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1

Magnetohydrodynamic power generation  

NASA Technical Reports Server (NTRS)

Magnetohydrodynamic (MHD) Power Generation is a concise summary of MHD theory, history, and future trends. Results of the major international MHD research projects are discussed. Data from MHD research is included. Economics of initial and operating costs are considered.

Smith, J. L.

1984-01-01

2

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant Conceptual Design Engineering Report (CDER)  

NASA Technical Reports Server (NTRS)

The reference conceptual design of the magnetohydrodynamic (MHD) Engineering Test Facility (ETF), a prototype 200 MWe coal-fired electric generating plant designed to demonstrate the commercial feasibility of open cycle MHD, is summarized. Main elements of the design, systems, and plant facilities are illustrated. System design descriptions are included for closed cycle cooling water, industrial gas systems, fuel oil, boiler flue gas, coal management, seed management, slag management, plant industrial waste, fire service water, oxidant supply, MHD power ventilating

1981-01-01

3

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant Conceptual Design Engineering Report (CDER)  

NASA Astrophysics Data System (ADS)

The reference conceptual design of the magnetohydrodynamic (MHD) Engineering Test Facility (ETF), a prototype 200 MWe coal-fired electric generating plant designed to demonstrate the commercial feasibility of open cycle MHD, is summarized. Main elements of the design, systems, and plant facilities are illustrated. System design descriptions are included for closed cycle cooling water, industrial gas systems, fuel oil, boiler flue gas, coal management, seed management, slag management, plant industrial waste, fire service water, oxidant supply, MHD power ventilating

1981-09-01

4

Parametric analysis of closed cycle magnetohydrodynamic (MHD) power plants  

NASA Technical Reports Server (NTRS)

A parametric analysis of closed cycle MHD power plants was performed which studied the technical feasibility, associated capital cost, and cost of electricity for the direct combustion of coal or coal derived fuel. Three reference plants, differing primarily in the method of coal conversion utilized, were defined. Reference Plant 1 used direct coal fired combustion while Reference Plants 2 and 3 employed on site integrated gasifiers. Reference Plant 2 used a pressurized gasifier while Reference Plant 3 used a ""state of the art' atmospheric gasifier. Thirty plant configurations were considered by using parametric variations from the Reference Plants. Parametric variations include the type of coal (Montana Rosebud or Illinois No. 6), clean up systems (hot or cold gas clean up), on or two stage atmospheric or pressurized direct fired coal combustors, and six different gasifier systems. Plant sizes ranged from 100 to 1000 MWe. Overall plant performance was calculated using two methodologies. In one task, the channel performance was assumed and the MHD topping cycle efficiencies were based on the assumed values. A second task involved rigorous calculations of channel performance (enthalpy extraction, isentropic efficiency and generator output) that verified the original (task one) assumptions. Closed cycle MHD capital costs were estimated for the task one plants; task two cost estimates were made for the channel and magnet only.

Owens, W.; Berg, R.; Murthy, R.; Patten, J.

1981-01-01

5

MHD Power Generation  

ERIC Educational Resources Information Center

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)

Kantrowitz, Arthur; Rosa, Richard J.

1975-01-01

6

Magnetohydrodynamic electromagnetic pulse (MHD-EMP) interaction with power transmission and distribution systems  

SciTech Connect

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

7

Magnetohydrodynamic electromagnetic pulse (MHD-EMP) interaction with power transmission and distribution systems  

SciTech Connect

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

8

Magnetohydrodynamic Electromagnetic Pulse (MHD-EMP) interaction with power transmission and distribution systems  

NASA Astrophysics Data System (ADS)

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.; Barnes, P. R.; Meliopoulos, A. P. S.

1992-02-01

9

Application of Magnetohydrodynamics (MHD) and Recent Research Trend  

NASA Astrophysics Data System (ADS)

As the applications of Magnetohydrodynamic (MHD) energy conversion, research and development for high-efficiency and low emission electric power generation system, MHD accelerations and/or MHD thrusters, and flow control around hypersonic and re-entry vehicles are introduced. For closed cycle MHD power generation, high-efficiency MHD single system is the most hopeful system and space power system using mixed inert gas (MIG) working medium is proposed. For open cycle MHD, high-efficiency coal fired MHD system with CO2 recovery has been proposed. As inverse process of MHD power generation, MHD accelerators/thrusters are expected as the next generation propulsion system. Heat flux reduction to protect re-entry vehicles is expected by an MHD process for safety return from space missions.

Harada, Nobuhiro

10

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Design Requirements Document (DRD)  

NASA Technical Reports Server (NTRS)

A description and the design requirements for the 200 MWe (nominal) net output MHD Engineering Test Facility (ETF) Conceptual Design, are presented. Performance requirements for the plant are identified and process conditions are indicated at interface stations between the major systems comprising the plant. Also included are the description, functions, interfaces and requirements for each of these major systems. The lastest information (1980-1981) from the MHD technology program are integrated with elements of a conventional steam electric power generating plant.

Rigo, H. S.; Bercaw, R. W.; Burkhart, J. A.; Mroz, T. S.; Bents, D. J.; Hatch, A. M.

1981-01-01

11

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER). Volume 4: Supplementary engineering data  

NASA Technical Reports Server (NTRS)

The reference conceptual design of the Magnetohydrodynamic Engineering Test Facility (ETF), a prototype 200 MWe coal-fired electric generating plant designed to demonstrate the commercial feasibility of open cycle MHD is summarized. Main elements of the design are identified and explained, and the rationale behind them is reviewed. Major systems and plant facilities are listed and discussed. Construction cost and schedule estimates, and identification of engineering issues that should be reexamined are also given. The latest (1980-1981) information from the MHD technology program are integrated with the elements of a conventional steam power electric generating plant. Supplementary Engineering Data (Issues, Background, Performance Assurance Plan, Design Details, System Design Descriptions and Related Drawings) is presented.

1981-01-01

12

Magnetohydrodynamics MHD Engineering Test Facility ETF 200 MWe power plant. Conceptual Design Engineering Report CDER. Volume 3: Costs and schedules  

NASA Technical Reports Server (NTRS)

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.

1981-01-01

13

An innovative demonstration of high power density in a compact MHD (magnetohydrodynamic) generator  

SciTech Connect

The present program was conducted by the University of Tennessee Space Institute (UTSI). It was by its nature a high risk experimental program to demonstrate the feasibility of high power density operation in a laboratory scale combustion driven MHD generator. Maximization of specific energy was not a consideration for the present program, but the results have implications in this regard by virtue of high energy fuel used. The power density is the ratio of the electrical energy output to the internal volume of the generator channel. The MHD process is a volumetric process and the power density is therefore a direct measure of the compactness of the system. Specific energy, is the ratio of the electrical energy output to consumable energy used for its production. The two parameters are conceptually interrelated. To achieve high power density and implied commensurate low system volume and weight, it was necessary to use an energetic fuel. The high energy fuel of choice was a mixture of powdered aluminum and carbon seeded with potassium carbonate and burned with gaseous oxygen. The solid fuel was burned in a hybrid combustion scheme wherein the fuel was cast within a cylindrical combustor in analogy with a solid propellant rocket motor. Experimental data is limited to gross channel output current and voltage, magnetic field strength, fuel and oxidizer flow rates, flow train external temperatures and combustor pressure. Similarly, while instantaneous oxidizer flow rates were measured, only average fuel consumption based on pre and post test component weights and dimensions was possible. 4 refs., 60 figs., 9 tabs.

Schmidt, H.J.; Lineberry, J.T.; Chapman, J.N.

1990-06-01

14

Magnetohydrodynamic (MHD) channel corner seal  

DOEpatents

A corner seal for an MHD duct includes a compressible portion which contacts the duct walls and an insulating portion which contacts the electrodes, sidewall bars and insulators. The compressible portion may be a pneumatic or hydraulic gasket or an open-cell foam rubber. The insulating portion is segmented into a plurality of pieces of the same thickness as the electrodes, insulators and sidewall bars and aligned therewith, the pieces aligned with the insulator being of a different size from the pieces aligned with the electrodes and sidewall bars to create a stepped configuration along the corners of the MHD channel.

Spurrier, Francis R. (Pittsburgh, PA)

1980-01-01

15

Concept to Employ Magnetohydrodynamic (MHD) Conversion in a 2 GW Direct Drive Inertial Fusion Energy (IFE) Power Reactor  

NASA Astrophysics Data System (ADS)

The conceptual design of a 2 GW direct drive IFE power reactor may provide an opportunity to directly harness the power in the post detonation ion fields. Conceptually, this can be accomplished by utilizing a magnetic cusp field to guide the ions into equatorial and polar ion dumps. The ion fields resulting from this magnetic intervention configuration pose a distinct challenge, as their intensity may have the potential to damage the ion dumps. One method of addressing this challenge is by employing MHD conversion to transform the internal energy of the fields directly into electrical energy, a process which would also reduce the fields' strength. In order to analyze the potential of MHD conversion in IFE, results of previous work in other applications are examined in the context of this project. Preliminary assessment reveals that MHD conversion is a promising solution to this issue, although a number of engineering and practical concerns will need to be addressed. This paper concentrates on the primary issues associated with MHD conversion. Support for this research was provided by the U.S. Department of Energy's Science Undergraduate Laboratory Internship (SULI) Program.

Anderson, Brett; Burstein, Alison; Gentile, Charles

2007-11-01

16

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER). Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

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.

1981-01-01

17

Explosively-driven magnetohydrodynamic (MHD) generator studies  

SciTech Connect

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.

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

18

Mesofluidic magnetohydrodynamic power generation  

E-print Network

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 ...

Fucetola, Jay J

2012-01-01

19

Performance characteristics of an MHD (Magnetohydrodynamic) pilot plant electrostatic precipitator  

NASA Astrophysics Data System (ADS)

In magnetohydrodynamic (MHD) power generation, a seed material, normally K2CO3, is added to enhance the conductivity of the coal-fired gas stream. The plasma is passed through a magnetic field and electricity is produced by the Hall effect. Future large scale MHD facilities are expected to be more efficient than conventional coal-fired power plants not only because of the dc electricity produced but also from increased heat recovery owing to the large (3000 K) combustion temperatures employed. There is; however, a finite cost for the seed material and the resulting K2SO4 particles (SO2 emissions are minimized by combination with seed potassium) must be collected, converted back to K2CO3 or KCO2H, and recycled back to the combustor. The performance characteristics of the MHD electrostatic precipitator (ESP) are therefore, of interest. We describe Mie scattering and electric field measurements on an MHD pilot scale ESP located at the Coal Fire Flow Facility (CFFF) at the University of Tennessee Space Institute. Results are reported for the determination of near-real-time collection efficiencies, the variation of the ESP performance with seed percentage, and initial studies on the extent of particle re-entrainment.

Lindner, J. S.; Jang, P. R.; Okhuysen, W. P.; Holt, J. K.

20

Magnetohydrodynamic flows and performance characteristics of the MHD pump  

Microsoft Academic Search

Numerical Analyses on sea-water-MHD-propulsion with a small interaction parameter and liquid-metal-MHD-pump with a intermediate interaction parameter are carried out. For the above two cases, the ways of non dimension of pressure variable are different from each other; therefore, non dimension equations and boundary conditions are also different from each other. Numerical investigation on steady-state, three-dimensional, incompressible, magnetohydrodynamic flows including viscosity

Chang-Nyung Kim

1994-01-01

21

FLIP MHD: A particle-in-cell method for magnetohydrodynamics  

Microsoft Academic Search

A particle-in-cell (PIC) method, FLIP is extended to magnetohydrodynamic (MHD) flow in two dimensions. Particles are used to reduce computational diffusion of the magnetic field. FLIP is an extension of classical'' PIC, where particles have mass, but every other property of the fluid is stored on a grid. In FLIP, particles have every property of the fluid, so that they

J. Brackbill

1990-01-01

22

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER). Volume 2: Engineering. Volume 3: Costs and schedules  

NASA Technical Reports Server (NTRS)

Engineering design details for the principal systems, system operating modes, site facilities, and structures of an engineering test facility (ETF) of a 200 MWE power plant are presented. The ETF resembles a coal-fired steam power plant in many ways. It is analogous to a conventional plant which has had the coal combustor replaced with the MHD power train. Most of the ETF components are conventional. They can, however, be sized or configured differently or perform additional functions from those in a conventional coal power plant. The boiler not only generates steam, but also performs the functions of heating the MHD oxidant, recovering seed, and controlling emissions.

1981-01-01

23

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER). Volume 2: Engineering. Volume 3: Costs and schedules  

NASA Astrophysics Data System (ADS)

Engineering design details for the principal systems, system operating modes, site facilities, and structures of an engineering test facility (ETF) of a 200 MWE power plant are presented. The ETF resembles a coal-fired steam power plant in many ways. It is analogous to a conventional plant which has had the coal combustor replaced with the MHD power train. Most of the ETF components are conventional. They can, however, be sized or configured differently or perform additional functions from those in a conventional coal power plant. The boiler not only generates steam, but also performs the functions of heating the MHD oxidant, recovering seed, and controlling emissions.

1981-09-01

24

MHD I: Demonstrate Magnetohydrodynamic Propulsion in a Minute  

NSDL National Science Digital Library

Remember the silent caterpillar drive from the movie The Hunt for Red October? The caterpillar drive was a fictional magnetohydrodynamic propulsion system. Magnetohydrodynamic (MHD) propulsion is a means of using electrical current, instead of a noisy propeller, to push a ship through the water. Surprisingly enough, a working example of this futuristic drive system is quite easy to build. Assuming that you've got the materials handy, you can build one in about a minute. This is a great student project or a good demonstration.

25

Electroosmosis and thermal effects in magnetohydrodynamic (MHD) micropumps using 3D MHD equations  

Microsoft Academic Search

Magnetohydrodynamics (MHD) micropumps which have no moving parts have attracted attention from the microfluidics community. A signifi- cant amount of research is being reported in the design, fabrication and operation of such devices. In this work, we report analytical investigation of the physics of such devices and a development of a generalized numerical framework for the solution of the full

Vaibhav Patel; Samuel Kinde Kassegne

2006-01-01

26

Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER) supplement. Magnet system special investigations  

NASA Technical Reports Server (NTRS)

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.

1981-01-01

27

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 9: Closed-cycle MHD. [energy conversion efficiency of electric power plants using magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

A closed-cycle MHD system for an electric power plant was studied. It consists of 3 interlocking loops, an external heating loop, a closed-cycle cesium seeded argon nonequilibrium ionization MHD loop, and a steam bottomer. A MHD duct maximum temperature of 2366 K (3800 F), a pressure of 0.939 MPa (9.27 atm) and a Mach number of 0.9 are found to give a topping cycle efficiency of 59.3%; however when combined with an integrated gasifier and optimistic steam bottomer the coal to bus bar efficiency drops to 45.5%. A 1978 K (3100 F) cycle has an efficiency of 55.1% and a power plant efficiency of 42.2%. The high cost of the external heating loop components results in a cost of electricity of 21.41 mills/MJ (77.07 mills/kWh) for the high temperature system and 19.0 mills/MJ (68.5 mills/kWh) for the lower temperature system. It is, therefore, thought that this cycle may be more applicable to internally heated systems such as some futuristic high temperature gas cooled reactor.

Tsu, T. C.

1976-01-01

28

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 8: Open-cycle MHD. [energy conversion efficiency and design analysis of electric power plants employing magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

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.

Hoover, D. Q.

1976-01-01

29

Simulation of a seawater MHD power generation system  

NASA Astrophysics Data System (ADS)

MHD (magnetohydrodynamics) power generation systems are expected to become popular with the development of superconducting technology because of their low cost and high efficiency. MHD power generation directly utilizes electromotive force, which arises when seawater crosses a magnetic field. The helical-type MHD generator is composed mainly of a helical partition board and electrodes, which include a cathode pipe on the exterior of the generator and an anode rod in the interior. Elementary research on a helical-type MHD power generation system has started at Kobe University, and a numerical simulation of the system has been carried out by FEM (Finite Element Method) at the National Institute for Materials Science. By comparing the simulation results with the theoretical and experimental results, we found that the proposed method is valid for simulating the MHD power generation system.

Liu, Xiaojun; Kiyoshi, Tsukasa; Takeda, Minoru

2006-05-01

30

The Galerkin boundary node method for magneto-hydrodynamic (MHD) equation  

NASA Astrophysics Data System (ADS)

In this research, a variational reformulation for magneto-hydrodynamic (MHD) problem is derived. Existence and uniqueness of the weak solution are discussed. The Galerkin boundary node method is a boundary meshless method which uses MLS basis functions to approximate solution of problems. This paper tries to apply this method for a variational form of the magneto-hydrodynamic (MHD) problem. Numerical experiments reveal that the method is effective and convenient for this problem.

Tatari, Mehdi; Ghasemi, Fatemeh

2014-02-01

31

The optimization air separation plants for combined cycle MHD-power plant applications  

NASA Technical Reports Server (NTRS)

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 combined cycle power plants.

Juhasz, A. J.; Springmann, H.; Greenberg, R.

1980-01-01

32

Laser-powered MHD generators for space application  

NASA Technical Reports Server (NTRS)

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.

Jalufka, N. W.

1986-01-01

33

Laser-powered MHD generators for space application  

SciTech Connect

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.

Jalufka, N.W.

1986-10-01

34

Magnetohydrodynamic Power Generation in the Laboratory Simulated Martian Entry Plasma  

NASA Technical Reports Server (NTRS)

This paper addresses the magnetohydrodynamic (MHD) conversion of the energy released during the planetary entry phase of an interplanetary vehicle trajectory. The effect of MHD conversion is multi-fold. It reduces and redirects heat transferred to the vehicle, and regenerates the dissipated energy in reusable and transportable form. A vehicle on an interplanetary mission carries about 10,000 kWh of kinetic energy per ton of its mass. This energy is dissipated into heat during the planetary atmospheric entry phase. For instance, the kinetic energy of Mars Pathfinder was about 4220 kWh. Based on the loss in velocity, Mars Pathfinder lost about 92.5% of that energy during the plasma-sustaining entry phase that is approximately 3900 kWh. An ideal MHD generator, distributed over the probe surface of Mars Pathfinder could convert more than 2000 kWh of this energy loss into electrical energy, which correspond to more than 50% of the kinetic energy loss. That means that the heat transferred to the probe surface can be reduced by at least 50% if the converted energy is adequately stored, or re-radiated, or directly used. Therefore, MHD conversion could act not only as the power generating, but also as the cooling process. In this paper we describe results of preliminary experiments with light and microwave emitters powered by model magnetohydrodynamic generators and discuss method for direct use of converted energy.

Vuskovic, L.; Popovic, S.; Drake, J.; Moses, R. W.

2005-01-01

35

Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power  

NASA Technical Reports Server (NTRS)

The prospects for realizing an integrated pulse detonation propulsion and magnetohydrodynamic (MHD) power system are examined. First, energy requirements for direct detonation initiation of various fuel-oxygen and fuel-air mixtures are deduced from available experimental data and theoretical models. Second, the pumping power requirements for effective chamber scavenging are examined through the introduction of a scavenging ratio parameter and a scavenging efficiency parameter. A series of laboratory experiments were carried out to investigate the basic engineering performance characteristics of a pulse detonation-driven MHD electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube confirmed the attainment of detonation conditions (p(sub 2)/p(sub 1) approx. 34 and D approx. 2,400 m/sec) and enabled the direct measurement of current density and electrical conductivity (=6 S/m) behind the detonation wave front. In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was inserted in applied magnetic fields of 0.6 and 0.95 T. and the electrodes were connected to an active loading circuit to characterize power extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 Ohm. The measured power density was in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. The time-resolved thrust characteristics of the system were also measured, and it was found that the MHD interaction exerted a negligible influence on system thrust and that the measured I(sub sp) of the system (200 sec) exceeded that computed for an equivalent nozzleless rocket (120 sec).

Litchford, R. J.; Lyles, Garry M. (Technical Monitor)

2001-01-01

36

Investigations for biogas operated MHD power generators  

SciTech Connect

Biogas is produced from the anaerobic fermentation of the organic matter containing cellulose, such as agricultural wastes, human wastes, animal wastes, etc. It contains methane (50-70%), carbon dioxide (30-50%), and very small amounts of hydrogen and hydrogen sulphide. Adequate quantities of raw material to generate biogas are normally available in rural areas, and therefore, there is a possibility that almost all the energy requirements of the rural sector may be fulfilled by biogas. Presently in the rural sector, biogas is used mainly to provide thermal energy (for cooking, etc.), and up to a limited extent, to meet the electrical energy requirements by running electrical generators with engines powered by a mixture of oil and biogas. In this paper, the authors propose a scheme in which biogas can be used to generate electricity more efficiently by using magnetohydrodynamic (MHD) power generators. Investigations have been carried out to make feasibility studies for biogas-operated open cycle MHD power generators. Composition, temperature and electrical conductivity of the seeded (with potassium) combustion products of biogas-air/oxygen systems have been analytically investigated for different percentages of CO/sub 2/ in biogas and at various combustor pressures for a seeding ratio of 1 percent by weight. The effect of preheating and enrichment of air on temperature and electrical conductivity of the seeded combustion plasmas has also been studied.

Dahiya, R.P.; Chand, A.; Sharma, S.C.

1983-12-01

37

Magnetohydrodynamic (MHD) nuclear weapons effects on submarine cable systems. Volume 1. Experiments and analysis. Final report  

SciTech Connect

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.

Not Available

1987-06-01

38

Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power  

NASA Technical Reports Server (NTRS)

The prospects for realizing an integrated pulse detonation propulsion and magnetohydrodynamic (MHD) power system are examined. First, energy requirements for direct detonation initiation of various fuel-oxygen and fuel-air mixtures are deduced from available experimental data and theoretical models. Second, the pumping power requirements for effective chamber scavenging are examined through the introduction of a scavenging ratio parameter and a scavenging efficiency parameter. A series of laboratory experiments were carried out to investigate the basic engineering performance characteristics of a pulse detonation-driven MHD electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube confirmed the attainment of detonation conditions (p2/p1 approximately 34 and D approximately 2,400 m/sec) and enabled the direct measurement of current density and electrical conductivity (approximately = 6 S/m) behind the detonation wave front, In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was inserted in applied magnetic fields of 0.6 and 0.95 T, and the electrodes were connected to an active loading circuit to characterize power extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 Omega. The measured power density was in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. The time-resolved thrust characteristics of the system were also measured, and it was found that the NM interaction exerted a negligible influence on system thrust and that the measured I(sub sp) of the system (200 see) exceeded that computed for an equivalent nozzleless rocket (120 see).

Litchford, Ron J.

2001-01-01

39

FLIP-MHD: A particle-in-cell method for magnetohydrodynamics  

Microsoft Academic Search

A particle-in-cell (PIC) method, FLIP is extended to magnetohydrodynamic (MHD) flow in two dimensions. Particles are used to reduce computational diffusion of the magnetic field. FLIP is an extension of classical PIC, where particles have mass, but every other property of the fluid is stored on a grid. In FLIP, particles have every property of the fluid, so that they

J. U. Brackbill

1990-01-01

40

FLIP MHD - A particle-in-cell method for magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

The fluid-implicit-particle, or 'FLIP' method presently extended to 2D and 3D MHD flow incorporates a Lagrangian field representation and yields a grid magnetic Reynolds number of up to 16 while preserving contact continuities that retain the Galilean invariance of the MHD flow equations. Analytical arguments and numerical examples demonstrate the conservation of mass, momentum, magnetic flux, and energy; 2D calculation results for the illustrative cases of contact discontinuity convection, Rayleigh-Taylor unstable flow.

Brackbill, J. U.

1991-01-01

41

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 10: Liquid-metal MHD systems. [energy conversion efficiency of electric power plants using liquid metal magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

Electric Power Plant costs and efficiencies are presented for two basic liquid-metal cycles corresponding to 922 and 1089 K (1200 and 1500 F) for a commercial applications using direct coal firing. Sixteen plant designs are considered for which major component equipment were sized and costed. The design basis for each major component is discussed. Also described is the overall systems computer model that was developed to analyze the thermodynamics of the various cycle configurations that were considered.

Holman, R. R.; Lippert, T. E.

1976-01-01

42

Theoretical MHD (magnetohydrodynamic) simulations of coronal transients and interplanetary observations  

Microsoft Academic Search

A major long-range goal of theoretical simulations of solar-generated disturbances (transients, coronal holes, etc.) is the realistic modeling of a propagating disturbance from the sun into and throughout interplanetary space. Simulations of this kind, using MHD fluid theory, must always be confronted with observations in order to assess the degree to which one or the other is inadequate. We describe

M. Dryer; R. S. Steinolfson; Z. K. Smith

1982-01-01

43

National program for MHD power generation  

Microsoft Academic Search

Development of MHD power generation systems in the U.S. is reviewed, with attention given to testing of MHD channels and electrodes, the use of high-temperature corrosion\\/erosion resistant materials for MHD components, and the Engineering Test Facility to be built under ERDA sponsorship in Montana. The current emphasis of the U.S. program is on the generation of electric power through utilization

W. D. Jackson; R. V. Shanklin; P. S. Zygielbaum

1976-01-01

44

Magnetohydrodynamic research program of the MHD Energy center at Mississippi State University and structural features of MHD radiant boilers  

NASA Astrophysics Data System (ADS)

Magnetohydrodynamic is conducted largerly through use of test stand which simulates conditions in the MHD gas stream. Continual modification of the test stand to reflect experimental results produced a test stand capable of test runs of 100 hours; runs of more than 500 hours are planned. The test stand is described, and experimental results are discussed. The design and construction of MHD radiant boiler are described. The radiant furnance serves several functions in a heat recovery and seed recovery system; it cools flue gases to a temperature suitable for entrance to the secondary superheater; it generates steam; it provides for the removal of molten ash at high temperatures; and it provides access for intrusive and nonintrusive instrumentation to the gas-side environment.

Shepard, W. S.

45

Pulse Detonation Rocket MHD Power Experiment  

NASA Technical Reports Server (NTRS)

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.

Litchford, Ron J.; Cook, Stephen (Technical Monitor)

2002-01-01

46

Sialon Electrodes and Insulators for MHD Device  

NASA Technical Reports Server (NTRS)

Rectangular magnetohydrodynamic (MHD) channel structure for electrical power generation designed using pure sialon ceramic for insulating portion of structure and metal-bearing sialon cermet for conducting portion.

Phillips, W. M.

1984-01-01

47

The Effect of Magnetohydrodynamic (MHD) Energy Bypass on Specific Thrust for a Supersonic Turbojet Engine  

NASA Technical Reports Server (NTRS)

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.

Benyo, Theresa L.

2010-01-01

48

MHD (magnetohydrodynamic) undersea propulsion: A novel concept with renewed interest  

SciTech Connect

This paper discusses the reasons for the national and international renewed interest in the concept of MHD seawater propulsion. The main advantages of this concept are presented, together with some of the technical challenges that need to be overcome to achieve reliability, performance, and stealth. The paper discusses in more detail some of the technical issues and loss mechanisms influencing the thruster performance in terms of its electrical efficiency. Among the issues discussed are the jet losses and nozzle efficiency. Ohmic losses and frictional losses inside the thruster. Also discussed are the electrical end losses caused by the fringing magnetic field near the end of the electrodes. It has been shown that the frictional and end losses can have strong adverse effects on the thruster performance. Furthermore, a parametric study has been performed to investigate the effects of several parameters on the performance of the MHD thrusters. Those parameters include the magnetic field, thruster diameter, all roughness, flow velocity, and electrical load factor. The results of the parametric study indicate that the thruster efficiency increases with the strength of the magnetic field and thruster diameter, and decreases with the wall roughness and the flow velocity. 8 refs., 8 figs.

Doss, E.D.; Geyer, H.K. (Argonne National Lab., IL (USA)); Roy, G.D. (Office of Naval Research, Arlington, VA (USA))

1990-01-01

49

WhiskyMHD: Numerical Code for General Relativistic Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Whisky is a code to evolve the equations of general relativistic hydrodynamics (GRHD) and magnetohydrodynamics (GRMHD) in 3D Cartesian coordinates on a curved dynamical background. It was originally developed by and for members of the EU Network on Sources of Gravitational Radiation and is based on the Cactus Computational Toolkit. Whisky can also implement adaptive mesh refinement (AMR) if compiled together with Carpet. Whisky has grown from earlier codes such as GR3D and GRAstro_Hydro, but has been rewritten to take advantage of some of the latest research performed here in the EU. The motivation behind Whisky is to compute gravitational radiation waveforms for systems that involve matter. Examples would include the merger of a binary system containing a neutron star, which are expected to be reasonably common in the universe and expected to produce substantial amounts of radiation. Other possible sources are given in the projects list.

Baiotti, Luca; Giacomazzo, Bruno; Hawke, Ian; et al.

2010-10-01

50

A design for an MHD power plant as a prime mover for a Naval Vessel  

Microsoft Academic Search

A Magnetohydrodynamic Power Plant, designed to be the prime mover for a Naval Vessel, is presented. The system is an open cycle, fossil fueled, subsonic MHD Faraday generator with directly fired air preheaters. A superconducting electric transmission drives the propellers and a standard naval steam plant is used as a bottoming cycle. The increased overall efficiency achievable with this plant

M. A. Paluszek

1981-01-01

51

Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal  

SciTech Connect

Poloidal rotation is routinely observed in present-day tokamak experiments, in particular near the plasma edge and in the high-confinement mode of operation. According to the magnetohydrodynamic (MHD) equilibrium theory [R. Betti and J. P. Freidberg, Phys. Plasmas 7, 2439 (2000)], radial discontinuities form when the poloidal velocity exceeds the poloidal sound speed (or rather, more correctly, the poloidal magneto-slow speed). Two-dimensional compressible magnetohydrodynamic simulations show that the transonic discontinuities develop on a time scale of a plasma poloidal revolution to form an edge density pedestal and a localized velocity shear layer at the pedestal location. While such an MHD pedestal surrounds the entire core, the outboard side of the pedestal is driven by the transonic discontinuity while the inboard side is caused by a poloidal redistribution of the mass. The MHD simulations use a smooth momentum source to drive the poloidal flow. Soon after the flow exceeds the poloidal sound speed, the density pedestal and the velocity shear layer form and persist into a quasi steady state. These results may be relevant to the L-H transition, the early stages of the pedestal and edge transport barrier formation.

Guazzotto, L. [Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States); Betti, R. [Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)

2011-09-15

52

FLIP-MHD: A particle-in-cell method for magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

A particle-in-cell (PIC) method, FLIP is extended to magnetohydrodynamic (MHD) flow in two dimensions. Particles are used to reduce computational diffusion of the magnetic field. FLIP is an extension of classical PIC, where particles have mass, but every other property of the fluid is stored on a grid. In FLIP, particles have every property of the fluid, so that they provide a complete Lagrangian description not only to resolve contact discontinuities but also to reduce computational diffusion of linear and angular momentum. The interactions among the particles are calculated on a grid, for convenience and economy. The present study extends FLIP to MHD, by including information about the magnetic field among the attributes of the particles.

Brackbill, J. U.

53

Energy exchange and wave action conservation for magnetohydrodynamic (MHD) waves in a general, slowly varying medium  

NASA Astrophysics Data System (ADS)

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.

Walker, A. D. M.

2014-12-01

54

Simulation of high-frequency solar wind power spectra using Hall magnetohydrodynamics  

Microsoft Academic Search

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

S. Ghosh; E. Siregar; D. A. Roberts; M. L. Goldstein

1996-01-01

55

Solar driven liquid metal MHD power generator  

NASA Technical Reports Server (NTRS)

A solar energy collector focuses solar energy onto a solar oven which is attached to a mixer which in turn is attached to the channel of a MHD generator. Gas enters the oven and a liquid metal enters the mixer. The gas/liquid metal mixture is heated by the collected solar energy and moves through the MHD generator thereby generating electrical power. The mixture is then separated and recycled.

Lee, J. H.; Hohl, F. (inventors)

1983-01-01

56

ON THE PROSPECT OF EMPLOYING MAGNETOHYDRODYNAMIC GENERATORS FOR SHIP PROPULSION  

Microsoft Academic Search

The basic features of magnetohydrodynamic (MHD) power generating units ; are discussed with a view to their utilization for ship propulsion. Theoretical ; principles of a magnetohydrodynamic generator are displayed. It is pointed out ; that the MHD method of power generation makes it possible to use fuel gas at much ; higher temperatures than in gas turbines, and thus

G. A. Matveev; P. D. Ivanov

1962-01-01

57

Design for an MHD power plant as a prime mover for a Naval Vessel  

SciTech Connect

A Magnetohydrodynamic Power Plant, designed to be the prime mover for a Naval Vessel, is presented. The system is an open cycle, fossil fueled, subsonic MHD Faraday generator with directly fired air preheaters. A superconducting electric transmission drives the propellers and a standard naval steam plant is used as a bottoming cycle. The increased overall efficiency achievable with this plant allows a lighter, smaller volume ship to accommodate the same payload and reduces the overall fuel cost of the vessel.

Paluszek, M.A.

1981-01-01

58

A design for an MHD power plant as a prime mover for a Naval Vessel  

NASA Astrophysics Data System (ADS)

A Magnetohydrodynamic Power Plant, designed to be the prime mover for a Naval Vessel, is presented. The system is an open cycle, fossil fueled, subsonic MHD Faraday generator with directly fired air preheaters. A superconducting electric transmission drives the propellers and a standard naval steam plant is used as a bottoming cycle. The increased overall efficiency achievable with this plant allows a lighter, smaller volume ship to accommodate the same payload and reduces the overall fuel cost of the vessel.

Paluszek, M. A.

1981-12-01

59

Heating the Intracluster Medium: Magnetohydrodynamic (MHD) Simulations of Shock/Bubble Rotational Heating  

NASA Astrophysics Data System (ADS)

Recent observations of galaxy clusters show that temperatures of the intracluster medium (ICM) lie in the range of 10-100 million K. We would expect this gas to cool via radiative cooling; however, we do not observe this cooling. One way of keeping the ICM hot involves the coupling of jets emanating from supermassive black holes at the centers of galaxies within the cluster with the ICM. The energies involved in the bubbles that these jets inflate in the ICM can provide sufficient energy to heat the gas. However, we do not know how the jet energy becomes thermalized; we present a mechanism that will thermalize the jet energy. The jets have a duty cycle which can cause a shock wave to run across a previously inflated underdense bubble in the ICM. The resulting instability (Richtmyer-Meshkov) causes energy from the shock/jet to transform into rotational kinetic energy, which can then thermalize through turbulence and viscosity. We present the results of shock/bubble interactions with 2D and 3D hydrodynamic and magnetohydrodynamic (MHD) simulations.

Friedman, Samuel H.; Heinz, S.

2010-01-01

60

MHD advanced power train. Phase 1, Final report: Volume 3, Power train system description and specification for 200MWe Plant  

SciTech Connect

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.

Jones, A.R.

