WorldWideScience

Sample records for pulse mhd-emp effects

  1. Methodology to assess the effects of magnetohydrodynamic electromagnetic pulse (MHD-EMP) on power systems

    International Nuclear Information System (INIS)

    Legro, J.R.; Abi-Samra, N.C.; Crouse, J.C.; Tesche, F.M.

    1985-01-01

    This paper summarizes a method to evaluate the possible effects of magnetohydrodynamic-electromagnetic pulse (MHD-EMP) on power systems. This method is based on the approach adapted to study the impact of geomagnetic storms on power systems. The paper highlights the similarities and differences between the two phenomena. Also presented are areas of concern which are anticipated from MHD-EMP on the overall system operation. 12 refs., 1 fig

  2. Magnetohydrodynamic Electromagnetic Pulse (MHD-EMP) Interaction with Power Transmission and Distribution Systems

    National Research Council Canada - National Science Library

    Tesche, F. M; Barnes, P. R; Meliopoulos, A. P

    1992-01-01

    .... This environment, known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP , is a very slowly varying electric field induced in the earth's surface, similar to the field induced by a geomagnetic storm...

  3. Nuclear magnetohydrodynamic EMP, solar storms, and substorms

    International Nuclear Information System (INIS)

    Rabinowitz, M.; Meliopoulous, A.P.S.; Glytsis, E.N.

    1992-01-01

    In addition to a fast electromagnetic pulse (EMP), a high altitude nuclear burst produces a relatively slow magnetohydrodynamic EMP (MHD EMP), whose effects are like those from solar storm geomagnetically induced currents (SS-GIC). The MHD EMP electric field E approx-lt 10 - 1 V/m and lasts approx-lt 10 2 sec, whereas for solar storms E approx-gt 10 - 2 V/m and lasts approx-gt 10 3 sec. Although the solar storm electric field is lower than MHD EMP, the solar storm effects are generally greater due to their much longer duration. Substorms produce much smaller effects than SS-GIC, but occur much more frequently. This paper describes the physics of such geomagnetic disturbances and analyzes their effects

  4. Effects of nuclear electromagnetic pulse (EMP) on nuclear power plants

    International Nuclear Information System (INIS)

    Barnes, P.R.; Manweiler, R.W.; Davis, R.R.

    1977-09-01

    The electromagnetic pulse (EMP) from a high-altitude nuclear detonation consists of a transient pulse of high intensity electromagnetic fields. These intense fields induce current and voltage transients in electrical conductors. Although most nuclear power plant cables are not directly exposed to these fields, the attenuated EMP fields that propagate into the plant will couple some EMP energy to these cables. The report predicts the probable effects of the EMP transients that could be induced in critical circuits of safety-related systems. It was found that the most likely consequence of EMP for nuclear plants is an unscheduled shutdown. EMP could prolong the shutdown period by the unnecessary actuation of certain safety systems. In general, EMP could be a nuisance to nuclear power plants, but it is not considered a serious threat to plant safety

  5. Principles and techniques of radiation hardening. Volume 3. Electromagnetic pulse (EMP) and system generated EMP

    International Nuclear Information System (INIS)

    Rudie, N.J.

    1976-01-01

    The three-volume book is intended to serve as a review of the effects of thermonuclear explosion induced radiation (x-rays, gamma rays, and beta particles) and the resulting electromagnetic pulse (EMP). Volume 3 deals with the following topics: selected fundamentals of electromagnetic theory; EMP induced currents on antennas and cables; the EMP response of electronics; EMP hardening; EMP testing; injection currents; internal electromagnetic pulse (IEMP); replacement currents; and system generated electromagnetic pulse (SGEMP) hardening

  6. Studies of Effect Analysis of Electromagnetic Pulses (EMP) in Operating Nuclear Power Plants (NPP)

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Song Hae; Ryu, Ho Sun; Kim, Min Yi; Lee, Eui Jong [KHNP, Daejeon (Korea, Republic of)

    2016-05-15

    The effect analysis of electromagnetic pulses (EMPs) has been studied for the past year by the Central Research Institute of Korea Hydro Nuclear Power Co. (KHNP) in order to better establish safety measures in operating nuclear power plants. What is an electromagnetic pulse (EMP)? As a general term for high-power electromagnetic radiation, it refers to strong electromagnetic pulses that destroy only electronic equipment devices in a short period without loss of life. The effect analysis of EMPs in operating NPPs and their corresponding safety measures in terms of selecting target devices against EMP impact have been examined in this paper. In general, domestic nuclear power plants do apply the design of fail-safe concepts. For example, if key instruments of a system fail because of EMPs, the control rods of a nuclear reactor are dropped automatically in order to maintain safe conditions of the NPP. Reactor cooling presents no problem because the diesel generator will adopt the analog starting circuit least affected by the electromagnetic waves.

  7. Design of a bounded wave EMP (Electromagnetic Pulse) simulator

    Science.gov (United States)

    Sevat, P. A. A.

    1989-06-01

    Electromagnetic Pulse (EMP) simulators are used to simulate the EMP generated by a nuclear weapon and to harden equipment against the effects of EMP. At present, DREO has a 1 m EMP simulator for testing computer terminal size equipment. To develop the R and D capability for testing larger objects, such as a helicopter, a much bigger threat level facility is required. This report concerns the design of a bounded wave EMP simulator suitable for testing large size equipment. Different types of simulators are described and their pros and cons are discussed. A bounded wave parallel plate type simulator is chosen for it's efficiency and the least environmental impact. Detailed designs are given for 6 m and 10 m parallel plate type wire grid simulators. Electromagnetic fields inside and outside the simulators are computed. Preliminary specifications for a pulse generator required for the simulator are also given. Finally, the electromagnetic fields radiated from the simulator are computed and discussed.

  8. Development of Design Information Template for Nuclear Power Plants for Electromagnetic Pulse (EMP) Effect Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Minyi; Ryu, Hosan; Ye, Songhae; Lee, Euijong [KNHP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    An electromagnetic pulse (EMP) is a transient electromagnetic shock wave that has powerful electric and magnetic fields that can destroy electronic equipment. It is generally well-known that EMPs can cause the malfunction and disorder of electronic equipment and serious damages to electric power systems and communication networks. Research is being carried out to protect nuclear power plants (NPPs) from EMP threats. Penetration routes of EMPs can be roughly categorized into two groups, radioactivity and conductivity. The radioactive effect refers to an impact transmitted to the ground from high-altitude electromagnetic pulses (HEMP). Such an impact may affect target equipment through the point of entry (POE) of the concrete structure of an NPP. The conductive effect refers to induced voltage or current coupled to the NPPs cable structure. The induced voltage and current affect the target equipment via connected cables. All these factors must be considered when taking into account EMP effect analysis for NPPs. To examine all factors, it is necessary to fully understand the schemes of NPPs. This paper presents a four type design information template that can be used to analyze the EMP effect in operating nuclear power plants. In order to analyze of the effects of EMPs on operating NPPs, we must consider both the conductive and radioactive effects on the target (system, equipment, structure). For these reasons, not only the equipment information, but also the information about the structure and the external penetration will be required. We are developing a design information template for robust nuclear design information acquisition. We expect to develop a block diagram on the basis of the template.

  9. Development of Design Information Template for Nuclear Power Plants for Electromagnetic Pulse (EMP) Effect Analysis

    International Nuclear Information System (INIS)

    Kim, Minyi; Ryu, Hosan; Ye, Songhae; Lee, Euijong

    2016-01-01

    An electromagnetic pulse (EMP) is a transient electromagnetic shock wave that has powerful electric and magnetic fields that can destroy electronic equipment. It is generally well-known that EMPs can cause the malfunction and disorder of electronic equipment and serious damages to electric power systems and communication networks. Research is being carried out to protect nuclear power plants (NPPs) from EMP threats. Penetration routes of EMPs can be roughly categorized into two groups, radioactivity and conductivity. The radioactive effect refers to an impact transmitted to the ground from high-altitude electromagnetic pulses (HEMP). Such an impact may affect target equipment through the point of entry (POE) of the concrete structure of an NPP. The conductive effect refers to induced voltage or current coupled to the NPPs cable structure. The induced voltage and current affect the target equipment via connected cables. All these factors must be considered when taking into account EMP effect analysis for NPPs. To examine all factors, it is necessary to fully understand the schemes of NPPs. This paper presents a four type design information template that can be used to analyze the EMP effect in operating nuclear power plants. In order to analyze of the effects of EMPs on operating NPPs, we must consider both the conductive and radioactive effects on the target (system, equipment, structure). For these reasons, not only the equipment information, but also the information about the structure and the external penetration will be required. We are developing a design information template for robust nuclear design information acquisition. We expect to develop a block diagram on the basis of the template

  10. Assessment and mitigation of electromagnetic pulse (EMP) impacts at short-pulse laser facilities

    International Nuclear Information System (INIS)

    Brown, C G Jr; Bond, E; Clancy, T; Dangi, S; Eder, D C; Ferguson, W; Kimbrough, J; Throop, A

    2010-01-01

    The National Ignition Facility (NIF) will be impacted by electromagnetic pulse (EMP) during normal long-pulse operation, but the largest impacts are expected during short-pulse operation utilizing the Advanced Radiographic Capability (ARC). Without mitigation these impacts could range from data corruption to hardware damage. We describe our EMP measurement systems on Titan and NIF and present some preliminary results and thoughts on mitigation.

  11. An overview of EMP effects and their control

    Science.gov (United States)

    Culligan, A. J.

    1985-09-01

    The environments associated with a nuclear detonation are probably the most extreme of all the environments to which an electronic equipment system may be exposed. One of these environments is related to the electromagnetic pulse (EMP) which represents an intense pulse of radiated electromagnetic energy. The endo-atmospheric EMP is generally not considered a major threat in comparison with other nuclear weapon effects related to blast, thermal phenomena, neutrons, and gamma rays. The situation is different with respect to the exo-atmospheric EMP which has the potential to simultaneously damage communication and allied networks over many thousands of square miles. The present paper is concerned with these EMP effects and the possibilities for protecting equipment from EMP. For such a protection, an understanding of the system's electronic topology is essential, and component/circuit susceptibility levels must be specified. Attention is given to the wire grid model of a strike aircraft, and the simulation of the EMP environment.

  12. The EMP excitation of radiation by the pulsed relativistic electron beam

    International Nuclear Information System (INIS)

    Balakirev, V.A.; Sidelnikov, G.L.

    1996-01-01

    The mechanisms of excitation of ultra-wideband electromagnetic pulses (EMP) by short pulses of high-current relativistic electron beams were proposed and investigated. It is shown that the transformation efficiency of the bunch kinetic energy to the excited energy of the EMP can be very significant. (author). 2 figs., 4 refs

  13. The EMP excitation of radiation by the pulsed relativistic electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Balakirev, V A; Sidelnikov, G L [Kharkov Inst. of Physics and Technology (Russian Federation)

    1997-12-31

    The mechanisms of excitation of ultra-wideband electromagnetic pulses (EMP) by short pulses of high-current relativistic electron beams were proposed and investigated. It is shown that the transformation efficiency of the bunch kinetic energy to the excited energy of the EMP can be very significant. (author). 2 figs., 4 refs.

  14. Did high-altitude EMP (electromagnetic pulse) cause the Hawaiian streetlight incident

    Energy Technology Data Exchange (ETDEWEB)

    Vittitoe, C N

    1989-04-01

    Studies of electromagnetic pulse (EMP) effects on civilian and military systems predict results ranging from severe destruction to no damage. Convincing analyses that support either extreme are rare. The Hawaiian streetlight incident associated with the Starfish nuclear burst is the most widely quoted observed damage. We review the streetlight characteristics and estimate the coupling between the Starfish EMP and a particular streetlight circuit identified as one of the few that failed. Evidence indicates that the damage was EMP-generated. The main contributing factors were the azimuthal angle of the circuit relative to the direction of EMP propagation, and the rapid rise of the EMP signal. The azimuthal angle provided coherent buildup of voltage as the EMP swept across the transmission line. The rapid rise allowed substantial excitation before the canceling effects of ground reflections limited the signals. Resulting voltages were at the threshold for causing the observed fuse damage and are consistent with this damage occurring in only some of the strings in the systems. 15 refs., 16 figs., 4 tabs.

  15. The Establishment of Object Selection Criteria for Effect Analysis of Electromagnetic Pulse (EMP) in Operating Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Song Hae; Ryu, Hosun; Kim, Minyi; Lee, Euijong [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    The electromagnetic pulse (EMP) can be used as a strategic weapon by inducing damaging voltage and currents that the electrical circuits are not designed to withstand. EMPs are lethal to electronic systems. All EMP events have three common components: a source, coupling path, and receptor. It can also travel across power grids, destroying electronics as it passes in less than a second. There have been no research studies on the effect analysis for EMP in domestic nuclear power plants and power grids. To ensure the safety of operating nuclear power plants in this environment, the emission of EMP is needed for the effect analysis and safety measures against EMPs. Actually, it is difficult and inefficient to conduct the effect analysis of EMP with all the equipment and systems in nuclear power plants (NPPs). Therefore, this paper presents the results of establishing the object selection criteria for the effect analysis of EMP in operating nuclear power plants through reviewing previous research in the US and the safety related design concepts in domestic NPPs. It is not necessary to ensure the continued operation of the plant in intense multiple EMP environments. The most probable effect of EMP on a modern nuclear power plant is an unscheduled shutdown. EMP may also cause an extended shutdown by the unnecessary activation of some safety related systems. In general, EMP can be considered a nuisance to nuclear plants, but it is not considered a serious threat to plant safety. The results of EMP effect analysis show less possibility of failure in the tested individual equipment. It was also confirmed that there is no possibility of simultaneous failure for devices in charge of the safety shutdown in the NPP.

  16. Bioelectromagnetic effects of EMP: Preliminary findings

    Science.gov (United States)

    Aldrich, T. E.; Easterly, C. E.; Gailey, P. C.; Hamilton, C. B.

    1988-06-01

    Facilities to simulate electromagnetic pulses (EMPs) are used to test military equipment and electrical communications devices for resistance to the effects of an EMP caused by an upper-atmospheric nuclear detonation. The rapid rise time and high field strengths (0.1 to 50 kV/m) of an EMP distinguish it from other electromagnetic phenomena. Certain types of EMP simulators also expose facility operators and members of the public to electromagnetic fields of varying intensity as do other natural sources such as the fields produced near a lightning bolt. Limited biological effects data have been collected to assess the potential EMP health hazards to humans. Evidence from the available database does not establish that EMPs represent either an occupational or a public health hazard. A critique is presented of the EMP research published to date in order to explore its limitations and similarities with related outcome experience from other electromagnetic field research. Laboratory research and multiple years of observations on workers in existing EMP manufacturing and simulation facilities suggest that there are no acute or short-term health effects. The occupational exposure guideline for EMP is 100 kV/m, which is far in excess of usual exposures with EMP simulators.

  17. Effects of nuclear electromagnetic pulse (EMP) on synchronous stability of the electric power system

    International Nuclear Information System (INIS)

    Manweiler, R.W.

    1975-11-01

    The effects of a nuclear electromagnetic pulse (EMP) on the synchronous stability of the electric power transmission and distribution systems are evaluated. The various modes of coupling of EMP to the power system are briefly discussed, with particular emphasis on those perturbations affecting the synchronous stability of the transmission system. A brief review of the fundamental concepts of the stability problem is given, with a discussion of the general characteristics of transient analysis. A model is developed to represent single sets as well as repetitive sets of multiple faults on the distribution systems, as might be produced by EMP. The results of many numerical stability calculations are presented to illustrate the transmission system's response from different types of perturbations. The important parameters of both multiple and repetitive faults are studied, including the dependence of the response on the size of the perturbed area, the fault density, and the effective impedance between the fault location and the transmission system. Both major load reduction and the effect of the opening of tie lines at the time of perturbation are also studied. We conclude that there is a high probability that EMP can induce perturbations on the distribution networks causing a large portion of the transmission network in the perturbed area to lose synchronism. The result would be an immediate and massive power failure

  18. Experimental investigation on EMP effect of SRAM

    International Nuclear Information System (INIS)

    Han Jun; Xie Yanzhao; Zhai Aibin; Yao Zhibin

    2010-01-01

    The response of SRAM with different memory size at different read/write state was studied under EMP environment with pulse width of 50 ns, 350 ns and 1μs.The electric field amplitude of EMP ranges from 2.5 to 40 kV/m. It was found that the upset number has no obvious relation with memory size of SRAM and band width of EMP. The electric field amplitude is the crucial parameter leading to the upset effects. Further more, the upset effects of SRAM at read write state was much more seriously compared to the SRAM was not at read/write state. (authors)

  19. Electromagnetic pulse (EMP) survey of the Idaho State Emergency Operating Center, Boise, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Crutcher, R.I.; Buchanan, M.E.; Jones, R.W.

    1992-02-01

    The purpose of this report is to develop an engineering design package to protect the Federal Emergency Management Agency (FEMA) National Radio System (FNARS) facilities from the effects of high- altitude electromagnetic pulses (HEMPs). This report was developed specifically for the Idaho State Emergency Operating Center (EOC) in Boise, Idaho. It is highly probable that there will be a heavy dependence upon high-frequency (hf) radio communications for long- haul communications following a nuclear attack on the continental United States, should one occur. To maintain the viability of the FEMA hf radio network during such a situation, steps must be taken to protect the FNARS facilities against the effects of HEMP that are likely to be created in a nuclear confrontation. The solution must than be to reduce HEMP-induced stresses on the system by means of tailored retrofit hardening measures using commercial protection devices when available. It is the intent of this report to define the particular hardening measures that will minimize the susceptibility of system components to HEMP effects. To the extent economically viable, protective actions have been recommended for implementation, along with necessary changes or additions, during the period of the FNARS upgrade program. This report addresses electromagnetic pulse (EMP) effects only and disregards any condition in which radiation effects may be a factor. It has been established that, except for the source region of a surface burst, EMP effects of high-altitude bursts are more severe than comparable detonations in either air or surface regions. Any system hardened to withstand the more extreme EMP environment will survive the less severe EMP conditions. The threatening environment will therefore be limited to HEMP situations.

  20. Nuclear EMP: ingredients of an EMP protection engineering methodology

    International Nuclear Information System (INIS)

    Latorre, V.R.; Spogen, L.R. Jr.

    1977-02-01

    A fundamental methodology of electromagnetic pulse (EMP) protection engineering is described. Operations performed within the framework of this methodology are discussed. These operations, along with problem constraints and data, constitute the essential ingredients needed to implement the overall engineering methodology. Basic definitions and descriptions of these essential ingredients are provided. The issues discussed represent the first step in developing a methodology for protecting systems against EMP effects

  1. Pulsed power sources based on MHD generators (A state-of-art review)

    International Nuclear Information System (INIS)

    Das, A.K.; Venkatramani, N.; Rohatgi, V.K.

    1986-01-01

    pulsed Power sources are finding increased applications in powering plasma experiments, CTF devices, investigations of structure of earth's crust or self-contained compact power supplies for military applications. This report reviews the development of magnetohydrodynamic (MHD) power systems for pulsed power applications. The major critical components, which are analysed in detail, include the combustor, high energy fuel development, high field magnet, high power density channel and power conditioning unit. The report concludes that the MHD research has now reached a stage, where it is possible to design and achieve requisite performance from short duration high power compact MHD generators. (author)

  2. The integrated circuit IC EMP transient state disturbance effect experiment method investigates

    International Nuclear Information System (INIS)

    Li Xiaowei

    2004-01-01

    Transient state disturbance characteristic study on the integrated circuit, IC, need from its coupling path outset. Through cable (aerial) coupling, EMP converts to an pulse current voltage and results in the impact to the integrated circuit I/O orifice passing the cable. Aiming at the armament system construction feature, EMP effect to the integrated circuit, IC inside the system is analyzed. The integrated circuit, IC EMP effect experiment current injection method is investigated and a few experiments method is given. (authors)

  3. Nuclear EMP induced chaos

    International Nuclear Information System (INIS)

    Dance, B.

    1983-01-01

    It is anticipated that a single nuclear explosion, of adequate size, on the outside of the atmosphere would generate a pulse of sufficient intensity to damage communications equipment (including telephones, radio transmitters and receivers), and to disrupt main power supplies. This damage could be done by a very intense, short duration electro-magnetic pulse (EMP). The article discusses the generation and history of EMP, the test facilities that are needed for EMP test, and techniques that can be used to harden equipment against EMP. It is also important to protect extensive systems against EMP. The article points out that fibre-optics are very useful, because they are EMP resistant and a single fibre can also carry a very high data rate

  4. EMP Fusion

    OpenAIRE

    KUNTAY, Isık

    2010-01-01

    This paper introduces a novel fusion scheme, called EMP Fusion, which has the promise of achieving breakeven and realizing commercial fusion power. The method is based on harnessing the power of an electromagnetic pulse generated by the now well-developed flux compression technology. The electromagnetic pulse acts as a means of both heating up the plasma and confining the plasma, eliminating intermediate steps. The EMP Fusion device is simpler compared to other fusion devices and this reduces...

  5. Comparative EMP design practices

    International Nuclear Information System (INIS)

    Martin, L.C.

    1975-01-01

    A large amount of effort is devoted to the hardening of systems against various effects. The nuclear electromagnetic pulse (EMP) creates potentially severe protection problems in hardening against electromagnetic effects. Each hardening effort is usually supported through development or application of sets of rules, practices, constraints, etc., which aid in decision-making throughout the design process. Several excerpts from a few sets of EMP design rules and practices taken from relatively independent sources are presented for comparison of essential features and mode of expression. A general objective is to clarify some of the EMP practices present in general EMC work and to encourage further interchange of relevant information. (auth)

  6. Nuclear EMP induced chaos. [Effect of nuclear explosion on power and communication facilities

    Energy Technology Data Exchange (ETDEWEB)

    Dance, B

    1983-04-01

    It is anticipated that a single nuclear explosion, of adequate size, on the outside of the atmosphere would generate a pulse of sufficient intensity to damage communications equipment (including telephones, radio transmitters and receivers), and to disrupt main power supplies. This damage could be done by a very intense, short duration electro-magnetic pulse (EMP). The article discusses the generation and history of EMP, the test facilities that are needed for EMP test, and techniques that can be used to harden equipment against EMP. It is also important to protect extensive systems against EMP. The article points out that fibre-optics are very useful, because they are EMP resistant and a single fibre can also carry a very high data rate.

  7. EMP coupling to ships

    International Nuclear Information System (INIS)

    Deadrick, F.J.; Cabayan, H.S.; Kunz, K.F.; Bevensee, R.M.; Martin, L.C.; Egbert, R.W.

    1980-01-01

    Scale-model tests were conducted to establish the adequacy and limitations of model measurements as tools for predicting electromagnetic pulse (EMP) coupling voltages and currents to the critical antennas, cables, and metallic structures on ships. The scale-model predictions are compared with the results of the full-scale EMP simulation test of the Canadian ASW ship, HMCS Huron. (The EMP coupling predictions in this report were made without prior knowledge of the results of the data from the HMCS Huron tests.) This report establishes that the scale-model tests in conjunction with the data base from EMP coupling modules provides the necessary information for source model development and permits effective, low-cost study of particular system configurations. 184 figures, 9 tables

  8. 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.

  9. Towards Integrated Pulse Detonation Propulsion and MHD Power

    Science.gov (United States)

    Litchford, Ron J.; Thompson, Bryan R.; Lineberry, John T.

    1999-01-01

    The interest in pulse detonation engines (PDE) arises primarily from the advantages that accrue from the significant combustion pressure rise that is developed in the detonation process. Conventional rocket engines, for example, must obtain all of their compression from the turbopumps, while the PDE provides additional compression in the combustor. Thus PDE's are expected to achieve higher I(sub sp) than conventional rocket engines and to require smaller turbopumps. The increase in I(sub sp) and the decrease in turbopump capacity must be traded off against each other. Additional advantages include the ability to vary thrust level by adjusting the firing rate rather than throttling the flow through injector elements. The common conclusion derived from these aggregated performance attributes is that PDEs should result in engines which are smaller, lower in cost, and lighter in weight than conventional engines. Unfortunately, the analysis of PDEs is highly complex due to their unsteady operation and non-ideal processes. Although the feasibility of the basic PDE concept has been proven in several experimental and theoretical efforts, the implied performance improvements have yet to be convincingly demonstrated. Also, there are certain developmental issues affecting the practical application of pulse detonation propulsion systems which are yet to be fully resolved. Practical detonation combustion engines, for example, require a repetitive cycle of charge induction, mixing, initiation/propagation of the detonation wave, and expulsion/scavenging of the combustion product gases. Clearly, the performance and power density of such a device depends upon the maximum rate at which this cycle can be successfully implemented. In addition, the electrical energy required for direct detonation initiation can be significant, and a means for direct electrical power production is needed to achieve self-sustained engine operation. This work addresses the technological issues associated

  10. Effects of induced magnetic field on large scale pulsed MHD generator with two phase flow

    International Nuclear Information System (INIS)

    Ishikawa, M.; Koshiba, Y.; Matsushita, T.

    2004-01-01

    A large pulsed MHD generator 'SAKHALIN' was constructed in Russia (the former Soviet-Union) and operated with solid fuels. The 'SAKHALIN' with the channel length of 4.5 m could demonstrate the electric power output of 510 MW. The effects of induced magnetic field and two phase flow on the shock wave within the 'SAKHALIN' generator have been studied by time dependent, one dimensional analyses. It has been shown that the magnetic Reynolds number is about 0.58 for Run No. 1, and the induced magnetic flux density is about 20% at the entrance and exit of the MHD channel. The shock wave becomes stronger when the induced magnetic field is taken into account, when the operation voltage becomes low. The working gas plasma contains about 40% of liquid particles (Al 2 O 3 ) in weight, and the present analysis treats the liquid particles as another gas. In the case of mono-phase flow, the sharp shock wave is induced when the load voltage becomes small such as 500 V with larger Lorentz force, whereas in the case of two phase flow, the shock wave becomes less sharp because of the interaction with liquid particles

  11. Power system EMP protection. Final report

    International Nuclear Information System (INIS)

    Marable, J.H.; Barnes, P.R.; Nelson, D.B.

    1975-05-01

    Voltage transients induced in electric power lines and control circuits by the electromagnetic pulse (EMP) from high-altitude nuclear detonations may cause widespread power failure and damage in electric power systems. This report contains a parametric study of EMP power line surges and discusses protective measures to minimize their effects. Since EMP surges have considerably greater rates of rise than lightning surges, recommended standards and test procedures are given to assure that surge arresters protect equipment from damage by EMP. Expected disturbances and damage to power systems are reviewed, and actions are presented which distribution companies can take to counter them. These include backup communications methods, stockpiling of vulnerable parts, repair procedures, and dispatcher actions to prevent blackout from EMP-caused instabilities. A long-range program is presented for improving distributors' protection against EMP. This involves employee training, hardware protection for power and control circuits, and improvement of plans for emergency action. (U.S.)

  12. Ultrashort laser pulses and electromagnetic pulse generation in air and on dielectric surfaces

    International Nuclear Information System (INIS)

    Sprangle, P.; Penano, J.R.; Hafizi, B.; Kapetanakos, C.A.

    2004-01-01

    Intense, ultrashort laser pulses propagating in the atmosphere have been observed to emit sub-THz electromagnetic pulses (EMPS). The purpose of this paper is to analyze EMP generation from the interaction of ultrashort laser pulses with air and with dielectric surfaces and to determine the efficiency of conversion of laser energy to EMP energy. In our self-consistent model the laser pulse partially ionizes the medium, forms a plasma filament, and through the ponderomotive forces associated with the laser pulse, drives plasma currents which are the source of the EMP. The propagating laser pulse evolves under the influence of diffraction, Kerr focusing, plasma defocusing, and energy depletion due to electron collisions and ionization. Collective effects and recombination processes are also included in the model. The duration of the EMP in air, at a fixed point, is found to be a few hundred femtoseconds, i.e., on the order of the laser pulse duration plus the electron collision time. For steady state laser pulse propagation the flux of EMP energy is nonradiative and axially directed. Radiative EMP energy is present only for nonsteady state or transient laser pulse propagation. The analysis also considers the generation of EMP on the surface of a dielectric on which an ultrashort laser pulse is incident. For typical laser parameters, the power and energy conversion efficiency from laser radiation to EMP radiation in both air and from dielectric surfaces is found to be extremely small, -8 . Results of full-scale, self-consistent, numerical simulations of atmospheric and dielectric surface EMP generation are presented. A recent experiment on atmospheric EMP generation is also simulated

  13. Strategies, Protections and Mitigations for Electric Grid from Electromagnetic Pulse Effects

    Energy Technology Data Exchange (ETDEWEB)

    Foster, Rita Ann [Idaho National Lab. (INL), Idaho Falls, ID (United States); Frickey, Steven Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-01-01

    The mission of DOE’s Office of Electricity Delivery and Energy Reliability (OE) is to lead national efforts to modernize the electricity delivery system, enhance the security and reliability of America’s energy infrastructure and facilitate recovery from disruptions to the energy supply. One of the threats OE is concerned about is a high-altitude electro-magnetic pulse (HEMP) from a nuclear explosion and eletro-magnetic pulse (EMP) or E1 pulse can be generated by EMP weapons. DOE-OE provides federal leadership and technical guidance in addressing electric grid issues. The Idaho National Laboratory (INL) was chosen to conduct the EMP study for DOE-OE due to its capabilities and experience in setting up EMP experiments on the electric grid and conducting vulnerability assessments and developing innovative technology to increase infrastructure resiliency. This report identifies known impacts to EMP threats, known mitigations and effectiveness of mitigations, potential cost of mitigation, areas for government and private partnerships in protecting the electric grid to EMP, and identifying gaps in our knowledge and protection strategies.

  14. Protecting power equipment against magnetohydrodynamic effects (MHD of electromagnetic pulses (EMP

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2015-01-01

    Full Text Available The article is devoted to the effects of geomagnetic-induced currents (GIC on electrical equipment of power systems and analyzes technical measures for protection against such effects. It is noted that the difference between highaltitude nuclear detonation and solar storm GICs forces applying different methods of electrical equipment protection. It also illustrates that enhancement of transformer immunity to GICs without saturation prevention is not an effective measure to protect the power system. The article offers a special relay designed for fast disconnection of the transformer under GICs.

  15. MHD pilot industrial applications

    International Nuclear Information System (INIS)

    Freeman, M.; Riviere-Wekstein, G.

    1994-01-01

    MHD industrial applications (and their historical developments) are sketched in the fields of nuclear fission, nuclear fusion and marine vehicles propelling. Nuclear fission projects resulted in promising prototypes between 1972 and 1980, especially for liquid-metal MHD generators. All of them have been stopped by the scientific policies of the governments. Nuclear fusion projects used mainly the equilibrium plasma of tokamak type reactors; some military projects used pulsed plasma to perform pulsed MHD generators. Marine vehicle propelling is the most advanced field. By june 1992, the japanese sea-going boat 'Yamato 1' was sailing with two MHD propellers. A few months later, the building of 'Yamato 2' has begun

  16. Methods for Free-Space Ultra-Short Solitary EMP Measurement

    Directory of Open Access Journals (Sweden)

    Petr Drexler

    2006-01-01

    Full Text Available There are some suitable methods for ultra-short solitary electromagnetic pulses (EMP measurement. The EMPs are generated by high power microwave generators. The characteristic of EMPs is high power level (Pmax = 250 MW and very short time duration (tp Î <1, 60> ns. Special requirements for measurement methods are placed because of the specific EMPs properties.Two suitable methods for this application are presented in the paper. The first – calorimetric method, utilizes the thermal impacts of microwave absorption. The second method presented – magneto-optic method, use the Faraday’s magneto-optic effect as a sensor principle. It was realized combined calorimetric sensor and there were made some experimental EMP measurements with good results. The sensor utilizing magneto-optic method is in development.

  17. EMP/GMD Phase 0 Report, A Review of EMP Hazard Environments and Impacts

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, Michael Kelly [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Woodroffe, Jesse Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henderson, Michael Gerard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bos, Randall J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Eric Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kelic, Andjelka [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    The purpose of this study is to determine methods to analyze the hazard environments, impacts, and consequences of different sources of electromagnetic pulse (EMP), including nuclear electromagnetic pulse (NEMP) and geomagnetic disturbance (GMD) on the U.S. electric power infrastructures and to use those methods to determine EMP and GMD events of concern. The study will be carried out in four phases, each of which will provide higher levels of analytic fidelity that focuses on those EMP/GMD sources and events that create significant consequences, or whose consequences are sufficiently uncertain, to require more in-depth study. This study will leverage the best experimental data; device, equipment and system models; and simulation tools currently available. This study focuses primarily on the bulk electric system (BES) including large generating stations, large power transformers, the transmission network, and transmission system protection. Electrical distribution systems may potentially be included, if warranted, after consideration of the consequences for the bulk power system.

  18. Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack: Critical National Infrastructures

    National Research Council Canada - National Science Library

    Foster, Jr., John S; Gjelde, Earl; Graham, William R; Hermann, Robert J; Kluepfel, Henry M; Lawson, Richard L; Soper, Gordon K; Wood, Lowell L; Woodard, Joan B

    2008-01-01

    ...) attack on our critical national infrastructures. An earlier report, Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP), Volume 1: Executive Report (2004...

  19. EMP at the Non-Proliferation Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bell, J. [AWE, Aldermaston (United Kingdom)

    1994-12-31

    This experiment presented an opportunity to field customized equipment designed to detect and record electromagnetic pulse (EMP) emanations from an explosion over a wide frequency range. Any data recorded could be used in conjunction with the seismic methods to further non-proliferation studies. No EMP emanations were detectable from the four sensors deployed outside the tunnel confines.

  20. Effects of electromagnetic pulse exposure on gelatinase of blood-brain barrier in vitro.

    Science.gov (United States)

    Zhou, Yan; Qiu, Lian-Bo; An, Guang-Zhou; Zhou, Jia-Xing; Du, Le; Ma, Ya-Hong; Guo, Guo-Zhen; Ding, Gui-Rong

    2017-01-01

    The biological effects of electromagnetic pulse (EMP) on the brain have been focused on for years. It was reported that gelatinase played an important role in maintaining brain function through regulating permeability in the blood-brain barrier (BBB). To investigate the effects of EMP on gelatinase of BBB, an in vitro BBB model was established using primary cultured rat brain microvascular endothelial cells (BMVEC), astrocytes and half-contact culture of these cells in a transwell chamber. Cultured supernatant and cells were collected at different time points after exposure to EMP (peak intensity 400 kV/m, rise time 10 ns, pulse width 350 ns, 0.5 pps and 200 pulses). Protein levels of cellular gelatinase MMP-2 and MMP-9, and endogenous inhibitor TIMP-1 and TIMP-2 were detected by Western blot. The activity of gelatinase in culture supernatant was detected by gelatin zymography. It was found that compared with the sham-exposed group, the protein level of MMP-2 was significantly increased at 6 h (p < 0.05), and the protein level of its endogenous inhibitor TIMP-2 did not change after EMP exposure. In addition, the protein levels of MMP-9 and its endogenous inhibitor TIMP-1 did not change after EMP exposure. Gelatin zymography results showed that the activity of MMP-2 in the inner pool and the outer pool of the transwell chamber was significantly increased at 6 h after EMP exposure compared with that of the sham group. These results suggested that EMP exposure could affect the expression and activity of MMP-2 in the BBB model.

  1. Hardening techniques for nuclear generated EMPs: Pt. 1

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    This article is intended as an introduction to the protection of electronic equipment against the effects of the electromagnetic pulse (EMP) generated by a nuclear explosion. For explosions at heights above 100 km the energy in the pulse is considerable over areas of many thousands of square metres. This constitutes a major threat to electronic equipments which have not been exposed to the consequences of closer nuclear explosions (namely blast, thermal and nuclear radiation)

  2. Nonequilibrium fluctuations in micro-MHD effects on electrodeposition

    International Nuclear Information System (INIS)

    Aogaki, Ryoichi; Morimoto, Ryoichi; Asanuma, Miki

    2010-01-01

    In copper electrodeposition under a magnetic field parallel to electrode surface, different roles of two kinds of nonequilibrium fluctuations for micro-magnetohydrodynamic (MHD) effects are discussed; symmetrical fluctuations are accompanied by the suppression of three dimensional (3D) nucleation by micro-MHD flows (the 1st micro-MHD effect), whereas asymmetrical fluctuations controlling 2D nucleation yield secondary nodules by larger micro-MHD flows (the 2nd micro-MHD effect). Though the 3D nucleation with symmetrical fluctuations is always suppressed by the micro-MHD flows, due to the change in the rate-determining step from electron transfer to mass transfer, the 2D nucleation with asymmetrical fluctuations newly turns unstable, generating larger micro-MHD flows. As a result, round semi-spherical deposits, i.e., secondary nodules are yielded. Using computer simulation, the mechanism of the 2nd micro-MHD effect is validated.

  3. Role of Off-Line-of-Sight Propagation in Geomagnetic EMP Formation

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Hans W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-05-23

    The author’s synchrotron radiation based 3D geomagnetic EMP code MACSYNC has been used to explore the impact on pulse rise time and air conductivity of EMP propagation paths to the observer that are located off the direct line-of-sight (LOS) between gamma source and observer. This geometry is always present because, for an isotropic source, most the gammas are emitted at an angle with respect to the LOS. Computations for a 1 kt near-surface burst observed from space yield two principal findings: 1. The rise time is generated by the combined actions of a) electron spreading along the LOS due to the Compton electron emission angular distribution folded with electron multiple scattering effects, and b) radiation arrival time spreading due to length differences for different off-LOS propagation paths. The pulse rise time does not depend on the rise time of the conductivity. The conductivity rise time determines the pulse amplitude. 2. One-dimensional legacy EMP codes are inherently incapable of producing the correct pulse shape because they cannot treat the dependence of the conductivity on two dimensions, i.e. the radius from the source and the angle of the propagation path with the LOS. This divergence from one-dimensionality begins at a small fraction of a nanosecond for a sea-level burst. This effect will also be present in high-altitude bursts, however, determination of its onset time and magnitude requires high-altitude computations which have not yet been done.

  4. An Approach for Effect Analysis of Electromagnetic Pulse in Operating NPPs

    International Nuclear Information System (INIS)

    Ryu, Ho Sun; Ye, Song Hae; Kim, Minyi; Lee, Euijong

    2016-01-01

    Recently, there is a growing Electromagnetic Pulse (EMP) threat caused by North Korea’s nuclear weapons and unmanned aerial vehicles (UAVs). KHNP CRI is currently conducting a research project that will evaluate the safety of domestic nuclear power plants (NPPs) against EMP effects and prepare safety measures to counter vulnerable points. We will instead use simulation tools to evaluate the electromagnetic shielding ability and the conductivity of cables through vulnerable points in NPPs. Through a study of electromagnetic simulation techniques and tools, this paper suggests a simulation method for analysis of EMP effects in operating NPPs. Although 3D tools are relatively accurate, is difficult to use only 3D tools to simulate EMP effects for huge and complex structures such as NPPs. It is more efficient in terms of cost and time to use a 3D tool and an EMT tool for the simulation of such structures. We have compared the advantages and disadvantages of various methods and have selected the most appropriate tools; we will proceed in our next paper with the simulation of EMP effects

  5. An Approach for Effect Analysis of Electromagnetic Pulse in Operating NPPs

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ho Sun; Ye, Song Hae; Kim, Minyi; Lee, Euijong [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    Recently, there is a growing Electromagnetic Pulse (EMP) threat caused by North Korea’s nuclear weapons and unmanned aerial vehicles (UAVs). KHNP CRI is currently conducting a research project that will evaluate the safety of domestic nuclear power plants (NPPs) against EMP effects and prepare safety measures to counter vulnerable points. We will instead use simulation tools to evaluate the electromagnetic shielding ability and the conductivity of cables through vulnerable points in NPPs. Through a study of electromagnetic simulation techniques and tools, this paper suggests a simulation method for analysis of EMP effects in operating NPPs. Although 3D tools are relatively accurate, is difficult to use only 3D tools to simulate EMP effects for huge and complex structures such as NPPs. It is more efficient in terms of cost and time to use a 3D tool and an EMT tool for the simulation of such structures. We have compared the advantages and disadvantages of various methods and have selected the most appropriate tools; we will proceed in our next paper with the simulation of EMP effects.

  6. MHD stability regimes for steady state and pulsed reactors

    International Nuclear Information System (INIS)

    Jardin, S.C.; Kessel, C.E.; Pomphrey, N.

    1994-02-01

    A tokamak reactor will operate at the maximum value of β≡2μ 0 /B 2 that is compatible with MHD stability. This value depends upon the plasma current and pressure profiles, the plasma shape and aspect ratio, and the location of nearby conducting structures. In addition, a steady state reactor will minimize its external current drive requirements and thus achieve its maximum economic benefit with a bootstrap fraction near one, I bs /I p ∼ 1, which constrains the product of the inverse aspect ratio and the plasma poloidal beta to be near unity, ε β p ∼ 1. An inductively driven pulsed reactor has different constraints set by the steady-state Ohm's law which relates the plasma temperature and density profiles to the parallel current density. We present the results obtained during the ARIES I, II/IV, and III and the PULSAR reactor studies where these quantities were optimized subject to different design philosophies. The ARIES-II/IV and ARIES-III designs are both in the second stability regime, but differ in requirements on the form of the profiles at the plasma edge, and in the location of the conducting wall. The relation between these, as well as new attractive MHD regimes not utilized in the ARIES or PULSAR studies is also discussed

  7. Experimental research for γ-ray interference threshold effect of high electromagnetic pulse sensor

    International Nuclear Information System (INIS)

    Meng Cui; Chen Xiangyue; Nie Xin; Xiang Hui; Guo Xiaoqiang; Mao Congguang; Cheng Jianping; Ni Jianping

    2007-01-01

    The high electromagnetic pulse (EMP) sensor using optical-fiber to transmit signal can restrain electromagnetic interference. The Compton electrons scattered by γ-ray irradiated from nuclear explosion or nuclear explosion simulator can generate high EMP, γ-ray can penetrate the shielding box and irradiate the integrated circuit directly. The γ-ray irradiation effect includes interference, latch up and burn out, these will make the measurement result unbelievable. In this paper, the experimental method researching the γ-ray irradiation effect of high electromagnetic pulse sensor on Qiangguang-I accelerator is introduced. The γ-ray dose rate interference threshold is 2 x 10 6 Gy/s. (authors)

  8. Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field

    Directory of Open Access Journals (Sweden)

    N. V. Erkaev

    2002-01-01

    Full Text Available Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.

  9. Time-domain simulation and waveform reconstruction for shielding effectiveness of materials against electromagnetic pulse

    International Nuclear Information System (INIS)

    Hu, Xiao-feng; Chen, Xiang; Wei, Ming

    2013-01-01

    Shielding effectiveness (SE) of materials of current testing standards is often carried out by using continuous-wave measurement and amplitude-frequency characteristics curve is used to characterize the results. However, with in-depth study of high-power electromagnetic pulse (EMP) interference, it was discovered that only by frequency-domain SE of materials cannot be completely characterized by shielding performance of time-domain pulsed-field. And there is no uniform testing methods and standards of SE of materials against EMP. In this paper, the method of minimum phase transfer function is used to reconstruct shielded time-domain waveform based on the analysis of the waveform reconstruction method. Pulse of plane waves through an infinite planar material is simulated by using CST simulation software. The reconstructed waveform and simulation waveform is compared. The results show that the waveform reconstruction method based on the minimum phase can be well estimated EMP waveform through the infinite planar materials.

  10. [The effects of electromagnetic pulse on fluidity and lipid peroxidation of mitochondrial membrane].

    Science.gov (United States)

    Wang, Changzhen; Cong, Jianbo; Xian, Hong; Cao, Xiaozhe; Sun, Cunpu; Wu, Ke

    2002-08-01

    To study the effects of intense electromagnetic pulse(EMP) on the biological effects of mitochondrial membrane. Rat liver mitochondrial suspension was exposed to EMP at 60 kV/m level. The changes of membrane lipid fluidity and membrane protein mobility were detected by ESR and spin label technique. Malondialdehyde(MDA) was detected by spectrophotometer. The mobility of membrane protein decreased significantly(P < 0.05). Correlation time (tau c) of control group was (0.501 +/- 0.077) x 10(-9)s, and tau c of EMP group was (0.594 +/- 0.049) x 10(-9)s, indicating that the mobility of protein was restricted. The fluidity of mitochondrial membrane increased significantly(P < 0.05) at the same time. Order parameter(S) of mitochondrial membrane lipid in control group was 0.63 +/- 0.01, while S of EMP group was 0.61 +/- 0.01(P < 0.05). MDA decreased significantly. The mobility and lipid peroxidation of mitochondrial membrane may be disturbed after EMP exposure.

  11. EMP protection procedure for electrical/electronic systems

    International Nuclear Information System (INIS)

    Latorre, V.R.

    1976-01-01

    This paper presents a procedure for the protection engineer to follow in assessing a system with respect to its susceptibility to an electromagnetic pulse (EMP), and in determining whether the system requires protection. If the system is determined to be vulnerable to EMP, the procedure also indicates how to decide upon the most suitable protection scheme. The discussion centers on two flow charts, which illustrate the step-by-step procedure which utilizes the necessary ingredients of EMP protection engineering discussed in a previous paper. The description of the protection procedure is divided into two parts: the first dealing with issues on the macroscopic or large-scale system level, while the second is concerned with operations on the subsystem level or lower

  12. Nuclear EMP induced chaos

    Energy Technology Data Exchange (ETDEWEB)

    Dance, B

    1983-08-01

    In the event of nuclear war, the availability of first class communications facilities and of reliable electricity supplies would be of absolutely vital importance to any of the population surviving the first onslaught not only for their own welfare, but also for the preservation of their nation's retaliation deterrent capability. However, it is to be expected that a single nuclear explosion of adequate size on the outside of the atmosphere would generate a pulse of sufficient intensity to damage communications equipment (including telephones, radio transmitters and receivers) and to interrupt main supplies. The situation caused by electromagnetic pulses (EMP) is discussed.

  13. Extended MHD Effects in High Energy Density Experiments

    Science.gov (United States)

    Seyler, Charles

    2016-10-01

    The MHD model is the workhorse for computational modeling of HEDP experiments. Plasma models are inheritably limited in scope, but MHD is expected to be a very good model for studying plasmas at the high densities attained in HEDP experiments. There are, however, important ways in which MHD fails to adequately describe the results, most notably due to the omission of the Hall term in the Ohm's law (a form of extended MHD or XMHD). This talk will discuss these failings by directly comparing simulations of MHD and XMHD for particularly relevant cases. The methodology is to simulate HEDP experiments using a Hall-MHD (HMHD) code based on a highly accurate and robust Discontinuous Galerkin method, and by comparison of HMHD to MHD draw conclusions about the impact of the Hall term. We focus on simulating two experimental pulsed power machines under various scenarios. We examine the MagLIF experiment on the Z-machine at Sandia National Laboratories and liner experiments on the COBRA machine at Cornell. For the MagLIF experiment we find that power flow in the feed leads to low density plasma ablation into the region surrounding the liner. The inflow of this plasma compresses axial magnetic flux onto the liner. In MHD this axial flux tends to resistively decay, whereas in HMHD a force-free current layer sustains the axial flux on the liner leading to a larger ratio of axial to azimuthal flux. During the liner compression the magneto-Rayleigh-Taylor instability leads to helical perturbations due to minimization of field line bending. Simulations of a cylindrical liner using the COBRA machine parameters can under certain conditions exhibit amplification of an axial field due to a force-free low-density current layer separated by some distance from the liner. This results in a configuration in which there is predominately axial field on the liner inside the current layer and azimuthal field outside the layer. We are currently attempting to experimentally verify the simulation

  14. Simulation methods of nuclear electromagnetic pulse effects in integrated circuits

    International Nuclear Information System (INIS)

    Cheng Jili; Liu Yuan; En Yunfei; Fang Wenxiao; Wei Aixiang; Yang Yuanzhen

    2013-01-01

    In the paper the ways to compute the response of transmission line (TL) illuminated by electromagnetic pulse (EMP) were introduced firstly, which include finite-difference time-domain (FDTD) and trans-mission line matrix (TLM); then the feasibility of electromagnetic topology (EMT) in ICs nuclear electromagnetic pulse (NEMP) effect simulation was discussed; in the end, combined with the methods computing the response of TL, a new method of simulate the transmission line in IC illuminated by NEMP was put forward. (authors)

  15. EMP protection technology interchange

    International Nuclear Information System (INIS)

    Martin, L.C.

    1977-01-01

    Investigation and assessment of the potential degrading and destructive effects associated with the nuclear electromagnetic (EMP) phenomena has created a large technological base. This base is indeed quite broad owing to the unique and system-pervasive character of the EMP. One of the aims of an emerging discipline, such as that associated with EMP, is to provide for adequate transfer and integration of the developing technology into the overall engineering community. The needs of the community and how EMP hardening and protection information can be transferred or exchanged are reviewed. Many of the current and generally available sources of information are listed, examples of interchange methods are provided, and problems of developing specifications, standards, and suitable guidelines for design and incorporation of protection are also discussed

  16. [Effect of electromagnetic pulse irradiation on structure and function of Leydig cells in mice].

    Science.gov (United States)

    Wang, Shui-Ming; Wang, De-Wen; Peng, Rui-Yun; Gao, Ya-Bing; Yang, Yi; Hu, Wen-Hua; Chen, Hao-Yu; Zhang, You-Ren; Gao, Yan

    2003-08-01

    To explore the effect of electromagnetic pulse (EMP) irradiation on structure and function of Leydig cells in mice. One hundred and fourteen male Kunming mice were randomly divided into irradiated and control group, the former radiated generally by 8 x 10(3) V/m, 2 x 10(4) V/m and 6 x 10(4) V/m EMP respectively five times within two minutes. Pathological changes of Leydig cells were observed by light and electron microscope. Serum testosterone (T), luteinizing hormone (LH) and estradiol (E2) were measured dynamically by radioimmunoassay at 6 h, 1 d, 3 d, 7 d, 14 d and 28 d after irradiation. Main pathological changes were edema and vacuolation, swelling of cytoplasmic mitochondria, reduce of lipid droplets, pale staining of most of lipid droplets, and partial or complete cavitation of lipid droplets in Leydig cells within 28 days after EMP radiation. Compared with normal controls, serum T decreased in all in different degrees within 28 days, and dropped significantly at 6 h-14 d, 6 h-7 d and 1 d-28 d after 8 x 10(3) V/m, 2 x 10(4) V/m and 6 x 10(4) V/m EMP irradiation(P < 0.05 or P < 0.01). EMP irradiation caused no significant changes in serum LH and E2. Leydig cells are among those that are the most susceptible to EMP irradiation. EMP irradiation may cause significant injury in structure and function of Leydig cells in mice, whose earlier and continuous effect is bound to affect sexual function and sperm production.

  17. Time-domain modeling for shielding effectiveness of materials against electromagnetic pulse based on system identification

    International Nuclear Information System (INIS)

    Chen, Xiang; Chen, Yong Guang; Wei, Ming; Hu, Xiao Feng

    2013-01-01

    Shielding effectiveness (SE) of materials against electromagnetic pulse (EMP) cannot be well estimated by traditional test method of SE of materials which only consider the amplitude-frequency characteristic of materials, but ignore the phase-frequency ones. In order to solve this problem, the model of SE of materials against EMP was established based on system identification (SI) method with time-domain linear cosine frequency sweep signal. The feasibility of the method in this paper was examined depending on infinite planar material and the simulation research of coaxial test method and windowed semi-anechoic box of materials. The results show that the amplitude-frequency and phase-frequency information of each frequency can be fully extracted with this method. SE of materials against strong EMP can be evaluated with time-domain low field strength (voltage) of cosine frequency sweep signal. And SE of materials against a variety EMP will be predicted by the model.

  18. Performance of the CNEN MHD Blow-Down Loop Facility

    Energy Technology Data Exchange (ETDEWEB)

    Bertolini, E.; Brown, R.; Gasparotto, M.; Gay, P.; Toschi, R. [Laboratorio Conversione Diretta, CNEN, Frascati (Italy)

    1968-11-15

    The CNEN facility has been designed, manufactured and used for alkali-seeded noble gas MHD energy conversion research, as the major experimental effort during the first five-year CNEN Research Programme on MHD. The main specifications and the general arrangement with information on preliminary commissioning tests of some components were given at the Salzburg Symposium. Since then the facility has been successfully commissioned and from March 1967 has been working on MHD experiments. Efforts were made to reduce any adverse effects on the experimental MHD results that were due to inherent limitations of an experimental apparatus (particularly under open-circuit conditions). Great emphasis was placed on problems of caesium vaporization and the mixing with helium, the purity level of the mixture, measurements and the control system. The insulation of the plasma from ground was carefully treated, increasing the ratio between insulator resistance and typical plasma resistance as much as possible. Fluidynamic tests at room and high temperatures have shown that stability in the gas parameters (temperature, pressure and mass flow) can be maintained within few per cent for tens of seconds after a transient, giving a behaviour similar to a continuously running system. The high- temperature, alumina pebble-bed heater has successfully operated, bringing the helium-caesium mixtures up to 2000 Degree-Sign K and up to 4 atm abs pressure, and undergoing seven thermal cycles, for a total of more than 2000 hours operation at top temperature. Preheated generator ducts using alumina as insulator and tantalum for electrodes performed satisfactorily, very much attention having been given in the design to reduction of thermal shocks and to obviating possible paths for caesium leakage and short-circuiting of electrode leads. The pulsed liquid nitrogen precooled magnet has been run for about 50 pulses at high field ( Asymptotically-Equal-To 4.5 tesla) with an operating time of about 10

  19. Radiation effects of electromagnetic pulses on mouse blood-testis barrier

    International Nuclear Information System (INIS)

    Hou Wugang; Zhao Jie; Zhang Yuanqiang

    2005-01-01

    Radiation effects caused by 100 kV/m and 400 kV/m electromagnetic pulse (EMP) irradiations on mouse blood-testis barrier were studied by means of routine HE staining, Lanthanum traced electron microscope and injection of caudal vein with Evans Blue. The EMP irradiation of different dose rates damaged Sertoli's cell and blood-testis barrier of mouse testis in different levels. Severe injuries were observed with the 400 kV/m irradiation group, with apoptosis and necrosis in a large quantity of the spermatogenic cells, shape and structural changes of the Sertoli's cells, and serious injuries to the blood-testis barrier, one day after the irradiation. The basal compartment separated from the adluminal compartment in most of the VIII stage seminiferous epithelium, and a great number of apoptosis and necrosis spermatogenic cells were released into the cavities. Injuries of blood-testis barrier could be observed 21 days after the 400 kV/m irradiation. The injuries of 100 kV/m irradiation groups were less severe than the 400 kV/m groups, in which the damages to the Sertoli's cells, the seminiferous epithelium and blood-testis barrier recovered to some extent 14 days after the irradiation. The authors conclude that EMP irradiation can damage mouse blood-tests barrier. The injuries, and the time for recovery, are related to EMP power intensity. (authors)

  20. Energetic particle effects on global MHD modes

    International Nuclear Information System (INIS)

    Cheng, C.Z.

    1990-01-01

    The effects of energetic particles on MHD type modes are studied by analytical theories and the nonvariational kinetic-MHD stability code (NOVA-K). In particular we address the problems of (1) the stabilization of ideal MHD internal kink modes and the excitation of resonant ''fishbone'' internal modes and (2) the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral-beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n=1 internal kink mode in the hot particle beat space exists even in the absence of core ion finite Larmor radius effect (finite ω *i ). On the other hand, the trapped alpha particles are found to resonantly excite instability of the n=1 internal mode and can lower the critical beta threshold. The circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 23 refs., 5 figs

  1. Development of a new EMP code at LANL

    Science.gov (United States)

    Colman, J. J.; Roussel-Dupré, R. A.; Symbalisty, E. M.; Triplett, L. A.; Travis, B. J.

    2006-05-01

    A new code for modeling the generation of an electromagnetic pulse (EMP) by a nuclear explosion in the atmosphere is being developed. The source of the EMP is the Compton current produced by the prompt radiation (γ-rays, X-rays, and neutrons) of the detonation. As a first step in building a multi- dimensional EMP code we have written three kinetic codes, Plume, Swarm, and Rad. Plume models the transport of energetic electrons in air. The Plume code solves the relativistic Fokker-Planck equation over a specified energy range that can include ~ 3 keV to 50 MeV and computes the resulting electron distribution function at each cell in a two dimensional spatial grid. The energetic electrons are allowed to transport, scatter, and experience Coulombic drag. Swarm models the transport of lower energy electrons in air, spanning 0.005 eV to 30 keV. The swarm code performs a full 2-D solution to the Boltzmann equation for electrons in the presence of an applied electric field. Over this energy range the relevant processes to be tracked are elastic scattering, three body attachment, two body attachment, rotational excitation, vibrational excitation, electronic excitation, and ionization. All of these occur due to collisions between the electrons and neutral bodies in air. The Rad code solves the full radiation transfer equation in the energy range of 1 keV to 100 MeV. It includes effects of photo-absorption, Compton scattering, and pair-production. All of these codes employ a spherical coordinate system in momentum space and a cylindrical coordinate system in configuration space. The "z" axis of the momentum and configuration spaces is assumed to be parallel and we are currently also assuming complete spatial symmetry around the "z" axis. Benchmarking for each of these codes will be discussed as well as the way forward towards an integrated modern EMP code.

  2. [Apoptosis of human lung carcinoma cell line GLC-82 induced by high power electromagnetic pulse].

    Science.gov (United States)

    Cao, Xiao-zhe; Zhao, Mei-lan; Wang, De-wen; Dong, Bo

    2002-09-01

    Electromagnetic pulse (EMP) could be used for sterilization of food and the efficiency is higher than 2450 MHz continuous microwave done. This study was designed to evaluate the effect of electromagnetic pulse (EMP) on apoptosis of human lung carcinoma cell line GLC-82, so that to explore and develop therapeutic means for cancer. The injury changes in GLC-82 cells after irradiated with EMP (electric field intensity was 60 kV/m, 5 pulses/2 min) were analyzed by cytometry, MTT chronometry, and flow cytometry. The immunohistochemical SP staining was used to determine the expressions of bcl-2 protein and p53 protein. The stained positive cells were analyzed by CMIAS-II image analysis system at a magnification 400. All data were analyzed by SPSS8.0 software. EMP could obviously inhibited proliferation and activity of lung carcinoma cell line GLC-82. The absorbance value (A570) of MTT decreased immediately, at 0 h, 1 h, and 6 h after the GLC-82 cells irradiated by EMP as compared with control group. The highest apoptosis rate was found to reach 13.38% by flow cytometry at 6 h after EMP irradiation. Down-regulation of bcl-2 expression and up-regulation of p53 expression were induced by EMP. EMP promotes apoptosis of GLC-82 cells. At same time, EMP can down-regulate bcl-2 expression and up-regulate p53 expression in GLC-82 cells. The bcl-2 and the p53 protein may involve the apoptotic process.

  3. Characteristics of laminar MHD fluid hammer in pipe

    International Nuclear Information System (INIS)

    Huang, Z.Y.; Liu, Y.J.

    2016-01-01

    As gradually wide applications of MHD fluid, transportation as well as control with pumps and valves is unavoidable, which induces MHD fluid hammer. The paper attempts to combine MHD effect and fluid hammer effect and to investigate the characteristics of laminar MHD fluid hammer. A non-dimensional fluid hammer model, based on Navier–Stocks equations, coupling with Lorentz force is numerically solved in a reservoir–pipe–valve system with uniform external magnetic field. The MHD effect is represented by the interaction number which associates with the conductivity of the MHD fluid as well as the external magnetic field and can be interpreted as the ratio of Lorentz force to Joukowsky force. The transient numerical results of pressure head, average velocity, wall shear stress, velocity profiles and shear stress profiles are provided. The additional MHD effect hinders fluid motion, weakens wave front and homogenizes velocity profiles, contributing to obvious attenuation of oscillation, strengthened line packing and weakened Richardson annular effect. Studying the characteristics of MHD laminar fluid hammer theoretically supplements the gap of knowledge of rapid-transient MHD flow and technically provides beneficial information for MHD pipeline system designers to better devise MHD systems. - Highlights: • Characteristics of laminar MHD fluid hammer are discussed by simulation. • MHD effect has significant influence on attenuation of wave. • MHD effect strengthens line packing. • MHD effect inhibits Richardson annular effect.

