Modeling the shape of a noncircular toroidal field coil
International Nuclear Information System (INIS)
Shah, V.N.; Marshall, N.H.
1983-01-01
Operating and transient forces acting on toroidal field coils may cause conductors and insulation to slide or break and may lead to quenching of the coil. Therefore, it is essential that each individual turn of the coil be modeled for detailed analysis of the coil structure. For this, a special purpose computer program is needed. As a first step in developing such a computer program, the authors present a finite element analysis of a turn of noncircular coil subjected to electromagnetic loading. A turn of superconducting coil is represented by a thin ring modeled by curved finite elements. Of the several curved beam elements reported in the literature, the strain element with two nodes, six degrees-of-freedom, and constant radius of curvature converges fastest for thin-deep arches whose geometrical characteristics are similar to those of a turn of toroidal field coil. They present an algorithm to model a noncircular ring using the number of strain elements satisfying the continuity of slopes at their nodes. This paper verifies the finite element model of a coil shape subjected to a toroidal magnetic field by solving three problems: circular and elliptic coils with the same inner and outer radii, a D-shaped coil, and a compound coil consisting of C- and D-shaped segments. The first problem shows that the resultant vertical force in the upper half of the coil is independent of coil shape. The remaining two problems calculate stresses that represent the constant tension in the D-shaped coil and in each segment of the compound coil. The results of the three problems compare well with the analytical results
International Nuclear Information System (INIS)
Kucinski, M.Y.; Caldas, I.L.
1986-08-01
Using the conventional toroidal coordinate system Laplace's equation for the magnetic scalar potential due to toroidal helical currents is solved. The potential is written as a sum of an infinite series of functions. Each partial sum represents the potential within some accuracy. The effect of the winding law is analysed in the case of small curvature. (Author) [pt
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
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
Hydraulics of the ITER toroidal field model coil cable-in-conduit conductors
International Nuclear Information System (INIS)
Nicollet, S.; Cloez, H.; Duchateau, J.L.; Serries, J.P.
1998-01-01
The test facility built at CEA-Cadarache OTHELLO (Operating Test facility for HELium LOop) is described, and pressure drop measurements all performed with nitrogen under pressure at room temperature are presented. Tests have been carried out on a 5 meters straight section of the superconducting cable of the Toroidal Field Model Coil. For the bundle region, a fit in form of the general formula proposed by Katheder agrees well with measurements. For the central hole, the friction factor measurements suggest a plateau at practical Reynolds numbers ranging near 10 6 , which could be modelled with the empirical Colebrook formula with an equivalent relative rugosity. This behaviour is quite different from what has been used up to now in the design criteria of ITER. (author)
ISX toroidal field coil design and analysis
International Nuclear Information System (INIS)
Hussung, R.O.; Lousteau, D.C.; Johnson, N.E.; Weed, R.A.
1975-01-01
Structural design and analysis aspects of the toroidal field coils for the Impurity Study Experiment (ISX) tokamak are discussed. The overall mechanical design of ISX is predicated on the ability to remove the upper segment of the toroidal field coils to allow access to the toroidal vacuum vessel. The high current, 120 kA, capability of the new 74 MW power supply, coupled with the modest field requirement of ISX, allows the use of room temperature copper coils. Seventy-two turns, grouped into 18 coils, generate a magnet field of 18 kG at the major radius of 90 cm. Finite element structural analysis codes were utilized to determine the distribution of stresses and deflections around a typical turn. Initial material distribution on a coil was sized using the two-dimensional program FEATS. The resulting coil design was then coupled to the center bucking and out-of-plane restraint systems utilizing the NASTRAN code. The boundary conditions for the analytical models used in the two programs were then iterated, reaching satisfactory agreement as to stress contours and location for the joints
Toroidal field coil torque structure
International Nuclear Information System (INIS)
Gaines, A.L.
1983-01-01
A torque structure is disclosed particularly suitable for utilization in a power reactor of the Tokamak-type, and operable therein for purposes of providing support for the toroidal field (TF) coils that comprise one of the major operating components of such a Tokamak power reactor. The subject torque structure takes the form of a frame structure that is operable to enable torque loads acting on the TF coils to be equilibrated as close to the area of force application as feasible. The aforesaid torque structure includes an intercoil structure composed of spacer wedges that are interposed between each adjacent pair of TF coils. The spacer wedges, in turn, consist of bearing plates positioned between the TF coils so as to be in contacting relation therewith and a number of cross plates that are cooperatively associated with the bearing plates so as to form therewith a rigid assembly. The intercoil structure is affixed to a segmented, membrane shell that surrounds, encloses and supports the TF coil frames. Access is had to the interior of the shell through an opening formed for this purpose in a reinforced portion of the shell. Eddy current losses are minimized by insulating the joints formed at the juncture of adjoining segments of the shell
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
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
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
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)
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
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)
Toroidal plasma response to external fields
International Nuclear Information System (INIS)
Storer, R.G.
1998-01-01
Toroidal plasmas respond to external driving fields in a way which is determined by the coupling of these fields to the spectrum of the plasma. We have extended the toroidal resistive magnetohydrodynamic spectral code, SPECTOR, to include the effects of external fields on tokamak-like plasmas. The code is capable of determining both the stable and unstable modes and also the response to helical applied fields with arbitrary mode structure. Resistivity changes the continuous regions of the ideal MHD spectrum into a set of discrete eigenvalues lying along lines in the complex frequency plane with a spacing which is related to the inverse of the square root of the magnetic Reynolds number. Results are presented which relate the spectral distribution to the plasma response as a function of frequency. (author)
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)
International Nuclear Information System (INIS)
Ulbricht, A.
2001-05-01
In the frame of a contract between the ITER (International Thermonuclear Experimental Reactor) Director and the European Home Team Director was concluded the extension of the TOSKA facility of the Forschungszentrum Karlsruhe as test bed for the ITER toroidal field model coil (TFMC), one of the 7 large research and development projects of the ITER EDA (Engineering Design Activity). The report describes the work and development, which were performed together with industry to extend the existing components and add new components. In this frame a new 2 kW refrigerator was added to the TOSKA facility including the cold lines to the Helium dewar in the TOSKA experimental area. The measuring and control system as well as data acquisition was renewed according to the state-of-the-art. Two power supplies (30 kA, 50 kA) were switched in parallel across an Al bus bar system and combined with an 80 kA dump circuit. For the test of the TFMC in the background field of the EURATOM LCT coil a new 20 kA power supply was taken into operation with the existing 20 kA discharge circuit. Two forced flow cooled 80 kA current leads for the TFMC were developed. The total lifting capacity for loads in the TOSKA building was increased by an ordered new 80 t crane with a suitable cross head (125 t lifting capacity +5 t net mass) to 130 t for assembling and installation of the test arrangement. Numerous pre-tests and development and adaptation work was required to make the components suitable for application. The 1.8 K test of the EURATOM LCT coil and the test of the W 7-X prototype coil count to these tests as overall pre-tests. (orig.)
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
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.)
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
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.)
Photoelastic analyses of stresses in toroidal magnetic field coils
International Nuclear Information System (INIS)
Pih, H.
1977-02-01
Several two-dimensional photoelastic stress analyses were made on models of circular and oval toroidal magnetic field coils for fusion reactors. The circumferential variation of each coil's in-plane magnetic force was simulated by applying different pressures to 16 segmented regions of the inner surface of the models. One special loading fixture was used for the model of each shape and size. Birefringence and isoclinic angles were measured in a transmission polariscope at selected points on the loaded model. Boundary stresses in the cases of known boundary conditions were determined directly from the isochromatics. Separate principal stresses were calculated using the combination of photoelastic information and isopachic data obtained by the electrical analogy method from the solution of Laplace's equation. Comparisons were made between experimental results and those computed using the finite element method. The stress distribution between theoretical and experimental agrees very well, although the finite element method yielded slightly higher stresses than the photoelastic method; further work is needed to resolve this difference. In this investigation several variations of coil geometry and methods of support were evaluated. Based on experimental results, optimum structural designs of toroidal field coils were recommended
Instability of Toroidal Magnetic Field in Jets and Plerions
Begelman, Mitchell C.
1998-01-01
Astrophysical jets and pulsar-fed supernova remnants (plerions) are expected to develop highly organized magnetic structures dominated by concentric loops of toroidal field, Bφ. It has been argued that such structures could explain the polarization properties of some jets and contribute to their lateral confinement through magnetic tension forces. A concentric toroidal field geometry is also central to the Rees-Gunn model for the Crab Nebula, the archetypal plerion, and leads to the deduction that the Crab pulsar's wind must have a weak magnetic field. Yet this kind of equilibrium between magnetic and gas pressure forces, the ``equilibrium Z-pinch'' of the controlled fusion literature, is well known to be susceptible to disruptive localized instabilities, even when the magnetic field is weak and/or boundary conditions (e.g., a dense external medium) slow or suppress global modes. Thus, the magnetic field structures imputed to the interiors of jets and plerions are unlikely to persist for very long. To determine the growth rates of Z-pinch instabilities under astrophysical conditions, I derive a dispersion relation that is valid for the relativistic fluids of which jets and plerions may be composed, in the ideal magnetohydrodynamics (MHD) limit. The dominant instabilities are kink (m = 1) and pinch (m = 0) modes. The former generally dominate, destroying the concentric field structure and probably driving the system toward a more chaotic state in which the mean field strength is independent of radius (and in which resistive dissipation of the field may be enhanced). I estimate the timescales over which the field structure is likely to be rearranged and relate these to distances along relativistic jets and radii from the central pulsar in a plerion. I conclude that the central tenet of the Rees-Gunn model for the Crab Nebula, the existence of a concentric toroidal field well outside the pulsar wind's termination shock, is physically unrealistic. With this assumption
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
Protection of toroidal field coils using multiple circuits
International Nuclear Information System (INIS)
Thome, R.J.; Langton, W.G.; Mann, W.R.; Pillsbury, R.D.; Tarrh, J.M.
1983-01-01
The protection of toroidal field (TF) coils using multiple circuits is described. The discharge of a single-circuit TF system is given for purposes of definition. Two-circuit TF systems are analyzed and the results presented analytically and graphically. Induced currents, maximum discharge voltages, and discharge time constants are compared to the single-circuit system. Three-circuit TF systems are analyzed. In addition to induced currents, maximum discharge voltages, and time constants, several different discharge scenarios are included. The impacts of having discharge rates versus final maximum coil temperatures as requirements are examined. The out-of-plane forces which occur in the three-circuit system are analyzed using an approximate model. The analysis of multiplecircuit TF systems is briefly described and results for a Toroidal Fusion Core Experiment (TFCX) scale device are given based on computer analysis. The advantages and disadvantages of using multiple-circuit systems are summarized and discussed. The primary disadvantages of multiple circuits are the increased circuit complexity and potential for out-of-plane forces. These are offset by the substantial reduction in maximum discharge voltages, as well as other design options which become available when using multiple circuits
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
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
International Nuclear Information System (INIS)
Arrayás, Manuel; Trueba, José L
2015-01-01
An electromagnetic knot is an electromagnetic field in vacuum in which the magnetic lines and the electric lines coincide with the level curves of a pair of complex scalar fields ϕ and θ (see equations (A.1), (A.2)). When electromagnetism is expressed in terms of electromagnetic knots, it includes mechanisms for the topological quantization of the electromagnetic helicity, the electric charge, the electromagnetic energy inside a cavity and the magnetic flux through a superconducting ring. In the case of electromagnetic helicity, its topological quantization depends on the linking number of the field lines, both electric and magnetic. Consequently, to find solutions of the electromagnetic knot equations with nontrivial topology of the field lines has important physical consequences. We study a new class of solutions of Maxwell's equations in vacuum Arrayás and Trueba (2011 arXiv:1106.1122) obtained from complex scalar fields that can be interpreted as maps S 3 →S 2 , in which the topology of the field lines is that of the whole torus-knot set. Thus this class of solutions is built as electromagnetic knots at initial time. We study some properties of those fields and consider if detection based on the energy and momentum observables is possible. (paper)
Energy Technology Data Exchange (ETDEWEB)
Gilman, Peter A., E-mail: gilman@ucar.edu [High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Green, Boulder, CO 80307-3000 (United States)
2017-06-20
We present results from an MHD model for baroclinic instability in the solar tachocline that includes rotation, effective gravity, and toroidal field that vary continuously with height. We solve the perturbation equations using a shooting method. Without toroidal fields but with an effective gravity declining linearly from a maximum at the bottom to much smaller values at the top, we find instability at all latitudes except at the poles, at the equator, and where the vertical rotation gradient vanishes (32.°3) for longitude wavenumbers m from 1 to >10. High latitudes are much more unstable than low latitudes, but both have e -folding times that are much shorter than a sunspot cycle. The higher the m and the steeper the decline in effective gravity, the closer the unstable mode peak to the top boundary, where the energy available to drive instability is greatest. The effect of the toroidal field is always stabilizing, shrinking the latitude ranges of instability as the toroidal field is increased. The larger the toroidal field, the smaller the longitudinal wavenumber of the most unstable disturbance. All latitudes become stable for a toroidal field exceeding about 4 kG. The results imply that baroclinic instability should occur in the tachocline at latitudes where the toroidal field is weak or is changing sign, but not where the field is strong.
Honda, M.; Satake, S.; Suzuki, Y.; Shinohara, K.; Yoshida, M.; Narita, E.; Nakata, M.; Aiba, N.; Shiraishi, J.; Hayashi, N.; Matsunaga, G.; Matsuyama, A.; Ide, S.
2017-11-01
Capabilities of the integrated framework consisting of TOPICS, OFMC, VMEC and FORTEC-3D, have been extended to calculate toroidal rotation in fully non-axisymmetric perturbed magnetic fields for demonstrating operation scenarios in actual tokamak geometry and conditions. The toroidally localized perturbed fields due to the test blanket modules and the tangential neutral beam ports in ITER augment the neoclassical toroidal viscosity (NTV) substantially, while do not significantly influence losses of beam ions and alpha particles in an ITER L-mode discharge. The NTV takes up a large portion of total torque in ITER and fairly decelerates toroidal rotation, but the change in toroidal rotation may have limited effectiveness against turbulent heat transport. The error field correction coils installed in JT-60SA can externally apply the perturbed fields, which may alter the NTV and the resultant toroidal rotation profiles. However, the non-resonant n=18 components of the magnetic fields arising from the toroidal field ripple mainly contribute to the NTV, regardless of the presence of the applied field by the coil current of 10 kA , where n is the toroidal mode number. The theoretical model of the intrinsic torque due to the fluctuation-induced residual stress is calibrated by the JT-60U data. For five JT-60U discharges, the sign of the calibration factor conformed to the gyrokinetic linear stability analysis and a range of the amplitude thereof was revealed. This semi-empirical approach opens up access to an attempt on predicting toroidal rotation in H-mode plasmas.
Influence of toroidal magnetic field in multi-accreting tori
Pugliese, D.; Montani, G.
2018-02-01
We analyzed the effects of a toroidal magnetic field in the formation of several magnetized accretion tori, dubbed as ringed accretion disks (RADs), orbiting around one central Kerr supermassive Black Hole (SMBH) in AGNs, where both corotating and counterotating disks are considered. Constraints on tori formation and emergence of RADs instabilities, accretion onto the central attractor and tori collision emergence, are investigated. The results of this analysis show that the role of the central BH spin-mass ratio, the magnetic field and the relative fluid rotation and tori rotation with respect the central BH, are crucial elements in determining the accretion tori features, providing ultimately evidence of a strict correlation between SMBH spin, fluid rotation and magnetic fields in RADs formation and evolution. More specifically we proved that magnetic field and disks rotation are in fact strongly constrained, as tori formation and evolution in RADs depend on the toroidal magnetic fields parameters. Eventually this analysis identifies specific classes of tori, for restrict ranges of magnetic field parameter, that can be observed around some specific SMBHs identified by their dimensionless spin.
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)
System design of toroidal field power supply of CDD tokamak
Energy Technology Data Exchange (ETDEWEB)
Liu, Zheng Zhi
1996-12-01
This report deals with system design of Toroidal Field Power Supply of CDD tokamak (CDD-TFPS). The general design philosophy and design variations are introduced. After the outline of CDD-TFPS, the short-circuit calculation, the evaluation of converter parameters, the compatibility of converter and line are carried out. the specifications of major components, semi-conductor devices and accessories are given. High attention is paid to protection system. The design of sub-control and grounding system are described too. Some more general material for power supply design are attached in appendices for reference. (author). 30 tabs., 21 figs.
Representation of magnetic fields with toroidal topology in terms of field-line invariants
International Nuclear Information System (INIS)
Lewis, H.R.
1990-01-01
Beginning with Boozer's representation of magnetic fields with toroidal topology [Phys. Fluids 26, 1288 (1983)], a general formalism is presented for the representation of any magnetic field with toroidal topology in terms of field-line invariants. The formalism is an application to the magnetic field case of results developed recently by Lewis et al. (submitted for publication to J. Phys. A) for arbitrary time-dependent Hamiltonian systems with one degree of freedom. Every magnetic field with toroidal topology can be associated with time-dependent Hamiltonian systems with one degree of freedom and every time-dependent Hamiltonian system with one degree of freedom can be associated with magnetic fields with toroidal topology. In the Hamiltonian context, given any particular function I(q,p,t), Lewis et al. derived those Hamiltonians for which I(q,p,t) is an invariant. In addition, for each of those Hamiltonians, they derived a function canonically conjugate to I(q,p,t) that is also an invariant. They applied this result to the case where I(q,p,t) is expressed as a function of two canonically conjugate functions. This general Hamiltonian formalism provides a basis for representing magnetic fields with toroidal topology in terms of field-line invariants. The magnetic fields usually contain plasma with flow and anisotropic pressure. A class of fields with or without rotational symmetry is identified for which there are magnetic surfaces. The formalism is developed for application to the case of vacuum magnetic fields
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
The toroidal field magnet concept of ASDEX Upgrade
International Nuclear Information System (INIS)
Jandl, O.; Kollotzek, H.; Springmann, E.; Streibl, B.
1983-01-01
ASDEX Upgrade (UG), a divertor tokamak with a minor plasma radius of a = 0.5 m and a plasma current of 1.2 to 1.5 MA, is intended to succeed ASDEX. A major target of this experiment is to investigate a reactor-compatible plasma boundary. This requires according to a toroidal field (B 0 ) at the plasma centre normalized to the aspect ratio (A) of B 0 /A approximately = 1.2. The optimum with due allowance for physical requirements and technical constraints of the complete tokamak system was obtained in this case for B 0 = 3.9 T (A = 3.25) and a plasma radius of 1.63 m. The toroidal field (TF) magnet designed to meet these requirements is presented. Aspects of its turnover structure such as force transfer, coil housing and access to the plasma vessel are described. The coil concept developed in collaboration with industry is also presented, in particular the conductor concept and the current terminals and water manifold designs. Finally, the results of the cooling and stress analysis are summarized. (author)
Physics models in the toroidal transport code PROCTR
Energy Technology Data Exchange (ETDEWEB)
Howe, H.C.
1990-08-01
The physics models that are contained in the toroidal transport code PROCTR are described in detail. Time- and space-dependent models are included for the plasma hydrogenic-ion, helium, and impurity densities, the electron and ion temperatures, the toroidal rotation velocity, and the toroidal current profile. Time- and depth-dependent models for the trapped and mobile hydrogenic particle concentrations in the wall and a time-dependent point model for the number of particles in the limiter are also included. Time-dependent models for neutral particle transport, neutral beam deposition and thermalization, fusion heating, impurity radiation, pellet injection, and the radial electric potential are included and recalculated periodically as the time-dependent models evolve. The plasma solution is obtained either in simple flux coordinates, where the radial shift of each elliptical, toroidal flux surface is included to maintain an approximate pressure equilibrium, or in general three-dimensional torsatron coordinates represented by series of helical harmonics. The detailed coupling of the plasma, scrape-off layer, limiter, and wall models through the neutral transport model makes PROCTR especially suited for modeling of recycling and particle control in toroidal plasmas. The model may also be used in a steady-state profile analysis mode for studying energy and particle balances starting with measured plasma profiles.
Photoelastic and analytical investigation of stress in toroidal magnetic field coils
International Nuclear Information System (INIS)
Pih, H.; Gray, W.H.
1975-01-01
A series of two-dimensional photoelastic stress analyses on circular and oval toroidal magnetic field coils for fusion reactors were made. The circumferential variation of the coil's magnetic force was simulated by applying different pressures to sixteen segmented regions of the inner surface of the models. Isochromatics and isoclinics were measured at selected points on the loaded model in a transmission polariscope using a microphotometer. Separate principal stresses were obtained using the combination of photoelastic information and isopachic data measured from the solution of Laplace's equation by the electrical analog method. Analysis of the same coil geometries, loadings, and boundary conditions were made using the finite element method. General agreement between theory and experiment was realized. From this investigation several variations of coil geometry and methods of support were evaluated. Based upon this experiment, suggestions for optimum structural design of toroidal field coils are presented
Mcdonough, T. R.
1974-01-01
The trapping of Titan's escaping atmosphere in the Saturnian system by a toroidal ring is discussed. The radius of the toroid is comparable to Titan's orbit, or about ten times larger than the visible rings. Theoretical atmospheric models are formulated that consider Saturn's gravitational attraction and magnetospheric properties in forming this toroid and in protecting toroid particles from direct ionization by solar wind particles.
Development and verification of printed circuit board toroidal transformer model
DEFF Research Database (Denmark)
Pejtersen, Jens; Mønster, Jakob Døllner; Knott, Arnold
2013-01-01
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......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...
Commercial tokamak reactors with resistive toroidal field magnets
International Nuclear Information System (INIS)
Bombery, L.; Cohn, D.R.; Jassby, D.L.
1984-01-01
Scaling relations and design concepts are developed for commercial tokamak reactors that use watercooled copper toroidal field (TF) magnets. Illustrative parameters are developed for reactors that are scaled up in size from LITE test reactor designs, which use quasi-continuous copper plate magnets. Acceptably low magnet power requirements may be attainable in a moderate beta (β = 0.065) commercial reactor with a major radius of 6.2 m. The shielding thickness and magnet size are substantially reduced relative to values in commercial reactors with superconducting magnets. Operation at high beta (β = 0.14) leads to a reduction in reactor size, magnet-stored energy, and recirculating power. Reactors using resistive TF magnets could provide advantages of physically smaller devices, improved maintenance features, and increased ruggedness and reliability
Fabrication of the KSTAR toroidal field coil structure
International Nuclear Information System (INIS)
Choi, C.H.; Sa, J.W.; Park, H.K.; Hong, K.H.; Shin, H.; Kim, H.T.; Bak, J.S.; Lee, G.S.; Kwak, J.H.; Moon, H.G.; Yoon, H.H.; Lee, J.W.; Lee, S.K.; Song, J.Y.; Nam, K.M.; Byun, S.E.; Kim, H.C.; Ha, E.T.; Ahn, H.J.; Kim, D.S.; Lee, J.S.; Park, K.H.; Hong, C.D.
2005-01-01
The KSTAR toroidal field (TF) coil structure is under fabrication upon completion of engineering design and prototype construction. The prototype TF coil structure has been fabricated within allowable tolerances. Encasing of the prototype TF coil (TF00) in the prototype structure has been carried out through major processes involving a coil encasing, an enclosing weld, a vacuum pressure impregnation, and an outer surface machining. During the enclosing weld of the TF00 coil structure, we have measured temperatures and stresses on the coil surface. Assembly test had been performed with the TF00 coil structure. We have chosen Type 316LN as material of the TF coil structure. We used the narrow-gap TIG welding method. Doosan Heavy Industries and Construction Company (DHI) will complete the fabrication of the TF coil structure in Feb. 2006. (author)
Manufacturing aspects of toroidal field magnets for tokamak power reactors
International Nuclear Information System (INIS)
Smith, G.E.
1977-01-01
The manufacturing aspects of two different toroidal field (TF) coils are discussed briefly. The first of these is the Tokamak Fusion Test Reactor (TFTR) TF coil, which is presently in the design phase at the Princeton Plasma Physics Laboratory. The second coil configuration reflects a reference design for a large experimental power reactor (EPR) which originated at the Oak Ridge National Laboratory. This configuration was used by the Grumman Aerospace Corporation of Bethpage, N.Y. as the basis for an investigation of the manufacturing aspects of a large superconducting TF coil, the results of which are summarized. For each of these coils, the major characteristics of the design are first briefly described and the significant manufacturing aspects are then summarized
Influence of the magnetic toroidal field on the design of magnet systems for future fusion reactors
International Nuclear Information System (INIS)
Duchateau, J.L.
2006-01-01
It is often stated that an increase of the toroidal magnetic field on the plasma axis of tokamaks could be beneficial for future fusion reactors and will help in the economic viability of this new source of energy. After the development associated with ITER magnets regarding prototype conductors, joints and model coils, it is now possible to have a realistic approach of the design of magnet systems for fusion application and in particular of the toroidal field (TF) conductor design. This approach is meaningful since the ITER size is relevant to that of future fusion reactors. A demonstration reactor, the construction of which is supposed to start in 20 years would likely not be very different of ITER as for the magnet system
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)
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
Superconducting toroidal field coil current densities for the TFCX
International Nuclear Information System (INIS)
Kalsi, S.S.; Hooper, R.J.
1985-04-01
A major goal of the Tokamak Fusion Core Experiment (TFCX) study was to minimize the size of the device and achieve lowest cost. Two key factors influencing the size of the device employing superconducting magnets are toroidal field (TF) winding current density and its nuclear heat load withstand capability. Lower winding current density requires larger radial build of the winding pack. Likewise, lower allowable nuclear heating in the winding requires larger shield thickness between the plasma and coil. In order to achieve a low-cost device, it is essential to maximize the winding's current density and nuclear heating withhstand capability. To meet the above objective, the TFCX design specification adopted as goals a nominal winding current density of 3500 A/cm 2 with 10-T peak field at the winding and peak nuclear heat load limits of 1 MW/cm 3 for the nominal design and 50 MW/cm 3 for an advanced design. This study developed justification for these current density and nuclear heat load limits
Fluid models for kinetic effects in toroidal plasmas
International Nuclear Information System (INIS)
Smolyakov, A.I.; Hirose, A.; Yagi, M.; Callen, J.D.
1995-01-01
Fluid models for toroidal plasma are considered paying particular attention to the effects of particle motion along the equilibrium magnetic field. It is shown that the basic fluid equations can be obtained either as moments of the drift-kinetic equation, or from the standard fluid equations by expanding them in 1/B small parameter. It is shown that the collisionless gyroviscosity accounts for the effects of the particle magnetic drift in the parallel component of the momentum balance equation. Simple truncated model of the plasma response for arbitrary ω D (magnetic drift frequency) and k parallel V t (parallel transit frequency) is proposed. In the absence of resonances, which can be inhibited by the particle magnetic drift, this model recovers the exact kinetic results with satisfactory accuracy. In general case, the kinetic closure for the effects of the particle motion along the magnetic field is suggested in terms of the parallel viscosity and the heat flux. They are directly calculated from the linear drift-kinetic equation. Simplified expressions in the different asymptotic limits are derived
Validation of Helium Inlet Design for ITER Toroidal Field Coil
Boyer, C; Hamada, K; Foussat, A; Le Rest, M; Mitchell, N; Decool, P; Savary, F; Sgobba, S; Weiss, K-P
2014-01-01
The ITER organization has performed design and its validation tests on a helium inlet structure for the ITER Toroidal Field (TF) coil under collaboration with CERN, KIT, and CEA-Cadarache. Detailed structural analysis was performed in order to optimize the weld shape. A fatigue resistant design on the fillet weld between the shell covers and the jacket is an important point on the helium inlet structure. A weld filler material was selected based on tensile test at liquid helium temperature after Nb3Sn reaction heat treatment. To validate the design of the weld joint, fatigue tests at 7 K were performed using heat-treated butt weld samples. A pressure drop measurement of a helium inlet mock-up was performed by using nitrogen gas at room temperature in order to confirm uniform flow distribution and pressure drop characteristic. These tests have validated the helium inlet design. Based on the validation, Japanese and European Union domestic agencies, which have responsibilities of the TF coil procurement, are pr...
International Nuclear Information System (INIS)
Tang, X. Z.
2000-01-01
Subtleties of implementing the standard perfectly conducting wall boundary condition in a general toroidal geometry are clarified for a mixed scalar magnetic field representation. An iterative scheme based on Ohm's law is given
Calculation of modification to the toroidal magnetic field of the Tokamak Novillo. Part II
International Nuclear Information System (INIS)
Melendez L, L.; Chavez A, E.; Colunga S, S.; Valencia A, R.; Lopez C, R.; Gaytan G, E.
1992-03-01
In a cylindrical magnetic topology. the confined plasma experiences 'classic' collisional transport phenomena. When bending the cylinder with the purpose of forming a toro, the magnetic field that before was uniform now it has a radial gradient which produces an unbalance in the magnetic pressure that is exercised on the plasma in the transverse section of the toro. This gives place to transport phenomena call 'neo-classicist'. In this work the structure of the toroidal magnetic field produced by toroidal coils of triangular form, to which are added even of coils of compensation with form of half moon is analyzed. With this type of coils it is looked for to minimize the radial gradient of the toroidal magnetic field. The values and characteristics of B (magnetic field) in perpendicular planes to the toro in different angular positions in the toroidal direction, looking for to cover all the cases of importance are exhibited. (Author)
Safety analysis of superconducting toroidal field magnet for tokamak experimental fusion reactor
International Nuclear Information System (INIS)
1979-02-01
Safety analysis of the superconducting toroidal field magnet for a Tokamak experimental fusion reactor has been carried out. Works were accident classification, FMEA and FTA analyses, coil stability and quench behavior calculations, failure detection and coil protection system designs, structure analysis, fracture and fatigue studies, and earthquake response analysis. Accident analysis of cryostat and refrigeration system was also performed. The objective of this work is to reveal technological problems of the toroidal field magnet by safety analysis. (author)
JT-60SA Toroidal Field Coils test cryostat development
Energy Technology Data Exchange (ETDEWEB)
Jamotton, Pierre, E-mail: pjamotton@ulg.ac.be [Centre Spatial de Liège (CSL), Université de Liège Avenue du Pré-Aily, B-4031 Angleur (Belgium); Wanner, Manfred [F4E Broader Fusion Development Dept., Boltzmannstr. 2, D-85748 Garching (Germany); Massaut, Vincent [SCK/CEN, Boeretang 200 2400 Mol (Belgium); Génini, Laurent; Maksoud, Walid Abdel [CEA/DSM/IRFU CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France); Collin, Bill; Delrez, Christophe [Ateliers de la Meuse (ALM), Rue Ernest Solvay, 107, B-4000 Sclessin (Belgium)
2013-10-15
Highlights: ► Large vacuum vessels. ► FEM mechanical design. ► Cryogenic thermal design. ► Full development process: design, manufacturing, assembly, test. -- Abstract: Within the Broader Approach Agreement, Fusion for Energy will deliver to the Japanese Atomic Energy Association, amongst other components, the 18 Toroidal Field Coils (TFCs) for the superconducting Tokamak JT-60SA [1]. These coils will be individually tested at cryogenic temperatures and at the nominal current in a test cryostat. This cryostat is provided as an in-kind contribution by Belgium and is being developed jointly with CEA-Saclay/France. The vessel is large, oval shaped with an overall length of 11 m, a width of 7.2 m and a height of 6.5 m. To reduce the heat load to the coils the cryostat is covered by LN{sub 2} cooled thermal shields. In addition to the cryostat, three test frames for the coils, the valve box vessel and the insulation vacuum system are also provided by Belgium. The Belgian contribution is design, manufacturing, assembly and test of the vacuum chamber, thermal shield and test frames by the Belgian company Ateliers de la Meuse (ALM), with the support of Centre Spatial de Liège (CSL). The TF coil test facility is assembled and the coil tests are performed by CEA/Saclay. The Belgian contribution, namely the design, manufacturing, assembly and test of the vacuum vessel, the thermal shields, and the test frames as well as of the vacuum pumping system are described in the presentation.
Flow balancing orifice for ITER toroidal field coil
Litvinovich, A. V.; Y Rodin, I.; Kovalchuk, O. A.; Safonov, A. V.; Stepanov, D. B.; Guryeva, T. M.
2017-12-01
Flow balancing orifices (FBOs) are used in in International thermonuclear experimental reactor (ITER) Toroidal Field coil to uniform flow rate of cooling gas in the side double pancakes which have a different conductor length: 99 m and 305 m, respectively. FBOs consist of straight parts, elbows produced from a 316L stainless steel tube 21.34 x 2.11 mm and orifices made from a 316L stainless steel rod. Each of right and left FBOs contains 6 orifices, straight FBOs contain 4 and 6 orifices. Before manufacturing of qualification samples D.V. Efremov Institute of Electrophysical Apparatus (JSC NIIEFA) proposed to ITER a new approach to provide the seamless connection between a tube and a plate therefore the most critical weld between the orifice with 1 mm thickness and the tube removed from the FBOs final design. The proposed orifice diameter is three times less than the minimum requirement of the ISO 5167, therefore it was tasked to define accuracy of calculation flow characteristics at room temperature and compare with the experimental data. In 2015 the qualification samples of flow balancing orifices were produced and tested. The results of experimental data showed that the deviation of calculated data is less than 7%. Based on this result and other tests ITER approved the design of FBOs, which made it possible to start the serial production. In 2016 JSC NIIEFA delivered 50 FBOs to ITER, i.e. 24 left side, 24 right side and 2 straight FBOs. In order to define the quality of FBOs the test facility in JSC NIIEFA was prepared. The helium tightness test at 10-9 m3·Pa/s the pressure up to 3 MPa, flow rate measuring at the various pressure drops, the non-destructive tests of orifices and weld seams (ISO 5817, class B) were conducted. Other tests such as check dimensions and thermo cycling 300 - 80 - 300 K also were carried out for each FBO.
Toroidal fusion reactor design based on the reversed-field pinch
International Nuclear Information System (INIS)
Hagenson, R.L.
1978-07-01
The toroidal reversed-field pinch (RFP) achieves gross equilibrium and stability with a combination of high shear and wall stabilization, rather than the imposition of tokamak-like q-constraints. Consequently, confinement is provided primarily by poloidal magnetic fields, poloidal betas as large as approximately 0.58 are obtainable, the high ohmic-heating (toroidal) current densities promise a sole means of heating a D-T plasma to ignition, and the plasma aspect ratio is not limited by stability/equilibrium constraints. A reactor-like plasma model has been developed in order to quantify and to assess the general features of a power system based upon RFP confinement. An ''operating point'' has been generated on the basis of this plasma model and a relatively detailed engineering energy balance. These results are used to generate a conceptual engineering model of the reversed-field pinch reactor (RFPR) which includes a general description of a 750 MWe power plant and the preliminary consideration of vacuum/fueling, first wall, blanket, magnet coils, iron core, and the energy storage/transfer system
Toroidal electric field in front of the lower hybrid grill of the castor tokamak
International Nuclear Information System (INIS)
Zacek, F.; Petrzilka, V.; Devynck, P.; Goniche, M.
2003-01-01
A small tokamak Castor (R/a = 0.4/0.85 m) with low plasma energy density and short pulses (20 ms) offers a unique possibility to carry out probe measurements in front of the grill antenna and as a consequence to provide direct information about the local electric fields in this region. For measurements of the toroidal electrical field, a small double probe with 2 tips separated by 3.5 mm in the toroidal direction has been used. The tips are oriented in the radial direction. The probe is radially movable in front of the central grill waveguide. Cross-correlations and FFT (fast Fourier transform) analysis of the measured V fl signals are given together with an attempt to investigate characteristics of toroidal electric field E tor (up to 500 kHz), derived from V fl measured by 2 toroidally separated tips
Barrel Toroid fully charged to nominal field, and it works!
Herman ten Kate
After a few weeks of testing up to intermediate currents, finally, on Thursday evening November 9, the current in the Barrel Toroid was pushed up to its nominal value of 20500 A and even 500 A beyond this value to prove that we have some margin. It went surprisingly well. Of course, the 8 coils forming the toroid were already tested individually at the surface but still, some surprise may have come from those parts added to the toroid in the cavern for the first time like the 8 cryoring sections linking the coils as well as the valve box at the bottom in sector 13 regulating the helium flow or the current lead cryostat on the top in sector 5. No training quenches, nothing to worry about, and the test was concluded with a fast dump triggered at 00:40 in the very early morning of November 10. (left) The toroid current during the evening and night of November 9. (right) The test crew oscillated between fear and hope while looking at the control panels as the current approached 21kA. Big relief was in the...
Fluid Motion and the Toroidal Magnetic Field Near the Top of Earth's Liquid Outer Core.
Celaya, Michael Augustine
This work considers two unresolved problems central to the study of Earth's deep interior: (1) What is the surface flow of the complete three dimensional motion sustaining the geomagnetic field in the fluid outer core? (2) How strong is the toroidal component of that field just beneath the mantle inside the core?. A solution of these problems is necessary to achieve even a basic understanding of magnetic field generation, and core-mantle interactions. Progress in solving (1) is made by extending previous attempts to resolve the core surface flow, and identifying obstacles which lead to distorted solutions. The extension relaxes the steady motions constraint. This permits more realistic solutions which should resemble more closely the real Earth flow. A difficulty with the assumption of steady flow is that if the real motion is unsteady, as it is likely to be, then steady models will suffer from aliasing. Aliased solutions can be highly corrupted. The effects of aliasing incurred through model underparametrization are explored. It is found that flow spectral energy must fall rapidly with increasing degree to escape aliasing's distortion. Damping does not appear to remedy the problem, but in fact obscures it by forcing the solution to converge upon a single, but possibly still aliased estimate. Inversions of a magnetic field model for unsteady motions, indicate steady flows are indeed aliased in time. By comparison, unsteady flows appear free of aliasing and show significant temporal variation, changing by about 30% of their magnitude over 20 years. However, it appears that noise in the high degree secular variation (SV) data used to determine the flow acts as a further impediment to solving (1). Damping is shown to be effective in removing noise, but only once aliasing is no longer a factor and noise is restricted to that part of the SV which makes only a small contribution to the solution. To solve (2) the radial component of Ohm's law is inverted for the toroidal
Experimental simulation of pulsed field losses in tokamak toroidal field coils
International Nuclear Information System (INIS)
Miller, J.R.; Shen, S.S.
1976-01-01
Experiments have been carried out to measure loss in a twisted multifilamentary composite superconductor when exposed to a transient longitudinal field. We investigate the variation of losses both as a function of transverse applied field and of sample transport current. Losses are probed mainly by measurement of the dynamic resistivity of the sample during the longitudinal pulse. Experimental results are compared with theories for the zero transport current case. The extension of theory to include transport current is also discussed, and the impact on tokamak toroidal field coil design is considered
Force-free field inside a toroidal magnetic cloud
Czech Academy of Sciences Publication Activity Database
Romashets, E. P.; Vandas, Marek
2003-01-01
Roč. 30, č. 20 (2003), s. 2065, /SSC 8-1 - SSC 8-4/ ISSN 0094-8276 R&D Projects: GA AV ČR IBS1003006; GA ČR GA205/03/0953 Institutional research plan: CEZ:AV0Z1003909 Keywords : magnetic clouds * toroid al flux rope * analytical solution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.422, year: 2003
Air core poloidal magnetic field system for a toroidal plasma producing device
International Nuclear Information System (INIS)
Marcus, F.B.
1978-01-01
A poloidal magnetics system for a plasma producing device of toroidal configuration is provided that reduces both the total volt-seconds requirement and the magnitude of the field change at the toroidal field coils. The system utilizes an air core transformer wound between the toroidal field (TF) coils and the major axis outside the TF coils. Electric current in the primary windings of this transformer is distributed and the magnetic flux returned by air core windings wrapped outside the toroidal field coils. A shield winding that is closely coupled to the plasma carries a current equal and opposite to the plasma current. This winding provides the shielding function and in addition serves in a fashion similar to a driven conducting shell to provide the equilibrium vertical field for the plasma. The shield winding is in series with a power supply and a decoupling coil located outside the TF coil at the primary winding locations. The present invention requires much less energy than the usual air core transformer and is capable of substantially shielding the toroidal field coils from poloidal field flux
Rotation and toroidal magnetic field effects on the stability of two-component jets
Millas, Dimitrios; Keppens, Rony; Meliani, Zakaria
2017-09-01
Several observations of astrophysical jets show evidence of a structure in the direction perpendicular to the jet axis, leading to the development of 'spine and sheath' models of jets. Most studies focus on a two-component jet consisting of a highly relativistic inner jet and a slower - but still relativistic - outer jet surrounded by an unmagnetized environment. These jets are believed to be susceptible to a relativistic Rayleigh-Taylor-type instability, depending on the effective inertia ratio of the two components. We extend previous studies by taking into account the presence of a non-zero toroidal magnetic field. Different values of magnetization are examined to detect possible differences in the evolution and stability of the jet. We find that the toroidal field, above a certain level of magnetization σ, roughly equal to 0.01, can stabilize the jet against the previously mentioned instabilities and that there is a clear trend in the behaviour of the average Lorentz factor and the effective radius of the jet when we continuously increase the magnetization. The simulations are performed using the relativistic MHD module from the open source, parallel, grid adaptive, mpi-amrvac code.
INSTABILITY OF NON-UNIFORM TOROIDAL MAGNETIC FIELDS IN ACCRETION DISKS
Energy Technology Data Exchange (ETDEWEB)
Hirabayashi, Kota; Hoshino, Masahiro, E-mail: hirabayashi-k@eps.s.u-tokyo.ac.jp [Department of Earth and Planetary Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2016-05-10
We present a new type of instability that is expected to drive magnetohydrodynamic (MHD) turbulence from a purely toroidal magnetic field in an accretion disk. It is already known that in a differentially rotating system, the uniform toroidal magnetic field is unstable due to magnetorotational instability (MRI) under a non-axisymmetric and vertical perturbation, while it is stable under a purely vertical perturbation. Contrary to the previous study, this paper proposes an unstable mode completely confined to the equatorial plane, driven by the expansive nature of the magnetic pressure gradient force under a non-uniform toroidal field. The basic nature of this growing eigenmode, which we name “magneto-gradient driven instability,” is studied using linear analysis, and the corresponding nonlinear evolution is then investigated using two-dimensional ideal MHD simulations. Although a single localized magnetic field channel alone cannot provide sufficient Maxwell stress to contribute significantly to the angular momentum transport, we find that the mode coupling between neighboring toroidal fields under multiple localized magnetic field channels drastically generates a highly turbulent state and leads to the enhanced transport of angular momentum, which is comparable to the efficiency seen in previous studies on MRIs. This horizontally confined mode may play an important role in the saturation of an MRI through complementray growth with the toroidal MRIs and coupling with magnetic reconnection.
The vacuum-arc plasma motion in a toroidal magnetic field
International Nuclear Information System (INIS)
Timoshenko, A.I.; Gnybida, M.V.; Taran, V.S.; Tereshin, V.I.; Chechelnitskij, O.G.
2005-01-01
The separation of the vacuum-arc plasma from macro-particles in the curvilinear plasma filters allows obtaining coatings with especially high characteristics. However, inside such filters the significant plasma losses also have been occurred. At the same time, increasing in the filter's efficiency is a difficult task without an effective mathematical model that really would describe the vacuum-arc plasma motion in a toroidal magnetic field. The description based on the flax-tube model was in fact only the first approximation in the decision of this problem. According to detailed flax-tube analysis of ions passage through the quarter torus plasma guide, the efficiency of the filter should grow up to 85% as the positive potential U, applied to the body of the plasma guide, is on the increase. However, the experiment showed that maximum of transparency reach up to ∼ 12%, at potential about of +18 Volts, and comes down under the further increase in potential. Such big digression from experiment does not justify the use of flux-tube model for designing of curvilinear plasma filters. We offer the new approach to the description of the vacuum-arc plasma motion in a toroidal magnetic field based on the solutions of steady-state (∂/∂t=0) Vlasov-Maxwell equations for the long plasma column aligned parallel to a constant axial magnetic field. The relations for the self-consistent electric polarization fields, which appear due to displacement of the electron component from ionic one on the curvilinear part of motion, were derived within a framework of the drift approximation. The dynamics of the central part of the plasma flow in the electric polarization fields was considered in detail. The displacement of the plasma flow at the output of the plasma guide was calculated for the carbon and titanium plasmas. The good agreement with the experimental data was obtained. (author)
Passing particle toroidal precession induced by electric field in a tokamak
International Nuclear Information System (INIS)
Andreev, V. V.; Ilgisonis, V. I.; Sorokina, E. A.
2013-01-01
Characteristics of a rotation of passing particles in a tokamak with radial electric field are calculated. The expression for time-averaged toroidal velocity of the passing particle induced by the electric field is derived. The electric-field-induced additive to the toroidal velocity of the passing particle appears to be much smaller than the velocity of the electric drift calculated for the poloidal magnetic field typical for the trapped particle. This quantity can even have the different sign depending on the azimuthal position of the particle starting point. The unified approach for the calculation of the bounce period and of the time-averaged toroidal velocity of both trapped and passing particles in the whole volume of plasma column is presented. The results are obtained analytically and are confirmed by 3D numerical calculations of the trajectories of charged particles
Toroidal magnetic field system for 2-MA reversed-field pinch experiment
Melton, J. G.; Linton, T. W.
The engineering design of the toroidal magnetic field (TF) system for a 2-MA Reversed Field Pinch experiment (ZT-H) is described. ZT-H is designed with major radius 2.15 meters, minor radius 0.40 meters, and a peak toroidal magnetic field of 0.85 Tesla. The requirement for highly uniform fields, with spatial ripple 0.2% leads to a design with 72 equally spaced circular TF coils, located at minor radius 0.6 meters, carrying a maximum current of 9.0 MA. The coils are driven by a 12-MJ capacitor bank which is allowed to ring in order to aid the reversal of magnetic field. A stress analysis is presented, based upon calculated loop tension, centering force, and overturning moment, treating these as a combination of static loads and considering that the periodic nature of the loading causes little amplification. The load transfer of forces and moments is considered as a stress distribution resisted by the coils, support structures, wedges, and the structural shell.
Energy Technology Data Exchange (ETDEWEB)
Chavez A, E.; Melendez L, L.; Colunga S, S.; Valencia A, R.; Lopez C, R.; Gaytan G, E
1991-07-15
The charged particles that constitute the plasma in the tokamaks are located in magnetic fields that determine its behavior. The poloidal magnetic field of the plasma current and the toroidal magnetic field of the tokamak possess relatively big gradients, which produce drifts on these particles. These drifts are largely the cause of the continuous lost of particles and of energy of the confinement region. In this work the results of numerical calculations of a modification to the 'traditional' toroidal magnetic field that one waits it diminishes the drifts by gradient and improve the confinement properties of the tokamaks. (Author)
Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks
Energy Technology Data Exchange (ETDEWEB)
Hong, Qin; Guan, Xiaoyin; Fisch, Nathaniel J.
2011-07-19
In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ({var_epsilon}{sup -1}) larger than the E x B velocity, where {var_epsilon} is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.
Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks
International Nuclear Information System (INIS)
Qin, Hong; Guan, Xiaoyin; Fisch, Nathaniel J.
2011-01-01
In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ((var e psilon) -1 ) larger than the E x B velocity, where (var e psilon) is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.
Toroidal rotation braking with n = 1 magnetic perturbation field on JET
DEFF Research Database (Denmark)
Sun, Y; Liang, Y; Koslowski, H R
2010-01-01
A strong toroidal rotation braking has been observed in plasmas with application of an n = 1 magnetic perturbation field on the JET tokamak. Calculation results from the momentum transport analysis show that the torque induced by the n = 1 perturbation field has a global profile. The maximal value...
Performance assessment and optimization of the ITER toroidal field coil joints
Rolando, G.; Foussat, A.; Knaster, J.; Ilyin, Y.; Nijhuis, Arend
2013-01-01
The ITER toroidal field (TF) system features eighteen coils that will provide the magnetic field necessary to confine the plasma. Each winding pack is composed of seven double pancakes (DP) connected through praying hands joints. Shaking hands joints are used to interface the terminals of the
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.
Computer simulation of containment of electron clouds in a toroidal magnetic field
International Nuclear Information System (INIS)
Abe, H.
1977-01-01
The quiescent confinement of non-neutral electron clouds in a toroidal magnetic field is confirmed by a computer simulation using a finite-sized particle model. For a uniform density, we obtain 0.08 as the maximum of the ratio q(ω 2 sub(p)/ω 2 sub(c)). This value is larger by a factor of 4 than that achieved in experiments and reasonable from the theoretical and empirical evidence. The stable l =1 dioctron modes, the amplitudes of which can be controlled by the initial conditions, are observed to spoil the confinement time. Various physical quantities such as electrostatic potentials, decay times, and kinetic temperatures are measured and compared with the equilibrium theory. (author)
International Nuclear Information System (INIS)
Chatthong, B.; Picha, R.; Poolyarat, N.; Onjun, T.
2014-01-01
This work aims to study effects of toroidal flow on the L-H transition phenomenon in tokamak plasmas using bifurcation concept. Two-field (thermal and particle) transport equations with both neoclassical and turbulent effects included are solved simultaneously. The transport suppression mechanism used in this work is flow shear, which is assumed to affect only the turbulent transport. The flow shear can be calculated from the force balance equation with toroidal flow as a main contributor. The toroidal velocity profile is calculated using three different models. The first model is an empirical model in which the velocity is dependent on local ion temperature. The second model is based on neoclassical toroidal viscosity theory in which the velocity is driven by ion temperature gradient. In the third model, the velocity is dependent on current density flow in plasma. The two transport equations are solved both analytically and numerically using MATLAB to study the criteria for H-mode formation, pedestal width and its dynamics. The results from three toroidal velocity models are compared and analyzed with respect to bifurcation behavior and plasma performance.
Internal Field of Homogeneously Magnetized Toroid Sensor for Proton Free Precession Magnetometer
DEFF Research Database (Denmark)
Primdahl, Fritz; Merayo, José M.G.; Brauer, Peter
2005-01-01
The shift of the NMR spectral line frequency in a proton free precession absolute scalar magnetometer using the omni-directional toroid container for a proton-rich liquid depends on the magnetic susceptibility of the liquid and on the direction of the external field relative to the axis of the to......The shift of the NMR spectral line frequency in a proton free precession absolute scalar magnetometer using the omni-directional toroid container for a proton-rich liquid depends on the magnetic susceptibility of the liquid and on the direction of the external field relative to the axis...... of the toroid. The theoretical shift is estimated for water by computing the additional magnetic field from the magnetization of the liquid and comparing it to the theoretical field in a spherical container. Along the axis the estimated average shift is -0.08 nT and perpendicular to the axis the shift is +0.......08 nT relative to that of a spherical sensor. The field inhomogeneity introduced by the toroid shape amounts to 0.32 nT over the volume of the sensor and is not expected to significantly affect the signal decay time, when considering the typical water line width of about 2.5 InT....
Stability properties of a toroidal z-pinch in an external magnetic multipole field
International Nuclear Information System (INIS)
Eriksson, H.G.
1987-01-01
MHD stability of m=1, axisymmetric, external modes of a toroidal z-pinch immersed in an external multipole field (Extrap configuration) is studied. The description includes the effects of a weak toroidicity, a non-circular plasma cross-section and the influence of induced currents in the external conductors. It is found that the non-circularity of the plasma cross-section always has a destabilizing effect but that the m=1 mode can be stabilized by the external feedback if the non-circularity is small. (author)
Excitation adjustable system of toroidal field waveform for tokamak HL-1
International Nuclear Information System (INIS)
Ren Juqian; Yu Xianrong; Xie Yongzhong
1989-11-01
The closed-loop adjusting system of the toroidal field waveform is described. Technical measures have been taken to improve the stability of the system and the repetitiveness of wave adjustment. Meanwhile the wiring and technical characteristics of the system are discussed and the level of the system attained is compared with that of the original system
Momentum transport studies in JET H-mode discharges with an enhanced toroidal field ripple
de Vries, P. C.; Versloot, T. W.; Salmi, A.; Hua, M. D.; Howell, D. H.; Giroud, C.; Parail, V.; Saibene, G.; Tala, T.
2010-01-01
In this study, enhancement of the toroidal field (TF) ripple has been used as a tool in order to reveal the impact of the momentum pinch on the rotation profiles in H-mode JET discharges. The analysis showed that flatter rotation profiles were obtained in discharges with a high TF ripple, attributed
Effects of Toroidal Magnetic Fields on the Thermal Instability of Thin ...
Indian Academy of Sciences (India)
Effects of Toroidal Magnetic Fields on the Thermal Instability of Thin Accretion Disks. Sheng-Ming Zheng1, Feng Yuan2, Wei-Min Gu1,∗. & Ju-Fu Lu1. 1Department of Physics and Institute of Theoretical Physics and Astrophysics,. Xiamen University, Xiamen, Fujian 361005, China. 2Key Laboratory for Research in Galaxies ...
International Nuclear Information System (INIS)
Macdonald, D.; Watkin, D.C.; Hollis, M.J.; DePew, R.E.; Kuban, D.P.
1990-01-01
The use of deuterium-tritium fuel in the Compact Ignition Tokamak will require applying remote handling technology for ex-vessel maintenance and replacement of machine components. Highly activated and contaminated components of the fusion devices auxiliary systems, such as diagnostics and RF heating, must be replaced using remotely operated maintenance equipment in the test cell. In-vessel remote maintenance included replacement of divertor and first wall hardware, faraday shields, and for an in-vessel inspection system. Provision for remote replacement of a vacuum vessel sector, toroidal field coil or poloidal field ring coil was not included in the project baseline. As a result of recent coil failures experienced at a number of facilities, the CIT project decided to reconsider the question of remote recovery from a coil failure and, in January of 1990, initiated a coil replacement study. This study focused on the technical requirements and impact on fusion machine design associated with remote recovery from any coil failure
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
International Nuclear Information System (INIS)
Ida, Katsumi; Miura, Yukitoshi; Itoh, Sanae
1994-10-01
Radial structures of plasma rotation and radial electric field are experimentally studied in tokamak, heliotron/torsatron and stellarator devices. The perpendicular and parallel viscosities are measured. The parallel viscosity, which is dominant in determining the toroidal velocity in heliotron/torsatron and stellarator devices, is found to be neoclassical. On the other hand, the perpendicular viscosity, which is dominant in dictating the toroidal rotation in tokamaks, is anomalous. Even without external momentum input, both a plasma rotation and a radial electric field exist in tokamaks and heliotrons/torsatrons. The observed profiles of the radial electric field do not agree with the theoretical prediction based on neoclassical transport. This is mainly due to the existence of anomalous perpendicular viscosity. The shear of the radial electric field improves particle and heat transport both in bulk and edge plasma regimes of tokamaks. (author) 95 refs
Mordik, S N
2002-01-01
The third-order transfer matrices are calculated for an electrostatic toroidal sector condenser using a rigorously conserved matrix method that implies the conservation of the beam phase volume at each step in the calculations. The transfer matrices (matrizants) obtained, include the fringing-field effect due to the stray fields. In the case of a rectangular distribution of the field components along the optical axis, the analytical expressions for all aberration coefficients, including the dispersion ones, are derived accurate to the third-order terms. In simulations of real fields with the stray field width other than zero, a smooth distribution of the field components is used for which similar aberration coefficients were calculated by means of the conserved numerical method . It has been found that for a smooth model, as the stray field width tends to zero, the aberration coefficients approach the corresponding aberration values in the rectangular model.
International Nuclear Information System (INIS)
Vaulina, I.G.; Gusev, S.V.; Sivkova, G.N.
1987-01-01
Results of calculational and experimental atudy of stress-deformed state of superconducting coils of the T-15 tokamak toroidal field are presented. The calculations are made using the method of finite elements and refined theory of cores. Experimental studies were carried out using elastic tensometric model of polymer materials. Test results are compared with the calculational results. Divergence between calculational and experimental values of displacement of characteristic points in the unit does not exceed 20 %. Results of model studies confirm the expediency of the calculational model used for designing SOTP unit for the T-15 tokamak
Taylor-Couette flow stability with toroidal magnetic field
International Nuclear Information System (INIS)
Shalybkov, D
2005-01-01
The linear stability of the dissipative Taylor-Couette flow with imposed azimuthal magnetic field is considered. Unlike to ideal flow, the magnetic field is fixed function of radius with two parameters only: a ratio of inner to outer cylinder radii and a ratio of the magnetic field values on outer and inner cylinders. The magnetic field with boundary values ratio greater than zero and smaller than inverse radii ratio always stabilizes the flow and called stable magnetic field below. The current free magnetic field is the stable magnetic field. The unstable magnetic field destabilizes every flow if the magnetic field (or Hartmann number) exceeds some critical value. This instability survives even without rotation (for zero Reynolds number). For the stable without the magnetic field flow, the unstable modes are located into some interval of the vertical wave numbers. The interval length is zero for critical Hartmann number and increases with increasing Hartmann number. The critical Hartmann numbers and the length of the unstable vertical wave numbers interval is the same for every rotation law. There are the critical Hartmann numbers for m = 0 sausage and m = 1 kink modes only. The critical Hartmann numbers are smaller for kink mode and this mode is the most unstable mode like to the pinch instability case. The flow stability do not depend on the magnetic Prandtl number for m = 0 mode. The same is true for critical Hartmann numbers for m = 0 and m = 1 modes. The typical value of the magnetic field destabilizing the liquid metal Taylor-Couette flow is order of 100 Gauss
On the choice of toroidal magnetic field for thermonuclear tokamaks
International Nuclear Information System (INIS)
Segre, S.E.
1981-01-01
The value of the magnetic field chosen for tokamak experiments is the result of a compromise between physics requirements, technological limits and financial constraints. The consequences of some physics requirements and limitations, in the light of recent results on the scaling of energy confinement and on limits of density are examined. (author)
A novel superconducting toroidal field magnetic concept using advanced materials
International Nuclear Information System (INIS)
Schwartz, J.
1991-01-01
The plasma physics database indicates that two distinct approaches to tokamak design may lead to commercial fusion reactors: Low Aspect ratio, high plasma current, relatively low magnetic field devices, and high Aspect ratio, high field devices. The former requires significant enhancements in plasma performance, while the latter depends primarily upon technology development. The key technology for the commercialization of the high-field approach is large, high magnetic field superconducting magnets. In this paper, the physics motivation for the high field approach and key superconducting magnet (SCM) development issues are reviewed. Improved SCM performance may be obtained from improved materials and/or improved engineering. Superconducting materials ranging from NbTi to high-T c oxides are reviewed, demonstrating the broad range of potential superconducting materials. Structural material options are discussed, including cryogenic steel alloys and fiber-reinforced composite materials. The potential for improved magnet engineering is quantified in terms of the Virial Theorem Limit, and two examples of approaches to highly optimized magnet configurations are discussed. The force-reduced concept, which is a finite application of the force-free solutions to Ampere's Law, appear promising for large SCMs but may be limited by the electromagnetics of a fusion plasma. The Solid Superconducting Cylinder (SSC) concept is proposed. This concept combines the unique properties of high-T c superconductors within a low-T c SCM to obtain (1) significant reductions in the structural material volume, (2) a decoupling of the tri-axial (compressive and tensile) stress rate, and (3) a demountable TF magnet system. The advantages of this approach are quantified in terms of a 24 T commercial reactor TF magnet system. Significant reductions in the mechanical stress and the TF radial build are demonstrated. 54 refs., 14 figs., 5 tabs
Ideal toroidal stability β limits and shaping effects for reversed field pinch configurations
International Nuclear Information System (INIS)
Paccagnella, R.; Bondeson, A.; Luetjens, H.
1991-05-01
The influence of shaping and toroidicity on the ideal MHD stability of the Reversed Field Pinch (RFP) is investigated both with respect to current and pressure driven modes. It is found that triangularity and x-point shaping does not significantly modify the operational limits of RFP, while ellipticity and D-shaping is destabilizing. A simple relation for the stability of current driven modes is also given. (author) 12 figs., 17 refs
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)
Mazzucato, E.
2000-01-01
The next step in the demonstration of the scientific feasibility of a tokamak fusion reactor is a DT burning plasma experiment for the study and control of self-heated plasmas. In this paper, the authors examine the role of the toroidal magnetic field on the confinement of a tokamak plasma in the ELMy H-mode regime--the operational regime foreseen for ITER
Linear force-free field of a toroidal symmetry
Czech Academy of Sciences Publication Activity Database
Romashets, E. P.; Vandas, Marek
2009-01-01
Roč. 499, č. 1 (2009), s. 17-20 ISSN 0004-6361 R&D Projects: GA AV ČR(CZ) 1QS300120506; GA MŠk(CZ) ME09032; GA ČR GA205/09/0170 Institutional research plan: CEZ:AV0Z10030501 Keywords : magnetic fields * solar wind * magnetic clouds Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.179, year: 2009
Magnetic Axis Drift and Magnetic Spot Formation in Neutron Stars with Toroidal Fields
Gourgouliatos, Konstantinos N.; Hollerbach, Rainer
2018-01-01
We explore magnetic field configurations that lead to the formation of magnetic spots on the surface of neutron stars and the displacement of the magnetic dipole axis. We find that a toroidally dominated magnetic field is essential for the generation of a single spot with a strong magnetic field. Once a spot forms, it survives for several million years, even after the total magnetic field has decayed significantly. We find that the dipole axis is not stationary with respect to the neutron star’s surface and does not in general coincide with the location of the magnetic spot. This is due to non-axisymmetric instabilities of the toroidal field that displace the poloidal dipole axis at rates that may reach 0.°4 per century. A misaligned poloidal dipole axis with the toroidal field leads to more significant displacement of the dipole axis than the fully aligned case. Finally we discuss the evolution of neutron stars with such magnetic fields on the P{--}\\dot{P} diagram and the observational implications. We find that neutron stars spend a very short time before they cross the Death Line of the P{--}\\dot{P} diagram, compared to their characteristic ages. Moreover, the maximum intensity of their surface magnetic field is substantially higher than the dipole component of the field. We argue that SGR 0418+5729 could be an example of this type of behavior, having a weak dipole field, yet hosting a magnetic spot responsible for its magnetar behavior. The evolution on the pulse profile and braking index of the Crab pulsar, which are attributed to an increase of its obliquity, are compatible with the anticipated drift of the magnetic axis.
Resistive toroidal-field coils for tokamak reactors
International Nuclear Information System (INIS)
Kalnavarns, J.; Jassby, D.L.
1980-11-01
This paper analyzes the optimization of the geometry of resistive TF coils of rectangular bore for tokamak fusion test reactors and practical neutron generators. In examining the trade-offs between geometric parameters and magnetic field for reactors giving a specified neutron wall loading, either the resistive power loss or the lifetime coil cost can be minimized. Aspects of cooling, magnetic stress, and construction are addressed for several reference designs. Bending moment distributions in closed form have been derived for rectangular coils on the basis of the theory of rigid frames. Candidate methods of fabrication and of implementing demountable joints are summarized
The forming of a superconductor cable during the winding of a large toroidal field coil
International Nuclear Information System (INIS)
Messemer, G.; Zehlein, H.
1984-01-01
The feasible range for the tension force which acts on a superconductor cable during the winding of a large D-shaped toroidal field coil depends strongly on the mechanical properties of the cable, on the geometry of the winding pack and on the arrangement of the equipment. The upper limit is imposed by possible damage within the cable. The lower limit is set by the need to assure enough compaction and to overcome the friction forces between the layers. Within this 'corridor' optimal control of elastic prestresses is desirable: this may be chosen with regard to the residual stresses and/or the elastic springback after removal of the coil former. This paper presents a simplified elastica conductor model built by a finite chain of intervals with constant bending moment and curvature. This paper describes the discrete model as well as the iterative shooting method, which finds the equilibrium shape of the conductor. The distributions of bending moment and shear forces around the D-shaped contour, as well as along the conductor, are given. Desirable improvements are outlined. In particular, the possibility of mitigating the stress concentration effect by supporting rollers suitably placed along the 'free' conductor near the bobbin is discussed. (author)
Highlights from the assembly of the helical field coils for the Advanced Toroidal Facility
International Nuclear Information System (INIS)
Benson, R.D.
1985-01-01
The helical field (HF) coils in the Advanced Toroidal Facility (ATF) device consist of a set of 24 identical segments connected to form a continuous pair of helical coils wrapped around a toroidal vacuum vessel. Each segment weighs approximately 1364 kg (3000 lb) and is composed of 14 water-cooled copper plate conductors bolted to a cast stainless steel structural support member with a T-shape cross section (known as the structural tee). The segment components are electrically insulated with Kapton adhesive tape, G-10, Tefzel, and rubber to withstand 2.5 kV. As a final insulator and structural support, the entire segment is vacuum impregnated with epoxy. This paper offers a brief overview of the processes used to assemble the component parts into a completed segment, including identification of items that required special attention. 4 figs
Nonaxisymmetric Rossby vortex instability with toroidal magnetic fields in structured disks
Energy Technology Data Exchange (ETDEWEB)
Yu, Cong [Los Alamos National Laboratory; Li, Hui [Los Alamos National Laboratory
2009-01-01
We investigate the global nonaxisymmetric Rossby vortex instability (RVI) in a differentially rotating, compressible magnetized accretion disk with radial density structures. Equilibrium magnetic fields are assumed to have only the toroidal component. Using linear theory analysis, we show that the density structure can be unstable to nonaxisymmetric modes. We find that, for the magnetic field profiles we have studied, magnetic fields always provide a stabilizing effect to the unstable RVI modes. We discuss the physical mechanism of this stabilizing effect. The threshold and properties of the unstable modes are also discussed in detail. In addition, we present linear stability results for the global magnetorotational instability when the disk is compressible.
Study of a multi-hadron facility for 'PEP' based on toroidal field magnets
International Nuclear Information System (INIS)
Spillantini, P.
1974-01-01
A facility based on magnetic fields with toroidal structure is proposed for the study of the e + e/sup /minus// annihilation into multi-hadrons. Evaluations are carried out for a scheme with three toroidal superconducting coils (the 'central' coil and two 'small θ' coils) covering a 96%*4π solid angle. Very forward angles are kept free for the possible addition of two other toroidal coils covering down to /approximately/0.7/degree/. The choice of the geometrical dimensions of the 'central' and 'small θ' coils is discussed. The evaluations are made for two different geometries of the central coil, one 'large' and the other one 'compact'. The weight of the coils is very low (.3--1.5t) while a /approximately/2.5 Tesla maximum field can be obtained (/approximately/3.5 Tesla for the 'compact' central coil). A complete detection apparatus requires for the central coil ('large' version) about 600 drift wires, 1000 proportional wires, 150 photomultipliers, 40 TOF channels; from another proposal the cost of a 'MPWC+ lead glass TAC' γ-detection system can be scaled to $650K or $1100K, depending on the possible inclusion of a high pressure gas cerenkov in the apparatus. Each 'small θ' spectrometer requires /approximately/1/4 of all this. The 'compact' coil reduces the cost for the central spectrometer by a factor of 1.5--2
Evidence for Toroidal B-Field Components in AGN Jets on Kiloparsec Scales
Directory of Open Access Journals (Sweden)
Sebastian Knuettel
2017-10-01
Full Text Available Though helical magnetic fields are generally believed to arise when the jets of Active Galactic Nuclei (AGN are launched, it is still unclear what role they play (and if they survive to the largest jet scales. A helical or toroidal B-field may contribute substantially to the collimation of the jet. This B-field structure can be detected in images of the Faraday rotation measure (RM—a measure of the change in polarisation angle of an electromagnetic wave as it passes through a magneto-ionic medium. The Faraday rotation measure is directly proportional to the line-of-sight magnetic field; therefore a monotonic gradient in the RM transverse to the jet indicates similar behaviour of the line-of-sight B-field component. This type of analysis has mostly been done on parsec scales using VLBI observations at centimetre wavelengths, while relatively few studies have probed decaparsec to kiloparsec scales. The detection of RM gradients with significances of 3 σ or more on such large scales can demonstrate the presence of a toroidal field component, which may be associated with a helical field that has persisted to these distances from the centre of the AGN. We present the results of new Faraday rotation analyses for 2 AGN on kiloparsec scales based on multiwavelength VLA observations, with robust transverse RM gradients detected in both. Furthermore, the direction of the inferred toroidal B-fields on the sky supports previous results indicating a predominance of outward currents in the jets on kiloparsec scales.
Analytical modelling of resistive wall mode stabilization by rotation in toroidal tokamak plasmas
International Nuclear Information System (INIS)
Ham, C J; Gimblett, C G; Hastie, R J
2011-01-01
Stabilization of the resitive wall mode (RWM) may allow fusion power to be doubled for a given magnetic field in advanced tokamak operation. Experimental evidence from DIII-D and other machines suggests that plasma rotation can stabilize the RWM. Several authors (Finn 1995 Phys. Plasmas 2 3782, Bondeson and Xie 1997 Phys. Plasmas 4 2081) have constructed analytical cylindrical models for the RWM, but these do not deal with toroidal effects. The framework of Connor et al (1988 Phys. Fluids 31 577) is used to develop ideal plasma analytic models with toroidicity included. Stepped pressure profiles and careful ordering of terms are used to simplify the analysis. First, a current driven kink mode model is developed and a dispersion relation for arbitrary current profile is calculated. Second, the external pressure driven kink mode is similarly investigated as the most important RWM arises from this mode. Using this latter model it is found that the RWM is stabilized by Alfven continuum damping with rotation levels similar to those seen in experiments. An expression for the stability of the external kink mode for more general current profiles and a resistive wall is derived in the appendix.
STRUCTURAL RESPONSE OF THE DIII-D TOROIDAL FIELD COIL TO INCREASED LATERAL LOADS
International Nuclear Information System (INIS)
REIS, E.E; CHIN, E.
2004-03-01
OAK-B135 Recent calibration shots in which full toroidal field (TF) coil current interacted with the maximum poloidal field coils have produced increased lateral loads on the outer sections of the TF-coil. The increased lateral loads have resulted in deflections that have been sufficient to cause the TF-coil to contact adjacent equipment and produce a transient short to ground within the coil. The six outer turns of each TF-coil bundle are clamped together by insulated preloaded studs to provide increased bending stiffness. These sections of the outer bundles depend on friction to react the lateral loads as a bundle rather than six individual turns. A major concern is that the increased loads will produce slip between turns resulting in excessive lateral deflections and possible damage to the insulating sleeve on the preloaded studs. A finite element structural model of the TF-coil was developed for the calculation of deflections and the shear load distribution throughout the coil for the applied lateral loads from a full current calibration shot. The purpose of the updated structural model is to correlate the applied lateral loads to the total shear force between the unbonded sections of the outer turns. An allowable integrated lateral load applied to the outer turns is established based on the maximum shear force that can be reacted by friction. A program that calculates the magnetic fields and integrated lateral load along the outer turns can be incorporated into the plasma control system. The integrated load can then be compared to the calculated allowable value prior to execution of calibration shots. Calibration shots with a calculated total lateral load greater than the allowable value will be prevented
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.
Evaluation of inductive heating energy of ITER toroidal field conductor by calorimetry
Ozeki, H.; Suwa, T.; Saito, T.; Matsui, K.; Isono, T.; Kawano, K.; Takahashi, Y.
2017-05-01
The influence of a fast electromagnetic perturbation, such as plasma disruption, on the ITER toroidal field (TF) coil conductor was studied. When a fast magnetic field change is superimposed, the TF conductor is inductively heated by internally generated eddy currents. To measure the inductive heating (IH) energy amount by calorimetry, an IH experiment using short TF conductor samples with length of 20 cm was performed in a liquid He bath. The sample components used were a TF conductor, TF jacket and a TF conductor cable. A 60-turn, single layer solenoid coil was installed around each sample as an IH coil. Also, the Joule heat of the IH coil was solely measured to subtract its thermal contribution from the other samples. A 1 kHz sinusoidal AC current was applied to each IH coil, changing the current amplitude. The heat generated in the samples, including the IH coil, was eventually absorbed into the liquid He, and the liquid He was then vaporized. Thus, the heat amount was measured by a He level sensor inside a gas collection cylinder attached above the sample. The validity of the experimental results was confirmed by comparing them with computation results of the IH energy of the samples with a computation model. Also, the consumed energy was calculated from the measured waveforms of the applied AC voltage and current to the samples. As the result, the measured and calculated IH energy were found to be in good agreement. Finally, based on the results of the experiment, the minimum magnetic field strength, which triggers quench of the TF conductor by fast dumping like plasma disruption, was evaluated using estimated TF conductor minimum quench energy.
International Nuclear Information System (INIS)
Buncher, B.R.; Chi, J.W.H.; Fernandez, R.
1976-01-01
This report documents the principal results of a Conceptual Design Study for the Superconducting Toroidal Field System for a Tokamak Experimental Power Reactor. Two concepts are described for peak operating fields at the windings of 8 tesla, and 12 tesla, respectively. The design and manufacturing considerations are treated in sufficient detail that cost and schedule estimates could be developed. Major uncertainties in the design are identified and their potential impact discussed, along with recommendations for the necessary research and development programs to minimize these uncertainties. The minimum dimensions of a sub-size test coil for experimental qualification of the full size design are developed and a test program is recommended
Advances in the simulation of toroidal gyro Landau fluid model turbulence
International Nuclear Information System (INIS)
Waltz, R.E.; Kerbel, G.D.; Milovich, J.; Hammett, G.W.
1994-12-01
The gyro-Landau fluid (GLF) model equations for toroidal geometry have been recently applied to the study ion temperature gradient (ITG) mode turbulence using the 3D nonlinear ballooning mode representation (BMR). The present paper extends this work by treating some unresolved issues conceming ITG turbulence with adiabatic electrons. Although eddies are highly elongated in the radial direction long time radial correlation lengths are short and comparable to poloidal lengths. Although transport at vanishing shear is not particularly large, transport at reverse global shear, is significantly less. Electrostatic transport at moderate shear is not much effected by inclusion of local shear and average favorable curvature. Transport is suppressed when critical ExB rotational shear is comparable to the maximum linear growth rate with only a weak dependence on magnetic shear. Self consistent turbulent transport of toroidal momentum can result in a transport bifurcation at suffciently large r/(Rq). However the main thrust of the new formulation in the paper deals with advances in the development of finite beta GLF models with trapped electron and BMR numerical methods for treating the fast parallel field motion of the untrapped electrons
Observation of a new toroidally localized kink mode and its role in reverse-field--pinch plasmas
International Nuclear Information System (INIS)
Tamano, T.; Bard, W.D.; Chu, C.; Kondoh, Y.; La Haye, R.J.; Lee, P.S.; Saito, M.; Schaffer, M.J.; Taylor, P.L.
1987-01-01
A new type of toroidally localized kink instability, which we named the ''slinky mode,'' was observed in a reversed-field--pinch plasma in the OHTE (Ohmic heating toroidal experiment) device. It is found that the slinky mode is the result of the phase locking of several internal kink modes due to nonlinear coupling and is an effective way to approach the Taylor relaxed state
Characterization of compact-toroid injection during formation, translation, and field penetration
Energy Technology Data Exchange (ETDEWEB)
Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T. [Nihon University, Chiyoda-ku, Tokyo 101-8308 (Japan); Roche, T.; Allfrey, I.; Gota, H.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); Tajima, T. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)
2016-11-15
We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ∼1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.
Characterization of compact-toroid injection during formation, translation, and field penetration
Matsumoto, T.; Roche, T.; Allfrey, I.; Sekiguchi, J.; Asai, T.; Gota, H.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M.; Tajima, T.
2016-11-01
We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ˜1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.
Development of high-mechanical strength electrical insulations for tokamak toroidal field coils
International Nuclear Information System (INIS)
Burke, C.
1977-01-01
The electrical insulation for the TF (Toroidal Field) coils is subjected to a high interlaminar shear, tensile and compressive stresses. Two candidate epoxy/glass fiber systems using prepreg and vacuum impregnation techniques were evaluated. Specimens were prepared and processed under controlled conditions to simulate specification manufacturing procedures. The strengths of the insulation were measured in interlaminar shear, tension, compression, and combined shear and compression statically. Shear modulus determinations were also made. Various techniques of surface treatments to increase bond strengths with three resin primers were tested
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
Simulation study of toroidal phase-locking mechanism in reversed-field pinch plasma
International Nuclear Information System (INIS)
Kusano, Kanya; Tamano, Teruo; Sato, Tetsuya.
1991-02-01
The toroidal phase locking process of kink modes in the reversed-field pinch (RFP) plasma is investigated in detail by means of the magnetohydrodynamic (MHD) simulation. The physical mechanism of phase locking is clarified. The most dominant two linearly unstable kink modes rule over the evolution of other kink modes whereby phase locking takes place. It is confirmed that the phase locking process is not a special phenomenon subject to the resistive boundary condition, but a common feature of the MHD relaxation process in the RFP. The relation between the phase locking and MHD relaxation processes is briefly discussed. (author)
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
Analysis and test to predict the fatigue life of the ISX-B toroidal field coils' finger joints
International Nuclear Information System (INIS)
O'Toole, J.A.; Ojalvo, I.U.; Raynor, G.E.; Zatz, I.J.; Johnson, N.E.; Walls, J.C.; Nelson, B.E.; Cain, W.D.; Walstrom, P.L.; Pearce, J.W.
1979-01-01
A new and more rigorous structural evaluation of the ISX toroidal field (TF) coil fingers joints was undertaken to assess the effects of high-/beta/ operation of ISX-B. A new poloidal field (PF) coil set which allows high-/beta/ operation and produces larger out-of-plane loads on the TF coils was installed as part of the change to ISX-B. It was determined that the iron core significantly affects the out-of-plane load distribution and forces were calculated using the GFUN-3D code which considers 3-D iron core effects. These loads were applied to a half-symmetric finite element NASTRAN code model in which the TF coils were modeled as a string of beam elements. 8 refs
Topological currents in neutron stars: kicks, precession, toroidal fields, and magnetic helicity
International Nuclear Information System (INIS)
Charbonneau, James; Zhitnitsky, Ariel
2010-01-01
The effects of anomalies in high density QCD are striking. We consider a direct application of one of these effects, namely topological currents, on the physics of neutron stars. All the elements required for topological currents are present in neutron stars: degenerate matter, large magnetic fields, and parity violating processes. These conditions lead to the creation of vector currents capable of carrying momentum and inducing magnetic fields. We estimate the size of these currents for many representative states of dense matter in the neutron star and argue that they could be responsible for the large proper motion of neutron stars (kicks), the toroidal magnetic field and finite magnetic helicity needed for stability of the poloidal field, and the resolution of the conflict between type-II superconductivity and precession. Though these observational effects appear unrelated, they likely originate from the same physics — they are all P-odd phenomena that stem from a topological current generated by parity violation
Evaluation of mechanical strength of the joints in JT-60 toroidal field coil conductors
Nishio, S.; Ohkubo, M.; Sasajima, H.
1980-04-01
Toroidal field (TF) coils of JT-60 produce a toroidal field of 45 KG at a plasma axis, they have an inner bore of 3.90 m and a weight of about 80 metric tons per coil. Eighteen TF coils are located around a torus axis at regular intervals. TF coil conductors are mostly jointed by high frequency induction brazing, the rest jointed by welding. In deciding the details of the jointing procedures, the conductor size and the requested mechanical strength are mainly taken into consideration. Described are non-destructive inspection methods for the brazed joints, strength evaluation, and the inspection criteria. Ultrasonic testing method is found to be the most effective in evaluation of mechanical properties of the brazed joints especially in terms of fatigue strength. The ultrasonic inspection method and the detectability of this apparatus are described in detail, and the defects of known size are compared with the indication values and display figures. The apparatus developed for JT-60 is operated automatically also recording the inspection results. Mechanical strength of the brazed joints with initial defects is discussed.
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)
Energy Technology Data Exchange (ETDEWEB)
Flanagan, C.A. (ed.)
1984-10-01
This document is a design overview that describes the scoping studies and preconceptual design effort performed in FY 1983 on the Tokamak Fusion Core Experiment (TFCX) class of device. These studies focussed on devices with all-superconducting toroidal field (TF) coils and on devices with superconducting TF coils supplemented with copper TF coil inserts located in the bore of the TF coils in the shield region. Each class of device is designed to satisfy the mission of ignition and long pulse equilibrium burn. Typical design parameters are: major radius = 3.75 m, minor radius = 1.0 m, field on axis = 4.5 T, plasma current = 7.0 MA. These designs relay on lower hybrid (LHRH) current rampup and heating to ignition using ion cyclotron range of frequency (ICRF). A pumped limiter has been assumed for impurity control. The present document is a design overview; a more detailed design description is contained in a companion document.
A code for calculating force and temperature of a bitter plate type toroidal field coil system
International Nuclear Information System (INIS)
Christensen, U.
1989-01-01
To assist the design effort of the TF coils for CIT, a set of programs was developed to calculate the transient spatial distribution of the current density, the temperature and the forces in the TF coil conductor region. The TF coils are of the Bitter (disk) type design and therefore have negligible variation of current density in the toroidal direction. During the TF pulse, voltages are induced which cause the field and current to diffuse in the minor radial direction. This penetration, combined with the increase of resistance due to the temperature rise determines the distribution of the current. After the current distribution has been determined, the in-plane (TF-TF) and the out-of-plane (TF-PF) forces in the conductor are computed. The predicted currents and temperatures have been independently corroborated using the SPARK code which has been modified for this type of problem. 6 figs
Two preliminary alternative designs for the gravity support of ITER toroidal field magnet
International Nuclear Information System (INIS)
Hou Binglin; Pan Chuanhong; Li Pengyuan; Zhang Nianman
2009-01-01
According to the original reference design, the gravity support pedestal (GSP) of ITER toroidal field magnet will be very difficult to fabricate because of large vacuum electronic welding, and therefore, two conceptual alternative designs, 'split vacuum electronic welding option' and 'bolt clamping option', are put forward. The preliminary buckling analyses with FEM (finite element method) and hand calculation show that there are enough safety margin in two options and both of them are feasible. Even though the 'split vacuum electronic welding option' makes the welding easier (in which GSP is split into two halves and thereby no large vacuum-chamber is needed), there are more advantages in the 'bolt clamping option' (where no welding is needed), such as the GSP fabrication is simple, the reject rate is low, the cost is much lower, and the producing time is shortened. Comparably, the 'bolt clamping option' is strongly recommended. (authors)
Effects of toroidal field ripple on suprathermal ions in tokamak plasmas
International Nuclear Information System (INIS)
Goldston, R.J.; Towner, H.H.
1980-02-01
Analytic calculations of three important effects of toroidal field ripple on suprathermal ions in tokamak plasmas are presented. In the first process, collisional ripple-trapping, beam ions become trapped in local magnetic wells near their banana tips due to pitch-angle scattering as they traverse the ripple on barely unripple-trapped orbits. In the second process, collisionless ripple-trapping, near-perpendicular untrapped ions are captured (again near a banana tip) due to their finite orbits, which carry them out into regions of higher ripple. In the third process, banana-drift diffusion, fast-ion banana orbits fail to close precisely, due to a ripple-induced variable lingering period near the banana tips. These three mechanisms lead to substantial radial transport of banana-trapped, neutral-beam-injected ions when the quantity α* identical with epsilon/sin theta/Nqdelta is of order unity or smaller
Effects of toroidal field ripple on suprathermal ions in tokamak plasmas
International Nuclear Information System (INIS)
Goldston, R.J.; Towner, H.H.
1981-01-01
Analytic calculations of three important effects of toroidal field ripple on suprathermal ions in tokamak plasmas are presented. In the first process, collisional ripple-trapping, ions become trapped in local magnetic wells near their banana tips owing to pitch-angle scattering as they traverse the ripple on barely unripple-trapped orbits. In the second process, collisionless ripple-trapping, ions are captured (again near a banana tip) owing to their finite orbits, which carry them out into regions of higher ripple. In the third process, banana-drift diffusion, fast-ion banana orbits fail to close precisely, due to a ripple-induced 'variable lingering period' near the banana tips. These three mechanisms lead to substantial radial transport of banana-trapped, neutral-beam-injected ions when the quantity α* is identical with epsilonsinthetaNqdelta is of order unity or smaller. (author)
Thermal analysis of toroidal field coil in EAST at 3.7 K
International Nuclear Information System (INIS)
Yi, Shi; Wu, Yu; Liu, Bo.; Long, Feng; Hao, Qiang W.
2014-01-01
Highlights: • In this study, the thermal performance of toroidal field (TF) coil is studied at 3.7 K in Experimental Advanced Superconducting Tokamak device (EAST) to obtain the higher stability. • The structure and cooling process design of TF coil and case is described and the helium temperature in the cable-in-conduit conductor (CICC) and case is evaluated during the 1.5 MA plasma disruptions. • Then, the experimental results of TF coil cooled at 3.7 K and discharged in 10 kA are shown including the thermal loss evaluation. • Finally, the thermal stability performance of TF coil is analyzed at 1.5 MA plasma current operations. - Abstract: The thermal performance of toroidal field (TF) coil is studied at 3.7 K in Experimental Advanced Superconducting Tokamak device (EAST) to obtain the higher stability for the higher plasma parameters operation. It is a good way to lower the operating temperature of TF coil to acquire the higher stability margin. This paper describes the structure and cooling process design of TF coil and case firstly. Based on the thermal load in the case, the thermal performance of the TF coil is performed at the plasma disruption state. The helium temperature in the cable-in-conduit conductor (CICC) and case is evaluated during the 1.5 MA plasma disruptions. Then, the experimental results of TF coil which has been cooled at 3.7 K and discharged in 10 kA are shown including the thermal loss evaluation. Finally, the thermal stability performance of TF coil is analyzed according to the 3.7 K experimental results and the stability prediction is performed at 1.5 MA plasma current operations
Investigation of a Hybrid Winding Concept for Toroidal Inductors using 3D Finite Element Modeling
DEFF Research Database (Denmark)
Schneider, Henrik; Andersen, Thomas; Mønster, Jakob Døllner
2013-01-01
This paper investigates a hybrid winding concept for a toroidal inductor by simulating the winding resistance as a function of frequency. The problem of predicting the resistance of a non-uniform and complex winding shape is solved using 3D Finite Element Modeling. A prototype is built and tested...
