagnetism and toroidal coupling of tearing modes
International Nuclear Information System (INIS)
Cowley, S.C.; Hastie, R.J.
1987-10-01
Using a simple model for the layer of the tearing mode, we demonstrate that toroidally coupled tearing modes with two rational surfaces are most unstable when the ω*'s of the electrons at the rational surfaces are equal. The onset of instability may then occur because of the tuning of ω* rather than the passage of Δ'-like quantities through zero. This mechanism for the onset of instability is sharp since the resonance is narrow. The effect of toroidal rotation is also discussed. 7 refs., 2 figs
Energy Technology Data Exchange (ETDEWEB)
Stallard, G.S.; Deschaine, R. [Black and Veatch (United States)
2008-05-15
The WEC Committee on the Performance of Generating Plant (PGP) has been collecting and analysing power plant performance statistics worldwide for more than 30 years and has produced regular reports, which include examples of advanced techniques and methods for improving power plant performance through benchmarking. A series of reports from the various working groups was issued in 2008. This reference presents the results of Working Group 1 (WG1). WG1's primary focus is to analyse the best ways to measure, evaluate, and apply power plant performance and availability data to promote plant performance improvements worldwide. The paper explores the specific work activities of 2004-2007 to extend traditional analysis and benchmarking frameworks. It is divided into two major topics: Overview of current electric supply industry issues/trends; and, Technical Methods/Tools to evaluate performance in today's ESI.
Computer numerically controlled (CNC) aspheric shaping with toroidal Wheels (Abstract Only)
Ketelsen, D.; Kittrell, W. C.; Kuhn, W. M.; Parks, R. E.; Lamb, George L.; Baker, Lynn
1987-01-01
Contouring with computer numerically controlled (CNC) machines can be accomplished with several different tool geometries and coordinated machine axes. To minimize the number of coordinated axes for nonsymmetric work to three, it is common practice to use a spherically shaped tool such as a ball-end mill. However, to minimize grooving due to the feed and ball radius, it is desirable to use a long ball radius, but there is clearly a practical limit to ball diameter with the spherical tool. We have found that the use of commercially available toroidal wheels permits long effective cutting radii, which in turn improve finish and minimize grooving for a set feed. In addition, toroidal wheels are easier than spherical wheels to center accurately. Cutting parameters are also easier to control because the feed rate past the tool does not change as the slope of the work changes. The drawback to the toroidal wheel is the more complex calculation of the tool path. Of course, once the algorithm is worked out, the tool path is as easily calculated as for a spherical tool. We have performed two experiments with the Large Optical Generator (LOG) that were ideally suited to three-axis contouring--surfaces that have no axis of rotational symmetry. By oscillating the cutting head horizontally or vertically (in addition to the motions required to generate the power of the surface) , and carefully coordinating those motions with table rotation, the mostly astigmatic departure for these surfaces is produced. The first experiment was a pair of reflector molds that together correct the spherical aberration of the Arecibo radio telescope. The larger of these was 5 m in diameter and had a 12 cm departure from the best-fit sphere. The second experiment was the generation of a purely astigmatic surface to demonstrate the feasibility of producing axially symmetric asphe.rics while mounted and rotated about any off-axis point. Measurements of the latter (the first experiment had relatively
Energy Technology Data Exchange (ETDEWEB)
Podesta, M; Fredrickson, E D; Gorelenkov, N N; LeBlanc, B P; Heidbrink, W W; Crocker, N A; Kubota, S
2010-08-19
The effects of a sheared toroidal rotation on the dynamics of bursting Toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40 557 (2000)]. The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of increased damping is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes.
International Nuclear Information System (INIS)
Podesta, M.; Bell, R.E.; Fredrickson, E.D.; Gorelenkov, N.N.; LeBlanc, B.P.; Heidbrink, W.W.; Crocker, N.A.; Kubota, S.; Yuh, H.
2010-01-01
The effects of a sheared toroidal rotation on the dynamics of bursting Toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) (M. Ono et al., Nucl. Fusion 40 557 (2000)). The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of increased damping is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes.