1985-08-01

61

Flow simulation of the Component Development Integration Facility magnetohydrodynamic power train system  

SciTech Connect

This report covers application of Argonne National Laboratory`s (ANL`s) computer codes to simulation and analysis of components of the magnetohydrodynamic (MHD) power train system at the Component Development and Integration Facility (CDIF). Major components of the system include a 50-MWt coal-fired, two-stage combustor and an MHD channel. The combustor, designed and built by TRW, includes a deswirl section between the first and the second-stage combustor and a converging nozzle following the second-stage combustor, which connects to the MHD channel. ANL used computer codes to simulate and analyze flow characteristics in various components of the MHD system. The first-stage swirl combustor was deemed a mature technology and, therefore, was not included in the computer simulation. Several versions of the ICOMFLO computer code were used for the deswirl section and second-stage combustor. The MGMHD code, upgraded with a slag current leakage submodel, was used for the MHD channel. Whenever possible data from the test facilities were used to aid in calibrating parameters in the computer code, to validate the computer code, or to set base-case operating conditions for computations with the computer code. Extensive sensitivity and parametric studies were done on cold-flow mixing in the second-stage combustor, reacting flow in the second-stage combustor and converging nozzle, and particle-laden flow in the deswirl zone of the first-stage combustor, the second-stage combustor, and the converging nozzle. These simulations with subsequent analysis were able to show clearly in flow patterns and various computable measures of performance a number of sensitive and problematical areas in the design of the power train. The simulations of upstream components also provided inlet parameter profiles for simulation of the MHD power generating channel. 86 figs., 18 tabs.

Chang, S.L.; Lottes, S.A.; Bouillard, J.X.; Petrick, M.

1997-11-01

62

Effective method for MHD retrofit of power plants  

SciTech Connect

Retrofitting existing power plants with an open-cycle MHD system has been re-examined in light of recent developments in the heat and seed recovery technology area. A new retrofit cycle configuration has been developed which provides for a direct gas-gas coupling; also, the MHD topping cycle can be decoupled from the existing plant for either separate or joint operation. As an example, the MHD retrofit concept has been applied to Illinois Power Company's Vermilion Station No. 1, a coal-fired power plant presently in operation. Substantial increases in efficiency have been demonstrated and the economic validity of the MHD retrofit approach has been established.

Berry, G.F.; Dennis, C.B.; Johnson, T.R.; Minkov, V.

1981-10-01

63

Power facility with a built-in multipolar MHD generator  

SciTech Connect

The scheme of a power facility with a built-in multipolar MHD generator is discussed. In most papers devoted to airborne high-power MHD generators (self-contained or built into the nozzle of the propulsion unit), MHD channels are discussed that are based on a two-pole scheme. The processes of energy conversion in these MHD generators are usually accompanied by disturbances of flow in the entire channel volume, which, in many cases, is undesirable for the operation of power facilities. Depending on the number of pairs of poles, the proposed facility makes it possible to accomplish MHD conversion both in the nozzle peripheral zone and in the central part of the flow. An analysis of the methods and results of calculations of volume MHD effects for finite Hall parameters {beta} and MHD-interaction s, as well as of the output characteristics of multipolar MHD generators equipped with electrode modules of different types are given. A comparison of the theoretical and experimental data is made. A scheme involving an advanced propulsion unit fired with cryogenic fuel H{sub 2}+O{sub 2} and a built-in multipolar MHD generator is considered. The problems of using built-in multipolar MHD generators in propulsion units utilizing other fuel pairs are discussed.

Kovalev, K.L.; Markina, T.A. [Moscow Aviation Institute, Moscow (Russian Federation)

1995-05-01

64

Analytical and computational investigations of a magnetohydrodynamics (MHD) energy-bypass system for supersonic gas turbine engines to enable hypersonic flight  

NASA Astrophysics Data System (ADS)

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

Benyo, Theresa Louise

65

Magnetohydrodynamic projects at the CDIF  

NASA Astrophysics Data System (ADS)

The Component Development and Integration Facility (CDIF) is a major U.S. Department of Energy magnetohydrodynamics (MHD) test facility in Butte, Montana. The CDIF is operated by MSE, Inc. Within the national MHD program, MSE personnel are responsible for performing integration testing of vendor-supplied MHD power train components at the CDIF to support the goal of commercialization. During the second quarter of FY-92, a second external water leak on the iron-core magnet was repaired, and MHD testing was completed on 11 Feb.; this was the final testing of the workhorse hardware. Workhorse hardware was removed, and installation of the proof-of-concept (POC) combustor began.

66

Performance analysis of seawater magnetohydrodynamics (MHD) thruster propulsion systems within a test loop  

Microsoft Academic Search

The recent dramatic development in high temperatures superconducting materials and the successful operation of large and sophisticated magnet systems make it desirable to further develop the MHD seawater propulsion technology for ships. This technology would offer a new alternative to noise reduction and increase reliability improvement for presently available advanced propulsion systems. These MHD systems would offer high speed and

J. X. Bouillard; G. F. Berry; E. S. Pierson

1990-01-01

67

Oxygen-enriched air for MHD power plants  

NASA Technical Reports Server (NTRS)

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.

Ebeling, R. W., Jr.; Cutting, J. C.; Burkhart, J. A.

1979-01-01

68

Magnetohydrodynamic (MHD) analyses of various forms of activity and their propagation through helio spheric space  

NASA Technical Reports Server (NTRS)

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.

Wu, S. T.

1987-01-01

69

Evaluation of a candidate material for a coal-fired magnetohydrodynamic (MHD) high temperature recuperative air heater  

NASA Astrophysics Data System (ADS)

In order to achieve the desired efficiency in the magnetohydrodynamic (MHD) cycle, one of two procedures must be employed. The first is to inject pure oxygen during combustion in order to achieve higher combustion temperatures which will yield better conversion efficiencies. The other is to preheat the combustor air through the use of high temperature air heaters (HTAH). A recuperative air heater heats the combustor air directly by passing it through tubes which are in the exhaust gas flow before sending it into the combustor. The procedure of passing air through the furnace requires a material for the tubes which will withstand the high temperatures and corrosive environment of the furnace and should have a high heat transfer coefficient. All of the necessary properties seem to exist in ceramic materials, so ceramics have begun to be studied for high temperature air heaters as well as other high temperature applications. One such effort to evaluate the performance of a ceramic composite tube in a coal fired MHD facility in order to determine any changes in the tube material after exposure to high temperature and a highly corrosive environment is outlined. A recuperative high temperature air heater (HTAH) would be positioned in the radiant furnace, because the radiant furnace provides conditions comparable to an actual MHD facility and is adequate for testing HTAH materials. The temperature conditions in the furnace range from approximately 1600 C to 1890 C, and velocities of approximately 12 m/s to 100 m/s were measured depending on the location in the furnace. The evaluated tube was placed in the furnace in a reducing environment with approximately 14 m/s velocity, 1650 C gas temperature, and 1230 C tube temperature.

Winkler, J.; Dahotre, N. B.; Boss, W.

70

Evaluation of the ECAS open cycle MHD power plant design  

NASA Technical Reports Server (NTRS)

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.

Seikel, G. R.; Staiger, P. J.; Pian, C. C. P.

1978-01-01

71

Performance analysis of seawater magnetohydrodynamics (MHD) thruster propulsion systems within a test loop  

SciTech Connect

The recent dramatic development in high temperatures superconducting materials and the successful operation of large and sophisticated magnet systems make it desirable to further develop the MHD seawater propulsion technology for ships. This technology would offer a new alternative to noise reduction and increase reliability improvement for presently available advanced propulsion systems. These MHD systems would offer high speed and silent operation. A candidate test loop in which seawater is self-propulsed by MHD thrust is investigated and studied using a first order and three-dimensional analyses. Increase of skin friction coefficients due to Hartmann effects are investigated. A preliminary analysis of end effects indicates that these effects may be significant at low load factors. 11 refs., 9 figs.

Bouillard, J.X.; Berry, G.F. (Argonne National Lab., IL (USA)); Pierson, E.S. (Purdue Univ., Indianapolis, IN (USA))

1990-01-01

72

Oxygen-enriched air for MHD power plants  

Microsoft Academic Search

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.

R. W. Ebeling Jr.; J. A. Burkhart

1979-01-01

73

Multi-MW Closed Cycle MHD Nuclear Space Power Via Nonequilibrium He/Xe Working Plasma  

NASA Technical Reports Server (NTRS)

Prospects for a low specific mass multi-megawatt nuclear space power plant were examined assuming closed cycle coupling of a high-temperature fission reactor with magnetohydrodynamic (MHD) energy conversion and utilization of a nonequilibrium helium/xenon frozen inert plasma (FIP). Critical evaluation of performance attributes and specific mass characteristics was based on a comprehensive systems analysis assuming a reactor operating temperature of 1800 K for a range of subsystem mass properties. Total plant efficiency was expected to be 55.2% including plasma pre-ionization power, and the effects of compressor stage number, regenerator efficiency and radiation cooler temperature on plant efficiency were assessed. Optimal specific mass characteristics were found to be dependent on overall power plant scale with 3 kg/kWe being potentially achievable at a net electrical power output of 1-MWe. This figure drops to less than 2 kg/kWe when power output exceeds 3 MWe. Key technical issues include identification of effective methods for non-equilibrium pre-ionization and achievement of frozen inert plasma conditions within the MHD generator channel. A three-phase research and development strategy is proposed encompassing Phase-I Proof of Principle Experiments, a Phase-II Subscale Power Generation Experiment, and a Phase-III Closed-Loop Prototypical Laboratory Demonstration Test.

Litchford, Ron J.; Harada, Nobuhiro

2011-01-01

74

Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger  

DOEpatents

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.

Berry, G.F.; Minkov, V.; Petrick, M.

1981-11-02

75

Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger  

DOEpatents

A magnetohydrodynamic (MHD) power generating system 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.

Berry, Gregory F. (Naperville, IL); Minkov, Vladimir (Skokie, IL); Petrick, Michael (Joliet, IL)

1988-01-01

76

Experiments in Magnetohydrodynamics  

ERIC Educational Resources Information Center

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)

Rayner, J. P.

1970-01-01

77

Experimental determination of the MHD-EMP effects on power distribution transformers  

SciTech Connect

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.

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

78

Design study of superconducting magnets for a combustion magnetohydrodynamic (MHD) generator  

NASA Technical Reports Server (NTRS)

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.

Thome, R. J.; Ayers, J. W.

1977-01-01

79

MHD Integrated Topping Cycle Project  

NASA Astrophysics Data System (ADS)

The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Projects represents the culmination of the proof-of-concept (POC) development stage in the U.S. Department of Energy (DOE) program to advance MHD technology to the early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt slagging coal combustion subsystem. Avco is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits). Westinghouse is responsible for the current consolidation subsystem.

1992-01-01

80

Data-driven Three-Dimensional (3D) Global Magnetohydrodynamic (MHD) Model with Radiation to Study the Solar Atmospheric Dynamics  

NASA Astrophysics Data System (ADS)

In this presentation, we describe a self-consistent, three-dimensional, global compressible, and resistive magnetohydrodynamic (MHD) model together with time-dependent boundary conditions based on the projected method of characteristics at the source surface (photosphere) to accommodate the observations. The additional physics included in this model are differential rotation, meridional flow, effective diffusion, and cyclonic turbulence effects in which the complex magnetic field structure can be generated through the nonlinear interactions between the plasma flows and magnetic field. To illustrate the capability of this model, we selected GONG's global transverse velocity measurements of synoptic chart CR2009 near the photosphere and SOLIS full-resolution LOS magnetic field maps of synoptic chart CR2009 on the photosphere as the inputs to drive the model to simulate the equilibrium state and compute the energy transport across the photosphere. To show the advantage of using both measured magnetic field and transverse velocity data, we have investigated two cases: (1) with the inputs of the LOS magnetic field and transverse velocity measurements, and (2) with the input of only the LOS magnetic field. For these two cases, the simulation results presented here are a three-dimensional coronal magnetic field configuration, density distribution on the photosphere and 1.5 solar radii, and the solar wind in the corona. The deduced physical characteristics are the total current helicity and the synthetic emission.

Wu, Shi

2012-02-01

81

MHD mixed convection flow of a power law nanofluid over a vertical stretching sheet with radiation effect  

NASA Astrophysics Data System (ADS)

A similarity solution of the steady magnetohydrodynamic (MHD) mixed convection boundary layer flow due to a stretching vertical heated sheet in a power law nanofluid with thermal radiation effect is theoretically studied. The governing system of partial differential equations is first transformed into a system of ordinary differential equations. The transformed equations are solved numerically using the shooting method. The influence of pertinent parameters such as the nanoparticle volume fraction parameter, the magnetic parameter, the buoyancy or mixed convection parameter and the radiation parameter on the flow and heat transfer characteristics is discussed. Comparisons with published results are also presented.

Aini Mat, Nor Azian; Arifin, Norihan Md.; Nazar, Roslinda; Ismail, Fudziah; Bachok, Norfifah

2013-09-01

82

Commercial realization of MHD - A challenge for superconducting magnets  

Microsoft Academic Search

The magnetohydrodynamic (MHD) approach to electric power generation offers a unique combination of high-efficiency large-scale power generation and the capability of meeting air quality standards even when high-sulfur coal is used as fuel. The paper reviews the status of the development of fossil-fuel-fired open-cycle MHD generators and highlights the particular importance of the superconducting magnet. Parameters of existing MHD superconducting

V. A. Ovcharenko

1978-01-01

83

H2-O2 combustion powered steam-MHD central power systems  

NASA Technical Reports Server (NTRS)

Estimates are made for both the performance and the power costs of H2-O2 combustion powered steam-MHD central power systems. 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.

Seikel, G. R.; Smith, J. M.; Nichols, L. D.

1974-01-01

84

MAGNETOHYDRODYNAMIC WAVES AND CORONAL HEATING: UNIFYING EMPIRICAL AND MHD TURBULENCE MODELS  

SciTech Connect

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.

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

85

Design study of superconducting magnets for a combustion magnetohydrodynamic /MHD/ generator  

NASA Technical Reports Server (NTRS)

Results are presented for a trade-off and preliminary design study on concepts of a superconducting magnet system for a combustion MHD generator test facility. The main objective is to gain insight into the magnitude of the project in terms of physical characteristics and cost. The net result of a first-phase evaluation of attractive design alternatives is to concentrate subsequent efforts on (1) a racetrack coil geometry with an operating temperature of 4.2 K, (2) a racetrack coil geometry with an operating temperature of 2.0 K, and (3) a rectangular saddle coil geometry with an operating temperature of 4.2 K. All three systems are to produce 8 T, and use NbTi superconductor and iron for field enhancement. Design characteristics of the three systems are described. It is shown that the racetrack and rectangular saddle coil geometries seem most suitable for this application, the former because of its simplicity and the latter because of its efficient use of material. Advantages of the rectangular saddle over the two other systems are stressed.

Thome, R. J.; Ayers, J. W.; Hrycaj, T. M.; Burkhart, J. A.

1978-01-01

86

Use of a Nonequilibrium MHD Generator for Conversion of SNTP Nuclear Thermal Rocket Exhaust to DC Electric Power for a Multimegawatt Nuclear Electric Propulsion System  

NASA Astrophysics Data System (ADS)

This paper explores a method by which the energy of a high speed flowing gas can efficiently be converted into DC electric power by a magnetohydrodynamic (MHD) generator. A nonequilibrium state may be created in the working fluid during the ionization process using an arc discharge. This nonequilibrium state may possibly be sustained in the fluid using the waste heat byproduct of the natural operation of the generator, if certain characteristics of the fluid/MHD system are maintained. The improved efficiency of the resulting nonequilibrium MHD generator not only allows the system to deliver increased power to the load, but reduces the amount of energy to be expelled from the closed fluid cycle by a radiator.

Finley, Charles J.

1994-07-01

87

MHD Advanced Power Train Phase I, Final Report, Volume 6  

SciTech Connect

Under contract to the Department of Energy, Westinghouse has prepared the definition of a program plan for the development of an MHD Advanced Power Train (APT). The scope of work of this contract includes conceptual designs of early commercial MHD/steam electric plants (topping/bottoming) ranging from 200 to 1000 Mw(e). These plant designs were prepared during 1982 and made use of a system analysis model that provides performance and design information and economic estimates. In early April 1984, DOE requested westinghouse to perform special studies under the existing APT contract to aid the Department in evaluating MHD program options. Two tasks were defined by DOE: the first task was to evaluate an 80 MW(t) integrated test system (with steam electric bottoming cycle) for installation at the CDIF in Butte, Montana; the second task was to investigate placing a 50 MW(e) MHD topping stage onto an existing steam electric plant (as a retrofit). This volume of the final report documents the results of these special studies. Highlights of the studies were presented orally to DOE on May 15, 1984.

A. R. Jones

1985-08-01

88

MHD Advanced Power Train Phase I, Final Report, Volume 7  

SciTech Connect

This appendix provides additional data in support of the MHD/Steam Power Plant Analyses reported in report Volume 5. The data is in the form of 3PA/SUMARY computer code printouts. The order of presentation in all four cases is as follows: (1) Overall Performance; (2) Component/Subsystem Information; (3) Plant Cost Accounts Summary; and (4) Plant Costing Details and Cost of Electricity.

A. R. Jones

1985-08-01

89

Electron magnetohydrodynamics  

Microsoft Academic Search

Electron magnetohydrodynamics is a new branch of theoretical plasma physics with many applications to problems of pulsed plasmas and controlled magnetic fusion, astrophysics and physics of solids. EMH is the multicomponent MHD theory reduced, in the limit of short space and time scales and\\/or strong fields and high currents, to a form of electron hydrodynamics on a background of immovable

A. V. Gordeev; A. S. Kingsep; L. I. Rudakov

1994-01-01

90

Plasma plume MHD power generator and method  

DOEpatents

A method is described of generating power at a situs exposed to the solar wind which comprises creating at separate sources at the situs discrete plasma plumes extending in opposed directions, providing electrical communication between the plumes at their source and interposing a desired electrical load in the said electrical communication between the plumes.

Hammer, J.H.

1993-08-10

91

Experiments on H2-O2MHD power generation  

NASA Technical Reports Server (NTRS)

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.

Smith, J. M.

1980-01-01

92

MHD Power Generation Prospects for Commercial and Space Applications  

Microsoft Academic Search

(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

W. Steve Shepard

1987-01-01

93

An electrodeless AC MHD generator and pump  

Microsoft Academic Search

Summary form only given. An electrodeless magnetohydrodynamics (MHD) generator and pump have been developed whose major advantages are that the electrodeless design avoids electrode arcing and damage and that the AC coupling avoids the high-current, low-voltage DC that has caused power transfer difficulties in the past. The basic concept is to provide an iron core linking a closed current path

I. Alexeff; J. Brickey; S. Mitchell

1990-01-01

94

Gyroscopic analog for magnetohydrodynamics  

SciTech Connect

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.

Holm, D.D.

1982-07-20

95

Gyroscopic analog for magnetohydrodynamics  

SciTech Connect

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.

Holm, D.D.

1981-01-01

96

Analytical investigation of critical phenomena in MHD power generators  

SciTech Connect

Critical phenomena in the Arnold Engineering Development Center (AEDC) High Performance Demonstration Experiment (HPDE) and the US U-25 Experiment, are analyzed. Also analyzed are the performance of a NASA-specified 500 MW(th) flow train and computations concerning critica issues for the scale-up of MHD Generators. The HPDE is characterized by computational simulations of both the nominal conditions and the conditions during the experimental runs. The steady-state performance is discussed along with the Hall voltage overshoots during the start-up and shutdown transients. The results of simulations of the HPDE runs with codes from the Q3D and TRANSIENT code families are compared to the experimental results. The results of the simulations are in good agreement with the experimental data. Additional critica phenomena analyzed in the AEDC/HPDE are the optimal load schedules, parametric variations, the parametric dependence of the electrode voltage drops, the boundary layer behavior, near electrode phenomena with finite electrode segmentation, and current distribution in the end regions. The US U-25 experiment is characterized by computational simulations of the nominal operating conditions. The steady-state performance for the nominal design of the US U-25 experiment is analyzed, as is the dependence of performance on the mass flow rate. A NASA-specified 500 MW(th) MHD flow train is characterized for computer simulation and the electrical, transport, and thermodynamic properties at the inlet plane are analyzed. Issues for the scale-up of MHD power trains are discussed. The AEDC/HPDE performance is analyzed to compare these experimental results to scale-up rules.

Not Available

1980-07-31

97

Analysis of the Magneto-Hydrodynamic (MHD) Energy Bypass Engine for High-Speed Air-Breathing Propulsion  

NASA Technical Reports Server (NTRS)

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.

Riggins, David W.

2002-01-01

98

Engineering support for magnetohydrodynamic power plant analysis and design studies  

NASA Technical Reports Server (NTRS)

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.

Carlson, A. W.; Chait, I. L.; Marchmont, G.; Rogali, R.; Shikar, D.

1980-01-01

99

Magnetohydrodynamic power generation. Quarterly report, September 1-December 31, 1984  

SciTech Connect

The research program consists of the following topics: Boundary layers and generator loss mechanisms: (More specifically, this research concerns the nature and effects of MHD-induced secondary flow, i.e., the circulation of gas over the channel cross-plane); Plasma nonuniformities and instabilities: (More specifically, this work is aimed at the measurement of changes in the acoustic velocities by MHD effects. These effects are intimately tied to the questions of possible instabilities in large-scale MHD generators.); Investigation of rod electrodes: (Rod electrodes should produce a more uniform current distribution and thereby may permit operation at higher Hall fields.); Seed-slag interaction and the reactivity of coal: (The question of the magnitude of potassium vapor loss owing to absorption by coal slag is an important factor in the economics of MHD generator operation. Also of importance is the attainment of complete energy release from pulverized coal particles in short times, to minimize heat loss and maximize electrical conductivity.); and Disk generators: (The disk geometry offers several advantages over linear channels, such as the simplicity of the electrode configuration and the magnet system.).

Kruger, C.H.; Eustis, R.H.; Mitchner, M; Self, S.A.

1984-12-01

100

S. Chandrasekhar and magnetohydrodynamics  

Microsoft Academic Search

This chapter summarizes the many fundamental contributions of Chandrasekhar to the subject of hydromagnetics or magnetohydrodynamics (MHD) with particular attention to the generation, static equilibrium, and dynamical stability-instability of magnetic field in various idealized settings with conceptual application to astro- nomical problems. His interest in MHD seems to have arisen first in connection with the turbulence of electrically conducting fluid

E. N. Parker

1996-01-01

101

MHD Energy Bypass Scramjet Engine  

NASA Technical Reports Server (NTRS)

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.

Mehta, Unmeel B.; Bogdanoff, David W.; Park, Chul; Arnold, Jim (Technical Monitor)

2001-01-01

102

Parametric study of potential early commercial MHD power plants  

NASA Technical Reports Server (NTRS)

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.

Hals, F. A.

1979-01-01

103

Coupled generator and combustor performance calculations for potential early commercial MHD power plants  

NASA Technical Reports Server (NTRS)

A parametric study of the performance of the MHD generator and combustor components of potential early commercial open-cycle MHD/steam power plants is presented. Consideration is given to the effects of air heater system concept, MHD combustor type, coal type, thermal input power, oxygen enrichment of the combustion, subsonic and supersonic generator flow and magnetic field strength on coupled generator and combustor performance. The best performance is found to be attained with a 3000 F, indirectly fired air heater, no oxygen enrichment, Illinois no. 6 coal, a two-stage cyclone combustor with 85% slag rejection, a subsonic generator, and a magnetic field configuration yielding a constant transverse electric field of 4 kV/m. Results indicate that optimum net MHD generator power is generally compressor-power-limited rather than electric-stress-limited, with optimum net power a relatively weak function of operating pressure.

Dellinger, T. C.; Hnat, J. G.; Marston, C. H.

1979-01-01

104

Parametric study of potential early commercial power plants Task 3-A MHD cost analysis  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

105

MHD Integrated Topping Cycle Project  

NASA Astrophysics Data System (ADS)

The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to the early commercial development stage for utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW(sub t)) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW(sub t) power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990's, an engineering data base on the reliability, availability, maintainability, and performance of the system will be available to allow scaleup of the prototypical designs to the next development level.

1992-03-01

106

MHD Integrated Topping Cycle Project  

SciTech Connect

The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW{sub t}) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW{sub t} power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990's, an engineering data base on the reliability, availability, maintainability and performance of the system will be available to allow scaleup of the prototypical designs to the next development level. This Sixteenth Quarterly Technical Progress Report covers the period May 1, 1991 to July 31, 1991.

Not Available

1992-03-01

107

A Self-Consistent Numerical Magnetohydrodynamic (MHD) Model of Helmet Streamer and Flux-Rope Interactions: Initiation and Propagation of Coronal Mass Ejections (CMEs)  

NASA Technical Reports Server (NTRS)

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.

Wu, S. T.; Guo, W. P.

1997-01-01

108

A meshfree weak-strong (MWS) form method for the unsteady magnetohydrodynamic (MHD) flow in pipe with arbitrary wall conductivity  

NASA Astrophysics Data System (ADS)

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.

Dehghan, Mehdi; Salehi, Rezvan

2013-12-01

109

ECONOMIC COMPARISON OF MHD EQUILIBRIUM OPTIONS FOR ADVANCED STEADY STATE TOKAMAK POWER PLANTS  

E-print Network

ECONOMIC COMPARISON OF MHD EQUILIBRIUM OPTIONS FOR ADVANCED STEADY STATE TOKAMAK POWER PLANTS D for commercial tokamak power plants. The economic prospects of future designs are compared for several tokamak for future power plants. 1. INTRODUCTION The development path to economical and environ- mentally attractive

Najmabadi, Farrokh

110

MGMHD. Multigrid 3-D Magnetohydrodynamics  

SciTech Connect

MGMHD is a three-dimensional code for the analysis of magnetohydrodynamic (MHD) channels (generators, diffusers, and thrusters) for compressible and incompressible, laminar and turbulent, iso- and noniso-thermal fluids.

Bouillard, J.X.; Berry, G.F.; Krazinski, J.L. [Argonne National Laboratory, IL (United States); Vanka, S.P. [University of Illinois, Urbana, IL (United States)

1992-02-19

111

Double-duct liquid metal magnetohydrodynamic engine  

DOEpatents

An internal combustion, liquid metal (LM) magnetohydrodynamic (MHD) engine and an alternating current (AC) magnetohydrodynamic generator, are used in combination to provide useful AC electric energy output. The engine design has four pistons and a double duct configuration, with each duct containing sodium potassium liquid metal confined between free pistons located at either end of the duct. The liquid metal is forced to flow back and forth in the duct by the movement of the pistons, which are alternatively driven by an internal combustion process. In the MHD generator, the two LM-MHD ducts pass in close proximity through a Hartmann duct with output transformer. AC power is produced by operating the engine with the liquid metal in the two generator ducts always flowing in counter directions. The amount of liquid metal maintained in the ducts may be varied. This provides a variable stroke length for the pistons. The engine/generator provides variable AC power at variable frequencies that correspond to the power demands of the vehicular propulsion. Also the engine should maintain nearly constant efficiency throughout the range of power usage. Automobiles and trucks could be powered by the invention, with no transmission or power converter devices being required.

Haaland, Carsten M. (Oak Ridge, TN)

1997-01-01

112

Double-duct liquid metal magnetohydrodynamic engine  

DOEpatents

An internal combustion, liquid metal (LM) magnetohydrodynamic (MHD) engine and an alternating current (AC) magnetohydrodynamic generator, are used in combination to provide useful AC electric energy output. The engine design has-four pistons and a double duct configuration, with each duct containing sodium potassium liquid metal confined between free pistons located at either end of the duct. The liquid metal is forced to flow back and forth in the duct by the movement of the pistons, which are alternatively driven by an internal combustion process. In the MHD generator, the two LM-MHD ducts pass in close proximity through a Hartmann duct with output transformer. AC power is produced by operating the engine with the liquid metal in the two generator ducts always flowing in counter directions. The amount of liquid metal maintained in the ducts may be varied. This provides a variable stroke length for the pistons. The engine/generator provides variable AC power at variable frequencies that correspond to the power demands of the vehicular propulsion. Also the engine should maintain nearly constant efficiency throughout the range of power usage. Automobiles and trucks could be powered by the invention, with no transmission or power converter devices being required.

Haaland, Carsten M. (Oak Ridge, TN)

1995-01-01

113

Direct Energy Conversion Fission Reactor, Gaseous Core Reactor with Magnetohydrodynamic (MHD) Generator; Final Report - Part I and Part II  

SciTech Connect

This report focuses on the power conversion cycle and efficiency. The technical issues involving the ionization mechanisms, the power management and distribution and radiation shielding and safety will be discussed in future reports.

Samim Anghaie; Blair Smith; Travis Knight

2002-11-12

114

Efficient magnetohydrodynamic simulations on graphics processing units with CUDA  

NASA Astrophysics Data System (ADS)

Magnetohydrodynamic (MHD) simulations based on the ideal MHD equations have become a powerful tool for modeling phenomena in a wide range of applications including laboratory, astrophysical, and space plasmas. In general, high-resolution methods for solving the ideal MHD equations are computationally expensive and Beowulf clusters or even supercomputers are often used to run the codes that implemented these methods. With the advent of the Compute Unified Device Architecture (CUDA), modern graphics processing units (GPUs) provide an alternative approach to parallel computing for scientific simulations. In this paper we present, to the best of the author's knowledge, the first implementation of MHD simulations entirely on GPUs with CUDA, named GPU-MHD, to accelerate the simulation process. GPU-MHD supports both single and double precision computations. A series of numerical tests have been performed to validate the correctness of our code. Accuracy evaluation by comparing single and double precision computation results is also given. Performance measurements of both single and double precision are conducted on both the NVIDIA GeForce GTX 295 (GT200 architecture) and GTX 480 (Fermi architecture) graphics cards. These measurements show that our GPU-based implementation achieves between one and two orders of magnitude of improvement depending on the graphics card used, the problem size, and the precision when comparing to the original serial CPU MHD implementation. In addition, we extend GPU-MHD to support the visualization of the simulation results and thus the whole MHD simulation and visualization process can be performed entirely on GPUs.

Wong, Hon-Cheng; Wong, Un-Hong; Feng, Xueshang; Tang, Zesheng

2011-10-01

115

Exploratory study of several advanced nuclear-MHD power plant systems.  

NASA Technical Reports Server (NTRS)

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.

Williams, J. R.; Clement, J. D.; Rosa, R. J.; Yang, Y. Y.

1973-01-01

116

MAGNETOHYDRODYNAMICS MAGNETOHYDRODYNAMICS (or MHD for short) is  

E-print Network

to another (such as ice to water) by heat- ing, and if you raise the temperature of gas suÃ?ciently it changes #18; T 10 6 K #19; 2 #16; n 10 17 m 3 #17; 1 m; which is typically 3 cm in the solar chromosphere. Particular attention is given to the induction equation and the Lorentz force with which a magnetic #12;eld

Priest, Eric

117

Nuclear-electric magnetohydrodynamic propulsion for submarine. Master's thesis  

SciTech Connect

The thesis analyzes the superconducting technology for a shipboard magnetohydrodynamic propulsion system. Based on the the principles of magnetohydrodynamics (MHD), the concept of open-water efficiency was used to optimize the preliminary design of the MHD thruster. After the baseline submarine hull modeled after the Los Angeles class submarine was selected, propulsive efficiency and the top speed for four variant MHD submarines were evaluated. The design criteria were set at a 100-MWt nuclear reactor power upper limit and a requirement of 30 knots for the top speed. This required advanced reactor plants and advanced energy conversion systems. The selection of High Temperature Gas Reactor (HTGR) and Liquid-Metal Fast Breeder Reactor (LMFBR) was based on the combined merits of safety, environmental impact, high source temperature and maximum-volume power density (KW/L). With the reactor outlet temperatures of 2000 K, direct-cycle energy conversion-systems gave the best results in terms of thermal efficiency and propulsion plant power density. Two energy conversion systems selected were closed-cycle gas turbine geared to a superconducting generator, and closed-cycle liquid-metal MHD generator. Based on submarine reliability and safety, the option of using an intermediate heat exchanger was also considered. Finally, non-nuclear support systems affected by the advanced power plant and MHD propulsion, stressing submarine safety, are proposed.

Bednarczyk, A.A.

1989-05-01

118

Priority pollutant analysis of MHD-derived combustion products  

NASA Astrophysics Data System (ADS)

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

Parks, Katherine D.

119

Analyses Of Underwater Magnetohydrodynamic Propulsion  

Microsoft Academic Search

Sea water magnetohydrodynamic (MHD) propulsion for marine vehicles offers many unique features. There is no need for propellers, and therefore no noise associated that. Gear reduction system for the shafts is thus no longer needed. It offers maneuverbility by directional thrusts along with quietness. The theories of MHD pump jet propulsion are discussed in detail in this paper. A so-called

J. B. Gilbertt; T. F. Lint

1990-01-01

120

Closed Cycle Magnetohydrodynamic Nuclear Space Power Generation Using Helium/Xenon Working Plasma  

NASA Technical Reports Server (NTRS)

A multimegawatt-class nuclear fission powered closed cycle magnetohydrodynamic space power plant using a helium/xenon working gas has been studied, to include a comprehensive system analysis. Total plant efficiency was expected to be 55.2 percent including pre-ionization power. The effects of compressor stage number, regenerator efficiency, and radiation cooler temperature on plant efficiency were investigated. The specific mass of the power generation plant was also examined. System specific mass was estimated to be 3 kg/kWe for a net electrical output power of 1 MWe, 2-3 kg/kWe at 2 MWe, and approx.2 kg/KWe at >3 MWe. Three phases of research and development plan were proposed: (1) Phase I-proof of principle, (2) Phase II-demonstration of power generation, and (3) Phase III-prototypical closed loop test.

Litchford, R. J.; Harada, N.

2005-01-01

121

Evaluation of technical feasibility of closed-cycle non-equilibrium MHD power generation with direct coal firing. Final report, Task 1  

SciTech Connect

Program accomplishments in a continuing effort to demonstrate the feasibility of direct coal fired, closed cycle, magnetohydrodynamic power generation are detailed. These accomplishments relate to all system aspects of a CCMHD power generation system including coal combustion, heat transfer to the MHD working fluid, MHD power generation, heat and cesium seed recovery and overall systems analysis. Direct coal firing of the combined cycle has been under laboratory development in the form of a high slag rejection, regeneratively air cooled cyclone coal combustor concept, originated within this program. A hot bottom ceramic regenerative heat exchanger system was assembled and test fired with coal for the purposes of evaluating the catalytic effect of alumina on NO/sub x/ emission reduction and operability of the refractory dome support system. Design, procurement, fabrication and partial installation of a heat and seed recovery flow apparatus was accomplished and was based on a stream tube model of the full scale system using full scale temperatures, tube sizes, rates of temperature change and tube geometry. Systems analysis capability was substantially upgraded by the incorporation of a revised systems code, with emphasis on ease of operator interaction as well as separability of component subroutines. The updated code was used in the development of a new plant configuration, the Feedwater Cooled (FCB) Brayton Cycle, which is superior to the CCMHD/Steam cycle both in performance and cost. (WHK)

Not Available

1981-11-01

122

Energetic Particles and Magnetohydrodynamic Activity in SSX  

Microsoft Academic Search

Results from the Swarthmore Spheromak Experiment (SSX) indicate that formation and partial merging of two spheromak plasmas can be described well by a magnetohydrodynamic (MHD) picture in which there is substantial evolution towards force free states within each vessel, while reconnection activity, also described reasonably well by MHD, occurs in the region of interaction. MHD simulations (Lukin et al, Phys.

