Search Results

Advanced search parameters have been applied.
open access

Excitation of internal kink modes by trapped energetic beam ions

Description: Energetic trapped particles are shown to have a destabilizing effect on the internal kink mode in tokamaks. The plasma pressure threshold for the mode is lowered by the particles. The growth rate is near the ideal magnetohydrodynamic value, but the frequency is comparable to the trapped particle precission frequency. A model for the instability cycle gives stability properties, associated particle losses, and neutron emissivity consistent with the fishbone events observed in PDX.
Date: October 1, 1983
Creator: Chen, L.; White, R. B. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Stability of the Pinch

Description: In this report, the stability of a pinched fluid is studied theoretically, under the combined influence of a longitudinal magnetic field and conducting exterior shell. Conditions allowing complete stability are found.
Date: April 1956
Creator: Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Solving the Chirikov Taylor Model by the Method of Paths in Fourier Space

Description: A compact path-diagram method has been introduced for the calculation of velocity moments of a probability function. This method is complementory to the approach developed earlier. It is applied to the Chirikov-Taylor model. A number of new results have been derived and verified by numerical computations.
Date: July 1, 1980
Creator: Rechester, A. B.; Rosenbluth, M. N. & White, R. B.
Partner: UNT Libraries Government Documents Department
open access

Simulation of a major tokamak disruption

Description: It is known that the internal tokamak disruption leads to a current profile which is flattened inside the surface where the safety factor equals unity. It is shown that such a profile can lead to m = 2 magnetic islands which grow to fill a substantial part of the tokamak cross section in a time consistent with the observations of the major disruption.
Date: August 1, 1977
Creator: White, R. B.; Monticello, D. A. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Feedback stabilization of magnetic islands in tokamaks

Description: The major tokamak disruption limits the operation of present tokamaks, and present experimental evidence points to the m = 2, n = 1 tearing mode as being primarily responsible for its occurrence. Numerical codes capable of following the full nonlinear history of this mode have been used to develop and test feedback stabilization schemes utilizing helical coils mounted on the interior of the tokamak wall. It is found that a phase detecting feedback system is capable of stabilizing the magnetic i… more
Date: September 1, 1978
Creator: Monticello, D. A.; White, R. B. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Filamentation of a converging heavy ion beam

Description: A major concern in the use of heavy ion beams as igniters in pellet fusion systems is the vulnerability of the beam to the transverse flamentation instability. The undesirable consequence of this mode is the transverse heating of the beam to the extent that convergence on the pellet becomes impossible. This work considers the case of a beam injected into a gas filled reactor vessel, where finite pulse length and propagation distance play an important role in limiting growth. Two geometries are … more
Date: February 4, 1980
Creator: Lee, E. P.; Buchanan, H. L. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

COMPREHENSIVE GYROKINETIC SIMULATION OF TOKAMAK TURBULENCE AT FINITE RELATIVE GYRORADIUS

Description: OAK B202 COMPREHENSIVE GYROKINETIC SIMULATION OF TOKAMAK TURBULENCE AT FINITE RELATIVE GYRORADIUS. A continuum global gyrokinetic code GYRO has been developed to comprehensively simulate turbulent transport in actual experimental profiles and allow direct quantitative comparisons to the experimental transport flows. GYRO not only treats the now standard ion temperature gradient (ITG) mode turbulence, but also treats trapped and passing electrons with collisions and finite beta, and all in real … more
Date: September 1, 2002
Creator: Waltz, R. E.; Candy, J. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Investigations in Anomalous Transport and Ignition Physics. Annual Summary of Progress, November 1995--November 1996

Description: During FY 95, research supported by DOE Grant No. DE-FG03-88ER53275 has focused on confinement enhancement by reversed shear, core transport physics, L {yields} H transition theory, and the general theory of plasma dynamics. This report discusses specific accomplishments and lists future plans.
Date: August 1, 1996
Creator: Diamond, P. H. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Numerical studies of nonlinear evolution of kink modes in tokamaks

Description: A set of numerical techniques for investigating the full nonlinear unstable behavior of low-..beta.. kink modes of given helical symmetry in tokamaks is presented. Uniform current density plasmas display complicated deformations including the formation of large vacuum bubbles provided that the safety factor q is sufficiently close to integral. Fairly large m = 1 deformations, but not bubble formation, persist for a plasma with a parabolic current density profile (and hence shear). Deformations … more
Date: November 1, 1975
Creator: Rosenbluth, M. N.; Monticello, D. A.; Strauss, H. & White, R. B.
Partner: UNT Libraries Government Documents Department
open access

Nonlinear tearing modes in tokamaks

Description: Numerical codes have been developed for the description of the nonlinear evolution of tearing modes in tokamaks. The m = 1 mode is observed to continue rapid growth in the nonlinear regime, producing significant changes on a time scale consistent with the experimentally observed minor disruption. The double tearing mode associated with a hollow current profile also continues rapid growth in the nonlinear regime, and thus may play a significant role in the anomalous current penetration during th… more
Date: September 1, 1976
Creator: White, R. B.; Monticello, D. A.; Rosenbluth, M. N. & Waddell, B. V.
Partner: UNT Libraries Government Documents Department
open access

Curvature-driven instabilities in a hot-electron plasma: radial analysis

Description: The theory of unfavorable curvature-driven instabilities is developed for a plasma interacting with a hot electron ring whose drift frequencies are larger than the growth rates predicted from conventional magnetohydrodynamic theory. A z-pinch model is used to emphasize the radial structure of the problem. Stability criteria are obtained for the five possible modes of instability: the conventional hot electron interchange, a high-frequency hot electron interchange (at frequencies larger than the… more
Date: December 1, 1981
Creator: Berk, H. L.; Van Dam, J. W.; Rosenbluth, M. N. & Spong, D. A.
Partner: UNT Libraries Government Documents Department
open access

Modification of the tearing mode growth rate by the presence of a stochastic magnetic field

Description: We have studied the effect of a stochastic magnetic field on the growth of a tearing mode. An analytic solution is given for the case in which the stochastic magnetic field is static. In that case, an unstable tearing mode is further destabilized (stabilized) if the ..delta..' values of the nonlinearly driven modes are positive (negative). This mechanism explains the destabilization of the (m = 3; n = 2) tearing mode observed in nonlinear three-dimensional calculations.
Date: December 1, 1980
Creator: Carreras, B. A.; Rosenbluth, M. N. & Hicks, H. R.
Partner: UNT Libraries Government Documents Department
open access

Dynamics of axisymmetric E x B and poloidal flows in tokamaks

Description: As a result of turbulence and finite Larmor radius effects, random radial currents are present in a tokamak plasma, and these drive sheared axisymmetric poloidal flows. The authors model these currents with a noise source with given statistical properties and calculate the linear kinetic response to this source. Without collisions, there is no long term damping of these flows; when collisions are included, poloidal flows are damped. The mean square potential associated with these flows is given… more
Date: July 1, 1998
Creator: Hinton, F. L. & Rosenbluth, M. N.
Partner: UNT Libraries Government Documents Department
open access

Nonlinear saturation of the dissipative trapped-electron instability

Description: It is shown that trapped-electron induced scattering can be dominant over nonlinear ion Landau damping in the saturation of short-wavelength dispersive trapped-electron instabilities in tokamaks. Trapped-electron induced scattering transfers the wave energy to shorter wavelengths, where it can be dissipated by ion viscosity.
Date: March 1, 1977
Creator: Chen, L.; Berger, R. L.; Lominadze, J. G.; Rosenbluth, M. N. & Rutherford, P. H.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen