Compact toroid theory issues and approaches: a panel report

International Nuclear Information System (INIS)

1985-06-01

In the six years since the initiation of the compact toroid program by the Office of Fusion Energy, remarkable scientific advances have occurred on both field-reversed configurations (FRC) and spheromaks. This progress has been stimulated by a diverse experimental program with facilities at six laboratories, and by a small but nevertheless broad theoretical research effort encompassing more than a dozen institutions. The close coupling between theoretical and experimental programs has contributed immeasurably to this progress. This document offers guidance for future compact toroid theory by identifying and discussing the key physics issues. In most cases promising approaches to these issues are offered

Compact toroids with Alfvenic flows

International Nuclear Information System (INIS)

Wang Zhehui; Tang, X.Z.

2004-01-01

The Chandrasekhar equilibria form a class of stationary ideal magnetohydrodynamics equilibria stabilized by magnetic-field-aligned Alfvenic flows. Analytic solutions of the Chandrasekhar equilibria are explicitly constructed for both field-reversed configurations and spheromaks. Favorable confinement property of nested closed flux surfaces and the ideal magnetohydrodynamic stability of the compact toroids are of interest for both magnetic trapping of high energy electrons in astrophysics and confinement of high temperature plasmas in laboratory

Compact toroid fueling of the TdeV tokamak

International Nuclear Information System (INIS)

Martin, F.; Raman, R.; Xiao, C.; Thomas, J.

1993-01-01

Compact toroids have been proposed as a means of centrally fueling tokamak reactors because of the high velocity to which they can be accelerated. These are cold (T e ∼ 10 eV), high density (n e > 10 20 m -3 ) spheromak plasmoids that are accelerated in a magnetized Marshall gun. As a proof of principle experiment, a compact toroid fueler (CTF) has been developed for injection into the TdeV tokamak. The engineering goals of the experiment are to measure and minimize the impurity content of the CT plasma and the neutral gas remaining after CT formation. Also of importance is the effect of CT central fueling on the tokamak density profile and bootstrap current, and the relaxation rate of the density profile providing information on the confinement time of the CT fuel

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

Energy Technology Data Exchange (ETDEWEB)

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

Confinement and heating of high beta plasma with emphasis on compact toroids. Compact toroid research

International Nuclear Information System (INIS)

Vlases, G.C.; Pietrzyk, Z.A.

1984-11-01

Two older projects associated with very high energy density plasmas, specifically the High Density Field Reversed Configuration and the Liner Plasma Compression Experiment, have been completed. Attention has been turned to compact toroid experiments of more conventional density, and three experiments have been initiated. These include the Coaxial Slow Source Experiment, the Variable Length FRC Experiment, and Variable Angle CthetaP Experiment. In each case, the project was begun in order to provide basic plasma physics information on specific unresolved issues of progammatic importance to the national CT Program

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

International Nuclear Information System (INIS)

Siemon, R.E.

1981-03-01

This document contains papers contributed by the participants of the Third Symposium on Physics and Technology of Compact Toroids in the Magnetic Fusion Energy Program. Subjects include reactor aspects of compact toroids, energetic particle rings, spheromak configurations (a mixture of toroidal and poloidal fields), and field-reversed configurations

Toroidal nuclear fusion device

International Nuclear Information System (INIS)

Ito, Yutaka; Kasahara, Tatsuo; Takizawa, Teruhiro.

1975-01-01

Object: To design a device so as to be formed into a large-size and to arrange ports, through which neutral particles enter, in inclined fashion. Structure: Toroidal coils are wound about vacuum vessels which are divided into plural number. In the outer periphery of the vacuum vessels, ports are disposed inclined in the peripheral direction of the vacuum vessels and communicated with the vacuum vessels, and wall surfaces opposed to the ports of the toroidal coils adjacent at least the inclined sides of the ports are inclined substantially simularly to the port wall surfaces. (Kamimura, M.)

Compact toroidal energy storage device with relativistically densified electrons through the use of travelling magnetic waves

International Nuclear Information System (INIS)

Peter, W.; Faehl, R.J.

1983-01-01

A new concept for a small compact multimegajoule energy storage device utilizing relativistically densified electron beam circulating in a torus is presented. The electron cloud is produced through inductive charge injection by a travelling magnetic wave circulating the torus. Parameters are given for two representative toroidal energy storage devices, consisting of 1 m and 32 m in radius respectively, which could store more than 4 x 10 17 electrons and 30' MJ in energy. The concept utilizes the idea that large electric and magnetic fields can be produced by a partially space-charge neutralized intense relativistic electron beam which could become many orders of magnitude greater than the externally applied field confining the beam. In the present approach, the electron cloud densification can be achieved gradually by permitting multiple traversals of the magnetic wave around the torus. The magnetic mirror force acts on the orbital magnetic electron dipole moment and completely penetrates the entire electron cloud. As the electrons gain relativistic energies, the beam can be continuously densified at the front of the travelling wave, where the magnetic field is rising with time. The use of travelling magnetic wave to accelerate an electron cloud and the use of large electric field at the thusly accelerated cloud form the basis for a high beam intensity and hence high energy storage. Technical considerations and several potential applications, which include the driving of a powerful gyrotron, are discussed

An experimental investigation of the propagation of a compact toroid along curved drift tubes

International Nuclear Information System (INIS)

Fukumoto, N.; Inoo, Y.; Nomura, M.; Nagata, M.; Uyama, T.; Ogawa, H.; Kimura, H.; Uehara, U.; Shibata, T.; Kashiwa, Y.; Suzuki, S.; Kasai, S.

2004-01-01

Compact toroid (CT) injection is a viable technology for fuelling large tokamak reactors in the future. Experimental demonstration of CT injection has thus far been conducted using horizontal injection in the midplane of tokamak devices. However, recent analyses indicate adverse effects of the toroidal magnetic field on CT injection. In order to avoid these adverse effects, the CT would need to be injectable in any direction. We have therefore devised a curved drift tube to change the direction of CT propagation and have experimentally demonstrated its efficacy. It has been observed that a CT can be transported smoothly through curved drift tubes with 45 deg. and 90 deg. bends without any appreciable change in the CT parameters. The magnetic field, electron density and speed of CTs transported through both 45 deg. and 90 deg. bends are similar to those observed in a linear drift tube. (author)

CT-TRX1, a triggered-reconnection compact toroid experiment

International Nuclear Information System (INIS)

Hoffman, A.L.

1980-05-01

A new compact toroid experiment, CT-TRX1, based on the field reversed theta pinch is under construction. The unique feature of this experiment is the incorporation of several quasi-steady and pulsed magnets to carefully control the reconnection process. The motivation for this emphasis is to duplicate and extend the results reported by Kurtmullaev, et al., where delayed reconnection produced efficient axial shock heating and resulted in large diameter compact toroids which exhibited complete MHD stability for the 100 μsec decay time of their pulsed magnets. CT-TRX1 incorporates moderate E/sub theta/ radial shock heating, along with the triggered reconnection capability, to investigate the full range of conditions between the USSR experiments and the radial shock heated experiments at LASL, where m = 2 rotational instabilities occur. An additional feature of CT-TRX1 is the incorporation of a compound magnet which will provide long magnetic field decay times. The requirements for both high field quasi-steady outer magnets, and several high voltage, individually triggered pulsed inner magnets, present unique engineering design problems which are discussed

Fuelling effect of tangential compact toroid injection in STOR-M Tokamak

Energy Technology Data Exchange (ETDEWEB)

Onchi, T.; Liu, Y., E-mail: tao668@mail.usask.ca [Univ. of Saskatchewan, Dept. of Physics and Engineering Physics, Saskatoon, Saskatchewan (Canada); Dreval, M. [Univ. of Saskatchewan, Dept. of Physics and Engineering Physics, Saskatoon, Saskatchewan (Canada); Inst. of Plasma Physics NSC KIPT, Kharkov (Ukraine); McColl, D. [Univ. of Saskatchewan, Dept. of Physics and Engineering Physics, Saskatoon, Saskatchewan (Canada); Asai, T. [Inst. of Plasma Physics NSC KIPT, Kharkov (Ukraine); Wolfe, S. [Nihon Univ., Dept. of Physics, Tokyo (Japan); Xiao, C.; Hirose, A. [Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada)

2012-07-01

Compact torus injection (CTI) is the only known candidate for directly fuelling the core of a tokamak fusion reactor. Compact torus (CT) injection into the STOR-M tokamak has induced improved confinement accompanied by an increase in the electron density, reduction in Hα emission, and suppression of the saw-tooth oscillations. The measured change in the toroidal flow velocity following tangential CTI has demonstrated momentum injection into the STOR-M plasma. (author)

Quasistatic evolution of compact toroids

International Nuclear Information System (INIS)

Sgro, A.G.; Spencer, R.L.; Lilliequist, C.

1981-01-01

Some results are presented of simulations of the post formation evolution of compact toroids. The simulations were performed with a 1-1/2 D transport code. Such a code makes explicit use of the fact that the shapes of the flux surfaces in the plasma change much more slowly than do the profiles of the physical variables across the flux surfaces. Consequently, assuming that the thermodynamic variables are always equilibrated on a flux surface, one may calculate the time evolution of these profiles as a function of a single variable that labels the flux surfaces. Occasionally, during the calculation these profiles are used to invert the equilibrium equation to update the shapes of the flux surfaces. In turn, these shapes imply certain geometric cofficients, such as A = 2 >, which contain the geometric information required by the 1-D equations

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

Science.gov (United States)

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.

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

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T. [College of Science and Technology, Nihon University, 1-8-14 Kanda, Chiyoda-ku, Tokyo 1018308 (Japan); Gota, H.; Garate, E.; Allfrey, I.; Valentine, T.; Morehouse, M.; Roche, T.; Kinley, J.; Aefsky, S.; Cordero, M.; Waggoner, W.; Binderbauer, M. [Tri Alpha Energy, Inc., P.O. Box 7010 Rancho Santa Margarita, California 92688 (United States); Tajima, T. [Tri Alpha Energy, Inc., P.O. Box 7010 Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2016-05-15

A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10{sup 21} m{sup −3}, ∼40 eV, and 0.5–1.0 × 10{sup 19}, respectively.

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

International Nuclear Information System (INIS)

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.

2016-01-01

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"2"1 m"−"3, ∼40 eV, and 0.5–1.0 × 10"1"9, respectively.

Compact toroid formation, compression, and acceleration

International Nuclear Information System (INIS)

Degnan, J.H.; Bell, D.E.; Baca, G.P.; Dearborn, M.E.; Douglas, M.R.; Englert, S.E.; Englert, T.J.; Holmes, J.H.; Hussey, T.W.; Kiuttu, G.F.; Lehr, F.M.; Marklin, G.J.; Mullins, B.W.; Peterkin, R.E.; Price, D.W.; Roderick, N.F.; Ruden, E.L.; Turchi, P.J.; Coffey, S.K.; Seiler, S.W.; Bird, G.

1992-01-01

Research on the formation, compression, and acceleration of milligram Compact Toroids (CTs) will be discussed. This includes experiments with 2-stage coaxial gun discharges and calculations including 2D- MHD. The CTs are formed by 110 μf, 70 KV, 2 MA, 3 μs rise time discharges into 2 mg gas puffs in a 90 cm inner diameter, 7.6 cm gap coaxial gun with approximately 0.15 Tesla of radial-axial initial magnetic field. Reconnection at the neck of the toroidal magnetized plasma bubble extracted from the first stage gun forms the CT. Trapping, relaxation to a minimum energy Taylor state is observed with magnetic probe arrays. Low energy (few hundred KJ, 2 MA) acceleration in straight coaxial geometry, and high energy acceleration using a conical compression stage are discussed. The Phillips Laboratory 1,300 μf, 120 KV, 9.4 MJ SHIVA STAR capacitor bank is used for the acceleration discharge. The charging and triggering of the 36-module bank has been modified to permit use of any multiple of three modules. Highlights of fast photography, current, voltage, magnetic probe array, optical spectroscopy, interferometry, VUV, and higher energy radiation data and 2D-MHD calculations will be presented. Considerably more detail is presented in companion papers

Los Alamos Compact Toroid, fast liner, and High-Density Z-Pinch programs

International Nuclear Information System (INIS)

Linford, R.K.; Hammel, J.E.; Sherwood, H.R.

1982-01-01

The compact Toroid and High Density Z-Pinch are two of the plasma configurations presently being studied at Los Alamos. This paper summarizes these two programs along with the recently terminated Fast Liner Program. Included in this discussion is an analysis of compact Toroid formation techniques showing the tearing and reconnection of the fields that separate the spheromak from the radial fields of the coaxial source, and the final equilibrium state of the elongated FRC in the theta-pinch coil. In addition the typical dimensions of the geometry of the Fast Liner experiments are delineated Z-pinch and electrode assembly is displayed as is a graphic of the temporal behavior of the current required for radial equilibrium. Spheromak is examined in terms of formation, gross stability, and equilibrium and field reversed configuration is discussed in terms of gross stability, equilibrium, and confinement scaling

Compact toroid injection system for JFT-2M

Energy Technology Data Exchange (ETDEWEB)

Fukumoto, N. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan)]. E-mail: fukumotn@eng.u-hyogo.ac.jp; Ogawa, H. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Nagata, M. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Uyama, T. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Shibata, T. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Kashiwa, Y. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Suzuki, S. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Kusama, Y. [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan)

2006-11-15

The compact toroid (CT) injection system for JFT-2M is composed of a CT injector, a gas delivery and vacuum system, a power supply system, and a diagnostics system. In particular, the power supply system delivers high performance for CT formation and acceleration. The CT formation capacitor bank unit achieved a formation current of 350 kA with a rise time less than 10 {mu}s. Although the CT acceleration bank units are equipped with 14 ignitron switches instead of gap switches to attenuate the discharge noise level, an acceleration current of 400 kA with a short rise time of 9 {mu}s is controlled within a jitter of much less than 1 {mu}s. The resulting CT velocity and mass density satisfy the requirements for CT penetration into the tokamak plasma core at a toroidal field of 1 T. This CT injection system is thus suitable for CT injection in a middle-sized tokamak plasma such as the JFT-2M tokamak.

Compact toroid injection system for JFT-2M

International Nuclear Information System (INIS)

Fukumoto, N.; Ogawa, H.; Nagata, M.; Uyama, T.; Shibata, T.; Kashiwa, Y.; Suzuki, S.; Kusama, Y.

2006-01-01

The compact toroid (CT) injection system for JFT-2M is composed of a CT injector, a gas delivery and vacuum system, a power supply system, and a diagnostics system. In particular, the power supply system delivers high performance for CT formation and acceleration. The CT formation capacitor bank unit achieved a formation current of 350 kA with a rise time less than 10 μs. Although the CT acceleration bank units are equipped with 14 ignitron switches instead of gap switches to attenuate the discharge noise level, an acceleration current of 400 kA with a short rise time of 9 μs is controlled within a jitter of much less than 1 μs. The resulting CT velocity and mass density satisfy the requirements for CT penetration into the tokamak plasma core at a toroidal field of 1 T. This CT injection system is thus suitable for CT injection in a middle-sized tokamak plasma such as the JFT-2M tokamak

Application of plasma focus device to compression of toroidal plasma

International Nuclear Information System (INIS)

Ikuta, Kazunari

1980-01-01

A new concept of compressing a toroidal plasma using a plasma focus device is considered. Maximum compression ratio of toroidal plasma is determined merely by the initial density ratio of the toroidal plasma to a sheet plasma in a focus device because of the Rayleigh-Taylor instability. An initiation senario of plasma-linear is also proposed with a possible application of this concepts to the creation of a burning plasma in reversed field configurations, i.e., burning plasma vortex. (author)

Configuration development of a hydraulic press for preloading the toroidal field coils of the Compact Ignition Tokamak

International Nuclear Information System (INIS)

Lee, V.D.

1987-01-01

The Fusion Engineering Design Center (FEDC) is part of a national design team that is developing the conceptual design of the Compact Ignition Tokamak (CIT). To achieve a compact device with the minimum major radius, a vertical preload system is being developed to react the vertical separating force normally carried by the inboard leg of the toroidal field (TF) coils. The preload system is in the form of a hydraulic press. Challenges in the design include the development of hydraulic and structural systems for very large force requirements, which could interface with the CIT machine, while allowing maximum access to the top, bottom, and radial periphery of the machine. Maximum access is necessary for maintenance, diagnostics, instrumentation, and control systems. Materials used in the design must function in the nuclear environment and in the presence of high magnetic fields. This paper presents the configuration development of the hydraulic press used to vertically preload the CIT device

Field-reversed experiments (FRX) on compact toroids

Energy Technology Data Exchange (ETDEWEB)

Armstrong, W.T.; Linford, R.K.; Lipson, J.; Platts, D.A.; Sherwood, E.G.

1981-11-01

Equilibrium, stability, and confinement properties of compact toroids produced in field-reversed theta-pinch experiments (FRX) are reported. Two experimental facilities, FRX-A and FRX-B, have been used to study highly elongated compact toroid plasmas confined in a purely poloidal field geometry. Spatial scans and fill pressure scaling of the equilibrium plasma parameters are presented. Plasma conditions range from T/sub e/approx.150 eV, T/sub i/approx.800 eV, n/sub m/approx.1 x 10/sup 15/ cm/sup -3/ to T/sub e/approx.100 eV, T/sub i/approx.150 eV, n/sub m/approx.4 x 10/sup 15/ cm/sup -3/. Typical confined plasma dimensions are: major radius Rapprox.4 cm, minor radius aapprox.2 cm, and total length 35--50 cm. The plasma configuration remains in a stable equilibrium for up to 50 ..mu..sec followed by the destructive n = 2 rotational instability. The stable period prior to the onset of the rotational mode is up to one hundred times greater than characteristic Alfven transit times of the plasma. This stable period increases and the mode growth rate decreases with increased a/rho/sub i/ (where rho/sub i/ is the ion gyroradius). Agreement of experimental and theoretical mode frequencies for the instability is observed. Preferential particle loss has been proposed as a likely cause of rotation. The particle inventory at the onset of the instability is consistent with this hypothesis. The particle loss rate is also consistent with the predicted anomalous transport near the separatrix. Contributions to rotational instability from diffusion, end-shorting, equipartition, and compression are also discussed.

Field-reversed experiments (FRX) on compact toroids

International Nuclear Information System (INIS)

Armstrong, W.T.; Linford, R.K.; Lipson, J.; Platts, D.A.; Sherwood, E.G.

1981-01-01

Equilibrium, stability, and confinement properties of compact toroids produced in field-reversed theta-pinch experiments (FRX) are reported. Two experimental facilities, FRX-A and FRX-B, have been used to study highly elongated compact toroid plasmas confined in a purely poloidal field geometry. Spatial scans and fill pressure scaling of the equilibrium plasma parameters are presented. Plasma conditions range from T/sub e/approx.150 eV, T/sub i/approx.800 eV, n/sub m/approx.1 x 10 15 cm -3 to T/sub e/approx.100 eV, T/sub i/approx.150 eV, n/sub m/approx.4 x 10 15 cm -3 . Typical confined plasma dimensions are: major radius Rapprox.4 cm, minor radius aapprox.2 cm, and total length 35--50 cm. The plasma configuration remains in a stable equilibrium for up to 50 μsec followed by the destructive n = 2 rotational instability. The stable period prior to the onset of the rotational mode is up to one hundred times greater than characteristic Alfven transit times of the plasma. This stable period increases and the mode growth rate decreases with increased a/rho/sub i/ (where rho/sub i/ is the ion gyroradius). Agreement of experimental and theoretical mode frequencies for the instability is observed. Preferential particle loss has been proposed as a likely cause of rotation. The particle inventory at the onset of the instability is consistent with this hypothesis. The particle loss rate is also consistent with the predicted anomalous transport near the separatrix. Contributions to rotational instability from diffusion, end-shorting, equipartition, and compression are also discussed

Comparison study of toroidal-field divertors for a compact reversed-field pinch reactor

International Nuclear Information System (INIS)

Bathke, C.G.; Krakowski, R.A.; Miller, R.L.

1985-01-01

Two divertor configurations for the Compact Reversed-Field Pinch Reactor (CRFPR) based on diverting the minority (toroidal) field have been reported. A critical factor in evaluating the performance of both poloidally symmetric and bundle divertor configurations is the accurate determination of the divertor connection length and the monitoring of magnetic islands introduced by the divertors, the latter being a three-dimensional effect. To this end the poloidal-field, toroidal-field, and divertor coils and the plasma currents are simulated in three dimensions for field-line tracings in both the divertor channel and the plasma-edge regions. The results of this analysis indicate a clear preference for the poloidally symmetric toroidal-field divertor. Design modifications to the limiter-based CRFPR design that accommodate this divertor are presented

Simulated and experimental compression of a compact toroid

Energy Technology Data Exchange (ETDEWEB)

Johnson, J N; Hwang, D Q; Horton, R D; Evans, R W; Owen, J M

2009-05-06

We present simulation results and experimental data for the compression of a compact toroid by a conducting nozzle without a center electrode. In both simulation and experiment, the flow of the plasma is greatly obstructed by even modest magnetic fields. A simple mechanism for this obstruction is suggested by our simulations. In particular, the configuration of the plasmoid's magnetic field plays a significant role in the success of the experiment. We analyze two types of plasma configurations under compression and demonstrate that the results from the simulations matches those from the experiments, and that the mechanism predicts the different behaviors observed in the two cases.

Microwave produced plasma in a Toroidal Device

Science.gov (United States)

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.

System and method of operating toroidal magnetic confinement devices

Science.gov (United States)

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.

Compact toroid development: activity plan for field reversed configurations

International Nuclear Information System (INIS)

1984-06-01

This document contains the description, goals, status, plans, and approach for the investigation of the properties of a magnetic configuration for plasma confinement identified as the field reversed configuration (FRC). This component of the magnetic fusion development program has been characterized by its potential for physical compactness and a flexible range of output power. The included material represents the second phase of FRC program planning. The first was completed in February 1983, and was reported in DOE/ER-0160; Compact Toroid Development. This planning builds on that previous report and concentrates on the detailed plans for the next several years of the current DOE sponsored program. It has been deliberately restricted to the experimental and theoretical efforts possible within the present scale of effort. A third phase of this planning exercise will examine the subsequent effort and resources needed to achieve near term (1987 to 1990) FRC technical objectives

Development of Compact Toroid Injector for C-2 FRCs

Science.gov (United States)

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.

Los Alamos compact toroid, fast-liner, and high-density Z-pinch programs

Energy Technology Data Exchange (ETDEWEB)

Linford, R.K.; Sherwood, A.R.; Hammel, J.E.

1981-03-01

The Compact Toroid (CT) and High Density Z-Pinch (HDZP) are two of the plasma configurations presently being studied at Los Alamos. The purpose of these two programs, plus the recently terminated (May 1979) Fast Liner (FL) program, is summarized in this section along with a brief description of the experimental facilities. The remaining sections summarize the recent results and the experimental status.

Density Measurement of Compact Toroid with Mach-Zehnder Interferometer

Science.gov (United States)

Laufman-Wollitzer, Lauren; Endrizzi, Doug; Brookhart, Matt; Flanagan, Ken; Forest, Cary

2016-10-01

Utilizing a magnetized coaxial plasma gun (MCPG) built by Tri Alpha Energy, a dense compact toroid (CT) is created and injected at high speed into the Wisconsin Plasma Astrophysics Laboratory (WiPAL) vessel. A modified Mach-Zehnder interferometer from the Line-Tied Reconnection Experiment (LTRX) provides an absolute measurement of electron density. The interferometer is located such that the beam intersects the plasma across the diameter of the MCPG drift region before the CT enters the vessel. This placement ensures that the measurement is taken before the CT expand. Results presented will be used to further analyze characteristics of the CT. Funding provided by DoE, NSF, and WISE Summer Research.

MHD simulation study of compact toroid injection into magnetized plasmas

International Nuclear Information System (INIS)

Suzuki, Yoshio; Kishimoto, Yasuaki

2000-01-01

To understand the fuelling process in a fusion device by a compact toroid (CT) plasmoid injection method, we have carried out MHD numerical simulations where a spheromak-like CT (SCT) is injected into a magnetized target plasma region. So far, we revealed that the penetration depth of the SCT plasma becomes shorter than that estimated from the conducting sphere (CS) model, because in the simulation the Lorentz force of the target magnetic field sequentially decelerates the injected SCT while in the CS model only the magnetic pressure force acts as the deceleration mechanism. In this study, we represent the new theoretical model where the injected SCT is decelerated by both the magnetic pressure force and the magnetic tension force (we call it the non-slipping sphere (NS) model) and investigate in detail the deceleration mechanism of the SCT by comparison with simulation results. As a result, it is found that the decrease of the SCT kinetic energy in the simulation coincides with that in the NS model more than in the CS model. It means that not only the magnetic pressure force but also the magnetic tension force acts as the deceleration mechanism of the SCT. Furthermore, it is revealed that magnetic reconnection between the SCT magnetic field and the target magnetic field plays a role to relax the SCT deceleration. (author)

Behavior of Compact Toroid Injected into C-2U Confinement Vessel

Science.gov (United States)

Matsumoto, Tadafumi; Roche, T.; Allrey, I.; Sekiguchi, J.; Asai, T.; Conroy, M.; Gota, H.; Granstedt, E.; Hooper, C.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M.; Tajima, T.; the TAE Team

2016-10-01

The compact toroid (CT) injector system has been developed for particle refueling on the C-2U device. A CT is formed by a magnetized coaxial plasma gun (MCPG) and the typical ejected CT/plasmoid parameters are as follows: average velocity 100 km/s, average electron density 1.9 ×1015 cm-3, electron temperature 30-40 eV, mass 12 μg . To refuel particles into FC plasma the CT must penetrate the transverse magnetic field that surrounds the FRC. The kinetic energy density of the CT should be higher than magnetic energy density of the axial magnetic field, i.e., ρv2 / 2 >=B2 / 2μ0 , where ρ, v, and B are mass density, velocity, and surrounded magnetic field, respectively. Also, the penetrated CT's trajectory is deflected by the transverse magnetic field (Bz 1 kG). Thus, we have to estimate CT's energy and track the CT trajectory inside the magnetic field, for which we adopted a fast-framing camera on C-2U: framing rate is up to 1.25 MHz for 120 frames. By employing the camera we clearly captured the CT/plasmoid trajectory. Comparisons between the fast-framing camera and some other diagnostics as well as CT injection results on C-2U will be presented.

Simulations of Low-q Disruptions in the Compact Toroidal Hybrid Experiment

Science.gov (United States)

Howell, E. C.; Hanson, J. D.; Ennis, D. A.; Hartwell, G. J.; Maurer, D. A.

2017-10-01

Resistive MHD simulations of low-q disruptions in the Compact Toroidal Hybrid Device (CTH) are performed using the NIMROD code. CTH is a current-carrying stellarator used to study the effects of 3D shaping on MHD stability. Experimentally, it is observed that the application of 3D vacuum fields allows CTH to operate with edge safety factor less than 2.0. However, these low-q discharges often disrupt after peak current if the applied 3D fields are too weak. Nonlinear simulations are initialized using model VMEC equilibria representative of low-q discharges with weak vacuum transform. Initially a series of symmetry preserving island chains are excited at the q=6/5, 7/5, 8/5, and 9/5 rational surfaces. These island chains act as transport barriers preventing stochastic magnetic fields in the edge from penetrating into the core. As the simulation progresses, predominately m/n=3/2 and 4/3 instabilities are destabilized. As these instabilities grow to large amplitude they destroy the symmetry preserving islands leading to large regions of stochastic fields. A current spike and loss of core thermal confinement occurs when the innermost island chain (6/5) is destroyed. Work Supported by US-DOE Grant #DE-FG02-03ER54692.

A gas puff experiment for partial simulation of compact toroid formation on MARAUDER

International Nuclear Information System (INIS)

Englert, S.E.; Englert, T.J.; Degnan, J.H.; Gahl, J.M.

1994-01-01

Preliminary results will be reported of a single valve gas puff experiment to determine spatial and spectral distribution of a gas during the early ionization stages. This experiment has been developed as a diagnostic test-bed for partial simulation of compact toroid formation on MARAUDER. The manner in which the experimental hardware has been designed allows for a wide range of diagnostic access to evaluate early time evolution of the ionization process. This evaluation will help contribute to a clearer understanding of the initial conditions for the formation stage of the compact toroid in the MARAUDER experiment, where 60 of the same puff valves are used. For the experiment, a small slice of the MARAUDER cylindrical gas injection and expansion region geometry have been re-created but in cartesian coordinates. All of the conditions in the experiment adhere as closely as possible to the MARAUDER experiment. The timing, current rise time, capacitance, resistance and inductance are appropriate to both the simulation of one of the 60 puff valves and current delivery to the load. Both time-resolved images and spectral data have been gathered for visible light emission of the plasma. Processed images reveal characteristics of spatial distribution of the current. Spectral data provide information with respect to electron temperature and density, and entrainment of contaminants

Next generation toroidal devices

International Nuclear Information System (INIS)

Yoshikawa, Shoichi

1998-10-01

A general survey of the possible approach for the next generation toroidal devices was made. Either surprisingly or obviously (depending on one's view), the technical constraints along with the scientific considerations lead to a fairly limited set of systems for the most favorable approach for the next generation devices. Specifically if the magnetic field strength of 5 T or above is to be created by superconducting coils, it imposes minimum in the aspect ratio for the tokamak which is slightly higher than contemplated now for ITER design. The similar technical constraints make the minimum linear size of a stellarator large. Scientifically, it is indicated that a tokamak of 1.5 times in the linear dimension should be able to produce economically, especially if a hybrid reactor is allowed. For the next stellarator, it is strongly suggested that some kind of helical axis is necessary both for the (almost) absolute confinement of high energy particles and high stability and equilibrium beta limits. The author still favors a heliac most. Although it may not have been clearly stated in the main text, the stability afforded by the shearless layer may be exploited fully in a stellarator. (author)

Next generation toroidal devices

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, Shoichi [Princeton Plasma Physics Lab., Princeton Univ., NJ (United States)

1998-10-01

A general survey of the possible approach for the next generation toroidal devices was made. Either surprisingly or obviously (depending on one`s view), the technical constraints along with the scientific considerations lead to a fairly limited set of systems for the most favorable approach for the next generation devices. Specifically if the magnetic field strength of 5 T or above is to be created by superconducting coils, it imposes minimum in the aspect ratio for the tokamak which is slightly higher than contemplated now for ITER design. The similar technical constraints make the minimum linear size of a stellarator large. Scientifically, it is indicated that a tokamak of 1.5 times in the linear dimension should be able to produce economically, especially if a hybrid reactor is allowed. For the next stellarator, it is strongly suggested that some kind of helical axis is necessary both for the (almost) absolute confinement of high energy particles and high stability and equilibrium beta limits. The author still favors a heliac most. Although it may not have been clearly stated in the main text, the stability afforded by the shearless layer may be exploited fully in a stellarator. (author)

Remote replacement of TF [toroidal field] and PF [poloidal field] coils for the compact ignition tokamak

International Nuclear Information System (INIS)

Macdonald, D.; Watkin, D.C.; Hollis, M.J.; DePew, R.E.; Kuban, D.P.

1990-01-01

The use of deuterium-tritium fuel in the Compact Ignition Tokamak will require applying remote handling technology for ex-vessel maintenance and replacement of machine components. Highly activated and contaminated components of the fusion devices auxiliary systems, such as diagnostics and RF heating, must be replaced using remotely operated maintenance equipment in the test cell. In-vessel remote maintenance included replacement of divertor and first wall hardware, faraday shields, and for an in-vessel inspection system. Provision for remote replacement of a vacuum vessel sector, toroidal field coil or poloidal field ring coil was not included in the project baseline. As a result of recent coil failures experienced at a number of facilities, the CIT project decided to reconsider the question of remote recovery from a coil failure and, in January of 1990, initiated a coil replacement study. This study focused on the technical requirements and impact on fusion machine design associated with remote recovery from any coil failure

Studies on Plasmoid Merging using Compact Toroid Injectors

Science.gov (United States)

Allfrey, Ian; Matsumoto, Tadafumi; Roche, Thomas; Gota, Hiroshi; Edo, Takahiro; Asai, Tomohiko; Sheftman, Daniel; Osin Team; Dima Team

2017-10-01

C-2 and C-2U experiments have used magnetized coaxial plasma guns (MCPG) to inject compact toroids (CTs) for refueling the long-lived advanced beam-driven field-reversed configuration (FRC) plasma. This refueling method will also be used for the C-2W experiment. To minimize momentum transfer from the CT to the FRC two CTs are injected radially, diametrically opposed and coincident in time. To improve understanding of the CT characteristics TAE has a dedicated test bed for the development of CT injectors (CTI), where plasmoid merging experiments are performed. The test bed has two CTIs on axis with both axial and transverse magnetic fields. The 1 kG magnetic fields, intended to approximate the magnetic field strength and injection angle on C-2W, allow studies of cross-field transport and merging. Both CTIs are capable of injecting multiple CTs at up to 1 kHz. The resulting merged CT lives >100 μs with a radius of 25 cm. More detailed results of CT parameters will be presented.

System and method of operating toroidal magnetic confinement devices

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

Marcus, F.B.

1978-01-01

A poloidal magnetics system for a plasma producing device of toroidal configuration is provided that reduces both the total volt-seconds requirement and the magnitude of the field change at the toroidal field coils. The system utilizes an air core transformer wound between the toroidal field (TF) coils and the major axis outside the TF coils. Electric current in the primary windings of this transformer is distributed and the magnetic flux returned by air core windings wrapped outside the toroidal field coils. A shield winding that is closely coupled to the plasma carries a current equal and opposite to the plasma current. This winding provides the shielding function and in addition serves in a fashion similar to a driven conducting shell to provide the equilibrium vertical field for the plasma. The shield winding is in series with a power supply and a decoupling coil located outside the TF coil at the primary winding locations. The present invention requires much less energy than the usual air core transformer and is capable of substantially shielding the toroidal field coils from poloidal field flux

One-dimensional MHD simulations of MTF systems with compact toroid targets and spherical liners

Science.gov (United States)

Khalzov, Ivan; Zindler, Ryan; Barsky, Sandra; Delage, Michael; Laberge, Michel

2017-10-01

One-dimensional (1D) MHD code is developed in General Fusion (GF) for coupled plasma-liner simulations in magnetized target fusion (MTF) systems. The main goal of these simulations is to search for optimal parameters of MTF reactor, in which spherical liquid metal liner compresses compact toroid plasma. The code uses Lagrangian description for both liner and plasma. The liner is represented as a set of spherical shells with fixed masses while plasma is discretized as a set of nested tori with circular cross sections and fixed number of particles between them. All physical fields are 1D functions of either spherical (liner) or small toroidal (plasma) radius. Motion of liner and plasma shells is calculated self-consistently based on applied forces and equations of state. Magnetic field is determined by 1D profiles of poloidal and toroidal fluxes - they are advected with shells and diffuse according to local resistivity, this also accounts for flux leakage into the liner. Different plasma transport models are implemented, this allows for comparison with ongoing GF experiments. Fusion power calculation is included into the code. We performed a series of parameter scans in order to establish the underlying dependencies of the MTF system and find the optimal reactor design point.

Recent results of studies of acceleration of compact toroids

International Nuclear Information System (INIS)

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

1984-01-01

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

Compact toroid injection into C-2U

Science.gov (United States)

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.

Characterization of compact-toroid injection during formation, translation, and field penetration

Science.gov (United States)

Matsumoto, T.; Roche, T.; Allfrey, I.; Sekiguchi, J.; Asai, T.; Gota, H.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M.; Tajima, T.

2016-11-01

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ˜1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.

Characterization of compact-toroid injection during formation, translation, and field penetration

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T. [Nihon University, Chiyoda-ku, Tokyo 101-8308 (Japan); Roche, T.; Allfrey, I.; Gota, H.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); Tajima, T. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2016-11-15

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ∼1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.

Theory and MHD simulation of fuelling process by Compact Toroid (CT) injection

International Nuclear Information System (INIS)

Suzuki, Y.; Hayashi, T.; Kishimoto, Y.

2001-01-01

The fuelling process by a spheromak-like compact toroid (SCT) injection is investigated by using MHD numerical simulations, where the SCT is injected into a magnetized target plasma region corresponding to a fusion device. In our previous study, the theoretical model to determine the penetration depth of the SCT into the target region has been proposed based on the simulation results, in which the SCT is decelerated not only by the magnetic pressure force but also by the magnetic tension force. However, since both ends of the target magnetic field are fixed on the boundary wall in the simulation, the deceleration caused by the magnetic tension force would be overestimated. In this study, the dependence of the boundary condition of the target magnetic field on the SCT penetration process is examined. From these results, the theoretical model we have proposed is improved to include the effect that the wave length of the target magnetic field bent by the SCT penetration expands with the Alfven velocity. In addition, by carrying out the simulation with the torus domain, it is confirmed that the theoretical model is applicable to estimate the penetration depth of the SCT under such conditions. Furthermore, the dependence of the injection position (the side injection and the top/bottom injection) on the penetration process is examined. (author)

Design and initial operation of a two-color soft x-ray camera system on the Compact Toroidal Hybrid experiment

International Nuclear Information System (INIS)

Herfindal, J. L.; Dawson, J. D.; Ennis, D. A.; Hartwell, G. J.; Loch, S. D.; Maurer, D. A.

2014-01-01

A multi-camera soft x-ray diagnostic has been developed to measure the equilibrium electron temperature profile and temperature fluctuations due to magnetohydrodynamic activity on the Compact Toroidal Hybrid experiment. The diagnostic consists of three separate cameras each employing two 20-channel diode arrays that view the same plasma region through different beryllium filter thicknesses of 1.8 μm and 3.0 μm allowing electron temperature measurements between 50 eV and 200 eV. The Compact Toroidal Hybrid is a five-field period current-carrying stellarator, in which the presence of plasma current strongly modifies the rotational transform and degree of asymmetry of the equilibrium. Details of the soft x-ray emission, effects of plasma asymmetry, and impurity line radiation on the design and measurement of the two-color diagnostic are discussed. Preliminary estimates of the temperature perturbation due to sawtooth oscillations observed in these hybrid discharges are given

Toroidal Thermonuclear device

International Nuclear Information System (INIS)

Takizawa, Teruhiro; Shizuoka, Yoshihide.

1982-01-01

Purpose: To reduce the shielding capacity of a current breaker for a current transformer coil and to facilitate the manufacture and the assembly of the current transformer coil. Constitution: A first current transformer coil is provided between a vacuum container for enclosing a plasma and a toroidal magnetic field coil, and a secon current transformer coil is provided outside the toroidal magnetic field coil. The rise of the plasma current is performed by the variation in the current of the coil of the first transformer having high electromagnetic coupling with the plasma current, and the variation in the magnetic flux necessary for maintaining the plasma is performed by the variation in the current of the second transformer coil. In this manner, the current shielding capacity of the first transformer coil can be reduced to decrease the number of coil turns, thereby facilitating the manufacture and assembly. (Seki, T.)

Two and three dimensional imaging of compact toroid plasmas using fast photography

International Nuclear Information System (INIS)

Englert, S.E.; Bell, D.E.; Coffey, S.K.

1992-01-01

As is discussed in a companion paper, Degnan el al, fast photography is used as a visual diagnostic tool for high energy plasma research at the Phillips Laboratory. Both, two dimensional and three dimensional images, are gathered by using nanosecond and microsecond range fast photography techniques. A set of microchannel plate cameras and a fast framing camera are used to record images of a compact toroid plasma during formation and acceleration stages. These images are subsequently digitized and enhanced to bring out detailed information of interest. This spatial information is combined with other diagnostic results as well as theoretical models in order to build a more complete picture of the fundamental physics associated with high-energy plasmas

Compact toroids generated by a magnetized coaxial source in the CTX experiment

Energy Technology Data Exchange (ETDEWEB)

Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.

1981-01-01

Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 ..mu..s for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10/sup 14/ cm/sup -3/ for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2.

Compact toroids generated by a magnetized coaxial source in the CTX experiment

International Nuclear Information System (INIS)

Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.

1981-01-01

Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 μs for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10 14 cm -3 for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2

Control of Compact-Toroid Characteristics by External Copper Shell

Science.gov (United States)

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.

Operation in low edge safety factor regime and passive disruption avoidance due to stellarator rotational transform in the Compact Toroidal Hybrid

Science.gov (United States)

Pandya, M. D.; Ennis, D. A.; Hartwell, G. J.; Maurer, D. A.

2015-11-01

Low edge safety factor operation at a value less than two (q (a) = 1 /ttot (a) routine on the Compact Toroidal Hybrid device. Presently, the operational space of this current carrying stellarator extends down to q (a) = 1 . 2 without significant n = 1 kink mode activity after the initial plasma current rise of the discharge. The disruption dynamics of these low q (a) plasmas depend upon the fraction of rotational transform produced by external stellarator coils to that generated by the plasma current. We observe that when about 10% of the total rotational transform is supplied by the stellarator coils, low q (a) disruptions are passively suppressed and avoided even though q (a) disrupt, the instability precursors measured and implicated as the cause are internal tearing modes with poloidal, m, and toroidal, n, mode numbers of m / n = 3 / 2 and 4 / 3 observed by external magnetic sensors, and m / n = 1 / 1 activity observed by core soft x-ray emissivity measurements. Even though q (a) passes through and becomes much less than two, external n = 1 kink mode activity does not appear to play a significant role in the observed disruption phenomenology. This work is supported by US Department of Energy Grant No. DE-FG02-00ER54610.

Theoretical study on the laser-driven ion-beam trace probe in toroidal devices with large poloidal magnetic field

Science.gov (United States)

Yang, X.; Xiao, C.; Chen, Y.; Xu, T.; Yu, Y.; Xu, M.; Wang, L.; Wang, X.; Lin, C.

2018-03-01

Recently, a new diagnostic method, Laser-driven Ion-beam Trace Probe (LITP), has been proposed to reconstruct 2D profiles of the poloidal magnetic field (Bp) and radial electric field (Er) in the tokamak devices. A linear assumption and test particle model were used in those reconstructions. In some toroidal devices such as the spherical tokamak and the Reversal Field Pinch (RFP), Bp is not small enough to meet the linear assumption. In those cases, the error of reconstruction increases quickly when Bp is larger than 10% of the toroidal magnetic field (Bt), and the previous test particle model may cause large error in the tomography process. Here a nonlinear reconstruction method is proposed for those cases. Preliminary numerical results show that LITP could be applied not only in tokamak devices, but also in other toroidal devices, such as the spherical tokamak, RFP, etc.

Configuration development of a hydraulic press for preloading the toroidal field coils of the Compact Ignition Tokamak

International Nuclear Information System (INIS)

Lee, V.D.

1987-01-01

The Fusion Engineering Design Center (FEDC) is part of a national design team that is developing the conceptual design of the Compact Ignition Tokamak (CIT). To achieve a compact device with the minimum major radius, a vertical preload system is being developed to react the vertical separating force normally carried by the inboard leg of the toroidal field (TF) coils. The preload system is in the form of a hydraulic press. Challenges in the design include the development of hydraulic and structural systems for very large force requirements, which could interface with the CIT machine, while allowing maximum access to the top, bottom, and radial periphery of the machine. Maximum access is necessary for maintenance, diagnostics, instrumentation, and control systems. Materials used in the design must function in the nuclear environment and in the presence of high magnetic fields. The structural system developed is an arrangement in which the CIT device is installed in the jaws of the press. Large built-up beams above and below the CIT span the machine and deliver the vertical force to the center cylinder formed by the inboard legs of the TF coils. During the conceptual design study, the vertical force requirement has ranged between 25,000 and 52,000 t. The access requirement on top and bottom limits the width of the spanning beams. Nonmagnetic steel materials are also required because of operation in the high magnetic fields. In the hydraulic system design for the press, several options are being explored. These range from small-diameter jacks operating at very high pressure [228 MPa (33 ksi)] to large-diameter jacks operating at pressures up to 69 MPa (10 ksi). Configurations with various locations for the hydraulic cylinders have also been explored. The nuclear environment and maintenance requirements are factors that affect cylinder location. This paper presents the configuration development of the hydraulic press used to vertically preload the CIT device

Compact-Toroid fusion reactor based on the field-reversed theta pinch

International Nuclear Information System (INIS)

Hagenson, R.L.; Krakowski, R.A.

1981-03-01

Early scoping studies based on approximate, analytic models have been extended on the basis of a dynamic plasma model and an overall systems approach to examine a Compact Toroid (CTOR) reactor embodiment that uses a Field-Reversed Theta Pinch as a plasma source. The field-reversed plasmoid would be formed and compressionally heated to ignition prior to injection into and translation through a linear burn chamber, thereby removing the high-technology plasmoid source from the hostile reactor environment. Stabilization of the field-reversed plasmoid would be provided by a passive conducting shell located outside the high-temperature blanket but within the low-field superconducting magnets and associated radiation shielding. On the basis of this batch-burn but thermally steady-state approach, a reactor concept emerges with a length below approx. 40 m that generates 300 to 400 MWe of net electrical power with a recirculating power fraction less than 0.15

Engineering aspects of compact stellarators

International Nuclear Information System (INIS)

Nelson, B.E.; Benson, R.D.; Brooks, A.

2003-01-01

Compact stellarators could combine the good confinement and high beta of a tokamak with the inherently steady state, disruption-free characteristics of a stellarator. Two U.S. compact stellarator facilities are now in the conceptual design phase: the National Compact Stellarator Experiment (NCSX) and the Quasi- Poloidal Stellarator (QPS). NCSX has a major radius of 1.4 m and a toroidal field up to 2 T. The primary feature of both NCSX and QPS is the set of modular coils that provide the basic magnetic configuration. These coils represent a major engineering challenge due to the complex shape, precise geometric accuracy, and high current density of the windings. The winding geometry is too complex for conventional hollow copper conductor construction. Instead, the modular coils will be wound with flexible, multi strand cable conductor that has been compacted to a 75% copper packing fraction. Inside the NCSX coil set and surrounding the plasma is a highly contoured vacuum vessel. The vessel consists of three identical, 120 deg. segments that are bolted together at double sealed joints. The QPS device has a major radius of 0.9 m, a toroidal field of 1 T, and an aspect ratio of only 2.7. Instead of an internal vacuum vessel, the QPS modular coils will operate in an external vacuum tank. (author)

Overview, Progress, and Plans for the Compact Toroidal Hybrid Experiment

Science.gov (United States)

Hartwell, G. J.; Allen, N. R.; Ennis, D. A.; Hanson, J. D.; Howell, E. C.; Johnson, C. A.; Knowlton, S. F.; Kring, J. D.; Ma, X.; Maurer, D. A.; Ross, K. G.; Schmitt, J. C.; Traverso, P. J.; Williamson, E. N.

2017-10-01

The Compact Toroidal Hybrid (CTH) is an l = 2 , m = 5 torsatron/tokamak hybrid (R0 = 0.75 m, ap 0.2 m, and | B | disruption studies. The main goals of the CTH experiment are to study disruptive behavior as a function of applied 3D magnetic shaping, and to test and advance the V3FIT reconstruction code and NIMROD modeling of CTH. The disruptive density limit is observed to exceed the Greenwald limit as the vacuum transform is increased with no observed threshold for avoidance. Low-q operations (1.1 routine, with disruptions ceasing if the vacuum transform is raised above 0.07. Sawteeth are observed in CTH and have a similar phenomenology to tokamak sawteeth despite employing a 3D confining field. Application of vacuum transform has been demonstrated to reduce and eliminate the vertical drift of elongated discharges. Internal SXR diagnostics, in conjunction with external magnetics, extend the range of reconstruction accuracy into the plasma core. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

A short introduction to the status and motivation for reversed field pinch and compact toroid research

International Nuclear Information System (INIS)

Dreicer, H.

1987-09-01

Potential commercial fusion power systems must be acceptable from a safety and environmental standpoint. They must also promise to be competitive with other sources of energy (i.e., fossil, fission, etc.) when considered from the standpoint of the cost of electricity (COE) and the unit direst cost (UDC) in ($/kWe). These costs are affected by a host of factors including recirculating power, plant availability, construction time, capital cost etc., and are, thus, influenced by technological complexity. In a attempt to meet these requirements, the emphasis of fusion research in the United States has been moving toward smaller, lower-cost systems. There is increased interest in higher beta tokamaks and stellarators, and in compact alternate concepts such as the Reversed Field Pinch (RFP) and the Compact Toroids (CTs) which are, in part, the subject of this paper

Recent results in the Los Alamos compact torus program

International Nuclear Information System (INIS)

Tuszewski, M.; Armstrong, W.T.; Barnes, C.W.

