Magnetohydrodynamic power generation
NASA Technical Reports Server (NTRS)
Smith, J. L.
1984-01-01
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.
NASA Technical Reports Server (NTRS)
1981-01-01
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
NASA Astrophysics Data System (ADS)
1981-09-01
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
Legro, J.R.; Abi-Samra, N.C.; Crouse, J.C.; Tesche, F.M.
1985-01-01
This paper summarizes a method to evaluate the possible effects of magnetohydrodynamic-electromagnetic pulse (MHD-EMP) on power systems. This method is based on the approach adapted to study the impact of geomagnetic storms on power systems. The paper highlights the similarities and differences between the two phenomena. Also presented are areas of concern which are anticipated from MHD-EMP on the overall system operation. 12 refs., 1 fig.
Barnes, P.R. ); Tesche, F.M. , Dallas, TX ); Vance, E.F. , Fort Worth, TX )
1992-03-01
A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth's magnetic field and produces a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). This can adversely affect electrical power systems. In this report, the effects of this nuclear environment on critical facilities connected to the commercial power system are considered. Methods of mitigating the MHD-EMP impacts are investigated, and recommended protection schemes are presented. Guidelines for testing facilities to determine the effects of MHD-EMP and to validate the mitigation methods also are discussed.
NASA Astrophysics Data System (ADS)
Barnes, P. R.; Tesche, F. M.; Vance, E. F.
1992-03-01
A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth's magnetic field and produces a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). This can adversely affect electrical power systems. In this report, the effects of this nuclear environment on critical facilities connected to the commercial power system are considered. Methods of mitigating the MHD-EMP impacts are investigated, and recommended protection schemes are presented. Guidelines for testing facilities to determine the effects of MHD-EMP and to validate the mitigation methods also are discussed.
Parametric analysis of closed cycle magnetohydrodynamic (MHD) power plants
NASA Technical Reports Server (NTRS)
Owens, W.; Berg, R.; Murthy, R.; Patten, J.
1981-01-01
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.
Barnes, P.R.; Tesche, F.M.; Vance, E.F.
1992-03-01
A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth`s magnetic field and produces a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). This can adversely affect electrical power systems. In this report, the effects of this nuclear environment on critical facilities connected to the commercial power system are considered. Methods of mitigating the MHD-EMP impacts are investigated, and recommended protection schemes are presented. Guidelines for testing facilities to determine the effects of MHD-EMP and to validate the mitigation methods also are discussed.
Magnetohydrodynamics (MHD) program evaluation
Not Available
1983-05-01
Conclusions and Recommendations: (1) Progress has been made in performance testing of virtually every critical MHD component and subsystem, except for seed regeneration. (2) No insurmountable technical barriers have been identified; however, the component tests have for the most part been of short duration and, in most instances, were conducted under simulated coal-fired conditions. Long duration, coal-fired integrated tests of the MHD power train and of the HRSR subsystem are required to demonstrate system operability and durability. (3) It would appear most appropriate that the first series of complete power train and HRSR tests be conducted at the 50 MW/sub t/ level. The major objectives of these tests should be to verify predicted performance and to show system operability and durability for a period of at least 2000 hours. (4) Assuming successful 50 MW/sub t/ duration tests, a 150 MW/sub t/ completely integrated (topping and bottoming cycles) utility demonstration test is then suggested (3:1 scale-up). (5) The final development step would involve the fabrication of a commercial size plant at a power level of 500 MW/sub t/ or greater. (6) The ultimate adoption of MHD as a means for electric power generation will not be solely determined by its technical performance; the economic climate and projections at the time the technology is mature will strongly influence utility decisions. (7) Estimated capital costs of early commercial MHD plants seem to range from 10% to 30% greater than those for PCF plants with scrubbers. However, because of the higher inherent efficiency of MHD relative to PCF plants (50% vs 35%), the cost of electric power (COE) from an MHD system can nevertheless be competitive for an appropriately broad range of economic scenarios. (8) Finally, it is recognized that a major investment will be necessary to bring the technology to a state of commercial readiness.
Tesche, F.M.; Barnes, P.R.; Meliopoulos, A.P.S.
1992-02-01
This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T&D) systems. This environment, known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), is a very slowly varying electric field induced in the earth`s surface, similar to the field induced by a geomagnetic storm. It can result in the flow of a quasi-dc current in grounded power lines and in the subsequent magnetic saturation of transformers. This saturation, in turn, causes 6-Hz harmonic distortion and an increase in the reactive power required by generation facilities. This report analyzes and discusses these phenomena. The MHD-EMP environment is briefly discussed, and a simplified form of the earth-induced electric field is developed for use in a parametric study of transmission line responses. Various field coupling models are described, and calculated results for the responses of both transmission- and distribution-class power lines are presented. These calculated responses are compared with measurements of transformer operation under dc excitation to infer the MHD-EMP response of these power system components. It is found that the MHD-EMP environment would have a marked effect on a power system by inducing up to several hundreds of amperes of quasi-dc current on power lines. These currents will cause transformers to saturate which could result in excessive harmonic generation, voltage swings, and voltage suppression. The design of critical facilities which are required to operate during and after MHD-EMP events will have to be modified in order to mitigate the effects of these abnormal power system conditions.
Tesche, F.M. , Dallas, TX ); Barnes, P.R. ); Meliopoulos, A.P.S. . Dept. of Electrical Engineering)
1992-02-01
This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T D) systems. This environment, known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), is a very slowly varying electric field induced in the earth's surface, similar to the field induced by a geomagnetic storm. It can result in the flow of a quasi-dc current in grounded power lines and in the subsequent magnetic saturation of transformers. This saturation, in turn, causes 6-Hz harmonic distortion and an increase in the reactive power required by generation facilities. This report analyzes and discusses these phenomena. The MHD-EMP environment is briefly discussed, and a simplified form of the earth-induced electric field is developed for use in a parametric study of transmission line responses. Various field coupling models are described, and calculated results for the responses of both transmission- and distribution-class power lines are presented. These calculated responses are compared with measurements of transformer operation under dc excitation to infer the MHD-EMP response of these power system components. It is found that the MHD-EMP environment would have a marked effect on a power system by inducing up to several hundreds of amperes of quasi-dc current on power lines. These currents will cause transformers to saturate which could result in excessive harmonic generation, voltage swings, and voltage suppression. The design of critical facilities which are required to operate during and after MHD-EMP events will have to be modified in order to mitigate the effects of these abnormal power system conditions.
ERIC Educational Resources Information Center
Kantrowitz, Arthur; Rosa, Richard J.
1975-01-01
Explains the operation of the Magnetohydrodynamic (MHD) generator and advantages of the system over coal, oil or nuclear powered generators. Details the development of MHD generators in the United States and Soviet Union. (CP)
Application of Magnetohydrodynamics (MHD) and Recent Research Trend
NASA Astrophysics Data System (ADS)
Harada, Nobuhiro
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.
NASA Technical Reports Server (NTRS)
Rigo, H. S.; Bercaw, R. W.; Burkhart, J. A.; Mroz, T. S.; Bents, D. J.; Hatch, A. M.
1981-01-01
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.
NASA Technical Reports Server (NTRS)
1981-01-01
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.
NASA Astrophysics Data System (ADS)
1981-09-01
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.
NASA Technical Reports Server (NTRS)
1981-01-01
The estimated plant capital cost for a coal fired 200 MWE electric generating plant with open cycle magnetohydrodynamics is divided into principal accounts based on Federal Energy Regulatory Commision account structure. Each principal account is defined and its estimated cost subdivided into identifiable and major equipment systems. The cost data sources for compiling the estimates, cost parameters, allotments, assumptions, and contingencies, are discussed. Uncertainties associated with developing the costs are quantified to show the confidence level acquired. Guidelines established in preparing the estimated costs are included. Based on an overall milestone schedule related to conventional power plant scheduling experience and starting procurement of MHD components during the preliminary design phase there is a 6 1/2-year construction period. The duration of the project from start to commercial operation is 79 months. The engineering phase of the project is 4 1/2 years; the construction duration following the start of the man power block is 37 months.
NASA Astrophysics Data System (ADS)
1981-09-01
The estimated plant capital cost for a coal fired 200 MWE electric generating plant with open cycle magnetohydrodynamics is divided into principal accounts based on Federal Energy Regulatory Commision account structure. Each principal account is defined and its estimated cost subdivided into identifiable and major equipment systems. The cost data sources for compiling the estimates, cost parameters, allotments, assumptions, and contingencies, are discussed. Uncertainties associated with developing the costs are quantified to show the confidence level acquired. Guidelines established in preparing the estimated costs are included. Based on an overall milestone schedule related to conventional power plant scheduling experience and starting procurement of MHD components during the preliminary design phase there is a 6 1/2-year construction period. The duration of the project from start to commercial operation is 79 months. The engineering phase of the project is 4 1/2 years; the construction duration following the start of the man power block is 37 months.
An innovative demonstration of high power density in a compact MHD (magnetohydrodynamic) generator
Schmidt, H.J.; Lineberry, J.T.; Chapman, J.N.
1990-06-01
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.
Magnetohydrodynamic (MHD) channel corner seal
Spurrier, Francis R. (Pittsburgh, PA)
1980-01-01
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.
MHD (magnetohydrodynamics) program plan, FY88
NASA Astrophysics Data System (ADS)
1988-04-01
The essential elements of the current program, which are based on the June 1984 Coal-Fired Magnetohydrodynamic (MHD) Preliminary Transition and Program Plan, are to: (1) develop technical and environmental data for the integrated MHD topping cycle system through long-term (1000 hours) proof of concept (POC) testing; (2) develop technical and environmental data for the integrated MHD bottoming cycle subsystem through long-term (4000 hours) POC testing; (3) design and construct a seed regeneration system capable of independent operation, using spent seed materials from the MHD process; (4) prepare a conceptual design for an MHD retrofit plant; and (5) continue system studies and supporting research necessary for system testing. Results of the topping cycle POC tests at the Component Development and Integration Facility (CDIF), coupled with the bottoming cycle POC test results obtained at the Coal Fired Flow Facility (CFFF), and the seed regeneration POC effort will provide the critical engineering data base for the private sector's final decision on proceeding with the design, construction, and operation of an MHD retrofit. The development schedule, decision points, and resource requirements are shown.
Not Available
1981-09-01
The reference conceptual design of the 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 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 are presented and the engineering issues that should be reexamined are identified. This report integrates the latest (1980-1981) information from the MHD technology program with the elements of a conventional steam power electric generating plant. It is presented in five volumes.
Diagnostic development and support of MHD (magnetohydrodynamics) test facilities
Not Available
1989-07-01
Mississippi State University (MSU) is developing diagnostic instruments for Magnetohydrodynamics (MHD) power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for HRSR support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with MHD Energy Center computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. MSU personnel will also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs.
Barnes, P.R.; Tesche, F.M.; McConnell, B.W.; Vance, E.F.
1993-09-01
A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth's magnetic field and produces a strong magnetohydrodynamic-electromagnetic pulse (MHD-EMP). MHD-EMP is similar to solar geomagnetic storms in its global and low frequency (less than 1 Hz) nature except that it can be more intense with a shorter duration. It will induce quasi-dc currents in long lines. The MHD-EMP induced currents may cause large voltage fluctuations and severe harmonic distortion in commercial electric power systems. Several MHD-EMP coupling models for predicting the induced current on a wide variety of conducting structures are described, various simulation concepts are summarized, and the results from several MHD-EMP tests are presented. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building, and the commercial power harmonics and voltage swings must be addressed. It is found that facilities can be protected against MHD-EMP by using methods which are consistent with standard engineering practices. MHD-EMP Interaction Analysis, Power Line Model, MHD-EMP Protection Guidelines, Transformer Test.
Magnetohydrodynamic (MHD) driven droplet mixer
Lee, Abraham P.; Lemoff, Asuncion V.; Miles, Robin R.
2004-05-11
A magnetohydrodynamic fluidic system mixes a first substance and a second substance. A first substrate section includes a first flow channel and a first plurality of pairs of spaced electrodes operatively connected to the first flow channel. A second substrate section includes a second flow channel and a second plurality of pairs of spaced electrodes operatively connected to the second flow channel. A third substrate section includes a third flow channel and a third plurality of pairs of spaced electrodes operatively connected to the third flow channel. A magnetic section and a control section are operatively connected to the spaced electrodes. The first substrate section, the second substrate section, the third substrate section, the first plurality of pairs of spaced electrodes, the second plurality of pairs of spaced electrodes, the third plurality of pairs of spaced electrodes, the magnetic section, and the control section are operated to move the first substance through the first flow channel, the second substance through the second flow channel, and both the first substance and the second substance into the third flow channel where they are mixed.
Magnetohydrodynamic (MHD) stretched flow of nanofluid with power-law velocity and chemical reaction
NASA Astrophysics Data System (ADS)
Hayat, Tasawar; Rashid, Madiha; Imtiaz, Maria; Alsaedi, Ahmed
2015-11-01
This paper deals with the boundary layer flow of nanofluid over power-law stretched surface. Analysis has been carried out in the presence of applied magnetic field and chemical reaction. Heat and mass transfer characteristics are studied using heat and mass convective conditions. The governing partial differential equations are transferred to the nonlinear ordinary differential equations. Convergent series solutions are obtained for fluid velocity, temperature and concentrations fields. Influences of pertinent parameters including Hartman number, thermal and concentration Biot numbers and chemical reaction parameters are discussed on the velocity, temperature and concentration profiles. Graphical result are presented and discussed. Computations for local Nusselt and Sherwood numbers are carried out. It is observed that the heat transfer rate is enhanced by increasing power-law index, thermal Biot number and chemical reaction parameter while mass transfer rate increases for power-law index and chemical reaction parameter.
NASA Astrophysics Data System (ADS)
Anderson, Brett; Burstein, Alison; Gentile, Charles
2007-11-01
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.
Not Available
1988-03-15
This progress report of the Space Power MHD System project presents the accomplishments during 1 November 1987 through 31 January 1988. The scope of work covered encompasses the definition of an MHD power system conceptual design and development plan (Task 1). Progress included the following: Subcontracts were issued to the MIT Plasma Fusion Center and the Westinghouse R and D Center. The performance of the 100 MW 500 sec. power system was optimized and the design concept finalized, including mass and energy balances. Mass and cost estimates were prepared. A design review was held at DOE/PETC. This also included the review of the technical issues definition and of the R and D Plan. Following the review, a final iteration on the conceptual design was initiated. Formulation of the R and D Plan was continued. Preparation of the Task 1 R and D Report was initiated. 12 figs.
NASA Technical Reports Server (NTRS)
1981-01-01
Main elements of the design are identified and explained, and the rationale behind them was reviewed. Major systems and plant facilities are listed and discussed. Construction cost and schedule estimates are presented, and the engineering issues that should be reexamined are identified. The latest (1980-1981) information from the MHD technology program is integrated with the elements of a conventional steam power electric generating plant.
NASA Astrophysics Data System (ADS)
1981-09-01
Main elements of the design are identified and explained, and the rationale behind them was reviewed. Major systems and plant facilities are listed and discussed. Construction cost and schedule estimates are presented, and the engineering issues that should be reexamined are identified. The latest (1980-1981) information from the MHD technology program is integrated with the elements of a conventional steam power electric generating plant.
Not Available
1981-09-01
The estimated plant capital cost for a coal fired 200 MWE electric generating plant with open cycle magnetohydrodynamics is divided into principal accounts based on Federal Energy Regulatory Commision account structure. Each principal account is defined and its estimated cost subdivided into identifiable and major equipment systems. The cost data sources for compiling the estimates, cost parameters, allotments, assumptions, and contingencies, are discussed. Uncertainties associated with developing the costs are quantified to show the confidence level acquired. Guidelines established in preparing the estimated costs are included. Based on an overall milestone schedule related to conventional power plant scheduling experience and starting procurement of MHD components during the preliminary design phase there is a 6 1/2-year construction period. The duration of the project from start to commercial operation is 79 months. The engineering phase of the project is 4 1/2 years. The construction duration following the start of the man power block is 37 months.
CosmoMHD: A Cosmological Magnetohydrodynamics Code
NASA Astrophysics Data System (ADS)
Li, Shengtai; Li, Hui; Cen, Renyue
2008-01-01
In this era of precision cosmology, a detailed physical understanding on the evolution of cosmic baryons is required. Cosmic magnetic fields, though still poorly understood, may represent an important component in the global cosmic energy flow that affects the baryon dynamics. We have developed an Eulerian-based cosmological magnetohydrodynamics code (CosmoMHD) with modern shock capturing schemes to study the formation and evolution of cosmic structures in the presence of magnetic fields. We have implemented several high-resolution finite-volume and finite-difference methods for solving the MHD equations with cosmology. The divergence-free condition of the magnetic fields is preserved at a level of computer round-off error via the constraint transport method. We have also implemented a high-resolution method via dual-equation formulation to track the thermal energy of the baryons accurately in very high Mach number or high Alfvén-Mach number regions. Several numerical tests have demonstrated the efficacy of the proposed schemes.
Explosively-driven magnetohydrodynamic (MHD) generator studies
Agee, F.J.; Lehr, F.M.; Vigil, M.; Kaye, R.; Gaudet, J.; Shiffler, D.
1995-08-01
Plasma jet generators have been designed and tested which used an explosive driver and shocktube with a rectangular cross section that optimize the flow velocity and electrical conductivity. The latest in a series of designs has been tested using a reactive load to diagnose the electrical properties of the MHD generator/electromagnet combination. The results of these tests indicate that the plasma jet/MHD generator design does generate a flow velocity greater than 25 km/s and produces several gigawatts of pulsed power in a very small package size. A larger, new generator design is also presented.
MHD (Magnetohydrodynamics) Program Plan, FY 1989
NASA Astrophysics Data System (ADS)
1989-05-01
The essential elements of the current program, which is a continuation of the program outlined in the FY 1988 MHD Program Plan, are to: develop technical and environmental data for the integrated MHD topping cycle system through long-term (1000 hours) proof of concept (POC) testing; develop technical and environmental data for the integrated MHD bottoming cycle subsystem through long-term (4000 hours) POC testing; design and construct a seed regeneration system capable of independent operation, using spent seed materials from the MHD process; prepare a conceptual design for an MHD retrofit plant; and continue system studies and supporting research necessary for system testing. Results of the topping cycle POC tests at the Component Development and Integration Facility (CDIF), coupled with the bottoming cycle POC test results obtained at the Coal Fired Flow Facility (CFFF), and the seed regeneration POC effort will provide the critical engineering data base for the private sector's final decision on proceeding with the design, construction, and operation of an MHD retrofit. The development schedule, decision points, and resource requirements are discussed. As part of the MHD program, international activities of several nations are monitored and evaluated through contact with the international MHD scientific and technical community.
NASA Astrophysics Data System (ADS)
Chaplin, Vernon H.
This thesis describes investigations of two classes of laboratory plasmas with rather different properties: partially ionized low pressure radiofrequency (RF) discharges, and fully ionized high density magnetohydrodynamically (MHD)-driven jets. An RF pre-ionization system was developed to enable neutral gas breakdown at lower pressures and create hotter, faster jets in the Caltech MHD-Driven Jet Experiment. The RF plasma source used a custom pulsed 3 kW 13.56 MHz RF power amplifier that was powered by AA batteries, allowing it to safely float at 4-6 kV with the cathode of the jet experiment. The argon RF discharge equilibrium and transport properties were analyzed, and novel jet dynamics were observed. Although the RF plasma source was conceived as a wave-heated helicon source, scaling measurements and numerical modeling showed that inductive coupling was the dominant energy input mechanism. A one-dimensional time-dependent fluid model was developed to quantitatively explain the expansion of the pre-ionized plasma into the jet experiment chamber. The plasma transitioned from an ionizing phase with depressed neutral emission to a recombining phase with enhanced emission during the course of the experiment, causing fast camera images to be a poor indicator of the density distribution. Under certain conditions, the total visible and infrared brightness and the downstream ion density both increased after the RF power was turned off. The time-dependent emission patterns were used for an indirect measurement of the neutral gas pressure. The low-mass jets formed with the aid of the pre-ionization system were extremely narrow and collimated near the electrodes, with peak density exceeding that of jets created without pre-ionization. The initial neutral gas distribution prior to plasma breakdown was found to be critical in determining the ultimate jet structure. The visible radius of the dense central jet column was several times narrower than the axial current channel radius, suggesting that the outer portion of the jet must have been force free, with the current parallel to the magnetic field. The studies of non-equilibrium flows and plasma self-organization being carried out at Caltech are relevant to astrophysical jets and fusion energy research.
Not Available
1981-09-01
This section contains the estimated plant capital cost for the MHD-ETF. The estimated cost is subdivided into principal accounts, such as Accessory Electrical Systems, based on the conventional Federal Energy Regulatory Commission (FERC) account structure. Definitions for each principal account are provided. The estimated cost in each principal account is further subdivided into identifiable structures and major equipment systems such as, Medium Voltage Equipment. This is the lowest level of cost addressed. However, discussions are provided describing: the cost data sources for compiling the estimates, cost parameters, allotments, assumptions, and contingencies. Uncertainties associated with developing the costs are quantified separately to show the costing confidence level achieved. Appendix 3A provides details of the guidelines established in the preparation of the estimated costs. The appendix contains additional detail, in outline form, defining cost parameter and account contents.
Not Available
1981-09-01
The reference conceptual design of the 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. Detailed system design descriptions are given for the following systems: closed cycle cooling water system, industrial gas systems, fuel oil systems, boiler flue gas system, coal management system, seed management system, slag management system, plant industrial waste system, fire service water system, oxidant supply system, MHD power train, magnet, heat recovery/seed recovery system, inverter, heating, ventilating, and air conditioning system, and electrical system. Engineering drawings are included. (WHK)
NASA Technical Reports Server (NTRS)
1981-01-01
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.
Not Available
1981-09-01
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.
NASA Astrophysics Data System (ADS)
1981-09-01
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.
Multirail electromagnetic launcher powered from a pulsed magnetohydrodynamic generator
NASA Astrophysics Data System (ADS)
Afonin, A. G.; Butov, V. G.; Panchenko, V. P.; Sinyaev, S. V.; Solonenko, V. A.; Shvetsov, G. A.; Yakushev, A. A.
2015-09-01
The operation of an electromagnetic multirail launcher of solids powered from a pulsed magnetohydrodynamic (MHD) generator is studied. The plasma flow in the channel of the pulsed MHD generator and the possibility of launching solids in a rapid-fire mode of launcher operation are considered. It is shown that this mode of launcher operation can be implemented by matching the plasma flow dynamics in the channel of the pulsed MHD generator and the launching conditions. It is also shown that powerful pulsed MHD generators can be used as a source of electrical energy for rapid-fire electromagnetic rail launchers operating in a burst mode.
NASA Technical Reports Server (NTRS)
1981-01-01
The results of magnet system special investigations listed below are summarized: 4 Tesla Magnet Alternate Design Study; 6 Tesla Magnet Manufacturability Study. The conceptual design for a 4 Tesla superconducting magnet system for use with an alternate (supersonic) ETF power train is described, and estimated schedule and cost are identified. The magnet design is scaled from the ETF 6 T Tesla design. Results of a manufacturability study and a revised schedule and cost estimate for the ETF 6 T magnet are reported. Both investigations are extensions of the conceptual design of a 6 T magnet system performed earlier as a part of the overall MED-ETF conceptual design described in Conceptual Design Engineering Report (CDER) Vol. V, System Design Description (SDD) 503 dated September, 1981, DOE/NASA/0224-1; NASA CR-165/52.
A nuclear powered space based multimegawatt MHD disc power system
NASA Astrophysics Data System (ADS)
Holman, Robert R.; Lance, Joseph R.; Vanbibber, Lawrence E.; Louis, Jean F.
A very compact space based magnetohydrodynamic (MHD) power system capable of meeting space platform burst power needs is examined. An open cycle MHD disc generator concept has been incorporated in a nuclear power system arrangement. Thermal energy for the system is provided by a NERVA derivative nuclear reactor and the MHD disc generator is used for thermal to electric energy conversion. Study results show to date that the NERVA derivative reactor coupled with the MHD disc generator provides a low total system launch mass and a very high energy extraction of greater than 20 MJ/kg in power operation. This energy extraction is much higher than the less than 2.5 MJ/kg values of linear MHD generator systems studied previously.
Not Available
1981-09-01
This report summarizes the reference conceptual design of the MHD Engineering Test Facility (ETF), a prototype 200 MWe coal-fired electric generating plant designed to demonstrate the commercial feasibility of open cycle MHD. 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. The report also presents construction cost and schedule estimates, and identifies the engineering issues that should be reexamined. This report integrates the latest (1980-1981) information from the MHD technology program with the elements of a conventional steam power electric generating plant. The engineering information (volume II) is presented, and volume III (costs and schedules) is included as microfiche.
Investigation of a liquid-metal magnetohydrodynamic power system.
NASA Technical Reports Server (NTRS)
Elliott, D. G.; Hays, L. G.; Cerini, D. J.; Bogdanoff, D. W.
1972-01-01
Liquid-metal magnetohydrodynamic power conversion is being investigated for nuclear-electric propulsion. A liquid-metal MHD converter has no moving mechanical parts and requires a heat source temperature of only 1300 K. Cycle efficiencies of 5% to 8% for single-stage converters and 10% for multistage converters appear attainable. The specific weight of a 240 kWe MHD power plant has been estimated as 30 kg/kWe with shielding for unmanned science missions.
Not Available
1981-09-01
Main elements of the design are identified and explained, and the rationale behind them was reviewed. Major systems and plant facilities are listed and discussed. Construction cost and schedule estimates are presented, and the engineering issues that should be reexamined are identified. The latest (1980-1981) information from the MHD technology program is integrated with the elements of a conventional steam power electric generating plant.
NASA Technical Reports Server (NTRS)
Tsu, T. C.
1976-01-01
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.
NASA Technical Reports Server (NTRS)
Hoover, D. Q.
1976-01-01
Electric power plant costs and efficiencies are presented for three basic open-cycle MHD systems: (1) direct coal fired system, (2) a system with a separately fired air heater, and (3) a system burning low-Btu gas from an integrated gasifier. Power plant designs were developed corresponding to the basic cases with variation of major parameters for which major system components were sized and costed. Flow diagrams describing each design are presented. A discussion of the limitations of each design is made within the framework of the assumptions made.
Pulse Detonation Rocket Magnetohydrodynamic Power Experiment
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Jones, J. E.; Dobson, C. C.; Cole, J. W.; Thompson, B. R.; Plemmons, D. H.; Turner, M. W.
2003-01-01
The production of onboard electrical power by pulse detonation engines is problematic in that they generate no shaft power; however, pulse detonation driven magnetohydrodynamic (MHD) power generation represents one intriguing possibility for attaining self-sustained engine operation and generating large quantities of burst power for onboard electrical systems. To examine this possibility further, a simple heat-sink apparatus was developed for experimentally investigating pulse detonation driven MHD generator concepts. The hydrogen oxygen fired driver was a 90 cm long stainless steel tube having a 4.5 cm square internal cross section and a short Schelkin spiral near the head end to promote rapid formation of a detonation wave. The tube was intermittently filled to atmospheric pressure and seeded with a CsOH/methanol prior to ignition by electrical spark. The driver exhausted through an aluminum nozzle having an area contraction ratio of A*/A(sub zeta) = 1/10 and an area expansion ratio of A(sub zeta)/A* = 3.2 (as limited by available magnet bore size). The nozzle exhausted through a 24-electrode segmented Faraday channel (30.5 cm active length), which was inserted into a 0.6 T permanent magnet assembly. Initial experiments verified proper drive operation with and without the nozzle attachment, and head end pressure and time resolved thrust measurements were acquired. The exhaust jet from the nozzle was interrogated using a polychromatic microwave interferometer yielding an electron number density on the order of 10(exp 12)/cm at the generator entrance. In this case, MHD power generation experiments suffered from severe near-electrode voltage drops and low MHD interaction; i.e., low flow velocity, due to an inherent physical constraint on expansion with the available magnet. Increased scaling, improved seeding techniques, higher magnetic fields, and higher expansion ratios are expected to greatly improve performance.
High-. beta. operation and MHD (magnetohydrodynamic) activity on TFTR
McGuire, K.
1990-04-01
Magnetohydrodynamic (MHD) activity within three zones (core, half- radius, and edge) of TFTR (Plasma Physics and Controlled Nuclear Fusion Research (1986), (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 of the q profile. Near the half-radius the m/n = 3/2 and 2/1 resistive ballooning modes are found to correlate with a beta collapse. The pressure and the pressure gradient at the mode rational surface are found to play an important role in stability. MHD activity is also studied at the plasma edge during limiter H-modes. The Edge Localized Mode (ELMs) are found to have a precursor mode with a frequency between 50--200 kHz and a mode number m/n = 1/0. The mode does not show a ballooning structure. While these instabilities have been studied on many other machines, on TFTR the studies have been extended to high pressure (plasma pressure greater than 4 {times} 10{sup 5} Pa) and low collisionality. 16 refs., 3 figs.
The optimization air separation plants for combined cycle MHD-power plant applications
NASA Technical Reports Server (NTRS)
Juhasz, A. J.; Springmann, H.; Greenberg, R.
1980-01-01
Some of the design approaches being employed during a current supported study directed at developing an improved air separation process for the production of oxygen enriched air for magnetohydrodynamics (MHD) combustion are outlined. The ultimate objective is to arrive at conceptual designs of air separation plants, optimized for minimum specific power consumption and capital investment costs, for integration with MHD combined cycle power plants.
NASA Technical Reports Server (NTRS)
Han, S. M.; Wu, S. T.; Nakagawa, Y.
1982-01-01
Radial propagation of one-dimensional magnetohydrodynamic (MHD) waves are analyzed numerically on the basis of the Implicit-Continuous-Fluid-Eulerian (ICE) scheme. Accuracy of the numerical method and other properties are tested through the study of MHD wave propagation. The three different modes of MHD waves (i.e., fast-, slow- and Alfven (transverse) mode) are generated by applying physically consistent boundary perturbations derived from MHD compatibility relations. It is shown that the resulting flow following these waves depend upon the relative configurations of the initial magnetic field and boundary perturbations.
Ways to improve MHD power plants and prospects of their application
NASA Astrophysics Data System (ADS)
Batenin, V. M.; Pistchikov, S. I.; Sokolov, J. N.; Shelkov, E. M.
1991-05-01
The characteristics of magnetohydrodynamic (MHD) power plants, their modification possibilities, and their areas of application are analyzed. The analysis is based on the status of available power plants including steam turbine and combined-cycle steam/gas power plants. Conventional MHD power plants, based on existing technical solutions and various novel schemes are discussed. The main directions for improvement of energy conversion efficiency are presented, together with ways to modify MHD systems so as to reduce their capital costs. The conclusion is that MHD power plants could be competitive with most advanced power generation technologies.
Magnetohydrodynamic Power Generation in the Laboratory Simulated Martian Entry Plasma
NASA Technical Reports Server (NTRS)
Vuskovic, L.; Popovic, S.; Drake, J.; Moses, R. W.
2005-01-01
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.
Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Lyles, Garry M. (Technical Monitor)
2001-01-01
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).
Laser-powered MHD generators for space application
NASA Technical Reports Server (NTRS)
Jalufka, N. W.
1986-01-01
Magnetohydrodynamic (MHD) energy conversion systems of the pulsed laser-supported detonation (LSD) wave, plasma MHD, and liquid-metal MHD (LMMHD) types are assessed for their potential as space-based laser-to-electrical power converters. These systems offer several advantages as energy converters relative to the present chemical, nuclear, and solar devices, including high conversion efficiency, simple design, high-temperature operation, high power density, and high reliability. Of these systems, the Brayton cycle liquid-metal MHD system appears to be the most attractive. The LMMHD technology base is well established for terrestrial applications, particularly with regard to the generator, mixer, and other system components. However, further research is required to extend this technology base to space applications and to establish the technology required to couple the laser energy into the system most efficiently. Continued research on each of the three system types is recommended.
Nuclear reactor magnetohydrodynamic power generator for directed energy weapons
NASA Astrophysics Data System (ADS)
Swallom, Daniel W.
The SDI electrical power requirements for directed energy weapons (DEW) may range from tens of megawatts to over hundreds of megawatts. For this application, where the power requirement is continuous for a period to time ranging from tens to hundreds or thousands of seconds, nuclear magnetohydrodynamic (MHD) power generation provides an attractive method for producing the required power levels. The MHD power system offers the advantages of simplicity of operation because of no moving or rotational parts; no upper limit on gas inlet temperature, which is a restriction in the case of rotating machinery; an upper limit on current output, which prevents the output current from exceeding twice the nominal current; and favorable scaling to larger size systems.
Not Available
1987-06-01
This report presents a study of the nuclear weapons magnetohydrodynamic (MHD) effects on submarine communications cables. The study consisted of the analysis and interpretation of currently available data on submarine cable systems TAT-4, TAT-6, and TAT-7. The primary result of the study is that decrease of the effective resistivity with frequency over the available experimental range, coupled with the model results, leads to quite small effective resistivities at the MHD characteristic frequencies, and hence small earth potential differences. Thus, it appears that submarine cable systems are less susceptible to an MHD threat than their land-based counter-parts.
NASA Astrophysics Data System (ADS)
Priest, E.; Forbes, T.; Murdin, P.
2000-11-01
Magnetohydrodynamics (or MHD for short) is the study of the interaction between a magnetic field and a plasma treated as a continuous medium (e.g. Cowling 1957, Roberts 1967, Priest 1982, 1994). Most of the universe is not a normal gas but is instead a plasma. We are all familiar on Earth with the three states of matter (solid, liquid and gas). You change from one state to another (such as ice to...
Development of materials for open-cycle magnetohydrodynamics (MHD): ceramic electrode. Final report
Bates, J.L.; Marchant, D.D.
1986-09-01
Pacific Northwest Laboratory, supported by the US Department of Energy, developed advanced materials for use in open-cycle, closed cycle magnetohydrodynamics (MHD) power generation, an advanced energy conversion system in which the flow of electrically conducting fluid interacts with an electric field to convert the energy directly into electricity. The purpose of the PNL work was to develop electrodes for the MHD channel. Such electrodes must have: (1) electrical conductivity above 0.01 (ohm-cm)/sup -1/ from near room temperature to 1900/sup 0/K, (2) resistance to both electrochemical and chemical corrosion by both slag and potassium seed, (3) resistance to erosion by high-velocity gases and particles, (4) resistance to thermal shock, (5) adequate thermal conductivity, (6) compatibility with other channel components, particularly the electrical insulators, (7) oxidation-reduction stability, and (8) adequate thermionic emission. This report describes the concept and development of high-temperature, graded ceramic composite electrode materials and their electrical and structural properties. 47 refs., 16 figs., 13 tabs.
Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power
NASA Technical Reports Server (NTRS)
Litchford, Ron J.
2001-01-01
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).
FLIP MHD - A particle-in-cell method for magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Brackbill, J. U.
1991-01-01
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.
NASA Technical Reports Server (NTRS)
Holman, R. R.; Lippert, T. E.
1976-01-01
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.
MHD channel performance for potential early commercial MHD power plants
NASA Technical Reports Server (NTRS)
Swallom, D. W.
1981-01-01
The commercial viability of full and part load early commercial MHD power plants is examined. The load conditions comprise a mass flow of 472 kg/sec in the channel, Rosebud coal, 34% by volume oxygen in the oxidizer preheated to 922 K, and a one percent by mass seeding with K. The full load condition is discussed in terms of a combined cycle plant with optimized electrical output by the MHD channel. Various electrical load parameters, pressure ratios, and magnetic field profiles are considered for a baseload MHD generator, with a finding that a decelerating flow rate yields slightly higher electrical output than a constant flow rate. Nominal and part load conditions are explored, with a reduced gas mass flow rate and an enriched oxygen content. An enthalpy extraction of 24.6% and an isentropic efficiency of 74.2% is predicted for nominal operation of a 526 MWe MHD generator, with higher efficiencies for part load operation.
Power Requirement for Nonequilibrium MHD-Bypass Scramjet
NASA Technical Reports Server (NTRS)
Park, Chul; Bogdanoff, David W.; Mehta, Unmeel
2000-01-01
It has been suggested previously that the performance of scramjet propulsion system may be improved by the use of magnetohydrodynamic (MHD) energy bypass: an MHD generator could be made to decelerate the flow entering the combustor, thereby improving combustion efficiency, and the electrical power generated could be made to accelerate the flow exiting from the combustor prior to expanding through the nozzle. In one of such proposed schemes, the MHD generator is proposed to be operated at a low temperature and ionization is to be achieved under nonequilibrium by the application of an external power. In the present work, the required power of such an external source is calculated assuming a 100%-efficient nonequilibrium ionization scheme. The power required is that needed to prevent the degree of ionization from reaching equilibrium with the low gas temperature. The flow is seeded with potassium or cesium. Specific impulse is calculated with and without turbulent friction. The results show that, for typical intended flight conditions, the specific impulse obtained is substantially higher than that of a typical scramjet, but the required external-power is several times that of the power generated in the MHD generator.
NASA Technical Reports Server (NTRS)
Benyo, Theresa L.
2010-01-01
This paper describes the preliminary results of a thermodynamic cycle analysis of a supersonic turbojet engine with a magnetohydrodynamic (MHD) energy bypass system that explores a wide range of MHD enthalpy extraction parameters. Through the analysis described here, it is shown that applying a magnetic field to a flow path in the Mach 2.0 to 3.5 range can increase the specific thrust of the turbojet engine up to as much as 420 N/(kg/s) provided that the magnitude of the magnetic field is in the range of 1 to 5 Tesla. The MHD energy bypass can also increase the operating Mach number range for a supersonic turbojet engine into the hypersonic flight regime. In this case, the Mach number range is shown to be extended to Mach 7.0.
MHD (magnetohydrodynamic) undersea propulsion: A novel concept with renewed interest
Doss, E.D.; Geyer, H.K. ); Roy, G.D. )
1990-01-01
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.
WhiskyMHD: Numerical Code for General Relativistic Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Baiotti, Luca; Giacomazzo, Bruno; Hawke, Ian; et al.
2010-10-01
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.
Pulse Detonation Rocket MHD Power Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Cook, Stephen (Technical Monitor)
2002-01-01
A pulse detonation research engine (MSFC (Marshall Space Flight Center) Model PDRE (Pulse Detonation Rocket Engine) G-2) has been developed for the purpose of examining integrated propulsion and magnetohydrodynamic power generation applications. The engine is based on a rectangular cross-section tube coupled to a converging-diverging nozzle, which is in turn attached to a segmented Faraday channel. As part of the shakedown testing activity, the pressure wave was interrogated along the length of the engine while running on hydrogen/oxygen propellants. Rapid transition to detonation wave propagation was insured through the use of a short Schelkin spiral near the head of the engine. The measured detonation wave velocities were in excess of 2500 m/s in agreement with the theoretical C-J velocity. The engine was first tested in a straight tube configuration without a nozzle, and the time resolved thrust was measured simultaneously with the head-end pressure. Similar measurements were made with the converging-diverging nozzle attached. The time correlation of the thrust and head-end pressure data was found to be excellent. The major purpose of the converging-diverging nozzle was to configure the engine for driving an MHD generator for the direct production of electrical power. Additional tests were therefore necessary in which seed (cesium-hydroxide dissolved in methanol) was directly injected into the engine as a spray. The exhaust plume was then interrogated with a microwave interferometer in an attempt to characterize the plasma conditions, and emission spectroscopy measurements were also acquired. Data reduction efforts indicate that the plasma exhaust is very highly ionized, although there is some uncertainty at this time as to the relative abundance of negative OH ions. The emission spectroscopy data provided some indication of the species in the exhaust as well as a measurement of temperature. A 24-electrode-pair segmented Faraday channel and 0.6 Tesla permanent magnet assembly were then installed on Marshall Space Flight Center's (MSFC's) rectangular channel pulse detonation research engine. Magnetohydrodynamic (MHD) electrical power extraction experiments were carried out for a range of load impedances in which cesium hydroxide seed (dissolved in methanol) was sprayed into the gaseous oxygen/hydrogen propellants. Positive power extraction was obtained, but preliminary analysis of the data indicated that the plasma electrical conductivity is lower than anticipated and the near-electrode voltage drop is not negligible. It is believed that the electrical conductivity is reduced due to a large population of negative OH ions. This occurs because OH has a strong affinity for capturing free electrons. The effect of near-electrode voltage drop is associated with the high surface-to-volume ratio of the channel (1-inch by 1-inch cross-section) where surface effects play a dominant role. As usual for MHD devices, higher performance will require larger scale devices. Overall, the gathered data is extremely valuable from the standpoint of understanding plasma behavior and for developing empirical scaling laws.
Two-dimensional magnetohydrodynamic simulations of poloidal flows in tokamaks and MHD pedestal
Guazzotto, L.; Betti, R.
2011-09-15
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.
Substorm features in MHD (magnetohydrodynamics) simulations of magnetotail dynamics
Birn, J.; Hesse, M.
1990-01-01
We present a review and extended analysis of characteristic results from our nonideal three-dimensional MHD simulations of unstable magnetotail evolution, which develops without the necessity of external driving or prescribed localization on nonideal effects. These modes involve magnetic reconnection at a near-Earth site in the tail, consistent with the near-Earth neutral line model of substorms. The evolution tailward of the reconnection site is characterized by plasmoid formation and ejection into the far tail, plasma sheet thinning between the near-Earth neutral line (X line) and the departing plasmoid, and fast tailward flow, which occupies large sections of the plasma sheet at larger distance from the X line, while it occurs only in very limited space and time sections close to the X line. The region earthward of the X line is characterized by dipolarization, propagating from midnight toward the flank regions and, perhaps, tailward. It is associated with the signatures of the substorm current wedge: reduction and diversion of cross-tail current from a region surrounding the reconnection site and increase of Region 1 type field-aligned currents. A mapping of these currents to the Earth on the basis of an empirical magnetic field model shows good agreement of the mapped current system with the observed Region 1 field-aligned current system and its substorm associated changes, including also a nightward and equatorward shift of the peaks of the field-aligned current density. The evolution of the mappings of the boundaries of the closed field line region bears strong resemblance to the formation and expansion of he auroral bulge. The consistency of all of these details with observed substorm features strongly supports the idea that substorm evolution in the tail is that of a large scale nonideal instability.
Rapporteur report: MHD electric power plants
NASA Technical Reports Server (NTRS)
Seikel, G. R.
1980-01-01
Five US papers from the Proceedings of the Seventh International Conference on MHD Electrical Power Generation at the Massachusetts Institute of Technology are summarized. Results of the initial parametric phase of the US effort on the study of potential early commercial MHD plants are reported and aspects of the smaller commercial prototype plant termed the Engineering Test Facility are discussed. The alternative of using a disk geometry generator rather than a linear generator in baseload MHD plants is examined. Closed-cycle as well as open-cycle MHD plants are considered.
Coal-gasification/MHD/steam-turbine combined-cycle (GMS) power generation
Lytle, J.M.; Marchant, D.D.
1980-11-01
The coal-gasification/MHD/steam-turbine combined cycle (GMS) refers to magnetohydrodynamic (MHD) systems in which coal gasification is used to supply a clean fuel (free of mineral matter and sulfur) for combustion in an MHD electrical power plant. Advantages of a clean-fuel system include the elimination of mineral matter or slag from all components other than the coal gasifier and gas cleanup system; reduced wear and corrosion on components; and increased seed recovery resulting from reduced exposure of seed to mineral matter or slag. Efficiencies in some specific GMS power plants are shown to be higher than for a comparably sized coal-burning MHD power plant. The use of energy from the MHD exhaust gas to gasify coal (rather than the typical approach of burning part of the coal) results in these higher efficiencies.
MHD-EMP interaction with power transmission and distribution systems
Tesche, F.M.; Barnes, P.R.
1991-12-01
A nuclear detonation at altitudes of several hundred kilometers above the earth will distort the earth`s magnetic field and results in a time-variation of the geomagnetic field on the earth`s surface. This magnetic field interacts with the finitely conducting earth to produce a time varying electric field, also on the earth`s surface. Known at the magnetohydrodynamic electromagnetic pulse (MHD-EMP), this resulting E-field can induce a net voltage in long electrical conductors, such as power transmission lines. If these conductors are electrically connected to the earth at both ends, a current can be induced to flow in the conductors, and this can cause damage or upset to certain electrical systems. This paper presents the results of a study on the interaction of the MHD-EMP with power transmission and distribution (T&D) systems. A brief overview of the MHD-EMP environment used in the study is presented, and the analytical models used for estimating the coupling of this environment to T&D lines are discussed. Because of the quasi-static nature of MHD-EMP, the models are essentially simple DC circuit models. However, complications arise in attempting to treat realistic line configurations having a large number of support towers and an overhead shield or neutral wires. There models are discussed in detail. 3 refs., 5 figs., 1 tab.
Solar driven liquid metal MHD power generator
Lee, J.H.; Hohl, F.
1981-05-01
A method for solar electric power generation in space is described. 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. NASA
Solar driven liquid metal mhd power generator
Hohl, F.; Lee, J.H.
1983-06-14
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.
Solar driven liquid metal MHD power generator
NASA Technical Reports Server (NTRS)
Lee, J. H.; Hohl, F. (inventors)
1983-01-01
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.
NASA Astrophysics Data System (ADS)
Majid, M. F. M. A.; Apandi, Muhamad Al-Hakim Md; Sabri, M.; Shahril, K.
2016-02-01
As increasing of agricultural and industrial activities each year has led to an increasing in demand for energy. Possibility in the future, the country was not able to offer a lot of energy and power demand. This means that we need to focus on renewable energy to supply the demand for energy. Energy harvesting is among a method that can contribute on the renewable energy. MHD power generator is a new way to harvest the energy especially Ocean wave energy. An experimental investigation was conducted to explore performance of MHD generator. The effect of intensity of NaCl Solution (Sea Water), flow rate of NaCl solution, magnetic strength and magnet position to the current produce was analyzed. The result shows that each factor is give a significant effect to the current produce, because of that each factor need to consider on develop of MHD generator to harvest the wave energy as an alternative way to support the demand for energy.
Chatterjee, Dipankar; Amiroudine, Sakir
2011-02-01
A comprehensive non-isothermal Lattice Boltzmann (LB) algorithm is proposed in this article to simulate the thermofluidic transport phenomena encountered in a direct-current (DC) magnetohydrodynamic (MHD) micropump. Inside the pump, an electrically conducting fluid is transported through the microchannel by the action of an electromagnetic Lorentz force evolved out as a consequence of the interaction between applied electric and magnetic fields. The fluid flow and thermal characteristics of the MHD micropump depend on several factors such as the channel geometry, electromagnetic field strength and electrical property of the conducting fluid. An involved analysis is carried out following the LB technique to understand the significant influences of the aforementioned controlling parameters on the overall transport phenomena. In the LB framework, the hydrodynamics is simulated by a distribution function, which obeys a single scalar kinetic equation associated with an externally imposed electromagnetic force field. The thermal history is monitored by a separate temperature distribution function through another scalar kinetic equation incorporating the Joule heating effect. Agreement with analytical, experimental and other available numerical results is found to be quantitative. PMID:21053082
NASA Astrophysics Data System (ADS)
Das, Subrat; Brooks, Geoffrey; Morsi, Yos
2011-02-01
A mathematical model of magnetohydrodynamic (MHD) effects in an aluminum reduction cell using numerical approximation of a finite element method is presented. In this numerical model, the magnetic field resulting from the cell cathode bus as well as the magnetic field from both downstream and upstream cells are included. The article outlines the three-dimensional simulation of Lorentz force distribution that results from current distribution in both the cathode bus and the cell linings. These forces are important in the side channel of the cell as the current changes its direction because of an inclined sidewall design. Thus, the present work has two main features, which are (1) a numerical model to predict Lorentz field distribution in the electrolytic cell and (2) the influence of sidewall design on current distribution in the side channel and MHD forces. The model predicts that the magnitude of Lorentz force is at its maximum near the sidewall ( i.e., along the side channel). The radial component of the Lorentz force creates a concentric rotational flow field, whereas the radial component is responsible for the metal "heave." Results are obtained for different inclination angles ( ? = 50 to 64 deg) of the sidewall insulation and at different pot-line currents (140 kA to 180 kA). The direction of the resultant Lorentz force is greatly influenced by the slope of the sidewall and is important to the convective flow of metal and bath in the cell.
Off-design study of an open cycle MHD power plant with oxygen enrichment
NASA Astrophysics Data System (ADS)
Geyer, H. K.; Berry, G. F.
1981-01-01
Some of the more important aspects of off-design operation for a magnetohydrodynamic (MHD) power plant are discussed. It is noted that the plant must be designed to meet part-load and overload conditions and that the optimal design should be subject to a specified load demand curve. An analysis is made for off-design regimes to determine the compatible joint operating conditions for an MHD topping cycle, a steam bottoming plant, a turbine train, a compressor, and an oxygen separation plant. The analysis is subject to such constraints as metal temperatures, second law violations, component performance requirements, and environmental considerations.
Legro, J.R.; Abi-Samra, N.C.; Tesche, F.M.
1985-05-01
In addition to the initial transients designated as fast transient high-altitude EMP (HEMP) and intermediate time EMP, electromagnetic signals are also perceived at times from seconds to hundreds of seconds after a high-altitude nuclear burst. This signal has been defined by the term magnetohydrodynamic-electromagnetic pulse (MHD-EMP). The MHD-EMP phenomena has been both detected in actual weapon tests and predicted from theoretical models. This volume documents a preliminary research effort to investigate the nature and coupling of the MHD-EMP environments to electric power systems, define the construction of approximate system response network models, and document the development of a unified methodology to assess equipment and systematic vulnerability. The MHD-EMP environment is compared to a qualitatively similar natural event, the electromagnetic environment produced by geomagnetic storms.
Chang, S.L.; Lottes, S.A.; Bouillard, J.X.; Petrick, M.
1997-11-01
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.
Jones, A.R.
1985-08-01
This System Design Description and Specification provides the basis for the design of the magnetohydrodynamic (MHD) Power Train (PT) for a nominal 200 MWe early commercial tiHD/Steam Power Plant. This document has been developed under Task 2, Conceptual Design, of Contract DE-AC22-83PC60575 and is to be used by the project as the controlling and coordinating documentation during future design efforts. Modification and revision of this specification will occur as the design matures, and tiie-Westinghouse MHD Project Manager will be the focal point for maintaining this document and issuing periodic revisions. This document is intended to delineate the power train and-power train components requirements and assumptions that properly reflect the MHD/Steam Power Plant in the PT design. The parameters discussed in this document have been established through system calculations as well as through constraints set by technology and by limitations on materials, cost, physical processes associated with MHD, and the expected operating data for the plant. The specifications listed in this document have precedence over all referenced documents. Where this specification appears to conflict with the requirements of a reference document, such conflicts should be brought to the attention of the Westinghouse MHD Project Manager for resolution.
Micro optical fiber display switch based on the magnetohydrodynamic (MHD) principle
NASA Astrophysics Data System (ADS)
Lian, Kun; Heng, Khee-Hang
2001-09-01
This paper reports on a research effort to design, microfabricate and test an optical fiber display switch based on magneto hydrodynamic (MHD) principal. The switch is driven by the Lorentz force and can be used to turn on/off the light. The SU-8 photoresist and UV light source were used for prototype fabrication in order to lower the cost. With a magnetic field supplied by an external permanent magnet, and a plus electrical current supplied across the two inert sidewall electrodes, the distributed body force generated will produce a pressure difference on the fluid mercury in the switch chamber. By change the direction of current flow, the mercury can turn on or cut off the light pass in less than 10 ms. The major advantages of a MHD-based micro-switch are that it does not contain any solid moving parts and power consumption is much smaller comparing to the relay type switches. This switch can be manufactured by molding gin batch production and may have potential applications in extremely bright traffic control,, high intensity advertising display, and communication.
NASA Astrophysics Data System (ADS)
Lorzel, Heath; Mikellides, Pavlos G.
2011-05-01
The time-dependent, 2[1/2]-dimensional, axisymmetric, magnetohydrodynamics (MHD) solver, MACH2 has been upgraded to include the effects of nonequilibrium air chemistry in order to properly model weakly ionized flows over high-speed vehicles. The thermochemical model was subjected to several validation cases such as comparisons to the experimentally deduced shock stand-off distance of nitrogen flow over spheres, the shock stand-off distance of spheres fired into air in a ballistic test facility, and the electron number density on the surface of the Ram-C re-entry experiment. Furthermore, the magnetic induction equation has been upgraded with new verified models that compute the Hall effect, ion slip terms, and an applied axial electric field. Finally, simulations of an idealized MHD electrical power generator are compared with existing analytic solutions, demonstrating the applicability of the improved numerical code to model, analyze and design MHD power generators onboard high-speed vehicles.
NASA Astrophysics Data System (ADS)
Benyo, Theresa Louise
Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program. One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the exhaust flow from the engine by converting electrical current back into flow enthalpy to increase thrust. Though there has been considerable research into the use of MHD generators to produce electricity for industrial power plants, interest in the technology for flight-weight aerospace applications has developed only recently. In this research, electromagnetic fields coupled with weakly ionzed gases to slow hypersonic airflow were investigated within the confines of an MHD energy-bypass system with the goal of showing that it is possible for an air-breathing engine to transition from takeoff to Mach 7 without carrying a rocket propulsion system along with it. The MHD energy-bypass system was modeled for use on a supersonic turbojet engine. The model included all components envisioned for an MHD energy-bypass system; two preionizers, an MHD generator, and an MHD accelerator. A thermodynamic cycle analysis of the hypothesized MHD energy-bypass system on an existing supersonic turbojet engine was completed. In addition, a detailed thermodynamic, plasmadynamic, and electromagnetic analysis was combined to offer a single, comprehensive model to describe more fully the proper plasma flows and magnetic fields required for successful operation of the MHD energy bypass system. The unique contribution of this research involved modeling the current density, temperature, velocity, pressure, electric field, Hall parameter, and electrical power throughout an annular MHD generator and an annular MHD accelerator taking into account an external magnetic field within a moving flow field, collisions of electrons with neutral particles in an ionized flow field, and collisions of ions with neutral particles in an ionized flow field (ion slip). In previous research, the ion slip term has not been considered. The MHD energy-bypass system model showed that it is possible to expand the operating range of a supersonic jet engine from a maximum of Mach 3.5 to a maximum of Mach 7. The inclusion of ion slip within the analysis further showed that it is possible to 'drive' this system with maximum magnetic fields of 3 T and with maximum conductivity levels of 11 mhos/m. These operating parameters better the previous findings of 5 T and 10 mhos/m, and reveal that taking into account collisions between ions and neutral particles within a weakly ionized flow provides a more realistic model with added benefits of lower magnetic fields and conductivity levels especially at the higher Mach numbers. (Abstract shortened by UMI.).
Radiation-driven MHD systems for space applications
NASA Technical Reports Server (NTRS)
Lee, J. H.; Jalufka, N. W.
1982-01-01
High-power radiation such as concentrated solar or high-power laser radiation is considered as a driver for magnetohydrodynamic (MHD) systems which could be developed for efficient power generation and propulsion in space. Eight different systems are conceivable since the MHD systems can be classified in two: plasma and liquid-metal MHD's. Each of these systems is reviewed and solar- (or laser-) driven MHD thrusters are proposed.
Radiation-driven MHD systems for space applications
NASA Astrophysics Data System (ADS)
Lee, J. H.; Jalufka, N. W.
High-power radiation such as concentrated solar or high-power laser radiation is considered as a driver for magnetohydrodynamic (MHD) systems which could be developed for efficient power generation and propulsion in space. Eight different systems are conceivable since the MHD systems can be classified in two: plasma and liquid-metal MHD's. Each of these systems is reviewed and solar- (or laser-) driven MHD thrusters are proposed.
NASA Astrophysics Data System (ADS)
Akbar, Tanvir; Nawaz, Rab; Kamran, Muhammad; Rasheed, Amer
2015-11-01
Steady and unsteady flow of a second grade MHD fluid in a porous medium with Hall current effects is studied. Assuming an priori known vorticity proportional to the stream function up to an additive uniform stream, exact solutions for velocity field are obtained corresponding to different choices of pertinent flow parameters. Graphical results are presented to depict the influence of pertinent flow parameters on the considered MHD flow.
MHD (magnetohydrodynamics) channel development: Quarterly report for January 1987-March 1987
Not Available
1987-04-01
During the report period several slag doping tests were performed. Four of these tests are described in this report. The results were generally encouraging. Four dopants were investigated: Fe/sub 2/O/sub 3/, Fe/sub 3/O/sub 4/, MnO, and CrO/sub 2/. All but the CrO/sub 2/ proved effective within some range of dopant flow rate. At flow rates above or below this range none of the dopants were desirable. The proper ranges for each of the dopants was coarsely mapped in these experiments. When the dopants were injected directly on the anode wall a power increase was observed. This indicates a possible reduction in the voltage drop due to the presence of the dopant. No power gain or loss was observed when the dopant was injected on the cathode wall. However, inter-cathode voltages were observed to spread more uniformly along the wall. High voltages decreased and low voltages increased. This result should help to reduce wear on the cathodes and their neighboring wall elements by reducing the local electrical field. Current control circuits were tested on both MK VI and MK VII type generators and components for consolidation circuits ordered. Solutions to waste disposal problems created by the implementation of new environmental regulations are being investigated. The MHD generator data from the CDIF 87-SEED-1, 87-SEED-2, and 87-SEED-3 tests have been analyzed and the results are presented in this report. The results of the SIDA model presented in this quarterly report are obtained by assuming a constant boundary layer voltage drop. Variations in the boundary layer voltage drop as a result of diagonal loading changes, iron oxide addition, or seeding rates changes were not considered. Corrections for the effects of ..delta..V/sub b1/ will be made to the results of SIDA when the voltage drop measurements become available.
NASA Technical Reports Server (NTRS)
Wu, S. T.
1987-01-01
Theoretical and numerical modeling of solar activity and its effects on the solar atmosphere within the context of magnetohydrodynamics were examined. Specifically, the scientific objectives were concerned with the physical mechanisms for the flare energy build-up and subsequent release. In addition, transport of this energy to the corona and solar wind was also investigated. Well-posed, physically self-consistent, numerical simulation models that are based upon magnetohydrodynamics were sought. A systematic investigation of the basic processes that determine the macroscopic dynamic behavior of solar and heliospheric phenomena was conducted. A total of twenty-three articles were accepted and published in major journals. The major achievements are summarized.
Simulation of two-dimensional fully developed laminar flow for a magneto-hydrodynamic (MHD) pump.
Wang, Pei-Jen; Chang, Chia-Yuan; Chang, Ming-Lang
2004-07-30
MHD micro-pumps circumvent the wear and fatigue caused by high pressure-drop across the check valves of mechanical micro-pumps in micro-fluidic systems. Early analyses of the fluid flow for MHD micro-pumps were mostly made possible by the Poiseuille flow theory; however, this conventional laminar approach cannot illustrate the effects of various channel sizes and shapes. This paper, therefore, presents a simplified MHD flow model based upon steady state, incompressible and fully developed laminar flow theory to investigate the characteristics of a MHD pump. Inside the pump, flowing along the channel is the electrically conducting fluid flowing driven by the Lorentz forces in the direction perpendicular to both dc magnetic field and applied electric currents. The Lorentz forces were converted into a hydrostatic pressure gradient in the momentum equations of the MHD channel flow model. The numerical simulations conducted with the explicit finite difference method show that the channel dimensions and the induced Lorentz forces have significant influences on the flow velocity profile. Furthermore, the simulation results agree well with the experimental results published by other researchers. PMID:15142583
Liquid-metal MHD machines for power and industry
Tolmach, I.M.
1987-07-01
The implementation and development of magnetohydrodynamic generators based on liquid metal working fluids in the power and other industries is reviewed on a global basis. The research and development carried out by several laboratories and manufacturers in pump and channel design and performance are evaluated. The hydraulic and magnetohydrodynamic behavior of liquid metals is assessed. Two categories of generators--single-phase alternating-current and direct-current generators--are explicitly discussed.
NASA Technical Reports Server (NTRS)
Wu, S. T.; Song, M. T.; Martens, P. C. H.; Dryer, M.
1991-01-01
A situation wherein a bipolar magnetic field embedded in a stratified solar atmosphere undergoes symmetrical shear motion at the footpoints is investigated via a 2D (nonplanar) MHD simulation. It was found that the vertical plasma flow velocities grow exponentially, leading to a new type of global MHD instability. The growth rate increases almost linearly until it reaches the same order of magnitude as the Alfven speed. Then a nonlinear MHD instability occurs beyond this point. It was found that the central loops are pinched by opposing Lorentz forces, and the outer closed loops stretch upward with the vertically-rising mass flow. The nonlinear dynamical shearing instability is illustrated by a numerical example that is given for three different values of the plasma beta that span several orders of magnitude.
NASA Astrophysics Data System (ADS)
Winkler, J.; Dahotre, N. B.; Boss, W.
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.
Numerical simulation model for the study of magneto-hydrodynamic (MHD) waves in a structured medium
Xiao, Y.
1988-01-01
This dissertation contains two basic parts: a formal development of a numerical simulation model for the study of MHD waves in a structured medium, and an application of the model to the investigation of the propagation of MHD waves in a magnetic slab and their interactions with nonmagnetic surroundings. The numerical model is a time-dependent, two-dimensional, and nonlinear MHD model with gravity and radiative energy loss. The corresponding numerical code is based on the newly developed SINIL (Semi-Implicit-Non-Iterative-Lagrangian) scheme. The MHD governing equations are discretized on a Lagrangian grid, using the control-volume method. The gas dynamic properties are solved explicitly, and the magnetic field is solved implicitly without using numerical iterations. Using this numerical model, three kinds of slab waves are studied, namely, kink type slab waves, sausage type slab waves, and kink-type single interface waves (which are considered as kink-type slab waves in the limit of infinite slab width). In this study, external acoustic waves can only be excited by internal body waves. The excitation of external acoustic waves represents the energy leakage from the internal magnetized region to the external field-free region.
Oxygen-enriched air for MHD power plants
NASA Technical Reports Server (NTRS)
Ebeling, R. W., Jr.; Cutting, J. C.; Burkhart, J. A.
1979-01-01
Cryogenic air-separation process cycle variations and compression schemes are examined. They are designed to minimize net system power required to supply pressurized, oxygen-enriched air to the combustor of an MHD power plant with a coal input of 2000 MWt. Power requirements and capital costs for oxygen production and enriched air compression for enrichment levels from 13 to 50% are determined. The results are presented as curves from which total compression power requirements can be estimated for any desired enrichment level at any delivery pressure. It is found that oxygen enrichment and recuperative heating of MHD combustor air to 1400 F yields near-term power plant efficiencies in excess of 45%. A minimum power compression system requires 167 MW to supply 330 lb of oxygen per second and costs roughly 100 million dollars. Preliminary studies show MHD/steam power plants to be competitive with plants using high-temperature air preheaters burning gas.
Evaluation of the ECAS open cycle MHD power plant design
NASA Technical Reports Server (NTRS)
Seikel, G. R.; Staiger, P. J.; Pian, C. C. P.
1978-01-01
The Energy Conversion Alternatives Study (ECAS) MHD/steam power plant is described. The NASA critical evaluation of the design is summarized. Performance of the MHD plant is compared to that of the other type ECAS plant designs on the basis of efficiency and the 30-year levelized cost of electricity. Techniques to improve the plant design and the potential performance of lower technology plants requiring shorter development time and lower development cost are then discussed.
A nonvariational code for calculating three-dimensional MHD (magnetohydrodynamic) equilibria
Greenside, H.S.; Reiman, A.H.; Salas, A.
1987-09-01
Details are presented of the PIES code, which uses a nonvariational algorithm for calculating fully three-dimensional MHD equilibria. The MHD equilibrium equations are directly iterated in special coordinates to find self-consistent currents and magnetic fields for given pressure and current profiles and for a given outermost magnetic surface. Three important advantages of this approach over previous methods are the ease with which net current profiles can be imposed, the explicit treatment of resonances, and the ability to handle magnetic islands and stochastic field lines. The convergence properties of the code are studied for several axisymmetric and nonaxisymmetric finite-..beta.. equilibria that have magnetic surfaces. 36 refs., 14 figs., 3 tabs.
Experiments in Magnetohydrodynamics
ERIC Educational Resources Information Center
Rayner, J. P.
1970-01-01
Describes three student experiments in magnetohydrodynamics (MHD). In these experiments, it was found that the electrical conductivity of the local water supply was sufficient to demonstrate effectively some of the features of MHD flowmeters, generators, and pumps. (LC)
Gigawatt, Closed Cycle, Vapor Core-Mhd Space Power System Conceptual Design Study
NASA Astrophysics Data System (ADS)
Wetch, Joseph R.; Rhee, Hyop S.; Koester, J. Kent; Goodman, Julius; Maya, Issac
1988-04-01
A conceptual design study for a closed cycle gigawatt electric space power system has been conducted. The closed cycle static operation reduces power system interaction effects upon the space craft. This system utilizes a very high temperature (5500 K) plasma core reactor and a magnetohydrodynamic (MHD) power conversion subsystem to provide a power density of about 8 kWe/kg (0.13 kg/kWe) for several kilo-seconds. Uranium vapor is the fuel. Candidate working fluids are metal vapors such as lithium or calcium. The system is based on a Rankine cycle to minimize the electromagnetic pumping power requirement. The fission fragment induced nonequilibrium ionization in the plasma in the MHD power duct provides the plasma electric conductivity for gigawatt power generation. Waste heat is rejected utilizing lithium heat pipes at temperatures just below 2000 K, thus minimizing the radiator area requirement. Key technology issues are identified, including the containment of the 5500 K 'sun-liken plasma at 4 to 0 MPa In a reflector moderated, gas/vapor filled cavity core reactor. A promising scheme to protect the refractory metal reactor inner wall is presented, together with a heating load analysis in the wall. This scheme utilizes an ablating film of liquid lithium/calcium that evaporates into the cavity core to become the working fluid of the cycle.
Design study of superconducting magnets for a combustion magnetohydrodynamic (MHD) generator
NASA Technical Reports Server (NTRS)
Thome, R. J.; Ayers, J. W.
1977-01-01
Design trade off studies for 13 different superconducting magnet systems were carried out. Based on these results, preliminary design characteristics were prepared for several superconducting magnet systems suitable for use with a combustion driven MHD generator. Each magnet generates a field level of 8 T in a volume 1.524 m (60 in.) long with a cross section 0.254 m x 0.254 m (10 in. x 10 in.) at the inlet and 0.406 m x .406 m (16 in. x 16 in.) at the outlet. The first design involves a racetrack coil geometry intended for operation at 4.2 K; the second design uses a racetrack geometry at 2.0 K; and the third design utilizes a rectangular saddle geometry at 4.2 K. Each case was oriented differently in terms of MHD channel axis and main field direction relative to gravity in order to evaluate fabrication ease. All cases were designed such that the system could be disassembled to allow for alteration of field gradient in the MHD channel by changing the angle between coils. Preliminary design characteristics and assembly drawings were generated for each case.
Berry, G.F.; Minkov, V.; Petrick, M.
1981-11-02
A magnetohydrodynamic (MHD) power generating system is described in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.
Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael
1988-01-01
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.
Multi-MW Closed Cycle MHD Nuclear Space Power Via Nonequilibrium He/Xe Working Plasma
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Harada, Nobuhiro
2011-01-01
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.
NASA Astrophysics Data System (ADS)
Lorzel, Heath
The time-dependent, 2-dimensional, axisymmetric, magnetohydrodynamics (MHD) solver MACH2 has been upgraded to include the effects of non-equilibrium air chemistry using the well-established reaction model developed by Park. Several validation cases are presented based on comparisons to the experimentally deduced shock stand-off distance of nitrogen flow over spheres, the shock stand-off distance of spheres fired into air in a ballistic test facility, and the electron number density on the surface of the Ram-C re-entry experiment. In addition, the magnetic induction equation has been upgraded with new verified models that compute the effects of the Hall and ion slip terms. The upgraded code is utilized to model an annular, Hall-type MHD generator that can be employed upstream of a turbojet engine for freestream conditions corresponding to Mach 5 flight at an altitude of 20km. The simulations demonstrate the feasibility of convening inlet kinetic power to storable electric power. Using ionization provided by electron-beam guns and a radial magnetic field B=3T, the generator is shown to produce a maximum of 4.8MW of electric power while reducing the total kinetic power of the flow by 31%. Optimizing the loading parameter, K*Load, across the electrodes demonstrates that the generator could produce 1.54MW of excess electric power that can be stored and used for on-board power requirements. Further, the reduction in flow kinetic power results in an increase in static pressure of 30% and a reduction in stagnation temperature of 3% at the turbojet's compressor inlet that aids the subsequent process of combustion.
NASA Astrophysics Data System (ADS)
Knight, Travis; Anghaie, Samim
2004-02-01
Very low specific-mass power generation in space is possible using Vapor Core Reactors with Magnetohydrodynamic (VCR/MHD) generator. These advanced reactors at the conceptual design level have potential for the generation of tens to hundreds of megawatts of power in space with specific mass of about 1 kg/kWe. Power for nuclear electric propulsion (NEP) is possible with almost direct power conditioning and coupling of the VCR/MHD power output to the VASIMR engine, MPD, and a whole host of electric thrusters. The VCR/MHD based NEP system is designed to power space transportation systems that dramatically reduce the mission time for human exploration of the entire solar system or for aggressive long-term robotic missions. There are more than 40 years of experience in the evaluation of the scientific and technical feasibility of gas and vapor core reactor concepts. The proposed VCR is based on the concept of a cavity reactor made critical through the use of a reflector such as beryllium or beryllium oxide. Vapor fueled cavity reactors that are considered for NEP applications operate at maximum core center and wall temperatures of 4000 K and 1500K, respectively. A recent investigation has resulted in the conceptual design of a uranium tetrafluoride fueled vapor core reactor coupled to a MHD generator. Detailed neutronic design and cycle analyses have been performed to establish the operating design parameters for 10 to 200 MWe NEP systems. An integral system engineering-simulation code is developed to perform parametric analysis and design optimization studies for the VCR/MHD power system. Total system weight and size calculated based on existing technology has proven the feasibility of achieving exceptionally low specific mass (? ~1 kg/kWe) with a VCR/MHD powered system.
MHD conversion of solar energy. [space electric power system
NASA Technical Reports Server (NTRS)
Lau, C. V.; Decher, R.
1978-01-01
Low temperature plasmas wherein an alkali metal vapor is a component are uniquely suited to simultaneously absorb solar radiation by coupling to the resonance lines and produce electrical power by the MHD interaction. This work is an examination of the possibility of developing space power systems which take advantage of concentrated solar power to produce electricity. It is shown that efficient cycles in which expansion work takes place at nearly constant top cycle temperature can be devised. The power density of the solar MHD generator is lower than that of conventional MHD generators because of the relatively high seed concentration required for radiation absorption and the lower flow velocity permitted to avoid total pressure losses due to heating.
Zhu, X. S.; Wang, H. N.; Du, Z. L.; Fan, Y. L.
2013-05-10
We undertake an attempt to reconstruct the Sun's non-force-free magnetic field. The solar corona is often considered to be magnetohydrostatic. We solve the full MHD equations with a semi-realistic atmosphere model to attain this stationary state. Our method is tested with a Sun-like model which simulates the emergence of a magnetic flux rope passing from below the photosphere into the corona. Detailed diagnostics shows that our method can model the forced field more successfully than the optimization and potential method, but it still needs to be applied to real data.
MHD boundary layer flow of a power-law nanofluid with new mass flux condition
NASA Astrophysics Data System (ADS)
Khan, Masood; Khan, Waqar Azeem
2016-02-01
An analysis is carried out to study the magnetohydrodynamic (" separators=" MHD ) boundary layer flow of power-law nanofluid over a non-linear stretching sheet. In the presence of a transverse magnetic field, the flow is generated due to non-linear stretching sheet. By using similarity transformations, the governing boundary layer equations are reduced into a system of ordinary differential equations. A recently proposed boundary condition requiring zero nanoparticle mass flux is employed in the flow analysis of power-law fluid. The reduced coupled differential equations are then solved numerically by the shooting method. The variations of dimensionless temperature and nanoparticle concentration with various parameters are graphed and discussed in detail. Numerical values of physical quantities such as the skin-friction coefficient and the reduced local Nusselt number are computed in tabular form.
Experimental determination of the MHD-EMP effects on power distribution transformers
McConnell, B.W.; Barnes, P.R. ); Tesche, F.M. , Dallas, TX )
1991-01-01
It is a well-established fact that geomagnetic storms influence electrical power transmission and distribution systems. Previous cases of such storms in the northern latitudes have resulted in occasional power disruptions, and in some cases, damage to transformers. These effects are caused by a time variation of the earth's magnetic field creating an induced electric field along the surface of the earth. This E-field acts as a voltage source along long power transmission or distribution lines, and if the line is connected to the earth at both ends, a quasi-dc current can flow. This current can cause unwanted saturation in the magnetic cores of transformers in the power system, and this, in turn produces harmonic distortion and transformer heating. This can lead to system upset (shutdown) and possibly transformer burn-out. The detonation of a high altitude nuclear explosion is also known to affect the magnetosphere, producing late-time variations of the earth's magnetic field for several hundreds of seconds. Known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), or E{sub 3}, this environment is of particular concern to electrical power systems in the event of a nuclear attack. Although the MHD-EMP induced currents can be significantly larger in magnitude, they last for a shorter period of time than do those from a geomagnetic storm. The effect of this environment compounds the adverse effects of the early-time high altitude EMP (HEMP) environment, posing a potentially serious threat to the electrical system. The present paper documents an experimental program designed to better understand the behavior of distribution-class transformers subjected to quasi-dc current excitation. Given the knowledge of the MHD-EMP-induced current flowing in a long power line, and the transformer response characteristics obtained in this program, it will be possible to make more accurate assessments of the behavior of the overall power system to EMP. 7 refs., 5 figs.
Oxygen-enriched air production for MHD power plants
NASA Astrophysics Data System (ADS)
1980-05-01
An analysis of several of the cryogenic air separation process cycle variations and compression schemes designed to minimize net system power requirements for supplying pressurized, oxygen-enriched air to the combustor of a 2000 MWt (coal input) baseload MHD power plant is presented.
Hua, T.Q.; Walker, J.S.; Picologlou, B.F.; Reed, C.B.
1988-07-01
Magnetohydrodynamic flows of liquid metals in rectangular ducts with thin conducting walls in the presence of strong nonuniform transverse magnetic fields are examined. The interaction parameter and Hartmann number are assumed to be large, whereas the magnetic Reynolds number is assumed to be small. Under these assumptions, viscous and inertial effects are confined in very thin boundary layers adjacent to the walls. A significant fraction of the fluid flow is concentrated in the boundary layers adjacent to the side walls which are parallel to the magnetic field. This paper describes the analysis and numerical methods for obtaining 3-D solutions for flow parameters outside these layers, without solving explicitly for the layers themselves. Numerical solutions are presented for cases which are relevant to the flows of liquid metals in fusion reactor blankets. Experimental results obtained from the ALEX experiments at Argonne National Laboratory are used to validate the numerical code. In general, the agreement is excellent. 5 refs., 14 figs.
MAGNETOHYDRODYNAMIC WAVES AND CORONAL HEATING: UNIFYING EMPIRICAL AND MHD TURBULENCE MODELS
Sokolov, Igor V.; Van der Holst, Bart; Oran, Rona; Jin, Meng; Manchester, Ward B. IV; Gombosi, Tamas I.; Downs, Cooper; Roussev, Ilia I.; Evans, Rebekah M.
2013-02-10
We present a new global model of the solar corona, including the low corona, the transition region, and the top of the chromosphere. The realistic three-dimensional magnetic field is simulated using the data from the photospheric magnetic field measurements. The distinctive feature of the new model is incorporating MHD Alfven wave turbulence. We assume this turbulence and its nonlinear dissipation to be the only momentum and energy source for heating the coronal plasma and driving the solar wind. The difference between the turbulence dissipation efficiency in coronal holes and that in closed field regions is because the nonlinear cascade rate degrades in strongly anisotropic (imbalanced) turbulence in coronal holes (no inward propagating wave), thus resulting in colder coronal holes, from which the fast solar wind originates. The detailed presentation of the theoretical model is illustrated with the synthetic images for multi-wavelength EUV emission compared with the observations from SDO AIA and STEREO EUVI instruments for the Carrington rotation 2107.
NASA Technical Reports Server (NTRS)
Wang, A. H.; Wu, S. T.; Liu, Yang; Hathaway, D.
2008-01-01
We introduce a numerical simulation method for recovering the photospheric velocity field from the vector magnetograms. The traditional method is local correlation tracking (LCT) which is based on measuring the relative displacements of features in blocks of pixels between successive white-light images or magnetograms. Within this method, there are a variety of implementations. One of recently developed implementations is induction local correlation tracking (ILCT) as described by Welsch et al. (2004). They employ the normal component of magnetic induction equation as a constraint to assure consistent solutions. Our numerical method uses the fully three-dimensional MHD equations to recover the photospheric velocity field with individual vector magnetograms. We compare our method to the ILCT method using NOAA AR8210 as an example. The differences and similarities are discussed in detail.
Hua, T.A.; Picologlou, B.F.; Reed, C.B.; Walker, J.S.
1988-02-01
Magnetohydrodynamic flows of liquid metals in thin conducting ducts of various geometries in the presence of strong nonuniform transverse magnetic fields are examined. The interaction parameter and Hartmann number are assumed to be large, whereas the magnetic Reynolds number is assumed to be small. Under these assumptions, viscous and inertial effects are confined in very thin boundary layers adjacent to the walls. At walls parallel to the magnetic field lines, as at the side walls of a rectangular duct, the boundary layers (side layers) carry a significant fraction of the volumetric flow rate in the form of high velocity jets. The presence of these jets strongly enhances heat transfer performance. In addition, heat transfer can be further improved by guiding the flow toward a heated wall by proper variation of wall thicknesses, duct cross sectional dimensions and/or shape. Flows in nonconducting circular ducts are also examined. Experimental results obtained from the ALEX experiments at the Argonne National Laboratory are used to validate the numerical predictions. 6 refs., 7 figs.
Design study of superconducting magnets for a combustion magnetohydrodynamic /MHD/ generator
NASA Technical Reports Server (NTRS)
Thome, R. J.; Ayers, J. W.; Hrycaj, T. M.; Burkhart, J. A.
1978-01-01
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.
H2-O2 combustion powered steam-MHD central power systems
NASA Technical Reports Server (NTRS)
Seikel, G. R.; Smith, J. M.; Nichols, L. D.
1974-01-01
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.
A liquid metal MHD concept for multimegawatt space power application
NASA Astrophysics Data System (ADS)
Bilton, J. R.; Hensler, R. L.; Walker, V. A.; Rushton, B. L.; Ambrosek, R. G.; Schnitzler, B. G.; Wheeler, F. J.; Storhok, V. W.; Lake, J. A.; Wadkins, R. P.
The need for space power at very high levels in the hundreds of megawatts range, for short period of time, coupled with the need for moderately high power levels, in the tens of megawatts for extended periods, places unique requirements on the energy system designer. The system discussed is designed to meet the requirements for burst power levels of 300 to 600 MWe and alert power of less than 50 MWe. For a space power system, high reliability and low specific weight and volume are driving requirements. Efficiency is important to the extent that it influences system weight and low efficiency places extreme requirements on the energy source. Liquid metal MHD is a passive energy conversion process and thereby minimizes the number of rotating components. A liquid metal cooled fast reactor provides the heat source for the liquid metal MHD working fluid, while retaining a relatively compact core configuration for this range of powers. The power system studied is based on a two phase flow liquid metal MHD generator with lithium as the electrodynamic fluid and helium as the thermodynamic fluid.
Performance calculations for 1000 MWe MHD/steam power plants
NASA Technical Reports Server (NTRS)
Pian, C. C. P.
1981-01-01
The effects of MHD generator operating conditions and constraints on the performance of MHD/steam power plants are investigated. Power plants using high temperature combustion air preheat (2500 F) and plants using intermediate temperature preheat (1100 F) with oxygen enrichment are considered. Variations of these two types of power plants are compared on the basis of fixed total electrical output (1000 MWe). Results are presented to show the effects of generator plant length and level of oxygen enrichment on the plant thermodynamic efficiency and on the required generator mass flow rate. Factors affecting the optimum levels of oxygen enrichment are analyzed. It is shown that oxygen enrichment can reduce magnet stored energy requirement.
NASA Astrophysics Data System (ADS)
Finley, Charles J.
1994-07-01
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.
MHD-EMP and electric power systems
Barnes, P.R.; Rizy, D.T. ); Tesche, F.M. , Dallas, TX )
1992-01-01
A solar-induced geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms have caused a range of equipment and operating problems for electric power systems; the most noteably problems according in March 1989. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years as power system systems have become more interconnected and as transmission lines have increased in length, and because power systems are now operated closer to their limits than in the past. In this paper, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It is found that electric power systems are susceptible to geomagnetically-induced earth-surface potential gradients as small as a few (2 to 3) volts per kilometer corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects of GMDs are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced GMDs and the response of power systems to these types of storms. A better understanding of GMDs and the power systems response to GMDs is needed so that mitigation measures can be implemented which will make power systems less susceptible to severe geomagnetic disturbances. 3 refs.
MHD-EMP and electric power systems
Barnes, P.R.; Rizy, D.T.; Tesche, F.M.
1992-03-01
A solar-induced geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms have caused a range of equipment and operating problems for electric power systems; the most noteably problems according in March 1989. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years as power system systems have become more interconnected and as transmission lines have increased in length, and because power systems are now operated closer to their limits than in the past. In this paper, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It is found that electric power systems are susceptible to geomagnetically-induced earth-surface potential gradients as small as a few (2 to 3) volts per kilometer corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects of GMDs are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced GMDs and the response of power systems to these types of storms. A better understanding of GMDs and the power systems response to GMDs is needed so that mitigation measures can be implemented which will make power systems less susceptible to severe geomagnetic disturbances. 3 refs.
Impinging jet separators for liquid metal magnetohydrodynamic power cycles
NASA Technical Reports Server (NTRS)
Bogdanoff, D. W.
1973-01-01
In many liquid metal MHD power, cycles, it is necessary to separate the phases of a high-speed liquid-gas flow. The usual method is to impinge the jet at a glancing angle against a solid surface. These surface separators achieve good separation of the two phases at a cost of a large velocity loss due to friction at the separator surface. This report deals with attempts to greatly reduce the friction loss by impinging two jets against each other. In the crude impinging jet separators tested to date, friction losses were greatly reduced, but the separation of the two phases was found to be much poorer than that achievable with surface separators. Analyses are presented which show many lines of attack (mainly changes in separator geometry) which should yield much better separation for impinging jet separators).
MHD Advanced Power Train Phase I, Final Report, Volume 7
A. R. Jones
1985-08-01
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.
Towards Integrated Pulse Detonation Propulsion and MHD Power
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Thompson, Bryan R.; Lineberry, John T.
1999-01-01
The interest in pulse detonation engines (PDE) arises primarily from the advantages that accrue from the significant combustion pressure rise that is developed in the detonation process. Conventional rocket engines, for example, must obtain all of their compression from the turbopumps, while the PDE provides additional compression in the combustor. Thus PDE's are expected to achieve higher I(sub sp) than conventional rocket engines and to require smaller turbopumps. The increase in I(sub sp) and the decrease in turbopump capacity must be traded off against each other. Additional advantages include the ability to vary thrust level by adjusting the firing rate rather than throttling the flow through injector elements. The common conclusion derived from these aggregated performance attributes is that PDEs should result in engines which are smaller, lower in cost, and lighter in weight than conventional engines. Unfortunately, the analysis of PDEs is highly complex due to their unsteady operation and non-ideal processes. Although the feasibility of the basic PDE concept has been proven in several experimental and theoretical efforts, the implied performance improvements have yet to be convincingly demonstrated. Also, there are certain developmental issues affecting the practical application of pulse detonation propulsion systems which are yet to be fully resolved. Practical detonation combustion engines, for example, require a repetitive cycle of charge induction, mixing, initiation/propagation of the detonation wave, and expulsion/scavenging of the combustion product gases. Clearly, the performance and power density of such a device depends upon the maximum rate at which this cycle can be successfully implemented. In addition, the electrical energy required for direct detonation initiation can be significant, and a means for direct electrical power production is needed to achieve self-sustained engine operation. This work addresses the technological issues associated with PDEs for integrated aerospace propulsion and MHD power. An effort is made to estimate the energy requirements for direct detonation initiation of potential fuel/oxidizer mixtures and to determine the electrical power requirements. This requirement is evaluated in terms of the possibility for MHD power generation using the combustion detonation wave. Small scale laboratory experiments were conducted using stoichiometric mixtures of acetylene and oxygen with an atomized spray of cesium hydroxide dissolved in alcohol as an ionization seed in the active MHD region. Time resolved thrust and MHD power generation measurements were performed. These results show that PDEs yield higher I(sub sp) levels than a comparable rocket engine and that MHD power generation is viable candidate for achieving self-excited engine operation.
NASA Technical Reports Server (NTRS)
Wu, S. T.; Panitchob, S.
1986-01-01
Solar flare energy buildup at the photospheric level and energy release and transport into heliospheric space are examined using a composite MHD model. A four phase composite MHD model is described. An example demonstrating the applicability of the model is presented; the model was applied to the active region AR 2372. The limitations of this composite MHD model approach to analyzing solar flare energy buildup are discussed.
Plasma plume MHD power generator and method
Hammer, J.H.
1993-08-10
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.
NASA Astrophysics Data System (ADS)
Jiao, Chengru; Zheng, Liancun; Ma, Lianxi
2015-08-01
This paper studies the magnetohydrodynamic (MHD) thermosolutal Marangoni convection heat and mass transfer of power-law fluids driven by a power law temperature and a power law concentration which is assumed that the surface tension varies linearly with both the temperature and concentration. Heat and mass transfer constitutive equation is proposed based on N-diffusion proposed by Philip and the abnormal convection-diffusion model proposed by Pascal in which we assume that the heat diffusion depends non-linearly on both the temperature and the temperature gradient and the mass diffusion depends non-linearly on both the concentration and the concentration gradient with modified Fourier heat conduction for power law fluid. The governing equations are reduced to nonlinear ordinary differential equations by using suitable similarity transformations. Approximate analytical solution is obtained using homotopy analytical method (HAM). The transport characteristics of velocity, temperature and concentration fields are analyzed in detail.
Comparative analysis of CCMHD power plants. [Closed Cycle MHD
NASA Technical Reports Server (NTRS)
Alyea, F. N.; Marston, C. H.; Mantri, V. B.; Geisendorfer, B. G.; Doss, H.
1981-01-01
A study of Closed Cycle MHD (CCMHD) power generation systems has been conducted which emphasizes both advances in component conceptual design and overall system performance. New design data are presented for the high temperature, regenerative argon heaters (HTRH) and the heat recovery/seed recovery (HRSR) subsystem. Contamination of the argon by flue gas adsorbed in the HTRH is examined and a model for estimation of contamination effects in operating systems is developed. System performance and cost data have been developed for the standard CCMHD/steam cycle as powered by both direct fired cyclone combustors and selected coal gasifiers. In addition, a new CCMHD thermodynamic cycle has been identified.
Magnetohydrodynamic turbulence: Observation and experiment
Brown, M. R.; Schaffner, D. A.; Weck, P. J.
2015-05-15
We provide a tutorial on the paradigms and tools of magnetohydrodynamic (MHD) turbulence. The principal paradigm is that of a turbulent cascade from large scales to small, resulting in power law behavior for the frequency power spectrum for magnetic fluctuations E{sub B}(f). We will describe five useful statistical tools for MHD turbulence in the time domain: the temporal autocorrelation function, the frequency power spectrum, the probability distribution function of temporal increments, the temporal structure function, and the permutation entropy. Each of these tools will be illustrated with an example taken from MHD fluctuations in the solar wind. A single dataset from the Wind satellite will be used to illustrate all five temporal statistical tools.
System studies of coal fired-closed cycle MHD for central station power plants
NASA Technical Reports Server (NTRS)
Zauderer, B.
1976-01-01
This paper presents a discussion of the closed-cycle MHD results obtained in a recent study of various advanced energy-conversion power systems. The direct coal-fired MHD topping-steam bottoming cycle was established as the current choice for central station power generation. Emphasis is placed on the background assumptions and the conclusions that can be drawn from the closed-cycle MHD analysis. It is concluded that closed-cycle MHD has efficiencies comparable to that of open-cycle MHD. Its cost will possibly be slightly higher than that of the open-cycle MHD system. Also, with reasonable fuel escalation assumptions, both systems can produce lower-cost electricity than conventional steam power plants. Suggestions for further work in closed-cycle MHD components and systems are made.
