open access

https://hdl.handle.net/2115/58438

Improved Three-Dimensional CCS Method Analysis for the Reconstruction of the Peripheral Magnetic Field Structure in a Finite Beta Helical Plasma

英語

condition number

2013-11-15

The Japan Society of Plasma Science and Nuclear Fusion Research

Plasma and Fusion Research

8

1402134

In the previous 3D Cauchy-condition surface (CCS) method analysis to reconstruct the magnetic field profile　in the Large Helical Device (LHD), one assumed an impractically large number of magnetic sensors, i.e., 440 field　sensors and 126 flux loops. In the singular value decomposition (SVD) process employed in the CCS method,　a gap is found in the magnitude of the singular values. The most accurate field results can be obtained if all the　singular values smaller than the gap threshold are eliminated, independent of the number of boundary elements　on the CCS and the number of sensors as well. With the reduction in the number of boundary elements, the　required numbers of field sensors and flux loops are significantly reduced to 110 and 25, respectively, without　losing the solution accuracy. They can be further reduced to 58 and 13 respectively if considering the symmetry　of the field profile in the LHD. This result suggests the possibility of actual application to the LHD.

学術雑誌論文

Version of Record

1880-6821