1983-01-01

A Compact Toroid is a toroidal magnetic-plasma-containment geometry in which no conductors or vacuum-chamber walls pass through the hole in the torus. Two types of compact toroids are studied experimentally and theoretically at Los Alamos: spheromaks that are oblate in shape and contain both toroidal and poloidal magnetic fields, and field-reversed configurations (FRC) that are very prolate and contain poloidal field only

Toroidal rotation studies in KSTAR

Science.gov (United States)

Lee, S. G.; Lee, H. H.; Yoo, J. W.; Kim, Y. S.; Ko, W. H.; Terzolo, L.; Bitter, M.; Hill, K.; KSTAR Team

2014-10-01

Investigation of the toroidal rotation is one of the most important topics for the magnetically confined fusion plasma researches since it is essential for the stabilization of resistive wall modes and its shear plays an important role to improve plasma confinement by suppressing turbulent transport. The most advantage of KSTAR tokamak for toroidal rotation studies is that it equips two main diagnostics including the high-resolution X-ray imaging crystal spectrometer (XICS) and charge exchange spectroscopy (CES). Simultaneous core toroidal rotation and ion temperature measurements of different impurity species from the XICS and CES have shown in reasonable agreement with various plasma discharges in KSTAR. It has been observed that the toroidal rotation in KSTAR is faster than that of other tokamak devices with similar machine size and momentum input. This may due to an intrinsically low toroidal field ripple and error field of the KSTAR device. A strong braking of the toroidal rotation by the n = 1 non-resonant magnetic perturbations (NRMPs) also indicates these low toroidal field ripple and error field. Recently, it has been found that n = 2 NRMPs can also damp the toroidal rotation in KSTAR. The detail toroidal rotation studies will be presented. Work supported by the Korea Ministry of Science, ICT and Future Planning under the KSTAR project.

Whole Device Modeling of Compact Tori: Stability and Transport Modeling of C-2W

Science.gov (United States)

Dettrick, Sean; Fulton, Daniel; Lau, Calvin; Lin, Zhihong; Ceccherini, Francesco; Galeotti, Laura; Gupta, Sangeeta; Onofri, Marco; Tajima, Toshiki; TAE Team

2017-10-01

Recent experimental evidence from the C-2U FRC experiment shows that the confinement of energy improves with inverse collisionality, similar to other high beta toroidal devices, NSTX and MAST. This motivated the construction of a new FRC experiment, C-2W, to study the energy confinement scaling at higher electron temperature. Tri Alpha Energy is working towards catalysing a community-wide collaboration to develop a Whole Device Model (WDM) of Compact Tori. One application of the WDM is the study of stability and transport properties of C-2W using two particle-in-cell codes, ANC and FPIC. These codes can be used to find new stable operating points, and to make predictions of the turbulent transport at those points. They will be used in collaboration with the C-2W experimental program to validate the codes against C-2W, mitigate experimental risk inherent in the exploration of new parameter regimes, accelerate the optimization of experimental operating scenarios, and to find operating points for future FRC reactor designs.

Elastic-plastic analysis of the toroidal field coil inner leg of the compact ignition tokamak

International Nuclear Information System (INIS)

Horie, T.

1987-07-01

Elastic-plastic analyses were made for the inner leg of the Compact Ignition Tokamak toroidal field (TF) coil, which is made of copper-Inconel composite material. From the result of the elastic-plastic analysis, the effective Young's moduli of the inner leg were determined by the analytical equations. These Young's moduli are useful for the three-dimensional, elastic, overall TF coil analysis. Comparison among the results of the baseline design (R = 1.324 m), the bucked pressless design, the 1.527-m major radius design, and the 1.6-m major radius design was also made, based on the elastic-plastic TF coil inner leg analyses

NCSX Toroidal Field Coil Design

International Nuclear Information System (INIS)

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

2005-01-01

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

Agglomeration of powders with a new-coupled vibration-compaction device

Directory of Open Access Journals (Sweden)

Serris Eric

2017-01-01

Full Text Available Inorganic powder recycling should be a crucial process for the “smart factories” in the future. A complex three-phase system (bauxite mixed with ordinary Portland cement and water with a new-coupled vibration-compaction device is studied. The compressive stress of compacts seems to be improved by using this device at low compaction pressure leaving the other characteristics unchanged. The tomographic study of macroscopic porosities shows differences in the pores repartitions inside vibrated and untreated compacts. Classic porosity repartition is shown in the classic compacted bauxite compacts whereas in the vibrated-compacted bauxite exhibits inhomogeneities. Despite this, we find these results quite promising for further investigations.

TPA device for demonstration

International Nuclear Information System (INIS)

1980-02-01

The TPA (torus plasma for amature) is a small race-trac type device made by the technical service division to demonstrate basic properties of plasma such as electron temperature, conductivity, effect of helical field for toroidal drift, and shape of plasma in mirror and cusp magnetic field in linear section. The plasmas are produced by RF discharge (-500W) and/or DC discharge (-30 mA) within glass discharge tube. Where major radius is 50 cm, length of linear section is 50 cm, toroidal magnetic field is 200 gauss. The device has been designed to be compact with only 100 V power source (-3.2 KW for the case without helical field) and to be full automatic sequence of operation. (author)

Gun-generated compact tori at Los Alamos

International Nuclear Information System (INIS)

Jarboe, T.R.; Henins, I.; Hoida, H.W.; Linford, R.K.; Marshall, J.; Platts, D.A.; Sherwood, A.R.

1982-01-01

We have generated compact toroids which can be made to come to rest in a cylindrical resistive flux conserver. They are observed to rotate so that their major axis is perpendicular to the axis of the flux conserver. Subsequently they appear to remain stationary and decay with a time constant of about 100 μs. We have also generated compact toroids in an oblate geometry which remain aligned with the axis of the flux conserver and decay with a time constant of 150 μs. The magnetic field reconnection time for compact toroid formation is measured in the latter case to be much shorter than the decay time

Interaction of a spheromak-like compact toroid with a high beta spherical tokamak plasma

International Nuclear Information System (INIS)

Hwang, D.Q.; McLean, H.S.; Baker, K.L.; Evans, R.W.; Horton, R.D.; Terry, S.D.; Howard, S.; Schmidt, G.L.

2000-01-01

Recent experiments using accelerated spheromak-like compact toroids (SCTs) to fuel tokamak plasmas have quantified the penetration mechanism in the low beta regime; i.e. external magnetic field pressure dominates plasma thermal pressure. However, fusion reactor designs require high beta plasma and, more importantly, the proper plasma pressure profile. Here, the effect of the plasma pressure profile on SCT penetration, specifically, the effect of diamagnetism, is addressed. It is estimated that magnetic field pressure dominates penetration even up to 50% local beta. The combination of the diamagnetic effect on the toroidal magnetic field and the strong poloidal field at the outer major radius of a spherical tokamak will result in a diamagnetic well in the total magnetic field. Therefore, the spherical tokamak is a good candidate to test the potential trapping of an SCT in a high beta diamagnetic well. The diamagnetic effects of a high beta spherical tokamak discharge (low aspect ratio) are computed. To test the penetration of an SCT into such a diamagnetic well, experiments have been conducted of SCT injection into a vacuum field structure which simulates the diamagnetic field effect of a high beta tokamak. The diamagnetic field gradient length is substantially shorter than that of the toroidal field of the tokamak, and the results show that it can still improve the penetration of the SCT. Finally, analytic results have been used to estimate the effect of plasma pressure on penetration, and the effect of plasma pressure was found to be small in comparison with the magnetic field pressure. The penetration condition for a vacuum field only is reported. To study the diamagnetic effect in a high beta plasma, additional experiments need to be carried out on a high beta spherical tokamak. (author)

Review of compact, alternate concepts for magnetic confinement fusion

International Nuclear Information System (INIS)

Nickerson, S.B.; Shmayda, W.T.; Dinner, P.J.; Gierszewski, P.

1984-06-01

This report documents a study of compact alternate magnetic confinement fusion experiments and conceptual reactor designs. The purpose of this study is to identify those devices with a potential to burn tritium in the near future. The bulk of the report is made up of a review of the following compact alternates: compact toroids, high power density tokamaks, linear magnetic systems, compact mirrors, reversed field pinches and some miscellaneous concepts. Bumpy toruses and stellarators were initially reviewed but were not pursued since no compact variations were found. Several of the concepts show promise of either burning tritium or evolving into tritium burning devices by the early 1990's: RIGGATRON, Ignitor, OHTE, Frascati Tokamak upgrade, several driven (low or negative net power) mirror experiments and several Reversed Field Pinch experiments that may begin operation around 1990. Of the above only the Frascati Tokamak Upgrade has had funds allocated. Also identified in this report are groups who may have tritium burning experiments in the mid to late 1990's. There is a discussion of the differences between the reviewed devices and the mainline tokamak experiments. This discussion forms the basis of recommendations for R and D aimed at the compact alternates and the applicability of the present CFFTP program to the needs of the compact alternates. These recommendations will be presented in a subsequent report

Engineering design of a toroidal divertor for the EBT-S fusion device. Final report, Phase II. EBT-S divertor project

International Nuclear Information System (INIS)

Mai, L.P.; Malick, F.S.

1981-01-01

The mechanical, structural, thermal, electrical, and vacuum design of a magnetic toroidal divertor system for the Elmo Bumpy Torus (EBT-S) is presented. The EBT-S is a toroidal magnetic fusion device located at the ORNL that operates under steady state conditions. The engineering of the divertor was performed during the second of three phases of a program aimed at the selection, design, fabrication, and installation of a magnetic divertor for EBT-S. The magnetic analysis of the toroidal divertor was performed during Phase I of the program and has been reported in a separate document. In addition to the details of the divertor design, the modest modifications that are required to the EBT-S device and facility to accommodate the divertor system are presented

Transport mechanisms acting in toroidal devices: a theoretician's view

International Nuclear Information System (INIS)

Carreras, B.A.

1992-01-01

Understanding the basic mechanisms of transport in toroidal confinement devices remains one of the more challenging scientific issues in magnetic confinement. At the same time, it is a critical issue for the magnetic fusion program. Recent progress in understanding fluctuations and transport has been fostered by the development and use of new diagnostics, bringing new perspectives on these studies. This has stimulated new theoretical developments. A view of the most recent issues and progress in this area is given. The role of long wavelengths in core transport and the relation between shear flows and turbulence at the plasma edge are the primary topics considered. (Author)

Experimental studies of plasma confinement in toroidal systems

International Nuclear Information System (INIS)

Bodin, H.A.B.; Keen, B.E.

1977-01-01

In this article the closed-line magnetic field approach to the plasma isolation and confinement problem in toroidal systems is reviewed. The theoretical aspects of closed-line magnetic field systems, indicating that topologically such systems are toroidal, are surveyed under the headings; topology of closed-line systems, equilibrium in different configurations and classification of toroidal devices, MHD stability, non-ideal effects in MHD stability, microscopic stability, and plasma energy loss. A section covering the experimental results of plasma confinement in toroidal geometry considers Stellerators, Tokamaks, toroidal pinch -the reversed-field pinch, screw pinches and high-β Tokamaks, Levitrons and multipoles (internal-ring devices), and miscellaneous toroidal containment devices. Recent achievements and the present position are discussed with reference to the status of Tokamak research, low-β stellerator research and high-β research. It is concluded from the continuing progress made in this research that the criteria for the magnetic containment of plasmas can be met. Further, it is concluded that the construction of a successful and economic fusion reactor is within the scope of advancing science and technology. 250 references. (U.K.)

Experimental studies of plasma confinement in toroidal systems

Energy Technology Data Exchange (ETDEWEB)

Bodin, H A.B.; Keen, B E [UKAEA, Abingdon. Culham Lab.

1977-12-01

In this article the closed-line magnetic field approach to the plasma isolation and confinement problem in toroidal systems is reviewed. The theoretical aspects of closed-line magnetic field systems, indicating that topologically such systems are toroidal, are surveyed under the headings; topology of closed-line systems, equilibrium in different configurations and classification of toroidal devices, MHD stability, non-ideal effects in MHD stability, microscopic stability, and plasma energy loss. A section covering the experimental results of plasma confinement in toroidal geometry considers Stellerators, Tokamaks, toroidal pinch -the reversed-field pinch, screw pinches and high-..beta.. Tokamaks, Levitrons and multipoles (internal-ring devices), and miscellaneous toroidal containment devices. Recent achievements and the present position are discussed with reference to the status of Tokamak research, low-..beta.. stellerator research and high-..beta.. research. It is concluded from the continuing progress made in this research that the criteria for the magnetic containment of plasmas can be met. Further, it is concluded that the construction of a successful and economic fusion reactor is within the scope of advancing science and technology. 250 references.

Resonance transparency with low-loss in toroidal planar metamaterial

Science.gov (United States)

Xiang, Tianyu; Lei, Tao; Hu, Sen; Chen, Jiao; Huang, Xiaojun; Yang, Helin

2018-03-01

A compact planar construction composed of asymmetric split ring resonators was designed with a low-loss, high Q-factor resonance transparency at microwave frequency. The singularity property of the proposed metamaterial owing to the enhanced toroidal dipole T is demonstrated via numerical and experimental methods. The transmission peak can reach up to 0.91 and the loss is perfectly repressed, which can be testified by radiated power, H-field distributions, and the imaginary parts of effective permittivity and permeability. The designed planar metamaterial may have numerous potential applications at microwave, terahertz, and optical frequency, e.g., for ultrasensitive sensing, slow-light devices, lasing spacers, even invisible information transfer.

Investigation of the toroidal dependence of first wall conditions in the Large Helical Device

International Nuclear Information System (INIS)

Hino, T.; Ashikawa, N.; Masuzaki, S.; Sagara, A.; Komori, A.; Yamauchi, Y.; Nobuta, Y.; Matsunaga, Y.

2010-11-01

The non-uniform wall conditions such as the fuel hydrogen retention and the erosion/deposition have been investigated in the Large Helical Device (LHD) by using toroidally and poloidally distributed material probes. They were installed in every experimental campaign from 2003 to 2010, and the evolutions of the wall conditions were clearly obtained. The wall conditions significantly depended on the operational procedures and the positions of in-vessel devices such as anodes for glow discharge and the ICRF antennas. The toroidal profiles for the amounts of retained hydrogen and helium, and the depth of wall erosion, were systematically measured. The hydrogen, helium and neon glow discharges have been conducted by using two anodes before and after the hydrogen or helium main discharges. The amount of retained hydrogen was large in the vicinity of the anodes, and drastically decreased as increase of the campaign number. This reduction well corresponds to the time period used for the hydrogen glow discharge conditioning. The erosion depth was large at the walls relatively close to the anodes, which is owing to the sputtering during the helium and neon glow discharges. The depositions of carbon and boron also depended on the positions of NBI and diborane gas inlet used for boronization, respectively. The amount of the retained helium was large at the walls close to the anodes owing to the helium glow discharge. The amount of retained helium became large at the walls close to the ICRF antennas owing to the implantation of high energy helium during the helium main discharge with the ICRF heating. In the present study, the toroidal dependences of the gas retention and the erosion/deposition in LHD were obtained, and the effects of the in-vessel devices on these plasma wall interactions were clarified. (author)

Flare-generated clouds as compact force-free toroidal configurations: magnetic measurements by the Vega-1 and Vega-2 space probes

International Nuclear Information System (INIS)

Ivanov, K.G.; Kharshiladze, A.F.; Eroshenko, E.G.; Styazhkin, V.A.

1988-01-01

Magnetic field experimental profiles, obtained during Vega-I and Vega-2 space vehicles passing through interplanetary cloud on the 16.02.1986, are compared with approximate theoretical profiles, taken from different hypotheses about such clouds structure. Maximum correlation of the theory and experiment is obtained with cloud presentation as flattened compact force-free toroid, which equatorial plane is approximately parallel to great circle plane, passing through flare on the 14.02.86 parallel to magnetic axis nearest to bipolar group flare

Proceedings of the seventh symposium on the physics and technology of compact toroids in the Magnetic Fusion Energy Program

International Nuclear Information System (INIS)

Sherwood, A.R.

1986-09-01

The Seventh Symposium on Compact Toroid (CT) Research was held in Santa Fe, New Mexico, on May 21-23, 1985. As has been the case for the last few CT symposia, CT research progress was reported in a combination of invited talks and poster sessions. The following record of these presentations in the form of four page papers is in keeping with the format followed in previous years. We have continued the practice of dividing the papers into three subject categories - spheromak, FRC (Field Reversed Configuration), and other (mostly particle rings)

US-Japan workshop on field-reversed configurations with steady-state high-temperature fusion plasmas and the 11th US-Japan workshop on compact toroids

International Nuclear Information System (INIS)

Barnes, D.C.; Fernandez, J.C.; Rej, D.J.

1990-05-01

The US-Japan Workshop on Field-Reversed Configurations with Steady-State High-Temperature Fusion Plasma and the 11th US-Japan Workshop on Compact Toroids were held at Los Alamos National Laboratory, Los Alamos, New Mexico on November 7--9, 1989. These proceedings contain the papers presented at the workshops as submitted by the authors. These papers have been indexed separately

US-Japan workshop on field-reversed configurations with steady-state high-temperature fusion plasmas and the 11th US-Japan workshop on compact toroids

Energy Technology Data Exchange (ETDEWEB)

Barnes, D.C.; Fernandez, J.C.; Rej, D.J. (comps.)

1990-05-01

The US-Japan Workshop on Field-Reversed Configurations with Steady-State High-Temperature Fusion Plasma and the 11th US-Japan Workshop on Compact Toroids were held at Los Alamos National Laboratory, Los Alamos, New Mexico on November 7--9, 1989. These proceedings contain the papers presented at the workshops as submitted by the authors. These papers have been indexed separately.

LASL Compact Torus Program

International Nuclear Information System (INIS)

Linford, R.K.; Armstrong, W.T.; Bartsch, R.R.

1981-01-01

The Compact Torus (CT) concept includes any axisymmetric toroidal plasma configuration, which does not require the linking of any material through the hole in the torus. Thus, the magnet coils, vacuum vessel, etc., have a simple cylindrical or spherical geometry instead of the toroidal geometry required for Tokamaks and RFP's. This simplified geometry results in substantial engineering advantages in CT reactor embodiments while retaining the good confinement properties afforded by an axisymmetric toroidal plasma-field geometry. CT's can be classified into three major types by using the ion gyro radius rho/sub i/ and the magnitude of the maximum toroidal field B/sub tm/

Neoclassical viscosities in NCSX and QPS with few toroidal periods and low aspect ratios

International Nuclear Information System (INIS)

Nishimura, S.; Mikkelsen, D.R.; Ku, L.P.; Mynick, H.E.; Zarnstorff, M.C.; Spong, D.A.; Hirshman, S.P.

2008-01-01

Previously reported benchmarking examples for the analytical formulas of neoclassical viscosities were made implicitly assuming applications in a future integrated simulation system for the LHD (Large Helical Device). Therefore the toroidal period numbers assumed there were mainly N=10. In this kind of calculation, however, an implicit (or sometimes explicit) assumption of ι/N<<1 is sometimes included. This assumption is included not only in simplified bounce averaged drift kinetic equations for ripple diffusions, but also in the equation before the averaging for non-bounce-averaged effects determining neoclassical parallel viscosity and the banana-plateau diffusions. To clarify the applicability of the analytical methods even for configurations with extremely low toroidal period numbers (required for low aspect ratios), we show here recent benchmarking examples in NCSX (National Compact Stellarator Experiment) with N=3 and QPS (Quasi-poloidal Stellarator) with N=2. (author)

Influence of external toroidal flux on low-aspect-ratio toroidal plasma

International Nuclear Information System (INIS)

Ikuno, S.; Natori, M.; Kamitani, A.

1999-01-01

In the HIST device, the external flux is generated by two kinds of currents: the current I s flowing along the symmetry axis and the bias coil current I D . The influence of the external flux on the MHD equilibrium and stability of the low-aspect-ratio toroidal plasma in the HIST device is investigated numerically. Equilibrium configurations of the low-aspect-ratio toroidal plasma in the HIST device are numerically determined by means of the combination of FDM and BEM. The influence of I s and I D on their stability is also investigated by using the Mercier criterion. The results of computations show that the Mercier limit decreases to zero with increasing I s and with decreasing I D . Moreover, either a further increase in I s or a further decrease in I D raises the Mercier limit considerably. Besides, the equilibrium configuration in the HIST device changes its state from spheromak through ultra-low q to tokamak with increasing I s and with decreasing I D . (author)

''Compact toroid research''

International Nuclear Information System (INIS)

Vlases, G.C.

1989-01-01

During the period from August 1988 to August 1989, the CSS project has made progress in three areas: The Coaxial Slow Source Upgrade CSSU version of the device was operated until January of 1989. In the Fall of 1988 Langmuir probes were installed to measure the end losses, the Thomson scattering system was made more sensitive, and a more detailed scan with internal magnetic probes was performed. Since then, the CSSU-centered work has concentrated on refining the analysis and interpretation of data. The CSS device was rebuilt as CSSP in the period Jan--June 1989, and began operation on July 3, 1989. Simultaneously, a new data acquisition and processing system based on a Vax 3200 workstation and MDS and IDL software was developed. The COAX 2 code was significant improved by the treatment of hydrogen ionization, including the radiative loss terms, and the inclusion of a more consistent transport and impurity radiation package. The improved code was used both to interpret the results of the CSSU experiments, and to predict performance for the CSSP and CSS2 devices. Details of these three areas of progress are given in the following sections

Feedback control of resistive wall modes in toroidal devices

International Nuclear Information System (INIS)

Liu, Y.Q.

2002-01-01

Active feedback of resistive wall modes is investigated using cylindrical theory and toroidal calculations. For tokamaks, good performance is obtained by using active coils with one set of coils in the poloidal direction and sensors detecting the poloidal field inside the first wall, located at the outboard mid-plane. With suitable width of the feedback coil such a system can give robust control with respect to variations in plasma current, pressure and rotation. Calculations are shown for ITER-like geometry with a double wall. The voltages and currents in the active coils are well within the design limits for ITER. Calculations for RFP's are presented for a finite number of coils both in the poloidal and toroidal directions. With 4 coils in the poloidal and 24 coils in the toroidal direction, all non-resonant modes can be stabilized both at high and low theta. Several types of sensors, including radial and internal poloidal or toroidal sensors, can stabilize the RWM, but poloidal sensors give the most robust performance. (author)

High beta plasma operation in a toroidal plasma producing device

International Nuclear Information System (INIS)

Clarke, J.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

Toroidal Superheavy Nuclei in Skyrme-Hartree-Fock Approach

International Nuclear Information System (INIS)

Staszczak, A.; Wong, Cheuk-Yin

2009-01-01

Within the self-consistent constraint Skyrme-Hartree-Fock+BCS model (SHF+BCS), we found equilibrium toroidal nuclear density distributions in the region of superheavy elements. For nuclei with a sufficient oblate deformation (Q 20 < -200 b), it becomes energetically favorable to change the genus of nuclear surface from 0 to 1, i.e., to switch the shape from a biconcave disc to a torus. The energy of the toroidal (genus=1) SHF+BCS solution relative to the compact (genus=0) ground state energy is strongly dependent both on the atomic number Z and the mass number A. We discuss the region of Z and A where the toroidal SHF+BCS total energy begins to be a global minimum

Ideal magnetohydrodynamic simulations of low beta compact toroid injection into a hot strongly magnetized plasma

Energy Technology Data Exchange (ETDEWEB)

Liu, Wei [Los Alamos National Laboratory; Hsu, Scott [Los Alamos National Laboratory; Li, Hui [Los Alamos National Laboratory

2009-01-01

We present results from three-dimensional ideal magnetohydrodynamic simulations of low {beta} compact toroid (CT) injection into a hot strongly magnetized plasma, with the aim of providing insight into CT fueling of a tokamak with parameters relevant for ITER (International Thermonuclear Experimental Reactor). A regime is identified in terms of CT injection speed and CT-to-background magnetic field ratio that appears promising for precise core fueling. Shock-dominated regimes, which are probably unfavorable for tokamak fueling, are also identified. The CT penetration depth is proportional to the CT injection speed and density. The entire CT evolution can be divided into three stages: (1) initial penetration, (2) compression in the direction of propagation and reconnection, and (3) coming to rest and spreading in the direction perpendicular to injection. Tilting of the CT is not observed due to the fast transit time of the CT across the background plasma.

Effect of loss cone on confinement in toroidal helical device

International Nuclear Information System (INIS)

Itoh, K.; Itoh, S.-I.; Fukuyama, A.; Hanatani, K.

1988-12-01

Analytical estimation is given on the loss cone in the toroidal helical devices in the presence of the radial electric field and the modulation of the helical ripple. The minimum energy of particles entering the loss cone is calculated. The modulation is not always effective in reducing the loss in the presence of the radial electric field. The plasma loss due to the loss cone is estimated in the collisionless limit. The radial electric field is estimated in the presence of the loss cone. It is found that the transition to the solution with positive radial electric field, which is necessary to achieve the high-ion-temperature mode, becomes difficult. This difficulty is large for the systems with the small helical ripple. (author)

High current density toroidal pinch discharges with weak toroidal fields

International Nuclear Information System (INIS)

Brunsell, P.; Brzozowski, J.; Drake, J.R.; Hellblom, G.; Kaellne, E.; Mazur, S.; Nordlund, P.

1990-01-01

Toroidal discharges in the ultralow q regime (ULQ) have been studied in the rebuilt Extrap TI device. ULQ discharges are sustained for pulse lengths exceeding 1 ms, which corresponds to more than 10 resistiv shell times. Values for the safety factor at the vacuum vessel wall are between rational values: 1/(n+1) -2 . The magnetic fluctuation level increases during the transition between rational values of q(a). For very low values of q(a), the loop voltage increases and the toroidal field development in the discharge exhibits the characteristic behaviour of the setting-up phase of a field reversed pinch. (author) 1 ref., 2 figs., 1 tab

Irradiation and testing of compact ignition tokamak toroidal field coil insulation materials

International Nuclear Information System (INIS)

Kanemoto, G.K.; Sherick, M.J.; Sparks, D.C.

1990-05-01

This report documents the results of an irradiation and testing program performed on behalf of Martin Marietta Energy Systems, Inc. in support of the Compact Ignition Tokamak Research and Development program. The purpose of the irradiation and testing program was to determine the effects of neutron and gamma irradiation on the mechanical and electrical properties of candidate toroidal field coil insulation materials. Insulation samples were irradiated in the Advanced Test Reactor (ATR) in a large I-hole. The insulation samples were irradiated within a lead shield to reduce exposure to gamma radiation to better approximate the desired ration of neutron to gamma exposure. Two different exposure levels were specified for the insulation samples. To accomplish this, the samples were encapsulated in two separate aluminum capsules; the capsules positioned at the ATR core mid-plane and at the top of the fueled region to take advantage of the axial cosine distribution of the neutron and gamma flux; and by varying the length of irradiation time of the two capsules. Disassembly of the irradiated capsules and testing of the insulation samples were performed at the Test Reactor Area (TRA) Hot Cell Facilities. Testing of the samples included shear compression static, shear compression fatigue, flexure static, and electrical resistance measurements

Three-dimensional simulation study of compact toroid plasmoid injection into magnetized plasmas

International Nuclear Information System (INIS)

Suzuki, Y.; Watanabe, T.-H.; Sato, T.; Hayashi, T.

1999-04-01

Three-dimensional dynamics of a compact toroid (CT) plasmoid, which is injected into a magnetized target plasma region is investigated by using magnetohydrodynamic (MHD) numerical simulations. It is found that the process of the CT penetration into this region is much more complicated than what has been analyzed so far by using a conducting sphere (CS) model. The injected CT suffers from a tilting instability, which grows with the similar time scale as the CT penetration. The instability is accompanied by magnetic reconnection between the CT magnetic field and the target magnetic field, which disrupts the magnetic configuration of the CT. Magnetic reconnection plays a role to supply the high density plasma initially confined in the CT magnetic field into the target region. Also, the penetration depth of the CT high density plasma is examined. It is shown to be shorter than that estimated from the CS model. The CT high density plasma is decelerated mainly by the Lorentz force of the target magnetic field, which includes not only the magnetic pressure force but also the magnetic tension force. Furthermore, by comparing the CT plasmoid injection with the bare plasmoid injection, magnetic reconnection is considered to relax the magnetic tension force, that is the deceleration of the CT plasmoid. (author)

A 3-MA compact-toroid-plasma-flow-switched plasma focus demonstration experiment on Shiva Star

Energy Technology Data Exchange (ETDEWEB)

Kiuttu, G F; Degnan, J H [Phillips Lab., Kirtland AFB, NM (United States). High Energy Sources Div.; Graham, J D [Maxwell Labs., Albuquerque, NM (United States); and others

1997-12-31

A novel dense plasma focus experiment using the Shiva Star capacitor bank is described. The experiment uses a compact toroid (CT) magnetized plasma flow switch (PFS) to initiate the focus implosion. The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to the gas puff central load. The inertia of the 1 mg CT and the work that must be done in compressing the internal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 - 10 {mu}s, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. K shell x-ray yields using neon gas were as high as 1 kJ, and 10{sup 8} neutrons were produced in a deuterium gas focus. (author). 4 figs., 10 refs.

A 3-MA compact-toroid-plasma-flow-switched plasma focus demonstration experiment on Shiva Star

International Nuclear Information System (INIS)

Kiuttu, G.F.; Degnan, J.H.

1996-01-01

A novel dense plasma focus experiment using the Shiva Star capacitor bank is described. The experiment uses a compact toroid (CT) magnetized plasma flow switch (PFS) to initiate the focus implosion. The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to the gas puff central load. The inertia of the 1 mg CT and the work that must be done in compressing the internal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 - 10 μs, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. K shell x-ray yields using neon gas were as high as 1 kJ, and 10 8 neutrons were produced in a deuterium gas focus. (author). 4 figs., 10 refs

Active trajectory control for a heavy ion beam probe on the compact helical system

International Nuclear Information System (INIS)

Fujisawa, A.; Iguchi, H.; Lee, S.; Crowley, T.P.; Hamada, Y.; Hidekuma, S.; Kojima, M.

1996-05-01

A 200 keV heavy ion beam probe (HIBP) on the Compact Helical System torsatron/heliotron uses a newly proposed method in order to control complicated beam trajectories in non-axisymmetrical devices. As a result, the HIBP has successfully measured potential profiles of the toroidal helical plasma. The article will describe the results of the potential profile measurements, together with the HIBP hardware system and procedures to realize the method. (author)

Compact Commercial Tokamak Reactor (CCTR): a concept for a 500-MWe commercial-tokamak fusion system

International Nuclear Information System (INIS)

Gillen, T.J.

1980-11-01

A detailed set of self-consistent parameters and costs for the conceptual design of a Compact Commercial Tokamak Reactor (CCTR) is given. Several of the basic design features are the following: an ignited plasma with a major radius of 4.9 m and minor radius of 1.4 m; a net electrical output of 500 MW; a borated-water-cooled, stainless steel shield; and a toroidal field of 12 T at the coil. The design, which utilizes the Westinghouse computer code for the COsting And Sizing of D-T burning Tokamaks (COAST), mainly provides the sizes and geometries associated with the definition of the main component features for which a detailed engineering design can be effectively undertaken. Design study alternatives, including a neutral beam driven design option, a design option with a toroidal field of 13 T at the coil, and a tungsten-shielded option are considered for the CCTR. Also included is the conceptual design of a Compact Fusion Engineering Device

Compact Toroid Theory Planning Workshop. A panel report to the Director, Division of Applied Plasma Physics, Office of Fusion Energy

International Nuclear Information System (INIS)

1980-07-01

The purpose of the Workshop was to identify the most important physics issues that need to be addressed in the near term in order to assure the optimal design and timely interpretation of Compact Toroid (CT) experiments. The Panel was also asked to assess the levels of effort required to obtain priority information on appropriate time scales compatible with DOE plans to design a CT proof-of-principle experiment. The fiscal year cost anticipated for the effort recommended by the Workshop Panel (excluding costs for computing) is estimated to be approximately $5.7M. CT theory is currently funded at a level of approximately $2.0M per year

Compact integrated optical devices for optical sensor and switching applications

NARCIS (Netherlands)

Kauppinen, L.J.

2010-01-01

This thesis describes the design, fabrication, and characterization of compact optical devices for sensing and switching applications. Our focus has been to realize the devices using CMOS-compatible fabrication processes. Particularly the silicon photonics fabrication platform, ePIXfab, has been

Advanced Toroidal Facility

International Nuclear Information System (INIS)

Johnson, R.L.

1985-01-01

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

Compact toroid injection fueling in a large field-reversed configuration

Science.gov (United States)

Asai, T.; Matsumoto, T.; Roche, T.; Allfrey, I.; Gota, H.; Sekiguchi, J.; Edo, T.; Garate, E.; Takahashi, Ts.; Binderbauer, M.; Tajima, T.

2017-07-01

A repetitively driven compact toroid (CT) injector has been developed for the large field-reversed configuration (FRC) facility of the C-2/C-2U, primarily for particle refueling. A CT is formed and injected by a magnetized coaxial plasma gun (MCPG) exclusively developed for the C-2/C-2U FRC. To refuel the particles of long-lived FRCs, multiple CT injections are required. Thus, a multi-stage discharge circuit was developed for a multi-pulsed CT injection. The drive frequency of this system can be adjusted up to 1 kHz and the number of CT shots per injector is two; the system can be further upgraded for a larger number of injection pulses. The developed MCPG can achieve a supersonic ejection velocity in the range of ~100 km s-1. The key plasma parameters of electron density, electron temperature and the number of particles are ~5  ×  1021 m-3, ~30 eV and 0.5-1.0  ×  1019, respectively. In this project, single- and double-pulsed counter CT injection fueling were conducted on the C-2/C-2U facility by two CT injectors. The CT injectors were mounted 1 m apart in the vicinity of the mid-plane. To avoid disruptive perturbation on the FRC, the CT injectors were operated at the lower limit of the particle inventory. The experiments demonstrated successful refueling with a significant density build-up of 20-30% of the FRC particle inventory per single CT injection without any deleterious effects on the C-2/C-2U FRC.

Advanced Toroidal Facility (ATF)

International Nuclear Information System (INIS)

Thompson, P.B.

1985-01-01

The Advanced Toroidal Facility (ATF) is a new magnetic plasma confinement device, under construction at Oak Ridge National Laboratory (ORNL), which will lead to improvements in toroidal magnetic fusion reactors. ATF is a type of stellarator known as a torsatron which theoretically has the capability at greater than or equal to8% beta in steady state. The ATF plasma has a major radius of 2.1 m, an average minor radius of 0.3 m, and a field of 2 T for a 5-s duration or 1 T steady state. The ATF device consists of a helical field (HF) coil set, a set of poloidal field (PF) coils, an exterior shell structure to support the coils, and a thin helically contoured vacuum vessel inside the coils. The ATF replaces the ISX-B tokamak at ORNL and will use the ISX-B auxiliary systems including 4 MW of neutral injection heating and 0.2 MW of electron cyclotron heating. ATF device is scheduled to start operation in the fall of 1986. An overview of the ATF device is presented including details of the construction process envisioned

Effects of toroidal field ripple on injected deuterons in the FED device

International Nuclear Information System (INIS)

Fowler, R.H.; Rome, J.A.

1981-07-01

A Monte Carlo beam deposition and thermalization code is used to assess the effects of toroidal field (TF) ripple on injected fast deuterons in the Fusion Engineering Device (FED). The code uses realistic geometry for the beam, plasma equilibrium, TF ripple, and vacuum chamber. For injection at an angle of 35 0 (co) from perpendicular, no particles were ripple trapped and less than 1% of the injected power went to the wall and the limiter. However, due to the large amounts of computer time required by these programs, only 100 particles were followed in the rippled case and the results must be regarded as preliminary

Theoretical studies of turbulence and anomalous transport in toroidal confinement devices

International Nuclear Information System (INIS)

Terry, P.W.

1990-01-01

The research performed under this grant during the current year has focused on key issues with respect to turbulence and transport in toroidal confinement devices. This work includes theoretical and computational studies of electron thermal confinement which have concentrated on the role of sheared poloidal flow in suppressing turbulence and transport, trapped ion convective cell turbulence and microtearing turbulence; analytical studies of anomalous particle transport and pinch mechanisms, and comparison with experimental measurement; development of the theory of self-consistent radial transport of field-aligned momentum in the tokamak and RFP; and work on other topics (ion temperature gradient driven turbulence, RFP fluctuation theory, coherent structures). Progress and publications in these areas are briefly summarized in this report. 20 refs

Pathway to a compact SASE FEL device

Science.gov (United States)

Dattoli, G.; Di Palma, E.; Petrillo, V.; Rau, Julietta V.; Sabia, E.; Spassovsky, I.; Biedron, S. G.; Einstein, J.; Milton, S. V.

2015-10-01

Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.

Pathway to a compact SASE FEL device

Energy Technology Data Exchange (ETDEWEB)

Dattoli, G., E-mail: giuseppe.dattoli@enea.it [ENEA – Centro Ricerche Frascati, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Di Palma, E. [ENEA – Centro Ricerche Frascati, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Petrillo, V. [Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Rau, Julietta V. [Istituto di Struttura della Materia, ISM-CNR, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Sabia, E.; Spassovsky, I. [ENEA – Centro Ricerche Frascati, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Biedron, S.G.; Einstein, J.; Milton, S.V. [CSU – Colorado State University, Fort Collins, CO (United States)

2015-10-21

Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.

Conceptual design of a cassette compact toroid reactor (the zero-phase study) - Quick replacement of the reactor core

International Nuclear Information System (INIS)

Nishikawa, M.; Narikawa, T.; Iwamoto, M.; Watanabe, K.

1986-01-01

A study of a conceptual design for a ''cassette'' compact toroid reactor has been performed that emphasizes quick replacement handling. The core plasma, spheromak, is ohmically heated in a merging process between the core plasma and the gun-produced spheromak. The quick handling of replacement accomplished by using a functional material, a shape memory alloy (SMA) joint, which is proposed for release from first-wall high neutron loading in a newly devised mechanical and structural method. The SMA joint can be used for connecting or disconnecting the coupling by simply controlling the SMA temperature without the need for a robot system. Effective heat removal from the first wall and thermal and electromagnetic stress in a fusion core with very high heat flux are discussed from an engineering standpoint

Compact torus theory: MHD equilibrium and stability

International Nuclear Information System (INIS)

Barnes, D.C.; Seyler, C.E.; Anderson, D.V.

1979-01-01

Field reversed theta pinches have demonstrated the production and confinement of compact toroidal configurations with surprisingly good MHD stability. In these observations, the plasma is either lost by diffusion or by the loss of the applied field or is disrupted by an n = 2 (where n is the toroidal mode number) rotating instability only after 30 to 100 MHD times, when the configuration begins to rotate rigidly above a critical speed. These experiments have led one to investigate the equilibrium, stability, and rotation of a very elongated, toroidally axisymmetric configuration with no toroidal field. Many of the above observations are explained by recent results of these investigations which are summarized

Overview of recent results and future plans on the Compact Toroidal Hybrid experiment

Science.gov (United States)

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

2015-11-01

Goals of the Compact Toroidal Hybrid (CTH) experiment are to: (1) investigate the dependence of plasma disruptive behavior on the level of applied 3D magnetic shaping, (2) test and advance 3D computational modeling tools in strongly shaped plasmas, and (3) study the implementation of a new island divertor. Progress towards these goals and other developments are summarized. The disruptive density limit is observed to exceed the Greenwald limit as the vacuum transform is increased, but a threshold for disruption avoidance is not observed. Low q operation is routine, with low q disruptions avoided when the vacuum transform is raised to the value of 0.07 or above. Application of vacuum transform has been demonstrated to reduce and eliminate the vertical drift of elongated discharges that would otherwise be vertically unstable. Current efforts at improved equilibrium reconstruction and diagnostic development will beoverviewed. NIMROD is used to model the current ramp phase of CTH and 3D shaped sawtooth behavior. An island divertor design has begun with connection length studies and initial EMC3-Eirene results to model energy deposition on divertor plates located in an edge 1/3 island. This work is supported by U.S. Department of Energy Grant No. DE- FG02-00ER54610.

Compact magnetic confinement fusion: Spherical torus and compact torus

Directory of Open Access Journals (Sweden)

Zhe Gao

2016-05-01

Full Text Available The spherical torus (ST and compact torus (CT are two kinds of alternative magnetic confinement fusion concepts with compact geometry. The ST is actually a sub-category of tokamak with a low aspect ratio; while the CT is a toroidal magnetic configuration with a simply-connected geometry including spheromak and field reversed pinch. The ST and CT have potential advantages for ultimate fusion reactor; while at present they can also provide unique fusion science and technology contributions for mainstream fusion research. However, some critical scientific and technology issues should be extensively investigated.

Heating in toroidal plasmas

International Nuclear Information System (INIS)

Knoepfel, H.; Mazzitelli, G.

1984-01-01

The article is a rather detailed report on the highlights in the area of the ''Heating in toroidal plasmas'', as derived from the presentations and discussions at the international symposium with the same name, held in Rome, March 1984. The symposium covered both the physics (experiments and theory) and technology of toroidal fusion plasma heating. Both large fusion devices (either already in operation or near completion) requiring auxiliary heating systems at the level of tens of megawatts, as well as physics of their heating processes and their induced side effects (as studied on smaller devices), received attention. Substantial progress was reported on the broad front of auxiliary plasma heating and Ohmic heating. The presentation of the main conclusions of the symposium is divided under the following topics: neutral-beam heating, Alfven wave heating, ion cyclotron heating, lower hybrid heating, RF current drive, electron cyclotron heating, Ohmic heating and special contributions

Compact reversed-field pinch reactors (CRFPR)

International Nuclear Information System (INIS)

Krakowski, R.A.; Miller, R.L.; Bathke, C.G.; Hagenson, R.L.; Copenhaver, C.; Werley, K.A.

1986-01-01

The unique confinement properties of the Reversed-Field Pinch (RFP) are exploited to examine physics and technical issues related to a compact, high-power-density fusion reactor. This resistive-coil, steady-state, toroidal device would use a dual-media power cycle driven by a fusion power core (FPC, i.e., plasma chamber, first wall, blanket, shield, and coils) with a power density and mass approaching values characteristic of pressurized-water fission rectors. A 1000-MWe(net) base case is selected from a comprehensive trade-off study to examine technological issues related to operating a high-power-density FPC. After describing the main physics and technology issues for this base-case reactor, directions for future study are suggested

OCLATOR (One Coil Low Aspect Toroidal Reactor)

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, S.

1980-02-01

A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the ..beta.. limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR (One Coil Low Aspect Toroidal Reactor).

Compact-toroid fusion reactor based on the field-reversed theta pinch: reactor scaling and optimization for CTOR

International Nuclear Information System (INIS)

Hagenson, R.L.; Krakowski, R.A.

1980-01-01

Early scoping studies based on approximate, analytic models have been extended on the basis of a dynamic plasma model and an overall systems approach to examine a Compact Toroid (CT) reactor embodiment that uses a Field-Reversed Theta Pinch as a plasma source. The field-reversed plasmoid would be formed and compressionally heated to ignition prior to injection into and translation through a linear burn chamber, thereby removing the high-technology plasmoid source from the hostile reactor environment. Stabilization of the field-reversed plasmoid would be provided by a passive conduction shell located outside the high-temperature blanket but within the low-field superconducting magnets and associated radiation shielding. On the basis of this batch-burn but thermally steady-state approach a reactor concept emerges with a length below approx. 40 m that generates 300 to 400 MWe of net electrical power with a recirculating power fraction less than 0.15

Toroidal simulation magnet tests

International Nuclear Information System (INIS)

Walstrom, P.L.; Domm, T.C.

1975-01-01

A number of different schemes for testing superconducting coils in a simulated tokamak environment are analyzed for their merits relative to a set of test criteria. Two of the concepts are examined in more detail: the so-called cluster test scheme, which employs two large background field coils, one on either side of the test coil, and the compact torus, a low-aspect ratio toroidal array of a small number of coils in which all of the coils are essentially test coils. Simulation of the pulsed fields of the tokamak is discussed briefly

Collapse analysis of toroidal shell

International Nuclear Information System (INIS)

Pomares, R.J.

1990-01-01

This paper describes a study performed to determine the collapse characteristics of a toroidal shell using finite element method (FEM) analysis. The study also included free drop testing of a quarter scale prototype to verify the analytical results. The full sized toroidal shell has a 24-inch toroidal diameter with a 24-inch tubal diameter. The shell material is type 304 strainless steel. The toroidal shell is part of the GE Model 2000 transportation packaging, and acts as an energy absorbing device. The analyses performed were on a full sized and quarter scaled models. The finite element program used in all analyses was the LIBRA code. The analytical procedure used both the elasto-plastic and large displacement options within the code. The loading applied in the analyses corresponded to an impact of an infinite rigid plane oriented normal to the drop direction vector. The application of the loading continued incrementally until the work performed by the deforming structure equalled the kinetic energy developed in the free fall. The comparison of analysis and test results showed a good correlation

Rotamak discharges in a 0.5 m diameter, spherical device

International Nuclear Information System (INIS)

Euripides, P.; Jones, I.R.; Deng Chuanbao

1997-01-01

In the rotamak concept, a rotating magnetic field is used to drive toroidal plasma current in a compact torus device in a non-inductive manner. The latest results from a 0.5 m diameter rotamak apparatus are presented. These show that, for a given filling pressure of hydrogen, it is possible to drive more current, whilst simultaneously preserving the compact torus configuration, by increasing the amount of RF power transferred to the plasma. Attention is drawn to the fact that a fair evaluation of the rotamak concept requires experimentation at higher RF power levels than are presently available. (author). Letter-to-the-editor

Program for development of toroidal superconducting magnets for fusion research, May 1975

International Nuclear Information System (INIS)

Long, H.M.; Lubell, M.S.

1975-11-01

The objective of this program is a tested magnet design which demonstrates the suitability and reliability needed to qualify toroidal superconducting magnets for fusion research devices in a time compatible with the D-T burning experiments time frame. The overall applied development program including tasks, manpower, and cost estimates is detailed here, but for the full toroidal system only the cost and time frame are outlined to show compatibility with the present program. The details of the full toroidal system fall under major device fabrication and will be included in a subsequent document

Numerical determination of axisymmetric toroidal magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Johnson, J.L.; Dalhed, H.E.; Greene, J.M.

1978-07-01

Numerical schemes for the determination of stationary axisymmetric toroidal equilibria appropriate for modeling real experimental devices are given. Iterative schemes are used to solve the elliptic nonlinear partial differential equation for the poloidal flux function psi. The principal emphasis is on solving the free boundary (plasma-vacuum interface) equilibrium problem where external current-carrying toroidal coils support the plasma column, but fixed boundary (e.g., conducting shell) cases are also included. The toroidal current distribution is given by specifying the pressure and either the poloidal current or the safety factor profiles as functions of psi. Examples of the application of the codes to tokamak design at PPPL are given

Compact tokamak reactors

International Nuclear Information System (INIS)

Wootton, A.J.; Wiley, J.C.; Edmonds, P.H.; Ross, D.W.

1997-01-01

The possible use of tokamaks for thermonuclear power plants is discussed, in particular tokamaks with low aspect ratio and copper toroidal field coils. Three approaches are presented. First, the existing literature is reviewed and summarized. Second, using simple analytic estimates, the size of the smallest tokamak to produce an ignited plasma is derived. This steady state energy balance analysis is then extended to determine the smallest tokamaks power plant, by including the power required to drive the toroidal field and by considering two extremes of plasma current drive efficiency. Third, the analytic results are augmented by a numerical calculation that permits arbitrary plasma current drive efficiency and different confinement scaling relationships. Throughout, the importance of various restrictions is emphasized, in particular plasma current drive efficiency, plasma confinement, plasma safety factor, plasma elongation, plasma beta, neutron wall loading, blanket availability and recirculation of electric power. The latest published reactor studies show little advantage in using low aspect ratios to obtain a more compact device (and a low cost of electricity) unless either remarkably high efficiency plasma current drive and low safety factor are combined, or unless confinement (the H factor), the permissible elongation and the permissible neutron wall loading increase as the aspect ratio is reduced. These results are reproduced with the analytic model. (author). 22 refs, 3 figs

Experimental demonstration of subwavelength domino plasmon devices for compact high-frequency circuit.

