An analogy of a magnetic mirror in mechanics

International Nuclear Information System (INIS)

Lal, Amit; Badiger, Shrikrishna M

2005-01-01

The motion of a charged particle in a magnetic mirror device is compared to the motion of a bead spiralling into a smooth hollow cone. The complete solution of the motion of the bead is derived and physical aspects of the solution obtained are discussed. Similarities between the motion of the bead and that of a charged particle in a magnetic mirror device are pointed out. The effort is primarily aimed at enhancing the physical understanding of the mechanics of a charged particle in a magnetic mirror device and secondarily at proposing an equivalent mechanics problem, devoid of any electro-dynamical aspect but still possessing all the interesting features of the original problem. The proposed problem can be taught at upper-division undergraduate level

Mirror structures above and below the linear instability threshold: Cluster observations, fluid model and hybrid simulations

Directory of Open Access Journals (Sweden)

V. Génot

2009-02-01

Full Text Available Using 5 years of Cluster data, we present a detailed statistical analysis of magnetic fluctuations associated with mirror structures in the magnetosheath. We especially focus on the shape of these fluctuations which, in addition to quasi-sinusoidal forms, also display deep holes and high peaks. The occurrence frequency and the most probable location of the various types of structures is discussed, together with their relation to local plasma parameters. While these properties have previously been correlated to the β of the plasma, we emphasize here the influence of the distance to the linear mirror instability threshold. This enables us to interpret the observations of mirror structures in a stable plasma in terms of bistability and subcritical bifurcation. The data analysis is supplemented by the prediction of a quasi-static anisotropic MHD model and hybrid numerical simulations in an expanding box aimed at mimicking the magnetosheath plasma. This leads us to suggest a scenario for the formation and evolution of mirror structures.

Plasma cleaning of ITER First Mirrors in magnetic field

Energy Technology Data Exchange (ETDEWEB)

Moser, Lucas, E-mail: lucas.moser@unibas.ch [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Steiner, Roland [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Leipold, Frank; Reichle, Roger [ITER Organization, Route de Vinon-sur-Verdon, 13115 St Paul-lez-Durance (France); Marot, Laurent; Meyer, Ernst [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

2015-08-15

To avoid reflectivity losses in ITER’s optical diagnostic systems, plasma sputtering of metallic First Mirrors is foreseen in order to remove deposits coming from the main wall (mainly beryllium and tungsten). Therefore plasma cleaning has to work on large mirrors (up to a size of 200 × 300 mm) and under the influence of strong magnetic fields (several Tesla). This work presents the results of plasma cleaning of aluminium and aluminium oxide (used as beryllium proxy) deposited on molybdenum mirrors. Using radio frequency (13.56 MHz) argon plasma, the removal of a 260 nm mixed aluminium/aluminium oxide film deposited by magnetron sputtering on a mirror (98 mm diameter) was demonstrated. 50 nm of pure aluminium oxide were removed from test mirrors (25 mm diameter) in a magnetic field of 0.35 T for various angles between the field lines and the mirrors surfaces. The cleaning efficiency was evaluated by performing reflectivity measurements, Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy.

Magnet system for a thermal barrier Tandem Mirror Reactor

International Nuclear Information System (INIS)

Kim, N.S.; Conn, R.W.

1981-01-01

The magnet system for a thermal barrier D-D tandem mirror reactor has been studied as part of the UCLA tandem mirror reactor design study SATYR. Three main considerations in designing the SATYR magnet system are to obtain the desired field strength variation throughout the system, to have proper space for plasma and neutron shielding, and to satisfy the MHD stability to achieve maximum central cell /beta/. Due to the importance and the complexity, the 'internal' field reversal magnet is the main concern in the entire magnet system for SATYR. Two different magnet designs, a non-uniform current density solenoid and a higher-order solenoid, are discussed. Coil levitation for the internal field reversal magnet has been analyzed

Tandem mirror magnet system for the mirror fusion test facility

International Nuclear Information System (INIS)

Bulmer, R.H.; Van Sant, J.H.

1980-01-01

The Tandem Mirror Fusion Test Facility (MFTF-B) will be a large magnetic fusion experimental facility containing 22 supercounducting magnets including solenoids and C-coils. State-of-the-art technology will be used extensively to complete this facility before 1985. Niobium titanium superconductor and stainless steel structural cases will be the principle materials of construction. Cooling will be pool boiling and thermosiphon flow of 4.5 K liquid helium. Combined weight of the magnets will be over 1500 tonnes and the stored energy will be over 1600 MJ. Magnetic field strength in some coils will be more than 8 T. Detail design of the magnet system will begin early 1981. Basic requirements and conceptual design are disclosed in this paper

Magnetic mirrors: history, results, and future prospects

International Nuclear Information System (INIS)

Beklemishev, A.D.; Ivanov, A.A.; Kruglyakov, E.P.; Burdakov, A.V.; Ivanov, A.A.; Beklemishev, A.D.; Ivanov, A.A.; Burdakov, A.V.

2012-01-01

The evolution of open traps brought them from simple solenoids to highly sophisticated and huge tandem mirrors with quadrupole magnetic stabilizers. They tried to compete with toroidal devices using ambipolar confinement and thermal barriers, but were too late and failed, and are almost extinct. A side branch of open traps went for simplicity and good fast-ion confinement inherent in axially symmetric mirrors. Since simplicity means lower cost of construction and servicing, and lower engineering and materials demands, such type of traps might still have an edge. Axially symmetric mirrors at the Budker Institute of Nuclear Physics in Novosibirsk currently represent the front line of mirror research. We discuss recent experimental results from the multiple-mirror trap, GOL-3, and the gas-dynamic trap, GDT. The next step in this line of research is the GDMT program that will combine the GDT-style fast-ion-dominated central mirror with multiple-mirror end plugs. This superconducting device will be modular and built in stages. The first stage, GDMT-T, will be based on 5m, 7T superconducting solenoid (multiple-mirror plug of the full device). Its 3-year scientific program is oriented primarily on PMI studies.

Topics on the formation and stability of magnetic-mirror-confined plasmas

International Nuclear Information System (INIS)

Wickham, M.G.

1981-01-01

We have investigated two methods of creating a magnetic mirror confined plasma. The first method used the direct cross-field injection of a potassium plasma into a magnetic mirror, and the second applied ion-cyclotron-resonance heating (ICRH) to a barium Q-machine plasma in a simple axisymmetric mirror field. The latter procedure provided a plasma which was particularly suitable for the investigation of MHD stability and kinetic microstability

Axisymmetric magnetic mirrors for plasma confinement. Recent development and perspectives

International Nuclear Information System (INIS)

Kruglyakov, E.P.; Dimov, G.I.; Ivanov, A.A.; Koidan, V.S.

2003-01-01

Mirrors are the only one class of fusion systems which completely differs topologically from the systems with closed magnetic configurations. At present, three modern types of different mirror machines for plasma confinement and heating exist in Novosibirsk (Gas Dynamic Trap,- GDT, Multi-mirror,- GOL-3, and Tandem Mirror,- AMBAL-M). All these systems are attractive from the engineering point of view because of very simple axisymmetric geometry of magnetic configurations. In the present paper, the status of different confinement systems is presented. The experiments most crucial for the mirror concept are described such as a demonstration of different principles of suppression of electron heat conductivity (GDT, GOL-3), finding of MHD stable regimes of plasma confinement in axisymmetric geometry of magnetic field (GDT, AMBAL-M), an effective heating of a dense plasma by relativistic electron beam (GOL-3), observation of radial diffusion of quiescent plasma with practically classical diffusion coefficient (AMBAL-M), etc. It should be mentioned that on the basis of the GDT it is possible to make a very important intermediate step. Using 'warm' plasma and oblique injection of fast atoms of D and T one can create a powerful 14 MeV neutron source with a moderate irradiation area (about 1 square meter) and, accordingly, with low tritium consumption. The main plasma parameters achieved are presented and the future perspectives of different mirror machines are outlined. (author)

Irradiated radiation dose measurements of multilayer mirrors and permanent magnets used at FELI facilities

International Nuclear Information System (INIS)

Wakisaka, K.; Tongu, H.; Okuma, S.; Oshita, E.; Wakita, K.; Takii, T.; Tomimasu, Takio

1997-01-01

Recently the operation time of the free electron laser (FEL) user's facilities is close on three thousand hours per year. Cavity mirrors of their optical resonators and permanent magnets of their undulators are used under high intensity radiation field along their high current electron beam lines. Among these mirrors and permanent magnets, multilayer mirrors and Nd-Fe-B permanent magnets are not so strong against radiation damage compared with Au-coated copper mirrors and Sm-Co permanent magnets. A radiation damage on Ta 2 O 5 /SiO 2 mirrors was found for the first time after about fifty hours visible FEL operation at the FELI. The damage is due to irradiated bremsstrahlung and intracavity FEL. However, radiation damages on Nd-Fe-B permanent magnets were already reported compared with Sm-Co ones using high energy neutrons, protons, deuterons and 60 Coγ-rays. Mixed irradiation effects of 85-MeV electrons, bremsstrahlung and 60 Coγ-rays and of 17-MeV electrons and 60 Coγ-rays were also studied. The latest results show that the magnetic flux loss of Nd-Fe-B is 2% at an absorbed dose of 10 MGy. The present work was carried out to study the irradiated dose distributions near the multilayer mirrors and Nd-Fe-B permanent magnets with thermoluminescence dosimeters (TLDs). The irradiated dose to the cavity mirrors used in Linac-based FEL experiment is estimated to be 0.3 MGray for fifty hours irradiation. The irradiated dose to the Nd-Fe-B magnets is estimated to be 16 MGray for 2 thousand hours operation. The decrease of their magnetic flux due to 16 MGray is estimated to be about 3%. These dose monitorings are useful to reduce irradiated dosages to the mirrors and the permanent magnets as low as possible and to estimate their safety lifetimes. (author)

Magnet and conductor developments for the Mirror Fusion Program

International Nuclear Information System (INIS)

Cornish, D.N.

1981-01-01

The conductor development and the magnet design and construction for the MFTF are described. Future plans for the Mirror Program and their influence on the associated superconductor development program are discussed. Included is a summary of the progress being made to develop large, high-field, multifilamentary Nb 3 Sn superconductors and the feasibility of building a 12-T yin-yang set of coils for the machine to follow MFTF. In a further look into the future, possible magnetic configurations and requirements for mirror reactors are surveyed

Demonstration of Focusing Wolter Mirrors for Neutron Phase and Magnetic Imaging

Directory of Open Access Journals (Sweden)

Daniel S. Hussey

2018-03-01

Full Text Available Image-forming focusing mirrors were employed to demonstrate their applicability to two different modalities of neutron imaging, phase imaging with a far-field interferometer, and magnetic-field imaging through the manipulation of the neutron beam polarization. For the magnetic imaging, the rotation of the neutron polarization in the magnetic field was measured by placing a solenoid at the focus of the mirrors. The beam was polarized upstream of the solenoid, while the spin analyzer was situated between the solenoid and the mirrors. Such a polarized neutron microscope provides a path toward considerably improved spatial resolution in neutron imaging of magnetic materials. For the phase imaging, we show that the focusing mirrors preserve the beam coherence and the path-length differences that give rise to the far-field moiré pattern. We demonstrated that the visibility of the moiré pattern is modified by small angle scattering from a highly porous foam. This experiment demonstrates the feasibility of using Wolter optics to significantly improve the spatial resolution of the far-field interferometer.

Experimental investigation of plasma sheaths in magnetic mirror and cusp configurations

Science.gov (United States)

Jiang, Zhengqi; Wei, Zi-an; Ma, J. X.

2017-11-01

Sheath structures near a metal plate in a magnetized plasma were experimentally investigated in magnetic mirror and cusp configurations. Plasma parameters and the sheath potential distributions were probed by a planar and an emissive probe, respectively. The measured sheath profiles in the mirror configuration show that the sheath thickness first decreases and then increases when the magnetic strength is raised. A magnetic flux-tube model was used to explain this result. In the cusp configuration, the measured sheath thickness decreases with the increase of the coil current creating the magnetic cusp. However, when normalized by the electron Debye length, the dependence of the sheath thickness on the coil current is reversed.

Optimum condition for spatial ion cyclotron resonance in a multiple magnetic mirror field

International Nuclear Information System (INIS)

Mieno, Tetsu; Hatakeyama, Rikizo; Sato, Noriyoshi

1988-01-01

A Spatial cyclotron resonance of ion beams passing through a multiple magnetic mirror field is investigated experimentally by varying parameters of the multiple mirror field. The optimum resonance condition is realized with a decrease in the cell length of the multiple mirror along the beams to satisfy the local condition of the spatial ion cyclotron resonance. The results show a remarkable increase of nonadiabatic transfer of the beam energy into the transverse direction to the magnetic field. (author)

Experiments on the injection, confinement, and ejection of electron clouds in a magnetic mirror

International Nuclear Information System (INIS)

Eckhouse, S.; Fisher, A.; Rostoker, N.

1978-01-01

A cloud of (5 to 10 keV) electrons is injected into a magnetic mirror field. The magnetic field rises in 40--120 μsec to a maximum of 10 kG. Two methods of injection were tried: In the first, the injector is located at the mirror midplane and electrons are injected perpendicular to the magnetic field lines. In the second scheme, the injector is located near the mirror maximum. Up to about 10 11 electrons were trapped in both schemes with a mean kinetic energy of 0.3 MeV. Measured confinement time is limited only by the magnetic field decay time. The compressed electron cloud executes electrostatic oscillations. The frequency of the oscillation is proportional to the number of electrons trapped, and it is independent of the value of the magnetic field and the initial electron energy. The electron cloud was ejected along the mirror axis and properties of the ejected electron cloud were measured by x-ray pulses from bremstrahlung of electrons on the vacuum system wall and by collecting electrons on a Faraday cup

Non-linear ultrasonic time-reversal mirrors in NDT

Czech Academy of Sciences Publication Activity Database

Převorovský, Zdeněk

-, č. 4 (2012), s. 4-4 [World Conference on Nondestructive Testing /18./. 16.4.2012-20.4.2012, Durban] R&D Projects: GA MPO(CZ) FR-TI1/274; GA MPO(CZ) FR-T1/198; GA ČR(CZ) GAP104/10/1430 Institutional research plan: CEZ:AV0Z2076919 Keywords : non-linear ime reversal mirror * ultrasonic techniques * ESAM Subject RIV: BI - Acoustics http://www.academia-ndt.org/Downloads/AcademiaNews4.pdf

Cluster observations of trapped ions interacting with magnetosheath mirror modes

Directory of Open Access Journals (Sweden)

J. Soucek

2011-06-01

Full Text Available Mirror modes are among the most intense low frequency plasma wave phenomena observed in the magnetosheaths of magnetized planets. They appear as large amplitude non-propagating fluctuations in the magnetic field magnitude and plasma density. These structures are widely accepted to represent a non-linear stage of the mirror instability, dominant in plasmas with large ion beta and a significant ion temperature anisotropy T⊥/T∥>1. It has long been recognized that the mirror instability both in the linear and non-linear stage is a kinetic process and that the behavior of resonant particles at small parallel velocities is crucial for its development and saturation. While the dynamics of the instability and the effect of trapped particles have been studied extensively in theoretical models and numerical simulations, only spurious observations of the trapped ions were published to date. In this work we used data from the Cluster spacecraft to perform the first detailed experimental study of ion velocity distribution associated with mirror mode oscillations. We show a conclusive evidence for the predicted cooling of resonant ions at small parallel velocities and heating of trapped ions at intermediate pitch angles.

Generation of Electron Whistler Waves at the Mirror Mode Magnetic Holes: MMS Observations and PIC Simulation

Science.gov (United States)

Ahmadi, N.; Wilder, F. D.; Usanova, M.; Ergun, R.; Argall, M. R.; Goodrich, K.; Eriksson, S.; Germaschewski, K.; Torbert, R. B.; Lindqvist, P. A.; Le Contel, O.; Khotyaintsev, Y. V.; Strangeway, R. J.; Schwartz, S. J.; Giles, B. L.; Burch, J.

2017-12-01

The Magnetospheric Multiscale (MMS) mission observed electron whistler waves at the center and at the gradients of magnetic holes on the dayside magnetosheath. The magnetic holes are nonlinear mirror structures which are anti-correlated with particle density. We used expanding box Particle-in-cell simulations and produced the mirror instability magnetic holes. We show that the electron whistler waves can be generated at the gradients and the center of magnetic holes in our simulations which is in agreement with MMS observations. At the nonlinear regime of mirror instability, the proton and electron temperature anisotropy are anti-correlated with the magnetic hole. The plasma is unstable to electron whistler waves at the minimum of the magnetic field structures. In the saturation regime of mirror instability, when magnetic holes are dominant, electron temperature anisotropy develops at the edges of the magnetic holes and electrons become isotropic at the magnetic field minimum. We investigate the possible mechanism for enhancing the electron temperature anisotropy and analyze the electron pitch angle distributions and electron distribution functions in our simulations and compare it with MMS observations.

Magnet system of the ''AMBAL'' experimental trap with ambipolar mirrors

International Nuclear Information System (INIS)

Dimov, G.I.; Lysyanskij, P.B.; Tadber, M.V.; Timoshin, I.Ya.; Shrajner, K.K.

1982-01-01

A magnet system of the ''AMBAL'' ambipolar trap under construction is described. The trap magnetic field configuration, geometry of the main coils and diagram of the whole device magnet system are outlined. Drift surface cross sections in the equatorial plane of the ring mirror device, in the median plane and at different distances from the trap median plane are presented. The magnet system design is described in brief

Effect of Magnetic Mirror on the Asymmetry of the Radial Profile of Near-Wall Conductivity in Hall Thrusters

International Nuclear Information System (INIS)

Yu Daren; Liu Hui; Fu Haiyang

2009-01-01

Considering the actual magnetic field configuration in a Hall thruster, the effect of magnetic mirror on the radial profile of near-wall conductivity (NWC) is studied in this paper. The plasma electron dynamic process is described by the test particle method. The Monte Carlo scheme is used to solve this model. The radial profile of electron mobility is obtained and the role of magnetic mirror in NWC is analysed both theoretically and numerically. The numerical results show that the electron mobility peak due to NWC is inversely proportional to the magnetic mirror ratio and the asymmetry of electron mobility along the radial direction gets greater when the magnetic mirror is considered. This effect indicates that apart from the disparity in the magnetic field strength, the difference in the magnetic mirror ratio near the inner and outer walls would actually augment the asymmetry of the radial profile of NWC in Hall thrusters.

Tunable system for production of mirror and cusp configurations using chassis of permanent magnets

Science.gov (United States)

Hyde, Alexander; Bushmelov, Maxim; Batishchev, Oleg

2018-03-01

Compact arrays of permanent magnets have shown promise as replacements for electromagnets in applications requiring magnetic cusps and mirrors. An adjustable system capable of suspending and translating a pair of light, nonmagnetic chassis carrying such sources of magnetic field has been designed and constructed. Using this device to align two cylindrical chassis, strong solenoid-like domains of field, as well as classic biconic cusp and magnetic mirror topologies, are generated. Employing a pair of ring-shaped chassis instead, the superposition of their naturally-emitted cusps is demonstrated to produce sextupolar and octupolar magnetic fields.

Lunar remnant magnetic field mapping from orbital observations of mirrored electrons

Energy Technology Data Exchange (ETDEWEB)

McCoy, J E [National Aeronautics and Space Administration, Houston, Tex. (USA). Johnson Space Center; Anderson, K A; Lin, R P; Howe, H C; McGuire, R E [California Univ., Berkeley (USA). Space Sciences Lab.

1975-09-01

Areas of lunar surface magnetic field are observed to ''mirror'' low energy electrons present in the normal lunar space environment. The ambient electrons provide, in effect, a probe along the ambient magnetic field lines down to the lunar surface for remote sensing of the presence of surface fields. Use of the on-board vector magnetometer measurements of the ambient magnetic field orientation allows accurate projection of such mapping onto the lunar surface. Preliminary maps of the lunar surface magnetic areas underlying the orbit of the ''Particles and Fields Satellite deployed from Apollo 16'' have been generated, obtaining 40% coverage from partial data to demonstrate feasibility of the technique. These maps reveal many previously unreported areas of surface magnetism. The method is sensitive to fields of less than 0.1..gamma.. at the surface. The surface field regions observed are generally due to sources smaller than 10-50km in size, although many individual regions are often so close together as to give much larger regions of effectively continuous mirroring. Absence of consistent mirroring by any global field places an upper limit on the size of any net lunar dipole moment of less than 10/sup 10/..gamma..km/sup 3/. Much additional information regarding the magnetic regions can be obtained by correlated analysis of both the electron return and vector magnetometer measurements at orbital altitude, the two techniques providing each other with directly complimentary measurements at the satellite and along the ambient field lines to the surface.

Mirror Instability in the Turbulent Solar Wind

Energy Technology Data Exchange (ETDEWEB)

Hellinger, Petr [Astronomical Institute, CAS, Bocni II/1401,CZ-14100 Prague (Czech Republic); Landi, Simone; Verdini, Andrea; Franci, Luca [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze Largo E. Fermi 2, I-50125 Firenze (Italy); Matteini, Lorenzo, E-mail: petr.hellinger@asu.cas.cz [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

2017-04-01

The relationship between a decaying strong turbulence and the mirror instability in a slowly expanding plasma is investigated using two-dimensional hybrid expanding box simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly polarized, random-phase Alfvénic fluctuations that have energy equipartition between kinetic and magnetic fluctuations and a vanishing correlation between the two fields. A turbulent cascade rapidly develops, magnetic field fluctuations exhibit a Kolmogorov-like power-law spectrum at large scales and a steeper spectrum at sub-ion scales. The imposed expansion (taking a strictly transverse ambient magnetic field) leads to the generation of an important perpendicular proton temperature anisotropy that eventually drives the mirror instability. This instability generates large-amplitude, nonpropagating, compressible, pressure-balanced magnetic structures in a form of magnetic enhancements/humps that reduce the perpendicular temperature anisotropy.

Diode array pumped, non-linear mirror Q-switched and mode-locked ...

Indian Academy of Sciences (India)

A non-linear mirror consisting of a lithium triborate crystal and a dichroic ... effects such as all-optical switching [7,8], nearly degenerate four-wave mixing [9,10], .... is driven by a radio frequency signal of 27.2MHz with a modulation available in.

Axisymmetric Magnetic Mirror Fusion-Fission Hybrid

Energy Technology Data Exchange (ETDEWEB)

Moir, R. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martovetsky, N. N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Molvik, A. W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simonen, T. C. [Univ. of California, Berkeley, CA (United States)

2011-05-13

The achieved performance of the gas dynamic trap version of magnetic mirrors and today’s technology we believe are sufficient with modest further efforts for a neutron source for material testing (Q=P_fusion/P_input~0.1). The performance needed for commercial power production requires considerable further advances to achieve the necessary high Q>>10. An early application of the mirror, requiring intermediate performance and intermediate values of Q~1 are the hybrid applications. The Axisymmetric Mirror has a number of attractive features as a driver for a fusion-fission hybrid system: geometrical simplicity, inherently steady-state operation, and the presence of the natural divertors in the form of end tanks. This level of physics performance has the virtue of low risk and only modest R&D needed and its simplicity promises economy advantages. Operation at Q~1 allows for relatively low electron temperatures, in the range of 4 keV, for the DT injection energy ~ 80 keV. A simple mirror with the plasma diameter of 1 m and mirror-to-mirror length of 35 m is discussed. Simple circular superconducting coils are based on today’s technology. The positive ion neutral beams are similar to existing units but designed for steady state. A brief qualitative discussion of three groups of physics issues is presented: axial heat loss, MHD stability in the axisymmetric geometry, microstability of sloshing ions. Burning fission reactor wastes by fissioning actinides (transuranics: Pu, Np, Am, Cm, .. or just minor actinides: Np, Am, Cm, …) in the hybrid will multiply fusion’s energy by a factor of ~10 or more and diminish the Q needed to less than 1 to overcome the cost of recirculating power for good economics. The economic value of destroying actinides by fissioning is rather low based on either the cost of long-term storage or even deep geologic disposal so most of the revenues of hybrids will come from electrical power. Hybrids that obtain revenues from

Design for the magnetic field requirements of the tandem mirror experiment

International Nuclear Information System (INIS)

Chen, F.K.; Chargin, A.K.; Denhoy, B.S.; Waugh, A.F.

1977-01-01

The tandem mirror magnetic geometry is described, followed by an analysis of the magnet set designed to meet the requirements of the TMX experiment. The final magnet line-up is composed of a baseball coil with two C coils for each plug, six solenoidal coils for the central cell, and two RC coils plus one octupole coil for each transition

Simulation of the magnetic mirror effect on a beam of positrons

CERN Document Server

Boursette, Delphine

2014-01-01

I simulated a beam of positrons at the entrance of a 5 Tesla magnet for the Aegis experiment. The goal was to show how many positrons are lost because of the magnetic mirror effect. To do my simulation, I used Comsol to create the magnetic field map and Geant4 to draw the trajectories of the positrons in this field map.

Simulation of magnetic holes formation in the magnetosheath

Science.gov (United States)

Ahmadi, Narges; Germaschewski, Kai; Raeder, Joachim

2017-12-01

Magnetic holes have been frequently observed in the Earth's magnetosheath and are believed to be the consequence of the nonlinear evolution of the mirror instability. Mirror mode perturbations mainly form as magnetic holes in regions where the plasma is marginally mirror stable with respect to the linear instability criterion. We present an expanding box particle-in-cell simulation to mimic the changing conditions in the magnetosheath as the plasma is convected through it that produces mirror mode magnetic holes. We show that in the initial nonlinear evolution, where the plasma conditions are mirror unstable, the magnetic peaks are dominant, while later, as the plasma relaxes toward marginal stability, the fluctuations evolve into deep magnetic holes. While the averaged plasma parameters in the simulation remain close to the mirror instability threshold, the local plasma in the magnetic holes is highly unstable to mirror instability and locally mirror stable in the magnetic peaks.

Technology requirements for fusion--fission reactors based on magnetic-mirror confinement

International Nuclear Information System (INIS)

Moir, R.W.

1978-01-01

Technology requirements for mirror hybrid reactors are discussed. The required 120-keV neutral beams can use positive ions. The magnetic fields are 8 T or under and can use NbTi superconductors. The value of Q (where Q is the ratio of fusion power to injection power) should be in the range of 1 to 2 for economic reasons relating to the cost of recirculating power. The wall loading of 14-MeV neutrons should be in the range of 1 to 2 MW/m 2 for economic reasons. Five-times higher wall loading will likely be needed if fusion reactors are to be economical. The magnetic mirror experiments 2XIIB, TMX, and MFTF are described

Production of muons for fusion catalysis in a magnetic mirror configuration. Revision 1

International Nuclear Information System (INIS)

Moir, R.W.; Chapline, G.F. Jr.

1986-01-01

For muon-catalyzed fusion to be of practical interest, a very efficient means of producing muons must be found. We describe a scheme for producing muons that may be more energy efficient than any heretofore proposed. There are, in particular, some potential advantages of creating muons from collisions of high energy tritons confined in a magnetic mirror configuration. If one could catalyze 200 fusions per muon and employ a uranium blanket that would multiply the neutron energy by a factor of 10, one might produce electricity with an overall plant efficiency (ratio of electric energy produced to nuclear energy released) approaching 30%. One possible near term application of a muon-producing magnetic-mirror scheme would be to build a high-flux neutron source for radiation damage studies. The careful arrangement of triton orbits will result in many of the π - 's being produced near the axis of the magnetic mirror. The pions quickly decay into muons, which are transported into a small (few-cm-diameter) reactor chamber producing approximately 1-MW/m 2 neutron flux on the chamber walls, using a laboratory accelerator and magnetic mirror. The costs of construction and operation of the triton injection accelerator probably introduces most of the uncertainty in the viability of this scheme. If a 10-μA, 600 MeV neutral triton accelerator could be built for less than $100 million and operated cheaply enough, one might well bring muon-catalyzed fusion into practical use

U. S. Mirror Program

International Nuclear Information System (INIS)

Fowler, T.K.

1978-01-01

The mirror approach is now the principal alternate to the tokamak in the U.S. magnetic fusion energy program. The program is now focused on two new concepts that can obtain high values of Q, defined as the ratio of fusion power output to the neutral beam power injected to sustain the reaction. These are the tandem mirror and field reversed mirror concepts. Theoretically both concepts should be able to attain Q = 5 or more, as compared with Q approximately 1 in previous mirror designs. Success with either or both of these approaches would point the way toward fusion power plants with many attractive features. The linear geometry of mirror systems offers a distinct alternative to the toroidal tokamak. As a direct consequence of this difference in geometry, it is generally possible to build mirror systems in smaller units of modular construction that can probably be made to operate in steady-state. During the next 5 years the main mirror facilities in the U.S. will be the 2XIIB (renamed Beta II); a tandem mirror experiment caled TMX; and the Mirror Fusion Test Facility (MFTF) scheduled to be completed in 1981 at a cost of $94 million. As a background for discussing this program and mirror reactor concepts in later lectures, the current status of mirror physics will be reviewed by comparing theory and experimental data in four critical areas. These are adiabatic confinement of individual ions, electron heat losses out of the ends of the machine, the achievement of beta values of order unity; and stabilization of ''loss cone'' modes

Diode array pumped, non-linear mirror Q-switched and mode-locked

Indian Academy of Sciences (India)

A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while ...

Multiple-mirror plasma confinement

International Nuclear Information System (INIS)

Lichtenberg, A.J.; Lieberman, M.A.; Logan, B.G.

1975-01-01

A large enhancement of the confinement time can be achieved in a straight system of multiple mirrors over an equal length uniform magnetic field. The scaling is diffusive rather than that of flow, thereby scaling the square of the system length rather than linear with system length. Probably the most economic mode of operation for a reactor occurs when lambda/M is approximately l/sub c/, where lambda is the mean free path, M the mirror ratio, and l/sub c/ the length between mirrors; but where the scale length of the mirror field l/sub m/ is much less than lambda. The axial confinement time has been calculated theoretically and numerically for all important parameter regimes, and confirmed experimentally. A typical reactor calculation gives Q/sub E/ = 2 for a 400 meter system with 3000 MW(e) output. The main concern of a multiple-mirror system is stability. Linked quadrupoles can achieve average minimum-B stabilization of flute modes, and experiments have demonstrated this stabilization. Localized instabilities at finite β and enhanced diffusion resulting from the distorted flux surfaces and possibly from turbulent higher order modes still remain to be investigated

Plasma injection from the independent SHF-source in the open configuration 2. Magnetic fields of magnetic mirror configurations

International Nuclear Information System (INIS)

Beriya, Z.R.; Gogashvili, G.E.; Nanobashvili, S.I.

1992-01-01

The investigation was aimed at studying the characteristics and properties of plasma injected from independent stationary SHF source into an open magnetic trap of mirror geometry within a wide range of change in the experimental conditions. The investigations were primarily based on measurements of the distribution of charged particles in a plasma along the trap and on the dependence of the concentration on plasma production conditions in a SHF source. It is shown that the aggregate of the experimental data enables a conclusion that independent of SHF plasma can be succesfully used for filling on open magnetic trap of mirror configuration with plasma

Reversed-field multiple mirror concept

International Nuclear Information System (INIS)

Steinhauer, L.C.; Grossmann, W.; Seyler, C.E.

1978-01-01

The reversed-field multiple mirror (RFMM), is a promising technique for end-stoppering linear magnetic fusion plasmas. By this means the physics and engineering advantages of a linear plasma are gained while circumventing the endloss problem, allowing the projection of very short (less than or equal to 100 m) conceptual reactors. RFMM end-stoppering is accomplished by a string of closed field-line cells on the plasma column axis; these cells strongly retard the axial flow of particles and energy. We describe the reactor implications of the RFMM

Plasma confinement apparatus using solenoidal and mirror coils

Science.gov (United States)

Fowler, T. Kenneth; Condit, William C.

1979-01-01

A plasma confinement apparatus, wherein multiple magnetic mirror cells are linked by magnetic field lines inside of a solenoid with the mirroring regions for adjacent magnetic mirror cells each formed by a separate mirror coil inside of the solenoid. The magnetic mirror cells may be field reversed.

Ion optics of a high resolution multipassage mass spectrometer with electrostatic ion mirrors

Energy Technology Data Exchange (ETDEWEB)

Sakurai, T [Osaka Univ. (Japan). Dept. of Physics; Baril, M [Departement de Physique, Faculte des Sciences et de Genie, Universite Laval, Ste-Foy, Quebec G1K 7P4 (Canada)

1995-09-01

Ion trajectories in an electrostatic ion mirror are calculated. The interferences of the extended fringing fields of the mirror with finite aperture are studied. The results of the calculations are represented by three transfer matrices, which describe ion trajectories under the effects of a fringing field at the entrances, of an idealized mirror region, and of a fringing field at the exit. The focusing effects and ion-optical properties of mass spectrometers with electrostatic ion mirrors can be evaluated by using these transfer matrices. A high performance multipassage mass spectrometer is designed. The system has one magnet and four electrostatic sector analyzers and two ion mirrors. The double focusing condition and stigmatic focusing condition are achieved in any passage of the system. The mass resolution increases linearly with the number of passages in a magnet. (orig.).

Plasma confinement apparatus using solenoidal and mirror coils

International Nuclear Information System (INIS)

Fowler, T.K.; Condit, W.C.

1979-01-01

A plasma confinement apparatus is described, wherein multiple magnetic mirror cells are linked by magnetic field lines inside of a solenoid with the mirroring regions for adjacent magnetic mirror cells each formed by a separate mirror coil inside of the solenoid. The magnetic mirror cells may be field reversed

Plasma potential in a magnetic mirror with electron-cyclotron-resonance heating

International Nuclear Information System (INIS)

Smith, P.K.

1983-01-01

Experimental and theoretical studies of the ECRH plasma in the University of Wisconsin DE Machine magnetic mirror have been undertaken. Typical plasma parameters in these experiments were T/sub e/ - 10 to 30 eV, T/sub i/ - 4 eV, V/sub po/ (plasma potential at midplane) - 20 to 50 V, midplane plasma density n 0 - 10 16 m - 3 , B 0 (magnetic field strength on axis at midplane) - .005 to .01 T, mirror ratio R - 5 to 20. The principal experimental findings were the appearance of strong density peaks (approx. 2 x background) and notable V/sub f/ dips (approx. kT/sub e//e) in a narrow (approx. 1 cm) region near the axial positions of cyclotron resonance. The properties of these dips do not change greatly over the range of operating parameters, but are narrower at higher pressures

Nuclear structure and magnetic moment of the unstable 12B-12N mirror pair

International Nuclear Information System (INIS)

Zheng Yongnan; Zhou Dongmei; Yuan Daqing; Zuo Yi; Fan Ping; Xu Yongjun; Zhu Jiazheng; Wang Zhiqiang; Luo Hailong; Zhang Xizhen; Zhu Shengyun; Mihara, M.; Matsuta, K.; Fukuda, M.; Minamisono, T.; Suzuki, T.

2010-01-01

Magnetic moments of the A=12 unstable mirror pair nuclides 12 B and 12 N have been measured by the β-NMR technique. The experimentally measured magnetic moments are μ( 12 B)=1.00(17)μ N and μ( 12 N)=0.4571(1)μ N . The improved shell model using an SFO Hamiltonian with enhanced spin-isospin monopole proton-neutron interaction and modified single-particle energies is employed to calculate the magnetic moments of 12 B and 12 N. The calculation yields μ( 12 B)=0.929μ N and μ( 12 N)=0.452μ N and has produced a new magic number 6 for the short-lived unstable mirror pair nuclides 12 B and 12 N. (authors)

Magnetic shielding for coreless linear permanent magnet motors

NARCIS (Netherlands)

Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.

2013-01-01

This paper concerns the local reduction of the magnetic flux density by means of magnetic shielding. Using a spatial frequency description, a 2-D semi-analytical periodic model is obtained for a coreless single-sided linear permanent magnet motor. The magnetic shield is included in the modeling

Laser-start-up system for magnetic mirror fusion

International Nuclear Information System (INIS)

Frank, A.M.; Thomas, S.R.; Denhoy, B.S.; Chargin, A.K.

1976-01-01

A CO 2 laser system has been developed at LLL to provide hot start-up plasmas for magnetic mirror fusion experiments. A frozen ammonia pellet is irradiated with a laser power density in excess of 10 13 W/cm 2 in a 50-ns pulse. This system uses commercially available laser systems. Optical components were fabricated both by direct machining and standard techniques. The technologies used in this system are directly applicable to reactor scale systems

On MHD waves, fire-hose and mirror instabilities in anisotropic plasmas

Directory of Open Access Journals (Sweden)

L.-N. Hau

2007-09-01

Full Text Available Temperature or pressure anisotropies are characteristic of space plasmas, standard magnetohydrodynamic (MHD model for describing large-scale plasma phenomena however usually assumes isotropic pressure. In this paper we examine the characteristics of MHD waves, fire-hose and mirror instabilities in anisotropic homogeneous magnetized plasmas. The model equations are a set of gyrotropic MHD equations closed by the generalized Chew-Goldberger-Low (CGL laws with two polytropic exponents representing various thermodynamic conditions. Both ions and electrons are allowed to have separate plasma beta, pressure anisotropy and energy equations. The properties of linear MHD waves and instability criteria are examined and numerical examples for the nonlinear evolutions of slow waves, fire-hose and mirror instabilities are shown. One significant result is that slow waves may develop not only mirror instability but also a new type of compressible fire-hose instability. Their corresponding nonlinear structures thus may exhibit anticorrelated density and magnetic field perturbations, a property used for identifying slow and mirror mode structures in the space plasma environment. The conditions for nonlinear saturation of both fire-hose and mirror instabilities are examined.

Tandem mirror and field-reversed mirror experiments

Energy Technology Data Exchange (ETDEWEB)

Coensgen, F.H.; Simonen, T.C.; Turner, W.C.

1979-08-21

This paper is largely devoted to tandem mirror and field-reversed mirror experiments at the Lawrence Livermore Laboratory (LLL), and briefly summarizes results of experiments in which field-reversal has been achieved. In the tandem experiment, high-energy, high-density plasmas (nearly identical to 2XIIB plasmas) are located at each end of a solenoid where plasma ions are electrostatically confined by the high positive poentials arising in the end plug plasma. End plug ions are magnetically confined, and electrons are electrostatically confined by the overall positive potential of the system. The field-reversed mirror reactor consists of several small field-reversed mirror plasmas linked together for economic reasons. In the LLL Beta II experiment, generation of a field-reversed plasma ring will be investigated using a high-energy plasma gun with a transverse radial magnetic field. This plasma will be further heated and sustained by injection of intense, high-energy neutral beams.

Enhanced accuracy in novel mirror drawing after repetitive transcranial magnetic stimulation-induced proprioceptive deafferentation

DEFF Research Database (Denmark)

Balslev, Daniela; Christensen, Lars O.D.; Lee, Ji-hang

2004-01-01

a performance benefit. In this study, we tested whether deafferentation induced by repetitive transcranial magnetic stimulation (rTMS) can improve mirror tracing skills in normal subjects. Hand trajectory error during novel mirror drawing was compared across two groups of subjects that received either 1 Hz r......TMS over the somatosensory cortex contralateral to the hand or sham stimulation. Mirror tracing was more accurate after rTMS than after sham stimulation. Using a position-matching task, we confirmed that rTMS reduced proprioceptive acuity and that this reduction was largest when the coil was placed...

Feasibility Studies of Alpha-Channeling in Mirror Machines

International Nuclear Information System (INIS)

Zhmoginov, A.I.; Fisch, N.J.

2010-01-01

The linear magnetic trap is an attractive concept both for fusion reactors and for other plasma applications due to its relative engineering simplicity and high-beta operation. Applying the α-channeling technique to linear traps, such as mirror machines, can benefit this concept by efficiently redirecting α particle energy to fuel ion heating or by otherwise sustaining plasma confinement, thus increasing the effective fusion reactivity. To identify waves suitable for α-channeling a rough optimization of the energy extraction rate with respect to the wave parameters is performed. After the optimal regime is identified, a systematic search for modes with similar parameters in mirror plasmas is performed, assuming quasi-longitudinal or quasi-transverse wave propagation. Several modes suitable for α particle energy extraction are identified for both reactor designs and for proof- of-principle experiments.

Low-redundancy linear arrays in mirrored interferometric aperture synthesis.

Science.gov (United States)

Zhu, Dong; Hu, Fei; Wu, Liang; Li, Jun; Lang, Liang

2016-01-15

Mirrored interferometric aperture synthesis (MIAS) is a novel interferometry that can improve spatial resolution compared with that of conventional IAS. In one-dimensional (1-D) MIAS, antenna array with low redundancy has the potential to achieve a high spatial resolution. This Letter presents a technique for the direct construction of low-redundancy linear arrays (LRLAs) in MIAS and derives two regular analytical patterns that can yield various LRLAs in short computation time. Moreover, for a better estimation of the observed scene, a bi-measurement method is proposed to handle the rank defect associated with the transmatrix of those LRLAs. The results of imaging simulation demonstrate the effectiveness of the proposed method.

Gasdynamic Mirror Fusion Propulsion Experiment

Science.gov (United States)

Emrich, Bill; Rodgers, Stephen L. (Technical Monitor)

2000-01-01

A gasdynamic mirror (GDM) fusion propulsion experiment is currently being constructed at the NASA Marshall Space Flight Center (MSFC) to test the feasibility of this particular type of fusion device. Because of the open magnetic field line configuration of mirror fusion devices, they are particularly well suited for propulsion system applications since they allow for the easy ejection of thrust producing plasma. Currently, the MSFC GDM is constructed in three segments. The vacuum chamber mirror segment, the plasma injector mirror segment, and the main plasma chamber segment. Enough magnets are currently available to construct up to three main plasma chamber segments. The mirror segments are also segmented such that they can be expanded to accommodate new end plugging strategies with out requiring the disassembly of the entire mirror segment. The plasma for the experiment is generated in a microwave cavity located between the main magnets and the mirror magnets. Ion heating is accomplished through ambipolar diffusion. The objective of the experiment is to investigate the stability characteristics of the gasdynamic mirror and to map a region of parameter space within which the plasma can be confined in a stable steady state configuration. The mirror ratio, plasma density, and plasma "b" will be varied over a range of values and measurements subsequently taken to determine the degree of plasma stability.

A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range

Directory of Open Access Journals (Sweden)

Wei Wang

2016-09-01

Full Text Available A Fourier transform spectrometer (FTS that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, the MEMS mirror with a footprint of 4.3 mm × 3.1 mm is based on a modified lateral-shift-free (LSF bimorph actuator design with large piston and reduced tilting. Combined with a position-sensitive device (PSD for tilt angle sensing, the feedback controlled MEMS mirror generates a 430 µm stable linear piston scan with the mirror plate tilting angle less than ±0.002°. The usable piston scan range is increased to 78% of the MEMS mirror’s full scan capability, and a spectral resolution of 0.55 nm at 531.9 nm wavelength, has been achieved. It is a significant improvement compared to the prior work.

Mirror Fusion Test Facility: an intermediate device to a mirror fusion reactor

International Nuclear Information System (INIS)

Karpenko, V.N.

1983-01-01

The Mirror Fusion Test Facility (MFTF-B) now under construction at Lawrence Livermore National Laboratory represents more than an order-of-magnitude step from earlier magnetic-mirror experiments toward a future mirror fusion reactor. In fact, when the device begins operating in 1986, the Lawson criteria of ntau = 10 14 cm -3 .s will almost be achieved for D-T equivalent operation, thus signifying scientific breakeven. Major steps have been taken to develop MFTF-B technologies for tandem mirrors. Steady-state, high-field, superconducting magnets at reactor-revelant scales are used in the machine. The 30-s beam pulses, ECRH, and ICRH will also introduce steady-state technologies in those systems

Design and fabrication of the superconducting-magnet system for the Mirror Fusion Test Facility (MFTF-B)

International Nuclear Information System (INIS)

Tatro, R.E.; Wohlwend, J.W.; Kozman, T.A.

1982-01-01

The superconducting magnet system for the Mirror Fusion Test Facility (MFTF-B) consists of 24 magnets; i.e. two pairs of C-shaped Yin-Yang coils, four C-shaped transition coils, four solenoidal axicell coils, and a 12-solenoid central cell. General Dynamics Convair Division has designed all the coils and is responsible for fabricating 20 coils. The two Yin-Yang pairs (four coils) are being fabricated by the Lawrence Livermore National Laboratory. Since MFTF-B is not a magnet development program, but rather a major physics experiment critical to the mirror fusion program, the basic philosophy has been to use proven materials and analytical techniques wherever possible. The transition and axicell coils are currently being analyzed and designed, while fabrication is under way on the solenoid magnets

Mechanical behavior of the mirror fusion test Facility superconducting magnet coils

International Nuclear Information System (INIS)

Horvath, J.A.

1980-01-01

The mechanical response to winding and electromagnetic loads of the Mirror Fusion Test Facility (MFTF) superconducting coil pack is presented. The 375-ton (3300 N) MFTF Yin-Yang magnet, presently the world's largest superconducting magnet, is scheduled for acceptance cold-testing in May of 1981. The assembly is made up of two identical coils which together contain over 15 miles (24 km) of superconductor wound in 58 consecutive layers of 24 turns each. Topics associated with mechanical behavior include physical properties of the coil pack and its components, winding pre-load effects, finite element analysis, magnetic load redistribution, and the design impact of predicted conductor motion

Vent rate of superconducting magnets during quench in the Mirror Fusion Test Facility

International Nuclear Information System (INIS)

Slack, D.S.