W. H. Matthaeus; G. Qin; V. S. Lukin; M. R. Brown

2001-01-01

123

Measurement of the Electric Fluctuation Spectrum of Magnetohydrodynamic Turbulence S. D. Bale,1  

E-print Network

´n waves [10]. Here we report the first measured power spectrum of electric fluctuations in solar wind Laboratory, University of California, Berkeley, California 94720, USA 2 School of Physics and Astronomy June 2005) Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show the spectral

California at Berkeley, University of

124

Relaxation model for extended magnetohydrodynamics: Comparison to magnetohydrodynamics for dense Z-pinches  

NASA Astrophysics Data System (ADS)

It is shown that the two-fluid model under a generalized Ohm's law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm's law determines the current density to a system where Ohm's law determines the electric field. This result is used to derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.

Seyler, C. E.; Martin, M. R.

2011-01-01

125

Relaxation model for extended magnetohydrodynamics: Comparison to magnetohydrodynamics for dense Z-pinches  

SciTech Connect

It is shown that the two-fluid model under a generalized Ohm's law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm's law determines the current density to a system where Ohm's law determines the electric field. This result is used to derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.

Seyler, C. E. [School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853 (United States); Martin, M. R. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

2011-01-15

126

Lecture 2 Basic MHD Equations MHD = Magnetohydrodynamics  

E-print Network

T jB lawsOHM' BvEj vvvv Ã?+= A generalization of Ohm's law 3-fluid model term normal to and , it is called Hall currentB v E v #12;Induction Equation Ohm's Law: BBv t B BBBBBv tyconductivielectric plasmawithmovingreferenceofframein the - ohm m E v #12;If ignore electron inertia & pressure

127

Gradient Particle Magnetohydrodynamics  

E-print Network

We introduce Gradient Particle Magnetohydrodynamics (GPM), a new Lagrangian method for magnetohydrodynamics based on gradients corrected for the locally disordered particle distribution. The development of a numerical code for MHD simulation using the GPM algorithm is outlined. Validation tests simulating linear and nonlinear sound waves, linear MHD waves, advection of magnetic fields in a magnetized vortex, hydrodynamical shocks, and three-dimensional collapse are presented, demonstrating the viability of an MHD code using GPM. The characteristics of a GPM code are discussed and possible avenues for further development and refinement are mentioned. We conclude with a view of how GPM may complement other methods currently in development for the next generation of computational astrophysics.

Jason L. Maron; Gregory G. Howes

2001-07-24

128

Turbulent Magnetohydrodynamic Jet Collimation and Thermal Driving  

E-print Network

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.

Peter T. Williams

2003-12-21

129

Estimates of Optimal Operating Conditions for Hydrogen-Oxygen Cesium-Seeded Magnetohydrodynamic Power Generator  

NASA Technical Reports Server (NTRS)

The value of percent seed, oxygen to fuel ratio, combustion pressure, Mach number, and magnetic field strength which maximize either the electrical conductivity or power density at the entrance of an MHD power generator was obtained. The working fluid is the combustion product of H2 and O2 seeded with CsOH. The ideal theoretical segmented Faraday generator along with an empirical form found from correlating the data of many experimenters working with generators of different sizes, electrode configurations, and working fluids, are investigated. The conductivity and power densities optimize at a seed fraction of 3.5 mole percent and an oxygen to hydrogen weight ratio of 7.5. The optimum values of combustion pressure and Mach number depend on the operating magnetic field strength.

Smith, J. M.; Nichols, L. D.

1977-01-01

130

Performance calculations for 200-1000 MWe MHD/steam power plants  

NASA Technical Reports Server (NTRS)

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.

Staiger, P. J.

1981-01-01

131

Optimization of the oxidant supply system for combined cycle MHD power plants  

NASA Technical Reports Server (NTRS)

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.

Juhasz, A. J.

1982-01-01

132

Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Hypersonic Airbreathing Engines  

NASA Technical Reports Server (NTRS)

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.

Litchford, R. J.; Cole, J. W.; Bityurin, V. A.; Lineberry, J. T.

2000-01-01

133

Results from conceptual design study of potential early commercial MHD/steam power plants  

NASA Technical Reports Server (NTRS)

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.

Hals, F.; Kessler, R.; Swallom, D.; Westra, L.; Zar, J.; Morgan, W.; Bozzuto, C.

1981-01-01

134

Interaction between MHD generator and DC-AC power conversion system  

Microsoft Academic Search

Transient characteristics of an MHD power generating system including a DC-AC inverter are analyzed using a time-dependent quasi-one-dimensional approximation. The generator model considered is Faraday type of U-25 class with heavy-oil and air combustion gas. It is found that a short-circuited fault of the invertor may become more serious than an open-circuited fault, resulting in significant gas velocity reduction. An

D. Tanaka

1982-01-01

135

Analytical investigation of critical MHD (magnetohydrodynamics) phenomena: Quarterly technical progress report for the period 1 May 1983-31 July 1983. [Secondary flows  

SciTech Connect

Data and post-test observations from the AEDC High Performance Demonstration Experiment Run MI-007-016 exhibit clear evidence of precisely the magnetoaerothermal effect predicted by STD Research Corporation in 1981. Unaveraged 40 millisecond data from this run were displayed and analyzed. A detailed three-dimensional simulation was performed under conditions of a period late in the test in which the anomalous behavior attributed to the magnetoaerothermal effect had apparently ''healed.'' Generally good agreement is found between the simulation and the data late in the run, but the anomalous data early in the test depart substantially from the trends of this initial simulation. A one dimensional reference design has been defined for a 1000 MW(th) MHD generator under conditions of interest in the Advanced Power Train (APT) Program. Quasi-three-dimensional calculations of the behavior of the reference design in the presence of nonideal conditions such as slag current leakage and cold walls were performed. An examination of the possibilities of measuring magnetoaerothermal effects in other facilities than the AEDC/HPDE was made for the operating conditions of the Avco Mark VI Reference Channel No. 3. Preliminary quasi-one-dimensional simulations carried out to assist in the definition of conditions showed that the conditions obtained to date in the Avco facility with enhanced conductivity are marginally sufficient to promote the magnetoaerothermal effects. Suggestions for enhancing these effects are made.

Not Available

1983-08-01

136

Investigation of nonuniform magnetic field effects on MHD channel performance  

NASA Astrophysics Data System (ADS)

The effects of a nonuniform magnetic field on magnetohydrodynamic (MHD) generator performance are examined. A coupled fluid and electrodynamic computational procedure is developed to study the nonuniform magnetic field in a MHD channel flow analysis. The parabolized Navier-Stokes and Maxwell equations used in the procedure are presented. The method is applied to a Faraday generator and a HPDE channel. The experimental data reveal an improvement in power output for the shaped-field case, and this correlates well with the theoretical data.

Liu, B. L.; Schmidt, H. J.; Wu, Y. C. L.

1986-05-01

137

Scale-locality of magnetohydrodynamic turbulence  

SciTech Connect

We investigate the scale-locality of cascades of conserved invariants at high kinetic and magnetic Reynolds numbers in the 'inertial-inductive range' of magnetohydrodynamic (MHD) turbulence, where velocity and magnetic field increments exhibit suitable power-law scaling. We prove that fluxes of total energy and cross-helicity - or, equivalently, fluxes of Elsaesser energies - are dominated by the contributions of local triads. Corresponding spectral transfers are also scale-local when defined using octave wavenumber bands. Flux and transfer of magnetic helicity may be dominated by nonlocal triads. The magnetic stretching term also may be dominated by non-local triads but we prove that it can convert energy only between velocity and magnetic modes at comparable scales. We explain the disagreement with numerical studies that have claimed conversion non locally between disparate scales. We present supporting data from a 1024{sup 3} simulation of forced MHD turbulence.

Aluie, Hussein [Los Alamos National Laboratory; Eyink, Gregory L [JOHNS HOPKINS UNIV.

2009-01-01

138

The infinite interface limit of multiple-region relaxed magnetohydrodynamics  

SciTech Connect

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.

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

139

MHD Performance Demonstration Experiment, October 1, 1981-September 30, 1982  

SciTech Connect

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 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, 1981, to September 30, 1982. During this period, approximately 28 MW of electrical power was produced during a short duration test. A magnet failure and subsequent damage in a fairly inaccessible location required a significant amount of time to repair, seriously limiting the number of power production tests. The repair and some improvements were accomplished and the magnet successfully tested to the 4.0 Tesla (T) level. Combustor operation was refined and improved and the entire flow train is once again ready for high magnetic field tests.

Whitehead, G.L.; Christensen, L.S.; Felderman, E.J.; Lowry, R.L.; Bordenet, E.J.; Allee, E.G.

1983-01-01

140

Advanced fusion MHD power conversion using the CFAR (compact fusion advanced Rankine) cycle concept  

SciTech Connect

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 costs of electricity than previous concepts. This paper describes the unique features of the CFAR cycle and a high- temperature blanket designed to take advantage of it as well as the predicted performance of the MHD disk generators using mercury seeded with cesium. 40 refs., 8 figs., 3 tabs.

Hoffman, M.A.; Campbell, R.; Logan, B.G. (California Univ., Davis, CA (USA); Lawrence Livermore National Lab., CA (USA))

1988-10-01

141

Methods of reducing energy consumption of the oxidant supply system for MHD/steam power plants  

NASA Technical Reports Server (NTRS)

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.

Juhasz, A. J.

1983-01-01

142

Corotating interaction regions during the recent solar minimum: The power and limitations of global MHD modeling  

NASA Astrophysics Data System (ADS)

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.

Riley, Pete; Linker, Jon A.; Lionello, R.; Mikic, Z.

2012-07-01

143

Three-Dimensional Numerical Modeling of Magnetohydrodynamic Augmented Propulsion Experiment  

NASA Technical Reports Server (NTRS)

Over the past several years, NASA Marshall Space Flight Center has engaged in the design and development of an experimental research facility to investigate the use of diagonalized crossed-field magnetohydrodynamic (MHD) accelerators as a possible thrust augmentation device for thermal propulsion systems. In support of this effort, a three-dimensional numerical MHD model has been developed for the purpose of analyzing and optimizing accelerator performance and to aid in understanding critical underlying physical processes and nonideal effects. This Technical Memorandum fully summarizes model development efforts and presents the results of pretest performance optimization analyses. These results indicate that the MHD accelerator should utilize a 45deg diagonalization angle with the applied current evenly distributed over the first five inlet electrode pairs. When powered at 100 A, this configuration is expected to yield a 50% global efficiency with an 80% increase in axial velocity and a 50% increase in centerline total pressure.

Turner, M. W.; Hawk, C. W.; Litchford, R. J.

2009-01-01

144

Multi-region relaxed magnetohydrodynamics with flow  

NASA Astrophysics Data System (ADS)

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.

Dennis, G. R.; Hudson, S. R.; Dewar, R. L.; Hole, M. J.

2014-04-01

145

Multi-region relaxed magnetohydrodynamics with flow  

SciTech Connect

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.

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

146

Analytical investigation of critical MHD (magnetohydrodynamics) phenomena: Quarterly technical progress report for the period 1 August 1983-31 October 1983. [Secondary flows  

SciTech Connect

Recent effort has focused on analysis of AEDC/HPDE Run MI007-016. Beyond the fact that it achieved one of the highest interaction and performance levels of any fossil-fueled MHD experiment to date, HPDE Run MI007-016 is important because it clearly exhibited phenomena which will play a crucial and even limiting role in scaling MHD generators to commercial performance levels. These phenomena fall into the general class of magnetoaerothermal effects previously described by STD Research Corporation. In order to understand the exact balance of mechanisms which caused the magnetoaerothermal instability in Run MI-007-016 and which later caused it to ''heal'' STD Research Corporation has carried out quasi-three-dimensional and three-dimensional simulations of the precise conditions of three time periods at the beginning, middle and end of the run. At high levels of MHD interaction, magnetoaerothermal effects promote nonuniformity in the electrical and thermal stresses on the walls. Therefore, in planning duration tests under ''commercial conditions'', the local conditions on the perimeter must be matched, rather than ''average'' or ''core'' conditions. The role of magnetoaerothermal effects in determining ultimate performance at the very high MHD interaction levels indicated by simplified system analyses remains to be investigated experimentally. 7 refs., 11 figs.

Not Available

1983-11-01

147

Potential vorticity in magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

A version of Noether's second theorem using Lagrange multipliers is used to investigate fluid relabelling symmetries conservation laws in magnetohydrodynamics (MHD). We obtain a new generalized potential vorticity type conservation equation for MHD which takes into account entropy gradients and the J × B force on the plasma due to the current J and magnetic induction B. This new conservation law for MHD is derived by using Noether's second theorem in conjunction with a class of fluid relabelling symmetries in which the symmetry generator for the Lagrange label transformations is non-parallel to the magnetic field induction in Lagrange label space. This is associated with an Abelian Lie pseudo algebra and a foliated phase space in Lagrange label space. It contains as a special case Ertel's theorem in ideal fluid mechanics. An independent derivation shows that the new conservation law is also valid for more general physical situations.

Webb, G. M.; Mace, R. L.; Mace

2015-01-01

148

Potential Vorticity in Magnetohydrodynamics  

E-print Network

A version of Noether's second theorem using Lagrange multipliers is used to investigate fluid relabelling symmetries conservation laws in magnetohydrodynamics (MHD). We obtain a new generalized potential vorticity type conservation equation for MHD which takes into account entropy gradients and the ${\\bf J}\\times{\\bf B}$ force on the plasma due to the current ${\\bf J}$ and magnetic induction ${\\bf B}$. This new conservation law for MHD is derived by using Noether's second theorem in conjunction with a class of fluid relabelling symmetries in which the symmetry generator for the Lagrange label transformations is non-parallel to the magnetic field induction in Lagrange label space. This is associated with an Abelian Lie pseudo algebra and a foliated phase space in Lagrange label space. It contains as a special case Ertel's theorem in ideal fluid mechanics. An independent derivation shows that the new conservation law is also valid for more general physical situations.

G. M. Webb; R. L. Mace

2014-07-16

149

Parabolized Navier-Stokes Code for Computing Magneto-Hydrodynamic Flowfields  

NASA Technical Reports Server (NTRS)

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'.

Mehta, Unmeel B. (Technical Monitor); Tannehill, J. C.

2003-01-01

150

BOOK REVIEW: Nonlinear Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Nonlinear magnetohydrodynamics by Dieter Biskamp is a thorough introduction to the physics of the most impressive non-linear phenomena that occur in conducting magnetoplasmas. The basic systems, in which non-trivial dynamic processes are observed, accompanied by changes of geometry of the magnetic field and the effects of energy transformation (magnetic energy into kinetic energy or the opposite effect in magnetic dynamos), are the plasma magnetic confinement systems for nuclear fusion and space plasmas, mainly the solar plasma. A significant number of the examples of the dynamic processes considered are taken from laboratory plasmas, for which an experimental check of the theory is possible. Therefore, though the book is intended for researchers and students interested in both laboratory, including nuclear fusion, and astrophysical plasmas, it is most probably closer to the first category of reader. In the Introduction the author notes that unlike the hydrodynamics of non-conducting fluids, where the phenomena caused by rapid fluid motions are the most interesting, for plasmas in a strong magnetic field the quasi-static configurations inside which the local dynamic processes occur are often the most important. Therefore, the reader will also find in this book rather traditional material on the theory of plasma equilibrium and stability in magnetic fields. In addition, it is notable that, as opposed to a linear theory, the non-linear theory, as a rule, cannot give quite definite explanations or predictions of phenomena, and consequently there are in the book many results obtained by consideration of numerical models with the use of supercomputers. The treatment of non-linear dynamics is preceded by Chapters 2 to 4, in which the basics of MHD theory are presented with an emphasis on the role of integral invariants of the magnetic helicity type, a derivation of the reduced MHD equations is given, together with examples of the exact solutions of the equilibrium equations of a plasma in a magnetic field (which will be used further in models of dynamic processes), approaches to the description of three dimensional (3-D) equilibrium are briefly discussed, and the basis of the theory of linear instabilities and the basic types of MHD instabilities, with account taken of ideal resistive modes, are considered. The value of the material of these chapters is that here in a brief form the results of numerous researches in this area are presented, and frequently with a fresh point of view of old results. Chapters 5 to 10 are devoted to the subject of the book, non-linear magnetohydrodynamics. In the introduction to Chapter 5 the author pays attention to the fact that long standing doubts about the feasibility of magnetic thermonuclear reactors because of inevitable instabilities of non-uniform plasmas have been overcome in the last two decades: the plasma in tokamaks is rather well confined, despite the presence of some instabilities. The latter, as a rule, result only in the redistribution of current and plasma pressure profiles and some increase of transport, but can also lead to extremely undesirable effects. In this connection in Chapter 5 the attention of the reader is directed to the physics of the most important plasma instabilities in tokamaks. Models of the development of external and internal kink modes in tokamaks are considered, including the `vacuum bubble' model in shearless plasmas, the evolution of the resistive tearing mode together with saturation of the magnetic islands arising at a tearing instability. The rather long Chapter 6 is devoted to the fundamentals of the magnetic hydrodynamic dissipative process in the magnetic field line reconnection. This process of rapid dissipation of the energy of a magnetic field, having in the simplest case different directions in two adjacent volumes of plasma, underlies the theory of the phenomenon of powerful flares in the solar chromosphere, resulting in the well-known `magnetic storms' on the earth, and the theory of rather dangerous disruptive instabilities in tokamaks. Aft

Shafranov, V.

1998-08-01

151

Temporal Intermittency of Energy Dissipation in Magnetohydrodynamic Turbulence  

NASA Astrophysics Data System (ADS)

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.

Zhdankin, Vladimir; Uzdensky, Dmitri A.; Boldyrev, Stanislav

2015-02-01

152

Temporal Intermittency of Energy Dissipation in Magnetohydrodynamic Turbulence  

E-print Network

Energy dissipation in magnetohydrodynamic (MHD) turbulence is known to be highly intermittent in space, being concentrated in sheet-like 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/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 signatu...

Zhdankin, Vladimir; Boldyrev, Stanislav

2015-01-01

153

Temporal intermittency of energy dissipation in magnetohydrodynamic turbulence.  

PubMed

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

Zhdankin, Vladimir; Uzdensky, Dmitri A; Boldyrev, Stanislav

2015-02-13

154

Criteria For MHD Sea Mater Propulsion  

Microsoft Academic Search

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

J. T. Lineberry; Y. C. L. Susan Wu

1990-01-01

155

MHD control in burning plasmas MHD control in burning plasmas  

NASA Astrophysics Data System (ADS)

Fusion physics focuses on the complex behaviour of hot plasmas confined by magnetic fields with the ultimate aim to develop a fusion power plant. In the future generation of tokamaks like ITER, the power generated by the fusion reactions substantially exceeds the external input power (Pfusion}/Pin >= 10). When this occurs one speaks of a burning plasma. Twenty per cent of the generated fusion power in a burning plasma is carried by the charged alpha particles, which transfer their energy to the ambient plasma in collisions, a process called thermalization. A new phenomenon in burning plasmas is that the alpha particles, which form a minority but carry a large fraction of the plasma kinetic energy, can collectively drive certain types of magneto-hydrodynamic (MHD) modes, while they can suppress other MHD modes. Both types of MHD modes can have desirable effects on the plasma, as well as be detrimental to the plasma. For example, the so-called sawtooth instability, on the one hand, is largely responsible for the transport of the thermalized alpha particles out of the core, but, on the other hand, may result in the loss of the energetic alphas before they have fully thermalized. A further undesirable effect of the sawtooth instability is that it may trigger other MHD modes such as neoclassical tearing modes (NTMs). These NTMs, in turn, are detrimental to the plasma confinement and in some cases may even lead to disruptive termination of the plasma. At the edge of the plasma, finally, so-called edge localized modes or ELMs occur, which result in extremely high transient heat and particle loads on the plasma-facing components of a reactor. In order to balance the desired and detrimental effects of these modes, active feedback control is required. An additional complication occurs in a burning plasma as the external heating power, which is nowadays generally used for plasma control, is small compared to the heating power of the alpha particles. The scientific challenge in the field of burn control is to find the proper balance between desired and detrimental effects of the various MHD modes and to develop the methods and tools for active feedback control of MHD modes in burning plasmas. Therefore, it is necessary to understand the dynamics of the system, in this case the mutual interactions between the fast alpha particles and the MHD instabilities. Since burning plasmas do not yet exist, the relevant experimental work until ITER comes into full operation needs to be largely based on alpha-particle simulation experiments in which the alpha particles are accelerated to high energies by means of special heating techniques. The precise conditions of a burning plasma can be only partly mimicked in present tokamaks. Hence, also a detailed computational modelling effort is needed, in order to understand the impact of findings in present machines for those of the future. In 2011 two dedicated workshops were devoted to MHD control. Firstly, there was a workshop on Control of Burning Plasmas that took place from 21-25 March 2011 at the Lorentz Centre in Leiden, The Netherlands. Secondly, the 480th Wilhelm and Else Heraeus Seminar that took place from 16-18 June in Bad Honnef, Germany was devoted to Active Control of Instabilities in Hot Plasmas. This special issue presents a collection of papers that have been presented at the two workshops, along with a few papers that are the result of an open call to contribute to this special issue.

Donné, Tony; Liang, Yunfeng

2012-07-01

156

Improvement of Scramjet Performance-Experimental Demonstration of MHD Acceleration  

NASA Technical Reports Server (NTRS)

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.

Bogdanoff, David W.; Park, Chul; Mehta, Unmeel B.; Arnold, James (Technical Monitor)

2001-01-01

157

MHD performance demonstration experiment, October 1, 1080September 30, 1981  

Microsoft Academic Search

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

G. L. Whitehead; L. S. Christenson; E. J. Felderman; R. L. Lowry; E. J. Bordenet

1981-01-01

158

MHD Performance Demonstration Experiment, October 1, 1981September 30, 1982  

Microsoft Academic Search

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 sufficiently large scale to verify that projected commercial MHD objectives are possible. This report describes the

G. L. Whitehead; L. S. Christensen; E. J. Felderman; R. L. Lowry; E. J. Bordenet; E. G. Allee

1983-01-01

159

Interaction between MHD generator and dc-ac power conversion system  

NASA Astrophysics Data System (ADS)

Transient characteristics of an MHD power generating system including a DC-AC inverter are analyzed using a time-dependent quasi-one-dimensional approximation. The generator model considered is Faraday type of U-25 class with heavy-oil and air combustion gas. It is found that a short-circuited fault of the invertor may become more serious than an open-circuited fault, resulting in significant gas velocity reduction. An open-circuited fault, if retained for more than 5-8 ms, can substantially increase the gas velocity at the upstream end of the fault region. A protection system composed of a fast-acting DC circuit-breaker and an emergency load resistance is proposed. The switching speed of the DC breaker must be about 500 microsec to stop a pressure increase, resulting, for example, from the short-circuiting of 20 electrode pairs, before it reaches 120% of the initial level.

Tanaka, D.

1983-10-01

160

Summary and evaluation of the conceptual design study of a potential early commercial MHD power plant (CSPEC)  

NASA Astrophysics Data System (ADS)

The conceptual design study of a potential early commercial MHD power plant (CSPEC) is described and the results are summarized. Each of two contractors did a conceptual design of an approximtely 1000 MWe open-cycle MHD/steam plant with oxygen enriched combustion air preheated to an intermediate temperatue in a metallic heat exchanger. The contractors were close in their overall plant efficiency estimates but differed in their capital cost and cost of electricity estimates, primarily because of differences in balance-of-plant material, contingency, and operating and maintenance cost estimates. One contractor concluded that its MHD plant design compared favorably in cost of electricity with conventional coal-fired steam plants. The other contractor is making such a comparison as part of a follow-on study. Each contractor did a preliminary investigation of part-load performance and plant availability. The results of NASA studies investigating the effect of plant size and oxidizer preheat temperature on the performance of CSPEC-type MHD plants are also described. The efficiency of a 1000 MWe plant is about three points higher than of a 200 MWe plant. Preheating to 1600 F gives an efficiency about one and one-half points higher than preheating to 800 F for all plant sizes. For each plant size and preheat temperature there is an oxidizer enrichment level and MHD generator length that gives the highest plant efficiency.

Staiger, P. J.; Penko, P. F.

1982-01-01

161

Multi-region relaxed magnetohydrodynamics with anisotropy and flow  

SciTech Connect

We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes pressure anisotropy and general plasma flows. This anisotropic extension to our previous isotropic model is motivated by Sun and Finn's model of relaxed anisotropic magnetohydrodynamic equilibria. We prove that as the number of plasma regions becomes infinite, our anisotropic extension of MRxMHD reduces to anisotropic ideal MHD with flow. The continuously nested flux surface limit of our MRxMHD model is the first variational principle for anisotropic plasma equilibria with general flow fields.

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, Canberra, Australian Capital Territory 0200 (Australia); Hudson, S. R. [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States)

2014-07-15

162

Multi-region relaxed magnetohydrodynamics with anisotropy and flow  

NASA Astrophysics Data System (ADS)

We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes pressure anisotropy and general plasma flows. This anisotropic extension to our previous isotropic model is motivated by Sun and Finn's model of relaxed anisotropic magnetohydrodynamic equilibria. We prove that as the number of plasma regions becomes infinite, our anisotropic extension of MRxMHD reduces to anisotropic ideal MHD with flow. The continuously nested flux surface limit of our MRxMHD model is the first variational principle for anisotropic plasma equilibria with general flow fields.

Dennis, G. R.; Hudson, S. R.; Dewar, R. L.; Hole, M. J.

2014-07-01

163

Channel-wall limitations in the magnetohydrodynamic induction generator  

NASA Technical Reports Server (NTRS)

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.

Jackson, W. D.; Pierson, E. S.

1969-01-01

164

Simulation of three-dimensional multi-phase flow characteristics in the deswirl section of the CDIF MHD power train  

SciTech Connect

A three-dimensional, two-phase, turbulent flow computer code was used to predict flow characteristics of seed particles and coal gas in the deswirl section of the CDIF MHD power train system. Seed material which has a great effect on the overall performance of the MHD system is injected in the deswirl against the swirling coal gas flow coming from the first stage combustor. While testing the MHD system, excessive seed material (70% more than theoretical value) was required to achieve design operating conditions. Calculations show that the swirling coal gas flow turns a 90 degree angle to minimize the swirl motion before entering a second stage combustor and many seed particles are too slow to react to the flow turning and deposit on the walls of the deswirl section. Some seed material deposited on the walls is covered by slag layer and removed from the gas flow. The reduction of seed material in the gas flow decreases MHD power generation significantly. A computational experiment was conducted and its results show that seed injection on the wall can be minimized by simply changing the seed injection and an optimum location was identified. If seed is injected from the location of choice, the seed deposition is reduced by a factor of 10 compared to the original case.

Chang, S.L.; Lottes, S.A.; Petrick, M.

1994-06-01

165

Evaluation of technical feasibility of closed-cycle non-equilibrium MHD power generation with direct coal firing. Final report, Task I  

SciTech Connect

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)

Not Available

1981-11-01

166

Analytical investigation of critical MHD (magnetohydrodynamics) phenomena: Quarterly technical progress report for the period 1 November 1983-31 January 1984. [AERL Mark VI secondary flows  

SciTech Connect

To understand the differences between the Avco experiments and the AEDC/HPDE tests, one must consider all of the listed characteristic scaling parameters in addition to the interaction parameters. Work is presently underway to isolate the dominant parameters which determine whether the anode current concentration will occur. Two likely candidates are (1) channel height to electrode pitch ratio and (5) total current in channel. The former may introduce finite segmentation effects which modify the Hall current distribution, and hence the secondary flow pattern in the boundary layers. The total current available to couple into a current concentration may determine whether a boundary layer temperature disturbance ''runs away'' or is stable. These initial experiments have been extremely fruitful and should be continued with better diagnostics (more instrumented electrodes, downstream pressure traverses, etc.). The Mark VI affords the opportunity to validate the multidimensional models at appropriate levels of interaction and to separate the scale-dependent design parameters and from those that depend solely upon the MHD interaction. Nevertheless, it will be necessary to validate the conclusions reached at the Mark VI scale at the scale of the AEDC/HPDE before commercial units can be designed with confidence. 5 refs., 11 figs.

Not Available

1984-02-01

167

Isogeometric analysis in reduced magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Isogeometric analysis (IGA) consists of using computer-aided design (CAD) models defining the geometry of the computational domain using both B-splines and non-uniform rational B-splines (NURBS) to represent the unknowns that are the solution of a partial differential equation using a finite element principle. In this paper, we review the main ideas of IGA and apply it to a reduced magnetohydrodynamic (MHD) model that is used in tokamak simulations. This is a first step towards arbitrary high-order and smooth approximations of reduced MHD generalizing the Bézier splines approach of Czarny and Huysmans (2008 J. Comput. Phys. 227 7423-45).

Ratnani, A.; Sonnendrücker, E.

2012-01-01

168

Method for manufacturing magnetohydrodynamic electrodes  

DOEpatents

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.

Killpatrick, D.H.; Thresh, H.R.

1980-06-24

169

A numerical study of the alpha model for two-dimensional magnetohydrodynamic turbulent flows  

E-print Network

A numerical study of the alpha model for two-dimensional magnetohydrodynamic turbulent flows Pablo turbulence and compare the results of numerical solutions of the primitive MHD equations with their alpha-model the "Lagrangian-averaged" model, for two-dimensional incompressible magnetohydrodynamic (MHD) turbulence

Pouquet, Annick

170

An AC magnetohydrodynamic micropump: towards a true integrated microfluidic system  

SciTech Connect

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.

Lee, A P; Lemoff, A V; McConaghy, C F; Miles, R R

1999-03-01

171

Parametric study of potential early commercial MHD power plants. Task 3: Parameter variation of plant size  

NASA Technical Reports Server (NTRS)

Plants with a nominal output of 200 and 500 MWe and conforming to the same design configuration as the Task II plant were investigated. This information is intended to permit an assessment of the competitiveness of first generation MHD/steam plants with conventional steam plants over the range of 200 to 1000 MWe. The results show that net plant efficiency of the MHD plant is significantly higher than a conventional steam plant of corresponding size. The cost of electricity is also less for the MHD plant over the entire plant size range. As expected, the cost differential is higher for the larger plant and decreases with plant size. Even at the 200 MWe capacity, however, the differential in COE between the MHD plant and the conventional plant is sufficient attractive to warrant serious consideration. Escalating fuel costs will enhance the competitive position of MHD plants because they can utilize the fuel more efficiently than conventional steam plants.

Hals, F. A.

1981-01-01

172

Parametric study of potential early commercial MHD power plants. Task 3: Parameter variation of plant size  

NASA Astrophysics Data System (ADS)

Plants with a nominal output of 200 and 500 MWe and conforming to the same design configuration as the Task II plant were investigated. This information is intended to permit an assessment of the competitiveness of first generation MHD/steam plants with conventional steam plants over the range of 200 to 1000 MWe. The results show that net plant efficiency of the MHD plant is significantly higher than a conventional steam plant of corresponding size. The cost of electricity is also less for the MHD plant over the entire plant size range. As expected, the cost differential is higher for the larger plant and decreases with plant size. Even at the 200 MWe capacity, however, the differential in COE between the MHD plant and the conventional plant is sufficient attractive to warrant serious consideration. Escalating fuel costs will enhance the competitive position of MHD plants because they can utilize the fuel more efficiently than conventional steam plants.

Hals, F. A.

1981-09-01

173

Magnetohydrodynamic ship propulsion with superconducting magnets  

Microsoft Academic Search

The feasibility of magnetohydrodynamic (MHD) ship propulsion using superconducting magnets is reviewed in light of recent advances in high-temperature superconductivity. The scaling relations for the electrical and hydraulic efficiencies of MHD pump-jets show that overall efficiencies >50% are feasible at speeds of 40 knots and higher provided that magnetic fields >5T can be maintained over volumes of the order of

D. L. Mitchell; D. U. Gubser

1988-01-01

174

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device  

DOEpatents

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output. 5 figs.

Haaland, C.M.; Deeds, W.E.

1999-07-13

175

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device  

DOEpatents

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output.

Haaland, Carsten M. (Dadeville, AL); Deeds, W. Edward (Knoxville, TN)

1999-01-01

176

Numerical simulation study of disk MHD generator for nonequilibrium plasma (NPG) system  

SciTech Connect

Design and performance prediction of a disk-shaped magnetohydrodynamic (MHD) generator, which is applied to the nonequilibrium plasma generator (NPG) system, have been carried out by means of a quasi-one-dimensional numerical simulation. The calculations have been performed for generator with constant height which is planned to be used for NPG-MHD disk generator pulse power demonstration. A maximum enthalpy extraction ratio obtained from the present calculation reached up to 20%, and, in this case, the electron temperature of working plasma fluctuated in the unstable regime against ionization instability. Taking into account this phenomenon, in order to obtain much higher generator performance, the MHD channel, in which electron temperature was kept at 5000 K, was designed. With this channel, enthalpy extraction ratio of 40% and output power of 7.2 MW were achieved without major modification of the supersonic nozzle, the inlet swirl vanes and the configuration of magnet system.

Tsunoda, Kazumi [Shibaura Institute of Technology, Tokyo (Japan); Harada, Nob [Nagaoka Univ. of Technology (Japan)

1995-12-31

177

Magnetohydrodynamics propulsion: a global approach of an inner DC thruster  

Microsoft Academic Search

Magnetohydrodynamics (MHD) applied to sea water is able to provide a noiseless ship propulsion. As the principle is known since the sixties, many works have been performed in the nineties aiming at better efficiencies due to superconducting electromagnets use. A one-dimensional global calculation is made in order to determine the best geometry of a MHD propeller, the different parts of

Patrick Boissonneau

1999-01-01

178

Propulsive efficiencies of magnetohydrodynamic submerged vehicular propulsors. Final report  

Microsoft Academic Search

Magnetohydrodynamic (MHD) ship propulsion is the process of propelling a vehicular structure by a seawater electromagnetic pump. This propulsion system can be applied to a surface ship or a submerged vehicle; however, in this work only submerged vehicles at depths where wave effects can be neglected were considered. Although a number of different arrangements for a MHD propulsion system are

S. H. Brown; J. S. Walker; N. A. Sondergaard; P. J. Reilly; D. E. Bagley

1990-01-01

179

Energetic particles and magnetohydrodynamic activity in the Swarthmore Spheromak Experiment  

Microsoft Academic Search

Results from the Swarthmore Spheromak Experiment (SSX) [M. R. Brown, Phys. Plasmas 6, 1717 (1999)] indicate that formation and partial merging of two spheromak plasmas can be described well by a magnetohydrodynamic (MHD) picture in which there is substantial evolution towards force free states within each vessel, while reconnection activity, also described reasonably well by MHD, occurs in the region

G. Qin; V. S. Lukin; C. D. Cothran; M. R. Brown; W. H. Matthaeus

2001-01-01

180

Using Faraday Rotation to Probe Magnetohydrodynamic Instabilities in Intracluster Media  

Microsoft Academic Search

It has recently been suggested that conduction-driven magnetohydrodynamic (MHD) instabilities may operate at all radii within an intracluster medium (ICM) and profoundly affect the structure of a cluster's magnetic field. Where MHD instabilities dominate the dynamics of an ICM, they will re-orient magnetic field lines perpendicular to the temperature gradient inside a cooling core or parallel to the temperature gradient

Tamara Bogdanovic; Christopher S. Reynolds; Richard Massey

2011-01-01

181

Multi-symplectic magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

A multi-symplectic formulation of ideal magnetohydrodynamics (MHD) is developed based on the Clebsch variable variational principle in which the Lagrangian consists of the kinetic minus the potential energy of the MHD fluid modified by constraints using Lagrange multipliers that ensure mass conservation, entropy advection with the flow, the Lin constraint, and Faraday's equation (i.e. the magnetic flux is Lie dragged with the flow). The analysis is also carried out using the magnetic vector potential à where ?=Ã. d x is Lie dragged with the flow, and B=?×Ã. The multi-symplectic conservation laws give rise to the Eulerian momentum and energy conservation laws. The symplecticity or structural conservation laws for the multi-symplectic system corresponds to the conservation of phase space. It corresponds to taking derivatives of the momentum and energy conservation laws and combining them to produce n(n-1)/2 extra conservation laws, where n is the number of independent variables. Noether's theorem for the multi-symplectic MHD system is derived, including the case of non-Cartesian space coordinates, where the metric plays a role in the equations.