Science.gov (United States)

Ma, Y G; Lan, L; Zhong, S M; Ong, C K

2011-10-24

In optical frequency, surface plasmons of metal provide us a prominent way to build compact photonic devices or circuits with non-diffraction limit. It is attributed by their extraordinary electromagnetic confining effect. But in the counterpart of lower frequencies, plasmonics behavior of metal is screened by eddy current induced in a certain skin depth. To amend this, spoof plasmons engineered by artificial structures have been introduced to mimic surface plasmons in these frequencies. But it is less useful for practical application due to their weak field confinement as manifested by large field decaying length in the upper dielectric space. Recently, a new type of engineered plasmons, domino plasmon was theoretically proposed to produce unusual field confinement and waveguiding capabilities that make them very attractive for ultra-compact device applications [Opt. Exp. 18, 754-764 (2010)]. In this work, we implemented these ideas and built three waveguiding devices based on domino plasmons. Their strong capabilities to produce versatile and ultra-compact devices with multiple electromagnetic functions have been experimentally verified in microwaves. And that can be extended to THz regime to pave the way for a new class of integrated wave circuits. © 2011 Optical Society of America

Theoretical studies of turbulence and anomalous transport in toroidal confinement devices

International Nuclear Information System (INIS)

Terry, P.W.

1993-01-01

The research performed under this grant has focused on key issues with respect to turbulence and transport in toroidal confinement devices. Progress and publications in these areas are summarized in this report. This work includes analytical and numerical studies of spectral energy transfer and the saturation dynamics and transport of dissipative and collisionless trapped electron turbulence, the role of flow curvature in L-H mode transition physics, fully nonlinear calculations of the anomalous particle transport from the ion mixing mode, and the development of a theory for the drift wave frequency spectrum. Novel aspects of this work include an elucidation of the role of nonlinear frequency shifts in producing nonstationary saturated states, an identification of reverse and non-conserved flows in Hasegawa-Mima turbulence, and a description of the way incoherent emission affects the frequency of turbulent fluctuations

OCLATOR (One Coil Low Aspect Toroidal Reactor)

International Nuclear Information System (INIS)

Yoshikawa, S.

1980-02-01

A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the β limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR

Regimes of pulsed formation of a compact plasma configuration with a high energy input

Energy Technology Data Exchange (ETDEWEB)

Romadanov, I. V.; Ryzhkov, S. V., E-mail: svryzhkov@bmstu.ru [Bauman Moscow State Technical University (Russian Federation)

2015-10-15

Results of experiments on the formation of a compact toroidal magnetic configuration at the Compact Toroid Challenge setup are presented. The experiments were primarily aimed at studying particular formation stages. Two series of experiments, with and without an auxiliary capacitor bank, were conducted. The magnetic field was measured, its time evolution and spatial distribution over the chamber volume were determined, and its influence on the formation regimes was investigated.

Compact reversed-field pinch reactors (CRFPR)

International Nuclear Information System (INIS)

Krakowski, R.A.; Hagenson, R.L.; Schnurr, N.M.; Copenhaver, C.; Bathke, C.G.; Miller, R.L.; Embrechts, M.J.

1986-01-01

The unique confinement properties of the poloidal-field-dominated Reversed-Field Pinch (RFP) are exploited to examine physics and technical issues related to a compact high-power-density fusion reactor. This resistive-coil, steady-state, toroidal device would use a dual-media (i.e., two separate coolants) power cycle that would be driven by a fusion power core (FPC, i.e., plasma chamber, first wall, blanket, shield, and coils) having a power density and mass approaching pressurized-water-fission reactor values. A 1000-MWe(net) base case is selected from a comprehensive trade-off study to examine technological issues related to operating a high-power-density FPC. A general rationale outlining the need for improved fusion concepts is given, followed by a description of the RFP principle, a detailed systems and trade-off analysis, and a conceptual FPC design for the ∝ 20-MW/m 2 (neutrons) compact RFP reactor, CRFPR(20). Key FPC components are quantified, and full power-balance, thermal, and mechanical FPC integrations are given. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-08-19

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

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Poloidal variations in toroidal fusion reactor wall power loadings

International Nuclear Information System (INIS)

Carroll, M.C.; Miley, G.H.

1985-01-01

A geometric formulation is developed by the authors for determining poloidal variations in bremmstrahlung, cyclotron radiation, and neutron wall power loadings in toroidal fusion devices. Assuming toroidal symmetry and utilizing a numerical model which partitions the plasma into small cells, it was generally found that power loadings are highest on the outer surface of the torus, although variations are not as large as some have predicted. Results are presented for various plasma power generation configurations, plasma volume fractions, and toroidal aspect ratios, and include plasma and wall blockage effects

Compact torus equilibria set up in the rotamak by rotating magnetic fields

International Nuclear Information System (INIS)

Storer, R.G.

1983-01-01

In the Rotamak, a rotating magnetic field is used to drive a steady toroidal current in a compact torus device. High power, short duration (approx.=80 μs) and low power, long duration experiments (approx.=3 ms) have been studied. In both of these experiments a steady phase exists which is well described by the assumption that the plasma is in an averaged magnetohydrodynamic pressure balance situation. Using a model based on this assumption, self-consistency imposes conditions relating the temperature and density of the plasma to the steady components of the internal magnetic fields. In the high power experiment, this steady phase evolves into a second steady phase, with lower toroidal current, which has a #betta#=1, mirror-like configuration which also appears to satisfy local pressure balance but with the magnetic axis (minimum of the poloidal flux) at the centre of the spherical vessel. (orig.)

Fast mega pixels video imaging of a toroidal plasma in KT5D device

International Nuclear Information System (INIS)

Xu Min; Wang Zhijiang; Lu Ronghua; Sun Xiang; Wen Yizhi; Yu Changxuan; Wan Shude; Liu Wandong; Wang Jun; Xiao Delong; Yu Yi; Zhu Zhenghua; Hu Linyin

2005-01-01

A direct imaging system, viewing visible light emission from plasmas tangentially or perpendicularly, has been set up on the KT5D toroidal device to monitor the real two-dimensional profiles of purely ECR generated plasmas. This system has a typical spatial resolution of 0.2 mm (1280x1024 pixels) when imaging the whole cross section. Interesting features of ECR plasmas have been found. Different from what classical theories have expected, a resonance layer with two or three bright spots, rather than an even vertical band, has been observed. In addition, images also indicate an intermittent splitting and drifting character of the plasmas

Turbulent and neoclassical toroidal momentum transport in tokamak plasmas

International Nuclear Information System (INIS)

Abiteboul, J.

2012-10-01

The goal of magnetic confinement devices such as tokamaks is to produce energy from nuclear fusion reactions in plasmas at low densities and high temperatures. Experimentally, toroidal flows have been found to significantly improve the energy confinement, and therefore the performance of the machine. As extrinsic momentum sources will be limited in future fusion devices such as ITER, an understanding of the physics of toroidal momentum transport and the generation of intrinsic toroidal rotation in tokamaks would be an important step in order to predict the rotation profile in experiments. Among the mechanisms expected to contribute to the generation of toroidal rotation is the transport of momentum by electrostatic turbulence, which governs heat transport in tokamaks. Due to the low collisionality of the plasma, kinetic modeling is mandatory for the study of tokamak turbulence. In principle, this implies the modeling of a six-dimensional distribution function representing the density of particles in position and velocity phase-space, which can be reduced to five dimensions when considering only frequencies below the particle cyclotron frequency. This approximation, relevant for the study of turbulence in tokamaks, leads to the so-called gyrokinetic model and brings the computational cost of the model within the presently available numerical resources. In this work, we study the transport of toroidal momentum in tokamaks in the framework of the gyrokinetic model. First, we show that this reduced model is indeed capable of accurately modeling momentum transport by deriving a local conservation equation of toroidal momentum, and verifying it numerically with the gyrokinetic code GYSELA. Secondly, we show how electrostatic turbulence can break the axisymmetry and generate toroidal rotation, while a strong link between turbulent heat and momentum transport is identified, as both exhibit the same large-scale avalanche-like events. The dynamics of turbulent transport are

Formation of compact toroidal plasmas by magnetized coaxial plasma gun injection into an oblate flux conserver

International Nuclear Information System (INIS)

Turner, W.C.; Goldenbaum, G.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Smith, A.C. Jr.

1980-01-01

Initial results are reported on the formation of compact toroidal plasmas in an oblate shaped metallic flux conserver. A schematic of the experimental apparatus is shown. The plasma injector is a coaxial plasma gun with solenoid coils wound on the inner and outer electrodes. The electrode length is 100 cm, the diameter of the inner (outer) electrode is 19.3 cm (32.4 cm). Deuterium gas is puffed into the region between electrodes by eight pulsed valves located on the outer electrode 50 cm from the end of the gun. The gun injects into a cylindrically symmetrical copper shell (wall thickness = 1.6 mm) which acts as a flux conserver for the time scale of experiments reported here. The copper shell consists of a transition cylinder 30 cm long, 34 cm in diameter, a cylindrical oblate pill box 40 cm long, 75 cm in diameter and a downstream cylinder 30 cm long, 30 cm in diameter. The gap between the gun and transition cylinder is 6 cm. An axial array of coils outside the vacuum chamber can be used to establish an initial uniform bias field

Helical-tokamak hybridization concepts for compact configuration exploration and MHD stabilization

International Nuclear Information System (INIS)

Oishi, T.; Yamazaki, K.; Arimoto, H.; Baba, K.; Hasegawa, M.; Ozeki, H.; Shoji, T.; Mikhailov, M.I.

2010-11-01

To search for low-aspect-ratio torus systems, a lot of exotic confinement concepts are proposed so far historically. One of the authors previously proposed the tokamak-helical hybrid called TOKASTAR (Tokamak-Stellarator Hybrid) to improve the magnetic local shear near the bad curvature region. This is characterized by simple and compact coil systems with enough divertor space relevant to reactor designs. Based on this TOKASTAR concept, a toroidal mode number N=2 C (compact) -TOKASTAR machine (R - 35 mm) was constructed. The rotational transform of this compact helical configuration is rather small to confine hot ions, but can be utilized as a compact electron plasma machine for multi-purposes. The C-TOKASTAR has a pair of spherically winding helical coils and a pair of poloidal coils. Existence of magnetic surface and electron confinement property in C-TOKASTAR device were investigated by an electron-emission impedance method. Calculation of the particle orbit also supports that closed magnetic surface is formed in the cases that the ratio between poloidal and helical coil current is appropriate. Another aspect of the research using TOKASTAR configuration includes the evaluation of the effect of the outboard helical field application to tokamak plasmas. It is considered that outboard helical field has roles to assist the initiation of plasma current, to improve MHD stability, and so on. To check these roles, we made TOKASTAR-2 machine (R - 0.12 m, B - 1 kG) with ohmic heating central coil, eight toroidal field coils, a pair of vertical field coils and two outboard helical field coil segments. The electron cyclotron heating plasma start-up and plasma current disruption control experiments might be expected in this machine. Calculation of magnetic field line tracing has revealed that magnetic surface can be formed using additional outer helical coils. (author)

Stable confinement of toroidal electron plasma in an internal conductor device Prototype-Ring Trap

International Nuclear Information System (INIS)

Saitoh, H.; Yoshida, Z.; Watanabe, S.

2005-01-01

A pure electron plasma has been produced in an internal conductor device Prototype-Ring Trap (Proto-RT). The temporal evolution of the electron plasma was investigated by the measurement of electrostatic fluctuations. Stable confinement was realized when the potential profile adjusted to match the magnetic surfaces. The confinement time varies as a function of the magnetic field strength and the neutral gas pressure, and is comparable to the diffusion time of electrons determined by the classical collisions with neutral gas. Although the addition of a toroidal magnetic field stabilized the electrostatic fluctuation of the plasma, the effects of the magnetic shear shortened the stable confinement time, possibly because of the obstacles of coil support structures

A paramagnetic nearly isodynamic compact magnetic confinement system

International Nuclear Information System (INIS)

Cooper, W.A.; Antonietti, J.M.; Todd, T.N.

2001-01-01

A coreless compact magnetic confinement system that consists of sets of helical windings and vertical magnetic field coils is investigated. The helical coils produce a small toroidal translation of the magnetic field lines and seed paramagnetism. The force-free component of the toroidal current strongly enhances the paramagnetism such that isodynamic conditions near the plasma centre can be approached. At β 5%, the configuration is stable to local MHD modes. Global MHD modes limit the toroidal current 2πJ to about 60kA for peaked J. Bootstrap-like hollow current profiles generate quasiaxisymmetric systems that require a close fitting conducting shell to satisfy external kink stability. (author)

Theory of the rippling instability in toroidal devices

International Nuclear Information System (INIS)

Rogister, A.

1985-04-01

The theory of the rippling instability is developed for axisymmetric toroidal plasmas including ion viscosity and parallel electron heat conduction, but assuming that the growth rate is small compared to the wave angular frequency. Parallel electron heat conduction is stabilizing but ion viscosity broadens the instability domain. Under certain conditions, an important top-bottom asymmetry of the density fluctuation spectrum may arise. (orig./GG)

Observation of Fano resonance and classical analog of electromagnetically induced transparency in toroidal metamaterials

Energy Technology Data Exchange (ETDEWEB)

Han, Song; Yang, Helin [College of Physical Science and Technology, Central China Normal University, Wuhan (China); Cong, Lonqing; Singh, Ranjan [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Gao, Fei [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore)

2016-05-15

Toroidal multipoles have recently been explored in various scientific communities, ranging from atomic and molecular physics, electrodynamics, and solid-state physics to biology. Here we experimentally and numerically demonstrate a three-dimensional toroidal metamaterial where two different toroidal dipoles along orthogonal directions have been observed. The chosen toroidal metamaterial also simultaneously supports Fano resonance and the classical analog of electromagnetically induced transparency (EIT) phenomena in the transmission spectra that originate from the electric-toroidal dipole and electric-magnetic dipole destructive interference. The intriguing properties of the toroidal resonances may open up avenues for applications in toroidal moments generator, sensing and slow-light devices. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Technical use of compact micro-onde devices

International Nuclear Information System (INIS)

Sortais, P.; Lamy, T.; Medard, J.; Angot, J.; Sudraud, P.; Salord, O.; Homri, S.

2012-01-01

Due to the very small size of a COMIC (Compact MIcrowave and Coaxial) device [P. Sortais, T. Lamy, J. Medard, J. Angot, L. Latrasse, and T. Thuillier, Rev. Sci. Instrum. 81, 02B31 (2010)] it is possible to install such plasma or ion source inside very different technical environments. New applications of such a device are presented, mainly for industrial applications. We have now designed ion sources for highly focused ion beam devices, ion beam machining ion guns, or thin film deposition machines. We will mainly present new capabilities opened by the use of a multi-beam system for thin film deposition based on sputtering by medium energy ion beams. With the new concept of multi-beam sputtering (MBS), it is possible to open new possibilities concerning the ion beam sputtering (IBS) technology, especially for large size deposition of high uniformity thin films. By the use of multi-spots of evaporation, each one corresponding to an independent tuning of an individual COMIC ion source, it will be very easy to co-evaporate different components.

Technical use of compact micro-onde devices

Energy Technology Data Exchange (ETDEWEB)

Sortais, P.; Lamy, T.; Medard, J.; Angot, J. [Laboratoire de Physique Subatomique et de Cosmologie de Grenoble - UJF-CNRS/IN2P3 - INPG, 53, rue des Martyrs, 38026 Grenoble Cedex (France); Sudraud, P.; Salord, O.; Homri, S. [Orsay Physics S.A., 95 avenue des Monts Aureliens, F-13710 Fuveau (France)

2012-02-15

Due to the very small size of a COMIC (Compact MIcrowave and Coaxial) device [P. Sortais, T. Lamy, J. Medard, J. Angot, L. Latrasse, and T. Thuillier, Rev. Sci. Instrum. 81, 02B31 (2010)] it is possible to install such plasma or ion source inside very different technical environments. New applications of such a device are presented, mainly for industrial applications. We have now designed ion sources for highly focused ion beam devices, ion beam machining ion guns, or thin film deposition machines. We will mainly present new capabilities opened by the use of a multi-beam system for thin film deposition based on sputtering by medium energy ion beams. With the new concept of multi-beam sputtering (MBS), it is possible to open new possibilities concerning the ion beam sputtering (IBS) technology, especially for large size deposition of high uniformity thin films. By the use of multi-spots of evaporation, each one corresponding to an independent tuning of an individual COMIC ion source, it will be very easy to co-evaporate different components.

Thermonuclear device

International Nuclear Information System (INIS)

Tezuka, Masaru.

1993-01-01

Protrusions and recesses are formed to a vacuum vessel and toroidal magnetic coils, and they are engaged. Since the vacuum vessel is generally supported firmly by a rack or the like by support legs, the toroidal magnetic field coils can be certainly supported against tumbling force. Then, there can be attained strong supports for the toroidal magnetic field coils, in addition to support by wedges on the side of inboard and support by share panels on the side of outboard, capable of withstanding great electromagnetic forces which may occur in large-scaled next-generation devices. That is, toroidal magnetic field coils excellent from a view point of deformation and stress can be obtained, to provide a thermonuclear device of higher reliability. (N.H.)

Longitudinal permittivity of a toroidal plasma near rational surfaces

International Nuclear Information System (INIS)

Nekrasov, F.M.

1990-01-01

A quite simple analytical formula for longitudinal permittivity, suitable for numerical processing on a computer, is determined. On the basis of a Fourier representation a poloidal angle a compact expression for the imaginary part of longitudinal permittivity near rational surfaces (m+nq=0) at an arbitrary relation between the bounce frequency and excited wave frequency is determined. A strongly magnetized collisionless plasma in the weak toroidality approximation is considered

Design features of HTMR-hybrid toroidal magnet tokamak reactor

International Nuclear Information System (INIS)

Rosatelli, F.; Avanzini, P.G.; Derchi, D.; Magnasco, M.; Grattarola, M.; Peluffo, M.; Raia, G.; Brunelli, B.; Zampaglione, V.

1984-01-01

The HTMR (Hybrid Toroidal Magnet Tokamak Reactor) conceptual design is aimed to demonstrate the feasibility of a Tokamak reactor which could fulfil the scientific and technological objectives expected from next generation devices with size and costs as small as possible. A hybrid toroidal field magnet, made up by copper and superconducting coils, seems to be a promising solution, allowing a considerable flexibility in machine performances, so as to gain useful margins in front of the uncertainties in confinement time scaling laws and beta and plasma density limits. The optimization procedure for the hybrid magnet, configuration, the main design features of HTMR and the preliminary mechanical calculations of the superconducting toroidal coils are described. (author)

Structural analysis of TFTR toroidal field coil conceptual design

International Nuclear Information System (INIS)

Smith, R.A.

1975-10-01

The conceptual design evaluation of the V-shaped toroidal field coils on the Tokamak Fusion Test Reactor has been performed by detailed structural analysis with the finite element method. The innovation provided by this design and verified in this work is the capability to support toroidal field loads while simultaneously performing the function of twist restraint against the device axial torques resulting from the vertical field loads. The evaluations made for the conceptual design provide predictions for coil deflections and stresses. The results are available for the separate effects from toroidal fields, poloidal fields, and the thermal expansion of the coils as well as for the superposition of the primary loads and the primary plus thermal loads

Formation of compact toroidal configurations for magnetic confinement of high temperature plasmas

International Nuclear Information System (INIS)

Fuentes, N.O.; Rodrigo, A.B.

1986-01-01

The formation stage of inverted magnetic field toroidal configurations (FRC) for hot plasmas confinement using a low energy linear theta pinch is studied. The diagnostic techniques used are based on optical spectroscopy, ultrarapid photography, magnetic probes and excluded flux compensated bonds. The generalities of the present research program, the used diagnostic techniques and the results obtained are discussed. (Author)

Measurement of toroidal plasma current in RF heated helical plasmas

International Nuclear Information System (INIS)

Besshou, Sakae

1993-01-01

This report describes the measurement of toroidal plasma current by a semiflexible Rogowski coil in a helical vacuum chamber. A Rogowski coil measures the toroidal plasma current with a resolution of 0.1 kA, frequency range of up to 1 kHz and sensitivity of 6.5 x 10 -9 V · s/A. We measured the spontaneous toroidal plasma current (from -1.2 to +1.2 kA) under electron cyclotron resonance heating at 0.94 T toroidal field in the Heliotron-E device. We found that the measured direction of toroidal plasma current changes its sign as in the predicted behavior of a neoclassical diffusion-driven bootstrap current, depending on the horizontal position of the plasma column. We explain the observed plasma currents in terms of the compound phenomenon of an ohmic current and a neoclassical diffusion-driven current. The magnitude of the neoclassical current component is smaller than the value predicted by a collisionless neoclassical theory. (author)

Modal analysis of a stiffened toroidal shell sector

International Nuclear Information System (INIS)

Cerreta, R.; Di Pietro, E.; Pizzuto, A.

1987-01-01

This paper presents the results of the modal analysis of a sector of the toroidal vacuum vessel of a new experimental machine for research in the field of controlled thermonuclear fusion (FTU - Frascati Tokamak Upgrade). The vacuum vessel, one of the most critical components of the experimental device, consist of 12 stainless steel toroidal sectors, and it is designed to withstand pulsed electromagnetic loads during operation. Results of the modal analysis of the stiffened toroidal shell sector are compared and discussed with regard to the experimental data. Theoretical eigenvalues and eigenvectors have been predicted by means of ABAQUS finite element code. Experimental analysis has been carried out on a full scale model and natural frequencies have been measured. Satisfactory agreement between experimental and theoretical eigenvalues has been found

Design features of HTMR-Hybrid Toroidal Magnet Tokamak Reactor

International Nuclear Information System (INIS)

Rosatelli, F.; Avanzini, P.G.; Brunelli, B.; Derchi, D.; Magnasco, M.; Grattarola, M.; Peluffo, M.; Raia, G.; Zampaglione, V.

1985-01-01

The HTMR (Hybrid Toroidal Magnet Tokamak Reactor) conceptual design is aimed to demonstrate the feasibility of a Tokamak reactor which could fulfill the scientific and technological objectives expected from next generation devices (e.g. INTOR-NET) with size and costs as small as possible. An hybrid toroidal field magnet, made up by copper and superconducting coils, seems to be a promising solution, allowing a considerable flexibility in machine performances, so as to gain useful margins in front of the uncertainties in confinement time scaling laws and beta and plasma density limits. In this paper the authors describe the optimization procedure for the hybrid magnet configuration, the main design features of HTMR and the preliminary mechanical calculations of the superconducting toroidal coils

Observation of plasma toroidal-momentum dissipation by neoclassical toroidal viscosity.

Science.gov (United States)

Zhu, W; Sabbagh, S A; Bell, R E; Bialek, J M; Bell, M G; LeBlanc, B P; Kaye, S M; Levinton, F M; Menard, J E; Shaing, K C; Sontag, A C; Yuh, H

2006-06-09

Dissipation of plasma toroidal angular momentum is observed in the National Spherical Torus Experiment due to applied nonaxisymmetric magnetic fields and their plasma-induced increase by resonant field amplification and resistive wall mode destabilization. The measured decrease of the plasma toroidal angular momentum profile is compared to calculations of nonresonant drag torque based on the theory of neoclassical toroidal viscosity. Quantitative agreement between experiment and theory is found when the effect of toroidally trapped particles is included.

The control system of the RFX toroidal power supply

International Nuclear Information System (INIS)

Toigo, V.; Piovan, R.; Zanotto, L.; Perna, M.; Coffetti, A.; Freghieri, M.; Povolero, M.

2005-01-01

This paper describes the control system of the toroidal power supply of the RFX experiment and outlines its specific hardware and software structure, which allowed to cope with the numerous requirements of the application with a compact hardware arrangement. The active fault protection strategies, implemented in the control system, are also discussed; finally, a special part of the control, which greatly simplified the long and complex commissioning of the power section of the system, is described

A method for external measurement of toroidal equilibrium parameters

International Nuclear Information System (INIS)

Brunsell, P.; Hellblom, G.; Brynolf, J.

1992-01-01

A method has been developed for determining from external magnetic field measurements the horizontal shift, the vertical shift and the poloidal field asymmetry parameter (Λ) of a toroidal plasma in force equilibrium. The magnetic measurements consist of two toroidal differential flux loops, giving the average vertical magnetic field and the average radial magnetic field respectively, together with cosine-coils for obtaining the m=1 cosine harmonic of the external poloidal magnetic field component. The method is used to analyse the evolution of the toroidal equilibrium during reversed-field pinch discharges in the Extrap T1-U device. We find that good equilibrium control is needed for long plasma pulses. For non-optimized externally applied vertical fields, the diagnostic clearly shows a horizontal drift motion of the pinch resulting in earlier discharge termination. (au)

Computational physics program of the National MFE Computer Center

International Nuclear Information System (INIS)

Mirin, A.A.

1985-12-01

The development of numerical models for plasma phenomena and magnetic confinement devices is discussed. The multidimensional Fokker-Planck and transport codes are applied to toroidal mirror and compact toroid devices. Linear and nonlinear resistive magnetohydrodynamics in two and three dimensions are used in the investigation of various fusion devices. 362 refs., 4 tabs

Magnetic divertor design for the compact reversed-field pinch reactor

International Nuclear Information System (INIS)

Bathke, C.G.; Miller, R.L.; Krakowski, R.A.

1984-01-01

A recently completed design of a pumped-limiter-based Compact Reversed-Field Pinch Reactor is used to estimate for the first time the impact of magnetic divertors. A range of divertor options for the low-toroidal-field RFP is examined, and a design selection is made constrained by consideration of field ripple (magnetic island), blanket displacement, recirculating power, cost, heat flux, and access. Design choices based on diversion of minority (toroidal) field lead to a preference for (poloidally) symmetric or bundle divertor geometries

Transport in the high temperature core of toroidal confinement systems

International Nuclear Information System (INIS)

Weiland, J.

1994-01-01

Recent theoretical and experimental results on confinement of hot plasmas in toroidal devices, particularly tokamaks, are discussed from general principal points of view and related to predictions from a toroidal drift wave model using a full transport matrix including off diagonal terms. A reactive fluid model corresponding to a two pole approximation of the kinetic response is used. This model has the ability to reproduce both adiabatic and isothermal limits of the perpendicular dynamics. 106 refs, 8 figs, 1 tab

Fast-ion transport during repetitive burst phenomena of toroidal Alfven eigenmodes in the Large Helical Device

International Nuclear Information System (INIS)

Nishiura, M.; Isobe, M.; Yamamoto, S.

2008-10-01

Alfven instabilities induced fast-ion losses have been directly observed for the first time by a newly developed scintillator lost ion probe (SLIP) in the Large Helical Device (LHD). The SLIP can measure the pitch angle and gyro radius of escaped fast ions toward loss region. Neutral beam driven Alfven Eigenmodes (AEs) are excited under the reactor relevant conditions: the ratio of fast ion (beam) speed υ b and Alfven speed υ A is more than 0.3 - 4.0. The beta value for fast ions is considered roughly to be ∼10%. Non-linear phenomena related to Alfven instabilities are observed under such conditions. During repetitive Toroidal Alfven Eigenmode (TAE) bursts, synchronized fast ion losses are observed by SLIP. From the orbit calculation the measured fast ion with pitch angle of 130 degrees and beam energy of 150 keV surely pass through the locations of TAE gaps. The orbit analysis found that the observed fast ions interact strongly with the excited TAEs. This result becomes the first experimental evidence of radial transport of fast ions predicted theoretically during TAE activities. In addition, from the correlation between stored energy degradation and fast-ion loss rate, it is found that fast-ion losses induced by TAE activities with low toroidal mode numbers categorize two phenomena without and with fast- ion loss enhancements, which indicate the fast-ion redistribution and loss. (author)

Ion temperature gradient modes in toroidal helical systems

Energy Technology Data Exchange (ETDEWEB)

Kuroda, T. [Graduate University for Advanced Studies, Toki, Gifu (Japan); Sugama, H.; Kanno, R.; Okamoto, M.

2000-04-01

Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of {nabla}B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)

Ion temperature gradient modes in toroidal helical systems

International Nuclear Information System (INIS)

Kuroda, T.; Sugama, H.; Kanno, R.; Okamoto, M.

2000-04-01

Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of ∇B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)

Compact and tunable focusing device for plasma wakefield acceleration

Science.gov (United States)

Pompili, R.; Anania, M. P.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Lollo, V.; Notargiacomo, A.; Picardi, L.; Ronsivalle, C.; Rosenzweig, J. B.; Shpakov, V.; Vannozzi, A.

2018-03-01

Plasma wakefield acceleration, either driven by ultra-short laser pulses or electron bunches, represents one of the most promising techniques able to overcome the limits of conventional RF technology and allows the development of compact accelerators. In the particle beam-driven scenario, ultra-short bunches with tiny spot sizes are required to enhance the accelerating gradient and preserve the emittance and energy spread of the accelerated bunch. To achieve such tight transverse beam sizes, a focusing system with short focal length is mandatory. Here we discuss the development of a compact and tunable system consisting of three small-bore permanent-magnet quadrupoles with 520 T/m field gradient. The device has been designed in view of the plasma acceleration experiments planned at the SPARC_LAB test-facility. Being the field gradient fixed, the focusing is adjusted by tuning the relative position of the three magnets with nanometer resolution. Details about its magnetic design, beam-dynamics simulations, and preliminary results are examined in the paper.

Moving toroidal limiter

International Nuclear Information System (INIS)

Ikuta, Kazunari; Miyahara, Akira.

1983-06-01

The concept of the limiter-divertor proposed by Mirnov is extended to a toroidal limiter-divertor (which we call moving toroidal limiter) using the stream of ferromagnetic balls coated with a low Z materials such as plastics, graphite and ceramics. An important advantage of the use of the ferromagnetic materials would be possible soft landing of the balls on a catcher, provided that the temperature of the balls is below Curie point. Moreover, moving toroidal limiter would work as a protector of the first wall not only against the vertical movement of plasma ring but also against the violent inward motion driven by major disruption because the orbit of the ball in the case of moving toroidal limiter distributes over the small major radius side of the toroidal plasma. (author)

Toroidally symmetric/asymmetric effect on the divertor flux due to neon/nitrogen seeding in LHD

Directory of Open Access Journals (Sweden)

H. Tanaka

2017-08-01

Full Text Available Toroidal distributions of divertor particle flux during neon (Ne and nitrogen (N2 seeded discharges were investigated in the Large Helical Device (LHD. By using 14 toroidally distributed divertor probe arrays, which were positioned at radially inner side where the divertor flux concentrates in the inward-shifted magnetic axis configuration, it is found that Ne puffing leads to toroidally quasi-uniform reduction of divertor particle fluxes; whereas toroidally localized reductions were observed with N2 puffing. The toroidally asymmetric reduction pattern with N2 puffing is strongly related to the magnetic field structure around the N2 puffing port. Assuming that nitrogen particles do not recycle, EMC3-EIRENE simulation shows similar reduction pattern with the experiment around the N2 puffing port.

Compact plane illumination plugin device to enable light sheet fluorescence imaging of multi-cellular organisms on an inverted wide-field microscope

OpenAIRE

Guan, Zeyi; Lee, Juhyun; Jiang, Hao; Dong, Siyan; Jen, Nelson; Hsiai, Tzung; Ho, Chih-Ming; Fei, Peng

2015-01-01

We developed a compact plane illumination plugin (PIP) device which enabled plane illumination and light sheet fluorescence imaging on a conventional inverted microscope. The PIP device allowed the integration of microscope with tunable laser sheet profile, fast image acquisition, and 3-D scanning. The device is both compact, measuring approximately 15 by 5 by 5 cm, and cost-effective, since we employed consumer electronics and an inexpensive device molding method. We demonstrated that PIP pr...

New Toroid shielding design

CERN Multimedia

Hedberg V

On the 15th of June 2001 the EB approved a new conceptual design for the toroid shield. In the old design, shown in the left part of the figure above, the moderator part of the shielding (JTV) was situated both in the warm and cold areas of the forward toroid. It consisted both of rings of polyethylene and hundreds of blocks of polyethylene (or an epoxy resin) inside the toroid vacuum vessel. In the new design, shown to the right in the figure above, only the rings remain inside the toroid. To compensate for the loss of moderator in the toroid, the copper plug (JTT) has been reduced in radius so that a layer of borated polyethylene can be placed around it (see figure below). The new design gives significant cost-savings and is easier to produce in the tight time schedule of the forward toroid. Since the amount of copper is reduced the weight that has to be carried by the toroid is also reduced. Outgassing into the toroid vacuum was a potential problem in the old design and this is now avoided. The main ...

Samus Toroid Installation Fixture

Energy Technology Data Exchange (ETDEWEB)

Stredde, H.; /Fermilab

1990-06-27

The SAMUS (Small Angle Muon System) toroids have been designed and fabricated in the USSR and delivered to D0 ready for installation into the D0 detector. These toroids will be installed into the aperture of the EF's (End Toroids). The aperture in the EF's is 72-inch vertically and 66-inch horizontally. The Samus toroid is 70-inch vertically by 64-inch horizontally by 66-inch long and weighs approximately 38 tons. The Samus toroid has a 20-inch by 20-inch aperture in the center and it is through this aperture that the lift fixture must fit. The toroid must be 'threaded' through the EF aperture. Further, the Samus toroid coils are wound about the vertical portion of the aperture and thus limit the area where a lift fixture can make contact and not damage the coils. The fixture is designed to lift along a surface adjacent to the coils, but with clearance to the coil and with contact to the upper steel block of the toroid. The lift and installation will be done with the 50 ton crane at DO. The fixture was tested by lifting the Samus Toroid 2-inch off the floor and holding the weight for 10 minutes. Deflection was as predicted by the design calculations. Enclosed are sketches of the fixture and it relation to both Toroids (Samus and EF), along with hand calculations and an Finite Element Analysis. The PEA work was done by Kay Weber of the Accelerator Engineering Department.

Plasma engineering assessments of compact ignition experiments

International Nuclear Information System (INIS)

Houlberg, W.A.

1985-01-01

Confinement, startup sequences, and fast-alpha particle effects are assessed for a class of compact tokamak ignition experiments having high toroidal magnetic fields (8 to 12 T) and high toroidal currents (7 to 10 MA). The uncertainties in confinement scaling are spanned through examples of performance with an optimistic model based on ohmically heated plasmas and a pessimistic model that includes confinement degradation by both auxiliary and alpha heating. The roles of neoclassical resistivity enhancement and sawtooth behavior are also evaluated. Copper toroidal field coils place restrictions on pulse lengths due to resistive heating, so a simultaneous rampup of the toroidal field and plasma current is proposed as a means of compressing the startup phase and lengthening the burn phase. If the ignition window is small, fast-alpha particle physics is restricted to the high-density regime where a short slowing-down time leads to low fast-particle density and pressure contributions. Under more optimistic confinement, a larger ignition margin broadens the range of alpha particle physics that can be addressed. These issues are illustrated through examples of transport simulations for a set of machine parameters called BRAND-X, which typify the designs under study

Plasma engineering assessments of compact ignition experiments

International Nuclear Information System (INIS)

Houlberg, W.A.

1986-01-01

Confinement, startup sequences, and fast-alpha particle effects are assessed for a class of compact tokamak ignition experiments having high toroidal magnetic fields (8-12 T) and high toroidal currents (7-10 MA). The uncertainties in confinement scaling are spanned through examples of performance with an optimistic model based on ohmically heated plasmas and a pessimistic model that includes confinement degradation by both auxiliary and alpha heating. The roles of neoclassical resistivity enhancement and sawtooth behavior are also evaluated. Copper toroidal field coils place restrictions on pulse lengths due to resistive heating, so a simultaneous rampup of the toroidal field and plasma current is proposed as a means of compressing the startup phase and lengthening the burn phase. If the ignition window is small, fast-alpha particle physics is restricted to the high-density regime where a short slowing-down time leads to low fast-particle density and pressure contributions. Under more optimistic confinement, a larger ignition margin broadens the range of alpha particle physics that can be addressed. These issues are illustrated through examples of transport simulations for a set of machine parameters called BRAND-X, which typify the designs under study

Runaway electrons in toroidal discharges

International Nuclear Information System (INIS)

Knoepfel, H.

1979-01-01

Experimental and theoretical studies of runaway electrons in toroidal devices are reviewed here, with particular reference to tokamaks. The complex phenomenology of runaway effects, which have been the subject of research for the past twenty years, is organized within the framework of a number of physical models. The mechanisms and rates for runaway production are discussed first, followed by sections on runaway-driven kinetic relaxation processes and runaway orbit confinement. Next, the equilibrium and stability of runaway-dominated discharges are reviewed. Models for runaway production at early times in the discharge and the scaling of runaway phenomena to larger devices are also discussed. Finally, detection techniques and possible applications of runaways are mentioned. (author)

Qualifying tests for TRIAM-1M superconducting toroidal magnetic field coil

Energy Technology Data Exchange (ETDEWEB)

Nakanura, Yukio; Hiraki, Naoji; Nakamura, Kazuo; Tanaka, Masayoshi; Nagao, Akihiro; Kawasaki, Shoji; Itoh, Satoshi

1984-09-01

In the strong toroidal magnetic field experimental facility ''TRIAM-1M'' currently under construction, construction of the superconducting toroidal magnetic field coil and the following qualifying tests conducted on the full-scale superconducting toroidal magnetic field coil actually fabricated are described: (1) coil excitation test, (2) superconducting stability test, (3) external magnetic field application test, and (4) high-speed excitation test. On the basis of these test results, stability was evaluated of the superconducting coil being operated in the tokamak device. In normal tokamak operation, there occurs no normal conduction transition. At the time of plasma disruption, though this transition takes place in part of the coil, the superconducting state is immediately restored. By its electromagnetic force analysis, the superconducting coil is also stable in structure.

Position indicating split toroid for the RACE experiment

International Nuclear Information System (INIS)

Hurst, B.; Folkman, K.

2007-01-01

Aspects of the recent reactor accelerator coupled experiments (RACE) carried out at 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

Novel configuration for an enhanced and compact all-fiber Faraday rotator with matched birefringence.

Science.gov (United States)

Asraf, Sagie; Sintov, Yoav; Zalevsky, Zeev

2017-08-07

We propose a novel configuration for an improved and compact all fiber Faraday rotator based on phase matching between the Faraday rotation and bend-induced birefringence. The device utilizes a coiled fiber within two electro-magnetic toroids, such that the fiber length required for getting the beat length is quite long and several rounds of fiber are needed. Analysis of the capabilities of the proposed device and its sensitivity to different parameters is presented. Faraday rotation of 13° was experimentally measured in six meters of single mode silica fiber, with a magnetic field of about 0.06T at a wavelength of 1064nm. We show that phase matching between the two phenomena significantly improves the polarization rotation by a factor of 4-10. In addition, we demonstrate the ability to achieve higher rotation by using Fabry Perot resonator in low terbium doped glass.

Structure of the radial electric field and toroidal/poloidal flow in high temperature toroidal plasma

International Nuclear Information System (INIS)

Ida, Katsumi

2001-01-01

The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in toroidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasma because of the helicity of symmetry of the magnetic field configuration. (author)

Insulation structure of thermonuclear device

International Nuclear Information System (INIS)

Suzuki, Takayuki; Usami, Saburo; Tsukamoto, Hideo; Kikuchi, Mitsuru

1998-01-01

The present invention provides an insulating structure of a thermonuclear device, in which insulation materials between toroidal coils are not broken even if superconductive toroidal coils are used. Namely, a tokamak type thermonuclear device of an insulating structure type comprises superconductive toroidal coils for confining plasmas arranged in a circular shape directing the center each at a predetermined angle, and the toroidal coils are insulated from each other. The insulation materials are formed by using a biaxially oriented fiber reinforced plastics. The contact surface of the toroidal coils and the insulating materials are arranged so that they are contact at a woven surface of the fiber reinforced plastics. Either or both of the contact surfaces of the fiber reinforced plastics and the toroidal coils are coated with a high molecular compound having a low friction coefficient. With such a constitution, since the interlayer shearing strength of the biaxially oriented fiber reinforced plastics is about 1/10 of the compression strength, the shearing stress exerted on the insulation material is reduced. Since a static friction coefficient on the contact surface is reduced to provide a structure causing slipping, shearing stress does not exceeds a predetermined limit. As a result, breakage of the insulation materials between the toroidal coils can be prevented. (I.S.)

Compact toroid formation using barrier fields and controlled reconnection in the TRX-1 field reversed theta pinch

International Nuclear Information System (INIS)

Hoffman, A.L.; Armstrong, W.T.

1982-01-01

TRX-1 is a new 20 cm diameter, 1-m long field reversed theta pinch with a magnetic field swing of 10 kG in 3 μsec. It employs z discharge preionization and octopole barrier fields to maximize flux trapping on first half cycle operation. Cusp coils are used at the theta pinch ends to delay reconnection and fast mirror coils are used to trigger reconnection at a time designed to maximize axial heating efficiency and toroid lifetime. These controls are designed to study toroid formation methods which are claimed to be especially efficient by Russian experimenters. Studies have been conducted on flux trapping efficiency, triggered reconnection, and equilibrium and lifetime

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

Energy Technology Data Exchange (ETDEWEB)

Hao, G. Z., E-mail: haogz@swip.ac.cn; Wang, A. K.; Xu, Y. H.; He, H. D.; Xu, M.; Qu, H. P.; Peng, X. D.; Xu, J. Q.; Qiu, X. M. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Sun, Y. [Institute of Plasma Physics, Chinese Academic of Sciences, P.O. Box 1126, Hefei 230031 (China); Cui, S. Y. [School of Mathematics and Statistics Science, Ludong University, Yantai 264025 (China)

2014-12-15

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

Ohmically heated toroidal experiment (OHTE) mobile ignition test reactor facility concept study

International Nuclear Information System (INIS)

Masson, L.S.; Watts, K.D.; Piscitella, R.R.; Sekot, J.P.; Drexler, R.L.

1983-02-01

This report presents the results of a study to evaluate the use of an existing nuclear test complex at the Idaho National Engineering Laboratory (INEL) for the assembly, testing, and remote maintenance of the ohmically heated toroidal experiment (OHTE) compact reactor. The portable reactor concept is described and its application to OHTE testing and maintenance requirements is developed. Pertinent INEL facilities are described and several test system configurations that apply to these facilities are developed and evaluated

Superconducting endcap toroid design report

Energy Technology Data Exchange (ETDEWEB)

Walters, C.R.; Baynham, D.E.; Holtom, E.; Coombs, R.C.

1992-10-01

The Atlas Experiment proposed for the LHC machine will use toroidal magnet systems to achieve high muon momentum resolutions. One of the options under consideration is an air cored superconducting toroidal magnet system consisting of a long barrel toroid with small and cap toroids inserted in it to provide high resolution at high pseudorapidity. The design of the barrel toroid has been studied over the past two years and the design outline is given in a Saclay Report. More recently consideration has been given to an end cap toroid system which is based on air cored superconducting coils. This report presents the basic engineering design of such a system, the proposals for fabrication, assembly and installation, and an outline cost estimate for one end cap is presented in Appendix 1.

Current generation by unidirectional lower hybrid waves in the ACT-1 toroidal device

International Nuclear Information System (INIS)

Wong, K.L.; Horton, R.; Ono, M.

1980-05-01

An unambiguious experimental observation of current generation by unidirectional lower hybrid waves in a toroidal plasma is reported. Up to 10 amperes of current was driven by 500 watts of rf power at 160 MHz

Compact and high-efficiency device for Raman scattering measurement using optical fibers.

Science.gov (United States)

Mitsui, Tadashi

2014-11-01

We describe the design and development of a high-efficiency optical measurement device for operation within the small bore of a high-power magnet at low temperature. For the high-efficiency measurement of light emitted from this small region, we designed a compact confocal optics with lens focusing and tilting systems, and used a piezodriven translation stage that allows micron-scale focus control of the sample position. We designed a measurement device that uses 10 m-long optical fibers in order to avoid the influence of mechanical vibration and magnetic field leakage of high-power magnets, and we also describe a technique for minimizing the fluorescence signal of optical fibers. The operation of the device was confirmed by Raman scattering measurements of monolayer graphene on quartz glass with a high signal-to-noise ratio.

Visible Spectrometer at the Compact Toroid Injection Experiment, the Sustained Spheromak Plasma Experiment and the Alcator C-Mod Tokamak for Doppler Width and Shift Measurements

Energy Technology Data Exchange (ETDEWEB)

Graf, A; Howard, S; Horton, R; Hwang, D; May, M; Beiersdorfer, P; McLean, H; Terry, J

2006-05-15

A novel Doppler spectrometer is currently being used for ion or neutral velocity and temperature measurements on the Alcator C-Mod Tokamak. The spectrometer has an f/No. of {approx}3.1 and is appropriate for visible light (3500-6700 {angstrom}). The full width at half maximum from a line emitting calibration source has been measured to be as small as 0.4 {angstrom}. The ultimate time resolution is line brightness light limited and on the order of ms. A new photon efficient detector is being used for the setup at C-Mod. Time resolution is achieved by moving the camera during a plasma discharge in a perpendicular direction through the dispersion plane of the spectrometer causing a vertical streaking across the camera face. Initial results from C-Mod as well as previous measurements from the Compact Toroid Injection Experiment (CTIX) and the Sustained Spheromak Plasma Experiment (SSPX) are presented.

Alfven continuum with toroidicity

International Nuclear Information System (INIS)

Riyopoulos, S.; Mahajan, S.M.

1985-06-01

The symmetry property of the MHD wave propagation operator is utilized to express the toroidal eigenmodes as a superposition of the mutually orthogonal cylindrical modes. Because of the degeneracy among cylindrical modes with the same frequency but resonant surfaces of different helicity the toroidal perturbation produces a zeroth order mixing of the above modes. The toroidal eigenmodes of frequency ω 0 2 have multiple resonant surfaces, with each surface shifted relative to its cylindrical position and carrying a multispectral content. Thus a single helicity toroidal antenna of frequency ω 0 couples strongly to all different helicity resonant surfaces with matching local Alfven frequency. Zeroth order coupling between modes in the continuum and global Alfven modes also results from toroidicity and degeneracy. Our perturbation technique is the MHD counterpart of the quantum mechanical methods and is applicable through the entire range of the MHD spectrum

A compact chaotic laser device with a two-dimensional external cavity structure

International Nuclear Information System (INIS)

Sunada, Satoshi; Adachi, Masaaki; Fukushima, Takehiro; Shinohara, Susumu; Arai, Kenichi; Harayama, Takahisa

2014-01-01

We propose a compact chaotic laser device, which consists of a semiconductor laser and a two-dimensional (2D) external cavity for delayed optical feedback. The overall size of the device is within 230 μm × 1 mm. A long time delay sufficient for chaos generation can be achieved with the small area by the multiple reflections at the 2D cavity boundary, and the feedback strength is controlled by the injection current to the external cavity. We experimentally demonstrate that a variety of output properties, including chaotic output, can be selectively generated by controlling the injection current to the external cavity.

Curvature-induced electrostatic drift modes in a toroidal plasma

International Nuclear Information System (INIS)

Venema, M.

1985-01-01

This thesis deals with a number of problems in the theory of linear stability of a hot, fully ionized plasma immersed in a strong magnetic field. The most widely used system to magnetically confine a plasma is the tokamak. This is a toroidal, current carrying device with a strong, externally imposed, magnetic field. The author discusses the linear theory of unstable, low-frequency waves in the gradient region, restricted to electrostatic waves. In that case the resulting radial fluxes of particles and energy are due to electric cross-field drifts. In the presence of magnetic fluctuations and small-scale reconnection phenomena, radial transport could also be predominantly along field lines. At present, it is not clear which of the two mechanisms is the dominant feature of the observed anomalous transport. First, the author introduces the theory of drift waves in toroidal geometry. Next, the electrostratic drift modes in toroidal geometry (weakly collisional regime), the equations for low-frequency waves in the strongly collisional regime and the electrostatic drift modes (strongly collisional regime) are discussed. (Auth.)

Plasma Heating and Losses in Toroidal Multipole Fields

International Nuclear Information System (INIS)

Armentrout, C. J.; Barter, J. D.; Breun, R. A.; Cavallo, A. J.; Drake, J. R.; Etzweiler,; Greenwood, J. R.

1974-01-01

The heating and loss of plasmas have been studied in three pulsed, toroidal multipole devices: a large levitated octupole, a small supported octupole and a very small supported quadrupole. Plasmas are produced by gun injection and heated by electron and ion cyclotron resonance heating and ohmic heating. Electron cyclotron heating rates have been measured over a wide range of parameters, and the results are in quantitative agreement with stochastic heating theory. Electron cyclotron resonance heating produces ions with energies larger than predicted by theory. With the addition of a toroidal field, ohmic heating gives densities as high as 10 13 cm -3 in the toroidal quadrupole and 10 12 cm -3 in the small octupole. Plasma losses for n=5 x 10 9 cm -3 plasmas are inferred from Langmuir probe and Fabry-Perot interferometer measurements, and measured with special striped collectors on the wall and rings. The loss to a levitated ring is measured using a modulated light beam telemeter. The confinement is better than Bohm but considerably worse than classical. Low frequency convective cells which are fixed in space are observed. These cells around the ring are diminished when a weak toroidal field is added, and loss collectors show a vastly reduced flux to the rings. Analysis of the spatial density profile shows features of B-independent diffusion. The confinement is sensitive to some kinds of dc field errors, but surprisingly insensitive to perturbations of the ac confining field

Looped star polymers show conformational transition from spherical to flat toroidal shapes.

