Nonlinear 2D convection and enhanced cross-field plasma transport near the MHD instability threshold

International Nuclear Information System (INIS)

Pastukhov, V.P.; Chudin, N.V.

2003-01-01

Results of theoretical study and computer simulations of nonlinear 2D convection induced by a convective MHD instability near its threshold in FRC-like non-paraxial magnetic confinement system are presented. An appropriate closed set of weakly nonideal reduced MHD equations is derived to describe the self-consistent plasma dynamics. It is shown that the convection forms nonlinear large scale stochastic vortices (convective cells), which tend to restore and to maintain the marginally stable pressure pro e and result in an essentially nonlocal enhanced heat transport. A large amount of data on the structure of the nascent convective flows is obtained and analyzed. The computer simulations of long time plasma evolutions demonstrate such features of the resulting anomalous transport as pro e consistency, L-H transition, external transport barrier, pinch of impurities, etc. (author)

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1981-03-01

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

Extended MHD Effects in High Energy Density Experiments

Science.gov (United States)

Seyler, Charles

2016-10-01

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

MHD stability properties of a system of reduced toroidal MHD equations

International Nuclear Information System (INIS)

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

1993-01-01

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

Performance and flow characteristics of MHD seawater thruster

Energy Technology Data Exchange (ETDEWEB)

Doss, E.D.

1990-01-01

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

A Fast MHD Code for Gravitationally Stratified Media using Graphical Processing Units: SMAUG

Science.gov (United States)

Griffiths, M. K.; Fedun, V.; Erdélyi, R.

2015-03-01

Parallelization techniques have been exploited most successfully by the gaming/graphics industry with the adoption of graphical processing units (GPUs), possessing hundreds of processor cores. The opportunity has been recognized by the computational sciences and engineering communities, who have recently harnessed successfully the numerical performance of GPUs. For example, parallel magnetohydrodynamic (MHD) algorithms are important for numerical modelling of highly inhomogeneous solar, astrophysical and geophysical plasmas. Here, we describe the implementation of SMAUG, the Sheffield Magnetohydrodynamics Algorithm Using GPUs. SMAUG is a 1-3D MHD code capable of modelling magnetized and gravitationally stratified plasma. The objective of this paper is to present the numerical methods and techniques used for porting the code to this novel and highly parallel compute architecture. The methods employed are justified by the performance benchmarks and validation results demonstrating that the code successfully simulates the physics for a range of test scenarios including a full 3D realistic model of wave propagation in the solar atmosphere.

Several hundred megawatt MHD units

International Nuclear Information System (INIS)

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

1978-01-01

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

Several hundred megawatt MHD units

Energy Technology Data Exchange (ETDEWEB)

Pishchikov, S; Pinkhasik, D; Sidorov, V

1978-07-01

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

Criteria for Scaled Laboratory Simulations of Astrophysical MHD Phenomena

International Nuclear Information System (INIS)

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

2000-01-01

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

Implementation of a 3-D nonlinear MHD [magnetohydrodynamics] calculation on the Intel hypercube

International Nuclear Information System (INIS)

Lynch, V.E.; Carreras, B.A.; Drake, J.B.; Hicks, H.R.; Lawkins, W.F.

1987-01-01

The optimization of numerical schemes and increasing computer capabilities in the last ten years have improved the efficiency of 3-D nonlinear resistive MHD calculations by about two to three orders of magnitude. However, we are still very limited in performing these types of calculations. Hypercubes have a large number of processors with only local memory and bidirectional links among neighbors. The Intel Hypercube at Oak Ridge has 64 processors with 0.5 megabytes of memory per processor. The multiplicity of processors opens new possibilities for the treatment of such computations. The constraint on time and resources favored the approach of using the existing RSF code which solves as an initial value problem the reduced set of MHD equations for a periodic cylindrical geometry. This code includes minimal physics and geometry, but contains the basic three dimensionality and nonlinear structure of the equations. The code solves the reduced set of MHD equations by Fourier expansion in two angular coordinates and finite differences in the radial one. Due to the continuing interest in these calculations and the likelihood that future supercomputers will take greater advantage of parallelism, the present study was initiated by the ORNL Exploratory Studies Committee and funded entirely by Laboratory Discretionary Funds. The objectives of the study were: to ascertain the suitability of MHD calculation for parallel computation, to design and implement a parallel algorithm to perform the computations, and to evaluate the hypercube, and in particular, ORNL's Intel iPSC, for use in MHD computations

Diagnostic development and support of MHD test facilities

Energy Technology Data Exchange (ETDEWEB)

1990-01-01

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

Diagnostic development and support of MHD test facilities

International Nuclear Information System (INIS)

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

1990-01-01

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

Nonlinear evolution of MHD instabilities

International Nuclear Information System (INIS)

Bateman, G.; Hicks, H.R.; Wooten, J.W.; Dory, R.A.

1975-01-01

A 3-D nonlinear MHD computer code was used to study the time evolution of internal instabilities. Velocity vortex cells are observed to persist into the nonlinear evolution. Pressure and density profiles convect around these cells for a weak localized instability, or convect into the wall for a strong instability. (U.S.)

A MHD channel study for the ETF conceptual design

Science.gov (United States)

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

1981-01-01

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

Demonstration of blind quantum computing.

Science.gov (United States)

Barz, Stefanie; Kashefi, Elham; Broadbent, Anne; Fitzsimons, Joseph F; Zeilinger, Anton; Walther, Philip

2012-01-20

Quantum computers, besides offering substantial computational speedups, are also expected to preserve the privacy of a computation. We present an experimental demonstration of blind quantum computing in which the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. Various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover quantum algorithms, are demonstrated. The client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available.

Magnetohydrodynamic (MHD) power generation

International Nuclear Information System (INIS)

Chandra, Avinash

1980-01-01

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

The Statistical Mechanics of Ideal MHD Turbulence

Science.gov (United States)

Shebalin, John V.

2003-01-01

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

MHD-flow in slotted channels with conducting walls

International Nuclear Information System (INIS)

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

1994-07-01

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

The CHEASE code for toroidal MHD equilibria

International Nuclear Information System (INIS)

Luetjens, H.

1996-03-01

CHEASE solves the Grad-Shafranov equation for the MHD equilibrium of a Tokamak-like plasma with pressure and current profiles specified by analytic forms or sets of data points. Equilibria marginally stable to ballooning modes or with a prescribed fraction of bootstrap current can be computed. The code provides a mapping to magnetic flux coordinates, suitable for MHD stability calculations or global wave propagation studies. The code computes equilibrium quantities for the stability codes ERATO, MARS, PEST, NOVA-W and XTOR and for the global wave propagation codes LION and PENN. The two-dimensional MHD equilibrium (Grad-Shafranov) equation is solved in variational form. The discretization uses bicubic Hermite finite elements with continuous first order derivates for the poloidal flux function Ψ. The nonlinearity of the problem is handled by Picard iteration. The mapping to flux coordinates is carried out with a method which conserves the accuracy of the cubic finite elements. The code uses routines from the CRAY libsci.a program library. However, all these routines are included in the CHEASE package itself. If CHEASE computes equilibrium quantities for MARS with fast Fourier transforms, the NAG library is required. CHEASE is written in standard FORTRAN-77, except for the use of the input facility NAMELIST. CHEASE uses variable names with up to 8 characters, and therefore violates the ANSI standard. CHEASE transfers plot quantities through an external disk file to a plot program named PCHEASE using the UNIRAS or the NCAR plot package. (author) figs., tabs., 34 refs

The CHEASE code for toroidal MHD equilibria

Energy Technology Data Exchange (ETDEWEB)

Luetjens, H. [Ecole Polytechnique, 91 - Palaiseau (France). Centre de Physique Theorique; Bondeson, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Inst. for Electromagnetic Field Theory and Plasma Physics; Sauter, O. [ITER-San Diego, La Jolla, CA (United States)

1996-03-01

CHEASE solves the Grad-Shafranov equation for the MHD equilibrium of a Tokamak-like plasma with pressure and current profiles specified by analytic forms or sets of data points. Equilibria marginally stable to ballooning modes or with a prescribed fraction of bootstrap current can be computed. The code provides a mapping to magnetic flux coordinates, suitable for MHD stability calculations or global wave propagation studies. The code computes equilibrium quantities for the stability codes ERATO, MARS, PEST, NOVA-W and XTOR and for the global wave propagation codes LION and PENN. The two-dimensional MHD equilibrium (Grad-Shafranov) equation is solved in variational form. The discretization uses bicubic Hermite finite elements with continuous first order derivates for the poloidal flux function {Psi}. The nonlinearity of the problem is handled by Picard iteration. The mapping to flux coordinates is carried out with a method which conserves the accuracy of the cubic finite elements. The code uses routines from the CRAY libsci.a program library. However, all these routines are included in the CHEASE package itself. If CHEASE computes equilibrium quantities for MARS with fast Fourier transforms, the NAG library is required. CHEASE is written in standard FORTRAN-77, except for the use of the input facility NAMELIST. CHEASE uses variable names with up to 8 characters, and therefore violates the ANSI standard. CHEASE transfers plot quantities through an external disk file to a plot program named PCHEASE using the UNIRAS or the NCAR plot package. (author) figs., tabs., 34 refs.

Flow aerodynamics modeling of an MHD swirl combustor - calculations and experimental verification

International Nuclear Information System (INIS)

Gupta, A.K.; Beer, J.M.; Louis, J.F.; Busnaina, A.A.; Lilley, D.G.

1981-01-01

This paper describes a computer code for calculating the flow dynamics of constant density flow in the second stage trumpet shaped nozzle section of a two stage MHD swirl combustor for application to a disk generator. The primitive pressure-velocity variable, finite difference computer code has been developed to allow the computation of inert nonreacting turbulent swirling flows in an axisymmetric MHD model swirl combustor. The method and program involve a staggered grid system for axial and radial velocities, and a line relaxation technique for efficient solution of the equations. Tue produces as output the flow field map of the non-dimensional stream function, axial and swirl velocity. 19 refs

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-11-15

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

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

International Nuclear Information System (INIS)

Brackbill, J.U.

1990-01-01

A particle-in-cell (PIC) method, FLIP is extended to magnetohydrodynamic (MHD) flow in two dimensions. Particles are used to reduce computational diffusion of the magnetic field. FLIP is an extension of ''classical'' PIC, where particles have mass, but every other property of the fluid is stored on a grid. In FLIP, particles have every property of the fluid, so that they provide a complete Lagrangian description not only to resolve contact discontinuities but also to reduce computational diffusion of linear and angular momentum. The interactions among the particles are calculated on a grid, for convenience and economy. The present study extends FLIP to MHD, by including information about the magnetic field among the attributes of the particles. 6 refs

MHD Program Plan, FY 1992

International Nuclear Information System (INIS)

1991-10-01

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

MHD stability calculations of high-β quasi-axisymmetric stellarators

International Nuclear Information System (INIS)

Fu, G.Y.; Ku, L.P.; Pomphrey, N.; Redi, M.; Kessel, C.; Monticello, D.; Reiman, A.; Hughes, M.; Cooper, W.A.; Nuehrenberg, C.

2001-01-01

The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size. (author)

MHD stability calculations of high-β quasi-axisymmetric stellarators

International Nuclear Information System (INIS)

Fu, G.Y.; Ku, L.P.; Pomphrey, N.; Redi, M.H.; Kessel, C.; Monticello, D.A.; Reiman, A.; Hughes, M.; Cooper, W.A.; Nuehrenberg, C.

1999-01-01

The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size. (author)

MHD Stability Calculations of High-Beta Quasi-Axisymmetric Stellarators

International Nuclear Information System (INIS)

Kessel, C.; Fu, G.Y.; Ku, L.P.; Redi, M.H.; Pomphrey, N.

1999-01-01

The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size

GASCON and MHDGAS: FORTRAN IV computer codes for calculating gas and condensed-phase compositions in the coal-fired open-cycle MHD system

Energy Technology Data Exchange (ETDEWEB)

Blackburn, P E

1977-12-01

Fortran IV computer codes have been written to calculate the equilibrium partial pressures of the gaseous phase and the quantity and composition of the condensed phases in the open-cycle MHD system. The codes are based on temperature-dependent equilibrium constants, mass conservation, the mass action law, and assumed ideal solution of compounds in each of two condensed phases. It is assumed that the phases are an oxide-silicate phase and a sulfate-carbonate-hydroxide phase. Calculations are iterated for gas and condensate concentrations while increasing or decreasing the total moles of elements, but keeping mole ratios constant, to achieve the desired total pressure. During iteration the oxygen partial pressure is incrementally changed. The decision to increase or decrease the oxygen pressure in this process depends on comparison of the oxygen content calculated in the gas and condensate phases with the initial amount of oxygen in the ash, coal, seed, and air. This process, together with a normalization step, allows the elements to converge to their initial quantities. Two versions of the computer code have been written. GASCON calculates the equilibrium gas partial pressures and the quantity and composition of the condensed phases in steps of thirteen temperature and pressure combinations in which the condensate is removed after each step, simulating continuous slag removal from the MHD system. MHDGAS retains the condensate for each step, simulating flow of condensate (and gas) through the MHD system.

2-D skin-current toroidal-MHD-equilibrium code

International Nuclear Information System (INIS)

Feinberg, B.; Niland, R.A.; Coonrod, J.; Levine, M.A.

1982-09-01

A two-dimensional, toroidal, ideal MHD skin-current equilibrium computer code is described. The code is suitable for interactive implementation on a minicomptuer. Some examples of the use of the code for design and interpretation of toroidal cusp experiments are presented

Real-time simulation of MHD/steam power plants by digital parallel processors

International Nuclear Information System (INIS)

Johnson, R.M.; Rudberg, D.A.

1981-01-01

Attention is given to a large FORTRAN coded program which simulates the dynamic response of the MHD/steam plant on either a SEL 32/55 or VAX 11/780 computer. The code realizes a detailed first-principle model of the plant. Quite recently, in addition to the VAX 11/780, an AD-10 has been installed for usage as a real-time simulation facility. The parallel processor AD-10 is capable of simulating the MHD/steam plant at several times real-time rates. This is desirable in order to develop rapidly a large data base of varied plant operating conditions. The combined-cycle MHD/steam plant model is discussed, taking into account a number of disadvantages. The disadvantages can be overcome with the aid of an array processor used as an adjunct to the unit processor. The conversion of some computations for real-time simulation is considered

Stability analysis of resistive MHD modes via a new numerical matching technique

International Nuclear Information System (INIS)

Furukawa, M.; Tokuda, S.; Zheng, L.-J.

2009-01-01

Full text: Asymptotic matching technique is one of the principal methods for calculating linear stability of resistive magnetohydrodynamics (MHD) modes such as tearing modes. In applying the asymptotic method, the plasma region is divided into two regions: a thin inner layer around the mode-resonant surface and ideal MHD regions except for the layer. If we try to solve this asymptotic matching problem numerically, we meet practical difficulties. Firstly, the inertia-less ideal MHD equation or the Newcomb equation has a regular singular point at the mode-resonant surface, leading to the so-called big and small solutions. Since the big solution is not square-integrable, it needs sophisticated treatment. Even if such a treatment is applied, the matching data or the ratio of small solution to the big one, has been revealed to be sensitive to local MHD equilibrium accuracy and grid structure at the mode-resonant surface by numerical experiments. Secondly, one of the independent solutions in the inner layer, which should be matched onto the ideal MHD solution, is not square-integrable. The response formalism has been adopted to resolve this problem. In the present paper, we propose a new method for computing the linear stability of resistive MHD modes via matching technique, where the plasma region is divided into ideal MHD regions and an inner region with finite width. The matching technique using an inner region with finite width was recently developed for ideal MHD modes in cylindrical geometry, and good performance was shown. Our method extends this idea to resistive MHD modes. In the inner region, the low-beta reduced MHD equations are solved, and the solution is matched onto the solution of the Newcomb equation by using boundary conditions such that the parallel electric field vanishes properly as approaching the computational boundaries. If we use the inner region with finite width, the practical difficulties raised above can be avoided from the beginning. Figure

MHD channel performance for potential early commercial MHD power plants

International Nuclear Information System (INIS)

Swallom, D.W.

1981-01-01

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

CASTOR: Normal-mode analysis of resistive MHD plasmas

NARCIS (Netherlands)

Kerner, W.; Goedbloed, J. P.; Huysmans, G. T. A.; Poedts, S.; Schwarz, E.

1998-01-01

The CASTOR (complex Alfven spectrum of toroidal plasmas) code computes the entire spectrum of normal-modes in resistive MHD for general tokamak configurations. The applied Galerkin method, in conjunction with a Fourier finite-element discretisation, leads to a large scale eigenvalue problem A (x)

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

International Nuclear Information System (INIS)

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

1996-01-01

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

MHD pilot industrial applications

International Nuclear Information System (INIS)

Freeman, M.; Riviere-Wekstein, G.

1994-01-01

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

Two-dimensional simulation of the MHD stability, (1)

International Nuclear Information System (INIS)

Kurita, Gen-ichi; Amano, Tsuneo.

1976-03-01

The two-dimensional computer code has been prepared to study MHD stability of an axisymmetric toroidal plasma with and without the surrounding vacuum region. It also includes the effect of magnetic surfaces with non-circular cross sections. The linearized equations of motion are solved as an initial value problem. The results by computer simulation are compared with those by the theory for the cylindrical plasma; they are in good agreement. (auth.)

Diagnostic development and support of MHD test facilities: Technical progress report for the period January, February, March 1985

International Nuclear Information System (INIS)

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

1985-04-01

Mississippi State University is developing diagnostic instruments for MHD power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for 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. Additionally, technical support of the diagnostic needs of the national MHD research effort is being provided

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

International Nuclear Information System (INIS)

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

1997-01-01

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

A Riccati solution for the ideal MHD plasma response with applications to real-time stability control

Science.gov (United States)

Glasser, Alexander; Kolemen, Egemen; Glasser, A. H.

2018-03-01

Active feedback control of ideal MHD stability in a tokamak requires rapid plasma stability analysis. Toward this end, we reformulate the δW stability method with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the generic tokamak ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD matrix Riccati differential equation. Since Riccati equations are prevalent in the control theory literature, such a shift in perspective brings to bear a range of numerical methods that are well-suited to the robust, fast solution of control problems. We discuss the usefulness of Riccati techniques in solving the stiff ordinary differential equations often encountered in ideal MHD stability analyses—for example, in tokamak edge and stellarator physics. We demonstrate the applicability of such methods to an existing 2D ideal MHD stability code—DCON [A. H. Glasser, Phys. Plasmas 23, 072505 (2016)]—enabling its parallel operation in near real-time, with wall-clock time ≪1 s . Such speed may help enable active feedback ideal MHD stability control, especially in tokamak plasmas whose ideal MHD equilibria evolve with inductive timescale τ≳ 1s—as in ITER.

Study on closed cycle MHD generation systems; Closed cycle MHD hatsuden system no kento

Energy Technology Data Exchange (ETDEWEB)

NONE

1988-03-01

The closed cycle noble gas MHD generation systems are surveyed and studied. The concept of closed cycle noble gas MHD generation is confirmed to extract high enthalpy, and now going into the engineering demonstration stage from the basic research stage. These systems have various characteristics. The highest working temperature is around 1,700 degrees C, which is close to that associated with the existing techniques. Use of helium or argon gas as the working fluid makes the system relatively free of various problems, e.g., corrosion. It can attain a much higher efficiency than the combined cycle involving gas turbine. It suffers less heat loss in the passages, is suitable for small- to medium-capacity power generation systems, and copes with varying load. The compact power generation passages decrease required size of the superconducting magnet. The technical problems to be solved include optimization of power generation conditions, demonstration of durability of the power generation passages, injection/recovery of the seed material, treatment of the working gas to remove molecular impurities, and development of heat exchangers serviceable at high temperature produced by direct combustion of coal. The conceptual designs of the triple combined system are completed. (NEDO)

Compact torus theory: MHD equilibrium and stability

International Nuclear Information System (INIS)

Barnes, D.C.; Seyler, C.E.; Anderson, D.V.

1979-01-01

Field reversed theta pinches have demonstrated the production and confinement of compact toroidal configurations with surprisingly good MHD stability. In these observations, the plasma is either lost by diffusion or by the loss of the applied field or is disrupted by an n = 2 (where n is the toroidal mode number) rotating instability only after 30 to 100 MHD times, when the configuration begins to rotate rigidly above a critical speed. These experiments have led one to investigate the equilibrium, stability, and rotation of a very elongated, toroidally axisymmetric configuration with no toroidal field. Many of the above observations are explained by recent results of these investigations which are summarized

Simulation of the MHD stabilities of the experiment on HL-2A tokamak by GATO code

International Nuclear Information System (INIS)

Pan Wei; Chen Liaoyuan; Dong Jiaqi; Shen Yong; Zhang Jinhua

2009-01-01

The ideal two-dimensional MHD stabilities code, GATO, has been successfully immigrated to the high-performance computing system of HL-2A and used to the simulation study of the ideal MHD stabilities of the plasmas produced by one of the pellets injection experiments on HL-2A tokamak. The EFIT code was used to reconstruct the equilibrium configures firstly and the GATO was used to compute their MHD stabilities secondly whose source data were obtained by the NO.4050 discharge of the experiments on HL-2A, and finally by analyzing these results the preliminary conclusion was devised that the confinement performance of the plasma was improved because of the stabilization effect of the anti-sheared configures created by the pellets injection. (authors)

A kinetic-MHD model for low frequency phenomena

International Nuclear Information System (INIS)

Cheng, C.Z.

1991-07-01

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

MHD Generating system

Science.gov (United States)

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

1980-01-01

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

Characteristics of laminar MHD fluid hammer in pipe

International Nuclear Information System (INIS)

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

2016-01-01

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

MHD (Magnetohydrodynamics) recovery and regeneration

Energy Technology Data Exchange (ETDEWEB)

McIlroy, R. A. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Probert, P. B. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Lahoda, E. J. [Westinghouse Electric Corp., Pittsburgh, PA (United States); Swift, W. M. [Argonne National Lab. (ANL), Argonne, IL (United States); Jackson, D. M. [Univ. of Tennessee Space Inst. (UTSI), Tullahoma, TN (United States); Prasad, J. [Univ. of Tennessee Space Inst. (UTSI), Tullahoma, TN (United States); Martin, J. [Hudson Engineering (United States); Rogers, C. [Hudson Engineering (United States); Ho, K. K. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Senary, M. K. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Lee, S. [Univ. of Akron, OH (United States)

1988-10-01

A two-phase program investigating MHD seed regeneration is described. In Phase I, bench scale experiments were carried out to demonstrate the technical feasibility of a proposed Seed Regeneration Process. The Phase I data has been used for the preliminary design of a Proof-of-Concept (POC) plant which will be built and tested in Phase II. The Phase I data will also be used to estimate the costs of a 300 Mw(t) demonstration plant for comparison with other processes. The Seed Regeneration Process consists of two major subprocesses; a Westinghouse Dry Reduction process and a modified Tampella (sulfur) Recovery process. The Westinghouse process reduces the recovered spent seed (i.e., potassium sulfate) to potassium polysulfide in a rotary kiln. The reduction product is dissolved in water to form green liquor, clarified to remove residual coal ash, and sent to the Tampella sulfur release system. The sulfur is released using carbon dioxide from flue gas in a two stage reaction. The sulfur is converted to elemental sulfur as a marketable by product. The potassium is crystallized from the green liquor and dried to the anhydrous form for return to the MHD unit.

MHD simulations on an unstructured mesh

International Nuclear Information System (INIS)

Strauss, H.R.; Park, W.; Belova, E.; Fu, G.Y.; Sugiyama, L.E.

1998-01-01

Two reasons for using an unstructured computational mesh are adaptivity, and alignment with arbitrarily shaped boundaries. Two codes which use finite element discretization on an unstructured mesh are described. FEM3D solves 2D and 3D RMHD using an adaptive grid. MH3D++, which incorporates methods of FEM3D into the MH3D generalized MHD code, can be used with shaped boundaries, which might be 3D

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1970-07-01

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

Estimating a planetary magnetic field with time-dependent global MHD simulations using an adjoint approach

Directory of Open Access Journals (Sweden)

C. Nabert

2017-05-01

Full Text Available The interaction of the solar wind with a planetary magnetic field causes electrical currents that modify the magnetic field distribution around the planet. We present an approach to estimating the planetary magnetic field from in situ spacecraft data using a magnetohydrodynamic (MHD simulation approach. The method is developed with respect to the upcoming BepiColombo mission to planet Mercury aimed at determining the planet's magnetic field and its interior electrical conductivity distribution. In contrast to the widely used empirical models, global MHD simulations allow the calculation of the strongly time-dependent interaction process of the solar wind with the planet. As a first approach, we use a simple MHD simulation code that includes time-dependent solar wind and magnetic field parameters. The planetary parameters are estimated by minimizing the misfit of spacecraft data and simulation results with a gradient-based optimization. As the calculation of gradients with respect to many parameters is usually very time-consuming, we investigate the application of an adjoint MHD model. This adjoint MHD model is generated by an automatic differentiation tool to compute the gradients efficiently. The computational cost for determining the gradient with an adjoint approach is nearly independent of the number of parameters. Our method is validated by application to THEMIS (Time History of Events and Macroscale Interactions during Substorms magnetosheath data to estimate Earth's dipole moment.

Acceleration of the OpenFOAM-based MHD solver using graphics processing units

International Nuclear Information System (INIS)

He, Qingyun; Chen, Hongli; Feng, Jingchao

2015-01-01

Highlights: • A 3D PISO-MHD was implemented on Kepler-class graphics processing units (GPUs) using CUDA technology. • A consistent and conservative scheme is used in the code which was validated by three basic benchmarks in a rectangular and round ducts. • Parallelized of CPU and GPU acceleration were compared relating to single core CPU in MHD problems and non-MHD problems. • Different preconditions for solving MHD solver were compared and the results showed that AMG method is better for calculations. - Abstract: The pressure-implicit with splitting of operators (PISO) magnetohydrodynamics MHD solver of the couple of Navier–Stokes equations and Maxwell equations was implemented on Kepler-class graphics processing units (GPUs) using the CUDA technology. The solver is developed on open source code OpenFOAM based on consistent and conservative scheme which is suitable for simulating MHD flow under strong magnetic field in fusion liquid metal blanket with structured or unstructured mesh. We verified the validity of the implementation on several standard cases including the benchmark I of Shercliff and Hunt's cases, benchmark II of fully developed circular pipe MHD flow cases and benchmark III of KIT experimental case. Computational performance of the GPU implementation was examined by comparing its double precision run times with those of essentially the same algorithms and meshes. The resulted showed that a GPU (GTX 770) can outperform a server-class 4-core, 8-thread CPU (Intel Core i7-4770k) by a factor of 2 at least.

Acceleration of the OpenFOAM-based MHD solver using graphics processing units

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-15

Highlights: • A 3D PISO-MHD was implemented on Kepler-class graphics processing units (GPUs) using CUDA technology. • A consistent and conservative scheme is used in the code which was validated by three basic benchmarks in a rectangular and round ducts. • Parallelized of CPU and GPU acceleration were compared relating to single core CPU in MHD problems and non-MHD problems. • Different preconditions for solving MHD solver were compared and the results showed that AMG method is better for calculations. - Abstract: The pressure-implicit with splitting of operators (PISO) magnetohydrodynamics MHD solver of the couple of Navier–Stokes equations and Maxwell equations was implemented on Kepler-class graphics processing units (GPUs) using the CUDA technology. The solver is developed on open source code OpenFOAM based on consistent and conservative scheme which is suitable for simulating MHD flow under strong magnetic field in fusion liquid metal blanket with structured or unstructured mesh. We verified the validity of the implementation on several standard cases including the benchmark I of Shercliff and Hunt's cases, benchmark II of fully developed circular pipe MHD flow cases and benchmark III of KIT experimental case. Computational performance of the GPU implementation was examined by comparing its double precision run times with those of essentially the same algorithms and meshes. The resulted showed that a GPU (GTX 770) can outperform a server-class 4-core, 8-thread CPU (Intel Core i7-4770k) by a factor of 2 at least.

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

International Nuclear Information System (INIS)

Ishizawa, Akihiro; Nakajima, Noriyoshi

2007-01-01

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

Surface currents on the plasma-vacuum interface in MHD equilibria

Science.gov (United States)

Hanson, James

2017-10-01

The VMEC non-axisymmetric MHD equilibrium code can compute free-boundary equilibria. Since VMEC assumes that magnetic fields within the plasma form closed and nested flux surfaces, the plasma-vacuum interface is a flux surface, and the total magnetic field there has no normal component. VMEC imposes this condition of zero normal field using the potential formulation of Merkel, and solves a Neumann problem for the magnetic potential in the exterior region. This boundary condition necessarily admits the possibility of a surface current on the interface. While this surface current may be small in MHD equilibrium, it is readily computed in terms of the magnetic potentials in both the interior and exterior regions, evaluated on the surface. If only the external magnetic potential is known (as in VMEC), then the surface current can be computed from the discontinuity of the tangential field across the interface. Examples of the surface current for VMEC equilibria will be shown for a zero-pressure stellarator equilibrium. Field-line following of the vacuum magnetic field shows magnetic islands within the plasma region.

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

International Nuclear Information System (INIS)

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

1979-04-01

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

Advanced energy utilization MHD power generation

International Nuclear Information System (INIS)

2008-01-01

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

MHD simulations of DC helicity injection for current drive in tokamaks

International Nuclear Information System (INIS)

Sovinec, C.R.; Prager, S.C.

1994-12-01

MHD computations of DC helicity injection in tokamak-like configurations show current drive with no ''loop voltage'' in a resistive, pressureless plasma. The self-consistently generated current profiles are unstable to resistive modes that partially relax the profile through the MHD dynamo mechanism. The current driven by the fluctuations leads to closed contours of average poloidal flux. However, the 1% fluctuation level is large enough to produce a region of stochastic magnetic field. A limited Lundquist number (S) scan from 2.5 x 10 3 to 4 x 10 4 indicates that both the fluctuation level and relaxation increase with S

Principal characteristics of SFC type MHD generator

International Nuclear Information System (INIS)

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

1988-01-01

This paper describes the experimental and analytical results obtained for an MHD channel with a two dimensionally shaped magnetic field configuration called 'the SFC-type'. The power generating performance was examined under various load conditions and B-field intensities with a 2 MWt shock tunnel MHD facility. It is demonstrated that the power output performance and the enthalpy extraction scaling law of the conventional uniform B-field MHD generator (UFC-type) were significantly improved by the SFC-design of the spatial distribution of the magnetic field. The arcing processes were also examined by a high speed camera and the post-test observation of arc spot traces on electrodes. Further, the characteristic frequencies of each of the so-called micro and constricted arcs were clarified by spectral analyses. The critical current densities, which define the transient conditions of each from the diffuse-to micro arc, and from the micro-to constricted arc modes could be clearly obtained by the present spectral analysis method. We also investigated the three-dimensional behavior under strong magnetic field based on the coupled electrical and hydrodynamical equations for both of the middle scale SFC-and UFC-type generators. Finally, it is concluded from the above mentioned various aspects that the shaped 2-D magnetic field design will offer a most useful means for the realization of a compact, high efficiency and a long duration open-cycle MHD generator. (author)

Ceramics and M.H.D

International Nuclear Information System (INIS)

Yvars, M.

1979-10-01

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

Technical surveys on MHD combustors. Surveys on incorporation of pressurized coal partial combustion furnaces; MHD combustor gijutsu chosa. Kaatsugata sekitan bubun nenshoro no donyu chosa

Energy Technology Data Exchange (ETDEWEB)

NONE

1991-03-01

The pressurized coal partial combustion (PCPC) furnace is surveyed/studied for its incorporation in MHD generation. The technical development of the atmospheric CPC has been basically completed, and the concept is demonstrated using a test system of commercial size. Many techniques developed for the atmospheric CPC are applicable to the PCPC system. These include structures of the CPC furnace walls, and slag handling and simulation techniques. Combination of PFBC with PCPC or IGCC can bring about many merits, e.g., enhanced efficiency and abated NOx emissions for the combined cycle power generation. These topping cycles, therefore, should be developed in the early stage. MHD power generation is one of the concepts that can enhance efficiency. In particular, the techniques for closed cycle MHD generation have notably advanced recently. The PCPC techniques are useful for coal combustors for MHD generation. Full-scale development works for the direct coal combustion gas turbine systems have been just started for the IGCC systems of the next generation, and the PCPC-related techniques are expected to serve as the central techniques for these turbine systems. (NEDO)

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

Science.gov (United States)

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

MHD instabilities in heliotron/torsatron

International Nuclear Information System (INIS)

Wakatani, Masahiro; Nakamura, Yuji; Ichiguchi, Katsuji

1992-01-01

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

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

Science.gov (United States)

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

Linear ideal MHD stability calculations for ITER

International Nuclear Information System (INIS)

Hogan, J.T.

1988-01-01

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

Investigations on application of multigrid method to MHD equilibrium analysis

International Nuclear Information System (INIS)

Ikuno, Soichiro

2000-01-01

The potentiality of application for Multi-grid method to MHD equilibrium analysis is investigated. The nonlinear eigenvalue problem often appears when the MHD equilibria are determined by solving the Grad-Shafranov equation numerically. After linearization of the equation, the problem is solved by use of the iterative method. Although the Red-Black SOR method or Gauss-Seidel method is often used for the solution of the linearized equation, it takes much CPU time to solve the problem. The Multi-grid method is compared with the SOR method for the Poisson Problem. The results of computations show that the CPU time required for the Multi-grid method is about 1000 times as small as that for the SOR method. (author)

Inclusion of pressure and flow in the KITES MHD equilibrium code

International Nuclear Information System (INIS)

Raburn, Daniel; Fukuyama, Atsushi

2013-01-01

One of the simplest self-consistent models of a plasma is single-fluid magnetohydrodynamic (MHD) equilibrium with no bulk fluid flow under axisymmetry. However, both fluid flow and non-axisymmetric effects can significantly impact plasma equilibrium and confinement properties: in particular, fluid flow can produce profile pedestals, and non-axisymmetric effects can produce islands and stochastic regions. There exist a number of computational codes which are capable of calculating equilibria with arbitrary flow or with non-axisymmetric effects. Previously, a concept for a code to calculate MHD equilibria with flow in non-axisymmetric systems was presented, called the KITES (Kyoto ITerative Equilibrium Solver) code. Since then, many of the computational modules for the KITES code have been completed, and the work-in-progress KITES code has been used to calculate non-axisymmetric force-free equilibria. Additional computational modules are required to allow the KITES code to calculate equilibria with pressure and flow. Here, the authors report on the approaches used in developing these modules and provide a sample calculation with pressure. (author)

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1969-07-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1990-07-01

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

Superconducting dipole magnet for the UTSI MHD facility

International Nuclear Information System (INIS)

Wang, S.T.; Niemann, R.C.; Turner, L.R.

1978-01-01

The Argonne National Laboratory is designing and will build a large superconducting dipole magnet system for use in the Coal Fired Flow MHD Research Facility at the University of Tennessee Space Institute (UTSI). Presented in detail are the conceptual design of the magnet geometry, conductor design, cryostability evaluation, magnetic pressure computation, structural design, cryostat design, the cryogenics system design, and magnet instrumentations and control

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-03-01

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

The on-line data acquisition system for the MHD facility of Frascati

International Nuclear Information System (INIS)

Di Bartolomeo, M.; Papalia, B.; Gay, P.; Panaccione, L.

1975-01-01

An on-line data acquisition system for the MHD facility of the Laboratorio Conversione Diretta at Frascati is described. After a brief description of the MHD facility and of the measurement requirements, the criteria a,d the configuration of the minicomputer-based data acquisition system chosen are presented. Then the general philosophy and the flow-charts of the software implemented are shown, with particular emphasis to the real-time requirements of the measurement system. At last it is illustrated an off-line program, running on a large computer, that elaborates the output data of the data acquisition system

MHD saga in the gases

International Nuclear Information System (INIS)

Petit, J.P.

1995-01-01

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

Generation of compressible modes in MHD turbulence

Energy Technology Data Exchange (ETDEWEB)

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

2005-05-01

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

Liquid metal MHD research and development in Israel

International Nuclear Information System (INIS)

Branover, H.

1993-01-01

The study of liquid metal MHD in Israel commenced in 1973. Initially it was concentrated mainly on laminar flows influenced by external magnetic fields. In 1978 a liquid metal MHD energy conversion program was started. This program was developed at the Center for MHD Studies at Ben-Gurion University in Beer-Sheva, with the participation of specialists from the Technion, the Hebrew University of Jerusalem, Israel Atomic Energy Commission, and others. The program was sponsored initially by the Israel Ministry of Energy and Infrastructure, and later by the Ministry of Industry and Trade. Since 1980, Solmecs, a private commercial company has become a major factor in the development of liquid metal MHD in Israel. From the very beginning the program was based on broad international cooperation. A number of overseas institutions and individuals became participants in the program. Through extensive research and evaluation of a number of concepts of liquid metal MHD power generation systems, It was established that the most promising concept, demanding a relatively short period of development, is the gravitational system using heavy metals (lead, lead alloys) as the magneto-hydrodynamic fluid and steam or gases as thermodynamic fluids. This concept was chosen for further development and industrial application, and the program related to such systems was named the Etgar Program. The main directions of research and development activities have been defined as follows: investigations of physical phenomena, development of universal numerical code for parametric studies, optimization and design of the system, material studies, development of engineering components, building and testing of integrated small-scale Etgar type systems, economic evaluation of the system and comparison with conventional technologies, development of moderate scale industrial demonstration plant. At this time 6 items have been fully implemented and activities on the last item were started. (author)

Ultrahigh temperature vapor core reactor-MHD system for space nuclear electric power

Science.gov (United States)

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.

HPC parallel programming model for gyrokinetic MHD simulation

International Nuclear Information System (INIS)

Naitou, Hiroshi; Yamada, Yusuke; Tokuda, Shinji; Ishii, Yasutomo; Yagi, Masatoshi

2011-01-01

The 3-dimensional gyrokinetic PIC (particle-in-cell) code for MHD simulation, Gpic-MHD, was installed on SR16000 (“Plasma Simulator”), which is a scalar cluster system consisting of 8,192 logical cores. The Gpic-MHD code advances particle and field quantities in time. In order to distribute calculations over large number of logical cores, the total simulation domain in cylindrical geometry was broken up into N DD-r × N DD-z (number of radial decomposition times number of axial decomposition) small domains including approximately the same number of particles. The axial direction was uniformly decomposed, while the radial direction was non-uniformly decomposed. N RP replicas (copies) of each decomposed domain were used (“particle decomposition”). The hybrid parallelization model of multi-threads and multi-processes was employed: threads were parallelized by the auto-parallelization and N DD-r × N DD-z × N RP processes were parallelized by MPI (message-passing interface). The parallelization performance of Gpic-MHD was investigated for the medium size system of N r × N θ × N z = 1025 × 128 × 128 mesh with 4.196 or 8.192 billion particles. The highest speed for the fixed number of logical cores was obtained for two threads, the maximum number of N DD-z , and optimum combination of N DD-r and N RP . The observed optimum speeds demonstrated good scaling up to 8,192 logical cores. (author)

Magnetic levitation and MHD propulsion

International Nuclear Information System (INIS)

Tixador, P.

1994-01-01

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

Magnetic levitation and MHD propulsion

Energy Technology Data Exchange (ETDEWEB)

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

1994-04-01

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

Generalized reduced MHD equations

International Nuclear Information System (INIS)

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

1998-07-01

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

MHD stability, operational limits and disruptions

International Nuclear Information System (INIS)

1999-01-01

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

Extended MHD modeling of nonlinear instabilities in fusion and space plasmas

Energy Technology Data Exchange (ETDEWEB)

Germaschewski, Kai [Univ. of New Hampshire, Durham, NH (United States)

2017-11-15

A number of different sub-projects where pursued within this DOE early career project. The primary focus was on using fully nonlinear, curvilinear, extended MHD simulations of instabilities with applications to fusion and space plasmas. In particular, we performed comprehensive studies of the dynamics of the double tearing mode in different regimes and confi gurations, using Cartesian and cyclindrical geometry and investigating both linear and non-linear dynamics. In addition to traditional extended MHD involving Hall term and electron pressure gradient, we also employed a new multi-fluid moment model, which shows great promise to incorporate kinetic effects, in particular off-diagonal elements of the pressure tensor, in a fluid model, which is naturally computationally much cheaper than fully kinetic particle or Vlasov simulations. We used our Vlasov code for detailed studies of how weak collisions effect plasma echos. In addition, we have played an important supporting role working with the PPPL theory group around Will Fox and Amitava Bhattacharjee on providing simulation support for HED plasma experiments performed at high-powered laser facilities like OMEGA-EP in Rochester, NY. This project has support a great number of computational advances in our fluid and kinetic plasma models, and has been crucial to winning multiple INCITE computer time awards that supported our computational modeling.

MHD power generation for the synthetic-fuels industry

International Nuclear Information System (INIS)

Jones, M.S. Jr.

1982-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-03-01

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

Boundary effects on the MHD dynamo in laboratory plasmas

International Nuclear Information System (INIS)

Ho, Y.L.; Prager, S.C.

1989-07-01

In recent laboratory experiments, a dynamo-like mechanism has been demonstrated in which a portion of the axisymmetric component of the magnetic field is believed to be sustained by 3D spatial fluctuations in the field and flow. With a conducting shell at the plasma surface, past MHD computation shows that sustainment arises from fluctuations which cause magnetic reconnection. If the conducting wall is retracted from the plasma surface, the fluctuations are amplified and the dynamo sustainment is still active for the times studied, but an increased energy input to the plasma is required through the applied electric field. The retraction of the conducting wall enhances the helicity dissipation rate by the intersection of the fields with the resistive surface which bounds the plasma. This enhanced helicity dissipation is balanced by the helicity injection that accompanies the increased applied electric field. 17 refs., 7 figs., 1 tab

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

International Nuclear Information System (INIS)

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

1990-01-01

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

Substorm effects in MHD and test particle simulations of magnetotail dynamics

International Nuclear Information System (INIS)

Birn, J.; Hesse, M.

1998-01-01

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

Technical support for open-cycle MHD program

Energy Technology Data Exchange (ETDEWEB)

None

1978-05-01

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

NaK-nitrogen liquid metal MHD converter tests at 30 kw

Science.gov (United States)

Cerini, D. J.

1974-01-01

The feasibility of electrical power generation with an ambient temperature liquid-metal MHD separator cycle is demonstrated by tests in which a NaK-nitrogen LM-MHD converter was operated at nozzle inlet pressures ranging from 100 to 165 N/sq cm, NaK flow rates from 46 to 72 kg/sec, and nitrogen flow rates from 2.4 to 3.8 kg/sec. The generator was operated as an eight-phase linear induction generator, with two of the eight phases providing magnetic field compensation to minimized electrical end losses at the generator channel inlet and exit.

Neoclassical MHD descriptions of tokamak plasmas

International Nuclear Information System (INIS)

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

1988-01-01

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

Ideal MHD stability analysis of KSTAR target AT mode

International Nuclear Information System (INIS)

Yi, S.M.; Kim, J.H.; You, K.I.; Kim, J.Y.

2009-01-01

Full text: A main research objective of KSTAR (Korea Superconducting Tokamak Advanced Research) device is to demonstrate the steady-state operation capability of high-performance AT (Advanced Tokamak) mode. To meet this goal, it is critical for KSTAR to have a good MHD stability boundary, particularly against the high-beta ideal instabilities such as the external kink and the ballooning modes. To support this MHD stability KSTAR has been designed to have a strong plasma shape and a close interval between plasma and passive- plate wall. During the conceptual design phase of KSTAR, a preliminary study was performed to estimate the high beta MHD stability limit of KSTAR target AT mode using PEST and VACUUM codes and it was shown that the target AT mode can be stable up to β N ∼ 5 with a well-defined plasma pressure and current profiles. Recently, a new calculation has been performed to estimate the ideal stability limit in various KSTAR operating conditions using DCON code, and it has been observed that there is some difference between the new and old calculation results, particularly in the dependence of the maximum β N value on the toroidal mode number. Here, we thus present a more detailed analysis of the ideal MHD stability limit of KSTAR target AT mode using various codes, which include GATO as well as PEST and DCON, in the comparison of calculation results among the three codes. (author)

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

International Nuclear Information System (INIS)

Huysmans, G.

1998-03-01

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

Computational studies of tokamak plasmas

International Nuclear Information System (INIS)

Takizuka, Tomonori; Tsunematsu, Toshihide; Tokuda, Shinji

1981-02-01

Computational studies of tokamak plasmas are extensively advanced. Many computational codes have been developed by using several kinds of models, i.e., the finite element formulation of MHD equations, the time dependent multidimensional fluid model, and the particle model with the Monte-Carlo method. These codes are applied to the analyses of the equilibrium of an axisymmetric toroidal plasma (SELENE), the time evolution of the high-beta tokamak plasma (APOLLO), the low-n MHD stability (ERATO-J) and high-n ballooning mode stability (BOREAS) in the INTOR tokamak, the nonlinear MHD stability, such as the positional instability (AEOLUS-P), resistive internal mode (AEOLUS-I) etc., and the divertor functions. (author)

Integration of Extended MHD and Kinetic Effects in Global Magnetosphere Models

Science.gov (United States)

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

2015-12-01

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

Feasibility study of a nonequilibrium MHD accelerator concept for hypersonic propulsion ground testing

International Nuclear Information System (INIS)

Lee, Ying-Ming; Simmons, G.A.; Nelson, G.L.

1995-01-01

A National Aeronautics and Space Administration (NASA) funded research study to evaluate the feasibility of using magnetohydrodynamic (MHD) body force accelerators to produce true air simulation for hypersonic propulsion ground testing is discussed in this paper. Testing over the airbreathing portion of a transatmospheric vehicle (TAV) hypersonic flight regime will require high quality air simulation for actual flight conditions behind a bow shock wave (forebody, pre-inlet region) for flight velocities up to Mach 16 and perhaps beyond. Material limits and chemical dissociation at high temperature limit the simulated flight Mach numbers in conventional facilities to less than Mach 12 for continuous and semi-continuous testing and less than Mach 7 for applications requiring true air chemistry. By adding kinetic energy directly to the flow, MHD accelerators avoid the high temperatures and pressures required in the reservoir region of conventional expansion facilities, allowing MHD to produce true flight conditions in flight regimes impossible with conventional facilities. The present study is intended to resolve some of the critical technical issues related to the operation of MHD at high pressure. Funding has been provided only for the first phase of a three to four year feasibility study that would culminate in the demonstration of MHD acceleration under conditions required to produce true flight conditions behind a bow shock wave to flight Mach numbers of 16 or greater. MHD critical issues and a program plan to resolve these are discussed

Overview of liquid-metal MHD

International Nuclear Information System (INIS)

Dunn, P.F.

1978-01-01

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

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

International Nuclear Information System (INIS)

1968-01-01

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

Modeling of flow-dominated MHD instabilities at WiPPAL using NIMROD

Science.gov (United States)

Flanagan, K.; McCollam, K. J.; Milhone, J.; Mirnov, V. V.; Nornberg, M. D.; Peterson, E. E.; Siller, R.; Forest, C. B.

2017-10-01

Using the NIMROD (non-ideal MHD with rotation - open discussion) code developed at UW-Madison, we model two different flow scenarios to study the onset of MHD instabilities in flow-dominated plasmas in the Big Red Ball (BRB) and the Plasma Couette Experiment (PCX). Both flows rely on volumetric current drive, where a large current is drawn through the plasma across a weak magnetic field, injecting J × B torque across the whole volume. The first scenario uses a vertical applied magnetic field and a mostly radial injected current to create Couette-like flows which may excite the magnetorotational instability (MRI). In the other scenario, a quadrupolar field is applied to create counter-rotating von Karman-like flow that demonstrates a dynamo-like instability. For both scenarios, the differences between Hall and MHD Ohm's laws are explored. The implementation of BRB geometry in NIMROD, details of the observed flows, and instability results are shown. This work was funded by DoE and NSF.

Scaling, Intermittency and Decay of MHD Turbulence

International Nuclear Information System (INIS)

Lazarian, A.; Cho, Jungyeon

2005-01-01

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

Neoclassical MHD equations for tokamaks

International Nuclear Information System (INIS)

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

1986-03-01

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

A nonlinear resistive MHD-code in cylindrical geometry

International Nuclear Information System (INIS)

Jakoby, A.

1987-11-01

A computer code has been developed which solves the full compressible resistive magnetohydrodynamic (MHD) equations in cylindrical geometry. The variables are expanded in Fourier series in the poloidal and axial directions while finite differences are used in the radial direction. The time advance is accomplished by using a semi-implicit predictor-corrector-scheme. Applications to the ideal m=1 ideal kink saturation in the nonlinear regime and the subsequent decay of the singular current layer due to resistivity are presented. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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.

Relativistic MHD simulations of stellar core collapse and magnetars

Energy Technology Data Exchange (ETDEWEB)

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

2011-02-01

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

Semi-implicit method for three-dimensional compressible MHD simulation

International Nuclear Information System (INIS)

Harned, D.S.; Kerner, W.

1984-03-01

A semi-implicit method for solving the full compressible MHD equations in three dimensions is presented. The method is unconditionally stable with respect to the fast compressional modes. The time step is instead limited by the slower shear Alfven motion. The computing time required for one time step is essentially the same as for explicit methods. Linear stability limits are derived and verified by three-dimensional tests on linear waves in slab geometry. (orig.)

Priority pollutant analysis of MHD-derived combustion products

Science.gov (United States)

Parks, Katherine D.

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

Prediction of transverse asymmetries in MHD ducts with zero net Hall current

International Nuclear Information System (INIS)

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

1981-01-01

A new class of fluid-electrical asymmetries in MHD generator channel flow are predicted. It is shown that the existence of interelectrode asymmetries is not confined to generators in which there exists a nonzero net axial current, but rather they are induced even in the case of the Faraday generators. Also demonstrated is the impact of these asymmetries upon the generator and diffuser flow. It is concluded that in MHD generators, the net axial current in the cross plane is identically zero, while at any given point in the plane, the local Hall current density is in general nonzero

MHD intermediate shock discontinuities: Pt. 1

International Nuclear Information System (INIS)

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

1989-01-01

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

Experimental rigs for MHD studies

International Nuclear Information System (INIS)

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

1976-01-01

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

Gasdynamic performance in relation to the power extraction of an MHD generator

International Nuclear Information System (INIS)

Massee, P.

1983-01-01

A study of the gasdynamical processes in MHD generators has been made both theoretically and experimentally. A core flow and boundary layer model has been developed. In order to obtain a fast computer code which can be used for engineering purposes the quasi-one-dimensional approximation is used. It is shown in this thesis that the boundary layers have to be calculated from integral equations describing momentum, kinetic energy and stagnation enthalpy respectively, when the MHD effects in the boundary layers are properly taken into account. Calculations with the developed core flow and boundary layer model have shown that the electrical power output is limited by the design of the existing facility and have indicated possibilities to circumvent this limitation. (Auth.)

MHD Integrated Topping Cycle Project

Energy Technology Data Exchange (ETDEWEB)

1992-01-01

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

Axisymmetric MHD stable sloshing ion distributions

International Nuclear Information System (INIS)

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

1986-07-01

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

Dynamics of nonlinear resonant slow MHD waves in twisted flux tubes

Directory of Open Access Journals (Sweden)

R. Erdélyi

2002-01-01

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

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

Science.gov (United States)

Chang, Zuoyang

1996-11-01

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

Investigations on high speed MHD liquid flow

International Nuclear Information System (INIS)

Yamasaki, Takasuke; Kamiyama, Shin-ichi.

1982-01-01

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

Preliminary results of MHD stability in HL-1 tokamak

International Nuclear Information System (INIS)

Zheng Yongzhen; Ma Tengcai; Xiao Zhenggui Cai Renfang

1987-01-01

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

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

International Nuclear Information System (INIS)

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

1978-01-01

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

Laser-Plasma Modeling Using PERSEUS Extended-MHD Simulation Code for HED Plasmas

Science.gov (United States)

Hamlin, Nathaniel; Seyler, Charles

2017-10-01

We discuss the use of the PERSEUS extended-MHD simulation code for high-energy-density (HED) plasmas in modeling the influence of Hall and electron inertial physics on laser-plasma interactions. By formulating the extended-MHD equations as a relaxation system in which the current is semi-implicitly time-advanced using the Generalized Ohm's Law, PERSEUS enables modeling of extended-MHD phenomena (Hall and electron inertial physics) without the need to resolve the smallest electron time scales, which would otherwise be computationally prohibitive in HED plasma simulations. We first consider a laser-produced plasma plume pinched by an applied magnetic field parallel to the laser axis in axisymmetric cylindrical geometry, forming a conical shock structure and a jet above the flow convergence. The Hall term produces low-density outer plasma, a helical field structure, flow rotation, and field-aligned current, rendering the shock structure dispersive. We then model a laser-foil interaction by explicitly driving the oscillating laser fields, and examine the essential physics governing the interaction. This work is supported by the National Nuclear Security Administration stewardship sciences academic program under Department of Energy cooperative agreements DE-FOA-0001153 and DE-NA0001836.

Astrophysics days and MHD

International Nuclear Information System (INIS)

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

2001-05-01

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

Problems in nonlinear resistive MHD

International Nuclear Information System (INIS)

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

1998-01-01

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

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

International Nuclear Information System (INIS)

Rietjens, L.H.

1972-04-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1981-01-01

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

MHD power plants - a reality of the 80's

International Nuclear Information System (INIS)

Pishchikov, S.

1981-01-01

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

MHD power plants - a reality of the 80's

Energy Technology Data Exchange (ETDEWEB)

Pishchikov, S

1981-02-01

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

Results from a large-scale MHD propulsion experiment

International Nuclear Information System (INIS)

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

1992-01-01

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

MHD Modeling of Conductors at Ultra-High Current Density

International Nuclear Information System (INIS)

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

2000-01-01

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

MHD Modeling of Conductors at Ultra-High Current Density

International Nuclear Information System (INIS)

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

1999-01-01

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

Global and kinetic MHD simulation by the Gpic-MHD code

International Nuclear Information System (INIS)

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

2011-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1982-03-01

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

Investigations of MHD activity in ASDEX discharges

International Nuclear Information System (INIS)

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

1984-06-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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)

Towards a Scalable Fully-Implicit Fully-coupled Resistive MHD Formulation with Stabilized FE Methods

Energy Technology Data Exchange (ETDEWEB)

Shadid, J N; Pawlowski, R P; Banks, J W; Chacon, L; Lin, P T; Tuminaro, R S

2009-06-03

This paper presents an initial study that is intended to explore the development of a scalable fully-implicit stabilized unstructured finite element (FE) capability for low-Mach-number resistive MHD. The discussion considers the development of the stabilized FE formulation and the underlying fully-coupled preconditioned Newton-Krylov nonlinear iterative solver. To enable robust, scalable and efficient solution of the large-scale sparse linear systems generated by the Newton linearization, fully-coupled algebraic multilevel preconditioners are employed. Verification results demonstrate the expected order-of-acuracy for the stabilized FE discretization of a 2D vector potential form for the steady and transient solution of the resistive MHD system. In addition, this study puts forth a set of challenging prototype problems that include the solution of an MHD Faraday conduction pump, a hydromagnetic Rayleigh-Bernard linear stability calculation, and a magnetic island coalescence problem. Initial results that explore the scaling of the solution methods are presented on up to 4096 processors for problems with up to 64M unknowns on a CrayXT3/4. Additionally, a large-scale proof-of-capability calculation for 1 billion unknowns for the MHD Faraday pump problem on 24,000 cores is presented.

Magnetic levitation and MHD propulsion

Science.gov (United States)

Tixador, P.

1994-04-01

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

PHYSICAL PERFORMANCE AND BODY COMPOSITION IN MAINTENANCE HEMODIALYSIS (MHD PATIENTS

Directory of Open Access Journals (Sweden)

M Zhang

2012-06-01

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

An MHD Dynamo Experiment.

Science.gov (United States)

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

1997-11-01

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

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

Science.gov (United States)

Buttery, Richard

2011-08-01

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

Radiation heat transfer within an open-cycle MHD generator channel

Science.gov (United States)

Delil, A. A. M.

1983-05-01

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

Neoclassical viscous stress tensor for non-linear MHD simulations with XTOR-2F

International Nuclear Information System (INIS)

Mellet, N.; Maget, P.; Meshcheriakov, D.; Lütjens, H.

2013-01-01

The neoclassical viscous stress tensor is implemented in the non-linear MHD code XTOR-2F (Lütjens and Luciani 2010 J. Comput. Phys. 229 8130–43), allowing consistent bi-fluid simulations of MHD modes, including the metastable branch of neoclassical tearing modes (NTMs) (Carrera et al 1986 Phys. Fluids 29 899–902). Equilibrium flows and bootstrap current from the neoclassical theory are formally recovered in this Chew–Goldberger–Low formulation. The non-linear behaviour of the new model is verified on a test case coming from a Tore Supra non-inductive discharge. A NTM threshold that is larger than with the previous model is obtained. This is due to the fact that the velocity is now part of the bootstrap current and that it differs from the theoretical neoclassical value. (paper)

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

Energy Technology Data Exchange (ETDEWEB)

None

1979-01-01

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

Demonstration of measurement-only blind quantum computing

Science.gov (United States)

Greganti, Chiara; Roehsner, Marie-Christine; Barz, Stefanie; Morimae, Tomoyuki; Walther, Philip

2016-01-01

Blind quantum computing allows for secure cloud networks of quasi-classical clients and a fully fledged quantum server. Recently, a new protocol has been proposed, which requires a client to perform only measurements. We demonstrate a proof-of-principle implementation of this measurement-only blind quantum computing, exploiting a photonic setup to generate four-qubit cluster states for computation and verification. Feasible technological requirements for the client and the device-independent blindness make this scheme very applicable for future secure quantum networks.

Method of operating a MHD power plant

International Nuclear Information System (INIS)

Wysk, S.R.

1982-01-01

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

Pseudo-MHD ballooning modes in tokamak plasmas

International Nuclear Information System (INIS)

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

1996-08-01

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

MHD/gas turbine systems designed for low cooling water requirements

International Nuclear Information System (INIS)

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

1983-01-01

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

Electric potential behaviour in segmented Faraday-type MHD generators

International Nuclear Information System (INIS)

James, M.I.; Mittal, M.L.; Gupta, G.P.; Rohatgi, V.K.

1985-01-01

The potential distribution in the transverse cross-section of a segmented Faraday-type MHD generator is studied. The governing elliptic equation, derived with allowance for the finite electrode segmentation effect and nonuniformity of the gas in the channel, is solved numerically using the Alternating Direction Implicit method in the finite difference scheme, instead of the successive over-relaxation method. The computed potential distribution and the potential drops are found to compare well with experimental results. The potential drops at the electrodes are found to increase with increasing current density. (author)

Demonstration of measurement-only blind quantum computing

International Nuclear Information System (INIS)

Greganti, Chiara; Roehsner, Marie-Christine; Barz, Stefanie; Walther, Philip; Morimae, Tomoyuki

2016-01-01

Blind quantum computing allows for secure cloud networks of quasi-classical clients and a fully fledged quantum server. Recently, a new protocol has been proposed, which requires a client to perform only measurements. We demonstrate a proof-of-principle implementation of this measurement-only blind quantum computing, exploiting a photonic setup to generate four-qubit cluster states for computation and verification. Feasible technological requirements for the client and the device-independent blindness make this scheme very applicable for future secure quantum networks. (paper)

PIXIE3D: An efficient, fully implicit, parallel, 3D extended MHD code for fusion plasma modeling

International Nuclear Information System (INIS)

Chacon, L.

2007-01-01

PIXIE3D is a modern, parallel, state-of-the-art extended MHD code that employs fully implicit methods for efficiency and accuracy. It features a general geometry formulation, and is therefore suitable for the study of many magnetic fusion configurations of interest. PIXIE3D advances the state of the art in extended MHD modeling in two fundamental ways. Firstly, it employs a novel conservative finite volume scheme which is remarkably robust and stable, and demands very small physical and/or numerical dissipation. This is a fundamental requirement when one wants to study fusion plasmas with realistic conductivities. Secondly, PIXIE3D features fully-implicit time stepping, employing Newton-Krylov methods for inverting the associated nonlinear systems. These methods have been shown to be scalable and efficient when preconditioned properly. Novel preconditioned ideas (so-called physics based), which were prototypes in the context of reduced MHD, have been adapted for 3D primitive-variable resistive MHD in PIXIE3D, and are currently being extended to Hall MHD. PIXIE3D is fully parallel, employing PETSc for parallelism. PIXIE3D has been thoroughly benchmarked against linear theory and against other available extended MHD codes on nonlinear test problems (such as the GEM reconnection challenge). We are currently in the process of extending such comparisons to fusion-relevant problems in realistic geometries. In this talk, we will describe both the spatial discretization approach and the preconditioning strategy employed for extended MHD in PIXIE3D. We will report on recent benchmarking studies between PIXIE3D and other 3D extended MHD codes, and will demonstrate its usefulness in a variety of fusion-relevant configurations such as Tokamaks and Reversed Field Pinches. (Author)

An MHD heat source based on intermetallic reactions

Energy Technology Data Exchange (ETDEWEB)

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

1991-05-06

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

Numerical modeling of first experiments on PbLi MHD flows in a rectangular duct with foam-based SiC flow channel insert

Energy Technology Data Exchange (ETDEWEB)

Smolentsev, S., E-mail: sergey@fusion.ucla.edu [University of California, Los Angeles (United States); Courtessole, C.; Abdou, M.; Sharafat, S. [University of California, Los Angeles (United States); Sahu, S. [Institute of Plasma Research (India); Sketchley, T. [University of California, Los Angeles (United States)

2016-10-15

Highlights: • Numerical studies were performed as a pre-experimental analysis to the experiment on MHD PbLi flows in a rectangular duct with a flow channel insert (FCI). • Dynamic testing of foam-based SiC foam-based CVD coated FCI has been performed using MaPLE facility at UCLA. • Two physical models were proposed to explain the experimental results and 3D and 2D computations performed using COMSOL, HIMAG and UCLA codes. • The obtained results suggest that more work on FCI development, fabrication and testing has to be done to assure good hermetic properties before the implementation in a fusion device. - Abstract: A flow channel insert (FCI) is the key element of the DCLL blanket concept. The FCI serves as electrical and thermal insulator to reduce the MHD pressure drop and to decouple the temperature-limited ferritic structure from the flowing hot lead-lithium (PbLi) alloy. The main focus of the paper is on numerical computations to simulate MHD flows in the first experiments on PbLi flows in a stainless steel rectangular duct with a foam-based silicon carbide (SiC) FCI. A single uninterrupted long-term (∼6500 h) test has recently been performed on a CVD coated FCI sample in the flowing PbLi in a magnetic field up to 1.5 T at the PbLi temperature of 300 °C using the MaPLE loop at UCLA. An unexpectedly high MHD pressure drop measured in this experiment suggests that a PbLi ingress into the FCI occurred in the course of the experiment, resulting in degradation of electroinsulating FCI properties. The ingress through the protective CVD layer was further confirmed by the post-experimental microscopic analysis of the FCI. The numerical modeling included 2D and 3D computations using HIMAG, COMSOL and a UCLA research code to address important flow features associated with the FCI finite length, fringing magnetic field, rounded FCI corners and also to predict changes in the MHD pressure drop in the unwanted event of a PbLi ingress. Two physical

Sophistication of computational science and fundamental physics simulations

International Nuclear Information System (INIS)

Ishiguro, Seiji; Ito, Atsushi; Usami, Shunsuke; Ohtani, Hiroaki; Sakagami, Hitoshi; Toida, Mieko; Hasegawa, Hiroki; Horiuchi, Ritoku; Miura, Hideaki

2016-01-01

Numerical experimental reactor research project is composed of the following studies: (1) nuclear fusion simulation research with a focus on specific physical phenomena of specific equipment, (2) research on advanced simulation method to increase predictability or expand its application range based on simulation, (3) visualization as the foundation of simulation research, (4) research for advanced computational science such as parallel computing technology, and (5) research aiming at elucidation of fundamental physical phenomena not limited to specific devices. Specifically, a wide range of researches with medium- to long-term perspectives are being developed: (1) virtual reality visualization, (2) upgrading of computational science such as multilayer simulation method, (3) kinetic behavior of plasma blob, (4) extended MHD theory and simulation, (5) basic plasma process such as particle acceleration due to interaction of wave and particle, and (6) research related to laser plasma fusion. This paper reviews the following items: (1) simultaneous visualization in virtual reality space, (2) multilayer simulation of collisionless magnetic reconnection, (3) simulation of microscopic dynamics of plasma coherent structure, (4) Hall MHD simulation of LHD, (5) numerical analysis for extension of MHD equilibrium and stability theory, (6) extended MHD simulation of 2D RT instability, (7) simulation of laser plasma, (8) simulation of shock wave and particle acceleration, and (9) study on simulation of homogeneous isotropic MHD turbulent flow. (A.O.)

Influence of wall couple stress in MHD flow of a micropolar fluid in a porous medium with energy and concentration transfer

Directory of Open Access Journals (Sweden)

Asma Khalid

2018-06-01

Full Text Available The intention here is to investigate the effects of wall couple stress with energy and concentration transfer in magnetohydrodynamic (MHD flow of a micropolar fluid embedded in a porous medium. The mathematical model contains the set of linear conservation forms of partial differential equations. Laplace transforms and convolution technique are used for computation of exact solutions of velocity, microrotations, temperature and concentration equations. Numerical values of skin friction, couple wall stress, Nusselt and Sherwood numbers are also computed. Characteristics for the significant variables on the physical quantities are graphically discussed. Comparison with previously published work in limiting sense shows an excellent agreement. Keywords: Micropolor fluid, Microrotation, MHD, Porosity, Wall couple stress, Exact solutions

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

International Nuclear Information System (INIS)

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

1990-01-01

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

Helium refrigerator-liquefier system for MHD generator

International Nuclear Information System (INIS)

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

1974-01-01

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

Numerical study of MHD supersonic flow control

Science.gov (United States)

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

2017-11-01

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

MHD generator performance analysis for the Advanced Power Train study

Science.gov (United States)

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

1984-01-01

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

Computing in plasma physics

International Nuclear Information System (INIS)

Nuehrenberg, J.

1986-01-01

These proceedings contain the articles presented at the named conference. These concern numerical methods for astrophysical plasmas, the numerical simulation of reversed-field pinch dynamics, methods for numerical simulation of ideal MHD stability of axisymmetric plasmas, calculations of the resistive internal m=1 mode in tokamaks, parallel computing and multitasking, particle simulation methods in plasma physics, 2-D Lagrangian studies of symmetry and stability of laser fusion targets, computing of rf heating and current drive in tokamaks, three-dimensional free boundary calculations using a spectral Green's function method, as well as the calculation of three-dimensional MHD equilibria with islands and stochastic regions. See hints under the relevant topics. (HSI)

Formation, structure, and stability of MHD intermediate shocks

International Nuclear Information System (INIS)

Wu, C.C.

1990-01-01

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

MHD power station with coal gasification

International Nuclear Information System (INIS)

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

1976-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1978-08-01

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

MHD and heat transfer benchmark problems for liquid metal flow in rectangular ducts

International Nuclear Information System (INIS)

Sidorenkov, S.I.; Hua, T.Q.; Araseki, H.

1994-01-01

Liquid metal cooling systems of a self-cooled blanket in a tokamak reactor will likely include channels of rectangular cross section where liquid metal is circulated in the presence of strong magnetic fields. MHD pressure drop, velocity distribution and heat transfer characteristics are important issues in the engineering design considerations. Computer codes for the reliable solution of three-dimensional MHD flow problems are needed for fusion relevant conditions. Argonne National Laboratory and The Efremov Institute have jointly defined several benchmark problems for code validation. The problems, described in this paper, are based on two series of rectangular duct experiments conducted at ANL; one of the series is a joint ANL/Efremov experiment. The geometries consist of variation of aspect ratio and wall thickness (thus wall conductance ratio). The transverse magnetic fields are uniform and nonuniform in the axial direction

PC-based package for interactive assessment of MHD equilibrium and poloidal field coil design in axisymmetric toroidal geometry

International Nuclear Information System (INIS)

Kelleher, W.P.

1987-01-01

In the assessment of Magnetohydrodynamic (MHD) equilibrium and Poloidal Field Coil (PFC) arrangement for toroidal axisymmetric geometry, the Grad-Shafranov equation must be solved, either analytically or numerically. Existing numerical tools have been developed primarily for mainframe usage and can prove cumbersome for screening assessments and parametric evaluations. The objective of this thesis was to develop a personal computer (PC)-based calculational tool for assessing MHD/PFC problems in a highly interactive mode, well suited for scoping studies. The approach adopted involves a two-step process: first the MHD equilibrium is calculated and then the PFC arrangement, consistent with the equilibrium, is determined in an interactive design environment. The PC-based system developed consists of two programs: (1) PCEQ, which solve the MHD equilibrium problem and (2) PFDE-SIGN, which is employed to arrive at a PFC arrangement. PCEQ provides an output file including, but not limited to, the following: poloidal beta, total beta, safety factors, q, on axis and on edge. PCEQ plots the following contours and/or profiles: flux, pressure and toroidal current density, safety factor, and ratio of plasma toroidal field to vacuum field

MHD stability analysis of helical system plasmas

International Nuclear Information System (INIS)

Nakamura, Yuji

2000-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1968-09-01

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

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

Science.gov (United States)

Goedbloed, J. P.

2018-01-01

The extensive studies of MHD instabilities in thermonuclear magnetic confinement experiments, in particular of the tokamak as the most promising candidate for a future energy producing machine, have led to an ‘intuitive’ description based on the energy principle that is very misleading for most astrophysical plasmas. The ‘intuitive’ picture almost directly singles out the dominant stabilizing field line bending energy of the Alfvén waves and, consequently, concentrates on expansion schemes that minimize that contribution. This happens when the wave vector {{k}}0 of the perturbations, on average, is perpendicular to the magnetic field {B}. Hence, all macroscopic instabilities of tokamaks (kinks, interchanges, ballooning modes, ELMs, neoclassical tearing modes, etc) are characterized by satisfying the condition {{k}}0 \\perp {B}, or nearly so. In contrast, some of the major macroscopic instabilities of astrophysical plasmas (the Parker instability and the magneto-rotational instability) occur when precisely the opposite condition is satisfied: {{k}}0 \\parallel {B}. How do those instabilities escape from the dominance of the stabilizing Alfvén wave? The answer to that question involves, foremost, the recognition that MHD spectral theory of waves and instabilities of laboratory plasmas could be developed to such great depth since those plasmas are assumed to be in static equilibrium. This assumption is invalid for astrophysical plasmas where rotational and gravitational accelerations produce equilibria that are at best stationary, and the associated spectral theory is widely, and incorrectly, believed to be non-self adjoint. These complications are addressed, and cured, in the theory of the Spectral Web, recently developed by the author. Using this method, an extensive survey of instabilities of astrophysical plasmas demonstrates how the Alfvén wave is pushed into insignificance under these conditions to give rise to a host of instabilities that do not

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1982-03-01

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

Experimental identification of nonlinear coupling between (intermediate, small)-scale microturbulence and an MHD mode in the core of a superconducting tokamak

Science.gov (United States)

Sun, P. J.; Li, Y. D.; Ren, Y.; Zhang, X. D.; Wu, G. J.; Xu, L. Q.; Chen, R.; Li, Q.; Zhao, H. L.; Zhang, J. Z.; Shi, T. H.; Wang, Y. M.; Lyu, B.; Hu, L. Q.; Li, J.; The EAST Team

2018-01-01

In this paper, we present clear experimental evidence of core region nonlinear coupling between (intermediate, small)-scale microturbulence and an magnetohydrodynamics (MHD) mode during the current ramp-down phase in a set of L-mode plasma discharges in the experimental advanced superconducting tokamak (EAST, Wan et al (2006 Plasma Sci. Technol. 8 253)). Density fluctuations of broadband microturbulence (k\\perpρi˜2{-}5.2 ) and the MHD mode (toroidal mode number m = -1 , poloidal mode number n = 1 ) are measured simultaneously, using a four-channel tangential CO2 laser collective scattering diagnostic in core plasmas. The nonlinear coupling between the broadband microturbulence and the MHD mode is directly demonstrated by showing a statistically significant bicoherence and modulation of turbulent density fluctuation amplitude by the MHD mode.

MHD deceleration of fusion reaction products

International Nuclear Information System (INIS)

Chow, S.; Bohachevsky, I.O.

1979-04-01

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

Resistive MHD studies of high-β-tokamak plasmas

International Nuclear Information System (INIS)

Lynch, V.E.; Carreras, B.A.; Hicks, H.R.; Holmes, J.A.; Garcia, L.

1981-01-01

Numerical calculations have been performed to study the MHD activity in high-β tokamaks such as ISX-B. These initial value calculations built on earlier low β techniques, but the β effects create several new numerical issues. These issues are discussed and resolved. In addition to time-stepping modules, our system of computer codes includes equilibrium solvers (used to provide an initial condition) and output modules, such as a magnetic field line follower and an X-ray diagnostic code. The transition from current driven modes at low β to predominantly pressure driven modes at high β is described. The nonlinear studies yield X-ray emissivity plots which are compared with experiment

MHD simulation of a beat frequency heated plasma

International Nuclear Information System (INIS)

Milroy, R.D.; Capjack, C.E.; James, C.R.; McMullin, J.N.

1976-01-01

The heating of a plasma in a solenoid, with a beat frequency harmonic which is excited at a frequency near to that of a Langmuir mode in a plasma, is examined. It is shown that at high temperatures the heating rate is very insensitive to changes in plasma density. The amount of energy that can be coupled to a plasma in a solenoid with this heating scheme is investigated by using a one-dimensional computer code which incorporates an exact solution of the relevant MHD equations. The absorption of energy from a high powered laser is shown to be significantly enhanced with this process. (author)

Towards Integrated Pulse Detonation Propulsion and MHD Power

Science.gov (United States)

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

1999-01-01

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

Physical Model Development and Benchmarking for MHD Flows in Blanket Design

Energy Technology Data Exchange (ETDEWEB)

Ramakanth Munipalli; P.-Y.Huang; C.Chandler; C.Rowell; M.-J.Ni; N.Morley; S.Smolentsev; M.Abdou

2008-06-05

An advanced simulation environment to model incompressible MHD flows relevant to blanket conditions in fusion reactors has been developed at HyPerComp in research collaboration with TEXCEL. The goals of this phase-II project are two-fold: The first is the incorporation of crucial physical phenomena such as induced magnetic field modeling, and extending the capabilities beyond fluid flow prediction to model heat transfer with natural convection and mass transfer including tritium transport and permeation. The second is the design of a sequence of benchmark tests to establish code competence for several classes of physical phenomena in isolation as well as in select (termed here as “canonical”,) combinations. No previous attempts to develop such a comprehensive MHD modeling capability exist in the literature, and this study represents essentially uncharted territory. During the course of this Phase-II project, a significant breakthrough was achieved in modeling liquid metal flows at high Hartmann numbers. We developed a unique mathematical technique to accurately compute the fluid flow in complex geometries at extremely high Hartmann numbers (10,000 and greater), thus extending the state of the art of liquid metal MHD modeling relevant to fusion reactors at the present time. These developments have been published in noted international journals. A sequence of theoretical and experimental results was used to verify and validate the results obtained. The code was applied to a complete DCLL module simulation study with promising results.

Physical Model Development and Benchmarking for MHD Flows in Blanket Design

International Nuclear Information System (INIS)

Munipalli, Ramakanth; Huang, P.-Y.; Chandler, C.; Rowell, C.; Ni, M.-J.; Morley, N.; Smolentsev, S.; Abdou, M.

2008-01-01

An advanced simulation environment to model incompressible MHD flows relevant to blanket conditions in fusion reactors has been developed at HyPerComp in research collaboration with TEXCEL. The goals of this phase-II project are two-fold: The first is the incorporation of crucial physical phenomena such as induced magnetic field modeling, and extending the capabilities beyond fluid flow prediction to model heat transfer with natural convection and mass transfer including tritium transport and permeation. The second is the design of a sequence of benchmark tests to establish code competence for several classes of physical phenomena in isolation as well as in select (termed here as 'canonical',) combinations. No previous attempts to develop such a comprehensive MHD modeling capability exist in the literature, and this study represents essentially uncharted territory. During the course of this Phase-II project, a significant breakthrough was achieved in modeling liquid metal flows at high Hartmann numbers. We developed a unique mathematical technique to accurately compute the fluid flow in complex geometries at extremely high Hartmann numbers (10,000 and greater), thus extending the state of the art of liquid metal MHD modeling relevant to fusion reactors at the present time. These developments have been published in noted international journals. A sequence of theoretical and experimental results was used to verify and validate the results obtained. The code was applied to a complete DCLL module simulation study with promising results.

Nanosecond electrical explosion of thin aluminum wire in vacuum: experimental and computational investigations

International Nuclear Information System (INIS)

Cochrane, Kyle Robert; Struve, Kenneth William; Rosenthal, Stephen Edgar; McDaniel, Dillon Heirman; Sarkisov, Gennady Sergeevich; Deeney, Christopher

2004-01-01

The experimental and computational investigations of nanosecond electrical explosion of thin Al wire in vacuum are presented. We have demonstrated that increasing the current rate leads to increased energy deposited before voltage collapse. Laser shadowgrams of the overheated Al core exhibit axial stratification with a ∼100 (micro)m period. The experimental evidence for synchronization of the wire expansion and light emission with voltage collapse is presented. Two-wavelength interferometry shows an expanding Al core in a low-ionized gas condition with increasing ionization toward the periphery. Hydrocarbons are indicated in optical spectra and their influence on breakdown physics is discussed. The radial velocity of low-density plasma reaches a value of ∼100 km/s. The possibility of an overcritical phase transition due to high pressure is discussed. 1D MHD simulation shows good agreement with experimental data. MHD simulation demonstrates separation of the exploding wire into a high-density cold core and a low-density hot corona as well as fast rejection of the current from the wire core to the corona during voltage collapse. Important features of the dynamics for wire core and corona follow from the MHD simulation and are discussed.

GRADSPMHD: A parallel MHD code based on the SPH formalism

Science.gov (United States)

Vanaverbeke, S.; Keppens, R.; Poedts, S.

2014-03-01

We present GRADSPMHD, a completely Lagrangian parallel magnetohydrodynamics code based on the SPH formalism. The implementation of the equations of SPMHD in the “GRAD-h” formalism assembles known results, including the derivation of the discretized MHD equations from a variational principle, the inclusion of time-dependent artificial viscosity, resistivity and conductivity terms, as well as the inclusion of a mixed hyperbolic/parabolic correction scheme for satisfying the ∇ṡB→ constraint on the magnetic field. The code uses a tree-based formalism for neighbor finding and can optionally use the tree code for computing the self-gravity of the plasma. The structure of the code closely follows the framework of our parallel GRADSPH FORTRAN 90 code which we added previously to the CPC program library. We demonstrate the capabilities of GRADSPMHD by running 1, 2, and 3 dimensional standard benchmark tests and we find good agreement with previous work done by other researchers. The code is also applied to the problem of simulating the magnetorotational instability in 2.5D shearing box tests as well as in global simulations of magnetized accretion disks. We find good agreement with available results on this subject in the literature. Finally, we discuss the performance of the code on a parallel supercomputer with distributed memory architecture. Catalogue identifier: AERP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERP_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 620503 No. of bytes in distributed program, including test data, etc.: 19837671 Distribution format: tar.gz Programming language: FORTRAN 90/MPI. Computer: HPC cluster. Operating system: Unix. Has the code been vectorized or parallelized?: Yes, parallelized using MPI. RAM: ˜30 MB for a

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

NARCIS (Netherlands)

Goedbloed, J. P.

2018-01-01

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

MINIMIZING THE MHD POTENTIAL ENERGY FOR THE CURRENT HOLE REGION IN TOKAMAKS

International Nuclear Information System (INIS)

CHU, M.S; PARKS, P.B

2004-01-01

The current hole region in the tokamak has been observed to arise naturally during the development of internal transport barriers. The magnetohydrodynamic (MHD) potential energy in the current hole region is shown to be determined completely in terms of the displacements at the edge of the current hole. For modes with finite toroidal mode number n ≠ 0, the minimized potential energy is the same as if the current hole region were a vacuum region. For modes with toroidal mode number n = 0, the displacement is a superposition of three types of independent displacements: a vertical displacement or displacements that compress only the plasma or the toroidal field uniformly. Thus for ideal MHD perturbations of plasma with a current hole, the plasma behaves as if it were bordered by an extra ''internal vacuum region''. The relevance of the present work to computer simulations of plasma with a current hole region is also discussed

ORMEC: a three-dimensional MHD spectral inverse equilibrium code

International Nuclear Information System (INIS)

Hirshman, S.P.; Hogan, J.T.

1986-02-01

The Oak Ridge Moments Equilibrium Code (ORMEC) is an efficient computer code that has been developed to calculate three-dimensional MHD equilibria using the inverse spectral method. The fixed boundary formulation, which is based on a variational principle for the spectral coefficients (moments) of the cylindrical coordinates R and Z, is described and compared with the finite difference code BETA developed by Bauer, Betancourt, and Garabedian. Calculations for the Heliotron, Wendelstein VIIA, and Advanced Toroidal Facility (ATF) configurations are performed to establish the accuracy and mesh convergence properties for the spectral method. 16 refs., 13 figs

Computational Physics Program of the National MFE Computer Center

International Nuclear Information System (INIS)

Mirin, A.A.

1984-12-01

The principal objective of the computational physics group is to develop advanced numerical models for the investigation of plasma phenomena and the simulation of present and future magnetic confinement devices. A summary of the groups activities is presented, including computational studies in MHD equilibria and stability, plasma transport, Fokker-Planck, and efficient numerical and programming algorithms. References are included

Studies of MHD stability using data mining technique in helical plasmas

International Nuclear Information System (INIS)

Yamamoto, Satoshi; Pretty, David; Blackwell, Boyd

2010-01-01

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

Linear Simulations of the Cylindrical Richtmyer-Meshkov Instability in Hydrodynamics and MHD

KAUST Repository

Gao, Song

2013-05-01

The Richtmyer-Meshkov instability occurs when density-stratified interfaces are impulsively accelerated, typically by a shock wave. We present a numerical method to simulate the Richtmyer-Meshkov instability in cylindrical geometry. The ideal MHD equations are linearized about a time-dependent base state to yield linear partial differential equations governing the perturbed quantities. Convergence tests demonstrate that second order accuracy is achieved for smooth flows, and the order of accuracy is between first and second order for flows with discontinuities. Numerical results are presented for cases of interfaces with positive Atwood number and purely azimuthal perturbations. In hydrodynamics, the Richtmyer-Meshkov instability growth of perturbations is followed by a Rayleigh-Taylor growth phase. In MHD, numerical results indicate that the perturbations can be suppressed for sufficiently large perturbation wavenumbers and magnetic fields.

MHD equilibrium of heliotron J plasmas

International Nuclear Information System (INIS)

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

2004-01-01

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

MHD PbLi experiments in MaPLE loop at UCLA

International Nuclear Information System (INIS)

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

2016-01-01

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

MHD PbLi experiments in MaPLE loop at UCLA

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-01

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

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

International Nuclear Information System (INIS)

Li Zhiyun; Krasnopolsky, Ruben; Shang Hsien

2011-01-01

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

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

International Nuclear Information System (INIS)

Sahin, Bahri; Kodal, Ali; Yavuz, Hasbi

1996-01-01

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

Study of MHD problems in liquid metal blankets of fusion reactors

International Nuclear Information System (INIS)

Michael, I.

1984-12-01

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

Preliminary analysis of 500 MWt MHD power plant with oxygen enrichment

Science.gov (United States)

1980-04-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-11-10

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

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

Science.gov (United States)

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

2016-03-01

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

AN MHD AVALANCHE IN A MULTI-THREADED CORONAL LOOP

Energy Technology Data Exchange (ETDEWEB)

Hood, A. W.; Cargill, P. J.; Tam, K. V. [School of Mathematics and Statistics, University of St Andrews, St Andrews, Fife, KY16 9SS (United Kingdom); Browning, P. K., E-mail: awh@st-andrews.ac.uk [School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)

2016-01-20

For the first time, we demonstrate how an MHD avalanche might occur in a multithreaded coronal loop. Considering 23 non-potential magnetic threads within a loop, we use 3D MHD simulations to show that only one thread needs to be unstable in order to start an avalanche even when the others are below marginal stability. This has significant implications for coronal heating in that it provides for energy dissipation with a trigger mechanism. The instability of the unstable thread follows the evolution determined in many earlier investigations. However, once one stable thread is disrupted, it coalesces with a neighboring thread and this process disrupts other nearby threads. Coalescence with these disrupted threads then occurs leading to the disruption of yet more threads as the avalanche develops. Magnetic energy is released in discrete bursts as the surrounding stable threads are disrupted. The volume integrated heating, as a function of time, shows short spikes suggesting that the temporal form of the heating is more like that of nanoflares than of constant heating.

On nonlinear MHD-stability of toroidal magnetized plasma

International Nuclear Information System (INIS)

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

1994-01-01

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

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

International Nuclear Information System (INIS)

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

2017-01-01

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

Nonlinear Diamagnetic Stabilization of Double Tearing Modes in Cylindrical MHD Simulations

Science.gov (United States)

Abbott, Stephen; Germaschewski, Kai

2014-10-01

Double tearing modes (DTMs) may occur in reversed-shear tokamak configurations if two nearby rational surfaces couple and begin reconnecting. During the DTM's nonlinear evolution it can enter an ``explosive'' growth phase leading to complete reconnection, making it a possible driver for off-axis sawtooth crashes. Motivated by similarities between this behavior and that of the m = 1 kink-tearing mode in conventional tokamaks we investigate diamagnetic drifts as a possible DTM stabilization mechanism. We extend our previous linear studies of an m = 2 , n = 1 DTM in cylindrical geometry to the fully nonlinear regime using the MHD code MRC-3D. A pressure gradient similar to observed ITB profiles is used, together with Hall physics, to introduce ω* effects. We find the diamagnetic drifts can have a stabilizing effect on the nonlinear DTM through a combination of large scale differential rotation and mechanisms local to the reconnection layer. MRC-3D is an extended MHD code based on the libMRC computational framework. It supports nonuniform grids in curvilinear coordinates with parallel implicit and explicit time integration.

Entropy stable high order discontinuous Galerkin methods for ideal compressible MHD on structured meshes

Science.gov (United States)

Liu, Yong; Shu, Chi-Wang; Zhang, Mengping

2018-02-01

We present a discontinuous Galerkin (DG) scheme with suitable quadrature rules [15] for ideal compressible magnetohydrodynamic (MHD) equations on structural meshes. The semi-discrete scheme is analyzed to be entropy stable by using the symmetrizable version of the equations as introduced by Godunov [32], the entropy stable DG framework with suitable quadrature rules [15], the entropy conservative flux in [14] inside each cell and the entropy dissipative approximate Godunov type numerical flux at cell interfaces to make the scheme entropy stable. The main difficulty in the generalization of the results in [15] is the appearance of the non-conservative "source terms" added in the modified MHD model introduced by Godunov [32], which do not exist in the general hyperbolic system studied in [15]. Special care must be taken to discretize these "source terms" adequately so that the resulting DG scheme satisfies entropy stability. Total variation diminishing / bounded (TVD/TVB) limiters and bound-preserving limiters are applied to control spurious oscillations. We demonstrate the accuracy and robustness of this new scheme on standard MHD examples.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-10-15

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1973-08-01

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

MHD Ballooning Instability in the Plasma Sheet

International Nuclear Information System (INIS)

Cheng, C.Z.; Zaharia, S.

2003-01-01

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

Computed tomography demonstration of a hypothalamic metastasis

International Nuclear Information System (INIS)

Chakeres, D.W.

1983-01-01

This case report describes a patient who presented with panhypopituitarism secondary to hypothalamic metastasis. A primary hypothalamic abnormality was suggested by computed tomographic (CT) demonstration of a small enhancing circular mass centered within the hypothalamus. Sellar radiographs and cerebral angiography were normal. (orig.)

Computed tomography demonstration of a hypothalamic metastasis

Energy Technology Data Exchange (ETDEWEB)

Chakeres, D.W.

1983-05-01

This case report describes a patient who presented with panhypopituitarism secondary to hypothalamic metastasis. A primary hypothalamic abnormality was suggested by computed tomographic (CT) demonstration of a small enhancing circular mass centered within the hypothalamus. Sellar radiographs and cerebral angiography were normal.

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

Energy Technology Data Exchange (ETDEWEB)

Guidotti, R.

1978-06-15

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

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

International Nuclear Information System (INIS)

Kurita, Gen-ichi

1982-07-01

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

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

International Nuclear Information System (INIS)

Miura, H.; Nakajima, N.

2010-11-01

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

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

International Nuclear Information System (INIS)

Wu, C.C.

1988-01-01

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

Present state of research and development of MHD power generation

International Nuclear Information System (INIS)

Ikeda, Shigeru

1978-01-01

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

Further analysis of MHD acceleration for a hypersonic wind tunnel

International Nuclear Information System (INIS)

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

1995-01-01

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

MHD stability studies in the Proto S-1 A/B device

International Nuclear Information System (INIS)

Munson, C.; Janos, A.; Newhouse, M.; Salberta, E.; Wysocki, F.; Yamada, M.

1982-01-01

An experimental study of the gross MHD stability properties of Spheromak plasmas in the Proto S-1 A/B device is presented. Utilizing the previously demonstrated S-1 slow formation technique, plasmas have been produced which exhibit the predicted tilting instability in a regime of slightly negative field index. A relatively simple passive coil system suggested by numerical stability studies has proven to be effective in stabilizing the observed tilting mode

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

International Nuclear Information System (INIS)

Tokuda, S.

2001-01-01

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

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

International Nuclear Information System (INIS)

Tokuda, S.

2001-01-01

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

Simulating solar MHD

Directory of Open Access Journals (Sweden)

M. Schüssler

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

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

Magnetic stresses in ideal MHD plasmas

DEFF Research Database (Denmark)

Jensen, V.O.

1995-01-01

The concept of magnetic stresses in ideal MHD plasma theory is reviewed and revisited with the aim of demonstrating its advantages as a basis for calculating and understanding plasma equilibria. Expressions are derived for the various stresses that transmit forces in a magnetized plasma...... and it is shown that the resulting magnetic forces on a finite volume element can be obtained by integrating the magnetic stresses over the surface of the element. The concept is used to rederive and discuss the equilibrium conditions for axisymmetric toroidal plasmas, including the virial theorem...... and the Shafranov shift. The method had pedagogical merits as it simplifies the calculations, improves the physical understanding and facilitates an assessment of the approximations made in the calculations....

Bifurcation theory for toroidal MHD instabilities

International Nuclear Information System (INIS)

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

1992-01-01

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

MHD turbulent dynamo in astrophysics: Theory and numerical simulation

Science.gov (United States)

Chou, Hongsong

2001-10-01

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

Computer tomographic demonstration of the popliteal artery entrapment syndrome

International Nuclear Information System (INIS)

Alder, W.; Zwicker, H.

1979-01-01

The popliteal artery entrapment syndrome can be diagnosed by computer tomography with a greater degree of certainty than by angiography. The advantage of computer tomography depends on the simultaneous demonstration of the position of the vessel and of the surrounding muscles and their abnormal situation. (orig.) [de

THEORETICAL MODELING OF THE FEEDBACK STABILIZATION OF EXTERNAL MHD MODES IN TOROIDAL GEOMETRY

International Nuclear Information System (INIS)

CHANCE, M.S.; CHU, M.S.; OKABAYASHI, M.; TURNBULL, A.D.

2001-02-01

OAK-B135 A theoretical framework for understanding the feedback mechanism against external MHD modes has been formulated. Efficient computational tools--the GATO stability code coupled with a substantially modified VACUUM code--have been developed to effectively design viable feedback systems against these modes. The analysis assumed a thin resistive shell and a feedback coil structure accurately modeled in θ, with only a single harmonic variation in φ. Time constants and induced currents in the enclosing resistive shell are calculated. An optimized configuration based on an idealized model have been computed for the DIII-D device. Up to 90% of the effectiveness of an ideal wall can be achieved

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

Science.gov (United States)

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

2015-12-01

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

Conversion software for ANSYS APDL 2 FLUENT MHD magnetic file

International Nuclear Information System (INIS)

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

2016-01-01

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

Concept for a high performance MHD airbreathing-IEC fusion rocket

International Nuclear Information System (INIS)

Froning, H.D. Jr.; Miley, G.H.; Nadler, J.; Shaban, Y.; Momota, H.; Burton, E.

2001-01-01

Previous studies have shown that Single-State-to-Orbit (SSTO) vehicle propellant can be reduced by Magnets-Hydro-Dynamic (MHD) processes that minimize airbreathing propulsion losses and propellant consumption during atmospheric flight, and additional reduction in SSTO propellant is enabled by Inertial Electrostatic Confinement (IEC) fusion, whose more energetic reactions reduce rocket propellant needs. MHD airbreathing propulsion during an SSTO vehicle's initial atmospheric flight phase and IEC fusion propulsion during its final exo-atmospheric flight phase is therefore being explored. Accomplished work is not yet sufficient for claiming such a vehicle's feasibility. But takeoff and propellant mass for an MHD airbreathing and IEC fusion vehicle could be as much as 25 and 40 percent less than one with ordinary airbreathing and IEC fusion; and as much as 50 and 70 percent less than SSTO takeoff and propellant mass with MHD airbreathing and chemical rocket propulsion

Concept for a high performance MHD airbreathing-IEC fusion rocket

Science.gov (United States)

Froning, H. D.; Miley, G. H.; Nadler, J.; Shaban, Y.; Momota, H.; Burton, E.

2001-02-01

Previous studies have shown that Single-State-to-Orbit (SSTO) vehicle propellant can be reduced by Magnets-Hydro-Dynamic (MHD) processes that minimize airbreathing propulsion losses and propellant consumption during atmospheric flight, and additional reduction in SSTO propellant is enabled by Inertial Electrostatic Confinement (IEC) fusion, whose more energetic reactions reduce rocket propellant needs. MHD airbreathing propulsion during an SSTO vehicle's initial atmospheric flight phase and IEC fusion propulsion during its final exo-atmospheric flight phase is therefore being explored. Accomplished work is not yet sufficient for claiming such a vehicle's feasibility. But takeoff and propellant mass for an MHD airbreathing and IEC fusion vehicle could be as much as 25 and 40 percent less than one with ordinary airbreathing and IEC fusion; and as much as 50 and 70 percent less than SSTO takeoff and propellant mass with MHD airbreathing and chemical rocket propulsion. .

MHD peristaltic motion of Johnson-Segalman fluid in a channel with compliant walls

International Nuclear Information System (INIS)

Hayat, T.; Javed, Maryiam; Asghar, S.

2008-01-01

A mathematical model for magnetohydrodynamic (MHD) flow of a Johnson-Segalman fluid in a channel with compliant walls is analyzed. The flow is engendered due to sinusoidal waves on the channel walls. A series solution is developed for the case in which the amplitude ratio is small. Our computations show that the mean axial velocity of a Johnson-Segalman fluid is smaller than that of a viscous fluid. The variations of various interesting dimensionless parameters are graphed and discussed

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

International Nuclear Information System (INIS)

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

2008-10-01

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

Computation of multi-region relaxed magnetohydrodynamic equilibria

Energy Technology Data Exchange (ETDEWEB)

Hudson, S. R.; Lazerson, S. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Dewar, R. L.; Dennis, G.; Hole, M. J.; McGann, M.; Nessi, G. von [Plasma Research Laboratory, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2012-11-15

We describe the construction of stepped-pressure equilibria as extrema of a multi-region, relaxed magnetohydrodynamic (MHD) energy functional that combines elements of ideal MHD and Taylor relaxation, and which we call MRXMHD. The model is compatible with Hamiltonian chaos theory and allows the three-dimensional MHD equilibrium problem to be formulated in a well-posed manner suitable for computation. The energy-functional is discretized using a mixed finite-element, Fourier representation for the magnetic vector potential and the equilibrium geometry; and numerical solutions are constructed using the stepped-pressure equilibrium code, SPEC. Convergence studies with respect to radial and Fourier resolution are presented.

Route analysis for MHD equilibria

International Nuclear Information System (INIS)

Kikuchi, Fumio; Aizawa, Tatsuhiko

1982-01-01

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

Particle orbits and non-ideal MHD stability of Z-pinches

International Nuclear Information System (INIS)

Faghihi, M.

1987-01-01

Particle orbits in a linear EXTRAP vacuum magnetic field configuration are computed. The results indicate that, with an applied electric field along the axis, the particles starting near the magnetic stagnation line would gain substantial energy in the 'free fall', and are the most efficient ones to participate in the ionization process. The acquired energy depends on the electric field strength; the required value of the field is determined. The influence of the pressure anisotropy on the small wavelength internal kink (m=1) mode instability in a Z-pinch, using a generalization of Freidbergs perpendicular MHD model, is investigated. It is found that the stability criterion can not be fulfilled without violation of the fire hose stability condition. This investigation is also performed using the double-adiabatic theory. A finite Larmor radius treatment of the small wavelength kink instabilities for a Z-pinch geometry is presented. It is shown that, when the gyroviscosity is included in the perpendicular MHD model, exponentially growing Alfven waves are predicted even in a homogeneous static equilibrium with isotropic plasma pressure. The Hall effect in the incompressible Hall fluid model is considered. It is found that the Hall parameter reduces the growth rates of the kink modes, but it does not yield complete stabilization (author)

Particle orbits and non-ideal MHD stability of Z-pinches

Energy Technology Data Exchange (ETDEWEB)

Faghihi, M.

1987-01-01

Particle orbits in a linear EXTRAP vacuum magnetic field configuration are computed. The results indicate that, with an applied electric field along the axis, the particles starting near the magnetic stagnation line would gain substantial energy in the 'free fall', and are the most efficient ones to participate in the ionization process. The acquired energy depends on the electric field strength; the required value of the field is determined. The influence of the pressure anisotropy on the small wavelength internal kink (m=1) mode instability in a Z-pinch, using a generalization of Freidbergs perpendicular MHD model, is investigated. It is found that the stability criterion can not be fulfilled without violation of the fire hose stability condition. This investigation is also performed using the double-adiabatic theory. A finite Larmor radius treatment of the small wavelength kink instabilities for a Z-pinch geometry is presented. It is shown that, when the gyroviscosity is included in the perpendicular MHD model, exponentially growing Alfven waves are predicted even in a homogeneous static equilibrium with isotropic plasma pressure. The Hall effect in the incompressible Hall fluid model is considered. It is found that the Hall parameter reduces the growth rates of the kink modes, but it does not yield complete stabilization

Magnetohydrodynamic (MHD) simulation of solar prominence formation

International Nuclear Information System (INIS)

Bao, J.

1987-01-01

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

Energetic particle effects on global MHD modes

International Nuclear Information System (INIS)

Cheng, C.Z.

1990-01-01

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

MHD thrust vectoring of a rocket engine

Science.gov (United States)

Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic

2016-09-01

In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.

Technical support for open-cycle MHD program. Progress report, July--December 1978

Energy Technology Data Exchange (ETDEWEB)

Doss, E D [ed.

1979-06-01

The support program for open-cycle MHD at Argonne National Laboratory is developing the analytical tools needed to investigate the performance of the major components in the combined cycle MHD/steam power system. The analytical effort is centered on the primary components of the system that are unique to MHD and also on the integration of these analytical representations into a model of the entire power producing system. The present project activities include modeling of the combustor, MHD channel, slag separator, and high-temperature air heater. In addition, these models are combined into a complete system model, which is at present capable of carrying out optimizations of the entire system relative to either thermodynamic efficiency or cost of electrical power. Also, in support of other aspects of the open-cycle program, test plans are developed and facility and program reviews are provided upon request in support of the needs and requirements of the DOE/MHD Division.

Characterizing electrostatic turbulence in tokamak plasmas with high MHD activity

Energy Technology Data Exchange (ETDEWEB)

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

2010-09-01

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

Stabilities of MHD rotational discontinuities

International Nuclear Information System (INIS)

Wang, S.

1984-11-01

In this paper, the stabilities of MHD rotational discontinuities are analyzed. The results show that the rotational discontinuities in an incompressible magnetofluid are not always stable with respect to infinitesimal perturbation. The instability condition in a special case is obtained. (author)

MHD stability of tandem mirrors

International Nuclear Information System (INIS)

Poulsen, P.; Molvik, A.; Shearer, J.

1982-01-01

The TMX-Upgrade experiment was described, and the manner in which various plasma parameters could be affected was discussed. The initial analysis of the MHD stability of the tandem mirror was also discussed, with emphasis on the negative tandem configuration

Safety and reliability in superconducting MHD magnets

International Nuclear Information System (INIS)

Laverick, C.; Powell, J.; Hsieh, S.; Reich, M.; Botts, T.; Prodell, A.

1979-07-01

This compilation adapts studies on safety and reliability in fusion magnets to similar problems in superconducting MHD magnets. MHD base load magnet requirements have been identified from recent Francis Bitter National Laboratory reports and that of other contracts. Information relevant to this subject in recent base load magnet design reports for AVCO - Everett Research Laboratories and Magnetic Corporation of America is included together with some viewpoints from a BNL workshop on structural analysis needed for superconducting coils in magnetic fusion energy. A summary of design codes used in large bubble chamber magnet design is also included

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Two dimensional analysis for magnetic flux distribution in electromagnet used for MHD applications

International Nuclear Information System (INIS)

Desai, S.V.; Venkatramani, N.; Rohatgi, V.K.

1984-01-01

Magnetic flux densities in air and iron region of iron core MHD electromagnet, are calculated based on concept of magnetic vector potential. Numerical solution to the problem is obtained by converting partial differential equations into finite difference form with simplifying assumptions. A computer progrm is developed, giving solution by finite difference method. Over-relaxation technique based on Stoke's theorem is applied. Magnetic induction along the transverse axis of the magnet and plot for magnetic induction lines for current = 2420 A is presented. (author)

Stability of a two-volume MRxMHD model in slab geometry

Science.gov (United States)

Tuen, Li Huey

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

Measured MHD equilibrium in Alcator C

International Nuclear Information System (INIS)

Pribyl, P.A.

1986-03-01

A method of processing data from a set of partial Rogowski loops is developed to study the MHD equilibrium in Alcator C. Time dependent poloidal fields in the vicinity of the plasma are calculated from measured currents, with field penetration effects being accounted for. Fields from eddy currents induced by the plasma in the tokamak structure are estimated as well. Each of the set of twelve B/sub θ/ measurements can then be separated into a component from the plasma current and a component from currents external to the pickup loops. Harmonic solutions to Maxwell's equations in toroidal coordinates are fit to these measurements in order to infer the fields everywhere in the vacuum region surrounding the plasma. Using this diagnostic, plasma current, position, shape, and the Shafranov term Λ = β/sub p/ + l/sub i//2 - 1 may be computed, and systematic studies of these plasma parameters are undertaken for Alcator C plasmas

A simplified MHD model of capillary Z-Pinch compared with experiments

Energy Technology Data Exchange (ETDEWEB)

Shapolov, A.A.; Kiss, M.; Kukhlevsky, S.V. [Institute of Physics, University of Pecs (Hungary)

2016-11-15

The most accurate models of the capillary Z-pinches used for excitation of soft X-ray lasers and photolithography XUV sources currently are based on the magnetohydrodynamics theory (MHD). The output of MHD-based models greatly depends on details in the mathematical description, such as initial and boundary conditions, approximations of plasma parameters, etc. Small experimental groups who develop soft X-ray/XUV sources often use the simplest Z-pinch models for analysis of their experimental results, despite of these models are inconsistent with the MHD equations. In the present study, keeping only the essential terms in the MHD equations, we obtained a simplified MHD model of cylindrically symmetric capillary Z-pinch. The model gives accurate results compared to experiments with argon plasmas, and provides simple analysis of temporal evolution of main plasma parameters. The results clarify the influence of viscosity, heat flux and approximations of plasma conductivity on the dynamics of capillary Z-pinch plasmas. The model can be useful for researchers, especially experimentalists, who develop the soft X-ray/XUV sources. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Calculations of stationary solutions for the non linear viscous resistive MHD equations in slab geometry

International Nuclear Information System (INIS)

Edery, D.

1983-11-01

The reduced system of the non linear resistive MHD equations is used in the 2-D one helicity approximation in the numerical computations of stationary tearing modes. The critical magnetic Raynolds number S (S=tausub(r)/tausub(H) where tausub(R) and tausub(H) are respectively the characteristic resistive and hydro magnetic times) and the corresponding linear solution are computed as a starting approximation for the full non linear equations. These equations are then treated numerically by an iterative procedure which is shown to be rapidly convergent. A numerical application is given in the last part of this paper

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

International Nuclear Information System (INIS)

Blottner, F.G.

1978-01-01

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

Axisymmetric MHD simulation of ITB crash and following disruption dynamics of Tokamak plasmas with high bootstrap current

International Nuclear Information System (INIS)

Takei, Nahoko; Tsutsui, Hiroaki; Tsuji-Iio, Shunji; Shimada, Ryuichi; Nakamura, Yukiharu; Kawano, Yasunori; Ozeki, Takahisa; Tobita, Kenji; Sugihara, Masayoshi

2004-01-01

Axisymmetric MHD simulation using the Tokamak Simulation Code demonstrated detailed disruption dynamics triggered by a crash of internal transport barrier in high bootstrap current, high β, reversed shear plasmas. Self-consistent time-evolutions of ohmic current bootstrap current and induced loop voltage profiles inside the disrupting plasma were shown from a view point of disruption characterization and mitigation. In contrast with positive shear plasmas, a particular feature of high bootstrap current reversed shear plasma disruption was computed to be a significant change of plasma current profile, which is normally caused due to resistive diffusion of the electric field induced by the crash of internal transport barrier in a region wider than the internal transport barrier. Discussion based on the simulation results was made on the fastest record of the plasma current quench observed in JT-60U reversed shear plasma disruptions. (author)

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

Science.gov (United States)

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

2017-12-01

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

Theoretical modeling of the feedback stabilization of external MHD modes of toroidal geometry

International Nuclear Information System (INIS)

Chance, M.S.; Chu, M.S.; Okabayashi, M.

2001-01-01

A theoretical framework for understanding the feedback mechanism against external MHD modes has been formulated. Efficient computational tools - the GATO stability code coupled with a substantially modified VACUUM code - have been developed to effectively design viable feedback systems against these modes. The analysis assumed a thin resistive shell and a feedback coil structure accurately modeled in θ, with only a single harmonic variation in φ. An optimized configuration and placement of the feedback and sensor coils as well as the time constants and induced currents in the enclosing resistive shell have been computed for the DIII-D device. Up to 90% of the effectiveness of an ideal wall can be achieved. (author)

MHD repowering of a 250 MWe unit of the TVA Allen Steam Plant

International Nuclear Information System (INIS)

Chapman, J.N.; Attig, R.C.

1992-01-01

In this paper coal fired MHD repowering is considered for the TVA Allen Steam Plant. The performance of the repowered plant is presented. Cost comparisons are made of the cost of repowering with MHD versus the cost of meeting similar standards by installing scrubbers and selective catalytic NO x reduction (SCNR). For repowering of a single 250 MW e unit, the costs favor scrubbing and SCNR. If one considers a single repowering of all three 250 MW e units by a single MHD topping cycle and boiler, MHD repowering is more economical. Environmental emissions from the repowered plant are estimated

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Multimegawatt space nuclear power open-cycle MHD-facility

International Nuclear Information System (INIS)

Pavshuk, V.A.; Panchenko, V.P.

2008-01-01

Paper presents the results of the efforts to calculate the characteristics, the layout and the engineering design of the open cycle space power propulsion on the basis of the high-temperature nuclear reactor for a nuclear rocket engine and the Faraday 20 MW capacity MHD-generator. The IVG-1 heterogeneous channel-vessel reactor ensuring in the course of the experiments hydrogen heating up to 3100 K, up to 5 MPa pressure at the reactor core outlet, up to 5 kg/s flowsheet, up to 220 MW thermal power served as a reactor is considered. One determined the MHD-generator basic parameters, namely: the portion of Cs dope was equal to 20%, the outlet stagnation pressure - 2 MPa, the electric conductivity - ≅30 S/m, the Mach number - ≅0.7, the magnetic field induction - 6 T, the capacity - 20 MW, the specific power removal - ∼4 MJ/kg. Paper describes the design of the MHD-facility with the working fluid momentless discharge and its basic characteristics [ru

Electrode materials for an open-cycle MHD generator channel

International Nuclear Information System (INIS)

Telegin, G.P.; Romanov, A.I.; Akopov, F.A.; Gokhshtejn, Ya.P.; Rekov, A.I.

1983-01-01

The results of investigations, technological developments and tests of high temperature materials for MHD electrodes on the base of zirconium dioxide, stabilized with oxides of calcium, yttrium, neodymium, and dioxide of cerium, chromites, tamping masses from stabilized dioxide of zirconium, cermets are considered. It is established that binary and ternary solutions on the base of zirconium dioxide and alloyed chromites are the perspective materials for the MHD electrodes on pure fuel

Spectrum of resistive MHD modes in cylindrical plasmas

International Nuclear Information System (INIS)

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

1983-07-01

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

MHD activity in the ISX-B tokamak: experimental results and theoretical interpretation

Energy Technology Data Exchange (ETDEWEB)

Carreras, B.A.; Dunlap, J.L.; Bell, J.D.; Charlton, L.A.; Cooper, W.A.; Dory, R.A.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.

1982-01-01

The observed spectrum of MHD fluctuations in the ISX-B tokamak is clearly dominated by the n=1 mode when the q=1 surface is in the plasma. This fact agrees well with theoretical predictions based on 3-D resistive MHD calculations. They show that the (m=1; n=1) mode is then the dominant instability. It drives other n=1 modes through toroidal coupling and n>1 modes through nonlinear couplings. These theoretically predicted mode structures have been compared in detail with the experimentally measured wave forms (using arrays of soft x-ray detectors). The agreement is excellent. More detailed comparisons between theory and experiment have required careful reconstructions of the ISX-B equilibria. The equilibria so constructed have permitted a precise evaluation of the ideal MHD stability properties of ISX-B. The present results indicate that the high ..beta.. ISX-B equilibria are marginally stable to finite eta ideal MHD modes. The resistive MHD calculations also show that at finite ..beta.. there are unstable resistive pressure driven modes.

Some Fluid Dynamic Effects in Large-Scale MHD Generators

Energy Technology Data Exchange (ETDEWEB)

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

1966-10-15

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

Gravitational instability in isotropic MHD plasma waves

Science.gov (United States)

Cherkos, Alemayehu Mengesha

2018-04-01

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

An Arbitrary Lagrangian-Eulerian Discretization of MHD on 3D Unstructured Grids

Energy Technology Data Exchange (ETDEWEB)

Rieben, R N; White, D A; Wallin, B K; Solberg, J M

2006-06-12

We present an arbitrary Lagrangian-Eulerian (ALE) discretization of the equations of resistive magnetohydrodynamics (MHD) on unstructured hexahedral grids. The method is formulated using an operator-split approach with three distinct phases: electromagnetic diffusion, Lagrangian motion, and Eulerian advection. The resistive magnetic dynamo equation is discretized using a compatible mixed finite element method with a 2nd order accurate implicit time differencing scheme which preserves the divergence-free nature of the magnetic field. At each discrete time step, electromagnetic force and heat terms are calculated and coupled to the hydrodynamic equations to compute the Lagrangian motion of the conducting materials. By virtue of the compatible discretization method used, the invariants of Lagrangian MHD motion are preserved in a discrete sense. When the Lagrangian motion of the mesh causes significant distortion, that distortion is corrected with a relaxation of the mesh, followed by a 2nd order monotonic remap of the electromagnetic state variables. The remap is equivalent to Eulerian advection of the magnetic flux density with a fictitious mesh relaxation velocity. The magnetic advection is performed using a novel variant of constrained transport (CT) that is valid for unstructured hexahedral grids with arbitrary mesh velocities. The advection method maintains the divergence free nature of the magnetic field and is second order accurate in regions where the solution is sufficiently smooth. For regions in which the magnetic field is discontinuous (e.g. MHD shocks) the method is limited using a novel variant of algebraic flux correction (AFC) which is local extremum diminishing (LED) and divergence preserving. Finally, we verify each stage of the discretization via a set of numerical experiments.

Analytic MHD Theory for Earth's Bow Shock at Low Mach Numbers

Science.gov (United States)

Grabbe, Crockett L.; Cairns, Iver H.

1995-01-01

A previous MHD theory for the density jump at the Earth's bow shock, which assumed the Alfven M(A) and sonic M(s) Mach numbers are both much greater than 1, is reanalyzed and generalized. It is shown that the MHD jump equation can be analytically solved much more directly using perturbation theory, with the ordering determined by M(A) and M(s), and that the first-order perturbation solution is identical to the solution found in the earlier theory. The second-order perturbation solution is calculated, whereas the earlier approach cannot be used to obtain it. The second-order terms generally are important over most of the range of M(A) and M(s) in the solar wind when the angle theta between the normal to the bow shock and magnetic field is not close to 0 deg or 180 deg (the solutions are symmetric about 90 deg). This new perturbation solution is generally accurate under most solar wind conditions at 1 AU, with the exception of low Mach numbers when theta is close to 90 deg. In this exceptional case the new solution does not improve on the first-order solutions obtained earlier, and the predicted density ratio can vary by 10-20% from the exact numerical MHD solutions. For theta approx. = 90 deg another perturbation solution is derived that predicts the density ratio much more accurately. This second solution is typically accurate for quasi-perpendicular conditions. Taken together, these two analytical solutions are generally accurate for the Earth's bow shock, except in the rare circumstance that M(A) is less than or = 2. MHD and gasdynamic simulations have produced empirical models in which the shock's standoff distance a(s) is linearly related to the density jump ratio X at the subsolar point. Using an empirical relationship between a(s) and X obtained from MHD simulations, a(s) values predicted using the MHD solutions for X are compared with the predictions of phenomenological models commonly used for modeling observational data, and with the predictions of a

Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report

International Nuclear Information System (INIS)

Tataronis, J. A.

2004-01-01

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

3-D nonlinear evolution of MHD instabilities

International Nuclear Information System (INIS)

Bateman, G.; Hicks, H.R.; Wooten, J.W.

1977-03-01

The nonlinear evolution of ideal MHD internal instabilities is investigated in straight cylindrical geometry by means of a 3-D initial-value computer code. These instabilities are characterized by pairs of velocity vortex cells rolling off each other and helically twisted down the plasma column. The cells persist until the poloidal velocity saturates at a few tenths of the Alfven velocity. The nonlinear phase is characterized by convection around these essentially fixed vortex cells. For example, the initially centrally peaked temperature profile is convected out and around to form an annulus of high temperature surrounding a small region of lower temperature. Weak, centrally localized instabilities do not alter the edge of the plasma. Strong, large-scale instabilities, resulting from a stronger longitudinal equilibrium current, drive the plasma against the wall. After three examples of instability are analyzed in detail, the numerical methods and their verification are discussed

High pressure MHD coal combustors investigation, phase 2

Science.gov (United States)

Iwata, H.; Hamberg, R.

1981-05-01

A high pressure MHD coal combustor was investigated. The purpose was to acquire basic design and support engineering data through systematic combustion experiments at the 10 and 20 thermal megawatt size and to design a 50 MW/sub t/ combustor. This combustor is to produce an electrically conductive plasma generated by the direct combustion of pulverized coal with hot oxygen enriched vitiated air that is seeded with potassium carbonate. Vitiated air and oxygen are used as the oxidizer, however, preheated air will ultimately be used as the oxidizer in coal fired MHD combustors.

On MHD nonlinear stretching flow of Powell–Eyring nanomaterial

Directory of Open Access Journals (Sweden)

Tasawar Hayat

Full Text Available This communication addresses the magnetohydrodynamic (MHD flow of Powell–Eyring nanomaterial bounded by a nonlinear stretching sheet. Novel features regarding thermophoresis and Brownian motion are taken into consideration. Powell–Eyring fluid is electrically conducted subject to non-uniform applied magnetic field. Assumptions of small magnetic Reynolds number and boundary layer approximation are employed in the mathematical development. Zero nanoparticles mass flux condition at the sheet is selected. Adequate transformation yield nonlinear ordinary differential systems. The developed nonlinear systems have been computed through the homotopic approach. Effects of different pertinent parameters on velocity, temperature and concentration fields are studied and analyzed. Further numerical data of skin friction and heat transfer rate is also tabulated and interpreted. Keywords: Powell–Eyring fluid, Magnetohydrodynamics, Nanomaterial, Nonlinear stretching surface

Nonlinear MHD dynamo operating at equipartition

DEFF Research Database (Denmark)

Archontis, V.; Dorch, Bertil; Nordlund, Åke

2007-01-01

Context.We present results from non linear MHD dynamo experiments with a three-dimensional steady and smooth flow that drives fast dynamo action in the kinematic regime. In the saturation regime, the system yields strong magnetic fields, which undergo transitions between an energy-equipartition a......Context.We present results from non linear MHD dynamo experiments with a three-dimensional steady and smooth flow that drives fast dynamo action in the kinematic regime. In the saturation regime, the system yields strong magnetic fields, which undergo transitions between an energy......, and that it can saturate at a level significantly higher than intermittent turbulent dynamos, namely at energy equipartition, for high values of the magnetic and fluid Reynolds numbers. The equipartition solution however does not remain time-independent during the simulation but exhibits a much more intricate...

Evolution of the MHD sheet pinch

International Nuclear Information System (INIS)

Matthaeus, W.H.; Montgomery, D.

1979-01-01

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

INCORPORATING AMBIPOLAR AND OHMIC DIFFUSION IN THE AMR MHD CODE RAMSES

International Nuclear Information System (INIS)

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

2012-01-01

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

Paradoxical emboli: demonstration using helical computed tomography of the pulmonary artery associated with abdominal computed tomography

International Nuclear Information System (INIS)

Delalu, P.; Ferretti, G.R.; Bricault, I.; Ayanian, D.; Coulomb, M.

2000-01-01

We report the case of a 60-year-old woman with a recent history of a cerebrovascular accident. Because of clinical suspicion of pulmonary embolism and negative Doppler ultrasound findings of the lower limbs, spiral computed tomography of the pulmonary artery was performed and demonstrated pulmonary emboli. We emphasize the role of computed tomography of the abdomen, performed 3 min after the thoracic acquisition, which showed an unsuspected thrombus within the abdominal aorta and the left renal artery with infarction of the left kidney. Paradoxical embolism was highly suspected on computed tomography data and confirmed by echocardiography which demonstrated a patent foramen ovale. (orig.)

Demonstration for novel self-organization theory by three-dimensional magnetohydrodynamic simulation

International Nuclear Information System (INIS)

Kondoh, Yoshiomi; Hosaka, Yasuo; Liang, Jia-Ling.

1993-03-01

It is demonstrated by three-dimensional simulations for resistive magnetohydrodynamic (MHD) plasmas with both 'spatially nonuniform resistivity η' and 'uniformη' that the attractor of the dissipative structure in the resistive MHD plasmas is given by ∇ x (ηj) = (α/2)B which is derived from a novel self-organization theory based on the minimum dissipation rate profile. It is shown by the simulations that the attractor is reduced to ∇ x B = λB in the special case with the 'uniformη' and no pressure gradient. (author)

CosmosDG: An hp-adaptive Discontinuous Galerkin Code for Hyper-resolved Relativistic MHD

Science.gov (United States)

Anninos, Peter; Bryant, Colton; Fragile, P. Chris; Holgado, A. Miguel; Lau, Cheuk; Nemergut, Daniel

2017-08-01

We have extended Cosmos++, a multidimensional unstructured adaptive mesh code for solving the covariant Newtonian and general relativistic radiation magnetohydrodynamic (MHD) equations, to accommodate both discrete finite volume and arbitrarily high-order finite element structures. The new finite element implementation, called CosmosDG, is based on a discontinuous Galerkin (DG) formulation, using both entropy-based artificial viscosity and slope limiting procedures for the regularization of shocks. High-order multistage forward Euler and strong-stability preserving Runge-Kutta time integration options complement high-order spatial discretization. We have also added flexibility in the code infrastructure allowing for both adaptive mesh and adaptive basis order refinement to be performed separately or simultaneously in a local (cell-by-cell) manner. We discuss in this report the DG formulation and present tests demonstrating the robustness, accuracy, and convergence of our numerical methods applied to special and general relativistic MHD, although we note that an equivalent capability currently also exists in CosmosDG for Newtonian systems.

CosmosDG: An hp -adaptive Discontinuous Galerkin Code for Hyper-resolved Relativistic MHD

Energy Technology Data Exchange (ETDEWEB)

Anninos, Peter; Lau, Cheuk [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550 (United States); Bryant, Colton [Department of Engineering Sciences and Applied Mathematics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois, 60208 (United States); Fragile, P. Chris [Department of Physics and Astronomy, College of Charleston, 66 George Street, Charleston, SC 29424 (United States); Holgado, A. Miguel [Department of Astronomy and National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801 (United States); Nemergut, Daniel [Operations and Engineering Division, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2017-08-01

We have extended Cosmos++, a multidimensional unstructured adaptive mesh code for solving the covariant Newtonian and general relativistic radiation magnetohydrodynamic (MHD) equations, to accommodate both discrete finite volume and arbitrarily high-order finite element structures. The new finite element implementation, called CosmosDG, is based on a discontinuous Galerkin (DG) formulation, using both entropy-based artificial viscosity and slope limiting procedures for the regularization of shocks. High-order multistage forward Euler and strong-stability preserving Runge–Kutta time integration options complement high-order spatial discretization. We have also added flexibility in the code infrastructure allowing for both adaptive mesh and adaptive basis order refinement to be performed separately or simultaneously in a local (cell-by-cell) manner. We discuss in this report the DG formulation and present tests demonstrating the robustness, accuracy, and convergence of our numerical methods applied to special and general relativistic MHD, although we note that an equivalent capability currently also exists in CosmosDG for Newtonian systems.

CosmosDG: An hp -adaptive Discontinuous Galerkin Code for Hyper-resolved Relativistic MHD

International Nuclear Information System (INIS)

Anninos, Peter; Lau, Cheuk; Bryant, Colton; Fragile, P. Chris; Holgado, A. Miguel; Nemergut, Daniel

2017-01-01

We have extended Cosmos++, a multidimensional unstructured adaptive mesh code for solving the covariant Newtonian and general relativistic radiation magnetohydrodynamic (MHD) equations, to accommodate both discrete finite volume and arbitrarily high-order finite element structures. The new finite element implementation, called CosmosDG, is based on a discontinuous Galerkin (DG) formulation, using both entropy-based artificial viscosity and slope limiting procedures for the regularization of shocks. High-order multistage forward Euler and strong-stability preserving Runge–Kutta time integration options complement high-order spatial discretization. We have also added flexibility in the code infrastructure allowing for both adaptive mesh and adaptive basis order refinement to be performed separately or simultaneously in a local (cell-by-cell) manner. We discuss in this report the DG formulation and present tests demonstrating the robustness, accuracy, and convergence of our numerical methods applied to special and general relativistic MHD, although we note that an equivalent capability currently also exists in CosmosDG for Newtonian systems.

Statistical Theory of the Ideal MHD Geodynamo

Science.gov (United States)

Shebalin, J. V.

2012-01-01

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

MHD magnet technology development program summary, September 1982

Energy Technology Data Exchange (ETDEWEB)

1983-11-01

The program of MHD magnet technology development conducted for the US Department of Energy by the Massachusetts Institute of Technology during the past five years is summarized. The general strategy is explained, the various parts of the program are described and the results are discussed. Subjects covered include component analysis, research and development aimed at improving the technology base, preparation of reference designs for commercial-scale magnets with associated design evaluations, manufacturability studies and cost estimations, the detail design and procurement of MHD test facility magnets involving transfer of technology to industry, investigations of accessory subsystem characteristics and magnet-flow-train interfacing considerations and the establishment of tentative recommendations for design standards, quality assurance procedures and safety procedures. A systematic approach (framework) developed to aid in the selection of the most suitable commercial-scale magnet designs is presented and the program status as of September 1982 is reported. Recommendations are made for future work needed to complete the design evaluation and selection process and to provide a sound technological base for the detail design and construction of commercial-scale MHD magnets. 85 references.

MHD magnet technology development program summary, September 1982

International Nuclear Information System (INIS)

1983-11-01

The program of MHD magnet technology development conducted for the US Department of Energy by the Massachusetts Institute of Technology during the past five years is summarized. The general strategy is explained, the various parts of the program are described and the results are discussed. Subjects covered include component analysis, research and development aimed at improving the technology base, preparation of reference designs for commercial-scale magnets with associated design evaluations, manufacturability studies and cost estimations, the detail design and procurement of MHD test facility magnets involving transfer of technology to industry, investigations of accessory subsystem characteristics and magnet-flow-train interfacing considerations and the establishment of tentative recommendations for design standards, quality assurance procedures and safety procedures. A systematic approach (framework) developed to aid in the selection of the most suitable commercial-scale magnet designs is presented and the program status as of September 1982 is reported. Recommendations are made for future work needed to complete the design evaluation and selection process and to provide a sound technological base for the detail design and construction of commercial-scale MHD magnets. 85 references

Diagnostics for a coal-fired MHD retrofit of an existing power station

Energy Technology Data Exchange (ETDEWEB)

Cook, R L; Shepard, W S [Mississippi State Univ. (USA). Diagnostic Instrumentation and Analysis Lab.

1990-01-01

MHD flows represent one of the most severe environments encountered by gasdynamic diagnostics. Special state-of-the-art techniques and instrumentation systems are required to monitor and collect data for the MHD components, and these diagnostic systems must operate under very severe environmental and magnetic field conditions. The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University has developed, and is continuing to develop, advanced optical diagnostic techniques and instrumentation systems to provide nonintrusive, remote real-time measurements and to operate successfully in the industrial-like environment of a large-scale MHD retrofit power station. Such diagnostic instrumentation can provide the information to completely evaluate the performance of individual components, as well as, the entire power plant. It is essential to determine as much detail as possible about the various component operations in an MHD retrofit system so that a commercial plant design can be optimized quickly. This paper discusses the instrumentation systems which DIAL proposed for an MHD retrofit of an existing power station. Instruments which have been making measurements on the U.S. MHD test facilities for several years are presented, along with instruments which will be available within two years. Parameters to be measured along with location and frequency are discussed in detail. These parameters include electron density, electrical conductivity, K-atom density, gas temperature, gas velocity, temperature and velocity profiles, gas composition, and particle size, number, density and distrib00000

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

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

MHD simulation of Columbia HBT

International Nuclear Information System (INIS)

Li, X.L.

1987-01-01

The plasma of Columbia High Beta Tokamak (HBT) is studied numerically by using the two dimensional resistive MHD model. The main object of this work is to understand the high beta formation process of HBT plasma and to compare the simulation with the experiments. 21 refs., 48 figs., 2 tabs

Ion temperature increase during MHD events on the TST-2 spherical tokamak

International Nuclear Information System (INIS)

Ejiri, A.; Shiraiwa, S.; Takase, Y.; Yamada, T.; Nagashima, Y.; Kasahara, H.; Iijima, D.; Kobori, Y.; Nishi, T.; Taniguchi, T.; Aramasu, M.; Ohara, S.; Ushigome, M.; Yamagishi, K.

2003-01-01

Various types of MHD events including internal reconnection events are studied on the TST-2 spherical tokamak. In weak MHD events no positive current spike was observed, but in strong MHD events with positive current spikes, a rapid and significant impurity ion temperature increase was observed. The decrease in the poloidal magnetic energy is the most probable energy source for ion heating. The plasma current shows a stepwise change. The magnitude of this step correlates with the temperature increase and is found to be a good indicator of the strength of each event. (author)

Report on evaluation concerning R and D of magneto hydrodynamic (MHD) generation. Introduction; Denji ryutai (MHD) hatsuden no kenkyu kaihatsu ni kansuru hyoka hokokusho. Soron

Energy Technology Data Exchange (ETDEWEB)

NONE

1984-03-01

Evaluation was conducted concerning R and D on magneto hydrodynamic (MHD) generation, with proposals made for the future R and D. As a result of the experimental operation and studies of the Mark 7 machine for MHD generation, a cold wall type generation channel was found promising in the long-term durability under MHD generation conditions. In addition, R and D was conducted on the exhaust gas control system that fulfilled an environmental standard, seed recovery method, grasp of seed coagulation state, etc. The R and D on element technologies were carried out along with the R and D of the Mark 7 and played a role in the backup of its experiment. MHD generation presents a large number of attractive characteristics, with its development expected in the future. However, it seems too early to immediately move on to the next step. Examinations should be made on such matters as comparisons with various kinds of new power generation systems using coal, trends in foreign countries particularly the U-500 project of the Soviet Union, the ideal system for more efficient development, and possibility of international cooperation. (NEDO)

Linear MHD stability analysis of post-disruption plasmas in ITER

Energy Technology Data Exchange (ETDEWEB)

Aleynikova, K., E-mail: ksenia.aleynikova@gmail.com [EURATOM Association, Max-Planck-Institut für Plasmaphysik (Germany); Huijsmans, G. T. A. [ITER Organization (France); Aleynikov, P. [EURATOM Association, Max-Planck-Institut für Plasmaphysik (Germany)

2016-05-15

Most of the plasma current can be replaced by a runaway electron (RE) current during plasma disruptions in ITER. In this case the post-disruption plasma current profile is likely to be more peaked than the pre-disruption profile. The MHD activity of such plasma will affect the runaway electron generation and confinement and the dynamics of the plasma position evolution (Vertical Displacement Event), limiting the timeframe for runaway electrons and disruption mitigation. In the present paper, we evaluate the influence of the possible RE seed current parameters on the onset of the MHD instabilities. By varying the RE seed current profile, we search for subsequent plasma evolutions with the highest and the lowest MHD activity. This information can be applied to a development of desirable ITER disruption scenario.

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Demonstrating Operating System Principles via Computer Forensics Exercises

Science.gov (United States)

Duffy, Kevin P.; Davis, Martin H., Jr.; Sethi, Vikram

2010-01-01

We explore the feasibility of sparking student curiosity and interest in the core required MIS operating systems course through inclusion of computer forensics exercises into the course. Students were presented with two in-class exercises. Each exercise demonstrated an aspect of the operating system, and each exercise was written as a computer…

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

Directory of Open Access Journals (Sweden)

L.-N. Hau

2007-09-01

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

Hall effects on MHD flow of heat generating/absorbing fluid through porous medium in a rotating parallel plate channel

Science.gov (United States)

Swarnalathamma, B. V.; Krishna, M. Veera

2017-07-01

We studied heat transfer on MHD convective flow of viscous electrically conducting heat generating/absorbing fluid through porous medium in a rotating channel under uniform transverse magnetic field normal to the channel and taking Hall current. The flow is governed by the Brinkman's model. The diagnostic solutions for the velocity and temperature are obtained by perturbation technique and computationally discussed with respect to flow parameters through the graphs. The skin friction and Nusselt number are also evaluated and computationally discussed with reference to pertinent parameters in detail.

A study on the fusion reactor - Development of MHD stability and transport code for KT-2 tokamak

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Koo; Shin, Kyo Jin [Pohang University of Science and Tecnology, Pohang (Korea, Republic of)

1996-08-01

MHD Stability analyses for KT-2 Tokamak were carried out by using CART (Resistive 3-D) Code. Linear Growth rates and linear perturbed eigen function of both N=0 axisymmetric mode and N=1 kink modes of highly elongated tokamak plasmas, in the presence of a conducting wall at various distances are computed and linear and nonlinear evolution of N=0 axisymmetric modes are simulated. 26 refs., 25 figs. (author)

Modelling of diamagnetic stabilization of ideal MHD eigenmodes associated with the transport barrier

International Nuclear Information System (INIS)

Huysmans, G.; Sharapov, S.; Mikhailovskii, A.; Kerner, W.

2001-01-01

A new code, MISHKA-D (Drift MHD), has been developed as an extension of the ideal MHD code MISHKA-1 in order to investigate the finite gyroradius stabilizing effect of ion diamagnetic drift frequency, ω *i , on linear ideal MHD eigenmodes in tokamaks with shaped plasma cross-section. The MISHKA-D code gives a self-consistent computation of both stable and unstable eigenmodes with eigenvalues [γ] ≅ ω *i in plasmas with strong radial variation in the ion diamagnetic frequency. Test results of the MISHKA-D code show good agreement with the analytically obtained ω *i -spectrum and stability limits of the internal kink mode, n/m=1/1, used as a benchmark case. Finite-n ballooning and low-n kink (peeling) modes in the edge transport barrier just inside the separatrix are studied for H-mode plasma with the ω *i -effect included. The ion diamagnetic stabilization of the ballooning modes is found to be most effective for narrow edge pedestals. For low enough plasma density the ω *i - stabilization can lead to a second zone of ballooning stability, in which all the ballooning modes are stable for any value of the pressure gradient. For internal transport barriers typical of JET optimised shear discharges, the stabilizing influence of ion diamagnetic frequency on the n=1 global pressure driven disruptive mode is studied. A strong radial variation of ω *i is found to significantly decrease the stabilizing ω *i - effect on the n=1 mode, in comparison with the case of constant ω *i estimated at the foot of the internal transport barrier. (author)

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

International Nuclear Information System (INIS)

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

1986-01-01

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

MHD flow layer formation at boundaries of magnetic islands in tokamak plasmas

International Nuclear Information System (INIS)

Jiaqi Dong; Yongxing Long; Zongze Mou; Jinhua Zhang

2005-01-01

Non-linear development of double tearing modes induced by electron viscosity is numerically simulated. MHD flow layers are demonstrated to merge in the development of the modes. The sheared flows are shown to lie just at the boundaries of the magnetic islands, and to have sufficient levels required for internal transport barrier (ITB) formation. Possible correlation between the layer formation and triggering of experimentally observed ITBs, preferentially formed in proximities of rational flux surfaces of low safety factors, is discussed. (author)

Ceramic component for M.H.D electrode

International Nuclear Information System (INIS)

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

1980-01-01

A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hfsub(x)Insub(y)Asub(z)O 2 where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a rare earth or yttrium. The rare earth may be Yb, Tb, Pr or Ce. The component is suitable for use in the fabrication of MHD electrodes or as the current lead-out portion of a composite electrode with other ceramic components. An MHD electrode comprises a cap of a known ceramic, e.g. stabilised zirconium or hafnium oxide or terbium stabilised hafnium, a current lead-out ceramic according to the invention, and a copper frame. (author)

Ideal MHD B limits in the BIG DEE tokamak

International Nuclear Information System (INIS)

Helton, F.J.; Bernard, L.C.; Greene, J.M.

1983-01-01

Using D-D reactions, tokamak reactors become economically attractive when B (the ratio of volume averaged pressure to magnetic pressure) exceeds 5 percent. Ideal MID instabilities are of great concern because they have the potential to limit B below this range and so extensive studies have been done to determine ideal MHD B limits. As B increases with inverse aspect ratio, elongation and triangularity, the Doublet III upgrade machine -- BIG DEE -- is particularly suited to study the possibility of very high B. The authors have done computations to determine ideal MHD B limits for various plasma shapes and elongations in BIG DEE. They have determined that for q at the plasma surface greater than 2, B is limited by the ballooning mode if the wall is reasonably close to the plasma surface (d/a < 1.5 where d and a are the wall and plasma radii respectively). On the other hand, for q at the plasma surface less than 2, the n=1 external kink is unstable even with a wall close by. Thus, relevant values of limiting B can be obtained by assuming that the external kink limits the value of q at the limiter to a value greater than 2 and that the ballooning modes limit B. Under this assumption, a relevant B limit for the BIG DEE would be over 18%. For such an equilibrium, the wall position necessary to stabilize the n=1 and n=2 modes is 2a and the equilibrium is stable for n=3

Combining MHD Airbreathing and Fusion Rocket Propulsion for Earth-to-Orbit Flight

International Nuclear Information System (INIS)

Froning, H. D. Jr; Yang, Yang; Momota, H.; Burton, E.; Miley, G. H.; Luo, Nie

2005-01-01

Previous studies have shown that Single-State-to-Orbit (SSTO) vehicle propellant can be reduced by Magnets-Hydro-Dynamic (MHD) processes that minimize airbreathing propulsion losses and propellant consumption during atmospheric flight. Similarly additional reduction in SSTO propellant is enabled by Inertial Electrostatic Confinement (IEC) fusion, whose more energetic reactions reduce rocket propellant needs. MHD airbreathing propulsion during an SSTO vehicle's initial atmospheric flight phase and IEC fusion propulsion during its final exo-atmospheric flight phase is therefore being explored. Accomplished work is not yet sufficient for claiming such a vehicle's feasibility. But takeoff and propellant mass for an MHD airbreathing and IEC fusion vehicle could be as much as 25 and 40 percent less than one with ordinary airbreathing and IEC fusion; and as much as 50 and 70 percent less than SSTO takeoff and propellant mass with MHD airbreathing and chemical rocket propulsion. Thus this unusual combined cycle engine shows great promise for performance gains beyond contemporary combined-cycle airbreathing engines

MHD dynamo action in space plasmas

International Nuclear Information System (INIS)

Faelthammar, C.G.

1984-05-01

Electric currents are now recognized to play a major role in the physical process of the Earths magnetosphere as well as in distant astrophysical plasmas. In driving these currents MHD dynamos as well as generators of a thermoelectric nature are important. The primary source of power for the Earths magnetospheric process is the solar wind, which supplies a voltage of the order of 200 kV across the magnetosphere. The direction of the large-scale solar wind electric field varies of many different time scales. The power input to the magnetosphere is closely correlated with the direction of the large-scale solar wind electric field in such a fashion as to mimick the response of a half-wave rectifier with a down-to-dusk conduction direction. Behind this apparently simple response there are complex plasma physical processes that are still very incompletely understood. They are intimately related to auroras, magnetic storms, radiation belts and changes in magnetospheric plasma populations. Similar dynamo actions should occur at other planets having magnetospheres. Recent observations seem to indicate that part of the power input to the Earths magnetosphere comes through MHD dynamo action of a forced plasma flow inside the flanks of the magnetopause and may play a role in other parts of the magnetosphere, too. An example of a cosmical MHD connected to a solid load is the corotating plasma of Jupiters inner magnetosphere, sweeping past the plants inner satelites. In particular the electric currents thereby driven to and from the satellite Io have attracted considerable interest.(author)

The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

Science.gov (United States)

Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

2018-01-01

Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence

Calculation of magnetic field and electromagnetic forces in MHD superconducting magnets

International Nuclear Information System (INIS)

Martinelli, G.; Morini, A.; Moisio, M.F.

1992-01-01

The realization of a superconducting prototype magnet for MHD energy conversion is under development in Italy. Electromechanical industries and University research groups are involved in the project. The paper deals with analytical methods developed at the Department of Electrical Engineering of Padova University for calculating magnetic field and electromagnetic forces in MHD superconducting magnets and utilized in the preliminary design of the prototype

Three-dimensional nonlinear ideal MHD equilibria with field-aligned incompressible and compressible flows

International Nuclear Information System (INIS)

Moawad, S. M.; Ibrahim, D. A.

