Magnetic analysis of ohmic discharges in the superconducting tokamak TRIAM-1M

Abstract

A magnetic analysis to determine the plasma cross-sectional shape and equilibrium parameters in the superconducting tokamak TRIAM-1M is discussed using magnetic data obtained in ohmic discharges. First, it is shown that the eddy currents in the tokamak structures should be taken into account. Two magnetic analysis codes are applied. One is the SHP code in which the plasma current is replaced by several filamental loop currents and the other is the FITEQ code in which the plasma current density is consistent with the MHD equilibrium. The magnetic fields due to eddy currents are expanded into multipole fields. The central safety factor q(0) is fixed at 1.0. The eddy currents reduce the vertical field by 10%. Taking account of them, the accuracy of the magnetic analysis is improved and estimation of the stored thermal energy in a plasma becomes possible. The SHP code has the difficulty that the local plasma surface position can be distorted by the eddy current magnetic field. In addition, it is also noted that the pressure profile analysed by the FITEQ code is consistent with the Thomson scattering measurement and that the energy confinement characteristics are consistent with the neo-Alcator scaling.

On SO(32) heterotic — type I superstring duality in ten dimensions

“…In what follows we shall consider only the trF 4 coupling functions f and f ′ and try to justify (18), (16) and thus the duality relation (15). We shall first argue that f and f ′ should not contain higher-loop corrections and then demonstrate the equality of the coefficients b 1 and b ′ 0 .…”

“…Some of the leading-order coefficients were computed in the past. In the heterotic string theory the tree-level (sphere) coefficients are [12,13,14] b 0 = 0, c 0 = 0 and the one-loop (torus) coefficients in the SO(32) heterotic theory are [15,16,17] b 1 = 0, c 1 = 0. In the type I theory the tree-level (disc) coefficients are [18,19]…”

“…5 It would 3 The double trace (trF 2 trF 2 ) term does appear (i.e. c 1 = 0) in the one-loop action of the E 8 × E 8 heterotic string theory [16] which indeed cannot be directly related to the type I theory. 4 Note that in addition to changing the sign of the dilaton the transformation between the coupling functions of the two theories involves rescaling by the factor e −φ in (13), (14).…”

A new technique to optimize the coil winding path for the arbitrarily distributed magnetic field and application to a helical confinement system

“…The SVD technique has already been used in fusion research for such topics as, poloidal field control, 20 reconstruction of the poloidal field due to eddy currents 21,22 for tokamaks, coil design for a stellarator, 14 and signal processing. 23 These applications were able to improve understanding of those system characteristics.…”

“…23 These applications were able to improve understanding of those system characteristics. 21,22 in which accurate reconstruction of the magnetic field due to eddy currents was crucial and usage of the distribution functions obtained by SVD gave a good reconstruction. The technique developed in this study is an extended version of that in Refs.…”