Science.gov (United States)

Reiss, Pascal; Fritsche, Miriam; Heermann, Dieter W

2011-11-01

Inspired by the topological organization of the circular Escherichia coli chromosome, which is compacted by separate domains, we study a polymer architecture consisting of a central ring to which either looped or linear side chains are grafted. A shape change from a spherical to a toroidal organization takes place as soon as the inner ring becomes large enough for the attached arms to fit within its circumference. Building up a torus, the system flattens, depending on the effective bending rigidity of the chain induced by entropic repulsion of the attached loops and, to a lesser extent, linear arms. Our results suggest that the natural formation of a toroidal structure with a decreased amount of writhe induced by a specific underlying topology could be one driving force, among others, that nature exploits to ensure proper packaging of the genetic material within a rod-shaped, bacterial envelope.

Rotating shield ceiling for the compact ignition tokamak test cell

International Nuclear Information System (INIS)

Commander, J.C.

1986-01-01

For the next phase of the United States fusion program, a compact, high-field, toroidal ignition machine with liquid nitrogen cooled copper coils, designated the Compact Ignition Tokamak (CIT), is proposed. The CIT machine will be housed in a test cell with design features developed during preconceptual design. Configured as a right cylinder, the selected test cell design features: a test cell and basement with thick concrete shielding walls, and floor; leak tight tritium seals; and operational characteristics well suited to the circular CIT machine configuration and radially oriented ancillary equipment and systems

Toroidal current asymmetry in tokamak disruptions

Science.gov (United States)

Strauss, H. R.

2014-10-01

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

Creating compact and microscale features in paper-based devices by laser cutting.

Science.gov (United States)

Mahmud, Md Almostasim; Blondeel, Eric J M; Kaddoura, Moufeed; MacDonald, Brendan D

2016-11-14

In this work we describe a fabrication method to create compact and microscale features in paper-based microfluidic devices using a CO 2 laser cutting/engraving machine. Using this method we are able to produce the smallest features with the narrowest barriers yet reported for paper-based microfluidic devices. The method uses foil backed paper as the base material and yields inexpensive paper-based devices capable of using small fluid sample volumes and thus small reagent volumes, which is also suitable for mass production. The laser parameters (power and laser head speed) were adjusted to minimize the width of hydrophobic barriers and we were able to create barriers with a width of 39 ± 15 μm that were capable of preventing cross-barrier bleeding. We generated channels with a width of 128 ± 30 μm, which we found to be the physical limit for small features in the chromatography paper we used. We demonstrate how miniaturizing of paper-based microfluidic devices enables eight tests on a single bioassay device using only 2 μL of sample fluid volume.

Tokamak with liquid metal toroidal field coil

International Nuclear Information System (INIS)

Ohkawa, T.; Schaffer, M.J.

1981-01-01

Tokamak apparatus includes a pressure vessel for defining a reservoir and confining liquid therein. A toroidal liner disposed within the pressure vessel defines a toroidal space within the liner. Liquid metal fills the reservoir outside said liner. Electric current is passed through the liquid metal over a conductive path linking the toroidal space to produce a toroidal magnetic field within the toroidal space about the major axis thereof. Toroidal plasma is developed within the toroidal space about the major axis thereof

TOROID II

Science.gov (United States)

2009-01-01

three axis fluxgate magnetometer , CMOS sun and star sensors, and a Kalman filter. The work and tasks that have been accomplished on the TOROID... magnetometer . The problem was found to be a missing ferrite bead which connects the 12V power supply to the op-amps which are used to appropriately...establish an overall operational timeline for TOROID. Testing and calibration was performed on the three-axis magnetometer which is primary attitude

Equivelar toroids with few flag-orbits

OpenAIRE

Collins, José; Montero, Antonio

2018-01-01

An $(n+1)$-toroid is a quotient of a tessellation of the $n$-dimensional Euclidean space with a lattice group. Toroids are generalizations of maps in the torus on higher dimensions and also provide examples of abstract polytopes. Equivelar toroids are those that are induced by regular tessellations. In this paper we present a classification of equivelar $(n+1)$-toroids with at most $n$ flag-orbits; in particular, we discuss a classification of $2$-orbit toroids of arbitrary dimension.

Neoclassical transport in toroidal systems

International Nuclear Information System (INIS)

Wobig, H.

1992-01-01

The neoclassical theory of general toroidal equilibria is reformulated. The toroidal equilibrium of tokamaks and stellarators are described in Hamada coordinates. The relevant geometrical parameters are identified and it is shown how the reduction of Pfirsch-Schluter currents affects neoclassical transport and bootstrap effects. General flux-friction relations between thermodynamic forces and fluxes are derived. In drift-kinetic approximation the neoclassical transport coefficients are Onsager symmetric. Since a toroidal loop voltage is included, the theory is valid for all toroidal systems. (Author)

Analytic model of the radiation-dominated decay of a compact toroid

International Nuclear Information System (INIS)

Auerbach, S.P.

1981-01-01

The coaxial-gun, compact-torus experiments at LLNL and LASNL are believed to be radiation-dominated, in the sense that most or all of the input energy is lost by impurity radiation. This paper presents a simple analytic model of the radiation-dominated decay of a compact torus, and demonstrates that several striking features of the experiment (finite lifetime, linear current decay, insensitivity of the lifetime to density or stored magnetic energy) may also be explained by the hypothesis that impurity radiation dominates the energy loss. The model incorporates the essential features of the more elaborate 1 1/2-D simulations of Shumaker et al., yet is simple enough to be solved exactly. Based on the analytic results, a simple criterion is given for the maximum tolerable impurity density

Compact neutron generator

Science.gov (United States)

Leung, Ka-Ngo; Lou, Tak Pui

2005-03-22

A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

Fast Dump of the ATLAS Toroids

CERN Document Server

Dudarev, A; Volpini, Giovanni; Dudarev, Alexey; Kate, Herman Ten

2010-01-01

The toroidal magnet system of the ATLAS Detector at CERN consists of a Barrel Toroid (BT) and two End Cap Toroids (ECT-A and ECT-C). Each toroid is built up from eight racetrack coils wound with an aluminum stabilized NbTi conductor and indirectly cooled by forced flow liquid helium. The three toroids operate in series at 20.5 kA with a total stored energy of 1.5 GJ. In order to verify the reliability and effectiveness of the quench protection system, series of fast dump tests have been performed first of the single toroids and finally of the entire toroidal magnet system. In this paper a model to simulate the fast dump of the ATLAS toroids in single mode operation and in full system configuration is presented. The model is validated through comparison with measured data extracted from the ramp-and-quench runs. The calculated energy dissipation in the various coils is in very good agreement (within 1-2\\%) with the enthalpy changes estimated from the temperature measurements of the different parts of the cold ...

Compaction of spent nuclear fuel cans

International Nuclear Information System (INIS)

Sullivan, H.

1985-01-01

Hydraulic press apparatus for compacting waste material eg. spent nuclear fuel cans comprises a fixed frame, a movable cross head, a press crown and three groups of piston/cylinder devices; having their pistons connected to the cross head and their cylinders secured to the press crown. A control means connects the first group of devices to hydraulic fluid in a reservoir which is pressurised initially by gas from gas accumulators to move the cross head and a quill secured thereto towards the frame base to compact the waste at a first high rate under a first high loading. Compaction then proceeds at a lower second rate at a lower second loading as the hydraulic fluid in the reservoir is pressurised by a pump. At two subsequent stages of compaction of the waste at which resistance increases causing a pressure rise in cylinders the control means causes hydraulic fluid to be passed to the second group of devices and thence to the third group of devices, the compaction rate reducing at each stage but the compaction force increasing. (author)

A model for the neoclassical toroidal viscosity effect on Edge plasma toroidal rotation

Energy Technology Data Exchange (ETDEWEB)

Miron, I.G. [National Institute for Laser, Plasma and Radiation Physics, Euratom-MEdC Association, Bucharest (Romania)

2013-11-15

A semianalytic expression for the edge plasma angular toroidal rotation frequency that includes the neoclassical toroidal viscosity braking influence is obtained. Based on the model presented in a previous paper [I.G. Miron, Contrib. Plasma Phys. 53, 214 (2013)], the less destabilizing error field spectrum is found in order to minimize the nonlinear effect of the NTV on the toroidal rotation of the edge of the plasma. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

A comparison between linear and toroidal Extrap systems

International Nuclear Information System (INIS)

Lehnert, B.

1988-09-01

The Extrap scheme consists of a Z-pinch immersed in an octupole field generated by currents in a set of external conductors. A comparison between linear and toroidal Extrap geometry is made in this paper. As compared to toroidal systems, linear geometry has the advantages of relative simplicity and of a current drive by means of electrodes. Linear devices are convenient for basic studies of Extrap, at moderately high pinch currents and plasma temperatures. Within the parameter ranges of experiments at high pinch currents and plasma temperatures, linear systems have on the other hand some substantial disadvantages, on account of the plasma interaction with the end regions. This results in a limitation of the energy confinement time, and leads in the case of an ohmically heated plasma to excessively high plasma densities and small pinch radii which also complicate the introduction of the external conductors. (author)

Basic toroidal Effects on Alfven Wave Current in Small Aspect Ratio Tokamaks

International Nuclear Information System (INIS)

Burma, C.; Cuperman, S.; Komoshvili, K.

1998-01-01

The Alfven wave current drive (AWCD) in small aspect ratio Tokamaks is properly calculated, with consideration of the basic toroidicity effects present in (i) the dielectric tensor-operator (involving the strongly toroidal equilibrium profiles), (ii) the structure of the r.f. fields obtained as a solution of the wave equation (through Maxwell's equations' toroidal operators as well as the conversion rate and conversion layer location, depending also on the equilibrium profiles) and (iii) the formulation of the AWCD (which, besides its dependence on the r.f. fields - affected by toroidicity as mentioned at points (i) and (ii) - also requires the equilibrium-magnetic-surface averaging of non-resonant forces involved). Thus, we consider consistent equilibrium profiles with neo-classical conductivity corresponding to an ohmic START-like discharge; use a resistive (anisotropic) MHD dielectric tensor-operator Edith practically no limitations, adequate to describe the plasma response in the pre-heated stage ; solve numerically the 2(1/2)D full- wave equation by the aid of an advanced finite element code developed in; and evaluate the AWCD by the aid of the recently proposed, quite general formulation holding in the case of strongly toroidal fusion devices and including contributions due to helicity injection, momentum transfer and plasma Bow. A general discussion of the results obtained in this work is presented

Tunable plasmonic toroidal terahertz metamodulator

Science.gov (United States)

Gerislioglu, Burak; Ahmadivand, Arash; Pala, Nezih

2018-04-01

Optical modulators are essential and strategic parts of micro- and nanophotonic circuits to encode electro-optical signals in the optical domain. Here, by using arrays of multipixel toroidal plasmonic terahertz (THz) metamolecules, we developed a functional plasmonic metamodulator with high efficiency and tunability. Technically, the dynamic toroidal dipole induces nonradiating charge-current arrangements leading to have an exquisite role in defining the inherent spectral features of various materials. By categorizing in a different family of multipoles far from the traditional electromagnetic multipoles, the toroidal dipole corresponds to poloidal currents flowing on the surface of a closed-loop torus. Utilizing the sensitivity of the optically driven toroidal momentum to the incident THz beam power and by employing both numerical tools and experimental analysis, we systematically studied the spectral response of the proposed THz plasmonic metadevice. In this Rapid Communication, we uncover a correlation between the existence and the excitation of the toroidal response and the incident beam power. This mechanism is employed to develop THz toroidal metamodulators with a strong potential to be employed for practical advanced and next-generation communication, filtering, and routing applications.

Goya - an MHD equilibrium code for toroidal plasmas

International Nuclear Information System (INIS)

Scheffel, J.

1984-09-01

A description of the GOYA free-boundary equilibrium code is given. The non-linear Grad-Shafranov equation of ideal MHD is solved in a toroidal geometry for plasmas with purely poloidal magnetic fields. The code is based on a field line-tracing procedure, making storage of a large amount of information on a grid unnecessary. Usage of the code is demonstrated by computations of equi/libria for the EXTRAP-T1 device. (Author)

Ion cyclotron-resonance heating in a toroidal octupole

International Nuclear Information System (INIS)

Barter, J.D.; Sprott, J.C.

1975-01-01

rf power near the ion cyclotron-resonance frequency has been used to produce a hundredfold increase (from approximately-less-than1 to approx.100 eV) in the ion temperature in a toroidal octupole device. The heating produces no noticeable instabilities or other deleterious effects except for a high reflux of neutrals from the walls. The heating rate is consistent with theory and the limiting ion temperature is determined by charge-exchange losses

X-ray imaging with toroidal mirror

International Nuclear Information System (INIS)

Aoki, Sadao; Sakayanagi, Yoshimi

1978-01-01

X-ray imaging is made with a single toroidal mirror or two successive toroidal mirrors. Geometrical images at the Gaussian image plane are described by the ray trace. Application of a single toroidal mirror to small-angle scattering is presented. (author)

A compact electroencephalogram recording device with integrated audio stimulation system

Science.gov (United States)

Paukkunen, Antti K. O.; Kurttio, Anttu A.; Leminen, Miika M.; Sepponen, Raimo E.

2010-06-01

A compact (96×128×32 mm3, 374 g), battery-powered, eight-channel electroencephalogram recording device with an integrated audio stimulation system and a wireless interface is presented. The recording device is capable of producing high-quality data, while the operating time is also reasonable for evoked potential studies. The effective measurement resolution is about 4 nV at 200 Hz sample rate, typical noise level is below 0.7 μVrms at 0.16-70 Hz, and the estimated operating time is 1.5 h. An embedded audio decoder circuit reads and plays wave sound files stored on a memory card. The activities are controlled by an 8 bit main control unit which allows accurate timing of the stimuli. The interstimulus interval jitter measured is less than 1 ms. Wireless communication is made through bluetooth and the data recorded are transmitted to an external personal computer (PC) interface in real time. The PC interface is implemented with LABVIEW® and in addition to data acquisition it also allows online signal processing, data storage, and control of measurement activities such as contact impedance measurement, for example. The practical application of the device is demonstrated in mismatch negativity experiment with three test subjects.

Collisional boundary layer analysis for neoclassical toroidal plasma viscosity in tokamaks

Czech Academy of Sciences Publication Activity Database

Shaing, K.C.; Cahyna, Pavel; Bécoulet, M.; Park, J.-K.; Sabbagh, S.A.; Chu, M.S.

2008-01-01

Roč. 15, č. 8 (2008), 082506-1-7 ISSN 1070-664X Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma boundary layers * plasma toroidal confinement * Tokamak devices Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.427, year: 2008 http://dx.doi.org/10.1063/1.2969434

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

Science.gov (United States)

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.

Torus type thermonuclear device

International Nuclear Information System (INIS)

Imura, Yasuya.

1979-01-01

Purpose: To attain supporting effect against electromagnetic force and moderate the inner stress applied to toroidal coils due to thermal expansion by intervening a stress relaxation member between the outer circumferential side of a torus and a support device in toroidal coils. Constitution: Toroidal coils for confining a plasma within a torus vacuum container is supported on a support secured to upper and lower bases. A thermoplastic stress relaxation material of a low young's modulus is put between the outer circumferential side of the torus container and the torus outer circumferential side of the support in the toroidal coil. Thermoplastic resin is best suited to the stress relaxation substance, although tetrafluoro resin may be used as the stress relaxation substance while packing non-woven tetron fabric or non-woven glass fabric impregnated with varnish in a gap between the stress relaxation substance and the support or the toroidal coils. (Seki, T.)

Experimental studies of equilibrium in the toroidal Extrap T1 experiment

International Nuclear Information System (INIS)

Drake, J.R.; Hedin, E.R.; Karlsson, P.; Jin Li; Saetherblom, H.E.

1989-03-01

Experimental studies of a toroidal, high-beta plasma discharge with a non-circular cross-section are described. In Extrap T1, four toroidal, current-carrying rings outside the plasma discharge current channel produce a separatrix which bounds the plasma. Plasma currents of up to 40 kA are induced, operating with a toroidal field of up to 0.2 T. The major radius of the device is 0.45 m and the average minor radius of the current channel is about 40 mm. The discharge pulse is approximately 100 μsec long. For the discharges reported here, the peak current density on the discharge axis is about 9 MA/m 2 , which corresponds to an on-axis safety factor q o of about 0.1. The plasma density is in the range n ≅ 0.2 to 1 x 10 21 m -3 , and the electron temperature is in the range T e ≅ 10 to 30 eV. Magnetic flux plots of the experiment have been studied using magnetic probes and current and pressure profiles have been derived from the magnetic data

Ventricular assist device implantation in a young patient with non-compaction cardiomyopathy and hereditary spherocytosis.

Science.gov (United States)

Huenges, Katharina; Panholzer, Bernd; Cremer, Jochen; Haneya, Assad

2018-04-01

A case of a 15-year-old female patient with acute heart failure due to non-compaction cardiomyopathy and hereditary anaemia (hereditary spherocytic elliptocytosis) requiring ventricular assist device implantation as a bridge to transplantation is presented. The possible effects of mechanical stress on erythrocytes potentially induced by mechanical circulatory support remains unclear, but it may lead to haemolytic crisis in patients suffering from hereditary anaemia. In our case, ventricular assist device therapy was feasible, and haematological complications did not occur within 6 weeks of bridging our patient to heart transplantation.

Observations of toroidal and poloidal rotation in the high beta tokamak Torus II

International Nuclear Information System (INIS)

Kostek, C.A.

1983-01-01

The macroscopic rotation of plasma in a toroidal containment device is an important feature of the equilibrium. Toroidal and poloidal rotation in the high beta tokamak Torus II is measured experimentally by examining the Doppler shift of the 4685.75 A He II line emitted from the plasma. The toroidal flow at an average velocity of 1.6 x 10 6 cm/sec, a small fraction of the ion thermal speed, moves in the same direction as the toroidal plasma current. The poloidal flow follows the ion diamagnetic current direction, also at an average speed of 1.6 x 10 6 cm/sec. In view of certain ordering parameters, the toroidal flow is compared with predictions from neoclassical theory in the collosional, Pfirsch-Schluter regime. The poloidal motion, however results from an E x B drift in a positive radial electric field, approaching a stable ambipolar state. This radial electric field is determined from theory by using the measured poloidal velocity. Mechanisms for the time evolution of rotation are also examined. It appears that the circulation damping is governed by a global decay of the temperature and density gradients which, in turn, may be functions of radiative cooling, loss of equilibrium due to external field decay, or the emergence of a growing instability, occasionally observed in CO 2 interferometry measurements

Ultra-Compact 100 × 100 μm2 Footprint Hybrid Device with Spin-Valve Nanosensors

Directory of Open Access Journals (Sweden)

Diana C. Leitao

2015-12-01

Full Text Available Magnetic field mapping with micrometric spatial resolution and high sensitivity is a challenging application, and the technological solutions are usually based on large area devices integrating discrete magnetic flux guide elements. In this work we demonstrate a high performance hybrid device with improved field sensitivity levels and small footprint, consisting of a ultra-compact 2D design where nanometric spin valve sensors are inserted within the gap of thin-film magnetic flux concentrators. Pole-sensor distances down to 400 nm are demonstrated using nanofabrication techniques combined with an optimized liftoff process. These 100 × 100 μm 2 pixel sensors can be integrated in modular devices for surface mapping without moving parts.

Tearing modes in toroidal geometry

International Nuclear Information System (INIS)

Connor, J.W.; Cowley, S.C.; Hastie, R.J.; Hender, T.C.; Hood, A.; Martin, T.J.

1988-01-01

The separation of the cylindrical tearing mode stability problem into a resistive resonant layer calculation and an external marginal ideal magnetohydrodynamic (MHD) calculation (Δ' calculation) is generalized to axisymmetric toroidal geometry. The general structure of this separation is analyzed and the marginal ideal MHD information (the toroidal generalization of Δ') required to discuss stability is isolated. This can then, in principle, be combined with relevant resonant layer calculations to determine tearing mode growth rates in realistic situations. Two examples are given: the first is an analytic treatment of toroidally coupled (m = 1, n = 1) and (m = 2, n = 1) tearing modes in a large aspect ratio torus; the second, a numerical treatment of the toroidal coupling of three tearing modes through finite pressure effects in a large aspect ratio torus. In addition, the use of a coupling integral approach for determining the stability of coupled tearing modes is discussed. Finally, the possibility of using initial value resistive MHD codes in realistic toroidal geometry to determine the necessary information from the ideal MHD marginal solution is discussed

Comparative investigation of ELM control based on toroidal modelling of plasma response to RMP fields

Science.gov (United States)

Liu, Yueqiang

2016-10-01

The type-I edge localized mode (ELM), bursting at low frequency and with large amplitude, can channel a substantial amount of the plasma thermal energy into the surrounding plasma-facing components in tokamak devices operating at the high-confinement mode, potentially causing severe material damages. Learning effective ways of controlling this instability is thus an urgent issue in fusion research, in particular in view of the next generation large devices such as ITER and DEMO. Among other means, externally applied, three-dimensional resonant magnetic perturbation (RMP) fields have been experimentally demonstrated to be successful in mitigating or suppressing the type-I ELM, in multiple existing devices. In this work, we shall report results of a comparative study of ELM control using RMPs. Comparison is made between the modelled plasma response to the 3D external fields and the observed change of the ELM behaviour on multiple devices, including MAST, ASDEX Upgrade, EAST, DIII-D, JET, and KSTAR. We show that toroidal modelling of the plasma response, based on linear and quasi-linear magnetohydrodynamic (MHD) models, provides essential insights that are useful in interpreting and guiding the ELM control experiments. In particular, linear toroidal modelling results, using the MARS-F code, reveal the crucial role of the edge localized peeling-tearing mode response during ELM mitigation/suppression on all these devices. Such response often leads to strong peaking of the plasma surface displacement near the region of weak equilibrium poloidal field (e.g. the X-point), and this provides an alternative practical criterion for ELM control, as opposed to the vacuum field based Chirikov criteria. Quasi-linear modelling using MARS-Q provides quantitative interpretation of the side effects due to the ELM control coils, on the plasma toroidal momentum and particle confinements. The particular role of the momentum and particle fluxes, associated with the neoclassical toroidal

A novel technique for impaction bone grafting in acetabular reconstruction of revision total hip arthroplasty using an ex vivo compaction device

International Nuclear Information System (INIS)

Akiyama, Haruhiko; Takemoto, Mitsuru; Morishima, Takkan

2011-01-01

Impaction bone grafting allows restoration of the acetabular bone stock in revision hip arthroplasty. The success of this technique depends largely on achieving adequate initial stability of the component. To obtain well-compacted, well-graded allograft aggregates, we developed an ex vivo compaction device to apply it in revision total hip arthroplasty on the acetabular side, and characterized mechanical properties and putative osteoconductivity of allograft aggregates. Morselized allograft bone chips were compacted ex vivo using the creep technique and subsequent impaction technique to form the bone aggregates. Impaction allograft reconstruction of the acetabulum using an ex vivo compaction device was performed on eight hips. The mechanical properties and three-dimensional micro-CT-based structural characteristics of the bone aggregates were investigated. In clinical practice, this technique offered good reproducibility in reconstructing the cavity and the segmental defects of the acetabulum, with no migration and no loosening of the component. In vitro analysis showed that the aggregates generated from 25 g fresh-frozen bone chips gained compression stiffness of 13.5-15.4 MPa under uniaxial consolidation strain. The recoil of the aggregates after compaction was 2.6-3.9%. The compression stiffness and the recoil did not differ significantly from those measured using a variety of proportions of large- and small-sized bone chips. Micro-CT-based structural analysis revealed average pore sizes of 268-299 μm and average throat diameter of pores in the bone aggregates of more than 100 μm. These sizes are desirable for osteoconduction, although large interconnected pores of more than 500 μm were detectable in association with the proportion of large-sized bone chips. Cement penetration into the aggregates was related to the proportion of large-sized bone chips. This study introduces the value of an ex vivo compaction device in bone graft compaction in clinical

Toroid magnet test facility

CERN Multimedia

2002-01-01

Because of its exceptional size, it was not feasible to assemble and test the Barrel Toroid - made of eight coils - as an integrated toroid on the surface, prior to its final installation underground in LHC interaction point 1. It was therefore decided to test these eight coils individually in a dedicated test facility.

Encoding technique for high data compaction in data bases of fusion devices

International Nuclear Information System (INIS)

Vega, J.; Cremy, C.; Sanchez, E.; Portas, A.; Dormido, S.

1996-01-01

At present, data requirements of hundreds of Mbytes/discharge are typical in devices such as JET, TFTR, DIII-D, etc., and these requirements continue to increase. With these rates, the amount of storage required to maintain discharge information is enormous. Compaction techniques are now essential to reduce storage. However, general compression techniques may distort signals, but this is undesirable for fusion diagnostics. We have developed a general technique for data compression which is described here. The technique, which is based on delta compression, does not require an examination of the data as in delayed methods. Delta values are compacted according to general encoding forms which satisfy a prefix code property and which are defined prior to data capture. Several prefix codes, which are bit oriented and which have variable code lengths, have been developed. These encoding methods are independent of the signal analog characteristics and enable one to store undistorted signals. The technique has been applied to databases of the TJ-I tokamak and the TJ-IU torsatron. Compaction rates of over 80% with negligible computational effort were achieved. Computer programs were written in ANSI C, thus ensuring portability and easy maintenance. We also present an interpretation, based on information theory, of the high compression rates achieved without signal distortion. copyright 1996 American Institute of Physics

Thermonuclear device

International Nuclear Information System (INIS)

Yagi, Yasuomi; Takahashi, Ken; Hashimoto, Hiroshi.

1984-01-01

Purpose: To improve the plasma confining performances by bringing the irregular magnetic fields nearly to zero and decreasing the absolute value of the irregular magnetic fields at every positions. Constitution: The winding direction of a plurality of coil elements, for instance, double pan cake coils of toroidal coils in a torus type or mirror type thermonuclear device are reversed to each other in their laminating direction, whereby the irregular magnetic fields due to the coil-stepped portions in each toroidal coils are brought nearly to zero. This enables to bring the average irregular magnetic fields as a whole in the thermonuclear device nearly to zero, as well as, decrease the absolute value of the irregular magnetic fields in each positions. Thus, the plasma confining performances can be improved. (Moriyama, K.)

Toroidal electron beam energy storage for controlled fusion

International Nuclear Information System (INIS)

Clark, W.; Korn, P.; Mondelli, A.; Rostoker, N.

1976-01-01

In the presence of an external magnetic field stable equilibria exist for an unneutralized electron beam with ν/γ >1. As a result, it is in principle, possible to store very large quantities of energy in relatively small volumes by confining an unneutralized electron beam in a Tokamak-like device. The energy is stored principally in the electrostatic and self-magnetic fields associated with the beam and is available for rapid heating of pellets for controlled fusion. The large electrostatic potential well in such a device would be sufficient to contain energetic alpha particles, thereby reducing reactor wall bombardment. This approach also avoids plasma loss and wall bombardment by charge exchange neutrals. The conceptual design of an electrostatic Tokamak fusion reactor (ETFR) is discussed. A small toroidal device (the STP machine) has been constructed to test the principles involved. Preliminary experiments on this device have produced electron densities approximately 10% of those required in a reactor

Considerations of coil protection and electrical connection schemes in large superconducting toroidal magnet system

International Nuclear Information System (INIS)

Yeh, H.T.

1976-03-01

A preliminary comparison of several different coil protection and electrical connection schemes for large superconducting toroidal magnet systems (STMS) is carried out. The tentative recommendation is to rely on external dump resistors for coil protection and to connect the coils in the toroidal magnet in several parallel loops (e.g., every fourth coil is connected into a single series loop). For the fault condition when a single coil quenches, the quenched coil should be isolated from its loop by switching devices. The magnet, as a whole, should probably be discharged if more than a few coils have quenched

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

Energy Technology Data Exchange (ETDEWEB)

Hegna, C. C. [Departments of Engineering Physics and Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2016-05-15

The impact of sheared toroidal rotation on the evolution of pressure driven magnetic islands in tokamak plasmas is investigated using a resistive magnetohydrodynamics model augmented by a neoclassical Ohm's law. Particular attention is paid to the asymptotic matching data as the Mercier indices are altered in the presence of sheared flow. Analysis of the nonlinear island Grad-Shafranov equation shows that sheared flows tend to amplify the stabilizing pressure/curvature contribution to pressure driven islands in toroidal tokamaks relative to the island bootstrap current contribution. As such, sheared toroidal rotation tends to reduce saturated magnetic island widths.

Toroidal equilibrium of a non-neutral plasma with toroidal current, inertia and pressure

International Nuclear Information System (INIS)

Bhattacharyya, S.N.; Avinash, K.

1992-01-01

Equilibrium of non-neutral clouds in a toroidal vessel with toroidal magnetic field is demonstrated in the presence of a toroidal current, finite mass and finite pressure. With a toroidal current, it is shown that in a large-aspect-ratio conducting torus the equilibrium is governed by competition between forces produced by image charges and image currents. When μ 0 ε 0 E r 2 >B θ 2 (whe re E r and B θ are the self electrostatic and self magnetic fields of the cloud), the confinement is electrostatic and plasma shifts inwards; when μ 0 ε 0 E r 2 θ 2 , the confinement is magnetic and plasma shifts outwards. For μ 0 ε 0 E r 2 = B θ 2 there is no equilibrium. With finite mass or finite pressure, it is shown, in a large-aspect-ratio approximation, that the fluid drift surfaces and equipotential surfaces are displaced with respect to each other. In both cases the fluid drift surfaces are shifted inwards from the equipotential surfaces. (author)

Advances in Compact Torus research. Report on the IAEA technical committee meeting, held in Sydney, Australia, 4-7 March 1985

Energy Technology Data Exchange (ETDEWEB)

Durance, G

1985-08-01

A Compact Torus (CT) is a low-aspect-ratio, axisymmetric, closed-magnetic-field-line configuration with no vessel wall or magnetic field coils linking the hole in the plasma toroid. The potential reactor advantages include high beta, simple geometry, high power density, and translation of the toroid. FRC (Field Reversed Configuration) have negligible toroidal magnetic fields; equilibria tend to be elongated. Gross stability is observed for several Alfven times, but transport mechanisms and confinement time scaling are poorly understood. Translation experiments are expanding the accessable parameter space. Spheromaks have comparable toroidal and poloidal fields. The configuration is related to the RFP although the toroidal field is generated by internal plasma currents. Detached mode (plasma and gun or flux core not connected) and linked mode have been studied. Rotamaks use a rotating magnetic field to maintain the plasma toroidal current; the drive mechanism is analagous to an induction motor. There has been no evidence for gross instabilities although temperatures are low. Particle rings generate CT with particle gyroradii comparable to plasma dimensions. The large orbits may aid in gross MHD stability.

Viscous damping of toroidal angular momentum in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Stacey, W. M. [Georgia Tech Fusion Research Center, Atlanta, Georgia 30332 (United States)

2014-09-15

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

Effects of orbit squeezing on neoclassical toroidal plasma viscosity in tokamaks

Czech Academy of Sciences Publication Activity Database

Shaing, K.C.; Sabbagh, S.A.; Chu, M.S.; Bécoulet, M.; Cahyna, Pavel

2008-01-01

Roč. 15, č. 8 (2008), 082505-1-082505-8 ISSN 1070-664X Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma boundary layers * plasma instability * plasma magnetohydrodynamics * plasma toroidal confinement * plasma transport processes * Tokamak devices Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.427, year: 2008 http://dx.doi.org/10.1063/1.2965146

Toroidal Trivelpiece-Gould modes

International Nuclear Information System (INIS)

Stoessel, F.P.

1979-01-01

Electron plasma waves are treated in quasi-electrostatic approximation in a toroidal cavity of rectangular cross-section in an infinitely strong azimuthal magnetic field. The differential equation for the electrostatic potential, derived from fluid equations, can be separated using cylindrical coordinates. The eigenvalue problem for the radial dependence is solved numerically by a shooting method. Eigenvalues are given for different aspect ratios. Comparison with appropriate modes of the straight geometry shows that the toroidal frequencies generally lie some percent above those for the straight case. Plots of the eigenfunctions demonstrate clearly the influence of toroidicity. The deviation from symmetry (which should appear for straight geometry) depends not only on the aspect ratio but also strongly on the mode numbers. (author)

Physical mechanism determining the radial electric field and its radial structure in a toroidal plasma

International Nuclear Information System (INIS)

Ida, Katsumi; Miura, Yukitoshi; Itoh, Sanae

1994-10-01

Radial structures of plasma rotation and radial electric field are experimentally studied in tokamak, heliotron/torsatron and stellarator devices. The perpendicular and parallel viscosities are measured. The parallel viscosity, which is dominant in determining the toroidal velocity in heliotron/torsatron and stellarator devices, is found to be neoclassical. On the other hand, the perpendicular viscosity, which is dominant in dictating the toroidal rotation in tokamaks, is anomalous. Even without external momentum input, both a plasma rotation and a radial electric field exist in tokamaks and heliotrons/torsatrons. The observed profiles of the radial electric field do not agree with the theoretical prediction based on neoclassical transport. This is mainly due to the existence of anomalous perpendicular viscosity. The shear of the radial electric field improves particle and heat transport both in bulk and edge plasma regimes of tokamaks. (author) 95 refs

Toroidal effects on drift wave turbulence

Energy Technology Data Exchange (ETDEWEB)

LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.

1992-09-23

The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling.

Toroidal effects on drift wave turbulence

International Nuclear Information System (INIS)

LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.

1992-01-01

The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling

Toroidal asymmetries in divertor impurity influxes in NSTX

Directory of Open Access Journals (Sweden)

F. Scotti

2017-08-01

Full Text Available Toroidal asymmetries in divertor carbon and lithium influxes were observed in NSTX, due to toroidal differences in surface composition, tile leading edges, externally-applied three-dimensional (3D fields and toroidally-localized edge plasma modifications due to radio frequency heating. Understanding toroidal asymmetries in impurity influxes is critical for the evaluation of total impurity sources, often inferred from measurements with a limited toroidal coverage. The toroidally-asymmetric lithium deposition induced asymmetries in divertor lithium influxes. Enhanced impurity influxes at the leading edge of divertor tiles were the main cause of carbon toroidal asymmetries and were enhanced during edge localized modes. Externally-applied 3D fields led to strike point splitting and helical lobes observed in divertor impurity emission, but marginal changes to the toroidally-averaged impurity influxes. Power coupled to the scrape-off layer SOL plasma during radio frequency (RF heating of H-mode discharges enhanced impurity influxes along the non-axisymmetric divertor footprint of flux tubes connecting to plasma in front of the RF antenna.

General Atomic's superconducting toroidal field coil concept

International Nuclear Information System (INIS)

Alcorn, J.; Purcell, J.

1978-01-01

General Atomic's concept for a superconducting toroidal field coil is presented. The concept is generic for large tokamak devices, while a specific design is indicated for a 3.8 meter (major radius) ignition/burn machine. The concept utilizes bath cooled NbTi conductor to generate a peak field of 10 tesla at 4.2 K. The design is simple and straightforward, requires a minimum of developmental effort, and draws extensively upon the perspective of past experience in the design and construction of large superconducting magnets for high energy physics. Thus, the primary emphasis is upon economy, reliability, and expeditious construction scheduling. (author)

In-vessel remote maintenance of the Compact Ignition Tokamak

International Nuclear Information System (INIS)

Tabor, M.A.; Hager, E.R.; Creedon, R.L.; Fisher, M.V.; Atkin, S.D.

1987-01-01

The Compact Ignition Tokamak (CIT) is the first deuterium-tritium (D-T) fusion device that will study the physics of an ignited plasma. The ability of the tokamak vacuum vessel to be maintained remotely while under vacuum has not been fully demonstrated on previous machines, and this ability will be critical to the efficient and safe operation of ignition devices. Although manned entry into the CIT vacuum vessel will be possible during the nonactivated stages of operation, remotely automated equipment will be used to assist in initial assembly of the vessel as well as to maintain all in-vessel components once the D-T burn is achieved. Remote maintenance and operation will be routinely required for replacement of thermal protection tiles, inspection of components, leak detection, and repair welding activities. Conceptual design to support these remote maintenance activities has been integrated with the conceptual design of the in-vessel components to provide a complete and practical remote maintenance system for CIT. The primary remote assembly and maintenance operations on CIT will be accomplished through two dedicated 37- x 100-cm ports on the main toroidal vessel. Each port contains a single articulated boom manipulator (ABM), which is capable of accessing half of the torus. The proposed ABM consists of a movable carriage assembly, telescoping two-part mast, and articulated link sections. 1 ref

Review of the Advanced Toroidal Facility program

International Nuclear Information System (INIS)

Lyon, J.F.; Murakami, M.

1987-01-01

This report summarizes the history and design goals of the Advanced Toroidal Facility (ATF). The ATF is nearing completion at ORNL with device completion expected in May 1987 and first useful plasma operation in June/July 1987. ATF is a moderate-aspect-ratio torsatron, the world's largest stellarator facility with R = 2.1 m, α bar = 0.3 m and B = 2 T (5-s pulse) or 1 T (steady-state capability). It has been specifically designed to support the US tokamak program by studying important toroidal confinement issues in a similar magnetic geometry that allows external control of the magnetic configuration properties and their radial profiles: transform, shear, well depth, shaping, axis topology, etc. ATF will operate in a current-free model which allows separation of current-driven and pressure-driven plasma behavior. It also complements the world stellarator program in its magnetic configuration (between Heliotron-E and W VII-AS) and its capabilities (large size, good access, steady state capability, second stability access, etc.). For both roles ATF will require high-power long-pulse heating to carry out its physics goals since the high power NBI pulse is limited to 0.3 s. The ATF program focuses on demonstrating the principles of high-beta, steady-state operation in toroidal geometry through its study of: (1) scaling of beta limits with magnetic configuration properties and the plasma behavior in the second stability regime; (2) transport scaling at low collisionality and the role/control of electric field; (3) control of plasma density and impurities using divertors; (4) plasma heating with NBI, ECH, ICH, and plasma fueling with gas puffing and pellet injection; and (5) optimization of the magnetic configuration

Systems Analysis of a Compact Next Step Burning Plasma Experiment

International Nuclear Information System (INIS)

Jardin, S.C.; Kessel, C.E.; Meade, D.; Neumeyer, C.

2002-01-01

A new burning plasma systems code (BPSC) has been developed for analysis of a next step compact burning plasma experiment with copper-alloy magnet technology. We consider two classes of configurations: Type A, with the toroidal field (TF) coils and ohmic heating (OH) coils unlinked, and Type B, with the TF and OH coils linked. We obtain curves of the minimizing major radius as a function of aspect ratio R(A) for each configuration type for typical parameters. These curves represent, to first order, cost minimizing curves, assuming that device cost is a function of major radius. The Type B curves always lie below the Type A curves for the same physics parameters, indicating that they lead to a more compact design. This follows from that fact that a high fraction of the inner region, r < R-a, contains electrical conductor material. However, the fact that the Type A OH and TF magnets are not linked presents fewer engineering challenges and should lead to a more reliable design. Both the Type A and Type B curves have a minimum in major radius R at a minimizing aspect ratio A typically above 2.8 and at high values of magnetic field B above 10 T. The minimizing A occurs at larger values for longer pulse and higher performance devices. The larger A and higher B design points also have the feature that the ratio of the discharge time to the current redistribution time is largest so that steady-state operation can be more realistically prototyped. A sensitivity study is presented for the baseline Type A configuration showing the dependence of the results on the parameters held fixed for the minimization study

Effects of Non-Maxwellian Plasma Species on ICRF Propagation and Absorption in Toroidal Magnetic Confinement Devices

International Nuclear Information System (INIS)

Dumont, R.J.; Phillips, C.K.; Smithe, D.N.

2003-01-01

Auxiliary heating supplied by externally launched electromagnetic waves is commonly used in toroidal magnetically confined fusion experiments for profile control via localized heating, current drive and perhaps flow shear. In these experiments, the confined plasma is often characterized by the presence of a significant population of non-thermal species arising from neutral beam injection, from acceleration of the particles by the applied waves, or from copious fusion reactions in future devices. Such non-thermal species may alter the wave propagation as well as the wave absorption dynamics in the plasma. Previous studies have treated the corresponding velocity distributions as either equivalent Maxwellians, or else have included realistic distributions only in the finite Larmor radius limit. In this work, the hot plasma dielectric response of the plasma has been generalized to treat arbitrary distribution functions in the non-relativistic limit. The generalized dielectric tensor has been incorporated into a one-dimensional full wave all-orders kinetic field code. Initial comparative studies of ion cyclotron range of frequency wave propagation and heating in plasmas with nonthermal species, represented by realistic distribution functions or by appropriately defined equivalent Maxwellians, have been completed for some specific experiments and are presented

Toroidal Extrap Equilibria

International Nuclear Information System (INIS)

Scheffel, J.

1982-04-01

Ideal MHD-equilibria for the toroidal EXTRAP configuration have been computed with an equilibrium code. The free-boundary prob- lem is solved by using the condition that the current density is proportional to r on a flux surface. It is found that the toroidal Z-pinch, initially induced in the central zero-field region of a transverse octupole field, drifts radially outwards producing an inverse -D shaped cross-section. The plasma current of this high- beta equilibrium may be increased if the plasma is pushed back by altering the external confining magnetic field as demonstrated. (Author)

Demountable toroidal fusion core facility for physics optimization and fusion engineering

International Nuclear Information System (INIS)

Bogart, S.L.; Wagner, C.E.; Krall, N.A.; Dalessandro, J.A.; Weggel, C.F.; Lund, K.O.; Sedehi, S.

1986-01-01

Following a successful compact ignition tokamak (CIT) experiment, a fusion facility will be required for physics optimization (POF) and fusion engineering research (FERF). The POF will address issues such as high-beta operation, current drive, impurity control, and will test geometric and configurational variations such as the spherical torus or the reversed-field pinch (RFP). The FERF will be designed to accumulate rapidly a large neutron dose in prototypical fusion subsystems exposed to radiation. Both facilities will require low-cost replacement cores and rapid replacement times. The Demountable Toroidal Fusion Core (DTFC) facility is designed to fulfill these requirements. It would be a cost-effective stepping stone between the CIT and a demonstration fusion reactor

New material equations for electromagnetism with toroid polarizations

International Nuclear Information System (INIS)

Dubovik, V.M.; Martsenyuk, M.A.; Saha, B.

1999-09-01

With regard to the toroid contributions, a modified system of equations of electrodynamics moving continuous media has been obtained. Alternative formalisms to introduce the toroid moment contributions in the equations of electromagnetism has been worked out. The two four-potential formalism has been developed. Lorentz transformation laws for the toroid polarizations has been given. Covariant form of equations of electrodynamics of continuous media with toroid polarizations has been written. (author)

Commissioning Test of ATLAS End-Cap Toroidal Magnets

CERN Document Server

Dudarev, A; Foussat, A; Benoit, P; Jeckel, M; Olyunin, A; Kopeykin, N; Stepanov, V; Deront, L; Olesen, G; Ponts, X; Ravat, S; Sbrissa, K; Barth, J; Bremer, J; Delruelle, J; Metselaar, J; Pengo, R; Pirotte, O; Buskop, J; Baynham, D E; Carr, F S; Holtom, E

2009-01-01

The system of superconducting toroids in the ATLAS experiment at CERN consists of three magnets. The Barrel Toroid was assembled and successfully tested in 2006. Next, two End-Cap Toroids have been tested on surface at 77 K and installed in the cavern, 100-m underground. The End Cap Toroids are based on Al stabilized Nb-Ti/Cu Rutherford cables, arranged in double pancake coils and conduction cooled at 4.6 K. The nominal current is 20.5 kA at 4.1 T peak field in the windings and the stored energy is 250 MJ per toroid. Prior to final testing of the entire ATLAS Toroidal system, each End Cap Toroid passed a commissioning test up to 21 kA to guarantee a reliable performance in the final assembly. In this paper the test results are described. It includes the stages of test preparation, isolation vacuum pumping and leak testing, cooling down, step-by-step charging to full current, training quenches and quench recovery. By fast discharges the quench detection and protection system was checked to demonstrate a safe e...

Quantum mechanics of toroidal anions

International Nuclear Information System (INIS)

Afanas'ev, G.N.

1990-01-01

We consider a toroidal solenoid with an electric charge attached to it. It turns out that statistical properties of the wave function describing interacting toroidal anions depend on both their relative position and orientation. The influence of the particular gauge choice on the exchange properties of the wave function is studied. 30 refs.; 6 figs

Unified kinetic theory in toroidal systems

International Nuclear Information System (INIS)

Hitchcock, D.A.; Hazeltine, R.D.

1980-12-01

The kinetic theory of toroidal systems has been characterized by two approaches: neoclassical theory which ignores instabilities and quasilinear theory which ignores collisions. In this paper we construct a kinetic theory for toroidal systems which includes both effects. This yields a pair of evolution equations; one for the spectrum and one for the distribution function. In addition, this theory yields a toroidal generalization of the usual collision operator which is shown to have many similar properties - conservation laws, H theorem - to the usual collision operator

HIDRA: A new device for PFC and PMI development

Science.gov (United States)

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).

Low-n shear Alfven spectra in axisymmetric toroidal plasmas

International Nuclear Information System (INIS)

Cheng, C.Z.; Chance, M.S.

1985-11-01

In toroidal plasmas, the toroidal magnetic field is nonuniform over a magnetic surface and causes coupling of different poloidal harmonics. It is shown both analytically and numerically that the toroidicity not only breaks up the shear Alfven continuous spectrum, but also creates new, discrete, toroidicity-induced shear Alfven eigenmodes with frequencies inside the continuum gaps. Potential applications of the low-n toroidicity-induced shear Alfven eigenmodes on plasma heating and instabilities are addressed. 17 refs., 4 figs

Wave propagation near the lower hybrid resonance in toroidal plasmas

International Nuclear Information System (INIS)

Ohkubo, K.; Ohasa, K.; Matsuura, K.

1975-10-01

Dielectric tensor and equipotential curves (ray trajectories) of an electrostatic wave near the lower hybrid resonance are investigated for the toroidal plasma with a shear magnetic field. The ray trajectories start from the vicinity of the plasma surface, and rotate in a spiral form around the magnetic axis, and then reach the lower or upper parts of lower hybrid resonance layer. The numerical computations are performed on the parameters of JIPP T-II device with two dimensional inhomogeneity. (auth.)

Tokapole II device

International Nuclear Information System (INIS)

Sprott, J.G.

1978-05-01

A discussion is given of the design and operation of the Tokapole II device. The following topics are considered: physics considerations, vacuum vessel, poloidal field, ring and support design, toroidal field, vacuum system, initial results, and future plans

Heating of toroidal plasmas by neutral injection

International Nuclear Information System (INIS)

Stix, T.H.

1971-08-01

This paper presents a brief review of the physics of ion acceleration, charge exchange and ionization, trajectories for fast ions in toroidal magnetic fields, and fast-ion thermalization. The injection of fast atoms is found to be a highly competitive method both for heating present-day experimental toroidal plasmas and for bringing full-scale toroidal CTR plasmas to low-density ignition. 13 refs., 9 figs

Core localized toroidal Alfven eigenmodes destabilized by energetic ions in the CHS heliotron/torsatron

International Nuclear Information System (INIS)

Takechi, M.; Matsunaga, G.; Takagi, S.

1999-09-01

Toroidal Alfven eigenmodes (TAE) destabilized by the pressure gradient of energetic alpha particles may expel the alpha particles before thermalization. TAE is important for tokamaks, and for helical systems (stellarators) as well. In CHS (compact helical system) TAE localized in the plasma core are destabilized when the plasma current is induced by co-injection of neutral beams. The observed TAE exhibits a ballooning nature. The internal structure of TAE was measured with a soft X-ray detector. The soft X-ray fluctuations level for TAE is too low to obtain the radial profiles of fluctuation intensities. (Tanaka, M.)