Transport and Dynamics in Toroidal Fusion Systems
International Nuclear Information System (INIS)
Sovinec, Carl
2016-01-01
The study entitled, 'Transport and Dynamics in Toroidal Fusion Systems,' (TDTFS) applied analytical theory and numerical computation to investigate topics of importance to confining plasma, the fourth state of matter, with magnetic fields. A central focus of the work is how non-thermal components of the ion particle distribution affect the 'sawtooth' collective oscillation in the core of the tokamak magnetic configuration. Previous experimental and analytical research had shown and described how the oscillation frequency decreases and amplitude increases, leading to 'monster' or 'giant' sawteeth, when the non-thermal component is increased by injecting particle beams or by exciting ions with imposed electromagnetic waves. The TDTFS study applied numerical computation to self-consistently simulate the interaction between macroscopic collective plasma dynamics and the non-thermal particles. The modeling used the NIMROD code [Sovinec, Glasser, Gianakon, et al., J. Comput. Phys. 195, 355 (2004)] with the energetic component represented by simulation particles [Kim, Parker, Sovinec, and the NIMROD Team, Comput. Phys. Commun. 164, 448 (2004)]. The computations found decreasing growth rates for the instability that drives the oscillations, but they were ultimately limited from achieving experimentally relevant parameters due to computational practicalities. Nonetheless, this effort provided valuable lessons for integrated simulation of macroscopic plasma dynamics. It also motivated an investigation of the applicability of fluid-based modeling to the ion temperature gradient instability, leading to the journal publication [Schnack, Cheng, Barnes, and Parker, Phys. Plasmas 20, 062106 (2013)]. Apart from the tokamak-specific topics, the TDTFS study also addressed topics in the basic physics of magnetized plasma and in the dynamics of the reversed-field pinch (RFP) configuration. The basic physics work contributed to a study of two
Transport and Dynamics in Toroidal Fusion Systems
Energy Technology Data Exchange (ETDEWEB)
Sovinec, Carl [Univ. of Wisconsin, Madison, WI (United States)
2016-09-07
The study entitled, "Transport and Dynamics in Toroidal Fusion Systems," (TDTFS) applied analytical theory and numerical computation to investigate topics of importance to confining plasma, the fourth state of matter, with magnetic fields. A central focus of the work is how non-thermal components of the ion particle distribution affect the "sawtooth" collective oscillation in the core of the tokamak magnetic configuration. Previous experimental and analytical research had shown and described how the oscillation frequency decreases and amplitude increases, leading to "monster" or "giant" sawteeth, when the non-thermal component is increased by injecting particle beams or by exciting ions with imposed electromagnetic waves. The TDTFS study applied numerical computation to self-consistently simulate the interaction between macroscopic collective plasma dynamics and the non-thermal particles. The modeling used the NIMROD code [Sovinec, Glasser, Gianakon, et al., J. Comput. Phys. 195, 355 (2004)] with the energetic component represented by simulation particles [Kim, Parker, Sovinec, and the NIMROD Team, Comput. Phys. Commun. 164, 448 (2004)]. The computations found decreasing growth rates for the instability that drives the oscillations, but they were ultimately limited from achieving experimentally relevant parameters due to computational practicalities. Nonetheless, this effort provided valuable lessons for integrated simulation of macroscopic plasma dynamics. It also motivated an investigation of the applicability of fluid-based modeling to the ion temperature gradient instability, leading to the journal publication [Schnack, Cheng, Barnes, and Parker, Phys. Plasmas 20, 062106 (2013)]. Apart from the tokamak-specific topics, the TDTFS study also addressed topics in the basic physics of magnetized plasma and in the dynamics of the reversed-field pinch (RFP) configuration. The basic physics work contributed to a study of two-fluid effects on interchange dynamics, where
International Nuclear Information System (INIS)
Aziz, A.; Bouaziz, M.N.
2011-01-01
Highlights: → Analytical solutions for a rectangular fin with temperature dependent heat generation and thermal conductivity. → Graphs give temperature distributions and fin efficiency. → Comparison of analytical and numerical solutions. → Method of least squares used for the analytical solutions. - Abstract: Approximate but highly accurate solutions for the temperature distribution, fin efficiency, and optimum fin parameter for a constant area longitudinal fin with temperature dependent internal heat generation and thermal conductivity are derived analytically. The method of least squares recently used by the authors is applied to treat the two nonlinearities, one associated with the temperature dependent internal heat generation and the other due to temperature dependent thermal conductivity. The solution is built from the classical solution for a fin with uniform internal heat generation and constant thermal conductivity. The results are presented graphically and compared with the direct numerical solutions. The analytical solutions retain their accuracy (within 1% of the numerical solution) even when there is a 60% increase in thermal conductivity and internal heat generation at the base temperature from their corresponding values at the sink temperature. The present solution is simple (involves hyperbolic functions only) compared with the fairly complex approximate solutions based on the homotopy perturbation method, variational iteration method, and the double series regular perturbation method and offers high accuracy. The simple analytical expressions for the temperature distribution, the fin efficiency and the optimum fin parameter are convenient for use by engineers dealing with the design and analysis of heat generating fins operating with a large temperature difference between the base and the environment.
International, private-public, multi-mission, next-generation lunar laser retroreflectors
Dell'Agnello, Simone
2017-04-01
Since the 1970s Lunar Laser Ranging (LLR) to the Apollo/Lunokhod Cube Corner Retroreflector (CCR) arrays supplied some of the best tests of General Relativity (GR): possible changes in the gravitational constant, weak and strong equivalence principle, gravitational self-energy (PPN parameter beta), geodetic precession, inverse-square force-law [1][2]. LLR has also provided significant information on the composition of the deep interior of the Moon [3]. LLR physics analysis also allows for constraints on extensions of GR (like spacetime torsion [4]) and on new gravitational physics that may explain the gravitational universe without Dark Matter and Dark Energy (like Non-Minimally Coupled gravity [5]). LLR is the only Apollo/Lunokhod experiment still in operation. In the 1970s LLR arrays contributed a negligible fraction of the ranging error budget. Since the capabilities of ground stations of the International Laser Ranging Service (in particular APOLLO in USA) improved by more than two orders of magnitude, now, because of the lunar librations, current CCR arrays dominate the error. With the US/Italy project LLRRA21/MoonLIGHT (Lunar Laser Ranging Retroreflector Array for the 21st century/Moon Laser Instrumentation for General relativity High accuracy Tests) UMD (Univ. of Maryland) and INFN (Italian National Institute for Nuclear Physics) developed a new-generation LLR payload made by a single, large CCR (100 mm diameter), unaffected by the effect of librations, that will improve the LLR accuracy by a factor of ten to one hundred. The performance of this 'big CCR' is being characterized at the SCF_Lab test facility at INFN-LNF, Frascati, Italy [6]. INFN also developed INRRI (INstrument for landing-Roving laser Retroreflector Investigations), a microreflector payload for the lunar surface to be laser-ranged by orbiters [7]. This will further extend the physics and lunar science reach of LLR. INRRI can also provide positioning services on the far side (it is proposed
Energy Technology Data Exchange (ETDEWEB)
Dreicer, M; Anzelon, G; Essner, J; Dougan, A; Doyle, J; Boyer, B; Hypes, P; Sokova, E; Wehling, F
2008-10-17
Key component of the Next Generation Safeguards Initiative (NGSI) launched by the National Nuclear Security Administration is the development of human capital to meet present and future challenges to the safeguards regime. An effective university-level education in safeguards and related disciplines is an essential element in a layered strategy to rebuild the safeguards human resource capacity. Two pilot programs at university level, involving 44 students, were initiated and implemented in spring-summer 2008 and linked to hands-on internships at LANL or LLNL. During the internships, students worked on specific safeguards-related projects with a designated Laboratory Mentor to provide broader exposure to nuclear materials management and information analytical techniques. The Safeguards and Nuclear Material Management pilot program was a collaboration between the Texas A&M University (TAMU), Los Alamos National Laboratory (LANL) and Lawrence Livermore National Laboratory (LLNL). It included a 16-lecture course held during a summer internship program. The instructors for the course were from LANL together with TAMU faculty and LLNL experts. The LANL-based course was shared with the students spending their internship at LLNL via video conference. A week-long table-top (or hands-on) exercise on was also conducted at LANL. The student population was a mix of 28 students from a 12 universities participating in a variety of summer internship programs held at LANL and LLNL. A large portion of the students were TAMU students participating in the NGSI pilot. The International Nuclear Safeguards Policy and Information Analysis pilot program was implemented at the Monterey Institute for International Studies (MIIS) in cooperation with LLNL. It included a two-week intensive course consisting of 20 lectures and two exercises. MIIS, LLNL, and speakers from other U.S. national laboratories (LANL, BNL) delivered lectures for the audience of 16 students. The majority of students were