46 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Thermonuclear Devices 700105* -- Fusion Energy-- Plasma Research-- Plasma Kinetics-Theoretical-- -1987"  
Results: 1 - 24 next
open access

Hot-electron-ring physics

Description: Separate abstracts were prepared for each of the 16 included papers. (MOW)
Date: June 1, 1982
Creator: Uckan, N.A. (ed.)
Partner: UNT Libraries Government Documents Department
open access

Computer simulations of anomalous transport

Description: Numerical plasma simulations have been carried out to study: (1) the turbulent spectrum and anomalous plasma transport associated with a steady state electrostatic drift turbulence; and (2) the anomalous energy transport of electrons due to shear-Alfven waves in a finite-..beta.. plasma. For the simulation of the steady state drift turbulence, it is observed that, in the absence of magnetic shear, the turbulence is quenched to a low level when the rotational transform is a rational number, whil… more
Date: July 1, 1980
Creator: Lee, W. W. & Okuda, H.
Partner: UNT Libraries Government Documents Department
open access

Large aspect ratio tokamak study

Description: The Large Aspect Ratio Tokamak Study (LARTS) investigated the potential for producing a viable long burn tokamak reactor through enhanced volt-second capability of the ohmic heating transformer by employing high aspect ratio designs. The plasma physics, engineering, and economic implications of high aspect ratio tokamaks were accessed in the context of extended burn operation. Plasma startup and burn parameters were addressed using a one-dimensional transport code. The pulsed electrical power r… more
Date: January 1, 1979
Creator: Reid, R. L.; Holmes, J. A.; Houlberg, W. A.; Peng, Y. K. M.; Strickler, D. J.; Brown, T. G. et al.
Partner: UNT Libraries Government Documents Department
open access

Preliminary semiempirical transport models

Description: A class of semiempirical transport models is proposed for testing against confinement data from tokamaks and for use in operations planning and machine design. A reference model is proposed to be compatible with published confinement data. Theoretical considerations are used to express the anomalous transport coefficients in terms of appropriate dimensionless parameters.
Date: November 1, 1983
Creator: Singer, C.E.
Partner: UNT Libraries Government Documents Department
open access

Three-dimensional free boundary calculations using a spectral Green's function method

Description: The plasma energy W/sub p/ = integral ..cap omega../sub p/(1/2B/sup 2/ + p)dV is minimized over a toroidal domain ..cap omega../sub p/ using an inverse representation for the cylindrical coordinates R = ..sigma..R/sub mn/(s)cos(mtheta - n zeta) and Z = ..sigma..Z/sub mn/(s)sin(mtheta - n zeta), where (s,theta,zeta) are radial, poloidal, and toroidal flux coordinates, respectively. The radial resolution of the MHD equations is significantly improved by separating R and Z into contributions from … more
Date: January 1, 1986
Creator: Hirshman, S.P.; van Rij, W.I. & Merkel, P.
Partner: UNT Libraries Government Documents Department
open access

Hydrogen recycle modeling in transport codes

Description: The hydrogen recycling models now used in Tokamak transport codes are reviewed and the method by which realistic recycling models are being added is discussed. Present models use arbitrary recycle coefficients and therefore do not model the actual recycling processes at the wall. A model for the hydrogen concentration in the wall serves two purposes: (1) it allows a better understanding of the density behavior in present gas puff, pellet, and neutral beam heating experiments; and (2) it allows … more
Date: January 1, 1979
Creator: Howe, H.C.
Partner: UNT Libraries Government Documents Department
open access

Application of the implicit Fourier-expansion method to the calculation of three-dimensional equilibria by the iterative method

Description: The iterative method of finding solutions to three-dimensional equilibria is discussed. The implicit Fourier-expansion method is briefly described and applied to the linear problems arising in the iterative loops. The paper shows how to efficiently solve for the magnetic field induced by the plasma.
Date: August 1, 1983
Creator: Shestakov, A.I.
Partner: UNT Libraries Government Documents Department
open access

Fokker-Planck/Transport model for neutral beam driven tokamaks

Description: The application of nonlinear Fokker-Planck models to the study of beam-driven plasmas is briefly reviewed. This evolution of models has led to a Fokker-Planck/Transport (FPT) model for neutral-beam-driven Tokamaks, which is described in detail. The FPT code has been applied to the PLT, PDX, and TFTR Tokamaks, and some representative results are presented.
Date: January 1, 1980
Creator: Killeen, J.; Mirin, A. A. & McCoy, M. G.
Partner: UNT Libraries Government Documents Department
open access