1979-01-01

When a superconducting magnet goes normal, resistive heating in the conductor evaporates surrounding LHe, which must be vented. The nature and speed at which the magnet goes normal and He is vented are not subject to rigorous analysis. This paper presents vent data from an existing magnet. An approximate mathematical model is derived and fitted to the data to permit scaling of vent requirements to larger size magnets. The worst case models of the vent employed in Mirror Fusion Test Facility (MFTF) cryogenic system design are also presented

Mirror profile optimization for nano-focusing KB mirror

International Nuclear Information System (INIS)

Zhang Lin; Baker, Robert; Barrett, Ray; Cloetens, Peter; Dabin, Yves

2010-01-01

A KB focusing mirror width profile has been optimized to achieve nano-focusing for the nano-imaging end-station ID22NI at the ESRF. The complete mirror and flexure bender assembly has been modeled in 3D with finite element analysis using ANSYS. Bender stiffness, anticlastic effects and geometrical non-linear effects have been considered. Various points have been studied: anisotropy and crystal orientation, stress in the mirror and bender, actuator resolution and the mirror-bender adhesive bonding... Extremely high performance of the mirror is expected with residual slope error smaller than 0.6 μrad, peak-to-valley, compared to the bent slope of 3000 μrad.

The magnet power control system for the tandem mirror experiment-upgrade

International Nuclear Information System (INIS)

Bell, H.H.

1983-01-01

This paper describes the desktop computer/CAMAC based system that controls the power source for the Tandem Mirror Experiment-Upgrade (TMX-U) magnet power system. Presently it contains 42 dc rectifier power supplies connected to 24 magnet coils arranged in 17 circuits. During each shot, the system delivers 22.6 MW dc to the magnets for about 3 s. The system is presently being changed to add six power supplies, two solenoidal throttle coils, and two reverse C-coils. When complete, the delivered power will increase to 36.9 MW. The closed-loop control system usually provides current (and thus, magnetic field) that is within 1% of the requested current. Achieving this accuracy required using grounding, shielding, and isolation methods to reduce noise and related problems

Physics issues in mirror and tandem mirror systems

International Nuclear Information System (INIS)

Post, R.F.

1984-01-01

Over the years the study of the confinement of high temperature plasma in magnetic mirror systems has presented researchers with many unusual physics problems. Many of these issues are by now understood theoretically and documented experimentally. With the advent of the tandem mirror idea, some new issues have emerged and are now under intensive study. These include: (1) the generation and control of ambipolar confining potentials and their effect on axial confinement and, (2) the combined influence of nonaxisymmetric magnetic fields (used to ensure MHD stability) and electric magnetic particle drifts on radial transport. Physics considerations associated with these two categories of issues will be reviewed, including concepts for the control of radial transport, under study or proposed

Characteristics of hot electron ring in a simple magnetic mirror field

International Nuclear Information System (INIS)

Hosokawa, M.; Ikegami, H.

1980-12-01

Characteristics of hot electron ring are studied in a simple magnetic mirror machine (mirror ratio 2 : 1) with a diameter of 30 cm at the midplane and with the distance of 80 cm between the mirrors. Maximum microwave input power is 5 kW at 6.4 GHz with the corresponding power density of approximately 0.3 W/cm 3 . With a background cold plasma of 4 x 10 11 cm -3 , hot electron rings are most effectively generated in two cases when the magnetic field on the axis of the midplane is set near the fundamental or the second harmonic electron cyclotron resonance to the applied microwave frequency. Density profile of the hot electrons is observed to take a so-called ring shape with a radius controllable by the magnetic field intensity and with an axial length of approximately 10 cm. The radial cut view of the ring, however, indicates an M shape density profile, and the density of the hot electrons on the axis is about one half of the density at the ring. Approximately 30 msec is needed before generating the hot electron ring at the density of 10 10 cm -3 with an average kinetic energy of 100 keV. The ultimate energy distribution function is observed to have a stepwise cut in the high energy tail and no energetic components above 1 MeV are detected. The hot electron ring is susceptible to a few instabilities which can be artificially triggered. One of the instabilities is observed to associate with a loss of lower energetic electrons and microwave bursts. At the instability, the ring shape is observed to transform into a filled cylinder in a few microseconds and disappear. (author)

Evolution of the mirror machine

International Nuclear Information System (INIS)

Damm, C.C.

1983-01-01

The history of the magnetic-mirror approach to a fusion reactor is primarily the history of our understanding and control of several crucial physics issues, coupled with progress in the technology of heating and confining a reacting plasma. The basic requirement of an MHD-stable plasma equilibrium was achieved following the early introduction of minimum-B multipolar magnetic fields. In refined form, the same magnetic-well principle carries over to our present experiments and to reactor designs. The higher frequency microinstabilities, arising from the non-Maxwellian particle distributions inherent in mirror machines, have gradually come under control as theoretical prescriptions for distribution functions have been applied in the experiments. Even with stability, the classical plasma leakage through the mirrors posed a serious question for reactor viability until the principle of electrostatic axial stoppering was applied in the tandem mirror configuration. Experiments to test this principle successfully demonstrated the substantial improvement in confinement predicted. Concurrent with advances in mirror plasma physics, development of both high-power neutral beam injectors and high-speed vacuum pumping techniques has played a crucial role in ongoing experiments. Together with superconducting magnets, cryogenic pumping, and high-power radiofrequency heating, these technologies have evolved to a level that extrapolates readily to meet the requirements of a tandem mirror fusion reactor

Review of mirror fusion reactor designs

International Nuclear Information System (INIS)

Bender, D.J.

1977-01-01

Three magnetic confinement concepts, based on the mirror principle, are described. These mirror concepts are summarized as follows: (1) fusion-fission hybrid reactor, (2) tandem mirror reactor, and (3) reversed field mirror reactor

Chiral mirrors

International Nuclear Information System (INIS)

Plum, Eric; Zheludev, Nikolay I.

2015-01-01

Mirrors are used in telescopes, microscopes, photo cameras, lasers, satellite dishes, and everywhere else, where redirection of electromagnetic radiation is required making them arguably the most important optical component. While conventional isotropic mirrors will reflect linear polarizations without change, the handedness of circularly polarized waves is reversed upon reflection. Here, we demonstrate a type of mirror reflecting one circular polarization without changing its handedness, while absorbing the other. The polarization-preserving mirror consists of a planar metasurface with a subwavelength pattern that cannot be superimposed with its mirror image without being lifted out of its plane, and a conventional mirror spaced by a fraction of the wavelength from the metasurface. Such mirrors enable circularly polarized lasers and Fabry-Pérot cavities with enhanced tunability, gyroscopic applications, polarization-sensitive detectors of electromagnetic waves, and can be used to enhance spectroscopies of chiral media

The strange physics of low frequency mirror mode turbulence in the high temperature plasma of the magnetosheath

Directory of Open Access Journals (Sweden)

R. A. Treumann

2004-01-01

Full Text Available Mirror mode turbulence is the lowest frequency perpendicular magnetic excitation in magnetized plasma proposed already about half a century ago by Rudakov and Sagdeev (1958 and Chandrasekhar et al. (1958 from fluid theory. Its experimental verification required a relatively long time. It was early recognized that mirror modes for being excited require a transverse pressure (or temperature anisotropy. In principle mirror modes are some version of slow mode waves. Fluid theory, however, does not give a correct physical picture of the mirror mode. The linear infinitesimally small amplitude physics is described correctly only by including the full kinetic theory and is modified by existing spatial gradients of the plasma parameters which attribute a small finite frequency to the mode. In addition, the mode is propagating only very slowly in plasma such that convective transport is the main cause of flow in it. As the lowest frequency mode it can be expected that mirror modes serve as one of the dominant energy inputs into plasma. This is however true only when the mode grows to large amplitude leaving the linear stage. At such low frequencies, on the other hand, quasilinear theory does not apply as a valid saturation mechanism. Probably the dominant processes are related to the generation of gradients in the plasma which serve as the cause of drift modes thus transferring energy to shorter wavelength propagating waves of higher nonzero frequency. This kind of theory has not yet been developed as it has not yet been understood why mirror modes in spite of their slow growth rate usually are of very large amplitudes indeed of the order of |B/B0|2~O(1. It is thus highly reasonable to assume that mirror modes are instrumental for the development of stationary turbulence in high temperature plasma. Moreover, since the magnetic field in mirror turbulence forms extended though slightly oblique magnetic bottles, low parallel energy particles can be trapped

Cluster magnetic field observations in the magnetosheath: four-point measurements of mirror structures

Directory of Open Access Journals (Sweden)

E. A. Lucek

2001-09-01

Full Text Available The Cluster spacecraft have returned the first simultaneous four-point measurements of the magnetosheath. We present an analysis of data recorded on 10 November 2000, when the four spacecrafts observed an interval of strong mirrorlike activity. Correlation analysis between spacecraft pairs is used to examine the scale size of the mirror structures in three dimensions. Two examples are presented which suggest that the scale size of mirror structures is ~ 1500–3000 km along the flow direction, and shortest along the magnetopause normal (< 600 km, which, in this case, is approximately perpendicular to both the mean magnetic field and the magnetosheath flow vector. Variations on scales of ~ 750–1000 km are found along the maximum variance direction. The level of correlation in this direction, however, and the time lag observed, are found to be variable. These first results suggest that variations occur on scales of the order of the spacecraft separation ( ~ 1000 km in at least two directions, but analysis of further examples and a statistical survey of structures observed with different magnetic field orientations and tetrahedral configurations will enable us to describe more fully the size and orientation of mirror structures.Key words. Magnetosphenic physics (magnetosheath; plasma waves and instabilities

Cluster magnetic field observations in the magnetosheath: four-point measurements of mirror structures

Directory of Open Access Journals (Sweden)

E. A. Lucek

Full Text Available The Cluster spacecraft have returned the first simultaneous four-point measurements of the magnetosheath. We present an analysis of data recorded on 10 November 2000, when the four spacecrafts observed an interval of strong mirrorlike activity. Correlation analysis between spacecraft pairs is used to examine the scale size of the mirror structures in three dimensions. Two examples are presented which suggest that the scale size of mirror structures is ~ 1500–3000 km along the flow direction, and shortest along the magnetopause normal (< 600 km, which, in this case, is approximately perpendicular to both the mean magnetic field and the magnetosheath flow vector. Variations on scales of ~ 750–1000 km are found along the maximum variance direction. The level of correlation in this direction, however, and the time lag observed, are found to be variable. These first results suggest that variations occur on scales of the order of the spacecraft separation ( ~ 1000 km in at least two directions, but analysis of further examples and a statistical survey of structures observed with different magnetic field orientations and tetrahedral configurations will enable us to describe more fully the size and orientation of mirror structures.

Key words. Magnetosphenic physics (magnetosheath; plasma waves and instabilities

Helically linked mirror arrangement

International Nuclear Information System (INIS)

Ranjan, P.

1986-08-01

A scheme is described for helical linking of mirror sections, which endeavors to combine the better features of toroidal and mirror devices by eliminating the longitudinal loss of mirror machines, having moderately high average β and steady state operation. This scheme is aimed at a device, with closed magnetic surfaces having rotational transform for equilibrium, one or more axisymmetric straight sections for reduced radial loss, a simple geometrical axis for the links and an overall positive magnetic well depth for stability. We start by describing several other attempts at linking of mirror sections, made both in the past and the present. Then a description of our helically linked mirror scheme is given. This example has three identical straight sections connected by three sections having helical geometric axes. A theoretical analysis of the magnetic field and single-particle orbits in them leads to the conclusion that most of the passing particles would be confined in the device and they would have orbits independent of pitch angle under certain conditions. Numerical results are presented, which agree well with the theoretical results as far as passing particle orbits are concerned

Construction and testing of the Mirror Fusion Test Facility magnets

International Nuclear Information System (INIS)

Kozman, T.; Shimer, D.; VanSant, J.; Zbasnik, J.

1986-08-01

This paper describes the construction and testing of the Mirror Fusion Test Facility superconducting magnet set. Construction of the first Yin Yang magnet was started in 1978. And although this particular magnet was later modified, the final construction of these magnets was not completed until 1985. When completed these 42 magnets weighed over 1200 tonnes and had a maximum stored energy of approximately 1200 MJ at full field. Together with power supplies, controls and liquid nitrogen radiation shields the cost of the fabrication of this system was over $100M. General Dynamics/Convair Division was responsible for the system design and the fabrication of 20 of the magnets. This contract was the largest single procurement action at the Lawrence Livermore National Laboratory. During the PACE acceptance tests, the 26 major magnets were operated at full field for more than 24 hours while other MFTF subsystems were tested. From all of the data, the magnets operated to the performance specifications. For physics operation in the future, additional helium and nitrogen leak checking and repair will be necessary. In this report we will discuss the operation and testing of the MFTF Magnet System, the world's largest superconducting magnet set built to date. The topics covered include a schedule of the major events, summary of the fabrication work, summary of the installation work, summary of testing and test results, and lessons learned

Magnetic Diagnostics on the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Hutchinson, T. M.; Weber, T. E.; Boguski, J. C.; Intrator, T. P.; Smith, R. J.; Dunn, J. P.

2013-10-01

The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory was built to investigate the physics of high-Alfvénic, supercritical, magnetized shocks through the acceleration and subsequent stagnation of a Field Reversed Configuration (FRC) plasmoid against a magnetic mirror and/or plasma target. An array of high-bandwidth, multi-axis, robust, internal magnetic probes has been constructed to characterize flux compression ratios, instability formation, and turbulent macro-scale features of the post-shock plasma. The mirror magnet is mounted on a linear translation stage, providing a capability to axially move the shock layer through the probe field of view. An independent, external probe array also provides conventional information on the FRC shape, velocity, and total pressure during the formation and acceleration phases. Probe design, characterization, configuration, and initial results are presented. This work is supported by the DOE OFES and NNSA under LANS contract DE-AC52-06NA25369. LA-UR-13-25189.

Overview of NASA Magnet and Linear Alternator Research Efforts

Science.gov (United States)

Geng, Steven M.; Niedra, Janis M.; Schwarze, Gene E.

2005-02-01

The Department of Energy, Lockheed Martin, Stirling Technology Company, and NASA Glenn Research Center are developing a high-efficiency, 110 watt Stirling Radioisotope Generator (SRG110) for NASA Space Science missions. NASA Glenn is conducting in-house research on rare earth permanent magnets and on linear alternators to assist in developing a free-piston Stirling convertor for the SRG110 and for developing advanced technology. The permanent magnet research efforts include magnet characterization, short-term magnet aging tests, and long-term magnet aging tests. Linear alternator research efforts have begun just recently at GRC with the characterization of a moving iron type linear alternator using GRC's alternator test rig. This paper reports on the progress and future plans of GRC's magnet and linear alternator research efforts.

Connection between adiabaticity and the mirror mode

International Nuclear Information System (INIS)

Cohen, R.H.

1976-01-01

The size of magnetic moment jumps of a particle in a long, thin equilibrium magnetic mirror field is shown to be related to the complex zeroes of the mirror mode parameter B + 4πdP/sub perpendicular//dB. A consequence is that adiabaticity places a lower limit on β than does the mirror mode

Physics of mirror systems

International Nuclear Information System (INIS)

Post, R.F.

1982-05-01

In recent years the emphasis in research on the magnetic mirror approach to fusion has been shifted to address what are essentially economically-motivated issues. The introduction of the Tandem Mirror idea solved in principal the problem of low Q (low fusion power gain) of mirror-based fusion systems. In order to optimize the tandem mirror idea from an economic standpoint, some important improvements have been suggested. These improvements include the thermal barrier idea of Baldwin and Logan and the axicell concept of Kesner. These new modifications introduce some special physics considerations. Among these are (1) The MHD stability properties of high energy electron components in the end cells; (2) The optimization of end-cell magnetic field configurations with the objective of minimizing equilibrium parallel currents; (3) The suppression of microstabilities by use of sloshing ion distributions. Following a brief outline of tandem mirror concepts, the above three topics are discussed, with illustrative examples taken from earlier work or from recent design studies

Mirror fusion--fission hybrids

International Nuclear Information System (INIS)

Lee, J.D.

1978-01-01

The fusion-fission concept and the mirror fusion-fission hybrid program are outlined. Magnetic mirror fusion drivers and blankets for hybrid reactors are discussed. Results of system analyses are presented and a reference design is described

Is the human mirror neuron system plastic? Evidence from a transcranial magnetic stimulation study.

Science.gov (United States)

Mehta, Urvakhsh Meherwan; Waghmare, Avinash V; Thirthalli, Jagadisha; Venkatasubramanian, Ganesan; Gangadhar, Bangalore N

2015-10-01

Virtual lesions in the mirror neuron network using inhibitory low-frequency (1Hz) transcranial magnetic stimulation (TMS) have been employed to understand its spatio-functional properties. However, no studies have examined the influence of neuro-enhancement by using excitatory high-frequency (20Hz) repetitive transcranial magnetic stimulation (HF-rTMS) on these networks. We used three forms of TMS stimulation (HF-rTMS, single and paired pulse) to investigate whether the mirror neuron system facilitates the motor system during goal-directed action observation relative to inanimate motion (motor resonance), a marker of putative mirror neuron activity. 31 healthy individuals were randomized to receive single-sessions of true or sham HF-rTMS delivered to the left inferior frontal gyrus - a component of the human mirror system. Motor resonance was assessed before and after HF-rTMS using three TMS cortical reactivity paradigms: (a) 120% of resting motor threshold (RMT), (b) stimulus intensity set to evoke motor evoked potential of 1-millivolt amplitude (SI1mV) and (c) a short latency paired pulse paradigm. Two-way RMANOVA showed a significant group (true versus sham) X occasion (pre- and post-HF-rTMS motor resonance) interaction effect for SI1mV [F(df)=6.26 (1, 29), p=0.018] and 120% RMT stimuli [F(df)=7.01 (1, 29), p=0.013] indicating greater enhancement of motor resonance in the true HF-rTMS group than the sham-group. This suggests that HF-rTMS could adaptively modulate properties of the mirror neuron system. This neuro-enhancement effect is a preliminary step that can open translational avenues for novel brain stimulation therapeutics targeting social-cognition deficits in schizophrenia and autism. Copyright © 2015 Elsevier B.V. All rights reserved.

Survey of mirror machine reactors

International Nuclear Information System (INIS)

Condit, W.C.

1978-01-01

The Magnetic Mirror Fusion Program is one of the two main-line fusion efforts in the United States. Starting from the simple axisymmetric mirror concept in the 1950's, the program has successfully overcome gross flute-type instabilities (using minimum-B magnetic fields), and the most serious of the micro-instabilities which plagued it (the drift-cyclotron loss-cone mode). Dense plasmas approaching the temperature range of interest for fusion have been created (n/sub p/ = 10 14 /cc at 10 to 12 keV). At the same time, rather extensive conceptual design studies of possible mirror configurations have led to three principle designs of interest: the standard mirror fission-fusion hybrid, tandem mirror, and the field-reversed mirror. The lectures will discuss these three concepts in turn. There will be no discussion of diagnostics for the mirror machine in these lectures, but typical plasma parameters will be given for each type of machine, and the diagnostic requirements will be apparent. In a working fusion reactor, diagnostics will be required for operational control, and remarks will be made on this subject

The neuronal correlates of mirror illusion in children with spastic hemiparesis: a study with functional magnetic resonance imaging.

Science.gov (United States)

Weisstanner, Christian; Saxer, Stefanie; Wiest, Roland; Kaelin-Lang, Alain; Newman, Christopher J; Steinlin, Maja; Grunt, Sebastian

2017-03-21

To investigate the neuronal activation pattern underlying the effects of mirror illusion in children/adolescents with normal motor development and in children/adolescents with hemiparesis and preserved contralateral corticospinal organisation. The type of cortical reorganisation was classified according to results of transcranial magnetic stimulation. Only subjects with congenital lesions and physiological contralateral cortical reorganisation were included. Functional magnetic resonance imaging was performed to investigate neuronal activation patterns with and without a mirror box. Each test consisted of a unimanual and a bimanual motor task. Seven children/adolescents with congenital hemiparesis (10-20 years old, three boys and four girls) and seven healthy subjects (8-17 years old, four boys and three girls) participated in this study. In the bimanual experiment, children with hemiparesis showed a significant effect of the mirror illusion (phemiparesis leads to activation of brain areas involved in visual conflict detection and cognitive control to resolve this conflict. This effect is observed only in bimanual training. We consider that for mirror therapy in children and adolescents with hemiparesis a bimanual approach is more suitable than a unimanual approach.

Design and experimental validation of Unilateral Linear Halbach magnet arrays for single-sided magnetic resonance.

Science.gov (United States)

Bashyam, Ashvin; Li, Matthew; Cima, Michael J

2018-07-01

Single-sided NMR has the potential for broad utility and has found applications in healthcare, materials analysis, food quality assurance, and the oil and gas industry. These sensors require a remote, strong, uniform magnetic field to perform high sensitivity measurements. We demonstrate a new permanent magnet geometry, the Unilateral Linear Halbach, that combines design principles from "sweet-spot" and linear Halbach magnets to achieve this goal through more efficient use of magnetic flux. We perform sensitivity analysis using numerical simulations to produce a framework for Unilateral Linear Halbach design and assess tradeoffs between design parameters. Additionally, the use of hundreds of small, discrete magnets within the assembly allows for a tunable design, improved robustness to variability in magnetization strength, and increased safety during construction. Experimental validation using a prototype magnet shows close agreement with the simulated magnetic field. The Unilateral Linear Halbach magnet increases the sensitivity, portability, and versatility of single-sided NMR. Copyright © 2018 Elsevier Inc. All rights reserved.

MAGNETIC INDUCTION DISTRIBUTION IN A LINEAR SYNCHRONUS MOTOR WITH MAGNETIC SUSPENSION

Directory of Open Access Journals (Sweden)

D.I. Parkhomenko

2013-02-01

Full Text Available Results of computer simulation and experimental investigations of magnetic induction distribution in a coaxial linear synchronous motor with magnetic suspension are presented. The magnetic induction distribution has been studied both in the motor air gap and on the runner surface.

Critical energy in the cyclotron heating of ions in a mirror machine

International Nuclear Information System (INIS)

Gutierrez T, C.; Hernandez A, O.

2002-01-01

The problem of heating in the plasma sources where the geometry of the magnetic field forms a magnetic mirror as it is the case of the Ecr sources type, for maintaining the reload, it continues being an actual important problem. There are two methods for the analysis of this problem. The first of these methods is the stochastic mechanism of a particle where it is considered the existence of three characteristic frequencies as the cyclotron frequency, the electromagnetic field frequency and the transit frequency. The second method is that related with the non linear interaction of waves where the collective effects of the particles are the most important. In this work, in the Hamiltonian formalism, the stochastic mechanism in the cyclotron heating is analysed. It is considered the particular case of a plasma source with an external magnetic field, type mirror where a TE 11 electromagnetic wave is injected. The critical energy in the resonance mixing is calculated by the Poincare mapping method. The heterogeneity of the magnetic field is analysed. (Author)

Modelling a linear PM motor including magnetic saturation

NARCIS (Netherlands)

Polinder, H.; Slootweg, J.G.; Compter, J.C.; Hoeijmakers, M.J.

2002-01-01

The use of linear permanent-magnet (PM) actuators increases in a wide variety of applications because of the high force density, robustness and accuracy. The paper describes the modelling of a linear PM motor applied in, for example, wafer steppers, including magnetic saturation. This is important

Injection, compression and confinement of electrons in a magnetic mirror

International Nuclear Information System (INIS)

Fisher, A.

1975-01-01

A Helmholtz coil configuration has been constructed where the magnetic field can be increased to about 10 kGauss in 20 μsec. Electrons are injected from a hot tantalum filament between two plates across which a potential of about 5 keV is applied. The electric field E is perpendicular to the magnetic field B so that the direction of the E x B drift is radial--into the magnetic mirror. About 10 14 electrons were injected and about 10 13 electrons were trapped. The initial electron energy was about 5 keV and after compression 500 keV x-rays were observed. The confinement time is very sensitive to vacuum. Confinement times of milliseconds and good compression were observed at vacuum of 5.10 -5 torr or less. Above 5.10 -5 torr there was no trapping or compression. After a compressed ring of electrons was formed, it was released by a pulse applied to one of the Helmholtz coils that reduced the field. Ejection of the electron ring was observed by x-ray measurements

Magnets for the Mirror Fusion Test Facility: testing of the first Yin-Yang and the design and development of other magnets

International Nuclear Information System (INIS)

Kozman, T.A.; Wang, S.T.; Chang, Y.

1983-01-01

Completed in May 1981, the first Yin-Yang magnet for the tandem Mirror Fusion Test Facility (MFTF-B) at Lawrence Livermore National Laboratory (LLNL) was successfully tested in February 1982 to its full design field (7.68 T) and current (5775 A). Since that time, the entire magnet array has been reconfigured - from the original A-cell to an axicell design. The MFTF-B magnet array now contains a total of 26 large superconducting coils: 2 sets of yin-yang pairs, 2 sets of transition magnets (each containing two coils), 2 sets of axicell magnets (each containing three coils), and 12 central-cell solenoids. This paper chronicles recent magnet history - from te testing of the initial yin-yang set, through the design of the axicell configuration, to the planned development of the system

Broad-band linear polarization and magnetic intensification in rotating magnetic stars

International Nuclear Information System (INIS)

Degl'Innocenti, M.L.; Calamai, G.; Degl'Innocenti, E.L.; Patriarchi, P.

1981-01-01

Magnetic intensification is proposed as a mechanism to explain the general features of the variable broad-band linear polarization emerging from rotating magnetic stars. This mechanism is studied in detail, and some efforts are made to investigate the wide variety of polarization diagrams that can result from it. Theoretical results are compared with direct observations of the variable magnetic star 53 Cam to determine its geometric and magnetic configuration

A linear magnetic motor and generator

Science.gov (United States)

Studer, P. A.

1980-01-01

In linear magnetic motor and generator suitable for remote and hostile environments, magnetic forces drive reciprocating shaft along its axis. Actuator shaft is located in center of cylindrical body and may be supported by either contacting or noncontacting bearings. When device operates as bidirectional motor, drive coil selectively adds and subtracts magnetic flux to and from flux paths, producing forces that drive actuator along axis. When actuator is driven by external reciprocating engine, device becomes ac generator.

Linear magnetic motor/generator. [to generate electric energy using magnetic flux for spacecraft power supply

Science.gov (United States)

Studer, P. A. (Inventor)

1982-01-01

A linear magnetic motor/generator is disclosed which uses magnetic flux to provide mechanical motion or electrical energy. The linear magnetic motor/generator includes an axially movable actuator mechanism. A permament magnet mechanism defines a first magnetic flux path which passes through a first end portion of the actuator mechanism. Another permament magnet mechanism defines a second magnetic flux path which passes through a second end portion of the actuator mechanism. A drive coil defines a third magnetic flux path passing through a third central portion of the actuator mechanism. A drive coil selectively adds magnetic flux to and subtracts magnetic flux from magnetic flux flowing in the first and second magnetic flux path.

Coil winder for the magnet of the mirror fusion test facility

International Nuclear Information System (INIS)

Ling, R.C.

1977-01-01

A coil winder was designed for the purpose of fabricating the superconducting magnets of the Mirror Fusion Test Facility. The superconducting magnets are a displaced ying-yang pair, each having major and minor radii of 2.5 and 0.75 m, respectively, and cross section of 0.42 m by about 1.03 m. The superconductor cross section is a square, 13 mm on a side, and consists of a core of niobium-titanium embedded copper and a solid copper stabilizer. Conceptual studies made at Lawrence Livermore Laboratory of the coil winder resulted in concept drawings and a procurement specification. Final design was made by the contractor, and the coil winder is now in fabrication. This paper describes the performance requirements of the winder, and the evolution of its design from conceptual stage to completion

Observation of spatial resolution of ECR plasma on the MM-2 magnetic mirror

International Nuclear Information System (INIS)

Duan Shuyun; Gu Biao; Guan Weishu; Cheng Shiqing; Liu Rong; Chen Kangwei; Shang Zhenkui

1991-04-01

The measuring method and results of the ECR plasma properties taken from hard X-ray pinhole camera on the MM-2 magnetic mirror are presented. This non-destructive imaging method can directly display the spatial distribution of hot electron plasma. A frame of clear picture could be taken at one shot of discharge. The relationships between emission intensity and discharge parameters are also shown by experimental pictures

A transcranial magnetic stimulation study of the effect of visual orientation on the putative human mirror neuron system

OpenAIRE

Burgess, Jed D.; Arnold, Sara L.; Fitzgibbon, Bernadette M.; Fitzgerald, Paul B.; Enticott, Peter G.

2013-01-01

Mirror neurons are a class of motor neuron that are active during both the performance and observation of behavior, and have been implicated in interpersonal understanding There is evidence to suggest that the mirror response is modulated by the perspective from which an action is presented (e.g., egocentric or allocentric). Most human research, however, has only examined this when presenting intransitive actions. Twenty-three healthy adult participants completed a transcranial magnetic stimu...

Ultra-long magnetization needle induced by focusing azimuthally polarized beams with a spherical mirror.

Science.gov (United States)

Hang, Li; Luo, Kai; Fu, Jian; Chang, Yizhe; Wang, Ying; Chen, Peifeng

2018-03-20

Based on extended Richards-Wolf theory for axisymmetric surfaces and the inverse Faraday effect, we propose the generation of a purely longitudinal magnetization needle by focusing Gaussian annular azimuthally polarized beams with a spherical mirror. The needle obtained has a longitudinal length varying hundreds to thousands of wavelengths while keeping the lateral size under 0.4λ, and the corresponding aspect ratio can easily reach more than 2000. It may be the first time that a magnetization needle whose aspect ratio is over 500 has been achieved. The approximate analytical expressions of the magnetization needle are given, and the longitudinal length is tunable by changing the value of the angular thickness and the position of the annular beams.

A transcranial magnetic stimulation study of the effect of visual orientation on the putative human mirror neuron system

Science.gov (United States)

Burgess, Jed D.; Arnold, Sara L.; Fitzgibbon, Bernadette M.; Fitzgerald, Paul B.; Enticott, Peter G.

2013-01-01

Mirror neurons are a class of motor neuron that are active during both the performance and observation of behavior, and have been implicated in interpersonal understanding. There is evidence to suggest that the mirror response is modulated by the perspective from which an action is presented (e.g., egocentric or allocentric). Most human research, however, has only examined this when presenting intransitive actions. Twenty-three healthy adult participants completed a transcranial magnetic stimulation experiment that assessed corticospinal excitability whilst viewing transitive hand gestures from both egocentric (i.e., self) and allocentric (i.e., other) viewpoints. Although action observation was associated with increases in corticospinal excitability (reflecting putative human mirror neuron activity), there was no effect of visual perspective. These findings are discussed in the context of contemporary theories of mirror neuron ontogeny, including models concerning associative learning and evolutionary adaptation. PMID:24137125

A transcranial magnetic stimulation study of the effect of visual orientation on the putative human mirror neuron system.

Science.gov (United States)

Burgess, Jed D; Arnold, Sara L; Fitzgibbon, Bernadette M; Fitzgerald, Paul B; Enticott, Peter G

2013-01-01

Mirror neurons are a class of motor neuron that are active during both the performance and observation of behavior, and have been implicated in interpersonal understanding. There is evidence to suggest that the mirror response is modulated by the perspective from which an action is presented (e.g., egocentric or allocentric). Most human research, however, has only examined this when presenting intransitive actions. Twenty-three healthy adult participants completed a transcranial magnetic stimulation experiment that assessed corticospinal excitability whilst viewing transitive hand gestures from both egocentric (i.e., self) and allocentric (i.e., other) viewpoints. Although action observation was associated with increases in corticospinal excitability (reflecting putative human mirror neuron activity), there was no effect of visual perspective. These findings are discussed in the context of contemporary theories of mirror neuron ontogeny, including models concerning associative learning and evolutionary adaptation.

Issues facing the U. S. mirror program

Energy Technology Data Exchange (ETDEWEB)

George, T.V.

1978-07-01

Some of the current issues associated with the U.S. Magnetic Mirror Program are analyzed. They are presented as five separate papers entitled: (1) Relevant Issues Broughtup by the Mirror Reactor Design Studies. (2) An Assessment of the Design Study of the 1 MeV Neutral Beam Injector Required for a Tandem Mirror Reactor. (3) The Significance of the Radial Plasma Size Measured in Units of Ion Gyroradii in Tandem Mirrors and Field Reversed Mirrors. (4) Producing Field Reversed Mirror Plasmas by Methods used in Field Reversed Theta Pinch. (5) RF Stoppering of Mirror Confined Plasma.

Mirror dark matter and large scale structure

International Nuclear Information System (INIS)

Ignatiev, A.Yu.; Volkas, R.R.

2003-01-01

Mirror matter is a dark matter candidate. In this paper, we reexamine the linear regime of density perturbation growth in a universe containing mirror dark matter. Taking adiabatic scale-invariant perturbations as the input, we confirm that the resulting processed power spectrum is richer than for the more familiar cases of cold, warm and hot dark matter. The new features include a maximum at a certain scale λ max , collisional damping below a smaller characteristic scale λ S ' , with oscillatory perturbations between the two. These scales are functions of the fundamental parameters of the theory. In particular, they decrease for decreasing x, the ratio of the mirror plasma temperature to that of the ordinary. For x∼0.2, the scale λ max becomes galactic. Mirror dark matter therefore leads to bottom-up large scale structure formation, similar to conventional cold dark matter, for x(less-or-similar sign)0.2. Indeed, the smaller the value of x, the closer mirror dark matter resembles standard cold dark matter during the linear regime. The differences pertain to scales smaller than λ S ' in the linear regime, and generally in the nonlinear regime because mirror dark matter is chemically complex and to some extent dissipative. Lyman-α forest data and the early reionization epoch established by WMAP may hold the key to distinguishing mirror dark matter from WIMP-style cold dark matter

Mirror fusion reactor design

International Nuclear Information System (INIS)

Neef, W.S. Jr.; Carlson, G.A.

1979-01-01

Recent conceptual reactor designs based on mirror confinement are described. Four components of mirror reactors for which materials considerations and structural mechanics analysis must play an important role in successful design are discussed. The reactor components are: (a) first-wall and thermal conversion blanket, (b) superconducting magnets and their force restraining structure, (c) neutral beam injectors, and (d) plasma direct energy converters

Fokker-Planck equation in mirror research

International Nuclear Information System (INIS)

Post, R.F.

1983-01-01

Open confinement systems based on the magnetic mirror principle depend on the maintenance of particle distributions that may deviate substantially from Maxwellian distributions. Mirror research has therefore from the beginning relied on theoretical predictions of non-equilibrium rate processes obtained from solutions to the Fokker-Planck equation. The F-P equation plays three roles: Design of experiments, creation of classical standards against which to compare experiment, and predictions concerning mirror based fusion power systems. Analytical and computational approaches to solving the F-P equation for mirror systems will be reviewed, together with results and examples that apply to specific mirror systems, such as the tandem mirror

Linearized models for a new magnetic control in MAST

International Nuclear Information System (INIS)

Artaserse, G.; Maviglia, F.; Albanese, R.; McArdle, G.J.; Pangione, L.

2013-01-01

Highlights: ► We applied linearized models for a new magnetic control on MAST tokamak. ► A suite of procedures, conceived to be machine independent, have been used. ► We carried out model-based simulations, taking into account eddy currents effects. ► Comparison with the EFIT flux maps and the experimental magnetic signals are shown. ► A current driven model for the dynamic simulations of the experimental data have been performed. -- Abstract: The aim of this work is to provide reliable linearized models for the design and assessment of a new magnetic control system for MAST (Mega Ampère Spherical Tokamak) using rtEFIT, which can easily be exported to MAST Upgrade. Linearized models for magnetic control have been obtained using the 2D axisymmetric finite element code CREATE L. MAST linearized models include equivalent 2D axisymmetric schematization of poloidal field (PF) coils, vacuum vessel, and other conducting structures. A plasmaless and a double null configuration have been chosen as benchmark cases for the comparison with experimental data and EFIT reconstructions. Good agreement has been found with the EFIT flux map and the experimental signals coming from magnetic probes with only few mismatches probably due to broken sensors. A suite of procedures (equipped with a user friendly interface to be run even remotely) to provide linearized models for magnetic control is now available on the MAST linux machines. A new current driven model has been used to obtain a state space model having the PF coil currents as inputs. Dynamic simulations of experimental data have been carried out using linearized models, including modelling of the effects of the passive structures, showing a fair agreement. The modelling activity has been useful also to reproduce accurately the interaction between plasma current and radial position control loops

Linearized models for a new magnetic control in MAST

Energy Technology Data Exchange (ETDEWEB)

Artaserse, G., E-mail: giovanni.artaserse@enea.it [Associazione Euratom-ENEA sulla Fusione, Via Enrico Fermi 45, I-00044 Frascati (RM) (Italy); Maviglia, F.; Albanese, R. [Associazione Euratom-ENEA-CREATE sulla Fusione, Via Claudio 21, I-80125 Napoli (Italy); McArdle, G.J.; Pangione, L. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom)

2013-10-15

Highlights: ► We applied linearized models for a new magnetic control on MAST tokamak. ► A suite of procedures, conceived to be machine independent, have been used. ► We carried out model-based simulations, taking into account eddy currents effects. ► Comparison with the EFIT flux maps and the experimental magnetic signals are shown. ► A current driven model for the dynamic simulations of the experimental data have been performed. -- Abstract: The aim of this work is to provide reliable linearized models for the design and assessment of a new magnetic control system for MAST (Mega Ampère Spherical Tokamak) using rtEFIT, which can easily be exported to MAST Upgrade. Linearized models for magnetic control have been obtained using the 2D axisymmetric finite element code CREATE L. MAST linearized models include equivalent 2D axisymmetric schematization of poloidal field (PF) coils, vacuum vessel, and other conducting structures. A plasmaless and a double null configuration have been chosen as benchmark cases for the comparison with experimental data and EFIT reconstructions. Good agreement has been found with the EFIT flux map and the experimental signals coming from magnetic probes with only few mismatches probably due to broken sensors. A suite of procedures (equipped with a user friendly interface to be run even remotely) to provide linearized models for magnetic control is now available on the MAST linux machines. A new current driven model has been used to obtain a state space model having the PF coil currents as inputs. Dynamic simulations of experimental data have been carried out using linearized models, including modelling of the effects of the passive structures, showing a fair agreement. The modelling activity has been useful also to reproduce accurately the interaction between plasma current and radial position control loops.

Magnetic levitation configuration incorporating levitation, guidance and linear synchronous motor

Science.gov (United States)

Coffey, Howard T.

1993-01-01

A propulsion and suspension system for an inductive repulsion type magnetically levitated vehicle which is propelled and suspended by a system which includes propulsion windings which form a linear synchronous motor and conductive guideways, adjacent to the propulsion windings, where both combine to partially encircling the vehicle-borne superconducting magnets. A three phase power source is used with the linear synchronous motor to produce a traveling magnetic wave which in conjunction with the magnets propel the vehicle. The conductive guideway combines with the superconducting magnets to provide for vehicle leviation.

Magnetic levitation configuration incorporating levitation, guidance and linear synchronous motor

Science.gov (United States)

Coffey, H.T.

1993-10-19

A propulsion and suspension system for an inductive repulsion type magnetically levitated vehicle which is propelled and suspended by a system which includes propulsion windings which form a linear synchronous motor and conductive guideways, adjacent to the propulsion windings, where both combine to partially encircling the vehicle-borne superconducting magnets. A three phase power source is used with the linear synchronous motor to produce a traveling magnetic wave which in conjunction with the magnets propel the vehicle. The conductive guideway combines with the superconducting magnets to provide for vehicle levitation. 3 figures.

A transcranial magnetic stimulation study of the effect of visual orientation on the putative human mirror neuron system

Directory of Open Access Journals (Sweden)

Jed Donald Burgess

2013-10-01

Full Text Available Mirror neurons are a class of motor neuron that are active during both the performance and observation of behavior, and have been implicated in interpersonal understanding There is evidence to suggest that the mirror response is modulated by the perspective from which an action is presented (e.g., egocentric or allocentric. Most human research, however, has only examined this when presenting intransitive actions. Twenty-three healthy adult participants completed a transcranial magnetic stimulation (TMS experiment that assessed corticospinal excitability whilst viewing transitive hand gestures from both egocentric (i.e., self and allocentric (i.e., other viewpoints. Although action observation was associated with increases in corticospinal excitability (reflecting putative human mirror neuron activity, there was no effect of visual perspective. These findings are discussed in the context of contemporary theories of mirror neuron ontogeny, including models concerning associative learning and evolutionary adaptation.

Mechanical-engineering aspects of mirror-fusion technology

International Nuclear Information System (INIS)

Fisher, D.K.; Doggett, J.N.

1982-01-01

The mirror approach to magnetic fusion has evolved from the original simple mirror cell to today's mainline effort: the tandem-mirror machine with thermal barriers. Physics and engineering research is being conducted throughout the world, with major efforts in Japan, the USSR, and the US. At least one facility under construction (MFTF-B) will approach equivalent energy breakeven in physics performance. Significant mechanical engineering development is needed, however, before a demonstration reactor can be constructed. The principal areas crucial to mirror reactor development include large high-field superconducting magnets, high-speed continuous vacuum-pumping systems, long-pulse high-power neutral-beam and rf-plasma heating systems, and efficient high-voltage high-power direct converters. Other areas common to all fusion systems include tritium handling technology, first-wall materials development, and fusion blanket design

Mirror Birefringence in a Fabry-Perot Cavity and the Detection of Vacuum Birefringence in a Magnetic Field

Science.gov (United States)

Chui, T. C. P.; Shao, M.; Redding, D.; Gursel, Y.; Boden, A.

1995-01-01

We discuss the effect of mirror birefringence in two optical schemes designed to detect the quantum-electrodynamics (QED) predictions of vacuum birefringence under the influence of a strong magnetic field, B. Both schemes make use of a high finesse Fabry-Perot cavity (F-P) to increase the average path length of the light in the magnetic field. The first scheme, which we called the frequency scheme, is based on measurement of the beat frequency of two orthogonal polarized laser beams in the cavity. We show that mirror birefringence contributes to the detection uncertainties in first order, resulting in a high susceptibility to small thermal disturbances. We estimate that an unreasonably high thermal stability of 10-9 K is required to resolve the effect to 0.1%. In the second scheme, which we called the polarization rotation scheme, laser polarized at 45 relative to the B field is injected into the cavity.

On the role of magnetic mirroring in the auroral phenomena

International Nuclear Information System (INIS)

Lennartsson, W.

1976-12-01

On the basis of field and particle observations, it is suggested that a bright auroral display is a part of a magnetosphere-ionosphere current system which is fed by a charge-separation process in the outer magnetosphere (or the solar wind). The upward magnetic-field-aligned current is flowing out of the display, carried mainly by downflowing electrons from the hot-particle populations in the outer magnetosphere (the ambient cold electrons being depleted at high altitudes). As a result of the magnetic mirroring of these downflowing current carriers, a large potential drop is set up along the magnetic field, increasing both the number flux and the kinetic energy of precipitating electrons. It is found that this simple basic model, when combined with wave-particle interactions, may be able to explain a highly diversified selection of auroral particle observations. It may thus be possible to explain both 'inverted-V' events and auroral rays in terms of a static parallel electric field, and the electric field may be compatible with a strongly variable pitch-angle distribution of the precipitating electrons, including distributions peaked at 90 0 as well as 0 0 . This model may also provide a simple explanation of the simultaneous precipitation of electrons and collimated positive ions. (Auth.)

Trieste lectures on mirror symmetry

Energy Technology Data Exchange (ETDEWEB)

Hori, K [Department of Physics and Department of Mathematics, University of Toronto, Toronto, Ontario (Canada)

2003-08-15

These are pedagogical lectures on mirror symmetry given at the Spring School in ICTP, Trieste, March 2002. The focus is placed on worldsheet descriptions of the physics related to mirror symmetry. We start with the introduction to general aspects of (2,2) supersymmetric field theories in 1 + 1 dimensions. We next move on to the study and applications of linear sigma model. Finally, we provide a proof of mirror symmetry in a class of models. (author)

Novel ocean energy permanent magnet linear generator buoy

Energy Technology Data Exchange (ETDEWEB)

Rhinefrank, K.; Agamloh, E.B.; Jouanne, A. von; Wallace, A.K.; Prudell, J.; Kimble, K.; Aills, J.; Schmidt, E.; Schacher, A. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-3211 (United States); Chan, P.; Sweeny, B. [Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331-3211 (United States)

2006-07-15

This paper describes the research, design, construction and prototype testing process of a novel ocean energy direct drive permanent magnet linear generator buoy. The buoy employs the vertical component of the motion of ocean waves to power a linear generator. The generator consists of a permanent magnet field system (mounted on the central translator shaft) and an armature, in which the power is generated (mounted on the buoy). The translator shaft is anchored to the sea floor, and the buoy/floater moves armature coils relative to the permanent magnet translator to induce voltages. The electrical and mechanical structures of the buoy generator are provided, along with performance characteristics, including voltage, current and developed power. (author)

Modification of the magnetic field structure in the vicinity of the x-points by the strong mirror field for a field-reversed configuration (FRC) with the Thick Edge-Layer plasma

International Nuclear Information System (INIS)

Suzuki, Yukihisa; Okada, Shigefumi; Goto, Seiichi

2003-01-01

Modification of the magnetic field structure in the vicinity of the x-points and changes of the separatrix shape are investigated under the pressure effects due to an edge-layer plasma together with a mirror field by the two-dimensional (2-D) MHD equilibrium solutions of field-reversed configuration (FRC) obtained from the Grad-Shafranov equation. To explore the coupling pressure effects caused by edge-layer plasma and mirror field, the equilibrium calculations are performed by the combinations of several values of mirror ratio (R m ) and of edge-layer width (δ), respectively. A summary of results for present study is as follows. In the condition of weak mirror field (1.0 m m > 1.6, ψ=0 surface never opens up for any δ. These original results make it clear that large magnetic curvature produced by the strong mirror field enhances the magnetic stress around the x-point, so that the ends of FRC are effectively sustained by this enhanced magnetic stress, which counteracts the edge-layer plasma pressure effect. (author)

Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic mirrors

Science.gov (United States)

Guérout, R.; Lambrecht, A.; Milton, K. A.; Reynaud, S.

2016-02-01

We examine the conditions of validity for the Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic plane mirrors. As in the previously studied case of nonmagnetic materials [Guérout et al., Phys. Rev. E 90, 042125 (2014), 10.1103/PhysRevE.90.042125], we recover the usual expression for the lossy model of optical response, but not for the lossless plasma model. We also show that the modes associated with the Foucault currents play a crucial role in the limit of vanishing losses, in contrast to expectations.

Standard mirror fusion reactor design study

International Nuclear Information System (INIS)

Moir, R.W.

1978-01-01

This report covers the work of the Magnetic Fusion Energy Division's reactor study group during FY 1976 on the standard mirror reactor. The ''standard'' mirror reactor is characterized as a steady state, neutral beam sustained, D-T fusioning plasma confined by a Yin-Yang magnetic mirror field. The physics parameters are obtained from the same physics model that explains the 2XIIB experiment. The model assumes that the drift cyclotron loss cone mode occurs on the boundary of the plasma, and that it is stabilized by warm plasma with negligible energy investment. The result of the study was a workable mirror fusion power plant, steady-state blanket removal made relatively simple by open-ended geometry, and no impurity problem due to the positive plasma potential. The Q (fusion power/injected beam power) turns out to be only 1.1 because of loss out the ends from Coulomb collisions, i.e., classical losses. This low Q resulted in 77% of the gross electrical power being used to power the injectors, thereby causing the net power cost to be high. The low Q stimulated an intensive search for Q-enhancement concepts, resulting in the LLL reactor design effort turning to the field reversal mirror and the tandem mirror, each having Q of order 5

Linear optical response of carbon nanotubes under axial magnetic field

Science.gov (United States)

Moradian, Rostam; Chegel, Raad; Behzad, Somayeh

2010-04-01

We considered single walled carbon naotubes (SWCNTs) as real three dimensional (3D) systems in a cylindrical coordinate. The optical matrix elements and linear susceptibility, χ(ω), in the tight binding approximation in terms of one-dimensional wave vector, kz and subband index, l are calculated. In an external axial magnetic field optical frequency dependence of linear susceptibility are investigated. We found that axial magnetic field has two effects on the imaginary part of the linear susceptibility spectrum, in agreement with experimental results. The first effect is broadening and the second, splitting. Also we found that for all metallic zigzag and armchair SWCNTs, the axial magnetic field leads to the creation of a peak with energy less than 1.5 eV, contrary to what is observed in the absence of a magnetic field.

Neoclassical resonant transport of a mirror cell

International Nuclear Information System (INIS)

Ito, T.; Katanuma, I.

2005-01-01

The neoclassical resonant plateau transport in a mirror cell is studied theoretically. The analytical expression for a non-square-well magnetic field is obtained. The analytical result is applied to the GAMMA10 tandem mirror [T. Cho, M. Yoshida, J. Kohagura et al., Phys. Rev. Lett. 94, 085002-1 (2005)], which consists of several mirror cells in it, and the confinement time due to the neoclassical resonant plateau transport is determined in each mirror cell. It is found that the neoclassical resonant transport of ions trapped in the nonaxisymmetric anchor mirror cell and transition mirror cells is significantly smaller than those trapped in the central cell

Magnetic Flux Distribution of Linear Machines with Novel Three-Dimensional Hybrid Magnet Arrays

Directory of Open Access Journals (Sweden)

Nan Yao

2017-11-01

Full Text Available The objective of this paper is to propose a novel tubular linear machine with hybrid permanent magnet arrays and multiple movers, which could be employed for either actuation or sensing technology. The hybrid magnet array produces flux distribution on both sides of windings, and thus helps to increase the signal strength in the windings. The multiple movers are important for airspace technology, because they can improve the system’s redundancy and reliability. The proposed design concept is presented, and the governing equations are obtained based on source free property and Maxwell equations. The magnetic field distribution in the linear machine is thus analytically formulated by using Bessel functions and harmonic expansion of magnetization vector. Numerical simulation is then conducted to validate the analytical solutions of the magnetic flux field. It is proved that the analytical model agrees with the numerical results well. Therefore, it can be utilized for the formulation of signal or force output subsequently, depending on its particular implementation.

TMRBAR power balance code for tandem mirror reactors

International Nuclear Information System (INIS)

Blackkfield, D.T.; Campbell, R.; Fenstermacher, M.; Bulmer, R.; Perkins, L.; Peng, Y.K.M.; Reid, R.L.; Wu, K.F.

1984-01-01

A revised version of the tandem mirror multi-point code TMRBAR developed at LLNL has been used to examine various reactor designs using MARS-like ''c'' coils. We solve 14 to 16 non-linear equations to obtain the densities, temperatures, plasma potential and magnetic field on axis at the cardinal points. Since ICRH, ECRH, and neutral beams may be used to stabilize the central cell, various combinations of rf and neutral beam powers may satisfy the physics. To select a desired set of physics parameters, we use nonlinear optimization techniques. Whit these routines, we minimize or maximize a physics variable subject to the physics constraints being satisfied. For example, for a given fusion power we may find the minimum length needed to have an ignited central cell or the maximum fusion Q. Finally, we have coupled this physics model to the LLNL magnetics-MHD code. This code runs the EFFI magnetic field generator and uses TEBASCO to calculate 1-D MHD equilibria and stability

Introduction to tandem mirror physics

International Nuclear Information System (INIS)

Kesner, J.; Gerver, M.J.; Lane, B.G.; McVey, B.D.; Catto, P.J.; D'Ippolito, D.A.; Myra, J.R.

1983-09-01

This monograph, prepared jointly by the MIT Plasma Fusion Center Mirror Fusion group and SAI, Boulder, Colorado, presents a review of the development of mirror fusion theory from its conception some thirty years ago to the present. Pertinent historic experiments and their contribution are discussed to set the stage for a detailed analysis of current experiments and the problems which remain to be solved in bringing tandem mirror magnetic confinement fusion to fruition. In particular, Chapter III discusses in detail the equilibrium and stability questions which must be dealt with before tandem mirror reactors become feasible, while Chapters IV and V discuss some of the current machines and those under construction which will help to resolve critical issues in both physics and engineering whose solutions are necessary to the commercialization of tandem mirror fusion

Observation of transverse and longitudinal modes in non-neutral electron clouds confined in a magnetic mirror

International Nuclear Information System (INIS)

Eckhouse, S.; Fisher, A.; Rostoker, N.

1979-01-01

Electrostatic modes on non-neutral electron clouds confined in a magnetic mirror field have been investigated. The cloud contains 2 x 10 11 electrons at an average kinetic energy of 0.3 MeV for a magnetic field with a peak intensity of 9 kG at the midplane. It was found that the cloud is moving azimuthally as well as longitudinally. The azimuthal motion has an m=1 spatial nature. The longitudinal modes have a more complicated nature, but their frequency equals that of the azimuthal mode

Non-linear spin transport in magnetic semiconductor superlattices

International Nuclear Information System (INIS)

Bejar, Manuel; Sanchez, David; Platero, Gloria; MacDonald, A.H.

2004-01-01

The electronic spin dynamics in DC-biased n-doped II-VI semiconductor multiquantum wells doped with magnetic impurities is presented. Under certain range of electronic doping, conventional semiconductor superlattices present self-sustained oscillations. Magnetically doped wells (Mn) present large spin splittings due to the exchange interaction. The interplay between non-linear interwell transport, the electron-electron interaction and the exchange between electrons and the magnetic impurities produces interesting time-dependent features in the spin polarization current tuned by an external magnetic field

Spatial configuration of a plasma bunch formed under gyromagnetic resonance in a magnetic mirror trap

Energy Technology Data Exchange (ETDEWEB)

Andreev, V. V.; Novitskii, A. A.; Umnov, A. M.; Chuprov, D. V., E-mail: chu-d@mail.ru [Peoples’ Friendship University of Russia (Russian Federation)

2016-06-15

The spatial configuration of a relativistic plasma bunch generated under the gyromagnetic autoresonance and confined in a magnetic mirror trap has been studied experimentally and numerically. The characteristics of bremsstrahlung generated by the plasma bunch from the gas and chamber walls were investigated using X-ray spectroscopy and radiometry, which made it possible to determine the localization of the bunch and analyze the dynamics of its confinement.

Estimation of non-linear effective permeability of magnetic materials with fine structure

International Nuclear Information System (INIS)

Waki, H.; Igarashi, H.; Honma, T.

2006-01-01

This paper describes a homogenization method for magnetic materials with fine structure. In this method, the structures of the magnetic materials are assumed to be periodic, and the unit cell is defined. The effective permeability is determined on the basis of magnetic energy balance in the unit cell. This method can be applied not only for linear problems but also for non-linear ones. In this paper, estimation of the effective permeability of non-linear magnetic materials by using the homogenization method is described in detail, and then the validity for the non-liner problems is tested for two-dimensional problems. It is shown that this homogenization method gives accurate non-linear effective permeability

Measurements of Rayleigh-Taylor-Induced Magnetic Fields in the Linear and Non-linear Regimes

Science.gov (United States)

Manuel, Mario

2012-10-01

Magnetic fields are generated in plasmas by the Biermann-battery, or thermoelectric, source driven by non-collinear temperature and density gradients. The ablation front in laser-irradiated targets is susceptible to Rayleigh-Taylor (RT) growth that produces gradients capable of generating magnetic fields. Measurements of these RT-induced magnetic fields in planar foils have been made using a combination of x-ray and monoenergetic-proton radiography techniques. At a perturbation wavelength of 120 μm, proton radiographs indicate an increase of the magnetic-field strength from ˜1 to ˜10 Tesla during the linear growth phase. A characteristic change in field structure was observed later in time for irradiated foils of different initial surface perturbations. Proton radiographs show a regular cellular configuration initiated at the same time during the drive, independent of the initial foil conditions. This non-linear behavior has been experimentally investigated and the source of these characteristic features will be discussed.

Mechanical design aspects of a tandem mirror fusion reactor

International Nuclear Information System (INIS)

Neef, W.S. Jr.

1977-01-01

Two ''plugs'' of dense plasma at either end of a central solenoid cell form the basis of a new mirror fusion power plant concept. A central cell blanket design is presented. Modules on crawler tracks serviced by remote welding and handling machines of very simple design are important features resulting from linear axisymmetric geometry. Three blanket designs are considered and the best one presented in some detail. It has lithium as the breeder material, helium cooled. ''Plug'' magnet field strengths must be high. A novel magnet is presented to satisfy the physics of the end plugs. Beam sources at 1,200 KV present special problems. Methods of voltage standoff, arc damage control, and neutralization are discussed. New secondary containment ideas are presented to allow removable roof sections of balanced design

Magneto-hydrodynamically stable axisymmetric mirrors

Energy Technology Data Exchange (ETDEWEB)

Ryutov, D. D.; Cohen, B. I.; Molvik, A. W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Berk, H. L. [University of Texas, Austin, Texas 78712 (United States); Simonen, T. C. [University of California, Berkeley, California 94720 (United States)

2011-09-15

Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.

Mirror fusion test facility

International Nuclear Information System (INIS)

Post, R.F.

1978-01-01

The MFTF is a large new mirror facility under construction at Livermore for completion in 1981--82. It represents a scaleup, by a factor of 50 in plasma volume, a factor of 5 or more in ion energy, and a factor of 4 in magnetic field intensity over the Livermore 2XIIB experiment. Its magnet, employing superconducting NbTi windings, is of Yin-Yang form and will weigh 200 tons. MFTF will be driven by neutral beams of two levels of current and energy: 1000 amperes of 20 keV (accelerating potential) pulsed beams for plasma startup; 750 amperes of 80 keV beams of 0.5 second duration for temperature buildup and plasma sustainment. Two operating modes for MFTF are envisaged: The first is operation as a conventional mirror cell with n/sup tau/ approximately equal to 10 12 cm -3 sec, W/sub i/ = 50 keV, where the emphasis will be on studying the physics of mirror cells, particularly the issues of improved techniques of stabilization against ion cyclotron modes and of maximization of the electron temperature. The second possible mode is the further study of the Field Reversed Mirror idea, using high current neutral beams to sustain the field-reversed state. Anticipating success in the coming Livermore Tandem Mirror Experiment (TMX) MFTF has been oriented so that it could comprise one end cell of a scaled up TM experiment. Also, if MFTF were to succeed in achieving a FR state it could serve as an essentially full-sized physics prototype of one cell of a FRM fusion power plant

Design, analysis and fabrication of a linear permanent magnet ...

Indian Academy of Sciences (India)

MONOJIT SEAL

Linear permanent magnet synchronous machine; LPMSM—fabrication; design optimisation; finite-element ... induction motor (LIM) prototype was patented in 1890 [1]. Since then, linear ..... Also, for manual winding, more slot area is allotted to ...

Linear and nonlinear electrostatic modes in a nonuniform magnetized electron plasma

International Nuclear Information System (INIS)

Vranjes, J.; Shukla, P.K.; Kono, M.; Poedts, S.

2001-01-01

Linear and nonlinear low-frequency modes in a magnetized electron plasma are studied, taking into account a proper description of the equilibrium plasma state that is inhomogeneous. Assuming a homogeneous magnetic field and sheared plasma flows, flute-like perturbations are studied in the presence of density and potential gradients. Linear analysis reveals the presence of a streaming instability and depicts conditions for global linear spiral mode. In the nonlinear domain, a tripolar vortex, which is driven and carried by the flow, is found. Also investigated are the consequences of a magnetic shear as well as nonuniformities along the magnetic field lines, which are shown to be responsible for the possible annulment of the magnetic shear effects. Streaming along the lines of the sheared magnetic field is also studied. A variety of nonlinear structures (viz. global multipolar vortices, local vortex chains, and tripolar vortices) is shown to be the consequence of the simultaneous action of the parallel and perpendicular flows

PARTICLE-IN-CELL SIMULATIONS OF CONTINUOUSLY DRIVEN MIRROR AND ION CYCLOTRON INSTABILITIES IN HIGH BETA ASTROPHYSICAL AND HELIOSPHERIC PLASMAS

International Nuclear Information System (INIS)

Riquelme, Mario A.; Quataert, Eliot; Verscharen, Daniel

2015-01-01

We use particle-in-cell simulations to study the nonlinear evolution of ion velocity space instabilities in an idealized problem in which a background velocity shear continuously amplifies the magnetic field. We simulate the astrophysically relevant regime where the shear timescale is long compared to the ion cyclotron period, and the plasma beta is β ∼ 1-100. The background field amplification in our calculation is meant to mimic processes such as turbulent fluctuations or MHD-scale instabilities. The field amplification continuously drives a pressure anisotropy with p > p ∥ and the plasma becomes unstable to the mirror and ion cyclotron instabilities. In all cases, the nonlinear state is dominated by the mirror instability, not the ion cyclotron instability, and the plasma pressure anisotropy saturates near the threshold for the linear mirror instability. The magnetic field fluctuations initially undergo exponential growth but saturate in a secular phase in which the fluctuations grow on the same timescale as the background magnetic field (with δB ∼ 0.3 (B) in the secular phase). At early times, the ion magnetic moment is well-conserved but once the fluctuation amplitudes exceed δB ∼ 0.1 (B), the magnetic moment is no longer conserved but instead changes on a timescale comparable to that of the mean magnetic field. We discuss the implications of our results for low-collisionality astrophysical plasmas, including the near-Earth solar wind and low-luminosity accretion disks around black holes

The spinning Kerr-black-hole-mirror bomb: A lower bound on the radius of the reflecting mirror

Science.gov (United States)

Hod, Shahar

2016-10-01

The intriguing superradiant amplification phenomenon allows an orbiting scalar field to extract rotational energy from a spinning Kerr black hole. Interestingly, the energy extraction rate can grow exponentially in time if the black-hole-field system is placed inside a reflecting mirror which prevents the field from radiating its energy to infinity. This composed Kerr-black-hole-scalar-field-mirror system, first designed by Press and Teukolsky, has attracted the attention of physicists over the last four decades. Previous numerical studies of this spinning black-hole bomb have revealed the interesting fact that the superradiant instability shuts down if the reflecting mirror is placed too close to the black-hole horizon. In the present study we use analytical techniques to explore the superradiant instability regime of this composed Kerr-black-hole-linearized-scalar-field-mirror system. In particular, it is proved that the lower bound rm/r+ >1/2 (√{ 1 +8M/r- } - 1) provides a necessary condition for the development of the exponentially growing superradiant instabilities in this composed physical system, where rm is the radius of the confining mirror and r± are the horizon radii of the spinning Kerr black hole. We further show that, in the linearized regime, this analytically derived lower bound on the radius of the confining mirror agrees with direct numerical computations of the superradiant instability spectrum which characterizes the spinning black-hole-mirror bomb.

Properties and parameters of the electron beam injected into the mirror magnetic trap of a plasma accelerator

Energy Technology Data Exchange (ETDEWEB)

Andreev, V. V., E-mail: temple18@mail.ru; Novitsky, A. A.; Vinnichenko, L. A.; Umnov, A. M.; Ndong, D. O. [Peoples’ Friendship University of Russia (Russian Federation)

2016-03-15

The parameters of the injector of an axial plasma beam injected into a plasma accelerator operating on the basis of gyroresonance acceleration of electrons in the reverse magnetic field are determined. The trapping of the beam electrons into the regime of gyroresonance acceleration is numerically simulated by the particle- in-cell method. The optimal time of axial injection of the beam into a magnetic mirror trap is determined. The beam parameters satisfying the condition of efficient particle trapping into the gyromagnetic autoresonance regime are found.

Modeling of non-ideal hard permanent magnets with an affine-linear model, illustrated for a bar and a horseshoe magnet

Science.gov (United States)

Glane, Sebastian; Reich, Felix A.; Müller, Wolfgang H.

2017-11-01

This study is dedicated to continuum-scale material modeling of isotropic permanent magnets. An affine-linear extension to the commonly used ideal hard model for permanent magnets is proposed, motivated, and detailed. In order to demonstrate the differences between these models, bar and horseshoe magnets are considered. The structure of the boundary value problem for the magnetic field and related solution techniques are discussed. For the ideal model, closed-form analytical solutions were obtained for both geometries. Magnetic fields of the boundary value problems for both models and differently shaped magnets were computed numerically by using the boundary element method. The results show that the character of the magnetic field is strongly influenced by the model that is used. Furthermore, it can be observed that the shape of an affine-linear magnet influences the near-field significantly. Qualitative comparisons with experiments suggest that both the ideal and the affine-linear models are relevant in practice, depending on the magnetic material employed. Mathematically speaking, the ideal magnetic model is a special case of the affine-linear one. Therefore, in applications where knowledge of the near-field is important, the affine-linear model can yield more accurate results—depending on the magnetic material.

Linear Magnetoelectric Effect by Orbital Magnetism

NARCIS (Netherlands)

Scaramucci, A.; Bousquet, E.; Fechner, M.; Mostovoy, M.; Spaldin, N. A.

2012-01-01

We use symmetry analysis and first-principles calculations to show that the linear magnetoelectric effect can originate from the response of orbital magnetic moments to the polar distortions induced by an applied electric field. Using LiFePO4 as a model compound we show that spin-orbit coupling

A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

Directory of Open Access Journals (Sweden)

Yi Sui

2017-05-01

Full Text Available A single-phase tubular permanent-magnet linear machine (PMLM with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA. The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

Science.gov (United States)

Sui, Yi; Liu, Yong; Cheng, Luming; Liu, Jiaqi; Zheng, Ping

2017-05-01

A single-phase tubular permanent-magnet linear machine (PMLM) with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA). The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

Normal form for mirror machine Hamiltonians

International Nuclear Information System (INIS)

Dragt, A.J.; Finn, J.M.

1979-01-01

A systematic algorithm is developed for performing canonical transformations on Hamiltonians which govern particle motion in magnetic mirror machines. These transformations are performed in such a way that the new Hamiltonian has a particularly simple normal form. From this form it is possible to compute analytic expressions for gyro and bounce frequencies. In addition, it is possible to obtain arbitrarily high order terms in the adiabatic magnetic moment expansion. The algorithm makes use of Lie series, is an extension of Birkhoff's normal form method, and has been explicitly implemented by a digital computer programmed to perform the required algebraic manipulations. Application is made to particle motion in a magnetic dipole field and to a simple mirror system. Bounce frequencies and locations of periodic orbits are obtained and compared with numerical computations. Both mirror systems are shown to be insoluble, i.e., trajectories are not confined to analytic hypersurfaces, there is no analytic third integral of motion, and the adiabatic magnetic moment expansion is divergent. It is expected also that the normal form procedure will prove useful in the study of island structure and separatrices associated with periodic orbits, and should facilitate studies of breakdown of adiabaticity and the onset of ''stochastic'' behavior

Mirror Fusion vacuum technology developments

International Nuclear Information System (INIS)

Batzer, T.H.; Call, W.R.

1983-01-01

Magnetic Mirror Fusion experiments, such as MFTF-B+T (Mirror Fusion Test Facility-B, Tritium Upgrade) and foreseeable follow-on devices, have operational and maintenance requirements that have not yet been fully demonstrated. Among those associated with vacuum technology are the very-high continuous-pumping speeds, 10 7 to 10 8 l/s for D 2 , T 2 and, to a lesser extent, He; the early detection of water leaks from the very-high heat-flux neutral-beam dumps and the detection and location of leaks in the superconducting magnets not protected by guard vacuums. Possible solutions to these problems have been identified and considerable progress has been made toward successfully demonstrating their feasibility

Mirror fusion vacuum technology developments

International Nuclear Information System (INIS)

Batzer, T.H.; Call, W.R.

1983-01-01

Magnetic Mirror Fusion experiments, such as MFTF-B+T (Mirror Fusion Test Facility-B, Tritium Upgrade) and foreseeable follow-on devices, have operational and maintenance requirements that have not yet been fully demonstrated. Among those associated with vacuum technology are the very-high continuous-pumping speeds, 10 7 to 10 8 l/s for D 2 , T 2 and, to a lesser extent, He; the early detection of water leaks from the very-high heat-flux neutral-beam dumps and the detection and location of leaks in the superconducting magnets not protected by guard vacuums. Possible solutions to these problems have been identified and considerable progress has been made toward successfully demonstrating their feasibility

Mirror power reactor magnet coil system: a technically and economically feasible design

International Nuclear Information System (INIS)

Peterson, M.A.

1977-01-01

The design and preliminary engineering analysis of a ''Yin Yang'' coil system utilizing several original design concepts to achieve technical and economic feasibility will be presented. The design analysis is begun with a general description of the constraints and prerequisites which define the problem of designing a satisfactory coil system for a mirror power reactor. This description includes a discussion of the coil conductor geometry required by plasma physics considerations, and also a description of the magnitude and direction of the magnetic force system distributed over the conductor geometry. In addition, the important design constraints which all mirror coil system designs must satisfy if they are to successfully interface with the other reactor components are reviewed. After considering the basic constraints that Yin Yong coil systems must be developed around, a survey of the various design concepts that were developed and explored in search of a satisfactory coil system design is discussed. From this extensive preliminary investigation of potential coil system configurations, a coil system design was developed which appears to offer by far the best combination of technical and economic feasibility of any other coil system design developed thus far

Non linear permanent magnets modelling with the finite element method

International Nuclear Information System (INIS)

Chavanne, J.; Meunier, G.; Sabonnadiere, J.C.

1989-01-01

In order to perform the calculation of permanent magnets with the finite element method, it is necessary to take into account the anisotropic behaviour of hard magnetic materials (Ferrites, NdFeB, SmCo5). In linear cases, the permeability of permanent magnets is a tensor. This one is fully described with the permeabilities parallel and perpendicular to the easy axis of the magnet. In non linear cases, the model uses a texture function which represents the distribution of the local easy axis of the cristallytes of the magnet. This function allows a good representation of the angular dependance of the coercitive field of the magnet. As a result, it is possible to express the magnetic induction B and the tensor as functions of the field and the texture parameter. This model has been implemented in the software FLUX3D where the tensor is used for the Newton-Raphson procedure. 3D demagnetization of a ferrite magnet by a NdFeB magnet is a suitable representative example. They analyze the results obtained for an ideally oriented ferrite magnet and a real one using a measured texture parameter

Simulation of magnetic induction distribution in a coaxial linear motor with axial and radial direction of permanent magnets magnetization

Directory of Open Access Journals (Sweden)

G.M. Golenkov

2014-03-01

Full Text Available The paper presents results of computer simulation and experimental study of magnetic induction distribution in a coaxial linear motor air gap throughout the length of the runner active part at different heights of the air gap between the runner and the inductor magnetic core for motors with axial and radial direction of the permanent magnets magnetization.

Beamline 9.3.2 - a high-resolution, bend-magnet beamline with circular polarization capability

Energy Technology Data Exchange (ETDEWEB)

Moler, E.J.; Hussain, Z.; Howells, M.R. [Lawrence Berkeley National Lab., CA (United States)] [and others

1997-04-01

Beamline 9.3.2 is a high resolution, SGM beamline on an ALS bending magnet with access to photon energies from 30-1500 eV. Features include circular polarization capability, a rotating chamber platform that allows switching between experiments without breaking vacuum, an active feedback system that keeps the beam centered on the entrance slit of the monochromator, and a bendable refocusing mirror. The beamline optics consist of horizontally and vertically focussing mirrors, a Spherical Grating Monochromator (SGM) with movable entrance and exit slits, and a bendable refocussing mirror. In addition, a movable aperature has been installed just upstream of the vertically focussing mirror which can select the x-rays above or below the plane of the synchrotron storage ring, allowing the user to select circularly or linearly polarized light. Circularly polarized x-rays are used to study the magnetic properties of materials. Beamline 9.3.2 can supply left and right circularly polarized x-rays by a computer controlled aperture which may be placed above or below the plane of the synchrotron storage ring. The degree of linear and circular polarization has been measured and calibrated.

Confinement and Isotropization of Galactic Cosmic Rays by Molecular-Cloud Magnetic Mirrors When Turbulent Scattering Is Weak

International Nuclear Information System (INIS)

Chandran, Benjamin D. G.

2000-01-01

Theoretical studies of magnetohydrodynamic (MHD) turbulence and observations of solar wind fluctuations suggest that MHD turbulence in the interstellar medium is anisotropic at small scales, with smooth variations along the background magnetic field and sharp variations perpendicular to the background field. Turbulence with this anisotropy is inefficient at scattering cosmic rays, and thus the scattering rate ν may be smaller than has been traditionally assumed in diffusion models of Galactic cosmic-ray propagation, at least for cosmic-ray energies E above 1011-1012 eV at which self-confinement is not possible. In this paper, it is shown that Galactic cosmic rays can be effectively confined through magnetic reflection by molecular clouds, even when turbulent scattering is weak. Elmegreen's quasi-fractal model of molecular-cloud structure is used to argue that a typical magnetic field line passes through a molecular cloud complex once every ∼300 pc. Once inside the complex, the field line will in most cases be focused into one or more dense clumps in which the magnetic field can be much stronger than the average field in the intercloud medium (ICM). Cosmic rays following field lines into cloud complexes are most often magnetically reflected back into the ICM, since strong-field regions act as magnetic mirrors. For a broad range of cosmic-ray energies, a cosmic ray initially following some particular field line separates from that field line sufficiently slowly that the cosmic ray can be trapped between neighboring cloud complexes for long periods of time. The suppression of cosmic-ray diffusion due to magnetic trapping is calculated in this paper with the use of phenomenological arguments, asymptotic analysis, and Monte Carlo particle simulations. Formulas for the coefficient of diffusion perpendicular to the Galactic disk are derived for several different parameter regimes within the E-ν plane. In one of these parameter regimes in which scattering is weak, it

Stanford Linear Collider magnet positioning

International Nuclear Information System (INIS)

Wand, B.T.

1991-08-01

For the installation of the Stanford Linear Collider (SLC) the positioning and alignment of the beam line components was performed in several individual steps. In the following the general procedures for each step are outlined. The calculation of ideal coordinates for the magnets in the entire SLC will be discussed in detail. Special emphasis was given to the mathematical algorithms and geometry used in the programs to calculate these ideal positions. 35 refs., 21 figs

Preliminary experimental results from a linear reciprocating magnetic refrigerator prototype

International Nuclear Information System (INIS)

Tagliafico, Luca Antonio; Scarpa, Federico; Valsuani, Federico; Tagliafico, Giulio

2013-01-01

A linear reciprocating magnetic refrigerator prototype was designed and built with the aid of an industrial partner. The refrigerator is based on the Active Magnetic Regenerative cycle, and exploits two regenerators working in parallel. The active material is Gadolinium in plates, 0.8 mm thick, for a total mass of 0.36 kg. The device is described and results about magnetic field and temperature span measurements are presented. The designed permanent magnet structure, based on an improved cross-type arrangement, generates a maximum magnetic field intensity of 1.55 T in air, over a gap of (13 × 50 × 100) mm 3 . The maximum temperature span achieved is 5.0 K, in a free run condition. -- Highlights: ► We give preliminary results from a linear reciprocating magnetic refrigerator prototype. ► The design is intended to process visualization and investigation. ► The prototype behavior gives us various suggestions to improve its general performance

Linear magnetic spring and spring/motor combination

Science.gov (United States)

Patt, Paul J. (Inventor); Stolfi, Fred R. (Inventor)

1991-01-01

A magnetic spring, or a spring and motor combination, providing a linear spring force characteristic in each direction from a neutral position, in which the spring action may occur for any desired coordinate of a typical orthogonal coordinate system. A set of magnets are disposed, preferably symmetrically about a coordinate axis, poled orthogonally to the desired force direction. A second set of magnets, respectively poled opposite the first set, are arranged on the sprung article. The magnets of one of the sets are spaced a greater distance apart than those of the other, such that an end magnet from each set forms a pair having preferably planar faces parallel to the direction of spring force, the faces being offset so that in a neutral position the outer edge of the closer spaced magnet set is aligned with the inner edge of the greater spaced magnet set. For use as a motor, a coil can be arranged with conductors orthogonal to both the magnet pole directions and the direction of desired spring force, located across from the magnets of one set and fixed with respect to the magnets of the other set. In a cylindrical coordinate system having axial spring force, the magnets are radially poled and motor coils are concentric with the cylinder axis.

Novel Approach to Linear Accelerator Superconducting Magnet System

International Nuclear Information System (INIS)

Kashikhin, Vladimir

2011-01-01

Superconducting Linear Accelerators include a superconducting magnet system for particle beam transportation that provides the beam focusing and steering. This system consists of a large number of quadrupole magnets and dipole correctors mounted inside or between cryomodules with SCRF cavities. Each magnet has current leads and powered from its own power supply. The paper proposes a novel approach to magnet powering based on using superconducting persistent current switches. A group of magnets is powered from the same power supply through the common, for the group of cryomodules, electrical bus and pair of current leads. Superconducting switches direct the current to the chosen magnet and close the circuit providing the magnet operation in a persistent current mode. Two persistent current switches were fabricated and tested. In the paper also presented the results of magnetic field simulations, decay time constants analysis, and a way of improving quadrupole magnetic center stability. Such approach substantially reduces the magnet system cost and increases the reliability.

Performance Comparison of Permanent Magnet Linear Actuators of Different Mover Types

DEFF Research Database (Denmark)

Ritchie, Ewen; Hinov, K.; Yatchev, I.

2006-01-01

A comparative study of permanent magnet linear actuators with different location of the permanent magnet is reported. Three mover types are considered - soft magnetic mover, permanent magnet mover and hybrid mover. Force-stroke characteristics are obtained with the help of finite element models...

Maintenance of a multi-cell field reversed mirror reactor

International Nuclear Information System (INIS)

Neef, W.S. Jr.

1978-01-01

The Field Reversed Mirror Reactor is composed of a horizontal linear chain of cells, each of which requires neutral beam injection. Blanket replacement is achieved by lifting one complete cell module from the reactor and replacing it with a preassembled and tested identical module. Ioffe bar connectors eliminate redundant bus bars. Asymmetric cell design simplifies magnet construction and reduces replacement time. A tapered cylindrical coolant distributor simplifies blanket removal. An evacuated housing surrounds the reactor reducing cell-to-cell sealing problems related to maintenance. Remote couplings are used for coolant and accessories. Hot-cell location and design permits immediate reconditioning or storage of replacement cells

Superstrong Adjustable Permanent Magnet for a Linear Collider Final Focus

CERN Document Server

Iwashita, Y

2004-01-01

Super-strong permanent magnets are being considered as one of the candidates for the final focus quadrupole magnets in a linear collider. A short prototype with temperature compensation included and variable strength capability has been designed and fabricated. Fabrication details and some magnetic measurement results will be presented.

Mirror monochromator

Energy Technology Data Exchange (ETDEWEB)

Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States); Shadman, Khashayar [Electron Optica, Inc., Palo Alto, CA (United States)

2014-12-02

In this SBIR project, Electron Optica, Inc. (EOI) is developing a mirror electron monochromator (MirrorChrom) attachment to new and retrofitted electron microscopes (EMs) for improving the energy resolution of the EM from the characteristic range of 0.2-0.5 eV to the range of 10-50 meV. This improvement will enhance the characterization of materials by imaging and spectroscopy. In particular, the monochromator will refine the energy spectra characterizing materials, as obtained from transmission EMs [TEMs] fitted with electron spectrometers, and it will increase the spatial resolution of the images of materials taken with scanning EMs (SEMs) operated at low voltages. EOI’s MirrorChrom technology utilizes a magnetic prism to simultaneously deflect the electron beam off the axis of the microscope column by 90° and disperse the electrons in proportional to their energies into a module with an electron mirror and a knife-edge. The knife-edge cuts off the tails of the energy distribution to reduce the energy spread of the electrons that are reflected, and subsequently deflected, back into the microscope column. The knife-edge is less prone to contamination, and thereby charging, than the conventional slits used in existing monochromators, which improves the reliability and stability of the module. The overall design of the MirrorChrom exploits the symmetry inherent in reversing the electron trajectory in order to maintain the beam brightness – a parameter that impacts how well the electron beam can be focused downstream onto a sample. During phase I, EOI drafted a set of candidate monochromator architectures and evaluated the trade-offs between energy resolution and beam current to achieve the optimum design for three particular applications with market potential: increasing the spatial resolution of low voltage SEMs, increasing the energy resolution of low voltage TEMs (beam energy of 5-20 keV), and increasing the energy resolution of conventional TEMs (beam

Streaming-plasma measurements in the Baseball II-T mirror experiment

International Nuclear Information System (INIS)

Damm, C.C.; Foote, J.H.; Futch, A.H.; Goodman, R.K.; Hornady, R.S.; Osher, J.E.; Porter, G.D.

1977-01-01

The warm plasma from a deuterium-loaded titanium washer gun, streaming along magnetic-field lines through the steady-state magnetic well of Baseball II, has been examined for its suitability in this experimental situation as a target plasma for hot-ion buildup experiments and for microinstability control. The gun was positioned near the magnetic axis outside the mirror region. Measurements were made with gridded, end-loss detectors placed outside the opposite mirror, a microwave interferometer, a beam-attenuation detector, and other diagnostics

Present status of mirror stability theory

International Nuclear Information System (INIS)

Baldwin, D.E.; Berk, H.L.; Byers, J.A.

1976-01-01

A status report of microinstability as it applies to 2XIIB and MX theory for mirror machines is presented. It is shown that quasilinear computations reproduce many of the parameters observed in the 2XIIB experiment. In regard to large mirror machines, there are presented detailed calculations of the linear theory of the drift cyclotron loss-cone mode, with inhomogeneous geometry and nonlinear diffusive effects. Further, the stability of a mirror machine to the Alfven ion-cyclotron instability is assessed, and the Baldwin-Callen diffusion is estimated for a spatially varying plasma

Modeling and analysis of mover gaps in tubular moving-magnet linear oscillating motors

Directory of Open Access Journals (Sweden)

Xuesong LUO

2018-05-01

Full Text Available A tubular moving-magnet linear oscillating motor (TMMLOM has merits of high efficiency and excellent dynamic capability. To enhance the thrust performance, quasi-Halbach permanent magnet (PM arrays are arranged on its mover in the application of a linear electro-hydrostatic actuator in more electric aircraft. The arrays are assembled by several individual segments, which lead to gaps between them inevitably. To investigate the effects of the gaps on the radial magnetic flux density and the machine thrust in this paper, an analytical model is built considering both axial and radial gaps. The model is validated by finite element simulations and experimental results. Distributions of the magnetic flux are described in condition of different sizes of radial and axial gaps. Besides, the output force is also discussed in normal and end windings. Finally, the model has demonstrated that both kinds of gaps have a negative effect on the thrust, and the linear motor is more sensitive to radial ones. Keywords: Air-gap flux density, Linear motor, Mover gaps, Quasi-Halbach array, Thrust output, Tubular moving-magnet linear oscillating motor (TMMLOM

Investigation and Calculation of Magnetic Field in Tubular Linear Reluctance Motor Using FEM

Directory of Open Access Journals (Sweden)

MOSALLANEJAD, A.

2010-11-01

Full Text Available In this paper the magnetic flux density of tubular linear reluctance motor (TLRM in open type magnetic circuit is studied. Also, all magnetic flux density calculation methods in winding of tubular linear reluctance motor are described. The effect of structure parameters on magnetic flux density is also discussed. Electromagnetic finite-element analysis is used for simulation of magnetic field, and simulation results of the magnetic field analysis with DC voltage excitation are compared with results obtained from calculation methods. The comparison yields a good agreement.

Optimization of Linear Permanent Magnet (PM Generator with Triangular-Shaped Magnet for Wave Energy Conversion using Finite Element Method

Directory of Open Access Journals (Sweden)

Aamir Hussain

2016-06-01

Full Text Available This paper presents the design optimization of linear permanent magnet (PM generator for wave energy conversion using finite element method (FEM. A linear PM generator with triangular-shaped magnet is proposed, which has higher electromagnetic characteristics, superior performance and low weight as compared to conventional linear PM generator with rectangular shaped magnet. The Individual Parameter (IP optimization technique is employed in order to optimize and achieve optimum performance of linear PM generator. The objective function, optimization variables; magnet angle,M_θ(∆ (θ, the pole-width ratio, P_w ratio(τ_p/τ_mz,, and split ratio between translator and stator, δ_a ratio(R_m/R_e, and constraints are defined. The efficiency and its main parts; copper and iron loss are computed using time-stepping FEM. The optimal values after optimization are presented which yields highest efficiency. Key

Mirror reactor studies

International Nuclear Information System (INIS)

Moir, R.W.; Barr, W.L.; Bender, D.J.

1976-01-01

Design studies of a fusion mirror reactor, a fusion-fission mirror reactor, and two small mirror reactors are summarized. The fusion reactor uses 150-keV neutral-beam injectors based on the acceleration of negative ions. The injectors provide over 1 GW of continuous power at an efficiency greater than 80 percent. The fusion reactor has three-stage, modularized, Venetian blind, plasma direct converter with a predicted efficiency of 59 percent and a new concept for removal of the lune-shaped blanket: a crane is brought between the two halves of the Yin-Yang magnet, which are separated by a float. The design has desirable features such as steady-state operation, minimal impurity problems, and low first-wall thermal stress. The major disadvantage is low Q resulting in high recirculating power and hence high cost of electrical power. However, the direct capital cost per unit of gross electrical power is reasonable [$1000/kW(e)

Linear magnetic fusion: summary of Seattle workshop

International Nuclear Information System (INIS)

1977-12-01

The linear-geometry magnetic confinement concept is among the oldest used in the study of high-temperature plasmas. However, it has generally been discounted as a suitable approach for demonstrating controlled thermonuclear fusion because rapid losses from the plasma column ends necessitate very long devices. Further, the losses and how to overcome them have not yet received parametric experimental study, nor do facilities exist with which such definitive experiments could be performed. Nonetheless, the important positive attribute, simplicity, together with the appearance of several ideas for reducing end losses have provided motivation for continued research on linear magnetic fusion (LMF). These motivations led to the LMF workshop, held in Seattle, March 9--11, 1977, which explored the potential of LMF as an alternate approach to fusion. A broad range of LMF aspects were addressed, including radial and axial losses, stability and equilibrium, heating, technology, and reactor considerations. The conclusions drawn at the workshop are summarized

Metamaterial mirrors in optoelectronic devices

KAUST Repository

Esfandyarpour, Majid; Garnett, Erik C.; Cui, Yi; McGehee, Michael D.; Brongersma, Mark L.

2014-01-01

The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror († = €) to that of a perfect magnetic mirror († = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band. © 2014 Macmillan Publishers Limited.

Metamaterial mirrors in optoelectronic devices

KAUST Repository

Esfandyarpour, Majid

2014-06-22

The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror († = €) to that of a perfect magnetic mirror († = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band. © 2014 Macmillan Publishers Limited.

A non-linear dissipative model of magnetism

Czech Academy of Sciences Publication Activity Database

Durand, P.; Paidarová, Ivana

2010-01-01

Roč. 89, č. 6 (2010), s. 67004 ISSN 1286-4854 R&D Projects: GA AV ČR IAA100400501 Institutional research plan: CEZ:AV0Z40400503 Keywords : non-linear dissipative model of magnetism * thermodynamics * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry http://epljournal.edpsciences.org/

Determination of Local Magnetic Dipole Moment of the Plasma at the PUPR Cusp-Mirror Machine

International Nuclear Information System (INIS)

Leal-Quiros, Edbertho; Prelas, Mark

2006-01-01

A novel diagnostic that allows measurement of the magnetic moment μ has been designed. The μ-Analyzer consists of a Directional Energy Analyzer and a Magnetic Hall Probe in the same detector miniature case. The Directional Energy Analyzer measures the ion temperature in the perpendicular direction to the magnetic field. On the other side, the Hall Probe measures the magnetic field. The μ-Analyzer is a miniature analyzer to avoid plasma perturbation. This allows the measurement of the ion temperature and the local magnetic field at the same point at the same time, therefore μ, the first adiabatic invariant is found. From the above parameters, the local Larmor radius also will be calculated. From the analysis of the data simultaneously in time and space, the μ of the Local Plasma has been determined. This result is a very important quantity, among other properties that permit one to know the stability of the magnetic confinement device using the MHD Stability Criterium, and also very important in Space Plasma Research. In addition to the above, a direct measurement of the Larmor radius of each position is also possible. The experiments have been made in a Cusp/Mirror Plasma Machine where plasma parameters such as Density and Temperature are relatively easy to change in a very wide range

Linear birefringence and optical ativity in a magnetized plasma

International Nuclear Information System (INIS)

Vuolo, J.H.; Galvao, R.M.O.

1982-02-01

Linear birefringence and optical activity are considered separately to electromagnetic wave propagation in magnetized cold plasma, using frequency approximation much bigger than plasma frequency. It's showen that in some interesting cases, those phenomena could be independents. Explicit expressions are obtained for refraction indices to linear birefringency and optical activity. The correspondents indices attenuation aRe obtained in first orden of attenuation. It's showen that the characteristic states for linear dichroism coincide with the characteristic states for linear birefringence. The characteristic states for elliptic dichroism are obtained. (M.A.F.) [pt

AIRGAP MAGNETIC INDUCTION DISTRIBUTION IN A COAXIALLY-LINEAR SYNCHRONOUS MOTOR WITH AXIAL AND RADIAL DIRECTION OF THE RUNNER PERMANENT MAGNETS MAGNETIZATION

Directory of Open Access Journals (Sweden)

Abbasian Mohsen

2013-02-01

Full Text Available Results of theoretical and experimental research on magnetic induction distribution in the air gap of a coaxially-linear synchronous motor with reciprocal motion within the pole pitch and axial and radial direction of the permanent magnets magnetization are presented.