2016-01-01

The equilibrium properties of three-dimensional ideal magnetohydrodynamics (MHD) are investigated. Incompressible and compressible flows are considered. The governing equations are taken in a steady state such that the magnetic field is parallel to the plasma flow. Equations of stationary equilibrium for both of incompressible and compressible MHD flows are derived and described in a mathematical mode. For incompressible MHD flows, Alfvénic and non-Alfvénic flows with constant and variable magnetofluid density are investigated. For Alfvénic incompressible flows, the general three-dimensional solutions are determined with the aid of two potential functions of the velocity field. For non-Alfvénic incompressible flows, the stationary equilibrium equations are reduced to two differential constraints on the potential functions, flow velocity, magnetofluid density, and the static pressure. Some examples which may be of some relevance to axisymmetric confinement systems are presented. For compressible MHD flows, equations of the stationary equilibrium are derived with the aid of a single potential function of the velocity field. The existence of three-dimensional solutions for these MHD flows is investigated. Several classes of three-dimensional exact solutions for several cases of nonlinear equilibrium equations are presented.

Solar furnace experiments for thermophysical properties studies of rare-earth oxide MHD materials

International Nuclear Information System (INIS)

Coutures, J.P.

1978-01-01

Some high temperature work performed with solar furnaces on rare earth oxides is reviewed. Emphasis is on the thermophysical properties (refractoriness, vaporization behavior) and the nature of solid solution on materials which could be used as electrodes for the MHD process. As new sources of energy are being developed due to the world energy crisis, MHD conversion could be useful. The development of MHD systems requires new efforts to develop and optimize materials properties. These materials must have good mechanical and electrical properties (if possible, pure electronic conduction with good emission). Because of the high temperature in MHD generators, the materials for electrodes must have good refractoriness and also must resist vaporization and corrosion at high temperature (T approx. 2000 0 C). Rare-earth oxides are the basic components for most of the MHD electrode materials and it is important to know their thermophysical properties (solidification point phase transitions, heat of fusion and of phase transition, vapor pressure). Because of the high temperature range and the nature of the atmosphere in which these experiments must be performed, special equipment adapted to solar furnaces was developed

Recent progress on MHD-induced loss of D-D fusion products in TFTR

International Nuclear Information System (INIS)

Zweben, S.J.; Darrow, D.S.; Budny, R.V.; Cheng, C.Z.; Fredrickson, E.D.; Herrmann, H.; Mynick, H.E.; Schivell, J.

1993-08-01

This paper reviews the recent progress made toward understanding the MHD-induced loss of D-D fusion products which has been seen on TFTR since 1988. These measurements have been made using the ''lost alpha'' diagnostic, which is described briefly. The largest MHD- induced loss occurs with coherent 3/2 or 2/1 MHD activity (kink/tearing modes), which can cause up to ∼3--5 times the first-orbit loss at I∼1.6--1.8 MA, roughly a ∼20--30% global los of D-D fusion products. Modeling of these MHD-induced losses has progressed to the point where the basic loss mechanism can be accounted for qualitatively, but the experimental results can not yet be understood quantitatively. Several alpha loss codes are being developed to improve the quantitative comparison between experiment and theory

Disappearance of Anisotropic Intermittency in Large-amplitude MHD Turbulence and Its Comparison with Small-amplitude MHD Turbulence

Science.gov (United States)

Yang, Liping; Zhang, Lei; He, Jiansen; Tu, Chuanyi; Li, Shengtai; Wang, Xin; Wang, Linghua

2018-03-01

Multi-order structure functions in the solar wind are reported to display a monofractal scaling when sampled parallel to the local magnetic field and a multifractal scaling when measured perpendicularly. Whether and to what extent will the scaling anisotropy be weakened by the enhancement of turbulence amplitude relative to the background magnetic strength? In this study, based on two runs of the magnetohydrodynamic (MHD) turbulence simulation with different relative levels of turbulence amplitude, we investigate and compare the scaling of multi-order magnetic structure functions and magnetic probability distribution functions (PDFs) as well as their dependence on the direction of the local field. The numerical results show that for the case of large-amplitude MHD turbulence, the multi-order structure functions display a multifractal scaling at all angles to the local magnetic field, with PDFs deviating significantly from the Gaussian distribution and a flatness larger than 3 at all angles. In contrast, for the case of small-amplitude MHD turbulence, the multi-order structure functions and PDFs have different features in the quasi-parallel and quasi-perpendicular directions: a monofractal scaling and Gaussian-like distribution in the former, and a conversion of a monofractal scaling and Gaussian-like distribution into a multifractal scaling and non-Gaussian tail distribution in the latter. These results hint that when intermittencies are abundant and intense, the multifractal scaling in the structure functions can appear even if it is in the quasi-parallel direction; otherwise, the monofractal scaling in the structure functions remains even if it is in the quasi-perpendicular direction.

Conceptual design analysis of an MHD power conversion system for droplet-vapor core reactors. Final report

International Nuclear Information System (INIS)

Anghaie, S.; Saraph, G.

1995-01-01

A nuclear driven magnetohydrodynamic (MHD) generator system is proposed for the space nuclear applications of few hundreds of megawatts. The MHD generator is coupled to a vapor-droplet core reactor that delivers partially ionized fissioning plasma at temperatures in range of 3,000 to 4,000 K. A detailed MHD model is developed to analyze the basic electrodynamics phenomena and to perform the design analysis of the nuclear driven MHD generator. An incompressible quasi one dimensional model is also developed to perform parametric analyses

An Optimal Homotopy Asymptotic Approach Applied to Nonlinear MHD Jeffery-Hamel Flow

Directory of Open Access Journals (Sweden)

Vasile Marinca

2011-01-01

Full Text Available A simple and effective procedure is employed to propose a new analytic approximate solution for nonlinear MHD Jeffery-Hamel flow. This technique called the Optimal Homotopy Asymptotic Method (OHAM does not depend upon any small/large parameters and provides us with a convenient way to control the convergence of the solution. The examples given in this paper lead to the conclusion that the accuracy of the obtained results is growing along with increasing the number of constants in the auxiliary function, which are determined using a computer technique. The results obtained through the proposed method are in very good agreement with the numerical results.

Regular shock refraction in planar ideal MHD

International Nuclear Information System (INIS)

Delmont, P; Keppens, R

2010-01-01

We study the classical problem of planar shock refraction at an oblique density discontinuity, separating two gases at rest, in planar ideal (magneto)hydrodynamics. In the hydrodynamical case, 3 signals arise and the interface becomes Richtmyer-Meshkov unstable due to vorticity deposition on the shocked contact. In the magnetohydrodynamical case, on the other hand, when the normal component of the magnetic field does not vanish, 5 signals will arise. The interface then typically remains stable, since the Rankine-Hugoniot jump conditions in ideal MHD do not allow for vorticity deposition on a contact discontinuity. We present an exact Riemann solver based solution strategy to describe the initial self similar refraction phase. Using grid-adaptive MHD simulations, we show that after reflection from the top wall, the interface remains stable.

Unsuspected organic disease in chronic schizophrenia demonstrated by computed tomography

International Nuclear Information System (INIS)

Cunningham Owens, D.G.; Johnstone, E.C.; Bydder, G.M.; Kreel, L.

1980-01-01

Unsuspected intracranial pathology was demonstrated in 12 of 136 chronic schizophrenic patients examined by computed tomography (CT). Seven cases of cerebral infarction were found, and one each of porencephalic cyst, meningioma, cystic enlargement of the pineal body, and two of subdural haematoma. Attention is drawn to the value of CT in demonstrating organic disease in schizophrenia. (author)

MHD Flows in Compact Astrophysical Objects Accretion, Winds and Jets

CERN Document Server

Beskin, Vasily S

2010-01-01

Accretion flows, winds and jets of compact astrophysical objects and stars are generally described within the framework of hydrodynamical and magnetohydrodynamical (MHD) flows. Analytical analysis of the problem provides profound physical insights, which are essential for interpreting and understanding the results of numerical simulations. Providing such a physical understanding of MHD Flows in Compact Astrophysical Objects is the main goal of this book, which is an updated translation of a successful Russian graduate textbook. The book provides the first detailed introduction into the method of the Grad-Shafranov equation, describing analytically the very broad class of hydrodynamical and MHD flows. It starts with the classical examples of hydrodynamical accretion onto relativistic and nonrelativistic objects. The force-free limit of the Grad-Shafranov equation allows us to analyze in detail the physics of the magnetospheres of radio pulsars and black holes, including the Blandford-Znajek process of energy e...

Numerical study of the axisymmetric ideal MHD stability of Extrap

International Nuclear Information System (INIS)

Benda, M.

1993-04-01

A numerical study of the free-boundary axisymmetric (n=0) ideal magnetohydrodynamical (MHD) motions of the Extrap device is presented. The dependence of stability on current profiles in the plasma and currents in the external conductors is investigated. Results are shown for linear growth-rates and nonlinear saturation amplitudes and their dependence on plasma radius as well as on the conducting shell radius. A method combined of two different algorithms has been developed and tested. The interior region of the plasma is simulated by means of a Lagrangian Finite Element Method (FEM) for ideal magnetohydrodynamics, The method is based on a nonlinear radiation principle for the Lagrangian description of ideal MHD. The Boundary Element Method (BEM) is used together with the Lagrangian FEM to simulate nonlinear motion of an ideal MHD plasma behaviour in a vacuum region under the influence of external magnetic fields. 31 refs

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

Directory of Open Access Journals (Sweden)

N. V. Erkaev

2002-01-01

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

Neoclassical MHD equilibria with ohmic current

International Nuclear Information System (INIS)

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

1989-01-01

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

Resistive MHD studies of TFTR discharges

International Nuclear Information System (INIS)

Hughes, M.H.; Phillips, M.W.; Sabbagh, S.A.; Budny, R.V.

1991-01-01

MHD instabilities, thought to be resistive in character, are frequently observed in the supershot operating regime of TFTR (var-epsilon β p ≤ 0.7). These instabilities are always accompanied by substantial degradation of the confinement. Similarly of interest are recent experiments at much larger β p (var-epsilon β p ≤ 1.6), achieved through ramping the current during the beam heating phase of the discharge. In this latter regime the confinement can exceed three times the corresponding L-mode value and the β value normalized to I/aB can be as large as 4.7. Representative discharges from each of these operating regimes have been analyzed using a linear resistive MHD stability code with equilibrium pressure and q profiles obtained initially from the TRANSP analysis code. The main difference between the two types of discharge, as far as stability is concerned is shown to be the shape of the current density profile. The sensitivity to the assumed parameters is discussed. 1 ref

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

International Nuclear Information System (INIS)

Vakilian, M.

1976-02-01

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

HIDENEK: an implicit particle simulation of kinetic-MHD phenomena in three-dimensional plasmas

International Nuclear Information System (INIS)

Tanaka, Motohiko.

1993-05-01

An advanced 'kinetic-MHD' simulation method and its applications to plasma physics are given in this lecture. This method is quite suitable for studying strong nonlinear, kinetic processes associated with large space-scale, low-frequency electromagnetic phenomena of plasmas. A full set of the Maxwell equations, and the Newton-Lorentz equations of motion for particle ions and guiding-center electrons are adopted. In order to retain only the low-frequency waves and instabilities, implicit particle-field equations are derived. The present implicit-particle method is proved to reproduce the MHD eigenmodes such as Alfven, magnetosonic and kinetic Alfven waves in a thermally near-equilibrium plasma. In the second part of the lecture, several physics applications are shown. These include not only the growth of the instabilities of beam ions against the background plasmas and helical kink of the current, but they also demonstrate nonlinear results such as pitch-angle scattering of the ions. Recent progress in the simulation of the Kelvin-Helmholtz instability is also presented with a special emphasis on the mixing of plasma particles. (author)

Computational-physics program of the National MFE Computer Center

International Nuclear Information System (INIS)

Mirin, A.A.

1982-02-01

The computational physics group is ivolved in several areas of fusion research. One main area is the application of multidimensional Fokker-Planck, transport and combined Fokker-Planck/transport codes to both toroidal and mirror devices. Another major area is the investigation of linear and nonlinear resistive magnetohydrodynamics in two and three dimensions, with applications to all types of fusion devices. The MHD work is often coupled with the task of numerically generating equilibria which model experimental devices. In addition to these computational physics studies, investigations of more efficient numerical algorithms are being carried out

Intermittency in MHD turbulence and coronal nanoflares modelling

Directory of Open Access Journals (Sweden)

P. Veltri

2005-01-01

Full Text Available High resolution numerical simulations, solar wind data analysis, and measurements at the edges of laboratory plasma devices have allowed for a huge progress in our understanding of MHD turbulence. The high resolution of solar wind measurements has allowed to characterize the intermittency observed at small scales. We are now able to set up a consistent and convincing view of the main properties of MHD turbulence, which in turn constitutes an extremely efficient tool in understanding the behaviour of turbulent plasmas, like those in solar corona, where in situ observations are not available. Using this knowledge a model to describe injection, due to foot-point motions, storage and dissipation of MHD turbulence in coronal loops, is built where we assume strong longitudinal magnetic field, low beta and high aspect ratio, which allows us to use the set of reduced MHD equations (RMHD. The model is based on a shell technique in the wave vector space orthogonal to the strong magnetic field, while the dependence on the longitudinal coordinate is preserved. Numerical simulations show that injected energy is efficiently stored in the loop where a significant level of magnetic and velocity fluctuations is obtained. Nonlinear interactions give rise to an energy cascade towards smaller scales where energy is dissipated in an intermittent fashion. Due to the strong longitudinal magnetic field, dissipative structures propagate along the loop, with the typical speed of the Alfvén waves. The statistical analysis on the intermittent dissipative events compares well with all observed properties of nanoflare emission statistics. Moreover the recent observations of non thermal velocity measurements during flare occurrence are well described by the numerical results of the simulation model. All these results naturally emerge from the model dynamical evolution without any need of an ad-hoc hypothesis.

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

International Nuclear Information System (INIS)

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

1989-01-01

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

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

International Nuclear Information System (INIS)

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

1994-01-01

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

Further validation of liquid metal MHD code for unstructured grid based on OpenFOAM

Energy Technology Data Exchange (ETDEWEB)

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

2015-11-15

Highlights: • Specific correction scheme has been adopted to revise the calculating result for non-orthogonal meshes. • The developed MHD code based on OpenFOAM platform has been validated by benchmark cases under uniform and non-uniform magnetic field in round and rectangular ducts. • ALEX experimental results have been used to validate the MHD code based on OpenFOAM. - Abstract: In fusion liquid metal blankets, complex geometries involving contractions, expansions, bends, manifolds are very common. The characteristics of liquid metal flow in these geometries are significant. In order to extend the magnetohydrodynamic (MHD) solver developed on OpenFOAM platform to be applied in the complex geometry, the MHD solver based on unstructured meshes has been implemented. The adoption of non-orthogonal correction techniques in the solver makes it possible to process the non-orthogonal meshes in complex geometries. The present paper focused on the validation of the code under critical conditions. An analytical solution benchmark case and two experimental benchmark cases were conducted to validate the code. Benchmark case I is MHD flow in a circular pipe with arbitrary electric conductivity of the walls in a uniform magnetic field. Benchmark cases II and III are experimental cases of 3D laminar steady MHD flow under fringing magnetic field. In all these cases, the numerical results match well with the benchmark cases.

Further validation of liquid metal MHD code for unstructured grid based on OpenFOAM

International Nuclear Information System (INIS)

Feng, Jingchao; Chen, Hongli; He, Qingyun; Ye, Minyou

2015-01-01

Highlights: • Specific correction scheme has been adopted to revise the calculating result for non-orthogonal meshes. • The developed MHD code based on OpenFOAM platform has been validated by benchmark cases under uniform and non-uniform magnetic field in round and rectangular ducts. • ALEX experimental results have been used to validate the MHD code based on OpenFOAM. - Abstract: In fusion liquid metal blankets, complex geometries involving contractions, expansions, bends, manifolds are very common. The characteristics of liquid metal flow in these geometries are significant. In order to extend the magnetohydrodynamic (MHD) solver developed on OpenFOAM platform to be applied in the complex geometry, the MHD solver based on unstructured meshes has been implemented. The adoption of non-orthogonal correction techniques in the solver makes it possible to process the non-orthogonal meshes in complex geometries. The present paper focused on the validation of the code under critical conditions. An analytical solution benchmark case and two experimental benchmark cases were conducted to validate the code. Benchmark case I is MHD flow in a circular pipe with arbitrary electric conductivity of the walls in a uniform magnetic field. Benchmark cases II and III are experimental cases of 3D laminar steady MHD flow under fringing magnetic field. In all these cases, the numerical results match well with the benchmark cases.

MHD seed recovery and regeneration, Phase II. Final report

Energy Technology Data Exchange (ETDEWEB)

1994-10-01

This final report summarizes the work performed by the Space and Technology Division of the TRW Space and Electronics Group for the U.S. Department of Energy, Pittsburgh Energy Technology Center for the Econoseed process. This process involves the economical recovery and regeneration of potassium seed used in the MHD channel. The contract period of performance extended from 1987 through 1994 and was divided into two phases. The Phase II test results are the subject of this Final Report. However, the Phase I test results are presented in summary form in Section 2.3 of this Final Report. The Econoseed process involves the treatment of the potassium sulfate in spent MHD seed with an aqueous calcium formate solution in a continuously stirred reactor system to solubilize, as potassium formate, the potassium content of the seed and to precipitate and recover the sulfate as calcium sulfate. The slurry product from this reaction is centrifuged to separate the calcium sulfate and insoluble seed constituents from the potassium formate solution. The dilute solids-free potassium formate solution is then concentrated in an evaporator. The concentrated potassium formate product is a liquid which can be recycled as a spray into the MHD channel. Calcium formate is the seed regenerant used in the Econoseed process. Since calcium formate is produced in the United States in relatively small quantities, a new route to the continuous production of large quantities of calcium formate needed to support an MHD power industry was investigated. This route involves the reaction of carbon monoxide gas with lime solids in an aqueous medium.

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

International Nuclear Information System (INIS)

Zhang, Xiujie; Pan, Chuanjie; Xu, Zengyu

2013-01-01

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

3D nonlinear MHD simulations of ultra-low q plasmas

International Nuclear Information System (INIS)

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

2008-01-01

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

Calculation of three-dimensional MHD equilibria with islands and stochastic regions

International Nuclear Information System (INIS)

Reiman, A.; Greenside, H.

1986-08-01

A three-dimensional MHD equilibrium code is described that does not assume the existence of good surfaces. Given an initial guess for the magnetic field, the code proceeds by calculating the pressure-driven current and then by updating the field using Ampere's law. The numerical algorithm to solve the magnetic differential equation for the pressure-driven current is described, and demonstrated for model fields having islands and stochastic regions. The numerical algorithm which solves Ampere's law in three dimensions is also described. Finally, the convergence of the code is illustrated for a particular stellarator equilibrium with no large islands

Elms: MHD Instabilities at the transport barrier

Energy Technology Data Exchange (ETDEWEB)

Huysmans, G.T.A

2005-07-01

Significant progress has been made in recent years both on the experimental characterisation of ELMs (edge localized modes) and the theory and modelling of ELMs. The observed maximum pressure gradient is in good agreement with the calculated ideal MHD stability limits due to peeling-ballooning modes. The dependence on plasma current and plasma shape are also reproduced by the ideal MHD model. It will be a challenge to verify experimentally the influence of the extensions to the ideal MHD theory such as the possibly incomplete diamagnetic stabilisation, the influence of shear flow, finite resistivity or the stabilizing influence of the separatrix on peeling modes. The observations of the filamentary structures find their explanation in the theory and simulations of the early non-linear phase of the evolution of ballooning modes. One of the remaining open questions is what determines the size of the ELM and its duration. This is related to the loss mechanism of energy and density. Some heuristic descriptions of possible mechanisms have been proposed in literature but none of the models so far makes quantitative predictions on the ELM size. Also the numerical simulations are not yet advanced to the point where the full ELM crash can be modelled. The theory and simulations of the ELMs are necessary to decide between the possible parameters, such as the collisionality or the parallel transport time, that are proposed for the extrapolation of ELM sizes to ITER.

Elms: MHD Instabilities at the transport barrier

International Nuclear Information System (INIS)

Huysmans, G.T.A.

2005-01-01

Significant progress has been made in recent years both on the experimental characterisation of ELMs (edge localized modes) and the theory and modelling of ELMs. The observed maximum pressure gradient is in good agreement with the calculated ideal MHD stability limits due to peeling-ballooning modes. The dependence on plasma current and plasma shape are also reproduced by the ideal MHD model. It will be a challenge to verify experimentally the influence of the extensions to the ideal MHD theory such as the possibly incomplete diamagnetic stabilisation, the influence of shear flow, finite resistivity or the stabilizing influence of the separatrix on peeling modes. The observations of the filamentary structures find their explanation in the theory and simulations of the early non-linear phase of the evolution of ballooning modes. One of the remaining open questions is what determines the size of the ELM and its duration. This is related to the loss mechanism of energy and density. Some heuristic descriptions of possible mechanisms have been proposed in literature but none of the models so far makes quantitative predictions on the ELM size. Also the numerical simulations are not yet advanced to the point where the full ELM crash can be modelled. The theory and simulations of the ELMs are necessary to decide between the possible parameters, such as the collisionality or the parallel transport time, that are proposed for the extrapolation of ELM sizes to ITER

Coal-fired magnetohydrodynamic (MHD) electric power generation

International Nuclear Information System (INIS)

Sens, P.F.

1992-01-01

Since 1986 Directorate-General XII 'Science, Research and Development' of the Commission of the European Communities has kept a watching brief on the development of coal-fired magnetohydrodynamic (MHD) electric power generation from the 'solid fuels' section of its non-nuclear energy R and D programme. It established, in 1987, the Faraday Working Group (FWG) to assess the development status of coal-fired MHD and to evaluate its potential contribution to the future electricity production in the Community. The FWG expressed as its opinion, at the end of 1987, that in sufficient data were available to justify a final answer to the question about MHD's potential contribution to future electricity production and recommended that studies be undertaken in three areas; (i) the lifetime of the generator, (ii) cost and performance of direct air preheating, (iii) cost and efficiency of seed recovery/reprocessing. These studies were contracted and results were presented in the extended FWG meeting on 15 November 1990, for an audience of about 70 people. The present volume contains the proceedings of this meeting. The introduction describes the reasons for establishing the FWG, its activities and the content of its extended meeting followed by the summary of the discussions and the concluding remarks of this meeting. The main part of the volume consists of the text either of the oral presentations during the meeting or of the final reports resulting from the studies under contract

Construction and initial operation of MHD PbLi facility at UCLA

Energy Technology Data Exchange (ETDEWEB)

Smolentsev, S., E-mail: sergey@fusion.ucla.edu; Li, F.-C.; Morley, N.; Ueki, Y.; Abdou, M.; Sketchley, T.

2013-06-15

Highlights: • New MHD PbLi loop has been constructed and tested at UCLA. • Pressure diagnostics system has been developed and successfully tested. • Ultrasound Doppler velocimeter is tested as velocity diagnostics. • Experiments on pressure drop reduction have been performed. • Experiments on MHD flow in a duct with SiC flow channel insert are underway. -- Abstract: A magnetohydrodynamic flow facility MaPLE (Magnetohydrodynamic PbLi Experiment) that utilizes molten eutectic alloy lead–lithium (PbLi) as working fluid has been constructed and tested at University of California, Los Angeles. The loop operation parameters are: maximum magnetic field 1.8 T, PbLi temperature up to 350 °C, maximum PbLi flow rate with/without a magnetic field 15/50 l/min, maximum pressure head 0.15 MPa. The paper describes the loop itself and its major components, basic operation procedures, experience of handling PbLi, initial loop testing, flow diagnostics and current and near-future experiments. The obtained test results of the loop and its components have demonstrated that the new facility is fully functioning and ready for experimental studies of magnetohydrodynamic, heat and mass transfer phenomena in PbLi flows and also can be used in mock up testing in conditions relevant to fusion applications.

An analytical demonstration of coupling schemes between magnetohydrodynamic codes and eddy current codes

International Nuclear Information System (INIS)

Liu Yueqiang; Albanese, R.; Rubinacci, G.; Portone, A.; Villone, F.

2008-01-01

In order to model a magnetohydrodynamic (MHD) instability that strongly couples to external conducting structures (walls and/or coils) in a fusion device, it is often necessary to combine a MHD code solving for the plasma response, with an eddy current code computing the fields and currents of conductors. We present a rigorous proof of the coupling schemes between these two types of codes. One of the coupling schemes has been introduced and implemented in the CARMA code [R. Albanese, Y. Q. Liu, A. Portone, G. Rubinacci, and F. Villone, IEEE Trans. Magn. 44, 1654 (2008); A. Portone, F. Villone, Y. Q. Liu, R. Albanese, and G. Rubinacci, Plasma Phys. Controlled Fusion 50, 085004 (2008)] that couples the MHD code MARS-F[Y. Q. Liu, A. Bondeson, C. M. Fransson, B. Lennartson, and C. Breitholtz, Phys. Plasmas 7, 3681 (2000)] and the eddy current code CARIDDI[R. Albanese and G. Rubinacci, Adv. Imaging Electron Phys. 102, 1 (1998)]. While the coupling schemes are described for a general toroidal geometry, we give the analytical proof for a cylindrical plasma.

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

Science.gov (United States)

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.

Alpha particle effects on MHD ballooning

International Nuclear Information System (INIS)

1991-01-01

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

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

International Nuclear Information System (INIS)

Toi, K.

2002-01-01

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

Performance of the CNEN MHD Blow-Down Loop Facility

Energy Technology Data Exchange (ETDEWEB)

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

1968-11-15

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

Kinetic Modifications to MHD Phenomena in Toroidal Plasmas

International Nuclear Information System (INIS)

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

2004-01-01

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

Calculation code NIRVANA for free boundary MHD equilibrium

International Nuclear Information System (INIS)

Ninomiya, Hiromasa; Suzuki, Yasuo; Kameari, Akihisa

1975-03-01

The calculation method and code of solving the free boundary problem for MHD equilibrium has been developed. Usage of the code ''NIRVANA'' is described. The toroidal plasma current density determined as a function of the flux function PSI is substituted by a group of the ring currents, whereby the equation of MHD equilibrium is transformed into an integral equation. Either of the two iterative methods is chosen to solve the integral equation, depending on the assumptions made of the plasma surface points. Calculation of the magnetic field configurations is possible when the plasma surface coincides self-consistently with the magnetic flux including the separatrix points. The code is usable in calculation of the circular or non-circular shell-less Tokamak equilibrium. (auth.)

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

International Nuclear Information System (INIS)

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

1979-10-01

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

Numerical Simulation of 3D Viscous MHD Flows

National Research Council Canada - National Science Library

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

2003-01-01

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

Temperature oscillating regimes in Tore Supra diagnosed by MHD activity

International Nuclear Information System (INIS)

Maget, P.; Imbeaux, F.; Giruzzi, G.; Udintsev, V.S.; Huysmans, G.T.A.; Segui, J.-L.; Goniche, M.; Moreau, Ph.; Sabot, R.; Garbet, X.

2006-01-01

This paper describes what we can learn on the regimes of spontaneous electron temperature oscillations discovered in Tore Supra from the analysis of MHD activity. Since the first observations of this oscillating behaviour of plasma equilibrium, and its interpretation as a predator-prey system involving lower hybrid waves power deposition and electron confinement, analysis of MHD modes has confirmed the reality of safety factor profile oscillations. This points towards the importance of rational values of the safety factor in the transition to transport barriers in reversed magnetic shear plasmas

The pedagogical toolbox: computer-generated visual displays, classroom demonstration, and lecture.

Science.gov (United States)

Bockoven, Jerry

2004-06-01

This analogue study compared the effectiveness of computer-generated visual displays, classroom demonstration, and traditional lecture as methods of instruction used to teach neuronal structure and processes. Randomly assigned 116 undergraduate students participated in 1 of 3 classrooms in which they experienced the same content but different teaching approaches presented by 3 different student-instructors. Then participants completed a survey of their subjective reactions and a measure of factual information designed to evaluate objective learning outcomes. Participants repeated this factual measure 5 wk. later. Results call into question the use of classroom demonstration methods as well as the trend towards devaluing traditional lecture in favor of computer-generated visual display.

Present state of the theory of a MHD-dynamo

Energy Technology Data Exchange (ETDEWEB)

Soward, A M; Roberts, P H

1976-01-01

A review is given of the state of the theory of a MHD-dynamo, that is, the theory of self-excited magnetic fields in homogeneous moving liquids. A description is given of two basic approaches-the turbulent dynamos of Steinbeck, Krause and Redler and the high-conductivity dynamo of Braginski, and a look is also taken at the relation between these dynamos. Finally a look is taken at the results of recent studies of the total problem of a MHD-dynamo, that is, at the results of recent attempts to solve the electro- and hydrodynamic equations and to obtain self-excited fields. 6 figs., 122 ref. (SJR)

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

International Nuclear Information System (INIS)

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

2009-01-01

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

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

International Nuclear Information System (INIS)

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

2005-01-01

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

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

Science.gov (United States)

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

2013-08-01

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

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Chemical Recovery of Energy in a Combined MHD-Steam Power Station; Recuperation Chimique d'Energie dans une Centrale Combinee MHD-Vapeur

Energy Technology Data Exchange (ETDEWEB)

Carrasse, J. [Societe Alsthom, Paris (France)

1966-12-15

This paper studies the energetic and chemical aspects of the operation of a combined MHD-steam power station using the combustion gases from a fossil fuel in an open circuit with potassium seeding. It describes a process for the recovery of energy by endothermal chemical gasification of the fuel. The author first recalls briefly the thermal and chemical conditions to be met throughout the length of the gas flow and points out that it is vital to ensure as much recycling of energy as possible from below to above the MHD generator, at the expense of the conventional power station located further on in the system. The paper then describes the various processes intended to ensure the thermal operating conditions required, including preheating of the air, oxygen enrichment etc. The last part of the paper, which goes into greater detail while taking the foregoing considerations into account, explains the principle and various feasible methods of application of a process at present under study and experimentation. In this process some of the heat energy of the gases discharged from the MHD duct is recycled, partly in chemical form and partly as a limited amount of gas preheat. For this purpose the fuel, mixed with oxidizing agents such as water vapour or carbon dioxide, is gasified, at about 950 Degree-Sign C and after a series of collectively endothermal reactions, into a gas composed mainly of carbon monoxide, hydrogen, nitrogen and excess water vapour and carbon dioxide. It is thus possible to avoid the employment of very high temperature heat exchangers working with seeded gas. The paper stresses the extraction of seeding material, which is simple and can here take place to a great extent in liquid form (fused salts) due to the fact that operation is in the temperature range around 1000 Degree-Sign C. Consideration is finally given to the use after treatment (cooling, extraction of seeding material, absorption of excess H{sub 2}O and CO{sub 2}, compression and re

Effect of Trapped Energetic Ions on MHD Activity in Spherical Tori

International Nuclear Information System (INIS)

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

2002-01-01

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

Ideal MHD Stability Prediction and Required Power for EAST Advanced Scenario

International Nuclear Information System (INIS)

Chen Junjie; Li Guoqiang; Qian Jinping; Liu Zixi

2012-01-01

The Experimental Advanced Superconducting Tokamak (EAST) is the first fully superconducting tokamak with a D-shaped cross-sectional plasma presently in operation. The ideal magnetohydrodynamic (MHD) stability and required power for the EAST advanced tokamak (AT) scenario with negative central shear and double transport barrier (DTB) are investigated. With the equilibrium code TOQ and stability code GATO, the ideal MHD stability is analyzed. It is shown that a moderate ratio of edge transport barriers' (ETB) height to internal transport barriers' (ITBs) height is beneficial to ideal MHD stability. The normalized beta β N limit is about 2.20 (without wall) and 3.70 (with ideal wall). With the scaling law of energy confinement time, the required heating power for EAST AT scenario is calculated. The total heating power P t increases as the toroidal magnetic field B T or the normalized beta β N is increased. (magnetically confined plasma)

Ideal MHD Stability Prediction and Required Power for EAST Advanced Scenario

Science.gov (United States)

Chen, Junjie; Li, Guoqiang; Qian, Jinping; Liu, Zixi

2012-11-01

The Experimental Advanced Superconducting Tokamak (EAST) is the first fully superconducting tokamak with a D-shaped cross-sectional plasma presently in operation. The ideal magnetohydrodynamic (MHD) stability and required power for the EAST advanced tokamak (AT) scenario with negative central shear and double transport barrier (DTB) are investigated. With the equilibrium code TOQ and stability code GATO, the ideal MHD stability is analyzed. It is shown that a moderate ratio of edge transport barriers' (ETB) height to internal transport barriers' (ITBs) height is beneficial to ideal MHD stability. The normalized beta βN limit is about 2.20 (without wall) and 3.70 (with ideal wall). With the scaling law of energy confinement time, the required heating power for EAST AT scenario is calculated. The total heating power Pt increases as the toroidal magnetic field BT or the normalized beta βN is increased.

Annular MHD Physics for Turbojet Energy Bypass

Science.gov (United States)

Schneider, Steven J.

2011-01-01

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

Minamata disease demonstrated by computed tomography

International Nuclear Information System (INIS)

Matsumoto, S.C.; Okajima, T.; Inayoshi, S.; Ueno, H.

1988-01-01

Computed tomography was studied in the patients with Minamata disease, a methylmercury poisoning caused by the ingestion of contaminated sea foods. The characteristic changes in the acquired cases were atrophy of the visual calcarine cortex and of the cerebellar vermis and or hemisphere. Marked atrophy of the calcarine cortex produced the sac-shaped low density areas between the occipital lobes and diffuse and marked cerebellar atrophy with enlargement of the fourth ventricle and cisterns of the posterior fossa produced a shrunken image on CT. Morphometric analysis confirmed these findings. In the fetal cases, the changes on CT were slight and no definite atrophy was demonstrated in either the calcarine cortex or the cerebellum. Morphometric analysis disclosed an increase of size of the middle portions of the lateral ventricle and the third and fourth ventricles. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-15

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

MHD equilibrium and stability in heliotron plasmas

Energy Technology Data Exchange (ETDEWEB)

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

1999-09-01

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

Localized MHD activity near transport barriers in JT-60U and TFTR

International Nuclear Information System (INIS)

Manickam, J.

2001-01-01

Localized MHD activity observed in JT-60U and TFTR near transport barriers with their associated large pressure gradients is investigated. Stability analysis of equilibria modeling the experiments supports an identification of this MHD as being due to an ideal MHD n=1 instability. The appearance of the instability depends on the local pressure gradient, local shear in the q profile and the proximity of rational surfaces where q∼m/n and m and n are the poloidal and toroidal mode numbers respectively. The mode width is shown to depend on the local value of q, and is larger when q is smaller. In addition the role of the edge current density in coupling the internal mode to the plasma edge and of the energetic particles which can drive fishbone like modes is investigated. (author)

Convective heat transfer in MHD channels and its influence on channel performance

International Nuclear Information System (INIS)

Ahluwalia, R.K.; Doss, E.D.

1980-01-01

The limitations of the integral boundary layer methods and the potential of the differential boundary layer method in analyzing MHD channel flows are assessed. The sensitivity of results from the integral method to the parametrization of boundary layer profiles and calculation of wall heat transfer is established. A mixing-length type turbulence model for flow on rough walls is developed and validated by comparison with experimental data. The turbulence model is used in a quasi-three-dimensional boundary layer model to evaluate the influence of wall roughness and pressure gradients on the flow characteristics and performance of MHD channels. The behaviors of skin friction and Stanton number calculated from the analytical model are found to differ considerably from the empirical correlations valid for non-MHD flows without pressure gradients

Divergence-free MHD Simulations with the HERACLES Code

Directory of Open Access Journals (Sweden)

Vides J.

2013-12-01

Full Text Available Numerical simulations of the magnetohydrodynamics (MHD equations have played a significant role in plasma research over the years. The need of obtaining physical and stable solutions to these equations has led to the development of several schemes, all requiring to satisfy and preserve the divergence constraint of the magnetic field numerically. In this paper, we aim to show the importance of maintaining this constraint numerically. We investigate in particular the hyperbolic divergence cleaning technique applied to the ideal MHD equations on a collocated grid and compare it to the constrained transport technique that uses a staggered grid to maintain the property. The methods are implemented in the software HERACLES and several numerical tests are presented, where the robustness and accuracy of the different schemes can be directly compared.

United States Superconducting MHD Magnet Technology Development Program

International Nuclear Information System (INIS)

Dawson, A.M.; Marston, P.G.; Thome, R.J.; Iwasa, Y.; Tarrh, J.M.

1981-01-01

A three-faceted program supported by the U.S. Dep of Energy is described. These facets include basic technology development, technology transfer and construction by industry of magnets for the national MHD program. The program includes the maintenance of a large component test facility; investigation of superconductor stability and structural behavior; measurements of materials' properties at low temperatures; structural design optimization; analytical code development; cryogenic systems and power supply design. The technology transfer program is designed to bring results of technology development and design and construction effort to the entire superconducting magnet community. The magnet procurement program is responsible for developing conceptual designs of magnets needed for the national MHD program, for issuing requests for quotation, selecting vendors and supervising design, construction, installation and test of these systems. 9 refs

G-computation demonstration in causal mediation analysis

International Nuclear Information System (INIS)

Wang, Aolin; Arah, Onyebuchi A.

2015-01-01

Recent work has considerably advanced the definition, identification and estimation of controlled direct, and natural direct and indirect effects in causal mediation analysis. Despite the various estimation methods and statistical routines being developed, a unified approach for effect estimation under different effect decomposition scenarios is still needed for epidemiologic research. G-computation offers such unification and has been used for total effect and joint controlled direct effect estimation settings, involving different types of exposure and outcome variables. In this study, we demonstrate the utility of parametric g-computation in estimating various components of the total effect, including (1) natural direct and indirect effects, (2) standard and stochastic controlled direct effects, and (3) reference and mediated interaction effects, using Monte Carlo simulations in standard statistical software. For each study subject, we estimated their nested potential outcomes corresponding to the (mediated) effects of an intervention on the exposure wherein the mediator was allowed to attain the value it would have under a possible counterfactual exposure intervention, under a pre-specified distribution of the mediator independent of any causes, or under a fixed controlled value. A final regression of the potential outcome on the exposure intervention variable was used to compute point estimates and bootstrap was used to obtain confidence intervals. Through contrasting different potential outcomes, this analytical framework provides an intuitive way of estimating effects under the recently introduced 3- and 4-way effect decomposition. This framework can be extended to complex multivariable and longitudinal mediation settings

Generalized similarity method in unsteady two-dimensional MHD ...

African Journals Online (AJOL)

user

International Journal of Engineering, Science and Technology. Vol. 1, No. 1, 2009 ... temperature two-dimensional MHD laminar boundary layer of incompressible fluid. ...... Φ η is Blasius solution for stationary boundary layer on the plate,. ( ). 0.

Analyses of the Photospheric Magnetic Dynamics in Solar Active Region 11117 Using an Advanced CESE-MHD Model

Energy Technology Data Exchange (ETDEWEB)

Jiang, Chaowei [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL (United States); Wu, Shi T. [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL (United States); Department of Mechanical and Aerospace Engineering, The University of Alabama in Huntsville, AL (United States); Feng, Xueshang, E-mail: cwjiang@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China)

2016-05-10

In this study, the photospheric vector magnetograms obtained by Helioseismic and Magnetic Imager on-board the Solar Dynamics Observatory are used as boundary conditions for a CESE-MHD model to investigate some photosphere characteristics around the time of a confined flare in solar active region NOAA AR 11117. We report our attempt of characterizing a more realistic solar atmosphere by including a plasma with temperature stratified from the photosphere to the corona in the CESE-MHD model. The resulted photospheric transverse flow is comparable to the apparent movements of the magnetic flux features that demonstrates shearing and rotations. We calculated the relevant parameters such as the magnetic energy flux and helicity flux, and with analysis of these parameters, we find that magnetic non-potentiality is transported across the photosphere into the corona in the simulated time interval, which might provide a favorable condition for producing the flare.

Assessment of ionospheric Joule heating by GUMICS-4 MHD simulation, AMIE, and satellite-based statistics: towards a synthesis

Directory of Open Access Journals (Sweden)

M. Palmroth

2005-09-01

Full Text Available We investigate the Northern Hemisphere Joule heating from several observational and computational sources with the purpose of calibrating a previously identified functional dependence between solar wind parameters and ionospheric total energy consumption computed from a global magnetohydrodynamic (MHD simulation (Grand Unified Magnetosphere Ionosphere Coupling Simulation, GUMICS-4. In this paper, the calibration focuses on determining the amount and temporal characteristics of Northern Hemisphere Joule heating. Joule heating during a substorm is estimated from global observations, including electric fields provided by Super Dual Auroral Network (SuperDARN and Pedersen conductances given by the ultraviolet (UV and X-ray imagers on board the Polar satellite. Furthermore, Joule heating is assessed from several activity index proxies, large statistical surveys, assimilative data methods (AMIE, and the global MHD simulation GUMICS-4. We show that the temporal and spatial variation of the Joule heating computed from the GUMICS-4 simulation is consistent with observational and statistical methods. However, the different observational methods do not give a consistent estimate for the magnitude of the global Joule heating. We suggest that multiplying the GUMICS-4 total Joule heating by a factor of 10 approximates the observed Joule heating reasonably well. The lesser amount of Joule heating in GUMICS-4 is essentially caused by weaker Region 2 currents and polar cap potentials. We also show by theoretical arguments that multiplying independent measurements of averaged electric fields and Pedersen conductances yields an overestimation of Joule heating.

Keywords. Ionosphere (Auroral ionosphere; Modeling and forecasting; Electric fields and currents

On the stability of dissipative MHD equilibria

International Nuclear Information System (INIS)

Teichmann, J.

1979-04-01

The global stability of stationary equilibria of dissipative MHD is studied uisng the direct Liapunov method. Sufficient and necessary conditions for stability of the linearized Euler-Lagrangian system with the full dissipative operators are given. The case of the two-fluid isentropic flow is discussed. (orig.)

Exact solutions for MHD flow of couple stress fluid with heat transfer

Directory of Open Access Journals (Sweden)

Najeeb Alam Khan

2016-01-01

Full Text Available This paper aims at presenting exact solutions for MHD flow of couple stress fluid with heat transfer. The governing partial differential equations (PDEs for an incompressible MHD flow of couple stress fluid are reduced to ordinary differential equations by employing wave parameter. The methodology is implemented for linearizing the flow equations without extra transformation and restrictive assumptions. Comparison is made with the result obtained previously.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Variational Integration for Ideal MHD with Built-in Advection Equations

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yao [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Qin, Hong [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Burby, J. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Bhattacharjee, A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

2014-08-05

Newcomb's Lagrangian for ideal MHD in Lagrangian labeling is discretized using discrete exterior calculus. Variational integrators for ideal MHD are derived thereafter. Besides being symplectic and momentum preserving, the schemes inherit built-in advection equations from Newcomb's formulation, and therefore avoid solving them and the accompanying error and dissipation. We implement the method in 2D and show that numerical reconnection does not take place when singular current sheets are present. We then apply it to studying the dynamics of the ideal coalescence instability with multiple islands. The relaxed equilibrium state with embedded current sheets is obtained numerically.

Modeling of Low Frequency MHD Induced Beam Ion Transport In NSTX

International Nuclear Information System (INIS)

Gorelenkov, N.N.; Medley, S.S.

2004-01-01

Beam ion transport in the presence of low frequency MHD activity in National Spherical Tokamak Experiment (NSTX) plasma is modeled numerically and analyzed theoretically in order to understand basic underlying physical mechanisms responsible for the observed fast ion redistribution and losses. Numerical modeling of the beam ions flux into the NPA in NSTX shows that after the onset of low frequency MHD activity high energy part of beam ion distribution, E b > 40keV, is redistributed radially due to stochastic diffusion. Such diffusion is caused by high order harmonics of the transit frequency resonance overlap in the phase space. Large drift orbit radial width induces such high order resonances. Characteristic confinement time is deduced from the measured NPA energy spectrum and is typically ∼ 4msec. Considered MHD activity may induce losses on the order of 10% at the internal magnetic field perturbation (delta)B/B = Ο (10 -3 ), which is comparable to the prompt orbit losses

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

Science.gov (United States)

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

International Nuclear Information System (INIS)

Medley, S.S.; Gorelenkov, N.N.; Andre, R.; Bell, R.E.; Darrow, D.S.; Fredrickson, E.D.; Kaye, S.M.; LeBlanc, B.P.; Roquemore, A.L.

2004-01-01

MHD-induced energetic ion loss in neutral-beam-heated H-mode [high-confinement mode] discharges in NSTX [National Spherical Torus Experiment] is discussed. A rich variety of energetic ion behavior resulting from magnetohydrodynamic (MHD) activity is observed in the NSTX using a horizontally scanning Neutral Particle Analyzer (NPA) whose sightline views across the three co-injected neutral beams. For example, onset of an n = 2 mode leads to relatively slow decay of the energetic ion population (E ∼ 10-100 keV) and consequently the neutron yield. The effect of reconnection events, sawteeth, and bounce fishbones differs from that observed for low-n, low-frequency, tearing-type MHD modes. In this case, prompt loss of the energetic ion population occurs on a time scale of less than or equal to 1 ms and a precipitous drop in the neutron yield occurs. This paper focuses on MHD-induced ion loss during H-mode operation in NSTX. After H-mode onset, the NPA charge-exchange spectrum usually exhibits a significant loss of energetic ions only for E > E(sub)b/2 where E(sub)b is the beam injection energy. The magnitude of the energetic ion loss was observed to decrease with increasing tangency radius, R(sub)tan, of the NPA sightline, increasing toroidal field, B(sub)T, and increasing neutral-beam injection energy, E(sub)b. TRANSP modeling suggests that MHD-induced ion loss is enhanced during H-mode operation due to an evolution of the q and beam deposition profiles that feeds both passing and trapped ions into the region of low-n MHD activity. ORBIT code analysis of particle interaction with a model magnetic perturbation supported the energy selectivity of the MHD-induced loss observed in the NPA measurements. Transport analysis with the TRANSP code using a fast-ion diffusion tool to emulate the observed MHD-induced energetic ion loss showed significant modifications of the neutral- beam heating as well as the power balance, thermal diffusivities, energy confinement times, and

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

Energy Technology Data Exchange (ETDEWEB)

S.S. Medley; N.N. Gorelenkov; R. Andre; R.E. Bell; D.S. Darrow; E.D. Fredrickson; S.M. Kaye; B.P. LeBlanc; A.L. Roquemore; and the NSTX Team

2004-03-15

MHD-induced energetic ion loss in neutral-beam-heated H-mode [high-confinement mode] discharges in NSTX [National Spherical Torus Experiment] is discussed. A rich variety of energetic ion behavior resulting from magnetohydrodynamic (MHD) activity is observed in the NSTX using a horizontally scanning Neutral Particle Analyzer (NPA) whose sightline views across the three co-injected neutral beams. For example, onset of an n = 2 mode leads to relatively slow decay of the energetic ion population (E {approx} 10-100 keV) and consequently the neutron yield. The effect of reconnection events, sawteeth, and bounce fishbones differs from that observed for low-n, low-frequency, tearing-type MHD modes. In this case, prompt loss of the energetic ion population occurs on a time scale of less than or equal to 1 ms and a precipitous drop in the neutron yield occurs. This paper focuses on MHD-induced ion loss during H-mode operation in NSTX. After H-mode onset, the NPA charge-exchange spectrum usually exhibits a significant loss of energetic ions only for E > E(sub)b/2 where E(sub)b is the beam injection energy. The magnitude of the energetic ion loss was observed to decrease with increasing tangency radius, R(sub)tan, of the NPA sightline, increasing toroidal field, B(sub)T, and increasing neutral-beam injection energy, E(sub)b. TRANSP modeling suggests that MHD-induced ion loss is enhanced during H-mode operation due to an evolution of the q and beam deposition profiles that feeds both passing and trapped ions into the region of low-n MHD activity. ORBIT code analysis of particle interaction with a model magnetic perturbation supported the energy selectivity of the MHD-induced loss observed in the NPA measurements. Transport analysis with the TRANSP code using a fast-ion diffusion tool to emulate the observed MHD-induced energetic ion loss showed significant modifications of the neutral- beam heating as well as the power balance, thermal diffusivities, energy confinement times

Nonlinear MHD Waves in a Prominence Foot

Science.gov (United States)

Ofman, L.; Knizhnik, K.; Kucera, T.; Schmieder, B.

2015-11-01

We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ˜ δn/n). The waves are evident as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5-11 minutes and wavelengths <2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with the THEMIS instrument and was found to be 5-14 G. For the typical prominence density the corresponding fast magnetosonic speed is ˜20 km s-1, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

NONLINEAR MHD WAVES IN A PROMINENCE FOOT

Energy Technology Data Exchange (ETDEWEB)

Ofman, L. [Catholic University of America, Washington, DC 20064 (United States); Knizhnik, K.; Kucera, T. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Schmieder, B. [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris-Diderot, Sorbonne Paris Cit, 5 place Jules Janssen, F-92195 Meudon (France)

2015-11-10

We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ∼ δn/n). The waves are evident as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5–11 minutes and wavelengths <2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with the THEMIS instrument and was found to be 5–14 G. For the typical prominence density the corresponding fast magnetosonic speed is ∼20 km s{sup −1}, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

A study on the fusion reactor - Numerical analyses of MHD equilibrium and= edge plasma transport in tokamak fusion reactor with divertor configurations

Energy Technology Data Exchange (ETDEWEB)

Hong, Sang Hee; Kang, Kyung Doo; Ryu, Ji Myung; Kim, Deok Kyu; Chung, TaeKyun; Chung, Mo Se [Seoul National University, Seoul (Korea, Republic of); Cho, Su Won [Kyungki University, Suwon (Korea, Republic of)

1995-08-01

In the present project for developing the numerical codes of 2-D MHD equilibrium, edge plasma transport and neutral particle transport for the tokamak plasmas, we computed the MHD equilibria of single and double null configurations and determined the external coil currents and the plasma parameters used for operation and control data. Also we numerically acquired the distributions of edge plasma parameters in poloidal and radial directions= and the design-related values according to the various operating conditions using the developed plasma transport code. Furthermore, a neutral particle transport code for the edge region is developed and them used for the analysis of the neutral particle behavior yielding the source terms in the fluid transport equations, and expected to supply the input parameters for the edge plasma transport code. 53 refs., 12 tabs., 44 figs. (author)

Synoptic, Global Mhd Model For The Solar Corona

Science.gov (United States)

Cohen, Ofer; Sokolov, I. V.; Roussev, I. I.; Gombosi, T. I.

2007-05-01

The common techniques for mimic the solar corona heating and the solar wind acceleration in global MHD models are as follow. 1) Additional terms in the momentum and energy equations derived from the WKB approximation for the Alfv’en wave turbulence; 2) some empirical heat source in the energy equation; 3) a non-uniform distribution of the polytropic index, γ, used in the energy equation. In our model, we choose the latter approach. However, in order to get a more realistic distribution of γ, we use the empirical Wang-Sheeley-Arge (WSA) model to constrain the MHD solution. The WSA model provides the distribution of the asymptotic solar wind speed from the potential field approximation; therefore it also provides the distribution of the kinetic energy. Assuming that far from the Sun the total energy is dominated by the energy of the bulk motion and assuming the conservation of the Bernoulli integral, we can trace the total energy along a magnetic field line to the solar surface. On the surface the gravity is known and the kinetic energy is negligible. Therefore, we can get the surface distribution of γ as a function of the final speed originating from this point. By interpolation γ to spherically uniform value on the source surface, we use this spatial distribution of γ in the energy equation to obtain a self-consistent, steady state MHD solution for the solar corona. We present the model result for different Carrington Rotations.

3D MHD simulations of pellet injection and disruptions in tokamak plasmas

International Nuclear Information System (INIS)

Strauss, H.R.; Park, W.; Belova, E.; Fu, G.Y.; Sugiyama, L.E.

2001-01-01

Nonlinear MHD simulation results of pellet injection show that MHD forces can accelerate large pellets, injected on the high field side of a tokamak, to the plasma center. Magnetic reconnection can produce a reverse shear q profile. Ballooning instability caused by pellets is also reduced by high field side injection. Studies are also reported of the current quench phase of disruptions, which can cause 3D halo currents and runaway electrons. (author)

3D MHD simulations of pellet injection and disruptions in tokamak plasmas

International Nuclear Information System (INIS)

Strauss, H.R.; Park, W.; Belova, E.; Fu, G.Y.; Sugiyama, L.E.

1999-01-01

Nonlinear MHD simulation results of pellet injection show that MHD forces can accelerate large pellets, injected on the high field side of a tokamak, to the plasma center. Magnetic reconnection can produce a reverse shear q profile. Ballooning instability caused by pellets is also reduced by high field side injection. Studies are also reported of the current quench phase of disruptions, which can cause 3D halo currents and runaway electrons. (author)

Office of Fusion Energy computational review

International Nuclear Information System (INIS)

Cohen, B.I.; Cohen, R.H.; Byers, J.A.

1996-01-01

The LLNL MFE Theory and Computations Program supports computational efforts in the following areas: (1) Magnetohydrodynamic equilibrium and stability; (2) Fluid and kinetic edge plasma simulation and modeling; (3) Kinetic and fluid core turbulent transport simulation; (4) Comprehensive tokamak modeling (CORSICA Project) - transport, MHD equilibrium and stability, edge physics, heating, turbulent transport, etc. and (5) Other: ECRH ray tracing, reflectometry, plasma processing. This report discusses algorithm and codes pertaining to these areas

Heat transfer including radiation and slag particles evolution in MHD channel-I

International Nuclear Information System (INIS)

Im, K.H.; Ahluwalia, R.K.

1980-01-01

Accurate estimates of convective and radiative heat transfer in the magnetohydrodynamic channel are provided. Calculations performed for a base load-size channel indicate that heat transfer by gas radiation almost equals that by convection for smooth walls, and amounts to 70% as much as the convective heat transfer for rough walls. Carbon dioxide, water vapor, and potassium atoms are the principal participating gases. The evolution of slag particles by homogeneous nucleation and condensation is also investigated. The particle-size spectrum so computed is later utilized to analyze the radiation enhancement by slag particles in the MHD diffuser. The impact of the slag particle spectrum on the selection of a workable and design of an efficient seed collection system is discussed

Review of central power magnetohydrodynamics at the University of Tennessee Space Institute and its relation to the world effort in MHD

International Nuclear Information System (INIS)

Dicks, J.B.

1975-01-01

The first generation of electrical plants powered by MHD generators performs at 50 to 55 percent thermal efficiencies, while later versions of these plants perform at efficiencies up to 75 percent. There are three types of MHD energy conversion: (1) the open-cycle system utilizes the fossil fuel as its heat source, the resulting combustion gas being the working fluid; (2) the closed-cycle generator usually refers to the closed-cycle plasma generator which requires an external heating source to heat a noble gas as the working fluid; and (3) there is the liquid-metal generator which is also closed-cycle, but utilizes a two-phase mixture. The open-cycle system is the most promising, the most advanced, and is emphasized in this paper; the Univ. of Tennessee Space Institute has focused its attention on directly coal-fired MHD generators and has succeeded in demonstrating successful operation. A review of MHD research in the USSR indicates that all three types of generators are being tested, but emphasis is also placed there on the open-cycle system. Its most important facility is the U-25 at the Institute of High Temperatures; this generator was expected to be delivering 20 MW by the end of 1975. The cost savings to the U. S. through the development of MHD power generation is discussed. It is concluded that from its development, the sulfur dioxide pollution in high-sulfur coals is reduced by 120 times, nitrogen oxides by many times, particulate matter by 10 times and finally, thermal pollution is reduced by more than 50 percent even without the use of cooling towers. The cost of this development is placed at $410 million in 10 years

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

International Nuclear Information System (INIS)

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

1994-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1976-03-01

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

MHD natural convection in open inclined square cavity with a heated circular cylinder

Science.gov (United States)

Hosain, Sheikh Anwar; Alim, M. A.; Saha, Satrajit Kumar

2017-06-01

MHD natural convection in open cavity becomes very important in many scientific and engineering problems, because of it's application in the design of electronic devices, solar thermal receivers, uncovered flat plate solar collectors having rows of vertical strips, geothermal reservoirs, etc. Several experiments and numerical investigations have been presented for describing the phenomenon of natural convection in open cavity for two decades. MHD natural convection and fluid flow in a two-dimensional open inclined square cavity with a heated circular cylinder was considered. The opposite wall to the opening side of the cavity was first kept to constant heat flux q, at the same time the surrounding fluid interacting with the aperture was maintained to an ambient temperature T∞. The top and bottom wall was kept to low and high temperature respectively. The fluid with different Prandtl numbers. The properties of the fluid are assumed to be constant. As a result a buoyancy force is created inside the cavity due to temperature difference and natural convection is formed inside the cavity. The Computational Fluid Dynamics (CFD) code are used to discretize the solution domain and represent the numerical result to graphical form.. Triangular meshes are used to obtain the solution of the problem. The streamlines and isotherms are produced, heat transfer parameter Nu are obtained. The results are presented in graphical as well as tabular form. The results show that heat flux decreases for increasing inclination of the cavity and the heat flux is a increasing function of Prandtl number Pr and decreasing function of Hartmann number Ha. It is observed that fluid moves counterclockwise around the cylinder in the cavity. Various recirculations are formed around the cylinder. The almost all isotherm lines are concentrated at the right lower corner of the cavity. The object of this work is to develop a Mathematical model regarding the effect of MHD natural convection flow around

Sawtooth oscillations as MHD relaxation process in a plasma

International Nuclear Information System (INIS)

Yoshida, Zensho; Inoue, Nobuyuki; Ogawa, Yuichi

1992-01-01

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

MHD instability studies in ISX-B

International Nuclear Information System (INIS)

Pare, V.K.; Dunlap, J.L.; Navarro, A.P.; Burris, R.D.

1979-01-01

MHD instabilities in Ohmically and beam heated ISX-B plasmas have been studied using collimated x-ray and Mirnov loop diagnostics. The diagnostic systems will be described and the instability signals will be illustrated for a variety of discharges. The latter will include those observed in connection with low and high β operation, density clamping, pellet injection, and deliberate introduction of toroidal field ripple

Influence of wall couple stress in MHD flow of a micropolar fluid in a porous medium with energy and concentration transfer

Science.gov (United States)

Khalid, Asma; Khan, Ilyas; Khan, Arshad; Shafie, Sharidan

2018-06-01

The intention here is to investigate the effects of wall couple stress with energy and concentration transfer in magnetohydrodynamic (MHD) flow of a micropolar fluid embedded in a porous medium. The mathematical model contains the set of linear conservation forms of partial differential equations. Laplace transforms and convolution technique are used for computation of exact solutions of velocity, microrotations, temperature and concentration equations. Numerical values of skin friction, couple wall stress, Nusselt and Sherwood numbers are also computed. Characteristics for the significant variables on the physical quantities are graphically discussed. Comparison with previously published work in limiting sense shows an excellent agreement.

Study of MHD events initiated by pellet injection into T-10 plasmas

International Nuclear Information System (INIS)

Kuteev, B.; Khimchenko, L.; Krylov, S.; Pavlov, Y.; Pustovitov, V.; Sarychev, D.; Sergeev, V.; Skokov, V.; Timokhin, V.

2005-01-01

There are several events which might be responsible for ultra fast transport of heat and particles during pellet ablation stage in a tokamak. Those are jumps of transport coefficients, plasma drifts in the pellet vicinity and MHD events with time scale significantly shorter than the pellet ablation time. The role of the latter is still not very well understood due to a lack of studies. This paper is devoted to detailed study of the effects during the pellet ablation phase (∼ one millisecond) with main objective to determine the relation between pellet (material Li, C., KCl, size and velocity) and plasma parameters ( q-value a the pellet position, plasma density and temperature) which initiate microsecond MHD events in plasma. The pellets were injected into both into Ohmic and ECE heated plasmas (up to 3 MW) in the T-10 tokamak at various stages of the plasma discharge, in a wide range from the very beginning up to the post-disruption stage. It is observed that at some conditions a pellet ablates in the plasma without accompanying MHD events. This occurs at the highest plasma densities even if a pellet penetrates through q=1 magnetic surface. The ablation rate corresponds to NGSM in this case. Small scale events may occur near rational magnetic surfaces and the ablation rate fluctuations may be explained by reconnection. Both increase of the longitudinal heat flow due to plasma conventional from higher temperature region and growth of the electric field generation supra-thermal electrons may be responsible for the enhanced ablation. Large scale MHD events envelop a region inside q<3. It is observed that the MHD-cooled area is not poloidally symmetric. Mechanisms of the phenomena observed and their consequences on tokamak operation are discussed. (Author)

Numerical study of the unstable MHD spectrum of a small aspect ratio, flat current, non-circular tokamak

International Nuclear Information System (INIS)

Berger, D.; Bernard, L.C.; Gruber, R.; Troyon, F.

1980-01-01

The Lausanne ideal MHD stability code ERATO is used to investigate spectral properties of Solovev's equilibrium at small aspect ratios. Two different elongations are considered. Both free and rigid boundary models are computed and compared. Modes characterized by a large radial extension have been found which appear to be due to coupling of m=1 and m=2 modes due to toricity. The internal modes spectrum is compared with the predictions of the full Mercier criterion, taking into account its spatial dependence, and with the ballooning modes stability criterion. (Auth.)

On performance of Krylov smoothing for fully-coupled AMG preconditioners for VMS resistive MHD

Energy Technology Data Exchange (ETDEWEB)

Lin, Paul T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shadid, John N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States). Department of Mathematics and Statistics,; Tsuji, Paul H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-11-01

Here, this study explores the performance and scaling of a GMRES Krylov method employed as a smoother for an algebraic multigrid (AMG) preconditioned Newton- Krylov solution approach applied to a fully-implicit variational multiscale (VMS) nite element (FE) resistive magnetohydrodynamics (MHD) formulation. In this context a Newton iteration is used for the nonlinear system and a Krylov (GMRES) method is employed for the linear subsystems. The efficiency of this approach is critically dependent on the scalability and performance of the AMG preconditioner for the linear solutions and the performance of the smoothers play a critical role. Krylov smoothers are considered in an attempt to reduce the time and memory requirements of existing robust smoothers based on additive Schwarz domain decomposition (DD) with incomplete LU factorization solves on each subdomain. Three time dependent resistive MHD test cases are considered to evaluate the method. The results demonstrate that the GMRES smoother can be faster due to a decrease in the preconditioner setup time and a reduction in outer GMRESR solver iterations, and requires less memory (typically 35% less memory for global GMRES smoother) than the DD ILU smoother.

Report on studies on closed cycle MHD power generation; Closed cycle MHD hatsuden kento hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1991-04-01

Summarized herein are results of the studies on closed cycle MHD (CCMHD) power generation by the study committee. The studied system is based on the MHD gas turbine combined Brayton cycle of about 500,000 kW in output power, firing natural gas as the fuel, and the conceptual design works therefor are completed. The major findings are: the overall plant efficiency: 54.2% at the power transmission side, plot area required per unit power output: 0.04 m{sup 2}/KW, unit construction cost: 251,000 yen/KW, and unit power generation cost: 10.2 yen/KWh. This system will be more operable than the gas turbine combined cycle with steam system, because start-up time, output change rate, optimum load and so on are constrained not on the power generator side but on the gas turbine side. The expected environmental effects include the exhaust gas NOX concentration being equivalent with that associated with the conventional power generator of 2-stage combustion system, quantity of combustion gases to be treated being approximately 40% of that associated with the gas turbine combined cycle, and reduced CO2 gas emissions, resulting from enhanced power generation efficiency. It is expected that the CCMHD system can exhibit higher efficiency than the high-temperature gas turbine combined cycle system. (NEDO)

Studies of MHD generator performance with oxygen enriched coal combustion

Science.gov (United States)

Wormhoudt, J.; Yousefian, V.; Kolb, C. E.; Martinez-Sanchez, M.

1980-07-01

This paper presents calculations made using the Aerodyne PACKAGE (Plasma Analysis, Chemical Kinetics, and Generator Efficiency) computer code which bear on two questions which arise in connection with choices between oxygen enrichment and air preheating to attain the high combustion temperatures needed for open-cycle, coal-fired MHD power generation. The first question is which method produces the highest enthalpy extraction per unit channel length. The second is, in test facilities intended to study tradeoffs between oxygen enrichment and preheated air, can good generator performance be obtained from the same physical channel for different combustor compositions. The answer to the first question is found to depend on what combustor conditions are taken to be comparable. As for the second question, it is found that operation with channel input from off-design combustor conditions can cause serious problems, which can be partially alleviated by changing the channel load factors.

MHD stability limits in the TCV Tokamak

International Nuclear Information System (INIS)

Reimerdes, H.

2001-07-01

Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak a Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field, which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuations. A spatially dense set of magnetic probes, installed inside the TCV vacuum vessel, allows for a fast observation of these fluctuations. The structure and temporal evolution of coherent modes is extracted using several numerical methods. In addition to the setup of the magnetic diagnostic and the implementation of analysis methods, the subject matter of this thesis focuses on four instabilities, which impose local and global stability limits. All of these instabilities are relevant for the operation of a fusion reactor and a profound understanding of their behaviour is required in order to optimise the performance of such a reactor. Sawteeth, which are central relaxation oscillations common to most standard tokamak scenarios, have a significant effect on central plasma parameters. In TCV, systematic scans of the plasma shape have revealed a strong dependence of their behaviour on elongation κ and triangularity δ, with high κ, and low δ leading to shorter sawteeth with smaller crashes. This shape dependence is increased by applying central electron cyclotron heating. The response to additional heating power is determined by the role of ideal or resistive MHD in triggering the sawtooth crash. For plasma shapes where additional heating and consequently, a faster increase of the central pressure shortens the sawteeth, the low experimental limit of the pressure gradient within the q = 1 surface is consistent with ideal MHD predictions. The observed decrease

Design of an Open-Cycle, Vortex MHD Generator

Energy Technology Data Exchange (ETDEWEB)

Thalimer, J. R.; Kurtzrock, R. C.; Simons, W. H.; Bienstock, D. [Pittsburgh Coal Research Center, US Bureau Of Mines, Pittsburgh, PA (United States); Hughes, W. F. [Carnegie-Mellon University, Pittsburgh, PA (United States)

1968-11-15

The US Bureau of Mines has built a vortex MHD generator which combines the combustor-nozzle-duct combination into one integral unit. The vortex MHD generator consists of a cyclone burner, 7.5 in. diameter, 21 in. in length, with the inner wall used as one electrode together with a coaxial centre electrode. Power is obtained by impressing an axial field of 3000 G from an air solenoid magnet. Electrical output is expected to be one kilowatt. For the initial runs natural gas will be burned in oxygen-enriched, preheated air with a subsequent change to coal as a fuel. A theoretical analysis has been completed which predicts the velocity profiles and the electrical output characteristics of the generator. This analysis assumes variations in the radial and axial directions for all variables, steady state inviscid flow, constant electrical conductivity and a small magnetic Reynolds number. (author)

Studies on the crossed flow type MHD turbines

International Nuclear Information System (INIS)

Hori, Toshihiro; Katsurai, Makoto

1981-01-01

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

Summary report for ITER task - T68: MHD facility preparation for Li/V blanket option

International Nuclear Information System (INIS)

Reed, C.B.; Haglund, R.C.; Miller, M.E.

1995-08-01

A key feasibility issue for the ITER Vanadium/Lithium breeding blanket is the question of insulator coatings. Design calculations show that an electrically insulating layer is necessary to maintain an acceptably low MHD pressure drop. To enable experimental investigations of the MHD performance of candidate insulator materials and the technology for putting them in place, the room-temperature ALEX (Argonne's Liquid Metal EXperiment) NaK facility was upgraded to a 300 degrees C lithium system. The objective of this upgrade was to modify the existing facility to the minimum extent necessary, consistent with providing a safe, flexible, and easy to operate MHD test facility which uses lithium at ITER-relevant temperatures, Hartmann numbers, and interaction parameters. The facility was designed to produce MHD pressure drop data, test section voltage distributions, and heat transfer data for mid-scale test sections and blanket mockups. The system design description for this lithium upgrade of the ALEX facility is given in this document

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

Science.gov (United States)

Alipour, Ramin; Ghanbari, Mohamad R.

2018-04-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-15

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

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

International Nuclear Information System (INIS)

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

2004-01-01

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

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

International Nuclear Information System (INIS)

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

1985-10-01

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

An MHD Simulation of Solar Active Region 11158 Driven with a Time-dependent Electric Field Determined from HMI Vector Magnetic Field Measurement Data

Science.gov (United States)

Hayashi, Keiji; Feng, Xueshang; Xiong, Ming; Jiang, Chaowei

2018-03-01

For realistic magnetohydrodynamics (MHD) simulation of the solar active region (AR), two types of capabilities are required. The first is the capability to calculate the bottom-boundary electric field vector, with which the observed magnetic field can be reconstructed through the induction equation. The second is a proper boundary treatment to limit the size of the sub-Alfvénic simulation region. We developed (1) a practical inversion method to yield the solar-surface electric field vector from the temporal evolution of the three components of magnetic field data maps, and (2) a characteristic-based free boundary treatment for the top and side sub-Alfvénic boundary surfaces. We simulate the temporal evolution of AR 11158 over 16 hr for testing, using Solar Dynamics Observatory/Helioseismic Magnetic Imager vector magnetic field observation data and our time-dependent three-dimensional MHD simulation with these two features. Despite several assumptions in calculating the electric field and compromises for mitigating computational difficulties at the very low beta regime, several features of the AR were reasonably retrieved, such as twisting field structures, energy accumulation comparable to an X-class flare, and sudden changes at the time of the X-flare. The present MHD model can be a first step toward more realistic modeling of AR in the future.

Quantum chaos theory and the spectrum of ideal-MHD instabilities in toroidal plasmas

International Nuclear Information System (INIS)

Dewar, Robert L.; Carolin, Nuehrenberg; Tatsuno, Tomoya

2004-01-01

In a fully 3-D system such as a stellarator, the toroidal mode number n ceases to be a good quantum number - all ns within a given mode family being coupled. It is found that the discrete spectrum of unstable ideal MHD (magnetohydrodynamic) instabilities ceases to exist unless MHD is modified (regularized) by introducing a short-perpendicular-wavelength cutoff. Attempts to use ray tracing to estimate the regularized MHD spectrum fail due to the occurrence of chaotic ray trajectories. In quantum chaos theory, strong chaos in the semiclassical limit leads to eigenvalue statistics the same as those of a suitable ensemble of random matrices. For instance, the probability distribution function for the separation between neighboring eigenvalues is as derived from random matrix theory and goes to zero at zero separation. This contrasts with the Poissonian distribution found in separable systems, showing that a signature of quantum chaos is level repulsion. In order to determine whether eigenvalues of the regularized MHD problem obey the same statistics as those of the Schroedinger equation in both the separable 1-D case and the chaotic 3-D cases, we have assembled data sets of ideal MHD eigenvalues for a Suydam-unstable cylindrical (1-D) equilibrium using Mathematica and a Mercier-unstable (3-D) equilibrium using the CAS3D code. In the 1-D case, we find that the unregularized Suydam-approximation spectrum has an anomalous peak at zero eigenvalue separation. On the other hand, regularization by restricting the domain of κsub(perpendicular) recovers the expected Poissonian distribution. In the 3-D case we find strong evidence of level repulsion within mode families, but mixing mode families produces Poissonian statistics. (author)

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

Science.gov (United States)

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.

MHD stability of vertically asymmetric tokamak equilibria

International Nuclear Information System (INIS)

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

1981-03-01

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

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

Science.gov (United States)

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

2001-01-01

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

Conceptual design study of potential early commercial MHD powerplant. Report of task 2 results

Science.gov (United States)

Hals, F. A.

1981-03-01

The conceptual design of one of the potential early commercial MHD power plants was studied. The plant employs oxygen enrichment of the combustion air and preheating of this oxygen enriched air to an intermediate temperature of 1200 F attainable with a tubular type recuperative heat exchanger. Conceptual designs of plant componets and equipment with performance, operational characteristics, and costs are reported. Plant economics and overall performance including full and part load operation are reviewed. The projected performance and estimated cost of this early MHD plant are compared to conventional power plants, although it does not offer the same high efficiency and low costs as the mature MHD power plant. Environmental aspects and the methods incorporated in plant design for emission control of sulfur and nitrogen are reviewed.

Doubly stratified MHD tangent hyperbolic nanofluid flow due to permeable stretched cylinder

Science.gov (United States)

Nagendramma, V.; Leelarathnam, A.; Raju, C. S. K.; Shehzad, S. A.; Hussain, T.

2018-06-01

An investigation is exhibited to analyze the presence of heat source and sink in doubly stratified MHD incompressible tangent hyperbolic fluid due to stretching of cylinder embedded in porous space under nanoparticles. To develop the mathematical model of tangent hyperbolic nanofluid, movement of Brownian and thermophoretic are accounted. The established equations of continuity, momentum, thermal and solutal boundary layers are reassembled into sets of non-linear expressions. These assembled expressions are executed with the help of Runge-Kutta scheme with MATLAB. The impacts of sundry parameters are illustrated graphically and the engineering interest physical quantities like skin friction, Nusselt and Sherwood number are examined by computing numerical values. It is clear that the power-law index parameter and curvature parameter shows favorable effect on momentum boundary layer thickness whereas Weissennberg number reveals inimical influence.

Laboratory Plasma Source as an MHD Model for Astrophysical Jets

Science.gov (United States)

Mayo, Robert M.

1997-01-01

The significance of the work described herein lies in the demonstration of Magnetized Coaxial Plasma Gun (MCG) devices like CPS-1 to produce energetic laboratory magneto-flows with embedded magnetic fields that can be used as a simulation tool to study flow interaction dynamic of jet flows, to demonstrate the magnetic acceleration and collimation of flows with primarily toroidal fields, and study cross field transport in turbulent accreting flows. Since plasma produced in MCG devices have magnetic topology and MHD flow regime similarity to stellar and extragalactic jets, we expect that careful investigation of these flows in the laboratory will reveal fundamental physical mechanisms influencing astrophysical flows. Discussion in the next section (sec.2) focuses on recent results describing collimation, leading flow surface interaction layers, and turbulent accretion. The primary objectives for a new three year effort would involve the development and deployment of novel electrostatic, magnetic, and visible plasma diagnostic techniques to measure plasma and flow parameters of the CPS-1 device in the flow chamber downstream of the plasma source to study, (1) mass ejection, morphology, and collimation and stability of energetic outflows, (2) the effects of external magnetization on collimation and stability, (3) the interaction of such flows with background neutral gas, the generation of visible emission in such interaction, and effect of neutral clouds on jet flow dynamics, and (4) the cross magnetic field transport of turbulent accreting flows. The applicability of existing laboratory plasma facilities to the study of stellar and extragalactic plasma should be exploited to elucidate underlying physical mechanisms that cannot be ascertained though astrophysical observation, and provide baseline to a wide variety of proposed models, MHD and otherwise. The work proposed herin represents a continued effort on a novel approach in relating laboratory experiments to

Observation of voltage fluctuations in a superconducting magnet during MHD power generation

International Nuclear Information System (INIS)

Smith, R.P.; Niemann, R.C.; Kraimer, M.R.; Zinneman, T.E.

1978-01-01

Fluctuating voltage signals on the potential taps of the ANL 5.0 T MHD Superconducting Dipole Magnet have been observed during MHD power generation at the U-25B Facility at the High Temperature Institute (IVTAN) Moscow, USSR. Various other thermodynamic and electrical parameters of the U-25B flow train have been recorded, and statistical analysis concerning correlations between the phenomena with a view of discerning causal interdependence is in progress. Voltage fluctuations observed at the magnet terminals are analyzed with special emphasis on magnet stability

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

International Nuclear Information System (INIS)

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

2007-01-01

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

A hybrid LLR-MHD model of kink perturbations in EXTRAP

International Nuclear Information System (INIS)

Lehnert, B.

1987-07-01

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

Direct numerical simulation of MHD flow with electrically conducting wall

International Nuclear Information System (INIS)

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

2006-01-01

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

A high current density DC magnetohydrodynamic (MHD) micropump

NARCIS (Netherlands)

Homsy, Alexandra; Koster, Sander; Hogen-Koster, S.; Eijkel, Jan C.T.; van den Berg, Albert; Lucklum, F.; Verpoorte, E.; de Rooij, Nico F.

2005-01-01

This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-µm-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachined

A high current density DC magnetohydrodynamic (MHD) micropump

NARCIS (Netherlands)

Homsy, A; Koster, Sander; Eijkel, JCT; van den Berg, A; Lucklum, F; Verpoorte, E; de Rooij, NF

2005-01-01

This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-mu m-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a

Boundary modulation effects on MHD instabilities in Heliotrons

International Nuclear Information System (INIS)

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

2005-01-01

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

An new MHD/kinetic model for exploring energetic particle production in macro-scale systems

Science.gov (United States)

Drake, J. F.; Swisdak, M.; Dahlin, J. T.

2017-12-01

A novel MHD/kinetic model is being developed to explore magneticreconnection and particle energization in macro-scale systems such asthe solar corona and the outer heliosphere. The model blends the MHDdescription with a macro-particle description. The rationale for thismodel is based on the recent discovery that energetic particleproduction during magnetic reconnection is controlled by Fermireflection and Betatron acceleration and not parallel electricfields. Since the former mechanisms are not dependent on kineticscales such as the Debye length and the electron and ion inertialscales, a model that sheds these scales is sufficient for describingparticle acceleration in macro-systems. Our MHD/kinetic model includesmacroparticles laid out on an MHD grid that are evolved with the MHDfields. Crucially, the feedback of the energetic component on the MHDfluid is included in the dynamics. Thus, energy of the total system,the MHD fluid plus the energetic component, is conserved. The systemhas no kinetic scales and therefore can be implemented to modelenergetic particle production in macro-systems with none of theconstraints associated with a PIC model. Tests of the new model insimple geometries will be presented and potential applications will bediscussed.

A Fast MHD Code for Gravitationally Stratified Media using ...

Indian Academy of Sciences (India)

namic (MHD) algorithms are important for numerical modelling of highly .... include OpenMP-style pragma-based programming, e.g., developed by PGI, HMPP, .... Thus, the formula (10) returns the one-dimensional index for a field point. A.

Design of MHD generator systems

International Nuclear Information System (INIS)

Buende, R.; Raeder, J.

1975-01-01

By assessment of the influence of the combustion efficiency on the electric output of the MHD generator, it can be shown that the construction and efficiency of the generator strongly depend on these parameters. The solutions of this system of equations are discussed. Following a derivation of criteria and boundary conditions of the design and a determination of the specific construction costs of individual system components, it is shown how the single design parameters influence the operational characteristics of such a system, especially the output, efficiency and energy production costs. (GG/LH) [de

Preliminary project definition for long duration. Tests of coal fired MHD generators

International Nuclear Information System (INIS)

Van der Laken, R.A.

1992-01-01

In its final report the Faraday Working Group recommended the CEC amongst others to explore the possibility of a long duration test of a 'state-of-the-art', MHD-generator in order to remove uncertainties concerning the lifetime and availability of such a generator design. The duration of the test should be several thousands of hours, considerably more than the duration tests carried out until now. The scope of the present study is to prepare a project definition document for a long duration test of a coal fired, state-of-the-art MHD-generator

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

International Nuclear Information System (INIS)

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

2004-01-01

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

MHD induced fast-ion losses on ASDEX Upgrade

International Nuclear Information System (INIS)

GarcIa-Munoz, M.; Fahrbach, H.-U.; Bobkov, V.; Bruedgam, M.; Guenter, S.; Igochine, V.; Lauber, Ph.; Mantsinen, M.J.; Maraschek, M.; Poli, E.; Sassenberg, K.; Tardini, G.; Zohm, H.; Pinches, S.D.; Gobbin, M.; Marrelli, L.; Martin, P.; Piovesan, P.

2009-01-01

A detailed knowledge of the interplay between MHD instabilities and energetic particles has been gained from direct measurements of fast-ion losses (FILs). Time-resolved energy and pitch angle measurements of FIL caused by neoclassical tearing modes (NTMs) and toroidicity-induced Alfven eigenmodes (TAEs) have been obtained using a scintillator based FIL detector. The study of FIL due to TAEs has revealed the existence of a new core-localized MHD fluctuation, the Sierpes mode. The Sierpes mode is a non-pure Alfvenic fluctuation which appears in the acoustic branch, dominating the transport of fast-ions in ICRF heated discharges. The internal structure of both TAEs and Sierpes mode has been reconstructed by means of highly resolved multichord soft x-ray measurements. A spatial overlapping of their eigenfunctions leads to a FIL coupling, showing the strong influence that a core-localized fast-ion driven MHD instability may have on the fast-ion transport. We have identified the FIL mechanisms due to NTMs as well as due to TAEs. Drift islands formed by fast-ions in particle phase space are responsible for the loss of NBI fast-ions due to NTMs. In ICRF heated plasmas, a resonance condition fulfilled by the characteristic trapped fast-ion orbit frequencies leads to a phase matching between fast-ion orbit and NTM or TAE magnetic fluctuation. The banana tips of a resonant trapped fast-ion bounce radially due to an E x B drift in the TAE case. The NTM radial bounce of the fast-ion banana tips is caused by the radial component of the perturbed magnetic field lines.

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

Science.gov (United States)

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.

Algorithm and exploratory study of the Hall MHD Rayleigh-Taylor instability

International Nuclear Information System (INIS)

Gardiner, Thomas Anthony

2010-01-01

This report is concerned with the influence of the Hall term on the nonlinear evolution of the Rayleigh-Taylor (RT) instability. This begins with a review of the magnetohydrodynamic (MHD) equations including the Hall term and the wave modes which are present in the system on time scales short enough that the plasma can be approximated as being stationary. In this limit one obtains what are known as the electron MHD (EMHD) equations which support two characteristic wave modes known as the whistler and Hall drift modes. Each of these modes is considered in some detail in order to draw attention to their key features. This analysis also serves to provide a background for testing the numerical algorithms used in this work. The numerical methods are briefly described and the EMHD solver is then tested for the evolution of whistler and Hall drift modes. These methods are then applied to study the nonlinear evolution of the MHD RT instability with and without the Hall term for two different configurations. The influence of the Hall term on the mixing and bubble growth rate are analyzed.

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

Science.gov (United States)

Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go

2016-05-10

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

Two dimensional analysis of MHD generator by means of equivalent circuit

International Nuclear Information System (INIS)

Yoshida, Masaharu; Umoto, Juro

1975-01-01

The authors report on the method analyzing generally the MHD generator by means of the equivalent circuit including the negative resistance. At first, they divide the duct space into many space elements, and for each space element they derive the fundamental equivalent four-terminal circuit which satisfies the two-dimensional Ohm's law. Next, they make an attempt to apply the equivalent circuits to the typical MHD generators such as diagonal, Faraday and Hall generators considering the boundary layer in the duct and the wall leakage current. Using their analysis, the current density, Joul's heat, generated and output electrical powers, electrical efficiency etc. in the generator can be fairly easily calculated. (auth.)

Nonlinear MHD dynamics of tokamak plasmas on multiple time scales

International Nuclear Information System (INIS)

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

2003-01-01

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

MHD Hele-Shaw flow of Rivlin-Ericksen fluid

International Nuclear Information System (INIS)

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

1995-01-01

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

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

International Nuclear Information System (INIS)

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

1985-01-01

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

Structure of reconnection boundary layers in incompressible MHD

International Nuclear Information System (INIS)

Sonnerup, B.U.Oe.; Wang, D.J.

1987-01-01

The incompressible MHD equations with nonvanishing viscosity and resistivity are simplified by use of the boundary layer approximation to describe the flow and magnetic field in the exit flow regions of magnetic field reconnection configurations when the reconnection rate is small. The conditions are derived under which self-similar solutions exist of the resulting boundary layer equations. For the case of zero viscosity and resistivity, the equations describing such self-similar layers are then solved in terms of quadratures, and the resulting flow and field configurations are described. Symmetric solutions, relevant, for example, to reconnection in the geomagnetic tail, as well as asymmetric solutions, relevant to reconnection at the earth's magnetopause, are found to exist. The nature of the external solutions to which the boundary layer solutions should be matched is discussed briefly, but the actual matching, which is to occur at Alfven-wave characteristic curves in the boundary layer solutions, is not carried out. Finally, it is argued that the solutions obtained may also be used to describe the structure of the intense vortex layers observed to occur at magnetic separatrices in computer simulations and in certain analytical models of the reconnection process

Computing the damping and destabilization of global Alfven waves in tokamaks

International Nuclear Information System (INIS)

Kerner, W.; Keegan, B.; Goedbloed, J.P.; Huysmans, G.T.A.

1991-01-01

The role of ideal MHD in magnetic fusion is in the first place to discover magnetic geometries with favourable equilibrium and stability properties. Non-ideal effects cause slower and weaker instabilities leading to enhanced transport and often to violent disruptions. MHD spectroscopy, i.e. the identification of ideal and dissipative MHD modes for the purpose of diagnosing tokamaks and optimising their stability properties, requires a numerical tool which accurately calculates the dissipative MHD spectra for measured equilibria. The new spectral code CASTOR (Complex Alfven Spectrum for TORoidal Plasmas), together with the equilibrium solver HELENA, provides such a tool. In CASTOR, the fluid variables ρ, v, T, and b are discretized by means of a combination of cubic Hermite and quadratic finite elements for the radial direction and Fourier modes for the poloidal coordinate. The equilibrium in non-orthogonal flux coordinates ψ, θ, φ with straight field lines is computed using isoparametric bicubic Hermite elements, resulting in a very accurate representation of the metric elements. Finally, for analysis of JET discharges the equilibrium solver HELENA is interfaced with the equilibrium identification code IDENTC(D). (author) 5 refs., 5 figs

Status report on the Indian MHD programme

International Nuclear Information System (INIS)

Ambasankaran, C.

1978-03-01

MHD programme in India, which has been started recently as a collaborative effort by the Bhabha Atomic Research Centre and Bharat Heavy Electricals Ltd., with the technical consultation provided by the High Temperature Institute, Moscow, is described. The basic considerations which led to the launching of this project and the details of the experimental plant for R and D work are spelt out. (K.B.)

Standing Slow MHD Waves in Radiatively Cooling Coronal Loops ...

Indian Academy of Sciences (India)

The standing slow magneto-acoustic oscillations in cooling coronal loops ... turbation and, eventually, reduces the MHD equations to a 1D system modelling ..... where the function Q is expanded in power series with respect to ǫ, i.e.,. Q = Q0 + ...

Unsteady MHD free convective flow past a vertical porous plate ...

African Journals Online (AJOL)

user

International Journal of Engineering, Science and Technology .... dimensional MHD boundary layer on the body with time varying temperature. ... flow of an electrically conducting fluid past an infinite vertical porous flat plate coinciding with.

MHD simulations on an unstructured mesh

International Nuclear Information System (INIS)

Strauss, H.R.; Park, W.

1996-01-01

We describe work on a full MHD code using an unstructured mesh. MH3D++ is an extension of the PPPL MH3D resistive full MHD code. MH3D++ replaces the structured mesh and finite difference / fourier discretization of MH3D with an unstructured mesh and finite element / fourier discretization. Low level routines which perform differential operations, solution of PDEs such as Poisson's equation, and graphics, are encapsulated in C++ objects to isolate the finite element operations from the higher level code. The high level code is the same, whether it is run in structured or unstructured mesh versions. This allows the unstructured mesh version to be benchmarked against the structured mesh version. As a preliminary example, disruptions in DIIID reverse shear equilibria are studied numerically with the MH3D++ code. Numerical equilibria were first produced starting with an EQDSK file containing equilibrium data of a DIII-D L-mode negative central shear discharge. Using these equilibria, the linearized equations are time advanced to get the toroidal mode number n = 1 linear growth rate and eigenmode, which is resistively unstable. The equilibrium and linear mode are used to initialize 3D nonlinear runs. An example shows poloidal slices of 3D pressure surfaces: initially, on the left, and at an intermediate time, on the right

Recent Progress in MHD Stability Calculations of Compact Stellarators

International Nuclear Information System (INIS)

Fu, G.Y.; Ku, L.P.; Redi, M.H.; Kessel, C.; Monticello, D.A.; Reiman, A.; Cooper, W.A.; Nuehrenberg, C.; Sanchez, R.; Ware, A.; Hirshman, S.P.; Spong, D.A.

2000-01-01

A key issue for compact stellarators is the stability of beta-limiting MHD modes, such as external kink modes driven by bootstrap current and pressure gradient. We report here recent progress in MHD stability studies for low-aspect-ratio Quasi-Axisymmetric Stellarators (QAS) and Quasi-Omnigeneous Stellarators (QOS). We find that the N = 0 periodicity-preserving vertical mode is significantly more stable in stellarators than in tokamaks because of the externally generated rotational transform. It is shown that both low-n external kink modes and high-n ballooning modes can be stabilized at high beta by appropriate 3D shaping without a conducting wall. The stabilization mechanism for external kink modes in QAS appears to be an enhancement of local magnetic shear due to 3D shaping. The stabilization of ballooning mode in QOS is related to a shortening of the normal curvature connection length

Model for ICRF fast wave current drive in self-consistent MHD equilibria

International Nuclear Information System (INIS)

Bonoli, P.T.; Englade, R.C.; Porkolab, M.; Fenstermacher, M.E.

1993-01-01

Recently, a model for fast wave current drive in the ion cyclotron radio frequency (ICRF) range was incorporated into the current drive and MHD equilibrium code ACCOME. The ACCOME model combines a free boundary solution of the Grad Shafranov equation with the calculation of driven currents due to neutral beam injection, lower hybrid (LH) waves, bootstrap effects, and ICRF fast waves. The equilibrium and current drive packages iterate between each other to obtain an MHD equilibrium which is consistent with the profiles of driven current density. The ICRF current drive package combines a toroidal full-wave code (FISIC) with a parameterization of the current drive efficiency obtained from an adjoint solution of the Fokker Planck equation. The electron absorption calculation in the full-wave code properly accounts for the combined effects of electron Landau damping (ELD) and transit time magnetic pumping (TTMP), assuming a Maxwellian (or bi-Maxwellian) electron distribution function. Furthermore, the current drive efficiency includes the effects of particle trapping, momentum conserving corrections to the background Fokker Planck collision operator, and toroidally induced variations in the parallel wavenumbers of the injected ICRF waves. This model has been used to carry out detailed studies of advanced physics scenarios in the proposed Tokamak Physics Experiment (TPX). Results are shown, for example, which demonstrate the possibility of achieving stable equilibria at high beta and high bootstrap current fraction in TPX. Model results are also shown for the proposed ITER device

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

Energy Technology Data Exchange (ETDEWEB)

NONE

1983-03-01

'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1982 reported. This year is the final year of this research; therefore, reexamination was made from the practical standpoint on the R and D of coal fired MHD generation, evaluating the present technological level as well as clarifying the development procedures, with proposals made as to the R and D from now on. The present technological level in the practicability is still in the basic stage, where the essential problem is the development of combustors, air heaters and generation channels in particular. An examination was conducted for the problems, procedures and period of the development for each component equipment, with the results provided as materials for studying the path to the experimental plant of 100 MW heat input. In the method of proceeding with the R and D in the future, it was decided as essential, in order to enter the stage of the experimental plant from the element technology development, that R and D is carried out on the unestablished component technology, making sure that no excessive risk is taken in scaling up to the next stage. (NEDO)

MHD convective flow of magnetite-Fe3O4 nanoparticles by curved stretching sheet

Directory of Open Access Journals (Sweden)

Tasawar Hayat

Full Text Available Present work is devoted to convective flow of ferrofluid due to non linear stretching curved sheet. Electrically conducting fluid is considered in the presence of uniform magnetic field. Nanofluid comprises water and magnetite-Fe3O4 as nanoparticles. Thermal radiation and heat generation/absorption are explained. Homotopy concept is utilized for the development of solutions. Highly nonlinear partial differential systems are reduced into the nonlinear ordinary differential system. Impact of non-dimensional radius of curvature and power law index on the physical quantities like fluid pressure, velocity and temperature field are examined. Computations for surface shear stress and heat transfer rate also analyzed. Keywords: MHD nanofluid, Thermal radiation, Porous medium, Convective boundary conditions, Non-linear curved stretching sheet

Convective plasma stability consistent with MHD equilibrium in magnetic confinement systems with a decreasing field

International Nuclear Information System (INIS)

Tsventoukh, M. M.

2010-01-01

A study is made of the convective (interchange, or flute) plasma stability consistent with equilibrium in magnetic confinement systems with a magnetic field decreasing outward and large curvature of magnetic field lines. Algorithms are developed which calculate convective plasma stability from the Kruskal-Oberman kinetic criterion and in which the convective stability is iteratively consistent with MHD equilibrium for a given pressure and a given type of anisotropy in actual magnetic geometry. Vacuum and equilibrium convectively stable configurations in systems with a decreasing, highly curved magnetic field are calculated. It is shown that, in convectively stable equilibrium, the possibility of achieving high plasma pressures in the central region is restricted either by the expansion of the separatrix (when there are large regions of a weak magnetic field) or by the filamentation of the gradient plasma current (when there are small regions of a weak magnetic field, in which case the pressure drops mainly near the separatrix). It is found that, from the standpoint of equilibrium and of the onset of nonpotential ballooning modes, a kinetic description of convective stability yields better plasma confinement parameters in systems with a decreasing, highly curved magnetic field than a simpler MHD model and makes it possible to substantially improve the confinement parameters for a given type of anisotropy. For the Magnetor experimental compact device, the maximum central pressure consistent with equilibrium and stability is calculated to be as high as β ∼ 30%. It is shown that, for the anisotropy of the distribution function that is typical of a background ECR plasma, the limiting pressure gradient is about two times steeper than that for an isotropic plasma. From a practical point of view, the possibility is demonstrated of achieving better confinement parameters of a hot collisionless plasma in systems with a decreasing, highly curved magnetic field than those

Tests and studies of USSR materials at the US coal burning MHD facility UTSI-2

Energy Technology Data Exchange (ETDEWEB)

Telegin, G P; Romanov, A I; Rekov, A I; Spiridonov, E G; Barodina, T I; Vysotsky, D A

1978-10-01

In accordance with the overall program of the US--USSR cooperation in the field of MHD power generation tests of Soviet electrode materials were conducted at the coal burning MHD facility UTSI-2 of the University of Tennessee Space Institute. The main purposes of the tests are evaluation of electrode materials behavior in the channel of the MHD generator operating with combustion products of coal containing ionizing alkali seed, study of thermal and physical stability of materials in the presence of corrosive slag, study of electrophysical characteristics of electrode materials when they are subjected to the passage of current through the plasma-slag-electrode system. Tests were conducted on electrodes made of silicon carbide doped with titanium and LaCrO/sub 3/--Cr cermet. Results are reported on the phase and chemical composition and structure of these two materials, their thermophysical and electrophysical properties, and the electrode fabrication methods. The MHD facility UTSI-2, where the tests were conducted is one of few utilizing actual coal as the fuel. A description of this facility is given, and its main operating parameters and the methods used to conduct electrode tests with and without an applied current are described.

Hopes for commercial use of MHD

International Nuclear Information System (INIS)

1968-01-01

Magnetohydrodynamics (MHD) is the study of the motion of fluids and gases in magnetic fields. After 25 years of theoretical and experimental work, it seems commercially promising for a new type of power station, where heat would be converted directly into electricity by generators without moving parts. Nuclear reactors would be well suited as the heat sources. At an Agency symposium in Warsaw in July it was felt that international cooperation is essential to develop the technique for industrial use. (author)

Characteristics of MHD stability of high beta plasmas in LHD

International Nuclear Information System (INIS)

Sato, M.; Nakajima, N.; Watanabe, K.Y.; Todo, Y.; Suzuki, Y.

2012-11-01

In order to understand characteristics of the MHD stability of high beta plasmas obtained in the LHD experiments, full MHD simulations have been performed for the first time. Since there is a magnetic hill in a plasma peripheral region, the ballooning modes extending into the plasma peripheral region with a chaotic magnetic field are destabilized. However, in the nonlinear phase, the core region comes under the in influence of the instabilities and the central pressure decreases. There is a tendency that modes are suppressed as the beta value and/or magnetic Reynolds number increase, which is consistent with a result that high beta plasmas enter the second stable region of the ideal ballooning modes as beta increases and remaining destabilized ballooning modes are considered to be resistive type. (author)

MHD marking using the MSE polarimeter optics in ILW JET plasmas

CERN Document Server

Reyes Cortes, S.; Alves, D.; Baruzzo, M.; Bernardo, J.; Buratti, P.; Coelho, R.; Challis, C.; Chapman, I.; Hawkes, N.; Hender, T.C.; Hobirk, J.; Joffrin, E.

2016-01-01

In this communication we propose a novel diagnostic technique, which uses the collection optics of the JET Motional Stark Effect (MSE) diagnostic, to perform polarimetry marking of observed MHD in high temperature plasma regimes. To introduce the technique, first we will present measurements of the coherence between MSE polarimeter, electron cyclotron emission, and Mirnov coil signals aiming to show the feasibility of the method. The next step consists of measuring the amplitude fluctuation of the raw MSE polarimeter signals, for each MSE channel, following carefully the MHD frequency on Mirnov coil data spectrograms. A variety of experimental examples in JET ITER-Like Wall (ILW) plasmas are presented, providing an adequate picture and interpretation for the MSE optics polarimeter technique.

Kinetic analysis of MHD ballooning modes in tokamaks

International Nuclear Information System (INIS)

Tang, W.M.; Rewoldt, G.; Cheng, C.Z.; Chance, M.S.

1984-10-01

A comprehensive analysis of the stability properties of the appropriate kinetically generalized form of MHD ballooning modes together with the usual trapped-particle drift modes is presented. The calculations are fully electromagnetic and include the complete dynamics associated with compressional ion acoustic waves. Trapped-particle effects along with all forms of collisionless dissipation are taken into account without approximations. The influence of collisions is estimated with a model Krook operator. Results from the application of this analysis to realistic tokamak operating conditions indicate that unstable short-wavelength modes with significant growth rates can extend from β = 0 to value above the upper ideal-MHD-critical-beta associated with the so-called second stability regime. Since the strength of the relevant modes appears to vary gradually with β, these results support a soft beta limit picture involving a continuous (rather than abrupt or hard) modification of anomalous transport already present in low-β-tokamaks. However, at higher beta the increasing dominance of the electromagnetic component of the perturbations indicated by these calculations could also imply significantly different transport scaling properties

Computation of tokamak equilibria with steady flow

International Nuclear Information System (INIS)

Kerner, W.; Tokuda, Shinji

1987-08-01

The equations for ideal MHD equilibria with stationary flow are reexamined and addressed as numerically applied to tokamak configurations with a free plasma boundary. Both the isothermal (purely toroidal flow) and the poloidal flow cases are treated. Experiment-relevant states with steady flow (so far only in the toroidal direction) are computed by the modified SELENE40 code. (author)

EMAPS: An Efficient Multiscale Approach to Plasma Systems with Non-MHD Scale Effects

Energy Technology Data Exchange (ETDEWEB)

Omelchenko, Yuri A. [Trinum Research, Inc., San Diego, CA (United States)

2016-08-08

Global interactions of energetic ions with magnetoplasmas and neutral gases lie at the core of many space and laboratory plasma phenomena ranging from solar wind entry into and transport within planetary magnetospheres and exospheres to fast-ion driven instabilities in fusion devices to astrophysics-in-lab experiments. The ability of computational models to properly account for physical effects that underlie such interactions, namely ion kinetic, ion cyclotron, Hall, collisional and ionization processes is important for the success and planning of experimental research in plasma physics. Understanding the physics of energetic ions, in particular their nonlinear resonance interactions with Alfvén waves, is central to improving the heating performance of magnetically confined plasmas for future energy generation. Fluid models are not adequate for high-beta plasmas as they cannot fully capture ion kinetic and cyclotron physics (e.g., ion behavior in the presence of magnetic nulls, shock structures, plasma interpenetration, etc.). Recent results from global reconnection simulations show that even in a MHD-like regime there may be significant differences between kinetic and MHD simulations. Therefore, kinetic modeling becomes essential for meeting modern day challenges in plasma physics. The hybrid approximation is an intermediate approximation between the fluid and fully kinetic approximations. It eliminates light waves, removes the electron inertial temporal and spatial scales from the problem and enables full-orbit ion kinetics. As a result, hybrid codes have become effective tools for exploring ion-scale driven phenomena associated with ion beams, shocks, reconnection and turbulence that control the large-scale behavior of laboratory and space magnetoplasmas. A number of numerical issues, however, make three-dimensional (3D) large-scale hybrid simulations of inhomogeneous magnetized plasmas prohibitively expensive or even impossible. To resolve these difficulties

Kinetic-MHD simulations of gyroresonance instability driven by CR pressure anisotropy

Science.gov (United States)

Lebiga, O.; Santos-Lima, R.; Yan, H.

2018-05-01

The transport of cosmic rays (CRs) is crucial for the understanding of almost all high-energy phenomena. Both pre-existing large-scale magnetohydrodynamic (MHD) turbulence and locally generated turbulence through plasma instabilities are important for the CR propagation in astrophysical media. The potential role of the resonant instability triggered by CR pressure anisotropy to regulate the parallel spatial diffusion of low-energy CRs (≲100 GeV) in the interstellar and intracluster medium of galaxies has been shown in previous theoretical works. This work aims to study the gyroresonance instability via direct numerical simulations, in order to access quantitatively the wave-particle scattering rates. For this, we employ a 1D PIC-MHD code to follow the growth and saturation of the gyroresonance instability. We extract from the simulations the pitch-angle diffusion coefficient Dμμ produced by the instability during the linear and saturation phases, and a very good agreement (within a factor of 3) is found with the values predicted by the quasi-linear theory (QLT). Our results support the applicability of the QLT for modelling the scattering of low-energy CRs by the gyroresonance instability in the complex interplay between this instability and the large-scale MHD turbulence.

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

International Nuclear Information System (INIS)

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

1978-01-01

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

Analytical and numerical study of MHD instabilities development in magnetized accretion-ejection structures

International Nuclear Information System (INIS)

Kersale, Evy

2000-01-01

The first part of this work proposes a new version of the mathematical formalism used to describe pressure-driven instabilities in magnetized accretion-ejection structures. Such processes, occurring in magnetically confined plasmas, pose very stringent limits to thermonuclear fusion devices but their influence in astrophysical objects has rarely been considered. In a framework which eliminates fast magnetosonic waves one develops a system of equations allowing us to follow both ballooning and interchange modes. An application of this result to a cylindrical jet being subject to solid rotation shows that the inner parts of such structures are destabilized by magnetic shear. Furthermore, while clarifying somewhat previous studies, one finds that jets confined by a dominant toroidal magnetic field are generically unstable with respect to interchange modes. Moreover, one has written a numerical code to solve the MHD partial differential equations. Starting with a basic algorithm, one has assessed the effects of the geometry, boundary conditions and artificial dissipation on numerical computation. The code has been tested by solving classical hydrodynamic and MHD Riemann problems. A new mechanism of ultra high energy cosmic ray production in gamma-ray bursts composes the last part of this work. In these objects, particles are accelerated up to energies of the order of 10 21 eV, by means of relativistic Alfven perturbations crossings. A stream instability involving a highly relativistic shell of plasma, the fireball, and baryons going through it produces such Alfven fronts. Then, Brillouin-like backscattering processes redistribute the available energy between the forward and backward Alfven waves and the magnetosonic ones. (author) [fr

MHD activity and energy loss during beta saturation and collapse at high beta poloidal in PBX

International Nuclear Information System (INIS)

Kugel, H.W.; Sesnic, S.; Bol, K.

1987-10-01

High-β experiments, in medium to high-q tokamak plasmas, exhibit a temporal β saturation and collapse. This behavior has been attributed to ballooning, ideal kink, or tearing modes. In PBX, a unique diagnostic capability allowed studies of the relation between MHD and energy loss for neutral-beam-heated (<6 MW), mildly indented (10 to 15%), nearly steady I/sub p/ discharges that approached the Troyon-Gruber limit. Under these conditions, correlations between MHD activity and energy losses have shown that the latter can be almost fully accounted for by various long wavelength MHD instabilities and that there is no need to invoke high-n ballooning modes in PBX. 6 refs., 4 figs

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

African Journals Online (AJOL)

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

Comparison of solar photospheric bright points between Sunrise observations and MHD simulations

Science.gov (United States)

Riethmüller, T. L.; Solanki, S. K.; Berdyugina, S. V.; Schüssler, M.; Martínez Pillet, V.; Feller, A.; Gandorfer, A.; Hirzberger, J.