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, Paulo; Bizarro, Joao P. S. [Associacao Euratom-IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, 1049-001 Lisboa (Portugal)
2013-04-15
The axisymmetry condition and two of Maxwell's equations are used to show that, in general, there are no nested magnetic surfaces around a poloidal-magnetic-field null for a sufficiently small value of the toroidal current density flowing there. Hence, the toroidal current density at the axis of a magnetic configuration with extreme shear reversal cannot continuously approach zero unless nested surfaces are first broken or particular values are assigned to boundary conditions and other plasma parameters. The threshold of the toroidal current-density at which the topology changes is shown to be set by such parameters, and some examples of the predicted topology transition are presented using analytical solutions of the Grad-Shafranov equation.
International Nuclear Information System (INIS)
Smith, B.R.
1995-01-01
This document identifies the candidate materials and manufacturing processes selected for development of the TPX Toroidal Field (TF) Magnet. Supporting rationale and selection criteria are provided for justification and the materials properties database report is included for completeness. Specific properties for each material selection are included in this document
Construction of force-free fields which have toroidal surfaces about a given surface
International Nuclear Information System (INIS)
Bouligand, G.
1983-05-01
A study of two-fields (B vector, rotB vector) of conservative flux which admits a family of toroidal surfaces of parameter phi on a domain limited by a given surface S, suggests their construction by a Cauchy-Arzela method of step by step. Taking into account the Newcomb condition this method is consistent with force-free magnetic fields and with helical equilibria with scalar pressure. The method supposes that B vector is of class C 1 . This construction makes use of the remarkable property of the field B vector to be the surface gradient of a generating multivalued function Q on a closed surface. Consequently, the initial surface will be given with its normal metric coefficient K; that is to say, B vector admits a family F of homotopic surfaces on a infinitesimal domain about S, an element of F. From this, the periodic part of Q is a solution of a Beltrami equation for the flux conservation of which numerical resolution is envisaged. The study of these fields is made in a biorthogonal system of coordinates. The coeffficients of the two fundamental metric forms of magnetic surfaces vary with phi and are interrelated by a sixth order differential system of equations which gives their variation [fr
International Nuclear Information System (INIS)
Chen Wenge; Pan Yannian; Chen Zuoming; Wei Jin
2008-01-01
The toroidal field (TF) magnet system of EAST (HT-7U), which consists of 16 superconducting coils enclosed in steel cases, has been manufactured to generate the magnetic field of 3.5 T at the plasma center to maintain plasma in a tokamak configuration with a current up to 1 MA. The TF coils have an approximately D-shape geometry of 2.6 m wide and 4.0 m high, and operate at a maximum field of 5.8 T. The conductor used in the TF coil is NbTi/Cu cable-in conduit (CIC) conductor, and its operating current is 14.3 kA. In March 2006, the first cooling down of the EAST device has been carried out successfully. The total of TF magnet system has been cooled down from room temperature to 4.5 K, and the TF system has been energized up to 8.2 kA with 5 A/s ramp rate. In September 2006, full performances of the TF magnet system have been reached, and the device of EAST has delivered its first plasma. In addition, the TF magnet system has been routinely operated with a current maintained constant on a whole day basis, for a preliminary program of more than 500 shots. In this paper, the main parts of the design, developmental tests, and the fabrication and assembly of TF coils are described in detail
Energy Technology Data Exchange (ETDEWEB)
Romadanov, I.V.; Ryzhkov, S.V., E-mail: ryzhkov@power.bmstu.ru
2014-12-15
Highlights: • Compact torus formation method with high level of magnetic flux is proposed. • A compact torus is produced in a theta-pinch-coil with pulse mode of operation. • Key feature is a pulse of current in an axial direction. • We report a level of linked magnetic flux is higher than theta-pinch results. - Abstract: The present work reports on compact toroid hydrogen plasma creation by means of a specially designed discharge system and results of magnetic fields introduction. Experiments in the compact toroid challenge (CTC) device at P.N. Lebedev Physical Institute (FIAN) have been conducted since 2005. The CTC device differs from the conventional theta-pinch formation in the use of an axial current for enhanced efficiency. We have used a novel technique to maximize the flux linked to the plasma. The purpose of this method is to increase the energy input into the plasma and the level of trapped magnetic flux using an additional toroidal magnetic field. A study of compact torus formation with axial and toroidal currents was done and a new method is proposed and implemented.
International Nuclear Information System (INIS)
McGann, M.; Hudson, S.R.; Dewar, R.L.; Nessi, G. von
2010-01-01
The vanishing of the divergence of the total stress tensor (magnetic plus kinetic) in a neighborhood of an equilibrium plasma containing a toroidal surface of discontinuity gives boundary and jump conditions that strongly constrain allowable continuations of the magnetic field across the surface. The boundary conditions allow the magnetic fields on either side of the discontinuity surface to be described by surface magnetic potentials, reducing the continuation problem to that of solving a Hamilton-Jacobi equation. The characteristics of this equation obey Hamiltonian equations of motion, and a necessary condition for the existence of a continued field across a general toroidal surface is that there exist invariant tori in the phase space of this Hamiltonian system. It is argued from the Birkhoff theorem that existence of such an invariant torus is also, in general, sufficient for continuation to be possible. An important corollary is that the rotational transform of the continued field on a surface of discontinuity must, generically, be irrational.
Energy Technology Data Exchange (ETDEWEB)
Bayer, Christoph M.
2017-05-01
Nuclear fusion is a key technology to satisfy the basic demand for electric energy sustainably. The official EUROfusion schedule foresees a first industrial DEMOnstration Fusion Power Plant for 2050. In this work several high temperature superconductor sub-size cables are investigated for their applicability in large scale DEMO toroidal field coils. Main focus lies on the electromechanical stability under the influence of high Lorentz forces at peak magnetic fields of up to 12 T.
Bayer, Christoph M
2017-01-01
Nuclear fusion is a key technology to satisfy the basic demand for electric energy sustainably. The official EUROfusion schedule foresees a first industrial DEMOnstration Fusion Power Plant for 2050. In this work several high temperature superconductor sub-size cables are investigated for their applicability in large scale DEMO toroidal field coils. Main focus lies on the electromechanical stability under the influence of high Lorentz forces at peak magnetic fields of up to 12 T.
Phase coexistence and electric-field control of toroidal order in oxide superlattices
International Nuclear Information System (INIS)
Damodaran, A. R.; Clarkson, J. D.; Hong, Z.
2017-01-01
Systems that exhibit phase competition, order parameter coexistence, and emergent order parameter topologies constitute a major part of modern condensed-matter physics. Here, by applying a range of characterization techniques, and simulations, we observe that in PbTiO 3 /SrTiO 3 superlattices all of these effects can be found. By exploring superlattice period-, temperature- and field-dependent evolution of these structures, we observe several new features. First, it is possible to engineer phase coexistence mediated by a first-order phase transition between an emergent, low-temperature vortex phase with electric toroidal order and a high-temperature ferroelectric a 1 /a 2 phase. At room temperature, the coexisting vortex and ferroelectric phases form a mesoscale, fibre-textured hierarchical superstructure. The vortex phase possesses an axial polarization, set by the net polarization of the surrounding ferroelectric domains, such that it possesses a multi-order-parameter state and belongs to a class of gyrotropic electrotoroidal compounds. Finally, application of electric fields to this mixed-phase system permits interconversion between the vortex and the ferroelectric phases concomitant with order-of-magnitude changes in piezoelectric and nonlinear optical responses. Here, our findings suggest new cross-coupled functionalities.
Mechanical design of the coils encapsulated of toroidal field of Tokamak TPM1
International Nuclear Information System (INIS)
Caldino H, U.; Francois L, J. L.
2014-10-01
The TPM1 is a small Tokamak that belongs to the Centro de Investigacion en Ciencias Aplicadas y Tecnologia Avanzada of Instituto Politecnico Nacional (CICATA-IPN); the project is under construction. Currently it has the vacuum chamber, and is intended that the machine can operate with electric pulses of 10 ms to study the behavior of plasmas in order to provide knowledge in the field of nuclear fusion by magnetic confinement. To achieve this goal is necessary to design the toroidal field coils which operate the Tokamak. This paper presents an analysis which was performed to obtain the correct configuration of coils depending on design parameters for operation of the machine. Once determined this configuration, an analysis of electromagnetic forces present in normal machine operation on one coil was conducted, this to know the stresses in the encapsulation of the same. Considering the pulsed operation, a thickness of 5 mm is determined in the encapsulated, considering fatigue failure based on studies of fatigue failures in epoxy resins. (Author)
Performance assessment and optimization of the ITER toroidal field coil joints
Rolando, G.; Foussat, A.; Knaster, J.; Ilin, Y.; Nijhuis, A.
2013-08-01
The ITER toroidal field (TF) system features eighteen coils that will provide the magnetic field necessary to confine the plasma. Each winding pack is composed of seven double pancakes (DP) connected through praying hands joints. Shaking hands joints are used to interface the terminals of the conductor with the feeder and inter-coil U-shaped bus bars. The feasibility of operating plasma scenarios depends on the ability of the magnets to retain sufficient temperature and current margins. In this respect, the joints represent a possible critical region due to the combination of steady state Joule heating in the resistance of the joint and coupling losses and currents in ramped operation. The temperature and current margins of both DP and terminal joints are analysed during the 15 and 17 MA plasma scenarios. The effect on the joint performance of feasible optimization solutions, such as rotation of the terminal joints and sole RRR increase, is explored. The characterization of the TF coil joints is completed by the estimation of the coupling loss time constant for different inter-strand and strand-to-joint resistance values. The study is carried out with the code JackPot-ACDC, allowing the analysis of lap-type joints with a strand-level detail.
Fabrication of Nb3Sn cables for ITER toroidal field coils
International Nuclear Information System (INIS)
Isono, Takaaki; Tsutsumi, Fumiaki; Nunoya, Yoshihiko; Matsui, Kunihiro; Takahashi, Yoshikazu; Nakajima, Hideo; Ishibashi, Tatsuji; Sato, Go; Chida, Kenji; Suzuki, Rikio; Tanji, Tsutomu
2012-01-01
Cable-in-conduit conductors for ITER toroidal field (TF) coils will be operated at 68 kA and 11.8 T. The cable is composed of 1,422 strands with a diameter of 0.82 mm. There were two options for initial procurement. For option 2, the twist pitches at lower stages are longer than in option 1. Trials were performed to assess the feasibility of these options. In the trials for option 1, the nominal outer diameter of sub-cables and reduction schedule of final cables were evaluated and finalized. In the trials for option 2, problems were encountered at the third stage cabling. These problems were resolved through increasing the die size in that stage and improving the tension balance of the second-stage cables to reduce friction between the die and the cable, and also through avoiding loose twisting at both edges of the third cables. Option 2 was finally selected in 2009 based on superconducting performance enhancement of the cable. After the qualification of the fabrication procedure using fabrication of a 760-m dummy cable and a 415-m superconducting cable, mass production of the cables started in March 2010. (author)
Status of European manufacture of Toroidal Field conductor and strand for JT-60SA project
International Nuclear Information System (INIS)
Zani, Louis; Barabaschi, Pietro; Di Pietro, Enrico
2013-01-01
In the framework of the JT-60SA project, part of the Broader Approach (BA) agreement, EURATOM provides to Japan, the Toroidal Field (TF) magnet system, consisting of 18 superconducting coils. The procurement of the conductor for the TF coils is managed by Fusion for Energy, acting as EU representative in the BA agreement. The TF conductor procurement is split into two contracts, one dedicated to the production of Niobium Titanium (NbTi) and Cu strand and the other to TF conductor production through strand cabling and cable jacketing operations. The TF conductor is a rectangular-shaped cable-in-conduit conductor formed by 486 (0.81 mm diameter) strands (2/3 NbTi–1/3 Cu) wrapped in a stainless steel foil and embedded into a stainless steel jacket. The 18 TF coils require (including spares) 115 ‘Unit Lengths’ (UL) of such conductor, each 240 m long for a total of about 28 km. Correspondingly about 10,000 km for NbTi and 5000 km for Cu strand are produced. The Japanese company Furukawa Electric Co. (FEC) is in charge of TF strand manufacture while the Italian company Italian Consortium for Applied Superconductivity (ICAS) is in charge of cabling and jacketing of TF conductor ULs. In the paper, we provide information on the production stages presently achieved in TF strand and conductor contracts
Irradiation and testing of compact ignition tokamak toroidal field coil insulation materials
International Nuclear Information System (INIS)
Kanemoto, G.K.; Sherick, M.J.; Sparks, D.C.
1990-05-01
This report documents the results of an irradiation and testing program performed on behalf of Martin Marietta Energy Systems, Inc. in support of the Compact Ignition Tokamak Research and Development program. The purpose of the irradiation and testing program was to determine the effects of neutron and gamma irradiation on the mechanical and electrical properties of candidate toroidal field coil insulation materials. Insulation samples were irradiated in the Advanced Test Reactor (ATR) in a large I-hole. The insulation samples were irradiated within a lead shield to reduce exposure to gamma radiation to better approximate the desired ration of neutron to gamma exposure. Two different exposure levels were specified for the insulation samples. To accomplish this, the samples were encapsulated in two separate aluminum capsules; the capsules positioned at the ATR core mid-plane and at the top of the fueled region to take advantage of the axial cosine distribution of the neutron and gamma flux; and by varying the length of irradiation time of the two capsules. Disassembly of the irradiated capsules and testing of the insulation samples were performed at the Test Reactor Area (TRA) Hot Cell Facilities. Testing of the samples included shear compression static, shear compression fatigue, flexure static, and electrical resistance measurements
Energy Technology Data Exchange (ETDEWEB)
Caldino H, U.; Francois L, J. L., E-mail: ucaldino@outlook.com [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac 8532, 62550 Jiutepec, Morelos (Mexico)
2014-10-15
The TPM1 is a small Tokamak that belongs to the Centro de Investigacion en Ciencias Aplicadas y Tecnologia Avanzada of Instituto Politecnico Nacional (CICATA-IPN); the project is under construction. Currently it has the vacuum chamber, and is intended that the machine can operate with electric pulses of 10 ms to study the behavior of plasmas in order to provide knowledge in the field of nuclear fusion by magnetic confinement. To achieve this goal is necessary to design the toroidal field coils which operate the Tokamak. This paper presents an analysis which was performed to obtain the correct configuration of coils depending on design parameters for operation of the machine. Once determined this configuration, an analysis of electromagnetic forces present in normal machine operation on one coil was conducted, this to know the stresses in the encapsulation of the same. Considering the pulsed operation, a thickness of 5 mm is determined in the encapsulated, considering fatigue failure based on studies of fatigue failures in epoxy resins. (Author)
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
Cryogenic aspects of a demountable toroidal field magnet system for tokamak type fusion reactors
International Nuclear Information System (INIS)
Hsieh, S.Y.; Powell, J.; Lehner, J.
1977-01-01
A new concept for superconducting Toroidal Field (TF) magnet construction is presented. It is termed the ''Demountable Externally Anchored Low Stress'' (DEALS) magnet system. In contrast to continuous wound conventional superconducting coils, each magnet coil is made from several straight coil segments to form a polygon which can be joined and disjoined to improve reactor maintenance accessibility or to replace failed coil segments if necessary. A design example is presented of a DEALS magnet system for a UWMAK II size reactor. The overall magnet system is described, followed by a detailed analysis of the major heat loads in order to assess the refrigeration requirements for the concept. Despite the increased heat loads caused by high current power leads (200,000 amps) and the coil warm reinforcement support system, the analysis shows that at most, only about one percent (approximately 20 Mw) of the plant electrical output (approximately 2,000 Mw) is needed to operate the magnet cryogenic system. The advantages and the drawbacks of the DEALS magnet system are also discussed. The advantages include: capability to replace failed coils, increased accessibility to the blanket shield assembly, reduced reliability requirements for the magnet, much lower stress in conductor, easier application of improved high field brittle superconductors like Nb 3 Sn, improved magnet safety features, etc. The drawbacks are the increased refrigeration requirements and the necessity of a movable coil support system. A comparison with a conventional magnet system is made. It is concluded that the benefits of the DEALS approach far outweigh its penalties, and that the DEALS concept is the most practical, economical way to construct TF magnet systems for Tokamak reactors
Rista, P. E. C.; Shull, J.; Sargent, S.
2015-12-01
The ITER cryodistribution system provides the supercritical Helium (SHe) forced flow cooling to the magnet system using cold circulators. The cold circulators are located in each of five separate auxiliary cold boxes planned for use in the facility. Barber-Nichols Inc. has been awarded a contract from ITER-India for engineering, manufacture and testing of the Toroidal Field (TF) Magnet Helium Cold Circulator. The cold circulator will be extensively tested at Barber-Nichols’ facility prior to delivery for qualification testing at the Japan Atomic Energy Agency's (JAEA) test facility at Naka, Japan. The TF Cold Circulator integrates features and technical requirements which Barber-Nichols has utilized when supplying helium cold circulators worldwide over a period of 35 years. Features include a vacuum-jacketed hermetically sealed design with a very low helium leak rate, a heat shield for use with both nitrogen & helium cold sources, a broad operating range with a guaranteed isentropic efficiency over 70%, and impeller design features for high efficiency. The cold circulator will be designed to meet MTBM of 17,500 hours and MTBF of 36,000 hours. Vibration and speed monitoring are integrated into a compact package on the rotating assembly with operation and health monitoring in a multi-drop PROFIBUS communication environment using an electrical cabinet with critical features and full local and network PLC interface and control. For the testing in Japan and eventual installation in Europe, the cold circulator must be certified to the Japanese High Pressure Gas Safety Act (JHPGSA) and CE marked in compliance with the European Pressure Equipment Directive (PED) including Essential Safety Requirements (ESR). The test methodology utilized at Barber-Nichols’ facility and the resulting test data, validating the high efficiency of the TF Cold Circulator across a broad operating range, are important features of this paper.
International Nuclear Information System (INIS)
C Rista, P E; Shull, J; Sargent, S
2015-01-01
The ITER cryodistribution system provides the supercritical Helium (SHe) forced flow cooling to the magnet system using cold circulators. The cold circulators are located in each of five separate auxiliary cold boxes planned for use in the facility. Barber-Nichols Inc. has been awarded a contract from ITER-India for engineering, manufacture and testing of the Toroidal Field (TF) Magnet Helium Cold Circulator. The cold circulator will be extensively tested at Barber-Nichols’ facility prior to delivery for qualification testing at the Japan Atomic Energy Agency's (JAEA) test facility at Naka, Japan. The TF Cold Circulator integrates features and technical requirements which Barber-Nichols has utilized when supplying helium cold circulators worldwide over a period of 35 years. Features include a vacuum-jacketed hermetically sealed design with a very low helium leak rate, a heat shield for use with both nitrogen and helium cold sources, a broad operating range with a guaranteed isentropic efficiency over 70%, and impeller design features for high efficiency. The cold circulator will be designed to meet MTBM of 17,500 hours and MTBF of 36,000 hours. Vibration and speed monitoring are integrated into a compact package on the rotating assembly with operation and health monitoring in a multi-drop PROFIBUS communication environment using an electrical cabinet with critical features and full local and network PLC interface and control. For the testing in Japan and eventual installation in Europe, the cold circulator must be certified to the Japanese High Pressure Gas Safety Act (JHPGSA) and CE marked in compliance with the European Pressure Equipment Directive (PED) including Essential Safety Requirements (ESR). The test methodology utilized at Barber-Nichols’ facility and the resulting test data, validating the high efficiency of the TF Cold Circulator across a broad operating range, are important features of this paper. (paper)
Energy measurement of fast ions trapped in the toroidal field ripple of Tore Supra
International Nuclear Information System (INIS)
Basiuk, V.; Becoulet, A.; Hutter, T.; Martin, G.; Pecquet, A.L.; Saoutic, B.
1993-09-01
During additional heating in Tore Supra (ICRF or NBI) fast ion losses due to the toroidal field ripple were clearly measured by a set of graphite probes. This diagnostic collects the flow of fast ions entering a vertical port and usually shows a maximum flux for ions originating from the vicinity of surface δ * = 0. During the monster sawteeth regime, achieved with ICRF, a remarkable phenomenon was observed: the ejection of fast ions, not correlated with any measured MHD activity. The radial distribution of these ions is quite different from that usually observed exhibiting a peak located in the central section of the plasma. In order to measure the energy distribution of these ions, from 80 keV (energy of the neutral beam injected in Tore Supra) up to 1 MeV (expected during ICRF), a new diagnostic is under construction. The principle of the diagnostic is to discriminate the ions in energy using their Larmor radius (p = 1.3 cm for 100 keV → p = 3.6 cm for 700 keV, B = 4T). The detector is made of a hollow graphite cylinder with a small entrance slot, located in a vertical port on the ion drift side. An array of six metallic collectors placed inside the graphite cylinder intercepts the ions. The current on each collector was estimated at 10 → 100 nA, during ICRF heating. The energy resolution of this diagnostic is expected to be about 20 keV for the lowest energy range and 100 keV for the highest. This type of ruggedized detector might be extrapolated for the measurements of alpha particle losses in future DT experiments. It should also be suitable for the studies of stochastic ripple diffusion. (authors). 3 refs., 9 figs
Compact toroid injection fueling in a large field-reversed configuration
Asai, T.; Matsumoto, T.; Roche, T.; Allfrey, I.; Gota, H.; Sekiguchi, J.; Edo, T.; Garate, E.; Takahashi, Ts.; Binderbauer, M.; Tajima, T.
2017-07-01
A repetitively driven compact toroid (CT) injector has been developed for the large field-reversed configuration (FRC) facility of the C-2/C-2U, primarily for particle refueling. A CT is formed and injected by a magnetized coaxial plasma gun (MCPG) exclusively developed for the C-2/C-2U FRC. To refuel the particles of long-lived FRCs, multiple CT injections are required. Thus, a multi-stage discharge circuit was developed for a multi-pulsed CT injection. The drive frequency of this system can be adjusted up to 1 kHz and the number of CT shots per injector is two; the system can be further upgraded for a larger number of injection pulses. The developed MCPG can achieve a supersonic ejection velocity in the range of ~100 km s-1. The key plasma parameters of electron density, electron temperature and the number of particles are ~5 × 1021 m-3, ~30 eV and 0.5-1.0 × 1019, respectively. In this project, single- and double-pulsed counter CT injection fueling were conducted on the C-2/C-2U facility by two CT injectors. The CT injectors were mounted 1 m apart in the vicinity of the mid-plane. To avoid disruptive perturbation on the FRC, the CT injectors were operated at the lower limit of the particle inventory. The experiments demonstrated successful refueling with a significant density build-up of 20-30% of the FRC particle inventory per single CT injection without any deleterious effects on the C-2/C-2U FRC.
International Nuclear Information System (INIS)
Zhang, Xuan; Zikanov, Oleg
2017-01-01
Highlights: • 2D convection flow develops with internal heating and strong axial magnetic field. • Poloidal magnetic field suppresses turbulence at high Hartmann number. • Flow structure is dominated by large-scale counter-rotation vortices. • Effective heat transfer is maintained by surviving convection structures. - Abstract: We explore the effect of poloidal magnetic field on the thermal convection flow in a toroidal duct of a generic liquid metal blanket. Non-uniform strong heating (the Grashof number up to 10 11 ) arising from the interaction of high-speed neutrons with the liquid breeder, and strong magnetic field (the Hartmann number up to 10 4 ) corresponding to the realistic reactor conditions are considered. The study continues our earlier work , where the problem was solved for a purely toroidal magnetic field and the convection was found to result in two-dimensional turbulence and strong mixing within the duct. Here, we find that the poloidal component of the magnetic field suppresses turbulence, reduces the flow's kinetic energy and high-amplitude temperature fluctuations, and, at high values of Hartmann number, leads to a steady-state flow. At the same time, the intense mixing by the surviving convection structures remains able to maintain effective heat transfer between the liquid metal and the walls.
Statistical analysis of the Nb3Sn strand production for the ITER toroidal field coils
Vostner, A.; Jewell, M.; Pong, I.; Sullivan, N.; Devred, A.; Bessette, D.; Bevillard, G.; Mitchell, N.; Romano, G.; Zhou, C.
2017-04-01
The ITER toroidal field (TF) strand procurement initiated the largest Nb3Sn superconducting strand production hitherto. The industrial-scale production started in Japan in 2008 and finished in summer 2015. Six ITER partners (so-called Domestic Agencies, or DAs) are in charge of the procurement and involved eight different strand suppliers all over the world, of which four are using the bronze route (BR) process and four the internal-tin (IT) process. In total more than 500 tons have been produced including excess material covering losses during the conductor manufacturing process, in particular the cabling. The procurement is based on a functional specification where the main strand requirements like critical current, hysteresis losses, Cu ratio and residual resistance ratio are specified but not the strand production process or layout. This paper presents the analysis on the data acquired during the quality control (QC) process that was carried out to ensure the same conductor performance requirements are met by the different strand suppliers regardless of strand design. The strand QC is based on 100% billet testing and on applying statistical process control (SPC) limits. Throughout the production, samples adjacent to the strand pieces tested by the suppliers are cross-checked (‘verified’) by their respective DAs reference labs. The level of verification was lowered from 100% at the beginning of the procurement progressively to approximately 25% during the final phase of production. Based on the complete dataset of the TF strand production, an analysis of the SPC limits of the critical strand parameters is made and the related process capability indices are calculated. In view of the large-scale production and costs, key manufacturing parameters such as billet yield, number of breakages and piece-length distribution are also discussed. The results are compared among all the strand suppliers, focusing on the difference between BR and IT processes. Following
Little strings, quasi-topological sigma model on loop group, and toroidal Lie algebras
Ashwinkumar, Meer; Cao, Jingnan; Luo, Yuan; Tan, Meng-Chwan; Zhao, Qin
2018-03-01
We study the ground states and left-excited states of the Ak-1 N = (2 , 0) little string theory. Via a theorem by Atiyah [1], these sectors can be captured by a supersymmetric nonlinear sigma model on CP1 with target space the based loop group of SU (k). The ground states, described by L2-cohomology classes, form modules over an affine Lie algebra, while the left-excited states, described by chiral differential operators, form modules over a toroidal Lie algebra. We also apply our results to analyze the 1/2 and 1/4 BPS sectors of the M5-brane worldvolume theory.
Little strings, quasi-topological sigma model on loop group, and toroidal Lie algebras
Directory of Open Access Journals (Sweden)
Meer Ashwinkumar
2018-03-01
Full Text Available We study the ground states and left-excited states of the Ak−1 N=(2,0 little string theory. Via a theorem by Atiyah [1], these sectors can be captured by a supersymmetric nonlinear sigma model on CP1 with target space the based loop group of SU(k. The ground states, described by L2-cohomology classes, form modules over an affine Lie algebra, while the left-excited states, described by chiral differential operators, form modules over a toroidal Lie algebra. We also apply our results to analyze the 1/2 and 1/4 BPS sectors of the M5-brane worldvolume theory.
Theoretical study of structure of electric field in helical toroidal plasmas
International Nuclear Information System (INIS)
Toda, S.; Itoh, K.
2001-06-01
A set of transport equations is analyzed, including the bifurcation of the electric field. The structure of the electric field is studied by use of the theoretical model for the anomalous transport diffusivities. The steep gradient of the electric field is obtained at the electric domain. The suppression of the anomalous transport diffusivity is studied in the presence of the strong shear of the electric field. The hard transition with the multiple ambipolar solutions is examined in the structure of the radial electric field. The details of the structure of the electric domain interface are investigated. (author)
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.
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.
The implementation of a toroidal limiter model into the gyrokinetic code ELMFIRE
Energy Technology Data Exchange (ETDEWEB)
Leerink, S.; Janhunen, S.J.; Kiviniemi, T.P.; Nora, M. [Euratom-Tekes Association, Helsinki University of Technology (Finland); Heikkinen, J.A. [Euratom-Tekes Association, VTT, P.O. Box 1000, FI-02044 VTT (Finland); Ogando, F. [Universidad Nacional de Educacion a Distancia, Madrid (Spain)
2008-03-15
The ELMFIRE full nonlinear gyrokinetic simulation code has been developed for calculations of plasma evolution and dynamics of turbulence in tokamak geometry. The code is applicable for calculations of strong perturbations in particle distribution function, rapid transients and steep gradients in plasma. Benchmarking against experimental reflectometry data from the FT2 tokamak is being discussed and in this paper a model for comparison and studying poloidal velocity is presented. To make the ELMFIRE code suitable for scrape-off layer simulations a simplified toroidal limiter model has been implemented. The model is be discussed and first results are presented. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
18–22 cm VLBA Observational Evidence for Toroidal B-Field Components in Six AGN Jets
Directory of Open Access Journals (Sweden)
Juliana Cristina Motter
2016-08-01
Full Text Available The formation of relativistic jets in Active Galactic Nuclei (AGN is related to accretion onto their central supermassive black holes, and magnetic (B fields are believed to play a central role in launching, collimating, and accelerating the jet streams from very compact regions out to kiloparsec scales. We present results of Faraday rotation studies based on Very Long Baseline Array (VLBA data obtained at 18–22 cm for six well known AGN (OJ 287, 3C 279, PKS 1510-089, 3C 345, BL Lac, and 3C 454.3, which probe projected distances out to tens of parsecs from the observed cores. We have identified statistically significant, monotonic, transverse Faraday rotation gradients across the jets of all but one of these sources, indicating the presence of toroidal B fields, which may be one component of helical B fields associated with these AGN jets.
Compact-Toroid Fusion Reactor (CTOR) based on the Field-Reversed Theta Pinch
International Nuclear Information System (INIS)
Hagenson, R.L.; Krakowski, R.A.
1981-01-01
Scoping studies of a translating Compact Torus Reactor (CTOR) have been made on the basis of a dynamic plasma model and an overall systems approach. This CTOR embodiment uses a Field-Reversed Theta Pinch as a plasma source. The field-reversed plasmoid would be formed and compressionally heated to ignition prior to injection into and translation through a linear burn chamber, thereby removing the high-technology plamoid source from the hostile reactor environment. Stabilization of the field-reversed plasmoid would be provided by a passive conducting shell located outside the high-temperature blanket but within the low-field superconducting magnets and associated radition shielding. On the basis of this batch-burn but thermally steady-state approach, a reactor concept emerges with a length below approx. 40 m that generates 300 to 400 MWe of net electrical power with a recirculating power fraction less than 0.15
International Nuclear Information System (INIS)
Kerns, J.A.; Slack, D.S.; Miller, J.R.
1987-01-01
The Tokamak Ignition/Burn Experimental Reactor (TIBER) is being designed to provide nuclear testing capabilities for first wall and blanket design concepts. The baseline design for TIBER II is to provide steady-state nuclear burn capabilities. These objectives must be met using reactor relevant components, such as state-of-the-art current drive schemes coupled with superconducting toroidal field (TF) and poloidal field (PF) coils. The design is also constrained to be cost effective, which forces the machine to be as small as possible. This last constraint limits the nuclear shielding in TIBER. Therefore, the TF coils will have a high nuclear heat load of up to 4.5 kW per coil. The cooling scheme and the thermal analysis for this design are presented
International Nuclear Information System (INIS)
Lee, V.D.
1987-01-01
The Fusion Engineering Design Center (FEDC) is part of a national design team that is developing the conceptual design of the Compact Ignition Tokamak (CIT). To achieve a compact device with the minimum major radius, a vertical preload system is being developed to react the vertical separating force normally carried by the inboard leg of the toroidal field (TF) coils. The preload system is in the form of a hydraulic press. Challenges in the design include the development of hydraulic and structural systems for very large force requirements, which could interface with the CIT machine, while allowing maximum access to the top, bottom, and radial periphery of the machine. Maximum access is necessary for maintenance, diagnostics, instrumentation, and control systems. Materials used in the design must function in the nuclear environment and in the presence of high magnetic fields. This paper presents the configuration development of the hydraulic press used to vertically preload the CIT device
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
Evidence for a toroidal magnetic-field component in 5C 4.114 on kiloparsec scales
Gabuzda, Denise C.; Knuettel, Sebastian; Bonafede, Annalisa
2015-11-01
Context. A monotonic, statistically significant gradient in the observed Faraday rotation measure (RM) across the jet of an active galactic nucleus (AGN) reflects a corresponding gradient in the electron density and/or line-of-sight magnetic (B) field in the region of Faraday rotation. For this reason, such gradients may indicate the presence of a toroidal B field component, possibly associated with a helical jet B field. Although transverse RM gradients have been reported across a number of parsec-scale AGN jets, the same is not true on kiloparsec scales, suggesting that other (e.g. random) magnetic-field components usually dominate on these larger scales. Aims: We wished to identify clear candidates for monotonic, transverse RM gradients across AGN jet and lobe structures on scales larger than those probed thus far, and estimate their statistical significances. Methods: We identified an extended, monotonic transverse Faraday-rotation gradient across the northern lobe of a previously published Very Large Array (kiloparsec-scale) RM image of 5C 4.114. We reanalyzed these VLA data in order to determine the significance of this RM gradient. Results: The RM gradient across the northern kiloparsec-scale lobe structure of 5C 4.114 has a statistical significance of about 4σ. There is also a somewhat less prominent monotonic transverse Faraday-rotation gradient across the southern jet/lobe (narrower range of distances from the core, significance ≃ 3σ). Other parts of the Faraday-rotation distribution observed across the source are patchy and show no obvious order. Conclusions: This suggests that we are observing a random RM component associated with the foreground material in the cluster in which the radio source is located and through which it is viewed, superposed on a more ordered RM component that arises in the immediate vicinity of the AGN jets. We interpret the transverse RM gradient as reflecting the systematic variations of the line-of-sight component of a
Matsumoto, T; Sekiguchi, J; Asai, T; Gota, H; Garate, E; Allfrey, I; Valentine, T; Morehouse, M; Roche, T; Kinley, J; Aefsky, S; Cordero, M; Waggoner, W; Binderbauer, M; Tajima, T
2016-05-01
A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10(21) m(-3), ∼40 eV, and 0.5-1.0 × 10(19), respectively.
Energy Technology Data Exchange (ETDEWEB)
Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T. [College of Science and Technology, Nihon University, 1-8-14 Kanda, Chiyoda-ku, Tokyo 1018308 (Japan); Gota, H.; Garate, E.; Allfrey, I.; Valentine, T.; Morehouse, M.; Roche, T.; Kinley, J.; Aefsky, S.; Cordero, M.; Waggoner, W.; Binderbauer, M. [Tri Alpha Energy, Inc., P.O. Box 7010 Rancho Santa Margarita, California 92688 (United States); Tajima, T. [Tri Alpha Energy, Inc., P.O. Box 7010 Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)
2016-05-15
A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10{sup 21} m{sup −3}, ∼40 eV, and 0.5–1.0 × 10{sup 19}, respectively.
International Nuclear Information System (INIS)
Roccella, M.; Marin, A.; Lucca, F.; Merola, M.
2008-01-01
A detailed evaluation of the EM loads in the ITER divertor during plasma disruptions is mandatory for the correct dimensioning of the divertor component. The EM loads during plasma disruptions are mainly produced by: (1) toroidal flux variation (TFV) during the thermal quench (TQ) and current quench (CQ); (2) halo currents (HC); and (3) poloidal flux variation (PFV) during TQ and CQ phase. The new ITER reference disruption and the last changes in the divertor design have been considered in the EM models created to calculate all the EM loads due to TFV, HC and PFV. All the analyses have been performed for the three different main design options of the divertor plasma facing units (PFU). The effects of PFV have been analyzed using an EM-zooming procedure that has allowed a good detail of the component model, while new numerical approaches have been developed for the evaluation of the effects due to TFV and HC maintaining the same detail for the divertor model. Separate models have been developed to evaluate the equivalent electrical resistivities of the various PFU options; this allows in the full 3D model a strong simplification of a geometry which would otherwise be very complex. The effect of an electrical surface bridging of the PFU castellation has also been taken into account
Lee, S H; Choe, W; Lee, T S
2002-01-01
Magnetic flux measurements of a toroidal magnet revealed a concave-shaped field distribution with a single minimum and a null field along the axis of the torus at the point where the field reversed. The non-linear magnetic field of the toroidal magnet perpendicular to the Ag sub 2 O-doped superconducting disc sample with trapped magnetic flux distorted the field line distribution. As a result, the interaction force between the magnet and the sample exhibited regions of repulsive, null, attractive, null and finally repulsive force. The asymmetrical concave-shaped force pattern along the axis with two null force points indicates that the force exerted on the sample changes direction, the transition from repulsive to attractive at the null force point, and the force becomes repulsive again beyond the second null force point as the distance along the axis increases. The magnetic field simulation using the Poisson numerical code for the toroidal magnet of 46 mm OD, 12 mm ID and 10 mm thickness was in close agreeme...
Modeling of Local Magnetic Field Enhancements within Solar Flux Ropes
Romashets, E; Vandas, M; Poedts, Stefaan
2010-01-01
To model and study local magnetic-field enhancements in a solar flux rope we consider the magnetic field in its interior as a superposition of two linear (constant alpha) force-free magnetic-field distributions, viz. a global one, which is locally similar to a part of the cylinder, and a local torus-shaped magnetic distribution. The newly derived solution for a toroid with an aspect ratio close to unity is applied. The symmetry axis of the toroid and that of the cylinder may or may not coinci...
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
Bercovici, David; Ricard, Yanick
2013-03-01
The grain-damage and pinning mechanism of Bercovici and Ricard (2012) for lithospheric shear-localization is employed in two-dimensional flow calculations to test its ability to generate toroidal (strike-slip) motion and influence plate evolution. This mechanism posits that damage to the interface between phases in a polycrystalline material like peridotite (composed primarily of olivine and pyroxene) increases the number of small Zener pinning surfaces, which then constrain mineral grains to ever smaller sizes, regardless of creep mechanism. This effect allows a self-softening feedback in which damage and grain-reduction can co-exist with a grain-size dependent diffusion creep rheology; moreover, grain growth and weak-zone healing are greatly impeded by Zener pinning thereby leading to long-lived relic weak zones. The fluid dynamical calculations employ source-sink driven flow as a proxy for convective poloidal flow (upwelling/downwelling and divergent/convergent motion), and the coupling of this flow with non-linear rheological mechanisms excites toroidal or strike-slip motion. The numerical experiments show that pure dislocation-creep rheology, and grain-damage without Zener pinning (as occurs in a single-phase assemblages) permit only weak localization and toroidal flow; however, the full grain-damage with pinning readily allows focussed localization and intense, plate-like toroidal motion and strike-slip deformation. Rapid plate motion changes are also tested with abrupt rotations of the source-sink field after a plate-like configuration is developed; the post-rotation flow and material property fields retain memory of the original configuration for extensive periods, leading to suboptimally aligned plate boundaries (e.g., strike-slip margins non-parallel to plate motion), oblique subduction, and highly localized, weak and long lived acute plate-boundary junctions such as at what is observed at the Aleutian-Kurile intersection. The grain-damage and pinning
Contributions to the design and to the fabrication of the magnet of the toroidal field of Tore Supra
International Nuclear Information System (INIS)
Turck, B.
1992-03-01
This report is a collection of published papers in French and in English about the design and the qualification of the magnet of the toroidal field of Tore Supra. The development test programme, the controls during conductor manufacturing and the acceptance tests have shown to be the bases for achieving a very low level of rejection for the whole production. A systematic study of the performances correlated to the fabrication conditions has provided valuable informations for the optimization of the manufacturing processes of superconductors. The tests of single coils have enabled the commissioning of a monitoring and protection system specially adapted for this magnet of 18 coils cooled in a superfluid helium bath. After the accident caused by an arcing in one coil of the Torus, and the replacement of the faulty coil, the monitoring and safety discharge system have been adapted. The current in the magnet has been increased up to 1 455 A for 9.3 T on the conductors (nominal values 1 400 A and 9 T). During the last three years (1989-1991) only one transition to normal state has been observed in one coil strongly irradiated after a severe plasma disruption. In these conditions the protection system acted very well and as expected
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
Xiong, Yuan
2017-05-02
This study presents an experimental work investigating the controlling parameters on the formation of an electrically-induced inner toroidal vortex (ITV) near a nozzle rim in small, laminar nonpremixed coflow flames, when an alternating current is applied to the nozzle. A systematic parametric study was conducted by varying the flow parameters of the fuel and coflowing-air velocities, and the nozzle diameter. The fuels tested were methane, ethylene, ethane, propane, n-butane, and i-butane, each representing different ion-generation characteristics and sooting tendencies. The results showed that the fluid dynamic effects on ITV formation were weak, causing only mild variation when altering flow velocities. However, increased fuel velocity resulted in increased polycyclic aromatic hydrocarbon (PAH) formation, which promoted ITV formation. When judging the ITV-formation tendency based on critical applied voltage and frequency, it was qualitatively well correlated with the PAH concentration and the relative location of PAHs to the nozzle rim. The sooting tendency of the fuels did not affect the results much. A change in the nozzle diameter highlighted the importance of the relative distance between the PAH zone and the nozzle rim, indicating the role of local electric-field intensity on ITV formation. Detailed onset conditions, characteristics of near-nozzle flow patterns, and PAH distributions are also discussed.
International Nuclear Information System (INIS)
Lee, V.D.
1987-01-01
The Fusion Engineering Design Center (FEDC) is part of a national design team that is developing the conceptual design of the Compact Ignition Tokamak (CIT). To achieve a compact device with the minimum major radius, a vertical preload system is being developed to react the vertical separating force normally carried by the inboard leg of the toroidal field (TF) coils. The preload system is in the form of a hydraulic press. Challenges in the design include the development of hydraulic and structural systems for very large force requirements, which could interface with the CIT machine, while allowing maximum access to the top, bottom, and radial periphery of the machine. Maximum access is necessary for maintenance, diagnostics, instrumentation, and control systems. Materials used in the design must function in the nuclear environment and in the presence of high magnetic fields. The structural system developed is an arrangement in which the CIT device is installed in the jaws of the press. Large built-up beams above and below the CIT span the machine and deliver the vertical force to the center cylinder formed by the inboard legs of the TF coils. During the conceptual design study, the vertical force requirement has ranged between 25,000 and 52,000 t. The access requirement on top and bottom limits the width of the spanning beams. Nonmagnetic steel materials are also required because of operation in the high magnetic fields. In the hydraulic system design for the press, several options are being explored. These range from small-diameter jacks operating at very high pressure [228 MPa (33 ksi)] to large-diameter jacks operating at pressures up to 69 MPa (10 ksi). Configurations with various locations for the hydraulic cylinders have also been explored. The nuclear environment and maintenance requirements are factors that affect cylinder location. This paper presents the configuration development of the hydraulic press used to vertically preload the CIT device
Low-n shear Alfven spectra in axisymmetric toroidal plasmas
Energy Technology Data Exchange (ETDEWEB)
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.
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
On the role of poloidal and toroidal fluctuating electric fields in tokamak transport
International Nuclear Information System (INIS)
Isichenko, M.B.; Wootton, A.J.
1995-01-01
The two different expressions for the radial particle flux Λ found in the literature, as given by equations (2) and (4), are identical if the parallel electric field is small. The first expression is derivable in a fluid approach, whereas the second follows from the analysis of individual particle orbits. These expressions, without change, are also valid for an arbitrary axisymmetric magnetic geometry. In a situation where the parallel electric field is significant, the more accurate expression for the particle flux is in terms of the standard E x B velocity
Numerical computation of the transport matrix in toroidal plasma with a stochastic magnetic field
Zhu, Siqiang; Chen, Dunqiang; Dai, Zongliang; Wang, Shaojie
2018-04-01
A new numerical method, based on integrating along the full orbit of guiding centers, to compute the transport matrix is realized. The method is successfully applied to compute the phase-space diffusion tensor of passing electrons in a tokamak with a stochastic magnetic field. The new method also computes the Lagrangian correlation function, which can be used to evaluate the Lagrangian correlation time and the turbulence correlation length. For the case of the stochastic magnetic field, we find that the order of magnitude of the parallel correlation length can be estimated by qR0, as expected previously.
Ambipolar electric fields and turbulence studies in the Wisconsin levitated toroidal octupole
International Nuclear Information System (INIS)
Armentrout, C.J.
1977-01-01
Detailed studies of hot ion plasmas (T/sub i/ > T/sub e/) in the poloidal field octupole show that the ambipolar electric field which is perpendicular to the flux surfaces is well explained by the observed properties of the microturbulence structures in the plasma. The turbulence structure has been measured by correlation techniques which are carefully described. In these experiments, signals were studied which are aperiodic in time and space, short lived compared to the decay times of the bulk plasma parameters, short ranged compared to the machine size, and are therefore classified as microturbulence structures. The resulting spatial and temporal correlation functions (CFs) are well fitted to a Gaussian function and the associated correlation lengths or times are the half width at half maximum of the CFs. The correlation length is measured to be the ion gyro radius for the hot hydrogen plasma and somewhat less for the helium plasma
Optimization of confinement in a toroidal plasma subject to strong radial electric fields
International Nuclear Information System (INIS)
Roth, J.R.
1977-01-01
A preliminary report on the identification and optimization of independent variables which affect the ion density and confinement time in a bumpy torus plasma is presented. The independent variables include the polarity, position, and number of the midplane electrode rings, the method of gas injection, and the polarity and strength of a weak vertical magnetic field. Some characteristic data taken under condition when most of the independent variables were optimized are presented. The highest value of the electron number density on the plasma axis is 3.2 x 10 to the 12th power/cc, the highest ion heating efficiency is 47 percent, and the longest particle containment time is 2.0 milliseconds
Shear stress peaks in a superconductor cable during the winding of a large toroidal field coil
International Nuclear Information System (INIS)
Zehlein, H.
1983-01-01
The paper presents a simplified elastica conductor model (SECM) built by a finite chain of intervals with constant bending moment and curvature. The problem does not allow to linearize the curvature. A bilinear moment-curvature relationship as derived from bending experiments was used to describe the elastoplastic behaviour of the cable under different tension forces acting on the ''free'' end near the supply spool. Due to the geometric and material nonlinearities mentioned no direct solution is possible. The paper describes the discrete model as well as the iterative shooting method which finds the equilibrium shape of the conductor. The distributions of bending moment and shear forces on the D-shaped contour as well as along the conductor are given. They show a pronounced influence of the tension force in the relevant range of 1 to 40 kN. An inconsistency due to compromising model simplifications is shown which occurs at the contour points where the curvature radius suddenly changes. Remarks on the elastic springback of the superconductor observed there conclude the paper
International Nuclear Information System (INIS)
1980-07-01
This report presents the conceptual design of an ETF compatible toroidal field coil, employing helium bath cooled NbTi alloy conductor. The ten TF-coil array generates a peak field of 11-1/2 tesla at 2.87 m radius, corresponding to a major axis field of 6.1 tesla. The 10 kA conductor is an uninsulated, unsoldered Rutherford cable, employing NbTiTa ally as developed in Phase I of this effort. The conductor is encased within a four element frame of stainless steel strips to provide hoop and bearing load support
International Nuclear Information System (INIS)
Ohmori, Junji; Koizumi, Norikiyo; Shimizu, Tatsuya; Okuno, Kiyoshi; Hasegawa, Mitsuru
2009-09-01
The winding pack (WP) of the Toroidal Field (TF) coil of ITER consists of 7 double-pancakes (DPs). In the DP, the conductor is embedded in a groove of a radial plate (RP), and cover plates (CP) are welded to the RP teeth to fix the conductors in the RP groove. The dimensions of the DP are 15 m in height and 9 m in width while the tolerances of the DP are very severe, such as a flatness of 2 mm and an in-plane deviation of a few millimeters. It is therefore required to reduce the deformation of the DP by CP welding. In order to estimate welding deformation, the authors apply an analytical method in which the CP welding deformation of the DP can be calculated using inherent strain evaluated from welding deformation measured using a RP mock-up. Calculated results indicate that out-of-plane distortion can be kept to within required tolerances, but in-plane deformation is larger than allowed when welding thickness is 2.5 mm. The in-plane deformation is mainly caused by the bending of the curved RP region. Therefore, reducing the welding thickness at the curved region emerges as the most promising solution of this issue. Calculated results assuming a welding thickness of 1 mm at the curved region show that the in-plane deformation conforms to required tolerances. Furthermore, since the maximum out-of-plane deformation is within tolerances but marginal, an alternative design in which the number of welding lines is half that of the reference design, is proposed not only to improve the out-of-plane distortion but also to simplify the manufacture of the DP. It is found that the alternative design is effective in reducing welding distortion. (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
Creep Effects in the Toroidal Field Coils of Fire and Other Burning Plasma Tokamaks
International Nuclear Information System (INIS)
Titus, Peter H.; Salvetti, Matteo
2003-01-01
All three burning plasma experiments discussed at Snowmass during the summer of 2002, use preloaded structures to resist some component of the operating loads. For the resistive pulsed reactors, it is the preloads which introduce the most noticeable creep responses because these loads are applied for much longer than the operating loads. If the preloads are maintained during shut-down and maintenance periods, then the structure experiences the preload stresses at room temperature. OFHC copper has significant creep behavior, predominantly at high stress and high temp, but copper experiences finite creep even at cryogenic temperatures. The Beryllium copper used in the FIRE inner leg has better creep properties than OFHC copper.The purpose of these analyses is to characterize the influence of creep on the magnets of the Fusion Ignition Research Reactor (FIRE) and compare it with the creep response of the other proposed burning plasma experiments. The concern is that the desirable features provided by coil preloads will be lost over the lives of the experiments. Structural finite element models of FIRE and IGNITOR are used with creep equations derived from NIST[6] data to explore the structural sensitivity of the machines to creep. For both FIRE and IGNITOR, copper coil material, creep has been found to have a minimal effect on magnet performance. IGNITOR's generally lower stresses (with respect to FIRE's BeCu TF stresses) and the use of active as well as passive preload systems helps reduce creep to acceptable levels. FIRE's structure is more sensitive to creep due to the free standing wedged TF coil, but the BeCu used in FIRE's inner TF legs has a much lower creep behavior than ETP or OFHC copper. This reduces creep to acceptable levels. For FIRE, however, there is some creep in the horizontal legs which relaxes some of the support of the inner leg. Recommendations are presented to support the OFHC copper horizontal legs more effectively. More work is needed to
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
International Nuclear Information System (INIS)
Nakajima, Noriyoshi; Okamoto, Masao.
1992-05-01
Effects of external momentum sources, i.e., fast ions produced by the neutral beam injection and an external inductive electric field, on the neoclassical ion parallel flow, current, and rotation are analytically investigated for a simple plasma in general toroidal systems. It is shown that the contribution of the external sources to the ion parallel flow becomes large as the collision frequency of thermal ions increases because of the momentum conservation of Coulomb collisions and sharply decreasing viscosity coefficients, with collision frequency. As a result, the beam-driven parallel flow of thermal ions becomes comparable to that of electrons in the Pfirsh-Schluter collisionality regime, whereas in the 1/μ or banana regime it is smaller than that of electrons by the order of √(m e /m i ) (m e and m i are electron and ion masses). This beam-driven ion parallel flow can not produce a large beam-driven current because of the cancellation with electron parallel flow, but produces a large toroidal rotation of ions. As both electrons and ions approach the Pfirsh-Schluter collisionality regime the contribution of thermodynamical forces becomes negligibly small and the large toroidal rotation of ions is predominated by the beam-driven component in the non-axisymmetric configuration with large helical ripples. (author)
Effects of 3D magnetic perturbations on toroidal plasmas
International Nuclear Information System (INIS)
Callen, J.D.
2011-01-01
stochasticity and increase plasma transport in the edge of H-mode plasmas. These various effects of 3D fields can be used to modify directly the plasma toroidal rotation (and possibly transport via multiple RMPs for controlling edge localized modes) and indirectly anomalous plasma transport. The present understanding and modelling of these various 3D magnetic field perturbation effects including for test blanket modules in ITER are summarized. Finally, implications of the present understanding and key open issues for developing a predictive capability of them for ITER are discussed. (topical review)
International Nuclear Information System (INIS)
Barbosa, Luis Filipe F.P.W.; Bosco, Edson del.
1994-01-01
This report presents the project and analysis of the circuit for production of the toroidal magnetic field in the Tokamak ETE (Spherical Tokamak Experiment). The ETE is a Tokamak with a small-aspect-ratio parameter to be used for studying the plasma physics for the research on thermonuclear fusion. This machine is being constructed at the Laboratorio Associado de Plasma (LAP) of the Instituto Nacional de Pesquisas Espaciais (INPE) in Sao Jose dos Campos, SP, Brazil. (author). 20 refs., 39 figs., 4 tabs
Modelling the erosion/deposition pattern of the Tore Supra Toroidal Pumped Limiter
International Nuclear Information System (INIS)
Panayotis, S.; Pégourié, B.; Borodin, D.; Kirschner, A.; Gunn, J.; Marandet, Y.; Mellet, N.
2015-01-01
This paper aims at understanding the main processes responsible for the erosion/deposition pattern observed on the surface of the Toroidal Pumped Limiter of Tore Supra, using the 3D local impurity transport code ERO. The influence of the plasma impurity content, CX-flux and surface temperature on the global carbon balance and erosion/deposition pattern is discussed. Main results are (1) that considering medium-range transport of C ions is mandatory for reproducing the main characteristics of the global C balance and erosion/deposition pattern, (2) that impurities and CX-atoms increase the erosion by a factor ⩽2 (without changing the net/gross erosion ratio), and (3) that chemical erosion is governed by the re-erosion of deposits, which depends strongly on the surface temperature
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)
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
DEFF Research Database (Denmark)
Mantica, P.; Tala, T.; Ferreira, J.S.
2010-01-01
Perturbative experiments have been carried out in the Joint European Torus [Fusion Sci. Technol. 53(4) (2008)] in order to identify the diffusive and convective components of toroidal momentum transport. The torque source was modulated either by modulating tangential neutral beam power...... or by modulating in antiphase tangential and normal beams to produce a torque perturbation in the absence of a power perturbation. The resulting periodic perturbation in the toroidal rotation velocity was modeled using time-dependent transport simulations in order to extract empirical profiles of momentum...
International Nuclear Information System (INIS)
Xu, Minfeng
1995-01-01
The electromagnetic analysis is mainly based on model built with 3-D electromagnetic software OPERA/TOSCA. In the process of evaluating the software package, some models are also built with 3-D boundary element electromagnetic software AMPERES. Fortran programs are also developed at B ampersand W to perform Monte-Carlo simulations of the field error analysis to assist tolerance determinations
Directory of Open Access Journals (Sweden)
L. Toledo Sesma
2016-01-01
Full Text Available We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW equation in the context of standard quantum cosmology.
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.)
Frassinetti, L.; Yagi, Y.; Koguchi, H.; Shimada, T.; Hirano, Y.; Sakakita, H.
2006-04-01
The pulsed poloidal current drive technique reduces the magnetic chaos that characterizes reversed-field pinch configurations and produces a regime with an improved confinement. In this paper, we describe that, in TPE-RX [Y. Yagi et al., Fusion Eng. Des. 45, 409 (1999)], the termination phase of this regime is due to the increase of the slinky structure that creates a stochastic region and produces the expulsion of energy in a localized toroidal position. Before the plasma reaches the improved confinement regime, the slinky distorts the chain of m =0 islands on the reversal surface. During this regime, the magnetic activity and the phase locking decrease, the distortion in the island chain disappears, and the confinement increases. At the termination of this regime the magnetic activity markedly increases, as well as the phase locking, recreating the distortion in the m =0 magnetic island chain. As a consequence, at the position of the distortion the plasma region inside the reversal surface is characterized by a rapid energy loss, and outside the reversal surface a toroidally localized energy expulsion is induced.
International Nuclear Information System (INIS)
Frassinetti, L.; Yagi, Y.; Koguchi, H.; Shimada, T.; Hirano, Y.; Sakakita, H.
2006-01-01
The pulsed poloidal current drive technique reduces the magnetic chaos that characterizes reversed-field pinch configurations and produces a regime with an improved confinement. In this paper, we describe that, in TPE-RX [Y. Yagi et al., Fusion Eng. Des. 45, 409 (1999)], the termination phase of this regime is due to the increase of the slinky structure that creates a stochastic region and produces the expulsion of energy in a localized toroidal position. Before the plasma reaches the improved confinement regime, the slinky distorts the chain of m=0 islands on the reversal surface. During this regime, the magnetic activity and the phase locking decrease, the distortion in the island chain disappears, and the confinement increases. At the termination of this regime the magnetic activity markedly increases, as well as the phase locking, recreating the distortion in the m=0 magnetic island chain. As a consequence, at the position of the distortion the plasma region inside the reversal surface is characterized by a rapid energy loss, and outside the reversal surface a toroidally localized energy expulsion is induced
Yadikin, D.; Brunsell, P. R.; Drake, J. R.
2006-01-01
An active feedback system is required for long pulse operation of the reversed field pinch (RFP) device to suppress resistive wall modes (RWMs). A general feature of a feedback system using a discrete active coil array is a coupling effect which arises when a set of side band modes determined by the number of active coils is produced. Recent results obtained on the EXTRAP T2R RFP demonstrated the suppression of independent m = 1 RWMs using an active feedback system with a two-dimensional array of discrete active coils in the poloidal and toroidal directions. One of the feedback algorithms used is the intelligent shell feedback scheme. Active feedback systems having different number of active coils in the poloidal (Mc) and toroidal (Nc) directions (Mc × Nc = 2 × 32 and Mc × Nc = 4 × 16) are studied. Different side band effects are seen for these configurations. A significant prolongation of the plasma discharge is achieved for the intelligent shell feedback scheme using the 2 × 32 active coil configuration. This is attributed to the side band sets including only one of the dominant unstable RWMs and avoiding coupling to resonant modes. Analog proportional-integral-derivative controllers are used in the feedback system. Regimes with different values of the proportional gain are studied. The requirement of the proportional-integral control for low proportional gain and proportional-derivative control for high proportional gain is seen in the experiments.
Dynamical conservation of invariants by toroidal trajectories of guiding centres
International Nuclear Information System (INIS)
Misguich, J.H.
1992-03-01
The classical problem of calculating toroidal trajectories is treated here by comparing the results of two different methods in a given magnetic configuration, a standard divergence-free magnetic field model. The present work consists of adapting the analytical criteria of MERCIER et al. for classical toroidal trajectories, and to examine numerically the dynamical conservation of the toroidal invariant. The first method is based on the evolution equations for the guiding centres. These equations are then solved numerically (code TRATORIA) and the trajectories are drawn for different initial conditions. We use a modified standard model for the magnetic field, which insures a manifestly divergence-free field. Moreover we take into account the contribution of the poloidal field to the total strength of the magnetic field. These corrections contribute to the analytical expression of the conserved toroidal momentum. The latter is verified to be conserved by the present numerical simulation with a precision generally of the order of 10 -14 . The second method is based on the analytical treatment of the invariants to yield a semi-analytical (semi graphical) determination of the intersection point of a given trajectory with the equatorial plane. Both methods allows one to recover well-known toroidal trajectories with passing and trapped particles (bananas). The present analysis brings a clear description of some other, less well-known types of trajectories, namely the stagnation orbits, the smallest D-shape banana, some small circulating de-flated bananas, some huge classical bananas (potatoes), and the largest puffed bananas which exhibit only local mirroring, along with several kind of escaping or open trajectories which are of importance for fast ion losses and target damages in the machines
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 ...
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....
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
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
Energy Technology Data Exchange (ETDEWEB)
Lakhin, V. P.; Sorokina, E. A., E-mail: sorokina.ekaterina@gmail.com, E-mail: vilkiae@gmail.com; Ilgisonis, V. I. [National Research Centre Kurchatov Institute (Russian Federation); Konovaltseva, L. V. [Peoples’ Friendship University of Russia (Russian Federation)
2015-12-15
A set of reduced linear equations for the description of low-frequency perturbations in toroidally rotating plasma in axisymmetric tokamak is derived in the framework of ideal magnetohydrodynamics. The model suitable for the study of global geodesic acoustic modes (GGAMs) is designed. An example of the use of the developed model for derivation of the integral conditions for GGAM existence and of the corresponding dispersion relation is presented. The paper is dedicated to the memory of academician V.D. Shafranov.
Directory of Open Access Journals (Sweden)
Yoder Alberto Suaza
2014-01-01
Full Text Available Se calcula la estructura de energía de un ión D - , es decir dos electrones ligados a una impureza donadora fija, encarcelada en un anillo cuántico toroidal cuando el sistema completo está simultáneamente bajo la presencia de un campo de presión hidrostática y de un campo magnético. Con el propósito de estudiar las propiedades del ión D - , nosotros asumimos que los anillos cuánticos son muy estrechos, lo cual nos permitirá usar la bien conocida aproximación adiabática para desacoplar el movimiento rápido en direcciones radial y axial del movimiento lento de rotación. Se estudian los cambios en el ordenamiento de los niveles y el cruce entre las curvas como una función de la línea central del anillo, posición de la donadora, y del campo magnético para diferentes valores de presión hidrostática. Finalmente, nosotros comparamos los resultados con aquellos previamente reportados para casos límites. A partir de estas comparaciones es posible establecer un excelente acuerdo entre los diferentes resultados, lo cual demuestra la calidad del modelo implementado en este trabajo.
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.
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 ...
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.
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 of DC toroidal current by a travelling wave
International Nuclear Information System (INIS)
Matsuura, K.; Fukuda, M.; Hirano, K.; Mohri, A.; Fukao, M.; Midzuno, Y.
1974-01-01
An rf field travelling along the torus is observed to induce a dc toroidal current in a magnetized plasma. The travelling field is applied to the plasma by employing a delay-line wound around the toroidal glass discharge tube. The phase velocity of the field is approximately equal to the electron thermal velocity. The direction of the current is opposite to that of the wave, indicating that the electrons are trapped in the magnetic mirrors composed of the travelling wave. The density of the trapped electrons reaches 10 percent of the background plasma density at an optimum condition. On the basis of the electron trapping model, the required rf power for current sustaining in a Tokamak fusion reactor is estimated and found to be reasonably small in comparison with the output power of the reactor
A 'rational' explanation of resonant surfaces in toroidal plasmas
International Nuclear Information System (INIS)
Cross, R.C.
1983-05-01
Resonant surfaces are of fundamental importance in toroidal plasmas, particularly in relation to stability theory. A simple explanation as to why these surfaces are 'resonant' is given in terms of the propagation of localized torsional Alfven and ion acoustic wave packets. These packets are guided along helical field lines in toroidal plasmas, leading to the formation of unstable standing waves on those field lines which close on themselves after one or more toroidal revolutions
DIVIMP Modeling of the Toroidally-Symmetrical Injection of 13CH4 into the Upper SOL of DIII-D
Energy Technology Data Exchange (ETDEWEB)
McLean, A G; Elder, J D; Stangeby, P C; Allen, S L; Brooks, N H; Fenstermacher, M E; Groth, M; Lisgo, S; Nagy, A; Wampler, W R; Watkins, J G; West, W P; Whyte, D G
2004-12-03
As part of a study of carbon-tritium co-deposition, we carried out an experiment on DIII-D involving a toroidally symmetric injection of {sup 13}CH{sub 4} at the top of a LSN discharge. A Monte Carlo code, DIVIMP-HC, which includes molecular breakup of hydrocarbons, was used to model the region near the puff. The interpretive analysis indicates a parallel flow in the SOL of M{sub l} {approx} 0.4 directed toward the inner divertor. The CH{sub 4} is ionized in the periphery of the SOL and so the particle confinement time, {tau}{sub c}, is not high, only {approx}5 ms, and about 4X lower than if the CH{sub 4} were ionized at the separatrix. For such a wall injection location, however, most of the CH{sub 4} gets ionized to C{sup +}, C{sup ++}, etc., and is efficiently transported along the SOL to the inner divertor, trapping hydrogen by co-deposition there.
DIVIMP modeling of the toroidally-symmetrical injection of 13 CH4 into the upper SOL of DIII-D.
Energy Technology Data Exchange (ETDEWEB)
Brooks, N. (General Atomics); Nagy A. (General Atomics); McLean, A. G. (University of Toronto Institute for Aerospace Studies); Groth, M. (Lawrence Livermore National Laboratory); Elder, J. D. (University of Toronto Institute for Aerospace Studies); Fenstermacher, M. E. (Lawrence Livermore National Laboratory); Whyte, D. G. (University of Wisconsin - Madison); Lisgo, S. (University of Toronto Institute for Aerospace Studies); Allen, S. L. (Lawrence Livermore National Laboratory); West, W.P. (General Atomics); Stangeby, P C (University of Toronto Institute for Aerospace Studies); Watkins, Jonathan G.; Wampler, William R.
2004-05-01
As part of a study of carbon-tritium co-deposition, we carried out an experiment on DIII-D involving a toroidally symmetric injection of {sup 13}CH{sub 4} at the top of a LSN discharge. A Monte Carlo code, DIVIMP-HC, which includes molecular breakup of hydrocarbons, was used to model the region near the puff. The interpretive analysis indicates a parallel flow in the SOL of M {parallel} {approx} 0.4 directed toward the inner divertor. The CH{sub 4} is ionized in the periphery of the SOL and so the particle confinement time, T{sub C}, is not high, only {approx} 5 ms, and about 4X lower than if the CH{sub 4} were ionized at the separatrix. For such a wall injection location, however, approximately 60-75% of the CH{sub 4} gets ionized to C{sup +}, C{sup 2+}, etc., and is efficiently transported along the SOL to the inner divertor, trapping hydrogen by co-deposition there.
Hamiltonian guiding center drift orbit calculation for toroidal plasmas of arbitrary cross section
Energy Technology Data Exchange (ETDEWEB)
White, R.B.; Chance, M.S.
1984-02-01
A Hamiltonian guiding center drift orbit formalism is developed which permits the efficient calculation of particle trajectories in toroidal devices of arbitrary cross section with arbitrary plasma ..beta... The magnetic field is assumed to be a small perturbation from a zero order toroidal equilibrium field possessing either axial or helical symmetry. The equilibrium field can be modelled analytically or obtained numerically from equilibrium codes. A numerical code based on the formalism is used to study particle orbits in circular and bean-shaped tokamak configurations.
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)
Magnetohydrodynamic equilibrium of axisymmetric systems with toroidal rotation
International Nuclear Information System (INIS)
Mansur, N.L.P.
1986-01-01
A model for studying magnetohydrodynamic equilibrium of axisymetrically confined plasma with toroidal rotation, extended to the Grad. Shafranov equation is presented. The expression used for the scalar pressure is modifiec, and the influence of toroidal magnetic field is included, The equation for general motion of axisymetrically confined plasma, particularizing for rotation movements is described. Two cases are compared: one supposes the entropy as a function of poloidal magnetic flux and other supposes the temperature as a function of flux. The equations for these two cases obtaining a simplified expression by others approximations are established. The proposed model is compared with Shibata model, which uses density as function of flux, and with the ideal spheromak model. A set of cases taking in account experimental data is studied. (M.C.K.) [pt
Modeling of the three-dimensional motion of toroidal magnetic clouds in the inner heliosphere
Czech Academy of Sciences Publication Activity Database
Romashets, E.; Vandas, Marek; Poedts, S.
2007-01-01
Roč. 466, č. 1 (2007), s. 357-365 ISSN 0004-6361 R&D Projects: GA AV ČR 1QS300120506; GA ČR GA205/06/0875 Institutional research plan: CEZ:AV0Z10030501 Keywords : magnetic cloud s * interplanetary magnetic field Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.259, year: 2007
Development of 3D ferromagnetic model of tokamak core with strong toroidal asymmetry
DEFF Research Database (Denmark)
Markovič, Tomáš; Gryaznevich, Mikhail; Ďuran, Ivan
2015-01-01
Fully 3D model of strongly asymmetric tokamak core, based on boundary integral method approach (i.e. characterization of ferromagnet by its surface) is presented. The model is benchmarked on measurements on tokamak GOLEM, as well as compared to 2D axisymmetric core equivalent for this tokamak, pr...
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)
Magnetic field 3D-reconstruction techniques using images of an ion beam in a toroidal plasma
Ling, C.; Connor, K. A.; Demers, D. R.; Radke, R. J.; Schoch, P. M.
2004-11-01
A technique to map the magnetic field of a plasma via spectral imaging of a heavy ion beam is being developed on the Madison Symmetric Torus (MST). This technique will provide both spatial and temporal magnetic field information. A code has been developed to analyze spectral images of the beam. To assess the technique, the code utilizes a trajectory produced with a known magnetic field and simulates two 2D-images of this trajectory. These 2D-images are used to reconstruct a 3D-trajectory and compute the magnetic field in the vicinity of the beam. The magnetic field components that are perpendicular to the beam velocity field can be resolved, but there is insufficient information to resolve the component along the beam velocity field. Hence, additional constraints such as shifted, circular, closed magnetic flux surfaces are used. We discuss details of the simulation including various image processing algorithms, accuracy of the reconstructed 3D-trajectory, and agreement between the prescribed and computed magnetic fields.
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)
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.
Development of 3D ferromagnetic model of tokamak core withstrong toroidal asymmetry
Czech Academy of Sciences Publication Activity Database
Markovič, Tomáš; Gryaznevich, M.; Ďuran, Ivan; Svoboda, V.; Pánek, Radomír
96-97, October (2015), s. 302-305 ISSN 0920-3796. [Symposium on Fusion Technology 2014(SOFT-28)/28./. San Sebastián, 29.09.2014-03.10.2014] R&D Projects: GA ČR GAP205/11/2341; GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * ferromagnetic core * model of ferromagnet * integral method * tokamak GOLEM Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.301, year: 2015 http://www.sciencedirect.com/science/article/pii/S0920379615002100
Collisionless kinetic-fluid model of zonal flows in toroidal plasmas
International Nuclear Information System (INIS)
Sugama, H.; Watanabe, T.-H.; Horton, W.
2006-12-01
A novel kinetic-fluid model is presented, which describes collisionless time evolution of zonal flows in tokamaks. In the new zonal-flow closure relations, the parallel heat fluxes are written by the sum of short- and long-time-evolution parts. The former part is given in the dissipative form of the parallel heat diffusion and relates to collisionless damping processes. The latter is derived from the long-time-averaged gyrocenter distribution and plays a major role in describing low-frequency or stationary zonal flows, for which the parallel heat fluxes are expressed in terms of the parallel flow as well as the nonlinear-source and initial-condition terms. It is shown analytically and numerically that, when applied to the zonal flow driven by either ion or electron temperature gradient turbulence, the kinetic-fluid equations including the new closure relations can reproduce the same long-time zonal-flow responses to the initial condition and to the turbulence source as those obtained from the gyrokinetic model. (author)
Xiong, Yuan
2016-06-24
Dynamical and electrical responses of a small coflow diffusion flame were investigated by applying a high-voltage alternating current (AC), to a fuel jet nozzle. High-speed imaging and electrical diagnostics were adopted to capture flame dynamics and electrical signals, such as voltage (V ), frequency (f ) and current (I ). In the V -f domain of 0-5kV and 0-5kHz, AC-driven instabilities, resulting in various flame modes such as an oscillation, pinch-off and spinning of flames were identified. Characteristic frequency of each mode was determined and a visualization of near-nozzle flow structures suggested a close causality of initial counter-rotating vortices (inner and outer toroidal vortices - ITV and OTV), to the other observed flame. An axisymmetric ITV shedding was identified within oscillating and pinch-off modes, while asymmetric ITV shedding was identified with the spinning mode. Integrated electric power over several AC periods correlated well with variation in the flame surface area for these instabilities, demonstrating that measured electric power is a potential indicator of combustion instabilities in electric-field-assisted combustion.
Comparative study of a constant-alpha force-free field and its approximations in an ideal toroid
Czech Academy of Sciences Publication Activity Database
Vandas, Marek; Romashets, E.
2015-01-01
Roč. 580, August (2015), A123/1-A123/7 ISSN 0004-6361 R&D Projects: GA ČR(CZ) GA14-19376S Institutional support: RVO:67985815 Keywords : solar wind * magnetic fields * magnetohydrodynamics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014
Energy Technology Data Exchange (ETDEWEB)
Barnes, D.C.; Fernandez, J.C.; Rej, D.J. (comps.)
1990-05-01
The US-Japan Workshop on Field-Reversed Configurations with Steady-State High-Temperature Fusion Plasma and the 11th US-Japan Workshop on Compact Toroids were held at Los Alamos National Laboratory, Los Alamos, New Mexico on November 7--9, 1989. These proceedings contain the papers presented at the workshops as submitted by the authors. These papers have been indexed separately.
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
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.
Stabilization of ballooning modes with sheared toroidal rotation
International Nuclear Information System (INIS)
Miller, R.L.; Waelbroeck, F.L.; Hassam, A.B.; Waltz, R.E.
1995-01-01
Stabilization of magnetohydrodynamic ballooning modes by sheared toroidal rotation is demonstrated using a shifted circle equilibrium model. A generalized ballooning mode representation is used to eliminate the fast Alfven wave, and an initial value code solves the resulting equations. The s-α diagram (magnetic shear versus pressure gradient) of ballooning mode theory is extended to include rotational shear. In the ballooning representation, the modes shift periodically along the field line to the next point of unfavorable curvature. The shift frequency (dΩ/dq, where Ω is the angular toroidal velocity and q is the safety factor) is proportional to the rotation shear and inversely proportional to the magnetic shear. Stability improves with increasing shift frequency and direct stable access to the second stability regime occurs when this frequency is approximately one-quarter to one-half the Alfven frequency, ω A =V A /qR. copyright 1995 American Institute of Physics
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.)
Low-frequency fluctuations in a pure toroidal magnetized plasma
Indian Academy of Sciences (India)
Abstract. A magnetized, low-β plasma in pure toroidal configuration is formed and ex- tensively 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.
Dynamics of accelerated compact toroidal plasmas
International Nuclear Information System (INIS)
McLean, H.S.; Eddleman, J.L.; Hammer, J.H.; Hartman, C.W.; Molvik, A.W.
1990-01-01
Previous work on the RACE experiment has demonstrated acceleration and focusing of spheromak-type compact toroids of low mass (10 μg), low density (10 13 cm -3 ), and low magnetic field (2 KG). Computer modeling and measurements give reasonably good accounting of ring mass, momentum, and energy. Present work has been toward increasing the ring magnetic field and utilizing inductive storage by compressing similar plasma rings prior to acceleration. The precompression, followed by acceleration has been performed. Ring density and magnetic field have increased (n e ∼ 10 15 cm -3 , B ∼ 4 KG) in the precompression cone, and magnetic field increases (B ∼ 8--12 KG) after compression and during acceleration, however, trajectory measurements have shown an increase in drag or possibly ring mass above that accounted for by the density measurements in the precompression cone. For the low mass/density/field rings, drag forces did not need to be invoked for agreement between modeling and experiment and mass was consistent with electron density measurements. Drag and/or mass change is now apparently important in this higher mass/density/field regime
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
International Nuclear Information System (INIS)
Campbell, V.W.; Dooley, J.B.; Hubrig, J.G.; Janke, C.J.; McManamy, T.J.; Welch, D.E.
1990-01-01
Design criteria for the Compact Ignition Tokamak, Toroidal-Field (TF) Coil, Turn-to-Turn Insulation System require an insulation sheet and bonding system that will survive cryogenic cycling in a radiation environment and maintain structural integrity during exposure to the significant compressive and shear loads associated with each operating cycle. For thermosetting resin systems, a complex interactive dependency exists between optimum peak value, in-service property performance capabilities of candidate generic materials; key handling and processing parameters required to achieve their optimum in-service property performance as an insulation system; and suitability of their handling and processing parameters as a function of design configuration and assembly methodology. This dependency is assessed in a weighted study matrix in which two principal programmatic approaches for the development of the TF Coil Subassembly Insulation System have been identified. From this matrix study, two viable approaches to the fabrication of the insulation sheet were identified: use of a press-formed sheet bonded in place with epoxy for mechanical bonding and tolerance take-up and formation of the insulation sheet by placement of dry cloth and subsequent vacuum pressure impregnation. Laboratory testing was conducted to screen a number of combinations of resins and hardeners on a generic basis. These combinations were chosen for their performance in similar applications. Specimens were tested to screen viscosity, thermal-shock tolerance, and cryogenic tolerance. Cryogenic shock and cryogenic temperature proved to be extremely lethal to many combinations of resin, hardener, and cure. Two combinations survived: a heavily flexibilized bisphenol A resin with a flexibilized amine hardener and a bisphenol A resin with cycloaliphatic amine hardener. 7 refs., 12 figs., 6 tabs
Wiegelmann, Thomas; Petrie, Gordon J. D.; Riley, Pete
2017-09-01
Coronal magnetic field models use photospheric field measurements as boundary condition to model the solar corona. We review in this paper the most common model assumptions, starting from MHD-models, magnetohydrostatics, force-free and finally potential field models. Each model in this list is somewhat less complex than the previous one and makes more restrictive assumptions by neglecting physical effects. The magnetohydrostatic approach neglects time-dependent phenomena and plasma flows, the force-free approach neglects additionally the gradient of the plasma pressure and the gravity force. This leads to the assumption of a vanishing Lorentz force and electric currents are parallel (or anti-parallel) to the magnetic field lines. Finally, the potential field approach neglects also these currents. We outline the main assumptions, benefits and limitations of these models both from a theoretical (how realistic are the models?) and a practical viewpoint (which computer resources to we need?). Finally we address the important problem of noisy and inconsistent photospheric boundary conditions and the possibility of using chromospheric and coronal observations to improve the models.
Toroidal Ampere-Faraday Equations Solved Consistently with the CQL3D Fokker-Planck Time-Evolution
Harvey, R. W.; Petrov, Yu. V.
2013-10-01
A self-consistent, time-dependent toroidal electric field calculation is a key feature of a complete 3D Fokker-Planck kinetic distribution radial transport code for f(v,theta,rho,t). In the present CQL3D finite-difference model, the electric field E(rho,t) is either prescribed, or iteratively adjusted to obtain prescribed toroidal or parallel currents. We discuss first results of an implementation of the Ampere-Faraday equation for the self-consistent toroidal electric field, as applied to the runaway electron production in tokamaks due to rapid reduction of the plasma temperature as occurs in a plasma disruption. Our previous results assuming a constant current density (Lenz' Law) model showed that prompt ``hot-tail runaways'' dominated ``knock-on'' and Dreicer ``drizzle'' runaways; we will examine modifications due to the more complete Ampere-Faraday solution. Work supported by US DOE under DE-FG02-ER54744.
2006-01-01
A 3-D event display of a cosmic muon event, showing the path of a muon travelling through three layers of the barrel muon spectrometer. Three of the eight coils of the barrel toroid magnet can be seen in the top half of the drawing.
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.
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...
Shilon, I.; Silva, H.; ten Kate, H.H.J.
2013-01-01
The International AXion Observatory (IAXO) will incorporate a new generation detector for axions, a hypothetical particle, which was postulated to solve one of the puzzles arising in the standard model of particle physics, namely the strong CP problem. The new IAXO experiment is aiming at achieving a sensitivity to the coupling between axions and photons of one order of magnitude beyond the limits of the current state-of-the-art detector, represented by 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 into x-ray photons. Utilizing the designs of the ATLAS barrel and end-cap toroids, a large superconducting toroidal magnet is currently being designed at CERN to provide the required magnetic field. The new toroid will be built up from eight, one meter wide and 20 m long, racetrack coils. The toroid is sized about 4 m in diameter and 22 m in length. It is designed to realize a peak magnetic field of 5.4 T with a ...
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)
Toroidal Dipole Moment of a Massless Neutrino
International Nuclear Information System (INIS)
Cabral-Rosetti, L. G.; Mondragon, M.; Perez, E. Reyes
2009-01-01
We obtain the toroidal dipole moment of a massless neutrino τ v l M using the results for the anapole moment of a massless Dirac neutrino a v l D , which was obtained in the context of the Standard Model of the electroweak interactions (SM)SU(2) L x U(1) Y .
International Nuclear Information System (INIS)
Siemon, R.E.
1981-03-01
This document contains papers contributed by the participants of the Third Symposium on Physics and Technology of Compact Toroids in the Magnetic Fusion Energy Program. Subjects include reactor aspects of compact toroids, energetic particle rings, spheromak configurations (a mixture of toroidal and poloidal fields), and field-reversed configurations
Equilibrium modeling of the TFCX poloidal field coil system
International Nuclear Information System (INIS)
Strickler, D.J.; Miller, J.B.; Rothe, K.E.; Peng, Y.K.M.
1984-04-01
The Toroidal Fusion Core Experiment (TFCX) isproposed to be an ignition device with a low safety factor (q approx. = 2.0), rf or rf-assisted startup, long inductive burn pulse (approx. 300 s), and an elongated plasma cross section (kappa = 1.6) with moderate triangularity (delta = 0.3). System trade studies have been carried out to assist in choosing an appropriate candidate for TFCX conceptual design. This report describes an important element in these system studies - the magnetohydrodynamic (MHD) equilibrium modeling of the TFCX poloidal field (PF) coil system and its impact on the choice of machine size. Reference design points for the all-super-conducting toroidal field (TF) coil (TFCX-S) and hybrid (TFCX-H) options are presented that satisfy given PF system criteria, including volt-second requirements during burn, mechanical configuration constraints, maximum field constraints at the superconducting PF coils, and plasma shape parameters. Poloidal coil current waveforms for the TFCX-S and TFCX-H reference designs consistent with the equilibrium requirements of the plasma startup, heating, and burn phases of a typical discharge scenario are calculated. Finally, a possible option for quasi-steady-state operation is discussed
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...
Quantum electron transport in toroidal carbon nanotubes
Jack, Mark; Encinosa, Mario
2008-03-01
Electron transport under bias is treated in tight-binding approximation using a non-equilibrium Green's function approach. Density-of-states D(E), transmissivity T(E), and current ISD are calculated through a (3,3) armchair nanotorus with laterally attached metallic leads and a magnetic field penetrating the toroidal plane. Plateaus in T(E) through the torus are observed as a function of both the relative angle between leads and magnetic flux. Initial computational studies performed with 1800 atoms and attached leads show substantial computational slowdown when increasing the system size by a factor of two. Results are generated by inverting the device Hamiltonian with a standard recursion method extended to account for unit cell toroidal closure. Significant computational speed-up is expected for a parallelized code on a multiprocessor computer cluster. The dependence of electronic features on torus size and torus curvature is tested for three tori with 900, 1800 and 3600 carbon atoms, respectively. References: 1. M. Jack and M. Encinosa, Quantum electron transport in toroidal carbon nanotubes with metallic leads. ArXiv: quant-ph/0709.0760. 2. M. Encinosa and M. Jack, Dipole and solenoidal magnetic moments of electronic surface currents on toroidal nanostructures. J. Comp.-Aided Mat. Design (Springer), 14 (1) (2007) 65 -- 71.
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)
Fixed boundary toroidal plasma equilibria with toroidal flows
Energy Technology Data Exchange (ETDEWEB)
Hu, Yanqiang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031 (China); Hu, Yemin; Xiang, Nong [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031 (China)
2016-04-15
The fixed boundary toroidal plasma equilibria with toroidal flows are investigated by solving the modified Grad-Shafranov equation numerically in the cylindrical coordinate system. For normal equilibrium configurations with geometry and profiles similar to usual tokamaks with no flow, it is found that the effect of flow is to lead to an outward shift of the magnetic flux surfaces, together with the profiles of pressure, and mass and current densities. The shifts could become significant when the toroidal flow Mach number exceeds 0.5. For non-conventional current profiles, even for the usual tokamak geometry, novel current reversal equilibrium configurations may result, sometimes with changed topology in the poloidal flux function. This change in the topology of plasma equilibrium can be attributed to the large toroidal flow. The computed results may correspond to situations of intense tangential injection during the low toroidal current phase in expected experimental situations.
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
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.)
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
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...
Auluck, S. K. H.
2017-11-01
This paper continues earlier discussion [S. K. H. Auluck, Phys. Plasmas 21, 102515 (2014)] concerning the formulation of conservation laws of mass, momentum, and energy in a local curvilinear coordinate system in the dense plasma focus. This formulation makes use of the revised Gratton-Vargas snowplow model [S. K. H. Auluck, Phys. Plasmas 20, 112501 (2013)], which provides an analytically defined imaginary surface in three dimensions which resembles the experimentally determined shape of the plasma. Unit vectors along the local tangent to this surface, along the azimuth, and along the local normal define a right-handed orthogonal local curvilinear coordinate system. The simplifying assumption that physical quantities have significant variation only along the normal enables writing laws of conservation of mass, momentum, and energy in the form of effectively one-dimensional hyperbolic conservation law equations using expressions for various differential operators derived for this coordinate system. This formulation demonstrates the highly non-trivial result that the axial magnetic field and toroidally streaming fast ions, experimentally observed by multiple prestigious laboratories, are natural consequences of conservation of mass, momentum, and energy in the curved geometry of the dense plasma focus current sheath. The present paper continues the discussion in the context of a 3-region shock structure similar to the one experimentally observed: an unperturbed region followed by a hydrodynamic shock containing some current followed by a magnetic piston. Rankine-Hugoniot conditions are derived, and expressions are obtained for the specific volumes and pressures using the mass-flux between the hydrodynamic shock and the magnetic piston and current fraction in the hydrodynamic shock as unknown parameters. For the special case of a magnetic piston that remains continuously in contact with the fluid being pushed, the theory gives closed form algebraic results for the
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.)
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
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
Energy Technology Data Exchange (ETDEWEB)
Luo, Xiangyi; Amine, Rachid; Lau, Kah Chun; Lu, Jun; Zhan, Chun; Curtiss, Larry A.; Hallaj, Said Al; Chaplin, Brian P.; Amine, Khalil
2017-12-01
The discharge and charge mechanisms of rechargeable Li-O-2 batteries have been the subject of extensive investigation recently. However, they are not fully understood yet. Here we report a systematic study of the morphological transition of Li2O2 from a single crystalline structure to a toroid like particle during the discharge-charge cycle, with the help of a theoretical model to explain the evolution of the Li2O2 at different stages of this process. The model suggests that the transition starts in the first monolayer of Li2O2, and is subsequently followed by a transition from particle growth to film growth if the applied current exceeds the exchange current for the oxygen reduction reaction in a Li-O-2 cell. Furthermore, a sustainable mass transport of the diffusive active species (e.g., O-2 and Li+) and evolution of the underlying interfaces are critical to dictate desirable oxygen reduction (discharge) and evolution (charge) reactions in the porous carbon electrode of a Li-O-2 cell.
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...
Kinetic Damping of Toroidal Alfven Eigenmodes
International Nuclear Information System (INIS)
Fu, G.Y.; Berk, H.L.; Pletzer, A.
2005-01-01
The damping of Toroidal Alfven Eigenmodes in JET plasmas is investigated by using a reduced kinetic model. Typically no significant damping is found to occur near the center of the plasma due to mode conversion to kinetic Alfven waves. In contrast, continuum damping from resonance near the plasma edge may be significant, and when it is, it gives rise to damping rates that are compatible with the experimental observations
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.
Studies of plasma self-organization in toroidal pinches
International Nuclear Information System (INIS)
Tamano, T.; Bard, W.D.; LaHaye, R.J.; Schaffer, M.J.; Taylor, P.L.
1987-01-01
Plasma self-organizations of toroidal pinch plasmas were observed in the OHTE device. The reversed field pinch discharges were sustained for about 15 ms longer than the shell time constant of 1.5 ms although linear MHD theories predict that MHD instabilities grow on the resistive shell time scale. Detailed studies of MHD activities led to the discovery of a toroidally localized kink mode. The slinky mode is the result of the phase locking of several internal kink modes due to non-linear coupling, and plays an important role in achieving the Taylor relaxed state. This is described in the first part of this lecture. Such phase lockings were observed not only for poloidal mode number m = -1 modes, but also for m = 0 and m = 1 modes. This provides some insight into how a tangled discharge can be formed. Tangled discharge models have been discussed by Rusbridge and others. However, the models do not provide a clean picture. The introduction of localized plasma deformation due to phase locking gives a simplified view of a tangled discharge. This is discussed in the second part of this lecture. The third part of this lecture describes another interesting plasma self-organization observed in the ultra low q regime. The plasma tend to maintain a constant current and shows a ''staircase''-like current behavior. 9 refs., 10 figs
Energy Technology Data Exchange (ETDEWEB)
McLean, A.G. [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ont., M3H 5T6 (Canada)]. E-mail: adam.mclean@utoronto.ca; Elder, J.D. [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ont., M3H 5T6 (Canada); Stangeby, P.C. [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ont., M3H 5T6 (Canada); Allen, S.L. [University of California, San Diego, La Jolla, CA 92093-0417 (United States); Boedo, J.A. [University of Wisconsin, Madison, WI 53706 (United States); Brooks, N.H. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Fenstermacher, M.E. [University of California, San Diego, La Jolla, CA 92093-0417 (United States); Groth, M. [University of California, San Diego, La Jolla, CA 92093-0417 (United States); Lisgo, S. [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ont., M3H 5T6 (Canada); Nagy, A. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Rudakov, D.L. [University of Wisconsin, Madison, WI 53706 (United States); Wampler, W.R. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Watkins, J.G. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); West, W.P. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Whyte, D.G. [Sandia National Laboratory, P.O. Box 5800, Albuquerque, NM 87185 (United States)
2005-03-01
As part of a study of carbon-tritium co-deposition, we carried out an experiment on DIII-D involving a toroidally symmetric injection of {sup 13}CH{sub 4} at the top of a LSN discharge. A Monte Carlo code, DIVIMP-HC, which includes molecular breakup of hydrocarbons, was used to model the region near the puff. The interpretive analysis indicates a parallel flow in the SOL of M {sub parallel} {approx} 0.4 directed toward the inner divertor. The CH{sub 4} is ionized in the periphery of the SOL and so the particle confinement time, {tau} {sub c}, is not high, only {approx}5 ms, and about 4X lower than if the CH{sub 4} were ionized at the separatrix. For such a wall injection location, however, approximately 60-75% of the CH{sub 4} gets ionized to C{sup +}, C{sup 2+}, etc., and is efficiently transported along the SOL to the inner divertor, trapping hydrogen by co-deposition there.
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
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
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1996-08-01
Transport processes and resultant entropy production in magnetically confined plasmas are studied in detail for toroidally rotating systems with electrostatic turbulence. A new gyrokinetic equation is derived for rotating plasmas with large flow velocities on the order of the ion thermal speed. Neoclassical and anomalous transport of particles, energy, and toroidal momentum are systematically formulated from the ensemble-averaged kinetic equation with the gyrokinetic equation. As a conjugate pair of the thermodynamic force and the transport flux, the shear of the toroidal flow, which is caused by the radial electric field shear, and the toroidal viscosity enter both the neoclassical and anomalous entropy production. The interaction between the fluctuations and the sheared toroidal flow is self-consistently described by the gyrokinetic equation containing the flow shear as the thermodynamic force and by the toroidal momentum balance equation including the anomalous viscosity. Effects of the toroidal flow shear on the toroidal ion temperature gradient driven modes are investigated. Linear and quasilinear analyses of the modes show that the toroidal flow shear decreases the growth rates and reduces the anomalous toroidal viscosity. (author)
International Nuclear Information System (INIS)
Leite Lopes, J.
1998-04-01
In this work, we discuss the physical ideas which represents the basis for the unified gauge field model. Despite of the difficulties that we presently have for embodying in a natural manner muons and hadrons in that model, we have the feeling that we are on the way which seems to lead to the construction of a theory in which the Maxwell electromagnetic field and the Fermi weak interaction field are manifestations of a unique subjacent physical entity - the unified gauge fields. (author)
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
New Superconducting Toroidal Magnet System for IAXO, the International AXion Observatory
Shilon, I; Silva, H; Wagner, U; Kate, H H J ten
2013-01-01
Axions are hypothetical particles that 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. The new International AXion Observatory (IAXO) will incorporate the most promising solar axions detector to date, which is designed to enhance the sensitivity to the axion-photon coupling by one order of magnitude beyond the limits of the current state-of-the-art 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 into X-ray photons. Inspired by the successful realization of the ATLAS barrel and end-cap toroids, a very large superconducting toroid is currently designed at CERN to provide the required magnetic field. This toroid will comprise eight, one meter wide and twenty one meter long, racetrack coils. The system is sized 5.2 m in diameter and 25 m in length. Its peak magnetic field is 5.4 T with a stored e...
International Nuclear Information System (INIS)
Riemer, B.W.; Miki, Nobuharu; Hashizume, Takashi.
1988-06-01
This report describes the comparison of TF coil stresses in NET and FER. The analyses focus on the straight part of the inner legs, since it is this part of the coil which most directly influences the radial build of the machine. NET's TF coils are wedged together and the centering force on each of the coils is reacted by toroidal compression of the inner legs. The forces that act out of the plane of each coil are reacted by friction between adjacent inner legs such that the set of legs behave much like a cylinder under torsion. In contrast, the FER device employs a bucking cylinder to react the centering load, which incurs a penalty in radial thickness, and the out of plane forces are reacted by the use of shear keys between adjacent inner legs. Analytic techniques or ''hand methods'' have been used to estimate and compare the strains and stresses at the inner leg mid-plane section resulting from both in-plane and out-of-plane magnetic forces. Such techniques forced a more thorough understanding of the structural behavior of the coils. The amount of effort in analyzing the NET coil is greater than for FER as the reaction of centering load in its wedged design is more complex, and because it was found that friction plays a very important part in determining the coil stresses. The FER coil is simpler in this regard, and a ''hand estimation'' of its coil stresses was straightfoward. In this report, the program written to perform these analyses is also described. It was desired to provide new capabilities to the original TF stress subroutine in TRESCODE and to review and improve it where possible. This has been accomplished, and subroutines are now available for use in JAERI's system code, TRESCODE. It is hoped that the inner leg radial thickness can be better optimized by using the program. (author)
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
Hairy AdS black holes with a toroidal horizon in 4D Einstein-nonlinear omega-model system
Czech Academy of Sciences Publication Activity Database
Astorino, M.; Canfora, F.; Giacomini, A.; Ortaggio, Marcello
2018-01-01
Roč. 776, 10 January (2018), s. 236-241 ISSN 0370-2693 R&D Projects: GA ČR GB14-37086G Institutional support: RVO:67985840 Keywords : AdS black holes * nonlinear sigma model Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.807, year: 2016 http://www.sciencedirect.com/science/ article /pii/S0370269317309437
Hairy AdS black holes with a toroidal horizon in 4D Einstein-nonlinear omega-model system
Czech Academy of Sciences Publication Activity Database
Astorino, M.; Canfora, F.; Giacomini, A.; Ortaggio, Marcello
2018-01-01
Roč. 776, 10 January (2018), s. 236-241 ISSN 0370-2693 R&D Projects: GA ČR GB14-37086G Institutional support: RVO:67985840 Keywords : AdS black holes * nonlinear sigma model Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.807, year: 2016 http://www.sciencedirect.com/science/article/pii/S0370269317309437
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.
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 ...
MHD simulation study of compact toroid injection into magnetized plasmas
Energy Technology Data Exchange (ETDEWEB)
Suzuki, Yoshio; Kishimoto, Yasuaki [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Hayashi, Takaya [National Inst. for Fusion Science, Toki, Gifu (Japan)
2000-06-01
To understand the fuelling process in a fusion device by a compact toroid (CT) plasmoid injection method, we have carried out MHD numerical simulations where a spheromak-like CT (SCT) is injected into a magnetized target plasma region. So far, we revealed that the penetration depth of the SCT plasma becomes shorter than that estimated from the conducting sphere (CS) model, because in the simulation the Lorentz force of the target magnetic field sequentially decelerates the injected SCT while in the CS model only the magnetic pressure force acts as the deceleration mechanism. In this study, we represent the new theoretical model where the injected SCT is decelerated by both the magnetic pressure force and the magnetic tension force (we call it the non-slipping sphere (NS) model) and investigate in detail the deceleration mechanism of the SCT by comparison with simulation results. As a result, it is found that the decrease of the SCT kinetic energy in the simulation coincides with that in the NS model more than in the CS model. It means that not only the magnetic pressure force but also the magnetic tension force acts as the deceleration mechanism of the SCT. Furthermore, it is revealed that magnetic reconnection between the SCT magnetic field and the target magnetic field plays a role to relax the SCT deceleration. (author)
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.
RF breakdown by toroidal helicons
Indian Academy of Sciences (India)
Abstract. Bounded whistlers are well-known for their efficient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohy- drodynamic (EMHD) frequency ...
RF breakdown by toroidal helicons
Indian Academy of Sciences (India)
Bounded whistlers are well-known for their efﬁcient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohydrodynamic (EMHD) frequency regime is fed to ...
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)
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...
Field Model: An Object-Oriented Data Model for Fields
Moran, Patrick J.
2001-01-01
We present an extensible, object-oriented data model designed for field data entitled Field Model (FM). FM objects can represent a wide variety of fields, including fields of arbitrary dimension and node type. FM can also handle time-series data. FM achieves generality through carefully selected topological primitives and through an implementation that leverages the potential of templated C++. FM supports fields where the nodes values are paired with any cell type. Thus FM can represent data where the field nodes are paired with the vertices ("vertex-centered" data), fields where the nodes are paired with the D-dimensional cells in R(sup D) (often called "cell-centered" data), as well as fields where nodes are paired with edges or other cell types. FM is designed to effectively handle very large data sets; in particular FM employs a demand-driven evaluation strategy that works especially well with large field data. Finally, the interfaces developed for FM have the potential to effectively abstract field data based on adaptive meshes. We present initial results with a triangular adaptive grid in R(sup 2) and discuss how the same design abstractions would work equally well with other adaptive-grid variations, including meshes in R(sup 3).
A full wave code for ion cyclotron waves in toroidal plasmas
International Nuclear Information System (INIS)
Brambilla, M.
1996-02-01
The code TORIC solves the finite Larmor radius wave equations in the ion cyclotron frequency range in arbitrary axisymmetric toroidal geometry. The model used describes the compressional and torsional Alfven waves (or, depending on the parallel phase velocity, the kinetic counterpart of the latter), and ion Bernstein waves excited by mode conversion near the first ion cyclotron harmonic. In the ion response the broadening of the absorption regions due to the finite width of the cyclotron resonance of individual ions in toroidal geometry is taken into account. The parallel component of the wave electric field is evaluated on the same footing as the transverse ones; the response of the electrons includes Landau damping, Transit Time damping and the mixed term. The numerical approach uses a spectral representation of the solution in the poloidal angle θ, and cubic finite elements in the radial variable ψ. Great flexibility is provided in the way ion Bernstein waves excited by mode conversion are damped when their wavelength becomes comparable with the ion Larmor radius, in the regularization of Alfven resonances, and in the treatment of the outer plasma layers. As an option, we have also implemented the Order Reduction Algorithm, which provides a particularly fast, yet accurate evaluation of the power deposition profiles in toroidal geometry. Thee present report describes the model and its numerical implementation, and provides the information needed to use the code. A few examples illustrating applications of TORIC are also included. (orig.)
Kumar, Umesh; Ganesh, R.; Saxena, Y. C.; Thatipamula, Shekar G.; Sathyanarayana, K.; Raju, Daniel
2017-10-01
In magnetized toroidal devices without rotational transform also known as Simple Magnetized Torus (SMT). The device BETA at the IPR is one such SMT with a major radius of 45 cm, minor radius of 15 cm and a maximum toroidal field of 0.1 Tesla. Understanding confinement in such helical configurations is an important problem both for fundamental plasma physics and for Tokamak edge physics. In a recent series of experiments it was demonstrated experimentally that the mean plasma profiles, fluctuation, flow and turbulence depend crucially on the parallel connection length, which was controlled by external vertical field. In the present work, we report our experimental findings, wherein we measure the particle confinement time for hot cathode discharge and ECRH discharge, with variation in parallel connection length. As ECRH plasma don't have mean electric field and hence the poloidal rotation of plasma is absent. However, in hot cathode discharge, there exist strong poloidal flows due to mean electric field. An experimental comparison of these along with theoretical model with variation in connection length will be presented. We also present experimental measurements of variation of plasma confinement time with mass as well as the ratio of vertical field to toroidal magnetic field.
A direct calculation of current drive in toroidal geometry
International Nuclear Information System (INIS)
Wright, J.C.; Phillips, C.K.; Bonoli, P.T.
1998-01-01
The magnitude and radial profiles of noninductive currents driven by fast magnetosonic waves in tokamaks have been calculated directly from the wave-induced quasilinear flux in a toroidal geometry and a Green's function for the current. An expression for the quasilinear flux has been derived which accounts for coupling between modes in the spectrum of waves launched from the antenna. A Fokker-Planck code for the Green's function and a full wave code for the electric field in the quasilinear flux are used to evaluate the current in a specified toroidal geometry
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)
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.
Low-frequency fluctuations in a pure toroidal magnetized plasma
Indian Academy of Sciences (India)
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. The experimental investiga- tion of time-averaged plasma parameter reveals that their profiles remain insensitive to ion mass and suggests that ...
Theoretical studies of non inductive current drive in compact toroids
Farengo, R; Lifschitz, AF; Caputi, KI; Arista, NR; Clemente, RA
Three non inductive current drive methods that can be applied to compact toroids axe studied. The use of neutral beams to drive current in field reversed configurations and spheromaks is studied using a Monte Carlo code that includes a complete ionization package and follows the exact particle
Improved model predictive control of resistive wall modes by error field estimator in EXTRAP T2R
Setiadi, A. C.; Brunsell, P. R.; Frassinetti, L.
2016-12-01
Many implementations of a model-based approach for toroidal plasma have shown better control performance compared to the conventional type of feedback controller. One prerequisite of model-based control is the availability of a control oriented model. This model can be obtained empirically through a systematic procedure called system identification. Such a model is used in this work to design a model predictive controller to stabilize multiple resistive wall modes in EXTRAP T2R reversed-field pinch. Model predictive control is an advanced control method that can optimize the future behaviour of a system. Furthermore, this paper will discuss an additional use of the empirical model which is to estimate the error field in EXTRAP T2R. Two potential methods are discussed that can estimate the error field. The error field estimator is then combined with the model predictive control and yields better radial magnetic field suppression.
Toroidal and poloidal momentum transport studies in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Tala, T [Association EURATOM-Tekes, VTT, PO Box 1000, FIN-02044 VTT (Finland); Crombe, K [Department of Applied Physics, Ghent University (Belgium); Vries, P C de [EURATOM/UKAEA Fusion Association, Culham Science Centre, Oxon, OX14 3DB (United Kingdom)] (and others)
2007-12-15
The present status of understanding of toroidal and poloidal momentum transport in tokamaks is presented in this paper. Similar energy confinement and momentum confinement times, i.e. {tau}{sub E}/{tau}{sub {phi}} {approx} 1 have been reported on several tokamaks. It is more important though, to study the local transport both in the core and edge plasma separately as, for example, in the core plasma, a large scatter in the ratio of the local effective momentum diffusivity to the ion heat diffusivity {chi}{sub {phi}}{sub eff}/{chi}{sub i,eff} among different tokamaks can be found. For example, the value of effective Prandtl number is typically around {chi}{sub {phi}}{sub eff}/{chi}{sub i,eff} {approx} 0.2 on JET while still {tau}{sub E}/{tau}{sub {phi}} {approx} 1 holds. Perturbative NBI modulation experiments on JET have shown, however, that a Prandtl number {chi}{sub {phi}}{sub /}{chi}{sub i} of around 1 is valid if there is an additional, significant inward momentum pinch which is required to explain the amplitude and phase behaviour of the momentum perturbation. The experimental results, i.e. the high Prandtl number and pinch, are in good qualitative and to some extent also in quantitative agreement with linear gyro-kinetic simulations. In contrast to the toroidal momentum transport which is clearly anomalous, the poloidal velocity is usually believed to be neo-classical. However, experimental measurements on JET show that the carbon poloidal velocity can be an order of magnitude above the predicted value by the neo-classical theory within the ITB. These large measured poloidal velocities, employed for example in transport simulations, significantly affect the calculated radial electric field and therefore the E x B flow shear and hence modify and can significantly improve the simulation predictions. Several fluid turbulence codes have been used to identify the mechanism driving the poloidal velocity to such high values. CUTIE and TRB turbulence codes and also
Toroidal and poloidal momentum transport studies in tokamaks
Tala, T.; Crombé, K.; de Vries, P. C.; Ferreira, J.; Mantica, P.; Peeters, A. G.; Andrew, Y.; Budny, R.; Corrigan, G.; Eriksson, A.; Garbet, X.; Giroud, C.; Hua, M.-D.; Nordman, H.; Naulin, V.; Nave, M. F. F.; Parail, V.; Rantamäki, K.; Scott, B. D.; Strand, P.; Tardini, G.; Thyagaraja, A.; Weiland, J.; Zastrow, K.-D.; Contributors, JET-EFDA
2007-12-01
The present status of understanding of toroidal and poloidal momentum transport in tokamaks is presented in this paper. Similar energy confinement and momentum confinement times, i.e. τE/τphi ≈ 1 have been reported on several tokamaks. It is more important though, to study the local transport both in the core and edge plasma separately as, for example, in the core plasma, a large scatter in the ratio of the local effective momentum diffusivity to the ion heat diffusivity χphieff/χi,eff among different tokamaks can be found. For example, the value of effective Prandtl number is typically around χphieff/χi,eff ≈ 0.2 on JET while still τE/τphi ≈ 1 holds. Perturbative NBI modulation experiments on JET have shown, however, that a Prandtl number χphi/χi of around 1 is valid if there is an additional, significant inward momentum pinch which is required to explain the amplitude and phase behaviour of the momentum perturbation. The experimental results, i.e. the high Prandtl number and pinch, are in good qualitative and to some extent also in quantitative agreement with linear gyro-kinetic simulations. In contrast to the toroidal momentum transport which is clearly anomalous, the poloidal velocity is usually believed to be neo-classical. However, experimental measurements on JET show that the carbon poloidal velocity can be an order of magnitude above the predicted value by the neo-classical theory within the ITB. These large measured poloidal velocities, employed for example in transport simulations, significantly affect the calculated radial electric field and therefore the E × B flow shear and hence modify and can significantly improve the simulation predictions. Several fluid turbulence codes have been used to identify the mechanism driving the poloidal velocity to such high values. CUTIE and TRB turbulence codes and also the Weiland model predict the existence of an anomalous poloidal velocity, peaking in the vicinity of the ITB and driven dominantly
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.
Investigation of diocotron modes in toroidally trapped electron plasmas using non-destructive method
Lachhvani, Lavkesh; Pahari, Sambaran; Sengupta, Sudip; Yeole, Yogesh G.; Bajpai, Manu; Chattopadhyay, P. K.
2017-10-01
Experiments with trapped electron plasmas in a SMall Aspect Ratio Toroidal device (SMARTEX-C) have demonstrated a flute-like mode represented by oscillations on capacitive (wall) probes. Although analogous to diocotron mode observed in linear electron traps, the mode evolution in toroids can have interesting consequences due to the presence of in-homogeneous magnetic field. In SMARTEX-C, the probe signals are observed to undergo transition from small, near-sinusoidal oscillations to large amplitude, non-linear "double-peaked" oscillations. To interpret the wall probe signal and bring forth the dynamics, an expression for the induced current on the probe for an oscillating charge is derived, utilizing Green's Reciprocation Theorem. Equilibrium position, poloidal velocity of the charge cloud, and charge content of the cloud, required to compute the induced current, are estimated from the experiments. Signal through capacitive probes is thereby computed numerically for possible charge cloud trajectories. In order to correlate with experiments, starting with an intuitive guess of the trajectory, the model is evolved and tweaked to arrive at a signal consistent with experimentally observed probe signals. A possible vortex like dynamics is predicted, hitherto unexplored in toroidal geometries, for a limited set of experimental observations from SMARTEX-C. Though heuristic, a useful interpretation of capacitive probe data in terms of charge cloud dynamics is obtained.
The problem of evolution of toroidal plasma equilibrium
International Nuclear Information System (INIS)
Kostomarov, D.; Zaitsev, F.; Shishkin, A.
1999-03-01
This paper is devoted to an advanced mathematical model for a self-consistent description of the evolution of free boundary toroidal plasmas, with a description of numerical algorithms for the solution of the appropriate non-linear system of integro-differential equations, and discussion of some results from the model. (author)
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
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.
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
Transporting the first ATLAS toroid
Maximilien Brice
2004-01-01
The first coil for the ATLAS toroid magnet is transported from its assembly hall at the CERN Meyrin site to the storage hall above the ATLAS cavern. This involves driving the massive transportation vehicle first through the Meyrin site and then across a main road only metres from the France-Swiss border. Eight magnets in total will be transported in this way before being lowered into the experimental cavern where they will be mounted in a huge ring surrounding the detector.
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
Initial temperature profiles of the PDX inner toroidal limiter
International Nuclear Information System (INIS)
Ulrickson, M.; Kugel, H.W.
1983-01-01
The temperature profiles resulting from plasma operation on the PDX vertical, large area, inner toroidal limiter have been measured during both ohmic and neutral beam heated discharges using a scanning infrared camera. An asymmetric double peaked temperature profile is seen after neutral beam heated discharges. Disruptions in ohmically heated discharges are found to be preceded by a single peaked deposition and succeeded by a initially symmetric double peaked deposition. The results were compared with the Schmidt model for scrapeoff at a toroidal limiter and it was found that the measured double peaked temperature profiles yielded scrape-off lengths consistent with previous measurements
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
Renormalization of gauge fields models
International Nuclear Information System (INIS)
Becchi, C.; Rouet, A.; Stora, R.
1974-01-01
A new approach to gauge field models is described. It is based on the Bogoliubov-Parasiuk-Hepp-Zimmermann (BPHZ) renormalization scheme making extensive use of the quantum action principle, and the Slavnov invariance. The quantum action principle being first summarized in the framework of the BPHZ is then applied to a global symmetry problem. The symmetry property of the gauge field Lagrangians in the tree approximation is exhibited, and the preservation of this property at the quantum level is discussed. The main results relative to the Abelian and SU(2) Higgs-Kibble models are briefly reviewed [fr
International Nuclear Information System (INIS)
Garabedian, P.R.
1991-08-01
At high collisionality the neoclassical theory of transport in tokamaks predicts that the electron confinement time τ e will exceed the ion confinement time τ i by a factor roughly equal to the square root of the mass ratio m i /m e . If the energy confinement time τ E is calculated from the normalized particle confinement time τ through division by an emperical factor of three times the magnetic field strength B, then the theoretical confinement time of the ions exceeds experimental measurements by a factor of as much as three. The prediction that the electron confinement time will be two orders of magnitude larger is referred to as anomalous electron transport. We assert that the anomaly can be explained by imposing a strict requirement of quasineutrality to determine the electric potential instead of allowing it to be found from conservation of momentum. Numerical evidence for this contention is provided by performing Monte Carlo calculations based on a fast new computer code called TRAN
Toroidal and poloidal momentum transport studies in JET
Tala, T.; Andrew, Y.; Crombé, K.; de Vries, P. C.; Garbet, X.; Hawkes, N.; Nordman, H.; Rantamäki, K.; Strand, P.; Thyagaraja, A.; Weiland, J.; Asp, E.; Baranov, Y.; Challis, C.; Corrigan, G.; Eriksson, A.; Giroud, C.; Hua, M.-D.; Jenkins, I.; Knoops, H. C. M.; Litaudon, X.; Mantica, P.; Naulin, V.; Parail, V.; Zastrow, K.-D.; contributors, JET-EFDA
2007-08-01
This paper reports on the recent studies of toroidal and poloidal momentum transport in JET. The ratio of the global energy confinement time to the momentum confinement is found to be close to τE/τphi = 1 except for the low density or low collisionality discharges where the ratio is τE/τphi = 2-3. On the other hand, local transport analysis of around 40 discharges shows that the ratio of the local effective momentum diffusivity to the ion heat diffusivity is χphi/χi ap 0.1-0.4 (averaged over the radial region r/a = 0.4-0.7) rather than unity, as expected from the global confinement times and used often in ITER predictions. The apparent discrepancy in the global and local momentum versus ion heat transport can be at least partly explained by the fact that momentum confinement within edge pedestal is worse than that of the ion heat and thus, momentum pedestal is weaker than that of ion temperature. In addition, while the ion temperature profile shows clearly strong profile stiffness, the toroidal velocity profile does not exhibit stiffness, as exemplified here during a giant ELM crash. Predictive transport simulations with the self-consistent modelling of toroidal velocity using the Weiland model and GLF23 also confirm that the ratio χphi/χi ap 0.4 reproduces the core toroidal velocity profiles well and similar accuracy with the ion temperature profiles. Concerning poloidal velocities on JET, the experimental measurements show that the carbon poloidal velocity can be an order of magnitude above the neo-classical estimate within the ITB. This significantly affects the calculated radial electric field and therefore, the E × B flow shear used for example in transport simulations. Both the Weiland model and GLF23 reproduce the onset, location and strength of the ITB well when the experimental poloidal velocity is used while they do not predict the formation of the ITB using the neo-classical poloidal velocity in time-dependent transport simulation. The most
Turbulence simulations of blob formation and radial propagation in toroidally magnetized plasmas
DEFF Research Database (Denmark)
Garcia, O.E.; Naulin, V.; Nielsen, A.H.
2006-01-01
of particles and heat, which is coupled to a scrape-off layer with linear damping terms for all dependent variables corresponding to transport along open magnetic field lines. The formation of blob structures is related to profile variations caused by bursting in the global turbulence level, which is due......Two- dimensional numerical fluid turbulence simulations demonstrating the formation and radial propagation of blob structures in toroidally magnetized plasmas are presented and analysed in detail. A salient feature of the model is a linearly unstable edge plasma region with localized sources...
Saddle-splay screening and chiral symmetry breaking in toroidal nematics
Koning, Vinzenz; van Zuiden, Benjamin C.; Kamien, Randall D.; Vitelli, Vincenzo
2013-01-01
We present a theoretical study of director fields in toroidal geometries with degenerate planar boundary conditions. We find spontaneous chirality: despite the achiral nature of nematics the director configuration show a handedness if the toroid is thick enough. In the chiral state the director field displays a double twist, whereas in the achiral state there is only bend deformation. The critical thickness increases as the difference between the twist and saddle-splay moduli grows. A positiv...
Goya - an MHD equilibrium code for toroidal plasmas
International Nuclear Information System (INIS)
Scheffel, J.
1984-09-01
A description of the GOYA free-boundary equilibrium code is given. The non-linear Grad-Shafranov equation of ideal MHD is solved in a toroidal geometry for plasmas with purely poloidal magnetic fields. The code is based on a field line-tracing procedure, making storage of a large amount of information on a grid unnecessary. Usage of the code is demonstrated by computations of equi/libria for the EXTRAP-T1 device. (Author)
CPRF/ZTH toroidal conducting shell design and fabrication considerations
International Nuclear Information System (INIS)
Ballard, E.O.; Gomez, T.; Smith, R.L.; Weldon, D.M.
1987-01-01
The authors discuss design in progress of a new generation Reversed Field Pinch (RFP) machine to be fabricated and assembled at Los Alamos National Laboratory during FY 86-92. The Confinement Physics Research Facility (CPRF) houses the front-end ZTH torus. The ZTH consists oof an Inconel 625 vacuum liner supported by an external electrically conducting shell. The shell also supports 48 toroidal field coils that are mounted to the shells external surface
A model unified field equation
International Nuclear Information System (INIS)
Perring, J.K.; Skyrme, T.H.R.
1994-01-01
The classical solutions of a unified field theory in a two-dimensional space-time are considered. This system, a model of a interacting mesons and baryons, illustrates how the particle can be built from a wave-packet of mesons and how reciprocally the meson appears as a tightly bound combination of particle and antiparticle. (author). 6 refs
Toroidal hollow-core microcavities produced by self-rolling of strained polymer bilayer films
Luchnikov, V.; Kumar, K.; Stamm, M.
2008-03-01
Hollow-core toroidal micro-cavities are obtained by self-rolling of double-layer (polyvinyl pyridine/polystyrole) polymer films. Rolling of the bilayer is due to preferential swelling of polyvinyl pyridine in water solution of dodecyl benzene sulfonic acid. The tube formation proceeds from a circular opening in the film made by photolithography or by mechanical scratching. Toroid equilibrium dimensions are determined by the balance of the elastic energy relaxation via the film scrolling and the work of the in-plane stretching that is due to increasing radius of the toroid. The principle features of the micro-toroid formation process are captured by a simple analytical model. The inner walls of the cavities can be made metal coated. For this aim, the polymer bilayer can be metallized by vacuum sputtering prior to lithographic patterning and rolling of the bilayer. The toroids with metallic inner surfaces are promising for the future research as IR-frequency range resonators.
Nonideal magnetohydrodynamic instabilities and toroidal magnetic confinement
Energy Technology Data Exchange (ETDEWEB)
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.
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)
Field testing of bioenergetic models
International Nuclear Information System (INIS)
Nagy, K.A.
1985-01-01
Doubly labeled water provides a direct measure of the rate of carbon dioxide production by free-living animals. With appropriate conversion factors, based on chemical composition of the diet and assimilation efficiency, field metabolic rate (FMR), in units of energy expenditure, and field feeding rate can be estimated. Validation studies indicate that doubly labeled water measurements of energy metabolism are accurate to within 7% in reptiles, birds, and mammals. This paper discusses the use of doubly labeled water to generate empirical models for FMR and food requirements for a variety of animals
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
Advanced Toroidal Facility vacuum vessel stress analyses
International Nuclear Information System (INIS)
Hammonds, C.J.; Mayhall, J.A.
1987-01-01
The complex geometry of the Advanced 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
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
Rath, N.; Onofri, M.; Dettrick, S. A.; Barnes, D. C.; Romero, J.
2017-04-01
We present a linear, one-parameter model for rigid displacement of a toroidally symmetric plasma. When the feedback control is feasible, plasma inertia can be neglected, and the instability growth rate is proportional to wall resistivity. We benchmark the linear model against non-linear, hybrid simulations of an axially unstable, beam-driven field-reversed configuration to fix the free parameter of the model. The resulting parameter-free model is validated using linear and non-linear closed-loop simulations with active feedback control by voltage-controlled coils. In closed loop simulations, the predictions of the parameter-free linear model agree satisfactory with the non-linear results. Implications for the feedback control of the positional instability in experiments are discussed. The presented model has been used to guide the design of the feedback control hardware in the C-2W experiment.
Toroidal regularization of the guiding center Lagrangian
Burby, J. W.; Ellison, C. L.
2017-11-01
In the Lagrangian theory of guiding center motion, an effective magnetic field B*=B +(m /e )v∥∇× b appears prominently in the equations of motion. Because the parallel component of this field can vanish, there is a range of parallel velocities where the Lagrangian guiding center equations of motion are either ill-defined or very badly behaved. Moreover, the velocity dependence of B* greatly complicates the identification of canonical variables and therefore the formulation of symplectic integrators for guiding center dynamics. This letter introduces a simple coordinate transformation that alleviates both these problems simultaneously. In the new coordinates, the Liouville volume element is equal to the toroidal contravariant component of the magnetic field. Consequently, the large-velocity singularity is completely eliminated. Moreover, passing from the new coordinate system to canonical coordinates is extremely simple, even if the magnetic field is devoid of flux surfaces. We demonstrate the utility of this approach in regularizing the guiding center Lagrangian by presenting a new and stable one-step variational integrator for guiding centers moving in arbitrary time-dependent electromagnetic fields.
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.
Correlation Models for Temperature Fields
North, Gerald R.
2011-05-16
This paper presents derivations of some analytical forms for spatial correlations of evolving random fields governed by a white-noise-driven damped diffusion equation that is the analog of autoregressive order 1 in time and autoregressive order 2 in space. The study considers the two-dimensional plane and the surface of a sphere, both of which have been studied before, but here time is introduced to the problem. Such models have a finite characteristic length (roughly the separation at which the autocorrelation falls to 1/e) and a relaxation time scale. In particular, the characteristic length of a particular temporal Fourier component of the field increases to a finite value as the frequency of the particular component decreases. Some near-analytical formulas are provided for the results. A potential application is to the correlation structure of surface temperature fields and to the estimation of large area averages, depending on how the original datastream is filtered into a distribution of Fourier frequencies (e.g., moving average, low pass, or narrow band). The form of the governing equation is just that of the simple energy balance climate models, which have a long history in climate studies. The physical motivation provided by the derivation from a climate model provides some heuristic appeal to the approach and suggests extensions of the work to nonuniform cases.
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…
Toroidal field coils for the PDX machine
International Nuclear Information System (INIS)
Bushnell, C.W.
1975-01-01
This paper describes the engineering design features of the TF coils for the PDX machine. Included are design details of the electrical insulation, water cooling, and coil segment joint which allows access to the central machine area. A discussion of the problems anticipated in the manufacture and the planned solutions are presented
Curvature-induced electrostatic drift modes in a toroidal plasma
International Nuclear Information System (INIS)
Venema, M.
1985-01-01
This thesis deals with a number of problems in the theory of linear stability of a hot, fully ionized plasma immersed in a strong magnetic field. The most widely used system to magnetically confine a plasma is the tokamak. This is a toroidal, current carrying device with a strong, externally imposed, magnetic field. The author discusses the linear theory of unstable, low-frequency waves in the gradient region, restricted to electrostatic waves. In that case the resulting radial fluxes of particles and energy are due to electric cross-field drifts. In the presence of magnetic fluctuations and small-scale reconnection phenomena, radial transport could also be predominantly along field lines. At present, it is not clear which of the two mechanisms is the dominant feature of the observed anomalous transport. First, the author introduces the theory of drift waves in toroidal geometry. Next, the electrostratic drift modes in toroidal geometry (weakly collisional regime), the equations for low-frequency waves in the strongly collisional regime and the electrostatic drift modes (strongly collisional regime) are discussed. (Auth.)
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
Shear-dependant toroidal vortex flow
Energy Technology Data Exchange (ETDEWEB)
Khorasani, Nariman Ashrafi; Haghighi, Habib Karimi [Payame Noor University, Tehran (Iran, Islamic Republic of)
2013-01-15
Pseudoplastic circular Couette flow in annulus is investigated. The flow viscosity is dependent on the shear rate, which directly affects the conservation equations that are solved in the present study by the spectral method in the present study. The pseudoplastic model adopted here is shown to be a suitable representative of nonlinear fluids. Unlike the previous studies, where only the square of shear rate term in the viscosity expression was considered to ease the numerical manipulations, in the present study takes the term containing the quadratic power into account. The curved streamlines of the circular Couette flow can cause a centrifugal instability leading to toroidal vortices, known as Taylor vortices. It is further found that the critical Taylor number becomes lower as the pseudoplastic effect increases. Comparison with existing measurements on pseudoplastic circular Couette flow results in good agreement.
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.
Optical measurements and analytical modeling of magnetic field generated in a dieletric target
Yafeng, BAI; Shiyi, ZHOU; Yushan, ZENG; Yihan, LIANG; Rong, QI; Wentao, LI; Ye, TIAN; Xiaoya, LI; Jiansheng, LIU
2018-01-01
Polarization rotation of a probe pulse by the target is observed with the Faraday rotation method in the interaction of an intense laser pulse with a solid target. The rotation of the polarization plane of the probe pulse may result from a combined action of fused silica and diffused electrons. After the irradiation of the main pulse, the rotation angle changed significantly and lasted ∼2 ps. These phenomena may imply a persistent magnetic field inside the target. An analytical model is developed to explain the experimental observation. The model indicates that a strong toroidal magnetic field is induced by an energetic electron beam. Meanwhile, an ionization channel is observed in the shadowgraph and extends at the speed of light after the irradiation of the main beam. The formation of this ionization channel is complex, and a simple explanation is given.
Toroidal Variable-Line-Space Gratings: The Good, the Bad and The Ugly
West, Edward A.; Kobayashi, Ken; Cirtain, Jonathan; Gary, Allen; Davis, John; Reader, Joseph
2009-01-01
Toroidal variable-line-space (VLS) gratings are an important factor in the design of an efficient VUV solar telescope that will measure the CIV (155nm) and MgII (280nm) emissions lines in the Sun's transition region. In 1983 Kita and Harada described spherical VLS gratings but the technology to commercially fabricate these devices is a recent development, especially for toroidal surfaces. This paper will describe why this technology is important in the development of the Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program (the good), the delays due to the conversion between the TVLS grating design and the optical fabrication (the bad), and finally the optical testing, alignment and tolerancing of the gratings (the ugly). The Solar Ultraviolet Magnetograph Investigation, SUMI, has been reported in several papers since this program began in 2000. The emphasis of this paper is to describe SUMI's Toroidal Variable-Line-Space (TVLS) gratings. These gratings help SUMI meet its scientific goals which require both high spectral resolution and high optical efficiency for magnetic field measurements in the vacuum ultraviolet wavelength band of the solar spectrum (the good). Unfortunately, the technology readiness level of these gratings has made their implementation difficult, especially for a sounding rocket payload (the bad). Therefore, this paper emphasizes the problems and solutions that were developed to use these gratings in SUMI (the ugly). Section 2 contains a short review of the scientific goals of SUMI and why this mission is important in the understanding of the 3D structure of the magnetic field on the Sun. The flight hardware that makes up the SUMI payload is described in Section 3 with emphasis on those components that affect the TVLS gratings. Section 4 emphasizes the alignment, testing and optical modeling that were developed to optimize the performance of these gratings.
Dynamics of spheromak-like compact toroids in a drift tube
International Nuclear Information System (INIS)
Suzuki, Y.; Kishimoto, Y.; Hayashi, T.
2001-01-01
In order to supply plasma fuel confined in spheromak-like compact toroids (SCTs) to a fusion device, the SCTs must be successfully guided through a drift tube region, in which they might be influenced by the magnetic field leaking from the fusion device. To reveal the SCT dynamics in a drift tube, MHD numerical simulations, where the SCTs are accelerated in a co-axial perfectly conducting cylinder with an external magnetic field, are carried out. In addition, the effect of an extended central electrode is examined by changing the length of the inner conducting cylinder. It is revealed that the SCT penetration depth is shorter than that estimated from the conventional conducting sphere model and that the SCTs are further decelerated by extending the inner conducting cylinder. These results are consistent with the results of the compact toroid injection experiment performed on the TEXT Upgrade tokamak. Finally, the deceleration mechanism of the SCTs is discussed by comparing the simulation result with the proposed theoretical model. (author)
Dynamics of spheromak-like compact toroids in a drift tube
Suzuki, Y.; Hayashi, T.; Kishimoto, Y.
2001-06-01
In order to supply plasma fuel confined in spheromak-like compact toroids (SCTs) to a fusion device, the SCTs must be successfully guided through a drift tube region, in which they might be influenced by the magnetic field leaking from the fusion device. To reveal the SCT dynamics in a drift tube, MHD numerical simulations, where the SCTs are accelerated in a co-axial perfectly conducting cylinder with an external magnetic field, are carried out. In addition, the effect of an extended central electrode is examined by changing the length of the inner conducting cylinder. It is revealed that the SCT penetration depth is shorter than that estimated from the conventional conducting sphere model and that the SCTs are further decelerated by extending the inner conducting cylinder. These results are consistent with the results of the compact toroid injection experiment performed on the TEXT Upgrade tokamak. Finally, the deceleration mechanism of the SCTs is discussed by comparing the simulation result with the proposed theoretical model.
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
The Swarm Initial Field Model for the 2014 geomagnetic field
DEFF Research Database (Denmark)
Olsen, Nils; Hulot, Gauthier; Lesur, Vincent
2015-01-01
Data from the first year of ESA's Swarm constellation mission are used to derive the Swarm Initial Field Model (SIFM), a new model of the Earth's magnetic field and its time variation. In addition to the conventional magnetic field observations provided by each of the three Swarm satellites...... agreement (up to at least degree 60) with recent field models derived from CHAMP data, providing an initial validation of the quality of the Swarm magnetic measurements. Use of gradient data improves the determination of both the static field and its secular variation, with the mean misfit for East...
Transport and dynamics in toroidal fusion systems. Report of second year progress, 1993--1994
International Nuclear Information System (INIS)
Schnack, D.D.
1994-01-01
In this document the author describes an extension of the spatial gridding techniques to an MHD model suitable for the description of the dynamics of toroidal fusion devices. Since the dominant MHD modes in these devices have relatively long toroidal wavelength, the toroidal coordinate is approximated with finite Fourier series. The unstructured, triangular mesh is used to describe the details of the poloidal geometry. With some exceptions, the hydrodynamic variables are treated in a manner analogous to that used in CFD. These quantities (mass, energy, and momentum) are volume based densities that satisfy scalar or vector conservation laws. The electromagnetic variables (the magnetic flux density B and the electric current density J) are area based densities that satisfy pseudo-vector conservation laws, and have no counterpart in fluid dynamics. These variables are also constrained to remain solenoidal. These quantities are represented on the triangular mesh in a new manner that is an extension of that used on rectangular, structured meshes. In this work the author has chosen to solve the primitive MHD equations in order to make the resulting codes and techniques more generally applicable to problems beyond the narrow scope of tokamak plasmas. The temporal stiffness problems inherent in this description of tokamak dynamics that motivate the reduced MHD model are addressed here with the semi-implicit method of time integration. Finally, the author remarks that, while the present work deals strictly with the MHD equations, other volume based fluid descriptions, such as diffusive transport could easily be adapted to these techniques and coupled with the description of the electromagnetic field presented here
Toroidal coupling in the kinetic response to edge magnetic perturbations
Spizzo, G.; Agostini, M.; Scarin, P.; White, R. B.; Schmitz, O.; Spolaore, M.; Terranova, D.; Veranda, M.; Vianello, N.
2017-12-01
The magnetic topology of the stochastic edge of a helical reversed-field pinch, with helicity m/n , shows to be deeply influenced by higher harmonics (m +/- 1)/ n , with the same n, due to toroidal coupling. As a consequence, by measuring kinetic quantities in a particular θ, φ location, one can incur in substantial errors or mis-interpretations of the kinetic plasma response: only a full 3D coverage of θ, φ angles can reveal the real topology of the plasma. This can be a caveat for MP application in tokamaks, because it shows that toroidal and poloidal sidebands, though smaller than the base mode by a factor ∼ \
Compact toroid injection experiment in JFT-2M
International Nuclear Information System (INIS)
Ogawa, T.; Fukumoto, N.; Nagata, M.
2001-01-01
Compact toroid (CT)injection experiments with H-mode plasmas were carried out for the first time in JFT-2M. The soft x-ray emission profile shows central penetration of CT in H-mode plasma heated by 1.2 MW NBI as well as in OH plasmas, with toroidal magnetic field of 0.8 T. The line-averaged electron density rapidly increased by Δn-bar e ∝0.2x10 19 m -3 at a rate of 4x10 21 m -3 /s in H-mode and the fuelling efficiency was roughly 20%.The asymmetrical radial profile in the soft x-ray emission was produced for ∝ 50 μs by the central penetration of CT. (author)
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)
Control and monitoring of the Tore Supra toroidal superconducting coils
International Nuclear Information System (INIS)
Prou, M.
1989-07-01
Light nuclei controlled fusion reactions are seen as a possible way to produce nuclear energy. For this reason, the interest in hot plasma researches in tokamaks has increased. The Tore Supra main characteristic is related to the superconducting magnet coils. They allow a suitable energy balance, however, they require an accurate and preventive fault detection. The Tore Supra machine and the different methods to detect a transition (from superconducting to normal mode) in the toroidal coils are described. The voltage of the coils, the pressure of the helium superfluid at 1.8 K and the electric current in the circuit parallel resistances, are measured. A computer aided control system allows the toroidal field monitoring (current in the coils, fault detection). The superconducting magnet configuration chosen for Tore Supra seems to be suitable for future large Tokamak devices [fr
Broadening of the lower hybrid kparallel spectrum by toroidal effects
International Nuclear Information System (INIS)
Barbato, E.; Romanelli, F.
1990-01-01
Toroidal geometry affects the evolution of k parallel (the component of the wave vector parallel to the magnetic field) along the lower hybrid, (LH) wave trajectories. In this paper such variations are investigated both analytically and numerically. The main parameters governing this phenomenon are found and how k parallel upshift can occur within this scheme is elucidated. As a figure of merit a k parallel - upshift factor is defined and discussed in a dimensionless parameter space in which all the LH experiments can be represented. Finally, a discussion of whether and when toroidal effects can fill the gap between the high phase velocity of the injected LH waves and the electron thermal velocity is presented by analyzing different experimental situations
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.
Toroidally symmetric/asymmetric effect on the divertor flux due to neon/nitrogen seeding in LHD
Directory of Open Access Journals (Sweden)
H. Tanaka
2017-08-01
Full Text Available Toroidal distributions of divertor particle flux during neon (Ne and nitrogen (N2 seeded discharges were investigated in the Large Helical Device (LHD. By using 14 toroidally distributed divertor probe arrays, which were positioned at radially inner side where the divertor flux concentrates in the inward-shifted magnetic axis configuration, it is found that Ne puffing leads to toroidally quasi-uniform reduction of divertor particle fluxes; whereas toroidally localized reductions were observed with N2 puffing. The toroidally asymmetric reduction pattern with N2 puffing is strongly related to the magnetic field structure around the N2 puffing port. Assuming that nitrogen particles do not recycle, EMC3-EIRENE simulation shows similar reduction pattern with the experiment around the N2 puffing port.
Relationships between solid spherical and toroidal harmonics
Majic, Matt; Ru, Eric C. Le
2018-01-01
We derive new relationships expressing solid spherical harmonics as series of toroidal harmonics and vice versa. The expansions include regular and irregular spherical harmonics, ring and axial toroidal harmonics of even and odd parity about the plane of the torus. The expansion coefficients are given in terms of a recurrence relation. As an example application we apply one of the expansions to express the potential of a charged conducting torus on a basis of spherical harmonics.
The Swarm Initial Field Model for the 2014 Geomagnetic Field
Olsen, Nils; Hulot, Gauthier; Lesur, Vincent; Finlay, Christopher C.; Beggan, Ciaran; Chulliat, Arnaud; Sabaka, Terence J.; Floberghagen, Rune; Friis-Christensen, Eigil; Haagmans, Roger
2015-01-01
Data from the first year of ESA's Swarm constellation mission are used to derive the Swarm Initial Field Model (SIFM), a new model of the Earth's magnetic field and its time variation. In addition to the conventional magnetic field observations provided by each of the three Swarm satellites, explicit advantage is taken of the constellation aspect by including east-west magnetic intensity gradient information from the lower satellite pair. Along-track differences in magnetic intensity provide further information concerning the north-south gradient. The SIFM static field shows excellent agreement (up to at least degree 60) with recent field models derived from CHAMP data, providing an initial validation of the quality of the Swarm magnetic measurements. Use of gradient data improves the determination of both the static field and its secular variation, with the mean misfit for east-west intensity differences between the lower satellite pair being only 0.12 nT.
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...
International Nuclear Information System (INIS)
Noterdaeme, J.M.
1983-05-01
Applying the constraints to the design of a helical axis stellarator we find a limit on the combination of toroidal field, current density and major radius. Another major constraint for this concept is the ability to obtain the plasma physics parameters dictated by similarity considerations. This depends on the heating method used. A minimum scale experiment with 2 periods and no linkage of the toroidal and poloidal coils, would have a major radius of 1.2m, a toroidal field of 3.5T and 2MW of ECRH power (for β = 1% nu 2 = 10)
Mercury's Internal Magnetic Field: Modeling Core Fields with Smooth Inversions
Uno, H.; Johnson, C. L.; Anderson, B. J.; Korth, H.; Purucker, M. E.; Solomon, S. C.
2008-12-01
MESSENGER's second flyby (M2) of Mercury on 6 October 2008 will provide significantly improved geographical sampling of the planet's internal magnetic field over previous measurements. Latitudinal coverage and spacecraft altitudes will be similar to those during MESSENGER's first encounter (M1), but the spacecraft trajectory will be displaced by about 180° in longitude, yielding the first magnetic measurements in the western hemisphere. We investigate spatial structure in Mercury's internal magnetic field by applying methods from inverse theory to construct low-degree-and-order spherical harmonic models. External fields predicted by a parameterized magnetospheric model are subtracted from the vector field observations. The approach takes into account noise contributions from long-wavelength uncertainties in the external field models, unexplained short-wavelength features, and spacecraft attitude errors. We investigate the effect of different regularization (smoothness) constraints on our inversions. Analyses of data from M1 and the two Mariner 10 flybys that penetrated the magnetosphere yield a preferred spherical harmonic solution to degree and order eight with the centered, axial dipole term g10 dominating. The model shows structure at low and mid-latitude regions near the flybys. Terms predicted by an analytical model for long- wavelength crustal fields - namely g10, g30 and g32 - are present, but their relative amplitudes are not consistent with such a field. We conclude that structure in our models is dominated by core, rather than by crustal, fields. We also investigate, through simulations, field morphologies that are recoverable while the spacecraft is in orbit about Mercury, under the assumption that the long-wavelength contributions from external sources can be accurately modeled and removed. Although the elliptical orbit of MESSENGER will impede the recovery of southern hemisphere structure, we obtain excellent recovery of the dipole field and of
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.
1976-01-01
Two different types of high β toroidal pinch experiments, STP and CCT, have been done to study the confinement of the plasma produced by theta-pinch. The STP is an axisymmetric toroidal pinch of high β tokamak type, while the CCT is 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 not so different plasma temperatures and densities. The observed laser scattering temperature and density is about 50 eV and 4 x 10 15 /cm 3 , respectively, when the filling pressure is 5 m torr. In the experiment of STP, 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 distruption 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 the stable plasma confinement is achieved. The energy confinement time of the CCT is found to be about 35 μsec. (orig.) [de
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
Talebi, Nahid; Guo, Surong; van Aken, Peter A.
2018-01-01
Dipole selection rules underpin much of our understanding in characterization of matter and its interaction with external radiation. However, there are several examples where these selection rules simply break down, for which a more sophisticated knowledge of matter becomes necessary. An example, which is increasingly becoming more fascinating, is macroscopic toroidization (density of toroidal dipoles), which is a direct consequence of retardation. In fact, dissimilar to the classical family of electric and magnetic multipoles, which are outcomes of the Taylor expansion of the electromagnetic potentials and sources, toroidal dipoles are obtained by the decomposition of the moment tensors. This review aims to discuss the fundamental and practical aspects of the toroidal multipolar moments in electrodynamics, from its emergence in the expansion set and the electromagnetic field associated with it, the unique characteristics of their interaction with external radiations and other moments, to the recent attempts to realize pronounced toroidal resonances in smart configurations of meta-molecules. Toroidal moments not only exhibit unique features in theory but also have promising technologically relevant applications, such as data storage, electromagnetic-induced transparency, unique magnetic responses and dichroism.
Simulated and experimental compression of a compact toroid
Energy Technology Data Exchange (ETDEWEB)
Johnson, J N; Hwang, D Q; Horton, R D; Evans, R W; Owen, J M
2009-05-06
We present simulation results and experimental data for the compression of a compact toroid by a conducting nozzle without a center electrode. In both simulation and experiment, the flow of the plasma is greatly obstructed by even modest magnetic fields. A simple mechanism for this obstruction is suggested by our simulations. In particular, the configuration of the plasmoid's magnetic field plays a significant role in the success of the experiment. We analyze two types of plasma configurations under compression and demonstrate that the results from the simulations matches those from the experiments, and that the mechanism predicts the different behaviors observed in the two cases.
Mean-field models and exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P.G. [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)
1998-06-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Mean-field models and exotic nuclei
International Nuclear Information System (INIS)
Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W.; Rutz, K.; Reinhard, P.G.
1998-01-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Observations of toroidal and poloidal rotation in the high beta tokamak Torus II
International Nuclear Information System (INIS)
Kostek, C.A.
1983-01-01
The macroscopic rotation of plasma in a toroidal containment device is an important feature of the equilibrium. Toroidal and poloidal rotation in the high beta tokamak Torus II is measured experimentally by examining the Doppler shift of the 4685.75 A He II line emitted from the plasma. The toroidal flow at an average velocity of 1.6 x 10 6 cm/sec, a small fraction of the ion thermal speed, moves in the same direction as the toroidal plasma current. The poloidal flow follows the ion diamagnetic current direction, also at an average speed of 1.6 x 10 6 cm/sec. In view of certain ordering parameters, the toroidal flow is compared with predictions from neoclassical theory in the collosional, Pfirsch-Schluter regime. The poloidal motion, however results from an E x B drift in a positive radial electric field, approaching a stable ambipolar state. This radial electric field is determined from theory by using the measured poloidal velocity. Mechanisms for the time evolution of rotation are also examined. It appears that the circulation damping is governed by a global decay of the temperature and density gradients which, in turn, may be functions of radiative cooling, loss of equilibrium due to external field decay, or the emergence of a growing instability, occasionally observed in CO 2 interferometry measurements
Collisionless two-fluid theory of toroidal ηi stability
International Nuclear Information System (INIS)
Mondt, J.; Weiland, J.
1989-01-01
A collisionless two-fluid theory based on a fourteen-moment generalization of the 'double-adiabatic' equations is developed to lowest order in the Larmor radius parameter, and applied to derive the toroidal η i stability boundary for all values of the ratio of the density gradient scale length divided by the field curvature length. The present model is an improvement over existing collisional two-fluid models in view of the collisionless nature of the η i instability, while retaining the advantage over kinetic theory of the practability of mode-coupling simulations. The linear stability boundary, linear growth rate and real frequency agree fairly accurately with draft-kinetic theory
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
Pinch effects and chaotic motion in toroidal confinement devices
Energy Technology Data Exchange (ETDEWEB)
Spizzo, G.; White, R. B.; Cappello, S.; Marrelli, L.; Sattin, F.
2007-07-01
Particle transport in toroidal confinement devices is often described in terms of a diffusion constant and an inward pinch velocity: this phenomenological description can be justified by a probabilistic approach (random walk) that simplifies the particle dynamics when the orbits are small enough compared to the system size. This results in a diffusive expression for particle flux. Then, the convective part of the particle flux can be related, for example, to spatial inhomogeneities in temperature or field curvature. When magnetic chaos is present, but the system is not too far from the stochastic threshold, diffusion and pinch can be actually an expression of the sub diffusive nature of the transport, brought about by the presence of a spectrum of long-distance Levy flights. This effect is shown by numerical modelling of the magnetic structure and associated particle transport in conditions relevant for the reversed-field pinch experiment RFX-mod based at Consorzio RFX, Padova. Simulations reproduce the particle motion through guiding center calculations of particle orbits embedded in the magnetic topology, obtained by 3D MHD simulations (code SpeCyl). Results have been used to produce the probability distribution functions (p.d.f.) of jump lengths and waiting times, providing the kernel to integrate in the Montroll equation, which governs the evolution of particle density in the Continuous-time random walk (CTRW) approach. This means that we obtain a transport equation using the knowledge of the kernel which comes directly from the actual particle dynamics. The difference of behavior between trapped and passing particles has also been considered, and has a relevance comparable to sub diffusion in determining the pinch effect. Similar results can be applied to other systems with chaos induces particle transport, e.g. electron transport in Tokamaks. This work was partially supported by DoE contract No. DE-FG03-94ER54271. (Author)
Absence of toroidal moments in 'aromagnetic' anthracene
Energy Technology Data Exchange (ETDEWEB)
Alborghetti, S; Coey, J M D [School of Physics, Trinity College, Dublin 2 (Ireland); Puppin, E; Brenna, M; Pinotti, E; Zanni, P [Dipartimento di Fisica, Politecnico di Milano, Milano (Italy)], E-mail: alborgs@tcd.ie
2008-06-15
Colloidal suspensions of anthracene and other aromatic compounds have been shown to respond to a magnetic field as if they possessed a permanent magnetic moment. This phenomenon was named 'aromagnetism' by Spartakov and Tolstoi, and it was subsequently attributed to the interaction of an electric toroidal moment with a time-varying magnetic field. However, there has been no independent confirmation of the original work. Here, we have selected purified anthracene crystallites which respond to a low magnetic field and investigate how this response depends on the gradient and the time derivative of the field. We conclude that the anomaly cannot be attributed to a toroidal interaction but is due to a constant magnetic moment of the particles. Close examinations using magnetometry and scanning electron microscopy reveal metallic clusters of Fe and Ni up to a few hundred nanometres in size embedded in the anomalous crystallites. These inclusions represent 1.8 ppm by weight of the sample. The observed presence of ferromagnetic inclusions in the ppm range is sufficient to explain the anomalous magnetic properties of micron-sized anthracene crystals, including the reported optical properties of the colloidal suspensions.
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
Theory and application of maximum magnetic energy in toroidal plasmas
International Nuclear Information System (INIS)
Chu, T.K.
1992-02-01
The magnetic energy in an inductively driven steady-state toroidal plasma is a maximum for a given rate of dissipation of energy (Poynting flux). A purely resistive steady state of the piecewise force-free configuration, however, cannot exist, as the periodic removal of the excess poloidal flux and pressure, due to heating, ruptures the static equilibrium of the partitioning rational surfaces intermittently. The rupture necessitates a plasma with a negative q'/q (as in reverse field pinches and spheromaks) to have the same α in all its force-free regions and with a positive q'/q (as in tokamaks) to have centrally peaked α's
Fluctuations and stability in the Advanced Toroidal Facility (ATF) torsatron
International Nuclear Information System (INIS)
Harris, J.H.; Charlton, L.A.; Bell, J.D.; Bigelow, T.S.; Carreras, B.A.; Colchin, R.J.; Crume, E.C.; Dominguez, N.; Dunlap, J.L.; Dyer, G.R.; England, A.C.; Glowienka, J.C.; Hillis, D.L.; Hiroe, S.; Horton, L.D.; Howe, H.C.; Isler, R.C.; Jernigan, T.C.; Leboeuf, J.N.; Lee, D.K.; Lynch, V.E.; Lyon, J.F.; Menon, M.M.; Murakami, M.; Rasmussen, D.A.; Uckan, T.; Wilgen, J.B.; Wing, W.R.; Bell, G.L.; Crocker, N.A.; Hanson, G.R.; Thomas, C.E.; Wade, M.R.; Ritz, C.P.
1990-01-01
We present the results of experimental and theoretical studies of fluctuations and instabilities in the ATF torsatron, a type of stellarator. Measurements of globally coherent magnetic fluctuations in high-β plasmas with narrow pressure profiles produced by a field error show evidence of self-stabilization ('second stability'); the trends are compatible with theoretical analysis of self-stabilization of resistive curvature-driven instabilities, but there are discrepancies between the absolute experimental and theoretical fluctuation amplitudes. Fluctuation measurements in plasma with broad pressure profiles reveal new phenomena--specifically, toroidally localized magnetic fluctuations, whose amplitudes increase with plasma pressure, and coherent density fluctuations with significant radial width
Geostatistical methods applied to field model residuals
DEFF Research Database (Denmark)
Maule, Fox; Mosegaard, K.; Olsen, Nils
consists of measurement errors and unmodelled signal), and is typically assumed to be uncorrelated and Gaussian distributed. We have applied geostatistical methods to analyse the residuals of the Oersted(09d/04) field model [http://www.dsri.dk/Oersted/Field_models/IGRF_2005_candidates/], which is based......The geomagnetic field varies on a variety of time- and length scales, which are only rudimentary considered in most present field models. The part of the observed field that can not be explained by a given model, the model residuals, is often considered as an estimate of the data uncertainty (which...... on 5 years of Ørsted and CHAMP data, and includes secular variation and acceleration, as well as low-degree external (magnetospheric) and induced fields. The analysis is done in order to find the statistical behaviour of the space-time structure of the residuals, as a proxy for the data covariances...
RESICALC: Magnetic field modeling program
International Nuclear Information System (INIS)
Silva, J.M.
1992-12-01
RESICALC, Version 1.0, is a Microsoft Windows application that describes the magnetic field environment produced by user-defined arrays of transmission lines, distribution lines, and custom conductors. These arrays simulate specific situations that may be encountered in real-world community settings. RESICALC allows the user to define an area or ''world'' that contains the transmission and/or distribution lines, user-defined conductors, and locations of residences. The world contains a ''reference grid'' within which RESICALC analyzes the magnetic field environment due to all conductors within the world. Unique physical parameters (e.g., conductor height and spacing) and operating characteristics can be assigned to all electrical conductors. RESICALC's output is available for the x, y, z axis separately, the resultant (the three axes added in quadrature), and the major axis, each in three possible formats: a three-dimensional map of the magnetic field, two dimensional-contours, and as a table with statistical values. All formats may be printed, accompanied by a three-dimensional view of the world the user has drawn. The view of the world and the corresponding three-dimensional field map may be adjusted to the elevation and rotation angle of the user's preference
Commissioning of the magnetic field in the ATLAS muon spectrometer
Arnaud, M; Bergsma, F; Bobbink, G; Bruni, A; Chevalier, L; Ennes, P; Fleischmann, P; Fontaine, M; Formica, A; Gautard, V; Groenstege, H; Guyot, C; Hart, R; Kozanecki, W; Iengo, P; Legendre, M; Nikitina, T; Perepelkin, E; Ponsot, P; Richardson, A; Vorozhtsov, A; Vorozthsov, S
2008-01-01
ATLAS is a general-purpose detector at the 14 TeV proton-proton Large Hadron Collider at CERN. The muon spectrometer will operate in the magnetic field provided by a large, eight-coil barrel toroid magnet bracketed by two smaller toroidal end-caps. The toroidal field is non-uniform, with an average value of about 0.5 T in the barrel region, and is monitored using three-dimensional Hall sensors which must be accurate to 1 mT. The barrel coils were installed in the cavern from 2004 to 2006, and recently powered up to their nominal current. The Hall-sensor measurements are compared with calculations to validate the magnetic models, and used to reconstruct the position and shape of the coil windings. Field perturbations by the magnetic materials surrounding the muon spectrometer are found in reasonable agreement with finite-element magnetic-field simulations.
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.
Toroidally Resolved Structure of Divertor Heat Flux in RMP H-mode Discharges on DIII-D
International Nuclear Information System (INIS)
Jakubowski, M.W.; Evans, T.E.; Fenstermacher, M.E.; Lasnier, C.J.; Wolf, R.C.; Baylor, Larry R.; Boedo, J.A.; Burrell, K.H.; DeGrassie, J.S.; Gohil, P.; Mordijck, S.; Laengner, R.; Leonard, A.W.; Moyer, R.A.; Petrie, T.W.; Petty, C.C.; Pinsker, R.I.; Rhodes, T.L.; Schaffer, M.J.; Schmitz, O.; Snyder, P.B.; Stoschus, H.; Osborne, T.H.; Orlov, D.M.; Unterberg, Ezekial A.; Watkins, J.G.
2011-01-01
As shown on DIII-D edge localized modes (ELMs) can be either completely eliminated or mitigated with resonant magnetic perturbation (RMP) fields. Two infrared cameras, separated 105 degrees toroidally, were used to make simultaneous measurements of ELM heat loads with high frame rates. Without the RMP fields ELMs display a variety of different heat load dynamics and a range of toroidal variability that is characteristic of their 3D structure. Comparing radial averages there is no asymmetry between two toroidal locations. With RMP-mitigated ELMs, the variability in the radially averaged power loads is significantly reduced and toroidal asymmetries in power loads are introduced. In addition to RMP ELM suppression scenarios an RMP scenario with only very small ELMs and very good confinement has been achieved.
Uncertainty Quantification in Geomagnetic Field Modeling
Chulliat, A.; Nair, M. C.; Alken, P.; Meyer, B.; Saltus, R.; Woods, A.
2017-12-01
Geomagnetic field models are mathematical descriptions of the various sources of the Earth's magnetic field, and are generally obtained by solving an inverse problem. They are widely used in research to separate and characterize field sources, but also in many practical applications such as aircraft and ship navigation, smartphone orientation, satellite attitude control, and directional drilling. In recent years, more sophisticated models have been developed, thanks to the continuous availability of high quality satellite data and to progress in modeling techniques. Uncertainty quantification has become an integral part of model development, both to assess the progress made and to address specific users' needs. Here we report on recent advances made by our group in quantifying the uncertainty of geomagnetic field models. We first focus on NOAA's World Magnetic Model (WMM) and the International Geomagnetic Reference Field (IGRF), two reference models of the main (core) magnetic field produced every five years. We describe the methods used in quantifying the model commission error as well as the omission error attributed to various un-modeled sources such as magnetized rocks in the crust and electric current systems in the atmosphere and near-Earth environment. A simple error model was derived from this analysis, to facilitate usage in practical applications. We next report on improvements brought by combining a main field model with a high resolution crustal field model and a time-varying, real-time external field model, like in NOAA's High Definition Geomagnetic Model (HDGM). The obtained uncertainties are used by the directional drilling industry to mitigate health, safety and environment risks.
The Evolution of the Solar Magnetic Field: A Comparative Analysis of Two Models
McMichael, K. D.; Karak, B. B.; Upton, L.; Miesch, M. S.; Vierkens, O.
2017-12-01
Understanding the complexity of the solar magnetic cycle is a task that has plagued scientists for decades. However, with the help of computer simulations, we have begun to gain more insight into possible solutions to the plethora of questions inside the Sun. STABLE (Surface Transport and Babcock Leighton) is a newly developed 3D dynamo model that can reproduce features of the solar cycle. In this model, the tilted bipolar sunspots are formed on the surface (based on the toroidal field at the bottom of the convection zone) and then decay and disperse, producing the poloidal field. Since STABLE is a 3D model, it is able to solve the full induction equation in the entirety of the solar convection zone as well as incorporate many free parameters (such as spot depth and turbulent diffusion) which are difficult to observe. In an attempt to constrain some of these free parameters, we compare STABLE to a surface flux transport model called AFT (Advective Flux Transport) which solves the radial component of the magnetic field on the solar surface. AFT is a state-of-the-art surface flux transport model that has a proven record of being able to reproduce solar observations with great accuracy. In this project, we implement synthetic bipolar sunspots into both models, using identical surface parameters, and run the models for comparison. We demonstrate that the 3D structure of the sunspots in the interior and the vertical diffusion of the sunspot magnetic field play an important role in establishing the surface magnetic field in STABLE. We found that when a sufficient amount of downward magnetic pumping is included in STABLE, the surface magnetic field from this model becomes insensitive to the internal structure of the sunspot and more consistent with that of AFT.
A combinatorial wind field model
DEFF Research Database (Denmark)
Soleimanzadeh, Maryam; Wisniewski, Rafal; Sloth, Christoffer
2010-01-01
of ordinary dierential equations (ODE). Considering some assumptions on the ow model (e.g. steadiness), the sys- tem can be approximated by a linear n dimensional system. Partitioning the state space into cells is performed by dening Lyapunov function sets, such that each cell is the region between two......This report is the deliverable 2.4 in the project Distributed Control of Large-Scale Oshore Wind Farms with the acronym Aeolus. The objective of this deliverable is to provide an understanding of the wind eld model and dynamic variations superimposed on the mean eld. In this report a dynamical...... model is developed for the wind ow in a wind farm based on nite volume method. Afterwards the model is transferred into a discrete framework called combinatorial, which determines the future behavior of the discrete system. In this regard, the dynamical model is de- rived and it is explained in terms...
Alien wavelength modeling tool and field trial
DEFF Research Database (Denmark)
Sambo, N.; Sgambelluri, A.; Secondini, M.
2015-01-01
A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been...
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)
Effect of loss cone on confinement in toroidal helical device
International Nuclear Information System (INIS)
Itoh, K.; Itoh, S.-I.; Fukuyama, A.; Hanatani, K.
1988-12-01
Analytical estimation is given on the loss cone in the toroidal helical devices in the presence of the radial electric field and the modulation of the helical ripple. The minimum energy of particles entering the loss cone is calculated. The modulation is not always effective in reducing the loss in the presence of the radial electric field. The plasma loss due to the loss cone is estimated in the collisionless limit. The radial electric field is estimated in the presence of the loss cone. It is found that the transition to the solution with positive radial electric field, which is necessary to achieve the high-ion-temperature mode, becomes difficult. This difficulty is large for the systems with the small helical ripple. (author)
Building analytical three-field cosmological models
Santos, J. R. L.; Moraes, P. H. R. S.; Ferreira, D. A.; Neta, D. C. Vilar
2018-02-01
A difficult task to deal with is the analytical treatment of models composed of three real scalar fields, as their equations of motion are in general coupled and hard to integrate. In order to overcome this problem we introduce a methodology to construct three-field models based on the so-called "extension method". The fundamental idea of the procedure is to combine three one-field systems in a non-trivial way, to construct an effective three scalar field model. An interesting scenario where the method can be implemented is with inflationary models, where the Einstein-Hilbert Lagrangian is coupled with the scalar field Lagrangian. We exemplify how a new model constructed from our method can lead to non-trivial behaviors for cosmological parameters.
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.
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
Toroidal Ampere-Faraday Equations Solved Simultaneously with CQL3D Fokker-Planck Time-Evolution
Harvey, R. W. (Bob); Petrov, Yu. V. (Yuri); Forest, C. B.; La Haye, R. J.
2017-10-01
A self-consistent, time-dependent toroidal electric field calculation is a key feature of a complete 3D Fokker-Planck kinetic distribution radial transport code for f(v,theta,rho,t). We discuss benchmarking and first applications of an implementation of the Ampere-Faraday equation for the self-consistent toroidal electric field, as applied to (1) resistive turn on of applied electron cyclotron current in the DIII-D tokamak giving initial back current adjacent to the direct CD region and having possible NTM stabilization implications, and (2) runaway electron production in tokamaks due to rapid reduction of the plasma temperature as occurs in pellet injection, massive gas injection, or a plasma disruption. Our previous results assuming a constant current density (Lenz' Law) model showed that prompt ``hot-tail runaways'' dominated ``knock-on'' and Dreicer ``drizzle'' runaways; we perform full-radius modeling and examine modifications due to the more complete Ampere-Faraday solution. Presently, the implementation relies on a fixed shape eqdsk, and this limitation will be addressed in future work. Research supported by USDOE FES award ER54744.
Schellart, W. P.; Moresi, L.
2013-01-01
We present numerical subduction models to investigate overriding plate deformation at subduction zones. All models show forearc shortening, resulting predominantly from shear stresses at the subduction zone interface and opposite-sense mantle shear stresses at the base of the forearc lithosphere.
The CHAOS-4 geomagnetic field model
DEFF Research Database (Denmark)
Olsen, Nils; Lühr, H.; Finlay, Chris
2014-01-01
determined. More than 14 yr of data from the satellites Ørsted, CHAMP and SAC-C, augmented with magnetic observatory monthly mean values have been used for this model. Maximum spherical harmonic degree of the static (lithospheric) field is n = 100. The core field is expressed by spherical harmonic expansion...... high-degree lithospheric field part is solely determined from low-altitude CHAMP satellite observations taken during the last 2 yr (2008 September-2010 September) of the mission. We obtain a good agreement with other recent lithospheric field models like MF7 for degrees up to n = 85, confirming...
Directory of Open Access Journals (Sweden)
Ap Kuiroukidis
2018-01-01
Full Text Available We consider a generalized Grad–Shafranov equation (GGSE in a triangularity-deformed axisymmetric toroidal coordinate system and solve it numerically for the generic case of ITER-like and JET-like equilibria with non-parallel flow. It turns out that increase of the triangularity improves confinement by leading to larger values of the toroidal beta and the safety factor. This result is supported by the application of a criterion for linear stability valid for equilibria with flow parallel to the magnetic field. Also, the parallel flow has a weaker stabilizing effect.
Perturbation treatment of the longitudinal coupling impedance of a toroidal beam tube
International Nuclear Information System (INIS)
Hahn, H.; Tepikian, S.
1991-01-01
A simple analytical expression for the longitudinal coupling impedance of a toroidal beam tube below the resonance region has been derived by expanding the electromagnetic fields of the toroidal beam tube in a power series in curvature and substituting directly into Maxwell's equations. The resulting expression consists of the impedance of the straight beam pipe plus a correction terms due to the curvature. It has been verified that this result gives excellent agreement to the exact solution below the first resonance. 5 refs., 2 figs., 3 tabs
Modelling electricity forward markets by ambit fields
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole; Fred Espen Benth, Fred Espen; Veraart, Almut
This paper proposes a new modelling framework for electricity forward markets, which is based on ambit fields. The new model can capture many of the stylised facts observed in energy markets. One of the main differences to the traditional models lies in the fact that we do not model the dynamics......, but the forward price directly, where we focus on models which are stationary in time. We give a detailed account on the probabilistic properties of the new model and we discuss martingale conditions and change of measure within the new model class. Also, we derive a model for the spot price which is obtained...... from the forward model through a limiting argument....
Toroidal Dipole Moment of the Lightest Neutralino in the MSSM
International Nuclear Information System (INIS)
Cabral-Rosetti, L G; Mondragon, M; Perez, E Reyes
2011-01-01
In order to characterize one of the most favored candidates for dark matter, we calculate the anapole form factor of the lightest neutralino in the Minimal Supersymmetric Standard Model (MSSM) at the one-loop level. As a Majorana fermion, this particle only shows one electromagnetic property, the toroidal dipole moment, which is directly related to the anapole form factor. We obtain the result analitically in terms of two- and three-points Passarino-Veltman scalar functions and evaluate it for a given spectrum of supersymmetric masses and matrix elements. This work is part of a broader project still in progress.
Phase Field Modeling Using PetIGA
Vignal, Philippe
2013-06-01
Phase field modeling has become a widely used framework in the computational material science community. Its ability to model different problems by defining appropriate phase field parameters and relating it to a free energy functional makes it highly versatile. Thermodynamically consistent partial differential equations can then be generated by assuming dissipative dynamics, and setting up the problem as one of minimizing this free energy. The equations are nonetheless challenging to solve, and having a highly efficient and parallel framework to solve them is necessary. In this work, a brief review on phase field models is given, followed by a short analysis of the Phase Field Crystal Model solved with Isogeometric Analysis us- ing PetIGA. We end with an introduction to a new modeling concept, where free energy functions are built with a periodic equilibrium structure in mind.
Effect of continuous eigenvalue spectrum on plasma transport in toroidal systems
International Nuclear Information System (INIS)
Yamagishi, Tomejiro
1993-03-01
The effect of the continuous eigenvalue of the Vlasov equation on the cross field ion thermal flux is investigated. The continuum contribution due to the toroidal drift resonance is found to play an important role in ion transport particularly near the edge, which may apply to the interpretation of the sharp increase of ion heat conductivity near the periphery observed in large tokamaks. (author)
Field Models in Electricity and Magnetism
Barba, Paolo Di; Wiak, S
2008-01-01
Covering the development of field computation in the past forty years, Field Models in Electricity and Magnetism intends to be a concise, comprehensive and up-to-date introduction to field models in electricity and magnetism, ranging from basic theory to numerical applications. The approach assumed throughout the whole book is to solve field problems directly from partial differential equations in terms of vector quantities. Theoretical issues are illustrated by practical examples. In particular, a single example is solved by different methods so that, by comparison of results, limitations and advantages of the various methods are made clear. The subjects of the synthesis of fields and of the optimal design of devices, which are growing in research and so far have not been adequately covered in textbooks, are developed in addition to more classical subjects of analysis. Topics covered include: vector fields: electrostatics, magnetostatics, steady conduction; analytical methods for solving boundary-value probl...
Reconstructing bidimensional scalar field theory models
International Nuclear Information System (INIS)
Flores, Gabriel H.; Svaiter, N.F.
2001-07-01
In this paper we review how to reconstruct scalar field theories in two dimensional spacetime starting from solvable Scrodinger equations. Theree different Schrodinger potentials are analyzed. We obtained two new models starting from the Morse and Scarf II hyperbolic potencials, the U (θ) θ 2 In 2 (θ 2 ) model and U (θ) = θ 2 cos 2 (In(θ 2 )) model respectively. (author)
Flow field mapping in data rack model
Directory of Open Access Journals (Sweden)
Matěcha J.
2013-04-01
Full Text Available The main objective of this study was to map the flow field inside the data rack model, fitted with three 1U server models. The server model is based on the common four-processor 1U server. The main dimensions of the data rack model geometry are taken fully from the real geometry. Only the model was simplified with respect to the greatest possibility in the experimental measurements. The flow field mapping was carried out both experimentally and numerically. PIV (Particle Image Velocimetry method was used for the experimental flow field mapping, when the flow field has been mapped for defined regions within the 2D/3D data rack model. Ansys CFX and OpenFOAM software were used for the numerical solution. Boundary conditions for numerical model were based on data obtained from experimental measurement of velocity profile at the output of the server mockup. This velocity profile was used as the input boundary condition in the calculation. In order to achieve greater consistency of the numerical model with experimental data, the numerical model was modified with regard to the results of experimental measurements. Results from the experimental and numerical measurements were compared and the areas of disparateness were identified. In further steps the obtained proven numerical model will be utilized for the real geometry of data racks and data.
Magnetic field structure of experimental high beta tokamak equilibria
International Nuclear Information System (INIS)
Deniz, A.V.
1986-01-01
The magnetic field structure of several low and high β tokamaks in the Columbia High Beta Tokamak (HBT) was determined by high-impedance internal magnetic probes. From the measurement of the magnetic field, the poloidal flux, toroidal flux, toroidal current, and safety factor are calculated. In addition, the plasma position and cross-sectional shape are determined. The extent of the perturbation of the plasma by the probe was investigated and was found to be acceptably small. The tokamaks have major radii of approx.0.24 m, minor radii of approx.0.05 m, toroidal plasma current densities of approx.10 6 A/m 2 , and line-integrated electron densities of approx.10 20 m -2 . The major difference between the low and high β tokamaks is that the high β tokamak was observed to have an outward shift in major radius of both the magnetic center and peak of the toroidal current density. The magnetic center moves inward in major radius after 20 to 30 μsec, presumably because the plasma maintains major radial equilibrium as its pressure decreases from radiation due to impurity atoms. Both the equilibrium and the production of these tokamaks from a toroidal field stabilized z-pinch are modeled computationally. One tokamak evolves from a state with low β features, through a possibly unstable state, to a state with high β features
A Hamiltonian five-field gyrofluid model
Energy Technology Data Exchange (ETDEWEB)
Keramidas Charidakos, I.; Waelbroeck, F. L.; Morrison, P. J. [Institute for Fusion Studies and Department of Physics, The University of Texas at Austin, Austin, TX 78712 (United States)
2015-11-15
A Lie-Poisson bracket is presented for a five-field gyrofluid model, thereby showing the model to be Hamiltonian. The model includes the effects of magnetic field curvature and describes the evolution of the electron and ion gyro-center densities, the parallel component of the ion and electron velocities, and the ion temperature. The quasineutrality property and Ampère's law determine, respectively, the electrostatic potential and magnetic flux. The Casimir invariants are presented, and shown to be associated with five Lagrangian invariants advected by distinct velocity fields. A linear, local study of the model is conducted both with and without Landau and diamagnetic resonant damping terms. Stability criteria and dispersion relations for the electrostatic and the electromagnetic cases are derived and compared with their analogs for fluid and kinetic models.
Compact toroid injection system for JFT-2M
Energy Technology Data Exchange (ETDEWEB)
Fukumoto, N. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan)]. E-mail: fukumotn@eng.u-hyogo.ac.jp; Ogawa, H. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Nagata, M. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Uyama, T. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Shibata, T. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Kashiwa, Y. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Suzuki, S. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Kusama, Y. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan)
2006-11-15
The compact toroid (CT) injection system for JFT-2M is composed of a CT injector, a gas delivery and vacuum system, a power supply system, and a diagnostics system. In particular, the power supply system delivers high performance for CT formation and acceleration. The CT formation capacitor bank unit achieved a formation current of 350 kA with a rise time less than 10 {mu}s. Although the CT acceleration bank units are equipped with 14 ignitron switches instead of gap switches to attenuate the discharge noise level, an acceleration current of 400 kA with a short rise time of 9 {mu}s is controlled within a jitter of much less than 1 {mu}s. The resulting CT velocity and mass density satisfy the requirements for CT penetration into the tokamak plasma core at a toroidal field of 1 T. This CT injection system is thus suitable for CT injection in a middle-sized tokamak plasma such as the JFT-2M tokamak.
Pareto optimal design of sectored toroidal superconducting magnet for SMES
International Nuclear Information System (INIS)
Bhunia, Uttam; Saha, Subimal; Chakrabarti, Alok
2014-01-01
Highlights: • The optimization approach minimizes both the magnet size and necessary cable length of a sectored toroidal SMES unit. • Design approach is suitable for low temperature superconducting cable suitable for medium size SMES unit. • It investigates coil parameters with respect to practical engineering aspects. - Abstract: A novel multi-objective optimization design approach for sectored toroidal superconducting magnetic energy storage coil has been developed considering the practical engineering constraints. The objectives include the minimization of necessary superconductor length and torus overall size or volume, which determines a significant part of cost towards realization of SMES. The best trade-off between the necessary conductor length for winding and magnet overall size is achieved in the Pareto-optimal solutions, the compact magnet size leads to increase in required superconducting cable length or vice versa The final choice among Pareto optimal configurations can be done in relation to other issues such as AC loss during transient operation, stray magnetic field at outside the coil assembly, and available discharge period, which is not considered in the optimization process. The proposed design approach is adapted for a 4.5 MJ/1 MW SMES system using low temperature niobium–titanium based Rutherford type cable. Furthermore, the validity of the representative Pareto solutions is confirmed by finite-element analysis (FEA) with a reasonably acceptable accuracy
Theory and MHD simulation of fuelling process by Compact Toroid (CT) injection
International Nuclear Information System (INIS)
Suzuki, Y.; Hayashi, T.; Kishimoto, Y.
2001-01-01
The fuelling process by a spheromak-like compact toroid (SCT) injection is investigated by using MHD numerical simulations, where the SCT is injected into a magnetized target plasma region corresponding to a fusion device. In our previous study, the theoretical model to determine the penetration depth of the SCT into the target region has been proposed based on the simulation results, in which the SCT is decelerated not only by the magnetic pressure force but also by the magnetic tension force. However, since both ends of the target magnetic field are fixed on the boundary wall in the simulation, the deceleration caused by the magnetic tension force would be overestimated. In this study, the dependence of the boundary condition of the target magnetic field on the SCT penetration process is examined. From these results, the theoretical model we have proposed is improved to include the effect that the wave length of the target magnetic field bent by the SCT penetration expands with the Alfven velocity. In addition, by carrying out the simulation with the torus domain, it is confirmed that the theoretical model is applicable to estimate the penetration depth of the SCT under such conditions. Furthermore, the dependence of the injection position (the side injection and the top/bottom injection) on the penetration process is examined. (author)
Shielding and synchrotron radiation in toroidal waveguide
Directory of Open Access Journals (Sweden)
G. V. Stupakov
2003-03-01
Full Text Available We develop a new approach to the calculation of the synchrotron radiation in a toroidal vacuum chamber. Using a small parameter ϵ=sqrt[a/R], where a is the characteristic size of the cross section of the toroid and R is the bending radius, we simplify Maxwell’s equations assuming that the characteristic frequency of the modes ω∼c/aϵ and neglect terms of higher order in ϵ. For a rectangular cross section of the waveguide, we find an analytical solution of the equations and analyze their asymptotics at very high frequency. We then obtain an equation which gives radiation into each synchronous mode. We demonstrate the flexibility of the new method by calculating the frequencies and the loss factors for the lowest modes in square and round waveguides.
Mathematical Properties Relevant to Geomagnetic Field Modeling
DEFF Research Database (Denmark)
Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils
2010-01-01
Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations.The set of numerical coefficients defining this linear combination is then what one refers.......The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...... be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focussed. Time can be dealt with as an independent variable and is not explicitly considered...
Integrated field modelling[Oil and gas fields
Energy Technology Data Exchange (ETDEWEB)
Nazarian, Bamshad
2002-07-01
This research project studies the feasibility of developing and applying an integrated field simulator to simulate the production performance of an entire oil or gas field. It integrates the performance of the reservoir, the wells, the chokes, the gathering system, the surface processing facilities and whenever applicable, gas and water injection systems. The approach adopted for developing the integrated simulator is to couple existing commercial reservoir and process simulators using available linking technologies. The simulators are dynamically linked and customised into a single hybrid application that benefits from the concept of open software architecture. The integrated field simulator is linked to an optimisation routine developed based on the genetic algorithm search strategies. This enables optimisation of the system at field level, from the reservoir to the process. Modelling the wells and the gathering network is achieved by customising the process simulator. This study demonstrated that the integrated simulation improves current capabilities to simulate the performance of the entire field and optimise its design. This is achieved by evaluating design options including spread and layout of the wells and gathering system, processing alternatives, reservoir development schemes and production strategies. Effectiveness of the integrated simulator is demonstrated and tested through several field-level case studies that discuss and investigate technical problems relevant to offshore field development. The case studies cover topics such as process optimisation, optimum tie-in of satellite wells into existing process facilities, optimal well location and field layout assessment of a high pressure high temperature deepwater oil field. Case study results confirm the viability of the total field simulator by demonstrating that the field performance simulation and optimal design were obtained in an automated process with treasonable computation time. No significant
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.
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
International Nuclear Information System (INIS)
Ward, D.J.; Bondeson, A.
1994-01-01
In recent work we have shown that it is possible to completely stabilize low n, pressure-driven external modes in tokamaks by the combined effect of resistive walls and toroidal plasma rotation. We have used numerical computation to study the wall stabilization in toroidal geometry. The spectral codes MARS and NOVA have been modified to include a resistive shell in the vacuum region surrounding the plasma. Rigid toroidal rotation was modeled by making the resistive shell rotate with an externally imposed frequency ω rot while the equilibrium was static. The plasma was treated as ideally conducting and ω rot was some fraction of the sound frequency. Furthermore, the time-constant of the resistive wall, τ ω , was taken much larger than any ideal-MHD timescale. (author) 4 figs., 6 refs
A Mathematical Method for Eliminating Spin Losses in Toroidal Traction Drives
Directory of Open Access Journals (Sweden)
Qingtao Li
2015-01-01
Full Text Available The efficiency of the original Toroidal continuously variable transmission (CVT is limited due to the spin losses caused by the different speed distribution in the contact area. To overcome this drawback, this paper replaces the original working surface with a new surface derived from a differential equation and proposes a novel Logarithmic CVT. Equations and ranges of the transmission ratio range, half-cone-angle, and conformity ratio, which are essential geometrical parameters of the Logarithmic CVT, are derived. A set of geometrical parameters is further recommended. With such geometrical parameters, the transmission ratio range of the Logarithmic CVT is as wide as that of the Half-Toroidal CVT. The two types of CVTs are compared with each other in terms of efficiency based on a widely accepted computational model. The results show that efficiency of the Logarithmic CVT is higher than that of Half-Toroidal CVT except for some particular situations because of the thrust bearing losses.
Alpha heating in toroidal devices
Energy Technology Data Exchange (ETDEWEB)
Miley, G.H.
1978-01-01
Ignition (or near-ignition) by alpha heating is a key objective for the achievement of economic fusion reactors. While good confinement of high-energy alphas appears possible in larger reactors, near-term tokamak-type ignition experiments as well as some concepts for small reactors (e.g., the Field-Reversed Mirror or FRM) potentially face marginal situations. Consequently, there is a strong motivation to develop methods to evaluate alpha losses and heating profiles in some detail. Such studies for a TFTR-size tokamak and for a small FRM are described here.
Modeling and Field Results from Seismic Stimulation
International Nuclear Information System (INIS)
Majer, E.; Pride, S.; Lo, W.; Daley, T.; Nakagawa, Seiji; Sposito, Garrison; Roberts, P.
2006-01-01
Modeling the effect of seismic stimulation employing Maxwell-Boltzmann theory shows that the important component of stimulation is mechanical rather than fluid pressure effects. Modeling using Biot theory (two phases) shows that the pressure effects diffuse too quickly to be of practical significance. Field data from actual stimulation will be shown to compare to theory
Twinlike models in scalar field theories
International Nuclear Information System (INIS)
Bazeia, D.; Losano, L.; Dantas, J. D.; Gomes, A. R.; Menezes, R.
2011-01-01
This work deals with the presence of defect structures in models described by a real scalar field in a diversity of scenarios. The defect structures that we consider are static solutions of the equations of motion that depend on a single spatial dimension. We search for different models, which support the same defect solution, with the very same energy density. We work in flat spacetime, where we introduce and investigate a new class of models. We also work in curved spacetime, within the braneworld context, with a single extra dimension of infinite extent, and there we show how the brane is formed from the static field configuration.
Field based model for pedestrian dynamics
Yu, Bin; Zhang, Michael; Wang, Zhongren
2018-03-01
A pedestrian’s physical movement is simulated as a response to the pedestrian subjective evaluation of the objective environment. The objective environment is modeled by presumed fields statically or dynamically superposed. Regulation functions, which consider not only force caused by presumed fields but also local crowd densities around pedestrians, are introduced for consideration of pedestrians’ intelligence. Numerical experiments indicate that the model can be calibrated to reproduce a fundamental diagram that matches an empirical one proposed by Weidmann. Such experiments prove the model to be a useful tool for study of pedestrian dynamics.
Up-down symmetry of the turbulent transport of toroidal angular momentum in tokamaks
International Nuclear Information System (INIS)
Parra, Felix I.; Barnes, Michael; Peeters, Arthur G.
2011-01-01
Two symmetries of the local nonlinear δf gyrokinetic system of equations in tokamaks in the high flow regime are presented. The turbulent transport of toroidal angular momentum changes sign under an up-down reflection of the tokamak and a sign change of both the rotation and the rotation shear. Thus, the turbulent transport of toroidal angular momentum must vanish for up-down symmetric tokamaks in the absence of both rotation and rotation shear. This has important implications for the modeling of spontaneous rotation.
Observation of Cocurrent Toroidal Rotation in the EAST Tokamak with Lower-Hybrid Current Drive
International Nuclear Information System (INIS)
Shi Yuejiang; Xu Guosheng; Wang Fudi; Wang Mao; Fu Jia; Li Yingying; Zhang Wei; Zhang Wei; Chang Jiafeng; Lv Bo; Qian Jinping; Shan Jiafang; Liu Fukun; Ding Siye; Wan Baonian; Lee, Sang-Gon; Bitter, Manfred; Hill, Kenneth
2011-01-01
Lower-hybrid waves have been shown to induce a cocurrent change in toroidal rotation of up to 40 km/s in the L-mode plasma core region and 20 km/s in the edge of the EAST tokamak. This modification of toroidal rotation develops on different time scales. For the edge, the time scale is no more than 100 ms, but for the core the time scale is around 1 s. A simple model based on turbulent equipartition and thermoelectric pinch predicts the experimental results.
Hydrogen transport in a toroidal plasma using multigroup discrete-ordinates methodology
International Nuclear Information System (INIS)
Wienke, B.R.; Miller, W.F. Jr.; Seed, T.J.
1979-01-01
Neutral hydrogen transport in a fully ionized two-dimensional tokamak plasma was examined using discrete ordinates and contrasted with earlier analyses. In particular, curvature effects induced by toroidal geometries and ray effects caused by possible source localization were investigated. From an overview of the multigroup discrete-ordinates approximation, methodology in two-dimensional cylindrical geometry is detailed, mesh and plasma zoning procedures are sketched, and the piecewise polynomial solution algorithm on a triangular domain is obtained. Toroidal effects and comparisons as related to reaction rates and perticle spectra are examined for various model and source configurations
Spatio-Temporal Modeling of Neuron Fields
DEFF Research Database (Denmark)
Lund, Adam
The starting point and focal point for this thesis was stochastic dynamical modelling of neuronal imaging data with the declared objective of drawing inference, within this model framework, in a large-scale (high-dimensional) data setting. Implicitly this objective entails carrying out three......-temporal array data. This framework was developed with neuron field models in mind but may in turn be applied to other settings conforming to the spatio-temporal array data setup....
Elastic stability and vibration of toroidal magnets for fusion reactors. Final report
International Nuclear Information System (INIS)
Moon, F.C.; Swanson, C.
1975-09-01
The vibration and elastic stability of a set of discrete superconducting toroidal field magnets arranged to form a ''bumpy'' torus is examined. The mutual destabilizing magnetic forces between magnet pairs are calculated using a numerical differential inductance technique. It is shown that the mutual attractive magnetic forces can produce elastic buckling of the entire toroidal set. The vibration modes of the set are also found as functions of the coil current. The response of the set of magnets to an earthquake type motion of the toroidal base is calculated. The calculations have been incorporated in a computer code which accompanies the report. Measurements are made of the lateral stiffness of a flexible, planar, superconducting coil between two rigid coils in series. These tests show a dramatic decrease in the natural bending frequency with subsequent elastic instability or ''buckling'' at a critical value of the current in the coils. These observations support a magnetoelastic analysis which shows that proposed designs, of toroidal field coils for Tokamak fusion reactors, have insufficient lateral support for mechanical stability of the magnets
Field modeling for transcranial magnetic stimulation
DEFF Research Database (Denmark)
Thielscher, Axel; Antunes, Andre; Saturnino, Guilherme B
2015-01-01
) improving the usability of the tools for field calculation to the level that they can be easily used by non-experts. We then introduce a new version of our pipeline for field calculations (www.simnibs.org) that substantially simplifies setting up and running TMS and tDCS simulations based on Finite......Electric field calculations based on numerical methods and increasingly realistic head models are more and more used in research on Transcranial Magnetic Stimulation (TMS). However, they are still far from being established as standard tools for the planning and analysis in practical applications...... of TMS. Here, we start by delineating three main challenges that need to be addressed to unravel their full potential. This comprises (i) identifying and dealing with the model uncertainties, (ii) establishing a clear link between the induced fields and the physiological stimulation effects, and (iii...
A Hamiltonian Five-Field Gyrofluid Model
Keramidas Charidakos, Ioannis; Waelbroeck, Francois; Morrison, Philip
2015-11-01
Reduced fluid models constitute versatile tools for the study of multi-scale phenomena. Examples include magnetic islands, edge localized modes, resonant magnetic perturbations, and fishbone and Alfven modes. Gyrofluid models improve over Braginskii-type models by accounting for the nonlocal response due to particle orbits. A desirable property for all models is that they not only have a conserved energy, but also that they be Hamiltonian in the ideal limit. Here, a Lie-Poisson bracket is presented for a five-field gyrofluid model, thereby showing the model to be Hamiltonian. The model includes the effects of magnetic field curvature and describes the evolution of electron and ion densities, the parallel component of ion and electron velocities and ion temperature. Quasineutrality and Ampere's law determine respectively the electrostatic potential and magnetic flux. The Casimir invariants are presented, and shown to be associated to five Lagrangian invariants advected by distinct velocity fields. A linear, local study of the model is conducted both with and without Landau and diamagnetic resonant damping terms. Stability criteria and dispersion relations for the electrostatic and the electromagnetic cases are derived and compared with their analogs for fluid and kinetic models. This work was funded by U.S. DOE Contract No. DE-FG02-04ER-54742.
Tobias, B. J.
2015-11-01
The dynamic, nonlinear evolution of tearing instabilities on DIII-D reveals a coupling of rational surfaces that can lead to phase-locking amongst multiple rotating magnetic island chains. This loss of flow shear increases disruptivity, particularly at the low level of rotation expected in ITER. Bifurcation of differential mode frequency and fluid rotation in hybrid scenario discharges has been interpreted by comparison to a recently developed theory of nonlinear mode coupling. Magnetic islands of different toroidal mode number couple to flatten the toroidal rotation profile, and the resulting phase-locked state is similar to the so-called ``slinky'' mode observed in reversed field pinch devices. Reduction of the edge safety factor increases the momentum transport, easily overwhelming the local torque density available from neutral beam injection. In discharges with q95 ~ 4.5, however, the participating modes do not remain phase-locked. In these cases, ECE-Imaging data have been used to show that the poloidal rotation of the composite, multi-helicity structure exceeds that of the measured carbon (and estimated deuterium) fluid flow. The present model of nonlinear 3-wave mode coupling does not generate the forces required to drive this rotation. Therefore, flow shear inversion represents a transition from phase-locking to a new regime of convective momentum transport in which additional mechanisms become important. These results highlight the importance of controlling multi-mode interactions in order to maintain stabilizing flow shear. Supported by US DOE DE-AC02-09CH11466, DE-FC02-04ER54698, DE-FG02-07ER54917, DE-FG02-92-ER54141.
Calculation of coherent synchrotron radiation in toroidal waveguides by paraxial wave equation
Directory of Open Access Journals (Sweden)
D. R. Gillingham
2007-05-01
Full Text Available A new technique for the simulation of coherent synchrotron radiation (CSR and space-charge fields from a single electron bunch in straight or toroidal rectangular waveguide sections has been developed. It is based on the integration of the paraxial approximation to the wave equations, using the perturbation technique where the bending radius is large compared to the dimension of the waveguide. We have implemented an unconditionally stable integration method in the time domain with transparent boundary conditions that allows the use of a minimally sized computational domain about the bunch. This technique explicitly enforces the causality condition so that no portion of the fields can propagate faster than the speed of light, can be used with arbitrary three-dimensional charge distributions, and contains corrections for finite energy. We have also developed a method for the calculation of the transverse forces within the bunch including space-charge. This method has been developed for incorporation with a particle-in-cell code so that we may self-consistently model CSR and space-charge in combinations of bending sections with a fully dynamic electron bunch in an efficient manner. In this paper we describe the model and methods for calculation of the fields in detail and compare results to theory wherever possible.
The CHAOS-4 Geomagnetic Field Model
DEFF Research Database (Denmark)
Olsen, Nils; Finlay, Chris; Lühr, H.
We present CHAOS-4, a new version in the CHAOS model series, which aims at describing the Earth's magnetic field with high spatial resolution (terms up to spherical degree n=90 for the crustal field, and up to n=16 for the time-varying core field are robustly determined) and high temporal...... (with expansions in the GSM and SM coordinate system up to degree n = 2 and parameterization of the time dependence using the decomposition of Dst into external (Est) and induced (Ist) parts) and perform an in-flight alignment of the vector data (co-estimation of the Euler describing the rotation...
Reversed-Field Pinch plasma model
International Nuclear Information System (INIS)
Miley, G.H.; Nebel, R.A.; Moses, R.W.
1979-01-01
The stability of a Reversed-Field Pinch (RFP) is strongly dependent on the plasma profile and the confining sheared magnetic field. Magnetic diffusion and thermal transport produce changing conditions of stability. Despite the limited understanding of RFP transport, modelling is important to predict general trends and to study possible field programming options. To study the ZT-40 experiment and to predict the performance of future RFP reactors, a one-dimensional transport code has been developed. This code includes a linear, ideal MHD stability check based on an energy principle. The transport section integrates plasma profiles forward in time while the stability section periodically checks the stability of the evolving plasma profile
An integral equation-based numerical solver for Taylor states in toroidal geometries
O'Neil, Michael; Cerfon, Antoine J.
2018-04-01
We present an algorithm for the numerical calculation of Taylor states in toroidal and toroidal-shell geometries using an analytical framework developed for the solution to the time-harmonic Maxwell equations. Taylor states are a special case of what are known as Beltrami fields, or linear force-free fields. The scheme of this work relies on the generalized Debye source representation of Maxwell fields and an integral representation of Beltrami fields which immediately yields a well-conditioned second-kind integral equation. This integral equation has a unique solution whenever the Beltrami parameter λ is not a member of a discrete, countable set of resonances which physically correspond to spontaneous symmetry breaking. Several numerical examples relevant to magnetohydrodynamic equilibria calculations are provided. Lastly, our approach easily generalizes to arbitrary geometries, both bounded and unbounded, and of varying genus.
Bai, Xue; Liu, Yueqiang; Gao, Zhe
2017-10-01
Plasma response to the resonant magnetic perturbation (RMP) field is numerically investigated by an extended toroidal fluid model, which includes anisotropic thermal transport physics parallel and perpendicular to the total magnetic field. The thermal transport is found to be effective in eliminating the toroidal average curvature induced plasma screening (the so called Glasser-Green-Johnson, GGJ screening) in a slow toroidal flow regime, whilst having minor effect on modifying the conventional plasma screening regimes at faster flow. This physics effect of interaction between thermal transport and GGJ screening is attributed to the modification of the radial structure of the shielding current, which resulted from the plasma response to the applied field. The modification of the plasma response (shielding current, response field, plasma displacement, and the perturbed velocity) also has direct consequence on the toroidal torques produced by RMP. Modelling results show that thermal transport reduces the resonant electromagnetic torque as well as the torque associated with the Reynolds stress, but enhances the neoclassical toroidal viscous torque at slow plasma flow.
Modeling emotional dynamics : currency versus field.
Energy Technology Data Exchange (ETDEWEB)
Sallach, D .L.; Decision and Information Sciences; Univ. of Chicago
2008-08-01
Randall Collins has introduced a simplified model of emotional dynamics in which emotional energy, heightened and focused by interaction rituals, serves as a common denominator for social exchange: a generic form of currency, except that it is active in a far broader range of social transactions. While the scope of this theory is attractive, the specifics of the model remain unconvincing. After a critical assessment of the currency theory of emotion, a field model of emotion is introduced that adds expressiveness by locating emotional valence within its cognitive context, thereby creating an integrated orientation field. The result is a model which claims less in the way of motivational specificity, but is more satisfactory in modeling the dynamic interaction between cognitive and emotional orientations at both individual and social levels.
Mean-field models and superheavy elements
International Nuclear Information System (INIS)
Reinhard, P.G.; Bender, M.; Maruhn, J.A.; Frankfurt Univ.
2001-03-01
We discuss the performance of two widely used nuclear mean-field models, the relativistic mean-field theory (RMF) and the non-relativistic Skyrme-Hartree-Fock approach (SHF), with particular emphasis on the description of superheavy elements (SHE). We provide a short introduction to the SHF and RMF, the relations between these two approaches and the relations to other nuclear structure models, briefly review the basic properties with respect to normal nuclear observables, and finally present and discuss recent results on the binding properties of SHE computed with a broad selection of SHF and RMF parametrisations. (orig.)
Optimizing dc-resistance of a foil wounded toroidal inductor combining matlab and comsol
DEFF Research Database (Denmark)
Schneider, Henrik; Andersen, Thomas; Knott, Arnold
2013-01-01
An optimization routine is presented to optimize the shape of a foil winding of a toroid inductor in terms of the DC resistance. MATLAB was used to define the geometry of the foil winding and COMSOL was used to import the geometry and create a 3D finite element model. The initial parameters...
Analysis and correction of intrinsic non-axisymmetric magnetic fields in high-β DIII-D plasmas
International Nuclear Information System (INIS)
Garofalo, A.M.; La Haye, R.J.; Scoville, J.T.
2002-01-01
Rapid plasma toroidal rotation, sufficient for stabilization of the n=1 resistive wall mode, can be sustained by improving the axisymmetry of the toroidal magnetic field geometry of DIII-D. The required symmetrization is determined experimentally both by optimizing currents in external n=1 correction coils with respect to the plasma rotation, and by use of the n=1 magnetic feedback to detect and minimize the plasma response to non-axisymmetric fields as β increases. Both methods point to an intrinsic ∼7 G (0.03% of the toroidal field), m/n=2/1 resonant helical field at the q=2 surface as the cause of the plasma rotation slowdown above the no-wall β limit. The drag exerted by this field on the plasma rotation is consistent with the behaviour of 'slipping' in a simple induction motor model. (author)
Preliminary Phase Field Computational Model Development
Energy Technology Data Exchange (ETDEWEB)
Li, Yulan [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xu, Ke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Suter, Jonathan D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McCloy, John S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Bradley R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ramuhalli, Pradeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2014-12-15
This interim report presents progress towards the development of meso-scale models of magnetic behavior that incorporate microstructural information. Modeling magnetic signatures in irradiated materials with complex microstructures (such as structural steels) is a significant challenge. The complexity is addressed incrementally, using the monocrystalline Fe (i.e., ferrite) film as model systems to develop and validate initial models, followed by polycrystalline Fe films, and by more complicated and representative alloys. In addition, the modeling incrementally addresses inclusion of other major phases (e.g., martensite, austenite), minor magnetic phases (e.g., carbides, FeCr precipitates), and minor nonmagnetic phases (e.g., Cu precipitates, voids). The focus of the magnetic modeling is on phase-field models. The models are based on the numerical solution to the Landau-Lifshitz-Gilbert equation. From the computational standpoint, phase-field modeling allows the simulation of large enough systems that relevant defect structures and their effects on functional properties like magnetism can be simulated. To date, two phase-field models have been generated in support of this work. First, a bulk iron model with periodic boundary conditions was generated as a proof-of-concept to investigate major loop effects of single versus polycrystalline bulk iron and effects of single non-magnetic defects. More recently, to support the experimental program herein using iron thin films, a new model was generated that uses finite boundary conditions representing surfaces and edges. This model has provided key insights into the domain structures observed in magnetic force microscopy (MFM) measurements. Simulation results for single crystal thin-film iron indicate the feasibility of the model for determining magnetic domain wall thickness and mobility in an externally applied field. Because the phase-field model dimensions are limited relative to the size of most specimens used in
Radial diffusion of toroidally trapped particles induced by lower hybrid and fast waves
International Nuclear Information System (INIS)
Krlin, L.
1992-10-01
The interaction of RF field with toroidally trapped particles (bananas) can cause their intrinsic stochastically diffusion both in the configuration and velocity space. In RF heating and/or current drive regimes, RF field can interact with plasma particles and with thermonuclear alpha particles. The aim of this contribution is to give some analytical estimates of induced radial diffusion of alphas and of ions. (author)
Quercia, A.; Albanese, R.; Fresa, R.; Minucci, S.; Arshad, S.; Vayakis, G.
2017-12-01
The paper carries out a comprehensive study of the performances of Rogowski coils. It describes methodologies that were developed in order to assess the capabilities of the Continuous External Rogowski (CER), which measures the total toroidal current in the ITER machine. Even though the paper mainly considers the CER, the contents are general and relevant to any Rogowski sensor. The CER consists of two concentric helical coils which are wound along a complex closed path. Modelling and computational activities were performed to quantify the measurement errors, taking detailed account of the ITER environment. The geometrical complexity of the sensor is accurately accounted for and the standard model which provides the classical expression to compute the flux linkage of Rogowski sensors is quantitatively validated. Then, in order to take into account the non-ideality of the winding, a generalized expression, formally analogue to the classical one, is presented. Models to determine the worst case and the statistical measurement accuracies are hence provided. The following sources of error are considered: effect of the joints, disturbances due to external sources of field (the currents flowing in the poloidal field coils and the ferromagnetic inserts of ITER), deviations from ideal geometry, toroidal field variations, calibration, noise and integration drift. The proposed methods are applied to the measurement error of the CER, in particular in its high and low operating ranges, as prescribed by the ITER system design description documents, and during transients, which highlight the large time constant related to the shielding of the vacuum vessel. The analyses presented in the paper show that the design of the CER diagnostic is capable of achieving the requisite performance as needed for the operation of the ITER machine.
Toroidal magnetic detector for high resolution measurement of muon momenta
Bonanos, Peter
1992-01-01
A muon detector system including central and end air-core superconducting toroids and muon detectors enclosing a central calorimeter/detector. Muon detectors are positioned outside of toroids and all muon trajectory measurements are made in a nonmagnetic environment. Internal support for each magnet structure is provided by sheets, located at frequent and regularly spaced azimuthal planes, which interconnect the structural walls of the toroidal magnets. In a preferred embodiment, the shape of the toroidal magnet volume is adjusted to provide constant resolution over a wide range of rapidity.
MHD Stability of Free Boundary Toroidal Z Pinch
Sugisaki, Kiwamu
1990-06-01
The Magnetohydrodynamic (MHD) stability of a free boundary toroidal Z pinch plasma is investigated. Equilibrium field profiles are chosen so that μ is nearly uniform in the central region, μ and dμ/dr vanish on the boundary and Suydam’s criterion is satisfied throughout the plasma. The stability of the equilibrium is examined for the ratio b of the conducting wall radius to the plasma radius and plasma pressure. The stability of non-resonant ideal modes is determined mainly from the safty factor on the axis. Non-resonant modes are dominant for low plasma pressure, whereas resonant modes are dominant for high plasma pressure. Tearing modes are stable only for b below 1.04. The width of the magnetic islands produced from the tearing modes is evaluated. As b increases, overlap of the magnetic islands occurs over a wide area in the plasma.
Staircase Models from Affine Toda Field Theory
Dorey, P; Dorey, Patrick; Ravanini, Francesco
1993-01-01
We propose a class of purely elastic scattering theories generalising the staircase model of Al. B. Zamolodchikov, based on the affine Toda field theories for simply-laced Lie algebras g=A,D,E at suitable complex values of their coupling constants. Considering their Thermodynamic Bethe Ansatz equations, we give analytic arguments in support of a conjectured renormalisation group flow visiting the neighbourhood of each W_g minimal model in turn.
A field theoretic model for static friction
Mahyaeh, I.; Rouhani, S.
2013-01-01
We present a field theoretic model for friction, where the friction coefficient between two surfaces may be calculated based on elastic properties of the surfaces. We assume that the geometry of contact surface is not unusual. We verify Amonton's laws to hold that friction force is proportional to the normal load.This model gives the opportunity to calculate the static coefficient of friction for a few cases, and show that it is in agreement with observed values. Furthermore we show that the ...
Improved modeling techniques for turbomachinery flow fields
Energy Technology Data Exchange (ETDEWEB)
Lakshminarayana, B.; Fagan, J.R. Jr.
1995-12-31
This program has the objective of developing an improved methodology for modeling turbomachinery flow fields, including the prediction of losses and efficiency. Specifically, the program addresses the treatment of the mixing stress tensor terms attributed to deterministic flow field mechanisms required in steady-state Computational Fluid Dynamic (CFD) models for turbomachinery flow fields. These mixing stress tensors arise due to spatial and temporal fluctuations (in an absolute frame of reference) caused by rotor-stator interaction due to various blade rows and by blade-to-blade variation of flow properties. This will be accomplished in a cooperative program by Penn State University and the Allison Engine Company. These tasks include the acquisition of previously unavailable experimental data in a high-speed turbomachinery environment, the use of advanced techniques to analyze the data, and the development of a methodology to treat the deterministic component of the mixing stress tenor.
Mathematical Properties Relevant to Geomagnetic Field Modeling
DEFF Research Database (Denmark)
Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils
2014-01-01
Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations. The set of numerical coefficients defining this linear combination is then what one refers to as a geomag...
An analysis of plasma ion toroidal rotation during large amplitude MHD activity in JET
International Nuclear Information System (INIS)
Snipes, J.A.; Esch, H.P.L. de; Lazzaro, E.; Stork, D.; Hellermann, M. von; Galvao, R.; Hender, T.C.; Zasche, D.
1989-01-01
A detailed study of plasma ion toroidal rotation in JET during large amplitude MHD activity has revealed a strong viscous force that couples plasma ions to MHD modes. Depending on the MHD modes present, this force can couple across all of the plasma cross section, across only the central region, roughly within the q=1 surface, or across only the outer region outside the q=1.5 surface. The force acts to flatten the ion toroidal rotation frequency profile, measured by the JET active charge exchange spectroscopy diagnostic, across the coupled region of plasma. The frequency of rotation in this region agrees with the MHD oscillation frequency measured by magnetic pick-up coils at the wall. The strength of the force between the ions and modes becomes evident during high power NBI when the mode locks and drags the ion toroidal rotation frequency to zero, within the errors of the measurements. The present theories of plasma rotation either ignore MHD effects entirely, consider only moderate n toroidal field ripple, or low n ripple effects. (author) 7 refs., 3 figs
Non-Solenoidal Startup Research Directions on the Pegasus Toroidal Experiment
Fonck, R. J.; Bongard, M. W.; Lewicki, B. T.; Reusch, J. A.; Winz, G. R.
2017-10-01
The Pegasus research program has been focused on developing a physical understanding and predictive models for non-solenoidal tokamak plasma startup using Local Helicity Injection (LHI). LHI employs strong localized electron currents injected along magnetic field lines in the plasma edge that relax through magnetic turbulence to form a tokamak-like plasma. Pending approval, the Pegasus program will address a broader, more comprehensive examination of non-solenoidal tokamak startup techniques. New capabilities may include: increasing the toroidal field to 0.6 T to support critical scaling tests to near-NSTX-U field levels; deploying internal plasma diagnostics; installing a coaxial helicity injection (CHI) capability in the upper divertor region; and deploying a modest (200-400 kW) electron cyclotron RF capability. These efforts will address scaling of relevant physics to higher BT, separate and comparative studies of helicity injection techniques, efficiency of handoff to consequent current sustainment techniques, and the use of ECH to synergistically improve the target plasma for consequent bootstrap and neutral beam current drive sustainment. This has an ultimate goal of validating techniques to produce a 1 MA target plasma in NSTX-U and beyond. Work supported by US DOE Grant DE-FG02-96ER54375.
Electron heat diffusivity in radially-bounded ergodic region of toroidal plasma
Kanno, Ryutaro; Nunami, Masanori; Satake, Shinsuke; Matsuoka, Seikichi; Takamaru, Hisanori
2018-01-01
Drift-kinetic δ f simulations are performed to investigate effect of ergodic field lines caused by resonant magnetic perturbations (RMPs) on radial heat diffusivity of electrons in the edge region of toroidal plasma of collisionality ν_\\ast ∼ 0.1 . The following is assumed in the simulations. The ergodic region is bounded radially on both sides by closed magnetic surfaces. The pressure gradient remains nonzero in the ergodic region because of an incomplete flattening of the pressure profile, and the characteristic scale length of the pressure gradient is of larger order than the overlapping width of the neighbouring magnetic islands. It is found in the quasi-steady state of δ f that the electron heat diffusivity is of smaller order than the theoretical estimate derived by the Rechester–Rosenbluth model (Rechester and Rosenbluth 1978 Phys. Rev. Lett. 40 38). The radial heat conduction is dominated not only by parallel motions along the ergodic field lines, but also by trapped particle motions generated by the RMP field. The contribution of the trapped particles reduces the radial heat conduction enhanced by the parallel motions.
McCarthy, N. M.; Jorgensen, A. M.; Stone, W. D.; Zesta, E.
2010-12-01
Equatorial plasma mass density in the Inner Magnetosphere of the Earth has been traditionally derived from measurements of Field Line Resonances from pairs of ground magnetometers closely spaced in latitude. The full plasma mass density along the flux tube can be determined using such measurements in an inversion of the Field Line Resonance Equation. Cummings et al [1969] developed the Field Line Resonance equation and numerically solved for the Field Line Resonances by assuming a power law distribution that varied with the geocentric distance from the equatorial crossing point of the field lines and a dipole model for the Earth's magnetic field. So far all numerical solutions of the Field Line Resonance Equation use some form of a power law distribution of the mass density along the field line, that depends on the magnetic field model, typically assumed to be a dipole, with only one recent work exploring deviations from a dipole magnetic field. Another fundamental assumption in the solution of the Field Line Resonance Equation is that of perfectly conducting, flat ionospheres as the two boundaries of the field line. While this assumption is considered valid for L values greater than 2, recent works have found it to be invalid for L values of 3 or less. In the present paper we solve the Field Line Resonance Equation for L values less than 3.5 using a three dimensional ionosphere, and without assuming a power law for the mass density distribution along the field line. Instead we use plasma mass density data from the Field Line Interhemispheric Plasma (FLIP) model to numerically solve the Field Line Resonance Equation for the eigenfrequencies. We also examine how the resonance frequencies vary as a function of the driving parameters. Finally we examine two events in which we compare the derived frequencies with measurements from the SAMBA magnetometer array.
Kuroda, Kengoh; Wada, Manato; Uchida, Masaki; Tanaka, Hitoshi; Maekawa, Takashi
2016-02-01
In toroidal electron cyclotron resonance (ECR) plasmas under a weak external vertical field {{B}\\text{V}} a part of the pressure driven vertical charge separation current returns along the helical field lines, generating a toroidal current. The rest circulates via the conducting vacuum vessel. Only the toroidal current contributes to the production of a closed flux surface. Both the toroidal and vertical currents are an equilibrium current that provides a radial force by the interaction with the vertical field and the toroidal field, respectively, to counter-balance the outward pressure ballooning force. We have done experiments using 2.45 GHz microwaves in the low aspect ratio torus experiment (LATE) device to investigate in what way and how much the toroidal current is generated towards the initiation of a closed flux surface. In steady discharges by {{P}\\text{inj}}=1.5 kW under various {{B}\\text{V}} both the pressure and the toroidal current become large with {{B}\\text{V}} . When {{B}\\text{V}}=6.8 G, a toroidal current of 290 A is generated and the vertical field is reduced to 1.2 G inside the current channel, being close to the initiation of a closed flux surface. In this plasma the return current does not obey Ohm’s law. Instead, the return current flows so that the electric force on the electron fluid is balanced with the pressure gradient along the field lines. Near the top and bottom boundaries superthermal electrons flow beyond the potential barrier onto the walls along the field lines. In another discharge by the low power of {{P}\\text{inj}}=1.0 kW under {{B}\\text{V}}=8.3 G, both the toroidal current and the pressure steadily increase for an initial duration of 1.1 s and then abruptly jump, generating an initial closed flux surface. While the counter force from the vertical current is initially dominant, that from the toroidal current gradually increases and becomes four times larger than that from the vertical current just before the initiation
Effective field theory and the quark model
International Nuclear Information System (INIS)
Durand, Loyal; Ha, Phuoc; Jaczko, Gregory
2001-01-01
We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the 'nonrelativistic' constituent QM for baryon masses and moments is completely equivalent through O(m s ) to a parametrization of the relativistic field theory in a general spin-flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections
Dynamical Field Model of Hand Preference
Franceschetti, Donald R.; Cantalupo, Claudio
2000-11-01
Dynamical field models of information processing in the nervous system are being developed by a number of groups of psychologists and physicists working together to explain The details of behaviors exhibited by a number of animal species. Here we adapt such a model to the expression of hand preference in a small primate, the bushbaby (Otolemur garnetti) . The model provides a theoretical foundation for the interpretation of an experiment currently underway in which a several of these animals are forced to extend either right or left hand to retrieve a food item from a rotating turntable.
Studies on Plasmoid Merging using Compact Toroid Injectors
Allfrey, Ian; Matsumoto, Tadafumi; Roche, Thomas; Gota, Hiroshi; Edo, Takahiro; Asai, Tomohiko; Sheftman, Daniel; Osin Team; Dima Team
2017-10-01
C-2 and C-2U experiments have used magnetized coaxial plasma guns (MCPG) to inject compact toroids (CTs) for refueling the long-lived advanced beam-driven field-reversed configuration (FRC) plasma. This refueling method will also be used for the C-2W experiment. To minimize momentum transfer from the CT to the FRC two CTs are injected radially, diametrically opposed and coincident in time. To improve understanding of the CT characteristics TAE has a dedicated test bed for the development of CT injectors (CTI), where plasmoid merging experiments are performed. The test bed has two CTIs on axis with both axial and transverse magnetic fields. The 1 kG magnetic fields, intended to approximate the magnetic field strength and injection angle on C-2W, allow studies of cross-field transport and merging. Both CTIs are capable of injecting multiple CTs at up to 1 kHz. The resulting merged CT lives >100 μs with a radius of 25 cm. More detailed results of CT parameters will be presented.
Anderson, J. E.
1974-01-01
An experimental program was conducted for the purpose of evaluating propellant behavior characteristics in spinning toroidal tanks. The effects of typical mission requirements, and related phenomena upon propellant slosh and settling, and orientation and stability of the ullage were investigated in a subscale model tank under both one-g and low-g acceleration environments. Specific conditions included were axial acceleration, spin rate, spinrate change, and spacecraft wobble, both singly and in combination. Methanol and water in combination with appropriate spin-rates and accelerations of the scale model system were used to simulate the behavior of fluorine, nitrogen tetroxide, monomethylhydrazine, and hydrazine. The experimental results indicate that no major fluid behavior problems would be encountered with the use of toroidal tanks containing any of the four propellants in a proposed spin-stabilized orbiter spacecraft.
Modeling quantization effects in field effect transistors
Troger, C
2001-01-01
Numerical simulation in the field of semiconductor device development advanced to a valuable, cost-effective and flexible facility. The most widely used simulators are based on classical models, as they need to satisfy time and memory constraints. To improve the performance of field effect transistors such as MOSFETs and HEMTs these devices are continuously scaled down in their dimensions. Consequently the characteristics of such devices are getting more and more determined by quantum mechanical effects arising from strong transversal fields in the channel. In this work an approach based on a two-dimensional electron gas is used to describe the confinement of the carriers. Quantization is considered in one direction only. For the derivation of a one-dimensional Schroedinger equation in the effective mass framework a non-parabolic correction for the energy dispersion due to Kane is included. For each subband a non-parabolic dispersion relation characterized by subband masses and subband non-parabolicity coeffi...
Models of large-scale magnetic fields in stellar interiors. Application to solar and ap stars
International Nuclear Information System (INIS)
Duez, Vincent
2009-01-01
Stellar astrophysics needs today new models of large-scale magnetic fields, which are observed through spectropolarimetry at the surface of Ap/Bp stars, and thought to be an explanation for the uniform rotation of the solar radiation zone, deduced from helio seismic inversions. During my PhD, I focused on describing the possible magnetic equilibria in stellar interiors. The found configurations are mixed poloidal-toroidal, and minimize the energy for a given helicity, in analogy with Taylor states encountered in spheromaks. Taking into account the self-gravity leads us to the 'non force-free' equilibria family, that will thus influence the stellar structure. I derived all the physical quantities associated with the magnetic field; then I evaluated the perturbations they induce on gravity, thermodynamic quantities as well as energetic ones, for a solar model and an Ap star. 3D MHD simulations allowed me to show that these equilibria form a first stable states family, the generalization of such states remaining an open question. It has been shown that a large-scale magnetic field confined in the solar radiation zone can induce an oblateness comparable to a high core rotation law. I also studied the secular interaction between the magnetic field, the differential rotation and the meridional circulation in the aim of implementing their effects in a next generation stellar evolution code. The influence of the magnetism on convection has also been studied. Finally, hydrodynamic processes responsible for the mixing have been compared with diffusion and a change of convection's efficiency in the case of a CoRoT star target. (author) [fr
High-performance phase-field modeling
Vignal, Philippe
2015-04-27
Many processes in engineering and sciences involve the evolution of interfaces. Among the mathematical frameworks developed to model these types of problems, the phase-field method has emerged as a possible solution. Phase-fields nonetheless lead to complex nonlinear, high-order partial differential equations, whose solution poses mathematical and computational challenges. Guaranteeing some of the physical properties of the equations has lead to the development of efficient algorithms and discretizations capable of recovering said properties by construction [2, 5]. This work builds-up on these ideas, and proposes novel discretization strategies that guarantee numerical energy dissipation for both conserved and non-conserved phase-field models. The temporal discretization is based on a novel method which relies on Taylor series and ensures strong energy stability. It is second-order accurate, and can also be rendered linear to speed-up the solution process [4]. The spatial discretization relies on Isogeometric Analysis, a finite element method that possesses the k-refinement technology and enables the generation of high-order, high-continuity basis functions. These basis functions are well suited to handle the high-order operators present in phase-field models. Two-dimensional and three dimensional results of the Allen-Cahn, Cahn-Hilliard, Swift-Hohenberg and phase-field crystal equation will be presented, which corroborate the theoretical findings, and illustrate the robustness of the method. Results related to more challenging examples, namely the Navier-Stokes Cahn-Hilliard and a diusion-reaction Cahn-Hilliard system, will also be presented. The implementation was done in PetIGA and PetIGA-MF, high-performance Isogeometric Analysis frameworks [1, 3], designed to handle non-linear, time-dependent problems.
Parametric design studies of toroidal magnetic energy storage units
International Nuclear Information System (INIS)
Herring, J.S.
1990-01-01
Superconducting magnetic energy storage (SMES) units have a number of advantages as storage devices. Electrical current is the input, output and stored medium, allowing for completely solid-state energy conversion. The magnets themselves have no moving parts. The round-trip efficiency is higher than those for batteries, compressed air or pumped hydro. Output power can be very high, allowing complete discharge of the unit within a few seconds. Finally, the unit can be designed for a very large number of cycles, limited basically by fatigue in the structural components. A small systems code has been written to produce and evaluate self-consistent designs for toroidal superconducting energy storage units. The units can use either low temperature or high temperature superconductors. The coils have 'D' shape where the conductor and its stabilizer/structure is loaded only in tension and the centering forces are borne by a bucking cylinder. The coils are convectively cooled from a cryogenic reservoir in the bore of the coils. The coils are suspended in a cylindrical metal shell which protects the magnet during rail, automotive or shipboard use. It is important to note that the storage unit does not rely on its surroundings for structural support, other than normal gravity and inertial loads. This paper presents designs for toroidal energy storage units produced by the systems code. A wide range of several parameters have been considered, resulting in units storing from 1 MJ to 72 GJ. Maximum fields range from 5 t to 20 T. The masses and volumes of the coils, bucking cylinder, coolant, insulation and outer shell are calculated. For unattended use, the allowable operating time using only the boiloff of the cryogenic fluid for refrigeration is calculated. For larger units, the coils have been divided into modules suitable for normal truck or rail transport. 8 refs., 5 tabs
Toroidally asymmetric particle transport caused by phase-locking of MHD modes in RFX-mod
International Nuclear Information System (INIS)
Lorenzini, R.; Terranova, D.; Auriemma, F.; Cavazzana, R.; Innocente, P.; Martini, S.; Serianni, G.; Zuin, M.