  4. EDITORIAL: 15th Workshop on MHD Stability Control: 3D Magnetic Field Effects in MHD Control 15th Workshop on MHD Stability Control: 3D Magnetic Field Effects in MHD Control

    Science.gov (United States)

    Buttery, Richard

    2011-08-01

    This annual workshop on MHD Stability Control has been held since 1996 with a focus on understanding and developing control of MHD instabilities for future fusion reactors. The workshop generally covers a wide range of stability topics: from disruptions, to tearing modes, error fields, ELMs, resistive wall modes (RWMs) and ideal MHD. It spans many device types, particularly tokamaks, stellarators and reversed field pinches, to pull out commonalities in the physics and improve understanding. In 2010 the workshop was held on 15-17 November at the University of Wisconsin in Madison and was combined with the annual US-Japan MHD Workshop. The theme was `3D Magnetic Field Effects in MHD Control', with a focus on multidisciplinary sessions exploring issues of plasma response to 3D fields, the manifestation of such fields in the plasma, and how they influence stability. This has been a topic of renewed interest, with utilisation of 3D fields for ELM control now planned in ITER, and a focus on the application of such fields for error field correction, disruption avoidance, and RWM control. Key issues included the physics of the interaction, types of coils and harmonic spectra needed to control instabilities, and subsidiary effects such as braking (or rotating) the plasma. More generally, a wider range of issues were discussed including RWM physics, tearing mode physics, disruption mitigation, ballooning stability, the snowflake divertor concept, and the line tied pinch! A novel innovation to the meeting was a panel discussion session, this year on Neoclassical Toroidal Viscosity, which ran well; more will be tried next year. In this special section of Plasma Physics and Controlled Fusion we present several of the invited and contributed papers from the 2010 workshop, which have been subject to the normal refereeing procedures of the journal. These papers give a sense of the exceptional quality of the presentations at this workshop, all of which may be found at http://fusion.gat.com/conferences/mhd

  5. Sub-grid-scale effects on short-wave instability in magnetized hall-MHD plasma

    International Nuclear Information System (INIS)

    Miura, H.; Nakajima, N.

    2010-11-01

    Aiming to clarify effects of short-wave modes on nonlinear evolution/saturation of the ballooning instability in the Large Helical Device, fully three-dimensional simulations of the single-fluid MHD and the Hall MHD equations are carried out. A moderate parallel heat conductivity plays an important role both in the two kinds of simulations. In the single-fluid MHD simulations, the parallel heat conduction effectively suppresses short-wave ballooning modes but it turns out that the suppression is insufficient in comparison to an experimental result. In the Hall MHD simulations, the parallel heat conduction triggers a rapid growth of the parallel flow and enhance nonlinear couplings. A comparison between single-fluid and the Hall MHD simulations reveals that the Hall MHD model does not necessarily improve the saturated pressure profile, and that we may need a further extension of the model. We also find by a comparison between two Hall MHD simulations with different numerical resolutions that sub-grid-scales of the Hall term should be modeled to mimic an inverse energy transfer in the wave number space. (author)

  6. Nuclear EMP: key suppression device parameters for EMP hardening

    International Nuclear Information System (INIS)

    Durgin, D.L.; Brown, R.M.

    1975-03-01

    The electrical transients induced by EMP exhibit unique characteristics which differ considerably from transients associated with other phenomena such as lightning, switching, and circuit malfunctions. The suppression techniques developed to handle more common transients, though not necessarily the same devices, can be used for EMP damage protection. The suppression devices used for circuit level EMP protection are referred to as Terminal Protection Devices (TPD). Little detailed data describing the response of TPD's to EMP-related transients have been published. While most vendors publish specifications for TPD performance, there is little standardization of parameters and TPD response models are not available. This lack of parameter standardization has resulted in a proliferation of test data that is sometimes conflicting and often not directly comparable. This paper derives and/or defines a consistent set of parameters based on EMP circuit hardening requirements and on measurable component parameters and is concerned only with use of TPD's to prevent permanent damage. Three sets of parameters pertaining to pertinent TPD functional characteristics were defined as follows: standby parameters, protection parameters, and failure parameters. These parameters are used to evaluate a representative sample of TPD's and the results are presented in matrix form to facilitate the selection of devices for specific hardening problems

  7. The electromagnetic pulse (EMP) as a danger for the world of electronics

    International Nuclear Information System (INIS)

    Horak, O.

    1984-01-01

    After discussing the characteristics and formation of a nuclear electromagnetic pulse, the author considers the effects such a pulse would have on various types of electronic systems. Finally he discusses what protection there is against such pulses. (Auth.)

  8. Magnus: A New Resistive MHD Code with Heat Flow Terms

    Science.gov (United States)

    Navarro, Anamaría; Lora-Clavijo, F. D.; González, Guillermo A.

    2017-07-01

    We present a new magnetohydrodynamic (MHD) code for the simulation of wave propagation in the solar atmosphere, under the effects of electrical resistivity—but not dominant—and heat transference in a uniform 3D grid. The code is based on the finite-volume method combined with the HLLE and HLLC approximate Riemann solvers, which use different slope limiters like MINMOD, MC, and WENO5. In order to control the growth of the divergence of the magnetic field, due to numerical errors, we apply the Flux Constrained Transport method, which is described in detail to understand how the resistive terms are included in the algorithm. In our results, it is verified that this method preserves the divergence of the magnetic fields within the machine round-off error (˜ 1× {10}-12). For the validation of the accuracy and efficiency of the schemes implemented in the code, we present some numerical tests in 1D and 2D for the ideal MHD. Later, we show one test for the resistivity in a magnetic reconnection process and one for the thermal conduction, where the temperature is advected by the magnetic field lines. Moreover, we display two numerical problems associated with the MHD wave propagation. The first one corresponds to a 3D evolution of a vertical velocity pulse at the photosphere-transition-corona region, while the second one consists of a 2D simulation of a transverse velocity pulse in a coronal loop.

  9. The development of the time dependence of the nuclear EMP electric field

    International Nuclear Information System (INIS)

    Eng, C.

    2009-01-01

    The nuclear electromagnetic pulse (EMP) electric field calculated with the legacy code CHAP is compared with the field given by an integral solution of Maxwell's equations, also known as the Jefimenko equation, to aid our current understanding on the factors that affect the time dependence of the EMP. For a fair comparison the CHAP current density is used as a source in the Jefimenko equation. At first, the comparison is simplified by neglecting the conduction current and replacing the standard atmosphere with a constant density air slab. The simplicity of the resultant current density aids in determining the factors that affect the rise, peak and tail of the EMP electric field versus time. The three dimensional nature of the radiating source, i.e. sources off the line-of-sight, and the time dependence of the derivative of the current density with respect to time are found to play significant roles in shaping the EMP electric field time dependence. These results are found to hold even when the conduction current and the standard atmosphere are properly accounted for. Comparison of the CHAP electric field with the Jefimenko electric field offers a direct validation of the high-frequency/outgoing wave approximation.

  10. Conversion software for ANSYS APDL 2 FLUENT MHD magnetic file

    International Nuclear Information System (INIS)

    Ghita, G.; Ionescu, S.; Prisecaru, I.

    2016-01-01

    The present paper describes the improvements made to the conversion software for ANSYS APDL 2 FLUENT MHD Magnetic File which is able to extract the data from ANSYS APDL file and write down a file containing the magnetic field data in FLUENT magneto hydro dynamics (MHD) format. The MHD module has some features for the uniform and non uniform magnetic field but it is limited for sinusoidal or pulsed, square wave, having a fixed duty cycle of 50%. The present software, ANSYS APDL 2 FLUENT MHD Magnetic File, suffered major modifications in comparison with the last one. The most important improvement consists in a new graphical interface, which has 3D graphical interface for the input file but also for the output file. Another improvement has been made for processing time, the new version is two times faster comparing with the old one. (authors)

  11. analysis of large electromagnetic pulse simulators using the electric field integral equation method in time domain

    International Nuclear Information System (INIS)

    Jamali, J.; Aghajafari, R.; Moini, R.; Sadeghi, H.

    2002-01-01

    A time-domain approach is presented to calculate electromagnetic fields inside a large Electromagnetic Pulse (EMP) simulator. This type of EMP simulator is used for studying the effect of electromagnetic pulses on electrical apparatus in various structures such as vehicles, a reoplanes, etc. The simulator consists of three planar transmission lines. To solve the problem, we first model the metallic structure of the simulator as a grid of conducting wires. The numerical solution of the governing electric field integral equation is then obtained using the method of moments in time domain. To demonstrate the accuracy of the model, we consider a typical EMP simulator. The comparison of our results with those obtained experimentally in the literature validates the model introduced in this paper

  12. Experimental investigation of MHD effects in a manifold of a downstream circular pipe

    International Nuclear Information System (INIS)

    Xu Zengyu; Pan Chuanjie; Wei Wenhao; Chen Xiaoqiong; Zhang Yanxu

    2001-01-01

    The velocity distribution in the mid-plane of the cross section of a main pipe in the region of a junction is investigated. The result confirms that the MHD-flow near the junction is strongly affected by the junction itself. This holds even if the bypass pipe is closed. The MHD pressure drops are also measured, and a three-dimensional (3D) factor of MHD pressure drop due to manifold effects is obtained with theoretical analysis and comparing with experimental data. The factor is directly proportional to Hartmann number Ha. Two dimensional MHD pressure drop is also discussed

  13. Investigations of MHD activity in ASDEX discharges

    International Nuclear Information System (INIS)

    Stambaugh, R.; Gernhardt, J.; Klueber, O.; Wagner, F.

    1984-06-01

    This report makes a strong attempt to relate some specific observations of MHD activity in ADEX discharges to observations made on the Doublet III and PDX tokamaks and to theoretical work on high β MHD modes at GA and PPPL. Three topics are discussed. The first topic is the detailed analysis of the time history of MHD activity in a β discharge. The β limit discharge in ASDEX is identified as a discharge in which, during constant neutral beam power, β reaches a maximum and then decreases, often to a lower steady level if the heating pulse is long enough. During the L phase of this discharge, the MHD activity observed in the B coils is both a continuous and bursting coupled m >= 1 mode of the 'fishbone' type. When β is rising in the H phase, this mode disappears; only ELMs are present. At βsub(max), a different mode appears, the m=2, n=1 tearing mode, which grows rapidly as β decreases. The second topic is the very new observation of the fishbone-like mode in a discharge heated by combined neutral beam and ion cyclotron heating power. The mode characteristics are modulated by sawtooth oscillations in a manner consistent with the importance of q(0) in the stability of this mode. The third topic is the search for ELM precursors in discharges designed to have no other competing and complicating MHD activity. In these cases nonaxisymmetric precursors to the Hsub(α) spike were observed. Hence, it appears that an MHD mode, rather than an energy balance problem, must be the origin of the ELM. (orig./GG)

  14. The effects of corona on current surges induced on conducting lines by EMP: A comparison of experiment data with results of analytic corona models

    Science.gov (United States)

    Blanchard, J. P.; Tesche, F. M.; McConnell, B. W.

    1987-09-01

    An experiment to determine the interaction of an intense electromagnetic pulse (EMP), such as that produced by a nuclear detonation above the Earth's atmosphere, was performed in March, 1986 at Kirtland Air Force Base near Albuquerque, New Mexico. The results of that experiment have been published without analysis. Following an introduction of the corona phenomenon, the reason for interest in it, and a review of the experiment, this paper discusses five different analytic corona models that may model corona formation on a conducting line subjected to EMP. The results predicted by these models are compared with measured data acquired during the experiment to determine the strengths and weaknesses of each model.

  15. Nuclear pulse. II - Ensuring delivery of the doomsday signal

    Science.gov (United States)

    Broad, W. J.

    1981-06-01

    The ability of the communications systems on which U.S. strategic forces depend to survive the electromagnetic pulse (EMP) effects of a nuclear blast in the upper atmosphere is examined. It is shown that the Bell system telephone network, Autovon, on which much military communication presently depends, is especially vulnerable to EMP; while satellite and microwave communications networks are expected to be more resistant to attack. Satellites are, though, vulnerable to killer-satellite attack. Much promise is seen in the conversion of ground communications links to fiber-optic form, which is inherently highly resistant to EMP. A nuclear bomb detonated 200 miles above Nebraska would affect communications equipment throughout the contiguous U.S. with peak fields of 500,000 volts/meter.

  16. An MHD heat source based on intermetallic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Sadjian, H.; Zavitsanos, P. (General Sciences, Inc., Souderton, PA (United States)); Marston, C.H. (Villanova Univ., PA (United States))

    1991-05-06

    The main objective of this program was the development of an MHD heat source of potential use in Space - Based Multi Megawatt, MHD Power Systems. The approach is based on extension of high temperature chemical/ion release technology developed by the General Sciences, Incorporated (GSI) team and successfully applied in other Space Applications. Solid state reactions have been identified which can deliver energy densities and electrons in excess of those from high energy explosives as well as other conventional fuels. The use of intermetallic reactions can be used to generate hot hydrogen plasma from the reaction, to create a high level of seedant ionization, can be packaged as a cartridge type fuels for discrete pulses. The estimated weight for energizing a (100 MW - 1000 sec) Pulsed MHD Power System can range from 12 to 25 {times} 10{sup 3} kg depending on reaction system and strength of the magnetic field. The program consisted of two major tasks with eight subtasks designed to systematically evaluate these concepts in order to reduce fuel weight requirements. Laboratory measurements on energy release, reaction product identification and levels of ionization were conducted in the first task to screen candidate fuels. The second task addressed the development of a reaction chamber in which conductivity, temperature and pressure were measured. Instrumentation was developed to measure these parameters under high temperature pulsed conditions in addition to computer programs to reduce the raw data. Measurements were conducted at GSI laboratories for fuel weights of up to 120 grams and at the Franklin Research Center* for fuel weights up to 1 kilogram. The results indicate that fuel weight can be scaled using modular packaging. Estimates are presented for fuel weight requirements. 15 refs.

  17. Preventing Electromagnetic Pulse Irradiation Damage on Testis Using Selenium-rich Cordyceps Fungi. A Preclinical Study in Young Male Mice.

    Science.gov (United States)

    Miao, Xia; Wang, Yafeng; Lang, Haiyang; Lin, Yanyun; Guo, Qiyan; Yang, Mingjuan; Guo, Juan; Zhang, Yanjun; Zhang, Jie; Liu, Junye; Liu, Yaning; Zeng, Lihua; Guo, Guozhen

    2017-02-01

    Networked 21st century society, globalization, and communications technologies are paralleled by the rise of electromagnetic energy intensity in our environments and the growing pressure of the environtome on human biology and health. The latter is the entire complement of environmental factors, including the electromagnetic energy and the technologies that generate them, enacting on the digital citizen in the new century. Electromagnetic pulse (EMP) irradiation might have serious damaging effects not only on electronic equipment but also in the whole organism and reproductive health, through nonthermal effects and oxidative stress. We sought to determine whether EMP exposure (1) induces biological damage on reproductive health and (2) the extent to which selenium-rich Cordyceps fungi (daily coadministration) offer protection on the testicles and spermatozoa. In a preclinical randomized study, 3-week-old male BALB/c mice were repeatedly exposed to EMP (peak intensity 200 kV/m, pulse edge 3.5 ns, pulse width 15 ns, 0.1 Hz, and 400 pulses/day) 5 days per week for four consecutive weeks, with or without coadministration of daily selenium-rich Cordyceps fungi (100 mg/kg). Testicular index and spermatozoa formation were measured at baseline and 1, 7, 14, 28, and 60 day time points after EMP exposure. The group without Cordyceps cotreatment displayed decreased spermatozoa formation, shrunk seminiferous tubule diameters, and diminished antioxidative capacity at 28 and 60 days after exposure (p digital citizenship.

  18. Boundary modulation effects on MHD instabilities in Heliotrons

    International Nuclear Information System (INIS)

    Nakajima, N.; Hudson, S.R.; Hegna, C.C.; Nakamura, Y.

    2005-01-01

    In three-dimensional configurations, the confinement region is surrounded by the stochastic magnetic field lines related to magnetic islands or separatrix, leading to the fact that the plasma-vacuum boundary is not so definite compared with tokamaks that the various modulations of the plasma-vacuum boundary will be induced around the stochastic region by a large Shafranov shift of the whole plasma, in especially high-β operations. To examine such the modulation effects of the plasma boundary on MHD instabilities, high-β plasmas allowing a large Shafranov shift are considered in the inward-shifted LHD configurations with the vacuum magnetic axis R ax of 3.6m, for which previous theoretical analyses indicate that pressure-driven modes are significantly more unstable compared with experimental observations. It is shown that the boundary modulation due to a free motion of the equilibrium plasma has not only significant stabilizing effects on ideal MHD instabilities, but also characteristics consistent to experimental observations. (author)

  19. Research report on a study in MHD power generators - end effects

    International Nuclear Information System (INIS)

    Mittal, M.L.

    In MHD devices, there are significant losses due to end effects, boundary layers and instabilities. The present investigations concern the estimation of losses due to end effects. The basic equations and boundary conditions for the analysis of end effects are derived. Using a sinusoidal and exponential termination, at the entrance region of a rectangular MHD channel with continuous electrodes, the end effect phenomenon is analysed. The normal current density on the electrode walls, is examined and the effects of the Hall currents on end losses is discussed. The end effects with diverging electrode walls are also investigated. The normal current distribution on the electrodes and the efficiency are calculated for two different velocity profiles - one with viscosity and the other with source velocity. (K.M.)

  20. Numerical simulation of compact intracloud discharge and generated electromagnetic pulse

    Science.gov (United States)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

    2015-06-01

    Using the concept of the relativistic runaway electron avalanche, numerical simulation of compact intracloud discharge as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-UHF range was conducted. We evaluated the numbers of electrons initiating the avalanche, with which the calculated EMP characteristics are consistent with measured ones. The discharge capable of generating EMPs produces runaway electrons in numbers close to those in the source of terrestrial γ-flashes (TGF) registered in the nearest space, which may be an argument for a joint EMP and TGF source.

  1. On the electromagnetic pulse generated by exo-atmospheric nuclear detonations

    International Nuclear Information System (INIS)

    Leuthaeuser, K.D.

    1983-01-01

    When gamma rays produced by high altitude nuclear weapons explosions interact with the atmosphere they generate an electromagnetic pulse (EMP) propagating towards the earth's surface. The EMP covers large areas of millions of km 2 and reaches peak electric fields of more than 50 kV/m which may couple into all kinds of conducting systems. The present paper deals with a simple model to calculate EMP fields basing on Maxwell's equations. (orig.)

  2. Measures to protect communication systems from EMP effects

    International Nuclear Information System (INIS)

    Stadler, B.

    1977-01-01

    Possible EMP damage in transmitter and receiver elements, including antennas, is dealt with. It is recommendet that these important systems should be installed inside a commercially available Faraday cage for do-it-yourself assembly. (HP) [de

  3. MHD stability, operational limits and disruptions

    International Nuclear Information System (INIS)

    1999-01-01

    The present physics understandings of magnetohydrodynamic (MHD) stability of tokamak plasmas, the threshold conditions for onset of MHD instability, and the resulting operational limits on attainable plasma pressure (beta limit) and density (density limit), and the consequences of plasma disruption and disruption related effects are reviewed and assessed in the context of their application to a future DT burning reactor prototype tokamak experiment such as ITER. The principal considerations covered within the MHD stability and beta limit assessments are (i) magnetostatic equilibrium, ideal MHD stability and the resulting ideal MHD beta limit; (ii) sawtooth oscillations and the coupling of sawtooth activity to other types of MHD instability; (iii) neoclassical island resistive tearing modes and the corresponding limits on beta and energy confinement; (iv) wall stabilization of ideal MHD instabilities and resistive wall instabilities; (v) mode locking effects of non-axisymmetric error fields; (vi) edge localized MHD instabilities (ELMs, etc.); and (vii) MHD instabilities and beta/pressure gradient limits in plasmas with actively modified current and magnetic shear profiles. The principal considerations covered within the density limit assessments are (i) empirical density limits; (ii) edge power balance/radiative density limits in ohmic and L-mode plasmas; and (iii) edge parameter related density limits in H-mode plasmas. The principal considerations covered in the disruption assessments are (i) disruption causes, frequency and MHD instability onset; (ii) disruption thermal and current quench characteristics; (iii) vertical instabilities (VDEs), both before and after disruption, and plasma and in-vessel halo currents; (iv) after disruption runaway electron formation, confinement and loss; (v) fast plasma shutdown (rapid externally initiated dissipation of plasma thermal and magnetic energies); (vi) means for disruption avoidance and disruption effect mitigation; and

  4. MHD stability properties of a system of reduced toroidal MHD equations

    International Nuclear Information System (INIS)

    Maschke, E.K.; Morros Tosas, J.; Urquijo, G.

    1993-01-01

    A system of reduced toroidal magneto-hydrodynamic (MHD) equations is derived from a general scalar representation of the complete MHD system, using an ordering in terms of the inverse aspect ratio ε of a toroidal plasma. It is shown that the energy principle for the reduced equations is identical with the usual energy principle of the complete MHD system, to the appropriate order in ε. Thus, the reduced equations have the same ideal MHD stability limits as the full MHD equations. (authors). 6 refs

  5. Neoclassical MHD equations for tokamaks

    International Nuclear Information System (INIS)

    Callen, J.D.; Shaing, K.C.

    1986-03-01

    The moment equation approach to neoclassical-type processes is used to derive the flows, currents and resistive MHD-like equations for studying equilibria and instabilities in axisymmetric tokamak plasmas operating in the banana-plateau collisionality regime (ν* approx. 1). The resultant ''neoclassical MHD'' equations differ from the usual reduced equations of resistive MHD primarily by the addition of the important viscous relaxation effects within a magnetic flux surface. The primary effects of the parallel (poloidal) viscous relaxation are: (1) Rapid (approx. ν/sub i/) damping of the poloidal ion flow so the residual flow is only toroidal; (2) addition of the bootstrap current contribution to Ohm's laws; and (3) an enhanced (by B 2 /B/sub theta/ 2 ) polarization drift type term and consequent enhancement of the perpendicular dielectric constant due to parallel flow inertia, which causes the equations to depend only on the poloidal magnetic field B/sub theta/. Gyroviscosity (or diamagnetic vfiscosity) effects are included to properly treat the diamagnetic flow effects. The nonlinear form of the neoclassical MHD equations is derived and shown to satisfy an energy conservation equation with dissipation arising from Joule and poloidal viscous heating, and transport due to classical and neoclassical diffusion

  6. Proceedings of the workshop on nonlinear MHD and extended MHD

    International Nuclear Information System (INIS)

    1998-01-01

    Nonlinear MHD simulations have proven their value in interpreting experimental results over the years. As magnetic fusion experiments reach higher performance regimes, more sophisticated experimental diagnostics coupled with ever expanding computer capabilities have increased both the need for and the feasibility of nonlinear global simulations using models more realistic than regular ideal and resistive MHD. Such extended-MHD nonlinear simulations have already begun to produce useful results. These studies are expected to lead to ever more comprehensive simulation models in the future and to play a vital role in fully understanding fusion plasmas. Topics include the following: (1) current state of nonlinear MHD and extended-MHD simulations; (2) comparisons to experimental data; (3) discussions between experimentalists and theorists; (4) /equations for extended-MHD models, kinetic-based closures; and (5) paths toward more comprehensive simulation models, etc. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database

  7. Proceedings of the workshop on nonlinear MHD and extended MHD

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    Nonlinear MHD simulations have proven their value in interpreting experimental results over the years. As magnetic fusion experiments reach higher performance regimes, more sophisticated experimental diagnostics coupled with ever expanding computer capabilities have increased both the need for and the feasibility of nonlinear global simulations using models more realistic than regular ideal and resistive MHD. Such extended-MHD nonlinear simulations have already begun to produce useful results. These studies are expected to lead to ever more comprehensive simulation models in the future and to play a vital role in fully understanding fusion plasmas. Topics include the following: (1) current state of nonlinear MHD and extended-MHD simulations; (2) comparisons to experimental data; (3) discussions between experimentalists and theorists; (4) /equations for extended-MHD models, kinetic-based closures; and (5) paths toward more comprehensive simulation models, etc. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  8. Initial assessment of the MHD stability of TMX-U

    International Nuclear Information System (INIS)

    Nexsen, W.E.

    1983-01-01

    In its operation to date TMX-U has reached values of beta which, for all except the hot electron beta, are close to the proposal values and has not encountered MHD stability problems. The hot electron beta values are presently limited by gyrotron output power and pulse length as well as ion confinement time. Further exploration of stability awaits full thermal barrier operation

  9. Endothelial microparticles (EMP in physiology and pathology

    Directory of Open Access Journals (Sweden)

    Ewa Sierko

    2015-08-01

    Full Text Available Endothelial microparticles (EMP are released from endothelial cells (ECs in the process of activation and/or apoptosis. They harbor adhesive molecules, enzymes, receptors and cytoplasmic structures and express a wide range of various constitutive antigens, typical for ECs, at their surface. Under physiological conditions the concentration of EMP in the blood is clinically insignificant. However, it was reported that under pathological conditions EMP concentration in the blood might slightly increase and contribute to blood coagulation, angiogenesis and inflammation. It has been shown that EMP directly and indirectly contribute to the activation of blood coagulation. Endothelial microparticles directly participate in blood coagulation through their surface tissue factor (TF – a major initiator of blood coagulation. Furthermore, EMP exhibit procoagulant potential via expression of negatively charged phospholipids at their surface, which may promote assembly of coagulation enzymes (TF/VII, tenases and prothrombinase complexes, leading to thrombus formation. In addition, they provide a binding surface for coagulation factors: IXa, VIII, Va and IIa. Moreover, it is possible that EMP transfer TF from TF-bearing EMP to activated platelets and monocytes by binding them through adhesion molecules. Also, EMP express von Willebrand factor, which may facilitate platelet aggregation. Apart from their procoagulant properties, it was demonstrated that EMP may express adhesive molecules and metalloproteinases (MMP-2, MMP-9 at their surface and release growth factors, which may contribute to angiogenesis. Additionally, surface presence of C3 and C4 – components of the classical pathway – suggests pro-inflammatory properties of these structures. This article contains a summary of available data on the biology and pathophysiology of endothelial microparticles and their potential role in blood coagulation, angiogenesis and inflammation.

  10. Effects of a sheared toroidal rotation on the stability boundary of the MHD modes in the tokamak edge pedestal

    International Nuclear Information System (INIS)

    Aiba, N.; Tokuda, S.; Oyama, N.; Ozeki, T.; Furukawa, M.

    2009-01-01

    Effects of a sheared toroidal rotation are investigated numerically on the stability of the MHD modes in the tokamak edge pedestal, which relate to the type-I edge-localized mode. A linear MHD stability code MINERVA is newly developed for solving the Frieman-Rotenberg equation that is the linear ideal MHD equation with flow. Numerical stability analyses with this code reveal that the sheared toroidal rotation destabilizes edge localized MHD modes for rotation frequencies which are experimentally achievable, though the ballooning mode stability changes little by rotation. This rotation effect on the edge MHD stability becomes stronger as the toroidal mode number of the unstable MHD mode increases when the stability analysis was performed for MHD modes with toroidal mode numbers smaller than 40. The toroidal mode number of the unstable MHD mode depends on the stabilization of the current-driven mode and the ballooning mode by increasing the safety factor. This dependence of the toroidal mode number of the unstable mode on the safety factor is considered to be the reason that the destabilization by toroidal rotation is stronger for smaller edge safety factors.

  11. Effects of global MHD instability on operational high beta-regime in LHD

    International Nuclear Information System (INIS)

    Watanabe, K.Y.; Sakakibara, S.; Narushima, Y.; Funaba, H.; Narihara, K.; Tanaka, K.; Toi, K.; Ohdachi, S.; Kaneko, O.; Yamada, H.; Nakajima, N.; Yamada, I.; Kawahata, K.; Tokuzawa, T.; Komori, A.; Yamaguchi, T.; Suzuki, Y.; Cooper, W.A.; Murakami, S.

    2005-01-01

    In the Large Helical device (LHD), the operational highest averaged beta value has been expanded from 3.2% to 4% in last two years by increasing the heating capability and exploring a new magnetic configuration with a high aspect ratio. Although the MHD stability properties are considered to be unfavourable in the new high aspect configuration, the heating efficiency due to neutral beams and the transport properties are expected to be favourable in a high beta range. In order to make clear the effect of the global ideal MHD unstable mode on the operational regimes in helical systems, specially the beta gradients in the peripheral region and the beta value, the MHD analysis and the transport analysis are done in a high beta range up to 4% in LHD. In a high beta range of more than 3%, the maxima of the observed thermal pressure gradients in the peripheral region are marginally stable to a global ideal MHD instability. Though a gradual degradation of the local transport in the region has been observed as beta increases, a disruptive degradation of the local transport does not appear in the beta range up to 4%. (author)

  12. Closed cycle MHD specialist meeting. Progress report, 1971--1972

    International Nuclear Information System (INIS)

    Rietjens, L.H.

    1972-04-01

    Abstracts of the conference papers on closed cycle MHD research are presented. The general areas of discussion are the following: results on closed cycle experiments; plasma properties, and instabilities and stabilization in nonequilibrium plasmas; loss mechanisms, current distributions, electrode effects, boundary layers, and gas dynamic effects; and design concepts of large MHD generators, and nuclear MHD power plants. (GRA)

  13. Effect of electromagnetic coupling on MHD flow in the manifold of fusion liquid metal blanket

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; Meng, Zi; Feng, Jingchao; He, Qingyun

    2014-10-15

    In fusion liquid metal (LM) blanket, magnetohydrodynamics (MHD) effects will dominate the flow patterns and the heat transfer characteristics of the liquid metal flow. Manifold is a key component in LM blanket in charge of distributing or collecting the liquid metal coolant. In this region, the complex three dimensional MHD phenomena will be occurred, and the velocity, pressure and flow rate distributions may be dramatically influenced. One important aspect is the electromagnetic coupling effect resulting from an exchange of electric currents between two neighboring fluid domains that can lead to modifications of flow distribution and pressure drop compared to that in electrical separated channels. Understanding the electromagnetic coupling effect in manifold is necessary to optimize the liquid metal blanket design. In this work, a numerical study was carried out to investigate the effect of electromagnetic coupling on MHD flow in a manifold region. The typical manifold geometry in LM blanket was considered, a rectangular supply duct entering a rectangular expansion area, finally feeding into 3 rectangular parallel channels. This paper investigated the effect of electromagnetic coupling on MHD flow in a manifold region. Different electromagnetic coupling modes with different combinations of electrical conductivity of walls were studied numerically. The flow distribution and pressure drop of these modes have been evaluated.

  14. Magnetohydrodynamic (MHD) power generation

    International Nuclear Information System (INIS)

    Chandra, Avinash

    1980-01-01

    The concept of MHD power generation, principles of operation of the MHD generator, its design, types, MHD generator cycles, technological problems to be overcome, the current state of the art in USA and USSR are described. Progress of India's experimental 5 Mw water-gas fired open cycle MHD power generator project is reported in brief. (M.G.B.)

  15. Liquid blanket MHD effects experimental results from LMEL facility at SWIP

    International Nuclear Information System (INIS)

    Xu Zengyu; Pan Chuanjie; Liu Yong; Pan Chuanhong; Reed, C.B.

    2007-01-01

    The self-cooled /helium-cooled liquid metal blanket concept is an attractive ITER and DEMO blanket candidate as it has low operating pressure, simplicity, and a convenient tritium breeding cycle. But MHD pressure drop remains a key issue, especially in ducts with flow channel inserts (FCI), where the reduction in MHD pressure drop is difficult to predict with existing tools, and there are no available experimental data to check current predictions. To understand well various kinds of MHD effects, it is important for us to analyze and understand FCI effects. In this paper, we present measurements of the MHD effects due to off normal power shutdown, two-dimensional effects due to channel velocity profiles, three-dimensional effects caused by manifolds, and surface/bulk instability effects as a result of insulator coating imperfections. These results were collected from the Liquid Metal Experimental Loop (LMEL) facility at Southwestern Institute of Physics, China and in collaboration with Argonne National Laboratory, US under an umbrella of the People's Republic of China/United States program of cooperation in magnetic fusion. Some results were observed for the first time, such as two dimensional effects and instabilities due to insulator coating imperfections. The experiments were conducted under the following conditions: a uniform magnetic field volume of 80 x 170 x 740 mm and a maximum value of magnetic field, B 0 , of 2 Tesla. The mean flow velocity v 0 was measured with an electromagnetic (EM) flow meter (error of 1.2%); a Liquid-metal Electro-magnetic Velocity Instrument (LEVI) was provided by Argonne National Laboratory. The flow was driven by two Electro-magnetic (EM) pumps (6.5+11.6 m3/h); the operating temperature was 85 centigrade degree due to self-heating by the EM pump and friction of the fluid against the loop piping. Experimental parameters were: Hartmann number, M, up to 3500, velocity v 0 up to 1.2 m/s under magnetic field, and B 0 =1.95 Tesla

  16. NON-IDEAL MHD EFFECTS AND MAGNETIC BRAKING CATASTROPHE IN PROTOSTELLAR DISK FORMATION

    International Nuclear Information System (INIS)

    Li Zhiyun; Krasnopolsky, Ruben; Shang Hsien

    2011-01-01

    Dense, star-forming cores of molecular clouds are observed to be significantly magnetized. A realistic magnetic field of moderate strength has been shown to suppress, through catastrophic magnetic braking, the formation of a rotationally supported disk (RSD) during the protostellar accretion phase of low-mass star formation in the ideal MHD limit. We address, through two-dimensional (axisymmetric) simulations, the question of whether realistic levels of non-ideal effects, computed with a simplified chemical network including dust grains, can weaken the magnetic braking enough to enable an RSD to form. We find that ambipolar diffusion (AD), the dominant non-ideal MHD effect over most of the density range relevant to disk formation, does not enable disk formation, at least in two dimensions. The reason is that AD allows the magnetic flux that would be dragged into the central stellar object in the ideal MHD limit to pile up instead in a small circumstellar region, where the magnetic field strength (and thus the braking efficiency) is greatly enhanced. We also find that, on the scale of tens of AU or more, a realistic level of Ohmic dissipation does not weaken the magnetic braking enough for an RSD to form, either by itself or in combination with AD. The Hall effect, the least explored of these three non-ideal MHD effects, can spin up the material close to the central object to a significant, supersonic rotation speed, even when the core is initially non-rotating, although the spun-up material remains too sub-Keplerian to form an RSD. The problem of catastrophic magnetic braking that prevents disk formation in dense cores magnetized to realistic levels remains unresolved. Possible resolutions of this problem are discussed.

  17. Effect of chemical reaction on unsteady MHD free convective two ...

    African Journals Online (AJOL)

    The effect of flow parameters on the coefficient of skin friction, Nusselt number and Sherwood number are also tabulated and discussed appropriately. It was observed that the increase in chemical reaction coefficient/parameter suppresses both velocity and concentration profiles. Keywords: Chemical Reaction, MHD, ...

  18. Qualification of MHD effects in dual-coolant DEMO blanket and approaches to their modelling

    International Nuclear Information System (INIS)

    Mas de les Valls, E.; Batet, L.; Medina, V. de; Fradera, J.; Sedano, L.A.

    2011-01-01

    Design refinements of vertical insulated banana-shaped liquid metal channels are being considered as a progress of conceptual design of dual-coolant liquid metal blankets (DEMO specifications). Among them: (a) optimised channel geometry and (b) improvements on flow channel inserts. Progress of channel conceptual design is conducted in parallel with underlying physics of MHD models in diverse aspects: (1) MHD models, (2) MHD turbulence, (3) LM buoyancy effects, (4) three-dimensional flows, and (5) LM/FCI/wall electrical and thermal coupling; in order to progress on common liquid metal flow characterisation, pressure drop and three-dimensional flows. The analyses are assumed as extension of those previous carried out for the DCLL blankets for new design refinements. At the present stage of the conceptual design progress, a preliminary thermofluid MHD study is of crucial interest for further design improvements and future detailed modelling. The paper overviews the ongoing modelling studies, making model refinements explicit, and anticipates some modelling results.

  19. Some Fluid Dynamic Effects in Large-Scale MHD Generators

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, J. C.R. [University of Warwick, Coventry (United Kingdom)

    1966-10-15

    At the present time we are unable to carry out a complete analysis of the fluid dynamics and electrodynamics of an MHD generator. However, various aspects of the behaviour of an MHD generator may be examined by the use of simplified models, for example: (1) one-dimensional gas dynamics (Louis et al. 1964); (2) the current distribution can be found if the velocity is assumed constant across the duct (Witalis, 1965); (3) the skin friction and heat transfer to the walls can be calculated by boundary layer analysis if the flow is assumed to be laminar (Kerrebrock, 1961), and (4) a complete description of the velocity and current distribution across the duct can be given if the flow is assumed to be uniform, laminar, incompressible and not varying in the flow direction (Hunt and Stewartson, 1965). Taken together, these and other models will enable us to describe most of the effects in an MHD generator. In this paper another simplification is considered in which the electromagnetic forces are assumed to be much larger than the inertial forces. The ratio of these two forces is measured by the parameter, S = aB{sup 2}{sub 0}d/pU, where o is the conductivity, B{sub 0} the magnetic field, d the width of the duct, p the density and U the mean velocity. Thus S >> 1. We also assume that the magnetic Reynolds number is very much less than one. In the largest experimental generators now being built S {approx} 2 . Thus, though the results of this model are not immediately applicable, they should indicate the effects of increasing the magnetic field strength and the size of MHD generators. When S >> 1, one can can consider the duct to be divided into 2 regions: (1) a core region where electromagnetic forces are balanced by the pressure gradient and where inertial as well as viscous forces are negligible, and (2) boundary layers on the walls where again inertial forces are negligible but where the viscous, electromagnetic and pressure forces are of the same order. We show how it is

  20. Efficient process migration in the EMPS multiprocessor system

    NARCIS (Netherlands)

    van Dijk, G.J.W.; Gils, van M.J.

    1992-01-01

    The process migration facility in the Eindhoven multiprocessor system (EMPS) is presented. In the EMPS system, mailboxes are used for interprocess communication. These mailboxes provide transparency of location for communicating processes. The major advantages of mailbox communication in the EMPS

  1. Generalized reduced MHD equations

    International Nuclear Information System (INIS)

    Kruger, S.E.; Hegna, C.C.; Callen, J.D.

    1998-07-01

    A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general toroidal configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson

  2. MHD mode evolutions prior to minor and major disruptions in SST-1 plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dhongde, Jasraj; Pradhan, Subrata, E-mail: pradhan@ipr.res.in; Bhandarkar, Manisha

    2017-01-15

    Highlights: • Observation of different regimes of MHD phenomena in SST-1 plasma. • MHD mode (m/n = 1/1, m/n = 2/1) evolutions prior to minor and major disruptions in SST-1 plasma. • MHD mode characteristics such as mode frequency, mode number, island width etc. in different regimes. - Abstract: Steady State Superconducting Tokamak (SST-1) is a medium size Tokamak (R{sub 0} = 1.1 m, a = 0.2 m, B{sub T} = 1.5T, Ip ∼ 110 kA) in operation at the Institute for Plasma Research, India. SST-1 uniquely experiments large aspect ratio (∼5.5) plasma in different operation regimes. In these experiments, repeatable characteristic MHD phenomena have been consistently observed. As the large aspect ratio plasma pulse progresses, these MHD phenomena display minor-major disruptions ably indicated in Mirnov oscillations, Mirnov oscillations with saw teeth and locked modes etc. Even though somewhat similar observations have been found in some other machines, these observations are found for the first time in large aspect ratio plasma of SST-1. This paper elaborates the magnetic field perturbations and mode evolutions due to MHD activities from Mirnov coils (poloidal and toroidal), Soft X-ray diagnostics, ECE diagnostics etc. This work further, for the first time reports quantitatively different regimes of MHD phenomena observed in SST-1 plasma, their details of mode evolutions characteristics as well as the subsequently observed minor, major disruptions supported with the physical explanations. This study will help developing disruption mitigation and avoidance scenarios for having better confinement plasma experiments.

  3. Soret and Hall effects on unsteady MHD free convection flow of ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... effects on unsteady MHD free convection flow of radiating and chemically reactive fluid ... Expressions for shear stress, rate of heat transfer and rate of mass transfer at the plate ...

  4. Some effects of MHD activity on impurity transport in the PBX tokamak

    International Nuclear Information System (INIS)

    Ida, K.; Fonck, R.J.; Hulse, R.A.; LeBlanc, B.

    1985-10-01

    The effects of MHD activity on intrinsic impurity transport are studied in ohmic discharges of the Princeton Beta Experiment (PBX) by measuring of the Z/sub eff/ profile from visible bremsstrahlung radiation and the spectral line intensities from ultraviolet spectroscopy. A diffusive/convective transport model, including an internal disruption model, is used to simulate the data. The Z/sub eff/ profile with no MHD activity is fitted with a strong inward convection, characterized by a peaking parameter c/sub v/ (= -a 2 v/2rD) = 11 (3.5, +4.5). At the onset of MHD activity (a large m = 1 n = 1 oscillation followed by sawteeth), this strongly peaked profile is flattened and subsequently reaches a new quasi-equilibrium shape. This profile is characterized by reduced convection [c/sub v/ = 3.6 (-1.1, +1.6), D = 1.4 (-0.7, +5.6) x 10 4 cm 2 /s], in addition to the particle redistribution which accompanies the sawtooth internal disruptions. 10 figs

  5. Experimental study of MHD effects on turbulent flow of flibe simulant fluid in a circular pipe

    International Nuclear Information System (INIS)

    Takeuchi, Junichi; Morley, N.B.; Abdou, M.A.; Satake, Shin-ichi; Yokomine, Takehiko

    2007-01-01

    Experimental studies of MHD turbulent pipe flow of Flibe simulant fluid have been conducted as a part of US-Japan JUPITER-II collaboration. Flibe is considered as a promising candidate for coolant and tritium breeder in some fusion reactor design concepts because of its low electrical conductivity compared to liquid metals. This reduces the MHD pressure drop to a negligible level; however, turbulence can be significantly suppressed by MHD effects in fusion reactor magnetic field conditions. Heat transfer in the Flibe coolant is characterized by its high Prandtl number. In order to achieve sufficient heat transfer and to prevent localized heat concentration in a high Prandtl number coolant, high turbulence is essential. Even though accurate prediction of the MHD effects on heat transfer for high Prandtl number fluids in the fusion environment is very important, reliable data is not available. In these experiments, an aqueous solution of potassium hydroxide is used as a simulant fluid for Flibe. This paper presents the experimental results obtained by flow field measurement using particle image velocimetry (PIV) technique. The PIV measurements provide 2-dimensional 2-velocity component information on the MHD flow field. The test section is a circular pipe with 89 mm inner diameter and 7.0 m in length, which is 79 times pipe diameter. This relatively large diameter pipe is selected in order to maximize the MHD effects measured by Hartmann number (Ha=BL(sigma/mu)1/2), and to allow better resolution of the flow in the near-wall region. The test section is placed under maximum 2 Tesla magnetic fields for 1.4m of the axial length. The hydrodynamic developing length under the magnetic field is expected to be 1.2 m. In order to apply PIV technique in the magnetic field condition, special optical devices and visualization sections were created. PIV measurements are performed for Re = 11600 with variable Hartmann numbers. The turbulence statistics of the MHD turbulent flow

  6. Wavelet-Based Signal Processing of Electromagnetic Pulse Generated Waveforms

    National Research Council Canada - National Science Library

    Ardolino, Richard S

    2007-01-01

    This thesis investigated and compared alternative signal processing techniques that used wavelet-based methods instead of traditional frequency domain methods for processing measured electromagnetic pulse (EMP) waveforms...

  7. A research program to assess the impact of the electromagnetic pulse on electric power systems

    Science.gov (United States)

    McConnell, B. W.; Barnes, P. R.

    A strong electromagnetic pulse (EMP) with an electric-field component on the order of tens of kilovolts per meter is produced by a nuclear detonation in or above the atmosphere. This paper presents an overview and a summary of the results to date of a program formulated to address the research and development of technologies and systems required to assess and reduce the impact of EMP on electric power systems. The technologies and systems being considered include simulation models, methods of assessment, definition of required experiments and data, development of protective hardware, and the creation or revision of operating and control procedures. Results to date include the development of relatively simple unclassified EMP environment models, the development of methods for extending EMP coupling models to the large transmission and distribution network associated with the electric power system, and the performance of a parametric study of HEMP induced surges using an appropriate EMP environment. An experiment to investigate the effect of corona on the coupling of EMP to conductors has been defined and has been performed in an EMP simulator. Experiments to determine the response of key components to simulated EMP surges and an investigation of the impact of steep-front, short-duration impulse on a selected number of the insulation systems used in electric power systems apparatus are being performed.

  8. Neoclassical MHD descriptions of tokamak plasmas

    International Nuclear Information System (INIS)

    Callen, J.D.; Kim, Y.B.; Sundaram, A.K.

    1988-01-01

    Considerable progress has been made in extending neoclassical MHD theory and in exploring the linear instabilities, nonlinear behavior and turbulence models it implies for tokamak plasmas. The areas highlighted in this paper include: extension of the neoclassical MHD equations to include temperature-gradient and heat flow effects; the free energy and entropy evolution implied by this more complete description; a proper ballooning mode formalism analysis of the linear instabilities; a new rippling mode type instability; numerical simulation of the linear instabilities which exhibit a smooth transition from resistive ballooning modes at high collisionality to neoclassical MHD modes at low collisionality; numerical simulation of the nonlinear growth of a single helicity tearing mode; and a Direct-Interaction-Approximation model of neoclassical MHD turbulence and the anomalous transport it induces which substantially improves upon previous mixing length model estimates. 34 refs., 2 figs

  9. MHD Program Plan, FY 1992

    International Nuclear Information System (INIS)

    1991-10-01

    The current MHD program being implemented is a result of a consensus established in public meetings held by the Department of Energy in 1984. Essential elements of the current program include: (1) develop technical and environmental data for the integrated MHD topping cycle system through POC testing (1,000 hours); (2) develop technical and environmental data for the integrated MHD bottoming cycle sub system through POC testing (4,000 hours); (3) design, construct, and operate a seed regeneration POC facility (SRPF) capable of processing spent seed materials from the MHD bottoming cycle; (4) prepare conceptual designs for a site specific MHD retrofit plant; and (5) continue system studies and supporting research necessary for system testing. The current MHD program continues to be directed toward coal fired power plant applications, both stand-alone and retrofit. Development of a plant should enhance the attractiveness of MHD for applications other than electrical power. MHD may find application in electrical energy intensive industries and in the defense sector

  10. Taking in account the electromagnetic pulses in study of a material or system

    International Nuclear Information System (INIS)

    Jeannolle, J.

    1985-01-01

    High altitude nuclear bursts generate extremely short and large magnitude electromagnetic pulses (EMP). Electronic circuits which are commonly used nowadays are directly threatened by such an effect. This effect is so important that it has the characteristic to cover large areas, as large as a whole country. For an equipment or a system to stand against such an electromagnetic threat without being considerably disturbed, it is advised to take into account particular protections from the outset of the design phase and during the production phase, that is to say to ensure its hardening. Taking into account and ensuring the EMP protection of an equipment or a system, the Telecommunications Division (DTC) of Thomson-CSF has been devoting to for a number of years. The experience acquired through various studies and production work has allowed a thorough definition of the main steps required in an EMP hardening task: - hardening goal definition; - hardening study and design; - hardening carrying out; - design and production of EMP environment simulators; - hardening validation; - maintenance. This paper describes for each one of these steps: - which approach is undertaken; - which questions are raised; - which documents to constitute [fr

  11. Effect of Surface Roughness on MHD Couple Stress Squeeze-Film Characteristics between a Sphere and a Porous Plane Surface

    Directory of Open Access Journals (Sweden)

    M. Rajashekar

    2012-01-01

    Full Text Available The combined effects of couple stress and surface roughness on the MHD squeeze-film lubrication between a sphere and a porous plane surface are analyzed, based upon the thin-film magnetohydrodynamic (MHD theory. Using Stoke’s theory to account for the couple stresses due to the microstructure additives and the Christensen’s stochastic method developed for hydrodynamic lubrication of rough surfaces derives the stochastic MHD Reynolds-type equation. The expressions for the mean MHD squeeze-film pressure, mean load-carrying capacity, and mean squeeze-film time are obtained. The results indicate that the couple stress fluid in the film region enhances the mean MHD squeeze-film pressure, load-carrying capacity, and squeeze-film time. The effect of roughness parameter is to increase (decrease the load-carrying capacity and lengthen the response time for azimuthal (radial roughness patterns as compared to the smooth case. Also, the effect of porous parameter is to decrease the load-carrying capacity and increase the squeeze-film time as compared to the solid case.

  12. Protecting the Power Grid From Electromagnetic Pulses

    Science.gov (United States)

    Simpson, Sarah

    2004-10-01

    A nuclear explosion high in the Earth's atmosphere does no immediate known harm to living things, but the resulting electromagnetic pulse (EMP) from a single detonation could degrade 70 percent or more of the country's electrical service in an instant, warns the Commission to Assess the Threat to the United States from Electromagnetic Pulse Attack, which presented its findings to the U.S. Congress in July.

  13. Free convection effects and radiative heat transfer in MHD Stokes ...

    Indian Academy of Sciences (India)

    The present note deals with the effects of radiative heat transfer and free convection in MHD for a flow of an electrically conducting, incompressible, dusty viscous fluid past an impulsively started vertical non-conducting plate, under the influence of transversely applied magnetic field. The heat due to viscous dissipation and ...

  14. Analyses of MHD instabilities

    International Nuclear Information System (INIS)

    Takeda, Tatsuoki

    1985-01-01

    In this article analyses of the MHD stabilities which govern the global behavior of a fusion plasma are described from the viewpoint of the numerical computation. First, we describe the high accuracy calculation of the MHD equilibrium and then the analysis of the linear MHD instability. The former is the basis of the stability analysis and the latter is closely related to the limiting beta value which is a very important theoretical issue of the tokamak research. To attain a stable tokamak plasma with good confinement property it is necessary to control or suppress disruptive instabilities. We, next, describe the nonlinear MHD instabilities which relate with the disruption phenomena. Lastly, we describe vectorization of the MHD codes. The above MHD codes for fusion plasma analyses are relatively simple though very time-consuming and parts of the codes which need a lot of CPU time concentrate on a small portion of the codes, moreover, the codes are usually used by the developers of the codes themselves, which make it comparatively easy to attain a high performance ratio on the vector processor. (author)

  15. MHD channel performance for potential early commercial MHD power plants

    International Nuclear Information System (INIS)

    Swallom, D.W.

    1981-01-01

    The commercial viability of full and part load early commercial MHD power plants is examined. The load conditions comprise a mass flow of 472 kg/sec in the channel, Rosebud coal, 34% by volume oxygen in the oxidizer preheated to 922 K, and a one percent by mass seeding with K. The full load condition is discussed in terms of a combined cycle plant with optimized electrical output by the MHD channel. Various electrical load parameters, pressure ratios, and magnetic field profiles are considered for a baseload MHD generator, with a finding that a decelerating flow rate yields slightly higher electrical output than a constant flow rate. Nominal and part load conditions are explored, with a reduced gas mass flow rate and an enriched oxygen content. An enthalpy extraction of 24.6% and an isentropic efficiency of 74.2% is predicted for nominal operation of a 526 MWe MHD generator, with higher efficiencies for part load operation

  16. Electromagnetic pulse coupling through an aperture into a two-parallel-plate region

    Science.gov (United States)

    Rahmat-Samii, Y.

    1978-01-01

    Analysis of electromagnetic-pulse (EMP) penetration via apertures into cavities is an important study in designing hardened systems. In this paper, an integral equation procedure is developed for determining the frequency and consequently the time behavior of the field inside a two-parallel-plate region excited through an aperture by an EMP. Some discussion of the numerical results is also included in the paper for completeness.

  17. Test Particle Energization and the Anisotropic Effects of Dynamical MHD Turbulence

    Science.gov (United States)

    González, C. A.; Dmitruk, P.; Mininni, P. D.; Matthaeus, W. H.

    2017-11-01

    In this paper, we analyze the effect of dynamical three-dimensional magnetohydrodynamic (MHD) turbulence on test particle acceleration and compare how this evolving system affects particle energization by current sheet interaction, as opposed to frozen-in-time fields. To do this, we analyze the ensemble particle acceleration for static electromagnetic fields extracted from direct numerical simulations of the MHD equations, and compare it with the dynamical fields. We show that a reduction in particle acceleration in the dynamical model results from particle trapping in field lines, which forces the particles to be advected by the flow and suppresses long exposures to the strong electric field gradients that take place between structures and generate (among other effects) an efficient particle acceleration in the static case. In addition, we analyze the effect of anisotropy caused by the mean magnetic field. It is well known that for sufficiently strong external fields, the system experiences a transition toward a two-dimensional flow. This causes an increment in the size of the coherent structures, resulting in a magnetized state of the particles and a reduction in particle energization.

  18. 3D simulation studies of tokamak plasmas using MHD and extended-MHD models

    International Nuclear Information System (INIS)

    Park, W.; Chang, Z.; Fredrickson, E.; Fu, G.Y.

    1996-01-01

    The M3D (Multi-level 3D) tokamak simulation project aims at the simulation of tokamak plasmas using a multi-level tokamak code package. Several current applications using MHD and Extended-MHD models are presented; high-β disruption studies in reversed shear plasmas using the MHD level MH3D code, ω *i stabilization and nonlinear island saturation of TAE mode using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D ++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree which agree well with experimental data

  19. Preliminary results of MHD stability in HL-1 tokamak

    International Nuclear Information System (INIS)

    Zheng Yongzhen; Ma Tengcai; Xiao Zhenggui Cai Renfang

    1987-01-01

    In this paper, MHD activities of HL-1 tokamak plasma are studied with Fourier transform and correlatio analysis. The poloidal modes m = 1, 2, 3,4 and toroidal modes n of MHD magnetic fluctuation signals are detected. Methods for suppressing MHD instabilities are suggested and tested, after MHD instabilities are studied in HL-1. The effects of MHD characteristics in the beginning stage of discharge on the whole process of discharge are analyzed. The disruption, in HL-1 device could be divided into three kinds: internal disruption, minor disruption and major disruption. The result shows that HL-1 will have a better operation condition if internal disruption appears. In is end, the stable operation region of HL-1 tokamak is also given

  20. Effect of Hartmann layer resolution for MHD flow in a straight ...

    Indian Academy of Sciences (India)

    851–861. c Indian Academy of Sciences. Effect of Hartmann layer resolution for MHD flow in a straight, conducting duct at high Hartmann numbers. SHARANYA SUBRAMANIAN1,∗, P K SWAIN2,. A V DESHPANDE1 and P SATYAMURTHY2. 1Mechanical Engineering Department, Veermata Jijabai Technological Institute,.

  1. MHD Effects of a Ferritic Wall on Tokamak Plasmas

    Science.gov (United States)

    Hughes, Paul E.

    It has been recognized for some time that the very high fluence of fast (14.1MeV) neutrons produced by deuterium-tritium fusion will represent a major materials challenge for the development of next-generation fusion energy projects such as a fusion component test facility and demonstration fusion power reactor. The best-understood and most promising solutions presently available are a family of low-activation steels originally developed for use in fission reactors, but the ferromagnetic properties of these steels represent a danger to plasma confinement through enhancement of magnetohydrodynamic instabilities and increased susceptibility to error fields. At present, experimental research into the effects of ferromagnetic materials on MHD stability in toroidal geometry has been confined to demonstrating that it is still possible to operate an advanced tokamak in the presence of ferromagnetic components. In order to better quantify the effects of ferromagnetic materials on tokamak plasma stability, a new ferritic wall has been installated in the High Beta Tokamak---Extended Pulse (HBT-EP) device. The development, assembly, installation, and testing of this wall as a modular upgrade is described, and the effect of the wall on machine performance is characterized. Comparative studies of plasma dynamics with the ferritic wall close-fitting against similar plasmas with the ferritic wall retracted demonstrate substantial effects on plasma stability. Resonant magnetic perturbations (RMPs) are applied, demonstrating a 50% increase in n = 1 plasma response amplitude when the ferritic wall is near the plasma. Susceptibility of plasmas to disruption events increases by a factor of 2 or more with the ferritic wall inserted, as disruptions are observed earlier with greater frequency. Growth rates of external kink instabilities are observed to be twice as large in the presence of a close-fitting ferritic wall. Initial studies are made of the influence of mode rotation frequency

  2. Damage effect and mechanism of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    Science.gov (United States)

    Xiao-Wen, Xi; Chang-Chun, Chai; Gang, Zhao; Yin-Tang, Yang; Xin-Hai, Yu; Yang, Liu

    2016-04-01

    The damage effect and mechanism of the electromagnetic pulse (EMP) on the GaAs pseudomorphic high electron mobility transistor (PHEMT) are investigated in this paper. By using the device simulation software, the distributions and variations of the electric field, the current density and the temperature are analyzed. The simulation results show that there are three physical effects, i.e., the forward-biased effect of the gate Schottky junction, the avalanche breakdown, and the thermal breakdown of the barrier layer, which influence the device current in the damage process. It is found that the damage position of the device changes with the amplitude of the step voltage pulse. The damage appears under the gate near the drain when the amplitude of the pulse is low, and it also occurs under the gate near the source when the amplitude is sufficiently high, which is consistent with the experimental results. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900), and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  3. Annular MHD Physics for Turbojet Energy Bypass

    Science.gov (United States)

    Schneider, Steven J.

    2011-01-01

    The use of annular Hall type MHD generator/accelerator ducts for turbojet energy bypass is evaluated assuming weakly ionized flows obtained from pulsed nanosecond discharges. The equations for a 1-D, axisymmetric MHD generator/accelerator are derived and numerically integrated to determine the generator/accelerator performance characteristics. The concept offers a shockless means of interacting with high speed inlet flows and potentially offers variable inlet geometry performance without the complexity of moving parts simply by varying the generator loading parameter. The cycle analysis conducted iteratively with a spike inlet and turbojet flying at M = 7 at 30 km altitude is estimated to have a positive thrust per unit mass flow of 185 N-s/kg. The turbojet allowable combustor temperature is set at an aggressive 2200 deg K. The annular MHD Hall generator/accelerator is L = 3 m in length with a B(sub r) = 5 Tesla magnetic field and a conductivity of sigma = 5 mho/m for the generator and sigma= 1.0 mho/m for the accelerator. The calculated isentropic efficiency for the generator is eta(sub sg) = 84 percent at an enthalpy extraction ratio, eta(sub Ng) = 0.63. The calculated isentropic efficiency for the accelerator is eta(sub sa) = 81 percent at an enthalpy addition ratio, eta(sub Na) = 0.62. An assessment of the ionization fraction necessary to achieve a conductivity of sigma = 1.0 mho/m is n(sub e)/n = 1.90 X 10(exp -6), and for sigma = 5.0 mho/m is n(sub e)/n = 9.52 X 10(exp -6).

  4. Steroid hormone regulation of EMP2 expression and localization in the endometrium

    Directory of Open Access Journals (Sweden)

    Williams Carmen J

    2008-04-01

    Full Text Available Abstract Background The tetraspan protein epithelial membrane protein-2 (EMP2, which mediates surface display of diverse proteins, is required for endometrial competence in blastocyst implantation, and is uniquely correlated with poor survival from endometrial adenocarcinoma tumors. Because EMP2 is differentially expressed in the various stages of the murine and human estrous cycle, we tested the hypothesis that the steroid hormones progesterone and estrogen influence EMP2 expression and localization. Methods Frozen human proliferative and secretory endometrium were collected and analyzed for EMP2 expression using SDS-PAGE/Western blot analysis. The response of EMP2 to progesterone and estradiol was determined using a combination of real-time PCR, SDS-PAGE/Western blot analysis, and confocal immunofluorescence in the human endometrial carcinoma cell line RL95-2. To confirm the in vitro results, ovariectomized mice were treated with progesterone or estradiol, and EMP2 expression was analyzed using immunohistochemistry. Results Within normal human endometrium, EMP2 expression is upregulated in the secretory phase relative to the proliferative phase. To understand the role of steroid hormones on EMP2 expression, we utilized RL95-2 cells, which express both estrogen and progesterone receptors. In RL95-2 cells, both estradiol and progesterone induced EMP2 mRNA expression, but only progesterone induced EMP2 protein expression. To compare steroid hormone regulation of EMP2 between humans and mice, we analyzed EMP2 expression in ovarectomized mice. Similar to results observed in humans, progesterone upregulated endometrial EMP2 expression and induced EMP2 translocation to the plasma membrane. Estradiol did not promote translocation to the cell surface, but moderately induced EMP2 expression in cytoplasmic compartments in vivo. Conclusion These findings suggest that targeting of EMP2 to specific locations under the influence of these steroid hormones may

  5. Effect of Magnetic Flux Density and Applied Current on Temperature, Velocity and Entropy Generation Distributions in MHD Pumps

    Directory of Open Access Journals (Sweden)

    M. Kiyasatfar

    2011-01-01

    Full Text Available In the present study, simulation of steady state, incompressible and fully developed laminar flow has been conducted in a magneto hydrodynamic (MHD pump. The governing equations are solved numerically by finite-difference method. The effect of the magnetic flux density and current on the flow and temperature distributions in a MHD pump is investigated. The obtained results showed that controlling the flow and the temperature is possible through the controlling of the applied current and the magnetic flux. Furthermore, the effects of the magnetic flux density and current on entropy generation in MHD pump are considered. Our presented numerical results are in good agreement with the experimental data showed in literature.

  6. Resistive MHD Stability Analysis in Near Real-time

    Science.gov (United States)

    Glasser, Alexander; Kolemen, Egemen

    2017-10-01

    We discuss the feasibility of a near real-time calculation of the tokamak Δ' matrix, which summarizes MHD stability to resistive modes, such as tearing and interchange modes. As the operational phase of ITER approaches, solutions for active feedback tokamak stability control are needed. It has been previously demonstrated that an ideal MHD stability analysis is achievable on a sub- O (1 s) timescale, as is required to control phenomena comparable with the MHD-evolution timescale of ITER. In the present work, we broaden this result to incorporate the effects of resistive MHD modes. Such modes satisfy ideal MHD equations in regions outside narrow resistive layers that form at singular surfaces. We demonstrate that the use of asymptotic expansions at the singular surfaces, as well as the application of state transition matrices, enable a fast, parallelized solution to the singular outer layer boundary value problem, and thereby rapidly compute Δ'. Sponsored by US DOE under DE-SC0015878 and DE-FC02-04ER54698.