Experiments on H2-O2MHD power generation
NASA Technical Reports Server (NTRS)
Smith, J. M.
1980-01-01
Magnetohydrodynamic power generation experiments utilizing a cesium-seeded H2-O2 working fluid were carried out using a diverging area Hall duct having an entrance Mach number of 2. The experiments were conducted in a high-field strength cryomagnet facility at field strengths up to 5 tesla. The effects of power takeoff location, axial duct location within the magnetic field, generator loading, B-field strength, and electrode breakdown voltage were investigated. For the operating conditions of these experiments, it is found that the power output increases with the square of the B-field and can be limited by choking of the channel or interelectrode voltage breakdown which occurs at Hall fields greater than 50 volts/insulator. Peak power densities of greater than 100 MW/cu M were achieved.
Magnetohydrodynamic energy conversion by using convexly divergent channel
Murakami, Tomoyuki; Okuno, Yoshihiro
2009-12-21
We describe a magnetohydrodynamic (MHD) electrical power generator equipped with a convexly divergent channel, as determined through shock-tunnel-based experiments. The quality of MHD power-generating plasma and the energy conversion efficiency in the convexly divergent channel are compared with those from previous linearly divergent channel. The divergence enhancement in the channel upstream is effective for suppressing an excessive increase in static pressure, whereby notably high isentropic efficiency is achieved.
Gyroscopic analog for magnetohydrodynamics
Holm, D.D.
1981-01-01
The gross features of plasma equilibrium and dynamics in the ideal magnetohydrodynamics (MHD) model can be understood in terms of a dynamical system which closely resembles the equations for a deformable gyroscope.
Gyroscopic analog for magnetohydrodynamics
Holm, D.D.
1982-07-20
The gross features of plasma equilibrium and dynamics in the ideal magnetohydrodynamics (MHD) model can be understood in terms of a dynamical system which closely resembles the equations for a deformable gyroscope.
NASA Technical Reports Server (NTRS)
Riggins, David W.
2002-01-01
The performance of the MHD energy bypass air-breathing engine for high-speed propulsion is analyzed in this investigation. This engine is a specific type of the general class of inverse cycle engines. In this paper, the general relationship between engine performance (specific impulse and specific thrust) and the overall total pressure ratio through an engine (from inlet plane to exit plane) is first developed and illustrated. Engines with large total pressure decreases, regardless of cause or source, are seen to have exponentially decreasing performance. The ideal inverse cycle engine (of which the MHD engine is a sub-set) is then demonstrated to have a significant total pressure decrease across the engine; this total pressure decrease is cycle-driven, degrades rapidly with energy bypass ratio, and is independent of any irreversibility. The ideal MHD engine (inverse cycle engine with no irreversibility other than that inherent in the MHD work interaction processes) is next examined and is seen to have an additional large total pressure decrease due to MHD-generated irreversibility in the decelerator and the accelerator. This irreversibility mainly occurs in the deceleration process. Both inherent total pressure losses (inverse cycle and MHD irreversibility) result in a significant narrowing of the performance capability of the MHD bypass engine. The fundamental characteristics of MHD flow acceleration and flow deceleration from the standpoint of irreversibility and second-law constraints are next examined in order to clarify issues regarding flow losses and parameter selection in the MM modules. Severe constraints are seen to exist in the decelerator in terms of allowable deceleration Mach numbers and volumetric (length) required for meaningful energy bypass (work interaction). Considerable difficulties are also encountered and discussed due to thermal/work choking phenomena associated with the deceleration process. Lastly, full engine simulations utilizing inlet shock systems, finite-rate chemistry, wall cooling with thermally balanced engine (fuel heat sink), fuel injection and mixing, friction, etc. are shown and discussed for both the MHD engine and the conventional scramjet. The MHD bypass engine has significantly lower performance in all categories across the Mach number range (8 to 12.2). The lower performance is attributed to the combined effects of 1) additional irreversibility and cooling requirements associated with the MHD components and 2) the total pressure decrease associated with the inverse cycle itself.
Metal-ammonia MHD - A compact high-power marine propulsion engine
NASA Astrophysics Data System (ADS)
Johnson, Martin R.
1990-07-01
Metal-ammonia plasmas are electrically conductive, condensible fluids capable of unprecedented power densities in MHD power generation. This paper discusses the physical and chemical properties of MA plasmas, and presents a model for MHD duct performance predicting 100 MW power output from a 4 meter long duct. Problems of plasma stability are discussed.
Experiments on H2-O2 MHD power generation
NASA Astrophysics Data System (ADS)
Smith, J. M.
1980-06-01
MHD power generation experiments utilizing a cesium-seeded H2-O2 working fluid have been carried out using a diverging area Hall duct having an entrance Mach number of 2. The experiments are conducted in a high-field strength cryomagnet facility at field strengths up to 5 tesla. The effects of power takeoff location, axial duct location within the magnetic field, generator loading, B-field strength, and electrode breakdown voltage were investigated. For the operating conditions of these experiments it is found that the power output increases with the square of the B-field and can be limited by choking of the channel or interelectrode voltage breakdown which occurs at Hall fields greater than 50 volts/insulator.
Engineering support for magnetohydrodynamic power plant analysis and design studies
NASA Technical Reports Server (NTRS)
Carlson, A. W.; Chait, I. L.; Marchmont, G.; Rogali, R.; Shikar, D.
1980-01-01
The major factors which influence the economic engineering selection of stack inlet temperatures in combined cycle MHD powerplants are identified and the range of suitable stack inlet temperatures under typical operating conditions is indicated. Engineering data and cost estimates are provided for four separately fired high temperature air heater (HTAH) system designs for HTAH system thermal capacity levels of 100, 250, 500 and 1000 MWt. An engineering survey of coal drying and pulverizing equipment for MHD powerplant application is presented as well as capital and operating cost estimates for varying degrees of coal pulverization.
Computer controlled MHD power consolidation and pulse generation system
Johnson, R.; Marcotte, K.; Donnelly, M.
1990-01-01
The major goal of this research project is to establish the feasibility of a power conversion technology which will permit the direct synthesis of computer programmable pulse power. Feasibility has been established in this project by demonstration of direct synthesis of commercial frequency power by means of computer control. The power input to the conversion system is assumed to be a Faraday connected MHD generator which may be viewed as a multi-terminal dc source and is simulated for the purpose of this demonstration by a set of dc power supplies. This consolidation/inversion (CI), process will be referred to subsequently as Pulse Amplitude Synthesis and Control (PASC). A secondary goal is to deliver a controller subsystem consisting of a computer, software, and computer interface board which can serve as one of the building blocks for a possible phase II prototype system. This report period work summarizes the accomplishments and covers the high points of the two year project. 6 refs., 41 figs.
NASA Astrophysics Data System (ADS)
Wang, Qiang; Rong, Wenjie; Li, Baokuan
2015-11-01
A transient three-dimensional (3D) coupled mathematical model of electroslag remelting (ESR) furnace has been developed to investigate the impact of power control function on the heat transfer and magnetohydrodynamic (MHD) two-phase flow. Maxwell's equations are solved by electrical potential method. The volume of fluid (VOF) approach is implemented to describe the two phase flow. The Lorentz force and the Joule heating are updated at each iteration as a function of phase distribution. The solidification is modeled by enthalpy-porosity formulation. A reasonable agreement between the experiment and simulation is obtained. The melt rate increases 15.83% in the remelting process with a constant current of 1600 A. With the power control function, the current would be reduced if the melt rate is 1.05 times larger than its initial value. The fluctuation range of the melt rate therefore decreases to 7.23%. Moreover, the fluctuation is limited within 5.12% if we start the power control program when the melt rate is 1.03 times higher than its initial value. Not only the metal pool depth but also the input power decreases under the effect of the current control function.
Radio-frequency power-assisted performance improvement of a magnetohydrodynamic power generator
NASA Astrophysics Data System (ADS)
Murakami, Tomoyuki; Okuno, Yoshihiro; Yamasaki, Hiroyuki
2005-12-01
We describe a radio-frequency (rf) electromagnetic-field-assisted magnetohydrodynamic power generation experiment, where an inductively coupled rf field (13.56MHz, 5.2kW) is continuously supplied to the disk generator. The rf power assists the precise plasma ignition, by which the otherwise irregular plasma behavior was stabilized. The rf heating suppresses the ionization instability in the plasma behavior and homogenizes the nonuniformity of the plasma structures. The power-generating performance is significantly improved with the aid of the rf power under wide seeding conditions: insufficient, optimum, and excessive seed fractions. The increment of the enthalpy extraction ratio of around 2% is significantly greater than the fraction of the net rf power, that is, 0.16%, to the thermal input.
MHD Energy Bypass Scramjet Engine
NASA Technical Reports Server (NTRS)
Mehta, Unmeel B.; Bogdanoff, David W.; Park, Chul; Arnold, Jim (Technical Monitor)
2001-01-01
Revolutionary rather than evolutionary changes in propulsion systems are most likely to decrease cost of space transportation and to provide a global range capability. Hypersonic air-breathing propulsion is a revolutionary propulsion system. The performance of scramjet engines can be improved by the AJAX energy management concept. A magneto-hydro-dynamics (MHD) generator controls the flow and extracts flow energy in the engine inlet and a MHD accelerator downstream of the combustor accelerates the nozzle flow. A progress report toward developing the MHD technology is presented herein. Recent theoretical efforts are reviewed and ongoing experimental efforts are discussed. The latter efforts also include an ongoing collaboration between NASA, the US Air Force Research Laboratory, US industry, and Russian scientific organizations. Two of the critical technologies, the ionization of the air and the MHD accelerator, are briefly discussed. Examples of limiting the combustor entrance Mach number to a low supersonic value with a MHD energy bypass scheme are presented, demonstrating an improvement in scramjet performance. The results for a simplified design of an aerospace plane show that the specific impulse of the MHD-bypass system is better than the non-MHD system and typical rocket over a narrow region of flight speeds and design parameters. Equilibrium ionization and non-equilibrium ionization are discussed. The thermodynamic condition of air at the entrance of the engine inlet determines the method of ionization. The required external power for non-equilibrium ionization is computed. There have been many experiments in which electrical power generation has successfully been achieved by magneto-hydrodynamic (MHD) means. However, relatively few experiments have been made to date for the reverse case of achieving gas acceleration by the MHD means. An experiment in a shock tunnel is described in which MHD acceleration is investigated experimentally. MHD has several potential aerospace applications. The first is to improve the performance of hypersonic air-breathing engines for space launch and cruise vehicles. The second is to improve the performance of a high enthalpy wind tunnel. The third is to control a hypersonic vehicle. With such applications in mind, theoretical and experiments are being conducted at the NASA Ames Research Center to develop the MHD technology.
Parametric study of potential early commercial MHD power plants
NASA Technical Reports Server (NTRS)
Hals, F. A.
1979-01-01
Three different reference power plant configurations were considered with parametric variations of the various design parameters for each plant. Two of the reference plant designs were based on the use of high temperature regenerative air preheaters separately fired by a low Btu gas produced from a coal gasifier which was integrated with the power plant. The third reference plant design was based on the use of oxygen enriched combustion air preheated to a more moderate temperature in a tubular type metallic recuperative heat exchanger which is part of the bottoming plant heat recovery system. Comparative information was developed on plant performance and economics. The highest net plant efficiency of about 45 percent was attained by the reference plant design with the use of a high temperature air preheater separately fired with the advanced entrained bed gasifier. The use of oxygen enrichment of the combustion air yielded the lowest cost of generating electricity at a slightly lower plant efficiency. Both of these two reference plant designs are identified as potentially attractive for early MHD power plant applications.
System studies of coal fired-closed cycle MHD for central station power plants
NASA Technical Reports Server (NTRS)
Zauderer, B.
1976-01-01
This paper presents a discussion of the closed cycle MHD results obtained in a recent study of various advanced energy conversion (ECAS) power systems. The study was part of the first phase of this ECAS study. Since this was the first opportunity to evaluate the coal fired closed cycle MHD system, a number of iterations were required to partially optimize the system. The present paper deals with the latter part of the study in which the direct coal fired, MHD topping-steam bottoming cycle was established as the current choice for central station power generation. The emphasis of the paper is on the background assumptions and the conclusions that can be drawn from the closed cycle MHD analysis. The author concludes that closed cycle MHD has efficiencies comparable to that of open cycle MHD and that both systems are considerably more efficient than the other system studies in Phase 1 of the GE ECAS. Its cost will possibly be slightly higher than that of the open cycle MHD system. Also, with reasonable fuel escalation assumptions, both systems can produce lower cost electricity than conventional steam power plants. Suggestions for further work in closed cycle MHD components and systems is made.
NASA Technical Reports Server (NTRS)
Dellinger, T. C.; Hnat, J. G.; Marston, C. H.
1979-01-01
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.
Studies of cycles for liquid-metal magnetohydrodynamic generation of power
NASA Technical Reports Server (NTRS)
Lee, K.; Petrick, M.
1969-01-01
Studies of liquid-metal magnetohydrodynamic power cycles indicate that the overall efficiency of a binary cycle, employing a liquid-metal topping cycle and a bottoming steam cycle, may reach 60 percent. Details of analyses and data on cycles are presented, and the commercial potential of the binary cycle is discussed.
MHD Integrated Topping Cycle Project
Not Available
1992-03-01
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.
NASA Technical Reports Server (NTRS)
Wu, S. T.; Guo, W. P.
1997-01-01
We present results for an investigation of the interaction of a helmet streamer arcade and a helical flux-rope emerging from the sub-photosphere. These results are obtained by using a three-dimensional axisymmetric, time-dependent ideal magnetohydrodynamic (MHD) model. Because of the physical nature of the flux-rope, we investigate two types of flux-ropes; (1) high density flux-rope (i.e. flux-rope without cavity), and (2) low density flux rope (i.e. flux-rope with cavity). When the streamer is disrupted by the flux-rope, it will evolve into a configuration resembling the typical observed loop-like Coronal Mass Ejection (CMES) for both cases. The streamer-flux rope system with cavity is easier to be disrupted and the propagation speed of the CME is faster than the streamer-flux rope system without cavity. Our results demonstrate that magnetic buoyancy force plays an important role in disrupting the streamer.
A summary of the ECAS MHD power plant results
NASA Technical Reports Server (NTRS)
Seikel, G. R.; Harris, L. P.
1976-01-01
The performance and the cost of electricity (COE) for MHD systems utilizing coal or coal derived fuels are summarized along with a conceptual open cycle MHD plant design. The results show that open cycle coal fired recuperatively preheated MHD systems have potentially one of the highest coal-pile-to-bus bar efficiencies (48.3%) and also one of the lowest COE of the systems studied. Closed cycle, inert gas systems do not appear to have the potential of exceeding the efficiency of or competing with the COE of advanced steam plants.
Parametric study of potential early commercial power plants Task 3-A MHD cost analysis
NASA Technical Reports Server (NTRS)
1983-01-01
The development of costs for an MHD Power Plant and the comparison of these costs to a conventional coal fired power plant are reported. The program is divided into three activities: (1) code of accounts review; (2) MHD pulverized coal power plant cost comparison; (3) operating and maintenance cost estimates. The scope of each NASA code of account item was defined to assure that the recently completed Task 3 capital cost estimates are consistent with the code of account scope. Improvement confidence in MHD plant capital cost estimates by identifying comparability with conventional pulverized coal fired (PCF) power plant systems is undertaken. The basis for estimating the MHD plant operating and maintenance costs of electricity is verified.
NASA Astrophysics Data System (ADS)
Barnes, P. R.; Vance, E. F.
A nuclear detonation at altitudes several hundred kilometers above the earth will severely distort the earth's magnetic field and result in a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). The geomagnetic disturbance interacts with the soil to induce current and horizontal electric gradients. MHD-EMP, also called E3 since it is the third component of the high-altitude EMP (HEMP), lasts over 100 s after an exoatmospheric burst. MHD-EMP is similar to solar geomagnetic storms in it's global and low frequency (less than 1 Hz) nature except that E3 can be much more intense with a far shorter duration. When the MHD-EMP gradients are integrated over great distances by power lines, communication cables, or other long conductors, the induced voltages are significant. (The horizontal gradients in the soil are too small to induce major responses by local interactions with facilities.) The long pulse waveform for MHD-EMP-induced currents on long lines has a peak current of 200 A and a time-to-half-peak of 100 s. If this current flows through transformer windings, it can saturate the magnetic circuit and cause 60 Hz harmonic production. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building and the commercial power harmonics and voltage swings must be addressed. The transfer switch would be expected to respond to the voltage fluctuations as long as the harmonics have not interfered with the switch control circuitry. The major sources of MHD-EMP induced currents are the commercial power lines and neutral; neutral current indirect coupling to the facility power or ground system via the metal fence, powered gate, parking lights, etc; metal water pipes; phone lines; and other long conductors that enter or come near the facility. The major source of harmonics is the commercial power system.
Magnetohydrodynamic fluidic system
Lee, Abraham P.; Bachman, Mark G.
2004-08-24
A magnetohydrodynamic fluidic system includes a reagent source containing a reagent fluid and a sample source containing a sample fluid that includes a constituent. A reactor is operatively connected to the supply reagent source and the sample source. MHD pumps utilize a magnetohydrodynamic drive to move the reagent fluid and the sample fluid in a flow such that the reagent fluid and the sample fluid form an interface causing the constituent to be separated from the sample fluid.
Ultrahigh temperature vapor core reactor-MHD system for space nuclear electric power
NASA Technical Reports Server (NTRS)
Maya, Isaac; Anghaie, Samim; Diaz, Nils J.; Dugan, Edward T.
1991-01-01
The conceptual design of a nuclear space power system based on the ultrahigh temperature vapor core reactor with MHD energy conversion is presented. This UF4 fueled gas core cavity reactor operates at 4000 K maximum core temperature and 40 atm. Materials experiments, conducted with UF4 up to 2200 K, demonstrate acceptable compatibility with tungsten-molybdenum-, and carbon-based materials. The supporting nuclear, heat transfer, fluid flow and MHD analysis, and fissioning plasma physics experiments are also discussed.
Samim Anghaie; Blair Smith; Travis Knight
2002-11-12
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.
Compendium of MHD-related terminology
NASA Astrophysics Data System (ADS)
Hart, A. T.; Lofftus, D. A.; Rudberg, D. A.; Green, R. A.
The magnetohydrodynamic (MHD) researchers in the United States have joined together in the past few years to prove the viability of the technology. As new designs for hardware methods of operation, approaches for data analysis, and levels of understanding have been attained, a set of MHD-unique terminology has been developed but not always documented. A glossary of terminology unique to the study of MHD was compiled for SEAM 27 to provide an information source for workers in this field and to assist those interested in the commercial potential of MHD in reading and understanding technical articles on the subject. The terminology defined was primarily related to the U.S. proof-of-concept program of MHD development and eventual retrofitting of a coal fired plant with MHD equipment. Basic theoretical terms as well as terminology related to the commercialization of MHD were presented. Emphasis was placed on terms related to commercialization and those related to currently active areas of study. This paper builds on the SEAM 27 contribution. Areas of concentration in this paper are retrofit/power plant terminology, advanced measurement technology applicable to MHD, research sites.
Double-duct liquid metal magnetohydrodynamic engine
Haaland, Carsten M.
1997-01-01
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.
Double-duct liquid metal magnetohydrodynamic engine
Haaland, Carsten M.
1995-01-01
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.
Efficient magnetohydrodynamic simulations on graphics processing units with CUDA
NASA Astrophysics Data System (ADS)
Wong, Hon-Cheng; Wong, Un-Hong; Feng, Xueshang; Tang, Zesheng
2011-10-01
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.
Entropy generation analysis of magnetohydrodynamic induction devices
NASA Astrophysics Data System (ADS)
Salas, Hugo; Cuevas, Sergio; Lpez de Haro, Mariano
1999-10-01
Magnetohydrodynamic (MHD) induction devices such as electromagnetic pumps or electric generators are analysed within the approach of entropy generation. The flow of an electrically-conducting incompressible fluid in an MHD induction machine is described through the well known Hartmann model. Irreversibilities in the system due to ohmic dissipation, flow friction and heat flow are included in the entropy-generation rate. This quantity is used to define an overall efficiency for the induction machine that considers the total loss caused by process irreversibility. For an MHD generator working at maximum power output with walls at constant temperature, an optimum magnetic field strength (i.e. Hartmann number) is found based on the maximum overall efficiency.
Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Cole, John; Lineberry, John; Chapman, Jim; Schmidt, Harold; Cook, Stephen (Technical Monitor)
2002-01-01
A fundamental obstacle to routine space access is the specific energy limitations associated with chemical fuels. In the case of vertical take-off, the high thrust needed for vertical liftoff and acceleration to orbit translates into power levels in the 10 GW range. Furthermore, useful payload mass fractions are possible only if the exhaust particle energy (i.e., exhaust velocity) is much greater than that available with traditional chemical propulsion. The electronic binding energy released by the best chemical reactions (e.g., LOX/LH2 for example, is less than 2 eV per product molecule (approx. 1.8 eV per H2O molecule), which translates into particle velocities less than 5 km/s. Useful payload fractions, however, will require exhaust velocities exceeding 15 km/s (i.e., particle energies greater than 20 eV). As an added challenge, the envisioned hypothetical RLV (reusable launch vehicle) should accomplish these amazing performance feats while providing relatively low acceleration levels to orbit (2-3g maximum). From such fundamental considerations, it is painfully obvious that planned and current RLV solutions based on chemical fuels alone represent only a temporary solution and can only result in minor gains, at best. What is truly needed is a revolutionary approach that will dramatically reduce the amount of fuel and size of the launch vehicle. This implies the need for new compact high-power energy sources as well as advanced accelerator technologies for increasing engine exhaust velocity. Electromagnetic acceleration techniques are of immense interest since they can be used to circumvent the thermal limits associated with conventional propulsion systems. This paper describes the Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) being undertaken at NASA Marshall Space Flight Center (MSFC). In this experiment, a 1-MW arc heater is being used as a feeder for a 1-MW magnetohydrodynamic (MHD) accelerator. The purpose of the experiment is to demonstrate that an MHD accelerator can be an effective augmentation system for increasing engine exhaust velocity. More specifically, the experiment is intended to show that electromagnetic effects are effective at producing flow acceleration whereas electrothermal effects do not cause unacceptable heating of the working fluid. The MHD accelerator was designed as an externally diagonalized segmented Faraday channel, which will be inserted into an existing 2-tesla electromagnet. This allows the external power to be connected through two terminals thereby minimizing the complexity and cost associated with powering each segment independently. The design of the accelerator and other components in the flow path has been completed and fabrication activities are underway. This paper provides a full description of MAPX including performance analysis, design, and test plans, and current status.
Exploratory study of several advanced nuclear-MHD power plant systems.
NASA Technical Reports Server (NTRS)
Williams, J. R.; Clement, J. D.; Rosa, R. J.; Yang, Y. Y.
1973-01-01
In order for efficient multimegawatt closed cycle nuclear-MHD systems to become practical, long-life gas cooled reactors with exit temperatures of about 2500 K or higher must be developed. Four types of nuclear reactors which have the potential of achieving this goal are the NERVA-type solid core reactor, the colloid core (rotating fluidized bed) reactor, the 'light bulb' gas core reactor, and the 'coaxial flow' gas core reactor. Research programs aimed at developing these reactors have progressed rapidly in recent years so that prototype power reactors could be operating by 1980. Three types of power plant systems which use these reactors have been analyzed to determine the operating characteristics, critical parameters and performance of these power plants. Overall thermal efficiencies as high as 80% are projected, using an MHD turbine-compressor cycle with steam bottoming, and slightly lower efficiencies are projected for an MHD motor-compressor cycle.
Nuclear-electric magnetohydrodynamic propulsion for submarine. Master's thesis
Bednarczyk, A.A.
1989-05-01
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.
Parker Problem in Hall Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Shivamoggi, Bhimsen
2010-11-01
Parker problem in Hall magnetohydrodynamics (MHD) is considered [1]. Poloidal shear into the toroidal flow generated by the Hall effect is incorporated. This is found to lead to a triple deck structure for the Parker problem in Hall MHD, with the magnetic field falling off in the intermediate Hall- resistive region more steeply (like 1/x^3) than that (like 1/x) in the outer ideal MHD region.[1] B. K. Shivamoggi: Phys. Plasmas 16, 052111, (2009).
Multimegawatt NEP with vapor core reactor MHD
NASA Astrophysics Data System (ADS)
Smith, Blair; Knight, Travis; Anghaie, Samim
2002-01-01
Efforts at the Innovative Nuclear Space Power and Propulsion Institute have assessed the feasibility of combining gaseous or vapor core reactors with magnetohydrodynamic power generators to provide extremely high quality, high density, and low specific mass electrical power for space applications. Innovative shielding strategies are employed to maintain an effective but relatively low mass shield, which is the most dominating part of multi-megawatt space power systems. The fission driven magnetohydrodynamic generator produces tens of kilowatt DC power at specific mass of less than 0.5 kg/kW for the total power system. The MHD output with minor conditioning is coupled to magnetoplasmadynamic thruster to achieve an overall NEP system specific mass of less than 1.0 kg/kW for power levels above 20 MWe. Few other concepts would allow comparable ensuing payload savings and flexible mission abort options for manned flights to Mars for example. .
Coal-gasification/MHD/steam-turbine combined-cycle (GMS) power generation
NASA Astrophysics Data System (ADS)
Lytle, J. M.; Marchant, D. D.
1980-11-01
Advantages of a clean fuel system are presented and include the elimination of mineral matter or slag from all components other than the coal gasifier and gas cleanup system; reduced wear and corrosion on components; and increased seed recovery resulting from reduced exposure of seed to mineral matter or slag. Efficiencies in some specific GMS power plants were shown to be higher than for a comparably sized coal burning MHD power plant. The use of energy from the MHD exhaust gas to gasify coal (rather than the typical approach of burning part of the coal) results in these higher efficiencies.
MHD generators as pulse power sources for arc-driven railguns
Esposito, N.; Raugi, M.; Tellini, A.
1995-01-01
In this paper the performances of an electromagnetic launch system constituted by an arc driven railgun powered by a MHD generator are investigated. A small bore plasma driven railgun for fusion fuel pellet injection is examined considering as pulse power source a MHD generator having characteristics taken from operating devices. The analysis of the railgun and generator has been carried out by means of a lumped parameter equivalent network model that takes into account drag force and ablation effects and allowing the evaluation of the main electrical and thermodynamic quantity distributions of the plasma arc.
Closed Cycle Magnetohydrodynamic Nuclear Space Power Generation Using Helium/Xenon Working Plasma
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Harada, N.
2005-01-01
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.
Seyler, C. E.; Martin, M. R.
2011-01-15
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.
Solar-Driven Liquid-Metal MHD Generator
NASA Technical Reports Server (NTRS)
Hohl, F.; Lee, J. H.
1982-01-01
Liquid-metal magnetohydrodynamic (MHD) power generator with solar oven as its heat source has potential to produce electric power in space and on Earth at high efficiency. Generator focuses radiation from Sun to heat driving gas that pushes liquid metal past magnetic coil. Power is extracted directly from electric currents set up in conducting liquid. Using solar energy as fuel can save considerable costs and payload weight, compared to previous systems.
Not Available
1981-11-01
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)
Energy decay laws in strongly anisotropic magnetohydrodynamic turbulence.
Bigot, Barbara; Galtier, Sbastien; Politano, Hlne
2008-02-22
We investigate the influence of a uniform magnetic field B(0)=B(0)e( parallel) on energy decay laws in incompressible magnetohydrodynamic (MHD) turbulence. The nonlinear transfer reduction along B(0) is included in a model that distinguishes parallel and perpendicular directions, following a phenomenology of Kraichnan. We predict a slowing down of the energy decay due to anisotropy in the limit of strong B(0), with distinct power laws for energy decay of shear- and pseudo-Alfvn waves. Numerical results from the kinetic equations of Alfvn wave turbulence recover these predictions, and MHD numerical results clearly tend to follow them in the lowest perpendicular planes. PMID:18352557
An innovative demonstration of high power density in a compact MDH (magnetohydrodynamic) generator
NASA Astrophysics Data System (ADS)
Schmidt, H. J.; Lineberry, J. T.; Chapman, J. N.
1990-06-01
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.
H2OTSTUF: Appropriate Operating Regimes for Magnetohydrodynamic Augmentation
NASA Technical Reports Server (NTRS)
Jones, Jonathan E.; Hawk, Clark W.
1998-01-01
A trade study of magnetohydrodynamic (MHD) augmented propulsion reveals a unique operating regime at lower thrust levels. Substantial mass savings are realized over conventional chemical, solar, and electrical propulsion concepts when MHD augmentation is used to obtain optimal I(sub sp). However, trip times for the most conservative estimates of power plant specific impulse and accelerator efficiency may be prohibitively long. Quasi-one-dimensional calculations show that a solar or nuclear thermal system augmented by MHD can provide competitive performance while utilizing a diverse range of propellants including water, which is available from the Space Shuttle, the Moon, asteroids, and various moons and planets within our solar system. The use of in-situ propellants will reduce costs of space operations as well as enable human exploration of our Solar System. The following conclusions can be drawn from the results of the mission trade study: (1) There exists a maximum thrust or mass flow rate above which MHD augmentation increases the initial mass in low earth orbit (LEO); (2) Mass saving of over 50% can be realized for unique combination of solar/MHD systems; (3) Trip times for systems utilizing current power supply technology may be prohibitively long. Theoretical predictions of MHD performance for in space propulsion systems show that improved efficiencies can reduce trip times to acceptable levels; (4) Long trip times indicative of low thrust systems can be shortened by an increase in the MHD accelerator efficiency or a decrease in the specific mass of the power supply and power processing unit; and (5) As for all propulsion concepts, missions with larger (Delta)v's benefit more from the increased specific impulse resulting from MHD augmentation. Using a quasi-one-dimensional analysis, the required operating conditions for a MHD accelerator to reach acceptable efficiencies are outlined. This analysis shows that substantial non-equilibrium ionization is desirable.
NASA Technical Reports Server (NTRS)
Smith, J. M.; Nichols, L. D.
1977-01-01
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.
Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Hypersonic Airbreathing Engines
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Cole, J. W.; Bityurin, V. A.; Lineberry, J. T.
2000-01-01
The prospects for realizing a magnetohydrodynamic (MHD) bypass hypersonic airbreathing engine are examined from the standpoint of fundamental thermodynamic feasibility. The MHD-bypass engine, first proposed as part of the Russian AJAX vehicle concept, is based on the idea of redistributing energy between various stages of the propulsion system flow train. The system uses an MHD generator to extract a portion of the aerodynamic heating energy from the inlet and an MHD accelerator to reintroduce this power as kinetic energy in the exhaust stream. In this way, the combustor entrance Mach number can be limited to a specified value even as the flight Mach number increases. Thus, the fuel and air can be efficiently mixed and burned within a practical combustor length, and the flight Mach number operating envelope can be extended. In this paper, we quantitatively assess the performance potential and scientific feasibility of MHD-bypass engines using a simplified thermodynamic analysis. This cycle analysis, based on a thermally and calorically perfect gas, incorporates a coupled MHD generator-accelerator system and accounts for aerodynamic losses and thermodynamic process efficiencies in the various engin components. It is found that the flight Mach number range can be significantly extended; however, overall performance is hampered by non-isentropic losses in the MHD devices.
Performance calculations for 200-1000 MWe MHD/steam power plants
NASA Astrophysics Data System (ADS)
Staiger, P. J.
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.
Performance calculations for 200-1000 MWe MHD/steam power plants
NASA Technical Reports Server (NTRS)
Staiger, P. J.
1981-01-01
The effects of MHD generator length, level of oxygen enrichment, and oxygen production power on the performance of MHD/steam power plants ranging from 200 to 1000 MW in electrical output are investigated. The plants considered use oxygen enriched combustion air preheated to 1100 F. Both plants in which the MHD generator is cooled with low temperature and pressure boiler feedwater and plants in which the generator is cooled with high temperature and pressure boiler feedwater are considered. For plants using low temperature boiler feedwater for generator cooling the maximum thermodynamic efficiency is obtained with shorter generators and a lower level of oxygen enrichment compared to plants using high temperature boiler feedwater for generator cooling. The generator length at which the maximum plant efficiency occurs increases with power plant size for plants with a generator cooled by low temperature feedwater. Also shown is the relationship of the magnet stored energy requirement of the generator length and the power plant performance. Possible cost/performance tradeoffs between magnet cost and plant performance are indicated.
Extended magnetohydrodynamics with embedded particle-in-cell simulation of Ganymede's magnetosphere
NASA Astrophysics Data System (ADS)
Tóth, Gábor; Jia, Xianzhe; Markidis, Stefano; Peng, Ivy Bo; Chen, Yuxi; Daldorff, Lars K. S.; Tenishev, Valeriy M.; Borovikov, Dmitry; Haiducek, John D.; Gombosi, Tamas I.; Glocer, Alex; Dorelli, John C.
2016-02-01
We have recently developed a new modeling capability to embed the implicit particle-in-cell (PIC) model iPIC3D into the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme magnetohydrodynamic (MHD) model. The MHD with embedded PIC domains (MHD-EPIC) algorithm is a two-way coupled kinetic-fluid model. As one of the very first applications of the MHD-EPIC algorithm, we simulate the interaction between Jupiter's magnetospheric plasma and Ganymede's magnetosphere. We compare the MHD-EPIC simulations with pure Hall MHD simulations and compare both model results with Galileo observations to assess the importance of kinetic effects in controlling the configuration and dynamics of Ganymede's magnetosphere. We find that the Hall MHD and MHD-EPIC solutions are qualitatively similar, but there are significant quantitative differences. In particular, the density and pressure inside the magnetosphere show different distributions. For our baseline grid resolution the PIC solution is more dynamic than the Hall MHD simulation and it compares significantly better with the Galileo magnetic measurements than the Hall MHD solution. The power spectra of the observed and simulated magnetic field fluctuations agree extremely well for the MHD-EPIC model. The MHD-EPIC simulation also produced a few flux transfer events (FTEs) that have magnetic signatures very similar to an observed event. The simulation shows that the FTEs often exhibit complex 3-D structures with their orientations changing substantially between the equatorial plane and the Galileo trajectory, which explains the magnetic signatures observed during the magnetopause crossings. The computational cost of the MHD-EPIC simulation was only about 4 times more than that of the Hall MHD simulation.
Optimization of the oxidant supply system for combined cycle MHD power plants
NASA Technical Reports Server (NTRS)
Juhasz, A. J.
1982-01-01
An in-depth study was conducted to determine what, if any, improvements could be made on the oxidant supply system for combined cycle MHD power plants which could be reflected in higher thermal efficiency and a reduction in the cost of electricity, COE. A systematic analysis of air separation process varitions which showed that the specific energy consumption could be minimized when the product stream oxygen concentration is about 70 mole percent was conducted. The use of advanced air compressors, having variable speed and guide vane position control, results in additional power savings. The study also led to the conceptual design of a new air separation process, sized for a 500 MW sub e MHD plant, referred to a internal compression is discussed. In addition to its lower overall energy consumption, potential capital cost savings were identified for air separation plants using this process when constructed in a single large air separation train rather than multiple parallel trains, typical of conventional practice.
The infinite interface limit of multiple-region relaxed magnetohydrodynamics
Dennis, G. R.; Dewar, R. L.; Hole, M. J.; Hudson, S. R.
2013-03-15
We show the stepped-pressure equilibria that are obtained from a generalization of Taylor relaxation known as multi-region, relaxed magnetohydrodynamics (MRXMHD) are also generalizations of ideal magnetohydrodynamics (ideal MHD). We show this by proving that as the number of plasma regions becomes infinite, MRXMHD reduces to ideal MHD. Numerical convergence studies illustrating this limit are presented.
Results from conceptual design study of potential early commercial MHD/steam power plants
NASA Technical Reports Server (NTRS)
Hals, F.; Kessler, R.; Swallom, D.; Westra, L.; Zar, J.; Morgan, W.; Bozzuto, C.
1981-01-01
This paper presents conceptual design information for a potential early MHD power plant developed in the second phase of a joint study of such plants. Conceptual designs of plant components and equipment with performance, operational characteristics and costs are reported on. Plant economics and overall performance including full and part load operation are reviewed. Environmental aspects and the methods incorporated in plant design for emission control of sulfur and nitrogen oxides are reviewed. Results from reliability/availability analysis conducted are also included.
Scale-locality of magnetohydrodynamic turbulence
Aluie, Hussein; Eyink, Gregory L
2009-01-01
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.
Closed cycle MHD power generation experiments in the NASA Lewis Facility
NASA Technical Reports Server (NTRS)
Sovie, R. J.; Nichols, L. D.
1974-01-01
Many modifications were made in the MHD facility. These include a redesign of the MHD duct interior, addition of mixing bars, increased electrical isolation of all the high temperature components from each other and from ground, and experimentation with various cesium seed vaporization and injection techniques. With the exception of the cesium system which needs further improvement the above modifications were quite successful and resulted in improvements in generator performance. The facility was run for a total of 400 hours in the past year, with 70 hours of this operation at temperatures of 2000 K or more with hot generator walls. With the exception of replacing one cracked brick in the MHD channel no repairs were required in the high temperature loop components for the duration of these tests. Uniform Faraday and Hall voltage profiles were obtained and the Faraday open circuit voltage varied from 90 to 100 percent of the ideal uBh. The magnitudes of the measured parameters are: Faraday open circuit voltage approximately 70 V, total Faraday current approximately 20 A, Hall voltage approximately 250 V, power output approximately 300 W, and power density .036 W/cu cm.
Methods of reducing energy consumption of the oxidant supply system for MHD/steam power plants
NASA Technical Reports Server (NTRS)
Juhasz, A. J.
1983-01-01
An in-depth study was conducted to identify possible improvements to the oxidant supply system for combined cycle MHD power plants which would lead to higher thermal efficiency and reduction in the cost of electricity, COE. Results showed that the oxidant system energy consumption could be minimized when the process was designed to deliver a product O2 concentration of 70 mole percent. The study also led to the development of a new air separation process, referred to as 'liquid pumping and internal compression'. MHD system performance calculations show that the new process would permit an increase in plant thermal efficiency of 0.6 percent while allowing more favorable tradeoffs between magnetic energy and oxidant system capacity requirements.
Methods of reducing energy consumption of the oxidant supply system for MHD/steam power plants
NASA Technical Reports Server (NTRS)
Juhasz, A. J.
1983-01-01
An in-depth study was conducted to identify possible improvements to the oxidant supply system for combined cycle MHD power plants which would lead to higher thermal efficiency and reduction in the cost of electricity, COE. Results showed that the oxidant system energy consumption could be minimized when the process was designed to deliver a product O2 concentration of 70 mole percent. The study also led to the development of a new air separation process, referred to as liquid pumping and internal compression. MHD system performance calculations show that the new process would permit an increase in plant thermal efficiency of 0.6 percent while allowing more favorable tradeoffs between magnetic energy and oxidant system capacity requirements.
Advanced fusion MHD power conversion using the CFAR (compact fusion advanced Rankine) cycle concept
Hoffman, M.A.; Campbell, R.; Logan, B.G.; Lawrence Livermore National Lab., CA )
1988-10-01
The CFAR (compact fusion advanced Rankine) cycle concept for a tokamak reactor involves the use of a high-temperature Rankine cycle in combination with microwave superheaters and nonequilibrium MHD disk generators to obtain a compact, low-capital-cost power conversion system which fits almost entirely within the reactor vault. The significant savings in the balance-of-plant costs are expected to result in much lower 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.
NASA Astrophysics Data System (ADS)
Erdlyi, R.
2007-07-01
The heating of solar atmosphere from chromosphere to corona is one of the key fundamental and yet unresolved questions of modern space and plasma physics. In spite of the multi-fold efforts spanning over half a century including the many superb technological advances and theoretical developments (both analytical and computational) the unveiling of the subtle of coronal heating still remains an exciting job for the 21st century! In the present paper I review the various popular heating mechanisms put forward in the existing extensive literature. The heating processes are, somewhat arbitrarily, classified as hydrodynamic (HD), magnetohydrodynamic (MHD) or kinetic based on the model medium. These mechanisms are further divided based on the time scales of the ultimate dissipation involved (i.e. AC and DC heating, turbulent heating). In particular, attention is paid to discuss shock dissipation, Landau damping, mode coupling, resonant absorption, phase mixing, and, reconnection. Finally, I briefly review the various observational consequences of the many proposed heating mechanisms and confront them with high-resolution ground-based and satellite data currently available.
Three-Dimensional Numerical Modeling of Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Turner, M. W.; Hawk, C. W.; Litchford, R. J.
2009-01-01
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.
Potential vorticity in magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Webb, G. M.; Mace, R. L.
2015-01-01
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.
Computational fusion magnetohydrodynamics
Grimm, R.C.
1984-01-01
Simple magnetohydrodynamic models provide the framework for much of our understanding of the macroscopic behavior of magnetically confined laboratory plasmas. In even the simplest of models, however, the many different time and spatial scales, the multidimensionality, and the nonlinearity of the equations make finding solutions difficult. In realistic geometries obtaining quantitative results to aid our understanding, to interpret experiment, and to design new devices, involves the development of large scale numerical codes. During the past decade considerable effort has been extended in the fusion community to develop equilibrium, linear stability, and nonlinear time evolution codes in two and three dimensions, some of which have had a considerable impact on the fusion program. An overview of the various types of codes and numerical methods is given. Emphasis is on the spectrum of linear perturbations and ideal MHD stability, boundary layer methods and resistive MHD stability, and modeling of nonlinear, time evolution resistive MHD phenomena in tokamak configurations.
Multi-region relaxed magnetohydrodynamics with flow
Dennis, G. R. Dewar, R. L.; Hole, M. J.; Hudson, S. R.
2014-04-15
We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes plasma flow. This new model is a generalization of Woltjer's model of relaxed magnetohydrodynamics equilibria with flow. We prove that as the number of plasma regions becomes infinite, our extension of MRxMHD reduces to ideal MHD with flow. We also prove that some solutions to MRxMHD with flow are not time-independent in the laboratory frame, and instead have 3D structure which rotates in the toroidal direction with fixed angular velocity. This capability gives MRxMHD potential application to describing rotating 3D MHD structures such as 'snakes' and long-lived modes.
Magneto-Hydrodynamics Based Microfluidics
Qian, Shizhi; Bau, Haim H.
2009-01-01
In microfluidic devices, it is necessary to propel samples and reagents from one part of the device to another, stir fluids, and detect the presence of chemical and biological targets. Given the small size of these devices, the above tasks are far from trivial. Magnetohydrodynamics (MHD) offers an elegant means to control fluid flow in microdevices without a need for mechanical components. In this paper, we review the theory of MHD for low conductivity fluids and describe various applications of MHD such as fluid pumping, flow control in fluidic networks, fluid stirring and mixing, circular liquid chromatography, thermal reactors, and microcoolers. PMID:20046890
[Magnetohydrodynamic effects during blood movement].
Kizilova, N N; Regirer, S A
1991-01-01
Theoretical investigations of magnetohydrodynamic (MHD) effects in flowing blood are briefly reviewed in their formal and physiological aspects. It is shown that the great part of published works contain serious errors, as well as groundless practical propositions without any satisfactory explanation. PMID:1854824
Parabolized Navier-Stokes Code for Computing Magneto-Hydrodynamic Flowfields
NASA Technical Reports Server (NTRS)
Mehta, Unmeel B. (Technical Monitor); Tannehill, J. C.
2003-01-01
This report consists of two published papers, 'Computation of Magnetohydrodynamic Flows Using an Iterative PNS Algorithm' and 'Numerical Simulation of Turbulent MHD Flows Using an Iterative PNS Algorithm'.
BOOK REVIEW: Nonlinear Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Shafranov, V.
1998-08-01
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
MHD advanced power train. Phase 1, Final report: Volume 2, Development program plan
Jones, A.R.
