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Sample records for act-1 toroidal device

  1. Microwave produced plasma in a Toroidal Device

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Edwards, W. F.; Held, E. D.

    2010-11-01

    A currentless toroidal plasma device exhibits a large range of interesting basic plasma physics phenomena. Such a device is not in equilibrium in a strict magneto hydrodynamic sense. There are many sources of free energy in the form of gradients in plasma density, temperature, the background magnetic field and the curvature of the magnetic field. These free energy sources excite waves and instabilities which have been the focus of studies in several devices in last two decades. A full understanding of these simple plasmas is far from complete. At Utah State University we have recently designed and installed a microwave plasma generation system on a small tokamak borrowed from the University of Saskatchewan, Saskatoon, Canada. Microwaves are generated at 2.45 GHz in a pulsed dc mode using a magnetron from a commercial kitchen microwave oven. The device is equipped with horizontal and vertical magnetic fields and a transformer to impose a toroidal electric field for current drive. Plasmas can be obtained over a wide range of pressure with and without magnetic fields. We present some preliminary measurements of plasma density and potential profiles. Measurements of plasma temperature at different operating conditions are also presented.

  2. Variable control of neutron albedo in toroidal fusion devices

    DOEpatents

    Jassby, D.L.; Micklich, B.J.

    1983-06-01

    This invention pertains to methods of controlling in the steady state, neutron albedo in toroidal fusion devices, and in particular, to methods of controlling the flux and energy distribution of collided neutrons which are incident on an outboard wall of a toroidal fusion device.

  3. System and method of operating toroidal magnetic confinement devices

    DOEpatents

    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.

  4. Toroidal band limiter for a plasma containment device

    DOEpatents

    Kelley, George G.

    1978-01-01

    This invention relates to a toroidal plasma confinement device having poloidal and toroidal magnetic fields for confining a toroidal plasma column with a plasma current induced therein along an endless, circular equilibrium axis in a torus vacuum cavity wherein the improvement comprises the use of a toroidal plasma band limiter mounted within the vacuum cavity in such a manner as to ensure that the plasma energy is distributed more uniformly over the limiter surface thereby avoiding intense local heating of the limiter while at the same time substantially preventing damage to the plasma containment wall of the cavity by the energetic particles diffusing out from the confined plasma. A plurality of poloidal plasma ring limiters are also utilized for containment wall protection during any disruptive instability that might occur during operation of the device.

  5. RF plasma heating in toroidal fusion devices

    SciTech Connect

    Golant, V.E.; Fedorov, V.I. )

    1989-01-01

    The purpose of the present book is to provide, in seven chapters, a unified overview of the methods for rf heating of plasmas in toroidal fusion experiments. In Chapter 1 the problem of plasma heating in tokamaks and stellarators is formulated and the requirements for auxiliary heating techniques are described. This chapter also contains a brief review of the results of research on tokamaks and stellarators. Chapter 2 is devoted to a theoretical description of the principal physical effects involved in the rf heating of plasmas, especially the characteristics of wave propagation, of the mechanisms by which waves are absorbed and plasma heating takes place, and of the nonlinear effects that accompany heating. The primary emphasis is on a qualitative physical picture of these effects. Chapters 3-6, in turn, deal with the major rf heating techniques currently under investigation, electron cyclotron (ECH), ion cyclotron (ICH), lower hybrid (LHH), and Alfven wave heating. In each of these chapters the main schemes for heating are described, the results of theoretical analyses and numerical simulations are discussed, the technology of the heating systems is briefly described, and experimental work published through the end of 1984 is reviewed. Finally, in Chapter 7 the different rf heating techniques are compared; they are contrasted with neutral beam injection, and the feasibility of adiabatic compression as a means of heating plasmas is examined. Separate abstracts were prepared for each chapter of this book. 246 refs.

  6. Plasma Properties of Microwave Produced Plasma in a Toroidal Device

    NASA Astrophysics Data System (ADS)

    Singh, Ajay; Edwards, W. F.; Held, Eric

    2011-10-01

    We have modified a small tokamak, STOR-1M, on loan from University of Saskatchewan, to operate as a low-temperature (~5 eV) toroidal plasma machine with externally induced toroidal magnetic fields ranging from zero to ~50 G. The plasma is produced using microwave discharges at relatively high pressures. Microwaves are produced by a kitchen microwave-oven magnetron operating at 2.45 GHz in continuous operating mode, resulting in pulses ~0.5 s in duration. Initial measurements of plasma formation in this device with and without applied magnetic fields are presented. Plasma density and temperature profiles have been measured using Langmuir probes and the magnetic field profile inside the plasma has been obtained using Hall probes. When the discharge is created with no applied toroidal magnetic field, the plasma does not fill the entire torus due to high background pressure. However, when a toroidal magnetic field is applied, the plasma flows along the applied field, filling the torus. Increasing the applied magnetic field seems to aid plasma formation - the peak density increases and the density gradient becomes steeper. Above a threshold magnetic field, the plasma develops low-frequency density oscillations due to probable excitation of flute modes in the plasma.

  7. System and method of operating toroidal magnetic confinement devices

    DOEpatents

    Chance, Morrell S.; Jardin, Stephen C.; Stix, Thomas H.; Grimm, deceased, Ray C.; Manickam, Janardhan; Okabayashi, Michio

    1987-01-01

    For toroidal magnetic confinement devices the second region of stability against ballooning modes can be accessed with controlled operation. Under certain modes of operation, the first and second stability regions may be joined together. Accessing the second region of stability is accomplished by forming a bean-shaped plasma and increasing the indentation until a critical value of indentation is reached. A pusher coil, located at the inner-major-radius side of the device, is engaged to form a bean-shaped poloidal cross-section in the plasma.

  8. Variable control of neutron albedo in toroidal fusion devices

    DOEpatents

    Jassby, Daniel L.; Micklich, Bradley J.

    1986-01-01

    An arrangement is provided for controlling neutron albedo in toroidal fusion devices having inboard and outboard vacuum vessel walls for containment of the neutrons of a fusion plasma. Neutron albedo material is disposed immediately adjacent the inboard wall, and is movable, preferably in vertical directions, so as to be brought into and out of neutron modifying communication with the fusion neutrons. Neutron albedo material preferably comprises a liquid form, but may also take pebble, stringer and curtain-like forms. A neutron flux valve, rotatable about a vertical axis is also disclosed.

  9. Stability of Small Aspect Ratio Toroidal Hybrid Devices

    NASA Astrophysics Data System (ADS)

    Ware, A. S.; Batchelor, D. B.; Carreras, B. A.; Hirshman, S. P.; Lynch, V. E.; Spong, D. A.; Whitson, J.

    1997-11-01

    The stability properties of small aspect ratio toroidal hybrid (SMARTH) devices are investigated. SMARTH configurations are a hybrid between a stellarator and a tokamak: the poloidal field is provided by both external modulated coils as well as plasma current. Initial studies of these devices focused on configurations with a simple set of modulated circular toroidal field coils.(B. A. Carreras, V. E. Lynch, and A. S. Ware, ORNL/TM-13252, 1996) These configurations have a magnetic well throughout the plasma volume and β limits for these devices are set by ideal ballooning modes. Here, we focus on the effect of finite plasma current on the ideal ballooning stability limit for SMARTH configurations. Preliminary results indicate that adding plasma current raises the stability β threshhold. More recent investigation have focused on configurations optimized solely for maximal particle confinement.(D. A. Spong, et al., 1997 Sherwood Theory Meeting, Poster 3C08) Confinement optimization, however, was deleterious to stability. We will report on progress to include a `stability criteria' in further confinement optimization studies.

  10. Ultimate Diagnostics for the Measurement of Turbulence in Toroidal Devices

    NASA Astrophysics Data System (ADS)

    Park, H.; Mazzucato, E.; Hahm, T. S.; Lee, W. W.; Rewoldt, G.; Synakowski, E.; Domier, C. W.; Luhmann, N. C., Jr.

    1998-11-01

    Relentless efforts in plasma diagnostics concepts (E. Mazzucato, Rev. Sci. Instrum. 69, 1691 (1998), H. Hase, H. Hartfuss,12th HTPD conference, F-16, June 1998.) and technology (R.P. Hsia et al., Rev. Sci. Instrum. 68, 488 (1997).) R&D enable us to design a system capable of simultaneous 3-D imaging of the temperature and density turbulence spectrum in toroidal devices such as tokamak and stellarator. Measurement of multi-dimensional correlation between Te and ne turbulence is extremely important in understanding the current transport model. In this paper, the details of the concept design such as accessibility, machine parameters, detection system and relevant frequencies will be discussed for a various devices. Special attention will be given to obtain ω and k spectra with sufficient spatial resolution so that the results can be readily compared with remarkable visual results produced by gyro-kinetic (GK) and/or gyro-fluid (GF) simulations.

  11. Kinetic and electromagnetic transport processes in toroidal devices

    SciTech Connect

    Moses, R.W.; Schoenberg, K.F.

    1990-01-01

    A brief review of transport processes in toroidal devices is presented. Particular attention is given to radial transport of power by the Poynting's vector and kinetic electron flow. This work is primarily focused on the Reversed Field Pinch (RFP) which holds the added complexity of a dynamo process that sustains poloidal current in the edge region, where the toroidal field is reversed. The experimental observation of superthermal unidirectional electrons in the plasma edge of ZT-40M and HBTX1C is noted, and the rapid, nonclassical ion heating in RFPs is taken account of. Radial transport parallel to fluctuating magnetic field lines is deemed a likely candidate for both electromagnetic and kinetic energy transport. Two models are discussed and compared. It is concluded that electromagnetic transport using a local Ohm's law best describes nonclassical ion heating, and the transport of kinetic energy by long mean free path electrons best represents the half-Maxwellian of electrons observed in the edge of several RFPs. A nonlocal Ohm's law is essential for the kinetic electron model. 18 refs.

  12. High beta plasma operation in a toroidal plasma producing device

    DOEpatents

    Clarke, John F.

    1978-01-01

    A high beta plasma is produced in a plasma producing device of toroidal configuration by ohmic heating and auxiliary heating. The plasma pressure is continuously monitored and used in a control system to program the current in the poloidal field windings. Throughout the heating process, magnetic flux is conserved inside the plasma and the distortion of the flux surfaces drives a current in the plasma. As a consequence, the total current increases and the poloidal field windings are driven with an equal and opposing increasing current. The spatial distribution of the current in the poloidal field windings is determined by the plasma pressure. Plasma equilibrium is maintained thereby, and high temperature, high beta operation results.

  13. Generation of rotational transform in a toroidal confinement device with tilted coils

    NASA Astrophysics Data System (ADS)

    Zeppetello, Lucas; Doumet, Michel; Hammond, Kenneth; Israeli, Ben; Mann, Justin; Volpe, Francesco; Clark, Anthony; Spong, Donald; Lazerson, Samuel

    2015-11-01

    Experimental evidence was obtained, by means of an electron beam, that rotational transform can be generated in a toroidal configuration constructively similar to a tokamak, but solenoid-free and featuring six tilted toroidal-field coils. The coils are planar and, in fact, circular, hereby the device name CIRCUS. In addition, the coils are interlinked to each other, which helps reducing the aspect ratio but is not strictly required. Comparisons between calculations and field-line mapping measurements will be presented, as well as predictions for devices featuring more coils, resulting in more axisymmetric plasmas. These are expected to operate at lower plasma current than a tokamak of comparable size and magnetic field, which might have interesting implications for disruptions and steady-state operation. Additionally, the toroidal magnetic ripple is less pronounced than in an equivalent tokamak in which the coils are not tilted.

  14. Ambipolar magnetic fluctuation-induced heat transport in toroidal devices

    SciTech Connect

    Terry, P.W.; Fiksel, G.; Ji, H.; Almagri, A.F.; Cekic, M.; Den Hartog, D.J.; Diamond, P.H.; Prager, S.C.; Sarff, J.S.; Shen, W.; Stoneking, M.; Ware, A.S.

    1996-05-01

    The total magnetic fluctuation-induced electron thermal flux has been determined in the Madison Symmetric Torus (MST) reversed-field pinch [Fusion Technol. {bold 19}, 131 (1991)] from the measured correlation of the heat flux along perturbed fields with the radial component of the perturbed field. In the edge region the total flux is convective and intrinsically ambipolar constrained, as evidenced by the magnitude of the thermal diffusivity, which is well approximated by the product of ion thermal velocity and the magnetic diffusivity. A self-consistent theory is formulated and shown to reproduce the experimental results, provided nonlinear charge aggregation in streaming electrons is accounted for in the theory. For general toroidal configurations, it is shown that ambipolar constrained transport applies when remote magnetic fluctuations (i.e., global modes resonant at distant rational surfaces) dominate the flux. Near locations where the dominant modes are resonant, the transport is nonambipolar. This agrees with the radial variation of diffusivity in MST. Expectations for the tokamak are also discussed. {copyright} {ital 1996 American Institute of Physics.}

  15. Air core poloidal magnetic field system for a toroidal plasma producing device

    DOEpatents

    Marcus, Frederick 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.

  16. Dual-function magnetic structure for toroidal plasma devices

    DOEpatents

    Brown, Robert L.

    1978-01-01

    This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring.

  17. Ablation produced using a toroidal high intensity focused ultrasound device is independent of hepatic perfusion

    NASA Astrophysics Data System (ADS)

    Melodelima, David; Dupre, Aurélien; Gandini, Alessandro; Chapelon, Jean-Yves; Rivoire, Michel

    2012-10-01

    In this study an ultrasound device that uses a toroidal HIFU transducer guided by ultrasound imaging was evaluated clinically for the treatment of colorectal liver metastases during an open procedure. Our long-term objective is to associate HIFU with hepatic resection. Here we report the first clinical results obtained on six patients with liver metastases and scheduled for elective surgical resection of their tumors. The principal objective was to validate the effectiveness, tolerance and safety of the HIFU parameters defined during preclinical studies. In addition, the response to HIFU was assessed using the ultrasound imaging probe integrated in the HIFU device and compared directly with histological analysis. Twelve HIFU lesions were performed during hepatectomy. The dimensions measured on ultrasound imaging were correlated (r=0.91) with dimensions measured during histological analysis. The average coagulated dimensions obtained from a single 40s exposure were a diameter of 18.7±2.0 mm and a depth of 27.5±6.3 mm. This HIFU treatment using a toroidal transducer is feasible, safe and well tolerated. This device is capable of achieving selective ablation of predefined liver regions. Ultrasound imaging evidence of complete ablation of the target region can be taken to infer histological success.

  18. Study of plasma equilibrium in toroidal fusion devices using mesh-free numerical calculation method

    NASA Astrophysics Data System (ADS)

    Rasouli, C.; Abbasi Davani, F.; Rokrok, B.

    2016-08-01

    Plasma confinement using external magnetic field is one of the successful ways leading to the controlled nuclear fusion. Development and validation of the solution process for plasma equilibrium in the experimental toroidal fusion devices is the main subject of this work. Solution of the nonlinear 2D stationary problem as posed by the Grad-Shafranov equation gives quantitative information about plasma equilibrium inside the vacuum chamber of hot fusion devices. This study suggests solving plasma equilibrium equation which is essential in toroidal nuclear fusion devices, using a mesh-free method in a condition that the plasma boundary is unknown. The Grad-Shafranov equation has been solved numerically by the point interpolation collocation mesh-free method. Important features of this approach include truly mesh free, simple mathematical relationships between points and acceptable precision in comparison with the parametric results. The calculation process has been done by using the regular and irregular nodal distribution and support domains with different points. The relative error between numerical and analytical solution is discussed for several test examples such as small size Damavand tokamak, ITER-like equilibrium, NSTX-like equilibrium, and typical Spheromak.

  19. Design and construction details of the FRX-C/T device: a compact toroid plasma translation experiment

    SciTech Connect

    Rej, D.J.

    1984-08-01

    The engineering design and construction details for the compact toroid plasma translation experiment FRX-C/T are reviewed. A translation region consisting of a 0.4-m-i.d., up to 6-m-long metallic vacuum chamber has been added onto one end of the field-reversed theta-pinch device FRX-C. A 2.5-MW, dc-powered, water-cooled solenoid magnet produces an axial magnetic field of up to 10 kG in this region. A complete directory of all related engineering drawings is also included.

  20. Shift in principal equilibrium current from a vertical to a toroidal one towards the initiation of a closed flux surface in ECR plasmas in the LATE device

    NASA Astrophysics Data System (ADS)

    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

  1. Resonant magnetic perturbations of edge-plasmas in toroidal confinement devices

    NASA Astrophysics Data System (ADS)

    Evans, T. E.

    2015-12-01

    Controlling the boundary layer in fusion-grade, high-performance, plasma discharges is essential for the successful development of toroidal magnetic confinement power generating systems. A promising approach for controlling the boundary plasma is based on the use of small, externally applied, edge resonant magnetic perturbation (RMP) fields (δ b\\bot\\text{ext}≈ {{10}-4}\\to {{10}-3}~\\text{T} ). A long-term focus area in tokamak fusion research has been to find methods, involving the use of non-axisymmetric magnetic perturbations to reduce the intense particle and heat fluxes to the wall. Experimental RMP research has progressed from the early pioneering work on tokamaks with material limiters in the 1970s, to present day research in separatrix-limited tokamaks operated in high-confinement mode, which is primarily aimed at the mitigation of the intermittent fluxes due edge localized modes (ELMs). At the same time, theoretical research has evolved from analytical models to numerical simulations, including the full 3D complexities of the problem. Following the first demonstration of ELM suppression in the DIII-D tokamak during 2003, there has been a rapid worldwide growth in theoretical, numerical and experimental edge RMP research resulting in the addition of ELM control coils to the ITER baseline design (Loarte et al 2014 Nucl. Fusion 54 033007). This review provides an overview of edge RMP research including a summary of the early theoretical and numerical background along with recent experimental results on improved particle and energy confinement in tokamaks triggered by edge RMP fields. The topics covered make up the basic elements needed for developing a better understanding of 3D magnetic perturbation physics, which is required in order to utilize the full potential of edge RMP fields in fusion relevant high performance, H-mode, plasmas.

  2. CORSICA: A comprehensive simulation of toroidal magnetic-fusion devices. Final report to the LDRD Program

    SciTech Connect

    Crotinger, J.A.; LoDestro, L.; Pearlstein, L.D.; Tarditi, A.; Casper, T.A.; Hooper, E.B.

    1997-03-21

    In 1992, our group began exploring the requirements for a comprehensive simulation code for toroidal magnetic fusion experiments. There were several motivations for taking this step. First, the new machines being designed were much larger and more expensive than current experiments. Second, these new designs called for much more sophisticated control of the plasma shape and position, as well as the distributions of energy, mass, and current within the plasma. These factors alone made it clear that a comprehensive simulation capability would be an extremely valuable tool for machine design. The final motivating factor was that the national Numerical Tokamak Project (NTP) had recently received High Performance Computing and Communications (HPCC) Grand Challenge funding to model turbulent transport in tokamaks, raising the possibility that first-principles simulations of this process might be practical in the near future. We felt that the best way to capitalize on this development was to integrate the resulting turbulence simulation codes into a comprehensive simulation. Such simulations must include the effects of many microscopic length- and time-scales. In order to do a comprehensive simulation efficiently, the length- and time- scale disparities must be exploited. We proposed to do this by coupling the average or quasistatic effects from the fast time-scales to a slow-time-scale transport code for the macroscopic plasma evolution. In FY93-FY96 we received funding to investigate algorithms for computationally coupling such disparate-scale simulations and to implement these algorithms in a prototype simulation code, dubbed CORSICA. Work on algorithms and test cases proceeded in parallel, with the algorithms being incorporated into CORSICA as they became mature. In this report we discuss the methods and algorithms, the CORSICA code, its applications, and our plans for the future.

  3. Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device.

    PubMed

    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. PMID:27250428

  4. Toroidal reactor

    DOEpatents

    Dawson, John M.; Furth, Harold P.; Tenney, Fred H.

    1988-12-06

    Method for producing fusion power wherein a neutral beam is injected into a toroidal bulk plasma to produce fusion reactions during the time permitted by the slowing down of the particles from the injected beam in the bulk plasma.

  5. Toroidal magnet system

    DOEpatents

    Ohkawa, Tihiro; Baker, Charles C.

    1981-01-01

    In a plasma device having a toroidal plasma containment vessel, a toroidal field-generating coil system includes fixed linking coils each formed of first and second sections with the first section passing through a central opening through the containment vessel and the second section completing the linking coil to link the containment vessel. A plurality of removable unlinked coils are each formed of first and second C-shaped sections joined to each other at their open ends with their bights spaced apart. The second C-shaped section of each movable coil is removably mounted adjacent the second section of a linking coil, with the containment vessel disposed between the open ends of the first and second C-shaped sections. Electric current is passed through the linking and removable coils in opposite sense in the respective adjacent second sections to produce a net toroidal field.

  6. Toroidal Nematics

    NASA Astrophysics Data System (ADS)

    Fernandez-Nieves, Alberto

    We will discuss how nematic liquid crystals organize inside toroidal droplets. When the director is parallel to the bounding surface, we find spontaneous reflection symmetry breaking, which we attribute to the role played by saddle-splay contributions to the Frank free energy. When the director is perpendicular to the bounding surface, we find that the structure is reminiscent of the escape radial configuration seen in cylinders, but with a central doubly-twisted organization, which we attribute to the geometry of the torus. We will end by presenting recent experiments with active nematics on the toroidal surface. In this case, topology and activity both affect the structure and dynamics of the material.

  7. On the spatial structure of solitary radial electric field at the plasma edge in toroidal confinement devices

    NASA Astrophysics Data System (ADS)

    Itoh, K.; Itoh, S.-I.; Kamiya, K.; Kasuya, N.

    2015-07-01

    The solitary radial electric field in the edge of toroidal plasma is studied based on the electric field bifurcation model. Results are applied to tokamak and helical plasmas, and the dependence of the electric field structure on the plasma parameters and geometrical factors is analyzed. The order of magnitude estimate for tokamak plasma is not far from experimental observations. It is shown that, in helical plasmas, the height of electric field structure is reduced substantially owing to the ripple particle transport, while the width is influenced less. The implications of the results for the limit of achievable gradient in the H-mode pedestal are also discussed.

  8. RMF concept: a rotating-magnetic-field technique for driving steady plasma currents in compact toroid devices

    SciTech Connect

    McKenna, K.F.

    1980-09-01

    The generation and/or sustaining of a Compact Toroid (CT) configuration using the RMF technique is a relatively new and unknown concept. In this report the basic principles, historical development, and current theoretical understanding of this concept are reviewed. Significant experimental and theoretical results, potential problem areas, and recommendations for the direction of future work are discussed. An illustrative analysis of the application of the RMF technique to a CT reactor is presented. The results of a recent experiment, the Rotamak, in which a Spheromak-like CT plasma was produced using the RMF technique, are presented.

  9. Advanced Toroidal Facility

    SciTech Connect

    Johnson, R.L.

    1985-01-01

    The Advanced Toroidal Facility (ATF) is a new magnetic confinement plasma device under construction at the Oak Ridge National Laboratory (ORNL) that will lead to improvements in toroidal magnetic fusion reactors. The ATF is a type of stellerator, known as a ''torsatron'' which theoretically has the capability to operate at greater than or equal to8% beta in steady state. The ATF plasma has a major radius of 2.1 m, an average minor radius of 0.3 m, and a field of 2 T for a 2 s duration or 1 T steady state. The ATF device consists of a helical field (HF) coil set, a set of poloidal field (PF) coils, an exterior shell structure to support the coils, and a thin, helically contoured vacuum vessel inside the coils. The ATF replaces the Impurities Studies Experiment (ISX-B) tokamak at ORNL and will use the ISX-B auxiliary systems including 4 MW of electron cyclotron heating. The ATF is scheduled to start operation in late 1986. An overview of the ATF device is presented, including details of the construction process envisioned. 9 refs., 7 figs., 3 tabs.

  10. Experimental studies of compact toroids

    SciTech Connect

    Not Available

    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 {mu}s 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.

  11. Toroidal circular dichroism

    NASA Astrophysics Data System (ADS)

    Raybould, T. A.; Fedotov, V. A.; Papasimakis, N.; Kuprov, I.; Youngs, I. J.; Chen, W. T.; Tsai, D. P.; Zheludev, N. I.

    2016-07-01

    We demonstrate that the induced toroidal dipole, represented by currents flowing on the surface of a torus, makes a distinct and indispensable contribution to circular dichroism. We show that toroidal circular dichroism supplements the well-known mechanism involving electric dipole and magnetic dipole transitions. We illustrate this with rigorous analysis of the experimentally measured polarization-sensitive transmission spectra of an artificial metamaterial, constructed from elements of toroidal symmetry. We argue that toroidal circular dichroism will be found in large biomolecules with elements of toroidal symmetry and should be taken into account in the interpretation of circular dichroism spectra of organics.

  12. Shuttleless toroid winder

    DOEpatents

    Lindenmeyer, Carl W.

    1981-01-01

    A lower support receives a toroid at a winding station with the axis of the toroid aligned with a slot in the support. An upper guide member applies an axial force to hold the toroid against the lower support. A pair of movable jaws carried by an indexing mechanism engage the outer surface of the toroid to apply a radial holding force. While the toroid is thus held, a wire is placed axially through the toroid, assisted by a funnel-shaped surface in the upper guide member, and is drawn tight about the toroid by a pair of cooperating draw rollers. When operated in the "full cycle" mode, the operator then actuates a switch which energizes a power drive to release the axial clamp and to drive the indexing mechanism and the jaws to rotate the toroid about its axis. At the same time, the wire is ejected from the draw rollers beneath the toroid so that the operator may grasp it to form another loop. When the toroid is fully indexed, the jaws release it, and the upper guide member is returned to clamp the toroid axially while the indexing mechanism is returned to its starting position. The apparatus may also be operated in a "momentary contact" mode in which the mechanism is driven only for the time a switch is actuated.

  13. Toroidal Lasing Spaser

    PubMed Central

    Huang, Yao-Wei; Chen, Wei Ting; Wu, Pin Chieh; Fedotov, Vassili A.; Zheludev, Nikolay I.; Tsai, Din Ping

    2013-01-01

    Toroidal shapes are often found in bio-molecules, viruses, proteins and fats, but only recently it was proved experimentally that toroidal structures can support exotic high-frequency electromagnetic excitations that are neither electric or magnetic multipoles. Such excitations, known as toroidal moments, could be playing an important role in enhancing inter-molecular interaction and energy transfer due to its higher electromagnetic energy confinement and weaker coupling to free space. Using a model toroidal metamaterial system, we show that coupling optical gain medium with high Q-factor toroidal resonance mode can enhance the single pass amplification to up to 65 dB. This offers an opportunity of creating the “toroidal” lasing spaser, a source of coherent optical radiation that is fueled by toroidal plasmonic oscillations in the nanostructure. PMID:23393619

  14. Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

    SciTech Connect

    Ono, Masayuki.

    1993-05-01

    Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T[sub i] [approx] 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.

  15. Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

    SciTech Connect

    Ono, Masayuki

    1993-05-01

    Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T{sub i} {approx} 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.

  16. Toroid cavity/coil NMR multi-detector

    DOEpatents

    Gerald, II, Rex E.; Meadows, Alexander D.; Gregar, Joseph S.; Rathke, Jerome W.

    2007-09-18

    An analytical device for rapid, non-invasive nuclear magnetic resonance (NMR) spectroscopy of multiple samples using a single spectrometer is provided. A modified toroid cavity/coil detector (TCD), and methods for conducting the simultaneous acquisition of NMR data for multiple samples including a protocol for testing NMR multi-detectors are provided. One embodiment includes a plurality of LC resonant circuits including spatially separated toroid coil inductors, each toroid coil inductor enveloping its corresponding sample volume, and tuned to resonate at a predefined frequency using a variable capacitor. The toroid coil is formed into a loop, where both ends of the toroid coil are brought into coincidence. Another embodiment includes multiple micro Helmholtz coils arranged on a circular perimeter concentric with a central conductor of the toroid cavity.

  17. Invisibility cloaks for toroids.

    PubMed

    You, Yu; Kattawar, George W; Yang, Ping

    2009-04-13

    The material properties of toroidal invisibility cloaks are derived based on the coordinate transformation method. The permittivity and permeability tensors for toroidal cloaks are substantially different from those for spherical cloaks, but quite similar to those for 2D cylindrical cloaks because a singularity is involved at the inner boundary in both the cases. The cloaking effect is confirmed by the electric field distribution in the vicinity of toroidal cloaks simulated from the generalized discrete-dipole approximation (DDA) method. This study extends the concept of electromagnetic cloaking of arbitrarily-shaped objects to a complex geometry. PMID:19365485

  18. Twisted Quantum Toroidal Algebras

    NASA Astrophysics Data System (ADS)

    Jing, Naihuan; Liu, Rongjia

    2014-09-01

    We construct a principally graded quantum loop algebra for the Kac-Moody algebra. As a special case a twisted analog of the quantum toroidal algebra is obtained together with the quantum Serre relations.

  19. Induced toroid structures and toroid polarizabilities

    SciTech Connect

    Costescu, A.; Radescu, E.E.

    1987-06-01

    The frequency-dependent toroid dipole polarizability ..gamma..(..omega..) of a (nonrelativistic, spinless) hydrogenlike atom in its ground state is calculated analytically in terms of two Gauss hypergeometric functions. The static result reads ..gamma..(..omega.. = 0) = (23/60)..cap alpha../sup 2/Z/sup -4/a/sub 0/ /sup 5/(..cap alpha.. = fine-structure constant, Z = nucleus charge number, a/sub 0/ = Bohr radius). Comparing the present evaluations for atoms with previous ones for pions, one sees that the role of the induced toroid moments (as against that of the usual electric ones) increases considerably towards smaller distances (or higher characteristic excitation energies). It might become dramatic at the subhadronic level.

  20. Toroidal core winder

    DOEpatents

    Potthoff, Clifford M.

    1978-01-01

    The disclosure is directed to an apparatus for placing wire windings on a toroidal body, such as a transformer core, having an orifice in its center. The apparatus comprises a wire storage spool, a wire loop holding continuous belt maintained in a C-shaped loop by a belt supporting structure and provision for turning the belt to place and tighten loops of wire on a toroidal body, which is disposed within the gap of the C-shaped belt loop.

  1. NCSX Toroidal Field Coil Design

    SciTech Connect

    Kalish, M.; Rushinski, J.; Myatt, L.; Brooks, A.; Dahlgren, F.; Chrzanowski, J.; Reiersen, W.; Freudenberg, K.

    2005-10-07

    The National Compact Stellarator Experiment (NCSX) is an experimental device whose design and construction is underway at the Department of Energy's Princeton Plasma Physics Laboratory (PPPL). The primary coil systems for the NCSX device consist of the twisted plasma-shaping Modular Coils, the Poloidal Field Coils, and the Toroidal Field (TF) Coils. The TF Coils are D-shaped coils wound from hollow copper conductor, and vacuum impregnated with a glass-epoxy resin system. There are 18 identical, equally spaced TF coils providing 1/R field at the plasma. They operate within a cryostat, and are cooled by LN2, nominally, to 80K. Wedge shaped castings are assembled to the inboard face of these coils, so that inward radial loads are reacted via the nesting of each of the coils against their adjacent partners. This paper outlines the TF Coil design methodology, reviews the analysis results, and summarizes how the design and analysis support the design requirements.

  2. Video Toroid Cavity Imager

    SciTech Connect

    Gerald, Rex E. II; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  3. Third Elementary Dipole Moment: Toroidal

    NASA Astrophysics Data System (ADS)

    Cordrey, Vincent; Eshete, Amanuel; Majewski, Walerian

    2015-04-01

    In this paper we study the generally unknown characteristics of toroids, magnets without magnetic poles. Toroids have never seemed interesting enough to be studied for their physical features in labs due to the fact that they have no magnetic fields on the outside, but rather a very strong magnetic field trapped inside. Toroidal solenoids or magnets (rings magnetized circumferentially) interact with the external magnetic field only through its curl, which can be created either by an electric current, or by a time-dependent electric flux. We confirmed a theoretical prediction, that a toroid would not interact with the curl-less magnetic field of a current-carrying wire running outside of the torus's hole. We used our toroids as magnetic curlmeters, measuring the torque on the toroid, when the current-carrying wire runs through the toroid. From this torque we found the toroidal dipole moment. We are experimenting on detecting the escape of the inner magnetic field of the toroid outside of it, when magnetic toroid rotates or when electric toroid is driven by AC voltage. We also will discuss toroidal (or anapole) moments of fundamental particles, nuclei and atoms, and toroids' applications in metamaterials.

  4. Drift in toroidal configurations

    NASA Astrophysics Data System (ADS)

    Evangelidis, E. A.

    1990-12-01

    This paper considers possible mechanisms involved in amplifying the drift velocity of plasma particles, under conditions of toroidal geometry. It is shown that particles constrained to move on an axisymmetric circular spheroidal surface, develop a sinusoidal motion with a characteristic frequency which depends on the energy of the particles, the value of the isoflux surface, and the value of the general momentum. It is also shown that the incorporation of the effects of toroidal geometry in the Lorentz equation produces a nonambipolar charge-dependent particle flux amplified by a factor 2(q/epsilon) squared.

  5. Progress in Compact Toroid Experiments

    SciTech Connect

    Dolan, Thomas James

    2002-09-01

    The term "compact toroids" as used here means spherical tokamaks, spheromaks, and field reversed configurations, but not reversed field pinches. There are about 17 compact toroid experiments under construction or operating, with approximate parameters listed in Table 1.

  6. Formation of a compact toroid for enhanced efficiency

    SciTech Connect

    Mozgovoy, A. G.; Romadanov, I. V.; Ryzhkov, S. V.

    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.

  7. Formation of a compact toroid for enhanced efficiency

    NASA Astrophysics Data System (ADS)

    Mozgovoy, A. G.; Romadanov, I. V.; Ryzhkov, S. V.

    2014-02-01

    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.

  8. The role of stellarators in the advanced toroidal program

    SciTech Connect

    Sheffield, J.

    1987-01-01

    The goals of this Program as discussed in the DOE-Magnetic Fusion Program Plan and in the Technical Program Activity, have two parts: development of a better understanding of the underlying physics of toroidal devices and the development of the stellarator as a candidate reactor, and as a source of building blocks for other toroidal reactors, such as the tokamak-stellarator hybrid. This paper briefly discusses these concepts. 3 refs.

  9. Inflatable nested toroid structure

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor); Raboin, Jasen L. (Inventor); Spexarth, Gary R. (Inventor)

    2011-01-01

    An inflatable structure comprises at least two generally toroidal, inflatable modules. When in a deployed mode, the first, inner module has a major diameter less than that of a second, outer module and is positioned within the inner circumference of the outer module such that the first module is nested circumferentially alongside the second module. The inflatable structure, in a non-deployed, non-inflated mode, is of compact configuration and adapted to be transported to a site of deployment. When deployed, the inflatable structure is of substantially increased interior volume. In one embodiment, access between the interior of the first module and the second module is provided by at least one port or structural pass-through. In another embodiment, the inflatable structure includes at least one additional generally toroidal module external of and circumferentially surrounding the second module.

  10. Tokamak with liquid metal toroidal field coil

    DOEpatents

    Ohkawa, Tihiro; Schaffer, Michael 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.

  11. Nuclear resonance tomography with a toroid cavity detector

    DOEpatents

    Woelk, K.; Rathke, J.W.; Klingler, R.J.

    1996-11-12

    A toroid cavity detection system is described for determining the spectral properties and distance from a fixed point for a sample using Nuclear Magnetic Resonance. The detection system consists of a toroid with a central conductor oriented along the main axis of the toroidal cylinder and perpendicular to a static uniform magnetic field oriented along the main axis of the toroid. An rf signal is input to the central conductor to produce a magnetic field perpendicular to the central axis of the toroid and whose field strength varies as the inverse of the radius of the toroid. The toroid cavity detection system can be used to encapsulate a sample, or the detection system can be perforated to allow a sample to flow into the detection device or to place the samples in specified sample tubes. The central conductor can also be coated to determine the spectral property of the coating and the coating thickness. The sample is then subjected to the respective magnetic fields and the responses measured to determine the desired properties. 4 figs.

  12. Nuclear resonance tomography with a toroid cavity detector

    DOEpatents

    Woelk, Klaus; Rathke, Jerome W.; Klingler, Robert J.

    1996-01-01

    A toroid cavity detection system for determining the spectral properties and distance from a fixed point for a sample using Nuclear Magnetic Resonance. The detection system consists of a toroid with a central conductor oriented along the main axis of the toroidal cylinder and perpendicular to a static uniform magnetic field oriented along the main axis of the toroid. An rf signal is inputted to the central conductor to produce a magnetic field perpendicular to the central axis of the toroid and whose field strength varies as the inverse of the radius of the toroid. The toroid cavity detection system can be used to encapsulate a sample, or the detection system can be perforated to allow a sample to flow into the detection device or to place the samples in specified sample tubes. The central conductor can also be coated to determine the spectral property of the coating and the coating thickness. The sample is then subjected to the respective magnetic fields and the responses measured to determine the desired properties.

  13. Moment free toroidal magnet

    DOEpatents

    Bonanos, Peter

    1983-01-01

    A toroidal magnet for confining a high magnetic field for use in fusion reactor research and nuclear particle detection. The magnet includes a series of conductor elements arranged about and fixed at its small major radius portion to the outer surface of a central cylindrical support each conductor element having a geometry such as to maintain the conductor elements in pure tension when a high current flows therein, and a support assembly which redistributes all or part of the tension which would otherwise arise in the small major radius portion of each coil element to the large major radius portion thereof.

  14. Equilibrium analysis of tokamak discharges with toroidal variation

    SciTech Connect

    Zwingmann, W.; Becoulet, M.; Moreau, Ph.; Nardon, E.

    2006-11-30

    Tokamaks provide a field structure that is almost axisymmetric around the torus axis. There are however always small toroidal variations due to the limited number of toroidal field coils, the magnetic field ripple. On the other hand, non-axisymmetric external fields are applied on purpose to ergodise the field structure close to the separatrix, to control the heat and particle transport across the plasma boundary. We present a perturbation method to calculate the magnetic field of tokamak discharges with with weak toroidal variation. The method is applied for the equilibrium reconstruction of Tore Supra discharges with toroidal ripple. The perturbation method does not rely on a flux surface representation and can therefore be applied to structures with magnetic islands. We obtain the plasma response to the field of ergodising external coils, as proposed for the ITER device.

  15. Fixed boundary toroidal plasma equilibria with toroidal flows

    NASA Astrophysics Data System (ADS)

    Hu, Yanqiang; Hu, Yemin; Xiang, Nong

    2016-04-01

    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.

  16. Control of impurities in toroidal plasma devices

    DOEpatents

    Ohkawa, Tihiro

    1980-01-01

    A method and apparatus for plasma impurity control in closed flux plasma systems such as Tokamak reactors is disclosed. Local axisymmetrical injection of hydrogen gas is employed to reverse the normally inward flow of impurities into the plasma.

  17. Grinding Inside A Toroidal Cavity

    NASA Technical Reports Server (NTRS)

    Mayer, Walter; Adams, James F.; Burley, Richard K.

    1987-01-01

    Weld lines ground smooth within about 0.001 in. Grinding tool for smoothing longitudinal weld lines inside toroidal cavity includes curved tunnel jig to guide grinding "mouse" along weld line. Curvature of tunnel jig matched to shape of toroid so grinding ball in mouse follows circular arc of correct radius as mouse is pushed along tunnel. Tool enables precise control of grindout shape, yet easy to use.

  18. PEGASUS Toroidal Experimental Facility*

    NASA Astrophysics Data System (ADS)

    Lewicki, B.; Pegasus Group

    1998-11-01

    P EGASUS began operations in June 98 and will study the characteristics of Extremely Low-Aspect Ratio Tokamak (ELART) plasmas. The 2.0m diameter, thin-walled (6.35 mm) vacuum vessel is a continuous stainless steel shell with generous port access. Initial pump down base pressure was 5 × 10-8 torr. The high stress ohmic solenoid is powered by a 15 kV, 4.5 MJ capacitor bank and will be impedance-matched through a 10:1 step-down transformer to extend the pulse length. Operating at peak fields of 13 - 20 T, the solenoid can achieve a flux swing of up to 190mV-s over 60 ms. The toroidal field of 0.1 T on axis is powered by a 3 MVA AC/DC converter capable of 3.5 kA at 600 VDC. The equilibrium and shaping field magnets are powered by 2.2 F of commutated capacitor banks plus a 0.5 MVA programmable switching supply. Modest waveform control is available to compensate for the resistive vacuum vessel and aid in plasma shaping for elongated and diverted plasmas. Operational diagnostics include internal magnetic pickup loops, high resolution and fast framing cameras, and impurity monitoring systems. * *Supported by U.S. DoE grant No. DE-FG02-96ER54375

  19. Effects of Toroidal Rotation Sshear on Toroidicity-induced Alfven Eigenmodes in the National Spherical Torus Experiment

    SciTech Connect

    Podesta, M; Fredrickson, E D; Gorelenkov, N N; LeBlanc, B P; Heidbrink, W W; Crocker, N A; Kubota, S

    2010-08-19

    The effects of a sheared toroidal rotation on the dynamics of bursting Toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40 557 (2000)]. The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of increased damping is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes.

  20. Effects of toroidal rotation shear on toroidicity-induced Alfven eigenmodes in the National Spherical Torus Experiment

    SciTech Connect

    Podesta, M.; Bell, R. E.; Fredrickson, E. D.; Gorelenkov, N. N.; LeBlanc, B. P.; Heidbrink, W. W.; Crocker, N. A.; Kubota, S.; Yuh, H.

    2010-12-15

    The effects of a sheared toroidal rotation on the dynamics of bursting toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)]. The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of decorrelation of the modes by the sheared rotation is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes on NSTX.

  1. Edge ambipolar potential in toroidal fusion plasmasa)

    NASA Astrophysics Data System (ADS)

    Spizzo, G.; Vianello, N.; White, R. B.; Abdullaev, S. S.; Agostini, M.; Cavazzana, R.; Ciaccio, G.; Puiatti, M. E.; Scarin, P.; Schmitz, O.; Spolaore, M.; Terranova, D.

    2014-05-01

    A series of issues with toroidally confined fusion plasmas are related to the generation of 3D flow patterns by means of edge magnetic islands, embedded in a chaotic field and interacting with the wall. These issues include the Greenwald limit in Tokamaks and reversed-field pinches, the collisionality window for ELM mitigation with the resonant magnetic perturbations (RMPs) in Tokamaks, and edge islands interacting with the bootstrap current in stellarators. Measurements of the 2D map of the edge electric field Er(r =a,θ,ϕ) in the RFX reversed-field pinch show that Er has the same helicity of the magnetic islands generated by a m/n perturbation: in fact, defining the helical angle u =mθ-nϕ+ωt, maps show a sinusoidal dependence as a function of u, Er=E ˜rsin u. The associated E × B flow displays a huge convective cell with v(a)≠0 which, in RFX and near the Greenwald limit, determines a stagnation point for density and a reversal of the sign of Er. From a theoretical point of view, the question is how a perturbed toroidal flux of symmetry m/n gives rise to an ambipolar potential Φ =Φ˜sin u. On the basis of a model developed with the guiding center code Orbit and applied to RFX and the TEXTOR tokamak, we will show that the presence of an m/n perturbation in any kind of device breaks the toroidal symmetry with a drift proportional to the gyroradius ρ, thus larger for ions (ρi ≫ ρe). Immediately, an ambipolar potential arises to balance the drifts, with the same symmetry as the original perturbation.

  2. Edge ambipolar potential in toroidal fusion plasmas

    SciTech Connect

    Spizzo, G. Vianello, N.; Agostini, M.; Puiatti, M. E.; Scarin, P.; Spolaore, M.; Terranova, D.; White, R. B.; Abdullaev, S. S.; Schmitz, O.; Cavazzana, R.; Ciaccio, G.

    2014-05-15

    A series of issues with toroidally confined fusion plasmas are related to the generation of 3D flow patterns by means of edge magnetic islands, embedded in a chaotic field and interacting with the wall. These issues include the Greenwald limit in Tokamaks and reversed-field pinches, the collisionality window for ELM mitigation with the resonant magnetic perturbations (RMPs) in Tokamaks, and edge islands interacting with the bootstrap current in stellarators. Measurements of the 2D map of the edge electric field E{sup r}(r=a,θ,ϕ) in the RFX reversed-field pinch show that E{sup r} has the same helicity of the magnetic islands generated by a m/n perturbation: in fact, defining the helical angle u=mθ−nϕ+ωt, maps show a sinusoidal dependence as a function of u, E{sup r}=E{sup ~r}sin u. The associated E × B flow displays a huge convective cell with v(a)≠0 which, in RFX and near the Greenwald limit, determines a stagnation point for density and a reversal of the sign of E{sup r}. From a theoretical point of view, the question is how a perturbed toroidal flux of symmetry m/n gives rise to an ambipolar potential Φ=Φ{sup ~}sin u. On the basis of a model developed with the guiding center code ORBIT and applied to RFX and the TEXTOR tokamak, we will show that the presence of an m/n perturbation in any kind of device breaks the toroidal symmetry with a drift proportional to the gyroradius ρ, thus larger for ions (ρ{sub i} ≫ ρ{sub e}). Immediately, an ambipolar potential arises to balance the drifts, with the same symmetry as the original perturbation.

  3. Experimental studies of compact toroids. Progress report, 1990--1991

    SciTech Connect

    Not Available

    1991-12-01

    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 {mu}s 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.

  4. Concentric Nested Toroidal Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.

    2010-01-01

    Assemblies comprising multiple limited- height toroidal inflatable structures nested in a concentric arrangement have been invented to obtain more design flexibility than can be obtained in single taller, wider toroidal inflatable structures (see figure). Originally intended for use as containers for habitats for humans in outer space or on remote planets, these and related prior inflatable structures could also be useful on Earth as lightweight, compactly stowable, portable special-purpose buildings that could be transported to remote locations and there inflated to full size and shape. In the case of a single inflatable toroidal structure, one important source of lack of design flexibility is the fact that an increase in outer diameter (which is sometimes desired) is necessarily accompanied by an increase in height (which is sometimes undesired). Increases in diameter and height can also cause difficulty in utilization of the resulting larger volume, in that it can become necessary to partition the volume by means of walls and floors, and features (e.g., stairs or ladders) must be added to enable vertical movement between floors. Moreover, ascending and descending between floors in a gravitational environment could pose unacceptable difficulty for the inhabitants under some circumstances. Another source of lack of design flexibility in a single toroidal inflatable structure is that for a given inflation pressure, an increase in the outer diameter of the structure necessarily entails an increase in the maximum stress in the structure. Because it is necessary to keep the maximum stress within the load-bearing capability of the structural materials, consistent with other aspects of the design, this may translate to a limit on the outer diameter. In an assembly comprising concentric nested toroidal structures, an increase in outer diameter does not necessarily entail an increase in height or a maximum stress in excess of the load-bearing capability of the structural

  5. Quantum toroidal moments of nanohelix eigenstates

    NASA Astrophysics Data System (ADS)

    Williamson, Johnny; Encinosa, Mario

    2015-09-01

    Developments in the area of metamaterial research have generated interest in toroidal moments and their treatment in the quantum regime. A quantum mechanical method of determining toroidal moments due to current circulating on a toroidal helix is presented. The Hamiltonian of a negatively charged spinless particle constrained to motion in the vicinity of a toroidal helix having loops of arbitrary eccentricity is developed. The resulting three dimensional Schr¨odinger equation is reduced to a one dimensional form inclusive of curvature effects. Low-lying eigenfunctions of the toroidal helix system are determined along with corresponding toroidal moments. A disagreement, not predicted by a classical treatment, arises between toroidal moments of elliptic toroidal helix systems when vertical and horizontal eccentricity are transposed.

  6. Electrostatic toroidal drift mode turbulence in tokamaks

    SciTech Connect

    Hirshman, S.P.; Diamond, P.H.; Rosenbluth, M.N.; Chen, L.; Molvig, K.; Whitson, J.C.; Smith, J.

    1980-01-01

    The kinetic theory of turbulent effects due to electron orbit stochasticity was combined with linear response in toroidal geometry. A review of the linear theory is given. The toroidal electron response is given in the ballooning representation. (MOW)

  7. An approximate single fluid 3-dimensional magnetohydrodynamic equilibrium model with toroidal flow

    NASA Astrophysics Data System (ADS)

    Cooper, W. A.; Hirshman, S. P.; Chapman, I. T.; Brunetti, D.; Faustin, J. M.; Graves, J. P.; Pfefferlé, D.; Raghunathan, M.; Sauter, O.; Tran, T. M.; Aiba, N.

    2014-09-01

    An approximate model for a single fluid three-dimensional (3D) magnetohydrodynamic (MHD) equilibrium with pure isothermal toroidal flow with imposed nested magnetic flux surfaces is proposed. It recovers the rigorous toroidal rotation equilibrium description in the axisymmetric limit. The approximation is valid under conditions of nearly rigid or vanishing toroidal rotation in regions with significant 3D deformation of the equilibrium flux surfaces. Bifurcated helical core equilibrium simulations of long-lived modes in the MAST device demonstrate that the magnetic structure is only weakly affected by the flow but that the 3D pressure distortion is important. The pressure is displaced away from the major axis and therefore is not as noticeably helically deformed as the toroidal magnetic flux under the subsonic flow conditions measured in the experiment. The model invoked fails to predict any significant screening by toroidal plasma rotation of resonant magnetic perturbations in MAST free boundary computations.

  8. Toroidal Tank Development for Upper-stages

    NASA Technical Reports Server (NTRS)

    DeLay, Tom; Roberts, Keith

    2003-01-01

    The advantages, development, and fabrication of toroidal propellant tanks are profiled in this viewgraph presentation. Several images are included of independent research and development (IR&D) of toroidal propellant tanks at Marshall Space Flight Center (MSFC). Other images in the presentation give a brief overview of Thiokol conformal tank technology development. The presentation describes Thiokol's approach to continuous composite toroidal tank fabrication in detail. Images are shown of continuous and segmented toroidal tanks fabricated by Thiokol.

  9. Particle simulations in toroidal geometry

    SciTech Connect

    Aydemir, A.Y.

    1992-09-01

    A computational tool to be used in kinetic simulations of toroidal plasmas is being developed. The initial goal of the project is to develop an electrostatic gyrokinetic model for studying transport and stability problems in tokamaks. In this brief report, preliminary results from the early stages of this effort are presented.

  10. Fluid interaction with spinning toroidal tanks

    NASA Technical Reports Server (NTRS)

    Fester, D. A.; Anderson, J. E.

    1977-01-01

    An experimental study was conducted to evaluate propellant behavior in spinning torroidal tanks that could be used in a retropropulsion system of an advanced outer-planet Pioneer orbiter. Information on propellant slosh and settling and on ullage orientation and stability was obtained. The effects of axial acceleration, spin rate, spin-rate change, and spacecraft wobble, both singly and in combination, were evaluated using a one-eighth scale transparent tank in one-g and low-g environments. Liquid loadings ranged from 5% to 96% full. The impact of a surface tension acquisition device was assessed by comparison with bare-tank results. The testing simulated the behavior of the fluorine/hydrazine and nitrogen textroxide/monomethylhydrazine propellants. Results are presented that indicate that no major fluid behavior problems would be encountered with any of the four propellants in the toroidal tanks of a spin-stabilized orbiter spacecraft.

  11. Toroid Joining Gun For Fittings And Couplings

    NASA Technical Reports Server (NTRS)

    Fox, Robert L.; Swaim, Robert J.; Johnson, Samuel D.; Buckley, John D.; Copeland, Carl E.; Coultrip, Robert H.; Johnston, David F.; Phillips, William M.

    1992-01-01

    Hand-held gun used to join metal heat-to-shrink couplings. Uses magnetic induction (eddy currents) to produce heat in metal coupling, and thermocouple to measure temperature and signals end of process. Gun, called "toroid joining gun" concentrates high levels of heat in localized areas. Reconfigured for use on metal heat-to-shrink fitting and coupling applications. Provides rapid heating, operates on low power, lightweight and portable. Safe for use around aircraft fuel and has no detrimental effects on surrounding surfaces or objects. Reliable in any environment and under all weather conditions. Gun logical device for taking full advantage of capabilities of new metal heat-to-shrink couplings and fittings.

  12. Experimental tests of a toroidal electrostatic analyzer

    SciTech Connect

    Young, D.T.; Ghielmetti, A.G.; Shelley, E.G.; Marshall, J.A.; Burch, J.L.; Booker, T.L.

    1987-04-01

    A toroidal electrostatic analyzer of a design suitable for space plasma instrumentation has been constructed and tested. Experimental results are compared with second-order ion optical theory and are in good agreement. Verifying the ion optics of the toroid was simplified by use of a position-sensing microchannel-plate detector mounted on a positioning system with three translational degrees of freedom located at the toroid exit. The toroidal analyzer described here is the first optical element in a fully toroidal mass spectrograph intended for analysis of kilovolt magnetospheric plasmas.

  13. Intrinsic rotation of toroidally confined magnetohydrodynamics.

    PubMed

    Morales, Jorge A; Bos, Wouter J T; Schneider, Kai; Montgomery, David C

    2012-10-26

    The spatiotemporal self-organization of viscoresistive magnetohydrodynamics in a toroidal geometry is studied. Curl-free toroidal magnetic and electric fields are imposed. It is observed in our simulations that a flow is generated, which evolves from dominantly poloidal to toroidal when the Lundquist numbers are increased. It is shown that this toroidal organization of the flow is consistent with the tendency of the velocity field to align with the magnetic field. Up-down asymmetry of the geometry causes the generation of a nonzero toroidal angular momentum. PMID:23215195

  14. Electromagnetic effects on toroidal momentum transport

    SciTech Connect

    Mahmood, M. Ansar; Eriksson, A.; Weiland, J.

    2010-12-15

    A parametric study of electromagnetic effects on toroidal momentum transport has been performed. The work is based on a new version of the Weiland model where symmetry breaking toroidicity effects derived from the stress tensor have been taken into account. The model includes a self-consistent calculation of the toroidal momentum diffusivity, which contains both diagonal and off-diagonal contributions to the momentum flux. It is found that electromagnetic effects considerably increase the toroidal momentum pinch. They are sometimes strong enough to make the total toroidal momentum flux inward.

  15. Petascale Parallelization of the Gyrokinetic Toroidal Code

    SciTech Connect

    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.

  16. Hollow nanotubular toroidal polymer microrings

    NASA Astrophysics Data System (ADS)

    Lee, Jiyeong; Baek, Kangkyun; Kim, Myungjin; Yun, Gyeongwon; Ko, Young Ho; Lee, Nam-Suk; Hwang, Ilha; Kim, Jeehong; Natarajan, Ramalingam; Park, Chan Gyung; Sung, Wokyung; Kim, Kimoon

    2014-02-01

    Despite the remarkable progress made in the self-assembly of nano- and microscale architectures with well-defined sizes and shapes, a self-organization-based synthesis of hollow toroids has, so far, proved to be elusive. Here, we report the synthesis of polymer microrings made from rectangular, flat and rigid-core monomers with anisotropically predisposed alkene groups, which are crosslinked with each other by dithiol linkers using thiol-ene photopolymerization. The resulting hollow toroidal structures are shape-persistent and mechanically robust in solution. In addition, their size can be tuned by controlling the initial monomer concentrations, an observation that is supported by a theoretical analysis. These hollow microrings can encapsulate guest molecules in the intratoroidal nanospace, and their peripheries can act as templates for circular arrays of metal nanoparticles.