Theoretical view of the plasma focus

Description: The present theory of the plasma focus device is discussed. Experiments at low pressure clearly show a disruption of the current sheath and the formation of energetic electron and ion beams in a turbulent medium. Possible directions for calculations to explain this conversion of magnetic energy into charged particle beams are indicated.
Date: February 1, 1980
Creator: Maxon, S.
Partner: UNT Libraries Government Documents Department
open access

Two-point model for electron transport in EBT

Description: The electron transport in EBT is simulated by a two-point model corresponding to the central plasma and the edge. The central plasma is assumed to obey neoclassical collisionless transport. The edge plasma is assumed turbulent and modeled by Bohm diffusion. The steady-state temperatures and densities in both regions are obtained as functions of neutral influx and microwave power. It is found that as the neutral influx decreases and power increases, the edge density decreases while the core dens… more
Date: January 1980
Creator: Chiu, S. C. & Guest, G. E.
Partner: UNT Libraries Government Documents Department
open access

Status of tandem mirror theory

Description: This report contains the text and slides used for the review talk on tandem mirror theory presented at the meeting of the Division of Plasma Physics, A.P.S., Boston, MA, November 12-16, 1979. Topics covered include classical confinement, equilibria, MHD- and micro-stability, radial transport, and thermal barriers.
Date: December 12, 1979
Creator: Baldwin, D.E.
Partner: UNT Libraries Government Documents Department
open access

Two-dimensional magnetohydrodynamic calculations for a 5 MJ plasma focus

Description: The performance of a 5 MJ plasma focus is calculated using our two-dimensional magnetohydrodynamic (2-D MHD) code. Two configurations are discussed, a solid and a hollow anode. In the case of the hollow anode, we find an instability in the current sheath which has the characteristics of the short wave length sausage instability. As the current sheath reaches the axis, the numerical solution is seen to break down. Just before this time, plasma parameters take on the characteristic values rho/rho… more
Date: May 4, 1979
Creator: Maxon, S.
Partner: UNT Libraries Government Documents Department
open access

EBT reactor characteristics consistent with stability and power balance requirements

Description: This paper summarizes the results of a recent EBT reactor study that includes both ring and core plasma properties and consistent treatment of coupled ring-core stability criteria and power balance requirements. The principal finding is that constraints imposed by these coupling and other physics and technology considerations permit a broad operating window for reactor design optimization. A number of concept improvements are also proposed that are found to offer the potential for further impro… more
Date: January 1, 1983
Creator: Uckan, N. A. & Santoro, R. T.
Partner: UNT Libraries Government Documents Department
open access

Neutral-fueling pressure measurements and modeling near the plasma edge in TMX-U

Description: Large variations in pressure from external gas-fueling sources and from plasma-induced wall reflux along the TMX-U plasma have been observed. These pressure variations can produce locally high neutral density in the plasma, which strongly affects the plasma parameters. These local pressure measurements include data from a newly installed neutral-pressure diagnostic system of fast magnetron gauges. The plasma-induced warm-wall reflux has been observed to be primarily HD and H/sub 2/ as opposed t… more
Date: December 3, 1984
Creator: Pickles, W.L.
Partner: UNT Libraries Government Documents Department
open access

Plasma modeling of MFTF-B and the sensitivity to vacuum conditions

Description: The Mirror Fusion Test Facility (MFTF-B) is a large tandem mirror device currently under construction at Lawrence Livermore National Laboratory. The completed facility will consist of a large variety of components. Specifically, the vacuum vessel that houses the magnetic coils is basically a cylindrical vessel 60 m long and 11 m in diameter. The magnetics system consists of some 28 superconducting coils, each of which is located within the main vacuum vessel. Twenty of these coils are relativel… more
Date: September 12, 1984
Creator: Porter, G. D. & Rensink, M.
Partner: UNT Libraries Government Documents Department
open access

Anomalous transport in mirror systems

Description: As now being explored for fusion applications confinement systems based on the mirror principle embody two kinds of plasma regimes. These two regimes are: (a) high-beta plasmas, stabilized against MHD and other low frequency plasma instabilities by magnetic-well fields, but characterized by non-Maxwellian ion distributions; (b) near-Maxwellian plasmas, confined electrostatically (as in the tandem mirror) or in a field-reversed region within the mirror cell. Common to both situations are the que… more
Date: August 20, 1979
Creator: Post, Richard F.
Partner: UNT Libraries Government Documents Department
open access

Three-dimensional equilibrium in quadrupole symmetric tandem mirrors in the paraxial limit (reduced MHD)