1985-08-01
Two scale-up steps are required before the 200 MW(e) power plant could be designed and constructed. The development program plan is designed to meet these 3 needed program elements: (a) design and demonstration test of a 50 MW(t) power train that verifies channel life; (b) design, development, and demonstration of an advanced power train in a 250 MW(t) plant facility; and (c) development of technology for advanced MHD generators that are economic of magnet warm bore, reliable for at least 4000 hours operation, and are amenable to automated production to meet the low cost goal. An implicit program element, Base Technology, provides support to these 3 elements. The overall program will require 11 years and is estimated to cost $278 million in 1984 dollars.
Diagnostic development and support of MHD test facilities
Not Available
1990-01-01
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for Magnetohydrodynamics (MHD) power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for Heat Recovery/Seed Recovery support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with DIAL's computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel will also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs. 9 figs., 1 tab.
Diagnostic development and support of MHD test facilities
NASA Astrophysics Data System (ADS)
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 support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with DIAL's computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel will also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products, and services applicable to their needs.
Preliminary results in the NASA Lewis H2-O2 combustion MHD experiment
NASA Technical Reports Server (NTRS)
Smith, J. M.
1979-01-01
MHD (magnetohydrodynamic) power generation experiments were carried out in the NASA Lewis Research Center cesium-seeded H2-O2 combustion facility. This facility uses a neon-cooled cryomagnet capable of producing magnetic fields in excess of 5 tesla. The effects of power takeoff location, generator loading, B-field strength, and electrode breakdown on generator performance are discussed. The experimental data is compared to a theory based on one-dimensional flow with heat transfer, friction, and voltage drops.
Study of multi-phase flow characteristics in an MHD power train
Chang, S.L.; Lottes, S.A.; Bouillard, J.X.; Petrick, M.
1993-08-01
Computer simulation was used to predict two-phase flow processes in the CDIF MHD power train system. The predictions were used to evaluate the effects of operating and design parameters on the performance of the system and a parametric evaluation provides information to enhance the performance of the system. Major components of the system under investigation are the two-stage combustor, the converging/diverging nozzle, the supersonic MHD channel, and the diffuser. Flow in each component was simulated using a computer code. Integrating the computer codes, the two-phase flow processes in the system was calculated. Recently, the computer codes were used to investigate problems of nozzle erosion and the non-uniform iron oxide coverage on the cathode wall in the channel. A limited parametric study was conducted. The results indicated that (1) among the three nozzle geometries under investigation a {number_sign}5 nozzle has the smoothest flow development in the nozzle and has the lowest droplet deposition on wall and (2) smaller particle size and lower injection velocity tend to disperse the iron oxide particles more uniformly in the nozzle.
Temporal intermittency of energy dissipation in magnetohydrodynamic turbulence.
Zhdankin, Vladimir; Uzdensky, Dmitri A; Boldyrev, Stanislav
2015-02-13
Energy dissipation in magnetohydrodynamic (MHD) turbulence is known to be highly intermittent in space, being concentrated in sheetlike coherent structures. Much less is known about intermittency in time, another fundamental aspect of turbulence which has great importance for observations of solar flares and other space or astrophysical phenomena. In this Letter, we investigate the temporal intermittency of energy dissipation in numerical simulations of MHD turbulence. We consider four-dimensional spatiotemporal structures, "flare events," responsible for a large fraction of the energy dissipation. We find that although the flare events are often highly complex, they exhibit robust power-law distributions and scaling relations. We find that the probability distribution of dissipated energy has a power-law index close to α≈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
Nakamura, Masanori; Garofalo, David; Meier, David L. E-mail: david.a.garofalo@jpl.nasa.go
2010-10-01
This is the first in a series of papers that introduces a new paradigm for understanding the jet in M87: a collimated relativistic flow in which strong magnetic fields play a dominant dynamical role. Here, we focus on the flow downstream of HST-1-an essentially stationary flaring feature that ejects trails of superluminal components. We propose that these components are quad relativistic magnetohydrodynamic shock fronts (forward/reverse fast and slow modes) in a narrow jet with a helically twisted magnetic structure. And we demonstrate the properties of such shocks with simple one-dimensional numerical simulations. Quasi-periodic ejections of similar component trails may be responsible for the M87 jet substructures observed further downstream on 10{sup 2}-10{sup 3} pc scales. This new paradigm requires the assimilation of some new concepts into the astrophysical jet community, particularly the behavior of slow/fast-mode waves/shocks and of current-driven helical kink instabilities. However, the prospects of these ideas applying to a large number of other jet systems may make this worth the effort.
Multi-region relaxed magnetohydrodynamics with anisotropy and flow
Dennis, G. R. Dewar, R. L.; Hole, M. J.; Hudson, S. R.
2014-07-15
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.
Plasma relaxation and topological aspects in Hall magnetohydrodynamics
Shivamoggi, B. K.
2012-07-15
Parker's formulation of isotopological plasma relaxation process in magnetohydrodynamics (MHD) is extended to Hall MHD. The torsion coefficient {alpha} in the Hall MHD Beltrami condition turns out now to be proportional to the potential vorticity. The Hall MHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics if the Hall MHD Lagrange multiplier {beta} is taken to be proportional to the potential vorticity as well. The winding pattern of the magnetic field lines in Hall MHD then appears to evolve in the same way as potential vorticity lines in 2D hydrodynamics.
Retrofit of a coal-fired open-cycle liquid-metal MHD to steam power plants
Pierson, E.S.; Herman, H.; Petrick, M.; Grammel, S.J.; Dubey, G.
1981-01-01
The application of the new, coal-fired open-cycle liquid-metal MHD (OC-LMMHD) energy-conversion system to the retrofit of an existing, oil- or gas-fired conventional steam power plant is evaluated. The criteria used to evaluate the retrofit are the net plant efficiency and the cost benefit relative to other options. 7 refs.
NASA Astrophysics Data System (ADS)
Dewar, R. L.; Mills, R.; Hole, M. J.
2009-05-01
The celebration of Allan Kaufman's 80th birthday was an occasion to reflect on a career that has stimulated the mutual exchange of ideas (or memes in the terminology of Richard Dawkins) between many researchers. This paper will revisit a meme Allan encountered in his early career in magnetohydrodynamics, the continuation of a magnetohydrodynamic mode through a singularity, and will also mention other problems where Allan's work has had a powerful cross-fertilizing effect in plasma physics and other areas of physics and mathematics. To resolve the continuation problem we regularize the Newcomb equation, solve it in terms of Legendre functions of imaginary argument, and define the small weak solutions of the Newcomb equation as generalized functions in the manner of Lighthill, i.e. via a limiting sequence of analytic functions that connect smoothly across the singularity.
NASA Technical Reports Server (NTRS)
Staiger, P. J.; Penko, P. F.
1982-01-01
The conceptual design study of a potential early commercial MHD power plant (CSPEC) is described and the results are summarized. Each of two contractors did a conceptual design of an approximtely 1000 MWe open-cycle MHD/steam plant with oxygen enriched combustion air preheated to an intermediate temperatue in a metallic heat exchanger. The contractors were close in their overall plant efficiency estimates but differed in their capital cost and cost of electricity estimates, primarily because of differences in balance-of-plant material, contingency, and operating and maintenance cost estimates. One contractor concluded that its MHD plant design compared favorably in cost of electricity with conventional coal-fired steam plants. The other contractor is making such a comparison as part of a follow-on study. Each contractor did a preliminary investigation of part-load performance and plant availability. The results of NASA studies investigating the effect of plant size and oxidizer preheat temperature on the performance of CSPEC-type MHD plants are also described. The efficiency of a 1000 MWe plant is about three points higher than of a 200 MWe plant. Preheating to 1600 F gives an efficiency about one and one-half points higher than preheating to 800 F for all plant sizes. For each plant size and preheat temperature there is an oxidizer enrichment level and MHD generator length that gives the highest plant efficiency.
Results of closed cycle MHD power generation test with a helium-cesium working fluid
NASA Technical Reports Server (NTRS)
Sovie, R. J.
1977-01-01
The cross sectional dimensions of the MHD channel in the NASA Lewis closed loop facility were reduced to 3.8 x 11.4 cm. Tests were run in this channel using a helium-cesium working fluid at stagnation pressures of 160,000 n/M2, stagnation temperatures of 2000-2060 K and an entrance Mach number of 0.36. In these tests Faraday open circuit voltages of 200 V were measured which correspond to a Faraday field of 1750 V/M. Power generation tests were run for different groups of electrode configurations and channel lengths. Hall fields up to 1450 V/M were generated. Power extraction per electrode of 183 W and power densities of 1.7 MW/M3 were obtained. A total power output of 2 kW was generated for tests with 14 electrodes. The power densities obtained in this channel represent a factor of 3 improvement over those previously reported for the M = 0.2 channel.
Ideal MHD stability of a spherical tokamak power plant and a component test facility
NASA Astrophysics Data System (ADS)
Hole, M. J.; Wilson, H. R.; Abeysuriya, R.; Larson, J. W.
2010-12-01
We have investigated ideal MHD stability of two advanced spherical tokamak confinement concepts: the spherical tokamak power plant (STPP), a 3 GW concept fusion power plasma producing 1 GW of electric power, and the component test facility (CTF), a concept designed for in situ materials testing for ITER and beyond. Detailed stability studies for toroidal mode number n = 1, 2, 3 displacements are presented as a function of conformal wall radius Rw and on-axis safety factor q0. For the STPP marginal stability scans held the current profile fixed, but varied the total plasma current. For the CTF we have extended and parallelized earlier marginal stability scans to scan over both the plasma beta and q0 by varying the current profile to preserve the total plasma current. These confirm that both concepts are stable provided that the wall is sufficiently close and q0 sufficiently large (q0 > 2.8 for the power plant and q0 > 2.1 for the CTF). Both power plant and CTF configurations are found to be ballooning stable.
Isogeometric analysis in reduced magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Ratnani, A.; Sonnendrcker, E.
2012-01-01
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 Bzier splines approach of Czarny and Huysmans (2008 J. Comput. Phys. 227 7423-45).
Method for manufacturing magnetohydrodynamic electrodes
Killpatrick, D.H.; Thresh, H.R.
1980-06-24
A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator is described comprising the steps of preparing a billet having a core of a first metal, a tubular sleeve of a second metal, and an outer sheath of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MHD channel frame. The method forms a bond between the first metal of the core and the second metal of the sleeve strong enough to withstand a hot and corrosive environment.
Viscosity and Vorticity in Reduced Magneto-Hydrodynamics
Joseph, Ilon
2015-08-12
Magneto-hydrodynamics (MHD) critically relies on viscous forces in order for an accurate determination of the electric eld. For each charged particle species, the Braginskii viscous tensor for a magnetized plasma has the decomposition into matrices with special symmetries.
Channel-wall limitations in the magnetohydrodynamic induction generator
NASA Technical Reports Server (NTRS)
Jackson, W. D.; Pierson, E. S.
1969-01-01
Discussion of magnetohydrodynamic induction generator examines the machine in detail and materials problems influencing its design. The higher upper-temperature limit of the MHD system promises to be more efficient than present turbine systems for generating electricity.
Magnetohydrodynamically generated velocities in confined plasma
Morales, Jorge A. Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.
2015-04-15
We investigate by numerical simulation the rotational flows in a toroid confining a conducting magnetofluid in which a current is driven by the application of externally supported electric and magnetic fields. The computation involves no microscopic instabilities and is purely magnetohydrodynamic (MHD). We show how the properties and intensity of the rotations are regulated by dimensionless numbers (Lundquist and viscous Lundquist) that contain the resistivity and viscosity of the magnetofluid. At the magnetohydrodynamic level (uniform mass density and incompressible magnetofluids), rotational flows appear in toroidal, driven MHD. The evolution of these flows with the transport coefficients, geometry, and safety factor are described.
Magnetohydrodynamically generated velocities in confined plasma
NASA Astrophysics Data System (ADS)
Morales, Jorge A.; Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.
2015-04-01
We investigate by numerical simulation the rotational flows in a toroid confining a conducting magnetofluid in which a current is driven by the application of externally supported electric and magnetic fields. The computation involves no microscopic instabilities and is purely magnetohydrodynamic (MHD). We show how the properties and intensity of the rotations are regulated by dimensionless numbers (Lundquist and viscous Lundquist) that contain the resistivity and viscosity of the magnetofluid. At the magnetohydrodynamic level (uniform mass density and incompressible magnetofluids), rotational flows appear in toroidal, driven MHD. The evolution of these flows with the transport coefficients, geometry, and safety factor are described.
SPECTRA OF STRONG MAGNETOHYDRODYNAMIC TURBULENCE FROM HIGH-RESOLUTION SIMULATIONS
Beresnyak, Andrey
2014-04-01
Magnetohydrodynamic (MHD) turbulence is present in a variety of solar and astrophysical environments. Solar wind fluctuations with frequencies lower than 0.1Hz are believed to be mostly governed by Alfvnic turbulence with particle transport depending on the power spectrum and the anisotropy of such turbulence. Recently, conflicting spectral slopes for the inertial range of MHD turbulence have been reported by different groups. Spectral shapes from earlier simulations showed that MHD turbulence is less scale-local compared with hydrodynamic turbulence. This is why higher-resolution simulations, and careful and rigorous numerical analysis is especially needed for the MHD case. In this Letter, we present two groups of simulations with resolution up to 4096{sup 3}, which are numerically well-resolved and have been analyzed with an exact and well-tested method of scaling study. Our results from both simulation groups indicate that the asymptotic power spectral slope for all energy-related quantities, such as total energy and residual energy, is around 1.7, close to Kolmogorov's 5/3. This suggests that residual energy is a constant fraction of the total energy and that in the asymptotic regime of Alfvnic turbulence magnetic and kinetic spectra have the same scaling. The 1.5 slope for energy and the 2 slope for residual energy, which have been suggested earlier, are incompatible with our numerics.
Remarkable connections between extended magnetohydrodynamics models
NASA Astrophysics Data System (ADS)
Lingam, M.; Morrison, P. J.; Miloshevich, G.
2015-07-01
Through the use of suitable variable transformations, the commonality of all extended magnetohydrodynamics (MHD) models is established. Remarkable correspondences between the Poisson brackets of inertialess Hall MHD and inertial MHD (which has electron inertia, but not the Hall drift) and extended MHD (which has both effects) are established. The helicities (two in all) for each of these models are obtained through these correspondences. The commonality of all the extended MHD models is traced to the existence of two Lie-dragged 2-forms, which are closely associated with the canonical momenta of the two underlying species. The Lie-dragging of these 2-forms by suitable velocities also leads to the correct equations of motion. The Hall MHD Poisson bracket is analyzed in detail, the Jacobi identity is verified through a detailed proof, and this proof ensures the Jacobi identity for the Poisson brackets of all the models.
Chang, S.L.; Lottes, S.A.; Petrick, M.
1994-06-01
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.
Gas-phase magnetohydrodynamic disk accelerator
NASA Astrophysics Data System (ADS)
Pozdnyakov, G. A.
2007-06-01
A pulsed gas-phase magnetohydrodynamic (MHD) disk accelerator with a radial initial gas flow and radial electric current direction is described. Some working regime parameters and characteristics of the accelerated natural gas flow are reported. MHD accelerators of this type can be used for the investigation of chemical kinetics. Another promising application is related to the development of supersonic gas-phase endothermal chemical reactors with gasdynamic control.
Lattice Boltzmann model for simulation of magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Chen, Shiyi; Chen, Hudong; Martinez, Daniel; Matthaeus, William
1991-01-01
A numerical method, based on a discrete Boltzmann equation, is presented for solving the equations of magnetohydrodynamics (MHD). The algorithm provides advantages similar to the cellular automaton method in that it is local and easily adapted to parallel computing environments. Because of much lower noise levels and less stringent requirements on lattice size, the method appears to be more competitive with traditional solution methods. Examples show that the model accurately reproduces both linear and nonlinear MHD phenomena.
Relabeling symmetries in hydrodynamics and magnetohydrodynamics
Padhye, N.; Morrison, P.J.
1996-04-01
Lagrangian symmetries and concomitant generalized Bianchi identities associated with the relabeling of fluid elements are found for hydrodynamics and magnetohydrodynamics (MHD). In hydrodynamics relabeling results in Ertel`s theorem of conservation of potential vorticity, while in MHD it yields the conservation of cross helicity. The symmetries of the reduction from Lagrangian (material) to Eulerian variables are used to construct the Casimir invariants of the Hamiltonian formalism.
Wave turbulence in incompressible Hall magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Galtier, Sébastien
We investigate the steepening of the magnetic fluctuation power law spectra observed in the inner Solar wind for frequencies higher than 0.5 Hz. This high frequency part of the spectrum may be attributed to dispersive nonlinear processes. In that context, the long-time behavior of weakly interacting waves is examined in the framework of three-dimensional incompressible Hall magnetohydrodynamic (MHD) turbulence. The Hall term added to the standard MHD equations makes the Alfvén waves dispersive and circularly polarized. We introduce the generalized Elsässer variables and, using a complex helicity decomposition, we derive for three-wave interaction processes the general wave kinetic equations; they describe the nonlinear dynamics of Alfvén, whistler and ion cyclotron wave turbulence in the presence of a strong uniform magnetic field B_0 \\(e}_{Vert) . Hall MHD turbulence is characterized by anisotropies of different strength: (i) for wavenumbers textit{kd}_i {≫} 1 (d_i is the ion inertial length) nonlinear transfers are essentially in the direction perpendicular (⊥) to B_0; (ii) for textit{kd}_i {≪} 1 nonlinear transfers are exclusively in the perpendicular direction; (iii) for textit{kd}_i ˜ 1, a moderate anisotropy is predicted. We show that electron and standard MHD turbulence can be seen as two frequency limits of the present theory but the standard MHD limit is singular; additionally, we analyze in detail the ion MHD turbulence limit. Exact power law solutions of the master wave kinetic equations are given in the small- and large-scale limits for which we have, respectively, the total energy spectra E(k_{⊥},k_{Vert}) ˜ k_{⊥}(-5/2) |k_{Vert}|(-1/2) and E(k_{⊥},k_{Vert}) ˜ k_{⊥}(-2) . An anisotropic phenomenology is developed to describe continuously the different scaling laws of the energy spectrum; one predicts E(k_{⊥},k_{Vert}) ˜ k_{⊥}(-2) |k_{Vert}|(-1/2) (1+k_{⊥}(2d_) i(2)(-1/4)) . Non-local interactions between Alfvén, whistler and ion cyclotron waves are investigated; a non-trivial dynamics exists only when a discrepancy from the equipartition between the large-scale kinetic and magnetic energies happens.
Not Available
1981-11-01
Program accomplishments in a continuing effort to demonstrate the feasibility of direct coal-fired, closed-cycle MHD power generation are reported. This volume contains the following appendices: (A) user's manual for 2-dimensional MHD generator code (2DEM); (B) performance estimates for a nominal 30 MW argon segmented heater; (C) the feedwater cooled Brayton cycle; (D) application of CCMHD in an industrial cogeneration environment; (E) preliminary design for shell and tube primary heat exchanger; and (F) plant efficiency as a function of output power for open and closed cycle MHD power plants. (WHK)
NASA Technical Reports Server (NTRS)
Hals, F. A.
1981-01-01
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.
Conceptual design of a coal-fired retrofit liquid-metal MHD power system
Pierson, E.S.; Herman, H.; Petrick, M.
1981-01-01
The desire to develop a coal-fired energy-conversion system with the high efficiencies and moderate temperatures of two-phase-generator liquid-metal MHD (LMMHD) systems led to the open-cycle LMMHD (OC-LMMHD) concept. A liquid metal, most likely copper, that is compatible with combustion gases is used so that the combustion gas can be mixed with the liquid metal to form the two-phase mixture in the LMMHD generator, thereby eliminating the need for a primary heat exchanger. Applications where OC-LMMHD appears to be particularly attractive include central power plants larger than approx. 10 MW(e), retrofit of existing oil- or gas-fired central steam power plants to burn coal, and cogeneration systems requiring high-temperature process heat. The latter two, in particular, benefit from the clean combustion gas stream leaving the copper in the LMMHD system. To explore the technical and economic feasibility of this new LMMHD concept, a conceptual design study of the retrofit of a coal-fired OC-LMMHD topping cycle to a conventional steam plant was selected, and extensive parametric studies carried out to establish the optimum parameter ranges for the retrofit cycle. A conceptual design was developed for the plant and the components with sufficient detail that a cost estimate for the retrofit could be readily made.
Ideal MHD stability of the Component Test Facility and Culham Spherical Tokamak Power Plant
NASA Astrophysics Data System (ADS)
Keating, O.; Wilson, H. R.; Hole, M. J.
2004-11-01
As well as complementing the physics base for ITER, theory and progress in Spherical Tokamak (ST) experiments have prompted design studies into next step ST devices such as the Component Test Facility (CTF) [1], and ST power plants such as the 3GW (fusion) / 1GW (electric) Culham ST Power Plant (STPP) [2]. In this study, low toroidal wave number (n=0,1,2,3) and ballooning (n=∞) ideal MHD stability of the CTF and STPP concepts is addressed: for low n modes scans of growth rate with conformal wall radius and on-axis safety factor q0 are performed, whilst for ballooning modes the proximity to the marginally stable pressure-driven boundaries assessed. Stable equilibria are reported in both configurations, consolidating the viability of the ST line. Time permitting, the effects of toroidal flow will be qualitatively investigated, and the role of fast particles discussed. [1] H. R. Wilson et al, EPS Conf. Plasma Phs., P4-196. 2004. [2] H. R. Wilson et al, in-press, Nuc. Fus. 2004.
Not Available
1981-09-01
This section of the CDER contains background data used in the development of the physical and technical design, as well as plant costs and schedules, presented in the previous sections. Included is a listing and discussion of major issues covering materials, components, systems, and techniques which could influence the final ETF design. Studies have been performed for some of the more significant issues and are presented. Also included are outlines of plans for a performance assurance program and to perform an environmental analysis for the chosen site. Detail design information for the various systems which comprise the ETF design is contained in the System Design Descriptions.
Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device
Haaland, C.M.; Deeds, W.E.
1999-07-13
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.
Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device
Haaland, Carsten M. (Dadeville, AL); Deeds, W. Edward (Knoxville, TN)
1999-01-01
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.
Magnetohydrodynamics in the extreme relativistic limit
NASA Astrophysics Data System (ADS)
Thompson, Christopher; Blaes, Omer
1998-03-01
We present two new formulations of magnetohydrodynamics (MHD), in the limit where the inertia of the charge carriers can be neglected. The first employs Lagrangian coordinates and generalizes Newcomb's formalism to allow for a variable time slicing. It contains an extremely simple prescription for generalizing the action of a relativistic Nambu-Goto string to four dimensions. It is also related by a duality transformation to the action presented by Achterberg. This transformation causes the perturbed and unperturbed Lagrangian coordinates to exchange roles as dynamical fields and background spacetime. Our second formulation introduces massless electrically charged fermions as the current carrying modes, and considers long wavelength perturbations with ?2,k2?<
Magnetohydrodynamic Turbulence and the Geodynamo
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2014-01-01
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.
NASA Technical Reports Server (NTRS)
Hals, F.; Kessler, R.; Swallom, D.; Westra, L.; Zar, J.; Morgan, W.; Bozzuto, C.
1980-01-01
The study deals with different 'moderate technology' entry-level commercial MHD power plants. Two of the reference plants are based on combustion of coal with air preheated in a high-temperature regenerative air heater separately fired with a low-BTU gas produced in a gasifier integrated with the power plant. The third reference plant design is based on the use of oxygen enriched combustion air. Performance calculations show that an overall power plant efficiency of the order of 44% can be reached with the use of oxygen enrichment.
A simulation of the IPS variations from a magnetohydrodynamical simulation
NASA Technical Reports Server (NTRS)
Tappin, S. J.; Dryer, M.; Han, S. M.; Wu, S. T.
1987-01-01
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.
Preliminary analysis of 500 MWt MHD power plant with oxygen enrichment
NASA Astrophysics Data System (ADS)
1980-04-01
An MHD Engineering Test Facility design concept is analyzed. A 500 MWt oxygen enriched MHD topping cycle integrated for combined cycle operation with a 400 MWe steam plant is evaluated. The MHD cycle uses Montana Rosebud coal and air enriched to 35 mole percent oxygen preheated to 1100 F. The steam plant is a 2535 psia/1000 F/1000 F reheat recycle that was scaled down from the Gilbert/Commonwealth Reference Fossil Plant design series. Integration is accomplished by blending the steam generated in the MHD heat recovery system with steam generated by the partial firing of the steam plant boiler to provide the total flow requirement of the turbine. The major MHD and steam plant auxiliaries are driven by steam turbines. When the MHD cycle is taken out of service, the steam plant is capable of stand-alone operation at turbine design throttle flow. This operation requires the full firing of the steam plant boiler. A preliminary feasibility assessment is given, and results on the system thermodynamics, construction scheduling, and capital costs are presented.
Open-cycle magnetohydrodynamic power plant with CO.sub.2 recycling
Berry, Gregory F.
1991-01-01
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.
Global Magnetohydrodynamic Modeling of the Solar Corona
NASA Technical Reports Server (NTRS)
Linker, Jon A.
2001-01-01
This report describes the progress made in the investigation of the solar corona using magnetohydrodynamic (MHD) simulations. Coronal mass ejections (CME) are believed to be the primary cause of nonrecurrent geomagnetic storms and these have been investigated through the use of three-dimensional computer simulation.
Symmetry transforms for ideal magnetohydrodynamics equilibria.
Bogoyavlenskij, Oleg I
2002-11-01
A method for constructing ideal magnetohydrodynamics (MHD) equilibria is introduced. The method consists of the application of symmetry transforms to any known MHD equilibrium [ O. I. Bogoyavlenskij, Phys. Rev. E. 62, 8616, (2000)]. The transforms break the geometrical symmetries of the field-aligned solutions and produce continuous families of the nonsymmetric MHD equilibria. The method of symmetry transforms also allows to obtain MHD equilibria with current sheets and exact solutions with noncollinear vector fields B and V. A model of the nonsymmetric astrophysical jets outside of their accretion disks is developed. The total magnetic and kinetic energy of the jet is finite in any layer c(1)
MHD technology in aluminum casting
Kalinichenko, I.
1984-08-01
The use of MHD technology in aluminum casting is discussed. Associates of the Latvian Academy of Sciences Institute of Physics developed magnetohydrodynamic units for the Siberian plant. A MHD unit made it possible to free five persons from heavy work at the plant. Labor productivity doubled in this section. With the aid of the magnetic field, the alloy silumin is obtained in only three hours. Specialists of the Irkutsk affiliate of the All-Union Scientific Research and Design Institute of the Aluminum, Magnesium and Electrode Industry are convinced that MHD technology has a bright future. However, this will necessitate the development of new MHD technology for different types of casting facilities, with their specific features taken into account.
Survey of MHD plant applications
NASA Technical Reports Server (NTRS)
Lynch, J. J.; Seikel, G. R.; Cutting, J. C.
1979-01-01
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.
Not Available
1992-03-01
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.
NASA Astrophysics Data System (ADS)
Koning, J. M.; Kerbel, G. D.; Marinak, M. M.
2011-10-01
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. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Not Available
1994-07-01
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for magnetohydrodynamic (MHD) power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for Heat Recovery/Seed Recovery (HRSR) support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with DIAL`s computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs.
Shepard, W.S.; Cook, R.L.
1991-12-31
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU) is developing diagnostic instruments for magnetohydrodynamic (MHD) power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for Heat Recovery/Seed Recovery (HRSR) support, are being refined, and new systems to measure temperatures and gas-seed-slag stream characteristics are being developed. To further data acquisition and analysis capabilities, the diagnostic systems are being interfaced with DIAL`S computers. Technical support for the diagnostic needs of the national MHD research effort is being provided. DIAL personnel also cooperate with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs.
Free boundary skin current MHD (magnetohydrodynamic) equilibria
Reusch, M.F.
1988-02-01
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.
Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.
2008-01-01
Over the past several years, efforts have been under way to design and develop an operationally flexible research facility for investigating the use of cross-field MHD accelerators as a potential thrust augmentation device for thermal propulsion systems. The baseline configuration for this high-power experimental facility utilizes a 1.5-MWe multi-gas arc-heater as a thermal driver for a 2-MWe MHD accelerator, which resides in a large-bore 2-tesla electromagnet. A preliminary design study using NaK seeded nitrogen as the working fluid led to an externally diagonalized segmented MHD channel configuration based on an expendable heat-sink design concept. The current status report includes a review of engineering/design work and performance optimization analyses and summarizes component hardware fabrication and development efforts, preliminary testing results, and recent progress toward full-up assembly and testing
Anomalous magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Giovannini, Massimo
2013-09-01
Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy of charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved coincide, in the perfectly conducting limit, with the ones obtainable in ideal magnetohydrodynamics where the anomalous currents are neglected. It is argued that this is the rationale for the ability to extend to anomalous magnetohydrodynamics the hydromagnetic solutions characterized by finite gyrotropy. The generally covariant aspects of the problem are addressed with particular attention to conformally flat geometries which are potentially relevant for the description of the electroweak plasma prior to the phase transition.
NASA Astrophysics Data System (ADS)
Haas, Fernando; Pascoal, Kellen Alves; Mendonça, José Tito
2016-01-01
A new neutrino magnetohydrodynamics (NMHD) model is formulated, where the effects of the charged weak current on the electron-ion magnetohydrodynamic fluid are taken into account. The model incorporates in a systematic way the role of the Fermi neutrino weak force in magnetized plasmas. A fast neutrino-driven short wavelengths instability associated with the magnetosonic wave is derived. Such an instability should play a central role in strongly magnetized plasma as occurs in supernovae, where dense neutrino beams also exist. In addition, in the case of nonlinear or high frequency waves, the neutrino coupling is shown to be responsible for breaking the frozen-in magnetic field lines condition even in infinite conductivity plasmas. Simplified and ideal NMHD assumptions were adopted and analyzed in detail.
Magneto-hydrodynamics simulation study of deflagration mode in co-axial plasma accelerators
NASA Astrophysics Data System (ADS)
Sitaraman, Hariswaran; Raja, Laxminarayan L.
2014-01-01
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.
Magneto-hydrodynamics simulation study of deflagration mode in co-axial plasma accelerators
Sitaraman, Hariswaran; Raja, Laxminarayan L.
2014-01-15
Experimental studies by Poehlmann et al. [Phys. Plasmas 17(12), 123508 (2010)] on a coaxial electrode magnetohydrodynamic (MHD) plasma accelerator have revealed two modes of operation. A deflagration or stationary mode is observed for lower power settings, while higher input power leads to a detonation or snowplow mode. A numerical modeling study of a coaxial plasma accelerator using the non-ideal MHD equations is presented. The effect of plasma conductivity on the axial distribution of radial current is studied and found to agree well with experiments. Lower conductivities lead to the formation of a high current density, stationary region close to the inlet/breech, which is a characteristic of the deflagration mode, while a propagating current sheet like feature is observed at higher conductivities, similar to the detonation mode. Results confirm that plasma resistivity, which determines magnetic field diffusion effects, is fundamentally responsible for the two modes.
Magnetohydrodynamic Augmented Propulsion Experiment: I. Performance Analysis and Design
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Cole, J. W.; Lineberry, J. T.; Chapman, J. N.; Schmidt, H. J.; Lineberry, C. W.
2003-01-01
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.
Nonlinear compressible magnetohydrodynamic flows modeling of a process ICP torch
NASA Astrophysics Data System (ADS)
Ikhlef, N.; Hacib, T.; Leroy, O.; Mkiddche, M. R.
2012-04-01
Magnetohydrodynamics (MHD) describes the physical behavior of inductively coupled plasma (ICP). The goal of this paper is to provide a physical understanding of a process ICP torch using a resistive MHD model. This includes a basic description and derivation of the fluid model. Inductive plasma is treated as a continuous, conducting fluid that satisfies the classical laws of motion and thermodynamics. This model combines fluid equations, similar to those used in fluid dynamics, with Maxwell's equations. Steady fluid flow and temperature equations are simultaneously solved (direct method) using a finite elements method (FEM). The electromagnetic field equations are formulated in terms of potential vector with applied voltage source, so this model is physically more consistent, a more accurate and a faster simulation. The governing resistive MHD equations for an inductive plasma flow under local thermodynamic equilibrium (LTE) and laminar flow are presented, with appropriate boundary conditions. The model enabled to obtain the electromagnetic fields, temperature and flow velocity distributions also allows the determination of the electric parameters such as impedance of the plasma torch, total power, eddy losses, etc.
Micromachined magnetohydrodynamic actuators and sensors
Lee, Abraham P.; Lemoff, Asuncion V.
2000-01-01
A magnetohydrodynamic (MHD) micropump and microsensor which utilizes micromachining to integrate the electrodes with microchannels and includes a magnet for producing magnetic fields perpendicular to both the electrical current direction and the fluid flow direction. The magnet can also be micromachined and integrated with the micropump using existing technology. The MHD micropump, for example, can generate continuous, reversible flow, with readily controllable flow rates. The flow can be reversed by either reversing the electrical current flow or reversing the magnetic field. By mismatching the electrodes, a swirling vortex flow can be generated for potential mixing applications. No moving parts are necessary and the dead volume is minimal. The micropumps can be placed at any position in a fluidic circuit and a combination of micropumps can generate fluidic plugs and valves.
Magnetohydrodynamics of chiral relativistic fluids
NASA Astrophysics Data System (ADS)
Boyarsky, Alexey; Frhlich, Jrg; Ruchayskiy, Oleg
2015-08-01
We study the dynamics of a plasma of charged relativistic fermions at very high temperature T ?m , where m is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magnetohydrodynamical description of the evolution of such a plasma. We show that, compared to conventional magnetohydronamics (MHD) for a plasma of nonrelativistic particles, the hydrodynamical description of the relativistic plasma involves new degrees of freedom described by a pseudoscalar 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 nonlinear 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.
Status of power generation experiments in the NASA Lewis closed cycle MHD facility
NASA Technical Reports Server (NTRS)
Sovie, R. J.; Nichols, L. D.
1971-01-01
The design and operation of the closed cycle MHD facility is discussed and results obtained in recent experiments are presented. The main components of the facility are a compressor, recuperative heat exchanger, heater, nozzle, MHD channel with 28 pairs of thoriated tungsten electrodes, cesium condenser, and an argon cooler. The facility has been operated at temperatures up to 2100 K with a cesium-seeded argon working fluid. At low magnetic field strengths, the open circuit voltage, Hall voltage and short circuit current obtained are 90, 69, and 47 percent of the theoretical equilibrium values, respectively. Comparison of this data with a wall and boundary layer leakage theory indicates that the generator has shorting paths in the Hall direction.
NASA Technical Reports Server (NTRS)
Staigner, P. J.; Abbott, J. M.
1980-01-01
Two parallel contracted studies were conducted. Each contractor investigated three base cases and parametric variations about these base cases. Each contractor concluded that two of the base cases (a plant using separate firing of an advanced high temperature regenerative air heater with fuel from an advanced coal gasifier and a plant using an intermediate temperature metallic recuperative heat exchanger to heat oxygen enriched combustion air) were comparable in both performance and cost of electricity. The contractors differed in the level of their cost estimates with the capital cost estimates for the MHD topping cycle and the magnet subsystem in particular accounting for a significant part of the difference. The impact of the study on the decision to pursue a course which leads to an oxygen enriched plant as the first commercial MHD plant is described.
Alfven Wave Tomography for Cold MHD Plasmas
I.Y. Dodin; N.J. Fisch
2001-09-07
Alfven waves propagation in slightly nonuniform cold plasmas is studied by means of ideal magnetohydrodynamics (MHD) nonlinear equations. The evolution of the MHD spectrum is shown to be governed by a matrix linear differential equation with constant coefficients determined by the spectrum of quasi-static plasma density perturbations. The Alfven waves are shown not to affect the plasma density inhomogeneities, as they scatter off of them. The application of the MHD spectrum evolution equation to the inverse scattering problem allows tomographic measurements of the plasma density profile by scanning the plasma volume with Alfven radiation.
Bloom, M. H.
1980-01-01
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)
Nonlinear subcritical magnetohydrodynamic beta limit
Waltz, R. E.
2010-07-15
Published gyrokinetic simulations have had difficulty operating beyond about half the ideal magnetohydrodynamic (MHD) critical beta limit with stationary and low transport levels in some well-established reference cases. Here it is demonstrated that this limitation is unlikely due to numerical instability, but rather appears to be a nonlinear subcritical MHD beta limit[R. E. Waltz, Phys. Rev. Lett. 55, 1098 (1985)] induced by the locally enhanced pressure gradients from the diamagnetic component of the nonlinearly driven (zero frequency) zonal flows. Strong evidence that the zonal flow corrugated pressure gradient profiles can act as a MHD-like beta limit unstable secondary equilibrium is provided. It is shown that the addition of sufficient ExB shear or operation closer to drift wave instability threshold, thereby reducing the high-n drift wave turbulence nonlinear pumping of the zonal flows, can allow the normal high-n ideal MHD beta limit to be reached with low transport levels. Example gyrokinetic simulations of experimental discharges are provided: one near the high-n beta limit reasonably matches the low transport levels needed when the high experimental level of ExB shear is applied; a second experimental example at moderately high beta appears to be limited by the subcritical beta.
Nonlinear subcritical magnetohydrodynamic beta limit
NASA Astrophysics Data System (ADS)
Waltz, R. E.
2010-07-01
Published gyrokinetic simulations have had difficulty operating beyond about half the ideal magnetohydrodynamic (MHD) critical beta limit with stationary and low transport levels in some well-established reference cases. Here it is demonstrated that this limitation is unlikely due to numerical instability, but rather appears to be a nonlinear subcritical MHD beta limit [R. E. Waltz, Phys. Rev. Lett. 55, 1098 (1985)] induced by the locally enhanced pressure gradients from the diamagnetic component of the nonlinearly driven (zero frequency) zonal flows. Strong evidence that the zonal flow corrugated pressure gradient profiles can act as a MHD-like beta limit unstable secondary equilibrium is provided. It is shown that the addition of sufficient E ×B shear or operation closer to drift wave instability threshold, thereby reducing the high-n drift wave turbulence nonlinear pumping of the zonal flows, can allow the normal high-n ideal MHD beta limit to be reached with low transport levels. Example gyrokinetic simulations of experimental discharges are provided: one near the high-n beta limit reasonably matches the low transport levels needed when the high experimental level of E ×B shear is applied; a second experimental example at moderately high beta appears to be limited by the subcritical beta.
NASA Astrophysics Data System (ADS)
Banerjee, D.; Krishna Prasad, S.
This chapter reviews the observations of magnetohydrodynamic (MHD) waves in coronal holes focusing primarily on progress made in the past few years. It also discusses on the new evidences of wave damping and highlights how such observations can be used to probe coronal conditions through seismology. Numerous observations, using imaging and spectroscopic techniques, have revealed the presence of different MHD waves in these structures that can be categorized into compressive and incompressive waves. One of the most desirable characteristics of MHD wave observations in the solar atmosphere, is their dissipation. The energy carried by these waves has to be deposited at appropriate heights to facilitate coronal heating and solar wind acceleration. It turned out that the compressive waves are easy to dissipate with the conventional physical mechanisms whereas the incompressive waves require some special conditions.
Smoothed Particle Hydrodynamics: Turbulence and MHD
NASA Astrophysics Data System (ADS)
Price, D. J.; Federrath, C.
2010-09-01
In this paper we discuss recent applications of the Smoothed Particle Hydrodynamics (SPH) method to the simulation of supersonic turbulence in the interstellar medium, as well as giving an update on recent algorithmic developments in solving the equations of magnetohydrodynamics (MHD) in SPH. Using high resolution calculations (up to 134 million particles), we find excellent agreement with grid-based results on a range of measures including the power spectrum slope in both the velocity field and the density-weighted velocity ?1/3 v, the latter showing a Kolmogorov-like k-5/3 scaling as proposed by Kritsuk et al. (2007). We also find good agreement on the statistics of the Probability Distribution Function (PDF) and structure functions, independently confirming the scaling found by Schmidt et al. (2008). On Smoothed Particle Magnetohydrodynamics (SPMHD) we have recently wasted a great deal of time and effort investigating the vector potential as an alternative to the Euler potentials formulation, in the end concluding that using the vector potential has even more severe problems than the standard (B-field based) SPMHD approach.
Robust and Efficient Riemann Solvers for MHD
NASA Astrophysics Data System (ADS)
Miyoshi, T.; Kusano, K.
2008-04-01
Robust and efficient approximate Riemann solvers for magnetohydrodynamics (MHD) are constructed. Particularly, a family of positively conservative Harten-Lax-van Leer (HLL)-type Riemann solvers, the so-called HLLD (`D' denotes Discontinuities), HLLR (`R' denotes Rotational), HLLC (`C' denotes Contact), and HLL solvers, is systematically considered.
Bloom, M.H.; Lederman, S.; Sforza, P.; Matalon, M.
1980-01-01
This is Part II of the Technical Progress Report on Tasks II-IV of the subject contract. It deals sequentially with Diagnostics and Instrumentation, the MHD Channel and the Combustor. During this period, a significant effort has gone into establishing a schematic design of a laser diagnostic system which can be applied to the flow-train of the MHD system, and to acquiring, assembling and shaking down a laboratory set-up upon which a prototype can be based. With further reference to the MHD Channel, a model analysis has been initiated of the two-dimensional MHD boundary layer between two electrodes in the limit of small magnetic Reynolds numbers with negligible effect of the flow on the applied magnetic field. An objective of this model study is the assessment of variations in initial conditions on the boundary layer behavior. Finally, the problem of combustion modeling has been studied on an initial basis. The open reports on this subject depict a high degree of empiricism, centering attention on global behavior mainly. A quasi-one-dimensional model code has been set-up to check some of the existing estimates. Also a code for equilibrium combustion has been activated.
A hybrid scheme for compressible magnetohydrodynamic turbulence
NASA Astrophysics Data System (ADS)
Yang, Yan; Wan, Minping; Shi, Yipeng; Yang, Kun; Chen, Shiyi
2016-02-01
An efficient, high-resolution and oscillation-free hybrid scheme for shock-turbulence interactions in compressible magnetohydrodynamic (MHD) problems is presented. The hybrid scheme couples a sixth-order compact finite difference scheme in the smooth regions with a fifth-order WENO scheme in the shock regions. An eighth-order pentadiagonal filter is derived and utilized to maintain numerical stability and eliminate spurious oscillations. Various numerical examples are presented and the hybrid algorithm is proved to be accurate for smooth solutions and be able to capture discontinuities robustly. We have also shown the good capability of the hybrid scheme for the compressible MHD turbulence.
Operation of a railgun accelerator for solid projectiles powered from an explosive MHD generator
Shvetsov, G.A.; Bashkatov, Y.L.; Orgov, A.V.; Stadnichenko, I.A.; Titov, V.M.
1984-11-01
These authors investigate the possibility of using an explosive MHD generator whose electrodes consist of the rails of a railgun accelerator so that the projectile is anitially accelerated by the action of electromagnetic forces and then, once the gas-cumulative jets reach the body, it can be subjected to additional acceleration by the gas flow moving at a high rate of speed. They conclude that the proposed compounded electrodynamic and gasdynamic acceleration scheme holds promise for achieving velocities in the 5-10 km/sec range.
Electromagnetic pulse and the electric power network
Klein, K.W.; Barnes, P.R.; Zaininger, H.W.
1984-01-01
This paper defines the nuclear electromagnetic pulse (EMP) - electric power system interaction problem. A description of high altitude EMP (HEMP) characteristics, source region EMP (SREMP) characteristics, and magnetohydrodynamics EMP (MHD-EMP) characteristics are presented. The results of initial calculations of EMP induced surges on electric power transmission and distribution lines are presented and compared with lightning induced surges. Potential EMP impacts on electric power systems are discussed, and an overview of the Department of Energy (DOE) EMP research program is presented.
NASA Astrophysics Data System (ADS)
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.
1980-02-01
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.
NASA Technical Reports Server (NTRS)
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
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.
MHD performance demonstration experiment, October 1, 1080-September 30, 1981
Whitehead, G. L.; Christenson, L. S.; Felderman, E. J.; Lowry, R. L.; Bordenet, E. J.