  17. Prospects for toroidal fusion reactors

    SciTech Connect

    Sheffield, J.; Galambos, J.D.

    1994-06-01

    Work on the International Thermonuclear Experimental Reactor (ITER) tokamak has refined understanding of the realities of a deuterium-tritium (D-T) burning magnetic fusion reactor. An ITER-like tokamak reactor using ITER costs and performance would lead to a cost of electricity (COE) of about 130 mills/kWh. Advanced tokamak physics to be tested in the Toroidal Physics Experiment (TPX), coupled with moderate components in engineering, technology, and unit costs, should lead to a COE comparable with best existing fission systems around 60 mills/kWh. However, a larger unit size, {approximately}2000 MW(e), is favored for the fusion system. Alternative toroidal configurations to the conventional tokamak, such as the stellarator, reversed-field pinch, and field-reversed configuration, offer some potential advantage, but are less well developed, and have their own challenges.

  18. Transport and Dynamics in Toroidal Fusion Systems

    SciTech Connect

    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

  19. Magnetic Properties of 3D Printed Toroids

    NASA Astrophysics Data System (ADS)

    Bollig, Lindsey; Otto, Austin; Hilpisch, Peter; Mowry, Greg; Nelson-Cheeseman, Brittany; Renewable Energy; Alternatives Lab (REAL) Team

    Transformers are ubiquitous in electronics today. Although toroidal geometries perform most efficiently, transformers are traditionally made with rectangular cross-sections due to the lower manufacturing costs. Additive manufacturing techniques (3D printing) can easily achieve toroidal geometries by building up a part through a series of 2D layers. To get strong magnetic properties in a 3D printed transformer, a composite filament is used containing Fe dispersed in a polymer matrix. How the resulting 3D printed toroid responds to a magnetic field depends on two structural factors of the printed 2D layers: fill factor (planar density) and fill pattern. In this work, we investigate how the fill factor and fill pattern affect the magnetic properties of 3D printed toroids. The magnetic properties of the printed toroids are measured by a custom circuit that produces a hysteresis loop for each toroid. Toroids with various fill factors and fill patterns are compared to determine how these two factors can affect the magnetic field the toroid can produce. These 3D printed toroids can be used for numerous applications in order to increase the efficiency of transformers by making it possible for manufacturers to make a toroidal geometry.

  20. Toroidal cell and battery. [Patent application

    SciTech Connect

    Nagle, W.J.

    1981-04-01

    A toroidal storage battery designed to handle relatively high amp-hour loads is described. The cell includes a wound core disposed within a pair of toroidal channel shaped electrodes spaced apart by nylon insulator. The shape of the case electrodes of this toroidal cell allows a first planar doughnut shaped surface and the inner cylindrical case wall to be used as a first electrode and a second planar doughnut shaped surface and the outer cylindrical case wall to be used as a second electrode. Connectors may be used to stack two or more toroidal cells together by connecting substantially the entire surface area of the first electrode of a first cell to substantially the entire surface area of the second electrode of a second cell. The central cavity of each toroidal cell may be used as a conduit for pumping a fluid through the toroidal cell to thereby cool the cell. Official Gazette of the U.S. Patent and Trademark Office

  1. High-frequency electric field measurement using a toroidal antenna

    SciTech Connect

    Lee, K.H.

    1997-01-01

    In this paper the author describes an innovative method of measuring high-frequency electric fields using a toroid. For typical geophysical applications the new sensor will detect electric fields for a wide range of spectrum starting from 1.0 MHz. This window, in particular the lower frequency range between 1.0 to 100 MHz, has not been used for existing electromagnetic or radar systems to detect small objects in the upper few meters of the ground. Ground penetrating radar (GPR) can be used successfully in this depth range if the ground is resistive but most soils are, in fact, conductive (0.01 to 1.0 S/m) rendering GPR inefficient. Other factors controlling the resolution of GPR system for small objects is the spatial averaging inherent in the electric dipole antenna and the scattering caused by soil inhomogeneities of dimensions comparable to the wavelength (and antenna size). For maximum resolution it is desirable to use the highest frequencies but the scattering is large and target identification is poor. Time-varying magnetic fields induce an emf (voltage) in a toroid. The electric field at the center of the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroid one can easily and accurately determine the electric field. The new sensor will greatly simplify the cumbersome procedure involved with GPR measurements with its center frequency less than 100 MHz. The overall size of the toroidal sensor can be as small as a few inches. It is this size advantage that will not only allow easy fabrication and deployment of multi-component devices either on the surface or in a borehole, but it will render greatly improved resolution over conventional systems.

  2. 3D toroidal physics: Testing the boundaries of symmetry breakinga)

    NASA Astrophysics Data System (ADS)

    Spong, Donald A.

    2015-05-01

    Toroidal symmetry is an important concept for plasma confinement; it allows the existence of nested flux surface MHD equilibria and conserved invariants for particle motion. However, perfect symmetry is unachievable in realistic toroidal plasma devices. For example, tokamaks have toroidal ripple due to discrete field coils, optimized stellarators do not achieve exact quasi-symmetry, the plasma itself continually seeks lower energy states through helical 3D deformations, and reactors will likely have non-uniform distributions of ferritic steel near the plasma. Also, some level of designed-in 3D magnetic field structure is now anticipated for most concepts in order to provide the plasma control needed for a stable, steady-state fusion reactor. Such planned 3D field structures can take many forms, ranging from tokamaks with weak 3D edge localized mode suppression fields to stellarators with more dominant 3D field structures. This motivates the development of physics models that are applicable across the full range of 3D devices. Ultimately, the questions of how much symmetry breaking can be tolerated and how to optimize its design must be addressed for all fusion concepts. A closely coupled program of simulation, experimental validation, and design optimization is required to determine what forms and amplitudes of 3D shaping and symmetry breaking will be compatible with the requirements of future fusion reactors.

  3. 3D toroidal physics: Testing the boundaries of symmetry breaking

    SciTech Connect

    Spong, Donald A.

    2015-05-15

    Toroidal symmetry is an important concept for plasma confinement; it allows the existence of nested flux surface MHD equilibria and conserved invariants for particle motion. However, perfect symmetry is unachievable in realistic toroidal plasma devices. For example, tokamaks have toroidal ripple due to discrete field coils, optimized stellarators do not achieve exact quasi-symmetry, the plasma itself continually seeks lower energy states through helical 3D deformations, and reactors will likely have non-uniform distributions of ferritic steel near the plasma. Also, some level of designed-in 3D magnetic field structure is now anticipated for most concepts in order to provide the plasma control needed for a stable, steady-state fusion reactor. Such planned 3D field structures can take many forms, ranging from tokamaks with weak 3D edge localized mode suppression fields to stellarators with more dominant 3D field structures. This motivates the development of physics models that are applicable across the full range of 3D devices. Ultimately, the questions of how much symmetry breaking can be tolerated and how to optimize its design must be addressed for all fusion concepts. A closely coupled program of simulation, experimental validation, and design optimization is required to determine what forms and amplitudes of 3D shaping and symmetry breaking will be compatible with the requirements of future fusion reactors.

  4. Toroidal Theory of MHD Instabilities

    SciTech Connect

    Goedbloed, J.P.

    2004-03-15

    We continue with the adventures of the Alfven wave and its two magnetosonic companions as they travel in the curved space of magnetic surfaces and field lines (Sec. 2), find themselves trapped in singularities of an unprecedented richness (Sec. 3), decide to get themselves better maps of the landscape to do the required twisting while some of their youthful energy is leaking away (Sec. 4), cause trouble at the edge of a powerful empire (Sec. 5), and finally see the light in a distant future (Sec. 6). Needed on the trip are the evolution equations of both ideal and resistive MHD 'derived' in reference [1], the solutions to the toroidal equilibrium equations discussed in reference [2], the general background on spectral theory of inhomogeneous plasmas presented in reference [3], which is extended in the two directions of toroidal geometry and resistivity in this lecture [4]. This leads to such intricate dynamics that numerical techniques are virtually the only way to proceed. This aspect is further elaborated in reference [5] on numerical techniques.

  5. ARIES-ACT1 Safety Design and Analysis

    SciTech Connect

    Humrickhouse, Paul W.; Merrill, Brad J.

    2014-01-01

    ARIES-ACT1 (Advanced and Conservative Tokamak) is a 1000-MW(electric) tokamak design featuring advanced plasma physics and divertor and blanket engineering. Some relevant features include an advanced SiC blanket with PbLi as coolant and breeder; a helium-cooled steel structural ring and tungsten divertors; a thin-walled, helium-cooled vacuum vessel; and a room-temperature, water-cooled shield outside the vacuum vessel. We consider here some safety aspects of the ARIES-ACT1 design and model a series of design-basis and beyond-design-basis accidents with the MELCOR code modified for fusion. The presence of multiple coolants (PbLi, helium, and water) makes possible a variety of such accidents. We consider here a loss-of-flow accident caused by a long-term station blackout (LTSBO), an ex-vessel helium break into the cryostat, and a beyond-design-basis accident in which a LTSBO is aggravated by a loss-of-coolant accident in ARIES-ACT1's ultimate decay heat removal system, the water-cooled shield. In the design-basis accidents, we find that the secondary confinement boundaries are not challenged, and the structural integrity of in-vessel components is not threatened by high temperatures or pressures; decay heat can be passively removed.

  6. Toroidal current asymmetry in tokamak disruptions

    SciTech Connect

    Strauss, H. R.

    2014-10-15

    It was discovered on JET that disruptions were accompanied by toroidal asymmetry of the toroidal plasma current I{sub ϕ}. It was found that the toroidal current asymmetry was proportional to the vertical current moment asymmetry with positive sign for an upward vertical displacement event (VDE) and negative sign for a downward VDE. It was observed that greater displacement leads to greater measured I{sub ϕ} asymmetry. Here, it is shown that this is essentially a kinematic effect produced by a VDE interacting with three dimensional MHD perturbations. The relation of toroidal current asymmetry and vertical current moment is calculated analytically and is verified by numerical simulations. It is shown analytically that the toroidal variation of the toroidal plasma current is accompanied by an equal and opposite variation of the toroidal current flowing in a thin wall surrounding the plasma. These currents are connected by 3D halo current, which is π/2 radians out of phase with the n = 1 toroidal current variations.

  7. Toroidal Alfven wave stability in ignited tokamaks

    SciTech Connect

    Cheng, C.Z.; Fu, G.Y.; Van Dam, J.W.

    1989-01-01

    The effects of fusion-product alpha particles on the stability of global-type shear Alfven waves in an ignited tokamak plasma are investigated in toroidal geometry. Finite toroidicity can lead to stabilization of the global Alfven eigenmodes, but it induces a new global shear Alfven eigenmodes, which is strongly destabilized via transit resonance with alpha particles. 8 refs., 2 figs.

  8. Electrostatics of a Family of Conducting Toroids

    ERIC Educational Resources Information Center

    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…

  9. Cutoff frequency of toroidal plasma waveguide

    SciTech Connect

    Zakeri-Khatir, H.; Aghamir, F. M.

    2015-02-15

    The cutoff frequencies of E and H-modes of empty and plasma filled toroidal waveguides are evaluated. The effects of space curvature and plasma density on cutoff frequencies for both modes are investigated. Using a suitable variable change, a scalar wave equation in the direction of propagation was obtained. The study indicates that the curvature in the direction of wave propagation in toroidal waveguide has an analogous effect as a straight waveguide filled with anisotropic media. The Rayleigh-Schrodinger perturbation method was employed to solve for cutoff frequencies in the first order of approximation. In the limit of small space curvature, the toroidal waveguide cutoff frequencies for both E and H-modes approach those of TM and TE modes of empty cylindrical waveguide with a radius equal to toroidal waveguide minor radius. The analysis shows that the curvature in the direction of propagation in toroidal waveguides leads to the removal of the degeneracy between E and H-modes.

  10. Asymmetric Magnon Excitation by Spontaneous Toroidal Ordering

    NASA Astrophysics Data System (ADS)

    Hayami, Satoru; Kusunose, Hiroaki; Motome, Yukitoshi

    2016-05-01

    The effects of spontaneous toroidal ordering on magnetic excitation are theoretically investigated for a localized spin model that includes a staggered Dzyaloshinsky-Moriya interaction and anisotropic exchange interactions, which arise from the antisymmetric spin-orbit coupling and the multiorbital correlation effect. We show that the model exhibits a Néel-type antiferromagnetic order, which simultaneously accompanies a ferroic toroidal order. We find that the occurrence of toroidal order modulates the magnon dispersion in an asymmetric way with respect to the wave number: a toroidal dipole order on the zigzag chain leads to a band-bottom shift, while a toroidal octupole order on the honeycomb lattice gives rise to a valley splitting. These asymmetric magnon excitations could be a source of unusual magnetic responses, such as nonreciprocal magnon transport. A variety of modulations are discussed while changing the lattice and magnetic symmetries. The implications regarding candidate materials for asymmetric magnon excitations are presented.

  11. Development of Toroidal Core Transformers

    SciTech Connect

    Leon, Francisco

    2014-05-31

    The original objective of this project was to design, build and test a few prototypes of singlephase 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

  12. Tokamak with mechanical compression of toroidal magnetic field

    DOEpatents

    Ohkawa, Tihiro

    1981-01-01

    A tokamak apparatus includes a pressure vessel for defining a reservoir and confining liquid therein. A collapsible toroidal liner disposed within the pressure vessel defines a toroidal space within the liner. Liquid metal fills the reservoir outside said liner. A toroidal magnetic field is developed within the toroidal space about the major axis thereof. A toroidal plasma is developed within the toroidal space about the major axis thereof. Pressure is applied to the liquid metal to collapse the liner and reduce the volume of the toroidal space, thereby increasing the toroidal magnetic flux density therein.

  13. Ballooning mode spectrum in general toroidal systems

    SciTech Connect

    Dewar, R.L.; Glasser, A.H.

    1982-04-01

    A WKB formalism for constructing normal modes of short-wavelength ideal hydromagnetic, pressure-driven instabilities (ballooning modes) in general toroidal magnetic containment devices with sheared magnetic fields is developed. No incompressibility approximation is made. A dispersion relation is obtained from the eigenvalues of a fourth order system of ordinary differential equations to be solved by integrating along a line of force. Higher order calculations are performed to find the amplitude equation and the phase change at a caustic. These conform to typical WKB results. In axisymmetric systems, the ray equations are integrable, and semiclassical quantization leads to a growth rate spectrum consisting of an infinity of discrete eigenvalues, bounded above by an accumulation point. However, each eigenvalue is infinitely degenerate. In the nonaxisymmetric case, the rays are unbounded in a four dimensional phase space, and semiclassical quantization breaks down, leading to broadening of the discrete eigenvalues and accumulation point of the axisymmetric case into continuum bands. Analysis of a model problem indicates that the broadening of the discrete eigenvalues is numerically very small, the dominant effect being broadening of the accumulation point.

  14. Sawtooth Instability in the Compact Toroidal Hybrid

    NASA Astrophysics Data System (ADS)

    Herfindal, J. L.; Maurer, D. A.; Hartwell, G. J.; Ennis, D. A.; Knowlton, S. F.

    2015-11-01

    Sawtooth instabilities have been observed in the Compact Toroidal Hybrid (CTH), a current-carrying stellarator/tokamak hybrid device. The sawtooth instability is driven by ohmic heating of the core plasma until the safety factor drops below unity resulting in the growth of an m = 1 kink-tearing mode. Experiments varying the vacuum rotational transform from 0.02 to 0.13 are being conducted to study sawtooth property dependance on vacuum flux surface structure. The frequency of the sawtooth oscillations increase from 2 kHz to 2.8 kHz solely due the decrease in rise time of the oscillation, the crash time is unchanged. CTH has three two-color SXR cameras, a three-channel 1mm interferometer, and a new bolometer system capable of detecting the signatures of sawtooth instabilities. The new bolometer system consists of two cameras, each containing a pair of diode arrays viewing the plasma directly or through a beryllium filter. Electron temperature measurements are found with the two-color SXR cameras through a ratio of the SXR intensities. Impurity radiation can drastically affect the electron temperature measurement, therefore new filters consisting of aluminum and carbon were selected to avoid problematic line radiation while maximizing the signal for a 100 eV plasma. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

  15. Effects of neoclassical toroidal viscosity induced by the intrinsic error fields and toroidal field ripple on the toroidal rotation in tokamaks

    NASA Astrophysics Data System (ADS)

    Lee, H. H.; Seol, J.; Ko, W. H.; Terzolo, L.; Aydemir, A. Y.; In, Y.; Ghim, Y.-c.; Lee, S. G.

    2016-08-01

    Effects of neoclassical toroidal viscosity (NTV) induced by intrinsic error fields and toroidal field ripple on cocurrent toroidal rotation in H-mode tokamak plasmas are investigated. It is expected that large NTV torque can be localized at the edge region through the 1/ν-regime in the vicinity of E r ˜ 0 in the cocurrent rotating H-mode plasma. Numerical simulation on toroidal rotation demonstrates that the edge localized NTV torque determined by the intrinsic error fields and toroidal field ripples in the level of most tokamaks can damp the toroidal rotation velocity over the whole region while reducing the toroidal rotation pedestal which is clearly observed in Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It is found that the NTV torque changes the toroidal rotation gradient in the pedestal region dramatically, but the toroidal rotation profile in the core region responds rigidly without a change in the gradient. On the other hand, it shows that the NTV torque induced by the intrinsic error fields and toroidal field ripple in the level of the KSTAR tokamak, which are expected to be smaller than most tokamaks by at least one order of magnitude, is negligible in determining the toroidal rotation velocity profile. Experimental observation on the toroidal rotation change by the externally applied nonaxisymmetric magnetic fields on KSTAR also suggests that NTV torque arising from nonaxisymmetric magnetic fields can damp the toroidal rotation over the whole region while diminishing the toroidal rotation pedestal.

  16. Tokamak with in situ magnetohydrodynamic generation of toroidal magnetic field

    DOEpatents

    Schaffer, Michael J.

    1986-01-01

    A tokamak apparatus includes an electrically conductive metal pressure vessel for defining a chamber and confining liquid therein. A liner disposed within said chamber defines a toroidal space within the liner and confines gas therein. The metal vessel provides an electrically conductive path linking the toroidal space. Liquid metal is forced outwardly through the chamber outside of the toroidal space to generate electric current in the conductive path and thereby generate a toroidal magnetic field within the toroidal space. Toroidal plasma is developed within the toroidal space about the major axis thereof.

  17. Steady state compact toroidal plasma production

    DOEpatents

    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.

  18. Bow-shaped toroidal field coils

    SciTech Connect

    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.

  19. Quantum fields in toroidal topology

    SciTech Connect

    Khanna, F.C.; Malbouisson, A.P.C.; Santana, A.E.

    2011-10-15

    The standard representation of c*-algebra is used to describe fields in compactified space-time dimensions characterized by topologies of the type {Gamma}{sub D}{sup d}=(S{sup 1}){sup d}xM{sup D-d}. The modular operator is generalized to introduce representations of isometry groups. The Poincare symmetry is analyzed and then we construct the modular representation by using linear transformations in the field modes, similar to the Bogoliubov transformation. This provides a mechanism for compactification of the Minkowski space-time, which follows as a generalization of the Fourier integral representation of the propagator at finite temperature. An important result is that the 2x2 representation of the real-time formalism is not needed. The end result on calculating observables is described as a condensate in the ground state. We initially analyze the free Klein-Gordon and Dirac fields, and then formulate non-abelian gauge theories in {Gamma}{sub D}{sup d}. Using the S-matrix, the decay of particles is calculated in order to show the effect of the compactification. - Highlights: > C*-algebra is used to describe fields in compactified space-time dimensions. > The space-time is characterized by toroidal topologies. > Representations of the Poincare group are studied by using the modular operator. > We derive non-abelian gauge theories in compactified regions of space-time. > We show the compactification effect in the decay of particles using the S-matrix.

  20. Low-n shear Alfven spectra in axisymmetric toroidal plasmas

    SciTech Connect

    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.

  1. Viscous damping of toroidal angular momentum in tokamaks

    SciTech Connect

    Stacey, W. M.

    2014-09-15

    The Braginskii viscous stress tensor formalism was generalized to accommodate non-axisymmetric 3D magnetic fields in general toroidal flux surface geometry in order to provide a representation for the viscous damping of toroidal rotation in tokamaks arising from various “neoclassical toroidal viscosity” mechanisms. In the process, it was verified that the parallel viscosity contribution to damping toroidal angular momentum still vanishes even in the presence of toroidal asymmetries, unless there are 3D radial magnetic fields.

  2. The differential regulation of human ACT1 isoforms by Hsp90 in IL-17 signaling1

    PubMed Central

    Wu, Ling; Wang, Chenhui; Boisson, Bertrand; Misra, Saurav; Rayman, Patricia; Finke, James H.; Puel, Anne; Casanova, Jean-Laurent; Li, Xiaoxia

    2014-01-01

    IL-17 is a pro-inflammatory cytokine implicated in the pathogenesis of autoimmune diseases including psoriasis. ACT1 is an essential adaptor molecule in the IL-17 signaling pathway. A missense single nucleotide polymorphism (rs33980500; SNP-D10N) that resulted in the substitution of an asparagine for an aspartic acid at position 10 of ACT1 (ACT1-D10N) is associated with psoriasis susceptibility. Due to alternative splicing in humans, SNP-D10N encodes two mutated ACT1 proteins, ACT1-D10N and ACT1-D19N. Though both ACT1 isoforms are Hsp90 ‘client’ proteins, the nine additional amino acids in ACT1-D19N provide an additional Hsp90 binding site that is absent in ACT1-D10N. Therefore, while ACT1-D10N is a dead protein that is unable to transduce IL-17 signals for gene expression, ACT1-D19N is fully responsive to IL-17. Intriguingly, the two ACT1 isoforms are differentially expressed in ACT1D10N/D10N fibroblasts and T cells. Fibroblasts express both isoforms equally, enabling ACT1-D19N to compensate for the loss of ACT1-D10N function. ACT1D10N/D10N T cells, however, express predominantly ACT1-D10N. Lacking this compensatory mechanism, ACT1D10N/D10N T cells behave like ACT1-deficient T cells, exhibiting a dysregulated and hyperactive Th17 phenotype with overproduction of IL-22 and IL-17. The hyperactive Th17 response combined with fully responsive fibroblasts likely synergized to contribute to psoriasis susceptibility in SNP-D10N patients. PMID:25024377

  3. The differential regulation of human ACT1 isoforms by Hsp90 in IL-17 signaling.

    PubMed

    Wu, Ling; Wang, Chenhui; Boisson, Bertrand; Misra, Saurav; Rayman, Patricia; Finke, James H; Puel, Anne; Casanova, Jean-Laurent; Li, Xiaoxia

    2014-08-15

    IL-17 is a proinflammatory cytokine implicated in the pathogenesis of autoimmune diseases including psoriasis. ACT1 is an essential adaptor molecule in the IL-17 signaling pathway. A missense single nucleotide polymorphism (rs33980500; SNP-D10N) that resulted in the substitution of an asparagine for an aspartic acid at position 10 of ACT1 (ACT1-D10N) is associated with psoriasis susceptibility. Due to alternative splicing in humans, SNP-D10N encodes two mutated ACT1 proteins, ACT1-D10N and ACT1-D19N. Although both ACT1 isoforms are Hsp90 client proteins, the nine additional amino acids in ACT1-D19N provide an additional Hsp90 binding site that is absent in ACT1-D10N. Therefore, whereas ACT1-D10N is a dead protein that is unable to transduce IL-17 signals for gene expression, ACT1-D19N is fully responsive to IL-17. Intriguingly, the two ACT1 isoforms are differentially expressed in ACT1(D10N/D10N) fibroblasts and T cells. Fibroblasts express both isoforms equally, enabling ACT1-D19N to compensate for the loss of ACT1-D10N function. ACT1(D10N/D10N) T cells, however, express predominantly ACT1-D10N. Lacking this compensatory mechanism, ACT1(D10N/D10N) T cells behave like ACT1-deficient T cells, exhibiting a dysregulated and hyperactive Th17 phenotype with overproduction of IL-22 and IL-17. The hyperactive Th17 response combined with fully responsive fibroblasts likely synergized to contribute to psoriasis susceptibility in SNP-D10N patients. PMID:25024377

  4. Hamiltonian guiding center drift orbit calculation for toroidal plasmas of arbitrary cross section

    SciTech Connect

    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.

  5. Determination of broken KAM surfaces for particle orbits in toroidal confinement systems

    DOE PAGESBeta

    White, R. B.

    2015-10-05

    Here, the destruction of Kolmogorov–Arnold–Moser surfaces in a Hamiltonian system is an important topic in nonlinear dynamics, and in particular in the theory of particle orbits in toroidal magnetic confinement systems. Analytic models for transport due to mode-particle resonances are not sufficiently correct to give the effect of these resonances on transport. In this paper we compare three different methods for the detection of the loss of stability of orbits in the dynamics of charged particles in a toroidal magnetic confinement device in the presence of time dependent magnetic perturbations.

  6. A feasibility study of developing toroidal tanks for a spinning spacecraft

    NASA Technical Reports Server (NTRS)

    Anderson, J. E.; Fester, D. A.

    1973-01-01

    A study was made to determine the feasibility of developing toroidal propellant tanks for a bipropellant (N204/MMH) propulsion system to be used in a proposed advanced Pioneer spin-stabilized vehicle intended for a Jupiter-orbiter and possibly a Saturn-orbiter mission. The rationale for considering the use of two toroidal tanks rather than the proposed use of four spherical tanks includes the belief that a more symmetrical distribution of propellant mass and a smaller variation in the position of the vehicle center-of-mass during propellant consumption would result, reducing requirements for attitude-control propellants, for balance weight, and for other weights associated with the dynamics of the spinning spacecraft. Results lead to the conclusion that a toroidal tank containing an effective, passive surface tension propellant acquisition device could be fabricated with available manufacturing methods and could be used interchangeably for either fuel or oxidizer.

  7. Dual-band toroidal-dipole-induced transparency in optical regime

    NASA Astrophysics Data System (ADS)

    Li, Jie; Dong, Zheng-Gao; Zhu, Ming-Jie; Shao, Jian; Wang, Ying-Hua; Li, Jia-Qi

    2016-09-01

    The interference between toroidal and electric dipoles in the optical regime is investigated in a metallic composite metastructure composed of a 12-fold double-bar and an upright rod. It shows that toroidal and electric dipoles can be simultaneously excited, exhibiting a plasmon analog of electromagnetically induced transparency (EIT) and suppressing the far-field radiation. By shifting the upright rod transversally, another transparency window emerges due to the asymmetry of the geometry, resulting in dual-band EIT-like behavior. The result not only contributes to the understanding of optical toroidal dipoles, but also creates the possibility of designing optical devices based on the dual-band EIT-like effect.

  8. Impact of the background toroidal rotation on particle and heat turbulent transport in tokamak plasmas

    SciTech Connect

    Camenen, Y.; Peeters, A. G.; Casson, F. J.; Hornsby, W. A.; Snodin, A. P.; Angioni, C.; Strintzi, D.

    2009-01-15

    Recent developments in the gyrokinetic theory have shown that, in a toroidal device, the Coriolis drift associated with the background plasma rotation significantly affects the small scale instabilities [A. G. Peeters et al., Phys. Rev. Lett. 98, 265003 (2007)]. The later study, which focuses on the effect of the Coriolis drift on toroidal momentum transport is extended in the present paper to heat and particle transport. It is shown numerically using the gyrokinetic flux-tube code GKW[A. G. Peeters and D. Strintzi, Phys. Plasmas 11, 3748 (2004)], and supported analytically, that the Coriolis drift and the parallel dynamics play a similar role in the coupling of density, temperature, and velocity perturbations. The effect on particle and heat fluxes increases with the toroidal rotation (directly) and with the toroidal rotation gradient (through the parallel mode structure), depends on the direction of propagation of the perturbation, increases with the impurity charge number and with the impurity mass to charge number ratio. The case of very high toroidal rotation, relevant to spherical tokamaks, is investigated by including the effect of the centrifugal force in a fluid model. The main effect of the centrifugal force is to decrease the local density gradient at the low field side midplane and to add an extra contribution to the fluxes. The conditions for which the inertial terms significantly affect the heat and particle fluxes are evidenced.

  9. Long-wavelength microinstabilities in toroidal plasmas

    SciTech Connect

    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,[theta]) 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.

  10. Long-wavelength microinstabilities in toroidal plasmas

    SciTech Connect

    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,{theta}) 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.

  11. Tokamak with liquid metal for inducing toroidal electrical field

    DOEpatents

    Ohkawa, Tihiro

    1981-01-01

    A tokamak apparatus includes a vessel for defining a reservoir and confining liquid therein. A toroidal liner disposed within said vessel defines a toroidal space within the liner confines gas therein. Liquid metal fills the reservoir outside the liner. A magnetic field is established in the liquid metal to develop magnetic flux linking the toroidal space. The gas is ionized. The liquid metal and the toroidal space are moved relative to one another transversely of the space to generate electric current in the ionized gas in the toroidal space about its major axis and thereby heat plasma developed in the toroidal space.

  12. Quasisymmetric toroidal plasmas with large mean flows

    SciTech Connect

    Sugama, H.; Watanabe, T.-H.; Nunami, M.; Nishimura, S.

    2011-08-15

    Geometric conditions for quasisymmetric toroidal plasmas with large mean flows on the order of the ion thermal speed are investigated. Equilibrium momentum balance equations including the inertia term due to the large flow velocity are used to show that, for rotating quasisymmetric plasmas with no local currents crossing flux surfaces, all components of the metric tensor should be independent of the toroidal angle in the Boozer coordinates, and consequently these systems need to be rigorously axisymmetric. Unless the local radial currents vanish, the Boozer coordinates do not exist and the toroidal flow velocity cannot take any value other than a very limited class of eigenvalues corresponding to very rapid rotation especially for low beta plasmas.

  13. Ferroic nature of magnetic toroidal order.

    PubMed

    Zimmermann, Anne S; Meier, Dennis; Fiebig, Manfred

    2014-01-01

    Electric dipoles and ferroelectricity violate spatial inversion symmetry, and magnetic dipoles and ferromagnetism break time-inversion symmetry. Breaking both symmetries favours magnetoelectric charge-spin coupling effects of enormous interest, such as multiferroics, skyrmions, polar superconductors, topological insulators or dynamic phenomena such as electromagnons. Extending the rationale, a novel type of ferroic order violating space- and time-inversion symmetry with a single order parameter should exist. This existence is fundamental and the inherent magnetoelectric coupling is technologically interesting. A uniform alignment of magnetic vortices, called ferrotoroidicity, was proposed to represent this state. Here we demonstrate that the magnetic vortex pattern identified in LiCoPO4 exhibits the indispensable hallmark of such a ferroic state, namely hysteretic poling of ferrotoroidic domains in the conjugate toroidal field, along with a distinction of toroidal from non-toroidal poling effects. This consolidates ferrotoroidicity as fourth form of ferroic order. PMID:25190207

  14. Toroidal Precession as a Geometric Phase

    SciTech Connect

    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.

  15. The effect of sheared toroidal rotation on pressure driven magnetic islands in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Hegna, C. C.

    2016-05-01

    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.

  16. Electromagnetic toroidal excitations in matter and free space

    NASA Astrophysics Data System (ADS)

    Papasimakis, N.; Fedotov, V. A.; Savinov, V.; Raybould, T. A.; Zheludev, N. I.

    2016-03-01

    The toroidal dipole is a localized electromagnetic excitation, distinct from the magnetic and electric dipoles. While the electric dipole can be understood as a pair of opposite charges and the magnetic dipole as a current loop, the toroidal dipole corresponds to currents flowing on the surface of a torus. Toroidal dipoles provide physically significant contributions to the basic characteristics of matter including absorption, dispersion and optical activity. Toroidal excitations also exist in free space as spatially and temporally localized electromagnetic pulses propagating at the speed of light and interacting with matter. We review recent experimental observations of resonant toroidal dipole excitations in metamaterials and the discovery of anapoles, non-radiating charge-current configurations involving toroidal dipoles. While certain fundamental and practical aspects of toroidal electrodynamics remain open for the moment, we envision that exploitation of toroidal excitations can have important implications for the fields of photonics, sensing, energy and information.

  17. Electromagnetic toroidal excitations in matter and free space.

    PubMed

    Papasimakis, N; Fedotov, V A; Savinov, V; Raybould, T A; Zheludev, N I

    2016-03-01

    The toroidal dipole is a localized electromagnetic excitation, distinct from the magnetic and electric dipoles. While the electric dipole can be understood as a pair of opposite charges and the magnetic dipole as a current loop, the toroidal dipole corresponds to currents flowing on the surface of a torus. Toroidal dipoles provide physically significant contributions to the basic characteristics of matter including absorption, dispersion and optical activity. Toroidal excitations also exist in free space as spatially and temporally localized electromagnetic pulses propagating at the speed of light and interacting with matter. We review recent experimental observations of resonant toroidal dipole excitations in metamaterials and the discovery of anapoles, non-radiating charge-current configurations involving toroidal dipoles. While certain fundamental and practical aspects of toroidal electrodynamics remain open for the moment, we envision that exploitation of toroidal excitations can have important implications for the fields of photonics, sensing, energy and information. PMID:26906961

  18. Method and apparatus to produce and maintain a thick, flowing, liquid lithium first wall for toroidal magnetic confinement DT fusion reactors

    DOEpatents

    Woolley, Robert D.

    2002-01-01

    A system for forming a thick flowing liquid metal, in this case lithium, layer on the inside wall of a toroid containing the plasma of a deuterium-tritium fusion reactor. The presence of the liquid metal layer or first wall serves to prevent neutron damage to the walls of the toroid. A poloidal current in the liquid metal layer is oriented so that it flows in the same direction as the current in a series of external magnets used to confine the plasma. This current alignment results in the liquid metal being forced against the wall of the toroid. After the liquid metal exits the toroid it is pumped to a heat extraction and power conversion device prior to being reentering the toroid.

  19. Startup Studies and Initial Operations of the PEGASUS Toroidal Experiment*

    NASA Astrophysics Data System (ADS)

    Thorson, T.; Dannhausen, D.; Fonck, R.; Intrator, T.; Lewicki, B.; Sontag, A.; Tritz, K.; Wilson, C.

    1998-11-01

    Optimization of ohmic flux consumption is an issue for present day spherical toroidal experiments (ST's) due to the relatively small amount of volt-seconds available for devices running at low aspect ratio (A). This is especially true for P EGASUS (A ~ 1.1), where presently up to 60 kW of electron cyclotron resonance (ECR) preionization (at 5.5 GHz) along with ohmic induction are used for plasma initiation. Available startup optimization techniques include varying the timing and strength of the inductive voltage, the fields from the internal coils for null formation, and the external vertical field during the plasma current ramp-up phase. Since impurity radiation can be a large power loss during startup, wall conditioning techniques, including He glow discharge cleaning and boronization, will also be used to improve startup efficiency and overall plasma performance. Initial operations of P EGASUS focus on exploring the Extremely Low Aspect Ratio Tokamak (ELART) regime of operation (A < 1.2) with low toroidal field (< 0.1 T on axis). * *Supported by U.S. DoE grant No. DE-FG02-96ER54375

  20. Compact Toroidal Hybrid Research Program: Recent Progress and Future Plans

    NASA Astrophysics Data System (ADS)

    Maurer, D. A.; Cianciosa, M.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Knowlton, S. F.; Archmiller, M. C.; Traverso, P.; Pandya, M.; Ma, X.

    2012-10-01

    Understanding the control and avoidance of major disruptions in current carrying toroidal plasmas is important in mitigating the effects of rapid loss of confinement in future devices. The Compact Toroidal Hybrid (CTH) experiment is investigating the passive avoidance of disruptions with the addition of a small amount of vacuum transform provided by external coils. In ohmically-driven stellarator plasmas no disruptions of any kind are observed if the vacuum transform exceeds ˜ 0.11. Recent progress on the suppression of low-qa (high a), density limit, and vertically unstable plasma disruptions is overviewed. Interpretation of these results makes use of 3D equilibrium reconstructions using the V3FIT code [1]. Several new diagnostic tools have recently been developed and implemented on CTH. These new research tools include multi-chord interferometry, bolometry, Hα emission detection, a two-color soft x-ray camera, and upgraded magnetic sensor arrays. In addition to these diagnostic improvements, a new 200 kW gyrotron system will provide additional heating power for stellarator target plasmas. Future research directions and plans will also be discussed. [4pt] [1] J. D. Hanson, S. P. Hirshman, S. F. Knowlton, L. L. Lao, E. A. Lazarus, J. M. Shields, Nucl. Fusion, 49 (2009) 075031

  1. Toroidal angular momentum transport with non-axisymmetric magnetic fields

    NASA Astrophysics Data System (ADS)

    Seol, J.; Park, B. H.

    2016-05-01

    In this study, we calculate the radial transport of the toroidal angular momentum in the presence of non-axisymmetric magnetic fields. It is shown that the radial transport of the toroidal angular momentum, R 2 ∇ ζ . V , is proportional to the first order of gyro-radius. This implies that the neoclassical toroidal viscosity caused by asymmetric magnetic fields can change the toroidal rotation significantly.

  2. Toroidal Alfven eigenmode-induced ripple trapping

    SciTech Connect

    White, R.B.; Fredrickson, E.; Darrow, D.; Zarnstorff, M.; Wilson, R.; Zweben, S.; Hill, K.; Chen, Y.; Fu, G.

    1995-08-01

    Toroidal Alfven eigenmodes are shown to be capable of inducing ripple trapping of high-energy particles in tokamaks, causing intense localized particle loss. The effect has been observed in TFTR [R. Hawryluk, Plasma Phys. Controlled Fusion {bold 33}, 1509 (1991)]. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  3. PULSAR WIND NEBULAE WITH THICK TOROIDAL STRUCTURE

    SciTech Connect

    Chevalier, Roger A.; Reynolds, Stephen P. E-mail: reynolds@ncsu.edu

    2011-10-10

    We investigate a class of pulsar wind nebulae that show synchrotron emission from a thick toroidal structure. The best studied such object is the small radio and X-ray nebula around the Vela pulsar, which can be interpreted as the result of interaction of a mildly supersonic inward flow with the recent pulsar wind. Such a flow near the center of a supernova remnant can be produced in a transient phase when the reverse shock reaches the center of the remnant. Other nebulae with a thick toroidal structure are G106.6+2.9 and G76.9+1.0. Their structure contrasts with young pulsar nebulae like the Crab Nebula and 3C 38, which show a more chaotic, filamentary structure in the synchrotron emission. In both situations, a torus-jet structure is present where the pulsar wind passes through a termination shock, indicating the flow is initially toroidal. We suggest that the difference is due to the Rayleigh-Taylor instability that operates when the outer boundary of the nebula is accelerating into freely expanding supernova ejecta. The instability gives rise to mixing in the Crab and related objects, but is not present in the nebulae with thick toroidal regions.

  4. Dynamical model for the toroidal sporadic meteors

    SciTech Connect

    Pokorný, Petr; Vokrouhlický, David; Nesvorný, David; Campbell-Brown, Margaret; Brown, Peter E-mail: vokrouhl@cesnet.cz E-mail: margaret.campbell@uwo.ca

    2014-07-01

    More than a decade of radar operations by the Canadian Meteor Orbit Radar have allowed both young and moderately old streams to be distinguished from the dispersed sporadic background component. The latter has been categorized according to broad radiant regions visible to Earth-based observers into three broad classes: the helion and anti-helion source, the north and south apex sources, and the north and south toroidal sources (and a related arc structure). The first two are populated mainly by dust released from Jupiter-family comets and new comets. Proper modeling of the toroidal sources has not to date been accomplished. Here, we develop a steady-state model for the toroidal source of the sporadic meteoroid complex, compare our model with the available radar measurements, and investigate a contribution of dust particles from our model to the whole population of sporadic meteoroids. We find that the long-term stable part of the toroidal particles is mainly fed by dust released by Halley type (long period) comets (HTCs). Our synthetic model reproduces most of the observed features of the toroidal particles, including the most troublesome low-eccentricity component, which is due to a combination of two effects: particles' ability to decouple from Jupiter and circularize by the Poynting-Robertson effect, and large collision probability for orbits similar to that of the Earth. Our calibrated model also allows us to estimate the total mass of the HTC-released dust in space and check the flux necessary to maintain the cloud in a steady state.

  5. Toroid Joining Gun. [thermoplastic welding system using induction heating

    NASA Technical Reports Server (NTRS)

    Buckley, J. D.; Fox, R. L.; Swaim, R J.

    1985-01-01

    The Toroid Joining Gun is a low cost, self-contained, portable low powered (100-400 watts) thermoplastic welding system developed at Langley Research Center for joining plastic and composite parts using an induction heating technique. The device developed for use in the fabrication of large space sructures (LSST Program) can be used in any atmosphere or in a vacuum. Components can be joined in situ, whether on earth or on a space platform. The expanded application of this welding gun is in the joining of thermoplastic composites, thermosetting composites, metals, and combinations of these materials. Its low-power requirements, light weight, rapid response, low cost, portability, and effective joining make it a candidate for solving many varied and unique bonding tasks.

  6. Capillary toroid cavity detector for high pressure NMR

    SciTech Connect

    Gerald, II, Rex E.; Chen, Michael J.; Klingler, Robert J.; Rathke, Jerome W.; ter Horst, Marc

    2007-09-11

    A Toroid Cavity Detector (TCD) is provided for implementing nuclear magnetic resonance (NMR) studies of chemical reactions under conditions of high pressures and temperatures. A toroid cavity contains an elongated central conductor extending within the toroid cavity. The toroid cavity and central conductor generate an RF magnetic field for NMR analysis. A flow-through capillary sample container is located within the toroid cavity adjacent to the central conductor to subject a sample material flowing through the capillary to a static magnetic field and to enable NMR spectra to be recorded of the material in the capillary under a temperature and high pressure environment.

  7. Toroidal modeling of penetration of the resonant magnetic perturbation field

    SciTech Connect

    Liu Yueqiang; Kirk, A.

    2013-04-15

    A toroidal, quasi-linear model is proposed to study the penetration dynamics of the resonant magnetic perturbation (RMP) field into the plasma. The model couples the linear, fluid plasma response to a toroidal momentum balance equation, which includes torques induced by both fluid electromagnetic force and by (kinetic) neoclassical toroidal viscous (NTV) force. The numerical results for a test toroidal equilibrium quantify the effects of various physical parameters on the field penetration and on the plasma rotation braking. The neoclassical toroidal viscous torque plays a dominant role in certain region of the plasma, for the RMP penetration problem considered in this work.

  8. Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods

    NASA Astrophysics Data System (ADS)

    Watson, Derek W.; Jenkins, Stewart D.; Ruostekoski, Janne; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2016-03-01

    We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration—a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and appears as a Fano resonance dip in the forward scattered light. We provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.

  9. The Segmented Bifilar Contrawound Toroidal Helical Antenna.

    NASA Astrophysics Data System (ADS)

    Vanvoorhies, Kurt Louis

    The segmented bifilar contrawound toroidal helical antenna, a.k.a. QuadContra antenna creates a toroidal magnetic current whose radiated electromagnetic fields emulate those of an electric dipole located normal to the plane of the toroidal helix. This antenna is a magnetic dual of the constant current electric loop antenna. Its principal advantages of reduced size and low profile result from both its circular geometry and from the velocity factor of its slow wave contrawound helical structure. This antenna is constructed by winding two conductors in contrawound relation to each other on a toroidal form, dividing the winding into an even number of segments, and reversing the pitch sense of each conductor from one segment to another. Feed ports are located on the conductors at the segment boundaries, and are connected in alternate phase to a central signal terminal via balanced and tuned transmission line elements. At resonance, each winding segment supports a quarter-wave sinusoidal current distribution. Toroidal electric current components are canceled, and poloidal current components are enhanced in the resulting anti-symmetric mode current distribution. This study measured and simulated the velocity factor, input impedance, bandwidth and simulated the radiation gain and pattern for a variety of linear and toroidal structures. The velocity factor, modeled as a power function of the ratio of axial winding length to wire length, was two to three times slower for the anti-symmetric mode contrawound helix than for a comparable monofilar helix. The radiation characteristics of the antenna were simulated using the OSU ESP4 Moment Method based program, after making extensive improvements to accommodate a wide variety of antenna configurations and to automatically find resonant frequencies. The simulated QuadContra antenna radiates with vertically polarization in a dipole-like pattern having a gain about 2 dB less than the dipole. The gain falls off dramatically for

  10. High-beta spherical tokamak startup in TS-4 merging experiment by use of toroidal field ramp-up

    NASA Astrophysics Data System (ADS)

    Kaminou, Yasuhiro; , Toru, II; Kato, Joji; Inomoto, Michiaki; Ono, Yasushi; TS Group Team; National InstituteFusion Science Collaboration

    2014-10-01

    We demonstrated the formation method of an ultrahigh-beta spherical tokamak by use of a field-reversed configuration and a spheromak in TS-4 device (R ~ 0.5 m, A ~ 1.5, Ip ~ 30-100 kA, B ~ 100 mT). This method is composed of the following steps: 1. Two spheromaks are merged together and a high-beta spheromak or FRC is formed by reconnection heating. 2. External toroidal magnetic field is added (current rising time ~50 μs), and spherical tokamak-like configuration is formed. In this way, the ultrahigh-beta ST is formed. The ultrahigh-beta ST formed by FRC has a diamagnetic toroidal field, and it presumed to be in a second-stable state for ballooning stability, and the one formed by spheromak has a weak paramagnetic toroidal magnetic field, while a spheormak has a strong paramagnetic toroidal magnetic field. This diamagnetic current derives from inductive electric field by ramping up the external toroidal magnetic field, and the diamagnetic current sustains high thermal pressure of the ultrahigh-beta spherical tokamak. And the beta of the ultrahigh-beta ST formed by FRC reaches about 50%. To sustain the high-beta state, 0.6 MW neutral beam injection and center solenoid coils are installed to the TS-4 device. In the poster, we report the experimental results of ultrahigh-beta spherical tokamak startup and sustainment by NBI and CS current driving experiment.

  11. Use of a miniature Toroidal Grating Monochromator on the FEL Undulator at the NSLS

    SciTech Connect

    Johnson, P.D.; Hulbert, S.L.; Howells, M.R.

    1984-01-01

    The use of a miniature Toroidal Grating Monochromator is described which we intend to use to monochromatize the radiation from the free electron laser (FEL) Undulator at the NSLS. Some of the properties of Undulators are described with reference to the design of beamlines and review the properties of TGM's. The results of ray tracing a beamline using such a device and estimates of the expected flux are given.

  12. Diffusiophoresis of a charged toroidal polyelectrolyte.

    PubMed

    Tseng, Shiojenn; Hsu, Yen-Rei; Hsu, Jyh-Ping

    2016-06-01

    Considering recent application of concentration driven motion of charged nanoparticles in sensing technology, we model the diffusiophoresis of an isolated toroidal polyelectrolyte (PE) for the first time. Choosing an aqueous KCl solution for illustration, its behavior under various conditions is simulated by varying the double layer thickness, the size of toroid, and its softness and fixed charge density. We show that the behavior of the present PE can be different both quantitatively and qualitatively from that of the corresponding spherical PE. This arises from the competition of the hydrodynamic force and the electric force acting on a PE. The geometry and the nature of a PE can also influence appreciably its behavior, yielding complicated and interesting results. PMID:26970033

  13. Plasmonic Toroidal Metamolecules Assembled by DNA Origami.

    PubMed

    Urban, Maximilian J; Dutta, Palash K; Wang, Pengfei; Duan, Xiaoyang; Shen, Xibo; Ding, Baoquan; Ke, Yonggang; Liu, Na

    2016-05-01

    We show hierarchical assembly of plasmonic toroidal metamolecules that exhibit tailored optical activity in the visible spectral range. Each metamolecule consists of four identical origami-templated helical building blocks. Such toroidal metamolecules show a stronger chiroptical response than monomers and dimers of the helical building blocks. Enantiomers of the plasmonic structures yield opposite circular dichroism spectra. Experimental results agree well with the theoretical simulations. We also show that given the circular symmetry of the structures s distinct chiroptical response along their axial orientation can be uncovered via simple spin-coating of the metamolecules on substrates. Our work provides a new strategy to create plasmonic chiral platforms with sophisticated nanoscale architectures for potential applications such as chiral sensing using chemically based assembly systems. PMID:27082140

  14. Solar Dynamo and Toroidal Field Instabilities

    NASA Astrophysics Data System (ADS)

    Bonanno, Alfio

    2013-10-01

    The possibility of non-axisymmetric (kink) instabilities of a toroidal field seated in the tachocline is much discussed in the literature. In this work, the basic properties of kink and quasi-interchange instabilities, produced by mixed toroidal and poloidal configuration, will be briefly reviewed. In particular, it will be shown that the unstable modes are strongly localized near the Equator and not near the Poles as often claimed in the literature. Based on the results of recent numerical simulations, it is argued that a non-zero helicity can already be produced at a non-linear level. A mean-field solar dynamo is then constructed with a positive α-effect in the overshoot layer localized near the Equator, and a meridional circulation with deep return flow. Finally, the possibility that the solar cycle is driven by an αΩ dynamo generated by the negative subsurface shear in the supergranulation layer will also be discussed.

  15. Solar concentrator with a toroidal relay module.

    PubMed

    Lin, Jhe-Syuan; Liang, Chao-Wen

    2015-10-01

    III-V multijunction solar cells require solar concentrators with a high concentration ratio to reduce per watt cost and to increase solar energy transforming efficiency. This paper discusses a novel solar concentrator design that features a high concentration ratio, high transfer efficiency, thin profile design, and a high solar acceptance angle. The optical design of the concentrator utilizes a toroidal relay module, which includes both the off-axis relay lens and field lens design in a single concentric toroidal lens shape. The optical design concept of the concentrator is discussed and the simulation results are shown. The given exemplary design has an aspect ratio of 0.24, a high averaged optical concentration ratio 1230×, a maximum efficiency of 76.8%, and the solar acceptance angle of ±0.9°. PMID:26479646

  16. Defect unbinding on a toroidal nematic shell.

    PubMed

    Jesenek, Dalija; Kralj, Samo; Rosso, Riccardo; Virga, Epifanio G

    2015-03-28

    We study nematic liquid crystal textures exhibiting topological defects (TDs) on a two-dimensional (2D) toroidal shell. For the toroidal topology the total topological charge of TDs is equal to zero. We use a mesoscopic Landau-de Gennes approach which features a 2D nematic order tensor Q. We show that fat tori unbind TDs. If no extrinsic free energy couples Q with the Weingarten tensor of the torus, then defects and antidefects are assembled along the innermost and the outermost circles of the torus, respectively. In this case, we estimate the critical condition for the onset of TDs using an electrostatic analogy. If, on the other hand, an extrinsic free energy is present, then defects are repelled from these regions. PMID:25662487

  17. Magnetohydrodynamic stability of structurally stable toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Rock, F. C.

    1981-11-01

    The MHD stability of sharp boundary axisymmetric toroidal plasmas with the poloidal field and 'kidney bean' shape implied by the requirements of structural stability (immunity of the magnetic field topology to small perturbations) is investigated. High values of marginal beta (up to 36 percent for R/a = 2) are found. Results are presented for the four magnetic field topologies on the sharp boundary surface with this shape and as a function of elongation.

  18. Muon dynamics in a toroidal sector magnet

    SciTech Connect

    Gallardo, J.C.; Fernow, R.; Palmer, R.B.

    1997-09-17

    The present scenario for the cooling channel in a high brightness muon collider calls for a quasi-continuous solenoidal focusing channel. The beam line consists of a periodic array of rf cavities and approximately 2 cm long LiH absorbers immersed in a solenoid with alternating focusing field (FOFO). The authors present a Hamiltonian formulation of muon dynamics in toroidal sector solenoids (bent solenoid).

  19. Neoclassical transport in enhanced confinement toroidal plasmas

    SciTech Connect

    Lin, Z.; Tang, W.M.; Lee, W.W.

    1996-11-01

    It has recently been reported that ion thermal transport levels in enhanced confinement tokamak plasmas have been observed to fall below the irreducible minimum level predicted by standard neoclassical theory. This apparent contradiction is resolved in the present analysis by relaxing the basic neoclassical assumption that the ions orbital excursions are much smaller than the local toroidal minor radius and the equilibrium scale lengths of the system.

  20. Toroidal Dipole Moment of a Massless Neutrino

    SciTech Connect

    Cabral-Rosetti, L. G.; Mondragon, M.; Perez, E. Reyes

    2009-04-20

    We obtain the toroidal dipole moment of a massless neutrino {tau}{sub v{sub I}}{sup M} using the results for the anapole moment of a massless Dirac neutrino a{sub v{sub I}}{sup D}, which was obtained in the context of the Standard Model of the electroweak interactions (SM)SU(2){sub L} x U(1){sub Y}.

  1. Superconducting toroidal field coil current densities for the TFCX

    SciTech Connect

    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/sup 2/ with 10-T peak field at the winding and peak nuclear heat load limits of 1 MW/cm/sup 3/ for the nominal design and 50 MW/cm/sup 3/ for an advanced design. This study developed justification for these current density and nuclear heat load limits.

  2. Finite toroidal flow generated by unstable tearing mode in a toroidal plasma

    SciTech Connect

    Hao, G. Z. Wang, A. K.; Xu, Y. H.; He, H. D.; Xu, M.; Qu, H. P.; Peng, X. D.; Xu, J. Q.; Qiu, X. M.; Liu, Y. Q.; Sun, Y.; Cui, S. Y.

    2014-12-15

    The neoclassical toroidal plasma viscosity torque and electromagnetic torque, generated by tearing mode (TM) in a toroidal plasma, are numerically investigated using the MARS-Q code [Liu et al., Phys. Plasmas 20, 042503 (2013)]. It is found that an initially unstable tearing mode can intrinsically drive a toroidal plasma flow resulting in a steady state solution, in the absence of the external momentum input and external magnetic field perturbation. The saturated flow is in the order of 0.5%ω{sub A} at the q=2 rational surface in the considered case, with q and ω{sub A} being the safety factor and the Alfven frequency at the magnetic axis, respectively. The generation of the toroidal flow is robust, being insensitive to the given amplitude of the perturbation at initial state. On the other hand, the flow amplitude increases with increasing the plasma resistivity. Furthermore, the initially unstable tearing mode is fully stabilized by non-linear interaction with the self-generated toroidal flow.

  3. Superconducting magnets for toroidal fusion reactors

    SciTech Connect

    Haubenreich, P.N.