2007-01-01
The particle and energy transport in reversed field pinch experiments is affected by the locking in phase of the tearing modes, also dubbed dynamo modes, that sustain the magnetic configuration. In standard RFP pulses many m = 1 and m = 0 resonant modes have a relatively large amplitude (a spectrum dubbed MH for multiple helicity). The locking in phase of m = 1 tearing modes produces a helical deformation (locked mode (LM)) of the magnetic surfaces in a region of approximately 40 toroidal degrees. The region of the LM is characterized by a strong plasma-wall interaction and by high losses of energy and particles that account for a significant fraction of the input power and of the total particle outflux. The locking in phase of m = 0 modes modifies the plasma radius, shrinking and enlarging the plasma cross section in two wide toroidal regions of about 100 0 . The purpose of this paper is to investigate to what extent the locking in phase of m = 0 modes introduces toroidal asymmetries in the transport properties of the plasma. This study has been carried out investigating the shape of the density profile in the RFX-mod experiment. The analyses show that the profile exhibits a dependence on the toroidal angle, which is related to the deformation of the plasma column due to the locking in phase of m = 0 modes: the least steep density gradients at the edge are found in the region where the plasma column is shrunk, entailing that in this region the particle transport is enhanced. An analogous asymmetry also characterizes the density and magnetic fluctuations at the edge, which are enhanced in the same toroidal region where the particle transport also is enhanced. This result can be considered the first experimental evidence of an instability localized where the plasma column is shrunk
Design study of superconducting toroidal magnet for tokamak experimental fusion reactor
International Nuclear Information System (INIS)
1977-10-01
Design study of the superconducting toroidal magnet for the Tokamak experimental fusion reactor has been carried out. Performed here were conductor design, magnetic field calculation, design of coil support, stress analysis, design of refrigeration system and safety analysis. The maximum toroidal field at the coil is 12.0 T, providing 6.0 T at the plasma center. The coil bore is 7.3 x 11.2 m, and the coil shape is deformed constant-tension D-shape. 16 coil design was chosen, considering the necessity for good access for the evacuation port or the support structure of blanket and shield. The maximum field ripple obtained in the plasma region is 0.47%. The operational current is 25,100 amperes, and the cryogenic stabilization is fulfilled. Nb 3 Sn superconductor was chosen in spite of its brittleness, to attain a toroidal field of 12 T which is higher than a practical limit for NbTi superconductor. The development of large Nb 3 Sn coil technology would be necessary to realize an economic fusion power reactor. (auth.)
Characteristics of toroidal energy deposition asymmetries in ASDEX
International Nuclear Information System (INIS)
Evans, T.E.; Neuhauser, J.; Leuterer, F.; Mueller, E.R.
1990-01-01
Large toroidal and poloidal asymmetries with characteristics which are sensitively dependent on q a , the vertical position of the plasma, and the type of additional heating are observed in the energy flow to the ASDEX divertor target plates. The largest asymmetries and total energy depositions are observed during lower hybrid wave injection experiments with approximately 50% of the input energy going to the combined divertor targets and shields. A maximum localized energy density loading of 10 MJ/m 2 is typical under these conditions. Measurements of the asymmetries are consistent with a model in which magnetic islands and ergodicity due to intrinsic magnetic perturbations dominate the energy transpot across the primary magnetic separatrix. The results emphasize the essential role of resonant magnetic perturbations in determining the performance of tokamaks and demonstrate that non-axisymmetric effects caused by small perturbations become increasingly important in determining the transport properties as the injected power is increased. (orig.)
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 | plasma current for heating and 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 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.
Interaction of supra-thermal ions with turbulence in a magnetized toroidal plasma
International Nuclear Information System (INIS)
Plyushchev, G.
2009-01-01
This thesis addresses the interaction of a supra-thermal ion beam with turbulence in the simple magnetized toroidal plasma of TORPEX. The first part of the Thesis deals with the ohmic assisted discharges on TORPEX. The aim of these discharges is the investigation of the open to closed magnetic field line transition. The relevant magnetic diagnostics were developed. Ohmic assisted discharges with a maximum plasma current up to 1 kA are routinely obtained. The equilibrium conditions on the vacuum magnetic field configuration were investigated. In the second part of the Thesis, the design of the fast ion source and detector are discussed. The accelerating electric field needed for the fast ion source was optimized. The fast ion source was constructed and commissioned. To detect the fast ions a specially designed gridded energy analyzer was used. The electron energy distribution function was obtained to demonstrate the efficiency of the detector. The experiments with the fast ion beam were conducted in different plasma regions of TORPEX. In the third part of the Thesis, numerical simulations are used to interpret the measured fast ion beam behavior. It is shown that a simple single particle equation of motion explains the beam behavior in the experiments in the absence of plasma. To explain the fast ion beam experiments with the plasma a turbulent electric field must be used. The model that takes into account this turbulent electrical field qualitatively explains the shape of the fast ion current density profile in the different plasma regions of TORPEX. The vertically elongated fast ion current density profiles are explained by a spread in the fast ion velocity distribution. The theoretically predicted radial fast ion beam spreading due to the turbulent electric field was observed in the experiment. (author)
Expansion of parameter space for Toroidal Alfven Eigenmode experiments in TFTR
Energy Technology Data Exchange (ETDEWEB)
Wong, K.L.; Wilson, J.R.; Chang, Z.Y.; Fredrickson, E.; Hammett, G.W.; Bush, C.; Nazikian, R.; Phillips, C.K.; Snipes, J.; Taylor, G.
1993-05-01
Several techniques were used to excite toroidal Alfven Eigenmodes in the Tokamak Fusion Test Reactor (TFTR) at magnetic fields above 10 kG. These involve pellet injection to raise the plasma density, variation of plasma current to change the energetic ion orbit and the q-profile, and ICRF heating to produce energetic hydrogen ions at velocities comparable to 3.5 MeV alpha particles. These experimental results are presented and relevance to fusion reactors are discussed.
Perturbing macroscopic magnetohydrodynamic stability for toroidal plasmas
Comer, Kathryn J.
We have introduced a new perturbative technique to rapidly explore the dependence of long wavelength ideal magnetohydrodynamic (MHD) instabilities on equilibrium profiles, shaping properties, and wall parameters. Traditionally, these relations are studied with numerical parameter scans using computationally intensive stability codes. Our perturbative technique first finds the equilibrium and stability using traditional methods. Subsequent small changes in the original equilibrium parameters change the stability. We quickly find the new stability with an expansion of the energy principle, rather than with another run of the stability codes. We first semi-analytically apply the technique to the screw pinch after eliminating compressional Alfven wave effects. The screw pinch results validate the approach, but also indicate that allowable perturbations to equilibria with certain features may be restricted. Next, we extend the approach to toroidal geometry using experimental equilibria and a simple constructed equilibrium, with the ideal MHD stability code GATO. Stability properties are successfully predicted from perturbed toroidal equilibria when only the vacuum beyond the plasma is perturbed (through wall parameter variations), rather than the plasma itself. Small plasma equilibrium perturbations to both experimental and simple equilibria result in very large errors to the predicted stability, and valid results are found only over a narrow range of most perturbations. Despite the large errors produced when changing plasma parameters, the wall perturbations revealed two useful applications of this technique. Because the calculations are non-iterative matrix multiplications, the convergence issues that can disrupt a full MHD stability code are absent. Marginal stability, therefore, is much easier to find with the perturbative technique. Also, the perturbed results can be input as the initial guess for the eigenvalue for a full stability code, and improve subsequent
International Nuclear Information System (INIS)
Jia Manni; Zhong, F.C.; Sun, Y.W.; Wang, L.; Gan, K.
2015-01-01
A numerical code using field line tracing for modeling the three-dimensional magnetic field topology under resonant magnetic perturbations (RMPs) has been developed and applied in Experimental Advanced Superconducting Tokamak (EAST) 2014 campaign. Currently, the model is simplified by using vacuum paradigm and neglecting the toroidal field ripple. The modeling result predicts that the possible strike point splitting on plasma facing component and the lobes like structure on the boundary are observable in various diagnostics at different locations. lt is shown that the strike point splitting strongly depends on the edge stochasticity, which is a combined effect of both perturbation spectrum and equi librium properties. In a lower single null configuration, it is found that RMP may also change the magnetic structure near the upper x-point and form a similar strike point splitting on the upper divertor. It depends on the distance between the two separatrix, which threshold value depends on both the RMP strength and the equilibrium properties. To examine the RMP system on EAST and its effect on plasmas, some experiments with RMPs were hold in the 2014 campaign. The static and rotational perturbation were both tested and results confirm the RMP efficiency. Particle flux profiles on divertor targets measured by divertor probes had verified the existing strike point splitting induced by RMPs. The results are consistent with the numerical modeling within measurement uncertainties and confirm the edge stochasticity induced by RMPs. (author)
Interaction of a spheromak-like compact toroid with a high beta spherical tokamak plasma
International Nuclear Information System (INIS)
Hwang, D.Q.; McLean, H.S.; Baker, K.L.; Evans, R.W.; Horton, R.D.; Terry, S.D.; Howard, S.; Schmidt, G.L.
2000-01-01
Recent experiments using accelerated spheromak-like compact toroids (SCTs) to fuel tokamak plasmas have quantified the penetration mechanism in the low beta regime; i.e. external magnetic field pressure dominates plasma thermal pressure. However, fusion reactor designs require high beta plasma and, more importantly, the proper plasma pressure profile. Here, the effect of the plasma pressure profile on SCT penetration, specifically, the effect of diamagnetism, is addressed. It is estimated that magnetic field pressure dominates penetration even up to 50% local beta. The combination of the diamagnetic effect on the toroidal magnetic field and the strong poloidal field at the outer major radius of a spherical tokamak will result in a diamagnetic well in the total magnetic field. Therefore, the spherical tokamak is a good candidate to test the potential trapping of an SCT in a high beta diamagnetic well. The diamagnetic effects of a high beta spherical tokamak discharge (low aspect ratio) are computed. To test the penetration of an SCT into such a diamagnetic well, experiments have been conducted of SCT injection into a vacuum field structure which simulates the diamagnetic field effect of a high beta tokamak. The diamagnetic field gradient length is substantially shorter than that of the toroidal field of the tokamak, and the results show that it can still improve the penetration of the SCT. Finally, analytic results have been used to estimate the effect of plasma pressure on penetration, and the effect of plasma pressure was found to be small in comparison with the magnetic field pressure. The penetration condition for a vacuum field only is reported. To study the diamagnetic effect in a high beta plasma, additional experiments need to be carried out on a high beta spherical tokamak. (author)
Energy Technology Data Exchange (ETDEWEB)
Cavalcanti, E.; Castro, E.; Malbouisson, A.P.C. [Centro Brasileiro de Pesquisas Fisicas/MCTI, Rio de Janeiro, RJ (Brazil); Linhares, C.A. [Universidade do Estado do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, RJ (Brazil)
2017-10-15
A scalar model is built, as a quantum field theory defined on a toroidal topology, to describe a phase transition in films subjected to periodic boundary conditions and influenced by an external and constant magnetic field. Criticality is studied and the relations between the critical temperature, the film thickness, the magnetic field strength and the chemical potential are investigated. Since the model describes a second-order phase transition a comparison with the Ginzburg-Landau theory is made. (orig.)
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
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
Isomorphic routing on a toroidal mesh
Mao, Weizhen; Nicol, David M.
1993-01-01
We study a routing problem that arises on SIMD parallel architectures whose communication network forms a toroidal mesh. We assume there exists a set of k message descriptors (xi, yi), where (xi, yi) indicates that the ith message's recipient is offset from its sender by xi hops in one mesh dimension, and yi hops in the other. Every processor has k messages to send, and all processors use the same set of message routing descriptors. The SIMD constraint implies that at any routing step, every processor is actively routing messages with the same descriptors as any other processor. We call this isomorphic routing. Our objective is to find the isomorphic routing schedule with least makespan. We consider a number of variations on the problem, yielding complexity results from O(k) to NP-complete. Most of our results follow after we transform the problem into a scheduling problem, where it is related to other well-known scheduling problems.
Distance statistics in large toroidal maps
Guitter, E.
2010-04-01
We compute a number of distance-dependent universal scaling functions characterizing the distance statistics of large maps of genus one. In particular, we obtain explicitly the probability distribution for the length of the shortest non-contractible loop passing via a random point in the map, and that for the distance between two random points. Our results are derived in the context of bipartite toroidal quadrangulations, using their coding by well-labeled 1-trees, which are maps of genus one with a single face and appropriate integer vertex labels. Within this framework, the distributions above are simply obtained as scaling limits of appropriate generating functions for well-labeled 1-trees, all expressible in terms of a small number of basic scaling functions for well-labeled plane trees.
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
Compact toroid development, activity plan for spheromaks
International Nuclear Information System (INIS)
1984-06-01
This document contains the description, goals, status, plans, and approach for the investigation of the properties of a magnetic configuration for plasma confinement identified as the spheromak. This component of the magnetic fusion development program has been characterized by its potential for physical compactness and a flexible range of output power. The included material represents the second phase of spheromak program planning. The first was completed in February 1983 and was reported in DOE/ER-0160, Compact Toroid Development. This planning builds on that previous report and concentrates on the detailed plans for the next several years of the current DOE sponsored program. It has been deliberately restricted to the experimental and theoretical efforts possible within the present scale of effort. A third phase of this planning exercise will examine the subsequent effort and resources needed to achieve near-term (1987 to 1990) spheromak technical objectives
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
Petascale Parallelization of the Gyrokinetic Toroidal Code
Energy Technology Data Exchange (ETDEWEB)
Ethier, Stephane; Adams, Mark; Carter, Jonathan; Oliker, Leonid
2010-05-01
The Gyrokinetic Toroidal Code (GTC) is a global, three-dimensional particle-in-cell application developed to study microturbulence in tokamak fusion devices. The global capability of GTC is unique, allowing researchers to systematically analyze important dynamics such as turbulence spreading. In this work we examine a new radial domain decomposition approach to allow scalability onto the latest generation of petascale systems. Extensive performance evaluation is conducted on three high performance computing systems: the IBM BG/P, the Cray XT4, and an Intel Xeon Cluster. Overall results show that the radial decomposition approach dramatically increases scalability, while reducing the memory footprint - allowing for fusion device simulations at an unprecedented scale. After a decade where high-end computing (HEC) was dominated by the rapid pace of improvements to processor frequencies, the performance of next-generation supercomputers is increasingly differentiated by varying interconnect designs and levels of integration. Understanding the tradeoffs of these system designs is a key step towards making effective petascale computing a reality. In this work, we examine a new parallelization scheme for the Gyrokinetic Toroidal Code (GTC) [?] micro-turbulence fusion application. Extensive scalability results and analysis are presented on three HEC systems: the IBM BlueGene/P (BG/P) at Argonne National Laboratory, the Cray XT4 at Lawrence Berkeley National Laboratory, and an Intel Xeon cluster at Lawrence Livermore National Laboratory. Overall results indicate that the new radial decomposition approach successfully attains unprecedented scalability to 131,072 BG/P cores by overcoming the memory limitations of the previous approach. The new version is well suited to utilize emerging petascale resources to access new regimes of physical phenomena.
Near Field Environment Process Model Report
Energy Technology Data Exchange (ETDEWEB)
R.A. Wagner
2000-11-14
Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.
Subgrid geoelectric field specification for GIC modeling
Butala, M.; Grawe, M.; Kamalabadi, F.; Makela, J. J.
2017-12-01
Geomagnetically induced currents (GICs) result from surface geomagnetic field (ěc{B}) variation driven by space weather disturbances. For the most intense disturbances, the consequences can range from power grid instability to even widespread failure. Modeling GICs to assess vulnerability requires the specification of the surface geoelectric field (ěc{E}) at all spatial locations coincident with the electric power system. In this study, we investigate how to best reproduce ěc{E} given the available sparse, irregularly spaced magnetometer measurements of ěc{B} and suitable electromagnetic transfer functions (EMTFs) to transform the local ěc{B} to ěc{E}. The assessment is made against ground truth from publicly available ěc{E} measurements provided by the EarthScope magnetotelluric (MT) array, a set of 7 fixed and several transportable joint ěc{B} and ěc{E} sensors. The scope of this study spans several dimensions: geomagnetic disturbance intensity, spatial interpolation scheme, and EMTF type, i.e., 1-D models based on studies of local geology and 3-D models derived from the EarthScope MT data.
Optimization Models for Petroleum Field Exploitation
Energy Technology Data Exchange (ETDEWEB)
Jonsbraaten, Tore Wiig
1998-12-31
This thesis presents and discusses various models for optimal development of a petroleum field. The objective of these optimization models is to maximize, under many uncertain parameters, the project`s expected net present value. First, an overview of petroleum field optimization is given from the point of view of operations research. Reservoir equations for a simple reservoir system are derived and discretized and included in optimization models. Linear programming models for optimizing production decisions are discussed and extended to mixed integer programming models where decisions concerning platform, wells and production strategy are optimized. Then, optimal development decisions under uncertain oil prices are discussed. The uncertain oil price is estimated by a finite set of price scenarios with associated probabilities. The problem is one of stochastic mixed integer programming, and the solution approach is to use a scenario and policy aggregation technique developed by Rockafellar and Wets although this technique was developed for continuous variables. Stochastic optimization problems with focus on problems with decision dependent information discoveries are also discussed. A class of ``manageable`` problems is identified and an implicit enumeration algorithm for finding optimal decision policy is proposed. Problems involving uncertain reservoir properties but with a known initial probability distribution over possible reservoir realizations are discussed. Finally, a section on Nash-equilibrium and bargaining in an oil reservoir management game discusses the pool problem arising when two lease owners have access to the same underlying oil reservoir. Because the oil tends to migrate, both lease owners have incentive to drain oil from the competitors part of the reservoir. The discussion is based on a numerical example. 107 refs., 31 figs., 14 tabs.
A matrix model from string field theory
Directory of Open Access Journals (Sweden)
Syoji Zeze
2016-09-01
Full Text Available We demonstrate that a Hermitian matrix model can be derived from level truncated open string field theory with Chan-Paton factors. The Hermitian matrix is coupled with a scalar and U(N vectors which are responsible for the D-brane at the tachyon vacuum. Effective potential for the scalar is evaluated both for finite and large N. Increase of potential height is observed in both cases. The large $N$ matrix integral is identified with a system of N ZZ branes and a ghost FZZT brane.
Non standard analysis, polymer models, quantum fields
International Nuclear Information System (INIS)
Albeverio, S.
1984-01-01
We give an elementary introduction to non standard analysis and its applications to the theory of stochastic processes. This is based on a joint book with J.E. Fenstad, R. Hoeegh-Krohn and T. Lindstroeem. In particular we give a discussion of an hyperfinite theory of Dirichlet forms with applications to the study of the Hamiltonian for a quantum mechanical particle in the potential created by a polymer. We also discuss new results on the existence of attractive polymer measures in dimension d 1 2 phi 2 2 )sub(d)-model of interacting quantum fields. (orig.)
Migration model for the near field
International Nuclear Information System (INIS)
Andersson, G.; Rasmusson, A.; Neretnieks, I.
1982-11-01
The near field model describes the transport of substances dissolved in the groundwater to and from a canister in which radioactive materials are stored. The migration of substances that can cause corrosion (oxidants) of the canister is described by means of a mathematical model. The model takes into account diffusion through the buffer material and water flow in the rock fractures. Two distinct transport resistances can be distinguished in this transport process. The first consists of the diffusion resistance in the buffer material and the second arises due to diffusion resistance in the flowing water in the thin fractures in the rock. The model can also be used to calculate the non-steady-state phase of the inward or outward transport of dissolved species. The model has also been used to calculate how a redox front caused by radiolytically produced oxidants moves out through the clay and into the rock. It has been shown that the migration rate of the redox front can be calculated with good accuracy by means of simple mass balance computations. The transport of radiolytically formed hydrogen away from the fuel has been calculated. When dissolved in the water, hydrogen can be transported through the clay barrier by means of diffusion without the partial pressure of the hydrogen exceeding the hydrostatic pressure. (author)
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.
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
Field space entanglement entropy, zero modes and Lifshitz models
Huffel, Helmuth; Kelnhofer, Gerald
2017-12-01
The field space entanglement entropy of a quantum field theory is obtained by integrating out a subset of its fields. We study an interacting quantum field theory consisting of massless scalar fields on a closed compact manifold M. To this model we associate its Lifshitz dual model. The ground states of both models are invariant under constant shifts. We interpret this invariance as gauge symmetry and subject the models to proper gauge fixing. By applying the heat kernel regularization one can show that the field space entanglement entropies of the massless scalar field model and of its Lifshitz dual are agreeing.
Field space entanglement entropy, zero modes and Lifshitz models
Directory of Open Access Journals (Sweden)
Helmuth Huffel
2017-12-01
Full Text Available The field space entanglement entropy of a quantum field theory is obtained by integrating out a subset of its fields. We study an interacting quantum field theory consisting of massless scalar fields on a closed compact manifold M. To this model we associate its Lifshitz dual model. The ground states of both models are invariant under constant shifts. We interpret this invariance as gauge symmetry and subject the models to proper gauge fixing. By applying the heat kernel regularization one can show that the field space entanglement entropies of the massless scalar field model and of its Lifshitz dual are agreeing.
Computer Forensics Field Triage Process Model
Directory of Open Access Journals (Sweden)
Marcus K. Rogers
2006-06-01
Full Text Available With the proliferation of digital based evidence, the need for the timely identification, analysis and interpretation of digital evidence is becoming more crucial. In many investigations critical information is required while at the scene or within a short period of time - measured in hours as opposed to days. The traditional cyber forensics approach of seizing a system(s/media, transporting it to the lab, making a forensic image(s, and then searching the entire system for potential evidence, is no longer appropriate in some circumstances. In cases such as child abductions, pedophiles, missing or exploited persons, time is of the essence. In these types of cases, investigators dealing with the suspect or crime scene need investigative leads quickly; in some cases it is the difference between life and death for the victim(s. The Cyber Forensic Field Triage Process Model (CFFTPM proposes an onsite or field approach for providing the identification, analysis and interpretation of digital evidence in a short time frame, without the requirement of having to take the system(s/media back to the lab for an in-depth examination or acquiring a complete forensic image(s. The proposed model adheres to commonly held forensic principles, and does not negate the ability that once the initial field triage is concluded, the system(s/storage media be transported back to a lab environment for a more thorough examination and analysis. The CFFTPM has been successfully used in various real world cases, and its investigative importance and pragmatic approach has been amply demonstrated. Furthermore, the derived evidence from these cases has not been challenged in the court proceedings where it has been introduced. The current article describes the CFFTPM in detail, discusses the model’s forensic soundness, investigative support capabilities and practical considerations.
DEFF Research Database (Denmark)
Ha, B. N.; Stoneking,, M. R.; Marler, Joan
2009-01-01
Measurements of the image charge induced on electrodes provide the primary means of diagnosing plasmas in the Lawrence Non-neutral Torus II (LNT II) [Phys. Rev. Lett. 100, 155001 (2008)]. Therefore, it is necessary to develop techniques that determine characteristics of the electron plasma from...... features of the induced image charge signal. This paper presents a numerical study which finds that the frequency of the image charge signal due to the toroidal version of the m=1 diocotron mode is proportional to the total trapped charge and inversely proportional to magnetic field strength......, as in the cylindrical case. In the toroidal case, additional information about the m=1 motion of the plasma can be obtained by analysis of the image charge signal amplitude and shape. Finally, results from the numerical simulations are compared to experimental data from the LNT II and plasma characteristics...
International Nuclear Information System (INIS)
Rogister, A.; Hasselberg, G.; Waelbroeck, F.; Weiland, J.
1987-12-01
A self-consistent transport code is used to evaluate how plasma confinement in tokamaks is influenced by the microturbulent fields which are excited by the dissipative trapped electron (DTE) instability. As shown previously, the saturation theory on which the code is based has been developed from first principles. The toroidal coupling resulting from the ion magnetic drifts is neglected; arguments are presented to justify this approximation. The numerical results reproduce well the neo-Alcator scaling law observed experimentally - e.g. in TEXTOR - in non detached ohmic discharges, the confinement degradation which results when auxiliary heating is applied, as well as a large number of other experimental observations. We also assess the possible impact of the toroidal ion temperature gradient mode on energy confinement by estimating the ion thermal flux with the help of the mixing length approximation. (orig./GG)
Energy Technology Data Exchange (ETDEWEB)
Galkowski, A. [Institute of Atomic Energy, Otwock-Swierk (Poland)
1994-12-31
Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad`s ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs.
Diocotron and Trivelpiece-Gould mode behavior in toroidal electron plasma
Stoneking, M. R.; Darrell, J. W.; Exarhos, S. A.; Patterson, A. S.; Price, M. J.; Wright, A. H.
2013-03-01
Electron plasma confined in a purely toroidal magnetic field supports analogs of the electrostatic normal modes observed in cylindrical traps - namely diocotron and Trivelpiece-Gould waves. The Lawrence Non-neutral Torus II (LNT II) device is used to study such waves. Electron plasma with densities in the range of 107 cm-3 persisting for about 1 second are produced in LNT II with high vacuum conditions (G. The plasma is diagnosed by monitoring image charge flow to sectors of the symmetric conducting boundary (major radius of 18 cm and minor radius of 3.8 cm). Damping of the m=1 (k=0) diocotron mode is explored to assess the extent to which rotational and/or magnetic pumping transport mechanisms are operative in toroidal electron plasma. Resonant standing wave plasma modes (m=0) are excited in order to determine the Trivelpiece-Gould dispersion relation. This work is supported by the National Science Foundation Grant PHY-0812893.
Wind gust models derived from field data
Gawronski, W.
1995-01-01
Wind data measured during a field experiment were used to verify the analytical model of wind gusts. Good coincidence was observed; the only discrepancy occurred for the azimuth error in the front and back winds, where the simulated errors were smaller than the measured ones. This happened because of the assumption of the spatial coherence of the wind gust model, which generated a symmetric antenna load and, in consequence, a low azimuth servo error. This result indicates a need for upgrading the wind gust model to a spatially incoherent one that will reflect the real gusts in a more accurate manner. In order to design a controller with wind disturbance rejection properties, the wind disturbance should be known at the input to the antenna rate loop model. The second task, therefore, consists of developing a digital filter that simulates the wind gusts at the antenna rate input. This filter matches the spectrum of the measured servo errors. In this scenario, the wind gusts are generated by introducing white noise to the filter input.
Oksala, M. E.; Silvester, J.; Kochukhov, O.; Neiner, C.; Wade, G. A.; the MiMeS Collaboration
2018-01-01
Previous studies of the chemically peculiar Bp star 36 Lyn revealed a moderately strong magnetic field, circumstellar material and inhomogeneous surface abundance distributions of certain elements. We present in this paper an analysis of 33 high signal-to-noise ratio, high-resolution Stokes IV observations of 36 Lyn obtained with the Narval spectropolarimeter at the Bernard Lyot Telescope at Pic du Midi Observatory. From these data, we compute new measurements of the mean longitudinal magnetic field, Bℓ, using the multiline least-squares deconvolution (LSD) technique. A rotationally phased Bℓ curve reveals a strong magnetic field, with indications for deviation from a pure dipole field. We derive magnetic maps and chemical abundance distributions from the LSD profiles, produced using the Zeeman-Doppler imaging code INVERSLSD. Using a spherical harmonic expansion to characterize the magnetic field, we find that the harmonic energy is concentrated predominantly in the dipole mode (ℓ = 1), with significant contribution from both the poloidal and toroidal components. This toroidal field component is predicted theoretically, but not typically observed for Ap/Bp stars. Chemical abundance maps reveal a helium enhancement in a distinct region where the radial magnetic field is strong. Silicon enhancements are located in two regions, also where the radial field is stronger. Titanium and iron enhancements are slightly offset from the helium enhancements, and are located in areas where the radial field is weak, close to the magnetic equator.
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.
International Nuclear Information System (INIS)
Cherepanov, K.V.; Kukushkin, A.B.
2005-01-01
Numerical studies of the contribution of suprathermal electrons to electron cyclotron radiation (ECR) transport in hot (Te > 10 keV) plasmas confined by a strong toroidal magnetic field (B > 5 T) are reported. The respective code (Proc. 14th IAEA Conf. PPCF, Wuerzburg, 1992, v.2, p.35) which, for maxwellian electron velocity distribution (EVD) with inhomogeneous temperature/density, has been tested against well-known numerical and semi-analytical codes by S. Tamor, is now applied to solving the following two problems for ITER-like conditions. (1) Spatial profile of the net radiated power density, P EC (r), is found to be strongly sensitive to the presence of suprathermal electrons. This enables us to evaluate allowable limits for local rise of effective temperature/density of suprathermal electrons (in terms of bi-maxwellian EVD). (2) Self-consistent modeling of the ECR transport and the kinetics of suprathermal electrons gives spatial profile of deviations from maxwellian EVD, caused by the transport of plasma's self EC radiation. These kinetic effects work ultimately for the global flattening of the P EC (r) profile: a lowering, in the core, and a rise, in the periphery. For ITER-like conditions, these effects upon P EC (r) appear to be small. The results of treating the above two tasks suggest the necessity of solving self-consistently the problems of (i) ECRH and ECCD optimization and (ii) ECR transport in the entire range of radiation frequency, when strong enough suprathermals may be produced. (author)
International Nuclear Information System (INIS)
Chapin, D.L.
1976-03-01
Differences in neutron fluxes and nuclear reaction rates in a noncircular fusion reactor blanket when analyzed in cylindrical and toroidal geometry are studied using Monte Carlo. The investigation consists of three phases--a one-dimensional calculation using a circular approximation to a hexagonal shaped blanket; a two-dimensional calculation of a hexagonal blanket in an infinite cylinder; and a three-dimensional calculation of the blanket in tori of aspect ratios 3 and 5. The total blanket reaction rate in the two-dimensional model is found to be in good agreement with the circular model. The toroidal calculations reveal large variations in reaction rates at different blanket locations as compared to the hexagonal cylinder model, although the total reaction rate is nearly the same for both models. It is shown that the local perturbations in the toroidal blanket are due mainly to volumetric effects, and can be predicted by modifying the results of the infinite cylinder calculation by simple volume factors dependent on the blanket location and the torus major radius
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.
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.
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
Dynamics of the Random Field Ising Model
Xu, Jian
The Random Field Ising Model (RFIM) is a general tool to study disordered systems. Crackling noise is generated when disordered systems are driven by external forces, spanning a broad range of sizes. Systems with different microscopic structures such as disordered mag- nets and Earth's crust have been studied under the RFIM. In this thesis, we investigated the domain dynamics and critical behavior in two dipole-coupled Ising ferromagnets Nd2Fe14B and LiHoxY 1-xF4. With Tc well above room temperature, Nd2Fe14B has shown reversible disorder when exposed to an external transverse field and crosses between two universality classes in the strong and weak disorder limits. Besides tunable disorder, LiHoxY1-xF4 has shown quantum tunneling effects arising from quantum fluctuations, providing another mechanism for domain reversal. Universality within and beyond power law dependence on avalanche size and energy were studied in LiHo0.65Y0.35 F4.
Geomagnetic Core Field Secular Variation Models
DEFF Research Database (Denmark)
Gillet, N.; Lesur, V.; Olsen, Nils
2010-01-01
We analyse models describing time changes of the Earth’s core magnetic field (secular variation) covering the historical period (several centuries) and the more recent satellite era (previous decade), and we illustrate how both the information contained in the data and the a priori information...... (regularisation) affect the result of the ill-posed geomagnetic inverse problem. We show how data quality, frequency and selection procedures govern part of the temporal changes in the secular variation norms and spectra, which are sometimes difficult to dissociate from true changes of the core state. We...... highlight the difficulty of resolving the time variability of the high degree secular variation coefficients (i.e. the secular acceleration), arising for instance from the challenge to properly separate sources of internal and of external origin. In addition, the regularisation process may also result...
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
International Nuclear Information System (INIS)
Elfimov, A.G.; Nekrasov, F.M.
1992-07-01
A method for the analytical treatment of the toroidal plasma electron dielectric permeability tensor is developed. Simple expressions for some limiting cases are obtained. Electron Landau and TTMP absorption of the fast waves in tokamaks are discussed in terms of 'nonlocality' effects, including the effect of trapped and untrapped particles bounce resonances. Additional dissipation of the fast waves in tokamaks is founded in a comparison with cylindrical model Landau damping. (orig.)
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...
Lattice Ising model in a field: E8 scattering theory
Bazhanov, V.V.; Nienhuis, B.; Warnaar, S.O.
1994-01-01
Zamolodchikov found an integrable field theory related to the Lie algebra E8, which describes the scaling limit of the Ising model in a magnetic field. He conjectured that there also exist solvable lattice models based on E8 in the universality class of the Ising model in a field. The dilute A3
Superconducting toroidal combined-function magnet for a compact ion beam cancer therapy gantry
International Nuclear Information System (INIS)
Robin, D.S.; Arbelaez, D.; Caspi, S.; Sun, C.; Sessler, A.; Wan, W.; Yoon, M.
2011-01-01
A superconducting, combined-function, 5 T, 90°, toroidal magnet with a large bore is described in this paper. This magnet is designed to be the last and most difficult part of a compact superconducting magnet-based carbon gantry optics for ion beam cancer therapy. The relatively small size of this toroidal magnet allows for a gantry the size of which is smaller or at least comparable to that of a proton gantry. The gantry design places the toroidal magnet between the scanning magnets and the patient, that is the scanning magnets are placed midway through the gantry. By optimizing the coil winding configuration of this magnet, near point-to-parallel optics is achieved between the scanning magnets and the patient; while at the same time there is only a small distortion of the beam-shape when scanning. We show that the origin of the beam-shape distortion is the strong sextupole components, whose effects are greatly pronounced when the beam is widely steered in the magnet. A method to correct such an undesirable effect is suggested and demonstrated by a numerical particle tracking through the calculated three-dimensional magnetic field.
Energy Technology Data Exchange (ETDEWEB)
Wahlberg, C, E-mail: Christer.Wahlberg@fysast.uu.s [Department of Physics and Astronomy, EURATOM/VR Fusion Association, PO Box 516, Uppsala University, SE-751 20 Uppsala (Sweden)
2009-08-15
This paper analyses low-frequency magnetohydrodynamic (MHD) modes, especially the geodesic acoustic modes (GAMs), in toroidal plasmas with large aspect ratio and circular cross section, including the effects of toroidal plasma rotation. A system of equations describing MHD modes with frequency of the order of the sound frequency in such plasmas is derived from the Frieman-Rotenberg equation, using a technique where the plasma perturbation xi and the perturbed magnetic field Q are expanded separately in the inverse aspect ratio epsilon = r/R, where r and R denote the minor and major radii of the plasma torus, respectively. The large-scale, ideal MHD properties of the GAM induced by toroidal rotation (Wahlberg 2008 Phys. Rev. Lett. 101 115003) are thereafter analysed in more detail employing this system of equations. It is shown that both the axisymmetric GAMs existing in rotating plasmas are localized on a specific magnetic surface only to leading order in epsilon, and that a 'halo' consisting of finite components of both xi and Q with dominant poloidal mode numbers m = +-2 appears outside this magnetic surface to higher orders in epsilon.
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)
Near-field/altered-zone models report
Energy Technology Data Exchange (ETDEWEB)
Hardin, E. L., LLNL
1998-03-01
nonlithophysal and lower lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF
Model for predicting mountain wave field uncertainties
Damiens, Florentin; Lott, François; Millet, Christophe; Plougonven, Riwal
2017-04-01
Studying the propagation of acoustic waves throughout troposphere requires knowledge of wind speed and temperature gradients from the ground up to about 10-20 km. Typical planetary boundary layers flows are known to present vertical low level shears that can interact with mountain waves, thereby triggering small-scale disturbances. Resolving these fluctuations for long-range propagation problems is, however, not feasible because of computer memory/time restrictions and thus, they need to be parameterized. When the disturbances are small enough, these fluctuations can be described by linear equations. Previous works by co-authors have shown that the critical layer dynamics that occur near the ground produces large horizontal flows and buoyancy disturbances that result in intense downslope winds and gravity wave breaking. While these phenomena manifest almost systematically for high Richardson numbers and when the boundary layer depth is relatively small compare to the mountain height, the process by which static stability affects downslope winds remains unclear. In the present work, new linear mountain gravity wave solutions are tested against numerical predictions obtained with the Weather Research and Forecasting (WRF) model. For Richardson numbers typically larger than unity, the mesoscale model is used to quantify the effect of neglected nonlinear terms on downslope winds and mountain wave patterns. At these regimes, the large downslope winds transport warm air, a so called "Foehn" effect than can impact sound propagation properties. The sensitivity of small-scale disturbances to Richardson number is quantified using two-dimensional spectral analysis. It is shown through a pilot study of subgrid scale fluctuations of boundary layer flows over realistic mountains that the cross-spectrum of mountain wave field is made up of the same components found in WRF simulations. The impact of each individual component on acoustic wave propagation is discussed in terms of
Transport and dynamcis in toroidal fusion systems. Final report, 1992--1995
International Nuclear Information System (INIS)
Schnack, D.D.
1995-01-01
This document is organized as follows. Discussions are presented on the properties of structured and unstructured meshes, and the data structures useful for describing them. Issues related to the triangulation of an arbitrary set of points in a plane are also discussed. A derivation is made of a finite volume approximation to the resistive MHD equations suitable for use on an unstructured, triangular mesh in toroidal geometry. Boundary conditions are discussed. The specific MHD model, and its implementation on the unstructured mesh, is discussed. A discussion is presented of methods of time integration, and descriptions are given for implementation of semi-implicit and fully implicit algorithms. Examples of the application of the method are given. Included are standard, two- dimensional hydrodynamic and MHD shock problems, as well as applications of the method to the equilibrium and stability of toroidal fusion plasmas in two and three dimensions. The initial results with mesh adaptation are also described
A representation of toroidal MHD in terms of stream functions and potentials
International Nuclear Information System (INIS)
Maschke, E.K.; Morros Tosas, J.
1988-03-01
An exact representation of toroidal magneto-hydrodynamics is proposed, in which the electromagnetic and the velocity fields are represented in terms of stream functions and potentials, without assuming any spatial symmetries. Two important features of this representation are the use of a time-independent but otherwise arbitrary reference field B O , and the fact that the vector product of the velocity V with B 0 , and not V itself, is represented in terms of stream functions. In this way the equations take a form, which allows relatively easy physical interpretation and is well suited for deriving reduced MHD equations for particular stability problems
Dielectric tensor operator of hot plasmas in toroidal axisymmetric systems
International Nuclear Information System (INIS)
Brunner, S.; Vaclavik, J.
1992-08-01
Kinetic theory is used to develop equations describing dynamics of small-amplitude electromagnetic perturbations in toroidal axisymmetric plasmas. The closed Vlasov-Maxwell equations are first solved for a hot stationary plasma using the expansion in the small parameter ε e =ρ/L, where ρ is the Larmor radius and L a characteristic length scale of the stationary state. The ordering and additional assumptions are specified so as to obtain the well-known Grad-Shafranov equation. The dielectric tensor of such a plasma is then derived. The Vlasov equation for the perturbed distribution function is solved by the expansion in the small parameters ε e and ε p =ρ/λ, where λ is a characteristic wavelength of the perturbing electromagnetic field. The solution is obtained up to the first order in ε e and the second order in ε p . By integrating the resulting distribution function over velocity space, an explicit expression for the tensor is derived in the form of a two-dimensional partial differential operator. The operator is shown to possess the proper symmetry corresponding to the energy conservation law. (author) 6 refs
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.
Expansion Of The Magnetic Flux Density Field In Toroidal Harmonics
Gambini, Laura; Bottura, Luca; Felcini, Enrico
CERN (Conseil Européen pour la Recherche Nucléaire) is recognized worldwide as the main research laboratory in the ﬁeld of particle physics. Inevitably, all this requires the use of the most advanced technologies, both from the point of view of the instruments and the analytical descriptive methods. One of the numerous potentials of the work carried out at CERN concerns the possibility of exploiting the aforementioned technologies even in contexts distant from the physics of particles, with the result of inﬂuencing the technological advancement of many areas. For example, one of the most widely employed theories at CERN, regarding the analytical description of the magnetic ﬂux density inside solenoidal magnets (or approximable as such under suitable assumptions) for the acceleration of particles, is the so-called multipole expansion. This is a two-dimensional or three-dimensional analysis of the distribution of the magnetic ﬂux density generated by the windings of a magnet. The magnet in question ca...
Edge and divertor physics with reversed toroidal field in JET
Czech Academy of Sciences Publication Activity Database
Pitts, R. A.; Andrew, P.; Bonnin, X.; Chankin, A.V.; Corre, Y.; Corrigan, G.; Coster, D.; Ďuran, Ivan; Eich, T.; Erents, S. K.; Fundameski, W.; Huber, A.; Jachmich, S.; Kirnev, G.; Lehnen, M.; Lomas, P. J.; Loarte, A.; Matthews, G. F.; Rapp, J.; Silva, C.; Stamp, M.F.; Strachan, J.D.; Tsitrone, E.
337-339, č. 16 (2005), s. 146-153 ISSN 0022-3115. [Plasma Surface Interactions /16./. Portland, 24.5.2005-28.5.2005] Institutional research plan: CEZ:AV0Z20430508 Keywords : SOL * Particle drifts * JET * Plasma flow * Divertor Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.414, year: 2005
Ballooning modes or Fourier modes in a toroidal plasma?
International Nuclear Information System (INIS)
Connor, J.W.; Taylor, J.B.
1987-01-01
The relationship between two different descriptions of eigenmodes in a torus is investigated. In one the eigenmodes are similar to Fourier modes in a cylinder and are highly localized near a particular rational surface. In the other they are the so-called ballooning modes that extend over many rational surfaces. Using a model that represents both drift waves and resistive interchanges the transition from one of these structures to the other is investigated. In this simplified model the transition depends on a single parameter which embodies the competition between toroidal coupling of Fourier modes (which enhances ballooning) and variation in frequency of Fourier modes from one rational surface to another (which diminishes ballooning). As the coupling is increased each Fourier mode acquires a sideband on an adjacent rational surface and these sidebands then expand across the radius to form the extended mode described by the conventional ballooning mode approximation. This analysis shows that the ballooning approximation is appropriate for drift waves in a tokamak but not for resistive interchanges in a pinch. In the latter the conventional ballooning effect is negligible but they may nevertheless show a ballooning feature. This is localized near the same rational surface as the primary Fourier mode and so does not lead to a radially extended structure
Families and degenerations of conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Roggenkamp, D.
2004-09-01
In this work, moduli spaces of conformal field theories are investigated. In the first part, moduli spaces corresponding to current-current deformation of conformal field theories are constructed explicitly. For WZW models, they are described in detail, and sigma model realizations of the deformed WZW models are presented. The second part is devoted to the study of boundaries of moduli spaces of conformal field theories. For this purpose a notion of convergence of families of conformal field theories is introduced, which admits certain degenerated conformal field theories to occur as limits. To such a degeneration of conformal field theories, a degeneration of metric spaces together with additional geometric structures can be associated, which give rise to a geometric interpretation. Boundaries of moduli spaces of toroidal conformal field theories, orbifolds thereof and WZW models are analyzed. Furthermore, also the limit of the discrete family of Virasoro minimal models is investigated. (orig.)