Webb, G. M.; McKenzie, J. F.; Zank, G. P.; Zank

2014-10-01

182

Magnetohydrodynamic Turbulence and the Geodynamo  

NASA Technical Reports Server (NTRS)

The ARES Directorate at JSC has researched the physical processes that create planetary magnetic fields through dynamo action since 2007. The "dynamo problem" has existed since 1600, when William Gilbert, physician to Queen Elizabeth I, recognized that the Earth was a giant magnet. In 1919, Joseph Larmor proposed that solar (and by implication, planetary) magnetism was due to magnetohydrodynamics (MHD), but full acceptance did not occur until Glatzmaier and Roberts solved the MHD equations numerically and simulated a geomagnetic reversal in 1995. JSC research produced a unique theoretical model in 2012 that provided a novel explanation of these physical observations and computational results as an essential manifestation of broken ergodicity in MHD turbulence. Research is ongoing, and future work is aimed at understanding quantitative details of magnetic dipole alignment in the Earth as well as in Mercury, Jupiter and its moon Ganymede, Saturn, Uranus, Neptune, and the Sun and other stars.

Shebalin, John V.

2014-01-01

183

MHD Integrated Topping Cycle Project. Sixteenth quarterly technical progress report, May 1991--July 1991  

SciTech Connect

The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW{sub t}) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW{sub t} power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990`s, an engineering data base on the reliability, availability, maintainability and performance of the system will be available to allow scaleup of the prototypical designs to the next development level. This Sixteenth Quarterly Technical Progress Report covers the period May 1, 1991 to July 31, 1991.

Not Available

1992-03-01

184

A simulation of the IPS variations from a magnetohydrodynamical simulation  

NASA Technical Reports Server (NTRS)

Calculations of the variations of interplanetary scintillation (IPS) from a disturbance simulated by a 3-D magnetohydrodynamical (MHD) model of the solar wind are presented. The simulated maps are compared with observations and it is found that the MHD model reproduces the qualitative features of observed disturbances. The disturbance produced by the MHD simulation is found to correspond in strength with the weakest disturbance which can be reliably detected by existing single station IPS observations.

Tappin, S. J.; Dryer, M.; Han, S. M.; Wu, S. T.

1987-01-01

185

Open-cycle magnetohydrodynamic power plant with CO.sub.2 recycling  

DOEpatents

A method of converting the chemical energy of fossil fuel to electrical and mechanical energy with a MHD generator. The fossil fuel is mixed with preheated oxygen and carbon dioxide and a conducting seed of potassium carbonate to form a combustive and electrically conductive mixture which is burned in a combustion chamber. The burned combustion mixture is passed through a MHD generator to generate electrical energy. The burned combustion mixture is passed through a diffuser to restore the mixture approximately to atmospheric pressure, leaving a spent combustion mixture which is used to heat oxygen from an air separation plant and recycled carbon dioxide for combustion in a high temperature oxygen preheater and for heating water/steam for producing superheated steam. Relatively pure carbon dioxide is separated from the spent combustion mixture for further purification or for exhaust, while the remainder of the carbon dioxide is recycled from the spent combustion mixture to a carbon dioxide purification plant for removal of water and any nitrous oxides present, leaving a greater than 98% pure carbon dioxide. A portion of the greater then 98% pure carbon dioxide stream is recovered and the remainder is recycled to combine with the oxygen for preheating and combination with the fossil fuel to form a combustion mixture.

Berry, Gregory F. (Naperville, IL)

1991-01-01

186

Alfven wave tomography for cold magnetohydrodynamic plasmas I. Y. Dodin and N. J. Fisch  

E-print Network

of ideal magnetohydrodynamics MHD nonlinear equations. The evolution of the MHD spectrum is shown inhomogeneities, as they scatter off of them. The application of the MHD spectrum evolution equation Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 Received 31 August 2001

187

Survey of MHD plant applications  

NASA Technical Reports Server (NTRS)

Open-cycle MHD is one of the major R&D efforts in the Department of Energy's program to meet the national goal of reducing U.S. dependence on oil through increased utilization of coal. MHD offers an effective way to use coal to produce electric power at low cost in a highly efficient and environmentally acceptable manner. Open-cycle MHD plants are categorized by the MHD combustor oxidizer, its temperature and the method of preheat. The paper discusses MHD baseline plant design, open-cycle MHD plant in the Energy Conversion Alternatives Study (ECAS), early commercial MHD plants, conceptual studies of the engineering test facility, retrofit (addition of an MHD topping cycle to an existing steam plant), and other potential applications and concepts. Emphasis is placed on a survey of both completed and ongoing studies to define both commercial and pilot plant design, cost, and performance.

Lynch, J. J.; Seikel, G. R.; Cutting, J. C.

1979-01-01

188

An HLLC Riemann Solver for Magnetohydrodynamics  

E-print Network

: approximate Riemann solver, HLL, HLLE, HLLC, magneto-hydrodynamics (MHD) 1 Introduction Many astrophysics. A typical example of the single state HLL solver is HLLE scheme by Einfeldt et al. [10], who proposed and positivity conditions. The single-state HLL and HLLE solvers, however, are too diffusive and cannot resolve

Kurien, Susan

189

Numerical Simulations of Strong Incompressible Magnetohydrodynamic Turbulence  

NASA Astrophysics Data System (ADS)

Magnetized turbulence pervades the universe and is likely to play an important role in a variety of astrophysical processes. Magnetohydrodynamics provides the simplest theoretical framework in which phenomenological models for the turbulent dynamics can be built. Numerical simulations are widely used to guide and test the theoretical predictions; however, simulating MHD turbulence is not without its difficulties. Computational power limits the simulations to parameter regimes that are much less extreme than those in astrophysics and often simplifying assumptions are made in order that a wider range of scales can be accessed. After describing the competing theoretical predictions and the numerical approaches that are often employed in studying strong incompressible MHD turbulence, I will present the findings of a series of high-resolution direct numerical simulations. I will discuss the effects that physically motivated simplifying assumptions can have on the numerical solution and its physical interpretation.[4pt] Collaborators: Stanislav Boldyrev (U. Wisconsin - Madison), Fausto Cattaneo (U. Chicago), Jean C. Perez (U. New Hampshire).

Mason, Joanne

2011-11-01

190

Fundamentals of numerical magnetohydrodynamics  

SciTech Connect

Magnetohydrodynamics is a fluid model for the motion of an ionized gas in a magnetic field. In its ideal, non-dissipative form, the Lundquist equations, it has the same mathematical character as the model for gas dynamics. It gives, in the same way, a self-consistent description of the fluid dynamics, including the exchange of momentum and energy between the field and the fluid. However, because of the greater complexity of the physics which they describe, some aspects of the solutions are quite different. The magnetic field introduces a strong anisotropic character to the medium which causes wave propagation to depend on the direction of propagation with respect of the magnetic field. In addition, there are several distinct speeds so that, in general, the responses to disturbances are quite complex. To capture the principal features of the solutions in numerical calculations, several problems must be addressed. Some of these problems are unique to MHD: for example, preserving the solenoidality of the magnetic field. Others are similar to ordinary gas dynamics, such as energy conservation, numerical stability, and computational diffusion, but are more complex or have different consequences for MHD than for ordinary fluid flow. These fundamental problems in the numerical solution of the MHD equations are discussed as four topics: the dispersion of the Lundquist equations and the dispersion and stability of finite difference approximations; the conservation laws of MHD and the achievement of conservation in the numerical solutions; a discussion of convective transport and its role in computational diffusion; and finally, a method for preserving the solenoidality of the magnetic field.

Brackbill, J.U.

1987-01-01

191

Diagnostic development and support of MHD test facilities. Technical progress report, January--March 1991  

SciTech Connect

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.

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

1991-12-31

192

Diagnostic development and support of MHD Test Facilities. Technical progress report, October 1991--December 1991  

SciTech Connect

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

193

Magnetohydrodynamics in Hydra  

NASA Astrophysics Data System (ADS)

The Magnetohydrodynamics package in the ALE radiation-hydrodynamics ICF design code Hydra is based upon a three-dimensional vector finite element method. This defines a set of spaces and differential operators that maintain the zero divergence of the magnetic field exactly. It is fully implicit in time and second order accurate in space. We discuss several improvements to the MHD package. The first addition is an anisotropic tensor based heat conduction method. The second improvement is a method for solving the magnetic diffusion equation for all of the element types resulting from point and line singularities including tetrahedral and pyramid elements. Finally a new magnetic flux advection method was implemented based on the method by A.C Robinson, et al.ootnotetextA.C. Robinson, J. H. J. Niederhaus, V. G. Weirs, E. Love, Int. J. Numer. Meth. Fluids, 65, 1438 (2011)

Koning, J. M.; Kerbel, G. D.; Marinak, M. M.

2011-11-01

194

Results from a large-scale MHD propulsion experiment  

Microsoft Academic Search

Magnetohydrodynamic (MHD) thrusters have long been recognized as potentially attractive candidates for ship propulsion because such systems eliminate the conventional rotating drive components. The MHD thruster is essentially an electromagnetic (EM) pump operating in seawater. An electrical current is passed directly through the seawater and interacts with an applied magnetic field; the interaction of the magnetic field and the electrode

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

1992-01-01

195

Seawater Conductivity Enhancement By Acid Injection For The Mhd Thrusters  

Microsoft Academic Search

This paper analyzes the enhancement of seawater conductivity by seeding. A direct application of this technology is the improvement of vehicle speed and efficiency of marine vessels utilizing the magnetohydrodynamic (MHD) internal duct, direct current thruster propulsion system. Seeding can be achieved by injecting a strong acid (or base) upstream of the MHD thruster channel. Several seeding compounds are compared

T. F. Lint; J. B. Gilbert; J. A. Naggar; T. M. Imblum

1991-01-01

196

Fundamental studies of helical-type seawater MHD generation system  

Microsoft Academic Search

A new MHD (magnetohydrodynamics) generator based on electromotive force using seawater, that is, a helical-type seawater MHD generator with a 7 T solenoid superconducting magnet, is designed, constructed and tested. The constructed generator contains a helical insulation wall made of polyvinyl chloride 140 mm long and 100 mm in diameter, an anode rod made of SUS316 1350 mm long and

Minoru Takeda; Yasuaki Okuji; Teruhiko Akazawa; Xiaojun Liu; Tsukasa Kiyoshi

2005-01-01

197

Electrical characteristics of a seawater MHD thruster. Final report  

Microsoft Academic Search

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

Tempelmeyer

1990-01-01

198

Investigation of nonuniform magnetic field effects on MHD channel performance  

Microsoft Academic Search

The effects of a nonuniform magnetic field on magnetohydrodynamic (MHD) generator performance are examined. A coupled fluid and electrodynamic computational procedure is developed to study the nonuniform magnetic field in a MHD channel flow analysis. The parabolized Navier-Stokes and Maxwell equations used in the procedure are presented. The method is applied to a Faraday generator and a HPDE channel. The

B. L. Liu; H. J. Schmidt; Y. C. L. Wu

1986-01-01

199

Free boundary skin current MHD (magnetohydrodynamic) equilibria  

SciTech Connect

Function theoretic methods in the complex plane are used to develop simple parametric hodograph formulae which generate sharp boundary equilibria of arbitrary shape. The related method of Gorenflo and Merkel is discussed. A numerical technique for the construction of solutions, based on one of the methods is presented. A study is made of the bifurcations of an equilibrium of general form. 28 refs., 9 figs.

Reusch, M.F.

1988-02-01

200

A Nonlinear 3D MHD Code NFTC for Numerical Simulations of Plasma Instabilities in Tokamaks  

Microsoft Academic Search

In this report a new nonlinear 3D MHD code NFTC is presented for the numerical simulations of magnetohydrodynamic (MHD) stability of plasmas. The nonlinear 3D evolution of a tokamak plasma is described by the full (nonreduced, compressible) MHD system of equations in general toroidal geometry. The equations include a viscosity, resistivity and sources. Arbitrary plasma rotation is included in terms

Y. Q. Liu; A. M. Popov; N. N. Popova; A. V. Pedorenko

1997-01-01

201

Magneto-hydrodynamics simulation study of deflagration mode in co-axial plasma accelerators  

SciTech Connect

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.

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

202

Research and development studies for MHD/coal power flow train components. Technical progress report, 1 September 1979-31 August 1980  

SciTech Connect

The aim of this program is to contribute to certain facets of the development of the MHD/coal power system, and particularly the CDIF of DOE with regard to its flow train. Consideration is given specifically to the electrical power take-off, the diagnostic and instrumentation systems, the combustor and MHD channel technology, and electrode alternatives. Within the constraints of the program, high priorities were assigned to the problems of power take-off and the related characteristics of the MHD channel, and to the establishment of a non-intrusive, laser-based diagnostic system. The next priority was given to the combustor modeling and to a significantly improved analysis of particle combustion. Separate abstracts were prepared for nine of the ten papers included. One paper was previously included in the data base. (WHK)

Bloom, M. H.

1980-01-01

203

Magnetohydrodynamic Augmented Propulsion Experiment  

NASA Technical Reports Server (NTRS)

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

Litchford, Ron J.

2008-01-01

204

Summary and evaluation of the parametric study of potential early commercial MHD power plants (PSPEC)  

NASA Technical Reports Server (NTRS)

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.

Staigner, P. J.; Abbott, J. M.

1980-01-01

205

Magnetohydrodynamic Augmented Propulsion Experiment: I. Performance Analysis and Design  

NASA Technical Reports Server (NTRS)

The performance of conventional thermal propulsion systems is fundamentally constrained by the specific energy limitations associated with chemical fuels and the thermal limits of available materials. Electromagnetic thrust augmentation represents one intriguing possibility for improving the fuel composition of thermal propulsion systems, thereby increasing overall specific energy characteristics; however, realization of such a system requires an extremely high-energy-density electrical power source as well as an efficient plasma acceleration device. This Technical Publication describes the development of an experimental research facility for investigating the use of cross-field magnetohydrodynamic (MHD) accelerators as a possible thrust augmentation device for thermal propulsion systems. In this experiment,a 1.5-MW(sub e) Aerotherm arc heater is used to drive a 2-MW(sub e) MHD accelerator. The heatsink MHD accelerator is configured as an externally diagonalized, segmented channel, which is inserted into a large-bore, 2-T electromagnet. The performance analysis and engineering design of the flow path are described as well as the parameter measurements and flow diagnostics planned for the initial series of test runs.

Litchford, R. J.; Cole, J. W.; Lineberry, J. T.; Chapman, J. N.; Schmidt, H. J.; Lineberry, C. W.

2003-01-01

206

Extended Magnetohydrodynamic Simulations of the Helicity Injected Torus (HIT-SI) Spheromak Experiment with the NIMROD Code  

NASA Astrophysics Data System (ADS)

A comparative study of 3-D pressureless resistive (single-fluid) magnetohydrodynamic (rMHD) and 3-D pressureless two-fluid magnetohydrodynamic (2fl-MHD) models of the Helicity Injected Torus experiment (HIT-SI) is presented. HIT-SI is a spheromak current-drive experiment that uses two geometrically asymmetric helicity injectors to generate and sustain toroidal plasmas. The goal of the experiment is to demonstrate that steady inductive helicity injection (SIHI) is a viable method for driving and sustaining a magnetized plasma for the eventual purpose of electricity production with magnetic fusion power. The experiment has achieved sustainment of nearly 100 kA of plasma current for ˜1~ms. Fusion power plants are expected to sustain a burning plasma for many minutes to hours with more than 10~MA of plasma current. The purpose of project is to determine the validity of the single-fluid and two-fluid MHD models of HIT-SI. The comparable size of the collisionless ion skin depth to the diameter of the injectors and resistive skin depth predicates the importance of two-fluid effects. The simulations are run with NIMROD (non-ideal magnetohydrodynamics code with rotation-open discussion), an initial-value, 3-D extended MHD code. A constant and uniform plasma density and temperature are assumed. The helicity injectors are modeled as oscillating normal magnetic and parallel electric field boundary conditions. The simulations use parameters that closely match those of the experiment. The simulation output is compared to the formation time, plasma current, and internal and surface magnetic fields. Results of the study indicate 2fl-MHD shows quantitative agreement with the experiment while rMHD only captures the qualitative features. The validity of each model is assessed based on how accurately it reproduces the global quantities as well as the temporal and spatial dependence of the measured magnetic fields. 2fl-MHD produces the current amplification and formation time demonstrated by HIT-SI with similar internal magnetic fields. rMHD underestimates the current amplification and exhibits a much longer formation time. Biorthogonal decomposition (BD), a powerful mathematical tool for reducing large data sets, is employed to quantify how well the simulations reproduce the measured surface magnetic fields without resorting to a probe-by-probe comparison. BD shows that 2fl-MHD captures the dominant surface magnetic structures and the temporal behavior of these features better than rMHD. In addition to the comparisons with the experiment, a detailed investigation of the rMHD and 2fl-MHD models is undertaken. lambda (mu0 J.B/B2 and current density J are used to track the prominent structures. Both lambda and J show highly dynamic, periodic patterns with significant toroidal non-uniformities, consistent with the magnetic energy spectrum. A spheromak-like object forms only in the toroidally-averaged sense. This structure never fully detaches itself from the regions directly-driven by injectors. Parameter scans are carried out to determine the dependence of current amplification on the plasma resistivity, viscosity, injector oscillation frequency, and the ratio of injector current to injector flux. An energetics analysis based on the evolution of the MHD and Hall dynamos is presented for both models. Results of this analysis indicates a large surge of energy into the spheromak mean-field (the n=0 component) by both dynamos, followed by a steady energy transfer to the n=0 predominantly by the MHD dynamo.

Akcay, Cihan

207

Alfven Wave Tomography for Cold MHD Plasmas  

SciTech Connect

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.

I.Y. Dodin; N.J. Fisch

2001-09-07

208

Energy transfer and locality in magnetohydrodynamic turbulence  

E-print Network

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.

Mahendra K. Verma; Arvind Ayyer; Amar V. Chandra

2005-10-19

209

Energy transfers and locality in magnetohydrodynamic turbulence  

SciTech Connect

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 probably 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.

Verma, Mahendra K.; Ayyer, Arvind; Chandra, Amar V. [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)

2005-08-15

210

Micromachined magnetohydrodynamic actuators and sensors  

DOEpatents

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.

Lee, Abraham P. (Walnut Creek, CA); Lemoff, Asuncion V. (Union City, CA)

2000-01-01

211

Nonlinear Magnetohydrodynamics  

Microsoft Academic Search

Nonlinear magnetohydrodynamics by Dieter Biskamp is a thorough introduction to the physics of the most impressive non-linear phenomena that occur in conducting magnetoplasmas.The basic systems, in which non-trivial dynamic processes are observed, accompanied by changes of geometry of the magnetic field and the effects of energy transformation (magnetic energy into kinetic energy or the opposite effect in magnetic dynamos), are

V. Shafranov

1998-01-01

212

Parametric study of prospective early commercial MHD power plants (PSPEC). General Electric Company, task 1: Parametric analysis  

NASA Technical Reports Server (NTRS)

The performance and cost of moderate technology coal-fired open cycle MHD/steam power plant designs which can be expected to require a shorter development time and have a lower development cost than previously considered mature OCMHD/steam plants were determined. Three base cases were considered: an indirectly-fired high temperature air heater (HTAH) subsystem delivering air at 2700 F, fired by a state of the art atmospheric pressure gasifier, and the HTAH subsystem was deleted and oxygen enrichment was used to obtain requisite MHD combustion temperature. Coal pile to bus bar efficiencies in ease case 1 ranged from 41.4% to 42.9%, and cost of electricity (COE) was highest of the three base cases. For base case 2 the efficiency range was 42.0% to 45.6%, and COE was lowest. For base case 3 the efficiency range was 42.9% to 44.4%, and COE was intermediate. The best parametric cases in bases cases 2 and 3 are recommended for conceptual design. Eventual choice between these approaches is dependent on further evaluation of the tradeoffs among HTAH development risk, O2 plant integration, and further refinements of comparative costs.

Marston, C. H.; Alyea, F. N.; Bender, D. J.; Davis, L. K.; Dellinger, T. C.; Hnat, J. G.; Komito, E. H.; Peterson, C. A.; Rogers, D. A.; Roman, A. J.

1980-01-01

213

MHD performance demonstration experiment, October 1, 1080-September 30, 1981  

SciTech Connect

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.

Whitehead, G. L.; Christenson, L. S.; Felderman, E. J.; Lowry, R. L.; Bordenet, E. J.

1981-12-01

214

Key contributions in MHD power generation. Quarterly technical progress report, September 1, 1979-November 30, 1979  

SciTech Connect

Separate entries were made in the data base for the four tasks which include: (1) investigation of electrical behavior in the vicinity of electrode and insulating walls; (2) studies of critical performance issues in the development of combustion disk generators; (3) development and testing of electrode modules, including studies of insulator properties; and (4) determination of coal combustion kinetics and ash behavior relevant to two-stage MHD combustors, and investigation of the mixing and flow aerodynamics of a high swirl geometry second stage. (WHK)

Louis, J F

1980-03-01

215

Specific Mass Estimates for A Vapor Core Reactor With MHD  

SciTech Connect

This study investigated the development of a system concept for space power generation and nuclear electric propulsion based on a vapor core reactor (VCR) with magnetohydrodynamic (MHD) power conversion system, coupled to a magnetoplasma-dynamic (MPD) thruster. The VCR is a liquid-vapor core reactor concept operating with metallic uranium or uranium tetrafluoride (UF{sub 4}) vapor as the fissioning fuel and alkali metals or their fluorides as working fluid in a closed Rankine cycle with MHD energy conversion. Gaseous and liquid-vapor core reactors can potentially provide the highest reactor and cycle temperature among all existing or proposed fission reactor designs. This unique feature makes this reactor concept a very natural and attractive candidate for very high power (10 to 1000 MWe) and low specific mass (0.4 to 5 kg/kWe) nuclear electric propulsion (NEP) applications since the MHD output could be coupled with minimal power conditioning to MPD thrusters or other types of thruster for producing thrust at very high specific impulse (I{sub sp} 1500 to 10,000 s). The exceptional specific mass performance of an optimized VCRMHD- NEP system could lead to a dramatic reduction in the cost and duration of manned or robotic interplanetary as well as interstellar missions. The VCR-MHD-NEP system could enable very efficient Mars cargo transfers or short (<8 month) Mars round trips with less initial mass in low Earth orbit (IMLEO). The system could also enable highly efficient lunar cargo transfer and rapid missions to other destinations throughout the solar system. (authors)

Knight, Travis; Smith, Blair; Anghaie, Samim [Innovative Nuclear Space Power and Propulsion Institute (INSPI), PO Box 116502, University of Florida, Gainesville, FL 32611-6502 (United States)

2002-07-01

216

Direct Interaction Approximation of Magnetohydrodynamic Turbulence  

E-print Network

In this paper we apply Kraichnan's direct interaction approximation, which is a one loop perturbation expansion, to magnetohydrodynamic turbulence. By substituting the energy spectra both from kolmogorov-like MHD turbulence phenomenology and a generalization of Dobrowolny et al.'s model we obtain Kolmogorov's and Kraichnan's constant for MHD turbulence. We find that the constants depend of the Alfv\\'en ratio and normalized cross helicity; the dependence has been studied here. We also demonstrate the inverse cascade of magnetic energy for Kolmogorov-like models. Our results are in general agreement with the earlier simulation results except for large normalized cross helicity.

Mahendra K. Verma; Jayant K. Bhattacharjee

1995-09-05

217

U-25 MHD generator project. Report for the period May--July 1976  

Microsoft Academic Search

The ERDA-FE MHD Division has the lead role in the U.S. national MHD (magnetohydrodynamic) development effort, in which capacity it has taken the initiative in establishing a number of programs aimed at furthering MHD technology. Within the framework of the formal agreement negotiated in 1973 by the joint U.S.--U.S.S.R. Commission on Scientific and Technical Cooperation, a cooperative effort in MHD

K. D. Kuczen; H. Herman; D. Killpatrick; D. Marchant; D. Swallom; T. Zinnerman

1976-01-01

218

Modeling extreme (Carrington-type) space weather events using three-dimensional MHD code simulations  

NASA Astrophysics Data System (ADS)

There is growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure and systems. In the last two decades, significant progress has been made towards the modeling of space weather events. Three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, and have played a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for existing global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events that have a ground footprint comparable (or larger) to the Carrington superstorm. Results are presented for an initial simulation run with ``very extreme'' constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated ground induced geoelectric field to such extreme driving conditions. We also discuss the results and what they might mean for the accuracy of the simulations. The model is further tested using input data for an observed space weather event to verify the MHD model consistence and to draw guidance for future work. This extreme space weather MHD model is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in earth conductors such as power transmission grids.

Ngwira, C. M.; Pulkkinen, A. A.; Kuznetsova, M. M.; Glocer, A.

2013-12-01

219

MHD and Kinetic Modeling of the Ionospheres of Venus and Mars  

SciTech Connect

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.

Shinagawa, H.; Terada, N. [National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795 (Japan)

2009-06-16

220

Magnetohydrodynamic instability  

NASA Technical Reports Server (NTRS)

There have been major advances in the theory of magnetic reconnection and of magnetic instability, with important implications for the observations, as follows: (1) Fast and slow magnetic shock waves are produced by the magnetohydrodynamics of reconnection and are potential particle accelerators. (2) The impulsive bursty regime of reconnection gives a rapid release of magnetic energy in a series of bursts. (3) The radiative tearing mode creates cool filamentary structures in the reconnection process. (4) The stability analyses imply that an arcade can become unstable when either its height or twist of plasma pressure become too great.

Priest, E. R.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.

1986-01-01

221

Conceptual design of a coal-fired MHD retrofit plant. Topical report, Seed Regeneration System Study 2  

SciTech Connect

Westinghouse Advanced Energy Systems (WAES), through Contract No. DE-AC22-87PC79668 funded by US DOE/PETC, is conducting a conceptual design study to evaluate a coal-fired magnetohydrodynamic (MHD) retrofit of a utility plant of sufficient size to demonstrate the technical and future economic viability of an MHD system operating within an electric utility environment. The objective of this topical report is to document continuing seed regeneration system application studies and the definition of will system integration requirements for the Scholz MHD retrofit plant design. MHD power plants require the addition of a seeding material in the form of potassium to enhance the ionization of the high temperature combustion gas in the MHD channel. This process has an added environmental advantage compared to other types of coal-fired power plants in that the potassium combines with the naturally occurring sulfur in the coal to form a potassium sulfate flyash (K{sub 2}SO{sub 4}) which can be removed from the process by appropriate particulate control equipment. Up to 100% of the Sulfur in the coal can be removed by this process thereby providing environmentally clean power plant operation that is better than required by present and anticipated future New Source Performance Standards (NSPS).

Not Available

1992-11-01

222

Comparative analysis of the conceptual design studies of potential early commercial MHD power plants (CSPEC)  

NASA Technical Reports Server (NTRS)

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.

Sovie, R. J.; Winter, J. M.; Juhasz, A. J.; Berg, R. D.

1982-01-01

223

Second generation of a rotational electrochemical seismometer using magnetohydrodynamic technology  

NASA Astrophysics Data System (ADS)

Rotational seismometers have many applications. Some require a low self noise with a lower clip specification. Others require many different bandpass specifications, from very low to higher frequencies. The principles of the eentec second-generation R-2 electrochemical triaxial rotational seismometer can achieve many features for various applications. Combining the use of the sophisticated magnetohydrodynamic (MHD) technology increases the current and future features. Principles of the MHD technology used and the many advantages it has in a rotational seismometers are described.

Leugoud, Robert; Kharlamov, Alexei

2012-10-01

224

A Solution-Adaptive Upwind Scheme for Ideal Magnetohydrodynamics  

Microsoft Academic Search

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

Kenneth G. Powell; Philip L. Roe; Timur J. Linde; Tamas I. Gombosi; Darren L. De Zeeuw

1999-01-01

225

Diagnostic instrumentation development program for the heat recovery/seed recovery system of the open-cycle, coal-fired magnetohydrodynamic power plant  

NASA Astrophysics Data System (ADS)

Highly efficient and environmentally acceptable, the coal-fired MHD power plant is an attractive facility for producing electricity. The design of its downstream system, however, presents technological risks which must be corrected if such a plant is to be commercially viable before the end of the century. The heat recovery/seed recovery system (HRSR) at its present stage is vulnerable to corrosion on the gas side of the radiant furnace, the secondary superheater, and the intermediate temperature air heater. Slagging and fouling of the heat transfer surface have yet to be eliminated. Gas chemistry, radiant heat transfer, and particulate removal are other problematic areas which are being researched in a DOE development program whose test activities at three facilities are contributing to an MHD/HRSR data base. In addition, a 20 MWt system to study HRSR design, is being now assembled in Tennessee.

Murphree, D. L.; Cook, R. L.; Bauman, L. E.; Benton, R. D.; Probert, P. B.; Selby, R. C.

1981-01-01

226

Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high-energy-density plasmas  

E-print Network

Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph- quence of pressure-driven, resistive magnetohydrodynamic MHD interchange instabilities. In contrast

227

Possible signatures of nonlinear MHD waves in the solar wind: UVCS observations and models  

NASA Technical Reports Server (NTRS)

Recent ultraviolet coronagraph spectrometer (UVCS) white light channel observations are discussed. These data indicated quasi-periodic variations in the polarized brightness in the polar coronal holes. The Fourier power spectrum analysis showed significant peaks at about six minutes and possible fluctuations on longer time scales. The observations are consistent with the predictions of the nonlinear solitary-like wave model. The purpose of a planned study on plume and inter-plume regions of coronal holes, motivated by the result of a 2.5 magnetohydrodynamic model (MHD), is explained.

Ofman, L.; Romoli, M.; Davila, J. M.; Poletto, G.; Kohl, J.; Noci, G.

1997-01-01

228

System study of an MHD/gas turbine combined-cycle baseload power plant. HTGL report No. 134  

SciTech Connect

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 the MHD exhaust gases by means of metal tube heat exchangers. In addition to the base case systems, vapor cycle variation systems were considered which included the addition of a vapor cycle bottoming plant to improve the thermal efficiency. These systems required a small amount of cooling water. The MHD/gas turbine systems were modeled with sufficient detail, using realistic component specifications and costs, so that the thermal and economic performance of the system could be accurately determined. Three cases of MHD/gas turbine systems were studied, with Case I being similar to an MHD/steam system so that a direct comparison of the performances could be made, with Case II being representative of a second generation MHD system, and with Case III considering oxygen enrichment for early commercial applications. The systems are nominally 800 MW/sub e/ to 1000 MW/sub e/ in size. The results show that the MHD/gas turbine system has very good thermal and economic performances while requiring either little or no cooling water. Compared to the MHD/steam system which has a cooling tower heat load of 720 MW, the Base Case I MHD/gas turbine system has a heat rate which is 13% higher and a cost of electricity which is only 7% higher while requiring no cooling water. Case II results show that an improved performance can be expected from second generation MHD/gas turbine systems. Case III results show that an oxygen enriched MHD/gas turbine system may be attractive for early commercial applications in dry regions of the country.

Annen, K.D.

1981-08-01

229

Reflection Properties of Gravito-MHD Waves in an Inhomogeneous Horizontal Magnetic Field  

NASA Astrophysics Data System (ADS)

We derive the dispersion equation for gravito-magnetohydrodynamical (MHD) waves in an isothermal, gravitationally stratified plasma with a horizontal inhomogeneous magnetic field. Sound and Alfvén speeds are constant. Under these conditions, it is possible to derive analytically the equations for gravito-MHD waves. The high values of the viscous and magnetic Reynolds numbers in the solar atmosphere imply that the dissipative terms in the MHD equations are negligible, except in layers around the positions where the frequency of the MHD wave equals the local Alfvén or slow wave frequency. Outside these layers the MHD waves are accurately described by the equations of ideal MHD.

Jovanovi?, G.

2014-11-01

230

Converging cylindrical shocks in ideal magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

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.

Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

2014-09-01

231

Converging cylindrical shocks in ideal magnetohydrodynamics  

SciTech Connect

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.

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

232

Lyapunov stability analysis of magnetohydrodynamic plasma equilibria with axisymmetric toroidal flow  

Microsoft Academic Search

Lyapunov stability conditions for ideal magnetohydrodynamic (MHD) plasmas with mass flow in axisymmetric toroidal geometry are determined in the Eulerian representation. Axisymmetric equilibrium solutions of ideal MHD are associated to critical points of a nonlinearly conserved Lyapunov functional consisting of the sum of the total energy and the following flux-weighted quantities: the circulation along field lines, the angular momentum, the

Juan Antonio Almaguer; Eliezer Hameiri; Julio Herrera; Darryl D. Holm

1988-01-01

233

Locally Divergence-preserving Upwind Finite Volume Schemes for Magnetohydrodynamic Equations  

Microsoft Academic Search

A main issue in nonstationary, compressible magnetohydrodynamic (MHD) simu- lations is controlling the divergence of the magnetic flux. This paper presents a general procedure showing how to modify the intercell fluxes in a conservative MHD finite volume code such that the scheme becomes locally divergence preserving. That is, a certain discrete divergence operator van- ishes exactly during the entire simulation,

Manuel Torrilhon

2005-01-01

234

Stationary Two-Dimensional Magnetohydrodynamic Flows with Shocks: Characteristic Analysis and Grid Convergence Study  

Microsoft Academic Search

Five model flows of increasing complexity belonging to the class of stationary two-dimensional planar field-aligned magnetohydrodynamic (MHD) flows are presented which are well suited to the quantitative evaluation of MHD codes. The physical properties of these five flows are investigated using characteristic theory. Grid convergence criteria for flows belonging to this class are derived from characteristic theory, and grid convergence

H. De Sterck; A. Cs??k; D. Vanden Abeele; S. Poedts; H. Deconinck

2001-01-01

235

Non-uniform convergence of finite volume schemes for Riemann problems of ideal magnetohydrodynamics  

Microsoft Academic Search

This paper presents Riemann test problems for ideal magnetohydrodynamics (MHD) finite volume schemes. The test problems place emphasis on the hyperbolic irregularities of the ideal MHD system, namely the occurrence of intermediate shocks and non-unique solutions. We investigate numerical solutions for the test problems obtained by several commonly used methods (Roe, HLLE, central scheme). All methods turned out to show

M. Torrilhon

2003-01-01

236

MHD coal-fired flow facility. Annual technical progress report, October 1979-September 1980  

SciTech Connect

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).

Alstatt, M.C.; Attig, R.C.; Brosnan, D.A.

1981-03-01

237

Steady-state axisymmetric nonlinear magnetohydrodynamic solutions with various boundary conditions  

NASA Astrophysics Data System (ADS)

Axisymmetric magnetohydrodynamics (MHD) can be invoked for describing astrophysical magnetized flows and formulated to model stellar magnetospheres including main-sequence stars (e.g. the Sun), compact stellar objects [e.g. magnetic white dwarfs (MWDs), radio pulsars, anomalous X-ray pulsars, magnetars, isolated neutron stars, etc.] and planets as a major step forward towards a full three-dimensional model construction. Using powerful and reliable numerical solvers based on two distinct finite-difference method and finite-element method schemes of algorithm, we examine axisymmetric steady-state or stationary MHD models in Throumoulopoulos & Tasso, finding that their separable semi-analytic non-linear solutions are actually not unique given their specific selection of several free functionals and chosen boundary conditions. Similar situations of multiple non-linear solutions with the same boundary conditions actually also happen to force-free magnetic field models of Low & Lou. The multiplicity of non-linear steady MHD solutions gives rise to differences in the total energies contained in the magnetic fields and flow velocity fields as well as in the asymptotic behaviours approaching infinity, which may in turn explain why numerical solvers tend to converge to a non-linear solution with a lower energy than the corresponding separable semi-analytic one. By properly adjusting model parameters, we invoke semi-analytic and numerical solutions to describe different kinds of scenarios, including nearly parallel case and the situation in which the misalignment between the plasma flow and magnetic field is considerable. We propose that these MHD models are capable of describing the magnetospheres of MWDs as examples of applications with moderate conditions (including magnetic field) where the typical values of several important parameters are consistent with observations. Physical parameters can also be estimated based on such MHD models directly. We discuss the challenges of developing numerical extrapolation MHD codes in view of the non-linear degeneracy.

Wang, Lile; Lou, Yu-Qing

2014-04-01

238

Global Magnetohydrodynamic Modeling of the Solar Corona  

NASA Astrophysics Data System (ADS)

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.

Linker, Jon A.

1997-02-01

239

Global Magnetohydrodynamic Modeling of the Solar Corona  

NASA Technical Reports Server (NTRS)

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.

Linker, Jon A.

1997-01-01

240

Statistical Theory of Magnetohydrodynamic Turbulence: Recent Results  

E-print Network

In this review article we will describe recent developments in statistical theory of magnetohydrodynamic (MHD) turbulence. Kraichnan and Iroshnikov first proposed a phenomenology of MHD turbulence where Alfven time-scale dominates the dynamics, and the energy spectrum E(k) is proportional to k^{-3/2}. In the last decade, many numerical simulations show that spectral index is closer to 5/3, which is Kolmogorov's index for fluid turbulence. We review recent theoretical results based on anisotropy and Renormalization Groups which support Kolmogorov's scaling for MHD turbulence. Energy transfer among Fourier modes, energy flux, and shell-to-shell energy transfers are important quantities in MHD turbulence. We report recent numerical and field-theoretic results in this area. Role of these quantities in magnetic field amplification (dynamo) are also discussed. There are new insights into the role of magnetic helicity in turbulence evolution. Recent interesting results in intermittency, large-eddy simulations, and shell models of magnetohydrodynamics are also covered.

Mahendra K. Verma

2004-04-26

241

Solar wind turbulence from MHD to sub-ion scales: high-resolution hybrid simulations  

E-print Network

We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wave numbers. The simulation results exhibit simultaneously several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magneto-hydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and the parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm's law.

Franci, Luca; Matteini, Lorenzo; Landi, Simone; Hellinger, Petr

2015-01-01

242

The generation and damping of propagating MHD kink waves in the solar atmosphere  

E-print Network

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 kilometres per second is still unclear. One such mechanism for providing the required energy flux is incompressible torsional Alfv\\'en 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 unclear. 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 an...

Morton, R J; Hillier, A; Erdélyi, R

2013-01-01

243

Gas Core Reactor Numerical Simulation Using a Coupled MHD-MCNP Model  

NASA Technical Reports Server (NTRS)

Analysis is provided in this report of using two head-on magnetohydrodynamic (MHD) shocks to achieve supercritical nuclear fission in an axially elongated cylinder filled with UF4 gas as an energy source for deep space missions. The motivation for each aspect of the design is explained and supported by theory and numerical simulations. A subsequent report will provide detail on relevant experimental work to validate the concept. Here the focus is on the theory of and simulations for the proposed gas core reactor conceptual design from the onset of shock generations to the supercritical state achieved when the shocks collide. The MHD model is coupled to a standard nuclear code (MCNP) to observe the neutron flux and fission power attributed to the supercritical state brought about by the shock collisions. Throughout the modeling, realistic parameters are used for the initial ambient gaseous state and currents to ensure a resulting supercritical state upon shock collisions.

Kazeminezhad, F.; Anghaie, S.

2008-01-01

244

Action principles for extended magnetohydrodynamic models  

SciTech Connect

The general, non-dissipative, two-fluid model in plasma physics is Hamiltonian, but this property is sometimes lost or obscured in the process of deriving simplified (or reduced) two-fluid or one-fluid models from the two-fluid equations of motion. To ensure that the reduced models are Hamiltonian, we start with the general two-fluid action functional, and make all the approximations, changes of variables, and expansions directly within the action context. The resulting equations are then mapped to the Eulerian fluid variables using a novel nonlocal Lagrange-Euler map. Using this method, we recover Lüst's general two-fluid model, extended magnetohydrodynamic (MHD), Hall MHD, and electron MHD from a unified framework. The variational formulation allows us to use Noether's theorem to derive conserved quantities for each symmetry of the action.

Keramidas Charidakos, I.; Lingam, M.; Morrison, P. J.; White, R. L. [Institute for Fusion Studies and Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Wurm, A. [Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts 01119 (United States)

2014-09-15

245

Action principles for extended magnetohydrodynamic models  

NASA Astrophysics Data System (ADS)

The general, non-dissipative, two-fluid model in plasma physics is Hamiltonian, but this property is sometimes lost or obscured in the process of deriving simplified (or reduced) two-fluid or one-fluid models from the two-fluid equations of motion. To ensure that the reduced models are Hamiltonian, we start with the general two-fluid action functional, and make all the approximations, changes of variables, and expansions directly within the action context. The resulting equations are then mapped to the Eulerian fluid variables using a novel nonlocal Lagrange-Euler map. Using this method, we recover Lüst's general two-fluid model, extended magnetohydrodynamic (MHD), Hall MHD, and electron MHD from a unified framework. The variational formulation allows us to use Noether's theorem to derive conserved quantities for each symmetry of the action.

Keramidas Charidakos, I.; Lingam, M.; Morrison, P. J.; White, R. L.; Wurm, A.

2014-09-01

246

Sea-water magnetohydrodynamic propulsion for next-generation undersea vehicles. Annual report, 1 February 1989-31 January 1990  

SciTech Connect

Three tasks were performed in this report period. Their individual abstracts are summarized as follows: (I) Thruster Performance Modelings - The purpose of this work is to analyze underwater vehicle propulsion by applying Lorentz forces to the surrounding sea water. While this propulsion concept involves two different schemes, i.e. the external field method and the internal duct-type method, the current analysis focuses on the internal thruster scheme due to the space limitations and speed considerations. The theories of magnetohydrodynamic (MHD) pump jet propulsion are discussed. A so-called dual control volume analysis to model the MHD thruster, and calculations of vehicle velocity and power efficiency are presented. (II) Sea Water Conductivity Enhancement - This work discusses the mechanisms of enhancing the electric conductivity of sea water. The direct impact of conductivity enhancement of sea water is the improvement of propulsion performances of marine vehicles that use the magnetohydrodynamic thrusts of sea water. The performance improvement can be in energy efficiency or in vehicle speed. Injection of strong electrolytes (acids or bases) into the main sea water flow in the MHD channel appeared to be the most logical way of achieving the purpose. (III) Status of Current Superconductivity Works - A survey of recent research in both low -T{sub c} and high -T{sub c} superconductivities is provided. It is generally true that high -T{sub c} superconductors carry critical current densities several orders of magnitude less than those of low -T{sub c} ones.

Lin, T.F.; Gilbert, J.B.; Kossowsky, R.

1990-02-01

247

Computation of multi-region relaxed magnetohydrodynamic equilibria  

SciTech Connect

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.

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

248

Basic properties of magnetohydrodynamic turbulence in the inertial range  

NASA Astrophysics Data System (ADS)

We revisit the issue of the spectral slope of magnetohydrodynamic (MHD) turbulence in the inertial range and argue that the numerics favour a Goldreich-Sridhar -5/3 slope rather than a -3/2 slope. We also perform precision measurements of the anisotropy of MHD turbulence and determine the anisotropy constant CA= 0.34 of Alfvénic turbulence. Together with the previously measured Kolmogorov constant CK= 4.2, or 3.3 for a purely Alfvénic case, it constitutes a full description of the MHD cascade in terms of spectral quantities, which is of high practical value for astrophysics.

Beresnyak, Andrey

2012-06-01

249

Computation of Multi-region Relaxed Magnetohydrodynamic Equilibria  

SciTech Connect

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.

S.R. Hudson, R.L. Dewar, G. Dennis, M.J. Hole, M. McGann, G. von Nessi and S. Lazerson

2013-03-29

250

Magnetohydrodynamic turbulence: Generalized formulation and extension to compressible cases  

SciTech Connect

A general framework that incorporates the Iroshnikov-Kraichnan (IK) and Goldreich-Sridhar (GS) phenomenalogies of magnetohydrodynamic (MHD) turbulence is developed. This affords a clarification of the regimes of validity of the IK and GS models and hence help resolve some controversies on this aspect. This general formulation appears to have a certain robustness as revealed here by its form invariance with respect to inclusion of compressible effects. Generalizations of the IK and GS spectra to compressible MHD turbulence are given. These two branches are shown to merge with the MHD shockwave spectrum, as to be expected, in the infinite compressibility limit.

Shivamoggi, Bhimsen K. [University of Central Florida, Mathematics, 4000 Central Florida Blvd., Orlando, FL 32816-1364 (United States)], E-mail: bhimsens@mail.ucf.edu

2008-06-15

251

The role of magnetohydrodynamics in heliospheric space plasma physics research  

Microsoft Academic Search

Magnetohydrodynamics (MHD) is a fairly recent extension of the field of fluid mechanics. While much remains to be done, it has successfully been applied to the contemporary field of heliospheric space plasma research to evaluate the ‘macroscopic picture’ of some vital topics via the use of conducting fluid equations and numerical modeling and simulations. Some representative examples from solar and

Murray Dryer; Zdenka Kopal Smith; Shi Tsan Wu

1988-01-01

252

Disk MHD generator study  

NASA Technical Reports Server (NTRS)

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.

Retallick, F. D.

1980-01-01

253

Supersonic regime of the Hall-magnetohydrodynamics resistive tearing instability  

SciTech Connect

An earlier analysis of the Hall-magnetohydrodynamics (MHD) tearing instability [E. Ahedo and J. J. Ramos, Plasma Phys. Controlled Fusion 51, 055018 (2009)] is extended to cover the regime where the growth rate becomes comparable or exceeds the sound frequency. Like in the previous subsonic work, a resistive, two-fluid Hall-MHD model with massless electrons and zero-Larmor-radius ions is adopted and a linear stability analysis about a force-free equilibrium in slab geometry is carried out. A salient feature of this supersonic regime is that the mode eigenfunctions become intrinsically complex, but the growth rate remains purely real. Even more interestingly, the dispersion relation remains of the same form as in the subsonic regime for any value of the instability Mach number, provided only that the ion skin depth is sufficiently small for the mode ion inertial layer width to be smaller than the macroscopic lengths, a generous bound that scales like a positive power of the Lundquist number.

Ahedo, Eduardo [Universidad Politecnica de Madrid, 28040 Madrid (Spain); Ramos, Jesus J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2012-07-15

254

Magnetohydrodynamic electrochemistry in the field of Nd-Fe-B magnets. Theory, experiment, and application in self-powered flow delivery systems.  

PubMed

Nd-Fe-B permanent magnets are easily available, powerful, and inexpensive and generate strong quantifiable convective effects during electrolysis, similar to those obtained with rotating electrodes or large electromagnets. The magnetic field of Nd-Fe-B magnets has been simulated numerically and mapped. Its most characteristic difference from the field of most commercial electromagnets is the presence of magnetic field gradients, which introduce additional body forces in the electrolytic solution and create new modes of mass transfer due to the attraction of electrogenerated radicals into areas of stronger field. The effect of those new forces on the radial distribution of the flow profile in the vicinity of the electrode has been monitored with generation-collection experiments and optical photography. The emerging utility of Nd-Fe-B magnets in systems of chemical interest is demonstrated with flow control and delivery devices, based on galvanic cells configured as self-powered magnetohydrodynamic pumps. PMID:11534726

Leventis, N; Gao, X

2001-08-15

255

Magnetohydrodynamics Accelerator Research into Advanced Hypersonics (MARIAH). Part 2  

NASA Technical Reports Server (NTRS)

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.

Baughman, Jack A.; Micheletti, David A.; Nelson, Gordon L.; Simmons, Gloyd A.

1997-01-01

256

Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH). Part 1  

NASA Technical Reports Server (NTRS)

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.

Micheletti, David A.; Baughman, Jack A.; Nelson, Gordon L.; Simmons, Gloyd A.

1997-01-01

257

Coronal magnetohydrodynamic waves and oscillations: observations and quests.  

PubMed

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

Aschwanden, Markus J

2006-02-15

258

Coherent Eigenmodes in Homogeneous MHD Turbulence  

NASA Technical Reports Server (NTRS)

The statistical mechanics of Fourier models of ideal, homogeneous, incompressible magnetohydrodynamic (MHD) turbulence is discussed, along with their relevance for dissipative magnetofluids. Although statistical theory predicts that Fourier coefficients of fluid velocity and magnetic field are zero-mean random variables, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation, i.e., we have coherent structure. We use eigenanalysis of the modal covariance matrices in the probability density function to explain this phenomena in terms of `broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We provide examples from 2-D and 3-D magnetohydrodynamic simulations of homogeneous turbulence, and show new results from long-time simulations of MHD turbulence with and without a mean magnetic field

Shebalin, John V.

2010-01-01

259

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

Microsoft Academic Search

A set of generalized magnetohydrodynamic (MHD) equations is formulated to accommodate the effects associated with high ion and electron temperatures in high-performance plasmas in tokamaks. The effects of neoclassical bootstrap current, neoclassical ion viscosity, the ion finite Larmor radius effect and electron and ion drift effects are taken into account in two-fluid MHD equations together with gyroviscosity, parallel viscosity, electron

A. B. Mikhailovskii

1998-01-01

260

Collisional and viscous damping of MHD waves in partially ionized plasmas of the solar atmosphere  

Microsoft Academic Search

Magnetohydrodynamic (MHD) waves are widely considered as a possible source of heating for various parts of the outer solar atmosphere. Among the main energy dissipation mechanisms which convert the energy of damped MHD waves into thermal energy are collisional dissipation (resistivity) and viscosity. The presence of neutral atoms in the partially ionized plasmas of the solar photosphere, chromosphere and prominences

M. L. Khodachenko; T. D. Arber; H. O. Rucker; A. Hanslmeier

2004-01-01

261

Report on the MHD performance demonstration experiment, October 1, 1979September 30, 1980  

Microsoft Academic Search

The Arnold Engineering Development Center (AEDC) has been under contract with the Dept. of Energy (DOE) since December 1973 to modify existing equipment, install new hardware, and 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 the projected

R. F. Starr; L. S. Christensen; G. L. Whitehead; G. W. Garrison; B. L. Seiber; R. L. Lowry

1980-01-01

262

CELLULAR AUTOMATA MODELS AND MHD APPROACH IN THE CONTEXT OF SOLAR FLARES 1  

E-print Network

CELLULAR AUTOMATA MODELS AND MHD APPROACH IN THE CONTEXT OF SOLAR FLARES 1 Anastasios Anastasiadis for the case of solar flares, and compare it to the magnetohydrodynamic (MHD) theory. We consider solar flares the observed statistical properties of solar flaring activity. In Section 2. the basic results

Anastasiadis, Anastasios

263

Locally Divergence-Free Central Discontinuous Galerkin Methods for Ideal MHD Sergey Yakovlev1  

E-print Network

Locally Divergence-Free Central Discontinuous Galerkin Methods for Ideal MHD Equations Sergey a family of locally divergence-free central discontinuous Galerkin methods for ideal magnetohydrodynamic (MHD) equations. The methods are based on the original central discontinuous Galerkin methods (SIAM

Li, Fengyan

264

RESONANCE BROADENING AND HEATING OF CHARGED PARTICLES IN MAGNETOHYDRODYNAMIC TURBULENCE  

SciTech Connect

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.

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

265

Energetic Particles and Magnetohydrodynamic Activity in SSX  

NASA Astrophysics Data System (ADS)

Results from the Swarthmore Spheromak Experiment (SSX) indicate that formation and partial merging of two spheromak plasmas can be described well by a magnetohydrodynamic (MHD) picture in which there is substantial evolution towards force free states within each vessel, while reconnection activity, also described reasonably well by MHD, occurs in the region of interaction. MHD simulations (Lukin et al, Phys. Plasmas, 2001) support and provide further detail to this interpretation. In the present study, test particle equations are integrated using MHD data from SSX simulations to further understand the energetic particle fluxes that are observed experimentally. The test particle simulation is run with dimensionless parameters similar to the experiment, and particles are permitted to escape when they encounter the simulated SSX boundaries. MHD activity related to reconnection is responsible for accelerating charged particles. The process includes two phases -- a strong but short duration direct acceleration in the quasi-steady reconnection electric field, and a weaker longer lived stochastic component associated with turbulence. (Research supported by the USDOE under grant ER54490, and by NSF under grant ATM-9713595)

Matthaeus, W. H.; Qin, G.; Lukin, V. S.; Brown, M. R.

2001-05-01

266

Perfect magnetohydrodynamics as a field theory  

SciTech Connect

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.

Bekenstein, Jacob D.; Betschart, Gerold [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

2006-10-15

267

Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft  

SciTech Connect

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.

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

268

Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft  

NASA Astrophysics Data System (ADS)

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.

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

2004-03-01

269

Solar Flares: Magnetohydrodynamic Processes  

NASA Astrophysics Data System (ADS)

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.

Shibata, Kazunari; Magara, Tetsuya

2011-12-01

270

Modeling the Earth's Magnetosphere using Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

This thesis describes work on building numerical models of the Earth's magnetosphere using magnetohydrodynamics (MHD) and other related modeling methods. For many years, models that solve the MHD equations have been the main tool for improving our theoretical understanding of the large-scale dynamics of the Earth's magnetosphere. While the MHD models have been very successful in capturing many large-scale features, they fail to adequately represent the important drift physics in the inner magnetosphere. Consequently, the ring current, which contains most of the particle energy in the inner magnetosphere, is not realistically represented in MHD models. In this thesis, Chapter 2 and 3 will describe in detail our effort to couple the OpenGGCM (Open Geospace General Circulation Model), one of the major MHD models, to the Rice Convection Model (RCM), an inner magnetosphere ring current model, with the goal of including energy dependent drift physics into the MHD model. In Chapter 4, we will describe an initial attempt to use a direct-integration method to calculate Birkeland currents in the MHD code. Another focus of the thesis work, presented in Chapter 5, addresses a longstanding problem on how a geomagnetic substorm can occur within the closed field line region of the tail. We find a scenario of a bubble-blob pair formation in an OpenGGCM simulation just before the expansion phase of the substorm begins and the subsequent separation of the bubble and the blob decreases the normal component of the magnetic field until finally an X-line occurs. Thus the formation of the bubble-blob pair may play an important role in changing the magnetospheric configuration from a stretched field to the X-line formation that is believed to be the major signature of a substorm.

Hu, Bei

271

Development of Liquid-Vapor Core Reactors with MHD Generator for Space Power and Propulsion Applications  

SciTech Connect

Any reactor that utilizes fuel consisting of a fissile material in a gaseous state may be referred to as a gaseous core reactor (GCR). Studies on GCRs have primarily been limited to the conceptual phase, mostly due to budget cuts and program cancellations in the early 1970's. A few scientific experiments have been conducted on candidate concepts, primarily of static pressure fissile gas filling a cylindrical or spherical cavity surrounded by a moderating shell, such as beryllium, heavy water, or graphite. The main interest in this area of nuclear power generation is for space applications. The interest in space applications has developed due to the promise of significant enhancement in fuel utilization, safety, plant efficiency, special high-performance features, load-following capabilities, power conversion optimization, and other key aspects of nuclear power generation. The design of a successful GCR adapted for use in space is complicated. The fissile material studied in the pa st has been in a fluorine compound, either a tetrafluoride or a hexafluoride. Both of these molecules have an impact on the structural material used in the making of a GCR. Uranium hexafluoride as a fuel allows for a lower operating temperature, but at temperatures greater than 900K becomes essentially impossible to contain. This difficulty with the use of UF6 has caused engineers and scientists to use uranium tetrafluoride, which is a more stable molecule but has the disadvantage of requiring significantly higher operating temperatures. Gas core reactors have traditionally been studied in a steady state configuration. In this manner a fissile gas and working fluid are introduced into the core, called a cavity, that is surrounded by a reflector constructed of materials such as Be or BeO. These reactors have often been described as cavity reactors because the density of the fissile gas is low and criticality is achieved only by means of the reflector to reduce neutron leakage from the core. Still there are problems of containment since many of the proposed vessel materials such as W or Mo have high neutron cross sections making the design of a critical system difficult. There is also the possibility for a GCR to remain in a subcritical state, and by the use of a shockwave mechanism, increase the pressure and temperature inside the core to achieve criticality. This type of GCR is referred to as a shockwave-driven pulsed gas core reactor. These two basic designs were evaluated as advance concepts for space power and propulsion.

Samim Anghaie

2002-08-13

272

Magnetohydrodynamics of Chiral Relativistic Fluids  

E-print Network

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.

Boyarsky, Alexey; Ruchayskiy, Oleg

2015-01-01

273

ANALYTIC APPROXIMATE SEISMOLOGY OF PROPAGATING MAGNETOHYDRODYNAMIC WAVES IN THE SOLAR CORONA  

SciTech Connect

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.

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

274

Enthalpy augmentation to MHD generation. [electric arc discharge in combustor  

Microsoft Academic Search

An improved magnetohydrodynamic (MHD) generator is provided by increasing the electrical conductivity of the working fluid by raising the temperature of the fluid. This is accomplished by providing an additional source of heat for the combustion products within the combustor. The additional source of heat in the combustor is provided by an electrical arc discharge within the combustor. The arc

Holt

1977-01-01

275

The superconducting MHD-propelled ship YAMATO1  

Microsoft Academic Search

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

Yohei Sasakawa; Setsuo Takezawa; Yoshinori Sugawara; Yoshihiro Kyotani

1995-01-01

276

MHD--Developing New Technology to Meet the Energy Crisis  

ERIC Educational Resources Information Center

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)

Fitch, Sandra S.

1978-01-01

277

Laser production and heating of plasma for MHD application  

NASA Technical Reports Server (NTRS)

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 CO2 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 CO2 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 CO2 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.

Jalufka, N. W.

1988-01-01

278

Laser production and heating of plasma for MHD application  

SciTech Connect

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.

Jalufka, N.W.

1988-03-01

279

On the question of hysteresis in Hall magnetohydrodynamic reconnection  

SciTech Connect

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.

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

280

Compression of magnetohydrodynamic simulation data using singular value decomposition  

SciTech Connect

Numerical calculations of magnetic and flow fields in magnetohydrodynamic (MHD) simulations can result in extensive data sets. Particle-based calculations in these MHD fields, needed to provide closure relations for the MHD equations, will require communication of this data to multiple processors and rapid interpolation at numerous particle orbit positions. To facilitate this analysis it is advantageous to compress the data using singular value decomposition (SVD, or principal orthogonal decomposition, POD) methods. As an example of the compression technique, SVD is applied to magnetic field data arising from a dynamic nonlinear MHD code. The performance of the SVD compression algorithm is analyzed by calculating Poincare plots for electron orbits in a three-dimensional magnetic field and comparing the results with uncompressed data.

Castillo Negrete, D. del [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hirshman, S.P. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)]. E-mail: hirshmansp@ornl.gov; Spong, D.A. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); D'Azevedo, E.F. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2007-03-01

281

The complete set of Casimirs in Hall-magnetohydrodynamics  

SciTech Connect

A procedure for determining all the Casimir constants of motion in magnetohydrodynamics (MHD) [E. Hameiri, Phys. Plasmas 11, 3423 (2004)] is extended to Hall-MHD. We obtain and solve differential equations for the variational derivatives of all the Casimirs, which must be satisfied for any dynamically accessible motion in Hall-MHD. In an extension of the more commonly considered Hall-MHD model, we also include the electron fluid entropy. The most interesting case for plasma confinement, which is usually true for axisymmetric configurations but desirable in general, is when both the magnetic field and the ion velocity field form the two separate families of nested toroidal surfaces. The Casimirs are then three functionals for each surface, involving the fluxes of certain vector fields and the number of particles contained in each. We also determine a family of independent Casimirs in a general configuration.

Kawazura, Yohei [Graduate School of Frontier Sciences, University of Tokyo Kashiwa, Chiba 277-8561 (Japan); Hameiri, Eliezer [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)

2012-08-15

282

Time-resolved observation of discrete and continuous magnetohydrodynamic dynamo in the reversed-field pinch edge  

SciTech Connect

We report the first experimental verification of the magnetohydrodynamic (MHD) dynamo in the reversed-field pinch (RFP). A burst of MHD dynamo electric field is observed during the sawtooth crash, followed by an increase in the local parallel current in the Madison Symmetric Totus RFP edge. By measuring each term, the parallel MHD mean-field Ohm's law is observed to hold within experimental error bars both between and during sawtooth crashes.

Ji, H.; Almagri, A.F.; Prager, S.C.; Sarff, J.S. (Department of Physics, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States))

1994-08-01

283

Magnetohydrodynamic Modeling of the Jovian Magnetosphere  

NASA Technical Reports Server (NTRS)

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.

Walker, Raymond

2005-01-01

284

Numerical Methods for Radiation Magnetohydrodynamics in Astrophysics  

SciTech Connect

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.

Klein, R I; Stone, J M

2007-11-20

285

Advected Invariants in Magnetohydrodynamics and Gas Dynamics  

NASA Astrophysics Data System (ADS)

In this paper we discuss conservation laws in ideal magnetohydrodynamics (MHD) and gas dynamics associated with advected invariants. The invariants in some cases, can be related to fluid relabelling symmetries associated with the Lagrangian map. There are different classes of invariants that are advected or Lie dragged with the flow. Simple examples are the advection of the entropy S (a 0-form), and the conservation of magnetic flux (an invariant 2-form advected with the flow). The magnetic flux conservation law is equivalent to Faraday's equation. We discuss the gauge condition required for the magnetic helicity to be advected with the flow. The conditions for the cross helicity to be an invariant are discussed. We discuss the different variants of helicity in fluid dynamics and in MHD, including: fluid kinetic helicity, cross helicity, magnetic helicity, Ertel's theorem and potential vorticity, the Hollman invariant, and the Godbillon Vey invariant for special flows for which the magnetic helicity is zero.

Webb, G. M.; Hu, Q.; McKenzie, J. F.; Dasgupta, B.; Zank, G. P.

2014-05-01

286

Magnetohydrodynamic ship propulsion with superconducting magnets  

SciTech Connect

The feasibility of magnetohydrodynamic (MHD) ship propulsion using superconducting magnets is reviewed in light of recent advances in high-temperature superconductivity. The scaling relations for the electrical and hydraulic efficiencies of MHD pump-jets show that overall efficiencies > 50% are feasible at speeds of 40 knots and higher provided that magnetic fields > 5 T can be maintained over volumes of the order of 100 m/sup 3/. The development of large-scale electrical machinery and magnets using the high-temperature superconductors now under development could make it practical to construct submersibles for high-speed and silent operation. Low-speed tankers for movement of bulk cargo would be efficient with even lower fields.

Mitchell, D.L.; Gubser, D.U.

1988-12-01

287

MHD Development in FLAG  

NASA Astrophysics Data System (ADS)

FLAG is a arbitrary polyhedral, rad-hydro, multi-fluid ALE code for modeling HEDP. A 1D/2D resistive MHD capability is implemented within FLAG to provide a predictive tool for modeling the driver and loads of pulsed power experiments that measure material properties in intense conditions. An overview of the FLAG MHD model is presented with verification results. Mimetic differencing schemes are methods that create discrete versions of PDE operators while preserving physical and geometric properties of the continuous operators [1]. Results are demonstrated for a Mimetic differencing approach to magnetic field diffusion and Joule heating. [4pt] [1] Brezzi, Lipnikov, Simoncini, M3AS: Math Mod and Methds in Ap Sci 15, 10

Reynolds, James; Lipnikov, Konstantin; Rousculp, Christopher; Kaul, Ann; Peterson, Jeff; Nelson, Eric; Gianakon, Thomas

2011-11-01

288

MHD Space Sailing  

E-print Network

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 [1] 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.

T. Kisiel; M. Soida

2007-12-10

289

Modeling extreme "Carrington-type" space weather events using three-dimensional global MHD simulations  

NASA Astrophysics Data System (ADS)

There is a growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure. In the last two decades, significant progress has been made toward the first-principles modeling of space weather events, and three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, thereby playing a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for the modern global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events with a Dst footprint comparable to the Carrington superstorm of September 1859 based on the estimate by Tsurutani et. al. (2003). Results are presented for a simulation run with "very extreme" constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated induced geoelectric field on the ground to such extreme driving conditions. The model setup is further tested using input data for an observed space weather event of Halloween storm October 2003 to verify the MHD model consistence and to draw additional guidance for future work. This extreme space weather MHD model setup is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in ground-based conductor systems such as power transmission grids. Therefore, our ultimate goal is to explore the level of geoelectric fields that can be induced from an assumed storm of the reported magnitude, i.e., Dst˜=-1600 nT.

Ngwira, Chigomezyo M.; Pulkkinen, Antti; Kuznetsova, Maria M.; Glocer, Alex

2014-06-01

290

Simulations of Incompressible MHD Turbulence  

E-print Network

We simulate incompressible MHD turbulence in the presence of a strong background magnetic field. Our major conclusions are: 1) MHD turbulence is most conveniently described in terms of counter propagating shear Alfven and slow waves. Shear Alfven waves control the cascade dynamics. Slow waves play a passive role and adopt the spectrum set by the shear Alfven waves, as does a passive scalar. 2) MHD turbulence is anisotropic with energy cascading more rapidly along k_perp than along k_parallel, where k_perp and k_parallel refer to wavevector components perpendicular and parallel to the local magnetic field. Anisotropy increases with increasing k_perp. 3) MHD turbulence is generically strong in the sense that the waves which comprise it suffer order unity distortions on timescales comparable to their periods. Nevertheless, turbulent fluctuations are small deep inside the inertial range compared to the background field. 4) Decaying MHD turbulence is unstable to an increase of the imbalance between the flux of waves propagating in opposite directions along the magnetic field. 5) Items 1-4 lend support to the model of strong MHD turbulence by Goldreich & Sridhar (GS). Results from our simulations are also consistent with the GS prediction gamma=2/3. The sole notable discrepancy is that 1D power law spectra, E(k_perp) ~ k_perp^{-alpha}, determined from our simulations exhibit alpha ~ 3/2, whereas the GS model predicts alpha = 5/3.

Jason Maron; Peter Goldreich

2001-03-07

291

Energy of eigenmodes in magnetohydrodynamic flows of ideal fluids  

SciTech Connect

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.

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

292

Magnetohydrodynamic waves and coronal seismology: an overview of recent results.  

PubMed

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

De Moortel, Ineke; Nakariakov, Valery M

2012-07-13

293

MHD-induced Energetic Ion Loss during H-mode Discharges in the National Spherical Torus Experiment (NSTX)  

SciTech Connect

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.

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

294

Fusion Engineering and Design 81 (2006) 549553 Numerical analysis of MHD flow and heat transfer in a  

E-print Network

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

Abdou, Mohamed

295

Phurbas: An Adaptive, Lagrangian, Meshless, Magnetohydrodynamics Code. II. Implementation and Tests  

E-print Network

We present the parallel implementation and test problem results for Phurbas, an implementation of an algorithm for simulating the equations of ideal magnetohydrodynamics and other systems of differential equations on an unstructured mesh represented by sample particles. The particles move with the fluid, so the time step is not limited by the Eulerian Courant-Friedrichs-Lewy condition. Full spatial adaptivity is required for stability, and gives the algorithm substantial flexibility and power. A target resolution is specified for each point in space, with particles being added and deleted as needed to meet this target. We have parallelized the code by adapting the framework provided by Gadget-2 (Springel 2005). A set of standard test problems, including 1e-6 amplitude linear MHD waves, magnetized shock tubes, and Kelvin-Helmholtz instabilities yield results that appear competitive with third order grid codes. Finally we demonstrate good agreement with analytic predictions of linear growth rates for magnetorot...

McNally, Colin P; Mac Low, Mordecai-Mark

2011-01-01

296

Magnetic levitation and MHD propulsion  

NASA Astrophysics Data System (ADS)

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

Tixador, P.

1994-04-01

297

Magnetohydrodynamic turbulence in supernova remnants  

E-print Network

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.

Nirupam Roy; Somnath Bharadwaj; Prasun Dutta; Jayaram N. Chengalur

2009-07-23

298

Prospects for Nuclear Electric Propulsion Using Closed-Cycle Magnetohydrodynamic Energy Conversion  

NASA Technical Reports Server (NTRS)

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.

Litchford, R. J.; Bitteker, L. J.; Jones, J. E.

2001-01-01

299

Temporal and Spatial Turbulent Spectra of MHD Plasma and an Observation of Variance Anisotropy  

NASA Astrophysics Data System (ADS)

The nature of magnetohydrodynamic (MHD) turbulence is analyzed through both temporal and spatial magnetic fluctuation spectra. A magnetically turbulent plasma is produced in the MHD wind tunnel configuration of the Swarthmore Spheromak Experiment. The power of magnetic fluctuations is projected into directions perpendicular and parallel to a local mean field; the ratio of these quantities shows the presence of variance anisotropy which varies as a function of frequency. Comparisons among magnetic, velocity, and density spectra are also made, demonstrating that the energy of the turbulence observed is primarily seeded by magnetic fields created during plasma production. Direct spatial spectra are constructed using multi-channel diagnostics and are used to compare to frequency spectra converted to spatial scales using the Taylor hypothesis. Evidence for the observation of dissipation due to ion inertial length scale physics is also discussed, as well as the role laboratory experiments can play in understanding turbulence typically studied in space settings such as the solar wind. Finally, all turbulence results are shown to compare fairly well to a Hall-MHD simulation of the experiment.