Pareto optimal design of sectored toroidal superconducting magnet for SMES

Energy Technology Data Exchange (ETDEWEB)

Bhunia, Uttam, E-mail: ubhunia@vecc.gov.in; Saha, Subimal; Chakrabarti, Alok

2014-10-15

Highlights: • The optimization approach minimizes both the magnet size and necessary cable length of a sectored toroidal SMES unit. • Design approach is suitable for low temperature superconducting cable suitable for medium size SMES unit. • It investigates coil parameters with respect to practical engineering aspects. - Abstract: A novel multi-objective optimization design approach for sectored toroidal superconducting magnetic energy storage coil has been developed considering the practical engineering constraints. The objectives include the minimization of necessary superconductor length and torus overall size or volume, which determines a significant part of cost towards realization of SMES. The best trade-off between the necessary conductor length for winding and magnet overall size is achieved in the Pareto-optimal solutions, the compact magnet size leads to increase in required superconducting cable length or vice versa The final choice among Pareto optimal configurations can be done in relation to other issues such as AC loss during transient operation, stray magnetic field at outside the coil assembly, and available discharge period, which is not considered in the optimization process. The proposed design approach is adapted for a 4.5 MJ/1 MW SMES system using low temperature niobium–titanium based Rutherford type cable. Furthermore, the validity of the representative Pareto solutions is confirmed by finite-element analysis (FEA) with a reasonably acceptable accuracy.

Pareto optimal design of sectored toroidal superconducting magnet for SMES

International Nuclear Information System (INIS)

Bhunia, Uttam; Saha, Subimal; Chakrabarti, Alok

2014-01-01

Highlights: • The optimization approach minimizes both the magnet size and necessary cable length of a sectored toroidal SMES unit. • Design approach is suitable for low temperature superconducting cable suitable for medium size SMES unit. • It investigates coil parameters with respect to practical engineering aspects. - Abstract: A novel multi-objective optimization design approach for sectored toroidal superconducting magnetic energy storage coil has been developed considering the practical engineering constraints. The objectives include the minimization of necessary superconductor length and torus overall size or volume, which determines a significant part of cost towards realization of SMES. The best trade-off between the necessary conductor length for winding and magnet overall size is achieved in the Pareto-optimal solutions, the compact magnet size leads to increase in required superconducting cable length or vice versa The final choice among Pareto optimal configurations can be done in relation to other issues such as AC loss during transient operation, stray magnetic field at outside the coil assembly, and available discharge period, which is not considered in the optimization process. The proposed design approach is adapted for a 4.5 MJ/1 MW SMES system using low temperature niobium–titanium based Rutherford type cable. Furthermore, the validity of the representative Pareto solutions is confirmed by finite-element analysis (FEA) with a reasonably acceptable accuracy

Protection of toroidal field coils using multiple circuits

International Nuclear Information System (INIS)

Thome, R.J.; Langton, W.G.; Mann, W.R.; Pillsbury, R.D.; Tarrh, J.M.

1983-01-01

The protection of toroidal field (TF) coils using multiple circuits is described. The discharge of a single-circuit TF system is given for purposes of definition. Two-circuit TF systems are analyzed and the results presented analytically and graphically. Induced currents, maximum discharge voltages, and discharge time constants are compared to the single-circuit system. Three-circuit TF systems are analyzed. In addition to induced currents, maximum discharge voltages, and time constants, several different discharge scenarios are included. The impacts of having discharge rates versus final maximum coil temperatures as requirements are examined. The out-of-plane forces which occur in the three-circuit system are analyzed using an approximate model. The analysis of multiplecircuit TF systems is briefly described and results for a Toroidal Fusion Core Experiment (TFCX) scale device are given based on computer analysis. The advantages and disadvantages of using multiple-circuit systems are summarized and discussed. The primary disadvantages of multiple circuits are the increased circuit complexity and potential for out-of-plane forces. These are offset by the substantial reduction in maximum discharge voltages, as well as other design options which become available when using multiple circuits

System for calibration of SPEAR transport line toroids

International Nuclear Information System (INIS)

Huang, T.V.; Smith, H.; Crook, K.

1977-01-01

A one nanosecond pulse generator was developed for calibration of the intensity monitors (toroids) in the SPEAR transport lines. The generator, located at the toroid, is simple, low cost and resistant to radiation. The generator and its connection to the standard SLAC toroid calibration system are described

Toroidal deuteron accelerator for Mo-98 neutron activation

Energy Technology Data Exchange (ETDEWEB)

Araujo, Wagner L., E-mail: wagner.leite@ifnmg.edu.br, E-mail: tprcampos@pq.cnpq.br [Instituto Federal do Norte de Minas Gerais (IFN-MG), Montes Claros, MG (Brazil); Campos, Tarcisio P.R. Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

2017-07-01

The radionuclide Tc-{sup 99m} is the most useful radioisotope in nuclear medicine. It can be produced by the Mo-99 beta minus decay. Mo-99 has often been produced in a high- flux nuclear reactor through radioactive neutron capture reactions on Mo-98. The present paper provides a preliminary design of a toroidal transmutation system (TTS) based on a toroidal compact deuteron accelerator, which can provide the Mo-98 transmutation into Mo-99. This system is essentially composed of a multi-aperture plasma electrode and a target, submitted to 180 kV, where a positive deuteron beam is accelerated toward a titanium-target loaded with deuterium in which nuclear d-d fusion reactions are induced. The Particle Studio package of the Computer Simulation Technology (CST) software was applied to design, simulate and optimize the deuteron beam on the target. MCNP code provided to neutronic analysis. Based on electromagnetic and neutronic simulations, the neutron yield and reaction rates were estimated. The simulated data allowed appraising the Mo-99 activity. A TTS, in a specific configuration, could produce a total deuterium current of 1.6 A at the target and a neutron yield of 10{sup 13} n.s{sup -1}. In a arrangement of 30 column samples, TTS provides 230 mCi s{sup -1} Mo{sup 99} in each column, which represents 80% of Tc-99m in secular equilibrium. As conclusion, the system holds potential for generating Mo-99 and Tc-99m in a suitable activity in secular equilibrium. (author)

Toroidal deuteron accelerator for Mo-98 neutron activation

International Nuclear Information System (INIS)

Araujo, Wagner L.; Campos, Tarcisio P.R. Universidade Federal de Minas Gerais

2017-01-01

The radionuclide Tc- 99m is the most useful radioisotope in nuclear medicine. It can be produced by the Mo-99 beta minus decay. Mo-99 has often been produced in a high- flux nuclear reactor through radioactive neutron capture reactions on Mo-98. The present paper provides a preliminary design of a toroidal transmutation system (TTS) based on a toroidal compact deuteron accelerator, which can provide the Mo-98 transmutation into Mo-99. This system is essentially composed of a multi-aperture plasma electrode and a target, submitted to 180 kV, where a positive deuteron beam is accelerated toward a titanium-target loaded with deuterium in which nuclear d-d fusion reactions are induced. The Particle Studio package of the Computer Simulation Technology (CST) software was applied to design, simulate and optimize the deuteron beam on the target. MCNP code provided to neutronic analysis. Based on electromagnetic and neutronic simulations, the neutron yield and reaction rates were estimated. The simulated data allowed appraising the Mo-99 activity. A TTS, in a specific configuration, could produce a total deuterium current of 1.6 A at the target and a neutron yield of 10 13 n.s -1 . In a arrangement of 30 column samples, TTS provides 230 mCi s -1 Mo 99 in each column, which represents 80% of Tc-99m in secular equilibrium. As conclusion, the system holds potential for generating Mo-99 and Tc-99m in a suitable activity in secular equilibrium. (author)

An important step for the ATLAS toroid magnet

CERN Multimedia

2000-01-01

The ATLAS experiment's prototype toroid coil arrives at CERN from the CEA laboratory in Saclay on 6 October. The world's largest superconducting toroid magnet is under construction for the ATLAS experiment. A nine-metre long fully functional prototype coil was delivered to CERN at the beginning of October and has since been undergoing tests in the West Area. Built mainly by companies in France and Italy under the supervision of engineers from the CEA-Saclay laboratory near Paris and Italy's INFN-LASA, the magnet is a crucial step forward in the construction of the ATLAS superconducting magnet system. Unlike any particle detector that has gone before, the ATLAS detector's magnet system consists of a large toroidal system enclosing a small central solenoid. The barrel part of the toroidal system will use eight toroid coils, each a massive 25 metres in length. These will dwarf the largest toroids in the world when ATLAS was designed, which measure about six metres. So the ATLAS collaboration decided to build a...

Video Toroid Cavity Imager

Energy Technology Data Exchange (ETDEWEB)

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

2004-08-10

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

Optical design of grazing incidence toroidal grating monochromator

International Nuclear Information System (INIS)

Pouey, M.; Howells, M.R.; Takacs, P.Z.

1982-01-01

Design rules using geometrical optics and physical optics associated with the phase balancing method are discussed for stigmatic toroidal grazing incidence monochromators. To determine the optical performance of devices involving mirrirs and/or gratings, ray tracing programs using exact geometry are quite widely used. It is then desirable to have some way to infer the practical performance of an instrument from a spot diagram created by tracing a limited number of rays. We propose a first approach to this problem involving an estimation of the geometrical intensity distribution in the image plane and the corresponding line spread function. (orig.)

LASL toroidal reversed-field pinch program

International Nuclear Information System (INIS)

Baker, D.A.; Buchenauer, C.J.; Burkhardt, L.C.

1978-01-01

The determination of the absolute energy loss due to radiation from impurities in the LASL toroidal reversed-field pinch experiment ZT-S is reported. The measurements show over half of the energy loss is accounted for by this mechanism. Thomson scattering electron density measurements indicate only a gradual increase in temperature as the filling pressure is reduced indicating an increased energy loss at lower pressures. Cylindrical and toroidal simulations of the experiment indicate either that a highly radiative pinch boundary or anomalous transport are needed to match the experimental results. New effects on the equilibrium due to plasma flows induced by the toroidal geometry are predicted by the toroidal simulations. The preliminary results on the low temperature discharge cleaning of the ZT-S torus are reported. A description of the upgrade of the ZT-S experiment and the objectives, construction and theoretical predictions for the new ZT-40 experiment are given

Investigations of toroidal wave numbers of the kink instabilities in a toroidal pinch plasma

International Nuclear Information System (INIS)

Hamajima, Takataro; Irisawa, Juichi; Tsukada, Tokuaki; Sugito, Osamu; Maruyama, Hideaki

1979-01-01

The axial toroidal wave numbers of the kink instability of toroidal pinch plasma were measured and investigated with a specially designed coil, and the results were compared with the MHD theory. The schematic figure and the particulars of the experimental apparatus are briefly illustrated in the first part. The method of generating theta-Z pinch plasma, the wave form of the magnetic flux density in Z-direction and the plasma current are also explained. The 360 deg stereoscopic framing photographs were taken with an image converter camera at the intervals of 0.5 μs after the initiation of the main electric discharge in Z-circuit. From these photographs, the growth of the kink instability was observed. The measured magnetic field distribution at t = 2 μs is presented. In the second part, the radial displacement of plasma and toroidal wave number were measured from the above framing photographs. Then the spectra of plasma displacement were analyzed by the Fourier analysis. The measured results of toroidal wave number was analyzed by both the skin current model and the diffuse current model. Many new results obtained from the present study were mainly derived from the observation of the framing photographs, and they are summarized in the final part of this paper. (Aoki, K.)

Particle and impurity control in toroidal fusion devices

International Nuclear Information System (INIS)

Wootton, A.J.

1986-01-01

A review of working particle and impurity control techniques used in and proposed for magnetic fusion devices is presented. The requirements of both present-day machines and envisaged fusion reactors are considered. The various techniques which have been proposed are characterized by whether they affect sources, sinks, or fluxes; in many cases a particular method or device can appear in more than one category. Examples are drawn from published results. The solutions proposed for the large devices which will be operating during the next 5 years are discussed

Temperature effects on the magnetic properties of silicon-steel sheets using standardized toroidal frame.

Science.gov (United States)

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.

The SSC superconducting air core toroid design development

International Nuclear Information System (INIS)

Fields, T.; Carroll, A.; Chiang, I.H.; Frank, J.S.; Haggerty, J.; Littenberg, L.; Morse, W.; Strand, R.C.; Lau, K.; Weinstein, R.; McNeil, R.; Friedman, J.; Hafen, E.; Haridas, P.; Kendall, H.W.; Osborne, L.; Pless, I.; Rosenson, L.; Pope, B.; Jones, L.W.; Luton, J.N.; Bonanos, P.; Marx, M.; Pusateri, J.A.; Favale, A.; Gottesman, S.; Schneid, E.; Verdier, R.

1990-01-01

Superconducting air core toroids show great promise for use in a muon spectrometer for the SSC. Early studies by SUNY at Stony Brook funded by SSC Laboratory, have established the feasibility of building magnets of the required size. The toroid spectrometer consists of a central toroid with two end cap toroids. The configuration under development provides for muon trajectory measurement outside the magnetic volume. System level studies on support structure, assembly, cryogenic material selection, and power are performed. Resulting selected optimal design and assembly is described. 4 refs., 6 figs

Form factor of some types of toroidal solenoids

International Nuclear Information System (INIS)

Koryavko, V.I.; Litvinenko, Yu.A.

1979-01-01

Obtained were the type of dependence between consumed power and formed field for toroidal helical-wound solenoids and the expression for the form factor analogous to the Fabry coefficient for cylindrical solenoids. Determined were optimum dimensions of the helical winding of ''forceless'' toroidal solenoids satisfying the condition of the formation of maximum field at minimum consumed power. Investigations also covered some types of conventional toroidal solenoids. Presented in the paper diagrams permitted to chose dimensions of the considered toroidal solenoids according to their consumed power and winding material volume

Grinding Inside A Toroidal Cavity

Science.gov (United States)

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.

LASL toroidal reversed-field pinch programme

International Nuclear Information System (INIS)

Baker, D.A.; Buchenauer, C.J.; Burkhardt, L.C.

1979-01-01

The determination of the absolute energy loss due to radiation from impurities in the LASL toroidal reversed-field pinch experiment ZT-S is reported. The measurements show that over half the energy loss is accounted for by this mechanism. Thomson-scattering electron density measurements indicate only a gradual increase in temperature as the filling pressure is reduced, indicating an increased energy loss at lower pressures. Cylindrical and toroidal simulations of the experiment indicate either that a highly radiative pinch boundary or anomalous transport is needed to match the experimental results. New effects on the equilibrium due to plasma flows induced by the toroidal geometry are predicted by the toroidal simulations. The preliminary results on the low-temperature discharge cleaning of the ZT-S torus are reported. A description of the upgrade of the ZT-S experiment and the objectives, construction and theoretical predictions for the new ZT-40 experiment are given. (author)

Toroidal helical quartz forming machine

International Nuclear Information System (INIS)

Hanks, K.W.; Cole, T.R.

1977-01-01

The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed

MHD equilibrium with toroidal rotation

International Nuclear Information System (INIS)

Li, J.

1987-03-01

The present work attempts to formulate the equilibrium of axisymmetric plasma with purely toroidal flow within ideal MHD theory. In general, the inertial term Rho(v.Del)v caused by plasma flow is so complicated that the equilibrium equation is completely different from the Grad-Shafranov equation. However, in the case of purely toroidal flow the equilibrium equation can be simplified so that it resembles the Grad-Shafranov equation. Generally one arbitrary two-variable functions and two arbitrary single variable functions, instead of only four single-variable functions, are allowed in the new equilibrium equations. Also, the boundary conditions of the rotating (with purely toroidal fluid flow, static - without any fluid flow) equilibrium are the same as those of the static equilibrium. So numerically one can calculate the rotating equilibrium as a static equilibrium. (author)

Superconducting toroidal field coil current densities for the TFCX

International Nuclear Information System (INIS)

Kalsi, S.S.; Hooper, R.J.

1985-04-01

A major goal of the Tokamak Fusion Core Experiment (TFCX) study was to minimize the size of the device and achieve lowest cost. Two key factors influencing the size of the device employing superconducting magnets are toroidal field (TF) winding current density and its nuclear heat load withstand capability. Lower winding current density requires larger radial build of the winding pack. Likewise, lower allowable nuclear heating in the winding requires larger shield thickness between the plasma and coil. In order to achieve a low-cost device, it is essential to maximize the winding's current density and nuclear heating withhstand capability. To meet the above objective, the TFCX design specification adopted as goals a nominal winding current density of 3500 A/cm 2 with 10-T peak field at the winding and peak nuclear heat load limits of 1 MW/cm 3 for the nominal design and 50 MW/cm 3 for an advanced design. This study developed justification for these current density and nuclear heat load limits

Advanced fuelling system for use as a burn control tool in a burning plasma device

Energy Technology Data Exchange (ETDEWEB)

Raman, R. [Washington Univ., Seattle, WA (United States)

2007-07-01

Steady-state Advanced Tokamak (AT) scenarios rely on optimized density and pressure profiles to maximize the bootstrap current fraction. Under this mode of operation, the fuelling system must deposit small amounts of fuel where it is needed, and as often as needed, so as to compensate for fuel losses, but not to adversely alter the established density and pressure profiles. Conventional fuelling methods have not demonstrated successful fuelling of ATtype discharges and may be incapable of deep fuelling long pulse ELM-free discharges in ITER. The capability to deposit fuel at any desired radial location within the tokamak would provide burn control capability through alteration of the density profile. The ability to peak the density profile would ease ignition requirements, while operating ITER with density profiles that are peaked would increase the fusion power output. An advanced fuelling system should also be capable of fuelling well past internal transport barriers. Compact Toroid (CT) fuelling [R. Raman, et al., 'Experimental demonstration of tokamak fuelling by compact toroid injection,' Nucl. Fusion, 37, 967 (1997)] has the potential to meet these needs, while simultaneously providing a source of toroidal momentum input. A CT is a selfcontained toroidal plasmoid with embedded magnetic fields. The 20 Hz injector consists of the formation region, compression, acceleration and transport regions. Fuel gas is puffed into the formation region, and a combination of magnetic field and electric current ionizes this gas and creates a self-contained plasma ring (the 'CT'). Then a fast current pulse compresses and accelerates the CT by electromagnetic forces. The accelerated CT will travel at a speed of over 30 cm/{mu}s and for reactors will create a particle inventory perturbation of < 1% per pulse. At this level of particle inventory perturbation, optimized density profiles will not be adversely perturbed. Experimental data needed for the design of

Toroidal visco-resistive magnetohydrodynamic steady states contain vortices

International Nuclear Information System (INIS)

Bates, J.W.; Montgomery, D.C.

1998-01-01

Poloidal velocity fields seem to be a fundamental feature of resistive toroidal magnetohydrodynamic (MHD) steady states. They are a consequence of force balance in toroidal geometry, do not require any kind of instability, and disappear in the open-quotes straight cylinderclose quotes (infinite aspect ratio) limit. If a current density j results from an axisymmetric toroidal electric field that is irrotational inside a torus, it leads to a magnetic field B such that ∇x(jxB) is nonvanishing, so that the Lorentz force cannot be balanced by the gradient of any scalar pressure in the equation of motion. In a steady state, finite poloidal velocity fields and toroidal vorticity must exist. Their calculation is difficult, but explicit solutions can be found in the limit of low Reynolds number. Here, existing calculations are generalized to the more realistic case of no-slip boundary conditions on the velocity field and a circular toroidal cross section. The results of this paper strongly suggest that discussions of confined steady states in toroidal MHD must include flows from the outset. copyright 1998 American Institute of Physics

The complex and unique ATLAS Toroid family

CERN Multimedia

2002-01-01

Big parts for the toroid magnets that will be used in the ATLAS experiment have been continuously arriving at CERN since March. These structures will create the largest superconducting toroid magnet ever.

Bow-shaped toroidal field coils

International Nuclear Information System (INIS)

Bonanos, P.

1981-05-01

Design features of Bow-Shaped Toroidal Field Coils are described and compared with circular and D shaped coils. The results indicate that bow coils can produce higher field strengths, store more energy and be made demountable. The design offers the potential for the production of ultrahigh toroidal fields. Included are representative coil shapes and their engineering properties, a suggested structural design and an analysis of a specific case

Professional Windows Embedded Compact 7

CERN Document Server

Phung, Samuel; Joubert, Thierry; Hall, Mike

2011-01-01

Learn to program an array of customized devices and solutions As a compact, highly efficient, scalable operating system, Windows Embedded Compact 7 (WEC7) is one of the best options for developing a new generation of network-enabled, media-rich, and service-oriented devices. This in-depth resource takes you through the benefits and capabilities of WEC7 so that you can start using this performance development platform today. Divided into several major sections, the book begins with an introduction and then moves on to coverage of OS design, application development, advanced application developm

Compact plane illumination plugin device to enable light sheet fluorescence imaging of multi-cellular organisms on an inverted wide-field microscope.

Science.gov (United States)

Guan, Zeyi; Lee, Juhyun; Jiang, Hao; Dong, Siyan; Jen, Nelson; Hsiai, Tzung; Ho, Chih-Ming; Fei, Peng

2016-01-01

We developed a compact plane illumination plugin (PIP) device which enabled plane illumination and light sheet fluorescence imaging on a conventional inverted microscope. The PIP device allowed the integration of microscope with tunable laser sheet profile, fast image acquisition, and 3-D scanning. The device is both compact, measuring approximately 15 by 5 by 5 cm, and cost-effective, since we employed consumer electronics and an inexpensive device molding method. We demonstrated that PIP provided significant contrast and resolution enhancement to conventional microscopy through imaging different multi-cellular fluorescent structures, including 3-D branched cells in vitro and live zebrafish embryos. Imaging with the integration of PIP greatly reduced out-of-focus contamination and generated sharper contrast in acquired 2-D plane images when compared with the stand-alone inverted microscope. As a result, the dynamic fluid domain of the beating zebrafish heart was clearly segmented and the functional monitoring of the heart was achieved. Furthermore, the enhanced axial resolution established by thin plane illumination of PIP enabled the 3-D reconstruction of the branched cellular structures, which leads to the improvement on the functionality of the wide field microscopy.

Mechanical Commissioning of the ATLAS Barrel Toroid Magnet

CERN Document Server

Foussat, A; Dudarev, A; Bajas, H; Védrine, P; Berriaud, C; Sun, Z; Sorbi, M

2008-01-01

ATLAS is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider. Its features include the 4 T Barrel Toroid magnet, the largest superconducting magnet (25 m long, 20 m diameter) that provides the magnetic field for the ATLAS muon spectrometer. The coils integrated at CERN, were tested individually at maximum current of 22 kA in 2005. Following the mechanical assembly of the Barrel Toroid in the ATLAS underground cavern, the test of the full Barrel Toroid was performed in October 2006. Further tests are foreseen at the end 2007 when the system will include the two End Cap Toroids (ECT). The paper gives an overview of the good mechanical test results achieved in comparison with model predictions and the experience gained in the mechanical behavior of the ATLAS Toroidal coils is discussed.

Start-up scenario of compact tori based on REB-injection developed in SPAC-group

International Nuclear Information System (INIS)

Ikuta, K.

1981-01-01

Quasi-static start-up of compact tori without toroidal field coil is reviewed thoroughly in a proposal of the S-1 spheromak. During the formation phase we should note that the rapid heat loss from the plasma will give a bad effect for the generation of the confinement configuration. In the case of fast start-up of the configuration plasma can safely pass over the dangerous state of the instability toward the desirable stable state with a bonus of producing hot plasma. By this reason it is intended to discuss a fast start-up scenario of the compact tori based on REB injection developed in SPAC group

Long-wavelength microinstabilities in toroidal plasmas

International Nuclear Information System (INIS)

Tang, W.W.; Rewoldt, G.

1993-01-01

Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

Toroidal high-spin isomers in the nucleus 304120

Science.gov (United States)

Staszczak, A.; Wong, Cheuk-Yin; Kosior, A.

2017-05-01

Background: Strongly deformed oblate superheavy nuclei form an intriguing region where the toroidal nuclear structures may bifurcate from the oblate spheroidal shape. The bifurcation may be facilitated when the nucleus is endowed with a large angular moment about the symmetry axis with I =Iz . The toroidal high-K isomeric states at their local energy minima can be theoretically predicted using the cranked self-consistent Skyrme-Hartree-Fock method. Purpose: We use the cranked Skyrme-Hartree-Fock method to predict the properties of the toroidal high-spin isomers in the superheavy nucleus 120304184. Method: Our method consists of three steps: First, we use the deformation-constrained Skyrme-Hartree-Fock-Bogoliubov approach to search for the nuclear density distributions with toroidal shapes. Next, using these toroidal distributions as starting configurations, we apply an additional cranking constraint of a large angular momentum I =Iz about the symmetry z axis and search for the energy minima of the system as a function of the deformation. In the last step, if a local energy minimum with I =Iz is found, we perform at this point the cranked symmetry- and deformation-unconstrained Skyrme-Hartree-Fock calculations to locate a stable toroidal high-spin isomeric state in free convergence. Results: We have theoretically located two toroidal high-spin isomeric states of 120304184 with an angular momentum I =Iz=81 ℏ (proton 2p-2h, neutron 4p-4h excitation) and I =Iz=208 ℏ (proton 5p-5h, neutron 8p-8h) at the quadrupole moment deformations Q20=-297.7 b and Q20=-300.8 b with energies 79.2 and 101.6 MeV above the spherical ground state, respectively. The nuclear density distributions of the toroidal high-spin isomers 120304184(Iz=81 ℏ and 208 ℏ ) have the maximum density close to the nuclear matter density, 0.16 fm-3, and a torus major to minor radius aspect ratio R /d =3.25 . Conclusions: We demonstrate that aligned angular momenta of Iz=81 ℏ and 208 ℏ arising from

Quench propagation and protection analysis of the ATLAS Toroids

OpenAIRE

Dudarev, A; Gavrilin, A V; ten Kate, H H J; Baynham, D Elwyn; Courthold, M J D; Lesmond, C

2000-01-01

The ATLAS superconducting magnet system consists of the Barrel Toroid, two End Cap Toroids and the Central Solenoid. However, the Toroids of eight coils each are magnetically separate systems to the Central Solenoid. The Toroids are electrically connected in series and energized by a single power supply. The quench protection system is based on the use of relatively small external dump resistances in combination with quench-heaters activated after a quench event detection to initiate the inte...

Physics aspects of the Compact Ignition Tokamak

International Nuclear Information System (INIS)

Post, D.; Bateman, G.; Houlberg, W.

1986-11-01

The Compact Ignition Tokamak (CIT) is a proposed modest-size ignition experiment designed to study the physics of alpha-particle heating. The basic concept is to achieve ignition in a modest-size minimum cost experiment by using a high plasma density to achieve the condition of ntau/sub E/ ∼ 2 x 10 20 sec m -3 required for ignition. The high density requires a high toroidal field (10 T). The high toroidal field allows a large plasma current (10 MA) which improves the energy confinement, and provides a high level of ohmic heating. The present CIT design also has a gigh degree of elongation (k ∼ 1.8) to aid in producing the large plasma current. A double null poloidal divertor and a pellet injector are part of the design to provide impurity and particle control, improve the confinement, and provide flexibility for impurity and particle control, improve the confinement, and provide flexibility for improving the plasma profiles. Since auxiliary heating is expected to be necessary to achieve ignition, 10 to 20 MW of Ion Cyclotron Radio Frequency (ICRF) is to be provided

Investigation of intrinsic toroidal rotation scaling in KSTAR

Science.gov (United States)

Yoo, J. W.; Lee, S. G.; Ko, S. H.; Seol, J.; Lee, H. H.; Kim, J. H.

2017-07-01

The behaviors of an intrinsic toroidal rotation without any external momentum sources are investigated in KSTAR. In these experiments, pure ohmic discharges with a wide range of plasma parameters are carefully selected and analyzed to speculate an unrevealed origin of toroidal rotation excluding any unnecessary heating sources, magnetic perturbations, and strong magneto-hydrodynamic activities. The measured core toroidal rotation in KSTAR is mostly in the counter-current direction and its magnitude strongly depends on the ion temperature divided by plasma current (Ti/IP). Especially the core toroidal rotation in the steady-state is well fitted by Ti/IP scaling with a slope of ˜-23, and the possible explanation of the scaling is compared with various candidates. As a result, the calculated offset rotation could not explain the measured core toroidal rotation since KSTAR has an extremely low intrinsic error field. For the stability conditions for ion and electron turbulences, it is hard to determine a dominant turbulence mode in this study. In addition, the intrinsic toroidal rotation level in ITER is estimated based on the KSTAR scaling since the intrinsic rotation plays an important role in stabilizing resistive wall modes for future reference.

Compact magnetic fusion systems

Energy Technology Data Exchange (ETDEWEB)

Linford, R.K.

1983-12-01

If the core (first wall, blanket, shield, and magnet coils) of fusion reactor systems could be made smaller in mass and volume for a given net electric power output than is usually predicted for the mainline tokamak/sup 1/ and mirror concepts, the cost of the technological development of the core and the construction of power plants might be significantly reduced. Although progress in plasma physics and engineering approaches should continue to yield improvements in reactor designs, certain physics features of the mainline concepts may prevent major reductions in the size of the core without straining the limits of technology. However, more than a factor of ten reduction in volume and mass of the core, at constant output power, may be possible for a class of toroidal confinement concepts in which the confining magnetic fields are supported more by currents flowing in the plasma than those in the external coils. In spite of this dramatic increase in power density (ratio of total thermal output power to the volume of the core), the design of compact systems need not rely on any materials requirements that are qualitatively more difficult than those proposed for the lower-power-density mainline fusion concepts. In some respects compact systems require less of an extension of existing technology, e.g. magnetics.

Compact magnetic fusion systems

International Nuclear Information System (INIS)

Linford, R.K.

1983-01-01

If the core (first wall, blanket, shield, and magnet coils) of fusion reactor systems could be made smaller in mass and volume for a given net electric power output than is usually predicted for the mainline tokamak 1 and mirror concepts, the cost of the technological development of the core and the construction of power plants might be significantly reduced. Although progress in plasma physics and engineering approaches should continue to yield improvements in reactor designs, certain physics features of the mainline concepts may prevent major reductions in the size of the core without straining the limits of technology. However, more than a factor of ten reduction in volume and mass of the core, at constant output power, may be possible for a class of toroidal confinement concepts in which the confining magnetic fields are supported more by currents flowing in the plasma than those in the external coils. In spite of this dramatic increase in power density (ratio of total thermal output power to the volume of the core), the design of compact systems need not rely on any materials requirements that are qualitatively more difficult than those proposed for the lower-power-density mainline fusion concepts. In some respects compact systems require less of an extension of existing technology, e.g. magnetics

Compact fusion reactors

CERN Multimedia

CERN. Geneva

2015-01-01

Fusion research is currently to a large extent focused on tokamak (ITER) and inertial confinement (NIF) research. In addition to these large international or national efforts there are private companies performing fusion research using much smaller devices than ITER or NIF. The attempt to achieve fusion energy production through relatively small and compact devices compared to tokamaks decreases the costs and building time of the reactors and this has allowed some private companies to enter the field, like EMC2, General Fusion, Helion Energy, Lawrenceville Plasma Physics and Lockheed Martin. Some of these companies are trying to demonstrate net energy production within the next few years. If they are successful their next step is to attempt to commercialize their technology. In this presentation an overview of compact fusion reactor concepts is given.

Toroidal confinement of non-neutral plasma - A new approach to high-beta equilibrium

International Nuclear Information System (INIS)

Yoshida, Z.; Ogawa, Y.; Morikawa, J.

2001-01-01

Departure from the quasi-neutral condition allows us to apply significant two-fluid effects that impart a new freedom to the design of high-performance fusion plasma. The self-electric field in a non-neutralized plasma induces a strong ExB-drift flow. A fast flow produces a large hydrodynamic pressure that can balance with the thermal pressure of the plasma. Basic concepts to produce a toroidal non-neutral plasma have been examined on the internal-conductor toroidal confinement device Proto-RT. A magnetic separatrix determines the boundary of the confinement region. Electrons describe chaotic orbits in the neighborhood of the magnetic null point on the separatrix. The chaos yields collisionless diffusion of electrons from the particle source (electron gun) towards the confinement region. Collisionless heating also occurs in the magnetic null region, which can be applied to produce a plasma. (author)

Rotating bubble and toroidal nuclei and fragmentation

International Nuclear Information System (INIS)

Royer, G.; Haddad, F.; Jouault, B.

1995-01-01

The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy-ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. The potential barriers standing in these exotic deformation paths are compared with the three dimensional and plane fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localised below the plane fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension. (author)

Interim report on the assessment of engineering issues for compact high-field ignition devices

International Nuclear Information System (INIS)

Flanagan, C.A.

1986-04-01

The engineering issues addressed at the workshop included the overall configuration, layout, and assembly; limiter and first-wall energy removal; magnet system structure design; fabricability; repairability; and costs. In performing the assessment, the primary features and characteristics of each concept under study were reviewed as representative of this class of ignition device. The emphasis was to understand the key engineering areas of concern for this class of device and deliberately not attempt to define an optimum design or to choose a best approach. The assessment concluded that compact ignition tokamaks, as represented by the three concepts under study, are feasible. A number of critical engineering issues were identified, and all appear to have tractable solutions. The engineering issues appear quite challenging, and to obtain increased confidence in the apparent design solutions requires completion of the next level of design detail, complemented by appropriate development programs and testing

Analysis of MHD equilibria by toroidal multipolar expansions

International Nuclear Information System (INIS)

Alladio, F.; Crisanti, F.

1986-01-01

The use of fully toroidal co-ordinates permits the two-dimensional problem of the axisymmetric plasma toroidal equilibrium to be reduced to the one-dimensional problem of determining a limited number of its toroidal multipolar moments. This has allowed the creation of a fast semi-analytic predictive equilibrium code that can be used in both free and fixed boundary conditions for plasmas with circular or mildly non-circular cross-section. The concept of toroidal multipoles is also particularly suitable for the analysis of experimental data from magnetic probe measurements and clarifies the conditions under which the plasma thermal and electrical self-inductances βsub(p) and lsub(i) can be estimated separately. Finally, the interpretation of the magnetic equilibrium measurements in terms of toroidal multipoles can directly provide the boundary conditions for a fast equilibrium reconstruction code. Examples of the application of such a code to the JET magnetic measurements are reported. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Goumiri, I. R. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Rowley, C. W. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Sabbagh, S. A. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Gates, D. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Boyer, M. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Andre, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kolemen, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Taira, K. [Florida State Univ, Dept Mech Engn, Tallahassee, FL USA.

2016-02-19

A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.

Linear theory of the tearing instability in axisymmetric toroidal devices

International Nuclear Information System (INIS)

Rogister, A.; Singh, R.

1988-08-01

We derive a very general kinetic equation describing the linear evolution of low m/l modes in axisymmetric toroidal plasmas with arbitrary cross sections. Included are: Ion sound, inertia, diamagnetic drifts, finite poloidal beta, and finite ion Larmor radius effects. Assuming the magnetic surfaces to form a set of nested tori with circular cross sections of shifted centers, and introducing adequate simplifications justified by our knowledge of experimental tokamak plasmas, we then obtain explicitely the sets of equations describing the coupling of the quasimodes 0/1, 1/1, 2/1, and, for m≥2, m/1, (m+1)/1. By keeping finite aspect ratio effects into account when calculating the jump of the derivative of the eigenfunction, it is shown that the theory can explain the rapid evolution, within one sawtooth period, of the growth rate of the sawteeth precursors from resistive values to magnetohydrodynamic ones. The characteristics thus theoretically required from current profiles in sawtoothing discharges have clearly been observed. Other aspects of the full theory could be relevant to the phenomenon of major disruptions. (orig.)

Compact stellarators as reactors

International Nuclear Information System (INIS)

Lyon, J.F.; Valanju, P.; Zarnstorff, M.C.; Hirshman, S.; Spong, D.A.; Strickler, D.; Williamson, D.E.; Ware, A.

2001-01-01

Two types of compact stellarators are examined as reactors: two- and three-field-period (M=2 and 3) quasi-axisymmetric devices with volume-average =4-5% and M=2 and 3 quasi-poloidal devices with =10-15%. These low-aspect-ratio stellarator-tokamak hybrids differ from conventional stellarators in their use of the plasma-generated bootstrap current to supplement the poloidal field from external coils. Using the ARIES-AT model with B max =12T on the coils gives Compact Stellarator reactors with R=7.3-8.2m, a factor of 2-3 smaller R than other stellarator reactors for the same assumptions, and neutron wall loadings up to 3.7MWm -2 . (author)

A Compact Kapton-based Inkjet Printed Multiband Antenna for Flexible Wireless Devices

KAUST Repository

Ahmed, Sana

2015-04-20

A low cost inkjet printed multiband antenna envisioned for integration into flexible and conformal mobile devices is presented. The antenna structure contains a novel triangular iterative design with coplanar waveguide (CPW) feed, printed on a Kapton polyimide-based flexible substrate with dimensions of 70 x 70 x 0.11 mm3. The antenna covers four wide frequency bands with measured impedance bandwidths of 54.4%, 14%, 23.5% and 17.2%, centered at 1.2, 2.0, 2.6 and 3.4 GHz, respectively, thus, enabling it to cover GSM 900, GPS, UMTS, WLAN, ISM, Bluetooth, LTE 2300/ 2500 and WiMAX standards. The antenna has omnidirectional radiation pattern with a maximum gain of 2.1 dBi. To characterize the flexibility of the antenna, the fabricated prototype is tested in convex and concave bent configurations for radii of 78mm and 59mm. The overall performance remains unaffected, except a minor shift of 20 MHz and 60 MHz in S11, for concave bending at both radii. The compact, lightweight and conformal design as well as multiband performance in bent configurations, proves the suitability of the antenna for future electronic devices.

Toroidal mode-conversion in the ICRF

International Nuclear Information System (INIS)

Jaun, A.; Hellsten, T.; Chiu, S.C.

1997-08-01

Mode-conversion is studied in the ion-cyclotron range of frequencies (ICRF) taking into account the toroidal geometry relevant for tokamaks. The global wavefields obtained using the gyrokinetic toroidal PENN code illustrate how the fast wave propagates to the neighborhood of the ion-ion hybrid resonance, where it is converted to a slow wave which deposits the wave energy through resonant interactions with the particles. The power deposition profiles obtained are dramatically different from the toroidal resonance absorption, showing that Budden's model is not a good approximation in the torus. Radially and poloidally localized wavefield structures characteristic of slow wave eigenmodes are predicted and could in experiments be driven to large amplitudes so as to interact efficiently with fast particles. (author) 5 figs., 1 tab., 48 refs

Compact Quantum Random Number Generator with Silicon Nanocrystals Light Emitting Device Coupled to a Silicon Photomultiplier

Science.gov (United States)

Bisadi, Zahra; Acerbi, Fabio; Fontana, Giorgio; Zorzi, Nicola; Piemonte, Claudio; Pucker, Georg; Pavesi, Lorenzo

2018-02-01

A small-sized photonic quantum random number generator, easy to be implemented in small electronic devices for secure data encryption and other applications, is highly demanding nowadays. Here, we propose a compact configuration with Silicon nanocrystals large area light emitting device (LED) coupled to a Silicon photomultiplier to generate random numbers. The random number generation methodology is based on the photon arrival time and is robust against the non-idealities of the detector and the source of quantum entropy. The raw data show high quality of randomness and pass all the statistical tests in national institute of standards and technology tests (NIST) suite without a post-processing algorithm. The highest bit rate is 0.5 Mbps with the efficiency of 4 bits per detected photon.

Electromagnetic force support for thermonuclear device

International Nuclear Information System (INIS)

Sugimoto, Makoto; Yoshida, Kiyoshi; Tachikawa, Nobuo; Omori, Junji.

1992-01-01

The device of the present invention certainly supports electromagnetic force exerted on toroidal magnetic field coils. That is, a pair of support members are disposed being abutted against each other between toroidal magnetic field coils disposed radially in the torus direction of a vacuum vessel. Both of the support members are connected under an insulative state by way of an insulative structural portion having an insulation key. In addition, each of the support members and each of the toroidal magnetic field coils are connected by electromagnetic force support portions having a metal taper key and a metal spacer and supporting the electromagnetic force. With such a constitution, the electromagnetic force exerted on the toroidal magnetic field coils is supported by the electromagnetic force support portion having the metal taper key and the metal spacer. As a result, stable electromagnetic force support can be attained. Further, since the insulative structural portion has the insulation key, it can be assembled easily. (I.S.)

Curvature driven instabilities in toroidal plasmas

International Nuclear Information System (INIS)

Andersson, P.

1986-11-01

The electromagnetic ballooning mode, the curvature driven trapped electron mode and the toroidally induced ion temperature gradient mode have been studies. Eigenvalue equations have been derived and solved both numerically and analytically. For electromagnetic ballooning modes the effects of convective damping, finite Larmor radius, higher order curvature terms, and temperature gradients have been investigated. A fully toroidal fluid ion model has been developed. It is shown that a necessary and sufficient condition for an instability below the MHD limit is the presence of an ion temperature gradient. Analytical dispersion relations giving results in good agreement with numerical solutions are also presented. The curvature driven trapped electron modes are found to be unstable for virtually all parameters with growth rates of the order of the diamagnetic drift frequency. Studies have been made, using both a gyrokinetic ion description and the fully toroidal ion model. Both analytical and numerical results are presented and are found to be in good agreement. The toroidally induced ion temperature gradients modes are found to have a behavior similar to that of the curvature driven trapped electron modes and can in the electrostatic limit be described by a simple quadratic dispersion equation. (author)

Transport and Dynamics in Toroidal Fusion Systems

Energy Technology Data Exchange (ETDEWEB)

Schnack, Dalton D

2006-05-16

This document reports the successful completion of the OFES Theory Milestone for FY2005, namely, Perform parametric studies to better understand the edge physics regimes of laboratory experiments. Simulate at increased resolution (up to 20 toroidal modes), with density evolution, late into the nonlinear phase and compare results from different types of edge modes. Simulate a single case including a study of heat deposition on nearby material walls. The linear stability properties and nonlinear evolution of Edge Localized Modes (ELMs) in tokamak plasmas are investigated through numerical computation. Data from the DIII-D device at General Atomics (http://fusion.gat.com/diii-d/) is used for the magnetohydrodynamic (MHD) equilibria, but edge parameters are varied to reveal important physical effects. The equilibrium with very low magnetic shear produces an unstable spectrum that is somewhat insensitive to dissipation coefficient values. Here, linear growth rates from the non-ideal NIMROD code (http://nimrodteam.org) agree reasonably well with ideal, i.e. non-dissipative, results from the GATO global linear stability code at low toroidal mode number (n) and with ideal results from the ELITE edge linear stability code at moderate to high toroidal mode number. Linear studies with a more realistic sequence of MHD equilibria (based on DIII-D discharge 86166) produce more significant discrepancies between the ideal and non-ideal calculations. The maximum growth rate for the ideal computations occurs at toroidal mode index n=10, whereas growth rates in the non-ideal computations continue to increase with n unless strong anisotropic thermal conduction is included. Recent modeling advances allow drift effects associated with the Hall electric field and gyroviscosity to be considered. A stabilizing effect can be observed in the preliminary results, but while the distortion in mode structure is readily apparent at n=40, the growth rate is only 13% less than the non-ideal MHD

Long-wavelength microinstabilities in toroidal plasmas

International Nuclear Information System (INIS)

Tang, W.M.; Rewoldt, G.

1993-01-01

Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Res. (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 29] L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

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

Science.gov (United States)

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.

Influence of toroidal rotation on tearing modes

Science.gov (United States)

Cai, Huishan; Cao, Jintao; Li, Ding

2017-10-01

Tearing modes stability analysis including toroidal rotation is studied. It is found that rotation affects the stability of tearing modes mainly through the interaction with resistive inner region of tearing mode. The coupling of magnetic curvature with centrifugal force and Coriolis force provides a perturbed perpendicular current, and a return parallel current is induced to affect the stability of tearing modes. Toroidal rotation plays a stable role, which depends on the magnitude of Mach number and adiabatic index Γ, and is independent on the direction of toroidal rotation. For Γ >1, the scaling of growth rate is changed for typical Mach number in present tokamaks. For Γ = 1 , the scaling keeps unchanged, and the effect of toroidal rotation is much less significant, compared with that for Γ >1. National Magnetic Confinement Fusion Science Program and National Science Foundation of China under Grants No. 2014GB106004, No. 2013GB111000, No. 11375189, No. 11075161 and No. 11275260, and Youth Innovation Promotion Association CAS.

Celebration for the ATLAS Barrel Toroid magnet

CERN Multimedia

2007-01-01

Representatives from Funding Agencies and Barrel Toroid Magnet Laboratories during the ceremony. From left to right: Jean Zinn-Justin (Head of DAPNIA/CEA/Saclay), CERN Director-General Robert Aymar, and Roberto Petronzio (President INFN).Allan Clark (DPNC University Geneva) and Enrique Fernandez (IFAE Barcelona) were among the guests visiting the ATLAS cavern. The barrel toroid is visible in the background. A celebration took place at Point 1 on 13 December to toast the recent powering-up of the ATLAS barrel toroid magnet to full field (Bulletin No. 47-48/06). About 70 guests were invited to attend, mainly composed of representatives from funding partners and key members of the laboratory management teams of the barrel toroid magnet, representing CEA France, INFN Italy, BMBF Germany, Spain, Sweden, Switzerland, Russia, JINR Dubna and CERN. An introductory speech by ATLAS spokesperson Peter Jenni the scene for evening. This was followed by the ATLAS magnet system project leader Herman Ten Kate's account of the...

Drift mode calculations for the Large Helical Device

International Nuclear Information System (INIS)

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

2000-01-01

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

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

International Nuclear Information System (INIS)

Schnack, D.D.

1994-01-01

In this document the author describes an extension of the spatial gridding techniques to an MHD model suitable for the description of the dynamics of toroidal fusion devices. Since the dominant MHD modes in these devices have relatively long toroidal wavelength, the toroidal coordinate is approximated with finite Fourier series. The unstructured, triangular mesh is used to describe the details of the poloidal geometry. With some exceptions, the hydrodynamic variables are treated in a manner analogous to that used in CFD. These quantities (mass, energy, and momentum) are volume based densities that satisfy scalar or vector conservation laws. The electromagnetic variables (the magnetic flux density B and the electric current density J) are area based densities that satisfy pseudo-vector conservation laws, and have no counterpart in fluid dynamics. These variables are also constrained to remain solenoidal. These quantities are represented on the triangular mesh in a new manner that is an extension of that used on rectangular, structured meshes. In this work the author has chosen to solve the primitive MHD equations in order to make the resulting codes and techniques more generally applicable to problems beyond the narrow scope of tokamak plasmas. The temporal stiffness problems inherent in this description of tokamak dynamics that motivate the reduced MHD model are addressed here with the semi-implicit method of time integration. Finally, the author remarks that, while the present work deals strictly with the MHD equations, other volume based fluid descriptions, such as diffusive transport could easily be adapted to these techniques and coupled with the description of the electromagnetic field presented here

Finite element and node point generation computer programs used for the design of toroidal field coils in tokamak fusion devices

International Nuclear Information System (INIS)

Smith, R.A.