Description: Equilibrium in quadrupole symmetric mirrors is fully three dimensional; however, because axial scale lengths are long compared with radial scale lengths (equivalently weak curvature) it is possible to reduce the complexity of the equations by expanding in the appropriate smallness parameter. Such a procedure leads to set of reduced MHD equations. The general theory will be presented, numerical results discussed, modifications due to finite Larmor radius will be added, and an analytic solution f… more
Date: August 29, 1983
Creator: Pearlstein, L.D.
Partner: UNT Libraries Government Documents Department
open access

Plasma engineering analysis of an EBT operating window

Description: The operating space for EBT reactors is calculated using a newly developed systems code that incorporates recent advances in EBT physics. The calculation includes a self-consistent treatment of coupled ring-core stability and power balance requirements. The essential elements of the systems code are reviewed including magnetics, stability, ring power, power balance, confinement time, and cost calculations. Finally, a typical reactor systems analysis is summarized for a family of EBT reactors th… more
Date: January 1, 1983
Creator: Santoro, R. T.; Uckan, N. A. & Barnes, J. M.
Partner: UNT Libraries Government Documents Department
open access

Fokker-Planck equation in mirror research

Description: Open confinement systems based on the magnetic mirror principle depend on the maintenance of particle distributions that may deviate substantially from Maxwellian distributions. Mirror research has therefore from the beginning relied on theoretical predictions of non-equilibrium rate processes obtained from solutions to the Fokker-Planck equation. The F-P equation plays three roles: Design of experiments, creation of classical standards against which to compare experiment, and predictions conce… more
Date: August 11, 1983
Creator: Post, Richard F.
Partner: UNT Libraries Government Documents Department
open access

Magnetics transport aspects of EBTR reactors

Description: The magnetic model developed for the ELMO Bumpy Torus Reactor (EBTR) study is described. A multiple-loop current simulation of toroidal-field (TF) and aspect-ratio-enhancement (ARE) coils is used to calculate the vacuum magnetic field. The bounce-averaged vertical drift velocity, v/sub y/, and poloidal drift frequency, ..cap omega.., are determined from the field topology. Upon performing the appropriate averages of v/sub y/ and ..cap omega.., the point-plasma toroidal curvature, R/sub T/, and … more
Date: January 1, 1981
Creator: Bathke, C. G.
Partner: UNT Libraries Government Documents Department
open access

Numerical simulation of the Beta II experiment

Description: The transport code FRT which is a 1-1/2-D transport-equilibrium code for an axisymmetric plasma was used to simulate the decay of the plasma and magnetic fields of the Beta II experiment. A comparison is made between the experimentally determined decay times for the magnetic fields and particle confinement times and the computed decay times. It is found that 1% oxygen impurity is enough to clamp the electron temperature below the radiation barrier, which is in agreement with the experiment.
Date: October 1, 1981
Creator: Shumaker, D.E.; Boyd, J.K.; McNamara, B. & Turner, W.C.
Partner: UNT Libraries Government Documents Department
open access

Finite orbit treatment of plasma buildup in small mirrors

Description: In a small mirror plasma (R/sub p//rho/sub i/ less than or equal to 40) ion finite gyro-radius (F.G.R.) effects become important, particularly at the surface near the vacuum interface. This is because charge-exchange of incoming cold neutrals (from the injector and recycling off the first wall) occurs primarily in a surface layer only a few centimeters thick, causing plasma erosion. A new 2-1/2-D (1-energy, 1-1/2 spatial) dynamic model now being developed (called FOREMD) extends the F.G.R. trea… more
Date: January 1, 1979
Creator: Campbell, M. & Miley, G.H.
Partner: UNT Libraries Government Documents Department
open access

Physics evaluation of compact tokamak ignition experiments

Description: At present, several approaches for compact, high-field tokamak ignition experiments are being considered. A comprehensive method for analyzing the potential physics operating regimes and plasma performance characteristics of such ignition experiments with O-D (analytic) and 1-1/2-D (WHIST) transport models is presented. The results from both calculations are in agreement and show that there are regimes in parameter space in which a class of small (R/sub o/ approx. 1-2 m), high-field (B/sub o/ a… more
Date: January 1, 1985
Creator: Uckan, N.A.; Houlberg, W.A. & Sheffield, J.
Partner: UNT Libraries Government Documents Department
open access

Monte Carlo particle simulation and finite-element techniques for tandem mirror transport

Description: A description is given of numerical methods used in the study of axial transport in tandem mirrors owing to Coulomb collisions and rf diffusion. The methods are Monte Carlo particle simulations and direct solution to the Fokker-Planck equations by finite-element expansion. 11 refs.
Date: December 1, 1985
Creator: Rognlien, T.D.; Cohen, B.I.; Matsuda, Y. & Stewart, J.J. Jr.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen