Magnetohydrodynamic (MHD) power plant interface engineering
L. E. Van Bibber; D. A. Wiseman; J. W. Cuchens
1990-01-01
This report summarizes the results of EPRI Research Project 2466-10. The objective of this project was to identify the preliminary interface requirements and characteristics for a coal-fired magnetohydrodynamic retrofit power plant located at the Scholz Generating Station, Sneads, Florida. An initial building arrangement has been developed and incorporated into the plot plan of the Scholz Generating Station. An MHD process
ERIC Educational Resources Information Center
Kantrowitz, Arthur; Rosa, Richard J.
1975-01-01
Explains the operation of the Magnetohydrodynamic (MHD) generator and advantages of the system over coal, oil or nuclear powered generators. Details the development of MHD generators in the United States and Soviet Union. (CP)
Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Barnes, P.R. [Oak Ridge National Lab., TN (United States); Meliopoulos, A.P.S. [Georgia Inst. of Tech., Atlanta, GA (United States). Dept. of Electrical Engineering
1992-02-01
This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T&D) systems. 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. It can result in the flow of a quasi-dc current in grounded power lines and in the subsequent magnetic saturation of transformers. This saturation, in turn, causes 6-Hz harmonic distortion and an increase in the reactive power required by generation facilities. This report analyzes and discusses these phenomena. The MHD-EMP environment is briefly discussed, and a simplified form of the earth-induced electric field is developed for use in a parametric study of transmission line responses. Various field coupling models are described, and calculated results for the responses of both transmission- and distribution-class power lines are presented. These calculated responses are compared with measurements of transformer operation under dc excitation to infer the MHD-EMP response of these power system components. It is found that the MHD-EMP environment would have a marked effect on a power system by inducing up to several hundreds of amperes of quasi-dc current on power lines. These currents will cause transformers to saturate which could result in excessive harmonic generation, voltage swings, and voltage suppression. The design of critical facilities which are required to operate during and after MHD-EMP events will have to be modified in order to mitigate the effects of these abnormal power system conditions.
Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Barnes, P.R. (Oak Ridge National Lab., TN (United States)); Meliopoulos, A.P.S. (Georgia Inst. of Tech., Atlanta, GA (United States). Dept. of Electrical Engineering)
1992-02-01
This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T D) systems. 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. It can result in the flow of a quasi-dc current in grounded power lines and in the subsequent magnetic saturation of transformers. This saturation, in turn, causes 6-Hz harmonic distortion and an increase in the reactive power required by generation facilities. This report analyzes and discusses these phenomena. The MHD-EMP environment is briefly discussed, and a simplified form of the earth-induced electric field is developed for use in a parametric study of transmission line responses. Various field coupling models are described, and calculated results for the responses of both transmission- and distribution-class power lines are presented. These calculated responses are compared with measurements of transformer operation under dc excitation to infer the MHD-EMP response of these power system components. It is found that the MHD-EMP environment would have a marked effect on a power system by inducing up to several hundreds of amperes of quasi-dc current on power lines. These currents will cause transformers to saturate which could result in excessive harmonic generation, voltage swings, and voltage suppression. The design of critical facilities which are required to operate during and after MHD-EMP events will have to be modified in order to mitigate the effects of these abnormal power system conditions.
NASA Astrophysics Data System (ADS)
1981-09-01
The estimated plant capital cost for a coal fired 200 MWE electric generating plant with open cycle magnetohydrodynamics is divided into principal accounts based on Federal Energy Regulatory Commision account structure. Each principal account is defined and its estimated cost subdivided into identifiable and major equipment systems. The cost data sources for compiling the estimates, cost parameters, allotments, assumptions, and contingencies, are discussed. Uncertainties associated with developing the costs are quantified to show the confidence level acquired. Guidelines established in preparing the estimated costs are included. Based on an overall milestone schedule related to conventional power plant scheduling experience and starting procurement of MHD components during the preliminary design phase there is a 6 1/2-year construction period. The duration of the project from start to commercial operation is 79 months. The engineering phase of the project is 4 1/2 years; the construction duration following the start of the man power block is 37 months.
DESIGN & EXPERIMENTATION OF HIGH CURRENT DENSITY DC MAGNETOHYDRODYNAMIC (MHD) MICROPUMP
Kassegne, Samuel Kinde
DESIGN & EXPERIMENTATION OF HIGH CURRENT DENSITY DC MAGNETOHYDRODYNAMIC (MHD) MICROPUMP Nguyen: Design, Fabrication, & Experimentation of DC MHD Micropump OF THE THESIS Design, Fabrication, & Experimentation of DC MHD Micropump by Bao Thanh Nguyen Master of Science
Diagnostic development and support of MHD (magnetohydrodynamics) test facilities
Not Available
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.
Barnes, P.R.; Tesche, F.M.; McConnell, B.W.; Vance, E.F.
1993-09-01
A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth's magnetic field and produces a strong magnetohydrodynamic-electromagnetic pulse (MHD-EMP). MHD-EMP is similar to solar geomagnetic storms in its global and low frequency (less than 1 Hz) nature except that it can be more intense with a shorter duration. It will induce quasi-dc currents in long lines. The MHD-EMP induced currents may cause large voltage fluctuations and severe harmonic distortion in commercial electric power systems. Several MHD-EMP coupling models for predicting the induced current on a wide variety of conducting structures are described, various simulation concepts are summarized, and the results from several MHD-EMP tests are presented. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building, and the commercial power harmonics and voltage swings must be addressed. It is found that facilities can be protected against MHD-EMP by using methods which are consistent with standard engineering practices. MHD-EMP Interaction Analysis, Power Line Model, MHD-EMP Protection Guidelines, Transformer Test.
Theoretical and experimental study of MHD (magnetohydrodynamic) micropump
Jaesung Jang; Seung S. Lee
2000-01-01
This paper presents a novel micropump of which pumping mechanism is based upon magnetohydrodynamic (MHD) principles. MHD is the study of flow of electrically conducting liquids in electric and magnetic fields. Lorentz force is the pumping source of conductive, aqueous solutions in the MHD micropump. Conducting fluid in the microchannel of the MHD micropump is driven by Lorentz force in
Magnetohydrodynamic (MHD) driven droplet mixer
Lee, Abraham P.; Lemoff, Asuncion V.; Miles, Robin R.
2004-05-11
A magnetohydrodynamic fluidic system mixes a first substance and a second substance. A first substrate section includes a first flow channel and a first plurality of pairs of spaced electrodes operatively connected to the first flow channel. A second substrate section includes a second flow channel and a second plurality of pairs of spaced electrodes operatively connected to the second flow channel. A third substrate section includes a third flow channel and a third plurality of pairs of spaced electrodes operatively connected to the third flow channel. A magnetic section and a control section are operatively connected to the spaced electrodes. The first substrate section, the second substrate section, the third substrate section, the first plurality of pairs of spaced electrodes, the second plurality of pairs of spaced electrodes, the third plurality of pairs of spaced electrodes, the magnetic section, and the control section are operated to move the first substance through the first flow channel, the second substance through the second flow channel, and both the first substance and the second substance into the third flow channel where they are mixed.
Not Available
1988-03-15
This progress report of the Space Power MHD System project presents the accomplishments during 1 November 1987 through 31 January 1988. The scope of work covered encompasses the definition of an MHD power system conceptual design and development plan (Task 1). Progress included the following: Subcontracts were issued to the MIT Plasma Fusion Center and the Westinghouse R and D Center. The performance of the 100 MW 500 sec. power system was optimized and the design concept finalized, including mass and energy balances. Mass and cost estimates were prepared. A design review was held at DOE/PETC. This also included the review of the technical issues definition and of the R and D Plan. Following the review, a final iteration on the conceptual design was initiated. Formulation of the R and D Plan was continued. Preparation of the Task 1 R and D Report was initiated. 12 figs.
NASA Technical Reports Server (NTRS)
1981-01-01
Main elements of the design are identified and explained, and the rationale behind them was reviewed. Major systems and plant facilities are listed and discussed. Construction cost and schedule estimates are presented, and the engineering issues that should be reexamined are identified. The latest (1980-1981) information from the MHD technology program is integrated with the elements of a conventional steam power electric generating plant.
Explosively-driven magnetohydrodynamic (MHD) generator studies
Agee, F.J.; Lehr, F.M. [Phillips Lab., Kirtland AFB, NM (United States); Vigil, M.; Kaye, R. [Sandia National Labs., Albuquerque, NM (United States); Gaudet, J.; Shiffler, D. [New Mexico Univ., Albuquerque, NM (United States)
1995-08-01
Plasma jet generators have been designed and tested which used an explosive driver and shocktube with a rectangular cross section that optimize the flow velocity and electrical conductivity. The latest in a series of designs has been tested using a reactive load to diagnose the electrical properties of the MHD generator/electromagnet combination. The results of these tests indicate that the plasma jet/MHD generator design does generate a flow velocity greater than 25 km/s and produces several gigawatts of pulsed power in a very small package size. A larger, new generator design is also presented.
Mesofluidic magnetohydrodynamic power generation
Fucetola, Jay J
2012-01-01
Much of the previous research into magnetohydrodynamics has involved large-scale systems. This thesis explores the miniaturization and use of devices to convert the power dissipated within an expanding gas flow into ...
Hals, F.A.
1981-09-01
This report is the final document reporting information developed in Task III of a Program Study of Potential Early Commercial MHD Power Plants under NASA Contract DEN 3-51. Task II consisted of the conceptual design of one of the reference plants analyzed in Task I. The Task II plant was identified as attractive and selected on the basis of Task I results. It employs oxygen enrichment of the combustion air and has a nominal plant capacity of 950 MW/sub e/. Task II permitted more detailed design analysis than that possible in the initial parametric analysis. Task III reported on in this document consisted of parametric performance and cost analyses of two plants of the same basic configuration as the plant studied in Task II but smaller in size. The two power plant sizes investigated in Task III correspond to nominal plant capacities of 200 MW/sub e/ and 500 MW/sub e/, respectively. The smallest plant size of 200 MW/sub e/ corresponds to the size presently specified for the Engineering Test Facility (ETF). In addition to providing cost estimates for each of the two downsized plants in Task III consistent with the cost analyses used in Task II, a capital cost estimate for a ''first of its kind'' power plant was developed for the smallest plant size of 200 MW/sub e/. This latter estimate served to identify the impact of applying learning curve factors to cost estimates of new technology items. Also, a detailed breakdown of the operating and maintenance cost of the larger Task II plant was a separate work subtask item of Task III. 8 refs., 52 figs., 36 tabs.
Disk magnetohydrodynamic power conversion system for NERVA reactor
William D. Jackson; Frances E. Bernard; Robert R. Holman; Craig D. Maxwell; George R. Seikel
1993-01-01
The combination of a magnetohydrodynamic (MHD) generator of the disk type with a NERVA reactor yields an advanced power system particularly suited to space applications with the capability of producing up to gigawatt pulses and multi-megawatt continuous operation. Several unique features result from the combination of this type of reactor and a disk MHD generator in which hydrogen serves as
A high current density DC magnetohydrodynamic (MHD) micropump
Alexandra Homsy; Sander Koster; Jan C. T. Eijkel; Berg van den Albert; F. Lucklum; E. Ver-poorte; Rooij de Nico F
2005-01-01
This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-ľm-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachined frit-like structure that connects the pumping channel to side reservoirs, where platinum electrodes are located. Current
NASA Technical Reports Server (NTRS)
1981-01-01
The results of magnet system special investigations listed below are summarized: 4 Tesla Magnet Alternate Design Study; 6 Tesla Magnet Manufacturability Study. The conceptual design for a 4 Tesla superconducting magnet system for use with an alternate (supersonic) ETF power train is described, and estimated schedule and cost are identified. The magnet design is scaled from the ETF 6 T Tesla design. Results of a manufacturability study and a revised schedule and cost estimate for the ETF 6 T magnet are reported. Both investigations are extensions of the conceptual design of a 6 T magnet system performed earlier as a part of the overall MED-ETF conceptual design described in Conceptual Design Engineering Report (CDER) Vol. V, System Design Description (SDD) 503 dated September, 1981, DOE/NASA/0224-1; NASA CR-165/52.
NASA Technical Reports Server (NTRS)
Hoover, D. Q.
1976-01-01
Electric power plant costs and efficiencies are presented for three basic open-cycle MHD systems: (1) direct coal fired system, (2) a system with a separately fired air heater, and (3) a system burning low-Btu gas from an integrated gasifier. Power plant designs were developed corresponding to the basic cases with variation of major parameters for which major system components were sized and costed. Flow diagrams describing each design are presented. A discussion of the limitations of each design is made within the framework of the assumptions made.
K. D. Parks; A. C. Sheth
1988-01-01
Magnetohydrodynamics is a branch of the physical sciences dealing with the electromagnetic fields and electrically conduction gases and liquids. Examples of MHD are everywhere, from stars and nuclear fusion to applications like MHD electrical power generation, i.e. when electrical conductors cut magnetic field lines, an electromotive force (EMF) is induced. If electrodes and external circuits are connected, current will flow.
Pulse Detonation Rocket Magnetohydrodynamic Power Experiment
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Jones, J. E.; Dobson, C. C.; Cole, J. W.; Thompson, B. R.; Plemmons, D. H.; Turner, M. W.
2003-01-01
The production of onboard electrical power by pulse detonation engines is problematic in that they generate no shaft power; however, pulse detonation driven magnetohydrodynamic (MHD) power generation represents one intriguing possibility for attaining self-sustained engine operation and generating large quantities of burst power for onboard electrical systems. To examine this possibility further, a simple heat-sink apparatus was developed for experimentally investigating pulse detonation driven MHD generator concepts. The hydrogen oxygen fired driver was a 90 cm long stainless steel tube having a 4.5 cm square internal cross section and a short Schelkin spiral near the head end to promote rapid formation of a detonation wave. The tube was intermittently filled to atmospheric pressure and seeded with a CsOH/methanol prior to ignition by electrical spark. The driver exhausted through an aluminum nozzle having an area contraction ratio of A*/A(sub zeta) = 1/10 and an area expansion ratio of A(sub zeta)/A* = 3.2 (as limited by available magnet bore size). The nozzle exhausted through a 24-electrode segmented Faraday channel (30.5 cm active length), which was inserted into a 0.6 T permanent magnet assembly. Initial experiments verified proper drive operation with and without the nozzle attachment, and head end pressure and time resolved thrust measurements were acquired. The exhaust jet from the nozzle was interrogated using a polychromatic microwave interferometer yielding an electron number density on the order of 10(exp 12)/cm at the generator entrance. In this case, MHD power generation experiments suffered from severe near-electrode voltage drops and low MHD interaction; i.e., low flow velocity, due to an inherent physical constraint on expansion with the available magnet. Increased scaling, improved seeding techniques, higher magnetic fields, and higher expansion ratios are expected to greatly improve performance.
Rackliffe, G.B.; Crouse, J.C.; Legro, J.R.; Kruse, V.J.
1987-01-01
This paper quantifies the quasi-dc currents induced on a power system by a simulated magnetohydrodynamic pulse (MHD-EMP). The determination of the quasi-dc currents is based upon the similarity between the effects of MHD-EMP and the impact of geomagnetic storms. The paper highlights how the methodology to calculate geomagnetic-induced currents from solar storms was modified to calculate the currents induced by a MHD-EMP event. After specification of the MHD-EMP environment and the selection of a power system to study, the quasi-dc currents induced in the power system were calculated.
Laser-powered MHD generators for space application
Jalufka, N.W.
1986-10-01
Magnetohydrodynamic (MHD) energy conversion systems of the pulsed laser-supported detonation (LSD) wave, plasma MHD, and liquid-metal MHD (LMMHD) types are assessed for their potential as space-based laser-to-electrical power converters. These systems offer several advantages as energy converters relative to the present chemical, nuclear, and solar devices, including high conversion efficiency, simple design, high-temperature operation, high power density, and high reliability. Of these systems, the Brayton cycle liquid-metal MHD system appears to be the most attractive. The LMMHD technology base is well established for terrestrial applications, particularly with regard to the generator, mixer, and other system components. However, further research is required to extend this technology base to space applications and to establish the technology required to couple the laser energy into the system most efficiently. Continued research on each of the three system types is recommended.
The optimization air separation plants for combined cycle MHD-power plant applications
A. J. Juhasz; H. Springmann; R. Greenberg
1980-01-01
Some of the design approaches being employed during a current supported study directed at developing an improved air separation process for the production of oxygen enriched air for magnetohydrodynamics (MHD) combustion are outlined. The ultimate objective is to arrive at conceptual designs of air separation plants, optimized for minimum specific power consumption and capital investment costs, for integration with MHD
Anisotropic Scaling of Magnetohydrodynamic Turbulence Timothy S. Horbury*
Oughton, Sean
Anisotropic Scaling of Magnetohydrodynamic Turbulence Timothy S. Horbury* The Blackett Laboratory of the anisotropic power and scaling of magnetic field fluctuations in inertial range magnetohydrodynamic turbulence on one of these, the anisotropy of the energy spectrum of magnetohydrodynamic (MHD) turbulence
Disk magnetohydrodynamic power conversion system for NERVA reactor
NASA Astrophysics Data System (ADS)
Jackson, William D.; Bernard, Frances E.; Holman, Robert R.; Maxwell, Craig D.; Seikel, George R.
1993-01-01
The combination of a magnetohydrodynamic (MHD) generator of the disk type with a NERVA reactor yields an advanced power system particularly suited to space applications with the capability of producing up to gigawatt pulses and multi-megawatt continuous operation. Several unique features result from the combination of this type of reactor and a disk MHD generator in which hydrogen serves as the plasma working fluid. Cesium seedings is utilized under conditions which enable the generator to operate stably in the non-equilibrium electrical conduction mode. In common with all practical MHD generators, the disk output is DC and voltages in the range 20-100 kV are attainable. This leads to a simplification of the power conditioning system and a major reduction in specific mass. Taken together with the high performance capabilities of the NERVA reactor, the result is an attractively low overall system specific mass. Further, the use of non-equilibrium ionization enables system specific enthalpy extractions in excess of 40% to be attained. This paper reports the results of a study to establish the basis for the design of a cesium seeded hydrogen MHD disk generator. Generator performance results are presented in terms of a stability factor which is related to cesium seeded hydrogen plasma behavior. It is shown that application of the results already obtained with cesium seeded noble gases (argon and helium) to the case of hydrogen as the working fluid in a disk MHD generator enables a high performance power system to be defined.
Disk magnetohydrodynamic power conversion system for NERVA reactor
Jackson, W.D. (HMJ Corporation. 10400 Connecticut Ave., Kensington, Maryland 20895 (United States)); Bernard, F.E. (Westinghouse Corp., P.O. Box 355, Pittsburgh, Pennsylvania 15230 (United States)); Holman, R.R. (HMJ Corporation, 10400 Connecticut Ave., Kensington, Maryland 20895 (United States)); Maxwell, C.D. (STD Research Corp., P.O. Box C, Arcadia, California 91006 (United States)); Seikel, G.R. (SeiTec, Inc., P.O. Box 81264, Cleveland, Ohio 44181 (United States))
1993-01-15
The combination of a magnetohydrodynamic (MHD) generator of the disk type with a NERVA reactor yields an advanced power system particularly suited to space applications with the capability of producing up to gigawatt pulses and multi-megawatt continuous operation. Several unique features result from the combination of this type of reactor and a disk MHD generator in which hydrogen serves as the plasma working fluid. Cesium seedings is utilized under conditions which enable the generator to operate stably in the non-equilibrium electrical conduction mode. In common with all practical MHD generators, the disk output is DC and voltages in the range 20--100 kV are attainable. This leads to a simplification of the power conditioning system and a major reduction in specific mass. Taken together with the high performance capabilities of the NERVA reactor, the result is an attractively low overall system specific mass. Further, the use of non-equilibrium ionization enables system specific enthalpy extractions in excess of 40% to be attained. This paper reports the results of a study to establish the basis for the design of a cesium seeded hydrogen MHD disk generator. Generator performance results are presented in terms of a stability factor which is related to cesium seeded hydrogen plasma behavior. It is shown that application of the results already obtained with cesium seeded noble gases (argon and helium) to the case of hydrogen as the working fluid in a disk MHD generator enables a high performance power system to be defined.
Not Available
1987-06-01
This report presents a study of the nuclear weapons magnetohydrodynamic (MHD) effects on submarine communications cables. The study consisted of the analysis and interpretation of currently available data on submarine cable systems TAT-4, TAT-6, and TAT-7. The primary result of the study is that decrease of the effective resistivity with frequency over the available experimental range, coupled with the model results, leads to quite small effective resistivities at the MHD characteristic frequencies, and hence small earth potential differences. Thus, it appears that submarine cable systems are less susceptible to an MHD threat than their land-based counter-parts.
Experimental program for investigation of high power density MHD
NASA Astrophysics Data System (ADS)
Lineberry, J. T.; Schmidt, H. J.; Chapman, J. N.
Research on magnetohydrodynamic (MHD) power generation, directed at the proof-of-concept of combustion MHD as a viable source for use with space-based weapons systems, is described. Currently, small-scale laboratory evaluations of a solid-aluminum, carbon-fueled hybrid combustor are being completed. Ultimate plans for this research include coupling of this combustor to an MHD generator to demonstrate high power density in the laboratory. This report includes experimental results from the initial hybrid combustor tests. The design of this combustor system and its design point are detailed. Experimental data from firings are presented and analyzed. The burn or regression rate for this fuel is summarized. The combustor tests have been successful; the design point for this system was readily achieved and sustained.
Ionospheric power consumption in global MHD Simulation predicted from solar wind measurements
Minna Palmroth; Hannu E. J. Koskinen; Tuija I. Pulkkinen; Pekka Janhunen
2004-01-01
Ionospheric power consumption in a global magnetohydrodynamic (MHD) simulation is investigated. The sum of Joule heating and precipitation power integrated over both hemispheres is calculated in four simulation runs. The simulation results of the total ionospheric dissipation are correlated with solar wind density, velocity, and magnetic field using a linear multi-variable fit and a power law. The fitting procedure yields
MHD power conversion system for NERVA reactor
Seikel, G.R.; Condit, W.C.
1985-01-01
Optimized linear magnetohydrodynamic (MHD) systems to produce 200 MWe for 1000 seconds are defined. For the specific mission envisioned, a mass flow of 45.36 Kg/sec (100 lbs/sec) of hydrogen is available to the system. Westinghouse NERVA reactor technology can heat this mass flow of hydrogen to 2550 K at a pressure of 12 atm. This hydrogen flow is assumed to be seeded with cesium to obtain the required MHD generator conductivity. For each MHD system concept considered, the MHD generator design was optimized in terms of operating Mach number, load parameter, and cesium seed fraction. The simplest concept, an open-cycle MHD system, is optimized by minimizing the total magnet plus cesium seed mass. The resulting magnet and magnet plus seed mass are 44092 and 54143 Kg respectively. The second concept considered was an open-cycle MHD system with seed recovery and reuse. It is optimized by minimizing the magnet mass. The resulting magnet mass is 40110 Kg. A third concept, a closed-cycle MHD system, was also considered. If only equilibrium conductivity is considered, cesium seeded hydrogen is shown to be the more attractive than cesium seeded helium, and the optimum generator would be identical to that for the open-cycle MHD system with seed recovery.
Power Requirement for Nonequilibrium MHD-Bypass Scramjet
NASA Technical Reports Server (NTRS)
Park, Chul; Bogdanoff, David W.; Mehta, Unmeel
2000-01-01
It has been suggested previously that the performance of scramjet propulsion system may be improved by the use of magnetohydrodynamic (MHD) energy bypass: an MHD generator could be made to decelerate the flow entering the combustor, thereby improving combustion efficiency, and the electrical power generated could be made to accelerate the flow exiting from the combustor prior to expanding through the nozzle. In one of such proposed schemes, the MHD generator is proposed to be operated at a low temperature and ionization is to be achieved under nonequilibrium by the application of an external power. In the present work, the required power of such an external source is calculated assuming a 100%-efficient nonequilibrium ionization scheme. The power required is that needed to prevent the degree of ionization from reaching equilibrium with the low gas temperature. The flow is seeded with potassium or cesium. Specific impulse is calculated with and without turbulent friction. The results show that, for typical intended flight conditions, the specific impulse obtained is substantially higher than that of a typical scramjet, but the required external-power is several times that of the power generated in the MHD generator.
Pulse Detonation Rocket MHD Power Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Cook, Stephen (Technical Monitor)
2002-01-01
A pulse detonation research engine (MSFC (Marshall Space Flight Center) Model PDRE (Pulse Detonation Rocket Engine) G-2) has been developed for the purpose of examining integrated propulsion and magnetohydrodynamic power generation applications. The engine is based on a rectangular cross-section tube coupled to a converging-diverging nozzle, which is in turn attached to a segmented Faraday channel. As part of the shakedown testing activity, the pressure wave was interrogated along the length of the engine while running on hydrogen/oxygen propellants. Rapid transition to detonation wave propagation was insured through the use of a short Schelkin spiral near the head of the engine. The measured detonation wave velocities were in excess of 2500 m/s in agreement with the theoretical C-J velocity. The engine was first tested in a straight tube configuration without a nozzle, and the time resolved thrust was measured simultaneously with the head-end pressure. Similar measurements were made with the converging-diverging nozzle attached. The time correlation of the thrust and head-end pressure data was found to be excellent. The major purpose of the converging-diverging nozzle was to configure the engine for driving an MHD generator for the direct production of electrical power. Additional tests were therefore necessary in which seed (cesium-hydroxide dissolved in methanol) was directly injected into the engine as a spray. The exhaust plume was then interrogated with a microwave interferometer in an attempt to characterize the plasma conditions, and emission spectroscopy measurements were also acquired. Data reduction efforts indicate that the plasma exhaust is very highly ionized, although there is some uncertainty at this time as to the relative abundance of negative OH ions. The emission spectroscopy data provided some indication of the species in the exhaust as well as a measurement of temperature. A 24-electrode-pair segmented Faraday channel and 0.6 Tesla permanent magnet assembly were then installed on Marshall Space Flight Center's (MSFC's) rectangular channel pulse detonation research engine. Magnetohydrodynamic (MHD) electrical power extraction experiments were carried out for a range of load impedances in which cesium hydroxide seed (dissolved in methanol) was sprayed into the gaseous oxygen/hydrogen propellants. Positive power extraction was obtained, but preliminary analysis of the data indicated that the plasma electrical conductivity is lower than anticipated and the near-electrode voltage drop is not negligible. It is believed that the electrical conductivity is reduced due to a large population of negative OH ions. This occurs because OH has a strong affinity for capturing free electrons. The effect of near-electrode voltage drop is associated with the high surface-to-volume ratio of the channel (1-inch by 1-inch cross-section) where surface effects play a dominant role. As usual for MHD devices, higher performance will require larger scale devices. Overall, the gathered data is extremely valuable from the standpoint of understanding plasma behavior and for developing empirical scaling laws.
NASA Technical Reports Server (NTRS)
Benyo, Theresa L.
2010-01-01
This paper describes the preliminary results of a thermodynamic cycle analysis of a supersonic turbojet engine with a magnetohydrodynamic (MHD) energy bypass system that explores a wide range of MHD enthalpy extraction parameters. Through the analysis described here, it is shown that applying a magnetic field to a flow path in the Mach 2.0 to 3.5 range can increase the specific thrust of the turbojet engine up to as much as 420 N/(kg/s) provided that the magnitude of the magnetic field is in the range of 1 to 5 Tesla. The MHD energy bypass can also increase the operating Mach number range for a supersonic turbojet engine into the hypersonic flight regime. In this case, the Mach number range is shown to be extended to Mach 7.0.
MHD-EMP interaction with power transmission and distribution systems
Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Barnes, P.R. [Oak Ridge National Lab., TN (United States)
1991-12-01
A nuclear detonation at altitudes of several hundred kilometers above the earth will distort the earth`s magnetic field and results in a time-variation of the geomagnetic field on the earth`s surface. This magnetic field interacts with the finitely conducting earth to produce a time varying electric field, also on the earth`s surface. Known at the magnetohydrodynamic electromagnetic pulse (MHD-EMP), this resulting E-field can induce a net voltage in long electrical conductors, such as power transmission lines. If these conductors are electrically connected to the earth at both ends, a current can be induced to flow in the conductors, and this can cause damage or upset to certain electrical systems. This paper presents the results of a study on the interaction of the MHD-EMP with power transmission and distribution (T&D) systems. A brief overview of the MHD-EMP environment used in the study is presented, and the analytical models used for estimating the coupling of this environment to T&D lines are discussed. Because of the quasi-static nature of MHD-EMP, the models are essentially simple DC circuit models. However, complications arise in attempting to treat realistic line configurations having a large number of support towers and an overhead shield or neutral wires. There models are discussed in detail. 3 refs., 5 figs., 1 tab.
MHD-EMP interaction with power transmission and distribution systems
Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Barnes, P.R. (Oak Ridge National Lab., TN (United States))
1991-01-01
A nuclear detonation at altitudes of several hundred kilometers above the earth will distort the earth's magnetic field and results in a time-variation of the geomagnetic field on the earth's surface. This magnetic field interacts with the finitely conducting earth to produce a time varying electric field, also on the earth's surface. Known at the magnetohydrodynamic electromagnetic pulse (MHD-EMP), this resulting E-field can induce a net voltage in long electrical conductors, such as power transmission lines. If these conductors are electrically connected to the earth at both ends, a current can be induced to flow in the conductors, and this can cause damage or upset to certain electrical systems. This paper presents the results of a study on the interaction of the MHD-EMP with power transmission and distribution (T D) systems. A brief overview of the MHD-EMP environment used in the study is presented, and the analytical models used for estimating the coupling of this environment to T D lines are discussed. Because of the quasi-static nature of MHD-EMP, the models are essentially simple DC circuit models. However, complications arise in attempting to treat realistic line configurations having a large number of support towers and an overhead shield or neutral wires. There models are discussed in detail. 3 refs., 5 figs., 1 tab.
NASA Astrophysics Data System (ADS)
Walker, A. D. M.
2014-12-01
Magnetohydrodynamic (MHD) waves in the solar wind and magnetosphere are propagated in a medium whose velocity is comparable to or greater than the wave velocity and which varies in both space and time. In the approximation where the scales of the time and space variation are long compared with the period and wavelength, the ray-tracing equations can be generalized and then include an additional first-order differential equation that determines the variation of frequency. In such circumstances the wave can exchange energy with the background: wave energy is not conserved. In such processes the wave action theorem shows that the wave action, defined as the ratio of the wave energy to the frequency in the local rest frame, is conserved. In this paper we discuss ray-tracing techniques and the energy exchange relation for MHD waves. We then provide a unified account of how to deal with energy transport by MHD waves in non-uniform media. The wave action theorem is derived directly from the basic MHD equations for sound waves, transverse Alfvén waves, and the fast and slow magnetosonic waves. The techniques described are applied to a number of illustrative cases. These include a sound wave in a medium undergoing a uniform compression, an isotropic Alfvén wave in a steady-state shear layer, and a transverse Alfvén wave in a simple model of the magnetotail undergoing compression. In each case the nature and magnitude of the energy exchange between wave and background is found.
Simulation of high-frequency solar wind power spectra using Hall magnetohydrodynamics
S. Ghosh; E. Siregar; D. A. Roberts; M. L. Goldstein
1996-01-01
Solar wind frequency spectra show a distinct steepening of the f-5\\/3 power law inertial range spectrum at frequencies above the Doppler-shifted ion cyclotron frequency. This is commonly attributed to dissipation due to wave-particle interactions. We consider the extent to which this steepening can be described, using a magnetohydrodynamic formulation that includes the Hall term. An important characteristic of Hall MHD
A. G. Wehr; R. Tang
1981-01-01
The MHD Energy Center has constructed a test stand that will simulate the conditions that are present at any point in a coal-fired magnetohydrodynamic (MHD) power plant. This test stand was used to examine the effect of primary combustion stoichiometry and various secondary combustion parameters on the generation of nitrogen oxides. The secondary combustion air was injected at eight different
Off-design study of an open-cycle MHD power plant with oxygen enrichment
Geyer, H.K.; Berry, G.F.
1981-01-01
This paper explores some of the more important aspects of off-design operation for an magnetohydrodynamic (MHD) power plant. An essential requirement is that the plant be designed to meet part-load and overload conditions. Furthermore, the optimal design should be subject to a specified load demand curve. For off-design regimes, an analysis is made to determine the compatible joint operating conditions for an MHD topping cycle, a steam bottoming plant, a turbine train, a compressor, and an oxygen separation plant. The analysis performed is subject to constraints (e.g. metal temperatures, second law violations, component performance requirements, environmental considerations). 12 refs.
Chatterjee, Dipankar; Amiroudine, Sakir
2011-02-01
A comprehensive non-isothermal Lattice Boltzmann (LB) algorithm is proposed in this article to simulate the thermofluidic transport phenomena encountered in a direct-current (DC) magnetohydrodynamic (MHD) micropump. Inside the pump, an electrically conducting fluid is transported through the microchannel by the action of an electromagnetic Lorentz force evolved out as a consequence of the interaction between applied electric and magnetic fields. The fluid flow and thermal characteristics of the MHD micropump depend on several factors such as the channel geometry, electromagnetic field strength and electrical property of the conducting fluid. An involved analysis is carried out following the LB technique to understand the significant influences of the aforementioned controlling parameters on the overall transport phenomena. In the LB framework, the hydrodynamics is simulated by a distribution function, which obeys a single scalar kinetic equation associated with an externally imposed electromagnetic force field. The thermal history is monitored by a separate temperature distribution function through another scalar kinetic equation incorporating the Joule heating effect. Agreement with analytical, experimental and other available numerical results is found to be quantitative. PMID:21053082
Two-dimensional non-reacting jet-gas mixing in an MHD (magnetohydrodynamic) second stage combustor
S. L. Chang; S. A. Lottes; G. F. Berry
1990-01-01
Computer simulation is used to aid in the design of a magnetohydrodynamic (MHD) second stage combustor. A two-dimensional steady state computer model, based on mass and momentum conservation laws for multiple gas species, is used to simulate the hydrodynamics of the combustor in which a jet of oxidizer is injected into a confined cross-stream gas flow. The model predicts jet-gas
Jones, A.R.
1985-08-01
This System Design Description and Specification provides the basis for the design of the magnetohydrodynamic (MHD) Power Train (PT) for a nominal 200 MWe early commercial tiHD/Steam Power Plant. This document has been developed under Task 2, Conceptual Design, of Contract DE-AC22-83PC60575 and is to be used by the project as the controlling and coordinating documentation during future design efforts. Modification and revision of this specification will occur as the design matures, and tiie-Westinghouse MHD Project Manager will be the focal point for maintaining this document and issuing periodic revisions. This document is intended to delineate the power train and-power train components requirements and assumptions that properly reflect the MHD/Steam Power Plant in the PT design. The parameters discussed in this document have been established through system calculations as well as through constraints set by technology and by limitations on materials, cost, physical processes associated with MHD, and the expected operating data for the plant. The specifications listed in this document have precedence over all referenced documents. Where this specification appears to conflict with the requirements of a reference document, such conflicts should be brought to the attention of the Westinghouse MHD Project Manager for resolution.
Robert M. Mayo; Randall L. Mills; M. Nansteel
2002-01-01
The generation of electricity using direct electrostatic and magnetohydrodynamic (MHD) conversion of the plasma-particle energy of small to midsize chemically assisted microwave or glow discharge plasma (CA-plasma) power sources in the range of a few hundred Watts to several tens of kilowatts for microdistributed commercial applications (e.g., household, automotive, light industry, and space-based power) is studied for the first time.
NASA Astrophysics Data System (ADS)
Benyo, Theresa Louise
Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program. One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the exhaust flow from the engine by converting electrical current back into flow enthalpy to increase thrust. Though there has been considerable research into the use of MHD generators to produce electricity for industrial power plants, interest in the technology for flight-weight aerospace applications has developed only recently. In this research, electromagnetic fields coupled with weakly ionzed gases to slow hypersonic airflow were investigated within the confines of an MHD energy-bypass system with the goal of showing that it is possible for an air-breathing engine to transition from takeoff to Mach 7 without carrying a rocket propulsion system along with it. The MHD energy-bypass system was modeled for use on a supersonic turbojet engine. The model included all components envisioned for an MHD energy-bypass system; two preionizers, an MHD generator, and an MHD accelerator. A thermodynamic cycle analysis of the hypothesized MHD energy-bypass system on an existing supersonic turbojet engine was completed. In addition, a detailed thermodynamic, plasmadynamic, and electromagnetic analysis was combined to offer a single, comprehensive model to describe more fully the proper plasma flows and magnetic fields required for successful operation of the MHD energy bypass system. The unique contribution of this research involved modeling the current density, temperature, velocity, pressure, electric field, Hall parameter, and electrical power throughout an annular MHD generator and an annular MHD accelerator taking into account an external magnetic field within a moving flow field, collisions of electrons with neutral particles in an ionized flow field, and collisions of ions with neutral particles in an ionized flow field (ion slip). In previous research, the ion slip term has not been considered. The MHD energy-bypass system model showed that it is possible to expand the operating range of a supersonic jet engine from a maximum of Mach 3.5 to a maximum of Mach 7. The inclusion of ion slip within the analysis further showed that it is possible to 'drive' this system wit
T G Cowling
1962-01-01
Magnetohydrodynamics has applications to the flow of conducting liquids, and to the motion of laboratory and cosmical plasmas, each in the presence of a magnetic field. The application to thermonuclear devices has already been made the subject of a report by A. A. Ware and is only briefly sketched here. The stress in the present report is on the theoretical
Robert C. Murray
2006-01-01
Magnetohydrodynamic (MHD) interactions present a tantalizing opportunity to control hypersonic flows without the need for strong shock waves, high entropy gain, and movable control surfaces. An MHD interaction, however, requires a conductive flowfield. At Mach numbers too low for thermal ionization, flow energies may still be sufficient to justify the cost of an efficient external ionization scheme. In this work,
The Decay of Magnetohydrodynamic Turbulence from Power-Law Initial Conditions
Chirag Kalelkar; Rahul Pandit
2004-01-30
We derive relations for the decay of the kinetic and magnetic energies and the growth of the Taylor and integral scales in unforced, incompressible, homogeneous and isotropic three-dimensional magnetohydrodynamic (3DMHD) turbulence with power-law initial energy spectra. We also derive bounds for the decay of the cross- and magnetic helicities. We then present results from systematic numerical studies of such decay both within the context of an MHD shell model and direct numerical simulations (DNS) of 3DMHD. We show explicitly that our results about the power-law decay of the energies hold for times $t
Oxygen-enriched air for MHD power plants
NASA Technical Reports Server (NTRS)
Ebeling, R. W., Jr.; Cutting, J. C.; Burkhart, J. A.
1979-01-01
Cryogenic air-separation process cycle variations and compression schemes are examined. They are designed to minimize net system power required to supply pressurized, oxygen-enriched air to the combustor of an MHD power plant with a coal input of 2000 MWt. Power requirements and capital costs for oxygen production and enriched air compression for enrichment levels from 13 to 50% are determined. The results are presented as curves from which total compression power requirements can be estimated for any desired enrichment level at any delivery pressure. It is found that oxygen enrichment and recuperative heating of MHD combustor air to 1400 F yields near-term power plant efficiencies in excess of 45%. A minimum power compression system requires 167 MW to supply 330 lb of oxygen per second and costs roughly 100 million dollars. Preliminary studies show MHD/steam power plants to be competitive with plants using high-temperature air preheaters burning gas.
NASA Astrophysics Data System (ADS)
Toth, G.; Daldorff, L. K. S.; Jia, X.; Gombosi, T. I.; Lapenta, G.
2014-12-01
We have recently developed a new modeling capability to embed theimplicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-USmagnetohydrodynamic model. The PIC domain can cover the regions wherekinetic effects are most important, such as reconnection sites. TheBATS-R-US code, on the other hand, can efficiently handle the rest ofthe computational domain where the MHD or Hall MHD description issufficient. As one of the very first applications of the MHD-EPICalgorithm (Daldorff et al. 2014, JCP, 268, 236) we simulate theinteraction between Jupiter's magnetospheric plasma with Ganymede'smagnetosphere, where the separation of kinetic and global scalesappears less severe than for the Earth's magnetosphere. Because theexternal Jovian magnetic field remains in an anti-parallel orientationwith respect to Ganymede's intrinsic magnetic field, magneticreconnection is believed to be the major process that couples the twomagnetospheres. As the PIC model is able to describe self-consistentlythe electron behavior, our coupled MHD-EPIC model is well suited forinvestigating the nature of magnetic reconnection in thisreconnection-driven mini-magnetosphere. We will compare the MHD-EPICsimulations with pure Hall MHD simulations and compare both modelresults with Galileo plasma and magnetic field measurements to assess therelative importance of ion and electron kinetics in controlling theconfiguration and dynamics of Ganymede's magnetosphere.
Evaluation of the ECAS open cycle MHD power plant design
NASA Technical Reports Server (NTRS)
Seikel, G. R.; Staiger, P. J.; Pian, C. C. P.
1978-01-01
The Energy Conversion Alternatives Study (ECAS) MHD/steam power plant is described. The NASA critical evaluation of the design is summarized. Performance of the MHD plant is compared to that of the other type ECAS plant designs on the basis of efficiency and the 30-year levelized cost of electricity. Techniques to improve the plant design and the potential performance of lower technology plants requiring shorter development time and lower development cost are then discussed.
Nonlinear Magnetohydrodynamics
Dieter Biskamp
1997-01-01
This book provides a self-contained introduction to magnetohydrodynamics (MHD), with emphasis on nonlinear processes. The book outlines the conventional aspects of MHD theory, magnetostatic equilibrium and linear stability theory. It concentrates on nonlinear theory, starting with the evolution and saturation of individual ideal and resistive instabilities, continuing with a detailed analysis of magnetic reconnection and concluding with a study of
NASA Technical Reports Server (NTRS)
Wu, S. T.; Song, M. T.; Martens, P. C. H.; Dryer, M.
1991-01-01
A situation wherein a bipolar magnetic field embedded in a stratified solar atmosphere undergoes symmetrical shear motion at the footpoints is investigated via a 2D (nonplanar) MHD simulation. It was found that the vertical plasma flow velocities grow exponentially, leading to a new type of global MHD instability. The growth rate increases almost linearly until it reaches the same order of magnitude as the Alfven speed. Then a nonlinear MHD instability occurs beyond this point. It was found that the central loops are pinched by opposing Lorentz forces, and the outer closed loops stretch upward with the vertically-rising mass flow. The nonlinear dynamical shearing instability is illustrated by a numerical example that is given for three different values of the plasma beta that span several orders of magnitude.
MHD conversion of solar energy. [space electric power system
NASA Technical Reports Server (NTRS)
Lau, C. V.; Decher, R.
1978-01-01
Low temperature plasmas wherein an alkali metal vapor is a component are uniquely suited to simultaneously absorb solar radiation by coupling to the resonance lines and produce electrical power by the MHD interaction. This work is an examination of the possibility of developing space power systems which take advantage of concentrated solar power to produce electricity. It is shown that efficient cycles in which expansion work takes place at nearly constant top cycle temperature can be devised. The power density of the solar MHD generator is lower than that of conventional MHD generators because of the relatively high seed concentration required for radiation absorption and the lower flow velocity permitted to avoid total pressure losses due to heating.
Experimental determination of the MHD-EMP effects on power distribution transformers
McConnell, B.W.; Barnes, P.R. (Oak Ridge National Lab., TN (United States)); Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States))
1991-01-01
It is a well-established fact that geomagnetic storms influence electrical power transmission and distribution systems. Previous cases of such storms in the northern latitudes have resulted in occasional power disruptions, and in some cases, damage to transformers. These effects are caused by a time variation of the earth's magnetic field creating an induced electric field along the surface of the earth. This E-field acts as a voltage source along long power transmission or distribution lines, and if the line is connected to the earth at both ends, a quasi-dc current can flow. This current can cause unwanted saturation in the magnetic cores of transformers in the power system, and this, in turn produces harmonic distortion and transformer heating. This can lead to system upset (shutdown) and possibly transformer burn-out. The detonation of a high altitude nuclear explosion is also known to affect the magnetosphere, producing late-time variations of the earth's magnetic field for several hundreds of seconds. Known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), or E{sub 3}, this environment is of particular concern to electrical power systems in the event of a nuclear attack. Although the MHD-EMP induced currents can be significantly larger in magnitude, they last for a shorter period of time than do those from a geomagnetic storm. The effect of this environment compounds the adverse effects of the early-time high altitude EMP (HEMP) environment, posing a potentially serious threat to the electrical system. The present paper documents an experimental program designed to better understand the behavior of distribution-class transformers subjected to quasi-dc current excitation. Given the knowledge of the MHD-EMP-induced current flowing in a long power line, and the transformer response characteristics obtained in this program, it will be possible to make more accurate assessments of the behavior of the overall power system to EMP. 7 refs., 5 figs.
Berry, G.F.; Minkov, V.; Petrick, M.
1981-11-02
A magnetohydrodynamic (MHD) power generating system is described in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.
NASA Astrophysics Data System (ADS)
Lorzel, Heath
The time-dependent, 2˝-dimensional, axisymmetric, magnetohydrodynamics (MHD) solver MACH2 has been upgraded to include the effects of non-equilibrium air chemistry using the well-established reaction model developed by Park. Several validation cases are presented based on comparisons to the experimentally deduced shock stand-off distance of nitrogen flow over spheres, the shock stand-off distance of spheres fired into air in a ballistic test facility, and the electron number density on the surface of the Ram-C re-entry experiment. In addition, the magnetic induction equation has been upgraded with new verified models that compute the effects of the Hall and ion slip terms. The upgraded code is utilized to model an annular, Hall-type MHD generator that can be employed upstream of a turbojet engine for freestream conditions corresponding to Mach 5 flight at an altitude of 20km. The simulations demonstrate the feasibility of convening inlet kinetic power to storable electric power. Using ionization provided by electron-beam guns and a radial magnetic field B=3T, the generator is shown to produce a maximum of 4.8MW of electric power while reducing the total kinetic power of the flow by 31%. Optimizing the loading parameter, K*Load, across the electrodes demonstrates that the generator could produce 1.54MW of excess electric power that can be stored and used for on-board power requirements. Further, the reduction in flow kinetic power results in an increase in static pressure of 30% and a reduction in stagnation temperature of 3% at the turbojet's compressor inlet that aids the subsequent process of combustion.
Experiments in Magnetohydrodynamics
ERIC Educational Resources Information Center
Rayner, J. P.
1970-01-01
Describes three student experiments in magnetohydrodynamics (MHD). In these experiments, it was found that the electrical conductivity of the local water supply was sufficient to demonstrate effectively some of the features of MHD flowmeters, generators, and pumps. (LC)
A nonvariational code for calculating three-dimensional MHD (magnetohydrodynamic) equilibria
Greenside, H.S.; Reiman, A.H.; Salas, A.
1987-09-01
Details are presented of the PIES code, which uses a nonvariational algorithm for calculating fully three-dimensional MHD equilibria. The MHD equilibrium equations are directly iterated in special coordinates to find self-consistent currents and magnetic fields for given pressure and current profiles and for a given outermost magnetic surface. Three important advantages of this approach over previous methods are the ease with which net current profiles can be imposed, the explicit treatment of resonances, and the ability to handle magnetic islands and stochastic field lines. The convergence properties of the code are studied for several axisymmetric and nonaxisymmetric finite-..beta.. equilibria that have magnetic surfaces. 36 refs., 14 figs., 3 tabs.
Design study of superconducting magnets for a combustion magnetohydrodynamic (MHD) generator
NASA Technical Reports Server (NTRS)
Thome, R. J.; Ayers, J. W.
1977-01-01
Design trade off studies for 13 different superconducting magnet systems were carried out. Based on these results, preliminary design characteristics were prepared for several superconducting magnet systems suitable for use with a combustion driven MHD generator. Each magnet generates a field level of 8 T in a volume 1.524 m (60 in.) long with a cross section 0.254 m x 0.254 m (10 in. x 10 in.) at the inlet and 0.406 m x .406 m (16 in. x 16 in.) at the outlet. The first design involves a racetrack coil geometry intended for operation at 4.2 K; the second design uses a racetrack geometry at 2.0 K; and the third design utilizes a rectangular saddle geometry at 4.2 K. Each case was oriented differently in terms of MHD channel axis and main field direction relative to gravity in order to evaluate fabrication ease. All cases were designed such that the system could be disassembled to allow for alteration of field gradient in the MHD channel by changing the angle between coils. Preliminary design characteristics and assembly drawings were generated for each case.
Computer controlled MHD power consolidation and pulse generation system
Johnson
1988-01-01
The major goal of this research project is to establish the feasibility of a power conversion technology which will permit the direct synthesis of commercial frequency power by means of computer control. The power input to the conversion system is assumed to be a MHD Faraday connected generator which may be viewed as a multi-terminal d.c. source. This consolidation\\/inversion process
Zhu, X. S.; Wang, H. N.; Du, Z. L.; Fan, Y. L., E-mail: xszhu@bao.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
2013-05-10
We undertake an attempt to reconstruct the Sun's non-force-free magnetic field. The solar corona is often considered to be magnetohydrostatic. We solve the full MHD equations with a semi-realistic atmosphere model to attain this stationary state. Our method is tested with a Sun-like model which simulates the emergence of a magnetic flux rope passing from below the photosphere into the corona. Detailed diagnostics shows that our method can model the forced field more successfully than the optimization and potential method, but it still needs to be applied to real data.