1981-12-01
The Arnold Engineering Development Center (AEDC) has been under contract with the Department of Energy (DOE) since December 1973 to conduct a magnetohydrodynamic (MHD) High Performance Demonstration Experiment (HPDE). The objective of this experimental research is to demonstrate the attainment of MHD performance on a sufficiently large scale to verify that projected commercial MHD objectives are possible. This report describes the testing of the system under power-producing conditions during the period from October 1, 1980 to September 30, 1981. Experimental results have been obtained with the channel configured in the Faraday mode. Test conditions were selected to produce low supersonic velocity along the entire channel length. Tests have been conducted at magnetic fields up to 4.1 Tesla (T) (70% of design). Up to 30.5 MW of power has been produced to date (60% of design) for an enthalpy extraction of approximately 11%. The high Hall voltage transient, observed during the previous series of tests has been reduced. The reduction is mostly probably due to the fuel and seed being introduced simultaneously. The replacement of the ATJ graphite caps on the electrode walls with pyrolytic graphite caps has resulted in significantly higher surface temperature. As a result, the voltage drop is some 60% of the cold wall voltage drop during the previous series of tests. However, the absolute value of the present voltage drop is still greater than the original design predictions. Test results indicate, however, that the overall enthalpy extraction objective can be achieved.
MHD direct channel from heat to electricity
NASA Astrophysics Data System (ADS)
Lihach, N.
1980-04-01
The potential benefits and difficulties of the development and operation of a combined MHD/steam electric generating plant are assessed. The concept of MHD power generation by the passage of extremely hot, pressurized coal combustion gases ionized by a seeding material through the field of a superconducting magnet, coupled with conventional steam generation using the MHD exhaust gases as a heat source, is outlined, and areas of MHD technology requiring extensive development are indicated. Recent research on these areas is reviewed, and achievements in MHD channel durability, superconducting magnets, power inverters and the planned start-up of a 40-50 MW component development and integration facility are noted. Development strategies to ensure the competitiveness of MHD with other advanced power systems are discussed, and means of ensuring reliability are indicated. The economic potential of MHD is considered, and it is noted that MHD may also be coupled with future fusion and high-temperature nuclear reactors.
Long-term evolution of decaying magnetohydrodynamic turbulence in the multiphase interstellar medium
Kim, Chang-Goo; Basu, Shantanu E-mail: basu@uwo.ca
2013-12-01
Supersonic turbulence in the interstellar medium (ISM) is believed to decay rapidly within a flow crossing time irrespective of the degree of magnetization. However, this general consensus of decaying magnetohydrodynamic (MHD) turbulence relies on local isothermal simulations, which are unable to take into account the roles of the global structures of magnetic fields and the ISM. Utilizing three-dimensional MHD simulations including interstellar cooling and heating, we investigate decaying MHD turbulence within cold neutral medium sheets embedded in a warm neutral medium. The early evolution of turbulent kinetic energy is consistent with previous results for decaying compressible MHD turbulence characterized by rapid energy decay with a power-law form of E∝t {sup –1} and by a short decay time compared with the flow crossing time. If initial magnetic fields are strong and perpendicular to the sheet, however, long-term evolution of the kinetic energy shows that a significant amount of turbulent energy (∼0.2E {sub 0}) still remains even after 10 flow crossing times for models with periodic boundary conditions. The decay rate is also greatly reduced as the field strength increases for such initial and boundary conditions, but not if the boundary conditions are those for a completely isolated sheet. We analyze velocity power spectra of the remaining turbulence to show that in-plane, incompressible motions parallel to the sheet dominate at later times.
Specific Mass Estimates for A Vapor Core Reactor With MHD
Knight, Travis; Smith, Blair; Anghaie, Samim
2002-07-01
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)
Solar-powered liquid-metal MHD performance and cost studies
Pierson, E.S.; Herman, H.
1981-01-01
The two-phase-generator, liquid-metal magnetohydrodynamic (LMMHD) energy-conversion concept was initially developed at Argonne National Laboratory to meet the anticipated need for an energy-conversion system compatible with liquid metal-cooled heat sources, such as the liquid-metal fast breeder reactor (LMFBR) and the controlled thermonuclear reactor (CTR). In particular, the use of two working fluids, a thermodynamic fluid (gas or vapor) and an electrodynamic fluid (liquid metal) to provide the electrical conductivity, gives LMMHD great versatility in coupling to differing heat-source temperatures and meeting material constraints, e.g., heat addition can be to the liquid metal, the gas or vapor, or both. Three LMMHD versions are under investigation.
Toward Estimating Current Densities in Magnetohydrodynamic Generators
NASA Astrophysics Data System (ADS)
Bokil, V. A.; Gibson, N. L.; McGregor, D. A.; Woodside, C. R.
2015-09-01
We investigate the idea of reconstructing current densities in a magnetohydrodynamic (MHD) generator channel from external magnetic flux density measurements in order to determine the existence and location of damaging arcs. We model the induced fields, which are usually neglected in low magnetic Reynold's number flows, using a natural fixed point iteration. Further we present a sensitivity analysis of induced fields to current density profiles in a 3D, yet simplified model.
Collisionless Magnetohydrodynamic Turbulence in Two Dimensions
NASA Astrophysics Data System (ADS)
Shivamoggi, Bhimsen
2006-11-01
Collisionless magnetohydrodynamic (MHD) turbulence in two dimensions is discussed [1]. Effects of electron inertia and electron pressure are included. Vortex formation at scales of the order of ion gyro-radius is predicted and compared with recent in situ European multi-satellite observations [2]. References: [1] B.K.Shivamoggi : Ann. Phys. 315,1, (2005). [2] D.Sundkvist et al.: Nature 436, 825, (2005).
Exact solutions of the incompressible dissipative Hall magnetohydrodynamics
Xia, Zhenwei; Yang, Weihong
2015-03-15
By using analytical method, the exact solutions of the incompressible dissipative Hall magnetohydrodynamics (MHD) equations are derived. It is found that a phase difference may occur between the velocity and magnetic field fluctuations when the kinetic and magnetic Reynolds numbers are both very large. Since velocity and magnetic field fluctuations are both circular polarized, the phase difference makes them no longer parallel or anti-parallel like that in the incompressible ideal Hall MHD.
A Leaky Waveguide Model for MHD Wave Driven Winds from Coronal Holes
NASA Technical Reports Server (NTRS)
Davila, J. M.
1985-01-01
Magnetohydrodynamic (MHD) waves, driven by the large scale convective motions of the photosphere are suggested as a possible source of additional acceleration for the stellar wind. Most of the turbulent power in a coronal hole is carried by MHD waves with periods of a few hundred seconds or longer. This is evident from direct observations of turbulence in the solar photosphere, as well as in situ observations of turbulence in the solar wind. But waves with periods this long have wavelengths which are typically as large as the transverse scale of the coronal hole flux tube itself. For these waves boundary effects are important and the coronal hole must be treated as a waveguide. The propagation of MHD waves using this waveguide approach is discussed. The simple model presented demonstrates that coronal holes can act as waveguides for MHD waves. For typical solar parameters the waves are compressible and can generate a wave tensile force which tends to cancel at least part of the wave pressure force. This effect tends to decrease the efficiency of MHD wave acceleration.
Modeling extreme (Carrington-type) space weather events using three-dimensional MHD code simulations
NASA Astrophysics Data System (ADS)
Ngwira, C. M.; Pulkkinen, A. A.; Kuznetsova, M. M.; Glocer, A.
2013-12-01
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.
MHD and Kinetic Modeling of the Ionospheres of Venus and Mars
Shinagawa, H.; Terada, N.
2009-06-16
It is widely recognized that both Venus and Mars possess no significant global intrinsic magnetic fields, and that the solar wind interacts directly with the upper atmospheres and ionospheres of Venus and Mars. In addition, local crustal magnetic fields are also present in various regions at Mars, suggesting that some regions of the Martian ionosphere are influenced not only by the solar wind but also by the crustal magnetic field. Previous studies have suggested that the basic structures of the ionospheres of the planets can be described by fluid and MHD(magnetohydrodynamic) processes. Various models of the ionospheres of Venus and Mars based on the MHD formulation have been constructed during the last two decades. Although the MHD approach has been successful in reproducing the ionospheres of the planets, some studies have indicated that MHD modeling is not necessarily appropriate in the regions of the topside ionosphere, the ionopause, and the magnetosheath, where the ion kinetic processes are likely to play an important role. The kinetic processes in the topside ionosphere might have significant influences even in the lower ionosphere. Thanks to a great progress made for computer power as well as the efficiency of calculations of the hybrid model, high-resolution kinetic models of the solar wind interaction with Venus and Mars, which self-consistently include the ionosphere, have been developed. In this paper, status of MHD and kinetic modeling of the ionospheres of Venus and Mars is briefly reviewed.
NASA Technical Reports Server (NTRS)
Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.
1975-01-01
Terminal voltage measurements with various cathodes and anodes in a high power, quasi-steady magnetoplasmadynamic (MPD) are discussed. The magnitude of the current at the onset of voltage fluctuations is shown to be an increasing function of cathode area and a weaker decreasing function of anode area. Tests with a fluted cathode indicated that the fluctuations originate in the plasma adjacent to the cathode rather than at the cathode surface. Measurements of radiative output from an optical cavity aligned to examine the current-carrying portion of a two-dimensional, 56 kA magnetoplasmadynamic discharge reveal no lasing in that region, consistent with calculations of electron excitation and resonance radiation trapping. A voltage-swept double probe technique allows single-shot determination of electron temperature and electron number density in the recombining MPD exhaust flow. Current distributions within the cavity of MPD hollow cathodes for various static prefills with no injected mass flow are examined.
Converging cylindrical shocks in ideal magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.
2014-09-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{μ _0/p_0} I/(2 π ) where I is the current, μ0 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.
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.
2014-09-15
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{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.
NASA Astrophysics Data System (ADS)
Sovie, R. J.; Winter, J. M.; Juhasz, A. J.; Berg, R. D.
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.
NASA Technical Reports Server (NTRS)
Sovie, R. J.; Winter, J. M.; Juhasz, A. J.; Berg, R. D.
1982-01-01
A conceptual design study of the MHD/steam plant that incorporates the use of oxygen enriched air preheated in a metallic heat exchanger as the combustor oxidant showed that this plant is the most attractive for early commercial applications. The variation of performance and cost was investigated as a function of plant size. The contractors' results for the overall efficiencies are in reasonable agreement considering the slight differences in their plant designs. NASA LeRC is reviewing cost and performance results for consistency with those of previous studies, including studies of conventional steam plants. LeRC in house efforts show that there are still many tradeoffs to be considered for these oxygen enriched plants and considerable variations can be made in channel length and level of oxygen enrichment with little change in overall plant efficiency.
NASA Astrophysics Data System (ADS)
Murphree, D. L.; Cook, R. L.; Bauman, L. E.; Benton, R. D.; Probert, P. B.; Selby, R. C.
1981-01-01
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.
Self-organized criticality in MHD driven plasma edge turbulence
NASA Astrophysics Data System (ADS)
dos Santos Lima, G. Z.; Iarosz, K. C.; Batista, A. M.; Caldas, I. L.; Guimarães-Filho, Z. O.; Viana, R. L.; Lopes, S. R.; Nascimento, I. C.; Kuznetsov, Yu. K.
2012-01-01
We analyze long-range time correlations and self-similar characteristics of the electrostatic turbulence at the plasma edge and scrape-off layer in the Tokamak Chauffage Alfvén Brésillien (TCABR), with low and high Magnetohydrodynamics (MHD) activity. We find evidence of self-organized criticality (SOC), mainly in the region near the tokamak limiter. Comparative analyses of data before and during the MHD activity reveals that during the high MHD activity the Hurst parameter decreases. Finally, we present a cellular automaton whose parameters are adjusted to simulate the analyzed turbulence SOC change with the MHD activity variation.
Not Available
1992-11-01
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).
System study of an MHD/gas turbine combined-cycle baseload power plant. HTGL report No. 134
Annen, K.D.
1981-08-01
The MHD/gas turbine combined-cycle system has been designed specifically for applications where the availability of cooling water is very limited. The base case systems which were studied consisted of an MHD plant with a gas turbine bottoming plant, and required no cooling water. The gas turbine plant uses only air as its working fluid and receives its energy input from 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.
Phase transition-like behavior of magnetospheric substorms: Global MHD simulation results
NASA Astrophysics Data System (ADS)
Shao, X.; Sitnov, M. I.; Sharma, S. A.; Papadopoulos, K.; Goodrich, C. C.; Guzdar, P. N.; Milikh, G. M.; Wiltberger, M. J.; Lyon, J. G.
2003-01-01
Using nonlinear dynamical techniques, we statistically investigate whether the simulated substorms from global magnetohydrodynamic (MHD) models have a combination of global and multiscale features, revealed in substorm dynamics by [2000] and featured the phase transition-like behavior. We simulate seven intervals of total duration of 280 hours from the data set used in the above works [, 1985]. We analyze the input-output (vBs-pseudo AL index) system obtained from the global MHD model and compare the results to those inferred from the original set (vBs-observed AL index). The analysis of the coupled vBs-pseudo AL index system shows the first-order phase transition map, which is consistent with the map obtained for the vBs-observed AL index system. Although the comparison between observations and global MHD simulations for individual events may vary, the overall global transition pattern during the substorm cycle revealed by singular spectrum analysis (SSA) is statistically consistent between simulations and observations. The coupled vBs-pseudo AL index system also shows multiscale behavior (scale-invariant power law dependence) in SSA power spectrum. Besides, we find the critical exponent of the nonequilibrium transitions in the magnetosphere, which reflects the multiscale aspect of the substorm activity, different from power law frequency of autonomous systems. The exponent relates input and output parameters of the magnetosphere. We also discuss the limitations of the global MHD model in reproducing the multiscale behavior when compared to the real system.
Multimegawatt nuclear electric propulsion with gaseous and vapor core reactors with MHD
NASA Astrophysics Data System (ADS)
Knight, Travis; Anghaie, Samim; Smith, Blair; Houts, Michael
2001-02-01
This study investigated the development of a system concept for space power generation and nuclear electric propulsion based on a fissioning plasma core reactor (FPCR) with magnetohydrodynamic (MHD) power conversion system, coupled to a magnetoplasmadynamic (MPD) thruster. The FPCR is a liquid-vapor core reactor concept operating with metallic uranium or uranium tetrafluoride (UF4) vapor as the fissioning fuel and alkali metals or their fluorides as working fluid in a closed Rankine cycle with MHD energy conversion. Candidate working fluids include K, Li, Na, KF, LiF, NaF, etc. The system features core outlet temperatures of 3000 to 4000 K at pressures of about 1 to 10 MPa, MHD temperatures of 2000 to 3000 K, and radiator temperatures of 1200 to 2000 K. This combination of parameters offers the potential for low total system specific mass in the range of 0.4 to 0.6 kg/kWe. The MHD output could be coupled with minimal power conditioning to the variable specific impulse magnetoplasma rocket (VASIMR), MPD thrusters or other types of thruster for producing thrust at very high specific impulse (Isp=1500 to 10,000 s). .
NASA Astrophysics Data System (ADS)
Murakami, Tomoyuki; Zhuang, Yunqin; Okuno, Yoshihiro
2013-02-01
We describe high-density magnetohydrodynamic (MHD) energy conversion in a high-temperature seed-free argon plasma, for which a compact linear-shaped Faraday-type MHD electrical power generator is used. Short-time-duration single-pulse shock-tunnel-based experiments demonstrate the MHD energy conversion with varying total inflow temperature up to 9000 K and applied magnetic-flux density up to 4.0 T. The high-temperature plasma is transformed from the thermal-equilibrium state at the entrance to the weak-nonequilibrium state in the supersonic MHD channel. The discharge structure is reasonably homogeneous without suffering from serious streamer development. The power generation performance is monotonically improved by increasing total inflow temperature and strength of magnetic field. The enthalpy extraction efficiency of 13.1% and overall power density of 0.16 GW/m3 are attained. The local power density at the middle of the channel reaches 0.24 GW/m3.
Possible signatures of nonlinear MHD waves in the solar wind: UVCS observations and models
NASA Technical Reports Server (NTRS)
Ofman, L.; Romoli, M.; Davila, J. M.; Poletto, G.; Kohl, J.; Noci, G.
1997-01-01
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.
Global magnetohydrodynamic simulations on multiple GPUs
NASA Astrophysics Data System (ADS)
Wong, Un-Hong; Wong, Hon-Cheng; Ma, Yonghui
2014-01-01
Global magnetohydrodynamic (MHD) models play the major role in investigating the solar wind-magnetosphere interaction. However, the huge computation requirement in global MHD simulations is also the main problem that needs to be solved. With the recent development of modern graphics processing units (GPUs) and the Compute Unified Device Architecture (CUDA), it is possible to perform global MHD simulations in a more efficient manner. In this paper, we present a global magnetohydrodynamic (MHD) simulator on multiple GPUs using CUDA 4.0 with GPUDirect 2.0. Our implementation is based on the modified leapfrog scheme, which is a combination of the leapfrog scheme and the two-step Lax-Wendroff scheme. GPUDirect 2.0 is used in our implementation to drive multiple GPUs. All data transferring and kernel processing are managed with CUDA 4.0 API instead of using MPI or OpenMP. Performance measurements are made on a multi-GPU system with eight NVIDIA Tesla M2050 (Fermi architecture) graphics cards. These measurements show that our multi-GPU implementation achieves a peak performance of 97.36 GFLOPS in double precision.
A Comparison of Two Intermediate State HLLC Solvers for Ideal Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Gurski, K. F.
2008-04-01
This paper compares a solver based on the HLLC (Harten-Lax-van Leer-contact wave) approximate nonlinear Riemann solver for gas dynamics for ideal magnetohydrodynamics (MHD) with the HLL, Roe, Linde, and Li solvers. Simulation results are given for three one-dimensional test cases not previously shown in the original paper presenting the smooth HLLC solver for MHD.
Transport in two-fluid magnetohydrodynamic turbulence.
Kim, Eun-jin
2007-08-01
We present a theory of transport of magnetic flux and momentum in two fluid three-dimensional reduced magnetohydrodynamic (MHD) turbulence. By including the effects of shear flows and magnetic fields consistently, we show that kinetic Alfven waves can help weaken the quenching in turbulent transport of a strong magnetic field B0 found in single fluid MHD turbulence, leading to turbulent magnetic diffusivity eta(T) proportional (eta/Omega)(1/3)B(0)(-2). Here, eta and Omega are the Ohmic diffusivity and the shearing rate of the shear flow. Momentum transport is diffusive, with the value of eddy viscosity larger than that in single fluid MHD turbulence. The effects of drift waves are found to be weaker. Implications for the instability of shear flows are discussed. PMID:17930096
Action principles for extended magnetohydrodynamic models
Keramidas Charidakos, I.; Lingam, M.; Morrison, P. J.; White, R. L.; Wurm, A.
2014-09-15
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.
Nuclear magnetohydrodynamic EMP, solar storms, and substorms
Rabinowitz, M. ); Meliopoulous, A.P.S.; Glytsis, E.N. . School of Electrical Engineering); Cokkinides, G.J. )
1992-10-20
In addition to a fast electromagnetic pulse (EMP), a high altitude nuclear burst produces a relatively slow magnetohydrodynamic EMP (MHD EMP), whose effects are like those from solar storm geomagnetically induced currents (SS-GIC). The MHD EMP electric field E [approx lt] 10[sup [minus] 1] V/m and lasts [approx lt] 10[sup 2] sec, whereas for solar storms E [approx gt] 10[sup [minus] 2] V/m and lasts [approx gt] 10[sup 3] sec. Although the solar storm electric field is lower than MHD EMP, the solar storm effects are generally greater due to their much longer duration. Substorms produce much smaller effects than SS-GIC, but occur much more frequently. This paper describes the physics of such geomagnetic disturbances and analyzes their effects.
NASA Astrophysics Data System (ADS)
Passos, D. M. D. C.; Charbonneau, P.
2014-12-01
The steady advance in computer power has finally enabled us to explore the solar dynamo problem by means of 3D global magnetohydrodynamical (MHD) simulations of the convection zone.Using the EULAG-MHD code, we have succeeded in producing simulations of the Sun's magnetic activity cycles that resemble the observed evolutionary patterns of the large-scale solar magnetic field. In these simulations the anelastic ideal MHD equations are solved in a thick, rotating shell of electrically conducting fluid, under solar-like stratification and thermal forcing. Since these simulations are fully dynamical in all time and spatial resolved scales, they achieve highly turbulent regimes and naturally produce variable amplitude solutions.We have recently been able to produce a simulation that spans for 1650 years and that produced 40 complete sunspot like cycles, the longest of its kind so far.This allows to perform statistical studies and establish direct comparisons with the observed solar cycle. Some of the main similarities and differences between the statistical properties of simulated and observed cycles are presented here (e.g. evidence for Gnevyshev-Ohl patterns, Gleissberg modulation or hemispheric coupling). Additionally, by studying the behaviour of the large scale flows in the simulation (differential rotation and meridional circulation) we also find evidence for solar cycle modulation of the deep equatorward flow in the meridional circulation. This result is briefly discussed as well as its implications for current helioseismic measurement methodologies and for classical kinematic mean-field flux transport dynamo simulations.
Not Available
1995-02-01
The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU), under U.S. Department of Energy (DOE) Contract No. DE-AC02-80ET-15601, Diagnostic Development and Support of MHD Test Facilities, developed 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, were refined, and new systems to measure temperatures and gas-seed-slag stream characteristics were developed. To further data acquisition and analysis capabilities, the diagnostic systems were interfaced with DIAL`s computers. Technical support was provided for the diagnostic needs of the national MHD research effort. DIAL personnel also cooperated with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs. The initial contract, Testing and Evaluation of Heat Recovery/Seed Recovery, established a data base on heat transfer, slagging effects on heat transfer surfaces, metal durability, secondary combustor performance, secondary combustor design requirements, and other information pertinent to the design of HR/SR components at the Coal-Fired Flow Facility (CFFF). To accomplish these objectives, a combustion test stand was constructed that simulated MHD environments, and mathematical models were developed and evaluated for the heat transfer in hot-wall test sections. Two transitions occurred during the span of this contract. In May 1983, the objectives and title of the contract changed from Testing and Evaluation of Heat Recovery/Seed Recovery to Diagnostic Development and Support of MHD Test Facilities. In July 1988, the research laboratory`s name changed from the MHD Energy Center to the Diagnostic Instrumentation and Analysis Laboratory.
MHD coal-fired flow facility. Annual technical progress report, October 1979-September 1980
Alstatt, M.C.; Attig, R.C.; Brosnan, D.A.
1981-03-01
The University of Tennessee Space Institute (UTSI) reports on significant activity, task status, planned research, testing, development, and conclusions for the Magnetohydrodynamics (MHD) Coal-Fired Flow Faclity (CFFF) and the Energy Conversion Facility (ECF).
Computation of multi-region relaxed magnetohydrodynamic equilibria
NASA Astrophysics Data System (ADS)
Hudson, S. R.; Dewar, R. L.; Dennis, G.; Hole, M. J.; McGann, M.; von Nessi, G.; Lazerson, S.
2012-11-01
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.
Computation of Multi-region Relaxed Magnetohydrodynamic Equilibria
Hudson, S. R.; Dewar, R. L.; Dennis, G.; Hole, M. J.; McGann, M.; von Nessi, G.; Lazerson, S.
2013-03-29
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.
Computation of multi-region relaxed magnetohydrodynamic equilibria
Hudson, S. R.; Lazerson, S.; Dewar, R. L.; Dennis, G.; Hole, M. J.; McGann, M.; Nessi, G. von
2012-11-15
We describe the construction of stepped-pressure equilibria as extrema of a multi-region, relaxed magnetohydrodynamic (MHD) energy functional that combines elements of ideal MHD and Taylor relaxation, and which we call MRXMHD. The model is compatible with Hamiltonian chaos theory and allows the three-dimensional MHD equilibrium problem to be formulated in a well-posed manner suitable for computation. The energy-functional is discretized using a mixed finite-element, Fourier representation for the magnetic vector potential and the equilibrium geometry; and numerical solutions are constructed using the stepped-pressure equilibrium code, SPEC. Convergence studies with respect to radial and Fourier resolution are presented.
Benchmark solutions for MHD solver development
NASA Astrophysics Data System (ADS)
Tao, Zhen; Ni, MingJiu
2013-02-01
A benchmark solution is of great importance in validating algorithms and codes for magnetohydrodynamic (MHD) flows. Hunt and Shercliff's solutions are usually employed as benchmarks for MHD flows in a duct with insulated walls or with thin conductive walls, in which wall effects on MHD are represented by the wall conductance ratio. With wall thickness resolved, it is stressed that the solution of Sloan and Smith's and the solution of Butler's can be used to check the error of the thin wall approximation condition used for Hunt's solutions. It is noted that Tao and Ni's solutions can be used as a benchmark for MHD flows in a duct with wall symmetrical or unsymmetrical, thick or thin. When the walls are symmetrical, Tao and Ni's solutions are reduced to Sloan and Smith's solution and Butler's solution, respectively.
High-order gas-kinetic methods for ideal magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Tang, Huazhong
1999-06-01
This article is to study extension of gas-kinetic theory based flux splitting methods to ideal magnetohydrodynamics (MHD) equations. Uniform high-order gas kinetic methods are presented, based on TVD type Runge-Kutta time discretization and technique of the initial reconstruction. The numerical results have been given to show robustness of our schemes.
Solar Wind Turbulence from MHD to Sub-ion Scales: High-resolution Hybrid Simulations
NASA Astrophysics Data System (ADS)
Franci, Luca; Verdini, Andrea; Matteini, Lorenzo; Landi, Simone; Hellinger, Petr
2015-05-01
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 wavenumbers. The simulation results simultaneously exhibit several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magnetohydrodynamic (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 Ohms law.
Gas Core Reactor Numerical Simulation Using a Coupled MHD-MCNP Model
NASA Technical Reports Server (NTRS)
Kazeminezhad, F.; Anghaie, S.
2008-01-01
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.
Accurate, meshless methods for magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Hopkins, Philip F.; Raives, Matthias J.
2016-01-01
Recently, we explored new meshless finite-volume Lagrangian methods for hydrodynamics: the `meshless finite mass' (MFM) and `meshless finite volume' (MFV) methods; these capture advantages of both smoothed particle hydrodynamics (SPH) and adaptive mesh refinement (AMR) schemes. We extend these to include ideal magnetohydrodynamics (MHD). The MHD equations are second-order consistent and conservative. We augment these with a divergence-cleaning scheme, which maintains nabla \\cdot B≈ 0. We implement these in the code GIZMO, together with state-of-the-art SPH MHD. We consider a large test suite, and show that on all problems the new methods are competitive with AMR using constrained transport (CT) to ensure nabla \\cdot B=0. They correctly capture the growth/structure of the magnetorotational instability, MHD turbulence, and launching of magnetic jets, in some cases converging more rapidly than state-of-the-art AMR. Compared to SPH, the MFM/MFV methods exhibit convergence at fixed neighbour number, sharp shock-capturing, and dramatically reduced noise, divergence errors, and diffusion. Still, `modern' SPH can handle most test problems, at the cost of larger kernels and `by hand' adjustment of artificial diffusion. Compared to non-moving meshes, the new methods exhibit enhanced `grid noise' but reduced advection errors and diffusion, easily include self-gravity, and feature velocity-independent errors and superior angular momentum conservation. They converge more slowly on some problems (smooth, slow-moving flows), but more rapidly on others (involving advection/rotation). In all cases, we show divergence control beyond the Powell 8-wave approach is necessary, or all methods can converge to unphysical answers even at high resolution.
An MHD variational principle that admits reconnection
NASA Technical Reports Server (NTRS)
Rilee, M. L.; Sudan, R. N.; Pfirsch, D.
1997-01-01
The variational approach of Pfirsch and Sudan's averaged magnetohydrodynamics (MHD) to the stability of a line-tied current layer is summarized. The effect of line-tying on current sheets that might arise in line-tied magnetic flux tubes by estimating the growth rates of a resistive instability using a variational method. The results show that this method provides a potentially new technique to gauge the stability of nearly ideal magnetohydrodynamic systems. The primary implication for the stability of solar coronal structures is that tearing modes are probably constant at work removing magnetic shear from the solar corona.
Broken Ergodicity in MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2010-01-01
Ideal magnetohydrodynamic (MHD) turbulence may be represented by finite Fourier series, where the inherent periodic box serves as a surrogate for a bounded astrophysical plasma. Independent Fourier coefficients form a canonical ensemble described by a Gaussian probability density function containing a Hermitian covariance matrix with positive eigenvalues. The eigenvalues at lowest wave number can be very small, resulting in a large-scale coherent structure: a turbulent dynamo. This is seen in computations and a theoretical explanation in terms of 'broken ergodicity' contains Taylor s theory of force-free states. An important problem for future work is the case of real, i.e., dissipative flows. In real flows, broken ergodicity and coherent structure are still expected to occur in MHD turbulence at the largest scale, as suggested by low resolution simulations. One challenge is to incorporate coherent structure at the largest scale into the theory of turbulent fluctuations at smaller scales.
NASA Astrophysics Data System (ADS)
Retallick, F. D.
1980-10-01
Directly-fired, separately-fired, and oxygen-augmented MHD power plants incorporating a disk geometry for the MHD generator were studied. The base parameters defined for four near-optimum-performance MHD steam power systems of various types are presented. The finally selected systems consisted of (1) two directly fired cases, one at 1920 K (2996F) preheat and the other at 1650 K (2500 F) preheat, (2) a separately-fired case where the air is preheated to the same level as the higher temperature directly-fired cases, and (3) an oxygen augmented case with the same generator inlet temperature of 2839 (4650F) as the high temperature directly-fired and separately-fired cases. Supersonic Mach numbers at the generator inlet, gas inlet swirl, and constant Hall field operation were specified based on disk generator optimization. System pressures were based on optimization of MHD net power. Supercritical reheat stream plants were used in all cases. Open and closed cycle component costs are summarized and compared.
NASA Technical Reports Server (NTRS)
Retallick, F. D.
1980-01-01
Directly-fired, separately-fired, and oxygen-augmented MHD power plants incorporating a disk geometry for the MHD generator were studied. The base parameters defined for four near-optimum-performance MHD steam power systems of various types are presented. The finally selected systems consisted of (1) two directly fired cases, one at 1920 K (2996F) preheat and the other at 1650 K (2500 F) preheat, (2) a separately-fired case where the air is preheated to the same level as the higher temperature directly-fired cases, and (3) an oxygen augmented case with the same generator inlet temperature of 2839 (4650F) as the high temperature directly-fired and separately-fired cases. Supersonic Mach numbers at the generator inlet, gas inlet swirl, and constant Hall field operation were specified based on disk generator optimization. System pressures were based on optimization of MHD net power. Supercritical reheat stream plants were used in all cases. Open and closed cycle component costs are summarized and compared.
Structure Formation through Magnetohydrodynamical Instabilities in Protoplanetary Disks
NASA Astrophysics Data System (ADS)
Noguchi, K.; Tajima, T.; Horton, W.
2000-12-01
The shear flow instabilities under the presence of magnetic fields in the protoplanetary disk can greatly facilitate the formation of density structures that serve as seeds prior to the onset of the gravitational Jeans instability. Such a seeding process may explain several outstanding puzzles in the planetary genesis that are further compounded by the new discoveries of extrasolar planets and a new insight into the equation of state of dense matter. This puzzle also includes the apparent narrow window of the age difference of the Sun and the Earth. We evaluate the effects of the Parker, magnetorotational(Balbus-Hawley), and kinematic dynamo instabilities by comparing the properties of these instabilities. We calculate the mass spectra of aggregated density structures by the above mechanism in the radial direction for an axisymmetric magnetohydrodynamic(MHD) torus equiblium and power-law density profile models. The mass spectrum of the magnetorotational instability may describe the origin of giant planets away from the central star such as Jupiter. Our local three-dimentional MHD simulation indicates that the coupling of the Parker and magnetorotational instabilities creates spiral arms and gas blobs in the accretion disk, reinforcing the theory and model.
Supersonic regime of the Hall-magnetohydrodynamics resistive tearing instability
Ahedo, Eduardo; Ramos, Jesus J.
2012-07-15
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.
Variational formulation of relaxed and multi-region relaxed magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Dewar, R. L.; Yoshida, Z.; Bhattacharjee, A.; Hudson, S. R.
2015-12-01
> Ideal magnetohydrodynamics (IMHD) is strongly constrained by an infinite number of microscopic constraints expressing mass, entropy and magnetic flux conservation in each infinitesimal fluid element, the latter preventing magnetic reconnection. By contrast, in the Taylor relaxation model for formation of macroscopically self-organized plasma equilibrium states, all these constraints are relaxed save for the global magnetic fluxes and helicity. A Lagrangian variational principle is presented that leads to a new, fully dynamical, relaxed magnetohydrodynamics (RxMHD), such that all static solutions are Taylor states but also allows state with flow. By postulating that some long-lived macroscopic current sheets can act as barriers to relaxation, separating the plasma into multiple relaxation regions, a further generalization, multi-region relaxed magnetohydrodynamics (MRxMHD) is developed.
A Three-Fluid, Implicit, MHD Code
NASA Astrophysics Data System (ADS)
Lileikis, D. E.
1996-11-01
A three fluid, implicit, magnetohydrodynamics (MHD) code has been developed for the study of plasma rocket thrusters. The code solves the coupled MHD equations for a two dimensional, planar geometry using a modified form of the Beam & Warming alternating direction implicit scheme. Hall effect, ion slip and electron pressure gradient terms are retained in Ohm's law. Interaction between the electrons, ions and neutrals is handled via approximations to the elastic collision integrals. Nonequilibrium electron-impact ionization and three- body recombination models are also included in the model.
Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH). Part 1
NASA Technical Reports Server (NTRS)
Micheletti, David A.; Baughman, Jack A.; Nelson, Gordon L.; Simmons, Gloyd A.
1997-01-01
This report documents the activities, results, conclusions and recommendations of the Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH) Project in which the use of magnetohydrodynamics (MHD) technology is investigated for its applicability to augment hypersonic wind tunnels. The long range objective of this investigation is to advance the development of ground test facilities to support the development of hypervelocity flight vehicles. The MHD accelerator adds kinetic energy directly to the wind tunnel working fluid, thereby increasing its Mach number to hypervelocity levels. Several techniques for MHD augmentation, as well as other physical characteristics of the process are studied to enhance the overall performance of hypersonic wind tunnel design. Specific recommendations are presented to improve the effectiveness of ground test facilities. The work contained herein builds on nearly four decades of research and experimentation by the aeronautics ground test and evaluation community, both foreign and domestic.
Magnetohydrodynamics Accelerator Research into Advanced Hypersonics (MARIAH). Part 2
NASA Technical Reports Server (NTRS)
Baughman, Jack A.; Micheletti, David A.; Nelson, Gordon L.; Simmons, Gloyd A.
1997-01-01
This report documents the activities, results, conclusions and recommendations of the Magnetohydrodynamics Accelerator Research Into Advanced Hypersonics (MARIAH) Project in which the use of magnetohydrodynamics (MHD) technology is investigated for its applicability to augment hypersonic wind tunnels. The long range objective of this investigation is to advance the development of ground test facilities to support the development of hypervelocity flight vehicles. The MHD accelerator adds kinetic energy directly to the wind tunnel working fluid, thereby increasing its Mach number to hypervelocity levels. Several techniques for MHD augmentation, as well as other physical characteristics of the process are studied to enhance the overall performance of hypersonic wind tunnel design. Specific recommendations are presented to improve the effectiveness of ground test facilities. The work contained herein builds on nearly four decades of research and experimentation by the aeronautics ground test and evaluation community, both foreign and domestic.
Method for manufacturing magnetohydrodynamic electrodes
Killpatrick, Don H. (Orland Park, IL); Thresh, Henry R. (Palos Heights, IL)
1982-01-01
A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator comprising the steps of preparing a billet having a core 10 of a first metal, a tubular sleeve 12 of a second metal, and an outer sheath 14, 16, 18 of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket 14. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MDH channel frame. The method forms a bond between the first metal of the core 10 and the second metal of the sleeve 12 strong enough to withstand a hot and corrosive environment.
Low-frequency circuit analysis of MHD-EMP-induced transients on three-phase distribution systems
Mayhall, D.J.; Yee, J.H.
1992-07-01
The magnetohydrodynamic electromagnetic pulse (MHD-EMP) generated by a nuclear explosion in the earth`s ionosphere is believed by a number of researchers to pose a potentially severe threat to long electric utility transmission and distribution systems in the United States. The disturbances caused by MHD-EMP are similar to the electromagnetic transients caused by solar-induced geomagnetic storms, but are generally expected to be more intense with shorter durations. Recent solar-induced storms have caused appreciable damage to electric utility equipment in Canada and the northern United States. In March of 1989, a solar-induced geomagnetic storm caused a blackout of the Hydro-Quebec power system in the province of Quebec, failure of step-up power transformers at the Salem Nuclear Generating Plant of the Public Service Electric and Gas Company, and a number of less severe power disruptions in the United States. Since the amplitudes of MHD-EMP induced transients are expected to be stronger than those produced by solar-induced geomagnetic storms, unprotected electric utility power systems may be quite vulnerable to MHD-EMP.
Low-frequency circuit analysis of MHD-EMP-induced transients on three-phase distribution systems
Mayhall, D.J.; Yee, J.H.
1992-07-01
The magnetohydrodynamic electromagnetic pulse (MHD-EMP) generated by a nuclear explosion in the earth's ionosphere is believed by a number of researchers to pose a potentially severe threat to long electric utility transmission and distribution systems in the United States. The disturbances caused by MHD-EMP are similar to the electromagnetic transients caused by solar-induced geomagnetic storms, but are generally expected to be more intense with shorter durations. Recent solar-induced storms have caused appreciable damage to electric utility equipment in Canada and the northern United States. In March of 1989, a solar-induced geomagnetic storm caused a blackout of the Hydro-Quebec power system in the province of Quebec, failure of step-up power transformers at the Salem Nuclear Generating Plant of the Public Service Electric and Gas Company, and a number of less severe power disruptions in the United States. Since the amplitudes of MHD-EMP induced transients are expected to be stronger than those produced by solar-induced geomagnetic storms, unprotected electric utility power systems may be quite vulnerable to MHD-EMP.
Perfect magnetohydrodynamics as a field theory
Bekenstein, Jacob D.; Betschart, Gerold
2006-10-15
We propose the generally covariant action for the theory of a self-coupled complex scalar field and electromagnetism which by virtue of constraints is equivalent, in the regime of long wavelengths, to perfect magnetohydrodynamics (MHD). We recover from it the Euler equation with Lorentz force, and the thermodynamic relations for a prefect fluid. The equation of state of the latter is related to the scalar field's self potential. We introduce 1+3 notation to elucidate the relation between MHD and field variables. In our approach the requirement that the scalar field be single valued leads to the quantization of a certain circulation in steps of ({Dirac_h}/2{pi}); this feature leads, in the classical limit, to the conservation of that circulation. The circulation is identical to that in Oron's generalization of Kelvin's circulation theorem to perfect MHD; we here characterize the new conserved helicity associated with it. We also demonstrate the existence for MHD of two Bernoulli-like theorems for each spacetime symmetry of the flow and geometry; one of these is pertinent to suitably defined potential flow. We exhibit the conserved quantities explicitly in the case that two symmetries are simultaneously present, and give examples. Also in this case we exhibit a new conserved MHD circulation distinct from Oron's, and provide an example.
Analysis of Magnetohydrodynamic Flow in Microfluidics
NASA Astrophysics Data System (ADS)
Panta, Yogendra; Lin, Wei
2009-11-01
Over the last three decades, numerical and experimental fluid dynamic studies have been well documented for optimization of device performance in general fluid dynamics, prediction and analysis of physiological flows, fluid-structure interactions in biological systems, and effectiveness of drug delivery systems in lab on chip devices. Magnetohydrodynamics (MHD) is a proven and a routinely used technology not only in various industries to heat, pump, stir and levitate fluids but also an innovative potential for making remarkable biosensors. Two typical pilot projects to test, analyze and optimize the MHD effects were designed. Microfluidics channels coupled with MHD in various shapes were fabricated from a thin brass sheet sandwiched between two polycarbonate sheets in which two platinum electrodes were patterned on the channel walls. Ionic solution colored with dye was introduced in the channel to visualize the fluid flow with or without the MHD. The induction and driving of fluid motion in the channel was accomplished by placing magnetic field normal to the applied electric field in order to induce Lorentz forces in the fluid contained in the channel. Experimental data and numerical results were obtained in a good agreement. Flow velocities were obtained linearly increasing with the higher magnetic flux densities. Future work will be focused on the development of MHD biosensors for chemical biology applications.
NASA Astrophysics Data System (ADS)
1980-07-01
In most of the processes, a portion of the potassium seed material is converted to a compound not containing sulfur. The potassium in this form can, when injected upstream of the MHD channel, capture the sulfur released during the combustion of coal and eliminate the need for flue gas desulfurization equipment. Criteria considered in the evaluation included cost, state of development, seed loss, power requirements, availability, durability, key component risk, environmental impact, safety, controllability, and impurities buildup.
MHD processes in the outer heliosphere
NASA Technical Reports Server (NTRS)
Burlaga, L. F.
1984-01-01
The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
Coherent Eigenmodes in Homogeneous MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2010-01-01
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
NASA Astrophysics Data System (ADS)
Chuvatin, Alexandre S.; Rudakov, Leonid I.; Kokshenev, Vladimir A.; Aranchuk, Leonid E.; Huet, Dominique; Gasilov, Vladimir A.; Krukovskii, Alexandre Yu.; Kurmaev, Nikolai E.; Fursov, Fiodor I.
2002-12-01
This work introduces an inductive energy storage (IES) scheme which aims pulsed-power conditioning at multi- MJ energies. The key element of the scheme represents an additional plasma volume, where a magnetically accelerated wire array is used for inductive current switching. This plasma acceleration volume is connected in parallel to a microsecond capacitor bank and to a 100-ns current ruse-time useful load. Simple estimates suggest that optimized scheme parameters could be reachable even when operating at ultra-high currents. We describe first proof-of-principle experiments carried out on GIT12 generator [1] at the wire-array current level of 2 MA. The obtained confirmation of the concept consists in generation of a 200 kV voltage directly at an inductive load. This load voltage value can be already sufficient to transfer the available magnetic energy into kinetic energy of a liner at this current level. Two-dimensional modeling with the radiational MHD numerical tool Marple [2] confirms the development of inductive voltage in the system. However, the average voltage increase is accompanied by short-duration voltage drops due to interception of the current by the low-density upstream plasma. Upon our viewpoint, this instability of the current distribution represents the main physical limitation to the scheme performance.
DIFFUSIVE ACCELERATION OF PARTICLES AT OBLIQUE, RELATIVISTIC, MAGNETOHYDRODYNAMIC SHOCKS
Summerlin, Errol J.; Baring, Matthew G. E-mail: baring@rice.edu
2012-01-20
Diffusive shock acceleration (DSA) at relativistic shocks is expected to be an important acceleration mechanism in a variety of astrophysical objects including extragalactic jets in active galactic nuclei and gamma-ray bursts. These sources remain good candidate sites for the generation of ultrahigh energy cosmic rays. In this paper, key predictions of DSA at relativistic shocks that are germane to the production of relativistic electrons and ions are outlined. The technique employed to identify these characteristics is a Monte Carlo simulation of such diffusive acceleration in test-particle, relativistic, oblique, magnetohydrodynamic (MHD) shocks. Using a compact prescription for diffusion of charges in MHD turbulence, this approach generates particle angular and momentum distributions at any position upstream or downstream of the shock. Simulation output is presented for both small angle and large angle scattering scenarios, and a variety of shock obliquities including superluminal regimes when the de Hoffmann-Teller frame does not exist. The distribution function power-law indices compare favorably with results from other techniques. They are found to depend sensitively on the mean magnetic field orientation in the shock, and the nature of MHD turbulence that propagates along fields in shock environs. An interesting regime of flat-spectrum generation is addressed; we provide evidence for it being due to shock drift acceleration, a phenomenon well known in heliospheric shock studies. The impact of these theoretical results on blazar science is outlined. Specifically, Fermi Large Area Telescope gamma-ray observations of these relativistic jet sources are providing significant constraints on important environmental quantities for relativistic shocks, namely, the field obliquity, the frequency of scattering, and the level of field turbulence.
Resonance Broadening and Heating of Charged Particles in Magnetohydrodynamic Turbulence
NASA Astrophysics Data System (ADS)
Lynn, Jacob W.; Parrish, Ian J.; Quataert, Eliot; Chandran, Benjamin D. G.