    1980-01-01

    Fusion reactors will soon be employing superconducting magnets to confine plasma in which deuterium and tritium (D-T) are fused to produce usable energy. At present there is one small confinement experiment with superconducting toroidal field (TF) coils: Tokamak 7 (T-7), in the USSR, which operates at 4 T. By 1983, six different 2.5 x 3.5-m D-shaped coils from six manufacturers in four countries will be assembled in a toroidal array in the Large Coil Test Facility (LCTF) at Oak Ridge National Laboratory (ORNL) for testing at fields up to 8 T. Soon afterwards ELMO Bumpy Torus (EBT-P) will begin operation at Oak Ridge with superconducting TF coils. At the same time there will be tokamaks with superconducting TF coils 2 to 3 m in diameter in the USSR and France. Toroidal field strength in these machines will range from 6 to 9 T. NbTi and Nb/sub 3/Sn, bath cooling and forced flow, cryostable and metastable - various designs are being tried in this period when this new application of superconductivity is growing and maturing.

  4. Toroidal rotation and halo current produced by disruptions

    NASA Astrophysics Data System (ADS)

    Strauss, Henry; Sugiyama, Linda; Paccagnella, Roberto; Breslau, Joshua; Jardin, Stephen

    2013-10-01

    In several experiments including JET, it was observed that disruptions were accompanied by toroidal rotation. There is a concern that there may be a resonance between rotating toroidal perturbations and the resonant frequencies of the ITER vacuum vessel, causing enhanced damage. MHD simulations with M3D demonstrate that disruptions produce toroidal rotation. The toroidal velocity can produce several rotations of the sideways force during a disruption. Edge localized modes (ELMs) also produce poloidal and toroidal rotation. A theory of rotation produced by MHD activity will be presented. In the case of ELMs, the theory gives toroidal rotation Alfven Mach number, Mϕ ~10-2βN . This is consistent with a scaling for intrinsic toroidal rotation in H mode tokamaks. It was also discovered on JET that disruptions were accompanied by toroidal variation of the plasma current Iϕ. From ∇ . j = 0 , the toroidal current variation ΔIϕ is proportional to the 3D halo current, ∮Jn Rdl , where Jn is the normal current density at the wall. The 3D halo current is calculated analytically and computationally. A bound on ΔIϕ /Iϕ is found, proportional to the halo current fraction and toroidal peaking factor. Supported by USDOE and ITER.

  5. 3D toroidal physics: testing the boundaries of symmetry breaking

    NASA Astrophysics Data System (ADS)

    Spong, Don

    2014-10-01

    Toroidal symmetry is an important concept for plasma confinement; it allows the existence of nested flux surface MHD equilibria and conserved invariants for particle motion. However, perfect symmetry is unachievable in realistic toroidal plasma devices. For example, tokamaks have toroidal ripple due to discrete field coils, optimized stellarators do not achieve exact quasi-symmetry, the plasma itself continually seeks lower energy states through helical 3D deformations, and reactors will likely have non-uniform distributions of ferritic steel near the plasma. Also, some level of designed-in 3D magnetic field structure is now anticipated for most concepts in order to lead to a stable, steady-state fusion reactor. Such planned 3D field structures can take many forms, ranging from tokamaks with weak 3D ELM-suppression fields to stellarators with more dominant 3D field structures. There is considerable interest in the development of unified physics models for the full range of 3D effects. Ultimately, the questions of how much symmetry breaking can be tolerated and how to optimize its design must be addressed for all fusion concepts. Fortunately, significant progress is underway in theory, computation and plasma diagnostics on many issues such as magnetic surface quality, plasma screening vs. amplification of 3D perturbations, 3D transport, influence on edge pedestal structures, MHD stability effects, modification of fast ion-driven instabilities, prediction of energetic particle heat loads on plasma-facing materials, effects of 3D fields on turbulence, and magnetic coil design. A closely coupled program of simulation, experimental validation, and design optimization is required to determine what forms and amplitudes of 3D shaping and symmetry breaking will be compatible with future fusion reactors. The development of models to address 3D physics and progress in these areas will be described. This work is supported both by the US Department of Energy under Contract DE

  6. Analysis of rice Act1 5' region activity in transgenic rice plants.

    PubMed Central

    Zhang, W; McElroy, D; Wu, R

    1991-01-01

    The 5' region of the rice actin 1 gene (Act1) has been developed as an efficient regulator of foreign gene expression in transgenic rice plants. To determine the pattern and level of rice Act1 5' region activity, transgenic rice plants containing the Act1 5' region fused to a bacterial beta-glucuronidase (Gus) coding sequence were generated. Two independent clonal lines of transgenic rice plants were analyzed in detail. Quantitative analysis showed that tissue from these transgenic rice plants have a level of GUS protein that represents as much as 3% of total soluble protein. We were able to demonstrate that Act1-Gus gene expression is constitutive throughout the sporophytic and gametophytic tissues of these transgenic rice plants. Plants from one transgenic line were analyzed for the segregation of GUS activity in pollen by in situ histochemical staining, and the inheritance and stability of Act1-Gus expression were assayed in subsequently derived progeny plants. PMID:1821763

  7. Parametric design studies of toroidal magnetic energy storage units

    NASA Astrophysics Data System (ADS)

    Herring, J. Stephen

    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 was 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. Designs are presented 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 were divided into modules suitable for normal truck or rail transport.

  8. Landau damping of geodesic acoustic mode in toroidally rotating tokamaks

    SciTech Connect

    Ren, Haijun; Cao, Jintao

    2015-06-15

    Geodesic acoustic mode (GAM) is analyzed by using modified gyro-kinetic (MGK) equation applicable to low-frequency microinstabilities in a rotating axisymmetric plasma. Dispersion relation of GAM in the presence of arbitrary toroidal Mach number is analytically derived. The effects of toroidal rotation on the GAM frequency and damping rate do not depend on the orientation of equilibrium flow. It is shown that the toroidal Mach number M increases the GAM frequency and dramatically decreases the Landau damping rate.

  9. Toroidal magnetic detector for high resolution measurement of muon momenta

    DOEpatents

    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.

  10. Toroidal magnetic detector for high resolution measurement of muon momenta

    DOEpatents

    Bonanos, P.

    1992-01-07

    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. 4 figs.

  11. The effect of toroidicity on reversed field pinch dynamics

    NASA Astrophysics Data System (ADS)

    Morales, Jorge A.; Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.

    2014-09-01

    The influence of the curvature of the imposed magnetic field on reversed field pinch dynamics is investigated by comparing the flow of a magnetofluid in a torus with aspect ratio 1.83, with the flow in a periodic cylinder. It is found that an axisymmetric toroidal mode is always present in the toroidal, but absent in the cylindrical configuration. In particular, in contrast to the cylinder, the toroidal case presents a double poloidal recirculation cell with a shear localized at the plasma edge. Quasi-single-helicity states are found to be more persistent in toroidal than in periodic cylinder geometry.

  12. Berry phases and zero-modes in toroidal topological insulator

    NASA Astrophysics Data System (ADS)

    Fonseca, Jakson M.; Carvalho-Santos, Vagson L.; Moura-Melo, Winder A.; Pereira, Afranio R.

    2016-06-01

    An effective Hamiltonian describing the surface states of a toroidal topological insulator is obtained, and it is shown to support both bound-states and charged zero-modes. Actually, the spin connection induced by the toroidal curvature can be viewed as an position-dependent effective vector potential, which ultimately yields the zero-modes whose wave-functions harmonically oscillate around the toroidal surface. In addition, two distinct Berry phases are predicted to take place by the virtue of the toroidal topology.

  13. Physics basis for an advanced physics and advanced technology tokamak power plant configuration: ARIES-ACT1

    SciTech Connect

    Kessel, C. E.; Poli, F. M.; Ghantous, K.; Gorelenkov, N. N.; Rensink, M. E.; Rognlien, T. D.; Snyder, P. B.; St. John, H.; Turnbull, A. D.

    2015-01-01

    Here, the advanced physics and advanced technology tokamak power plant ARIES-ACT1 has a major radius of 6.25 m at an aspect ratio of 4.0, toroidal field of 6.0 T, strong shaping with elongation of 2.2, and triangularity of 0.63. The broadest pressure cases reached wall-stabilized βN ~ 5.75, limited by n = 3 external kink mode requiring a conducting shell at b/a = 0.3, requiring plasma rotation, feedback, and/or kinetic stabilization. The medium pressure peaking case reaches βN = 5.28 with BT = 6.75, while the peaked pressure case reaches βN < 5.15. Fast particle magnetohydrodynamic stability shows that the alpha particles are unstable, but this leads to redistribution to larger minor radius rather than loss from the plasma. Edge and divertor plasma modeling shows that 75% of the power to the divertor can be radiated with an ITER-like divertor geometry, while >95% can be radiated in a stable detached mode with an orthogonal target and wide slot geometry. The bootstrap current fraction is 91% with a q95 of 4.5, requiring ~1.1 MA of external current drive. This current is supplied with 5 MW of ion cyclotron radio frequency/fast wave and 40 MW of lower hybrid current drive. Electron cyclotron is most effective for safety factor control over ρ~0.2 to 0.6 with 20 MW. The pedestal density is ~0.9×1020/m3, and the temperature is ~4.4 keV. The H98 factor is 1.65, n/nGr = 1.0, and the ratio of net power to threshold power is 2.8 to 3.0 in the flattop.

  14. Physics basis for an advanced physics and advanced technology tokamak power plant configuration: ARIES-ACT1

    DOE PAGESBeta

    Kessel, C. E.; Poli, F. M.; Ghantous, K.; Gorelenkov, N. N.; Rensink, M. E.; Rognlien, T. D.; Snyder, P. B.; St. John, H.; Turnbull, A. D.

    2015-01-01

    Here, the advanced physics and advanced technology tokamak power plant ARIES-ACT1 has a major radius of 6.25 m at an aspect ratio of 4.0, toroidal field of 6.0 T, strong shaping with elongation of 2.2, and triangularity of 0.63. The broadest pressure cases reached wall-stabilized βN ~ 5.75, limited by n = 3 external kink mode requiring a conducting shell at b/a = 0.3, requiring plasma rotation, feedback, and/or kinetic stabilization. The medium pressure peaking case reaches βN = 5.28 with BT = 6.75, while the peaked pressure case reaches βN < 5.15. Fast particle magnetohydrodynamic stability shows that themore » alpha particles are unstable, but this leads to redistribution to larger minor radius rather than loss from the plasma. Edge and divertor plasma modeling shows that 75% of the power to the divertor can be radiated with an ITER-like divertor geometry, while >95% can be radiated in a stable detached mode with an orthogonal target and wide slot geometry. The bootstrap current fraction is 91% with a q95 of 4.5, requiring ~1.1 MA of external current drive. This current is supplied with 5 MW of ion cyclotron radio frequency/fast wave and 40 MW of lower hybrid current drive. Electron cyclotron is most effective for safety factor control over ρ~0.2 to 0.6 with 20 MW. The pedestal density is ~0.9×1020/m3, and the temperature is ~4.4 keV. The H98 factor is 1.65, n/nGr = 1.0, and the ratio of net power to threshold power is 2.8 to 3.0 in the flattop.« less

  15. The Physics Basis For An Advanced Physics And Advanced Technology Tokamak Power Plant Configuration, ARIES-ACT1

    SciTech Connect

    Charles Kessel, et al

    2014-03-05

    The advanced physics and advanced technology tokamak power plant ARIES-ACT1 has a major radius of 6.25 m at aspect ratio of 4.0, toroidal field of 6.0 T, strong shaping with elongation of 2.2 and triangularity of 0.63. The broadest pressure cases reached wall stabilized βN ~ 5.75, limited by n=3 external kink mode requiring a conducting shell at b/a = 0.3, and requiring plasma rotation, feedback, and or kinetic stabilization. The medium pressure peaking case reached βN = 5.28 with BT = 6.75, while the peaked pressure case reaches βN < 5.15. Fast particle MHD stability shows that the alpha particles are unstable, but this leads to redistribution to larger minor radius rather than loss from the plasma. Edge and divertor plasma modeling show that about 75% of the power to the divertor can be radiated with an ITER-like divertor geometry, while over 95% can be radiated in a stable detached mode with an orthogonal target and wide slot geometry. The bootstrap current fraction is 91% with a q95 of 4.5, requiring about ~ 1.1 MA of external current drive. This current is supplied with 5 MW of ICRF/FW and 40 MW of LHCD. EC was examined and is most effective for safety factor control over ρ ~ 0.2-0.6 with 20 MW. The pedestal density is ~ 0.9x1020 /m3 and the temperature is ~ 4.4 keV. The H98 factor is 1.65, n/nGr = 1.0, and the net power to LH threshold power is 2.8- 3.0 in the flattop.

  16. Toroidal plasma enhanced CVD of diamond films

    SciTech Connect

    Zvanya, John Cullen, Christopher Morris, Thomas Krchnavek, Robert R.; Holber, William Basnett, Andrew Basnett, Robert; Hettinger, Jeffrey

    2014-09-01

    An inductively coupled toroidal plasma source is used as an alternative to microwave plasmas for chemical vapor deposition of diamond films. The source, operating at a frequency of 400 kHz, synthesizes diamond films from a mixture of argon, methane, and hydrogen. The toroidal design has been adapted to create a highly efficient environment for diamond film deposition: high gas temperature and a short distance from the sample to the plasma core. Using a toroidal plasma geometry operating in the medium frequency band allows for efficient (≈90%) coupling of AC line power to the plasma and a scalable path to high-power and large-area operation. In test runs, the source generates a high flux of atomic hydrogen over a large area, which is favorable for diamond film growth. Using a deposition temperature of 900–1050 °C and a source to sample distance of 0.1–2.0 cm, diamond films are deposited onto silicon substrates. The results showed that the deposition rate of the diamond films could be controlled using the sample temperature and source to sample spacing. The results also show the films exhibit good-quality polycrystalline diamond as verified by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. The scanning electron microscopy and x-ray diffraction results show that the samples exhibit diamond (111) and diamond (022) crystallites. The Raman results show that the sp{sup 3} peak has a narrow spectral width (FWHM 12 ± 0.5 cm{sup −1}) and that negligible amounts of the sp{sup 2} band are present, indicating good-quality diamond films.

  17. Toroidal membrane vesicles in spherical confinement.

    PubMed

    Bouzar, Lila; Menas, Ferhat; Müller, Martin Michael

    2015-09-01

    We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically. PMID:26465512

  18. Polar interface phonons in ionic toroidal systems

    NASA Astrophysics Data System (ADS)

    Nguyen, N. D.; Evrard, R.; Stroscio, Michael A.

    2016-09-01

    We use the dielectric continuum model to obtain the polar (Fuchs–Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus.

  19. Continuum damping of ideal toroidal Alfven eigenmodes

    SciTech Connect

    Zhang, X.D.; Zhang, Y.Z.; Mahajan, S.M.

    1993-08-01

    A perturbation theory based on the two dimensional (2D) ballooning transform is systematically developed for ideal toroidal Alfven eigenmodes (TAEs). A formula, similar to the Fermi golden rule for decaying systems in quantum mechanics, is derived for the continuum damping rate of the TAE; the decay (damping) rate is expressed explicitly in terms of the coupling of the TAE to the continuum spectrum. Numerical results are compared with previous calculations. It is found that in some narrow intervals of the parameter m{cflx {epsilon}} the damping rate varies very rapidly. These regions correspond precisely to the root missing intervals of the numerical solution by Rosenbluth et al.

  20. Plasma current resonance in asymmetric toroidal systems

    SciTech Connect

    Hazeltine, R. D.; Catto, Peter J.

    2015-09-15

    The well-known singularity in the magnetic differential equation for plasma current in an asymmetric toroidal confinement system is resolved by including in the pressure tensor corrections stemming from finite Larmor radius. The result provides an estimate of the amplitude of spikes in the parallel current that occur on rational magnetic surfaces. Resolution of the singularity is shown to depend on both the ambipolarity condition—the requirement of zero surface-averaged radial current—and the form of the magnetic differential equation near the rational surface.

  1. Design of toroidal transformers for maximum efficiency

    NASA Technical Reports Server (NTRS)

    Dayton, J. A., Jr.

    1972-01-01

    The design of the most efficient toroidal transformer that can be built given the frequency, volt-ampere rating, magnetic flux density, window fill factor, and materials is described. With the above all held constant and only the dimensions of the magnetic core varied, the most efficient design occurs when the copper losses equal 60 percent of the iron losses. When this criterion is followed, efficiency is only slightly dependent on design frequency and fill factor. The ratios of inside diameter to outside diameter and height to build of the magnetic core that result in transformers of maximum efficiency are computed.

  2. Polar interface phonons in ionic toroidal systems.

    PubMed

    Nguyen, N D; Evrard, R; Stroscio, Michael A

    2016-09-01

    We use the dielectric continuum model to obtain the polar (Fuchs-Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus. PMID:27357246

  3. Proposal to produce large compact toroids

    SciTech Connect

    Phillips, J.A.

    1981-03-01

    Relatively large, hot compact toroids might be produced in the annular space between two concentric one-turn coils. With currents in the two coils flowing in the same direction, the magnetic fields on each side of the plasma are in opposite directions. As the fields are raised, the plasma ring is heated and compressed radially towards the center of the annular space. By the addition of two sets of auxiliary coils, the plasma ring can be ejected out one end of the two-coil system into a long axial magnetic field.

  4. Electromagnetic Torque in Tokamaks with Toroidal Asymmetries

    NASA Astrophysics Data System (ADS)

    Logan, Nikolas Christopher

    Toroidal rotation and rotation shear strongly influences stability and confinement in tokamaks. Breaking of the toroidal symmetry by fields orders of magnitude smaller than the axisymmetric field can, however, produce electromagnetic torques that significantly affect the plasma rotation, stability and confinement. These electromagnetic torques are the study of this thesis. There are two typical types of electromagnetic torques in tokamaks: 1) "resonant torques" for which a plasma current defined by a single toroidal and single poloidal harmonic interact with external currents and 2) "nonresonant torques" for which the global plasma response to nonaxisymmetric fields is phase shifted by kinetic effects that drive the rotation towards a neoclassical offset. This work describes the diagnostics and analysis necessary to evaluate the torque by measuring the rate of momentum transfer per unit area in the vacuum region between the plasma and external currents using localized magnetic sensors to measure the Maxwell stress. These measurements provide model independent quantification of both the resonant and nonresonant electromagnetic torques, enabling direct verification of theoretical models. Measured values of the nonresonant torque are shown to agree well with the perturbed equilibrium nonambipolar transport (PENT) code calculation of torque from cross field transport in nonaxisymmetric equilibria. A combined neoclassical toroidal viscosity (NTV) theory, valid across a wide range of kinetic regimes, is fully implemented for the first time in general aspect ratio and shaped plasmas. The code captures pitch angle resonances, reproducing previously inaccessible collisionality limits in the model. The complete treatment of the model enables benchmarking to the hybrid kinetic MHD stability codes MARS-K and MISK, confirming the energy-torque equivalency principle in perturbed equilibria. Experimental validations of PENT results confirm the torque applied by nonaxisymmetric

  5. Modeling and control of plasma rotation for NSTX using neoclassical toroidal viscosity and neutral beam injection

    NASA Astrophysics Data System (ADS)

    Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; Gates, D. A.; Gerhardt, S. P.; Boyer, M. D.; Andre, R.; Kolemen, E.; Taira, K.

    2016-03-01

    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.

  6. Spontaneous three-dimensional magnetic reconnection in merging toroidal plasma experiment

    SciTech Connect

    Ii, Toru; Ono, Yasushi

    2013-01-15

    We investigated a new phenomenon of three-dimensional (3D) magnetic reconnection in TS-4 torus plasma merging experiments by directly measuring the 3D structures of the current sheet. Removal of all toroidal asymmetry of the device reveals that a strong external drive of reconnection inflow increases the toroidal asymmetry of the current sheet only during the reconnection. This spontaneous 3D deformation of the current sheet increases the reconnection outflow as well as the reconnection electric field, probably because local compression of the current sheet to a thickness less than the ion gyroradius triggers its strong dissipation of the current sheet, responsible for the onset of 3D reconnection. These mechanisms indicate that the 3D reconnection is a newly observed spontaneous process of fast reconnection.

  7. Spontaneous three-dimensional magnetic reconnection in merging toroidal plasma experiment

    NASA Astrophysics Data System (ADS)

    Ii, Toru; Ono, Yasushi

    2013-01-01

    We investigated a new phenomenon of three-dimensional (3D) magnetic reconnection in TS-4 torus plasma merging experiments by directly measuring the 3D structures of the current sheet. Removal of all toroidal asymmetry of the device reveals that a strong external drive of reconnection inflow increases the toroidal asymmetry of the current sheet only during the reconnection. This spontaneous 3D deformation of the current sheet increases the reconnection outflow as well as the reconnection electric field, probably because local compression of the current sheet to a thickness less than the ion gyroradius triggers its strong dissipation of the current sheet, responsible for the onset of 3D reconnection. These mechanisms indicate that the 3D reconnection is a newly observed spontaneous process of fast reconnection.

  8. Highlights from the assembly of the helical field coils for the Advanced Toroidal Facility

    SciTech Connect

    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.

  9. Future Directions for the PEGASUS Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Fonck, R.; Pegasus Team

    1999-11-01

    The PEGASUS Toroidal Experiment is uniquely poised to explore the tokamak/spheromak transition regime in the near future. To this end, a new low-inductance toroidal field coil set will allow transient exploration of the Ip/ITF > 3 regime and associated plasma relaxation phenomena. The addition of a transformer and inline inductor to the ohmic power supply will increase the pulse length to 0.03-0.05 s and will couple 5-10x the present power to the plasma. The High Harmonic Fast Wave (HHFW) antenna is complete and installation is planned for Fall 1999. The power supplies for the HHFW system have been tested up to 0.7 MW into dummy loads with future upgrades to 2 MW. Poloidal current injection via plasma guns is being tested for generating non-inductive target plasmas, thus reducing startup volt second consumption. If successful, a coaxial array of plasma guns will be used to initiate and drive the startup plasma, achieving non-inductive plasma currents 0.1-0.2 MA. Investigation of the viability of Electron Bernstein Wave heating in overdense ST plasmas is also planned, and may lead to an alternative method of non-inductive current ramp and sustainment.

  10. Toroidal Simulations of Sawteeth with Diamagnetic Effects

    NASA Astrophysics Data System (ADS)

    Beidler, Matthew; Cassak, Paul; Jardin, Stephen

    2014-10-01

    The sawtooth crash in tokamaks limits the core temperature, adversely impacts confinement, and seeds disruptions. Adequate knowledge of the physics governing the sawtooth crash and a predictive capability of its ramifications has been elusive, including an understanding of incomplete reconnection, i.e., why sawteeth often cease prematurely before processing all available magnetic flux. There is an indication that diamagnetic suppression could play an important role in this phenomenon. While computational tools to study toroidal plasmas have existed for some time, extended-MHD physics have only recently been integrated. Interestingly, incomplete reconnection has been observed in simulations when diamagnetic effects are present. In the current study, we employ the three-dimensional, extended-MHD code M3D-C1 to study the sawtooth crash in a toroidal geometry. In particular, we describe how magnetic reconnection at the q = 1 rational surface evolves when self-consistently increasing diamagnetic effects are present. We also explore how the termination of reconnection may lead to core-relaxing ideal-MHD instabilities.

  11. Propulsion using the electron spiral toroid

    SciTech Connect

    Seward, Clint

    1998-01-15

    A new propulsion method is proposed which could potentially reduce propellant needed for space travel by three orders of magnitude. It uses the newly patented electron spiral toroid (EST), which stores energy as magnetic field energy. The EST is a hollow toroid of electrons, all spiraling in parallel paths in a thin outer shell. The electrons satisfy the coupling condition, forming an electron matrix. Stability is assured as long as the coupling condition is satisfied. The EST is held in place with a small external electric field; without an external magnetic field. The EST system is contained in a vacuum chamber. The EST can be thought of as an energetic entity, with electrons at 10,000 electron volts. Propulsion would not use combustion, but would heat propellant through elastic collisions with the EST surface and eject them for thrust. Chemical rocket combustion heats propellant to 4000 deg. C; an EST will potentially heat the propellant 29,000 times as much, reducing propellant needs accordingly. The thrust can be turned ON and OFF. The EST can be recharged as needed.

  12. 2-D skin-current toroidal-MHD-equilibrium code

    SciTech Connect

    Feinberg, B.; Niland, R.A.; Coonrod, J.; Levine, M.A.

    1982-09-01

    A two-dimensional, toroidal, ideal MHD skin-current equilibrium computer code is described. The code is suitable for interactive implementation on a minicomptuer. Some examples of the use of the code for design and interpretation of toroidal cusp experiments are presented.

  13. Toroidal rotation induced by asymmetric cyclotron resonance absorption in minority ICRF-heated tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Wang, S.; Zhang, D.

    2016-04-01

    A new mechanism of ion cyclotron range of frequency (ICRF)-induced rotation is proposed to explain the toroidal rotation with minority ICRF heating without net momentum injection. For ICRF waves launched with the symmetric spectrum, a nonlinear toroidal force can be generated through the asymmetric absorption of the toroidal wave momentum, which is due to the finite toroidal rotation of minority ions. This ICRF-induced toroidal force can drive a significant toroidal rotation of bulk ions.

  14. An ACT1 mutation selectively abolishes interleukin-17 responses in humans with chronic mucocutaneous candidiasis.

    PubMed

    Boisson, Bertrand; Wang, Chenhui; Pedergnana, Vincent; Wu, Ling; Cypowyj, Sophie; Rybojad, Michel; Belkadi, Aziz; Picard, Capucine; Abel, Laurent; Fieschi, Claire; Puel, Anne; Li, Xiaoxia; Casanova, Jean-Laurent

    2013-10-17

    Patients with inborn errors of interleukin-17F (IL-17F) or IL-17RA display chronic mucocutaneous candidiasis (CMC). We report a biallelic missense mutation (T536I) in the adaptor molecule ACT1 in two siblings with CMC. The mutation, located in the SEFIR domain, abolished the homotypic interaction of ACT1 with IL-17 receptors, with no effect on homodimerization. The patients' fibroblasts failed to respond to IL-17A and IL-17F, and their T cells to IL-17E. By contrast, healthy individuals homozygous for the common variant D10N, located in the ACT1 tumor necrosis factor receptor-associated factor-interacting domain and previously associated with psoriasis, had impaired, but not abolished, responses to IL-17 cytokines. SEFIR-independent interactions of ACT1 with other proteins, such as CD40, heat shock protein 70 (HSP70) and HSP90, were not affected by the T536I mutation. Overall, human IL-17A and IL-17F depend on ACT1 to mediate protective mucocutaneous immunity. Moreover, other ACT1-dependent IL-17 cytokines seem to be largely redundant in host defense. PMID:24120361

  15. A biallelic ACT1 mutation selectively abolishes interleukin-17 responses in humans with chronic mucocutaneous candidiasis

    PubMed Central

    Boisson, Bertrand; Wang, Chenhui; Pedergnana, Vincent; Wu, Ling; Cypowyj, Sophie; Rybojad, Michel; Belkadi, Aziz; Picard, Capucine; Abel, Laurent; Fieschi, Claire; Puel, Anne; Li, Xiaoxia; Casanova, Jean-Laurent

    2013-01-01

    Patients with inborn errors of IL-17F or IL-17RA display chronic mucocutaneous candidiasis (CMC). We report a biallelic missense mutation (T536I) in the adaptor molecule ACT1 in two siblings with CMC. The mutation, located in the SEFIR domain, abolished the homotypic interaction of ACT1 with IL-17 receptors, with no effect on homodimerization. The patients’ fibroblasts failed to respond to IL-17A and IL-17F, and their T cells to IL-17E. By contrast, healthy individuals homozygous for the common variant D10N, located in the ACT1 TNF receptor-associated factor (TRAF)-interacting domain and previously associated with psoriasis, had impaired, but not abolished, responses to IL-17 cytokines. SEFIR-independent interactions of ACT1 with other proteins, such as CD40, heat shock protein (HSP)70 and HSP90, were not affected by the T536I mutation. Overall, human IL-17A and IL-17F depend on ACT1 to mediate protective mucocutaneous immunity. Moreover, other ACT1-dependent IL-17 cytokines seem to be largely redundant in host defense. PMID:24120361

  16. Silicon-Embedding Approaches to 3-D Toroidal Inductor Fabrication

    SciTech Connect

    Yu, XH; Kim, M; Herrault, F; Ji, CH; Kim, J; Allen, MG

    2013-06-01

    This paper presents complementary-metal-oxide-semiconductor-compatible silicon-embedding techniques for on-chip integration of microelectromechanical-system devices with 3-D complex structures. By taking advantage of the "dead volume" within the bulk of the silicon wafer, functional devices with large profile can be embedded into the substrate without consuming valuable die area on the wafer surface or increasing the packaging complexity. Furthermore, through-wafer interconnects can be implemented to connect the device to the circuitry on the wafer surface. The key challenge of embedding structures within the wafer volume is processing inside deep trenches. To achieve this goal in an area-efficient manner, straight-sidewall trenches are desired, adding additional difficulty to the embedding process. Two approaches to achieve this goal are presented in this paper, i.e., a lithography-based process and a shadow-mask-based process. The lithography-based process utilizes a spray-coating technique and proximity lithography in combination with thick epoxy processing and laminated dry-film lithography. The shadow-mask-based process employs a specially designed 3-D silicon shadow mask to enable simultaneous metal patterning on both the vertical sidewall and the bottom surface of the trench during deposition, eliminating multiple lithography steps and reducing the process time. Both techniques have been demonstrated through the embedding of the topologically complex 3-D toroidal inductors into the silicon substrate for power supply on-chip (PwrSoC) applications. Embedded 3-D inductors that possess 25 turns and a diameter of 6 mm in a silicon trench of 300-mu m depth achieve overall inductances of 45-60 nH, dc resistances of 290-400 m Omega, and quality factors of 16-17.5 at 40-70 MHz.

  17. Segmented saddle-shaped passive stabilization conductors for toroidal plasmas

    DOEpatents

    Leuer, James A.

    1990-05-01

    A large toroidal vacuum chamber for plasma generation and confinement is lined with a toroidal blanket for shielding using modules segmented in the toroidal direction. To provide passive stabilization in the same manner as a conductive vacuum chamber wall, saddle-shaped conductor loops are provided on blanket modules centered on a midplane of the toroidal chamber with horizontal conductive bars above and below the midplane, and vertical conductive legs on opposite sides of each module to provide return current paths between the upper and lower horizontal conductive bars. The close proximity of the vertical legs provided on adjacent modules without making physical contact cancel the electromagnetic field of adjacent vertical legs. The conductive bars spaced equally above and below the midplane simulate toroidal conductive loops or hoops that are continuous, for vertical stabilization of the plasma even though they are actually segmented.

  18. Plasmonic Toroidal Dipolar Response under Radially Polarized Excitation.

    PubMed

    Bao, Yanjun; Zhu, Xing; Fang, Zheyu

    2015-01-01

    Plasmonic toroidal resonance has attracted growing interests because of its low loss electromagnetic properties and potential high sensitive nanophotonic applications. However, the realization in a metamaterial requires three-dimensional complicated structural design so far. In this paper, we design a simple metal-dielectric-metal (MIM) sandwich nanostructure, which exhibits a strong toroidal dipolar resonance under radially polarized excitation. The toroidal dipole moment as the dominant contribution for the scattering is demonstrated by the mirror-image method and further analyzed by Lagrangian hybridization model. The proposed toroidal configuration also shows a highly tolerant for misalignment between the structure center and the incident light focus. Our study proves the way for the toroidal plasmonic application with the cylindrical vector beams. PMID:26114966

  19. Segmented saddle-shaped passive stabilization conductors for toroidal plasmas

    DOEpatents

    Leuer, J.A.

    1990-05-01

    A large toroidal vacuum chamber for plasma generation and confinement is lined with a toroidal blanket for shielding using modules segmented in the toroidal direction. To provide passive stabilization in the same manner as a conductive vacuum chamber wall, saddle-shaped conductor loops are provided on blanket modules centered on a midplane of the toroidal chamber with horizontal conductive bars above and below the midplane, and vertical conductive legs on opposite sides of each module to provide return current paths between the upper and lower horizontal conductive bars. The close proximity of the vertical legs provided on adjacent modules without making physical contact cancel the electromagnetic field of adjacent vertical legs. The conductive bars spaced equally above and below the midplane simulate toroidal conductive loops or hoops that are continuous, for vertical stabilization of the plasma even though they are actually segmented. 5 figs.

  20. Plasmonic Toroidal Dipolar Response under Radially Polarized Excitation

    PubMed Central

    Bao, Yanjun; Zhu, Xing; Fang, Zheyu

    2015-01-01

    Plasmonic toroidal resonance has attracted growing interests because of its low loss electromagnetic properties and potential high sensitive nanophotonic applications. However, the realization in a metamaterial requires three-dimensional complicated structural design so far. In this paper, we design a simple metal-dielectric-metal (MIM) sandwich nanostructure, which exhibits a strong toroidal dipolar resonance under radially polarized excitation. The toroidal dipole moment as the dominant contribution for the scattering is demonstrated by the mirror-image method and further analyzed by Lagrangian hybridization model. The proposed toroidal configuration also shows a highly tolerant for misalignment between the structure center and the incident light focus. Our study proves the way for the toroidal plasmonic application with the cylindrical vector beams. PMID:26114966

  1. Tokamak Fusion Core Experiment: design studies based on superconducting and hybrid toroidal field coils. Design overview

    SciTech Connect

    Flanagan, C.A.

    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.

  2. Perturbing macroscopic magnetohydrodynamic stability for toroidal plasmas

    NASA Astrophysics Data System (ADS)

    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

  3. Epithelial Proliferation on Curved Toroidal Surfaces

    NASA Astrophysics Data System (ADS)

    Chang, Ya-Wen; Cruz, Ricardo; Fragkopoulos, Alexandros; Marquez, Samantha; Garcia, Andres; Fernandez-Nieves, Alberto

    Cellular environment influences a multitude of cellular functions by providing chemical and physical signals that modulate cell behavior, dynamics, development, and eventually survival. In strongly interacting epithelial cells, cells coordinate their behavior to respond to mechanical constraints in 2D. Local differences in tissue tension has also been shown to impact cell reproduction within an epithelial-cell sheet. Much less is known about how cells respond to out-of-plane curvatures. Here, we describe the proliferation of MDCK on toroidal hydrogel substrates, which unlike spheres or planes, have regions of both positive and negative Gaussian curvature. Additionally, the range of curvatures can be controlled by varying the size and aspect ratio of the torus, allowing us to quantify the relation between substrate curvature and cell proliferation.

  4. Progress in toroidal confinement and fusion research

    SciTech Connect

    Furth, H.P.

    1987-10-01

    During the past 30 years, the characteristic T/sub i/n tau/sub E/-value of toroidal-confinement experiments has advanced by more than seven orders of magnitude. Part of this advance has been due to an increase of gross machine parameters. Most of this advance has been due to an increase of gross machine parameters. Most of the advance is associated with improvements in the ''quality of plasma confinement.'' The combined evidence of spherator and tokamak research clarifies the role of magnetic-field geometry in determining confinement and points to the importance of shielding out plasma edge effects. A true physical understanding of anomalous transport remains to be achieved. 39 refs., 11 figs., 1 tab.

  5. Isomorphic routing on a toroidal mesh

    NASA Technical Reports Server (NTRS)

    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.

  6. Nonideal magnetohydrodynamic instabilities and toroidal magnetic confinement

    SciTech Connect

    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.

  7. Toroidal microinstability studies of high temperature tokamaks

    SciTech Connect

    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 /eta//sub i/ /equivalent to/ (dlnT/sub i//dr)/(dlnn/sub i//dr), the characteristic features of the dominant mode are those of the /eta//sub i/-type instability when /eta//sub i/ > /eta//sub ic/ /approximately/1.2 to 1.4 and of the trapped-electron mode when /eta//sub i/ < /eta//sub ic/. 16 refs., 7 figs.

  8. ATF (Advanced Toroidal Facility) data management

    SciTech Connect

    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.

  9. Helicity of a toroidal vortex with swirl

    NASA Astrophysics Data System (ADS)

    Bannikova, E. Yu.; Kontorovich, V. M.; Poslavsky, S. A.

    2016-04-01

    Based on the solutions of the Bragg-Hawthorne equation, we discuss the helicity of a thin toroidal vortex in the presence of swirl, orbital motion along the torus directrix. The relation between the helicity and circulations along the small and large linked circumferences (the torus directrix and generatrix) is shown to depend on the azimuthal velocity distribution in the core of the swirling ring vortex. In the case of nonuniform swirl, this relation differs from the well-known Moffat relation, viz., twice the product of such circulations multiplied by the number of linkages. The results can find applications in investigating the vortices in planetary atmospheres and the motions in the vicinity of active galactic nuclei.

  10. Development of Compact Toroid Injector for C-2 FRCs

    NASA Astrophysics Data System (ADS)

    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.

  11. Model for a transformer-coupled toroidal plasma source

    SciTech Connect

    Rauf, Shahid; Balakrishna, Ajit; Chen Zhigang; Collins, Ken

    2012-01-15

    A two-dimensional fluid plasma model for a transformer-coupled toroidal plasma source is described. Ferrites are used in this device to improve the electromagnetic coupling between the primary coils carrying radio frequency (rf) current and a secondary plasma loop. Appropriate components of the Maxwell equations are solved to determine the electromagnetic fields and electron power deposition in the model. The effect of gas flow on species transport is also considered. The model is applied to 1 Torr Ar/NH{sub 3} plasma in this article. Rf electric field lines form a loop in the vacuum chamber and generate a plasma ring. Due to rapid dissociation of NH{sub 3}, NH{sub x}{sup +} ions are more prevalent near the gas inlet and Ar{sup +} ions are the dominant ions farther downstream. NH{sub 3} and its by-products rapidly dissociate into small fragments as the gas flows through the plasma. With increasing source power, NH{sub 3} dissociates more readily and NH{sub x}{sup +} ions are more tightly confined near the gas inlet. Gas flow rate significantly influences the plasma characteristics. With increasing gas flow rate, NH{sub 3} dissociation occurs farther from the gas inlet in regions with higher electron density. Consequently, more NH{sub 4}{sup +} ions are produced and dissociation by-products have higher concentrations near the outlet.

  12. Spectroscopic Measurements of Non-Hydrogenic Compact Toroids on CTIX

    NASA Astrophysics Data System (ADS)

    Hwang, D. Q.; Buchenauer, D.; Horton, R. D.; Evans, R. W.; Klauser, R.; Whaley, J. A.; Mills, B. E.

    2015-11-01

    The CTIX device is currently being used to investigate the production of compact-toroid plasmas consisting primarily of high-Z ions, using ionization and accretion of high-Z neutrals in the acceleration region. The axial density profile of the high-Z ions will be determined by transverse spectroscopic measurements, which are able to identify particular ion species. Ion velocity can then be deduced from axial time of flight. In addition, high-resolution spectroscopy will be used to directly measure high-Z ion velocity via Doppler shifts. These results are important in determining the degree of slip of high-Z ion velocity relative to CT magnetic field. Scaling of this slippage can be measured as a function of ion species, magnetic field strength, and gas injection location, and compared with a test-particle simulation. The results are relevant to determining the ability of the CT to penetrate a magnetic field, either for the purposes of shock formation study, or for applications to runaway electron suppression in large tokamak experiments. Beneficial effects, in terms of discharge reproducibility and surface durability, for a new tungsten-coated inner electrode will also be presented, along with a design for improved diagnostic access through the outer electrode. This work was supported by USDOE grant # DE-FG02-03ER54732 at UC Davis, and USDOE contract DE-AC04-94AL85000 at Sandia National Laboratories.

  13. Worming Their Way into Shape: Toroidal Formations in Micellar Solutions

    SciTech Connect

    Cardiel Rivera, Joshua J.; Tonggu, Lige; Dohnalkova, Alice; de la Iglesia, Pablo; Pozzo, Danilo C.; Shen, Amy

    2013-11-01

    We report the formation of nanostructured toroidal micellar bundles (nTMB) from a semidilute wormlike micellar solution, evidenced by both cryogenicelectron microscopy and transmission electron microscopy images. Our strategy for creating nTMB involves a two-step protocol consisting of a simple prestraining process followed by flow through a microfluidic device containing an array of microposts, producing strain rates in the wormlike micelles on the order of 105 s^1. In combination with microfluidic confinement, these unusually large strain rates allow for the formation of stable nTMB. Electron microscopy images reveal a variety of nTMB morphologies and provide the size distribution of the nTMB. Small-angle neutron scattering indicates the underlying microstructural transition from wormlike micelles to nTMB. We also show that other flow-induced approaches such as sonication can induce and control the emergence of onion-like and nTMB structures, which may provide a useful tool for nanotemplating.

  14. Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Ida, K.; Kobayashi, T.; Yoshinuma, M.; Suzuki, Y.; Narushima, Y.; Evans, T. E.; Ohdachi, S.; Tsuchiya, H.; Inagaki, S.; Itoh, K.

    2016-09-01

    Bifurcation physics of a magnetic island was investigated using the heat pulse propagation technique produced by the modulation of electron cyclotron heating. There are two types of bifurcation phenomena observed in a large helical device (LHD) and DIII-D. One is a bifurcation of the magnetic topology between nested and stochastic fields. The nested state is characterized by the bi-directional (inward and outward) propagation of the heat pulse with slow propagation speed. The stochastic state is characterized by the fast propagation of the heat pulse with electron temperature flattening. The other bifurcation is between the magnetic island with larger thermal diffusivity and that with smaller thermal diffusivity. The damping of toroidal flow is observed at the O-point of the magnetic island both in helical plasmas and in tokamak plasmas during a mode locking phase with strong flow shears at the boundary of the magnetic island. Associated with the stochastization of the magnetic field, the abrupt damping of toroidal flow is observed in LHD. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. This observation suggests that this flow damping is due to the change in the non-diffusive term of momentum transport.

  15. Mechanical design aspects of the Advanced Toroidal Facility Thomson scattering diagnostic

    SciTech Connect

    Shipley, W.D.; Kindsfather, R.R.; Rasmussen, D.A.

    1987-01-01

    A two-dimensional Thomson scattering system has been designed for the Advanced Toroidal Facility (ATF), a torsatron experiment at the Oak Ridge National Laboratory (ORNL). The system is a modification of the Thomson scattering system used on the Impurity Study Experiment (ISX-B) tokamak. It will provide measurements of electron temperature (T/sub e/) and density (n/sub e/) at 15 points along a vertical chord. With multiple shots, a T/sub e/ and n/sub e/ map of a toroidal cross section of ATF can be obtained. The horizontal Thomson scattering viewing port is offset by 15/sup 0/ toroidally from the ports through which the vertical laser beam passes. The modifications to the ISX-B Thomson scattering system are either changes required to adapt the system to the ATF device geometry or changes that result in improvements to the original system. This paper deals with the mechanical design aspects of the laser light baffle plates that reduce the amount of extraneous light entering the plasma, the upper and lower vacuum extensions that contain the baffles and attach to the ATF vacuum vessel, the entrance window assembly, the laser dump assembly, the viewing window and shutter assembly, and the alignment target mechanism and drive used to determine the ampping of data points in the plasma cross section.

  16. Temperature Effects on the Magnetic Properties of Silicon-Steel Sheets Using Standardized Toroidal Frame

    PubMed Central

    Wu, Cheng-Ju; Lin, Shih-Yu; Chou, Shang-Chin; Tsai, Chia-Yun; Yen, Jia-Yush

    2014-01-01

    This study designed a detachable and standardized toroidal test frame to measure the electromagnetic characteristic of toroidal laminated silicon steel specimens. The purpose of the design was to provide the measurements with standardized and controlled environment. The device also can withstand high temperatures (25–300°C) for short time period to allow high temperature tests. The accompanying driving circuit facilitates testing for high frequency (50–5,000 Hz) and high magnetic flux (0.2–1.8 T) conditions and produces both sinusoidal and nonsinusoidal test waveforms. The thickness of the stacked laminated silicon-steel sheets must be 30~31 mm, with an internal diameter of 72 mm and an outer diameter of 90 mm. With the standardized setup, it is possible to carry out tests for toroidal specimen in high temperature and high flux operation. The test results show that there is a tendency of increased iron loss under high temperature operation. The test results with various driving waveforms also provide references to the required consideration in engineering designs. PMID:25525629

  17. Deformation energy of a toroidal nucleus and plane fragmentation barriers

    NASA Astrophysics Data System (ADS)

    Fauchard, C.; Royer, G.

    1996-02-01

    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.

  18. Kinetic effect of toroidal rotation on the geodesic acoustic mode

    SciTech Connect

    Guo, W. Ye, L.; Zhou, D.; Xiao, X.; Wang, S.

    2015-01-15

    Kinetic effects of the toroidal rotation on the geodesic acoustic mode are theoretically investigated. It is found that when the toroidal rotation increases, the damping rate increases in the weak rotation regime due to the rotation enhancement of wave-particle interaction, and it decreases in the strong rotation regime due to the reduction of the number of resonant particles. Theoretical results are consistent with the behaviors of the geodesic acoustic mode recently observed in DIII-D and ASDEX-Upgrade. The kinetic damping effect of the rotation on the geodesic acoustic mode may shed light on the regulation of turbulence through the controlling the toroidal rotation.

  19. Kinetic energy principle and neoclassical toroidal torque in tokamaks

    SciTech Connect

    Park, Jong-Kyu

    2011-11-15

    It is shown that when tokamaks are perturbed, the kinetic energy principle is closely related to the neoclassical toroidal torque by the action invariance of particles. Especially when tokamaks are perturbed from scalar pressure equilibria, the imaginary part of the potential energy in the kinetic energy principle is equivalent to the toroidal torque by the neoclassical toroidal viscosity. A unified description therefore should be made for both physics. It is also shown in this case that the potential energy operator can be self-adjoint and thus the stability calculation can be simplified by minimizing the potential energy.

  20. Kinetic Energy Principle And Neoclassical Toroidal Torque In Tokamaks

    SciTech Connect

    Jong-Kyu Park

    2011-11-07

    It is shown that when tokamaks are perturbed the kinetic energy principle is closely related to the neoclassical toroidal torque by the action invariance of particles. Especially when tokamaks are perturbed from scalar pressure equilibria, the imaginary part of the potential energy in the kinetic energy principle is equivalent to the toroidal torque by the Neoclassical Toroidal Viscosity (NTV). A unified description therefore should be made for both physics. It is also shown in this case that the potential energy operator can be self-adjoint and thus the stability calculation can be simplified by minimizing the potential energy

  1. Azimuthal Sisyphus effect for atoms in a toroidal all-optical trap

    SciTech Connect

    Lembessis, V. E.; Ellinas, D.; Babiker, M.

    2011-10-15

    It is shown that an optical arrangement in which two identical counterpropagating Laguerre-Gaussian doughnut beams LG(l,0) and LG(-l,0) with orthogonal linear polarizations e {sub x} and e {sub y} can lead to azimuthal polarization gradients and an as yet undiscovered azimuthal Sisyphus effect. It is demonstrated that this effect can be utilized in the creation and control of a persistent current of superfluid atoms circulating in a toroidal trap. Such a physical system has recently been highlighted as the basis for an atomic superconducting quantum interference device (SQUID) and ultimately for the realization of atom circuits.

  2. Gaseous toroid around Saturn. [Saturnian ring system for atomic hydrogen trapping in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    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.

  3. Influence of toroidal rotation on resistive tearing modes in tokamaks

    NASA Astrophysics Data System (ADS)

    Wang, S.; Ma, Z. W.

    2015-12-01

    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 (τR/τV ≫ 1, where τR and τV 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 (τR/τV ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large.

  4. Reversed Field Pinch Dynamics in Toroidal and Cylindrical Geometries

    NASA Astrophysics Data System (ADS)

    Morales, Jorge A.; Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.

    2014-10-01

    The effect of the curvature of the imposed magnetic field on Reversed Field Pinch dynamics is investigated by comparing the flow of a magnetofluid in a torus with aspect ratio 1.83, with the flow in a periodic cylinder. It is found that an axisymmetric toroidal mode is always present in the toroidal, but absent in the cylindrical configuration. In particular, in contrast to the cylinder, the toroidal case presents a double poloidal recirculation cell with a shear localized at the plasma edge. Quasi-single-helicity states are found to be more persistent in toroidal than in periodic cylinder geometry. This work was supported by the contract SiCoMHD (ANR-Blanc 2011-045), computing time was supplied by IDRIS, project 22206.

  5. Influence of toroidal rotation on resistive tearing modes in tokamaks

    SciTech Connect

    Wang, S.; Ma, Z. W.

    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.

  6. High-frequency electric field measurement using a toroidal antenna

    DOEpatents

    Lee, Ki Ha

    2002-01-01

    A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

  7. Visualizing the Formation and Collapse of DNA Toroids

    PubMed Central

    van den Broek, Bram; Noom, Maarten C.; van Mameren, Joost; Battle, Christopher; MacKintosh, Fred C.; Wuite, Gijs J.L.

    2010-01-01

    Abstract In living organisms, DNA is generally confined into very small volumes. In most viruses, positively charged multivalent ions assist the condensation of DNA into tightly packed toroidal structures. Interestingly, such cations can also induce the spontaneous formation of DNA toroids in vitro. To resolve the condensation dynamics and stability of DNA toroids, we use a combination of optical tweezers and fluorescence imaging to visualize in real-time spermine-induced (de)condensation in single DNA molecules. By actively controlling the DNA extension, we are able to follow (de)condensation under tension with high temporal and spatial resolution. We show that both processes occur in a quantized manner, caused by individual DNA loops added onto or removed from a toroidal condensate that is much smaller than previously observed in similar experiments. Finally, we present an analytical model that qualitatively captures the experimentally observed features, including an apparent force plateau. PMID:20441754

  8. Analysis of scrape-off layer in toroidal helical systems

    NASA Astrophysics Data System (ADS)

    Nagasaki, Kazunobu; Itoh, Kimitaka; Itoh, Sanae-I.; Fukuyama, Atsushi

    1990-03-01

    Magnetic field structure of the scrape-off layer region in toroidal helical systems is analyzed by using toroidal harmonic functions. The connection length of the field line to the wall is calculated for various configurations. It is found that L has a logarythmic dependence on the distance from the outermost magnetic surface or from the residual magnetic islands. The effect of the axisymmetric fields on the stress structure is also discussed.

  9. Plasma Behavior in the PEGASUS Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Thorson, T.; Pegasus Team

    1999-11-01

    Initial operations on PEGASUS are focussed on exploring the extremely low aspect ratio regime of operation (A < 1.2) at low toroidal field with ohmic heating. A magnetic null region is achieved for breakdown using the internal poloidal field coils. With a short-pulse ohmic power supply, Ip 0.1 MA has been achieved with A = 1.1 - 1.4 at Bt = 0.07 T. High loop voltage gives a high current ramp, 30-200 MA/sec, and correspondingly highly elongated plasmas (> 3). The plasmas stretch vertically until contact is made with the upper and lower limiters; this is often followed by an influx of impurities and abrupt decrease in the current ramp rate. Strong radial compression results in termination through an n = 0 instability. Low voltage operation with the longer-pulse ohmic power supply should reduce the plasma elongation and control limiter interactions during current channel growth. Completion of the power systems, plus upgrades to the limiters and wall conditioning will allow operation at full pulse length ( ~ 0.05 sec) and plasma current ( ~ 0.3 MA), and thus provide a target plasma for the higher harmonic fast wave heating system.

  10. Turbulent Equipartition Theory of Toroidal Momentum Pinch

    SciTech Connect

    T.S. Hahm, P.H. Diamond, O.D. Gurcan, and G. Rewaldt

    2008-01-31

    The mode-independet part of magnetic curvature driven turbulent convective (TuroCo) pinch of the angular momentum density [Hahm et al., Phys. Plasmas 14,072302 (2007)] which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of "magnetically weighted angular momentum density," nmi U|| R/B2, and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustratd that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms which exist in a simpler geometry.

  11. Toroidal nanotraps for cold polar molecules

    DOE PAGESBeta

    Salhi, Marouane; Passian, Ali; Siopsis, George

    2015-09-14

    Electronic excitations in metallic nanoparticles in the optical regime that have been of great importance in surface-enhanced spectroscopy and emerging applications of molecular plasmonics, due to control and confinement of electromagnetic energy, may also be of potential to control the motion of nanoparticles and molecules. Here, we propose a concept for trapping polarizable particles and molecules using toroidal metallic nanoparticles. Specifically, gold nanorings are investigated for their scattering properties and field distribution to computationally show that the response of these optically resonant particles to incident photons permit the formation of a nanoscale trap when proper aspect ratio, photon wavelength, andmore » polarization are considered. However, interestingly the resonant plasmonic response of the nanoring is shown to be detrimental to the trap formation. The results are in good agreement with analytic calculations in the quasistatic limit within the first-order perturbation of the scalar electric potential. The possibility of extending the single nanoring trapping properties to two-dimensional arrays of nanorings is suggested by obtaining the field distribution of nanoring dimers and trimers.« less

  12. Efficient magnetic fields for supporting toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Landreman, Matt; Boozer, Allen H.

    2016-03-01

    The magnetic field that supports tokamak and stellarator plasmas must be produced by coils well separated from the plasma. However, the larger the separation, the more difficult it is to produce a given magnetic field in the plasma region, so plasma configurations should be chosen that can be supported as efficiently as possible by distant coils. The efficiency of an externally generated magnetic field is a measure of the field's shaping component magnitude at the plasma compared to the magnitude near the coils; the efficiency of a plasma equilibrium can be measured using the efficiency of the required external shaping field. Counterintuitively, plasma shapes with low curvature and spectral width may have low efficiency, whereas plasma shapes with sharp edges may have high efficiency. Two precise measures of magnetic field efficiency, which correctly identify such differences in difficulty, will be examined. These measures, which can be expressed as matrices, relate the externally produced normal magnetic field on the plasma surface to the either the normal field or current on a distant control surface. A singular value decomposition (SVD) of either matrix yields an efficiency ordered basis for the magnetic field distributions. Calculations are carried out for both tokamak and stellarator cases. For axisymmetric surfaces with circular cross-section, the SVD is calculated analytically, and the range of poloidal and toroidal mode numbers that can be controlled to a given desired level is determined. If formulated properly, these efficiency measures are independent of the coordinates used to parameterize the surfaces.

  13. Compact toroid injection into C-2U

    NASA Astrophysics Data System (ADS)

    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.

  14. Toroidal nanotraps for cold polar molecules

    NASA Astrophysics Data System (ADS)

    Salhi, Marouane; Passian, Ali; Siopsis, George

    2015-09-01

    Electronic excitations in metallic nanoparticles in the optical regime that have been of great importance in surface-enhanced spectroscopy and emerging applications of molecular plasmonics, due to control and confinement of electromagnetic energy, may also be of potential to control the motion of nanoparticles and molecules. Here, we propose a concept for trapping polarizable particles and molecules using toroidal metallic nanoparticles. Specifically, gold nanorings are investigated for their scattering properties and field distribution to computationally show that the response of these optically resonant particles to incident photons permit the formation of a nanoscale trap when proper aspect ratio, photon wavelength, and polarization are considered. However, interestingly the resonant plasmonic response of the nanoring is shown to be detrimental to the trap formation. The results are in good agreement with analytic calculations in the quasistatic limit within the first-order perturbation of the scalar electric potential. The possibility of extending the single nanoring trapping properties to two-dimensional arrays of nanorings is suggested by obtaining the field distribution of nanoring dimers and trimers.

  15. Toroidal nanotraps for cold polar molecules

    SciTech Connect

    Salhi, Marouane; Passian, Ali; Siopsis, George

    2015-09-14

    Electronic excitations in metallic nanoparticles in the optical regime that have been of great importance in surface-enhanced spectroscopy and emerging applications of molecular plasmonics, due to control and confinement of electromagnetic energy, may also be of potential to control the motion of nanoparticles and molecules. Here, we propose a concept for trapping polarizable particles and molecules using toroidal metallic nanoparticles. Specifically, gold nanorings are investigated for their scattering properties and field distribution to computationally show that the response of these optically resonant particles to incident photons permit the formation of a nanoscale trap when proper aspect ratio, photon wavelength, and polarization are considered. However, interestingly the resonant plasmonic response of the nanoring is shown to be detrimental to the trap formation. The results are in good agreement with analytic calculations in the quasistatic limit within the first-order perturbation of the scalar electric potential. The possibility of extending the single nanoring trapping properties to two-dimensional arrays of nanorings is suggested by obtaining the field distribution of nanoring dimers and trimers.

  16. Turbulent equipartition theory of toroidal momentum pinch

    SciTech Connect

    Hahm, T. S.; Rewoldt, G.; Diamond, P. H.; Gurcan, O. D.

    2008-05-15

    The mode-independent part of the magnetic curvature driven turbulent convective (TurCo) pinch of the angular momentum density [Hahm et al., Phys. Plasmas 14, 072302 (2007)], which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of 'magnetically weighted angular momentum density', nm{sub i}U{sub parallel}R/B{sup 2}, and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustrated that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms that exist in a simpler geometry.

  17. Toroidal solar collection and energy storage apparatus

    SciTech Connect

    Wasserman, K.J.

    1980-09-23

    Vehicular tires are generally toroidal heat collection elements of a solar heating system. Liquid or gaseous fluid flow is circulated between the tires and a space to be heated for transferring the heat from the tires to the space. The tires are generally vertically stacked within a thermally insulated enclosure which includes a double glazed window located so that solar rays impinge on and heat the tires. Heat storage media such as water, rock or pebble beds, or phase change material in an elongated coiled jacket may be provided within the tires. Downwardly inclined vanes either partially cut from the tire walls or attached to the tires or attached to separators between the tires, provide additional surface area to absorb the solar radiation and to also direct airflow radially inward into the center of the tires. When the vanes are formed by cutting from the tires, they are naturally hinged for elevational angulation and a cable linkage is provided to simultaneously adjust the elevation of the vanes or to close the apertures in the tire walls formed by the cutting out of the vanes. The window is selectively obstructed from light and heat transfer therethrough either by means of a removeable cover or by thermally insulating sliding opaque sheets within the walls of the enclosure which are selectively positionable between the double glazing.

  18. Tearing Mode Stability of Evolving Toroidal Equilibria

    NASA Astrophysics Data System (ADS)

    Pletzer, A.; McCune, D.; Manickam, J.; Jardin, S. C.

    2000-10-01

    There are a number of toroidal equilibrium (such as JSOLVER, ESC, EFIT, and VMEC) and transport codes (such as TRANSP, BALDUR, and TSC) in our community that utilize differing equilibrium representations. There are also many heating and current drive (LSC and TORRAY), and stability (PEST1-3, GATO, NOVA, MARS, DCON, M3D) codes that require this equilibrium information. In an effort to provide seamless compatibility between the codes that produce and need these equilibria, we have developed two Fortran 90 modules, MEQ and XPLASMA, that serve as common interfaces between these two classes of codes. XPLASMA provides a common equilibrium representation for the heating and current drive applications while MEQ provides common equilibrium and associated metric information needed by MHD stability codes. We illustrate the utility of this approach by presenting results of PEST-3 tearing stability calculations of an NSTX discharge performed on profiles provided by the TRANSP code. Using the MEQ module, the TRANSP equilibrium data are stored in a Fortran 90 derived type and passed to PEST3 as a subroutine argument. All calculations are performed on the fly, as the profiles evolve.

  19. Axisymmetric toroidal modes of general relativistic magnetized neutron star models

    SciTech Connect

    Asai, Hidetaka; Lee, Umin E-mail: lee@astr.tohoku.ac.jp

    2014-07-20

    We calculate axisymmetric toroidal modes of magnetized neutron stars with a solid crust in the general relativistic Cowling approximation. We assume that the interior of the star is threaded by a poloidal magnetic field, which is continuous at the surface with an outside dipole field. We examine the cases of the field strength B{sub S} ∼ 10{sup 16} G at the surface. Since separation of variables is not possible for the oscillations of magnetized stars, we employ finite series expansions for the perturbations using spherical harmonic functions. We find discrete normal toroidal modes of odd parity, but no toroidal modes of even parity are found. The frequencies of the toroidal modes form distinct mode sequences and the frequency in a given mode sequence gradually decreases as the number of radial nodes of the eigenfunction increases. From the frequency spectra computed for neutron stars of different masses, we find that the frequency is almost exactly proportional to B{sub S} and is well represented by a linear function of R/M for a given B{sub S}, where M and R are the mass and radius of the star. The toroidal mode frequencies for B{sub S} ∼ 10{sup 15} G are in the frequency range of the quasi-periodic oscillations (QPOs) detected in the soft-gamma-ray repeaters, but we find that the toroidal normal modes cannot explain all the detected QPO frequencies.

  20. Spontaneous toroidal flow generation due to negative effective momentum diffusivity

    SciTech Connect

    McMillan, Ben F.

    2015-02-15

    Spontaneous structure formation, and in particular, zonal flows, is observed in a broad range of natural and engineered systems, often arising dynamically as the saturated state of a linear instability. Flows in tokamaks are known to self-organise on small scales, but large scale toroidal flows also arise even when externally applied torques are zero. This has previously been interpreted as the result of small externally imposed breaking of a symmetry. However, we show that for large enough field line pitch, a robust spontaneous symmetry breaking occurs, leading to the generation of strong toroidal flow structures; parameters are typical of Spherical Tokamak discharges with reversed shear profiles. The short wavelength dynamics are qualitatively similar to the growth of poloidal flow structures, and toroidal flow gradients nonlinearly saturate at levels where the shearing rate is comparable to linear growth rate. On long wavelengths, we measure Prandtl numbers of around zero for these systems, in conjunction with the formation of structured toroidal flows, and we show that this is consistent with a model of momentum transport where fluxes act to reinforce small flow gradients: the effective momentum diffusivity is negative. Toroidal flow structures are largely unaffected by collisional damping, so this may allow toroidal bulk flows of order the ion thermal velocity to be maintained with zero momentum input. This phenomenon also provides a mechanism for the generation of localised meso-scale structures like transport barriers.

  1. Transport and dynamics in toroidal fusion systems. Report of second year progress, 1993--1994

    SciTech Connect

    Schnack, D.D.

    1994-05-09

    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.

  2. Toroidal Momentum Pinch Velocity due to the Coriolis Drift Effect on Small Scale Instabilities in a Toroidal Plasma

    SciTech Connect

    Peeters, A. G.; Angioni, C.; Strintzi, D.

    2007-06-29

    In this Letter, the influence of the ''Coriolis drift'' on small scale instabilities in toroidal plasmas is shown to generate a toroidal momentum pinch velocity. Such a pinch results because the Coriolis drift generates a coupling between the density and temperature perturbations on the one hand and the perturbed parallel flow velocity on the other. A simple fluid model is used to highlight the physics mechanism and gyro-kinetic calculations are performed to accurately assess the magnitude of the pinch. The derived pinch velocity leads to a radial gradient of the toroidal velocity profile even in the absence of a torque on the plasma and is predicted to generate a peaking of the toroidal velocity profile similar to the peaking of the density profile. Finally, the pinch also affects the interpretation of current experiment000.

  3. Drift mode calculations for the Large Helical Device

    SciTech Connect

    G. Rewoldt; L.-P. Ku; W.M. Tang; H. Sugama; N. Nakajima; K.Y. Watanabe; S. Murakami; H. Yamada; W.A. Cooper

    2000-06-08

    A fully kinetic assessment of the stability properties of toroidal drift modes has been obtained for a case for the Large Helical Device (LHD) [A.Iiyoshi, et al., Plasma Physics and Controlled Nuclear Fusion Research, 1998, Nucl.Fusion 39, 1245 (1999)]. This calculation retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. Results for toroidal drift waves destabilized by trapped particle dynamics and ion temperature gradients are presented, using three-dimensional magnetohydrodynamics equilibria reconstructed from experimental measurements. The effects of helically-trapped particles and helical curvature are investigated.

  4. Modeling and control of plasma rotation and βn for NSTX-U using Neoclassical Toroidal Viscosity and Neutral Beam Injection

    NASA Astrophysics Data System (ADS)

    Goumiri, Imene; Rowley, Clarence; Sabbagh, Steven; Gates, David; Gerhardt, Stefan; Boyer, Mark

    2015-11-01

    A model-based system is presented allowing control of the plasma rotation profile in a magnetically confined toroidal fusion device to maintain plasma stability for long pulse operation. The analysis, using NSTX data and NSTX-U TRANSP simulations, is aimed at controlling plasma rotation using momentum from six injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields as actuators. Based on the momentum diffusion and torque balance model obtained, a feedback controller is designed and predictive simulations using TRANSP will be presented. Robustness of the model and the rotation controller will be discussed.

  5. Role of geometry in optothermal response of toroidal ultra-high-Q cavities

    NASA Astrophysics Data System (ADS)

    Soltani, Soheil; Armani, Andrea M.

    2015-03-01

    Ultra-high quality factor (UHQ) resonant cavities are able to store light for long periods of time, resulting in high circulating intensities. As a result, numerous nonlinear optical phenomena appear, such as radiation pressure oscillations and lasing. However, deleterious behaviors also occur, such as optothermal broadening of the resonant linewidth. The degree of distortion is directly related to the circulating power in the cavity, the material absorption, and the thermo-optic coefficient of the cavity material. Specifically, a portion of the circulating power is absorbed by the material and converted to heat. This thermal energy is able to induce a refractive index change in the cavity which is experimentally observed as a resonant wavelength change. This behavior has been observed in numerous cavities, but one interesting case is the toroidal cavity, as it has a particularly complex geometry providing multiple thermal transport pathways. To accurately capture this complex behavior, we have developed a COMSOL Multiphysics model which combines the thermal and optical components. The model uses the non-uniform optical mode profile as the heat source. As such, changes in device geometry and wavelength are inherently captured. To verify the modeling, we characterize the optothermal threshold for a series of toroidal cavities across a range of wavelengths and device geometries. Additionally, the thermal time constant of the structure is explored. Of note, the membrane thickness is shown to play a critical role in the optothermal behaviors.

  6. Control of toroidal-like asymmetries in a heliac

    NASA Astrophysics Data System (ADS)

    Spanjers, G. G.; Nelson, B. A.; Ribe, F. L.; Jarboe, T. R.; Barnes, D. C.

    1993-05-01

    A simple modification to the heliac coil configuration [A. H. Boozer et al., Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1966), Vol. 1, p. 103] is described that reduces the toroidal perturbation to the magnetic field structure and significantly restores the helical symmetry. This is accomplished by shifting the internal current-carrying conductor (hardcore) of the heliac radially inward from its normal position at the geometric center of the external l=1 coils. It is shown by computations that a large-aspect-ratio toroidal heliac is similar to a helically symmetric linear heliac in which the hardcore has been shifted. This similarity is seen in the analytic form of the magnetic potential, the flux surface shape, and in the harmonic spectra of the field lines. It is then shown that the toroidicity perturbations can be reduced in a toroidal heliac by combining these effects—using a radially inward hardcore shift in the toroidal configuration. In the experiments reported here the toroidal-like effects are created in the linear High Beta Q Machine (HBQM) heliac [C. M. Greenfield et al., Phys. Fluids B 2, 133 (1990)] by shifting the hardcore off the geometric center of the l=1 coils. The induced toroidal-like effects are seen from an asymmetry in the axial excluded flux; however, no decrease in global beta is seen as compared to the unshifted symmetric case (G. G. Spanjers, Ph.D. dissertation, University of Washington, 1992) indicating the absence of large-scale magnetohydrodynamic instabilities at high beta.

  7. Basic physics of Alfven instabilities driven by energetic particles in toroidally confined plasmas

    SciTech Connect

    Heidbrink, W. W.

    2008-05-15

    Superthermal energetic particles (EP) often drive shear Alfven waves unstable in magnetically confined plasmas. These instabilities constitute a fascinating nonlinear system where fluid and kinetic nonlinearities can appear on an equal footing. In addition to basic science, Alfven instabilities are of practical importance, as the expulsion of energetic particles can damage the walls of a confinement device. Because of rapid dispersion, shear Alfven waves that are part of the continuous spectrum are rarely destabilized. However, because the index of refraction is periodic in toroidally confined plasmas, gaps appear in the continuous spectrum. At spatial locations where the radial group velocity vanishes, weakly damped discrete modes appear in these gaps. These eigenmodes are of two types. One type is associated with frequency crossings of counterpropagating waves; the toroidal Alfven eigenmode is a prominent example. The second type is associated with an extremum of the continuous spectrum; the reversed shear Alfven eigenmode is an example of this type. In addition to these normal modes of the background plasma, when the energetic particle pressure is very large, energetic particle modes that adopt the frequency of the energetic particle population occur. Alfven instabilities of all three types occur in every toroidal magnetic confinement device with an intense energetic particle population. The energetic particles are most conveniently described by their constants of motion. Resonances occur between the orbital frequencies of the energetic particles and the wave phase velocity. If the wave resonance with the energetic particle population occurs where the gradient with respect to a constant of motion is inverted, the particles transfer energy to the wave, promoting instability. In a tokamak, the spatial gradient drive associated with inversion of the toroidal canonical angular momentum P{sub {zeta}} is most important. Once a mode is driven unstable, a wide variety

  8. Summary of US-Japan Exchange 2004 New Directions and Physics for Compact Toroids

    SciTech Connect

    Intrator, T; Nagata, M; Hoffman, A; Guo, H; Steinhauer, L; Ryutov, D; Miller, R; Okada, S

    2005-08-15

    This exchange workshop was an open meeting coordinated by the P-24 Plasma Physics Group at Los Alamos National Laboratory. We brought together scientists from institutions in the US and Japan who are researching the various and complementary types of Compact Toroids (CT). Many concepts, including both experimental and theoretical investigations, are represented. The range spans Field Reversed Configuration (FRC), spheromak, Reversed Field Pinch (RFP), spherical tokamaks, linear devices dedicated to fundamental physics studies, and hybrid transitions that bridge multiple configurations. The participants represent facilities on which significant experiments are now underway: FRC Injection experiment (FIX), Translation Confinement experiment (TCS), Nihon-University Compact Torus Experiment (NUCTE), HITSI (Helicity Injection experiment, Steady Inductive Helicity Injection (HIT-SIHI)), Field Reversed Configuration experiment-Liner (FRX-L), TS-3/4, Sustained Spheromak Experiment (SSPX), Relaxation Scaling Experiment (RSX), HIST, Caltech Spheromak, or in the design process such as MRX-FRC (PPPL), Pulsed High Density experiment (PHD at UW). Several new directions and results in compact toroid (CT) research have recently emerged, including neutral-beam injection, rotating magnetic fields, flux build up from Ohmic boost coils, electrostatic helicity injection techniques, CT injection into other large devices, and high density configurations for applications to magnetized target fusion and translational compression of CT's. CT experimental programs in both the US and Japan have also shown substantial progress in the control and sustainment of CT's. Both in theory and experiment, there is increased emphasis on 3D dynamics, which is also related to astrophysical and space physics issues. 3D data visualization is now frequently used for experimental data display. There was much discussion of the effects of weak toroidal fields in FRC's and possible implications for transport and

  9. IL-17-induced Act1-mediated signaling is critical for cuprizone-induced demyelination

    PubMed Central

    Kang, Zizhen; Liu, Liping; Spangler, Roo; Spear, Charles; Wang, Chenhui; Gulen, Muhammet Fatih; Veenstra, Mike; Ouyang, Wenjun; Ransohoff, Richard M.; Li, Xiaoxia

    2012-01-01

    Cuprizone inhibits mitochondrial function and induces demyelination in the corpus callosum which resembles pattern III lesions in multiple sclerosis (MS) patients. However, the molecular and cellular mechanism by which cuprizone induces demyelination remains unclear. Interleukin-17 (IL-17) secreted by T helper 17 (Th17) cells and γδT cells are essential in the development of experimental autoimmune encephalomyelitis (EAE). In this study, we examined the importance of IL-17 signaling in cuprizone-induced demyelination. We found that mice deficient in IL-17A, IL-17RC and adaptor protein Act1 (of IL-17R) all had reduced demyelination accompanied by lessened microglial and polydendrocyte cellular reactivity compared to that in wild-type mice in response to cuprizone feeding, demonstrating the essential role of IL-17-induced Act1-mediated signaling in cuprizone-induced demyelination. Importantly, specific deletion of Act1 in astrocytes reduced the severity of tissue injury in this model, indicating the critical role of CNS resident cells in the pathogenesis of cuprizone-induced demyelination. In cuprizone-fed mice IL-17 was produced by CNS CD3+ T cells suggesting a source of IL-17 in CNS upon cuprizone treatment. PMID:22699909

  10. IL-17-induced Act1-mediated signaling is critical for cuprizone-induced demyelination.

    PubMed

    Kang, Zizhen; Liu, Liping; Spangler, Roo; Spear, Charles; Wang, Chenhui; Gulen, Muhammet Fatih; Veenstra, Mike; Ouyang, Wenjun; Ransohoff, Richard M; Li, Xiaoxia

    2012-06-13

    Cuprizone inhibits mitochondrial function and induces demyelination in the corpus callosum, which resembles pattern III lesions in multiple sclerosis patients. However, the molecular and cellular mechanism by which cuprizone induces demyelination remains unclear. Interleukin-17 (IL-17) secreted by T helper 17 cells and γδT cells are essential in the development of experimental autoimmune encephalomyelitis. In this study, we examined the importance of IL-17 signaling in cuprizone-induced demyelination. We found that mice deficient in IL-17A, IL-17 receptor C (IL-17RC), and adaptor protein Act1 (of IL-17R) all had reduced demyelination accompanied by lessened microglial and polydendrocyte cellular reactivity compared with that in wild-type mice in response to cuprizone feeding, demonstrating the essential role of IL-17-induced Act1-mediated signaling in cuprizone-induced demyelination. Importantly, specific deletion of Act1 in astrocytes reduced the severity of tissue injury in this model, indicating the critical role of CNS resident cells in the pathogenesis of cuprizone-induced demyelination. In cuprizone-fed mice, IL-17 was produced by CNS CD3(+) T cells, suggesting a source of IL-17 in CNS upon cuprizone treatment. PMID:22699909

  11. Physics models in the toroidal transport code PROCTR

    SciTech Connect

    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.

  12. Theory for neoclassical toroidal plasma viscosity in tokamaks

    NASA Astrophysics Data System (ADS)

    Shaing, K. C.; Chu, M. S.; Hsu, C. T.; Sabbagh, S. A.; Seol, Jae Chun; Sun, Y.

    2012-12-01

    Error fields and magnetohydrodynamic modes break toroidal symmetry in tokamaks. The broken symmetry enhances the toroidal plasma viscosity, which results in a steady-state toroidal plasma flow. A theory for neoclassical toroidal plasma viscosity in the low-collisionality regimes is developed. It extends stellarator transport theory to include multiple modes and to allow for |m - nq| ˜ 1. Here, m is the poloidal mode number, n is the toroidal mode number and q is the safety factor. The bounce averaged drift kinetic equation is solved in several asymptotic limits to obtain transport fluxes. These fluxes depend non-linearly on the radial electric field except for those in the 1/ν regime. Here, ν is the collision frequency. The theory is refined to include the effects of the superbanana plateau resonance at the phase space boundary and the finite ∇B drift on the collisional boundary layer fluxes. Analytical expressions that connect all asymptotic limits are constructed and are in good agreement with the numerical results. The flux-force relations that relate transport fluxes to forces are used to illustrate the roles of transport fluxes in the momentum equation. It is shown that the ambipolar state is reached when the momentum equation is relaxed. It is also shown that the origin of the momentum for plasma flow generated without momentum sources is the local unbalance of particles' momenta and is diamagnetic in nature regardless of the details of the theory.

  13. Toroidal Plasma Thruster for Interplanetary and Interstellar Space Flights

    SciTech Connect

    N.N. Gorelenkov; L.E. Zakharov; and M.V. Gorelenkova

    2001-07-11

    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.

  14. Toroidal linear force-free magnetic fields with axial symmetry

    NASA Astrophysics Data System (ADS)

    Vandas, M.; Romashets, E.

    2016-01-01

    Aims: Interplanetary magnetic flux ropes are often described as linear force-free fields. To account for their curvature, toroidal configurations must be used. The aim is to find an analytic description of a linear force-free magnetic field of the toroidal geometry in which the cross section of flux ropes can be controlled. Methods: The solution is found as a superposition of fields given by linear force-free cylinders tangential to a generating toroid. The cylindrical field is expressed in a series of terms that are not all cylindrically symmetric. Results: We found the general form of a toroidal linear force-free magnetic field. The field is azimuthally symmetric with respect to the torus axis. It depends on a set of coefficients that enables controlling the flux rope shape (cross section) to some extent. By varying the coefficients, flux ropes with circular and elliptic cross sections were constructed. Numerical comparison suggests that the simple analytic formula for calculating the helicity in toroidal flux ropes of the circular cross section can be used for flux ropes with elliptic cross sections if the minor radius in the formula is set to the geometric mean of the semi-axes of the elliptic cross section.

  15. Busbar for the low aspect ratio device

    SciTech Connect

    Bromberg, L.; Sidorov, M.

    1996-12-31

    The high current required to drive the toroidal field coil of Low Aspect Ratio reactor-size devices (due to the single turn design) results in difficult choices for the electrical bus. In this paper, the implications of both superconducting and resistive busbar are investigated. Special attention is given to the possibility of using a high-Tc busbar. 14 refs., 5 figs.

  16. Experimental Investigation of Rotational, Pumping, Magnetic Pumping and Toroidal Asymmetry Modes in a Toroidal Electron Plasma

    NASA Astrophysics Data System (ADS)

    Doares, A. R.; Wang, K.; Patterson, A. S.; Stoneking, M. R.

    2014-10-01

    Electron plasma is confined with a purely toroidal magnetic field in the Lawrence Non-Neutral Torus II (R0 = 18 cm, a ~ 2 cm), for times (~1 s) that are much longer than any of the dynamical timescales of the system. The experiment can be operated as a variable-length partial torus or a full torus trap. The damping rate for the m = 1 diocotron mode in a partial torus trap is found to depend on the equilibrium position (major radius) and on magnetic field (150 G--550 G). We report on efforts to explain these results in terms of rotational and magnetic pumping effects using 3D (Poisson-Boltzmann) equilibria calculations. Novel full torus asymmetry modes are examined with multiple separatrices and a new charge tomography is developed to infer charge density from image charge measurements on the conducting boundary. This work is supported by National Science Foundation Award No. 1202540.

  17. Modeling and control of plasma rotation for NSTX using Neoclassical Toroidal Viscosity (NTV) and Neutral Beam Injection (NBI)

    NASA Astrophysics Data System (ADS)

    Goumiri, Imene; Rowley, Clarence; Sabbagh, Steven; Gates, David; Gerhardt, Stefan

    2014-10-01

    A model-based system to control plasma rotation in a magnetically confined toroidal fusion device is developed to maintain plasma stability for long pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed to control plasma rotation by using momentum from injected neutral beams and viscosity generated by three-dimensional applied magnetic fields as actuators. Based on the data driven model obtained, a feedback controller is designed to theoretically sustain the toroidal momentum of the plasma in a stable fashion and to achieve desired plasma rotation profiles. On going work includes extending this method to NSTX Upgrade which has more complete radial coverage of the neutral beams momentum sources which enable simultaneous control of plasma stored energy (Beta control).

  18. Monte Carlo simulation of initial breakdown phase for magnetised toroidal ICRF discharges

    SciTech Connect

    Tripský, M.; Van Oost, G.; Collaboration: ASDEX Upgrade Team; TEXTOR Team

    2014-02-12

    The radio-frequency (RF) plasma production technique in the ion cyclotron range of frequency (ICRF) attracts growing attention among fusion experts because of its high potential for solving several basic problems of reactor-oriented superconducting fusion machines, such as ICRF wall conditioning in tokamaks and stellarators (T{sub e} = 3−5eV, n{sub e}<10{sup 12}cm{sup −3}), ICRF-assisted tokamak start-up and target plasma production (n{sub e} = 10{sup 13}cm{sup −3}) in stellarators. Plasma initiation by ICRF has been studied intensively using single particle descriptions and basic analytic models. To further improve the present understanding on plasma production employing the vacuum RF field of ICRF antennas in toroidal devices in presence of the toroidal magnetic field, and its parametric dependencies a Monte Carlo code has been developed. The 1D code RFdinity1D describes the motion of electrons, accelerated by the RF field in front of the ICRF antenna, along one toroidal magnetic field line. Dependent on their individual energies and the related electron collision cross sections (ionisation, excitation and dissociation) weighted by a Monte Carlo procedure, an electron avalanche may occur. Breakdown conditions are discussed as function of RF discharge parameters (i) RF vacuum electric field strength, (ii) RF frequency and (iii) neutral pressure (H2). The slope of the exponential density increase, taken as measure for the breakdown speed, shows qualitative agreement to experimental breakdown times as found in literature and experimental data of the ASDEX upgrade and TEXTOR tokamak, and is interpreted by studying the characteristic electron velocity distribution functions.

  19. Toroidal Variable-Line-Space Gratings: The Good, the Bad and The Ugly

    NASA Technical Reports Server (NTRS)

    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.

  20. Vlasov tokamak equilibria with shearad toroidal flow and anisotropic pressure

    NASA Astrophysics Data System (ADS)

    Throumoulopoulos, George; Kuiroukidis, Apostolos; Tasso, Henri

    2015-11-01

    By choosing appropriate deformed Maxwellian ion and electron distribution functions depending on the two particle constants of motion, i.e. the energy and toroidal angular momentum, we reduce the Vlasov axisymmetric equilibrium problem for quasineutral plasmas to a transcendental Grad-Shafranov-like equation. This equation is then solved numerically under the Dirichlet boundary condition for an analytically prescribed boundary possessing a lower X-point to construct tokamak equilibria with toroidal sheared ion flow and anisotropic pressure. Depending on the deformation of the distribution functions these steady states can have toroidal current densities either peaked on the magnetic axis or hollow. These two kinds of equilibria may be regarded as a bifurcation in connection with symmetry properties of the distribution functions on the magnetic axis. This work has received funding from (a) the National Programme for the Controlled Thermonuclear Fusion, Hellenic Republic, (b) Euratom research and training programme 2014-2018 under grant agreement No 633053.

  1. Toroidal Superheavy Nuclei in Skyrme-Hartree-Fock Approach

    SciTech Connect

    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.

  2. Topology of tokamak plasma equilibria with toroidal current reversal

    SciTech Connect

    Rodrigues, Paulo; Bizarro, Joao P. S.

    2012-01-15

    Some general principles about scalar functions with critical points are used to rigorously ascertain that magnetic equilibria with both toroidal current reversal and nested magnetic surfaces are atypical solutions and highly unstable to arbitrary perturbations of boundary conditions and other parameters. The cause for such is shown to lie in the condition of nested magnetic surfaces and not in the possibility of current reversal and consequent vanishing of the poloidal field inside the plasma. Rather than supporting the claim that instability against experimentally driven perturbations forbids configurations with toroidal current reversal, it is argued that these can be attained if an axisymmetric island system is allowed for in order to break the condition of nested magnetic surfaces. A number of results previously reported in the literature are discussed and reinterpreted under the proposed framework, providing some physical insight on the nature of equilibria with toroidal current reversal.

  3. Method to integrate full particle orbit in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Wei, X. S.; Xiao, Y.; Kuley, A.; Lin, Z.

    2015-09-01

    It is important to integrate full particle orbit accurately when studying charged particle dynamics in electromagnetic waves with frequency higher than cyclotron frequency. We have derived a form of the Boris scheme using magnetic coordinates, which can be used effectively to integrate the cyclotron orbit in toroidal geometry over a long period of time. The new method has been verified by a full particle orbit simulation in toroidal geometry without high frequency waves. The full particle orbit calculation recovers guiding center banana orbit. This method has better numeric properties than the conventional Runge-Kutta method for conserving particle energy and magnetic moment. The toroidal precession frequency is found to match that from guiding center simulation. Many other important phenomena in the presence of an electric field, such as E × B drift, Ware pinch effect and neoclassical polarization drift are also verified by the full orbit simulation.

  4. Vlasov tokamak equilibria with sheared toroidal flow and anisotropic pressure

    SciTech Connect

    Kuiroukidis, Ap; Throumoulopoulos, G. N.; Tasso, H.

    2015-08-15

    By choosing appropriate deformed Maxwellian ion and electron distribution functions depending on the two particle constants of motion, i.e., the energy and toroidal angular momentum, we reduce the Vlasov axisymmetric equilibrium problem for quasineutral plasmas to a transcendental Grad-Shafranov-like equation. This equation is then solved numerically under the Dirichlet boundary condition for an analytically prescribed boundary possessing a lower X-point to construct tokamak equilibria with toroidal sheared ion flow and anisotropic pressure. Depending on the deformation of the distribution functions, these steady states can have toroidal current densities either peaked on the magnetic axis or hollow. These two kinds of equilibria may be regarded as a bifurcation in connection with symmetry properties of the distribution functions on the magnetic axis.

  5. Novel Design for Centrifugal Countercurrent Chromatography: I. Zigzag Toroidal Column.

    PubMed

    Yang, Yi; Aisa, Haji Akber; Ito, Yoichiro

    2009-01-01

    The toroidal coil using an equilateral triangular core has improved both retention of the stationary phase and peak resolution of the conventional toroidal coil in centrifugal countercurrent chromatography. To further improve the retention of stationary phase and peak resolution, a novel zigzag toroidal coil was designed and the performance of the system was evaluated at various flow rates. The results indicated that both retention of stationary phase and peak resolution were improved as the flow rate was decreased. Modification of the tubing by pressing at given intervals with a pair of pliers improved the peak resolution without increasing the column pressure. All these separations were performed under low column pressure indicating the separation can be further improved by increasing the column length and/or revolution speed without damaging the separation column. PMID:20046954

  6. Profiling compact toroid plasma density on CTIX with laser deflection

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel Joseph Erwin

    A laser deflectometer measures line-integrated plasma density gradient using laser diodes and amplified point detectors. A laser passing through an optically thin plasma is refracted by an amount proportional to the line-integrated electron density gradient. I have designed, installed, and operated a deflection diagnostic for the Compact Toroid Injection Experiment (CTIX), a plasma rail gun which can create compact toroid (CT) plasmas of controllable density and velocity. The diagnostic design and motivation are discussed, as well as three experiments performed with deflectometry. Thus, my thesis consists of the design of the deflectometer diagnostic, a comparison of its accuracy to interferometer density measurements, and finally a survey of compact toroid density profiles in two dimensions conducted with an array of detectors.

  7. Dynamics of the Disruption Halo Current Toroidal Asymmetry in NSTX

    SciTech Connect

    S.P. Gerhardt

    2012-09-27

    This paper describes the dynamics of disruption halo current non-axisymmetries in the lower divertor of the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)]. While. The halo currents typically have a strongly asymmetric structure where they enter the divertor floor, and this asymmetry has been observed to complete up to 7 toroidal revolutions over the duration of the halo current pulse. However, the rotation speed and toroidal extend of the asymmetry can vary significantly during the pulse. The rotation speed, halo current pulse duration, and total number of revolutions tend to be smaller in cases with large halo currents. The halo current pattern is observed to become toroidally symmetric at the end of the halo current pulse. It is proposed that this symmeterization is due to the loss of most or all of the closed field line geometry in the final phase of the vertical displacement event.

  8. Bi-2223 HTS winding in toroidal configuration for SMES coil

    NASA Astrophysics Data System (ADS)

    Kondratowicz-Kucewicz, B.; Janowski, T.; Kozak, S.; Kozak, J.; Wojtasiewicz, G.; Majka, M.

    2010-06-01

    Energy can be stored in the magnetic field of a coil. Superconducting Magnetic Energy Storage (SMES) is very promising as a power storage system for load levelling or power stabilizer. However, the strong electromagnetic force caused by high magnetic field and large coil current is a problem in SMES systems. A toroidal configuration would have a much less extensive external magnetic field and electromagnetic forces in winding. The paper describes the design of HTS winding for SMES coil in modular toroid configuration consist of seven Bi-2223 double-pancakes as well as numerical analysis of SMES magnet model using FLUX 3D package. As the results of analysis the paper presents the optimal coil configuration and the parameters such as radius of toroidal magnet, energy stored in magnet and magnetic field distribution.

  9. Propagations of drift waves in toroidal plasma systems

    SciTech Connect

    Yoshikawa, S.; Cheng, C.Z.

    1990-05-01

    Drift wave patterns in toroidal plasmas are studied. The dispersion relation was simplified to retain both the shear and the toroidal coupling effects. Since the dispersion relation does not depend on the toroidal angle, {phi}, the dispersion is solved in the two- dimensional space made up with minor radius and poloidal angle. The dispersion relation can be reduced into second-order, partial differential equations of a hyperbolic type. The one-dimensional convective mode analysis, which was originated in the 1960's, was extended into the two-dimensional analysis. Depending on the strength of the magnetic shear, one can obtain either the convective or the localized solutions. The results show that the plasma is expected to be unstable for large azimuthal mode number and that the plasma instability tends to be more stabilized for large mass ions. 8 refs., 3 figs., 1 tab.

  10. Polymer- and salt-induced toroids of hexagonal DNA.

    PubMed Central

    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 the concentrations of inert polymer and added salt. The stability of the torus is analyzed in terms of its surface tension and a bulk melting criterion. The theory should be applicable to psi-toroids that are not too thick. PMID:7711268

  11. High-Q toroidal cavities for high frequency klystrons.

    NASA Technical Reports Server (NTRS)

    Branch, G. M.

    1972-01-01

    A toroidal cavity developed for a 4-KW 12 GHz satellite-borne television transmitter klystron is described. The cavity has an internal Q 40% higher than that of a conventional cylindrical doubly reentrant cavity, thus yielding higher circuit efficiency and conserving energy which cannot be recovered in multistage depressed potential beam collectors. As a result of optimization studies with a digital computer program for obtaining cavity field distributions by a relaxation method and for computing the intrinsic cavity parameters, a particular cavity configuration with conical reentrant tunnel tips and toroidal walls is shown to provide good thermal characteristics and mechanical rigidity as well as low internal losses.

  12. Dynamically controlled toroidal and ring-shaped magnetic traps

    SciTech Connect

    Fernholz, T.; Gerritsma, R.; Spreeuw, R. J. C.; Krueger, P.

    2007-06-15

    We present traps with toroidal (T{sup 2}) and ring-shaped topologies based on adiabatic potentials for radio-frequency-dressed Zeeman states in a ring-shaped magnetic quadrupole field. Simple adjustment of the radio-frequency fields provides versatile possibilities for dynamical parameter tuning, topology change, and controlled potential perturbation. We show how to induce toroidal and poloidal rotations, and demonstrate the feasibility of preparing degenerate quantum gases with reduced dimensionality and periodic boundary conditions. The great level of dynamical and even state-dependent control is useful for atom interferometry.

  13. On the longitudinal coupling impedance of a toroidal beam tube

    SciTech Connect

    Hahn, H.; Tepikian, S.

    1990-01-01

    In this paper, the longitudinal coupling impedance of a smooth toroidal beam tube is derived. By treating the torus as a slow-wave structure, the well-known method of describing the impedance in terms of cavity resonances can be used. A simple analytical expression for the coupling impedance of a toroidal beam tube with square cross section valid in the low-frequency limit is obtained. The results from the present study are compared with previously published solutions and qualitative differences are pointed out. 16 refs., 3 figs., 1 tab.

  14. On the vector Helmholtz equation in toroidal waveguides

    SciTech Connect

    Biro, Thomas

    2005-02-15

    A wave splitting method is proposed to solve the problem of propagation of microwaves in a circular waveguide bend of circular cross section. The splitting method, applied to the vector Helmholtz equation, gives a stable solution in terms of waves propagating to the right and to the left in the bend. The formulation is particularly transparent for analyzing the scattering properties of toroidal bends. The basis for the transparency of the method is that the wave splitting is formally exact as the exponential of the square root of a differential operator. The modal functions of the straight cylindrical waveguide are chosen as basis functions in the transverse quasi-toroidal variables.

  15. Experimental characterization of drift-interchange instabilities in a simple toroidal plasma

    SciTech Connect

    Poli, F. M.; Brunner, S.; Diallo, A.; Fasoli, A.; Furno, I.; Labit, B.; Mueller, S. H.; Plyushchev, G.; Podesta, M.

    2006-10-15

    Low frequency electrostatic instabilities are investigated on TORPEX [Fasoli, Labit, McGrath, Mueller, Podesta, and Poli, Bull. Am. Phys. Soc. 48, 119 (2003)], a toroidal device for basic plasma physics experiments with a toroidal magnetic field 100 mT and a small vertical magnetic field ({<=}4 mT). A two-dimensional (2D) profile of the frequency and amplitude of density and potential fluctuations is reconstructed using electrostatic probes with high space and time resolution. The measured phase velocity, corrected for the Doppler shift induced by the ExB drift, is consistent with the electron diamagnetic drift velocity. The local dispersion relation, measured along and across the magnetic field, is in agreement with the predictions of a linear kinetic slab model for drift waves. Unstable modes are generated in regions of unfavorable curvature, where the pressure gradient is colinear with the magnetic field gradient. It is demonstrated that the curvature of the magnetic field lines is essential for driving the observed instabilities, which are therefore identified as drift-interchange modes.

  16. Resonant Transparency and Non-Trivial Non-Radiating Excitations in Toroidal Metamaterials

    PubMed Central

    Fedotov, V. A.; Rogacheva, A. V.; Savinov, V.; Tsai, D. P.; Zheludev, N. I.

    2013-01-01

    Engaging strongly resonant interactions allows dramatic enhancement of functionalities of many electromagnetic devices. However, resonances can be dampened by Joule and radiation losses. While in many cases Joule losses may be minimized by the choice of constituting materials, controlling radiation losses is often a bigger problem. Recent solutions include the use of coupled radiant and sub-radiant modes yielding narrow asymmetric Fano resonances in a wide range of systems, from defect states in photonic crystals and optical waveguides with mesoscopic ring resonators to nanoscale plasmonic and metamaterial systems exhibiting interference effects akin to electromagnetically-induced transparency. Here we demonstrate theoretically and confirm experimentally a new mechanism of resonant electromagnetic transparency, which yields very narrow isolated symmetric Lorentzian transmission lines in toroidal metamaterials. It exploits the long sought non-trivial non-radiating charge-current excitation based on interfering electric and toroidal dipoles that was first proposed by Afanasiev and Stepanovsky in [J. Phys. A Math. Gen. 28, 4565 (1995)]. PMID:24132231

  17. Resonant transparency and non-trivial non-radiating excitations in toroidal metamaterials.

    PubMed

    Fedotov, V A; Rogacheva, A V; Savinov, V; Tsai, D P; Zheludev, N I

    2013-01-01

    Engaging strongly resonant interactions allows dramatic enhancement of functionalities of many electromagnetic devices. However, resonances can be dampened by Joule and radiation losses. While in many cases Joule losses may be minimized by the choice of constituting materials, controlling radiation losses is often a bigger problem. Recent solutions include the use of coupled radiant and sub-radiant modes yielding narrow asymmetric Fano resonances in a wide range of systems, from defect states in photonic crystals and optical waveguides with mesoscopic ring resonators to nanoscale plasmonic and metamaterial systems exhibiting interference effects akin to electromagnetically-induced transparency. Here we demonstrate theoretically and confirm experimentally a new mechanism of resonant electromagnetic transparency, which yields very narrow isolated symmetric Lorentzian transmission lines in toroidal metamaterials. It exploits the long sought non-trivial non-radiating charge-current excitation based on interfering electric and toroidal dipoles that was first proposed by Afanasiev and Stepanovsky in [J. Phys. A Math. Gen. 28, 4565 (1995)]. PMID:24132231

  18. Toroidal transducer with two large focal zones for increasing the coagulated volume

    NASA Astrophysics Data System (ADS)

    Vincenot, J.; Melodelima, D.; Kocot, A.; Chavrier, F.; Chapelon, J. Y.

    2012-11-01

    Toroidal HIFU transducers have been shown to generate large conical ablations (7 cm3 in 40 seconds). The focal zone is composed of a first ring-shaped focal zone and an overlap of ultrasound beams behind this first focus. A HIFU device has been developed on this principle to treat liver metastases during an open procedure. Although these large lesions contribute to reduce treatment time, it is still needed to juxtapose 4 to 9 single HIFU lesions to treat liver metastasis (2 cm in diameter) with safety margins. In this work, a different toroidal geometry was used. With this transducer, the overlap area is located between the probe and the focal ring. The objective was to use this transducer with electronic focusing in order to create a spherical shape lesion with sufficient volume for the destruction of a metastasis of 2 cm in diameter without any mechanical displacement. The operating frequency of the toroidal transducer was 2.5 MHz. The radius of curvature was 70 mm with a diameter of 67 mm. The focal ring had a radius of 15 mm. The overlap zone extent between 35 to 55 mm from the emitting surface. An ultrasound-imaging probe (working at 7.5 MHz) was placed in a central circular opening of 26 mm in the HIFU transducer and was aligned with the focal plane. The transducer was divided into 32 rings of 78 mm2. Using a 32 channels amplifier with a phase resolution of 1.4 degrees, it was possible to change the diameter (0 to 15 mm) and depth (45 to 85 mm) of the focus circle to maximize dimensions of the lesion. Tests were conducted in vitro, in bovine liver samples. This toroidal geometry and the use of electronic beam steering allow the creation of roughly spherical lesions (diameter of 47 mm, depth of 35 mm). This treatment was obtained in 6 minutes and 10 seconds without any mechanical displacement of the transducer. The lesions obtained were homogeneous and no untreated area was observed. In conclusion, these results indicate that the treatment of a liver

  19. Non-solenoidal Plasma Startup in the Pegasus Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Sontag, Aaron

    2008-11-01

    Non-solenoidal (NS) startup will simplify the design of future tokamaks by eliminating need for a central solenoid and is required for an ST based CTF. In Pegasus, washer-stack current sources (plasma guns) are used to initiate NS discharges via point-source DC helicity injection. Current injected parallel to the helical vacuum field can relax into a tokamak-like configuration with toroidally-averaged closed flux and tokamak-like confinement. This requires no modification of the vacuum vessel and is scalable to fusion grade systems with proper geometry. Guns in the divertor region create discharges with Ip up to 50 kA, 3 times the vacuum windup. Nonlinear 3D simulation with NIMROD shows excitation of a line-tied kink, producing poloidal flux amplification. Evidence of flux amplification includes: reversal of edge poloidal magnetic flux; Ip increase over vacuum geometric windup; plasma position subject to radial force balance; and persistence of Ip after gun shut-off. Equilibria show high edge current (li = 0.2) and elevated q (qmin> 6), allowing access to high IN (IN> 12). Guns at the outboard midplane produce Ip up to 7 times the vacuum windup with large n=1 activity when edge q passes through rational surfaces. Line averaged density up to 2x10^19 m-3 after relaxation shows an increase in particle confinement over non-relaxed cases. Maximum Ip is determined by helicity and radial force balance, tokamak stability, and Taylor relaxation. Coupling midplane gun discharges to other CD is straightforward due to Ip decay times >3 ms. Poloidal field induction has been used to create NS discharges up to 80 kA and gun plasmas with Ip of 60 kA have been ramped to over 100 kA by including OH drive. Present research is aimed at understanding the physics of this technique in order to form NS targets in excess of 200 kA and design NS startup systems for larger devices.

  20. Microinstability Studies for the Large Helical Device

    SciTech Connect

    G. Rewoldt; L.-P. Ku; W.M. Tang; H. Sugama; N. Nakajima; K.Y. Watanabe; S. Murakami; H. Yamada; W.A. Cooper

    2002-01-28

    Fully kinetic assessments of the stability properties of toroidal drift modes have been obtained for cases for the Large Helical Device (LHD). This calculation employs the comprehensive linear microinstability code FULL, as recently extended for nonaxisymmetric systems. The code retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. These effects include trapped particles, FLR, transit and bounce and magnetic drift frequency resonances, etc., for any number of plasma species. Results for toroidal drift waves destabilized by trapped electrons and ion temperature gradients are presented, using numerically-calculated three-dimensional MHD equilibria. These are reconstructed from experimental measurements. Quasilinear fluxes of particles and energy for each species are also calculated. Pairs of LHD discharges with different magnetic axis positions and with and without pellet injection are compared.

  1. Computational Knowledge for Toroidal Confinement Physics: Part I

    SciTech Connect

    Chang, C. S.

    2009-02-19

    Basic high level computational knowledge for studying the toroidal confinement physics is discussed. Topics include the primacy hierarchy of simulation quantities in statistical plasma physics, importance of the nonlinear-multiscale self-organization phenomena in a computational study, different types of codes for different applications, and different types of computer architectures for different types of codes.

  2. Development of a high capacity toroidal Ni/Cd cell

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Foos, J. S.; Avery, J. W.; Feiman, V.

    1981-01-01

    A nickel cadmium battery design which can offer better thermal management, higher energy density and much lower cost than the state-of-the-art is emphasized. A toroidal Ni/Cd cell concept is described. It was critically reviewed and used to develop two cell designs for practical implementation. One is a double swaged and the other a swaged welded configuration.

  3. Flat-band assembly for toroidal transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.

    1973-01-01

    Toroidal transformer cores are often banded together by means of strap. Spot welds secure strap. Proper tension is obtained by use of special fixture in conjunction with winding of wire which is placed temporarily on core; winding is excited by dc current to hold core halves together magnetically during alignment.

  4. Kinetic studies of microinstabilities in toroidal plasmas: Simulation and theory

    SciTech Connect

    Lee, W.W.; Haham, T.S.; Parker, S.E.; Perkins, F.W.; Rath, S.; Rewoldt, G.; Reynders, J.V.W.; Santoro, R.A.; Tang, W.M.

    1992-12-01

    A comprehensive program for the development and use of particle simulation techniques for solving the gyrokinetic Vlasov-Maxwell equations on massively parallel computers has been carried out at Princeton Plasma Physics Laboratory. This is a key element of our ongoing theoretical efforts to systematically investigate physics issues vital to understanding tokamak plasmas. In this paper, our focus is on spatial-gradient-driven microinstabilities. Their importance is supported by the recent progress in achieving a physics-based understanding of anomalous transport in toroidal systems which has been based on the proposition that these drift-type electrostatic modes dependent on ion temperature gradient (ITG) and trapped particle effects are dominant in the bulk ( confinement'') region. Although their presence is consistent with a number of significant confinement trends, results from high temperature tokamaks such as TFTR have highlighted the need for better insight into the nonlinear properties of such instabilities in long-mean-free-path plasmas. In addressing this general issue, we report important new results including (i) the first fully toroidal 3D gyrokinetic simulation of ITG modes and (ii) realistic toroidal eigenmode calculations demonstrating the unique capability to deal with large scale kinetic behavior extending over many rational surfaces. The effects of ITG modes (iii) on the inward pinch of impurities in 3D slab geometry and (iv) on the existence of microtearing modes in 2D slab are also discussed. Finally, (v) sheared toroidal flow effects on trapped-particle modes are presented.

  5. Kinetic studies of microinstabilities in toroidal plasmas: Simulation and theory

    SciTech Connect

    Lee, W.W.; Haham, T.S.; Parker, S.E.; Perkins, F.W.; Rath, S.; Rewoldt, G.; Reynders, J.V.W.; Santoro, R.A.; Tang, W.M.

    1992-12-01

    A comprehensive program for the development and use of particle simulation techniques for solving the gyrokinetic Vlasov-Maxwell equations on massively parallel computers has been carried out at Princeton Plasma Physics Laboratory. This is a key element of our ongoing theoretical efforts to systematically investigate physics issues vital to understanding tokamak plasmas. In this paper, our focus is on spatial-gradient-driven microinstabilities. Their importance is supported by the recent progress in achieving a physics-based understanding of anomalous transport in toroidal systems which has been based on the proposition that these drift-type electrostatic modes dependent on ion temperature gradient (ITG) and trapped particle effects are dominant in the bulk (``confinement``) region. Although their presence is consistent with a number of significant confinement trends, results from high temperature tokamaks such as TFTR have highlighted the need for better insight into the nonlinear properties of such instabilities in long-mean-free-path plasmas. In addressing this general issue, we report important new results including (i) the first fully toroidal 3D gyrokinetic simulation of ITG modes and (ii) realistic toroidal eigenmode calculations demonstrating the unique capability to deal with large scale kinetic behavior extending over many rational surfaces. The effects of ITG modes (iii) on the inward pinch of impurities in 3D slab geometry and (iv) on the existence of microtearing modes in 2D slab are also discussed. Finally, (v) sheared toroidal flow effects on trapped-particle modes are presented.

  6. Simulated Textures of Toroidal Nematic Liquid Crystal Droplets

    NASA Astrophysics Data System (ADS)

    Ellis, Perry; Fernandez-Nieves, Alberto

    2014-03-01

    Nematic liquid crystals under confinement by curved surfaces can produce complex hierarchical structures whose design principles and properties have yet to be unraveled. Here we focus on toroidal geometries and perform computer simulations of the nematic textures seen between crossed-polarizers. We find agreement with experiments using director fields that exhibit pronounced twist deformations with contributions from bend and splay.

  7. Toroidal midplane neutral beam armor and plasma limiter

    DOEpatents

    Kugel, H.W.; Hand, S.W. Jr.; Ksayian, H.

    1985-05-31

    This invention contemplates an armor shield/plasma limiter positioned upon the inner wall of a toroidal vacuum chamber within which is magnetically confined an energetic plasma in a tokamak nuclear fusion reactor. The armor shield/plasma limiter is thus of a general semi-toroidal shape and is comprised of a plurality of adjacent graphite plates positioned immediately adjacent to each other so as to form a continuous ring upon and around the toroidal chamber's inner wall and the reactor's midplane coil. Each plate has a generally semi-circular outer circumference and a recessed inner portion and is comprised of upper and lower half sections positioned immediately adjacent to one another along the midplane of the plate. With the upper and lower half sections thus joined, a channel or duct is provided within the midplane of the plate in which a magnetic flux loop is positioned. The magnetic flux loop is thus positioned immediately adjacent to the fusing toroidal plasma and serves as a diagnostic sensor with the armor shield/plasma limiter minimizing the amount of power from the energetic plasma as well as from the neutral particle beams heating the plasma incident upon the flux loop.

  8. The ATF (Advanced Toroidal Facility) Status and Control System

    SciTech Connect

    Baylor, L.R.; Devan, W.R.; Sumner, J.N.; Alban, A.M.

    1987-01-01

    The Advanced Toroidal Facility (ATF) Status and Control System (SCS) is a programmable controller-based state monitoring and supervisory control system. This paper describes the SCS implementation and its use of a host computer to run a commercially available software package that provides color graphic interactive displays, alarm logging, and archiving of state data.

  9. Collisional damping of the geodesic acoustic mode with toroidal rotation. I. Viscous damping

    NASA Astrophysics Data System (ADS)

    Gong, Xueyu; Xie, Baoyi; Guo, Wenfeng; Chen, You; Yu, Jiangmei; Yu, Jun

    2016-03-01

    With the dispersion relation derived for the geodesic acoustic mode in toroidally rotating tokamak plasmas using the fluid model, the effect of the toroidal rotation on the collisional viscous damping of the geodesic acoustic mode is investigated. It is found that the collisional viscous damping of the geodesic acoustic mode has weak increase with respect to the toroidal Mach number.

  10. Development and testing of the ACT-1 experimental facility for hypersonic combustion research

    NASA Astrophysics Data System (ADS)

    Baccarella, D.; Liu, Q.; Passaro, A.; Lee, T.; Do, H.

    2016-04-01

    A new pulsed-arc-heated hypersonic wind tunnel facility, designated as ACT-1 (Arc-heated Combustion Test-rig 1), has been developed and built at the University of Notre Dame in collaboration with the University of Illinois at Urbana-Champaign and Alta S.p.A. The aim of the design is to provide a suitable test platform for experimental studies on supersonic and hypersonic turbulent combustion phenomena. ACT-1 is composed of a high temperature gas-generator system and a model scramjet combustor that is installed in an open-type vacuum test section of the wind tunnel facility. The gas-generator is designed to produce high-enthalpy (stagnation temperature  =  2000 K-3500 K) hypersonic flows for a run time up to 1 s. The supersonic combustor section is composed of a compression ramp (scramjet inlet), an internal flow channel of constant cross-section, a fuel jet nozzle, and a flame holder (wall cavity). The facility allows three-way optical accesses (top and sides) into the supersonic combustor to enable various advanced optical and laser diagnostics. In particular, planar laser Rayleigh scattering (PLRS), high-speed schlieren imaging and OH-planar laser induced fluorescence (OH-PLIF) have successfully been implemented to visualize the turbulent flows and flame structures at high speed flight conditions.

  11. Driving toroidally asymmetric current through the tokamak scrape-off layer, Part I: Potential for ELM suppression

    SciTech Connect

    Joseph, I; Cohen, R H; Ryutov, D D

    2009-03-31

    A potential technique for suppressing edge localized magnetohydrodynamic instabilities (ELMs) is theoretically analyzed. Recent experiments have shown that externally generated resonant magnetic perturbations (RMPs) can stabilize ELMs by modifying the density profile [T. E. Evans, et al., Nature Phys. 2, 419 (2006); Y. Liang, et al., Phys. Rev. Lett. 98, 265004 (2007)]. Driving toroidally asymmetric current internally, through the scrape-off layer (SOL) plasma itself, can also generate RMPs that are close to the required threshold for ELM control. The limiting ion saturation current densities can be achieved by producing potential differences on the order of the electron temperature. Although the threshold is uncertain in future devices, if driven coherently though the SOL, the upper limit for the resulting field would exceed the present experimental threshold. This analysis provides the tools required for estimating the magnitude of the coherent SOL current and RMP generated via toroidally asymmetric biasing of the target. Flux expansion increases the RMP near the X-point, while phase interference due to the shearing of field lines near the X-point reduces the amplitude of the effective SOL perturbation and makes the result sensitive to both toroidal mode number n and the radial coherence width of the biasing region. If the limiting current density decays rapidly enough radially, both the width and the amplitude of the current density drawn from the target will be reduced. The RMP can still exceed the present threshold at low n if the radial location and width of the biasing region are optimally chosen.

  12. Density Limits in Toroidal Magnetic Confinement Experiments

    NASA Astrophysics Data System (ADS)

    Greenwald, Martin

    2001-10-01

    The density limit represents one of the fundamental operating boundaries for magnetic confinement devices - one with practical importance to the goal of fusion power. With fusion reactivity maximized at a plasma temperature on the order of 10 keV and a reaction rate scaling as n^2, an optimum density can be calculated which is not guaranteed to be achievable in any given device. Unlike operational limits for plasma current or pressure, the density limit cannot be explained by magneto-hydrodynamics alone. There is general agreement that the proximate cause for the disruptive limit in the tokamak is cooling of the plasma edge and subsequent current profile shrinkage. The edge cooling may be dominated by atomic physics processes or as suggested in recent experiments, by anomalous transport. A similar picture is emerging for the reversed field pinch (RFP), while the limit in stellarators is apparently due to loss of thermal equilibrium from radiation. Empirical scaling laws in which the maximum plasma density is proportional to the average current density have been fairly successful in predicting the limit for subsequent experiments. Surprisingly, the density limits found in tokamaks and RFPs are virtually identical. Currentless stellarators reach similar density limits, though the expression needs to be recast in terms of the rotational transform. While scaling laws have done a reasonable job in describing data from many recent experiments, they can only give hints at the underlying physics. Understanding the mechanism for the density limit is crucial for extrapolating machine performance into untested regimes and so far, a completely satisfactory theory has not emerged. It seems likely that robust, reliable predictions will only come from the development of a first-principles theory backed up by detailed experimental observations. The extensive work already accomplished and reviewed here should provide a solid basis for such development.

  13. Toroidal mode number estimation of the edge-localized modes using the KSTAR 3-D electron cyclotron emission imaging system

    SciTech Connect

    Lee, J.; Yun, G. S. Lee, J. E.; Kim, M.; Choi, M. J.; Lee, W.; Park, H. K.; Domier, C. W.; Luhmann, N. C.; Sabbagh, S. A.; Park, Y. S.; Lee, S. G.; Bak, J. G.

    2014-06-15

    A new and more accurate technique is presented for determining the toroidal mode number n of edge-localized modes (ELMs) using two independent electron cyclotron emission imaging (ECEI) systems in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The technique involves the measurement of the poloidal spacing between adjacent ELM filaments, and of the pitch angle α{sub *} of filaments at the plasma outboard midplane. Equilibrium reconstruction verifies that α{sub *} is nearly constant and thus well-defined at the midplane edge. Estimates of n obtained using two ECEI systems agree well with n measured by the conventional technique employing an array of Mirnov coils.

  14. Toroidal mode number estimation of the edge-localized modes using the KSTAR 3-D electron cyclotron emission imaging system.

    PubMed

    Lee, J; Yun, G S; Lee, J E; Kim, M; Choi, M J; Lee, W; Park, H K; Domier, C W; Luhmann, N C; Sabbagh, S A; Park, Y S; Lee, S G; Bak, J G

    2014-06-01

    A new and more accurate technique is presented for determining the toroidal mode number n of edge-localized modes (ELMs) using two independent electron cyclotron emission imaging (ECEI) systems in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The technique involves the measurement of the poloidal spacing between adjacent ELM filaments, and of the pitch angle α* of filaments at the plasma outboard midplane. Equilibrium reconstruction verifies that α* is nearly constant and thus well-defined at the midplane edge. Estimates of n obtained using two ECEI systems agree well with n measured by the conventional technique employing an array of Mirnov coils. PMID:24985817

  15. Finding Regions of Interest on Toroidal Meshes

    SciTech Connect

    Wu, Kesheng; Sinha, Rishi R; Jones, Chad; Ethier, Stephane; Klasky, Scott; Ma, Kwan-Liu; Shoshani, Arie; Winslett, Marianne

    2011-02-09

    Fusion promises to provide clean and safe energy, and a considerable amount of research effort is underway to turn this aspiration intoreality. This work focuses on a building block for analyzing data produced from the simulation of microturbulence in magnetic confinementfusion devices: the task of efficiently extracting regions of interest. Like many other simulations where a large amount of data are produced,the careful study of ``interesting'' parts of the data is critical to gain understanding. In this paper, we present an efficient approach forfinding these regions of interest. Our approach takes full advantage of the underlying mesh structure in magnetic coordinates to produce acompact representation of the mesh points inside the regions and an efficient connected component labeling algorithm for constructingregions from points. This approach scales linearly with the surface area of the regions of interest instead of the volume as shown with bothcomputational complexity analysis and experimental measurements. Furthermore, this new approach is 100s of times faster than a recentlypublished method based on Cartesian coordinates.

  16. The Implementation of Magnetic Islands in Gyrokinetic Toroidal Code

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Lin, Zhihong; Ihor, Holod; Xiao, Chijie

    2016-02-01

    The implementation of magnetic islands in gyrokinetic simulation has been verified in the gyrokinetic toroidal code (GTC). The ion and electron density profiles become partially flattened inside the islands. The density profile at the low field side is less flattened than that at the high field side due to toroidally trapped particles in the low field side, which do not move along the perturbed magnetic field lines. When the fraction of trapped particles decreases, the density profile at the low field becomes more flattened. supported by National Special Research Program of China for ITER (Nos. 2013GB111000 and 2014GB107004), China Scholarship Council (No. 2011601098), U.S. DOE Grants DE-SC0010416 and DE-FG02-07ER54916

  17. Neoclassical electron and ion transport in toroidally rotating plasmas

    SciTech Connect

    Sugama, H.; Horton, W.

    1997-06-01

    Neoclassical transport processes of electrons and ions are investigated in detail for toroidally rotating axisymmetric plasmas with large flow velocities on the order of the ion thermal speed. The Onsager relations for the flow-dependent neoclassical transport coefficients are derived from the symmetry properties of the drift kinetic equation with the self-adjoint collision operator. The complete neoclassical transport matrix with the Onsager symmetry is obtained for the rotating plasma consisting of electrons and single-species ions in the Pfirsch{endash}Schl{umlt u}ter and banana regimes. It is found that the inward banana fluxes of particles and toroidal momentum are driven by the parallel electric field, which are phenomena coupled through the Onsager symmetric off-diagonal coefficients to the parallel currents caused by the radial thermodynamic forces conjugate to the inward fluxes, respectively. {copyright} {ital 1997 American Institute of Physics.}

  18. Nonlinear particle simulation of ion cyclotron waves in toroidal geometry

    SciTech Connect

    Kuley, A. Lin, Z.; Bao, J.; Wei, X. S.; Xiao, Y.

    2015-12-10

    Global particle simulation model has been developed in this work to provide a first-principles tool for studying the nonlinear interactions of radio frequency (RF) waves with plasmas in tokamak. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation with realistic electron-to-ion mass ratio. Boris push scheme for the ion motion has been developed in the toroidal geometry using magnetic coordinates and successfully verified for the ion cyclotron and ion Bernstein waves in global gyrokinetic toroidal code (GTC). The nonlinear simulation capability is applied to study the parametric decay instability of a pump wave into an ion Bernstein wave side band and a low frequency ion cyclotron quasi mode.

  19. The toroidal field coil design for ARIES-ST

    SciTech Connect

    Reiersen, W.; Dahlgren, F.; Fan, H.M.; Neumeyer, C.; Zatz, I.

    2000-01-21

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

  20. Nuclear magnetic resonance tomography with a toroid cavity detector

    SciTech Connect

    Woelk, K.; Rathke, J.W.; Klingler, R.J.

    1995-02-01

    A new type of nuclear magnetic resonance (NMR) tomography has been developed at Argonne National Laboratory. The method uses the strong radio frequency field gradient within a cylindrical toroid cavity to provide high-resolution NMR spectral information while simultaneously resolving distances on the micron scale. The toroid cavity imaging technique differs from conventional magnetic resonance imaging (MRI) in that NMR structural information is not lost during signal processing. The new technique could find a wide range of applications in the characterization of surface layers and in the production of advanced materials. Potential areas of application include in situ monitoring of growth sites during ceramic formation processes, analysis of the oxygen annealing step for wires coated with high-temperature superconducting films, and investigation of the reaction chemistry as a function of distance within the diffusion layer for electrochemical processes.

  1. Stabilization of ballooning modes with sheared toroidal rotation

    SciTech Connect

    Miller, R.L.; Waelbroeck, F.W.; Lao, L.L.; Taylor, T.S.

    1994-11-01

    A new code demonstrates the stabilization of MHD ballooning modes by sheared toroidal rotation. A shifted-circle model is used to elucidate the physics and numerically reconstructed equilibria are used to analyze DIII-D discharges. In the ballooning representation, the modes shift periodically along the field line to the next point of unfavorable curvature. The shift frequency (d{Omega}/dq where {Omega} 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, in the shifted circle model, direct stable access to the second stability regime occurs when this frequency is a fraction of the Alfven frequency {omega}{sub A} = V{sub A}/qR. Shear stabilization is also demonstrated for an equilibrium reconstruction of a DIII-D VH-mode.

  2. Toroidal momentum transport in a tokamak due to profile shearing

    SciTech Connect

    Buchholz, R.; Grosshauser, S. R.; Hornsby, W. A.; Migliano, P.; Peeters, A. G.; Camenen, Y.; Casson, F. J.

    2014-06-15

    The effect of profile shearing on toroidal momentum transport is studied in linear and non-linear gyro-kinetic simulations. Retaining the radial dependence of both plasma and geometry parameters leads to a momentum flux that has contributions both linear in the logarithmic gradients of density and temperature, as well as contributions linear in the derivatives of the logarithmic gradients. The effect of the turbulence intensity gradient on momentum transport is found to be small for the studied parameters. Linear simulations at fixed normalized toroidal wave number predict a weak dependence of the momentum flux on the normalized Larmor radius ρ{sub *}=ρ/R. Non-linear simulations, however, at sufficiently small ρ{sub *} show a linear scaling of the momentum flux with ρ{sub *}. The obtained stationary rotation gradients are in the range of, although perhaps smaller than, current experiments. For a reactor plasma, however, a rather small rotation gradient should result from profile shearing.

  3. Closed expressions for the magnetic field of toroidal multipole configurations

    SciTech Connect

    Sheffield, G.V.

    1983-04-01

    Closed analytic expressions for the vector potential and the magnetic field for the lower order toroidal multipoles are presented. These expressions can be applied in the study of tokamak plasma cross section shaping. An example of such an application is included. These expressions also allow the vacuum fields required for plasma equilibrium to be specified in a general form independent of a particular coil configuration.

  4. Antenna excitation of drift wave in a toroidal plasma

    SciTech Connect

    Diallo, A.; Ricci, P.; Fasoli, A.; Furno, I.; Labit, B.; Mueller, S. H.; Podesta, M.; Poli, F. M.; Skiff, F.

    2007-10-15

    In a magnetized toroidal plasma, an antenna tunable in vertical wave number is used to excite density perturbations. Coherent detection is performed by means of Langmuir probes to directly determine both the wave vector and the plasma response induced by the antenna. Comparison between the theoretical density response predicted by the generalized Hasegawa-Wakatani model, and the experimentally determined density response enables us the identification of one peak of the plasma response as a drift wave.

  5. Evolution of the alpha particle driven toroidicity induced Alfven mode

    SciTech Connect

    Wu, Y.; White, R.B.; Cheng, C.Z.

    1994-04-01

    The interaction of alpha particles with a toroidicity induced Alfven eigenmode is investigated self-consistently by using a kinetic dispersion relation. All important poloidal harmonics and their radial mode profiles are included. A Hamiltonian guiding center code is used to simulate the alpha particle motion. The simulations include particle orbit width, nonlinear particle dynamics and the effects of the modes on the particles. Modification of the particle distribution leading to mode saturation is observed. There is no significant alpha particle loss.

  6. Dual Telecentric Lens System For Projection Onto Tilted Toroidal Screen

    NASA Technical Reports Server (NTRS)

    Gold, Ronald S.; Hudyma, Russell M.

    1995-01-01

    System of two optical assemblies for projecting image onto tilted toroidal screen. One projection lens optimized for red and green spectral region; other for blue. Dual-channel approach offers several advantages which include: simplified color filtering, simplified chromatic aberration corrections, less complex polarizing prism arrangement, and increased throughput of blue light energy. Used in conjunction with any source of imagery, designed especially to project images formed by reflection of light from liquid-crystal light valve (LCLV).

  7. Toroidal qubits: naturally-decoupled quiet artificial atoms

    PubMed Central

    Zagoskin, Alexandre M.; Chipouline, Arkadi; Il’ichev, Evgeni; Johansson, J. Robert; Nori, Franco

    2015-01-01

    The requirements of quantum computations impose high demands on the level of qubit protection from perturbations; in particular, from those produced by the environment. Here we propose a superconducting flux qubit design that is naturally protected from ambient noise. This decoupling is due to the qubit interacting with the electromagnetic field only through its toroidal moment, which provides an unusual qubit-field interaction, which is suppressed at low frequencies. PMID:26607667

  8. Radial Eigenmodes for a Toroidal Waveguide with Rectangular Cross Section

    SciTech Connect

    Rui Li

    2012-07-01

    In applying mode expansion to solve the CSR impedance for a section of toroidal vacuum chamber with rectangular cross section, we identify the eigenvalue problem for the radial eigenmodes which is different from that for cylindrical structures. In this paper, we present the general expressions of the radial eigenmodes, and discuss the properties of the eigenvalues on the basis of the Sturm-Liouville theory.

  9. Toroidal constant-tension superconducting magnetic energy storage units

    DOEpatents

    Herring, J. Stephen

    1992-01-01

    A superconducting magnetic energy storage unit is provided in which the magnet is wound in a toroidal fashion such that the magnetic field produced is contained only within the bore of the magnet, and thus producing a very low external field. The superconducting magnet includes a coolant channel disposed through the wire. The bore of the magnet comprises a storage volume in which cryogenic coolant is stored, and this volume supplies the coolant to be delivered to the coolant channel in the magnet.

  10. Nanospheres, nanotubes, toroids, and gels with controlled macroscopic chirality.

    PubMed

    Arias, Sandra; Freire, Félix; Quiñoá, Emilio; Riguera, Ricardo

    2014-12-01

    The interaction of a highly dynamic poly(aryl acetylene) (poly-1) with Li(+), Na(+), and Ag(+) leads to macroscopically chiral supramolecular nanospheres, nanotubes, toroids, and gels. With Ag(+), nanospheres with M helicity and tunable sizes are generated, which complement those obtained from the same polymer with divalent cations. With Li(+) or Na(+), poly-1 yields chiral nanotubes, gels, or toroids with encapsulating properties and M helicity. Right-handed supramolecular structures can be obtained by using the enantiomeric polymer. The interaction of poly-1 with Na(+) produces nanostructures whose helicity is highly dependent on the solvation state of the cation. Therefore, structures with either of the two helicities can be prepared from the same polymer by manipulation of the cosolvent. Such chiral nanotubes, toroids, and gels have previously not been obtained from helical polymer-metal complexes. Chiral nanospheres made of poly(aryl acetylene) that were previously assembled with metal(II) species can now be obtained with metal(I) species. PMID:25209219

  11. Expansions of non-symmetric toroidal magnetohydrodynamic equilibria

    NASA Astrophysics Data System (ADS)

    Weitzner, Harold

    2016-06-01

    Expansions of non-symmetric toroidal ideal magnetohydrodynamic equilibria with nested flux surfaces are carried out for two cases. The first expansion is in a topological torus in three dimensions, in which physical quantities are periodic of period 2 π in y and z. Data is given on the flux surface x = 0. Despite the possibility of magnetic resonances the power series expansion can be carried to all orders in a parameter which measures the flux between x = 0 and the surface in question. Resonances are resolved by appropriate addition resonant fields, as by Weitzner, [Phys. Plasmas 21, 022515 (2014)]. The second expansion is about a circular magnetic axis in a true torus. It is also assumed that the cross section of a flux surface at constant toroidal angle is approximately circular. The expansion is in an analogous flux coordinate, and despite potential resonance singularities, may be carried to all orders. Non-analytic behavior occurs near the magnetic axis. Physical quantities have a finite number of derivatives there. The results, even though no convergence proofs are given, support the possibility of smooth, well-behaved non-symmetric toroidal equilibria.

  12. Neoclassical offset toroidal velocity and auxiliary ion heating in tokamaks

    NASA Astrophysics Data System (ADS)

    Lazzaro, E.

    2016-05-01

    In conditions of ideal axisymmetry, for a magnetized plasma in a generic bounded domain, necessarily toroidal, the uniform absorption of external energy (e.g., RF or any isotropic auxiliary heating) cannot give rise to net forces or torques. Experimental evidence on contemporary tokamaks shows that the near central absorption of RF heating power (ICH and ECH) and current drive in presence of MHD activity drives a bulk plasma rotation in the co- I p direction, opposite to the initial one. Also the appearance of classical or neoclassical tearing modes provides a nonlinear magnetic braking that tends to clamp the rotation profile at the q-rational surfaces. The physical origin of the torque associated with P RF absorption could be due the effects of asymmetry in the equilibrium configuration or in power deposition, but here we point out also an effect of the response of the so-called neoclassical offset velocity to the power dependent heat flow increment. The neoclassical toroidal viscosity due to internal magnetic kink or tearing modes tends to relax the plasma rotation to this asymptotic speed, which in absence of auxiliary heating is of the order of the ion diamagnetic velocity. It can be shown by kinetic and fluid calculations, that the absorption of auxiliary power by ions modifies this offset proportionally to the injected power thereby forcing the plasma rotation in a direction opposite to the initial, to large values. The problem is discussed in the frame of the theoretical models of neoclassical toroidal viscosity.

  13. Modeling and analysis of silicon-embedded MEMS toroidal inductors

    NASA Astrophysics Data System (ADS)

    Araghchini, M.; Lang, J. H.

    2013-12-01

    This paper presents the modeling and analysis of three-dimensional silicon-embedded toroidal inductors designed for power converter applications. Special attention is given to modeling phenomena associated with the presence of silicon, namely an increase in loss and parasitic capacitance. Silicon-embedded inductors can be fabricated with silicon inside the donut-shaped toroidal core and inside the donut hole, as well as with silicon above, below and outside the inductor. It is argued here that, with the exception of the losses in the core at high doping densities, the losses in the silicon can be tolerated in many power applications, making fully-integrated silicon-embedded air-core inductors viable for power applications. An equivalent circuit model is presented for such inductors which captures the stored magnetic energy, the parasitic electric energy stored between the windings and the silicon, the loss in the toroidal windings, and the electrically- and magnetically-driven losses inside the silicon. The model developed here is verified against experimental data, and the comparison shows a good match over the frequency range of interest to power electronics applications.

  14. Connection formula for banana-drift neoclassical toroidal viscosity

    NASA Astrophysics Data System (ADS)

    Cole, A. J.; Hegna, C. C.; Callen, J. D.

    2010-11-01

    Non-resonant magnetic perturbations can affect plasma rotation in toroidally confined plasmas through their modification to |B|. Variations along a field line induce nonambipolar radial transport and produce a global neoclassical toroidal viscous force [NTV]. In this work, a previously calculated WKB-type solution smoothly connecting the low-collisionality ``1/ν'' and ``ν-√ν'' regimes is extended to include the superbanana plateau [sbp] regime [1]. The sbp effect occurs for particles whose toroidal ExB precessional drift vanishes. In this case, the relevant drift kinetic equation exhibits a ``turning point'' and the WKB method fails. We employ the connection formula method of Langer [2] which continuously varies between the previous WKB result and the superbanana regime without difficultly at the turning point. The resultant smoothed NTV is presented in terms of flows along flux surfaces. [4pt] [1] K. C. Shaing, S. A. Sabbagh, and M. S. Chu, PPCF 51, 035009 (2009), and refs. cited therein. [0pt] [2] R. E. Langer, Phys. Rev. 51, 669 (1937).

  15. Finite beta plasma equilibrium in toroidally linked mirrors

    SciTech Connect

    Ilgisonis, V.I.; Berk, H.L.; Pastukhov, V.P.

    1993-07-01

    The problem of finite pressure plasma equilibrium in a system with closed magnetic field lines consisting of quadrupole mirrors linked by simple toroidal cells with elliptical cross-sections is analyzed. An appropriate analytical procedure is developed, that uses conformal mapping techniques, which enables one to obtain the magnetic field structure for the free boundary equilibrium problem. This method has general applicability for finding analytic solutions of the two-dimensional Dirichlet problem outside of an arbitrary closed contour. Using this method, the deformations of the plasma equilibrium configuration due to finite plasma pressure in the toroidal cell are calculated analytically to the second order in {lambda}-expansion, where {lambda} {approximately} {beta}/{epsilon}E, {beta} is the ratio of plasma pressure to the magnetic field pressure, {epsilon} is the inverse aspect ratio and E is the ellipticity of the plasma cross-section. The outer displacement of the plasma column is shown to depend nonlinearly on the increase of plasma pressure, and does not prevent the achievement of substantial {beta} {approximately} 10% in the toroidal cells.

  16. Twisted toroidal vortex solitons in inhomogeneous media with repulsive nonlinearity.

    PubMed

    Kartashov, Yaroslav V; Malomed, Boris A; Shnir, Yasha; Torner, Lluis

    2014-12-31

    Toroidal modes in the form of so-called Hopfions, with two independent winding numbers, a hidden one (twist s), which characterizes a circular vortex thread embedded into a three-dimensional soliton, and the vorticity around the vertical axis (m), appear in many fields, including field theory, ferromagnetics, and semi- and superconductors. Such topological states are normally generated in multicomponent systems, or as trapped quasilinear modes in toroidal potentials. We uncover that stable solitons with this structure can be created, without any linear potential, in the single-component setting with the strength of repulsive nonlinearity growing fast enough from the center to the periphery, for both steep and smooth modulation profiles. Toroidal modes with s=1 and vorticity m=0, 1, 2 are produced. They are stable for m≤1, and do not exist for s>1. An approximate analytical solution is obtained for the twisted ring with s=1, m=0. Under the application of an external torque, it rotates like a solid ring. The setting can be implemented in a Bose-Einstein condensate (BEC) by means of the Feshbach resonance controlled by inhomogeneous magnetic fields. PMID:25615341

  17. Impact of plasma poloidal rotation on resistive wall mode instability in toroidally rotating plasmas

    SciTech Connect

    Aiba, N.; Shiraishi, J.; Tokuda, S.

    2011-02-15

    Stability of resistive wall mode (RWM) is investigated in a cylindrical plasma and an axisymmetric toroidal plasma by taking into account not only toroidal rotation but also poloidal rotation. Since the Doppler shifted frequency is responsible for the RWM stability, the modification of this Doppler shifted frequency by poloidal rotation affects the rotation effect on RWM. When a poloidal rotation frequency is not so large, the effect of poloidal rotation on the RWM stability can be approximately treated with the modified toroidal rotation frequency. In a toroidal plasma, this modified frequency is determined by subtracting a toroidal component of the rotation parallel to the magnetic field from the toroidal rotation frequency. The poloidal rotation that counteracts the effect of the Doppler shift strongly reduces the stabilizing effect of toroidal rotation, but by changing the rotational direction, the poloidal rotation enhances this stabilizing effect. This trend is confirmed in not only a cylindrical plasma but also a toroidal plasma. This result indicates that poloidal rotation produces the dependence of the critical toroidal rotation frequency for stabilizing RWM on the rotational direction of toroidal rotation in the same magnetic configuration.

  18. T cell-derived Act1 is necessary for IL-25-mediated Th2 responses and allergic airway inflammation.

    PubMed

    Swaidani, Shadi; Bulek, Katarzyna; Kang, Zizhen; Gulen, Muhammet Fatih; Liu, Caini; Yin, Weiguo; Abbadi, Amina; Aronica, Mark; Li, Xiaoxia

    2011-09-15

    The cellular and molecular mechanisms driven by IL-25 and its cognate receptor IL-17RB necessary for the promotion of Th2-mediating pathogenic pulmonary inflammation remains to be defined. We have previously reported the critical role of the U-box-type E3 ubiquitin ligase Act1 (1) for the downstream signaling of the IL-17 cytokine family including the Th2-promoting cytokine IL-25 (IL-17E) (2). In this study, we report that IL-25-driven but not conventional IL-4-driven Th2 polarization and cytokine production is impaired in Act1-deficient T cells. Also, Act1 deficiency in the T cell compartment results in the abrogation of eosinophilic airway infiltration as well as airway hyperresponsiveness in mouse models of Ag-induced airway inflammation. The in vivo generation of Ag-specific Th2 cytokine-producing cells is defective in the absence of Act1 expression in T cells after OVA/aluminum hydroxide immunization. Notably, the production of OVA-specific IgG(1) but not IgG(2a) or IgE is also impaired. At the molecular level, we report that IL-25-mediated induction of Th2 master regulator GATA-3 and the transcription factor GFI-1 is attenuated in Act1-deficient T cells. Taken together, our findings indicate that Act1 expression in T cells is required for cellular and humoral Th2-mediated allergic responses and the development of airway hyperresponsiveness, in part, through Act1's function in IL-25-induced development of Th2 T cells. PMID:21856933

  19. Poloidal field amplification in a coaxial compact toroid accelerator

    NASA Astrophysics Data System (ADS)

    Horton, R. D.; Hwang, D. Q.; Howard, S.; Brockington, S. J.; Evans, R. W.

    2008-09-01

    The Compact Toroid Injection Experiment (CTIX) produces spheromak-like compact toroids (SCTs) without external power switching, initiating a discharge by pulsed gas injection into a formation region containing a seed magnetic field generated by a solenoidal coil. After formation, the plasma is driven by an inductively delayed capacitor bank into an acceleration region, where surface axial and toroidal magnetic fields are measured at several axial positions. Due to strong eddy-current effects, formation-region magnetic field cannot be simply computed; instead, it is measured using the response of axial and radial test coils in the formation region to short solenoid test current pulses. A temporal and spatial reconstruction method is developed allowing formation-region field to be computed from the test-coil data for any CTIX discharge of identical solenoid geometry. By varying the peak value and timing of solenoidal current, curves of peak accelerator-region field as a function of initial formation-region field are developed. Curves of peak accelerator-region axial magnetic field are thereby found to be highly nonlinear functions of formation-region field, showing a threshold value for the formation-region field of approximately 5 G, above which acceleration-region field saturates at values between 2 and 12 kG. The direction of acceleration-region axial field reverses sign when the direction of solenoid current is reversed. Saturated accelerator-region axial field is a function of axial position and accelerator voltage, and is typically comparable to toroidal field at the same location. The ratio of accelerator-region to formation-region axial field commonly exceeds 1000 near the onset of saturation. This large amplification is of practical advantage for delayed plasma breakdown on CTIX, allowing a modest seed field to produce high poloidal fields, which are necessary for intense SCT acceleration. The results may also provide a useful benchmark for numerical

  20. Toroidal cell and battery. [storage battery for high amp-hour load applications

    NASA Technical Reports Server (NTRS)

    Nagle, W. J. (Inventor)

    1981-01-01

    A toroidal storage battery designed to handle relatively high amp-hour loads is described. The cell includes a wound core disposed within a pair of toroidal channel shaped electrodes spaced apart by nylon insulator. The shape of the case electrodes of this toroidal cell allows a first planar doughnut shaped surface and the inner cylindrical case wall to be used as a first electrode and a second planar doughnut shaped surface and the outer cylindrical case wall to be used as a second electrode. Connectors may be used to stack two or more toroidal cells together by connecting substantially the entire surface area of the first electrode of a first cell to substantially the entire surface area of the second electrode of a second cell. The central cavity of each toroidal cell may be used as a conduit for pumping a fluid through the toroidal cell to thereby cool the cell.

  1. First-principles approach to investigate toroidal property of magnetoelectric multiferroic GaFeO3

    NASA Astrophysics Data System (ADS)

    Nie, Yung-mau

    2016-01-01

    A first-principles approach incorporating the concept of toroidal moments as a measure of the spin vortex is proposed and applied to simulate the toroidization of magnetoelectric multiferroic GaFeO3. The nature of space-inversion and time-reversal violations of ferrotoroidics is reproduced in the simulated magnetic structure of GaFeO3. For undoped GaFeO3, a toroidal moment of -22.38 μB Å per unit cell was obtained, which is the best theoretical estimate till date. Guided by the spin vortex free-energy minimization perturbed by an externally applied field, it was discovered that the minority spin markedly biases the whole toroidization. In summary, this approach not only calculates the toroidal moment but provides a way to understand the toroidal nature of magnetoelectric multiferroics.

  2. Electrical and mechanical design report of the muon toroids for the beamline to the muon laboratory

    SciTech Connect

    Visser, A.; Western, J.; Skraboly, A.

    1987-03-01

    This report describes two large steel toroids used to remove beam halo for experiment 665. One toroid is 88 inch diameter and 30 feet long. The other is 120 inch diameter and 20 feet long. Both have a 7 inch diameter center hole for passage of the beam and the excitation windings. The assembled hybrid coil has water-cooled conductors in the center hole and cables on the outside. This permits the use of one piece steel plates through which the center core is inserted after assembly of the toroid steel. These toroids have advantages over conventional toroids in many aspects. The main ones being its reduced power consumption, simplicity of machining and assembly, and lower coil costs. Estimates of the induction and a simple method to buck the remnant magnetic field are included. The bucking method does not completely degauss all the toroid steel.

  3. Elmo bumpy square plasma confinement device

    DOEpatents

    Owen, L.W.

    1985-01-01

    The invention is an Elmo bumpy type plasma confinement device having a polygonal configuration of closed magnet field lines for improved plasma confinement. In the preferred embodiment, the device is of a square configuration which is referred to as an Elmo bumpy square (EBS). The EBS is formed by four linear magnetic mirror sections each comprising a plurality of axisymmetric assemblies connected in series and linked by 90/sup 0/ sections of a high magnetic field toroidal solenoid type field generating coils. These coils provide corner confinement with a minimum of radial dispersion of the confined plasma to minimize the detrimental effects of the toroidal curvature of the magnetic field. Each corner is formed by a plurality of circular or elliptical coils aligned about the corner radius to provide maximum continuity in the closing of the magnetic field lines about the square configuration confining the plasma within a vacuum vessel located within the various coils forming the square configuration confinement geometry.

  4. The vector potential of a circular cylindrical antenna in terms of a toroidal harmonic expansion

    NASA Astrophysics Data System (ADS)

    Selvaggi, Jerry; Salon, Sheppard; Chari, M. V. K.

    2008-08-01

    A toroidal harmonic expansion is developed which is used to represent the vector potential due to a circular cylindrical antenna with a rectangular cross section at any arbitrary point in space. The singular part of the antenna kernel is represented by an associated toroidal harmonic expansion and the analytic part of the kernel is represented by a binomial expansion. A simple example is given to illustrate the application of the toroidal expansion.

  5. Toroidal spiral Nambu-Goto strings around higher-dimensional black holes

    SciTech Connect

    Igata, Takahisa; Ishihara, Hideki

    2010-08-15

    We present solutions of the Nambu-Goto equation for test strings in a shape of toroidal spiral in five-dimensional spacetimes. In particular, we show that stationary toroidal spirals exist around the five-dimensional Myers-Perry black holes. We also show the existence of innermost stationary toroidal spirals around the five-dimensional black holes like geodesic particles orbiting around four-dimensional black holes.

  6. PARTICLE-HOLE NATURE OF THE LIGHT HIGH-SPIN TOROIDAL ISOMERS

    SciTech Connect

    Staszczak, A.; Wong, Cheuk-Yin

    2015-01-01

    Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme Hartree Fock approach that even even, N = Z, high-K, toroidal isomeric states may have general occurrences for light nuclei with 28 < A < 52. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

  7. The fabrication of toroidal and coma-corrected toroidal diffraction gratings from spherical master gratings using elastically-deformable substrates - A progress report

    NASA Technical Reports Server (NTRS)

    Huber, Martin C. E.; Timothy, J. G.; Morgan, Jeffrey S.; Lemaitre, Gerard; Tondello, Giuseppe; Naletto, Giampiero

    1991-01-01

    A technique has been developed which permits toroidal, and coma-corrected toroidal, diffraction gratings to be replicated from spherical master gratings by the use of elastically-deformable substrates. Toroidal gratings correct for astigmatism and, thus, make it possible to construct stigmatic spectrometers that employ a single reflective diffraction grating. These spectrometers are particularly useful for the extreme-ultraviolet (EUV) wavelength range, where reflection coefficients are low, since the single optical surface provides for dispersion, focusing, and astigmatism correction. The fabrication procedures for the pure toroidal, and coma-corrected toroidal, gratings are described, and initial test results are presented. The use of the toroidal gratings in a high-resolution sounding-rocket EUV spectroheliometer, and in both the coronal diagnostics spectrometer and the ultraviolet coronagraph spectrometer on the ESA/NASA solar and heliospheric observatory mission, is described briefly, and the use of this technique for the fabrication of a coma-corrected toroidal grating for the prime Rowland spectrograph of the FUSE/Lyman mission is briefly discussed.

  8. Self-Assembly and Tissue Fusion of Toroid-Shaped Minimal Building Units

    PubMed Central

    Livoti, Christine M.

    2010-01-01

    A significant challenge of tissue engineering is to build tissues whose size is not limited by diffusion. We are investigating the use of scaffold-free lumen containing toroid-shaped microtissues as minimal building units. Monodispersed H35 cells, a rat hepatocyte cell line, were seeded onto micromolded agarose, forming self-assembled multicellular toroids within 48 h. Toroid and lumen diameter were easily controlled by micromold design, and toroid thickness was controlled by seeding density. When harvested, toroids were stable, but underwent predictable changes over time with their lumens narrowing. When brought into contact, these building units fused in the x–y plane, forming a double-lumen structure, as well as the z plane, forming a tubular structure, which completed within 72 h. Large, multi-luminal structures were assembled by multidimensional fusion of many toroids. Toroid settling was not entirely random, with most toroids lying flat with their lumens oriented along the z axis. The rapid production of toroid building units of controlled dimension and lumen size that undergo predictable changes and that can be fused to form larger structures is a step closer to tissue engineering large porous three-dimensional tissues with high cell density. PMID:20109063

  9. Thermal Ablation by High-Intensity-Focused Ultrasound Using a Toroid Transducer Increases the Coagulated Volume and Allows Coagulation Near Portal and Hepatic veins in Pigs

    SciTech Connect

    Melodelima, D.; N'Djin, W. A.; Parmentier, H.; Chapelon, J. Y.; Rivoire, M.

    2009-04-14

    A new geometry of HIFU transducer is described to enlarge the coagulated volume. The geometry of the transducer was not spherical. The surface of the transducer was built based on a toroid geometry. The transducer was generated by the revolution of a circle about an axis lying in its plane. Eight emitters operating at a frequency of 3 MHz were diced out of a single toroid piezocomposite element. Each of the eight emitters was divided into 32 transducers. The focal zone is conical and located at 70 mm from the transducer. A 7.5 MHz ultrasound imaging probe is placed in the centre of the device for guiding the treatment. Our long-term objective is to develop a device that can be used during surgery. In vivo trials have been performed on 13 pigs to demonstrate this new principle and to evaluate the vascular tolerance of the treatment. This new geometry combined with consecutive activation of the eight emitters around the toroid allows achieving a mean thermal ablation of 7.0{+-}2.5 cm3 in 40 seconds. All lesions were visible with high contrast on sonograms. The correlation between the size of lesions observed on sonograms and during gross examination was 92%. This allows the user to easily enlarge the coagulated volume by juxtaposing single lesions. The pigs tolerate the treatment well over the experimental period even when coagulation was produced through portal and/or hepatic veins.

  10. Edge magnetohydrodynamic instability studies in the Pegasus Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Bongard, Michael W.

    Peeling modes, an instability mechanism underlying deleterious Edge Localized Mode (ELM) activity in fusion-grade plasmas, are observed at the plasma edge in the PEGASUS Toroidal Experiment under conditions of high edge current density (Jedge(˜ 0.1 MA/m2) and low magnetic field (B ˜0.1 T) present at near-unity aspect ratio. Their macroscopic properties are measured using external Mirnov coil arrays, Langmuir probes, and high-speed visible imaging. The modest edge parameters and short pulse lengths of PEGASUS discharges permit direct measurement of the internal magnetic field structure with an insertable array of Hall-effect sensors, providing the current profile and its dynamical evolution on ELM-relevant timescales. Peeling modes generate coherent, edge-localized electromagnetic activity with low toroidal mode numbers n ≤ 3 and high poloidal mode numbers, in agreement with theoretical expectations of a low- n external kink structure. Coherent MHD fluctuation amplitudes are found to be strongly dependent on the experimentally measured J edge/B peeling instability drive, consistent with theory. An equilibrium reconstruction obtained during peeling activity with its current profile constrained by internal Hall measurements is used to test the predictions of analytic peeling stability theory and the ideal MHD stability model. Both approaches are in agreement with experiment, with the latter finding instability to an external kink. Peeling modes nonlinearly generate ELM-like, field-aligned filamentary structures. They detach from the edge and transiently accelerate radially outward, followed by propagation with constant velocity. Time-resolved Jedge measurements demonstrate that the filaments are formed from an initial current-hole perturbation and carry net toroidal currents If ˜ 100--200 A, less than 0.2% of the plasma current. Their constant-velocity radial motions are in qualitative agreement with rates given by electromagnetic blob transport theory.

  11. On steady poloidal and toroidal flows in tokamak plasmas

    SciTech Connect

    McClements, K. G.

    2010-08-15

    The effects of poloidal and toroidal flows on tokamak plasma equilibria are examined in the magnetohydrodynamic limit. ''Transonic'' poloidal flows of the order of the sound speed multiplied by the ratio of poloidal magnetic field to total field B{sub {theta}/}B can cause the (normally elliptic) Grad-Shafranov (GS) equation to become hyperbolic in part of the solution domain. It is pointed out that the range of poloidal flows for which the GS equation is hyperbolic increases with plasma beta and B{sub {theta}/}B, thereby complicating the problem of determining spherical tokamak plasma equilibria with transonic poloidal flows. It is demonstrated that the calculation of the hyperbolicity criterion can be easily modified when the assumption of isentropic flux surfaces is replaced with the more tokamak-relevant one of isothermal flux surfaces. On the basis of the latter assumption, a simple expression is obtained for the variation of density on a flux surface when poloidal and toroidal flows are simultaneously present. Combined with Thomson scattering measurements of density and temperature, this expression could be used to infer information on poloidal and toroidal flows on the high field side of a tokamak plasma, where direct measurements of flows are not generally possible. It is demonstrated that there are four possible solutions of the Bernoulli relation for the plasma density when the flux surfaces are assumed to be isothermal, corresponding to four distinct poloidal flow regimes. Finally, observations and first principles-based theoretical modeling of poloidal flows in tokamak plasmas are briefly reviewed and it is concluded that there is no clear evidence for the occurrence of supersonic poloidal flows.

  12. Alpha particle destabilization of the toroidicity-induced Alfven eigenmodes

    SciTech Connect

    Cheng, C.Z.

    1990-10-01

    The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped {alpha}-particles through the wave-particle resonances. Satisfying the resonance condition requires that the {alpha}-particle birth speed v{sub {alpha}} {ge} v{sub A}/2{vert bar}m-nq{vert bar}, where v{sub A} is the Alfven speed, m is the poloidal model number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the {alpha}-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the {alpha}-particles and the core electrons and ions. The growth rate was studied analytically with a perturbative formula derived from the quadratic dispersion relation, and numerically with the aid of the NOVA-K code. Stability criteria in terms of the {alpha}-particle beta {beta}{sub {alpha}}, {alpha}-particle pressure gradient parameter ({omega}{sub {asterisk}}/{omega}{sub A}) ({omega}{sub {asterisk}} is the {alpha}-particle diamagnetic drift frequency), and (v{sub {alpha}}/v{sub A}) parameters will be presented for TFTR, CIT, and ITER tokamaks. The volume averaged {alpha}-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged {alpha}-particle beta threshold is in the order of 10{sup {minus}4}. Typical growth rates of the n=1 TAE mode can be in the order of 10{sup {minus}2}{omega}{sub A}, where {omega}{sub A}=v{sub A}/qR. Other types of global Alfven waves are stable in D-T tokamaks due to toroidal coupling effects.

  13. Observation of Central Toroidal Rotation Induced by ICRF on EAST

    NASA Astrophysics Data System (ADS)

    Pan, Xiayun; Wang, Fudi; Zhang, Xinjun; Lyu, Bo; Chen, Jun; Li, Yingying; Fu, Jia; Shi, Yuejiang; Yu, Yi; Ye, Minyou; Wan, Baonian

    2016-02-01

    Core plasma rotation of both L-mode and H-mode discharges with ion cyclotron range of frequency (ICRF) minority heating (MH) scheme was measured with a tangential X-ray imaging crystal spectrometer on EAST (Experimental Advanced Superconducting Tokamak). Co-current central impurity toroidal rotation change was observed in ICRF-heated L- and H-mode plasmas. Rotation increment as high as 30 km/s was generated at ∼1.7 MW ICRF power. Scaling results showed similar trend as the Rice scaling but with significant scattering, especially in L-mode plasmas. We varied the plasma current, toroidal field and magnetic configuration individually to study their effect on L-mode plasma rotation, while keeping the other major plasma parameters and heating unchanged during the scanning. It was found that larger plasma current could induce plasma rotation more efficiently. A scan of the toroidal magnetic field indicated that the largest rotation was obtained for on-axis ICRF heating. A comparison between lower-single-null (LSN) and double-null (DN) configurations showed that LSN discharges rendered a larger rotation change for the same power input and plasma parameters. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB112004 and 2015GB103002), National Natural Science Foundation of China (Nos. 11175208, 11305212, 11375235, 11405212 and 11261140328), the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology (2014FXCX003) and Brain Korea 21 Program for Leading Universities & Students (BK21 PLUS)

  14. Free-boundary toroidal Alfvén eigenmodes

    NASA Astrophysics Data System (ADS)

    Chen, Eugene Y.; Berk, H. L.; Breizman, B.; Zheng, L. J.

    2011-05-01

    A numerical study is presented for the n = 1 free-boundary toroidal Alfvén eigenmodes (TAE) in tokamaks, which shows that there is considerable sensitivity of n = 1 modes to the position of the conducting wall. An additional branch of the TAE is shown to emerge from the upper continuum as the ratio of conducting wall radius to plasma radius increases. Such phenomena arise in plasma equilibria with both circular and shaped cross sections, where the shaped profile studied here is similar to that found in Alcator C-Mod.

  15. Resistive demountable toroidal-field coils for tokamak reactors

    SciTech Connect

    Jassby, D.L.; Jacobsen, R.A.; Kalnavarns, J.; Masson, L.S.; Sekot, J.P.

    1981-07-01

    Readily demountable TF (toroidal-field) coils allow complete access to the internal components of a tokamak reactor for maintenance of replacement. The requirement of readily demountable joints dictates the use of water-cooled resistive coils, which have a host of decisive advantages over superconducting coils. Previous papers have shown that resistive TF coils for tokamak reactors can operate in the steady state with acceptable power dissipation (typically, 175 to 300 MW). This paper summarizes results of parametric studies of size optimization of rectangular TF coils and of a finite-element stress analysis, and examines several candidate methods of implementing demountable joints for rectangular coils constructed of plate segments.

  16. Toroidal transformer design program with application to inverter circuitry

    NASA Technical Reports Server (NTRS)

    Dayton, J. A., Jr.

    1972-01-01

    Estimates of temperature, weight, efficiency, regulation, and final dimensions are included in the output of the computer program for the design of transformers for use in the basic parallel inverter. The program, written in FORTRAN 4, selects a tape wound toroidal magnetic core and, taking temperature, materials, core geometry, skin depth, and ohmic losses into account, chooses the appropriate wire sizes and number of turns for the center tapped primary and single secondary coils. Using the program, 2- and 4-kilovolt-ampere transformers are designed for frequencies from 200 to 3200 Hz and the efficiency of a basic transistor inverter is estimated.

  17. Evidence of Inward Toroidal Momentum Convection in the JET Tokamak

    SciTech Connect

    Tala, T.; Zastrow, K.-D.; Brix, M.; Corrigan, G.; Giroud, C.; Naulin, V.; Peeters, A. G.; Tardini, G.; Strintzi, D.

    2009-02-20

    Experiments have been carried out on the Joint European Torus tokamak to determine the diffusive and convective momentum transport. Torque, injected by neutral beams, was modulated to create a periodic perturbation in the toroidal rotation velocity. Novel transport analysis shows the magnitude and profile shape of the momentum diffusivity are similar to those of the ion heat diffusivity. A significant inward momentum pinch, up to 20 m/s, has been found. Both results are consistent with gyrokinetic simulations. This evidence is complemented in plasmas with internal transport barriers.

  18. Observation of odd toroidal Alfvén eigenmodes.

    PubMed

    Kramer, G J; Sharapov, S E; Nazikian, R; Gorelenkov, N N; Budny, R V

    2004-01-01

    Experimental evidence is presented for the existence of the theoretically predicted odd toroidicity induced Alfvén eigenmode (TAE) from the simultaneous appearance of odd and even TAEs in a normal shear discharge of the joint European torus. The modes are observed in low central magnetic shear plasmas created by injecting lower hybrid current drive. A fast ion population was created by applying ion cyclotron heating at the high-field side to excite the TAEs. The odd TAEs were identified from their frequency, mode number, and timing relative to the even TAEs. PMID:14753994

  19. Toroidally symmetric plasma vortex at tokamak divertor null point

    NASA Astrophysics Data System (ADS)

    Umansky, M. V.; Ryutov, D. D.

    2016-03-01

    Reduced MHD equations are used for studying toroidally symmetric plasma dynamics near the divertor null point. Numerical solution of these equations exhibits a plasma vortex localized at the null point with the time-evolution defined by interplay of the curvature drive, magnetic restoring force, and dissipation. Convective motion is easier to achieve for a second-order null (snowflake) divertor than for a regular x-point configuration, and the size of the convection zone in a snowflake configuration grows with plasma pressure at the null point. The trends in simulations are consistent with tokamak experiments which indicate the presence of enhanced transport at the null point.

  20. A flexible high-energy toroidal grating monochromator at Bessy

    SciTech Connect

    Bernstorff, S.; Braun, W.; Mast, M.; Peatman, W.; Schroeter, T.

    1989-07-01

    A toroidal grating monochromator, the HE-TGM-2, designed for medium high resolution and high transmission in the spectral range 100--730 eV, has been installed and tested at the Berlin electron storage ring BESSY. Having a conventional configuration, namely a prefocusing mirror and an entrance slit, the resolution of the HE-TGM-2 is essentially independent of the source size and position of the stored electron beam. Gas phase photoionization spectra of free atoms and molecules as well as photoemission experiments on solid surfaces have been used to characterize this monochromator.

  1. Toroidal equilibrium with low frequency wave driven currents

    SciTech Connect

    Ehst, D.A.

    1984-12-01

    In the absence of an emf the parallel current, j/sub parallel/, in a steady state tokamak will consist of a neoclassical portion plus a wave-driven contribution. Using the drift kinetic equation, the quasilinear (wave-driven) current is computed for high phase speed waves in a torus, and this is combined with the neoclassical term to obtain the general expression for the flux surface average . For a given pressure profile this technique fully determines the MHD equilibrium, permitting the study of a new class of toroidal equilibria.

  2. Effect of alpha particles on Toroidal Alfven Eigenmodes

    SciTech Connect

    Berk, H.L.

    1992-11-01

    An overview is given of the analytic structure for the linear theory of the Toroidal Alfven Eigenmode (TAE), where multiple gap structures occur. A discussion is given of the alpha particle drive and the various dissipation mechanisms that can stabilize the system. A self-consistent calculation of the TAE mode, for a low-beta high-aspect-ratio plasma, indicates that though the alpha particle drive is comparable to the dissipation mechanisms, overall stability is still achieved for ignited ITER-like plasma. A brief discussion is given of the nonlinear theory for the TAE mode and how nonlinear alpha particle dynamics can be treated by mapping methods.

  3. Theory and application of maximum magnetic energy in toroidal plasmas

    SciTech Connect

    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{prime}/q (as in reverse field pinches and spheromaks) to have the same {alpha} in all its force-free regions and with a positive q{prime}/q (as in tokamaks) to have centrally peaked {alpha}'s.

  4. Theory and application of maximum magnetic energy in toroidal plasmas

    SciTech Connect

    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{prime}/q (as in reverse field pinches and spheromaks) to have the same {alpha} in all its force-free regions and with a positive q{prime}/q (as in tokamaks) to have centrally peaked {alpha}`s.

  5. Simulation of dust streaming in toroidal traps: Stationary flows

    SciTech Connect

    Reichstein, Torben; Piel, Alexander

    2011-08-15

    Molecular-dynamic simulations were performed to study dust motion in a toroidal trap under the influence of the ion drag force driven by a Hall motion of the ions in E x B direction, gravity, inter-particle forces, and friction with the neutral gas. This article is focused on the inhomogeneous stationary streaming motion. Depending on the strength of friction, the spontaneous formation of a stationary shock or a spatial bifurcation into a fast flow and a slow vortex flow is observed. In the quiescent streaming region, the particle flow features a shell structure which undergoes a structural phase transition along the flow direction.

  6. Geodesic Acoustic Mode Induced by Toroidal Rotation in Tokamaks

    SciTech Connect

    Wahlberg, C.

    2008-09-12

    The effect of toroidal rotation on the geodesic acoustic mode (GAM) in a tokamak is studied. It is shown that, in addition to a small frequency upshift of the ordinary GAM, another GAM, with much lower frequency, is induced by the rotation. The new GAM appears as a consequence of the nonuniform plasma density and pressure created by the centrifugal force on the magnetic surfaces. Both GAMs in a rotating plasma are shown to exist both as continuum modes with finite mode numbers m and n at the rational surfaces q=m/n as well as in the form of axisymmetric modes with m=n=0.

  7. Atomic physics effects on dissipative toroidal drift wave stability

    SciTech Connect

    Beer, M.A.; Hahm, T.S.

    1992-02-01

    The effects of atomic physics processes such as ionization, charge exchange, and radiation on the linear stability of dissipative drift waves are investigated in toroidal geometry both numerically and analytically. For typical TFTR and TEXT edge parameters, overall linear stability is determined by the competition between the destabilizing influence of ionization and the stabilizing effect due to the electron temperature gradient. An analytical expression for the linear marginal stability condition, {eta}{sub e}{sup crit}, is derived. The instability is most likely to occur at the extreme edge of tokamaks with a significant ionization source and a steep electron density gradient.

  8. Position indicating split toroid for the RACE experiment

    NASA Astrophysics Data System (ADS)

    Hurst, B.; Folkman, K.

    2007-08-01

    Aspects of the recent reactor accelerator coupled experiments (RACE) carried out at the University of Texas Nuclear Engineering Teaching Laboratory will be discussed. In particular, a compact instrument that allowed a continuous non-invasive means of determining the relative electron beam position was developed. The operation of the instrument is similar to an inductive current pick up toroid except that the core is sectioned radially, which allows spatial information to be derived from the induced voltages. Results of initial tests, both in beam and with a pulser, will be presented along with plans to optimize future designs.

  9. Fabrication of toroidal composite pressure vessels. Final report

    SciTech Connect

    Dodge, W.G.; Escalona, A.

    1996-11-24

    A method for fabricating composite pressure vessels having toroidal geometry was evaluated. Eight units were fabricated using fibrous graphite material wrapped over a thin-walled aluminum liner. The material was wrapped using a machine designed for wrapping, the graphite material was impregnated with an epoxy resin that was subsequently thermally cured. The units were fabricated using various winding patterns. They were hydrostatically tested to determine their performance. The method of fabrication was demonstrated. However, the improvement in performance to weight ratio over that obtainable by an all metal vessel probably does not justify the extra cost of fabrication.

  10. Implications of polarized DT plasmas for toroidal fusion reactors

    SciTech Connect

    Micklich, B.J.; Jassby, D.L.

    1983-05-01

    Spin polarization of the deuterons and tritons in a reacting plasma can result in an increase in the fusion reactivity and variation of the angular distribution of emission of the fusion neutrons. The increased fusion reactivity relaxes the confinement-temperature conditions for breakeven and ignition. We have determined the effect of varying the angular distribution of the fusion neutrons on the spatial distribution of fusion neturon current and flux at the first wall, on the global tritium breeding ratio, and on the first-wall radiation damage in low-aspect-ratio toroidal geometry.

  11. Experimental observation of crystalline particle flows in toroidal dust clouds

    SciTech Connect

    Wilms, Jochen Piel, Alexander; Reichstein, Torben

    2015-06-15

    The dust flow in a toroidal dust trap is studied experimentally. The flow is driven by the Hall component of the ion drag force in a magnetized plasma. Dust density waves are found in a torus with a large minor radius a, which allows for several wavelength, 2a>5λ, in the (mostly) radial direction of the ion flow. Beyond an intermediate state with radial sloshing oscillations, a crystalline dust flow with suppressed wave activity could be realized for 2a<2λ. The particles arrange themselves in distinct layers with hexagonal-like local order. Smooth transitions between states with different numbers of layers are found in the inhomogeneous flow.

  12. Plastic Finite Element Analysis of D0 Toroid Iron Welds

    SciTech Connect

    Wands, R.; /Fermilab

    1987-11-23

    The assembly of the DO toroid iron involves the use of large groove welds to connect massive blocks of steel. These welds are very heavily constrained, and large thermal strains develop which have produced large cracks in the base metal near the weld. The effort to solve these problems has involved investigations of weld geometry, weld preparation, and the metallurgy of both the base metal and the welding rod. The purpose of this analysis was to compare the effects of two welding rods with markedly different yield strengths and post-yieding behaviour on the plastic strains developed in the base metal near the weld.

  13. Toroidal constant-tension superconducting magnetic energy storage units

    DOEpatents

    Herring, J.S.

    1992-11-03

    A superconducting magnetic energy storage unit is provided in which the magnet is wound in a toroidal fashion such that the magnetic field produced is contained only within the bore of the magnet, and thus producing a very low external field. The superconducting magnet includes a coolant channel disposed through the wire. The bore of the magnet comprises a storage volume in which cryogenic coolant is stored, and this volume supplies the coolant to be delivered to the coolant channel in the magnet. 6 figs.

  14. Hydraulic jumps in inhomogeneous strongly coupled toroidal dust flows

    NASA Astrophysics Data System (ADS)

    Piel, Alexander; Wilms, Jochen

    2016-07-01

    The inhomogeneous flow of strongly coupled dust particles in a toroidal particle trap with harmonic radial confinement is analyzed in the incompressible fluid limit. It is shown that the flow can spontaneously generate shock-like events, which are similar to the hydraulic jump in open channel flows. A definition of the Froude number for this model is given and the critical speed is recovered as the group velocity of surface waves. This hydraulic model is compared with molecular-dynamics simulations, which show that a sudden bifurcation of the flow lines and a localized temperature peak appear just at the point where the critical condition for the hydraulic jump is located.

  15. Properties of Alfvén eigenmodes in the Toroidal Alfvén Eigenmode range on the National Spherical Torus Experiment-Upgrade

    SciTech Connect

    Podestà, M.; Gorelenkov, N. N.; White, R. B.; Fredrickson, E. D.; Gerhardt, S. P.; Kramer, G. J.

    2013-08-15

    A second Neutral Beam (NB) injection line is being installed on the NSTX Upgrade device, resulting in six NB sources with different tangency radii that will be available for heating and current drive. This work explores the properties of instabilities in the frequency range of the Toroidal Alfvén Eigenmode (TAE) for NSTX-U scenarios with various NB injection geometries, from more perpendicular to more tangential, and with increased toroidal magnetic field with respect to previous NSTX scenarios. Predictions are based on analysis through the ideal MHD code NOVA-K. For the scenarios considered in this work, modifications of the Alfvén continuum result in a frequency up-shift and a broadening of the radial mode structure. The latter effect may have consequences for fast ion transport and loss. Preliminary stability considerations indicate that TAEs are potentially unstable with ion Landau damping representing the dominant damping mechanism.

  16. Toroidal modelling of RMP response in ASDEX Upgrade: coil phase scan, q 95 dependence, and toroidal torques

    NASA Astrophysics Data System (ADS)

    Liu, Yueqiang; Ryan, D.; Kirk, A.; Li, Li; Suttrop, W.; Dunne, M.; Fischer, R.; Fuchs, J. C.; Kurzan, B.; Piovesan, P.; Willensdorfer, M.; the ASDEX Upgrade Team; the EUROfusion MST1 Team

    2016-05-01

    The plasma response to the vacuum resonant magnetic perturbation (RMP) fields, produced by the ELM control coils in ASDEX Upgrade experiments, is computationally modelled using the MARS-F/K codes (Liu et al 2000 Phys. Plasmas 7 3681, Liu et al 2008 Phys. Plasmas 15 112503). A systematic investigation is carried out, considering various plasma and coil configurations as in the ELM control experiments. The low q plasmas, with {{q}95}∼ 3.8 (q 95 is the safety factor q value at 95% of the equilibrium poloidal flux), responding to low n (n is the toroidal mode number) field perturbations from each single row of the ELM coils, generates a core kink amplification effect. Combining two rows, with different toroidal phasing, thus leads to either cancellation or reinforcement of the core kink response, which in turn determines the poloidal location of the peak plasma surface displacement. The core kink response is typically weak for the n  =  4 coil configuration at low q, and for the n  =  2 configuration but only at high q ({{q}95}∼ 5.5 ). A phase shift of around 60 degrees for low q plasmas, and around 90 degrees for high q plasmas, is found in the coil phasing, between the plasma response field and the vacuum RMP field, that maximizes the edge resonant field component. This leads to an optimal coil phasing of about 100 (‑100) degrees for low (high) q plasmas, that maximizes both the edge resonant field component and the plasma surface displacement near the X-point of the separatrix. This optimal phasing closely corresponds to the best ELM mitigation observed in experiments. A strong parallel sound wave damping moderately reduces the core kink response but has minor effect on the edge peeling response. For low q plasmas, modelling shows that both the resonant electromagnetic torque and the neoclassical toroidal viscous (NTV) torque (due to the presence of 3D magnetic field perturbations) contribute to the toroidal flow damping, in particular near the

  17. REVIEW ARTICLE: Control of non-axisymmetric toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Boozer, Allen H.

    2010-10-01

    The control of non-axisymmetric toroidal plasmas, stellarators, has a different character than the control of tokamaks for two reasons. Non-axisymmetric magnetic fields (1) can provide an arbitrarily large fraction of the poloidal magnetic field and (2) can strongly center the plasma in the chamber making it impossible to lose position control. The focus of stellarator design is on plasmas that are stable without feedback, need little or no change in the external magnetic field as the plasma evolves, and require no external power to maintain the desired magnetic configuration. The physics of non-axisymmetric fields is the same whether in a tokamak or a stellarator and whether introduced intentionally or accidentally. Fundamental physics indicates that plasma shape, which is controlled by the distribution of the external magnetic field that is normal to the plasma surface, is the primary control for fusion plasmas. The importance of non-axisymmetric control is set by the importance of toroidal plasma physics. Informed decisions on the development strategy of tokamaks, as well as magnetic fusion in general, require an understanding of the capabilities and difficulties of plasma control at various levels of non-axisymmetric shaping.

  18. Toroidal magnetic confinement of non-neutral plasmas

    SciTech Connect

    Yoshida, Zensho; Ogawa, Yuichi; Morikawa, Junji; Himura, Haruhiko; Kondo, Shigeo; Nakashima, Chihiro; Kakuno, Shuichi; Iqbal, Muhamad; Volponi, Francesco; Shibayama, Norihisa; Tahara, Shigeru

    1999-12-10

    A new method of toroidal non-neutral plasma trap has been developed with applying the chaos-induced radial transport of particles near a magnetic null point. A pure electron plasma is produced by injecting an electron beam. The poloidal gyroradius of an electron at the energy of 1 keV is of order 10 mm, which determines the length scale of the chaotic region. Amongst various applications of toroidal non-neutral plasmas, a possibility of producing very high-{beta} plasma, which is suitable for advanced fusion, has been examined. The self-electric field of a non-neutral plasma can generate a strong shear flow. When the flow velocity is comparable to the Alfven speed (which is smaller than the ion sound speed, if {beta}>1), a high-{beta} equilibrium can be produced in which the plasma pressure is primarily balanced by the dynamic pressure of the flow. This configuration is described by a generalized Bernoulli law.

  19. Toroidal Magnetic Confinement of Non-Neutral Plasmas

    SciTech Connect

    Zensho Yoshida; Yuichi Ogawa; Junji Morikawa; Haruhiko Himura; Shigeo Kondo; Chihiro Nakashima; Shuichi Kakuno; Muhamad Iqbal; Francesco Volponi; Norihisa Shibayama; Shigeru Tahara

    1999-12-31

    A new method of toroidal non-neutral plasma trap has been developed with applying the chaos-induced radial transport of particles near a magnetic null point. A pure electron plasma is produced by injecting an electron beam. The poloidal gyro-radius of an electron at the energy of 1 keV is of order 10 mm, which determines the length scale of the chaotic region. Amongst various applications of toroidal non-neutral plasmas, a possibility of producing very high-{beta} plasma, which is suitable for advanced fusion, has been examined. The self-electric field of a non-neutral plasma can generate a strong shear flow. When the flow velocity is comparable to the Alfven speed (which is smaller than the ion sound speed, if {beta} > 1), a high-{beta} equilibrium can be produced in which the plasma pressure is primarily balanced by the dynamic pressure of the flow. This configuration is described by a generalized Bernoulli law.

  20. On the toroidal plasma rotations induced by lower hybrid waves

    SciTech Connect

    Guan Xiaoyin; Fisch, Nathaniel J.; Qin Hong; Liu Jian

    2013-02-15

    A theoretical model is developed to explain the plasma rotations induced by lower hybrid waves in Alcator C-Mod. In this model, torodial rotations are driven by the Lorentz force on the bulk-electron flow across flux surfaces, which is a response of the plasma to the resonant-electron flow across flux surfaces induced by the lower hybrid waves. The flow across flux surfaces of the resonant electrons and the bulk electrons are coupled through the radial electric field initiated by the resonant electrons, and the friction between ions and electrons transfers the toroidal momentum to ions from electrons. An improved quasilinear theory with gyrophase dependent distribution function is developed to calculate the perpendicular resonant-electron flow. Toroidal rotations are determined using a set of fluid equations for bulk electrons and ions, which are solved numerically by a finite-difference method. Numerical results agree well with the experimental observations in terms of flow profile and amplitude. The model explains the strong correlation between torodial flow and internal inductance observed experimentally, and predicts both counter-current and co-current flows, depending on the perpendicular wave vectors of the lower hybrid waves.

  1. Pole-phase modulated toroidal winding for an induction machine

    DOEpatents

    Miller, John Michael; Ostovic, Vlado

    1999-11-02

    A stator (10) for an induction machine for a vehicle has a cylindrical core (12) with inner and outer slots (26, 28) extending longitudinally along the inner and outer peripheries between the end faces (22, 24). Each outer slot is associated with several adjacent inner slots. A plurality of toroidal coils (14) are wound about the core and laid in the inner and outer slots. Each coil occupies a single inner slot and is laid in the associated outer slot thereby minimizing the distance the coil extends from the end faces and minimizing the length of the induction machine. The toroidal coils are configured for an arbitrary pole phase modulation wherein the coils are configured with variable numbers of phases and poles for providing maximum torque for cranking and switchable to a another phase and pole configuration for alternator operation. An adaptor ring (36) circumferentially positioned about the stator improves mechanical strength, and provides a coolant channel manifold (34) for removing heat produced in stator windings during operation.

  2. Predictive Simulations of ITER Including Neutral Beam Driven Toroidal Rotation

    SciTech Connect

    Halpern, Federico D.; Kritz, Arnold H.; Bateman, Glenn; Pankin, Alexei Y.; Budny, Robert V.; McCune, Douglas C.

    2008-06-16

    Predictive simulations of ITER [R. Aymar et al., Plasma Phys. Control. Fusion 44, 519 2002] discharges are carried out for the 15 MA high confinement mode (H-mode) scenario using PTRANSP, the predictive version of the TRANSP code. The thermal and toroidal momentum transport equations are evolved using turbulent and neoclassical transport models. A predictive model is used to compute the temperature and width of the H-mode pedestal. The ITER simulations are carried out for neutral beam injection (NBI) heated plasmas, for ion cyclotron resonant frequency (ICRF) heated plasmas, and for plasmas heated with a mix of NBI and ICRF. It is shown that neutral beam injection drives toroidal rotation that improves the confinement and fusion power production in ITER. The scaling of fusion power with respect to the input power and to the pedestal temperature is studied. It is observed that, in simulations carried out using the momentum transport diffusivity computed using the GLF23 model [R.Waltz et al., Phys. Plasmas 4, 2482 (1997)], the fusion power increases with increasing injected beam power and central rotation frequency. It is found that the ITER target fusion power of 500 MW is produced with 20 MW of NBI power when the pedesta temperature is 3.5 keV. 2008 American Institute of Physics. [DOI: 10.1063/1.2931037

  3. Rotation shear induced fluctuation decorrelation in a toroidal plasma

    SciTech Connect

    Hahm, T.S.

    1994-06-01

    The enhanced decorrelation of fluctuations by the combined effects of the E {times} B flow (V{sub E}) shear, the parallel flow (V{sub {parallel}}) shear, and the magnetic shear is studied in toroidal geometry. A two-point nonlinear analysis previously utilized in a cylindrical model shows that the reduction of the radial correlation length below its ambient turbulence value ({Delta}r{sub 0}) is characterized by the ratio between the shearing rate {omega}{sub s} and the ambient turbulence scattering rate {Delta}{omega}{sub T}. The derived shearing rate is given by {omega}{sub s}{sup 2} = ({Delta}r{sub 0}){sup 2}[1/{Delta}{phi}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(qV{sub E}/r){r_brace}{sup 2} + 1/{Delta}{eta}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(V{parallel}/qR){r_brace}{sup 2}], where {Delta}{phi} and {Delta}{eta} are the correlation angles of the ambient turbulence along the toroidal and parallel directions. This result deviates significantly from the cylindrical result for high magnetic shear or for ballooning-like fluctuations. For suppression of flute-like fluctuations, only the radial shear of qV{sub E}/r contributes, and the radial shear of V{parallel}/qR is irrelevant regardless of the plasma rotation direction.

  4. Pole-phase modulated toroidal winding for an induction machine

    SciTech Connect

    Miller, J.M.; Ostovic, V.

    1999-11-02

    A stator (10) for an induction machine for a vehicle has a cylindrical core (12) with inner and outer slots (26, 28) extending longitudinally along the inner and outer peripheries between the end faces (22, 24). Each outer slot is associated with several adjacent inner slots. A plurality of toroidal coils (14) are wound about the core and laid in the inner and outer slots. Each coil occupies a single inner slot and is laid in the associated outer slot thereby minimizing the distance the coil extends from the end faces and minimizing the length of the induction machine. The toroidal coils are configured for an arbitrary pole phase modulation wherein the coils are configured with variable numbers of phases and poles for providing maximum torque for cranking and switchable to another phase and pole configuration for alternator operation. An adaptor ring (36) circumferentially positioned about the stator improves mechanical strength, and provides a coolant channel manifold (34) for removing heat produced in stator windings during operation.

  5. Appearance of toroidal structure in dissipating laser-generated sparks

    NASA Astrophysics Data System (ADS)

    Nassif, D.; Hüwel, L.

    2000-03-01

    We have investigated the temporal and spatial evolution of laser-induced plasmas in pure nitrogen. A 1064 nm, 20 ns pulse from a neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser with pulse energies ranging from 175 to 500 mJ is tightly focused to produce a spark at various, near-atmospheric pressures. Spatially resolved Rayleigh scattered light from a time-delayed, 355 nm Nd:YAG laser pulse traversing the spark at right angles is collected with an image intensifier gated, linear diode array. At a delay time of 30 μs, the laser plasma remnant appears as a nearly spherically symmetric region with a center temperature of about 4500 K. After around 100 μs, the hot gas starts to change into a toroidal shape expanding radially at an average speed of a few meters per second. The final torus size increases with decreasing pressure and increasing laser power. This general behavior of the plasma afterglow can be reconciled with a numerical model, where in the aftermath of the spark shock wave a pair of vortices is produced which in turn moves the residual hot gas into the observed toroidal geometry.

  6. Toroidal midplane neutral beam armor and plasma limiter

    DOEpatents

    Kugel, Henry W.; Hand Jr, Samuel W.; Ksayian, Haig

    1986-02-04

    For use in a tokamak fusion reactor having a midplane magnetic coil on the inner wall of an evacuated toriodal chamber within which a neutral beam heated, fusing plasma is magnetically confined, a neutral beam armor shield and plasma limiter is provided on the inner wall of the toroidal chamber to shield the midplane coil from neutral beam shine-thru and plasma deposition. The armor shield/plasma limiter forms a semicircular enclosure around the midplane coil with the outer surface of the armor shield/plasma limiter shaped to match, as closely as practical, the inner limiting magnetic flux surface of the toroidally confined, indented, bean-shaped plasma. The armor shield/plasma limiter includes a plurality of semicircular graphite plates each having a pair of coupled upper and lower sections with each plate positioned in intimate contact with an adjacent plate on each side thereof so as to form a closed, planar structure around the entire outer periphery of the circular midplane coil. The upper and lower plate sections are adapted for coupling to heat sensing thermocouples and to a circulating water conduit system for cooling the armor shield/plasma limiter.The inner center portion of each graphite plate is adapted to receive and enclose a section of a circular diagnostic magnetic flux loop so as to minimize the power from the plasma confinement chamber incident upon the flux loop.

  7. Toroidal midplane neutral beam armor and plasma limiter

    DOEpatents

    Kugel, Henry W.; Hand, Jr, Samuel W.; Ksayian, Haig

    1986-01-01

    For use in a tokamak fusion reactor having a midplane magnetic coil on the inner wall of an evacuated toriodal chamber within which a neutral beam heated, fusing plasma is magnetically confined, a neutral beam armor shield and plasma limiter is provided on the inner wall of the toroidal chamber to shield the midplane coil from neutral beam shine-thru and plasma deposition. The armor shield/plasma limiter forms a semicircular enclosure around the midplane coil with the outer surface of the armor shield/plasma limiter shaped to match, as closely as practical, the inner limiting magnetic flux surface of the toroidally confined, indented, bean-shaped plasma. The armor shield/plasma limiter includes a plurality of semicircular graphite plates each having a pair of coupled upper and lower sections with each plate positioned in intimate contact with an adjacent plate on each side thereof so as to form a closed, planar structure around the entire outer periphery of the circular midplane coil. The upper and lower plate sections are adapted for coupling to heat sensing thermocouples and to a circulating water conduit system for cooling the armor shield/plasma limiter.The inner center portion of each graphite plate is adapted to receive and enclose a section of a circular diagnostic magnetic flux loop so as to minimize the power from the plasma confinement chamber incident upon the flux loop.

  8. General Linear Rf-Current Drive Calculation in Toroidal Plasma

    NASA Astrophysics Data System (ADS)

    Smirnov, A. P.; Harvey, R. W.; Prater, R.

    2009-04-01

    A new general linear calculation of RF current drive has been implemented in the GENRAY all-frequencies RF ray tracing code. This is referred to as the ADJ-QL package, and is based on the Karney, et al. [1] relativistic Green function calculator, ADJ, generalized to non-circular plasmas in toroidal geometry, and coupled with full, bounce-averaged momentum-space RF quasilinear flux [2] expressions calculated at each point along the RF ray trajectories. This approach includes momentum conservation, polarization effects and the influence of trapped electrons. It is assumed that the electron distribution function remains close to a relativistic Maxwellian function. Within the bounds of these assumptions, small banana width, toroidal geometry and low collisionality, the calculation is applicable for all-frequencies RF electron current drive including electron cyclotron, lower hybrid, fast waves and electron Bernstein waves. GENRAY ADJ-QL calculations of the relativistic momentum-conserving current drive have been applied in several cases: benchmarking of electron cyclotron current drive in ITER against other code results; and electron Bernstein and high harmonic fast wave current drive in NSTX. The impacts of momentum conservation on the current drive are also shown for these cases.

  9. On the Toroidal Plasma Rotations Induced by Lower Hybrid Waves

    SciTech Connect

    Guan, Xiaoyin; Qin, Hong; Liu, Jian; Fisch, Nathaniel J.

    2012-11-14

    A theoretical model is developed to explain the plasma rotations induced by lower hybrid waves in Alcator C-Mod. In this model, torodial rotations are driven by the Lorentz force on the bulk electron flow across flux surfaces, which is a response of the plasma to the resonant-electron flow across flux surfaces induced by the lower hybrid waves. The flow across flux surfaces of the resonant electrons and the bulk electrons are coupled through the radial electric fi eld initiated by the resonant electrons, and the friction between ions and electrons transfers the toroidal momentum to ions from electrons. An improved quasilinear theory with gyrophase dependent distribution function is developed to calculate the perpendicular resonant-electron flow. Toroidal rotations are determined using a set of fluid equations for bulk electrons and ions, which are solved numerically by a fi nite- difference method. Numerical results agree well with the experimental observations in terms of flow pro file and amplitude. The model explains the strong correlation between torodial flow and internal inductance observed experimentally, and predicts both counter-current and co-current flows, depending on the perpendicular wave vectors of the lower hybrid waves. __________________________________________________

  10. From toroidal to rod-like condensates of semiflexible polymers.

    PubMed

    Hoang, Trinh Xuan; Giacometti, Achille; Podgornik, Rudolf; Nguyen, Nhung T T; Banavar, Jayanth R; Maritan, Amos

    2014-02-14

    The competition between toroidal and rod-like conformations as possible ground states for DNA condensation is studied as a function of the stiffness, the length of the DNA, and the form of the long-range interactions between neighboring molecules, using analytical theory supported by Monte Carlo simulations. Both conformations considered are characterized by a local nematic order with hexagonal packing symmetry of neighboring DNA molecules, but differ in global configuration of the chain and the distribution of its curvature as it wraps around to form a condensate. The long-range interactions driving the DNA condensation are assumed to be of the form pertaining to the attractive depletion potential as well as the attractive counterion induced soft potential. In the stiffness-length plane we find a transition between rod-like to toroid condensate for increasing stiffness at a fixed chain length L. Strikingly, the transition line is found to have a L(1/3) dependence irrespective of the details of the long-range interactions between neighboring molecules. When realistic DNA parameters are used, our description reproduces rather well some of the experimental features observed in DNA condensates. PMID:24527935

  11. Design study of toroidal traction CVT for electric vehicles

    NASA Technical Reports Server (NTRS)

    Raynard, A. E.; Kraus, J.; Bell, D. D.

    1980-01-01

    The development, evaluation, and optimization of a preliminary design concept for a continuously variable transmission (CVT) to couple the high-speed output shaft of an energy storage flywheel to the drive train of an electric vehicle is discussed. An existing computer simulation program was modified and used to compare the performance of five CVT design configurations. Based on this analysis, a dual-cavity full-toroidal drive with regenerative gearing is selected for the CVT design configuration. Three areas are identified that will require some technological development: the ratio control system, the traction fluid properities, and evaluation of the traction contact performance. Finally, the suitability of the selected CVT design concept for alternate electric and hybrid vehicle applications and alternate vehicle sizes and maximum output torques is determined. In all cases the toroidal traction drive design concept is applicable to the vehicle system. The regenerative gearing could be eliminated in the electric powered vehicle because of the reduced ratio range requirements. In other cases the CVT with regenerative gearing would meet the design requirements after appropriate adjustments in size and reduction gearing ratio.

  12. Spectroscopy of High Velocity Compact Toroids on CTIX

    NASA Astrophysics Data System (ADS)

    Jungwirth, Nick; Horton, Robert; Klauser, Ruth; Hwang, David

    2010-11-01

    High density toroidal plasmas can reach speeds exceeding 200 km/s using coaxial accelerators such as CTIX at UC Davis. Applications of these compact toroids (CTs) include the fueling of next generation tokamaks and stellarators. An important CT diagnostic is to monitor atomic line radiation from CT ions. In this investigation we develop a reliable method of measuring a broad range (40 nm) of the CT spectrum from multiple positions. Our system employs fiber-optic cables to transmit the signal to a spectrometer operating in the 300-1300 nm range. A gated, intensified, CCD camera surveys the CT emission spectrum at a fixed time over a range of wavelengths. Additionally, a photomultiplier is used to investigate the time dependence of particular wavelengths of interest (monochrometer mode). Such measurements enable the study of CT temperature, density, impurity content, and CT velocity. The fiber-optic system will first be used to survey the emission spectrum of CTIX in typical operation, and to identify candidate lines for monochrometer operation.

  13. Theoretical Analysis of the Electron Spiral Toroid Concept

    NASA Technical Reports Server (NTRS)

    Cambier, Jean-Luc; Micheletti, David A.; Bushnell, Dennis M. (Technical Monitor)

    2000-01-01

    This report describes the analysis of the Electron Spiral Toroid (EST) concept being promoted by Electron Power Systems Inc. (EPS). The EST is described as a toroidal plasma structure composed Of ion and electron shells. It is claimed that the EST requires little or no external confinement, despite the extraordinarily large energy densities resulting from the self-generating magnetic fields. The present analysis is based upon documentation made available by EPS, a previous description of the model by the Massachusetts Institute of Technology (MIT), and direct discussions with EPS and MIT. It is found that claims of absolute stability and large energy storage capacities of the EST concept have not been substantiated. Notably, it can be demonstrated that the ion fluid is fundamentally unstable. Although various scenarios for ion confinement were subsequently suggested by EPS and MIT, none were found to be plausible. Although the experimental data does not prove the existence of EST configurations, there is undeniable experimental evidence that some type of plasma structures whose characteristics remain to be determined are observed. However, more realistic theoretical models must first be developed to explain their existence and properties before applications of interest to NASA can he assessed and developed.

  14. Island Divertor Plate Modeling for the Compact Toroidal Hybrid Experiment

    NASA Astrophysics Data System (ADS)

    Hartwell, G. J.; Massidda, S. D.; Ennis, D. A.; Knowlton, S. F.; Maurer, D. A.; Bader, A.

    2015-11-01

    Edge magnetic island divertors can be used as a method of plasma particle and heat exhaust in long pulse stellarator experiments. Detailed power loading on these structures and its relationship to the long connection length scrape off layer physics is a new Compact Toroidal Hybrid (CTH) research thrust. CTH is a five field period, l = 2 torsatron with R0 = 0 . 75 m, ap ~ 0 . 2 m, and | B | <= 0 . 7 T. For these studies CTH is configured as a pure stellarator using a 28 GHz, 200 kW gyrotron operating at 2nd harmonic for ECRH. We report the results of EMC3-EIRENE modeling of divertor plates near magnetic island structures. The edge rotational transform is varied by adjusting the ratio of currents in the helical and toroidal field coils. A poloidal field coil adjusts the shear of the rotational transform profile, and width of the magnetic island, while the phase of the island is rotated with a set of five error coils producing an n = 1 perturbation. For the studies conducted, a magnetic configuration with a large n = 1 , m = 3 magnetic island at the edge is generated. Results from multiple potential divertor plate locations will be presented and discussed. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

  15. Interplay between toroidal rotation and flow shear in turbulence stabilisation

    NASA Astrophysics Data System (ADS)

    Camenen, Y.; Casson, F. J.; Manas, P.; Peeters, A. G.

    2016-02-01

    The interplay between toroidal rotation u, parallel flow shear u', and perpendicular flow shear γE in the stabilisation of tokamak turbulence is investigated in non-linear flux-tube gyrokinetic simulations. The simulations are performed for a reference L-mode DIII-D plasma (the so-called shortfall case) at r /a =0.8 , varying the flow parameters around their nominal values. Depending on the respective signs of u, u', and γE, turbulence is found to be enhanced, reduced, or unchanged. When the coupling is favorable, the overall effect on the non-linear heat fluxes can be very large, even at moderate flow values. The ion heat flux is, for instance, decreased by a factor of 3 when the direction of the parallel flow shear is reversed with respect to its nominal value. Even more surprising, keeping u' and γE at their nominal values, the ion heat flux decreases by more than 50% when the toroidal flow is reversed. The relevance of this mechanism in the experiments which depends on the ability to decouple u, u', and γE is discussed. The interplay between u and u' observed in the non-linear simulations qualitatively follows the linear stability results and is interpreted in the frame of a simple fluid model.

  16. Convection in three dimensions with surface plates - Generation of toroidal flow

    NASA Technical Reports Server (NTRS)

    Gable, Carl W.; O'Connell, Richard J.; Travis, Bryan J.

    1991-01-01

    This work presents numerical calculations of mantle convection that incorporate some of the basic observational constraints imposed by plate tectonics. The model is three-dimensional and includes surface plates; it allows plate velocity to change dynamically according to the forces which result from convection. It is shown that plates are an effective means of introducing a toroidal component into the flow field. After initial transients the plate motion is nearly parallel to transform faults and in the direction that tends to minimize the toroidal flow field. The toroidal field decays with depth from its value at the surface; the poloidal field is relatively constant throughout the layer but falls off slightly at the top and bottom boundaries. Layered viscosity increasing with depth causes the toroidal field to decay more rapidly, effectively confining it to the upper, low-viscosity layer. The effect of viscosity layering on the poloidal field is relatively small, which is attributed to its generation by temperature variations distributed throughout the system. The generation of toroidal flow by surface plates would seem to account for the observed nearly equal energy of toroidal and poloidal fields of plate motions on the earth. A low-viscosity region in the upper mantle will cause the toroidal flow to decay significantly before reaching the lower mantle. The resulting concentration of toroidal flow in the upper mantle may result in more thorough mixing there and account for some of the geochemical and isotopic differences proposed to exist between the upper and lower mantles.

  17. Report for collisional and chaotic transport of energetic particles in toroidal plasma

    SciTech Connect

    Cary, J.R.; Shasharina, S.G.

    1995-04-01

    The authors have made progress in two general areas of confinement plasma physics. (1) We studies a new loss mechanism of the toroidally trapped particles related to the up-down asymmetry of ripple in a tokamak. (2) We estimated the bootstrap current of the particles making transitions between the toroidally and locally states in non-axisymmetric tori, stellarators and tokamaks.

  18. The psoriasis-associated D10N variant of the adaptor Act1 with impaired regulation by the molecular chaperone hsp90.

    PubMed

    Wang, Chenhui; Wu, Ling; Bulek, Katarzyna; Martin, Bradley N; Zepp, Jarod A; Kang, Zizhen; Liu, Caini; Herjan, Tomasz; Misra, Saurav; Carman, Julie A; Gao, Ji; Dongre, Ashok; Han, Shujie; Bunting, Kevin D; Ko, Jennifer S; Xiao, Hui; Kuchroo, Vijay K; Ouyang, Wenjun; Li, Xiaoxia

    2013-01-01

    Act1 is an essential adaptor in interleukin 17 (IL-17)-mediated signaling and is recruited to the receptor for IL-17 after stimulation with IL-17. Here we found that Act1 was a 'client' protein of the molecular chaperone hsp90. The D10N variant of Act1 (Act1(D10N)) that is linked to susceptibility to psoriasis was defective in its interaction with hsp90, which resulted in a global loss of Act1 function. Act1-deficient mice modeled the mechanistic link between loss of Act1 function and susceptibility to psoriasis. Although Act1 was necessary for IL-17-mediated inflammation, Act1-deficient mice had a hyperactive response of the T(H)17 subset of helper T cells and developed spontaneous IL-22-dependent skin inflammation. In the absence of IL-17 signaling, IL-22 was the main contributor to skin inflammation, which provides a molecular mechanism for the association of Act1(D10N) with psoriasis susceptibility. PMID:23202271

  19. Effects of electron-cyclotron-resonance-heating-induced internal kink mode on the toroidal rotation in the KSTAR Tokamak.

    PubMed

    Seol, J; Lee, S G; Park, B H; Lee, H H; Terzolo, L; Shaing, K C; You, K I; Yun, G S; Kim, C C; Lee, K D; Ko, W H; Kwak, J G; Kim, W C; Oh, Y K; Kim, J Y; Kim, S S; Ida, K

    2012-11-01

    It is observed that the magnitude of the toroidal rotation speed is reduced by the central electron cyclotron resonance heating (ECRH) regardless of the direction of the toroidal rotation. The magnetohydrodynamics activities generally appear with the rotation change due to ECRH. It is shown that the internal kink mode is induced by the central ECRH and breaks the toroidal symmetry. When the magnetohydrodynamics activities are present, the toroidal plasma viscosity is not negligible. The observed effects of ECRH on the toroidal plasma rotation are explained by the neoclassical toroidal viscosity in this Letter. It is found that the neoclassical toroidal viscosity torque caused by the internal kink mode damps the toroidal rotation. PMID:23215391

  20. Turbulence in Toroidally Confined Plasma: Ion - - Gradient-Driven Turbulence; Dynamics of Magnetic Relaxation in Current-Carrying Plasma

    NASA Astrophysics Data System (ADS)

    Lee, Gyung Su.

    This thesis is devoted to two studies of low-frequency turbulence in toroidally confined plasma. Low-frequency turbulence is believed to play an important role in anomalous transport in toroidal confinement devices. The first study pertains the the development of an analytic theory of ion-temperature-gradient-driven turbulence in tokamaks. Energy-conserving, renormalized spectrum equations are derived and solved in order to obtain the spectra of stationary ion-temperature-gradient-driven turbulence. Corrections to mixing-length estimates are calculated explicitly. The resulting anomalous ion thermal diffusivity is derived and is found to be consistent with experimentally-deduced ion thermal diffusivities. The associated electron thermal diffusivity, particle and heat-pinch velocities are also calculated. The effects of impurity gradients on saturated ion-temperature-gradient-driven turbulence are discussed and a related explanation of density profile steepening during Z-mode operation is proposed. The second study is devoted to the role of multiple helicity nonlinear interactions of tearing modes and dynamics of magnetic relaxation in a high-temperature current-carrying plasma. To extend the resistive MHD theory of magnetic fluctuations and dynamo activity observed in the reversed field pinch, the fluid equations for high-temperature regime are derived and basic nonlinear interaction mechanism and the effects of diamagnetic corrections to the MHD turbulence theory are studied for the case of fully developed, densely packed turbulence. Modifications to the MHD dynamo theory and anomalous thermal transport and confinement scaling predictions are examined.

  1. Observation of the self-generated toroidal magnetic field in rotamak

    SciTech Connect

    Petrov, Yuri; Zhong Fangchuan; Huang Tiansen

    2005-08-15

    An experimental study of the self-generated toroidal magnetic field in rotamak field-reversed configuration plasmas is performed in the case of high input power (200 kW), long-duration (40 ms) discharges. In one round of experiments, the polarity of the toroidal field in the poloidal cross section is different not only from one hemisphere to another but also in radial direction. In another round of experiments, the toroidal field is seen to reverse its sign in the course of a shot. The data for the field are fitted with the vector spherical harmonic functions. The poloidally swirling currents associated with the self-generated toroidal field are shown to contribute to the formation of the two-peak structure of the toroidal plasma current.

  2. Prediction of plasma rotation and neoclassical toroidal viscosity in KSTAR discharges based on plasma fluid formulation

    NASA Astrophysics Data System (ADS)

    Bae, Cheonho; Stacey, Weston

    2015-11-01

    Braginskii's flow rate of strain tensor formalism, as extended first to low collisional plasmas in axisymmetric circular toroidal flux surface geometry, then to elongated axisymmetric flux surface geometry, has recently been extended to 3-D non-axisymmetric toroidal flux surface geometry. In toroidally non-axisymmetric plasmas, the leading order neoclassical parallel viscosity terms in the flow rate of strain tensor do not vanish to cause flux surface averaged toroidal angular momentum damping and eventually slow down the plasma rotation. The formalism of Ref. 5 provides a means to systematically evaluate the ``neoclassical toroidal viscosity (NTV)'' in curvilinear plasma geometry based on the plasma fluid equations. As the first step of its application, a practical formalism for circular plasmas, given in the appendix of Ref. 5, will be applied to KSTAR discharges to predict the rotation and NTV, which can also be compared with actual rotation measurements to numerically validate the NTV damping effects.

  3. Transport of Parallel Momentum Induced by Current-Symmetry Breaking in Toroidal Plasmas

    SciTech Connect

    Camenen, Y.; Peeters, A. G.; Casson, F. J.; Hornsby, W. A.; Snodin, A. P.; Angioni, C.; Strintzi, D.

    2009-03-27

    The symmetry of a physical system strongly impacts on its properties. In toroidal plasmas, the symmetry along a magnetic field line usually constrains the radial flux of parallel momentum to zero in the absence of background flows. By breaking the up-down symmetry of the toroidal currents, this constraint can be relaxed. The parallel asymmetry in the magnetic configuration then leads to an incomplete cancellation of the turbulent momentum flux across a flux surface. The magnitude of the subsequent toroidal rotation increases with the up-down asymmetry and its sign depends on the direction of the toroidal magnetic field and plasma current. Such a mechanism offers new insights in the interpretation and control of the intrinsic toroidal rotation in present day experiments.

  4. Matter in the form of toroidal electromagnetic vortices

    NASA Astrophysics Data System (ADS)

    Hagen, Wilhelm F.

    2015-09-01

    The creation of charged elementary particles from neutral photons is explained as a conversion process of electromagnetic (EM) energy from linear to circular motion at the speed of light into two localized, toroidal shaped vortices of trapped EM energy that resist change of motion, perceptible as particles with inertia and hence mass. The photon can be represented as a superposition of left and right circular polarized transverse electric fields of opposite polarity originating from a common zero potential axis, the optical axis of the photon. If these components are separated by interaction with a strong field (nucleon) they would curl up into two electromagnetic vortices (EMV) due to longitudinal magnetic field components forming toroids. These vortices are perceptible as opposite charged elementary particles e+/- . These spinning toroids generate extended oscillating fields that interact with stationary field oscillations. The velocity-dependent frequency differences cause beat signals equivalent to matter waves, leading to interference. The extended fields entangled with every particle explain wave particle duality issues. Spin and magnetic moment are the natural outcome of these gyrating particles. As the energy and hence mass of the electron increases with acceleration so does its size shrink proportional to its reduced wavelength. The artificial weak and strong nuclear forces can be easily explained as different manifestations of the intermediate EM forces. The unstable neutron consists of a proton surrounded by a contracted and captured electron. The associated radial EM forces represent the weak nuclear force. The deuteron consists of two axially separated protons held together by a centrally captured electron. The axial EM forces represent the strong nuclear force, providing stability for "neutrons" only within nucleons. The same principles were applied to determine the geometries of force-balanced nuclei. The alpha-particle emerges as a very compact

  5. Instability of Toroidal Magnetic Field in Jets and Plerions

    NASA Astrophysics Data System (ADS)

    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

  6. Proceedings of the third symposium on the physics and technology of compact toroids in the magnetic fusion energy program

    SciTech Connect

    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 (FRC's that contain purely poloidal field).

  7. Neoclassical transport in toroidal plasmas with nonaxisymmetric flux surfaces

    NASA Astrophysics Data System (ADS)

    Belli, E. A.; Candy, J.

    2015-05-01

    The capability to treat nonaxisymmetric flux surface geometry has been added to the drift-kinetic code NEO (Belli and Candy 2008 Plasma Phys. Control. Fusion 50 095010). Geometric quantities (i.e. metric elements) are supplied by a recently-developed local 3D equilibrium solver, allowing neoclassical transport coefficients to be systematically computed while varying the 3D plasma shape in a simple and intuitive manner. Code verification is accomplished via detailed comparison with 3D Pfirsch-Schlüter theory. A discussion of the various collisionality regimes associated with 3D transport is given, with an emphasis on non-ambipolar particle flux, neoclassical toroidal viscosity, energy flux and bootstrap current. Finally, we compute the transport in the presence of ripple-type perturbations in a DIII-D-like H-mode edge plasma.

  8. Geodesic acoustic mode in toroidally rotating anisotropic tokamaks

    SciTech Connect

    Ren, Haijun

    2015-07-15

    Effects of anisotropy on the geodesic acoustic mode (GAM) are analyzed by using gyro-kinetic equations applicable to low-frequency microinstabilities in a toroidally rotating tokamak plasma. Dispersion relation in the presence of arbitrary Mach number M, anisotropy strength σ, and the temperature ration τ is analytically derived. It is shown that when σ is less than 3 + 2τ, the increased electron temperature with fixed ion parallel temperature increases the normalized GAM frequency. When σ is larger than 3 + 2τ, the increasing of electron temperature decreases the GAM frequency. The anisotropy σ always tends to enlarge the GAM frequency. The Landau damping rate is dramatically decreased by the increasing τ or σ.

  9. Transport scaling in interchange-driven toroidal plasmas

    SciTech Connect

    Ricci, Paolo; Rogers, B. N.

    2009-06-15

    Two-dimensional fluid simulations of a simple magnetized torus are presented, in which the vertical and toroidal components of the magnetic field create helicoidal field lines that terminate on the upper and lower walls of the plasma chamber. The simulations self-consistently evolve the full radial profiles of the electric potential, density, and electron temperature in the presence of three competing effects: the cross-field turbulent transport driven by the interchange instability, parallel losses to the upper and lower walls, and the input of particles and heat by external plasma sources. Considering parameter regimes in which equilibrium ExB shear flow effects are weak, we study the dependence of the plasma profiles--in particular the pressure profile scale length--on the parameters of the system. Analytical scalings are obtained that show remarkable agreement with the simulations.

  10. Heterotic free fermionic and symmetric toroidal orbifold models

    NASA Astrophysics Data System (ADS)

    Athanasopoulos, P.; Faraggi, A. E.; Nibbelink, S. Groot; Mehta, V. M.

    2016-04-01

    Free fermionic models and symmetric heterotic toroidal orbifolds both constitute exact backgrounds that can be used effectively for phenomenological explorations within string theory. Even though it is widely believed that for Z_2× Z_2 orbifolds the two descriptions should be equivalent, a detailed dictionary between both formulations is still lacking. This paper aims to fill this gap: we give a detailed account of how the input data of both descriptions can be related to each other. In particular, we show that the generalized GSO phases of the free fermionic model correspond to generalized torsion phases used in orbifold model building. We illustrate our translation methods by providing free fermionic realizations for all Z_2× Z_2 orbifold geometries in six dimensions.

  11. Existence of core localized toroidicity-induced Alfven eigenmode

    SciTech Connect

    Fu, G.Y. )

    1995-04-01

    The core-localized toroidicity-induced Alfven eigenmode (TAE) is shown to exist at finite plasma pressure due to finite aspect ratio effects in tokamak plasma. The new critical beta for the existence of the TAE mode is given by [alpha][approx]3[epsilon]+2[ital s][sup 2], where [epsilon]=[ital r]/[ital R] is the inverse aspect ratio, [ital s] is the magnetic shear and [alpha]=[minus][ital Rq][sup 2][ital d][beta]/[ital dr] is the normalized pressure gradient. In contrast, previous critical [alpha] is given by [alpha][approx][ital s][sup 2]. In the limit of [ital s][much lt][radical][ital r]/[ital R], the new critical [alpha] is greatly enhanced by the finite aspect ratio effects.

  12. Equilibrium and Stability of Partial Toroidal Plasma Discharges

    SciTech Connect

    Oz, E.; Myers, C. E.; Yamada, M.; Ji, H.; Kulsrud, R.; Xie, J.

    2011-01-04

    The equilibrium and stability of partial toroidal flux ropes are studied in detail in the laboratory, motivated by ubiquitous loop structures on the solar surface. The flux ropes studied here are magnetized arc discharges formed in the Magnetic Reconnection Experiment (MRX). It is found that these loops robustly maintain their equilibrium on time scales much longer than the Alfven time over a wide range of plasma current, guide eld strength, and angle between electrodes, even in the absence of a strapping fi eld. Additionally, the external kink stability of these flux ropes is found to be governed by the Kruskal-Shafranov limit for a flux rope with line-tied boundary conditions at both ends (q > 1).

  13. Process analyses of ITER Toroidal Field Structure cooling scheme

    NASA Astrophysics Data System (ADS)

    Maekawa, R.; Takami, S.; Iwamoto, A.; Chang, H. S.; Forgeas, A.; Chalifour, M.; Serio, L.

    2014-09-01

    Process studies for Toroidal Field Structure (TF ST) system with a dedicated Auxiliary Cold Box (ACB-ST) have been conducted under 15 MA baseline, including plasma disruptions. ACB-ST consists of two heat exchangers immersed in the Liquid Helium (LHe) subcooler, which are placed at the inlet/outlet of a Supercritical Helium (SHe) cold circulator (centrifugal pump). Robustness of ACB-ST is a key to achieve the stability of TF coil operation since it provides the thermal barrier at the interface of the TF Winding Pack (WP) with ST. The paper discusses the control logic for the nominal plasma operating scenario and for Mitigation to regulate the dynamic heat loads on ST. In addition, the operation field of a cold circulator is described in the case of plasma disruptions. The required performance of heat exchangers in the ACB-ST is assessed based on the expected operating conditions.

  14. Design and evaluation of a toroidal wheel for planetary rovers

    NASA Technical Reports Server (NTRS)

    Koskol, J.; Yerazunis, S. W.

    1977-01-01

    The inverted toroidal wheel concept was perceived, mathematically quantified, and experimentally verified. The wheel design has a number of important characteristics, namely; (1) the low footprint pressures required for Mars exploration (0.5 to 1.0 psi); (2) high vehicle weight to wheel weight ratios capable of exceeding 10:1; (3) extremely long cyclic endurances tending towards infinite life; and (4) simplicity of design. The concept, in combination with appropriate materials such as titanium or composites, provides a planetary roving vehicle with a very high degree of exploratory mobility, a substantial savings in weight and a high assurity of mission success. Design equations and computation procedures necessary to formulate an inverted wheel are described in detail.

  15. Generation and Stability of Toroidal Droplets in a Viscous Liquid

    NASA Astrophysics Data System (ADS)

    Pairam, E.; Fernández-Nieves, A.

    2009-06-01

    We use a simple method to generate toroidal droplets and study how they transform into spherical droplets. The method relies on the viscous forces exerted by a rotating continuous phase over a liquid which is extruded from an injection needle; the resultant jet is forced to close into a torus due to the imposed rotation. Once formed, the torus transforms into single or multiple spheres. Interestingly, we find there are two routes for this process depending on the aspect ratio of the torus. For thin tori, classical hydrodynamic instabilities induce its breakup into a precise number of droplets. By contrast, for sufficiently fat tori, unstable modes are unable to grow, and the torus evolves through a different route; it shrinks towards its center to coalesce onto itself, to finally form a single spherical droplet.

  16. Existence of core localized toroidicity-induced Alfven eigenmode

    SciTech Connect

    Fu, G.Y.

    1995-02-01

    The core-localized toroidicity-induced Alfven eigenmode (TAE) is shown to exist at finite plasma pressure due to finite aspect ratio effects in tokamak plasma. The new critical beta for the existence of the TAE mode is given by {alpha}{approx} 3{epsilon} + 2s{sup 2}, where {epsilon} = r/R is the inverse aspect ratio, s is the magnetic shear and {alpha} = -Rq{sup 2}d{beta}/dr is the normalized pressure gradient. In contrast, previous critical {alpha} is given by {alpha} {approx} s{sup 2}. In the limit of s << {radical}r/R, the new critical {alpha} is greatly enhanced by the finite aspect ratio effects.

  17. Recent results of studies of acceleration of compact toroids

    NASA Astrophysics Data System (ADS)

    Hammer, J. H.; Hartmen, C. W.; Eddleman, J.

    1984-03-01

    The observed gross stability and self-contained structure of compact toroids (CT's) give rise to the possibility, unique among magnetically confined plasmas, of translating CT's from their point of origin over distances many times their own length. This feature has led us to consider magnetic acceleration of CT's to directed kinetic energies much greater than their stored magnetic and thermal energies. A CT accelerator falls in the very broad gap between traditional particle accelerators at one extreme, which are limited in the number of particles per bunch by electrostatic repulsive forces, and mass accelerators such as rail guns at the other extreme, which accelerate many particles but are forced by the stress limitations of solids to far smaller accelerations. A typical CT has about a Coulomb of particles, weighs 10 micrograms and can be accelerated by magnetic forces of several tons, leading to an acceleration on the order of 10(11) gravities.

  18. Analysis of Recurrent Patterns in Toroidal Magnetic Fields

    SciTech Connect

    Tricoche, Xavier; Kruger, Scott E; Breslau, Joshua

    2010-01-01

    In the development of magnetic confinement fusion which will potentially be a future source for low cost power, physicists must be able to analyze the magnetic field that confines the burning plasma. While the magnetic field can be described as a vector field, traditional techniques for analyzing the field's topology cannot be used because of its Hamiltonian nature. In this paper we describe a technique developed as a collaboration between physicists and computer scientists that determines the topology of a toroidal magnetic field using fieldlines with near minimal lengths. More specifically, we analyze the Poincare map of the sampled fieldlines in a Poincare section including identifying critical points and other topological features of interest to physicists. The technique has been deployed into an interactive parallel visualization tool which physicists are using to gain new insight into simulations of magnetically confined burning plasmas.

  19. Turbulent equipartition pinch of toroidal momentum in spherical torus

    NASA Astrophysics Data System (ADS)

    Hahm, T. S.; Lee, J.; Wang, W. X.; Diamond, P. H.; Choi, G. J.; Na, D. H.; Na, Y. S.; Chung, K. J.; Hwang, Y. S.

    2014-12-01

    We present a new analytic expression for turbulent equipartition (TEP) pinch of toroidal angular momentum originating from magnetic field inhomogeneity of spherical torus (ST) plasmas. Starting from a conservative modern nonlinear gyrokinetic equation (Hahm et al 1988 Phys. Fluids 31 2670), we derive an expression for pinch to momentum diffusivity ratio without using a usual tokamak approximation of B ∝ 1/R which has been previously employed for TEP momentum pinch derivation in tokamaks (Hahm et al 2007 Phys. Plasmas 14 072302). Our new formula is evaluated for model equilibria of National Spherical Torus eXperiment (NSTX) (Ono et al 2001 Nucl. Fusion 41 1435) and Versatile Experiment Spherical Torus (VEST) (Chung et al 2013 Plasma Sci. Technol. 15 244) plasmas. Our result predicts stronger inward pinch for both cases, as compared to the prediction based on the tokamak formula.

  20. EMPACT: Electrons Muons Partons with Air Core Toroids

    SciTech Connect

    Marx, M.D. )

    1990-05-25

    The EMPACT experiment utilizes a broad approach to maximize its discovery potential for new phenomena accessible at the SSC. The high resolution detector has a balances emphasis on, and large acceptance for, electrons, muons, jets, and noninteracting particles, and is capable of utilizing the ultimate luminosity of the SSC. The detector emphasizes excellent calorimetry augmented by TRD tracking, and employs an innovative system of superconducting air core toroids for muon measurements. Significant engineering effort has established the feasibility of a baseline detector concept and has addressed the related issues of support facilities, assembly, and detector integration. The design has been tested against the challenges of predicted phenomena, with the expectation that this will optimize the capacity for observing the unexpected. EMPACT's international collaboration has unprecedented support from major aerospace industries who are providing tools and expertise for project design and integration, which will assure that a detector optimized for performance and cost will be available for the first collisions at the new laboratory.

  1. Fluid simulations of toroidal ion temperature gradient turbulence

    SciTech Connect

    Sandberg, I.; Isliker, H.; Pavlenko, V.P.; Hizanidis, K.; Vlahos, L.

    2006-02-15

    The evolution of the toroidal ion temperature gradient mode instability is numerically studied by using the equations based on the standard reactive fluid model. The long-term dynamics of the instability are investigated using random-phase, small-amplitude fluctuations for initial conditions. The main events during the evolution of the instability that lead to the formation of large-scale coherent structures are described and the role of the dominant nonlinearities is clarified. The polarization drift nonlinearity leads to the inverse energy cascade while the convective ion heat nonlinearity is responsible for the saturation of the instability. Finally, the sensitivity of the saturated state to the initial plasma conditions is examined.

  2. Vortex excitation in a stirred toroidal Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Yakimenko, A. I.; Isaieva, K. O.; Vilchinskii, S. I.; Ostrovskaya, E. A.

    2015-02-01

    Motivated by a recent experiment [K. C. Wright et al., Phys. Rev. A 88, 063633 (2013), 10.1103/PhysRevA.88.063633], we investigate the microscopic mechanism for excitation of vortices and formation of a persistent current in an annular BEC stirred by a narrow blue-detuned optical beam. In the framework of a two-dimensional mean-field model, we study the dissipative dynamics of the condensate with parameters that reflect realistic experimental conditions. Vortex-antivortex pairs appear near the center of the stirrer in the bulk of the condensate for slow motion of the stirring beam. When the barrier angular velocity is above some critical value, an outer edge surface mode develops and breaks into the vortices entering the condensate annulus. We determine the conditions for creation of vortex excitations in the stirred toroidal condensate and compare our results with experimental observations.

  3. Evolution of toroidal Alfven eigenmode instability in TFTR

    SciTech Connect

    Wong, K.L.; Majeski, R.; Petrov, M.

    1996-07-01

    The nonlinear behavior of the Toroidal Alfven Eigenmode (TAE) driven unstable by energetic ions in TFTR is studied. The evolution of instabilities can take on several scenarios: a single mode or several modes can be driven unstable at the same time, the spectrum can be steady or pulsating and there can be negligible or anomalous loss associated with the instability. This paper presents a comparison between experimental results and recently developed nonlinear theory. The authors find many features observed in experiment are compatible with the consequences of the nonlinear theory. Examples include the structure of the saturated pulse that emerges from the onset of instability of a single mode and the decrease but persistence of TAE signals when the applied rf power is reduced or shut off.

  4. Advances in the Fabrication of Toroidal Field Coil Prototypes*

    NASA Astrophysics Data System (ADS)

    Pizzuto, A.; Cucchiaro, A.; Frosi, R.; Ramogida, G.; Boert, F.; Wobker, H. G.; Bianchi, A.; Parodi, B.; Coppi, B.

    2006-10-01

    The Bitter-type Toroidal Field Coils (TFC) adopted for Ignitor consist of plates that are cooled down to 30 K by Helium gas. Copper OFHC has been selected for these plates, allowing for an Electron Beam (EB) welding solution of the cooling channels. Kabel Metal set up the welding parameters and qualified the process to achieve full joint penetration with acceptable metallurgical structure. The qualification covers both the welding of the cooling channels and the inlet/outlet tube made on two full size samples. A metallographic examination and vacuum and pressure tests have been preformed to validate the basic suitability of the EB welding process. *Sponsored in part by ENEA of Italy and by the U.S. DOE.

  5. Compact toroidal ion-trap design and optimization

    SciTech Connect

    Madsen, M. J.; Gorman, C. H.

    2010-10-15

    We present the design of a type of compact toroidal, or 'halo', ion trap. Such traps may be useful for mass spectrometry, studying small Coulomb cluster rings, quantum-information applications, or other quantum simulations where a ring topology is of interest. We present results from a Monte Carlo optimization of the trap design parameters using finite-element analysis simulations that minimize higher-order anharmonic terms in the trapping pseudopotential, while maintaining complete control over ion placement at the pseudopotential node in three dimensions using static bias fields. These simulations are based on a practical electrode design using readily available parts, yet can be easily scaled to any size trap with similar electrode spacings. We also derive the conditions for a crystal structure transition for two ions in the compact halo trap, the first nontrivial transition for Coulomb crystals in this geometry.

  6. Modeling the rapid de-swelling of toroidal hydrogels

    NASA Astrophysics Data System (ADS)

    Nikolov, Svetoslav; Chang, Ya-Wen; Alexeev, Alexander; Fernandez de Las Nieves, Alberto

    2015-03-01

    The utilization of synthetic hydrogel networks as 3-D cell culture platforms has allowed researchers to more effectively study how epigenetic factors affect cell growth and physiology. As a whole, this has emphasized the biomechanical role of scaffold structures and led to a number of advances in tissue engineering. Our current research focuses on modeling temperature activated shape transformations of toroidal poly(N-isopropylacrylamide) pNIPAM gels. We use dissipative particle dynamics (DPD) to simulate the steady (slow heating rates) and unsteady (fast heating rates) de-swelling behavior of these thermo-sensitive gels. Our simulations show that for slow heating rates the aspect ratio of the tori remains constant during de-swelling. For rapid heating rates we observe buckling instabilities. Our simulations agree with the experimental observations. Financial support by NSF CAREER Award DMR-1255288 is gratefully acknowledged.

  7. The Virtual-casing Principle For 3D Toroidal Systems

    SciTech Connect

    Lazerson, Samuel A.

    2014-02-24

    The capability to calculate the magnetic field due to the plasma currents in a toroidally confined magnetic fusion equilibrium is of manifest relevance to equilibrium reconstruction and stellarator divertor design. Two methodologies arise for calculating such quantities. The first being a volume integral over the plasma current density for a given equilibrium. Such an integral is computationally expensive. The second is a surface integral over a surface current on the equilibrium boundary. This method is computationally desirable as the calculation does not grow as the radial resolution of the volume integral. This surface integral method has come to be known as the "virtual-casing principle". In this paper, a full derivation of this method is presented along with a discussion regarding its optimal application.

  8. Quasars: a supermassive rotating toroidal black hole interpretation

    NASA Astrophysics Data System (ADS)

    Spivey, R. J.

    2000-08-01

    A supermassive rotating toroidal black hole (TBH) is proposed as the fundamental structure of quasars and other jet-producing active galactic nuclei. Rotating protogalaxies gather matter from the central gaseous region leading to the birth of massive toroidal stars, the internal nuclear reactions of which proceed very rapidly. Once the nuclear fuel is spent, gravitational collapse produces a slender ring-shaped TBH remnant. Transitory electron and neutron degeneracy stabilized collapse phases, although possible, are unlikely owing to the large masses involved thus these events are typically the first supernovae of the host galaxies. Given time, the TBH mass increases through continued accretion by several orders of magnitude, the event horizon swells whilst the central aperture shrinks. The difference in angular velocities between the accreting matter and the TBH induces a magnetic field that is strongest in the region of the central aperture and innermost ergoregion. Owing to the presence of negative energy states when such a gravitational vortex is immersed in an electromagnetic field, circumstances are near ideal for energy extraction via non-thermal radiation including the Penrose process and superradiant scattering. This establishes a self-sustaining mechanism whereby the transport of angular momentum away from the quasar by relativistic bi-directional jets reinforces both the modulating magnetic field and the TBH/accretion disc angular velocity differential. Continued mass-capture by the TBH results in contraction of the central aperture until the TBH topology transitions to being spheroidal, extinguishing quasar behaviour. Similar mechanisms may be operating in microquasars, supernovae and sources of repeating gamma-ray bursts when neutron density or black hole tori arise. Long-term TBH stability seems to require either a negative cosmological constant, a non-stationary space-time resulting from the presence of accreting matter or the intervention of quantum

  9. Transport, Equilibrium, and Stability of a Toroidal Edge Plasma

    NASA Astrophysics Data System (ADS)

    McCarthy, Daniel Raymund

    The stability and transport of the drift resistive ballooning mode (DRBM) and its impact on the dynamics of a toroidal edge plasma is studied. The linear stability of the DRBM is calculated analytically and numerically, and is found to be unstable over a broad range of mode numbers. The nonlinear dynamics of the mode were studied using a fully nonlinear, three dimensional finite difference code. It was found that the saturated turbulent transport was anomalously large and exhibited a large ballooning -like poloidal asymmetry. The growth and saturation of this mode occurred on the time scale t_ {B} = (c_{s}/sqrt{RL _{n}})^{-1}.. Nonlinear two dimensional axisymmetric toroidal simulations of a tokamak edge and scrape off layer were performed to study the effect of this transport on the edge dynamics. Large parallel flows of order the local sound speed c_{s} were generated on the longer time scale t_{s } = (c_{s}/qR)^ {-1}. The stability of this 'equilibrium' depends upon the parameter alpha equiv rho_{s}qR/aL_{r}. For alpha << 1, the edge was unstable to the Stringer spin up instability. For weak magnetic pumping (H-mode), a poloidal rotation of order the poloidal sound speed ac_{s }/qR was generated in the electron diamagnetic drift direction. For strong pumping (L-mode), the rotation opposed the ion diamagnetic drift. The impact of particle sources at various poloidal locations was also studied. For alpha > 1 the edge was unstable to the parallel velocity shear instability. The turbulence gave order unity fluctuation levels and was localized inside the last closed flux surface and on the inner side of the torus.

  10. MHD Stability Analysis Using an X-ray Wave Array Diagnostic on the PEGASUS Toroidal Experiment*

    NASA Astrophysics Data System (ADS)

    Wilson, C.; Fonck, R.; Intrator, T.; Thorson, T.

    1998-11-01

    Tearing mode instabilities during plasma current ramp-up are important for extremely low aspect ratio devices. Fast current ramping, aided by the low internal inductance of low aspect ratio plasmas, induces skin currents. The resulting hollow current profile may produce double tearing modes, which allows for reconnection and current penetration. Another area of interest for MHD stability studies in the first phase of operation of the P EGASUS Experiment is the nature of the plasma stability boundary as the edge-q is lowered at extremely low aspect ratio. This boundary plays a major role in the accessibility to stable operation at very low toroidal field. P EGASUS will employ an X-ray diode (XRD) detector array to diagnose the internal plasma MHD structure. We are designing and installing a vertical 20 channel radially viewing pinhole array of XRD's for >= 50 eV photon measurement. Each channel will have a vertical resolution of 2 cm and an upper frequency limit of 100 kHz. The lithium drifted XRD's have a large surface area of 90 mm^2, thereby being quite sensitive and suited to a low temperature start-up plasma. The expected signal-to-noise ratio due to photon noise is < 0.1% for P EGASUS plasmas. * *Supported by U.S. DoE grant No. DE-FG02-96ER54375

  11. The Soft X-ray Flux Surface Shape Diagnostic on the PEGASUS Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Tritz, K. L.; Fonck, R. J.; Schooff, R. J.; Sontag, A. C.

    2000-10-01

    Flux surface shape information can be used as a constraint for reconstruction of the plasma current and q profiles for shaped, low-aspect ratio toroidal devices. To exploit this sensitivity of shape to plasma profiles, an equilibrium code was developed to incorporate flux surface shape information from linearized chordal soft X-ray (SXR) measurement inputs from a 2-D tangentially viewing pinhole camera. This equilibrium code uses a nonlinear least squares fitting to facilitate the inclusion of the SXR measurement constraints. The pinhole camera consists of a 2mm diameter pinhole projection onto a 150mm diameter viewport coated with a high-efficiency phosphor, P43. A 40mm diameter MCP image intensifier is lens coupled to the phosphor for maximum sensitivity, resulting in a signal to noise ratio of <1% from photon statistics. The MCP is optically coupled to a fast framing CCD camera allowing for frame rates of 1000 frames/sec. and exposure times < 100 μs. First results from a prototype system will be achieved with a commercial intensified camera.

  12. Initial Investigations of H-mode Edge Dynamics in the PEGASUS Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Bongard, M. W.; Fonck, R. J.; Thome, K. E.; Thompson, D. S.

    2013-10-01

    Experiments with ultra-low aspect ratio (A < 1 . 2) H-mode plasmas in PEGASUS enable unique measurements of Edge Localized Mode (ELM) phenomena of import to next-step fusion devices. The modest temperatures and pulse lengths in PEGASUS allow the use of insertable probes to diagnose the edge plasma with high spatial and temporal resolution. In particular, the compatibility of the Hall probe Jedge diagnostic with the H-mode edge to date affords the opportunity to study current profile dynamics throughout the ELM cycle. A pedestal in Jedge is formed following the L-H transition that is transiently destroyed during ELMs. Presently, Type I and Type III ELMs are accessible. Both types generate field-aligned filaments during the ELM. A prominent current-hole Jedge perturbation and low- n MHD signature is evident during Type III ELM crash events, similar to that seen in prior peeling mode studies conducted in L-mode with strong edge current drive. In contrast, Type I ELMs are found to have a complex MHD signature comprised of multiple intermediate toroidal mode numbers (5 < n < 15) , a steepening of the Jedge gradient scale length as well as a slight hump in Jedge , which is consistent with a peeling-ballooning nature and the presence of bootstrap current drive. Particle trapping and associated neoclassical effects are expected to be large in PEGASUS plasmas at A ~ 1, even with modest pedestal parameters. Work supported by US DOE Grant DE-FG02-96ER54375.

  13. Self-consistent Equilibrium Model of Low-aspect-ratio Toroidal Plasma with Energetic Beam Ions

    SciTech Connect

    E.V. Belova; N.N. Gorelenkov; C.Z. Cheng

    2003-04-09

    A theoretical model is developed which allows the self-consistent inclusion of the effects of energetic beam ions in equilibrium calculations of low-aspect-ratio toroidal devices. A two-component plasma is considered, where the energetic ions are treated using a kinetic Vlasov description, while a one-fluid magnetohydrodynamic description is used to represent the thermal plasma. The model allows for an anisotropic distribution function and a large Larmor radius of the beam ions. Numerical results are obtained for neutral-beam-heated plasmas in the National Spherical Torus Experiment (NSTX). Self-consistent equilibria with an anisotropic fast-ion distribution have been calculated for NSTX. It is shown for typical experimental parameters that the contribution of the energetic neutral-beam ions to the total current can be comparable to that of the background plasma, and that the kinetic modifications of the equilibrium can be significant. The range of validity of the finite-Larmor-radius expansion and of the reduced kinetic descriptions for the beam ions in NSTX is discussed. The calculated kinetic equilibria can be used for self-consistent numerical studies of beam-ion-driven instabilities in NSTX.

  14. Design and implementation of a multichannel millimeter wave interferometer for the Compact Toroidal Hybrid experiment

    SciTech Connect

    Miller, M. C.; Hanson, J. D.; Hartwell, G. J.; Knowlton, S. F.; Maurer, D. A.; Stevenson, B. A.

    2012-10-15

    A three-channel 1 mm wave interferometer has been designed, assembled, and installed on the Compact Toroidal Hybrid torsatron (CTH). The interferometer design makes novel use of a subharmonic mixer for detection, which simplifies alignment. It employs a single electronically tunable source that is repetitively chirped using a sawtooth waveform of frequency up to 1 MHz. The 15.25 GHz drive oscillator is multiplied in two stages to 122 GHz before a final doubler stage brings it to 244 GHz. Local oscillator (LO) power at 122 GHz is directed through waveguide to the LO input of the subharmonic mixer of each viewing chord, simplifying alignment. Phase detection is performed by directly digitizing the amplified mixer outputs at 50 MHz and processing them with a software algorithm. Initial measurements made with the central chord of the new interferometer agree with those from the existing 4 mm system at low densities. The 1 mm system performs well in current-driven discharges reaching densities over 10{sup 19} m{sup -3}, whereas the lower frequency interferometer is found to be less reliable due to loss of fringes. This is a critical improvement for experiments studying the onset, avoidance, and vacuum magnetic transform dependence of disruptions in the CTH device.

  15. High-performance TF coil design for the Toroidal Fusion Core Experiment (TFCX)

    NASA Astrophysics Data System (ADS)

    Strivastava, V. C.

    1984-09-01

    The Toroidal Fusion Core Experiment (RFCX) is a proposed concept for an ignited, long-pulse, current-driven Tokamak device. The TF coil winding cross section in the inboard region is impacted by peak field 10 T, winding current density approx. 3500 A/cm(2), and peak nuclear heating rates 50 mW/cc. The winding utilizes a Nb3Sn internally cooled cable superconductor (ICCS), which is a modified version of the conductor used in the Westinghouse LCP coil. These modifications include the increase of void fraction from 32% to 41% of the cable space for withstanding higher nuclear heating rates and a thicker conduit wall to carry larger magnetic loads. The critical current of an Nb3Sn conductor is strongly dependent on strain in the superconducting strands. The strain in strands is lower when the windings are: (1) wound and then reacted (W/R), as compared to (2) reacted and then wound (R/W). The impact of these approaches on winding performance is discussed. The windings are pancake wound and cooled with supercritical helium. The LHe inlet (approx. 4 K) and outlet (approx. 5.5 K) connections are located on the sides of the TF coils. The conductor design, the winding design, and performance analysis are described.

  16. Continuum absorption in the vicinity of the toroidicity-induced Alfvén gap

    NASA Astrophysics Data System (ADS)

    Li, M.; Breizman, B. N.; Zheng, L. J.; Chen, Eugene Y.

    2015-12-01

    Excitation of Alfvén modes is commonly viewed as a concern for energetic particle confinement in burning plasmas. The 3.5 MeV alpha particles produced by fusion may be affected as well as other fast ions in both present and future devices. Continuum damping of such modes is one of the key factors that determine their excitation thresholds and saturation levels. This work examines the resonant dissipative response of the Alfvén continuum to an oscillating driving current when the driving frequency is slightly outside the edges of the toroidicity-induced spectral gap. The problem is largely motivated by the need to describe the continuum absorption in the frequency sweeping events. A key element of this problem is the negative interference of the two closely spaced continuum crossing points. We explain why the lower and upper edges of the gap can have very different continuum absorption features. The difference is associated with an eigenmode whose frequency can be arbitrarily close to the upper edge of the gap whereas the lower edge of the gap is always a finite distance away from the closest eigenmode.

  17. Design and implementation of a multichannel millimeter wave interferometer for the Compact Toroidal Hybrid experiment.

    PubMed

    Miller, M C; Hanson, J D; Hartwell, G J; Knowlton, S F; Maurer, D A; Stevenson, B A

    2012-10-01

    A three-channel 1 mm wave interferometer has been designed, assembled, and installed on the Compact Toroidal Hybrid torsatron (CTH). The interferometer design makes novel use of a subharmonic mixer for detection, which simplifies alignment. It employs a single electronically tunable source that is repetitively chirped using a sawtooth waveform of frequency up to 1 MHz. The 15.25 GHz drive oscillator is multiplied in two stages to 122 GHz before a final doubler stage brings it to 244 GHz. Local oscillator (LO) power at 122 GHz is directed through waveguide to the LO input of the subharmonic mixer of each viewing chord, simplifying alignment. Phase detection is performed by directly digitizing the amplified mixer outputs at 50 MHz and processing them with a software algorithm. Initial measurements made with the central chord of the new interferometer agree with those from the existing 4 mm system at low densities. The 1 mm system performs well in current-driven discharges reaching densities over 10(19) m(-3), whereas the lower frequency interferometer is found to be less reliable due to loss of fringes. This is a critical improvement for experiments studying the onset, avoidance, and vacuum magnetic transform dependence of disruptions in the CTH device. PMID:23126990

  18. Thomson scattering diagnostic system design for the Compact Toroidal Hybrid experiment

    SciTech Connect

    Traverso, P. J. Maurer, D. A.; Ennis, D. A.; Hartwell, G. J.; Goforth, M. M.; Loch, S. D.; Pearce, A. J.; Cianciosa, M. R.

    2014-11-15

    A new Thomson scattering system using standard commercially available components has been designed for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH). The beam, generated by a frequency doubled Continuum PL DLS 2 J Nd:YAG laser, is passed vertically through an entrance Brewster window and an aperturing baffle system to minimize the stray laser light that could enter the collection optics. The beam line has been designed with an 8 m propagation distance to the mid-plane of the CTH device with the beam diameter kept less than 3 mm inside the plasma volume. The beam exits the vacuum system through another Brewster window and enters a beam dump, again to minimize the stray light in the vacuum chamber. Light collection, spectral processing, and signal detection are accomplished with an f/#∼ 1 aspheric lens, a commercially available Holospec f/1.8 spectrometer, and an Andor iStar DH740-18U-C3 image intensified camera. Spectral rejection of stray laser light, if needed, can be performed with the use of an optional interference filter at the spectrometer input. The system has been developed for initial single point measurements of plasmas with core electron temperatures of approximately 20–300 eV and densities of 5 × 10{sup 18} to 5 × 10{sup 19} m{sup −3} dependent upon operational scenario.

  19. Thomson scattering diagnostic system design for the Compact Toroidal Hybrid experimenta)

    NASA Astrophysics Data System (ADS)

    Traverso, P. J.; Maurer, D. A.; Ennis, D. A.; Hartwell, G. J.; Goforth, M. M.; Loch, S. D.; Pearce, A. J.; Cianciosa, M. R.

    2014-11-01

    A new Thomson scattering system using standard commercially available components has been designed for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH). The beam, generated by a frequency doubled Continuum PL DLS 2 J Nd:YAG laser, is passed vertically through an entrance Brewster window and an aperturing baffle system to minimize the stray laser light that could enter the collection optics. The beam line has been designed with an 8 m propagation distance to the mid-plane of the CTH device with the beam diameter kept less than 3 mm inside the plasma volume. The beam exits the vacuum system through another Brewster window and enters a beam dump, again to minimize the stray light in the vacuum chamber. Light collection, spectral processing, and signal detection are accomplished with an f/{#} ˜ 1 aspheric lens, a commercially available Holospec f/1.8 spectrometer, and an Andor iStar DH740-18U-C3 image intensified camera. Spectral rejection of stray laser light, if needed, can be performed with the use of an optional interference filter at the spectrometer input. The system has been developed for initial single point measurements of plasmas with core electron temperatures of approximately 20-300 eV and densities of 5 × 1018 to 5 × 1019 m-3 dependent upon operational scenario.

  20. Thomson scattering diagnostic system design for the Compact Toroidal Hybrid experiment.

    PubMed

    Traverso, P J; Maurer, D A; Ennis, D A; Hartwell, G J; Goforth, M M; Loch, S D; Pearce, A J; Cianciosa, M R

    2014-11-01

    A new Thomson scattering system using standard commercially available components has been designed for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH). The beam, generated by a frequency doubled Continuum PL DLS 2 J Nd:YAG laser, is passed vertically through an entrance Brewster window and an aperturing baffle system to minimize the stray laser light that could enter the collection optics. The beam line has been designed with an 8 m propagation distance to the mid-plane of the CTH device with the beam diameter kept less than 3 mm inside the plasma volume. The beam exits the vacuum system through another Brewster window and enters a beam dump, again to minimize the stray light in the vacuum chamber. Light collection, spectral processing, and signal detection are accomplished with an f/#∼ 1 aspheric lens, a commercially available Holospec f/1.8 spectrometer, and an Andor iStar DH740-18U-C3 image intensified camera. Spectral rejection of stray laser light, if needed, can be performed with the use of an optional interference filter at the spectrometer input. The system has been developed for initial single point measurements of plasmas with core electron temperatures of approximately 20-300 eV and densities of 5 × 10(18) to 5 × 10(19) m(-3) dependent upon operational scenario. PMID:25430265

  1. Continuum absorption in the vicinity of the toroidicity-induced Alfvén gap

    SciTech Connect

    Li, M.; Breizman, B. N.; Zheng, L. J.; Chen, Eugene Y.

    2015-12-04

    Excitation of Alfvén modes is commonly viewed as a concern for energetic particle confinement in burning plasmas. The 3.5 MeValpha particles produced by fusion may be affected as well as other fast ions in both present and future devices. Continuum damping of such modes is one of the key factors that determine their excitation thresholds and saturation levels. This work examines the resonant dissipative response of the Alfvén continuum to an oscillating driving current when the driving frequency is slightly outside the edges of the toroidicity-induced spectral gap. The problem is largely motivated by the need to describe the continuum absorption in the frequency sweeping events. Akey element of this problem is the negative interference of the two closely spaced continuum crossing points.Weexplain why the lower and upper edges of the gap can have very different continuum absorption features. Lastly, the difference is associated with an eigenmode whose frequency can be arbitrarily close to the upper edge of the gap whereas the lower edge of the gap is always a finite distance away from the closest eigenmode.

  2. Continuum absorption in the vicinity of the toroidicity-induced Alfvén gap

    DOE PAGESBeta

    Li, M.; Breizman, B. N.; Zheng, L. J.; Chen, Eugene Y.

    2015-12-04

    Excitation of Alfvén modes is commonly viewed as a concern for energetic particle confinement in burning plasmas. The 3.5 MeValpha particles produced by fusion may be affected as well as other fast ions in both present and future devices. Continuum damping of such modes is one of the key factors that determine their excitation thresholds and saturation levels. This work examines the resonant dissipative response of the Alfvén continuum to an oscillating driving current when the driving frequency is slightly outside the edges of the toroidicity-induced spectral gap. The problem is largely motivated by the need to describe the continuummore » absorption in the frequency sweeping events. Akey element of this problem is the negative interference of the two closely spaced continuum crossing points.Weexplain why the lower and upper edges of the gap can have very different continuum absorption features. Lastly, the difference is associated with an eigenmode whose frequency can be arbitrarily close to the upper edge of the gap whereas the lower edge of the gap is always a finite distance away from the closest eigenmode.« less

  3. Experimental investigation of plasma flows in open trap with toroidal diverter under ECR discharge

    SciTech Connect

    Berezkin, A. V. Bragin, E. Yu. Zhil’tsov, V. A. Kulygin, V. M. Yanchenkov, S. V.

    2015-12-15

    The results of experimental investigations of plasma flows from an open trap with a toroidal diverter are presented. Cold plasma is generated when introducing microwave power under conditions of electron cyclotron resonance (ECR). The radiation is introduced by a waveguide through a vacuum-tight ceramic window across the axis of the device. By means of the Langmuir probes, the spatial distributions of plasma parameters are measured. The highest density is limited to a critical value n{sub c} (∼10{sup 12} cm{sup –3}) for the generator frequency under use. It is found that the temperature and density of the plasma in the trap and in escaping flows are almost independent of the radius when the ECR zone is located near the open-trap confinement region and the density is close to n{sub c}. At the density n < n{sub c}, ring plasma structures, which collapse under the action of a low-frequency instability, are observed near the separatrix. The possible mechanisms of the occurrence of plasma structures and the nature of the plasma streams are discussed.

  4. Super-X divertors and high power density fusion devices

    SciTech Connect

    Valanju, P. M.; Kotschenreuther, M.; Mahajan, S. M.; Canik, J.

    2009-05-15

    The Super-X Divertor (SXD), a robust axisymmetric redesign of the divertor magnetic geometry that can allow a fivefold increase in the core power density of toroidal fusion devices, is presented. With small changes in poloidal coils and currents for standard divertors, the SXD allows the largest divertor plate radius inside toroidal field coils. This increases the plasma-wetted area by 2-3 times over all flux-expansion-only methods (e.g., plate near main X point, plate tilting, X divertor, and snowflake), decreases parallel heat flux and hence plasma temperature at plate, and increases connection length by 2-5 times. Examples of high-power-density fusion devices enabled by SXD are discussed; the most promising near-term device is a 100 MW modular compact fusion neutron source 'battery' small enough to fit inside a conventional fission blanket.

  5. Steady state toroidal magnetic field at earth's core-mantle boundary

    NASA Technical Reports Server (NTRS)

    Levy, Eugene H.; Pearce, Steven J.

    1991-01-01

    Measurements of the dc electrical potential near the top of earth's mantle have been extrapolated into the deep mantle in order to estimate the strength of the toroidal magnetic field component at the core-mantle interface. Recent measurements have been interpreted as indicating that at the core-mantle interface, the magnetic toroidal and poloidal field components are approximately equal in magnitude. A motivation for such measurements is to obtain an estimate of the strength of the toroidal magnetic field in the core, a quantity important to our understanding of the geomagnetic field's dynamo generation. Through the use of several simple and idealized calculation, this paper discusses the theoretical relationship between the amplitude of the toroidal magnetic field at the core-mantle boundary and the actual amplitude within the core. Even with a very low inferred value of the toroidal field amplitude at the core-mantle boundary, (a few gauss), the toroidal field amplitude within the core could be consistent with a magnetohydrodynamic dynamo dominated by nonuniform rotation and having a strong toroidal magnetic field.

  6. Two-Dimensional Ballooning Transformation with Applications to Toroidal Alfven Eigenmodes.

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Dong

    A general formulation for high-n (n is the toroidal mode number) modes in an axisymmetric toroidal plasma is presented, based on the two dimensional (2-D) ballooning transformation. It is shown that this formulation is more general than the conventional ballooning theory, and reduces to the conventional theory in a special case. Toroidal Alfven waves are studied using the 2 -D ballooning formulation. A perturbation theory is systematically developed for the continuum damping of the toroidal Alfven eigenmode (TAE). A formula, similar to the Fermi golden rule for decaying systems in quantum mechanics, is derived for the continuum damping rate of the TAE; the decay (damping) rate is expressed explicitly in terms of the coupling of the TAE to the continuum spectrum. Numerical results are obtained and compared to previous calculations. Kinetic effects on toroidal Alfven waves are studied. Multiple -gap coupling is included automatically by the 2-D ballooning formulation. A new branch of modes, the kinetic toroidal Alfven eigenmodes (KTAE), emerges as a result of kinetic effects. This mode resides just above the toroidal shear Alfven gap, and has a structure similar to the TAE. Numerical results for the kinetic damping rates for the TAE and the KTAE are obtained, and multiple-gap coupling effects are studied by comparing with the single gap theory of Mett and Mahajan (Phys. Fluids B 4 2885 (1992)).

  7. A convergence study for the Laguerre expansion in the moment equation method for neoclassical transport in general toroidal plasmas

    SciTech Connect

    Nishimura, S.; Sugama, H.; Maassberg, H.; Beidler, C. D.; Murakami, S.; Nakamura, Y.; Hirooka, S.

    2010-08-15

    The dependence of neoclassical parallel flow calculations on the maximum order of Laguerre polynomial expansions is investigated in a magnetic configuration of the Large Helical Device [S. Murakami, A. Wakasa, H. Maassberg, et al., Nucl. Fusion 42, L19 (2002)] using the monoenergetic coefficient database obtained by an international collaboration. On the basis of a previous generalization (the so-called Sugama-Nishimura method [H. Sugama and S. Nishimura, Phys. Plasmas 15, 042502 (2008)]) to an arbitrary order of the expansion, the 13 M, 21 M, and 29 M approximations are compared. In a previous comparison, only the ion distribution function in the banana collisionality regime of single-ion-species plasmas in tokamak configurations was investigated. In this paper, the dependence of the problems including electrons and impurities in the general collisionality regime in an actual nonsymmetric toroidal configuration is reported. In particular, qualities of approximations for the electron distribution function are investigated in detail.

  8. Identification of Optical Component of North Toroidal Source of Sporadic Meteors and its Origin

    NASA Technical Reports Server (NTRS)

    Hashimoto, T.; Watanabe, J.; Sato, M.; Ishiguro, M.

    2011-01-01

    We succeeded to identify the North Toroidal source by optical observations performed by the SonotaCo Network, which is a TV observation network coordinated by Japanese amateurs. This source has been known only for radar observations until now. The orbits of the optical meteors in the North Toroidal source are relatively large eccentricity and semi-major axis, compared with those of the radar meteors. In this paper, we report the characteristics of this North Toroidal source detected by optical observations, and discuss the possible origin and evolution of this source.

  9. Multiplicity of low-shear toroidal Alfvén eigenmodes

    NASA Astrophysics Data System (ADS)

    Candy, J.; Breizman, B. N.; Van Dam, J. W.; Ozeki, T.

    1996-02-01

    An enlarged spectrum of ideal toroidal Alfvén eigenmodes is demonstrated to exist within a toroidicity-induced Alfvén gap when the inverse aspect ratio is comparable to or larger than the value of the magnetic shear. This limit is appropriate for the low-shear region in most tokamaks, especially those with low aspect ratio. The new modes may be destabilized by fusion-product alpha particles more easily than the standard toroidal Alfvén eigenmodes.

  10. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    DOE PAGESBeta

    Staszczak, A.; Wong, Cheuk-Yin

    2016-05-11

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28 A 52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114 and 140, which follow the same (multi-particle) (multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

  11. Dynamics of toroidal spiral strings around five-dimensional black holes

    SciTech Connect

    Igata, Takahisa; Ishihara, Hideki

    2010-02-15

    We examine the separability of the Nambu-Goto equation for test strings in a shape of toroidal spiral in a five-dimensional Kerr-AdS black hole. In particular, for a 'Hopf loop' string which is a special class of the toroidal spiral strings, we show the complete separation of variables occurs in two cases, Kerr background and Kerr-AdS background with equal angular momenta. We also obtain the dynamical solution for the Hopf loop around a black hole and for the general toroidal spiral in Minkowski background.

  12. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    NASA Astrophysics Data System (ADS)

    Staszczak, Andrzej; Wong, Cheuk-Yin

    2016-05-01

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28≤A≤52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114ħ and 140ħ, which follow the same (multi-particle)-(multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

  13. Reduced-magnetohydrodynamic simulations of toroidally and poloidally localized edge localized modes

    SciTech Connect

    Hoelzl, M.; Guenter, S.; Mueller, W.-C.; Lackner, K.; Krebs, I.; Wenninger, R. P.; Huysmans, G. T. A.; Collaboration: ASDEX Upgrade Team

    2012-08-15

    We use the non-linear reduced-magnetohydrodynamic code JOREK to study edge localized modes (ELMs) in the geometry of the ASDEX Upgrade tokamak. Toroidal mode numbers, poloidal filament sizes, and radial propagation speeds of filaments into the scrape-off layer are in good agreement with observations for type-I ELMs in ASDEX Upgrade. The observed instabilities exhibit a toroidal and poloidal localization of perturbations which is compatible with the 'solitary magnetic perturbations' recently discovered in ASDEX Upgrade [R. Wenninger et al., 'Solitary magnetic perturbations at the ELM onset,' Nucl. Fusion (accepted)]. This localization can only be described in numerical simulations with high toroidal resolution.

  14. HIDRA: A new device for PFC and PMI development

    NASA Astrophysics Data System (ADS)

    Andruczyk, Daniel; Ruzic, David N.; Allain, Jean Paul; Curreli, Davide; HIDRA Team

    2014-10-01

    A toroidal plasma device is being constructed at the University of Illinois dedicated in part as a toroidal liquid-metal PFC technology test bench. The Hybrid Illinois stellarator/tokamak Device for Research and Applications (HIDRA) is a medium sized classical stellarator (previously WEGA, IPP Greifswald) with, R = 0.72 m, a = 0.19 m, B < 0.5 T and will be able to reach Te = 10-50 eV, ne = 1017--1018 m-3 with plasmas running up to several minutes. A critical knowledge gap for liquid-metal PFCs is their integration and performance in asymmetric confinement fusion environments. HIDRA will be used to evaluate technologies such as TEMHD driven flows for the first wall, help address key questions including whether a full toroidal liquid-metal loop can operate in a toroidal machine, test low recycling regimes and whether D can be removed and recycled easily. Also, UIUC's experience with in-situ diagnostics will open up new opportunities for innovative Material Application Testing (HIDRA-MAT).

  15. Design and manufacture of a toroidal-type SMES for combination with real-time digital simulator (RTDS)

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-min; Kim, A.-Rong; Park, Minwon; Yu, In-Keun; Eom, Bum-Yong; Sim, Kidoek; Kim, Seok-Ho; Sohn, Myung-Hwan; Kim, Hae-Jong; Bae, Joon-Han; Seong, Ki-Cheol

    2011-06-01

    The authors designed and manufactured a toroidal-type superconducting magnetic energy storage (SMES) system. The toroidal-type SMES was designed using a 3D CAD program. The toroidal-type magnet consists of 30 double pancake coils (DPCs). The single pancake coils (SPCs), which constitute the double pancake coils, are arranged at an angle of 6° from each other, based on the central axis of the toroidal-type magnet. The cooling method used for the toroidal-type SMES is the conduction cooling type. When the cooling method for the toroidal-type SMES was designed, the two-stage Gifford-McMahon (GM) refrigerator was considered. The Bi-2223 HTS wire, which was made by soldering brass on both sides of the superconductor, is used for the magnet winding. Finally, the authors connected the toroidal-type SMES to a real-time digital simulator (RSCAD/RTDS) to simulate voltage sag compensation in a power utility.

  16. EMC3-EIRENE modelling of toroidally-localized divertor gas injection experiments on Alcator C-Mod

    SciTech Connect

    Lore, Jeremy D.; Reinke, M. L.; LaBombard, Brian; Lipschultz, B.; Churchill, R. M.; Pitts, R. A.; Feng, Y.

    2014-09-30

    Experiments on Alcator C-Mod with toroidally and poloidally localized divertor nitrogen injection have been modeled using the three-dimensional edge transport code EMC3-EIRENE to elucidate the mechanisms driving measured toroidal asymmetries. In these experiments five toroidally distributed gas injectors in the private flux region were sequentially activated in separate discharges resulting in clear evidence of toroidal asymmetries in radiated power and nitrogen line emission as well as a ~50% toroidal modulation in electron pressure at the divertor target. The pressure modulation is qualitatively reproduced by the modelling, with the simulation yielding a toroidal asymmetry in the heat flow to the outer strike point. Finally, toroidal variation in impurity line emission is qualitatively matched in the scrape-off layer above the strike point, however kinetic corrections and cross-field drifts are likely required to quantitatively reproduce impurity behavior in the private flux region and electron temperatures and densities directly in front of the target.

  17. EMC3-EIRENE modeling of toroidally-localized divertor gas injection experiments on Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Lore, J. D.; Reinke, M. L.; LaBombard, B.; Lipschultz, B.; Churchill, R. M.; Pitts, R. A.; Feng, Y.

    2015-08-01

    Experiments on Alcator C-Mod with toroidally and poloidally localized divertor nitrogen injection have been modeled using the three-dimensional edge transport code EMC3-EIRENE to elucidate the mechanisms driving measured toroidal asymmetries. In these experiments five toroidally distributed gas injectors in the private flux region were sequentially activated in separate discharges resulting in clear evidence of toroidal asymmetries in radiated power and nitrogen line emission as well as a ∼50% toroidal modulation in electron pressure at the divertor target. The pressure modulation is qualitatively reproduced by the modeling, with the simulation yielding a toroidal asymmetry in the heat flow to the outer strike point. Toroidal variation in impurity line emission is qualitatively matched in the scrape-off layer above the strike point, however kinetic corrections and cross-field drifts are likely required to quantitatively reproduce impurity behavior in the private flux region and electron temperatures and densities directly in front of the target

  18. An Algorithm to Generate Toroidal and Helical CAGE Structures Using Pentagons, Hexagons and Heptagons

    NASA Astrophysics Data System (ADS)

    Yazgan, Efe; Taşci, Emre; Erkoç, Şakir

    An algorithm to generate toroidal or helical cage structures has been developed. Any toroidal or helical structure can be generated following four stages. In the first stage a Fonseca type unit cell and its symmetrical counterpart is formed which represents one-fifth of a toroid. In the second stage one-fifth fragment of the torus is fully obtained by applying geometry optimization to the structure obtained in the first stage. In the third stage the torus fragment obtained in the second stage is reproduced five times and connected to each other to generate either toroidal or helical structure. In the last stage a final optimization process is reapplied to get the complete structure desired.

  19. On the Grad-Shafranov reconstruction of toroidal magnetic flux ropes

    NASA Astrophysics Data System (ADS)

    Hu, Qiang

    2016-03-01

    We report briefly the technical approach of the Grad-Shafranov (GS) reconstruction of toroidal magnetic flux ropes, and present a case study of a multi-spacecraft magnetic cloud event on 20 November 2007.

  20. The role of toroidal magnetic field on the Rossby wave instability

    NASA Astrophysics Data System (ADS)

    Gholipour, Mahmoud; Nejad-Asghar, Mohsen

    2015-05-01

    In the accretion discs, the toroidal magnetic fields and viscous stresses are directly connected to each other, because generation of the large-scale toroidal magnetic fields are produced by the magnetohydrodynamic (MHD) turbulence. Gholipour & Nejad-Asghar have recently shown that the effect of high turbulent viscosity on the Rossby wave instability (RWI) is important, while the effect of low turbulent viscosity can be ignored. In this paper, in addition of turbulent viscosity, we investigate the role of toroidal magnetic field on the non-axisymmetric RWI in the self-gravitating accretion discs. We use a numerical method to investigate stable and unstable modes. The results show that the perturbations of Rossby waves will be damped by both the viscosity and toroidal magnetic field, while the magnetic diffusivity acts vice versa. Also, occurrence of RWI depends on the turbulent magnetic Prandtl number (i.e. ratio of the turbulent viscosity to the turbulent magnetic diffusivity).

  1. Design and characterization of a novel toroidal split-ring resonator

    NASA Astrophysics Data System (ADS)

    Bobowski, J. S.; Nakahara, Hiroko

    2016-02-01

    The design and characterization of a novel toroidal split-ring resonator (SRR) are described in detail. In conventional cylindrical SRRs, there is a large magnetic flux within the bore of the resonator. However, there also exists a non-negligible magnetic flux in the free space surrounding the resonator. The energy losses associated with this radiated power diminish the resonator's quality factor. In the toroidal SRR, on the other hand, the magnetic field lines are strongly confined within the bore of the resonator resulting in high intrinsic quality factors and stable resonance frequencies without requiring additional electromagnetic shielding. This paper describes the design and construction of a toroidal SRR as well as an experimental investigation of its cw response in the frequency-domain and its time-domain response to a rf pulse. Additionally, the dependence of the toroidal SRR's resonant frequency and quality factor on the strength of inductive coupling to external circuits is investigated both theoretically and experimentally.

  2. Toroidal rotation of multiple species of ions in tokamak plasma driven by lower-hybrid-waves

    SciTech Connect

    Zuo Yang; Wang Shaojie; Pan Chengkang

    2012-10-15

    A numerical simulation is carried out to investigate the toroidal rotation of multiple species of ions and the radial electric field in a tokamak plasma driven by the lower-hybrid-wave (LHW). The theoretical model is based on the neoclassical transport theory associated with the anomalous transport model. Three species of ions (primary ion and two species of impurity ions) are taken into consideration. The predicted toroidal velocity of the trace impurities during the LHW injection agrees reasonably well with the experimental observation. It is shown that the toroidal rotation velocities of the trace impurity ions and the primary ions are close, therefore the trace impurity ions are representative of the primary ions in the toroidal rotation driven by the LHW.

  3. Double-stranded DNA organization in bacteriophage heads: An alternative toroid-based model

    SciTech Connect

    Hud, N.V.

    1995-10-01

    Studies of the organization of double-stranded DNA within bacteriophage heads during the past four decades have produced a wealth of data. However, despite the presentation of numerous models, the true organization of DNA within phage heads remains unresolved. The observations of toroidal DNA structures in electron micrographs of phage lysates have long been cited as support for the organization of DNA in a spool-like fashion. This particular model, like all other models, has not been found to be consistent with all available data. Recently, the authors proposed that DNA within toroidal condensates produced in vitro is organized in a manner significantly different from that suggested by the spool model. This new toroid model has allowed the development of an alternative model for DNA organization within bacteriophage heads that is consistent with a wide range of biophysical data. Here the authors propose that bacteriophage DNA is packaged in a toroid that is folded into a highly compact structure.

  4. Toroids as NMR detectors in metal pressure probes and in flow systems

    DOEpatents

    Rathke, Jerome W.

    1991-01-01

    A nuclear magnetic resonance probe to measure the properties of a sample under high pressure conditions. The apparatus employs a free standing, elongated toroidal coil as the RF transmitter and receiver.

  5. From non- to super-radiating manipulation of a dipolar emitter coupled to a toroidal metastructure.

    PubMed

    Li, Jie; Xin, Xing-Xing; Shao, Jian; Wang, Ying-Hua; Li, Jia-Qi; Zhou, Lin; Dong, Zheng-Gao

    2015-11-16

    Toroidal dipolar response in a metallic metastructure, composed of double flat rings, is utilized to manipulate the radiation pattern of a single dipolar emitter (e.g., florescent molecule/atom or quantum dot). Strong Fano-type radiation spectrum can be obtained when these two coupling dipoles are spatially overlapped, leading to significant radiation suppression (so-called nonradiating source) attributed to the dipolar destructive interference. Moreover, this nonradiating configuration will become a directionally super-radiating nanoantenna after a radial displacement of the emitter with respect to the toroidal flat-ring geometry, which emits linearly polarized radiation with orders of power enhancement in a particular orientation. The demonstrated radiation characteristics from a toroidal-dipole-mediated dipolar emitter indicate a promising manipulation capability of the dipolar emission source by intriguing toroidal dipolar response. PMID:26698422

  6. A preliminary power consumption estimate for a toroid spoiler magnet proposed for the PWest upgrade

    SciTech Connect

    Kristalinski, A.L.

    1994-06-28

    The estimate is based on the preliminary magnet design provided by B. Lundberg. The required magnetic field induction in the winding carrying toroid leg is specified as an initial condition. Based on the cross section areas of the toroid legs the induction in all four toroid legs can be calculated. The particular type of steel which will be used is unknown so they used the curve on Fig. 2 for the most wide spread steels to obtain a field strength in the steel. The number of steel plates and accordingly the resulting technological air gap are unknown, therefore the calculation for two different gaps .25 mm and 2.5 mm were preformed. Results of the power consumption calculations for the proposed toroid spoiler magnet for different magnetic field induction values and two different air gaps are given. Operating costs for running the magnet are also given.

  7. Toroidal modeling of plasma response and resonant magnetic perturbation field penetration

    NASA Astrophysics Data System (ADS)

    Liu, Y. Q.; Kirk, A.; Sun, Y.; Cahyna, P.; Chapman, I. T.; Denner, P.; Fishpool, G.; Garofalo, A. M.; Harrison, J. R.; Nardon, E.; the MAST Team

    2012-12-01

    The penetration dynamics of the resonant magnetic perturbation (RMP) field is simulated in the full toroidal geometry, under realistic plasma conditions in MAST experiments. The physics associated with several aspects of the RMP penetration—the plasma response and rotational screening, the resonant and non-resonant torques and the toroidal momentum balance—are highlighted. In particular, the plasma response is found to significantly amplify the non-resonant component of the RMP field for some of the MAST plasmas. A fast rotating plasma, in response to static external magnetic fields, experiences a more distributed electromagnetic torque due to the resonance with continuum waves in the plasma. At fast plasma flow (such as for the MAST plasma), the electromagnetic torque is normally dominant over the neoclassical toroidal viscous (NTV) torque. However, at sufficiently slow plasma flow, the NTV torque can play a significant role in the toroidal momentum balance, thanks to the precession drift resonance enhanced, so-called superbanana plateau regime.

  8. On the Ideal Boundary Condition in a General Toroidal Geometry for a Mixed Magnetic Field Representation

    SciTech Connect

    X. Z. Tang

    2000-12-18

    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.

  9. Evolution of views on the structure of the ambipolar electric field in toroidal magnetic confinement systems

    SciTech Connect

    Kovrizhnykh, L. M.

    2015-12-15

    Various methods of determining the ambipolar electric field in toroidal magnetic systems (predominantly, in stellarators) and the evolution of views on this problem are discussed. Paradoxes encountered in solving this problem are analyzed, and ways of resolving them are proposed.

  10. On the development of a compact toroid injector at the University of Illinois at Urbana-Champaign

    NASA Astrophysics Data System (ADS)

    Christenson, Michael; Jung, Soonwook; Stemmley, Steven; Sang, Xia; Kalathiparambil, Kishor; Ruzic, David

    2015-11-01

    The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) device is a gas-puff driven, theta pinched, transient plasma source used to simulate extreme events incident on materials in the edge and divertor regions of a tokamak plasma. Previous work has shown that in its current form, TELS can bombard a target with a peak energy of 0.08 MJ m-2 over a 0.15 ms pulse, leading to a total heat flux of 0.5 GW m-2. While these values are sufficient to mimic Type 1 ELMs in smaller devices, the plasma energy of TELS must be improved by a factor of greater than two to adequately simulate larger-scale Type 1 ELMs. It is for this reason that modifications to the existing TELS device have been proposed in the form of developing a compact toroid (CT) injector since the new self-contained structure allows for higher densities and energies delivered onto a target. The new setup will use a bias field, generating a peak magnetic field greater than 0.1 T and a peak magnetic flux greater than 2 mWb, surrounding the existing plasma gun arrangement to create the CT and the existing theta pinch to compress and translate the plasmoid. Preliminary results and analyses are presented and discussed in relationship to interactions with both solid and liquid metal targets. Supported by DOE Grant DE-SC0008587.

  11. The turbulent diffusion of toroidal magnetic flux as inferred from properties of the sunspot butterfly diagram

    NASA Astrophysics Data System (ADS)

    Cameron, R. H.; Schüssler, M.

    2016-06-01

    Context. In order to match observed properties of the solar cycle, flux-transport dynamo models require the toroidal magnetic flux to be stored in a region of low magnetic diffusivity, typically located at or below the bottom of the convection zone. Aims: We infer the turbulent magnetic diffusivity affecting the toroidal field on the basis of empirical data. Methods: We considered the time evolution of mean latitude and width of the activity belts of solar cycles 12-23 and their dependence on cycle strength. We interpreted the decline phase of the cycles as a diffusion process. Results: The activity level of a given cycle begins to decline when the centers of its equatorward propagating activity belts come within their (full) width (at half maximum) from the equator. This happens earlier for stronger cycles because their activity belts are wider. From that moment on, the activity and the belt width decrease in the same manner for all cycles, independent of their maximum activity level. In terms of diffusive cancellation of opposite-polarity toroidal flux across the equator, we infer the turbulent diffusivity experienced by the toroidal field, wherever it is located, to be in the range 150-450 km2 s-1. Strong diffusive latitudinal spreading of the toroidal flux underneath the activity belts can be inhibited by an inflow toward the toroidal field bands in the convection zone with a magnitude of several meters per second. Conclusions: The inferred value of the turbulent magnetic diffusivity affecting the toroidal field agrees, to order of magnitude, with estimates based on mixing-length models for the solar convection zone. This is at variance with the requirement of flux-transport dynamo models. The inflows required to keep the toroidal field bands together before they approach the equator are similar to the inflows toward the activity belts observed with local helioseismology.

  12. Turbulent Transport in Fusion Plasmas, Effects of Toroidicity and Fluid Closure

    SciTech Connect

    Weiland, Jan

    2009-11-10

    Basic aspects of turbulent transport in toroidal magnetized plasmas are discussed. In particular Kadomtsev's mixing length estimate is found to work well for the Cyclone base case at the experimental gradient. Generalizations to include non-Markovian effects and off diagonal fluxes are given. The importance of toroidal effects is stressed These enter particularly strongly in convective or off diagonal fluxes. This feature applies also to momentum ttransport.

  13. The angular momentum transport by unstable toroidal magnetic fields

    NASA Astrophysics Data System (ADS)

    Rüdiger, G.; Gellert, M.; Spada, F.; Tereshin, I.

    2015-01-01

    We demonstrate with a nonlinear magnetohydrodynamic (MHD) code that angular momentum can be transported because of the magnetic instability of toroidal fields under the influence of differential rotation, and that the resulting effective viscosity may be high enough to explain the almost rigid-body rotation observed in radiative stellar cores. We only consider stationary, current-free fields, and only those combinations of rotation rates and magnetic field amplitudes which provide maximal numerical values of the viscosity. We find that the dimensionless ratio of the effective over molecular viscosity, νT/ν, linearly grows with the Reynolds number of the rotating fluid multiplied by the square-root of the magnetic Prandtl number, which is approximately unity for the considered red subgiant star KIC 7341231. For the interval of magnetic Reynolds numbers considered - which is restricted by numerical constraints of the nonlinear MHD code - the magnetic Prandtl number has a remarkable influence on the relative importance of the contributions of the Reynolds stress and the Maxwell stress to the total viscosity, which is magnetically dominated only for Pm ≳ 0.5. We also find that the magnetized plasma behaves as a non-Newtonian fluid, i.e., the resulting effective viscosity depends on the shear in the rotation law. The decay time of the differential rotation thus depends on its shear and becomes longer and longer during the spin-down of a stellar core.

  14. Commissioning of Thomson Scattering on the PEGASUS Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Schlossberg, D. J.; Fonck, R. J.; Peguero, L. M.; Winz, G. R.

    2013-10-01

    A new multipoint Thomson scattering diagnostic has been installed on the PEGASUS Toroidal Experiment. It employs a frequency-doubled Nd:YAG laser (λ0 = 532 nm) and spectrometers using volume phase holographic gratings and gated, intensified CCD cameras. Spectral, temporal and intensity calibrations of the spectrometer systems were conducted. Sources of laser energy loss were identified and reduced, beam termination was optimized to minimize reflections during collection time, and inter-shot alignment monitoring was installed. Rayleigh and Raman calibration efforts revealed significant stray light from in-vessel reflections; hence, a vacuum-compatible optical baffling system was designed, fabricated, and is being installed. Operation of the diagnostic will support characterization of helicity dissipation mechanisms and confinement scaling during local DC helicity injection startup on PEGASUS. Additionally, H-mode temperature and density profiles will be obtained to support equilibrium reconstructions and stability studies of ELMs in the H-mode plasma edge. Initial measurements will be conducted with an 8-spatial channel array; expansion to 24 channels is in progress. Work supported by US DOE Grant DE-FG02-96ER54375.

  15. Magnetic Equilibrium Studies on the PEGASUS Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Sontag, A.; Fonck, R.; Ono, M.; Thorson, T.; Tritz, K.

    1999-11-01

    Magnetic equilibrium analysis on the PEGASUS Toroidal Experiment is the basic tool used to study global plasma equilibrium and stability properties. Initial work is focusing on determination of macroscopic plasma parameters. To date, plasmas on the order of 0.1 MA with aspect ratios from 1.1 to 1.4 and elongations from 1 to >3 are under study. The magnetic reconstruction is accomplished using TokaMac, a plasma equilbrium reconstruction code, which incorporates measurements from a Rogowski loop, magnetic pickup coils, and flux loops. Time-evolving currents in the vacuum vessel wall are modeled as a set of mutually coupled axisymmetric current filaments. This model has been validated by comparison to magnetic probe measurements. To date, plasma-wall coupling is included using a single current filament model on the magnetic axis for the plasma current, and a distributed filament current model for the plasma current is under development. The wall current model code has been integrated with coil current measurements to specify the total externally applied field as input to the TokaMac magnetic equilibrium code.

  16. Magnetic Equilibrium Studies on the PEGASUS Toroidal Experiment*

    NASA Astrophysics Data System (ADS)

    Sontag, A.; Fonck, R.; Thorson, T.; Tritz, K.

    1998-11-01

    Magnetic equilibrium reconstruction is a fundamental tool for analyzing the plasma in P EGASUS . Initial interest is focused on macroscopic plasma parameters such as major radius (R), elongation (κ ), toroidal and poloidal beta, and internal plasma inductance. The lowest order reconstruction is accomplished using Tokamac, a magnetic equilibrium reconstruction code, which incorporates measurements from a Rogowski loop, radial and poloidal magnetic pickup coils, and flux loops. A series of model equilibria was generated to determine the minimal set of internal magnetic diagnostics necessary to accurately determine the parameters of interest. The availability of a wide range of plasma shapes and positions (κ ≈ 2-3 , R ≈ 0.25 - 0.45m, A ≈ 1.1 - 1.25) limits the location of the internal diagnostics. Initial operations and analysis will concentrate on ohmic discharges with short pulse duration (< 30 ms) and high current ramps ( ~ 10 MA/s). The conducting vacuum vessel wall complicates the magnetic analysis, requiring detailed accounting of the axisymmetric currents in the vessel wall. * *Supported by U.S. DoE grant No. DE-FG02-96ER54375

  17. Phase Relationships of Solar Hemispheric Toroidal and Poloidal Cycles

    NASA Astrophysics Data System (ADS)

    Muraközy, J.

    2016-08-01

    The solar northern and southern hemispheres exhibit differences in their intensities and time profiles of the activity cycles. The time variation of these properties was studied in a previous article covering the data from Cycles 12–23. The hemispheric phase lags exhibited a characteristic variation: the leading role was exchanged between hemispheres every four cycles. The present work extends the investigation of this variation using the data of Staudacher and Schwabe in Cycles 1–4 and 7–10 as well as Spörer’s data in Cycle 11. The previously observed variation cannot be clearly recognized using the data of Staudacher, Schwabe, and Spörer. However, it is more interesting that the phase lags of the reversals of the magnetic fields at the poles follow the same variations as those of the hemispheric cycles in Cycles 12–23, i.e., one of the hemispheres leads in four cyles and the leading role jumps to the opposite hemisphere in the next four cycles. This means that this variation is a long-term property of the entire solar dynamo mechanism, for both the toroidal and poloidal fields, which hints at an unidentified component of the process responsible for the long-term memory.

  18. Tokamak equilibria with toroidal current reversal: properties and computational issues

    SciTech Connect

    Rodrigues, Paulo; Bizarro, Joao P. S.

    2006-11-30

    Several properties of axisymmetric plasma equilibria with toroidal-current reversal (TCR) are discussed using some unifying concepts from catastrophe theory. Namely, those of structural stability of functions near critical points, singularity unfolding by small perturbations, and model parameter-space division by bifurcation sets are found to be of particular usefulness. Magnetic configurations displaying, simultaneously, TCR and nested flux surfaces are thence shown to be necessarily degenerate and structurally unstable, meaning that they are easily transformed into non-nested ones by small perturbations in the model parameter set. This should lead to a new paradigm when discussing TCR equilibria, as most of present knowledge relies mainly on the properties of nested solutions, which is expected to favor the study of the broader class of non-nested configurations that recently attracted a considerable discussion in the fusion community. In addition, it is also shown how TCR imposes some constraints on plasma profiles, and how these may be dealt with computationally while keeping the ability to manipulate the shape of the inner island system.

  19. LQR Controller for Toroidal Continuously Variable Transmission in Reverse Motion

    NASA Astrophysics Data System (ADS)

    Mensler, Michel; Kawabe, Taketoshi; Joe, Shinichiro

    The system considered in this paper is a Toroidal Continuously Variable Transmission (TCVT) system for cars. This system is unstable in reverse motion as some mechanical parts have been removed from the original one for cost reduction, and the gear ratio has to be regulated around its nominal value for car reverse motion. The control theory used here is the Linear Quadratic Regulator (LQR) associated to a gain-scheduling technique, as the TCVT system is nonlinear according to the car speed. Moreover, as the LQR method requires the entire TCVT state vector and as the only available signal is the gear ratio, a full-order observer is designed. In order to take the other nonlinearities of the system into account, the observer is nonlinear: a diffeomorphism is then used for converting the variables provided by the nonlinear observer into the needed variables. In order to verify the effectiveness and the robustness of the controller against the car speed and the torque shift disturbance phenomenon, several experiments with a test-bed and with an actual vehicle have been performed and showed the efficiency of the proposed controller.

  20. Wall conditioning and leak localization in the advanced toroidal facility

    SciTech Connect

    Langley, R.A.; Glowienka, J.C.; Mioduszewski, P.K.; Murakami, M.; Rayburn, T.F.; Simpkins, J.E.; Schwenterly, S.W.; Yarber, J.L.

    1989-01-01

    The Advanced Toroidal Facility (ATF) vacuum vessel and its internal components have been conditioned for plasma operation by baking, discharge cleaning with hydrogen and helium, and gettering with chromium and titanium. The plasma-facing surface of ATF consists mainly of stainless steel with some graphite; the outgassing area is dominated by the graphite because of its open porosity. Since this situation is somewhat different from that in other fusion plasma experiments, in which a single material dominates both the outgassing area and the plasma-facing area, different cleaning and conditioning techniques are required. The situation was aggravated by air leaks in the vacuum vessel, presumably resulting from baking and from vibration during plasma operation. The results of the various cleaning and conditioning techniques used are presented and compared on the basis of residual gas analysis and plasma performance. A technique for detecting leaks from the inside of the vacuum vessel is described; this technique was developed because access to the outside of the vessel is severely restricted by external components. 10 refs., 6 figs., 2 tabs.

  1. Deconfinement in Yang-Mills Theory through Toroidal Compactification

    SciTech Connect

    Simic, Dusan; Unsal, Mithat; /Stanford U., Phys. Dept. /SLAC

    2011-08-12

    We introduce field theory techniques through which the deconfinement transition of four-dimensional Yang-Mills theory can be moved to a semi-classical domain where it becomes calculable using two-dimensional field theory. We achieve this through a double-trace deformation of toroidally compactified Yang-Mills theory on R{sup 2} x S{sub L}{sup 1} x S{sub {beta}}{sup 1}. At large N, fixed-L, and arbitrary {beta}, the thermodynamics of the deformed theory is equivalent to that of ordinary Yang-Mills theory at leading order in the large N expansion. At fixed-N, small L and a range of {beta}, the deformed theory maps to a two-dimensional theory with electric and magnetic (order and disorder) perturbations, analogs of which appear in planar spin-systems and statistical physics. We show that in this regime the deconfinement transition is driven by the competition between electric and magnetic perturbations in this two-dimensional theory. This appears to support the scenario proposed by Liao and Shuryak regarding the magnetic component of the quark-gluon plasma at RHIC.

  2. Kinetic theory of toroidicity and ellipticity-induced Alfven eigenmodes

    NASA Astrophysics Data System (ADS)

    Mett, R. R.; Mahajan, S. M.