MAGNETOHYDRODYNAMIC WAVES AND CORONAL HEATING: UNIFYING EMPIRICAL AND MHD TURBULENCE MODELS
Sokolov, Igor V.; Van der Holst, Bart; Oran, Rona; Jin, Meng; Manchester, Ward B. IV; Gombosi, Tamas I. [Department of AOSS, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States)] [Department of AOSS, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); Downs, Cooper [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States)] [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Roussev, Ilia I. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)] [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Evans, Rebekah M., E-mail: igorsok@umich.edu [NASA Goddard Space Flight Center, Space Weather Lab, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)
2013-02-10
We present a new global model of the solar corona, including the low corona, the transition region, and the top of the chromosphere. The realistic three-dimensional magnetic field is simulated using the data from the photospheric magnetic field measurements. The distinctive feature of the new model is incorporating MHD Alfven wave turbulence. We assume this turbulence and its nonlinear dissipation to be the only momentum and energy source for heating the coronal plasma and driving the solar wind. The difference between the turbulence dissipation efficiency in coronal holes and that in closed field regions is because the nonlinear cascade rate degrades in strongly anisotropic (imbalanced) turbulence in coronal holes (no inward propagating wave), thus resulting in colder coronal holes, from which the fast solar wind originates. The detailed presentation of the theoretical model is illustrated with the synthetic images for multi-wavelength EUV emission compared with the observations from SDO AIA and STEREO EUVI instruments for the Carrington rotation 2107.
NASA Technical Reports Server (NTRS)
Wang, A. H.; Wu, S. T.; Liu, Yang; Hathaway, D.
2008-01-01
We introduce a numerical simulation method for recovering the photospheric velocity field from the vector magnetograms. The traditional method is local correlation tracking (LCT) which is based on measuring the relative displacements of features in blocks of pixels between successive white-light images or magnetograms. Within this method, there are a variety of implementations. One of recently developed implementations is induction local correlation tracking (ILCT) as described by Welsch et al. (2004). They employ the normal component of magnetic induction equation as a constraint to assure consistent solutions. Our numerical method uses the fully three-dimensional MHD equations to recover the photospheric velocity field with individual vector magnetograms. We compare our method to the ILCT method using NOAA AR8210 as an example. The differences and similarities are discussed in detail.
Advanced superconducting MHD magnet design for a retrofit power plant
P. G. Marston; J. R. Hale; A. M. Dawson
1989-01-01
A magnet system has been designed for an MHD topping cycle retrofit of a conventional power plant. The channel power output wil be --35 MWe. The 4.5 T peak on-axis field magnet will be constructed of an unusual NbTi superconductor wound into four subunits per dipole half. These will be three 45Â° saddle coils with circular or ellipsoidal end turns
Pamir-3U pulsed portable MHD power system
Zeigarnik, V.A. [IVTAN-Association of Russian Academy of Sciences, Moscow (Russian Federation); Swallom, D.W.; Gibbs, J.S. [Textron Defense Systems, Everett, MA (United States)
1994-12-31
The results of the development of a portable, pulsed MHD power system, called the Pamir-3U, are presented. The maximum operating parameters of the Pamir-3U MHD power system are a net power output of 15 MW and a maximum duration of the electrical pulse at the load of 10 seconds. The work is being performed by the {open_quotes}IVTAN - Association{close_quotes} of the Russian Academy of Sciences (Russia) and Textron Defense Systems (USA). Major subcontractors also participating in this effort are Nizhny Novgorod Machine Building Plant (Russia), Lubertsy Scientific and Production Association (Russia) and Aerojet Corporation (USA). Textron Defense Systems is the prime contractor with overall management and systems integration of the project. Aerojet Corporation will provide the test site and perform the acceptance test program. The Russian subcontract team is led by IVTAN, who is responsible for the overall design and integration of the Pamir-3U System and the electrical control and data acquisition. The two subcontractors working for IVTAN are responsible for the magnets, channels, and electrical equipment (Nizhny Novgorod) and the plasma generators (Lubertsy). The Pamir-3U MHD system is a portable power system that can be transported to various operational locations. The power system is self-contained and does not require extensive support equipment to generate the design power.
Adaptive Mesh Refinement for Global Magnetohydrodynamic Simulation
Stout, Quentin F.
Adaptive Mesh Refinement for Global Magnetohydrodynamic Simulation Tamas I. Gombosi, Darren L. De environment. Presently, and in the foreseeable future, magnetohydrodynamic (MHD) mod- els are the only models Non-relativistic Magnetohydrodynamics The governing equations for an ideal, non
NASA Astrophysics Data System (ADS)
Murray, Robert C.
Magnetohydrodynamic (MHD) interactions present a tantalizing opportunity to control hypersonic flows without the need for strong shock waves, high entropy gain, and movable control surfaces. An MHD interaction, however, requires a conductive flowfield. At Mach numbers too low for thermal ionization, flow energies may still be sufficient to justify the cost of an efficient external ionization scheme. In this work, MHD power is extracted from cold, supersonic air using short-duration, high-repetition-rate, high-voltage pulses (2 ns, 100 kHz, 5 kV/cm) to ionize a cold, Mach 3 (600 m/sec), 0.04 kg/m 3 flow. A few tens of milliwatts were extracted from the 3 cm cube region of ionization, which scales to hundreds of kilowatts of power in higher velocity, larger scale devices that would be appropriate for flight applications. Because the electrical pulses used to ionize the flow greatly exceed the breakdown threshold, the efficiency of the pulsed ionization scheme is expected to greatly exceed that of DC, or steady RF discharges. To determine the ionization efficiency, two diagnostic methods were developed. A microwave diagnostic technique, capable of measuring both the electron number density and electron collision frequency in small scale, weakly ionized, cold plasmas was developed for measurements in the pulser-generated plasmas. The technique involved broadcasting extraordinary waves through the plasma. By varying the intensity of an applied magnetic field, the upper hybrid resonance of extraordinary microwave propagation was shifted over a range of electron number densities. Electron number densities and collision frequencies were then determined based on the conditions corresponding to a complete cessation of microwave transmission across the plasma. Number densities in the range of 5 x 1011 per cm3 at collision frequencies in the neighborhood of 5 to 10 GHz are reported for measurements in a static discharge cell at conditions comparable to the supersonic MHD channel. Power measurements via the Current/Voltage characteristics of the pulser driven discharge were investigated using Fourier analysis of multiple signals from several measurement points in the experiment. Combining these measurements with the aforementioned electron number densities yielded efficiencies of electron generation in the range of 70 to 170 eV per electron.
The Magnetohydrodynamics of Supersonic Gas Clouds: MHD Cosmic Bullets and Wind-swept Clumps
NASA Astrophysics Data System (ADS)
Jones, T. W.; Ryu, Dongsu; Tregillis, I. L.
1996-12-01
We report an extensive set of two-dimensional MHD simulations exploring the role and evolution of magnetic fields in the dynamics of supersonic plasma clumps. We examine the influence of both ambient field strength and orientation on the problem. Of those two characteristics, field orientation is far more important in the cases we have considered with ?0 = Pg/Pb ? 1. That is due to the geometry-sensitivity of field stretching/amplification from large-scale shearing motions around the bullet When the ambient magnetic field is transverse to the bullet motion, even a very modest field, well below equipartition strength, can be amplified by field line stretching around the bullet within a couple of bullet crushing times so that Maxwell stresses become comparable to the ram pressure associated with the bullet motion. The possibility is discussed that those situations might lead to large, induced electric potentials capable of accelerating charged particles. When the ambient field is aligned to the bullet motion, on the other hand, reconnection-prone topologies develop that shorten the stretched field and release much of the excess energy it contains. In this geometry, the Maxwell stresses on the bullet never approach the ram pressure level. In both cases, however, the presence of a field with even moderate initial strength acts to help the flow realign itself around the bullet into a smoother, more laminar form. That reduces bullet fragmentation tendencies caused by destructive instabilities. Eddies seem less effective at field amplification than flows around the bullet, because fields within eddies tend to be expelled to the eddy perimeters. Similar effects cause the magnetic field within the bullet itself to be reduced below its initial value over time. For oblique fields, we expect that the transverse field cases modeled here are more generally relevant What counts is whether field lines threading the face of the bullet are swept around it in a fashion that folds them (leading to reconnection) or that keeps them unidirectional one each side of the bullet. In the second instance, behaviors should resemble those of the transverse field cases. We estimate that this quasi-transverse behavior is appropriate whenever the angle, 0, between the motion and the field satisfies tan ? ? 1/M, where M is the bullet Mach number. From these simulations, we find support in either field geometry for the conclusions reached in previous studies that nonthermal radio emission associated with supersonic clumps is likely to be controlled largely by the generation of strong magnetic fields around the perimeters of the clumps, rather than local particle acceleration and field compression within the bow shock. In addition, since the magnetic pressure on the nose of the bullet likely becomes comparable to the ram pressure and hence the total pressure behind the bow shock, the gas pressure there could be substantially lower than that in a gasdynamical bullet That means, as well, that the temperature in the region on the nose of the bullet would be lower than that predicted in the gasdynamical case. That detail could alter expectations of the thermal emission, including X-rays and UV-IR lines.
Magnetohydrodynamic Turbulence
Dieter Biskamp
2003-01-01
After a brief outline of magnetohydrodynamic theory, this introductory book discusses the macroscopic aspects of MHD turbulence, and covers the small-scale scaling properties. Applications are provided for astrophysical and laboratory systems. Magnetic turbulence is the natural state of most astrophysical systems, such as stellar convection zones, stellar winds or accretion discs. It is also found in laboratory devices, most notably
Impinging jet separators for liquid metal magnetohydrodynamic power cycles
NASA Technical Reports Server (NTRS)
Bogdanoff, D. W.
1973-01-01
In many liquid metal MHD power, cycles, it is necessary to separate the phases of a high-speed liquid-gas flow. The usual method is to impinge the jet at a glancing angle against a solid surface. These surface separators achieve good separation of the two phases at a cost of a large velocity loss due to friction at the separator surface. This report deals with attempts to greatly reduce the friction loss by impinging two jets against each other. In the crude impinging jet separators tested to date, friction losses were greatly reduced, but the separation of the two phases was found to be much poorer than that achievable with surface separators. Analyses are presented which show many lines of attack (mainly changes in separator geometry) which should yield much better separation for impinging jet separators).
Experiments on H2-O2MHD power generation
NASA Technical Reports Server (NTRS)
Smith, J. M.
1980-01-01
Magnetohydrodynamic power generation experiments utilizing a cesium-seeded H2-O2 working fluid were carried out using a diverging area Hall duct having an entrance Mach number of 2. The experiments were conducted in a high-field strength cryomagnet facility at field strengths up to 5 tesla. The effects of power takeoff location, axial duct location within the magnetic field, generator loading, B-field strength, and electrode breakdown voltage were investigated. For the operating conditions of these experiments, it is found that the power output increases with the square of the B-field and can be limited by choking of the channel or interelectrode voltage breakdown which occurs at Hall fields greater than 50 volts/insulator. Peak power densities of greater than 100 MW/cu M were achieved.
Statistics of passive tracers in three-dimensional magnetohydrodynamic turbulence
Schmidt, Matthias
Statistics of passive tracers in three-dimensional magnetohydrodynamic turbulence Angela Busse; accepted 7 November 2007; published online 13 December 2007 Magnetohydrodynamic MHD turbulence is studied
Shell to shell energy transfer in magnetohydrodynamic dynamo simulations
Pouquet, Annick
Shell to shell energy transfer in magnetohydrodynamic dynamo simulations Pablo Mininni, Alexandros of magnetic fields in astronomical objects. In the magnetohydrodynamic (MHD) dynamo, an initially small
Magnetohydrodynamic turbulence: Observation and experimenta)
NASA Astrophysics Data System (ADS)
Brown, M. R.; Schaffner, D. A.; Weck, P. J.
2015-05-01
We provide a tutorial on the paradigms and tools of magnetohydrodynamic (MHD) turbulence. The principal paradigm is that of a turbulent cascade from large scales to small, resulting in power law behavior for the frequency power spectrum for magnetic fluctuations EB(f ) . We will describe five useful statistical tools for MHD turbulence in the time domain: the temporal autocorrelation function, the frequency power spectrum, the probability distribution function of temporal increments, the temporal structure function, and the permutation entropy. Each of these tools will be illustrated with an example taken from MHD fluctuations in the solar wind. A single dataset from the Wind satellite will be used to illustrate all five temporal statistical tools.
Anisotropic magnetohydrodynamic spectral transfer in the diffusion approximation W. H. Matthaeus,1
Oughton, Sean
Anisotropic magnetohydrodynamic spectral transfer in the diffusion approximation W. H. Matthaeus,1 2009 A theoretical model of spectral transfer for anisotropic magnetohydrodynamic MHD turbulence spectral transport closure to magnetohydrodynamics MHD in which anisotropy is in- duced by a large
MHD Power Generation Prospects for Commercial and Space Applications
W. Steve Shepard
1987-01-01
(MHD)processto commercial power toriscombined witha conventional steampowerplant. generation. The UnitedStatesDepartment of EnergyA schematic oftheconventional steamplantisshownin (DOE)hasspentapproximately $500milliononresearchFigure1. A schematic oftheproposed MHDsystemis relatedto commerical MHDpowergeneration. At its showninFigure 2. TheMHDportionofthecycle, from peakthebudgetwas $70millionperyear. TheDOE the combustor to the exitof thediffuser, is the budgetforMHDduringthe1986fiscal yearwasapproxi-topping cycle, andtherestofthecomponents arethe mately$28.5millionaftertheGramm-Ruddman-Hollings bottoming cycle.Notethata conventional powerplant formula wasapplied tothe1985budget. is justan atmospheric coalcombustor connected to
MHD micropumping of power-law fluids: A numerical solution
NASA Astrophysics Data System (ADS)
Moghaddam, Saied
2013-02-01
The performance of MHD micropumps is studied numerically assuming that the viscosity of the fluid is shear-dependent. Using power-law model to represent the fluid of interest, the effect of power-law exponent, N, is investigated on the volumetric flow rate in a rectangular channel. Assuming that the flow is laminar, incompressible, two-dimensional, but (approximately) unidirectional, finite difference method (FDM) is used to solve the governing equations. It is found that shear-thinning fluids provide a larger flow rate as compared to Newtonian fluids provided that the Hartmann number is above a critical value. There exists also an optimum Hartmann number (which is larger than the critical Hartmann number) at which the flow rate is maximum. The power-law exponent, N, strongly affects the optimum geometry depending on the Hartmann number being smaller or larger than the critical Hartmann number.
Experiments on H2-O2 MHD power generation
NASA Technical Reports Server (NTRS)
Smith, J. M.
1980-01-01
MHD power generation experiments utilizing a cesium-seeded H2-O2 working fluid have been carried out using a diverging area Hall duct having an entrance Mach number of 2. The experiments are conducted in a high-field strength cryomagnet facility at field strengths up to 5 tesla. The effects of power takeoff location, axial duct location within the magnetic field, generator loading, B-field strength, and electrode breakdown voltage were investigated. For the operating conditions of these experiments it is found that the power output increases with the square of the B-field and can be limited by choking of the channel or interelectrode voltage breakdown which occurs at Hall fields greater than 50 volts/insulator.
Stability of open-cycle MHD generation system connected to power transmission line
Nobuhiko Hayanose; Yoshitaka Inui; Motoo Ishikawa; Juro Umoto
1998-01-01
The stability of the binary combined system of an MHD generator and a synchronous generator, including inverter and power transmission system, is studied numerically. The binary combined power generation system is a pilot plant scale with thermal input of about 110MW and consists of a MHD generator as a topping cycle and a steam turbine generator as a bottoming cycle.
Government research and development summaries: Magnetohydrodynamic project briefs. Irregular
NONE
1995-03-01
Magnetohydrodynamic Project Briefs describe the status of all R and D programs submitted to the Power Information Center by the government sponsors in energy conversion involving the magnetohydrodynamic (MHD) interaction between electromagnetic fields and electrically conducting fields, including fuels, materials, plasma dynamics, and combustion. The document is not to be reproduced, in whole or in part, for dissemination outside your own organization nor may it be reproduced for advertising or sales promotion purposes.
Gyroscopic analog for magnetohydrodynamics
Holm, D.D.
1982-07-20
The gross features of plasma equilibrium and dynamics in the ideal magnetohydrodynamics (MHD) model can be understood in terms of a dynamical system which closely resembles the equations for a deformable gyroscope.
Gyroscopic analog for magnetohydrodynamics
Holm, D.D.
1981-01-01
The gross features of plasma equilibrium and dynamics in the ideal magnetohydrodynamics (MHD) model can be understood in terms of a dynamical system which closely resembles the equations for a deformable gyroscope.
NASA Technical Reports Server (NTRS)
Riggins, David W.
2002-01-01
The performance of the MHD energy bypass air-breathing engine for high-speed propulsion is analyzed in this investigation. This engine is a specific type of the general class of inverse cycle engines. In this paper, the general relationship between engine performance (specific impulse and specific thrust) and the overall total pressure ratio through an engine (from inlet plane to exit plane) is first developed and illustrated. Engines with large total pressure decreases, regardless of cause or source, are seen to have exponentially decreasing performance. The ideal inverse cycle engine (of which the MHD engine is a sub-set) is then demonstrated to have a significant total pressure decrease across the engine; this total pressure decrease is cycle-driven, degrades rapidly with energy bypass ratio, and is independent of any irreversibility. The ideal MHD engine (inverse cycle engine with no irreversibility other than that inherent in the MHD work interaction processes) is next examined and is seen to have an additional large total pressure decrease due to MHD-generated irreversibility in the decelerator and the accelerator. This irreversibility mainly occurs in the deceleration process. Both inherent total pressure losses (inverse cycle and MHD irreversibility) result in a significant narrowing of the performance capability of the MHD bypass engine. The fundamental characteristics of MHD flow acceleration and flow deceleration from the standpoint of irreversibility and second-law constraints are next examined in order to clarify issues regarding flow losses and parameter selection in the MM modules. Severe constraints are seen to exist in the decelerator in terms of allowable deceleration Mach numbers and volumetric (length) required for meaningful energy bypass (work interaction). Considerable difficulties are also encountered and discussed due to thermal/work choking phenomena associated with the deceleration process. Lastly, full engine simulations utilizing inlet shock systems, finite-rate chemistry, wall cooling with thermally balanced engine (fuel heat sink), fuel injection and mixing, friction, etc. are shown and discussed for both the MHD engine and the conventional scramjet. The MHD bypass engine has significantly lower performance in all categories across the Mach number range (8 to 12.2). The lower performance is attributed to the combined effects of 1) additional irreversibility and cooling requirements associated with the MHD components and 2) the total pressure decrease associated with the inverse cycle itself.
Computer controlled MHD power consolidation and pulse generation system
Johnson, R.; Marcotte, K.; Donnelly, M.
1990-01-01
The major goal of this research project is to establish the feasibility of a power conversion technology which will permit the direct synthesis of computer programmable pulse power. Feasibility has been established in this project by demonstration of direct synthesis of commercial frequency power by means of computer control. The power input to the conversion system is assumed to be a Faraday connected MHD generator which may be viewed as a multi-terminal dc source and is simulated for the purpose of this demonstration by a set of dc power supplies. This consolidation/inversion (CI), process will be referred to subsequently as Pulse Amplitude Synthesis and Control (PASC). A secondary goal is to deliver a controller subsystem consisting of a computer, software, and computer interface board which can serve as one of the building blocks for a possible phase II prototype system. This report period work summarizes the accomplishments and covers the high points of the two year project. 6 refs., 41 figs.
Reconnection events in two-dimensional Hall magnetohydrodynamic S. Donato,1
Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence S. Donato,1 S. Servidio performed by comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics reconnection in 2D Hall magnetohydrodynamic (HMHD) tur- bulence. Using high resolution pseudo
Analytical and numerical approaches to structure functions in magnetohydrodynamic turbulence
Grauer, Rainer
Analytical and numerical approaches to structure functions in magnetohydrodynamic turbulence Rainer¨usseldorf, D--40225 D¨usseldorf, Germany January 8, 1996 Abstract In magnetohydrodynamic turbulence in strongly turbulent systems. 1 Introduction Magnetohydrodynamic (MHD) turbulence offers a possibility
A class of resistive axisymmetric magnetohydrodynamic equilibria in a periodic
Galgani, Luigi
A class of resistive axisymmetric magnetohydrodynamic equilibria in a periodic cylinder Antonio of visco-resistive incompressible magnetohydrodynamics in a periodic cylinder, with boundary conditions approximation dynamical systems such as the equations of magnetohydrodynamics (MHD). Most often, ideal or non
Engineering support for magnetohydrodynamic power plant analysis and design studies
NASA Technical Reports Server (NTRS)
Carlson, A. W.; Chait, I. L.; Marchmont, G.; Rogali, R.; Shikar, D.
1980-01-01
The major factors which influence the economic engineering selection of stack inlet temperatures in combined cycle MHD powerplants are identified and the range of suitable stack inlet temperatures under typical operating conditions is indicated. Engineering data and cost estimates are provided for four separately fired high temperature air heater (HTAH) system designs for HTAH system thermal capacity levels of 100, 250, 500 and 1000 MWt. An engineering survey of coal drying and pulverizing equipment for MHD powerplant application is presented as well as capital and operating cost estimates for varying degrees of coal pulverization.
MHD Energy Bypass Scramjet Engine
NASA Technical Reports Server (NTRS)
Mehta, Unmeel B.; Bogdanoff, David W.; Park, Chul; Arnold, Jim (Technical Monitor)
2001-01-01
Revolutionary rather than evolutionary changes in propulsion systems are most likely to decrease cost of space transportation and to provide a global range capability. Hypersonic air-breathing propulsion is a revolutionary propulsion system. The performance of scramjet engines can be improved by the AJAX energy management concept. A magneto-hydro-dynamics (MHD) generator controls the flow and extracts flow energy in the engine inlet and a MHD accelerator downstream of the combustor accelerates the nozzle flow. A progress report toward developing the MHD technology is presented herein. Recent theoretical efforts are reviewed and ongoing experimental efforts are discussed. The latter efforts also include an ongoing collaboration between NASA, the US Air Force Research Laboratory, US industry, and Russian scientific organizations. Two of the critical technologies, the ionization of the air and the MHD accelerator, are briefly discussed. Examples of limiting the combustor entrance Mach number to a low supersonic value with a MHD energy bypass scheme are presented, demonstrating an improvement in scramjet performance. The results for a simplified design of an aerospace plane show that the specific impulse of the MHD-bypass system is better than the non-MHD system and typical rocket over a narrow region of flight speeds and design parameters. Equilibrium ionization and non-equilibrium ionization are discussed. The thermodynamic condition of air at the entrance of the engine inlet determines the method of ionization. The required external power for non-equilibrium ionization is computed. There have been many experiments in which electrical power generation has successfully been achieved by magneto-hydrodynamic (MHD) means. However, relatively few experiments have been made to date for the reverse case of achieving gas acceleration by the MHD means. An experiment in a shock tunnel is described in which MHD acceleration is investigated experimentally. MHD has several potential aerospace applications. The first is to improve the performance of hypersonic air-breathing engines for space launch and cruise vehicles. The second is to improve the performance of a high enthalpy wind tunnel. The third is to control a hypersonic vehicle. With such applications in mind, theoretical and experiments are being conducted at the NASA Ames Research Center to develop the MHD technology.
Lattice Boltzmann Magnetohydrodynamics
Daniel O. Martinez; Shiyi Chen; William H. Matthaeus
1994-01-01
Lattice gas and lattice Boltzmann methods are recently developed numerical schemes for simulating a variety of physical systems. In this paper a new lattice Boltzmann model for modeling two-dimensional incompressible magnetohydrodynamics (MHD) is presented. The current model fully utilizes the flexibility of the lattice Boltzmann method in comparison with previous lattice gas and lattice Boltzmann MHD models, reducing the number
Advanced LMMHD space power generation concept
Vincent Ho; Albert Wong; Kilyoo Kim; Vijay Dhir
1987-01-01
Magnetohydrodynamic (MHD) power generation concept has been proposed and studied worldwide as one of the future power generation sources. An advanced one fluid two phase liquid metal (LM) MHD power generation concept was developed for space nuclear power generation design. The concept employs a nozzle to accelerate the liquid metal coolant to an acceptable velocity with Mach number greater than
Downstream component corrosion in coal-fired MHD power plants
White, M. K.
1980-06-01
Results are given to date of corrosion probe studies conducted to evaluate the nature and severity of degradation of oiler and superheater materials in coal-fired MHD power generation systems. Tests were conducted with two air or nitrogen cooled probes in Cell III of the UTSI MHD facility. One probe had carbon steel samples subjected to metal temperatures of from 547K to 719K and reducing (SR = 0.85) gas conditions to simulate boiler tube conditions. The exposure time to date on these samples is 240 minutes. The other probe had samples of carbon steel, chromium-molybdenum steels and stainless steels subjected to temperatures ranging from 811K to 914K with oxidizing (SR = 1.15) gas conditions. The total run time on these samples was 70 minutes. The boiler probe samples were found to undergo predominantly pitted type corrosion beneath a deposit of ash/seed material having approximately 34% K/sub 2/SO/sub 4/. Weight loss rates varied from about 1.5 x 10/sup -4/ gm/hr-cm/sup 2/ at the cool end of the probe to about 5.5 x 10/sup -4/ gm/hr-cm/sup 2/ at the hot end. This loss is attributed primarily to sulfidation by hydrogen sulfide. Resistance to scaling of superheater materials increased progressively with the degree of alloying. Attack appeared to be in the form of surface scales containing mixtures of oxides and is attributed to either gaseous oxidation or to the presence of complex potassium trisulfates.
Magnetohydrodynamic power generation. Quarterly report, March 1May 31, 1984
R. H. Eustis; C. H. Kruger; M. Mitchner; S. A. Self
1984-01-01
Secondary flow driven by Lorentz forces in an MHD channel has recently been the subject of considerable interest. Several theoretical studies have indicated that secondary flow may be a significant factor in generator performance. Recently we have performed direct measurements of the secondary flow field over a downstream cross-plane of the M-2 channel. The velocity measurements were performed using laser
Parametric study of potential early commercial MHD power plants
NASA Technical Reports Server (NTRS)
Hals, F. A.
1979-01-01
Three different reference power plant configurations were considered with parametric variations of the various design parameters for each plant. Two of the reference plant designs were based on the use of high temperature regenerative air preheaters separately fired by a low Btu gas produced from a coal gasifier which was integrated with the power plant. The third reference plant design was based on the use of oxygen enriched combustion air preheated to a more moderate temperature in a tubular type metallic recuperative heat exchanger which is part of the bottoming plant heat recovery system. Comparative information was developed on plant performance and economics. The highest net plant efficiency of about 45 percent was attained by the reference plant design with the use of a high temperature air preheater separately fired with the advanced entrained bed gasifier. The use of oxygen enrichment of the combustion air yielded the lowest cost of generating electricity at a slightly lower plant efficiency. Both of these two reference plant designs are identified as potentially attractive for early MHD power plant applications.
Generation of compressible modes in MHD turbulence
Jungyeon Cho; A. Lazarian
2005-01-01
Astrophysical turbulence is magnetohydrodynamic (MHD) in nature. We discuss fundamental properties of MHD turbulence and in particular the generation of compressible MHD waves by Alfvénic 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: Alfvén, slow,
Cascade model for intermittency in fully developed magnetohydrodynamic turbulence
Vincenzo Carbone
1993-01-01
Evidence of intermittency in the interplanetary space plasma has been recently pointed out. We present a magnetohydrodynamic (MHD) cascade model, derived from a binomial process, whose results fit the observed scaling law for the qth power of the structure functions. Using this model we modify the oldest Kraichnan theory showing, for the first time, the multifractal structure of fully developed
Advanced superconducting MHD magnet design for a retrofit power plant
Marston, P.G.; Hale, J.R.; Dawson, A.M.
1989-03-01
A magnet system has been designed for an MHD topping cycle retrofit of a conventional power plant. The channel power output wil be --35 MWe. The 4.5 T peak on-axis field magnet will be constructed of an unusual NbTi superconductor wound into four subunits per dipole half. These will be three 45/sup 0/ saddle coils with circular or ellipsoidal end turns and a single planar coil with a modified racetrack shape that will serve principally as a field shaping coil. This planar coil also enables a substantial reduction in the ratio of peak to central field strength. Among the unique features of this design will be the use of flexible bands in tension as the primary element of the transverse force containment structure. The conductor will be of the cable-in-conduit type with a low copper-to-superconductor ratio cable and a thick-walled aluminum conduit sheath. The sheath will support the axial loads on the saddles and will also provide thermal mass for protection against overheating in the event of an energy dump. The analysis and design of this magnet system and its projected advantages in both performance and economics are discussed.
Parametric study of potential early commercial power plants Task 3-A MHD cost analysis
NASA Technical Reports Server (NTRS)
1983-01-01
The development of costs for an MHD Power Plant and the comparison of these costs to a conventional coal fired power plant are reported. The program is divided into three activities: (1) code of accounts review; (2) MHD pulverized coal power plant cost comparison; (3) operating and maintenance cost estimates. The scope of each NASA code of account item was defined to assure that the recently completed Task 3 capital cost estimates are consistent with the code of account scope. Improvement confidence in MHD plant capital cost estimates by identifying comparability with conventional pulverized coal fired (PCF) power plant systems is undertaken. The basis for estimating the MHD plant operating and maintenance costs of electricity is verified.
A summary of the ECAS MHD power plant results
NASA Technical Reports Server (NTRS)
Seikel, G. R.; Harris, L. P.
1976-01-01
The performance and the cost of electricity (COE) for MHD systems utilizing coal or coal derived fuels are summarized along with a conceptual open cycle MHD plant design. The results show that open cycle coal fired recuperatively preheated MHD systems have potentially one of the highest coal-pile-to-bus bar efficiencies (48.3%) and also one of the lowest COE of the systems studied. Closed cycle, inert gas systems do not appear to have the potential of exceeding the efficiency of or competing with the COE of advanced steam plants.
A numerical study of the alpha model for two-dimensional magnetohydrodynamic turbulent flows
Pouquet, Annick
A numerical study of the alpha model for two-dimensional magnetohydrodynamic turbulent flows Pablo the "Lagrangian-averaged" model, for two-dimensional incompressible magnetohydrodynamic (MHD) turbulence
TWO-FLUID MAGNETOHYDRODYNAMIC CYCLE FOR NUCLEAR-ELECTRIC POWER CONVERSION
1962-01-01
To circumvent the high temperatures required in a magnetohydrodynamic ; power conversion system employing a plasma as the conductor, it is proposed that ; a liquid metal be employed as the conductor, the metal being accelerated by the ; vapor of a second fluid in a two-phase nozzle and extracted by a liquid-gas ; separator. It is estimated that a
Results from the Pamir-3U pulsed portable MHD power system program
Swallom, D.W.; Goldfarb, V.M.; Gibbs, J.S. [Textron Systems Division, Wilmington, MA (United States)] [and others
1996-12-31
The Pamir-3U MHD Power System Acceptance Test Program was successfully performed in the United States in 1995. The Pamir-3U MHD system is a portable power system that can be transported to various operational locations. The power system is self-contained and does not require extensive support equipment to generate the design power. The work was performed by the IVTAN-Association of the Russian Academy of Sciences (Russia) and Textron Systems Division (US). Major subcontractors that participated in this effort are Nizhny Novgorod Machine Building Plant (Russia), Federal Center of Dual Technologies Soyuz (Russia) and Aerojet Corporation (US). A preliminary acceptance test program, consisting of five power tests and several preliminary tests, was conducted during August 1994 at Geodesiya Research and Development Institute, Krasnoarmejsk, Russia. During this test program, power levels as high as 15 MW(e) were obtained. Operation of the facility in various operating modes was demonstrated, and several tests were conducted where the resistance was varied during the hot-fire test run. For the final Pamir-3U MHD Power System Acceptance Test Program, eight hot-fire tests were performed. The performance levels of the Pamir-3U MHD Power System were confirmed during these tests. As a result of the experiments performed, the operational ability of the Pamir-3U MHD power system to operate in a variety of performance modes and under a variety of operating conditions was confirmed.
NASA Technical Reports Server (NTRS)
Wu, S. T.; Guo, W. P.
1997-01-01
We present results for an investigation of the interaction of a helmet streamer arcade and a helical flux-rope emerging from the sub-photosphere. These results are obtained by using a three-dimensional axisymmetric, time-dependent ideal magnetohydrodynamic (MHD) model. Because of the physical nature of the flux-rope, we investigate two types of flux-ropes; (1) high density flux-rope (i.e. flux-rope without cavity), and (2) low density flux rope (i.e. flux-rope with cavity). When the streamer is disrupted by the flux-rope, it will evolve into a configuration resembling the typical observed loop-like Coronal Mass Ejection (CMES) for both cases. The streamer-flux rope system with cavity is easier to be disrupted and the propagation speed of the CME is faster than the streamer-flux rope system without cavity. Our results demonstrate that magnetic buoyancy force plays an important role in disrupting the streamer.
Ultrahigh temperature vapor core reactor-MHD system for space nuclear electric power
NASA Technical Reports Server (NTRS)
Maya, Isaac; Anghaie, Samim; Diaz, Nils J.; Dugan, Edward T.
1991-01-01
The conceptual design of a nuclear space power system based on the ultrahigh temperature vapor core reactor with MHD energy conversion is presented. This UF4 fueled gas core cavity reactor operates at 4000 K maximum core temperature and 40 atm. Materials experiments, conducted with UF4 up to 2200 K, demonstrate acceptable compatibility with tungsten-molybdenum-, and carbon-based materials. The supporting nuclear, heat transfer, fluid flow and MHD analysis, and fissioning plasma physics experiments are also discussed.
NASA Astrophysics Data System (ADS)
Dehghan, Mehdi; Salehi, Rezvan
2013-12-01
In this paper a meshfree weak-strong (MWS) form method is considered to solve the coupled equations in velocity and magnetic field for the unsteady magnetohydrodynamic flow throFor this modified estimaFor this modified estimaFor this modified estimaugh a pipe of rectangular and circular sections having arbitrary conducting walls. Computations have been performed for various Hartman numbers and wall conductivity at different time levels. The MWS method is based on applying a meshfree collocation method in strong form for interior nodes and nodes on the essential boundaries and a meshless local Petrov-Galerkin method in weak form for nodes on the natural boundary of the domain. In this paper, we employ the moving least square reproducing kernel particle approximation to construct the shape functions. The numerical results for sample problems compare very well with steady state solution and other numerical methods.
The first experiments with Pamir-3U pulsed portable MHD power system
Zeigarnik, V.A.; Aitov, N.A.; Okunev, V.I. [IVTAN-Association of the Russian Academy of Sciences, Moscow (Russian Federation)] [and others
1995-12-31
The results of the first experiments with a portable, pulsed MHD Power System, called the Pamir-3U, performed in Russia in 1994 are presented and discussed. The Pamir-3U MHD system is a portable power system that can be transported to various operational locations. The power system is self-contained and does not require extensive support equipment to generate the design power. The work is being performed by the IVTAN-Association of the Russian Academy of Sciences (Russia) and Textron Defense Systems (USA). Major subcontractors also participating in this effort are Nizhny Novgorod Machine Building Plant (Russia), Lubertsy Scientific and Production Association Soyuz (Russia) and Aerojet Corporation (USA). Five hot-fire tests were performed for the adjustment of the components of the Pamir-3U MHD Power System and for the demonstration of the Pamir-3U MM Power System operating parameters. Correspondence of the operating performance to the requirements of the technical assignment document was also demonstrated. The following output parameters of the Pamir-3U MHD power system were obtained during the hot-fire tests: (1) nominal output power - 10-15 MW{sub e}; (2) maximal output power - 15.1 MW{sub e}; and (3) maximal current pulse duration in the load - 7.15 s. The performance output of the Pamir-3U Power System satisfied the primary requirements of the technical assignment document.
Conditions for sustainment of magnetohydrodynamic turbulence driven by Alfven waves*
Oughton, Sean
Conditions for sustainment of magnetohydrodynamic turbulence driven by Alfve´n waves* P. Dmitruk, turbulence is driven by the supply of wave energy. In the context of incompressible magnetohydrodynamics MHD by the equations of magnetohydrodynamics MHD . It is not an infrequent circumstance that turbulence is driven
A two-component phenomenology for homogeneous magnetohydrodynamic S. Oughtona
Oughton, Sean
A two-component phenomenology for homogeneous magnetohydrodynamic turbulence S. Oughtona Department in three-dimensional magnetohydrodynamic MHD turbulence is developed. The model allows for influence-point correlation function2 or related models with specified conser- vation properties.5 Magnetohydrodynamics MHD
Magnetohydrodynamic fluidic system
Lee, Abraham P.; Bachman, Mark G.
2004-08-24
A magnetohydrodynamic fluidic system includes a reagent source containing a reagent fluid and a sample source containing a sample fluid that includes a constituent. A reactor is operatively connected to the supply reagent source and the sample source. MHD pumps utilize a magnetohydrodynamic drive to move the reagent fluid and the sample fluid in a flow such that the reagent fluid and the sample fluid form an interface causing the constituent to be separated from the sample fluid.
Exploratory study of several advanced nuclear-MHD power plant systems.
NASA Technical Reports Server (NTRS)
Williams, J. R.; Clement, J. D.; Rosa, R. J.; Yang, Y. Y.
1973-01-01
In order for efficient multimegawatt closed cycle nuclear-MHD systems to become practical, long-life gas cooled reactors with exit temperatures of about 2500 K or higher must be developed. Four types of nuclear reactors which have the potential of achieving this goal are the NERVA-type solid core reactor, the colloid core (rotating fluidized bed) reactor, the 'light bulb' gas core reactor, and the 'coaxial flow' gas core reactor. Research programs aimed at developing these reactors have progressed rapidly in recent years so that prototype power reactors could be operating by 1980. Three types of power plant systems which use these reactors have been analyzed to determine the operating characteristics, critical parameters and performance of these power plants. Overall thermal efficiencies as high as 80% are projected, using an MHD turbine-compressor cycle with steam bottoming, and slightly lower efficiencies are projected for an MHD motor-compressor cycle.
Vlad, Gregorio
Hybrid magnetohydrodynamic-particle simulation of linear and nonlinear evolution of Alfve´n modes MHD-particle simulation code, which solves the coupled set of MHD magnetohydrodynamic equations) coordinates, ideal magnetohydrodynamic MHD shear-Alfve´n oscillations have a continuous frequency spec- trum 2
Renormalization group in magnetohydrodynamic turbulence S. J. Camargo and H. Tasso
Camargo, Suzana J.
Renormalization group in magnetohydrodynamic turbulence S. J. Camargo and H. Tasso Max to magnetohydrodynamic (MHD) equations written in Elshser variables, as done by Yakhot and Orszag for Navier contain mag- netic fields and are described by magnetohydrodynamic (MHD) equations. MHD turbulence occurs
LOCALLY DIVERGENCE-PRESERVING UPWIND FINITE VOLUME SCHEMES FOR MAGNETOHYDRODYNAMIC EQUATIONS
LOCALLY DIVERGENCE-PRESERVING UPWIND FINITE VOLUME SCHEMES FOR MAGNETOHYDRODYNAMIC EQUATIONS MANUEL. 11661191 Abstract. A main issue in nonstationary, compressible magnetohydrodynamic (MHD) simu- lations. Key words. magnetohydrodynamics, finite volume methods, divergence constraint, Nedelec elements AMS
Weak solutions to the equations of stationary magnetohydrodynamic flows in porous media
Sart, Remi
Weak solutions to the equations of stationary magnetohydrodynamic flows in porous media Youcef induction equation. Keywords: magnetohydrodynamic flows in porous media, Brinkman- Forchheimer equations Magnetohydrodynamic (MHD) flows in porous media arise in many appli- cations such as in chemical technology
IDEAL MAGNETOHYDRODYNAMIC STABILITY OF THE NCSX
Martín-Solís, José Ramón
IDEAL MAGNETOHYDRODYNAMIC STABILITY OF THE NCSX G. Y. FU,a * M. ISAEV,b L. P. KU,a M. MIKHAILOV,b M Received March 1, 2006 Accepted for Publication March 30, 2006 The ideal magnetohydrodynamic (MHD are signifi- cantly more stable than the local infinite-n modes. KEYWORDS: ideal magnetohydrodynamic stability
MAGNETOHYDRODYNAMICS MAGNETOHYDRODYNAMICS (or MHD for short) is
Priest, Eric
(F ) of a ux tube is the amount of magnetic ux crossing a section (S); i.e. F = Z s B #1; d itself, as well as the interstellar and intergalactic media and the stars and galaxies contained in themS: Consider a #12;nite segment of a ux tube bounded by plane sections S 1 and S 2 (Fig. 1). There is no ux
Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Cole, John; Lineberry, John; Chapman, Jim; Schmidt, Harold; Cook, Stephen (Technical Monitor)
2002-01-01
A fundamental obstacle to routine space access is the specific energy limitations associated with chemical fuels. In the case of vertical take-off, the high thrust needed for vertical liftoff and acceleration to orbit translates into power levels in the 10 GW range. Furthermore, useful payload mass fractions are possible only if the exhaust particle energy (i.e., exhaust velocity) is much greater than that available with traditional chemical propulsion. The electronic binding energy released by the best chemical reactions (e.g., LOX/LH2 for example, is less than 2 eV per product molecule (approx. 1.8 eV per H2O molecule), which translates into particle velocities less than 5 km/s. Useful payload fractions, however, will require exhaust velocities exceeding 15 km/s (i.e., particle energies greater than 20 eV). As an added challenge, the envisioned hypothetical RLV (reusable launch vehicle) should accomplish these amazing performance feats while providing relatively low acceleration levels to orbit (2-3g maximum). From such fundamental considerations, it is painfully obvious that planned and current RLV solutions based on chemical fuels alone represent only a temporary solution and can only result in minor gains, at best. What is truly needed is a revolutionary approach that will dramatically reduce the amount of fuel and size of the launch vehicle. This implies the need for new compact high-power energy sources as well as advanced accelerator technologies for increasing engine exhaust velocity. Electromagnetic acceleration techniques are of immense interest since they can be used to circumvent the thermal limits associated with conventional propulsion systems. This paper describes the Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) being undertaken at NASA Marshall Space Flight Center (MSFC). In this experiment, a 1-MW arc heater is being used as a feeder for a 1-MW magnetohydrodynamic (MHD) accelerator. The purpose of the experiment is to demonstrate that an MHD accelerator can be an effective augmentation system for increasing engine exhaust velocity. More specifically, the experiment is intended to show that electromagnetic effects are effective at producing flow acceleration whereas electrothermal effects do not cause unacceptable heating of the working fluid. The MHD accelerator was designed as an externally diagonalized segmented Faraday channel, which will be inserted into an existing 2-tesla electromagnet. This allows the external power to be connected through two terminals thereby minimizing the complexity and cost associated with powering each segment independently. The design of the accelerator and other components in the flow path has been completed and fabrication activities are underway. This paper provides a full description of MAPX including performance analysis, design, and test plans, and current status.
L Kang; Y Inui; T Matsuo; M Ishikawa; J Umoto
2000-01-01
Performance analyses of a commercial scale closed-cycle MHD disk generator are performed. A large scale MHD generator, superconducting magnet, inversion system and synchronous generator are designed. The MHD generator is operated with ArCs plasma and connected to the ac power infinite bus through line-commutated inverters, while the synchronous generator is operated in parallel. The thermal input is 1000 MW, and
On the magnetohydrodynamic load and the magnetohydrodynamic metage
Chakraborty, Sagar [S. N. Bose National Centre for Basic Sciences, Saltlake, Kolkata 700098 (India); Guha, Partha [S. N. Bose National Centre for Basic Sciences, Saltlake, Kolkata 700098 (India); Max Planck Institute for Mathematics in the Sciences, Inselstrasse 22, D-04103 Leipzig (Germany)
2008-01-15
In analogy with the load and the metage in hydrodynamics, this paper defines magnetohydrodynamic load and magnetohydrodynamic metage in the case of magnetofluids. They can be used to write the magnetic field in MHD in Clebsch's form. It has been shown herein how these two concepts can be utilized to derive the magnetic analog of the Ertel's theorem and also, how in the presence of nontrivial topology of the magnetic field in the magnetofluid one may associate the linking number of the magnetic field lines with the invariant MHD loads. The paper illustrates that the symmetry translation of the MHD metage in the corresponding label space generates the conservation of cross helicity.
MHD POWER EXTRACTION FROM COLD HYPERSONIC AIR FLOWS WITH EXTERNAL IONIZERS
Miles, Richard
below), engine inlet flow parameters could be tailored to optimize engine performance in off- design1 MHD POWER EXTRACTION FROM COLD HYPERSONIC AIR FLOWS WITH EXTERNAL IONIZERS Sergey O. Macheret, Princeton University D-414 Engineering Quadrangle, Princeton, NJ 08544 Abstract The paper analyzes a novel
Off-design study of an open cycle MHD power plant with oxygen enrichment
Geyer, H.K.; Berry, G.F.
1981-01-01
This paper undertakes to explore some of the more important aspects of off-design operation for an MHD power plant. An essential requirement is that the plant be designed to meet part-load and overload conditions. Furthermore, the optimal design should be subject to a specified load demand curve. For off-design regimes, an analysis is made to determine the compatible joint operating conditions for an MHD topping cycle, a steam bottoming plant, a turbine train, a compressor, and an oxygen separation plant. The analysis performed is subject to constraints (e.g. metal temperatures, second law violations, component performance requirements, environmental considerations).
An AC magnetohydrodynamic micropump
Asuncion V Lemoff; Abraham P Lee
2000-01-01
A microfluidic pump is presented using an AC magnetohydrodynamic (MHD) propulsion system in which the Lorentz force is used to propel an electrolytic solution along a microchannel etched in silicon. This micropump has no moving parts, produces a continuous (not pulsatile) flow and is compatible with solutions containing biological specimens. Theory, fabrication method and experimental results are described.
Results from study of potential early commercial MHD power plants and from recent ETF design work
F. Hals; R. Kessler; D. Swallom; L. Westra; J. Zar; W. Morgan; C. Bozzuto
1980-01-01
The study deals with different 'moderate technology' entry-level commercial MHD power plants. Two of the reference plants are based on combustion of coal with air preheated in a high-temperature regenerative air heater separately fired with a low-BTU gas produced in a gasifier integrated with the power plant. The third reference plant design is based on the use of oxygen enriched
Turbulent Magnetohydrodynamic Jet Collimation and Thermal Driving
Peter T. Williams
2003-12-21
We have argued that magnetohydrodynamic (MHD) turbulence in an accretion disk naturally produces hoop-stresses, and that in a geometrically-thick flow these stresses could both drive and collimate an outflow. We based this argument on an analogy of turbulent MHD fluids to viscoelastic fluids, in which azimuthal shear flow creates hoop-stresses that cause a variety of flow phenomena, including the Weissenberg effect in which a fluid climbs a spinning rod. One of the more important differences between the Weissenberg effect and astrophysical jets is the source of power. In our previous analysis, we only considered the power due to the spin-down torque on the central object, and thus found that we could only drive an outflow if the central object were maximally rotating. Here we take into account the energy that is liberated by the accreting matter, and describe a scenario in which this energy couples to the outflow to create a thermodynamic engine.
Performance calculations for 200-1000 MWe MHD/steam power plants
NASA Technical Reports Server (NTRS)
Staiger, P. J.
1981-01-01
The effects of MHD generator length, level of oxygen enrichment, and oxygen production power on the performance of MHD/steam power plants ranging from 200 to 1000 MW in electrical output are investigated. The plants considered use oxygen enriched combustion air preheated to 1100 F. Both plants in which the MHD generator is cooled with low temperature and pressure boiler feedwater and plants in which the generator is cooled with high temperature and pressure boiler feedwater are considered. For plants using low temperature boiler feedwater for generator cooling the maximum thermodynamic efficiency is obtained with shorter generators and a lower level of oxygen enrichment compared to plants using high temperature boiler feedwater for generator cooling. The generator length at which the maximum plant efficiency occurs increases with power plant size for plants with a generator cooled by low temperature feedwater. Also shown is the relationship of the magnet stored energy requirement of the generator length and the power plant performance. Possible cost/performance tradeoffs between magnet cost and plant performance are indicated.
Optimization of the oxidant supply system for combined cycle MHD power plants
NASA Technical Reports Server (NTRS)
Juhasz, A. J.
1982-01-01
An in-depth study was conducted to determine what, if any, improvements could be made on the oxidant supply system for combined cycle MHD power plants which could be reflected in higher thermal efficiency and a reduction in the cost of electricity, COE. A systematic analysis of air separation process varitions which showed that the specific energy consumption could be minimized when the product stream oxygen concentration is about 70 mole percent was conducted. The use of advanced air compressors, having variable speed and guide vane position control, results in additional power savings. The study also led to the conceptual design of a new air separation process, sized for a 500 MW sub e MHD plant, referred to a internal compression is discussed. In addition to its lower overall energy consumption, potential capital cost savings were identified for air separation plants using this process when constructed in a single large air separation train rather than multiple parallel trains, typical of conventional practice.
Advanced fusion MHD power conversion using the CFAR (compact fusion advanced Rankine) cycle concept
M. A. Hoffman; R. Campbell; B. G. Logan
1988-01-01
The CFAR (compact fusion advanced Rankine) cycle concept for a tokamak reactor involves the use of a high-temperature Rankine cycle in combination with microwave superheaters and nonequilibrium MHD disk generators to obtain a compact, low-capital-cost power conversion system which fits almost entirely within the reactor vault. The significant savings in the balance-of-plant costs are expected to result in much lower
Results from conceptual design study of potential early commercial MHD/steam power plants
NASA Technical Reports Server (NTRS)
Hals, F.; Kessler, R.; Swallom, D.; Westra, L.; Zar, J.; Morgan, W.; Bozzuto, C.
1981-01-01
This paper presents conceptual design information for a potential early MHD power plant developed in the second phase of a joint study of such plants. Conceptual designs of plant components and equipment with performance, operational characteristics and costs are reported on. Plant economics and overall performance including full and part load operation are reviewed. Environmental aspects and the methods incorporated in plant design for emission control of sulfur and nitrogen oxides are reviewed. Results from reliability/availability analysis conducted are also included.
Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Hypersonic Airbreathing Engines
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Cole, J. W.; Bityurin, V. A.; Lineberry, J. T.
2000-01-01
The prospects for realizing a magnetohydrodynamic (MHD) bypass hypersonic airbreathing engine are examined from the standpoint of fundamental thermodynamic feasibility. The MHD-bypass engine, first proposed as part of the Russian AJAX vehicle concept, is based on the idea of redistributing energy between various stages of the propulsion system flow train. The system uses an MHD generator to extract a portion of the aerodynamic heating energy from the inlet and an MHD accelerator to reintroduce this power as kinetic energy in the exhaust stream. In this way, the combustor entrance Mach number can be limited to a specified value even as the flight Mach number increases. Thus, the fuel and air can be efficiently mixed and burned within a practical combustor length, and the flight Mach number operating envelope can be extended. In this paper, we quantitatively assess the performance potential and scientific feasibility of MHD-bypass engines using a simplified thermodynamic analysis. This cycle analysis, based on a thermally and calorically perfect gas, incorporates a coupled MHD generator-accelerator system and accounts for aerodynamic losses and thermodynamic process efficiencies in the various engin components. It is found that the flight Mach number range can be significantly extended; however, overall performance is hampered by non-isentropic losses in the MHD devices.
Fault analysis of mid-channel power takeoff in DCW MHD generators
Ishikawa, M.; Wu, Y.C.L.; Scott, M.H.
1982-01-01
Analysis is presented of the effect of loading faults on the mid-channel power takeoff of a diagonal-conducting-wall MHD generator in special loading schemes. Two-dimensional calculations indicate that an open-circuit condition in the upstream load circuit results in a large current density at the power takeoff anode and drives a shorting current over the interframe insulators at the cathode side. A short-circuit condition in the upstream load circuit results in a large current density at the power takeoff cathode and a shorting current over the interframe insulators at the anode side.
The infinite interface limit of multiple-region relaxed magnetohydrodynamics
Dennis, G. R.; Dewar, R. L.; Hole, M. J. [Research School of Physics and Engineering, Australian National University, ACT 0200 (Australia); Hudson, S. R. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)
2013-03-15
We show the stepped-pressure equilibria that are obtained from a generalization of Taylor relaxation known as multi-region, relaxed magnetohydrodynamics (MRXMHD) are also generalizations of ideal magnetohydrodynamics (ideal MHD). We show this by proving that as the number of plasma regions becomes infinite, MRXMHD reduces to ideal MHD. Numerical convergence studies illustrating this limit are presented.
Methods of reducing energy consumption of the oxidant supply system for MHD/steam power plants
NASA Technical Reports Server (NTRS)
Juhasz, A. J.
1983-01-01
An in-depth study was conducted to identify possible improvements to the oxidant supply system for combined cycle MHD power plants which would lead to higher thermal efficiency and reduction in the cost of electricity, COE. Results showed that the oxidant system energy consumption could be minimized when the process was designed to deliver a product O2 concentration of 70 mole percent. The study also led to the development of a new air separation process, referred to as liquid pumping and internal compression. MHD system performance calculations show that the new process would permit an increase in plant thermal efficiency of 0.6 percent while allowing more favorable tradeoffs between magnetic energy and oxidant system capacity requirements.
Methods of reducing energy consumption of the oxidant supply system for MHD/steam power plants
NASA Technical Reports Server (NTRS)
Juhasz, A. J.
1983-01-01
An in-depth study was conducted to identify possible improvements to the oxidant supply system for combined cycle MHD power plants which would lead to higher thermal efficiency and reduction in the cost of electricity, COE. Results showed that the oxidant system energy consumption could be minimized when the process was designed to deliver a product O2 concentration of 70 mole percent. The study also led to the development of a new air separation process, referred to as 'liquid pumping and internal compression'. MHD system performance calculations show that the new process would permit an increase in plant thermal efficiency of 0.6 percent while allowing more favorable tradeoffs between magnetic energy and oxidant system capacity requirements.
Nonlocality and the critical Reynolds numbers of the minimum state magnetohydrodynamic turbulence
Oughton, Sean
Nonlocality and the critical Reynolds numbers of the minimum state magnetohydrodynamic turbulence 2011; accepted 24 May 2011; published online 21 July 2011) Magnetohydrodynamic (MHD) systems can.1063/1.3606473] I. INTRODUCTION Magnetohydrodynamic (MHD) turbulence1,2 has been widely employed as a physical model
Study of small-amplitude magnetohydrodynamic surface waves on liquid Hantao Ji,a)
Ji, Hantao
Study of small-amplitude magnetohydrodynamic surface waves on liquid metal Hantao Ji,a) William Fox 2004; accepted 28 September 2004; published online 23 November 2004) Magnetohydrodynamic (MHD) surface is to understand the physics of magnetohydrodynamic (MHD) surface waves7 in a static pool subject to an externally
Reduced Models of Magnetohydrodynamic Turbulence in the Interstellar Medium and the
Ng, Chung-Sang
Reduced Models of Magnetohydrodynamic Turbulence in the Interstellar Medium and the Solar Wind A magnetohydrodynamic (MHD) turbulence are discussed. A four-field system of equations has been derived from the compressible magnetohydrodynamic (MHD) equations to describe turbulence in the interstellar medium
Wright, Andrew N.
Properties of Hall magnetohydrodynamic waves modified by electron inertia and finite Larmor radius dispersion relation is derived for Hall magnetohydrodynamic MHD waves including electron inertial and finite of magnetohydrodynamic MHD waves has been well established. Recently, Ref. 1 provided a very lucid summary and analysis
Nonlocality and the Critical Reynolds Numbers of the Minimum State Magnetohydrodynamic Turbulence Magnetohydrodynamic (MHD) systems can be strongly nonlinear (turbulent) when their kinetic and magnetic Reynolds Magnetohydrodynamic (MHD) turbulence [1, 2] has been widely employed as a physical model in simulations and mod- eling
Scaling of forced magnetic reconnection in the Hall-magnetohydrodynamic Taylor problem
Fitzpatrick, Richard
Scaling of forced magnetic reconnection in the Hall-magnetohydrodynamic Taylor problem Richard-dimensional, incompressible, zero guide-field, nonlinear Hall-MHD magnetohydrodynamical simulations are used to investigate magnetohydrodynamical MHD theory is capable of accounting for magnetic reconnection, but generally predicts reconnection
California at Berkeley, University of
A COMPARISON BETWEEN GLOBAL SOLAR MAGNETOHYDRODYNAMIC AND POTENTIAL FIELD SOURCE SURFACE MODEL used: (1) potential field source surface (PFSS) models, and (2) the magnetohydrodynamic (MHD) models of the solar corona are (1) potential field source surface (PFSS) models, and (2) magnetohydrodynamic (MHD
Structure of homogeneous nonhelical magnetohydrodynamic turbulence R. S. Miller,a)
Miller, Richard S.
Structure of homogeneous nonhelical magnetohydrodynamic turbulence R. S. Miller,a) F. Mashayek, V for three-dimensional direct numerical simulations of nonhelical magnetohydrodynamic MHD turbulence for both of turbulence in electrically conducting fluids obeying the magnetohydrodynamic MHD equations.2 Non- linear
Computation of multi-region relaxed magnetohydrodynamic equilibria S. R. Hudson,1,a)
Hudson, Stuart
Computation of multi-region relaxed magnetohydrodynamic equilibria S. R. Hudson,1,a) R. L. Dewar,2 the construction of stepped-pressure equilibria as extrema of a multi-region, relaxed magnetohydrodynamic (MHD-fluid magnetohydrodynam- ics (MHD) is commonly used for modeling the global, long- time-scale state of plasmas
The third-order law for magnetohydrodynamic turbulence with shear: Numerical investigation
Oughton, Sean
The third-order law for magnetohydrodynamic turbulence with shear: Numerical investigation M. Wan,1 magnetohydrodynamic MHD turbulence relate the observable structure function with the energy dissipation rate. Recently cascade in incompressible hydrody- namics HD .3 The magnetohydrodynamic MHD analog of the 4/5 law
NASA Astrophysics Data System (ADS)
Riley, Pete; Linker, Jon A.; Lionello, R.; Mikic, Z.
2012-07-01
The declining phase of solar activity cycle 23 has provided an unprecedented opportunity to study the evolution and properties of corotating interaction regions (CIRs) during unique and relatively steady conditions. The absence of significant transient activity has allowed modelers to test ambient solar wind models, but has also challenged them to reproduce structure that was qualitatively different than had been observed previously (at least within the space era). In this study, we present and analyze global magnetohydrodynamic (MHD) solutions of the inner heliosphere (from 1RS to 1 AU) for several intervals defined as part of a Center for Integrated Space weather Modeling (CISM) interdisciplinary campaign study, and, in particular, Carrington rotation 2060. We compare in situ measurements from ACE and STEREO A and B with the model results to illustrate both the capabilities and limitations of current numerical techniques. We show that, overall, the models do capture the essential structural features of the solar wind for specific time periods; however, there are times when the models and observations diverge. We describe, and, to some extent assess the sources of error in the modeling chain from the input photospheric magnetograms to the numerical schemes used to propagate structure through the heliosphere, and speculate on how they may be resolved, or at least mitigated in the future.
Wu, S. T.
1987-03-01
Theoretical and numerical modeling of solar activity and its effects on the solar atmosphere within the context of magnetohydrodynamics were examined. Specifically, the scientific objectives were concerned with the physical mechanisms for the flare energy build-up and subsequent release. In addition, transport of this energy to the corona and solar wind was also investigated. Well-posed, physically self-consistent, numerical simulation models that are based upon magnetohydrodynamics were sought. A systematic investigation of the basic processes that determine the macroscopic dynamic behavior of solar and heliospheric phenomena was conducted. A total of twenty-three articles were accepted and published in major journals. The major achievements are summarized.
Advanced LMMHD space power generation concept
NASA Astrophysics Data System (ADS)
Ho, Vincent; Wong, Albert; Kim, Kilyoo; Dhir, Vijay
Magnetohydrodynamic (MHD) power generation concept has been proposed and studied worldwide as one of the future power generation sources. An advanced one fluid two phase liquid metal (LM) MHD power generation concept was developed for space nuclear power generation design. The concept employs a nozzle to accelerate the liquid metal coolant to an acceptable velocity with Mach number greater than unity. Such nozzle and the MHD power generator replace the turbogenerator of a high temperature Rankine turboelectric cycle concept. As a result, the power generation system contains no movable parts. This provides high reliability, which is a very important factor in space application.
Load flow studies in the presence of magnetohydrodynamic electromagnetic pulse
Kruse, V.J.; Rackliffe, G.B.; Barnes, P.R.
1989-01-01
Seconds after an high-altitude nuclear event the earth's surface experiences a very low frequency, quasi-DC magnetohydrodynamic electromagnetic fields (MHD-EMP). MHD-EMP fields impress quasi-DC currents on transmission and sub-transmission lines. These current magnitudes can exceed several times the transformer exciting current levels. Transformers and shunt reactors experience severe halfcycle saturation resulting in harmonics and increased VAR demand. This paper reviews the calculation of the quasi-DC currents, discusses the calculation of the increased VAR demand, and evaluates the effect of a simulated MHD-EMP event on a power system with stability and load flow analyses. 9 refs., 5 figs., 3 tabs.
Phase mixing of a three dimensional magnetohydrodynamic pulse
D. Tsiklauri; V. M. Nakariakov; G. Rowlands
2003-03-12
Phase mixing of a three dimensional magnetohydrodynamic (MHD) pulse is studied in the compressive, three-dimensional (without an ignorable coordinate) regime. It is shown that the efficiency of decay of an Alfvenic part of a compressible MHD pulse is related linearly to the degree of non-planeness of the pulse in the homogeneous transverse direction. In the developed stage of phase mixing (for large times), coupling to its compressive part does not alter the power-law decay of an Alfvenic part of a compressible MHD pulse. The same applies to the dependence upon the resistivity of the Alfvenic part of the pulse. All this implies that the dynamics of Alfven waves can still be qualitatively understood in terms of the previous 2.5D models. Thus, the phase mixing remains a relevant paradigm for the coronal heating applications in the realistic 3D geometry and compressive plasma.
R. L. Dewar; R. Mills; M. J. Hole
2008-10-14
The celebration of Allan Kaufman's 80th birthday was an occasion to reflect on a career that has stimulated the mutual exchange of ideas (or memes in the terminology of Richard Dawkins) between many researchers. This paper will revisit a meme Allan encountered in his early career in magnetohydrodynamics, the continuation of a magnetohydrodynamic mode through a singularity, and will also mention other problems where Allan's work has had a powerful cross-fertilizing effect in plasma physics and other areas of physics and mathematics.
Dewar, R L; Hole, M J
2008-01-01
The celebration of Allan Kaufman's 80th birthday was an occasion to reflect on a career that has stimulated the mutual exchange of ideas (or memes in the terminology of Richard Dawkins) between many researchers. This paper will revisit a meme Allan encountered in his early career in magnetohydrodynamics, the continuation of a magnetohydrodynamic mode through a singularity, and will also mention other problems where Allan's work has had a powerful cross-fertilizing effect in plasma physics and other areas of physics and mathematics.
Magnetohydrodynamics and Plasma Cosmology
K. Kleidis; A. Kuiroukidis; D. B. Papadopoulos; L. Vlahos
2005-12-22
We study the linear magnetohydrodynamic (MHD) equations, both in the Newtonian and the general-relativistic limit, as regards a viscous magnetized fluid of finite conductivity and discuss instability criteria. In addition, we explore the excitation of cosmological perturbations in anisotropic spacetimes, in the presence of an ambient magnetic field. Acoustic, electromagnetic (e/m) and fast-magnetosonic modes, propagating normal to the magnetic field, can be excited, resulting in several implications of cosmological significance.
On spectral scaling laws for incompressible anisotropic magnetohydrodynamic turbulence
Pouquet, Annick
1 On spectral scaling laws for incompressible anisotropic magnetohydrodynamic turbulence S, France (Dated: August 16, 2005) Abstract A heuristic model is given for anisotropic magnetohydrodynamics. The magnetohydrodynamics (MHD) approximation has proved to be quite successful in the study of a variety of space plasmas
Gravitational radiation from primordial helical magnetohydrodynamic turbulence.
Kahniashvili, Tina; Gogoberidze, Grigol; Ratra, Bharat
2008-06-13
We consider gravitational waves (GWs) generated by primordial inverse-cascade helical magneto-hydrodynamical (MHD) turbulence produced by bubble collisions at the electroweak phase transitions (EWPT). Compared to the unmagnetized EWPT case, the spectrum of MHD-turbulence-generated GWs peaks at lower frequency with larger amplitude and can be detected by the proposed Laser Interferometer Space Antenna. PMID:18643481
Multi-region relaxed magnetohydrodynamics with flow
Dennis, G. R., E-mail: graham.dennis@anu.edu.au; Dewar, R. L.; Hole, M. J. [Research School of Physics and Engineering, Australian National University, ACT 0200 (Australia)] [Research School of Physics and Engineering, Australian National University, ACT 0200 (Australia); Hudson, S. R. [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States)
2014-04-15
We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes plasma flow. This new model is a generalization of Woltjer's model of relaxed magnetohydrodynamics equilibria with flow. We prove that as the number of plasma regions becomes infinite, our extension of MRxMHD reduces to ideal MHD with flow. We also prove that some solutions to MRxMHD with flow are not time-independent in the laboratory frame, and instead have 3D structure which rotates in the toroidal direction with fixed angular velocity. This capability gives MRxMHD potential application to describing rotating 3D MHD structures such as 'snakes' and long-lived modes.
Computational fusion magnetohydrodynamics
Grimm, R.C.
1984-01-01
Simple magnetohydrodynamic models provide the framework for much of our understanding of the macroscopic behavior of magnetically confined laboratory plasmas. In even the simplest of models, however, the many different time and spatial scales, the multidimensionality, and the nonlinearity of the equations make finding solutions difficult. In realistic geometries obtaining quantitative results to aid our understanding, to interpret experiment, and to design new devices, involves the development of large scale numerical codes. During the past decade considerable effort has been extended in the fusion community to develop equilibrium, linear stability, and nonlinear time evolution codes in two and three dimensions, some of which have had a considerable impact on the fusion program. An overview of the various types of codes and numerical methods is given. Emphasis is on the spectrum of linear perturbations and ideal MHD stability, boundary layer methods and resistive MHD stability, and modeling of nonlinear, time evolution resistive MHD phenomena in tokamak configurations.
Magneto-Hydrodynamics Based Microfluidics
Qian, Shizhi; Bau, Haim H.
2009-01-01
In microfluidic devices, it is necessary to propel samples and reagents from one part of the device to another, stir fluids, and detect the presence of chemical and biological targets. Given the small size of these devices, the above tasks are far from trivial. Magnetohydrodynamics (MHD) offers an elegant means to control fluid flow in microdevices without a need for mechanical components. In this paper, we review the theory of MHD for low conductivity fluids and describe various applications of MHD such as fluid pumping, flow control in fluidic networks, fluid stirring and mixing, circular liquid chromatography, thermal reactors, and microcoolers. PMID:20046890
Hamiltonian formalism of extended magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Abdelhamid, H. M.; Kawazura, Y.; Yoshida, Z.
2015-06-01
The extended magnetohydrodynamics (MHD) system, including the Hall effect and the electron inertia effect, has a Hamiltonian structure embodied by a noncanonical Poisson algebra on an infinite-dimensional phase space. A nontrivial part of the formulation is the proof of Jacobi?s identity for the Poisson bracket. We unearth a basic Lie algebra that generates the Poisson bracket. A class of similar Poisson algebra may be generated by the same Lie algebra, which encompasses the Hall MHD system and inertial MHD system.
A Simple Finite Difference Scheme for Multidimensional Magnetohydrodynamical Equations
Wenlong Dai; Paul R. Woodward
1998-01-01
An approximate MHD Riemann solver, an approach to maintain the divergence-free condition of magnetic field, and a finite difference scheme for multidimensional magnetohydrodynamical (MHD) equations are proposed in this paper. The approximate MHD Riemann solver is based on characteristic formulations. Both the conservation laws for mass, momentum, energy, and magnetic field, and the divergence-free condition of the magnetic field are
M. Palmroth; P. Janhunen; G. Germany; D. Lummerzheim; K. Liou; D. N. Baker; C. Barth; A. T. Weatherwax; J. Watermann
2006-01-01
We compare the ionospheric electron precipitation morphology and power from a global MHD simulation (GUMICS-4) with direct measurements of auroral energy flux during a pair of substorms on 28-29 March 1998. The electron precipitation power is computed directly from global images of auroral light observed by the Polar satellite ultraviolet imager (UVI). Independent of the Polar UVI measurements, the electron
Small-scale structures in three-dimensional magnetohydrodynamic turbulence P.D. Mininni1
Pouquet, Annick
Small-scale structures in three-dimensional magnetohydrodynamic turbulence P.D. Mininni1 , A, extreme events in magnetohydrodynamics (MHD) being observed to be more intense than in neutral flu- ids; e
Global Mhd Simulations: Comparisons With Cluster Observations
NASA Astrophysics Data System (ADS)
Berchem, J.
Three-dimensional magnetohydrodynamic (MHD) simulation has become a power tool to investigate the global interaction of the solar wind with the Earth magne- tosphere and to link multispacecraft measurements. Although Cluster's multi-point measurements provide most of the time information on a finer scale than that resolv- able by MHD models, global simulations can be used to establish causal relationships between local measurements and the large-scale dynamics of the magnetosphere. We present the results of several studies based on recent Cluster passes through the day- side magnetopause and the cusp. These case studies use magnetic field and plasma parameters measured upstream of the bow shock as input to the simulations and in- clude both typical and extreme solar wind conditions. We demonstrate how comparing local data streams and ionospheric activity deduced from the simulations with Cluster measurements provides information that can be used to reconstruct the global topol- ogy and dynamics of the dayside magnetosphere extant during the events.
Preliminary results in the NASA Lewis H2-O2 combustion MHD experiment
NASA Technical Reports Server (NTRS)
Smith, J. M.
1979-01-01
MHD (magnetohydrodynamic) power generation experiments were carried out in the NASA Lewis Research Center cesium-seeded H2-O2 combustion facility. This facility uses a neon-cooled cryomagnet capable of producing magnetic fields in excess of 5 tesla. The effects of power takeoff location, generator loading, B-field strength, and electrode breakdown on generator performance are discussed. The experimental data is compared to a theory based on one-dimensional flow with heat transfer, friction, and voltage drops.
Criteria for Scaled Laboratory Simulations of Astrophysical MHD Phenomena
Ryutov, D. D.; Drake, R. P.; Remington, B. A.
2000-04-01
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.
Diagnostic development and support of MHD test facilities
Not Available
1990-01-01
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at 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 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. 9 figs., 1 tab.
Parabolized Navier-Stokes Code for Computing Magneto-Hydrodynamic Flowfields
NASA Technical Reports Server (NTRS)
Mehta, Unmeel B. (Technical Monitor); Tannehill, J. C.
2003-01-01
This report consists of two published papers, 'Computation of Magnetohydrodynamic Flows Using an Iterative PNS Algorithm' and 'Numerical Simulation of Turbulent MHD Flows Using an Iterative PNS Algorithm'.
Turner, A J; Chapman, S C
2011-01-01
Single point spacecraft observations of the turbulent solar wind flow exhibit a characteristic nonaxisymmetric anisotropy that depends sensitively on the perpendicular power spectral exponent. For the first time we use this nonaxisymmetric anisotropy as a function of wave vector direction to test models of magnetohydrodynamic (MHD) turbulence. Using Ulysses magnetic field observations in the fast, quiet polar solar wind we find that the Goldreich-Sridhar model of MHD turbulence is not consistent with the observed anisotropy, whereas the observations are well reproduced by the "Slab + 2D" model. The Golderich-Sridhar model alone can not account for the observations unless an additional component is also present.
Solar flares and focused energy transport by MHD waves
NASA Astrophysics Data System (ADS)
Russell, A. J. B.; Stackhouse, D. J.
2013-10-01
Context. Transport of flare energy from the corona to the chromosphere has traditionally been assigned to electron beams; however, interest has recently been renewed in magnetohydrodynamic (MHD) waves as a complementary or alternative mechanism. Aims: We determine whether, and under what conditions, MHD waves deliver spatially localised energy to the chromosphere, as required if MHD waves are to contribute to emission from flare ribbons and kernels. This paper also highlights several properties of MHD waves that are relevant to solar flares and demonstrates their application to the flare problem. Methods: Transport is investigated using a magnetic arcade model and 2.5D MHD simulations. Different wave polarisations are considered and the effect of fine structuring transverse to the magnetic field is also examined. Ray tracing provides additional insight into the evolution of waveguided fast waves. Results: Alfvén waves are very effective at delivering energy fluxes to small areas of chromosphere, localisation being enhanced by magnetic field convergence and phase mixing. Fast waves, in the absence of fine coronal structure, are more suited to powering emission from diffuse rather than compact sources; however, fast waves can be strongly localised by coronal waveguides, in which case focused energy is best transported to the chromosphere when waveguides are directly excited by the energy release. Conclusions: MHD waves pass an important test for inclusion in future flare models.
Criteria For MHD Sea Mater Propulsion
J. T. Lineberry; Y. C. L. Susan Wu
1990-01-01
A general overview of current technology issues that are related to the application of magnetohydrodynamic propulsion to ocean vessels is given. These discussions are directed at Naval applications. The sea water MHD process is reviewed. Key parameters which influence the thruster effectiveness and its operation are discussed. These parameters are viewed in perspective with MHD thruster design features and its
Improvement of Scramjet Performance-Experimental Demonstration of MHD Acceleration
NASA Technical Reports Server (NTRS)
Bogdanoff, David W.; Park, Chul; Mehta, Unmeel B.; Arnold, James (Technical Monitor)
2001-01-01
One of the critical technologies of MHD (Magnetohydrodynamics) bypass scramjet propulsion for space launch and cruise vehicles is MHD acceleration. An experiment in a shock tunnel is described in which MHD acceleration is investigated experimentally. The objectives, the methods used and the preliminary results are described in this paper.
Temporal intermittency of energy dissipation in magnetohydrodynamic turbulence.
Zhdankin, Vladimir; Uzdensky, Dmitri A; Boldyrev, Stanislav
2015-02-13
Energy dissipation in magnetohydrodynamic (MHD) turbulence is known to be highly intermittent in space, being concentrated in sheetlike coherent structures. Much less is known about intermittency in time, another fundamental aspect of turbulence which has great importance for observations of solar flares and other space or astrophysical phenomena. In this Letter, we investigate the temporal intermittency of energy dissipation in numerical simulations of MHD turbulence. We consider four-dimensional spatiotemporal structures, "flare events," responsible for a large fraction of the energy dissipation. We find that although the flare events are often highly complex, they exhibit robust power-law distributions and scaling relations. We find that the probability distribution of dissipated energy has a power-law index close to ??1.75, similar to observations of solar flares, indicating that intense dissipative events dominate the heating of the system. We also discuss the temporal asymmetry of flare events as a signature of the turbulent cascade. PMID:25723225
On Hall magnetohydrodynamics equilibria
Throumoulopoulos, G. N.; Tasso, H. [University of Ioannina, Association Euratom - Hellenic Republic, Section of Theoretical Physics, GR 451 10 Ioannina (Greece); Max-Planck-Institut fuer Plasmaphysik, Euratom Association, D-85748 Garching (Germany)
2006-10-15
Steady states are studied in the framework of the ideal Hall magnetohydrodynamics (HMHD) model in arbitrary and axisymmetric geometries. In arbitrary geometry, conditions are found under which certain magnetohydrodynamics (MHD) equilibrium solutions can also satisfy the HMHD equations. For axisymmetric plasmas reduced equations are derived for uniform electron temperatures on magnetic surfaces and either barotropic ions or incompressible ion flows. The Hall and electron pressure gradient terms result in a deviation of the magnetic from the ion velocity surfaces, and consequently, the axisymmetric equilibria obey a set of coupled partial differential equations: one for the poloidal magnetic flux function and the other for a flux function labeling the ion velocity surfaces. Furthermore, the characteristics of certain classes of axisymmetric steady states with side conditions, as flows parallel to the magnetic field or purely poloidal incompressible flows, are identified and compared with respective MHD equilibria. Unlike in the frame of MHD, steady states with parallel axisymetric flows must be incompressible and equilibria with purely poloidal incompressible flows are possible. Certain analytic axisymmetric solutions are also constructed.
Ideal MHD stability of a spherical tokamak power plant and a component test facility.
Hole, M. J.; Wilson, H. R.; Abeysuriya, R.; Larson, J. W. (CLS-CI); ( MCS); (Australian National Univ.); (Univ. of York); (Univ. of Sydney)
2010-12-01
We have investigated ideal MHD stability of two advanced spherical tokamak confinement concepts: the spherical tokamak power plant (STPP), a 3 GW concept fusion power plasma producing 1 GW of electric power, and the component test facility (CTF), a concept designed for in situ materials testing for ITER and beyond. Detailed stability studies for toroidal mode number n = 1, 2, 3 displacements are presented as a function of conformal wall radius R{sub w} and on-axis safety factor q{sub 0}. For the STPP marginal stability scans held the current profile fixed, but varied the total plasma current. For the CTF we have extended and parallelized earlier marginal stability scans to scan over both the plasma beta and q{sub 0} by varying the current profile to preserve the total plasma current. These confirm that both concepts are stable provided that the wall is sufficiently close and q{sub 0} sufficiently large (q{sub 0} > 2.8 for the power plant and q{sub 0} > 2.1 for the CTF). Both power plant and CTF configurations are found to be ballooning stable.
Use of MHD systems in hypersonic aircraft
V. L. Fraishtadt; A. L. Kuranov; E. G. Sheikin
1998-01-01
The possibilities of using magnetohydrodynamic (MHD) systems on hypersonic aircraft are discussed. The distinctive features\\u000a of using MHD systems in the flow path of ramjet engines are examined. A quasi-one-dimensional mathematical model for the engine\\u000a is presented which includes the MHD interaction with the flow. It is shown that the specific impulse of an engine system can\\u000a be raised by
Plasma relaxation and topological aspects in Hall magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Shivamoggi, Bhimsen
2013-10-01
Parker's formulation of isotopological plasma relaxation process in magnetohydrodynamics (MHD) is extended to Hall MHD (Shivamoggi). The torsion coefficient al in the Hall MHD Beltrami condition turns out now to be proportional to the potential vorticity. The Hall MHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics if the Hall MHD Lagrange multiplier ? is taken to be proportional to the potential vorticity as well. The winding pattern of the magnetic field lines in Hall MHD then appears to evolve in the same way as potential vorticity lines in 2D hydrodynamics.
Plasma relaxation and topological aspects in Hall magnetohydrodynamics
Shivamoggi, B. K. [University of Central Florida, Orlando, Florida 32816-1364 (United States)
2012-07-15
Parker's formulation of isotopological plasma relaxation process in magnetohydrodynamics (MHD) is extended to Hall MHD. The torsion coefficient {alpha} in the Hall MHD Beltrami condition turns out now to be proportional to the potential vorticity. The Hall MHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics if the Hall MHD Lagrange multiplier {beta} is taken to be proportional to the potential vorticity as well. The winding pattern of the magnetic field lines in Hall MHD then appears to evolve in the same way as potential vorticity lines in 2D hydrodynamics.
Cesium-seeded hydrogen-magnetohydrodynamic disk generator
Jackson, W.D. [HMJ Corp., Kensington, MD (United States); Seikel, G.R. [SeiTec, Inc., Cleveland, OH (United States)
1996-12-31
A magnetohydrodynamic generator (MHD) of the disk type operated on cesium-seeded hydrogen yields a high performance system of low overall specific mass and is especially attractive for nuclear electric space power systems. Realization of a system of this type depends critically on the achievement of stable, nonequilibrium ionization in hydrogen. This paper presents an analytical method which establishes the stable nonequilibrium conductivity in terms of the temperature coefficient of electrical conductivity. The paper concludes with the determination of the experimental conditions under which the required stable regime can be demonstrated.
École Normale Supérieure
-dimensional homogeneous magnetohydrodynamic turbulence Katsunori Yoshimatsu,1,a Yuji Kondo,1 Kai Schneider,2,b Naoya-dimensional homogeneous magnetohydrodynamic MHD turbulence is proposed, which is based on the orthogonal wavelet
Magnetohydrodynamic Rebound Shocks of Supernovae
Yu-Qing Lou; Wei-Gang Wang
2007-04-02
We construct magnetohydrodynamic (MHD) similarity rebound shocks joining `quasi-static' asymptotic solutions around the central degenerate core to explore an MHD model for the evolution of random magnetic field in supernova explosions. This provides a theoretical basis for further studying synchrotron diagnostics, MHD shock acceleration of cosmic rays, and the nature of intense magnetic field in compact objects. The magnetic field strength in space approaches a limiting ratio, that is comparable to the ratio of the ejecta mass driven out versus the progenitor mass, during this self-similar rebound MHD shock evolution. The intense magnetic field of the remnant compact star as compared to that of the progenitor star is mainly attributed to both the gravitational core collapse and the radial distribution of magnetic field.
Magnetohydrodynamic Rebound Shocks of Supernovae
Lou, Yu-Qing
2007-01-01
We construct magnetohydrodynamic (MHD) similarity rebound shocks joining `quasi-static' asymptotic solutions around the central degenerate core to explore an MHD model for the evolution of random magnetic field in supernova explosions. This provides a theoretical basis for further studying synchrotron diagnostics, MHD shock acceleration of cosmic rays, and the nature of intense magnetic field in compact objects. The magnetic field strength in space approaches a limiting ratio, that is comparable to the ratio of the ejecta mass driven out versus the progenitor mass, during this self-similar rebound MHD shock evolution. The intense magnetic field of the remnant compact star as compared to that of the progenitor star is mainly attributed to both the gravitational core collapse and the radial distribution of magnetic field.
A bow shock flow containing (almost) all types of (`exotic') MHD discontinuities
De Sterck, Hans
A bow shock flow containing (almost) all types of (`exotic') MHD discontinuities H. De Sterck, H-aligned ideal Magnetohydrodynamic (MHD) bow shock flow in a regime where fast MHD switch-on shocks are possible to a compli- cated solution with interacting shocks of different MHD shock type. Fast and slow shocks
Not Available
1981-11-01
Program accomplishments in a continuing effort to demonstrate the feasibility of direct coal-fired, closed-cycle MHD power generation are reported. This volume contains the following appendices: (A) user's manual for 2-dimensional MHD generator code (2DEM); (B) performance estimates for a nominal 30 MW argon segmented heater; (C) the feedwater cooled Brayton cycle; (D) application of CCMHD in an industrial cogeneration environment; (E) preliminary design for shell and tube primary heat exchanger; and (F) plant efficiency as a function of output power for open and closed cycle MHD power plants. (WHK)
Nakamura, Masanori [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Garofalo, David; Meier, David L., E-mail: nakamura@stsci.ed, E-mail: david.a.garofalo@jpl.nasa.go, E-mail: david.l.meier@jpl.nasa.go [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2010-10-01
This is the first in a series of papers that introduces a new paradigm for understanding the jet in M87: a collimated relativistic flow in which strong magnetic fields play a dominant dynamical role. Here, we focus on the flow downstream of HST-1-an essentially stationary flaring feature that ejects trails of superluminal components. We propose that these components are quad relativistic magnetohydrodynamic shock fronts (forward/reverse fast and slow modes) in a narrow jet with a helically twisted magnetic structure. And we demonstrate the properties of such shocks with simple one-dimensional numerical simulations. Quasi-periodic ejections of similar component trails may be responsible for the M87 jet substructures observed further downstream on 10{sup 2}-10{sup 3} pc scales. This new paradigm requires the assimilation of some new concepts into the astrophysical jet community, particularly the behavior of slow/fast-mode waves/shocks and of current-driven helical kink instabilities. However, the prospects of these ideas applying to a large number of other jet systems may make this worth the effort.
Channel-wall limitations in the magnetohydrodynamic induction generator
NASA Technical Reports Server (NTRS)
Jackson, W. D.; Pierson, E. S.
1969-01-01
Discussion of magnetohydrodynamic induction generator examines the machine in detail and materials problems influencing its design. The higher upper-temperature limit of the MHD system promises to be more efficient than present turbine systems for generating electricity.
System study of an MHD\\/gas turbine combined-cycle baseload power plant
Annen
1982-01-01
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 consisted of an MHD plant with a gas turbine bottoming plant, and required no cooling water. The gas turbine plant uses only air as its working fluid and receives its energy input from
On the locality of magnetohydrodynamic turbulence scale fluxes
Teaca, Bogdan [Centre de Recherches en Physique des Plasmas, Science de Base, Ecole Polytechnique Federale de Lausanne, Station 13, Building PPB, CH-1015 Lausanne (Switzerland); Carati, Daniele [Statistical and Plasma Physics, Faculty of Sciences, Universite Libre de Bruxelles, Campus Plaine, CP 231, B-1050 Brussels (Belgium); Andrzej Domaradzki, J. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California 90089-1191 (United States)
2011-11-15
The scale locality of energy fluxes for magnetohydrodynamics (MHD) is investigated numerically for stationary states of turbulence. Two types of forces are used to drive turbulence, a kinetic force that acts only on the velocity field and a kinetic-inductive force, which acts on the velocity and magnetic fields alike. The analysis is performed in spectral space, which is decomposed into a series of shells following a power law for the boundaries. The triadic transfers occurring among these shells are computed, and the fluxes and locality functions are obtained by partial summation over the relevant shells. Employing Kraichnan locality functions, values of 1/3 and 2/3 for the scaling exponents of the four MHD energy fluxes are found. These values are smaller than the value of 4/3 found for hydrodynamic turbulence. To better understand these results, an in depth analysis is performed on the total energy flux.
NASA Astrophysics Data System (ADS)
Nakamura, Masanori; Garofalo, D. A.; Meier, D. L.
2010-01-01
We introduce a new paradigm for understanding the jet in M87: a collimated relativistic flow in which strong magnetic fields play a dominant dynamical role. Here we focus on the flow downstream of HST-1 - an essentially stationary flaring feature that ejects trails of superluminal components. We propose that these components are quad relativistic MHD shock fronts (forward fast/slow and reverse slow/fast modes) in a narrow jet with a helically twisted magnetic structure. And we demonstrate the properties of such shocks with simple one-dimensional numerical simulations. Quasi-periodic ejections of similar component trails may be responsible for the M87 jet substructures observed further downstream on kpc scales. This new paradigm requires the assimilation of some new concepts into the astrophysical jet community, particularly the behavior of slow/fast-mode waves/shocks and of current-driven helical kink instabilities. However, the prospects of these ideas applying to a large number of other jet systems may make this worth the effort. M.N. greatly acknowledges support from the Allan C. Davis fellowship jointly awarded by the Department of Physics and Astronomy at Johns Hopkins University and the Space Telescope Science Institute. Part of this research described was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.
Method for manufacturing magnetohydrodynamic electrodes
Killpatrick, D.H.; Thresh, H.R.
1980-06-24
A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator is described comprising the steps of preparing a billet having a core of a first metal, a tubular sleeve of a second metal, and an outer sheath of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MHD channel frame. The method forms a bond between the first metal of the core and the second metal of the sleeve strong enough to withstand a hot and corrosive environment.
An AC magnetohydrodynamic micropump: towards a true integrated microfluidic system
Lee, A P; Lemoff, A V; McConaghy, C F; Miles, R R
1999-03-01
An AC Magnetohydrodynamic (MHD) micropump has been demonstrated in which the Lorentz force is used to propel an electrolytic solution along a microchannel etched in silicon. This micropump has no moving parts, produces a continuous (not pulsatile) flow, and is compatible with solutions containing biological specimens. micropump, using the Lorentz force as the pumping mechanism for biological analysis. The AC Magnetohydrodynamic (MHD) micropump investigated produces a continuous flow and allows for complex microchannel design.
Lattice Boltzmann model for simulation of magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Chen, Shiyi; Chen, Hudong; Martinez, Daniel; Matthaeus, William
1991-01-01
A numerical method, based on a discrete Boltzmann equation, is presented for solving the equations of magnetohydrodynamics (MHD). The algorithm provides advantages similar to the cellular automaton method in that it is local and easily adapted to parallel computing environments. Because of much lower noise levels and less stringent requirements on lattice size, the method appears to be more competitive with traditional solution methods. Examples show that the model accurately reproduces both linear and nonlinear MHD phenomena.
NASA Technical Reports Server (NTRS)
Hals, F.; Kessler, R.; Swallom, D.; Westra, L.; Zar, J.; Morgan, W.; Bozzuto, C.
1980-01-01
The study deals with different 'moderate technology' entry-level commercial MHD power plants. Two of the reference plants are based on combustion of coal with air preheated in a high-temperature regenerative air heater separately fired with a low-BTU gas produced in a gasifier integrated with the power plant. The third reference plant design is based on the use of oxygen enriched combustion air. Performance calculations show that an overall power plant efficiency of the order of 44% can be reached with the use of oxygen enrichment.
Physical origin of the quadrupole out-of-plane magnetic field in Hall-magnetohydrodynamic-of-plane component of the magnetic field inside a reconnection region is seen as an important signature of the Hall-magnetohydrodynamic and that the Petschek5 fast-reconnection mechanism cannot be realized in resistive magnetohydrodynamic MHD with uniform
Magnetic Reconnection in Two-Dimensional Magnetohydrodynamic Turbulence S. Servidio,1
Shay, Michael
Magnetic Reconnection in Two-Dimensional Magnetohydrodynamic Turbulence S. Servidio,1 W. H-dimensional magnetohydrodynamic turbulence reveals the presence of a large number of X-type neutral points where magnetic be expected to be of importance in more general circumstances, including magnetohydrodynamic (MHD) turbulence
Forward and inverse cascades in decaying two-dimensional electron magnetohydrodynamic turbulence
Haase, Markus
Forward and inverse cascades in decaying two-dimensional electron magnetohydrodynamic turbulence C magnetohydrodynamic EMHD turbulence in two dimensions is studied via high-resolution numerical simulations's magnetosphere. Turbulence governed by Eq. 1 is known as electron magnetohydrodynamic EMHD , Hall MHD
Energy Decay Laws in Strongly Anisotropic Magnetohydrodynamic Turbulence Barbara Bigot,1,2
Paris-Sud XI, Université de
Energy Decay Laws in Strongly Anisotropic Magnetohydrodynamic Turbulence Barbara Bigot,1,2 Se the influence of a uniform magnetic field B0 B0ek on energy decay laws in incompressible magnetohydrodynamic uniform magnetic field on the energy decay laws in freely incompressible magnetohydrodynamic (MHD
Paris-Sud XI, Université de
Simulation of confined magnetohydrodynamic flows using a pseudo-spectral method with volume Abstract A volume penalization approach to simulate magnetohydrodynamic (MHD) flows in confined domains-instabilities, helical magnetic field, Taylor-Couette 1. Introduction Magnetohydrodynamics is the discipline that studies
Measurement of the Electric Fluctuation Spectrum of Magnetohydrodynamic Turbulence S. D. Bale,1
California at Berkeley, University of
Measurement of the Electric Fluctuation Spectrum of Magnetohydrodynamic Turbulence S. D. Bale,1 P June 2005) Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show the spectral, in particular, the physics of dissipation at small scales. The classical scenario of magnetohydrodynamic
Magnetohydrodynamic Turbulence Simulations on the Earth Simulator Using the Lattice Boltzmann
Oliker, Leonid
Magnetohydrodynamic Turbulence Simulations on the Earth Simulator Using the Lattice Boltzmann Method ABSTRACT Highly optimized large-scale lattice Boltzmann simulations of 3D magnetohydrodynamic) 2005 ACM 1-59593-061-2/05/0011...$5.00 1. INTRODUCTION Magnetohydrodynamics (or MHD) describes self
Compressible magnetohydrodynamic sawtooth crash
NASA Astrophysics Data System (ADS)
Sugiyama, Linda E.
2014-02-01
In a toroidal magnetically confined plasma at low resistivity, compressible magnetohydrodynamic (MHD) predicts that an m = 1/n = 1 sawtooth has a fast, explosive crash phase with abrupt onset, rate nearly independent of resistivity, and localized temperature redistribution similar to experimental observations. Large scale numerical simulations show that the 1/1 MHD internal kink grows exponentially at a resistive rate until a critical amplitude, when the plasma motion accelerates rapidly, culminating in fast loss of the temperature and magnetic structure inside q < 1, with somewhat slower density redistribution. Nonlinearly, for small effective growth rate the perpendicular momentum rate of change remains small compared to its individual terms ?p and J × B until the fast crash, so that the compressible growth rate is determined by higher order terms in a large aspect ratio expansion, as in the linear eigenmode. Reduced MHD fails completely to describe the toroidal mode; no Sweet-Parker-like reconnection layer develops. Important differences result from toroidal mode coupling effects. A set of large aspect ratio compressible MHD equations shows that the large aspect ratio expansion also breaks down in typical tokamaks with rq =1/Ro?1/10 and a /Ro?1/3. In the large aspect ratio limit, failure extends down to much smaller inverse aspect ratio, at growth rate scalings ? =O(?2). Higher order aspect ratio terms, including B?, become important. Nonlinearly, higher toroidal harmonics develop faster and to a greater degree than for large aspect ratio and help to accelerate the fast crash. The perpendicular momentum property applies to other transverse MHD instabilities, including m ? 2 magnetic islands and the plasma edge.
Seismic Halos around Active Regions: A Magnetohydrodynamic Theory
NASA Astrophysics Data System (ADS)
Hanasoge, Shravan M.
2008-06-01
Comprehending the manner in which magnetic fields affect propagating waves is a first step toward constructing accurate helioseismic models of active region subsurface structure and dynamics. Here we present a numerical method for computing the linear interaction of waves with magnetic fields embedded in a solar-like stratified background. The ideal magnetohydrodynamic (MHD) equations are solved in a three-dimensional box that straddles the solar surface, extending from 35 Mm below the photosphere to 1.2 Mm into the atmosphere. One of the challenges in performing these simulations involves generating a magnetohydrostatic (MHS) state wherein the stratification assumes horizontal inhomogeneity in addition to the strong vertical stratification associated with the near-surface layers. Keeping in mind that the aim of this effort is to understand and characterize linear MHD interactions, we discuss a means of computing statically consistent background states. Power maps computed from simulations of waves interacting with thick flux tubes that have peak photospheric field strengths of 600 and 3000 G are presented. Strong modal power reduction in the ``umbral'' regions of the flux tube enveloped by a halo of increased wave power is seen in the simulations with the thick flux tubes. These enhancements are also seen in Doppler velocity power maps of active regions observed in the Sun, which leads us to propose that the halo has MHD underpinnings.
Parameter space study of magnetohydrodynamic flows around magnetized compact objects
Santabrata Das; Sandip K. Chakrabarti
2007-06-20
We solve the magnetohydrodynamic (MHD) equations governing axisymmetric flows around neutron stars and black holes and found all possible solution topologies for adiabatic accretion. We divide the parameter space spanned by the conserved energy and angular momentum of the flow in terms of the flow topologies. We also study the possibility of the formation of the MHD shock waves.
Benjamin D. G. Chandran
2000-11-03
Scattering rates for a Goldreich-Sridhar (GS) spectrum of anisotropic, incompressible, magnetohydrodynamic turbulence are calculated in the quasilinear approximation. Because the small-scale fluctuations are constrained to have wave vectors nearly perpendicular to the background magnetic field, scattering is too weak to provide either the mean free paths commonly used in Galactic cosmic-ray propagation models or the mean free paths required for acceleration of cosmic rays at quasi-parallel shocks. Where strong pitch-angle scattering occurs, it is due to fluctuations not described by the GS spectrum, such as fluctuations generated by streaming cosmic rays.
Parallel, AMR MHD for Global Space Weather Simulations
Kenneth G. Powell; Darren L. De Zeeuw; Igor V. Sokolov; Gábor Tóth; Tamas Gombosi; Quentin Stout
This paper presents the methodology behind and results of adaptive mesh refinement in global magnetohydrodynamic models of the space environment. Techniques used in solving the governing equations of semi-relativistic magnetohydrodynamics (MHD) are presented. These techniques include high-resolution upwind schemes, block-based solution-adaptive grids, explicit, implicit and partial-implicit time-stepping, and domain decomposition for parallelization. Recent work done in coupling the MHD model
Shepard, W.S.; Cook, R.L.
1991-12-31
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for magnetohydrodynamic (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 (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 DIAL`S computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel 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.
Not Available
1994-07-01
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for magnetohydrodynamic (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 (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 DIAL`s computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel 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.
The magnetohydrodynamic equilibrium of coronal helmet streamers
S. Cuperman; C. Bruma; M. Dryer; M. Semel
1995-01-01
The equilibrium of coronal helmet streamers is investigated within the framework of an axisymmetric magnetohydrodynamic polytropic model. The main features of this work are: (i) The eight MHD vector equations are reduced - via analytical manipulations - to three scalar equations involving the magnetic flux function, the current density and temperature; (ii) The reduced system of equations is solved by
Magneto-hydrodynamically stable axisymmetric mirrors
Dmitri Ryutov
2010-01-01
The achievement of high beta (60%) plasma with near classical confinement in a linear axisymmetric magnetic configuration has sparked interest in the Gas Dynamic Trap concept. The significance of these results is that they can be projected directly to a neutron source for materials testing. The possibility of axisymmetric mirrors (AM) being magneto-hydrodynamically (MHD) stable is also of interest from
Global Magnetohydrodynamic Modeling of the Solar Corona
NASA Technical Reports Server (NTRS)
Linker, Jon A.
2001-01-01
This report describes the progress made in the investigation of the solar corona using magnetohydrodynamic (MHD) simulations. Coronal mass ejections (CME) are believed to be the primary cause of nonrecurrent geomagnetic storms and these have been investigated through the use of three-dimensional computer simulation.
Lattice Boltzmann model for simulation of magnetohydrodynamics
Shiyi Chen; Hudong Chen; Daniel Martinez; William Matthaeus
1991-01-01
A numerical method, based on a discrete Boltzmann equation, is presented for solving the equations of magnetohydrodynamics (MHD). The algorithm provides advantages similar to the cellular automaton method in that it is local and easily adapted to parallel computing environments. Because of much lower noise levels and less stringent requirements on lattice size, the method appears to be more competitive
Frutos-Alfaro, Francisco
2015-01-01
A program to generate codes in Fortran and C of the full Magnetohydrodynamic equations is shown. The program used the free computer algebra system software REDUCE. This software has a package called EXCALC, which is an exterior calculus program. The advantage of this program is that it can be modified to include another complex metric or spacetime. The output of this program is modified by means of a LINUX script which creates a new REDUCE program to manipulate the MHD equations to obtain a code that can be used as a seed for a MHD code for numerical applications. As an example, we present part of output of our programs for Cartesian coordinates and how to do the discretization.
Magnetohydrodynamic Origin of Jets from Accretion Disks
R. V. E. Lovelace; G. V. Ustyugova; A. V. Koldoba
1999-01-19
A review is made of recent magnetohydrodynamic (MHD) theory and simulations of origin of jets from accretion disks. Many compact astrophysical objects emit powerful, highly-collimated, oppositely directed jets. Included are the extra galactic radio jets of active galaxies and quasars, and old compact stars in binaries, and emission line jets in young stellar objects. It is widely thought that these different jets arise from rotating, conducting accretion disks threaded by an ordered magnetic field. The twisting of the magnetic field by the rotation of the disk drives the jets by magnetically extracting matter, angular momentum, and energy from the accretion disk. Two main regimes have been discussed theoretically, hydromagnetic winds which have a significant mass flux, and Poynting flux jets where the mass flux is negligible. Over the past several years, exciting new developments on models of jets have come from progress in MHD simulations which now allow the study of the origin - the acceleration and collimation - of jets from accretion disks. Simulation studies in the hydromagnetic wind regime indicate that the outflows are accelerated close to their region of origin whereas the collimation occurs at much larger distances.
Yu. G. Ignatyev
2011-01-05
On the basis of simple principles we derive and investigate the equations of relativistic plasma magnetohydrodynamics (MHD) in an arbitrary gravitational field. An exact solution describing the motion of magnetoactive plasma against the background of the metric of a plane gravitational wave (PGW) with an arbitrary amplitude is obtained. It is shown that in strong magnetic fields even a sufficiently small amplitude PGW can create a shock MHD wave, propagating at a subluminal velocity. Astrophysical consequences of the anomalous plasma acceleration are considered.
NONIDEAL MAGNETOHYDRODYNAMIC TURBULENT DECAY IN MOLECULAR CLOUDS
Downes, T. P. [School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); O'Sullivan, S. [National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland)], E-mail: turlough.downes@dcu.ie
2009-08-20
It is well known that nonideal magnetohydrodynamic (MHD) effects are important in the dynamics of molecular clouds: both ambipolar diffusion and possibly the Hall effect have been identified as significant. We present the results of a suite of simulations with a resolution of 512{sup 3} of turbulent decay in molecular clouds, incorporating a simplified form of both ambipolar diffusion and the Hall effect simultaneously. The initial velocity field in the turbulence is varied from being super-Alfvenic and hypersonic, through to trans-Alfvenic but still supersonic. We find that ambipolar diffusion increases the rate of decay of the turbulence increasing the decay from t {sup -1.25} to t {sup -1.4}. The Hall effect has virtually no impact in this regard. The power spectra of density, velocity, and the magnetic field are all affected by the nonideal terms, being steepened significantly when compared with ideal MHD turbulence with exponents. The density power-spectra components change from {approx}1.4 to {approx}2.1 for the ideal and nonideal simulations respectively, and power spectra of the other variables all show similar modifications when nonideal effects are considered. Again, the dominant source of these changes is ambipolar diffusion rather than the Hall effect. There is also a decoupling between the velocity field and the magnetic field at short length scales. The Hall effect leads to enhanced magnetic reconnection, and hence less power, at short length scales. The dependence of the velocity dispersion on the characteristic length scale is studied and found not to be power law in nature.
On the possibility of using an electromagnetic ionosphere in global MHD simulations
Paris-Sud XI, Université de
On the possibility of using an electromagnetic ionosphere in global MHD simulations P. Janhunen magnetohydrodynamic (MHD) simu- lations of the Earth's magnetosphere must be coupled with a dynamical ionospheric) from the magnetospheric MHD variables at the ionospheric boundary. The ionospheric potential is solved
Yu, Xinwei
2012-01-01
magnetohydrodynamic turbulence in two and three dimensions Chuong V. Tran and Xinwei Yu School of Mathematics; published 28 June 2012) We study incompressible magnetohydrodynamic turbulence in both two and three In incompressible magnetohydrodynamic (MHD) turbu- lence, the total (kinetic plus magnetic) energy is conserved
Magneto-hydrodynamics simulation study of deflagration mode in co-axial plasma accelerators
Sitaraman, Hariswaran; Raja, Laxminarayan L. [Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712 (United States)
2014-01-15
Experimental studies by Poehlmann et al. [Phys. Plasmas 17(12), 123508 (2010)] on a coaxial electrode magnetohydrodynamic (MHD) plasma accelerator have revealed two modes of operation. A deflagration or stationary mode is observed for lower power settings, while higher input power leads to a detonation or snowplow mode. A numerical modeling study of a coaxial plasma accelerator using the non-ideal MHD equations is presented. The effect of plasma conductivity on the axial distribution of radial current is studied and found to agree well with experiments. Lower conductivities lead to the formation of a high current density, stationary region close to the inlet/breech, which is a characteristic of the deflagration mode, while a propagating current sheet like feature is observed at higher conductivities, similar to the detonation mode. Results confirm that plasma resistivity, which determines magnetic field diffusion effects, is fundamentally responsible for the two modes.
NASA Technical Reports Server (NTRS)
Staigner, P. J.; Abbott, J. M.
1980-01-01
Two parallel contracted studies were conducted. Each contractor investigated three base cases and parametric variations about these base cases. Each contractor concluded that two of the base cases (a plant using separate firing of an advanced high temperature regenerative air heater with fuel from an advanced coal gasifier and a plant using an intermediate temperature metallic recuperative heat exchanger to heat oxygen enriched combustion air) were comparable in both performance and cost of electricity. The contractors differed in the level of their cost estimates with the capital cost estimates for the MHD topping cycle and the magnet subsystem in particular accounting for a significant part of the difference. The impact of the study on the decision to pursue a course which leads to an oxygen enriched plant as the first commercial MHD plant is described.
Status of power generation experiments in the NASA Lewis closed cycle MHD facility
NASA Technical Reports Server (NTRS)
Sovie, R. J.; Nichols, L. D.
1971-01-01
The design and operation of the closed cycle MHD facility is discussed and results obtained in recent experiments are presented. The main components of the facility are a compressor, recuperative heat exchanger, heater, nozzle, MHD channel with 28 pairs of thoriated tungsten electrodes, cesium condenser, and an argon cooler. The facility has been operated at temperatures up to 2100 K with a cesium-seeded argon working fluid. At low magnetic field strengths, the open circuit voltage, Hall voltage and short circuit current obtained are 90, 69, and 47 percent of the theoretical equilibrium values, respectively. Comparison of this data with a wall and boundary layer leakage theory indicates that the generator has shorting paths in the Hall direction.
Alfven Wave Tomography for Cold MHD Plasmas
I.Y. Dodin; N.J. Fisch
2001-09-07
Alfven waves propagation in slightly nonuniform cold plasmas is studied by means of ideal magnetohydrodynamics (MHD) nonlinear equations. The evolution of the MHD spectrum is shown to be governed by a matrix linear differential equation with constant coefficients determined by the spectrum of quasi-static plasma density perturbations. The Alfven waves are shown not to affect the plasma density inhomogeneities, as they scatter off of them. The application of the MHD spectrum evolution equation to the inverse scattering problem allows tomographic measurements of the plasma density profile by scanning the plasma volume with Alfven radiation.
Kleczek
1960-01-01
The basic relation between plasma and electromagnetic field is defined. ; The electrical conductivity of plasma is most important, and is really the basis ; of magnetohydrodynamics. As a conductor, plasma is acted on by the magnetic ; field. Other basic comments made are: waves in plasma, are analogous to sound ; waves, they carry electric charges, and can move
Gravitational radiation from primordial helical inverse cascade magnetohydrodynamic turbulence
Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Astrophysical Observatory, Ilia Chavchavadze State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Campanelli, Leonardo [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); INFN - Sezione di Bari, I-70126 Bari (Italy); Gogoberidze, Grigol [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); National Astrophysical Observatory, Ilia Chavchavadze State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Maravin, Yurii; Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)
2008-12-15
We consider the generation of gravitational waves by primordial helical inverse-cascade magnetohydrodynamic (MHD) turbulence produced by bubble collisions at the electroweak phase transition. We extend the previous study 1 by considering both currently discussed models of MHD turbulence. For popular electroweak phase transition parameter values, the generated gravitational wave spectrum is only weakly dependent on the MHD turbulence model. Compared with the unmagnetized electroweak phase transition case, the spectrum of MHD-turbulence-generated gravitational waves peaks at lower frequency with larger amplitude and can be detected by the proposed Laser Interferometer Space Antenna.
Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.
2008-01-01
Over the past several years, efforts have been under way to design and develop an operationally flexible research facility for investigating the use of cross-field MHD accelerators as a potential thrust augmentation device for thermal propulsion systems. The baseline configuration for this high-power experimental facility utilizes a 1.5-MWe multi-gas arc-heater as a thermal driver for a 2-MWe MHD accelerator, which resides in a large-bore 2-tesla electromagnet. A preliminary design study using NaK seeded nitrogen as the working fluid led to an externally diagonalized segmented MHD channel configuration based on an expendable heat-sink design concept. The current status report includes a review of engineering/design work and performance optimization analyses and summarizes component hardware fabrication and development efforts, preliminary testing results, and recent progress toward full-up assembly and testing
Hall magnetohydrodynamic ballooning instability in the magnetotail
NASA Astrophysics Data System (ADS)
Zhu, P.; Bhattacharjee, A.; Ma, Z. W.
2003-01-01
The ballooning stability of the magnetotail is considered within the framework of Hall magnetohydrodynamics (MHD). In particular, the extent to which Hall MHD effects modify ideal MHD ballooning modes is explored extensively. It is shown that Hall MHD effects primarily enter the stability analysis through changes introduced in the plasma compressibility. Hence, the incompressible ideal MHD modes are not affected, while the compressible ideal MHD modes are altered both quantitatively and qualitatively. In addition to modifying the growth rate of the compressible ideal MHD mode, Hall effects also introduce a new instability, called the entropy interchange instability, which is a variant of the ion temperature gradient instability, when the gradient ratio ??d ln Ti/d ln ? of the configuration becomes greater than 2/3, where Ti is the ion temperature and ? is the plasma density. The theory is applied to two types of magnetotail configurationsanalytic equilibria developed by Voigt [in Solar Wind-Magnetosphere Coupling, edited by Y. Kamide and J. A. Slavin (Terra Scientific, Tokyo, 1986), pp. 233-273], and more realistic magnetotail configurations containing thin current sheets obtained from Hall MHD simulations of substorm dynamics by Ma and Bhattacharjee [Geophys. Res. Lett. 25, 3277 (1998)].
De Sterck, Hans
between the fast MHD wave speed and roughly twice this speed, fast MHD switch-on shocks are possible.8 MHD of propagating shock fronts, and sup- ported by coronagraph observations of fast CMEs with a dimpled leadingComplex magnetohydrodynamic bow shock topology in field-aligned low- flow around a perfectly
Energy transfer and locality in magnetohydrodynamic turbulence
Mahendra K. Verma; Arvind Ayyer; Amar V. Chandra
2005-10-19
The shell-to-shell energy transfer rates for magnetohydrodynamic (MHD) turbulence are computed analytically, which shows local energy transfer rates from velocity to velocity, velocity to magnetic, magnetic to velocity, and magnetic to magnetic fields for nonhelical MHD in the inertial range. It is also found that for kinetic-energy dominated MHD fluid, there is a preferential shell-to-shell energy transfer from kinetic to magnetic energy; the transfer is reversed for magnetic-energy dominated MHD fluid. This property is the reason for the asymptotic value of Alfven ratio to be close to 0.5. The analytical results are in close agreement with recent numerical results. When magnetic and kinetic helicities are turned on, the helical contributions are opposite to the corresponding nonhelical contributions. The helical energy transfers have significant nonlocal components.
MHD performance demonstration experiment, October 1, 1080-September 30, 1981
Whitehead, G. L.; Christenson, L. S.; Felderman, E. J.; Lowry, R. L.; Bordenet, E. J.
1981-12-01
The Arnold Engineering Development Center (AEDC) has been under contract with the Department of Energy (DOE) since December 1973 to conduct a magnetohydrodynamic (MHD) High Performance Demonstration Experiment (HPDE). The objective of this experimental research is to demonstrate the attainment of MHD performance on a sufficiently large scale to verify that projected commercial MHD objectives are possible. This report describes the testing of the system under power-producing conditions during the period from October 1, 1980 to September 30, 1981. Experimental results have been obtained with the channel configured in the Faraday mode. Test conditions were selected to produce low supersonic velocity along the entire channel length. Tests have been conducted at magnetic fields up to 4.1 Tesla (T) (70% of design). Up to 30.5 MW of power has been produced to date (60% of design) for an enthalpy extraction of approximately 11%. The high Hall voltage transient, observed during the previous series of tests has been reduced. The reduction is mostly probably due to the fuel and seed being introduced simultaneously. The replacement of the ATJ graphite caps on the electrode walls with pyrolytic graphite caps has resulted in significantly higher surface temperature. As a result, the voltage drop is some 60% of the cold wall voltage drop during the previous series of tests. However, the absolute value of the present voltage drop is still greater than the original design predictions. Test results indicate, however, that the overall enthalpy extraction objective can be achieved.
Multiscaling in Hall-magnetohydrodynamic turbulence: insights from a shell model.
Banerjee, Debarghya; Ray, Samriddhi Sankar; Sahoo, Ganapati; Pandit, Rahul
2013-10-25
We show that a shell-model version of the three-dimensional Hall-magnetohydrodynamic (3D Hall-MHD) equations provides a natural theoretical model for investigating the multiscaling behaviors of velocity and magnetic structure functions. We carry out extensive numerical studies of this shell model, obtain the scaling exponents for its structure functions, in both the low-k and high-k power-law ranges of three-dimensional Hall-magnetohydrodynamic, and find that the extended-self-similarity procedure is helpful in extracting the multiscaling nature of structure functions in the high-k regime, which otherwise appears to display simple scaling. Our results shed light on intriguing solar-wind measurements. PMID:24206495
Micromachined magnetohydrodynamic actuators and sensors
Lee, Abraham P. (Walnut Creek, CA); Lemoff, Asuncion V. (Union City, CA)
2000-01-01
A magnetohydrodynamic (MHD) micropump and microsensor which utilizes micromachining to integrate the electrodes with microchannels and includes a magnet for producing magnetic fields perpendicular to both the electrical current direction and the fluid flow direction. The magnet can also be micromachined and integrated with the micropump using existing technology. The MHD micropump, for example, can generate continuous, reversible flow, with readily controllable flow rates. The flow can be reversed by either reversing the electrical current flow or reversing the magnetic field. By mismatching the electrodes, a swirling vortex flow can be generated for potential mixing applications. No moving parts are necessary and the dead volume is minimal. The micropumps can be placed at any position in a fluidic circuit and a combination of micropumps can generate fluidic plugs and valves.
Scaling Laws in Magnetohydrodynamic Turbulence
Leonardo Campanelli
2004-10-04
We analyze the decay laws of the kinetic and magnetic energies and the evolution of correlation lengths in freely decaying incompressible magnetohydrodynamic (MHD) turbulence. Scale invariance of MHD equations assures that, in the case of constant dissipation parameters ({\\it i.e.} kinematic viscosity and resistivity) and null magnetic helicity, the kinetic and magnetic energies decay in time as $E \\sim t^{-1}$, and the correlation lengths evolve as $\\xi \\sim t^{1/2}$. In the helical case, assuming that the magnetic field evolve towards a force-free state, we show that (in the limit of large magnetic Reynolds number) the magnetic helicity remains constant, the kinetic and magnetic energies decay as $E_v \\sim t^{-1}$ and $E_B \\sim t^{-1/2}$ respectively, while both the kinetic and magnetic correlation lengths grow as $\\xi \\sim t^{1/2}$.
Anomalous magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Giovannini, Massimo
2013-09-01
Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy of charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved coincide, in the perfectly conducting limit, with the ones obtainable in ideal magnetohydrodynamics where the anomalous currents are neglected. It is argued that this is the rationale for the ability to extend to anomalous magnetohydrodynamics the hydromagnetic solutions characterized by finite gyrotropy. The generally covariant aspects of the problem are addressed with particular attention to conformally flat geometries which are potentially relevant for the description of the electroweak plasma prior to the phase transition.
Long-term evolution of decaying magnetohydrodynamic turbulence in the multiphase interstellar medium
Kim, Chang-Goo [Currently at Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Basu, Shantanu, E-mail: ckim256@uwo.ca, E-mail: basu@uwo.ca, E-mail: cgkim@astro.princeton.edu [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)
2013-12-01
Supersonic turbulence in the interstellar medium (ISM) is believed to decay rapidly within a flow crossing time irrespective of the degree of magnetization. However, this general consensus of decaying magnetohydrodynamic (MHD) turbulence relies on local isothermal simulations, which are unable to take into account the roles of the global structures of magnetic fields and the ISM. Utilizing three-dimensional MHD simulations including interstellar cooling and heating, we investigate decaying MHD turbulence within cold neutral medium sheets embedded in a warm neutral medium. The early evolution of turbulent kinetic energy is consistent with previous results for decaying compressible MHD turbulence characterized by rapid energy decay with a power-law form of E?t {sup 1} and by a short decay time compared with the flow crossing time. If initial magnetic fields are strong and perpendicular to the sheet, however, long-term evolution of the kinetic energy shows that a significant amount of turbulent energy (?0.2E {sub 0}) still remains even after 10 flow crossing times for models with periodic boundary conditions. The decay rate is also greatly reduced as the field strength increases for such initial and boundary conditions, but not if the boundary conditions are those for a completely isolated sheet. We analyze velocity power spectra of the remaining turbulence to show that in-plane, incompressible motions parallel to the sheet dominate at later times.
MHD and Kinetic Modeling of the Ionospheres of Venus and Mars
Shinagawa, H.; Terada, N. [National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795 (Japan)
2009-06-16
It is widely recognized that both Venus and Mars possess no significant global intrinsic magnetic fields, and that the solar wind interacts directly with the upper atmospheres and ionospheres of Venus and Mars. In addition, local crustal magnetic fields are also present in various regions at Mars, suggesting that some regions of the Martian ionosphere are influenced not only by the solar wind but also by the crustal magnetic field. Previous studies have suggested that the basic structures of the ionospheres of the planets can be described by fluid and MHD(magnetohydrodynamic) processes. Various models of the ionospheres of Venus and Mars based on the MHD formulation have been constructed during the last two decades. Although the MHD approach has been successful in reproducing the ionospheres of the planets, some studies have indicated that MHD modeling is not necessarily appropriate in the regions of the topside ionosphere, the ionopause, and the magnetosheath, where the ion kinetic processes are likely to play an important role. The kinetic processes in the topside ionosphere might have significant influences even in the lower ionosphere. Thanks to a great progress made for computer power as well as the efficiency of calculations of the hybrid model, high-resolution kinetic models of the solar wind interaction with Venus and Mars, which self-consistently include the ionosphere, have been developed. In this paper, status of MHD and kinetic modeling of the ionospheres of Venus and Mars is briefly reviewed.
Multiscaling in Hall-Magnetohydrodynamic Turbulence: Insights from a Shell Model
Debarghya Banerjee; Samriddhi Sankar Ray; Ganapati Sahoo; Rahul Pandit
2013-03-04
We show that a shell-model version of the three-dimensional Hall-magnetohydrodynamic (3D Hall-MHD) equations provides a natural theoretical model for investigating the multiscaling behaviors of velocity and magnetic structure functions. We carry out extensive numerical studies of this shell model, obtain the scaling exponents for its structure functions, in both the low-$k$ and high-$k$ power-law ranges of 3D Hall-MHD, and find that the extended-self-similarity (ESS) procedure is helpful in extracting the multiscaling nature of structure functions in the high-$k$ regime, which otherwise appears to display simple scaling. Our results shed light on intriguing solar-wind measurements.
Multiscaling in Hall-Magnetohydrodynamic Turbulence: Insights from a Shell Model
Banerjee, Debarghya; Sahoo, Ganapati; Pandit, Rahul
2013-01-01
We show that a shell-model version of the three-dimensional Hall-magnetohydrodynamic (3D Hall-MHD) equations provides a natural theoretical model for investigating the multiscaling behaviors of velocity and magnetic structure functions. We carry out extensive numerical studies of this shell model, obtain the scaling exponents for its structure functions, in both the low-$k$ and high-$k$ power-law ranges of 3D Hall-MHD, and find that the extended-self-similarity (ESS) procedure is helpful in extracting the multiscaling nature of structure functions in the high-$k$ regime, which otherwise appears to display simple scaling. Our results shed light on intriguing solar-wind measurements.
Fundamental solution for coupled magnetohydrodynamic flow equations
NASA Astrophysics Data System (ADS)
Bozkaya, C.; Tezer-Sezgin, M.
2007-06-01
In this paper, a fundamental solution for the coupled convection-diffusion type equations is derived. The boundary element method (BEM) application then, is established with this fundamental solution, for solving the coupled equations of steady magnetohydrodynamic (MHD) duct flow in the presence of an external oblique magnetic field. Thus, it is possible to solve MHD duct flow problems with the most general form of wall conductivities and for large values of Hartmann number. The results for velocity and induced magnetic field is visualized in terms of graphics for values of Hartmann number M[less-than-or-equals, slant]300.
Magnetohydrodynamic turbulence in the solar wind
NASA Technical Reports Server (NTRS)
Goldstein, Melvyn L.
1995-01-01
The fluctuations in magnetic field and plasma velocity in solar wind, which possess many features of fully developed magnetohydrodynamic (MHD) turbulence, are discussed. Direct spacecraft observations from 0.3 to over 20 AU, remote sensing radio scintillation observations, numerical simulations, and various models provide complementary methods that show that the fluctuations in the wind parameters undergo significant dynamical evolution independent of whatever turbulence might exist in the solar photosphere and corona. The Cluster mission, with high time resolution particle and field measurements and its variable separation strategies, should be able to provide data for answering many questions on MHD turbulence.
NASA Technical Reports Server (NTRS)
Sovie, R. J.; Winter, J. M.; Juhasz, A. J.; Berg, R. D.
1982-01-01
A conceptual design study of the MHD/steam plant that incorporates the use of oxygen enriched air preheated in a metallic heat exchanger as the combustor oxidant showed that this plant is the most attractive for early commercial applications. The variation of performance and cost was investigated as a function of plant size. The contractors' results for the overall efficiencies are in reasonable agreement considering the slight differences in their plant designs. NASA LeRC is reviewing cost and performance results for consistency with those of previous studies, including studies of conventional steam plants. LeRC in house efforts show that there are still many tradeoffs to be considered for these oxygen enriched plants and considerable variations can be made in channel length and level of oxygen enrichment with little change in overall plant efficiency.
Numerical Measurements of the Spectrum in Magnetohydrodynamic Turbulence
Joanne Mason; Fausto Cattaneo; Stanislav Boldyrev
2007-06-13
We report the results of an extensive set of direct numerical simulations of forced, incompressible, magnetohydrodynamic turbulence with a strong guide field. The aim is to resolve the controversy regarding the power law exponent (\\alpha, say) of the field perpendicular energy spectrum E(k_\\perp) \\propto k_\\perp ^ {\\alpha}. The two main theoretical predictions, \\alpha=-3/2 and \\alpha=-5/3, have both received some support from numerical simulations carried out by different groups. Our simulations have a resolution of 512^3 mesh points, a strong guide field, an anisotropic simulation domain, and implement a broad range of large-scale forcing routines, including those previously reported in the literature. Our findings indicate that the spectrum of well developed, strong incompressible MHD turbulence with a strong guide field is E(k_{\\perp})\\propto k_{\\perp}^{-3/2}.
Self-organized criticality in MHD driven plasma edge turbulence
NASA Astrophysics Data System (ADS)
dos Santos Lima, G. Z.; Iarosz, K. C.; Batista, A. M.; Caldas, I. L.; Guimarăes-Filho, Z. O.; Viana, R. L.; Lopes, S. R.; Nascimento, I. C.; Kuznetsov, Yu. K.
2012-01-01
We analyze long-range time correlations and self-similar characteristics of the electrostatic turbulence at the plasma edge and scrape-off layer in the Tokamak Chauffage Alfvén Brésillien (TCABR), with low and high Magnetohydrodynamics (MHD) activity. We find evidence of self-organized criticality (SOC), mainly in the region near the tokamak limiter. Comparative analyses of data before and during the MHD activity reveals that during the high MHD activity the Hurst parameter decreases. Finally, we present a cellular automaton whose parameters are adjusted to simulate the analyzed turbulence SOC change with the MHD activity variation.
Three-dimensional hybrid gyrokinetic-magnetohydrodynamics simulation
Park, W.; Parker, S.; Biglari, H.; Chance, M.; Chen, L.; Cheng, C.Z.; Hahm, T.S.; Lee, W.W.; Kulsrud, R.; Monticello, D.; Sugiyama, L.; White, R. (Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States))
1992-07-01
A three-dimensional (3-D) hybrid gyrokinetic-MHD (magnetohydrodynamic) simulation scheme is presented. To the 3-D toroidal MHD code, MH3D-K the energetic particle component is added as gyrokinetic particles. The resulting code, MH3D is used to study the nonlinear behavior of energetic particle effects in tokamaks, such as the energetic particle stabilization of sawteeth, fishbone oscillations, and alpha-particle-driven toroidal Alfven eigenmode (TAE) modes.
Nonaxisymmetric, multi-region relaxed magnetohydrodynamic equilibrium solutions
S. R. Hudson; R. L. Dewar; M. J. Hole; M. McGann
2011-10-05
We describe a magnetohydrodynamic (MHD) constrained energy functional for equilibrium calculations that combines the topological constraints of ideal MHD with elements of Taylor relaxation. Extremizing states allow for partially chaotic magnetic fields and non-trivial pressure profiles supported by a discrete set of ideal interfaces with irrational rotational transforms. Numerical solutions are computed using the Stepped Pressure Equilibrium Code, SPEC, and benchmarks and convergence calculations are presented.
A Solution-Adaptive Upwind Scheme for Ideal Magnetohydrodynamics
Kenneth G. Powell; Philip L. Roe; Timur J. Linde; Tamas I. Gombosi; Darren L. De Zeeuw
1999-01-01
This paper presents a computational scheme for compressible magnetohydrodynamics (MHD). The scheme is based on the same elements that make up many modern compressible gas dynamics codes: a high-resolution upwinding based on an approximate Riemann solver for MHD and limited reconstruction; an optimally smoothing multi-stage time-stepping scheme; and solution-adaptive refinement and coarsening. In addition, a method for increasing the accuracy
NASA Astrophysics Data System (ADS)
Murakami, Tomoyuki; Zhuang, Yunqin; Okuno, Yoshihiro
2013-02-01
We describe high-density magnetohydrodynamic (MHD) energy conversion in a high-temperature seed-free argon plasma, for which a compact linear-shaped Faraday-type MHD electrical power generator is used. Short-time-duration single-pulse shock-tunnel-based experiments demonstrate the MHD energy conversion with varying total inflow temperature up to 9000 K and applied magnetic-flux density up to 4.0 T. The high-temperature plasma is transformed from the thermal-equilibrium state at the entrance to the weak-nonequilibrium state in the supersonic MHD channel. The discharge structure is reasonably homogeneous without suffering from serious streamer development. The power generation performance is monotonically improved by increasing total inflow temperature and strength of magnetic field. The enthalpy extraction efficiency of 13.1% and overall power density of 0.16 GW/m3 are attained. The local power density at the middle of the channel reaches 0.24 GW/m3.
Drift-magnetohydrodynamical model of error-field penetration in tokamak plasmas
Fitzpatrick, Richard
Drift-magnetohydrodynamical model of error-field penetration in tokamak plasmas A. Cole and R published magnetohydrodynamical MHD model of error-field penetration in tokamak plasmas is extended to take incorporated into the analysis. The new model is used to examine the scaling of the penetration threshold
Magneto-hydrodynamically stable axisymmetric mirrors
D. D. Ryutov; H. L. Berk; B. I. Cohen; A. W. Molvik; T. C. Simonen
2011-01-01
Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)
2014-09-15
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=?(?{sub 0}/p{sub 0}) I/(2 ?) where I is the current, ?{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ? R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then slows the shock Mach number growth producing a maximum followed by monotonic reduction towards magnetosonic conditions, even as the shock accelerates toward the axis. A parameter space of initial shock Mach number at a given radius is explored and the implications of the present results for inertial confinement fusion are discussed.
Converging cylindrical shocks in ideal magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.
2014-09-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{? _0/p_0} I/(2 ? ) where I is the current, ?0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ? R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then slows the shock Mach number growth producing a maximum followed by monotonic reduction towards magnetosonic conditions, even as the shock accelerates toward the axis. A parameter space of initial shock Mach number at a given radius is explored and the implications of the present results for inertial confinement fusion are discussed.
MHD coal-fired flow facility. Annual technical progress report, October 1979-September 1980
Alstatt, M.C.; Attig, R.C.; Brosnan, D.A.
1981-03-01
The University of Tennessee Space Institute (UTSI) reports on significant activity, task status, planned research, testing, development, and conclusions for the Magnetohydrodynamics (MHD) Coal-Fired Flow Faclity (CFFF) and the Energy Conversion Facility (ECF).
Rebound Shock Breakouts of Exploding Massive Stars: A MHD Void Model
Hu, Ren-Yu
2008-01-01
With a self-similar magnetohydrodynamic (MHD) model of an exploding progenitor star and an outgoing rebound shock and with the thermal bremsstrahlung as the major radiation mechanism in X-ray bands, we reproduce the early X-ray light curve observed for the recent event of XRO 080109/SN 2008D association. The X-ray light curve consists of a fast rise, as the shock travels into the "visible layer" in the stellar envelope, and a subsequent power-law decay, as the plasma cools in a self-similar evolution. The observed spectral softening is naturally expected in our rebound MHD shock scenario. We propose to attribute the "non-thermal spectrum" observed to be a superposition of different thermal spectra produced at different layers of the stellar envelope.
Rebound Shock Breakouts of Exploding Massive Stars: A MHD Void Model
Ren-Yu Hu; Yu-Qing Lou
2008-08-28
With a self-similar magnetohydrodynamic (MHD) model of an exploding progenitor star and an outgoing rebound shock and with the thermal bremsstrahlung as the major radiation mechanism in X-ray bands, we reproduce the early X-ray light curve observed for the recent event of XRO 080109/SN 2008D association. The X-ray light curve consists of a fast rise, as the shock travels into the "visible layer" in the stellar envelope, and a subsequent power-law decay, as the plasma cools in a self-similar evolution. The observed spectral softening is naturally expected in our rebound MHD shock scenario. We propose to attribute the "non-thermal spectrum" observed to be a superposition of different thermal spectra produced at different layers of the stellar envelope.
Tokamak Magnetohydrodynamic Equilibrium States with Axisymmetric Boundary and a 3D Helical Core
Cooper, W. A.; Graves, J. P.; Pochelon, A.; Sauter, O.; Villard, L. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland)
2010-07-16
Magnetohydrodynamic (MHD) equilibrium states with imposed axisymmetric boundary are computed in which a spontaneous bifurcation develops to produce an internal three-dimensional (3D) configuration with a helical structure in addition to the standard axisymmetric system. Equilibrium states with similar MHD energy levels are shown to develop very different geometric structures. The helical equilibrium states resemble saturated internal kink mode structures.
J. B. Jr. Dicks; H. P. Markant; R. C. Attig
1977-01-01
Tests conducted in the existing MHD facility supported areas critical to the design of components for the new intermediate-size, direct coal-fired MHD development facility. A new combustor design concept was developed and tested. In the coal to oxygen ratio studies, equilibrium combustion calculations of the combustion process were carried out for various values of oxidant ratio. This was done to
Global Magnetohydrodynamic Modeling of the Solar Corona
NASA Technical Reports Server (NTRS)
Linker, Jon A.
1997-01-01
Under this contract, we have continued our investigations of the large scale structure of the solar corona and inner heliosphere using global magnetohydrodynamic (MHD) simulations. These computations have also formed the basis for studies of coronal mass ejections (CMES) using realistic coronal configurations. We have developed a technique for computing realistic magnetohydrodynamic (MHD) computations of the solar corona and inner heliosphere. To perform computations that can be compared with specific observations, it is necessary to incorporate solar observations into the boundary conditions. We have used the Wilcox Solar Observatory synoptic maps (collected during a solar rotation by daily measurements of the line-of-sight magnetic field at central meridian) to specify the radial magnetic field (B,) at the photosphere. For the initial condition, we use a potential magnetic field consistent with the specified distribution of B, at the lower boundary, and a wind solution consistent with the specified plasma density and temperature at the solar surface. Together this initial condition forms a (non-equilibrium) approximation of the state of the solar corona for the time-dependent MHD computation. The MHD equations are then integrated in time to steady state. Here we describe solutions relevant to a recent solar eclipse, as well as Ulysses observations. We have also developed a model configuration of solar minimum, useful for studying CME initiation and propagation.
Feasibility of the inflow disk generator for open-cycle MHD power generation. Final report
Eustis, R.H.
1980-12-01
A feasibility study of the inflow disk MHD generator for baseload applications was performed. Each design element, i.e., the combustor, the inlet flow path, the generator channel, the diffuser and the magnet, was studied in detail in order to provide a comprehensive assessment of the inflow disk generator. A detailed comparative study of the heat loss effect of a single combustor vs multiple combustors for the inflow disk generator was conducted based on available combustor scaling laws. The heat and momentum losses in the inlet path were calculated for the combustion gas of Montana Rosebud coal with preheated air under the slagging wall condition. The tangential variation of the thermodynamic and electrical properties at the inlet of the channel due to these losses was calculated, and its effect on the generator performance was estimated. A series of water flow visualization experiments was conducted using a scale model of a baseload generator in order to study the flow field at the generator inlet. The performance of the conical diffuser to be combined with the inflow disk generator was estimated based on the available data. The intensity and the distribution of the magnetic field were calculated for the single-coil magnet and for the split-pair magnet. Based on these results, the performance of the inflow disk generator was calculated for two different thermal inputs: 1250 MW(th) and 2500 MW(th). It was shown that the performance of the inflow disk generator is similar to that of the diagonal generator within the uncertainty of the analysis.
Nuclear magnetohydrodynamic EMP, solar storms, and substorms
Rabinowitz, M. (Electric Power Research Inst., Palo Alto, CA (United States)); Meliopoulous, A.P.S.; Glytsis, E.N. (Georgia Inst. of Tech., Atlanta, GA (United States). School of Electrical Engineering); Cokkinides, G.J. (Electrical Engineering Dept., Univ. of South Carolina, Columbia, SC (United States))
1992-10-20
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[sup [minus] 1] V/m and lasts [approx lt] 10[sup 2] sec, whereas for solar storms E [approx gt] 10[sup [minus] 2] V/m and lasts [approx gt] 10[sup 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.
The magnetohydrodynamics model of twin kilohertz QPOs in LMXBs
Changsheng Shi; Xiang-Dong Li
2008-10-10
We suggest an explanation for the twin kilohertz quasi-periodic oscillations (kHz QPOs) in low-mass X-ray binaries (LMXBs) based on magnetohydrodynamics (MHD) oscillation modes in neutron star magnetospheres. Including the effect of the neutron star spin, we derive several MHD wave modes by solving the dispersion equations, and propose that the coupling of the two resonant MHD modes may lead to the twin kHz QPOs. This model naturally relates the upper, lower kHz QPO frequencies with the spin frequencies of the neutron stars, and can well account for the measured data of six LMXBs.
Nearly incompressible fluids. II - Magnetohydrodynamics, turbulence, and waves
NASA Technical Reports Server (NTRS)
Zank, G. P.; Matthaeus, W. H.
1993-01-01
The theory of nearly incompressible (NI) fluid dynamics developed previously for hydrodynamics is extended to magnetohydrodynamics (MHD). Based on a singular expansion technique, modified systems of fluid equations are obtained for which the effects of compressibility are admitted only weakly in terms of the different possible incompressible solutions. NI MHD represents the interface between the compressible and incompressible magnetofluid descriptions in the subsonic regime. It is shown that three distinct NI descriptions exist corresponding to each of the three possible plasma beta regimes. The detailed theory of weakly compressible corrections to the various incompressible MHD descriptions is presented, and the implications for the solar wind are discussed.
Computation of multi-region relaxed magnetohydrodynamic equilibria
Hudson, S. R.; Lazerson, S. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Dewar, R. L.; Dennis, G.; Hole, M. J.; McGann, M.; Nessi, G. von [Plasma Research Laboratory, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)
2012-11-15
We describe the construction of stepped-pressure equilibria as extrema of a multi-region, relaxed magnetohydrodynamic (MHD) energy functional that combines elements of ideal MHD and Taylor relaxation, and which we call MRXMHD. The model is compatible with Hamiltonian chaos theory and allows the three-dimensional MHD equilibrium problem to be formulated in a well-posed manner suitable for computation. The energy-functional is discretized using a mixed finite-element, Fourier representation for the magnetic vector potential and the equilibrium geometry; and numerical solutions are constructed using the stepped-pressure equilibrium code, SPEC. Convergence studies with respect to radial and Fourier resolution are presented.
NASA Technical Reports Server (NTRS)
Retallick, F. D.
1980-01-01
Directly-fired, separately-fired, and oxygen-augmented MHD power plants incorporating a disk geometry for the MHD generator were studied. The base parameters defined for four near-optimum-performance MHD steam power systems of various types are presented. The finally selected systems consisted of (1) two directly fired cases, one at 1920 K (2996F) preheat and the other at 1650 K (2500 F) preheat, (2) a separately-fired case where the air is preheated to the same level as the higher temperature directly-fired cases, and (3) an oxygen augmented case with the same generator inlet temperature of 2839 (4650F) as the high temperature directly-fired and separately-fired cases. Supersonic Mach numbers at the generator inlet, gas inlet swirl, and constant Hall field operation were specified based on disk generator optimization. System pressures were based on optimization of MHD net power. Supercritical reheat stream plants were used in all cases. Open and closed cycle component costs are summarized and compared.
Low-frequency circuit analysis of MHD-EMP-induced transients on three-phase distribution systems
Mayhall, D.J.; Yee, J.H.
1992-07-01
The magnetohydrodynamic electromagnetic pulse (MHD-EMP) generated by a nuclear explosion in the earth`s ionosphere is believed by a number of researchers to pose a potentially severe threat to long electric utility transmission and distribution systems in the United States. The disturbances caused by MHD-EMP are similar to the electromagnetic transients caused by solar-induced geomagnetic storms, but are generally expected to be more intense with shorter durations. Recent solar-induced storms have caused appreciable damage to electric utility equipment in Canada and the northern United States. In March of 1989, a solar-induced geomagnetic storm caused a blackout of the Hydro-Quebec power system in the province of Quebec, failure of step-up power transformers at the Salem Nuclear Generating Plant of the Public Service Electric and Gas Company, and a number of less severe power disruptions in the United States. Since the amplitudes of MHD-EMP induced transients are expected to be stronger than those produced by solar-induced geomagnetic storms, unprotected electric utility power systems may be quite vulnerable to MHD-EMP.
Low-frequency circuit analysis of MHD-EMP-induced transients on three-phase distribution systems
Mayhall, D.J.; Yee, J.H.
1992-07-01
The magnetohydrodynamic electromagnetic pulse (MHD-EMP) generated by a nuclear explosion in the earth's ionosphere is believed by a number of researchers to pose a potentially severe threat to long electric utility transmission and distribution systems in the United States. The disturbances caused by MHD-EMP are similar to the electromagnetic transients caused by solar-induced geomagnetic storms, but are generally expected to be more intense with shorter durations. Recent solar-induced storms have caused appreciable damage to electric utility equipment in Canada and the northern United States. In March of 1989, a solar-induced geomagnetic storm caused a blackout of the Hydro-Quebec power system in the province of Quebec, failure of step-up power transformers at the Salem Nuclear Generating Plant of the Public Service Electric and Gas Company, and a number of less severe power disruptions in the United States. Since the amplitudes of MHD-EMP induced transients are expected to be stronger than those produced by solar-induced geomagnetic storms, unprotected electric utility power systems may be quite vulnerable to MHD-EMP.
Extension of the Piecewise Parabolic Method to Multidimensional Ideal Magnetohydrodynamics
Wenlong Dai; Paul R. Woodward
1994-01-01
An extension of the piecewise parabolic method to treat multidimensional ideal magnetohydrodynamical equations is presented in this paper. The multidimensional scheme is constructed from a one-dimensional functioning code based on the dimensional splitting method originally suggested by Strang. The functioning code is built upon a nonlinear Riemann solver for ideal MHD equations recently developed by the authors. The correctness of
NASA Astrophysics Data System (ADS)
Daldorff, L. K. S.; Toth, G.; Borovikov, D.; Gombosi, T. I.; Lapenta, G.
2014-12-01
With the new modeling capability in the Space Weather Modeling Framework (SWMF) of embedding an implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US magnetohydrodynamics model (Daldorff et al. 2014, JCP, 268, 236) we are ready to locally handle the full physics of the reconnection and its implications on the full system where globally, away from the reconnection region, a magnetohydrodynamic description is satisfactory. As magnetic reconnection is one of the main drivers in magnetospheric and heliospheric plasma dynamics, the self-consistent description of the electron dynamics in the coupled MHD-EPIC model is well suited for investigating the nature of these systems. We will compare the new embedded MHD-EPIC model with pure MHD and Hall MHD simulations of the Earth's magnetosphere.
NASA Astrophysics Data System (ADS)
Chuvatin, Alexandre S.; Rudakov, Leonid I.; Kokshenev, Vladimir A.; Aranchuk, Leonid E.; Huet, Dominique; Gasilov, Vladimir A.; Krukovskii, Alexandre Yu.; Kurmaev, Nikolai E.; Fursov, Fiodor I.
2002-12-01
This work introduces an inductive energy storage (IES) scheme which aims pulsed-power conditioning at multi- MJ energies. The key element of the scheme represents an additional plasma volume, where a magnetically accelerated wire array is used for inductive current switching. This plasma acceleration volume is connected in parallel to a microsecond capacitor bank and to a 100-ns current ruse-time useful load. Simple estimates suggest that optimized scheme parameters could be reachable even when operating at ultra-high currents. We describe first proof-of-principle experiments carried out on GIT12 generator [1] at the wire-array current level of 2 MA. The obtained confirmation of the concept consists in generation of a 200 kV voltage directly at an inductive load. This load voltage value can be already sufficient to transfer the available magnetic energy into kinetic energy of a liner at this current level. Two-dimensional modeling with the radiational MHD numerical tool Marple [2] confirms the development of inductive voltage in the system. However, the average voltage increase is accompanied by short-duration voltage drops due to interception of the current by the low-density upstream plasma. Upon our viewpoint, this instability of the current distribution represents the main physical limitation to the scheme performance.
An adaptive MHD method for global space weather simulations
Darren L. De Zeeuw; Tamas I. Gombosi; Clinto P. T. Groth; Kenneth G. Powell; Quentin F. Stout
2000-01-01
A 3D parallel adaptive mesh refinement (AMR) scheme is described for solving the partial-differential equations governing ideal magnetohydrodynamic (MHD) flows. This new algorithm adopts a cell-centered upwind finite-volume discretization procedure and uses limited solution reconstruction, approximate Riemann solvers, and explicit multi-stage time stepping to solve the MHD equations in divergence form, providing a combination of high solution accuracy and computational
MHD processes in the outer heliosphere
NASA Technical Reports Server (NTRS)
Burlaga, L. F.
1984-01-01
The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
Line-tied MHD modes: effect of plasma pressure, axial boundary condition and axial flow
Francesco Arcudi; Gian Luca Delzanno; John M. Finn
2008-01-01
Recent 3D nonlinear magnetohydrodynamic (MHD) simulations of astrophysical jets [1] showed a narrow jet-like region with very tightly wound magnetic fields, very suggestive of jet observations. These results were unexpected because such tightly wound magnetic fields should be violently MHD unstable. In order to make direct contact with the simulations of Ref. [1], we present a linear stability study in
Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH). Part 1
NASA Technical Reports Server (NTRS)
Micheletti, David A.; Baughman, Jack A.; Nelson, Gordon L.; Simmons, Gloyd A.
1997-01-01
This report documents the activities, results, conclusions and recommendations of the Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH) Project in which the use of magnetohydrodynamics (MHD) technology is investigated for its applicability to augment hypersonic wind tunnels. The long range objective of this investigation is to advance the development of ground test facilities to support the development of hypervelocity flight vehicles. The MHD accelerator adds kinetic energy directly to the wind tunnel working fluid, thereby increasing its Mach number to hypervelocity levels. Several techniques for MHD augmentation, as well as other physical characteristics of the process are studied to enhance the overall performance of hypersonic wind tunnel design. Specific recommendations are presented to improve the effectiveness of ground test facilities. The work contained herein builds on nearly four decades of research and experimentation by the aeronautics ground test and evaluation community, both foreign and domestic.
Magnetohydrodynamics Accelerator Research into Advanced Hypersonics (MARIAH). Part 2
NASA Technical Reports Server (NTRS)
Baughman, Jack A.; Micheletti, David A.; Nelson, Gordon L.; Simmons, Gloyd A.
1997-01-01
This report documents the activities, results, conclusions and recommendations of the Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH) Project in which the use of magnetohydrodynamics (MHD) technology is investigated for its applicability to augment hypersonic wind tunnels. The long range objective of this investigation is to advance the development of ground test facilities to support the development of hypervelocity flight vehicles. The MHD accelerator adds kinetic energy directly to the wind tunnel working fluid, thereby increasing its Mach number to hypervelocity levels. Several techniques for MHD augmentation, as well as other physical characteristics of the process are studied to enhance the overall performance of hypersonic wind tunnel design. Specific recommendations are presented to improve the effectiveness of ground test facilities. The work contained herein builds on nearly four decades of research and experimentation by the aeronautics ground test and evaluation community, both foreign and domestic.
Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft
NASA Astrophysics Data System (ADS)
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.
Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft
Myrabo, L.N. [Mechanical, Aerospace, and Nuclear Engineering Dept., Rensselaer Polytechnic Institute, Troy, NY (United States); Rosa, R.J. [Department of Mechanical Engineering, Montana State University, Bozeman, MT (United States)
2004-03-30
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.
Coronal magnetohydrodynamic waves and oscillations: observations and quests.
Aschwanden, Markus J
2006-02-15
Coronal seismology, a new field of solar physics that emerged over the last 5 years, provides unique information on basic physical properties of the solar corona. The inhomogeneous coronal plasma supports a variety of magnetohydrodynamics (MHD) wave modes, which manifest themselves as standing waves (MHD oscillations) and propagating waves. Here, we briefly review the physical properties of observed MHD oscillations and waves, including fast kink modes, fast sausage modes, slow (acoustic) modes, torsional modes, their diagnostics of the coronal magnetic field, and their physical damping mechanisms. We discuss the excitation mechanisms of coronal MHD oscillations and waves: the origin of the exciter, exciter propagation, and excitation in magnetic reconnection outflow regions. Finally, we consider the role of coronal MHD oscillations and waves for coronal heating, the detectability of various MHD wave types, and we estimate the energies carried in the observed MHD waves and oscillations: Alfvénic MHD waves could potentially provide sufficient energy to sustain coronal heating, while acoustic MHD waves fall far short of the required coronal heating rates. PMID:16414888
Diffusive Acceleration of Particles at Oblique, Relativistic, Magnetohydrodynamic Shocks
NASA Astrophysics Data System (ADS)
Summerlin, Errol J.; Baring, Matthew G.
2012-01-01
Diffusive shock acceleration (DSA) at relativistic shocks is expected to be an important acceleration mechanism in a variety of astrophysical objects including extragalactic jets in active galactic nuclei and gamma-ray bursts. These sources remain good candidate sites for the generation of ultrahigh energy cosmic rays. In this paper, key predictions of DSA at relativistic shocks that are germane to the production of relativistic electrons and ions are outlined. The technique employed to identify these characteristics is a Monte Carlo simulation of such diffusive acceleration in test-particle, relativistic, oblique, magnetohydrodynamic (MHD) shocks. Using a compact prescription for diffusion of charges in MHD turbulence, this approach generates particle angular and momentum distributions at any position upstream or downstream of the shock. Simulation output is presented for both small angle and large angle scattering scenarios, and a variety of shock obliquities including superluminal regimes when the de Hoffmann-Teller frame does not exist. The distribution function power-law indices compare favorably with results from other techniques. They are found to depend sensitively on the mean magnetic field orientation in the shock, and the nature of MHD turbulence that propagates along fields in shock environs. An interesting regime of flat-spectrum generation is addressed; we provide evidence for it being due to shock drift acceleration, a phenomenon well known in heliospheric shock studies. The impact of these theoretical results on blazar science is outlined. Specifically, Fermi Large Area Telescope gamma-ray observations of these relativistic jet sources are providing significant constraints on important environmental quantities for relativistic shocks, namely, the field obliquity, the frequency of scattering, and the level of field turbulence.