2012-10-01
The heating, acceleration, and pitch-angle scattering of charged particles by magnetohydrodynamic (MHD) turbulence are important in a wide range of astrophysical environments, including the solar wind, accreting black holes, and galaxy clusters. We simulate the interaction of high-gyrofrequency test particles with fully dynamical simulations of subsonic MHD turbulence, focusing on the parameter regime with ? ~ 1, where ? is the ratio of gas to magnetic pressure. We use the simulation results to calibrate analytical expressions for test particle velocity-space diffusion coefficients and provide simple fits that can be used in other work. The test particle velocity diffusion in our simulations is due to a combination of two processes: interactions between particles and magnetic compressions in the turbulence (as in linear transit-time damping; TTD) and what we refer to as Fermi Type-B (FTB) interactions, in which charged particles moving on field lines may be thought of as beads sliding along moving wires. We show that test particle heating rates are consistent with a TTD resonance that is broadened according to a decorrelation prescription that is Gaussian in time (but inconsistent with Lorentzian broadening due to an exponential decorrelation function, a prescription widely used in the literature). TTD dominates the heating for vs Gt vA (e.g., electrons), where vs is the thermal speed of species s and vA is the Alfvn speed, while FTB dominates for vs Lt vA (e.g., minor ions). Proton heating rates for ? ~ 1 are comparable to the turbulent cascade rate. Finally, we show that velocity diffusion of collisionless, large gyrofrequency particles due to large-scale MHD turbulence does not produce a power-law distribution function.
Note: Tangential x-ray diagnosis for investigating fast MHD events in EAST tokamak
Li Erzhong; Hu Liqun; Chen Kaiyun; Zhang Jizong; Chen Yiebin; Zhou Ruijie; Gan Kaifu; Liu Yong
2010-10-15
A tangential x-ray diagnosis has been installed in the experimental advanced superconducting tokamakvacuum vessel for the study of fast magnetohydrodynamics (MHD) events. This system is based on absolute x-ray ultraviolet detectors with a collimator which is processed by laser machine. The first experimental results have proved its ability to measure the small-scale and transient MHD perturbations.
Magnetohydrodynamic Propulsion for the Classroom
NASA Astrophysics Data System (ADS)
Font, Gabriel I.; Dudley, Scott C.
2004-10-01
The cinema industry can sometimes prove to be an ally when searching for material with which to motivate students to learn physics. Consider, for example, the electromagnetic force on a current in the presence of a magnetic field. This phenomenon is at the heart of magnetohydrodynamic (MHD) propulsion systems. A submarine employing this type of propulsion was immortalized in the movie Hunt for Red October. While mentioning this to students certainly gets their attention, it often elicits comments that it is only fiction and not physically possible. Imagine their surprise when a working system is demonstrated! It is neither difficult nor expensive to construct a working system that can be demonstrated in the front of a classroom.2 In addition, all aspects of the engineering hurdles that must be surmounted and myths concerning this "silent propulsion" system are borne out in a simple apparatus. This paper details how to construct an inexpensive MHD propulsion boat that can be demonstrated for students in the classroom.
Advanced Coal-Based Power Generations
NASA Technical Reports Server (NTRS)
Robson, F. L.
1982-01-01
Advanced power-generation systems using coal-derived fuels are evaluated in two-volume report. Report considers fuel cells, combined gas- and steam-turbine cycles, and magnetohydrodynamic (MHD) energy conversion. Presents technological status of each type of system and analyzes performance of each operating on medium-Btu fuel gas, either delivered via pipeline to powerplant or generated by coal-gasification process at plantsite.
Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft
Myrabo, L.N.; Rosa, R.J.
2004-03-30
Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant 'Mercury' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a 'tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off and landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic 'mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond 'idle' power, or virtually 'disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely 'green' and independent of Earth's limited fossil fuel reserves.
Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft
NASA Astrophysics Data System (ADS)
Myrabo, L. N.; Rosa, R. J.
2004-03-01
Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant ``Mercury'' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a `tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off & landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic `mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond `idle' power, or virtually `disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely `green' and independent of Earth's limited fossil fuel reserves.
Petrick, Michael (Joliet, IL); Pierson, Edward S. (Chicago, IL); Schreiner, Felix (Mokena, IL)
1980-01-01
According to the present invention, coal combustion gas is the primary working fluid and copper or a copper alloy is the electrodynamic fluid in the MHD generator, thereby eliminating the heat exchangers between the combustor and the liquid-metal MHD working fluids, allowing the use of a conventional coalfired steam bottoming plant, and making the plant simpler, more efficient and cheaper. In operation, the gas and liquid are combined in a mixer and the resulting two-phase mixture enters the MHD generator. The MHD generator acts as a turbine and electric generator in one unit wherein the gas expands, drives the liquid across the magnetic field and thus generates electrical power. The gas and liquid are separated, and the available energy in the gas is recovered before the gas is exhausted to the atmosphere. Where the combustion gas contains sulfur, oxygen is bubbled through a side loop to remove sulfur therefrom as a concentrated stream of sulfur dioxide. The combustor is operated substoichiometrically to control the oxide level in the copper.
MHD stability of incompressible coronal loops with radiative energy loss
NASA Technical Reports Server (NTRS)
An, C.-H.
1983-01-01
Previous studies of the magnetohydrodynamic (MHD) stability of solar coronal loops have not taken into account the effects of radiative energy loss in the energy equation. However, since coronal loops continuously lose energy by radiation and heat conduction, it is important to understand how these energy loss mechanisms affect MHD stability. We investigate the problem assuming that a magnetic loop has cylindrical geometry. As a first step, stability is studied for a localized mode, and the result is applied to a specific equilibrium. We find that the radiative energy loss effect not only changes the growth rate of ideally unstable modes, but also alters the stability boundary predicted by ideal MHD theory.
MHD augmented chemical rocket propulsion for space applications
NASA Astrophysics Data System (ADS)
Schulz, R. J.; Chapman, J. N.; Rhodes, R. P.
1992-07-01
A performance analysis is carried out of a magnetohydrodynamic (MHD) augmented chemical thruster (based on a gaseous hydrogen-oxygen system) for space applications such as orbit transfer. The mathematical model used in the analysis is a one-dimensional flow model using equilibrium chemistry for the combustor, choked nozzle, and MHD channel portions of the system, and chemical nonequilibrium kinetics for the high area-ratio gas dynamic nozzle portion of the system. The performance of the chemical-MHD-augmented thruster is compared with that of a pure electric thruster of the same specific impulse level.
Broken Symmetry and Coherent Structure in MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2007-01-01
Absolute equilibrium ensemble theory for ideal homogeneous magnetohydrodynamic (MHD) turbulence is fairly well developed. Theory and Simulation indicate that ideal MHD turbulence non-ergodic and contains coherent structure. The question of applicability real (i.e., dissipative) MHD turbulence is examined. Results from several very long time numerical simulations on a 64(exp 3) grid are presented. It is seen that coherent structure begins to form before decay dominates over nonlinearity. The connection with inverse spectral cascades and selective decay will also be discussed.
Chan Chikwan; Psaltis, Dimitrios; Oezel, Feryal
2009-07-20
Accretion disks are three-dimensional, turbulent, often self-gravitating, magnetohydrodynamic (MHD) flows, which can be modeled with numerical simulations. In this paper, we present a new algorithm that is based on a spectral decomposition method to simulate such flows. Because of the high order of the method, we can solve the induction equation in terms of the magnetic vector potential and, therefore, ensure trivially that the magnetic fields in the numerical solution are divergence free. The spectral method also suffers minimally from numerical dissipation and allows for an easy implementation of models for subgrid physics. Both properties make our method ideal for studying MHD turbulent flows such as those found in accretion disks around compact objects. We verify our algorithm with a series of standard tests and use it to show the development of MHD turbulence in a simulation of an accretion disk. Finally, we study the evolution and saturation of the power spectrum of MHD turbulence driven by the magnetorotational instability.
Samim Anghaie
2002-08-13
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.
ANALYTIC APPROXIMATE SEISMOLOGY OF PROPAGATING MAGNETOHYDRODYNAMIC WAVES IN THE SOLAR CORONA
Goossens, M.; Soler, R.; Arregui, I.
2012-12-01
Observations show that propagating magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. The technique of MHD seismology uses the wave observations combined with MHD wave theory to indirectly infer physical parameters of the solar atmospheric plasma and magnetic field. Here, we present an analytical seismological inversion scheme for propagating MHD waves. This scheme uses the observational information on wavelengths and damping lengths in a consistent manner, along with observed values of periods or phase velocities, and is based on approximate asymptotic expressions for the theoretical values of wavelengths and damping lengths. The applicability of the inversion scheme is discussed and an example is given.
A numerical study of low frequency wave in Hall MHD reconnection with various plasma
NASA Astrophysics Data System (ADS)
Li, Y.; Jin, S. P.; Yang, H. A.; Zhou, G. C.; Liu, S. L.
Magnetic reconnection with various plasma beta the ratio of plasma pressure to the magnetic pressure is studied using a 2 5 dimensional Hall magnetohydrodynamics MHD code developed from a multi-step implicit scheme The initial state of the Hall MHD simulation is an equilibrium Harris sheet with a zero guide field i e B y0 0 at t 0 Driven by a constant boundary inflow a quasi--steady fast reconnection occurs in the plasma with a low uniform resistivity The reconnection rate partial A partial A partial t partial t vert st in the quasi--steady state is in the range of 0 15 partial A partial A partial t partial t vert st 0 095 for the cases with plasma beta ranging 0 5 beta 6 5 In this report the waves in the Hall MHD reconnection are investigated The time series of the out-of-plane magnetic field B y and the velocity components V x V z in the x z plane at the given points are transferred into the power spectrums by the Fast Fourier Transform FFT for the cases with various plasma beta The results indicate that the frequencies of the B y V x V z power spectrums are in the range of omega ci omega 8 omega ci where omega ci is the proton cyclotron frequency A shift of low frequency and the energy reduction in the power spectrum can be found as the plasma beta increases Using the Minimum Variance Analysis
Barnes, P.R.; Vance, E.F.
1992-01-01
A nuclear detonation at altitudes several hundred kilometers above the earth will severely distort the earth's magnetic field and result in a strong magnetohyrodynamic electromagnetic pulse (MHD-EMP). The geomagnetic disturbance interacts with the soil to induce current and horizontal electric gradients. The geomagnetic disturbance interacts with the soil to induced current and horizontal electric gradients in the earth. MHD-EMP, also called E3 since it is the third component of the high-altitude EMP (HEMP), lasts over 100 s after the exoatmospheric burst. MHD-EMP is similar to solar geomagnetic storms in it's global and low frequency (less than 1 Hz) nature except that E3 can be much more intense with a far shorter duration. When the MHD-EMP gradients are integrated over great distances by power lines, communication cables, or other long conductors, the induced voltages are significant. (The horizontal gradients in the soil are too small to induce major responses by local interactions with facilities.) The long pulse waveform for MHD-EMP-induced currents on long lines has a peak current of 200 A and a time-to-half-peak of 100 s. If this current flows through transformer windings, it can saturate the magnetic circuit and cause 60 Hz harmonic production. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building and the commercial power harmonics and voltage swings must be addressed. The transfer switch would be expected to respond to the voltage fluctuations as long as the harmonics have not interfered with the switch control circuitry. The major sources of MHD-EMP induced currents are the commercial power lines and neutral; neutral current indirect coupling to the facility power or ground system via the metal fence, powered gate, parking lights, etc; metal water pipes; phone lines; and other long conductors that enter or come near the facility. The major source of harmonics is the commercial power system.
Makwana, K. D. Cattaneo, F.; Zhdankin, V.; Li, H.; Daughton, W.
2015-04-15
Simulations of decaying magnetohydrodynamic (MHD) turbulence are performed with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k{sub ⊥}{sup −1.3}. The kinetic code shows a spectral slope of k{sub ⊥}{sup −1.5} for smaller simulation domain, and k{sub ⊥}{sup −1.3} for larger domain. We estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. This work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.
NASA Astrophysics Data System (ADS)
Makwana, K. D.; Zhdankin, V.; Li, H.; Daughton, W.; Cattaneo, F.
2015-04-01
Simulations of decaying magnetohydrodynamic (MHD) turbulence are performed with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvn waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k?-1.3 . The kinetic code shows a spectral slope of k?-1.5 for smaller simulation domain, and k?-1.3 for larger domain. We estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. This work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.
Thermodynamics of magnetohydrodynamic flows with axial symmetry
Leprovost, N.; Dubrulle, B.; Chavanis, P-H.
2005-03-01
We present strategies based upon optimization principles in the case of the axisymmetric equations of magnetohydrodynamics (MHD). We derive the equilibrium state by using a minimum energy principle under the constraints of the MHD axisymmetric equations. We also propose a numerical algorithm based on a maximum energy dissipation principle to compute in a consistent way the nonlinearly dynamically stable equilibrium states. Then, we develop the statistical mechanics of such flows and recover the same equilibrium states giving a justification of the minimum energy principle. We find that fluctuations obey a Gaussian shape and we make the link between the conservation of the Casimirs on the coarse-grained scale and the process of energy dissipation. We contrast these results with those of two-dimensional hydrodynamical turbulence where the equilibrium state maximizes a H function at fixed energy and circulation and where the fluctuations are nonuniversal.
Advected Invariants in Magnetohydrodynamics and Gas Dynamics
NASA Astrophysics Data System (ADS)
Webb, G. M.; Hu, Q.; McKenzie, J. F.; Dasgupta, B.; Zank, G. P.
2014-05-01
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.
Magnetohydrodynamic Modeling of the Jovian Magnetosphere
NASA Technical Reports Server (NTRS)
Walker, Raymond
2005-01-01
Under this grant we have undertaken a series of magnetohydrodynamic (MHD) simulation and data analysis studies to help better understand the configuration and dynamics of Jupiter's magnetosphere. We approached our studies of Jupiter's magnetosphere in two ways. First we carried out a number of studies using our existing MHD code. We carried out simulation studies of Jupiter s magnetospheric boundaries and their dependence on solar wind parameters, we studied the current systems which give the Jovian magnetosphere its unique configuration and we modeled the dynamics of Jupiter s magnetosphere following a northward turning of the interplanetary magnetic field (IMF). Second we worked to develop a new simulation code for studies of outer planet magnetospheres.
MAGNETOHYDRODYNAMIC SHALLOW WATER WAVES: LINEAR ANALYSIS
Heng, Kevin; Spitkovsky, Anatoly E-mail: anatoly@astro.princeton.ed
2009-10-01
We present a linear analysis of inviscid, incompressible, magnetohydrodynamic (MHD) shallow water systems. In spherical geometry, a generic property of such systems is the existence of five wave modes. Three of them (two magneto-Poincare modes and one magneto-Rossby mode) are previously known. The other two wave modes are strongly influenced by the magnetic field and rotation, and have substantially lower angular frequencies; as such, we term them 'magnetostrophic modes'. We obtain analytical functions for the velocity, height, and magnetic field perturbations in the limit that the magnitude of the MHD analogue of Lamb's parameter is large. On a sphere, the magnetostrophic modes reside near the poles, while the other modes are equatorially confined. Magnetostrophic modes may be an ingredient in explaining the frequency drifts observed in Type I X-ray bursts from neutron stars.
Numerical Methods for Radiation Magnetohydrodynamics in Astrophysics
Klein, R I; Stone, J M
2007-11-20
We describe numerical methods for solving the equations of radiation magnetohydrodynamics (MHD) for astrophysical fluid flow. Such methods are essential for the investigation of the time-dependent and multidimensional dynamics of a variety of astrophysical systems, although our particular interest is motivated by problems in star formation. Over the past few years, the authors have been members of two parallel code development efforts, and this review reflects that organization. In particular, we discuss numerical methods for MHD as implemented in the Athena code, and numerical methods for radiation hydrodynamics as implemented in the Orion code. We discuss the challenges introduced by the use of adaptive mesh refinement in both codes, as well as the most promising directions for future developments.
MHD--Developing New Technology to Meet the Energy Crisis
ERIC Educational Resources Information Center
Fitch, Sandra S.
1978-01-01
Magnetohydrodynamics is a technology that could utilize the nation's most abundant fossil fuel and produce electrical energy more efficiently and cleanly than present-day turbines. A national research and development program is ongoing in Butte, Montana at the Montana Energy and MHD Research and Development Institute (MERDI). (Author/RK)
On the question of hysteresis in Hall magnetohydrodynamic reconnection
Sullivan, Brian P.; Bhattacharjee, A.; Huang Yimin
2010-11-15
Controversy has been raised regarding the cause of hysteresis, or bistability, of solutions to the equations that govern the geometry of the reconnection region in Hall magnetohydrodynamic (MHD) systems. This brief communication presents a comparison of the frameworks within which this controversy has arisen and illustrates that the Hall MHD hysteresis originally discovered numerically by Cassak et al. [Phys. Rev. Lett. 95, 235002 (2005)] is a different phenomenon from that recently reported by Zocco et al. [Phys. Plasmas 16, 110703 (2009)] on the basis of analysis and simulations in electron MHD with finite electron inertia. We demonstrate that the analytic prediction of hysteresis in EMHD does not describe or explain the hysteresis originally reported in Hall MHD, which is shown to persist even in the absence of electron inertia.
Toward textbook multigrid efficiency for fully implicit resistive magnetohydrodynamics
Adams, Mark F.; Samtaney, Ravi; Brandt, Achi
2010-09-01
Multigrid methods can solve some classes of elliptic and parabolic equations to accuracy below the truncation error with a work-cost equivalent to a few residual calculations - so-called 'textbook' multigrid efficiency. We investigate methods to solve the system of equations that arise in time dependent magnetohydrodynamics (MHD) simulations with textbook multigrid efficiency. We apply multigrid techniques such as geometric interpolation, full approximate storage, Gauss-Seidel smoothers, and defect correction for fully implicit, nonlinear, second-order finite volume discretizations of MHD. We apply these methods to a standard resistive MHD benchmark problem, the GEM reconnection problem, and add a strong magnetic guide field, which is a critical characteristic of magnetically confined fusion plasmas. We show that our multigrid methods can achieve near textbook efficiency on fully implicit resistive MHD simulations.
Toward textbook multigrid efficiency for fully implicit resistive magnetohydrodynamics
Adams, Mark F.; Samtaney, Ravi; Brandt, Achi
2010-09-01
Multigrid methods can solve some classes of elliptic and parabolic equations to accuracy below the truncation error with a work-cost equivalent to a few residual calculations so-called textbook multigrid efficiency. We investigate methods to solve the system of equations that arise in time dependent magnetohydrodynamics (MHD) simulations with textbook multigrid efficiency. We apply multigrid techniques such as geometric interpolation, full approximate storage, GaussSeidel smoothers, and defect correction for fully implicit, nonlinear, second-order finite volume discretizations of MHD. We apply these methods to a standard resistive MHD benchmark problem, the GEM reconnection problem, and add a strong magnetic guide field, which is a critical characteristic of magnetically confined fusion plasmas. We show that our multigrid methods can achieve near textbook efficiency on fully implicit resistive MHD simulations.
Spontaneous chiral symmetry breaking of Hall magnetohydrodynamic turbulence.
Meyrand, Romain; Galtier, Sbastien
2012-11-01
Hall magnetohydrodynamics (MHD) is investigated through three-dimensional direct numerical simulations. We show that the Hall effect induces a spontaneous chiral symmetry breaking of the turbulent dynamics. The normalized magnetic polarization is introduced to separate the right- (R) and left-handed (L) fluctuations. A classical k(-7/3) spectrum is found at small scales for R magnetic fluctuations which corresponds to the electron MHD prediction. A spectrum compatible with k(-11/3) is obtained at large-scales for the L magnetic fluctuations; we call this regime the ion MHD. These results are explained heuristically by rewriting the Hall MHD equations in a succinct vortex dynamical form. Applications to solar wind turbulence are discussed. PMID:23215387
Properties of balanced and imbalanced relativistic alfvnic magnetohydrodynamic turbulence
NASA Astrophysics Data System (ADS)
Cho, Jungyeon
2014-09-01
When the magnetic field is so strong that the magnetic energy density is much larger than that of matter, magnetic perturbations propagate along the magnetic field lines, and the speed of propagation approaches the speed of light. As in the non-relativistic case, counter-traveling waves in this relativistic limit can interact and generate turbulence. In the present paper, we discuss the properties of the magnetohydrodynamic (MHD) turbulence generated by such interactions. First, we discuss the scaling relations for driven, balanced, relativistic MHD turbulence, in which the amplitudes of counter-traveling wave packets are similar. Second, we discuss the scaling relations of imbalanced relativistic MHD turbulence, in which the amplitudes of counter-traveling wave packets are different. Numerical simulations show that the scaling relations of relativistic MHD turbulence for both cases are very similar to those for their non-relativistic counterparts.
Toward textbook multigrid efficiency for fully implicit resistive magnetohydrodynamics
Adams, Mark F.; Samtaney, Ravi; Brandt, Achi
2010-09-01
Multigrid methods can solve some classes of elliptic and parabolic equations to accuracy below the truncation error with a work-cost equivalent to a few residual calculations – so-called ‘‘textbook” multigrid efficiency. We investigate methods to solve the system of equations that arise in time dependent magnetohydrodynamics (MHD) simulations with textbook multigrid efficiency. We apply multigrid techniques such as geometric interpolation, full approximate storage, Gauss–Seidel smoothers, and defect correction for fully implicit, nonlinear, second-order finite volume discretizations of MHD. We apply these methods to a standard resistive MHD benchmark problem, the GEM reconnection problem, and add a strong magnetic guide field,more » which is a critical characteristic of magnetically confined fusion plasmas. We show that our multigrid methods can achieve near textbook efficiency on fully implicit resistive MHD simulations.« less
Toward textbook multigrid efficiency for fully implicit resistive magnetohydrodynamics
Adams, Mark F.; Samtaney, Ravi; Brandt, Achi
2013-12-14
Multigrid methods can solve some classes of elliptic and parabolic equations to accuracy below the truncation error with a work-cost equivalent to a few residual calculations – so-called “textbook” multigrid efficiency. We investigate methods to solve the system of equations that arise in time dependent magnetohydrodynamics (MHD) simulations with textbook multigrid efficiency. We apply multigrid techniques such as geometric interpolation, full approximate storage, Gauss-Seidel smoothers, and defect correction for fully implicit, nonlinear, second-order finite volume discretizations of MHD. We apply these methods to a standard resistive MHD benchmark problem, the GEM reconnection problem, and add a strong magnetic guide field, which is a critical characteristic of magnetically confined fusion plasmas. We show that our multigrid methods can achieve near textbook efficiency on fully implicit resistive MHD simulations.
Zaininger, H.W.
1984-08-01
A high altitude nuclear burst, detonated at a height of 50 km or more, causes two types of electromagnetic pulses (EMP) - high altitude EMP (HEMP) and magnetohydrodynamic EMP (MHD-EMP). This high altitude EMP scenario is of principal concern when assessing the effects of EMP on electric power systems, because the total United States can be simultaneously illuminated by HEMP and MHD-EMP can cover a large area of up to several hundred kilometers in diameter. The purpose of this project was first to define typical electrical power system characteristics for EMP analysis, and second, to determine reasonable worst case EMP induced surges on overhead electric power system transmission and distribution lines for reasonable assumptions, using unclassified HEMP and MHD-EMP electric field waveforms.
Lattice Boltzmann model for resistive relativistic magnetohydrodynamics.
Mohseni, F; Mendoza, M; Succi, S; Herrmann, H J
2015-08-01
In this paper, we develop a lattice Boltzmann model for relativistic magnetohydrodynamics (MHD). Even though the model is derived for resistive MHD, it is shown that it is numerically robust even in the high conductivity (ideal MHD) limit. In order to validate the numerical method, test simulations are carried out for both ideal and resistive limits, namely the propagation of Alfvén waves in the ideal MHD and the evolution of current sheets in the resistive regime, where very good agreement is observed comparing to the analytical results. Additionally, two-dimensional magnetic reconnection driven by Kelvin-Helmholtz instability is studied and the effects of different parameters on the reconnection rate are investigated. It is shown that the density ratio has a negligible effect on the magnetic reconnection rate, while an increase in shear velocity decreases the reconnection rate. Additionally, it is found that the reconnection rate is proportional to σ-1/2, σ being the conductivity, which is in agreement with the scaling law of the Sweet-Parker model. Finally, the numerical model is used to study the magnetic reconnection in a stellar flare. Three-dimensional simulation suggests that the reconnection between the background and flux rope magnetic lines in a stellar flare can take place as a result of a shear velocity in the photosphere. PMID:26382548
Linear wave propagation in relativistic magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Keppens, R.; Meliani, Z.
2008-10-01
The properties of linear Alfvén, slow, and fast magnetoacoustic waves for uniform plasmas in relativistic magnetohydrodynamics (MHD) are discussed, augmenting the well-known expressions for their phase speeds with knowledge on the group speed. A 3+1 formalism is purposely adopted to make direct comparison with the Newtonian MHD limits easier and to stress the graphical representation of their anisotropic linear wave properties using the phase and group speed diagrams. By drawing these for both the fluid rest frame and for a laboratory Lorentzian frame which sees the plasma move with a three-velocity having an arbitrary orientation with respect to the magnetic field, a graphical view of the relativistic aberration effects is obtained for all three MHD wave families. Moreover, it is confirmed that the classical Huygens construction relates the phase and group speed diagram in the usual way, even for the lab frame viewpoint. Since the group speed diagrams correspond to exact solutions for initial conditions corresponding to a localized point perturbation, their formulae and geometrical construction can serve to benchmark current high-resolution algorithms for numerical relativistic MHD.
Magnetohydrodynamic Augmentation of Pulse Detonation Engines
NASA Astrophysics Data System (ADS)
Zeineh, Christopher; Cole, Lord; Karagozian, Ann
2010-11-01
Pulse detonation engines (PDEs) are the focus of increasing attention due to their potentially superior performance over constant pressure engines. Yet due to its unsteady chamber pressure, the PDE system will either be over- or under-expanded for the majority of the cycle, with energy being used without maximum gain. Magnetohydrodynamic (MHD) augmentation offers the opportunity to extract energy and apply it to a separate stream where the net thrust will be increased. With MHD augmentation, such as in the Pulse Detonation Rocket-Induced MHD Ejector (PDRIME) concept, energy could be extracted from the high speed portion of the system, e.g., through a generator in the nozzle, and then applied directly to another flow or portion of the flow as a body force. The present high resolution numerical simulations explore the flow evolution and potential performance of such propulsion systems. An additional magnetic piston applying energy in the PDE chamber can also act in concert with the PDRIME for separate thrust augmentation. Results show that MHD can indeed influence the flow and pressure fields in a beneficial way in these configurations, with potential performance gains under a variety of flight and operating conditions. There are some challenges associated with achieving these gains, however, suggesting further optimization is required.
Magnetohydrodynamics on an unstructured moving grid
NASA Astrophysics Data System (ADS)
Pakmor, Ruediger; Bauer, Andreas; Springel, Volker
2011-12-01
Magnetic fields play an important role in astrophysics on a wide variety of scales, ranging from the Sun and compact objects to galaxies and galaxy clusters. Here we discuss a novel implementation of ideal magnetohydrodynamics (MHD) in the moving-mesh code AREPO which combines many of the advantages of Eulerian and Lagrangian methods in a single computational technique. The employed grid is defined as the Voronoi tessellation of a set of mesh-generating points which can move along with the flow, yielding an automatic adaptivity of the mesh and a substantial reduction of advection errors. Our scheme solves the MHD Riemann problem in the rest frame of the Voronoi interfaces using the HLLD Riemann solver. To satisfy the divergence constraint of the magnetic field in multiple dimensions, the Dedner divergence cleaning method is applied. In a set of standard test problems, we show that the new code produces accurate results and that the divergence of the magnetic field is kept sufficiently small to closely preserve the correct physical solution. We also apply the code to two first application problems, namely supersonic MHD turbulence and the spherical collapse of a magnetized cloud. We verify that the code is able to handle both problems well, demonstrating the applicability of this MHD version of AREPO to a wide range of problems in astrophysics.
Laser production and heating of plasma for MHD application
NASA Technical Reports Server (NTRS)
Jalufka, N. W.
1988-01-01
Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed 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.
Laser production and heating of plasma for MHD application
Jalufka, N.W.
1988-03-01
Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO/sub 2/ laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO/sub 2/ laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO/sub 2/ laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.
Magnetohydrodynamic propulsion using on-board sources
NASA Astrophysics Data System (ADS)
Martin, James A.
1998-01-01
Magnetohydrodynamics is considered to extract power from flow and to inset power into flow at different points in propulsion systems that might be useful for advanced Earth-to-orbit vehicles. No beamed power is considered, and so the power is all generated from on-board sources. An ideal analysis is used as the first step toward deciding which concepts to examine further. The airbreathing engine concept that uses magnetohydrodynamics to replace the rotating machinery in a turbojet engine provides the most attractive results.
NASA Astrophysics Data System (ADS)
Kisiel, T.; Soida, M.
2007-12-01
The rocket technology dates back as far as medieval China. Used initially for entertainment and religious practices over time rockets evolved into weapons and finally into means of transportation. Today, we are nearing the top of the rockets' capabilities. Although, for now they are the only way for us to send anything into space we are becoming more and more aware of the limitations of this technology. It is essential that we invent other means of propelling probes and other interplanetary vehicles through space. The authors had performed a series of magnetohydrodynamic simulations using the University of Chicago's Flash package to find out whether the interactions between the Solar Wind and the conducting ring with the electric current would occur. The MHD simulations gave the results similar to the monte-carlo calculations performed by dr Charles Danforth from the University of Colorado. It is the authors' conclusion that the promising results should encourage further study of the phenomenon and the possibility of using it in practice.
NASA Astrophysics Data System (ADS)
Noguchi, Koichi
2001-09-01
Structure formation in various astronomical systems through magnetohydrodynamical (MHD) instabilities has been investigated. The effect of magnetic field enhancement in sheared flows is studied as the eigenmode problem in a non-self-adjoint system, and new mathematical and physical aspects of the instability are shown. The mechanism for the faster structure formation in a protoplanetary disk with MHD instabilities is suggested with linear analysis and simulation. Experiments to simulate the plasmas of protoplanetary and active galactic nuclei are also suggested. The coupling of magnetic field enhancement and magnetic buoyancy has been studied and mode coupling of two instabilities are shown. The stability of nonaxisymmetric perturbations in a differentially rotating astrophysical accretion disk is analyzed by fully incorporating the properties of shear flows. The magnetorotational instability has been investigated as the most promising instability to explain anomalous angular momentum transfer in accretion disks. The apparent narrow window of the age difference of the Sun and the Earth is one of the most difficult problems in the planetary formation theory. The magnetorotational, Parker, and kinematic dynamo instabilities under the presence of magnetic fields in the protoplanetary disk can greatly facilitate the formation of density structures that may provide seeds of protoplanetesimals prior to the onset of the gravitational Jeans instability. The unstable eigenmodes with complex and pure imaginary eigenvalues without any artificial disk edge boundaries is shown to be discrete. The nonlocal behavior of eigenmodes in the vicinity of Alfvn singularities at ? D = +/-?A is investigated mathematically and physically, where ?D is the Doppler- shifted wave frequency and ?A = k?vA is the Alfvn frequency. The effects of the Parker, magnetorotational (Balbus- Hawley), and kinematic dynamo instabilities are evaluated by comparing the properties of these instabilities in protoplanetary disks. The mass spectra of aggregated density structures are calculated by the above mechanism in the radial direction for axisymmetric MHD torus equilibrium and power-law density profile models. The coupling of the magnetorotational and the Parker instabilities is studied here by three-dimensional MHD simulations. The coupling of these instabilities is analyzed linearly, and preliminary results are shown. (Abstract shortened by UMI.)
Classical and semirelativistic magnetohydrodynamics with anisotropic ion pressure
NASA Astrophysics Data System (ADS)
Meng, Xing; Tth, Gbor; Sokolov, Igor V.; Gombosi, Tamas I.
2012-05-01
We study the magnetohydrodynamics (MHD) equations with anisotropic ion pressure and isotropic electron pressure under both the classical and semirelativistic approximations in order to develop a numerical model. The dispersion relation as well as the characteristic wave speeds are derived. In addition to the exact wave speed solutions, we also provide efficient approximate formulas for the semirelativistic magnetosonic speeds. The equations are discretized with the Rusanov and Harten-Lax-van Leer numerical schemes and implemented into the BATS-R-US MHD code. We perform a set of verification tests.
Magnetohydrodynamic waves and coronal seismology: an overview of recent results.
De Moortel, Ineke; Nakariakov, Valery M
2012-07-13
Recent observations have revealed that magnetohydrodynamic (MHD) waves and oscillations are ubiquitous in the solar atmosphere, with a wide range of periods. We give a brief review of some aspects of MHD waves and coronal seismology that have recently been the focus of intense debate or are newly emerging. In particular, we focus on four topics: (i) the current controversy surrounding propagating intensity perturbations along coronal loops, (ii) the interpretation of propagating transverse loop oscillations, (iii) the ongoing search for coronal (torsional) Alfvén waves, and (iv) the rapidly developing topic of quasi-periodic pulsations in solar flares. PMID:22665899
Ramrus, A.
1986-02-01
Objective of the study was to create conceptual designs of high voltage pulsers capable of simulating two types of electromagnetic pulses (EMPs) caused by a high-altitude nuclear burst; the slow rise time magnetohydrodynamic (MHD-EMP) and the fast rise time high-altitude EMP (HEMP). The pulser design was directed towards facilities capable of performing EMP vulnerability testing of components used in the national electric power system.
NASA Astrophysics Data System (ADS)
Ngwira, Chigomezyo M.; Pulkkinen, Antti; Kuznetsova, Maria M.; Glocer, Alex
2014-06-01
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.
NASA Technical Reports Server (NTRS)
Ngwira, Chigomezyo M.; Pulkkinen, Antti; Kuznetsova, Maria M.; Glocer, Alex
2014-01-01
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 approx. = -1600 nT.
NASA Technical Reports Server (NTRS)
Montgomery, David
1988-01-01
Three areas of study in MHD turbulence are considered. These are the turbulent relaxation of the toroidal Z pinch, density fluctuations in MHD fluids, and MHD cellular automata. A Boolean computer game that updates a cellular representation in parallel and that has macroscopic averages converging to solutions of the two-dimensional MHD equations is discussed.
Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence
Donato, S.; Servidio, S.; Carbone, V.; Dmitruk, P.; Shay, M. A.; Matthaeus, W. H.; Cassak, P. A.
2012-09-15
The statistical study of magnetic reconnection events in two-dimensional turbulence has been performed by comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics (HMHD). The analysis reveals that the Hall term plays an important role in turbulence, in which magnetic islands simultaneously reconnect in a complex way. In particular, an increase of the Hall parameter, the ratio of ion skin depth to system size, broadens the distribution of reconnection rates relative to the MHD case. Moreover, in HMHD the local geometry of the reconnection region changes, manifesting bifurcated current sheets and quadrupolar magnetic field structures in analogy to laminar studies, leading locally to faster reconnection processes in this case of reconnection embedded in turbulence. This study supports the idea that the global rate of energy dissipation is controlled by the large scale turbulence, but suggests that the distribution of the reconnection rates within the turbulent system is sensitive to the microphysics at the reconnection sites.
Efficient acceleration of relativistic magnetohydrodynamic jets
NASA Astrophysics Data System (ADS)
Toma, Kenji; Takahara, Fumio
2013-08-01
Relativistic jets in active galactic nuclei, galactic microquasars, and gamma-ray bursts are widely considered to be magnetohydrodynamically driven by black hole accretion systems, although the conversion mechanism from the Poynting into the particle kinetic energy flux is still open. Recent detailed numerical and analytical studies of global structures of steady, axisymmetric magnetohydrodynamic (MHD) flows with specific boundary conditions have not reproduced as rapid an energy conversion as required by observations. In order to find more suitable boundary conditions, we focus on the flow along a poloidal magnetic field line just inside the external boundary, without treating the transfield force balance in detail. We find some examples of the poloidal field structure and corresponding external pressure profile for an efficient and rapid energy conversion as required by observations, and that the rapid acceleration requires a rapid decrease of the external pressure above the accretion disk. We also clarify the differences between the fast magnetosonic point of the MHD flow and the sonic point of the de Laval nozzle.
Computational Methods for Ideal Magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Kercher, Andrew D.
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.
Magnetic levitation and MHD propulsion
NASA Astrophysics Data System (ADS)
Tixador, P.
1994-04-01
Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried out in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ...) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. Depuis quelques années nous assistons 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.
Dipole Alignment in Rotating MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.; Fu, Terry; Morin, Lee
2012-01-01
We present numerical results from long-term CPU and GPU simulations of rotating, homogeneous, magnetohydrodynamic (MHD) turbulence, and discuss their connection to the spherically bounded case. We compare our numerical results with a statistical theory of geodynamo action that has evolved from the absolute equilibrium ensemble theory of ideal MHD turbulence, which is based on the ideal MHD invariants are energy, cross helicity and magnetic helicity. However, for rotating MHD turbulence, the cross helicity is no longer an exact invariant, although rms cross helicity becomes quasistationary during an ideal MHD simulation. This and the anisotropy imposed by rotation suggests an ansatz in which an effective, nonzero value of cross helicity is assigned to axisymmetric modes and zero cross helicity to non-axisymmetric modes. This hybrid statistics predicts a large-scale quasistationary magnetic field due to broken ergodicity , as well as dipole vector alignment with the rotation axis, both of which are observed numerically. We find that only a relatively small value of effective cross helicity leads to the prediction of a dipole moment vector that is closely aligned (less than 10 degrees) with the rotation axis. We also discuss the effect of initial conditions, dissipation and grid size on the numerical simulations and statistical theory.
MHD Wave Modes Resolved in Fine-Scale Chromospheric Magnetic Structures
NASA Astrophysics Data System (ADS)
Verth, G.; Jess, D. B.
Due to its complex and dynamic fine-scale structure, the chromosphere is a particularly challenging region of the Sun's atmosphere to understand. It is now widely accepted that to model chromospheric dynamics, even on a magnetohydrodynamic (MHD) scale, while also calculating spectral line emission, one must realistically include the effects of partial ionization and radiative transfer in a multi-fluid plasma under non-LTE conditions. Accurate quantification of MHD wave energetics must be founded on a precise identification of the actual wave mode being observed. This chapter focuses on MHD kink-mode identification, MHD sausage mode identification, and MHD torsional Alfvén wave identification. It then reviews progress in determining more accurate energy flux estimations of specific MHD wave modes observed in the chromosphere. The chapter finally examines how the discovery of these MHD wave modes has helped us advance the field of chromospheric magnetoseismology.
S.S. Medley; N.N. Gorelenkov; R. Andre; R.E. Bell; D.S. Darrow; E.D. Fredrickson; S.M. Kaye; B.P. LeBlanc; A.L. Roquemore; and the NSTX Team
2004-03-15
MHD-induced energetic ion loss in neutral-beam-heated H-mode [high-confinement mode] discharges in NSTX [National Spherical Torus Experiment] is discussed. A rich variety of energetic ion behavior resulting from magnetohydrodynamic (MHD) activity is observed in the NSTX using a horizontally scanning Neutral Particle Analyzer (NPA) whose sightline views across the three co-injected neutral beams. For example, onset of an n = 2 mode leads to relatively slow decay of the energetic ion population (E {approx} 10-100 keV) and consequently the neutron yield. The effect of reconnection events, sawteeth, and bounce fishbones differs from that observed for low-n, low-frequency, tearing-type MHD modes. In this case, prompt loss of the energetic ion population occurs on a time scale of less than or equal to 1 ms and a precipitous drop in the neutron yield occurs. This paper focuses on MHD-induced ion loss during H-mode operation in NSTX. After H-mode onset, the NPA charge-exchange spectrum usually exhibits a significant loss of energetic ions only for E > E(sub)b/2 where E(sub)b is the beam injection energy. The magnitude of the energetic ion loss was observed to decrease with increasing tangency radius, R(sub)tan, of the NPA sightline, increasing toroidal field, B(sub)T, and increasing neutral-beam injection energy, E(sub)b. TRANSP modeling suggests that MHD-induced ion loss is enhanced during H-mode operation due to an evolution of the q and beam deposition profiles that feeds both passing and trapped ions into the region of low-n MHD activity. ORBIT code analysis of particle interaction with a model magnetic perturbation supported the energy selectivity of the MHD-induced loss observed in the NPA measurements. Transport analysis with the TRANSP code using a fast-ion diffusion tool to emulate the observed MHD-induced energetic ion loss showed significant modifications of the neutral- beam heating as well as the power balance, thermal diffusivities, energy confinement times, and toroidal beta. A proper accounting of energetic ion loss is therefore important for accurate analysis of power balance and transport in plasmas exhibiting MHD-induced energetic ion loss.
2D radiation-magnetohydrodynamic simulations of SATURN imploding Z-pinches
Hammer, J.H.; Eddleman, J.L.; Springer, P.T.
1995-11-06
Z-pinch implosions driven by the SATURN device at Sandia National Laboratory are modeled with a 2D radiation magnetohydrodynamic (MHD) code, showing strong growth of magneto-Rayleigh Taylor (MRT) instability. Modeling of the linear and nonlinear development of MRT modes predicts growth of bubble-spike structures that increase the time span of stagnation and the resulting x-ray pulse width. Radiation is important in the pinch dynamics keeping the sheath relatively cool during the run-in and releasing most of the stagnation energy. The calculations give x-ray pulse widths and magnitudes in reasonable agreement with experiments, but predict a radiating region that is too dense and radially localized at stagnation. We also consider peaked initial density profiles with constant imploding sheath velocity that should reduce MRT instability and improve performance. 2D krypton simulations show an output x-ray power > 80 TW for the peaked profile.
Experimental investigation of the magnetohydrodynamic parachute effect in a hypersonic air flow
NASA Astrophysics Data System (ADS)
Fomichev, V. P.; Yadrenkin, M. A.
2013-01-01
New data on experimental implementation of the magnetohydrodynamic (MHD) parachute configuration in an air flow with Mach number M = 6 about a flat plate are considered. It is shown that MHD interaction near a flat plate may transform an attached oblique shock wave into a normal detached one, which considerably extends the area of body-incoming flow interaction. This effect can be employed in optimizing return space vehicle deceleration conditions in the upper atmosphere.
NASA Astrophysics Data System (ADS)
Wu, S. T.; Zhou, Yufen; Jiang, Chaowei; Feng, Xueshang; Wu, Chin-Chun; Hu, Qiang
2016-02-01
In this study, we present a three-dimensional magnetohydrodynamic model based on an observed eruptive twisted flux rope (sigmoid) deduced from solar vector magnetograms. This model is a combination of our two very well tested MHD models: (i) data-driven 3-D magnetohydrodynamic (MHD) active region evolution (MHD-DARE) model for the reconstruction of the observed flux rope and (ii) 3-D MHD global coronal-heliosphere evolution (MHD-GCHE) model to track the propagation of the observed flux rope. The 6 September 2011, AR11283, event is used to test this model. First, the formation of the flux rope (sigmoid) from AR11283 is reproduced by the MHD-DARE model with input from the measured vector magnetograms given by Solar Dynamics Observatory/Helioseismic and Magnetic Imager. Second, these results are used as the initial boundary condition for our MHD-GCHE model for the initiation of a coronal mass ejection (CME) as observed. The model output indicates that the flux rope resulting from MHD-DARE produces the physical properties of a CME, and the morphology resembles the observations made by STEREO/COR-1.
Prospects for Nuclear Electric Propulsion Using Closed-Cycle Magnetohydrodynamic Energy Conversion
NASA Technical Reports Server (NTRS)
Litchford, R. J.; Bitteker, L. J.; Jones, J. E.