  7. Density profile effects on confinement and MHD stability of currentless NBI plasmas in Heliotron E

    International Nuclear Information System (INIS)

    Sudo, Shigeru; Zushi, Hideki; Kondo, Katsumi

    1993-01-01

    Density profile effects on confinement and MHD stability of currentless NBI plasmas in Heliotron E are studied. The peaked density profile produced by pellet injection increases the stored energy by 20-30% compared to the gas puffed plasmas which obey the empirical stellarator/heliotron scaling in a moderate density range. In contrast to confinement, the peaked pressure profile tends to destabilize the plasma. By limiter insertion, MHD instability occurs (seems to locate near ι/2π=1) even in case of low β (β 0 ≤1%, where β 0 is the central β value) plasmas. On the other hand, the mode of m/n=3/2 at ι/2π=2/3, seems to be a key parameter to the major MHD instability in case of high β (β 0 ≥2%) plasmas. (author)

  8. 3D simulation studies of tokamak plasmas using MHD and extended-MHD models

    International Nuclear Information System (INIS)

    Park, W.; Chang, Z.; Fredrickson, E.; Fu, G.Y.; Pomphrey, N.; Sugiyama, L.E.

    1997-01-01

    The M3D (Multi-level 3D) tokamak simulation project aims at the simulation of tokamak plasmas using a multi-level tokamak code package. Several current applications using MHD and Extended-MHD models are presented; high-β disruption studies in reversed shear plasmas using the MHD level MH3D code, ω *i stabilization and nonlinear island rotation studies using the two-fluid level MH3D-T code, studies of nonlinear saturation of TAE modes using the hybrid particle/MHD level MH3D-K code, and unstructured mesh MH3D ++ code studies. In particular, three internal mode disruption mechanisms are identified from simulation results which agree well with experimental data

  9. Nuclear pulse. I - Awakening to the chaos factor

    Science.gov (United States)

    Broad, W. J.

    1981-05-01

    The discovery of the significance of the high-voltage wave termed electromagnetic pulse (EMP), which occurs following the high-altitude detonation of a nuclear device, is discussed. The disruptions to the street lights, burglar alarms and circuit breakers of Hawaii caused by the detonation of a nuclear device 248 mi above Johnson Island in the Pacific in July, 1962 are described and attributed to the Compton electrons produced by the impact of gamma rays from the nuclear explosion on air in the upper atmosphere. It is pointed out, however, that at the time of the explosion, most communications systems were based on vacuum tube and electromechanical technology, which is about 10,000,000 times harder against EMP than integrated solid-state circuitry, and thus the threat posed by EMP to the power grid and communications capabilities was not apparent. Efforts undertaken to harden discrete (missile) and communications systems against EMP are outlined for the example of the Safeguard ABM system, and difficulties are pointed out. Soviet awareness of EMP is considered, and the discovery of vacuum tubes on board the state-of-the-art Foxbat MiG interceptor flown into Japan is noted as a possible indicator of this awareness. It is concluded that the problem of EMP will increase in significance as semiconductor electronics proliferates.

  10. Performa Supply Chain Emping Melinjo di Kabupaten Bantul Daerah Istimewa Yogyakarta

    Directory of Open Access Journals (Sweden)

    Eni Istiyanti

    2017-07-01

    Full Text Available Emping melinjo was one of the agroindustry-products that had great potential to be developed. The industry of emping melinjo contributed more on economic growth in the reason of creating jobs and alleviate poverty. The purpose of this study was to describe the performance of supply chain of emping melinjo from upstream to downstream and analyze the efficiency of supply chain of emping melinjo in Bantul regency. Field study to obtain primary data was done through interviews with the practitioners of emping melinjo supply chain (including farmers and merchants of melinjo as well as producers and retailers of melinjo chips. The results of field studies then tabulated and analyzed descriptively and quantitatively using Linear Programming. The analysis showed that there were 37 supply chain networks of emping melinjo in Bantul. The practitioners of upstream supply chain were melinjo farmers, middlemen, traders, wholesalers, and retailers, while in the downstream, were emping melinjo producers, traders, small traders, wholesalers, retailers and consumers. The activities of the doer of emping melinjo supply chain includes purchasing, sales, harvesting, packaging, packing, stripping, storage, loading and unloading, transporting, sorting and grading. The flow of products and money in the supply chain of emping melinjo run smoothly, while the flow of information was sluggish. Based on linear programming analysis the cost of supply chain of emping melinjo would reach minimum level at Rp33,969,264 per week if the production of emping melinjo as many as 25 361 kg per week wich was distributed using 22 networks.

  11. Absorption of short-pulse electromagnetic energy by a resistively loaded straight wire

    International Nuclear Information System (INIS)

    Miller, E.K.; Deadrick, F.J.; Landt, J.A.

    1975-01-01

    Absorption of short-pulse electromagnetic energy by a resistively loaded straight wire is examined. Energy collected by the wire, load energy, peak load currents, and peak load voltages are found for a wide range of parameters, with particular emphasis on nuclear electromagnetic pulse (EMP) phenomena. A series of time-sequenced plots is used to illustrate pulse propagation on wires when loads and wire ends are encountered

  12. Numerical simulation of narrow bipolar electromagnetic pulses generated by thunderstorm discharges

    Science.gov (United States)

    Bochkov, E. I.; Babich, L. P.; Kutsyk, I. M.

    2013-07-01

    Using the concept of avalanche relativistic runaway electrons (REs), we perform numerical simulations of compact intracloud discharge (CID) as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-VHF range, called narrow bipolar pulses (NBPs). For several values of the field overvoltage and altitude at which the discharge develops, the numbers of seed electrons initiating the avalanche are evaluated, with which the calculated EMP characteristics are consistent with the measured NBP parameters. We note shortcomings in the hypothesis assuming participation of cosmic ray air showers in avalanche initiation. The discharge capable of generating NBPs produces REs in numbers close to those in the source of terrestrial γ-ray flashes (TGFs), which can be an argument in favor of a unified NBP and TGF source.

  13. Numerical simulation of narrow bipolar electromagnetic pulses generated by thunderstorm discharges

    International Nuclear Information System (INIS)

    Bochkov, E. I.; Babich, L. P.; Kutsyk, I. M.

    2013-01-01

    Using the concept of avalanche relativistic runaway electrons (REs), we perform numerical simulations of compact intracloud discharge (CID) as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-VHF range, called narrow bipolar pulses (NBPs). For several values of the field overvoltage and altitude at which the discharge develops, the numbers of seed electrons initiating the avalanche are evaluated, with which the calculated EMP characteristics are consistent with the measured NBP parameters. We note shortcomings in the hypothesis assuming participation of cosmic ray air showers in avalanche initiation. The discharge capable of generating NBPs produces REs in numbers close to those in the source of terrestrial γ-ray flashes (TGFs), which can be an argument in favor of a unified NBP and TGF source

  14. MHD Generating system

    Science.gov (United States)

    Petrick, Michael; Pierson, Edward S.; Schreiner, Felix

    1980-01-01

    According to the present invention, coal combustion gas is the primary working fluid and copper or a copper alloy is the electrodynamic fluid in the MHD generator, thereby eliminating the heat exchangers between the combustor and the liquid-metal MHD working fluids, allowing the use of a conventional coalfired steam bottoming plant, and making the plant simpler, more efficient and cheaper. In operation, the gas and liquid are combined in a mixer and the resulting two-phase mixture enters the MHD generator. The MHD generator acts as a turbine and electric generator in one unit wherein the gas expands, drives the liquid across the magnetic field and thus generates electrical power. The gas and liquid are separated, and the available energy in the gas is recovered before the gas is exhausted to the atmosphere. Where the combustion gas contains sulfur, oxygen is bubbled through a side loop to remove sulfur therefrom as a concentrated stream of sulfur dioxide. The combustor is operated substoichiometrically to control the oxide level in the copper.

  15. Study of MHD problems in liquid metal blankets of fusion reactors

    International Nuclear Information System (INIS)

    Michael, I.

    1984-12-01

    This study describes in a concise form the state of knowledge regarding MHD problems to be expected in case of use of liquid metal in the blankets of fusion reactors with magnetic confinement. MHD pressure losses and MHD friction coefficients in the straight channel, in bent sections and in case of variation of the channel cross section play a major role because the high MHD flow resistances call for high pumping powers. Influencing the velocity profile transverse to the main flow direction of the liquid metal by application of an external, strong magnetic field bears consequences on the release and transport of corrosion products in the liquid metal circuit and on the heat transfer. Possibilities of reducing the MHD effects are discussed. However, it becomes obvious that an account of the lack of experimental results there are still major gaps in the knowledge of MHD effects occurring in strong magnetic fields. These gaps can be greatly reduced by implementation of an experimental program as proposed in this report. (orig.) [de

  16. Investigations on high speed MHD liquid flow

    International Nuclear Information System (INIS)

    Yamasaki, Takasuke; Kamiyama, Shin-ichi.

    1982-01-01

    Lately, the pressure drop problem of MHD two-phase flow in a duct has been investigated theoretically and experimentally in conjunction with the problems of liquid metal MHD two-phase flow power-generating cycle or of liquid metal boiling two-phase flow in the blanket of a nuclear fusion reactor. Though many research results have been reported so far for MHD single-phase flow, the hydrodynamic studies on high speed two-phase flow are reported only rarely, specifically the study dealing with the generation of cavitation is not found. In the present investigation, the basic equation was derived, analyzing the high speed MHD liquid flow in a diverging duct as the one-dimensional flow of homogeneous two-phase fluid of small void ratio. Furthermore, the theoretical solution for the effect of magnetic field on cavitation-generating conditions was tried. The pressure distribution in MHD flow in a duct largely varies with load factor, and even if the void ratio is small, the pressure distribution in two-phase flow is considerably different from that in single-phase flow. Even if the MHD two-phase flow in a duct is subsonic flow at the throat, the critical conditions may be achieved sometimes in a diverging duct. It was shown that cavitation is more likely to occur as magnetic field becomes more intense if it is generated downstream of the throat. This explains the experimental results qualitatively. (Wakatsuki, Y.)

  17. Effects of couple stresses in MHD channel flow

    International Nuclear Information System (INIS)

    Soundalgekar, V.M.; Aranake, R.N.

    1977-01-01

    An analysis of fully developed MHD channel flow of an electrically conducting incompressible fluid, taking into account the couple stresses, is carried out. Exact solutions are derived for velocity profiles, current density, skin-friction and coefficient of mass flux. They are influenced by the magnetic field, the loading parameter k, and the non-dimensional parameter (a=b 1 /lambda). Their variations with respect to M, k and a are represented graphically, this is followed by a physical discussion. It is observed that the couple stresses are more effective in the presence of a very weak magnetic field. (Auth.)

  18. Report of commission for investigating MHD on a visit to U.S. Part 2. Report on each place of visit; Hobei MHD chosadan hokokusho. 2. Homonsakibetsu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-01-01

    The members of MHD project examination subcommittee made an investigative tour of the U.S. on the state of development of MHD generation. This report of the 2nd part explains opinions and the present status of the R and D on MHD generation by each of the 19 institutions visited. The U.S. research on MHD generation is under the leadership of DOE, whereby the budget for the development is so large as nearly one hundred million dollars have been provided for several years. The purpose is the effective use of domestic coal. General Electric is of the opinion that a combined gas turbine system will be put to practical use earlier because MHD takes time for practicability despite its highest efficiency in coal-utilized power generation. Yet, GE thinks MHD will be more attractive in the future. Reynolds Metal is considering application of MHD generation to the electro-chemical industry at present. According to Reynolds, combined supply of electric output and heat of MHD can reduce the use of calorie per ton of aluminum from 240 MBTU to 100. Montana Power is promoting practicability through a combined plan with DOE-built MHD generation. (NEDO)

  19. Studies of exposure of rabbits to electromagnetic pulsed fields

    International Nuclear Information System (INIS)

    Cleary, S.F.; Nickless, F.; Liu, L.M.; Hoffman, R.

    1980-01-01

    Dutch rabbits were acutely exposed to electromagnetic pulsed (EMP) fields (pulse duration 0.4 mus, field strengths of 1--2 kV/cm and pulse repetition rates in the range of 10 to 38 Hz) for periods of up to two hours. The dependent variables investigated were pentobarbital-induced sleeping time and serum chemistry (including serum triglycerides, creatine phosphokinase (CPK) isoenzymes, and sodium and potassium). Core temperature measured immediately pre-exposure and postexposure revealed no exposure-related alterations. Over the range of field strengths and pulse durations investigated no consistent, statistically significant alterations were found in the end-points investigated

  20. Decay of MHD-scale Kelvin-Helmholtz vortices mediated by parasitic electron dynamics

    International Nuclear Information System (INIS)

    Nakamura, T.K.M.; Hayashi, D.; Fujimoto, M.; Shinohara, I.

    2004-01-01

    We have simulated nonlinear development of MHD-scale Kelvin-Helmholtz (KH) vortices by a two-dimensional two-fluid system including finite electron inertial effects. In the presence of moderate density jump across a shear layer, in striking contrast to MHD results, MHD KH vortices are found to decay by the time one eddy turnover is completed. The decay is mediated by smaller vortices that appear within the parent vortex and stays effective even when the shear layer width is made larger. It is shown that the smaller vortices are basically of MHD nature while the seeding for these is achieved by the electron inertial effect. Application of the results to the magnetotail boundary layer is discussed

  1. MHD PbLi experiments in MaPLE loop at UCLA

    International Nuclear Information System (INIS)

    Courtessole, C.; Smolentsev, S.; Sketchley, T.; Abdou, M.

    2016-01-01

    Highlights: • The paper overviews the MaPLE facility at UCLA: one-of-a-few PbLi MHD loop in the world. • We present the progress achieved in development and testing of high-temperature PbLi flow diagnostics. • The most important MHD experiments carried out since the first loop operation in 2011 are summarized. - Abstract: Experiments on magnetohydrodynamic (MHD) flows are critical to understanding complex flow phenomena in ducts of liquid metal blankets, in particular those that utilize eutectic alloy lead–lithium as breeder/coolant, such as self-cooled, dual-coolant and helium-cooled lead–lithium blanket concepts. The primary goal of MHD experiments at UCLA using the liquid metal flow facility called MaPLE (Magnetohydrodynamic PbLi Experiment) is to address important MHD effects, heat transfer and flow materials interactions in blanket-relevant conditions. The paper overviews the one-of-a-kind MaPLE loop at UCLA and presents recent experimental activities, including the development and testing of high-temperature PbLi flow diagnostics and experiments that have been performed since the first loop operation in 2011. We also discuss MaPLE upgrades, which need to be done to substantially expand the experimental capabilities towards a new class of MHD flow phenomena that includes buoyancy effects.

  2. MHD PbLi experiments in MaPLE loop at UCLA

    Energy Technology Data Exchange (ETDEWEB)

    Courtessole, C., E-mail: cyril@fusion.ucla.edu; Smolentsev, S.; Sketchley, T.; Abdou, M.

    2016-11-01

    Highlights: • The paper overviews the MaPLE facility at UCLA: one-of-a-few PbLi MHD loop in the world. • We present the progress achieved in development and testing of high-temperature PbLi flow diagnostics. • The most important MHD experiments carried out since the first loop operation in 2011 are summarized. - Abstract: Experiments on magnetohydrodynamic (MHD) flows are critical to understanding complex flow phenomena in ducts of liquid metal blankets, in particular those that utilize eutectic alloy lead–lithium as breeder/coolant, such as self-cooled, dual-coolant and helium-cooled lead–lithium blanket concepts. The primary goal of MHD experiments at UCLA using the liquid metal flow facility called MaPLE (Magnetohydrodynamic PbLi Experiment) is to address important MHD effects, heat transfer and flow materials interactions in blanket-relevant conditions. The paper overviews the one-of-a-kind MaPLE loop at UCLA and presents recent experimental activities, including the development and testing of high-temperature PbLi flow diagnostics and experiments that have been performed since the first loop operation in 2011. We also discuss MaPLE upgrades, which need to be done to substantially expand the experimental capabilities towards a new class of MHD flow phenomena that includes buoyancy effects.

  3. A performance analysis for MHD power cycles operating at maximum power density

    International Nuclear Information System (INIS)

    Sahin, Bahri; Kodal, Ali; Yavuz, Hasbi

    1996-01-01

    An analysis of the thermal efficiency of a magnetohydrodynamic (MHD) power cycle at maximum power density for a constant velocity type MHD generator has been carried out. The irreversibilities at the compressor and the MHD generator are taken into account. The results obtained from power density analysis were compared with those of maximum power analysis. It is shown that by using the power density criteria the MHD cycle efficiency can be increased effectively. (author)

  4. Outline of fiscal 1970 achievements in research on MHD power generation; 1970 nendo MHD hatsuden kenkyu seika gaiyo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1970-07-01

    Compiled are the results of studies conducted in fiscal 1970 on MHD (magnetohydrodynamic) power generation. In the operation test and modification of the 1000kW-class MHD power generator, modification is carried out involving the combustion system, seed collecting method, and power generation channel, and reviews through experiments are conducted about the analysis and control of the boundary layer structure. In the operation test of the MHD power generator designed for prolonged operation, a test operation for resistance to heat and seeds continues more than 100 hours using a cold wall type power generation channel constituted of water cooled ceramics, and the ceramics are analyzed for failure and loss. Studies are also conducted involving MHD power generator heat exchangers, seed collecting methods, electrode materials for MHD power generators, heat-resistant materials for MHD power generators, thermal performance rating for MHD power plants, etc. In the research and development of superconductive electromagnets, superconductive electromagnets are developed and tested for 1000kW-class MHD power generators, and studies are conducted on turbine type helium liquefiers, superinsulated superconductive electromagnetic field generators, etc. (NEDO)

  5. MHD Modeling of Conductors at Ultra-High Current Density

    International Nuclear Information System (INIS)

    ROSENTHAL, STEPHEN E.; DESJARLAIS, MICHAEL P.; SPIELMAN, RICK B.; STYGAR, WILLIAM A.; ASAY, JAMES R.; DOUGLAS, M.R.; HALL, C.A.; FRESE, M.H.; MORSE, R.L.; REISMAN, D.B.

    2000-01-01

    In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator, the authors have revisited a problem first described in detail by Heinz Knoepfel. Unlike the 1-Tesla MITLs of pulsed power accelerators used to produce intense particle beams, Z's disc transmission line (downstream of the current addition) is in a 100--1,200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 they have been investigating the conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are (1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into the MHD computations. Certain features are strongly dependent on the details of the conductivity model

  6. MHD Modeling of Conductors at Ultra-High Current Density

    International Nuclear Information System (INIS)

    Rosenthal, S.E.; Asay, J.R.; Desjarlais, M.P.; Douglas, M.R.; Frese, M.H.; Hall, C.A.; Morse, R.L.; Reisman, D.; Spielman, R.B.; Stygar, W.A.

    1999-01-01

    In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator we have revisited a problem first described in detail by Heinz Knoepfel. MITLs of previous pulsed power accelerators have been in the 1-Tesla regime. Z's disc transmission line (downstream of the current addition) is in a 100-1200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 we have been investigating conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are ( 1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into our MHD computations. Certain features are strongly dependent on the details of the conductivity model. Comparison with measurements on Z will be discussed

  7. Performance and flow characteristics of MHD seawater thruster

    Energy Technology Data Exchange (ETDEWEB)

    Doss, E.D.

    1990-01-01

    The main goal of the research is to investigate the effects of strong magnetic fields on the electrical and flow fields inside MHD thrusters. The results of this study is important in the assessment of the feasibility of MHD seawater propulsion for the Navy. To accomplish this goal a three-dimensional fluid flow computer model has been developed and applied to study the concept of MHD seawater propulsion. The effects of strong magnetic fields on the current and electric fields inside the MHD thruster and their interaction with the flow fields, particularly those in the boundary layers, have been investigated. The results of the three-dimensional computations indicate that the velocity profiles are flatter over the sidewalls of the thruster walls in comparison to the velocity profiles over the electrode walls. These nonuniformities in the flow fields give rise to nonuniform distribution of the skin friction along the walls of the thrusters, where higher values are predicted over the sidewalls relative to those over the electrode walls. Also, a parametric study has been performed using the three-dimensional MHD flow model to analyze the performance of continuous electrode seawater thrusters under different operating parameters. The effects of these parameters on the fluid flow characteristics, and on the thruster efficiency have been investigated. Those parameters include the magnetic field (10--20 T), thruster diameter, surface roughness, flow velocity, and the electric load factor. The results show also that the thruster performance improves with the strength of the magnetic field and thruster diameter, and the efficiency decreases with the flow velocity and surface roughness.

  8. A kinetic-MHD model for low frequency phenomena

    International Nuclear Information System (INIS)

    Cheng, C.Z.

    1991-07-01

    A hybrid kinetic-MHD model for describing low-frequency phenomena in high beta anisotropic plasmas that consist of two components: a low energy core component and an energetic component with low density. The kinetic-MHD model treats the low energy core component by magnetohydrodynamic (MHD) description, the energetic component by kinetic approach such as the gyrokinetic equation, and the coupling between the dynamics of these two components through plasma pressure in the momentum equation. The kinetic-MHD model optimizes both the physics contents and the theoretical efforts in studying low frequency MHD waves and transport phenomena in general magnetic field geometries, and can be easily modified to include the core plasma kinetic effects if necessary. It is applicable to any magnetized collisionless plasma system where the parallel electric field effects are negligibly small. In the linearized limit two coupled eigenmode equations for describing the coupling between the transverse Alfven type and the compressional Alfven type waves are derived. The eigenmode equations are identical to those derived from the full gyrokinetic equation in the low frequency limit and were previously analyzed both analytically nd numerically to obtain the eigenmode structure of the drift mirror instability which explains successfully the multi-satellite observation of antisymmetric field-aligned structure of the compressional magnetic field of Pc 5 waves in the magnetospheric ring current plasma. Finally, a quadratic form is derived to demonstrate the stability of the low-frequency transverse and compressional Alfven type instabilities in terms of the pressure anisotropy parameter τ and the magnetic field curvature-pressure gradient parameter. A procedure for determining the stability of a marginally stable MHD wave due to wave-particle resonances is also presented

  9. Effects of couple stresses on MHD Couette flow

    International Nuclear Information System (INIS)

    Soundalgekar, V.M.; Aranake, R.N.

    1978-01-01

    An exact analysis of the effects of the couple stresses on the MHD Couette flow of an electrically conducting, viscous incompressible fluid is carried out. Closed form solutions are derived for the velocity, the current density, the skin-friction at the lower plate, the force to move the upper plate, and the coefficient of mass flux for (i) A→infinity, and (ii) 2M/A 1, where a is the couple stress parameter and M is the Hartmann number. These are shown graphically followed by a discussion. During the course of discussion the effects of A are quantitatively compared with those in the ordinary case. It is observed that in the presence of a magnetic field the skin friction is affected by the couple stresses. (Auth.)

  10. High pressure gas driven liquid metal MHD homopolar generator

    International Nuclear Information System (INIS)

    Itoh, Yasuyuki

    1988-01-01

    A liquid metal MHD homopolar generator is proposed to be used as a high repetition rate pulsed power supply. In the generator, the thermal energy stored in a high pressure gas (He) reservoir is rapidly converted into kinetic energy of a rotating liquid metal (NaK) cylinder which is contracted by a gas driven annular free piston. The rotational kinetic energy is converted into electrical energy by making use of the homopolar generator principle. The conversion efficiency is calculated to be 47% in generating electrical energy of 20 kJ/pulse (1.7 MW peak power) at a repetition rate of 7 Hz. From the viewpoint of energy storage, the high pressure gas reservoir with a charging pressure of 15 MPa is considered to ''electrically'' store the energy at a density of 10 MJ/m 3 . (author)

  11. Multi probes measurements at the PALS Facility Research Centre during high intense laser pulse interactions with various target materials

    Directory of Open Access Journals (Sweden)

    De Marco Massimo

    2018-01-01

    Full Text Available During the interaction of high intense laser pulse with solid target, a large amount of hot electrons is produced and a giant Electromagnetic Pulse (EMP is generated due to the current flowing into the system target–target holder, as well as due to the escaping charged particles in vacuum. EMP production for different target materials is investigated inside and outside the target chamber, using monopole antenna, super wide-band microstrip antenna and Moebius antenna. The EMP consists in a fast transient magnetic field lasting hundreds of nanosecond with frequencies ranging from MHz to tens of GHz. Measurements of magnetic field and return target current in the range of kA were carried out by an inductive target probe (Cikhardt J. et al. Rev. Sci. Instrum. 85 (2014 103507.

  12. MHD stability analyses of a tokamak plasma by time-dependent codes

    International Nuclear Information System (INIS)

    Kurita, Gen-ichi

    1982-07-01

    The MHD properties of a tokamak plasma are investigated by using time evolutional codes. As for the ideal MHD modes we have analyzed the external modes including the positional instability. Linear and nonlinear ideal MHD codes have been developed. Effects of the toroidicity and conducting shell on the external kink mode are studied minutely by the linear code. A new rezoning algorithm is devised and it is successfully applied to express numerically the axisymmetric plasma perturbation in a cylindrical geometry. As for the resistive MHD modes we have developed nonlinear codes on the basis of the reduced set of the resistive MHD equations. By using the codes we have studied the major disruption processes and properties of the low n resistive modes. We have found that the effects of toroidicity and finite poloidal beta are very important. Considering the above conclusion we propose a new scenario of the initiation of the major disruption. (author)

  13. RFX: New tools for real-time MHD control

    International Nuclear Information System (INIS)

    Gnesotto, F.; Luchetta, A.; Marchiori, G.

    2005-01-01

    RFX has been recently modified to improve its capability of controlling different MHD phenomena by means of fast, feedback controlled amplifiers and distributed radial field inductors. The paper, after summarizing the principal results obtained in the past by means of active control of magnetic fields in RFX, describes the recent modifications to the machine and the improvements to the power supplies and to the magnetic diagnostics. The old thick shell has been replaced by a much thinner shell, whose electromagnetic time constants are much shorter than pulse duration, and a system of 192 radial field coils has been added, covering the whole torus surface. Then the paper describes the models used to design the new real-time control system of RFX and gives some preliminary results obtained, with the same techniques, on the EXTRAP-T2R device. The basic choices about the technologies adopted for the new RFX control system are discussed with reference to the general problem of real-time control of MHD instabilities in magnetic fusion devices. Finally, the paper defines the main objectives of the RFX scientific programme aimed at exploiting these new tools. (author)

  14. MHD equilibrium of heliotron J plasmas

    International Nuclear Information System (INIS)

    Suzuki, Yasuhiro; Nakamura, Yuji; Kondo, Katsumi; Nakajima, Noriyoshi; Hayashi, Takaya

    2004-01-01

    MHD equilibria of Heliotron J plasma are investigated by using HINT code. By assuming some profiles of the current density, effects of the net toroidal currents on the magnetohydrodynamics (MHD) equilibrium are investigated. If the rotational transform can be controlled by the currents, the generation of good flux surfaces is expected. In order to study equilibria with self-consistent bootstrap current, the boozer coordinates are constructed by converged HINT equilibrium as a preliminary study. Obtained spectra are compared with ones of VMEC code and both results are consistent. (author)

  15. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments

    National Research Council Canada - National Science Library

    Wilson, Clay

    2006-01-01

    Electromagnetic Pulse (EMP) is an instantaneous, intense energy field that can disrupt at a distance numerous electrical systems and high technology microcircuits that are especially sensitive to power surges...

  16. MHD program plan, FY 1991

    Science.gov (United States)

    1990-10-01

    The current magnetohydrodynamic MHD program being implemented is a result of a consensus established in public meetings held by the Department of Energy in 1984. The public meetings were followed by the formulation of a June 1984 Coal-Fired MHD Preliminary Transition and Program Plan. This plan focused on demonstrating the proof-of-concept (POC) of coal-fired MHD electric power plants by the early 1990s. MHD test data indicate that while there are no fundamental technical barriers impeding the development of MHD power plants, technical risk remains. To reduce the technical risk three key subsystems (topping cycle, bottoming cycle, and seed regeneration) are being assembled and tested separately. The program does not require fabrication of a complete superconducting magnet, but rather the development and testing of superconductor cables. The topping cycle system test objectives can be achieved using a conventional iron core magnet system already in place at a DOE facility. Systems engineering-derived requirements and analytical modeling to support scale-up and component design guide the program. In response to environmental, economic, engineering, and utility acceptance requirements, design choices and operating modes are tested and refined to provide technical specifications for meeting commercial criteria. These engineering activities are supported by comprehensive and continuing systems analyses to establish realistic technical requirements and cost data. Essential elements of the current program are to: develop technical and environmental data for the integrated MHD topping cycle and bottoming cycle systems through POC testing (1000 and 4000 hours, respectively); design, construct, and operate a POC seed regeneration system capable of processing spent seed materials from the MHD bottoming cycle; prepare conceptual designs for a site specific MHD retrofit plant; and continue supporting research necessary for system testing.

  17. Electricity from MHD, 1968. Vol. IV. Open-Cycle MHD. Proceedings of a Symposium on Magnetohydrodynamic Electrical Power Generation

    International Nuclear Information System (INIS)

    1968-01-01

    Proceedings of a Symposium on Magnetohydrodynamic Electrical Power Generation held by the IAEA at Warsaw, 24-30 July 1968. The meeting was attended by some 300 participants from 21 countries and three international organizations. In contrast to the Symposium held two years ago, much more emphasis was placed on the economic aspects of using MHD generators in large-scale power generation. Among closed- cycle systems, the prospects of linking an ultra-high-temperature reactor with an MHD generator were explored, and the advantages gained by having a liquid-metal generator as a 'topper' in a conventional steam generating plant were presented. Comments were made about the disproportionate effect of end and boundary conditions in experimental MHD generators on the main plasma parameters, and estimates were made of the interrelationship to be expected in real generators. The estimates will have to await confirmation until results are obtained on large-scale prototype MHD systems. Progress in materials research, in design and construction of auxiliary equipment such as heat exchangers, supercooled magnets (which are- now commercially available), etc., is accompanied by sophisticated ideas of plant design. The Proceedings are complemented by three Round Table Discussions in which chosen experts from various countries discuss the outlook for closed-cycle gas, closed-cycle liquid-metal and open-cycle MHD, and give their views as to the most fruitful course to follow to achieve economic full-scale power generation. Contents: (Vol. I) 1. Closed-Cycle MHD with Gaseous Working Fluids: (a) Diagnostics (3 papers); (b) Steady-state non-equilibrium ionization (8 papers); (c) Transient non-equilibrium ionization (7 papers); (d) Pre-ionization and gas discharge (4 papers); (e) Fields and flow in MHD channels (10 papers); (0 Instabilities (8 papers); (g) Generator design and performance studies (6 papers); (Vol. II) (h) Shock waves (6 papers); (i) Power generation experiments (13 papers

  18. Astrophysics days and MHD

    International Nuclear Information System (INIS)

    Falgarone, Edith; Rieutord, Michel; Richard, Denis; Zahn, Jean-Paul; Dauchot, Olivier; Daviaud, Francois; Dubrulle, Berengere; Laval, Jean-Philippe; Noullez, Alain; Bourgoin, Mickael; Odier, Philippe; Pinton, Jean-Francois; Leveque, Emmanuel; Chainais, Pierre; Abry, Patrice; Mordant, Nicolas; Michel, Olivier; Marie, Louis; Chiffaudel, Arnaud; Daviaud, Francois; Petrelis, Francois; Fauve, Stephan; Nore, C.; Brachet, M.-E.; Politano, H.; Pouquet, A.; Leorat, Jacques; Grapin, Roland; Brun, Sacha; Delour, Jean; Arneodo, Alain; Muzy, Jean-Francois; Magnaudet, Jacques; Braza, Marianna; Boree, Jacques; Maurel, S.; Ben, L.; Moreau, J.; Bazile, R.; Charnay, G.; Lewandowski, Roger; Laveder, Dimitri; Bouchet, Freddy; Sommeria, Joel; Le Gal, P.; Eloy, C.; Le Dizes, S.; Schneider, Kai; Farge, Marie; Bottausci, Frederic; Petitjeans, Philippe; Maurel, Agnes; Carlier, Johan; Anselmet, Fabien

    2001-05-01

    This publication gathers extended summaries of presentations proposed during two days on astrophysics and magnetohydrodynamics (MHD). The first session addressed astrophysics and MHD: The cold interstellar medium, a low ionized turbulent plasma; Turbulent convection in stars; Turbulence in differential rotation; Protoplanetary disks and washing machines; gravitational instability and large structures; MHD turbulence in the sodium von Karman flow; Numerical study of the dynamo effect in the Taylor-Green eddy geometry; Solar turbulent convection under the influence of rotation and of the magnetic field. The second session addressed the description of turbulence: Should we give up cascade models to describe the spatial complexity of the velocity field in a developed turbulence?; What do we learn with RDT about the turbulence at the vicinity of a plane surface?; Qualitative explanation of intermittency; Reduced model of Navier-Stokes equations: quickly extinguished energy cascade; Some mathematical properties of turbulent closure models. The third session addressed turbulence and coherent structures: Alfven wave filamentation and formation of coherent structures in dispersive MHD; Statistical mechanics for quasi-geo-strophic turbulence: applications to Jupiter's coherent structures; Elliptic instabilities; Physics and modelling of turbulent detached unsteady flows in aerodynamics and fluid-structure interaction; Intermittency and coherent structures in a washing machine: a wavelet analysis of joint pressure/velocity measurements; CVS filtering of 3D turbulent mixing layer using orthogonal wavelets. The last session addressed experimental methods: Lagrangian velocity measurements; Energy dissipation and instabilities within a locally stretched vortex; Study by laser imagery of the generation and breakage of a compressed eddy flow; Study of coherent structures of turbulent boundary layer at high Reynolds number

  19. Advanced energy utilization MHD power generation

    International Nuclear Information System (INIS)

    2008-01-01

    The 'Technical Committee on Advanced Energy Utilization MHD Power Generation' was started to establish advanced energy utilization technologies in Japan, and has been working for three years from June 2004 to May 2007. This committee investigated closed cycle MHD, open cycle MHD, and liquid metal MHD power generation as high-efficiency power generation systems on the earth. Then, aero-space application and deep space exploration technologies were investigated as applications of MHD technology. The spin-off from research and development on MHD power generation such as acceleration and deceleration of supersonic flows was expected to solve unstart phenomena in scramjet engine and also to solve abnormal heating of aircrafts by shock wave. In addition, this committee investigated researches on fuel cells, on secondary batteries, on connection of wind power system to power grid, and on direct energy conversion system from nuclear fusion reactor for future. The present technical report described results of investigations by the committee. (author)

  20. Ceramics and M.H.D

    International Nuclear Information System (INIS)

    Yvars, M.

    1979-10-01

    The materials considered for the insulating walls of a M.H.D. converter are Al 2 O 3 , and the calcium or strontium zirconates. For the conducting walls electricity conducting oxides are being considered such as ZrO 2 or CrO 3 La essentially. The principle of M.H.D. systems is recalled, the materials considered are described as is their behaviour in the corrosive atmospheres of M.H.D. streams [fr

  1. Interface Control Document for the EMPACT Module that Estimates Electric Power Transmission System Response to EMP-Caused Damage

    Energy Technology Data Exchange (ETDEWEB)

    Werley, Kenneth Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mccown, Andrew William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)ory

    2016-06-26

    The EPREP code is designed to evaluate the effects of an Electro-Magnetic Pulse (EMP) on the electric power transmission system. The EPREP code embodies an umbrella framework that allows a user to set up analysis conditions and to examine analysis results. The code links to three major physics/engineering modules. The first module describes the EM wave in space and time. The second module evaluates the damage caused by the wave on specific electric power (EP) transmission system components. The third module evaluates the consequence of the damaged network on its (reduced) ability to provide electric power to meet demand. This third module is the focus of the present paper. The EMPACT code serves as the third module. The EMPACT name denotes EMP effects on Alternating Current Transmission systems. The EMPACT algorithms compute electric power transmission network flow solutions under severely damaged network conditions. Initial solutions are often characterized by unacceptible network conditions including line overloads and bad voltages. The EMPACT code contains algorithms to adjust optimally network parameters to eliminate network problems while minimizing outages. System adjustments include automatically adjusting control equipment (generator V control, variable transformers, and variable shunts), as well as non-automatic control of generator power settings and minimal load shedding. The goal is to evaluate the minimal loss of customer load under equilibrium (steady-state) conditions during peak demand.

  2. MHD turbulent dynamo in astrophysics: Theory and numerical simulation

    Science.gov (United States)

    Chou, Hongsong

    2001-10-01

    This thesis treats the physics of dynamo effects through theoretical modeling of magnetohydrodynamic (MHD) systems and direct numerical simulations of MHD turbulence. After a brief introduction to astrophysical dynamo research in Chapter 1, the following issues in developing dynamic models of dynamo theory are addressed: In Chapter 2, nonlinearity that arises from the back reaction of magnetic field on velocity field is considered in a new model for the dynamo α-effect. The dependence of α-coefficient on magnetic Reynolds number, kinetic Reynolds number, magnetic Prandtl number and statistical properties of MHD turbulence is studied. In Chapter 3, the time-dependence of magnetic helicity dynamics and its influence on dynamo effects are studied with a theoretical model and 3D direct numerical simulations. The applicability of and the connection between different dynamo models are also discussed. In Chapter 4, processes of magnetic field amplification by turbulence are numerically simulated with a 3D Fourier spectral method. The initial seed magnetic field can be a large-scale field, a small-scale magnetic impulse, and a combination of these two. Other issues, such as dynamo processes due to helical Alfvénic waves and the implication and validity of the Zeldovich relation, are also addressed in Appendix B and Chapters 4 & 5, respectively. Main conclusions and future work are presented in Chapter 5. Applications of these studies are intended for astrophysical magnetic field generation through turbulent dynamo processes, especially when nonlinearity plays central role. In studying the physics of MHD turbulent dynamo processes, the following tools are developed: (1)A double Fourier transform in both space and time for the linearized MHD equations (Chapter 2 and Appendices A & B). (2)A Fourier spectral numerical method for direct simulation of 3D incompressible MHD equations (Appendix C).

  3. MHD Ballooning Instability in the Plasma Sheet

    International Nuclear Information System (INIS)

    Cheng, C.Z.; Zaharia, S.

    2003-01-01

    Based on the ideal-MHD model the stability of ballooning modes is investigated by employing realistic 3D magnetospheric equilibria, in particular for the substorm growth phase. Previous MHD ballooning stability calculations making use of approximations on the plasma compressibility can give rise to erroneous conclusions. Our results show that without making approximations on the plasma compressibility the MHD ballooning modes are unstable for the entire plasma sheet where beta (sub)eq is greater than or equal to 1, and the most unstable modes are located in the strong cross-tail current sheet region in the near-Earth plasma sheet, which maps to the initial brightening location of the breakup arc in the ionosphere. However, the MHD beq threshold is too low in comparison with observations by AMPTE/CCE at X = -(8 - 9)R(sub)E, which show that a low-frequency instability is excited only when beq increases over 50. The difficulty is mitigated by considering the kinetic effects of ion gyrorad ii and trapped electron dynamics, which can greatly increase the stabilizing effects of field line tension and thus enhance the beta(sub)eq threshold [Cheng and Lui, 1998]. The consequence is to reduce the equatorial region of the unstable ballooning modes to the strong cross-tail current sheet region where the free energy associated with the plasma pressure gradient and magnetic field curvature is maximum

  4. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments

    National Research Council Canada - National Science Library

    Wilson, Clay

    2008-01-01

    Electromagnetic Pulse (EMP) is an instantaneous, intense energy field that can overload or disrupt at a distance numerous electrical systems and high technology microcircuits, which are especially sensitive to power surges...

  5. Route analysis for MHD equilibria

    International Nuclear Information System (INIS)

    Kikuchi, Fumio; Aizawa, Tatsuhiko

    1982-01-01

    In Tokamak facilities which are promising in nuclear fusion reactor development, the plasma in the core is often described by MHD approximation. Specifically, since an axisymmetric torus is approximately assumed as the first wall (shell) shape in actual Tokamak facilities, the Grad-Shafranov equation to be satisfied by an axisymmetric equilibrium solution for ideal MHD fluid must be solved, and the characteristics of its solution must be clarified. This paper shows the outline of the numerical calculation which employs both the incremental method taking the particular incremental nodal point values as the control parameters and the interaction method in accordance with Newton method at the same time, the analysis objective being a non-linear eigenvalue problem dealing the boundary of plasma region with surrounding vacuum region as the free boundary. Next, the detailed route analysis of the equilibrium solution is performed, utilizing the above numerical calculation technique, to clarify the effect of shell shape on the behaviour of the equilibrium solution. As the shape of the shell, a rectangular section torus, which have a notch depression at a part of the shell inner boundary, is considered. In the paper, the fundamental MHD equation and its approximate solution by the finite element method, the behaviour of plasma equilibrium solution in a shell having a notch, and the effect of notch shapes on plasma behaviour are described. This analysis verifies the effectiveness of the calculation method. (Wakatsuki, Y.)

  6. Effect of Trapped Energetic Ions on MHD Activity in Spherical Tori

    International Nuclear Information System (INIS)

    White, R.B.; Kolesnichenko, Ya.I.; Lutsenko, V.V.; Marchenko, V.S.

    2002-01-01

    It is shown that the increase of beta (the ratio of plasma pressure to the magnetic field pressure) may change the character of the influence of trapped energetic ions on MHD stability in spherical tori. Namely, the energetic ions, which stabilize MHD modes (such as the ideal-kink mode, collisionless tearing mode, and semi-collisional tearing mode) at low beta, have a destabilizing influence at high beta unless the radial distribution of the energetic ions is very peaked

  7. MHD instabilities in heliotron/torsatron

    International Nuclear Information System (INIS)

    Wakatani, Masahiro; Nakamura, Yuji; Ichiguchi, Katsuji

    1992-01-01

    Recent theoretical results on MHD instabilities in heliotron/torsatron are reviewed. By comparing the results with experimental data in Heliotron E, Heliotron DR and ATF, it is pointed out that resistive interchange modes are the most crucial instabilities, since the magnetic hill occupies a substantial region of the plasma column. Development of three-dimensional MHD equilibrium codes has made significant progress. By applying the local stability criteria shown by D 1 (ideal MHD mode) and D R (resistive MHD mode) to the equilibria given by the three-dimensional codes such as BETA and VMEC, stability thresholds for the low n ideal modes or the low n resistive modes may be estimated with resonable accuracy, where n is a toroidal mode number. (orig.)

  8. Newtonian CAFE: a new ideal MHD code to study the solar atmosphere

    Science.gov (United States)

    González-Avilés, J. J.; Cruz-Osorio, A.; Lora-Clavijo, F. D.; Guzmán, F. S.

    2015-12-01

    We present a new code designed to solve the equations of classical ideal magnetohydrodynamics (MHD) in three dimensions, submitted to a constant gravitational field. The purpose of the code centres on the analysis of solar phenomena within the photosphere-corona region. We present 1D and 2D standard tests to demonstrate the quality of the numerical results obtained with our code. As solar tests we present the transverse oscillations of Alfvénic pulses in coronal loops using a 2.5D model, and as 3D tests we present the propagation of impulsively generated MHD-gravity waves and vortices in the solar atmosphere. The code is based on high-resolution shock-capturing methods, uses the Harten-Lax-van Leer-Einfeldt (HLLE) flux formula combined with Minmod, MC, and WENO5 reconstructors. The divergence free magnetic field constraint is controlled using the Flux Constrained Transport method.

  9. Linear ideal MHD stability calculations for ITER

    International Nuclear Information System (INIS)

    Hogan, J.T.

    1988-01-01

    A survey of MHD stability limits has been made to address issues arising from the MHD--poloidal field design task of the US ITER project. This is a summary report on the results obtained to date. The study evaluates the dependence of ballooning, Mercier and low-n ideal linear MHD stability on key system parameters to estimate overall MHD constraints for ITER. 17 refs., 27 figs

  10. Influence of electromagnetic pulse on the offspring sex ratio of male BALB/c mice.

    Science.gov (United States)

    Li, Jin-Hui; Jiang, Da-Peng; Wang, Ya-Feng; Yan, Jia-Jia; Guo, Qi-Yan; Miao, Xia; Lang, Hai-Yang; Xu, Sheng-Long; Liu, Jun-Ye; Guo, Guo-Zhen

    2017-09-01

    Public concern is growing about the exposure to electromagnetic fields (EMF) and its effect on male reproductive health. Detrimental effect of EMF exposure on sex hormones, reproductive performance and sex-ratio was reported. The present study was designed to clarify whether paternal exposure to electromagnetic pulse (EMP) affects offspring sex ratio in mice. 50 male BALB/c mice aged 5-6 weeks were exposed to EMP daily for 2 weeks before mated with non-exposed females at 0d, 7d, 14d, 21d and 28d after exposure. Sex hormones including total testosterone, LH, FSH, and GnRH were detected using radioimmunoassay. The sex ratio was examined by PCR and agarose gel electrophoresis. The results of D0, D21 and D28 showed significant increases compared with sham-exposed groups. The serum testosterone increased significantly in D0, D14, D21, and D28 compared with sham-exposed groups (p<0.05). Overall, this study suggested that EMP exposure may lead to the disturbance of reproductive hormone levels and affect the offspring sex ratio. Copyright © 2017. Published by Elsevier B.V.

  11. The VELOCE pulsed power generator for isentropic compression experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Tommy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Asay, James Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Chantrenne, Sophie J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hickman, Randall John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Willis, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Shay, Andrew W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Grine-Jones, Suzi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hall, Clint Allen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Baer, Melvin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center

    2007-12-01

    Veloce is a medium-voltage, high-current, compact pulsed power generator developed for isentropic and shock compression experiments. Because of its increased availability and ease of operation, Veloce is well suited for studying isentropic compression experiments (ICE) in much greater detail than previously allowed with larger pulsed power machines such as the Z accelerator. Since the compact pulsed power technology used for dynamic material experiments has not been previously used, it is necessary to examine several key issues to ensure that accurate results are obtained. In the present experiments, issues such as panel and sample preparation, uniformity of loading, and edge effects were extensively examined. In addition, magnetohydrodynamic (MHD) simulations using the ALEGRA code were performed to interpret the experimental results and to design improved sample/panel configurations. Examples of recent ICE studies on aluminum are presented.

  12. INCORPORATING AMBIPOLAR AND OHMIC DIFFUSION IN THE AMR MHD CODE RAMSES

    International Nuclear Information System (INIS)

    Masson, J.; Mulet-Marquis, C.; Chabrier, G.; Teyssier, R.; Hennebelle, P.

    2012-01-01

    We have implemented non-ideal magnetohydrodynamics (MHD) effects in the adaptive mesh refinement code RAMSES, namely, ambipolar diffusion and Ohmic dissipation, as additional source terms in the ideal MHD equations. We describe in details how we have discretized these terms using the adaptive Cartesian mesh, and how the time step is diminished with respect to the ideal case, in order to perform a stable time integration. We have performed a large suite of test runs, featuring the Barenblatt diffusion test, the Ohmic diffusion test, the C-shock test, and the Alfvén wave test. For the latter, we have performed a careful truncation error analysis to estimate the magnitude of the numerical diffusion induced by our Godunov scheme, allowing us to estimate the spatial resolution that is required to address non-ideal MHD effects reliably. We show that our scheme is second-order accurate, and is therefore ideally suited to study non-ideal MHD effects in the context of star formation and molecular cloud dynamics.

  13. Outline of fiscal 1969 achievements in research on MHD power generation; 1969 nendo MHD hatsuden kenkyu seika gaiyo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1969-07-01

    Compiled are the results of studies conducted in fiscal 1969 on MHD (magnetohydrodynamic) power generation. In the operation test and modification of the 1,000kW-class MHD power generator, the operation test continues from the preceding fiscal year using high-temperature air as oxidant, and the growth of boundary layer in the channel is determined. In the operation test of the MHD power generator designed for prolonged operation, insulation walls, electrode materials, and structures capable of prolonged operation are developed and tested. In the research of MHD power generator heat exchangers, studies are made about the bulkhead type and heat accumulator types (stationary type, rotary type, and falling-grain type). In addition, studies are conducted about seed collecting methods, MHD power generator electrode materials, heat-resisting insulators, and thermal performance rating. In the research and development of superconductive electromagnets, studies are conducted about superconductive electromagnets for 1kW MHD power generators, ferromagnetic superconductive electromagnets for 1,000kW-class MHD power generators, 45-kilogauss col type superconductive electromagnets, turbine type helium liquefier, high current density col type superconductive electromagnets, superinsulated magnetic field generators, etc. (NEDO)

  14. Predesign of an experimental (5 to 10 MWt) disk MHD facility and prospects of commercial (1,000 MWt) MHD/steam systems

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-07-01

    Experimental disk MHD facilities are predesigned, and commercial-scale (1,000 MWt) MHD/steam systems are investigated. The predesigns of the disk MHD facilities indicate that enthalpy extraction is 8.7% for a 10 MWt open cycle MHD generator, and increases to 37% for a 5 MWt closed cycle MHD generator. Commercial (1,000 MWt) MHD/steam systems are studied for 4 types. Of these types, the open cycle disk MHD generator shows the lowest efficiency of 42.8%, while the closed cycle disk MHD generator the highest efficiency of 50.0%. The open cycle linear generator, although showing an efficiency of 49.4%, may be the lowest-cost type, when the necessary heat source, heat exchangers and the like are taken into consideration. For the design of superconducting magnet, it is necessary to further investigate whether the one for the test facility is applicable to the commercial systems. (NEDO)

  15. Measurement of electromagnetic pulses generated during interactions of high power lasers with solid targets

    International Nuclear Information System (INIS)

    De Marco, M.; Krása, J.; Margarone, D.; Giuffrida, L.; Vrana, R.; Velyhan, A.; Korn, G.; Weber, S.; Cikhardt, J.; Pfeifer, M.; Krouský, E.; Ullschmied, J.; Ahmed, H.; Borghesi, M.; Kar, S.; Limpouch, J.; Velardi, L.; Side, D. Delle; Nassisi, V.

    2016-01-01

    A target irradiated with a high power laser pulse, blows off a large amount of charge and as a consequence the target itself becomes a generator of electromagnetic pulses (EMP) owing to high return current flowing to the ground through the target holder. The first measurement of the magnetic field induced by the neutralizing current reaching a value of a few kA was performed with the use of an inductive target probe at the PALS Laser Facility (Cikhardt et al. Rev. Sci. Instrum. 85 (2014) 103507). A full description of EMP generation should contain information on the spatial distribution and temporal variation of the electromagnetic field inside and outside of the interaction chamber. For this reason, we consider the interaction chamber as a resonant cavity in which different modes of EMP oscillate for hundreds of nanoseconds, until the EMP is transmitted outside through the glass windows and EM waves are attenuated. Since the experimental determination of the electromagnetic field distribution is limited by the number of employed antennas, a mapping of the electromagnetic field has to be integrated with numerical simulations. Thus, this work reports on a detailed numerical mapping of the electromagnetic field inside the interaction chamber at the PALS Laser Facility (covering a frequency spectrum from 100 MHz to 3 GHz) using the commercial code COMSOL Multiphysics 5.2. Moreover we carried out a comparison of the EMP generated in the parallelepiped-like interaction chamber used in the Vulcan Petawatt Laser Facility at the Rutherford Appleton Laboratory, against that produced in the spherical interaction chamber of PALS.

  16. FPGA-based Upgrade to RITS-6 Control System, Designed with EMP Considerations

    International Nuclear Information System (INIS)

    Anderson, Harold D.; Williams, John T.

    2009-01-01

    The existing control system for the RITS-6, a 20-MA 3-MV pulsed-power accelerator located at Sandia National Laboratories, was built as a system of analog switches because the operators needed to be close enough to the machine to hear pulsed-power breakdowns, yet the electromagnetic pulse (EMP) emitted would disable any processor-based solutions. The resulting system requires operators to activate and deactivate a series of 110-V relays manually in a complex order. The machine is sensitive to both the order of operation and the time taken between steps. A mistake in either case would cause a misfire and possible machine damage. Based on these constraints, a field-programmable gate array (FPGA) was chosen as the core of a proposed upgrade to the control system. An FPGA is a series of logic elements connected during programming. Based on their connections, the elements can mimic primitive logic elements, a process called synthesis. The circuit is static; all paths exist simultaneously and do not depend on a processor. This should make it less sensitive to EMP. By shielding it and using good electromagnetic interference-reduction practices, it should continue to operate well in the electrically noisy environment. The FPGA has two advantages over the existing system. In manual operation mode, the synthesized logic gates keep the operators in sequence. In addition, a clock signal and synthesized countdown circuit provides an automated sequence, with adjustable delays, for quickly executing the time-critical portions of charging and firing. The FPGA is modeled as a set of states, each state being a unique set of values for the output signals. The state is determined by the input signals, and in the automated segment by the value of the synthesized countdown timer, with the default mode placing the system in a safe configuration. Unlike a processor-based system, any system stimulus that results in an abort situation immediately executes a shutdown, with only a tens

  17. MHD instabilities and their effects on plasma confinement in the large helical device plasmas

    International Nuclear Information System (INIS)

    Toi, K.

    2002-01-01

    MHD stability of NBI heated plasmas and impacts of MHD modes on plasma confinement are intensively studied in the Large Helical Device (LHD). Three characteristic MHD instabilities were observed, that is, (1) pressure driven modes excited in the plasma edge, (2) pressure driven mode in the plasma core, and (3) Alfven eigenmodes (AEs) driven by energetic ions. MHD mode excited in the edge region accompanies multiple satellites, and is called Edge Harmonic Modes (EHMs). EHM sometimes has a bursting character. The bursting EHM transiently decreases the stored energy by about 15 percent. In the plasma core region, m=2/n=1 pressure driven mode is typically destabilized. The mode often induces internal collapse in the higher beta regime more than 1 percent. The internal collapse appreciably affects the global confinement. Energetic ion driven AEs are often detected in NBI-heated LHD plasmas. Particular AE with the frequency 8-10 times larger than TAE-frequency was detected in high beta plasmas more than 2 percent. The AE may be related to helicity-induced AE. Excitation of these three types of MHD instabilities and their impacts on plasma confinement are discussed. (author)

  18. Report of results of contract research. 'Research on magneto hydrodynamic (MHD) generation'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-03-01

    Examination was conducted in detail on an MHD generation system by coal combustion, with the results reported. Concerning a gas table calculation program in coal combustion, it was prepared assuming 100% slag removal ratio in the combustor as the primary approximation. A combustor for MHD generation needs to efficiently burn fuel using high temperature pre-heated air as the oxidant, to fully dissociate/electrolytically dissociate seed, and to supply to the generation channel a high speed combustion gas plasma having a high electrical conductivity which is required for MHD generation. This year, an examination was conducted on technological problems in burning coal in an MHD combustor. As for the NOx elimination system in an MHD generation plant, an examination was made if the method studied so far in MHD generation using heavy oil as the fuel is applicable to coal. Also investigated and reviewed were various characteristics, change in physical properties, recovery method, etc., in a mixed state of seed and slag in the case of coal combustion MHD. (NEDO)

  19. MHD-flow in slotted channels with conducting walls

    International Nuclear Information System (INIS)

    Evtushenko, I.A.; Kirillov, I.R.; Reed, C.B.

    1994-07-01

    A review of experimental results is presented for magnetohydrodynamic (MHD) flow in rectangular channels with conducting walls and high aspect ratios (longer side parallel to the applied magnetic field), which are called slotted channels. The slotted channel concept was conceived at Efremov Institute as a method for reducing MHD pressure drop in liquid metal cooled blanket design. The experiments conducted by the authors were aimed at studying both fully developed MHD-flow, and the effect of a magnetic field on the hydrodynamics of 3-D flows in slotted channels. Tests were carried out on five models of the slotted geometry. A good agreement between test and theoretical results for the pressure drop in slotted channels was demonstrated. Application of a open-quotes one-electrode movable probeclose quotes for velocity measurement permitted measurement of the M-shape velocity profiles in the slotted channels. Suppression of 3-D inertial effects in slotted channels of complex geometry was demonstrated based on potential distribution data

  20. MHD saga in the gases

    International Nuclear Information System (INIS)

    Petit, J.P.

    1995-01-01

    Jean-Pierre PETIT, one of the best MHD specialists, is telling this technology story and he is insisting on its military consequences. Civil MHD is only one iceberg emerged part, including a lot of leader technologies, interesting he defense. 3 notes

  1. 78 FR 35073 - Compass Efficient Model Portfolios, LLC and Compass EMP Funds Trust; Notice of Application

    Science.gov (United States)

    2013-06-11

    ... Balanced Fund, Compass EMP Multi-Asset Growth Fund, Compass EMP Alternative Strategies Fund, Compass EMP Balanced Volatility Weighted Fund, Compass EMP Growth Volatility Weighted Fund, and Compass EMP... Efficient Model Portfolios, LLC and Compass EMP Funds Trust; Notice of Application June 4, 2013. AGENCY...

  2. Generation of compressible modes in MHD turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jungyeon [Chungnam National Univ., Daejeon (Korea); Lazarian, A. [Univ. of Wisconsin, Madison, WI (United States)

    2005-05-01

    Astrophysical turbulence is magnetohydrodynamic (MHD) in nature. We discuss fundamental properties of MHD turbulence and in particular the generation of compressible MHD waves by Alfvenic turbulence and show that this process is inefficient. This allows us to study the evolution of different types of MHD perturbations separately. We describe how to separate MHD fluctuations into three distinct families: Alfven, slow, and fast modes. We find that the degree of suppression of slow and fast modes production by Alfvenic turbulence depends on the strength of the mean field. We review the scaling relations of the modes in strong MHD turbulence. We show that Alfven modes in compressible regime exhibit scalings and anisotropy similar to those in incompressible regime. Slow modes passively mimic Alfven modes. However, fast modes exhibit isotropy and a scaling similar to that of acoustic turbulence both in high and low {beta} plasmas. We show that our findings entail important consequences for star formation theories, cosmic ray propagation, dust dynamics, and gamma ray bursts. We anticipate many more applications of the new insight to MHD turbulence and expect more revisions of the existing paradigms of astrophysical processes as the field matures. (orig.)

  3. Electro-optic analysis of the influence of target geometry on electromagnetic pulses generated by petawatt laser-matter interactions

    Science.gov (United States)

    Robinson, Timothy; Giltrap, Samuel; Eardley, Samuel; Consoli, Fabrizio; De Angelis, Riccardo; Ingenito, Francesco; Stuart, Nicholas; Verona, Claudio; Smith, Roland A.

    2018-01-01

    We present an analysis of strong laser-driven electromagnetic pulses using novel electro-optic diagnostic techniques. A range of targets were considered, including thin plastic foils (20-550 nm) and mass-limited, optically-levitated micro-targets. Results from foils indicate a dependence of EMP on target thickness, with larger peak electric fields observed with thinner targets. Spectral analysis suggests high repeatability between shots, with identified spectral features consistently detected with earth following ejection of hot electrons from the plasma, in contrast to predictions for pin-mounted foils in the Poyé EMP generation model. With levitated targets, no EMP was measurable above the noise threshold of any diagnostic, despite observation of protons accelerated to >30 MeV energies, suggesting the discharge current contribution to EMP is dominant.

  4. Magnetic levitation and MHD propulsion

    International Nuclear Information System (INIS)

    Tixador, P.

    1994-01-01

    Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried our in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ..) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. (orig.)

  5. Magnetic levitation and MHD propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Tixador, P [CNRS/CRTBT-LEG, 38 - Grenoble (France)

    1994-04-01

    Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried our in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ..) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. (orig.).

  6. Report on results of contract research. 'Research on MHD generation system'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-03-01

    'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1980 reported. This year, a detailed conceptual design was carried out on a coal fired MHD generation system, with points for the technological development concretely examined. In addition, investigation was conducted on the progress of MHD generation technology, development situation of other generation systems, state of energy resources, etc., in various foreign countries. In the conceptual design of the coal fired MHD generation plant, the system structure of a 2,000 MWt class commercial MHD generation plant was explained, as were the conceptual design of the structural elements and proposals for a 500 MWt class demonstration plant and an 100 MWt class experimental plant, for example. In the overseas trend of R and D on MHD generation, investigations were made concerning the U.S., Soviet Union, and China, with details compiled for such items as generation plants, combustors, generation channels, heat resisting materials, superconducting magnets, heat exchangers, seed slags, inverters, boilers and environments, and commercial plants. (NEDO)

  7. The effects of electromagnetic pulse on the protein levels of tight junction associated-proteins in the cerebral cortex, hippocampus, heart, lung, and testis of rats.