RESONANCE BROADENING AND HEATING OF CHARGED PARTICLES IN MAGNETOHYDRODYNAMIC TURBULENCE
Lynn, Jacob W. [Physics Department, University of California, Berkeley, CA 94720 (United States); Parrish, Ian J.; Quataert, Eliot [Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States); Chandran, Benjamin D. G., E-mail: jacob.lynn@berkeley.edu [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)
2012-10-20
The heating, acceleration, and pitch-angle scattering of charged particles by magnetohydrodynamic (MHD) turbulence are important in a wide range of astrophysical environments, including the solar wind, accreting black holes, and galaxy clusters. We simulate the interaction of high-gyrofrequency test particles with fully dynamical simulations of subsonic MHD turbulence, focusing on the parameter regime with {beta} {approx} 1, where {beta} is the ratio of gas to magnetic pressure. We use the simulation results to calibrate analytical expressions for test particle velocity-space diffusion coefficients and provide simple fits that can be used in other work. The test particle velocity diffusion in our simulations is due to a combination of two processes: interactions between particles and magnetic compressions in the turbulence (as in linear transit-time damping; TTD) and what we refer to as Fermi Type-B (FTB) interactions, in which charged particles moving on field lines may be thought of as beads sliding along moving wires. We show that test particle heating rates are consistent with a TTD resonance that is broadened according to a decorrelation prescription that is Gaussian in time (but inconsistent with Lorentzian broadening due to an exponential decorrelation function, a prescription widely used in the literature). TTD dominates the heating for v{sub s} >> v{sub A} (e.g., electrons), where v{sub s} is the thermal speed of species s and v{sub A} is the Alfven speed, while FTB dominates for v{sub s} << v{sub A} (e.g., minor ions). Proton heating rates for {beta} {approx} 1 are comparable to the turbulent cascade rate. Finally, we show that velocity diffusion of collisionless, large gyrofrequency particles due to large-scale MHD turbulence does not produce a power-law distribution function.
Resonance Broadening and Heating of Charged Particles in Magnetohydrodynamic Turbulence
NASA Astrophysics Data System (ADS)
Lynn, Jacob W.; Parrish, Ian J.; Quataert, Eliot; Chandran, Benjamin D. G.
2012-10-01
The heating, acceleration, and pitch-angle scattering of charged particles by magnetohydrodynamic (MHD) turbulence are important in a wide range of astrophysical environments, including the solar wind, accreting black holes, and galaxy clusters. We simulate the interaction of high-gyrofrequency test particles with fully dynamical simulations of subsonic MHD turbulence, focusing on the parameter regime with ? ~ 1, where ? is the ratio of gas to magnetic pressure. We use the simulation results to calibrate analytical expressions for test particle velocity-space diffusion coefficients and provide simple fits that can be used in other work. The test particle velocity diffusion in our simulations is due to a combination of two processes: interactions between particles and magnetic compressions in the turbulence (as in linear transit-time damping; TTD) and what we refer to as Fermi Type-B (FTB) interactions, in which charged particles moving on field lines may be thought of as beads sliding along moving wires. We show that test particle heating rates are consistent with a TTD resonance that is broadened according to a decorrelation prescription that is Gaussian in time (but inconsistent with Lorentzian broadening due to an exponential decorrelation function, a prescription widely used in the literature). TTD dominates the heating for vs Gt vA (e.g., electrons), where vs is the thermal speed of species s and vA is the Alfvén speed, while FTB dominates for vs Lt vA (e.g., minor ions). Proton heating rates for ? ~ 1 are comparable to the turbulent cascade rate. Finally, we show that velocity diffusion of collisionless, large gyrofrequency particles due to large-scale MHD turbulence does not produce a power-law distribution function.
Nonlinear evolution of the MHD Kelvin-Helmholtz instability in a compressible plasma
S. H. Lai; L. H. Lyu
2006-01-01
Kelvin-Helmholtz (K-H) instability at a magnetohydrodynamic (MHD) tangential discontinuity (TD) is studied by means of two-dimensional MHD simulation. The TD is of finite thickness with both magnetic shear and velocity shear across the TD. Our simulation results indicate that the nonlinear evolution of MHD surface waves at the TD depends on the fast-mode Mach numbers of the plasma flows on
MHD MELT CONTROL SYSTEMS FOR HIGH-POWER BEAM WELDING OF METALS
V. V. Avilov; G. Ambrosy; P. Berger
Introduction. One of the major advantages of high-power laser as well as electron beam welding is its tremendous penetration. The width of the penetration pattern is extremely narrow with a depth-to-width ratio up to 20:1 for laser beam welding and much more for electron beam welding. The weld pool and the heat affected zone are much smaller than those of
Perfect magnetohydrodynamics as a field theory
Bekenstein, Jacob D.; Betschart, Gerold [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)
2006-10-15
We propose the generally covariant action for the theory of a self-coupled complex scalar field and electromagnetism which by virtue of constraints is equivalent, in the regime of long wavelengths, to perfect magnetohydrodynamics (MHD). We recover from it the Euler equation with Lorentz force, and the thermodynamic relations for a prefect fluid. The equation of state of the latter is related to the scalar field's self potential. We introduce 1+3 notation to elucidate the relation between MHD and field variables. In our approach the requirement that the scalar field be single valued leads to the quantization of a certain circulation in steps of ({Dirac_h}/2{pi}); this feature leads, in the classical limit, to the conservation of that circulation. The circulation is identical to that in Oron's generalization of Kelvin's circulation theorem to perfect MHD; we here characterize the new conserved helicity associated with it. We also demonstrate the existence for MHD of two Bernoulli-like theorems for each spacetime symmetry of the flow and geometry; one of these is pertinent to suitably defined potential flow. We exhibit the conserved quantities explicitly in the case that two symmetries are simultaneously present, and give examples. Also in this case we exhibit a new conserved MHD circulation distinct from Oron's, and provide an example.
Perfect magnetohydrodynamics as a field theory
Jacob D. Bekenstein; Gerold Betschart
2006-10-16
We propose the generally covariant action for the theory of a self-coupled complex scalar field and electromagnetism which by virtue of constraints is equivalent, in the regime of long wavelengths, to perfect magnetohydrodynamics (MHD). We recover from it the Euler equation with Lorentz force, and the thermodynamic relations for a prefect fluid. The equation of state of the latter is related to the scalar field's self potential. We introduce 1+3 notation to elucidate the relation between MHD and field variables. In our approach the requirement that the scalar field be single valued leads to the quantization of a certain circulation in steps of $\\hbar$; this feature leads, in the classical limit, to the conservation of that circulation. The circulation is identical to that in Oron's generalization of Kelvin's circulation theorem to perfect MHD; we here characterize the new conserved helicity associated with it. We also demonstrate the existence for MHD of two Bernoulli-like theorems for each spacetime symmetry of the flow and geometry; one of these is pertinent to suitably defined potential flow. We exhibit the conserved quantities explicitly in the case that two symmetries are simultaneously present, and give examples. Also in this case we exhibit a new conserved MHD circulation distinct from Oron's, and provide an example.
Analysis of Magnetohydrodynamic Flow in Microfluidics
NASA Astrophysics Data System (ADS)
Panta, Yogendra; Lin, Wei
2009-11-01
Over the last three decades, numerical and experimental fluid dynamic studies have been well documented for optimization of device performance in general fluid dynamics, prediction and analysis of physiological flows, fluid-structure interactions in biological systems, and effectiveness of drug delivery systems in lab on chip devices. Magnetohydrodynamics (MHD) is a proven and a routinely used technology not only in various industries to heat, pump, stir and levitate fluids but also an innovative potential for making remarkable biosensors. Two typical pilot projects to test, analyze and optimize the MHD effects were designed. Microfluidics channels coupled with MHD in various shapes were fabricated from a thin brass sheet sandwiched between two polycarbonate sheets in which two platinum electrodes were patterned on the channel walls. Ionic solution colored with dye was introduced in the channel to visualize the fluid flow with or without the MHD. The induction and driving of fluid motion in the channel was accomplished by placing magnetic field normal to the applied electric field in order to induce Lorentz forces in the fluid contained in the channel. Experimental data and numerical results were obtained in a good agreement. Flow velocities were obtained linearly increasing with the higher magnetic flux densities. Future work will be focused on the development of MHD biosensors for chemical biology applications.
Method for manufacturing magnetohydrodynamic electrodes
Killpatrick, Don H. (Orland Park, IL); Thresh, Henry R. (Palos Heights, IL)
1982-01-01
A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator comprising the steps of preparing a billet having a core 10 of a first metal, a tubular sleeve 12 of a second metal, and an outer sheath 14, 16, 18 of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket 14. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MDH channel frame. The method forms a bond between the first metal of the core 10 and the second metal of the sleeve 12 strong enough to withstand a hot and corrosive environment.
Petrick, Michael (Joliet, IL); Pierson, Edward S. (Chicago, IL); Schreiner, Felix (Mokena, IL)
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.
J. W. S. Blokland; R. Keppens; J. P. Goedbloed
2007-03-22
We present a detailed study of localised magnetohydrodynamical (MHD) instabilities occuring in two--dimensional magnetized accretion disks. We model axisymmetric MHD disk tori, and solve the equations governing a two--dimensional magnetized accretion disk equilibrium and linear wave modes about this equilibrium. We show the existence of novel MHD instabilities in these two--dimensional equilibria which do not occur in an accretion disk in the cylindrical limit. The disk equilibria are numerically computed by the FINESSE code. The stability of accretion disks is investigated analytically as well as numerically. We use the PHOENIX code to compute all the waves and instabilities accessible to the computed disk equilibrium. We concentrate on strongly magnetized disks and sub--Keplerian rotation in a large part of the disk. These disk equilibria show that the thermal pressure of the disk can only decrease outwards if there is a strong gravitational potential. Our theoretical stability analysis shows that convective continuum instabilities can only appear if the density contours coincide with the poloidal magnetic flux contours. Our numerical results confirm and complement this theoretical analysis. Furthermore, these results show that the influence of gravity can either be stabilizing or destabilizing on this new kind of MHD instability. In the likely case of a non--constant density, the height of the disk should exceed a threshold before this type of instability can play a role. This localised MHD instability provides an ideal, linear route to MHD turbulence in strongly magnetized accretion disk tori.
Broken Symmetry and Coherent Structure in MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2007-01-01
Absolute equilibrium ensemble theory for ideal homogeneous magnetohydrodynamic (MHD) turbulence is fairly well developed. Theory and Simulation indicate that ideal MHD turbulence non-ergodic and contains coherent structure. The question of applicability real (i.e., dissipative) MHD turbulence is examined. Results from several very long time numerical simulations on a 64(exp 3) grid are presented. It is seen that coherent structure begins to form before decay dominates over nonlinearity. The connection with inverse spectral cascades and selective decay will also be discussed.
Effect of line-tying on the radiative MHD stability of coronal plasmas with radial pressure profile
An, C.
1984-09-01
We have studied the effects of photospheric line-tying on the localized radiative magnetohydrodynamic (MHD) modes of compressible coronal plasmas. We used a simple trial function to represent the effect of line-tying.
MHD technology transfer, integration, and review committee
NASA Astrophysics Data System (ADS)
1990-05-01
As part of Task 8 of the magnetohydrodynamic (MHD) Integrated Topping Cycle (ITC) project, TRW was given the responsibility to organize, charter and co-chair, with the Department of Energy (DOE), an MHD Technology Transfer, Integration and Review Committee (TTIRC). The TTIRC consists of an Executive Committee (EC) which acts as the governing body, and a General Committee (GC), also referred to as the main or full committee, consisting of representatives from the various POC contractors, participating universities and national laboratories, utilities, equipment suppliers, and other potential MHD users or investors. The purpose of the TTIRC is to: (1) review all Proof-of-Concept (POC) projects and schedules in the national MHD program; to assess their compatibility with each other and the first commercial MHD retrofit plant; (2) establish and implement technology transfer formats for users of this technology; (3) identify interfaces, issues, and funding structures directly impacting the success of the commercial retrofit; (4) investigate and identify the manner in which, and by whom, the above should be resolved; and (5) investigate and assess other participation (foreign and domestic) in the U.S. MHD Program. There are seven sections: introduction; Executive Committee and General Committee activity; Committee activities related to technology transfer; ongoing POC integration activities being performed under the auspices of the Executive Committee; recommendations passed on to the DOE by the Executive Committee; Planned activities for the next six months.
Solar Flares: Magnetohydrodynamic Processes
NASA Astrophysics Data System (ADS)
Shibata, Kazunari; Magara, Tetsuya
2011-12-01
This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD) processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 10^32 erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence), local enhancement of electric current in the corona (formation of a current sheet), and rapid dissipation of electric current (magnetic reconnection) that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely), while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.
Criteria for Scaled Laboratory Simulations of Astrophysical MHD Phenomena
D. D. Ryutov; R. P. Drake; B. A. Remington
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
MHD--Developing New Technology to Meet the Energy Crisis
ERIC Educational Resources Information Center
Fitch, Sandra S.
1978-01-01
Magnetohydrodynamics is a technology that could utilize the nation's most abundant fossil fuel and produce electrical energy more efficiently and cleanly than present-day turbines. A national research and development program is ongoing in Butte, Montana at the Montana Energy and MHD Research and Development Institute (MERDI). (Author/RK)
Adam Larios; Edriss S. Titi
2011-04-03
We prove existence, uniqueness, and higher-order global regularity of strong solutions to a particular Voigt-regularization of the three-dimensional inviscid resistive Magnetohydrodynamic (MHD) equations. Specifically, the coupling of a resistive magnetic field to the Euler-Voigt model is introduced to form an inviscid regularization of the inviscid resistive MHD system. The results hold in both the whole space $\
Thermoacoustic power conversion for space power applications
NASA Astrophysics Data System (ADS)
Ward, William C.; Merrigan, Michael A.
1992-01-01
Thermoacoustic engines are a recent class of devices that convert between heat and sound energy without moving parts. When coupled to a suitable transducer, thermoacoustic prime movers can produce electric power with high reliability and efficiency in lightweight packages that feature low vibration levels. This paper begins with an introduction of thermoacoustics and an overview of design and optimization and then considers analytical results for two transducers that also have no moving parts: piezoelectric transduction for a helium-based engine, and magnetohydrodynamic (MHD) transduction in an engine with liquid sodium working fluid.
Numerical model of a two-dimensional, non-plane transient magnetohydrodynamic flow
NASA Technical Reports Server (NTRS)
Han, S. M.; Wu, S. T.; Nakagawa, Y.
1982-01-01
The equations describing two-dimensional three-component magnetohydrodynamic (MHD) transient flows are formulated for a system of spherical coordinates. With the numerical code based on Implicit Continuous Fluid Eulerian (ICE) scheme, MHD flows resulting from a sudden energy release in a stratified medium are examined. Because of the inclusion of out-of-plane components of velocity and magnetic fields, MHD transverse waves are observed in addition to fast, slow and entropy waves. Numerical results for compressible MHD shocks are found in satisfactory agreement with the theoretical predictions.
ANALYTIC APPROXIMATE SEISMOLOGY OF PROPAGATING MAGNETOHYDRODYNAMIC WAVES IN THE SOLAR CORONA
Goossens, M.; Soler, R. [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium); Arregui, I. [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Terradas, J., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)
2012-12-01
Observations show that propagating magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. The technique of MHD seismology uses the wave observations combined with MHD wave theory to indirectly infer physical parameters of the solar atmospheric plasma and magnetic field. Here, we present an analytical seismological inversion scheme for propagating MHD waves. This scheme uses the observational information on wavelengths and damping lengths in a consistent manner, along with observed values of periods or phase velocities, and is based on approximate asymptotic expressions for the theoretical values of wavelengths and damping lengths. The applicability of the inversion scheme is discussed and an example is given.
Properties of mass-loading shocks. II - Magnetohydrodynamics. [of Giacobini-Zinner and Halley comets
NASA Technical Reports Server (NTRS)
Zank, G. P.; Oughton, S.; Neubauer, F. M.; Webb, G. M.
1992-01-01
The one-dimensional magnetohydrodynamics of mass-loading shocks is examined. These shocks, which are distinct from MHD shocks of classical nonreacting fluid dynamics and of combustion theory and which are characterized by the addition of mass within the shock transition, are to be found at comets and, depending upon circumstances, at nonmagnetized and weakly magnetized planets such as Venus and Mars. A completely general mass-loading form of the Hugoniot equation is derived, and some of the most important differences between mass-loading and nonreacting classical MHD shocks are identified. Two new types of MHD shocks are described which have no classical MHD analogues.
Laser production and heating of plasma for MHD application
Jalufka, N.W.
1988-03-01
Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO/sub 2/ laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO/sub 2/ laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO/sub 2/ laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.
Magnetohydrodynamics of Chiral Relativistic Fluids
Alexey Boyarsky; Jurg Frohlich; Oleg Ruchayskiy
2015-04-19
We study the dynamics of a plasma of charged relativistic fermions at very high temperature $T\\gg m$, where $m$ is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magneto-hydrodynamical description of the evolution of such a plasma. We show that, as compared to conventional MHD for a plasma of non-relativistic particles, the hydrodynamical description of the relativistic plasma involves new degrees of freedom described by a pseudo-scalar field originating in a local asymmetry in the densities of left-handed and right-handed fermions. This field can be interpreted as an effective axion field. Taking into account the chiral anomaly we present dynamical equations for the evolution of this field, as well as of other fields appearing in the MHD description of the plasma. Due to its non-linear coupling to helical magnetic fields, the axion field significantly affects the dynamics of a magnetized plasma and can give rise to a novel type of inverse cascade.
Particle Acceleration by MHD Turbulence
Jungyeon Cho; A. Lazarian
2005-10-21
Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of particle acceleration. We make use of the recently established scaling of slow and fast MHD modes in strong and weak MHD turbulence to provide a systematic study of particle acceleration in magnetic pressure (low-$\\beta$) and gaseous pressure (high-$\\beta$) dominated plasmas. We consider the acceleration by large scale compressions in both slow and fast particle diffusion limits. We compare the results with the acceleration rate that arises from resonance scattering and Transit-Time Damping (TTD). We establish that fast modes accelerate particles more efficiently than slow modes. We find that particle acceleration by pitch-angle scattering and TTD dominates acceleration by slow or fast modes when the spatial diffusion rate is small. When the rate of spatial diffusion of particles is high, we establish an enhancement of the efficiency of particle acceleration by slow and fast modes in weak turbulence. We show that highly supersonic turbulence is an efficient agent for particle acceleration. We find that even incompressible turbulence can accelerate particles on the scales comparable with the particle mean free path.
Ramrus, A.
1986-02-01
Objective of the study was to create conceptual designs of high voltage pulsers capable of simulating two types of electromagnetic pulses (EMPs) caused by a high-altitude nuclear burst; the slow rise time magnetohydrodynamic (MHD-EMP) and the fast rise time high-altitude EMP (HEMP). The pulser design was directed towards facilities capable of performing EMP vulnerability testing of components used in the national electric power system.
Theory of magnetohydrodynamic instabilities excited by energetic particles in tokamaks
Chen, L. (Department of Physics, University of California, Irvine, California 92717-4575 (United States))
1994-07-20
The resonant excitations of high-n magnetohydrodynamic (MHD) instabilities by the energetic ions/alpha particles in tokamaks are theoretically analyzed. Here, n is the toroidal mode number. Since, typically, the MHD modes consist of two-scale structures; one singular ( inertial'') region and one regular (ideal) region, the energetic particle contributions in the singular region are suppressed by the finite-size orbits. Analytical dispersion relations can then be derived via the asymptotic matching analysis. The dispersion relations have the generic form of the fishbone'' dispersion relation and demonstrate, in particular, the existence of two types of modes; that is, the MHD gap mode and the energetic-particle continuum mode. Specific expressions are given for both the kinetic ballooning modes (KBM) and the toroidal Alfven modes (TAM). It is suggested that the stability property may be qualitatively regarded as the hybrid'' of conventional MHD tokamaks and field reversed ion rings. [copyright]American Institute of Physics
On the question of hysteresis in Hall magnetohydrodynamic reconnection
Sullivan, Brian P.; Bhattacharjee, A.; Huang Yimin [Center for Integrated Computation and Analysis of Reconnection and Turbulence, University of New Hampshire, Space Science Center, Durham, New Hampshire 03824 (United States)
2010-11-15
Controversy has been raised regarding the cause of hysteresis, or bistability, of solutions to the equations that govern the geometry of the reconnection region in Hall magnetohydrodynamic (MHD) systems. This brief communication presents a comparison of the frameworks within which this controversy has arisen and illustrates that the Hall MHD hysteresis originally discovered numerically by Cassak et al. [Phys. Rev. Lett. 95, 235002 (2005)] is a different phenomenon from that recently reported by Zocco et al. [Phys. Plasmas 16, 110703 (2009)] on the basis of analysis and simulations in electron MHD with finite electron inertia. We demonstrate that the analytic prediction of hysteresis in EMHD does not describe or explain the hysteresis originally reported in Hall MHD, which is shown to persist even in the absence of electron inertia.
Nearly incompressible fluids. II: Magnetohydrodynamics, turbulence, and waves
NASA Astrophysics Data System (ADS)
Zank, G. P.; Matthaeus, W. H.
1993-01-01
The theory of nearly incompressible (NI) fluid dynamics developed previously for hydrodynamics is extended to magnetohydrodynamics (MHD). On the basis of a singular expansion technique, modified systems of fluid equations are derived for which the effects of compressibility are admitted only weakly in terms of the different possible incompressible solutions (thus ``nearly incompressible MHD''). NI MHD represents the interface between the compressible and incompressible magnetofluid descriptions in the subsonic regime. The theory developed here does not hold in the presence of very large thermal, gravitational, or field gradients. It is found that there exist three distinct NI descriptions corresponding to each of the three possible plasma beta (? ? the ratio of thermal to magnetic pressure) regimes (??1, ?1, ??1). In the ??1 regime, the compressible MHD description converges in the low Mach number limit to the equations of classical incompressible three-dimensional (3-D) MHD. However, for the remaining plasma beta regimes, the imposition of a large dc magnetic field forces the equations of fully compressible 3-D MHD to converge to the equations of 2-D incompressible MHD in the low Mach number limit. The ``collapse in dimensionality'' corresponding to the different plasma beta regimes clarifies the distinction between the 3-D and 2-D incompressible MHD descriptions (and also that of 21/2-D incompressible MHD). The collapse in dimensionality that occurs as a result of a decreased plasma beta can carry over to the weakly compressible corrections. For a ?1 plasma, Alfvén waves propagate parallel to the applied magnetic field (reminiscent of reduced MHD), while for a ??1 magnetofluid, quasi-1-D long-wavelength acoustic modes propagate parallel to the applied magnetic field. The detailed theory of weakly compressible corrections to the various incompressible MHD descriptions is presented and the implications for the solar wind emphasized.
NASA Astrophysics Data System (ADS)
Kisiel, T.; Soida, M.
2007-12-01
The rocket technology dates back as far as medieval China. Used initially for entertainment and religious practices over time rockets evolved into weapons and finally into means of transportation. Today, we are nearing the top of the rockets' capabilities. Although, for now they are the only way for us to send anything into space we are becoming more and more aware of the limitations of this technology. It is essential that we invent other means of propelling probes and other interplanetary vehicles through space. The authors had performed a series of magnetohydrodynamic simulations using the University of Chicago's Flash package to find out whether the interactions between the Solar Wind and the conducting ring with the electric current would occur. The MHD simulations gave the results similar to the monte-carlo calculations performed by dr Charles Danforth from the University of Colorado. It is the authors' conclusion that the promising results should encourage further study of the phenomenon and the possibility of using it in practice.
Thermodynamics of magnetohydrodynamic flows with axial symmetry.
Leprovost, N; Dubrulle, B; Chavanis, P-H
2005-03-01
We present strategies based upon optimization principles in the case of the axisymmetric equations of magnetohydrodynamics (MHD). We derive the equilibrium state by using a minimum energy principle under the constraints of the MHD axisymmetric equations. We also propose a numerical algorithm based on a maximum energy dissipation principle to compute in a consistent way the nonlinearly dynamically stable equilibrium states. Then, we develop the statistical mechanics of such flows and recover the same equilibrium states giving a justification of the minimum energy principle. We find that fluctuations obey a Gaussian shape and we make the link between the conservation of the Casimirs on the coarse-grained scale and the process of energy dissipation. We contrast these results with those of two-dimensional hydrodynamical turbulence where the equilibrium state maximizes a H function at fixed energy and circulation and where the fluctuations are nonuniversal. PMID:15903578
Magnetohydrodynamic Modeling of the Jovian Magnetosphere
NASA Technical Reports Server (NTRS)
Walker, Raymond
2005-01-01
Under this grant we have undertaken a series of magnetohydrodynamic (MHD) simulation and data analysis studies to help better understand the configuration and dynamics of Jupiter's magnetosphere. We approached our studies of Jupiter's magnetosphere in two ways. First we carried out a number of studies using our existing MHD code. We carried out simulation studies of Jupiter s magnetospheric boundaries and their dependence on solar wind parameters, we studied the current systems which give the Jovian magnetosphere its unique configuration and we modeled the dynamics of Jupiter s magnetosphere following a northward turning of the interplanetary magnetic field (IMF). Second we worked to develop a new simulation code for studies of outer planet magnetospheres.
Magnetohydrodynamic modeling of the solar corona
NASA Technical Reports Server (NTRS)
Mikic, Zoran
1990-01-01
The ideal and resistive magnetohydrodynamic (MHD) model is used to examine the dynamics and structure of the solar corona. When the coronal magnetic field is deformed by photospheric flow it can evolve to states that become unstable to ideal MHD modes. The nonlinear evolution of these instabilities can lead to the generation of current sheets, field line reconnection, and energy release. The disruption of an arcade field and the kinking of coronal loops is described. The braiding of the large-scale coronal field by convective photospheric motions develops fine-scale structure in the magnetic field and leads to the development of intense current filaments. The resistive dissipation of these currents can provide an efficient coronal heating mechanism.
Numerical Methods for Radiation Magnetohydrodynamics in Astrophysics
Klein, R I; Stone, J M
2007-11-20
We describe numerical methods for solving the equations of radiation magnetohydrodynamics (MHD) for astrophysical fluid flow. Such methods are essential for the investigation of the time-dependent and multidimensional dynamics of a variety of astrophysical systems, although our particular interest is motivated by problems in star formation. Over the past few years, the authors have been members of two parallel code development efforts, and this review reflects that organization. In particular, we discuss numerical methods for MHD as implemented in the Athena code, and numerical methods for radiation hydrodynamics as implemented in the Orion code. We discuss the challenges introduced by the use of adaptive mesh refinement in both codes, as well as the most promising directions for future developments.
Magnetohydrodynamic propulsion using on-board sources
NASA Astrophysics Data System (ADS)
Martin, James A.
1998-01-01
Magnetohydrodynamics is considered to extract power from flow and to inset power into flow at different points in propulsion systems that might be useful for advanced Earth-to-orbit vehicles. No beamed power is considered, and so the power is all generated from on-board sources. An ideal analysis is used as the first step toward deciding which concepts to examine further. The airbreathing engine concept that uses magnetohydrodynamics to replace the rotating machinery in a turbojet engine provides the most attractive results.
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, and toroidal beta. A proper accounting of energetic ion loss is therefore important for accurate analysis of power balance and transport in plasmas exhibiting MHD-induced energetic ion loss.
Linear wave propagation in relativistic magnetohydrodynamics
R. Keppens; Z. Meliani
2008-10-14
The properties of linear Alfv\\'en, slow, and fast magnetoacoustic waves for uniform plasmas in relativistic magnetohydrodynamics (MHD) are discussed, augmenting the well-known expressions for their phase speeds with knowledge on the group speed. A 3+1 formalism is purposely adopted to make direct comparison with the Newtonian MHD limits easier and to stress the graphical representation of their anisotropic linear wave properties using the phase and group speed diagrams. By drawing these for both the fluid rest frame and for a laboratory Lorentzian frame which sees the plasma move with a three-velocity having an arbitrary orientation with respect to the magnetic field, a graphical view of the relativistic aberration effects is obtained for all three MHD wave families. Moreover, it is confirmed that the classical Huygens construction relates the phase and group speed diagram in the usual way, even for the lab frame viewpoint. Since the group speed diagrams correspond to exact solutions for initial conditions corresponding to a localized point perturbation, their formulae and geometrical construction can serve to benchmark current high-resolution algorithms for numerical relativistic MHD.
Fusion Engineering and Design 81 (2006) 549553 Numerical analysis of MHD flow and heat transfer in a
Abdou, Mohamed
2006-01-01
Fusion Engineering and Design 81 (2006) 549553 Numerical analysis of MHD flow and heat transfer January 2006 Abstract MHD flow and heat transfer have been analyzed for a front poloidal channel blanket; Magnetohydrodynamics; Heat transfer 1. Introduction Using flow channel inserts (FCIs) made
Magnetohydrodynamic waves and coronal seismology: an overview of recent results.
De Moortel, Ineke; Nakariakov, Valery M
2012-07-13
Recent observations have revealed that magnetohydrodynamic (MHD) waves and oscillations are ubiquitous in the solar atmosphere, with a wide range of periods. We give a brief review of some aspects of MHD waves and coronal seismology that have recently been the focus of intense debate or are newly emerging. In particular, we focus on four topics: (i) the current controversy surrounding propagating intensity perturbations along coronal loops, (ii) the interpretation of propagating transverse loop oscillations, (iii) the ongoing search for coronal (torsional) Alfvén waves, and (iv) the rapidly developing topic of quasi-periodic pulsations in solar flares. PMID:22665899
Energy of eigenmodes in magnetohydrodynamic flows of ideal fluids
Khalzov, I. V.; Smolyakov, A. I. [University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan, S7N5E2 (Canada); Russian Research Center 'Kurchatov Institute', 1 Kurchatov Sq., Moscow, 123182 (Russian Federation); Ilgisonis, V. I. [Russian Research Center 'Kurchatov Institute', 1 Kurchatov Sq., Moscow, 123182 (Russian Federation)
2008-05-15
Energy of eigenmodes in magnetohydrodynamic (MHD) flows of ideal fluids is studied analytically. It is shown that the energy of unstable modes is zero, while the energy of stable oscillatory modes (waves) can assume both positive and negative values. Negative energy waves always correspond to eigenmodes with a finite component of the wave-vector along the flow. Coupling of negative and positive energy waves is shown to be a universal mechanism of MHD instabilities in flowing media. As an example, the energy of eigenmodes of magnetorotational instability is calculated.
NASA Technical Reports Server (NTRS)
Montgomery, David
1988-01-01
Three areas of study in MHD turbulence are considered. These are the turbulent relaxation of the toroidal Z pinch, density fluctuations in MHD fluids, and MHD cellular automata. A Boolean computer game that updates a cellular representation in parallel and that has macroscopic averages converging to solutions of the two-dimensional MHD equations is discussed.
NASA Technical Reports Server (NTRS)
Smith, M.; Nichols, L. D.; Seikel, G. R.
1974-01-01
Performance and power costs of H2-O2 combustion powered steam-MHD central power systems are estimated. Hydrogen gas is assumed to be transmitted by pipe from a remote coal gasifier into the city and converted to electricity in a steam MHD plant having an integral gaseous oxygen plant. These steam MHD systems appear to offer an attractive alternative to both in-city clean fueled conventional steam power plants and to remote coal fired power plants with underground electric transmission into the city. Status and plans are outlined for an experimental evaluation of H2-O2 combustion-driven MHD power generators at NASA Lewis Research Center.
Magnetic levitation and MHD propulsion
NASA Astrophysics Data System (ADS)
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 ŕ un redémarrage de programmes concernant la lévitation et la propulsion supraconductrices. Différents systčmes supraconducteurs de lévitation et de propulsion seront décrits en examinant plus particuličrement l'aspect électromagnétique. Quelques programmes ŕ travers le monde seront abordés. Les trains ŕ sustentation magnétique pourraient constituer un nouveau mode de transport terrestre ŕ vitesse élevée (500 km/h) pour le 21^e sičcle. Les japonais n'ont cessé de s'intéresser ŕ ce systčme 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 systčmes ŕ lévitation pour le transport aux Etats Unis. La MHD (Magnéto- Hydro-Dynamique) présente des avantages intéressants pour la propulsion navale et un regain d'intéręt apparaît ŕ l'heure actuelle. Le japon se situe lŕ encore ŕ la pointe des développements actuels avec en particulier les premiers essais en rade de Kobe de Yamato I, navire de 260 tonnes, entraîné par MHD.
Consequences of magnetohydrodynamic processes for large scale flow in the magnetosheath
NASA Technical Reports Server (NTRS)
Kivelson, M. G.; Chen, S.-H.; Southwood, D. J.
1994-01-01
The remarkable success with which gas dynamic models characterize the plasma properties in the magnetosheath has to some degree diverted attention from certain inherently magnetohydrodynamic effects that are expected to introduce important modifications. Three recent aspects of magnetosheath observations: a slow mode structure near the subsolar point, flows at speeds in excess of the solar wind speed, and the shape of the internal boundary, i.e., the magnetopause, provide examples of inherently magnetohydrodynamic (MHD) effects.
Prospects for Nuclear Electric Propulsion Using Closed-Cycle Magnetohydrodynamic Energy Conversion
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Bitteker, L. J.; Jones, J. E.
2001-01-01
Nuclear electric propulsion (NEP) has long been recognized as a major enabling technology for scientific and human exploration of the solar system, and it may conceivably form the basis of a cost-effective space transportation system suitable for space commerce. The chief technical obstacles to realizing this vision are the development of efficient, high-power (megawatt-class) electric thrusters and the development of low specific mass (less than 1 kg/kWe) power plants. Furthermore, comprehensive system analyses of multimegawatt class NEP systems are needed in order to critically assess mission capability and cost attributes. This Technical Publication addresses some of these concerns through a systematic examination of multimegawatt space power installations in which a gas-cooled nuclear reactor is used to drive a magnetohydrodynamic (MHD) generator in a closed-loop Brayton cycle. The primary motivation for considering MHD energy conversion is the ability to transfer energy out of a gas that is simply too hot for contact with any solid material. This has several intrinsic advantages including the ability to achieve high thermal efficiency and power density and the ability to reject heat at elevated temperatures. These attributes lead to a reduction in system specific mass below that obtainable with turbine-based systems, which have definite solid temperature limits for reliable operation. Here, the results of a thermodynamic cycle analysis are placed in context with a preliminary system analysis in order to converge on a design space that optimizes performance while remaining clearly within established bounds of engineering feasibility. MHD technology issues are discussed including the conceptual design of a nonequilibrium disk generator and opportunities for exploiting neutron-induced ionization mechanisms as a means of increasing electrical conductivity and enhancing performance and reliability. The results are then used to make a cursory examination of piloted Mars missions during the 2018 opportunity.
Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence
Donato, S.; Servidio, S.; Carbone, V. [Dipartimento di Fisica, Universita della Calabria, I-87036 Cosenza (Italy); Dmitruk, P. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisica de Buenos Aires, CONICET, Buenos Aires (Argentina); Shay, M. A.; Matthaeus, W. H. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Cassak, P. A. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)
2012-09-15
The statistical study of magnetic reconnection events in two-dimensional turbulence has been performed by comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics (HMHD). The analysis reveals that the Hall term plays an important role in turbulence, in which magnetic islands simultaneously reconnect in a complex way. In particular, an increase of the Hall parameter, the ratio of ion skin depth to system size, broadens the distribution of reconnection rates relative to the MHD case. Moreover, in HMHD the local geometry of the reconnection region changes, manifesting bifurcated current sheets and quadrupolar magnetic field structures in analogy to laminar studies, leading locally to faster reconnection processes in this case of reconnection embedded in turbulence. This study supports the idea that the global rate of energy dissipation is controlled by the large scale turbulence, but suggests that the distribution of the reconnection rates within the turbulent system is sensitive to the microphysics at the reconnection sites.
Akira Miura
1997-01-01
For a two-dimensional (2-D) transverse configuration, where the plasma motion occurs in a 2-D plane transverse to the magnetic field, the nonlinear evolution of the magnetohydrodynamic (MHD) KelvinHelmholtz (KH) instability is investigated by means of a 2-D MHD simulation for a convective fast magnetosonic Mach number 0.35, which is defined for the total jump of the flow velocity. The compressibility
Magnetohydrodynamic turbulence in supernova remnants
Nirupam Roy; Somnath Bharadwaj; Prasun Dutta; Jayaram N. Chengalur
2009-07-23
We present estimates of the angular power spectra of the synchrotron radiation intensity fluctuations at 6 and 20 cm for the shell type supernova remnant Cas A and the filled-centre Crab supernova remnant. We find that the intensity fluctuations of both sources have a power law power spectrum with index -3.24 +/- 0.03. This power law power spectrum is consistent with the magnetohydrodynamic turbulence in the synchrotron emitting plasma. For Cas A, there is a break in the power spectrum and the power law index changes from -3.2 to -2.2 at large angular scale. This transition occurs at an angular scale that corresponds to the shell thickness of Cas A. We interpret this as a transition from three dimensional turbulence to two dimensional turbulence on scales that are respectively smaller and larger than the shell thickness.
Magnetohydrodynamic modeling of the solar corona during Whole Sun Month
J. A. Linker; Z. Mikic; D. A. Biesecker; R. J. Forsyth; S. E. Gibson; A. J. Lazarus; A. Lecinski; P. Riley; A. Szabo; B. J. Thompson
1999-01-01
The Whole Sun Month campaign (August 10 to September 8, 1996) brought together a wide range of space-based and ground-based observations of the Sun and the interplanetary medium during solar minimum. The wealth of data collected provides a unique opportunity for testing coronal models. We develop a three-dimensional magnetohydrodynamic (MHD) model of the solar corona (from 1 to 30 solar
MHD turbulence in the intracluster medium
NASA Astrophysics Data System (ADS)
Falceta-Gonçalves, Diego; Kowal, G.; de Gouveia Dal Pino, E.; Santos-Lima, R.; Nakwacki, S.; Lazarian, A.
2015-03-01
In this work we discuss the turbulent evolution of structures in the intracluster medium based on the two fluid approximations: MHD and collisionless plasma under Chew Goldberger Low (CGL) closure. Turbulence excited by galactic motions and gas inflow in intracluster medium will develop in very different ways considering the two fluid approaches. Statistics of density distributions, and velocity and magnetic fields are provided. Compared to the standard MHD case, the instabilities that arise from CGL-MHD models strongly modify the probability distribution functions of the plasma velocity and density, basically increasing their dispersion. Moreover, the spectra of both density and velocity show increased power at small scales, due to the instabilities growth rate that are larger as smaller scales. Finally, in high beta plasmas, i.e. B 2 << P, a fast increase of the magnetic energy density is observed in the CGL-MHD models, faster than the standard MHD turbulent dynamo that operates at timescales ? ~ L/v L . The signatures of the increased power at small scales and the increase of magnetic field intensity from CGL-MHD models could be observed at radio wavelengths. A comparison of the structure function of the synchrotron emission, as well as the statistics of Faraday rotation effects on the synchrotron polarization, for both the MHD and CGL-MHD models is provided.
Attig, R.C. [ed.
1996-10-09
The development of coal-fired magnetohydrodynamic (MHD) power can be viewed as consisting of two parts; the topping cycle and the bottoming cycle. The topping cycle consists of the coal combustor, MHD generator and associated components. The bottoming cycle consists of the heat recovery, steam generation, seed recovery/regeneration, emissions control (gas and particulate), ash handling and deposition, and materials evaluation. The report concentrates on the bottoming cycle, for which much of the technology was developed at the University of Tennessee Space Institute (UTSI). Because of the complexity of the required technology, a number of issues required investigation. Of specific concern regarding the bottoming cycle, was the design of the steam cycle components and emissions control. First, the high combustion temperatures and the use of large quantities of potassium in the MHD combustor results in a difference in the composition of the gases entering the bottoming cycle compared to conventional systems. Secondly, a major goal of the UTSI effort was to use a variety of coals in the MHD system, especially the large reserves of high-sulfur coals available in the United States.
Price, Daniel
2004-01-01
an algorithm for solving the equations of Magnetohydrodynamics (MHD) using the Smoothed Particle Hydrodynamics investigate multidimensional aspects of the algorithm, refining many of the aspects considered in papers I challenges to be overcome in the numerical solution of the MHD equations. Smoothed Particle Hydrodynamics
Price, Daniel
2004-01-01
an algorithm for solving the equations of Magnetohydrodynamics (MHD) using the Smoothed Particle Hydrodynamics investigate multidimensional aspects of the algorithm, refining many of the aspects considered in papers I challenges to be overcome in the numerical solution of the MHD equations. Smoothed Particle Hydrodynamics
Heeter, R F; Fasoli, A; Testa, D; Sharapov, S; Berk, H L; Breizman, B; Gondhalekar, A; Mantsinen, M
2004-03-23
Experiments are conducted on the JET tokamak to assess the diagnostic potential of MHD active and passive spectroscopy, for the plasma bulk and its suprathermal components, using Alfv{acute e}n Eigenmodes (AEs) excited by external antennas and by energetic particles. The measurements of AE frequencies and mode numbers give information on the bulk plasma. Improved equilibrium reconstruction, in particular in terms of radial profiles of density and safety factor, is possible from the comparison between the antenna driven spectrum and that calculated theoretically. Details of the time evolution of the non-monotonic safety factor profile in advanced scenarios can be reconstructed from the frequency of ICRH-driven energetic particle modes. The plasma effective mass can be inferred from the resonant frequency of externally driven AEs in discharges with similar equilibrium profiles. The stability thresholds and the nonlinear development of the instabilities can give clues on energy and spatial distribution of the fast particle population. The presence of unstable AEs provides lower limits in the energy of ICRH generated fast ion tails. Fast ion pressure gradients and their evolution can be inferred from the stability of AEs at different plasma radial positions. Finally, the details of the AE spectrum in the nonlinear stage can be used to obtain information about the fast particle velocity space diffusion.
Chi-kwan Chan; Dimitrios Psaltis; Feryal Ozel
2006-12-27
Accretion disks are three-dimensional, turbulent, often self-gravitating, magnetohydrodynamic flows, which can be modeled in detail with numerical simulations. In this paper, we present a new algorithm that is based on a spectral decomposition method to simulate such flows. Because of the high order of the method, we can solve the induction equation in terms of the magnetic potential and, therefore, ensure trivially that the magnetic fields in the numerical solution are divergence free. The spectral method also suffers minimally from numerical dissipation and allows for an easy implementation of models for sub-grid physics. Both properties make our method ideal for studying MHD turbulent flows such as those found in accretion disks around compact objects. We verify our algorithm with a series of standard tests and use it to show the development of MHD turbulnce in a simulation of an accretion disk. Finally, we study the evolution and saturation of the power spectrum of MHD turbulence driven by the magnetorotational instability.
Heat transfer in slagging MHD radiant boilers
Im, K.H.; Ahluwalia, R.K.; Berry, G.F.
1981-01-01
A combined convection-radiation model is formulated to study heat transfer characteristics of slagging magnetohydrodynamic (MHD) radiant boilers. The model includes the contributions of carbon dioxide, water vapor, potassium atoms, and slag particles to gas radiation. The model also accounts for the presence of slag layer on the wall of the radiant boiler. In order to determine the slag layer dynamics, the mechanism of slag particle deposition by thermophoresis and by fluid turbulence is also investigated. The role of a slag layer in moderating the influence of refractory thickness on heat transfer is illustrated. 14 refs.
An Action Principle for Relativistic MHD
Eric D'Avignon; Philip Morrison; Francesco Pegoraro
2015-02-02
A covariant action principle for ideal relativistic magnetohydrodynamics (MHD) in terms of natural Eulerian field variables is given. This is done by generalizing the covariant Poisson bracket theory of Marsden et al., which uses a noncanonical bracket to effect constrained variations of an action functional. Various implications and extensions of this action principle are also discussed. Two significant by-products of this formalism are the introduction of a new divergence-free 4-vector variable for the magnetic field, and a new Lie-dragged form for the theory.
Grain Acceleration by MHD Turbulence Gyroresonance Mechanism
Yan, H; Yan, Huirong
2003-01-01
We discuss a new mechanism of dust acceleration that acts in turbulent magnetized medium. The magnetohydrodynamic (MHD) turbulence includes both fluid motions and magnetic fluctuations. We show that while the fluid motions bring about grain motions through the drag, the electromagnetic fluctuations, can accelerate grains through resonant interactions. In this paper we discuss grain acceleration by gyroresonance. We consider both incompressible (Alfven) and compressible (fast and slow) MHD modes. We show that fast modes dominate grain acceleration. In magnetically dominated media, they can render supersonic velocities to grains that may shatter grains and enable efficient adsorption of metals. Since the grains are preferentially accelerated with large pitch angles, the supersonic grains get aligned with long axes perpendicular to the magnetic field.
The generation and damping of propagating MHD kink waves in the solar atmosphere
Morton, R. J. [Mathematics and Information Sciences, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Verth, G.; Erdélyi, R. [Solar Physics and Space Plasma Research Centre (SP2RC), The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Hillier, A., E-mail: richard.morton@northumbria.ac.uk, E-mail: g.verth@sheffield.ac.uk, E-mail: robertus@sheffield.ac.uk [Kwasan and Hida Observatories, Kyoto University, 17 Ohmine-cho Kita Kazan, Yamashina-ku, Kyoto City, Kyoto 607-8471 (Japan)
2014-03-20
The source of the non-thermal energy required for the heating of the upper solar atmosphere to temperatures in excess of a million degrees and the acceleration of the solar wind to hundreds of kilometers per second is still unclear. One such mechanism for providing the required energy flux is incompressible torsional Alfvén and kink magnetohydrodynamic (MHD) waves, which are magnetically dominated waves supported by the Sun's pervasive and complex magnetic field. In particular, propagating MHD kink waves have recently been observed to be ubiquitous throughout the solar atmosphere, but, until now, critical details of the transport of the kink wave energy throughout the Sun's atmosphere were lacking. Here, the ubiquity of the waves is exploited for statistical studies in the highly dynamic solar chromosphere. This large-scale investigation allows for the determination of the chromospheric kink wave velocity power spectra, a missing link necessary for determining the energy transport between the photosphere and corona. Crucially, the power spectra contain evidence for horizontal photospheric motions being an important mechanism for kink wave generation in the quiescent Sun. In addition, a comparison with measured coronal power spectra is provided for the first time, revealing frequency-dependent transmission profiles, suggesting that there is enhanced damping of kink waves in the lower corona.
The Generation and Damping of Propagating MHD Kink Waves in the Solar Atmosphere
NASA Astrophysics Data System (ADS)
Morton, R. J.; Verth, G.; Hillier, A.; Erdélyi, R.
2014-03-01
The source of the non-thermal energy required for the heating of the upper solar atmosphere to temperatures in excess of a million degrees and the acceleration of the solar wind to hundreds of kilometers per second is still unclear. One such mechanism for providing the required energy flux is incompressible torsional Alfvén and kink magnetohydrodynamic (MHD) waves, which are magnetically dominated waves supported by the Sun's pervasive and complex magnetic field. In particular, propagating MHD kink waves have recently been observed to be ubiquitous throughout the solar atmosphere, but, until now, critical details of the transport of the kink wave energy throughout the Sun's atmosphere were lacking. Here, the ubiquity of the waves is exploited for statistical studies in the highly dynamic solar chromosphere. This large-scale investigation allows for the determination of the chromospheric kink wave velocity power spectra, a missing link necessary for determining the energy transport between the photosphere and corona. Crucially, the power spectra contain evidence for horizontal photospheric motions being an important mechanism for kink wave generation in the quiescent Sun. In addition, a comparison with measured coronal power spectra is provided for the first time, revealing frequency-dependent transmission profiles, suggesting that there is enhanced damping of kink waves in the lower corona.
Broken ergodicity in two-dimensional homogeneous magnetohydrodynamic turbulence
Shebalin, John V. [Astromaterials Research and Exploration Science Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)
2010-09-15
Two-dimensional (2D) homogeneous magnetohydrodynamic (MHD) turbulence has many of the same qualitative features as three-dimensional (3D) homogeneous MHD turbulence. These features include several ideal (i.e., nondissipative) invariants along with the phenomenon of broken ergodicity (defined as nonergodic behavior over a very long time). Broken ergodicity appears when certain modes act like random variables with mean values that are large compared to their standard deviations, indicating a coherent structure or dynamo. Recently, the origin of broken ergodicity in 3D MHD turbulence that is manifest in the lowest wavenumbers was found. Here, we study the origin of broken ergodicity in 2D MHD turbulence. It will be seen that broken ergodicity in ideal 2D MHD turbulence can be manifest in the lowest wavenumbers of a finite numerical model for certain initial conditions or in the highest wavenumbers for another set of initial conditions. The origins of broken ergodicity in an ideal 2D homogeneous MHD turbulence are found through an eigenanalysis of the covariance matrices of the probability density function and by an examination of the associated entropy functional. When the values of ideal invariants are kept fixed and grid size increases, it will be shown that the energy in a few large modes remains constant, while the energy in any other mode is inversely proportional to grid size. Also, as grid size increases, we find that broken ergodicity becomes manifest at more and more wavenumbers.