2001-01-01
Nuclear electric propulsion (NEP) has long been recognized as a major enabling technology for scientific and human exploration of the solar system, and it may conceivably form the basis of a cost-effective space transportation system suitable for space commerce. The chief technical obstacles to realizing this vision are the development of efficient, high-power (megawatt-class) electric thrusters and the development of low specific mass (less than 1 kg/kWe) power plants. Furthermore, comprehensive system analyses of multimegawatt class NEP systems are needed in order to critically assess mission capability and cost attributes. This Technical Publication addresses some of these concerns through a systematic examination of multimegawatt space power installations in which a gas-cooled nuclear reactor is used to drive a magnetohydrodynamic (MHD) generator in a closed-loop Brayton cycle. The primary motivation for considering MHD energy conversion is the ability to transfer energy out of a gas that is simply too hot for contact with any solid material. This has several intrinsic advantages including the ability to achieve high thermal efficiency and power density and the ability to reject heat at elevated temperatures. These attributes lead to a reduction in system specific mass below that obtainable with turbine-based systems, which have definite solid temperature limits for reliable operation. Here, the results of a thermodynamic cycle analysis are placed in context with a preliminary system analysis in order to converge on a design space that optimizes performance while remaining clearly within established bounds of engineering feasibility. MHD technology issues are discussed including the conceptual design of a nonequilibrium disk generator and opportunities for exploiting neutron-induced ionization mechanisms as a means of increasing electrical conductivity and enhancing performance and reliability. The results are then used to make a cursory examination of piloted Mars missions during the 2018 opportunity.
Solar-driven liquid metal magnetohydrodynamic generator
NASA Technical Reports Server (NTRS)
Lee, J. H.; Hohl, F.
1981-01-01
A solar oven heated by concentrated solar radiation as the heat source of a liquid metal magnetohydrodynamic (LMMHD) power generation system is proposed. The design allows the production of electric power in space, as well as on Earth, at high rates of efficiency. Two types of the solar oven suitable for the system are discussed.
Solar-driven liquid metal magnetohydrodynamic generator
Lee, J.H.; Hohl, F.
1981-05-01
A solar oven heated by concentrated solar radiation as the heat source of a liquid metal magnetohydrodynamic (LMMHD) power generation system is proposed. The design allows the production of electric power in space, as well as on Earth, at high rates of efficiency. Two types of the solar oven suitable for the system are discussed.
Possible uses for Phillips Laboratory MHD generator. Final report, 1 October 1994-30 August 1995
Turchi, P.J.
1995-08-01
There is interest in electromagnetic energy sources for applications to directed energy weapons. Candidates include portable conventional rotating machinery electric generators, magnetic flux compression generators (aka explosive generators, magnetocumulative generators or MCGs) based on explosive action, and magnetohydrodynamic (MHD) generators using chemical energy of explosives or rocket propellants. For portable high energy MHD generators, US technology base appeared to need rescue. The US has received a MHD device in the PAMlR-3U, developed in the former Soviet Union. The present discussion considers uses of this generator for programs on high-power microwave systems and other directed energy concepts. Future applications will be limited by development and funding of specific technical needs. A useful next step would be detailed design of a system to charge high-voltage pulsers. This design should include comparison of single-pulse switching to achieve high-voltage from an inductive storage coil (energy storage option) vs repetitive switching at low voltage, followed by custom built transformers (direct drive option).
Temporal and spatial turbulent spectra of MHD plasma and an observation of variance anisotropy
Schaffner, D. A.; Brown, M. R.; Lukin, V. S.
2014-08-01
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.
Temporal and Spatial Turbulent Spectra of MHD Plasma and an Observation of Variance Anisotropy
NASA Astrophysics Data System (ADS)
Schaffner, D. A.; Brown, M. R.; Lukin, V. S.
2014-08-01
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.
Magnetohydrodynamic simulations of global accretion disks with vertical magnetic fields
Suzuki, Takeru K.; Inutsuka, Shu-ichiro
2014-04-01
We report results of three-dimensional magnetohydrodynamical (MHD) simulations of global accretion disks threaded with weak vertical magnetic fields. We perform the simulations in the spherical coordinates with different temperature profiles and accordingly different rotation profiles. In the cases with a spatially constant temperature, because the rotation frequency is vertically constant in the equilibrium condition, general properties of the turbulence excited by magnetorotational instability are quantitatively similar to those obtained in local shearing box simulations. On the other hand, in the cases with a radially variable temperature profile, the vertical differential rotation, which is inevitable in the equilibrium condition, winds up the magnetic field lines in addition to the usual radial differential rotation. As a result, the coherent wound magnetic fields contribute to the Maxwell stress in the surface regions. We obtain nondimensional density and velocity fluctuations ∼0.1-0.2 at the midplane. The azimuthal power spectra of the magnetic fields show shallower slopes, ∼m {sup 0} – m {sup –1}, than those of velocity and density. The Poynting flux associated with the MHD turbulence drives intermittent and structured disk winds as well as sound-like waves toward the midplane. The mass accretion mainly occurs near the surfaces, and the gas near the midplane slowly moves outward in the time domain of the present simulations. The vertical magnetic fields are also dragged inward in the surface regions, while they stochastically move outward and inward around the midplane. We also discuss an observational implication of induced spiral structure in the simulated turbulent disks.
NASA Technical Reports Server (NTRS)
Smith, M.; Nichols, L. D.; Seikel, G. R.
1974-01-01
Performance and power costs of H2-O2 combustion powered steam-MHD central power systems are estimated. Hydrogen gas is assumed to be transmitted by pipe from a remote coal gasifier into the city and converted to electricity in a steam MHD plant having an integral gaseous oxygen plant. These steam MHD systems appear to offer an attractive alternative to both in-city clean fueled conventional steam power plants and to remote coal fired power plants with underground electric transmission into the city. Status and plans are outlined for an experimental evaluation of H2-O2 combustion-driven MHD power generators at NASA Lewis Research Center.
MHD Turbulence and Magnetic Dynamos
NASA Technical Reports Server (NTRS)
Shebalin, John V
2014-01-01
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.
Magnetohydrodynamic cellular automata
NASA Technical Reports Server (NTRS)
Montgomery, David; Doolen, Gary D.
1987-01-01
A generalization of the hexagonal lattice gas model of Frisch, Hasslacher and Pomeau is shown to lead to two-dimensional magnetohydrodynamics. The method relies on the ideal point-wise conservation law for vector potential.
Global invariants in ideal magnetohydrodynamic turbulence
Shebalin, John V.
2013-10-15
Magnetohydrodynamic (MHD) turbulence is an important though incompletely understood factor affecting the dynamics of many astrophysical, geophysical, and technological plasmas. As an approximation, viscosity and resistivity may be ignored, and ideal MHD turbulence may be investigated by statistical methods. Incompressibility is also assumed and finite Fourier series are used to represent the turbulent velocity and magnetic field. The resulting model dynamical system consists of a set of independent Fourier coefficients that form a canonical ensemble described by a Gaussian probability density function (PDF). This PDF is similar in form to that of Boltzmann, except that its argument may contain not just the energy multiplied by an inverse temperature, but also two other invariant integrals, the cross helicity and magnetic helicity, each multiplied by its own inverse temperature. However, the cross and magnetic helicities, as usually defined, are not invariant in the presence of overall rotation or a mean magnetic field, respectively. Although the generalized form of the magnetic helicity is known, a generalized cross helicity may also be found, by adding terms that are linear in the mean magnetic field and angular rotation vectors, respectively. These general forms are invariant even in the presence of overall rotation and a mean magnetic field. We derive these general forms, explore their properties, examine how they extend the statistical theory of ideal MHD turbulence, and discuss how our results may be affected by dissipation and forcing.
Energetic particle effects on global magnetohydrodynamic modes
NASA Astrophysics Data System (ADS)
Cheng, C. Z.
1990-06-01
The effects of energetic particles on magnetohydrodynamic (MHD) type modes are studied using analytical theories and the nonvariational kinetic-MHD stability code (nova-k) [Workshop on Theory of Fusion Plasmas, (Societa Italiana di Fisica, Bologna, 1987), p. 185]. In particular, the problems of (1) the stabilization of ideal MHD internal kink modes and the excitation of resonant ``fishbone'' internal modes and (2) the alpha particle destabilization of toroidicity-induced Alfvn eigenmodes (TAE) via transit resonances are addressed. Analytical theories are presented to help explain the nova-k results. For energetic trapped particles generated by neutral beam injection or ion cyclotron resonant heating, a stability window for the n=1 internal kink mode in the hot particle beta space exists even in the absence of core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to resonantly excite instability of the n=1 internal mode and can lower the critical beta threshold. The circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha-particle pressure.
Imbalanced relativistic force-free magnetohydrodynamic turbulence
Cho, Jungyeon; Lazarian, A.
2014-01-01
When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfvénic MHD turbulence in the relativistic limit can be described by interactions of counter-traveling wave packets. In this paper, we numerically study strong imbalanced MHD turbulence in such environments. Here, imbalanced turbulence means the waves traveling in one direction (dominant waves) have higher amplitudes than the opposite-traveling waves (sub-dominant waves). We find that (1) spectrum of the dominant waves is steeper than that of sub-dominant waves, (2) the anisotropy of the dominant waves is weaker than that of sub-dominant waves, and (3) the dependence of the ratio of magnetic energy densities of dominant and sub-dominant waves on the ratio of energy injection rates is steeper than quadratic (i.e., b{sub +}{sup 2}/b{sub −}{sup 2}∝(ϵ{sub +}/ϵ{sub −}){sup n} with n > 2). These results are consistent with those obtained for imbalanced non-relativistic Alfvénic turbulence. This corresponds well to the earlier reported similarity of the relativistic and non-relativistic balanced magnetic turbulence.
Nonlinear magnetohydrodynamic stability
Bauer, F.; Betancourt, O.; Garabedian, P.
1981-01-01
Ways have been found to significantly upgrade the resolution of an equilibrium and stability code that is based on the variational principle of ideal magnetohydrodynamics. Nonlinear saturation of ballooning modes for tokamaks has been demonstrated using a revised version of the code. Second stability regions are calculated from the nonlinear dependence of deltaW on ..beta... An l=2,3 torsatron is described that appears to have no ideal magnetohydrodynamic instabilities for ..beta.. as high as 5%.
Transition from Kinetic to MHD Behavior in a Collisionless Plasma
NASA Astrophysics Data System (ADS)
Parashar, Tulasi N.; Matthaeus, William H.; Shay, Michael A.; Wan, Minping
2015-10-01
The study of kinetic effects in heliospheric plasmas requires representation of dynamics at sub-proton scales, but in most cases the system is driven by magnetohydrodynamic (MHD) activity at larger scales. The latter requirement challenges available computational resources, which raises the question of how large such a system must be to exhibit MHD traits at large scales while kinetic behavior is accurately represented at small scales. Here we study this implied transition from kinetic to MHD-like behavior using particle-in-cell (PIC) simulations, initialized using an Orszag-Tang Vortex. The PIC code treats protons, as well as electrons, kinetically, and we address the question of interest by examining several different indicators of MHD-like behavior.
Three Dimensional Simulations of Compressible Hall MHD Plasmas
Shaikh, Dastgeer; Shukla, P. K.
2008-10-15
We have developed three dimensional, time dependent, compressible, non-adiabatic, driven and massively parallelized Hall magnetohydrodynamic (MHD) simulations to investigate turbulent spectral cascades in a regime where characteristic lengthscales associated with plasma fluctuations are smaller than ion gyro radii. Such regime is ubiquitously present in solar wind and many other collisionless space plasmas. Particularly in the solar wind, the high time resolution databases identify a spectral break at the end of MHD inertial range spectrum that corresponds to a high frequency regime. In the regime, turbulent cascades cannot be explained by the usual MHD models. With the help of our 3D Hall MHD code, we find that characteristic turbulent interactions in the high frequency regime evolve typically on kinetic Alfven time scales. The turbulent fluctuation associated with kinetic Alfven interactions are compressive and anisotropic and possess equipartition of kinetic and magnetic energies.
MHD turbulence in the intracluster medium
NASA Astrophysics Data System (ADS)
Falceta-Gonalves, Diego; Kowal, G.; de Gouveia Dal Pino, E.; Santos-Lima, R.; Nakwacki, S.; Lazarian, A.
2015-03-01
In this work we discuss the turbulent evolution of structures in the intracluster medium based on the two fluid approximations: MHD and collisionless plasma under Chew Goldberger Low (CGL) closure. Turbulence excited by galactic motions and gas inflow in intracluster medium will develop in very different ways considering the two fluid approaches. Statistics of density distributions, and velocity and magnetic fields are provided. Compared to the standard MHD case, the instabilities that arise from CGL-MHD models strongly modify the probability distribution functions of the plasma velocity and density, basically increasing their dispersion. Moreover, the spectra of both density and velocity show increased power at small scales, due to the instabilities growth rate that are larger as smaller scales. Finally, in high beta plasmas, i.e. B 2 << P, a fast increase of the magnetic energy density is observed in the CGL-MHD models, faster than the standard MHD turbulent dynamo that operates at timescales ? ~ L/v L . The signatures of the increased power at small scales and the increase of magnetic field intensity from CGL-MHD models could be observed at radio wavelengths. A comparison of the structure function of the synchrotron emission, as well as the statistics of Faraday rotation effects on the synchrotron polarization, for both the MHD and CGL-MHD models is provided.
Small-scale behavior of Hall magnetohydrodynamic turbulence
NASA Astrophysics Data System (ADS)
Stawarz, Julia E.; Pouquet, Annick
2015-12-01
Decaying Hall magnetohydrodynamic (HMHD) turbulence is studied using three-dimensional (3D) direct numerical simulations with grids up to 7683 points and two different types of initial conditions. Results are compared to analogous magnetohydrodynamic (MHD) runs and both Laplacian and Laplacian-squared dissipative operators are examined. At scales below the ion inertial length, the ratio of magnetic to kinetic energy as a function of wave number transitions to a magnetically dominated state. The transition in behavior is associated with the advection term in the momentum equation becoming subdominant to dissipation. Examination of autocorrelation functions reveals that, while current and vorticity structures are similarly sized in MHD, HMHD current structures are narrower and vorticity structures are wider. The electric field autocorrelation function is significantly narrower in HMHD than in MHD and is similar to the HMHD current autocorrelation function at small separations. HMHD current structures are found to be significantly more intense than in MHD and appear to have an enhanced association with strong alignment between the current and magnetic field, which may be important in collisionless plasmas where field-aligned currents can be unstable. When hyperdiffusivity is used, a longer region consistent with a k-7 /3 scaling is present for right-polarized fluctuations when compared to Laplacian dissipation runs.
Attig, R.C.
1996-10-09
The development of coal-fired magnetohydrodynamic (MHD) power can be viewed as consisting of two parts; the topping cycle and the bottoming cycle. The topping cycle consists of the coal combustor, MHD generator and associated components. The bottoming cycle consists of the heat recovery, steam generation, seed recovery/regeneration, emissions control (gas and particulate), ash handling and deposition, and materials evaluation. The report concentrates on the bottoming cycle, for which much of the technology was developed at the University of Tennessee Space Institute (UTSI). Because of the complexity of the required technology, a number of issues required investigation. Of specific concern regarding the bottoming cycle, was the design of the steam cycle components and emissions control. First, the high combustion temperatures and the use of large quantities of potassium in the MHD combustor results in a difference in the composition of the gases entering the bottoming cycle compared to conventional systems. Secondly, a major goal of the UTSI effort was to use a variety of coals in the MHD system, especially the large reserves of high-sulfur coals available in the United States.
Broken Ergodicity in Two-Dimensional Homogeneous Magnetohydrodynamic Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2010-01-01
Two-dimensional (2-D) homogeneous magnetohydrodynamic (MHD) turbulence has many of the same qualitative features as three-dimensional (3-D) homogeneous MHD turbulence.The se features include several ideal invariants, along with the phenomenon of broken ergodicity. Broken ergodicity appears when certain modes act like random variables with mean values that are large compared to their standard deviations, indicating a coherent structure or dynamo.Recently, the origin of broken ergodicity in 3-D MHD turbulence that is manifest in the lowest wavenumbers was explained. Here, a detailed description of the origins of broken ergodicity in 2-D MHD turbulence is presented. It will be seen that broken ergodicity in ideal 2-D MHD turbulence can be manifest in the lowest wavenumbers of a finite numerical model for certain initial conditions or in the highest wavenumbers for another set of initial conditions.T he origins of broken ergodicity in ideal 2-D homogeneous MHD turbulence are found through an eigen analysis of the covariance matrices of the modal probability density functions.It will also be shown that when the lowest wavenumber magnetic field becomes quasi-stationary, the higher wavenumber modes can propagate as Alfven waves on these almost static large-scale magnetic structures
Feasibility of MHD submarine propulsion
Doss, E.D. ); Sikes, W.C. )
1992-09-01
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.
MHD Integrated Topping Cycle Project
Not Available
1992-01-01
The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois {number sign}6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.
Compressibility and rotation effects on transport suppression in magnetohydrodynamic turbulence
Yoshizawa, A.
1996-03-01
Compressibility and rotation effects on turbulent transports in magnetohydrodynamic (MHD) flows under arbitrary mean field are investigated using a Markovianized two-scale statistical approach. Some new aspects of MHD turbulence are pointed out in close relation to plasma compressibility. Special attention is paid to the turbulent electromotive force, which plays a central role in the generation of magnetic and velocity fluctuations. In addition to plasma rotation, the interaction between compressibility and magnetic fields is shown to bring a few factors suppressing MHD fluctuations and, eventually, density and temperature transports, even in the presence of steep mean density and temperature gradients. This finding is discussed in the context of the turbulence-suppression mechanism in the tokamak{close_quote}s high-confinement modes. {copyright} {ital 1996 American Institute of Physics.}
NASA Astrophysics Data System (ADS)
Maget, P.; Huysmans, G. T. A.; Ltjens, H.; Ottaviani, M.; Moreau, Ph; Sgui, J.-L.
2009-06-01
Attempts to run non-inductive plasma discharges on Tore Supra sometimes fail due to the triggering of magneto-hydro-dynamic (MHD) instabilities that saturate at a large amplitude, producing degraded confinement and loss of wave driven fast electrons (the so-called MHD regime (Maget et al 2005 Nucl. Fusion 45 69-80)). In this paper we investigate the transition to this soft (in the sense of non-disruptive) MHD limit from experimental observations, and compare it with non-linear code predictions. Such a comparison suggests that different non-linear regimes, with periodic relaxations or saturation, are correctly understood. However, successful non-inductive discharges without detectable magnetic island at q = 2 cannot be reproduced if realistic transport coefficients are used in the computation. Additional physics seems mandatory for explaining these discharges, such as diamagnetic effects, that could also justify cases of abrupt transition to the MHD regime.
Energy dissipation in magnetohydrodynamic turbulence: coherent structures or 'nanoflares'?
Zhdankin, Vladimir; Boldyrev, Stanislav; Perez, Jean Carlos; Tobias, Steven M.
2014-11-10
We investigate the intermittency of energy dissipation in magnetohydrodynamic (MHD) turbulence by identifying dissipative structures and measuring their characteristic scales. We find that the probability distribution of energy dissipation rates exhibits a power-law tail with an index very close to the critical value of 2.0, which indicates that structures of all intensities contribute equally to energy dissipation. We find that energy dissipation is uniformly spread among coherent structures with lengths and widths in the inertial range. At the same time, these structures have thicknesses deep within the dissipative regime. As the Reynolds number is increased, structures become thinner and more numerous, while the energy dissipation continues to occur mainly in large-scale coherent structures. This implies that in the limit of high Reynolds number, energy dissipation occurs in thin, tightly packed current sheets which nevertheless span a continuum of scales up to the system size, exhibiting features of both coherent structures and nanoflares previously conjectured as a coronal heating mechanism.
Zonal flow driven by energetic particle during magneto-hydro-dynamic burst in a toroidal plasma
NASA Astrophysics Data System (ADS)
Ohshima, S.; Fujisawa, A.; Shimizu, A.; Nakano, H.; Iguchi, H.; Yoshimura, Y.; Nagaoka, K.; Minami, T.; Isobe, M.; Nishimura, S.; Suzuki, C.; Akiyama, T.; Takahashi, C.; Takeuchi, M.; Ito, T.; Watari, T.; Kumazawa, R.; Itoh, S.-I.; Itoh, K.; Matsuoka, K.; Okamura, S.
2007-11-01
The internal structural measurements of electric field and density using twin heavy ion beam probes have been performed to elucidate the nonlinear evolution of the magneto-hydro-dynamic (MHD) bursty phenomenon driven by the interaction with high-energy particles in a toroidal plasma. The results have given the finest observation of the internal structure of plasma quantities, such as electric field, density and magnetic field distortion, which nonlinearly develop during the MHD phenomenon. In particular, the finding of a new kind of oscillating zonal flow driven by interaction between energetic particles and MHD modes should be emphasized for burning state plasmas.
NASA Technical Reports Server (NTRS)
Barth, Timothy
2005-01-01
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.
MHD shocks in coronal mass ejections
NASA Technical Reports Server (NTRS)
Steinolfson, R. S.
1991-01-01
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).
Numerical MHD codes for modeling astrophysical flows
NASA Astrophysics Data System (ADS)
Koldoba, A. V.; Ustyugova, G. V.; Lii, P. S.; Comins, M. L.; Dyda, S.; Romanova, M. M.; Lovelace, R. V. E.
2016-05-01
We describe a Godunov-type magnetohydrodynamic (MHD) code based on the Miyoshi and Kusano (2005) solver which can be used to solve various astrophysical hydrodynamic and MHD problems. The energy equation is in the form of entropy conservation. The code has been implemented on several different coordinate systems: 2.5D axisymmetric cylindrical coordinates, 2D Cartesian coordinates, 2D plane polar coordinates, and fully 3D cylindrical coordinates. Viscosity and diffusivity are implemented in the code to control the accretion rate in the disk and the rate of penetration of the disk matter through the magnetic field lines. The code has been utilized for the numerical investigations of a number of different astrophysical problems, several examples of which are shown.
NASA Astrophysics Data System (ADS)
Ofman, L.
This chapter focuses on reviewing several observational aspects of magnetohydrodynamic (MHD) waves in the solar wind, in particular on Alfvén waves, Alfvénic turbulent spectrum, and their role in heating and accelerating the solar wind. It also reviews computational models that incorporate Alfvén waves as the driving source of the wind in the lower corona (coronal holes) and in the inner heliosphere, with emphasis on multi-dimensional models. Evidence for MHD waves in the solar wind is obtained from interplanetary scintillation (IPS) observations using Earth-based radio telescope observations of distant (galactic) radio sources. The solar wind electron density variability in the line of sight affects the received radio signal. The propagating fluctuations and their correlations are used to estimate the solar wind velocity and the wave amplitude in the parallel and the perpendicular directions in line of sight.
MHD Equilibria and Triggers for Prominence Eruption
NASA Astrophysics Data System (ADS)
Fan, Yuhong
Magneto-hydrodynamic (MHD) simulations of the emergence of twisted magnetic flux tubes from the solar interior into the corona are discussed to illustrate how twisted and sheared coronal magnetic structures (with free magnetic energy), capable of driving filament eruptions, can form in the corona in emerging active regions. Several basic mechanisms that can disrupt the quasi-equilibrium coronal structures and trigger the release of the stored free magnetic energy are discussed. These include both ideal processes such as the onset of the helical kink instability and the torus instability of a twisted coronal flux rope structure and the non-ideal process of the onset of fast magnetic reconnections in current sheets. Representative MHD simulations of the non-linear evolution involving these mechanisms are presented.
Barnes, P.R.; Vance, E.F.
1992-03-01
A nuclear detonation at altitudes several hundred kilometers above the earth will severely distort the earth`s magnetic field and result in a strong magnetohyrodynamic electromagnetic pulse (MHD-EMP). The geomagnetic disturbance interacts with the soil to induce current and horizontal electric gradients. The geomagnetic disturbance interacts with the soil to induced current and horizontal electric gradients in the earth. MHD-EMP, also called E3 since it is the third component of the high-altitude EMP (HEMP), lasts over 100 s after the exoatmospheric burst. MHD-EMP is similar to solar geomagnetic storms in it`s global and low frequency (less than 1 Hz) nature except that E3 can be much more intense with a far shorter duration. When the MHD-EMP gradients are integrated over great distances by power lines, communication cables, or other long conductors, the induced voltages are significant. (The horizontal gradients in the soil are too small to induce major responses by local interactions with facilities.) The long pulse waveform for MHD-EMP-induced currents on long lines has a peak current of 200 A and a time-to-half-peak of 100 s. If this current flows through transformer windings, it can saturate the magnetic circuit and cause 60 Hz harmonic production. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building and the commercial power harmonics and voltage swings must be addressed. The transfer switch would be expected to respond to the voltage fluctuations as long as the harmonics have not interfered with the switch control circuitry. The major sources of MHD-EMP induced currents are the commercial power lines and neutral; neutral current indirect coupling to the facility power or ground system via the metal fence, powered gate, parking lights, etc; metal water pipes; phone lines; and other long conductors that enter or come near the facility. The major source of harmonics is the commercial power system.
Performance of Combustion Disk MHD Generators.
NASA Astrophysics Data System (ADS)
Jenkins, Marion Karl
Results of an experimental and analytical study of radial flow disk magnetohydrodynamic generators are presented. The overall goal of the study was to investigate disk generators for application to baseload power generation. The experimental work consisted of a series of combustion-driven steady state experiments with a hot-wall channel operated in a superconducting magnet. Channel operating characteristics were examined under a variety of plasma temperatures, velocities, and magnetic field strengths. The channel was operated continuously in tests lasting several hours, with plasma temperatures ranging up to 2800(DEGREES)K and magnetic fields up to 5.5 Tesla. Voltage -current characteristics showed the expected linear behavior, and the expected dependence on channel operating conditions such as magnetic field strength and velocity was observed. Plasma conditions were inferred from the electrical conductivity, which was measured parallel to the applied magnetic field in the channel inlet nozzle. Steady voltage and current distributions on the segmented ring cathode were fairly uniform, with the largest deviations occurring as expected near open and short circuit conditions. Statistical analysis of fluctuating voltage signals showed strong positive correlations between probes mounted at different locations within the channel, indicating the absence of spoke-type plasma nonuniformities that have been observed in shock tube-driven disk experiments. Measured values of voltages and currents were less than expected, indicating the presence of substantial loss mechanisms in the channel. These losses were postulated to be caused by insulator wall current leakage and electrode voltage drop. Radial voltage profiles and open circuit voltage measurements verified the presence of these effects. An ideal homogeneous plasma model was developed to account for the losses, and values obtained for the loss terms are in agreement with relevant linear generator results. Limiting values of Hall fields were investigated using external voltage augmentation, and electric fields of 9 KV/m were observed in the channel with no evidence of breakdown. The analytical work consisted of the development of a two-dimensional computer program to predict boundary layer phenomena in disk generators, including the effects of turbulence, variable gas properties and MHD interaction. The numerical results show the effect of the variable MHD body force across the insulating wall boundary layer, giving rise to boundary layer velocities higher than those in the core. This leads to greater skin friction and heat transfer losses than what would be predicted with a quasi -one dimensional model. Calculations carried out for baseload -sized generators show the expected dependence of boundary layer behavior on channel operating conditions such as wall temperature, swirl, magnetic field strength and channel loading.
VisAn MHD: a toolbox in Matlab for MHD computer model data visualisation and analysis
NASA Astrophysics Data System (ADS)
Daum, P.
2007-03-01
Among the many challenges facing modern space physics today is the need for a visualisation and analysis package which can examine the results from the diversity of numerical and empirical computer models as well as observational data. Magnetohydrodynamic (MHD) models represent the latest numerical models of the complex Earth's space environment and have the unique ability to span the enormous distances present in the magnetosphere from several hundred kilometres to several thousand kilometres above the Earth surface. This feature enables scientist to study complex structures of processes where otherwise only point measurements from satellites or ground-based instruments are available. Only by combining these observational data and the MHD simulations it is possible to enlarge the scope of the point-to-point observations and to fill the gaps left by measurements in order to get a full 3-D representation of the processes in our geospace environment. In this paper we introduce the VisAn MHD toolbox for Matlab as a tool for the visualisation and analysis of observational data and MHD simulations. We have created an easy to use tool which is capable of highly sophisticated visualisations and data analysis of the results from a diverse set of MHD models in combination with in situ measurements from satellites and ground-based instruments. The toolbox is being released under an open-source licensing agreement to facilitate and encourage community use and contribution.
Dissipative effects on finite-Larmor-radius modified magnetohydrodynamic ballooning modes
Connor, J.W.; Chen, L.; Chance, M.S.
1982-11-01
Finite-ion-Larmor-radius (FLR) effects provide a band of additional stability for values of ..beta..(exactly equal to plasma pressure/magnetic pressure) exceeding the limit predicted for ideal magnetohydrodynamic (MHD) ballooning modes. We examine the effect of particle collisions on the stable modes of the FLR modified ideal theory that exist in this range of ..beta.. values.
Plasma flow structures as analytical solution of a magneto-hydro-dynamic model with pressure
NASA Astrophysics Data System (ADS)
Paccagnella, R.
2012-03-01
In this work starting from a set of magnetohydrodynamic (MHD) equations that describe the dynamical evolution for the pressure driven resistive/interchange modes in a magnetic confinement system, global solutions for the plasma flow relevant for toroidal pinches like tokamaks and reversed field pinches (RFPs) are derived. Analytical solutions for the flow stream function associated with the dominant modes are presented.
The superconducting MHD-propelled ship YAMATO-1
NASA Astrophysics Data System (ADS)
Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro
1995-04-01
In 1985 the Ship & Ocean Foundation (SOF) created a committee under the chairmanship of Mr. Yohei Sasakawa, Former President of the Ship & Ocean Foundation, and began researches into superconducting magnetohydrodynamic (MHD) ship propulsion. In 1989 SOF set to construction of a experimental ship on the basis of theoretical and experimental researches pursued until then. The experimental ship named YAMATO-1 became the world's first superconducting MHD-propelled ship on her trial runs in June 1992. This paper describes the outline of the YAMATO-1 and sea trial test results.
The superconducting MHD-propelled ship YAMATO-1
NASA Technical Reports Server (NTRS)
Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro
1995-01-01
In 1985 the Ship & Ocean Foundation (SOF) created a committee under the chairmanship of Mr. Yohei Sasakawa, Former President of the Ship & Ocean Foundation, and began researches into superconducting magnetohydrodynamic (MHD) ship propulsion. In 1989 SOF set to construction of a experimental ship on the basis of theoretical and experimental researches pursued until then. The experimental ship named YAMATO-1 became the world's first superconducting MHD-propelled ship on her trial runs in June 1992. This paper describes the outline of the YAMATO-1 and sea trial test results.
NASA Astrophysics Data System (ADS)
Tomida, Kengo; Okuzumi, Satoshi; Machida, Masahiro N.
2015-03-01
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.
Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Xu, Kun
1998-01-01
A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.
NASA Astrophysics Data System (ADS)
Guo, Xiaocheng
2015-06-01
By revisiting the derivation of the previously developed HLLC Riemann solver for magneto-hydrodynamics (MHD), the paper presents an extended HLLC Riemann solver specifically designed for the MHD system in which the magnetic field can be decomposed into a strong internal magnetic field and an external component. The derived HLLC Riemann solver satisfies the conservation laws. The numerical tests show that the extended solver deals with the global MHD simulation of the Earth's magnetosphere well, and maintains high numerical resolution. It recovers the previously developed HLLC Riemann solver for the MHD as long as the internal field is set to zero. Thus, it is backward compatible with the previous HLLC solver, and suitable for the MHD simulations no matter whether a strong internal magnetic field is included or not.
NASA Technical Reports Server (NTRS)
Fennelly, A. J.; Evans, C. R.
1980-01-01
Magnetohydrodynamic (MHD) perturbations in flat Robertson-Walker universes were analyzed, emphasizing their effects on galaxy formation. The Newtonian approximation is used. There is no increase in the growth rates beyond those of the usual perturbed Robertson-Walker models; the MHD modes extract as much energy as they contribute. Some global properties of fully MHD Bianchi I relativistic models are analyzed including vorticity, fluid accelerations, and dissipative effects. The time dependence of perturbations of a fully MHD diagonal Bianchi I cosmology is studied, with an enhanced growth rate of the density contrast of t found which is still not exponential Jeans-type growth. This indicates that a more detailed analysis is needed if a solution to the galaxy formation problem in MHD cosmologies is to be found.
Sub-Alfvenic Non-Ideal MHD Turbulence Simulations with Ambipolar Diffusion: I. Turbulence Statistics
Klein, R I; Li, P S; McKee, C F; Fisher, R
2008-04-10
Most numerical investigations on the role of magnetic fields in turbulent molecular clouds (MCs) are based on ideal magneto-hydrodynamics (MHD). However, MCs are weakly ionized, so that the time scale required for the magnetic field to diffuse through the neutral component of the plasma by ambipolar diffusion (AD) can be comparable to the dynamical time scale. We have performed a series of 256{sup 3} and 512{sup 3} simulations on supersonic but sub-Alfvenic turbulent systems with AD using the Heavy-Ion Approximation developed in Li et al. (2006). Our calculations are based on the assumption that the number of ions is conserved, but we show that these results approximately apply to the case of time-dependent ionization in molecular clouds as well. Convergence studies allow us to determine the optimal value of the ionization mass fraction when using the heavy-ion approximation for low Mach number, sub-Alfvenic turbulent systems. We find that ambipolar diffusion steepens the velocity and magnetic power spectra compared to the ideal MHD case. Changes in the density PDF, total magnetic energy, and ionization fraction are determined as a function of the AD Reynolds number. The power spectra for the neutral gas properties of a strongly magnetized medium with a low AD Reynolds number are similar to those for a weakly magnetized medium; in particular, the power spectrum of the neutral velocity is close to that for Burgers turbulence.
The generation and damping of propagating MHD kink waves in the solar atmosphere
Morton, R. J.; Verth, G.; Erdélyi, R.; Hillier, A. E-mail: g.verth@sheffield.ac.uk
2014-03-20
The source of the non-thermal energy required for the heating of the upper solar atmosphere to temperatures in excess of a million degrees and the acceleration of the solar wind to hundreds of kilometers per second is still unclear. One such mechanism for providing the required energy flux is incompressible torsional Alfvén and kink magnetohydrodynamic (MHD) waves, which are magnetically dominated waves supported by the Sun's pervasive and complex magnetic field. In particular, propagating MHD kink waves have recently been observed to be ubiquitous throughout the solar atmosphere, but, until now, critical details of the transport of the kink wave energy throughout the Sun's atmosphere were lacking. Here, the ubiquity of the waves is exploited for statistical studies in the highly dynamic solar chromosphere. This large-scale investigation allows for the determination of the chromospheric kink wave velocity power spectra, a missing link necessary for determining the energy transport between the photosphere and corona. Crucially, the power spectra contain evidence for horizontal photospheric motions being an important mechanism for kink wave generation in the quiescent Sun. In addition, a comparison with measured coronal power spectra is provided for the first time, revealing frequency-dependent transmission profiles, suggesting that there is enhanced damping of kink waves in the lower corona.
NASA Astrophysics Data System (ADS)
Sozzi, C.; Galperti, C.; Alessi, E.; Nowak, S.; Apruzzese, G.; Belli, F.; Bin, W.; Boncagni, L.; Botrugno, A.; Bruschi, A.; Buratti, P.; Calabrò, G.; Esposito, B.; Figini, L.; Garavaglia, S.; Granucci, G.; Grosso, L. A.; Marchetto, C.; Marinucci, M.; Marocco, D.; Mazzotta, C.; Mellera, V.; Minelli, D.; Mosconi, M.; Moro, A.; Piergotti, V.; Pucella, G.; Ramogida, G.; Romano, A.; Tudisco, O.
2015-08-01
Experiments on real time control of magneto-hydrodynamic (MHD) instabilities using injection of electron cyclotron waves (ECW) are being performed with a control system based on only three real time key items: an equilibrium estimator based on a statistical regression, a MHD instability marker (SVDH) using a three-dimensional array of pick-up coils and a fast ECW launcher able to poloidally steer the EC absorption volume with dρ/dt = 0.1/30 ms maximum radial speed. The MHD instability, usually a tearing mode with poloidal mode number m and toroidal mode number n such that m/n = 2/1 or 3/2 is deliberately induced either by neon gas injection or by a density ramp hitting the density limit. No diagnostics providing the radial localization of the instabilities have been used. The sensitivity of the used MHD marker allows to close the control loop solely on the effect of the actuator’s action with little elaboration. The nature of the instability triggering mechanism in these plasma prevents that the stabilization lasts longer than the ECW pulse. However when the ECW power is switched on, the instability amplitude shows a marked sensitivity to the position of the absorption volume with an increase or decrease of its growth rate. Moreover the suppression of the dominant mode by ECRH performed at high plasma density even at relatively low power level facilitates the development of a secondary mode. This minimized set of control tools aim to explore some of the difficulties which can be expected in a fusion reactor where reduced diagnostic capabilities and reduced actuator flexibility can be expected.
Globus, Noemie; Levinson, Amir
2014-11-20
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.
Observation of MHD Instabilities Driven by Energetic Electrons in the Large Helical Device
NASA Astrophysics Data System (ADS)
Mitsutaka, Isobe; Kunihiro, Ogawa; Akihiro, Shimizu; Masaki, Osakabe; Shin, Kubo; Toi, K.; LHD Experiment Group
2015-04-01
Coherent magnetic fluctuations in an acoustic range of frequency have been regularly observed in low-density (ne < 0.21019 m-3) plasmas with strong second harmonic electron cyclotron resonance heating (ECRH) on the Large Helical Device. Hard X-ray measurements indicated that energetic electrons are generated in these ECRH discharges. The magnetic fluctuations are suppressed in higher density discharges where energetic electrons are not present. The ECRH power modulation experiment indicated that the observed magnetohydrodynamic (MHD) mode has an acoustic nature rather than an Alfvnic nature. supported by the Grant-in-Aid for Encouragement of Scientists from the Japan Society for the Promotion of Science (No. 20656150). This work was also partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics (NSFC: No. 11261140328 and NRF: No. 2012K2A2A6000443)
A note on convective heat transfer of an MHD Jeffrey fluid over a stretching sheet
NASA Astrophysics Data System (ADS)
Ahmed, Jawad; Shahzad, Azeem; Khan, Masood; Ali, Ramzan
2015-11-01
This article focuses on the exact solution regarding convective heat transfer of a magnetohydrodynamic (MHD) Jeffrey fluid over a stretching sheet. The effects of joule and viscous dissipation, internal heat source/sink and thermal radiation on the heat transfer characteristics are taken in account in the presence of a transverse magnetic field for two types of boundary heating process namely prescribed power law surface temperature (PST) and prescribed heat flux (PHF). Similarity transformations are used to reduce the governing non-linear momentum and thermal boundary layer equations into a set of ordinary differential equations. The exact solutions of the reduced ordinary differential equations are developed in the form of confluent hypergeometric function. The influence of the pertinent parameters on the temperature profile is examined. In addition the results for the wall temperature gradient are also discussed in detail.
Ultra-High-Resolution Observations of MHD Waves in Photospheric Magnetic Structures
NASA Astrophysics Data System (ADS)
Jess, D. B.; Verth, G.
This chapter reviews the recent observations of waves and oscillations manifesting in fine-scale magnetic structures in the solar photosphere, which are often interpreted as the "building blocks' of the magnetic Sun. The authors found, through phase relationships between the various waveforms, that small-scale magnetic bright points (MBPs) in the photosphere demonstrated signatures of specific magnetoacoustic waves, in particular the sausage and kink modes. Modern magnetohydrodynamic (MHD) simulations of the lower solar atmosphere clearly show how torsional motions can easily be induced in magnetic elements in the photosphere through the processes of vortical motions and/or buffeting by neighboring granules. The authors detected significant power associated with high-frequency horizontal motions, and suggested that these cases may be especially important in the creation of a turbulent environment that efficiently promotes Alfvén wave dissipation.
MHD simulation of the planetary magnetospheres by using various scalar type supercomputer systems
NASA Astrophysics Data System (ADS)
Fukazawa, Keiichiro; Umeda, Takayuki; Ogino, Tatsuki; Walker, Raymond; Yumoto, Kiyohumi
Currently more than 85% of the "top 500" supercomputer systems in the world have adopted the "64-bit x86" processor architecture. However it is often mentioned that the performance of electromagnetic fluid codes is not as good on the scalar type computers (often less than 10% of peak performance efficiency) as compared to vector type computers. For instance our planetary magnetospheric magnetohydrodynamic code reached over 50% of performance efficiency on vector supercomputers. In this study we have carried out performance tuning and other measurements on massively parallel supercomputer systems with various types of scalar processors. We use the T2K open supercomputer at University of Tokyo (AMD Opteron processors), SR16000 at Kyushu University (IBM POWER6 processors), and FX1 (Fujitsu SPARC64VI processors) and HX600 (AMD Opteron processors) at Nagoya University. In this presentation, as a tuning technique, the MHD simulation model was run by using three decomposition methods for parallelization and one cache tuning method to find out which method is best for the MHD code. As a result we have obtained over 10% of peak performance efficiency using the T2K open supercomputer and we obtained much better performances with SR16000 and FX1, HX600 (over 20%). In particular we found that the two-dimensional decom-position of the MHD model is suitable for the T2K system and while for the SR16000 and FX1 cache tuned three-dimensional decomposition achieved the best performance. In this study we will show and compare the results of performance measurements and tuning techniques for MHD simulation codes of the planetary magnetospheres with scalar type supercomputers in detail. Finally we will present the latest simulation results of global planetary magnetosphere with high spatial resolution (three times the resolution of our current Saturn's model) using the result of performance tuning.
Experimental investigation of magnetohydrodynamic instabilities in a Magneto-Plasma-Dynamic thruster
NASA Astrophysics Data System (ADS)
Zuin, M.; Agostini, M.; Cavazzana, R.; Martines, E.; Serianni, P. Scarin G.; Antoni, V.; Bagatin, M.; Andrenucci, M.; Paganucci, F.; Rossetti, P.; Signori, M.
2004-09-01
An extensive experimental investigation has been carried out in order to understand the role of magnetohydrodynamic (MHD) instabilities on the reduced performance of Magneto-Plasma-Dynamic (MPD) thrusters when operating at high current. MPDs are electromagnetic plasma accelerators, currently under investigation as a possible, high-power electric propulsion option for primary space missions, whose thrust efficiency is limited by the onset of critical regimes observed when the current rises beyond a threshold value. Recently, it has been found (ZUIN M. et al. Phys. Rev. Lett., 95 (2004) 225003) that in these devices large-scale MHD helical kink mode instabilities develop, with m/n = 1/1 azimuthal and axial periodicity, and that the critical current condition is well described by the Kruskal-Shafranov criterion. In this paper the spatial structure of the kink has been reconstructed by magnetic and electrostatic probes and the results of two photomultiplier arrays, 16 channels each, collecting total radiation in the range 350-850 nm, confirm the helical structure of a kink with nonuniform pitch.
Toward 3D MHD modeling of neoclassical tearing mode suppression by ECCD
NASA Astrophysics Data System (ADS)
Pratt, J.; Westerhof, E.
2012-09-01
We propose a framework to extend the magnetohydrodynamic (MHD) equations to include electron cyclotron current drive (ECCD) and discuss previous models proposed by Giruzzi et al. [2] and by Hegna and Callen [3]. To model neoclassical tearing mode (NTM) instabilities and study the growth of magnetic islands as NTMs evolve, we employ the nonlinear reduced-MHD simulation JOREK. We present tearing-mode growth-rate calculations from JOREK simulations.
D.S. Darrow; S.S. Medley; A.L. Roquemore; W.W. Heidbrink; A. Alekseyev; F.E. Cecil; J. Egedal; V.Ya. Goloborod'ko; N.N. Gorelenkov; M. Isobe; S. Kaye; M. Miah; F. Paoletti; M.H. Redi; S.N. Reznik; A. Rosenberg; R. White; D. Wyatt; V.A. Yavorskij
2002-10-15
A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the {approx}25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong.
Magneto-hydrodynamics Simulation in Astrophysics
NASA Astrophysics Data System (ADS)
Pang, Bijia
2011-08-01
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 Alfvn 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.
NASA Technical Reports Server (NTRS)
Curtis, Steven
1999-01-01
Global MHD (magnetohydrodynamic) simulations have shown a remarkable ability to describe the global dynamics of geospace. The limitations of the physical approximations underlying MHD would seem to limit the effectiveness of these codes, since kinetic and hybrid effects should manifest themselves by cross-scale coupling from microscales to mesoscales to global scales. However three effects appear to allow the codes to operate much more successfully than one would at first believe. They are:(l) the globally self-consistent nature of the codes with very well defined exterior boundary conditions (the solar wind) which allows the proper intercommunication between magnetospheric regions on MHD scales, (2) the control by global dynamics of the boundary layer locations where micro and meso scale processes operate, and (3) the critical role of numerical diffusion and with a sufficiently high resolution grid, the use of an empirical resistivity term, which if set at a level where the major magnetosphere boundaries properly calibrate against their observed locations, appear to well represent the effects of kinetic and hybrid processes on the global dynamics. The effectiveness of the global MHD codes, which have been developed under the ISTP mission, in describing Wind, Polar and Geotail observations, as well as ground-based observations are described. Particular emphasis is placed upon the Polar imaging data which when combined with ground-based data and global MHD-based synthetic aurora and convection patterns provide a powerful tool in understanding the final link in the solar-terrestrial chain: coupling into the atmosphere and ionosphere.
