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Fifth-order aberrations in magnetic quadrupole-octupole systems

Description: Explicit integral expressions are given for the fifth-order geometrical aberration coefficients in rectilinear magnetic quadrupole-octupole systems used for the transport of nonrelativistic charged particle beams. The numerical values of the fifth-order geometrical aberration coefficients for a rare earth cobalt (REC) quadrupole doublet are given as an example. 26 refs., 5 figs., 4 tabs.
Date: January 1, 1990
Creator: Ling, K. M.
Partner: UNT Libraries Government Documents Department

Analytic solutions of del x B =. cap alpha. B in a straight cylinder with. cap alpha. =. cap alpha. (r)

Description: Analytic solutions of del x B = ..cap alpha..B are presented for reversed field pinch (RFP) configurations in a straight cylinder with ..cap alpha.. = ..cap alpha..(r) where r is the radial coordinate. The function ..cap alpha..(r) is a smooth function of r vanishing at the wall (r = a). Closed form parametric formulas for a family of F-THETA curves are obtained from the analytic, cylindrically symmetric, force-free fields. These formulas can be used to fit experimental F-THETA curves and hence facilitate comparison between the various existing RFP experiments. The advantage of these formulas lies in the fact that they are expressed in terms of easily obtainable Bessel functions of the first kind, eliminating the need of mumerical integration. Results of the least-square fits of two typical ZT-40M shots are presented.
Date: June 1, 1985
Creator: Ling, K.M. & Baker, D.A.
Partner: UNT Libraries Government Documents Department

Princeton spectral equilibrium code: PSEC

Description: A fast computer code has been developed to calculate free-boundary solutions to the plasma equilibrium equation that are consistent with the currents in external coils and conductors. The free-boundary formulation is based on the minimization of a mean-square error epsilon while the fixed-boundary solution is based on a variational principle and spectral representation of the coordinates x(psi,theta) and z(psi,theta). Specific calculations using the Columbia University Torus II, the Poloidal Divertor Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR) geometries are performed.
Date: March 1, 1984
Creator: Ling, K.M. & Jardin, S.C.
Partner: UNT Libraries Government Documents Department

Tokamak fusion reactor start-up simulation

Description: A simulation code TSEC (Time-dependent Spectral Equilibrium Code) has been developed to model the axisymmetric evolution of a tokamak on the resistive (L/R) time scale of the external coils, conductors, or shell. The electromagnetic interaction between the plasma and the external circuit is taken into account in a self-consistent manner. TSEC is Lagrangian and utilizes magnetic flux coordinates with spectral decomposition in the angle variable theta. The plasma is modeled as a finite-size, zero-inertia, finite-pressure fluid which adjusts its position and shape to remain in free-boundary equilibrium consistent with the currents in the external circuits. At the heart of TSEC is a fast method of calculating the self-consistent free-boundary plasma equilibrium at each time step which is based on the minimization of a certain mean-square error. 3 refs., 6 figs., 3 tabs.
Date: February 1, 1986
Creator: Ling, K.M.; Jardin, S.C. & Perkins, F.W.
Partner: UNT Libraries Government Documents Department

Theoretical and experimental studies of field-reversed configurations

Description: The FRX-C/T formation region has been enlarged in diameter by 50%, and quasi-steady cusp coils have been installed to compare tearing and non-tearing formation. FRCs with significantly larger poloidal flux (less than or equal to8 mWb) and s (less than or equal to4) have been formed. However, their flux confinement was degraded compared with earlier FRX-C results. The n = 2 rotational instability has been completely suppressed on translated FRCs in FRX-C/T. Nearly equal stabilization thresholds were observed for straight and helical quadrupole fields, in contrast with another experiment.
Date: January 1, 1986
Creator: Chrien, R. E.; Hugrass, W. N.; Armstrong, W. T.; Caramana, E. J.; Lewis, H. R.; Linford, R. K. et al.
Partner: UNT Libraries Government Documents Department