Relativistic magnetohydrodynamics in dynamical spacetimes: Numerical methods and tests
Duez, Matthew D.; Liu, Yuk Tung; Shapiro, Stuart L.; Stephens, Branson C. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
2005-07-15
Many problems at the forefront of theoretical astrophysics require the treatment of magnetized fluids in dynamical, strongly curved spacetimes. Such problems include the origin of gamma-ray bursts, magnetic braking of differential rotation in nascent neutron stars arising from stellar core collapse or binary neutron star merger, the formation of jets and magnetized disks around newborn black holes, etc. To model these phenomena, all of which involve both general relativity (GR) and magnetohydrodynamics (MHD), we have developed a GRMHD code capable of evolving MHD fluids in dynamical spacetimes. Our code solves the Einstein-Maxwell-MHD system of coupled equations in axisymmetry and in full 3+1 dimensions. We evolve the metric by integrating the Baumgarte-Shapiro-Shibata-Nakamura equations, and use a conservative, shock-capturing scheme to evolve the MHD equations. Our code gives accurate results in standard MHD code-test problems, including magnetized shocks and magnetized Bondi flow. To test our code's ability to evolve the MHD equations in a dynamical spacetime, we study the perturbations of a homogeneous, magnetized fluid excited by a gravitational plane wave, and we find good agreement between the analytic and numerical solutions.
Energetic particle effects on global magnetohydrodynamic modes
Cheng, C.Z. (Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (USA))
1990-06-01
The effects of energetic particles on magnetohydrodynamic (MHD) type modes are studied using analytical theories and the nonvariational kinetic-MHD stability code (NOVA-K) ({ital Workshop} {ital on} {ital Theory} {ital of} {ital Fusion} {ital Plasmas}, (Societa Italiana di Fisica, Bologna, 1987), p. 185). In particular, 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 are addressed. Analytical theories are presented to help explain the NOVAresults. For energetic trapped particles generated by neutral beam injection or ion cyclotron resonant heating, a stability window for the {ital n}=1 internal kink mode in the hot particle beta space exists even in the absence of core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to resonantly excite instability of the {ital 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.
Imbalanced relativistic force-free magnetohydrodynamic turbulence
Cho, Jungyeon [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Lazarian, A., E-mail: jcho@cnu.ac.kr [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)
2014-01-01
When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfvénic MHD turbulence in the relativistic limit can be described by interactions of counter-traveling wave packets. In this paper, we numerically study strong imbalanced MHD turbulence in such environments. Here, imbalanced turbulence means the waves traveling in one direction (dominant waves) have higher amplitudes than the opposite-traveling waves (sub-dominant waves). We find that (1) spectrum of the dominant waves is steeper than that of sub-dominant waves, (2) the anisotropy of the dominant waves is weaker than that of sub-dominant waves, and (3) the dependence of the ratio of magnetic energy densities of dominant and sub-dominant waves on the ratio of energy injection rates is steeper than quadratic (i.e., b{sub +}{sup 2}/b{sub ?}{sup 2}?(?{sub +}/?{sub ?}){sup n} with n > 2). These results are consistent with those obtained for imbalanced non-relativistic Alfvénic turbulence. This corresponds well to the earlier reported similarity of the relativistic and non-relativistic balanced magnetic turbulence.
Global invariants in ideal magnetohydrodynamic turbulence
Shebalin, John V. [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)] [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)
2013-10-15
Magnetohydrodynamic (MHD) turbulence is an important though incompletely understood factor affecting the dynamics of many astrophysical, geophysical, and technological plasmas. As an approximation, viscosity and resistivity may be ignored, and ideal MHD turbulence may be investigated by statistical methods. Incompressibility is also assumed and finite Fourier series are used to represent the turbulent velocity and magnetic field. The resulting model dynamical system consists of a set of independent Fourier coefficients that form a canonical ensemble described by a Gaussian probability density function (PDF). This PDF is similar in form to that of Boltzmann, except that its argument may contain not just the energy multiplied by an inverse temperature, but also two other invariant integrals, the cross helicity and magnetic helicity, each multiplied by its own inverse temperature. However, the cross and magnetic helicities, as usually defined, are not invariant in the presence of overall rotation or a mean magnetic field, respectively. Although the generalized form of the magnetic helicity is known, a generalized cross helicity may also be found, by adding terms that are linear in the mean magnetic field and angular rotation vectors, respectively. These general forms are invariant even in the presence of overall rotation and a mean magnetic field. We derive these general forms, explore their properties, examine how they extend the statistical theory of ideal MHD turbulence, and discuss how our results may be affected by dissipation and forcing.
Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary Nebulae
K. H. Tsui
2008-03-04
Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. These configurations are described by time self-similar dynamics, where space and time dependences of each physical variable are in separable form. Axisymmetric toroidal MHD plasma configuration is solved under the gravitational field of a central star of mass $M$. With an azimuthal magnetic field, this self-similar MHD model provides an equatorial structure in the form of an axisymmetric torus with nested and closed toroidal magnetic field lines. In the absence of an azimuthal magnetic field, this formulation models the basic features of bipolar planetary nebulae. The evolution function, which accounts for the time evolution of the system, has a bounded and an unbounded evolution track governed respectively by a negative and positive energy density constant $H$.
Magnetohydrodynamics in full general relativity: Formulation and tests
Masaru Shibata; Yu-ichiou Sekiguchi
2005-07-16
A new implementation for magnetohydrodynamics (MHD) simulations in full general relativity (involving dynamical spacetimes) is presented. In our implementation, Einstein's evolution equations are evolved by a BSSN formalism, MHD equations by a high-resolution central scheme, and induction equation by a constraint transport method. We perform numerical simulations for standard test problems in relativistic MHD, including special relativistic magnetized shocks, general relativistic magnetized Bondi flow in stationary spacetime, and a longterm evolution for self-gravitating system composed of a neutron star and a magnetized disk in full general relativity. In the final test, we illustrate that our implementation can follow winding-up of the magnetic field lines of magnetized and differentially rotating accretion disks around a compact object until saturation, after which magnetically driven wind and angular momentum transport inside the disk turn on.
Magnetohydrodynamics in full general relativity: Formulation and tests
Shibata, Masaru; Sekiguchi, Yu-ichirou [Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan)
2005-08-15
A new implementation for magnetohydrodynamics (MHD) simulations in full general relativity (involving dynamical spacetimes) is presented. In our implementation, Einstein's evolution equations are evolved by a Baumgarte-Shapiro-Shibata-Nakamura formalism, MHD equations by a high-resolution central scheme, and induction equation by a constraint transport method. We perform numerical simulations for standard test problems in relativistic MHD, including special relativistic magnetized shocks, general relativistic magnetized Bondi flow in stationary spacetime, and a long-term evolution for self-gravitating system composed of a neutron star and a magnetized disk in full general relativity. In the final test, we illustrate that our implementation can follow winding-up of the magnetic field lines of magnetized and differentially rotating accretion disks around a compact object until saturation, after which magnetically driven wind and angular momentum transport inside the disk turn on.
The superconducting MHD-propelled ship YAMATO-1
NASA Technical Reports Server (NTRS)
Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro
1995-01-01
In 1985 the Ship & Ocean Foundation (SOF) created a committee under the chairmanship of Mr. Yohei Sasakawa, Former President of the Ship & Ocean Foundation, and began researches into superconducting magnetohydrodynamic (MHD) ship propulsion. In 1989 SOF set to construction of a experimental ship on the basis of theoretical and experimental researches pursued until then. The experimental ship named YAMATO-1 became the world's first superconducting MHD-propelled ship on her trial runs in June 1992. This paper describes the outline of the YAMATO-1 and sea trial test results.
The superconducting MHD-propelled ship YAMATO-1
NASA Astrophysics Data System (ADS)
Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro
1995-04-01
In 1985 the Ship & Ocean Foundation (SOF) created a committee under the chairmanship of Mr. Yohei Sasakawa, Former President of the Ship & Ocean Foundation, and began researches into superconducting magnetohydrodynamic (MHD) ship propulsion. In 1989 SOF set to construction of a experimental ship on the basis of theoretical and experimental researches pursued until then. The experimental ship named YAMATO-1 became the world's first superconducting MHD-propelled ship on her trial runs in June 1992. This paper describes the outline of the YAMATO-1 and sea trial test results.
An MHD GADGET for cosmological simulations
NASA Astrophysics Data System (ADS)
Dolag, K.; Stasyszyn, F.
2009-10-01
Various radio observations have shown that the hot atmospheres of galaxy clusters are magnetized. However, our understanding of the origin of these magnetic fields, their implications on structure formation and their interplay with the dynamics of the cluster atmosphere, especially in the centres of galaxy clusters, is still very limited. In preparation for the upcoming new generation of radio telescopes (like Expanded Very Large Array, Low Wavelength Array, Low Frequency Array and Square Kilometer Array), a huge effort is being made to learn more about cosmological magnetic fields from the observational perspective. Here we present the implementation of magnetohydrodynamics (MHD) in the cosmological smoothed particle hydrodynamics (SPH) code GADGET. We discuss the details of the implementation and various schemes to suppress numerical instabilities as well as regularization schemes, in the context of cosmological simulations. The performance of the SPH-MHD code is demonstrated in various one- and two-dimensional test problems, which we performed with a fully, three-dimensional set-up to test the code under realistic circumstances. Comparing solutions obtained using ATHENA, we find excellent agreement with our SPH-MHD implementation. Finally, we apply our SPH-MHD implementation to galaxy cluster formation within a large, cosmological box. Performing a resolution study we demonstrate the robustness of the predicted shape of the magnetic field profiles in galaxy clusters, which is in good agreement with previous studies.
Magnetohydrodynamic cellular automata
NASA Technical Reports Server (NTRS)
Montgomery, David; Doolen, Gary D.
1987-01-01
A generalization of the hexagonal lattice gas model of Frisch, Hasslacher and Pomeau is shown to lead to two-dimensional magnetohydrodynamics. The method relies on the ideal point-wise conservation law for vector potential.
Nonlinear evolution of the MHD Kelvin-Helmholtz instability in a compressible plasma
S. H. Lai; L. H. Lyu
2006-01-01
Received 6 August 2004; revised 3 November 2005; accepted 9 November 2005; published 14 January 2006. (1) Kelvin-Helmholtz (K-H) instability at a magnetohydrodynamic (MHD) tangential discontinuity (TD) is studied by means of two-dimensional MHD simulation. The TD is of finite thickness with both magnetic shear and velocity shear across the TD. Our simulation results indicate that the nonlinear evolution of
Nonlinear Evolution of the MHD Kelvin-Helmholtz Instability in a Compressible Flow
T. Jones; A. Frank; D. Ryu
1994-01-01
In this poster, we present multidimensional simulations of the magnetohydrodynamic (MHD) Kelvin-Helmholtz instability in a compressible ideal flow. Simulations have been performed with a multidimensional MHD code, based on the Total Variation Diminishing scheme (Harten 1983) which is a second-order-accurate extension of the Roe-type upwind scheme. The one-dimensional version of the code utilizes an approximate Riemann solver described in Brio
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.
Joachim Birn; Michael Hesse
1994-01-01
The acceleration of protons in a dynamically evolving magnetotail is investigated by tracing particles in the fields obtained from a three-dimensional resistive magnetohydrodynamic (MHD) simulation. The MHD simulation, representing plasmoid formation and ejection through a near-Earth reconnection process, leads to cross-tail electric fields of up to approximately 4 mV\\/m with integrated voltages across the tail of up to approximately 200
Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Xu, Kun
1998-01-01
A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.
On the Existence and Non-uniqueness of Solutions of Riemann Problems in Ideal Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Takahashi, K.; Yamada, S.
2014-09-01
We have built a new exact Riemann solver for ideal magnetohydrodynamics (MHD) that can handle all types of the non-regular waves, such as intermediate shocks and switch-on/off waves. This code can find all the exact solutions for a given MHD Riemann problem. Using the solver, we found that there are uncountably many non-regular solutions for the Brio & Wu problem, which is one of the best-known MHD Riemann problems as it is used as a test problem for numerical codes. This result has cast a question on the numerical MHD simulations: Why do most of the numerical MHD codes always produce a typical non-regular solution which consists of a compound wave?
NASA Astrophysics Data System (ADS)
Guo, Xiaocheng
2015-06-01
By revisiting the derivation of the previously developed HLLC Riemann solver for magneto-hydrodynamics (MHD), the paper presents an extended HLLC Riemann solver specifically designed for the MHD system in which the magnetic field can be decomposed into a strong internal magnetic field and an external component. The derived HLLC Riemann solver satisfies the conservation laws. The numerical tests show that the extended solver deals with the global MHD simulation of the Earth's magnetosphere well, and maintains high numerical resolution. It recovers the previously developed HLLC Riemann solver for the MHD as long as the internal field is set to zero. Thus, it is backward compatible with the previous HLLC solver, and suitable for the MHD simulations no matter whether a strong internal magnetic field is included or not.
Battery storage concept for magnetohydrodynamic generator systems
J. R. Goldstein; H. Branover; A. El-Boher
1989-01-01
The authors describe a battery storage and voltage conversion concept appropriate to liquid metal magnetohydrodynamic (LMMHD) generator systems. LMMHD generators in principle provide a low-voltage, very-high-amperage direct current power output, and hence there is a need to develop a simple, efficient and cost-effective power conditioning system to handle this output power. Various approaches and their drawbacks are discussed. These include
Wave turbulence in magnetohydrodynamics
Sebastien Galtier
2012-01-06
This chapter reviews the recent progress made mainly during the last two decades on wave turbulence in magnetized plasmas (MHD, Hall MHD and electron MHD) in the incompressible and compressible cases. The emphasis is made on homogeneous and anisotropic turbulence which usually provides the best theoretical framework to investigate space and laboratory plasmas. The interplanetary medium and the solar atmosphere are presented as two examples of media where anisotropic wave turbulence is relevant. The most important results of wave turbulence are reported and discussed in the context of space and simulated magnetized plasmas. Important issues and possible spurious interpretations are eventually discussed.
Global MHD Simulation of the Inner Accretion Disk in a Pseudo-Newtonian Potential
John F. Hawley; Julian H. Krolik
2000-09-28
We present a detailed three dimensional magnetohydrodynamic (MHD) simulation describing the inner region of a disk accreting onto a black hole. To avoid the technical complications of general relativity, the dynamics are treated in Newtonian fashion using the pseudo-Newtonian Pacz\\'ynski-Wiita potential. The disk evolves due to angular momentum transport which is produced naturally from MHD turbulence generated by the magnetorotational instability. We find that the resulting stress is continuous across the marginally stable orbit, in contradiction with the widely-held assumption that the stress should go to zero there. As a consequence, the specific angular momentum of the matter accreted into the hole is smaller than the specific angular momentum at the marginally stable orbit. The disk exhibits large fluctuations in almost every quantity, both spatially and temporally. In particular, the ratio of stress to pressure (the local analog of the Shakura-Sunyaev $\\alpha$ parameter) exhibits both systematic gradients and large fluctuations; from $\\sim 10^{-2}$ in the disk midplane at large radius, it rises to $\\sim 10$ both at a few gas density scaleheights above the plane at large radius, and near the midplane well inside the plunging region. Driven in part by large-amplitude waves excited near the marginally stable orbit, both the mass accretion rate and the integrated stress exhibit large fluctuations whose Fourier power spectra are smooth "red" power-laws stretching over several orders of magnitude in timescale.
MHD considerations for a self-cooled liquid lithium blanket
Sze, D.K.; Mattas, R.F.; Hull, A.B.; Picologlou, B.F.; Smith, D.L.
1992-03-01
The magnetohydrodynamic (MHD) effects can present a feasibility issue for a self-cooled liquid metal blanket of magnetically confined fusion reactors, especially inboard regime of a tokamak. This pressure drop can be significantly reduced by using insulated wall structure. A self-healing insulating coating has been identified, which will reduce the pressure drop by more than a factor of 10. The future research direction to further quantify the performance of this coating is also outlined.
A Comparative Study of Velocity Statistics of Hydrodynamic and Magnetohydrodynamic Turbulence
Nicholas Hall; G. Kowal; A. Lazarian; Jungyeon Cho
2006-11-15
Turbulence in an incompressible fluid with and without a magnetic field as well as moderately compressible MHD turbulence are compared. For the magnetohydrodynamic (MHD) models the probability distribution functions of the velocity components perpendicular to the external magnetic field are like the incompressible hydrodynamic (HD) model while those parallel to the field have a smaller range of velocities. The probability distribution functions of the transverse velocity increments for the MHD models decline slower than the incompressible HD model. The similarity of incompressible HD and both incompressible and compressible MHD turbulence persists over high order longitudinal structure function scaling exponents measured in the global reference frame as well as for motions perpendicular to the local mean field. In these two frames the longitudinal scaling exponents of both MHD models seem to follow theoretical incompressible HD dissipation structure predictions while the transverse scaling exponents of the incompressible MHD model seem to follow the predictions for incompressible MHD. In the local magnetic system the motions parallel to the local mean field for both MHD models are different from incompressible HD motions. The fields of the MHD simulations are decomposed into Alfvenic, fast, and slow modes and stuided separately. (abridged)
Relativistic radiation magnetohydrodynamics in dynamical spacetimes: Numerical methods and tests
NASA Astrophysics Data System (ADS)
Farris, Brian D.; Li, Tsz Ka; Liu, Yuk Tung; Shapiro, Stuart L.
2008-07-01
Many systems of current interest in relativistic astrophysics require a knowledge of radiative transfer in a magnetized gas flowing in a strongly curved, dynamical spacetime. Such systems include coalescing compact binaries containing neutron stars or white dwarfs, disks around merging black holes, core-collapse supernovae, collapsars, and gamma-ray burst sources. To model these phenomena, all of which involve general relativity, radiation (photon and/or neutrino), and magnetohydrodynamics (MHD), we have developed a general relativistic code capable of evolving MHD fluids and radiation in dynamical spacetimes. Our code solves the coupled Einstein-Maxwell-MHD-radiation system of equations both in axisymmetry and in full 3+1 dimensions. We evolve the metric by integrating the BSSN (Baumgarte-Shapiro-Shibata-Nakamura) equations, and use a conservative, high-resolution shock-capturing scheme to evolve both the MHD and radiation moment equations. In this paper, we implement our scheme for optically thick gases and gray-body opacities. Our code gives accurate results in a suite of tests involving radiating shocks and nonlinear waves propagating in Minkowski spacetime. In addition, to test our codes ability to evolve the relativistic radiation-MHD equations in strong-field dynamical spacetimes, we study thermal Oppenheimer-Snyder collapse to a black hole and find good agreement between analytic and numerical solutions.
NASA Astrophysics Data System (ADS)
Huang, Chia-Lin; Spence, Harlan E.; Singer, Howard J.; Hughes, W. Jeffrey
2010-06-01
To provide critical ULF wave field information for radial diffusion studies in the radiation belts, we quantify ULF wave power (f = 0.5-8.3 mHz) in GOES observations and magnetic field predictions from a global magnetospheric model. A statistical study of 9 years of GOES data reveals the wave local time distribution and power at geosynchronous orbit in field-aligned coordinates as functions of wave frequency, solar wind conditions (Vx, ?Pd and IMF Bz) and geomagnetic activity levels (Kp, Dst and AE). ULF wave power grows monotonically with increasing solar wind Vx, dynamic pressure variations ?Pd and geomagnetic indices in a highly correlated way. During intervals of northward and southward IMF Bz, wave activity concentrates on the dayside and nightside sectors, respectively, due to different wave generation mechanisms in primarily open and closed magnetospheric configurations. Since global magnetospheric models have recently been used to trace particles in radiation belt studies, it is important to quantify the wave predictions of these models at frequencies relevant to electron dynamics (mHz range). Using 27 days of real interplanetary conditions as model inputs, we examine the ULF wave predictions modeled by the Lyon-Fedder-Mobarry magnetohydrodynamic code. The LFM code does well at reproducing, in a statistical sense, the ULF waves observed by GOES. This suggests that the LFM code is capable of modeling variability in the magnetosphere on ULF time scales during typical conditions. The code provides a long-missing wave field model needed to quantify the interaction of radiation belt electrons with realistic, global ULF waves throughout the inner magnetosphere.
Broken Ergodicity in MHD Turbulence in a Spherical Domain
NASA Astrophysics Data System (ADS)
Shebalin, J. V.; Wang, Y.
2011-12-01
Broken ergodicity (BE) occurs in Fourier method numerical simulations of ideal, homogeneous, incompressible magnetohydrodynamic (MHD) turbulence. Although naďve statistical theory predicts that Fourier coefficients of fluid velocity and magnetic field are zero-mean random variables, numerical simulations clearly show that low-wavenumber coefficients have non-zero mean values that can be very large compared to the associated standard deviation. In other words, large-scale coherent structure (i.e., broken ergodicity) in homogeneous MHD turbulence can spontaneously grow out of random initial conditions. Eigenanalysis of the modal covariance matrices in the probability density functions of ideal statistical theory leads to a theoretical explanation of observed BE in homogeneous MHD turbulence. Since dissipation is minimal at the largest scales, BE is also relevant for resistive magnetofluids, as evidenced in numerical simulations. Here, we move beyond model magnetofluids confined by periodic boxes to examine BE in rotating magnetofluids in spherical domains using spherical harmonic expansions along with suitable boundary conditions. We present theoretical results for 3-D and 2-D spherical models and also present computational results from dynamical simulations of 2-D MHD turbulence on a rotating spherical surface. MHD turbulence on a 2-D sphere is affected by Coriolus forces, while MHD turbulence on a 2-D plane is not, so that 2-D spherical models are a useful (and simpler) intermediate stage on the path to understanding the much more complex 3-D spherical case.
Broken Ergodicity in MHD Turbulence in a Spherical Domain
NASA Technical Reports Server (NTRS)
Shebalin, John V.; wang, Yifan
2011-01-01
Broken ergodicity (BE) occurs in Fourier method numerical simulations of ideal, homogeneous, incompressible magnetohydrodynamic (MHD) turbulence. Although naive statistical theory predicts that Fourier coefficients of fluid velocity and magnetic field are zero-mean random variables, numerical simulations clearly show that low-wave-number coefficients have non-zero mean values that can be very large compared to the associated standard deviation. In other words, large-scale coherent structure (i.e., broken ergodicity) in homogeneous MHD turbulence can spontaneously grow out of random initial conditions. Eigenanalysis of the modal covariance matrices in the probability density functions of ideal statistical theory leads to a theoretical explanation of observed BE in homogeneous MHD turbulence. Since dissipation is minimal at the largest scales, BE is also relevant for resistive magnetofluids, as evidenced in numerical simulations. Here, we move beyond model magnetofluids confined by periodic boxes to examine BE in rotating magnetofluids in spherical domains using spherical harmonic expansions along with suitable boundary conditions. We present theoretical results for 3-D and 2-D spherical models and also present computational results from dynamical simulations of 2-D MHD turbulence on a rotating spherical surface. MHD turbulence on a 2-D sphere is affected by Coriolus forces, while MHD turbulence on a 2-D plane is not, so that 2-D spherical models are a useful (and simpler) intermediate stage on the path to understanding the much more complex 3-D spherical case.
Large amplitude MHD waves upstream of the Jovian bow shock
NASA Technical Reports Server (NTRS)
Goldstein, M. L.; Smith, C. W.; Matthaeus, W. H.
1983-01-01
Observations of large amplitude magnetohydrodynamics (MHD) waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 mHz have a direction of minimum variance along the direction of the average magnetic field. The direction of minimum variance of these fluctuations lies at approximately 40 deg. to the magnetic field and is parallel to the radial direction. We argue that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the plasma rest frame. A linear instability analysis is presented which suggests an explanation for many of the observed features of the observations.
Picologlou, B F; Batenin, V M [eds.
1980-07-01
A description of the modifications made to improve the plasma parameters of the U-25B Facility is presented. The oxygen enrichment system was modified to allow oxygen enrichment of up to 50% (by volume) ahead of the preheaters. Optimum design and operating conditions of the seed injection system were defined as a result of experimental investigations. An account of the extensive diagnostic studies performed and a description of the measurement techniques and of the new submillimeter laser interferometer are given. The performance of the MHD generator is analyzed for different operating modes. Studies of fluctuations and nonuniformities, current take-off distributions, local electrical analysis, overall heat transfer history of the MHD channel, and an extensive parametric study of the generator are presented. A detailed account of the complete disassembly and inspection of channel No. 1 after more than 100 hours of operation with the combustor, and of the condition of its various elements is also given.
Gao, Feng; Kreidermacher, Adam; Fritsch, Ingrid; Heyes, Colin D
2013-05-01
Redox magnetohydrodynamics (MHD) is a promising technique for developing new electrochemical-based microfluidic flow devices with unique capabilities, such as easily switching flow direction and adjusting flow speeds and flow patterns as well as avoiding bubble formation. However, a detailed description of all the forces involved and predicting flow patterns in confined geometries is lacking. In addition to redox-MHD, density gradients caused by the redox reactions also play important roles. Flow in these devices with small fluid volumes has mainly been characterized by following microbead motion by optical microscopy either by particle tracking velocimetry (PTV) or by processing the microbead images by particle image velocimetry (PIV) software. This approach has limitations in spatial resolution and dimensionality. Here we use fluorescence correlation spectroscopy (FCS) to quantitatively and accurately measure flow speeds and patterns in the ~5-50 ?m/s range in redox-MHD-based microfluidic devices, from which 3D flow maps are obtained with a spatial resolution down to 2 ?m. The 2 ?m spatial resolution flow speeds map revealed detailed flow profiles during redox-MHD in which the velocity increases linearly from above the electrode and reaches a plateau across the center of the cell. By combining FCS and video-microscopy (with PTV and PIV processing approaches), we are able to quantify a vertical flow of ~10 ?m/s above the electrodes as a result of density gradients caused by the redox reactions and follow convection flow patterns. Overall, combining FCS, PIV, and PTV analysis of redox-MHD is a powerful combination to more thoroughly characterize the underlying forces in these promising microfluidic devices. PMID:23537496
Gao, Feng; Kreidermacher, Adam; Fritsch, Ingrid; Heyes, Colin D.
2013-01-01
Redox magnetohydrodynamics (MHD) is a promising technique for developing new electrochemical-based microfluidic flow devices with unique capabilities, such as easily switching flow direction, adjusting flow speeds and flow patterns as well as avoiding bubble formation. However, a detailed description of all the forces involved and predicting flow patterns in confined geometries is lacking. In addition to redox-MHD, density gradients caused by the redox reactions also play important roles. Flow in these devices with small fluid volumes has mainly been characterized by following microbead motion by optical microscopy either by particle tracking velocimetry (PTV) or by processing the microbead images by particle image velocimetry (PIV) software. This approach has limitations in spatial resolution and dimensionality. Here we use fluorescence correlation spectroscopy (FCS) to quantitatively and accurately measure flow speeds and patterns in the ~5-50 ?m/s range in redox-MHD-based microfluidic devices, from which 3D flow maps are obtained with a spatial resolution down to 2 ?m. The 2 ?m spatial resolution flow speeds map revealed detailed flow profiles during redox-MHD in which the velocity increases linearly from above the electrode, and reaches a plateau across the center of the channel. By combining FCS and video-microscopy (with PTV and PIV processing approaches), we are able to quantify a vertical flow of ~10 ?m/s above the electrodes as a result of density gradients caused by the redox reactions and follow convection flow patterns. Overall, combining FCS, PIV and PTV analysis of redox-MHD is a powerful combination to more thoroughly characterize the underlying forces in these promising microfluidic devices. PMID:23537496
Applying MHD technology to the continuous casting of steel slab
NASA Astrophysics Data System (ADS)
Takeuchi, Eiichi
1995-05-01
The application of magnetohydrodynamics (MHD) in the continuous casting process started with the electromagnetic stirring of the stand pool with a traveling magnetic field. It has now advanced to the electromagnetic stirring of molten steel in the mold and the control of molten steel flow by an in-mold direct current magnetic field brake. These applied MHD techniques are designed to further improve the continuous casting process capability. They improve the surface quality of cast steel by homogenizing the meniscus temperature, stabilizing initial solidification, and cleaning the surface layer. They also improve the internal quality of cast steel by preventing inclusions from penetrating deep into the pool and promoting the flotation of argon bubbles. Applied MHD technology is still advancing in scope and methods in addition to the improvement of conventional continuously cast slab qualities. The continuous casting of bimetallic slab by suppressing mixing in the pool is one example of this progress.
Outline of fast analyzer for MHD equilibrium FAME
NASA Astrophysics Data System (ADS)
Sakata, Shinya; Haginoya, Hirofumi; Tsuruoka, Takuya; Aoyagi, Tetsuo; Saito, Naoyuki; Harada, Hiroo; Tani, Keiji; Watanabe, Hideto
1994-02-01
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.
Picologlou, B F; Batenin, V M
1981-01-01
A description of the main results obtained during Tests No. 6 and 7 at the U-25B Facility using the new channel No. 2 is presented. The purpose of these tests was to operate the MHD generator at its design parameters. Described here are new plasma diagnostic devices: a traversing dual electrical probe for determining distribution of electron concentrations, and a traversing probe that includes a pitot tube for measuring total and static pressure, and a light detector for measuring plasma luminescence. Data are presented on heat flux distribution along the channel, the first data of this type obtained for an MHD facility of such size. Results are given of experimental studies of plasma characteristics, gasdynamic, thermal, and electrical MHD channel performance, and temporal and spatial nonuniformities. Typical modes of operation are analyzed by means of local electrical analyses. Computer models are used to obtain predictions for both localized and overall generator characteristics. These theoretical predictions agree closely with the results of the local analyses, as well as with measurements of the overall gasdynamic and electrical characteristics of the generator.
MHD Kelvin-Helmholtz instability with finite Larmor radius effects and implications for Venus
Ute Amerstorfer; Nikolay Erkaev; Helfried K. Biernat
2008-01-01
In this work, the Kelvin-Helmholtz instability is studied by solving the magnetohydrodynamic (MHD) equations for a compressible plasma. The effect of a finite Larmor radius (FLR) of the ions is included in the equation of motion in the form of the so-called gyroviscosity tensor. A transition layer of finite thickness between two plasmas, across which the plasma properties change, is
MHD coal-fired flow facility. Quarterly technical progress report, July-September 1979
J. B. Dicks; J. N. Chapman; L. W. Crawford
1979-01-01
In this third quarterly report of 1979, the University of Tennessee Space Institute (UTSI) reports on significant activity, project and task status, planned research, testing, and development, and conclusions with respect to the Magnetohydrodynamics (MHD) Coal-Fired Flow Facility (CFFF) and the Research and Development Laboratory. This quarter, work on the CFFF progressed with only minor problems. The weather was generally
The bifurcation analysis of the MHD RankineHugoniot equations for a perfect gas
Heinrich Freistühler; Christian Rohde
2003-01-01
This article provides a complete bifurcation analysis of the RankineHugoniot equations for compressible magnetohydrodynamics (MHD) in the case of a perfect gas. Particular scaling properties of the perfect-gas equation of state are used to reduce the number of bifurcation parameters. The smaller number, together with a novel choice, of these parameters results in a detailed picture of the global situation
The Bifurcation Analysis of the MHD Rankine-Hugoniot Equations for a Perfect Gas
Heinrich Freistuhler; Christian Rohde
This article provides the complete bifurcation analysis of the Rankine- Hugoniot equations for compressible magnetohydrodynamics (MHD) in the case of a perfect gas. Particular scaling properties of the perfect-gas equation of state are used to reduce the number of bifurcation parameters. The smaller number, together with a novel choice, of these parameters results in a detailed picture of the global
The MHD Rankine-Hugoniot jump conditions and the terrestrial bow shock - A statistical comparison
D. Winterhalter; M. G. Kivelson; R. J. Walker; C. T. Russell
1984-01-01
The magnetohydrodynamic (MHD) Rankine-Hugoniot jump conditions are the equations which are most often used in studies regarding the alteration of a magnetized plasma flow during the passage through the earth's bow shock. These equations describe the downstream state of the plasma in terms of the upstream parameters. The present investigation is concerned with a determination of the solar wind conditions
Cooling or Boiling? Cooling Flow Problem and MHD Instabilities in Galaxy Clusters
Tamara Bogdanovic; C. S. Reynolds; S. A. Balbus; I. J. Parrish
2010-01-01
In recent years our understanding of the action of thermal conduction in the atmospheres such as the intercluster matter (ICM) is undergoing a revolution. It has been realized that thermal conduction can lead to magnetohydrodynamic (MHD) instabilities at all radii in the ICM of clusters and in such way affect the evolution of their thermodynamic properties. I will describe findings
Axisymmetric modeling of cometary mass loading on an adaptively refined grid: MHD results
Tamas I. Gombosi; Kenneth G. Powell; Darren L. de Zeeuw
1994-01-01
The first results of an axisymmetric magnetohydrodynamic (MHD) model of the interaction of an expanding cometary atmosphere with the solar wind are presented. The model assumes that far upstream the plasma flow lines are parallel to the magnetic field vector. The effects of mass loading and ion-neutral friction are taken into account by the governing equations, whcih are solved on
Comments on the MHD stability of coronal plasmas with line-tying
C.-H. An
1984-01-01
The effect of line-tying in the photosphere on the magnetohydrodynamic (MHD) stability of coronal loops has been investigated by a number of authors. The author comments on the various boundary conditions, plasma displacement functions, and other assumptions used by a number of investigators. Then he studies kink instabilities in cylindrical plasmas. The results are very different from those of a
Numerical Simulation of Turbulent MHD Flows Using an Iterative PNS Algorithm
NASA Technical Reports Server (NTRS)
Kato, Hiromasa; Tannehill, John C.; Mehta, Unmeel B.
2003-01-01
A new parabolized Navier-Stokes (PNS) algorithm has been developed to efficiently compute magnetohydrodynamic (MHD) flows in the low magnetic Reynolds number regime. In this regime, the electrical conductivity is low and the induced magnetic field is negligible compared to the applied magnetic field. The MHD effects are modeled by introducing source terms into the PNS equation which can then be solved in a very efficient manner. To account for upstream (elliptic) effects, the flowfields are computed using multiple streamwise sweeps with an iterated PNS algorithm. Turbulence has been included by modifying the Baldwin-Lomax turbulence model to account for MHD effects. The new algorithm has been used to compute both laminar and turbulent, supersonic, MHD flows over flat plates and supersonic viscous flows in a rectangular MHD accelerator. The present results are in excellent agreement with previous complete Navier-Stokes calculations.
NASA Technical Reports Server (NTRS)
Kabin, K.; Hansen, K. C.; Gombosi, T. I.; Combi, M. R.; Linde, T. J.; DeZeeuw, D. L.; Groth, C. P. T.; Powell, K. G.; Nagy, A. F.
2000-01-01
Magnetohydrodynamics (MHD) provides an approximate description of a great variety of processes in space physics. Accurate numerical solutions of the MHD equations are still a challenge, but in the past decade a number of robust methods have appeared. Once these techniques made the direct solution of MHD equations feasible, a number of global three-dimensional models were designed and applied to many space physics objects. The range of these objects is truly astonishing, including active galactic nuclei, the heliosphere, the solar corona, and the solar wind interaction with planets, satellites, and comets. Outside the realm of space physics, MHD theory has been applied to such diverse problems as laboratory plasmas and electromagnetic casting of liquid metals. In this paper we present a broad spectrum of models of different phenomena in space science developed in the recent years at the University of Michigan. Although the physical systems addressed by these models are different, they all use the MHD equations as a unifying basis.
On weak and strong magnetohydrodynamic turbulence
Jean Carlos Perez; Stanislav Boldyrev
2007-12-13
Recent numerical and observational studies contain conflicting reports on the spectrum of magnetohydrodynamic turbulence. In an attempt to clarify the issue we investigate anisotropic incompressible magnetohydrodynamic turbulence with a strong guide field $B_0$. We perform numerical simulations of the reduced MHD equations in a special setting that allows us to elucidate the transition between weak and strong turbulent regimes. Denote $k_{\\|}$, $k_\\perp$ characteristic field-parallel and field-perpendicular wavenumbers of the fluctuations, and $b_{\\lambda}$ the fluctuating field at the scale $\\lambda\\sim 1/k_{\\perp}$. We find that when the critical balance condition, $k_{\\|}B_0\\sim k_{\\perp} b_{\\lambda}$, is satisfied, the turbulence is strong, and the energy spectrum is $E(k_{\\perp})\\propto k^{-3/2}_{\\perp}$. As the $k_{\\|}$ width of the spectrum increases, the turbulence rapidly becomes weaker, and in the limit $k_{\\|}B_0\\gg k_{\\perp} b_{\\lambda}$, the spectrum approaches $E(k_{\\perp})\\propto k_{\\perp}^{-2}$. The observed sensitivity of the spectrum to the balance of linear and nonlinear interactions may explain the conflicting numerical and observational findings where this balance condition is not well controlled.
NASA Astrophysics Data System (ADS)
Branover, Herman; Mond, Michael; Unger, Yeshajahu
The present collection of papers on MHD-related uses of liquid metal flows and their applications discusses topics in laminar MHD flows, MHD power generation, metallurgical MHD applications, and two-phase MHD flows. Attention is given to MHD flows with closed streamlines, nonlinear waves in liquid metals under a transverse magnetic field, liquid-metal MHD conversion of nuclear energy to electricity, the testing of optimized MHD conversion ('OMACON') systems, and aspects of a liquid-metal induction generator. Also discussed are MHD effects in liquid-metal breeder reactors, a plasma-driven MHD powerplant, modeling the recirculating flows in channel-induction surfaces, the hydrodynamics of aluminum reduction cells, free-surface determination in a levitation-melting process, the parametric interactions of waves in bubbly liquid metals, and the occurrence of cavitation in water jets.
Modeling open boundaries in dissipative MHD simulation
NASA Astrophysics Data System (ADS)
Meier, E. T.; Glasser, A. H.; Lukin, V. S.; Shumlak, U.
2012-04-01
The truncation of large physical domains to concentrate computational resources is necessary or desirable in simulating many natural and man-made plasma phenomena. Three open boundary condition (BC) methods for such domain truncation of dissipative magnetohydrodynamics (MHD) problems are described and compared here. A novel technique, lacuna-based open boundary conditions (LOBC), is presented for applying open BC to dissipative MHD and other hyperbolic and mixed hyperbolic-parabolic systems of partial differential equations. LOBC, based on manipulating Calderon-type near-boundary sources, essentially damp hyperbolic effects in an exterior region attached to the simulation domain and apply BC appropriate for the remaining parabolic effects (if present) at the exterior region boundary. Another technique, approximate Riemann BC (ARBC), is adapted from finite volume and discontinuous Galerkin methods. In ARBC, the value of incoming flux is specified using a local, characteristic-based method. A third commonly-used open BC, zero-normal derivative BC (ZND BC), is presented for comparison. These open BC are tested in several gas dynamics and dissipative MHD problems. LOBC are found to give stable, low-reflection solutions even in the presence of strong parabolic behavior, while ARBC are stable only when hyperbolic behavior is dominant. Pros and cons of the techniques are discussed and put into context within the body of open BC research to date.
Electron magnetohydrodynamics: Dynamics and turbulence
NASA Astrophysics Data System (ADS)
Lyutikov, Maxim
2013-11-01
We consider dynamics and turbulent interaction of whistler modes within the framework of inertialess electron magnetohydrodynamics (EMHD). We argue that there is no energy principle in EMHD: any stationary closed configuration is neutrally stable. On the other hand, the relaxation principle, the long term evolution of a weakly dissipative system towards Taylor-Beltrami state, remains valid in EMHD. We consider the turbulent cascade of whistler modes. We show that (i) harmonic whistlers are exact nonlinear solutions; (ii) collinear whistlers do not interact (including counterpropagating); (iii) waves with the same value of the wave vector k1=k2 do not interact; (iv) whistler modes have a dispersion that allows a three-wave decay, including into a zero frequency mode; (v) the three-wave interaction effectively couples modes with highly different wave numbers and propagation angles. In addition, linear interaction of a whistler with a single zero mode can lead to spatially divergent structures via parametric instability. All these properties are drastically different from MHD, so that the qualitative properties of the Alfvén turbulence can not be transferred to the EMHD turbulence. We derive the Hamiltonian formulation of EMHD, and using Bogoliubov transformation reduce it to the canonical form; we calculate the matrix elements for the three-wave interaction of whistlers. We solve numerically the kinetic equation and show that, generally, the EMHD cascade develops within a broad range of angles, while transiently it may show anisotropic, nearly two-dimensional structures. Development of a cascade depends on the forcing (nonuniversal) and often fails to reach a steady state. Analytical estimates predict the spectrum of magnetic fluctuations for the quasi-isotropic cascade ?k-2. The cascade remains weak (not critically balanced). The cascade is UV local, while the infrared locality is weakly (logarithmically) violated.
Martin, L. N.; Dmitruk, P. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina) and IFIBA, CONICET, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Gomez, D. O. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina) and IFIBA, CONICET, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio, Ciudad Universitaria, 1428 Buenos Aires (Argentina)
2010-11-15
In this work we numerically test a model of Hall magnetohydrodynamics in the presence of a strong mean magnetic field: the reduced Hall magnetohydrodynamic model (RHMHD) derived by [Gomez et al., Phys. Plasmas 15, 102303 (2008)] with the addition of weak compressible effects. The main advantage of this model lies in the reduction of computational cost. Nevertheless, up until now the degree of agreement with the original Hall MHD system and the range of validity in a regime of turbulence were not established. In this work direct numerical simulations of three-dimensional Hall MHD turbulence in the presence of a strong mean magnetic field are compared with simulations of the weak compressible RHMHD model. The results show that the degree of agreement is very high (when the different assumptions of RHMHD, such as spectral anisotropy, are satisfied). Nevertheless, when the initial conditions are isotropic but the mean magnetic field is maintained strong, the results differ at the beginning but asymptotically reach a good agreement at relatively short times. We also found evidence that the compressibility still plays a role in the dynamics of these systems, and the weak compressible RHMHD model is able to capture these effects. In conclusion the weak compressible RHMHD model is a valid approximation of the Hall MHD turbulence in the relevant physical context.
Tensor magnetohydrodynamics: Quasi-kinetic description of rarefied plasma
Laptukhov, A. I. [Russian Academy of Sciences, Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (Russian Federation)
2009-05-15
A power-series method for solving the kinetic equation is proposed. A simple procedure for deriving equations for arbitrary moments of the distribution function is described. An analysis of wave propagation in a stationary uniform hot magnetoactive plasma shows that allowance for tensors of ranks up to n and omission of higher rank tensors in the equations of tensor magnetohydrodynamics corresponds to taking into account waves at cyclotron harmonics with numbers up to n inclusive and ignoring higher harmonics. Thus, from the standpoint of accuracy and complexity of plasma description, tensor magnetohydrodynamics occupies an intermediate position between the kinetic approach and the conventional magnetohydrodynamics with a scalar pressure.
Price, Daniel
2004-01-01
an algorithm for solving the equations of Magnetohydrodynamics (MHD) using the Smoothed Particle Hydrodynamics investigate multidimensional aspects of the algorithm, refining many of the aspects considered in papers I challenges to be overcome in the numerical solution of the MHD equations. Smoothed Particle Hydrodynamics
Eikonal Method in Magnetohydrodynamics
Steven Weinberg
1962-01-01
The eikonal method is extended to waves with several components propagating in inhomogeneous anisotropic media. Formulas are derived for the motion of wave packets, the change in amplitude along a ray path, and the corrections due to diffraction. The method is applied to pure magnetohydrodynamic disturbances, and the problem of computing ray paths in the ionosphere is discussed in some
Magneto-hydrodynamically stable axisymmetric mirrors
Ryutov, D. D.; Cohen, B. I.; Molvik, A. W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Berk, H. L. [University of Texas, Austin, Texas 78712 (United States); Simonen, T. C. [University of California, Berkeley, California 94720 (United States)
2011-09-15
Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.
Magneto-hydrodynamically stable axisymmetric mirrorsa)
NASA Astrophysics Data System (ADS)
Ryutov, D. D.; Berk, H. L.; Cohen, B. I.; Molvik, A. W.; Simonen, T. C.
2011-09-01
Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.
Status of Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Lineberry, John T.
2007-01-01
Over the past several years, efforts have been under way to design and develop an operationally flexible research facility for investigating the use of cross-field MHD accelerators as a potential thrust augmentation device for thermal propulsion systems, The baseline configuration for this high-power experimental facility utilizes a 1,5-MW, multi-gas arc-heater as a thermal driver for a 2-MW, MHD accelerator, which resides in a large-bore 2-tesla electromagnet. A preliminary design study using NaK seeded nitrogen as the working fluid led to an externally diagonalized segmented MHD channel configuration based on an expendable beat-sink design concept. The current status report includes a review of engineering/design work and performance optimization analyses and summarizes component hardware fabrication and development efforts, preliminary testing results, and recent progress toward full-up assembly and testing
NASA Technical Reports Server (NTRS)
Musielak, Z. E.; Rosner, R.
1988-01-01
Magnetohydrodynamic (MHD) wave energy fluxes for late-type stars are calculated, using previously obtained formulae for the source functions for the generation of MHD waves in a stratified, but otherwise uniform, turbulent atmosphere; the magnetic fields in the wave generation region are assumed to be homogeneous. In contradiction to previous results, it is shown that in this uniform magnetic field case there is no significant increase in the efficiency of MHD wave generation, at least within the theory's limits of applicability. The major results are that the MHD energy fluxes calculated for late-type stars are less than those obtained for compressible modes in the magnetic field-free case, and that these MHD energy fluxes do not vary enough for a given spectral type to explain the observed range of UV and X-ray fluxes from such stars. It is therefore concluded that MHD waves in stellar atmospheres with homogeneous magnetic fields in the wave generation region cannot explain the observed stellar coronal emissions; if such MHD waves are responsible for a significant component of stellar coronal heating, then nonuniform fields within the generation region must be appealed to.
The modified Magnetohydrodynamic equations
Evangelos Chaliasos
2005-10-06
After finding the really self-consistent electromagnetic equations for a plasma, we proceed in a similar fashion to find how the MHD equations have to be modified accordingly. Substantially this is done by replacing the "Lorentz" force equation by the correct (in our case) force equation. Formally we have to use the vector potential instead of the magnetic field intensity.The appearance of the formulae presented is the one of classical vector analysis. We thus find a set of eight (8) equations in eight (8) unknowns, as previously known concerning the tradditional MHD equations.
Magneto-hydrodynamically stable axisymmetric mirrors
NASA Astrophysics Data System (ADS)
Ryutov, Dmitri
2010-11-01
The achievement of high beta (60%) plasma with near classical confinement in a linear axisymmetric magnetic configuration has sparked interest in the Gas Dynamic Trap concept. The significance of these results is that they can be projected directly to a neutron source for materials testing. The possibility of axisymmetric mirrors (AM) being magneto-hydrodynamically (MHD) stable is also of interest from a general physics standpoint (as it seemingly contradicts to well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a brief summary of classical results (in particular of the Rosenbluth-Longmire theory and of the energy principle as applied to AM) several approaches towards achieving MHD stabilization of the AM will be considered: 1) Employing the favorable field-line curvature in the end tanks; 2) Using the line-tying effect; 3) Setting the plasma in a slow or fast differential rotation; 4) Imposing a divertor configuration on the solenoidal magnetic field; 5) Controlling the plasma dynamics by the ponderomotive force; 6) Other techniques. Several of these approaches go beyond pure MHD and require accounting for finite Larmor radius effects and trapped particle modes. Some illuminative theoretical approaches for understanding axisymmetric mirror stability will be described. Wherever possible comparison of theoretical and experimental results on AM will be provided. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors will be discussed and the constraints on the plasma parameters will be formulated. Prepared by LLNL under Contract DE-AC52-07NA27344.
A Global Magnetohydrodynamic Model of Jovian Magnetosphere
NASA Technical Reports Server (NTRS)
Walker, Raymond J.; Sharber, James (Technical Monitor)
2001-01-01
The goal of this project was to develop a new global magnetohydrodynamic model of the interaction of the Jovian magnetosphere with the solar wind. Observations from 28 orbits of Jupiter by Galileo along with those from previous spacecraft at Jupiter, Pioneer 10 and 11, Voyager I and 2 and Ulysses, have revealed that the Jovian magnetosphere is a vast, complicated system. The Jovian aurora also has been monitored for several years. Like auroral observations at Earth, these measurements provide us with a global picture of magnetospheric dynamics. Despite this wide range of observations, we have limited quantitative understanding of the Jovian magnetosphere and how it interacts with the solar wind. For the past several years we have been working toward a quantitative understanding of the Jovian magnetosphere and its interaction with the solar wind by employing global magnetohydrodynamic simulations to model the magnetosphere. Our model has been an explicit MHD code (previously used to model the Earth's magnetosphere) to study Jupiter's magnetosphere. We continue to obtain important insights with this code, but it suffers from some severe limitations. In particular with this code we are limited to considering the region outside of 15RJ, with cell sizes of about 1.5R(sub J). The problem arises because of the presence of widely separated time scales throughout the magnetosphere. The numerical stability criterion for explicit MHD codes is the CFL limit and is given by C(sub max)(Delta)t/(Delta)x less than 1 where C(sub max) is the maximum group velocity in a given cell, (Delta)x is the grid spacing and (Delta)t is the time step. If the maximum wave velocity is C(sub w) and the flow speed is C(sub f), C(sub max) = C(sub w) + C(sub f). Near Jupiter the Alfven wave speed becomes very large (it approaches the speed of light at one Jovian radius). Operating with this time step makes the calculation essentially intractable. Therefore under this funding we have been designing a new MHD model that will be able to compute solutions in the wide parameter regime of the Jovian magnetosphere.