Electrostatic polymer-based microdeformable mirror for adaptive optics

Science.gov (United States)

Zamkotsian, Frederic; Conedera, Veronique; Granier, Hugues; Liotard, Arnaud; Lanzoni, Patrick; Salvagnac, Ludovic; Fabre, Norbert; Camon, Henri

2007-02-01

Future adaptive optics (AO) systems require deformable mirrors with very challenging parameters, up to 250 000 actuators and inter-actuator spacing around 500 μm. MOEMS-based devices are promising for the development of a complete generation of new deformable mirrors. Our micro-deformable mirror (MDM) is based on an array of electrostatic actuators with attachments to a continuous mirror on top. The originality of our approach lies in the elaboration of layers made of polymer materials. Mirror layers and active actuators have been demonstrated. Based on the design of this actuator and our polymer process, realization of a complete polymer-MDM has been done using two process flows: the first involves exclusively polymer materials while the second uses SU8 polymer for structural layers and SiO II and sol-gel for sacrificial layers. The latest shows a better capability in order to produce completely released structures. The electrostatic force provides a non-linear actuation, while AO systems are based on linear matrices operations. Then, we have developed a dedicated 14-bit electronics in order to "linearize" the actuation, using a calibration and a sixth-order polynomial fitting strategy. The response is nearly perfect over our 3×3 MDM prototype with a standard deviation of 3.5 nm; the influence function of the central actuator has been measured. First evaluation on the cross non-linarities has also been studied on OKO mirror and a simple look-up table is sufficient for determining the location of each actuator whatever the locations of the neighbor actuators. Electrostatic MDM are particularly well suited for open-loop AO applications.

Anomalous transport in mirror systems

International Nuclear Information System (INIS)

Post, R.F.

1979-01-01

As now being explored for fusion applications confinement systems based on the mirror principle embody two kinds of plasma regimes. These two regimes are: (a) high-beta plasmas, stabilized against MHD and other low frequency plasma instabilities by magnetic-well fields, but characterized by non-Maxwellian ion distributions; (b) near-Maxwellian plasmas, confined electrostatically (as in the tandem mirror) or in a field-reversed region within the mirror cell. Common to both situations are the questions of anomalous transport owing to high frequency instabilities in the non-maxwellian portions of the plasmas. This report will summarize the status of theory and of experimental data bearing on these questions, with particular reference to the high temperature regimes of interest for fusion power

Summary of UCRL pyrotron (mirror machine) program

Energy Technology Data Exchange (ETDEWEB)

Post, R F [Radiation Laboratory, University of California, Livermore, CA (United States)

1958-07-01

Under the sponsorship of the Atomic Energy Commission, work has been going forward at the University of California Radiation Laboratory since 1952 to investigate the application of the so-called 'magnetic mirror' effect to the creation and confinement of a high temperature plasma. This report presents some of the theory of operation of the Mirror Machine, and summarizes the experimental work which has been carried out.

Reduction effect of neutral density on the excitation of turbulent drift waves in a linear magnetized plasma with flow

International Nuclear Information System (INIS)

Saitou, Y.; Yonesu, A.; Shinohara, S.; Ignatenko, M. V.; Kasuya, N.; Kawaguchi, M.; Terasaka, K.; Nishijima, T.; Nagashima, Y.; Kawai, Y.; Yagi, M.; Itoh, S.-I.; Azumi, M.; Itoh, K.

2007-01-01

The importance of reducing the neutral density to reach strong drift wave turbulence is clarified from the results of the extended magnetohydrodynamics and Monte Carlo simulations in a linear magnetized plasma. An upper bound of the neutral density relating to the ion-neutral collision frequency for the excitation of drift wave instability is shown, and the necessary flow velocity to excite this instability is also estimated from the neutral distributions. Measurements of the Mach number and the electron density distributions using Mach probe in the large mirror device (LMD) of Kyushu University [S. Shinohara et al., Plasma Phys. Control. Fusion 37, 1015 (1995)] are reported as well. The obtained results show a controllability of the neutral density and provide the basis for neutral density reduction and a possibility to excite strong drift wave turbulence in the LMD

Chromatic aberrations of two-electrode transaxial mirrors

International Nuclear Information System (INIS)

Bejzina, L.G.; Karetskaya, S.P.

1991-01-01

Second order chromatic aberrations of electrostatic two-electrode transaxial mirrors in case the beam axial trajectory of charged particles is curvilinear are considered. Interrelations between coefficients of linear and angular chromatic aberrations are determined. Values of these coefficients for concave and convex transaxial mirrors with plane electrodes in dependence on potential ratio on electrodes by different onnular clearance radii are presented

Direct torque control via feedback linearization for permanent magnet synchronous motor drives

DEFF Research Database (Denmark)

Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

2012-01-01

The paper describes a direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive that employs feedback linearization and uses sliding-mode and linear controllers. We introduce a new feedback linearization approach that yields a decoupled linear PMSM model with two state...

Design of tandem mirror reactors with thermal barriers

International Nuclear Information System (INIS)

Carlson, G.A.

1980-01-01

End-plug technologies for tandem mirror reactors include high-field superconducting magnets, neutral beam injectors, and gyrotrons for electron cyclotron resonant heating (ECRH). In addition to their normal use for sustenance of the end-plug plasmas, neutral beam injectors are used for ''pumping'' trapped ions from the thermal barrier regions by charge exchange. An extra function of the axially directed pump beams is the removal of thermalized alpha particles from the reactor. The principles of tandem mirror operation with thermal barriers will be demonstrated in the upgrade of the Tandem Mirror Experiment (TMX-U) in 1981 and the tandem configuration of the Mirror fusion Test Facility (MFTF-B) in 1984

Linear relativistic gyrokinetic equation in general magnetically confined plasmas

International Nuclear Information System (INIS)

Tsai, S.T.; Van Dam, J.W.; Chen, L.

1983-08-01

The gyrokinetic formalism for linear electromagnetic waves of arbitrary frequency in general magnetic-field configurations is extended to include full relativistic effects. The derivation employs the small adiabaticity parameter rho/L 0 where rho is the Larmor radius and L 0 the equilibrium scale length. The effects of the plasma and magnetic field inhomogeneities and finite Larmor-radii effects are also contained

Influence of the shear flow on electron cyclotron resonance plasma confinement in an axisymmetric magnetic mirror trap of the electron cyclotron resonance ion source.

Science.gov (United States)

Izotov, I V; Razin, S V; Sidorov, A V; Skalyga, V A; Zorin, V G; Bagryansky, P A; Beklemishev, A D; Prikhodko, V V

2012-02-01

Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap ("vortex" confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of "vortex" confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.

Influence of the shear flow on electron cyclotron resonance plasma confinement in an axisymmetric magnetic mirror trap of the electron cyclotron resonance ion source

International Nuclear Information System (INIS)

Izotov, I. V.; Razin, S. V.; Sidorov, A. V.; Skalyga, V. A.; Zorin, V. G.; Bagryansky, P. A.; Beklemishev, A. D.; Prikhodko, V. V.

2012-01-01

Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap (''vortex'' confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of ''vortex'' confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.

A Revised Piecewise Linear Recursive Convolution FDTD Method for Magnetized Plasmas

International Nuclear Information System (INIS)

Liu Song; Zhong Shuangying; Liu Shaobin

2005-01-01

The piecewise linear recursive convolution (PLRC) finite-different time-domain (FDTD) method improves accuracy over the original recursive convolution (RC) FDTD approach and current density convolution (JEC) but retains their advantages in speed and efficiency. This paper describes a revised piecewise linear recursive convolution PLRC-FDTD formulation for magnetized plasma which incorporates both anisotropy and frequency dispersion at the same time, enabling the transient analysis of magnetized plasma media. The technique is illustrated by numerical simulations of the reflection and transmission coefficients through a magnetized plasma layer. The results show that the revised PLRC-FDTD method has improved the accuracy over the original RC FDTD method and JEC FDTD method

Sensorimotor learning configures the human mirror system.

Science.gov (United States)

Catmur, Caroline; Walsh, Vincent; Heyes, Cecilia

2007-09-04

Cells in the "mirror system" fire not only when an individual performs an action but also when one observes the same action performed by another agent [1-4]. The mirror system, found in premotor and parietal cortices of human and monkey brains, is thought to provide the foundation for social understanding and to enable the development of theory of mind and language [5-9]. However, it is unclear how mirror neurons acquire their mirror properties -- how they derive the information necessary to match observed with executed actions [10]. We address this by showing that it is possible to manipulate the selectivity of the human mirror system, and thereby make it operate as a countermirror system, by giving participants training to perform one action while observing another. Before this training, participants showed event-related muscle-specific responses to transcranial magnetic stimulation over motor cortex during observation of little- and index-finger movements [11-13]. After training, this normal mirror effect was reversed. These results indicate that the mirror properties of the mirror system are neither wholly innate [14] nor fixed once acquired; instead they develop through sensorimotor learning [15, 16]. Our findings indicate that the human mirror system is, to some extent, both a product and a process of social interaction.

Ballooning-mirror instability and internally driven Pc 4--5 wave events

International Nuclear Information System (INIS)

Cheng, C.Z.; Qian, Q.; Takahashi, K.; Lui, A.T.Y.

1994-03-01

A kinetic-MHD field-aligned eigenmode stability analysis of low frequency ballooning-mirror instabilities has been performed for anisotropic pressure plasma sin the magnetosphere. The ballooning mode is mainly a transverse wave driven unstable by pressure gradient in the bad curvature region. The mirror mode with a dominant compressional magnetic field perturbation is excited when the product of plasma beta and pressure anisotropy (P perpendicular /P parallel > 1) is large. From the AMPTE/CCE particle and magnetic field data observed during Pc 4--5 wave events the authors compute the ballooning-mirror instability parameters and perform a correlation study with the theoretical instability threshold. They find that compressional Pc 5 waves approximately satisfy the ballooning-mirror instability condition, and transverse Pc 4--5 waves are probably related to resonant ballooning instabilities with small pressure anisotropy

13th International Conference on Magnetically Levitated Systems and Linear Drives

International Nuclear Information System (INIS)

1993-01-01

This report contains short papers on research being conducted throughout the world on magnetically levitated systems, mainly consisting of trains, and magnetic linear drives. These papers have been index separately elsewhere on the data base

13th International Conference on Magnetically Levitated Systems and Linear Drives

Energy Technology Data Exchange (ETDEWEB)

1993-09-01

This report contains short papers on research being conducted throughout the world on magnetically levitated systems, mainly consisting of trains, and magnetic linear drives. These papers have been index separately elsewhere on the data base.

Pulsed-laser time-resolved thermal mirror technique in low-absorbance homogeneous linear elastic materials.

Science.gov (United States)

Lukasievicz, Gustavo V B; Astrath, Nelson G C; Malacarne, Luis C; Herculano, Leandro S; Zanuto, Vitor S; Baesso, Mauro L; Bialkowski, Stephen E

2013-10-01

A theoretical model for a time-resolved photothermal mirror technique using pulsed-laser excitation was developed for low absorption samples. Analytical solutions to the temperature and thermoelastic deformation equations are found for three characteristic pulse profiles and are compared to finite element analysis methods results for finite samples. An analytical expression for the intensity of the center of a continuous probe laser at the detector plane is derived using the Fresnel diffraction theory, which allows modeling of experimental results. Experiments are performed in optical glasses, and the models are fitted to the data. The parameters of the fit are in good agreement with previous literature data for absorption, thermal diffusion, and thermal expansion of the materials tested. The combined modeling and experimental techniques are shown to be useful for quantitative determination of the physical properties of low absorption homogeneous linear elastic material samples.

Nonlinear mirror mode dynamics: Simulations and modeling

Czech Academy of Sciences Publication Activity Database

Califano, F.; Hellinger, Petr; Kuznetsov, E.; Passot, T.; Sulem, P. L.; Trávníček, Pavel

2008-01-01

Roč. 113, - (2008), A08219/1-A08219/20 ISSN 0148-0227 R&D Projects: GA AV ČR IAA300420702; GA AV ČR IAA300420602 Grant - others:PECS(CZ) 98024 Institutional research plan: CEZ:AV0Z30420517 Keywords : mirror instability * nonlinear evolution * numerical simulations * magnetic holes * mirror structures * kinetic plasma instabilities Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.147, year: 2008

RF-heating and plasma confinement studies in HANBIT mirror device

International Nuclear Information System (INIS)

Kwon, M.; Bak, J.G.; Choh, K.K.

2003-01-01

HANBIT is a magnetic mirror confinement device. Recently, with almost finishing the first campaign for the basic system development, it started the second campaign for the high-temperature plasma confinement physics study in mirror configuration. Here, we introduce briefly the HANBIT device and report initial physics experiments results on RF-plasma heating and confinement in the simple mirror configuration. It appears that the discharge characteristics of HANBIT are quite different from those in other mirror devices, and an explanation is presented to clarify the difference. (author)

Design for an aberration corrected scanning electron microscope using miniature electron mirrors.

Science.gov (United States)

Dohi, Hideto; Kruit, Pieter

2018-06-01

Resolution of scanning electron microscopes (SEMs) is determined by aberrations of the objective lens. It is well known that both spherical and chromatic aberrations can be compensated by placing a 90-degree bending magnet and an electron mirror in the beam path before the objective lens. Nevertheless, this approach has not led to wide use of these aberration correctors, partly because aberrations of the bending magnet can be a serious problem. A mirror corrector with two mirrors placed perpendicularly to the optic axis of an SEM and facing each other is proposed. As a result, only small-angle magnetic deflection is necessary to guide the electron beam around the top mirror to the bottom mirror and around the bottom mirror to the objective lens. The deflection angle, in the order of 50 mrad, is sufficiently small to avoid deflection aberrations. In addition, lateral dispersion at the sample plane can be avoided by making the deflection fields symmetric. Such a corrector system is only possible if the incoming beam can pass the top mirror at a distance in the order of millimeters, without being disturbed by the electric fields of electrodes of the mirror. It is proposed that condition can be satisfied with micro-scale electron optical elements fabricated by using MEMS technology. In the proposed corrector system, the micro-mirrors have to provide the exact negative spherical and chromatic aberrations for correcting the aberration of the objective lens. This exact tuning is accomplished by variable magnification between the micro-mirrors and the objective lens using an additional transfer lens. Extensive optical calculations are reported. Aberrations of the micro-mirrors were analyzed by numerical calculation. Dispersion and aberrations of the deflectors were calculated by using an analytical field model. Combination aberrations caused by the off-axis position of dispersive rays in the mirrors and objective lens were also analyzed. It is concluded that the proposed

PSI-ECRIT(S) a hybrid magnetic system with a mirror ratio of 10 for H-like heavy ion production and trapping

CERN Document Server

Biri, S; Hitz, D

1999-01-01

At the Paul Scherrer Institut ( PSI, Switzerland) an experimental program is started to measure the ground state shift and width of pionic hydrogen. To calibrate the crystal spectrometer X-ray transitions in hydrogen-like heavy ions (e.g. Ar17+) produced by ECR ion sources, are necessary. In PSI a superconducting cyclotron trap magnet originally developed for high energy experiments will be transformed into an ECR Ion Trap (ECRIT). The SC-magnet can deliver more than 4 Tesla magnetic fields with a mirror ratio of 2. A careful calculation showed this mirror ratio can be increased upto 10 and the trap can operate with frequencies between 5 and 20 GHz. To form a closed resonance zone a relatively large open structure (LBL-AECRU-type) NdFeB hexapole will be applied. The first tests will be performed with 6.4 GHz. Later higher frequencies (10 or 14.5 GHz) and the 2-frequency heating (6.4+10, 6.4+14.5 or 10+14.5) are planned to be applied to get enough quantity of H-like heavy ions. Since the main goal of this mach...

Mirror fusion test facility plasma diagnostics system

International Nuclear Information System (INIS)

Thomas, S.R. Jr.; Coffield, F.E.; Davis, G.E.; Felker, B.

1979-01-01

During the past 25 years, experiments with several magnetic mirror machines were performed as part of the Magnetic Fusion Energy (MFE) Program at LLL. The latest MFE experiment, the Mirror Fusion Test Facility (MFTF), builds on the advances of earlier machines in initiating, stabilizing, heating, and sustaining plasmas formed with deuterium. The goals of this machine are to increase ion and electron temperatures and show a corresponding increase in containment time, to test theoretical scaling laws of plasma instabilities with increased physical dimensions, and to sustain high-beta plasmas for times that are long compared to the energy containment time. This paper describes the diagnostic system being developed to characterize these plasma parameters

Trapping of Electron Cloud LLC/Cesrta Quadrupole and Sextupole Magnets

International Nuclear Information System (INIS)

Wang, L.

2011-01-01

The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in CESRTA and ILC quadrupole and sextupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with a long lifetime in a quadrupole and sextupole magnet due to the mirror field trapping mechanism. We study the effects of magnet strength, bunch current, ante-chamber effect, bunch spacing effect and secondary emission yield (SEY) in great detail. The development of an electron cloud in magnets is the main concern where a weak solenoid field is not effective. Quadrupole and sextupole magnets have mirror field configurations which may trap electrons by the mirror field trapping mechanism (2). Fig.1 shows the orbit of a trapped electron in a quadrupole magnet. The electron makes gyration motion (called transverse motion) and also moves along the field line (called longitudinal motion). At the mirror point (middle of the field line), there is a maximum longitudinal energy and minimum transverse energy. When the electron moves away from the mirror point, its longitudinal energy reduces and the transverse energy increases as the magnetic field increases. If the magnetic field is strong enough, the longitudinal energy becomes zero at one point and then the electron is turned back by the strong field. Note that the electrons are trapped in the region near the middle of the field lines. Although all quadrupole and sextupole magnets can trap electrons in principle, the

Theory of ballooning-mirror instabilities for anisotropic pressure plasmas in the magnetosphere

International Nuclear Information System (INIS)

Cheng, C.Z.; Qian, Q.

1993-09-01

This paper deals with a kinetic-MHD eigenmode stability analysis of low frequency ballooning-mirror instabilities for anisotropic pressure plasmas in the magnetosphere. The ballooning mode is a dominant transverse wave driven unstable by pressure gradient in the bad curvature region. The mirror mode with a dominant compressional magnetic field perturbation is excited when the product of plasma beta and pressure anisotropy is large. The field-aligned eigenmode equations take into account the coupling of the transverse and compressional components of the perturbed magnetic field and describe the coupled ballooning-mirror mode. Because the energetic trapped ions precess very rapidly across the rvec B field, their motion becomes very rigid with respect to low frequency MHD perturbations with symmetric structure of parallel perturbed magnetic field δB parallel and electrostatic potential Φ along the north-south ambient magnetic field, and the symmetric ballooning-mirror mode is shown to be stable. On the other hand, the ballooning-mirror mode with antisymmetric δB parallel , and Φ structure along the north-south ambient magnetic field is only weakly influenced by energetic trapped particle kinetic effects due to rapid trapped particle bounce motion and has the lowest instability threshold determined by MHD theory. With large plasma beta (β parallel ≥ O(1)) and pressure anisotropy (P perpendicular /P parallel > 1) at equator the antisymmetric ballooning-mirror mode structures resemble the field-aligned wave structures of the multisatellite observations of a long lasting compressional Pc 5 wave event during November 14--15, 1979 [Takahashi et al.]. The study provides the theoretical basis for identifying the internal excitation mechanism of ULF (Pc 4-5) waves by comparing the plasma stability parameters computed from the satellite particle data with the theoretical values

Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap

CERN Document Server

Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Kurchaninov, L; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S

2012-01-01

Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum (minimum-B) trap formed by superconducting octupole and mirror magnet coils. The trapped antiatoms were detected by rapidly turning off these magnets, thereby eliminating the magnetic minimum and releasing any antiatoms contained in the trap. Once released, these antiatoms quickly hit the trap wall, whereupon the positrons and antiprotons in the antiatoms annihilated. The antiproton annihilations produce easily detected signals; we used these signals to prove that we trapped antihydrogen. However, our technique could be confounded by mirror-trapped antiprotons, which would produce seemingly-identical annihilation signals upon hitting the trap wall. In this paper, we discuss possible sources of mirror-trapped antiprotons and show that antihydrogen and antiprotons can be readily distinguished, often with the aid of applied electric fields, by analyzing the annihilation locations and times. We further discuss the general properties of antipr...

Design and analysis of tubular permanent magnet linear wave generator.

Science.gov (United States)

Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

2014-01-01

Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

Directory of Open Access Journals (Sweden)

Jikai Si

2014-01-01

Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

Science.gov (United States)

Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

2014-01-01

Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388

Numerical studies on the force characteristic of superconducting linear synchronous motor with HTS bulk magnet

Science.gov (United States)

Tang, Junjie; Li, Jing; Li, Xiang; Han, Le

2018-03-01

High temperature superconductor (HTS) bulks have significant potential use in linear motor application act as quasi-permanent magnet to replace traditional magnets. Force characteristic between HTS bulk magnet and traveling magnetic field was investigated with numerical simulation and experimental measurement in this paper. Influences of bulk height and number on the force characteristic were studied by the finite element model considering the nonlinear E-J relationship. Study was also made on addition of a back iron plate to the bulk magnet. Besides, force characteristic of bulk was compared with the permanent magnet results. The small initial decrease of the thrust could be explained by inside superconducting current redistribution. It was found that efficiency of linear motor did not increase by adding more bulk magnets. The bulk magnet will be remagnetized instead of erasing trapped field with the increase of the traveling magnetic field strength. The conclusions are helpful in prediction and design the linear motor with HTS bulk magnet.

Elastoconductivity as a probe of broken mirror symmetries

Energy Technology Data Exchange (ETDEWEB)

Hlobil, Patrik; Maharaj, Akash V.; Hosur, Pavan; Shapiro, M. C.; Fisher, I. R.; Raghu, S.

2015-07-27

We propose the possible detection of broken mirror symmetries in correlated two-dimensional materials by elastotransport measurements. Using linear response theory we calculate the“shear conductivity” Γ x x , x y , defined as the linear change of the longitudinal conductivity σ x x due to a shear strain ε x y . This quantity can only be nonvanishing when in-plane mirror symmetries are broken and we discuss how candidate states in the cuprate pseudogap regime (e.g., various loop current or charge orders) may exhibit a finite shear conductivity. We also provide a realistic experimental protocol for detecting such a response.

Mirror Advanced Reactor Study (MARS)

International Nuclear Information System (INIS)

Logan, B.G.

1983-01-01

Progress in a two year study of a 1200 MWe commercial tandem mirror reactor (MARS - Mirror Advanced Reactor Study) has reached the point where major reactor system technologies are identified. New design features of the magnets, blankets, plug heating systems and direct converter are described. With the innovation of radial drift pumping to maintain low plug density, reactor recirculating power fraction is reduced to 20%. Dominance of radial ion and impurity losses into the halo permits gridless, circular direct converters to be dramatically reduced in size. Comparisons of MARS with the Starfire tokamak design are made

Analysis and Design of Double-sided Air core Linear Servo Motor with Trapezoidal Permanent Magnets

DEFF Research Database (Denmark)

Zhang, Yuqiu; Yang, Zilong; Yu, Minghu

2011-01-01

In order to reduce the thrust ripple of linear servo system, a double-sided air core permanent magnet linear servo motor with trapezoidal shape permanent magnets (TDAPMLSM) is proposed in this paper. An analytical model of the motor for predicting the magnetic field in the air-gap at no...

Hi-speed compact deformable mirror: status, applications, and perspectives

Science.gov (United States)

Rooms, F.; Camet, S.; Curis, J.-F.

2010-02-01

Membrane deformable mirrors based on magnetic actuators have been known for years. State-of-the-art deformable mirrors usually have large strokes but low bandwidth. Furthermore, this bandwidth decreases with the diameter. In this paper, we present the results of a new actuator principle based on magnetic forces allowing high bandwidth (up to a few kHz), very large stroke (>30μm) with a record pitch of 1.5mm. The benefits of this technology will be presented for three applications: astronomy, vision science and microscopy. The parameters of the mirrors have been tuned such that the inter-actuator stroke of the deformable (more than 2.0μm) in order to fit the atmosphere turbulence characteristics. In vision science, efforts have been made to correct both simultaneously the low and high order aberrations (more than 45μm of wavefront correction on astigmatism and focus). Finally, we will demonstrate how we have developed a deformable mirror able to correct spherical aberrations (microscopy). The last part of the article is devoted to give some perspectives about this technology.

Linear spin-wave theory of incommensurably modulated magnets

DEFF Research Database (Denmark)

Ziman, Timothy; Lindgård, Per-Anker

1986-01-01

Calculations of linearized theories of spin dynamics encounter difficulties when applied to incommensurable magnetic phases: lack of translational invariance leads to an infinite coupled system of equations. The authors resolve this for the case of a `single-Q' structure by mapping onto the problem......: at higher frequency there appear bands of response sharply defined in frequency, but broad in momentum transfer; at low frequencies there is a response maximum at the q vector corresponding to the modulation vector. They discuss generalizations necessary for application to rare-earth magnets...

Six-strut arrangements for cartesian movements of mirrors

International Nuclear Information System (INIS)

Noll, T.; Zeschke, Th.; Reichardt, G.; Lammert, H.; Gudat, W.

2001-01-01

At BESSY a new six-strut arrangement for general small travel mirror adjustment mechanisms has been developed. This patented (Patent DE 10042802.5) arrangement allows very simple movements in all six linear and rotational degrees of freedom. The movements of the mirror are simply determined by moving either one drive, or up to three drives by the same amount. The first mirror adjustment systems of this design is successfully in operation since the start of BESSY II. Their performance and reliability is very satisfactory. This contribution will present the concepts

Cosmological Constraints on Mirror Matter Parameters

International Nuclear Information System (INIS)

Wallemacq, Quentin; Ciarcelluti, Paolo

2014-01-01

Up-to-date estimates of the cosmological parameters are presented as a result of numerical simulations of cosmic microwave background and large scale structure, considering a flat Universe in which the dark matter is made entirely or partly of mirror matter, and the primordial perturbations are scalar adiabatic and in linear regime. A statistical analysis using the Markov Chain Monte Carlo method allows to obtain constraints of the cosmological parameters. As a result, we show that a Universe with pure mirror dark matter is statistically equivalent to the case of an admixture with cold dark matter. The upper limits for the ratio of the temperatures of ordinary and mirror sectors are around 0.3 for both the cosmological models, which show the presence of a dominant fraction of mirror matter, 0.06≲Ω_m_i_r_r_o_rh"2≲0.12.

Critical energy in the cyclotron heating of ions in a mirror machine; Energia critica en el calentamiento ciclotronico de los iones en una maquina espejo

Energy Technology Data Exchange (ETDEWEB)

Gutierrez T, C.; Hernandez A, O. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2002-07-01

The problem of heating in the plasma sources where the geometry of the magnetic field forms a magnetic mirror as it is the case of the Ecr sources type, for maintaining the reload, it continues being an actual important problem. There are two methods for the analysis of this problem. The first of these methods is the stochastic mechanism of a particle where it is considered the existence of three characteristic frequencies as the cyclotron frequency, the electromagnetic field frequency and the transit frequency. The second method is that related with the non linear interaction of waves where the collective effects of the particles are the most important. In this work, in the Hamiltonian formalism, the stochastic mechanism in the cyclotron heating is analysed. It is considered the particular case of a plasma source with an external magnetic field, type mirror where a TE{sub 11} electromagnetic wave is injected. The critical energy in the resonance mixing is calculated by the Poincare mapping method. The heterogeneity of the magnetic field is analysed. (Author)

Linear Optical Response of Silicon Nanotubes Under Axial Magnetic Field

Science.gov (United States)

Chegel, Raad; Behzad, Somayeh

2013-01-01

We investigated the optical properties of silicon nanotubes (SiNTs) in the low energy region, E < 0.5 eV, and middle energy region, 1.8 eV < E < 2 eV. The dependence of optical matrix elements and linear susceptibility on radius and magnetic field, in terms of one-dimensional (1-d) wavevector and subband index, is calculated using the tight-binding approximation. It is found that, on increasing the nanotube diameter, the low-energy peaks show red-shift and their intensities are decreased. Also, we found that in the middle energy region all tubes have two distinct peaks, where the energy position of the second peak is approximately constant and independent of the nanotube diameter. Comparing the band structure of these tubes in different magnetic fields, several differences are clearly seen, such as splitting of degenerate bands, creation of additional band-edge states, and bandgap modification. It is found that applying the magnetic field leads to a phase transition in zigzag silicon hexagonal nanotubes (Si h-NTs), unlike in zigzag silicon gear-like nanotubes (Si g-NTs), which remain semiconducting in any magnetic field. We found that the axial magnetic field has two effects on the linear susceptibility spectrum, namely broadening and splitting. The axial magnetic field leads to the creation of a peak with energy less than 0.2 eV in metallic Si h-NTs, whereas in the absence of a magnetic field such a transition is not allowed.

Division of the momentum of electromagnetic waves in linear media into electromagnetic and material parts.

Science.gov (United States)

Saldanha, Pablo L

2010-02-01

It is proposed a natural and consistent division of the momentum of electromagnetic waves in linear, non-dispersive and non-absorptive dielectric and magnetic media into material and electromagnetic parts. The material part is calculated using directly the Lorentz force law and the electromagnetic momentum density has the form epsilon(0)E x B, without an explicit dependence on the properties of the media. The consistency of the treatment is verified through the obtention of a correct momentum balance equation in many examples and showing the compatibility of the division with the Einstein's theory of relativity by the use of a gedanken experiment. An experimental prediction for the radiation pressure on mirrors immersed in linear dielectric and magnetic media is also made.

Design and testing of a coaxial linear magnetic spring with integral linear motor. [for spacecraft energy storage

Science.gov (United States)

Patt, P. J.

1985-01-01

The design of a coaxial linear magnetic spring which incorporates a linear motor to control axial motion and overcome system damping is presented, and the results of static and dynamic tests are reported. The system has nominal stiffness 25,000 N/m and is designed to oscillate a 900-g component over a 4.6-mm stroke in a Stirling-cycle cryogenic refrigerator being developed for long-service (5-10-yr) space applications (Stolfi et al., 1983). Mosaics of 10 radially magnetized high-coercivity SmCO5 segments enclosed in Ti cans are employed, and the device is found to have quality factor 70-100, corresponding to energy-storage efficiency 91-94 percent. Drawings, diagrams, and graphs are provided.

Tandem Mirror Reactor Systems Code (Version I)

International Nuclear Information System (INIS)

Reid, R.L.; Finn, P.A.; Gohar, M.Y.

1985-09-01

A computer code was developed to model a Tandem Mirror Reactor. Ths is the first Tandem Mirror Reactor model to couple, in detail, the highly linked physics, magnetics, and neutronic analysis into a single code. This report describes the code architecture, provides a summary description of the modules comprising the code, and includes an example execution of the Tandem Mirror Reactor Systems Code. Results from this code for two sensitivity studies are also included. These studies are: (1) to determine the impact of center cell plasma radius, length, and ion temperature on reactor cost and performance at constant fusion power; and (2) to determine the impact of reactor power level on cost

Edge diagnostics for tandem mirror machines

International Nuclear Information System (INIS)

Allen, S.L.

1984-01-01

The edge plasma in a tandem mirror machine shields the plasma core from cold neutral gas and impurities. A variety of diagnostics are used to measure the fueling, shielding, and confinement of the edge plasma in both the end plug and central cell regions. Fast ion gauges and residual gas analyzers measure the gas pressure and composition outside of the plasma. An array of Langmuir probes is used to measure the electron density and temperature. Extreme ultraviolet (euv) and visible spectroscopy are used to measure both the impurity and deuterium densities and to estimate the shielding factor for the core plasma. The linear geometry of a tandem mirror also allows direct measurements of the edge plasma by sampling the ions and electrons lost but the ends of the machine. Representative data obtained by these diagnostics during operation of the Tandem Mirror Experiment (TMX) and Tandem Mirror Experiment-Upgrade (TMX-U) experiments are presented. Diagnostics that are currently being developed to diagnose the edge plasma are also discussed

Numerical investigation of multi-beam laser heterodyne measurement with ultra-precision for linear expansion coefficient of metal based on oscillating mirror modulation

Science.gov (United States)

Li, Yan-Chao; Wang, Chun-Hui; Qu, Yang; Gao, Long; Cong, Hai-Fang; Yang, Yan-Ling; Gao, Jie; Wang, Ao-You

2011-01-01

This paper proposes a novel method of multi-beam laser heterodyne measurement for metal linear expansion coefficient. Based on the Doppler effect and heterodyne technology, the information is loaded of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by temperature variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain the value of linear expansion coefficient of metal by the calculation. This novel method is used to simulate measurement for linear expansion coefficient of metal rod under different temperatures by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.4%.

Test of Optimized 120-mm LARP $Nb_{3}S_n$ Quadrupole Coil Using Magnetic Mirror Structure

CERN Document Server

Chlachidze, G; Andreev, N; Anerella, M; Barzi, E; Bossert, R; Caspi, S; Cheng, D; Dietderich, D; Felice, H; Ferracin, P; Ghosh, A; Godeke, A; Hafalia, A R; Kashikhin, V V; Lamm, M; Marchevsky, M; Nobrega, A; Novitski, I; Orris, D; Sabbi, G L; Schmalzle, J; Wanderer, P; Zlobin, A V

2013-01-01

The US LHC accelerator research program (LARP) is developing a new generation of large - aperture high - field quadrupoles based on Nb 3 Sn conductor for the High luminosity upgrade of Large Hadron Collider (HiLumi - LHC). Tests of the first series of 120 - mm aperture HQ coils revealed the necessity for further optimization of the coil design and fabrication process. Modifications in coil design were gradually implemented in two HQ coils previously tested at Fermi National Accelerato r Laboratory (Fermilab) using a magnetic mirror structure (HQM01 and HQM02). This paper describes the construction and test of an HQ mirror model with a coil of optimized design and with an interlayer resistive core in the conductor. The cable for this co il was made of a smaller diameter strand, providing more room for coil expansion during reaction. The 0.8 - mm strand, used in all previous HQ coils was replaced with a 0.778 - mm Nb 3 Sn strand of RRP 108/127 sub - element design. The coil was instrumented with voltage taps, h...

The non-linear growth of the magnetic Rayleigh-Taylor instability

Science.gov (United States)

Carlyle, Jack; Hillier, Andrew

2017-09-01

This work examines the effect of the embedded magnetic field strength on the non-linear development of the magnetic Rayleigh-Taylor instability (RTI) (with a field-aligned interface) in an ideal gas close to the incompressible limit in three dimensions. Numerical experiments are conducted in a domain sufficiently large so as to allow the predicted critical modes to develop in a physically realistic manner. The ratio between gravity, which drives the instability in this case (as well as in several of the corresponding observations), and magnetic field strength is taken up to a ratio which accurately reflects that of observed astrophysical plasma, in order to allow comparison between the results of the simulations and the observational data which served as inspiration for this work. This study finds reduced non-linear growth of the rising bubbles of the RTI for stronger magnetic fields, and that this is directly due to the change in magnetic field strength, rather than the indirect effect of altering characteristic length scales with respect to domain size. By examining the growth of the falling spikes, the growth rate appears to be enhanced for the strongest magnetic field strengths, suggesting that rather than affecting the development of the system as a whole, increased magnetic field strengths in fact introduce an asymmetry to the system. Further investigation of this effect also revealed that the greater this asymmetry, the less efficiently the gravitational energy is released. By better understanding the under-studied regime of such a major phenomenon in astrophysics, deeper explanations for observations may be sought, and this work illustrates that the strength of magnetic fields in astrophysical plasmas influences observed RTI in subtle and complex ways.

Analysis and experimental validation of an HTS linear synchronous propulsion prototype with HTS magnetic suspension

International Nuclear Information System (INIS)

Jin Jianxun; Zheng Luhai; Guo Youguang; Xu Wei; Zhu Jianguo

2011-01-01

An HTS linear synchronous propulsion prototype with an HTSLSM drive is developed. The feasibility of combining an HTSLSM with an HTS magnetic suspension system has been verified. Three different PMGs are studied by ECS method and experiment verification to obtain an optimal one. The prototype has been tested to obtain the performance and thrust characteristics of the HTSLSM. The measurement results benefit the optimal design and control scheme development for an HTSLSM. A high temperature superconducting (HTS) linear propulsion system composed of a single-sided HTS linear synchronous motor (HTSLSM) in its middle and HTS magnetic suspension sub-systems on both sides has been developed. The HTSLSM uses an HTS bulk magnet array on the moving secondary, and the field-trapped characteristics of the HTS bulk using different magnetized methods have been measured and compared to identify their magnetization capability. In order to generate a large levitation force for the system, three different types of permanent magnet guideways (PMGs) have been numerically analyzed and experimentally verified to obtain an optimal PMG. Based on comprehensive experimental prototype tests, the results show that the HTS linear propulsion system can run with stable magnetic suspension having a constant air-gap length, and the thrust characteristics versus the exciting current, working frequency and the air-gap length have also been obtained. This work forms the basis for developing a practical HTS linear propulsion system by using HTS bulks both for propulsion and suspension.

Modelling and measurement of a moving magnet linear compressor performance

International Nuclear Information System (INIS)

Liang, Kun; Stone, Richard; Davies, Gareth; Dadd, Mike; Bailey, Paul

2014-01-01

A novel moving magnet linear compressor with clearance seals and flexure bearings has been designed and constructed. It is suitable for a refrigeration system with a compact heat exchanger, such as would be needed for CPU cooling. The performance of the compressor has been experimentally evaluated with nitrogen and a mathematical model has been developed to evaluate the performance of the linear compressor. The results from the compressor model and the measurements have been compared in terms of cylinder pressure, the ‘P–V’ loop, stroke, mass flow rate and shaft power. The cylinder pressure was not measured directly but was derived from the compressor dynamics and the motor magnetic force characteristics. The comparisons indicate that the compressor model is well validated and can be used to study the performance of this type of compressor, to help with design optimization and the identification of key parameters affecting the system transients. The electrical and thermodynamic losses were also investigated, particularly for the design point (stroke of 13 mm and pressure ratio of 3.0), since a full understanding of these can lead to an increase in compressor efficiency. - Highlights: • Model predictions of the performance of a novel moving magnet linear compressor. • Prototype linear compressor performance measurements using nitrogen. • Reconstruction of P–V loops using a model of the dynamics and electromagnetics. • Close agreement between the model and measurements for the P–V loops. • The design point motor efficiency was 74%, with potential improvements identified

First-wall design limitations for linear magnetic fusion (LMF) reactors

International Nuclear Information System (INIS)

Gryczkowski, G.E.; Krakowski, R.A.; Steinhauer, L.C.; Zumdieck, J.

1978-01-01

One approach to the endloss problem in linear magnetic fusion (LMF) uses high magnetic field to reduce the required confinement time. This approach is limited by magnet stresses and bremsstrahlung heating of the first wall; the first-wall thermal-pulsing issue is addressed. Pertinent thermophysical parameters are developed in the context of high-field LMF to identify promising first-wall materials, and thermal fatigue experiments relevant to LMF first walls are reviewed. High-flux first-wall concepts are described which include both solid and evaporating first-wall configurations

LTPF: a linear theta-pinch neutron source

International Nuclear Information System (INIS)

Ellis, W.R.

1975-07-01

The linear theta pinch is optimized with respect to maximum neutron current on a sample located between the discharge tube and the compression coil wall. Emphasis throughout is placed on physics and technology considerations which govern the choice of parameters. Technological demands are (hopefully) kept to a minimum. Two ''point designs'' are developed which are distinguished by their compressional magnetic field (i.e., coil current) wave-forms: one is sinusoidal and continuous, the other trapezoidal and pulsed intermittently. Both point designs give an average neutron current of approximately 5 x 10 13 n/cm 2 /s. Both devices are characterized by short lengths (approximately 1 m), rapid cycling (2 to 30 kHz), and magnetic mirrors (2 to 5:1) at the ends. A crucial item is the power supply, which is discussed in detail. (U.S.)

Field-reversed mirror reactor

International Nuclear Information System (INIS)

Carlson, G.A.

1978-01-01

The reactor design is a multicell arrangement wherein a series of field-reversed plasma layers are arranged along the axis of a long superconducting solenoid which provides the background magnetic field. Normal copper mirror coils and Ioffe bars placed at the first wall radius provide shallow axial and radial magnetic wells for each plasma layer. Each of 11 plasma layers requires the injection of 3.6 MW of 200 keV deuterium and tritium and produces 20 MW of fusion power. The reactor has a net electric output of 74 MWe and an estimated direct capital cost of $1200/kWe

Linear stability analysis of a levitated nanomagnet in a static magnetic field: Quantum spin stabilized magnetic levitation

Science.gov (United States)

Rusconi, C. C.; Pöchhacker, V.; Cirac, J. I.; Romero-Isart, O.

2017-10-01

We theoretically study the levitation of a single magnetic domain nanosphere in an external static magnetic field. We show that, apart from the stability provided by the mechanical rotation of the nanomagnet (as in the classical Levitron), the quantum spin origin of its magnetization provides two additional mechanisms to stably levitate the system. Despite the Earnshaw theorem, such stable phases are present even in the absence of mechanical rotation. For large magnetic fields, the Larmor precession of the quantum magnetic moment stabilizes the system in full analogy with magnetic trapping of a neutral atom. For low magnetic fields, the magnetic anisotropy stabilizes the system via the Einstein-de Haas effect. These results are obtained with a linear stability analysis of a single magnetic domain rigid nanosphere with uniaxial anisotropy in a Ioffe-Pritchard magnetic field.

Mirror reactor studies

International Nuclear Information System (INIS)

Moir, R.W.; Barr, W.L.; Bender, D.J.

1977-01-01

Design studies of a fusion mirror reactor, a fusion-fission mirror reactor, and two small mirror reactors are summarized. The fusion reactor uses 150-keV neutral-beam injectors based on the acceleration of negative ions. The injectors provide over 1 GW of continuous power at an efficiency greater than 80%. The fusion reactor has three-stage, modularized, Venetian blind, plasma direct converter with a predicted efficiency of 59% and a new concept for removal of the lune-shaped blanket: a crane is brought between the two halves of the Yin-Yang magnet, which are separated by a float. The design has desirable features such as steady-state operation, minimal impurity problems, and low first-wall thermal stress. The major disadvantage is low Q resulting in high re-circulating power and hence high cost of electrical power. However, the direct capital cost per unit of gross electrical power is reasonable [$1000/kW(e)]. By contrast, the fusion-fission reactor design is not penalized by re-circulating power and uses relatively near-term fusion technology being developed for the fusion power program. New results are presented on the Th- 233 U and the U- 239 Pu fuel cycles. The purpose of this hybrid is fuel production, with projected costs at $55/g of Pu or $127/g of 233 U. Blanket and cooling system designs, including an emergency cooling system, by General Atomic Company, lead us to the opinion that the reactor can meet expected safety standards for licensing. The smallest mirror reactor having only a shield between the plasma and the coil is the 4.2-m long fusion engineering research facility (FERF) designed for material irradiation. The smallest mirror reactor having both a blanket and shield is the 7.5-m long experimental power reactor (EPR), which has both a fusion and a fusion-fission version. (author)

Mirror boxes and mirror mounts for photophysics beamline

International Nuclear Information System (INIS)

Raja Rao, P.M.; Raja Sekhar, B.N.; Das, N.C.; Khan, H.A.; Bhattacharya, S.S.; Roy, A.P.

1996-01-01

Photophysics beamline makes use of one metre Seya-Namioka monochromator and two toroidal mirrors in its fore optics. The first toroidal mirror (pre mirror) focuses light originating from the tangent point of the storage ring onto the entrance slit of the monochromator and second toroidal mirror (post mirror) collects light from the exit slit of the monochromator and focuses light onto the sample placed at a distance of about one metre away from the 2nd mirror. To steer light through monochromator and to focus it on the sample of 1mm x 1mm size require precision rotational and translational motion of the mirrors and this has been achieved with the help of precision mirror mounts. Since Indus-1 operates at pressures less than 10 -9 m.bar, the mirror mounts should be manipulated under similar ultra high vacuum conditions. Considering these requirements, two mirror boxes and two mirror mounts have been designed and fabricated. The coarse movements to the mirrors are imparted from outside the mirror chamber with the help of x-y tables and precision movements to the mirrors are achieved with the help of mirror mounts. The UHV compatibility and performance of the mirror mounts connected to mirror boxes under ultra high vacuum condition is evaluated. The details of the design, fabrication and performance evaluation are discussed in this report. 5 refs., 9 figs., 1 tab

Quasi-linear landau kinetic equations for magnetized plasmas: compact propagator formalism, rotation matrices and interaction

International Nuclear Information System (INIS)

Misguich, J.H.