    Science.gov (United States)

    Qiu, LianBo; Chen, Chen; Ding, GuiRong; Zhou, Yan; Zhang, MengYao

    2011-08-01

    To investigate changes in the expression of tight junction (TJ) proteins in the cerebral cortex, hippocampus, heart, lung, and testes of rats after exposure to electromagnetic pulse (EMP). Eighteen adult male Sprague-Dawley rats were divided into sham and exposure groups. The exposure groups received EMP at 200 kV/m for 200 pulses with a repetition rate of 1 Hz. The expression of TJ proteins (ZO-1, occludin, actin) in the several organs was examined by western blotting. ZO-1 levels in the cerebral cortex decreased 1 h and 3 h after EMP exposure compared with sham group (P<0.05). No significant difference was observed for occludin and actin. ZO-1 levels in the hippocampus increased 1 h and 3 h post-exposure (P<0.05), and occludin decreased after 3 h (P<0.05); however, actin was unaffected. ZO-1 levels in the heart increased 3 h post-exposure (P<0.05), occludin decreased 3 h post-exposure (P<0.05), and actin increased 1 h and 3 h post-exposure (P<0.05). ZO-1, occludin and actin levels in the lung decreased compared with those in the sham group (P<0.05). ZO-1 and occludin levels in the testes decreased 1 h and 3 h post-exposure (P<0.05), but actin showed no significant change. Exposure to EMP altered the expression levels of TJ proteins, particularly ZO-1, in the organs of adult male rats, which may induce changes in barrier structure and function. Copyright © 2011 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

  8. Criteria for Scaled Laboratory Simulations of Astrophysical MHD Phenomena

    International Nuclear Information System (INIS)

    Ryutov, D. D.; Drake, R. P.; Remington, B. A.

    2000-01-01

    We demonstrate that two systems described by the equations of the ideal magnetohydrodynamics (MHD) evolve similarly, if the initial conditions are geometrically similar and certain scaling relations hold. The thermodynamic properties of the gas must be such that the internal energy density is proportional to the pressure. The presence of the shocks is allowed. We discuss the applicability conditions of the ideal MHD and demonstrate that they are satisfied with a large margin both in a number of astrophysical objects, and in properly designed simulation experiments with high-power lasers. This allows one to perform laboratory experiments whose results can be used for quantitative interpretation of various effects of astrophysical MHD. (c) 2000 The American Astronomical Society

  9. Final report for EMP instrumentation project DNA IACRO 75-815: magnetic thin film sensors

    International Nuclear Information System (INIS)

    Hsieh, E.J.; Miller, D.E.; Vindelov, K.E.; Brown, T.G.

    1975-01-01

    The magnetic thin film current sensor/recorder is a passive device which responds to the peak current and pulse shape of a transient event. The transient current information becomes a permanent record on the film. The thin film device is small, low mass and reusable. It has been proven to be fast (less than 1/2 nanosecond response), radiation hard and applicable to peak current measurement of both CW and pulsed signals. The sensors were initially developed at LLL for pulse-energy measurement on exploding wires. Later the Defense Nuclear Agency sponsored the present project to develop the magnetic thin film devices as EMP diagnostic tools. The Air Force Weapons Lab supported the work to test the field capabilities of the thin film devices at ARES test facility, Kirtland AFB. Sandia Lab is now using a new version of the thin film sensors to monitor the transient current induced by intense radiation in their hybrid microcircuits. Also, a field test has been planned with Naval Electronics Laboratory Center where the thin film sensors are to be used to measure peak CW current caused by rf radiation. Research results are summarized

  10. Effect of Grain Size on Differential Desorption of Volatile Species and on Non-ideal MHD Diffusivity

    Science.gov (United States)

    Zhao, Bo; Caselli, Paola; Li, Zhi-Yun

    2018-05-01

    We developed a chemical network for modeling the chemistry and non-ideal MHD effects from the collapsing dense molecular clouds to protostellar disks. First, we re-formulated the cosmic-ray desorption rate by considering the variations of desorption rate over the grain size distribution. We find that the differential desorption of volatile species is amplified by the grains larger than 0.1 μm, because larger grains are heated to a lower temperature by cosmic-rays and hence more sensitive to the variations in binding energies. As a result, atomic nitrogen N is ˜2 orders of magnitude more abundant than CO; N2H+ also becomes a few times more abundant than HCO+ due to the increased gas-phase N2. However, the changes in ionization fraction due to freeze-out and desorption only have minor effects on the non-ideal MHD diffusivities. Our chemical network confirms that the very small grains (VSGs: below a few 100 Å) weakens the efficiency of both ambipolar diffusion and Hall effect. In collapsing dense cores, a maximum ambipolar diffusion is achieved when truncating the MRN size distribution at 0.1 μm, and for a maximum Hall effect, the truncation occurs at 0.04 μm. We conclude that the grain size distribution is crucial to the differential depletion between CO and N2 related molecules, as well as to the non-ideal MHD diffusivities in dense cores.

  11. Kinetic Modifications to MHD Phenomena in Toroidal Plasmas

    International Nuclear Information System (INIS)

    Cheng, C.Z.; Gorelenkov, N.N.; Kramer, G.J.; Fredrickson, E.

    2004-01-01

    Particle kinetic effects involving small spatial and fast temporal scales can strongly affect MHD phenomena and the long time behavior of plasmas. In particular, kinetic effects such as finite ion gyroradii, trapped particle dynamics, and wave-particle resonances have been shown to greatly modify the stability of MHD modes. Here, the kinetic effects of trapped electron dynamics and finite ion gyroradii are shown to have a large stabilizing effect on kinetic ballooning modes in low aspect ratio toroidal plasmas such as NSTX [National Spherical Torus Experiment]. We also present the analysis of Toroidicity-induced Alfven Eigenmodes (TAEs) destabilized by fast neutral-beam injected ions in NSTX experiments and TAE stability in ITER due to alpha-particles and MeV negatively charged neutral beam injected ions

  12. Modeling the dynamics of a storm-time acceleration event: combining MHD effects with wave-particle interactions

    Science.gov (United States)

    Elkington, S. R.; Alam, S. S.; Chan, A. A.; Albert, J.; Jaynes, A. N.; Baker, D. N.; Wiltberger, M. J.

    2017-12-01

    Global simulations of radiation belt dynamics are often undertaken using either a transport formalism (e.g. Fokker-Plank), or via test particle simulations in model electric and magnetic fields. While transport formalisms offer computational efficiency and the ability to deal with a wide range of wave-particle interactions, they typically rely on simplified background fields, and often are limited to empirically-specified stochastic (diffusive) wave-particle interactions. On the other hand, test particle simulations may be carried out in global MHD simulations that include realistic physical effects such as magnetopause shadowing, convection, and substorm injections, but lack the ability to handle physics outside the MHD approximation in the realm of higher frequency (kHz) wave populations.In this work we introduce a comprehensive simulation framework combining global MHD/test particle techniques to provide realistic background fields and radial transport processes, with a Stochastic Differential Equation (SDE) method for addressing high frequency wave-particle interactions. We examine the March 17, 2013 storm-time acceleration period, an NSF-GEM focus challenge event, and use the framework to examine the relative importance of physical effects such as magnetopause shadowing, diffusive and advective transport processes, and wave-particle interactions through the various phases of the storm.

  13. Active MHD control experiments in RFX-mod

    International Nuclear Information System (INIS)

    Ortolani, Sergio

    2006-01-01

    The RFX reversed field pinch experiment has been modified (RFX-mod) to address specific issues of active control of MHD instabilities. A thin shell (τ Bv ∼50 ms) has replaced the old thick one (τ Bv ∼500 ms) and 192 (4 poloidal x 48 toroidal) independently powered saddle coils surround the thin shell forming a cage completely covering the torus. This paper reports the results obtained during the first year of operation. The system has been used with various control scenarios including experiments on local radial field cancellation over the entire torus surface to mimic an ideal wall ('virtual shell') and on single and multiple mode feedback control. Successful virtual shell operation has been achieved leading to: a 3-fold increase in pulse length and well controlled 300 ms pulses(∼6 shell times) up to ∼1 MA plasma current; one order of magnitude reduction of the dominant radial field perturbations at the plasma edge and correspondingly 100% increase in global energy confinement time. Robust feedback stabilization of resistive wall modes has been demonstrated in conditions where rotation does not play a role and multiple unstable modes are present

  14. Integration of Extended MHD and Kinetic Effects in Global Magnetosphere Models

    Science.gov (United States)

    Germaschewski, K.; Wang, L.; Maynard, K. R. M.; Raeder, J.; Bhattacharjee, A.

    2015-12-01

    Computational models of Earth's geospace environment are an important tool to investigate the science of the coupled solar-wind -- magnetosphere -- ionosphere system, complementing satellite and ground observations with a global perspective. They are also crucial in understanding and predicting space weather, in particular under extreme conditions. Traditionally, global models have employed the one-fluid MHD approximation, which captures large-scale dynamics quite well. However, in Earth's nearly collisionless plasma environment it breaks down on small scales, where ion and electron dynamics and kinetic effects become important, and greatly change the reconnection dynamics. A number of approaches have recently been taken to advance global modeling, e.g., including multiple ion species, adding Hall physics in a Generalized Ohm's Law, embedding local PIC simulations into a larger fluid domain and also some work on simulating the entire system with hybrid or fully kinetic models, the latter however being to computationally expensive to be run at realistic parameters. We will present an alternate approach, ie., a multi-fluid moment model that is derived rigorously from the Vlasov-Maxwell system. The advantage is that the computational cost remains managable, as we are still solving fluid equations. While the evolution equation for each moment is exact, it depends on the next higher-order moment, so that truncating the hiearchy and closing the system to capture the essential kinetic physics is crucial. We implement 5-moment (density, momentum, scalar pressure) and 10-moment (includes pressure tensor) versions of the model, and use local approximations for the heat flux to close the system. We test these closures by local simulations where we can compare directly to PIC / hybrid codes, and employ them in global simulations using the next-generation OpenGGCM to contrast them to MHD / Hall-MHD results and compare with observations.

  15. A coupled systems code-CFD MHD solver for fusion blanket design

    Energy Technology Data Exchange (ETDEWEB)

    Wolfendale, Michael J., E-mail: m.wolfendale11@imperial.ac.uk; Bluck, Michael J.

    2015-10-15

    Highlights: • A coupled systems code-CFD MHD solver for fusion blanket applications is proposed. • Development of a thermal hydraulic systems code with MHD capabilities is detailed. • A code coupling methodology based on the use of TCP socket communications is detailed. • Validation cases are briefly discussed for the systems code and coupled solver. - Abstract: The network of flow channels in a fusion blanket can be modelled using a 1D thermal hydraulic systems code. For more complex components such as junctions and manifolds, the simplifications employed in such codes can become invalid, requiring more detailed analyses. For magnetic confinement reactor blanket designs using a conducting fluid as coolant/breeder, the difficulties in flow modelling are particularly severe due to MHD effects. Blanket analysis is an ideal candidate for the application of a code coupling methodology, with a thermal hydraulic systems code modelling portions of the blanket amenable to 1D analysis, and CFD providing detail where necessary. A systems code, MHD-SYS, has been developed and validated against existing analyses. The code shows good agreement in the prediction of MHD pressure loss and the temperature profile in the fluid and wall regions of the blanket breeding zone. MHD-SYS has been coupled to an MHD solver developed in OpenFOAM and the coupled solver validated for test geometries in preparation for modelling blanket systems.

  16. Characterizing electrostatic turbulence in tokamak plasmas with high MHD activity

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes-Filho, Z O; Santos Lima, G Z dos; Caldas, I L; Nascimento, I C; Kuznetsov, Yu K [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66316, 05315-970, Sao Paulo, SP (Brazil); Viana, R L, E-mail: viana@fisica.ufpr.b [Departamento de Fisica, Universidade Federal do Parana, Caixa Postal 19044, 81531-990, Curitiba, PR (Brazil)

    2010-09-01

    One of the challenges in obtaining long lasting magnetic confinement of fusion plasmas in tokamaks is to control electrostatic turbulence near the vessel wall. A necessary step towards achieving this goal is to characterize the turbulence level and so as to quantify its effect on the transport of energy and particles of the plasma. In this paper we present experimental results on the characterization of electrostatic turbulence in Tokamak Chauffage Alfven Bresilien (TCABR), operating in the Institute of Physics of University of Sao Paulo, Brazil. In particular, we investigate the effect of certain magnetic field fluctuations, due to magnetohydrodynamical (MHD) instabilities activity, on the spectral properties of electrostatic turbulence at plasma edge. In some TCABR discharges we observe that this MHD activity may increase spontaneously, following changes in the edge safety factor, or after changes in the radial electric field achieved by electrode biasing. During the high MHD activity, the magnetic oscillations and the plasma edge electrostatic turbulence present several common linear spectral features with a noticeable dominant peak in the same frequency. In this article, dynamical analyses were applied to find other alterations on turbulence characteristics due to the MHD activity and turbulence enhancement. A recurrence quantification analysis shows that the turbulence determinism radial profile is substantially changed, becoming more radially uniform, during the high MHD activity. Moreover, the bicoherence spectra of these two kinds of fluctuations are similar and present high bicoherence levels associated with the MHD frequency. In contrast with the bicoherence spectral changes, that are radially localized at the plasma edge, the turbulence recurrence is broadly altered at the plasma edge and the scrape-off layer.

  17. Neoclassical MHD equilibria with ohmic current

    International Nuclear Information System (INIS)

    Tokuda, Shinji; Takeda, Tatsuoki; Okamoto, Masao.

    1989-01-01

    MHD equilibria of tokamak plasmas with neoclassical current effects (neoclassical conductivity and bootstrap current) were calculated self-consistently. Neoclassical effects on JFT-2M tokamak plasmas, sustained by ohmic currents, were studied. Bootstrap currents flow little for L-mode type equilibria because of low attainable values of poloidal beta, β J . H-mode type equilibria give bootstrap currents of 30% ohmic currents for β J attained by JFT-2M and 100% for β J ≥ 1.5, both of which are sufficient to change the current profiles and the resultant MHD equilibria. Neoclassical conductivity which has roughly half value of the classical Spitzer conductivity brings peaked ohmic current profiles to yield low safety factor at the magnetic axis. Neoclassical conductivity reduces the value of effective Z(Z eff ) which is necessary to give the observed one-turn voltage but it needs impurities accumulating at the center when such peaked current profiles are not observed. (author)

  18. Influence of MHD effects and edge conditions on ITER helium ash accumulation and sustained ignition

    International Nuclear Information System (INIS)

    Redi, M.H.; Cohen, S.A.

    1990-06-01

    Dilution of reacting species by build-up of helium ash and its effect on ignition in the ITER tokamak have been studies in a series of simulations with the one-dimensional BALDUR transport code. Thermal diffusivities, obtained from ITER scaling laws and with radial variations observed in JET, gave τ E ∼ 2--4 sec. Refueling of deuterium and tritium maintained constant electron density, while carbon recycling was 100% and the helium ash recycling was varied from 1.0 to 0.5. Including MHD effects, specifically sawteeth and beta limits, we find that ignition can be sustained for 200 seconds with R helium = 0.95. These simulations, the only non-zero-dimensional, time-dependent simulations thus far made for ITER plasmas, emphasize that edge plasma conditions, MHD behavior, and helium particle transport are critical synergistic issues for sustained ignition. 27 refs., 2 figs., 1 tab

  19. The effects of imperfect insulator coatings on MHD and heat transfer in rectangular duct

    International Nuclear Information System (INIS)

    Ying, A.Y.; Gaizer, A.A.

    1994-01-01

    In self cooled liquid metal blankets, the use of an insulator coating to reduce the flow of the eddy current to the structure leads to a significant reduction in MHD pressure drop. Furthermore, this insulating layer alters the velocity structure by reducing the potential difference between the side wall and boundary layer. The questions which arise are: (1) How the imperfections in the insulator coating affect the velocity profiles and their consequent impacts on heat transfer performance?; and, (2) How much crack can lead to an unacceptable MHD pressure drop? The dynamics of the crack healing in an insulator coating duct is one of the important subjects requiring study. The purpose of this work is to present numerical simulations of fully developed MHD flow and developing heat transfer characteristics in imperfectly insulated ducts, and to quantify the influences of crack locations, sizes and resistivities on 2-D MHD pressure drops. Comparisons of finite element solutions of pressure drops in partially insulated ducts with analytical solutions obtained from a circuit analogy show excellent agreement. In addition, the remarkable side layer velocity profile observed in a laminar MHD flow of a conducting duct gradually diminishes as the resistance of the insulating layer increases. The average side wall Nusselt number drops by a factor of 2 as the duct becomes fully insulated

  20. Spectrum of resistive MHD modes in cylindrical plasmas

    International Nuclear Information System (INIS)

    Ryu, C.M.; Grimm, R.C.

    1983-07-01

    A numerical study of the normal modes of a compressible resistive MHD fluid in cylindrical geometry is presented. Resistivity resolves the shear Alfven and slow magnetosonic continua of ideal MHD into discrete spectra and gives rise to heavily damped modes whose frequencies lie on specific lines in the complex plane. Fast magnetosonic waves are less affected but are also damped. Overstable modes arise from the shear Alfven spectrum. The stabilizing effect of favorable average curvature is shown. Eigenfunctions illustrating the nature of typical normal modes are displayed

  1. MHD power generation for the synthetic-fuels industry

    International Nuclear Information System (INIS)

    Jones, M.S. Jr.

    1982-01-01

    The integration of open cycle MHD with various processes for the recovery of hydrocarbons for heavy oil deposits, oil sands, and oil shales are examined along with its use in producing medium Btu gas, synthetic natural gas and solvent refined coal. The major features of the MHD cycle which are of interest are: (a) the ability to produce hydrogen through the shift reaction by introducing H 2 O into the substoichiometric combustion product flow exiting the MHD diffuser, (b) the use of high temperature waste heat in the MHD exhaust, and (c) the ability of the seed in the MHD flow to remove sulfur from the combustion products. Therefore the use of the MHD cycle allows coal to be used in an environmentally acceptable manner in place of hydrocarbons which are now used to produce process heat and hydrogen. The appropriate plant sizes are in the range of 25 to 50 MWe and the required MHD generator enthalpy extraction efficiencies are low. Sale of electricity produced, over and above that used in the process, can provide a revenue stream which can improve the economics of the hydrocarbon processing. This, coupled with the replacement of coal for hydrocarbons in certain phases of the process, should improve the overall economics, while not requiring a high level of performance by the MHD components. Therefore, this area should be an early target of opportunity for the commercialization of MHD

  2. Instrument to synchronize Thomson scattering diagnostic measurements with MHD acitivity in a tokamak

    International Nuclear Information System (INIS)

    Wintenberg, A.L.

    1985-04-01

    An instrument to synchronize the firing of a ruby laser for a Thomson scattering diagnostic with plasma oscillations was designed, developed, and evaluated. The instrument will fire the laser at a user-selected phase of an input sine or sawtooth wave with an accuracy of +-15 0 . Allowable frequencies range from 20 to 500 Hz for a sawtooth and from 1 to 30 kHz for a sine wave. The instrument also allows synchronization with a sine wave to be enabled by a preselected sawtooth phase. The instrument uses analog signal processing circuits to separate the signal components, remove unwanted components, and produce zero-phase synchronization pulses. The instrument measures the period between zero-phase pulses in order to produce phase synchronization pulses delayed a fraction of the period from the zero-phase pulses. The laser is fired by the phase synchronization pulse. Unwanted signal components are attenuated by bandpass filters. A digitally controlled self-adjusting bandpass filter for sine processing. The instrument was used to investigate the variation of the electron temperature profile with the phase of the x-ray signal from an Impurity Studies Experiment (ISX-B) plasma exhibiting magnetohydrodynamic (MHD) activity

  3. End Effects on the Linear Induction MHD Generator Calculated by Two-Sided Laplace Transform

    Energy Technology Data Exchange (ETDEWEB)

    Engeln, F.; Peschka, W. [Deutsche Versuchsanstalt fuer Luft- und Raumfahrt e.V., Institut fuer Energiewandlung und Elektrische Antriebe, Stuttgart, Federal Republic of Germany (Germany)

    1966-11-15

    In induction MHD systems special problems occur where the flow enters or leaves the magnetic field. These problems are generally described as end effects. Large gradients of the magnetic field are present at the inlet and also at the outlet of an MHD induction engine, these generating electric current systems in the fluid which may spoil the performance characteristics of the generator due to the interaction with the primary field of the engine. The two-dimensional induction MHD generator of finite length, using a polyphase winding system to obtain a travelling magnetic field, is treated as a boundary value problem by two-sided Laplace transform. For simplicity incompressibility is assumed. The two- dimensional boundary value problem of the induction engine is solved for - {infinity} Less-Than-Over-Equal-To x Less-Than-Over-Equal-To {infinity}. x is parallel to the flow direction of the linear MHD generator. In the region 0 Less-Than-Over-Equal-To x Less-Than-Over-Equal-To L the magnetic travelling wave is sinusoidal with a cyclical frequency {omega} and a phase-velocity v{sub s}. At x = 0 the conducting incompressible working fluid enters the field region and leaves it at the point-x = L. Two mathematical methods can be used to solve the boundary value problem, the Fourier transform or the two-sided Laplace transform. The latter offers the advantage of representing a complex analytical function in the image space. Moreover, it is possible to obtain the characteristics of the generator in the image space (e. g. field configuration, power flow function, etc.). That implies a large simplification of mathematical treatment. The solution in the original space then is given by asymptotic expansion of the known image function. (author)

  4. Study of MHD stability beta limit in LHD by hierarchy integrated simulation code

    International Nuclear Information System (INIS)

    Sato, M.; Watanabe, K.Y.; Nakamura, Y.

    2008-10-01

    The beta limit by the ideal MHD instabilities (so-called 'MHD stability beta limit') for helical plasmas is studied by a hierarchy integrated simulation code. A numerical model for the effect of the MHD instabilities is introduced such that the pressure profile is flattened around the rational surface due to the MHD instabilities. The width of the flattening of the pressure gradient is determined from the width of the eigenmode structure of the MHD instabilities. It is assumed that there is the upper limit of the mode number of the MHD instabilities which directly affect the pressure gradient. The upper limit of the mode number is determined using a recent high beta experiment in the Large Helical Device (LHD). The flattening of the pressure gradient is calculated by the transport module in a hierarchy integrated code. The achievable volume averaged beta value in the LHD is expected to be beyond 6%. (author)

  5. Report of results of contract research. 'Research on magneto hydrodynamic (MHD) generation'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-03-01

    Examination was conducted in detail on an MHD generation system by coal combustion, with the results reported. Concerning a gas table calculation program in coal combustion, it was prepared assuming 100% slag removal ratio in the combustor as the primary approximation. A combustor for MHD generation needs to efficiently burn fuel using high temperature pre-heated air as the oxidant, to fully dissociate/electrolytically dissociate seed, and to supply to the generation channel a high speed combustion gas plasma having a high electrical conductivity which is required for MHD generation. This year, an examination was conducted on technological problems in burning coal in an MHD combustor. As for the NOx elimination system in an MHD generation plant, an examination was made if the method studied so far in MHD generation using heavy oil as the fuel is applicable to coal. Also investigated and reviewed were various characteristics, change in physical properties, recovery method, etc., in a mixed state of seed and slag in the case of coal combustion MHD. (NEDO)

  6. Engineering design and development of lead lithium loop for thermo-fluid MHD studies

    International Nuclear Information System (INIS)

    Kumar, M.; Patel, Anita; Jaiswal, A.; Ranjan, A.; Mohanta, D.; Sahu, S.; Saraswat, A.; Rao, T.S.; Mehta, V.; Bhattacharyay, R.; Rajendra Kumar, E.

    2017-01-01

    In the frame of the design and development of LLCB TBM, number of R and D activities is in progress in the area of Pb-Li technology development. Molten Pb-Li is used as a tritium breeder and also as a coolant for the internals of the TBM structure. In presence of strong plasma confining toroidal magnetic field, motion of electrically conducting Pb-Li leads to Magneto Hydro Dynamic (MHD) phenomena, as a consequence of which the flow profile of Pb-Li is significantly modified inside the Pb-Li channels of TBM. This causes additional pressure drop inside TBM and affects the heat transfer from internal structure. The detail studies of these MHD effects are of prime importance for successful design of LLCB TBM and its performance evaluation. Although, various numerical MHD codes have been developed, validated in simple flow configuration and are being used to study MHD phenomena in LLCB TBM, experimental validation of these codes in TBM relevant complex flow geometry is yet to be performed. A Pb-Li MHD experimental loop is, therefore, being developed at IPR to perform thermo-fluid MHD experiments in various LLCB TBM relevant flow configuration. MHD experiments are planned with different test sections instrumented with potential pins, thermo couples, etc. under a uniform magnetic field of ∼1.4 T. The obtained experimental data will be analyzed to understand the MHD phenomena in TBM like flow configuration and also for validation of MHD codes. This paper describes the detailed process as well as engineering design of the Pb-Li MHD loop and its major components along with the plan of MHD experiments in various test mock ups. (author)

  7. Modeling and analysis of the disk MHD generator component of a gas core reactor/MHD Rankine cycle space power system

    International Nuclear Information System (INIS)

    Welch, G.E.; Dugan, E.T.; Lear, W.E. Jr.; Appelbaum, J.G.

    1990-01-01

    A gas core nuclear reactor (GCR)/disk magnetohydrodynamic (MHD) generator direct closed Rankine space power system concept is described. The GCR/disk MHD generator marriage facilitates efficient high electric power density system performance at relatively high operating temperatures. The system concept promises high specific power levels, on the order of 1 kW e /kg. An overview of the disk MHD generator component magnetofluiddynamic and plasma physics theoretical modeling is provided. Results from a parametric design analysis of the disk MHD generator are presented and discussed

  8. Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft

    International Nuclear Information System (INIS)

    Myrabo, L.N.; Rosa, R.J.

    2004-01-01

    Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant 'Mercury' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a 'tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off and landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic 'mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond 'idle' power, or virtually 'disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely 'green' and independent of Earth's limited fossil fuel reserves

  9. Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft

    Science.gov (United States)

    Myrabo, L. N.; Rosa, R. J.

    2004-03-01

    Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant ``Mercury'' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a `tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off & landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic `mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond `idle' power, or virtually `disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely `green' and independent of Earth's limited fossil fuel reserves.

  10. EMP Threats to US National Security: Congressional Responses

    Science.gov (United States)

    Huessy, Peter

    2011-04-01

    The US Congress is considering how best to respond to concerns that EMP is a real and present danger to US security. The threats come from a variety of areas: solar storms, non-nuclear EMP from man-made machines and devices; and nuclear EMP from a nuclear device exploded above CONUS or other critical areas important to the United States and its allies. Responses have to date included passage in the House of legislation to protect the electrical grid in the United States from such threats and hearings before the Homeland Security Committee. Additional efforts include examining missile defense responses, protection of the maritime domain, and hardening of US military and related civilian infrastructure. The House of Representatives has also examined what Europe, the European Union and NATO, both government and private industry, have done in these areas. Complicating matters are related issues of cyber-security and overall homeland security priorities.

  11. Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report

    International Nuclear Information System (INIS)

    Tataronis, J. A.

    2004-01-01

    This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfven continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named ''accumulation continuum'' and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory

  12. Parallelized FDTD simulation for flat-plate bounded wave EMP simulator with lumped terminator

    International Nuclear Information System (INIS)

    Zhu Xiangqin; Chen Weiqing; Chen Zaigao; Cai Libing; Wang Jianguo

    2013-01-01

    A parallelized finite-difference time-domain(FDTD) method for simulating the bounded wave electromagnetic pulse (EMP) simulator with lumped terminator and parallel plate is presented. The effects of several model-parameters on the simulator to the fields in the working volume are simulated and analyzed. The results show that if the width of the lower PEC plate is(or is bigger than)1.5 times that of the upper plate of working volume, the projection length of front transitional section does not have a significant effect on the rise-times of electric fields at the points near the front transitional section, and the rise-times of electric fields at the points near the working volume center decrease as the projection length increases, but the decrement of rise-time decreases. The rise-times of E z at all points also decrease as the lower PEC plate's width increases, but the decrements of rise-time decreases. If the projection length of the front transitional section is fixed, the good results can not be obtained by increasing or decreasing the height of the simulator only, however, which has an optimal value. (authors)

  13. Increasing the magnetic helicity content of a plasma by pulsing a magnetized source.

    Science.gov (United States)

    Woodruff, S; Stallard, B W; McLean, H S; Hooper, E B; Bulmer, R; Cohen, B I; Hill, D N; Holcomb, C T; Moller, J; Wood, R D

    2004-11-12

    By operating a magnetized coaxial gun in a pulsed mode it is possible to produce large voltage pulses of duration approximately 500 mus while reaching a few kV, giving a discrete input of helicity into a spheromak. In the sustained spheromak physics experiment (SSPX), it is observed that pulsing serves to nearly double the stored magnetic energy and double the temperature. We discuss these results by comparison with 3D MHD simulations of the same phenomenon.

  14. Long-term electromagnetic pulse exposure induces Abeta deposition and cognitive dysfunction through oxidative stress and overexpression of APP and BACE1.

    Science.gov (United States)

    Jiang, Da-Peng; Li, Jin-Hui; Zhang, Jie; Xu, Sheng-Long; Kuang, Fang; Lang, Hai-Yang; Wang, Ya-Feng; An, Guang-Zhou; Li, Jing; Guo, Guo-Zhen

    2016-07-01

    A progressively expanded literature has been devoted in the past years to the noxious or beneficial effects of electromagnetic field (EMF) to Alzheimer׳s disease (AD). This study concerns the relationship between electromagnetic pulse (EMP) exposure and the occurrence of AD in rats and the underlying mechanisms, focusing on the role of oxidative stress (OS). 55 healthy male Sprague Dawley (SD) rats were used and received continuous exposure for 8 months. Morris water maze (MWM) test was conducted to test the ability of cognitive and memory. The level of OS was detected by superoxide dismutase (SOD) activity and glutathione (GSH) content. We found that long-term EMP exposure induced cognitive damage in rats. The content of β-amyloid (Aβ) protein in hippocampus was increased after long-term EMP exposure. OS of hippocampal neuron was detected. Western blotting and immunohistochemistry (IHC) assay showed that the content of Aβ protein and its oligomers in EMP-exposed rats were higher than that of sham-exposed rats. The content of Beta Site App Cleaving Enzyme (BACE1) and microtubule-associated protein 1 light chain 3-II (LC3-II) in EMP-exposed rats hippocampus were also higher than that of sham-exposed rats. SOD activity and GSH content in EMP-exposed rats were lower than sham-exposed rats (p<0.05). Several mechanisms were proposed based on EMP exposure-induced OS, including increased amyloid precursor protein (APP) aberrant cleavage. Although further study is needed, the present results suggest that long-term EMP exposure is harmful to cognitive ability in rats and could induce AD-like pathological manifestation. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Nuclear EMP simulation for large-scale urban environments. FDTD for electrically large problems.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, William S. [Los Alamos National Laboratory; Bull, Jeffrey S. [Los Alamos National Laboratory; Wilcox, Trevor [Los Alamos National Laboratory; Bos, Randall J. [Los Alamos National Laboratory; Shao, Xuan-Min [Los Alamos National Laboratory; Goorley, John T. [Los Alamos National Laboratory; Costigan, Keeley R. [Los Alamos National Laboratory

    2012-08-13

    In case of a terrorist nuclear attack in a metropolitan area, EMP measurement could provide: (1) a prompt confirmation of the nature of the explosion (chemical or nuclear) for emergency response; and (2) and characterization parameters of the device (reaction history, yield) for technical forensics. However, urban environment could affect the fidelity of the prompt EMP measurement (as well as all other types of prompt measurement): (1) Nuclear EMP wavefront would no longer be coherent, due to incoherent production, attenuation, and propagation of gamma and electrons; and (2) EMP propagation from source region outward would undergo complicated transmission, reflection, and diffraction processes. EMP simulation for electrically-large urban environment: (1) Coupled MCNP/FDTD (Finite-difference time domain Maxwell solver) approach; and (2) FDTD tends to be limited to problems that are not 'too' large compared to the wavelengths of interest because of numerical dispersion and anisotropy. We use a higher-order low-dispersion, isotropic FDTD algorithm for EMP propagation.

  16. Technical support for open-cycle MHD program

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-05-01

    The support program for open-cycle MHD at Argonne National Lab is developing the analytical tools needed to investigate the performance of the major components in the combined-cycle MHD/steam power system. The analytical effort is centered on the primary components of the system that are unique to MHD and also on the integration of these analytical representations into a model of the entire power producing system. The present project activities include modeling of the combustor, MHD channel, slag separator, and the high-temperature air preheater. In addition, these models are combined into a complete system model, which is at present capable of carrying out optimizations of the entire system on either thermodynamic efficiency or with less confidence, cost of electrical power. Also, in support of the open-cycle program, considerable effort has gone into the formulation of a CDIF Test Plan and a National MHD Test Program.

  17. MHD stability of JET high performance discharges. Comparison of MHD calculations with experimental observations

    International Nuclear Information System (INIS)

    Huysmans, G.

    1998-03-01

    One of the aims of the JET, the Joint European Torus, project is to optimise the maximum fusion performance as measured by the neutron rate. At present, two different scenarios are developed at JET to achieve the high performance the so-called Hot-Ion H-mode scenario and the more recent development of the Optimised Shear scenario. Both scenarios have reached similar values of the neutron rate in Deuterium plasmas, up to 5 10 17 neutrons/second. Both scenarios are characterised by a transport barrier, i.e., a region in the plasma where the confinement is improved. The Hot-Ion H-mode has a transport barrier at the plasma boundary just inside the separatrix, an Optimised Shear plasma exhibits a transport barrier at about mid radius. Associated with the improved confinement of the transport barriers are locally large pressure gradients. It is these pressure gradients which, either directly or indirectly, can drive MHD instabilities. The instabilities limit the maximum performance. In the optimised shear scenario a global MHD instability leads to a disruptive end of the discharge. In the Hot-Ion H-mode plasmas, so-called Outer Modes can occur which are localised at the plasma boundary and lead to a saturation of the plasma performance. In this paper, two examples of the MHD instabilities are discussed and identified by comparing the experimentally observed modes with theoretical calculations from the ideal MHD code MISHKA-1. Also, the MHD stability boundaries of the two scenarios are presented. Section 3 contains a discussion of the mode observed just before the disruption

  18. Gravitational instability in isotropic MHD plasma waves

    Science.gov (United States)

    Cherkos, Alemayehu Mengesha

    2018-04-01

    The effect of compressive viscosity, thermal conductivity and radiative heat-loss functions on the gravitational instability of infinitely extended homogeneous MHD plasma has been investigated. By taking in account these parameters we developed the six-order dispersion relation for magnetohydrodynamic (MHD) waves propagating in a homogeneous and isotropic plasma. The general dispersion relation has been developed from set of linearized basic equations and solved analytically to analyse the conditions of instability and instability of self-gravitating plasma embedded in a constant magnetic field. Our result shows that the presence of viscosity and thermal conductivity in a strong magnetic field substantially modifies the fundamental Jeans criterion of gravitational instability.

  19. Combined effects of radiation and chemical reaction on MHD flow ...

    African Journals Online (AJOL)

    (2016) have studied unsteady MHD flow in porous media over exponentially accelerated plate ... boundary layer flow of heat and mass transfer over a moving vertical plate with suction. ... flow considering free convection over a porous plate.

  20. Report on results of contract research. 'Research on MHD generation system'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-03-01

    'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1980 reported. This year, a detailed conceptual design was carried out on a coal fired MHD generation system, with points for the technological development concretely examined. In addition, investigation was conducted on the progress of MHD generation technology, development situation of other generation systems, state of energy resources, etc., in various foreign countries. In the conceptual design of the coal fired MHD generation plant, the system structure of a 2,000 MWt class commercial MHD generation plant was explained, as were the conceptual design of the structural elements and proposals for a 500 MWt class demonstration plant and an 100 MWt class experimental plant, for example. In the overseas trend of R and D on MHD generation, investigations were made concerning the U.S., Soviet Union, and China, with details compiled for such items as generation plants, combustors, generation channels, heat resisting materials, superconducting magnets, heat exchangers, seed slags, inverters, boilers and environments, and commercial plants. (NEDO)

  1. Magnetohydrodynamic (MHD) simulation of solar prominence formation

    International Nuclear Information System (INIS)

    Bao, J.

    1987-01-01

    Formation of Kippenhahn-Schluter type solar prominences by chromospheric mass injection is studied via numerical simulation. The numerical model is based on a two-dimensional, time-dependent magnetohydrodynamic (MHD) theory. In addition, an analysis of gravitational thermal MHD instabilities related to condensation is performed by using the small-perturbation method. The conclusions are: (1) Both quiescent and active-region prominences can be formed by chromospheric mass injection, provided certain optimum conditions are satisfied. (2) Quiescent prominences cannot be formed without condensation, though enough mass is supplied from chromosphere. The mass of a quiescent prominence is composed of both the mass injected from the chromosphere and the mass condensed from the corona. On the other hand, condensation is not important to active region prominence formation. (3) In addition to channeling and supporting effects, the magnetic field plays another important role, i.e. containing the prominence material. (4) In the model cases, prominences are supported by the Lorentz force, the gas-pressure gradient and the mass-injection momentum. (5) Due to gravity, more MHD condensation instability modes appear in addition to the basic condensation mode

  2. A cross-country Exchange Market Pressure (EMP dataset

    Directory of Open Access Journals (Sweden)

    Mohit Desai

    2017-06-01

    Full Text Available The data presented in this article are related to the research article titled - “An exchange market pressure measure for cross country analysis” (Patnaik et al. [1]. In this article, we present the dataset for Exchange Market Pressure values (EMP for 139 countries along with their conversion factors, ρ (rho. Exchange Market Pressure, expressed in percentage change in exchange rate, measures the change in exchange rate that would have taken place had the central bank not intervened. The conversion factor ρ can interpreted as the change in exchange rate associated with $1 billion of intervention. Estimates of conversion factor ρ allow us to calculate a monthly time series of EMP for 139 countries. Additionally, the dataset contains the 68% confidence interval (high and low values for the point estimates of ρ’s. Using the standard errors of estimates of ρ’s, we obtain one sigma intervals around mean estimates of EMP values. These values are also reported in the dataset.

  3. A cross-country Exchange Market Pressure (EMP) dataset.

    Science.gov (United States)

    Desai, Mohit; Patnaik, Ila; Felman, Joshua; Shah, Ajay

    2017-06-01

    The data presented in this article are related to the research article titled - "An exchange market pressure measure for cross country analysis" (Patnaik et al. [1]). In this article, we present the dataset for Exchange Market Pressure values (EMP) for 139 countries along with their conversion factors, ρ (rho). Exchange Market Pressure, expressed in percentage change in exchange rate, measures the change in exchange rate that would have taken place had the central bank not intervened. The conversion factor ρ can interpreted as the change in exchange rate associated with $1 billion of intervention. Estimates of conversion factor ρ allow us to calculate a monthly time series of EMP for 139 countries. Additionally, the dataset contains the 68% confidence interval (high and low values) for the point estimates of ρ 's. Using the standard errors of estimates of ρ 's, we obtain one sigma intervals around mean estimates of EMP values. These values are also reported in the dataset.

  4. Tokamak experiments on JIPP T-II with pulsed gas injection

    International Nuclear Information System (INIS)

    Toi, K.; Itoh, S.; Fujita, J.; Kadota, K.; Kawahata, K.

    1978-02-01

    The confinement of tokamak plasma has been investigated in the wide range of electron density average n sub(e) from 1 x 10 13 to 5 x 10 13 cm -3 by using the pulsed gas injection. The gross energy confinement time increases with increase of electron density and reaches 14 msec. The averaged effective ionic charge derived from plasma conductivity = is about 1 to 2 in the regime of small streaming parameter ( = 0.01 -- 0.08). The ratio of ion temperature to electron one is in the range greater than 0.5. This fact means that the ion energy confinement time is greater than the electron-ion energy relaxation time. Excessive injection of cold neutral gas excites m = 2 MHD oscillations. Much more gas injection leads to the remarkable cooling of plasma periphery and disruptive instabilities. These MHD oscillations and disruptive instabilities have been suppressed by the heating of plasma periphery with the second rapid rise of plasma current. (auth.)

  5. Overview of liquid-metal MHD

    International Nuclear Information System (INIS)

    Dunn, P.F.

    1978-01-01

    The basic features of the two-phase liquid-metal MHD energy conversion under development at Argonne National Laboratory are presented. The results of system studies on the Rankine-cycle and the open-cycle coal-fired cycle options are discussed. The liquid-metal MHD experimental facilities are described in addition to the system's major components, the generator, mixer and nozzle-separator-diffuser

  6. Stability of a two-volume MRxMHD model in slab geometry

    Science.gov (United States)

    Tuen, Li Huey

    Ideal MHD models are known to be inadequate to describe various physical attributes of a toroidal field with non-continuous symmetry, such as magnetic islands and stochastic regions. Motivated by this omission, a new variational principle MRXMHD was developed; rather than include an infinity of magnetic flux surfaces, MRxMHD has a finite number of flux surfaces, and thus supports partial plasma relaxation. The model comprises of relaxed plasma regions which are separated by nested ideal MHD interfaces (flux surfaces), and can be encased in a perfectly conducting wall. In each region the pressure is constant, but can jump across interfaces. The field and field pitch, or rotational transform, can also jump across the interfaces. Unlike ideal MHD, MRxMHD plasmas can support toroidally non-axisymmetric confined magnetic fields, magnetic islands and stochastic regions. In toroidally non-axisymmetric plasma, the existence of interfaces in MRxMHD is contingent on the irrationality of the rotational transform of flux surfaces. That is, the KAM theorem shows that invariant tori (flux surfaces) continue to exist for sufficiently small perturbations to an integrable system (which describes flux surfaces), provided that the rotational transform is sufficiently irrational. Building upon the MRxMHD stability model, we study the effects of irrationality of the rotational transform at interfaces in MRxMHD on plasma stability. We present an MRxMHD equilibrium model to investigate the effects of magnetic field pitch within the plasma and across the aforementioned flux surfaces within a chosen geometry. In this model, it is found that the 2D system stability conditions are dependent on the interface and resonant surface magnetic field pitch at minimised energy states, and the stability of a system as a function of magnetic field pitch destabilises at particular values of magnetic field pitch. We benchmark the treatment of a two-volume system, along with the calculations for

  7. Scaling, Intermittency and Decay of MHD Turbulence

    International Nuclear Information System (INIS)

    Lazarian, A.; Cho, Jungyeon

    2005-01-01

    We discuss a few recent developments that are important for understanding of MHD turbulence. First, MHD turbulence is not so messy as it is usually believed. In fact, the notion of strong non-linear coupling of compressible and incompressible motions along MHD cascade is not tenable. Alfven, slow and fast modes of MHD turbulence follow their own cascades and exhibit degrees of anisotropy consistent with theoretical expectations. Second, the fast decay of turbulence is not related to the compressibility of fluid. Rates of decay of compressible and incompressible motions are very similar. Third, viscosity by neutrals does not suppress MHD turbulence in a partially ionized gas. Instead, MHD turbulence develops magnetic cascade at scales below the scale at which neutrals damp ordinary hydrodynamic motions. Forth, density statistics does not exhibit the universality that the velocity and magnetic field do. For instance, at small Mach numbers the density is anisotropic, but it gets isotropic at high Mach numbers. Fifth, the intermittency of magnetic field and velocity are different. Both depend on whether the measurements are done in a local system of reference oriented along the local magnetic field or in the global system of reference related to the mean magnetic field

  8. Alpha particle effects on MHD ballooning

    International Nuclear Information System (INIS)

    1991-01-01

    During the period, as the first step towards the goal of detail understanding of the effects of alpha particle on MHD Ballooning Modes, a new numerical approach to investigate the stability of low-frequency fluctuations in high temperature tokamaks was developed by solving the gyrokinetic equations for the ion and electron directly as an initial value problem. The advantage of this approach is the inclusion of many important kinetic features of the problem without approximations and computationally more economical than particle-pushing simulation. The ion-temperature-gradient-mode was investigated to benchmark this new simulation technique. Previous results in literature were recovered. Both the adiabatic electron model and the full drift-kinetic electron model are studied. Numerical result shows that the full drift-kinetic electron model is more unstable. The development of subcycling technique to handle the fast electron bounce time is particularly significant to apply this new approach to the alpha particle problem since alpha particle bounce frequency is also significantly higher than the mode frequency. This new numerical technique will be the basis of future study of the microstability in high temperature tokamaks with alpha particles (or any energetic species). 15 refs., 13 figs

  9. Multi-scale-nonlinear interactions among macro-MHD mode, micro-turbulence, and zonal flow

    International Nuclear Information System (INIS)

    Ishizawa, Akihiro; Nakajima, Noriyoshi

    2007-01-01

    This is the first numerical simulation demonstrating that macro-magnetohydrodynamic (macro-MHD) mode is exited as a result of multi-scale interaction in a quasi-steady equilibrium formed by a balance between zonal flow and micro-turbulence via reduced-two-fluid simulation. Only after obtaining the equilibrium which includes zonal flow and the turbulence caused by kinetic ballooning mode is this simulation of macro-MHD mode, double tearing mode, accomplished. In the quasi-steady equilibrium a macro-fluctuation which has the same helicity as that of double tearing mode is a part of the turbulence until it grows as a macro-MHD mode finally. When the macro-MHD grows it effectively utilize free energy of equilibrium current density gradient because of positive feedback loop between suppression of zonal flow and growth of the macro-fluctuation causing magnetic reconnection. Thus once the macro-MHD grows from the quasi-equilibrium, it does not go back. This simulation is more comparable with experimental observation of growing macro-fluctuation than traditional MHD simulation of linear instabilities in a static equilibrium. (author)

  10. Effect of bootstrap current on MHD equilibrium beta limit in heliotron plasmas

    International Nuclear Information System (INIS)

    Watanabe, K.Y.

    2001-01-01

    The effect of bootstrap current on the beta limit of MHD equilibria is studied systematically by an iterative calculation of MHD equilibrium and the consistent bootstrap current in high beta heliotron plasmas. The LHD machine is treated as a standard configuration heliotron with an L=2 planar axis. The effects of vacuum magnetic configurations, pressure profiles and the vertical field control method are studied. The equilibrium beta limit with consistent bootstrap current is quite sensitive to the magnetic axis location for finite beta, compared with the currentless cases. For a vacuum configuration with the magnetic axis shifted inwards in the torus, even in the high beta regimes, the bootstrap current flows to increase the rotational transform, leading to an increase in the equilibrium beta limit. On the contrary, for a vacuum configuration with the magnetic axis shifted outwards in the torus, even in the low beta regimes, the bootstrap current flows so as to reduce the rotational transform; therefore, there is an acceleration of the Shafranov shift increase as beta increases, leading to a decrease in the equilibrium beta limit. The pressure profiles and vertical field control methods influence the equilibrium beta limit through the location of the magnetic axis for finite beta. These characteristics are independent of both device parameters, such as magnetic field strength, and device size in the low collisional regime. (author)

  11. Evolution of the MHD sheet pinch

    International Nuclear Information System (INIS)

    Matthaeus, W.H.; Montgomery, D.

    1979-01-01

    A magnetohydrodynamic (MHD) problem of recurrent interest for both astrophysical and laboratory plasmas is the evolution of the unstable sheet pinch, a current sheet across which a dc magnetic field reverses sign. The evolution of such a sheet pinch is followed with a spectral-method, incompressible, two-dimensional, MHD turbulence code. Spectral diagnostics are employed, as are contour plots of vector potential (magnetic field lines), electric current density, and velocity stream function (velocity streamlines). The nonlinear effect which seems most important is seen to be current filamentation: the concentration of the current density onto sets of small measure near a mgnetic X point. A great deal of turbulence is apparent in the current distribution, which, for high Reynolds numbers, requires large spatial grids (greater than or equal to (64) 2 ). 11 figures, 1 table

  12. An analysis of plasma ion toroidal rotation during large amplitude MHD activity in JET

    International Nuclear Information System (INIS)

    Snipes, J.A.; Esch, H.P.L. de; Lazzaro, E.; Stork, D.; Hellermann, M. von; Galvao, R.; Hender, T.C.; Zasche, D.

    1989-01-01

    A detailed study of plasma ion toroidal rotation in JET during large amplitude MHD activity has revealed a strong viscous force that couples plasma ions to MHD modes. Depending on the MHD modes present, this force can couple across all of the plasma cross section, across only the central region, roughly within the q=1 surface, or across only the outer region outside the q=1.5 surface. The force acts to flatten the ion toroidal rotation frequency profile, measured by the JET active charge exchange spectroscopy diagnostic, across the coupled region of plasma. The frequency of rotation in this region agrees with the MHD oscillation frequency measured by magnetic pick-up coils at the wall. The strength of the force between the ions and modes becomes evident during high power NBI when the mode locks and drags the ion toroidal rotation frequency to zero, within the errors of the measurements. The present theories of plasma rotation either ignore MHD effects entirely, consider only moderate n toroidal field ripple, or low n ripple effects. (author) 7 refs., 3 figs

  13. NUMERICAL SIMULATION OF EXCITATION AND PROPAGATION OF HELIOSEISMIC MHD WAVES: EFFECTS OF INCLINED MAGNETIC FIELD

    International Nuclear Information System (INIS)

    Parchevsky, K. V.; Kosovichev, A. G.

    2009-01-01

    Investigation of propagation, conversion, and scattering of MHD waves in the Sun is very important for understanding the mechanisms of observed oscillations and waves in sunspots and active regions. We have developed a three-dimensional linear MHD numerical model to investigate the influence of the magnetic field on excitation and properties of the MHD waves. The results show that surface gravity waves (f-modes) are affected by the background magnetic field more than acoustic-type waves (p-modes). Comparison of our simulations with the time-distance helioseismology results from Solar and Heliospheric Observatory/MDI shows that the amplitude of travel time variations with azimuth around sunspots caused by the inclined magnetic field does not exceed 25% of the observed amplitude even for strong fields of 1400-1900 G. This can be an indication that other effects (e.g., background flows and nonuniform distribution of the magnetic field) can contribute to the observed azimuthal travel time variations. The azimuthal travel time variations caused by the wave interaction with the magnetic field are similar for simulated and observed travel times for strong fields of 1400-1900 G if Doppler velocities are taken at the height of 300 km above the photosphere where the plasma parameter β << 1. For the photospheric level the travel times are systematically smaller by approximately 0.12 minutes than for the height of 300 km above the photosphere for all studied ranges of the magnetic field strength and inclination angles. Numerical MHD wave modeling and new data from the HMI instrument of the Solar Dynamics Observatory will substantially advance our knowledge of the wave interaction with strong magnetic fields on the Sun and improve the local helioseismology diagnostics.

  14. Numerical Simulation of 3D Viscous MHD Flows

    National Research Council Canada - National Science Library

    Golovachov, Yurii P; Kurakin, Yurii A; Schmidt, Alexander A; Van Wie, David M

    2003-01-01

    .... Flows in hypersonic intakes are considered. Preliminary results showed that local MHD interaction in the inlet part of the intake model was the most effective for control over plasma flow field...

  15. Priority pollutant analysis of MHD-derived combustion products

    Science.gov (United States)

    Parks, Katherine D.

    An important factor in developing Magnetohydrodynamics (MHD) for commercial applications is environmental impact. Consequently, an effort was initiated to identify and quantify any possible undesirable minute chemical constituents in MHD waste streams, with special emphasis on the priority pollutant species. This paper discusses how priority pollutant analyses were used to accomplish the following goals at the University of Tennessee Space Institute (UTSI): comparison of the composition of solid combustion products collected from various locations along a prototypical MHD flow train during the firing of Illinois No. 6 and Montana Rosebud coals; comparison of solid waste products generated from MHD and conventional power plant technologies; and identification of a suitable disposal option for various MHD derived combustion products. Results from our ongoing research plans for gas phase sampling and analysis of priority pollutant volatiles, semi-volatiles, and metals are discussed.

  16. MHD intermediate shock discontinuities: Pt. 1

    International Nuclear Information System (INIS)

    Kennel, C.F.; Blandford, R.D.; Coppi, P.

    1989-01-01

    Recent numerical investigations have focused attention once more on the role of intermediate shocks in MHD. Four types of intermediate shock are identified using a graphical representation of the MHD Rankine-Hugoniot conditions. This same representation can be used to exhibit the close relationship of intermediate shocks to switch-on shocks and rotational discontinuities. The conditions under which intermediate discontinuities can be found are elucidated. The variations in velocity, pressure, entropy and magnetic-field jumps with upstream parameters in intermediate shocks are exhibited graphically. The evolutionary arguments traditionally advanced against intermediate shocks may fail because the equations of classical MHD are not strictly hyperbolic. (author)

  17. Experimental rigs for MHD studies

    International Nuclear Information System (INIS)

    Venkataramani, N.; Jayakumar, R.; Iyer, D.R.; Dixit, N.S.

    1976-01-01

    An MHD experimental rig is a miniature MHD installation consisting of basic equipments necessary for specific investigations. Some of the experimental rigs used in the investigations being carried out at the Bhabha Atomic Research Centre, Bombay (India) are dealt with. The experiments included diagnostics and evaluation of materials in seeded combustion plasmas and argon plasmas. The design specifications, schematics and some of the results of the investigations are also mentioned. (author)

  18. Promoter Hypermethylation of the EMP3 Gene in a Series of 229 Human Gliomas

    Directory of Open Access Journals (Sweden)

    Marta Mellai

    2013-01-01

    Full Text Available The epithelial membrane protein 3 (EMP3 is a candidate tumor suppressor gene in the critical region 19q13.3 for several solid tumors, including tumors of the nervous systems. The aim of this study was to investigate the EMP3 promoter hypermethylation status in a series of 229 astrocytic and oligodendroglial tumors and in 16 GBM cell lines. The analysis was performed by methylation-specific PCR and capillary electrophoresis. Furthermore, the EMP3 expression at protein level was evaluated by immunohistochemistry and Western blotting analysis. Associations of EMP3 hypermethylation with total 1p/19q codeletion, MGMT promoter hypermethylation, IDH1/IDH2 and TP53 mutations, and EGFR amplification were studied, as well as its prognostic significance. The EMP3 promoter hypermethylation has been found in 39.5% of gliomas. It prevailed in low-grade tumors, especially in gliomas with an oligodendroglial component, and in sGBMs upon pGBMs. In oligodendroglial tumors, it was strongly associated with both IDH1/IDH2 mutations and total 1p/19q codeletion and inversely with EGFR gene amplification. No association was found with MGMT hypermethylation and TP53 mutations. In the whole series, the EMP3 hypermethylation status correlated with 19q13.3 loss and lack of EMP3 expression at protein level. A favorable prognostic significance on overall survival of the EMP3 promoter hypermethylation was found in patients with oligodendroglial tumors.

  19. MHD Integrated Topping Cycle Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois {number sign}6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.

  20. Axisymmetric MHD stable sloshing ion distributions

    International Nuclear Information System (INIS)

    Berk, H.L.; Dominguez, N.; Roslyakov, G.V.

    1986-07-01

    The MHD stability of a sloshing ion distribution is investigated in a symmetric mirror cell. Fokker-Planck calculations show that stable configurations are possible for ion injection energies that are at least 150 times greater than the electron temperture. Special axial magnetic field profiles are suggested to optimize the favorable MHD properties

  1. A study of some recent advances in the concept and design of MHD generators

    International Nuclear Information System (INIS)

    Vakilian, M.

    1976-02-01

    Direct conversion of energy and high temperature working fluid making Magnetohydrodynamics (MHD) power plants potentially much more efficient than steam power stations. The study indicates an overall efficiency of 50% to 60%. This compares with most modern fossil-fuel plants at 40% efficiency. Advances in design and construction of experimental and commercial MHD plants developed in various countries are presented. Environmental effects and advantages of the MHD power plants over the more conventional fossil and nuclear plants are discussed

  2. Dynamics of nonlinear resonant slow MHD waves in twisted flux tubes

    Directory of Open Access Journals (Sweden)

    R. Erdélyi

    2002-01-01

    Full Text Available Nonlinear resonant magnetohydrodynamic (MHD waves are studied in weakly dissipative isotropic plasmas in cylindrical geometry. This geometry is suitable and is needed when one intends to study resonant MHD waves in magnetic flux tubes (e.g. for sunspots, coronal loops, solar plumes, solar wind, the magnetosphere, etc. The resonant behaviour of slow MHD waves is confined in a narrow dissipative layer. Using the method of simplified matched asymptotic expansions inside and outside of the narrow dissipative layer, we generalise the so-called connection formulae obtained in linear MHD for the Eulerian perturbation of the total pressure and for the normal component of the velocity. These connection formulae for resonant MHD waves across the dissipative layer play a similar role as the well-known Rankine-Hugoniot relations connecting solutions at both sides of MHD shock waves. The key results are the nonlinear connection formulae found in dissipative cylindrical MHD which are an important extension of their counterparts obtained in linear ideal MHD (Sakurai et al., 1991, linear dissipative MHD (Goossens et al., 1995; Erdélyi, 1997 and in nonlinear dissipative MHD derived in slab geometry (Ruderman et al., 1997. These generalised connection formulae enable us to connect solutions obtained at both sides of the dissipative layer without solving the MHD equations in the dissipative layer possibly saving a considerable amount of CPU-time when solving the full nonlinear resonant MHD problem.

  3. Alpha-Driven MHD and MHD-Induced Alpha Loss in TFTR DT Experiments

    Science.gov (United States)

    Chang, Zuoyang

    1996-11-01

    Theoretical calculation and numerical simulation indicate that there can be interesting interactions between alpha particles and MHD activity which can adversely affect the performance of a tokamak reactor (e.g., ITER). These interactions include alpha-driven MHD, like the toroidicity-induced-Alfven-eigenmode (TAE) and MHD induced alpha particle losses or redistribution. Both phenomena have been observed in recent TFTR DT experiments. Weak alpha-driven TAE activity was observed in a NBI-heated DT experiment characterized by high q0 ( >= 2) and low core magnetic shear. The TAE mode appears at ~30-100 ms after the neutral beam turning off approximately as predicted by theory. The mode has an amplitude measured by magnetic coils at the edge tildeB_p ~1 mG, frequency ~150-190 kHz and toroidal mode number ~2-3. It lasts only ~ 30-70 ms and has been seen only in DT discharges with fusion power level about 1.5-2.0 MW. Numerical calculation using NOVA-K code shows that this type of plasma has a big TAE gap. The calculated TAE frequency and mode number are close to the observation. (2) KBM-induced alpha particle loss^1. In some high-β, high fusion power DT experiments, enhanced alpha particle losses were observed to be correlated to the high frequency MHD modes with f ~100-200 kHz (the TAE frequency would be two-times higher) and n ~5-10. These modes are localized around the peak plasma pressure gradient and have ballooning characteristics. Alpha loss increases by 30-100% during the modes. Particle orbit simulations show the added loss results from wave-particle resonance. Linear instability analysis indicates that the plasma is unstable to the kinetic MHD ballooning modes (KBM) driven primarily by strong local pressure gradients. ----------------- ^1Z. Chang, et al, Phys. Rev. Lett. 76 (1996) 1071. In collaberation with R. Nazikian, G.-Y. Fu, S. Batha, R. Budny, L. Chen, D. Darrow, E. Fredrickson, R. Majeski, D. Mansfield, K. McGuire, G. Rewoldt, G. Taylor, R. White, K

  4. Experimental and theoretical studies of the effects of nonuniformities in equilibrium MHD generators

    International Nuclear Information System (INIS)

    Rosenbaum, M.; Shamma, S.E.; Louis, J.F.

    1980-01-01

    An experimental study of the effects of thermal and velocity nonuniformities is performed in an equilibrium plasma for a range of Hall parameters. An electrodeless MHD disk generator with radial flow is chosen as the ideal geometry for these experiments. By introducing equally spaced cold blades in the flow, it is possible to create well defined two-dimensional wake nonuniformities with strong variations of the plasma properties in the direction normal to the magnetic field and the flow. This type of nonuniformity is predicted to provide the strongest reduction of Hall coefficient and effective conductivity for high values of Hall parameter. This degradation is controlled by both the level of nonuniformities and the value of the ideal Hall parameter. The former is dependent upon the number of blades (root mean square deviation of the conductivity), and the latter is dependent upon the values of the magnetic field intensities. The results provide basic quantitative information about the effects of conductivity and velocity nonuniformities on the performance of equilibrium MHD generators over a wide range of Hall coefficients, between 2 and 7. Reduction formulae are established between the effective and ideal Hall parameters for different levels of nonuniformities intensities. Theoretical predictions are derived from a detailed two-dimensional electrodynamic analysis and a simplified engineering model based on a generalization of Rosa's layer model. These experiments validate the analytical studies and support the use of the theoretical layer models in describing the effect of boundary layers on the performance of linear generators

  5. Bifurcated equilibria in two-dimensional MHD with diamagnetic effects

    International Nuclear Information System (INIS)

    Ottaviani, M.; Tebaldi, C.

    1998-12-01

    In this work we analyzed the sequence of bifurcated equilibria in two-dimensional reduced magnetohydrodynamics. Diamagnetic effects are studied under the assumption of a constant equilibrium pressure gradient, not altered by the formation of the magnetic island. The formation of an island when the symmetric equilibrium becomes unstable is studied as a function of the tearing mode stability parameter Δ' and of the diamagnetic frequency, by employing fixed-points numerical techniques and an initial value code. At larger values of Δ' a tangent bifurcation takes place, above which no small island solutions exist. This bifurcation persists up to fairly large values of the diamagnetic frequency (of the order of one tenth of the Alfven frequency). The implications of this phenomenology for the intermittent MHD dynamics observed in tokamaks is discussed. (authors)

  6. Substorm effects in MHD and test particle simulations of magnetotail dynamics

    International Nuclear Information System (INIS)

    Birn, J.; Hesse, M.

    1998-01-01

    Recent magnetohydrodynamic simulations demonstrate that a global tail instability, initiated by localized breakdown of MHD, can cause plasmoid formation and ejection as well as dipolarization and the current diversion of the substorm current wedge. The connection between the reconnection process and the current wedge signatures is provided by earthward flow from the reconnection site. Its braking and diversion in the inner magnetosphere causes dipolarization and the magnetic field distortions of the current wedge. The authors demonstrate the characteristic properties of this process and the current systems involved. The strong localized electric field associated with the flow burst and the dipolarization is also the cause of particle acceleration and energetic particle injections. Test particle simulations of orbits in the MHD fields yield results that are quite consistent with observed injection signatures

  7. Hall effects on MHD flow past an accelerated plate

    International Nuclear Information System (INIS)

    Soundalgekar, V.M.; Ravi, S.; Hiremath, S.B.

    1980-01-01

    An exact solution of the MHD flow of an incompressible, electrically conducting, viscous fluid past a uniformly accelerated plate is presented. The velocity profiles are shown graphically and the numerical values of axial and transverse components of skin friction are tabulated. At high values of the Hall parameter, ωtau, the velocity is found to be oscillatory near the plate. (author)

  8. Achievement report on contract research. Large-scale project - Results of 1st-phase research and development of MHD power generation system; Plant system no hyoka. Ogata project dai 1 ki MHD hatsuden system kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1976-03-01

    Described in detail involving the results of component development, assessment, and the indication of problems are the power generation channel, superconductive magnets and a helium refrigeration and liquefaction unit, seeds collector, heat exchanger, combustor, etc. Described involving the result and effect of power generation system research and development and the indication of problems is the research on Mark V and Mark VI operation tests. Described in relation to thermal performance calculation, economic effectiveness calculation, and environmental conservation involving an MHD (magnetohydrodynamic) power plant are the combustion of heavy oil, combustion of natural gas, plant having a 1,000MW power generator as its base load, control of NOx and sulfur in MHD power generation, etc. As for planning for the next stage, the configuration of a 10MW MHD power generation plant, its equipment, construction cost, and preliminary element research, etc., are described. Furthermore, propositions are presented concerning future plans and the prospect of commercial MHD power generators, technological ripple effects due to MHD power generation research and development, and research and development in the future. (NEDO)

  9. sae is essential for expression of the staphylococcal adhesins Eap and Emp.

    Science.gov (United States)

    Harraghy, Niamh; Kormanec, Jan; Wolz, Christiane; Homerova, Dagmar; Goerke, Christiane; Ohlsen, Knut; Qazi, Saara; Hill, Philip; Herrmann, Mathias

    2005-06-01

    Eap and Emp are two Staphylococcus aureus adhesins initially described as extracellular matrix binding proteins. Eap has since emerged as being important in adherence to and invasion of eukaryotic cells, as well as being described as an immunomodulator and virulence factor in chronic infections. This paper describes the mapping of the transcription start point of the eap and emp promoters. Moreover, using reporter-gene assays and real-time PCR in defined regulatory mutants, environmental conditions and global regulators affecting expression of eap and emp were investigated. Marked differences were found in expression of eap and emp between strain Newman and the 8325 derivatives SH1000 and 8325-4. Moreover, both genes were repressed in the presence of glucose. Analysis of expression of both genes in various regulatory mutants revealed that sarA and agr were involved in their regulation, but the data suggested that there were additional regulators of both genes. In a sae mutant, expression of both genes was severely repressed. sae expression was also reduced in the presence of glucose, suggesting that repression of eap and emp in glucose-containing medium may, in part, be a consequence of a decrease in expression of sae.

  10. Análisis semiótico en secuencias de interacción empáticas y no empáticas: un estudio microgenético

    Directory of Open Access Journals (Sweden)

    Pablo Fossa

    Full Text Available Resumen Este estudio tuvo por objetivo explorar y describir el proceso de regulación dialógica en interacciones conversacionales. Se registraron en video treinta díadas de estudiantes desconocidos entre sí en interacciones que tuvieron una manipulación orientada a generar una situación empática o bien no-empática. Se seleccionaron cuatro segmentos de conversación, dos por cada tipo de interacción. El texto fue analizado con un protocolo de análisis semiótico basado en el modelo de análisis propuesto por (Molina, 2007. Los resultados muestran que las interacciones empáticas se caracterizan por un proceso de coconstrucción de significados, con una adecuada administración de la tensión y una identificación con el signo lingüístico. Por otra parte, las interacciones no empáticas se caracterizan por la emergencia de signos lingüísticos que no continúan la secuencia de construcción de significados; con una alta tensión dialógica, y una estrategia de distanciamiento o abandono del campo de significado.

  11. MHD equilibrium and stability in heliotron plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ichiguchi, Katsuji [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1999-09-01

    Recent topics in the theoretical magnetohydrodynamic (MHD) analysis in the heliotron configuration are overviewed. Particularly, properties of three-dimensional equilibria, stability boundary of the interchange mode, effects of the net toroidal current including the bootstrap current and the ballooning mode stability are focused. (author)

  12. Cryogenic aspects of the experience in operating the U-25 superconducting MHD magnet in conjunction with the MHD generator

    International Nuclear Information System (INIS)

    Niemann, R.C.; Mataya, K.F.; Smith, R.P.; McWilliams, D.A.; Borden, R.; Streeter, M.H.; Wickson, R.; Privalov, N.P.

    1978-01-01

    In order to facilitate the rapid development of MHD technology for the generation of electrical energy, the U.S. and U.S.S.R. are jointly conducting research within the framework of the Program of Scientific and Technical Cooperation. The Institute for High Temperature (IVTAN) of the U.S.S.R. has designed and fabricated a special MHD facility which uses as its base much of the equipment of the existing U-25 Facility. The new MHD fow train consisting of a combustor, magnet, channel, and diffuser is named U-25B. The U.S. has provided a superconducting magnet system for the U-25B MHD Facility. As a result of these joint efforts, a unique and broad range of experimental test conditions similar to those that will exist in operation of commercial MHD generators has been created. The United States Superconducting Magnet System (U.S. SCMS) was designed, fabricated, and delivered to the U-25B Facility by the Argonne National Laboratory (ANL) under the sponsorship of the U.S. Department of Energy. The following description focuses on the cryogenic-related aspects of the magnet system commissioning and operation in the U.S.S.R

  13. The high beta tokamak-extended pulse magnetohydrodynamic mode control research program

    International Nuclear Information System (INIS)

    Maurer, D A; Bialek, J; Byrne, P J; De Bono, B; Levesque, J P; Li, B Q; Mauel, M E; Navratil, G A; Pedersen, T S; Rath, N; Shiraki, D

    2011-01-01

    The high beta tokamak-extended pulse (HBT-EP) magnetohydrodynamic (MHD) mode control research program is studying ITER relevant internal modular feedback control coil configurations and their impact on kink mode rigidity, advanced digital control algorithms and the effects of plasma rotation and three-dimensional magnetic fields on MHD mode stability. A new segmented adjustable conducting wall has been installed on the HBT-EP and is made up of 20 independent, movable, wall shell segments instrumented with three distinct sets of 40 saddle coils, totaling 120 in-vessel modular feedback control coils. Each internal coil set has been designed with varying toroidal angular coil coverage of 5, 10 and 15 0 , spanning the toroidal angle range of an ITER port plug based internal coil to test resistive wall mode (RWM) interaction and multimode MHD plasma response to such highly localized control fields. In addition, we have implemented 336 new poloidal and radial magnetic sensors to quantify the applied three-dimensional fields of our control coils along with the observed plasma response. This paper describes the design and implementation of the new control shell incorporating these control and sensor coils on the HBT-EP, and the research program plan on the upgraded HBT-EP to understand how best to optimize the use of modular feedback coils to control instability growth near the ideal wall stabilization limit, answer critical questions about the role of plasma rotation in active control of the RWM and the ferritic resistive wall mode, and to improve the performance of MHD control systems used in fusion experiments and future burning plasma systems.

  14. Emp is a component of the nuclear matrix of mammalian cells and undergoes dynamic rearrangements during cell division

    International Nuclear Information System (INIS)

    Bala, Shashi; Kumar, Ajay; Soni, Shivani; Sinha, Sudha; Hanspal, Manjit

    2006-01-01

    Emp, originally detected in erythroblastic islands, is expressed in numerous cell types and tissues suggesting a functionality not limited to hematopoiesis. To study the function of Emp in non-hematopoietic cells, an epitope-tagged recombinant human Emp was expressed in HEK cells. Preliminary studies revealed that Emp partitioned into both the nuclear and Triton X-100-insoluble cytoskeletal fractions in approximately a 4:1 ratio. In this study, we report investigations of Emp in the nucleus. Sequential extractions of interphase nuclei showed that recombinant Emp was present predominantly in the nuclear matrix. Immunofluorescence microscopy showed that Emp was present in typical nuclear speckles enriched with the spliceosome assembly factor SC35 and partially co-localized with actin staining. Coimmunoprecipitation and GST-pull-down assays confirmed the apparent close association of Emp with nuclear actin. During mitosis, Emp was detected at the mitotic spindle/spindle poles, as well as in the contractile ring during cytokinesis. These results suggest that Emp undergoes dynamic rearrangements within the nuclear architecture that are correlated with cell division

  15. Gel shift analysis of the empA promoter region in Vibrio anguillarum

    Directory of Open Access Journals (Sweden)

    Denkin Steven M

    2004-10-01

    Full Text Available Abstract Background The induction of metalloprotease encoded by empA in Vibrio anguillarum occurs at high cell density in salmon intestinal mucus. Previously we have shown that there are significant differences in empA expression in two strains of V. anguillarum, M93Sm and NB10. It is hypothesized that differences in empA regulation are due to differences in binding of regulatory elements. Results Two strains of V. anguillarum, M93Sm and NB10, were examined and compared for the presence of DNA regulatory proteins that bind to and control the empA promoter region. Gel mobility shift assays, using a digoxigenin (DIG-labeled oligomer containing a lux box-like element and the promoter for empA, were done to demonstrate the presence of a DNA-binding protein. Protein extracts from NB10 cells incubated in Luria Bertani broth + 2% NaCl (LB20, nine salts solution + 200 μg/ml mucus (NSSM, 3M (marine minimal medium, or NSS resulted in a gel mobility shift. No gel mobility shift was seen when protein extracts from either LB20- or NSSM-grown M93Sm cells were mixed with the DIG-labeled empA oligomer. The azocasein assay detected protease activity in all incubation conditions for NB10 culture supernatants. In contrast, protease activity was detected in M93Sm culture supernatants only when incubated in NSSM. Since the luxR homologue in V. anguillarum, vanT, has been cloned, sequenced, and shown to be required for protease activity, we wanted to determine if vanT mutants of NB10 exhibit the same gel shift observed in the wild-type. Site-directed mutagenesis was used to create vanT mutants in V. anguillarum M93Sm and NB10 to test whether VanT is involved with the gel mobility shift. Both vanT mutants, M02 and NB02, did not produce protease activity in any conditions. However, protein extracts from NB02 incubated in each condition still exhibited a gel shift when mixed with the DIG-labeled empA oligomer. Conclusions The data demonstrate that protein extracts of V

  16. Flow predictions for MHD channels with an approximation for three-dimensional effects

    International Nuclear Information System (INIS)

    Blottner, F.G.

    1978-01-01

    A finite-difference procedure has been formulated for predicting the flow properties across channels. A quasi-two-dimensional approach has been developed which allows the three-dimensional channel effects to be taken into account. Comparison of the numerical solutions with experimental results show that this approach is a reasonable approximation for MHD flow conditions if there is not significant merging of the wall boundary layers. The resulting code provides a technique to obtain the flow details in the symmetry plane of the channel and requires only a small amount of computer time

  17. Role of MHD activity in LH-assisted discharges in the PBX-M tokamak

    International Nuclear Information System (INIS)

    Talvard, M.; Bell, R.E.; Bernabei, S.; Kaye, S.; Okabayashi, M.; Sesnic, S.; von Goeler, S.

    1995-01-01

    A data base for the 1993 run period of PBX-M has been documented (i) to investigate whether it was possible to forecast the development of MHD instabilities often observed in LH assisted discharges and (ii) to detail the origin, the nature and the effects of those instabilities. The deposition radius of the RF current, the plasma internal inductance and the LH power are used to separate MHD active and quiescent regimes prior the MHD onset. 1/1, 2/1, 3/1 global modes driven by the m = 2, n = 1 component are observed in discharges with LHCD. The destabilization is attributed to an increase of the current density gradient within the q = 2 surface. MHD fluctuations reduce the soft x-ray and hard x-ray intensities mainly around the RF current deposition radius. Minor disruptions with large inversion radii and mode locking are analyzed. Pi possible precursor to the MHD is evidenced on the hard x-ray horizontal profiles. A resonance between fast trapped electrons and turbulent waves present in the background plasma is proposed to support the observations

  18. Problems in nonlinear resistive MHD

    International Nuclear Information System (INIS)

    Turnbull, A.D.; Strait, E.J.; La Haye, R.J.; Chu, M.S.; Miller, R.L.

    1998-01-01

    Two experimentally relevant problems can relatively easily be tackled by nonlinear MHD codes. Both problems require plasma rotation in addition to the nonlinear mode coupling and full geometry already incorporated into the codes, but no additional physics seems to be crucial. These problems discussed here are: (1) nonlinear coupling and interaction of multiple MHD modes near the B limit and (2) nonlinear coupling of the m/n = 1/1 sawtooth mode with higher n gongs and development of seed islands outside q = 1

  19. Effects of electromagnetic radiation on morphology and TGF-β3 expression in mouse testicular tissue.

    Science.gov (United States)

    Luo, Yaning; Wang, Xiaowu; Chen, Yongbin; Xu, Shenglong; Ding, Guirong; Shi, Changhong

    2013-08-09

    Exposure to electromagnetic pulses in certain doses may lead to increase in the permeability of the blood testes barrier (BTB) in mice, which in turn affects spermatogenesis, penetration and spermiation. TGF-β3 is a key molecule involved in BTB permeability via regulation of tight junction proteins, and it participates in regulating spermatogenesis, synthesis of steroids and production of the extracellular matrix in testicular tissue. Therefore, it is hypothesized that TGF-β3 plays important roles in electromagnetic pulse (EMP)-induced changes in BTB permeability. In the present study, we carried out whole-body irradiation on mice using EMP of different intensities. No obvious pathological changes or significant increase in apoptosis was detected in testicular tissues after exposure to 100 and 200 pulses of intensity 200kV/m; however, with 400 pulses we observed the degeneration and shrinkage of testicular tissues along with a significant increase in apoptotic rate. Moreover, in the 100- and 200-EMP groups, a non-significant increase in TGF-β3 mRNA and protein expression was observed, whereas in the 400-EMP group a significant increase was observed (P<0.05). These results indicate that increase in the apoptotic rate of testicular tissues and increase in TGF-β3 expression may be one of the mechanisms for EMP-induced increase in BTB permeability in mice. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. MHD power plants - a reality of the 80's

    International Nuclear Information System (INIS)

    Pishchikov, S.

    1981-01-01

    A 300 MW MHD generator and a conventional turbogenerator of the same capacity will be used for the first MHD power block assembly projected in the USSR. The power plant's own consumption will not exceed 12% and the availability will be approximately 50%. Compared with a conventional power generating unit of a capacity of 500 MW the projected unit will provide fuel savings of at least 23%. The project is based on almost seven years long experience with the U-25 experimental MHD facility. Similar to the U-25, the MHD power plant projected will be fired with natural gas. (B.S.)

  1. MHD power plants - a reality of the 80's

    Energy Technology Data Exchange (ETDEWEB)

    Pishchikov, S

    1981-02-01

    A 300 MW MHD generator and a conventional turbogenerator of the same capacity will be used for the first MHD power block assembly projected in the USSR. The power plant's own consumption will not exceed 12% and the availability will be approximately 50%. Compared with a conventional power generating unit of a capacity of 500 MW the projected unit will provide fuel savings of at least 23%. The project is based on almost seven years long experience with the U-25 experimental MHD facility. Similar to the U-25, the MHD power plant projected will be fired with natural gas.

  2. Mesothelioma and other lung disease in taconite miners; the uncertain role of non-asbestiform EMP.

    Science.gov (United States)

    Mandel, Jeffrey H; Odo, Nnaemeka U

    2018-04-10

    The purpose of this paper was to assess the role of non-asbestiform amphibole EMPs in the etiology of mesotheliomas and other lung disease in taconite (iron ore) miners. Increased mesothelioma rates have been described in Minnesota taconite workers since the late 1990s. Currently, over 100 cases have been reported by the Minnesota Department of Health within the complete cohort of miners in Minnesota. Geologic sampling has indicated that only the eastern part of the iron range contains non-asbestiform amphibole elongate mineral particles (EMPs), in close proximity to the ore. This type of EMP has been less studied and also exists in talc and gold mining. A series of investigations into the state's taconite industry have been recently completed. Results from a cohort mortality study indicated an SMR of 2.77 (95% CI = 1.87-3.96) for mesothelioma. In a case-control study, the odds ratio for mesothelioma for high vs. low EMP exposure was 2.25 (5% CI = 1.13-4.5) but EMPs in this study were counted by phase contrast microscopy. Odds ratios were not elevated in mines located in the eastern part of the Mesabi iron range. The overall findings suggest that mesothelioma in taconite miners is related to EMP exposure. Because of the way EMPs were counted, results from these studies cannot allow a firm conclusion about the association between EMP exposure and the reported excess mesothelioma. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Numerical analysis of liquid metal MHD flows through circular pipes based on a fully developed modeling

    International Nuclear Information System (INIS)

    Zhang, Xiujie; Pan, Chuanjie; Xu, Zengyu

    2013-01-01

    Highlights: ► 2D MHD code based on a fully developed modeling is developed and validated by Samad analytical results. ► The results of MHD effect of liquid metal through circular pipes at high Hartmann numbers are given. ► M type velocity profile is observed for MHD circular pipe flow at high wall conductance ratio condition. ► Non-uniform wall electrical conductivity leads to high jet velocity in Robert layers. -- Abstract: Magnetohydrodynamics (MHD) laminar flows through circular pipes are studied in this paper by numerical simulation under the conditions of Hartmann numbers from 18 to 10000. The code is developed based on a fully developed modeling and validated by Samad's analytical solution and Chang's asymptotic results. After the code validation, numerical simulation is extended to high Hartmann number for MHD circular pipe flows with conducting walls, and numerical results such as velocity distribution and MHD pressure gradient are obtained. Typical M-type velocity is observed but there is not such a big velocity jet as that of MHD rectangular duct flows even under the conditions of high Hartmann numbers and big wall conductance ratio. The over speed region in Robert layers becomes smaller when Hartmann numbers increase. When Hartmann number is fixed and wall conductance ratios change, the dimensionless velocity is through one point which is in agreement with Samad's results, the locus of maximum value of velocity jet is same and effects of wall conductance ratio only on the maximum value of velocity jet. In case of Robert walls are treated as insulating and Hartmann walls as conducting for circular pipe MHD flows, there is big velocity jet like as MHD rectangular duct flows of Hunt's case 2

  4. Electromagnetic-implosion generation of pulsed high energy density plasma

    International Nuclear Information System (INIS)

    Baker, W.L.; Broderick, N.F.; Degnan, J.H.; Hussey, T.W.; Kiuttu, G.F.; Kloc, D.A.; Reinovsky, R.E.

    1983-01-01

    This chapter reports on the experimental and theoretical investigation of the generation of pulsed high-energy-density plasmas by electromagnetic implosion of cylindrical foils (i.e., imploding liners or hollow Z-pinches) at the Air Force Weapons Laboratory. Presents a comparison of experimental data with one-dimensional MHD and two-dimensional calculations. Points out that the study is distinct from other imploding liner efforts in that the approach is to produce a hot, dense plasma from the imploded liner itself, rather than to compress a magnetic-field-performed plasma mixture. The goal is to produce an intense laboratory pulsed X-ray source

  5. The Statistical Mechanics of Ideal MHD Turbulence

    Science.gov (United States)

    Shebalin, John V.

    2003-01-01

    Turbulence is a universal, nonlinear phenomenon found in all energetic fluid and plasma motion. In particular. understanding magneto hydrodynamic (MHD) turbulence and incorporating its effects in the computation and prediction of the flow of ionized gases in space, for example, are great challenges that must be met if such computations and predictions are to be meaningful. Although a general solution to the "problem of turbulence" does not exist in closed form, numerical integrations allow us to explore the phase space of solutions for both ideal and dissipative flows. For homogeneous, incompressible turbulence, Fourier methods are appropriate, and phase space is defined by the Fourier coefficients of the physical fields. In the case of ideal MHD flows, a fairly robust statistical mechanics has been developed, in which the symmetry and ergodic properties of phase space is understood. A discussion of these properties will illuminate our principal discovery: Coherent structure and randomness co-exist in ideal MHD turbulence. For dissipative flows, as opposed to ideal flows, progress beyond the dimensional analysis of Kolmogorov has been difficult. Here, some possible future directions that draw on the ideal results will also be discussed. Our conclusion will be that while ideal turbulence is now well understood, real turbulence still presents great challenges.

  6. Results from a large-scale MHD propulsion experiment

    International Nuclear Information System (INIS)

    Petrick, M.; Libera, J.; Bouillard, J.X.; Pierson, E.S.; Hill, D.

    1992-01-01

    This paper reports on magnetohydrodynamic (MHD) thrusters which have long been recognized as potentially attractive candidates for ship propulsion because such systems eliminate the conventional rotating drive components. The MHD thruster is essentially an electromagnet (EM) pump operating in seawater. An electrical current is passed directly through the seawater and interacts with an applied magnetic field; the interaction of the magnetic field and the electrode current in the seawater results in a Lorentz force acting on the water, and the reaction to this force propels the vessel forward. The concept of EM propulsion has been examined periodically during the past 35 years as an alternative method of propulsion for surface ships and submersibles. The conclusions reached in early studies were that MHD thrusters restricted to fields of 2T (the state-of-the-art at that time) were impractical and very inefficient. With the evolution of superconducting magnet technology, later studies investigated the performance of MHD thrusters with much higher magnetic field strengths and concluded that at higher fields (>6 T) practical MHD propulsion systems appear possible

  7. Development, characterization and evaluation of materials for open cycle MHD. Quarterly report, June 1979

    International Nuclear Information System (INIS)

    Bates, J.L.; Marchant, D.D.

    1979-10-01

    The objectives of this program are to develop, test, characterize, and evaluate materials for open-cycle, coal-fired MHD power generators. The specific immediate goals emphasize electrode and insulator materials, including: (1) testing and evaluation of the enhanced effects of alkali seed on materials in a dc electric field; (2) development and testing of improved electrodes and insulators with controlled microstructures, compositions and properties; and (3) characterization and evaluation of materials relating to both the US MHD Program and the US-USSR Cooperative Program for MHD power generators. Progress is reported

  8. Global and kinetic MHD simulation by the Gpic-MHD code

    International Nuclear Information System (INIS)

    Naitou, Hiroshi; Yamada, Yusuke; Kajiwara, Kenji; Lee, Wei-li; Tokuda, Shinji; Yagi, Masatoshi

    2011-01-01

    In order to implement large-scale and high-beta tokamak simulation, a new algorithm of the electromagnetic gyrokinetic PIC (particle-in-cell) code was proposed and installed on the Gpic-MHD code [Gyrokinetic PIC code for magnetohydrodynamic (MHD) simulation]. In the new algorithm, the vortex equation and the generalized ohm's law along the magnetic field are derived from the basic equations of the gyrokinetic Vlasov, Poisson, and Ampere system and are used to describe the spatio-temporal evolution of the field quantities of the electrostatic potential φ and the longitudinal component of the vector potential A z . Particle information is mainly used to estimate second order moments in the generalized ohm's law. Because the lower order moments of the charge density and the longitudinal current density are not used explicitly to determine φ and A z , the numerical noise induced by the discreteness of particle quantities reduces drastically. Another advantage of the algorithm is that the longitudinal induced electric field, E Tz =-∂A z /∂t, is explicitly estimated by the generalized ohm's law and used in the equations of motion. The particle velocities along the magnetic field are used (v z -formulation) instead of generalized momentums (p z -formulation), hence there is no problem of 'cancellation', which appear when estimating A z from the Ampere's law in the p z -formulation. The successful simulation of the collisionless internal kink mode by new Gpic-MHD with the realistic values of the large-scale and high-beta, revealed the usefulness of the new algorithm. (author)

  9. Report on results of contract research. 'Research on MHD generation system'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1982-03-01

    'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1981 reported. This year, technological reexamination was conducted for a 2,000 MWt commercial MHD generation plant, with evaluation carried out on the cost performance including the construction and operation cost. In addition, for the purpose of intermediate R and D towards the practicability, examination was also conducted on a system structure, concrete specifications of component element, cost of R and D including operation expenses for example, concerning an 100 MWt class experimental plant and a 500 MWt class plant. In the investigation of the overseas trend, information was summarized in detail on the experimental devices, combustors, generation channels, electrode materials, electrode phenomena, theoretical analyses, seeds, slag, component equipment, instrumental technologies, conceptual designs of generation plant, commercial plant, etc., in Soviet Union, China, Holland, India and EPRI, on the basis of the materials from the 19th MHD symposium held in UTSI and from the coal MHD specialist conference held in Sydney. (NEDO)

  10. Effect of non-uniform Hall parameter on the electrode voltage drop in Faraday-type combustion MHD generators

    International Nuclear Information System (INIS)

    Gupta, G.P.; Rohatgi, V.K.

    1982-01-01

    Following a simplified approach, an expression is derived for the gas-dynamic voltage drop in a finitely segmented Faraday-type combustion MHD generator, taking into account the non-uniform Hall parameter across the channel. Combining the electrical sheath voltage drop, discussed briefly, with the gas-dynamic voltage drop, the effect of a non-uniform Hall parameter on the electrode voltage drop is studied using the theoretical and experimental input parameters of the Indian MHD channel test. The condition for the validity of the usual assumption of uniform Hall parameter across the channel is pointed out. Analysis of the measured electrode voltage drop predicts the real gas conductivity in the core to be in the range of 60 to 75 per cent of the theoretically calculated core conductivity. (author)

  11. Magnetic levitation and MHD propulsion

    Science.gov (United States)

    Tixador, P.

    1994-04-01

    Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried out in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ...) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. Depuis quelques années nous assistons à un redémarrage de programmes concernant la lévitation et la propulsion supraconductrices. Différents systèmes supraconducteurs de lévitation et de propulsion seront décrits en examinant plus particulièrement l'aspect électromagnétique. Quelques programmes à travers le monde seront abordés. Les trains à sustentation magnétique pourraient constituer un nouveau mode de transport terrestre à vitesse élevée (500 km/h) pour le 21^e siècle. Les japonais n'ont cessé de s'intéresser à ce système avec bobine supraconductrice. Ils envisagent un stade préindustriel avec la construction d'une ligne de 43 km. En 1991 un programme américain pour une durée de six ans a été lancé pour évaluer les performances des systèmes à lévitation pour le transport aux Etats Unis. La MHD (Magnéto- Hydro-Dynamique) présente des avantages intéressants pour la propulsion navale et un regain d'intérêt apparaît à l'heure actuelle. Le japon se situe là encore à la pointe des d

  12. Kemasan Menarik dan Internet Marketing untuk Meningkatkan Nilai Jual Emping Garut sebagai Produk Unggulan Kabupaten Sragen

    Directory of Open Access Journals (Sweden)

    Sari Purnavita

    2018-03-01

    Full Text Available Tanaman garut termasuk dalam jenis umbi-umbian yang banyak ditanam oleh masyarakat yang tinggal di Kecamatan Gesi, Kabupaten Sragen. Di Kabupaten Sragen terdapat beberapa industri rumah tangga emping garut, dua di antaranya yang memiliki motivasi sangat besar untuk berkembang adalah UKM emping garut “Sumber Rejeki” dan UKM emping garut “Fadilah”. Permasalahan kedua UKM adalah keterbatasan inovasi rasa emping garut, kemasan sangat sederhana, dan sistem pemasaran masih tradisional sehingga sehingga omzet penjualan dan nilai jual produk masih rendah. Untuk meningkatkan omzet penjualan dapat dilakukan dengan perbaikan inovasi dan teknologi pengemasan, teknologi seasoning dengan bumbu tabur, dan memperluas pemasaran dengan media internet. Produk emping garut yang dikemas secara menarik, inovasi produk emping garut aneka rasa, dan pemasaran dengan media internet melalui blogspot dapat menenbus pemasaran secara luas baik di toko-toko besar, harga jual produk meningkat 50%,dan omzet penjualan meningkat 100%.

  13. PHYSICAL PERFORMANCE AND BODY COMPOSITION IN MAINTENANCE HEMODIALYSIS (MHD PATIENTS

    Directory of Open Access Journals (Sweden)

    M Zhang

    2012-06-01

    Conclusions: These findings indicate that adult MHD pts had a higher % body fat. Measures of physical performance were markedly reduced in MHD pts as compared to Normals. Physical performance in MHD, measured especially by 6-MW, correlated negatively with some measures of body composition, particularly with LBMI.

  14. Free-boundary perturbed MHD equilibria

    International Nuclear Information System (INIS)

    Nührenberg, C

    2012-01-01

    The concept of perturbed ideal MHD equilibria [Boozer A H and Nuhrenberg C 2006 Phys. Plasmas 13 102501] is employed to study the influence of external error-fields and of small plasma-pressure changes on toroidal plasma equilibria. In tokamak and stellarator free-boundary calculations, benchmarks were successful of the perturbed-equilibrium version of the CAS3D stability code [Nührenberg C et al. 2009 Phys. Rev. Lett. 102 235001] with the ideal MHD equilibrium code NEMEC [Hirshman S P et al. 1986 Comput. Phys. Commun. 43 143].

  15. An MHD Dynamo Experiment.

    Science.gov (United States)

    O'Connell, R.; Forest, C. B.; Plard, F.; Kendrick, R.; Lovell, T.; Thomas, M.; Bonazza, R.; Jensen, T.; Politzer, P.; Gerritsen, W.; McDowell, M.

    1997-11-01

    A MHD experiment is being constructed which will have the possibility of showing dynamo action: the self--generation of currents from fluid motion. The design allows sufficient experimental flexibility and diagnostic access to study a variety of issues central to dynamo theory, including mean--field electrodynamics and saturation (backreaction physics). Initially, helical flows required for dynamo action will be driven by propellers embedded in liquid sodium. The flow fields will first be measured using laser doppler velocimetry in a water experiment with an identical fluid Reynolds number. The magnetic field evolution will then be predicted using a MHD code, replacing the water with sodium; if growing magnetic fields are found, the experiment will be repeated with sodium.

  16. A hybrid LLR-MHD model of kink perturbations in EXTRAP

    International Nuclear Information System (INIS)

    Lehnert, B.

    1987-07-01

    In high-beta systems, such as Extrap and other Z-pinch configurations, kinetic large Larmor radius (LLR) phenomena introduce strong phase-mixing and dispersive effects and a corresponding 'kinetic damping' which cannot be treated in terms of MHD theory. In this paper a first attempt is made to include these effects by proposing a hybrid LLR-MHD model in which the kinetic phenomena enter as constraints on the possible forms of the plasma perturbations. The latter then become restricted to a limited class which can be treated in terms of MHD theory. The present model does not claim to produce stability conditions which are exact in all details, but should merely provide a picture of the general relationship between the basic plasma parameters in a state of marginal stability. For kink perturbations in Extrap stability relations have thus been obtained between the pinch and conductor currents, the pinch radius and the axial conductor distance, and the number of contained ion Larmor radii. These relations appear to be consistent with so far obtained experimental data. A short discussion on the effects of a superimposed axial magnetic field has been included. At this stage only experiments can verify whether or not the present simple model becomes relevant to Extrap stability. (author)

  17. Radiation heat transfer within an open-cycle MHD generator channel

    Science.gov (United States)

    Delil, A. A. M.

    1983-05-01

    Radiation heat transfer in an MHD generator was modeled using the Sparrow and Cess model for radiation in an emitting, absorbing and scattering medium. The resulting general equations can be considerably reduced by introducing simplifying approximations for the channel and MHD gas properties. The simplifications lead to an engineering model, which is very useful for one-dimensional channel flow approximation. The model can estimate thermo-optical MHD gas properties, which can be substituted in the energy equation. The model considers the contribution of solid particles in the MHD gas to radiation heat transfer, considerable in coal-fired closed cycle MHD generators. The modeling is applicable also for other types of flow at elevated temperatures, where radiation heat transfer is an important quantity.

  18. Starlite figures of merit for tokamak current drive - economic analysis of pulsed and steady state power plants with various engineering and physics performance parameters

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1995-09-01

    The physics efficiency of current drive (γ B ∝ n e I o R o /P CD ), including the bootstrap effect, needs to exceed certain goals in order to provide economical steady state operation compared to pulsed power plants. The goal for γ B depends not only on engineering performance of the current drive system, but also on normalized beta and the effective safety factor of the achievable MHD equilibrium

  19. STARLITE figures of merit for tokamak current drive -- Economic analysis of pulsed and steady state power plants with various engineering and physics performance parameters

    International Nuclear Information System (INIS)

    Ehst, D.A.; Jardin, S.; Kessel, C.

    1995-10-01

    The physics efficiency of current drive (γ B ∝ n e I 0 R 0 /P CD ), including the bootstrap effect, needs to exceed certain goals in order to provide economical steady state operation compared to pulsed power plants. The goal for γ B depends not only on engineering performance of the current drive system, but also on normalized beta and the effective safety factor of the achievable MHD equilibrium

  20. Statistical Theory of the Ideal MHD Geodynamo

    Science.gov (United States)

    Shebalin, J. V.

    2012-01-01

    A statistical theory of geodynamo action is developed, using a mathematical model of the geodynamo as a rotating outer core containing an ideal (i.e., no dissipation), incompressible, turbulent, convecting magnetofluid. On the concentric inner and outer spherical bounding surfaces the normal components of the velocity, magnetic field, vorticity and electric current are zero, as is the temperature fluctuation. This allows the use of a set of Galerkin expansion functions that are common to both velocity and magnetic field, as well as vorticity, current and the temperature fluctuation. The resulting dynamical system, based on the Boussinesq form of the magnetohydrodynamic (MHD) equations, represents MHD turbulence in a spherical domain. These basic equations (minus the temperature equation) and boundary conditions have been used previously in numerical simulations of forced, decaying MHD turbulence inside a sphere [1,2]. Here, the ideal case is studied through statistical analysis and leads to a prediction that an ideal coherent structure will be found in the form of a large-scale quasistationary magnetic field that results from broken ergodicity, an effect that has been previously studied both analytically and numerically for homogeneous MHD turbulence [3,4]. The axial dipole component becomes prominent when there is a relatively large magnetic helicity (proportional to the global correlation of magnetic vector potential and magnetic field) and a stationary, nonzero cross helicity (proportional to the global correlation of velocity and magnetic field). The expected angle of the dipole moment vector with respect to the rotation axis is found to decrease to a minimum as the average cross helicity increases for a fixed value of magnetic helicity and then to increase again when average cross helicity approaches its maximum possible value. Only a relatively small value of cross helicity is needed to produce a dipole moment vector that is aligned at approx.10deg with the

  1. Effects of stochastic field lines on the pressure driven MHD instabilities in the Large Helical Device

    Science.gov (United States)

    Ohdachi, Satoshi; Watanabe, Kiyomasa; Sakakibara, Satoru; Suzuki, Yasuhiro; Tsuchiya, Hayato; Ming, Tingfeng; Du, Xiaodi; LHD Expriment Group Team

    2014-10-01

    In the Large Helical Device (LHD), the plasma is surrounded by the so-called magnetic stochastic region, where the Kolmogorov length of the magnetic field lines is very short, from several tens of meters and to thousands meters. Finite pressure gradient are formed in this region and MHD instabilities localized in this region is observed since the edge region of the LHD is always unstable against the pressure driven mode. Therefore, the saturation level of the instabilities is the key issue in order to evaluate the risk of this kind of MHD instabilities. The saturation level depends on the pressure gradient and on the magnetic Reynolds number; there results are similar to the MHD mode in the closed magnetic surface region. The saturation level in the stochastic region is affected also by the stocasticity itself. Parameter dependence of the saturation level of the MHD activities in the region is discussed in detail. It is supported by NIFS budget code ULPP021, 028 and is also partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research 26249144, by the JSPS-NRF-NSFC A3 Foresight Program NSFC: No. 11261140328.

  2. MHD power generation research, development and engineering. Quarterly progress report, October-December 1979

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    Progress is reported on the following tasks: characterization of coal for open-cycle MHD power generation systems; compressive creep and strength studies of MHD preheater materials; preparation of coals for utilization in direct coal-fired MHD generation; characterization of volatile matter in coal; MHD materials evaluation; operability of the Moderate Temperature Slag Flow Facility; slag-seed equilibria and separations related to the MHD system; thermionic emission of coal and electrode materials; MHD instrumentation, consolidated inversion simulator, and data acquisition; combined MHD-steam plant cycle analysis and control; and slag physical properties - electrical and thermal conductivity. (WHK)

  3. Magnetic evaluation of hydrogen pressures changes on MHD fluctuations in IR-T1 tokamak plasma

    Science.gov (United States)

    Alipour, Ramin; Ghanbari, Mohamad R.

    2018-04-01

    Identification of tokamak plasma parameters and investigation on the effects of each parameter on the plasma characteristics is important for the better understanding of magnetohydrodynamic (MHD) activities in the tokamak plasma. The effect of different hydrogen pressures of 1.9, 2.5 and 2.9 Torr on MHD fluctuations of the IR-T1 tokamak plasma was investigated by using of 12 Mirnov coils, singular value decomposition and wavelet analysis. The parameters such as plasma current, loop voltage, power spectrum density, energy percent of poloidal modes, dominant spatial structures and temporal structures of poloidal modes at different plasma pressures are plotted. The results indicate that the MHD activities at the pressure of 2.5 Torr are less than them at other pressures. It also has been shown that in the stable area of plasma and at the pressure of 2.5 Torr, the magnetic force and the force of plasma pressure are in balance with each other and the MHD activities are at their lowest level.

  4. Diagnostic development and support of MHD (magnetohydrodynamics) test facilities

    Energy Technology Data Exchange (ETDEWEB)

    1989-07-01

    Mississippi State University (MSU) is developing diagnostic instruments for Magnetohydrodynamics (MHD) power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for HRSR support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with MHD Energy Center computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. MSU personnel will also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs.

  5. Effect of slip velocity on oscillatory MHD flow of stretched surface ...

    African Journals Online (AJOL)

    The study of unsteady magnetohydrodynamic heat and mass transfer in MHD flow of an incompressible, electrically conducting, viscous fluid past an infinite vertical porous plate along with porous medium of time dependent permeability with radiative heat transfer and variable suction has been made. Analytical solution of ...

  6. Several hundred megawatt MHD units

    International Nuclear Information System (INIS)

    Pishchikov, S.; Pinkhasik, D.; Sidorov, V.

    1978-01-01

    The features are described of the future MHD unit U-25 tested at the Institute of High Temperatures of the Academy of Sciences of the USSR. The attainable thermal load of the combustion chamber is 290x10 6 kJ/m 3 .h. Three types of channel were tested, i.e., the Faraday channel divided into sections with modular insulating walls, the diagonal channel without metal body, and an improved Faraday channel with an output of 20 MW. The described MHD generator is equipped with an inverter which transforms direct current into alternating current, continuously adjusts the load from no-load operation to short-circuit connection and maintains the desired electrical voltage independently of the changes in loading. A new technique of connecting and disconnecting the oxygen equipment was developed which considerably reduces the time of start-up and shut-down. Natural gas is used for heating the air heaters. All equipment used in the operation of the MHD generator is remote controlled by computer or manually. (J.B.)

  7. Several hundred megawatt MHD units

    Energy Technology Data Exchange (ETDEWEB)

    Pishchikov, S; Pinkhasik, D; Sidorov, V

    1978-07-01

    The features are described of the future MHD unit U-25 tested at the Institute of High Temperatures of the Academy of Sciences of the USSR. The attainable thermal load of the combustion chamber is 290x10/sup 6/ kJ/m/sup 3/.h. Three types of channel were tested, i.e., the Faraday channel divided into sections with modular insulating walls, the diagonal channel without metal body, and an improved Faraday channel with an output of 20 MW. The described MHD generator is equipped with an inverter which transforms direct current into alternating current, continuously adjusts the load from no-load operation to short-circuit connection and maintains the desired electrical voltage independently of the changes in loading. A new technique of connecting and disconnecting the oxygen equipment was developed which considerably reduces the time of start-up and shut-down. Natural gas is used for heating the air heaters. All equipment used in the operation of the MHD generator is remote controlled by computer or manually.

  8. Method of operating a MHD power plant

    International Nuclear Information System (INIS)

    Wysk, S.R.

    1982-01-01

    A fossil fuel is burned substoichiometrically in the combustor of a mhd power plant to produce a high temperature, fuelrich product gas. The product gas is passed through a mhd channel to generate electricity. A reducing agent, preferably natural gas or hydrocarbon, is injected into the fuelrich product gas leaving the mhd generator; and the resulting mixture is held at a temperature in the range of 950 to 1500 0 C for about 1 second to permit the reducing agent to decompose a portion of the nitrogen oxides formed in the combustor. The fuel-rich product gas then passes thru an afterburner wherein combustion is completed and any excess reducing agent is consumed

  9. Pseudo-MHD ballooning modes in tokamak plasmas

    International Nuclear Information System (INIS)

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

    1996-08-01

    The MHD description of a plasma is extended to allow electrons to have both fluid-like and adiabatic-regime responses within an instability eigenmode. In the resultant open-quotes pseudo-MHDclose quotes model, magnetic field line bending is reduced in the adiabatic electron regime. This makes possible a new class of ballooning-type, long parallel extent, MHD-like instabilities in tokamak plasmas for α > s 2 (2 7/3 /9) (r p /R 0 ) or-d√Β/dr > (2 1/6 /3)(s/ R 0q ), which is well below the ideal-MHD stability boundary. The marginally stable pressure profile is similar in both magnitude and shape to that observed in ohmically heated tokamak plasmas

  10. MHD/gas turbine systems designed for low cooling water requirements

    International Nuclear Information System (INIS)

    Annen, K.D.; Eustis, R.H.

    1983-01-01

    The MHD/gas turbine combined-cycle system has been designed specifically for applications where the availability of cooling water is very limited. The base case systems which were studied consist of a coal-fired MHD plant with an air turbine bottoming plant and require no cooling water. In addition to the base case systems, systems were considered which included the addition of a vapor cycle bottoming plant to improve the thermal efficiency. These systems require a small amount of cooling water. The results show that the MHD/gas turbine systems have very good thermal and economic performances. The base case I MHD/gas turbine system (782 MW /SUB e/ ) requires no cooling water, has a heat rate which is 13% higher, and a cost of electricity which is only 7% higher than a comparable MHD/steam system (878 MW /SUB e/ ) having a cooling tower heat load of 720 MW. The case I vapor cycle bottomed systems have thermal and economic performances which approach and even exceed those of the MHD/steam system, while having substantially lower cooling water requirements. Performances of a second-generation MHD/gas turbine system and an oxygen-enriched, early commercial system are also evaluated. An analysis of nitric oxide emissions shows compliance with emission standards

  11. 3D nonlinear MHD simulations of ultra-low q plasmas

    International Nuclear Information System (INIS)

    Bonfiglio, D.; Cappello, S.; Piovan, R.; Zanotto, L.; Zuin, M.

    2008-01-01

    Magnetohydrodynamic (MHD) phenomena occurring in the ultra-low safety factor (ULq) configuration are investigated by means of 3D nonlinear MHD simulations. The ULq configuration, a screw pinch characterized by the edge safety factor q edge in the interval 0 edge edge values which are about the major rational numbers, suggesting plasma self-organization. Similar behaviour is observed in experimental ULq discharges, like those recently obtained exploiting the flexibility of the RFX-mod device. The transition of q edge from a major rational number to the next one occurs together with the development of a kink deformation of the plasma column, whose stabilization yields a nearly axisymmetric state with a rather flat q profile. Numerical simulations also show that it is possible to sustain either of the two conditions, namely, the saturated kink helical configuration and the axisymmetric one, by forcing q edge at a suitable value. Finally, the effects of this MHD phenomenology on the confinement properties of ULq plasmas are discussed.

  12. Chemical, Biological, and Radiological (CBR) Contamination Survivability, Small Items of Equipment

    Science.gov (United States)

    2012-06-22

    contaminated with CWAs. May cause hardening or swelling of the sealant, which may weaken the seal. Rivet Stainless steel Not expected to have any effect...fallout, and nuclear survivability, which covers initial nu- clear weapon effects including Electromagnetic Pulse (EMP). Combat Developer . A...EA environmental assessment ECBC Edgewood Chemical Biological Center EMP electromagnetic pulse FD/SC Failure Definition/Scoring Criteria FM

  13. Hall effects on unsteady MHD flow between two rotating disks with non-coincident parallel axes

    Energy Technology Data Exchange (ETDEWEB)

    Barik, R.N., E-mail: barik.rabinarayan@rediffmail.com [Department of Mathematics, Trident Academy of Technology, Bhubaneswar (India); Dash, G.C., E-mail: gcdash@indiatimes.com [Department of Mathematics, S.O.A. University, Bhubaneswar (India); Rath, P.K., E-mail: pkrath_1967@yahoo.in [Department of Mathematics, B.R.M. International Institute of Technology, Bhubaneswar (India)

    2013-01-15

    Hall effects on the unsteady MHD rotating flow of a viscous incompressible electrically conducting fluid between two rotating disks with non-coincident parallel axes have been studied. There exists an axisymmetric solution to this problem. The governing equations are solved by applying Laplace transform method. It is found that the torque experienced by the disks decreases with an increase in either the Hall parameter, m or the rotation parameter, S{sup 2}. Further, the axis of rotation has no effect on the fluid flow. (author)

  14. Hall effects on unsteady MHD flow between two rotating disks with non-coincident parallel axes

    International Nuclear Information System (INIS)

    Barik, R.N.; Dash, G.C.; Rath, P.K.

    2013-01-01

    Hall effects on the unsteady MHD rotating flow of a viscous incompressible electrically conducting fluid between two rotating disks with non-coincident parallel axes have been studied. There exists an axisymmetric solution to this problem. The governing equations are solved by applying Laplace transform method. It is found that the torque experienced by the disks decreases with an increase in either the Hall parameter, m or the rotation parameter, S 2 . Further, the axis of rotation has no effect on the fluid flow. (author)

  15. An approach to verification and validation of MHD codes for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Smolentsev, S., E-mail: sergey@fusion.ucla.edu [University of California, Los Angeles (United States); Badia, S. [Centre Internacional de Mètodes Numèrics en Enginyeria, Barcelona (Spain); Universitat Politècnica de Catalunya – Barcelona Tech (Spain); Bhattacharyay, R. [Institute for Plasma Research, Gandhinagar, Gujarat (India); Bühler, L. [Karlsruhe Institute of Technology (Germany); Chen, L. [University of Chinese Academy of Sciences, Beijing (China); Huang, Q. [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui (China); Jin, H.-G. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Krasnov, D. [Technische Universität Ilmenau (Germany); Lee, D.-W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Mas de les Valls, E. [Centre Internacional de Mètodes Numèrics en Enginyeria, Barcelona (Spain); Universitat Politècnica de Catalunya – Barcelona Tech (Spain); Mistrangelo, C. [Karlsruhe Institute of Technology (Germany); Munipalli, R. [HyPerComp, Westlake Village (United States); Ni, M.-J. [University of Chinese Academy of Sciences, Beijing (China); Pashkevich, D. [St. Petersburg State Polytechnical University (Russian Federation); Patel, A. [Universitat Politècnica de Catalunya – Barcelona Tech (Spain); Pulugundla, G. [University of California, Los Angeles (United States); Satyamurthy, P. [Bhabha Atomic Research Center (India); Snegirev, A. [St. Petersburg State Polytechnical University (Russian Federation); Sviridov, V. [Moscow Power Engineering Institute (Russian Federation); Swain, P. [Bhabha Atomic Research Center (India); and others

    2015-11-15

    Highlights: • Review of status of MHD codes for fusion applications. • Selection of five benchmark problems. • Guidance for verification and validation of MHD codes for fusion applications. - Abstract: We propose a new activity on verification and validation (V&V) of MHD codes presently employed by the fusion community as a predictive capability tool for liquid metal cooling applications, such as liquid metal blankets. The important steps in the development of MHD codes starting from the 1970s are outlined first and then basic MHD codes, which are currently in use by designers of liquid breeder blankets, are reviewed. A benchmark database of five problems has been proposed to cover a wide range of MHD flows from laminar fully developed to turbulent flows, which are of interest for fusion applications: (A) 2D fully developed laminar steady MHD flow, (B) 3D laminar, steady developing MHD flow in a non-uniform magnetic field, (C) quasi-two-dimensional MHD turbulent flow, (D) 3D turbulent MHD flow, and (E) MHD flow with heat transfer (buoyant convection). Finally, we introduce important details of the proposed activities, such as basic V&V rules and schedule. The main goal of the present paper is to help in establishing an efficient V&V framework and to initiate benchmarking among interested parties. The comparison results computed by the codes against analytical solutions and trusted experimental and numerical data as well as code-to-code comparisons will be presented and analyzed in companion paper/papers.

  16. Down-regulation of EMP1 is associated with epithelial hyperplasia and metaplasia in nasal polyps.

    Science.gov (United States)

    Yu, Xue Min; Li, Chun Wei; Li, Ying Ying; Liu, Jing; Lin, Zhi Bin; Li, Tian Ying; Zhao, Li; Pan, Xin Liang; Shi, Li; Wang, De Yun

    2013-11-01

    The aim of this study was to assess protein and mRNA expression of epithelial membrane protein 1 (EMP1) in the nasal mucosa of patients with nasal polyps (NP), and to determine what changes occur in response to glucocorticosteroid (GC) treatment. NP tissue was obtained from 55 patients, 18 of whom were treated with nasal GCs (i.e. these 18 patients had NP biopsies taken before and after treatment). Biopsies of inferior turbinate mucosa from 30 healthy subjects were used as controls. Quantitative PCR and immunohistochemistry were performed to determine the expression levels of EMP1. EMP1 mRNA expression was significantly lower (2.77-fold) in tissues from NP patients before GC treatment when compared to controls, but was increased in these patients after GC treatment. EMP1 staining in nasal epithelium co-localized with both basal (p63(+)) and differentiated (CK18(+)) epithelial cells. Their immunoreactivity was significantly greater in controls than NP patients. EMP1 mRNA levels were lower in the epithelium with severe hyperplasia (1.79-fold) or with metaplasia (1.85-fold) as compared to those with mild to moderate hyperplasia or non-metaplastic epithelium, respectively. Positive correlations between EMP1 and other epithelial cell-related gene (e.g. JUN, PTGS2, AREG etc.) mRNAs were observed. EMP1 could be a biomarker for aberrant epithelial remodelling and metaplasia in chronic inflammatory upper airway mucosa (e.g. NP). © 2013 John Wiley & Sons Ltd.

  17. Liquid metal MHD studies with non-magnetic and ferro-magnetic structural material

    Energy Technology Data Exchange (ETDEWEB)

    Patel, A., E-mail: anipatel2009@gmail.com [Institute of Plasma Research, Gandhinagar 382428, Gujarat (India); Bhattacharyay, R. [Institute of Plasma Research, Gandhinagar 382428, Gujarat (India); Swain, P.K.; Satyamurthy, P. [Bhabha Atomic Research Center, Mumbai 400085, Maharashtra (India); Sahu, S.; Rajendrakumar, E. [Institute of Plasma Research, Gandhinagar 382428, Gujarat (India); Ivanov, S.; Shishko, A.; Platacis, E.; Ziks, A. [Institute of Physics, University of Latvia, Salaspils 2169 (Latvia)

    2014-10-15

    Highlights: • Effect of structural material on liquid metal MHD phenomena is studied. • Two identical test sections, one made of SS316L (non-magnetic) and other made of SS430 (ferromagnetic) structural material, are considered. • Wall electric potential and liquid metal pressure drop are compared under various experimental conditions. • Experimental results suggest screening of external magnetic field for SS430 material below the saturation magnetic field. - Abstract: In most of the liquid metal MHD experiments reported in the literature to study liquid breeder blanket performance, SS316/SS304 grade steels are used as the structural material which is non-magnetic. On the other hand, the structural material for fusion blanket systems has been proposed to be ferritic martensitic grade steel (FMS) which is ferromagnetic in nature. In the recent experimental campaign, liquid metal MHD experiments have been carried out with two identical test sections: one made of SS316L (non-magnetic) and another with SS430 (ferromagnetic), to compare the effect of structural materials on MHD phenomena for various magnetic fields (up to 4 T). The maximum Hartmann number and interaction number are 1047 and 300, respectively. Each test section consists of square channel (25 mm × 25 mm) cross-section with two U bends, with inlet and outlet at the middle portion of two horizontal legs, respectively. Pb–Li enters into the test section through a square duct and distributed into two parallel paths through a partition plate. In each parallel path, it travels ∼0.28 m length in plane perpendicular to the magnetic field and faces two 90° bends before coming out of the test section through a single square duct. The wall electrical potential and MHD pressure drop across the test sections are compared under identical experimental conditions. Similar MHD behavior is observed with both the test section at higher value of the magnetic field (>2 T)

  18. MHD stability of vertically asymmetric tokamak equilibria

    International Nuclear Information System (INIS)

    Dalhed, H.E.; Grimm, R.C.; Johnson, J.L.

    1981-03-01

    The ideal MHD stability properties of a special class of vertically asymmetric tokamak equilibria are examined. The calculations confirm that no major new physical effects are introduced and the modifications can be understood by conventional arguments. The results indicate that significant departures from up-down symmetry can be tolerated before the reduction in β becomes important for reactor operation

  19. Exponential Megapriming PCR (EMP) Cloning—Seamless DNA Insertion into Any Target Plasmid without Sequence Constraints

    Science.gov (United States)

    Ulrich, Alexander; Andersen, Kasper R.; Schwartz, Thomas U.

    2012-01-01

    We present a fast, reliable and inexpensive restriction-free cloning method for seamless DNA insertion into any plasmid without sequence limitation. Exponential megapriming PCR (EMP) cloning requires two consecutive PCR steps and can be carried out in one day. We show that EMP cloning has a higher efficiency than restriction-free (RF) cloning, especially for long inserts above 2.5 kb. EMP further enables simultaneous cloning of multiple inserts. PMID:23300917

  20. Helium refrigerator-liquefier system for MHD generator

    International Nuclear Information System (INIS)

    Akiyama, Y.; Ishii, H.; Mori, Y.; Yamamoto, M.; Wada, R.; Ando, M.

    1974-01-01

    MHD power generators have been investigated in the Electro-Technical Laboratory as one of the National Research and Development Programmes. A helium refrigerator-liquefier system has been developed to cool the superconducting magnet for a 1000 kW class MHD power generator. The turboexpander with low temperature gas bearings and an alternator had been developed for the MHD project at the Electro-Technical Laboratory previously. The liquefaction capacity is 250 iota/h and the refrigeration power is 2.9 kW at 20 K. The superconducting magnet is 50 tons and the cryostat has a liquid helium volume of 2700 iota. The evaporation rate is 60 to 80 iota/h. It takes, in all 2 to 3 weeks to fill the cryostat with liquid helium. (author)

  1. Numerical study of MHD supersonic flow control

    Science.gov (United States)

    Ryakhovskiy, A. I.; Schmidt, A. A.

    2017-11-01

    Supersonic MHD flow around a blunted body with a constant external magnetic field has been simulated for a number of geometries as well as a range of the flow parameters. Solvers based on Balbas-Tadmor MHD schemes and HLLC-Roe Godunov-type method have been developed within the OpenFOAM framework. The stability of the solution varies depending on the intensity of magnetic interaction The obtained solutions show the potential of MHD flow control and provide insights into for the development of the flow control system. The analysis of the results proves the applicability of numerical schemes, that are being used in the solvers. A number of ways to improve both the mathematical model of the process and the developed solvers are proposed.

  2. MHD generator performance analysis for the Advanced Power Train study

    Science.gov (United States)

    Pian, C. C. P.; Hals, F. A.

    1984-01-01

    Comparative analyses of different MHD power train designs for early commercial MHD power plants were performed for plant sizes of 200, 500, and 1000 MWe. The work was conducted as part of the first phase of a planned three-phase program to formulate an MHD Advanced Power Train development program. This paper presents the results of the MHD generator design and part-load analyses. All of the MHD generator designs were based on burning of coal with oxygen-enriched air preheated to 1200 F. Sensitivities of the MHD generator design performance to variations in power plant size, coal type, oxygen enrichment level, combustor heat loss, channel length, and Mach number were investigated. Basd on these sensitivity analyses, together with the overall plant performance and cost-of-electricity analyses, as well as reliability and maintenance considerations, a recommended MHD generator design was selected for each of the three power plants. The generators for the 200 MWe and 500 MWe power plant sizes are supersonic designs. A subsonic generator design was selected for the 1000 MWe plant. Off-design analyses of part-load operation of the supersonic channel selected for the 200 MWe power plant were also conductd. The results showed that a relatively high overall net plant efficiency can be maintained during part-laod operation with a supersonic generator design.

  3. A MHD channel study for the ETF conceptual design

    Science.gov (United States)

    Wang, S. Y.; Staiger, P. J.; Smith, J. M.

    1981-01-01

    The procedures and computations used to identify an MHD channel for a 540 mW(I) EFT-scale plant are presented. Under the assumed constraints of maximum E(x), E(y), J(y) and Beta; results show the best plant performance is obtained for active length, L is approximately 12 M, whereas in the initial ETF studies, L is approximately 16 M. As MHD channel length is reduced from 16 M, the channel enthalpy extraction falls off, slowly. This tends to reduce the MHD power output; however, the shorter channels result in lower heat losses to the MHD channel cooling water which allows for the incorporation of more low pressure boiler feedwater heaters into the system and an increase in steam plant efficiency. The net result of these changes is a net increase in the over all MHD/steam plant efficiency. In addition to the sensitivity of various channel parameters, the trade-offs between the level of oxygen enrichment and the electrical stress on the channel are also discussed.

  4. Formation, structure, and stability of MHD intermediate shocks

    International Nuclear Information System (INIS)

    Wu, C.C.

    1990-01-01

    Contrary to the usual belief that MHD intermediate shocks are extraneous, the author has recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear wave steepening from continuous waves. In this paper, the formation, structure and stability of intermediate shocks in dissipative MHD are considered in detail. The differences between the conventional theory and his are pointed out and clarified. He shows that all four types of intermediate shocks can be formed from smooth waves. He also shows that there are free parameters in the structure of the intermediate shocks, and that these parameters are related to the shock stability. In addition, he shows that a rotational discontinuity can not exist with finite width, indicate how this is related to the existence of time-dependent intermediate shocks, and show why the conventional theory is not a good approximation to dissipative MHD solutions whenever there is rotation in magnetic field

  5. MHD power station with coal gasification

    International Nuclear Information System (INIS)

    Brzozowski, W.S.; Dul, J.; Pudlik, W.

    1976-01-01

    A description is given of the proposed operating method of a MHD-power station including a complete coal gasification into lean gas with a simultaneous partial gas production for the use of outside consumers. A comparison with coal gasification methods actually being used and full capabilities of power stations heated with coal-derived gas shows distinct advantages resulting from applying the method of coal gasification with waste heat from MHD generators working within the boundaries of the thermal-electric power station. (author)

  6. Summary of results of research on magneto hydrodynamic (MHD) generation in fiscal 1977; 1977 nendo denji ryutai (MHD) hatsuden kenkyu seika gaiyo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1978-08-01

    This is the summary of results of the research on MHD generation in fiscal 1977. In the experimental studies on MHD generators using a copper/iron magnet, the combustor of the Mark 7 generator was manufactured and installed, as were the supply systems of fuel, oxygen, air, seed, sulfur dioxide, cooling water, etc., respectively of the Mark 7 generator based on the design implemented in the previous year. In the studies on element technologies, various tests were performed, namely, immersion tests by K{sub 2}SO{sub 4} solution for electrode materials; tests of corrosion resistance, thermal shock resistance, and compatibility with electrode materials, for insulation wall materials; and material selection tests, based on a dynamic state, for consumption quantity and distribution, surface temperature and heat flow, measurement of arc spot generating critical current and electrode lowering voltage, etc.. In the research on the MHD generation system, examinations were carried out on the position of MHD generation as a total system, as well as on a system of a practical plant, MHD generation for peak load, superconducting magnet, etc. In addition, examinations were also conducted on the Mark 7 calculation, Mark 8 plan, surveys on overseas trend, etc. (NEDO)

  7. The effect of compressive viscosity and thermal conduction on the longitudinal MHD waves

    Science.gov (United States)

    Bahari, K.; Shahhosaini, N.

    2018-05-01

    longitudinal Magnetohydrodynamic (MHD) oscillations have been studied in a slowly cooling coronal loop, in the presence of thermal conduction and compressive viscosity, in the linear MHD approximation. WKB method has been used to solve the governing equations. In the leading order approximation the dispersion relation has been obtained, and using the first order approximation the time dependent amplitude has been determined. Cooling causes the oscillations to amplify and damping mechanisms are more efficient in hot loops. In cool loops the oscillation amplitude increases with time but in hot loops the oscillation amplitude decreases with time. Our conclusion is that in hot loops the efficiency of the compressive viscosity in damping longitudinal waves is comparable to that of the thermal conduction.

  8. Exponential megapriming PCR (EMP cloning--seamless DNA insertion into any target plasmid without sequence constraints.

    Directory of Open Access Journals (Sweden)

    Alexander Ulrich

    Full Text Available We present a fast, reliable and inexpensive restriction-free cloning method for seamless DNA insertion into any plasmid without sequence limitation. Exponential megapriming PCR (EMP cloning requires two consecutive PCR steps and can be carried out in one day. We show that EMP cloning has a higher efficiency than restriction-free (RF cloning, especially for long inserts above 2.5 kb. EMP further enables simultaneous cloning of multiple inserts.

  9. Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  10. MHD stability analysis of helical system plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yuji

    2000-01-01

    Several topics of the MHD stability studies in helical system plasmas are reviewed with respect to the linear and ideal modes mainly. Difference of the method of the MHD stability analysis in helical system plasmas from that in tokamak plasmas is emphasized. Lack of the cyclic (symmetric) coordinate makes an analysis more difficult. Recent topic about TAE modes in a helical system is also described briefly. (author)

  11. Outline of fiscal 1967 achievements in research on MHD power generation; 1967 nendo MHD hatsuden kenkyu seika gaiyo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1968-09-01

    Compiled are the results of studies conducted in fiscal 1967 on MHD (magnetohydrodynamic) power generation. In the test operation and modification of a 1,000kW-class MHD power generator at the Electrical Research Laboratory, a test is conducted using Faraday-type electrodes. It is then found that this configuration results in a maximum output of approximately 700kW, which is less than expected. In the experimental construction at the Hitachi, Ltd., of a machine capable of a long-term operation, an MHD power generator is built for a continuous operation of 100 hours with an maximum output of 2kW, and a 110-hour power generation is successfully achieved with a maximum output of 1.9kW. In the research and development of heat exchangers, tests are conducted for a bulkhead type heat exchanger, heat accumulator type heat exchanger, molten slag type heat exchanger, and a gas/liquid 2-phase flow type heat exchanger. In the study of heat-resisting insulators, materials based on zirconate, magnesia, thoria, zirconia, etc., are tested. In addition, studies are conducted on electrode materials, superconductive electromagnets (small superconductive electromagnets for MHD power generators, turbine type helium liquefiers, superconductive wires for 70-kilogauss electromagnets, etc.), and thermal performance rating. (NEDO)

  12. Report on results of contract research. 'Research on MHD generation system'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1982-03-01

    'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1981 reported. This year, technological reexamination was conducted for a 2,000 MWt commercial MHD generation plant, with evaluation carried out on the cost performance including the construction and operation cost. In addition, for the purpose of intermediate R and D towards the practicability, examination was also conducted on a system structure, concrete specifications of component element, cost of R and D including operation expenses for example, concerning an 100 MWt class experimental plant and a 500 MWt class plant. In the investigation of the overseas trend, information was summarized in detail on the experimental devices, combustors, generation channels, electrode materials, electrode phenomena, theoretical analyses, seeds, slag, component equipment, instrumental technologies, conceptual designs of generation plant, commercial plant, etc., in Soviet Union, China, Holland, India and EPRI, on the basis of the materials from the 19th MHD symposium held in UTSI and from the coal MHD specialist conference held in Sydney. (NEDO)

  13. Direct numerical simulation of MHD flow with electrically conducting wall

    International Nuclear Information System (INIS)

    Satake, S.; Kunugi, T.; Naito, N.; Sagara, A.

    2006-01-01

    The 2D vortex problem and 3D turbulent channel flow are treated numerically to assess the effect of electrically conducting walls on turbulent MHD flow. As a first approximation, the twin vortex pair is considered as a model of a turbulent eddy near the wall. As the eddy approaches and collides with the wall, a high value electrical potential is induced inside the wall. The Lorentz force, associated with the potential distribution, reduces the velocity gradient in the near-wall region. When considering a fully developed turbulent channel flow, a high electrical conductivity wall was chosen to emphasize the effect of electromagnetic coupling between the wall and the flow. The analysis was performed using DNS. The results are compared with a non-MHD flow and MHD flow in the insulated channel. The mean velocity within the logarithmic region in the case of the electrically conducting wall is slightly higher than that in the non-conducting wall case. Thus, the drag is smaller compared to that in the non-conducting wall case due to a reduction of the Reynolds stress in the near wall region through the Lorentz force. This mechanism is explained via reduction of the production term in the Reynolds shear stress budget

  14. MHD Hele-Shaw flow of Rivlin-Ericksen fluid

    International Nuclear Information System (INIS)

    Ghosh, B.C.; Sengupta, P.R.

    1995-01-01

    In this paper, an attempt has been made to study the MHD Hele-Shaw flow of Rivlin-Ericksen visco-elastic fluid assuming the pressure gradient to be proportional to exp (-nt). The velocity components are obtained and the effect of visco-elasticity is discussed on velocity components. (author). 8 refs

  15. MHD deceleration of fusion reaction products

    International Nuclear Information System (INIS)

    Chow, S.; Bohachevsky, I.O.

    1979-04-01

    The feasibility of magnetohydrodynamic (MHD) deceleration of fuel pellet debris ions exiting from an inertial confinement fusion (ICF) reactor cavity is investigated using one-dimensional flow equations. For engineering reasons, induction-type devices are emphasized; their performance characteristics are similar to those of electrode-type decelerators. Results of the analysis presented in this report indicate that MHD decelerators can be designed within conventional magnet technology to not only decelerate the high-energy fusion pellet debris ions but also to produce some net electric power in the process

  16. Experimental investigation of MHD heat transfer in a vertical round tube affected by transverse magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, I.A., E-mail: corpuskula@gmail.com; Sviridov, E.V.; Sviridov, V.G.; Razuvanov, N.G.

    2016-11-15

    Highlights: • Local and averaged heat transfer coefficient are measured. • Free convection influence on MHD-flow is investigated. • The region with the free convection effect of MHD-heat transfer is found. • Temperature low-frequency fluctuations of abnormally high amplitude are detected. • Analysis of the MHD-heat transfer experimental data is performed. - Abstract: The article is devoted to the results of experimental investigation of heat transfer for a downward mercury flow in a vertical round tube in the presence of a transverse magnetic with non-uniform heat flux along the tube circumference.

  17. Pulsed fusion space propulsion: Computational Magneto-Hydro Dynamics of a multi-coil parabolic reaction chamber

    Science.gov (United States)

    Romanelli, Gherardo; Mignone, Andrea; Cervone, Angelo

    2017-10-01

    Pulsed fusion propulsion might finally revolutionise manned space exploration by providing an affordable and relatively fast access to interplanetary destinations. However, such systems are still in an early development phase and one of the key areas requiring further investigations is the operation of the magnetic nozzle, the device meant to exploit the fusion energy and generate thrust. One of the last pulsed fusion magnetic nozzle design is the so called multi-coil parabolic reaction chamber: the reaction is thereby ignited at the focus of an open parabolic chamber, enclosed by a series of coaxial superconducting coils that apply a magnetic field. The field, beside confining the reaction and preventing any contact between hot fusion plasma and chamber structure, is also meant to reflect the explosion and push plasma out of the rocket. Reflection is attained thanks to electric currents induced in conductive skin layers that cover each of the coils, the change of plasma axial momentum generates thrust in reaction. This working principle has yet to be extensively verified and computational Magneto-Hydro Dynamics (MHD) is a viable option to achieve that. This work is one of the first detailed ideal-MHD analysis of a multi-coil parabolic reaction chamber of this kind and has been completed employing PLUTO, a freely distributed computational code developed at the Physics Department of the University of Turin. The results are thus a preliminary verification of the chamber's performance. Nonetheless, plasma leakage through the chamber structure has been highlighted. Therefore, further investigations are required to validate the chamber design. Implementing a more accurate physical model (e.g. Hall-MHD or relativistic-MHD) is thus mandatory, and PLUTO shows the capabilities to achieve that.

  18. Investigation of MHD instabilities and control in KSTAR preparing for high beta operation

    Science.gov (United States)

    Park, Y. S.; Sabbagh, S. A.; Bialek, J. M.; Berkery, J. W.; Lee, S. G.; Ko, W. H.; Bak, J. G.; Jeon, Y. M.; Park, J. K.; Kim, J.; Hahn, S. H.; Ahn, J.-W.; Yoon, S. W.; Lee, K. D.; Choi, M. J.; Yun, G. S.; Park, H. K.; You, K.-I.; Bae, Y. S.; Oh, Y. K.; Kim, W.-C.; Kwak, J. G.

    2013-08-01

    Initial H-mode operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) is expanded to higher normalized beta and lower plasma internal inductance moving towards design target operation. As a key supporting device for ITER, an important goal for KSTAR is to produce physics understanding of MHD instabilities at long pulse with steady-state profiles, at high normalized beta, and over a wide range of plasma rotation profiles. An advance from initial plasma operation is a significant increase in plasma stored energy and normalized beta, with Wtot = 340 kJ, βN = 1.9, which is 75% of the level required to reach the computed ideal n = 1 no-wall stability limit. The internal inductance was lowered to 0.9 at sustained H-mode duration up to 5 s. In ohmically heated plasmas, the plasma current reached 1 MA with prolonged pulse length up to 12 s. Rotating MHD modes are observed in the device with perturbations having tearing rather than ideal parity. Modes with m/n = 3/2 are triggered during the H-mode phase but are relatively weak and do not substantially reduce Wtot. In contrast, 2/1 modes to date only appear when the plasma rotation profiles are lowered after H-L back-transition. Subsequent 2/1 mode locking creates a repetitive collapse of βN by more than 50%. Onset behaviour suggests the 3/2 mode is close to being neoclassically unstable. A correlation between the 2/1 mode amplitude and local rotation shear from an x-ray imaging crystal spectrometer suggests that the rotation shear at the mode rational surface is stabilizing. As a method to access the ITER-relevant low plasma rotation regime, plasma rotation alteration by n = 1, 2 applied fields and associated neoclassical toroidal viscosity (NTV) induced torque is presently investigated. The net rotation profile change measured by a charge exchange recombination diagnostic with proper compensation of plasma boundary movement shows initial evidence of non-resonant rotation damping by the n = 1, 2 applied

  19. Investigation of MHD instabilities and control in KSTAR preparing for high beta operation

    International Nuclear Information System (INIS)

    Park, Y.S.; Sabbagh, S.A.; Bialek, J.M.; Berkery, J.W.; Lee, S.G.; Ko, W.H.; Bak, J.G.; Jeon, Y.M.; Kim, J.; Hahn, S.H.; Yoon, S.W.; Lee, K.D.; You, K.-I.; Bae, Y.S.; Oh, Y.K.; Park, J.K.; Ahn, J.-W.; Choi, M.J.; Yun, G.S.; Park, H.K.

    2013-01-01

    Initial H-mode operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) is expanded to higher normalized beta and lower plasma internal inductance moving towards design target operation. As a key supporting device for ITER, an important goal for KSTAR is to produce physics understanding of MHD instabilities at long pulse with steady-state profiles, at high normalized beta, and over a wide range of plasma rotation profiles. An advance from initial plasma operation is a significant increase in plasma stored energy and normalized beta, with W tot = 340 kJ, β N = 1.9, which is 75% of the level required to reach the computed ideal n = 1 no-wall stability limit. The internal inductance was lowered to 0.9 at sustained H-mode duration up to 5 s. In ohmically heated plasmas, the plasma current reached 1 MA with prolonged pulse length up to 12 s. Rotating MHD modes are observed in the device with perturbations having tearing rather than ideal parity. Modes with m/n = 3/2 are triggered during the H-mode phase but are relatively weak and do not substantially reduce W tot . In contrast, 2/1 modes to date only appear when the plasma rotation profiles are lowered after H–L back-transition. Subsequent 2/1 mode locking creates a repetitive collapse of β N by more than 50%. Onset behaviour suggests the 3/2 mode is close to being neoclassically unstable. A correlation between the 2/1 mode amplitude and local rotation shear from an x-ray imaging crystal spectrometer suggests that the rotation shear at the mode rational surface is stabilizing. As a method to access the ITER-relevant low plasma rotation regime, plasma rotation alteration by n = 1, 2 applied fields and associated neoclassical toroidal viscosity (NTV) induced torque is presently investigated. The net rotation profile change measured by a charge exchange recombination diagnostic with proper compensation of plasma boundary movement shows initial evidence of non-resonant rotation damping by the n = 1, 2

  20. Sawtooth oscillations as MHD relaxation process in a plasma

    International Nuclear Information System (INIS)

    Yoshida, Zensho; Inoue, Nobuyuki; Ogawa, Yuichi

    1992-01-01

    The sawtooth oscillation in a tokamak plasma is a spontaneous relaxation process accompanying global instabilities which behave to reduce the internal magnetic energy. This phenomenon has a similarity to the MHD relaxation processes in Reversed Field Pinch (RFP) and Ultra Low Q (ULQ) plasmas. The self-stabilizing effect of instabilities with m (poloidal mode number) = 1 results in an increase in the central safety factor q(0). Nonlinear dynamics of m = 1 instabilities has been discussed both for global and local modes. The latter appears when a pitch minimum exists in the plasma, and is relevant to the compound sawtooth oscillation. The MHD relaxation is a restructuring process of the plasma current profile that is competitive with the resistive diffusion. (author)

  1. Accuracy of MHD simulations: Effects of simulation initialization in GUMICS-4

    Science.gov (United States)

    Lakka, Antti; Pulkkinen, Tuija; Dimmock, Andrew; Osmane, Adnane; Palmroth, Minna; Honkonen, Ilja

    2016-04-01

    We conducted a study aimed at revealing how different global magnetohydrodynamic (MHD) simulation initialization methods affect the dynamics in different parts of the Earth's magnetosphere-ionosphere system. While such magnetosphere-ionosphere coupling codes have been used for more than two decades, their testing still requires significant work to identify the optimal numerical representation of the physical processes. We used the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS-4), the only European global MHD simulation being developed by the Finnish Meteorological Institute. GUMICS-4 was put to a test that included two stages: 1) a 10 day Omni data interval was simulated and the results were validated by comparing both the bow shock and the magnetopause spatial positions predicted by the simulation to actual measurements and 2) the validated 10 day simulation run was used as a reference in a comparison of five 3 + 12 hour (3 hour synthetic initialisation + 12 hour actual simulation) simulation runs. The 12 hour input was not only identical in each simulation case but it also represented a subset of the 10 day input thus enabling quantifying the effects of different synthetic initialisations on the magnetosphere-ionosphere system. The used synthetic initialisation data sets were created using stepwise, linear and sinusoidal functions. Switching the used input from the synthetic to real Omni data was immediate. The results show that the magnetosphere forms in each case within an hour after the switch to real data. However, local dissimilarities are found in the magnetospheric dynamics after formation depending on the used initialisation method. This is evident especially in the inner parts of the lobe.

  2. MHD instabilities in astrophysical plasmas: very different from MHD instabilities in tokamaks!

    NARCIS (Netherlands)

    Goedbloed, J. P.

    2018-01-01

    The extensive studies of MHD instabilities in thermonuclear magnetic confinement experiments, in particular of the tokamak as the most promising candidate for a future energy producing machine, have led to an 'intuitive' description based on the energy principle that is very misleading for

  3. Studies of MHD stability using data mining technique in helical plasmas

    International Nuclear Information System (INIS)

    Yamamoto, Satoshi; Pretty, David; Blackwell, Boyd

    2010-01-01

    Data mining techniques, which automatically extract useful knowledge from large datasets, are applied to multichannel magnetic probe signals of several helical plasmas in order to identify and classify MHD instabilities in helical plasmas. This method is useful to find new MHD instabilities as well as previously identified ones. Moreover, registering the results obtained from data mining in a database allows us to investigate the characteristics of MHD instabilities with parameter studies. We introduce the data mining technique consisted of pre-processing, clustering and visualizations using results from helical plasmas in H-1 and Heliotron J. We were successfully able to classify the MHD instabilities using the criterion of phase differences of each magnetic probe and identify them as energetic-ion-driven MHD instabilities using parameter study in Heliotron J plasmas. (author)

  4. Preliminary analysis of 500 MWt MHD power plant with oxygen enrichment

    Science.gov (United States)

    1980-04-01

    An MHD Engineering Test Facility design concept is analyzed. A 500 MWt oxygen enriched MHD topping cycle integrated for combined cycle operation with a 400 MWe steam plant is evaluated. The MHD cycle uses Montana Rosebud coal and air enriched to 35 mole percent oxygen preheated to 1100 F. The steam plant is a 2535 psia/1000 F/1000 F reheat recycle that was scaled down from the Gilbert/Commonwealth Reference Fossil Plant design series. Integration is accomplished by blending the steam generated in the MHD heat recovery system with steam generated by the partial firing of the steam plant boiler to provide the total flow requirement of the turbine. The major MHD and steam plant auxiliaries are driven by steam turbines. When the MHD cycle is taken out of service, the steam plant is capable of stand-alone operation at turbine design throttle flow. This operation requires the full firing of the steam plant boiler. A preliminary feasibility assessment is given, and results on the system thermodynamics, construction scheduling, and capital costs are presented.

  5. EVIDENCE OF ACTIVE MHD INSTABILITY IN EULAG-MHD SIMULATIONS OF SOLAR CONVECTION

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, Nicolas; Strugarek, Antoine; Charbonneau, Paul, E-mail: nicolas.laws@gmail.ca, E-mail: strugarek@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, Qc H3C 3J7 (Canada)

    2015-11-10

    We investigate the possible development of magnetohydrodynamical instabilities in the EULAG-MHD “millennium simulation” of Passos and Charbonneau. This simulation sustains a large-scale magnetic cycle characterized by solar-like polarity reversals taking place on a regular multidecadal cadence, and in which zonally oriented bands of strong magnetic fields accumulate below the convective layers, in response to turbulent pumping from above in successive magnetic half-cycles. Key aspects of this simulation include low numerical dissipation and a strongly sub-adiabatic fluid layer underlying the convectively unstable layers corresponding to the modeled solar convection zone. These properties are conducive to the growth and development of two-dimensional instabilities that are otherwise suppressed by stronger dissipation. We find evidence for the action of a non-axisymmetric magnetoshear instability operating in the upper portions of the stably stratified fluid layers. We also investigate the possibility that the Tayler instability may be contributing to the destabilization of the large-scale axisymmetric magnetic component at high latitudes. On the basis of our analyses, we propose a global dynamo scenario whereby the magnetic cycle is driven primarily by turbulent dynamo action in the convecting layers, but MHD instabilities accelerate the dissipation of the magnetic field pumped down into the overshoot and stable layers, thus perhaps significantly influencing the magnetic cycle period. Support for this scenario is found in the distinct global dynamo behaviors observed in an otherwise identical EULAG-MHD simulations, using a different degree of sub-adiabaticity in the stable fluid layers underlying the convection zone.

  6. Observation of SOL Current Correlated with MHD Activity in NBI-heated DIII-D Tokamak Discharges

    International Nuclear Information System (INIS)

    Takahashi, H.; Fredrickson, E.D.; Schaffer, M.J.; Austin, M.E.; Evans, T.E.; Lao, L.L.; Watkins, J.G.

    2004-01-01

    This work investigates the potential roles played by the scrape-off-layer current (SOLC) in MHD activity of tokamak plasmas, including effects on stability. SOLCs are found during MHD activity that are: (1) slowly growing after a mode-locking-like event, (2) oscillating in the several kHz range and phase-locked with magnetic and electron temperature oscillations, (3) rapidly growing with a sub-ms time scale during a thermal collapse and a current quench, and (4) spiky in temporal behavior and correlated with spiky features in Da signals commonly identified with the edge localized mode (ELM). These SOLCs are found to be an integral part of the MHD activity, with a propensity to flow in a toroidally non-axisymmetric pattern and with magnitude potentially large enough to play a role in the MHD stability. Candidate mechanisms that can drive these SOLCs are identified: (a) toroidally non-axisymmetric thermoelectric potential, (b) electromotive force (EMF) from MHD activity, and (c) flux swing, both toroidal and poloidal, of the plasma column. An effect is found, stemming from the shear in the field line pitch angle, that mitigates the efficacy of a toroidally non-axisymmetric SOLC to generate a toroidally non-axisymmetric error field. Other potential magnetic consequences of the SOLC are identified: (i) its error field can introduce complications in feedback control schemes for stabilizing MHD activity and (ii) its toroidally non-axisymmetric field can be falsely identified as an axisymmetric field by the tokamak control logic and in equilibrium reconstruction. The radial profile of a SOLC observed during a quiescent discharge period is determined, and found to possess polarity reversals as a function of radial distance

  7. Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

    Science.gov (United States)

    Zhang, Ruobing; Liang, Dapeng; Zheng, Nanchen; Xiao, Jianfu; Mo, Mengbin; Li, Jing

    2013-03-01

    Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

  8. Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

    International Nuclear Information System (INIS)

    Zhang, Ruobing; Liang, Dapeng; Xiao, Jianfu; Mo, Mengbin; Li, Jing; Zheng, Nanchen

    2013-01-01

    Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

  9. On nonlinear MHD-stability of toroidal magnetized plasma

    International Nuclear Information System (INIS)

    Ilgisonis, V.I.; Pastukhov, V.P.

    1994-01-01

    The variational approach to analyze the nonlinear MHD stability of ideal plasma in toroidal magnetic field is proposed. The potential energy functional to be used is expressed in terms of complete set of independent Lagrangian invariants, that allows to take strictly into account all the restrictions inherent in the varied functions due to MHD dynamic equations. (author). 3 refs

  10. Efficient ion heating of tokamak plasma by application of positive and negative current pulse in TRIAM-1

    International Nuclear Information System (INIS)

    Toi, Kazuo; Hiraki, Naoji; Nakamura, Kazuo; Mitarai, Osamu; Kawai, Yoshinobu

    1980-01-01

    The efficient heating of bulk ions of tokamak plasma is observed by application of the pulsed toroidal electric field much higher than the Dreicer field with the positive and negative polarities for the ohmic heating field. No deleterious effect on the confinement properties of tokamak plasma appears by the heating. The decay time of ion temperature raised by the heating pulse agrees well with the prediction by the neoclassical transport theory. The magnitude of the current induced by the pulsed electric field with the positive polarity is limited by the violent current disruption. In the case of the negative polarity, this is limited by lack of the MHD equilibrium due to vanishing the total plasma current. The ratio of drift velocity to electron thermal one / attains around 0.5, which suggests that the efficient ion heating may be due to the current-driven turbulence. (author)

  11. Efficient ion heating of tokamak plasma by application of positive and negative current pulse in TRIAM-1

    Energy Technology Data Exchange (ETDEWEB)

    Toi, K; Hiraki, N; Nakamura, K; Mitarai, O; Kawai, Y [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1980-02-01

    The efficient heating of bulk ions of tokamak plasma is observed by application of the pulsed toroidal electric field much higher than the Dreicer field with the positive and negative polarities for the ohmic heating field. No deleterious effect on the confinement properties of tokamak plasma appears by the heating. The decay time of ion temperature raised by the heating pulse agrees well with the prediction by the neoclassical transport theory. The magnitude of the current induced by the pulsed electric field with the positive polarity is limited by the violent current disruption. In the case of the negative polarity, this is limited by lack of the MHD equilibrium due to vanishing the total plasma current. The ratio of drift velocity to electron thermal one / attains around 0.5, which suggests that the efficient ion heating may be due to the current-driven turbulence.

  12. Evaluation of the Effects of Ketoconazole and Voriconazole on the Pharmacokinetics of Oxcarbazepine and Its Main Metabolite MHD in Rats by UPLC-MS-MS.

    Science.gov (United States)

    Chen, Xinxin; Gu, Ermin; Wang, Shuanghu; Zheng, Xiang; Chen, Mengchun; Wang, Li; Hu, Guoxin; Cai, Jian-ping; Zhou, Hongyu

    2016-03-01

    Oxcarbazepine (OXC), a second-generation antiepileptic drug, undergoes rapid reduction with formation of the active metabolite 10,11-dihydro-10-hydroxy-carbazepine (MHD) in vivo. In this study, a method for simultaneous determination of OXC and MHD in rat plasma using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS-MS) was developed and validated. Under given chromatographic conditions, OXC, MHD and internal standard diazepam were separated well and quantified by electrospray positive ionization mass spectrometry in the multiple reaction monitoring transitions mode. The method validation demonstrated good linearity over the range of 10-2,000 ng/mL for OXC and 5-1,000 ng/mL for MHD. The lower limit of quantification was 5 ng/mL for OXC and 2.5 ng/mL for MHD, respectively. The method was successfully applied to the evaluation of the pharmacokinetics of OXC and MHD in rats, with or without pretreatment by ketoconazole (KET) and voriconazole (VOR). Statistics indicated that KET and VOR significantly affected the disposition of OXC and MHD in vivo, whereas VOR predominantly interfered with the disposition of MHD. This method is suitable for pharmacokinetic study in small animals. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    D.S. Darrow; S.S. Medley; A.L. Roquemore; W.W. Heidbrink; A. Alekseyev; F.E. Cecil; J. Egedal; V.Ya. Goloborod' ko; N.N. Gorelenkov; M. Isobe; S. Kaye; M. Miah; F. Paoletti; M.H. Redi; S.N. Reznik; A. Rosenberg; R. White; D. Wyatt; V.A. Yavorskij

    2002-10-15

    A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the {approx}25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong.

  14. Io's Magnetospheric Interaction: An MHD Model with Day-Night Asymmetry

    Science.gov (United States)

    Kabin, K.; Combi, M. R.; Gombosi, T. I.; DeZeeuw, D. L.; Hansen, K. C.; Powell, K. G.

    2001-01-01

    In this paper we present the results of all improved three-dimensional MHD model for Io's interaction with Jupiter's magnetosphere. We have included the day-night asymmetry into the spatial distribution of our mass-loading, which allowed us to reproduce several smaller features or the Galileo December 1995 data set. The calculation is performed using our newly modified description of the pick-up processes that accounts for the effects of the corotational electric field existing in the Jovian magnetosphere. This change in the formulation of the source terms for the MHD equations resulted in significant improvements in the comparison with the Galileo measurements. We briefly discuss the limitations of our model and possible future improvements.

  15. Generalized MHD for numerical stability analysis of high-performance plasmas in tokamaks

    International Nuclear Information System (INIS)

    Mikhailovskii, A.B.

    1998-01-01

    A set of generalized magnetohydrodynamic (MHD) equations is formulated to accommodate the effects associated with high ion and electron temperatures in high-performance plasmas in tokamaks. The effects of neoclassical bootstrap current, neoclassical ion viscosity, the ion finite Larmor radius effect and electron and ion drift effects are taken into account in two-fluid MHD equations together with gyroviscosity, parallel viscosity, electron parallel inertia and collisionless ion heat flux. The ion velocity is identified as the plasma velocity, while the electron velocity is expressed in terms of the plasma velocity and electric current. Ion and electron momentum equations are combined to give the plasma momentum equation. The perpendicular (with respect to the equilibrium magnetic field) ion momentum equation is used as perpendicular Ohm's law and the parallel electron momentum equation - as parallel Ohm's law. Perpendicular Ohm's law allows for the Hall and ion drift effects. Parallel Ohm's law includes the electron drift effect, collisionless skin effect and bootstrap current. In addition, both perpendicular and parallel Ohm's laws contain the resistivity. Due to the quasineutrality condition, the ions and electrons are characterized by the same number density which is described by the ion continuity equation. On the other hand, the ion and electron temperatures are allowed to be different. The ion temperature is described by the ion energy equation allowing for the oblique heat flux, in addition to the perpendicular ion heat flux. The electron temperature is determined by the condition of high parallel electron heat conductivity. The ion and electron parallel viscosities are represented in a form valid for all the collisionality regimes (Pfirsch-Schluter, plateau, and banana). An optimized form of the generalized MHD equations is then represented in terms of the toroidal coordinate system used in the JET equilibrium and stability codes. The derived equations

  16. Relativistic MHD simulations of stellar core collapse and magnetars

    Energy Technology Data Exchange (ETDEWEB)

    Font, Jose A; Gabler, Michael [Departamento de AstronomIa y Astrofisica, Universitat de Valencia, 46100 Burjassot (Valencia) (Spain); Cerda-Duran, Pablo; Mueller, Ewald [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Stergioulas, Nikolaos, E-mail: j.antonio.font@uv.es [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

    2011-02-01

    We present results from simulations of magneto-rotational stellar core collapse along with Alfven oscillations in magnetars. These simulations are performed with the CoCoA/CoCoNuT code, which is able to handle ideal MHD flows in dynamical spacetimes in general relativity. Our core collapse simulations highlight the importance of genuine magnetic effects, like the magneto-rotational instability, for the dynamics of the flow. For the modelling of magnetars we use the anelastic approximation to general relativistic MHD, which allows for an effective suppression of fluid modes and an accurate description of Alfven waves. We further compute Alfven oscillation frequencies along individual magnetic field lines with a semi-analytic approach. Our work confirms previous results based on perturbative approaches regarding the existence of two families of quasi-periodic oscillations (QPOs), with harmonics at integer multiples of the fundamental frequency. Additional material is presented in the accompanying contribution by Gabler et al (2010b) in these proceedings.

  17. Effect of the X-point on the stability of the edge-current-driven MHD mode in Tokamaks

    International Nuclear Information System (INIS)

    Kwon, Ohjin

    2010-01-01

    Quasi-periodic bursts of edge magnetohydrodynamic (MHD) activities, called edge localized modes (ELMs), have been observed in many tokamaks during the H-mode. The high level of heat and particle transport associated with ELMs may cause serious damage to divertors or plasma facing components. It is therefore important to understand the underlying physics of ELMs. We have numerically investigated the effect of the X-point on the stability of the peeling mode, which is thought to be one of the MHD instabilities responsible for small ELMs. Equilibria with pressure and current profiles, which are unstable to the pure peeling mode for moderately elongated plasma, have been used. The X-point in a diverted plasma has been simulated by introducing of a hump in the plasma boundary. The position, depth and width of the X-point have been varied, and their effect on the stability of the peeling mode has been investigated. We have shown that the peeling mode growth rate decreases as the depth increases. This effect is greater for smaller widths for all positions of the X-point considered. Therefore, a sharper X-point is more efficient in stabilizing the peeling mode. Increasing the depth acts to increase the magnetic shear, the stabilizing effect of which has been shown to have very little dependence on the position or the width of the X-point.

  18. Modeling study on the effects of pulse rise rate in atmospheric pulsed discharges

    Science.gov (United States)

    Zhang, Yuan-Tao; Wang, Yan-Hui

    2018-02-01

    In this paper, we present a modeling study on the discharge characteristics driven by short pulsed voltages, focusing on the effects of pulse rise rate based on the fluid description of atmospheric plasmas. The numerical results show that the breakdown voltage of short pulsed discharge is almost linearly dependent on the pulse rise rate, which is also confirmed by the derived equations from the fluid model. In other words, if the pulse rise rate is fixed as a constant, the simulation results clearly suggest that the breakdown voltage is almost unchanged, although the amplitude of pulsed voltage increases significantly. The spatial distribution of the electric field and electron density are given to reveal the underpinning physics. Additionally, the computational data and the analytical expression also indicate that an increased repetition frequency can effectively decrease the breakdown voltage and current density, which is consistent with the experimental observation.

  19. End region and current consolidation effects upon the performance of an MHD channel for the ETF conceptual design. [Engineering Test Facility

    Science.gov (United States)

    Wang, S. Y.; Smith, J. M.

    1982-01-01

    It is noted that operating conditions which yielded a peak thermodynamic efficiency (41%) for an EFT-size MHD/steam power plant were previously (Wang et al., 1981; Staiger, 1981) identified by considering only the active region (the primary portion for power production) of an MHD channel. These previous efforts are extended here to include an investigation of the effects of the channel end regions on overall power generation. Considering these effects, the peak plant thermodynamic efficiency is found to be slightly lowered (40.7%); the channel operating point for peak efficiency is shifted to the supersonic mode (Mach number of approximately 1.1) rather than the previous subsonic operation (Mach number of approximately 0.9). Also discussed is the sensitivity of the channel performance to the B-field, diffuser recovery coefficient, channel load parameter, Mach number, and combustor pressure.

  20. Interim report on research and development of magnetohydrodynamic (MHD) power generation. General remarks; Denji ryutai (MHD) hatsuden kenkyu kaihatsu chukan hokokusho. Soron

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1973-08-01

    This report covers the MHD power generation research and development project which has been under way for 7 years since fiscal 1966, and contains guidelines to follow in the next 3 years during which studies will continue toward the consummation of the project. Subjected to research and development under this project are the development of superconductive magnets and helium refrigeration/liquefaction equipment, clarification of the power generation characteristics of the 1,000kW-class MHD (magnetohydrodynamic) power generator and of a test machine designed for a long-term operation, etc. Since they contain many basic studies, the efforts are being exerted primarily by the Electrotechnical Laboratory. In the research and development of MHD power generation characteristics, a power generation experiment is conducted through oxygen combustion in a hot wall channel, with the combustor and insulation against the Hall voltage improved. In this test, a maximum output of 1,182kW is achieved under the conditions of a flow rate of 2.9kg/s, a thermal input of 24.6MW, and a flux density of 3.2T. Since there are some problems to solve in connection with the stability of MHD power generation characteristics, durability of the MHD power generation channel, characteristics of heat exchanger system, measures for NOx reduction, etc., some more deliberation is necessary before taking the next research and development step. (NEDO)

  1. Diagnostic development and support of MHD test facilities

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for MHD power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for Heat Recovery/Seed Recovery support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with DIAL's computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel will also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs. 25 figs., 6 tabs.

  2. Diagnostic development and support of MHD test facilities

    International Nuclear Information System (INIS)

    Shepard, W.S.; Cook, R.L.

    1990-01-01

    The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for MHD power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for Heat Recovery/ Seed Recovery support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with DIAL's computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel will also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs

  3. Studies on the crossed flow type MHD turbines

    International Nuclear Information System (INIS)

    Hori, Toshihiro; Katsurai, Makoto

    1981-01-01

    The studies on crossed flow type MHD turbines were performed to improve its characteristics. Two-dimensional models were considered for the analytical studies. To compensate the edge effect of magnetic field, the magnetic field gradient by tapering was considered. An iron-core structure and an air-core structure were investigated. It was found that the ideal characteristics can be obtained when there is the tapered length more than one wave length. Various methods for the improvement of magnetic field were studied in the case of practical crossed flow type MHD turbines. The methods were the adjustment with an iron-core, and the adoption of a curved channel. It can be expected to obtain the internal efficiency of more than 70 percent, when the number of pole-pairs is more than 10 and the radius of curvature of a few times of rotor radius is given to a curved channel. (Kato, T.)

  4. Combustion and Magnetohydrodynamic Processes in Advanced Pulse Detonation Rocket Engines

    Science.gov (United States)

    Cole, Lord Kahil

    A number of promising alternative rocket propulsion concepts have been developed over the past two decades that take advantage of unsteady combustion waves in order to produce thrust. These concepts include the Pulse Detonation Rocket Engine (PDRE), in which repetitive ignition, propagation, and reflection of detonations and shocks can create a high pressure chamber from which gases may be exhausted in a controlled manner. The Pulse Detonation Rocket Induced Magnetohydrodynamic Ejector (PDRIME) is a modification of the basic PDRE concept, developed by Cambier (1998), which has the potential for performance improvements based on magnetohydrodynamic (MHD) thrust augmentation. The PDRIME has the advantage of both low combustion chamber seeding pressure, per the PDRE concept, and efficient energy distribution in the system, per the rocket-induced MHD ejector (RIME) concept of Cole, et al. (1995). In the initial part of this thesis, we explore flow and performance characteristics of different configurations of the PDRIME, assuming quasi-one-dimensional transient flow and global representations of the effects of MHD phenomena on the gas dynamics. By utilizing high-order accurate solvers, we thus are able to investigate the fundamental physical processes associated with the PDRIME and PDRE concepts and identify potentially promising operating regimes. In the second part of this investigation, the detailed coupling of detonations and electric and magnetic fields are explored. First, a one-dimensional spark-ignited detonation with complex reaction kinetics is fully evaluated and the mechanisms for the different instabilities are analyzed. It is found that complex kinetics in addition to sufficient spatial resolution are required to be able to quantify high frequency as well as low frequency detonation instability modes. Armed with this quantitative understanding, we then examine the interaction of a propagating detonation and the applied MHD, both in one-dimensional and two

  5. Advanced optical diagnostics for a coal-fired MHD retrofit of an existing power station

    International Nuclear Information System (INIS)

    Shepard, W.S.; Cook, R.L.

    1990-01-01

    The retrofit concept involves integrating a magnetohydrodynamic (MHD) power generation facility with an existing commercial steam power plant. The MHD power train will be 250 MW t and represents a 5:1 scale-up of existing developmental, proof-of-concept (POC) facilities. The program provides a cost effective way to demonstrate the effectiveness, reliability, and operability of the technology and a basis for future commercialization. An aspect of the program must be to accumulate information on component performance and scale-up relations to enable a smooth transition to commercial plant designs. Special state-of-the-art optical diagnostic instrumentation systems are required for this modern energy conversion technology. In-situ measurements with such systems provide a clearer understanding of the processes involved in the ash/seed-laden MHD gas stream, fundamental scale-up data, performance monitors, and a basis for improved control strategies and control instruments. The types of instrumentation, the measurement locations and frequency, and the benefits for the retrofit program are discussed

  6. Experimental investigation of rotating-drum separators for liquid-metal MHD applications

    International Nuclear Information System (INIS)

    Lenzo, C.S.; Dauzvardis, P.V.; Hantman, R.G.

    1978-01-01

    For the past several years, Argonne National Laboratory has been active in the development of closed-cycle two-phase-flow MHD power systems. One of the key components in such systems is an effective and efficient gas-liquid separator-diffuser. On the basis of an assessment of present technology, it was decided to study the characteristics of a rotating drum type of separator, and a multitask research and development program was initiated within the overall liquid-metal MHD research program. The first task, now completed, centered on the investigation of single-phase flow (liquid) deposited by a flow nozzle on the inner surface of freely-rotating cylinders or drums of 423 mm and 282 mm diam. The tests were designed to study the recovery of energy in the liquid layer deposited on the drum; the torque transmitted to the drum by the liquid as the result of shear stress between the liquid and the drum surface; the characteristics of the liquid layer; and the effects of drum size, nozzle shape and orientation, and nozzle velocity. The test results showed that a stable liquid film was formed on the drum and that the kinetic energy of the liquid layer was high enough to be potentially useful in two-phase-flow MHD power systems

  7. US/USSR cooperative program in open-cycle MHD electrical power gneration. Joint test report No. 2: tests in the U-25B facility; MHD generator test No. 3

    International Nuclear Information System (INIS)

    Tempelmeyer, K.E.; Sokolov, Y.N.

    1979-04-01

    The third joint test with a Soviet U-25B MHD generator and a US superconducting magnet system (SCMS) was conducted in the Soviet U-25B Facility. The primary objectives of the 3rd test were: (1) to operate the facility and MHD channel over a wider range of test parameters, and (2) to study the performance of all components and systems of the flow train at increased mass flow rates of combustion products (up to 4 kg/s), at high magnetic-field induction (up to 5 T), and high values of the electrical field in the MHD generator. The third test has demonstrated that all components and systems of the U-25B facility performed reliably. The electric power generated by the MHD generaor reached a maximum of 575 kW during this test. The MHD generator was operated under electrical loading conditions for 9 hours, and the combustor for a total of approximately 14 hours. Very high Hall fields (2.1 kV/m) were produced in the MHD channel, with a total Hall voltage of 4.24 kV. A detailed description is given of (1) performance of all components and systems of the U-25B facility, (2) analysis of the thermal, gasdynamic, and electrical characteristics of the MHD generator, (3) results of plasma diagnostic studies, (4) studies of vibrational characteristics of the flow train, (5) fluctuation of electrodynamic and gasdynamic parameters, (6) interaction of the MHD generator with the superconducting magnet, and (7) an operational problem, which terminated the test

  8. Evaluation of MHD materials for use in high-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Guidotti, R.

    1978-06-15

    The MHD and high-temperature fuel cell literature was surveyed for data pertaining to materials properties in order to identify materials used in MHD power generation which also might be suitable for component use in high-temperature fuel cells. Classes of MHD-electrode materials evaluated include carbides, nitrides, silicides, borides, composites, and oxides. Y/sub 2/O/sub 3/-stabilized ZrO/sub 2/ used as a reference point to evaluate materials for use in the solid-oxide fuel cell. Physical and chemical properties such as electrical resistivity, coefficient of thermal expansion, and thermodynamic stability toward oxidation were used to screen candidate materials. A number of the non-oxide ceramic MHD-electrode materials appear promising for use in the solid-electrolyte and molten-carbonate fuel cell as anodes or anode constituents. The MHD-insulator materials appear suitable candidates for electrolyte-support tiles in the molten-carbonate fuel cells. The merits and possible problem areas for these applications are discussed and additional needed areas of research are delineated.

  9. The MHD intermediate shock interaction with an intermediate wave: Are intermediate shocks physical?

    International Nuclear Information System (INIS)

    Wu, C.C.

    1988-01-01

    Contrary to the usual belief that MHD intermediate shocks are extraneous, the authors have recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear steepening from a continuous wave. In this paper, he clarifies the differences between the conventional view and the results by studying the interaction of an MHD intermediate shock with an intermediate wave. The study reaffirms his results. In addition, the study shows that there exists a larger class of shocklike solutions in the time-dependent dissiaptive MHD equations than are given by the MHD Rankine-Hugoniot relations. it also suggests a mechanism for forming rotational discontinuities through the interaction of an intermediate shock with an intermediate wave. The results are of importance not only to the MHD shock theory but also to studies such as magnetic field reconnection models

  10. Present state of research and development of MHD power generation

    International Nuclear Information System (INIS)

    Ikeda, Shigeru

    1978-01-01

    MHD power generation can obtain electric energy directly from the heat energy of high speed plasma flow, and the power generating plant of 1 million kW can be realized by this method. When the MHD power generation method is combined before conventional thermal power generation method, the thermal efficiency can be raised to about 60% as compared with 38% in thermal power generation plants. The research and development of MHD power generation are in progress in USA and USSR. The research and development in Japan are in the second stage now after the first stage project for 10 years, and the Mark 7 generator with 100 kW electric output for 200 hr continuous operation is under construction. The MHD power generation is divided into three types according to the conductive fluids used, namely combustion type for thermal power generation, unequilibrated type and liquid metal type for nuclear power generation. The principle of MHD power generation and the constitution of the plant are explained. In Japan, the Mark 2 generator generated 1,180 kW for 1 min in 1971, and the Mark 3 generator generated 1.9 kW continuously for 110 hr in 1967. The MHD generator with superconducting magnet succeeded in 1969 to generate 25 kW for 6 min. The second stage project aimes at collecting design data and obtaining operational experience for the construction of 10 MW class pilot plant, and the Mark 7 and 8 generators are planned. (Kako, I.)

  11. Further analysis of MHD acceleration for a hypersonic wind tunnel

    International Nuclear Information System (INIS)

    Christiansen, M.J.; Schmidt, H.J.; Chapman, J.N.

    1995-01-01

    A previously completed MHD study of the use of an MHD accelerator with seeded air from a state-of-the-art arc heater, was generally hailed as showing that the system studied has some promise of meeting the most critical hypersonic testing requirements. However, some concerns existed about certain aspects of the results. This paper discusses some of these problems and presents analysis of potential solutions. Specifically the problems addressed are; reducing the amount of seed in the flow, reducing test chamber temperatures, and reducing the oxygen dissociation. Modeling techniques are used to study three design variables of the MHD accelerator. The accelerator channel inlet Mach number, the accelerator channel divergence angle, and the magnetic field strength are all studied. These variables are all optimized to meet the goals for seed, temperature, and dissociated oxygen reduction. The results of this paper are encouraging, showing that all three goals can be met. General relationships are observed as to how the design variables affect the performance of the MHD accelerator facility. This paper expands on the results presented in the UTSI report and further supports the feasibility of MHD acceleration as a means to provide hypersonic flight simulation

  12. An innovative method for ideal and resistive MHD stability analysis of tokamaks

    International Nuclear Information System (INIS)

    Tokuda, S.

    2001-01-01

    An advanced asymptotic matching method of ideal and resistive MHD stability analysis in tokamak is reported. The report explains a solution method of two-dimensional Newcomb equation, dispersion relation for an unstable ideal MHD mode in tokamak, and a new scheme for solving resistive MHD inner layer equations as an initial-value problem. (author)

  13. An innovative method for ideal and resistive MHD stability analysis of tokamaks

    International Nuclear Information System (INIS)

    Tokuda, S.

    2001-01-01

    An advanced asymptotic matching method of ideal and resistive MHD stability analysis in tokamaks is reported. A solution method for the two dimensional Newcomb equation, a dispersion relation for an unstable ideal MHD mode in tokamaks and a new scheme for solving resistive MHD inner layer equations as an initial value problem are reported. (author)

  14. Flow-Induced New Channels of Energy Exchange in Multi-Scale Plasma Dynamics - Revisiting Perturbative Hybrid Kinetic-MHD Theory.

    Science.gov (United States)

    Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go

    2016-05-10

    It is found that new channels of energy exchange between macro- and microscopic dynamics exist in plasmas. They are induced by macroscopic plasma flow. This finding is based on the kinetic-magnetohydrodynamic (MHD) theory, which analyses interaction between macroscopic (MHD-scale) motion and microscopic (particle-scale) dynamics. The kinetic-MHD theory is extended to include effects of macroscopic plasma flow self-consistently. The extension is realised by generalising an energy exchange term due to wave-particle resonance, denoted by δ WK. The first extension is generalisation of the particle's Lagrangian, and the second one stems from modification to the particle distribution function due to flow. These extensions lead to a generalised expression of δ WK, which affects the MHD stability of plasmas.

  15. Nonlinear MHD dynamics of tokamak plasmas on multiple time scales

    International Nuclear Information System (INIS)

    Kruger, S.E.; Schnack, D.D.; Brennan, D.P.; Gianakon, T.A.; Sovinec, C.R.

    2003-01-01

    Two types of numerical, nonlinear simulations using the NIMROD code are presented. In the first simulation, we model the disruption occurring in DIII-D discharge 87009 as an ideal MHD instability driven unstable by neutral-beam heating. The mode grows faster than exponential, but on a time scale that is a hybrid of the heating rate and the ideal MHD growth rate as predicted by analytic theory. The second type of simulations, which occur on a much longer time scale, focus on the seeding of tearing modes by sawteeth. Pressure effects play a role both in the exterior region solutions and in the neoclassical drive terms. The results of both simulations are reviewed and their implications for experimental analysis is discussed. (author)

  16. Global MHD modes excited by energetic ions in heliotron/torsatron plasmas

    International Nuclear Information System (INIS)

    Toi, K.; Takechi, M.; Takagi, S.

    1999-01-01

    In the CHS heliotron/torsatron, fishbone instabilities (FBs) and toroidal Alfven eigenmodes(TAEs) are observed for the first time, in NBI heated plasmas where small beam driven current is induced. Pulsed increase in energetic ion loss flux is detected by an escaping ion probe during the m=3/n=2 FBs(m,n:poloidal and toroidal mode numbers). The sawtooth crash is often induced by the m=2/n=1 FBs. The current driven internal kink mode and pressure driven interchange modes are thought to be relevant MHD instabilities to FBs. TAEs with n=1 and n=2 are identified, and localized near the plasma core region where fairly low magnetic shear would be realized by the small net plasma current. So far, the observed TAEs do not lead to enhanced loss of energetic ions because of low magnetic fluctuation level. (author)

  17. Global MHD modes excited by energetic ions in heliotron/torsatron plasmas

    International Nuclear Information System (INIS)

    Toi, K.; Takechi, M.; Takagi, S.

    2001-01-01

    In the CHS heliotron/torsatron, fishbone instabilities (FBs) and toroidal Alfven eigenmodes (TAEs) are observed for the first time, in NBI heated plasmas where small beam driven current is induced. Pulsed increase in energetic ion loss flux is detected by an escaping ion probe during the m=3/n=2 FBs (m,n: poloidal and toroidal mode numbers). The sawtooth crash is often induced by the m=2/n=1 FBs. The current driven internal kink mode and pressure driven interchange modes are thought to be relevant MHD instabilities to FBs. TAEs with n=1 and n=2 are identified, and localized near the plasma core region where fairly low magnetic shear would be realized by the small net plasma current. So far, the observed TAEs do not lead to enhanced loss of energetic ions because of low magnetic fluctuation level. (author)

  18. Simulating solar MHD

    Directory of Open Access Journals (Sweden)

    M. Schüssler

    Full Text Available Two aspects of solar MHD are discussed in relation to the work of the MHD simulation group at KIS. Photospheric magneto-convection, the nonlinear interaction of magnetic field and convection in a strongly stratified, radiating fluid, is a key process of general astrophysical relevance. Comprehensive numerical simulations including radiative transfer have significantly improved our understanding of the processes and have become an important tool for the interpretation of observational data. Examples of field intensification in the solar photosphere ('convective collapse' are shown. The second line of research is concerned with the dynamics of flux tubes in the convection zone, which has far-reaching implications for our understanding of the solar dynamo. Simulations indicate that the field strength in the region where the flux is stored before erupting to form sunspot groups is of the order of 105 G, an order of magnitude larger than previous estimates based on equipartition with the kinetic energy of convective flows.

    Key words. Solar physics · astrophysics and astronomy (photosphere and chromosphere; stellar interiors and dynamo theory; numerical simulation studies.

  19. Empowerment impact assessment (EmpIA), a tool for poverty alleviation and capacity building

    CSIR Research Space (South Africa)

    Louw, MR

    2006-09-01

    Full Text Available their quality of life. xrhombus Facilitate the upgrading of the social and physical environment. xrhombus Increase employment. xrhombus Reduce poverty. xrhombus Stimulate economic growth. xrhombus Reduce imbalances in access to economic opportunities. 1... IMPACT ASSESSMENT (EmpIA), A TOOL FOR POVERTY ALLEVIATION AND CAPACITY BUILDING M.R. LOUW CSIR Built Environment: Pretoria, P.O. Box 395, Pretoria, 0001 ABSTRACT Empowerment impact assessment (EmpIA) is a quantitative...

  20. Bifurcation theory for toroidal MHD instabilities

    International Nuclear Information System (INIS)

    Maschke, E.K.; Morros Tosas, J.; Urquijo, G.

    1992-01-01

    Using a general representation of magneto-hydrodynamics in terms of stream functions and potentials, proposed earlier, a set of reduced MHD equations for the case of toroidal geometry had been derived by an appropriate ordering with respect to the inverse aspect ratio. When all dissipative terms are neglected in this reduced system, it has the same linear stability limits as the full ideal MHD equations, to the order considered. When including resistivity, thermal conductivity and viscosity, we can apply bifurcation theory to investigate nonlinear stationary solution branches related to various instabilities. In particular, we show that a stationary solution of the internal kink type can be found

  1. Modified NASA-Lewis chemical equilibrium code for MHD applications

    Science.gov (United States)

    Sacks, R. A.; Geyer, H. K.; Grammel, S. J.; Doss, E. D.

    1979-01-01

    A substantially modified version of the NASA-Lewis Chemical Equilibrium Code was recently developed. The modifications were designed to extend the power and convenience of the Code as a tool for performing combustor analysis for MHD systems studies. The effect of the programming details is described from a user point of view.

  2. Transient flows in rectangular MHD ducts under the influence of suddenly changing applied magnetic fields

    International Nuclear Information System (INIS)

    Kobayashi, Junichi

    1979-01-01

    The study on the transient flow characteristics in MHD ducts under orthogonal magnetic field is divided into handling two problems: the problem of changing pressure gradient in a uniform orthogonal magnetic field and the problem in which the orthogonal magnetic field itself changes with time. The former has been investigated by many persons, but the latter has not been investigated so often as the former because of its difficulty of handling. In addition, if it is intended to grasp properly the transient flow characteristics in actual MHD ducts, it will be also important that the effects of the electric conductivity of side walls and aspect ratio are clarified. In other words, this paper deals with the problem in which a uniform orthogonal magnetic field is suddenly applied in such manner as Heaviside's step function to or removed from the conductive fluids flowing in sufficiently long rectangular MHD ducts. First, the MHD fundamental equations are described, then they are normalized to give boundary conditions and initial conditions. Next, the transient flow and the derived magnetic field characteristics are numerically analyzed by the difference calculus, and thus the effects of conductor, insulated wall, aspect ratio, Hartmann number, magnetic Prandtl number and others on the above characteristics are clarified. (Wakatsuki, Y.)

  3. Principal characteristics of SFC type MHD generator

    International Nuclear Information System (INIS)

    Kayukawa, Naoyuki; Oikawa, Shun-ichi; Aoki, Yoshiaki; Seidou, Tadashi; Okinaka, Noriyuki

    1988-01-01

    This paper describes the experimental and analytical results obtained for an MHD channel with a two dimensionally shaped magnetic field configuration called 'the SFC-type'. The power generating performance was examined under various load conditions and B-field intensities with a 2 MWt shock tunnel MHD facility. It is demonstrated that the power output performance and the enthalpy extraction scaling law of the conventional uniform B-field MHD generator (UFC-type) were significantly improved by the SFC-design of the spatial distribution of the magnetic field. The arcing processes were also examined by a high speed camera and the post-test observation of arc spot traces on electrodes. Further, the characteristic frequencies of each of the so-called micro and constricted arcs were clarified by spectral analyses. The critical current densities, which define the transient conditions of each from the diffuse-to micro arc, and from the micro-to constricted arc modes could be clearly obtained by the present spectral analysis method. We also investigated the three-dimensional behavior under strong magnetic field based on the coupled electrical and hydrodynamical equations for both of the middle scale SFC-and UFC-type generators. Finally, it is concluded from the above mentioned various aspects that the shaped 2-D magnetic field design will offer a most useful means for the realization of a compact, high efficiency and a long duration open-cycle MHD generator. (author)

  4. Chemical, Biological, and Radiological (CBR) Contamination Survivability: Large Item Interiors

    Science.gov (United States)

    2012-06-22

    CWAs. May cause hardening or swelling of the sealant, which may weaken the seal. Rivet Stainless steel Not expected to have any effect. Not... Electromagnetic Pulse (EMP). TOP 08-2-509 22 June 2012 A-2 APPENDIX A. EXPLANATION OF TERMS. Combat Developer. A category of sponsor...Edgewood Chemical Biological Center EMP electromagnetic pulse FD/SC Failure Definition/Scoring Criteria FM Field Manual FP fluorescent particle

  5. Report on studies on closed cycle MHD power generation; Closed cycle MHD hatsuden kento hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-04-01

    Summarized herein are results of the studies on closed cycle MHD (CCMHD) power generation by the study committee. The studied system is based on the MHD gas turbine combined Brayton cycle of about 500,000 kW in output power, firing natural gas as the fuel, and the conceptual design works therefor are completed. The major findings are: the overall plant efficiency: 54.2% at the power transmission side, plot area required per unit power output: 0.04 m{sup 2}/KW, unit construction cost: 251,000 yen/KW, and unit power generation cost: 10.2 yen/KWh. This system will be more operable than the gas turbine combined cycle with steam system, because start-up time, output change rate, optimum load and so on are constrained not on the power generator side but on the gas turbine side. The expected environmental effects include the exhaust gas NOX concentration being equivalent with that associated with the conventional power generator of 2-stage combustion system, quantity of combustion gases to be treated being approximately 40% of that associated with the gas turbine combined cycle, and reduced CO2 gas emissions, resulting from enhanced power generation efficiency. It is expected that the CCMHD system can exhibit higher efficiency than the high-temperature gas turbine combined cycle system. (NEDO)

  6. Concept for a high performance MHD airbreathing-IEC fusion rocket

    International Nuclear Information System (INIS)

    Froning, H.D. Jr.; Miley, G.H.; Nadler, J.; Shaban, Y.; Momota, H.; Burton, E.

    2001-01-01

    Previous studies have shown that Single-State-to-Orbit (SSTO) vehicle propellant can be reduced by Magnets-Hydro-Dynamic (MHD) processes that minimize airbreathing propulsion losses and propellant consumption during atmospheric flight, and additional reduction in SSTO propellant is enabled by Inertial Electrostatic Confinement (IEC) fusion, whose more energetic reactions reduce rocket propellant needs. MHD airbreathing propulsion during an SSTO vehicle's initial atmospheric flight phase and IEC fusion propulsion during its final exo-atmospheric flight phase is therefore being explored. Accomplished work is not yet sufficient for claiming such a vehicle's feasibility. But takeoff and propellant mass for an MHD airbreathing and IEC fusion vehicle could be as much as 25 and 40 percent less than one with ordinary airbreathing and IEC fusion; and as much as 50 and 70 percent less than SSTO takeoff and propellant mass with MHD airbreathing and chemical rocket propulsion

  7. Concept for a high performance MHD airbreathing-IEC fusion rocket

    Science.gov (United States)

    Froning, H. D.; Miley, G. H.; Nadler, J.; Shaban, Y.; Momota, H.; Burton, E.

    2001-02-01

    Previous studies have shown that Single-State-to-Orbit (SSTO) vehicle propellant can be reduced by Magnets-Hydro-Dynamic (MHD) processes that minimize airbreathing propulsion losses and propellant consumption during atmospheric flight, and additional reduction in SSTO propellant is enabled by Inertial Electrostatic Confinement (IEC) fusion, whose more energetic reactions reduce rocket propellant needs. MHD airbreathing propulsion during an SSTO vehicle's initial atmospheric flight phase and IEC fusion propulsion during its final exo-atmospheric flight phase is therefore being explored. Accomplished work is not yet sufficient for claiming such a vehicle's feasibility. But takeoff and propellant mass for an MHD airbreathing and IEC fusion vehicle could be as much as 25 and 40 percent less than one with ordinary airbreathing and IEC fusion; and as much as 50 and 70 percent less than SSTO takeoff and propellant mass with MHD airbreathing and chemical rocket propulsion. .

  8. 3-D resistive MHD calculations for tokamak plasmas: beyond the simple reduced set of equations

    International Nuclear Information System (INIS)

    Carreras, B.A.; Garcia, L.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.; Masden, B.F.

    1983-01-01

    Numerical studies of the resistive stability of tokamak plasmas in cylindrical geometry have been performed using: (1) the full set of resistive Magnetohydrodynamic (MHD) equations and (2) an extended version of the reduced set of resistive MHD equations including diamagnetic and electron temperature effects. In particular, the nonlinear interaction of tearing modes of many helicities has been investigated. The numerical results confirm many of the features uncovered previously using the simple reduced equations. (author)

  9. Outline of fast analyzer for MHD equilibrium 'FAME'

    International Nuclear Information System (INIS)

    Sakata, Shinya; Haginoya, Hirofumi; Tsuruoka, Takuya; Aoyagi, Tetsuo; Saito, Naoyuki; Harada, Hiroo; Tani, Keiji; Watanabe, Hideto.

    1994-03-01

    The FAME (Fast Analyzer for Magnetohydrodynamic (MHD) Equilibrium) system has been developed in order to provide more than 100 MHD equilibria in time series which are enough for the non-stationary analysis of the experimental data of JT-60 within about 20 minutes shot interval. The FAME is an MIMD type small scale parallel computer with 20 microprocessors which are connected by a multi-stage switching system. The maximum theoretical speed is 250 MFLOPS. For the software system of FAME, MHD equilibrium analysis code SELENE and its input data production code FBI are tuned up taking the parallel processing into consideration. Consequently, the computational performance of the FAME system becomes more than 7 times faster than the existing general purpose computer FACOM M780-10s. This report summarizes the outline of the FAME system including hardware, soft-ware and peripheral equipments. (author)

  10. MHD marking using the MSE polarimeter optics in ILW JET plasmas

    CERN Document Server

    Reyes Cortes, S.; Alves, D.; Baruzzo, M.; Bernardo, J.; Buratti, P.; Coelho, R.; Challis, C.; Chapman, I.; Hawkes, N.; Hender, T.C.; Hobirk, J.; Joffrin, E.

    2016-01-01

    In this communication we propose a novel diagnostic technique, which uses the collection optics of the JET Motional Stark Effect (MSE) diagnostic, to perform polarimetry marking of observed MHD in high temperature plasma regimes. To introduce the technique, first we will present measurements of the coherence between MSE polarimeter, electron cyclotron emission, and Mirnov coil signals aiming to show the feasibility of the method. The next step consists of measuring the amplitude fluctuation of the raw MSE polarimeter signals, for each MSE channel, following carefully the MHD frequency on Mirnov coil data spectrograms. A variety of experimental examples in JET ITER-Like Wall (ILW) plasmas are presented, providing an adequate picture and interpretation for the MSE optics polarimeter technique.