On the relation between viscoelastic and magnetohydrodynamic flows and their instabilities
Gordon I. Ogilvie; Michael R. E. Proctor
2002-12-19
We demonstrate a close analogy between a viscoelastic medium and an electrically conducting fluid containing a magnetic field. Specifically, the dynamics of the Oldroyd-B fluid in the limit of large Deborah number corresponds to that of a magnetohydrodynamic (MHD) fluid in the limit of large magnetic Reynolds number. As a definite example of this analogy, we compare the stability properties of differentially rotating viscoelastic and MHD flows. We show that there is an instability of the Oldroyd-B fluid that is physically distinct from both the inertial and elastic instabilities described previously in the literature, but is directly equivalent to the magnetorotational instability in MHD. It occurs even when the specific angular momentum increases outwards, provided that the angular velocity decreases outwards; it derives from the kinetic energy of the shear flow and does not depend on the curvature of the streamlines. However, we argue that the elastic instability of viscoelastic Couette flow has no direct equivalent in MHD.
STATISTICAL ANALYSIS OF CURRENT SHEETS IN THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC TURBULENCE
Zhdankin, Vladimir; Boldyrev, Stanislav [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Uzdensky, Dmitri A. [Center for Integrated Plasma Studies, Physics Department, UCB-390, University of Colorado, Boulder, CO 80309 (United States); Perez, Jean C., E-mail: zhdankin@wisc.edu, E-mail: boldyrev@wisc.edu, E-mail: uzdensky@colorado.edu, E-mail: jcperez@wisc.edu [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)
2013-07-10
We develop a framework for studying the statistical properties of current sheets in numerical simulations of magnetohydrodynamic (MHD) turbulence with a strong guide field, as modeled by reduced MHD. We describe an algorithm that identifies current sheets in a simulation snapshot and then determines their geometrical properties (including length, width, and thickness) and intensities (peak current density and total energy dissipation rate). We then apply this procedure to simulations of reduced MHD and perform a statistical analysis on the obtained population of current sheets. We evaluate the role of reconnection by separately studying the populations of current sheets which contain magnetic X-points and those which do not. We find that the statistical properties of the two populations are different in general. We compare the scaling of these properties to phenomenological predictions obtained for the inertial range of MHD turbulence. Finally, we test whether the reconnecting current sheets are consistent with the Sweet-Parker model.
C. B. Reed; R. F. Mattas; D. L. Smith; H. Chung; H. C. Tsai; W. R. Johnson; G. D. Morgan; G. W. Wille; C. Young
1996-01-01
To test the magnetohydrodynamic (MHD) pressure drop reduction performance of candidate insulator coatings for the ITER Vanadium\\/Lithium Breeding Blanket, a test section comprised of a V-4Cr-4Ti liner inside a stainless steel pipe was designed and fabricated. Theoretically, the MHD pressure drop reduction benefit resulting from an electrically insulating coating on a vanadium-lined pipe is identical to the benefit derived from
MHD Instabilities Occurring Near/AT the Transport Barrier, Including Loss of Confinement in H-Modes
L. L. Lao
1999-09-01
In configurations with transport barriers the improved edge and core confinement leads to large pressure gradient and large edge bootstrap current density which often drive magnetohydrodynamic (MHD) instabilities terminating the discharge or reducing the discharge performance. The edge and the core transport barriers deteriorate or are completely lost. In this presentation, recent experimental and theoretical developments concerning MHD instabilities occurring near/at the edge and the core transport barriers are summarized emphasizing the dominant instabilities and the comparison with theory.
A. Pouquet; E. Lee; M. E. Brachet; P. D. Mininni; D. Rosenberg
2010-01-01
We study decaying magnetohydrodynamics (MHD) turbulence stemming from the evolution of the Taylor-Green (TG) flow generalized recently to MHD, with equal viscosity and magnetic resistivity and up to equivalent grid resolutions of 2048^3 points. A pseudo-spectral code is used in which the symmetries of the velocity and magnetic fields have been implemented, allowing for sizable savings in both computer time
ELECTRON BEAM GENERATED PLASMAS IN HYPERSONIC MHD CHANNELS
Sergey O. Macheret; Mikhail N. Shneider; Richard B. Miles; Ronald J. Lipinski
The paper analyzes a novel concept of hypersonic cold-air MHD power generators and accelerators with ionization by electron beams. Ionization processes are considered in detail. Strong coupling between hypersonic boundary layers and electrode sheaths is demonstrated, and anode voltage fall in hypersonic MHD channels is shown to be very high. A potential anode sheath instability and ways to suppress it
Nonlinear closures for scale separation in supersonic magnetohydrodynamic turbulence
Grete, Philipp; Schmidt, Wolfram; Schleicher, Dominik R G; Federrath, Christoph
2015-01-01
Turbulence in compressible plasma plays a key role in many areas of astrophysics and engineering. The extreme plasma parameters in these environments, e.g. high Reynolds numbers, supersonic and super-Alfvenic flows, however, make direct numerical simulations computationally intractable even for the simplest treatment -- magnetohydrodynamics (MHD). To overcome this problem one can use subgrid-scale (SGS) closures -- models for the influence of unresolved, subgrid-scales on the resolved ones. In this work we propose and validate a set of constant coefficient closures for the resolved, compressible, ideal MHD equations. The subgrid-scale energies are modeled by Smagorinsky-like equilibrium closures. The turbulent stresses and the electromotive force (EMF) are described by expressions that are nonlinear in terms of large scale velocity and magnetic field gradients. To verify the closures we conduct a priori tests over 137 simulation snapshots from two different codes with varying ratios of thermal to magnetic pre...
Multi-Symplectic Magnetohydrodynamics: II, Addendum and Erratum
Webb, G M; Zank, G P
2015-01-01
A recent paper arXiv:1312.4890 on multi-symplectic magnetohydrodynamics (MHD) using Clebsch variables in an Eulerian action principle with constraints is further extended. We relate a class of symplecticity conservation laws to a vorticity conservation law, and provide a corrected form of the Poincar\\'e-Cartan differential form formulation of the system. We also correct some typographical errors (omissions) in arXiv:1312.4890. We show that the vorticity-symplecticity conservation law, that arises as a compatibility condition on the system, expressed in terms of the Clebsch variables is equivalent to taking the curl of the conservation form of the MHD momentum equation. We use the Cartan-Poincar\\'e form to obtain a class of differential forms that represent the system using Cartan's geometric theory of partial differential equations.
Self-heating in kinematically complex magnetohydrodynamic flows
Osmanov, Zaza; Rogava, Andria [Centre for Theoretical Astrophysics, ITP, Ilia State University, 0162-Tbilisi (Georgia); Poedts, Stefaan [Centre for Plasma Astrophysics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, Bus 2400 B-3001 (Belgium)
2012-01-15
The non-modal self-heating mechanism driven by the velocity shear in kinematically complex magnetohydrodynamic (MHD) plasma flows is considered. The study is based on the full set of MHD equations including dissipative terms. The equations are linearized and unstable modes in the flow are looked for. Two different cases are specified and studied: (a) the instability related to an exponential evolution of the wave vector and (b) the parametric instability, which takes place when the components of the wave vector evolve in time periodically. By examining the dissipative terms, it is shown that the self-heating rate provided by viscous damping is of the same order of magnitude as that due to the magnetic resistivity. It is found that the heating efficiency of the exponential instability is higher than that of the parametric instability.
A Magnetohydrodynamic Nonradiative Accretion Flow in Three Dimensions
John F. Hawley; Steven A. Balbus; James M. Stone
2001-03-30
We present a global magnetohydrodynamic (MHD) three dimensional simulation of a nonradiative accretion flow originating in a pressure supported torus. The evolution is controlled by the magnetorotational instability which produces turbulence. The flow forms a nearly Keplerian disk. The total pressure scale height in this disk is comparable to the vertical size of the initial torus. Gas pressure dominates only near the equator; magnetic pressure is more important in the surrounding atmosphere. A magnetically dominated bound outflow is driven from the disk. The accretion rate through the disk exceeds the final rate into the hole, and a hot torus forms inside 10 r_g. Hot gas, pushed up against the centrifugal barrier and confined by magnetic pressure, is ejected in a narrow, unbound, conical outflow. The dynamics are controlled by magnetic turbulence, not thermal convection, and a hydrodynamic alpha model is inadequate to describe the flow. The limitations of two dimensional MHD simulations are also discussed.
A renormalization group analysis of two-dimensional magnetohydrodynamic turbulence
NASA Technical Reports Server (NTRS)
Liang, Wenli Z.; Diamond, P. H.
1993-01-01
The renormalization group (RNG) method is used to study the physics of two-dimensional (2D) magnetohydrodynamic (MHD) turbulence. It is shown that, for a turbulent magnetofluid in two dimensions, no RNG transformation fixed point exists on account of the coexistence of energy transfer to small scales and mean-square magnetic flux transfer to large scales. The absence of a fixed point renders the RNG method incapable of describing the 2D MHD system. A similar conclusion is reached for 2D hydrodynamics, where enstrophy flows to small scales and energy to large scales. These analyses suggest that the applicability of the RNG method to turbulent systems is intrinsically limited, especially in the case of systems with dual-direction transfer.
Simulation of operation modes of a centrifugal conductive magnetohydrodynamic pump
NASA Astrophysics Data System (ADS)
Katsnelson, S. S.; Pozdnyakov, G. A.
2013-09-01
A mathematical model of a centrifugal conductive magnetohydrodynamic (MHD) pump that calculates the distributions of velocity, current density, and pressure along the channel is developed. The viscous forces in the original system of MHD equations are taken into account on the basis of the known square law of the drag for a turbulent flow in a pipe, generalized for the case of plane flows in a channel. Dependences of the drag coefficient on the main governing parameters (metal flow rate, current intensity, and intensity of magnetic induction), which provide the agreement of the calculated and experimental data on the pressure at the pump outlet for different operation modes, are obtained. It is shown that these dependences have a universal character and the proposed model can be used to design pumps of this type and to manage their operation in production industry.
Magnetohydrodynamic turbulent cascade of coronal loop magnetic fields.
Rappazzo, A F; Velli, M
2011-06-01
The Parker model for coronal heating is investigated through a high resolution simulation. An inertial range is resolved where fluctuating magnetic energy EMk[Please see symbol]) [Please see symbol] k[Please see symbol](-2.7) exceeds kinetic energy EK(k[Please see symbol])[Please see symbol]k[Please see symbol](-0.6). Increments scale as ?b? ~/= ?(-0.85) and ?u? ~/= ?(+0.2) with velocity increasing at small scales, indicating that magnetic reconnection plays a prime role in this turbulent system. We show that spectral energy transport is akin to standard magnetohydrodynamic (MHD) turbulence even for a system of reconnecting current sheets sustained by the boundary. In this new MHD turbulent cascade, kinetic energy flows are negligible while cross-field flows are enhanced, and through a series of "reflections" between the two fields, cascade more than half of the total spectral energy flow. PMID:21797433
Weijia Kuang; Jeremy Bloxham
1999-01-01
In this paper we describe a numerical model for investigating magnetohydrodynamic (MHD) convective flow of a Boussinesq fluid in a rapidly rotating spherical shell, driven by the buoyancy forces arising from incoming buoyant flux at the inner core boundary. The model is designed to investigate the generation of magnetic field in the Earth's fluid outer core. Our model differs from
Dinshaw S Balsara; Daniel S Spicer
1999-01-01
The equations of magnetohydrodynamics (MHD) have been formulated as a hyperbolic system of conservation laws. In that form it becomes possible to use higher order Godunov schemes for their solution. This results in a robust and accurate solution strategy. However, the magnetic field also satisfies a constraint that requires its divergence to be zero at all times. This is a
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, John C. (Los Alamos, NM); Swift, Gregory W. (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)
1986-01-01
A thermoacoustic magnetohydrodynamic electrical generator includes an intrinsically irreversible thermoacoustic heat engine coupled to a magnetohydrodynamic electrical generator. The heat engine includes an electrically conductive liquid metal as the working fluid and includes two heat exchange and thermoacoustic structure assemblies which drive the liquid in a push-pull arrangement to cause the liquid metal to oscillate at a resonant acoustic frequency on the order of 1,000 Hz. The engine is positioned in the field of a magnet and is oriented such that the liquid metal oscillates in a direction orthogonal to the field of the magnet, whereby an alternating electrical potential is generated in the liquid metal. Low-loss, low-inductance electrical conductors electrically connected to opposite sides of the liquid metal conduct an output signal to a transformer adapted to convert the low-voltage, high-current output signal to a more usable higher voltage, lower current signal.
Magnetic Discontinuities in Magnetohydrodynamic Turbulence and in the Solar Wind
Vladimir Zhdankin; Stanislav Boldyrev; Joanne Mason; Jean Carlos Perez
2012-04-19
Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) turbulence. We detect the discontinuities by measuring the fluctuations of the magnetic field direction, Delta theta, across fixed spatial increments Delta x in direct numerical simulations of MHD turbulence with an imposed uniform guide field B_0. A large region of the probability density function (pdf) for Delta theta is found to follow an exponential decay, proportional to exp(-Delta theta/theta_*), with characteristic angle theta_* ~ (14 deg) (b_rms/B_0)^0.65 for a broad range of guide-field strengths. We find that discontinuities observed in the solar wind can be reproduced by MHD turbulence with reasonable ratios of b_rms/B_0. We also observe an excess of small angular discontinuities when Delta x becomes small, possibly indicating an increasing statistical significance of dissipation-scale structures. The structure of the pdf in this case closely resembles the two-population pdf seen in the solar wind. We thus propose that strong discontinuities are associated with inertial-range MHD turbulence, while weak discontinuities emerge from near-dissipation-range turbulence. In addition, we find that the structure functions of the magnetic field direction exhibit anomalous scaling exponents, which indicates the existence of intermittent structures.
Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Airbreathing Hypersonic Engines
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Bityurin, Valentine A.; Lineberry, John T.
1999-01-01
Established analyses of conventional ramjet/scramjet performance characteristics indicate that a considerable decrease in efficiency can be expected at off-design flight conditions. This can be explained, in large part, by the deterioration of intake mass flow and limited inlet compression at low flight speeds and by the onset of thrust degradation effects associated with increased burner entry temperature at high flight speeds. In combination, these effects tend to impose lower and upper Mach number limits for practical flight. It has been noted, however, that Magnetohydrodynamic (MHD) energy management techniques represent a possible means for extending the flight Mach number envelope of conventional engines. By transferring enthalpy between different stages of the engine cycle, it appears that the onset of thrust degradation may be delayed to higher flight speeds. Obviously, the introduction of additional process inefficiencies is inevitable with this approach, but it is believed that these losses are more than compensated through optimization of the combustion process. The fundamental idea is to use MHD energy conversion processes to extract and bypass a portion of the intake kinetic energy around the burner. We refer to this general class of propulsion system as an MHD-bypass engine. In this paper, we quantitatively assess the performance potential and scientific feasibility of MHD-bypass airbreathing hypersonic engines using ideal gasdynamics and fundamental thermodynamic principles.
Neoclassical viscosity effects on resistive magnetohydrodynamic modes in toroidal geometry
Yang, J.G.; Oh, Y.H.; Choi, D.I. (Korea Advanced Institute of Science and Technology, Cheongyangni, P.O. Box 150, Seoul (Korea, Republic of)); Kim, J.Y.; Horton, W. (Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States))
1992-03-01
The flux-surface-averaged linearized resistive magnetohydrodynamic (MHD) boundary-layer equations including the compressibility, diamagnetic drift, and neoclassical viscosity terms are derived in toroidal geometry. These equations describe the resistive layer dynamics of resistive MHD modes over the collisionality regime between the banana plateau and the Pfirsch--Schlueter. From the resulting equations, the effects of neoclassical viscosity on the stability of the tearing and resistive ballooning modes are investigated numerically. Also, a study is given for the problem of how the neoclassical resistive MHD mode is generated as the collisionality is reduced. It is shown that the neoclassical viscosity terms give a significant destabilizing effect for the tearing and resistive ballooning modes. This destabilization comes mainly from the reduction of the stabilizing effect of the parallel ion sound compression by the ion neoclassical viscosity. In the banana-plateau collisionality limit, where the compressibility is negligible, the dispersion relations of the tearing and resistive ballooning modes reduce to the same form, with the threshold value of the driving force given by {Delta}{sub {ital c}}=0. On the other hand, with the finite neoclassical effect it is found that the neoclassical resistive MHD instability is generated in agreement with previous results. Furthermore, it is shown that this later instability can be generated in a wide range of the collisionality including near the Pfirsch--Schlueter regime as well as the banana-plateau regime, suggesting that this mode is a probable cause of anomalous transport.
THE PARABOLIC JET STRUCTURE IN M87 AS A MAGNETOHYDRODYNAMIC NOZZLE
Nakamura, Masanori; Asada, Keiichi, E-mail: nakamura@asiaa.sinica.edu.tw, E-mail: asada@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)
2013-10-01
The structure and dynamics of the M87 jet from sub-milliarcsec to arcsecond scales are continuously examined. We analyzed the Very Long Baseline Array archival data taken at 43 and 86 GHz to measure the size of very long baseline interferometry (VLBI) cores. Millimeter/sub-millimeter VLBI cores are considered as innermost jet emissions, which has been originally suggested by Blandford and Königl. Those components fairly follow an extrapolated parabolic streamline in our previous study so that the jet has a single power-law structure with nearly 5 orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 Schwarzschild radius (r{sub s}). We further inspect the jet parabolic structure as a counterpart of the magnetohydrodynamic (MHD) nozzle in order to identify the property of a bulk acceleration. We interpret that the parabolic jet consists of Poynting-flux dominated flows, powered by large-amplitude, nonlinear torsional Alfvén waves. We examine the non-relativistic MHD nozzle equation in a parabolic shape. The nature of trans-fast magnetosonic flow is similar to the one of transonic solution of Parker's hydrodynamic solar wind; the jet becomes super-escape as well as super-fast magnetosonic at around ?10{sup 3} r{sub s}, while the upstream trans-Alfvénic flow speed increases linearly as a function of the distance at ?10{sup 2}-10{sup 3} r{sub s}. We here point out that this is the first evidence to identify these features in astrophysical jets. We propose that the M87 jet is magnetically accelerated, but thermally confined by the stratified interstellar medium inside the sphere of gravitational influence of the SMBH potential, which may be a norm in active galactic nucleus jets.
DISK ACCRETION TO ROTATING MAGNETIZED STARS: MAGNETOHYDRODYNAMIC
Richardson Jr., James E.
DISK ACCRETION TO ROTATING MAGNETIZED STARS: MAGNETOHYDRODYNAMIC SIMULATIONS A Dissertation RESERVED #12;DISK ACCRETION TO ROTATING MAGNETIZED STARS: MAGNETOHYDRODYNAMIC SIMULATIONS Min Long, Ph to the complicated magnetohydrodynamic structures. The aim of this work is for understanding the accretion
Exact Controllability for the Magnetohydrodynamic Equations
Sritharan, S.S.
Exact Controllability for the Magnetohydrodynamic Equations VIOREL BARBU "Alexandru Ioan Cuza the local exact controllability of the steady state solutions of the magnetohydrodynamic equations to the global exact controllability of the null solution of the linearized magnetohydrodynamic system via
Etienne, Zachariah B.; Liu, Yuk Tung [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Shapiro, Stuart L.
2010-10-15
We have written and tested a new general relativistic magnetohydrodynamics code, capable of evolving magnetohydrodynamics (MHD) fluids in dynamical spacetimes with adaptive-mesh refinement (AMR). Our code solves the Einstein-Maxwell-MHD system of coupled equations in full 3+1 dimensions, evolving the metric via the Baumgarte-Shapiro Shibata-Nakamura formalism and the MHD and magnetic induction equations via a conservative, high-resolution shock-capturing scheme. The induction equations are recast as an evolution equation for the magnetic vector potential, which exists on a grid that is staggered with respect to the hydrodynamic and metric variables. The divergenceless constraint {nabla}{center_dot}B=0 is enforced by the curl of the vector potential. Our MHD scheme is fully compatible with AMR, so that fluids at AMR refinement boundaries maintain {nabla}{center_dot}B=0. In simulations with uniform grid spacing, our MHD scheme is numerically equivalent to a commonly used, staggered-mesh constrained-transport scheme. We present code validation test results, both in Minkowski and curved spacetimes. They include magnetized shocks, nonlinear Alfven waves, cylindrical explosions, cylindrical rotating disks, magnetized Bondi tests, and the collapse of a magnetized rotating star. Some of the more stringent tests involve black holes. We find good agreement between analytic and numerical solutions in these tests, and achieve convergence at the expected order.
Time-dependent quasi-one-dimensional flow models for linear magnetohydrodynamic generator channels
NASA Astrophysics Data System (ADS)
Massarini, A.; Borghi, C. A.
1992-09-01
A time-dependent quasi-1D approximation of a magnetohydrodynamic (MHD) compressible flow in a linear channel has been considered. For the numerical solution of the problem, three different algorithms have been utilized (MacCormack's 1969; Godunov's, 1977; and Casulli's, 1984). They are based on the finite-difference method. These models are utilized for the prediction of the behavior of electrical, thermal, and dynamic quantities during transients and during the occurrence of faults in MHD channels. A comparison of the methods when analyzing a load variation for a Faraday channel is considered.
NASA Astrophysics Data System (ADS)
Picologlou, B.; Doss, E.; Black, D.; Sikes, W. C.
1992-08-01
A two Tesla test facility was designed, built, and operated to investigate the performance of magnetohydrodynamic (MHD) seawater thrusters. The results of this investigation are used to validate MHD thruster performance computer models. The facility test loop, its components, and their design are presented in detail. Additionally, the test matrix and its rational are discussed. Finally, representative experimental results of the test program are presented, and are compared to pretest computer model predictions. Good agreement between predicted and measured data has served to validate the thruster performance computer models.
Variational integration for ideal magnetohydrodynamics with built-in advection equations
NASA Astrophysics Data System (ADS)
Zhou, Yao; Qin, Hong; Burby, J. W.; Bhattacharjee, A.
2014-10-01
Newcomb's Lagrangian for ideal magnetohydrodynamics (MHD) in Lagrangian labeling is discretized using discrete exterior calculus. Variational integrators for ideal MHD are derived thereafter. Besides being symplectic and momentum-preserving, the schemes inherit built-in advection equations from Newcomb's formulation, and therefore avoid solving them and the accompanying error and dissipation. We implement the method in 2D and show that numerical reconnection does not take place when singular current sheets are present. We then apply it to studying the dynamics of the ideal coalescence instability with multiple islands. The relaxed equilibrium state with embedded current sheets is obtained numerically.
Variational integration for ideal magnetohydrodynamics with built-in advection equations
Zhou, Yao; Burby, J. W.; Bhattacharjee, A. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Qin, Hong [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
2014-10-15
Newcomb's Lagrangian for ideal magnetohydrodynamics (MHD) in Lagrangian labeling is discretized using discrete exterior calculus. Variational integrators for ideal MHD are derived thereafter. Besides being symplectic and momentum-preserving, the schemes inherit built-in advection equations from Newcomb's formulation, and therefore avoid solving them and the accompanying error and dissipation. We implement the method in 2D and show that numerical reconnection does not take place when singular current sheets are present. We then apply it to studying the dynamics of the ideal coalescence instability with multiple islands. The relaxed equilibrium state with embedded current sheets is obtained numerically.
Nonlocality and the critical Reynolds numbers of the minimum state magnetohydrodynamic turbulence
Zhou Ye [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Oughton, Sean [Department of Mathematics, University of Waikato, Hamilton 3240 (New Zealand)
2011-07-15
Magnetohydrodynamic (MHD) systems can be strongly nonlinear (turbulent) when their kinetic and magnetic Reynolds numbers are high, as is the case in many astrophysical and space plasma flows. Unfortunately these high Reynolds numbers are typically much greater than those currently attainable in numerical simulations of MHD turbulence. A natural question to ask is how can researchers be sure that their simulations have reproduced all of the most influential physics of the flows and magnetic fields? In this paper, a metric is defined to indicate whether the necessary physics of interest has been captured. It is found that current computing resources will typically not be sufficient to achieve this minimum state metric.
Theory of energetic/alpha particle effects on magnetohydrodynamic modes in tokamaks
Chen, L.; White, R.B.; Rewoldt, G.; Colestock, P.; Rutherford, P.H.; Chen, Y.P.; Ke, F.J.; Tsai, S.T.; Bussac, M.N.
1989-01-01
The presence of energetic particles is shown to qualitatively modify the stability properties of ideal as well as resistive magnetohydrodynamic (MHD) modes in tokamaks. Specifically, we demonstrate that, consistent with highpower ICRF heating experiments in JET, high energy trapped particles can effectively stabilize the sawtooth mode, providing a possible route to stable high current tokamak operation. An alternative stabilization scheme employing barely circulating energetic particles is also proposed. Finally, we present analytical and numerical studies on the excitations of high-n MHD modes via transit resonances with circulating alpha particles. 14 refs., 3 figs.
General Relativistic MHD Simulations of Jet Formation
NASA Technical Reports Server (NTRS)
Mizuno, Y.; Nishikawa, K.-I.; Hardee, P.; Koide, S.; Fishman, G. J.
2005-01-01
We have performed 3-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of jet formation from an accretion disk with/without initial perturbation around a rotating black hole. We input a sinusoidal perturbation (m = 5 mode) in the rotation velocity of the accretion disk. The simulation results show the formation of a relativistic jet from the accretion disk. Although the initial perturbation becomes weakened by the coupling among different modes, it survives and triggers lower modes. As a result, complex non-axisymmetric density structure develops in the disk and the jet. Newtonian MHD simulations of jet formation with a non-axisymmetric mode show the growth of the m = 2 mode but GRMHD simulations cannot see the clear growth of the m = 2 mode.
Nanoflare statistics in an active region 3D MHD coronal model
NASA Astrophysics Data System (ADS)
Bingert, S.; Peter, H.
2013-02-01
Aims: We investigate the statistics for the spatial and temporal distribution of the energy input into the corona in a three-dimensional magneto-hydrodynamical (3D MHD) model. The model describes the temporal evolution of the corona above an observed active region. The model is driven by photospheric granular motions that braid the magnetic field lines. This induces currents that are dissipated, thereby leading to transient heating of the coronal plasma. We evaluate the transient heating as subsequent heating events and analyze their statistics. The results are then interpreted in the context of observed flare statistics and coronal heating mechanisms. Observed solar flares and other smaller transients cover a wide range of energies. The frequency distribution of energies follow a power law, the lower end of the distribution given by the detection limit of current instrumentation. One particular heating mechanism is based on the occurrence of so-called nanoflares, i.e. very low-energy deposition events. Methods: To conduct the numerical experiment we use a high-order finite-difference code that solves the partial differential equations for the conservation of mass, the momentum and energy balance, and the induction equation. The energy balance includes Spitzer heat conduction and optically thin radiative losses in the corona. Results: The temporal and spatial distribution of the Ohmic heating in the 3D MHD model follows a power law and can therefore be understood as a system in a self-organized critical state. The slopes of the power law are similar to the results based on observations of flares and smaller transients. We find that the coronal heating is dominated by events similar to the so-called nanoflares with energies on the order of 1017 J or 1024 erg.
V. Zheligovsky
2006-01-05
I consider the problem of weakly nonlinear stability of three-dimensional parity-invariant magnetohydrodynamic systems to perturbations, involving large scales. I assume that the MHD state, the stability of which I investigate, does not involve large spatio-temporal scales, and it is stable to perturbations involving the same small spatial scales, as the perturbed MHD state. Mean-field equations, which I derive for the perturbation using asymptotic techniques for multiscale systems, are a generalization of the standard equations of magnetohydrodynamics (the Navier-Stokes equation with the Lorentz force and the magnetic induction equation). In them, the operator of combined eddy diffusivity emerges, which is in general anisotropic and not necessarily negatively defined, and new quadratic terms, analogous to the ones describing advection. A method for efficient computation of coefficients of the eddy diffusivity tensor and eddy advection terms in the mean-field equations is proposed.
Nebogatov, V. A.; Pastukhov, V. P., E-mail: past@nfi.kiae.ru [National Research Centre Kurchatov Institute (Russian Federation)
2013-06-15
A closed set of reduced equations describing low-frequency nonlinear flute magnetohydrodynamic (MHD) convection and the resulting nondiffusive processes of particle and energy transport in a weakly collisional cylindrical plasma with an anisotropic pressure is derived. The Chew-Goldberger-Low anisotropic magnetohydrodynamics is used as the basic dynamic model, because this model is applicable to describing flute convection in a cylindrical plasma column even in the low-frequency limit. The reduced set of equations was derived using the method of adiabatic separation of fast and slow motions. It is shown that the structure of the adiabatic transformation and the corresponding velocity field are identical to those obtained earlier in the isotropic MHD model. However, the derived heat transfer equations differ drastically from the isotropic pressure model. In particular, they indicate a tendency toward maintaining different radial profiles of the longitudinal and transverse pressures.
NASA Lewis Research Center combustion MHD experiment
J. M. Smith
1982-01-01
The MHD power generation experiments were conducted in a high field strength cryomagnet which was adapted from an existing facility. In its original construction, it consisted of 12 high purity aluminum coils pool cooled in a bath of liquid neon. In this configuration, a peak field of 15 tesla was produced. For the present experiments, the center four coils were
Nonlinear magnetohydrodynamics. Progress report, July 1, 1993--June 30, 1994
Montgomery, D.C.
1994-07-30
Work has continued to focus on resistive, viscous, magnetohydrodynamic (MHD) steady states that model tokamak configurations. Recent emphasis has been on the subject of plasma rotation, and the stabilizing effects it has on the kind of MHD activity that results when current thresholds are exceeded in non-rotating configurations. The author believes that relatively superficial consequences of the effects of rotation (e.g., the {open_quotes}velocity shear layer,{close_quotes} which must result when any fluid of whatever nature is rotated in the presence of a material boundary) have been assigned causative effects that do not belong to them, in the presently-dominant perspective on the subject. Output from the author`s three-dimensional spectral-method numerical code has shown how rotation may be made to suppress helical deformations of the current channel and paired helical vortices in a supercritical magnetofluid column. A velocity {open_quotes}shear layer{close_quotes} results if and when there is wall friction. The role of ion parallel viscosity (rather than shear viscosity) in determining stability boundaries in current-carrying magnetofluids is being investigated. A lattice-Boltzmann equation method of computing three-dimensional magnetohydrodynamic toroidal effects is under consideration.
THE MHD KELVIN-HELMHOLTZ INSTABILITY III: THE ROLE OF SHEARED MAGNETIC FIELD IN PLANAR FLOWS4
Hyunju Jeong; Dongsu Ryu; T. W. Jones; Adam Frank
We have carried out simulations of the nonlinear evolution of the magnetohydrodynamic (MHD) Kelvin-Helmholtz (KH) instability for compressible fluids in 2 1 2-dimensions, extending our previous work by Frank et al. (1996) and Jones et al. (1997). In the present work we have simulated flows in the x ? y plane in which a \\
Exact solutions for MHD flow of generalized Oldroyd-B fluid due to an infinite accelerating plate
Liancun Zheng; Yaqing Liu; Xinxin Zhang
2011-01-01
This paper presents a research for the magnetohydrodynamic (MHD) flow of an incompressible generalized Oldroyd-B fluid due to an infinite accelerating plate. The motion of the fluid is produced by the infinite plate, which at time t=0+ begins to slide in its plane with a velocity At. The fractional calculus approach is introduced to establish the constitutive relationship of the
Ward B. Manchester IV; Angelos Vourlidas; Gábor Tóth; Noé Lugaz; Ilia I. Roussev; Igor V. Sokolov; Tamas I. Gombosi; Darren L. De Zeeuw; Merav Opher
2008-01-01
We numerically model the coronal mass ejection (CME) event of 2003 October 28 that erupted from AR 10486 and propagated to Earth in less than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model is formulated by first arriving at a steady state corona and solar wind employing synoptic magnetograms. We initiate two CMEs from the same active region,
J. Berchem; A. Marchaudon; M. Dunlop; C. P. Escoubet; J. M. Bosqued; H. Reme; I. Dandouras; A. Balogh; E. Lucek; C. Carr; Z. Pu
2008-01-01
This study uses two conjunctions between Cluster and Double Star TC-1 spacecraft together with global magnetohydrodynamic (MHD) simulations to investigate the large-scale configuration of magnetic reconnection at the dayside magnetopause. Both events involve southward interplanetary magnetic fields with significant B y components. The first event occurred on 8 May 2004, while both spacecraft were exploring the dawn flank of the
The PIERNIK MHD code - a multi-fluid, non-ideal extension of the relaxing-TVD scheme (II)
Micha? Hanasz; Kacper Kowalik; D. Wóltanski; R. Pawlaszek; Kacper Kornet
2010-01-01
We present a new multi-fluid, grid-based magnetohydrodynamics (MHD) code PIERNIK, which is based on the Relaxing Total Variation Diminishing (RTVD) scheme (Jin & Xin 1995). The original scheme (see Trac & Pen 2003 and Pen et al. 2003) has been extended by an addition of dynamically independent, but interacting fluids: dust and a diffusive cosmic ray (CR) gas, described within
Hyunju Jeong; Dongsu Ryu; T. W. Jones; Adam Frank
2000-01-01
We have carried out simulations of the nonlinear evolution of the magnetohydrodynamic (MHD) Kelvin-Helmholtz (KH) instability for compressible fluids in 2.5 dimensions, extending our previous work by Frank et al. and Jones et al. In the present work we have simulated flows in the x-y plane in which a ``sheared'' magnetic field of uniform strength smoothly rotates across a thin
Linda Vahala; George Vahala; Jeffrey Yepez
2003-01-01
A simplified one-dimensional (1D) magnetohydrodynamics (MHD) is solved using a lattice Boltzmann and a quantum lattice gas model. It is shown that the magnetic field decreases the strength of the velocity shock fronts, with marked spikes in the magnetic field strength that gradually broaden in time. There is very good agreement between the lattice Boltzmann modela representation of non-linear systems
A Positive Conservative Method for Magnetohydrodynamics Based on HLL and Roe Methods
P. Janhunen
2000-01-01
The exact Riemann problem solutions of the usual equations of ideal magnetohydrodynamics (MHD) can have negative pressures, if the initial data has ?ˇB??0. This creates a problem for numerical solving because in a first-order finite-volume conservative Godunov-type method one cannot avoid jumps in the normal magnetic field component even if the magnetic field was divergenceless in the three-dimensional sense. We
A High-Order WENO Finite Difference Scheme for the Equations of Ideal Magnetohydrodynamics
Guang-Shan Jiang; Cheng-Chin Wu
1999-01-01
We present a high-order accurate weighted essentially non-oscillatory (WENO) finite difference scheme for solving the equations of ideal magnetohydrodynamics (MHD). This scheme is a direct extension of a WENO scheme, which has been successfully applied to hydrodynamic problems. The WENO scheme follows the same idea of an essentially non-oscillatory (ENO) scheme with an advantage of achieving higher-order accuracy with fewer
High-beta operation and magnetohydrodynamic activity on the TFTR tokamak
K. McGuire; V. Arunasalam; C. W. Barnes; M. G. Bell; M. Bitter; R. Boivin; N. L. Bretz; R. Budny; C. E. Bush; A. Cavallo; T. K. Chu; S. A. Cohen; P. Colestock; S. L. Davis; D. L. Dimock; P. C. Efthimion; A. B. Ehrhrardt; R. J. Fonck; E. Fredrickson; H. P. Furth; G. Gammel; R. J. Goldston; G. Greene; B. Grek; L. R. Grisham; G. Hammett; R. J. Hawryluk; H. W. Hendel; K. W. Hill; E. Hinnov; D. J. Hoffman; J. Hosea; R. B. Howell; H. Hsuan; R. A. Hulse; A. C. Janos; D. Jassby; F. Jobes; D. W. Johnson; L. C. Johnson; R. Kaita; C. Kieras-Phillips; S. J. Kilpatrick; P. H. LaMarche; B. LeBlanc; D. M. Manos; D. K. Mansfield; E. Mazzucato; M. P. McCarthy; M. C. McCune; D. H. McNeill; D. M. Meade; S. S. Medley; D. R. Mikkelsen; D. Monticello; R. Motley; D. Mueller; J. A. Murphy; Y. Nagayama; D. R. Nazakian; E. B. Neischmidt; D. K. Owens; S. Pitcher; A. T. Ramsey; M. H. Redi; A. L. Roquemore; P. H. Rutherford; G. Schilling; J. Schivell; G. L. Schmidt; S. D. Scott; J. C. Sinnis; J. Stevens; B. C. Stratton; W. Stodiek; E. J. Synakowski; W. M. Tang; G. Taylor; J. R. Timberlake; H. H. Towner; M. Ulrickson; S. von Goeler; R. Wieland; M. Williams; J. R. Wilson; K.-L. Wong; M. Yamada; S. Yoshikawa; K. M. Young; M. C. Zarnstorff; S. J. Zweben
1990-01-01
Magnetohydrodynamic (MHD) activity within three zones (core, half-radius, and edge) of TFTR [PlasmaPhysicsandControlledNuclearFusionResearch1986 (IAEA, Vienna, 1987), Vol. 1, p. 51] tokamak plasmas are discussed. Near the core of the plasma column, sawteeth are often observed. Two types of sawteeth are studied in detail; one with complete, and the other with incomplete, magnetic reconnection. Their characteristics are determined by the shape
Magnetohydrodynamics from gravity
Cheng-Yong Zhang; Yi Ling; Chao Niu; Yu Tian; Xiao-Ning Wu
2012-06-28
Imposing the Petrov-like boundary condition on the hypersurface at finite cutoff, we derive the hydrodynamic equation on the hypersurface from the bulk Einstein equation with electromagnetic field in the near horizon limit. We first get the general framework for spacetime with matter field, and then derive the incompressible Navier-Stokes equations for black holes with electric charge and magnetic charge respectively. Especially, in the magnetic case, the standard magnetohydrodynamic equations will arise due to the existence of the background electromagnetic field on the hypersurface.
Magnetohydrodynamics of fractal media
Tarasov, Vasily E. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119992 (Russian Federation)
2006-05-15
The fractal distribution of charged particles is considered. An example of this distribution is the charged particles that are distributed over the fractal. The fractional integrals are used to describe fractal distribution. These integrals are considered as approximations of integrals on fractals. Typical turbulent media could be of a fractal structure and the corresponding equations should be changed to include the fractal features of the media. The magnetohydrodynamics equations for fractal media are derived from the fractional generalization of integral Maxwell equations and integral hydrodynamics (balance) equations. Possible equilibrium states for these equations are considered.
Solar wind turbulence: Observations of MHD effects
NASA Technical Reports Server (NTRS)
Bavassano, B.
1995-01-01
Since the first in-situ observations it was realized that the solar wind is permeated by large-amplitude variations on a very extended range of scales. In this paper an overview of our present state of knowledge for fluctuations in the magnetohydrodynamic (MHD) regime is given. These fluctuations are an important component of the solar wind variability and notably contribute to the overall energy and momentum flux. They generally have a turbulent character and their amplitude is large enough to suggest the presence of nonlinear effects. In recent years the use of high time-resolution data on an extended range of heliocentric distances has allowed major steps towards a satisfactory understanding of the solar wind MHD fluctuations. Their radial evolution in the expanding wind has been determined through detailed analyses of the variations in their spectral features. correlations. and anisotropics. The role of interplanetary sources has been carefully investigated. The influence of interactions with structures convected by the solar wind has been examined. Fluctuations have been studied in the light of theories developed to draw together the effects of both incompressibility and compressibility. Increasing attention has been devoted to the intermittent character of the turbulence. Finally, very recent observations by Ulysses at high heliographic latitudes have allowed the first in-situ analysis of turbulence features in polar regions of the heliosphere.
White, M.K.
1993-11-01
Corrosion data have been obtained for tub is exposed for 1500--2000 hours in a proof-of-concept magnetohydrodynamics (MHD) power generation test facility to conditions representative of superheater and intermediate temperature air heater (ITAH) components. The tubes, coated with K{sub 2}SO{sub 4}-rich deposits, were corroded more than in most pulverized coal fired superheater service, but much less than the highly aggressive liquid phase attack encountered in conventional plants with certain coals and temperatures. Results indicated that, with parabolic corrosion kinetics, type 310 and 253MA stainless steels should be usable to 1400F at hot end of ITAH. At final superheater temperatures, 2.25 and 5 Cr steels were indicated to have parabolic corrosion rates generally below a 0.5 mm/yr criterion, based on corrosion scale thickness. However, unknown amounts of scale loss from spallation made this determination uncertain. Stainless steels 304H, 316H, and 321H had parabolic rates variably above the criterion, but may be servicable under less cyclic conditions. Corrosion rates derived from scale thickness and intergranular corrosion depth measurements are reported, along with scale morphologies and compositions. Implications of results on commercial MHD utilization of the alloys are discussed, as well as the indicated need for more corrosion resistant alloys or coatings under the most severe exposure conditions.
Stabilization of global MHD instabilities by toroidal plasma rotation
Chu, M.S.; Miller, R.L. [General Atomics, San Diego, CA (United States); Bondeson, A. [Uppsala Univ. (Sweden); Luetjens, H. [Ecole Polytechnique, Palaiseau (France); DeRidder, G.; Sauter, O. [CRPP/EPFL, Lausanne (Switzerland)
1995-07-01
Theoretical study and experimental observations suggest that rotation can play a crucial role in determining plasma stability. Since conventional magnetohydrodynamic (MHD) analysis ignores rotation, more advanced computational tools are being developed to confirm the theoretical understanding and to perform comparison between theory and experiment. In a previous work, the authors reported on the formulation and computation of MHD modes in plasmas with a small (subsonic) toroidal rotation. R.otation is found to have a substantial stabilizing effect under many circumstances. In this work, they extend the formulation in Ref. 4 to include an arbitrary (large) toroidal plasma rotation. It is the purpose of this work to examine the difference between these two formulations and report on results from computations using these formulations.
Magnetohydrodynamic generator experimental studies
NASA Technical Reports Server (NTRS)
Pierson, E. S.
1972-01-01
The results for an experimental study of a one wavelength MHD induction generator operating on a liquid flow are presented. First the design philosophy and the experimental generator design are summarized, including a description of the flow loop and instrumentation. Next a Fourier series method of treating the fact that the magnetic flux density produced by the stator is not a pure traveling sinusoid is described and some results summarized. This approach appears to be of interest after revisions are made, but the initial results are not accurate. Finally, some of the experimental data is summarized for various methods of excitation.
Comparison of three artificial models of the magnetohydrodynamic effect on the electrocardiogram.
Oster, Julien; Llinares, Raul; Payne, Stephen; Tse, Zion Tsz Ho; Schmidt, Ehud Jeruham; Clifford, Gari D
2015-01-01
The electrocardiogram (ECG) is often acquired during magnetic resonance imaging (MRI), but its analysis is restricted by the presence of a strong artefact, called magnetohydrodynamic (MHD) effect. MHD effect is induced by the flow of electrically charged particles in the blood perpendicular to the static magnetic field, which creates a potential of the order of magnitude of the ECG and temporally coincident with the repolarisation period. In this study, a new MHD model is proposed by using MRI-based 4D blood flow measurements made across the aortic arch. The model is extended to several cardiac cycles to allow the simulation of a realistic ECG acquisition during MRI examination and the quality assessment of MHD suppression techniques. A comparison of two existing models, based, respectively, on an analytical solution and on a numerical method-based solution of the fluids dynamics problem, is made with the proposed model and with an estimate of the MHD voltage observed during a real MRI scan. Results indicate a moderate agreement between the proposed model and the estimated MHD model for most leads, with an average correlation factor of 0.47. However, the results demonstrate that the proposed model provides a closer approximation to the observed MHD effects and a better depiction of the complexity of the MHD effect compared with the previously published models, with an improved correlation (+5%), coefficient of determination (+22%) and fraction of energy (+1%) compared with the best previous model. The source code will be made freely available under an open source licence to facilitate collaboration and allow more rapid development of more accurate models of the MHD effect. PMID:24761753
A kinetic-MHD model for low frequency phenomena
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 {tau} 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.
Vortex laws and field line invariants in polytropic field-aligned MHD flow
NASA Astrophysics Data System (ADS)
Sonnerup, B. U. O.; Hau, L.-N.
1994-01-01
The consequences of conservation of angular momentum in, single- or double-polytropic, steady, compressible, magnetohydrodynamic (MHD) flow parallel to the magnetic field are examined, the principal result being the MHD counterparts of Crocco's theorem and Lord Kelvin's theorem, both expressed in terms of a generalized vorticity. Under special assumptions concerning geometry and/or homogeneity of the general field line invariants, these vortex laws lead to additional field line invariants which describe the conservation of generalized angular momentum in the plasma, taking into account torques produced by j x B forces and Coriolis forces.
A general Cluster data and global MHD simulation comparison
NASA Astrophysics Data System (ADS)
Daum, P.; Denton, M. H.; Wild, J. A.; Taylor, M. G. G. T.; Afránková, J. Ĺ.; Hayosh, M.
2008-11-01
Among the many challenges facing the space weather modelling community today, is the need for validation and verification methods of the numerical models available describing the complex nonlinear Sun-Earth system. Magnetohydrodynamic (MHD) models represent the latest numerical models of this environment and have the unique ability to span the enormous distances present in the magnetosphere, from several hundred kilometres to several thousand kilometres above the Earth's surface. This makes it especially difficult to develop verification and validation methods which posses the same range spans as the models. In this paper we present a first general large-scale comparison between four years (2001 2004) worth of in situ Cluster plasma observations and the corresponding simulated predictions from the coupled Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme (BATS-R-US) MHD code. The comparison between the in situ measurements and the model predictions reveals that by systematically constraining the MHD model inflow boundary conditions a good correlation between the in situ observations and the modeled data can be found. These results have an implication for modelling studies addressing also smaller scale features of the magnetosphere. The global MHD simulation can therefore be used to place localised satellite and/or ground-based observations into a global context and fill the gaps left by measurements.
Electrical characteristics of a seawater MHD thruster. Final report
Tempelmeyer, K.E.
1990-06-01
There is renewed interest in the application of the magnetohydrodynamic (MHD) propulsion concept to marine propulsion. However, there is almost no experimental information concerning the major physical processes which will occur in a seawater MHD propulsion unit, such as (1) the seawater electrolysis process at operational conditions needed for ship propulsion, (2) the effects of bubble formation on the performance of a seawater thruster and (3) the effectiveness of the MHD interaction in seawater. Small scale tests of an MHD type channel but without an applied magnetic field have been carried out to provide information about the first two of these areas (1) seawater electrolysis and (2) the effect of the H2 bubbles generated during the electrolysis of seawater. Current/voltage characteristics were obtained with different electrode materials for current densities up to 0.3 amp/sq cm. The effect of bubble formation on the channel current has been assessed over a range of operating conditions. Long-duration tests to 100 hrs have been made to provide information on electrode durability and long-term operational problems.
MHD stability and fluctuations
A. C. Sicardi Schifino; C. Ferro Fontán
1989-01-01
The effect of fluctuations on the stability of magnetohydrodynamic plasma equilibria is studied by the direct Lyapunov method, using the Fokker-Planck equation to model stationary random fluctuations. A fluctuation-dissipation theorem is derived and it is demonstrated that a deterministic stable system is not destabilized by the fluctuations. Member of ``Carrera del Investigador Científico del Consejo Nacional de Investigaciones Científicas y
Implicit Predictor-Corrector finite difference scheme for the ideal MHD simulations
NASA Astrophysics Data System (ADS)
Tsai, T.; Yu, H.; Lai, S.
2012-12-01
A innovative simulation code for ideal magnetohydrodynamics (MHD) is developed. We present a multiple-dimensional MHD code based on high-order implicit predictor-corrector finite difference scheme (high-order IPCFD scheme). High-order IPCFD scheme adopts high-order predictor-corrector scheme for the time integration and high-order central difference method as the spatial derivative solver. We use Elimination-of-the-Runoff-Errors (ERE) technology to avoid the numerical oscillations and numerical instability in the simulation results. In one-dimensional MHD problem, our simulation results show good agreement with the Brio & Wu MHD shock tube problem. The divergent B constraint remains fully satisfied, that is the divergent B equals to zero throughout the simulation. When solving the two-dimensional (2D) linear wave in MHD plasma, we clearly obtain the group-velocity Friedrichs diagrams of the MHD waves. Here we demonstrate 2D simulation results of rotor problem, Orszag-Tang vortex system, vortex type K-H instability, and kink type K-H instability by using our IPCFD MHD code and discuss the advantage of our simulation code.
Liquid-metal magnetohydrodynamic system evaluation. [coal-fired designs
NASA Technical Reports Server (NTRS)
Holman, R. R.; Lippert, T. E.