    1992-10-01

    Toroidicity-induced Alfven eigenmodes (TAE) and ellipticity-induced Alfven eigenmodes (EAE) are currently of great interest because they may destroy the confinement of fast ions in a burning tokamak plasma. The present study focuses on kinetic effects, extending the non-perturbative kinetic analysis of the TAE to the EAE. One finds that the parameter which measures the kinetic character of the EAE is significantly smaller than it is for the TAE for elongated plasmas like DIII-D. The parameter is rather small for the lower mode numbers but attains values of order unity or larger for the higher mode numbers, since the parameter scales as the square of the mode number. Consequently, one expects the lower mode number EAE's to have a strongly magnetohydrodynamic (MHD) character, and to suffer only perturbative damping that depends linearly on the dissipative mechanisms. However, while the former is true, the latter is not necessarily the case. This work examines these kinetic T/EAE(KT/EAE) modes in further detail.

  3. Extension of TFTR operations to higher toroidal field levels

    SciTech Connect

    Woolley, R.D.

    1995-12-31

    For the past year, TFTR has sometimes operated at extended toroidal field (TF) levels. The extension to 5.6 Tesla (79 kA) was crucial for TFTR`s November 1994 10.7 MW DT fusion power record. The extension to 6.0 Tesla (85 kA) was commissioned on 9 September 1995. There are several reasons that one could expect the TF coils to survive the higher stresses that develop at higher fields. They were designed to operate at 5.2 Tesla with a vertical field of 0.5 Tesla, whereas the actual vertical field needed for the plasma does not exceed 0.35 Tesla. Their design specification explicitly required they survive some pulses at 6.0 Tesla. TF coil mechanical analysis computer models available during coil design were crude, leading to conservative design. And design analyses also had to consider worst-case misoperations that TFTR`s real time Coil Protection Calculators (CPCs) now positively prevent from occurring.

  4. Neoclassical viscosity effects on resistive magnetohydrodynamic modes in toroidal geometry

    SciTech Connect

    Yang, J.G.; Oh, Y.H.; Choi, D.I. ); Kim, J.Y.; Horton, W. )

    1992-03-01

    The flux-surface-averaged linearized resistive magnetohydrodynamic (MHD) boundary-layer equations including the compressibility, diamagnetic drift, and neoclassical viscosity terms are derived in toroidal geometry. These equations describe the resistive layer dynamics of resistive MHD modes over the collisionality regime between the banana plateau and the Pfirsch--Schlueter. From the resulting equations, the effects of neoclassical viscosity on the stability of the tearing and resistive ballooning modes are investigated numerically. Also, a study is given for the problem of how the neoclassical resistive MHD mode is generated as the collisionality is reduced. It is shown that the neoclassical viscosity terms give a significant destabilizing effect for the tearing and resistive ballooning modes. This destabilization comes mainly from the reduction of the stabilizing effect of the parallel ion sound compression by the ion neoclassical viscosity. In the banana-plateau collisionality limit, where the compressibility is negligible, the dispersion relations of the tearing and resistive ballooning modes reduce to the same form, with the threshold value of the driving force given by {Delta}{sub {ital c}}=0. On the other hand, with the finite neoclassical effect it is found that the neoclassical resistive MHD instability is generated in agreement with previous results. Furthermore, it is shown that this later instability can be generated in a wide range of the collisionality including near the Pfirsch--Schlueter regime as well as the banana-plateau regime, suggesting that this mode is a probable cause of anomalous transport.

  5. A new approach to observe toroidal magnetic fields of magnetars

    NASA Astrophysics Data System (ADS)

    Murakami, H.; Makishima, K.; Enoto, T.; Nakano, T.; Furuta, Y.; Nakazawa, K.

    2016-06-01

    Over the last decade, observational evidence has amounted that magnetars harbor enormous surface dipole magnetic fields (MFs) of B_{d} = 10^{14-15} {G}. Theoretically, we expect even stronger toroidal MFs B_{t} (e.g., Takiwaki+2009), which is observationally supported by a discovery of low-B_{d} magnetars (e.g., SGR 0418+5729; Rea+2013). Here, we will present a new approach to access B_{t} more directly. {Suzaku} allows us to simultaneously observe a soft thermal component and a distinct hard X-ray tail of magnetars. Extensively analyzing two magnetars, 4U 0142+61 and 1E 1547.0-5408, we found that their hard X-ray pulses suffered from slow phase modulations (Makishima+2014, 2015). This can be interpreted as a manifestation of free precession, under an axial deformation by ˜0.01%. If this effect is attributed to the magnetic stress, B_{t}˜10^{16} G is inferred. We further found that, within 6 years observation of 4U 0142+61, the modulation periods remained constant, while the amplitude gradually increased from < 0.4 to ˜1.3 sec. These results suggest the shift of the hard X-ray emission region (or direction).

  6. Analysis of vortical flow with axial swirl and toroidal circulation

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sukalyan

    2006-11-01

    Vortical flows with an axial swirl and a toroidal circulation can be observed in a wide range of fluid mechanical phenomena such as flow around rotary machines or natural vortices like tornadoes and hurricanes. These flows can be described by a general scalar equation if incompressible fluid and negligible viscous dissipation are assumed. We consider one of the simpler cases of this general formulation where the involved equation has a resemblance with the governing equation of the hydrogen problem. As a result, we obtain a quantization relation similar to the expression of quantized energies in an hydrogen atom. We solve the equation for two systems. First, we consider three- dimensional vortices confined between two parallel walls. Our examples include flows between two infinite plates, inside and outside of a vertical cylinder bounded at the ends by walls, and in an axially confined annular region. Then we also use our formulation to compute highly chaotic velocity fields with three-dimensional vortical structures which qualitatively mimic the features of physical flows. Hence, these solutions may be used in modeling of complicated flow systems.

  7. Theory comparison and numerical benchmarking on neoclassical toroidal viscosity torque

    SciTech Connect

    Wang, Zhirui; Park, Jong-Kyu; Logan, Nikolas; Kim, Kimin; Menard, Jonathan E.; Liu, Yueqiang

    2014-04-15

    Systematic comparison and numerical benchmarking have been successfully carried out among three different approaches of neoclassical toroidal viscosity (NTV) theory and the corresponding codes: IPEC-PENT is developed based on the combined NTV theory but without geometric simplifications [Park et al., Phys. Rev. Lett. 102, 065002 (2009)]; MARS-Q includes smoothly connected NTV formula [Shaing et al., Nucl. Fusion 50, 025022 (2010)] based on Shaing's analytic formulation in various collisionality regimes; MARS-K, originally computing the drift kinetic energy, is upgraded to compute the NTV torque based on the equivalence between drift kinetic energy and NTV torque [J.-K. Park, Phys. Plasma 18, 110702 (2011)]. The derivation and numerical results both indicate that the imaginary part of drift kinetic energy computed by MARS-K is equivalent to the NTV torque in IPEC-PENT. In the benchmark of precession resonance between MARS-Q and MARS-K/IPEC-PENT, the agreement and correlation between the connected NTV formula and the combined NTV theory in different collisionality regimes are shown for the first time. Additionally, both IPEC-PENT and MARS-K indicate the importance of the bounce harmonic resonance which can greatly enhance the NTV torque when E×B drift frequency reaches the bounce resonance condition.

  8. Asymmetric radiative damping of low shear toroidal Alfven eigenmodes

    SciTech Connect

    Nyqvist, R. M.; Sharapov, S. E.

    2012-08-15

    Radiative damping of toroidicity-induced Alfven eigenmodes (TAEs) in tokamaks, caused by coupling to the kinetic Alfven wave (KAW), is investigated analytically in the limit of low magnetic shear. A significant asymmetry is found between the radiative damping of the odd TAE, whose frequency lies above the central TAE gap frequency {omega}{sub 0}, and that of the even TAE, with frequency {omega}<{omega}{sub 0}. For the even TAE, which consists of a symmetric combination of neighboring poloidal harmonics (and therefore has ballooning-type mode structure), the coupling results in two non-overlapping, outgoing fluxes of KAWs that propagate radially away from each other and the TAE localization region. In contrast, the odd TAE consists of an antisymmetric combination of neighboring poloidal harmonics, resulting in anti-ballooning mode structure. For this mode, the KAWs initially propagate towards each other and form an interference pattern in the TAE localization region, resulting in a negligibly small escaping flux and a correspondingly low radiative damping rate. As a result of the up/down asymmetry in radiative damping with respect to the mode frequency, the odd TAE may be destabilized by fusion born alpha particles more easily than the usual, even TAE.

  9. Pareto optimal design of sectored toroidal superconducting magnet for SMES

    NASA Astrophysics Data System (ADS)

    Bhunia, Uttam; Saha, Subimal; Chakrabarti, Alok

    2014-10-01

    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.

  10. Control of Compact-Toroid Characteristics by External Copper Shell

    NASA Astrophysics Data System (ADS)

    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.

  11. Spectral Analysis Software for the Compact Toroid Injection Experiment

    NASA Astrophysics Data System (ADS)

    Belknap, Donald

    2009-11-01

    The Compact Toroid Injection Experiment (CTIX) operated by UC Davis functions by producing a spheromak-like plasma which is accelerated via a coaxial railgun. In order to examine features of the plasma such as impurities and temperature, the spectrum of the plasma is measured during a shot. Because of the number of shots that may be taken in a single day, a computer analysis program is an expedient method of analyzing the spectra. A graphic user interface (GUI) was designed to allow the user to easily read the spectral images from an archived data file and interactively perform functions such as CCD camera tilt correction, background subtraction, and wavelength calibration. The code for the GUI, background subtraction, wavelength calibration, and tilt correction algorithms are written in a high-level programming language, Igor, to allow for easy extension by CTIX scientists. The code can be extended to add features that can perform analysis on large numbers of spectra. Results of CTIX shots and calibration spectra will be presented.

  12. A new approach to observe toroidal magnetic fields of magnetars

    NASA Astrophysics Data System (ADS)

    Murakami, H.; Makishima, K.; Enoto, T.; Nakano, T.; Furuta, Y.; Nakazawa, K.

    2016-06-01

    Over the last decade, observational evidence has amounted that magnetars harbor enormous surface dipole magnetic fields (MFs) of B_{d} = 10^{14-15} {G}. Theoretically, we expect even stronger toroidal MFs B_{t} (e.g., Takiwaki+2009), which is observationally supported by a discovery of low-B_{d} magnetars (e.g., SGR 0418+5729; Rea+2013). Here, we will present a new approach to access B_{t} more directly. Suzaku allows us to simultaneously observe a soft thermal component and a distinct hard X-ray tail of magnetars. Extensively analyzing two magnetars, 4U 0142+61 and 1E 1547.0-5408, we found that their hard X-ray pulses suffered from slow phase modulations (Makishima+2014, 2015). This can be interpreted as a manifestation of free precession, under an axial deformation by ˜0.01%. If this effect is attributed to the magnetic stress, B_{t}˜10^{16} G is inferred. We further found that, within 6 years observation of 4U 0142+61, the modulation periods remained constant, while the amplitude gradually increased from < 0.4 to ˜1.3 sec. These results suggest the shift of the hard X-ray emission region (or direction).

  13. A Simple Sperm DNA Toroid Integrity Test and Risk of Miscarriage

    PubMed Central

    Chan, Philip J.; Orzylowska, Eliza M.; Corselli, Johannah U.; Jacobson, John D.; Wei, Albert K.

    2015-01-01

    Current methods of analyzing sperm chromatin competency overlook the inner sperm compartment which is inaccessible to probes and reagents. By breaking the molecular protamine disulfide bridges, the DNA toroids are exposed to integrity analysis. The aim was to develop a simple nuclear toroid test and determine its association with fertilization, pregnancy, and miscarriage. The approach involved treating washed sperm remaining after ICSI procedures (N = 35 cases) with acidified Triton X-100 and dithiothreitol (DTT) before Diff-Quik staining. Percentages of sperm with normal chromatin indicated by light-colored nuclei were assessed. The toroid integrity test showed more sperm with normal chromatin in the pregnant group (73.6 ± 1.7%, mean ± SEM) when compared with the miscarriage (51.2 ± 6.6%) or nonpregnant groups (60.9 ± 4.8%). Furthermore, the toroid results were correlated with ICSI fertilization (R = 0.32, P = 0.04) and pregnancy outcome (pregnant cases 73.6 ± 1.7% versus nonpregnant 58.0 ± 3.9%, P = 0.001). ROC calculated cut-off was >70.0% for normal toroid integrity (sensitivity 0.98, specificity 0.33, and diagnostic accuracy 78.3%). An association between normal sperm toroid integrity and miscarriage was evident when the staining procedure included acidified detergent DTT pretreatment. PMID:25649376

  14. Zonal Toroidal Harmonic Expansions of External Gravitational Fields for Ring-like Objects

    NASA Astrophysics Data System (ADS)

    Fukushima, Toshio

    2016-08-01

    We present an expression of the external gravitational field of a general ring-like object with axial and plane symmetries such as oval toroids or annular disks with an arbitrary density distribution. The main term is the gravitational field of a uniform, infinitely thin ring representing the limit of zero radial width and zero vertical height of the object. The additional term is derived from a zonal toroidal harmonic expansion of a general solution of Laplace’s equation outside the Brillouin toroid of the object. The special functions required are the point value and the first-order derivative of the zonal toroidal harmonics of the first kind, namely, the Legendre function of the first kind of half integer degree and an argument that is not less than unity. We developed a recursive method to compute them from two pairs of seed values explicitly expressed by some complete elliptic integrals. Numerical experiments show that appropriately truncated expansions converge rapidly outside the Brillouin toroid. The truncated expansion can be evaluated so efficiently that, for an oval toroid with an exponentially damping density profile, it is 3000–10,000 times faster than the two-dimensional numerical quadrature. A group of the Fortran 90 programs required in the new method and their sample outputs are available electronically.

  15. Effectiveness of Disruption Mitigation and Toroidal Asymmetry with Two Gas Jets

    NASA Astrophysics Data System (ADS)

    Granetz, R. S.; Olynyk, G. M.; Reinke, M. L.; Whyte, D. G.; Coombs, S.; Sugihara, M.

    2011-10-01

    Alcator C-Mod has done extensive disruption mitigation studies in the past using a high-pressure gas jet at a single toroidal location. Measurements with a pair of AXUV diode arrays (de facto solid-state bolometers) show that there can be a large toroidal asymmetry of the radiated power during mitigated disruptions. This is problematic for the ITER first wall, so ITER is planning to use multiple gas jets at a number of toroidal locations to reduce the asymmetric wall loading. To test the effectiveness of this concept, a 2nd gas jet is being added to Alcator C-Mod at a location around the torus from the existing jet. In addition, a toroidally distributed set of 5 AXUV diodes is being installed to provide enhanced toroidal resolution of radiated power. Experiments to measure the effect on toroidal asymmetry with the two gas jets will be performed early in the next campaign (fall 2011). Additional studies of other issues with two gas jets, such as mitigation of halo currrents and thermal loads, non-synchronous timing, different gas combinations, etc are also being planned. Supported by US DoE award DE-FC02-99ER54512.

  16. Material Procurement Report for the FNAL pp Forward Detector's Toroids and Cos8 Dipole Magnets

    SciTech Connect

    Cline, D.; Morse, R.; Orosz, I.; Thomas, L.C.

    1980-10-27

    We outline the possibilities of starting construction of the {bar p}p forward detector toroids and cos{theta} dipole magnets described in CDP Note 64 as soon as possible using material that already exists on the FNAL site. Personal inspection of the steel supplies indicates that as much as 2000 tons of steel or over 50% of all the steel needed for the toroids is now available at the FNAL boneyard. Copper inventories indicate that there is enough copper on the FNAL site to construct both the toroid magnets and the cos{theta} dipole magnets. A construction schedule of one toroid in FY81, two toroids in FY82, and the final toroid in FY83 is shown to be feasible. Floor space and loading requirements for the IR Hall housing the forward detector are examined and finally, budgets for the initial FY8l phase and the completed project are given. The FY81 costs are $393K and to-completion costs are $1506K.

  17. Analyses of core heat transport in plasmas with different toroidal rotation profiles in JT-60U

    NASA Astrophysics Data System (ADS)

    Narita, Emi; Honda, Mitsuru; Hayashi, Nobuhiko; Urano, Hajime; Ide, Shunsuke; Fukuda, Takeshi

    2013-10-01

    It has been reported that in H-mode plasmas, toroidal rotation in the co direction with respect to the plasma current is more favorable for energy confinement than that in the counter direction. Effects of toroidal rotation on core temperature profiles have been pointed out, whereas the improved confinement has been found to be due to an increase in the pedestal temperature with co-toroidal rotation and profile resilience. In JT-60U, roles of toroidal rotation have been studied using neutral beam injection changes. In this study, core heat transport of these plasmas with different toroidal rotation profiles is investigated with several transport models implemented in the transport code TOPICS. These transport models give the anomalous heat diffusivity and are tested against conventional H-mode plasmas in JT-60U. The calculations are performed with the E × B shear effect. The relationship between heat transport and toroidal rotation is examined with a flux-tube gyrokinetic code, which we will present in the paper. Work supported by JSPS Research Fellowships for Young Scientists.

  18. Fabrication of large radii toroidal surfaces by single point diamond turning

    SciTech Connect

    Cunningham, J.P.; Marlar, T.A.; Miller, A.C.

    1995-12-31

    An unconventional machining technique has been developed for producing relatively large radii quasi-toroidal surfaces which could not normally be produced by conventional diamond turning technology. The maximum radial swing capacity of a diamond turning lathe is the limiting factor for the rotational radius of any toroid. A typical diamond turned toroidal surface is produced when a part is rotated about the spindle axis while the diamond tool contours the surface with any curved path. Toric surfaces sliced horizontally, have been used in laser resonator cavities. This paper will address the fabrication of a special case of toroids where a rotating tool path is a circle whose center is offset from the rotational axis of the toroid by a distance greater than the minor radius of the tool path. The quasi-toroidal surfaces produced by this technique approximate all asymmetrical combinations of concave/convex sections of a torus. Other machine configurations have been reported which offer alternative approaches to the fabrication of concave asymmetric aspheric surfaces.

  19. ITER tokamak device

    NASA Astrophysics Data System (ADS)

    Doggett, J.; Salpietro, E.; Shatalov, G.

    1991-07-01

    The results of the Conceptual Design Activities for the International Thermonuclear Experimental Reactor (ITER) are summarized. These activities, carried out between April 1988 and December 1990, produced a consistent set of technical characteristics and preliminary plans for co-ordinated research and development support of ITER, a conceptual design, a description of design requirements and a preliminary construction schedule and cost estimate. After a description of the design basis, an overview is given of the tokamak device, its auxiliary systems, facility and maintenance. The interrelation and integration of the various subsystems that form the ITER tokamak concept are discussed. The 16 ITER equatorial port allocations, used for nuclear testing, diagnostics, fueling, maintenance, and heating and current drive, are given, as well as a layout of the reactor building. Finally, brief descriptions are given of the major ITER sub-systems, i.e., (1) magnet systems (toroidal and poloidal field coils and cryogenic systems), (2) containment structures (vacuum and cryostat vessels, machine gravity supports, attaching locks, passive loops and active coils), (3) first wall, (4) divertor plate (design and materials, performance and lifetime, a.o.), (5) blanket/shield system, (6) maintenance equipment, (7) current drive and heating, (8) fuel cycle system, and (9) diagnostics.

  20. Thermal and electrical joint test for the helical field coils in the Advanced Toroidal Facility

    SciTech Connect

    Brown, R.L.; Johnson, R.L.

    1985-01-01

    Initial feasibility studies of a number of configurations for the Advanced Toroidal Facility (ATF) resulted in the selection of a resistive copper continuous-coil torsatron as the optimum device considering the physics program, cost, and schedule. Further conceptual design work was directed toward optimization of this configuration and, if possible, a shorter schedule. It soon became obvious that in order to shorten the schedule, a number of design and fabrication activities should proceed in parallel. This was most critical for the vacuum vessel and the helical field (HF) coils. If the HF coils were wound in place on a completed vacuum vessel, the overall schedule would be significantly (greater than or equal to12 months) longer. The approach of parallel scheduel paths requires that the HF coils be segmented into parts of less than or equal to180 of poloidal angle and that joints be made on a turn-by-turn basis when the segments are installed. It was obvious from the outset that the compact and complex geometry of the joint design presented a special challenge in the areas of reliability, assembly, maintenance, disassembly, and cost. Also, electrical, thermal, and force excursions are significant for these joints. A number of soldered, welded, brazed, electroplated, and bolted joints were evaluated. The evaluations examined fabrication feasibility and complexity, thermal-electrical performance at approximately two-thirds of the steady-state design conditions, and installation and assembly processes. Results of the thermal-electrical tests were analyzed and extrapolated to predict performance at peak design parameters. The final selection was a lap-type joint clamped with insulated bolts that pass through the winding packing. 3 refs., 4 figs.

  1. Installation of a Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment

    NASA Astrophysics Data System (ADS)

    Traverso, P. J.; Maurer, D. A.; Ennis, D. A.; Hartwell, G. J.; Cianciosa, M. R.

    2015-11-01

    A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The initial system takes a single point measurement on the magnetic axis and will be used to assess options for an expansion to a multi-point system to enable better 3D equilibrium reconstructions using the V3FIT code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YaG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. The beam line is designed to propagate ~ 8 m to the mid-plane of the CTH device with the beam diameter < 3 mm inside the plasma volume. An Andor iStar DH740-18U-C3 image intensified CCD camera is used in conjunction with a Holospec f/1.8 spectrograph to collect the red-shifted scattered light from 532-580 nm. A single point system will initially measure plasmas with core electron temperatures of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

  2. Effects of edge-localized mode-induced neoclassical toroidal viscosity torque on the toroidal intrinsic rotation in the EAST tokamak

    NASA Astrophysics Data System (ADS)

    Xiong, H.; Xu, G. S.; Sun, Y.; Wan, B. N.; Yan, N.; Wang, H. Q.; Wang, F. D.; Naulin, V.

    2013-12-01

    Intrinsic rotation has been observed in lower hybrid current-driven (LHCD) H-mode plasmas with type-III edge-localized modes (ELMs) on Experimental Advanced Superconducting Tokamak (EAST), and it is found that the edge toroidal rotation accelerated before the onset of the ELM burst. Magnetic perturbation analysis shows there is a perturbation amplitude growth below 30 kHz corresponding to the edge rotation acceleration. Using the filament model, the neoclassical toroidal viscosity (NTV) code shows there is a co-current NTV torque at the edge, which may be responsible for the edge rotation acceleration. For maximum displacement ∼1 cm and toroidal mode number n=15, the calculated torque density is ∼0.44 N/m2, comparable with the average edge toroidal angular momentum change rate ∼1.24 N/m2. Here, the 1 cm maximum magnetic surface displacement estimated from the experimental observation corresponds to a maximum magnetic perturbation ∼ 10-3-10-2 T, in accordance with magnetic perturbation measurements during ELMs. By varying n from 10 to 20, the magnitude of the edge NTV torque density is mainly ∼0.1-1 N/m2. This significant co-current torque indicates that the NTV theory may be important in rotation problems during ELMs in H-mode plasmas. To better illuminate the problem, magnetic surface deformation obtained from other codes is desired for a more accurate calculation.

  3. Toroidal Single Wall Carbon Nanotubes in Fullerene Crop Circles

    NASA Technical Reports Server (NTRS)

    Han, Jie; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We investigate energetics and structure of circular and polygonal single wall carbon nanotubes (SWNTs) using large scale molecular simulations on NAS SP2, motivated by their unusual electronic and magnetic properties. The circular tori are formed by bending tube (no net whereas the polygonal tori are constructed by turning the joint of two tubes of (n, n), (n+1, n-1) and (n+2, n-2) with topological pentagon-heptagon defect, in which n =5, 8 and 10. The strain energy of circular tori relative to straight tube decreases by I/D(sup 2) where D is torus diameter. As D increases, these tori change from buckling to an energetically stable state. The stable tori are perfect circular in both toroidal and tubular geometry with strain less than 0. 03 eV/atom when D greater than 10, 20 and 40 nm for torus (5,5), (8,8) and (10, 10). Polygonal tori, whose strain is proportional to the number of defects and I/D are energetically stable even for D less than 10 nm. However, their strain is higher than that of perfect circular tori. In addition, the local maximum strain of polygonal tori is much higher than that of perfect circular tori. It is approx. 0.03 eV/atom or less for perfect circular torus (5,5), but 0.13 and 0.21 eV/atom for polygonal tori (6,4)/(5,5) and (7,3)/(5,5). Therefore, we conclude that the circular tori with no topological defects are more energetically stable and kinetically accessible than the polygonal tori containing the pentagon-heptagon defects for the laser-grown SWNTs and Fullerene crop circles.

  4. Progress on Thomson scattering in the Pegasus Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Schlossberg, D. J.; Bongard, M. W.; Fonck, R. J.; Schoenbeck, N. L.; Winz, G. R.

    2013-11-01

    A novel Thomson scattering system has been implemented on the Pegasus Toroidal Experiment where typical densities of 1019 m-3 and electron temperatures of 10 to 500 eV are expected. The system leverages technological advances in high-energy pulsed lasers, volume phase holographic (VPH) diffraction gratings, and gated image intensified (ICCD) cameras to provide a relatively low-maintenance, economical, robust diagnostic system. Scattering is induced by a frequency-doubled, Q-switched Nd:YAG laser (2 J at 532 nm, 7 ns FWHM pulse) directed to the plasma over a 7.7 m long beam path, and focused to < 3 mm throughout the collection region. Inter-shot beam alignment is adjustable with less than a 0.01 mm spatial resolution in the collection region. A custom lens system collects scattered photons at radii 15 cm to 85 cm from the machine's center, at ~ F/6 with 14 mm radial resolution. The initial configuration provides scattering measurements at 12 spatial locations and 12 simultaneous background measurements at adjacent locations. If plasma background subtraction proves to be insignificant, these background channels will be used as viewing channels. Each spectrometer supports 8 spatial channels and can provide 8 or more spectral bins each. The spectrometers use high-efficiency VPH transmission gratings (eff. > 80%) and fast-gated ICCDs (gate > 2 ns, Gen III intensifier) with high-throughput (F/1.8), achromatic lensing. A stray light mitigation facility has been implemented, consisting of a multi-aperture optical baffle system and a simple beam dump. Successful stray light reduction has enabled detection of scattered signal, and Rayleigh scattering has been used to provide a relative calibration. Initial temperature measurements have been made and data analysis algorithms are under development.

  5. Fast-Ion Physics in Burning Toroidal Plasmas

    NASA Astrophysics Data System (ADS)

    Heidbrink, W. W.

    2001-10-01

    What are the key scientific issues for energetic-particle physics in magnetically confined plasma? Which of these issues can be effectively addressed in a burning tokamak experiment? Single-particle effects are well understood and provide a firm basis for extrapolation to a burning plasma. Effects in this category include the production of alpha particles, their deceleration due to classical Coulomb scattering, particle losses in the static magnetic field structure, and turbulent transport caused by fluctuations of the background plasma. In contrast, collective effects involving fast ions are more poorly understood and extrapolations are unreliable. Collective modes of concern include toroidicity-induced and ellipticity-induced Alfvén eigenmodes (TAE and EAE), kinetic ballooning modes, and internal kink modes. When weakly damped by the background plasma, the stability of these modes can be altered by the alpha-particle population. In some projections to burning experiments, a ``sea'' of TAEs are unstable. The nonlinear saturation and consequent fast-ion transport of many, closely-spaced, modes is expected to differ from existing experiments, where fewer modes are typically excited. In high-temperature burning plasmas (T ~20 keV), the alpha-particle pressure is comparable to the background plasma pressure. In this ``energetic-particle mode'' regime, the MHD normal modes are modified and frequency chirping and other complicated phenomena are observed. Another issue is the possibility of exploiting instabilities such as compressional Alfvén eigenmodes to transfer energy from alpha particles to thermal ions without heating electrons. >From the standpoint of energetic-particle physics, the ideal burning plasma experiment is well diagnosed and can vary the alpha pressure to span both stable and unstable operating regimes.

  6. Transport bifurcation induced by sheared toroidal flow in tokamak plasmas

    SciTech Connect

    Highcock, E. G.; Barnes, M.; Roach, C. M.; Cowley, S. C.

    2011-10-15

    First-principles numerical simulations are used to describe a transport bifurcation in a differentially rotating tokamak plasma. Such a bifurcation is more probable in a region of zero magnetic shear than one of finite magnetic shear, because in the former case the component of the sheared toroidal flow that is perpendicular to the magnetic field has the strongest suppressing effect on the turbulence. In the zero-magnetic-shear regime, there are no growing linear eigenmodes at any finite value of flow shear. However, subcritical turbulence can be sustained, owing to the existence of modes, driven by the ion temperature gradient and the parallel velocity gradient, which grow transiently. Nonetheless, in a parameter space containing a wide range of temperature gradients and velocity shears, there is a sizeable window where all turbulence is suppressed. Combined with the relatively low transport of momentum by collisional (neoclassical) mechanisms, this produces the conditions for a bifurcation from low to high temperature and velocity gradients. A parametric model is constructed which accurately describes the combined effect of the temperature gradient and the flow gradient over a wide range of their values. Using this parametric model, it is shown that in the reduced-transport state, heat is transported almost neoclassically, while momentum transport is dominated by subcritical parallel-velocity-gradient-driven turbulence. It is further shown that for any given input of torque, there is an optimum input of heat which maximises the temperature gradient. The parametric model describes both the behaviour of the subcritical turbulence (which cannot be modelled by the quasi-linear methods used in current transport codes) and the complicated effect of the flow shear on the transport stiffness. It may prove useful for transport modelling of tokamaks with sheared flows.

  7. Fabrication of large radii toroidal surfaces by single point diamond turning

    SciTech Connect

    Cunningham, J.P.; Marlar, T.A.; Miller, A.C.; Paterson, R. L.

    1995-12-31

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

  8. Evidence of Neoclassical Toroidal Viscosity on the Neoclassical Tearing Modes in TCV tokamak

    NASA Astrophysics Data System (ADS)

    Nowak, S.; Lazzaro, E.; Sauter, O.; Canal, G.; Duval, B.; Federspiel, L.; Karpushov, A. N.; Kim, D.; Reimerdes, H.; Rossel, J.; Wagner, D.; the Tcv Team

    2012-12-01

    The interplay between the plasma toroidal rotation and the onset of magnetohydrodynamics instabilities, such as the Neoclassical Tearing Modes (NTMs), is an important issue for tokamak performance. An interesting mechanism characterizing this interaction is the breaking of axisymmetry due to the NTM helical structure, which is the source of a magnetic viscous drag parallel to the toroidal field. This effect, known as Neoclassical Toroidal Viscosity (NTV) depends on magnetic island width, and is responsible of the nearly global slowing down of the toroidal velocity across the profile. In the TCV tokamak the spontaneous plasma toroidal rotation profile, observed even in absence of other external momentum sources [1], can be modified by nearly central electron cyclotron heating (ECH) with a slight poloidal asymmetry and current drive (ECCD) [1,2,3]. The evidence of NTV effect on the plasma toroidal velocity profile of TCV is apparent as a pronounced flattening at the onset of m/n=3/2 and 2/1 tearing instabilities in the neoclassical regime in TCV discharges (Ip~150 kA, ne_av~2 1019 m-3 Te~3 keV) with 1.5 MW EC ramp up/down phases. Comparison of the measured and calculated toroidal plasma velocity is performed using the NTV formulation [4,5] applicable in the collisionless regimes. The different aspects of the NTM onset associated both with the ECH-coECCD effect on the current profile and with NTV observed in several TCV discharges are discussed, in the frame of classical and neoclassical tearing modes theory applied to 3/2 and 2/1 modes.

  9. Device for plasma confinement and heating by high currents and nonclassical plasma transport properties

    DOEpatents

    Coppi, B.; Montgomery, D.B.

    1973-12-11

    A toroidal plasma containment device having means for inducing high total plasma currents and current densities and at the same time emhanced plasma heating, strong magnetic confinement, high energy density containment, magnetic modulation, microwaveinduced heating, and diagnostic accessibility is described. (Official Gazette)

  10. Photovoltaic device

    DOEpatents

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-06-02

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device with a multilayered photovoltaic cell assembly and a body portion joined at an interface region and including an intermediate layer, at least one interconnecting structural member, relieving feature, unique component geometry, or any combination thereof.

  11. Photovoltaic device

    SciTech Connect

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-09-01

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device (10) with a multilayered photovoltaic cell assembly (100) and a body portion (200) joined at an interface region (410) and including an intermediate layer (500), at least one interconnecting structural member (1500), relieving feature (2500), unique component geometry, or any combination thereof.

  12. Nonlinear stability of field-reversed configurations with self-generated toroidal field

    SciTech Connect

    Omelchenko, Y. A.; Schaffer, M. J.; Parks, P. B.

    2001-10-01

    The field-reversed configuration (FRC) is a high-beta compact toroidal plasma confinement scheme in which the external poloidal field is reversed on the geometric axis by azimuthal (toroidal) plasma current. A quasineutral, hybrid, particle-in-cell (PIC) approach [Y. A. Omelchenko and R. N. Sudan, Phys. Plasmas 2, 2773 (1995)] is applied to study long-term nonlinear stability of computational FRC equilibria to a number of toroidal modes, including the most disruptive tilt mode. In particular, a self-generated toroidal magnetic field is found to be an important factor in mitigating the instability and preventing the confinement disruption. This is shown to be a unique FRC property resulting from the Hall effect in the regions of vanishing poloidal magnetic field. The instability-driven toroidal field stabilizes kink formation by increasing the magnetic field energy without destabilizing curvature-driven plasma motion. Finally, the tilt instability saturates due to nonlinear, finite Larmor radius (FLR) effects and plasma relaxation to a quasisteady kinetic state. During this transition the FRC is shown to dissipate a substantial amount of initially trapped flux and plasma energy. These effects are demonstrated for kinetic and fluid-like, spherical and prolate FRCs.

  13. Large and Tunable Polar-Toroidal Coupling in Ferroelectric Composite Nanowires toward Superior Electromechanical Responses

    PubMed Central

    Chen, W. J.; Zheng, Yue; Wang, Biao

    2015-01-01

    The collective dipole behaviors in (BaTiO3)m/(SrTiO3)n composite nanowires are investigated based on the first-principles-derived simulations. It demonstrates that such nanowire systems exhibit intriguing dipole orders, due to the combining effect of the anisotropic electrostatic interaction of the nanowire, the SrTiO3-layer-modified electrostatic interaction and the multiphase ground state of BaTiO3 layer. Particularly, a strong polar-toroidal coupling that is tunable by the SrTiO3-layer thickness, temperature, external strains and electric fields is found to exist in the nanowires, with the appearance of fruitful dipole states (including those being purely polar, purely toroidal, both polar and toroidal, or distorted toroidal) and phase boundaries. As a consequence, an efficient cross control of the toroidal (polar) order by static (curled) electric field, and superior piezoelectric and piezotoroidal responses, can be achieved in the nanowires. The result provides new insights into the collective dipole behaviors in nanowire systems. PMID:26100094

  14. Instability of Non-uniform Toroidal Magnetic Fields in Accretion Disks

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Kota; Hoshino, Masahiro

    2016-05-01

    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.

  15. Simulation Study of Toroidal Flow Generation of Minority Ions by Local ICRF Heating

    NASA Astrophysics Data System (ADS)

    Murakami, Sadayoshi; Itoh, Kimitaka; Zheng, Linjin; Van Dam, James W.; Fukuyama, Atsushi

    2015-12-01

    The toroidal flow generation of minority ions by the local ion cyclotron range of frequencies (ICRF) heating is investigated in a tokamak plasma by applying the GNET code, which can solve the drift kinetic equation in the 5-D phase space. An asymmetry of velocity distribution function in the parallel direction is found and two types of toroidal averaged flow of minority ions are observed. One is the sheared flow near the RF power absorption region depending on the sign of k||, and the other is the toroidal flow, which is larger than the previous one, independent of the sign of k||. It is found that the k||-sign-independent toroidal flow is generated by the net toroidal motion of energetic tail ions and that the k||-sign-dependent flow is related to the mechanism proposed by Ohkawa [Phys. Plasmas 12, 094506 (2005)].

  16. Formation of field-reversed configuration by use of two merging spheromaks with opposing toroidal field

    NASA Astrophysics Data System (ADS)

    Ono, Yasushi

    2016-03-01

    In 1986, we, U. Tokyo group first reported the new formation of the field-reversed configuration (FRC) by two merging spheromaks with opposing toroidal field. This unique formation has been developed mainly in our TS-3 and TS- 4 merging experiments, leading us to a new scenario of FRC slow-formation, heating and current-amplification. Its formation efficiency is much higher than the conventional field-reversed theta-pinch method. The relaxation from the force-free (β˜0.05-0.1) spheromaks to the high-β (β˜0.7-1) FRC is caused by conversion of the toroidal (partly poloidal) magnetic energy of the spheromaks to the ion thermal energy of the FRC through the reconnection outflow. The reconnection heating energy scales with square of the reconnecting magnetic field, suggesting direct access to the alpha heating without using any additional heating. A central solenoid (CS) coil was installed successfully to amplify the FRC plasma current by factor 2. Our toroidal mode observations suggest that the tilting stability of the oblate FRC is provided by ion kinetic effect. As another important extension, fast application of external toroidal magnetic field transformed this oblate FRC into an ultra-high-β spherical tokamak (ST) with diamagnetic toroidal magnetic field, suggesting close relationship between FRCs and high-β STs in the second stable region for ballooning mode.

  17. Imaging extreme ultraviolet spectrometer employing a single toroidal diffraction grating: the initial evaluation.

    PubMed

    Huber, M C; Timothy, J G; Morgan, J S; Lemaitre, G; Tondello, G; Jannitti, E; Scarin, P

    1988-08-15

    A high-efficiency extreme ultraviolet (EUV) imaging spectrometer has been constructed and tested. The spectrometer employs a concave toroidal grating illuminated at normal incidence in a Rowland circle mounting and has only one reflecting surface. The toroidal grating has been fabricated by a new technique employing an elastically deformable submaster grating which is replicated in a spherical form and then mechanically distorted to produce the desired aspect ratio of the toroidal surface for stigmatic imaging over the selected wavelength range. The fixed toroidal grating used in the spectrometer is then replicated from this surface. Photographic tests and initial photoelectric tests with a 2-D pulse-counting detector system have verified the image quality of the toroidal grating at wavelengths near 600 A. The results of these initial tests are described in detail, and the basic designs of two instruments which could employ the imaging spectrometer for astrophysical investigations in space are briefly described, namely, a high-resolution EUV spectroheliometer for studies of the solar chromosphere, transition region, and corona and an EUV spectroscopic telescope for studies of nonsolar objects. PMID:20539406

  18. Passing particle toroidal precession induced by electric field in a tokamak

    SciTech Connect

    Andreev, V. V.; Ilgisonis, V. I.; Sorokina, E. A.; NRC “Kurchatov Institute”, Kurchatov Sq. 1, Moscow 123182

    2013-12-15

    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.

  19. Correlation of electrostatic fluctuation and reversal of toroidal field in the reversed-field pinch plasma

    SciTech Connect

    Yambe, Kiyoyuki; Koguchi, Haruhisa; Sakakita, Hajime; Hirano, Yoichi; Kiyama, Satoru

    2011-06-15

    The magnetic fluctuations and electrostatic probe potential have been measured in the Toroidal Pinch Experiment - RX (TPE-RX) reversed-field pinch plasma [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)] (at the plasma surface r/a = 1.00). Fast electrons with energy comparable to or slightly higher than the core electron temperature are observed as many spikes in the electrostatic probe signal. These electrons are diffused by a fluctuating magnetic field from the core region. During the period of mild deepening of the reversal of the edge toroidal field, a significant reduction in the spike signal, increases in electron density and soft x-ray radiation, and a decrease in the D{alpha} line radiation are observed, even though the reduction in magnetic fluctuations is not significant during the same period, which indicates that the mild deepening of the reversal of the toroidal field can improve the confinement of fast electrons.

  20. Low-loss metamaterial electromagnetically induced transparency based on electric toroidal dipolar response

    SciTech Connect

    Li, Hai-ming; Liu, Shao-bin Liu, Si-yuan; Ding, Guo-wen; Yang, Hua; Yu, Zhi-yang; Zhang, Hai-feng; Wang, Shen-yun

    2015-02-23

    In this paper, a low-loss and high transmission analogy of electromagnetically induced transparency based on electric toroidal dipolar response is numerically and experimentally demonstrated. It is obtained by the excitation of the low-loss electric toroidal dipolar response, which confines the magnetic field inside a dielectric substrate with toroidal geometry. The metamaterial electromagnetically induced transparency (EIT) structure is composed of the cut wire and asymmetric split-ring resonators. The transmission level is as high as 0.88, and the radiation loss is greatly suppressed, which can be proved by the surface currents distributions, the magnetic field distributions, and the imaginary parts of the effective permeability and permittivity. It offers an effective way to produce low-loss and high transmission metamaterial EIT.

  1. Internal rotation and toroidal part of the magnetic field of AB Doradus

    NASA Astrophysics Data System (ADS)

    Hiremath, K. M.

    2000-06-01

    We solve analytically Chandrasekhar's (1956) MHD equations for the steady parts of internal rotation and toroidal component of the magnetic field of the AB Doradus. By taking observed (Donati and Cameron 1997) surface rotation as the boundary condition and assuming that the base of the convection zone rotates rigidly, we estimate the size of the convective envelope to be 40% of the radius and the rotation velocity at the base to be not less than 1.42 x 10-4 rad/sec. We deduce that the toroidal magnetic field is distributed throughout the convective envelope. By taking the average density of 1.78gm cm-3 and radius 5.95 x 1010 cms (Allen 1972), we obtain a Mega gauss field near base of the convective envelope. We present rotational and toroidal magnetic field profiles in the interior, and conjecture on the time dependent part of the magnetic field.

  2. Observations of toroidicity-induced Alfven eigenmodes in a reversed field pinch plasma

    SciTech Connect

    Regnoli, G.; Bergsaaker, H.; Tennfors, E.; Zonca, F.; Martines, E.; Serianni, G.; Spolaore, M.; Vianello, N.; Cecconello, M.; Antoni, V.; Cavazzana, R.; Malmberg, J.-A.

    2005-04-15

    High frequency peaks in the spectra of magnetic field signals have been detected at the edge of Extrap-T2R [P. R. Brunsell, H. Bergsaaker, M. Cecconello, J. R. Drake, R. M. Gravestijn, A. Hedqvist, and J.-A. Malmberg, Plasma Phys. Controlled Fusion, 43, 1457 (2001)]. The measured fluctuation is found to be mainly polarized along the toroidal direction, with high toroidal periodicity n and Alfvenic scaling (f{proportional_to}B/{radical}(m{sub i}n{sub i})). Calculations for a reversed field pinch plasma predict the existence of an edge resonant, high frequency, high-n number toroidicity-induced Alfven eigenmode with the observed frequency scaling. In addition, gas puffing experiments show that edge density fluctuations are responsible for the rapid changes of mode frequency. Finally a coupling with the electron drift turbulence is proposed as drive mechanism for the eigenmode.

  3. The steady state toroidal magnetic field at the core-mantle boundary

    NASA Technical Reports Server (NTRS)

    Pearce, S. J.; Levy, E. H.

    1987-01-01

    Recent measurements indicate that the strength of the toroidal magnetic field at Earth's core-mantle boundary is comparable in strength to the poloidal field - 5 to 10 gauss. Calculations are given to show that this is an inevitable result of the external boundary condition on the core, in which the mantle electrical conductivity is several orders of magnitude lower than that of the core. The measurements are shown to imply that the internal core magnetic field is in the range of several hundred gauss. Thus the measurements imply that the Earth's core contains a strong toroidal magnetic field. They also support the idea that Earth's dynamo, and by implication, other planetary magnetic fields, involves efficient toroidal magnetic field generation through strong differential rotation.

  4. Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks

    SciTech Connect

    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.

  5. Experimental Investigation of the Natural Frequencies of Liquids in Toroidal Tanks

    NASA Technical Reports Server (NTRS)

    McCarty, John Locke; Leonard, H. Wayne; Walton, William C., Jr.

    1960-01-01

    Several toroidal configurations applicable to missile and space-vehicle liquid storage systems were oscillated to study the natural frequencies of the antisymmetric modes of contained liquids over a range of liquid depths and tank sizes. Natural frequencies for tank oscillations parallel to the free surface of both vertical and horizontal tank orientations. Natural frequencies were obtained. The data are presented in terms of dimensionless parameters which are obtained by relating experimentally determined natural liquid frequencies to analytical expressions developed through consideration of the physics of the problem and from existing solutions for liquids in tanks having similar boundaries at the liquid surface. The experimental results obtained for the toroids indicate that these parameters are applicable to the prediction of the natural frequencies of fluids in toroids of general geometry and size.

  6. Joint Instability of Differential Rotation and Toroidal Magnetic Fields below the Solar Convection Zone, II

    NASA Astrophysics Data System (ADS)

    Gilman, P. A.; Fox, P.

    1997-05-01

    At the 1996 AAS/SPD meeting in Madison we reported first results for the joint instability of differential rotation and toroidal magnetic fields to 2D disturbances (see also Gilman and Fox, Paper I, July 20 1997 issue of ApJ). This analysis was for the toroidal field profile B=a*sin(LAT)cos(LAT). This paper reports results for the profile B=(a*sin(LAT)+b*(sin(LAT))(3) ))cos(LAT), which, with b<-a<0, allows for a node in the toroidal field at latitude arcsin (-a/b). This generalization is of interest because we should expect such a node to appear and migrate equatorward as the sun proceeds from one sunspot cycle to the next. As with the simpler profile, instability occurs for virtually all differential rotation amplitudes, and all toroidal field amplitudes and shapes, and remains confined to disturbances with longitudinal wave number m=1. For a, b>0, the instability is enhanced for the same a compared to the b=0 case, particularly in high latitudes. For 0>b>-a (so no node is present) the instability is similar to the b=0 case but with diminished growth rates, due to the reduction of toroidal fields at high latitudes. At b=-a, the symmetric mode of instability vanishes, but the antisymmetric mode remains. For b<-a<0, both symmetric and antisymmetric modes are unstable, but with disturbances confined largely to the domain poleward of the node, unless the toroidal field energy greatly exceeds the kinetic energy of differential rotation. Unstable disturbances spread and migrate toward the equator as the field strength is increased and as the node is moved equatorward. Thus, the instability may still contribute to the existence of the solar butterfly diagram, and to other solar dynamo presses.

  7. Direct Electron Heating at Moderate Harmonic Number for Compact Ignition Devices

    SciTech Connect

    R. Majeski

    1999-07-01

    Direct electron heating of compact ignition devices by radio-frequency power in the 300-400 MHz,range is discussed. The possible advantage of this approach to heating an ignition device, as opposed to resonant heating of an ion population, is the insensitivity to the exact value of the magnitude field. Heating with central power deposition during a toroidal field ramp is therefore possible.

  8. A feasibility study of developing toroidal tanks for a spinning spacecraft. Part 2: Evaluation of fluid behavior in spinning toroidal tanks

    NASA Technical Reports Server (NTRS)

    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.

  9. Characterisation of the Interaction between Toroidal Vortex Structures and Flame Front Propagation

    NASA Astrophysics Data System (ADS)

    Long, E. J.; Hargrave, G. K.; Jarvis, S.; Justham, T.; Halliwell, N.

    2006-07-01

    Experimental laser diagnostic data is presented for flame characterisation during interactions with toroidal vortices generated in the wake of an annular obstacle. A novel twin section combustion chamber has been utilised to allow the controlled formation of stable eddy structures into which a flame front can propagate. High speed laser sheet visualisation was employed to record the flow field and flame front temporal development and high-speed digital particle image velocimetry was used to quantify the velocity field of the unburnt mixture ahead of the flame front. Results provide characterisation of the toroidal vortex/flame front interaction for a range of vortex scales of and recirculation strengths.

  10. Plasma pressure effect on the multiple low-shear toroidal Alfven eigenmodes

    SciTech Connect

    Marchenko, V. S.

    2009-04-15

    It is shown that there is a critical thermal pressure gradient at which the polarizations of the multiple low-shear toroidal Alfven eigenmodes (TAEs) are reversed. Below the critical value, the TAE spectrum consists of two bands of the even (odd) modes located in the upper (lower) part of the toroidal Alfven gap, which is consistent with the zero-pressure limit [J. Candy, B. N. Breizman, J. W. Van Dam, and T. Ozeki, Phys. Lett. A 215, 299 (1996)]. Above the critical pressure, the odd (even) TAEs appear in the upper (lower) part of the gap.

  11. Experimental Evidence of a Zonal Magnetic Field in a Toroidal Plasma

    SciTech Connect

    Fujisawa, A.; Itoh, K.; Shimizu, A.; Nakano, H.; Ohshima, S.; Iguchi, H.; Matsuoka, K.; Okamura, S.; Minami, T.; Yoshimura, Y.; Nagaoka, K.; Ida, K.; Toi, K.; Takahashi, C.; Kojima, M.; Nishimura, S.; Isobe, M.; Suzuki, C.; Akiyama, T.; Nagashima, Y.

    2007-04-20

    A zonal magnetic field is found in a toroidal plasma. The magnetic field has a symmetric bandlike structure, which is uniform in the toroidal and poloidal directions and varies radially with a finite wavelength of mesoscale, which is analogous to zonal flows. A time-dependent bicoherence analysis reveals that the magnetic field should be generated by the background plasma turbulence. The discovery is classified as a new kind of phenomenon of structured magnetic field generation, giving insight into phenomena such as dipole field generation in rotational planets.

  12. Full-wave modeling of the O-X mode conversion in the Pegasus Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Köhn, A.; Jacquot, J.; Bongard, M. W.; Gallian, S.; Hinson, E. T.; Volpe, F. A.

    2011-12-01

    The potential of an EBW heating scheme via the O—X—B mode conversion scenarios has been investigated for the PEGASUS toroidal experiment. With the 2D full-wave code IPF-FDMC the O—X conversion has been modeled as a function of the poloidal and toroidal injection angles for a microwave frequency of 2.45 GHz. Based on preliminary Langmuir probe measurements in the mode conversion layer, different density profiles have been also included in the simulations. A maximum mode conversion efficiency of approximately 80 % has been found, making EBW heating an attractive heating scheme for PEGASUS.

  13. Flux tube train model for local turbulence simulation of toroidal plasmas

    SciTech Connect

    Watanabe, T.-H.; Sugama, H.; Ishizawa, A.; Nunami, M.

    2015-02-15

    A new simulation method for local turbulence in toroidal plasmas is developed by extending the conventional idea of the flux tube model. In the new approach, a train of flux tubes is employed, where flux tube simulation boxes are serially connected at each end along a field line so as to preserve a symmetry of the local gyrokinetic equations for image modes in an axisymmetric torus. Validity of the flux tube train model is confirmed against the toroidal ion temperature gradient turbulence for a case with a long parallel correlation of fluctuations, demonstrating numerical advantages over the conventional method in the time step size and the symmetry-preserving property.

  14. Tokamak Equilibria with Toroidal-Current Reversal in the Plasma Core Consistent with Experimental Data

    SciTech Connect

    Rodrigues, Paulo; Bizarro, Joao P. S.

    2007-09-21

    For the first time, tokamak equilibria with negative toroidal current flowing in the plasma core are computed consistently with available measurements from typical current-hole discharges. The equilibrium reconstruction, which leads to non-nested configurations where a system of axisymmetric magnetic islands unfolds, yields an overall good agreement between the computed and experimental plasma-pressure profiles, together with an excellent fit to motional-Stark-effect data. Therefore, considering the accuracy limits of present-day experimental results, care must be exercised when ruling out the existence of tokamak equilibria with central toroidal-current reversal, particularly if relying on reconstruction tools that cannot cope with non-nested configurations.

  15. The role of fluctuation-induced transport in a toroidal plasma with strong radial electric fields

    NASA Technical Reports Server (NTRS)

    Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J. Y.; Kim, Y. C.

    1981-01-01

    Previous work employing digitally implemented spectral analysis techniques is extended to demonstrate that radial fluctuation-induced transport is the dominant ion transport mechanism in an electric field dominated toroidal plasma. Such transport can be made to occur against a density gradient, and hence may have a very beneficial effect on confinement in toroidal plasmas of fusion interest. It is shown that Bohm or classical diffusion down a density gradient, the collisional Pedersen-current mechanism, and the collisionless electric field gradient mechanism described by Cole (1976) all played a minor role, if any, in the radial transport of this plasma.

  16. Observation of Cocurrent Toroidal Rotation in the EAST Tokamak with Lower-Hybrid Current Drive

    SciTech Connect

    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

    2011-06-10

    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.

  17. Effects of magnetic shear on toroidal rotation in tokamak plasmas with lower hybrid current drive.

    PubMed

    Rice, J E; Podpaly, Y A; Reinke, M L; Mumgaard, R; Scott, S D; Shiraiwa, S; Wallace, G M; Chouli, B; Fenzi-Bonizec, C; Nave, M F F; Diamond, P H; Gao, C; Granetz, R S; Hughes, J W; Parker, R R; Bonoli, P T; Delgado-Aparicio, L; Eriksson, L-G; Giroud, C; Greenwald, M J; Hubbard, A E; Hutchinson, I H; Irby, J H; Kirov, K; Mailloux, J; Marmar, E S; Wolfe, S M

    2013-09-20

    Application of lower hybrid (LH) current drive in tokamak plasmas can induce both co- and countercurrent directed changes in toroidal rotation, depending on the core q profile. For discharges with q(0) <1, rotation increments in the countercurrent direction are observed. If the LH-driven current is sufficient to suppress sawteeth and increase q(0) above unity, the core toroidal rotation change is in the cocurrent direction. This change in sign of the rotation increment is consistent with a change in sign of the residual stress (the divergence of which constitutes an intrinsic torque that drives the flow) through its dependence on magnetic shear. PMID:24093268

  18. Observation of cocurrent toroidal rotation in the EAST tokamak with lower-hybrid current drive.

    PubMed

    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

    2011-06-10

    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. PMID:21770511

  19. Theory of magneto-optical effects in helical multiferroic materials via toroidal magnon excitation

    NASA Astrophysics Data System (ADS)

    Miyahara, S.; Furukawa, N.

    2014-05-01

    We investigate dynamical magnetoelectric effect owing to Nambu-Goldstone magnon resonance in helical multiferroic materials. Using the spin wave expansion, we analyzed magneto- and electroactive modes in the J1-J2 Heisenberg model through the spin-current mechanism. Under external magnetic field, the Nambu-Goldstone magnons accompany dynamical toroidal moments, i.e., toroidal magnons, and their resonant absorption shows anomalous features such as nonreciprocal directional dichroism and natural circular dichroism. The estimation indicates that such effects are gigantic in helical magnets.

  20. Integration of Full Particle Orbit in Toroidal Plasmas Using Boris Scheme

    NASA Astrophysics Data System (ADS)

    Wei, Xishuo; Xiao, Yong

    2014-10-01

    When studying particle dynamics in high frequency electromagnetic waves, such as low hybrid wave heating, it is important to integrate full particle orbit accurately to very long time in tokamaks. Here we derived a formulation under magnetic coordinate based on the Boris Scheme, which can be used effectively to push particles in long time scale. After several hundred gyro-periods, the banana orbit can be observed and the toroidal precession frequency can be measured. The toroidal precession frequency is found to match that from the guiding center simulation. This new method shows superior numeric properties than the traditional Runge-Kutta method in terms of conserving particle energy and magnetic moment.