  11. Nonlinear dynamics of single-helicity neoclassical MHD tearing instabilities

    International Nuclear Information System (INIS)

    Spong, D.A.; Shaing, K.C.; Carreras, B.A.; Callen, J.D.; Garcia, L.

    1988-10-01

    Neoclassical magnetohydrodynamic (MHD) effects can significantly alter the nonlinear evolution of resistive tearing instabilities. This is studied numerically by using a flux-surface-averaged set of evolution equations that includes the lowest-order neoclassical MHD effects. The new terms in the equations are fluctuating bootstrap current, neoclassical modification of the resistivity, and neoclassical damping of the vorticity. Single-helicity tearing modes are studied in a cylindrical model over a range of neoclassical viscosities (μ/sub e//ν/sup e/) and values of the Δ' parameter of tearing mode theory. Increasing the neoclassical viscosity leads to increased growth rate and saturated island width as predicted analytically. The larger island width is caused by the fluctuating bootstrap current contribution in Ohm's law. The Δ' parameter no longer solely determines the island width, and finite-width saturated islands may be obtained even when Δ' is negative. The importance of the bootstrap current (/approximately/∂/rho///partial derivative/psi/) in the nonlinear dynamics leads us to examine the sensitivity of the results with respect to different models for the density evolution. 11 refs., 8 figs

  12. Probabilistic approach to EMP assessment

    International Nuclear Information System (INIS)

    Bevensee, R.M.; Cabayan, H.S.; Deadrick, F.J.; Martin, L.C.; Mensing, R.W.

    1980-09-01

    The development of nuclear EMP hardness requirements must account for uncertainties in the environment, in interaction and coupling, and in the susceptibility of subsystems and components. Typical uncertainties of the last two kinds are briefly summarized, and an assessment methodology is outlined, based on a probabilistic approach that encompasses the basic concepts of reliability. It is suggested that statements of survivability be made compatible with system reliability. Validation of the approach taken for simple antenna/circuit systems is performed with experiments and calculations that involve a Transient Electromagnetic Range, numerical antenna modeling, separate device failure data, and a failure analysis computer program

  13. A method for visualizing surface-exposed and internal PfEMP1 adhesion antigens in Plasmodium falciparum infected erythrocytes

    Directory of Open Access Journals (Sweden)

    Arnot David E

    2008-06-01

    Full Text Available Abstract Background The insertion of parasite antigens into the host erythrocyte membrane and the structure and distribution of Plasmodium falciparum adhesion receptors on that membrane are poorly understood. Laser scanning confocal microscopy (LSCM and a novel labelling and fixation method have been used to obtain high resolution immuno-fluorescent images of erythrocyte surface PfEMP1 and internal antigens which allow analysis of the accumulation of PfEMP1 on the erythrocyte membrane during asexual development. Methods A novel staining technique has been developed which permits distinction between erythrocyte surface PfEMP1 and intracellular PfEMP1, in parasites whose nuclear material is exceptionally well resolved. Primary antibody detection by fluorescence is carried out on the live parasitized erythrocyte. The surface labelled cells are then fixed using paraformaldehyde and permeabilized with a non-ionic detergent to permit access of antibodies to internal parasite antigens. Differentiation between surface and internal antigens is achieved using antibodies labelled with different fluorochromes and confocal microscopy Results Surface exposed PfEMP1 is first detectable by antibodies at the trophozoite stage of intracellular parasite development although the improved detection method indicates that there are differences between different laboratory isolates in the kinetics of accumulation of surface-exposed PfEMP1. Conclusion A sensitive method for labelling surface and internal PfEMP1 with up to three different fluorochromes has been developed for laser scanning confocal optical microscopy and the analysis of the developmental expression of malaria adhesion antigens.

  14. Transistor collector breakdown in the presence of conducted EMP and gamma radiation

    International Nuclear Information System (INIS)

    Rice, D.H.

    1975-01-01

    In this paper we develop expressions which describe breakdown, negative resistance and latch characteristics for a common emitter transistor when exposed to simultaneous conducted EMP and ionizing radiation. These expressions are derived from a modified Ebers-Moll model and show that common emitter breakdown voltage is reduced, latch (or sustaining voltage) remains unchanged, and that the negative resistance characteristics are changed. Using the modified Ebers-Moll model good agreement between predicted and observed circuit response is demonstrated when the circuits are exposed to a rising collector voltage (due to EMP) and simultaneous ionizing (gamma) radiation

  15. MHD thrust vectoring of a rocket engine

    Science.gov (United States)

    Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic

    2016-09-01

    In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.

  16. Liquid metal MHD research and development in Israel

    International Nuclear Information System (INIS)

    Branover, H.

    1993-01-01

    The study of liquid metal MHD in Israel commenced in 1973. Initially it was concentrated mainly on laminar flows influenced by external magnetic fields. In 1978 a liquid metal MHD energy conversion program was started. This program was developed at the Center for MHD Studies at Ben-Gurion University in Beer-Sheva, with the participation of specialists from the Technion, the Hebrew University of Jerusalem, Israel Atomic Energy Commission, and others. The program was sponsored initially by the Israel Ministry of Energy and Infrastructure, and later by the Ministry of Industry and Trade. Since 1980, Solmecs, a private commercial company has become a major factor in the development of liquid metal MHD in Israel. From the very beginning the program was based on broad international cooperation. A number of overseas institutions and individuals became participants in the program. Through extensive research and evaluation of a number of concepts of liquid metal MHD power generation systems, It was established that the most promising concept, demanding a relatively short period of development, is the gravitational system using heavy metals (lead, lead alloys) as the magneto-hydrodynamic fluid and steam or gases as thermodynamic fluids. This concept was chosen for further development and industrial application, and the program related to such systems was named the Etgar Program. The main directions of research and development activities have been defined as follows: investigations of physical phenomena, development of universal numerical code for parametric studies, optimization and design of the system, material studies, development of engineering components, building and testing of integrated small-scale Etgar type systems, economic evaluation of the system and comparison with conventional technologies, development of moderate scale industrial demonstration plant. At this time 6 items have been fully implemented and activities on the last item were started. (author)

  17. Study of MHD events initiated by pellet injection into T-10 plasmas

    International Nuclear Information System (INIS)

    Kuteev, B.; Khimchenko, L.; Krylov, S.; Pavlov, Y.; Pustovitov, V.; Sarychev, D.; Sergeev, V.; Skokov, V.; Timokhin, V.

    2005-01-01

    There are several events which might be responsible for ultra fast transport of heat and particles during pellet ablation stage in a tokamak. Those are jumps of transport coefficients, plasma drifts in the pellet vicinity and MHD events with time scale significantly shorter than the pellet ablation time. The role of the latter is still not very well understood due to a lack of studies. This paper is devoted to detailed study of the effects during the pellet ablation phase (∼ one millisecond) with main objective to determine the relation between pellet (material Li, C., KCl, size and velocity) and plasma parameters ( q-value a the pellet position, plasma density and temperature) which initiate microsecond MHD events in plasma. The pellets were injected into both into Ohmic and ECE heated plasmas (up to 3 MW) in the T-10 tokamak at various stages of the plasma discharge, in a wide range from the very beginning up to the post-disruption stage. It is observed that at some conditions a pellet ablates in the plasma without accompanying MHD events. This occurs at the highest plasma densities even if a pellet penetrates through q=1 magnetic surface. The ablation rate corresponds to NGSM in this case. Small scale events may occur near rational magnetic surfaces and the ablation rate fluctuations may be explained by reconnection. Both increase of the longitudinal heat flow due to plasma conventional from higher temperature region and growth of the electric field generation supra-thermal electrons may be responsible for the enhanced ablation. Large scale MHD events envelop a region inside q<3. It is observed that the MHD-cooled area is not poloidally symmetric. Mechanisms of the phenomena observed and their consequences on tokamak operation are discussed. (Author)

  18. Technical support for open-cycle MHD program. Progress report, July--December 1978

    Energy Technology Data Exchange (ETDEWEB)

    Doss, E D [ed.

    1979-06-01

    The support program for open-cycle MHD at Argonne National Laboratory is developing the analytical tools needed to investigate the performance of the major components in the combined cycle MHD/steam power system. The analytical effort is centered on the primary components of the system that are unique to MHD and also on the integration of these analytical representations into a model of the entire power producing system. The present project activities include modeling of the combustor, MHD channel, slag separator, and high-temperature air heater. In addition, these models are combined into a complete system model, which is at present capable of carrying out optimizations of the entire system relative to either thermodynamic efficiency or cost of electrical power. Also, in support of other aspects of the open-cycle program, test plans are developed and facility and program reviews are provided upon request in support of the needs and requirements of the DOE/MHD Division.

  19. MHD-induced Energetic Ion Loss during H-mode Discharges in the National Spherical Torus Experiment (NSTX)

    International Nuclear Information System (INIS)

    Medley, S.S.; Gorelenkov, N.N.; Andre, R.; Bell, R.E.; Darrow, D.S.; Fredrickson, E.D.; Kaye, S.M.; LeBlanc, B.P.; Roquemore, A.L.

    2004-01-01

    MHD-induced energetic ion loss in neutral-beam-heated H-mode [high-confinement mode] discharges in NSTX [National Spherical Torus Experiment] is discussed. A rich variety of energetic ion behavior resulting from magnetohydrodynamic (MHD) activity is observed in the NSTX using a horizontally scanning Neutral Particle Analyzer (NPA) whose sightline views across the three co-injected neutral beams. For example, onset of an n = 2 mode leads to relatively slow decay of the energetic ion population (E ∼ 10-100 keV) and consequently the neutron yield. The effect of reconnection events, sawteeth, and bounce fishbones differs from that observed for low-n, low-frequency, tearing-type MHD modes. In this case, prompt loss of the energetic ion population occurs on a time scale of less than or equal to 1 ms and a precipitous drop in the neutron yield occurs. This paper focuses on MHD-induced ion loss during H-mode operation in NSTX. After H-mode onset, the NPA charge-exchange spectrum usually exhibits a significant loss of energetic ions only for E > E(sub)b/2 where E(sub)b is the beam injection energy. The magnitude of the energetic ion loss was observed to decrease with increasing tangency radius, R(sub)tan, of the NPA sightline, increasing toroidal field, B(sub)T, and increasing neutral-beam injection energy, E(sub)b. TRANSP modeling suggests that MHD-induced ion loss is enhanced during H-mode operation due to an evolution of the q and beam deposition profiles that feeds both passing and trapped ions into the region of low-n MHD activity. ORBIT code analysis of particle interaction with a model magnetic perturbation supported the energy selectivity of the MHD-induced loss observed in the NPA measurements. Transport analysis with the TRANSP code using a fast-ion diffusion tool to emulate the observed MHD-induced energetic ion loss showed significant modifications of the neutral- beam heating as well as the power balance, thermal diffusivities, energy confinement times, and

  20. MHD-induced Energetic Ion Loss during H-mode Discharges in the National Spherical Torus Experiment (NSTX)

    Energy Technology Data Exchange (ETDEWEB)

    S.S. Medley; N.N. Gorelenkov; R. Andre; R.E. Bell; D.S. Darrow; E.D. Fredrickson; S.M. Kaye; B.P. LeBlanc; A.L. Roquemore; and the NSTX Team

    2004-03-15

    MHD-induced energetic ion loss in neutral-beam-heated H-mode [high-confinement mode] discharges in NSTX [National Spherical Torus Experiment] is discussed. A rich variety of energetic ion behavior resulting from magnetohydrodynamic (MHD) activity is observed in the NSTX using a horizontally scanning Neutral Particle Analyzer (NPA) whose sightline views across the three co-injected neutral beams. For example, onset of an n = 2 mode leads to relatively slow decay of the energetic ion population (E {approx} 10-100 keV) and consequently the neutron yield. The effect of reconnection events, sawteeth, and bounce fishbones differs from that observed for low-n, low-frequency, tearing-type MHD modes. In this case, prompt loss of the energetic ion population occurs on a time scale of less than or equal to 1 ms and a precipitous drop in the neutron yield occurs. This paper focuses on MHD-induced ion loss during H-mode operation in NSTX. After H-mode onset, the NPA charge-exchange spectrum usually exhibits a significant loss of energetic ions only for E > E(sub)b/2 where E(sub)b is the beam injection energy. The magnitude of the energetic ion loss was observed to decrease with increasing tangency radius, R(sub)tan, of the NPA sightline, increasing toroidal field, B(sub)T, and increasing neutral-beam injection energy, E(sub)b. TRANSP modeling suggests that MHD-induced ion loss is enhanced during H-mode operation due to an evolution of the q and beam deposition profiles that feeds both passing and trapped ions into the region of low-n MHD activity. ORBIT code analysis of particle interaction with a model magnetic perturbation supported the energy selectivity of the MHD-induced loss observed in the NPA measurements. Transport analysis with the TRANSP code using a fast-ion diffusion tool to emulate the observed MHD-induced energetic ion loss showed significant modifications of the neutral- beam heating as well as the power balance, thermal diffusivities, energy confinement times

  1. The extreme condition analyzing for NEMPI shielding of electronic system in high-intensity pulsed radiation diagnosing

    International Nuclear Information System (INIS)

    Cheng Xiaolei; Liu Fang; Ouyang Xiaoping

    2012-01-01

    The difficulty for estimating the NEMPI (electromagnetic pulsed interference caused by the nuclear reaction) on the electronic system in high-intensity pulsed radiation diagnosing is analyzed in this article. To solve the difficulty, a method called 'Extreme Condition Analyzing' is presented for estimating the NEMPI conservatively and reliably. Through an extreme condition hypothesizing which could be described as 'Entire Coupling of Electric Field Energy', the E max (maximum electric field intensity which could be endured by the electronic system in the high-intensity pulsed radiation) could be figured out without any other information of the EMP caused by the nuclear reaction. Then a feasibility inspection is introduced, to confirm that the EMPI shielding request according to E max is not too extreme to be achieved. (authors)

  2. Interaction of electromagnetic pulse with commercial nuclear-power-plant systems

    Energy Technology Data Exchange (ETDEWEB)

    Ericson, D.M. Jr.; Strawe, D.F.; Sandberg, S.J.; Jones, V.K.; Rensner, G.D.; Shoup, R.W.; Hanson, R.J.; Williams, C.B.

    1983-02-01

    This study examines the interaction of the electromagnetic pulse from a high altitude nuclear burst with commercial nuclear power plant systems. The potential vulnerability of systems required for safe shutdown of a specific nuclear power plant are explored. EMP signal coupling, induced plant response and component damage thresholds are established using techniques developed over several decades under Defense Nuclear Agency sponsorship. A limited test program was conducted to verify the coupling analysis technique as applied to a nuclear power plant. The results are extended, insofar as possible, to other nuclear plants.

  3. Interaction of electromagnetic pulse with commercial nuclear-power-plant systems

    International Nuclear Information System (INIS)

    Ericson, D.M. Jr.; Strawe, D.F.; Sandberg, S.J.; Jones, V.K.; Rensner, G.D.; Shoup, R.W.; Hanson, R.J.; Williams, C.B.

    1983-02-01

    This study examines the interaction of the electromagnetic pulse from a high altitude nuclear burst with commercial nuclear power plant systems. The potential vulnerability of systems required for safe shutdown of a specific nuclear power plant are explored. EMP signal coupling, induced plant response and component damage thresholds are established using techniques developed over several decades under Defense Nuclear Agency sponsorship. A limited test program was conducted to verify the coupling analysis technique as applied to a nuclear power plant. The results are extended, insofar as possible, to other nuclear plants

  4. Stabilities of MHD rotational discontinuities

    International Nuclear Information System (INIS)

    Wang, S.

    1984-11-01

    In this paper, the stabilities of MHD rotational discontinuities are analyzed. The results show that the rotational discontinuities in an incompressible magnetofluid are not always stable with respect to infinitesimal perturbation. The instability condition in a special case is obtained. (author)

  5. MHD stability of tandem mirrors

    International Nuclear Information System (INIS)

    Poulsen, P.; Molvik, A.; Shearer, J.

    1982-01-01

    The TMX-Upgrade experiment was described, and the manner in which various plasma parameters could be affected was discussed. The initial analysis of the MHD stability of the tandem mirror was also discussed, with emphasis on the negative tandem configuration

  6. Safety and reliability in superconducting MHD magnets

    International Nuclear Information System (INIS)

    Laverick, C.; Powell, J.; Hsieh, S.; Reich, M.; Botts, T.; Prodell, A.

    1979-07-01

    This compilation adapts studies on safety and reliability in fusion magnets to similar problems in superconducting MHD magnets. MHD base load magnet requirements have been identified from recent Francis Bitter National Laboratory reports and that of other contracts. Information relevant to this subject in recent base load magnet design reports for AVCO - Everett Research Laboratories and Magnetic Corporation of America is included together with some viewpoints from a BNL workshop on structural analysis needed for superconducting coils in magnetic fusion energy. A summary of design codes used in large bubble chamber magnet design is also included

  7. Effect of Pulse Width on Oxygen-fed Ozonizer

    Science.gov (United States)

    Okada, Sho; Wang, Douyan; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori

    Though general ozonizers based on silent discharge (barrier discharge) have been used to supply ozone at many industrial situations, there is still some problem, such as improvements of ozone yield. In this work, ozone was generated by pulsed discharge in order to improve the characteristics of ozone generation. It is known that a pulse width gives strong effect to the improvement of energy efficiency in exhaust gas processing. In this paper, the effect of pulse duration on ozone generation by pulsed discharge in oxygen would be reported.

  8. A simplified MHD model of capillary Z-Pinch compared with experiments

    Energy Technology Data Exchange (ETDEWEB)

    Shapolov, A.A.; Kiss, M.; Kukhlevsky, S.V. [Institute of Physics, University of Pecs (Hungary)

    2016-11-15

    The most accurate models of the capillary Z-pinches used for excitation of soft X-ray lasers and photolithography XUV sources currently are based on the magnetohydrodynamics theory (MHD). The output of MHD-based models greatly depends on details in the mathematical description, such as initial and boundary conditions, approximations of plasma parameters, etc. Small experimental groups who develop soft X-ray/XUV sources often use the simplest Z-pinch models for analysis of their experimental results, despite of these models are inconsistent with the MHD equations. In the present study, keeping only the essential terms in the MHD equations, we obtained a simplified MHD model of cylindrically symmetric capillary Z-pinch. The model gives accurate results compared to experiments with argon plasmas, and provides simple analysis of temporal evolution of main plasma parameters. The results clarify the influence of viscosity, heat flux and approximations of plasma conductivity on the dynamics of capillary Z-pinch plasmas. The model can be useful for researchers, especially experimentalists, who develop the soft X-ray/XUV sources. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Two-dimensional simulation of the MHD stability, (1)

    International Nuclear Information System (INIS)

    Kurita, Gen-ichi; Amano, Tsuneo.

    1976-03-01

    The two-dimensional computer code has been prepared to study MHD stability of an axisymmetric toroidal plasma with and without the surrounding vacuum region. It also includes the effect of magnetic surfaces with non-circular cross sections. The linearized equations of motion are solved as an initial value problem. The results by computer simulation are compared with those by the theory for the cylindrical plasma; they are in good agreement. (auth.)

  10. MHD stability calculations of high-β quasi-axisymmetric stellarators

    International Nuclear Information System (INIS)

    Fu, G.Y.; Ku, L.P.; Pomphrey, N.; Redi, M.; Kessel, C.; Monticello, D.; Reiman, A.; Hughes, M.; Cooper, W.A.; Nuehrenberg, C.

    2001-01-01

    The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size. (author)

  11. MHD stability calculations of high-β quasi-axisymmetric stellarators

    International Nuclear Information System (INIS)

    Fu, G.Y.; Ku, L.P.; Pomphrey, N.; Redi, M.H.; Kessel, C.; Monticello, D.A.; Reiman, A.; Hughes, M.; Cooper, W.A.; Nuehrenberg, C.

    1999-01-01

    The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size. (author)

  12. MHD Stability Calculations of High-Beta Quasi-Axisymmetric Stellarators

    International Nuclear Information System (INIS)

    Kessel, C.; Fu, G.Y.; Ku, L.P.; Redi, M.H.; Pomphrey, N.

    1999-01-01

    The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size

  13. Nonperturbative measurement of the local magnetic field using pulsed polarimetry for fusion reactor conditions (invited).

    Science.gov (United States)

    Smith, Roger J

    2008-10-01

    A novel diagnostic technique for the remote and nonperturbative sensing of the local magnetic field in reactor relevant plasmas is presented. Pulsed polarimetry [Patent No. 12/150,169 (pending)] combines optical scattering with the Faraday effect. The polarimetric light detection and ranging (LIDAR)-like diagnostic has the potential to be a local B(pol) diagnostic on ITER and can achieve spatial resolutions of millimeters on high energy density (HED) plasmas using existing lasers. The pulsed polarimetry method is based on nonlocal measurements and subtle effects are introduced that are not present in either cw polarimetry or Thomson scattering LIDAR. Important features include the capability of simultaneously measuring local T(e), n(e), and B(parallel) along the line of sight, a resiliency to refractive effects, a short measurement duration providing near instantaneous data in time, and location for real-time feedback and control of magnetohydrodynamic (MHD) instabilities and the realization of a widely applicable internal magnetic field diagnostic for the magnetic fusion energy program. The technique improves for higher n(e)B(parallel) product and higher n(e) and is well suited for diagnosing the transient plasmas in the HED program. Larger devices such as ITER and DEMO are also better suited to the technique, allowing longer pulse lengths and thereby relaxing key technology constraints making pulsed polarimetry a valuable asset for next step devices. The pulsed polarimetry technique is clarified by way of illustration on the ITER tokamak and plasmas within the magnetized target fusion program within present technological means.

  14. Nonperturbative measurement of the local magnetic field using pulsed polarimetry for fusion reactor conditions (invited)

    International Nuclear Information System (INIS)

    Smith, Roger J.

    2008-01-01

    A novel diagnostic technique for the remote and nonperturbative sensing of the local magnetic field in reactor relevant plasmas is presented. Pulsed polarimetry [Patent No. 12/150,169 (pending)] combines optical scattering with the Faraday effect. The polarimetric light detection and ranging (LIDAR)-like diagnostic has the potential to be a local B pol diagnostic on ITER and can achieve spatial resolutions of millimeters on high energy density (HED) plasmas using existing lasers. The pulsed polarimetry method is based on nonlocal measurements and subtle effects are introduced that are not present in either cw polarimetry or Thomson scattering LIDAR. Important features include the capability of simultaneously measuring local T e , n e , and B || along the line of sight, a resiliency to refractive effects, a short measurement duration providing near instantaneous data in time, and location for real-time feedback and control of magnetohydrodynamic (MHD) instabilities and the realization of a widely applicable internal magnetic field diagnostic for the magnetic fusion energy program. The technique improves for higher n e B || product and higher n e and is well suited for diagnosing the transient plasmas in the HED program. Larger devices such as ITER and DEMO are also better suited to the technique, allowing longer pulse lengths and thereby relaxing key technology constraints making pulsed polarimetry a valuable asset for next step devices. The pulsed polarimetry technique is clarified by way of illustration on the ITER tokamak and plasmas within the magnetized target fusion program within present technological means.

  15. Stability analysis of resistive MHD modes via a new numerical matching technique

    International Nuclear Information System (INIS)

    Furukawa, M.; Tokuda, S.; Zheng, L.-J.

    2009-01-01

    Full text: Asymptotic matching technique is one of the principal methods for calculating linear stability of resistive magnetohydrodynamics (MHD) modes such as tearing modes. In applying the asymptotic method, the plasma region is divided into two regions: a thin inner layer around the mode-resonant surface and ideal MHD regions except for the layer. If we try to solve this asymptotic matching problem numerically, we meet practical difficulties. Firstly, the inertia-less ideal MHD equation or the Newcomb equation has a regular singular point at the mode-resonant surface, leading to the so-called big and small solutions. Since the big solution is not square-integrable, it needs sophisticated treatment. Even if such a treatment is applied, the matching data or the ratio of small solution to the big one, has been revealed to be sensitive to local MHD equilibrium accuracy and grid structure at the mode-resonant surface by numerical experiments. Secondly, one of the independent solutions in the inner layer, which should be matched onto the ideal MHD solution, is not square-integrable. The response formalism has been adopted to resolve this problem. In the present paper, we propose a new method for computing the linear stability of resistive MHD modes via matching technique, where the plasma region is divided into ideal MHD regions and an inner region with finite width. The matching technique using an inner region with finite width was recently developed for ideal MHD modes in cylindrical geometry, and good performance was shown. Our method extends this idea to resistive MHD modes. In the inner region, the low-beta reduced MHD equations are solved, and the solution is matched onto the solution of the Newcomb equation by using boundary conditions such that the parallel electric field vanishes properly as approaching the computational boundaries. If we use the inner region with finite width, the practical difficulties raised above can be avoided from the beginning. Figure

  16. MHD repowering of a 250 MWe unit of the TVA Allen Steam Plant

    International Nuclear Information System (INIS)

    Chapman, J.N.; Attig, R.C.

    1992-01-01

    In this paper coal fired MHD repowering is considered for the TVA Allen Steam Plant. The performance of the repowered plant is presented. Cost comparisons are made of the cost of repowering with MHD versus the cost of meeting similar standards by installing scrubbers and selective catalytic NO x reduction (SCNR). For repowering of a single 250 MW e unit, the costs favor scrubbing and SCNR. If one considers a single repowering of all three 250 MW e units by a single MHD topping cycle and boiler, MHD repowering is more economical. Environmental emissions from the repowered plant are estimated

  17. Simulation of the MHD stabilities of the experiment on HL-2A tokamak by GATO code

    International Nuclear Information System (INIS)

    Pan Wei; Chen Liaoyuan; Dong Jiaqi; Shen Yong; Zhang Jinhua

    2009-01-01

    The ideal two-dimensional MHD stabilities code, GATO, has been successfully immigrated to the high-performance computing system of HL-2A and used to the simulation study of the ideal MHD stabilities of the plasmas produced by one of the pellets injection experiments on HL-2A tokamak. The EFIT code was used to reconstruct the equilibrium configures firstly and the GATO was used to compute their MHD stabilities secondly whose source data were obtained by the NO.4050 discharge of the experiments on HL-2A, and finally by analyzing these results the preliminary conclusion was devised that the confinement performance of the plasma was improved because of the stabilization effect of the anti-sheared configures created by the pellets injection. (authors)

  18. The expression of Smad4 after radiation of electromagnetic pulses and apoptosis in spermatogenic cells in mouse

    International Nuclear Information System (INIS)

    Ji Xinxin; Hou Wugang; Zhao Jie; Zhao Yong; Li Wei; Zhang Yuanqiang

    2007-01-01

    The aim of the study was to investigate the relationships between apoptosis induced by radiation of electromagnetic pulses (EMP) and the expression of Smad4 in mouse spermatogenic cells. 40 adult Balb/c mice were used, and 20 were irradiated with whole-body 400kV/m EMP. The mice were sacrificed and specimens were harvested at 1, 7, 14, 21 and 28 days after the irradiation. Histological changes were observed through Hematoxylin-Eosin staining (H-E staining), the apoptosis of spermatogenic cells was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method (TUNEL method) and the Smad4 expression was observed using immunohistochemistry SABC methods. Severe injuries were observed 1 day after the radiation and seminiferous epithelium was mostly recovered 28d after the radiation. The localization of smad4 was significantly different in EMP group compared to the control group, and the expression densities of smad4 decreased significantly at 7, 14 and 21d after irradiation (p<0.05). TUNEL assays demonstrated that there was a significant increase in the mean apoptotic index (AI) in irradiation groups than that of control groups (p<0.01). The results suggested that Smad4 and TGF-13/Smad signal pathway might play an important role in spermatogenic cells apoptosis induced by radiation of EMP. (authors)

  19. Acceleration of the OpenFOAM-based MHD solver using graphics processing units

    International Nuclear Information System (INIS)

    He, Qingyun; Chen, Hongli; Feng, Jingchao

    2015-01-01

    Highlights: • A 3D PISO-MHD was implemented on Kepler-class graphics processing units (GPUs) using CUDA technology. • A consistent and conservative scheme is used in the code which was validated by three basic benchmarks in a rectangular and round ducts. • Parallelized of CPU and GPU acceleration were compared relating to single core CPU in MHD problems and non-MHD problems. • Different preconditions for solving MHD solver were compared and the results showed that AMG method is better for calculations. - Abstract: The pressure-implicit with splitting of operators (PISO) magnetohydrodynamics MHD solver of the couple of Navier–Stokes equations and Maxwell equations was implemented on Kepler-class graphics processing units (GPUs) using the CUDA technology. The solver is developed on open source code OpenFOAM based on consistent and conservative scheme which is suitable for simulating MHD flow under strong magnetic field in fusion liquid metal blanket with structured or unstructured mesh. We verified the validity of the implementation on several standard cases including the benchmark I of Shercliff and Hunt's cases, benchmark II of fully developed circular pipe MHD flow cases and benchmark III of KIT experimental case. Computational performance of the GPU implementation was examined by comparing its double precision run times with those of essentially the same algorithms and meshes. The resulted showed that a GPU (GTX 770) can outperform a server-class 4-core, 8-thread CPU (Intel Core i7-4770k) by a factor of 2 at least.

  20. Acceleration of the OpenFOAM-based MHD solver using graphics processing units

    Energy Technology Data Exchange (ETDEWEB)

    He, Qingyun; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; Feng, Jingchao

    2015-12-15

    Highlights: • A 3D PISO-MHD was implemented on Kepler-class graphics processing units (GPUs) using CUDA technology. • A consistent and conservative scheme is used in the code which was validated by three basic benchmarks in a rectangular and round ducts. • Parallelized of CPU and GPU acceleration were compared relating to single core CPU in MHD problems and non-MHD problems. • Different preconditions for solving MHD solver were compared and the results showed that AMG method is better for calculations. - Abstract: The pressure-implicit with splitting of operators (PISO) magnetohydrodynamics MHD solver of the couple of Navier–Stokes equations and Maxwell equations was implemented on Kepler-class graphics processing units (GPUs) using the CUDA technology. The solver is developed on open source code OpenFOAM based on consistent and conservative scheme which is suitable for simulating MHD flow under strong magnetic field in fusion liquid metal blanket with structured or unstructured mesh. We verified the validity of the implementation on several standard cases including the benchmark I of Shercliff and Hunt's cases, benchmark II of fully developed circular pipe MHD flow cases and benchmark III of KIT experimental case. Computational performance of the GPU implementation was examined by comparing its double precision run times with those of essentially the same algorithms and meshes. The resulted showed that a GPU (GTX 770) can outperform a server-class 4-core, 8-thread CPU (Intel Core i7-4770k) by a factor of 2 at least.

  1. Multimegawatt space nuclear power open-cycle MHD-facility

    International Nuclear Information System (INIS)

    Pavshuk, V.A.; Panchenko, V.P.

    2008-01-01

    Paper presents the results of the efforts to calculate the characteristics, the layout and the engineering design of the open cycle space power propulsion on the basis of the high-temperature nuclear reactor for a nuclear rocket engine and the Faraday 20 MW capacity MHD-generator. The IVG-1 heterogeneous channel-vessel reactor ensuring in the course of the experiments hydrogen heating up to 3100 K, up to 5 MPa pressure at the reactor core outlet, up to 5 kg/s flowsheet, up to 220 MW thermal power served as a reactor is considered. One determined the MHD-generator basic parameters, namely: the portion of Cs dope was equal to 20%, the outlet stagnation pressure - 2 MPa, the electric conductivity - ≅30 S/m, the Mach number - ≅0.7, the magnetic field induction - 6 T, the capacity - 20 MW, the specific power removal - ∼4 MJ/kg. Paper describes the design of the MHD-facility with the working fluid momentless discharge and its basic characteristics [ru

  2. Particle acceleration in regions of magnetic flux emergence: a statistical approach using test-particle- and MHD-simulations

    Science.gov (United States)

    Vlahos, Loukas; Archontis, Vasilis; Isliker, Heinz

    We consider 3D nonlinear MHD simulations of an emerging flux tube, from the convection zone into the corona, focusing on the coronal part of the simulations. We first analyze the statistical nature and spatial structure of the electric field, calculating histograms and making use of iso-contour visualizations. Then test-particle simulations are performed for electrons, in order to study heating and acceleration phenomena, as well as to determine HXR emission. This study is done by comparatively exploring quiet, turbulent explosive, and mildly explosive phases of the MHD simulations. Also, the importance of collisional and relativistic effects is assessed, and the role of the integration time is investigated. Particular aim of this project is to verify the quasi- linear assumptions made in standard transport models, and to identify possible transport effects that cannot be captured with the latter. In order to determine the relation of our results to Fermi acceleration and Fokker-Planck modeling, we determine the standard transport coefficients. After all, we find that the electric field of the MHD simulations must be downscaled in order to prevent an un-physically high degree of acceleration, and the value chosen for the scale factor strongly affects the results. In different MHD time-instances we find heating to take place, and acceleration that depends on the level of MHD turbulence. Also, acceleration appears to be a transient phenomenon, there is a kind of saturation effect, and the parallel dynamics clearly dominate the energetics. The HXR spectra are not yet really compatible with observations, we have though to further explore the scaling of the electric field and the integration times used.

  3. Kinetic analysis of MHD ballooning modes in tokamaks

    International Nuclear Information System (INIS)

    Tang, W.M.; Rewoldt, G.; Cheng, C.Z.; Chance, M.S.

    1984-10-01

    A comprehensive analysis of the stability properties of the appropriate kinetically generalized form of MHD ballooning modes together with the usual trapped-particle drift modes is presented. The calculations are fully electromagnetic and include the complete dynamics associated with compressional ion acoustic waves. Trapped-particle effects along with all forms of collisionless dissipation are taken into account without approximations. The influence of collisions is estimated with a model Krook operator. Results from the application of this analysis to realistic tokamak operating conditions indicate that unstable short-wavelength modes with significant growth rates can extend from β = 0 to value above the upper ideal-MHD-critical-beta associated with the so-called second stability regime. Since the strength of the relevant modes appears to vary gradually with β, these results support a soft beta limit picture involving a continuous (rather than abrupt or hard) modification of anomalous transport already present in low-β-tokamaks. However, at higher beta the increasing dominance of the electromagnetic component of the perturbations indicated by these calculations could also imply significantly different transport scaling properties

  4. Electrode materials for an open-cycle MHD generator channel

    International Nuclear Information System (INIS)

    Telegin, G.P.; Romanov, A.I.; Akopov, F.A.; Gokhshtejn, Ya.P.; Rekov, A.I.

    1983-01-01

    The results of investigations, technological developments and tests of high temperature materials for MHD electrodes on the base of zirconium dioxide, stabilized with oxides of calcium, yttrium, neodymium, and dioxide of cerium, chromites, tamping masses from stabilized dioxide of zirconium, cermets are considered. It is established that binary and ternary solutions on the base of zirconium dioxide and alloyed chromites are the perspective materials for the MHD electrodes on pure fuel

  5. Effect of external circuit on heat transfer in MHD Couette flow

    International Nuclear Information System (INIS)

    Soundalgekar, V.M.

    1982-01-01

    An exact solution of energy equation in fully-developed MHD Coutte flow has been derived. Temperature profiles are shown in open- and short-circuit cases. It has been observed that in short circuit case, temperature and Nusselt number (Nu) increase with increasing M, whereas in open-circuit case, with increasing M, the temperature decreases. Also in open-circuit case, Nu increases with increasing M when M is small, but at large values of M, Nu decreases with increasing M. (author)

  6. The Biermann catastrophe of numerical MHD

    Science.gov (United States)

    Graziani, C.; Tzeferacos, P.; Lee, D.; Lamb, D. Q.; Weide, K.; Fatenejad, M.; Miller, J.

    2016-05-01

    The Biermann Battery effect is frequently invoked in cosmic magnetogenesis and studied in High-Energy Density laboratory physics experiments. Unfortunately, direct implementation of the Biermann effect in MHD codes is known to produce unphysical magnetic fields at shocks whose value does not converge with resolution. We show that this convergence breakdown is due to naive discretization, which fails to account for the fact that discretized irrotational vector fields have spurious solenoidal components that grow without bound near a discontinuity. We show that careful consideration of the kinetics of ion viscous shocks leads to a formulation of the Biermann effect that gives rise to a convergent algorithm. We note a novel physical effect a resistive magnetic precursor in which Biermann-generated field in the shock “leaks” resistively upstream. The effect appears to be potentially observable in experiments at laser facilities.

  7. MHD activity in the ISX-B tokamak: experimental results and theoretical interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, B.A.; Dunlap, J.L.; Bell, J.D.; Charlton, L.A.; Cooper, W.A.; Dory, R.A.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.

    1982-01-01

    The observed spectrum of MHD fluctuations in the ISX-B tokamak is clearly dominated by the n=1 mode when the q=1 surface is in the plasma. This fact agrees well with theoretical predictions based on 3-D resistive MHD calculations. They show that the (m=1; n=1) mode is then the dominant instability. It drives other n=1 modes through toroidal coupling and n>1 modes through nonlinear couplings. These theoretically predicted mode structures have been compared in detail with the experimentally measured wave forms (using arrays of soft x-ray detectors). The agreement is excellent. More detailed comparisons between theory and experiment have required careful reconstructions of the ISX-B equilibria. The equilibria so constructed have permitted a precise evaluation of the ideal MHD stability properties of ISX-B. The present results indicate that the high ..beta.. ISX-B equilibria are marginally stable to finite eta ideal MHD modes. The resistive MHD calculations also show that at finite ..beta.. there are unstable resistive pressure driven modes.

  8. Analysis of the damage threshold of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    International Nuclear Information System (INIS)

    Xi Xiao-Wen; Chai Chang-Chun; Liu Yang; Yang Yin-Tang; Fan Qing-Yang; Shi Chun-Lei

    2016-01-01

    An electromagnetic pulse (EMP)-induced damage model based on the internal damage mechanism of the GaAs pseudomorphic high electron mobility transistor (PHEMT) is established in this paper. With this model, the relationships among the damage power, damage energy, pulse width and signal amplitude are investigated. Simulation results show that the pulse width index from the damage power formula obtained here is higher than that from the empirical formula due to the hotspot transferring in the damage process of the device. It is observed that the damage energy is not a constant, which decreases with the signal amplitude increasing, and then changes little when the signal amplitude reaches up to a certain level. (paper)

  9. Effect of laser pulse energies in laser induced breakdown spectroscopy in double-pulse configuration

    International Nuclear Information System (INIS)

    Benedetti, P.A.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

    2005-01-01

    In this paper, the effect of laser pulse energy on double-pulse laser induced breakdown spectroscopy signal is studied. In particular, the energy of the first pulse has been changed, while the second pulse energy is held fixed. A systematic study of the laser induced breakdown spectroscopy signal dependence on the interpulse delay is performed, and the results are compared with the ones obtained with a single laser pulse of energy corresponding to the sum of the two pulses. At the same time, the crater formed at the target surface is studied by video-confocal microscopy, and the variation in crater dimensions is correlated to the enhancement of the laser induced breakdown spectroscopy signal. The results obtained are consistent with the interpretation of the double-pulse laser induced breakdown spectroscopy signal enhancement in terms of the changes in ambient gas pressure produced by the shock wave induced by the first laser pulse

  10. Compact torus theory: MHD equilibrium and stability

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  11. Technical surveys on MHD combustors. Surveys on incorporation of pressurized coal partial combustion furnaces; MHD combustor gijutsu chosa. Kaatsugata sekitan bubun nenshoro no donyu chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-03-01

    The pressurized coal partial combustion (PCPC) furnace is surveyed/studied for its incorporation in MHD generation. The technical development of the atmospheric CPC has been basically completed, and the concept is demonstrated using a test system of commercial size. Many techniques developed for the atmospheric CPC are applicable to the PCPC system. These include structures of the CPC furnace walls, and slag handling and simulation techniques. Combination of PFBC with PCPC or IGCC can bring about many merits, e.g., enhanced efficiency and abated NOx emissions for the combined cycle power generation. These topping cycles, therefore, should be developed in the early stage. MHD power generation is one of the concepts that can enhance efficiency. In particular, the techniques for closed cycle MHD generation have notably advanced recently. The PCPC techniques are useful for coal combustors for MHD generation. Full-scale development works for the direct coal combustion gas turbine systems have been just started for the IGCC systems of the next generation, and the PCPC-related techniques are expected to serve as the central techniques for these turbine systems. (NEDO)

  12. Computational modeling of neoclassical and resistive MHD tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Gianakon, T.A.; Hegna, C.C.; Callen, J.D.

    1996-01-01

    Numerical studies of the nonlinear evolution of MHD-type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion of neoclassical physics introduces an additional free-energy source for the nonlinear formation of magnetic islands through the effects of a bootstrap current in Ohm's law. The neoclassical tearing mode is demonstrated to be destabilized in plasmas which are otherwise Δ' stable, albeit once an island width threshold is exceeded. The plasma pressure dynamics and neoclassical tearing growth is shown to be sensitive to the choice of the ratio of the parallel to perpendicular diffusivity (Χ parallel/Χ perpendicular). The study is completed with a demonstration and theoretical comparison of the threshold for single helicity neoclassical MHD tearing modes, which is described based on parameter scans of the local pressure gradient, the ratio of perpendicular to parallel pressure diffusivities Χ perpendicular/Χ parallel, and the magnitude of an initial seed magnetic perturbation

  13. Conducting grids to stabilize MHD generator plasmas against ionization instabilities

    International Nuclear Information System (INIS)

    Veefkind, A.

    1972-09-01

    Ionization instabilities in MHD generators may be suppressed by the use of grids that short circuit the AC electric field component corresponding to the direction of maximum growth. An analysis of the influence of the corresponding boundary conditions has been performed in order to obtain more quantitative information about the stabilizing effect of this system

  14. HPC parallel programming model for gyrokinetic MHD simulation

    International Nuclear Information System (INIS)

    Naitou, Hiroshi; Yamada, Yusuke; Tokuda, Shinji; Ishii, Yasutomo; Yagi, Masatoshi

    2011-01-01

    The 3-dimensional gyrokinetic PIC (particle-in-cell) code for MHD simulation, Gpic-MHD, was installed on SR16000 (“Plasma Simulator”), which is a scalar cluster system consisting of 8,192 logical cores. The Gpic-MHD code advances particle and field quantities in time. In order to distribute calculations over large number of logical cores, the total simulation domain in cylindrical geometry was broken up into N DD-r × N DD-z (number of radial decomposition times number of axial decomposition) small domains including approximately the same number of particles. The axial direction was uniformly decomposed, while the radial direction was non-uniformly decomposed. N RP replicas (copies) of each decomposed domain were used (“particle decomposition”). The hybrid parallelization model of multi-threads and multi-processes was employed: threads were parallelized by the auto-parallelization and N DD-r × N DD-z × N RP processes were parallelized by MPI (message-passing interface). The parallelization performance of Gpic-MHD was investigated for the medium size system of N r × N θ × N z = 1025 × 128 × 128 mesh with 4.196 or 8.192 billion particles. The highest speed for the fixed number of logical cores was obtained for two threads, the maximum number of N DD-z , and optimum combination of N DD-r and N RP . The observed optimum speeds demonstrated good scaling up to 8,192 logical cores. (author)

  15. Analytic MHD Theory for Earth's Bow Shock at Low Mach Numbers

    Science.gov (United States)

    Grabbe, Crockett L.; Cairns, Iver H.

    1995-01-01

    A previous MHD theory for the density jump at the Earth's bow shock, which assumed the Alfven M(A) and sonic M(s) Mach numbers are both much greater than 1, is reanalyzed and generalized. It is shown that the MHD jump equation can be analytically solved much more directly using perturbation theory, with the ordering determined by M(A) and M(s), and that the first-order perturbation solution is identical to the solution found in the earlier theory. The second-order perturbation solution is calculated, whereas the earlier approach cannot be used to obtain it. The second-order terms generally are important over most of the range of M(A) and M(s) in the solar wind when the angle theta between the normal to the bow shock and magnetic field is not close to 0 deg or 180 deg (the solutions are symmetric about 90 deg). This new perturbation solution is generally accurate under most solar wind conditions at 1 AU, with the exception of low Mach numbers when theta is close to 90 deg. In this exceptional case the new solution does not improve on the first-order solutions obtained earlier, and the predicted density ratio can vary by 10-20% from the exact numerical MHD solutions. For theta approx. = 90 deg another perturbation solution is derived that predicts the density ratio much more accurately. This second solution is typically accurate for quasi-perpendicular conditions. Taken together, these two analytical solutions are generally accurate for the Earth's bow shock, except in the rare circumstance that M(A) is less than or = 2. MHD and gasdynamic simulations have produced empirical models in which the shock's standoff distance a(s) is linearly related to the density jump ratio X at the subsolar point. Using an empirical relationship between a(s) and X obtained from MHD simulations, a(s) values predicted using the MHD solutions for X are compared with the predictions of phenomenological models commonly used for modeling observational data, and with the predictions of a

  16. Inclusion of pressure and flow in the KITES MHD equilibrium code

    International Nuclear Information System (INIS)

    Raburn, Daniel; Fukuyama, Atsushi

    2013-01-01

    One of the simplest self-consistent models of a plasma is single-fluid magnetohydrodynamic (MHD) equilibrium with no bulk fluid flow under axisymmetry. However, both fluid flow and non-axisymmetric effects can significantly impact plasma equilibrium and confinement properties: in particular, fluid flow can produce profile pedestals, and non-axisymmetric effects can produce islands and stochastic regions. There exist a number of computational codes which are capable of calculating equilibria with arbitrary flow or with non-axisymmetric effects. Previously, a concept for a code to calculate MHD equilibria with flow in non-axisymmetric systems was presented, called the KITES (Kyoto ITerative Equilibrium Solver) code. Since then, many of the computational modules for the KITES code have been completed, and the work-in-progress KITES code has been used to calculate non-axisymmetric force-free equilibria. Additional computational modules are required to allow the KITES code to calculate equilibria with pressure and flow. Here, the authors report on the approaches used in developing these modules and provide a sample calculation with pressure. (author)

  17. High pressure MHD coal combustors investigation, phase 2

    Science.gov (United States)

    Iwata, H.; Hamberg, R.

    1981-05-01

    A high pressure MHD coal combustor was investigated. The purpose was to acquire basic design and support engineering data through systematic combustion experiments at the 10 and 20 thermal megawatt size and to design a 50 MW/sub t/ combustor. This combustor is to produce an electrically conductive plasma generated by the direct combustion of pulverized coal with hot oxygen enriched vitiated air that is seeded with potassium carbonate. Vitiated air and oxygen are used as the oxidizer, however, preheated air will ultimately be used as the oxidizer in coal fired MHD combustors.

  18. The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

    Science.gov (United States)

    Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

    2018-01-01

    Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence

  19. Nonlinear MHD dynamo operating at equipartition

    DEFF Research Database (Denmark)

    Archontis, V.; Dorch, Bertil; Nordlund, Åke

    2007-01-01

    Context.We present results from non linear MHD dynamo experiments with a three-dimensional steady and smooth flow that drives fast dynamo action in the kinematic regime. In the saturation regime, the system yields strong magnetic fields, which undergo transitions between an energy-equipartition a......Context.We present results from non linear MHD dynamo experiments with a three-dimensional steady and smooth flow that drives fast dynamo action in the kinematic regime. In the saturation regime, the system yields strong magnetic fields, which undergo transitions between an energy......, and that it can saturate at a level significantly higher than intermittent turbulent dynamos, namely at energy equipartition, for high values of the magnetic and fluid Reynolds numbers. The equipartition solution however does not remain time-independent during the simulation but exhibits a much more intricate...

  20. New Developments in Modeling MHD Systems on High Performance Computing Architectures

    Science.gov (United States)

    Germaschewski, K.; Raeder, J.; Larson, D. J.; Bhattacharjee, A.

    2009-04-01

    Modeling the wide range of time and length scales present even in fluid models of plasmas like MHD and X-MHD (Extended MHD including two fluid effects like Hall term, electron inertia, electron pressure gradient) is challenging even on state-of-the-art supercomputers. In the last years, HPC capacity has continued to grow exponentially, but at the expense of making the computer systems more and more difficult to program in order to get maximum performance. In this paper, we will present a new approach to managing the complexity caused by the need to write efficient codes: Separating the numerical description of the problem, in our case a discretized right hand side (r.h.s.), from the actual implementation of efficiently evaluating it. An automatic code generator is used to describe the r.h.s. in a quasi-symbolic form while leaving the translation into efficient and parallelized code to a computer program itself. We implemented this approach for OpenGGCM (Open General Geospace Circulation Model), a model of the Earth's magnetosphere, which was accelerated by a factor of three on regular x86 architecture and a factor of 25 on the Cell BE architecture (commonly known for its deployment in Sony's PlayStation 3).

  1. Heat transfer enhancement of free surface MHD-flow by a protrusion wall

    International Nuclear Information System (INIS)

    Hulin Huang; Bo Li

    2010-01-01

    Due to the magnetohydrodynamic (MHD) effect on the flow, which degrades heat transfer coefficients by pulsation suppression of external magnetic field on the flow, a hemispherical protrusion wall is applied to free surface MHD-flow system as a heat transfer enhancement, because the hemispherical protrusion wall has some excellent characteristics including high heat transfer coefficients, low friction factors and high overall thermal performances. So, the characteristics of the fluid flow and heat transfer of the free surface MHD-flow with hemispherical protrusion wall are simulated numerically and the influence of some parameters, such as protrusion height δ/D, and Hartmann number, are also discussed in this paper. It is found that, in the range of Hartmann number 30 ≤ Ha ≤ 70, the protrusion wall assemblies can achieve heat transfer enhancements (Nu/Nu 0 ) of about 1.3-2.3 relative to the smooth channel, while the friction loss (f/f 0 ) increases by about 1.34-1.45. Thus, the high Nusselt number can be obtained when the protrusion wall with a radically lower friction loss increase, which may help get much higher overall thermal performances.

  2. MHD magnet technology development program summary, September 1982

    Energy Technology Data Exchange (ETDEWEB)

    1983-11-01

    The program of MHD magnet technology development conducted for the US Department of Energy by the Massachusetts Institute of Technology during the past five years is summarized. The general strategy is explained, the various parts of the program are described and the results are discussed. Subjects covered include component analysis, research and development aimed at improving the technology base, preparation of reference designs for commercial-scale magnets with associated design evaluations, manufacturability studies and cost estimations, the detail design and procurement of MHD test facility magnets involving transfer of technology to industry, investigations of accessory subsystem characteristics and magnet-flow-train interfacing considerations and the establishment of tentative recommendations for design standards, quality assurance procedures and safety procedures. A systematic approach (framework) developed to aid in the selection of the most suitable commercial-scale magnet designs is presented and the program status as of September 1982 is reported. Recommendations are made for future work needed to complete the design evaluation and selection process and to provide a sound technological base for the detail design and construction of commercial-scale MHD magnets. 85 references.

  3. MHD magnet technology development program summary, September 1982

    International Nuclear Information System (INIS)

    1983-11-01

    The program of MHD magnet technology development conducted for the US Department of Energy by the Massachusetts Institute of Technology during the past five years is summarized. The general strategy is explained, the various parts of the program are described and the results are discussed. Subjects covered include component analysis, research and development aimed at improving the technology base, preparation of reference designs for commercial-scale magnets with associated design evaluations, manufacturability studies and cost estimations, the detail design and procurement of MHD test facility magnets involving transfer of technology to industry, investigations of accessory subsystem characteristics and magnet-flow-train interfacing considerations and the establishment of tentative recommendations for design standards, quality assurance procedures and safety procedures. A systematic approach (framework) developed to aid in the selection of the most suitable commercial-scale magnet designs is presented and the program status as of September 1982 is reported. Recommendations are made for future work needed to complete the design evaluation and selection process and to provide a sound technological base for the detail design and construction of commercial-scale MHD magnets. 85 references

  4. Influence of hot beam ions on MHD ballooning modes in tokamaks

    International Nuclear Information System (INIS)

    Rewoldt, G.; Tang, W.M.

    1984-01-01

    It has recently been proposed that the presence of high-energy ions from neutral-beam injection can have a strong stabilizing effect on kinetically modified ideal-MHD ballooning modes in tokamaks. To assess realistically the importance of such effects, a comprehensive kinetic stability analysis, which takes into account the integral equation nature of the basic problem, has been applied to this investigation. In the collisionless limit, the effect of adding small fractions of hot beam ions is indeed found to be strongly stabilizing. On the other hand, for somewhat larger fractions of hot ions, a different, beam-driven root of the mode equations is found to occur with a growth rate comparable in magnitude to the growth rate of the usual MHD ballooning mode in the absence of hot ions. This implies that there should be an optimal density of hot particles which minimizes the strength of the relevant instabilities. Employing non-Maxwellian equilibrium distribution functions to model the beam species makes a quantitative, but not qualitative, difference in the results. Adding collisions to the calculation tends to reduce considerably the stabilizing effect of the hot ions. (author)

  5. Influence of hot beam ions on MHD ballooning modes in tokamaks

    International Nuclear Information System (INIS)

    Rewoldt, G.; Tang, W.M.

    1984-07-01

    It has recently been proposed that the presence of high energy ions from neutral beam injection can have a strong stabilizing effect on kinetically-modified ideal MHD ballooning modes in tokamaks. In order to assess realistically the importance of such effects, a comprehensive kinetic stability analysis, which takes into account the integral equation nature of the basic problem, has been applied to this investigation. In the collisionless limit, the effect of adding small fractions of hot beam ions is indeed found to be strongly stabilizing. On the other hand, for somewhat larger fractions of hot ions, a new beam-driven mode is found to occur with a growth rate comparable in magnitude to the growth rate of the MHD ballooning mode in the absence of hot ions. This implies that there should be an optimal density of hot particles which minimizes the strength of the relevant instabilities. Employing non-Maxwellian equilibrium distribution functions to model the beam species makes a quantitative, but not qualitative, difference in the results. Adding collisions to the calculation tends to reduce considerably the stabilizing effect of the hot ions

  6. Diagnostics for a coal-fired MHD retrofit of an existing power station

    Energy Technology Data Exchange (ETDEWEB)

    Cook, R L; Shepard, W S [Mississippi State Univ. (USA). Diagnostic Instrumentation and Analysis Lab.

    1990-01-01

    MHD flows represent one of the most severe environments encountered by gasdynamic diagnostics. Special state-of-the-art techniques and instrumentation systems are required to monitor and collect data for the MHD components, and these diagnostic systems must operate under very severe environmental and magnetic field conditions. The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University has developed, and is continuing to develop, advanced optical diagnostic techniques and instrumentation systems to provide nonintrusive, remote real-time measurements and to operate successfully in the industrial-like environment of a large-scale MHD retrofit power station. Such diagnostic instrumentation can provide the information to completely evaluate the performance of individual components, as well as, the entire power plant. It is essential to determine as much detail as possible about the various component operations in an MHD retrofit system so that a commercial plant design can be optimized quickly. This paper discusses the instrumentation systems which DIAL proposed for an MHD retrofit of an existing power station. Instruments which have been making measurements on the U.S. MHD test facilities for several years are presented, along with instruments which will be available within two years. Parameters to be measured along with location and frequency are discussed in detail. These parameters include electron density, electrical conductivity, K-atom density, gas temperature, gas velocity, temperature and velocity profiles, gas composition, and particle size, number, density and distrib00000

  7. Two-dimensional simulation of the MHD stability, (2)

    International Nuclear Information System (INIS)

    Kurita, Gen-ichi; Amano, Tsuneo.

    1977-09-01

    Growth rate and eigen-function of the MHD instability of a toroidal plasma were calculated numerically as an initial-boundary value problem. When a conducting shell is away from the plasma, toroidicity hardly influences growth rate of the external kink modes in a slender tokamak, but it stabilizes the modes in a fat tokamak. On the other hand, when the shell is near to the plasma, the unstable external modes are stabilized by both toroidicity and shell effect. (auth.)

  8. Effects of pulse duration on magnetostimulation thresholds

    International Nuclear Information System (INIS)

    Saritas, Emine U.; Goodwill, Patrick W.; Conolly, Steven M.

    2015-01-01

    Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

  9. Transparência e Replicabilidade na Pesquisa Empírica em Direito: conceitos e ferramentas

    OpenAIRE

    Oliveira, Paulo

    2018-01-01

    Com o crescimento das pesquisas empíricas em Direito quais as práticas devem ser adotadas pelos pesquisadores para acompanhar o Padrão Ouro da pesquisa? Quais os conceitos necessários para que a Pesquisa Empírica possa crescer de forma sustentável e democrática? Esse artigo tenta delinear alguns conceitos importantes da Ciência 2.0 e mostra algumas das principais ferramentas para atingir plenamente o ideal de Ciência Aberta.

  10. Gasdynamic performance in relation to the power extraction of an MHD generator

    International Nuclear Information System (INIS)

    Massee, P.

    1983-01-01

    A study of the gasdynamical processes in MHD generators has been made both theoretically and experimentally. A core flow and boundary layer model has been developed. In order to obtain a fast computer code which can be used for engineering purposes the quasi-one-dimensional approximation is used. It is shown in this thesis that the boundary layers have to be calculated from integral equations describing momentum, kinetic energy and stagnation enthalpy respectively, when the MHD effects in the boundary layers are properly taken into account. Calculations with the developed core flow and boundary layer model have shown that the electrical power output is limited by the design of the existing facility and have indicated possibilities to circumvent this limitation. (Auth.)

  11. MHD simulation of Columbia HBT

    International Nuclear Information System (INIS)

    Li, X.L.

    1987-01-01

    The plasma of Columbia High Beta Tokamak (HBT) is studied numerically by using the two dimensional resistive MHD model. The main object of this work is to understand the high beta formation process of HBT plasma and to compare the simulation with the experiments. 21 refs., 48 figs., 2 tabs

  12. Numerical computation of MHD equilibria

    International Nuclear Information System (INIS)

    Atanasiu, C.V.

    1982-10-01

    A numerical code for a two-dimensional MHD equilibrium computation has been carried out. The code solves the Grad-Shafranov equation in its integral form, for both formulations: the free-boundary problem and the fixed boundary one. Examples of the application of the code to tokamak design are given. (author)

  13. Ion temperature increase during MHD events on the TST-2 spherical tokamak

    International Nuclear Information System (INIS)

    Ejiri, A.; Shiraiwa, S.; Takase, Y.; Yamada, T.; Nagashima, Y.; Kasahara, H.; Iijima, D.; Kobori, Y.; Nishi, T.; Taniguchi, T.; Aramasu, M.; Ohara, S.; Ushigome, M.; Yamagishi, K.

    2003-01-01

    Various types of MHD events including internal reconnection events are studied on the TST-2 spherical tokamak. In weak MHD events no positive current spike was observed, but in strong MHD events with positive current spikes, a rapid and significant impurity ion temperature increase was observed. The decrease in the poloidal magnetic energy is the most probable energy source for ion heating. The plasma current shows a stepwise change. The magnitude of this step correlates with the temperature increase and is found to be a good indicator of the strength of each event. (author)

  14. Intraband effects on ultrafast pulse propagation in semiconductor ...

    Indian Academy of Sciences (India)

    High bit-rate (>10 Gb/s) signals are composed of very short pulses and propagation of such pulses through a semiconductor optical amplifier (SOA) requires consideration of intraband phenomena. Due to the intraband effects, the propagating pulse sees a fast recovering nonlinear gain which introduces less distortion in the ...

  15. Effect of current pulses on Lithium intercalation batteries

    NARCIS (Netherlands)

    Jongh, de P.E.; Notten, P.H.L.

    2002-01-01

    The effect of (dis)charge pulses on lithium-ion batteries is evaluated using an electronic network model. Simulations give insight into the effect of the pulses on the internal processes such as diffusion, migration, electrochemical reactions, heat generation, etc. on time scales from microseconds

  16. Report on evaluation concerning R and D of magneto hydrodynamic (MHD) generation. Introduction; Denji ryutai (MHD) hatsuden no kenkyu kaihatsu ni kansuru hyoka hokokusho. Soron

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1984-03-01

    Evaluation was conducted concerning R and D on magneto hydrodynamic (MHD) generation, with proposals made for the future R and D. As a result of the experimental operation and studies of the Mark 7 machine for MHD generation, a cold wall type generation channel was found promising in the long-term durability under MHD generation conditions. In addition, R and D was conducted on the exhaust gas control system that fulfilled an environmental standard, seed recovery method, grasp of seed coagulation state, etc. The R and D on element technologies were carried out along with the R and D of the Mark 7 and played a role in the backup of its experiment. MHD generation presents a large number of attractive characteristics, with its development expected in the future. However, it seems too early to immediately move on to the next step. Examinations should be made on such matters as comparisons with various kinds of new power generation systems using coal, trends in foreign countries particularly the U-500 project of the Soviet Union, the ideal system for more efficient development, and possibility of international cooperation. (NEDO)

  17. Resonant MHD modes with toroidal coupling

    International Nuclear Information System (INIS)

    Connor, J.W.; Hastie, R.J.; Taylor, J.B.