1975-06-01

The structural analysis of toroidal field coils in Tokamak fusion machines can be performed with the finite element method. This technique has been employed for design evaluations of toroidal field coils on the Princeton Large Torus (PLT), the Poloidal Diverter Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR). The application of the finite element method can be simplified with computer programs that are used to generate the input data for the finite element code. There are three areas of data input where significant automation can be provided by supplementary computer codes. These concern the definition of geometry by a node point mesh, the definition of the finite elements from the geometric node points, and the definition of the node point force/displacement boundary conditions. The node point forces in a model of a toroidal field coil are computed from the vector cross product of the coil current and the magnetic field. The computer programs named PDXNODE and ELEMENT are described. The program PDXNODE generates the geometric node points of a finite element model for a toroidal field coil. The program ELEMENT defines the finite elements of the model from the node points and from material property considerations. The program descriptions include input requirements, the output, the program logic, the methods of generating complex geometries with multiple runs, computational time and computer compatibility. The output format of PDXNODE and ELEMENT make them compatible with PDXFORC and two general purpose finite element computer codes: (ANSYS) the Engineering Analysis System written by the Swanson Analysis Systems, Inc., and (WECAN) the Westinghouse Electric Computer Analysis general purpose finite element program. The Fortran listings of PDXNODE and ELEMENT are provided

Development of an extremely compact impedance-based wireless sensing device

International Nuclear Information System (INIS)

Overly, Timothy G S; Park, Gyuhae; Farinholt, Kevin M; Farrar, Charles R

2008-01-01

This paper describes the development of the next generation of an extremely compact, wireless impedance sensor node for use in structural health monitoring (SHM) and piezoelectric active-sensor self-diagnostics. The sensor node uses a recently developed, low-cost integrated circuit that can measure and record the electrical impedance of a piezoelectric transducer. The sensor node also integrates several components, including a microcontroller for local computing, telemetry for wirelessly transmitting data, multiplexers for managing up to seven piezoelectric transducers per node, energy harvesting and storage mediums, and a wireless triggering circuit into one package to truly realize a comprehensive, self-contained wireless active-sensor node for various SHM applications. It is estimated that the developed sensor node requires less than 60 mW of total power for measurement, computation, and transmission. In addition, the sensor node is equipped with active-sensor self-diagnostic capabilities that can monitor the condition of piezoelectric transducers used in SHM applications. The performance of this miniaturized device is compared to our previous results and its broader capabilities are demonstrated

The use of gamma ray computed tomography to investigate soil compaction due to core sampling devices

International Nuclear Information System (INIS)

Pires, Luiz F.; Arthur, Robson C.J.; Correchel, Vladia; Bacchi, Osny O.S.; Reichardt, Klaus; Brasil, Rene P. Camponez do

2004-01-01

Compaction processes can influence soil physical properties such as soil density, porosity, pore size distribution, and processes like soil water and nutrient movements, root system distribution, and others. Soil porosity modification has important consequences like alterations in results of soil water retention curves. These alterations may cause differences in soil water storage calculations and matrix potential values, which are utilized in irrigation management systems. Because of this, soil-sampling techniques should avoid alterations of sample structure. In this work soil sample compaction caused by core sampling devices was investigated using the gamma ray computed tomography technique. A first generation tomograph with fixed source-detector arrangement and translation/rotational movements of the sample was utilized to obtain the images. The radioactive source is 241 Am, with an activity of 3.7 GBq, and the detector consists of a 3 in. x 3 in. NaI(Tl) scintillation crystal coupled to a photomultiplier tube. Soil samples were taken from an experimental field utilizing cylinders 4.0 cm high and 2.6 cm in diameter. Based on image analyses it was possible to detect compacted regions in all samples next to the cylinder wall due to the sampling system. Tomographic unit profiles of the sample permitted to identify higher values of soil density for deeper regions of the sample, and it was possible to determine the average densities and thickness of these layers. Tomographic analyses showed to be a very useful tool for soil compaction characterization and presented many advantages in relation to traditional methods. (author)

Toroidal groups line bundles, cohomology and quasi-Abelian varieties

CERN Document Server

Kopfermann, Klaus

2001-01-01

Toroidal groups are the connecting link between torus groups and any complex Lie groups. Many properties of complex Lie groups such as the pseudoconvexity and cohomology are determined by their maximal toroidal subgroups. Quasi-Abelian varieties are meromorphically separable toroidal groups. They are the natural generalisation of the Abelian varieties. Nevertheless, their behavior can be completely different as the wild groups show.

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

International Nuclear Information System (INIS)

Benson, R.D.

1985-01-01

The helical field (HF) coils in the Advanced Toroidal Facility (ATF) device consist of a set of 24 identical segments connected to form a continuous pair of helical coils wrapped around a toroidal vacuum vessel. Each segment weighs approximately 1364 kg (3000 lb) and is composed of 14 water-cooled copper plate conductors bolted to a cast stainless steel structural support member with a T-shape cross section (known as the structural tee). The segment components are electrically insulated with Kapton adhesive tape, G-10, Tefzel, and rubber to withstand 2.5 kV. As a final insulator and structural support, the entire segment is vacuum impregnated with epoxy. This paper offers a brief overview of the processes used to assemble the component parts into a completed segment, including identification of items that required special attention. 4 figs

Toroidal field ripple effects in large tokamaks

International Nuclear Information System (INIS)

Uckan, N.A.; Tsang, K.T.; Callen, J.D.

1975-01-01

In an experimental power reactor, the ripple produced by the finite number of toroidal field coils destroys the ideal axisymmetry of the configuration and is responsible for additional particle trapping, loss regions and plasma transport. The effects of toroidal field ripple on the plasma transport coefficient, the loss of alpha particles and energetic injection ions, and the relaxation of toroidal flows are investigated in a new and systematic way. The relevant results are applied to the ORNL-EPR reference design; the maximum ripple there of about 2.2 percent at the outer edge of the plasma column is found to be tolerable from plasma physics considerations

Prandtl number of toroidal plasmas

International Nuclear Information System (INIS)

Itoh, K.; Itoh, S.; Fukuyama, A.; Yagi, M.; Azumi, M.

1993-06-01

Theory of the L-mode confinement in toroidal plasmas is developed. The Prandtl number, the ratio between the ion viscosity and the thermal conductivity is obtained for the anomalous transport process which is caused by the self-sustained turbulence in the toroidal plasma. It is found that the Prandtl number is of order unity both for the ballooning mode turbulence in tokamaks and for the interchange mode turbulence in helical system. The influence on the anomalous transport and fluctuation level is evaluated. Hartmann number and magnetic Prandtl number are also discussed. (author)

Spherical tokamak without external toroidal fields

International Nuclear Information System (INIS)

Kaw, P.K.; Avinash, K.; Srinivasan, R.

2001-01-01

A spherical tokamak design without external toroidal field coils is proposed. The tokamak is surrounded by a spheromak shell carrying requisite force free currents to produce the toroidal field in the core. Such equilibria are constructed and it is indicated that these equilibria are likely to have robust ideal and resistive stability. The advantage of this scheme in terms of a reduced ohmic dissipation is pointed out. (author)

Compact Quantum Random Number Generator with Silicon Nanocrystals Light Emitting Device Coupled to a Silicon Photomultiplier

Directory of Open Access Journals (Sweden)

Zahra Bisadi

2018-02-01

Full Text Available A small-sized photonic quantum random number generator, easy to be implemented in small electronic devices for secure data encryption and other applications, is highly demanding nowadays. Here, we propose a compact configuration with Silicon nanocrystals large area light emitting device (LED coupled to a Silicon photomultiplier to generate random numbers. The random number generation methodology is based on the photon arrival time and is robust against the non-idealities of the detector and the source of quantum entropy. The raw data show high quality of randomness and pass all the statistical tests in national institute of standards and technology tests (NIST suite without a post-processing algorithm. The highest bit rate is 0.5 Mbps with the efficiency of 4 bits per detected photon.

Progress in gyrokinetic simulations of toroidal ITG turbulence

International Nuclear Information System (INIS)

Nevins, W.M.; Dimits, A.M.; Cohen, B.I.; Shumaker, D.E.

2001-01-01

The 3-D nonlinear toroidal gyrokinetic simulation code PG3EQ is used to study toroidal ion temperature gradient (ITG) driven turbulence - a key cause of the anomalous transport that limits tokamak plasma performance. Systematic studies of the dependence of ion thermal transport on various parameters and effects are presented, including dependence on E-vectorxB-vector and toroidal velocity shear, sensitivity to the force balance in simulations with radial temperature gradient variation, and the dependences on magnetic shear and ion temperature gradient. (author)

Matter in the form of toroidal electromagnetic vortices

Science.gov (United States)

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

A steady-state axisymmetric toroidal system

International Nuclear Information System (INIS)

Hirano, K.

1984-01-01

Conditions for achieving a steady state in an axisymmetric toroidal system are studied with emphasis on a very-high-beta field-reversed configuration. The analysis is carried out for the electromotive force produced by the Ohkawa current that is induced by neutral-beam injection. It turns out that, since the perpendicular component of the current j-vectorsub(perpendicular) to the magnetic field can be generated automatically by the diamagnetic effect, only the parallel component j-vectorsub(parallel) must be driven by the electromotive force. The drive of j-vectorsub(parallel) generates shear in the field line so that the pure toroidal field on the magnetic axis is rotated towards the plasma boundary and matched to the external field lines. This matching condition determines the necessary amount of injection beam current and power. It is demonstrated that a very-high-beta field-reversed configuration requires only a small amount of current-driving beam power because almost all the toroidal current except that close to the magnetic axis is carried by the diamagnetic current due to high beta. A low-beta tokamak, on the other hand, needs very high current-driving power since most of the toroidal current is composed of j-vectorsub(parallel) which must be driven by the beam. (author)

Toroidal vortices in resistive magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Montgomery, D.; Bates, J.W.; Li, S.

1997-01-01

When a time-independent electric current flows toroidally in a uniform ring of electrically conducting fluid, a Lorentz force results, jxB, where j is the local electric current density, and B is the magnetic field it generates. Because of purely geometric effects, the curl of jxB is nonvanishing, and so jxB cannot be balanced by the gradient of any scalar pressure. Taking the curl of the fluid close-quote s equation of motion shows that the net effect of the jxB force is to generate toroidal vorticity. Allowed steady states necessarily contain toroidal vortices, with flows in the poloidal directions. The flow pattern is a characteristic open-quotes double smoke ringclose quotes configuration. The effect seems quite general, although it is analytically simple only in special limits. One limit described here is that of high viscosity (low Reynolds number), with stress-free wall boundary conditions on the velocity field, although it is apparent that similar mechanical motions will result for no-slip boundaries and higher Reynolds numbers. A rather ubiquitous connection between current-carrying toroids and vortex rings seems to be implied, one that disappears in the open-quotes straight cylinderclose quotes limit. copyright 1997 American Institute of Physics

PDX toroidal field coils stress analysis

International Nuclear Information System (INIS)

Nikodem, Z.D.; Smith, R.A.

1975-01-01

A method used in the stress analysis of the PDX toroidal field coil is developed. A multilayer coil design of arbitrary dimensions in the shape of either a circle or an oval is considered. The analytical model of the coil and the supporting coil case with connections to the main support structure is analyzed using the finite element technique. The three dimensional magnetic fields and the non-uniform body forces which are a loading condition on a coil due to toroidal and poloidal fields are calculated. The method of analysis permits rapid and economic evaluations of design changes in coil geometry as well as in coil support structures. Some results pertinent to the design evolution and their comparison are discussed. The results of the detailed stress analysis of the final coil design due to toroidal field, poloidal field and temperature loads are presented

System design of toroidal field power supply of CDD tokamak

Energy Technology Data Exchange (ETDEWEB)

Liu, Zheng Zhi

1996-12-01

This report deals with system design of Toroidal Field Power Supply of CDD tokamak (CDD-TFPS). The general design philosophy and design variations are introduced. After the outline of CDD-TFPS, the short-circuit calculation, the evaluation of converter parameters, the compatibility of converter and line are carried out. the specifications of major components, semi-conductor devices and accessories are given. High attention is paid to protection system. The design of sub-control and grounding system are described too. Some more general material for power supply design are attached in appendices for reference. (author). 30 tabs., 21 figs.

System design of toroidal field power supply of CDD tokamak

International Nuclear Information System (INIS)

Liu, Zheng Zhi.

1996-12-01

This report deals with system design of Toroidal Field Power Supply of CDD tokamak (CDD-TFPS). The general design philosophy and design variations are introduced. After the outline of CDD-TFPS, the short-circuit calculation, the evaluation of converter parameters, the compatibility of converter and line are carried out. the specifications of major components, semi-conductor devices and accessories are given. High attention is paid to protection system. The design of sub-control and grounding system are described too. Some more general material for power supply design are attached in appendices for reference. (author). 30 tabs., 21 figs

Microfabricated Air-core Toroidal Inductor In Very High Frequency Power Converters

DEFF Research Database (Denmark)

Lê Thanh, Hoà; Nour, Yasser; Han, Anpan

2018-01-01

Miniaturization of power supplies is required for future intelligent electronic systems e.g. internet of things devices. Inductors play an essential role, and they are by far the most bulky and expensive components in power supplies. This paper presents a miniaturized microelectromechanical systems...... (MEMS) inductor and its performance in a very high frequency (VHF) power converter. The MEMS inductor is a siliconembedded air-core toroidal inductor, and it is constructed with through-silicon vias, suspended copper windings, silicon fixtures, and a silicon support die. The air-core inductors...

Compact tokamak reactors. Part 1 (analytic results)

International Nuclear Information System (INIS)

Wootton, A.J.; Wiley, J.C.; Edmonds, P.H.; Ross, D.W.

1996-01-01

We discuss the possible use of tokamaks for thermonuclear power plants, in particular tokamaks with low aspect ratio and copper toroidal field coils. Three approaches are presented. First we review and summarize the existing literature. Second, using simple analytic estimates, the size of the smallest tokamak to produce an ignited plasma is derived. This steady state energy balance analysis is then extended to determine the smallest tokamak power plant, by including the power required to drive the toroidal field, and considering two extremes of plasma current drive efficiency. The analytic results will be augmented by a numerical calculation which permits arbitrary plasma current drive efficiency; the results of which will be presented in Part II. Third, a scaling from any given reference reactor design to a copper toroidal field coil device is discussed. Throughout the paper the importance of various restrictions is emphasized, in particular plasma current drive efficiency, plasma confinement, plasma safety factor, plasma elongation, plasma beta, neutron wall loading, blanket availability and recirculating electric power. We conclude that the latest published reactor studies, which show little advantage in using low aspect ratio unless remarkably high efficiency plasma current drive and low safety factor are combined, can be reproduced with the analytic model

Escape of magnetic toroids from the Sun

International Nuclear Information System (INIS)

Bieber, John W.; Rust, David M.

1996-01-01

Analysis of heliospheric magnetic fields at 1 AU shows that 10 24 Mx of net toroidal flux escapes from the Sun per solar cycle. This rate is compared with the apparent rate of flux emergence at the solar surface, and it is concluded that escaping toroids will remove at least 20% of the emerging flux, and may remove as much as 100% of emerging flux if multiple eruptions occur on the toroids. The data imply that flux escapes the Sun with an efficiency far exceeding Parker's upper limit estimate of 3%. Toroidal flux escape is almost certainly the source of the observed overwinding of the interplanetary magnetic field spiral. Two mechanisms to facilitate net flux escape are discussed: helicity charging to push open the fields and flux transport with reconnection to close them off. We estimate the Sun will shed ∼2x10 45 Mx 2 of magnetic helicity per solar cycle, leading to a mean helicity density of 100 Mx 2 cm -3 at 1 AU, which agrees well with observations

Laser-induced production of large carbon-based toroids

International Nuclear Information System (INIS)

Lyn, M. Elizabeth; He Jibao; Koplitz, Brent

2005-01-01

We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C 60 , 22% C 70 ). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2-0.3 μm with tubular diameters of ∼50-100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures

Activation analysis of the compact ignition tokamak

International Nuclear Information System (INIS)

Selcow, E.C.

1986-01-01

The US fusion program has completed the conceptual design of a compact tokamak device that achieves ignition. The high neutron wall loadings associated with this compact deuterium-tritium-burning device indicate that radiation-related issues may be significant considerations in the overall system design. Sufficient shielding will be requied for the radiation protection of both reactor components and occupational personnel. A close-in igloo shield has been designed around the periphery of the tokamak structure to permit personnel access into the test cell after shutdown and limit the total activation of the test cell components. This paper describes the conceptual design of the igloo shield system and discusses the major neutronic concerns related to the design of the Compact Ignition Tokamak

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

International Nuclear Information System (INIS)

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

1982-09-01

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

Electrostatics of a Family of Conducting Toroids

Science.gov (United States)

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…

Current drive by neutral beams, rotating magnetic fields and helicity injection in compact toroids

International Nuclear Information System (INIS)

Farengo, R.

2002-01-01

A Monte-Carlo code is used to study neutral beam current drive in Spheromaks. The exact particle trajectories are followed in the self-consistent equilibria calculated including the beam current. Reducing Z(eff) does not increase the current drive efficiency because the reduction of the stopping cross section is compensated by an increase in the electron canceling current. Significant changes in the safety factor profile can be produced with relatively low beam currents. Minimum dissipation states of a flux core spheromak sustained by helicity injection are presented. Helicity balance is used as a constraint and the resistivity is considered to be non-uniform. Two types of relaxed states are found; one has a central core of open flux surrounded by a toroidal region of closed flux surfaces and the other has the open flux wrapped around the closed flux surfaces. Non-uniform resistivity effects can be very important due to the changes they produce in the safety factor profile. A hybrid, fluid electrons particle ions, code is employed to study ion dynamics in FRCs sustained by rotating magnetic fields. (author)

Structure of DNA toroids and electrostatic attraction of DNA duplexes

International Nuclear Information System (INIS)

Cherstvy, A G

2005-01-01

DNA-DNA electrostatic attraction is considered as the driving force for the formation of DNA toroids in the presence of DNA condensing cations. This attraction comes from the DNA helical charge distribution and favours hexagonal toroidal cross-sections. The latter is in agreement with recent cryo-electron microscopy studies on DNA condensed with cobalt hexammine. We treat the DNA-DNA interactions within the modern theory of electrostatic interaction between helical macromolecules. The size and thickness of the toroids is calculated within a simple model; other models of stability of DNA toroids are discussed and compared

Calculation of a toroidal labyrinth shields

International Nuclear Information System (INIS)

Sul'kin, A.G.

1979-01-01

Calculation of protective case with a toroidal labyrinth channel, being one of the main design elements of hose gamma-devices, is presented. The case provides relative isotropic distribution of radiation outside protection limits. The main geometric parameters of the channel are determined: r-radius of the channel hole, rho-bend radius of the channel axis, β-angle of the channel bend. General exposure dose rate of γ-radiation in the detection point at l distance (usually l=100 m during calculations), is also calculated. Differential current dose albedo values have been found for certain combinations of parameters of the labyrinth channel. It is considered for simplification of labyrinth channel calculations, that backward radiation scattering passes, without energy change and isotropically, due to which differential current albedo values of γ-radiation for any incidence angle may be determined from integral albedo current values by the empirie formula

Self-sustained turbulence and L-mode confinement in toroidal plasmas

International Nuclear Information System (INIS)

Itoh, K.; Itoh, S.; Fukuyama, A.; Yagi, M.; Azumi, M.

1993-04-01

Theory of the L-mode confinement in toroidal plasmas is developed. The quantitative effect of the anomalous transport, which is caused by microscopic fluctuations, on the pressure-gradient- driven modes is analyzed. The ExB nonlinearity is renormalized in a form of the transport coefficient such as the thermal diffusivity, the ion viscosity and the current diffusivity. The destabilization by the current-diffusivity and the stabilization by the thermal transport and ion viscosity are analyzed. By use of the mean-field approximations, the nonlinear dispersion relation is solved. Growth rate and stability condition are expressed in terms of the renormalized transport coefficients. The transport coefficients in the steady state are obtained by the marginal stability condition for the least stable mode. This method is applied to the microscopic ballooning mode for the toroidal plasma with the magnetic well (such as tokamak). The comparison with experimental observations are made. A good agreement is found in a various aspects of the L-mode plasmas; The typical wavenumber and level of the fluctuations for the self-sustained turbulence is also obtained. The analysis is also made for the plasma with magnetic hill and shear (such as torsatron/Heliotron devices). This method is applied to the interchange modes. Formula of the anomalous transport is obtained. Also investigated is the case of the magnetic well and low magnetic shear (conventional stellarator). The roles of the pressure gradient and the collisionless skin depth in determining the anomalous transport are found to be generic in toroidal plasmas. The difference in the magnetic configuration affects the transport coefficient. These formula explain major experimental observations. (J.P.N.)

Investigation of diocotron modes in toroidally trapped electron plasmas using non-destructive method

Science.gov (United States)

Lachhvani, Lavkesh; Pahari, Sambaran; Sengupta, Sudip; Yeole, Yogesh G.; Bajpai, Manu; Chattopadhyay, P. K.

2017-10-01

Experiments with trapped electron plasmas in a SMall Aspect Ratio Toroidal device (SMARTEX-C) have demonstrated a flute-like mode represented by oscillations on capacitive (wall) probes. Although analogous to diocotron mode observed in linear electron traps, the mode evolution in toroids can have interesting consequences due to the presence of in-homogeneous magnetic field. In SMARTEX-C, the probe signals are observed to undergo transition from small, near-sinusoidal oscillations to large amplitude, non-linear "double-peaked" oscillations. To interpret the wall probe signal and bring forth the dynamics, an expression for the induced current on the probe for an oscillating charge is derived, utilizing Green's Reciprocation Theorem. Equilibrium position, poloidal velocity of the charge cloud, and charge content of the cloud, required to compute the induced current, are estimated from the experiments. Signal through capacitive probes is thereby computed numerically for possible charge cloud trajectories. In order to correlate with experiments, starting with an intuitive guess of the trajectory, the model is evolved and tweaked to arrive at a signal consistent with experimentally observed probe signals. A possible vortex like dynamics is predicted, hitherto unexplored in toroidal geometries, for a limited set of experimental observations from SMARTEX-C. Though heuristic, a useful interpretation of capacitive probe data in terms of charge cloud dynamics is obtained.

Effect of toroidicity during lower hybrid mode conversion

International Nuclear Information System (INIS)

Riyopoulos, S.; Mahajan, S.

1985-11-01

The effect of toroidicity during lower hybrid mode conversion is examined by treating the wave propagation in an inhomogeneous medium as an eigenvalue problem for ω 2 (m,n),m,n poloidal and toroidal wave numbers. Since the frequency regime near ω 2 = ω/sub LH/ 2 is an accumulation point for the eigenvalue spectrum, the degenerate perturbation technique must be applied. The toroidal eigenmodes are constructed by a zeroth order superposition of monochromatic solutions with different poloidal dependence m, thus they generically exhibit a wide spectrum in k/sub parallel/ for given fixed ω 2 even for small inverse aspect ratio epsilon. In case that the average is in the neighborhood of k/sub min/, the minimum wave number for accessibility of the mode conversion regime, it is expected that excitation of toroidal modes rather than geometric optics will determine the wave coupling to the plasma

Commercial tokamak reactors with resistive toroidal field magnets

International Nuclear Information System (INIS)

Bombery, L.; Cohn, D.R.; Jassby, D.L.

1984-01-01

Scaling relations and design concepts are developed for commercial tokamak reactors that use watercooled copper toroidal field (TF) magnets. Illustrative parameters are developed for reactors that are scaled up in size from LITE test reactor designs, which use quasi-continuous copper plate magnets. Acceptably low magnet power requirements may be attainable in a moderate beta (β = 0.065) commercial reactor with a major radius of 6.2 m. The shielding thickness and magnet size are substantially reduced relative to values in commercial reactors with superconducting magnets. Operation at high beta (β = 0.14) leads to a reduction in reactor size, magnet-stored energy, and recirculating power. Reactors using resistive TF magnets could provide advantages of physically smaller devices, improved maintenance features, and increased ruggedness and reliability

Analysis of toroidal rotation data for the DIII-D tokamak

International Nuclear Information System (INIS)

St John, H.; Stroth, U.; Burrell, K.H.; Groebner, R.J.; DeBoo, J.C.; Gohil, P.

1989-01-01

Both poloidal and toroidal rotation are observed during routine neutral beam heating operation of the DIII-D tokamak. Poloidal rotation results and the empirical techniques used to measure toroidal and poloidal rotation speeds are described by Groebner. Here we concentrate on the analysis of recent measurements of toroidal rotation made during diverted, H-mode operation of the DIII-D tokamak during co- and counter-neutral beam injection of hydrogen into deuterium plasmas. Our results are based on numerical inversions using the transport code ONETWO, modified to account for the radial diffusion of toroidal angular momentum. 13 refs., 4 figs

Magnetic configuration dependence of the shafranov shift in the Large Helical Device

Energy Technology Data Exchange (ETDEWEB)

Kobuchi, T; Ida, K; Yamada, H; Yokoyama, M; Watanabe, K Y; Sakakibara, S; Yoshinuma, M [National Institute for Fusion Science, 322-6 Oroshi-Cho, Toki-City, 509-5292 (Japan)

2006-06-15

The dependence of the Shafranov shift on magnetic field configuration, toroidicity and central rotational transform {iota}(0) in neutral beam heated plasma has been experimentally investigated in the Large Helical Device. The toroidicity of the plasma is controlled by the quadrupole field, while the central {iota}(0) is controlled by changing the distance of the current centre of the helical coil to the plasma. It is experimentally confirmed that both the lower toroidicity and the higher {iota}(0) contribute to the reduction of the Shafranov shift as predicted by the three-dimensional equilibrium code, VMEC.

Study of an edge transport barrier by Langmuir probes in the compact helical system

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, M [Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603 (Japan); Toi, K [National Institute of Fusion Science, Toki 509-5292 (Japan); Nagaoka, K [National Institute of Fusion Science, Toki 509-5292 (Japan); Suzuki, C [National Institute of Fusion Science, Toki 509-5292 (Japan); Minami, T [National Institute of Fusion Science, Toki 509-5292 (Japan); Akiyama, T [National Institute of Fusion Science, Toki 509-5292 (Japan); Isobe, M [National Institute of Fusion Science, Toki 509-5292 (Japan); Yoshimura, Y [National Institute of Fusion Science, Toki 509-5292 (Japan); Nishimura, S [National Institute of Fusion Science, Toki 509-5292 (Japan); Shimizu, A [National Institute of Fusion Science, Toki 509-5292 (Japan); Takahashi, C [National Institute of Fusion Science, Toki 509-5292 (Japan); Matsuoka, K [National Institute of Fusion Science, Toki 509-5292 (Japan); Okamura, S [National Institute of Fusion Science, Toki 509-5292 (Japan)

2006-05-15

The edge transport barrier (ETB) produced by the L-H transition was measured by a triple Langmuir probe (LP) at two toroidal sections of the compact helical system (CHS), of which diagnostic method has good time and spatial resolutions. The radial profiles of electron density (n{sub e}), electron temperature (T{sub e}) and space potential (V{sub s}) in the ETB region have different shapes at two different toroidal sections. These profiles are deformed inside the ETB region at one location and are formed with rather smooth variations at the other. These deformations gradually disappear in the deep H-phase (after {approx}15 ms from the transition) and the profiles inside the ETB become similar at both sections. The deformation seems linked to the presence of a non-rotating magnetic island at the rational surface of the rotational transform {iota}/2{pi} = 1.

Trapped ion mode in toroidally rotating plasmas

International Nuclear Information System (INIS)

Artun, M.; Tang, W.M.; Rewoldt, G.

1995-04-01

The influence of radially sheared toroidal flows on the Trapped Ion Mode (TIM) is investigated using a two-dimensional eigenmode code. These radially extended toroidal microinstabilities could significantly influence the interpretation of confinement scaling trends and associated fluctuation properties observed in recent tokamak experiments. In the present analysis, the electrostatic drift kinetic equation is obtained from the general nonlinear gyrokinetic equation in rotating plasmas. In the long perpendicular wavelength limit k τ ρ bi much-lt 1, where ρ bi is the average trapped-ion banana width, the resulting eigenmode equation becomes a coupled system of second order differential equations nmo for the poloidal harmonics. These equations are solved using finite element methods. Numerical results from the analysis of low and medium toroidal mode number instabilities are presented using representative TFTR L-mode input parameters. To illustrate the effects of mode coupling, a case is presented where the poloidal mode coupling is suppressed. The influence of toroidal rotation on a TFTR L-mode shot is also analyzed by including a beam species with considerable larger temperature. A discussion of the numerical results is presented

ATLAS: Full power for the toroid magnet

CERN Multimedia

2006-01-01

The 9th of November was a memorable day for ATLAS. Just before midnight, the gigantic Barrel toroid magnet reached its nominal field of 4 teslas in the coil windings, with an electrical current of 21000 amperes (21 kA) passing through the eight superconducting coils (as seen on the graph). This achievement was obtained after several weeks of commissioning. The ATLAS Barrel Toroid was first cooled down for about six weeks in July-August to -269°C (4.8 K) and then powered up step-by-step in successive test sessions to 21 kA. This is 0.5 kA above the current required to produce the nominal magnetic field. Afterwards, the current was safely switched off and the stored magnetic energy of 1.1 gigajoules was dissipated in the cold mass, raising its temperature to a safe -218°C (55 K). 'We can now say that the ATLAS Barrel Toroid is ready for physics,' said Herman ten Kate, project leader for the ATLAS magnet system. The ATLAS barrel toroid magnet is the result of a close collaboration between the magnet la...

Neutron diffusion in spheroidal, bispherical, and toroidal systems

International Nuclear Information System (INIS)

Williams, M.M.R.

1986-01-01

The neutron flux has been studied around absorbing bodies of spheroidal, bispherical, and toroidal shapes in an infinite nonabsorbing medium. Exact solutions have been obtained by using effective boundary conditions at the surfaces of the absorbing bodies. The problems considered are as follows: 1. Neutron flux and current distributions around prolate and oblate spheroids. It is shown that an equivalent sphere approximation can lead to accurate values for the rate of absorption. 2. Neutron flux and current in a bispherical system of unequal spheres. Three separate situations arise here: (a) two absorbing spheres, (b) two spherical sources, and (c) one spherical source and one absorbing sphere. It is shown how the absorption rate in the two spheres depends on their separation. 3. Neutron flux and current in a toroidal system: (a) an absorbing toroid and (b) a toroidal source. The latter case simulates the flux distribution from a thermonuclear reactor vessel. Finally, a brief description of how these techniques can be extended to multiregion problems is given

Experimental investigation of plasma relaxation using a compact coaxial magnetized plasma gun in a background plasma

Science.gov (United States)

Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott; University of New Mexico Collaboration; Los Alamos National Laboratory Collaboration

2013-10-01

A compact coaxial plasma gun is employed for experimental studies of plasma relaxation in a low density background plasma. Experiments are being conducted in the linear HelCat device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes within the intergalactic medium. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5-10 kV and ~100 kA. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities ~1.2Cs and densities ~1020 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

Relativistic stars with purely toroidal magnetic fields

International Nuclear Information System (INIS)

Kiuchi, Kenta; Yoshida, Shijun

2008-01-01

We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The basic equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal magnetic fields are derived for the first time. To solve these basic equations numerically, we extend the Cook-Shapiro-Teukolsky scheme for calculating relativistic rotating stars containing no magnetic field to incorporate the effects of the purely toroidal magnetic fields. By using the numerical scheme, we then calculate a large number of the equilibrium configurations for a particular distribution of the magnetic field in order to explore the equilibrium properties. We also construct the equilibrium sequences of the constant baryon mass and/or the constant magnetic flux, which model the evolution of an isolated neutron star as it loses angular momentum via the gravitational waves. Important properties of the equilibrium configurations of the magnetized stars obtained in this study are summarized as follows: (1) For the nonrotating stars, the matter distribution of the stars is prolately distorted due to the toroidal magnetic fields. (2) For the rapidly rotating stars, the shape of the stellar surface becomes oblate because of the centrifugal force. But, the matter distribution deep inside the star is sufficiently prolate for the mean matter distribution of the star to be prolate. (3) The stronger toroidal magnetic fields lead to the mass shedding of the stars at the lower angular velocity. (4) For some equilibrium sequences of the constant baryon mass and magnetic flux, the stars can spin up as they lose angular momentum.

Pressing device for producing compacts from source material in powder form in particular pulverized nuclear reactor fuel

International Nuclear Information System (INIS)

Heller, G.; Adelmann, M.; Konigs, W.; Wendorf, W.

1984-01-01

Pressing device for producing compacts from source material in powder form, in particular pulverized nuclear reactor fuel having a die-plate contained in platen and a bore associated with a ram, for receiving source material powder, a filling shoe, and a reservoir for powder connected by a hose to the filling shoe. The device is characterized by a passing wheel in the filling shoe as filling aid means; a tube containing a feedscrew disposed between the reservoir and hose as metering means; the reservoir having a bottom part with a can type place-on part with an opening eccentric to the axis; a coupling part and a cover part are placed on the open part of the can, these parts are also provided with a passageway to the feedscrew eccentric to the longitudinal axis

Plasma transport in a compact ignition tokamak

International Nuclear Information System (INIS)

Singer, C.E.; Ku, L.P; Bateman, G.

1987-02-01

Nominal predicted plasma conditions in a compact ignition tokamak are illustrated by transport simulations using experimentally calibrated plasma transport models. The range of uncertainty in these predictions is explored by using various models which have given almost equally good fits to experimental data. Using a transport model which best fits the data, thermonuclear ignition occurs in a Compact Ignition Tokamak design with major radius 1.32 m, plasma half-width 0.43 m, elongation 2.0, and toroidal field and plasma current ramped in six seconds from 1.7 to 10.4 T and 0.7 to 10 MA, respectively. Ignition is facilitated by 20 MW of heating deposited off the magnetic axis near the 3 He minority cyclotron resonance layer. Under these conditions, sawtooth oscillations are small and have little impact on ignition. Tritium inventory is minimized by preconditioning most discharges with deuterium. Tritium is injected, in large frozen pellets, only after minority resonance preheating. Variations of the transport model, impurity influx, heating profile, and pellet ablation rates, have a large effect on ignition and on the maximum beta that can be achieved

Controlling Confinement with Induced Toroidal Current in the Flexible Heliac TJ-II

Energy Technology Data Exchange (ETDEWEB)

Romero, J A; Lopez-Bruna, D; Lopez-Fraguas, A; Ascasibar, E; TJ-II Team

2002-07-01

A method to control plasma particle an energy confinement in the TJ-II Heliac devices is reported A small toroidal current is induced in the plasma with the aid of a 0.2 Wb air core transformer. Plasma particle and energy confinement improve (degrade) with negative (positive) plasma current. For typical TJ-II discharges plasma density and temperature broaden considerably when plasma current is sufficiently negative, accounting for a 40% increase in stored energy. The experimental results agree qualitatively with the paradigm of instability growth rate modifications with magnetic shear. (Author) 18 refs.

Controlling Confinement with Induced Toroidal Current in the Flexible Heliac TJ-II

International Nuclear Information System (INIS)

Romero, J. A.; Lopez-Bruna, D.; Lopez-Fraguas, A.; Ascasibar, E.; TJ-II Team

2002-01-01

A method to control plasma particle an energy confinement in the TJ-II Heliac devices is reported A small toroidal current is induced in the plasma with the aid of a 0.2 Wb air core transformer. Plasma particle and energy confinement improve (degrade) with negative (positive) plasma current. For typical TJ-II discharges plasma density and temperature broaden considerably when plasma current is sufficiently negative, accounting for a 40% increase in stored energy. The experimental results agree qualitatively with the paradigm of instability growth rate modifications with magnetic shear. (Author) 18 refs

Performance of a Folded-Strip Toroidally Wound Induction Machine

DEFF Research Database (Denmark)

Jensen, Bogi Bech; Jack, Alan G.; Atkinson, Glynn J.

2011-01-01

This paper presents the measured experimental results from a four-pole toroidally wound induction machine, where the stator is constructed as a pre-wound foldable strip. It shows that if the machine is axially restricted in length, the toroidally wound induction machine can have substantially...... shorter stator end-windings than conventionally wound induction machines, and hence that a toroidally wound induction machine can have lower losses and a higher efficiency. The paper also presents the employed construction method, which emphasizes manufacturability, and highlights the advantages...

An interim report on the materials and selection criteria analysis for the Compact Ignition Tokamak Toroidal Field Coil Turn-to-Turn Insulation System

International Nuclear Information System (INIS)

Campbell, V.W.; Dooley, J.B.; Hubrig, J.G.; Janke, C.J.; McManamy, T.J.; Welch, D.E.

1990-01-01

Design criteria for the Compact Ignition Tokamak, Toroidal-Field (TF) Coil, Turn-to-Turn Insulation System require an insulation sheet and bonding system that will survive cryogenic cycling in a radiation environment and maintain structural integrity during exposure to the significant compressive and shear loads associated with each operating cycle. For thermosetting resin systems, a complex interactive dependency exists between optimum peak value, in-service property performance capabilities of candidate generic materials; key handling and processing parameters required to achieve their optimum in-service property performance as an insulation system; and suitability of their handling and processing parameters as a function of design configuration and assembly methodology. This dependency is assessed in a weighted study matrix in which two principal programmatic approaches for the development of the TF Coil Subassembly Insulation System have been identified. From this matrix study, two viable approaches to the fabrication of the insulation sheet were identified: use of a press-formed sheet bonded in place with epoxy for mechanical bonding and tolerance take-up and formation of the insulation sheet by placement of dry cloth and subsequent vacuum pressure impregnation. Laboratory testing was conducted to screen a number of combinations of resins and hardeners on a generic basis. These combinations were chosen for their performance in similar applications. Specimens were tested to screen viscosity, thermal-shock tolerance, and cryogenic tolerance. Cryogenic shock and cryogenic temperature proved to be extremely lethal to many combinations of resin, hardener, and cure. Two combinations survived: a heavily flexibilized bisphenol A resin with a flexibilized amine hardener and a bisphenol A resin with cycloaliphatic amine hardener. 7 refs., 12 figs., 6 tabs

Have it your way. A modular approach to custom compact control rooms

International Nuclear Information System (INIS)

Harmon, Daryl; Scarola, Ken

2003-01-01

In spite of the recent lack of growth in the nuclear power industry, a transition is taking place to compact main control rooms as the design of choice for power generating facilities. This is evident in the design and construction of new facilities, including Advanced Light Water Reactors such as the Korean Shin Kori 3 and 4 units, as well as Generation IV reactors. Also, compact control rooms are increasingly preferred for the modernization of current generation plants. This shift reflects that compact control rooms combine cost savings through equipment reduction and standardization with operability improvements through increased functionality and flexibility and improved presentation. Though compact control rooms feature significantly fewer Human Machine Interface (HMI) devices than their conventional counterparts, customers still require a wide variety of different configurations to accommodate their individual operations philosophies, cultural norms, licensing regulations and physical constraints. To meet this need, Westinghouse Electric Company has developed an innovative, modular approach to designing compact control rooms for nuclear power plants. This approach features a small set of standard HMI devices serving as building blocks for all compact control room functions. The building blocks include qualified and non-safety video devices for implementing displays, alarms, multi-channel soft controls, computerized procedures, etc. These building blocks can be used for (1) large screen overview displays, (2) console-based control and monitoring and (3) HMI devices for conventional, benchboard-style control panels. Their modular design allows these building blocks to be arranged in various physical configurations to meet a wide variety of customer's control room preferences and constraints. For example, a compact control room could use the qualified building blocks (1) to configure a dedicated safety panel independent of the normal operational consoles, or (2

Toroidal Plasma Thruster for Interplanetary and Interstellar Space Flights

International Nuclear Information System (INIS)

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

2001-01-01

This work involves a conceptual assessment for using the toroidal fusion reactor for deep space interplanetary and interstellar missions. Toroidal thermonuclear fusion reactors, such as tokamaks and stellarators, are unique for space propulsion, allowing for a design with the magnetic configuration localized inside toroidal magnetic field coils. Plasma energetic ions, including charged fusion products, can escape such a closed configuration at certain conditions, a result of the vertical drift in toroidal rippled magnetic field. Escaping particles can be used for direct propulsion (since toroidal drift is directed one way vertically) or to create and heat externally confined plasma, so that the latter can be used for propulsion. Deuterium-tritium fusion neutrons with an energy of 14.1 MeV also can be used for direct propulsion. A special design allows neutrons to escape the shield and the blanket of the tokamak. This provides a direct (partial) conversion of the fusion energy into the directed motion of the propellant. In contrast to other fusion concepts proposed for space propulsion, this concept utilizes the natural drift motion of charged particles out of the closed magnetic field configuration

Toroidal and rotating bubble nuclei and the nuclear fragmentation

International Nuclear Information System (INIS)

Royer, G.; Fauchard, C.; Haddad, F.; Jouault, B.

1997-01-01

The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. Previously, a one-parameter shape sequence has been defined to describe the path leading to pumpkin-like configurations and toroidal shapes. New analytical expressions for the shape dependent functions have been obtained. The potential barriers standing in these exotic deformation paths are compared with the three-dimensional and plane-fragmentation barriers. Metastable bubble-like minima only appear at very high angular momentum and above the three dimensional fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localized below the plane-fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension

Microscopic Description of Electric and Magnetic Toroidal Multipoles in Hybrid Orbitals

Science.gov (United States)

Hayami, Satoru; Kusunose, Hiroaki

2018-03-01

We derive the quantum-mechanical operator expressions of multipoles under the space-time inversion group. We elucidate that electric and magnetic toroidal multipoles, in addition to ordinary non-toroidal ones, are fundamental pieces to express arbitrary electronic degrees of freedom. We show that electric (magnetic) toroidal multipoles higher than the dipole (monopole) can become active in a hybridized-orbital system. We also demonstrate emergent cross-correlated couplings between the electric, magnetic, and elastic degrees of freedom, such as magneto-electric and magneto(electro)-elastic coupling, under toroidal multipole orders.

Discussion of discrete D shape toroidal coil

International Nuclear Information System (INIS)

Kaiho, Katsuyuki; Ohara, Takeshi; Agatsuma, Ko; Onishi, Toshitada

1988-01-01

A novel design for a toroidal coil, called the D shape coil, was reported by J. File. The coil conductors are in pure tension and then subject to no bending moment. This leads to a smaller number of emf supports in a simpler configuration than that with the conventional toroidal coil of circular cross-section. The contours of the D shape are given as solutions of a differential equation. This equation includes the function of the magnetic field distribution in the conductor region which is inversely proportional to the winding radius. It is therefore important to use the exact magnetic field distribution. However the magnetic field distribution becomes complicated when the D shape toroidal coil is comprised of discrete coils and also depends on the D shape configuration. A theory and a computer program for designing the practical pure-tension toroidal coil are developed. Using this computer code, D shape conductors are calculated for various numbers of discrete coils and the results are compared. Electromagnetic forces in the coils are also calculated. It is shown that the hoop stress in the conductors depends only on the total ampere-turns of the coil when the contours of the D shape are similar. (author)

Stationary magnetohydrodynamic equilibrium of toroidal plasma in rotation

International Nuclear Information System (INIS)

Missiato, O.

1986-01-01

The stationary equations of classical magnetohydrodynamics are utilized to study the toroidal motion of a thermonuclear magnetically - confined plasma with toroidal symmetry (Tokamak). In the present work, we considered a purely toroidal stationary rotation and te problem is reduced to studing a second order partial differencial equation of eliptic type Maschke-Perrin. Assuming that the temperature remains constant on the magnetic surfaces, an analitic solution, valid for low Mach numbers (M ≤ 0 .4), was obtained for the above-mentioned equation by means of a technique developed by Pantuso Sudano. From the solution found, we traced graphs for the quantities which described the equilibrium state of the plasma, namely: mass density, pressure, temperature, electric current density and toroidal magnetic field. Finally we compare this analitical model with others works which utilized differents analitical models and numerical simulations. We conclude that the solutions obtained are in good agreement with the previos results. In addition, however, our model contains the results of Sudano-Goes with the additional advantage of employing much simple analitical expressions. (author) [pt

Unstable universal drift eigenmodes in toroidal plasmas

International Nuclear Information System (INIS)

Cheng, C.Z.; Chen, L.

1979-08-01

The eigenmode equation describing ballooning collisionless drift instabilities is analyzed both analytically and numerically. A new branch of eigenmodes, which corresponds to quasi-bound states due to the finite toroidicity, is shown to be destabilized by electron Landau damping for typical Tokamak parameters. This branch cannot be understood by the strong coupling approximation. However, the slab-like (Pearlstein-Berk type) branch is found to remain stable and experience enhanced shear damping due to finite toroidicity

Review and perspectives of electrostatic turbulence and transport studies in the basic plasma physics device TORPEX

Science.gov (United States)

Avino, Fabio; Bovet, Alexandre; Fasoli, Ambrogio; Furno, Ivo; Gustafson, Kyle; Loizu, Joaquim; Ricci, Paolo; Theiler, Christian

2012-10-01

TORPEX is a basic plasma physics toroidal device located at the CRPP-EPFL in Lausanne. In TORPEX, a vertical magnetic field superposed on a toroidal field creates helicoidal field lines with both ends terminating on the torus vessel. We review recent advances in the understanding and control of electrostatic interchange turbulence, associated structures and their effect on suprathermal ions. These advances are obtained using high-resolution diagnostics of plasma parameters and wave fields throughout the whole device cross-section, fluid models and numerical simulations. Furthermore, we discuss future developments including the possibility of generating closed field line configurations with rotational transform using an internal toroidal wire carrying a current. This system will also allow the study of innovative fusion-relevant configurations, such as the snowflake divertor.

Superconducting magnets for toroidal fusion reactors

International Nuclear Information System (INIS)

Haubenreich, P.N.

1980-01-01

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

Mirror theory applied to toroidal systems

International Nuclear Information System (INIS)

Cohen, R.H.

1987-01-01

Central features of a mirror plasma are strong departures from Maxwellian distribution functions, ambipolar potentials and densities which vary along a field line, and losses, and the mirror field itself. To examine these features, mirror theorists have developed analytical and numerical techniques to solve the Fokker-Planck equation, evaluate the potentials consistent with the resulting distribution functions, and assess the microstability of these distributions. Various combinations of mirror-plasma fetures are present and important in toroidal plasmas as well, particularly in the edge region and in plasmas with strong r.f. heating. In this paper we survey problems in toroidal plasmas where mirror theory and computational techniques are applicable, and discuss in more detail three specific examples: calculation of the toroidal generalization of the Spitzer-Haerm distribution function (from which trapped-particle effects on current drive can be calculated), evaluation of the nonuniform potential and density set up by pulsed electron-cyclotron heating, and calculation of steady-state distribution functions in the presence of strong r.f. heating and collisions. 37 refs., 3 figs

Mirror theory applied to toroidal systems

International Nuclear Information System (INIS)

Cohen, R.H.

1987-01-01

Central features of a mirror plasma are strong departures from Maxwellian distribution functions, ambipolar potentials and densities which vary along a field line, end losses, and the mirror field itself. To examine these features, mirror theorists have developed analytical and numerical techniques to solve the Fokker-Planck equation, evaluate the potentials consistent with the resulting distribution functions, and assess the microstability of these distributions. Various combinations of mirror-plasma features are present and important in toroidal plasmas as well, particularly in the edge region and in plasmas with strong rf heating. In this paper we survey problems in toroidal plasmas where mirror theory and computational techniques are applicable, and discuss in more detail three specific examples: calculation of the toroidal generalization of the Spitzer-Haerm distribution function (from which trapped-particle effects on current drive can be calculated), evaluation of the nonuniform potential and density set up by pulsed electron-cyclotron heating, and calculation of steady-state distribution functions in the presence of strong rf heating and collisions. 37 refs

Divertors for Helical Devices: Concepts, Plans, Results, and Problems

International Nuclear Information System (INIS)

Koenig, R.; Grigull, P.; McCormick, K.

2004-01-01

With Large Helical Device (LHD) and Wendelstein 7-X (W7-X), the development of helical devices is now taking a large step forward on the path to a steady-state fusion reactor. Important issues that need to be settled in these machines are particle flux and heat control and the impact of divertors on plasma performance in future continuously burning fusion plasmas. The divertor concepts that will initially be explored in these large machines were prepared in smaller-scale devices like Heliotron E, Compact Helical System (CHS), and Wendelstein 7-AS (W7-AS). While advanced divertor scenarios relevant for W7-X were already studied in W7-AS, other smaller-scale experiments like Heliotron-J, CHS, and National Compact Stellarator Experiment will be used for the further development of divertor concepts. The two divertor configurations that are being investigated are the helical and the island divertor, as well as the local island divertor, which was successfully demonstrated on CHS and just went into operation on LHD. At present, on its route to a fully closed helical divertor, LHD operates in an open helical divertor configuration. W7-X will be equipped right from the start with an actively cooled discrete island divertor that will allow quasi-continuous operation. The divertor design is very similar to the one explored on W7-AS. For sufficiently large island sizes and not too long field line connection lengths, this divertor gives access to a partially detached quasi-steady-state operating scenario in a newly found high-density H-mode operating regime, which benefits from high energy and low impurity confinement times, with edge radiation levels of up to 90% and sufficient neutral compression in the subdivertor region (>10) for active pumping. The basic physics of the different divertor concepts and associated implementation problems, like asymmetries due to drifts, accessibility of essential operating scenarios, toroidal asymmetries due to symmetry breaking error fields

Microinstability Studies for the Large Helical Device

International Nuclear Information System (INIS)

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

2002-01-01

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

'Crescent'-shaped tokamak for compact ignition

International Nuclear Information System (INIS)

Yamazaki, K.; Reiersen, W.T.

1985-12-01

A compact high-beta tokamak configuration with ''crescent''-shaped (or ''boomerang''-shaped) cross-section is proposed as a next-generation ignition machine. This configuration with a small indentation but a large triangularity is more compact than the normal dee-shaped design because of its high-beta characteristics in the first-second transition regime of stability. This may also be a more reliable next-generation compact device than the bean-shaped design with large indentation and small triangularity, because this design dose not rely on the second stability and is easily extendable from the present dee-shaped design. (author)

'Crescent'-shaped tokamak for compact ignition

International Nuclear Information System (INIS)

Yamazaki, K.; Reiersen, W.T.

1986-01-01

A compact high-beta tokamak configuration with ''crescent''-shaped (or ''boomerang''-shaped) cross section is proposed as a next-generation ignition machine. This configuration with a small indentation but a large triangularity is more compact than the normal dee-shaped design because of its high-beta characteristics in the first-second transition regime of stability. This may also be a more reliable next-generation compact device than the bean-shaped design with large indentation and small triangularity, because this design does not rely on the second stability and is easily extendable from the present dee-shaped design. (author)

Theory for neoclassical toroidal plasma viscosity in tokamaks

International Nuclear Information System (INIS)

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

2012-01-01

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

Controlled Compact High Voltage Power Lines

Directory of Open Access Journals (Sweden)

Postolati V.

2016-04-01

Full Text Available Nowadays modern overhead transmission lines (OHL constructions having several significant differences from conventional ones are being used in power grids more and more widely. Implementation of compact overhead lines equipped with FACTS devices, including phase angle regulator settings (compact controlled OHL, appears to be one of the most effective ways of power grid development. Compact controlled AC HV OHL represent a new generation of power transmission lines embodying recent advanced achievements in design solutions, including towers and insulation, together with interconnection schemes and control systems. Results of comprehensive research and development in relation to 110–500kV compact controlled power transmission lines together with theoretical basis, substantiation, and methodological approaches to their practical application are presented in the present paper.

Closed Loop Control Compact Exercise Device for Use on MPCV

Science.gov (United States)

Sheehan, Chris; Funk, Justin; Funk, Nathan; Kutnick, Gilead; Humphreys, Brad; Bruinsma, Douwe; Perusek, Gail

2016-01-01

Long duration space travel to Mars or to an asteroid will expose astronauts to extended periods of reduced gravity. To combat spaceflight physiological deconditioning, astronauts will use resistive and aerobic exercise regimens for the duration of the space flight to minimize the loss of bone density, muscle mass and aerobic capacity that occurs during exposure to a reduced gravity environment. Unlike the International Space Station (ISS), the mass and volume available for an exercise device in the next generation of spacecraft is limited. Therefore, compact exercise device prototypes are being developed for human in the loop evaluations. The NASA Human Research Program (HRP) is managing Advanced Exercise Concepts (AEC) requirements development and candidate technology maturation for all exploration mission profiles from Multi-Purpose Crew Vehicle (MPCV) exploration missions (e.g., EM-2, up to 21 day) to Mars Transit (up to 1000 day) missions. Numerous technologies have been considered and evaluated against HRP-approved functional requirements and include flywheel, pneumatic and closed-loop microprocessor-controlled motor driven power plants. Motor driven technologies offer excellent torque density and load accuracy characteristics as well as the ability to create custom mechanical impedance (the dynamic relationship between force and velocity) and custom load versus position exercise algorithms. Further, closed-loop motor-driven technologies offer the ability to monitor exercise dose parameters and adapt to the needs of the crewmember for real time optimization of exercise prescriptions. A simple proportional-integral-derivative (PID) controller is demonstrated in a prototype motor driven exercise device with comparison to resistive static and dynamic load set points and aerobic work rate targets. The resistive load term in the algorithm includes a constant force component (Fcmg) as well as inertial component (Fima) and a discussion of system tuning is presented

Assembly of the PLT device

International Nuclear Information System (INIS)

Marino, R.

1975-11-01

The assembly of the PLT device began in June 1974 with a preassembly of the mechanical structure at a remote site. The preassembly sequence incorporated final fabrication procedures with an initial staging operation. This successful staging/fabrication procedure proved to be an invaluable asset when the final assembly was started in August 1974. The assembly continued with the initial reassembly of the previously tested structural components at the final machine site. Construction was interrupted at several points to allow for toroidal field coil, vacuum vessel, and poloidal coil installation. Two phases of toroidal field coil power tests were included in the assembly sequence prior to, and just after the vacuum vessel insertion

Influence of toroidal rotation on resistive tearing modes in tokamaks

International Nuclear Information System (INIS)

Wang, S.; Ma, Z. W.

2015-01-01

Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ R /τ V  ≫ 1, where τ R and τ V represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ R /τ V  ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large

Effects of toroidicity on resistive tearing modes

International Nuclear Information System (INIS)

Izzo, R.; Monticello, D.A.; Manickam, J.; Strauss, H.R.; Grimm, R.; McGuire, K.

1983-03-01

A reduced set of resistive MHD equations is solved numerically in three dimensions to study the stability of tokamak plasmas. Toroidal effects are included self-consistently to leading and next order in inverse aspect ratio, epsilon. The equations satisfy an energy integral. In addition, the momentum equation yields the Grad-Shafranov equation correct to all orders in epsilon. Low beta plasma are studied using several different q-profiles. In all cases, the linear growth rates are reduced by finite toroidicity. Excellent agreement with resistive PEST is obtianed. In some cases, toroidal effects lead to complete stabilization of the mode. Nonlinear results show smaller saturated island widths for finite aspect ratio compared to the cylindrical limit. If the current channel is wide enough so as to produce steep gradients towards the outside of the plasma, both the finite aspect ratio cases and cylindrical cases disrupt

Kinetic energy principle and neoclassical toroidal torque in tokamaks

International Nuclear Information System (INIS)

Park, Jong-Kyu

2011-01-01

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

Toroidal field effects on the stability of Heliotron E

International Nuclear Information System (INIS)

Carreras, B.A.; Garcia, L.; Lynch, V.E.

1986-02-01

The addition of a small toroidal field to the Heliotron E configuration improves the stability of the n = 1 mode and increases the value of the stability beta critical. Total stabilization of this mode can be achieved with added toroidal fields between 5 and 15% of the total field. In this situation, the plasma can have direct access to the second stability regime. For the Heliotron E configuration, the self-stabilization effect is due to the shear, not to the magnetic well. The toroidal field threshold value for stability depends strongly on the pressure profile and the plasma radius. 21 refs., 15 figs

Toroidal drift magnetic pumping

International Nuclear Information System (INIS)

Canobbio, E.

1977-01-01

A set of azimuthal coils which carry properly dephased rf-currents in the KHz frequency range can be used to heat toroidal plasmas by perpendicular Landau damping of subsonic Alfven waves. The heating mechanism and the rf-field structure are discussed in some detail

Classification of symmetric toroidal orbifolds

Energy Technology Data Exchange (ETDEWEB)

Fischer, Maximilian; Ratz, Michael; Torrado, Jesus [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-09-15

We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N{>=}1 supersymmetry in 4D for the heterotic string. Our strategy is based on a classification of crystallographic space groups in six dimensions. We find in total 520 inequivalent toroidal orbifolds, 162 of them with Abelian point groups such as Z{sub 3}, Z{sub 4}, Z{sub 6}-I etc. and 358 with non-Abelian point groups such as S{sub 3}, D{sub 4}, A{sub 4} etc. We also briefly explore the properties of some orbifolds with Abelian point groups and N=1, i.e. specify the Hodge numbers and comment on the possible mechanisms (local or non-local) of gauge symmetry breaking.

Compact fuel storage rack for fuel pools

International Nuclear Information System (INIS)

Parras, F.; Louvat, J.P.

1986-01-01

ETS LEMER and FRAMATOME propose a new compact storage rack. This rack permits a considerable increase of the storage capacity of cooling pools. A short description of the structure and the components is presented, to propose racks that are: . Inalterable, . Compact, . Insensitive to earthquakes. Installation in pools already in operation is simplified by their light structure and the bearing device [fr

Elmo bumpy square plasma confinement device

Science.gov (United States)

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.

Neoclassical poloidal and toroidal rotation in tokamaks

International Nuclear Information System (INIS)

Kim, Y.B.; Diamond, P.H.; Groebner, R.J.

1991-01-01

Explicit expressions for the neoclassical poloidal and toroidal rotation speeds of primary ion and impurity species are derived via the Hirshman and Sigmar moment approach. The rotation speeds of the primary ion can be significantly different from those of impurities in various interesting cases. The rapid increase of impurity poloidal rotation in the edge region of H-mode discharges in tokamaks can be explained by a rapid steepening of the primary ion pressure gradient. Depending on ion collisionality, the poloidal rotation speed of the primary ions at the edge can be quite small and the flow direction may be opposite to that of the impurities. This may cast considerable doubts on current L to H bifurcation models based on primary ion poloidal rotation only. Also, the difference between the toroidal rotation velocities of primary ions and impurities is not negligible in various cases. In Ohmic plasmas, the parallel electric field induces a large impurity toroidal rotation close to the magnetic axis, which seems to agree with experimental observations. In the ion banana and plateau regime, there can be non-negligible disparities between primary ion and impurity toroidal rotation velocities due to the ion density and temperature gradients. Detailed analytic expressions for the primary ion and impurity rotation speeds are presented, and the methodology for generalization to the case of several impurity species is also presented for future numerical evaluation

Toroidal inhomogeneity of the vertical field in a tokamak apparatus

International Nuclear Information System (INIS)

Sometani, Taro; Takashima, Hidekazu

1977-01-01

An experiment with a model device has been made on the toroidal inhomogeneity of the vertical field in a Tokamak with an iron core. The D.C. vertical field is increased near the yokes of the iron core, while the gross plasma image field (consisting of the components due to the plasma current, the primary current, and its image) is reduced there. These two vertical fields, when superposed, exert force on the plasma as a less inhomogeneous external vertical field. The vertical field can be homogenized satisfactorily by using a compensation winding wound at a proper position on the iron core even if the shielding plates, which are mounted on some Tokamaks, are dispensed with. (auth.)

Suppression of tilting instability of a compact torus by energetic particle beams

International Nuclear Information System (INIS)

Nomura, Yasuyuki.

1984-11-01

It is shown that the tilting instability of a compact torus can be suppressed by toroidally circulating energetic particle beams. The stabilizing mechanism is based on the properties of the forced oscillation in the motion of beam particles in a plasma ring. The required beam current for the stabilization is estimated to be sufficiently small compared to the plasma current in the case that the angular velocity of beam particles is close to the betatron frequency. This stabilizing method is applied to a field reversed configuration. Effects of the plasma surface current and beam divergences are also examined. (author)

Estafette of drift resonances, stochasticity and control of particle motion in a toroidal magnetic trap

International Nuclear Information System (INIS)

Shishkin, Alexander A.

2001-02-01

A new method of particle motion control in toroidal magnetic traps with rotational transform using the estafette of drift resonances and stochasticity of particle trajectories is proposed. The use of the word estafette' here means that the particle passes through a set of resonances in consecutive order from one to another during its motion. The overlapping of adjacent resonances can be moved radially from the center to the edge of the plasma by switching on the corresponding perturbations in accordance with a particular rule in time. In this way particles (e.g. cold alpha-particle) can be removed from the center of the confinement volume to the plasma periphery. For the analytical treatment of the stochastic behaviour of particle motion the stochastic diffusion coefficients D r, r, D r,θ , D θ,θ are introduced. The new approach is demonstrated by numerical computations of the test helium particle trajectories in the toroidal trap Large Helical Device. (author)

Reversed field pinch diagnostics

International Nuclear Information System (INIS)

Weber, P.G.

1986-01-01

The Reversed Field Pinch (RFP) is a toroidal, axisymmetric magnetic confinement configuration characterized by a magnetic field configuration in which the toroidal magnetic field is of similar strength to the poloidal field, and is reversed at the edge compared to the center. The RFP routinely operates at high beta, and is a strong candidate for a compact fusion device. Relevant attributes of the configuration will be presented, together with an overview of present and planned experiments and their diagnostics. RFP diagnostics are in many ways similar to those of other magnetic confinement devices (such as tokamaks); these lectures will point out pertinent differences, and will present some diagnostics which provide special insights into unique attributes of the RFP

HTMR: an experimental tokamak reactor with hybrid copper/superconductor toroidal field magnet

International Nuclear Information System (INIS)

Avanzini, P.G.; Raia, G.; Rosatelli, F.; Zampaglione, V.

1985-01-01

The feasibility of a hybrid configuration superconducting coils/copper coils for a next generation tokamak TF magnet has been investigated. On the basis of this hybrid solution, the conceptual design has been developed for a medium-high toroidal field tokamak reactor (HTMR). The results of this study show the possibility of designing a tokamak reactor with reduced size in comparison with other INTOR like devices, still gaining some margins in front of the uncertainties in the scaling laws for plasma physics parameters and retaining the presence of a blanket with a tritium breeding ratio of about 1

Heat characteristic analysis of a conduction cooling toroidal-type SMES magnet

International Nuclear Information System (INIS)

Kim, K.M.; Kim, A.R.; Kim, J.G.; Kim, D.W.; Park, M.; Yu, I.K.; Eom, B.Y.; Sim, K.; Kim, S.H.; Shon, M.H.; Kim, H.J.; Bae, H.J.; Seong, K.C.

2010-01-01

This paper analyzed the heat characteristics of a conduction cooling toroidal-type SMES magnet. The authors designed and manufactured a conduction cooling toroidal-type SMES magnet which consists of 30 double pancake coils. One (a single pancake coil) of a double pancake coil is arranged at an angle of 6 o from each other. The shape of the toroidal-type SMES magnet was designed by a 3D CAD program. The heat invasion was investigated under no-load condition and the thermal characteristic of the toroidal-type SMES magnet was analyzed using the Finite Elements Method program. Both the analyzed and the experiment results are compared and discussed in detail.

Confinement time exceeding one second for a toroidal electron plasma.

Science.gov (United States)

Marler, J P; Stoneking, M R

2008-04-18

Nearly steady-state electron plasmas are trapped in a toroidal magnetic field for the first time. We report the first results from a new toroidal electron plasma experiment, the Lawrence Non-neutral Torus II, in which electron densities on the order of 10(7) cm(-3) are trapped in a 270-degree toroidal arc (670 G toroidal magnetic field) by application of trapping potentials to segments of a conducting shell. The total charge inferred from measurements of the frequency of the m=1 diocotron mode is observed to decay on a 3 s time scale, a time scale that approaches the predicted limit due to magnetic pumping transport. Three seconds represents approximately equal to 10(5) periods of the lowest frequency plasma mode, indicating that nearly steady-state conditions are achieved.

Influence of toroidal rotation on resistive tearing modes in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Wang, S.; Ma, Z. W., E-mail: zwma@zju.edu.cn [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China)

2015-12-15

Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ{sub R}/τ{sub V} ≫ 1, where τ{sub R} and τ{sub V} represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ{sub R}/τ{sub V} ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large.

Effects of enhanced elongation and paramagnetism on the parameter space of the ignition spherical torus

International Nuclear Information System (INIS)

Strickler, D.J.; Peng, Y-K.M.; Borowski, S.K.; Selcow, E.C.; Miller, J.B.

1985-01-01

The Ignition Spherical Torus (IST) is a small aspect ratio device retaining only indispensable components along the major axis of a tokamak plasma, such as a cooled, normal conductor producing a toroidal magnetic field. The IST is expected to be a cost-effective approach to ignition by taking advantage of low field, large natural plasma elongation, high plasma current, high beta, and tokamak confinement. These result in compact, high-performance devices with relatively simple magnetic systems as compared with ignition tokamaks of larger aspect ratio. The plasma enhancement of the toroidal field on axis, or plasma paramagnetism, is significant in the IST. The use of this plasma-enhanced field in conventional tokamak beta and density limits leads to increased plasma pressure and performance and therefore smaller device size for a given ignition margin

Effects of 3D magnetic perturbations on toroidal plasmas

International Nuclear Information System (INIS)

Callen, J.D.

2011-01-01

Small three-dimensional (3D) magnetic field perturbations have many interesting and possibly useful effects on tokamak and quasi-symmetric stellarator plasmas. Plasma transport equations that include these effects, most notably on diamagnetic-level toroidal plasma flows, have recently been developed. The 3D field perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (say 1-5) resonant (with field line pitch, q = m/n) and non-resonant fields, medium n (∼20, due to toroidal field ripple) and high n (due to microturbulence). Low n non-resonant fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal rotation throughout the plasma towards an offset rotation in the counter-current direction. Recent tokamak experiments have generally confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n toroidal field ripple produces similar effects plus possible ripple-trapping NTV effects and ion direct losses in the edge. A low n (e.g. n = 1) resonant field is mostly shielded by the toroidally rotating plasma at and inside the resonant (rational) surface. If it is large enough it can stop plasma rotation at the rational surface, facilitate magnetic reconnection there and lead to a growing stationary magnetic island (locked mode), which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components. In the plasma their lowest n (e.g. n = 1) externally resonant components can be amplified by kink-type plasma responses, particularly at high β. Low n plasma instabilities (e.g. resistive wall modes, neoclassical tearing modes) cause additional 3D magnetic perturbations in tokamak plasmas. Tearing modes in their nonlinear (Rutherford) regime bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can, if not shielded by plasma rotation effects, cause local magnetic

Pareto optimal design of sectored toroidal superconducting magnet for SMES

Science.gov (United States)

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.

Investigation on the effect of temperature excursion on the helium defects of tungsten surface by using compact plasma device

International Nuclear Information System (INIS)

Takamura, S.; Miyamoto, T.; Tomida, Y.; Minagawa, T.; Ohno, N.

2011-01-01

The effects of temperature excursion on the helium defects of tungsten surface have been investigated by using compact plasma device AIT-PID (Aichi Institute of Technology - Plasma Irradiation Device). An initial stage of bubble formation has been identified with an order of smaller (sub-micron) bubbles and holes than those in the past in which the micron size is the standard magnitude. The radiation cooling has been detected when a blacking of tungsten surface coming from nanostructure formation is proceeding due to an increase in the emissivity. The temperature increase to the domain (∼1600 K) in bubble/hole formation from that in nanostructure formation has been found to bring a constriction in diameter and a reduction in length of fiber-form nanostructure.

Born-Infeld magnetars: larger than classical toroidal magnetic fields and implications for gravitational-wave astronomy

Science.gov (United States)

Pereira, Jonas P.; Coelho, Jaziel G.; de Lima, Rafael C. R.

2018-05-01

Magnetars are neutron stars presenting bursts and outbursts of X- and soft-gamma rays that can be understood with the presence of very large magnetic fields. In this setting, nonlinear electrodynamics should be taken into account for a more accurate description of such compact systems. We study that in the context of ideal magnetohydrodynamics and make a realization of our analysis to the case of the well known Born-Infeld (BI) electromagnetism in order to come up with some of its astrophysical consequences. We focus here on toroidal magnetic fields as motivated by already known magnetars with low dipolar magnetic fields and their expected relevance in highly magnetized stars. We show that BI electrodynamics leads to larger toroidal magnetic fields when compared to Maxwell's electrodynamics. Hence, one should expect higher production of gravitational waves (GWs) and even more energetic giant flares from nonlinear stars. Given current constraints on BI's scale field, giant flare energetics and magnetic fields in magnetars, we also find that the maximum magnitude of magnetar ellipticities should be 10^{-6}-10^{-5}. Besides, BI electrodynamics may lead to a maximum increase of order 10-20% of the GW energy radiated from a magnetar when compared to Maxwell's, while much larger percentages may arise for other physically motivated scenarios. Thus, nonlinear theories of the electromagnetism might also be probed in the near future with the improvement of GW detectors.

Guiding Center Equations in Toroidal Equilibria

International Nuclear Information System (INIS)

White, Roscoe; Zakharov, Leonid

2002-01-01

Guiding center equations for particle motion in a general toroidal magnetic equilibrium configuration are derived using magnetic coordinates. Previous derivations made use of Boozer coordinates, in which the poloidal and toroidal angle variables are chosen so that the Jacobian is inversely proportional to the square of the magnetic field. It is shown that the equations for guiding center motion in any equilibrium possessing nested flux surfaces have exactly the same simple form as those derived in this special case. This allows the use of more spatially uniform coordinates instead of the Boozer coordinates, greatly increasing the accuracy of calculations in large beta and strongly shaped equilibria

Toroidal Precession as a Geometric Phase

Energy Technology Data Exchange (ETDEWEB)

J.W. Burby and H. Qin

2012-09-26

Toroidal precession is commonly understood as the orbit-averaged toroidal drift of guiding centers in axisymmetric and quasisymmetric configurations. We give a new, more natural description of precession as a geometric phase effect. In particular, we show that the precession angle arises as the holonomy of a guiding center's poloidal trajectory relative to a principal connection. The fact that this description is physically appropriate is borne out with new, manifestly coordinate-independent expressions for the precession angle that apply to all types of orbits in tokamaks and quasisymmetric stellarators alike. We then describe how these expressions may be fruitfully employed in numerical calculations of precession.

Hollow nanotubular toroidal polymer microrings.

Science.gov (United States)

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.

Prospects for toroidal fusion reactors

International Nuclear Information System (INIS)

Sheffield, J.; Galambos, J.D.

1994-01-01

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

Mobile glasses-free 3D using compact waveguide hologram

Science.gov (United States)

Pyun, K.; Choi, C.; Morozov, A.; Putilin, A.; Bovsunovskiy, I.; Kim, S.; Ahn, J.; Lee, H.-S.; Lee, S.

2013-02-01

The exploding mobile communication devices make 3D data available anywhere anytime. However, to record and reconstruct 3D, the huge number of optical components is often required, which makes overall device size bulky and image quality degraded due to the error-prone tuning. In addition, if additional glass is required, then user experience of 3D is exhausting and unpleasant. Holography is the ultimate 3D that users experience natural 3D in every direction. For mobile glasses-free 3D experience, it is critical to make holography device that can be as compact and integrated as possible. For reliable and economical mass production, integrated optics is needed as integrated circuits in semiconductor industry. Thus, we propose mobile glasses-free 3D using compact waveguide hologram in terms of overall device sizes, quantity of elements and combined functionality of each element. The main advantages of proposed solution are as follows: First, this solution utilizes various integral optical elements, where each of them is a united not adjustable optical element, replacing separate and adjustable optical elements with various forms and configurations. Second, geometrical form of integral elements provides small sizes of whole device. Third, geometrical form of integral elements allows creating flat device. And finally, absence of adjustable elements provide rigidly of whole device. The usage of integrated optical means based on waveguide holographic elements allows creating a new type of compact and high functional devices for mobile glasses-free 3D applications such as mobile medical 3D data visualization.

Mobile glasses-free 3D using compact waveguide hologram

International Nuclear Information System (INIS)

Pyun, K; Choi, C; Kim, S; Ahn, J; Lee, H-S; Lee, S; Morozov, A; Bovsunovskiy, I; Putilin, A

2013-01-01

The exploding mobile communication devices make 3D data available anywhere anytime. However, to record and reconstruct 3D, the huge number of optical components is often required, which makes overall device size bulky and image quality degraded due to the error-prone tuning. In addition, if additional glass is required, then user experience of 3D is exhausting and unpleasant. Holography is the ultimate 3D that users experience natural 3D in every direction. For mobile glasses-free 3D experience, it is critical to make holography device that can be as compact and integrated as possible. For reliable and economical mass production, integrated optics is needed as integrated circuits in semiconductor industry. Thus, we propose mobile glasses-free 3D using compact waveguide hologram in terms of overall device sizes, quantity of elements and combined functionality of each element. The main advantages of proposed solution are as follows: First, this solution utilizes various integral optical elements, where each of them is a united not adjustable optical element, replacing separate and adjustable optical elements with various forms and configurations. Second, geometrical form of integral elements provides small sizes of whole device. Third, geometrical form of integral elements allows creating flat device. And finally, absence of adjustable elements provide rigidly of whole device. The usage of integrated optical means based on waveguide holographic elements allows creating a new type of compact and high functional devices for mobile glasses-free 3D applications such as mobile medical 3D data visualization.

Rapid Detection of Salmonella enterica in Food Using a Compact Disc-Shaped Device

Directory of Open Access Journals (Sweden)

Shunsuke Furutani

2016-01-01

Full Text Available Rapid detection of food-borne pathogens is essential to public health and the food industry. Although the conventional culture method is highly sensitive, it takes at least a few days to detect food-borne pathogens. Even though polymerase chain reaction (PCR can detect food-borne pathogens in a few hours, it is more expensive and unsatisfactorily sensitive relative to the culture method. We have developed a method to rapidly detect Salmonella enterica by using a compact disc (CD-shaped device that can reduce reagent consumption in conventional PCR. The detection method, which combines culture and PCR, is more rapid than the conventional culture method and is more sensitive and cheaper than PCR. In this study, we also examined a sample preparation method that involved collecting bacterial cells from food. The bacteria collected from chicken meat spiked with S. enterica were mixed with PCR reagents, and PCR was performed on the device. At a low concentration of S. enterica, the collected S. enterica was cultured before PCR for sensitive detection. After cultivation for 4 h, S. enterica at 1.7 × 104 colony-forming units (CFUs·g−1 was detected within 8 h, which included the time needed for sample preparation and detection. Furthermore, the detection of 30 CFUs·g−1 of S. enterica was possible within 12 h including 8 h for cultivation.

Turbulent transport of toroidal angular momentum in low flow gyrokinetics

International Nuclear Information System (INIS)

Parra, Felix I; Catto, Peter J

2010-01-01

We derive a self-consistent equation for the turbulent transport of toroidal angular momentum in tokamaks in the low flow ordering that only requires solving gyrokinetic Fokker-Planck and quasineutrality equations correct to second order in an expansion on the gyroradius over scale length. We also show that according to our orderings the long wavelength toroidal rotation and the long wavelength radial electric field satisfy the neoclassical relation that gives the toroidal rotation as a function of the radial electric field and the radial gradients of pressure and temperature. Thus, the radial electric field can be solved for once the toroidal rotation is calculated from the transport of toroidal angular momentum. Unfortunately, even though this methodology only requires a gyrokinetic model correct to second order in gyroradius over scale length, current gyrokinetic simulations are only valid to first order. To overcome this difficulty, we exploit the smallish ratio B p /B, where B is the total magnetic field and B p is its poloidal component. When B p /B is small, the usual first order gyrokinetic equation provides solutions that are accurate enough to employ for our expression for the transport of toroidal angular momentum. We show that current δf and full f simulations only need small corrections to achieve this accuracy. Full f simulations, however, are still unable to determine the long wavelength, radial electric field from the quasineutrality equation.

Approximations to the non-adiabatic particle response in toroidal geometry

International Nuclear Information System (INIS)

Schep, T.J.; Braams, B.J.

1981-08-01

The non-adiabatic part of the particle response to low-frequency electromagnetic modes with long parallel wavelengths is discussed. Analytic approximations to the kernels of the integrals that relate the amplitudes of the perturbed potentials to the non-adiabatic part of the perturbed density in an axisymmetric toroidal configuration are presented and the results are compared with numerical calculations. It is shown that both in the plane slab and in toroidal geometry the kernel contains a logarithmic singularity. This singularity is associated with particles with vanishing parallel velocity so that, in toroidal geometry, it is related with the behaviour of trapped particles near their turning points. In contrast to the plane slab, in toroidal geometry this logarithmic singularity is mainly real and associated with non-resonant particles. Apart from this logarithmic term, the kernel contains a complex regular part arising from resonant as well as from non-resonant particles. The analytic approximations that will be presented make the dispersion relation of drift-type modes in toroidal geometry amenable to analytic as well as to simpler numerical calculation of the growth rate and of the spatial mode structure

Compact-Toroid Fusion Reactor (CTOR) based on the Field-Reversed Theta Pinch

International Nuclear Information System (INIS)

Hagenson, R.L.; Krakowski, R.A.

1981-01-01

Scoping studies of a translating Compact Torus Reactor (CTOR) have been made on the basis of a dynamic plasma model and an overall systems approach. This CTOR embodiment uses a Field-Reversed Theta Pinch as a plasma source. The field-reversed plasmoid would be formed and compressionally heated to ignition prior to injection into and translation through a linear burn chamber, thereby removing the high-technology plamoid source from the hostile reactor environment. Stabilization of the field-reversed plasmoid would be provided by a passive conducting shell located outside the high-temperature blanket but within the low-field superconducting magnets and associated radition shielding. On the basis of this batch-burn but thermally steady-state approach, a reactor concept emerges with a length below approx. 40 m that generates 300 to 400 MWe of net electrical power with a recirculating power fraction less than 0.15

Development of Toroidal Core Transformers

Energy Technology Data Exchange (ETDEWEB)

de Leon, Francisco [New York Univ. (NYU), Brooklyn, NY (United States). Dept. of Electrical and Computer Engineering

2014-08-01

The original objective of this project was to design, build and test a few prototypes of single-phase dry-type distribution transformers of 25 kVA, 2.4 kV primary to 120 V transformers using cores made of a continuous steel strip shaped like a doughnut (toroid). At different points during the development of the project, the scope was enhanced to include the more practical case of a 25 kVA transformer for a 13.8 kV primary system voltage. Later, the scope was further expanded to design and build a 50 kVA unit to transformer voltage from 7.62 kV to 2x120 V. This is a common transformer used by Con Edison of New York and they are willing to test it in the field. The project officially started in September 2009 and ended in May 2014. The progress was reported periodically to DOE in eighteen quarterly reports. A Continuation Application was submitted to DOE in June 2010. In May 2011 we have requested a non-cost extension of the project. In December 2011, the Statement of Project Objectives (SOPO) was updated to reflect the real conditions and situation of the project as of 2011. A second Continuation Application was made and funding was approved in 2013 by DOE and the end date was extended to May 2014. The technical challenges that were overcome in this project include: the development of the technology to pass the impulse tests, derive a model for the thermal performance, produce a sound mechanical design, and estimate the inrush current. However, the greatest challenge that we faced during the development of the project was the complications of procuring the necessary parts and materials to build the transformers. The actual manufacturing process is relatively fast, but getting all parts together is a very lengthy process. The main products of this project are two prototypes of toroidal distribution transformers of 7.62 kV (to be used in a 13.8 kV system) to 2x120 V secondary (standard utilization voltage); one is rated at 25 kVA and the other at 50 kVA. The 25 k

Analysis of toroidal rotation data for the DIII-D tokamak

International Nuclear Information System (INIS)

John, H.St.; Burrell, K.H.; Groebner, R.; DeBoo, J.; Gohil, P.

1989-01-01

Both poloidal and toroidal rotation are observed during routine neutral beam heating operation of the DIII-D tokamak. Poloidal rotation results and the empirical techniques used to measure toroidal and poloidal rotation speeds are described by Groebner et al. Here we concentrate on the analysis of recent measurements of toroidal rotation made during diverted, H-mode operation of the DIII-D tokamak during co- and counter-neutral beam injection of hydrogen into deuterium plasmas. Similar studies have been previously reported for Doublet III, ASDEX, TFTR, JET and other tokamaks. (author) 13 refs., 4 figs

Dynamics of toroidal spiral strings around five-dimensional black holes

International Nuclear Information System (INIS)

Igata, Takahisa; Ishihara, Hideki

2010-01-01

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.

On the stabilization of toroidal pinches by finite larmor radius effects and toroidal magnetic field

International Nuclear Information System (INIS)

Singh, R.; Weiland, J.

1989-01-01

The radial eigenvalue problem for internal modes in a large aspect ratio toriodal pinch has been solved. A particularly stable regime for a weak but nonzero toroidal magnetic field has been found. (31 refs.)

First End Cap Toroid knocking on the door of SX1

CERN Document Server

Herman Ten Kate

On Tuesday May 29, the first Toroid End Cap for the A-side was transported from its test station next to B180 to the front of the ATLAS surface building SX1. The 240-ton and 12-m high toroid end-cap moved on a special trailer at walking speed, got over various slopes and survived the difficult turn left in front of the entrance at gate B. The toroid had to wait for almost two months to commence its journey to its destination as the cryogenic test down to 80K was already successfully completed by early April. In the next days, the toroid will slide into the SX1 building, turn around its axes by 90 degrees and then gently slide over the first shaft and land on top of the A-side shaft on Wednesday. There, it will descend by 5 m into the shaft using special lifting tooling before it can be connected to the 2x140 tons overhead cranes which will let the toroid go further down to the cavern. End Cap Toroid A on the trailer on its way to the cavern at Point 1. Crossing the main road near entrance A while t...

Tracer gas dispersion in ducts-study of a new compact device using arrays of sonic micro jets

Energy Technology Data Exchange (ETDEWEB)

Silva, A.R. [Instituto Nacional de Engenharia e Tecnologia Industrial (INETI), Lisboa (Portugal); Afonso, C.F. [Faculdade de Engenharia, Universidade do Porto Departmento de Mecanica e Gestao Industrial, Porto (Portugal)

2004-07-01

One of the most feasible ways to measure duct airflows is by tracer gas techniques, especially for complex situations when the duct lengths are short as well as their access, which makes extremely difficult or impossible other methods to be implemented. One problem associated with the implementation of tracer gas technique when the ducts lengths are short is due to the impossibility of achieving complete mixing of the tracer with airflow and its sampling. In this work, the development of a new device for the injection of tracer gas in ducts is discussed as well as a new tracer-sampling device. The developed injection device has a compact tubular shape, with magnetic fixation to be easy to apply in duct walls. An array of sonic micro jets in counter current direction, with the possibility of angular movement according to its main axle ensures a complete mixing of the tracer in very short distances. The tracer-sampling device, with a very effective integration function, feeds the sampling system for analysis. Both devices were tested in a wind tunnel of approximately 21 m total length. The tests distances between injection and integration device considered were: X/Dh = 22; X/Dh = 4; X/Dh 2; and X/Dh = 1. For very short distances of X/Dh = 2 and X/Dh = 1, semi-empirical expressions were needed. A good reproducibility of airflow rate values was obtained. These preliminary tests showed that the practical implementation of tracer gas techniques in HVAC systems for measuring airflow rates with a very short mixing distance is possible with the devices developed. (author)

Overview of recent results from the Advanced Toroidal Facility

International Nuclear Information System (INIS)

Murakami, M.; Anabitarte, E.; Anderson, F.S.B.; Bell, G.L.; Bell, J.D.; Bigelow, T.S.; Carreras, B.A.; Charlton, L.A.; Clark, T.L.; Colchin, R.J.; Crume, E.C. Jr.; Dominguez, N.; Dunlap, J.L.; Dyer, G.R.; England, A.C.; Fisher, P.W.; Gandy, R.F.; Glowienka, J.C.; Goulding, R.H.; Hanson, G.R.; Harris, J.H.; Haste, G.R.; Hidalgo-Vera, C.; Hillis, D.L.; Hiroe, S.; Horton, L.D.; Howe, H.C.; Hutchinson, D.E.; Isler, R.C.; Jernigan, T.C.; Kannan, K.L.; Kaneko, H.; Kwon, M.; Langley, R.A.; Leboeuf, J.N.; Lee, D.K.; Lue, J.W.; Lynch, V.E.; Lyon, J.F.; Ma, C.H.; Menon, M.M.; Mioduszewski, P.K.; Morris, R.N.; Neilson, G.H.; Qualls, A.L.; Rasmussen, D.A.; Ritz, C.P.; Rogers, P.S.; Schwenterly, S.W.; Shaing, K.C.; Shaw, P.L.; Shepard, T.D.; Simpkins, J.E.; Stewart, K.A.; Sudo, S.; Thomas, C.E.; Tolliver, J.S.; Uckan, T.; Wade, M.R.; Wilgen, J.B.; Wing, W.R.; Yamada, H.; Zielinski, J.J.

1990-02-01

An overview of recent experimental results from the Advanced Toroidal Facility (ATF) is presented. Beam-heated plasmas with bar n e of 10 20 m -3 and τ E * of ∼ 20 ms have been achieved. Thermal collapse of the plasmas is mitigated by wall conditioning and particle fueling. Confinement time scales positively with density and magnetic field, offsetting deterioration with power. Results fit the Large Helical Device (LHD) scaling and the drift wave turbulence scaling. Bootstrap currents observed during electron cyclotron heating agree with neoclassical theory in magnitude and parameter dependences. Fast reciprocating Langmuir probe measurements show that edge fluctuations in ATF have many similarities to those in the Texas Experimental Tokamak (TEXT). The location of B instabilities has shifted outward in radius, consistent with the broader pressure profiles. 14 refs., 6 figs

Linear wave propagation in a hot axisymmetric toroidal plasma

International Nuclear Information System (INIS)

Jaun, A.

1995-03-01

Kinetic effects on the propagation of the Alfven wave are studied for the first time in a toroidal plasma relevant for experiments. This requires the resolution of a set of coupled partial differential equations whose coefficients depend locally on the plasma parameters. For this purpose, a numerical wave propagation code called PENN has been developed using either a bilinear or a bicubic Hermite finite element discretization. It solves Maxwell's equations in toroidal geometry, with a dielectric tensor operator that takes into account the linear response of the plasma. Two different models have been implemented and can be used comparatively to describe the same physical case: the first treats the plasma as resistive fluids and gives results which are in good agreement with toroidal fluid codes. The second is a kinetic model and takes into account the finite size of the Larmor radii; it has successfully been tested against a kinetic plasma model in cylindrical geometry. New results have been obtained when studying kinetic effects in toroidal geometry. Two different conversion mechanisms to the kinetic Alfven wave have been described: one occurs at toroidally coupled resonant surfaces and is the kinetic counterpart of the fluid models' resonance absorption. The other has no such correspondence and results directly from the toroidal coupling between the kinetic Alfven wave and the global wavefield. An analysis of a heating scenario suggests that it might be difficult to heat a plasma with Alfven waves up to temperatures that are relevant for a tokamak reactor. Kinetic effects are studied for three types of global Alfven modes (GAE, TAE, BAE) and a new class of kinetic eigenmodes is described which appear inside the fluid gap: it could be related to recent observations in the JET (Joint European Torus) tokamak. (author) 56 figs., 6 tabs., 58 refs

Linear wave propagation in a hot axisymmetric toroidal plasma

Energy Technology Data Exchange (ETDEWEB)

Jaun, A [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

1995-03-01

Kinetic effects on the propagation of the Alfven wave are studied for the first time in a toroidal plasma relevant for experiments. This requires the resolution of a set of coupled partial differential equations whose coefficients depend locally on the plasma parameters. For this purpose, a numerical wave propagation code called PENN has been developed using either a bilinear or a bicubic Hermite finite element discretization. It solves Maxwell`s equations in toroidal geometry, with a dielectric tensor operator that takes into account the linear response of the plasma. Two different models have been implemented and can be used comparatively to describe the same physical case: the first treats the plasma as resistive fluids and gives results which are in good agreement with toroidal fluid codes. The second is a kinetic model and takes into account the finite size of the Larmor radii; it has successfully been tested against a kinetic plasma model in cylindrical geometry. New results have been obtained when studying kinetic effects in toroidal geometry. Two different conversion mechanisms to the kinetic Alfven wave have been described: one occurs at toroidally coupled resonant surfaces and is the kinetic counterpart of the fluid models` resonance absorption. The other has no such correspondence and results directly from the toroidal coupling between the kinetic Alfven wave and the global wavefield. An analysis of a heating scenario suggests that it might be difficult to heat a plasma with Alfven waves up to temperatures that are relevant for a tokamak reactor. Kinetic effects are studied for three types of global Alfven modes (GAE, TAE, BAE) and a new class of kinetic eigenmodes is described which appear inside the fluid gap: it could be related to recent observations in the JET (Joint European Torus) tokamak. (author) 56 figs., 6 tabs., 58 refs.

First ATLAS Barrel Toroid coil casing arrives at CERN

CERN Multimedia

2002-01-01

The first of eight 25-metre long coil casings for the ATLAS experiment's barrel toroid magnet system arrived at CERN on Saturday 2 March by road from Heidelberg. This structure will be part of the largest superconducting toroid magnet ever made.   The first coil casing for the toroidal magnets of Atlas arrives at Building 180. This is the start of an enormous three-dimensional jigsaw puzzle. Each of the eight sets of double pancake coils will be housed inside aluminium coil casings, which in turn will be held inside a stainless steel vacuum vessel. A huge construction, the casing that arrived at CERN measures 25 metres in length and 5 metres in width. It weighs 20 tones. And this is just the beginning of the toroid jigsaw: by early April a batch of four double pancake coils, which altogether weighs 65 tones, will arrive from Ansaldo in Italy. The first vacuum vessel will also be arriving from Felguera in Spain this month. It will take about two years for all these 25 m long structures of casings, coils a...

The comparative analysis of the different mechanisms of toroidal rotation in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Sabot, R [Association Euratom-CEA, Centre d` Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Parail, V [Kurchatov Institute, Moscow (Russian Federation)

1994-07-01

The toroidal plasma rotation appears as one the possible mechanism for suppression of plasma turbulence. Several mechanisms are believed to contribute to the toroidal plasma rotation. The results of numerical simulation of the toroidal rotation on JET are presented, where are taken into consideration the following effects: the neoclassical viscosity due to banana and ripple trapped particles, the anomalous viscosity due to plasma turbulence, the momentum input by NBI (neutron beam injection) and ion momentum loss near the separatrix due to prompt ion losses. The NBI appeared to be the principal source of toroidal plasma rotation. 6 refs., 2 figs.

Safety implications of a graphite oxidation accident in the compact ignition tokamak device

International Nuclear Information System (INIS)

Merrill, B.J.; O'Brien, M.H.

1989-01-01

This paper addresses the possible safety consequences of an air ingress accident for the Compact Ignition Tokamak (CIT) device. An experimental program was undertaken to determine oxidation rates of four nuclear grade graphites in air at temperatures ranging from 800 to 1800 C and flow velocities from 3 to 7 m/s. On the basis of these test results, an analytic model was developed to assess the extent of first wall/divertor protective tile oxidation and the amount of energy released from this oxidation. For CIT, a significant restriction to vacuum vessel air inflow will be provided by the air seals and walls of the surrounding test cells. Under these conditions, the graphite oxidation reaction inside the vacuum vessel will become oxygen starved within minutes of the onset of this event. Since significant oxidation rates were not achieved, the heat release did not elevate structural temperatures to levels of concern with regard to activated material release. 7 refs., 9 figs

Low-frequency fluctuations in a pure toroidal magnetized plasma

Indian Academy of Sciences (India)

A magnetized, low- plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼ 1011 cm-3, ∼ 4 × 1010 cm-3 and ∼ 2 × 1010 cm−3 respectively.

Effects of 3D Magnetic Perturbations on Toroidal Plasmas

International Nuclear Information System (INIS)

Callen, J.D.

2010-01-01

Full text: To lowest order tokamaks are two-dimensional (2D) axisymmetric magnetic systems. But small 3D magnetic perturbations (both externally applied and from plasma instabilities) have many interesting and useful effects on tokamak (and quasi-symmetric stellarator) plasmas. Plasma transport equations that include these effects, especially on diamagnetic-level toroidal plasma rotation, have recently been developed. The 3D magnetic perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (1 to 5) resonant (q = m/n in plasma) and non-resonant fields, medium n (due to toroidal field ripple), and high n (due to microturbulence). This paper concentrates on low and medium n perturbations. Low n non-resonant magnetic fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal plasma rotation throughout the plasma toward an offset flow in the counter-I p direction; recent tokamak experiments have confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n perturbations have similar effects plus possible ripple trapping and resultant edge ion losses. A low n resonant magnetic field induces a toroidal plasma torque in the vicinity of the rational surface; when large enough it can stop plasma rotation there and lead to a locked mode, which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components; in the plasma their lowest n components are amplified by plasma responses, particularly at high beta. Low n plasma instabilities (e.g., NTMs, RWMs) cause additional 3D magnetic perturbations in tokamak plasmas; tearing modes can bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can cause local magnetic stochasticity and influence H-mode edge pedestal transport. These various effects of 3D magnetic perturbations can be used to control the toroidal plasma

Polymer- and salt-induced toroids of hexagonal DNA.

OpenAIRE

Ubbink, J; Odijk, T

1995-01-01

A model is proposed for polymer- and salt-induced toroidal condensates of DNA, based on a recent theory of the undulation enhancement of the electrostatic interaction in the bulk hexagonal phase of semiflexible polyions. In a continuum approximation, the thermodynamic potential of a monomolecular toroid may be split up in bulk, surface, and curvature contributions. With the help of an approximate analytical minimization procedure, the optimal torus dimensions are calculated as a function of t...

Reynolds stress of localized toroidal modes

International Nuclear Information System (INIS)

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

1995-02-01

An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant

Reynolds stress of localized toroidal modes

International Nuclear Information System (INIS)

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

1995-01-01

An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant. (author). 15 refs

Toroidal Dielectric Tensor-Operator for Arbitrary Aspect-Ratio and Wave Frequency an Anisotropic-Resistivity MHD Formulation

International Nuclear Information System (INIS)

Komoshvili, K.; Cuperman, S.

1998-01-01

Motivated by the recently increased interest in small aspect ratio tokamaks, we have derived a 2(1/2)D dielectric tensor-operator which can properly describe the plasma response to r.f. waves, under conditions prevailing in the pre-heated stages of arbitrary aspect ratio, axisymmetric toroidal fusion devices. The derived dielectric tensor elements are based on a two-fluid, weakly collisional plasma description, with the Hall term included. They are characterized by the following features: (i) They are cast in a form evidencing the dielectric (non-operator) and operator contributions - the latter being due to the toroidal structure of the V-operators present in Maxwell's equations, on the background of equilibrium currents and pressure gradients; (ii) They are not subject to any I imitation on the (relative) magnitude of the toroidal effects - no expansion in the inverse aspect ratio parameter is used for their derivation; (iii) They include anisotropic - parallel and perpendicular to the magnetic field - contributions to the plasma resistivity; (iv) They are not Iimited by any restriction on the (relative) value of the wave frequency. The explicit, physically transparent formulation of the dielectric tensor is intended for the numerical solution of the full (E ll ≠ 0) wave equation and subsequently, evaluation of the Alfven wave current drive in small aspect ratio tokamaks

The rotamak - contributions from ANSTO and Flinders University

International Nuclear Information System (INIS)

Jones, I.R.

1998-01-01

Full text: The investigation of plasma/field configurations of the compact torus variety is of current interest in the field of fusion research. Two configurations of this genre are the field reversed configuration (FRC), which does not have an externally applied toroidal magnetic field, and the spherical tokamak (ST) which possesses such a field. Both of these compact torus concepts, as studied outside Australia, suffer from the very serious disadvantage that they are inherently pulsed devices; the toroidal plasma current is not maintained indefinitely. The rotamak is a compact torus configuration having the unique and distinctive feature that the toroidal plasma current is driven in a steady-state, non-inductive fashion by means of the application of a rotating magnetic field. In its basic form, the rotamak is operated as an FRC. However, by means of a simple modification, a steady toroidal magnetic field can be added to the basic rotamak apparatus and the configuration then becomes that of an ST. The rotamak concept was conceived and developed in Australia and the bulk of investigations in this field, both theoretical and experimental, have been undertaken at Flinders University (1979-1998) and AAEC/ANSTO (1982-1988). This talk will cover the history of the project in this country, will dwell on the marvelous interaction which flourished between the two research groups and will finish with the news that the rotamak concept has been enthusiastically embraced by fusion research teams in the United States

Effects of Resonant Helical Field on Toroidal Field Ripple in IR-T1 Tokamak

Science.gov (United States)

Mahdavipour, B.; Salar Elahi, A.; Ghoranneviss, M.

2018-02-01

The toroidal magnetic field which is created by toroidal coils has the ripple in torus space. This magnetic field ripple has an importance in plasma equilibrium and stability studies in tokamak. In this paper, we present the investigation of the interaction between the toroidal magnetic field ripple and resonant helical field (RHF). We have estimated the amplitude of toroidal field ripples without and with RHF (with different q = m/n) ( m = 2, m = 3, m = 4, m = 5, m = 2 & 3, n = 1) using “Comsol Multiphysics” software. The simulations show that RHF has effects on the toroidal ripples.

Plasma flow in toroidal systems with a separatrix

International Nuclear Information System (INIS)

Gribkov, V.M.; Morozov, D.Kh.; Pogutse, O.P.

1984-01-01

A hydrodynamic plasma flow in toroidal systems is considered. Rlasma flow lines for various magnetic configurations are calculated. A particular attention is given to studying plasma flow in configurations with two magnetic a axes and a separatrix. The flow picture i the toroidal case is shown to qualita ity to penetrate through the separatrix - the latter becomes ''perforated''. Th he pictkre of these flows is calculated. The plasma diffusion coefficient with account for the separatrix is calculated and is shown not to turn into the infin nity in the toroidal case as well. The plasma flow is analytically considered in the model with distributed current as well as in the model with current conce entrated at the oroidal system axis. In the first case the existence of ''stagnant'' regions near the magnetic axis is established from which the plasma a does not flow out

Design and characterization of a novel toroidal split-ring resonator

International Nuclear Information System (INIS)

Bobowski, J. S.; Nakahara, Hiroko

2016-01-01

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

Mode structure and continuum damping of high-n toroidal Alfven eigenmodes

International Nuclear Information System (INIS)

Rosenbluth, M.N.; Berk, H.L.; Van Dam, J.W.; Lindberg, D.M.

1992-02-01

An asymptotic theory is described for calculating the mode structure and continuum damping of short wave-length toroidal Alfven eigenmodes (TAE). The formalism somewhat resembles the treatment used for describing low-frequency toroidal modes with singular structure at a rational surface, where an inner solution, which for the TAE mode has toroidal coupling, is matched to an outer toroidally uncoupled solution. A three-term recursion relation among coupled poloidal harmonic amplitudes is obtained, whose solution gives the structure of the global wavefunction and the complex eigenfrequency, including continuum damping. Both analytic and numerical solutions are presented. The magnitude of the damping is essential for determining the thresholds for instability driven by the spatial gradients of energetic particles (e.g., neutral beam-injected ions or fusion-product alpha particles) contained in a tokamak plasma

Developing a compact multiple laser diode combiner with a single fiber stub output for handheld IoT devices

Science.gov (United States)

Lee, Minseok; June, Seunghyeok; Kim, Sehwan

2018-01-01

Many biomedical applications require an efficient combination and localization of multiple discrete light sources ( e.g., fluorescence and absorbance imaging). We present a compact 6 channel combiner that couples the output of independent solid-state light sources into a single 400-μm-diameter fiber stub for handheld Internet of Things (IoT) devices. We demonstrate average coupling efficiencies > 80% for each of the 6 laser diodes installed into the prototype. The design supports the use of continuous wave and intensity-modulated laser diodes. This fiber-stub-type beam combiner could be used to construct custom multi-wavelength sources for tissue oximeters, microscopes and molecular imaging technologies. In order to validate its suitability, we applied the developed fiber-stub-type beam combiner to a multi-wavelength light source for a handheld IoT device and demonstrated its feasibility for smart healthcare through a tumor-mimicking silicon phantom.

Hybrid winding concept for toroids

DEFF Research Database (Denmark)

Schneider, Henrik; Andersen, Thomas; Knott, Arnold

2013-01-01

and placement machinery. This opens up the possibility for both an automated manufacturing process and an automated production process of toroidal magnetics such as power inductors, filtering inductors, air core inductors, transformers etc. Both the proposed hybrid and the common wire wound winding...

Form coefficient of helical toroidal solenoids

International Nuclear Information System (INIS)

Amelin, V.Z.; Kunchenko, V.B.

1982-01-01

For toroidal solenoids with continuous spiral coil, winded according to the laws of equiinclined and simple cylindrical spirals with homogeneous, linearly increasing to the coil periphery and ''Bitter'' distribution of current density, the analytical expressions for the dependence between capacity consumed and generated magnetic field, expressions for coefficients of form similar to Fabry coefficient for cylindrical solenoids are obtained and dependence of the form coefficient and relative volume of solenoid conductor on the number of revolutions of screw line per one circumvention over the large torus radius is also investigated. Analytical expressions of form coefficients and graphical material permit to select the optimum geometry as to capacity consumed both for spiral (including ''force-free'') and conventional toroidal solenoids of magnetic systems in thermonulear installations

1D equation for toroidal momentum transport in a tokamak

International Nuclear Information System (INIS)

Rozhansky, V A; Senichenkov, I Yu

2010-01-01

A 1D equation for toroidal momentum transport is derived for a given set of turbulent transport coefficients. The averaging is performed taking account of the poloidal variation of the toroidal fluxes and is based on the ambipolar condition of the zero net radial current through the flux surface. It is demonstrated that taking account of the Pfirsch-Schlueter fluxes leads to a torque in the toroidal direction which is proportional to the gradient of the ion temperature. This effect is new and has not been discussed before. The boundary condition at the separatrix, which is based on the results of the 2D simulations of the edge plasma, is formulated.

Deformation energy of a toroidal nucleus and plane fragmentation barriers

International Nuclear Information System (INIS)

Fauchard, C.; Royer, G.

1996-01-01

The path leading to pumpkin-like configurations and toroidal shapes is investigated using a one-parameter shape sequence. The deformation energy is determined within the analytical expressions obtained for the various shape-dependent functions and the generalized rotating liquid drop model taking into account the proximity energy and the temperature. With increasing mass and angular momentum, a potential well appears in the toroidal shape path. For the heaviest systems, the pocket is large and locally favourable with respect to the plane fragmentation barriers which might allow the formation of evanescent toroidal systems which would rapidly decay in several fragments to minimize the surface tension. (orig.)

Femtometer toroidal structures in nuclei

International Nuclear Information System (INIS)

Forest, J.L.; Pandharipande, V.R.; Pieper, S.C.; Wiringa, R.B.; Schiavilla, R.; Arriaga, A.

1996-01-01

The two-nucleon density distributions in states with isospin T=0, spin S=1, and projection M S =0 and ±1 are studied in 2 H, 3,4 He, 6,7 Li, and 16 O. The equidensity surfaces for M S =0 distributions are found to be toroidal in shape, while those of M S =±1 have dumbbell shapes at large density. The dumbbell shapes are generated by rotating tori. The toroidal shapes indicate that the tensor correlations have near maximal strength at r 3 He, 4 He, and 6 Li. The toroidal distribution has a maximum-density diameter of ∼1 fm and a half-maximum density thickness of ∼0.9 fm. Many realistic models of nuclear forces predict these values, which are supported by the observed electromagnetic form factors of the deuteron, and also predicted by classical Skyrme effective Lagrangians, related to QCD in the limit of infinite colors. Due to the rather small size of this structure, it could have a revealing relation to certain aspects of QCD. Experiments to probe this structure and its effects in nuclei are suggested. Pair distribution functions in other T,S channels are also discussed; those in T,S=1,1 have anisotropies expected from one-pion-exchange interactions. The tensor correlations in T,S=0,1 states are found to deplete the number of T,S=1,0 pairs in nuclei and cause a reduction in nuclear binding energies via many-body effects. copyright 1996 The American Physical Society

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

International Nuclear Information System (INIS)

Heidbrink, W. W.

2008-01-01

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 ζ is most important. Once a mode is driven unstable, a wide variety of

Development of toroid-type HTS DC reactor series for HVDC system

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwangmin, E-mail: kwangmin81@gmail.com [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Lee, Sangjin [Uiduk University, Gyeongju 780-713 (Korea, Republic of); Oh, Yunsang [Vector Fields Korea Inc., Pohang 790-834 (Korea, Republic of); Park, Minwon; Yu, In-Keun [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of)

2015-11-15

Highlights: • The authors developed the 400 mH, 400 A class toroid-type HTS DC reactor system. • The target temperature, inductance and operating current are under 20 K at magnet, 400 mH and 400 A, respectively. All target performances of the HTS DC reactor were achieved. • The HTS DC reactor was conducted through the interconnection operation with a LCC type HVDC system. • Now, the authors are studying the 400 mH, 1500 A class toroid-type HTS DC reactor for the next phase HTS DC reactor. - Abstract: This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

Development of toroid-type HTS DC reactor series for HVDC system

International Nuclear Information System (INIS)

Kim, Kwangmin; Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho; Lee, Sangjin; Oh, Yunsang; Park, Minwon; Yu, In-Keun

2015-01-01

Highlights: • The authors developed the 400 mH, 400 A class toroid-type HTS DC reactor system. • The target temperature, inductance and operating current are under 20 K at magnet, 400 mH and 400 A, respectively. All target performances of the HTS DC reactor were achieved. • The HTS DC reactor was conducted through the interconnection operation with a LCC type HVDC system. • Now, the authors are studying the 400 mH, 1500 A class toroid-type HTS DC reactor for the next phase HTS DC reactor. - Abstract: This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

Development of toroid-type HTS DC reactor series for HVDC system

Science.gov (United States)

Kim, Kwangmin; Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho; Lee, Sangjin; Oh, Yunsang; Park, Minwon; Yu, In-Keun

2015-11-01

This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

Toroidal plasma reactor with low external magnetic field

International Nuclear Information System (INIS)

Beklemishev, A.D.; Khayrutdinov, R.R.; Petviashvili, V.I.; Tajima, T.; Gordin, V.A.; Tajima, T.

1991-01-01

A toroidal pinch configuration with safety factor q < 0.5 decreasing from the center to periphery without field reversal is proposed. This is capable of containing high pressure plasma with only small toroidal external magnetic field. Sufficient conditions for magnetohydrodynamic stability are fulfilled in this configuration. The stability is studied by constructing the Lyapunov functional and investigating its extrema both analytically and numerically. Comparison of the Lyapunov stability conditions with the conventional linear theory is carried out. Stable configurations are found with average β near 15%, with magnetic field associated mainly with plasma current. The β value calculated with the external magnetic field can be over 100%. Fast charged particles produced by fusion reactions are asymmetrically confined by the poloidal magnetic field (and due to the lack of strong toroidal field). They thus generate a current in the noncentral part of plasma to reinforce the poloidal field. This current drive can sustain the monotonic decrease of q with radius. 20 refs., 9 figs

Structural analysis of the ITER Divertor toroidal rails

Energy Technology Data Exchange (ETDEWEB)

Viganò, F., E-mail: Fabio.Vigano@LTCalcoli.it [L.T. Calcoli SaS, Piazza Prinetti 26/B, 23807 Merate (Italy); Escourbiac, F.; Gicquel, S.; Komarov, V. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul lez Durance (France); Lucca, F. [L.T. Calcoli SaS, Piazza Prinetti 26/B, 23807 Merate (Italy); Merola, M. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul lez Durance (France); Ngnitewe, R. [L.T. Calcoli SaS, Piazza Prinetti 26/B, 23807 Merate (Italy)

2013-10-15

The Divertor is one of the most technically challenging components of the ITER machine, which has the main function of extracting the power conducted in the scrape-off layer while maintaining the plasma purity. There are 54 Divertor cassettes installed in the vacuum vessel (VV). Each cassette body (CB) is fastened on the inner and outer concentric Divertor toroidal rails. The comprehensive assessment (in accordance with the Structural Design Criteria for ITER In-vessel Components: ITER SDC-IC) of the Divertor toroidal rails has been performed during design activity based on performing of thermal and stress analyses at operating conditions of neutron stage of ITER operation. This paper outlines the engineering aspects of the ITER Divertor toroidal rails and focuses on some critical regions of the present design highlighted by the performed structural assessment. The structural assessment has been performed with help of using Finite Element (FE) Abaqus code and based on criteria given by ITER SDC-IC.

Compact MOSFET models for VLSI design

CERN Document Server

Bhattacharyya, A B

2009-01-01

Practicing designers, students, and educators in the semiconductor field face an ever expanding portfolio of MOSFET models. In Compact MOSFET Models for VLSI Design , A.B. Bhattacharyya presents a unified perspective on the topic, allowing the practitioner to view and interpret device phenomena concurrently using different modeling strategies. Readers will learn to link device physics with model parameters, helping to close the gap between device understanding and its use for optimal circuit performance. Bhattacharyya also lays bare the core physical concepts that will drive the future of VLSI.

Efficiency of wave-driven rigid body rotation toroidal confinement

Science.gov (United States)

Rax, J. M.; Gueroult, R.; Fisch, N. J.

2017-03-01

The compensation of vertical drifts in toroidal magnetic fields through a wave-driven poloidal rotation is compared with compensation through the wave driven toroidal current generation to support the classical magnetic rotational transform. The advantages and drawbacks associated with the sustainment of a radial electric field are compared with those associated with the sustainment of a poloidal magnetic field both in terms of energy content and power dissipation. The energy content of a radial electric field is found to be smaller than the energy content of a poloidal magnetic field for a similar set of orbits. The wave driven radial electric field generation efficiency is similarly shown, at least in the limit of large aspect ratio, to be larger than the efficiency of wave-driven toroidal current generation.

ZONAL TOROIDAL HARMONIC EXPANSIONS OF EXTERNAL GRAVITATIONAL FIELDS FOR RING-LIKE OBJECTS

Energy Technology Data Exchange (ETDEWEB)

Fukushima, Toshio, E-mail: Toshio.Fukushima@nao.ac.jp [National Astronomical Observatory, Ohsawa, Mitaka, Tokyo 181-8588 (Japan)

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.

Electron diamagnetism and toroidal coupling of tearing modes

International Nuclear Information System (INIS)

Cowley, S.C.; Hastie, R.J.

1987-10-01

Using a simple model for the layer of the tearing mode, we demonstrate that toroidally coupled tearing modes with two rational surfaces are most unstable when the ω*'s of the electrons at the rational surfaces are equal. The onset of instability may then occur because of the tuning of ω* rather than the passage of Δ'-like quantities through zero. This mechanism for the onset of instability is sharp since the resonance is narrow. The effect of toroidal rotation is also discussed. 7 refs., 2 figs

Dual-function magnetic structure for toroidal plasma devices

International Nuclear Information System (INIS)

Brown, R.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

Spherical torus, compact fusion at low field

International Nuclear Information System (INIS)

Peng, Y.K.M.

1985-02-01

A spherical torus is obtained by retaining only the indispensable components on the inboard side of a tokamak plasma, such as a cooled, normal conductor that carries current to produce a toroidal magnetic field. The resulting device features an exceptionally small aspect ratio (ranging from below 2 to about 1.3), a naturally elongated D-shaped plasma cross section, and ramp-up of the plasma current primarily by noninductive means. As a result of the favorable dependence of the tokamak plasma behavior to decreasing aspect ratio, a spherical torus is projected to have small size, high beta, and modest field. Assuming Mirnov confinement scaling, an ignition spherical torus at a field of 2 T features a major radius of 1.5 m, a minor radius of 1.0 m, a plasma current of 14 MA, comparable toroidal and poloidal field coil currents, an average beta of 24%, and a fusion power of 50 MW. At 2 T, a Q = 1 spherical torus will have a major radius of 0.8 m, a minor radius of 0.5 m, and a fusion power of a few megawatts

Progress in the design of a superconducting toroidal magnet for the ATLAS detector on LHC

International Nuclear Information System (INIS)

Baze, J.M.; Berriaud, C.; Cure, C.

1996-01-01

The toroidal system consists of three air core superconducting toroids. The barrel toroid covers the central region over a length of 26 m with an inner bore of 9.4 m and an outer diameter of 19.5 m. The two end cap toroids are inserted in the barrel at each end over a length of 5.6 m with an inner bore of 1.26 m. Each toroid consists of eight flat coils assembled around the beam axis and carrying 3 MAt each. The present paper describes the barrel toroid. Features of the design which are presented include the electromagnetic design, field and forces calculations, the basic concept of indirectly cooled aluminium conductor and monolithic fully impregnated winding, the description of the alu-alloy mechanical structure, the thermal analysis and the quench protection. Cryogenics principles, cryostat and toroid assembly procedures are summarized. Unsymmetric loadings, fault sensing and stability are discussed, in relation with the requirements of transparency

EMC3-EIRENE modeling of toroidally-localized divertor gas injection experiments on Alcator C-Mod

Energy Technology Data Exchange (ETDEWEB)

Lore, J.D., E-mail: lorejd@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Reinke, M.L. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); LaBombard, B. [Plasma Science and Fusion Center, MIT, Cambridge, MA 02139 (United States); Lipschultz, B. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Churchill, R.M. [Plasma Science and Fusion Center, MIT, Cambridge, MA 02139 (United States); Pitts, R.A. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Feng, Y. [Max Planck Institute for Plasma Physics, Greifswald (Germany)

2015-08-15

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.

Models for large superconducting toroidal magnet systems

International Nuclear Information System (INIS)

Arendt, F.; Brechna, H.; Erb, J.; Komarek, P.; Krauth, H.; Maurer, W.

1976-01-01

Prior to the design of large GJ toroidal magnet systems it is appropriate to procure small scale models, which can simulate their pertinent properties and allow to investigate their relevant phenomena. The important feature of the model is to show under which circumstances the system performance can be extrapolated to large magnets. Based on parameters such as the maximum magnetic field and the current density, the maximum tolerable magneto-mechanical stresses, a simple method of designing model magnets is presented. It is shown how pertinent design parameters are changed when the toroidal dimensions are altered. In addition some conductor cost estimations are given based on reactor power output and wall loading

Current control necessary for toroidal plasma equilibrium

International Nuclear Information System (INIS)

Nagao, S.

1987-01-01

It is shown that a significant amount of dipole current is necessary for the plasma equilibrium of toroidal configurations in general. Through the vector product with the poloidal field, this dipole current force has to balance with the hoop force of plasma pressure itself of the annular shape. The measurement of such a current of dipole type may be interesting for the confirmation of the plasma equilibrium in the toroidal system. Moreover it is certained that there is a new mode of a tokamak operation with such a dipole current component and with smaller vertical field than that based on the classical tokamak theory. (author) [pt

TFTR toroidal field coil design

International Nuclear Information System (INIS)

Smith, G.E.; Punchard, W.F.B.

1977-01-01

The design of the Tokamak Fusion Test Reactor (TFTR) Toroidal Field (TF) magnetic coils is described. The TF coil is a 44-turn, spiral-wound, two-pancake, water-cooled configuration which, at a coil current of 73.3 kiloamperes, produces a 5.2-Tesla field at a major radius of 2.48 meters. The magnetic coils are installed in titanium cases, which transmit the loads generated in the coils to the adjacent supporting structure. The TFTR utilizes 20 of these coils, positioned radially at 18 0 intervals, to provide the required toroidal field. Because it is very highly loaded and subject to tight volume constraints within the machine, the coil presents unique design problems. The TF coil requirements are summarized, the coil configuration is described, and the problems highlighted which have been encountered thus far in the coil design effort, together with the development tests which have been undertaken to verify the design

The Superconducting Toroid for the New International AXion Observatory (IAXO)

CERN Document Server

Shilon, I.; Silva, H.; Wagner, U.; ten Kate, H.H.J.

2013-01-01

IAXO, the new International AXion Observatory, will feature the most ambitious detector for solar axions to date. Axions are hypothetical particles which were postulated to solve one of the puzzles arising in the standard model of particle physics, namely the strong CP (Charge conjugation and Parity) problem. This detector aims at achieving a sensitivity to the coupling between axions and photons of one order of magnitude beyond the limits of the current detector, the CERN Axion Solar Telescope (CAST). The IAXO detector relies on a high-magnetic field distributed over a very large volume to convert solar axions to detectable X-ray photons. Inspired by the ATLAS barrel and end-cap toroids, a large superconducting toroid is being designed. The toroid comprises eight, one meter wide and twenty one meters long racetrack coils. The assembled toroid is sized 5.2 m in diameter and 25 m in length and its mass is about 250 tons. The useful field in the bores is 2.5 T while the peak magnetic field in the windings is 5....

Elastomer seal for a large toroidal vacuum chamber

International Nuclear Information System (INIS)

Skellett, S.; Casey, F.; Blake, H.

1978-07-01

An aluminium toroidal vacuum chamber for use at 10(-6) torr, whose overall diameter is in the region of 5 metres, was built from 4 component parts which resulted in joint lines in the horizontal and vertical planes crossing each other in 4 places. A viton seal was developed which allows a vacuum tight joint to be made without the need for tightly toleranced fitting of the mating faces and also overcomes the difficulty of ensuring a reliable seal at cross-over joints. Ease of maintenance and repair in situ are important factors of the design. An assembly which presented the geometry of the sealing problem was tested and is described here. Various adhesives for bonding viton were examined for the manufacture of the seal. The most suitable adhesive was found to be Loctite S496, chosen for its bond strength and convenience in use. A device for preparing and bonding the viton in situ is described. (author)

Calculation of modification to the toroidal magnetic field of the Tokamak Novillo. Part II; Calculo de modificacion al campo magnetico toroidal del Tokamak nivillo. Parte II

Energy Technology Data Exchange (ETDEWEB)

Melendez L, L.; Chavez A, E.; Colunga S, S.; Valencia A, R.; Lopez C, R.; Gaytan G, E

1992-03-15

In a cylindrical magnetic topology. the confined plasma experiences 'classic' collisional transport phenomena. When bending the cylinder with the purpose of forming a toro, the magnetic field that before was uniform now it has a radial gradient which produces an unbalance in the magnetic pressure that is exercised on the plasma in the transverse section of the toro. This gives place to transport phenomena call 'neo-classicist'. In this work the structure of the toroidal magnetic field produced by toroidal coils of triangular form, to which are added even of coils of compensation with form of half moon is analyzed. With this type of coils it is looked for to minimize the radial gradient of the toroidal magnetic field. The values and characteristics of B (magnetic field) in perpendicular planes to the toro in different angular positions in the toroidal direction, looking for to cover all the cases of importance are exhibited. (Author)

Neoclassical diffusion in toroidal three-cut magnetic field

International Nuclear Information System (INIS)

Nemov, V.V.; Shishkin, A.A.

1975-01-01

Quasi-classical diffusion is investigated in the regime of toroidal drift of 'bananas' in a three cut magnetic field. Unlike previous papers, it is supposed that the inhomogeneity of a helical magnetic field epsilonsub(k) is of the same order or less than that of the toroidal inhomogeneity epsilonsub(t). The case is considered when the efficient frequency of particle collisions exceeds that of the 'banana' precession around the magnetic axis. Expressions for diffusion flows and coefficients are obtained that transform into available ones at epsilonsub(h) > > epsilonsub(t) [ru

ECRH-assisted plasma start-up with toroidally inclined launch: multi-machine comparison and perspectives for ITER

International Nuclear Information System (INIS)

Stober, J.; Hobirk, J.; Lunt, T.; Jackson, G.L.; Hyatt, A.W.; Luce, T.; Ascasibar, E.; Cappa, A.; Bae, Y.-S.; Joung, M.; Bucalossi, J.; Casper, T.; Gribov, Y.; Cho, M.-H.; Jeong, J.-H.; Namkung, W.; Park, S.-I.; Granucci, G.; Hanada, K.; Ide, S.

2011-01-01

Electron cyclotron resonance heating (ECRH)-assisted plasma breakdown is foreseen with full and half magnetic field in ITER. As reported earlier, the corresponding O1- and X2-schemes have been successfully used to assist pre-ionization and breakdown in present-day devices. This contribution reports on common experiments studying the effect of toroidal inclination of the ECR beam, which is ≥20 0 in ITER. All devices could demonstrate successful breakdown assistance for this case also, although in some experiments the necessary power was almost a factor of 2 higher compared with perpendicular launch. Differences between the devices with regard to the required power and vertical field are discussed and analysed. In contrast to most of these experiments, ITER will build up loop voltage prior to the formation of the field null due to the strong shielding by the vessel. Possible consequences of this difference are discussed.

Design study of the compact ERL

International Nuclear Information System (INIS)

Hajima, Ryoichi; Nakamura, Norio; Sakanaka, Shogo; Kobayashi, Yukinori

2008-02-01

Energy-recovery linac (ERL) is a promising device for future X-ray light sources, which can produce coherent X-rays and femto-second X-ray pulses. In Japan, we have organized a collaboration team, consisting of the members of KEK, JAEA, ISSP and other laboratories, toward realization of future ERL light sources, and started R and D efforts to establish accelerator technologies relevant to the ERL light source. In order to demonstrate all the accelerator technologies working together, we have decided to build a small facility, the Compact ERL. This report presents a design study of the Compact ERL, which includes R and D issues for each accelerator component, studies on the beam dynamics, performance of the Compact ERL as a light source of THz and X-ray. (author)

Investigations of the magnetic structure and the decay of a plasma-gun-generated compact torus

International Nuclear Information System (INIS)

Turner, W.C.; Goldenbaum, G.C.; Granneman, E.H.A.; Hammer, J.H.; Hartman, C.W.; Prono, D.S.; Taska, J.

1983-01-01

The results of a series of experimental measurements of compact toroidal (CT) plasmas produced by a magnetized coaxial plasma gun injecting into a flux-conserving metallic liner are reported. The experiments were performed on the Beta II facility at Lawrence Livermore National Laboratory. The magnetic equilibria are well described by a force-free eigenmode structure that results from an extension of Taylor's theory of the reversed-field pinch. Consideration of helicity conservation during relaxation of the composite plasma-gun flux-conserver system to the final state equilibrium yields theoretical expressions that are compared with the experiment

Optimal III-nitride HEMTs: from materials and device design to compact model of the 2DEG charge density

Science.gov (United States)

Li, Kexin; Rakheja, Shaloo

2017-02-01

In this paper, we develop a physically motivated compact model of the charge-voltage (Q-V) characteristics in various III-nitride high-electron mobility transistors (HEMTs) operating under highly non-equilibrium transport conditions, i.e. high drain-source current. By solving the coupled Schrödinger-Poisson equation and incorporating the two-dimensional electrostatics in the channel, we obtain the charge at the top-of-the-barrier for various applied terminal voltages. The Q-V model accounts for cutting off of the negative momenta states from the drain terminal under high drain-source bias and when the transmission in the channel is quasi-ballistic. We specifically focus on AlGaN and AlInN as barrier materials and InGaN and GaN as the channel material in the heterostructure. The Q-V model is verified and calibrated against numerical results using the commercial TCAD simulator Sentaurus from Synopsys for a 20-nm channel length III-nitride HEMT. With 10 fitting parameters, most of which have a physical origin and can easily be obtained from numerical or experimental calibration, the compact Q-V model allows us to study the limits and opportunities of III-nitride technology. We also identify optimal material and geometrical parameters of the device that maximize the carrier concentration in the HEMT channel in order to achieve superior RF performance. Additionally, the compact charge model can be easily integrated in a hierarchical circuit simulator, such as Keysight ADS and CADENCE, to facilitate circuit design and optimization of various technology parameters.

Particle simulations in toroidal geometry

International Nuclear Information System (INIS)

Aydemir, A.Y.

1992-09-01

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

Cryogenic analysis of forced-cooled, superconducting TF magnets for compact tokamak reactors

International Nuclear Information System (INIS)

Kerns, J.A.; Slack, D.S.; Miller, J.R.

1988-01-01

Current designs for compact tokamak reactors require the toroidal- field (TF) superconducting magnets to produce fields from 10 to 15 T at the winding pack, using high-current densities to high nuclear heat loads (greater than 1 kW/coil in some instances), which are significantly greater than the conduction and radiation heat loads for which cryogenic systems are usually designed. A cryogenic system for the TF winding pack for two such tokamak designs has been verified by performing a detailed, steady-state heat-removal analysis. Helium properties along the forced-cooled conductor flow path for a range of nuclear heat loads have been calculated. The results and implications of this analysis are presented. 12 refs., 6 figs

Axisymmetric toroidal equilibrium with flow and anisotropic pressure

International Nuclear Information System (INIS)

Iacono, R.; Bondeson, A.; Troyon, F.; Gruber, R.

1989-10-01

Axisymmetric toroidal plasma equilibria with mass flows and anisotropic pressure are investigated. The equilibrium system is derived for a general functional form of the pressures, which includes both fluid models, such as the magnetohydrodynamic (MHD) and the double-adiabatic models, and Grad's guiding centre model. This allows for detailed comparisons between the models and clarifies how the 'first hyperbolic region', occurring in the fluid theory when the poloidal flow is of the order of the poloidal sound speed, can be eliminated in guiding centre theory. In the case of a pure toroidal rotation, macroscopic equations of state are derived from the guiding centre model, characterized by a parallel temperature that is constant on each magnetic surface and a perpendicular temperature that varies with the magnetic field. The outward centrifugal shifts of the magnetic axis and of the mass density profile, due to toroidal rotation, are increased by anisotropy. The guiding centre model shows that poloidal flow produces an inward shift of the density profile, in contrast with the MHD result. (author) 1 fig., 1 tab., 17 refs

Impact of ECRH launcher flexibility on NTM stabilization and advanced scenarios in large toroidal configurations as JET plasmas

International Nuclear Information System (INIS)

Nowak, S.; Bruschi, A.; Ramponi, G.; Cirant, S.; Lazzaro, E.; Verhoeven, A.G.A.; Zohm, H.

2003-01-01

A beam-tracing code is used for extensive beam-tracing, ECCD and ECRH profile calculations in ideal JET-like plasmas with the main aim of specifying such crucial parameters for the ECRH launcher as the poloidal and toroidal steering ranges, the permitted error in the various launching angles and the optimal shape of the last mirrors reflecting surfaces. In order to be fusion-relevant, the calculations are performed on ideal target plasmas and equilibrium configurations scaled from real JET shots, selected by the JET-EP ECRH Physics Integration Project. The launching scheme is fully compliant with a launcher designed under the geometric constraints of JET, which consists of 6 to 8 beams arranged in pairs, with four end mirrors steerable both in the poloidal and in the toroidal directions. It is shown that with this arrangement all launching configurations requested by the physics goals of ECRH in a JET-like device are feasible. (authors)

Ballooning instabilities in toroidally linked mirror systems

International Nuclear Information System (INIS)

Hastie, R.J.; Watson, C.J.H.

1977-01-01

This paper examines the stability against ballooning modes of plasma equilibria in toroidally linked mirror configurations consisting of a number of quadrupole minimum-B mirrors linked toroidally. On the basis of the Kruskal-Oberman energy principle, a class of displacements is identified which are potentially unstable, and a necessary criterion for stability is derived. The criterion is obtained from the eigenvalues of an ordinary differential equation, which determines the variation of the displacement along a field line. The coefficients in the equation are determined by the configuration, and by inserting various model configurations, estimates are obtained of the maximum value of β consistent with stability. In cases of interest, quite high β-values are obtained. (author)

Generation of toroidal pre-heat plasma

International Nuclear Information System (INIS)

Ikeda, Nagayasu; Tamaru, Ken; Nagata, Akiyoshi.

1979-01-01

The characteristics of toroidal plasma in the initial stage of electric discharge were investigated. A small toroidal-pinch system was used for the present work. A magnetic probe was used to measure the magnetic field. The time of beginning of discharge was determined by observing the variation of the magnetic field. The initial gas pressure dependence of the induced electric field regions, in which electric discharge can be caused, was studied. It is necessary to increase the initial induced electric field for starting discharge. The delay time of large current discharge was measured, and it was about 2 microsecond. Dependences of the electric fields at the beginning of discharge on the charging voltage of capacitors, on the initial gas pressure, and on the discharge frequency were studied. The formation mechanism of plasma column was analyzed. (Kato, T.)

Self-consistent perturbed equilibrium with neoclassical toroidal torque in tokamaks

International Nuclear Information System (INIS)

Park, Jong-Kyu; Logan, Nikolas C.

2017-01-01

Toroidal torque is one of the most important consequences of non-axisymmetric fields in tokamaks. The well-known neoclassical toroidal viscosity (NTV) is due to the second-order toroidal force from anisotropic pressure tensor in the presence of these asymmetries. This work shows that the first-order toroidal force originating from the same anisotropic pressure tensor, despite having no flux surface average, can significantly modify the local perturbed force balance and thus must be included in perturbed equilibrium self-consistent with NTV. The force operator with an anisotropic pressure tensor is not self-adjoint when the NTV torque is finite and thus is solved directly for each component. This approach yields a modified, non-self-adjoint Euler-Lagrange equation that can be solved using a variety of common drift-kinetic models in generalized tokamak geometry. The resulting energy and torque integral provides a unique way to construct a torque response matrix, which contains all the information of self-consistent NTV torque profiles obtainable by applying non-axisymmetric fields to the plasma. This torque response matrix can then be used to systematically optimize non-axisymmetric field distributions for desired NTV profiles. Published by AIP Publishing.

Barrel Toroid fully charged to nominal field, and it works!

CERN Multimedia

Herman ten Kate

After a few weeks of testing up to intermediate currents, finally, on Thursday evening November 9, the current in the Barrel Toroid was pushed up to its nominal value of 20500 A and even 500 A beyond this value to prove that we have some margin. It went surprisingly well. Of course, the 8 coils forming the toroid were already tested individually at the surface but still, some surprise may have come from those parts added to the toroid in the cavern for the first time like the 8 cryoring sections linking the coils as well as the valve box at the bottom in sector 13 regulating the helium flow or the current lead cryostat on the top in sector 5. No training quenches, nothing to worry about, and the test was concluded with a fast dump triggered at 00:40 in the very early morning of November 10. (left) The toroid current during the evening and night of November 9. (right) The test crew oscillated between fear and hope while looking at the control panels as the current approached 21kA. Big relief was in the...

Compact Visualisation of Video Summaries

Directory of Open Access Journals (Sweden)

Janko Ćalić

2007-01-01

Full Text Available This paper presents a system for compact and intuitive video summarisation aimed at both high-end professional production environments and small-screen portable devices. To represent large amounts of information in the form of a video key-frame summary, this paper studies the narrative grammar of comics, and using its universal and intuitive rules, lays out visual summaries in an efficient and user-centered way. In addition, the system exploits visual attention modelling and rapid serial visual presentation to generate highly compact summaries on mobile devices. A robust real-time algorithm for key-frame extraction is presented. The system ranks importance of key-frame sizes in the final layout by balancing the dominant visual representability and discovery of unanticipated content utilising a specific cost function and an unsupervised robust spectral clustering technique. A final layout is created using an optimisation algorithm based on dynamic programming. Algorithm efficiency and robustness are demonstrated by comparing the results with a manually labelled ground truth and with optimal panelling solutions.

Heating in toroidal plasmas

International Nuclear Information System (INIS)

Canobbio, E.

1981-01-01

This paper reports on the 2nd Joint Grenoble-Varenna International Symposium on Heating in Toroidal Plasmas, held at Como, Italy, from the 3-12 September 1980. Important problems in relation to the different existing processes of heating. The plasma were identified and discussed. Among others, the main processes discussed were: a) neutral beam heating, b) ion-(electron)-cyclotron resonance heating, c) hybrid resonance and low frequency heating

Destabilization of a peeling-ballooning mode by a toroidal rotation in tokamaks

International Nuclear Information System (INIS)

Aiba, N.; Hirota, M.; Tokuda, S.; Furukawa, M.

2009-01-01

Full text: From the viewpoint of the heat load on the divertor, Type-I edge localized mode (ELM) needs to be suppressed or the amplitude of this ELM needs to be reduced. In JT-60U, some experimental results showed that the ELM frequency depends on the toroidal rotation, and the rapid rotation in the counter direction of the plasma current changes from Type-I ELM to Grassy ELM, whose frequency is high and the amplitude is small. Recent experimental and theoretical/numerical studies in a static system have identified that both Type-I and Grassy ELMs are considered ideal magnetohydrodynamic (MHD) modes destabilizing near the plasma surface, called peeling-ballooning modes. To investigate the mechanism of the change of ELM frequency by a toroidal rotation, theoretical and numerical analyses are important for understanding the toroidal rotation effects on the peeling-ballooning mode. Previous works about the toroidal rotation effect on the edge MHD stability have illustrated that the toroidal rotation with shear can destabilize low/intermediate-n (<50) modes but can stabilize high-n modes, where n is the toroidal mode number. The stabilization of the high-n mode can be understood qualitatively in analogy with the infinite-n ballooning mode case. However, the destabilizing mechanism of the low/intermediate-n mode is not still clarified, and to understand the stability property related to ELM suppression/mitigation, it is important to clarify this destabilizing mechanism. In this paper, we investigate numerically the destabilizing effect of a toroidal rotation on the peeling-ballooning mode with a newly developed code MINERVA, which solves the Frieman-Rotenberg equation. Particularly, we pay attention to the effect of the centrifuged force on not only equilibrium but also change of equation of motion. (author)

Heat removal in INTOR via a toroidal limiter

International Nuclear Information System (INIS)

Mioduszewski, P.

1981-01-01

In the present paper the potential of removing about 100 MW of thermal plasma power via a toroidal limiter in INTOR is studied. The heat flux distributions on various limiter configurations are calculated and the thermal response of a graphite tile limiter is estimated on the base of a one-dimensional heat conduction approach. The evaporation rates which have to be expected for the given energy flux densities and radiation cooled graphite tiles are evaluated. According to the present understanding it should be possible to remove 100 MW power from the INTOR plasma via a radiation cooled toroidal limiter. (author)

Compression of toroidal plasma by imploding plasma-liner

International Nuclear Information System (INIS)

Ikuta, Kazunari.

1979-07-01

A new concept of compressing a plasma in a closed magnetic configuration by a version of liner implosion flux compression technique is considered. The liner consists of a dense plasma cylinder, i.e. the plasma-liner. Maximum compression ratio of toroidal plasma is determined just by the initial density ratio of the toroidal plasma to the liner plasma because of the Rayleigh-Taylor instability. A start-up senario of plasma-liner is also proposed with a possible application of this concept to the creation of a burning plasma in reversed field configurations, i.e. burning plasma vortex. (author)

Thermal and electrical joint test for the helical field coils in the Advanced Toroidal Facility

International Nuclear Information System (INIS)

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 0 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

Bi-2223 HTS winding in toroidal configuration for SMES coil

International Nuclear Information System (INIS)

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

2010-01-01

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

Onsager relaxation of toroidal plasmas

International Nuclear Information System (INIS)

Samain, A.; Nguyen, F.

1997-01-01

The slow relaxation of isolated toroidal plasmas towards their thermodynamical equilibrium is studied in an Onsager framework based on the entropy metric. The basic tool is a variational principle, equivalent to the kinetic equation, involving the profiles of density, temperature, electric potential, electric current. New minimization procedures are proposed to obtain entropy and entropy production rate functionals. (author)

Time-dependent simulations of a Compact Ignition Tokamak

International Nuclear Information System (INIS)

Stotler, D.P.; Bateman, G.

1988-05-01

Detailed simulations of the Compact Ignition Tokamak are carried out using a 1-1/2-D transport code. The calculations include time-varying densities, fields, and plasma shape. It is shown that ignition can be achieved in this device if somewhat better than L-mode energy confinement time scaling is possible. We also conclude that the performance of such a compact, short-pulse device can depend greatly on how the plasma is evolved to its flat-top parameters. Furthermore, in cases such as the ones discussed here, where there is not a great deal of ignition margin and the electron density is held constant, ignition ends if the helium ash is not removed. In general, control of the deuterium--tritium density is equivalent to burn control. 48 refs., 15 figs

Search for hyperheavy toroidal nuclear structures formed in Au + Au collisions

International Nuclear Information System (INIS)

Sochocka, A.; Planeta, R.; Starypan, Z.; Benisz, A.; Hachaj, P.; Nicolis, N.G.

2008-01-01

We study the feasibility of an experimental observation of toroidal breakup configurations in Au+Au collisions using the CHIMERA multidetector system. BUU simulations indicate that the threshold energy for toroidal configuration is around 23 MeV/nucleon. The simulations of decay process using the ETNA code indicate the sensitivity of some observables to different studied break-up geometries. (author)

Stationary shear flows in CGL anisotropic toroidal plasmas

International Nuclear Information System (INIS)

Pastukhov, V.P.; Ilgisonis, V.I.

1996-01-01

Recently a general structure of stationary shear flows in toroidal plasmas was obtained in the frame of ideal isotropic-pressure MHD model. The structure of the stationary plasma flows was shown to be determined by a hidden symmetry of MHD equations inherent in the toroidal systems with nested magnetic surfaces. However, the characteristic frequencies of the stationary plasma motion can considerably exceed the collisional frequencies in real plasma experiments. In this case the CGL collisionless MHD model seems to be more adequate than the simplified isotropic-pressure MHD model to describe the stationary plasma flows. In this paper we have generalized our approach to analyze the stationary plasma flows in the frame of the collisionless CGL model. We have found again that the hidden symmetry inherent in the toroidal topology results in two integral invariants which depend on two independent surface functions. The structure of stationary flows for CGL model is still the same as for isotropic MHD, however, the pressure tensor components satisfy a appreciably modifies the steady state force-balance equation. These results are applied to analyze the generalized equilibrium in axisymmetric (tokamak-like) magnetic confinement systems

Eigenvalues of relaxed toroidal plasmas of arbitrary sharp edged cross sections. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

Khalil, Sh M [Plasma Physics and Nuclear Fusion Department, Nuclear Research Center, Atomic Energy Authority, Cairo, (Egypt)

1996-03-01

Relaxed (force-free) toroidal plasmas described by the equations cur 1 B={mu}B, and grad {mu}=O (B is the magnetic field) induces interest in nuclear fusion. Its solution is perceived to describe the gross of the reversed field pinch (RFP), spheromak configuration, current limitation in toroidal plasmas, and others. The parameter {mu} plays an important roll in relaxed states. It cannot exceed the smallest eigenvalue {mu} (min), and that for a toroidal discharge there is a maximum toroidal current which is connected to this value. The values of{mu} were calculated numerically, using the methods of collocation points, for toroids of arbitrary aspect ratio {alpha} ({alpha} = R/a, ratio of major/minor radii of tokamak) and arbitrary curved cross-sections (circle, ellipse, cassini, and D-shaped). The aim of present work is to prove the applicability of the numerical methods for calculating the eigenvalues for toroidal plasmas having sharp edged cross sections and arbitrary aspect ratio. The lowest eigenvalue {mu} (min), satisfy the boundary condition {beta} .n = O (or RB. = O) for which the toroidal flux are calculated. These are the zero field eigenvalues of the equation cur 1 b={mu}B. The poloidal magnetic field lines corresponding to different cross sections are shown by plotting the boundary condition B.n=O. The plots showed good fulfillment of the boundary condition along the whole boundaries of different cross sections. Dependence of eigenvalues {mu}a on aspect ratio {alpha} is also obtained. Several runs of the programme with various wave numbers K showed that {mu}a is very insensitive to the choice of K. 8 figs.

The Compact Ignition Tokamak

International Nuclear Information System (INIS)

Schmidt, J.

1987-01-01

The author discusses his lab's plan for completing the Compact Ignition Tokamak (CIT) conceptual design during calendar year 1987. Around July 1 they froze the subsystem envelopes on the device to continue with the conceptual design. They did this by formalizing a general requirements document. They have been developing the management plan and submitted a version to the DOE July 10. He describes a group of management activities. They released the vacuum vessel Request For Proposals (RFP) on August 5. An RFP to do a major part of the system engineering on the device is being developed. They intend to assemble the device outside of the test cell, then move it into the the test cell, install it there, and bring to the test cell many of the auxiliary facilities from TFTR, for example, power supplies

Poloidal and toroidal plasmons and fields of multilayer nanorings

International Nuclear Information System (INIS)

Garapati, K. V.; Salhi, M.; Kouchekian, S.; Siopsis, G.

2017-01-01

Composite and janus type metallodielectric nanoparticles are increasingly considered as a means to control the spatial and temporal behavior of electromagnetic fields in diverse applications such as coupling to quantum emitters, achieving invisibility cloaks, and obtaining quantum correlations between qubits. We investigate the surface modes of a toroidal nanostructure and obtain the canonical plasmon dispersion relations and resonance modes for arbitrarily layered nanorings. Unlike particle plasmon eigenmodes in other geometries, the amplitudes of the eigenmodes of tori exhibit a distinct forward and backward coupling. We present the plasmon dispersion relations for several relevant toroidal configurations in the quasistatic limit and obtain the dominant retarded dispersion relations of a single ring for comparison, discuss mode complementarity and hybridization, and introduce two new types of toroidal particles in the form of janus nanorings. The resonance frequencies for the first few dominant modes of a ring composed of plasmon supporting materials such as gold, silver, and aluminum are provided and compared to those for a silicon ring. A generalized Green's function is obtained for multilayer tori allowing for calculation of the scattering response to interacting fields. Employing the Green's function, the scalar electric potential distribution corresponding to individual poloidal and toroidal modes in response to an arbitrarily polarized external field and the field of electrons is obtained. The results are applied to obtain the local density of states and decay rate of a dipole near the center of the torus.

Poloidal and toroidal plasmons and fields of multilayer nanorings

Science.gov (United States)

Garapati, K. V.; Salhi, M.; Kouchekian, S.; Siopsis, G.; Passian, A.

2017-04-01

Composite and janus type metallodielectric nanoparticles are increasingly considered as a means to control the spatial and temporal behavior of electromagnetic fields in diverse applications such as coupling to quantum emitters, achieving invisibility cloaks, and obtaining quantum correlations between qubits. We investigate the surface modes of a toroidal nanostructure and obtain the canonical plasmon dispersion relations and resonance modes for arbitrarily layered nanorings. Unlike particle plasmon eigenmodes in other geometries, the amplitudes of the eigenmodes of tori exhibit a distinct forward and backward coupling. We present the plasmon dispersion relations for several relevant toroidal configurations in the quasistatic limit and obtain the dominant retarded dispersion relations of a single ring for comparison, discuss mode complementarity and hybridization, and introduce two new types of toroidal particles in the form of janus nanorings. The resonance frequencies for the first few dominant modes of a ring composed of plasmon supporting materials such as gold, silver, and aluminum are provided and compared to those for a silicon ring. A generalized Green's function is obtained for multilayer tori allowing for calculation of the scattering response to interacting fields. Employing the Green's function, the scalar electric potential distribution corresponding to individual poloidal and toroidal modes in response to an arbitrarily polarized external field and the field of electrons is obtained. The results are applied to obtain the local density of states and decay rate of a dipole near the center of the torus.

Compact device to heat up a liquid metal

International Nuclear Information System (INIS)

Blanc, R.; Pelloux, L.

1981-01-01

Device for heating a liquid metal, sodium for instance, this device being in one piece and capable of being introduced in one go into the tank containing the liquid metal and comprising heating rods and an electromagnetic pump [fr

Manufacturing of Mn-Zn ferrite transformer cores

International Nuclear Information System (INIS)

Waqas, H.; Qureshi, A.H.; Hussain, N.; Ahmed, N.

2012-01-01

The present work is related to the development of soft ferrite transformer cores, which are extensively used in electronic devices such as switch mode power supplies, electromagnetic devices, computers, amplifiers etc. Mn-Zn Ferrite (soft ferrite) powders were prepared by conventional mixed oxide and auto combustion routes. These powders were calcined and then pressed in toroid shapes. Sintering was done at different temperatures to develop desired magnetic phase. Impedance resistance of sintered toroid cores was measured at different frequencies. Results revealed that Mn-Zn Ferrite cores synthesized by auto combustion route worked more efficiently in a high frequency range i.e. > 2MHz than the cores developed by conventional mixed oxide method. It was noticed that compact size, light weight and high impedance resistance are the prime advantages of auto combustion process which supported the performance of core in MHz frequency range. Furthermore, these compact size cores were successfully tested in linear pulse amplifier circuit of Pakistan Atomic Research Reactor-I. The fabrication of soft ferrite (Mn-Zn Ferrite) cores by different processing routes is an encouraging step towards indigenization of ferrite technology. (Orig./A.B.)

Tokamak configuration analysis with the method of toroidal multipoles

International Nuclear Information System (INIS)

Micozzi, P.; Alladio, F.; Crisanti, F.; Marinucci, M.; Tanga, A.

1989-01-01

In the study of tokamak machines able to sustain plasmas of thermonuclear interest (JIT, IGNITOR, NET, CIT, ET), there is a strong quest for engineering optimization of the circuital components close to the plasma. We have developed a semianalytical axisymmetric MHD equilibrium code based on the technique of the poloidal ψ flux function expansion in toroidal harmonic series. This code is able to optimize the necessary currents in the poloidal circuits in order to sustain a plasma of fixed shape (also x-point configuration), toroidal current and poloidal β. (author) 4 refs., 4 figs

Complete suppression of Pfirsch-Schlueter current in a toroidal l=3 stellarator

International Nuclear Information System (INIS)

Sato, Yasuhiko; Wakatani, Masahiro; Yokoyama, Masayuki; Pustovitov, V.D.

1999-10-01

Pfirsch-Schlueter (P-S) current is an inherent property of a finite pressure toroidal equilibrium of tokamak and stellarator. However, it was pointed out recently (V.D. Pustovitov, Nuclear Fusion 36 (1996) 583) that the P-S current would be suppressed completely if the external vertical field could be adjusted to satisfy the condition Ω= in an l=3 stellarator. Here Ω= 2 >/B 0 2 -2ε cosθ, l is a pole number, |B tilde| the vacuum helical magnetic field, B 0 the toroidal field, ε the inverse aspect ratio, θ the poloidal angle and denotes the average over the toroidal angle. An example of such a stellarator equilibrium is presented in this paper. For this stellarator equilibrium, behavior of rotational transform and Boozer magnetic spectrum is clarified when the pressure is increased. Both formation of helical magnetic axis and reduction of toroidal curvature are important ingredients to reduce the P-S current. However, the collisionless particle confinement is not improved in this example. (author)

Structural design of the toroidal configuration of the HTS SMES cooling system

International Nuclear Information System (INIS)