1976-01-01
The present study emphasizes a direct coal-fired design using a bubbly two-component flow of sodium and argon in the MHD generator and a Rankine steam-bottoming plant. Two basic cycles were studied, corresponding to argon temperatures of 922 and 1089 K at the duct inlet. The MHD duct system consisted of multiple ducts arranged in clusters and separated by iron magnet pole pieces. The ducts, each with an output of about 100 MW, were parallel to the flow, but were connected in series electrically to provide a higher MHD voltage. With channel efficiencies of 80%, a pump efficiency of 90%, and a 45% efficient steam-bottoming plant, the overall efficiency of the 1089 K liquid-metal MHD power plant was 43%.
The Classification of Magnetohydrodynamic Regimes of Thermonuclear Combustion
NASA Astrophysics Data System (ADS)
Remming, Ian S.; Khokhlov, Alexei M.
2014-10-01
Physical properties of magnetohydrodynamic (MHD) reaction fronts are studied as functions of the thermodynamic conditions, and the strength and orientation of the magnetic field in the unburned matter through which the fronts propagate. We determine the conditions for the existence of the various types of MHD reaction fronts and the character of the changes in physical quantities across these reaction fronts. The analysis is carried out in general for a perfect gas equation of state and a constant energy release, and then extended to thermonuclear reaction fronts in degenerate carbon-oxygen mixtures and degenerate helium in conditions typical of Type Ia supernova explosions. We find that as unburned matter enters perpendicular to a reaction front, the release of energy through burning generates shear velocity in the reacting gas that, depending on the type of reaction front, strengthens or weakens the magnetic field. In addition, we find that the steady-state propagation of a reaction front is impossible for certain ranges of magnetic field direction. Our results provide insight into the phenomena of MHD thermonuclear combustion that is relevant to the interpretation of future simulations of SN Ia explosions that have magnetic fields systematically incorporated.
Some topics in the magnetohydrodynamics of accreting magnetic compact objects
NASA Technical Reports Server (NTRS)
Aly, J. J.
1986-01-01
Magnetic compact objects (neutron stars or white dwarfs) are currently thought to be present in many accreting systems that are releasing large amounts of energy. The magnetic field of the compact star may interact strongly with the accretion flow and play an essential role in the physics of these systems. Some magnetohydrodynamic (MHD) problems that are likely to be relevant in building up self-consistent models of the interaction between the accreting plasma and the star's magnetosphere are addressed in this series of lectures. The basic principles of MHD are first introduced and some important MHD mechanisms (Rayleigh-Taylor and Kelvin-Helmholtz instabilities; reconnection) are discussed, with particular reference to their role in allowing the infalling matter to penetrate the magnetosphere and mix with the field. The structure of a force-free magnetosphere and the possibility of quasistatic momentum and energy transfer between regions linked by field-aligned currents are then studied in some detail. Finally, the structure of axisymmetric accretion flows onto magnetic compact objects is considered.
RADIATION MAGNETOHYDRODYNAMIC SIMULATIONS OF PROTOSTELLAR COLLAPSE: PROTOSTELLAR CORE FORMATION
Tomida, Kengo [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)] [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Tomisaka, Kohji [Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), Osawa, Mitaka, Tokyo 181-8588 (Japan)] [Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), Osawa, Mitaka, Tokyo 181-8588 (Japan); Matsumoto, Tomoaki [Faculty of Humanity and Environment, Hosei University, Fujimi, Chiyoda-ku, Tokyo 102-8160 (Japan)] [Faculty of Humanity and Environment, Hosei University, Fujimi, Chiyoda-ku, Tokyo 102-8160 (Japan); Hori, Yasunori; Saigo, Kazuya [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)] [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Okuzumi, Satoshi [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan)] [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan); Machida, Masahiro N., E-mail: tomida@astro.princeton.edu, E-mail: tomisaka@th.nao.ac.jp, E-mail: yasunori.hori@nao.ac.jp, E-mail: saigo.kazuya@nao.ac.jp, E-mail: matsu@hosei.ac.jp, E-mail: okuzumi@nagoya-u.jp, E-mail: machida.masahiro.018@m.kyushu-u.ac.jp [Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)
2013-01-20
We report the first three-dimensional radiation magnetohydrodynamic (RMHD) simulations of protostellar collapse with and without Ohmic dissipation. We take into account many physical processes required to study star formation processes, including a realistic equation of state. We follow the evolution from molecular cloud cores until protostellar cores are formed with sufficiently high resolutions without introducing a sink particle. The physical processes involved in the simulations and adopted numerical methods are described in detail. We can calculate only about one year after the formation of the protostellar cores with our direct three-dimensional RMHD simulations because of the extremely short timescale in the deep interior of the formed protostellar cores, but successfully describe the early phase of star formation processes. The thermal evolution and the structure of the first and second (protostellar) cores are consistent with previous one-dimensional simulations using full radiation transfer, but differ considerably from preceding multi-dimensional studies with the barotropic approximation. The protostellar cores evolve virtually spherically symmetric in the ideal MHD models because of efficient angular momentum transport by magnetic fields, but Ohmic dissipation enables the formation of the circumstellar disks in the vicinity of the protostellar cores as in previous MHD studies with the barotropic approximation. The formed disks are still small (less than 0.35 AU) because we simulate only the earliest evolution. We also confirm that two different types of outflows are naturally launched by magnetic fields from the first cores and protostellar cores in the resistive MHD models.
CONSTRAINED-TRANSPORT MAGNETOHYDRODYNAMICS WITH ADAPTIVE MESH REFINEMENT IN CHARM
Miniati, Francesco [Physics Department, Wolfgang-Pauli-Strasse 27, ETH-Zuerich, CH-8093 Zuerich (Switzerland); Martin, Daniel F., E-mail: fm@phys.ethz.ch, E-mail: DFMartin@lbl.gov [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)
2011-07-01
We present the implementation of a three-dimensional, second-order accurate Godunov-type algorithm for magnetohydrodynamics (MHD) in the adaptive-mesh-refinement (AMR) cosmological code CHARM. The algorithm is based on the full 12-solve spatially unsplit corner-transport-upwind (CTU) scheme. The fluid quantities are cell-centered and are updated using the piecewise-parabolic method (PPM), while the magnetic field variables are face-centered and are evolved through application of the Stokes theorem on cell edges via a constrained-transport (CT) method. The so-called multidimensional MHD source terms required in the predictor step for high-order accuracy are applied in a simplified form which reduces their complexity in three dimensions without loss of accuracy or robustness. The algorithm is implemented on an AMR framework which requires specific synchronization steps across refinement levels. These include face-centered restriction and prolongation operations and a reflux-curl operation, which maintains a solenoidal magnetic field across refinement boundaries. The code is tested against a large suite of test problems, including convergence tests in smooth flows, shock-tube tests, classical two- and three-dimensional MHD tests, a three-dimensional shock-cloud interaction problem, and the formation of a cluster of galaxies in a fully cosmological context. The magnetic field divergence is shown to remain negligible throughout.
SHEAR-DRIVEN INSTABILITIES IN HALL-MAGNETOHYDRODYNAMIC PLASMAS
Bejarano, Cecilia; Gomez, Daniel O. [Instituto de Astronomia y Fisica del Espacio (Consejo Nacional de Investigaciones Cientificas y Tecnicas, Universidad de Buenos Aires), Ciudad Universitaria, 1428 C.A.B.A., Buenos Aires (Argentina); Brandenburg, Axel, E-mail: cbejarano@iafe.uba.ar, E-mail: gomez@iafe.uba.ar, E-mail: brandenb@nordita.org [NORDITA, AlbaNova University Center, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)
2011-08-20
The large-scale dynamics of plasmas is well described within the framework of magnetohydrodynamics (MHD). However, whenever the ion density of the plasma becomes sufficiently low, the Hall effect is likely to become important. The role of the Hall effect has been studied in several astrophysical plasma processes, such as magnetic reconnection, magnetic dynamo, MHD turbulence, or MHD instabilities. In particular, the development of small-scale instabilities is essential to understand the transport properties in a number of astrophysical plasmas. The magneto-rotational instability (MRI), which takes place in differentially rotating accretion disks embedded in relatively weak magnetic fields, is just one example. The influence of the large-scale velocity flows on small-scale instabilities is often approximated by a linear shear flow. In this paper, we quantitatively study the role of the Hall effect on plasmas embedded in large-scale shear flows. More precisely, we show that an instability develops when the Hall effect is present, which we therefore term as the Hall magneto-shear instability. As a particular case, we recover the so-called MRI and quantitatively assess the role of the Hall effect on its development and evolution.
T. Tanaka
1994-01-01
A three-dimensional (3D) high-resolution magnetohydrodynamic (MHD) simulation scheme on an unstructured grid system is developed for inhomogeneous systems, including strong background potential fields. The scheme is based on the finite volume method (FVM) with an upwinding numerical flux by the linearized Riemann solver. Upwindings on an unstructured grid system are realized from the fact that the MHD equations are symmetric
Small-scale dynamo action in multi-scale magnetohydrodynamic and micro-turbulence
NASA Astrophysics Data System (ADS)
Li, Jiquan; Kishimoto, Y.
2012-03-01
Nonlinear interplay between resistive magnetohydrodynamic (MHD) magnetic island and drift wave micro-turbulence is investigated using direct Landau-fluid simulations. A twisting oscillation of magnetic island associated with the driving force of micro-turbulence is observed, which is referred to as magnetic island seesaw. In the initiating phase of the seesaw oscillation, small-scale current and magnetic field fluctuations increase dramatically while the magnetic induction grows exponentially at small-scales corresponding to the spatial scale of micro-turbulence, showing a small-scale dynamo action. A minimal model consisting of reduced MHD turbulence and a micro-instability is proposed to elucidate the underlying mechanism. It is identified that the island seesaw is driven by a net oscillatory electromagnetic torque, which results from small-scale dynamo-generated current and magnetic field. The dynamo mechanism may offer an important energy exchange channel between MHD and micro-turbulence in magnetic fusion plasmas.
Self-gravitational Magnetohydrodynamics with Adaptive Mesh Refinement for Protostellar Collapse
Tomoaki Matsumoto
2007-10-07
A new numerical code, called SFUMATO, for solving self-gravitational magnetohydrodynamics (MHD) problems using adaptive mesh refinement (AMR) is presented. A block-structured grid is adopted as the grid of the AMR hierarchy. The total variation diminishing (TVD) cell-centered scheme is adopted as the MHD solver, with hyperbolic cleaning of divergence error of the magnetic field also implemented. The self-gravity is solved by a multigrid method composed of (1) full multigrid (FMG)-cycle on the AMR hierarchical grids, (2) V-cycle on these grids, and (3) FMG-cycle on the base grid. The multigrid method exhibits spatial second-order accuracy, fast convergence, and scalability. The numerical fluxes are conserved by using a refluxing procedure in both the MHD solver and the multigrid method. The several tests are performed indicating that the solutions are consistent with previously published results.
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, J.C.; Swift, G.W.; Migliori, A.
1986-07-08
A thermoacoustic magnetohydrodynamic electrical generator is described comprising a magnet having a magnetic field, an elongate hollow housing containing an electrically conductive liquid and a thermoacoustic structure positioned in the liquid, heat exchange means thermally connected to the thermoacoustic structure for inducing the liquid to oscillate at an acoustic resonant frequency within the housing. The housing is positioned in the magnetic field and oriented such that the direction of the magnetic field and the direction of oscillatory motion of the liquid are substantially orthogonal to one another, first and second electrical conductor means connected to the liquid on opposite sides of the housing along an axis which is substantially orthogonal to both the direction of the magnetic field and the direction of oscillatory motion of the liquid, an alternating current output signal is generated in the conductor means at a frequency corresponding to the frequency of the oscillatory motion of the liquid.
Spectrum of magnetohydrodynamic turbulence
Stanislav Boldyrev
2006-02-24
We propose a phenomenological theory of strong incompressible magnetohydrodynamic turbulence in the presence of a strong large-scale external magnetic field. We argue that in the inertial range of scales, magnetic-field and velocity-field fluctuations tend to align the directions of their polarizations. However, the perfect alignment cannot be reached, it is precluded by the presence of a constant energy flux over scales. As a consequence, the directions of fluid and magnetic-field fluctuations at each scale $\\lambda$ become effectively aligned within the angle $\\phi_{\\lambda}\\propto \\lambda^{1/4}$, which leads to scale-dependent depletion of nonlinear interaction and to the field-perpendicular energy spectrum $E(k_{\\perp})\\propto k_{\\perp}^{-3/2}$. Our results may be universal, i.e., independent of the external magnetic field, since small-scale fluctuations locally experience a strong field produced by large-scale eddies.
Magnetohydrodynamic Origin of Jets from Accretion Disks
NASA Technical Reports Server (NTRS)
Lovelace, R. V. E.; Romanova, M. M.
1998-01-01
A review is made of magnetohydrodynamic (MHD) theory and simulation of outflows from disks for different distributions of magnetic field threading the disk. In one limit of a relatively weak, initially diverging magnetic field, both thermal and magnetic pressure gradients act to drive matter to an outflow, while a toroidal magnetic field develops which strongly collimates the outflow. The collimation greatly reduces the field divergence and the mass outflow rate decreases after an initial peak. In a second limit of a strong magnetic field, the initial field configuration was taken with the field strength on the disk decreasing outwards to small values so that collimation was reduced. As a result, a family of stationary solutions was discovered where matter is driven mainly by the strong magnetic pressure gradient force. The collimation in this case depends on the pressure of an external medium. These flows are qualitatively similar to the analytic solutions for magnetically driven outflows. The problem of the opening of a closed field line configuration linking a magnetized star and an accretion disk is also discussed.
A Fast MHD Code for Gravitationally Stratified Media using Graphical Processing Units: SMAUG
NASA Astrophysics Data System (ADS)
Griffiths, M. K.; Fedun, V.; Erdélyi, R.
2015-03-01
Parallelization techniques have been exploited most successfully by the gaming/graphics industry with the adoption of graphical processing units (GPUs), possessing hundreds of processor cores. The opportunity has been recognized by the computational sciences and engineering communities, who have recently harnessed successfully the numerical performance of GPUs. For example, parallel magnetohydrodynamic (MHD) algorithms are important for numerical modelling of highly inhomogeneous solar, astrophysical and geophysical plasmas. Here, we describe the implementation of SMAUG, the Sheffield Magnetohydrodynamics Algorithm Using GPUs. SMAUG is a 1-3D MHD code capable of modelling magnetized and gravitationally stratified plasma. The objective of this paper is to present the numerical methods and techniques used for porting the code to this novel and highly parallel compute architecture. The methods employed are justified by the performance benchmarks and validation results demonstrating that the code successfully simulates the physics for a range of test scenarios including a full 3D realistic model of wave propagation in the solar atmosphere.
A Fast MHD Code for Gravitationally Stratified Media using Graphical Processing Units: SMAUG
NASA Astrophysics Data System (ADS)
Griffiths, M. K.; Fedun, V.; Erdélyi, R.
2015-05-01
Parallelization techniques have been exploited most successfully by the gaming/graphics industry with the adoption of graphical processing units (GPUs), possessing hundreds of processor cores. The opportunity has been recognized by the computational sciences and engineering communities, who have recently harnessed successfully the numerical performance of GPUs. For example, parallel magnetohydrodynamic (MHD) algorithms are important for numerical modelling of highly inhomogeneous solar, astrophysical and geophysical plasmas. Here, we describe the implementation of SMAUG, the Sheffield Magnetohydrodynamics Algorithm Using GPUs. SMAUG is a 1-3D MHD code capable of modelling magnetized and gravitationally stratified plasma. The objective of this paper is to present the numerical methods and techniques used for porting the code to this novel and highly parallel compute architecture. The methods employed are justified by the performance benchmarks and validation results demonstrating that the code successfully simulates the physics for a range of test scenarios including a full 3D realistic model of wave propagation in the solar atmosphere.
Some Exact Solutions of Magnetohydrodynamics
Mahinder S. Uberoi
1963-01-01
Four examples of the exact solutions of two-dimensional magnetohydrodynamics of incompressible inviscid fluid are given. Two are valid for infinite conductivity and the other two for finite conductivity.
Some Exact Solutions of Magnetohydrodynamics
Mahinder S. Uberoi
1963-01-01
Four examples of the exact solutions of two-dimensional ; magnetohydrodynamics of incompressible inviscid fluid are given. Two are valid ; for infinite conductivity and the other two for finite conductivity. (auth);
Price, Daniel
2010-01-01
for SPMHD. Key words: magnetic fields MHD shock waves methods: numerical stars: formation. 1 Particle Magnetohydrodynamics IV. Using the vector potential Daniel J. Price Centre for Stellar investigate the use of the vector potential as a means of maintaining the diver- gence constraint
On computations for thermal radiation in MHD channel flow with heat and mass transfer.
Hayat, T; Awais, M; Alsaedi, A; Safdar, Ambreen
2014-01-01
This study examines the simultaneous effects of heat and mass transfer on the three-dimensional boundary layer flow of viscous fluid between two infinite parallel plates. Magnetohydrodynamic (MHD) and thermal radiation effects are present. The governing problems are first modeled and then solved by homotopy analysis method (HAM). Influence of several embedded parameters on the velocity, concentration and temperature fields are described. PMID:24497968
Three-dimensional MHD simulation of a flux rope driven CME
Ward B. Manchester; Tamas I. Gombosi; Ilia Roussev; Darren L. De Zeeuw; I. V. Sokolov; Kenneth G. Powell; Gábor Tóth; Merav Opher
2004-01-01
We present a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD) model, describing the time-dependent expulsion of plasma and magnetic flux from the solar corona that resembles a coronal mass ejection (CME). We begin by developing a global steady-state model of the corona and solar wind that gives a reasonable description of the solar wind conditions near solar minimum. The model magnetic
Hall effects on MHD flow in a rotating system with heat transfer characteristics
S. K. Ghosh; O. Anwar Bég; M. Narahari
2009-01-01
Closed-form solutions are derived for the steady magnetohydrodynamic (MHD) viscous flow in a parallel plate channel system\\u000a with perfectly conducting walls in a rotating frame of reference, in the presence of Hall currents, heat transfer and a transverse\\u000a uniform magnetic field. A mathematical analysis is described to evaluate the velocity, induced magnetic field and mass flow\\u000a rate distributions, for a
NASA Astrophysics Data System (ADS)
Galperti, C.; Marchetto, C.; Alessi, E.; Minelli, D.; Mosconi, M.; Belli, F.; Boncagni, L.; Botrugno, A.; Buratti, P.; Calabro', G.; Esposito, B.; Garavaglia, S.; Granucci, G.; Grosso, A.; Mellera, V.; Moro, A.; Piergotti, V.; Pucella, G.; Ramogida, G.; Bin, W.; Sozzi, C.
2014-11-01
The biorthogonal decomposition analysis of signals from an array of Mirnov coils is able to provide the spatial structure and the temporal evolution of magnetohydrodynamic (MHD) instabilities in a tokamak. Such analysis can be adapted to a data acquisition and elaboration system suitable for fast real time applications such as instability detection and disruption precursory markers computation. This paper deals with the description of this technique as applied to the Frascati Tokamak Upgrade (FTU).
On Computations for Thermal Radiation in MHD Channel Flow with Heat and Mass Transfer
Hayat, T.; Awais, M.; Alsaedi, A.; Safdar, Ambreen
2014-01-01
This study examines the simultaneous effects of heat and mass transfer on the three-dimensional boundary layer flow of viscous fluid between two infinite parallel plates. Magnetohydrodynamic (MHD) and thermal radiation effects are present. The governing problems are first modeled and then solved by homotopy analysis method (HAM). Influence of several embedded parameters on the velocity, concentration and temperature fields are described. PMID:24497968
Real-time diagnostics at ASDEX UpgradeIntegration with MHD feedback control
W. Treutterer; K. Behler; L. Giannone; N. Hicks; A. Manini; M. Maraschek; G. Raupp; M. Reich; A. C. C. Sips; J. Stober; W. Suttrop
2008-01-01
At the ASDEX Upgrade tokamak experiment, a new feedback control loop is under construction with the aim of stabilizing magneto-hydrodynamic (MHD) instabilities, such as neoclassical tearing modes and sawteeth. It uses the mirrors of the electron cyclotron heating (ECH) launchers, which can be steered in real-time to guide each beam to the position needed to stabilize and suppress the mode.The
Field topologies in ideal and near-ideal magnetohydrodynamics and vortex dynamics
NASA Astrophysics Data System (ADS)
Low, B. C.
2015-01-01
Magnetic field topology frozen in ideal magnetohydrodynamics (MHD) and its breakage in near-ideal MHD are reviewed in two parts, clarifying and expanding basic concepts. The first part gives a physically complete description of the frozen field topology derived from magnetic flux conservation as the fundamental property, treating four conceptually related topics: Eulerian and Lagrangian descriptions of three dimensional (3D) MHD, Chandrasekhar-Kendall and Euler-potential field representations, magnetic helicity, and inviscid vortex dynamics as a fluid system in physical contrast to ideal MHD. A corollary of these developments clarifies the challenge of achieving a high degree of the frozen-in condition in numerical MHD. The second part treats field-topology breakage centered around the Parker Magnetostatic Theorem on a general incompatibility of a continuous magnetic field with the dual demand of force-free equilibrium and an arbitrarily prescribed, 3D field topology. Preserving field topology as a global constraint readily results in formation of tangential magnetic discontinuities, or, equivalently, electric current-sheets of zero thickness. A similar incompatibility is present in the steady force-thermal balance of a heated radiating fluid subject to an anisotropic thermal flux conducted strictly along its frozen-in magnetic field in the low- ? limit. In a weakly resistive fluid the thinning of current sheets by these general incompatibilities inevitably results in sheet dissipation, resistive heating and topological changes in the field notwithstanding the small resistivity. Strong Faraday induction drives but also macroscopically limits this mode of energy dissipation, trapping or storing free energy in self-organized ideal-MHD structures. This property of MHD turbulence captured by the Taylor hypothesis is reviewed in relation to the Sun's corona, calling for a basic quantitative description of the breakdown of flux conservation in the low-resistivity limit. A cylindrical initial-boundary value problem provides specificity in the general MHD ideas presented.
A stochastic approach to the solution of magnetohydrodynamic equations
E. Floriani; R. Vilela Mendes
2011-12-09
The construction of stochastic solutions is a powerful method to obtain localized solutions in configuration or Fourier space and for parallel computation with domain decomposition. Here a stochastic solution is obtained for the magnetohydrodynamics equations. Some details are given concerning the numerical implementation of the solution which is illustrated by an example of generation of long-range magnetic fields by a velocity source.
Coupled neoclassical-magnetohydrodynamic simulations of axisymmetric plasmas
NASA Astrophysics Data System (ADS)
Lyons, Brendan C.
2014-10-01
Neoclassical effects (e.g., the bootstrap current and neoclassical toroidal viscosity [NTV]) have a profound impact on many magnetohydrodynamic (MHD) instabilities, including tearing modes, edge-localized modes (ELMs), and resistive wall modes. High-fidelity simulations of such phenomena require a multiphysics code that self-consistently couples the kinetic and fluid models. We present the first results of the DK4D code, a dynamic drift-kinetic equation (DKE) solver being developed for this application. In this study, DK4D solves a set of time-dependent, axisymmetric DKEs for the non-Maxwellian part of the electron and ion distribution functions (fNM) with linearized Fokker-Planck-Landau collision operators. The plasma is formally assumed to be in the low- to finite-collisionality regimes. The form of the DKEs used were derived in a Chapman-Enskog-like fashion, ensuring that fNM carries no density, momentum, or temperature. Rather, these quantities are contained within the background Maxwellian and are evolved by an appropriate set of extended MHD equations. We will discuss computational methods used and benchmarks to other neoclassical models and codes. Furthermore, DK4D has been coupled to a reduced, transport-timescale MHD code, allowing for self-consistent simulations of the dynamic formation of the ohmic and bootstrap currents. Several applications of this hybrid code will be presented, including an ELM-like pressure collapse. We will also discuss plans for coupling to the spatially three-dimensional, extended MHD code M3D-C1 and generalizing to nonaxisymmetric geometries, with the goal of performing self-consistent hybrid simulations of tokamak instabilities and calculations of NTV torque. This work supported by the U.S. Department of Energy (DOE) under Grant Numbers DE-FC02-08ER54969 and DE-AC02-09CH11466.
Efficient Low Dissipative High Order Schemes for Multiscale MHD Flows
NASA Technical Reports Server (NTRS)
Sjoegreen, Bjoern; Yee, Helen C.; Mansour, Nagi (Technical Monitor)
2002-01-01
Accurate numerical simulations of complex multiscale compressible viscous flows, especially high speed turbulence combustion and acoustics, demand high order schemes with adaptive numerical dissipation controls. Standard high resolution shock-capturing methods are too dissipative to capture the small scales and/or long-time wave propagations without extreme grid refinements and small time steps. An integrated approach for the control of numerical dissipation in high order schemes for the compressible Euler and Navier-Stokes equations has been developed and verified by the authors and collaborators. These schemes are suitable for the problems in question. Basically, the scheme consists of sixth-order or higher non-dissipative spatial difference operators as the base scheme. To control the amount of numerical dissipation, multiresolution wavelets are used as sensors to adaptively limit the amount and to aid the selection and/or blending of the appropriate types of numerical dissipation to be used. Magnetohydrodynamics (MHD) waves play a key role in drag reduction in highly maneuverable high speed combat aircraft, in space weather forecasting, and in the understanding of the dynamics of the evolution of our solar system and the main sequence stars. Although there exist a few well-studied second and third-order high-resolution shock-capturing schemes for the MHD in the literature, these schemes are too diffusive and not practical for turbulence/combustion MHD flows. On the other hand, extension of higher than third-order high-resolution schemes to the MHD system of equations is not straightforward. Unlike the hydrodynamic equations, the inviscid MHD system is non-strictly hyperbolic with non-convex fluxes. The wave structures and shock types are different from their hydrodynamic counterparts. Many of the non-traditional hydrodynamic shocks are not fully understood. Consequently, reliable and highly accurate numerical schemes for multiscale MHD equations pose a great challenge to algorithm development. In addition, controlling the numerical error of the divergence free condition of the magnetic fields for high order methods has been a stumbling block. Lower order methods are not practical for the astrophysical problems in question. We propose to extend our hydrodynamics schemes to the MHD equations with several desired properties over commonly used MHD schemes.
NASA-Lewis closed-cycle magnetohydrodynamics plant analysis
NASA Technical Reports Server (NTRS)
Penko, P. F.
1979-01-01
A brief review of preliminary analyses of coal fired closed cycle MHD power plants is presented. The performance of three power plants with differing combustion systems were compared. The combustion systems considered were (1) a direct coal-fired combustor, (2) a coal gasifier with in-bed desulfurization and (3) a coal gasifier requiring external fuel gas cleanup. Power plant efficiencies (auxiliary power excluded) were 44.5, 43, and 41 percent for the three plants, respectively.
NASA Astrophysics Data System (ADS)
Nicol, R.; Leonardis, E.; Chapman, S. C.; Foullon, C.
2011-12-01
Fluctuations associated with fully developed magnetohydrodynamic (MHD) turbulent flows in an infinite medium are characterized by non-Gaussian statistics which are scale invariant; this implies power law power spectra and multiscaling for the Generalized Structure Functions (GSFs). Given an observable f(r,t) and assuming statistical stationary, the p'th order moment of the GSF of the fluctuating differences <|f(r+L)-f(r)|p> scales as Lzeta(p), where L is the observation scale and ? (p) are the scaling exponents. For turbulence in a system that is of finite size, or that is not fully developed, the statistical property of scale invariance is replaced by a generalized scale invariance, or extended self- similarity (ESS), for which the various moments of the GSF have a power-law dependence on an initially unknown functions, G, such that <|f(r+L)-f(r)|p G(L)? (p). We have demonstrated [1] ESS in Ulysses in-situ observations of magnetic field fluctuations of the fast, quiet solar polar wind, and shoe that there is a single robust scaling function, G, which is anticipated to be a universal property of finite range MHD turbulent flows. However these are purely temporal observations at a single point in space. We therefore for the first time test ESS on direct measurements of the intensity field, I(r,t), associated with an imaged solar Quiescent Prominence (QP). The Solar Optical Telescope (SOT) on board Hinode provides suitable long time intervals of observation of the solar corona via images at a very high spatial and temporal resolution simultaneously. We focus on specific Ca II H-line observations of a QP which exhibits small scale up-flows with a high degree of variability suggestive of turbulence. We test self-similar properties and power-law scaling behaviour of spatio-temporal intensity fluctuations in the prominence plasma by applying GSF and ESS. We first verify that the statistics of the spatial variations of the intensity measurements are non-Gaussian. We then find power-law power spectra and evidence of ESS. By using ESS we calculate ratios of the scaling exponents ? (p), which we find are consistent with a multifractal field. Finally, we recover the dependence of the 3rd moment of the GSF for the spatial fluctuations on a function G(L) as anticipated for finite range turbulence. [1] S. C. Chapman, R. M. Nicol, Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence, Phys. Rev. Lett. 103, 241101 (2009); S. C. Chapman, R. M. Nicol, E. Leonardis, K. Kiyani, V. Carbone, Observation of universality in the generalized similarity of evolving solar wind turbulence as seen by ULYSSES, Ap. J. Letters, 695, L185, (2009)
Magnetohydrodynamic equilibrium and stability of centrifugally confined plasmas
NASA Astrophysics Data System (ADS)
Huang, Yi-Min
Centrifugal confinement is an alternative approach to magnetic fusion, employing a magnetic field with an open field line configuration. In this scheme, a plasma with magnetic mirror geometry is made to rotate azimuthally at supersonic speeds. The resulting centrifugal forces, given the field line curvature, prevent the plasma from escaping along the field lines. This dissertation addresses the equilibrium and stability of this configuration within the framework of magnetohydrodynamics (MHD). Well confined equilibrium with desirable profiles is demonstrated by numerical simulation. As far as stability is concerned, four types of magnetohydrodynamic modes determine the overall stability of centrifugally confined plasmas: flute interchanges and the Kelvin-Helmholtz instability, in a low beta system, and the magnetorotational instability (MRI) and the Parker instability, in a high beta system. One of the underpinnings of the centrifugal confinement is that flute interchanges could be stabilized by the strong velocity shear accompanying the rotation. Numerical simulations show strong evidence of stabilization, provided that the shear flow is not unstable to Kelvin-Helmholtz (KH) modes. The KH modes are ideally stable if the generalized Rayleigh's Inflexion criterion is satisfied. Particle sources are shown to be important to both equilibrium and stability. In the absence of particle sources, density profiles relax under resistive diffusion to pile up to the outboard side of the confining vessel. Tailoring the density profiles by appropriately placing the particle sources could be used to achieve control over MHD stability, for both interchanges and KH modes. Analytic analysis of interchanges based on an extension of MHD which applicable for low density plasmas with VA c is presented. The interchange growth rates are reduced by a factor of 1+V2A/c2 compared to the usual MHD prediction. The physical mechanisms of both the MRI and the Parker instability are examined and an explanation of why the MRI mechanism is insufficient to destabilize the system while the Parker instability could occur is given. Numerical simulations of the nonlinear behavior of the Parker instability are presented. It is shown that clumping from the Parker instability could reinforce centrifugal confinement.
Conceptual design of a coal-fired MHD retrofit. Final technical report
NONE
1994-06-01
Coal-fired magnetohydrodynamics (MHD) technology is ready for its next level of development - an integrated demonstration at a commercial scale. The development and testing of MHD has shown its potential to be the most efficient, least costly, and cleanest way to burn coal. Test results have verified a greater than 99% removal of sulphur with a potential for greater than 60% efficiency. This development and testing, primarily funded by the U.S. Department of Energy (DOE), has progressed through the completion of its proof-of-concept (POC) phase at the 50 MWt Component Development and Integration Facility (CDIF) and 28 MWt Coal Fired Flow Facility (CFFF), thereby, providing the basis for demonstration and further commercial development and application of the technology. The conceptual design of a retrofit coal-fired MHD generating plant was originally completed by the MHD Development Corporation (MDC) under this Contract, DE-AC22-87PC79669. Thereafter, this concept was updated and changed to a stand-alone MHD demonstration facility and submitted by MDC to DOE in response to the fifth round of solicitations for Clean Coal Technology. Although not selected, that activity represents the major interest in commercialization by the developing industry and the type of demonstration that would be eventually necessary. This report updates the original executive summary of the conceptual design by incorporating the results of the POC program as well as MDC`s proposed Billings MHD Demonstration Project (BMDP) and outlines the steps necessary for commercialization.
Lee, Ying-Ming; Simmons, G.A.; Nelson, G.L. [MSE Inc., Butte, MT (United States)
1995-12-31
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.
MHD Coal-Fired Flow Facility. Quarterly technical progress report, January-March 1980
Altstatt, M. C.; Attig, R.C. Baucum, W.E.
1980-05-30
The University of Tennessee Space Institute (UTSI) reports on significant activity, task status, planned research, testing, development, and conclusions for the Magnetohydrodynamics (MHD) Coal-Fired Flow Facility (CFFF) and the Research and Development Laboratory. Although slowed by incessant rain during several days, work on the CFFF Bid Packages progressed to nearly 100 percent completion, excluding later punchlist items. On the quench system, the cyclone separator was delivered to UTSI, and under Downstream Components, the secondary combustor was received and the radiant slagging furnace was emplaced at the CFFF. Water quality analysis of Woods Reservoir provided the expected favorable results, quite similar to last year's. Generator experiments describing local current distribution are reported along with behavior under conditions of imposed leakage. Also, during the Quarter, the shelter for the cold flow modeling facility was constructed and circuits installation begun. A jet turbine combustor was tested for use as a vitiation burner. Samples taken from the exhaust duct, besides other applications, show that the refractories used are performing well in alleviating heat loss while exhibiting acceptable degredation. A new resistive power take-off network was designed and implemented.
Magnetic Fields in Paradigms of Planetary Nebulae and Related MHD Frontiers
Eric G. Blackman
2008-12-14
Many, if not all, post AGB stellar systems swiftly transition from a spherical to a powerful aspherical pre-planetary nebula (pPNE) outflow phase before waning into a PNe. The pPNe outflows require engine rotational energy and a mechanism to extract this energy into collimated outflows. Just radiation and rotation are insufficient but a symbiosis between rotation, differential rotation and large scale magnetic fields remains promising. Present observational evidence for magnetic fields in evolved stars is suggestive of dynamically important magnetic fields, but both theory and observation are rife with research opportunity. I discuss how magnetohydrodynamic outflows might arise in pPNe and PNe and distinguish different between approaches that address shaping vs. those that address both launch and shaping. Scenarios involving dynamos in single stars, binary driven dynamos, or accretion engines cannot be ruled out. One appealing paradigm involves accretion onto the primary post-AGB white dwarf core from a low mass companion whose decaying accretion supply rate owers first the pPNe and then the lower luminosity PNe. Determining observational signatures of different MHD engines is a work in progress. Accretion disk theory and large scale dynamos pose many of their own fundamental challenges, some of which I discuss in a broader context.
Two-Fluid 2.5D MHD-Code for Simulations in the Solar Atmosphere
NASA Astrophysics Data System (ADS)
Piantschitsch, I.; Amerstorfer, U.; Thalmann, J.; Utz, D.; Hanslmeier, A.; Bárta, M.; Thonhofer, S.; Lemmerer, B.
We investigate magnetic reconnection due to the evolution of magnetic flux tubes in the solar chromosphere. We developed a new numerical two-fluid magnetohydrodynamic (MHD) code which will perform a 2.5D simulation of the dynamics from the upper convection zone up to the transition region. Our code is based on the Total Variation Diminishing Lax-Friedrichs scheme and makes use of an alternating-direction implicit method, in order to accommodate the two spatial dimensions. Since we apply a two-fluid model for our simulations, the effects of ion-neutral collisions, ionization/recombination, thermal/resistive diffusivity and collisional/resistive heating are included in the code. As initial conditions for the code we use analytically constructed vertically open magnetic flux tubes within a realistic stratified atmosphere. Initial MHD tests have already shown good agreement with known results of numerical MHD test problems like e.g. the Orszag-Tang vortex test.
H. Backes; F. M. Neubauer; M. K. Dougherty
2004-01-01
We have developed an advanced 3D model for Titan's interaction with the Saturnian magnetospheric plasma. The ideal magnetohydrodynamic (MHD) equations are extended in order to account for the effect of Titan's dense neutral atmosphere has on the plasma interaction. The ion-neutral friction plays a key role in the deceleration of the magnetospheric plasma. From the neutral atmosphere the ionosphere is
G. Vahala; Jeffrey Yepez; Min Soe; Linda Vahala; Jonathan Carter; S. Ziegler
2008-01-01
Most non-spectral computational fluid dynamics (CFD) algorithms do not scale to many thousands of cores. Here, we examine a particular mesoscopic representation of free decaying magnetohydrodynamics (MHD) turbulence that is amenable to massive parallelization to the full 9,000 cores available on Air Force Research Laboratory (AFRL) SGI Altix 4700 (Hawk). Moreover, our mesoscopic lattice Boltzmann (LB) algorithm will automatically enforce
NASA Astrophysics Data System (ADS)
Soler, Roberto; Terradas, Jaume
2015-04-01
Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.
Measurement of the Electric Fluctuation Spectrum of Magnetohydrodynamic Turbulence
Bale, S.D.; Mozer, F.S. [Department of Physics and Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States); Kellogg, P.J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Horbury, T. S. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Reme, H. [CESR, 31400 Toulouse (France)
2005-06-03
Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show the spectral behavior of classical Kolmogorov fluid turbulence over an inertial subrange and departures from this at short wavelengths, where energy should be dissipated. Here we present the first measurements of the electric field fluctuation spectrum over the inertial and dissipative wave number ranges in a {beta} > or approx. 1 plasma. The k{sup -5/3} inertial subrange is observed and agrees strikingly with the magnetic fluctuation spectrum; the wave phase speed in this regime is shown to be consistent with the Alfven speed. At smaller wavelengths k{rho}{sub i}{>=}1 the electric spectrum is enhanced and is consistent with the expected dispersion relation of short-wavelength kinetic Alfven waves. Kinetic Alfven waves damp on the solar wind ions and electrons and may act to isotropize them. This effect may explain the fluidlike nature of the solar wind.
Magnetohydrodynamics in Presence of Electric and Magnetic charges
P. S. Bisht; Pushpa; O. P. S. Negi
2010-03-15
Starting with the generalized electromagnetic field equations of dyons, we have discussed the theory of magnetohydrodynamics (MHD) of plasma for particles carrying simultaneously the electric and magnetic charges (namely dyons). It is shown that the resultant system supports the electromagnetic duality of dyons. Consequently the frequency of dyonic plasma has been obtained and it is emphasized that there is a different plasma frequency for each species depending on wave number k. For k to be real, only those generalized electromagnetic waves are allowed to pass, for which the usual frequency is greater than the plasma frequency (i.e. \\omega>\\omega_{p}). It is shown that the plasma frequency sets the lower cuts for the frequencies of electromagnetic radiation that can pass through a plasma . Accordingly the ohm's law has been reestablished to derive the plasma oscillation equation as well as the magetohydrodynamic wave equation and the energy of dyons in unique and consistent manner.
Three-dimensional force-free looplike magnetohydrodynamic equilibria
NASA Technical Reports Server (NTRS)
Finn, John M.; Guzdar, Parvez N.; Usikov, Daniel
1994-01-01
Computations of three-dimensional force-free magnetohydrodynamic (MHD) equilibria, del x B = lambdaB with lambda = lambda(sub 0), a constant are presented. These equilibria are determined by boundary conditions on a surface corresponding to the solar photosphere. The specific boundary conditions used correspond to looplike magnetic fields in the corona. It is found that as lambda(sub 0) is increased, the loops of flux become kinked, and for sufficiently large lambda(sub 0), develop knots. The relationship between the kinking and knotting properties of these equilibria and the presence of a kink instability and related loss of equilibrium is explored. Clearly, magnetic reconnection must be involved for an unknotted loop equilibrium to become knotted, and speculations are made about the creation of a closed hyperbolic field line (X-line) about which this reconnection creating knotted field lines is centered.
Magnetohydrodynamic flows in spherical shells Rainer Hollerbach
Haase, Markus
Magnetohydrodynamic flows in spherical shells Rainer Hollerbach Department of Mathematics Introduction Magnetohydrodynamics is the study of the flow of electrically conducting fluids in the presence the flow and the field that makes magnetohydrodynamics such a fascinating subject, and gives it an even
Ming Xiong; Huinan Zheng; Shui Wang
2009-01-01
The numerical studies of the interplanetary coupling between multiple magnetic clouds (MCs) are continued by a 2.5-dimensional ideal magnetohydrodynamic (MHD) model in the heliospheric meridional plane. The interplanetary direct collision (DC)\\/oblique collision (OC) between both MCs results from their same\\/different initial propagation orientations. Here the OC is explored in contrast to the results of the DC. Both the slow MC1
MHD wave interactions in space plasmas and Noether's theorem
NASA Astrophysics Data System (ADS)
Webb, G. M.
2004-09-01
The interaction of magnetohydrodynamic (MHD) waves in space plasmas can be investigated by Lagrangian and Hamiltonian methods. In this paper, we discuss the propagation of non-WKB waves in a non-uniform background plasma flow such as the solar wind, by using Lagrangian variational principles for MHD plasmas developed by Newcomb. The Lagrangian methods for the propagation of WKB waves in a non-uniform background plasma flow developed by Dewar are extended to the case of of non-WKB waves in a non-uniform background flow. As part of the analysis, we obtain Noether's theorem for the combined system of waves and background plasma. This effectively generalizes the form of Noether's theorem for Lagrangian MHD used by Padhye and Morrison and Padhye in their analysis of Lagrangian, fluid re-labelling symmetries. Examples of the use of Noether's theorem, are the derivation of the energy and momentum conservation laws for the total system of waves and background plasma, corresponding respectively to the case of time and space translation symmetries.
Very high order PNPM schemes on unstructured meshes for the resistive relativistic MHD equations
NASA Astrophysics Data System (ADS)
Dumbser, Michael; Zanotti, Olindo
2009-10-01
In this paper we propose the first better than second order accurate method in space and time for the numerical solution of the resistive relativistic magnetohydrodynamics (RRMHD) equations on unstructured meshes in multiple space dimensions. The nonlinear system under consideration is purely hyperbolic and contains a source term, the one for the evolution of the electric field, that becomes stiff for low values of the resistivity. For the spatial discretization we propose to use high order PNPM schemes as introduced in Dumbser et al. [M. Dumbser, D. Balsara, E.F. Toro, C.D. Munz, A unified framework for the construction of one-step finite volume and discontinuous Galerkin schemes, Journal of Computational Physics 227 (2008) 8209-8253] for hyperbolic conservation laws and a high order accurate unsplit time-discretization is achieved using the element-local space-time discontinuous Galerkin approach proposed in Dumbser et al. [M. Dumbser, C. Enaux, E.F. Toro, Finite volume schemes of very high order of accuracy for stiff hyperbolic balance laws, Journal of Computational Physics 227 (2008) 3971-4001] for one-dimensional balance laws with stiff source terms. The divergence-free character of the magnetic field is accounted for through the divergence cleaning procedure of Dedner et al. [A. Dedner, F. Kemm, D. Kröner, C.-D. Munz, T. Schnitzer, M. Wesenberg, Hyperbolic divergence cleaning for the MHD equations, Journal of Computational Physics 175 (2002) 645-673]. To validate our high order method we first solve some numerical test cases for which exact analytical reference solutions are known and we also show numerical convergence studies in the stiff limit of the RRMHD equations using PNPM schemes from third to fifth order of accuracy in space and time. We also present some applications with shock waves such as a classical shock tube problem with different values for the conductivity as well as a relativistic MHD rotor problem and the relativistic equivalent of the Orszag-Tang vortex problem. We have verified that the proposed method can handle equally well the resistive regime and the stiff limit of ideal relativistic MHD. For these reasons it provides a powerful tool for relativistic astrophysical simulations involving the appearance of magnetic reconnection.
MHD seed recovery and regeneration
NASA Astrophysics Data System (ADS)
1988-10-01
The TRW Econoseed MHD Seed Regeneration Process is based on the reaction of calcium formate with potassium sulfate spent seed from an MHD electric power generation plant. The process was tested at bench scale, design a proof of concept (POC) test plant, plan and cost a Phase 2 project for a POC plant evaluation and prepare a conceptual design of a 300 MW (t) commercial plant. The results of the project are as follows: (1) each of the unit operations is demonstrated, and (2) the data are incorporated into a POC plant design and project cost, as well as a 300 MW (t) commercial retrofit plant design and cost estimate. Specific results are as follows: (1) calcium formate can be produced at 100 percent yield in a total retention time of less than 5 minutes, (2) utilizing the calcium formate, spent seed can quantitatively be converted to potassium formate, potassium carbonate or mixtures of these with potassium sulfate as per the commercial design without measurable loss of potassium to insolubles at a total retention time under 20 minutes and ambient pressure, (3) the solid rejects form the process meet RCRA EP Toxicity requirements for safe disposal, and (4) filtration and evaporation data, as well as reaction data cited above, show that the Econoseed technology is ready for scale up to POC plant scale. Economics forecast studies show that the total cost per unit of potassium for seed regeneration by the Econoseed Process is in the range of $0.23 to $0.27/lb, a cost which is less than half the potassium cost of $0.63/lb for purchasing new potassium carbonate.
Klimas, A J; Paczuski, M; Klimas, Alexander J.; Uritsky, Vadim M.; Paczuski, Maya
2007-01-01
We report numerical evidence that self-organized criticality (SOC)and intermittent turbulence (IT) coexist in a current sheet model based on resistive magnetohydrodynamic (MHD) equations. The model also includes a local hysteretic switch to capture plasma physical processes outside of MHD, which are normally described as current-dependent resistivity. Results from numerical simulations show scale-free avalanches of magnetic energy dissipation characteristic of SOC, as well as multiscaling in the velocity field numerically indistinguishable from certain hierarchical turbulence theories. We argue that SOC and IT are complementary descriptions of dynamical states realized by driven current sheets -- which occur ubiquitously in astrophysical and space plasmas.
Grain Acceleration in Compressible MHD Turbulence
NASA Astrophysics Data System (ADS)
Yan, Huirong
2009-01-01
Dust sizes are affected by the grain collisions through the coagulation and shattering processes. The effects of the collisions depend on the relative velocities of grains. We discuss a new type of dust acceleration mechanism that acts in a turbulent magnetized medium. The magnetohydrodynamic (MHD) turbulence includes both fluid motions and magnetic fluctuations. While the fluid motions bring about grain motions through the drag, the electromagnetic fluctuations can accelerate grains through resonant as well as nonresonant interactions. We show that the large scale compression can accelerate dust grains provides higher velocities for a given range of scales than the process of resonance acceleration proposed in Yan & Lazarian (2003). Slow modes turbulence dominate the non-resonant acceleration. The latter was considered the dominant acceleration process in the magnetized interstellar gas. We also compare the velocities with those arising from H2 formation and the variations of the accommodation coefficient over grain surface. We discuss the consequence of the acceleration and calculate the equilibrium size distribution of grains. The implications for grain mixing, extinction curve, grain alignment, chemical abundance, etc, will be presented.
Design Study: Rocket Based MHD Generator
NASA Technical Reports Server (NTRS)
1997-01-01
This report addresses the technical feasibility and design of a rocket based MHD generator using a sub-scale LOx/RP rocket motor. The design study was constrained by assuming the generator must function within the performance and structural limits of an existing magnet and by assuming realistic limits on (1) the axial electric field, (2) the Hall parameter, (3) current density, and (4) heat flux (given the criteria of heat sink operation). The major results of the work are summarized as follows: (1) A Faraday type of generator with rectangular cross section is designed to operate with a combustor pressure of 300 psi. Based on a magnetic field strength of 1.5 Tesla, the electrical power output from this generator is estimated to be 54.2 KW with potassium seed (weight fraction 3.74%) and 92 KW with cesium seed (weight fraction 9.66%). The former corresponds to a enthalpy extraction ratio of 2.36% while that for the latter is 4.16%; (2) A conceptual design of the Faraday MHD channel is proposed, based on a maximum operating time of 10 to 15 seconds. This concept utilizes a phenolic back wall for inserting the electrodes and inter-electrode insulators. Copper electrode and aluminum oxide insulator are suggested for this channel; and (3) A testing configuration for the sub-scale rocket based MHD system is proposed. An estimate of performance of an ideal rocket based MHD accelerator is performed. With a current density constraint of 5 Amps/cm(exp 2) and a conductivity of 30 Siemens/m, the push power density can be 250, 431, and 750 MW/m(sup 3) when the induced voltage uB have values of 5, 10, and 15 KV/m, respectively.
Turbulent relaxation processes in magnetohydrodynamics
A. C. Ting; W. H. Matthaeus; D. Montgomery
1986-01-01
Competing processes previously called ''selective decay'' and ''dynamic alignment'' are studied numerically for two-dimensional magnetohydrodynamic turbulence. In selective decay, the energy decays relatively to mean-square vector potential, and in dynamic alignment, the energy decays relatively to cross helicity. In the former case, the kinetic (fluid) energy decays to zero and the magnetic energy occupies the largest scales allowed by the