2004-04-01

As a first step toward a nonlinear renormalized description of turbulence phenomena in magnetized plasmas, the lowest order quasi-linear description is presented here from a unified point of view for collisionless as well as for collisional plasmas in a constant magnetic field. The quasi-linear approximation is applied to a general kinetic equation obtained previously from the Klimontovich exact equation, by means of a generalised Dupree-Weinstock method. The so-obtained quasi-linear description of electromagnetic turbulence in a magnetoplasma is applied to three separate physical cases: -) weak electrostatic turbulence, -) purely magnetic field fluctuations (the classical quasi-linear results are obtained for cosmic ray diffusion in the 'slab model' of magnetostatic turbulence in the solar wind), and -) collisional kinetic equations of magnetized plasmas. This mathematical technique has allowed us to derive basic kinetic equations for turbulent plasmas and collisional plasmas, respectively in the quasi-linear and Landau approximation. In presence of a magnetic field we have shown that the systematic use of rotation matrices describing the helical particle motion allows for a much more compact derivation than usually performed. Moreover, from the formal analogy between turbulent and collisional plasmas, the results derived here in detail for the turbulent plasmas, can be immediately translated to obtain explicit results for the Landau kinetic equation

Quasi-linear landau kinetic equations for magnetized plasmas: compact propagator formalism, rotation matrices and interaction

Energy Technology Data Exchange (ETDEWEB)

Misguich, J.H

2004-04-01

As a first step toward a nonlinear renormalized description of turbulence phenomena in magnetized plasmas, the lowest order quasi-linear description is presented here from a unified point of view for collisionless as well as for collisional plasmas in a constant magnetic field. The quasi-linear approximation is applied to a general kinetic equation obtained previously from the Klimontovich exact equation, by means of a generalised Dupree-Weinstock method. The so-obtained quasi-linear description of electromagnetic turbulence in a magnetoplasma is applied to three separate physical cases: -) weak electrostatic turbulence, -) purely magnetic field fluctuations (the classical quasi-linear results are obtained for cosmic ray diffusion in the 'slab model' of magnetostatic turbulence in the solar wind), and -) collisional kinetic equations of magnetized plasmas. This mathematical technique has allowed us to derive basic kinetic equations for turbulent plasmas and collisional plasmas, respectively in the quasi-linear and Landau approximation. In presence of a magnetic field we have shown that the systematic use of rotation matrices describing the helical particle motion allows for a much more compact derivation than usually performed. Moreover, from the formal analogy between turbulent and collisional plasmas, the results derived here in detail for the turbulent plasmas, can be immediately translated to obtain explicit results for the Landau kinetic equation.

Integrated fiber-mirror ion trap for strong ion-cavity coupling

International Nuclear Information System (INIS)

Brandstätter, B.; Schüppert, K.; Casabone, B.; Friebe, K.; Stute, A.; Northup, T. E.; McClung, A.; Schmidt, P. O.; Deutsch, C.; Reichel, J.; Blatt, R.

2013-01-01

We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvature and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate

Long-trace profiler for neutron focusing mirrors

International Nuclear Information System (INIS)

Puzyrev, Yevgeniy S.; Ice, Gene E.; Takacs, Peter Z.

2009-01-01

A long-trace profiler (LTP) optimized for measuring the shape of large neutron supermirrors has been designed and built. This LTP can measure 1.6 m long mirrors in both vertically and horizontally deflecting geometries, which is essential to achieve best performance from bendable mirrors. The LTP suppresses the influence of angular deviations of the linear-stage carriage during translation with a pentaprism and a cylindrical lens. The stationary optical head and the carriage-mounted pentaprism are precisely aligned to rotate about the optical axis between the two components. This feature allows measurements to be made on mirrors mounted vertically, horizontally or at any angle in between. The LTP software allows for rapid optimization of parameters for dynamically bent elliptical mirrors. Here we describe the motivation for the LTP, the design, and a first application of the LTP to study the effect of gravity on a bent microfocusing neutron supermirror.

Influence of magnetic flutter on tearing growth in linear and nonlinear theory

Science.gov (United States)

Kreifels, L.; Hornsby, W. A.; Weikl, A.; Peeters, A. G.

2018-06-01

Recent simulations of tearing modes in turbulent regimes show an unexpected enhancement in the growth rate. In this paper the effect is investigated analytically. The enhancement is linked to the influence of turbulent magnetic flutter, which is modelled by diffusion terms in magnetohydrodynamics (MHD) momentum balance and Ohm’s law. Expressions for the linear growth rate as well as the island width in nonlinear theory for small amplitudes are derived. The results indicate an enhanced linear growth rate and a larger linear layer width compared with resistive MHD. Also the island width in the nonlinear regime grows faster in the diffusive model. These observations correspond well to simulations in which the effect of turbulence on the magnetic island width and tearing mode growth is analyzed.

Study of ICRF wave propagation and plasma coupling efficiency in a linear magnetic mirror device

International Nuclear Information System (INIS)

Peng, S.Y.

1991-07-01

Ion Cyclotron Range of Frequency (ICRF) wave propagation in an inhomogeneous axial magnetic field in a cylindrical plasma-vacuum system has historically been inadequately modelled. Previous works either sacrifice the cylindrical geometry in favor of a simpler slab geometry, concentrate on the resonance region, use a single mode to represent the entire field structure, or examine only radial propagation. This thesis performs both analytical and computational studies to model the ICRF wave-plasma coupling and propagation problem. Experimental analysis is also conducted to compare experimental results with theoretical predictions. Both theoretical as well as experimental analysis are undertaken as part of the thesis. The theoretical studies simulate the propagation of ICRF waves in an axially inhomogeneous magnetic field and in cylindrical geometry. Two theoretical analysis are undertaken - an analytical study and a computational study. The analytical study treats the inhomogeneous magnetic field by transforming the (r,z) coordinate into another coordinate system (ρ,ξ) that allows the solution of the fields with much simpler boundaries. The plasma fields are then Fourier transformed into two coupled convolution-integral equations which are then differenced and solved for both the perpendicular mode number α as well as the complete EM fields. The computational study involves a multiple eigenmode computational analysis of the fields that exist within the plasma-vacuum system. The inhomogeneous axial field is treated by dividing the geometry into a series of transverse axial slices and using a constant dielectric tensor in each individual slice. The slices are then connected by longitudinal boundary conditions

Mirroring

DEFF Research Database (Denmark)

Wegener, Charlotte; Wegener, Gregers

2016-01-01

and metaphorical value of mirroring for creativity theory across two different research fields — neuroscience and learning. We engage in a mutual (possibly creative) exploration of mirroring from ‘mirror neurons’ to mirroring in social learning theory. One of the most fascinating aspects of mirroring...... as a neurobiological and as a learning phenomenon is that it points to the embodied and unconscious aspects of social interaction. Thus, mirroring should not be reduced to the non-creative, mechanical repetition of the original, outstanding creativity. To mirror is a human capability built into our capacity to create......Most definitions of creativity emphasise originality. The creative product is recognised as distinct from other products and the creative person as someone who stands out from the crowd. What tend to be overlooked are acts of mirroring as a crucial element of the creative process. The human ability...

TMX magnets: mechanical design

International Nuclear Information System (INIS)

Hinkle, R.E.; Harvey, A.R.; Calderon, M.O.; Chargin, A.K.; Chen, F.F.K.; Denhoy, B.S.; Horvath, J.A.; Reed, J.R.; Waugh, A.F.

1977-01-01

The Tandem Mirror Experiment (TMX) system, part of the Lawrence Livermore Laboratory magnetic mirror program incorporates in its design various types of coils or magnets. This paper describes the physical construction of each coil within the system as well as the structural design required for their support and installation

Improvement of the dynamic performance of an AC linear permanent magnet machine

NARCIS (Netherlands)

Jansen, J.W.; Lomonova, E.; Vandenput, A.J.A.; Compter, J.C.; Verweij, A.H.

2003-01-01

This paper discusses the controller design and test approaches leading to the performance improvement of a brushless 3-phase AC synchronous permanent magnet linear machine. The feasible controller design concept for the linear machine is presented and further implemented in Simulink and dSPACE. Two

Computation of magnetic field in DC brushless linear motors built with NdFeB magnets

International Nuclear Information System (INIS)

Basak, A.; Shirkoohi, G.H.

1990-01-01

A software package based on finite element technique has been used to compute three-dimensional magnetic fields and static forces developed in brushless d.c. linear motors. As the field flux-source two different types of permanent magnets, one of them being the high energy neodymium- iron-boron type, has been used in computer models. Motors with the same specifications as the computer models were built and experimental results obtained from them are compared with the computed results

Plasma cleaning of ITER edge Thomson scattering mock-up mirror in the EAST tokamak

Science.gov (United States)

Yan, Rong; Moser, Lucas; Wang, Baoguo; Peng, Jiao; Vorpahl, Christian; Leipold, Frank; Reichle, Roger; Ding, Rui; Chen, Junling; Mu, Lei; Steiner, Roland; Meyer, Ernst; Zhao, Mingzhong; Wu, Jinhua; Marot, Laurent

2018-02-01

First mirrors are the key element of all optical and laser diagnostics in ITER. Facing the plasma directly, the surface of the first mirrors could be sputtered by energetic particles or deposited with contaminants eroded from the first wall (tungsten and beryllium), which would result in the degradation of the reflectivity. The impurity deposits emphasize the necessity of the first mirror in situ cleaning for ITER. The mock-up first mirror system for ITER edge Thomson scattering diagnostics has been cleaned in EAST for the first time in a tokamak using radio frequency capacitively coupled plasma. The cleaning properties, namely the removal of contaminants and homogeneity of cleaning were investigated with molybdenum mirror insets (25 mm diameter) located at five positions over the mock-up plate (center to edge) on which 10 nm of aluminum oxide, used as beryllium proxy, were deposited. The cleaning efficiency was evaluated using energy dispersive x-ray spectroscopy, reflectivity measurements and x-ray photoelectron spectroscopy. Using argon or neon plasma without magnetic field in the laboratory and with a 1.7 T magnetic field in the EAST tokamak, the aluminum oxide films were homogeneously removed. The full recovery of the mirrors’ reflectivity was attained after cleaning in EAST with the magnetic field, and the cleaning efficiency was about 40 times higher than that without the magnetic field. All these results are promising for the plasma cleaning baseline scenario of ITER.

Analysis and manipulation of the induced changes in the state of polarization by mirror scanners.

Science.gov (United States)

Petrova-Mayor, Anna; Knudsen, Sarah

2017-05-20

The induced polarization effects of metal-coated mirrors were studied in the configurations of one- and two-mirror lidar scanners as a function of azimuth and elevation angles. The theoretical results were verified experimentally for three types of mirrors (custom enhanced gold, off-the-shelf protected gold, and protected aluminum). A method was devised and tested to maintain a desired polarization state (linear or circular) of the transmit beam for all pointing directions by means of rotating wave plates in the transmit and detection paths. Alternatively, the mirror coating can be optimized to preserve the linear polarization state of the transmitted beam. The compensation methods will enable ground-based scanning lidars to produce absolutely calibrated depolarization measurements.

Numerical investigation of multi-beam laser heterodyne measurement with ultra-precision for linear expansion coefficient of metal based on oscillating mirror modulation

International Nuclear Information System (INIS)

Li Yan-Chao; Wang Chun-Hui; Qu Yang; Gao Long; Cong Hai-Fang; Yang Yan-Ling; Gao Jie; Wang Ao-You

2011-01-01

This paper proposes a novel method of multi-beam laser heterodyne measurement for metal linear expansion coefficient. Based on the Doppler effect and heterodyne technology, the information is loaded of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by temperature variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain the value of linear expansion coefficient of metal by the calculation. This novel method is used to simulate measurement for linear expansion coefficient of metal rod under different temperatures by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.4%. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider.

CERN Document Server

Spencer, C M

2002-01-01

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0 -20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype. See High Reliability Prototype Quadrupole for the Next Linear Collider by C.E Rago, C.M SPENC...

Numerical solutions of ICRF fields in axisymmetric mirrors

International Nuclear Information System (INIS)

Phillips, M.W.

1985-01-01

The results of a new numerical code called GARFIELD (Grumman Aerospace Rf Field code) that calculates ICRF Fields in axisymmetric mirror geometry (such as the central cell of a tandem mirror or an RF test stand) are presented. The code solves the electromagnetic wave equation using a cold plasma dispersion relation with a small collision frequency to simulate absorption. The purpose of the calculation is to examine how ICRF wave structure and propagation is effected by the axial variation of the magnetic field in a mirror for various antenna designs. In the code the wave equation is solved in flux coordinates using a finite element method. This should allow more complex dielectric tensors to be modeled in the future. The resulting matrix is solved iteratively, to maximize the allowable size of the spatial grid. Results for a typical antenna array in a simple mirror will be shown

Mirror, mirror on the wall

CERN Multimedia

2005-01-01

RICH 2, one of the two Ring Imaging Cherenkov detectors of the LHCb experiment, is being prepared to join the other detector elements ready for the first proton-proton collisions at LHC. The mirrors of the RICH2 detector are meticulously assembled in a clean room.In a large dark room, men in white move around an immense structure some 7 metres high, 10 metres wide and nearly 2.5 metres deep. Apparently effortlessly, they are installing the two large high-precision spherical mirrors. These mirrors will focus Cherenkov light, created by the charged particles that will traverse this detector, onto the photon detectors. Each spherical mirror wall is made up of facets like a fly's eye. Twenty-eight individual thin glass mirrors will all point to the same point in space to within a few micro-radians. The development of these mirrors has been technically demanding : Ideally they should be massless, sturdy, precise and have high reflectivity. In practice, though not massless, they are made from a mere 6 mm thin gl...

DC and AC linear magnetic field sensor based on glass coated amorphous microwires with Giant Magnetoimpedance

International Nuclear Information System (INIS)

García-Chocano, Víctor Manuel; García-Miquel, Héctor

2015-01-01

Giant Magnetoimpedance (GMI) effect has been studied in amorphous glass-coated microwires of composition (Fe 6 Co 94 ) 72.5 Si 12.5 B 15 . The impedance of a 1.5 cm length sample has been characterized by using constant AC currents in the range of 400 µA–4 mA at frequencies from 7 to 15 MHz and DC magnetic fields from −900 to 900 A/m. Double peak responses have been obtained, showing GMI ratios up to 107%. A linear magnetic field sensor for DC and AC field has been designed, using two microwires connected in series with a magnetic bias of 400 A/m with opposite direction in each microwire in order to obtain a linear response from ±70 (A/m) rms for AC magnetic field, and ±100 A/m for DC magnetic field. A closed loop feedback circuit has been implemented to extend the linear range to ±1 kA/m for DC magnetic field. - Highlights: • Giant Magneto Impedance phenomenon has been studied in amorphous microwires. • A combination of two microwires with a bias field has been developed to get a linear response. • An electronic circuit has been developed to obtain a sensor with a linear response. • A feedback coil have been added to increase the measurable range of the sensor

Reconnection Scaling Experiment (RSX): Magnetic Reconnection in Linear Geometry

Science.gov (United States)

Intrator, T.; Sovinec, C.; Begay, D.; Wurden, G.; Furno, I.; Werley, C.; Fisher, M.; Vermare, L.; Fienup, W.

2001-10-01

The linear Reconnection Scaling Experiment (RSX) at LANL is a new experiment that can create MHD relevant plasmas to look at the physics of magnetic reconnection. This experiment can scale many relevant parameters because the guns that generate the plasma and current channels do not depend on equilibrium or force balance for startup. We describe the experiment and initial electrostatic and magnetic probe data. Two parallel current channels sweep down a long plasma column and probe data accumulated over many shots gives 3D movies of magnetic reconnection. Our first data tries to define an operating regime free from kink instabilities that might otherwise confuse the data and shot repeatability. We compare this with MHD 2 fluid NIMROD simulations of the single current channel kink stability boundary for a variety of experimental conditions.

Helium temperature measurements in a hot filament magnetic mirror plasma using high resolution Doppler spectroscopy

Science.gov (United States)

Knott, S.; McCarthy, P. J.; Ruth, A. A.

2016-09-01

Langmuir probe and spectroscopic diagnostics are used to routinely measure electron temperature and density over a wide operating range in a reconfigured Double Plasma device at University College Cork, Ireland. The helium plasma, generated through thermionic emission from a negatively biased tungsten filament, is confined by an axisymmetric magnetic mirror configuration using two stacks of NdFeB permanent magnets, each of length 20 cm and diameter 3 cm placed just outside the 15 mm water cooling jacket enclosing a cylindrical vacuum vessel of internal diameter 25 cm. Plasma light is analysed using a Fourier Transform-type Bruker spectrometer with a highest achievable resolution of 0.08 cm-1 . In the present work, the conventional assumption of room temperature ions in the analysis of Langmuir probe data from low temperature plasmas is examined critically using Doppler spectroscopy of the 468.6 nm He II line. Results for ion temperatures obtained from spectroscopic data for a variety of engineering parameters (discharge voltage, gas pressure and plasma current) will be presented.

General methods for determining the linear stability of coronal magnetic fields

Science.gov (United States)

Craig, I. J. D.; Sneyd, A. D.; Mcclymont, A. N.

1988-01-01

A time integration of a linearized plasma equation of motion has been performed to calculate the ideal linear stability of arbitrary three-dimensional magnetic fields. The convergence rates of the explicit and implicit power methods employed are speeded up by using sequences of cyclic shifts. Growth rates are obtained for Gold-Hoyle force-free equilibria, and the corkscrew-kink instability is found to be very weak.

Mirror-Image Equivalence and Interhemispheric Mirror-Image Reversal.

Science.gov (United States)

Corballis, Michael C

2018-01-01

Mirror-image confusions are common, especially in children and in some cases of neurological impairment. They can be a special impediment in activities such as reading and writing directional scripts, where mirror-image patterns (such as b and d ) must be distinguished. Treating mirror images as equivalent, though, can also be adaptive in the natural world, which carries no systematic left-right bias and where the same object or event can appear in opposite viewpoints. Mirror-image equivalence and confusion are natural consequences of a bilaterally symmetrical brain. In the course of learning, mirror-image equivalence may be established through a process of symmetrization, achieved through homotopic interhemispheric exchange in the formation of memory circuits. Such circuits would not distinguish between mirror images. Learning to discriminate mirror-image discriminations may depend either on existing brain asymmetries, or on extensive learning overriding the symmetrization process. The balance between mirror-image equivalence and mirror-image discrimination may nevertheless be precarious, with spontaneous confusions or reversals, such as mirror writing, sometimes appearing naturally or as a manifestation of conditions like dyslexia.

Mirror-Image Equivalence and Interhemispheric Mirror-Image Reversal

Directory of Open Access Journals (Sweden)

Michael C. Corballis

2018-04-01

Full Text Available Mirror-image confusions are common, especially in children and in some cases of neurological impairment. They can be a special impediment in activities such as reading and writing directional scripts, where mirror-image patterns (such as b and d must be distinguished. Treating mirror images as equivalent, though, can also be adaptive in the natural world, which carries no systematic left-right bias and where the same object or event can appear in opposite viewpoints. Mirror-image equivalence and confusion are natural consequences of a bilaterally symmetrical brain. In the course of learning, mirror-image equivalence may be established through a process of symmetrization, achieved through homotopic interhemispheric exchange in the formation of memory circuits. Such circuits would not distinguish between mirror images. Learning to discriminate mirror-image discriminations may depend either on existing brain asymmetries, or on extensive learning overriding the symmetrization process. The balance between mirror-image equivalence and mirror-image discrimination may nevertheless be precarious, with spontaneous confusions or reversals, such as mirror writing, sometimes appearing naturally or as a manifestation of conditions like dyslexia.

Proton transport model in the ionosphere. 2. Influence of magnetic mirroring and collisions on the angular redistribution in a proton beam

Directory of Open Access Journals (Sweden)

M. Galand

1998-10-01

Full Text Available We investigate the influence of magnetic mirroring and elastic and inelastic scattering on the angular redistribution in a proton/hydrogen beam by using a transport code in comparison with observations. H-emission Doppler profiles viewed in the magnetic zenith exhibit a red-shifted component which is indicative of upward fluxes. In order to determine the origin of this red shift, we evaluate the influence of two angular redistribution sources which are included in our proton/hydrogen transport model. Even though it generates an upward flux, the redistribution due to magnetic mirroring effect is not sufficient to explain the red shift. On the other hand, the collisional angular scattering induces a much more significant red shift in the lower atmosphere. The red shift due to collisions is produced  by <1 -keV protons and is so small as to require an instrumental bandwidth <0.2 nm. This explains the absence of measured upward proton/hydrogen fluxes in the Proton I rocket data because no useable data concerning protons <1 keV are available. At the same time, our model agrees with measured ground-based H-emission Doppler profiles and suggests that previously reported red shift observations were due mostly to instrumental bandwidth broadening of the profile. Our results suggest that Doppler profile measurements with higher spectral resolution may enable us to quantify better the angular scattering in proton aurora.Key words. Auroral ionosphere · Particle precipitation

Lexan Linear Shaped Charge Holder with Magnets and Backing Plate

Science.gov (United States)

Maples, Matthew W.; Dutton, Maureen L.; Hacker, Scott C.; Dean, Richard J.; Kidd, Nicholas; Long, Chris; Hicks, Robert C.

2013-01-01

A method was developed for cutting a fabric structural member in an inflatable module, without damaging the internal structure of the module, using linear shaped charge. Lexan and magnets are used in a charge holder to precisely position the linear shaped charge over the desired cut area. Two types of charge holders have been designed, each with its own backing plate. One holder cuts fabric straps in the vertical configuration, and the other charge holder cuts fabric straps in the horizontal configuration.

Mirror Neurons and Mirror-Touch Synesthesia.

Science.gov (United States)

Linkovski, Omer; Katzin, Naama; Salti, Moti

2016-05-30

Since mirror neurons were introduced to the neuroscientific community more than 20 years ago, they have become an elegant and intuitive account for different cognitive mechanisms (e.g., empathy, goal understanding) and conditions (e.g., autism spectrum disorders). Recently, mirror neurons were suggested to be the mechanism underlying a specific type of synesthesia. Mirror-touch synesthesia is a phenomenon in which individuals experience somatosensory sensations when seeing someone else being touched. Appealing as it is, careful delineation is required when applying this mechanism. Using the mirror-touch synesthesia case, we put forward theoretical and methodological issues that should be addressed before relying on the mirror-neurons account. © The Author(s) 2016.

TBA-like integral equations from quantized mirror curves

Energy Technology Data Exchange (ETDEWEB)

Okuyama, Kazumi [Department of Physics, Shinshu University,Matsumoto 390-8621 (Japan); Zakany, Szabolcs [Département de Physique Théorique, Université de Genève,Genève, CH-1211 (Switzerland)

2016-03-15

Quantizing the mirror curve of certain toric Calabi-Yau (CY) three-folds leads to a family of trace class operators. The resolvent function of these operators is known to encode topological data of the CY. In this paper, we show that in certain cases, this resolvent function satisfies a system of non-linear integral equations whose structure is very similar to the Thermodynamic Bethe Ansatz (TBA) systems. This can be used to compute spectral traces, both exactly and as a semiclassical expansion. As a main example, we consider the system related to the quantized mirror curve of local ℙ{sup 2}. According to a recent proposal, the traces of this operator are determined by the refined BPS indices of the underlying CY. We use our non-linear integral equations to test that proposal.

TBA-like integral equations from quantized mirror curves

Science.gov (United States)

Okuyama, Kazumi; Zakany, Szabolcs

2016-03-01

Quantizing the mirror curve of certain toric Calabi-Yau (CY) three-folds leads to a family of trace class operators. The resolvent function of these operators is known to encode topological data of the CY. In this paper, we show that in certain cases, this resolvent function satisfies a system of non-linear integral equations whose structure is very similar to the Thermodynamic Bethe Ansatz (TBA) systems. This can be used to compute spectral traces, both exactly and as a semiclassical expansion. As a main example, we consider the system related to the quantized mirror curve of local P2. According to a recent proposal, the traces of this operator are determined by the refined BPS indices of the underlying CY. We use our non-linear integral equations to test that proposal.

MHD-Stabilization of Axisymmetric Mirror Systems Using Pulsed ECRH

International Nuclear Information System (INIS)

Post, R.F.

2010-01-01

This paper, part of a continuing study of means for the stabilization of MHD interchange modes in axisymmertric mirror-based plasma confinement systems, is aimed at a preliminary look at a technique that would employ a train of plasma pressure pulses produced by ECRH to accomplish the stabilization. The purpose of using sequentially pulsed ECRH rather than continuous-wave ECRH is to facilitate the localization of the heated-electron plasma pulses in regions of the magnetic field with a strong positive field-line curvature, e. g. in the 'expander' region of the mirror magnetic field, outside the outermost mirror, or in other regions of the field with positive field-line curvature. The technique proposed, of the class known as 'dynamic stabilization,' relies on the time-averaged effect of plasma pressure pulses generated in regions of positive field-line curvature to overcome the destabilizing effect of plasma pressure in regions of negative field-line curvature within the confinement region. As will also be discussed in the paper, the plasma pulses, when produced in regions of the confining having a negative gradient, create transient electric potentials of ambipolar origin, an effect that was studied in 1964 in The PLEIDE experiment in France. These electric fields preserve the localization of the hot-electron plasma pulses for a time determined by ion inertia. It is suggested that it may be possible to use this result of pulsed ECRH not only to help to stabilize the plasma but also to help plug mirror losses in a manner similar to that employed in the Tandem Mirror.

Manufacturing the MFTF magnet

International Nuclear Information System (INIS)

Dalder, E.N.C.; Hinkle, R.E.; Hodges, A.J.

1980-01-01

The Mirror Fusion Test Facility (MFTF) is a large mirror program experiment for magnetic fusion energy. It will combine and extend the near-classical plasma confinement achieved in 2XIIB with advanced neutral-beam and magnet technologies. The product of ion density and confinement time will be improved more than an order of magnitude, while the superconducting magnet weight will be extrapolated from 15 tons in Baseball II to 375 tons in MFTF. Recent reactor studies show that the MFTF will traverse much of the distance in magnet technology towards the reactor regime

Comment on the drift mirror instability

Czech Academy of Sciences Publication Activity Database

Hellinger, Petr

2008-01-01

Roč. 15, č. 5 (2008), 054502/1-054502/2 ISSN 1070-664X R&D Projects: GA AV ČR IAA300420702 Institutional research plan: CEZ:AV0Z30420517 Keywords : drift mirror instability * linear theory Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.427, year: 2008

Cyclotron heating rate in a parabolic mirror

International Nuclear Information System (INIS)

Smith, P.K.

1984-01-01

Cyclotron resonance heating rates are found for a parabolic magnetic mirror. The equation of motion for perpendicular velocity is solved, including the radial magnetic field terms neglected in earlier papers. The expression for heating rate involves an infinite series of Anger's and Weber's functions, compared with a single term of the unrevised expression. The new results show an increase of heating rate compared with previous results. A simple expression is given for the ratio of the heating rates. (author)

Force measurements on a shielded coreless linear permanent magnet motor

NARCIS (Netherlands)

Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.A.

2014-01-01

This paper compares force measurements on a shielded coreless linear permanent magnet motor with 2-D models. A 2-D semianalytical modeling method is applied, which is based on Fourier modeling and includes force calculations. The semianalytical modeling correctly predicts the behavior found in the

Stabilisation and precision pointing quadrupole magnets in the Compact Linear Collider (CLIC)

CERN Document Server

Janssens, Stef; Linde, Frank; van den Brand, Jo; Bertolini, Alessandro; Artoos, Kurt

This thesis describes the research done to provide stabilisation and precision positioning for the main beam quadrupole magnets of the Compact Linear Collider CLIC. The introduction describes why new particle accelerators are needed to further the knowledge of our universe and why they are linear. A proposed future accelerator is the Compact Linear Collider (CLIC) which consists of a novel two beam accelerator concept. Due to its linearity and subsequent single pass at the interaction point, this new accelerator requires a very small beam size at the interaction point, in order to increase collision effectiveness. One of the technological challenges, to obtain these small beam sizes at the interaction point, is to keep the quadrupole magnets aligned and stable to 1.5 nm integrated r.m.s. in vertical and 5 nm integrated root mean square (r.m.s.) in lateral direction. Additionally there is a proposal to create an intentional offset (max. 50 nm every 20 ms with a precision of +/- 1 nm), for several quadrupole ma...

Field-reversed mirror pilot reactor. Annual report

International Nuclear Information System (INIS)

Devoto, R.S.; Erickson, J.L.; Fink, J.H.

1980-09-01

This report concludes a two-year effort to design a near-term small-scale fusion power plant which, through its construction and operation, would be a direct and important step toward the commercialization of fusion energy. The fusion reactor pilot plant was designed under the ground rules that it must produce net power, be compact, have minimum total cost, and use near-term (late 1980's) engineering technology. The neutral beam driven, field-reversed mirror (FRM) was selected as the fusion plasma confinement concept around which the pilot plant was designed. Although the physics data base for this design is not yet well in hand, it is being pursued within the magnetic field-reversal framework of the US Mirror Fusion Program. Depending on the plasma size, the pilot plant would gross up to 19.8 MW(e) and would produce up to 10.7 MW(e) net, with the recirculated power used principally for the neutral beam injectors and refrigeration for the superconducting magnets

Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider

International Nuclear Information System (INIS)

Spencer, Cherrill M

2002-01-01

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0 -20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype. See High Reliability Prototype Quadrupole for the Next Linear Collider by C.E Rago, C.M SPENCER, Z. Wolf submitted to this conference

Open trap with ambipolar mirrors

International Nuclear Information System (INIS)

Dimov, G.I.; Zakajdakov, V.V.; Kishinevskij, M.E.

1977-01-01

Results of numerical calculations on the behaviour of a thermonuclear plasma, allowing for α-particles in a trap with longitudinal confinement of the main ions by ambipolar electric fields are presented. This trap is formed by connecting two small-volume ''mirrortrons'' to an ordinary open trap. Into the extreme mirrortrons, approximately 1-MeV ions are introduced continuously by ionization of atomic beams on the plasma, and approximately 10-keV ions are similarly introduced into the main central region of the trap. By a suitable choice of injection currents, the plasma density established in the extreme mirrortrons is higher than in the central region. As a result of the quasi-neutrality condition, a longitudinal ambipolar field forming a potential well not only for electrons but also for the central ions is formed in the plasma. When the depth of the well for the central ions is much greater than their temperature, their life-time considerably exceeds the time of confinement by the magnetic mirrors. As a result, the plasma density is constant over the entire length of the central mirrortron, including the regions near the mirrors, and an ambipolar field is formed only in the extreme mirrortrons. The distribution of central ions and ambipolar potential in the extreme mirrortrons is uniquely determined by the density distribution of fast extreme ions. It is shown in the present study that an amplification coefficient Q as high as desired can, in principle, be reached in the trap under consideration, allowing for α-particles. However, this requires high magnetic fields in the mirrors and a sufficient length of the central mirrotron. It is shown that for moderate values of Q=3-8, it is desirable not to confine the central fast α-particles. To achieve a coefficient of Q=5, it is necessary to create fields of 250 kG in the mirrors, and the length of the trap must not be greater than 100 m. (author)

Force analysis of linear induction motor for magnetic levitation system

NARCIS (Netherlands)

Kuijpers, A.A.; Nemlioglu, C.; Sahin, F.; Verdel, A.J.D.; Compter, J.C.; Lomonova, E.

2010-01-01

This paper presents the analyses of thrust and normal forces of linear induction motor (LIM) segments which are implemented in a rotating ring system. To obtain magnetic levitation in a cost effective and sustainable way, decoupled control of thrust and normal forces is required. This study includes

Criterion of magnetic saturation and simulation of nonlinear magnetization for a linear multi-core pulse transformer

International Nuclear Information System (INIS)

Zeng Zhengzhong; Kuai Bin; Sun Fengju; Cong Peitian; Qiu Aici

2002-01-01

The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasm owing to its compact, relatively low-cost and easy-to-handle characteristics. The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design, because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation. This work proposes analytical formulas of the criterion of magnetic saturation for the cores when the transformer drives practical loads. Furthermore, an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores. The numerical simulation with the model is used to evaluate the validity of the criterion. Both the criterion and the model are found to be in agreement with the experimental data

The compact mirrors with high pressure plasmas

International Nuclear Information System (INIS)

Anikeev, A.V.; Bagryansky, P.A.; Ivanov, A.A.; Lizunov, A.A.; Murakhtin, S.V.; Prikhodko, V.V.; Collatz, S.; Noack, K.

2004-01-01

The gas dynamic trap (GDP) experimental facility at the Budker Institute Novosibirsk is a long axial-symmetric mirror system with a high mirror ratio variable in the range of 12.5 - 100 for the confinement of a two-component plasma. One component is a collisional plasma with ion and electron temperatures up to 100 eV and density up to 10 14 cm -3 . The second component is the population of high-energetic fast ions with energies of 2-18 keV and a density up to 10 13 cm -3 which is produced by neutral beam injection (NBI). GDP is currently undergoing an upgrade whose first stage is the achievement of the synthesized hot ion plasmoid experiment (SHIP). This experiment aims at the investigation of plasmas and at the knowledge of plasma parameters that have never been achieved before in magnetic mirrors. The paper presents the physical concept of the SHIP experiment, the results of numerical pre-calculations and draws conclusions regarding possible scenarios of experiments. The simulation of a maximal NBI power regime with hydrogen injection gave a fast ion density of 1.2*10 14 cm -3 with a mean energy of 14 keV. The calculation of the deuterium injection regime with 2 MW NBI power gave a maximal fast ion density of 1.9*10 14 cm -3 with a beam energy of 9 keV. The calculation of an experimental scenario with reduced magnetic field resulted in a maximal β-value of 62%, so this regime is recommended for the study of high-β effects in plasmas confined in axial-symmetric mirrors

Measuring the Dispersion in Laser Cavity Mirrors using White-Light Interferometry

Science.gov (United States)

2008-03-01

mirrors. Two AlGaInP (aluminum gallium indium phosphide ) diode lasers are aligned such that one is polarized vertically while one is polarized...linear crystals, where the index of refraction depends on beam intensity. Short pulses with high peak intensities are well 14 suited to induce the...MEASURING THE DISPERSION OF LASER CAVITY MIRRORS USING WHITE-LIGHT INTERFEROMETRY THESIS Allison S

Stochastic field-line wandering in magnetic turbulence with shear. I. Quasi-linear theory

Energy Technology Data Exchange (ETDEWEB)

Shalchi, A. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Negrea, M.; Petrisor, I. [Department of Physics, University of Craiova, Association Euratom-MEdC, 13A.I.Cuza Str, 200585 Craiova (Romania)

2016-07-15

We investigate the random walk of magnetic field lines in magnetic turbulence with shear. In the first part of the series, we develop a quasi-linear theory in order to compute the diffusion coefficient of magnetic field lines. We derive general formulas for the diffusion coefficients in the different directions of space. We like to emphasize that we expect that quasi-linear theory is only valid if the so-called Kubo number is small. We consider two turbulence models as examples, namely, a noisy slab model as well as a Gaussian decorrelation model. For both models we compute the field line diffusion coefficients and we show how they depend on the aforementioned Kubo number as well as a shear parameter. It is demonstrated that the shear effect reduces all field line diffusion coefficients.

Stochastic field-line wandering in magnetic turbulence with shear. I. Quasi-linear theory

International Nuclear Information System (INIS)

Shalchi, A.; Negrea, M.; Petrisor, I.

2016-01-01

We investigate the random walk of magnetic field lines in magnetic turbulence with shear. In the first part of the series, we develop a quasi-linear theory in order to compute the diffusion coefficient of magnetic field lines. We derive general formulas for the diffusion coefficients in the different directions of space. We like to emphasize that we expect that quasi-linear theory is only valid if the so-called Kubo number is small. We consider two turbulence models as examples, namely, a noisy slab model as well as a Gaussian decorrelation model. For both models we compute the field line diffusion coefficients and we show how they depend on the aforementioned Kubo number as well as a shear parameter. It is demonstrated that the shear effect reduces all field line diffusion coefficients.

3D Analytical Calculation of Forces between Linear Halbach-Type Permanent Magnet Arrays

OpenAIRE

Allag , Hicham; Yonnet , Jean-Paul; Latreche , Mohamed E. H.

2009-01-01

International audience; Usely, in analytical calculation of magnetic and mechanical quantities of Halbach systems, the authors use the Fourier series approximation because the exact calculations are more difficult. In this work the interaction forces between linear Halbach arrays are analytically calculated thanks to our recent development 3D exact calculation of forces between two cuboïdal magnets with parallel and perpendicular magnetization. We essentially describe the way to separately ca...

Modelling of a linear PM machine including magnetic saturation and end effects : maximum force to current ratio

NARCIS (Netherlands)

Polinder, H.; Slootweg, J.G.; Hoeijmakers, M.J.; Compter, J.C.

2003-01-01

The use of linear permanent-magnet (PM) actuators increases in a wide variety of applications because of their high force density, robustness and accuracy. These linear PM motors are often heavily loaded during short intervals of high acceleration, so that magnetic saturation occurs. This paper

Design and thermal performances of a scalable linear Fresnel reflector solar system

International Nuclear Information System (INIS)

Zhu, Yanqing; Shi, Jifu; Li, Yujian; Wang, Leilei; Huang, Qizhang; Xu, Gang

2017-01-01

Highlights: • A scalable linear Fresnel reflector which can supply different temperatures is proposed. • Inclination design of the mechanical structure is used to reduce the end losses. • The maximum thermal efficiency of 64% is achieved in Guangzhou. - Abstract: This paper proposes a scalable linear Fresnel reflector (SLFR) solar system. The optical mirror field which contains an array of linear plat mirrors closed to each other is designed to eliminate the inter-low shading and blocking. Scalable mechanical mirror support which can place different number of mirrors is designed to supply different temperatures. The mechanical structure can be inclined to reduce the end losses. Finally, the thermal efficiency of the SLFR with two stage mirrors is tested. After adjustment, the maximum thermal efficiency of 64% is obtained and the mean thermal efficiency is higher than that before adjustment. The results indicate that the end losses have been reduced effectively by the inclination design and excellent thermal performance can be obtained by the SLFR after adjustment.

Optimal design of a double-sided linear motor with a multi-segmented trapezoidal magnet array for a high precision positioning system

International Nuclear Information System (INIS)

Lee, Moon G.; Gweon, Dae-Gab

2004-01-01

A comparative analysis is performed for linear motors adopting conventional and multi-segmented trapezoidal (MST) magnet arrays, respectively, for a high-precision positioning system. The proposed MST magnet array is a modified version of a Halbach magnet array. The MST array has trapezoidal magnets with variable shape and dimensions while the Halbach magnet array generally has a rectangular magnet with identical dimensions. We propose a new model that can describe the magnetic field resulting from the complex-shaped magnets. The model can be applied to both MST and conventional magnet arrays. Using the model, a design optimization of the two types of linear motors is performed and compared. The magnet array with trapezoidal magnets can produce more force than one with rectangular magnets when they are arrayed in a linear motor where there is a yoke with high permeability. After the optimization and comparison, we conclude that the linear motor with the MST magnet array can generate more actuating force per volume than the motor with the conventional array. In order to satisfy the requirements of next generation systems such as high resolution, high speed, and long stroke, the use of a linear motor with a MST array as an actuator in a high precision positioning system is recommended from the results obtained here

Active feedback stabilization of the flute instability in a mirror machine using field-aligned coils

International Nuclear Information System (INIS)

Lifshitz, A.; Be'ery, I.; Fisher, A.; Ron, A.; Fruchtman, A.

2012-01-01

A plasma confined in linear mirror machines is unstable even at low β, mainly because of the flute instability. One possible way to stabilize the plasma is to use active feedback to correct the plasma shape in real time. The theoretically investigated apparatus consists of feedback coils aligned with the magnetic field, immersed in a cold plasma around the hot core. When the current through the feedback coils changes, the plasma moves to conserve the magnetic flux via compressional Alfvén waves. An analytical model is used to find a robust feedback algorithm with zero residual currents. It is shown that due to the plasma's rotation, maximal stability is obtained with a large phase angle between the perturbations' modes and the feedback integral-like term. Finally, a two-dimensional MHD simulation implementing the above algorithm in fact shows stabilization of the plasma with zero residual currents. (paper)

Comparison of Thrust Characteristics in Pencil Sized Cylinder-type Linear Motors with Different Magnet Arrays

OpenAIRE

Nakaiwa, K; Yamada, A; Tashiro, K; Wakiwaka, H

2009-01-01

From a strong demand on the miniaturization of a chip mounter or a semiconductor device, the thrust improvement considering the magnets arrangement is studied. We accept a core stator with a Halbach type magnet array for a current linear motor. The thrust characteristics are compared with two kinds of mover, a NS magnet array and a Halbach magnet array.

Adaptive metal mirror for high-power CO2 lasers

Science.gov (United States)

Jarosch, Uwe-Klaus

1996-08-01

Spherical mirrors with a variable radius of curvature are used inside laser resonators as well as in the beam path between the laser and the workpiece. Commercially-available systems use piezoelectric actuators, or the pressure of the coolant, to deform the mirror surface. In both cases, the actuator and the cooling system influence each other. This interaction is avoided through the integration of the cooling system with the flexible mirror membrane. A multi- channel design leads to an optimized cooling effect, which is necessary for high power applications. The contour of the variable metal mirror depends on the mounting between the membrane and the mirror body and on the distribution of forces. Four cases of deformation can be distinguished for a circular elastic membrane. The realization of an adaptive metal mirror requires a technical compromise to be made. A mechanical construction is presented which combines an elastic hinge with the inlet and outlet of the coolant. For the deformation of the mirror membranes two actuators with different character of deformation are used. The superposition of the two deformations results in smaller deviations from the spherical surface shape than can be achieved using a single actuator. DC proportional magnets have been introduced as cheap and rigid actuators. The use of this adaptive mirror, either in a low pressure atmosphere of a gas laser resonator, or in an extra-cavity beam path is made possible through the use of a ventilation system.

Phase correction for a Michelson interferometer with misaligned mirrors

Science.gov (United States)

Goorvitch, D.

1975-01-01

The phase correction for a Michelson interferometer with misaligned mirrors in converging light is shown to give rise to a quadratic phase shift. In general, the calculation of a spectrum from the measured interferogram needs phase correction. Phase corrections have been well worked out for the cases of a linear phase shift and a phase that is slowly varying. The standard procedures for correcting calculated spectra need to be modified, however, to remove any phase errors resulting from misaligned mirrors.

Analysis and testing of a double armature brushless dc linear motor with NdFeB permanent magnets

International Nuclear Information System (INIS)

Filho, A.F.F.

1998-01-01

The use of high-energy product NdFeB permanent magnets benefits the design and features of a double armature brushless dc linear motor. As the linear motor is also slotless, its 5 mm airgap requires a source of high flux to overcome the reluctance and produce an adequate amount of force. The linear motor employs a topology that makes use of five permanent magnets to provide excitation flux. The permanent magnets are arranged in such a way that maximises the force the linear motor can deliver. The actuator produces a force up to 86.2 N at an armature current of 4.5 A. However, the topology makes the actuator prone to saturation. It affects the operation point of the permanent magnets, reduces the airgap flux density and the force, and increases flux leakage. To avoid saturation, a flux compensation scheme was conceived. The results are presented and assessed by means of finite element simulation and by experimental results that presented a good agreement. (orig.)

Design and analysis of an unconventional permanent magnet linear machine for energy harvesting

Science.gov (United States)

Zeng, Peng

This Ph.D. dissertation proposes an unconventional high power density linear electromagnetic kinetic energy harvester, and a high-performance two-stage interface power electronics to maintain maximum power abstraction from the energy source and charge the Li-ion battery load with constant current. The proposed machine architecture is composed of a double-sided flat type silicon steel stator with winding slots, a permanent magnet mover, coil windings, a linear motion guide and an adjustable spring bearing. The unconventional design of the machine is that NdFeB magnet bars in the mover are placed with magnetic fields in horizontal direction instead of vertical direction and the same magnetic poles are facing each other. The derived magnetic equivalent circuit model proves the average air-gap flux density of the novel topology is as high as 0.73 T with 17.7% improvement over that of the conventional topology at the given geometric dimensions of the proof-of-concept machine. Subsequently, the improved output voltage and power are achieved. The dynamic model of the linear generator is also developed, and the analytical equations of output maximum power are derived for the case of driving vibration with amplitude that is equal, smaller and larger than the relative displacement between the mover and the stator of the machine respectively. Furthermore, the finite element analysis (FEA) model has been simulated to prove the derived analytical results and the improved power generation capability. Also, an optimization framework is explored to extend to the multi-Degree-of-Freedom (n-DOF) vibration based linear energy harvesting devices. Moreover, a boost-buck cascaded switch mode converter with current controller is designed to extract the maximum power from the harvester and charge the Li-ion battery with trickle current. Meanwhile, a maximum power point tracking (MPPT) algorithm is proposed and optimized for low frequency driving vibrations. Finally, a proof

Equilibrium and stability of theta-pinch plasma in modified toroidal multiple mirror field

International Nuclear Information System (INIS)

Shiina, S.; Saito, K.; Osanai, Y.; Itagaki, T.; Karakizawa, T.; Gesso, H.; Todoroki, J.; Kawakami, I.; Yoshimura, H.