2014-08-01

Bright points (BPs) in the solar photosphere are thought to be the radiative signatures (small-scale brightness enhancements) of magnetic elements described by slender flux tubes or sheets located in the darker intergranular lanes in the solar photosphere. They contribute to the ultraviolet (UV) flux variations over the solar cycle and hence may play a role in influencing the Earth's climate. Here we aim to obtain a better insight into their properties by combining high-resolution UV and spectro-polarimetric observations of BPs by the Sunrise Observatory with 3D compressible radiation magnetohydrodynamical (MHD) simulations. To this end, full spectral line syntheses are performed with the MHD data and a careful degradation is applied to take into account all relevant instrumental effects of the observations. In a first step it is demonstrated that the selected MHD simulations reproduce the measured distributions of intensity at multiple wavelengths, line-of-sight velocity, spectral line width, and polarization degree rather well. The simulated line width also displays the correct mean, but a scatter that is too small. In the second step, the properties of observed BPs are compared with synthetic ones. Again, these are found to match relatively well, except that the observations display a tail of large BPs with strong polarization signals (most likely network elements) not found in the simulations, possibly due to the small size of the simulation box. The higher spatial resolution of the simulations has a significant effect, leading to smaller and more numerous BPs. The observation that most BPs are weakly polarized is explained mainly by the spatial degradation, the stray light contamination, and the temperature sensitivity of the Fe i line at 5250.2 Å. Finally, given that the MHD simulations are highly consistent with the observations, we used the simulations to explore the properties of BPs further. The Stokes V asymmetries increase with the distance to the

Survey of linear MHD stability in tokamak configurations

International Nuclear Information System (INIS)

Wakatani, M.

1977-01-01

The results found by MHD stability studies for both low-beta and high-beta tokamaks are reviewed. The stability against kink-ballooning modes in equilibria surrounded by vacuum or a layer of force free currents is considered. Internal kink modes and the relation to interchange modes, which should be considered after external kink modes are suppressed, are surveyed

Theoretical parameters of powerful radio galaxies. II. Generation of MHD turbulence by collisionless shock waves

International Nuclear Information System (INIS)

Baryshev, Yu.V.; Morozov, V.N.

1988-01-01

It is shown that MHD turbulence can be generated by collisionless shock waves due to anisotropy of the pressure behind the front of the reverse sock at the hot spot of a powerful radio galaxy. The energy density of the MHD turbulence generated behind the shock front is estimated. Analysis of the theoretical studies and experimental data on collisionless shock waves in the solar wind indicates that an important part is played by streams of ions reflected by the shock fronts, the streams generating plasma and MHD turbulence in the region ahead of the front. The extension of these ideas to shock waves in powerful radio galaxies must be made with care because of the great difference between the parameters of the shock waves in the two cases

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

International Nuclear Information System (INIS)

Sudo, Shigeru; Zushi, Hideki; Kondo, Katsumi

1993-01-01

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

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

Directory of Open Access Journals (Sweden)

M. Rajashekar

2012-01-01

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

International Conference on Computational Engineering Science

CERN Document Server

Yagawa, G

1988-01-01

The aim of this Conference was to become a forum for discussion of both academic and industrial research in those areas of computational engineering science and mechanics which involve and enrich the rational application of computers, numerical methods, and mechanics, in modern technology. The papers presented at this Conference cover the following topics: Solid and Structural Mechanics, Constitutive Modelling, Inelastic and Finite Deformation Response, Transient Analysis, Structural Control and Optimization, Fracture Mechanics and Structural Integrity, Computational Fluid Dynamics, Compressible and Incompressible Flow, Aerodynamics, Transport Phenomena, Heat Transfer and Solidification, Electromagnetic Field, Related Soil Mechanics and MHD, Modern Variational Methods, Biomechanics, and Off-Shore-Structural Mechanics.

Thermosolutal MHD flow and radiative heat transfer with viscous ...

African Journals Online (AJOL)

This paper investigates double diffusive convection MHD flow past a vertical porous plate in a chemically active fluid with radiative heat transfer in the presence of viscous work and heat source. The resulting nonlinear dimensionless equations are solved by asymptotic analysis technique giving approximate analytic ...

MHD stability of the ITER pedestal and SOL plasma and its influence on the heat flux width

NARCIS (Netherlands)

Loarte, A.; Liu, F.; Huijsmans, G.T.A.; Kukushkin, A.S.; Pitts, R.A.

2015-01-01

Proceedings of the 21st International Conference on Plasma-Surface Interactions in Controlled Fusion Devices Kanazawa, Japan May 26-30, 2014 MHD stability of ITER plasmas has been analyzed for QDT = 10 edge and SOL plasma conditions, showing that the SOL plasma is MHD stable down to pressure

Using a Virtual Class to Demonstrate Computer-Mediated Group Dynamics Concepts

Science.gov (United States)

Franz, Timothy M.; Vicker, Lauren A.

2010-01-01

We report about an active learning demonstration designed to use a virtual class to present computer-mediated group communication course concepts to show that students can learn about these concepts in a virtual class. We designated 1 class period as a virtual rather than face-to-face class, when class members "attended" virtually using…

Incompressible LFR MHD. A fluid model for stability analysis of a fusion plasma

International Nuclear Information System (INIS)

Scheffel, J.; Faghihi, M.

1986-10-01

A fluid model including FLR effects, named Incompressible Finite Larmor Radius MagnetoHydroDynamics, is presented and derived in this paper. It is an extension of ordinary, incompressible MHD to include the Larmor radius effects due to ion gyroviscosity, Hall current and electron diamagnetism. It is intended to use the model for stability analysis, on the Alfven wave time scale, of a fusion plasma and it is consequently based on transport coefficients in the collisionless limit. It will be demonstrated that for a fairly dense and cool plasma, such as for the EXTRAP z-pinch, all three Larmor radius effects may become important, that for a JET-type plasma no FLR effect is pronounced, and that in a reactor plasma the Hall and electron diamagnetism term may play a role. For scaling lengths signigicantly smaller than the plasma radius the effect of the FLR terms becomes enhanced. To study the importance of the choice of equations of state for the model the m=1 and k 2 r 2 towards infinity instability in cylindrical geometry is given special attention for zero Larmor radius. The full stability criterion of the double adiabatic model, including pressure anisotropy, is presented for what we believe to be the first time. It is found that when perpendicular p > parallel p stability can be reached for very high plasma perpendicular β-values. We demonstrate that no less complicated energy conserving fluid model, which takes into account pressure anisotropy, other than the double adiabativ model can be obtained. Since pressure anisotropy generally only weakly affects stability, we can assume isotropy in the Incompressible FLR MHD model. Also, the energy equation is replaced by the incompressibility condition, making FLR terms appearing in the energy equation irrelevant. (authors)

Active MHD control experiments in RFX-mod

International Nuclear Information System (INIS)

Ortolani, Sergio

2006-01-01

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

MHD simulations of molybdenum X-pinches

International Nuclear Information System (INIS)

Ivanenkov, G.V.; Stepnevski, V.

2002-01-01

One investigates into compression of molybdenum X-pinches applying numerical MHD-models with parabolic and conical initial geometry. The second model describing plasma axial motion in greater detail offers a real geometry of a discharge and is applicable to loads characterized by higher masses in contrast to the first one. Both models enabled to describe all basic phases of compression including origination of a minidiode, occurrence of a narrow neck, microexplosion of a hot point and origination of shock waves followed by sausage instability [ru

Ideal MHD stability and performance of ITER steady-state scenarios with ITBs

Science.gov (United States)

Poli, F. M.; Kessel, C. E.; Chance, M. S.; Jardin, S. C.; Manickam, J.

2012-06-01

Non-inductive steady-state scenarios on ITER will need to operate with internal transport barriers (ITBs) in order to reach adequate fusion gain at typical currents of 9 MA. The large pressure gradients at the location of the internal barrier are conducive to the development of ideal MHD instabilities that may limit the plasma performance and may lead to plasma disruptions. Fully non-inductive scenario simulations with five combinations of heating and current drive sources are presented in this work, with plasma currents in the range 7-10 MA. For each configuration the linear, ideal MHD stability is analysed for variations of the Greenwald fraction and of the pressure peaking factor around the operating point, aiming at defining an operational space for stable, steady-state operations at optimized performance. It is shown that plasmas with lower hybrid heating and current drive maintain the minimum safety factor above 1.5, which is desirable in steady-state operations to avoid neoclassical tearing modes. Operating with moderate ITBs at 2/3 of the minor radius, these plasmas have a minimum safety factor above 2, are ideal MHD stable and reach Q ≳ 5 operating above the ideal no-wall limit.

Heat transfer enhancement of free surface MHD-flow by a protrusion wall

International Nuclear Information System (INIS)

Hulin Huang; Bo Li

2010-01-01

Due to the magnetohydrodynamic (MHD) effect on the flow, which degrades heat transfer coefficients by pulsation suppression of external magnetic field on the flow, a hemispherical protrusion wall is applied to free surface MHD-flow system as a heat transfer enhancement, because the hemispherical protrusion wall has some excellent characteristics including high heat transfer coefficients, low friction factors and high overall thermal performances. So, the characteristics of the fluid flow and heat transfer of the free surface MHD-flow with hemispherical protrusion wall are simulated numerically and the influence of some parameters, such as protrusion height δ/D, and Hartmann number, are also discussed in this paper. It is found that, in the range of Hartmann number 30 ≤ Ha ≤ 70, the protrusion wall assemblies can achieve heat transfer enhancements (Nu/Nu 0 ) of about 1.3-2.3 relative to the smooth channel, while the friction loss (f/f 0 ) increases by about 1.34-1.45. Thus, the high Nusselt number can be obtained when the protrusion wall with a radically lower friction loss increase, which may help get much higher overall thermal performances.

MHD from a Microscopic Concept and Onset of Turbulence in Hartmann Flow

International Nuclear Information System (INIS)

Jirkovsky, L.; Bo-ot, L. Ma.; Chiang, C. M.

2010-01-01

We derive higher order magneto-hydrodynamic (MHD) equations from a microscopic picture using projection and perturbation formalism. In an application to Hartmann flow we find velocity profiles flattening towards the center at the onset of turbulence in hydrodynamic limit. Comparison with the system under the effect of a uniform magnetic field yields difference in the onset of turbulence consistent with observations, showing that the presence of magnetic field inhibits onset of instability or turbulence. The laminar-turbulent transition is demonstrated in a phase transition plot of the development in time of the relative average velocities vs. Reynolds number showing a sharp increase of the relative average velocity at the transition point as determined by the critical Reynolds number. (physics of gases, plasmas, and electric discharges)

Magnus: A New Resistive MHD Code with Heat Flow Terms

Science.gov (United States)

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

2017-07-01

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

Solving free-plasma-boundary problems with the SIESTA MHD code

Science.gov (United States)

Sanchez, R.; Peraza-Rodriguez, H.; Reynolds-Barredo, J. M.; Tribaldos, V.; Geiger, J.; Hirshman, S. P.; Cianciosa, M.

2017-10-01

SIESTA is a recently developed MHD equilibrium code designed to perform fast and accurate calculations of ideal MHD equilibria for 3D magnetic configurations. It is an iterative code that uses the solution obtained by the VMEC code to provide a background coordinate system and an initial guess of the solution. The final solution that SIESTA finds can exhibit magnetic islands and stochastic regions. In its original implementation, SIESTA addressed only fixed-boundary problems. This fixed boundary condition somewhat restricts its possible applications. In this contribution we describe a recent extension of SIESTA that enables it to address free-plasma-boundary situations, opening up the possibility of investigating problems with SIESTA in which the plasma boundary is perturbed either externally or internally. As an illustration, the extended version of SIESTA is applied to a configuration of the W7-X stellarator.

MHD activity triggered by monster sawtooth crashes on Tore Supra

International Nuclear Information System (INIS)

Maget, P; Artaud, J-F; Eriksson, L-G; Huysmans, G; Lazaros, A; Moreau, P; Ottaviani, M; Segui, J-L; Zwingmann, W

2005-01-01

The crash of monster sawteeth in Tore Supra ion cyclotron resonance heated plasmas is observed to trigger long-lived magneto hydrodynamic (MHD) activity, dominated by a (m = 3, n = 2) magnetic perturbation at the edge. This phenomenon is reminiscent of the triggering of neoclassical tearing modes, although in Tore Supra the MHD activity decays and eventually vanishes. It can be explained by the linear destabilization of the (3, 2) mode as the current sheet developed in the non-linear stage of the internal kink relaxation gets closer to q = 3/2. However, the lifetime of the (3, 2) island is longer than the period of linear instability. We find that the neoclassical drive is essential for explaining the observed lifetime and width of the island, although the overall dynamics is controlled by the relaxation of the current profile on a resistive time scale

New insights into MHD dynamics of magnetically confined plasmas from experiments in RFX

International Nuclear Information System (INIS)

Martin, P.; Martini, S.; Antoni, V.

2001-01-01

The experimental and theoretical activity performed in the RFX experiment has allowed a deeper insight into the MHD properties of the RFP configuration. A set of successful experiments has demonstrated the possibility of influencing both the amplitude and the spectrum of the magnetic fluctuations which characterise the RFP configuration. A new regime (QSH states) where the dynamo mechanism works in a nearly laminar way and a helical core plasma is produced has been investigated. With these studies a reduction of the magnetic chaos has been obtained. The continuos rotation of wall locked resistive tearing modes has been obtained by an m=0 rotating perturbation. This perturbation induces rotation of m=1 non-linearly coupled modes. (author)

Hall effects on unsteady MHD reactive flow of second grade fluid through porous medium in a rotating parallel plate channel

Science.gov (United States)

Krishna, M. Veera; Swarnalathamma, B. V.

2017-07-01

We considered the transient MHD flow of a reactive second grade fluid through porous medium between two infinitely long horizontal parallel plates when one of the plate is set into uniform accelerated motion in the presence of a uniform transverse magnetic field under Arrhenius reaction rate. The governing equations are solved by Laplace transform technique. The effects of the pertinent parameters on the velocity, temperature are discussed in detail. The shear stress and Nusselt number at the plates are also obtained analytically and computationally discussed with reference to governing parameters.

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

Mittal, M.L.

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

Flare-induced MHD disturbances in the corona--Moreton waves and type II shocks

International Nuclear Information System (INIS)

Uchida, Y.

1972-01-01

The propagation in the corona of the magnetohydrodynamic (MHD) disturbance possibly emitted at the explosive stage in the initial phase of a flare is considered. The behavior of the MHD fast-mode wavefront, whose source is located at the flare, is calculated by using eiconal-characteristic method in the High Altitude Observatory (HAO) realistic models of coronal magnetic field and density for the days of some particular flare events. It is shown as the result that the peculiar behavior of Moreton' s surface wave and the peculiar appearance in the shape and position of the type II burst sources can be consistently understood by considering the refraction, focussing, and fermation of shocks of MHD fast-mode disturbance in the actual distribution of Alfven velocity in the corona. Based on some comparison of the positions of low-Alfven-velocity regions in the corona with observed positions of type II burst sources, it is proposed that the type II burst sources may be identified with such low-Alfven-velocity regions ''illuminated'' by thus enhanced shocks. (U.S.)

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

Science.gov (United States)

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

1982-01-01

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

The design of a heat transfer liquid metal MHD experiment for ALEX [Argonne Liquid-Metal Experiment

International Nuclear Information System (INIS)

Picologlou, B.F.; Reed, C.B.; Hua, T.Q.; Lavine, A.S.

1988-01-01

An experiment to study heat transfer in liquid metal MHD flow, under conditions relevant to coolant channels for tokamak first wall and high heat flux devices, is described. The experimental configuration is a rectangular duct in a transverse magnetic field, heated on one wall parallel to the field. The specific objective of the experiment is to resolve important issues related to the presence and heat transfer characteristics of wall jets and flow instabilities in MHD flows in rectangular duct with electrically conducting walls. Available analytical tools for MHD thermal hydraulics have been used in the design of the test article and its instrumentation. Proposed tests will cover a wide range of Peclet and Hartmann numbers and interaction parameters. 14 refs., 3 figs., 1 tab

Relativistic modeling capabilities in PERSEUS extended MHD simulation code for HED plasmas

Energy Technology Data Exchange (ETDEWEB)

Hamlin, Nathaniel D., E-mail: nh322@cornell.edu [438 Rhodes Hall, Cornell University, Ithaca, NY, 14853 (United States); Seyler, Charles E., E-mail: ces7@cornell.edu [Cornell University, Ithaca, NY, 14853 (United States)

2014-12-15

We discuss the incorporation of relativistic modeling capabilities into the PERSEUS extended MHD simulation code for high-energy-density (HED) plasmas, and present the latest hybrid X-pinch simulation results. The use of fully relativistic equations enables the model to remain self-consistent in simulations of such relativistic phenomena as X-pinches and laser-plasma interactions. By suitable formulation of the relativistic generalized Ohm’s law as an evolution equation, we have reduced the recovery of primitive variables, a major technical challenge in relativistic codes, to a straightforward algebraic computation. Our code recovers expected results in the non-relativistic limit, and reveals new physics in the modeling of electron beam acceleration following an X-pinch. Through the use of a relaxation scheme, relativistic PERSEUS is able to handle nine orders of magnitude in density variation, making it the first fluid code, to our knowledge, that can simulate relativistic HED plasmas.

Large Scale Earth's Bow Shock with Northern IMF as Simulated by PIC Code in Parallel with MHD Model

Science.gov (United States)

Baraka, Suleiman

2016-06-01

In this paper, we propose a 3D kinetic model (particle-in-cell, PIC) for the description of the large scale Earth's bow shock. The proposed version is stable and does not require huge or extensive computer resources. Because PIC simulations work with scaled plasma and field parameters, we also propose to validate our code by comparing its results with the available MHD simulations under same scaled solar wind (SW) and (IMF) conditions. We report new results from the two models. In both codes the Earth's bow shock position is found to be ≈14.8 R E along the Sun-Earth line, and ≈29 R E on the dusk side. Those findings are consistent with past in situ observations. Both simulations reproduce the theoretical jump conditions at the shock. However, the PIC code density and temperature distributions are inflated and slightly shifted sunward when compared to the MHD results. Kinetic electron motions and reflected ions upstream may cause this sunward shift. Species distributions in the foreshock region are depicted within the transition of the shock (measured ≈2 c/ ω pi for Θ Bn = 90° and M MS = 4.7) and in the downstream. The size of the foot jump in the magnetic field at the shock is measured to be (1.7 c/ ω pi ). In the foreshocked region, the thermal velocity is found equal to 213 km s-1 at 15 R E and is equal to 63 km s -1 at 12 R E (magnetosheath region). Despite the large cell size of the current version of the PIC code, it is powerful to retain macrostructure of planets magnetospheres in very short time, thus it can be used for pedagogical test purposes. It is also likely complementary with MHD to deepen our understanding of the large scale magnetosphere.

MHD stability limits in the TCV Tokamak

Energy Technology Data Exchange (ETDEWEB)

Reimerdes, H. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

2001-07-01

Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak a Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field, which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuations. A spatially dense set of magnetic probes, installed inside the TCV vacuum vessel, allows for a fast observation of these fluctuations. The structure and temporal evolution of coherent modes is extracted using several numerical methods. In addition to the setup of the magnetic diagnostic and the implementation of analysis methods, the subject matter of this thesis focuses on four instabilities, which impose local and global stability limits. All of these instabilities are relevant for the operation of a fusion reactor and a profound understanding of their behaviour is required in order to optimise the performance of such a reactor. Sawteeth, which are central relaxation oscillations common to most standard tokamak scenarios, have a significant effect on central plasma parameters. In TCV, systematic scans of the plasma shape have revealed a strong dependence of their behaviour on elongation {kappa} and triangularity {delta}, with high {kappa}, and low {delta} leading to shorter sawteeth with smaller crashes. This shape dependence is increased by applying central electron cyclotron heating. The response to additional heating power is determined by the role of ideal or resistive MHD in triggering the sawtooth crash. For plasma shapes where additional heating and consequently, a faster increase of the central pressure shortens the sawteeth, the low experimental limit of the pressure gradient within the q = 1 surface is consistent with ideal MHD predictions. The

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-15

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

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

International Nuclear Information System (INIS)

Kobayashi, Junichi

1979-01-01

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

Differential field equations for the MHD waves and wave equation of Alfven; Las ecuaciones diferenciales de campo para las ondas MHD y la ecuacion de onda de Alfven

Energy Technology Data Exchange (ETDEWEB)

Fierros Palacios, Angel [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

2001-02-01

In this work the complete set of differential field equations which describes the dynamic state of a continuos conducting media which flow in presence of a perturbed magnetic field is obtained. Then, the thermic equation of state, the wave equation and the conservation law of energy for the Alfven MHD waves are obtained. [Spanish] Es este trabajo se obtiene el conjunto completo de ecuaciones diferenciales de campo que describen el estado dinamico de un medio continuo conductor que se mueve en presencia de un campo magnetico externo perturbado. Asi, se obtiene la ecuacion termica de estado, la ecuacion de onda y la ley de la conservacion de la energia para las ondas de Alfven de la MHD.

MHD power conversion employing liquid metals

International Nuclear Information System (INIS)

Houben, J.W.M.A.; Massee, P.

1969-02-01

The work performed in the field of MHD generation of electricity by means of liquid metals is described. It is shown that the study of two-phase flows is essential in this topic of research; two-phase flows are therefore described. Two types of generators which can be utilized with liquid metals have been studied. The results of this study are described. A short survey of the prospects of other liquid metal systems which emerge from a study of the literature is given. Finally, conclusions are drawn concerning possibilities for further investigation

The application of finite element method for mhd viscous flow over a porous stretching sheet

International Nuclear Information System (INIS)

Mahmood, R.; Sajid, M.

2007-01-01

This work is concerned with the magnetohydrodynamic (MHD) viscous flow due to a porous stretching sheet. The similarity solution of the problem is obtained using finite element method. The physical quantities of interest like the fluid velocity and skin friction coefficient is obtained and discussed under the influence of suction parameter and Hartman number. It is evident from the results that MHD can be used to control the boundary layer thickness. (author)

3-D resistive MHD calculations for tokamak plasmas: beyond the simple reduced set of equations

International Nuclear Information System (INIS)

Carreras, B.A.; Garcia, L.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.; Masden, B.F.

1983-01-01

Numerical studies of the resistive stability of tokamak plasmas in cylindrical geometry have been performed using: (1) the full set of resistive Magnetohydrodynamic (MHD) equations and (2) an extended version of the reduced set of resistive MHD equations including diamagnetic and electron temperature effects. In particular, the nonlinear interaction of tearing modes of many helicities has been investigated. The numerical results confirm many of the features uncovered previously using the simple reduced equations. (author)

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

Science.gov (United States)

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

2014-10-01

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

A nonlinear structural subgrid-scale closure for compressible MHD. I. Derivation and energy dissipation properties

Energy Technology Data Exchange (ETDEWEB)

Vlaykov, Dimitar G., E-mail: Dimitar.Vlaykov@ds.mpg.de [Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Max-Planck-Institut für Dynamik und Selbstorganisation, Am Faßberg 17, D-37077 Göttingen (Germany); Grete, Philipp [Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Schmidt, Wolfram [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany); Schleicher, Dominik R. G. [Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160-C (Chile)

2016-06-15

Compressible magnetohydrodynamic (MHD) turbulence is ubiquitous in astrophysical phenomena ranging from the intergalactic to the stellar scales. In studying them, numerical simulations are nearly inescapable, due to the large degree of nonlinearity involved. However, the dynamical ranges of these phenomena are much larger than what is computationally accessible. In large eddy simulations (LESs), the resulting limited resolution effects are addressed explicitly by introducing to the equations of motion additional terms associated with the unresolved, subgrid-scale dynamics. This renders the system unclosed. We derive a set of nonlinear structural closures for the ideal MHD LES equations with particular emphasis on the effects of compressibility. The closures are based on a gradient expansion of the finite-resolution operator [W. K. Yeo (CUP, 1993)] and require no assumptions about the nature of the flow or magnetic field. Thus, the scope of their applicability ranges from the sub- to the hyper-sonic and -Alfvénic regimes. The closures support spectral energy cascades both up and down-scale, as well as direct transfer between kinetic and magnetic resolved and unresolved energy budgets. They implicitly take into account the local geometry, and in particular, the anisotropy of the flow. Their properties are a priori validated in Paper II [P. Grete et al., Phys. Plasmas 23, 062317 (2016)] against alternative closures available in the literature with respect to a wide range of simulation data of homogeneous and isotropic turbulence.

Ideal MHD stability and characteristics of edge localized modes on CFETR

Science.gov (United States)

Li, Ze-Yu; Chan, V. S.; Zhu, Yi-Ren; Jian, Xiang; Chen, Jia-Le; Cheng, Shi-Kui; Zhu, Ping; Xu, Xue-Qiao; Xia, Tian-Yang; Li, Guo-Qiang; Lao, L. L.; Snyder, P. B.; Wang, Xiao-Gang; the CFETR Physics Team

2018-01-01

Investigation on the equilibrium operation regime, its ideal magnetohydrodynamics (MHD) stability and edge localized modes (ELM) characteristics is performed for the China Fusion Engineering Test Reactor (CFETR). The CFETR operation regime study starts with a baseline scenario (R  =  5.7 m, B T  =  5 T) derived from multi-code integrated modeling, with key parameters {{β }N},{{β }T},{{β }p} varied to build a systematic database. These parameters, under profile and pedestal constraints, provide the foundation for the engineering design. The long wavelength low-n global ideal MHD stability of the CFETR baseline scenario, including the wall stabilization effect, is evaluated by GATO. It is found that the low-n core modes are stable with a wall at r/a  =  1.2. An investigation of intermediate wavelength ideal MHD modes (peeling ballooning modes) is also carried out by multi-code benchmarking, including GATO, ELITE, BOUT++ and NIMROD. A good agreement is achieved in predicting edge-localized instabilities. Nonlinear behavior of ELMs for the baseline scenario is simulated using BOUT++. A mix of grassy and type I ELMs is identified. When the size and magnetic field of CFETR are increased (R  =  6.6 m, B T  =  6 T), collisionality correspondingly increases and the instability is expected to shift to grassy ELMs.

RFX: New tools for real-time MHD control

International Nuclear Information System (INIS)

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

2005-01-01

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

Observation of finite-β MHD phenomena in Tokamaks

International Nuclear Information System (INIS)

McGuire, K.M.

1985-01-01

Stable high beta plasmas are required for the tokamak to attain an economical fusion reactor. Recently, intense neutral beam heating experiments in tokamaks have shown new effects on plasma stability and confinement associated with high beta plasmas. The observed spectrum of MHD fluctuations at high beta is clearly dominated by the n = 1 mode when the q = 1 surface is in the plasma. The m/n = 1/1 mode drives other n = 1 modes through toroidal coupling and n > 1 modes through nonlinear coupling. On PDX, with near perpendicular injection, a resonant interaction between the n = 1 internal kink and the trapped fast ions results in loss of beam particles and heating power. Key parameters in the theory are the value of qsub(o) and the injection angle. High frequency broadband magnetic fluctuations have been observed on ISX-B and D-III and a correlation with the deterioration of plasma confinement was reported. During enhanced confinement (H-mode) discharges in divertor plasmas two new edge instabilities were observed, both localized radially near the separatrix. By assembling results from the different tokamak experiments, it is found that the simple theoretical ideal MHD beta limit has not been exceeded

Numerical Calculation of the Output Power of a MHD Generator

Directory of Open Access Journals (Sweden)

Adrian CARABINEANU

2014-12-01

Full Text Available Using Lazăr Dragoş’s analytic solution for the electric potential we perform some numerical calculations in order to find the characteristics of a Faraday magnetohydrodymamics (MHD power generator (total power, useful power and Joule dissipation power.

Modified NASA-Lewis chemical equilibrium code for MHD applications

Science.gov (United States)

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

1979-01-01

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

MHD simulation of high wavenumber ballooning-like modes in LHD

International Nuclear Information System (INIS)

Miura, H.; Nakajima, N.

2008-10-01

Dynamical growths of high-wavenumber ballooning modes are studied through full-3D nonlinear MHD simulations of the Large Helical Device. The growths of the ballooning modes are identified by studying the growth rates and the radial profiles of the Fourier coefficients of fluctuation variables. The mechanisms to weaken the growth of instability, such as the local fattening of the pressure and the energy release to the parallel kinetic energy, are found being insufficient to suppress the high-wavenumber ballooning modes. Consequently, the mean pressure profile is totally modified when the evolutions of the ballooning modes are saturated. The numerical results reveal that we need some mechanisms which do not originate from an ideal MHD to achieve a mild, saturated behaviors beyond the growths of unstable high ballooning modes in the helical device. The parallel heat conductivity is proposed as one of possible non-ideal mechanisms. (author)

Impulsive relaxation process in MHD driven reconnection

International Nuclear Information System (INIS)

Kitabata, H.; Hayashi, T.; Sato, T.

1997-01-01

Compressible magnetohydrodynamic (MHD) simulation is carried out in order to investigate energy relaxation process of the driven magnetic reconnection in an open finite system through a long time calculation. It is found that a very impulsive energy release occurs in an intermittent fashion through magnetic reconnection for a continuous magnetic flux injection on the boundary. We focus our attention on the detailed process in the impulsive phase, which is the reconnection rate is remarkably enhanced up. (author)

Space potential fluctuations during MHD activities in the Compact Helical System (CHS)

International Nuclear Information System (INIS)

Iguchi, H.; Fujisawa, A.; Crowley, T.P.

1998-02-01

Local space potential fluctuations have been measured during MHD activities in a low-beta NBI heated plasma in the Compact Helical System (CHS) by the use of a heavy ion beam probe (HIBP). Two types of MHD modes with accompanying potential oscillations are observed. One appears in periodic bursts with relatively low frequency (< 40 kHz) and large amplitude (20-40 volts), and is localized around the q=2 surface (average minor radius ρ ∼ 0.7). The other appears in continuous and coherent oscillation with higher frequency (105-125 kHz) and smaller amplitude (∼5 volts). This oscillation also has spatial structure. Possible interpretation for the space potential oscillations is presented. (author)

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

African Journals Online (AJOL)

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

Final Report for 'Implimentation and Evaluation of Multigrid Linear Solvers into Extended Magnetohydrodynamic Codes for Petascale Computing'

International Nuclear Information System (INIS)

Vadlamani, Srinath; Kruger, Scott; Austin, Travis

2008-01-01

Extended magnetohydrodynamic (MHD) codes are used to model the large, slow-growing instabilities that are projected to limit the performance of International Thermonuclear Experimental Reactor (ITER). The multiscale nature of the extended MHD equations requires an implicit approach. The current linear solvers needed for the implicit algorithm scale poorly because the resultant matrices are so ill-conditioned. A new solver is needed, especially one that scales to the petascale. The most successful scalable parallel processor solvers to date are multigrid solvers. Applying multigrid techniques to a set of equations whose fundamental modes are dispersive waves is a promising solution to CEMM problems. For the Phase 1, we implemented multigrid preconditioners from the HYPRE project of the Center for Applied Scientific Computing at LLNL via PETSc of the DOE SciDAC TOPS for the real matrix systems of the extended MHD code NIMROD which is a one of the primary modeling codes of the OFES-funded Center for Extended Magnetohydrodynamic Modeling (CEMM) SciDAC. We implemented the multigrid solvers on the fusion test problem that allows for real matrix systems with success, and in the process learned about the details of NIMROD data structures and the difficulties of inverting NIMROD operators. The further success of this project will allow for efficient usage of future petascale computers at the National Leadership Facilities: Oak Ridge National Laboratory, Argonne National Laboratory, and National Energy Research Scientific Computing Center. The project will be a collaborative effort between computational plasma physicists and applied mathematicians at Tech-X Corporation, applied mathematicians Front Range Scientific Computations, Inc. (who are collaborators on the HYPRE project), and other computational plasma physicists involved with the CEMM project.

A civil engineering approach to ideal MHD

International Nuclear Information System (INIS)

Jensen, V.O.

1992-01-01

It is well known that a magnetic field can be conceived as a medium where an isotropic compressive stress, B 2 /2μ 0 , is superimposed on a tensile stress, B 2 /μ 0 , parallel to the lines of force. When a stationary ideal MHD plasma is present in the magnetic field, the particle pressure adds to the magnetic stresses to form a combined stress tensor. Calculations of plasma equilibria based on this concept are very similar to calculations in civil engineering of static structures based on compressive, tensile, and shear stresses. Therefore the very simple physical pictures known from civil engineering when used in plasma physics provide simple physical understanding and facilitate the physical interpretation of the results. In an earlier paper the concept was used to derive and discuss the equilibrium equations for θ-, Z-, and screw pinches and the Grad-Shafranov shift in a tokamak plasma with circular cross sections of the flux surfaces. Here the concept is used to discuss the virial theorem and to obtain a simple physical interpretation of this theorem. We also reconsider the Grad-Shafranov shift in a tokamak plasma and show that a situation where all flux surfaces have circular cross sections cannot be an exact solution to the ideal MHD equations. (author) 3 refs., 3 figs

An Iterative Interplanetary Scintillation (IPS) Analysis Using Time-dependent 3-D MHD Models as Kernels

Science.gov (United States)

Jackson, B. V.; Yu, H. S.; Hick, P. P.; Buffington, A.; Odstrcil, D.; Kim, T. K.; Pogorelov, N. V.; Tokumaru, M.; Bisi, M. M.; Kim, J.; Yun, J.

2017-12-01

The University of California, San Diego has developed an iterative remote-sensing time-dependent three-dimensional (3-D) reconstruction technique which provides volumetric maps of density, velocity, and magnetic field. We have applied this technique in near real time for over 15 years with a kinematic model approximation to fit data from ground-based interplanetary scintillation (IPS) observations. Our modeling concept extends volumetric data from an inner boundary placed above the Alfvén surface out to the inner heliosphere. We now use this technique to drive 3-D MHD models at their inner boundary and generate output 3-D data files that are fit to remotely-sensed observations (in this case IPS observations), and iterated. These analyses are also iteratively fit to in-situ spacecraft measurements near Earth. To facilitate this process, we have developed a traceback from input 3-D MHD volumes to yield an updated boundary in density, temperature, and velocity, which also includes magnetic-field components. Here we will show examples of this analysis using the ENLIL 3D-MHD and the University of Alabama Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS) heliospheric codes. These examples help refine poorly-known 3-D MHD variables (i.e., density, temperature), and parameters (gamma) by fitting heliospheric remotely-sensed data between the region near the solar surface and in-situ measurements near Earth.

Fully developed MHD turbulence near critical magnetic Reynolds number

International Nuclear Information System (INIS)

Leorat, J.; Pouquet, A.; Frisch, U.

1981-01-01

Liquid-sodium-cooled breeder reactors may soon be operating at magnetic Reynolds numbers Rsup(M) where magnetic fields can be self-excited by a dynamo mechanism. Such flows have kinetic Reynolds numbers Rsup(V) of the order of 10 7 and are therefore highly turbulent. The behaviour of MHD turbulence with high Rsup(V) and low magnetic Prandtl numbers is investigated, using the eddy-damped quasi-normal Markovian closure applied to the MHD equations. For simplicity the study is restricted to homogeneous and isotropic turbulence, but includes helicity. A critical magnetic Reynolds number Rsub(c)sup(M) of the order of a few tens (non-helical case) is obtained above which magnetic energy is present. Rsub(c)sup(M) is practically independent of Rsup(V) (in the range 40 to 10 6 ) and can be considerably decreased by the presence of helicity. No attempt is made to obtain quantitative estimates for a breeder reactor, but discuss some of the possible consequences of exceeding Rsub(c)sup(M) such as decreased turbulent heat transport. (author)