C. Suzuki

K. Ida

M. Emoto

M. Yoshida

Y. Suzuki

National Institute for Fusion Science (NIFS-Repository)

For the analyses of position-dependent experimen-tal data, conversion of real coordinates into magneticcoordinates is important. In LHD, this is achieved by aproper choice of the equilibrium minimizing the discrep-ancy between inboard and outboard sides of the electrontemperature proﬁle. For this purpose, it is necessary toconstruct a database composed of a lot of equilibria.In this work we have developed a new large-scaledatabase for LHD under wide ranges of central beta (p0),pressure peaking factor (pf), plasma current (ip) and cur-rent peaking factor (ipf), which can cover special condi-tions such as strongly peaked pressure proﬁle. Firstlywe have calculated the free-boundary LHD equilibria bythe latest VMEC code, which generates more than 7000equilibria for each vacuum conﬁguration designated bymagnetic axis position (Rax), quadruple magnetic ﬁeld(Bq) and pitch parameter (γ). Then a library routine forthe database access has been developed to run an inversemapping program and get equilibrium parameters suchas eﬀective minor radius, components of magnetic ﬁeld,etc. by giving ten input parameters: real coordinates (R,Z,Φ ), Rax, Bq, γ, p0, pf, ip and ipf. In this routine, anyvalues are allowed as an input and the output parametersare automatically interpolated or extrapolated.Because this process is not fast enough for real-timemapping of all the time frames, we have also prepared”sight database” which tabulates the pre-calculated re-sults of mapping along the selected lines of sights (Thom-son, CXS, FIR, etc.). A function to read the output pa-rameters by designating the name of the sight was addedto the library. In the procedure to search the best-ﬁttedequilibrium from the experimental data, pf and ipf are as-sumed to be appropriate initial values and Rogowski coildata is used for ip. By reading the sight database, errorbetween inboard and outboard side of the electron tem-perature proﬁle is calculated with scanning p0 step bystep for each frame. This procedure is repeated until theminimum error is obtained to determine the best-ﬁttedequilibrium parameters. The other parameters such aselectron kinetic energy, magnetic axis, etc. are calculatedat the same time. After all the frames are processed, theresults are automatically registered as an analyzed datawith a diagnostic name ”tsmap”.Database generation including the sight databasehas been completed for 23 vacuum conﬁgurations. Wehave also developed a viewer program to display Thom-son scattering data in magnetic coordinates. A screen-shot of the viewer program is shown in Fig. 1, wheretime evolutions of several parameters (p0, pf, magneticaxis, electron kinetic energy) for the best-ﬁtted equilib-rium are also displayed.Fig. 1: Screenshot of the viewer program.142§22. Development of Real-Time Magnetic Coordinate Mapping System in LHDSuzuki, C., Ida, K., Suzuki, Y., Yoshida, M.,  Emoto, M.

Development of Real-Time Magnetic Coordinate Mapping System in LHD

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National Institute for Fusion Science (NIFS-Repository)