1976-01-01

To confine a high-beta plasma a new toroidal magnetic configuration with closed lines of force has been proposed [1]. The configuration is an appropriate superposition of l = 0, l = +- 1, l = +- 2,sup(...), helical fields. In this experiment, it is generated by modifying the multiple mirror field by enclosing the discharge tube in a copper shell which has longitudinal gap. This configuration is preferred for the wall stabilizing effect to that with the separated helical windings. The characteristics of the equilibrium conditions are examined based on the near-axis approximation theory and compared with the experimental results. The stability of plasma in the configurations with l = 0 field and with superposition of l = 0, l = +- 2 fields is investigated in linear geometry. (author)

Coating Thin Mirror Segments for Lightweight X-ray Optics

Science.gov (United States)

Chan, Kai-Wing; Sharpe, Marton V.; Zhang, William; Kolosc, Linette; Hong, Melinda; McClelland, Ryan; Hohl, Bruce R.; Saha, Timo; Mazzarellam, James

2013-01-01

Next generations lightweight, high resolution, high throughput optics for x-ray astronomy requires integration of very thin mirror segments into a lightweight telescope housing without distortion. Thin glass substrates with linear dimension of 200 mm and thickness as small as 0.4 mm can now be fabricated to a precision of a few arc-seconds for grazing incidence optics. Subsequent implementation requires a distortion-free deposition of metals such as iridium or platinum. These depositions, however, generally have high coating stresses that cause mirror distortion. In this paper, we discuss the coating stress on these thin glass mirrors and the effort to eliminate their induced distortion. It is shown that balancing the coating distortion either by coating films with tensile and compressive stresses, or on both sides of the mirrors is not sufficient. Heating the mirror in a moderately high temperature turns out to relax the coated films reasonably well to a precision of about a second of arc and therefore provide a practical solution to the coating problem.

Beam line optics technologies series (7). Orthopedic treatment of sharp of light (reflecting mirror)

International Nuclear Information System (INIS)

Uruga, Tomoya; Nomura, Masaharu

2006-01-01

A reflecting mirror (mirror) is the most popular light device for orthopedic treatment of the shape of light. The paper explains the kinds of mirror for hard X-ray field and its applications in order to think the objects of mirror and how to adjust it when user experiment on the beam-line. The basic knowledge of reflection of X-ray, a use of mirror, the kinds of condenser mirror, the influence factors on the condenser size, arrangement of mirror in the hard X-ray beam-line, what kinds of mirror are necessary, evaluation of performance of mirror and adjustment, and troubles and measures are described. Layout in optics hutch at BL01B1 at SPring-8, refraction and total reflection of X-rays at surface, reflectivity of Rh and Pt with ideal surface as a function of photon energy, effects of surface roughness on reflectivity of Rh, calculated beam sizes for typical SPring-8 mirror as a function of magnification, schematic drawing of mirror, standard mirror system for vertical deflection in bending magnet beam-line, and observed and calculated reflectivity of Rh double mirror at BL01B1 at SPring-8 are illustrated. (S.Y)

Simulation of dynamics of a permanent magnet linear actuator

DEFF Research Database (Denmark)

Yatchev, Ivan; Ritchie, Ewen

2010-01-01

Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

High quality multilayer mirrors for soft X-rays

Energy Technology Data Exchange (ETDEWEB)

Grimmer, H.; Boeni, P.; Breitmeier, U.; Clemens, D.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Mertins, H.C.; Schaefers, F. [BESSY, Berlin (Germany)

1997-09-01

In an effort to develop optical components for X-rays with wavelengths in the water window (2.3 -4.4 nm) multilayer structures have been designed for the following applications: in transmission as phase shifters to change linear into circular polarization, in reflection as mirrors close to normal incidence and as linear polarizers at an angle of incidence of 45{sup o}. (author) 1 fig., 1 tab., 1 ref.

Magnetically Suspended Linear Pulse Motor for Semiconductor Wafer Transfer in Vacuum Chamber

Science.gov (United States)

Moriyama, Shin-Ichi; Hiraki, Naoji; Watanabe, Katsuhide; Kanemitsu, Yoichi

1996-01-01

This paper describes a magnetically suspended linear pulse motor for a semiconductor wafer transfer robot in a vacuum chamber. The motor can drive a wafer transfer arm horizontally without mechanical contact. In the construction of the magnetic suspension system, four pairs of linear magnetic bearings for the lift control are used for the guidance control as well. This approach allows us to make the whole motor compact in size and light in weight. The tested motor consists of a double-sided stator and a transfer arm with a width of 50 mm and a total length of 700 mm. The arm, like a ladder in shape, is designed as the floating element with a tooth width of 4 mm (a tooth pitch of 8 mm). The mover mass is limited to about 1.6 kg by adopting such an arm structure, and the ratio of thrust to mover mass reaches to 3.2 N/kg under a broad air gap (1 mm) between the stator teeth and the mover teeth. The performance testing was carried out with a transfer distance less than 450 mm and a transfer speed less than 560 mm/s. The attitude of the arm was well controlled by the linear magnetic bearings with a combined use, and consequently the repeatability on the positioning of the arm reached to about 2 micron. In addition, the positioning accuracy was improved up to about 30 micron through a compensation of the 128-step wave current which was used for the micro-step drive with a step increment of 62.5 micron.

Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet

CERN Document Server

Frisch, J; Decker, V; Hendrickson, L; Markiewicz, T W; Partridge, R; Seryi, Andrei

2004-01-01

The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.

Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet

International Nuclear Information System (INIS)

Frisch, Josef; Chang, Allison; Decker, Valentin; Doyle, Eric; Eriksson, Leif; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Partridge, Richard; Seryi, Andrei; SLAC

2006-01-01

The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system

Thermal performance of the MFTF magnets

International Nuclear Information System (INIS)

VanSant, J.H.

1983-01-01

A yin-yang pair of liquid-helium (LHe) cooled, superconducting magnets were tested last year at the Lawrence Livermore National Laboratory (LLNL) as part of a series of tests with the Mirror Fusion Test Facility (MFTF). These tests were performed to determine the success of engineering design used in major systems of the MFTF and to provide a technical base for rescoping from a single-mirror facility to the large tandem-mirror configuration (MFTF-B) now under construction. The magnets were cooled, operated at their design current and magnetic field, and warmed to atmospheric temperature. In this report, we describe their thermal behavior during these tests

Magnetic mirror fusion research at the Lawrence Livermore Laboratory

International Nuclear Information System (INIS)

Post, R.F.

1979-01-01

An overall view is given of progress and plans for pressing forward with mirror research at Livermore. No detail is given on any one subject, and many interesting investigations being carried out at University laboratories in the U.S. that augment and support efforts at Livermore are omitted

Optical levitation of a mirror for reaching the standard quantum limit

Science.gov (United States)

Michimura, Yuta; Kuwahara, Yuya; Ushiba, Takafumi; Matsumoto, Nobuyuki; Ando, Masaki

2017-06-01

We propose a new method to optically levitate a macroscopic mirror with two vertical Fabry-P{\\'e}rot cavities linearly aligned. This configuration gives the simplest possible optical levitation in which the number of laser beams used is the minimum of two. We demonstrate that reaching the standard quantum limit (SQL) of a displacement measurement with our system is feasible with current technology. The cavity geometry and the levitated mirror parameters are designed to ensure that the Brownian vibration of the mirror surface is smaller than the SQL. Our scheme provides a promising tool for testing macroscopic quantum mechanics.

Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

Energy Technology Data Exchange (ETDEWEB)

Mishra, S.; Gammon, W.J.; Pappas, D.P. [Virginia Commonwealth Univ., Richmond, VA (United States)] [and others

1997-04-01

The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield.

Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

International Nuclear Information System (INIS)

Mishra, S.; Gammon, W.J.; Pappas, D.P.

1997-01-01

The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield

Mirror fusion reactors

International Nuclear Information System (INIS)

Carlson, G.A.; Moir, R.W.

1978-01-01

We have carried out conceptual design studies of fusion reactors based on the three current mirror confinement concepts: the standard mirror, the tandem mirror, and the field-reversed mirror. Recent studies of the standard mirror have emphasized its potential as a fusion-fission hybrid reactor, designed to produce fission fuel for fission reactors. We have designed a large commercial hybrid based on standard mirror confinement, and also a small pilot plant hybrid. Tandem mirror designs include a commercial 1000 MWe fusion power plant and a nearer term tandem mirror hybrid. Field-reversed mirror designs include a multicell commercial reactor producing 75 MWe and a single cell pilot plant

Mirror fusion reactors

International Nuclear Information System (INIS)

Anon.

1978-01-01

Conceptual design studies were made of fusion reactors based on the three current mirror-confinement concepts: the standard mirror, the tandem mirror, and the field-reversed mirror. Recent studies of the standard mirror have emphasized its potential as a fusion-fission hybrid reactor, designed to produce fuel for fission reactors. We have designed a large commercial hybrid and a small pilot-plant hybrid based on standard mirror confinement. Tandem mirror designs include a commercial 1000-MWe fusion power plant and a nearer term tandem mirror hybrid. Field-reversed mirror designs include a multicell commercial reactor producing 75 MWe and a single-cell pilot plant

Mirror agnosia and the mirrored-self misidentification delusion: a hypnotic analogue.

Science.gov (United States)

Connors, Michael H; Cox, Rochelle E; Barnier, Amanda J; Langdon, Robyn; Coltheart, Max

2012-05-01

Mirrored-self misidentification is the delusional belief that one's reflection in the mirror is a stranger. Current theories suggest that one pathway to the delusion is mirror agnosia (a deficit in which patients are unable to use mirror knowledge when interacting with mirrors). This study examined whether a hypnotic suggestion for mirror agnosia can recreate features of the delusion. Ten high hypnotisable participants were given either a suggestion to not understand mirrors or to see the mirror as a window. Participants were asked to look into a mirror and describe what they saw. Participants were tested on their understanding of mirrors and received a series of challenges. Participants then received a detailed postexperimental inquiry. Three of five participants given the suggestion to not understand mirrors reported seeing a stranger and maintained this belief when challenged. These participants also showed signs of mirror agnosia. No participants given the suggestion to see a window reported seeing a stranger. Results indicate that a hypnotic suggestion for mirror agnosia can be used to recreate the mirrored-self misidentification delusion. Factors influencing the effectiveness of hypnotic analogues of psychopathology, such as participants' expectations and interpretations, are discussed.

Investigation of a 7-pole/6-slot Halbach-magnetized permanent-magnet linear alternator used for free-piston stirling engines

Science.gov (United States)

Zheng, Ping; Tong, Chengde; Zhao, Jing; Yu, Bin; Li, Lin; Bai, Jingang; Zhang, Lu

2012-04-01

This paper investigates a 7-pole/6-slot Halbach-magnetized permanent-magnet linear alternator used for free piston Stirling engines (FPSEs). Taking the advantages of Halbach array, a 1 kW prototype alternator is designed. Considering the rms value of electromotive force (EMF) and harmonic distortion, the optimal length ratio of the axial- and radial-magnetized permanent magnets and thicknesses of the permanent magnets are optimized by 2D finite element method. The alternator detent force, which is an important factor for smooth operation of FPSEs, is studied by optimizing slot tip and end tooth. The load and thermal performances of the final design are simulated. A prototype alternator was designed, built and tested. Experimental data indicated satisfactory design.

On improved confinement in mirror plasmas by a radial electric field

Science.gov (United States)

Ågren, O.; Moiseenko, V. E.

2017-11-01

A weak radial electric field can suppress radial excursions of a guiding center from its mean magnetic surface. The physical origin of this effect is the smearing action by a poloidal E × B rotation, which tend to cancel out the inward and outward radial drifts. A use of this phenomenon may provide larger margins for magnetic field shaping with radial confinement of particles maintained in the collision free idealization. Mirror fields, stabilized by a quadrupolar field component, are of particular interest for their MHD stability and the possibility to control the quasi neutral radial electric field by biased potential plates outside the confinement region. Flux surface footprints on the end tank wall have to be traced to avoid short-circuiting between biased plates. Assuming a robust biasing procedure, moderate voltage demands for the biased plates seems adequate to cure even the radial excursions of Yushmanov ions which could be locally trapped near the mirrors. Analytical expressions are obtained for a magnetic quadrupolar mirror configuration which possesses minimal radial magnetic drifts in the central confinement region. By adding a weak controlled radial quasi-neutral electric field, the majority of gyro centers are predicted to be forced to move even closer to their respective mean magnetic surface. The gyro center radial coordinate is in such a case an accurate approximation for a constant of motion. By using this constant of motion, the analysis is in a Vlasov description extended to finite β. A correspondence between that Vlasov system and a fluid description with a scalar pressure and an electric potential is verified. The minimum B criterion is considered and implications for flute mode stability in the considered magnetic field is analyzed. By carrying out a long-thin expansion to a higher order, the validity of the calculations are extended to shorter and more compact device designs.

Onset of superradiant instabilities in the composed Kerr-black-hole–mirror bomb

Directory of Open Access Journals (Sweden)

Shahar Hod

2014-09-01

Full Text Available It was first pointed out by Press and Teukolsky that a system composed of a spinning Kerr black hole surrounded by a reflecting mirror may develop instabilities. The physical mechanism responsible for the development of these exponentially growing instabilities is the superradiant amplification of bosonic fields confined between the black hole and the mirror. A remarkable feature of this composed black-hole–mirror-field system is the existence of a critical mirror radius, rmstat, which supports stationary (marginally-stable field configurations. This critical (‘stationary’ mirror radius marks the boundary between stable and unstable black-hole–mirror-field configurations: composed systems whose confining mirror is situated in the region rmrmstat are unstable (that is, there are confined field modes which grow exponentially over time. In the present paper we explore this critical (marginally-stable boundary between stable and explosive black-hole–mirror-field configurations. It is shown that the innermost (smallest radius of the confining mirror which allows the extraction of rotational energy from a spinning Kerr black hole approaches the black-hole horizon radius in the extremal limit of rapidly-rotating black holes. We find, in particular, that this critical mirror radius (which marks the onset of superradiant instabilities in the composed system scales linearly with the black-hole temperature.

A Linear Tetranuclear Dysprosium(III) Compound Showing Single-Molecule Magnet Behavior

Energy Technology Data Exchange (ETDEWEB)

Ke, Hongshan; Xu, Gong Feng; Guo, Yun-Nan; Gamez, Patrick; Beavers, Christine M; Teat, Simon J; Tang, Jinkui

2010-04-20

Although magnetic measurements reveal a single-relaxation time for a linear tetranuclear Dy(III) compound, the wide distribution of the relaxation time observed clearly suggests the presence of two slightly different anisotropic centres, therefore opening new avenues for investigating the relaxation dynamics of lanthanide aggregates.

Design of the science-fold mirrors for the Gemini telescopes

Science.gov (United States)

Peschel, Thomas; Damm, Christoph; Heilemann, Wolfgang

2000-07-01

As a part of the Acquisition and Guidance Unit for the Gemini project a light-weight, 50 cm flat mirror has been designed at the Fraunhofer Institute for Applied Optics and Precision Mechanics in Jena as a subcontractor of the Carl Zeiss Jena company. A light-weight design of the mirror and its mount was essential since the total mass of the whole assembly including the positioning system was limited to 50 kg while interferometric quality of the mirror surface was required for arbitrary orientation. The overall surface error was below 54 nm r.m.s. while 27 nm was achieved in the central part. The mirror was fabricated from low-expansion glass ceramics to avoid thermally induced deformations. By milling pockets into its rear surface the mass of the mirror was reduced by 70%. The mirror is mounted cinematically via six solid-state hinges to three steel levers. The levers are connected to the mount frame at their centers via ball-and- sphere joints. This arrangement determines the position of the mirror uniquely while it allows for the thermal expansion of the mount frame. The position of the mirror as well as its tilt around an axis perpendicular to the optical one may be controlled a precision of 20 micrometers and 3 arcsec, respectively. The tilt axis is driven directly by two high- torque motors. To avoid an excessive power consumption of the motors the torque of the mirror head to be compensated for by a counterweight mechanism. The mirror may be deployed into the optical path using spindle driven linear rails.

Superconducting magnets for the RAON electron cyclotron resonance ion source.

Science.gov (United States)

Choi, S; Kim, Y; Hong, I S; Jeon, D

2014-02-01

The RAON linear accelerator of Rare Isotope Science Project has been developed since 2011, and the superconducting magnet for ECRIS was designed. The RAON ECR ion source was considered as a 3rd generation source. The fully superconducting magnet has been designed for operating using 28 GHz radio frequency. The RAON ECRIS operates in a minimum B field configuration which means that a magnetic sextupole field for radial confinement is superimposed with a magnetic mirror field for axial confinement. The highest field strength reaches 3.5 T on axis and 2 T at the plasma chamber wall for operating frequency up to 28 GHz. In this paper, the design results are presented of optimized superconducting magnet consisting of four solenoids and sextupole. The prototype magnet for ECRIS was fabricated and tested to verify the feasibility of the design. On the basis of test results, a fully superconducting magnet will be fabricated and tested.

Preliminary design of a Tandem-Mirror-Next-Step facility

International Nuclear Information System (INIS)

Damm, C.C.; Doggett, J.N.; Bulmer, R.H.

1980-01-01

The Tandem-Mirror-Next-Step (TMNS) facility is designed to demonstrate the engineering feasibility of a tandem-mirror reactor. The facility is based on a deuterium-tritium (D-T) burning, tandem-mirror device with a fusion power output of 245 MW. The fusion power density in the central cell is 2.1 MW/m 3 , with a resultant neutron wall loading of 0.5 MW/m 2 . Overall machine length is 116 m, and the effective central-cell length is 50.9 m. The magnet system includes end cells with yin-yang magnets to provide magnetohydrodynamic (MHD) stability and thermal-barrier cells to help achieve a plasma Q of 4.7 (where Q = fusion power/injected power). Neutral beams at energies up to 200 keV are used for plasma heating, fueling, and barrier pumping. Electron cyclotron resonant heating at 50 and 100 GHz is used to control the electron temperature in the barriers. Based on the resulting engineering design, the overall cost of the facility is estimated to be just under $1 billion. Unresolved physics issues include central-cell β-limits against MHD ballooning modes (the assumed reference value of β exceeds the current theory-derived limit), and the removal of thermalized α-particles from the plasma

Novel permanent magnet linear motor with isolated movers: analytical, numerical and experimental study.

Science.gov (United States)

Yan, Liang; Peng, Juanjuan; Jiao, Zongxia; Chen, Chin-Yin; Chen, I-Ming

2014-10-01

This paper proposes a novel permanent magnet linear motor possessing two movers and one stator. The two movers are isolated and can interact with the stator poles to generate independent forces and motions. Compared with conventional multiple motor driving system, it helps to increase the system compactness, and thus improve the power density and working efficiency. The magnetic field distribution is obtained by using equivalent magnetic circuit method. Following that, the formulation of force output considering armature reaction is carried out. Then inductances are analyzed with finite element method to investigate the relationships of the two movers. It is found that the mutual-inductances are nearly equal to zero, and thus the interaction between the two movers is negligible. A research prototype of the linear motor and a measurement apparatus on thrust force have been developed. Both numerical computation and experiment measurement are conducted to validate the analytical model of thrust force. Comparison shows that the analytical model matches the numerical and experimental results well.

High beta capture and mirror confinement of laser produced plasmas. Semiannual report, July 1, 1975--January 31, 1976

International Nuclear Information System (INIS)

Haught, A.F.; Polk, D.H.; Fader, W.J.; Tomlinson, R.G.; Jong, R.A.; Ard, W.B.; Mensing, A.E.; Churchill, T.L.; Stufflebeam, J.H.; Bresnock, F.J.

1976-01-01

The Laser Initiated Target Experiment (LITE) at the United Technologies Research Center is designed to address the target plasma buildup approach to a steady state mirror fusion device. A dense, mirror confined, target plasma is produced by high power laser irradiation of a solid lithium hydride particle, electrically suspended in a vacuum at the center of an established minimum-B magnetic field. Following expansion in and capture by the magnetic field, this target plasma is irradiated by an energetic neutral hydrogen beam. Charge exchange collisions with energetic beam particles serve to heat the confined plasma while ionization of the neutral beam atoms and trapping in the mirror magnetic field add particles to the confined plasma. For sufficiently high beam intensities, confined plasmas losses will be offset so that buildup of the plasma density occurs, thus demonstrating sustenance and fueling as well as the heating by neutral beam injection of a steady state mirror fusion device. Investigations of the decay of the magnetically confined target plasmas and initial studies of energetic neutral beam injection into confined target plasmas, conducted during this report period, are presented. Additional development of the LITE experimental systems including improvements in the laser plasma production facility, the energetic neutral beam line, and the heavy ion probe diagnostic is reported. A series of calculations on enhanced scattering and classical decay for plasma mirror confined in a LITE type system are discussed

Contactless and absolute linear displacement detection based upon 3D printed magnets combined with passive radio-frequency identification

Science.gov (United States)

Windl, Roman; Abert, Claas; Bruckner, Florian; Huber, Christian; Vogler, Christoph; Weitensfelder, Herbert; Suess, Dieter

2017-11-01

Within this work a passive and wireless magnetic sensor, to monitor linear displacements, is proposed. We exploit recent advances in 3D printing and fabricate a polymer bonded magnet with a spatially linear magnetic field component corresponding to the length of the magnet. Regulating the magnetic compound fraction during printing allows specific shaping of the magnetic field distribution. A giant magnetoresistance magnetic field sensor is combined with a radio-frequency identification tag in order to passively monitor the exerted magnetic field of the printed magnet. Due to the tailored magnetic field, a displacement of the magnet with respect to the sensor can be detected within the sub-mm regime. The sensor design provides good flexibility by controlling the 3D printing process according to application needs. Absolute displacement detection using low cost components and providing passive operation, long term stability, and longevity renders the proposed sensor system ideal for structural health monitoring applications.

Contactless and absolute linear displacement detection based upon 3D printed magnets combined with passive radio-frequency identification

Directory of Open Access Journals (Sweden)

Roman Windl

2017-11-01

Full Text Available Within this work a passive and wireless magnetic sensor, to monitor linear displacements, is proposed. We exploit recent advances in 3D printing and fabricate a polymer bonded magnet with a spatially linear magnetic field component corresponding to the length of the magnet. Regulating the magnetic compound fraction during printing allows specific shaping of the magnetic field distribution. A giant magnetoresistance magnetic field sensor is combined with a radio-frequency identification tag in order to passively monitor the exerted magnetic field of the printed magnet. Due to the tailored magnetic field, a displacement of the magnet with respect to the sensor can be detected within the sub-mm regime. The sensor design provides good flexibility by controlling the 3D printing process according to application needs. Absolute displacement detection using low cost components and providing passive operation, long term stability, and longevity renders the proposed sensor system ideal for structural health monitoring applications.

Report of the workshop on rf heating in mirror systems

International Nuclear Information System (INIS)

Price, R.E.; Woo, J.T.

1980-08-01

This report is prepared from the proceedings of the Workshop on RF Heating in Magnetic Mirror Systems held at DOE Headquarters in Washington, DC, on March 10-12, 1980. The workshop was organized into four consecutive half-day sessions of prepared talks and one half-day discussion. The first session on tandem mirror concepts and program plans served to identify the opportunities for the application of rf power and the specific approaches that are being pursued. A summary of the ideas presented in this session is given. The following sessions of the workshop were devoted to an exposition of current theoretical and experimental knowledge on the interaction of rf power with magnetically confined, dense, high temperature plasmas at frequencies near the electron cyclotron resonance, lower hybrid resonance and ion cyclotron resonance (including magnetosonic) ranges. The conclusions from these proceedings are presented

ICRF wave propagation and absorption in axisymmetric mirrors. Annual report, July 1, 1985-February 28, 1986

International Nuclear Information System (INIS)

Todd, A.M.M.; Phillips, M.W.

1986-04-01

A numerical code called GARFIELD has been developed to calculate the structure of ICRF electric fields in axisymmetric mirrors. It is being used to investigate ICRF wave structure of central cells of tandem mirror experiments. Fields are solved on a 2-D grid in the axial and radial directions. This permits us to study the effect that axial as well as radial variations of the magnetic field and density have on ICRF wave propagation and absorption. Much of this time frame was spent writing the code and refining the numerics. Initial calculations have been completed for the Phaedrus tandem mirror. These show that there is an evanescent fast wave structure in the radial direction, a standing wave formation in the axial direction, and a small amount of propagating ion cyclotron wave towards a shallow magnetic beach in the center of the mirror. In general, the fields peak on the outside which would show that the resulting pondermotive force would tend to stabilize the plasma

Current results of the tandem mirror experiment

International Nuclear Information System (INIS)

Drake, R.P.

1980-01-01

The basic operating characteristics of the Tandem Mirror Experiment, (TMX) at the Lawrence Livermore Laboratory in the USA have been established. Tandem-mirror plasmas have been produced using neutral-beam-fueled end plugs and a gas-fueled center cell. An axial potential well between the end plugs has been measured. There is direct evidence that this potential well enhances the axial confinement of the center-cell ions. The observed densities and loss currents are consistent with preliminary studies of the particle sources and losses near the magnetic axis. The observed confinement is consistent with theory when plasma fluctuations are low. When the requirement of drift-cyclotron loss-cone mode stability is violated, the plasma fluctuations degrade the center-cell confinement

The influence of mirror configurations near the lower hybrid resonance

International Nuclear Information System (INIS)

Glomski, G.; Heinrich, B.; Schlueter, H.

1976-01-01

Hydrogen plasmas in magnetic mirror configurations are generated by microwaves and inductively coupled to a weak rf-source. In contrast to previous investigations of the rf-frequency is varied; resonant behaviour near the lower hybrid frequency is found, attributable to radial eigenmodes. The influence of various mirror ratios and consequently varying axial density gradients on the position of the modes is studied. Shifts of the coupling coil are found to be of minor importance, since the resonant behaviour is dominated by oscillations of the whole plasma body. (orig.) [de

MODELING OF OPERATION OF COAXIAL-LINEAR MOTORS WITH AXIAL AND RADIAL DIRECTIONS OF MAGNETIZATION OF PERMANENT MAGNETS IN DYNAMIC MODE

Directory of Open Access Journals (Sweden)

G.M. Golenkov

2014-12-01

Full Text Available Theoretical and experimental investigations of the amplitude, phase and inertia-power frequency characteristics of two types of coaxial-linear electric motors of back-and-forth motion with permanent magnets, which magnetization vector is directed axially and radially relative to the axis of the runner are carried out. The comparative analysis of characteristics of these motors is presented.

Damping and non-linearity of a levitating magnet in rotation above a superconductor

International Nuclear Information System (INIS)

Druge, J; Jean, C; Laurent, O; Méasson, M-A; Favero, I

2014-01-01

We study the dissipation of moving magnets in levitation above a superconductor. The rotation motion is analyzed using optical tracking techniques. It displays a remarkable regularity together with long damping time up to several hours. The magnetic contribution to the damping is investigated in detail by comparing 14 distinct magnetic configurations and points towards amplitude-dependent dissipation mechanisms. The non-linear dynamics of the mechanical rotation motion is also revealed and described with an effective Duffing model. The magnetic mechanical damping is consistent with measured hysteretic cycles M(H) that are discussed within a modified critical state model. The obtained picture of the coupling of levitating magnets to their environment sheds light on their potential as ultra-low dissipation mechanical oscillators for high precision physics. (paper)

Optical Levitation of a Mirror for Reaching the Standard Quantum Limit

OpenAIRE

Michimura, Yuta; Kuwahara, Yuya; Ushiba, Takafumi; Matsumoto, Nobuyuki; Ando, Masaki

2016-01-01

We propose a new method to optically levitate a macroscopic mirror with two vertical Fabry-P{\\'e}rot cavities linearly aligned. This configuration gives the simplest possible optical levitation in which the number of laser beams used is the minimum of two. We demonstrate that reaching the standard quantum limit (SQL) of a displacement measurement with our system is feasible with current technology. The cavity geometry and the levitated mirror parameters are designed to ensure that the Brownia...

Application of magnets with azimuthal field variation in charged particle optics

International Nuclear Information System (INIS)

Dojnikov, N.I.; Lamzin, E.A.; Malitskij, N.D.

1989-01-01

Examples of concrete application of magnets with azimuthal field variation are presented. Magnetic mirror and bending-focusing device representing a single magnet with azimuthal field variation, providing achromatic beam bending, are used in the LUEh-40m therapeutic acceleration. A single magnet with azimuthal field variation is also used in magnetic mirror. Achromatic magnet for the Elektronika U-003 10 MeV accelerator is fabricated and examined. 2 refs.; 5 figs

Computation of misalignment and primary mirror astigmatism figure error of two-mirror telescopes

Science.gov (United States)

Gu, Zhiyuan; Wang, Yang; Ju, Guohao; Yan, Changxiang

2018-01-01

Active optics usually uses the computation models based on numerical methods to correct misalignments and figure errors at present. These methods can hardly lead to any insight into the aberration field dependencies that arise in the presence of the misalignments. An analytical alignment model based on third-order nodal aberration theory is presented for this problem, which can be utilized to compute the primary mirror astigmatic figure error and misalignments for two-mirror telescopes. Alignment simulations are conducted for an R-C telescope based on this analytical alignment model. It is shown that in the absence of wavefront measurement errors, wavefront measurements at only two field points are enough, and the correction process can be completed with only one alignment action. In the presence of wavefront measurement errors, increasing the number of field points for wavefront measurements can enhance the robustness of the alignment model. Monte Carlo simulation shows that, when -2 mm ≤ linear misalignment ≤ 2 mm, -0.1 deg ≤ angular misalignment ≤ 0.1 deg, and -0.2 λ ≤ astigmatism figure error (expressed as fringe Zernike coefficients C5 / C6, λ = 632.8 nm) ≤0.2 λ, the misaligned systems can be corrected to be close to nominal state without wavefront testing error. In addition, the root mean square deviation of RMS wavefront error of all the misaligned samples after being corrected is linearly related to wavefront testing error.

Design of Electromagnetic Moving-coil type Voice Coil Motor for Scanning mirror of Barcode reader

Energy Technology Data Exchange (ETDEWEB)

Shin, Bu Hyun; Lee, Jeong Woo; Shim, Hyun Ho; Park, Sang Goo [Hanbat National Univ., Daejeon (Korea, Republic of); Lee, Seung Yop [Sogang Univ., Seoul (Korea, Republic of)

2016-01-15

A voice coil actuator with moving coil type for scanning mirror system of barcode reader has been developed. The actuator has a simple structure including a magnet, a coil and a pin. The performance of the actuator is analyzed by a linearized theoretical model. And the dynamic performance of the proposed actuator is predicted through motor constant and restoring constant obtained by finite element simulations. The theoretical model was verified by the prototype which has 64 Hz resonance frequency and 60 deg reflecting angle. We also discovered that that 3 V input can make the actuator rotate over 61.8 deg reflecting angle at 50 Hz resonance frequency. The proposed actuator can simplify its driving configuration because of its implementation of open-loop control.

Combined Simulation of a Micro Permanent Magnetic Linear Contactless Displacement Sensor

Directory of Open Access Journals (Sweden)

Jing Gao

2010-09-01

Full Text Available The permanent magnetic linear contactless displacement (PLCD sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be used for microelectromechanical system (MEMS measurements is designed and simulated with the CST EM STUDIO® software, including building a virtual model, magnetostatic calculations, low frequency calculations, steady current calculations and thermal calculations. The influence of some important parameters such as air gap dimension, working frequency, coil current and eddy currents etc. is studied in depth.

Axicell MFTF-B superconducting-magnet system

International Nuclear Information System (INIS)

Wang, S.T.; Bulmer, R.; Hanson, C.; Hinkle, R.; Kozman, T.; Shimer, D.; Tatro, R.; VanSant, J.; Wohlwend, J.

1982-01-01

The Axicell MFTF-B magnet system will provide the field environment necessary for tandem mirror plasma physics investigation with thermal barriers. The performance of the device will stimulate DT to achieve energy break-even plasma conditions. Operation will be with deuterium only. There will be 24 superconducting coils consisting of 2 sets of yin-yang pairs, 14 central-cell solenoids, 2 sets of axicell mirror-coil pairs, and 2 transition coils between the axicell mirror coil-pairs and the yin-yang coils. This paper describes the progress in the design and construction of MFTF-B Superconducting-Magnet System

Linear magnetic anomalies and tectonic development of the middle Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

-By analyzing the magnetic anomalies, the linear magnetic anomalies in the middle Okinawa Trough are identified. It means that the crust along the spreading axis is broken, and new oceanic crust is formed. Geophysical data have revealed that a model of three extensive episodes occurs in the Okinawa Trough, which can be named as "doming episode" from the Middle to Late Miocene (Phase I), the episode from the Pliocence to Early Pleistocene (Phase Ⅱ ), and the recent "spreading episode" (Phase Ⅲ ). The magnetic anomalies in the middle Okinawa Trough are very similar to those found in the middle Red Sea, indicating that the Okinawa Trough is developing towards the "Red Sea stage". Similar to the Red Sea, there are a "main trough" and a "axial trough" in the Okinawa Trough.

Magnetic Properties of linear chain compounds formed by lanthanide (III) ions and nitronyl-nitroxide radicals

Energy Technology Data Exchange (ETDEWEB)

Benelli, C.; Caneschi, A.; Gatteschi, D.; Pardi, L. (Florence Univ. (IT)); Rey, P. (CEA Centre d' Etudes Nucleaires de Grenoble, 38 (FR). Dept. de Recherche Fondamentale)

1988-12-01

The magnetic properties of novel linear chain compounds containing lanthanide (III) ions (gadolinium, europium) coupled to stable nitronyl-nitroxide radicals are reported. The metal ions and the radicals are regularly alternating along the chain. The magnetic behaviors appears to be dominated by antiferromagnetic interactions between the radicals.

Magnetic Properties of linear chain compounds formed by lanthanide (III) ions and nitronyl-nitroxide radicals

International Nuclear Information System (INIS)

Benelli, C.; Caneschi, A.; Gatteschi, D.; Pardi, L.; Rey, P.

1988-01-01

The magnetic properties of novel linear chain compounds containing lanthanide (III) ions (gadolinium, europium) coupled to stable nitronyl-nitroxide radicals are reported. The metal ions and the radicals are regularly alternating along the chain. The magnetic behaviors appears to be dominated by antiferromagnetic interactions between the radicals

Magnetic domain structure and magnetically-induced reorientation in Ni–Mn–Ga magnetic shape memory alloy

Czech Academy of Sciences Publication Activity Database

Heczko, Oleg; Bradshaw, V.

2017-01-01

Roč. 131, č. 4 (2017), s. 1063-1065 ISSN 0587-4246 R&D Projects: GA ČR GA15-00262S Institutional support: RVO:68378271 Keywords : magnetic shape memory effect * magnetic domain structure * 3D visualization * domain mirroring Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.469, year: 2016

Topological mirror superconductivity.

Science.gov (United States)

Zhang, Fan; Kane, C L; Mele, E J

2013-08-02

We demonstrate the existence of topological superconductors (SCs) protected by mirror and time-reversal symmetries. D-dimensional (D=1, 2, 3) crystalline SCs are characterized by 2(D-1) independent integer topological invariants, which take the form of mirror Berry phases. These invariants determine the distribution of Majorana modes on a mirror symmetric boundary. The parity of total mirror Berry phase is the Z(2) index of a class DIII SC, implying that a DIII topological SC with a mirror line must also be a topological mirror SC but not vice versa and that a DIII SC with a mirror plane is always time-reversal trivial but can be mirror topological. We introduce representative models and suggest experimental signatures in feasible systems. Advances in quantum computing, the case for nodal SCs, the case for class D, and topological SCs protected by rotational symmetries are pointed out.

On determining fluxgate magnetometer spin axis offsets from mirror mode observations

Science.gov (United States)

Plaschke, Ferdinand; Narita, Yasuhito

2016-09-01

In-flight calibration of fluxgate magnetometers that are mounted on spacecraft involves finding their outputs in vanishing ambient fields, the so-called magnetometer offsets. If the spacecraft is spin-stabilized, then the spin plane components of these offsets can be relatively easily determined, as they modify the spin tone content in the de-spun magnetic field data. The spin axis offset, however, is more difficult to determine. Therefore, usually Alfvénic fluctuations in the solar wind are used. We propose a novel method to determine the spin axis offset: the mirror mode method. The method is based on the assumption that mirror mode fluctuations are nearly compressible such that the maximum variance direction is aligned to the mean magnetic field. Mirror mode fluctuations are typically found in the Earth's magnetosheath region. We introduce the method and provide a first estimate of its accuracy based on magnetosheath observations by the THEMIS-C spacecraft. We find that 20 h of magnetosheath measurements may already be sufficient to obtain high-accuracy spin axis offsets with uncertainties on the order of a few tenths of a nanotesla, if offset stability can be assumed.

On determining fluxgate magnetometer spin axis offsets from mirror mode observations

Directory of Open Access Journals (Sweden)

F. Plaschke

2016-09-01

Full Text Available In-flight calibration of fluxgate magnetometers that are mounted on spacecraft involves finding their outputs in vanishing ambient fields, the so-called magnetometer offsets. If the spacecraft is spin-stabilized, then the spin plane components of these offsets can be relatively easily determined, as they modify the spin tone content in the de-spun magnetic field data. The spin axis offset, however, is more difficult to determine. Therefore, usually Alfvénic fluctuations in the solar wind are used. We propose a novel method to determine the spin axis offset: the mirror mode method. The method is based on the assumption that mirror mode fluctuations are nearly compressible such that the maximum variance direction is aligned to the mean magnetic field. Mirror mode fluctuations are typically found in the Earth's magnetosheath region. We introduce the method and provide a first estimate of its accuracy based on magnetosheath observations by the THEMIS-C spacecraft. We find that 20 h of magnetosheath measurements may already be sufficient to obtain high-accuracy spin axis offsets with uncertainties on the order of a few tenths of a nanotesla, if offset stability can be assumed.

System of coefficients for charged-particle beam linear transformation by a magnetic dipole element

International Nuclear Information System (INIS)

Tarantin, N.I.

1979-01-01

A new technique for consideration of dipole magnet ion-optical effect has been developed to study the problems of commutation and monochromatization of a charged particle beam. In a new form obtained are systematized coefficients of linear transformation (CLT) of the charged particle beam for radial and axial motions in a magnetic dipole element (MDE) including a dipole magnet and two gaps without magnetic field. Given is a method of graphic determination of MDE parameters and main CLT. The new form of coefficients and conditions of the transformations feasibility considerably facilitates the choice and calculation of dipole elements

Production of field-reversed mirror plasma with a coaxial plasma gun

Science.gov (United States)

Hartman, C.W.; Shearer, J.W.

The use of a coaxial plasma gun to produce a plasma ring which is directed into a magnetic field so as to form a field-reversed plasma confined in a magnetic mirror. Plasma thus produced may be used as a target for subsequent neutral beam injection or other similarly produced and projected plasma rings or for direct fusion energy release in a pulsed mode.

Production of field-reversed mirror plasma with a coaxial plasma gun

International Nuclear Information System (INIS)

Hartman, C.W.; Shearer, J.W.

1982-01-01

The use of a coaxial plasma gun to produce a plasma ring which is directed into a magnetic field so as to form a field-reversed plasma confined in a magnetic mirror. Plasma thus produced may be used as a target for subsequent neutral beam injection or other similarly produced and projected plasma rings or for direct fusion energy release in a pulsed mode

Mirror Neurons in Humans: Consisting or Confounding Evidence?

Science.gov (United States)

Turella, Luca; Pierno, Andrea C.; Tubaldi, Federico; Castiello, Umberto

2009-01-01

The widely known discovery of mirror neurons in macaques shows that premotor and parietal cortical areas are not only involved in executing one's own movement, but are also active when observing the action of others. The goal of this essay is to critically evaluate the substance of functional magnetic resonance imaging (fMRI) and positron emission…

Linear arrangement of nano-scale magnetic particles formed in Cu-Fe-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Kang, Sung, E-mail: k3201s@hotmail.co [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeda, Mahoto [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeguchi, Masaki [Advanced Electron Microscopy Group, National Institute for Materials Science (NIMS), Sakura 3-13, Tsukuba, 305-0047 (Japan); Bae, Dong-Sik [School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam, 641-773 (Korea, Republic of)

2010-04-30

The structural evolution of nano-scale magnetic particles formed in Cu-Fe-Ni alloys on isothermal annealing at 878 K has been investigated by means of transmission electron microscopy (TEM), electron dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS) and field-emission scanning electron microscopy (FE-SEM). Phase decomposition of Cu-Fe-Ni occurred after an as-quenched specimen received a short anneal, and nano-scale magnetic particles were formed randomly in the Cu-rich matrix. A striking feature that two or more nano-scale particles with a cubic shape were aligned linearly along <1,0,0> directions was observed, and the trend was more pronounced at later stages of the precipitation. Large numbers of <1,0,0> linear chains of precipitates extended in three dimensions in late stages of annealing.

Voltage linear transformation circuit design

Science.gov (United States)

Sanchez, Lucas R. W.; Jin, Moon-Seob; Scott, R. Phillip; Luder, Ryan J.; Hart, Michael

2017-09-01

Many engineering projects require automated control of analog voltages over a specified range. We have developed a computer interface comprising custom hardware and MATLAB code to provide real-time control of a Thorlabs adaptive optics (AO) kit. The hardware interface includes an op amp cascade to linearly shift and scale a voltage range. With easy modifications, any linear transformation can be accommodated. In AO applications, the design is suitable to drive a range of different types of deformable and fast steering mirrors (FSM's). Our original motivation and application was to control an Optics in Motion (OIM) FSM which requires the customer to devise a unique interface to supply voltages to the mirror controller to set the mirror's angular deflection. The FSM is in an optical servo loop with a wave front sensor (WFS), which controls the dynamic behavior of the mirror's deflection. The code acquires wavefront data from the WFS and fits a plane, which is subsequently converted into its corresponding angular deflection. The FSM provides +/-3° optical angular deflection for a +/-10 V voltage swing. Voltages are applied to the mirror via a National Instruments digital-to-analog converter (DAC) followed by an op amp cascade circuit. This system has been integrated into our Thorlabs AO testbed which currently runs at 11 Hz, but with planned software upgrades, the system update rate is expected to improve to 500 Hz. To show that the FSM subsystem is ready for this speed, we conducted two different PID tuning runs at different step commands. Once 500 Hz is achieved, we plan to make the code and method for our interface solution freely available to the community.

Design of a magnetic field alignment diagnostic for the MFTF-B magnet system

International Nuclear Information System (INIS)

Deadrick, F.J.; House, P.A.; Frye, R.W.

1985-01-01

Magnet alignment in tandem mirror fusion machines plays a crucial role in achieving and maintaining plasma confinement. Various visual alignment tools have been described by Post et al. to align the Tara magnet system. We have designed and installed a remotely operated magnetic field alignment (MFA) diagnostic system as a part of the Mirror Fusion Test Facility (MFTF-B). It measures critical magnetic field alignment parameters of the MFTF-B coil set while under full-field operating conditions. The MFA diagnostic employs a pair of low-energy, electron beam guns on a remotely positionable probe to trace and map selected magnetic field lines. An array of precision electrical detector paddles locates the position of the electron beam, and thus the magnetic field line, at several critical points. The measurements provide a means to compute proper compensating currents to correct for mechanical misalignments of the magnets with auxiliary trim coils if necessary. This paper describes both the mechanical and electrical design of the MFA diagnostic hardware

Onset of superradiant instabilities in the composed Kerr-black-hole–mirror bomb

Energy Technology Data Exchange (ETDEWEB)

Hod, Shahar [The Ruppin Academic Center, Emeq Hefer 40250 (Israel); The Hadassah Institute, Jerusalem 91010 (Israel)

2014-09-07

It was first pointed out by Press and Teukolsky that a system composed of a spinning Kerr black hole surrounded by a reflecting mirror may develop instabilities. The physical mechanism responsible for the development of these exponentially growing instabilities is the superradiant amplification of bosonic fields confined between the black hole and the mirror. A remarkable feature of this composed black-hole–mirror-field system is the existence of a critical mirror radius, r{sub m}{sup stat}, which supports stationary (marginally-stable) field configurations. This critical (‘stationary’) mirror radius marks the boundary between stable and unstable black-hole–mirror-field configurations: composed systems whose confining mirror is situated in the region r{sub m}mirror is situated in the region r{sub m}>r{sub m}{sup stat} are unstable (that is, there are confined field modes which grow exponentially over time). In the present paper we explore this critical (marginally-stable) boundary between stable and explosive black-hole–mirror-field configurations. It is shown that the innermost (smallest) radius of the confining mirror which allows the extraction of rotational energy from a spinning Kerr black hole approaches the black-hole horizon radius in the extremal limit of rapidly-rotating black holes. We find, in particular, that this critical mirror radius (which marks the onset of superradiant instabilities in the composed system) scales linearly with the black-hole temperature.

Enhanced Plasma Confinement in a Magnetic Well by Whistler Waves

DEFF Research Database (Denmark)

Balmashnov, A. A.; Juul Rasmussen, Jens

1981-01-01

The propagation of whistler waves in a magnetic field of mirror configuration is investigated experimentally. The strong interaction between waves and particles at the electron-cyclotron resonance leads to enhanced confinement in the magnetic well.......The propagation of whistler waves in a magnetic field of mirror configuration is investigated experimentally. The strong interaction between waves and particles at the electron-cyclotron resonance leads to enhanced confinement in the magnetic well....