Schaffner, D. A.; Brown, M. R.; Lukin, V. S.

2014-08-01

300

Development and validation of a magneto-hydrodynamic solver for blood flow analysis  

NASA Astrophysics Data System (ADS)

The objective of this study was to develop a numerical solver to calculate the magneto-hydrodynamic (MHD) signal produced by a moving conductive liquid, i.e. blood flow in the great vessels of the heart, in a static magnetic field. We believe that this MHD signal is able to non-invasively characterize cardiac blood flow in order to supplement the present non-invasive techniques for the assessment of heart failure conditions. The MHD signal can be recorded on the electrocardiogram (ECG) while the subject is exposed to a strong static magnetic field. The MHD signal can only be measured indirectly as a combination of the heart's electrical signal and the MHD signal. The MHD signal itself is caused by induced electrical currents in the blood due to the moving of the blood in the magnetic field. To characterize and eventually optimize MHD measurements, we developed a MHD solver based on a finite element code. This code was validated against literature, experimental and analytical data. The validation of the MHD solver shows good agreement with all three reference values. Future studies will include the calculation of the MHD signals for anatomical models. We will vary the orientation of the static magnetic field to determine an optimized location for the measurement of the MHD blood flow signal.

Kainz, W.; Guag, J.; Benkler, S.; Szczerba, D.; Neufeld, E.; Krauthamer, V.; Myklebust, J.; Bassen, H.; Chang, I.; Chavannes, N.; Kim, J. H.; Sarntinoranont, M.; Kuster, N.

2010-12-01

301

Numerical Simulation of 2D Supersonic Magnetohydrodynamic Channel and Study on Hall Effect  

Microsoft Academic Search

In this research effort, numerical simulation of two-dimensional magnetohydrodynamic (MHD) channel is performed and Hall effect is studied. The computational model consists of the Navier-Stokes (N-S) equations coupled with electrical-magnetic source terms, Maxwell equations and the generalized Ohm's law. Boundary conditions for the electrical potential equation considering Hall effect are derived. To start with, the MHD channel with single-pair electrodes

Xiaomei ZHENG; Haoyu LU; Dajun XU; Guobiao CAI

2011-01-01

302

Time-resolved observation of discrete and continuous MHD dynamo in the reversed-field pinch edge  

SciTech Connect

We report the first experimental verification of the MHD dynamo in the RFP. A burst of magnetohydrodynamic (MHD) dynamo electric field is observed during the sawtooth crash, followed by an increase in the local parallel current in the MST RFP edge. By measuring each term, the parallel MHD mean-field Ohm`s law is observed to hold within experimental error bars both between and during sawtooth crashes.

Ji, H.; Almagri, A.F.; Prager, S.C.; Sarff, J.S.

1994-01-06

303

Numerical Study of Relativistic Magnetohydrodynamic Reconnection and its Radiative Effects  

NASA Astrophysics Data System (ADS)

The dynamical impacts of radiation fields on the relativistic magnetic reconnection are investigated by means of Relativistic Resistive Radiation Magnetohydrodynamic (R3MHD) simulations. We found that the radiation energy is confined within a narrow angle of outflow exhausts due to frequent interactions between the gas and radiation through the electron scattering process. The gas is dragged by radiation, leading to a slower outflow than that without radiation.

Takahashi, Hiroyuki R.; Ohsuga, Ken

2015-01-01

304

Computational Methods for Ideal Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Numerical schemes for the ideal magnetohydrodynamics (MHD) are widely used for modeling space weather and astrophysical flows. They are designed to resolve the different waves that propagate through a magnetohydro fluid, namely, the fast, Alfven, slow, and entropy waves. Numerical schemes for ideal magnetohydrodynamics that are based on the standard finite volume (FV) discretization exhibit pseudo-convergence in which non-regular waves no longer exist only after heavy grid refinement. A method is described for obtaining solutions for coplanar and near coplanar cases that consist of only regular waves, independent of grid refinement. The method, referred to as Compound Wave Modification (CWM), involves removing the flux associated with non-regular structures and can be used for simulations in two- and three-dimensions because it does not require explicitly tracking an Alfven wave. For a near coplanar case, and for grids with 213 points or less, we find root-mean-square-errors (RMSEs) that are as much as 6 times smaller. For the coplanar case, in which non-regular structures will exist at all levels of grid refinement for standard FV schemes, the RMSE is as much as 25 times smaller. A multidimensional ideal MHD code has been implemented for simulations on graphics processing units (GPUs). Performance measurements were conducted for both the NVIDIA GeForce GTX Titan and Intel Xeon E5645 processor. The GPU is shown to perform one to two orders of magnitude greater than the CPU when using a single core, and two to three times greater than when run in parallel with OpenMP. Performance comparisons are made for two methods of storing data on the GPU. The first approach stores data as an Array of Structures (AoS), e.g., a point coordinate array of size 3 x n is iterated over. The second approach stores data as a Structure of Arrays (SoA), e.g. three separate arrays of size n are iterated over simultaneously. For an AoS, coalescing does not occur, reducing memory efficiency. All results are given for Cartesian grids, but the algorithms are implemented for a general geometry on a unstructured grids.

Kercher, Andrew D.

305

Report on the MHD performance demonstration experiment, October 1, 1979-September 30, 1980  

SciTech Connect

The Arnold Engineering Development Center (AEDC) has been under contract with the Dept. of Energy (DOE) since December 1973 to modify existing equipment, install new hardware, and 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 the projected commercial MHD objectives are possible. The testing of the completed MHD system under power-producing conditions during the period from October 1, 1979, to September 30, 1980, is described. Initial experimental results have been obtained with the channel configured in the Faraday mode. The resistive loading was selected to give low supersonic velocities over the entire channel length. Tests have been conducted at magnetic fields up to 4.1 Telsa (T) (70 percent of design). Up to 23.5 MW of power has been produced to date (50 percent of design) for an enthalpy extraction of approximately 9 percent. Several electrical and hardware deterioration problems have developed during operation. High voltage electrical failures, such as arcs to ground at several locations at the high voltage end of the system and in the load circuit have occurred. Nozzle erosion and significant electrode cap ablation near the channel inlet have also been observed. Repair and improvement of these problems are underway. An analysis of the HPDE data has indicated the voltage drop is considerably in excess of those predictions used in the design of the HPDE channel. Voltage drops up to approximately 1500 v have been observed at a mean wall temperature of 700/sup 0/K. Extensive studies of electrode surface temperature distributions and alternate electrode cap materials have been undertaken.

Starr, R.F.; Christensen, L.S.; Whitehead, G.L.; Garrison, G.W.; Seiber, B.L.; Lowry, R.L.

1980-10-01

306

The Parabolic Jet Structure in M87 as a Magnetohydrodynamic Nozzle  

E-print Network

The structure and dynamics of the M87 jet from sub-milli-arcsec to arcsecond scales are continuously examined. We analysed the VLBA archival data taken at 43 and 86 GHz to measure the size of VLBI cores. Millimeter/sub-mm VLBI cores are considered as innermost jet emissions, which has been originally suggested by Blandford & K\\"onigl. Those components fairly follow an extrapolated parabolic streamline in our previous study so that the jet has a single power-law structure with nearly five orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 Schwarzschild radius ($r_{\\rm s}$). 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 Alfv\\'en waves. We examine the non-relativistic MHD nozzle equation in a parabolic shap...

Nakamura, Masanori

2013-01-01

307

MHD Turbulence and Magnetic Dynamos  

NASA Technical Reports Server (NTRS)

Incompressible magnetohydrodynamic (MHD) turbulence and magnetic dynamos, which occur in magnetofluids with large fluid and magnetic Reynolds numbers, will be discussed. When Reynolds numbers are large and energy decays slowly, the distribution of energy with respect to length scale becomes quasi-stationary and MHD turbulence can be described statistically. In the limit of infinite Reynolds numbers, viscosity and resistivity become zero and if these values are used in the MHD equations ab initio, a model system called ideal MHD turbulence results. This model system is typically confined in simple geometries with some form of homogeneous boundary conditions, allowing for velocity and magnetic field to be represented by orthogonal function expansions. One advantage to this is that the coefficients of the expansions form a set of nonlinearly interacting variables whose behavior can be described by equilibrium statistical mechanics, i.e., by a canonical ensemble theory based on the global invariants (energy, cross helicity and magnetic helicity) of ideal MHD turbulence. Another advantage is that truncated expansions provide a finite dynamical system whose time evolution can be numerically simulated to test the predictions of the associated statistical mechanics. If ensemble predictions are the same as time averages, then the system is said to be ergodic; if not, the system is nonergodic. Although it had been implicitly assumed in the early days of ideal MHD statistical theory development that these finite dynamical systems were ergodic, numerical simulations provided sufficient evidence that they were, in fact, nonergodic. Specifically, while canonical ensemble theory predicted that expansion coefficients would be (i) zero-mean random variables with (ii) energy that decreased with length scale, it was found that although (ii) was correct, (i) was not and the expected ergodicity was broken. The exact cause of this broken ergodicity was explained, after much investigation, by greatly extending the statistical theory of ideal MHD turbulence. The mathematical details of broken ergodicity, in fact, give a quantitative explanation of how coherent structure, dynamic alignment and force-free states appear in turbulent magnetofluids. The relevance of these ideal results to real MHD turbulence occurs because broken ergodicity is most manifest in the ideal case at the largest length scales and it is in these largest scales that a real magnetofluid has the least dissipation, i.e., most closely approaches the behavior of an ideal magnetofluid. Furthermore, the effects grow stronger when cross and magnetic helicities grow large with respect to energy, and this is exactly what occurs with time in a real magnetofluid, where it is called selective decay. The relevance of these results found in ideal MHD turbulence theory to the real world is that they provide at least a qualitative explanation of why confined turbulent magnetofluids, such as the liquid iron that fills the Earth's outer core, produce stationary, large-scale magnetic fields, i.e., the geomagnetic field. These results should also apply to other planets as well as to plasma confinement devices on Earth and in space, and the effects should be manifest if Reynolds numbers are high enough and there is enough time for stationarity to occur, at least approximately. In the presentation, details will be given for both theoretical and numerical results, and references will be provided.

Shebalin, John V

2014-01-01

308

MHD turbulence in the intracluster medium  

NASA Astrophysics Data System (ADS)

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.

Falceta-Gonçalves, Diego; Kowal, G.; de Gouveia Dal Pino, E.; Santos-Lima, R.; Nakwacki, S.; Lazarian, A.

2015-03-01

309

MHD integrated topping cycle project  

NASA Astrophysics Data System (ADS)

The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois no. 6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.

1992-01-01

310

MHD Integrated Topping Cycle Project  

SciTech Connect

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

Not Available

1992-01-01

311

A three-dimensional, iterative mapping procedure for the implementation of an ionosphere-magnetosphere anisotropic Ohm's law boundary condition in global magnetohydrodynamic simulations  

Microsoft Academic Search

The mathematical formulation of an iterative procedure for the numerical implementation of an ionosphere-magnetosphere (IM) anisotropic Ohm's law boundary condition is presented. The procedure may be used in global magnetohydrodynamic (MHD) simulations of the magnetosphere. The basic form of the boundary condition is well known, but a well-defined, simple, explicit method for implementing it in an MHD code has not

Michael L. Goodman

1995-01-01

312

Feasibility of MHD submarine propulsion  

SciTech Connect

This report describes the work performed during Phase 1 and Phase 2 of the collaborative research program established between Argonne National Laboratory (ANL) and Newport News Shipbuilding and Dry Dock Company (NNS). Phase I of the program focused on the development of computer models for Magnetohydrodynamic (MHD) propulsion. Phase 2 focused on the experimental validation of the thruster performance models and the identification, through testing, of any phenomena which may impact the attractiveness of this propulsion system for shipboard applications. The report discusses in detail the work performed in Phase 2 of the program. In Phase 2, a two Tesla test facility was designed, built, and operated. The facility test loop, its components, and their design are presented. The test matrix and its rationale are discussed. Representative experimental results of the test program are presented, and are compared to computer model predictions. In general, the results of the tests and their comparison with the predictions indicate that thephenomena affecting the performance of MHD seawater thrusters are well understood and can be accurately predicted with the developed thruster computer models.

Doss, E.D. (ed.) (Argonne National Lab., IL (United States)); Sikes, W.C. (ed.) (Newport News Shipbuilding and Dry Dock Co., VA (United States))

1992-09-01

313

Scale-up of advanced MHD generators  

NASA Astrophysics Data System (ADS)

The steady state performance and fluid mechanical behavior of linear, combustion-driven MHD power generators from laboratory-scale to commercial-scale are characterized through numerical analysis of seven real generator designs. Despite the diverse philosophies embodied in these designs, the power extraction parameters and quasi-three-dimensional fluid behavior correlate well with appropriate interaction parameters. The scale dependence of transverse conductivity nonuniformity and its influence on generator performance are examined, and the impact of the unconventional flow field in the MHD generator upon the design and performance of other MHD System components is discussed.

Maxwell, C. D.; Demetriades, S. T.; Oliver, D. A.; Vetter, A. A.; Swean, T. F.

1980-01-01

314

Experimental studies of explosively-driven magnetohydrodynamic generators. Final report, 1 October 1994--31 October 1997  

SciTech Connect

The field of High Power Microwaves (HPM) has evolved as a result of advances in the field of pulsed power, which has made pulses of electrical energy available that can drive HPM sources to gigawatt levels. One of the most compact forms of pulsed power involves the storage of chemical energy in the form of explosive charges. Explosive magnetohydrodynamic (MHD) generators are electrical power sources, which convert the kinetic energy of moving plasma into useful electrical energy through the magnetic portion of the Lorentz force. This report describes research conducted by the Air Force Research Laboratory to test specific designs of explosively driven magnetohydrodynamic generators. The goal of the research was to investigate the use of gigawatt generators in driving reactive loads appropriate to diode, and ultimately HPM applications. Two test series were performed, the first of which consisted of experiments on a low voltage generator and the second of which had the goal of scaling the existing design to higher voltage while retaining the reactive-type load. The complex problem of diagnostics of the plasma in this explosive test was addressed using fast, temporally resolved, plasma measurements, as well as spectroscopic plasma constituent measurements.

Agee, F.J.; Baca, G.; Chama, D.; Lehr, F.M.; Englert, T.

1997-10-01

315

Global invariants in ideal magnetohydrodynamic turbulence  

SciTech Connect

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.

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

316

Lattice Boltzmann formulation for Braginskii magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

We present a lattice Boltzmann formulation of the Braginskii magnetohydrodynamic equations that describe large-scale motions in strongly magnetised plasmas. Fluid quantities, density, velocity and stress, are represented by a finite set of distribution functions associated with particles moving on a square or cubic lattice. Equilibrium distributions are constructed from Hermite moment expansions, so slowly varying solutions of the discrete kinetic equation exactly satisfy the Navier--Stokes or MHD momentum equations. Electromagnetic quantities are represented by a second kinetic equation for a set of vector-valued distribution functions. Maxwell's equations and the resistive MHD induction equation may be recovered from slowly varying solutions using different scalings. The resulting algorithm, comprising only local operations at grid points and data copying between adjacent points, readily lends itself to large-scale parallel computations. We modify the collision operator to apply different relaxation times to components of the stress parallel and perpendicular to the local magnetic field, simulating a form of the Braginskii MHD equations encountered in astrophysics. Large shears develop in simulations where the fluid velocity perpendicular to the field lines reverses.

Dellar, Paul

2012-03-01

317

Propulsive efficiencies of magnetohydrodynamic submerged vehicular propulsors. Final report  

SciTech Connect

Magnetohydrodynamic (MHD) ship propulsion is the process of propelling a vehicular structure by a seawater electromagnetic pump. This propulsion system can be applied to a surface ship or a submerged vehicle; however, in this work only submerged vehicles at depths where wave effects can be neglected were considered. Although a number of different arrangements for a MHD propulsion system are possible, the general characteristics of such systems are most easily determined by a simple, ideal MHD rectangular duct of constant cross-sectional area. A mathematical model was developed for calculating the propulsive efficiencies of such a rectangular duct propelling a submerged vehicle. Numerical propulsive efficiencies are presented in terms of many different parameters. Assumptions were generally made in the model that tend to maximize the propulsive efficiency of the MHD system. Thus, the propulsive efficiencies calculated from the model overestimate the efficiencies of the corresponding real MHD propulsion system. These numerical results can be used for engineering estimates of the propulsive efficiencies of real MHD propulsion systems.

Brown, S.H.; Walker, J.S.; Sondergaard, N.A.; Reilly, P.J.; Bagley, D.E.

1990-04-01

318

FLASH magnetohydrodynamic simulations of shock-generated magnetic field experiments  

NASA Astrophysics Data System (ADS)

We report the results of benchmark FLASH magnetohydrodynamic (MHD) simulations of experiments conducted by the University of Oxford High Energy Density Laboratory Astrophysics group and its collaborators at the Laboratoire pour l'Utilisation des Lasers Intenses (LULI). In these experiments, a long-pulse laser illuminates a target in a chamber filled with Argon gas, producing shock waves that generate magnetic fields via the Biermann battery mechanism. We first outline the implementation of 2D cylindrical geometry in the unsplit MHD solver in FLASH and present results of verification tests. We then describe the results of benchmark 2D cylindrical MHD simulations of the LULI experiments using FLASH that explore the impact of external fields along with the possibility of magnetic field amplification by turbulence that is associated with the shock waves and that is induced by a grid placed in the gas-filled chamber.

Tzeferacos, P.; Fatenejad, M.; Flocke, N.; Gregori, G.; Lamb, D. Q.; Lee, D.; Meinecke, J.; Scopatz, A.; Weide, K.

2012-12-01

319

An Action Principle for Relativistic MHD  

E-print Network

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.

Eric D'Avignon; Philip Morrison; Francesco Pegoraro

2015-02-02

320

Jet Formation in GRBs: A Semi-analytic Model of MHD Flow in Kerr Geometry with Realistic Plasma Injection  

NASA Astrophysics Data System (ADS)

We construct a semi-analytic model for magnetohydrodynamic (MHD) flows in Kerr geometry that incorporates energy loading via neutrino annihilation on magnetic field lines threading the horizon. We compute the structure of the double-flow established in the magnetisphere for a wide range of energy injection rates and identify the different operation regimes. At low injection rates, the outflow is powered by the spinning black hole via the Blandford-Znajek mechanism, whereas at high injection rates, it is driven by the pressure of the plasma deposited on magnetic field lines. In the intermediate regime, both processes contribute to the outflow formation. The parameter that quantifies the load is the ratio of the net power injected below the stagnation radius and the maximum power that can be extracted magnetically from the black hole.

Globus, Noemie; Levinson, Amir

2014-11-01

321

ON THE ROLE OF INVOLUTIONS IN THE DISCONTINUOUS GALERKIN DISCRETIZATION OF MAXWELL AND MAGNETOHYDRODYNAMIC SYSTEMS  

NASA Technical Reports Server (NTRS)

The role of involutions in energy stability of the discontinuous Galerkin (DG) discretization of Maxwell and magnetohydrodynamic (MHD) systems is examined. Important differences are identified in the symmetrization of the Maxwell and MHD systems that impact the construction of energy stable discretizations using the DG method. Specifically, general sufficient conditions to be imposed on the DG numerical flux and approximation space are given so that energy stability is retained These sufficient conditions reveal the favorable energy consequence of imposing continuity in the normal component of the magnetic induction field at interelement boundaries for MHD discretizations. Counterintuitively, this condition is not required for stability of Maxwell discretizations using the discontinuous Galerkin method.

Barth, Timothy

2005-01-01

322

MHD shocks in coronal mass ejections  

NASA Technical Reports Server (NTRS)

The primary objective of this research program is the study of the magnetohydrodynamic (MHD) shocks and nonlinear simple waves produced as a result of the interaction of ejected lower coronal plasma with the ambient corona. The types of shocks and nonlinear simple waves produced for representative coronal conditions and disturbance velocities were determined. The wave system and the interactions between the ejecta and ambient corona were studied using both analytic theory and numerical solutions of the time-dependent, nonlinear MHD equations. Observations from the SMM coronagraph/polarimeter provided both guidance and motivation and are used extensively in evaluating the results. As a natural consequence of the comparisons with the data, the simulations assisted in better understanding the physical interactions in coronal mass ejections (CME's).

Steinolfson, R. S.

1991-01-01

323

The Generation and Damping of Propagating MHD Kink Waves in the Solar Atmosphere  

NASA Astrophysics Data System (ADS)

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.

Morton, R. J.; Verth, G.; Hillier, A.; Erdélyi, R.

2014-03-01

324

The superconducting MHD-propelled ship YAMATO-1  

SciTech Connect

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.

Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro

1995-04-01

325

The superconducting MHD-propelled ship YAMATO-1  

NASA Astrophysics Data System (ADS)

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.

Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro

1995-04-01

326

Using Faraday Rotation to Probe MHD Instabilities in Intracluster Media  

Microsoft Academic Search

It has recently been suggested that conduction-driven magnetohydrodynamic\\u000a(MHD) instabilities may operate at all radii within an intracluster medium\\u000a(ICM), and profoundly affect the structure of a cluster's magnetic field. Where\\u000aMHD instabilities dominate the dynamics of an ICM, they will re-orient magnetic\\u000afield lines perpendicular to the temperature gradient inside a cooling core, or\\u000aparallel to the temperature gradient

Tamara Bogdanovic; CHRISTOPHER S. REYNOLDS; Richard Massey

2010-01-01

327

The superconducting MHD-propelled ship YAMATO-1  

NASA Technical Reports Server (NTRS)

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.

Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro

1995-01-01

328

Large eddy simulation of decaying magnetohydrodynamic turbulence with dynamic subgrid-modeling  

Microsoft Academic Search

The numerical large eddy simulation (LES) technique is tested on decaying magnetohydrodynamic (MHD) turbulence. The LES approach allows for a strong reduction in computational cost compared to direct numerical simulations by modeling the effects of the smallest turbulent scales instead of computing them directly. Two small-scale models of eddy-viscosity type are presented for this purpose in combination with a procedure

O. Agullo; W.-C. Müller; B. Knaepen; D. Carati

2001-01-01

329

Series solution of a nonlinear ODE arising in magnetohydrodynamic by HPM-Padé technique  

Microsoft Academic Search

In this study, we investigate the magnetohydrodynamic (MHD) viscous flow due to a shrinking sheet by employing the homotopy perturbation method (HPM) and Padé approximation. The series solution of the governing nonlinear problem is developed. Generally, the truncated series solution is adequate only in a small region when the exact solution is not reached. We overcame this limitation by using

Behrouz Raftari; Ahmet Yildirim

2011-01-01

330

Magnetohydrodynamic simulation of the interaction between interplanetary strong shock and magnetic cloud and its consequent geoeffectiveness  

Microsoft Academic Search

Numerical studies have been performed to interpret the observed “shock overtaking magnetic cloud (MC)” event by a 2.5 dimensional magnetohydrodynamic (MHD) model in the heliospheric meridional plane. Results of an individual MC simulation show that the MC travels with a constant bulk flow speed. The MC is injected with a very strong inherent magnetic field over that in the ambient

Ming Xiong; Huinan Zheng; Yuming Wang; Shui Wang

2006-01-01

331

Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

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.

Xu, Kun

1998-01-01

332

Structure-function hierarchies and von Kármán-Howarth relations for turbulence in magnetohydrodynamical equations.  

PubMed

We generalize the method of A. M. Polyakov, [ Phys. Rev. E 52 6183 (1995)] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [ Eur. Phys. J. B 9 725 (1999)], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD. PMID:24580182

Basu, Abhik; Naji, Ali; Pandit, Rahul

2014-01-01

333

Radiation Magnetohydrodynamic Simulations of Protostellar Collapse: Nonideal Magnetohydrodynamic Effects and Early Formation of Circumstellar Disks  

NASA Astrophysics Data System (ADS)

The transport of angular momentum by magnetic fields is a crucial physical process in the formation and evolution of stars and disks. Because the ionization degree in star-forming clouds is extremely low, nonideal magnetohydrodynamic (MHD) effects such as ambipolar diffusion and ohmic dissipation work strongly during protostellar collapse. These effects have significant impacts in the early phase of star formation as they redistribute magnetic flux and suppress angular momentum transport by magnetic fields. We perform three-dimensional nested-grid radiation magnetohydrodynamic simulations including ohmic dissipation and ambipolar diffusion. Without these effects, magnetic fields transport angular momentum so efficiently that no rotationally supported disk is formed even after the second collapse. Ohmic dissipation works only in a relatively high density region within the first core and suppresses angular momentum transport, enabling formation of a very small rotationally supported disk after the second collapse. With both ohmic dissipation and ambipolar diffusion, these effects work effectively in almost the entire region within the first core and significant magnetic flux loss occurs. As a result, a rotationally supported disk is formed even before a protostellar core forms. The size of the disk is still small, about 5 AU at the end of the first core phase, but this disk will grow later as gas accretion continues. Thus, the nonideal MHD effects can resolve the so-called magnetic braking catastrophe while keeping the disk size small in the early phase, which is implied from recent interferometric observations.

Tomida, Kengo; Okuzumi, Satoshi; Machida, Masahiro N.

2015-03-01

334

Plasma rotation evolution near the peripheral transport barrier in the presence of low-frequency MHD bursts in TUMAN-3M tokamak  

Microsoft Academic Search

The experiments described in the paper are aimed at investigating the possible influence of the low frequency magnetohydrodynamic (MHD) activity burst on the Ohmic H-mode in the TUMAN-3M tokamak. During the MHD burst a transient deterioration of improved confinement was observed. The study has been focused on the measurements of plasma fluctuation poloidal velocity performed by microwave Doppler reflectometry. The

V. V. Bulanin; L. G. Askinazi; S. V. Lebedev; M. V. Gorohov; V. A. Kornev; A. V. Petrov; A. S. Tukachinsky; M. I. Vildjunas

2006-01-01

335

Locally Divergence-Free Discontinuous Galerkin Methods for MHD Equations  

Microsoft Academic Search

In this paper, we continue our investigation of the locally divergence-free discontinuous Galerkin method, originally developed for the linear Maxwell equations (J. Comput. Phys. 194 588–610 (2004)), to solve the nonlinear ideal magnetohydrodynamics (MHD) equations. The distinctive feature of such method is the use of approximate solutions that are exactly divergence-free inside each element for the magnetic field. As a

Fengyan Li; Chi-wang Shu

2005-01-01

336

Magneto-hydrodynamics Simulation in Astrophysics  

NASA Astrophysics Data System (ADS)

Magnetohydrodynamics (MHD) studies the dynamics of an electrically conducting fluid under the influence of a magnetic field. Many astrophysical phenomena are related to MHD, and computer simulations are used to model these dynamics. In this thesis, we conduct MHD simulations of non-radiative black hole accretion as well as fast magnetic reconnection. By performing large scale three dimensional parallel MHD simulations on supercomputers and using a deformed-mesh algorithm, we were able to conduct very high dynamical range simulations of black hole accretion of Sgr A* at the Galactic Center. We find a generic set of solutions, and make specific predictions for currently feasible observations of rotation measure (RM). The magnetized accretion flow is subsonic and lacks outward convection flux, making the accretion rate very small and having a density slope of around -1. There is no tendency for the flows to become rotationally supported, and the slow time variability of th! e RM is a key quantitative signature of this accretion flow. We also provide a constructive numerical example of fast magnetic reconnection in a three-dimensional periodic box. Reconnection is initiated by a strong, localized perturbation to the field lines and the solution is intrinsically three-dimensional. Approximately 30% of the magnetic energy is released in an event which lasts about one Alfvén time, but only after a delay during which the field lines evolve into a critical configuration. In the co-moving frame of the reconnection regions, reconnection occurs through an X-like point, analogous to the Petschek reconnection. The dynamics appear to be driven by global flows rather than local processes. In addition to issues pertaining to physics, we present results on the acceleration of MHD simulations using heterogeneous computing systems te{shan2006heterogeneous}. We have implemented the MHD code on a variety of heterogeneous and multi-core architectures (multi-core x86, Cell, Nvidia and ATI GPU) using different languages (FORTRAN, C, Cell, CUDA and OpenCL). Initial performance results for these systems are presented, and we conclude that substantial gains in performance over traditional systems are possible. In particular, it is possible to extract a greater percentage of peak theoretical performance from some heterogeneous systems when compared to x86 architectures.

Pang, Bijia

2011-08-01

337

Statistics of passive tracers in three-dimensional magnetohydrodynamic turbulence  

SciTech Connect

Magnetohydrodynamic (MHD) turbulence is studied from the Lagrangian viewpoint by following fluid particle tracers in high resolution direct numerical simulations. Results regarding turbulent diffusion and dispersion as well as Lagrangian structure functions are presented. Whereas turbulent single-particle diffusion exhibits essentially the same behavior in Navier-Stokes and MHD turbulence, two-particle relative dispersion in the MHD case differs significantly from the Navier-Stokes behavior. This observation is linked to the local anisotropy of MHD turbulence which is clearly reflected by quantities measured in a Lagrangian frame of reference. In the MHD case the Lagrangian structure functions display a lower level of intermittency as compared to the Navier-Stokes case contrasting Eulerian results. This is not only true for short time increments [H. Homann, R. Grauer, A. Busse, and W.-C. Mueller, J. Plasma Phys. 73, 821 (2007)] but also holds for increments up to the order of the integral time scale. The apparent discrepancy can be explained by the difference in the characteristic shapes of fluid particle trajectories in the vicinity of most singular dissipative structures.

Busse, Angela; Mueller, Wolf-Christian; Homann, Holger; Grauer, Rainer [Max-Planck-Institut fuer Plasmaphysik, 85748 Garching (Germany); Theoretische Physik I, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

2007-12-15

338

Energetic particles and magnetohydrodynamic activity in the Swarthmore Spheromak Experiment  

NASA Astrophysics Data System (ADS)

Results from the Swarthmore Spheromak Experiment (SSX) [M. R. Brown, Phys. Plasmas 6, 1717 (1999)] indicate that formation and partial merging of two spheromak plasmas can be described well by a magnetohydrodynamic (MHD) picture in which there is substantial evolution towards force free states within each vessel, while reconnection activity, also described reasonably well by MHD, occurs in the region of interaction. MHD simulations [V. S. Lukin et al., Phys. Plasmas 8, 1600 (2001)] support and provide further detail to this interpretation. In the present study, test particle equations are integrated using MHD data from SSX simulations to further understand the energetic particle fluxes that are observed experimentally. The test particle simulation is run with dimensionless parameters similar to the experiment, and particles are permitted to escape when they encounter the simulated SSX boundaries. MHD activity related to reconnection is responsible for accelerating charged particles. The process includes two phases—a strong but short duration direct acceleration in the quasi-steady reconnection electric field, and a weaker longer lived stochastic component associated with turbulence.

Qin, G.; Lukin, V. S.; Cothran, C. D.; Brown, M. R.; Matthaeus, W. H.

2001-11-01

339

Shock formation in magnetohydrodynamical accretion onto a black hole  

NASA Astrophysics Data System (ADS)

Magnetohydrodynamic (MHD) accretion onto a black hole is studied. The general relativistic MHD accretion was calculated by a numerical method. By using the new method of calculation, the angular momentum of the fluid generated by the black hole which is placed in the static medium with the uniform density and the uniform magnetic field is studied. The interaction between the magnetic field and the fluid matter in the rotating space time enhances the energy for the fluid and reduces the energy for the magnetic field. The rapidly rotating black hole produces the negative energy region in the distribution of the energy density for the magnetic field. The magnetic field transports the energy and the angular momentum from the stretched horizon to the outer atmosphere. The asymmetry of the flow increases the critical Mach number: MAC much greater than one. The MHD accretion with an initially uniform magnetic field produces the peaks of the magnetic stress near the event horizon. The perturbations at the peaks grow at MAC = 30. The gas energy density perturbs the MHD flow and generates the shock waves. The shock waves generated near the horizon may produce the large amount of X ray emission. The emission mechanism of the X ray radiation from the black hole candidates is discussed with the MHD accretion model.

Yokosawa, Masayoshi

1993-05-01

340

A Meshless Method for Magnetohydrodynamics and Applications to Protoplanetary Disks  

NASA Astrophysics Data System (ADS)

This thesis presents an algorithm for simulating the equations of ideal magnetohydrodynamics and other systems of differential equations on an unstructured set of points represented by sample particles. Local, third-order, least-squares, polynomial interpolations (Moving Least Squares interpolations) are calculated from the field values of neighboring particles to obtain field values and spatial derivatives at the particle position. Field values and particle positions are advanced in time with a second order predictor-corrector scheme. The particles move with the fluid, so the time step is not limited by the Eulerian Courant-Friedrichs-Lewy condition. Full spatial adaptivity is implemented to ensure the particles fill the computational volume, which gives the algorithm substantial flexibility and power. A target resolution is specified for each point in space, with particles being added and deleted as needed to meet this target. Particle addition and deletion is based on a local void and clump detection algorithm. Dynamic artificial viscosity fields provide stability to the integration. The resulting algorithm provides a robust solution for modeling flows that require Lagrangian or adaptive discretizations to resolve. The code has been parallelized by adapting the framework provided by Gadget-2. A set of standard test problems, including one part in a million amplitude linear MHD waves, magnetized shock tubes, and Kelvin-Helmholtz instabilities are presented. Finally we demonstrate good agreement with analytic predictions of linear growth rates for magnetorotational instability in a cylindrical geometry. We provide a rigorous methodology for verifying a numerical method on two dimensional Kelvin-Helmholtz instability. The test problem was run in the Pencil Code, Athena, Enzo, NDSPHMHD, and Phurbas. A strict comparison, judgment, or ranking, between codes is beyond the scope of this work, although this work provides the mathematical framewor! k needed for such a study. Nonetheless, how the test is posed circumvents the issues raised by tests starting from a sharp contact discontinuity yet it still shows the poor performance of Smoothed Particle Hydrodynamics. We then comment on the connection between this behavior and the underlying lack of zeroth-order consistency in Smoothed Particle Hydrodynamics interpolation. In astrophysical magnetohydrodynamics (MHD) and electrodynamics simulations, numerically enforcing the divergence free constraint on the magnetic field has been difficult. We observe that for point-based discretization, as used in finite-difference type and pseudo-spectral methods, the divergence free constraint can be satisfied entirely by a choice of interpolation used to define the derivatives of the magnetic field. As an example we demonstrate a new class of finite-difference type derivative operators on a regular grid which has the divergence free property. This principle clarifies the nature of magnetic monopole errors. The principles and techniques demonstrated in this chapter are particularly useful for the magnetic field, but can be applied to any vector field. Finally, we examine global zoom-in simulations of turbulent magnetorotationally unstable flow. We extract and analyze the high-current regions produced in the turbulent flow. Basic parameters of these regions are abstracted, and we build one dimensional models including non-ideal MHD, and radiative transfer. For sufficiently high temperatures, an instability resulting from the temperature dependence of the Ohmic resistivity is found. This instability concentrates current sheets, resulting in the possibility of rapid heating from temperatures on the order of 600 Kelvin to 2000 Kelvin in magnetorotationally turbulent regions of protoplanetary disks. This is a possible local mechanism for the melting of chondrules and the formation of other high-temperature materials in protoplanetary disks.

McNally, Colin P.

2012-08-01

341

MHD Contractors' Review Meeting: Abstracts  

NASA Astrophysics Data System (ADS)

The objectives of the Integrated Topping Cycle project are to design, construct, and deliver all prototypical hardware necessary to conduct long duration integrated MHD topping cycle proof-of-concept tests at the Component Development and Integration Facility (CDIF) in Butte, Montana. The results of the long duration tests will augment the existing engineering data base on MHD power train reliability, maintainability, durability, and performance, and will serve as a basis for scaling up to the early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include the following three systems: (1) a slagging coal combustion subsystem with a rated capacity of 50 MW thermal input, capable of operation with eastern (Illinois) or western (Montana Rosebud) coal; (2) a channel subsystem consisting of a segmented supersonic nozzle, channel (with current controls), and diffuser, capable of power output of 1.5 MW(sub e); and (3) a current consolidation subsystem to interface the channel with the existing facility inverter.

342

Magnetized Accretion-Ejection Structures: 2.5-dimensional Magnetohydrodynamic Simulations of Continuous Ideal Jet Launching from Resistive Accretion Disks  

Microsoft Academic Search

We present numerical magnetohydrodynamic (MHD) simulations of a magnetized accretion disk launching trans-Alfvénic jets. These simulations, performed in a 2.5-dimensional time-dependent polytropic resistive MHD framework, model a resistive accretion disk threaded by an initial vertical magnetic field. The resistivity is only important inside the disk and is prescribed as eta=alphamVAHexp(- 2Z2\\/H2), where VA stands for Alfvén speed, H is the

Fabien Casse; Rony Keppens

2002-01-01

343

MHD high performance demonstration experiment  

NASA Astrophysics Data System (ADS)

The attainment of MHD performance on a sufficiently large scale to verify that the projected efficiency of the commercial MHD concept is considered. Shakedown testing of the magnet and flow train was completed and operation of the HPDE system in the Faraday power producing mode has continued. A peak power of about 18 MW was produced with a magnetic field of 2.8 T. Significant results which were obtained involved a definition of the transverse voltage characteristics, including the voltage drop near the electrode walls, and a definition of the fluid flow through the channel and diffuser. Several operational problems were encountered including erosion of heat sink components of the burner and channel entrance and Hall potential shorting at the aft end of the channel and diffuser. Required hardware procurement and modification were initiated by the end of the quarter to solve these problems.

1980-01-01

344

High Resolution Simulations of Relativistic Hydrodynamic and MHD Turbulence  

NASA Astrophysics Data System (ADS)

We present a program of simulations designed to investigate the basic properties of relativistic hydrodynamic and magnetohydrodynamic (MHD) turbulence. We employ a well-tested 5th-order accurate numerical scheme at resolutions of up to 2048^3 zones for hydrodynamic turbulence, and a minimally diffusive 2nd-order scheme at resolutions of up to 1024^3 in the case of relativistic MHD. For the hydrodynamic case, we simulate a relativistically hot gas in a cubic periodic domain continuously driven at large scales with Lorentz factor of about 3. We find that relativistic turbulent velocity fluctuations with ? ? > 1 persist from the driving scale down to scales an order of magnitude smaller, demonstrating the existence of a sustained relativistic turbulent cascade. The power spectrum of the fluid 4-velocity is broadly Kolmogorov-like, roughly obeying a power law with 5/3 index between scales 1/10 and 1/100 of the domain. Departures from 5/3 scaling are larger for the power spectrum of 3-velocity. We find that throughout the inertial interval, 25% of power is in dilatational modes, which obey strict power law scaling between 1/2 and 1/100 of the domain with an index of 1.88. Our program also explores turbulent amplification of magnetic fields in the conditions of merging neutron stars, using a realistic equation of state for dense nuclear matter (? ˜ 10^13 g/cm^3). We find that very robustly, seed fields are amplified to magnetar strength (? 4 * 10^16 Gauss) within ˜1 micro-second for fluid volumes near the size of the NS crust thickness <10 meters. We present power spectra of the kinetic and magnetic energy taken long into the fully stationary evolution of the highest resolution models, finding the magnetic energy to be in super-equipartition (4 times larger) with the kinetic energy through the inertial range. We believe that current global simulations of merging NS binaries are insufficiently resolved for studying field amplification via turbulent processes. Larger magnetic fields, as found in our high resolution local simulations, may have consequences for gravitational wave signals, GRB precursor events, radio afterglows, and optical afterglows due to emission from ejected radioactive r-process material.

Zrake, Jonathan; MacFadyen, A.

2013-01-01

345

Electron magnetohydrodynamics: Dynamics and turbulence  

NASA Astrophysics Data System (ADS)

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.

Lyutikov, Maxim

2013-11-01

346

Large amplitude MHD waves upstream of the Jovian bow shock  

NASA Technical Reports Server (NTRS)

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.

Goldstein, M. L.; Smith, C. W.; Matthaeus, W. H.

1983-01-01

347

Optimum performance of MHD-augumented chemical rocket thrusters for space propulsion applications  

SciTech Connect

The use of magnetohydrodynamic (MHD) acceleration of a chemical rocket exhaust stream, to augment the thrust of small, space-propulsion type chemical thrusters was examined, with the purpose of identifying {open_quotes}optimum{close_quotes} performance. Optimum performance is defined herein as the highest spacecraft acceleration levels with concurrent highest specific impulse, that the hybrid propulsion system can generate, given a fixed mass flow of propellant and fixed chamber pressure (150 psia). The exhaust nozzle-MHD channel selected was of the simplest kind, a three-segmented Faraday generator, for simplicity in design, manufacture, and power control circuit assembly. The channel expanded in only one plane or direction, the plane intersecting the electrodes. The distance between the side walls was fixed. Three different fuel oxidizer combinations were investigated: H{sub 2} - O{sub 2}, fuel oil - O{sub 2}, and hydrazine - nitrogen tetroxide. These represent the spectrum of typical liquid rocket propellants. The fraction of the propellant flow representing potassium, as K{sub 2}CO{sub 3}, was kept constant at 1/2 percent of the total propellant flow. The results of the study verify that the MHD-augmented chemical thruster will be an important propulsion system option for space missions requiring accelerations of the order of milli-gravities with specific impulses of the order of 4,000 seconds. The system study showed that a 3-segmented, diverging Faraday channel with about a 2{degrees} divergence angle, enclosed by a 4 Tesla magnet, was capable of providing exhaust gas exit velocities of the order of 40000 m/s for all three propellant combinations. Hence, a hybrid propulsion system of the type identified here is capable of providing thrusts of the order of 400 Newtons, spacecraft accelerations of the order 2 milli-gravities, with electric power requirements of about 2.4 megawatts, based on propellant total mass flow rates of about 10 grams per second.

Schulz, R.J.; Chapman, J.N. [Univ. of Tennessee Space Institute, Tullahoma, TN (United States)

1995-12-31

348

BOOK REVIEW: Nonlinear Magnetohydrodynamics  

Microsoft Academic Search

Nonlinear magnetohydrodynamics by Dieter Biskamp is a thorough introduction to the physics of the most impressive non-linear phenomena that occur in conducting magnetoplasmas. The basic systems, in which non-trivial dynamic processes are observed, accompanied by changes of geometry of the magnetic field and the effects of energy transformation (magnetic energy into kinetic energy or the opposite effect in magnetic dynamos),

D. Biskamp

1998-01-01

349

US/USSR cooperative program in open-cycle MHD electrical power generation: joint test report No. 4. Tests in the U-25B facility: MHD generator tests No. 6 and 7  

SciTech Connect

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.

Picologlou, B F; Batenin, V M

1981-01-01

350

Outline of fast analyzer for MHD equilibrium FAME  

NASA Astrophysics Data System (ADS)

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.

Sakata, Shinya; Haginoya, Hirofumi; Tsuruoka, Takuya; Aoyagi, Tetsuo; Saito, Naoyuki; Harada, Hiroo; Tani, Keiji; Watanabe, Hideto

1994-02-01

351

Using Faraday Rotation to Probe MHD Instabilities in Intracluster Media  

E-print Network

It has recently been suggested that conduction-driven magnetohydrodynamic (MHD) instabilities may operate at all radii within an intracluster medium (ICM), and profoundly affect the structure of a cluster's magnetic field. Where MHD instabilities dominate the dynamics of an ICM, they will re-orient magnetic field lines perpendicular to the temperature gradient inside a cooling core, or parallel to the temperature gradient outside it. This characteristic structure of magnetic field could be probed by measurements of polarized radio emission from background sources. Motivated by this possibility we have constructed 3-d models of a magnetized cooling core cluster and calculated Faraday rotation measure (RM) maps in the plane of the sky under realistic observing conditions. We compare a scenario in which magnetic field geometry is characterized by conduction driven MHD instabilities to that where it is determined by the turbulent motions. We find that future high-sensitivity spectro-polarimetric measurements of R...

Bogdanovic, Tamara; Massey, Richard

2010-01-01

352

An ADI-based adaptive mesh Poisson solver for the MHD code NIRVANA  

Microsoft Academic Search

I describe a Poisson solver for the adaptive mesh magnetohydrodynamics (MHD) code NIRVANA using ADI techniques (ADI: Alternative Direction Implicit). The solver is fit to the mesh refinement framework of the code and utilizes its special block-structured design. The key part of the method is an algorithm for the intelligent clustering of subgrids which permits the application of numerical methods

Udo Ziegler

2004-01-01

353

Flow control of seawater with a diverging duct by MHD separation method  

Microsoft Academic Search

A unique control method for a diverging seawater flow based on electromagnetic force, the so-called MHD (magnetohydrodynamics) separation method, is performed. The experimental apparatus is composed of a 10-T class superconducting magnet, a separation cell, a seawater tank, and a flow system. The constructed separation cell contains parallel electrodes, 18 mm wide, 40 mm long and 20 mm apart, and

Minoru Takeda; Naotaka Tomomori; Teruhiko Akazawa; Kazu Nishigaki; Akira Iwata

2004-01-01

354

Application of homotopy perturbation method to the MHD pipe flow of a fourth grade fluid  

Microsoft Academic Search

This paper applies He's homotopy perturbation method (HPM) to analyze the strongly nonlinear magneto-hydrodynamic (MHD) flow of a fourth grade fluid through a circular pipe. In this method, a homotopy is constructed for the equation. The initial approximations can be freely chosen with possible unknown constants which can be determined by imposing the boundary and initial conditions. The results reveal

A. Ranjbar Noiey; N. Haghparast; M. Miansari; D. D. Ganji

2008-01-01

355

Slip effects on MHD flow of a generalized Oldroyd-B fluid with fractional derivative  

Microsoft Academic Search

This paper presents an analysis for magnetohydrodynamic (MHD) flow of an incompressible generalized Oldroyd-B fluid inducing by an accelerating plate. Where the no-slip assumption between the wall and the fluid is no longer valid. The fractional calculus approach is introduced to establish the constitutive relationship of a viscoelastic fluid. Closed form solutions for velocity and shear stress are obtained in

Liancun Zheng; Yaqing Liu; Xinxin Zhang

356

MHD Flow of an Oldroyd-B Fluid through a Porous Space Induced by Sawtooth Pulses  

Microsoft Academic Search

We investigate the unsteady magnetohydrodynamic (MHD) flow of an Oldroyd-B fluid through a porous space induced by sawtooth pulses. The fluid is assumed to be electrically conducting in the presence of a transverse uniform magnetic field. The porous space is taken into account using modified Darcy's law for the Oldroyd-B fluid. Exact solutions of the governing problem are obtained by

Khan Masood; Zeeshan

2011-01-01

357

MHD Flow of an Oldroyd-B fluid between eccentric rotating disks  

Microsoft Academic Search

An exact solution is obtained for the magnetohydrodynamics (MHD) flow of a conducting, incompressible Oldroyd-B fluid between two infinite, parallel, insulated disks rotating about non-coincident axes normal to the disks in the presence of a uniform transverse magnetic field. The effects of the Hartmann number M, the Deborah number D, the Reynolds number R and the elastic number ? on

H. Volkan Ersoy

1999-01-01

358

Unsteady MHD Couette flow of a generalized Oldroyd-B fluid with fractional derivative  

Microsoft Academic Search

This paper presents an analytical study for the magnetohydrodynamic (MHD) flow of a generalized Oldroyd-B fluid. The fractional calculus approach is used to establish the constitutive relationship model of a viscoelastic fluid. Exact analytic solutions for the velocity field and shear stress in terms of Fox H-function are obtained by means of the Laplace transform. The influence of the relaxation

Yaqing Liu; Liancun Zheng; Xinxin Zhang

2011-01-01

359

A numerical algorithm for MHD of free surface flows at low magnetic Reynolds numbers  

Microsoft Academic Search

We have developed a numerical algorithm and computational software for the study of magnetohydrodynamics (MHD) of free surface flows at low magnetic Reynolds numbers. The governing system of equations is a coupled hyperbolic–elliptic system in moving and geometrically complex domains. The numerical algorithm employs the method of front tracking and the Riemann problem for material interfaces, second order Godunov-type hyperbolic

Roman Samulyak; Jian Du; James Glimm; Zhiliang Xu

2007-01-01

360

Multiple time scale methods in tokamak magnetohydrodynamics  

SciTech Connect

Several methods are discussed for integrating the magnetohydrodynamic (MHD) equations in tokamak systems on other than the fastest time scale. The dynamical grid method for simulating ideal MHD instabilities utilizes a natural nonorthogonal time-dependent coordinate transformation based on the magnetic field lines. The coordinate transformation is chosen to be free of the fast time scale motion itself, and to yield a relatively simple scalar equation for the total pressure, P = p + B/sup 2//2..mu../sub 0/, which can be integrated implicitly to average over the fast time scale oscillations. Two methods are described for the resistive time scale. The zero-mass method uses a reduced set of two-fluid transport equations obtained by expanding in the inverse magnetic Reynolds number, and in the small ratio of perpendicular to parallel mobilities and thermal conductivities. The momentum equation becomes a constraint equation that forces the pressure and magnetic fields and currents to remain in force balance equilibrium as they evolve. The large mass method artificially scales up the ion mass and viscosity, thereby reducing the severe time scale disparity between wavelike and diffusionlike phenomena, but not changing the resistive time scale behavior. Other methods addressing the intermediate time scales are discussed.

Jardin, S.C.

1984-01-01

361

Magneto-hydrodynamically stable axisymmetric mirrors  

SciTech Connect

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.

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

362

Large-Scale Quasi-geostrophic Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

We consider the ideal magnetohydrodynamics (MHD) of a shallow fluid layer on a rapidly rotating planet or star. The presence of a background toroidal magnetic field is assumed, and the "shallow water" beta-plane approximation is used. We derive a single equation for the slow large length scale dynamics. The range of validity of this equation fits the MHD of the lighter fluid at the top of Earth's outer core. The form of this equation is similar to the quasi-geostrophic (Q-G) equation (for usual ocean or atmosphere), but the parameters are essentially different. Our equation also implies the inverse cascade; but contrary to the usual Q-G situation, the energy cascades to smaller length scales, while the enstrophy cascades to the larger scales. We find the Kolmogorov-type spectrum for the inverse cascade. The spectrum indicates the energy accumulation in larger scales. In addition to the energy and enstrophy, the obtained equation possesses an extra (adiabatic-type) invariant. Its presence implies energy accumulation in the 30° sector around zonal direction. With some special energy input, the extra invariant can lead to the accumulation of energy in zonal magnetic field; this happens if the input of the extra invariant is small, while the energy input is considerable.

Balk, Alexander M.

2014-12-01

363

Modeling eruptive coronal magnetohydrodynamic systems with FLUX  

NASA Astrophysics Data System (ADS)

In this dissertation I explore solar coronal energetic eruptions in the context of magnetic reconnection, which is commonly thought to be a required trigger mechanism for solar eruptions. Reconnection is difficult to directly observe in the corona, and current numerical methods cannot model reconnectionless control cases. Thus, it is not possible to determine if reconnection is a necessary component of these eruptions. I have executed multiple controlled simulations to determine the importance of reconnection for initiation and evolution of several eruptive systems using FLUX, a numerical model that uses the comparatively new fluxon technique. I describe two types of eruptions modeled with FLUX: a metastable confined flux rope theory for coronal mass ejection (CME) initiation, and symmetrically twisted coronal jets in a uniform vertical background field. In the former, I identified an ideal magnetohydrodynamic (MHD) instability that allows metastable twisted flux rope systems to suddenly lose stability and erupt even in the absence of reconnection, contradicting previous conjecture. The CME result is in contrast to the azimuthally symmetric coronal jet initiation model, where jet-like behavior does not manifest without reconnection. My work has demonstrated that some of the observed eruptive phenomena may be triggered by non-reconnective means such as ideal MHD instabilities, and that magnetic reconnection is not a required element in all coronal eruptions.

Rachmeler, L. A.

364

MHD contractors' review conference  

NASA Astrophysics Data System (ADS)

The MHD Contractors' Review Conference was held at Pittsburgh, PA, February 2-4, 1993. Eleven papers were presented. Papers were related to the CDIF topping cycle, to the CFFF bottoming cycle, diagnostic techniques, heat recovery, seed recovery, design of a coal-fired MHD retrofit plant, and the design of a retrofit MHD magnet. Papers have not been entered individually in view of the rather narrow subject area.

365

The magnetohydrodynamics coal-fired flow facility  

NASA Astrophysics Data System (ADS)

In this quarterly technical progress report, UTSI reports on the status of a multitask contract to develop the technology for the steam bottoming portion of a MHD Steam Combined Cycle Power Plant. The report describes the facility maintenance and environmental work completed, status of completing technical reports and certain key administrative actions occurring during the quarter. With program resources at a minimum to closeout the MHD program, no further testing occurred during the quarter, but the DOE CFFF facility was maintained in a standby status with winterization, preventive maintenance and repairs accomplished as needed. Plans and preparations progressed for environmental actions needed at the site to investigate and characterize the groundwater and for removal/disposal of asbestos in the cooling tower. Work continued to progress on archiving the results of the MHD program.

1995-01-01

366

Status of Magnetohydrodynamic Augmented Propulsion Experiment  

NASA Technical Reports Server (NTRS)

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

Litchford, Ron J.; Lineberry, John T.

2007-01-01

367

MHD Coal-Fired Flow Facility. Quarterly/annual technical progress report, October-December 1979  

SciTech Connect

In this Fourth Quarterly/Annual Report submitted under DOE contracts EX-76-C-01-1760 and DE-AC02-79ET10815, the University of Tennessee Space Institute (UTSI) reports on significant activity, task status, planned research, testing, and development, and conclusions for the Magnetohydrodynamics (MHD) Coal-Fired Flow Facility (CFFF) and the Research and Development Laboratory. Work on the CFFF progressed with only minor problems. Total construction activity for all site work presently awarded is nearly 98% complete. Water analysis shows that Woods Reservoir baseline conditions are within EPA or Tennessee drinking water standards. For the primary combustor, the vitiation heater and primary combustor fabrication drawings were completed and the nozzle design was completed. The drum module for the radiant slagging furnace was awarded. On the MHD Power Generator, development continued in several areas of advanced analysis including development of time-dependent models for use with the one-dimensional code. For seed regeneration, the tentative determination is that the Tomlinson Tampella is the most economically viable method. With regard to capped electrode erosion, investigations have shown that the major degradation of the cladding still present is at the leading edge of the capped anode. To alleviate this, plans are to hot work the noble metal in the bending operation. In resolving another problem, a system employing the modified line-reversal method has been assembled and successfully tested to measure absolute plasma temperatures.

Dicks, J. B.; Chapman, J. N.; Crawford, L. W.

1980-02-01

368

Numerical Simulation of Turbulent MHD Flows Using an Iterative PNS Algorithm  

NASA Technical Reports Server (NTRS)

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.

Kato, Hiromasa; Tannehill, John C.; Mehta, Unmeel B.

2003-01-01

369

Characteristics of Faraday and diagonal MHD generators with cryogenic magnet systems  

SciTech Connect

This paper addresses linear magnetohydrodynamic (MHD) generators of the Faraday and diagonal types with cryogenic saddle-shaped magnet systems. Procedures are described for the calculation of the characteristics of MHD generator on the basis of quasi-one-dimensional analysis of MHD processes in the generator channel with due regard for the dynamics of development of the boundary layer on the channel wall and for the two-dimensional calculation of the stressed-strained state of the winding and structural elements of the magnet system in the approximation of the theory of composite shells. The choice and partial optimization of the parameters of MHD channel and magnet system involve the use of methods of nonlinear programming. The results are given of the calculation of the outlet parameters, mass and dimensions of MHD generators of the Faraday and diagonal types with cryoconducting magnet system.

Kovalev, L.K.; Koneev, S.M.A.; Larionov, A.E. [Moscow Institute of Aviation (Russian Federation)

1995-03-01

370

Validation of Magnetospheric Magnetohydrodynamic Models  

NASA Astrophysics Data System (ADS)

Magnetospheric magnetohydrodynamic (MHD) models are commonly used for both prediction and modeling of Earth's magnetosphere. To date, very little validation has been performed to determine their limits, uncertainties, and differences. In this work, we performed a comprehensive analysis using several commonly used validation techniques in the atmospheric sciences to MHD-based models of Earth's magnetosphere for the first time. The validation techniques of parameter variability/sensitivity analysis and comparison to other models were used on the OpenGGCM, BATS-R-US, and SWMF magnetospheric MHD models to answer several questions about how these models compare. The questions include: (1) the difference between the model's predictions prior to and following to a reversal of Bz in the upstream interplanetary field (IMF) from positive to negative, (2) the influence of the preconditioning duration, and (3) the differences between models under extreme solar wind conditions. A differencing visualization tool was developed and used to address these three questions. We find: (1) For a reversal in IMF Bz from positive to negative, the OpenGGCM magnetopause is closest to Earth as it has the weakest magnetic pressure near-Earth. The differences in magnetopause positions between BATS-R-US and SWMF are explained by the influence of the ring current, which is included in SWMF. Densities are highest for SWMF and lowest for OpenGGCM. The OpenGGCM tail currents differ significantly from BATS-R-US and SWMF; (2) A longer preconditioning time allowed the magnetosphere to relax more, giving different positions for the magnetopause with all three models before the IMF Bz reversal. There were differences greater than 100% for all three models before the IMF Bz reversal. The differences in the current sheet region for the OpenGGCM were small after the IMF Bz reversal. The BATS-R-US and SWMF differences decreased after the IMF Bz reversal to near zero; (3) For extreme conditions in the solar wind, the OpenGGCM has a large region of Earthward flow velocity (Ux) in the current sheet region that grows as time progresses in a compressed environment. BATS-R-US Bz , rho and Ux stabilize to a near constant value approximately one hour into the run under high compression conditions. Under high compression, the SWMF parameters begin to oscillate approximately 100 minutes into the run. All three models have similar magnetopause positions under low pressure conditions. The OpenGGCM current sheet velocities along the Sun-Earth line are largest under low pressure conditions. The results of this analysis indicate the need for accounting for model uncertainties and differences when comparing model predictions with data, provide error bars on model prediction in various magnetospheric regions, and show that the magnetotail is sensitive to the preconditioning time.

Curtis, Brian

371

Nonlinear Dynamics of Magnetohydrodynamic Rossby Waves and the Cyclic Nature of Solar Magnetic Activity  

NASA Astrophysics Data System (ADS)

The solar dynamo is known to be associated with several periodicities, with the nearly 11/22 yr cycle being the most pronounced one. Even though these quasiperiodic variations of solar activity have been attributed to the underlying dynamo action in the Sun's interior, a fundamental theoretical description of these cycles is still elusive. Here, we present a new possible direction in understanding the Sun's cycles based on resonant nonlinear interactions among magnetohydrodynamic (MHD) Rossby waves. The WKB theory for dispersive waves is applied to magnetohydrodynamic shallow-water equations describing the dynamics of the solar tachocline, and the reduced dynamics of a resonant triad composed of MHD Rossby waves embedded in constant toroidal magnetic field is analyzed. In the conservative case, the wave amplitudes evolve periodically in time, with periods on the order of the dominant solar activity timescale (~11 yr). In addition, the presence of linear forcings representative of either convection or instabilities of meridionally varying background states appears to be crucial in balancing dissipation and thus sustaining the periodic oscillations of wave amplitudes associated with resonant triad interactions. Examination of the linear theory of MHD Rossby waves embedded in a latitudinally varying mean flow demonstrates that MHD Rossby waves propagate toward the equator in a waveguide from -35° to 35° in latitude, showing a remarkable resemblance to the structure of the butterfly diagram of the solar activity. Therefore, we argue that resonant nonlinear magnetohydrodynamic Rossby wave interactions might significantly contribute to the observed cycles of magnetic solar activity.

Raphaldini, Breno; Raupp, Carlos F. M.

2015-01-01

372

Magnetohydrodynamic sea water propulsion  

Microsoft Academic Search

An experimental and theoretical investigation of a large scale MHD propulsor has been undertaken whose objectives are to (1) investigate the transient and steady state performance of the thruster over operating parameter ranges that are compatible with achievement of high efficiency, (2) to quantify the principal loss mechanisms within the thruster and (3) to obtain preliminary hydroacoustic data. The performance

M. Petrick; A. Thomas; L. Genens; J. Libera; R. Nietert; J. Bouillard; E. Pierson; D. Hill; B. Picologlou; O. Ohlsson; T. Kasprzyk; G. Berry

1991-01-01

373

Scale interactions in magnetohydrodynamic turbulence  

E-print Network

This article reviews recent studies of scale interactions in magnetohydrodynamic turbulence. The present day increase of computing power, which allows for the exploration of different configurations of turbulence in conducting flows, and the development of shell-to-shell transfer functions, has led to detailed studies of interactions between the velocity and the magnetic field and between scales. In particular, processes such as induction and dynamo action, the damping of velocity fluctuations by the Lorentz force, or the development of anisotropies, can be characterized at different scales. In this context we consider three different configurations often studied in the literature: mechanically forced turbulence, freely decaying turbulence, and turbulence in the presence of a uniform magnetic field. Each configuration is of interest for different geophysical and astrophysical applications. Local and non-local transfers are discussed for each case. While the transfer between scales of solely kinetic or solely ...

Mininni, P D

2010-01-01

374

Statistical Analysis of Current Sheets in Three-dimensional Magnetohydrodynamic Turbulence  

NASA Astrophysics Data System (ADS)

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.

Zhdankin, Vladimir; Uzdensky, Dmitri A.; Perez, Jean C.; Boldyrev, Stanislav

2013-07-01

375

STATISTICAL ANALYSIS OF CURRENT SHEETS IN THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC TURBULENCE  

SciTech Connect

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.

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

376

Approximate Riemann solver for magnetohydrodynamics (that works in more than one dimension)  

NASA Astrophysics Data System (ADS)

An approximate Riemann solver is developed for the governing equations of ideal magnetohydrodynamics (MHD). The Riemann solver has an eight-wave structure, where seven of the waves are those used in previous work on upwind schemes for MHD, and the eighth wave is related to the divergence of the magnetic field. The structure of the eighth wave is not immediately obvious from the governing equations as they are usually written, but arises from a modification of the equations that is presented in this paper. The addition of the eighth wave allows multi-dimensional MHD problems to be solved without the use of staggered grids or a projection scheme, one or the other of which was necessary in previous work on upwind schemes for MHD. A test problem made up of a shock tube with rotated initial conditions is solved to show that the two-dimensional code yields answers consistent with the one-dimensional methods developed previously.

Powell, K. G.

1994-03-01

377

An approximate Riemann solver for magnetohydrodynamics (that works in more than one dimension)  

NASA Technical Reports Server (NTRS)

An approximate Riemann solver is developed for the governing equations of ideal magnetohydrodynamics (MHD). The Riemann solver has an eight-wave structure, where seven of the waves are those used in previous work on upwind schemes for MHD, and the eighth wave is related to the divergence of the magnetic field. The structure of the eighth wave is not immediately obvious from the governing equations as they are usually written, but arises from a modification of the equations that is presented in this paper. The addition of the eighth wave allows multidimensional MHD problems to be solved without the use of staggered grids or a projection scheme, one or the other of which was necessary in previous work on upwind schemes for MHD. A test problem made up of a shock tube with rotated initial conditions is solved to show that the two-dimensional code yields answers consistent with the one-dimensional methods developed previously.

Powell, Kenneth G.

1994-01-01

378

A pressure-based high resolution numerical method for resistive MHD  

NASA Astrophysics Data System (ADS)

In the paper we describe in detail a numerical method for the resistive magnetohydrodynamic (MHD) equations involving viscous flow and report the results of application to a number of typical MHD test cases. The method is of the finite volume type but mixes aspects of pressure-correction and density based solvers; the algorithm arrangement is patterned on the well-known PISO algorithm, which is a pressure method, while the flux computation makes use of the AUSM-MHD scheme, which originates from density based methods. Five groups of test cases are addressed to verify and validate the method. We start with two resistive MHD cases, namely the Shercliff and Hunt flow problems, which are intended to validate the method for low-speed resistive MHD flows. The remaining three test cases, namely the cloud-shock interaction, the MHD rotor and the MHD blast wave, are standard 2D ideal MHD problems that serve to validate the method under high-speed flow and complex interaction of MHD shocks. Finally, we demonstrate the method with a more complex application problem, and discuss results of simulation for a quasi-bi-dimensional self-field magnetoplasmadynamic (MPD) thruster, for which we study the effect of cathode length upon the electromagnetic nozzle performance.

Xisto, Carlos M.; Páscoa, José C.; Oliveira, Paulo J.

2014-10-01

379

The role of magnetohydrodynamics in heliospheric space plasma physics research  

NASA Technical Reports Server (NTRS)

Magnetohydrodynamics (MHD) is a fairly recent extension of the field of fluid mechanics. While much remains to be done, it has successfully been applied to the contemporary field of heliospheric space plasma research to evaluate the 'macroscopic picture' of some vital topics via the use of conducting fluid equations and numerical modeling and simulations. Some representative examples from solar and interplanetary physics are described to demonstrate that the continuum approach to global problems (while keeping in mind the assumptions and limitations therein) can be very successful in providing insight and large scale interpretations of otherwise intractable problems in space physics.

Dryer, Murray; Smith, Zdenka Kopal; Wu, Shi Tsan

1988-01-01

380

Initial Condition Sensitivity of Global Quantities in Magnetohydrodynamic Turbulence  

E-print Network

In this paper we study the effect of subtle changes in initial conditions on the evolution of global quantities in two-dimensional Magnetohydrodynamic (MHD) turbulence. We find that a change in the initial phases of complex Fourier modes of the Els\\"{a}sser variables, while keeping the initial values of total energy, cross helicity and Alfv\\'{e}n ratio unchanged, has a significant effect on the evolution of cross helicity. On the contrary, the total energy and Alfv\\'{e}n ratio are insensitive to the initial phases. Our simulations are based on direct numerical simulation using the pseudo-spectral method.

Gaurav Dar; Mahendra K. Verma; V. Eswaran

1998-03-16

381

MAGNETOHYDRODYNAMIC SIMULATION OF A SIGMOID ERUPTION OF ACTIVE REGION 11283  

SciTech Connect

Current magnetohydrodynamic (MHD) simulations of the initiation of solar eruptions are still commonly carried out with idealized magnetic field models, whereas the realistic coronal field prior to eruptions can possibly be reconstructed from the observable photospheric field. Using a nonlinear force-free field extrapolation prior to a sigmoid eruption in AR 11283 as the initial condition in an MHD model, we successfully simulate the realistic initiation process of the eruption event, as is confirmed by a remarkable resemblance to the SDO/AIA observations. Analysis of the pre-eruption field reveals that the envelope flux of the sigmoidal core contains a coronal null and furthermore the flux rope is prone to a torus instability. Observations suggest that reconnection at the null cuts overlying tethers and likely triggers the torus instability of the flux rope, which results in the eruption. This kind of simulation demonstrates the capability of modeling the realistic solar eruptions to provide the initiation process.

Jiang Chaowei; Feng Xueshang [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Wu, S. T.; Hu Qiang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: fengx@spaceweather.ac.cn, E-mail: wus@uah.edu, E-mail: qh0001@uah.edu [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

2013-07-10

382

A renormalization group analysis of two-dimensional magnetohydrodynamic turbulence  

NASA Technical Reports Server (NTRS)

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.

Liang, Wenli Z.; Diamond, P. H.

1993-01-01

383

Self-heating in kinematically complex magnetohydrodynamic flows  

SciTech Connect

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.

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

384

Hamiltonian magnetohydrodynamics: Lagrangian, Eulerian, and dynamically accessible stability—Theory  

SciTech Connect

Stability conditions of magnetized plasma flows are obtained by exploiting the Hamiltonian structure of the magnetohydrodynamics (MHD) equations and, in particular, by using three kinds of energy principles. First, the Lagrangian variable energy principle is described and sufficient stability conditions are presented. Next, plasma flows are described in terms of Eulerian variables and the noncanonical Hamiltonian formulation of MHD is exploited. For symmetric equilibria, the energy-Casimir principle is expanded to second order and sufficient conditions for stability to symmetric perturbation are obtained. Then, dynamically accessible variations, i.e., variations that explicitly preserve invariants of the system, are introduced and the respective energy principle is considered. General criteria for stability are obtained, along with comparisons between the three different approaches.

Andreussi, T. [Alta S.p.A., Pisa 56121 (Italy)] [Alta S.p.A., Pisa 56121 (Italy); Morrison, P. J. [Institute for Fusion Studies and Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1060 (United States)] [Institute for Fusion Studies and Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1060 (United States); Pegoraro, F. [Università di Pisa, Dipartimento di Fisica E. Fermi, Pisa 56127 (Italy)] [Università di Pisa, Dipartimento di Fisica E. Fermi, Pisa 56127 (Italy)

2013-09-15

385

A two-component phenomenology for homogeneous magnetohydrodynamic turbulence  

SciTech Connect

A one-point closure model for energy decay in three-dimensional magnetohydrodynamic (MHD) turbulence is developed. The model allows for influence of a large-scale magnetic field that may be of strength sufficient to induce Alfven wave propagation effects, and takes into account components of turbulence in which either the wave-like character is negligible or is dominant. This two-component model evolves energy and characteristic length scales, and may be useful as a simple description of homogeneous MHD turbulent decay. In concert with spatial transport models, it can form the basis for approximate treatment of low-frequency plasma turbulence in a variety of solar, space, and astrophysical contexts.

Oughton, S.; Dmitruk, P.; Matthaeus, W. H. [Department of Mathematics, University of Waikato, Private Bag 3105, Hamilton (New Zealand); Bartol Research Institute, University of Delaware, Newark, Delaware 19716 (United States)

2006-04-15

386

Nonlinear closures for scale separation in supersonic magnetohydrodynamic turbulence  

E-print Network

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...

Grete, Philipp; Schmidt, Wolfram; Schleicher, Dominik R G; Federrath, Christoph

2015-01-01

387

Thermoacoustic magnetohydrodynamic electrical generator  

DOEpatents

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.

Wheatley, John C. (Los Alamos, NM); Swift, Gregory W. (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)

1986-01-01

388

Thermoacoustic magnetohydrodynamic electrical generator  

DOEpatents

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 1000 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.

Wheatley, J.C.; Swift, G.W.; Migliori, A.

1984-11-16

389

Operational analysis of open-cycle MHD  

Microsoft Academic Search

Open cycle magnetohydrodynamic (OCMHD) conceptual power plant designs are studied in the context of a utility system to form a better basis for understanding their design, design requirements, and market possibilities. Based on assumed or projected plant costs and performance characteristics, assumed economics and escalation factors, and one coal supply and delivery scenario, overall and regional OCMHD utility market possibilities

T. E. Lippert; D. A. McCutchan

1980-01-01

390

Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Airbreathing Hypersonic Engines  

NASA Technical Reports Server (NTRS)

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.

Litchford, Ron J.; Bityurin, Valentine A.; Lineberry, John T.

1999-01-01

391

Magnetic Discontinuities in Magnetohydrodynamic Turbulence and in the Solar Wind  

E-print Network

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.

Vladimir Zhdankin; Stanislav Boldyrev; Joanne Mason; Jean Carlos Perez

2012-04-19

392

Resistive jet simulations extending radially self-similar magnetohydrodynamic models  

NASA Astrophysics Data System (ADS)

Numerical simulations with self-similar initial and boundary conditions provide a link between theoretical and numerical investigations of jet dynamics. We perform axisymmetric resistive magnetohydrodynamic (MHD) simulations for a generalized solution of the Blandford & Payne type, and compare them with the corresponding analytical and numerical ideal MHD solutions. We disentangle the effects of the numerical and physical diffusivity. The latter could occur in outflows above an accretion disc, being transferred from the underlying disc into the disc corona by MHD turbulence (anomalous turbulent diffusivity), or as a result of ambipolar diffusion in partially ionized flows. We conclude that while the classical magnetic Reynolds number Rm measures the importance of resistive effects in the induction equation, a new introduced number, R? = (?/2)Rm with ? the plasma beta, measures the importance of the resistive effects in the energy equation. Thus, in magnetized jets with ? < 2, when R? <~ 1 resistive effects are non-negligible and affect mostly the energy equation. The presented simulations indeed show that for a range of magnetic diffusivities corresponding to R? >~ 1, the flow remains close to the ideal MHD self-similar solution.

?emelji?, M.; Gracia, J.; Vlahakis, N.; Tsinganos, K.

2008-09-01

393

USING FARADAY ROTATION TO PROBE MAGNETOHYDRODYNAMIC INSTABILITIES IN INTRACLUSTER MEDIA  

SciTech Connect

It has recently been suggested that conduction-driven magnetohydrodynamic (MHD) instabilities may operate at all radii within an intracluster medium (ICM) and profoundly affect the structure of a cluster's magnetic field. Where MHD instabilities dominate the dynamics of an ICM, they will re-orient magnetic field lines perpendicular to the temperature gradient inside a cooling core or parallel to the temperature gradient outside it. This characteristic structure of magnetic field could be probed by measurements of polarized radio emission from background sources. Motivated by this possibility we have constructed three-dimensional models of a magnetized cooling-core cluster and calculated Faraday rotation measure (RM) maps in the plane of the sky under realistic observing conditions. We compare a scenario in which magnetic field geometry is characterized by conduction-driven MHD instabilities to that where it is determined by isotropic turbulent motions. We find that future high-sensitivity spectropolarimetric measurements of RM, such as will be enabled by the Expanded Very Large Array and Square Kilometer Array, can distinguish between these two cases with plausible exposure times. Such observations will test the existence of conduction-driven MHD instabilities in dynamically relaxed cooling-core clusters. More generally, our findings imply that observations of Faraday RM should be able to discern physical mechanisms that result in qualitatively different magnetic field topologies, without a priori knowledge about the nature of the processes.

Bogdanovic, Tamara; Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Massey, Richard, E-mail: tamarab@astro.umd.edu [Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)

2011-04-10

394

Multidimensional HLLE Riemann solver: Application to Euler and magnetohydrodynamic flows  

NASA Astrophysics Data System (ADS)

In this work we present a general strategy for constructing multidimensional HLLE Riemann solvers, with particular attention paid to detailing the two-dimensional HLLE Riemann solver. This is accomplished by introducing a constant resolved state between the states being considered, which introduces sufficient dissipation for systems of conservation laws. Closed form expressions for the resolved fluxes are also provided to facilitate numerical implementation. The Riemann solver is proved to be positively conservative for the density variable; the positivity of the pressure variable has been demonstrated for Euler flows when the divergence in the fluid velocities is suitably restricted so as to prevent the formation of cavitation in the flow. We also focus on the construction of multidimensionally upwinded electric fields for divergence-free magnetohydrodynamical (MHD) flows. A robust and efficient second order accurate numerical scheme for two and three-dimensional Euler and MHD flows is presented. The scheme is built on the current multidimensional Riemann solver and has been implemented in the author's RIEMANN code. The number of zones updated per second by this scheme on a modern processor is shown to be cost-competitive with schemes that are based on a one-dimensional Riemann solver. However, the present scheme permits larger timesteps. Accuracy analysis for multidimensional Euler and MHD problems shows that the scheme meets its design accuracy. Several stringent test problems involving Euler and MHD flows are also presented and the scheme is shown to perform robustly on all of them.

Balsara, Dinshaw S.

2010-03-01

395

An Experimental MHD Dynamo  

SciTech Connect

The project is designed to understand current and magnetic field generation in plasmas and other magnetohydrodynamic systems. The experiments will investigate the generation of a dynamo using liquid Na.

Forest, C. B.

2002-11-15

396

The Parabolic Jet Structure in M87 as a Magnetohydrodynamic Nozzle  

NASA Astrophysics Data System (ADS)

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 & 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 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 ~103 r s, while the upstream trans-Alfvénic flow speed increases linearly as a function of the distance at ~102-103 r 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.

Nakamura, Masanori; Asada, Keiichi

2013-10-01

397

THE PARABOLIC JET STRUCTURE IN M87 AS A MAGNETOHYDRODYNAMIC NOZZLE  

SciTech Connect

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.

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

398

Relativistic magnetohydrodynamics in dynamical spacetimes: A new adaptive mesh refinement implementation  

NASA Astrophysics Data System (ADS)

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 ?·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 ?·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 Alfvén 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.

Etienne, Zachariah B.; Liu, Yuk Tung; Shapiro, Stuart L.

2010-10-01

399

MHD normal mode analysis with equilibrium pressure anisotropy  

NASA Astrophysics Data System (ADS)

In this work, we generalise linear magnetohydrodynamic (MHD) stability theory to include equilibrium pressure anisotropy in the fluid part of the analysis. A novel ‘single-adiabatic’ (SA) fluid closure is presented which is complementary to the usual ‘double-adiabatic’ (CGL) model and has the advantage of naturally reproducing exactly the MHD spectrum in the isotropic limit. As with MHD and CGL, the SA model neglects the anisotropic perturbed pressure and thus loses non-local fast-particle stabilisation present in the kinetic approach. Another interesting aspect of this new approach is that the stabilising terms appear naturally as separate viscous corrections leaving the isotropic SA closure unchanged. After verifying the self-consistency of the SA model, we re-derive the projected linear MHD set of equations required for stability analysis of tokamaks in the MISHKA code. The cylindrical wave equation is derived analytically as done previously in the spectral theory of MHD and clear predictions are made for the modification to fast-magnetosonic and slow ion sound speeds due to equilibrium anisotropy.

Fitzgerald, M.; Hole, M. J.; Qu, Z. S.

2015-02-01

400

Results from a large-scale MHD propulsion experiment  

NASA Astrophysics Data System (ADS)

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

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

401

MHD aspects of fire-hose type instabilities  

NASA Astrophysics Data System (ADS)

In a homogeneous anisotropic plasma the magnetohydrodynamic (MHD) Alfvén wave may become unstable for p? > pperpendicular to + B2/? 0. Recently a new type of fire-hose instability is found by Hellinger and Matsumoto [2000] that has maximum growth rate occurring for oblique propagation and may grow faster than the Alfvén mode. This new mode is compressional and may be more efficient at destroying pressure anisotropy than the standard fire hose. In this study we examines the fire-hose type (p? > pperpendicular to ) instabilities based on the linear and nonlinear double-polytropic MHD theory. It is shown that there exist two types of MHD fire-hose instabilities associated with the intermediate and slow modes, respectively, and with suitable choice of polytropic exponents the linear instability criteria become the same as those based on the Vlasov theory in the hydromagnetic limit. Moreover, the properties of the nonlinear MHD fire-hose instabilities are found to have great similarities with those obtained from the kinetic theory and hybrid simulation. In particular, the classical fire-hose instability evolves toward the linear fire-hose stability threshold while the nonlinear marginal stability associated with the new fire hose is well below the condition of ? ? - ? perpendicular to = 2 but complies with less stringent linear stability threshold for MHD slow-mode wave.

Wang, B.; Hau, L.

2003-12-01

402

Nonlocality and the critical Reynolds numbers of the minimum state magnetohydrodynamic turbulence  

SciTech Connect

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.

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

403

Energy fluxes and shell-to-shell transfers in three-dimensional decaying magnetohydrodynamic turbulence  

SciTech Connect

A spectral analysis of the energy cascade in magnetohydrodynamics (MHD) is presented using high-resolution direct numerical simulation of decaying isotropic turbulence. The Fourier representations of both the velocity and the magnetic fields are split into subsets that correspond to shells of wave vectors. A detailed study of the shell-to-shell interactions is performed and a comparison with theoretical prediction based on field-theoretic method is proposed. Two different definitions for the forward and backward energy transfers are suggested. They provide diagnostics that can be used in order to assess subgrid-scale modeling in large eddy simulation for turbulent MHD systems.

Debliquy, Olivier; Verma, Mahendra K.; Carati, Daniele [Statistical and Plasma Physics, Universite Libre de Bruxelles, CP231, Campus Plaine, 1050 Brussels (Belgium); Department of Physics, Indian Institute of Technology, Kanpur 208016, (India); Statistical and Plasma Physics, Universite Libre de Bruxelles, CP231, Campus Plaine, 1050 Brussels (Belgium)

2005-04-15

404

Variational integration for ideal magnetohydrodynamics with built-in advection equations  

SciTech Connect

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.

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

405

Variational integration for ideal magnetohydrodynamics with built-in advection equations  

NASA Astrophysics Data System (ADS)

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.

Zhou, Yao; Qin, Hong; Burby, J. W.; Bhattacharjee, A.

2014-10-01

406

Application of scalar implicit approximate factorization for underwater magnetohydrodynamic propulsion concept analyses  

SciTech Connect

Numerical procedures have been developed to analyze multidimensional flow and imposed electromagnetic fields associated with a marine magnetohydrodynamic (MHD) propulsion concept. Chorin's artificial compressibility treatment is applied to determine the incompressible flowfield both internal and external to the MHD thruster, using a zonal formulation. Both inviscid and viscous flow are considered. Determination of three-dimensional magnetic, electric, and Lorentz force fields is based on suitable idealizations. This provides indicative results without getting into detailed sytem design considerations. Among other conclusions, it is established that secondary flow induced by the nonuniform Lorentz force is not a key issue in the magnet end-turn regions. 17 refs.

Choi, D.; Knight, C.J. (Textron Defense Systems, Everett, MA (United States))

1993-02-01

407

Experimental determination of magnetohydrodynamic seawater thruster performance in a two Tesla test facility  

SciTech Connect

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.

Picologlou, B.; Doss, E.; Black, D. (Argonne National Lab., IL (United States)); Sikes, W.C. (Newport News Shipbuilding and Dry Dock Co., VA (United States))

1992-01-01

408

Experimental determination of magnetohydrodynamic seawater thruster performance in a two Tesla test facility  

SciTech Connect

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.

Picologlou, B.; Doss, E.; Black, D. [Argonne National Lab., IL (United States); Sikes, W.C. [Newport News Shipbuilding and Dry Dock Co., VA (United States)

1992-09-01

409

Experimental determination of magnetohydrodynamic seawater thruster performance in a two Tesla test facility  

NASA Astrophysics Data System (ADS)

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.

Picologlou, B.; Doss, E.; Black, D.; Sikes, W. C.

1992-08-01

410

Maximal energies of the particles accelerated by the system of converging magnetohydrodynamic flows  

NASA Astrophysics Data System (ADS)

We have shown that maximal energies of the charged particles accelerated in the system of converging magnetohydrodynamic (MHD) flows can reach ? 1017 eV. The scheme of magnetic field amplification (MFA) applied to the previous non-linear model of particle acceleration in the colliding shocks allowed to make proper estimates for the value of turbulent magnetic field. The efficiency of the particle acceleration on the energy range larger than the "knee" in the cosmic rays spectrum (? 1014 – 1015 eV) makes the systems of colliding MHD flows important contributors to the overall high-energy cosmic rays population in the Galaxy.

Gladilin, P. E.; Bykov, A. M.; Osipov, S. M.

2014-12-01

411

Trigonometric and hyperbolic functions method for constructing analytic solutions to nonlinear plane magnetohydrodynamics equilibrium equations  

NASA Astrophysics Data System (ADS)

In this paper, we present a solution method for constructing exact analytic solutions to magnetohydrodynamics (MHD) equations. The method is constructed via all the trigonometric and hyperbolic functions. The method is applied to MHD equilibria with mass flow. Applications to a solar system concerned with the properties of coronal mass ejections that affect the heliosphere are presented. Some examples of the constructed solutions which describe magnetic structures of solar eruptions are investigated. Moreover, the constructed method can be applied to a variety classes of elliptic partial differential equations which arise in plasma physics.

Moawad, S. M.

2015-02-01

412

Performance Evaluation of Lattice-Boltzmann MagnetohydrodynamicsSimulations on Modern Parallel Vector Systems  

SciTech Connect

The last decade has witnessed a rapid proliferation of superscalarcache-based microprocessors to build high-end computing (HEC) platforms, primarily because of their generality, scalability, and cost effectiveness. However, the growing gap between sustained and peak performance for full-scale scientific applications on such platforms has become major concern in high performance computing. The latest generation of custom-built parallel vector systems have the potential to address this concern for numerical algorithms with sufficient regularity in their computational structure. In this work, we explore two and three dimensional implementations of a lattice-Boltzmann magnetohydrodynamics (MHD) physics application, on some of today's most powerful supercomputing platforms. Results compare performance between the vector-based Cray X1, Earth Simulator, and newly-released NEC SX-8, with the commodity-based superscalar platforms of the IBM Power3, IntelItanium2, and AMD Opteron. Overall results show that the SX-8 attains unprecedented aggregate performance across our evaluated applications.

Carter, Jonathan; Oliker, Leonid

2006-01-09

413

Immersed boundary method for the MHD flows of liquid metals  

NASA Astrophysics Data System (ADS)

Wall-bounded magnetohydrodynamic (MHD hereafter) flows are of great theoretical and practical interest. Even for laminar cases, MHD simulations are associated with very high computational cost due to the resolution requirements for the Hartmann and side layers developing in the presence of solid obstacles. In the presence of turbulence, these difficulties are further compounded. Thus, MHD simulations in complex geometries are currently a challenge. The immersed boundary (IB hereafter) method is a reliable numerical tool for efficient hydrodynamic field simulations in arbitrarily geometries, but it has not yet been extended for MHD simulations. The present study forms the first attempt to apply the IB methodology for the computation of both the hydrodynamic and MHD fields. A consistent numerical methodology is presented that is appropriate for efficient 3D MHD simulations in geometrically complicated domains using cartesian flow solvers. For that purpose, a projection scheme for the electric current density is presented, based on an electric potential correction algorithm. A suitable forcing scheme for electric density currents in the vicinity of non-conducting immersed surfaces is also proposed. The proposed methodology has been first extensively tested for Hartmann layers in fully-developed and developing channel and duct flows at Hartmann numbers Ha=500-2000. In order to demonstrate the potential of the method, the three-dimensional MHD flow around a circular cylinder at Reynolds number Re=200 is also presented. The effects of grid resolution and variable arrangement on the simulation accuracy and consistency were examined. When compared with existing numerical or analytic solutions, excellent agreement was found for all the cases considered. The proposed projection and forcing schemes for current densities were found capable of satisfying the charge conservation law in the presence of immersed non-conducting boundaries. Finally, we show how the proposed methodology can be used to extend the applicability of existing flow solvers that use the IB concept with a staggered variable arrangement.

Grigoriadis, D. G. E.; Kassinos, S. C.; Votyakov, E. V.

2009-02-01

414

Center for Extended Magnetohydrodynamic Modeling Cooperative Agreement  

SciTech Connect

The Center for Extended Magnetohydrodynamic Modeling (CEMM) is developing computer simulation models for predicting the behavior of magnetically confined plasmas. Over the first phase of support from the Department of Energy’s Scientific Discovery through Advanced Computing (SciDAC) initiative, the focus has been on macroscopic dynamics that alter the confinement properties of magnetic field configurations. The ultimate objective is to provide computational capabilities to predict plasma behavior—not unlike computational weather prediction—to optimize performance and to increase the reliability of magnetic confinement for fusion energy. Numerical modeling aids theoretical research by solving complicated mathematical models of plasma behavior including strong nonlinear effects and the influences of geometrical shaping of actual experiments. The numerical modeling itself remains an area of active research, due to challenges associated with simulating multiple temporal and spatial scales. The research summarized in this report spans computational and physical topics associated with state of the art simulation of magnetized plasmas. The tasks performed for this grant are categorized according to whether they are primarily computational, algorithmic, or application-oriented in nature. All involve the development and use of the Non-Ideal Magnetohydrodynamics with Rotation, Open Discussion (NIMROD) code, which is described at http://nimrodteam.org. With respect to computation, we have tested and refined methods for solving the large algebraic systems of equations that result from our numerical approximations of the physical model. Collaboration with the Terascale Optimal PDE Solvers (TOPS) SciDAC center led us to the SuperLU_DIST software library [http://crd.lbl.gov/~xiaoye/SuperLU/] for solving large sparse matrices using direct methods on parallel computers. Switching to this solver library boosted NIMROD’s performance by a factor of five in typical large nonlinear simulations, which has been publicized as a success story of SciDAC-fostered collaboration. Furthermore, the SuperLU software does not assume any mathematical symmetry, and its generality provides an important capability for extending the physical model beyond magnetohydrodynamics (MHD). With respect to algorithmic and model development, our most significant accomplishment is the development of a new method for solving plasma models that treat electrons as an independent plasma component. These ‘two-fluid’ models encompass MHD and add temporal and spatial scales that are beyond the response of the ion species. Implementation and testing of a previously published algorithm did not prove successful for NIMROD, and the new algorithm has since been devised, analyzed, and implemented. Two-fluid modeling, an important objective of the original NIMROD project, is now routine in 2D applications. Algorithmic components for 3D modeling are in place and tested; though, further computational work is still needed for efficiency. Other algorithmic work extends the ion-fluid stress tensor to include models for parallel and gyroviscous stresses. In addition, our hot-particle simulation capability received important refinements that permitted completion of a benchmark with the M3D code. A highlight of our applications work is the edge-localized mode (ELM) modeling, which was part of the first-ever computational Performance Target for the DOE Office of Fusion Energy Science, see http://www.science.doe.gov/ofes/performancetargets.shtml. Our efforts allowed MHD simulations to progress late into the nonlinear stage, where energy is conducted to the wall location. They also produced a two-fluid ELM simulation starting from experimental information and demonstrating critical drift effects that are characteristic of two-fluid physics. Another important application is the internal kink mode in a tokamak. Here, the primary purpose of the study has been to benchmark the two main code development lines of CEMM, NIMROD and M3D, on a relevant nonlinear problem. Results from the two

Carl R. Sovinec

2008-02-15

415

Adiabatically reduced magnetohydrodynamic equations for a cylindrical plasma with an anisotropic pressure  

SciTech Connect

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.

Nebogatov, V. A.; Pastukhov, V. P., E-mail: past@nfi.kiae.ru [National Research Centre Kurchatov Institute (Russian Federation)

2013-06-15

416

Ellipticity of axisymmetric equilibria with flow and pressure anisotropy in single-fluid and Hall magnetohydrodynamics  

SciTech Connect

The ellipticity criteria for the partial differential equations of axisymmetric single-fluid and Hall magnetohydrodynamic (MHD) equilibria with flow and pressure anisotropy are investigated. The MHD systems are closed with cold ions and electron pressures derived from their parallel heat flux equations, a closure that reproduces the corresponding kinetic dispersion relation. In the single-fluid model, which differs from the double-adiabatic Chew-Goldberger-Low model, it is verified that the elliptic region boundaries occur at poloidal flow velocities equal to wave velocities from the kinetic dispersion relation. For Hall magnetohydrodynamics, a set of anisotropic-pressure equilibrium equations is derived and an ellipticity condition corresponding to a poloidal flow velocity slightly smaller than the ion sound velocity is obtained.

Ito, Atsushi; Ramos, Jesus J.; Nakajima, Noriyoshi [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

2007-06-15

417

Time evolution from linear to nonlinear stages in magnetohydrodynamic parametric instabilities  

NASA Technical Reports Server (NTRS)

The nonlinear evolution of the magnetohydrodynamic (MHD) parametric instability of wave fluctuations propagating along an unperturbed magnetic field is investigated. Both a magnetohydrodynamic perturbation-theoretical approach and a nonlinear MHD simulation are used. It is shown that high harmonic waves are rapidly excited by wave-wave coupling, and that the wave spectrum evolves from a state containing a small number of degrees of freedom in k space to one which contains a large number of degrees of freedom. It is found that the spectral evolution prior to nonlinear saturation is well described by the prturbation theory. During this stage, the ratio of the growth rate of the nth harmonic wave to the linear growth rate of the fundamental wave is n. The nonlinear saturation stage is characterized by a frequency shift of the fundamental wave that destroys the wave-wave resonance condition which, in turn, causes the wave amplitude to cease its growth.

Hoshino, M.; Goldstein, M. L.

1989-01-01

418

MHD Integrated Topping Cycle Project  

SciTech Connect

This eighteenth quarterly technical progress report of the MHD Integrated Topping cycle Project presents the accomplishments during the period November 1, 1991 to January 31, 1992. The precombustor is fully assembled. Manufacturing of all slagging stage components has been completed. All cooling panels were welded in place and the panel/shell gap was filled with RTV. Final combustor assembly is in progress. The low pressure cooling subsystem (LPCS) was delivered to the CDIF. Second stage brazing issues were resolved. The construction of the two anode power cabinets was completed.

Not Available

1992-07-01

419

Statistical characterization of the interchange-instability spectrum of a separable ideal-magnetohydrodynamic model system  

E-print Network

-magnetohydrodynamic model system R. L. Dewar,1,2, * T. Tatsuno,3,2 Z. Yoshida,2 C. Nührenberg,4 and B. F. McMillan1 1 the eigenvalues there depend only on m and n as in a two-dimensional system. However, unlike the generic separable two-dimensional system, the statistics of the ideal-MHD spectrum departs somewhat from the Poisson

Tatsuno, Tomoya

420

Magnetohydrodynamic waves in a compressible magnetic flux tube with elliptical cross-section  

Microsoft Academic Search

Aims: The propagation of magnetohydrodynamic (MHD) waves in a finite, compressible magnetic flux tube with an elliptical cross-section embedded in a magnetic environment is investigated. Methods: We present the derivation of the general dispersion relation of linear magneto-acoustic wave propagation for a compressible magnetic flux tube with elliptical cross-section in a plasma with finite beta. The wave modes of propagation

R. Erdélyi; R. J. Morton

2009-01-01

421

New Computational Dynamics for Magnetohydrodynamics Flow over a Nonlinear Stretching Sheet  

NASA Astrophysics Data System (ADS)

The main idea of the present article is to introduce a new computational technique, explicitly, the modified Laplace Pa&dacute;e decomposition method (MLPDM) which is a recipe of Laplace transformation, decomposition technique, and rational polynomial to offer new solution mechanism of magnetohydrodynamics (MHD) flow of an steady viscous, incompressible nonlinear stretching sheet. A good harmony among the attained solution and the exact solution has been verified.

Khan, Majid; Gondal, Muhammad Asif

2012-05-01

422

High-beta operation and magnetohydrodynamic activity on the TFTR tokamak  

Microsoft Academic Search

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

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

423

New exact solutions for magnetohydrodynamic flows of an Oldroyd-B fluid  

Microsoft Academic Search

.  This paper presents the new exact analytical solutions for magnetohydrodynamic (MHD) flows of an Oldroyd-B fluid. The explicit\\u000a expressions for the velocity field and the associated tangential stress are established by using the Laplace transform method.\\u000a Three characteristic examples: (i) flow due to impulsive motion of plate, (ii) flow due to uniformly accelerated plate, and (iii) flow due to non-uniformly

M. Khan; Sidra Mahmood; C. Fetecau

2009-01-01

424

Results of large scale MHD generator experiments  

Microsoft Academic Search

A high performance demonstration experiment (HPDE) is in progress to prove that a 300-MW thermal input open-cycle MHD system generator can convert a percent of the available thermal energy into electrical power. The facility is described in detail: combustor system, the magnet system, the generator channel, the HPDE diffuser, and an HPDE data system. The run sequence includes cooling water

G. L. Whitehead; L. S. Christensen

1982-01-01

425

MHD pressure drops and thermal hydraulic analysis for the ITER breeding blanket design  

SciTech Connect

The breeding blanket design of the International Thermonuclear Experimental Reactor (ITER) is a self-cooled liquid lithium system with a vanadium structure. Electrical insulation of the coolant channel surfaces from the liquid metal is required to reduce the magnetohydrodynamic (MHD) pressure to less than 1 MPa. Insulation is provided by AIN coating at the channel surfaces in contact with lithium. MHD pressure drop and thermal hydraulic analysis of the blanket design is carried out subject to pressure, temperature, and stress considerations. Design windows relating the lithium flow velocity, MHD pressure, and structural temperature are formulated. The requirements of the insulator coating and characterization of the coating effectiveness are presented. Effects on the MHD pressure drop due to uniform cracks through the coating layer is also analyzed.

Hua, Thanh Q. [Argonne National Lab., IL (United States); Gohar, Y. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany). International Thermonuclear Experimental Reactor (ITER)

1994-06-01

426

Magnetohydrodynamic generator experimental studies  

NASA Technical Reports Server (NTRS)

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.

Pierson, E. S.

1972-01-01

427

EFFECTS OF HALL CURRENT ON MHD FLOW IN A ROTATING CHANNEL PARTIALLY FILLED WITH A POROUS MEDIUM  

Microsoft Academic Search

In a rotating system, magnetohydrodynamic fully developed flow in a parallel-plate channel partially filled with a fluid-saturated porous medium and partially with a clear fluid is considered in the presence of an inclined magnetic field. Hall effects are taken into account and exact solutions of the governing MHD differential equations are obtained in a closed form. The effects of pertinent

Dileep Singh Chauhan; Rashmi Agrawal

2010-01-01

428

Reconnection at the dayside magnetopause: Comparisons of global MHD simulation results with Cluster and Double Star observations  

Microsoft Academic Search

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

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

429

Cavities of Weak Magnetic Field Strength in the Wake of FTEs: Results from Global Magnetospheric MHD Simulations  

NASA Technical Reports Server (NTRS)

We use the global magnetohydrodynamic (MHD) code BATS-R-US to model multipoint observations of Flux Transfer Event (FTE) signatures. Simulations with high spatial and temporal resolution predict that cavities of weak magnetic field strength protruding into the magnetosphere trail FTEs. These predictions are consistent with recently reported multi-point Cluster observations of traveling magnetopause erosion regions (TMERs).

Kuznetsova, M. M.; Sibeck, D. G.; Hesse, M.; Wang, Y.; Rastaetter, L.; Toth, G.; Ridley, A.

2009-01-01

430

Reconnection at the dayside magnetopause: Comparisons of global MHD simulation results with Cluster and Double Star observations  

Microsoft Academic Search

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 By components. The first event occurred on 8 May 2004, while both spacecraft were exploring the dawn flank of the magnetosphere;

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

431

Exact solutions for MHD flow of generalized Oldroyd-B fluid due to an infinite accelerating plate  

Microsoft Academic Search

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

Liancun Zheng; Yaqing Liu; Xinxin Zhang

2011-01-01

432

The PIERNIK MHD code - a multi-fluid, non-ideal extension of the relaxing-TVD scheme (II)  

Microsoft Academic Search

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

Micha? Hanasz; Kacper Kowalik; D. Wóltanski; R. Pawlaszek; Kacper Kornet

2010-01-01

433

Superheater/intermediate temperature airheater tube corrosion tests in the MHD Coal Fired Flow Facility (Eastern Coal Phase)  

SciTech Connect

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.

White, M.K.

1993-11-01

434

Reduced-MHD Simulations of Toroidally and Poloidally Localized ELMs  

E-print Network

Edge localized modes (ELMs) accompany the high-confinement mode (H-mode) in tokamak fusion plasmas. While having the favourable property of removing impurities from the plasma, they can also cause excessive heat loads onto first-wall and divertor structures. Modelling these instabilities in non-linear magneto-hydrodynamic (MHD) simulations and comparing the results to experimental measurements can contribute to an improved understanding of ELMs. We use the non-linear reduced-MHD code JOREK to study ELMs in the geometry of the ASDEX Upgrade tokamak. Toroidal mode numbers, poloidal filament sizes, and radial propagation speeds of filaments into the scrape-off layer are in good agreement with observations for type-I ELMs in ASDEX Upgrade. The observed instabilities exhibit a localization of perturbations which is compatible with the "solitary magnetic perturbations" recently discovered in ASDEX Upgrade [R.Wenninger et.al., Solitary Magnetic Perturbations at the ELM Onset, Nucl.Fusion, submitted]. This localizati...

Hoelzl, Matthias; Wenninger, Ronald P; Mueller, Wolf-Christian; Huysmans, Guido T A; Lackner, Karl

2012-01-01

435

Photospheric Logarithmic Velocity Spirals as MHD Wave Generation Mechanisms  

E-print Network

High-resolution observations of the solar photosphere have identified a wide variety of spiralling motions in the plasma. These spirals vary in properties, but are observed to be abundant on the solar surface. In this work these spirals are studied for their potential as magnetohydrodynamic (MHD) wave generation mechanisms. The inter-granular lanes, where these spirals are commonly observed, are also regions where the magnetic field strength is higher than average. This combination of magnetic field and spiralling plasma is a recipe for the generation of Alfv\\'en waves and other MHD waves. This work employs numerical simulations of a self-similar magnetic flux tube embedded in a realistic, gravitationally stratified, solar atmosphere to study the effects of a single magnetic flux tube perturbed by a logarithmic velocity spiral driver. The expansion factor of the logarithmic spiral driver is varied, multiple simulations are run for a range of values of the expansion factor centred around observational data. Th...

Mumford, S J

2015-01-01

436

On the Yudovich solutions for the ideal MHD equations  

NASA Astrophysics Data System (ADS)

In this paper, we address the problem of weak solutions of Yudovich type for the inviscid magnetohydrodynamic (MHD) equations in two dimensions. The local-in-time existence and uniqueness of these solutions sound to be hard to achieve due to some terms involving Riesz transforms in the vorticity–current formulation. We shall prove that the vortex patches with smooth boundary offer a suitable class of initial data for which the problem can be solved. However, this is only done under a geometric constraint by assuming the boundary of the initial vorticity to be frozen in a magnetic field line. We shall also discuss the stationary patches for the incompressible Euler system (E) and the MHD system. For example, we prove that a stationary simply connected patch with rectifiable boundary for the system (E) is necessarily the characteristic function of a disc.

Hmidi, Taoufik

2014-12-01

437

Magnetic control of magnetohydrodynamic instabilities in tokamaks  

NASA Astrophysics Data System (ADS)

Externally applied, non-axisymmetric magnetic fields form the basis of several relatively simple and direct methods to control magnetohydrodynamic (MHD) instabilities in a tokamak, and most present and planned tokamaks now include a set of non-axisymmetric control coils for application of fields with low toroidal mode numbers. Non-axisymmetric applied fields are routinely used to compensate small asymmetries ( ?B /B ˜10-3 to 10-4 ) of the nominally axisymmetric field, which otherwise can lead to instabilities through braking of plasma rotation and through direct stimulus of tearing modes or kink modes. This compensation may be feedback-controlled, based on the magnetic response of the plasma to the external fields. Non-axisymmetric fields are used for direct magnetic stabilization of the resistive wall mode—a kink instability with a growth rate slow enough that feedback control is practical. Saturated magnetic islands are also manipulated directly with non-axisymmetric fields, in order to unlock them from the wall and spin them to aid stabilization, or position them for suppression by localized current drive. Several recent scientific advances form the foundation of these developments in the control of instabilities. Most fundamental is the understanding that stable kink modes play a crucial role in the coupling of non-axisymmetric fields to the plasma, determining which field configurations couple most strongly, how the coupling depends on plasma conditions, and whether external asymmetries are amplified by the plasma. A major advance for the physics of high-beta plasmas ( ? = plasma pressure/magnetic field pressure) has been the understanding that drift-kinetic resonances can stabilize the resistive wall mode at pressures well above the ideal-MHD stability limit, but also that such discharges can be very sensitive to external asymmetries. The common physics of stable kink modes has brought significant unification to the topics of static error fields at low beta and resistive wall modes at high beta. These and other scientific advances, and their application to control of MHD instabilities, will be reviewed with emphasis on the most recent results and their applicability to ITER.

Strait, E. J.

2015-02-01

438

Imbalanced Weak MHD Turbulence  

E-print Network

MHD turbulence consists of waves that propagate along magnetic fieldlines, in both directions. When two oppositely directed waves collide, they distort each other, without changing their respective energies. In weak MHD turbulence, a given wave suffers many collisions before cascading. "Imbalance" means that more energy is going in one direction than the other. In general, MHD turbulence is imbalanced. A number of complications arise for the imbalanced cascade that are unimportant for the balanced one. We solve weak MHD turbulence that is imbalanced. Of crucial importance is that the energies going in both directions are forced to equalize at the dissipation scale. We call this the "pinning" of the energy spectra. It affects the entire inertial range. Weak MHD turbulence is particularly interesting because perturbation theory is applicable. Hence it can be described with a simple kinetic equation. Galtier et al. (2000) derived this kinetic equation. We present a simpler, more physical derivation, based on the picture of colliding wavepackets. In the process, we clarify the role of the zero-frequency mode. We also explain why Goldreich & Sridhar claimed that perturbation theory is inapplicable, and why this claim is wrong. (Our "weak" is equivalent to Goldreich & Sridhar's "intermediate.") We perform numerical simulations of the kinetic equation to verify our claims. We construct simplified model equations that illustrate the main effects. Finally, we show that a large magnetic Prandtl number does not have a significant effect, and that hyperviscosity leads to a pronounced bottleneck effect.

Yoram Lithwick; Peter Goldreich

2002-08-02

439