    1990-07-01

    This is part 2 of a study of resonant perturbations, such as resistive tearing and ballooning modes, in a torus. These are described by marginal ideal mhd equations in the regions between resonant surfaces; matching across these surfaces provides the dispersion relation. In part 1 we described how all the necessary information from the ideal mhd calculations could be represented by a so-called E-matrix. We also described the calculation of this E-matrix for tearing modes (even parity in perturbed magnetic field) in a large aspect ratio torus. There the toroidal modes comprise coupled cylinder tearing modes and the E-matrix is a generalization of the familiar Δ' quantity in a cylinder. In the present paper we discuss resistive ballooning, or twisting-modes, which have odd-parity in perturbed magnetic field. We show that, unlike the tearing modes, these odd-parity modes are instrinsically toroidal and are not directly related to the odd-parity modes in a cylinder. This is evident from the analysis of the high-n limit in ballooning-space, where a transition from a stable Δ' to an unstable Δ' occurs for the twisting mode when the ballooning effect exceeds the interchange effect, which can occur even at large aspect ratio (as in a tokamak). Analysis of the high-n limit in coordinate space, rather than ballooning space, clarifies this singular behaviour and indicates how one may define twisting-mode Δ'. It also yields a prescription for treating low-n twisting modes and a method for calculating an E-matrix for resistive ballooning modes in a large aspect ratio tokamak. The elements of this matrix are given in terms of cylindrical tearing mode solutions

  18. Effect of sequential isoproturon pulse exposure on Scenedesmus vacuolatus.

    Science.gov (United States)

    Vallotton, Nathalie; Eggen, Rik Ilda Lambertus; Chèvre, Nathalie

    2009-04-01

    Aquatic organisms are typically exposed to fluctuating concentrations of herbicides in streams. To assess the effects on algae of repeated peak exposure to the herbicide isoproturon, we subjected the alga Scenedesmus vacuolatus to two sequential pulse exposure scenarios. Effects on growth and on the inhibition of the effective quantum yield of photosystem II (PSII) were measured. In the first scenario, algae were exposed to short, 5-h pulses at high isoproturon concentrations (400 and 1000 microg/l), each followed by a recovery period of 18 h, while the second scenario consisted of 22.5-h pulses at lower concentrations (60 and 120 microg/l), alternating with short recovery periods (1.5 h). In addition, any changes in the sensitivity of the algae to isoproturon following sequential pulses were examined by determining the growth rate-EC(50) prior to and following exposure. In both exposure scenarios, we found that algal growth and its effective quantum yield were systematically inhibited during the exposures and that these effects were reversible. Sequential pulses to isoproturon could be considered a sequence of independent events. Nevertheless, a consequence of inhibited growth during the repeated exposures is the cumulative decrease in biomass production. Furthermore, in the second scenario, when the sequence of long pulses began to approach a scenario of continuous exposure, a slight increase in the tolerance of the algae to isoproturon was observed. These findings indicated that sequential pulses do affect algae during each pulse exposure, even if algae recover between the exposures. These observations could support an improved risk assessment of fluctuating exposures to reversibly acting herbicides.

  19. Effects of pulse duration on magnetostimulation thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Saritas, Emine U., E-mail: saritas@ee.bilkent.edu.tr [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, Ankara 06800 (Turkey); National Magnetic Resonance Research Center (UMRAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Goodwill, Patrick W. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Conolly, Steven M. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of EECS, University of California, Berkeley, California 94720-1762 (United States)

    2015-06-15

    Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

  20. Linear MHD stability analysis of post-disruption plasmas in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Aleynikova, K., E-mail: ksenia.aleynikova@gmail.com [EURATOM Association, Max-Planck-Institut für Plasmaphysik (Germany); Huijsmans, G. T. A. [ITER Organization (France); Aleynikov, P. [EURATOM Association, Max-Planck-Institut für Plasmaphysik (Germany)

    2016-05-15

    Most of the plasma current can be replaced by a runaway electron (RE) current during plasma disruptions in ITER. In this case the post-disruption plasma current profile is likely to be more peaked than the pre-disruption profile. The MHD activity of such plasma will affect the runaway electron generation and confinement and the dynamics of the plasma position evolution (Vertical Displacement Event), limiting the timeframe for runaway electrons and disruption mitigation. In the present paper, we evaluate the influence of the possible RE seed current parameters on the onset of the MHD instabilities. By varying the RE seed current profile, we search for subsequent plasma evolutions with the highest and the lowest MHD activity. This information can be applied to a development of desirable ITER disruption scenario.

  1. Nonlinear evolution of MHD instabilities

    International Nuclear Information System (INIS)

    Bateman, G.; Hicks, H.R.; Wooten, J.W.; Dory, R.A.

    1975-01-01

    A 3-D nonlinear MHD computer code was used to study the time evolution of internal instabilities. Velocity vortex cells are observed to persist into the nonlinear evolution. Pressure and density profiles convect around these cells for a weak localized instability, or convect into the wall for a strong instability. (U.S.)

  2. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments

    National Research Council Canada - National Science Library

    Wilson, Clay

    2004-01-01

    .... civilian computer systems to the effects of EMP has been discussed in the media. EMP can be produced on a large scale using a single nuclear explosion, and on a smaller, non-nuclear scale using a device with batteries or chemical explosives...

  3. MHD studies in FTU plasmas with low and negative magnetic shear

    International Nuclear Information System (INIS)

    Buratti, P.; Alladio, F.; Bracco, G.

    1999-01-01

    Fast current ramps with central ECRH and pellet injection in ohmic plasmas allowed to study several kinds of MHD instabilities in plasmas with peaked pressure profile and low or negative magnetic shear. Double tearing modes were systematically observed when the minimum q value crossed the q min =2 value; such modes either ended into full core reconnection, or saturated at a large amplitude, with a displacement involving more than one third of the plasma radius. Macroscopic fluctuations clamp the peak temperature during central ECRH; the cause of such fluctuations is attributed to MHD modes that are excited when q min is close to a low order rational value; gaps in the distribution of such values can explain the effective transport barriers observed near integer q min values. When q min ∼1 either sawteeth or saturated internal kink modes are observed. (author)

  4. Observation of finite-β MHD phenomena in Tokamaks

    International Nuclear Information System (INIS)

    McGuire, K.M.

    1985-01-01

    Stable high beta plasmas are required for the tokamak to attain an economical fusion reactor. Recently, intense neutral beam heating experiments in tokamaks have shown new effects on plasma stability and confinement associated with high beta plasmas. The observed spectrum of MHD fluctuations at high beta is clearly dominated by the n = 1 mode when the q = 1 surface is in the plasma. The m/n = 1/1 mode drives other n = 1 modes through toroidal coupling and n > 1 modes through nonlinear coupling. On PDX, with near perpendicular injection, a resonant interaction between the n = 1 internal kink and the trapped fast ions results in loss of beam particles and heating power. Key parameters in the theory are the value of qsub(o) and the injection angle. High frequency broadband magnetic fluctuations have been observed on ISX-B and D-III and a correlation with the deterioration of plasma confinement was reported. During enhanced confinement (H-mode) discharges in divertor plasmas two new edge instabilities were observed, both localized radially near the separatrix. By assembling results from the different tokamak experiments, it is found that the simple theoretical ideal MHD beta limit has not been exceeded

  5. Summary and evaluation of the conceptual design study of a potential early commercial MHD power plant (CSPEC)

    Science.gov (United States)

    Staiger, P. J.; Penko, P. F.

    1982-01-01

    The conceptual design study of a potential early commercial MHD power plant (CSPEC) is described and the results are summarized. Each of two contractors did a conceptual design of an approximtely 1000 MWe open-cycle MHD/steam plant with oxygen enriched combustion air preheated to an intermediate temperatue in a metallic heat exchanger. The contractors were close in their overall plant efficiency estimates but differed in their capital cost and cost of electricity estimates, primarily because of differences in balance-of-plant material, contingency, and operating and maintenance cost estimates. One contractor concluded that its MHD plant design compared favorably in cost of electricity with conventional coal-fired steam plants. The other contractor is making such a comparison as part of a follow-on study. Each contractor did a preliminary investigation of part-load performance and plant availability. The results of NASA studies investigating the effect of plant size and oxidizer preheat temperature on the performance of CSPEC-type MHD plants are also described. The efficiency of a 1000 MWe plant is about three points higher than of a 200 MWe plant. Preheating to 1600 F gives an efficiency about one and one-half points higher than preheating to 800 F for all plant sizes. For each plant size and preheat temperature there is an oxidizer enrichment level and MHD generator length that gives the highest plant efficiency.

  6. Principles and techniques of radiation hardening. Volume 2. Transient radiation effects in electronics (TREE)

    International Nuclear Information System (INIS)

    Rudie, N.J.

    1976-01-01

    The three-volume book is intended to serve as a review of the effects of thermonuclear explosion induced radiation (x-rays, gamma rays, and beta particles) and the resulting electromagnetic pulse (EMP). Volume 2 deals with the following topics: radiation effects on quartz crystals, tantalum capacitors, bipolar semiconductor devices and integrated circuits, field effect transistors, and miscellaneous electronic devices; hardening electronic systems to photon and neutron radiation; nuclear radiation source and/or effects simulation techniques; and radiation dosimetry

  7. Vessel calibre and haemoglobin effects on pulse oximetry

    International Nuclear Information System (INIS)

    McEwen, M P; Reynolds, K J; Bull, G P

    2009-01-01

    Despite its success as a clinical monitoring tool, pulse oximetry may be improved with respect to the need for empirical calibration and the reports of biases in readings associated with peripheral vasoconstriction and haemoglobin concentration. To effect this improvement, this work aims to improve the understanding of the photoplethysmography signal—as used by pulse oximeters—and investigates the effect of vessel calibre and haemoglobin concentration on pulse oximetry. The digital temperature and the transmission of a wide spectrum of light through the fingers of 57 people with known haemoglobin concentrations were measured and simulations of the transmission of that spectrum of light through finger models were performed. Ratios of pulsatile attenuations of light as used in pulse oximetry were dependent upon peripheral temperature and on blood haemoglobin concentration. In addition, both the simulation and in vivo results showed that the pulsatile attenuation of light through fingers was approximately proportional to the absorption coefficients of blood, only when the absorption coefficients were small. These findings were explained in terms of discrete blood vessels acting as barriers to light transmission through tissue. Due to the influence of discrete blood vessels on light transmission, pulse oximeter outputs tend to be dependent upon haemoglobin concentration and on the calibre of pulsing blood vessels—which are affected by vasoconstriction/vasodilation. The effects of discrete blood vessels may account for part of the difference between the Beer–Lambert pulse oximetry model and empirical calibration

  8. 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.

  9. Effects of pulsed dual-ion irradiation of microstructural development

    International Nuclear Information System (INIS)

    Packan, N.H.

    1981-01-01

    The effect of pulsed irradiation on the development of microstructure during Ni ion bombardment has been investigated in a simple austenitic alloy similar to type 316 stainless steel. Bombardment conditions were 10 dpa, 940 K, pulsing with equal on/off times of either 0.5 or 60 s, and the addition of 20 appM He/dpa to some specimens either by room temperature preimplantation or by dual-beam coimplantation. Particular care was taken to minimize thermal pulses from beam heating (to 0 C). The results show that pulsing has a subtle influence, and the effects on specific cavity parameters are complex. Pulsing produced a small increase in swelling in the helium-free case, but a slight decrease for helium-implanted specimens, and it seems to have counteracted the usual stimulative effects of helium on cavity nucleation

  10. MHD analysis of high (βt) disruptions in PBX

    International Nuclear Information System (INIS)

    Jahns, G.L.; Chance, M.S.; Kaye, S.M.; Manickam, J.; Takahashi, H.; LeBlanc, B.; Morris, A.W.; Reusch, M.; Sesnic, S.

    1988-01-01

    Princeton Beta Experiment (PBX) discharges run at the lowest q and highest (β t ) always terminated in a hard disruption. The discharges, with (β t ) values of up to 5.5% and q-values down to 2.2, were obtained by employing large current ramps and large gas feed rates during neutral beam injection. Previous work has indicated that the achieved (β t ) values were consistent with the limit imposed by the n=1 ideal external kink with a conducting wall at b/a=2. The authors of the paper investigate further the validity of ideal MHD theory in explaining the low q ψ disruptions. In particular, the characteristics of the pre-disruption MHD activity in these low-q discharges, specifically the time-scale of growth and internal and external mode structures, are compared with those determined from theoretical calculations. The results of these comparisons indicate that non-ideal effects must be considered in order to obtain detailed agreement between theory and experiment. (author). 13 refs, 6 figs

  11. Ideal and resistive MHD stability of internal kink modes in circular and shaped tokamaks

    International Nuclear Information System (INIS)

    Bondeson, A.; Luetjens, H.; Vlad, G.

    1992-01-01

    Recent results for the MHD stability of internal kink modes in tokamaks are reviewed. In general, ideal stability is more restrictive than the conventionally cited limit β p p is the poloidal beta at the q = 1 surface). This holds, in particular, for shaped equilibria, where low shear in combination with elliptic shaping can drastically reduce the pressure limit. Also in resistive MHD, interchange effects are frequently destabilizing, and resistive stability at β p ≥0.05 is achieved, for circular section, only with a very restricted class of current profiles, and not at all for JET-shaped cross section. (author) 9 figs., 24 refs

  12. Application of Fourier transform to MHD flow over an accelerated plate with partial-slippage

    Directory of Open Access Journals (Sweden)

    Salman Ahmad

    2014-06-01

    Full Text Available Magneto-Hydrodynamic (MHD flow over an accelerated plate is investigated with partial slip conditions. Generalized Fourier Transform is used to get the exact solution not only for uniform acceleration but also for variable acceleration. The numerical solution is obtained by using linear finite element method in space and One-Step-θ-scheme in time. The resulting discretized algebraic systems are solved by applying geometric-multigrid approach. Numerical solutions are compared with the obtained Fourier transform results. Many interesting results related with slippage and MHD effects are discussed in detail through graphical sketches and tables. Application of Dirac-Delta function is one of the main features of present work.

  13. Effects of laser wavelengths and pulse energy ratio on the emission enhancement in dual pulse LIBS

    International Nuclear Information System (INIS)

    Ahmed, Rizwan; Iqbal, Javed; Baig, M Aslam

    2015-01-01

    We present new studies on the effects of laser wavelengths, pulse energy ratio and interpulse delay between two laser pulses in the collinear dual pulse configuration of laser-induced breakdown spectroscopy (LIBS) on an iron sample in air using the fundamental (1064 nm) and the second harmonics (532 nm) of Nd:YAG lasers. In the dual pulse LIBS, an optimum value of interpulse delay with an appropriate combination of laser wavelengths, and laser pulse energy ratio, yields a 30 times signal intensity enhancement in the neutral iron lines as compared with single pulse LIBS. A comparison in the spatial variations of electron temperature along the axis of the plume expansion in single and double pulse LIBS has also been studied. (letter)

  14. Ceramic component for M.H.D electrode

    International Nuclear Information System (INIS)

    Marchant, D.D.; Bates, J.L.

    1980-01-01

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hfsub(x)Insub(y)Asub(z)O 2 where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a rare earth or yttrium. The rare earth may be Yb, Tb, Pr or Ce. The component is suitable for use in the fabrication of MHD electrodes or as the current lead-out portion of a composite electrode with other ceramic components. An MHD electrode comprises a cap of a known ceramic, e.g. stabilised zirconium or hafnium oxide or terbium stabilised hafnium, a current lead-out ceramic according to the invention, and a copper frame. (author)

  15. Ideal MHD stability and characteristics of edge localized modes on CFETR

    Science.gov (United States)

    Li, Ze-Yu; Chan, V. S.; Zhu, Yi-Ren; Jian, Xiang; Chen, Jia-Le; Cheng, Shi-Kui; Zhu, Ping; Xu, Xue-Qiao; Xia, Tian-Yang; Li, Guo-Qiang; Lao, L. L.; Snyder, P. B.; Wang, Xiao-Gang; the CFETR Physics Team

    2018-01-01

    Investigation on the equilibrium operation regime, its ideal magnetohydrodynamics (MHD) stability and edge localized modes (ELM) characteristics is performed for the China Fusion Engineering Test Reactor (CFETR). The CFETR operation regime study starts with a baseline scenario (R  =  5.7 m, B T  =  5 T) derived from multi-code integrated modeling, with key parameters {{β }N},{{β }T},{{β }p} varied to build a systematic database. These parameters, under profile and pedestal constraints, provide the foundation for the engineering design. The long wavelength low-n global ideal MHD stability of the CFETR baseline scenario, including the wall stabilization effect, is evaluated by GATO. It is found that the low-n core modes are stable with a wall at r/a  =  1.2. An investigation of intermediate wavelength ideal MHD modes (peeling ballooning modes) is also carried out by multi-code benchmarking, including GATO, ELITE, BOUT++ and NIMROD. A good agreement is achieved in predicting edge-localized instabilities. Nonlinear behavior of ELMs for the baseline scenario is simulated using BOUT++. A mix of grassy and type I ELMs is identified. When the size and magnetic field of CFETR are increased (R  =  6.6 m, B T  =  6 T), collisionality correspondingly increases and the instability is expected to shift to grassy ELMs.

  16. On Unsteady Three-Dimensional Axisymmetric MHD Nanofluid Flow with Entropy Generation and Thermo-Diffusion Effects on a Non-Linear Stretching Sheet

    Directory of Open Access Journals (Sweden)

    Mohammed Almakki

    2017-07-01

    Full Text Available The entropy generation in unsteady three-dimensional axisymmetric magnetohydrodynamics (MHD nanofluid flow over a non-linearly stretching sheet is investigated. The flow is subject to thermal radiation and a chemical reaction. The conservation equations are solved using the spectral quasi-linearization method. The novelty of the work is in the study of entropy generation in three-dimensional axisymmetric MHD nanofluid and the choice of the spectral quasi-linearization method as the solution method. The effects of Brownian motion and thermophoresis are also taken into account. The nanofluid particle volume fraction on the boundary is passively controlled. The results show that as the Hartmann number increases, both the Nusselt number and the Sherwood number decrease, whereas the skin friction increases. It is further shown that an increase in the thermal radiation parameter corresponds to a decrease in the Nusselt number. Moreover, entropy generation increases with respect to some physical parameters.

  17. Nonlinear Diamagnetic Stabilization of Double Tearing Modes in Cylindrical MHD Simulations

    Science.gov (United States)

    Abbott, Stephen; Germaschewski, Kai

    2014-10-01

    Double tearing modes (DTMs) may occur in reversed-shear tokamak configurations if two nearby rational surfaces couple and begin reconnecting. During the DTM's nonlinear evolution it can enter an ``explosive'' growth phase leading to complete reconnection, making it a possible driver for off-axis sawtooth crashes. Motivated by similarities between this behavior and that of the m = 1 kink-tearing mode in conventional tokamaks we investigate diamagnetic drifts as a possible DTM stabilization mechanism. We extend our previous linear studies of an m = 2 , n = 1 DTM in cylindrical geometry to the fully nonlinear regime using the MHD code MRC-3D. A pressure gradient similar to observed ITB profiles is used, together with Hall physics, to introduce ω* effects. We find the diamagnetic drifts can have a stabilizing effect on the nonlinear DTM through a combination of large scale differential rotation and mechanisms local to the reconnection layer. MRC-3D is an extended MHD code based on the libMRC computational framework. It supports nonuniform grids in curvilinear coordinates with parallel implicit and explicit time integration.

  18. 47 CFR 215.1 - Background.

    Science.gov (United States)

    2010-10-01

    ... POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.1 Background. (a) The nuclear electromagnetic pulse (EMP) is part of the complex environment produced by nuclear explosions. It consists of transient...

  19. Neurocognitive effects after brief pulse and ultrabrief pulse unilateral electroconvulsive therapy for major depression: a review.

    Science.gov (United States)

    Verwijk, Esmée; Comijs, Hannie C; Kok, Rob M; Spaans, Harm-Pieter; Stek, Max L; Scherder, Erik J A

    2012-11-01

    Neurocognitive functioning is well known to be affected after ECT. However quantified data about the severity of the cognitive impairment after ultrabrief pulse and brief pulse ECT are limited, which makes it hard to judge its clinical relevance. To review all prospective studies using right unilateral (ultra) brief pulse index electroconvulsive therapy published up until February 2011 which used at least one instrument for cognitive assessment before and after ECT. The severity and persistence of neurocognitive side effects immediately (one to seven days post ECT), between one and six months and after six months post ECT were assessed by calculating effect sizes using Cohen's d. Ten studies fulfilled the inclusion criteria and provided detailed information to compute effect sizes. The results indicate loss of autobiographical memory and impairment of verbal fluency, anterograde verbal and non-verbal memory immediately after brief pulse RUL ECT. To a lesser extent impairment of working memory and reduced speed of processing is found. Autobiographical memory is the only domain still being impaired between one and six months post ECT, but improved in this period. Verbal fluency normalized to baseline performance between one and six months post ECT whereas anterograde verbal and non-verbal memory normalized or even improved. Speed of processing improved within six months after ECT. Long-term data on these cognitive domains were not available. Based on two of the ten included studies the results suggest that ultrabrief pulse RUL ECT causes less decline in autobiographical and anterograde memory after ECT than brief pulse RUL ECT. This review may be limited because of the small number of included studies and due to unreliable effect sizes. Furthermore, few data were available for non-memory domains and cognitive functioning after six months. Loss of autobiographical memory is still present between one and six months after unilateral brief pulse ECT. Ultrabrief pulse RUL

  20. Macroscopic effects in attosecond pulse generation

    International Nuclear Information System (INIS)

    Ruchon, T; Varju, K; Mansten, E; Swoboda, M; L'Huillier, A; Hauri, C P; Lopez-Martens, R

    2008-01-01

    We examine how the generation and propagation of high-order harmonics in a partly ionized gas medium affect their strength and synchronization. The temporal properties of the resulting attosecond pulses generated in long gas targets can be significantly influenced by macroscopic effects, in particular by the intensity in the medium and the degree of ionization which control the dispersion. Under some conditions, the use of gas targets longer than the absorption length can lead to the generation of compressed attosecond pulses. We show these macroscopic effects experimentally, using a 6 mm-long argon-filled gas cell as the generating medium

  1. Macroscopic effects in attosecond pulse generation

    Energy Technology Data Exchange (ETDEWEB)

    Ruchon, T; Varju, K; Mansten, E; Swoboda, M; L' Huillier, A [Department of Physics, Lund University, PO Box 118, SE-221 00 Lund (Sweden); Hauri, C P; Lopez-Martens, R [Laboratoire d' Optique Appliquee, Ecole Nationale Superieure des Techniques Avancees (ENSTA)-Ecole Polytechnique CNRS UMR 7639, 91761 Palaiseau (France)], E-mail: anne.lhuillier@fysik.lth.se

    2008-02-15

    We examine how the generation and propagation of high-order harmonics in a partly ionized gas medium affect their strength and synchronization. The temporal properties of the resulting attosecond pulses generated in long gas targets can be significantly influenced by macroscopic effects, in particular by the intensity in the medium and the degree of ionization which control the dispersion. Under some conditions, the use of gas targets longer than the absorption length can lead to the generation of compressed attosecond pulses. We show these macroscopic effects experimentally, using a 6 mm-long argon-filled gas cell as the generating medium.

  2. Combining MHD Airbreathing and Fusion Rocket Propulsion for Earth-to-Orbit Flight

    International Nuclear Information System (INIS)

    Froning, H. D. Jr; Yang, Yang; Momota, H.; Burton, E.; Miley, G. H.; Luo, Nie

    2005-01-01

    Previous studies have shown that Single-State-to-Orbit (SSTO) vehicle propellant can be reduced by Magnets-Hydro-Dynamic (MHD) processes that minimize airbreathing propulsion losses and propellant consumption during atmospheric flight. Similarly additional reduction in SSTO propellant is enabled by Inertial Electrostatic Confinement (IEC) fusion, whose more energetic reactions reduce rocket propellant needs. MHD airbreathing propulsion during an SSTO vehicle's initial atmospheric flight phase and IEC fusion propulsion during its final exo-atmospheric flight phase is therefore being explored. Accomplished work is not yet sufficient for claiming such a vehicle's feasibility. But takeoff and propellant mass for an MHD airbreathing and IEC fusion vehicle could be as much as 25 and 40 percent less than one with ordinary airbreathing and IEC fusion; and as much as 50 and 70 percent less than SSTO takeoff and propellant mass with MHD airbreathing and chemical rocket propulsion. Thus this unusual combined cycle engine shows great promise for performance gains beyond contemporary combined-cycle airbreathing engines

  3. Ideal MHD stability analysis of KSTAR target AT mode

    International Nuclear Information System (INIS)

    Yi, S.M.; Kim, J.H.; You, K.I.; Kim, J.Y.

    2009-01-01

    Full text: A main research objective of KSTAR (Korea Superconducting Tokamak Advanced Research) device is to demonstrate the steady-state operation capability of high-performance AT (Advanced Tokamak) mode. To meet this goal, it is critical for KSTAR to have a good MHD stability boundary, particularly against the high-beta ideal instabilities such as the external kink and the ballooning modes. To support this MHD stability KSTAR has been designed to have a strong plasma shape and a close interval between plasma and passive- plate wall. During the conceptual design phase of KSTAR, a preliminary study was performed to estimate the high beta MHD stability limit of KSTAR target AT mode using PEST and VACUUM codes and it was shown that the target AT mode can be stable up to β N ∼ 5 with a well-defined plasma pressure and current profiles. Recently, a new calculation has been performed to estimate the ideal stability limit in various KSTAR operating conditions using DCON code, and it has been observed that there is some difference between the new and old calculation results, particularly in the dependence of the maximum β N value on the toroidal mode number. Here, we thus present a more detailed analysis of the ideal MHD stability limit of KSTAR target AT mode using various codes, which include GATO as well as PEST and DCON, in the comparison of calculation results among the three codes. (author)

  4. MHD dynamo action in space plasmas

    International Nuclear Information System (INIS)

    Faelthammar, C.G.

    1984-05-01

    Electric currents are now recognized to play a major role in the physical process of the Earths magnetosphere as well as in distant astrophysical plasmas. In driving these currents MHD dynamos as well as generators of a thermoelectric nature are important. The primary source of power for the Earths magnetospheric process is the solar wind, which supplies a voltage of the order of 200 kV across the magnetosphere. The direction of the large-scale solar wind electric field varies of many different time scales. The power input to the magnetosphere is closely correlated with the direction of the large-scale solar wind electric field in such a fashion as to mimick the response of a half-wave rectifier with a down-to-dusk conduction direction. Behind this apparently simple response there are complex plasma physical processes that are still very incompletely understood. They are intimately related to auroras, magnetic storms, radiation belts and changes in magnetospheric plasma populations. Similar dynamo actions should occur at other planets having magnetospheres. Recent observations seem to indicate that part of the power input to the Earths magnetosphere comes through MHD dynamo action of a forced plasma flow inside the flanks of the magnetopause and may play a role in other parts of the magnetosphere, too. An example of a cosmical MHD connected to a solid load is the corotating plasma of Jupiters inner magnetosphere, sweeping past the plants inner satelites. In particular the electric currents thereby driven to and from the satellite Io have attracted considerable interest.(author)

  5. Intense Ion Pulses for Radiation Effects Research

    Science.gov (United States)

    2017-04-01

    induction linear accelerator that has been developed to deliver intense, up to 50 nC/pulse/mm2, sub-ns pulses of light ions with kinetic energy up to 1.2...II induction linear accelerator for intense ion beam pulses at Berkeley Lab. Figure 3. Helium current and integrated charge versus time at the...under contracts DE-AC02-205CH11231 and DE-AC52-07NA27344. JOURNAL OF RADIATION EFFECTS, Research and Engineering Vol. 35, No. 1, April 2017 158 INTENSE

  6. 47 CFR 215.0 - Purpose and authority.

    Science.gov (United States)

    2010-10-01

    ... POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.0 Purpose and authority. The purpose of this part is to designate a focal point within the Federal Government for electromagnetic pulse (EMP...

  7. A Riccati solution for the ideal MHD plasma response with applications to real-time stability control

    Science.gov (United States)

    Glasser, Alexander; Kolemen, Egemen; Glasser, A. H.

    2018-03-01

    Active feedback control of ideal MHD stability in a tokamak requires rapid plasma stability analysis. Toward this end, we reformulate the δW stability method with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the generic tokamak ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD matrix Riccati differential equation. Since Riccati equations are prevalent in the control theory literature, such a shift in perspective brings to bear a range of numerical methods that are well-suited to the robust, fast solution of control problems. We discuss the usefulness of Riccati techniques in solving the stiff ordinary differential equations often encountered in ideal MHD stability analyses—for example, in tokamak edge and stellarator physics. We demonstrate the applicability of such methods to an existing 2D ideal MHD stability code—DCON [A. H. Glasser, Phys. Plasmas 23, 072505 (2016)]—enabling its parallel operation in near real-time, with wall-clock time ≪1 s . Such speed may help enable active feedback ideal MHD stability control, especially in tokamak plasmas whose ideal MHD equilibria evolve with inductive timescale τ≳ 1s—as in ITER.

  8. Study on closed cycle MHD generation systems; Closed cycle MHD hatsuden system no kento

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1988-03-01

    The closed cycle noble gas MHD generation systems are surveyed and studied. The concept of closed cycle noble gas MHD generation is confirmed to extract high enthalpy, and now going into the engineering demonstration stage from the basic research stage. These systems have various characteristics. The highest working temperature is around 1,700 degrees C, which is close to that associated with the existing techniques. Use of helium or argon gas as the working fluid makes the system relatively free of various problems, e.g., corrosion. It can attain a much higher efficiency than the combined cycle involving gas turbine. It suffers less heat loss in the passages, is suitable for small- to medium-capacity power generation systems, and copes with varying load. The compact power generation passages decrease required size of the superconducting magnet. The technical problems to be solved include optimization of power generation conditions, demonstration of durability of the power generation passages, injection/recovery of the seed material, treatment of the working gas to remove molecular impurities, and development of heat exchangers serviceable at high temperature produced by direct combustion of coal. The conceptual designs of the triple combined system are completed. (NEDO)

  9. Effects of MHD-activity-induced low-n error magnetic fields on the neoclassical viscosities in helical plasmas

    International Nuclear Information System (INIS)

    Nishimura, Shin

    2009-01-01

    Effects of the perturbed magnetic field with low toroidal mode numbers (n) are considered. One cause of this type of perturbation, which has recently been studied in tokamaks, is MHD-activities. In helical/stellarator, this low-n perturbation is sometimes artificially added for island diverters. In viewpoint of the neoclassical viscosities, these perturbed magnetic fields affect on both of bounce center drifts of toroidally trapped and ripple-trapped particles. However, in usual neoclassical analyses in helical/stellarator devices assuming periodic magnetic field strength, these effects had not been studied. For future studies in helical/stellarator devices, a method to use bounce-averaged drift kinetic equation for the toroidally trapped particles is proposed. (author)

  10. Thermal radiation and mass transfer effects on unsteady MHD free convection flow past a vertical oscillating plate

    Science.gov (United States)

    Rana, B. M. Jewel; Ahmed, Rubel; Ahmmed, S. F.

    2017-06-01

    Unsteady MHD free convection flow past a vertical porous plate in porous medium with radiation, diffusion thermo, thermal diffusion and heat source are analyzed. The governing non-linear, partial differential equations are transformed into dimensionless by using non-dimensional quantities. Then the resultant dimensionless equations are solved numerically by applying an efficient, accurate and conditionally stable finite difference scheme of explicit type with the help of a computer programming language Compaq Visual Fortran. The stability and convergence analysis has been carried out to establish the effect of velocity, temperature, concentration, skin friction, Nusselt number, Sherwood number, stream lines and isotherms line. Finally, the effects of various parameters are presented graphically and discussed qualitatively.

  11. Calculation of magnetic field and electromagnetic forces in MHD superconducting magnets

    International Nuclear Information System (INIS)

    Martinelli, G.; Morini, A.; Moisio, M.F.

    1992-01-01

    The realization of a superconducting prototype magnet for MHD energy conversion is under development in Italy. Electromechanical industries and University research groups are involved in the project. The paper deals with analytical methods developed at the Department of Electrical Engineering of Padova University for calculating magnetic field and electromagnetic forces in MHD superconducting magnets and utilized in the preliminary design of the prototype

  12. Heat effect of pulsed Er:YAG laser radiation

    Science.gov (United States)

    Hibst, Raimund; Keller, Ulrich

    1990-06-01

    Pulsed Er:YAG laser radiation has been found to be effective for dental enamel and dentin removal. Damage to the surrounding hard tissue is little, but before testing the Er:YAG laser clinically for the preparation of cavities, possible effects on the soft tissue of the pulp must be known. In order to estimate pulp damage , temperature rise in dentin caused by the laser radiation was measured by a thermocouple. Additionally, temperature distributions were observed by means of a thermal imaging system. The heat effect of a single Er:YAG laser pulse is little and limited to the vicinity of the impact side. Because heat energy is added with each additional pulse , the temperature distribution depends not only on the radiant energy, but also on the number of pulses and the repetition rate. Both irradiation conditions can be found , making irreversible pulp damage either likely or unlikely. The experimental observations can be explained qualitatively by a simple model of the ablation process.

  13. Feasibility study of a nonequilibrium MHD accelerator concept for hypersonic propulsion ground testing

    International Nuclear Information System (INIS)

    Lee, Ying-Ming; Simmons, G.A.; Nelson, G.L.

    1995-01-01

    A National Aeronautics and Space Administration (NASA) funded research study to evaluate the feasibility of using magnetohydrodynamic (MHD) body force accelerators to produce true air simulation for hypersonic propulsion ground testing is discussed in this paper. Testing over the airbreathing portion of a transatmospheric vehicle (TAV) hypersonic flight regime will require high quality air simulation for actual flight conditions behind a bow shock wave (forebody, pre-inlet region) for flight velocities up to Mach 16 and perhaps beyond. Material limits and chemical dissociation at high temperature limit the simulated flight Mach numbers in conventional facilities to less than Mach 12 for continuous and semi-continuous testing and less than Mach 7 for applications requiring true air chemistry. By adding kinetic energy directly to the flow, MHD accelerators avoid the high temperatures and pressures required in the reservoir region of conventional expansion facilities, allowing MHD to produce true flight conditions in flight regimes impossible with conventional facilities. The present study is intended to resolve some of the critical technical issues related to the operation of MHD at high pressure. Funding has been provided only for the first phase of a three to four year feasibility study that would culminate in the demonstration of MHD acceleration under conditions required to produce true flight conditions behind a bow shock wave to flight Mach numbers of 16 or greater. MHD critical issues and a program plan to resolve these are discussed

  14. Slip effects on MHD flow and heat transfer of ferrofluids over a moving flat plate

    Science.gov (United States)

    Ramli, Norshafira; Ahmad, Syakila; Pop, Ioan

    2017-08-01

    In this study, the problem of MHD flow and heat transfer of ferrofluids over a moving flat plate with slip effect and uniform heat flux is considered. The governing ordinary differential equations are solved via shooting method. The effect of slip parameter on the dimensionless velocity, temperature, skin friction and Nusselt numbers are numerically studied for the three selected ferroparticles; magnetite (Fe3O4), cobalt ferrite (CoFe2O4) and Mn-Zn ferrite (Mn-ZnFe2O4) with water-based fluid. The results indicate that dual solutions exist for a plate moving towards the origin. It is found that the slip process delays the boundary layer separation. Moreover, the velocity and thermal boundary-layer thicknesses decrease in the first solution while increase with the increase of the value of slip parameters in second solution.

  15. A randomized controlled trial of long term effect of BCM guided fluid management in MHD patients (BOCOMO study: rationales and study design

    Directory of Open Access Journals (Sweden)

    Liu Li

    2012-09-01

    that aim, the study was designed with very careful important considerations related to the endpoints, sample size, inclusion criteria, exclusion criteria and so on. For example, annual mortality of Beijing MHD patients was around 10%. To reach statistical significance, the sample size will be very large. By using composite endpoint, the sample size becomes reasonable and feasible. Limiting inclusion to patients with urine volume less than 800 ml/day the day before dialysis session will limit confounding due to residual renal function effects on the measured parameters. Patients who had received BIS measurement within 3 months prior to enrolment are excluded as data from such measurements might lead to protocol violation. Although not all patients enrolled will be incident patients, we will record the vintage of dialysis in the multivariable analysis. Trial registration Current Controlled Trials NCT01509937

  16. Characteristics of Linear MHD Generators with One or a Few Loads

    Energy Technology Data Exchange (ETDEWEB)

    Witalis, E A

    1966-02-15

    The theoretical performance of linear series segmented MHD generators with finite size electrodes and one or a few identical external loads is investigated. The analysis is an extension of our conformal mapping investigation previously reported. The electrical characteristics are evaluated as functions of the segmentation degree, the Hall parameter and the relative position of short-circuited electrodes. Special consideration is given to the influence of staggering the electrodes, i. e. shifting the relative positions of short-circuited electrodes. General electrical terminal characteristics, i. e. the full current-voltage relation, can not be obtained by the exact analytical method, which is applicable only to so-called design load conditions or infinitely long MHD channels. However, it is shown how the general properties can be explained qualitatively and calculated approximately by describing off-design modes of operation in terms of a fictitious 'effective' number of external loads.

  17. Characteristics of Linear MHD Generators with One or a Few Loads

    International Nuclear Information System (INIS)

    Witalis, E.A.

    1966-02-01

    The theoretical performance of linear series segmented MHD generators with finite size electrodes and one or a few identical external loads is investigated. The analysis is an extension of our conformal mapping investigation previously reported. The electrical characteristics are evaluated as functions of the segmentation degree, the Hall parameter and the relative position of short-circuited electrodes. Special consideration is given to the influence of staggering the electrodes, i. e. shifting the relative positions of short-circuited electrodes. General electrical terminal characteristics, i. e. the full current-voltage relation, can not be obtained by the exact analytical method, which is applicable only to so-called design load conditions or infinitely long MHD channels. However, it is shown how the general properties can be explained qualitatively and calculated approximately by describing off-design modes of operation in terms of a fictitious 'effective' number of external loads

  18. Comparison of MHD-induced rotation damping with NTV predictions on MAST

    International Nuclear Information System (INIS)

    Hua, M-D; Chapman, I T; Field, A R; Hastie, R J; Pinches, S D

    2010-01-01

    Plasma rotation in tokamaks is of special interest for its potential stabilizing effect on micro- and macro-instabilities, leading to increased confinement. In MAST, the torque from neutral beam injection can spin the plasma to a core velocity ∼300 km s -1 (Alfven Mach number ∼0.3). Low density plasmas often exhibit a weakly non-monotonic safety factor profile just above unity. Theory predicts that such equilibria are prone to magneto-hydro-dynamic (MHD) instabilities, which was confirmed by recent observations. The appearance of the mode is accompanied by strong damping of core rotation on a timescale much faster than the momentum confinement time. The mode's saturated structure is estimated using the CASTOR code together with soft x-ray measurements, enabling the calculation of the plasma braking by the MHD mode according to neoclassical toroidal viscosity (NTV) theory. The latter exhibits strong similarities with the torque measured experimentally.

  19. Three-dimensional nonlinear ideal MHD equilibria with field-aligned incompressible and compressible flows

    International Nuclear Information System (INIS)

    Moawad, S. M.; Ibrahim, D. A.

    2016-01-01

    The equilibrium properties of three-dimensional ideal magnetohydrodynamics (MHD) are investigated. Incompressible and compressible flows are considered. The governing equations are taken in a steady state such that the magnetic field is parallel to the plasma flow. Equations of stationary equilibrium for both of incompressible and compressible MHD flows are derived and described in a mathematical mode. For incompressible MHD flows, Alfvénic and non-Alfvénic flows with constant and variable magnetofluid density are investigated. For Alfvénic incompressible flows, the general three-dimensional solutions are determined with the aid of two potential functions of the velocity field. For non-Alfvénic incompressible flows, the stationary equilibrium equations are reduced to two differential constraints on the potential functions, flow velocity, magnetofluid density, and the static pressure. Some examples which may be of some relevance to axisymmetric confinement systems are presented. For compressible MHD flows, equations of the stationary equilibrium are derived with the aid of a single potential function of the velocity field. The existence of three-dimensional solutions for these MHD flows is investigated. Several classes of three-dimensional exact solutions for several cases of nonlinear equilibrium equations are presented.

  20. Solar furnace experiments for thermophysical properties studies of rare-earth oxide MHD materials

    International Nuclear Information System (INIS)

    Coutures, J.P.

    1978-01-01

    Some high temperature work performed with solar furnaces on rare earth oxides is reviewed. Emphasis is on the thermophysical properties (refractoriness, vaporization behavior) and the nature of solid solution on materials which could be used as electrodes for the MHD process. As new sources of energy are being developed due to the world energy crisis, MHD conversion could be useful. The development of MHD systems requires new efforts to develop and optimize materials properties. These materials must have good mechanical and electrical properties (if possible, pure electronic conduction with good emission). Because of the high temperature in MHD generators, the materials for electrodes must have good refractoriness and also must resist vaporization and corrosion at high temperature (T approx. 2000 0 C). Rare-earth oxides are the basic components for most of the MHD electrode materials and it is important to know their thermophysical properties (solidification point phase transitions, heat of fusion and of phase transition, vapor pressure). Because of the high temperature range and the nature of the atmosphere in which these experiments must be performed, special equipment adapted to solar furnaces was developed

  1. Recent progress on MHD-induced loss of D-D fusion products in TFTR

    International Nuclear Information System (INIS)

    Zweben, S.J.; Darrow, D.S.; Budny, R.V.; Cheng, C.Z.; Fredrickson, E.D.; Herrmann, H.; Mynick, H.E.; Schivell, J.

    1993-08-01

    This paper reviews the recent progress made toward understanding the MHD-induced loss of D-D fusion products which has been seen on TFTR since 1988. These measurements have been made using the ''lost alpha'' diagnostic, which is described briefly. The largest MHD- induced loss occurs with coherent 3/2 or 2/1 MHD activity (kink/tearing modes), which can cause up to ∼3--5 times the first-orbit loss at I∼1.6--1.8 MA, roughly a ∼20--30% global los of D-D fusion products. Modeling of these MHD-induced losses has progressed to the point where the basic loss mechanism can be accounted for qualitatively, but the experimental results can not yet be understood quantitatively. Several alpha loss codes are being developed to improve the quantitative comparison between experiment and theory

  2. Disappearance of Anisotropic Intermittency in Large-amplitude MHD Turbulence and Its Comparison with Small-amplitude MHD Turbulence

    Science.gov (United States)

    Yang, Liping; Zhang, Lei; He, Jiansen; Tu, Chuanyi; Li, Shengtai; Wang, Xin; Wang, Linghua

    2018-03-01

    Multi-order structure functions in the solar wind are reported to display a monofractal scaling when sampled parallel to the local magnetic field and a multifractal scaling when measured perpendicularly. Whether and to what extent will the scaling anisotropy be weakened by the enhancement of turbulence amplitude relative to the background magnetic strength? In this study, based on two runs of the magnetohydrodynamic (MHD) turbulence simulation with different relative levels of turbulence amplitude, we investigate and compare the scaling of multi-order magnetic structure functions and magnetic probability distribution functions (PDFs) as well as their dependence on the direction of the local field. The numerical results show that for the case of large-amplitude MHD turbulence, the multi-order structure functions display a multifractal scaling at all angles to the local magnetic field, with PDFs deviating significantly from the Gaussian distribution and a flatness larger than 3 at all angles. In contrast, for the case of small-amplitude MHD turbulence, the multi-order structure functions and PDFs have different features in the quasi-parallel and quasi-perpendicular directions: a monofractal scaling and Gaussian-like distribution in the former, and a conversion of a monofractal scaling and Gaussian-like distribution into a multifractal scaling and non-Gaussian tail distribution in the latter. These results hint that when intermittencies are abundant and intense, the multifractal scaling in the structure functions can appear even if it is in the quasi-parallel direction; otherwise, the monofractal scaling in the structure functions remains even if it is in the quasi-perpendicular direction.

  3. MHD stability limits in the TCV Tokamak

    International Nuclear Information System (INIS)

    Reimerdes, H.

    2001-07-01

    Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak a Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field, which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuations. A spatially dense set of magnetic probes, installed inside the TCV vacuum vessel, allows for a fast observation of these fluctuations. The structure and temporal evolution of coherent modes is extracted using several numerical methods. In addition to the setup of the magnetic diagnostic and the implementation of analysis methods, the subject matter of this thesis focuses on four instabilities, which impose local and global stability limits. All of these instabilities are relevant for the operation of a fusion reactor and a profound understanding of their behaviour is required in order to optimise the performance of such a reactor. Sawteeth, which are central relaxation oscillations common to most standard tokamak scenarios, have a significant effect on central plasma parameters. In TCV, systematic scans of the plasma shape have revealed a strong dependence of their behaviour on elongation κ and triangularity δ, with high κ, and low δ leading to shorter sawteeth with smaller crashes. This shape dependence is increased by applying central electron cyclotron heating. The response to additional heating power is determined by the role of ideal or resistive MHD in triggering the sawtooth crash. For plasma shapes where additional heating and consequently, a faster increase of the central pressure shortens the sawteeth, the low experimental limit of the pressure gradient within the q = 1 surface is consistent with ideal MHD predictions. The observed decrease

  4. La depresión en la infancia desde la perspectiva de las taxonomías empíricas

    OpenAIRE

    López Soler, Concepción; López Pina, José Antonio

    1998-01-01

    En este trabajo se analiza la depresión infantil desde el modelo de taxonomías empíricas propuesto por Achenbach y Edelbrock. Se revisan algunos aspectos diferenciales en el diagnóstico de la depresión en menores y adultos. La parte empírica se cent

  5. Parasites causing cerebral falciparum malaria bind multiple endothelial receptors and express EPCR and ICAM-1-binding PfEMP1

    DEFF Research Database (Denmark)

    Tuikue Ndam, Nicaise; Moussiliou, Azizath; Lavstsen, Thomas

    2017-01-01

    Background: Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates the binding and accumulation of infected erythrocytes (IE) to blood vessels and tissues. Specific interactions have been described between PfEMP1 and human endothelial proteins CD36, intercellular adhesion molecule-1...

  6. Modelling of diamagnetic stabilization of ideal MHD eigenmodes associated with the transport barrier

    International Nuclear Information System (INIS)

    Huysmans, G.; Sharapov, S.; Mikhailovskii, A.; Kerner, W.

    2001-01-01

    A new code, MISHKA-D (Drift MHD), has been developed as an extension of the ideal MHD code MISHKA-1 in order to investigate the finite gyroradius stabilizing effect of ion diamagnetic drift frequency, ω *i , on linear ideal MHD eigenmodes in tokamaks with shaped plasma cross-section. The MISHKA-D code gives a self-consistent computation of both stable and unstable eigenmodes with eigenvalues [γ] ≅ ω *i in plasmas with strong radial variation in the ion diamagnetic frequency. Test results of the MISHKA-D code show good agreement with the analytically obtained ω *i -spectrum and stability limits of the internal kink mode, n/m=1/1, used as a benchmark case. Finite-n ballooning and low-n kink (peeling) modes in the edge transport barrier just inside the separatrix are studied for H-mode plasma with the ω *i -effect included. The ion diamagnetic stabilization of the ballooning modes is found to be most effective for narrow edge pedestals. For low enough plasma density the ω *i - stabilization can lead to a second zone of ballooning stability, in which all the ballooning modes are stable for any value of the pressure gradient. For internal transport barriers typical of JET optimised shear discharges, the stabilizing influence of ion diamagnetic frequency on the n=1 global pressure driven disruptive mode is studied. A strong radial variation of ω *i is found to significantly decrease the stabilizing ω *i - effect on the n=1 mode, in comparison with the case of constant ω *i estimated at the foot of the internal transport barrier. (author)

  7. Conceptual design analysis of an MHD power conversion system for droplet-vapor core reactors. Final report

    International Nuclear Information System (INIS)

    Anghaie, S.; Saraph, G.

    1995-01-01

    A nuclear driven magnetohydrodynamic (MHD) generator system is proposed for the space nuclear applications of few hundreds of megawatts. The MHD generator is coupled to a vapor-droplet core reactor that delivers partially ionized fissioning plasma at temperatures in range of 3,000 to 4,000 K. A detailed MHD model is developed to analyze the basic electrodynamics phenomena and to perform the design analysis of the nuclear driven MHD generator. An incompressible quasi one dimensional model is also developed to perform parametric analyses

  8. Observation of bulk-ion heating in a tokamak plasma by application of positive and negative current pulses in TRIAM-1

    Energy Technology Data Exchange (ETDEWEB)

    Toi, K; Hiraki, N; Nakamura, K; Mitarai, O; Kawai, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1980-09-01

    A positive of negative current pulse induced by a pulsed toroidal electric field much higher than the Dreicer field increases the bulk-ion temperature of the plasma centre two to three times, without macroscopic plasma destruction. The decay time of the raised ion temperature agrees well with the prediction from neoclassical transport theory. The magnitude of the positive current pulse is limited by violent current disruption, and that of the negative current by a lack of MHD equilibrium which is due to a marked reduction of the total plasma current. The relevant current-driven instabilities in the turbulent heating of a tokamak plasma, skin heating and inward transfer of the energy deposition in the skin layer are briefly discussed.

  9. Regular shock refraction in planar ideal MHD

    International Nuclear Information System (INIS)

    Delmont, P; Keppens, R

    2010-01-01

    We study the classical problem of planar shock refraction at an oblique density discontinuity, separating two gases at rest, in planar ideal (magneto)hydrodynamics. In the hydrodynamical case, 3 signals arise and the interface becomes Richtmyer-Meshkov unstable due to vorticity deposition on the shocked contact. In the magnetohydrodynamical case, on the other hand, when the normal component of the magnetic field does not vanish, 5 signals will arise. The interface then typically remains stable, since the Rankine-Hugoniot jump conditions in ideal MHD do not allow for vorticity deposition on a contact discontinuity. We present an exact Riemann solver based solution strategy to describe the initial self similar refraction phase. Using grid-adaptive MHD simulations, we show that after reflection from the top wall, the interface remains stable.

  10. Effect of Induced Magnetic Field on MHD Mixed Convection Flow in Vertical Microchannel

    Science.gov (United States)

    Jha, B. K.; Aina, B.

    2017-08-01

    The present work presents a theoretical investigation of an MHD mixed convection flow in a vertical microchannel formed by two electrically non-conducting infinite vertical parallel plates. The influence of an induced magnetic field arising due to motion of an electrically conducting fluid is taken into consideration. The governing equations of the motion are a set of simultaneous ordinary differential equations and their exact solutions in dimensionless form have been obtained for the velocity field, the induced magnetic field and the temperature field. The expressions for the induced current density and skin friction have also been obtained. The effects of various non-dimensional parameters such as rarefaction, fluid wall interaction, the Hartmann number and the magnetic Prandtl number on the velocity, the induced magnetic field, the temperature, the induced current density, and skin friction have been presented in a graphical form. It is found that the effect of the Hartmann number and magnetic Prandtl number on the induced current density is found to have a decreasing nature at the central region of the microchannel.

  11. MHD Flows in Compact Astrophysical Objects Accretion, Winds and Jets

    CERN Document Server

    Beskin, Vasily S

    2010-01-01

    Accretion flows, winds and jets of compact astrophysical objects and stars are generally described within the framework of hydrodynamical and magnetohydrodynamical (MHD) flows. Analytical analysis of the problem provides profound physical insights, which are essential for interpreting and understanding the results of numerical simulations. Providing such a physical understanding of MHD Flows in Compact Astrophysical Objects is the main goal of this book, which is an updated translation of a successful Russian graduate textbook. The book provides the first detailed introduction into the method of the Grad-Shafranov equation, describing analytically the very broad class of hydrodynamical and MHD flows. It starts with the classical examples of hydrodynamical accretion onto relativistic and nonrelativistic objects. The force-free limit of the Grad-Shafranov equation allows us to analyze in detail the physics of the magnetospheres of radio pulsars and black holes, including the Blandford-Znajek process of energy e...

  12. Numerical study of the axisymmetric ideal MHD stability of Extrap

    International Nuclear Information System (INIS)

    Benda, M.

    1993-04-01

    A numerical study of the free-boundary axisymmetric (n=0) ideal magnetohydrodynamical (MHD) motions of the Extrap device is presented. The dependence of stability on current profiles in the plasma and currents in the external conductors is investigated. Results are shown for linear growth-rates and nonlinear saturation amplitudes and their dependence on plasma radius as well as on the conducting shell radius. A method combined of two different algorithms has been developed and tested. The interior region of the plasma is simulated by means of a Lagrangian Finite Element Method (FEM) for ideal magnetohydrodynamics, The method is based on a nonlinear radiation principle for the Lagrangian description of ideal MHD. The Boundary Element Method (BEM) is used together with the Lagrangian FEM to simulate nonlinear motion of an ideal MHD plasma behaviour in a vacuum region under the influence of external magnetic fields. 31 refs

  13. Variational formalism for kinetic-MHD instabilities in tokamaks

    International Nuclear Information System (INIS)

    Edery, D.; Garbet, X.; Roubin, J.P.; Samain, A.

    1991-07-01

    A variational formalism that includes in a consistent way the tokamak plasma fluid response to an electromagnetic field as well as the particle-field resonant interaction effects is presented. The integrability of the unperturbed motion of the particles is used to establish a general functional similar to the classical Lagrangian for the electromagnetic field, which is extremum with respect to the field potentials. This functional is the sum of fluid terms closely related to the classical MHD energy and of resonant terms describing the kinetic effects. The formalism is used to study a critical issue in tokamak confinement, namely the sawteeth stabilization by energetic particles

  14. Resistive MHD studies of TFTR discharges

    International Nuclear Information System (INIS)

    Hughes, M.H.; Phillips, M.W.; Sabbagh, S.A.; Budny, R.V.

    1991-01-01

    MHD instabilities, thought to be resistive in character, are frequently observed in the supershot operating regime of TFTR (var-epsilon β p ≤ 0.7). These instabilities are always accompanied by substantial degradation of the confinement. Similarly of interest are recent experiments at much larger β p (var-epsilon β p ≤ 1.6), achieved through ramping the current during the beam heating phase of the discharge. In this latter regime the confinement can exceed three times the corresponding L-mode value and the β value normalized to I/aB can be as large as 4.7. Representative discharges from each of these operating regimes have been analyzed using a linear resistive MHD stability code with equilibrium pressure and q profiles obtained initially from the TRANSP analysis code. The main difference between the two types of discharge, as far as stability is concerned is shown to be the shape of the current density profile. The sensitivity to the assumed parameters is discussed. 1 ref

  15. Waveguide and loop coupling to fast MHD toroidal eigenmodes

    International Nuclear Information System (INIS)

    Paoloni, F.J.

    1975-12-01

    Heating of plasmas by wave techniques requires an effective method of coupling rf energy to the plasma. In cavities the presence of weakly damped eigenmodes will enhance the loading of antennas when the wave frequency equals an eigenmode frequency. This report considers two methods of coupling to fast MHD eigenmodes in a toroidal cavity: one is by a waveguide mounted perpendicular to the vacuum vessel wall; and the other by a loop placed within the cavity

  16. Intermittency in MHD turbulence and coronal nanoflares modelling

    Directory of Open Access Journals (Sweden)

    P. Veltri

    2005-01-01

    Full Text Available High resolution numerical simulations, solar wind data analysis, and measurements at the edges of laboratory plasma devices have allowed for a huge progress in our understanding of MHD turbulence. The high resolution of solar wind measurements has allowed to characterize the intermittency observed at small scales. We are now able to set up a consistent and convincing view of the main properties of MHD turbulence, which in turn constitutes an extremely efficient tool in understanding the behaviour of turbulent plasmas, like those in solar corona, where in situ observations are not available. Using this knowledge a model to describe injection, due to foot-point motions, storage and dissipation of MHD turbulence in coronal loops, is built where we assume strong longitudinal magnetic field, low beta and high aspect ratio, which allows us to use the set of reduced MHD equations (RMHD. The model is based on a shell technique in the wave vector space orthogonal to the strong magnetic field, while the dependence on the longitudinal coordinate is preserved. Numerical simulations show that injected energy is efficiently stored in the loop where a significant level of magnetic and velocity fluctuations is obtained. Nonlinear interactions give rise to an energy cascade towards smaller scales where energy is dissipated in an intermittent fashion. Due to the strong longitudinal magnetic field, dissipative structures propagate along the loop, with the typical speed of the Alfvén waves. The statistical analysis on the intermittent dissipative events compares well with all observed properties of nanoflare emission statistics. Moreover the recent observations of non thermal velocity measurements during flare occurrence are well described by the numerical results of the simulation model. All these results naturally emerge from the model dynamical evolution without any need of an ad-hoc hypothesis.

  17. MHD stagnation point flow by a permeable stretching cylinder with Soret-Dufour effects

    Institute of Scientific and Technical Information of China (English)

    M Ramzan; M Farooq; T Hayat; A Alsaedi; J Cao

    2015-01-01

    Combined effects of Soret (thermal-diffusion) and Dufour (diffusion-thermo) in MHD stagnation point flow by a permeable stretching cylinder were studied. Analysis was examined in the presence of heat generation/absorption and chemical reaction. The laws of conservation of mass, momentum, energy and concentration are found to lead to the mathematical development of the problem. Suitable transformations were used to convert the nonlinear partial differential equations into the ordinary differential equations. The series solutions of boundary layer equations through momentum, energy and concentration equations were obtained. Convergence of the developed series solutions was discussed via plots and numerical values. The behaviors of different physical parameters on the velocity components, temperature and concentration were obtained. Numerical values of Nusselt number, skin friction and Sherwood number with different parameters were computed and analyzed. It is found that Dufour and Soret numbers result in the enhancement of temperature and concentration distributions, respectively.

  18. Accelerated Time-Domain Modeling of Electromagnetic Pulse Excitation of Finite-Length Dissipative Conductors over a Ground Plane via Function Fitting and Recursive Convolution

    Energy Technology Data Exchange (ETDEWEB)

    Campione, Salvatore [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Warne, Larry K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sainath, Kamalesh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Basilio, Lorena I. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-10-01

    In this report we overview the fundamental concepts for a pair of techniques which together greatly hasten computational predictions of electromagnetic pulse (EMP) excitation of finite-length dissipative conductors over a ground plane. In a time- domain, transmission line (TL) model implementation, predictions are computationally bottlenecked time-wise, either for late-time predictions (about 100ns-10000ns range) or predictions concerning EMP excitation of long TLs (order of kilometers or more ). This is because the method requires a temporal convolution to account for the losses in the ground. Addressing this to facilitate practical simulation of EMP excitation of TLs, we first apply a technique to extract an (approximate) complex exponential function basis-fit to the ground/Earth's impedance function, followed by incorporating this into a recursion-based convolution acceleration technique. Because the recursion-based method only requires the evaluation of the most recent voltage history data (versus the entire history in a "brute-force" convolution evaluation), we achieve necessary time speed- ups across a variety of TL/Earth geometry/material scenarios. Intentionally Left Blank

  19. Time-resolved observation of discrete and continuous MHD dynamo in the reversed-field pinch edge

    International Nuclear Information System (INIS)

    Ji, H.; Almagri, A.F.; Prager, S.C.; Sarff, J.S.

    1994-01-01

    We report the first experimental verification of the MHD dynamo in the RFP. A burst of magnetohydrodynamic (MHD) dynamo electric field is observed during the sawtooth crash, followed by an increase in the local parallel current in the MST RFP edge. By measuring each term, the parallel MHD mean-field Ohm's law is observed to hold within experimental error bars both between and during sawtooth crashes

  20. Non-linear Simulations of MHD Instabilities in Tokamaks Including Eddy Current Effects and Perspectives for the Extension to Halo Currents

    International Nuclear Information System (INIS)

    Hoelzl, M; Merkel, P; Lackner, K; Strumberger, E; Huijsmans, G T A; Aleynikova, K; Liu, F; Atanasiu, C; Nardon, E; Fil, A; McAdams, R; Chapman, I

    2014-01-01

    The dynamics of large scale plasma instabilities can be strongly influenced by the mutual interaction with currents flowing in conducting vessel structures. Especially eddy currents caused by time-varying magnetic perturbations and halo currents flowing directly from the plasma into the walls are important. The relevance of a resistive wall model is directly evident for Resistive Wall Modes (RWMs) or Vertical Displacement Events (VDEs). However, also the linear and non-linear properties of most other large-scale instabilities may be influenced significantly by the interaction with currents in conducting structures near the plasma. The understanding of halo currents arising during disruptions and VDEs, which are a serious concern for ITER as they may lead to strong asymmetric forces on vessel structures, could also benefit strongly from these non-linear modeling capabilities. Modeling the plasma dynamics and its interaction with wall currents requires solving the magneto-hydrodynamic (MHD) equations in realistic toroidal X-point geometry consistently coupled with a model for the vacuum region and the resistive conducting structures. With this in mind, the non-linear finite element MHD code JOREK [1, 2] has been coupled [3] with the resistive wall code STARWALL [4], which allows us to include the effects of eddy currents in 3D conducting structures in non-linear MHD simulations. This article summarizes the capabilities of the coupled JOREK-STARWALL system and presents benchmark results as well as first applications to non-linear simulations of RWMs, VDEs, disruptions triggered by massive gas injection, and Quiescent H-Mode. As an outlook, the perspectives for extending the model to halo currents are described