Design scoping study of the 12T Yin-Yang magnet system for the Tandem Mirror Next Step (TMNS). Final report

International Nuclear Information System (INIS)

1981-09-01

The overall objective of this engineering study was to determine the feasibility of designing a Yin-Yang magnet capable of producing a peak field in the windings of 12T for the Tandem Mirror Next Step (TMNS) program. As part of this technical study, a rough order of magnitude (ROM) cost estimate of the winding for this magnet was undertaken. The preferred approach to the winding design of the TMNS plug coil utilizes innovative design concepts to meet the structural, electrical and thermodynamic requirements of the magnet system. Structurally, the coil is radially partitioned into four sections, preventing the accumulation of the radial loads and reacting them into the structural case. To safely dissipate the 13.34 GJ of energy stored in each Yin-Yang magnet, the winding has been electrically subdivided into parallel or nested coils, each having its own power supply and protection circuitry. This arrangement effectively divides the total stored energy of the coils into manageable subsystems. The windings are cooled with superfluid helium II, operated at 1.8K and 1.2 atmospheres. The superior cooling capabilities of helium II have enabled the overall winding envelope to be minimized, providing a current density of 2367 A/CM 2 , excluding substructure

Design of a transverse-flux permanent-magnet linear generator and controller for use with a free-piston stirling engine

Science.gov (United States)

Zheng, Jigui; Huang, Yuping; Wu, Hongxing; Zheng, Ping

2016-07-01

Transverse-flux with high efficiency has been applied in Stirling engine and permanent magnet synchronous linear generator system, however it is restricted for large application because of low and complex process. A novel type of cylindrical, non-overlapping, transverse-flux, and permanent-magnet linear motor(TFPLM) is investigated, furthermore, a high power factor and less process complexity structure research is developed. The impact of magnetic leakage factor on power factor is discussed, by using the Finite Element Analysis(FEA) model of stirling engine and TFPLM, an optimization method for electro-magnetic design of TFPLM is proposed based on magnetic leakage factor. The relation between power factor and structure parameter is investigated, and a structure parameter optimization method is proposed taking power factor maximum as a goal. At last, the test bench is founded, starting experimental and generating experimental are performed, and a good agreement of simulation and experimental is achieved. The power factor is improved and the process complexity is decreased. This research provides the instruction to design high-power factor permanent-magnet linear generator.

A Monolithic CMOS Magnetic Hall Sensor with High Sensitivity and Linearity Characteristics.

Science.gov (United States)

Huang, Haiyun; Wang, Dejun; Xu, Yue

2015-10-27

This paper presents a fully integrated linear Hall sensor by means of 0.8 μm high voltage complementary metal-oxide semiconductor (CMOS) technology. This monolithic Hall sensor chip features a highly sensitive horizontal switched Hall plate and an efficient signal conditioner using dynamic offset cancellation technique. An improved cross-like Hall plate achieves high magnetic sensitivity and low offset. A new spinning current modulator stabilizes the quiescent output voltage and improves the reliability of the signal conditioner. The tested results show that at the 5 V supply voltage, the maximum Hall output voltage of the monolithic Hall sensor microsystem, is up to ±2.1 V and the linearity of Hall output voltage is higher than 99% in the magnetic flux density range from ±5 mT to ±175 mT. The output equivalent residual offset is 0.48 mT and the static power consumption is 20 mW.

A Monolithic CMOS Magnetic Hall Sensor with High Sensitivity and Linearity Characteristics

Directory of Open Access Journals (Sweden)

Haiyun Huang

2015-10-01

Full Text Available This paper presents a fully integrated linear Hall sensor by means of 0.8 μm high voltage complementary metal-oxide semiconductor (CMOS technology. This monolithic Hall sensor chip features a highly sensitive horizontal switched Hall plate and an efficient signal conditioner using dynamic offset cancellation technique. An improved cross-like Hall plate achieves high magnetic sensitivity and low offset. A new spinning current modulator stabilizes the quiescent output voltage and improves the reliability of the signal conditioner. The tested results show that at the 5 V supply voltage, the maximum Hall output voltage of the monolithic Hall sensor microsystem, is up to ±2.1 V and the linearity of Hall output voltage is higher than 99% in the magnetic flux density range from ±5 mT to ±175 mT. The output equivalent residual offset is 0.48 mT and the static power consumption is 20 mW.

Einstein's Mirror

Science.gov (United States)

Gjurchinovski, Aleksandar; Skeparovski, Aleksandar

2008-01-01

Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity. The problem was first investigated by Einstein in his famous 1905 paper by using the Lorentz transformations to switch from the mirror's rest frame to the frame where the mirror moves at a…

Magnetic field modification of optical magnetic dipoles.

Science.gov (United States)

Armelles, Gaspar; Caballero, Blanca; Cebollada, Alfonso; Garcia-Martin, Antonio; Meneses-Rodríguez, David

2015-03-11

Acting on optical magnetic dipoles opens novel routes to govern light-matter interaction. We demonstrate magnetic field modification of the magnetic dipolar moment characteristic of resonant nanoholes in thin magnetoplasmonic films. This is experimentally shown through the demonstration of the magneto-optical analogue of Babinet's principle, where mirror imaged MO spectral dependencies are obtained for two complementary magnetoplasmonic systems: holes in a perforated metallic layer and a layer of disks on a substrate.

Experimental study and analytical model of deformation of magnetostrictive films as applied to mirrors for x-ray space telescopes.

Science.gov (United States)

Wang, Xiaoli; Knapp, Peter; Vaynman, S; Graham, M E; Cao, Jian; Ulmer, M P

2014-09-20

The desire for continuously gaining new knowledge in astronomy has pushed the frontier of engineering methods to deliver lighter, thinner, higher quality mirrors at an affordable cost for use in an x-ray observatory. To address these needs, we have been investigating the application of magnetic smart materials (MSMs) deposited as a thin film on mirror substrates. MSMs have some interesting properties that make the application of MSMs to mirror substrates a promising solution for making the next generation of x-ray telescopes. Due to the ability to hold a shape with an impressed permanent magnetic field, MSMs have the potential to be the method used to make light weight, affordable x-ray telescope mirrors. This paper presents the experimental setup for measuring the deformation of the magnetostrictive bimorph specimens under an applied magnetic field, and the analytical and numerical analysis of the deformation. As a first step in the development of tools to predict deflections, we deposited Terfenol-D on the glass substrates. We then made measurements that were compared with the results from the analytical and numerical analysis. The surface profiles of thin-film specimens were measured under an external magnetic field with white light interferometry (WLI). The analytical model provides good predictions of film deformation behavior under various magnetic field strengths. This work establishes a solid foundation for further research to analyze the full three-dimensional deformation behavior of magnetostrictive thin films.

Control of first-wall surface conditions in the 2XIIB Magnetic Mirror Plasma Confinement experiment

International Nuclear Information System (INIS)

Simonen, T.C.; Bulmer, R.H.; Coensgen, F.H.

1976-01-01

The control of first-wall surface conditions in the 2XIIB Magnetic Mirror Plasma Confinement experiment is described. Before each plasma shot, the first wall is covered with a freshly gettered titanium surface. Up to 5 MW of neutral beam power has been injected into 2XIIB, resulting in first-wall bombardment fluxes of 10 17 atoms . cm -2 . s -1 of 13-keV mean energy deuterium atoms for several ms. The background gas flux is measured with a calibrated, 11-channel, fast-atom detector. Background gas levels are found to depend on surface conditions, injected beam current, and beam pulse duration. For our best operating conditions, an efective reflex coefficient of 0.3 can be inferred from the measurements. Experiments with long-duration and high-current beam injection are limited by charge exchange; however, experiments with shorter beam duration are not limited by first-wall surface conditions. It is concluded that surface effects will be reduced further with smoother walls. (Auth.)

Preparation and Characterization of Silver Liquid Thin Films for Magnetic Fluid Deformable Mirror

Directory of Open Access Journals (Sweden)

Lianchao Zhang

2015-01-01

Full Text Available Silver liquid thin film, formed by silver nanoparticles stacking and spreading on the surface of the liquid, is one of the important parts of magnetic fluid deformable mirror. First, silver nanoparticles were prepared by liquid phase chemical reduction method using sodium citrate as reducing agent and stabilizer and silver nitrate as precursor. Characterization of silver nanoparticles was studied using X-ray diffractometer, UV-vis spectrophotometer, and transmission electron microscope (TEM. The results showed that silver nanoparticles are spherical and have a good monodispersity. Additionally, the effect of the reaction conditions on the particle size of silver is obvious. And then silver liquid thin films were prepared by oil-water two-phase interface technology using as-synthesized silver nanoparticles. Properties of the film were investigated using different technology. The results showed that the film has good reflectivity and the particle size has a great influence on the reflectivity of the films. SEM photos showed that the liquid film is composed of multilayer silver nanoparticles. In addition, stability of the film was studied. The results showed that after being stored for 8 days under natural conditions, the gloss and reflectivity of the film start to decrease.

Einstein's Mirror

Science.gov (United States)

Gjurchinovski, Aleksandar; Skeparovski, Aleksandar

2008-10-01

Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity.1-4 The problem was first investigated by Einstein in his famous 1905 paper by using the Lorentz transformations to switch from the mirror's rest frame to the frame where the mirror moves at a constant velocity.5 Einstein showed an intriguing fact that the usual law of reflection would not hold in the case of a uniformly moving mirror, that is, the angles of incidence and reflection of the light would not equal each other. Later on, it has been shown that the law of reflection at a moving mirror can be obtained in various alternative ways,6-10 but none of them seems suitable for bringing this interesting subject into the high school classroom.

Torque decomposition and control in an iron core linear permanent magnet motor.

NARCIS (Netherlands)

Overboom, T.T.; Smeets, J.P.C.; Stassen, J.M.; Jansen, J.W.; Lomonova, E.

2012-01-01

Abstract—This paper concerns the decomposition and control of the torque produced by an iron core linear permanent magnet motor. The proposed method is based on the dq0-decomposition of the three-phase currents using Park’s transformation. The torque is decomposed into a reluctance component and two

Plasma cleaning of ITER first mirrors

Science.gov (United States)

Moser, L.; Marot, L.; Steiner, R.; Reichle, R.; Leipold, F.; Vorpahl, C.; Le Guern, F.; Walach, U.; Alberti, S.; Furno, I.; Yan, R.; Peng, J.; Ben Yaala, M.; Meyer, E.

2017-12-01

Nuclear fusion is an extremely attractive option for future generations to compete with the strong increase in energy consumption. Proper control of the fusion plasma is mandatory to reach the ambitious objectives set while preserving the machine’s integrity, which requests a large number of plasma diagnostic systems. Due to the large neutron flux expected in the International Thermonuclear Experimental Reactor (ITER), regular windows or fibre optics are unusable and were replaced by so-called metallic first mirrors (FMs) embedded in the neutron shielding, forming an optical labyrinth. Materials eroded from the first wall reactor through physical or chemical sputtering will migrate and will be deposited onto mirrors. Mirrors subject to net deposition will suffer from reflectivity losses due to the deposition of impurities. Cleaning systems of metallic FMs are required in more than 20 optical diagnostic systems in ITER. Plasma cleaning using radio frequency (RF) generated plasmas is currently being considered the most promising in situ cleaning technique. An update of recent results obtained with this technique will be presented. These include the demonstration of cleaning of several deposit types (beryllium, tungsten and beryllium proxy, i.e. aluminium) at 13.56 or 60 MHz as well as large scale cleaning (mirror size: 200 × 300 mm2). Tests under a strong magnetic field up to 3.5 T in laboratory and first experiments of RF plasma cleaning in EAST tokamak will also be discussed. A specific focus will be given on repetitive cleaning experiments performed on several FM material candidates.

Global monodromy modulo 5 of quintic-mirror family

OpenAIRE

Shirakawa, Kennichiro

2011-01-01

The quintic-mirror family is a well-known one-parameter family of Calabi-Yau threefolds. A complete description of the global monodromy group of this family is not yet known. In this paper, we give a presentation of the global monodromy group in the general linear group of degree 4 over the ring of integers modulo 5.

Nu shifts in betatron oscillations from uniform perturbations in the presence of non-linear magnetic guide fields

International Nuclear Information System (INIS)

Crebbin, K.C.

1985-05-01

Uniform magnetic field perturbations cause a closed orbit distortion in a circular accelerator. If the magnetic guide field is non-linear these perturbations can also cause a Nu shift in the betatron oscillations. Such a shift in radial Nu values has been observed in the Bevalac while studying the low energy resonant extraction system. In the Bevalac, the radial perturbation comes from the quadrants being magnetically about 0.8% longer than 90 0 . The normal effect of this type of perturbation is a radial closed orbit shift and orbit distortion. The Nu shift, associated with this type of perturbation in the presence of a non-linear guide field, is discussed in this paper. A method of handling the non-linear n values is discussed as well as the mechanism for the associated Nu shift. Computer calculations are compared to measurements. 2 refs., 4 figs

A novel single-phase flux-switching permanent magnet linear generator used for free-piston Stirling engine

Science.gov (United States)

Zheng, Ping; Sui, Yi; Tong, Chengde; Bai, Jingang; Yu, Bin; Lin, Fei

2014-05-01

This paper investigates a novel single-phase flux-switching permanent-magnet (PM) linear machine used for free-piston Stirling engines. The machine topology and operating principle are studied. A flux-switching PM linear machine is designed based on the quasi-sinusoidal speed characteristic of the resonant piston. Considering the performance of back electromotive force and thrust capability, some leading structural parameters, including the air gap length, the PM thickness, the ratio of the outer radius of mover to that of stator, the mover tooth width, the stator tooth width, etc., are optimized by finite element analysis. Compared with conventional three-phase moving-magnet linear machine, the proposed single-phase flux-switching topology shows advantages in less PM use, lighter mover, and higher volume power density.

Fastest Rates for Stochastic Mirror Descent Methods

KAUST Repository

Hanzely, Filip; Richtarik, Peter

2018-01-01

Relative smoothness - a notion introduced by Birnbaum et al. (2011) and rediscovered by Bauschke et al. (2016) and Lu et al. (2016) - generalizes the standard notion of smoothness typically used in the analysis of gradient type methods. In this work we are taking ideas from well studied field of stochastic convex optimization and using them in order to obtain faster algorithms for minimizing relatively smooth functions. We propose and analyze two new algorithms: Relative Randomized Coordinate Descent (relRCD) and Relative Stochastic Gradient Descent (relSGD), both generalizing famous algorithms in the standard smooth setting. The methods we propose can be in fact seen as a particular instances of stochastic mirror descent algorithms. One of them, relRCD corresponds to the first stochastic variant of mirror descent algorithm with linear convergence rate.

Fastest Rates for Stochastic Mirror Descent Methods

KAUST Repository

Hanzely, Filip

2018-03-20

Relative smoothness - a notion introduced by Birnbaum et al. (2011) and rediscovered by Bauschke et al. (2016) and Lu et al. (2016) - generalizes the standard notion of smoothness typically used in the analysis of gradient type methods. In this work we are taking ideas from well studied field of stochastic convex optimization and using them in order to obtain faster algorithms for minimizing relatively smooth functions. We propose and analyze two new algorithms: Relative Randomized Coordinate Descent (relRCD) and Relative Stochastic Gradient Descent (relSGD), both generalizing famous algorithms in the standard smooth setting. The methods we propose can be in fact seen as a particular instances of stochastic mirror descent algorithms. One of them, relRCD corresponds to the first stochastic variant of mirror descent algorithm with linear convergence rate.

Moving-ring field-reversed mirror reactor

International Nuclear Information System (INIS)

Smith, A.C. Jr.; Ashworth, C.P.; Abreu, K.E.

1981-01-01

We describe a first prototype fusion reactor design of the Moving-Ring Field-Reversed Mirror Reactor. The fusion fuel is confined in current-carrying rings of magnetically-field-reversed plasma. The plamsa rings, formed by a coaxial plasma gun, are magnetically compressed to ignition temperature while they are being injected into the reactor's burner section. DT ice pellets refuel the rings during the burn at a rate which maintains constant fusion power. A steady train of plasma rings moves at constant speed through the reactor under the influence of a slightly diverging magnetic field. The aluminum first wall and breeding zone structure minimize induced radioactivity; hands-on maintenance is possible on reactor components outside the breeding blanket. Helium removes the heat from the Li 2 O tritium breeding blanket and is used to generate steam. The reactor produces a constant, net power of 376 MW

Amorphous Metals and Composites as Mirrors and Mirror Assemblies

Science.gov (United States)

Hofmann, Douglas C. (Inventor); Davis, Gregory L. (Inventor); Agnes, Gregory S. (Inventor); Shapiro, Andrew A. (Inventor)

2016-01-01

A mirror or mirror assembly fabricated by molding, pressing, assembling, or depositing one or more bulk metal glass (BMG), bulk metal glass composite (BMGMC), or amorphous metal (AM) parts and where the optical surface and backing of the mirror can be fabricated without machining or polishing by utilizing the unique molding capabilities of this class of materials.

Mirror machine reactors

International Nuclear Information System (INIS)

Carlson, G.A.; Moir, R.W.

1976-01-01

Recent mirror reactor conceptual design studies are described. Considered in detail is the design of ''standard'' Yin-Yang fusion power reactors with classical and enhanced confinement. It is shown that to be economically competitive with estimates for other future energy sources, mirror reactors require a considerable increase in Q, or major design simplifications, or preferably both. These improvements may require a departure from the ''standard'' configuration. Two attractive possibilities, both of which would use much of the same physics and technology as the ''standard'' mirror, are the field reversed mirror and the end-stoppered mirror

Investigation of a tubular dual-stator flux-switching permanent-magnet linear generator for free-piston energy converter

Science.gov (United States)

Sui, Yi; Zheng, Ping; Tong, Chengde; Yu, Bin; Zhu, Shaohong; Zhu, Jianguo

2015-05-01

This paper describes a tubular dual-stator flux-switching permanent-magnet (PM) linear generator for free-piston energy converter. The operating principle, topology, and design considerations of the machine are investigated. Combining the motion characteristic of free-piston Stirling engine, a tubular dual-stator PM linear generator is designed by finite element method. Some major structural parameters, such as the outer and inner radii of the mover, PM thickness, mover tooth width, tooth width of the outer and inner stators, etc., are optimized to improve the machine performances like thrust capability and power density. In comparison with conventional single-stator PM machines like moving-magnet linear machine and flux-switching linear machine, the proposed dual-stator flux-switching PM machine shows advantages in higher mass power density, higher volume power density, and lighter mover.

MODELING OF EQUIVALENT STIFFNESS OF A MAGNETIC SPRING OF VIBRATION EXCITER BASED ON COAXIAL-LINEAR MOTOR

Directory of Open Access Journals (Sweden)

G.M. Golenkov

2015-12-01

Full Text Available Purpose. The research of the influence of value and direction of current on the equivalent spring magnetic force based on coaxial-linear motor (CLM – MS. Methodology. We carried out investigation of the equivalent harshness of magnetic spring with determination of electromechanical propulsion performance characteristics by the methods of computer modeling and experimental research of physical model of CLM – MS. The modeling of magnetic spring of CLM – MS is carried out by the finite-element method. The challenge is met as an axisymmetric challenge in cylindrical co-ordinates in magnetostatic approach. The experimental investigattion of the propulsion performance characteristics of magnetic spring is carried out on the test bench. Results. After the computer modeling and the experimental investigation of the electromechanical propulsion performance characteristics of magnetic spring the expressions of equivalent stiffness coefficient depending on the current in winding are obtained. The results of computer modeling are confirmed experimentally. Originality. The determination of equivalent stiffness coefficient of magnetic spring of vibration exciter based on coaxial-linear motor. Practical value. The obtained determination of equivalent stiffness coefficient of magnetic spring may be used in process of designing of vibration machines with devices for change of natural oscillation frequency.

Classical mirror symmetry

CERN Document Server

Jinzenji, Masao

2018-01-01

This book furnishes a brief introduction to classical mirror symmetry, a term that denotes the process of computing Gromov–Witten invariants of a Calabi–Yau threefold by using the Picard–Fuchs differential equation of period integrals of its mirror Calabi–Yau threefold. The book concentrates on the best-known example, the quintic hypersurface in 4-dimensional projective space, and its mirror manifold. First, there is a brief review of the process of discovery of mirror symmetry and the striking result proposed in the celebrated paper by Candelas and his collaborators. Next, some elementary results of complex manifolds and Chern classes needed for study of mirror symmetry are explained. Then the topological sigma models, the A-model and the B-model, are introduced. The classical mirror symmetry hypothesis is explained as the equivalence between the correlation function of the A-model of a quintic hyper-surface and that of the B-model of its mirror manifold. On the B-model side, the process of construct...

Hot electron plasma equilibrium and stability in the Constance B mirror experiment

International Nuclear Information System (INIS)

Chen, Xing.

1988-04-01

An experimental study of the equilibrium and macroscopic stability property of an electron cyclotron resonance heating (ECRH) generated plasma in a minimum-B mirror is presented. The Constance B mirror is a single cell quadrupole magnetic mirror in which high beta (β ≤ 0.3) hot electron plasmas (T/sub e/≅400 keV) are created with up to 4 kW of ECRH power. The plasma equilibrium profile is hollow and resembles the baseball seam geometry of the magnet which provides the confining magnetic field. This configuration coincides with the drift orbit of deeply trapped particles. The on-axis hollowness of the hot electron density profile is 50 /+-/ 10%, and the pressure profile is at least as hollow as, if not more than, the hot electron density profile. The hollow plasma equilibrium is macroscopically stable and generated in all the experimental conditions in which the machine has been operated. Small macroscopic plasma fluctuations in the range of the hot electron curvature drift frequency sometimes occur but their growth rate is small (ω/sub i//ω/sub r/ ≤ 10 -2 ) and saturate at very low level (δB//bar B/ ≤ 10 -3 ). Particle drift reversal is predicted to occur for the model pressure profile which best fits the experimental data under the typical operating conditions. No strong instability is observed when the plasma is near the drift reversal parameter regime, despite a theoretical prediction of instability under such conditions. The experiment shows that the cold electron population has no stabilizing effect to the hot electrons, which disagrees with current hot electron stability theories and results of previous maximum-B experiments. A theoretical analysis using MHD theory shows that the compressibility can stabilize a plasma with a hollowness of 20--30% in the Constance B mirror well. 57 refs

Transition metal modified bulk BiFeO3 with improved magnetization and linear magneto-electric coupling

International Nuclear Information System (INIS)

Puli, Venkata Sreenivas; Kumar, A.; Panwar, N.; Panwar, I.C.; Katiyar, R.S.

2011-01-01

Highlights: → Present composition (Bi 0.9 Sm 0.10 Fe 0.95 Co 0.05 O 3 (BSFCO) have shown very high magnetization compared to parent BFO. → The magnetic hysteresis loops are well saturated with high saturation magnetization 2.89 emu/gm (unpoled and unleached) and 2.18 emu/gm (poled and unleached) respectively. → Converse ME coupling were found 0.8e-10 s m -1 (H||E) and 0.6-0.8 x 10 -10 s m -1 (H-perpendicular E) which are better than the single phase multiferroic obeying linear ME coupling. - Abstract: At present BiFeO 3 (BFO) is the most attractive and sole example, which possesses low magnetization value, high leakage current and low polarization in ceramic form. Single-phase room temperature multiferroics are rare in nature. This paper deals with the improved magnetic and observed linear magneto-electric coupling in Co and Sm co-doped BiFeO 3 ceramics synthesized by sol-gel process at low temperature ∼600 deg. C. As synthesized Bi 0.9 Sm 0.10 Fe 0.95 Co 0.05 O 3 (BSFCO) showed high impurities phases (20%) over wide range of calcination temperatures. Impurity phases reduced drastically from 20% to 5% after leaching with nitric acid. However the electrical and the magnetic properties were almost the same for both phases. Well-defined magnetic hysteresis with high magnetic moment was found at room temperature. Ferroelectric polarization studies demonstrated similar values and shape as reported in literature for the pure bulk BFO. Linear magneto-electric (ME) coupling and weak ME coefficient (α) ∼ 0.6 e-10 s m -1 were observed in the co-doped BFO. The origin of the strong ferromagnetic property in our samples may be due to the presence of rare earth and transition metal ions at the lattice sites of BFO or due to impurity phase, since we have not seen any change in magnetization with reduction of impurity phase the later effect is more unlikely.

Upper extremity rehabilitation of stroke: Facilitation of corticospinal excitability using virtual mirror paradigm

Directory of Open Access Journals (Sweden)

Kang Youn

2012-10-01

Full Text Available Abstract Background Several experimental studies in stroke patients suggest that mirror therapy and various virtual reality programs facilitate motor rehabilitation. However, the underlying mechanisms for these therapeutic effects have not been previously described. Objectives We attempted to delineate the changes in corticospinal excitability when individuals were asked to exercise their upper extremity using a real mirror and virtual mirror. Moreover, we attempted to delineate the role of visual modulation within the virtual environment that affected corticospinal excitability in healthy subjects and stroke patients. Methods A total of 18 healthy subjects and 18 hemiplegic patients were enrolled into the study. Motor evoked potential (MEPs from transcranial magnetic stimulation were recorded in the flexor carpi radialis of the non-dominant or affected upper extremity using three different conditions: (A relaxation; (B real mirror; and (C virtual mirror. Moreover, we compared the MEPs from the virtual mirror paradigm using continuous visual feedback or intermittent visual feedback. Results The rates of amplitude increment and latency decrement of MEPs in both groups were higher during the virtual mirror task than during the real mirror. In healthy subjects and stroke patients, the virtual mirror task with intermittent visual feedback significantly facilitated corticospinal excitability of MEPs compared with continuous visual feedback. Conclusion Corticospinal excitability was facilitated to a greater extent in the virtual mirror paradigm than in the real mirror and in intermittent visual feedback than in the continuous visual feedback, in both groups. This provides neurophysiological evidence supporting the application of the virtual mirror paradigm using various visual modulation technologies to upper extremity rehabilitation in stroke patients.

Construction and operational experience of the Tandem Mirror Experiment-Upgrade (TMX-U)

International Nuclear Information System (INIS)

Chargin, A.K.; Calderon, M.O.; Moore, T.L.

1983-01-01

The Tandem Mirror Experiment-Upgrade (TMX-U) incorporates two new features at Lawrence Livermore National Laboratory (LLNL) tandem mirror program, thermal barriers in the end plugs and injection of the neutral beams at several oblique angles. The thermal barriers isolate the electrons in the end plugs from those in the central cell, making it possible to heat them independently with microwaves. In addition, this innovation produces a large potential gradient in the end plugs with lower magnetic fields and lower neutral-beam energies than would be possible in a conventional tandem mirror device. The TMX-U is also designed to test neutral-beam-injection angles as an experimental parameter. We use angles other than 90 0 to produce a plasma with improved microstability

Linear response theory for magnetic Schrodinger operators in disordered media

CERN Document Server

Bouclet, J M; Klein, A; Schenker, J

2004-01-01

We justify the linear response theory for an ergodic Schrodinger operator with magnetic field within the non-interacting particle approximation, and derive a Kubo formula for the electric conductivity tensor. To achieve that, we construct suitable normed spaces of measurable covariant operators where the Liouville equation can be solved uniquely. If the Fermi level falls into a region of localization, we recover the well-known Kubo-Streda formula for the quantum Hall conductivity at zero temperature.

Applying alpha-channeling to mirror machines

Energy Technology Data Exchange (ETDEWEB)

Zhmoginov, A. I.; Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States)

2012-05-15

The {alpha}-channeling effect entails the use of radio-frequency waves to expel and cool high-energetic {alpha} particles born in a fusion reactor; the device reactivity can then be increased even further by redirecting the extracted energy to fuel ions. Originally proposed for tokamaks, this technique has also been shown to benefit open-ended fusion devices. Here, the fundamental theory and practical aspects of {alpha} channeling in mirror machines are reviewed, including the influence of magnetic field inhomogeneity and the effect of a finite wave region on the {alpha}-channeling mechanism. For practical implementation of the {alpha}-channeling effect in mirror geometry, suitable contained weakly damped modes are identified. In addition, the parameter space of candidate waves for implementing the {alpha}-channeling effect can be significantly extended through the introduction of a suitable minority ion species that has the catalytic effect of moderating the transfer of power from the {alpha}-channeling wave to the fuel ions.

Mirror symmetry

CERN Document Server

Voisin, Claire

1999-01-01

This is the English translation of Professor Voisin's book reflecting the discovery of the mirror symmetry phenomenon. The first chapter is devoted to the geometry of Calabi-Yau manifolds, and the second describes, as motivation, the ideas from quantum field theory that led to the discovery of mirror symmetry. The other chapters deal with more specialized aspects of the subject: the work of Candelas, de la Ossa, Greene, and Parkes, based on the fact that under the mirror symmetry hypothesis, the variation of Hodge structure of a Calabi-Yau threefold determines the Gromov-Witten invariants of its mirror; Batyrev's construction, which exhibits the mirror symmetry phenomenon between hypersurfaces of toric Fano varieties, after a combinatorial classification of the latter; the mathematical construction of the Gromov-Witten potential, and the proof of its crucial property (that it satisfies the WDVV equation), which makes it possible to construct a flat connection underlying a variation of Hodge structure in the ...

Design rules for a compact and low-cost optical position sensing of MOEMS tilt mirrors based on a Gaussian-shaped light source

Science.gov (United States)

Baumgart, Marcus; Tortschanoff, Andreas

2013-05-01

A tilt mirror's deflection angle tracking setup is examined from a theoretical point of view. The proposed setup is based on a simple optical approach and easily scalable. Thus, the principle is especially of interest for small and fast oscillating MEMS/MOEMS based tilt mirrors. An experimentally established optical scheme is used as a starting point for accurate and fast mirror angle-position detection. This approach uses an additional layer, positioned under the MOEMS mirror's backside, consisting of a light source in the center and two photodetectors positioned symmetrical around the center. The mirror's back surface is illuminated by the light source and the intensity change due to mirror tilting is tracked via the photodiodes. The challenge of this method is to get a linear relation between the measured intensity and the current mirror tilt angle even for larger angles. State-of-the-art MOEMS mirrors achieve angles up to ±30°, which exceeds the linear angle approximations. The use of an LED, small laser diode or VCSEL as a lightsource is appropriate due to their small size and inexpensive price. Those light sources typically emit light with a Gaussian intensity distribution. This makes an analytical prediction of the expected detector signal quite complicated. In this publication an analytical simulation model is developed to evaluate the influence of the main parameters for this optical mirror tilt-sensor design. An easy and fast to calculate value directly linked to the mirror's tilt-angle is the "relative differential intensity" (RDI = (I1 - I2) / (I1 + I2)). Evaluation of its slope and nonlinear error highlights dependencies between the identified parameters for best SNR and linearity. Also the energy amount covering the detector area is taken into account. Design optimizing rules are proposed and discussed based on theoretical considerations.

Statistical analysis of mirror mode waves in sheath regions driven by interplanetary coronal mass ejection

Science.gov (United States)

Ala-Lahti, Matti M.; Kilpua, Emilia K. J.; Dimmock, Andrew P.; Osmane, Adnane; Pulkkinen, Tuija; Souček, Jan

2018-05-01

We present a comprehensive statistical analysis of mirror mode waves and the properties of their plasma surroundings in sheath regions driven by interplanetary coronal mass ejection (ICME). We have constructed a semi-automated method to identify mirror modes from the magnetic field data. We analyze 91 ICME sheath regions from January 1997 to April 2015 using data from the Wind spacecraft. The results imply that similarly to planetary magnetosheaths, mirror modes are also common structures in ICME sheaths. However, they occur almost exclusively as dip-like structures and in mirror stable plasma. We observe mirror modes throughout the sheath, from the bow shock to the ICME leading edge, but their amplitudes are largest closest to the shock. We also find that the shock strength (measured by Alfvén Mach number) is the most important parameter in controlling the occurrence of mirror modes. Our findings suggest that in ICME sheaths the dominant source of free energy for mirror mode generation is the shock compression. We also suggest that mirror modes that are found deeper in the sheath are remnants from earlier times of the sheath evolution, generated also in the vicinity of the shock.

Pole-shape optimization of permanent-magnet linear synchronous motor for reduction of thrust ripple

Energy Technology Data Exchange (ETDEWEB)

Tavana, Nariman Roshandel, E-mail: nroshandel@ee.iust.ac.i [Department of Electrical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Shoulaie, Abbas, E-mail: shoulaie@iust.ac.i [Department of Electrical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of)

2011-01-15

In this paper, we have used magnet arc shaping technique in order to improve the performance of permanent-magnet linear synchronous motor (PMLSM). At first, a detailed analytical modeling based on Maxwell equations is presented for the analysis and design of PMLSM with the arc-shaped magnetic poles (ASMPs). Then the accuracy of presented method is verified by finite-element method. Very close agreement between the analytical and finite-element results shows the effectiveness of the proposed method. Finally, a magnet shape design is carried out based on the analytical method to enhance the motor developed thrust. Pertinent evaluations on the optimal design performance demonstrate that shape optimization leads to a design with extra low thrust ripple.

Pole-shape optimization of permanent-magnet linear synchronous motor for reduction of thrust ripple

International Nuclear Information System (INIS)

Tavana, Nariman Roshandel; Shoulaie, Abbas

2011-01-01

In this paper, we have used magnet arc shaping technique in order to improve the performance of permanent-magnet linear synchronous motor (PMLSM). At first, a detailed analytical modeling based on Maxwell equations is presented for the analysis and design of PMLSM with the arc-shaped magnetic poles (ASMPs). Then the accuracy of presented method is verified by finite-element method. Very close agreement between the analytical and finite-element results shows the effectiveness of the proposed method. Finally, a magnet shape design is carried out based on the analytical method to enhance the motor developed thrust. Pertinent evaluations on the optimal design performance demonstrate that shape optimization leads to a design with extra low thrust ripple.

TU-H-BRA-02: The Physics of Magnetic Field Isolation in a Novel Compact Linear Accelerator Based MRI-Guided Radiation Therapy System

Energy Technology Data Exchange (ETDEWEB)

Low, D [UCLA, Los Angeles, CA (United States); Mutic, S [Washington University School of Medicine, Saint Louis, MO (United States); Shvartsman, S; Chmielewski, T; Fought, G; Sharma, A; Dempsey, J [ViewRay, Inc., Oakwood Village, OH (United States)

2016-06-15

Purpose: To develop a method for isolating the MRI magnetic field from field-sensitive linear accelerator components at distances close to isocenter. Methods: A MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. In order to accomplish this, the magnetron, port circulator, radiofrequency waveguide, gun driver, and linear accelerator needed to be placed in locations with low magnetic fields. The system was also required to be compact, so moving these components far from the main magnetic field and isocenter was not an option. The magnetic field sensitive components (exclusive of the waveguide) were placed in coaxial steel sleeves that were electrically and mechanically isolated and whose thickness and placement were optimized using E&M modeling software. Six sets of sleeves were placed 60° apart, 85 cm from isocenter. The Faraday effect occurs when the direction of propagation is parallel to the magnetic RF field component, rotating the RF polarization, subsequently diminishing RF power. The Faraday effect was avoided by orienting the waveguides such that the magnetic field RF component was parallel to the magnetic field. Results: The magnetic field within the shields was measured to be less than 40 Gauss, significantly below the amount needed for the magnetron and port circulator. Additional mu-metal was employed to reduce the magnetic field at the linear accelerator to less than 1 Gauss. The orientation of the RF waveguides allowed the RT transport with minimal loss and reflection. Conclusion: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of creating low magnetic field environments for the magnetic-field sensitive components, has been solved. The measured magnetic fields are sufficiently small to enable system integration. This work supported by ViewRay, Inc.

TU-H-BRA-02: The Physics of Magnetic Field Isolation in a Novel Compact Linear Accelerator Based MRI-Guided Radiation Therapy System

International Nuclear Information System (INIS)

Low, D; Mutic, S; Shvartsman, S; Chmielewski, T; Fought, G; Sharma, A; Dempsey, J

2016-01-01

Purpose: To develop a method for isolating the MRI magnetic field from field-sensitive linear accelerator components at distances close to isocenter. Methods: A MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. In order to accomplish this, the magnetron, port circulator, radiofrequency waveguide, gun driver, and linear accelerator needed to be placed in locations with low magnetic fields. The system was also required to be compact, so moving these components far from the main magnetic field and isocenter was not an option. The magnetic field sensitive components (exclusive of the waveguide) were placed in coaxial steel sleeves that were electrically and mechanically isolated and whose thickness and placement were optimized using E&M modeling software. Six sets of sleeves were placed 60° apart, 85 cm from isocenter. The Faraday effect occurs when the direction of propagation is parallel to the magnetic RF field component, rotating the RF polarization, subsequently diminishing RF power. The Faraday effect was avoided by orienting the waveguides such that the magnetic field RF component was parallel to the magnetic field. Results: The magnetic field within the shields was measured to be less than 40 Gauss, significantly below the amount needed for the magnetron and port circulator. Additional mu-metal was employed to reduce the magnetic field at the linear accelerator to less than 1 Gauss. The orientation of the RF waveguides allowed the RT transport with minimal loss and reflection. Conclusion: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of creating low magnetic field environments for the magnetic-field sensitive components, has been solved. The measured magnetic fields are sufficiently small to enable system integration. This work supported by ViewRay, Inc.

Magnetic corrections to π -π scattering lengths in the linear sigma model

Science.gov (United States)

Loewe, M.; Monje, L.; Zamora, R.

2018-03-01

In this article, we consider the magnetic corrections to π -π scattering lengths in the frame of the linear sigma model. For this, we consider all the one-loop corrections in the s , t , and u channels, associated to the insertion of a Schwinger propagator for charged pions, working in the region of small values of the magnetic field. Our calculation relies on an appropriate expansion for the propagator. It turns out that the leading scattering length, l =0 in the S channel, increases for an increasing value of the magnetic field, in the isospin I =2 case, whereas the opposite effect is found for the I =0 case. The isospin symmetry is valid because the insertion of the magnetic field occurs through the absolute value of the electric charges. The channel I =1 does not receive any corrections. These results, for the channels I =0 and I =2 , are opposite with respect to the thermal corrections found previously in the literature.

[Motion control of moving mirror based on fixed-mirror adjustment in FTIR spectrometer].

Science.gov (United States)

Li, Zhong-bing; Xu, Xian-ze; Le, Yi; Xu, Feng-qiu; Li, Jun-wei

2012-08-01

The performance of the uniform motion of the moving mirror, which is the only constant motion part in FTIR spectrometer, and the performance of the alignment of the fixed mirror play a key role in FTIR spectrometer, and affect the interference effect and the quality of the spectrogram and may restrict the precision and resolution of the instrument directly. The present article focuses on the research on the uniform motion of the moving mirror and the alignment of the fixed mirror. In order to improve the FTIR spectrometer, the maglev support system was designed for the moving mirror and the phase detection technology was adopted to adjust the tilt angle between the moving mirror and the fixed mirror. This paper also introduces an improved fuzzy PID control algorithm to get the accurate speed of the moving mirror and realize the control strategy from both hardware design and algorithm. The results show that the development of the moving mirror motion control system gets sufficient accuracy and real-time, which can ensure the uniform motion of the moving mirror and the alignment of the fixed mirror.

A Non-Linear Force-Free Field Model for the Evolving Magnetic Structure of Solar Filaments

Science.gov (United States)

Mackay, Duncan H.; van Ballegooijen, A. A.

2009-12-01

In this paper the effect of a small magnetic element approaching the main body of a solar filament is considered through non-linear force-free field modeling. The filament is represented by a series of magnetic dips. Once the dips are calculated, a simple hydrostatic atmosphere model is applied to determine which structures have sufficient column mass depth to be visible in Hα. Two orientations of the bipole are considered, either parallel or anti-parallel to the overlying arcade. The magnetic polarity that lies closest to the filament is then advected towards the filament. Initially for both the dominant and minority polarity advected elements, right/left bearing barbs are produced for dextral/sinsitral filaments. The production of barbs due to dominant polarity elements is a new feature. In later stages the filament breaks into two dipped sections and takes a highly irregular, non-symmetrical form with multiple pillars. The two sections are connected by field lines with double dips even though the twist of the field is less than one turn. Reconnection is not found to play a key role in the break up of the filament. The non-linear force-free fields produce very different results to extrapolated linear-force free fields. For the cases considered here the linear force-free field does not produce the break up of the filament nor the production of barbs as a result of dominant polarity elements.

The ''Kinetic Stabilizer'': A Simpler Tandem Mirror Confinement?

International Nuclear Information System (INIS)

Post, R.F.

2000-01-01

In the search for better approaches to magnetic fusion it is important to keep in mind the lessons learned in the 50 years that fusion plasma confinement has been studied. One of the lessons learned is that ''closed'' and ''open'' fusion devices differ fundamentally with respect to an important property of their confinement, as follows: Without known exception closed systems such as the tokamak, the stellarator, or the reversed-field pinch, have been found to have their confinement times limited by non-classical, i.e., turbulence-related, processes, leading to the requirement that such systems must be scaled-up in dimensions to sizes much larger than would be the case in the absence of turbulence. By contrast, from the earliest days of fusion research, it has been demonstrated that open magnetic systems of the mirror variety can achieve confinement times close to that associated with classical, i.e., collisional, processes. While these good results have been obtained in both axially symmetric fields and in non-axisymmetric fields, the clearest cases have been those in which the confining fields are solenoidal and axially symmetric. These observations, i.e., of confinement not enhanced by turbulence, can be traced theoretically to such factors as the absence of parallel currents in the plasma, and to the constraints on particle drifts imposed by the adiabatic invariants governing particle confinement in axisymmetric open systems. In the past the MHD instability of axially symmetric open systems has been seen as a barrier to their use. However, theory predicts MHD-stable confinement is achievable if sufficient plasma is present in the ''good curvature'' regions outside the mirrors. This theory has been confirmed by experiments on the Gas Dynamic Trap mirror-based experiment at Novosibirsk, In this paper a new way of exploiting this stabilizing principle, involving creating a localized ''stabilizer plasma'' outside a mirror, will be discussed. To create this plasma

A comparison of least squares linear regression and measurement error modeling of warm/cold multipole correlation in SSC prototype dipole magnets

International Nuclear Information System (INIS)

Pollock, D.; Kim, K.; Gunst, R.; Schucany, W.

1993-05-01

Linear estimation of cold magnetic field quality based on warm multipole measurements is being considered as a quality control method for SSC production magnet acceptance. To investigate prediction uncertainties associated with such an approach, axial-scan (Z-scan) magnetic measurements from SSC Prototype Collider Dipole Magnets (CDM's) have been studied. This paper presents a preliminary evaluation of the explanatory ability of warm measurement multipole variation on the prediction of cold magnet multipoles. Two linear estimation methods are presented: least-squares regression, which uses the assumption of fixed independent variable (xi) observations, and the measurement error model, which includes measurement error in the xi's. The influence of warm multipole measurement errors on predicted cold magnet multipole averages is considered. MSD QA is studying warm/cold correlation to answer several magnet quality control questions. How well do warm measurements predict cold (2kA) multipoles? Does sampling error significantly influence estimates of the linear coefficients (slope, intercept and residual standard error)? Is estimation error for the predicted cold magnet average small compared to typical variation along the Z-Axis? What fraction of the multipole RMS tolerance is accounted for by individual magnet prediction uncertainty?

Linked tandem mirror configuration as a possible steady state high β plasma container

International Nuclear Information System (INIS)

Ikuta, Kazunari.

1982-04-01

A possibility of achieving steady state high β plasma confinement in toroidal geometry is considered in detail by closing off the ends of tandem mirrors entirely by flux bridges, where β is the ratio of plasma pressure to the magnetic pressure. The key problem of this approach seems to be the magnetic design of magneto-hydrodynamically stabilized, preferentially leaky bridges. (author)

Design and analysis of linear fault-tolerant permanent-magnet vernier machines.

Science.gov (United States)

Xu, Liang; Ji, Jinghua; Liu, Guohai; Du, Yi; Liu, Hu

2014-01-01

This paper proposes a new linear fault-tolerant permanent-magnet (PM) vernier (LFTPMV) machine, which can offer high thrust by using the magnetic gear effect. Both PMs and windings of the proposed machine are on short mover, while the long stator is only manufactured from iron. Hence, the proposed machine is very suitable for long stroke system applications. The key of this machine is that the magnetizer splits the two movers with modular and complementary structures. Hence, the proposed machine offers improved symmetrical and sinusoidal back electromotive force waveform and reduced detent force. Furthermore, owing to the complementary structure, the proposed machine possesses favorable fault-tolerant capability, namely, independent phases. In particular, differing from the existing fault-tolerant machines, the proposed machine offers fault tolerance without sacrificing thrust density. This is because neither fault-tolerant teeth nor the flux-barriers are adopted. The electromagnetic characteristics of the proposed machine are analyzed using the time-stepping finite-element method, which verifies the effectiveness of the theoretical analysis.

Magnetometry of buried layers—Linear magnetic dichroism and spin detection in angular resolved hard X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Gloskovskii, Andrei; Stryganyuk, Gregory; Fecher, Gerhard H.; Felser, Claudia; Thiess, Sebastian; Schulz-Ritter, Heiko; Drube, Wolfgang; Berner, Götz; Sing, Michael; Claessen, Ralph; Yamamoto, Masafumi

2012-01-01

Highlights: ► Newly commissioned HAXPES instrument at P09 beamline of the PETRA III ring at DESY. ► We report HAXPES studies on buried magnetic nanolayers in a multi-layer sample. ► Linear magnetic dichroism of photoelectrons from buried CoFe–Ir 78 Mn 22 layers. ► Spin-resolved HAXPES measurements on buried magnetic multilayers using Mott detector. - Abstract: The electronic properties of buried magnetic nano-layers were studied using the linear magnetic dichroism in the angular distribution of photoemitted Fe, Co, and Mn 2p electrons from a CoFe–Ir 78 Mn 22 multi-layered sample. The buried layers were probed using hard X-ray photoelectron spectroscopy, HAXPES, at the undulator beamline P09 of the 3rd generation storage ring PETRA III. The results demonstrate that this magnetometry technique can be used as a sensitive element specific probe for magnetic properties suitable for application to buried ferromagnetic and antiferromagnetic magnetic materials and multilayered spintronics devices. Using the same instrument, spin-resolved Fe 2p HAXPES spectra were obtained from the buried layer with good signal quality.