Nonlinear magnetohydrodynamic stability
NASA Technical Reports Server (NTRS)
Bauer, F.; Betancourt, O.; Garabedian, P.
1981-01-01
The computer code developed by Bauer et al. (1978) for the study of the magnetohydrodynamic equilibrium and stability of a plasma in toroidal geometry is extended so that the growth rates of instabilities may be estimated more accurately. The original code, which is based on the variational principle of ideal magnetohydrodynamics, is upgraded by the introduction of a nonlinear formula for the growth rate of an unstable mode which acts as a quantitative measure of instability that is important in estimating numerical errors. The revised code has been applied to the determination of the nonlinear saturation, ballooning modes and beta limits for tokamaks, stellarators and torsatrons.
MHD instabilities in magneto-plasma-dynamic thrusters
NASA Astrophysics Data System (ADS)
Paganucci, F.; Zuin, M.; Agostini, M.; Andrenucci, M.; Antoni, V.; Bagatin, M.; Bonomo, F.; Cavazzana, R.; Franz, P.; Marrelli, L.; Martin, P.; Martines, E.; Rossetti, P.; Serianni, G.; Scarin, P.; Signori, M.; Spizzo, G.
2008-12-01
Magneto-plasma-dynamic thrusters (MPDTs) act as electromagnetic plasma accelerators and represent a high power, electric propulsion option for primary space missions. One of the major problems facing MPDT operation is the onset of a critical regime, which is found when the power is increased beyond a threshold value, depending mainly on the thruster geometry, the type and mass flow rate of the propellant and the intensity of the magnetic field applied. In this regime, large fluctuations in the electrode voltage signals, damage to the anode and decreased efficiency are observed. Since 2000, several test campaigns have been carried out to investigate the electrostatic and magnetic properties of plasma fluctuations using electromagnetic and optic probes and ultraviolet tomography. Results obtained have shown a strong relation between the onset phenomena and the growth of a large scale magnetohydrodynamic (MHD) instability, with helical kink mode features. On the basis of the experimental observations, a passive method to suppress instability is proposed and has been partially tested, with encouraging results.
Generalized entropy formulation of dissipative magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Rasband, S. N.; Mason, G. W.; Matheson, P. L.
1988-11-01
A variational-principle formulation of dissipative magnetohydrodynamics (DMHD) including thermal conduction and viscous dissipation as well as resistive decay is presented. The functional to be minimized is an extension of the generalized entropy-production (GEP) rate first discussed by I. Prigogine 2 [Nonequilibrium Thermodynamics, Variational Techniques, and Stability, edited by R. J. Donnelly, R. Herman, and I. Prigogine (University of Chicago Press, Chicago, 1966)]. Minimization of this functional at each instant of time results in the proper evolutionary behavior of the MHD fields while the correct boundary conditions are maintained. Steady-state solutions are obtained as a special case of the GEP functional minimization, which is fully consistent with earlier entropy formulations for the steady state. The method is illustrated with an explicit application to a simple, one-dimensional model of a reversed-field pinch.
COSMOLOGICAL ADAPTIVE MESH REFINEMENT MAGNETOHYDRODYNAMICS WITH ENZO
Collins, David C.; Xu Hao; Norman, Michael L.; Li Hui; Li Shengtai
2010-02-01
In this work, we present EnzoMHD, the extension of the cosmological code Enzo to include the effects of magnetic fields through the ideal magnetohydrodynamics approximation. We use a higher order Godunov method for the computation of interface fluxes. We use two constrained transport methods to compute the electric field from those interface fluxes, which simultaneously advances the induction equation and maintains the divergence of the magnetic field. A second-order divergence-free reconstruction technique is used to interpolate the magnetic fields in the block-structured adaptive mesh refinement framework already extant in Enzo. This reconstruction also preserves the divergence of the magnetic field to machine precision. We use operator splitting to include gravity and cosmological expansion. We then present a series of cosmological and non-cosmological test problems to demonstrate the quality of solution resulting from this combination of solvers.
MHD Stability of Polar Caps of Accreting Neutron Stars
NASA Astrophysics Data System (ADS)
Litwin, C.; Brown, E. F.; Rosner, R.
2000-12-01
We assess the stability of magnetic Rayleigh-Taylor type modes driven by the overpressure of magnetically confined accreted matter on the surface of a neutron star. We employ the magnetohydrodynamic (MHD) energy principle to analyze the stability of short-wavelength (ballooning) modes subject to line-tying in the neutron star crust. Research supported by ASCI/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago.
Statistics of passive tracers in three-dimensional magnetohydrodynamic turbulence
Busse, Angela; Mueller, Wolf-Christian; Homann, Holger; Grauer, Rainer
2007-12-15
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.
General polytropic magnetohydrodynamic cylinder under self-gravity
NASA Astrophysics Data System (ADS)
Lou, Yu-Qing; Xing, Heng-Rui
2016-02-01
Based on general polytropic (GP) magnetohydrodynamics (MHD), we offer a self-similar dynamic formalism for a magnetized, infinitely long, axially uniform cylinder of axisymmetry under self-gravity with radial and axial flows and with helical magnetic field. We identify two major classes of solution domains and obtain a few valuable MHD integrals in general. We focus on one class that has the freedom of prescribing a GP dynamic equation of state including the isothermal limit and derive analytic asymptotic solutions for illustration. In particular, we re-visit the isothermal MHD problem of Tilley & Pudritz (TP) and find that TP's main conclusion regarding the MHD solution behaviour for a strong ring magnetic field of constant toroidal flux-to-mass ratio Γϕ to be incorrect. As this is important for conceptual scenarios, MHD cylinder models, testing numerical codes and potential observational diagnostics of magnetized filaments in various astrophysical contexts, we show comprehensive theoretical analysis and reasons as well as extensive numerical results to clarify pertinent points in this Letter. In short, for any given Γϕ value be it small or large, the asymptotic radial scaling of the reduced mass density α(x) at sufficiently large x should always be ˜x-4 instead of ˜x-2 contrary to the major claim of TP.
A Meshless Method for Magnetohydrodynamics and Applications to Protoplanetary Disks
NASA Astrophysics Data System (ADS)
McNally, Colin P.
2012-08-01
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.
Analysis and design of an ultrahigh temperature hydrogen-fueled MHD generator
NASA Technical Reports Server (NTRS)
Moder, Jeffrey P.; Myrabo, Leik N.; Kaminski, Deborah A.
1993-01-01
A coupled gas dynamics/radiative heat transfer analysis of partially ionized hydrogen, in local thermodynamic equilibrium, flowing through an ultrahigh temperature (10,000-20,000 K) magnetohydrodynamic (MHD) generator is performed. Gas dynamics are modeled by a set of quasi-one-dimensional, nonlinear differential equations which account for friction, convective and radiative heat transfer, and the interaction between the ionized gas and applied magnetic field. Radiative heat transfer is modeled using nongray, absorbing-emitting 2D and 3D P-1 approximations which permit an arbitrary variation of the spectral absorption coefficient with frequency. Gas dynamics and radiative heat transfer are coupled through the energy equation and through the temperature- and density-dependent absorption coefficient. The resulting nonlinear elliptic problem is solved by iterative methods. Design of such MHD generators as onboard, open-cycle, electric power supplies for a particular advanced airbreathing propulsion concept produced an efficient and compact 128-MWe generator characterized by an extraction ratio of 35.5 percent, a power density of 10,500 MWe/cu m, and a specific (extracted) energy of 324 MJe/kg of hydrogen. The maximum wall heat flux and total wall heat load were 453 MW/sq m and 62 MW, respectively.
Electron magnetohydrodynamics: dynamics and turbulence.
Lyutikov, Maxim
2013-11-01
We consider dynamics and turbulent interaction of whistler modes within the framework of inertialess electron magnetohydrodynamics (EMHD). We argue that there is no energy principle in EMHD: any stationary closed configuration is neutrally stable. On the other hand, the relaxation principle, the long term evolution of a weakly dissipative system towards Taylor-Beltrami state, remains valid in EMHD. We consider the turbulent cascade of whistler modes. We show that (i) harmonic whistlers are exact nonlinear solutions; (ii) collinear whistlers do not interact (including counterpropagating); (iii) waves with the same value of the wave vector k(1)=k(2) 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 Alfvn 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 [proportionality]k(-2). The cascade remains weak (not critically balanced). The cascade is UV local, while the infrared locality is weakly (logarithmically) violated. PMID:24329368
Electron magnetohydrodynamics: Dynamics and turbulence
NASA Astrophysics Data System (ADS)
Lyutikov, Maxim
2013-11-01
We consider dynamics and turbulent interaction of whistler modes within the framework of inertialess electron magnetohydrodynamics (EMHD). We argue that there is no energy principle in EMHD: any stationary closed configuration is neutrally stable. On the other hand, the relaxation principle, the long term evolution of a weakly dissipative system towards Taylor-Beltrami state, remains valid in EMHD. We consider the turbulent cascade of whistler modes. We show that (i) harmonic whistlers are exact nonlinear solutions; (ii) collinear whistlers do not interact (including counterpropagating); (iii) waves with the same value of the wave vector k1=k2 do not interact; (iv) whistler modes have a dispersion that allows a three-wave decay, including into a zero frequency mode; (v) the three-wave interaction effectively couples modes with highly different wave numbers and propagation angles. In addition, linear interaction of a whistler with a single zero mode can lead to spatially divergent structures via parametric instability. All these properties are drastically different from MHD, so that the qualitative properties of the Alfvn 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.
NASA Astrophysics Data System (ADS)
Nazirov, R. R.; Rabinovich, B. I.; Mytarev, A. I.
2008-06-01
This paper is a continuation of [1 3] and a generalization of the results for a rotating spacecraft with cavities partially filled with liquid and equipped with an operational magnetohydrodynamic (MHD) element in the loop of its attitude control. This element makes possible the creation of hingeless systems of stabilization and orientation that do not require rocket propellant consumption. The application of an MHD element is considered for stabilization in the mode of spin-up of a spacecraft not having gyroscopic stability.
Dissipation of Molecular Cloud Turbulence by Magnetohydrodynamic Shockwaves
NASA Astrophysics Data System (ADS)
Lehmann, Andrew; Wardle, Mark
2015-08-01
The character of star formation is intimately related to the supersonic magnetohydrodynamic (MHD) turbulent dynamics of the giant molecular clouds in which stars form. A significant amount of the turbulent energy dissipates in low velocity shock waves. These shocks cause molecular line cooling of the compressed and heated gas, and so their radiative signatures probe the nature of the turbulence. In MHD fluids the three distinct families of shocksfast, intermediate and slowdiffer in how they compress and heat the molecular gas, and so observational differences between them may also distinguish driving modes of turbulent regions.Here we use a two-fluid model to compare the characteristics of one-dimensional fast and slow MHD shocks. Fast MHD shocks are magnetically driven, forcing ion species to stream through the neutral gas ahead of the shock front. This magnetic precursor heats the gas sufficiently to create a large, warm transition zone where all the fluid variables only weakly change in the shock front. In contrast, slow MHD shocks are driven by gas pressure where neutral species collide with ion species in a thin hot slab that closely resembles an ordinary gas dynamic shock.We computed observational diagnostics for fast and slow shocks at velocities vs = 2-4 km/s and preshock Hydrogen nuclei densities n(H) = 102-4 cm-3. We followed the abundances of molecules relevant for a simple oxygen chemistry and include cooling by CO, H2 and H2O. Estimates of intensities of CO rotational lines show that high-J lines, above J = 6?5, are more strongly excited in slow MHD shocks. We discuss how these shocks could help interpret recently observed anomalously strong mid- and high-J CO lines emitted by warm gas in the Milky Way and external galaxies, and implications for simulations of MHD turbulence.
Contributions from space technology to central power generation
NASA Technical Reports Server (NTRS)
Dicks, J. B., Jr.
1972-01-01
The central power crisis, and the present and relatively near-time contributions that aerospace technology is making to help solve this crisis are discussed. The principal emphasis is placed on the prospects of aerospace derived magnetohydrodynamic (MHD) large scale power generation. The strides that the Soviet Union is making in this field with the startup of the new U-25 plant near Moscow, having a total power capability of 75 MW, are reviewed. A much smaller program in the U.S. is outlined, and prospects of future benefits are discussed.
Large-scale quasi-geostrophic magnetohydrodynamics
Balk, Alexander M.
2014-12-01
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.
Validation of Magnetospheric Magnetohydrodynamic Models
NASA Astrophysics Data System (ADS)
Curtis, Brian
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.
Broken Ergodicity in MHD Turbulence in a Spherical Domain
NASA Technical Reports Server (NTRS)
Shebalin, John V.; wang, Yifan
2011-01-01
Broken ergodicity (BE) occurs in Fourier method numerical simulations of ideal, homogeneous, incompressible magnetohydrodynamic (MHD) turbulence. Although naive statistical theory predicts that Fourier coefficients of fluid velocity and magnetic field are zero-mean random variables, numerical simulations clearly show that low-wave-number coefficients have non-zero mean values that can be very large compared to the associated standard deviation. In other words, large-scale coherent structure (i.e., broken ergodicity) in homogeneous MHD turbulence can spontaneously grow out of random initial conditions. Eigenanalysis of the modal covariance matrices in the probability density functions of ideal statistical theory leads to a theoretical explanation of observed BE in homogeneous MHD turbulence. Since dissipation is minimal at the largest scales, BE is also relevant for resistive magnetofluids, as evidenced in numerical simulations. Here, we move beyond model magnetofluids confined by periodic boxes to examine BE in rotating magnetofluids in spherical domains using spherical harmonic expansions along with suitable boundary conditions. We present theoretical results for 3-D and 2-D spherical models and also present computational results from dynamical simulations of 2-D MHD turbulence on a rotating spherical surface. MHD turbulence on a 2-D sphere is affected by Coriolus forces, while MHD turbulence on a 2-D plane is not, so that 2-D spherical models are a useful (and simpler) intermediate stage on the path to understanding the much more complex 3-D spherical case.
Picologlou, B F; Batenin, V M
1980-07-01
A description of the modifications made to improve the plasma parameters of the U-25B Facility is presented. The oxygen enrichment system was modified to allow oxygen enrichment of up to 50% (by volume) ahead of the preheaters. Optimum design and operating conditions of the seed injection system were defined as a result of experimental investigations. An account of the extensive diagnostic studies performed and a description of the measurement techniques and of the new submillimeter laser interferometer are given. The performance of the MHD generator is analyzed for different operating modes. Studies of fluctuations and nonuniformities, current take-off distributions, local electrical analysis, overall heat transfer history of the MHD channel, and an extensive parametric study of the generator are presented. A detailed account of the complete disassembly and inspection of channel No. 1 after more than 100 hours of operation with the combustor, and of the condition of its various elements is also given.
Status of Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Lineberry, John T.
2007-01-01
Over the past several years, efforts have been under way to design and develop an operationally flexible research facility for investigating the use of cross-field MHD accelerators as a potential thrust augmentation device for thermal propulsion systems, The baseline configuration for this high-power experimental facility utilizes a 1,5-MW, multi-gas arc-heater as a thermal driver for a 2-MW, MHD accelerator, which resides in a large-bore 2-tesla electromagnet. A preliminary design study using NaK seeded nitrogen as the working fluid led to an externally diagonalized segmented MHD channel configuration based on an expendable beat-sink design concept. The current status report includes a review of engineering/design work and performance optimization analyses and summarizes component hardware fabrication and development efforts, preliminary testing results, and recent progress toward full-up assembly and testing
Outline of fast analyzer for MHD equilibrium FAME
NASA Astrophysics Data System (ADS)
Sakata, Shinya; Haginoya, Hirofumi; Tsuruoka, Takuya; Aoyagi, Tetsuo; Saito, Naoyuki; Harada, Hiroo; Tani, Keiji; Watanabe, Hideto
1994-02-01
The FAME (Fast Analyzer for Magnetohydrodynamic (MHD) Equilibrium) system has been developed in order to provide more than 100 MHD equilibria in time series which are enough for the non-stationary analysis of the experimental data of JT-60 within about 20 minutes shot interval. The FAME is an MIMD type small scale parallel computer with 20 microprocessors which are connected by a multi-stage switching system. The maximum theoretical speed is 250 MFLOPS. For the software system of FAME, MHD equilibrium analysis code SELENE and its input data production code FBI are tuned up taking the parallel processing into consideration. Consequently, the computational performance of the FAME system becomes more than 7 times faster than the existing general purpose computer FACOM M780-10s. This report summarizes the outline of the FAME system including hardware, soft-ware and peripheral equipments.
Evaluation of materials for the MHD steam bottoming plant
Natesan, K.; Swift, W.M.
1989-05-01
Test data have been obtained on the corrosion of several commercial ASME-coded alloys and their weldments by exposing internally cooled ring specimens to simulated magnetohydrodynamics (MHD) environments. The specimens, coated with a K/sub 2/SO/sub 4/-rich deposit, were exposed for times up to 2000 h at metal temperatures of 762, 593, and 567/degree/C to simulated MHD conditions for the intermediate-temperature air heater (ITAH), ITAH transition region (transition from a low- to medium-chromium alloy to a high-chromium steel), and secondary superheater (SSH), respectively. This paper discusses, in detail, the observed corrosion scale morphologies of various exposed specimens. Data on scale thickness, depth of intergranular penetration, and metal recession are presented, and the results are used to assess the corrosion behavior of various materials for application in the MHD steam bottoming plant. 6 refs., 7 figs., 3 tabs.
Large amplitude MHD waves upstream of the Jovian bow shock
NASA Technical Reports Server (NTRS)
Goldstein, M. L.; Smith, C. W.; Matthaeus, W. H.
1983-01-01
Observations of large amplitude magnetohydrodynamics (MHD) waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 mHz have a direction of minimum variance along the direction of the average magnetic field. The direction of minimum variance of these fluctuations lies at approximately 40 deg. to the magnetic field and is parallel to the radial direction. We argue that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the plasma rest frame. A linear instability analysis is presented which suggests an explanation for many of the observed features of the observations.
NASA Astrophysics Data System (ADS)
Branover, Herman; Mond, Michael; Unger, Yeshajahu
The present collection of papers on MHD-related uses of liquid metal flows and their applications discusses topics in laminar MHD flows, MHD power generation, metallurgical MHD applications, and two-phase MHD flows. Attention is given to MHD flows with closed streamlines, nonlinear waves in liquid metals under a transverse magnetic field, liquid-metal MHD conversion of nuclear energy to electricity, the testing of optimized MHD conversion ('OMACON') systems, and aspects of a liquid-metal induction generator. Also discussed are MHD effects in liquid-metal breeder reactors, a plasma-driven MHD powerplant, modeling the recirculating flows in channel-induction surfaces, the hydrodynamics of aluminum reduction cells, free-surface determination in a levitation-melting process, the parametric interactions of waves in bubbly liquid metals, and the occurrence of cavitation in water jets.
Branover, H.; Mond, M.; Unger, Y.
1988-01-01
The present collection of papers on MHD-related uses of liquid metal flows and their applications discusses topics in laminar MHD flows, MHD power generation, metallurgical MHD applications, and two-phase MHD flows. Attention is given to MHD flows with closed streamlines, nonlinear waves in liquid metals under a transverse magnetic field, liquid-metal MHD conversion of nuclear energy to electricity, the testing of optimized MHD conversion (OMACON) systems, and aspects of a liquid-metal induction generator. Also discussed are MHD effects in liquid-metal breeder reactors, a plasma-driven MHD powerplant, modeling the recirculating flows in channel-induction surfaces, the hydrodynamics of aluminum reduction cells, free-surface determination in a levitation-melting process, the parametric interactions of waves in bubbly liquid metals, and the occurrence of cavitation in water jets.
Optimum performance of MHD-augumented chemical rocket thrusters for space propulsion applications
Schulz, R.J.; Chapman, J.N.
1995-12-31
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.
NASA Technical Reports Server (NTRS)
Musielak, Z. E.; Rosner, R.
1988-01-01
Magnetohydrodynamic (MHD) wave energy fluxes for late-type stars are calculated, using previously obtained formulae for the source functions for the generation of MHD waves in a stratified, but otherwise uniform, turbulent atmosphere; the magnetic fields in the wave generation region are assumed to be homogeneous. In contradiction to previous results, it is shown that in this uniform magnetic field case there is no significant increase in the efficiency of MHD wave generation, at least within the theory's limits of applicability. The major results are that the MHD energy fluxes calculated for late-type stars are less than those obtained for compressible modes in the magnetic field-free case, and that these MHD energy fluxes do not vary enough for a given spectral type to explain the observed range of UV and X-ray fluxes from such stars. It is therefore concluded that MHD waves in stellar atmospheres with homogeneous magnetic fields in the wave generation region cannot explain the observed stellar coronal emissions; if such MHD waves are responsible for a significant component of stellar coronal heating, then nonuniform fields within the generation region must be appealed to.
Numerical Simulation of Turbulent MHD Flows Using an Iterative PNS Algorithm
NASA Technical Reports Server (NTRS)
Kato, Hiromasa; Tannehill, John C.; Mehta, Unmeel B.
2003-01-01
A new parabolized Navier-Stokes (PNS) algorithm has been developed to efficiently compute magnetohydrodynamic (MHD) flows in the low magnetic Reynolds number regime. In this regime, the electrical conductivity is low and the induced magnetic field is negligible compared to the applied magnetic field. The MHD effects are modeled by introducing source terms into the PNS equation which can then be solved in a very efficient manner. To account for upstream (elliptic) effects, the flowfields are computed using multiple streamwise sweeps with an iterated PNS algorithm. Turbulence has been included by modifying the Baldwin-Lomax turbulence model to account for MHD effects. The new algorithm has been used to compute both laminar and turbulent, supersonic, MHD flows over flat plates and supersonic viscous flows in a rectangular MHD accelerator. The present results are in excellent agreement with previous complete Navier-Stokes calculations.
NASA Technical Reports Server (NTRS)
Kabin, K.; Hansen, K. C.; Gombosi, T. I.; Combi, M. R.; Linde, T. J.; DeZeeuw, D. L.; Groth, C. P. T.; Powell, K. G.; Nagy, A. F.
2000-01-01
Magnetohydrodynamics (MHD) provides an approximate description of a great variety of processes in space physics. Accurate numerical solutions of the MHD equations are still a challenge, but in the past decade a number of robust methods have appeared. Once these techniques made the direct solution of MHD equations feasible, a number of global three-dimensional models were designed and applied to many space physics objects. The range of these objects is truly astonishing, including active galactic nuclei, the heliosphere, the solar corona, and the solar wind interaction with planets, satellites, and comets. Outside the realm of space physics, MHD theory has been applied to such diverse problems as laboratory plasmas and electromagnetic casting of liquid metals. In this paper we present a broad spectrum of models of different phenomena in space science developed in the recent years at the University of Michigan. Although the physical systems addressed by these models are different, they all use the MHD equations as a unifying basis.
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, J.C.; Swift, G.W.; Migliori, A.
1984-11-16
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.
Thermoacoustic magnetohydrodynamic electrical generator
Wheatley, John C. (Los Alamos, NM); Swift, Gregory W. (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)
1986-01-01
A thermoacoustic magnetohydrodynamic electrical generator includes an intrinsically irreversible thermoacoustic heat engine coupled to a magnetohydrodynamic electrical generator. The heat engine includes an electrically conductive liquid metal as the working fluid and includes two heat exchange and thermoacoustic structure assemblies which drive the liquid in a push-pull arrangement to cause the liquid metal to oscillate at a resonant acoustic frequency on the order of 1,000 Hz. The engine is positioned in the field of a magnet and is oriented such that the liquid metal oscillates in a direction orthogonal to the field of the magnet, whereby an alternating electrical potential is generated in the liquid metal. Low-loss, low-inductance electrical conductors electrically connected to opposite sides of the liquid metal conduct an output signal to a transformer adapted to convert the low-voltage, high-current output signal to a more usable higher voltage, lower current signal.
NASA Astrophysics Data System (ADS)
Raphaldini, Breno; Raupp, Carlos F. M.
2015-01-01
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.
MHD Coal-Fired Flow Facility. Quarterly/annual technical progress report, October-December 1979
Dicks, J. B.; Chapman, J. N.; Crawford, L. W.
1980-02-01
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.
Theoretical study of anisotropic MHD turbulence with low magnetic Reynolds number
NASA Astrophysics Data System (ADS)
Sukoriansky, Semion; Zemach, Efi
2016-03-01
Flows of electrically conducting fluids under the action of external magnetic field present an example of strongly anisotropic turbulence. Such flows are not only important for different engineering applications, but also provide an interesting framework for studies of quasi-two-dimensional turbulence with strongly modified transport properties in easily controllable laboratory experiments. We present theoretical results that advance our understanding of magnetohydrodynamic (MHD) flows with low magnetic Reynolds number by treating this phenomenon within the quasi-normal scale elimination (QNSE) theory. Previous applications of the theory to turbulent flows with stable stratification and solid body rotation have demonstrated that QNSE is a powerful tool for studies of anisotropic turbulent flows. We derive expressions for scale-dependent eddy viscosities and eddy diffusivities in the directions parallel and normal to the external magnetic field and investigate progressive anisotropization of turbulent transport of momentum and passive scalar. The theory yields analytical expressions for anisotropic one-dimensional spectra of MHD turbulence. In particular, the theory sheds light upon the modification of the Kolmogorov k‑5/3 spectrum by anisotropic Ohmic (Joule) dissipation.
Ballooning modes in the magnetohydrodynamic second stability region
Nordman, H.; Jarmen, A.; Malinov, P.; Persson, M.
1995-09-01
The ion temperature gradient driven ballooning mode is investigated using two-fluid, gyrofluid, and gyrokinetic descriptions. The linear eigenmode equation is solved numerically in a model equilibrium with shifted circular magnetic surfaces. The localization of the eigenmodes, which persist in the magnetohydrodynamic (MHD) second stability region, and the mode structure, are displayed. The role of finite-Larmor radius (FLR) and magnetic drift resonance effects on the growth rate are elucidated. Negative magnetic shear is found to have a stabilizing effect on the mode. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Magnetic reversals in a simple model of magnetohydrodynamics.
Benzi, Roberto; Pinton, Jean-François
2010-07-01
We study a simple magnetohydrodynamical approach in which hydrodynamics and MHD turbulence are coupled in a shell model, with given dynamo constraints in the large scales. We consider the case of a low Prandtl number fluid for which the inertial range of the velocity field is much wider than that of the magnetic field. Random reversals of the magnetic field are observed and it shown that the magnetic field has a nontrivial evolution--linked to the nature of the hydrodynamics turbulence. PMID:20867710
The role of magnetohydrodynamics in heliospheric space plasma physics research
NASA Technical Reports Server (NTRS)
Dryer, Murray; Smith, Zdenka Kopal; Wu, Shi Tsan
1988-01-01
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.
MAGNETOHYDRODYNAMIC SIMULATION OF A SIGMOID ERUPTION OF ACTIVE REGION 11283
Jiang Chaowei; Feng Xueshang; Wu, S. T.; Hu Qiang E-mail: fengx@spaceweather.ac.cn E-mail: qh0001@uah.edu
2013-07-10
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.
Turbulent two-dimensional magnetohydrodynamics and conformal field theory
Rahimi Tabar, M.R.; Rouhani, S.
1996-03-01
We show that an infinite number of non-unitary minimal models may describe two dimensional turbulent magnetohydrodynamics (MHD), both in the presence and absence of the Alf{close_quote}ven effect. We argue that the existence of a critical dynamical index results in the Alf{close_quote}ven effect or equivalently the equipartition of energy. We show that there are an infinite number of conserved quantities in 2{ital D}{endash}{ital MHD} turbulent systems both in the limit of vanishing the viscocities and in force free case. In the force free case, using the non-unitary minimal model {ital M}{sub 2,7} we derive the correlation functions for the velocity stream function and magnetic flux function. Generalizing this simple model we find the exponents of the energy spectrum in the inertial range for a class of conformal field theories. Copyright {copyright} 1996 Academic Press, Inc.
Multi-symplectic magnetohydrodynamics: II, addendum and erratum
NASA Astrophysics Data System (ADS)
Webb, G. M.; McKenzie, J. F.; Zank, G. P.
2015-12-01
> A recent paper by Webb et al. (J. Plasma Phys., vol. 80, 2014, pp. 707-743) on multi-symplectic magnetohydrodynamics (MHD) using Clebsch variables in an Eulerian action principle with constraints is further extended. We relate a class of symplecticity conservation laws to a vorticity conservation law, and provide a corrected form of the Cartan-Poincar differential form formulation of the system. We also correct some typographical errors (omissions) in Webb et al. (J. Plasma Phys., vol. 80, 2014, pp. 707-743). We show that the vorticity-symplecticity conservation law, that arises as a compatibility condition on the system, expressed in terms of the Clebsch variables is equivalent to taking the curl of the conservation form of the MHD momentum equation. We use the Cartan-Poincar form to obtain a class of differential forms that represent the system using Cartan's geometric theory of partial differential equations
A renormalization group analysis of two-dimensional magnetohydrodynamic turbulence
NASA Technical Reports Server (NTRS)
Liang, Wenli Z.; Diamond, P. H.
1993-01-01
The renormalization group (RNG) method is used to study the physics of two-dimensional (2D) magnetohydrodynamic (MHD) turbulence. It is shown that, for a turbulent magnetofluid in two dimensions, no RNG transformation fixed point exists on account of the coexistence of energy transfer to small scales and mean-square magnetic flux transfer to large scales. The absence of a fixed point renders the RNG method incapable of describing the 2D MHD system. A similar conclusion is reached for 2D hydrodynamics, where enstrophy flows to small scales and energy to large scales. These analyses suggest that the applicability of the RNG method to turbulent systems is intrinsically limited, especially in the case of systems with dual-direction transfer.
Hamiltonian magnetohydrodynamics: Lagrangian, Eulerian, and dynamically accessible stability—Theory
Andreussi, T.; Morrison, P. J.; Pegoraro, F.
2013-09-15
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.
Disk Emission from Magnetohydrodynamic Simulations of Spinning Black Holes
NASA Astrophysics Data System (ADS)
Schnittman, Jeremy D.; Krolik, Julian H.; Noble, Scott C.
2016-03-01
We present the results of a new series of global, three-dimensional, relativistic magnetohydrodynamic (MHD) simulations of thin accretion disks around spinning black holes. The disks have aspect ratios of H/R∼ 0.05 and spin parameters of a/M=0,0.5,0.9, and 0.99. Using the ray-tracing code Pandurata, we generate broadband thermal spectra and polarization signatures from the MHD simulations. We find that the simulated spectra can be well fit with a simple, universal emissivity profile that better reproduces the behavior of the emission from the inner disk, compared to traditional analyses carried out using a Novikov–Thorne thin disk model. Finally, we show how spectropolarization observations can be used to convincingly break the spin-inclination degeneracy well known to the continuum-fitting method of measuring black hole spin.
Cross-helicity dynamo effect in magnetohydrodynamic turbulent channel flow
Hamba, Fujihiro; Tsuchiya, Masataka
2010-01-15
A large eddy simulation of magnetohydrodynamic (MHD) turbulent channel flow is carried out to investigate the dynamo mechanism. It is shown that the streamwise component of the mean magnetic field is generated and sustained due to the effect of the turbulent electromotive force. The Reynolds-averaged turbulence model for MHD flows is assessed; it is suggested that the cross-helicity dynamo effect contributes to the turbulent electromotive force; that is, the electromotive force parallel to the mean vorticity is generated due to the turbulent cross helicity. To verify the importance of the cross-helicity dynamo, the transport equation for the turbulent electromotive force is evaluated; it is confirmed that the term involving the cross helicity and the mean vorticity is the main production term for the turbulent electromotive force. The transport equations for the turbulent kinetic and magnetic energies are also examined to discuss the dynamo mechanism from the viewpoint of the energy transfer.
Global magnetohydrodynamic instabilities in the L-2M stellarator
NASA Astrophysics Data System (ADS)
Mikhailov, M. I.; Shchepetov, S. V.; Nhrenberg, C.; Nhrenberg, J.
2015-12-01
Analysis of global magnetohydrodynamic (MHD) instabilities in the L-2M stellarator (Prokhorov General Physics Institute, Russian Academy of Sciences) is presented. The properties of free-boundary equilibria states are outlined, the stability conditions for small-scale modes are briefly discussed, and the number of trapped particles is estimated. All the magnetic configurations under study are stable against ballooning modes. It is shown that global ideal internal MHD modes can be found reliably only in Mercier unstable plasmas. In plasma that is stable with respect to the Mercier criterion, global unstable modes that are localized in the vicinity of the free plasma boundary and are not associated with any rational magnetic surface inside the plasma (the so-called peeling modes) can be found. The radial structure of all perturbations under study is almost entirely determined by the poloidal coupling of harmonics. The results of calculations are compared with the available experimental data.
NASA Astrophysics Data System (ADS)
Webb, G. M.; Dasgupta, B.; McKenzie, J. F.; Hu, Q.; Zank, G. P.
2014-03-01
Conservation laws in ideal gas dynamics and magnetohydrodynamics (MHD) associated with fluid relabeling symmetries are derived using Noether's first and second theorems. Lie dragged invariants are discussed in terms of the MHD Casimirs. A nonlocal conservation law for fluid helicity applicable for a non-barotropic fluid involving Clebsch variables is derived using Noether's theorem, in conjunction with a fluid relabeling symmetry and a gauge transformation. A nonlocal cross helicity conservation law involving Clebsch potentials, and the MHD energy conservation law are derived by the same method. An Euler-Poincaré variational approach is also used to derive conservation laws associated with fluid relabeling symmetries using Noether's second theorem.
NASA Astrophysics Data System (ADS)
Vigh, C. D.; Cohet, R.; Marcowith, A.
2015-08-01
The interaction between cosmic rays and partially-ionized astrophysical fluids is mediated by magnetic fields. Magnetic fields in the interstellar medium (ISM) are highly turbulent and the magnetohydrodynamic (MHD) turbulence is anisotropic and intermittent. To investigate the mutual interaction between magnetized fluids and cosmic rays (CR) we incorporated in the MHD code RAMSES one module that couples turbulence forcing and the dynamic equation for cosmic rays in MHD equations. We present some preliminar cases and discuss the interaction between magnetic field, ISM gas density and CR gas.
An approximate Riemann solver for magnetohydrodynamics (that works in more than one dimension)
NASA Technical Reports Server (NTRS)
Powell, Kenneth G.
1994-01-01
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.
Minimum energy states of the cylindrical plasma pinch in single-fluid and Hall magnetohydrodynamics
Khalzov, I. V.; Schnack, D. D.; Mirnov, V. V.; Ebrahimi, F.
2012-01-15
Relaxed states of a plasma column are found analytically in single-fluid and Hall magnetohydrodynamics (MHD). We perform complete minimization of the energy with constraints imposed by invariants inherent in the corresponding models. It is shown that the relaxed state in Hall MHD is a force-free magnetic field with uniform axial flow and/or rigid azimuthal rotation. In contrast, the relaxed states in single-fluid MHD are more complex due to the coupling between velocity and magnetic field. Cylindrically and helically symmetric relaxed states are considered for both models. Helical states may be time dependent and analogous to helical waves, propagating on a cylindrically symmetric background. Application of our results to reversed-field pinches (RFP) is discussed. The radial profile of the parallel momentum predicted by the single-fluid MHD relaxation theory is shown to be in reasonable agreement with experimental observation from the Madison symmetric torus RFP experiment.
Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013
NASA Astrophysics Data System (ADS)
Paral, J.; Hudson, M. K.; Kress, B. T.; Wiltberger, M. J.; Wygant, J. R.; Singer, H. J.
2015-08-01
Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) magnetospheric simulation code coupled to the Rice Convection Model (RCM). Two other storms with strong magnetopause compression, 8-9 October 2012 and 17-18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015) of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) instrument on the Van Allen Probes.
A pressure-based high resolution numerical method for resistive MHD
NASA Astrophysics Data System (ADS)
Xisto, Carlos M.; Pscoa, Jos C.; Oliveira, Paulo J.
2014-10-01
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.
Local conservative regularizations of compressible magnetohydrodynamic and neutral flows
NASA Astrophysics Data System (ADS)
Krishnaswami, Govind S.; Sachdev, Sonakshi; Thyagaraja, A.
2016-02-01
Ideal systems like magnetohydrodynamics (MHD) and Euler flow may develop singularities in vorticity ( w =∇×v ). Viscosity and resistivity provide dissipative regularizations of the singularities. In this paper, we propose a minimal, local, conservative, nonlinear, dispersive regularization of compressible flow and ideal MHD, in analogy with the KdV regularization of the 1D kinematic wave equation. This work extends and significantly generalizes earlier work on incompressible Euler and ideal MHD. It involves a micro-scale cutoff length λ which is a function of density, unlike in the incompressible case. In MHD, it can be taken to be of order the electron collisionless skin depth c/ωpe. Our regularization preserves the symmetries of the original systems and, with appropriate boundary conditions, leads to associated conservation laws. Energy and enstrophy are subject to a priori bounds determined by initial data in contrast to the unregularized systems. A Hamiltonian and Poisson bracket formulation is developed and applied to generalize the constitutive relation to bound higher moments of vorticity. A "swirl" velocity field is identified, and shown to transport w/ρ and B/ρ, generalizing the Kelvin-Helmholtz and Alfvén theorems. The steady regularized equations are used to model a rotating vortex, MHD pinch, and a plane vortex sheet. The proposed regularization could facilitate numerical simulations of fluid/MHD equations and provide a consistent statistical mechanics of vortices/current filaments in 3D, without blowup of enstrophy. Implications for detailed analyses of fluid and plasma dynamic systems arising from our work are briefly discussed.
Multidimensional HLLE Riemann solver: Application to Euler and magnetohydrodynamic flows
NASA Astrophysics Data System (ADS)
Balsara, Dinshaw S.
2010-03-01
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.
Neoclassical viscosity effects on resistive magnetohydrodynamic modes in toroidal geometry
Yang, J.G.; Oh, Y.H.; Choi, D.I. ); Kim, J.Y.; Horton, W. )
1992-03-01
The flux-surface-averaged linearized resistive magnetohydrodynamic (MHD) boundary-layer equations including the compressibility, diamagnetic drift, and neoclassical viscosity terms are derived in toroidal geometry. These equations describe the resistive layer dynamics of resistive MHD modes over the collisionality regime between the banana plateau and the Pfirsch--Schlueter. From the resulting equations, the effects of neoclassical viscosity on the stability of the tearing and resistive ballooning modes are investigated numerically. Also, a study is given for the problem of how the neoclassical resistive MHD mode is generated as the collisionality is reduced. It is shown that the neoclassical viscosity terms give a significant destabilizing effect for the tearing and resistive ballooning modes. This destabilization comes mainly from the reduction of the stabilizing effect of the parallel ion sound compression by the ion neoclassical viscosity. In the banana-plateau collisionality limit, where the compressibility is negligible, the dispersion relations of the tearing and resistive ballooning modes reduce to the same form, with the threshold value of the driving force given by {Delta}{sub {ital c}}=0. On the other hand, with the finite neoclassical effect it is found that the neoclassical resistive MHD instability is generated in agreement with previous results. Furthermore, it is shown that this later instability can be generated in a wide range of the collisionality including near the Pfirsch--Schlueter regime as well as the banana-plateau regime, suggesting that this mode is a probable cause of anomalous transport.
Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Airbreathing Hypersonic Engines
NASA Technical Reports Server (NTRS)
Litchford, Ron J.; Bityurin, Valentine A.; Lineberry, John T.
1999-01-01
Established analyses of conventional ramjet/scramjet performance characteristics indicate that a considerable decrease in efficiency can be expected at off-design flight conditions. This can be explained, in large part, by the deterioration of intake mass flow and limited inlet compression at low flight speeds and by the onset of thrust degradation effects associated with increased burner entry temperature at high flight speeds. In combination, these effects tend to impose lower and upper Mach number limits for practical flight. It has been noted, however, that Magnetohydrodynamic (MHD) energy management techniques represent a possible means for extending the flight Mach number envelope of conventional engines. By transferring enthalpy between different stages of the engine cycle, it appears that the onset of thrust degradation may be delayed to higher flight speeds. Obviously, the introduction of additional process inefficiencies is inevitable with this approach, but it is believed that these losses are more than compensated through optimization of the combustion process. The fundamental idea is to use MHD energy conversion processes to extract and bypass a portion of the intake kinetic energy around the burner. We refer to this general class of propulsion system as an MHD-bypass engine. In this paper, we quantitatively assess the performance potential and scientific feasibility of MHD-bypass airbreathing hypersonic engines using ideal gasdynamics and fundamental thermodynamic principles.
Forest, C. B.
2002-11-15
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.
Statistical Theory of the Ideal MHD Geodynamo
NASA Technical Reports Server (NTRS)
Shebalin, J. V.
2012-01-01
A statistical theory of geodynamo action is developed, using a mathematical model of the geodynamo as a rotating outer core containing an ideal (i.e., no dissipation), incompressible, turbulent, convecting magnetofluid. On the concentric inner and outer spherical bounding surfaces the normal components of the velocity, magnetic field, vorticity and electric current are zero, as is the temperature fluctuation. This allows the use of a set of Galerkin expansion functions that are common to both velocity and magnetic field, as well as vorticity, current and the temperature fluctuation. The resulting dynamical system, based on the Boussinesq form of the magnetohydrodynamic (MHD) equations, represents MHD turbulence in a spherical domain. These basic equations (minus the temperature equation) and boundary conditions have been used previously in numerical simulations of forced, decaying MHD turbulence inside a sphere [1,2]. Here, the ideal case is studied through statistical analysis and leads to a prediction that an ideal coherent structure will be found in the form of a large-scale quasistationary magnetic field that results from broken ergodicity, an effect that has been previously studied both analytically and numerically for homogeneous MHD turbulence [3,4]. The axial dipole component becomes prominent when there is a relatively large magnetic helicity (proportional to the global correlation of magnetic vector potential and magnetic field) and a stationary, nonzero cross helicity (proportional to the global correlation of velocity and magnetic field). The expected angle of the dipole moment vector with respect to the rotation axis is found to decrease to a minimum as the average cross helicity increases for a fixed value of magnetic helicity and then to increase again when average cross helicity approaches its maximum possible value. Only a relatively small value of cross helicity is needed to produce a dipole moment vector that is aligned at approx.10deg with the rotation axis.
Basu, Abhik; Naji, Ali; Pandit, Rahul
2014-01-01
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
Etienne, Zachariah B.; Liu, Yuk Tung; Shapiro, Stuart L.
2010-10-15
We have written and tested a new general relativistic magnetohydrodynamics code, capable of evolving magnetohydrodynamics (MHD) fluids in dynamical spacetimes with adaptive-mesh refinement (AMR). Our code solves the Einstein-Maxwell-MHD system of coupled equations in full 3+1 dimensions, evolving the metric via the Baumgarte-Shapiro Shibata-Nakamura formalism and the MHD and magnetic induction equations via a conservative, high-resolution shock-capturing scheme. The induction equations are recast as an evolution equation for the magnetic vector potential, which exists on a grid that is staggered with respect to the hydrodynamic and metric variables. The divergenceless constraint {nabla}{center_dot}B=0 is enforced by the curl of the vector potential. Our MHD scheme is fully compatible with AMR, so that fluids at AMR refinement boundaries maintain {nabla}{center_dot}B=0. In simulations with uniform grid spacing, our MHD scheme is numerically equivalent to a commonly used, staggered-mesh constrained-transport scheme. We present code validation test results, both in Minkowski and curved spacetimes. They include magnetized shocks, nonlinear Alfven waves, cylindrical explosions, cylindrical rotating disks, magnetized Bondi tests, and the collapse of a magnetized rotating star. Some of the more stringent tests involve black holes. We find good agreement between analytic and numerical solutions in these tests, and achieve convergence at the expected order.