Observing complex action sequences: The role of the fronto-parietal mirror neuron system.

Science.gov (United States)

Molnar-Szakacs, Istvan; Kaplan, Jonas; Greenfield, Patricia M; Iacoboni, Marco

2006-11-15

A fronto-parietal mirror neuron network in the human brain supports the ability to represent and understand observed actions allowing us to successfully interact with others and our environment. Using functional magnetic resonance imaging (fMRI), we wanted to investigate the response of this network in adults during observation of hierarchically organized action sequences of varying complexity that emerge at different developmental stages. We hypothesized that fronto-parietal systems may play a role in coding the hierarchical structure of object-directed actions. The observation of all action sequences recruited a common bilateral network including the fronto-parietal mirror neuron system and occipito-temporal visual motion areas. Activity in mirror neuron areas varied according to the motoric complexity of the observed actions, but not according to the developmental sequence of action structures, possibly due to the fact that our subjects were all adults. These results suggest that the mirror neuron system provides a fairly accurate simulation process of observed actions, mimicking internally the level of motoric complexity. We also discuss the results in terms of the links between mirror neurons, language development and evolution.

Neoclassical resonant-plateau transport in the noncircular equipotential surface of a tandem mirror

International Nuclear Information System (INIS)

Katanuma, I.; Kiwamoto, Y.; Ishii, K.; Yatsu, K.; Miyoshi, S.

1988-07-01

Neoclassical resonant-plateau transport in a minimum-B anchored tandem mirror is calculated in an experimentally observed case that a magnetic flux tube of an equipotential contours is not circular at the central cell. (author)

Magnetic holes in the solar wind between 0.3 AU and 17 AU

Directory of Open Access Journals (Sweden)

K. Sperveslage

2000-01-01

Full Text Available Magnetic holes (MHs are depressions of the magnetic field magnitude. Turner et al. (1977 identified the first MHs in the solar wind and determined an occurrence rate of 1.5 MHs/d. Winterhalter et al. (1994 developed an automatic identification criterion to search for MHs in Ulysses data in the solar wind between 1 AU and 5.4 AU. We adopt their criterion to expand the search to the heliocentric distances down to 0.3 AU using data from Helios 1 and 2 and up to 17 AU using data from Voyager 2. We relate our observations to two theoretical approaches which describe the so-called linear MHs in which the magnetic vector varies in magnitude rather than direction. Therefore we focus on such linear MHs with a directional change less than 10º. With our observations of about 850 MHs we present the following results: Approximately 30% of all the identified MHs are linear. The maximum angle between the initial magnetic field vector and any vector inside the MH is 20º in average and shows a weak relation to the depth of the MHs. The angle between the initial magnetic field and the minimum variance direction of those structures is large and very probably close to 90º. The MHs are placed in a high β environment even though the average solar wind shows a smaller β. The widths decrease from about 50 proton inertial length in a region between 0.3 AU and 0.4 AU heliocentric distance to about 15 proton inertial length at distances larger than 10 AU. This quantity is correlated with the β of the MH environments with respect to the heliocentric distance. There is a clear preference for the occurrence of depressions instead of compressions. We discuss these results with regard to the main theories of MHs, the mirror instability and the alternative soliton approach. Although our observational results are more consistent with the soliton theory we favour a combination of both. MHs might be the remnants of initial mirror mode structures which can be described as

Fluxgate magnetometer offset vector determination by the 3D mirror mode method

Science.gov (United States)

Plaschke, F.; Goetz, C.; Volwerk, M.; Richter, I.; Frühauff, D.; Narita, Y.; Glassmeier, K.-H.; Dougherty, M. K.

2017-07-01

Fluxgate magnetometers on-board spacecraft need to be regularly calibrated in flight. In low fields, the most important calibration parameters are the three offset vector components, which represent the magnetometer measurements in vanishing ambient magnetic fields. In case of three-axis stabilized spacecraft, a few methods exist to determine offsets: (I) by analysis of Alfvénic fluctuations present in the pristine interplanetary magnetic field, (II) by rolling the spacecraft around at least two axes, (III) by cross-calibration against measurements from electron drift instruments or absolute magnetometers, and (IV) by taking measurements in regions of well-known magnetic fields, e.g. cometary diamagnetic cavities. In this paper, we introduce a fifth option, the 3-dimensional (3D) mirror mode method, by which 3D offset vectors can be determined using magnetic field measurements of highly compressional waves, e.g. mirror modes in the Earth's magnetosheath. We test the method by applying it to magnetic field data measured by the following: the Time History of Events and Macroscale Interactions during Substorms-C spacecraft in the terrestrial magnetosheath, the Cassini spacecraft in the Jovian magnetosheath and the Rosetta spacecraft in the vicinity of comet 67P/Churyumov-Gerasimenko. The tests reveal that the achievable offset accuracies depend on the ambient magnetic field strength (lower strength meaning higher accuracy), on the length of the underlying data interval (more data meaning higher accuracy) and on the stability of the offset that is to be determined.

Some applications of mirror-generated electric potentials to alternative fusion concepts

International Nuclear Information System (INIS)

Post, R.F.

1990-01-01

Transient electrical potentials can be generated in plasmas by utilizing impulsive mirror-generated forces acting on the plasma electrons together with ion inertia to cause momentary charge imbalance. In the Mirrortron such potentials are generated by applying a rapidly rising (tens of nanoseconds) localized mirror field to the central region of a hot-electron plasma confined between static mirrors. Because of the loss-cone nature of the electron distribution the sudden appearance of the pulsed mirror tends to expel electrons, whereas the ion density remains nearly constant. The quasi-neutrality condition then operates to create an electrical potential the equipotential surfaces of which can be shown theoretically to be congruent with surfaces of constant B. An alternative way of generating transient potentials is to apply a pulse of high-power microwaves to a plasma residing on a magnetic field with a longitudinal gradient. This technique resembles one employed in the Pleiade experiments. At gigawatt power levels, such as those produced by a Free Electron Laser, the production of very high transient potentials is predicted. Fusion-relevant applications of these ideas include heavy-ion drivers for inertial fusion, and the possibility of employing these techniques to enhance the longitudinal confinement of fusion plasmas in multiple-mirror systems. 23 refs., 3 figs

A study on stable levitation of permanent magnet transportation system with coreless linear synchronous motor

Energy Technology Data Exchange (ETDEWEB)

Hiwaki, H [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Watada, M [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Torii, S [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Ebihara, D [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan)

1996-12-31

In the permanent magnet levitation system, it is impossible to stabilize the motion of the vehicle in both levitation and guidance directions only by permanent magnet. Therefore, the authors proposed the combined system of permanent magnet for levitation and coreless linear synchronous motor (coreless LSM). To design the coreless coils for LSM, the method to calculate the spring coefficient between coreless coil and permanent magnet for LSM is shown. By using this method, the spring coefficients of the three coil arrangements are compared and coreless coil is designed. Furthermore, the authors showed the possibility of stabilizing the motion of the levitation system with coreless LSM. (orig.)

The numerical solution of ICRF fields in axisymmetric mirrors

International Nuclear Information System (INIS)

Phillips, M.W.; Todd, A.M.M.

1986-01-01

The numerics of a numerical code called GARFIELD (Grumman Aerospace RF fIELD code) designed to calculate the three-dimensional structure of ICRF fields in axisymmetric mirrors is presented. The code solves the electromagnetic wave equation for the electric field using a cold plasma dispersion relation with a small collision term to simulate absorption. The full wave solution including E.B is computed. The fields are Fourier analyzed in the poloidal direction and solved on a grid in the axial and radial directions. A two-dimensional equilibrium can be used as the source of equilibrium data. This allows us to extend previous studies of ICRF wave propagation and absorption in mirrors to include the effect of axial variation of the magnetic field and density. (orig.)

A novel tubular linear motor equipped with radially anisotropic NdFeB ring magnets

International Nuclear Information System (INIS)

Hor, P.J.

1998-01-01

The paper describes the design synthesis and optimisation of a novel tubular linear motor employing radially magnetised anisotropic ring magnets. Design issues, related to optimising the dimensions for maximum acceleration capability, minimum cogging force and low harmonic distortion in the emf waveform, are discussed. The influence of inhomogeneities in the magnets on the performance of a prototype motor is discussed, and its dynamic performance is validated experimentally against a typical target specification for automated high-speed manufacturing applications. (orig.)

Nb3Sn accelerator magnet technology scale up using cos-theta dipole coils

Energy Technology Data Exchange (ETDEWEB)

Nobrega, F.; Andreev, N.; Ambrosio, G.; Barzi, E.; Bossert, R.; Carcagno, R.; Chlachidze, G.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; /Fermilab

2007-06-01

Fermilab is working on the development of Nb{sub 3}Sn accelerator magnets using shell-type dipole coils and the wind-and-react method. As a part of the first phase of technology development, Fermilab built and tested six 1 m long dipole model magnets and several dipole mirror configurations. The last three dipoles and two mirrors reached their design fields of 10-11 T. The technology scale up phase has started by building 2 m and 4 m dipole coils and testing them in a mirror configuration in which one of the two coils is replaced by a half-cylinder made of low carbon steel. This approach allows for shorter fabrication times and extensive instrumentation preserving almost the same level of magnetic field and Lorentz forces in the coils as in a complete dipole model magnet. This paper presents details on the 2 m (HFDM07) and 4 m long (HFDM08) Nb{sub 3}Sn dipole mirror magnet design and fabrication technology, as well as the magnet test results which are compared with 1 m long models.

Nb3Sn accelerator magnet technology scale up using cos-theta dipole coils

International Nuclear Information System (INIS)

Nobrega, F.; Andreev, N.; Ambrosio, G.; Barzi, E.; Bossert, R.; Carcagno, R.; Chlachidze, G.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Fermilab

2007-01-01

Fermilab is working on the development of Nb 3 Sn accelerator magnets using shell-type dipole coils and the wind-and-react method. As a part of the first phase of technology development, Fermilab built and tested six 1 m long dipole model magnets and several dipole mirror configurations. The last three dipoles and two mirrors reached their design fields of 10-11 T. The technology scale up phase has started by building 2 m and 4 m dipole coils and testing them in a mirror configuration in which one of the two coils is replaced by a half-cylinder made of low carbon steel. This approach allows for shorter fabrication times and extensive instrumentation preserving almost the same level of magnetic field and Lorentz forces in the coils as in a complete dipole model magnet. This paper presents details on the 2 m (HFDM07) and 4 m long (HFDM08) Nb 3 Sn dipole mirror magnet design and fabrication technology, as well as the magnet test results which are compared with 1 m long models

Interim report on the tandem mirror hybrid design study

International Nuclear Information System (INIS)

Moir, R.W.

1979-01-01

The initial phase of a 2-year design study of a tandem mirror fusion reactor is presented. The following chapters are included: (1) mechanical design of the plant; (2) plasma physics; (3) blanket design; (4) magnet design; (5) injector design; (6) direct convertor design; (7) balance of plant design; (8) fission burner reactor; (9) environment and safety; and (10) economic analysis

Design optimization of a linear permanent magnet synchronous motor for extra low force pulsations

International Nuclear Information System (INIS)

Isfahani, Aarsh Hassanpour; Vaez-Zadeh, Sadegh

2007-01-01

Air cored linear permanent magnet synchronous motors have essentially low force pulsations due to the lack of the primary iron core and teeth. However, a motor design with much lower force pulsations is required for many precise positioning systems, as in fabrication of microelectronic chips. This paper presents the design optimization of an air cored linear permanent magnet synchronous motor with extra low force pulsations for such applications. In order to achieve the goal, an analytical layer model of the machine is developed. A very effective objective function regarding force pulsations is then proposed; while the selected motor dimensions are regarded as the design variables. A genetic algorithm is used to find the optimal motor dimensions. This results in a substantial ninety percent reduction in the force pulsations. The design optimization is verified by a finite element method

Use of coaxial plasma guns to start up field-reversed-mirror reactors

International Nuclear Information System (INIS)

Smith, A.C. Jr.; Carlson, G.A.; Eddleman, J.L.; Hartman, C.W.; Neef, W.S. Jr.

1980-01-01

Application of a magnetized coaxial plasma gun for start-up of a field-reversed-mirror reactor is considered. The design is based on preliminary scaling laws and is compared to the design of the start-up gun used in the Beta II experiment

Mirror and (absence of) counter-mirror responses to action sounds measured with TMS.

Science.gov (United States)

Ticini, Luca F; Schütz-Bosbach, Simone; Waszak, Florian

2017-11-01

To what extent is the mirror neuron mechanism malleable to experience? The answer to this question can help characterising its ontogeny and its role in social cognition. Some suggest that it develops through sensorimotor associations congruent with our own actions. Others argue for its extreme volatility that will encode any sensorimotor association in the environment. Here, we added to this debate by exploring the effects of short goal-directed 'mirror' and 'counter-mirror' trainings (a 'mirror' training is defined as the first type of training encountered by the participants) on human auditory mirror motor-evoked potentials (MEPs). We recorded MEPs in response to two tones void of previous motor meaning, before and after mirror and counter-mirror trainings in which participants generated two tones of different pitch by performing free-choice button presses. The results showed that mirror MEPs, once established, were protected against an equivalent counter-mirror experience: they became manifest very rapidly and the same number of training trials that lead to the initial association did not suffice to reverse the MEP pattern. This steadiness of the association argues that, by serving direct-matching purposes, the mirror mechanism is a good solution for social cognition. © The Author (2017). Published by Oxford University Press.

Magnetic spectral signatures in the Earth's magnetosheath and plasma depletion layer

Science.gov (United States)

Anderson, Brian J.; Fuselier, Stephen A.; Gary, S. Peter; Denton, Richard E.

1994-01-01

Correlations between plasma properties and magnetic fluctuations in the sub-solar magnetosheath downstream of a quasi-perpendicular shock have been found and indicate that mirror and ion cyclotronlike fluctuations correlate with the magnetosheath proper and plasma depletion layer, respectively (Anderson and Fueselier, 1993). We explore the entire range of magnetic spectral signatures observed from the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE)spacecraft in the magnetosheath downstream of a quasi-perpendicular shock. The magnetic spectral signatures typically progress from predominantly compressional fluctuations,delta B(sub parallel)/delta B perpendicular to approximately 3, with F/F (sub p) less than 0.2 (F and F (sub p) are the wave frequency and proton gyrofrequency, respectively) to predominantly transverse fluctuations, delta B(sub parallel)/delta B perpendicular to approximately 0.3, extending up to F(sub p). The compressional fluctuations are characterized by anticorrelation between the field magnitude and electron density, n(sub e), and by a small compressibility, C(sub e) identically equal to (delta n(sub e)/n(sub e)) (exp 2) (B/delta B(sub parallel)) (exp 2) approximately 0.13, indicative of mirror waves. The spectral characteristics of the transverse fluctuations are in agreement with predictions of linear Vlasov theory for the H(+) and He(2+) cyclotron modes. The power spectra and local plasma parameters are found to vary in concert: mirror waves occur for beta(s ub parallel p) (beta (sub parallel p) identically = 2 mu(sub zero) n(sub p) kT (sub parallel p) / B(exp 2) approximately = 2, A(sub p) indentically = T(sub perpendicular to p)/T(sub parallel p) - 1 approximately = 0.4, whereas cyclotron waves occur for beta (sub parallel p) approximately = 0.2 and A(sub p) approximately = 2. The transition from mirror to cyclotron modes is predicted by linear theory. The spectral characteristics overlap for

Generation of intense, high-energy ion pulses by magnetic compression of ion rings

International Nuclear Information System (INIS)

Kapetanakos, C.A.

1981-01-01

A system based on the magnetic compression of ion rings, for generating intense (High-current), high-energy ion pulses that are guided to a target without a metallic wall or an applied external magnetic field includes a vacuum chamber; an inverse reflex tetrode for producing a hollow ion beam within the chamber; magnetic coils for producing a magnetic field, bo, along the axis of the chamber; a disc that sharpens a magnetic cusp for providing a rotational velocity to the beam and causing the beam to rotate; first and second gate coils for producing fast-rising magnetic field gates, the gates being spaced apart, each gate modifying a corresponding magnetic mirror peak (Near and far peaks) for trapping or extracting the ions from the magnetic mirror, the ions forming a ring or layer having rotational energy; a metal liner for generating by magnetic flux compression a high, time-varying magnetic field, the time-varying magnetic field progressively increasing the kinetic energy of the ions, the magnetic field from the second gate coil decreasing the far mirror peak at the end of the compression for extracting the trapped rotating ions from the confining mirror; and a disc that sharpens a magnetic half-cusp for increasing the translational velocity of the ion beam. The system utilizes the self-magnetic field of the rotating, propagating ion beam to prevent the beam from expanding radially upon extraction

Simple atom trap in a conical hollow mirror: Numerical analysis

International Nuclear Information System (INIS)

Kim, J. A.; Lee, K. I.; Nha, H.; Noh, H. R.; Yoo, S. H.; Jhe, W

1996-01-01

We analyze the trap dynamic in a conical hollow (axicon) mirror system. Atom's trajectory is ring shaped if we move the coil (magnetic field) axis off the mirror axis and if we overlap these two axes trap cloud is ball shaped and it is consistent with experiment. We also make a simple comparison between 6-beam MOT and axicon MOT in the ball shaped case, and it shows that at low velocity limit the axicon MOT and typical 6-beam MOT have nearly same trap properties. The axicon trap may be useful as precooled atom source for many other atomic physics experiments such as cold atomic beam, atom funnel, and atom waveguide.

Characterization of high flux magnetized helium plasma in SCU-PSI linear device

Science.gov (United States)

Xiaochun, MA; Xiaogang, CAO; Lei, HAN; Zhiyan, ZHANG; Jianjun, WEI; Fujun, GOU

2018-02-01

A high-flux linear plasma device in Sichuan University plasma-surface interaction (SCU-PSI) based on a cascaded arc source has been established to simulate the interactions between helium and hydrogen plasma with the plasma-facing components in fusion reactors. In this paper, the helium plasma has been characterized by a double-pin Langmuir probe. The results show that the stable helium plasma beam with a diameter of 26 mm was constrained very well at a magnetic field strength of 0.3 T. The core density and ion flux of helium plasma have a strong dependence on the applied current, magnetic field strength and gas flow rate. It could reach an electron density of 1.2 × 1019 m-3 and helium ion flux of 3.2 × 1022 m-2 s-1, with a gas flow rate of 4 standard liter per minute, magnetic field strength of 0.2 T and input power of 11 kW. With the addition of -80 V applied to the target to increase the helium ion energy and the exposure time of 2 h, the flat top temperature reached about 530 °C. The different sizes of nanostructured fuzz on irradiated tungsten and molybdenum samples surfaces under the bombardment of helium ions were observed by scanning electron microscopy. These results measured in the SCU-PSI linear device provide a reference for International Thermonuclear Experimental Reactor related PSI research.

A universal mirror wave-mode threshold condition for non-thermal space plasma environments

Directory of Open Access Journals (Sweden)

M. P. Leubner

2002-01-01

Full Text Available Magnetic fluctuations are recognized in a large variety of space plasmas by increasingly high resolution, in situ observations as mirror wave mode structures. A typical requirement for the excitation of mirror modes is a dominant perpendicular pressure in a high-beta plasma environment. Contrary, we demonstrate from a realistic kinetic analysis how details of the velocity space distributions are of considerable significance for the instability threshold. Introducing the most common characteristics of observed ion and electron distributions by a mixed suprathermal-loss-cone, we derive a universal mirror instability criterion from an energy principle for collisionless plasmas. As a result, the transition from two temperature Maxwellians to realistic non-thermal features provides a strong source for the generation of mirror wave mode activity, reducing drastically the instability threshold. In particular, a number of space-related examples illuminate how the specific structure of the velocity space distribution dominates as a regulating excitation mechanism over the effects related to changes in the plasma parameters.

Five degree-of-freedom control of an ultra-precision magnetically-suspended linear bearing. Ph.D. Thesis - MIT

Science.gov (United States)

Trumper, David L.; Slocum, A. H.

1991-01-01

The authors constructed a high precision linear bearing. A 10.7 kg platen measuring 125 mm by 125 mm by 350 mm is suspended and controlled in five degrees of freedom by seven electromagnets. The position of the platen is measured by five capacitive probes which have nanometer resolution. The suspension acts as a linear bearing, allowing linear travel of 50 mm in the sixth degree of freedom. In the laboratory, this bearing system has demonstrated position stability of 5 nm peak-to-peak. This is believed to be the highest position stability yet demonstrated in a magnetic suspension system. Performance at this level confirms that magnetic suspensions can address motion control requirements at the nanometer level. The experimental effort associated with this linear bearing system is described. Major topics are the development of models for the suspension, implementation of control algorithms, and measurement of the actual bearing performance. Suggestions for the future improvement of the bearing system are given.

Electrostatic systems used for the multipassage magnetic mass spectrometers

Energy Technology Data Exchange (ETDEWEB)

Berger, C; Baril, M

1987-08-15

Improvement in the power of resolution is desirable in the multiplication of passages in magnetic fields; our guiding principle is to carry out the operation using a single magnetic prism. In the multipassage process the ions must first turn back after leaving the prism. This turnback is obtained by an electrostatic mirror. We obtain a large enough number of passages by placing two mirrors and two systems with time-varying roles at right angles. These systems are referred to as lens-mirror 1. When they act as mirrors, they enable the particles to circulate in a closed circuit; when they act as lenses, they enable the particles to enter the circuit or leave it. The coupling of two multipassage spectrometers is momentarily possible thanks to lens-mirror 2. The function change results from a change in electrode potential. The requirements for these electrostatic systems and their construction are studied.

Stable operation of an effectively axisymmetric neutral beam driven tandem mirror

International Nuclear Information System (INIS)

Molvik, A.W.; Barter, J.D.; Buchenauer, D.A.; Casper, T.A.; Correll, D.L.; Dimonte, G.; Falabella, S.; Foote, J.H.; Pincosy, P.A.

1990-01-01

A quiescent plasma is sustained for 80 energy confinement times by only gas fuelling and neutral beam heating in an axisymmetric region of the Tandem Mirror Experiment Upgrade (TMX-U). This plasma should be unstable because of the bad magnetic curvature and the absence of ion cyclotron heating which previously provided ponderomotive stabilization to sustain plasmas in bad-curvature regions of other axisymmetric mirror experiments. The TMX-U data are consistent with stabilization by a symbiosis between two mechanisms - line tying, which reduces the growth rate, and finite Larmor radius edge stabilization, which can result in quiescent operation. (author). 42 refs, 8 figs, 1 tab

The mirror neuron system.

Science.gov (United States)

Cattaneo, Luigi; Rizzolatti, Giacomo

2009-05-01

Mirror neurons are a class of neurons, originally discovered in the premotor cortex of monkeys, that discharge both when individuals perform a given motor act and when they observe others perform that same motor act. Ample evidence demonstrates the existence of a cortical network with the properties of mirror neurons (mirror system) in humans. The human mirror system is involved in understanding others' actions and their intentions behind them, and it underlies mechanisms of observational learning. Herein, we will discuss the clinical implications of the mirror system.

Study on a high thrust force bi-double-sided permanent magnet linear synchronous motor

Directory of Open Access Journals (Sweden)

Liang Tong

2016-03-01

Full Text Available A high thrust force bi-double-sided permanent magnet linear synchronous motor used in gantry-type five-axis machining center is designed and its performance was tested in this article. This motor is the subproject of Chinese National Science and Technology Major Project named as “development of domestic large thrust linear motor used in high-speed gantry-type five-axis machining center project” jointly participated by enterprises and universities. According to the requirement of the application environment and motor performance parameters, the linear motor’s basic dimensions, form of windings, and magnet arrangement are preliminarily specified through theoretical analysis and calculation. To verify the correctness of the result of the calculation, the finite element model of the motor is established. The static and dynamic characteristics of the motor are studied and analyzed through the finite element method, and the initial scheme is revised. The prototype of the motor is manufactured based on the final revised structure parameters, and the performance of the motor is fully tested using the evaluation platform for direct-drive motor component. Experimental test results meet the design requirements and show the effectiveness of design method and process.

Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure

Energy Technology Data Exchange (ETDEWEB)

Zlobin, Alexander [Fermilab; Andreev, Nicolai [Fermilab; Barzi, Emanuela [Fermilab; Chlachidze, Guram [Fermilab; Kashikhin, Vadim [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Turrioni, Daniele [Fermilab; Karppinen, Mikko [CERN; Smekens, David [CERN

2014-07-01

FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC. To optimize coil design parameters and fabrication process and study coil performance, a series of 1 m long dipole coils is being fabricated. One of the short coils has been tested using a dipole mirror structure. This paper describes the dipole mirror magnetic and mechanical designs, and reports coil parameters and test results.

The Properties of Lion Roars and Electron Dynamics in Mirror Mode Waves Observed by the Magnetospheric MultiScale Mission

Science.gov (United States)

Breuillard, H.; Le Contel, O.; Chust, T.; Berthomier, M.; Retino, A.; Turner, D. L.; Nakamura, R.; Baumjohann, W.; Cozzani, G.; Catapano, F.; Alexandrova, A.; Mirioni, L.; Graham, D. B.; Argall, M. R.; Fischer, D.; Wilder, F. D.; Gershman, D. J.; Varsani, A.; Lindqvist, P.-A.; Khotyaintsev, Yu. V.; Marklund, G.; Ergun, R. E.; Goodrich, K. A.; Ahmadi, N.; Burch, J. L.; Torbert, R. B.; Needell, G.; Chutter, M.; Rau, D.; Dors, I.; Russell, C. T.; Magnes, W.; Strangeway, R. J.; Bromund, K. R.; Wei, H.; Plaschke, F.; Anderson, B. J.; Le, G.; Moore, T. E.; Giles, B. L.; Paterson, W. R.; Pollock, C. J.; Dorelli, J. C.; Avanov, L. A.; Saito, Y.; Lavraud, B.; Fuselier, S. A.; Mauk, B. H.; Cohen, I. J.; Fennell, J. F.

2018-01-01

Mirror mode waves are ubiquitous in the Earth's magnetosheath, in particular behind the quasi-perpendicular shock. Embedded in these nonlinear structures, intense lion roars are often observed. Lion roars are characterized by whistler wave packets at a frequency ˜100 Hz, which are thought to be generated in the magnetic field minima. In this study, we make use of the high time resolution instruments on board the Magnetospheric MultiScale mission to investigate these waves and the associated electron dynamics in the quasi-perpendicular magnetosheath on 22 January 2016. We show that despite a core electron parallel anisotropy, lion roars can be generated locally in the range 0.05-0.2fce by the perpendicular anisotropy of electrons in a particular energy range. We also show that intense lion roars can be observed up to higher frequencies due to the sharp nonlinear peaks of the signal, which appear as sharp spikes in the dynamic spectra. As a result, a high sampling rate is needed to estimate correctly their amplitude, and the latter might have been underestimated in previous studies using lower time resolution instruments. We also present for the first-time 3-D high time resolution electron velocity distribution functions in mirror modes. We demonstrate that the dynamics of electrons trapped in the mirror mode structures are consistent with the Kivelson and Southwood (1996) model. However, these electrons can also interact with the embedded lion roars: first signatures of electron quasi-linear pitch angle diffusion and possible signatures of nonlinear interaction with high-amplitude wave packets are presented. These processes can lead to electron untrapping from mirror modes.

Linear field demagnetisation of artificial magnetic square ice

Directory of Open Access Journals (Sweden)

Jason Phillip Morgan

2013-12-01

Full Text Available We have studied experimentally the states formed in artificial square ice nanomagnet systems following demagnetisation in a rotating in-plane applied magnetic field that reduces to zero in a manner that is linear in time. The final states are found to be controlled via the system's lattice constant, which determines the strength of the magnetostatic interactions between the elements, as well as the field ramping rate. We understand these effects as a requirement that the system undergoes a sufficiently large number of active rotations within the critical field window in which elements may be reversed, such that the interactions are allowed to locally exert their influence if the ground state is to be approached. On the other hand, if quenched disorder is too strong when compared to the interaction strength, any close approach to the ground state is impossible. These results show that it is not necessary for there to be any ac component to the field amplitude that is applied to the system during demagnetisation, which is the method almost exclusively employed in field protocols reported to date. Furthermore, by optimising the parameters of our linear demagnetisation protocol, the largest field-generated ground state domains yet reported are found.

Magnetic orientation of paraffin in a magnetic levitation furnace

Science.gov (United States)

Takahashi, K.; Umeki, C.; Mogi, I.; Koyama, K.; Awaji, S.; Motokawa, M.; Watanabe, K.

2004-04-01

Containerless melting of paraffin under a magnetic levitation condition has been performed by using a cryogen-free hybrid magnet and two kinds of laser furnaces. One is local irradiation of CO 2 laser light at the top of the sample. The other is homogeneous irradiation of YAG laser light with a concave ring mirror. In the latter case, reduction of the Marangoni convection on the surface of the sample and the magnetic orientation of paraffin molecules were observed. The magnetic anisotropy of the spherical sample was confirmed by the measurement of magnetization and X-ray diffraction.

Magnetic orientation of paraffin in a magnetic levitation furnace

Energy Technology Data Exchange (ETDEWEB)

Takahashi, K.; Umeki, C.; Mogi, I.; Koyama, K.; Awaji, S.; Motokawa, M.; Watanabe, K

2004-04-30

Containerless melting of paraffin under a magnetic levitation condition has been performed by using a cryogen-free hybrid magnet and two kinds of laser furnaces. One is local irradiation of CO{sub 2} laser light at the top of the sample. The other is homogeneous irradiation of YAG laser light with a concave ring mirror. In the latter case, reduction of the Marangoni convection on the surface of the sample and the magnetic orientation of paraffin molecules were observed. The magnetic anisotropy of the spherical sample was confirmed by the measurement of magnetization and X-ray diffraction.

Magnetic orientation of paraffin in a magnetic levitation furnace

International Nuclear Information System (INIS)

Takahashi, K.; Umeki, C.; Mogi, I.; Koyama, K.; Awaji, S.; Motokawa, M.; Watanabe, K.

2004-01-01

Containerless melting of paraffin under a magnetic levitation condition has been performed by using a cryogen-free hybrid magnet and two kinds of laser furnaces. One is local irradiation of CO 2 laser light at the top of the sample. The other is homogeneous irradiation of YAG laser light with a concave ring mirror. In the latter case, reduction of the Marangoni convection on the surface of the sample and the magnetic orientation of paraffin molecules were observed. The magnetic anisotropy of the spherical sample was confirmed by the measurement of magnetization and X-ray diffraction

MSFC Test Results for Selected Mirrors: Brush-Wellman/Goodrich 0.5 meter Joined-Beryllium Mirror; IABG 0.5 meter C/SiC Mirror; Xinetics 0.5 meter SiC Mirror; and Kodak 0.23 meter SiO2 Mirror

Science.gov (United States)

Hadaway, James; Blackwell, Lisa; Matthews, Gary; Eng, Ron; Stahl, Phil; Hraba, John; Thornton, Gary

2002-01-01

The results of cryo tests performed at the XRCF on the above mirrors will be presented. Each mirror was tested from room-temperature to around 30 K. The first three were tested together on a 3-mirror stand in the large chamber using the PhaseCam interferometer, while the Kodak mirror was tested in the small chamber using the EPI interferometer.

Three-dimensional linear peeling-ballooning theory in magnetic fusion devices

Energy Technology Data Exchange (ETDEWEB)

Weyens, T., E-mail: tweyens@fis.uc3m.es; Sánchez, R.; García, L. [Departamento de Física, Universidad Carlos III de Madrid, Madrid 28911 (Spain); Loarte, A.; Huijsmans, G. [ITER Organization, Route de Vinon sur Verdon, 13067 Saint Paul Lez Durance (France)

2014-04-15

Ideal magnetohydrodynamics theory is extended to fully 3D magnetic configurations to investigate the linear stability of intermediate to high n peeling-ballooning modes, with n the toroidal mode number. These are thought to be important for the behavior of edge localized modes and for the limit of the size of the pedestal that governs the high confinement H-mode. The end point of the derivation is a set of coupled second order ordinary differential equations with appropriate boundary conditions that minimize the perturbed energy and that can be solved to find the growth rate of the perturbations. This theory allows of the evaluation of 3D effects on edge plasma stability in tokamaks such as those associated with the toroidal ripple due to the finite number of toroidal field coils, the application of external 3D fields for elm control, local modification of the magnetic field in the vicinity of ferromagnetic components such as the test blanket modules in ITER, etc.

Plasma heating and hot ion sustaining in mirror based hybrids

International Nuclear Information System (INIS)

Moiseenko, V. E.; Ågren, O.

2012-01-01

Possibilities of plasma heating and sloshing ion sustaining in mirror based hybrids are briefly reviewed. Sloshing ions, i.e. energetic ions with a velocity distribution concentrated to a certain pitch-angle, play an important role in plasma confinement and generation of fusion neutrons in mirror machines. Neutral beam injection (NBI) is first discussed as a method to generate sloshing ions. Numerical results of NBI modeling for a stellarator-mirror hybrid are analyzed. The sloshing ions could alternatively be sustained by RF heating. Fast wave heating schemes, i.e. magnetic beach, minority and second harmonic heating, are addressed and their similarities and differences are described. Characteristic features of wave propagation in mirror hybrid devices including both fundamental harmonic minority and second harmonic heating are examined. Minority heating is efficient for a wide range of minority concentration and plasma densities; it allows one to place the antenna aside from the hot ion location. A simple-design strap antenna suitable for this has good performance. However, this scenario is appropriate only for light minority ions. The second harmonic heating can be applied for the heavy ion component. Arrangements are similar for minority and second harmonic heating. The efficiency of second harmonic heating is influenced by a weaker wave damping than for minority heating. Numerical calculations show that in a hybrid reactor scaled mirror machine the deuterium sloshing ions could be heated within the minority heating scheme, while the tritium ions could be sustained by second harmonic heating.

Magnet pole shape design for reduction of thrust ripple of slotless permanent magnet linear synchronous motor with arc-shaped magnets considering end-effect based on analytical method

Directory of Open Access Journals (Sweden)

Kyung-Hun Shin

2017-05-01

Full Text Available The shape of the magnet is essential to the performance of a slotless permanent magnet linear synchronous machine (PMLSM because it is directly related to desirable machine performance. This paper presents a reduction in the thrust ripple of a PMLSM through the use of arc-shaped magnets based on electromagnetic field theory. The magnetic field solutions were obtained by considering end effect using a magnetic vector potential and two-dimensional Cartesian coordinate system. The analytical solution of each subdomain (PM, air-gap, coil, and end region is derived, and the field solution is obtained by applying the boundary and interface conditions between the subdomains. In particular, an analytical method was derived for the instantaneous thrust and thrust ripple reduction of a PMLSM with arc-shaped magnets. In order to demonstrate the validity of the analytical results, the back electromotive force results of a finite element analysis and experiment on the manufactured prototype model were compared. The optimal point for thrust ripple minimization is suggested.

Selection of the optimum magnet design for the International Linear Collider positron source helical undulator

Directory of Open Access Journals (Sweden)

D. J. Scott

2007-03-01

Full Text Available A comparison of possible undulator designs for the International Linear Collider positron source has resulted in a superconducting bifilar wire design being selected. After a comprehensive paper study and fabrication of the two preeminent designs, the superconducting undulator was chosen instead of the permanent magnet alternative. This was because of its superior performance in terms of magnetic field strength and quality, operational flexibility, risk of radiation damage, ease in achieving the required vacuum, and cost. The superconducting undulator design will now be developed into a complete system design for the full 200 m long magnet that is required.

Engineering problems of tandem-mirror reactors

International Nuclear Information System (INIS)

Moir, R.W.; Barr, W.L.; Boghosian, B.M.

1981-01-01

We have completed a comparative evaluation of several end plug configurations for tandem mirror fusion reactors with thermal barriers. The axi-cell configuration has been selected for further study and will be the basis for a detailed conceptual design study to be carried out over the next two years. The axi-cell end plug has a simple mirror cell produced by two circular coils followed by a transition coil and a yin-yang pair, which provides for MHD stability. This paper discusses some of the many engineering problems facing the designer. We estimated the direct cost to be 2$/W/sub e/. Assuming total (direct and indirect) costs to be twice this number, we need to reduce total costs by factors between 1.7 and 2.3 to compete with future LWRs levelized cost of electricity. These reductions may be possible by designing magnets producing over 20T made possible by use of combinations of superconducting and normal conducting coils as well as improvements in performance and cost of neutral beam and microwave power systems. Scientific and technological understanding and innovation are needed in the area of thermal barrier pumping - a process by which unwanted particles are removed (pumped) from certain regions of velocity and real space in the end plug. Removal of exhaust fuel ions, fusion ash and impurities by action of a halo plasma and plasma dump in the mirror end region is another challenging engineering problem discussed in this paper

Magnetism of hexagonal close-packed nickel calculated by full-potential linearized augmented plane wave method

International Nuclear Information System (INIS)

Tian, F.; Tian, H.; Whitmore, L.; Ye, L.Y.

2015-01-01

The energy dependent on volume of hexagonal close-packed (hcp) nickel with different magnetism is calculated by full-potential linearized augmented plane wave method. Based on the calculation ferromagnetic state is found to be the most stable state. The magnetic moment of hcp Ni is calculated and compared to those calculated by different pseudo-potential methods. Furthermore, it is also compared to that of face-centered cubic (fcc) one with the reason discussed

Handbook on linear motor application

International Nuclear Information System (INIS)

1988-10-01

This book guides the application for Linear motor. It lists classification and speciality of Linear Motor, terms of linear-induction motor, principle of the Motor, types on one-side linear-induction motor, bilateral linear-induction motor, linear-DC Motor on basic of the motor, linear-DC Motor for moving-coil type, linear-DC motor for permanent-magnet moving type, linear-DC motor for electricity non-utility type, linear-pulse motor for variable motor, linear-pulse motor for permanent magneto type, linear-vibration actuator, linear-vibration actuator for moving-coil type, linear synchronous motor, linear electromagnetic motor, linear electromagnetic solenoid, technical organization and magnetic levitation and linear motor and sensor.

Design of an ellipsoidal mirror for freewave characterization of materials at microwave frequencies

International Nuclear Information System (INIS)

Rojo, M; Muñoz, J; Molina-Cuberos, G J; Margineda, J; García-Collado, Á J

2016-01-01

Free-wave characterization of the electromagnetic properties of materials at microwave frequencies requires that scattering at the edges of the samples and/or holder be minimized. Here, an ellipsoidal mirror is designed and characterized in order to decrease the size of the beam, thereby avoiding the scattering problems, even when relatively small samples are used. In the experimental configuration, both the emitting antenna and sample are located at the mirror focuses. Since both the emitted and reflected (focused) beams are Gaussian in nature, we make use of Gaussian beam theory to carry out the design. The mirror parameters are optimized by numerical simulations (COMSOL Multiphysics ® ) and then experimentally tested. An experimental setup is presented for dielectric, magnetic and chiral measurement in the 4.5–18 GHz band. (paper)

Biological responses of human solid tumor cells to X-ray irradiation within a 1.5-Tesla magnetic field generated by a magnetic resonance imaging–linear accelerator

NARCIS (Netherlands)

Wang, Li; Hoogcarspel, Stan Jelle; Wen, Zhifei; van Vulpen, Marco; Molkentine, David P.; Kok, Jan; Lin, Steven H.; Broekhuizen, Roel; Ang, Kie Kian; Bovenschen, Niels; Raaymakers, Bas W.; Frank, Steven J.

2016-01-01

Devices that combine magnetic resonance imaging with linear accelerators (MRL) represent a novel tool for MR-guided radiotherapy. However, whether magnetic fields (MFs) generated by these devices affect the radiosensitivity of tumors is unknown. We investigated the influence of a 1.5-T MF on cell

ELECTRON TRAPPING IN WIGGLER AND QUADRUPOLE MAGNETS OF CESRTA

International Nuclear Information System (INIS)

Wang, Lanfa

2010-01-01

The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in the wiggler and quadrupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with long lifetime in a quadrupole magnet due to the mirror field trapping mechanism and photoelectrons produced in the wiggler zero field zone have long lifetime due to their complicated trajectory.

Physics-magnetics trade studies for tandem mirror reactors

International Nuclear Information System (INIS)

Campbell, R.B.; Perkins, L.J.; Blackfield, D.T.

1985-01-01

We describe and present results obtained from the optimization package of the Tandem Mirror Reactor Systems Code. We have found it to be very useful in searching through multidimensional parameter space, and have applied it here to study the effect of choke coil field strength and net electric power on cost of electricity (COE) and mass utilization factor (MUF) for MINIMARS type reactors. We have found that a broad optimum occurs at B/sub choke/ = 26 T for both COE and MUF. The COE economy of scale approaches saturation at quite low powers, around 600 MW(e). The saturation is mainly due to longer construction times for large plants, and the associated time related costs. The MUF economy of scale does not saturate, at least for powers up to 2400 MW(e)

Theory of the optimal design of straight-axis minimum-B mirror confinement configurations

International Nuclear Information System (INIS)

Hall, L.S.

1982-01-01

The design of modern straight-axis linked-mirror plasma-confinement configurations involves a balance between many competing requirements. The dipole and quadrupole components of magnetic induction required in one confinement region often do not match onto the fields of an adjacent region without complications that seriously affect particle drifts or confinement stability. Here, the relevant factors are set down together with the techniques for analytical optimization of the design of a general configuration. A general sufficient condition for the stability of an arbitrary guiding-center MHD equilibrium is derived. This condition makes explicit the stabilizing qualities of good normal curvature and diamagnetic axial current. The instability drive depends on two terms: one carries the sign of normal curvature and the other relates to the relative signs of geodeics curvature and geodesic torsion. The theory is applied to low-beta, large-aspect-ratio equilibria for which analytic expressions for the confining magnetic fields are known. Two optimizations are required to specify the arbitrary features of the quadrupole and dipole fields. One optimization is nonlinear and can be performed by the ordinary calculus of variations; the second optimization is linear and subject to the rules of game theory. Appropriate quality factors are obtained, thus giving the designer quantitative measures with which to balance design trade-offs

Preliminary design study of the Tandem Mirror Reactor (TMR)

International Nuclear Information System (INIS)

Moir, R.W.; Barr, W.L.; Carlson, G.A.

1978-01-01

This report describes work done in Fiscal Year 1977 by the Fusion Reactor Studies Group of LLL on the conceptual design of a 1000-MW(e) Tandem Mirror Reactor (TMR). The high Q (defined as the ratio of fusion power to injection power) predicted for the TMR (approximately 5) reduces the recirculating power to a nondominant problem and results in an attractive mirror fusion power plant. The fusion plasma of the TMR is contained in the 100-m-long central cell where the magnetic field strength is a modest 2 T. The blanket for neutron energy recovery and tritium breeding is cylindrical and, along with the solenoidal magnet, is divided into 3-m-long modules to facilitate maintenance. The central cell is fueled (but not heated) by the injection of low-energy neutral beams near its ends. Thus, the central cell is simple and of low technology. The end-cell plasmas must be of high density and high energy in order to plug and heat (via the electrons) the central-cell plasma. The present conceptual design uses 1.2-MeV neutral-beam injection for the end plugs and a cryogenic-aluminum, Yin-Yang magnet that produces an incremental field of about 1 T over a field of 16 T produced by a pair of Nb 3 Sn superconducting solenoids. Important design problems remain in both the neutral-beam injector and in the end-plug magnet. Also remaining are important physics questions such as alpha-beam particle transport and end-plug stability. These questions are discussed at length in the report and suggestions for future work are given

Linear instability and nonlinear motion of rotating plasma

International Nuclear Information System (INIS)

Liu, J.

1985-01-01

Two coupled nonlinear equations describing the flute dynamics of the magnetically confined low-β collisionless rotating plasma are derived. The linear instability and nonlinear dynamics of the rotating column are analyzed theoretically. In the linear stability analysis, a new sufficient condition of stability is obtained. From the exact solution of eigenvalue equation for Gaussian density profile and uniform rotation of the plasma, the stability of the system strongly depends on the direction of plasma rotation, FLR effect and the location of the conducting wall. An analytic expression showing the finite wall effect on different normal modes is obtained and it explains the different behavior of (1,0) normal mode from other modes. The sheared rotation driven instability is investigated by using three model equilibrium profiles, and the analytic expressions of eigenvalues which includes the wall effect are obtained. The analogy between shear rotation driven instability and the instability driven by sheared plane parallel flow in the inviscid fluid is analyzed. Applying the linear analysis to the central cell of tandem mirror system, the trapped particle instability with only passing electronics is analyzed. For uniform rotation and Gaussian density profile, an analytic expression that determines the stability boundary is found. The nonlinear analysis shows that the nonlinear equations have a solitary vortex solution which is very similar to the vortex solution of nonlinear Rossby wave equation

A Superstrong Adjustable Permanent Magnet for the Final Focus Quadrupole in a Linear Collider