@misc{oai:ir.soken.ac.jp:00000541,
 author = {CHOWDHURI, Malay Bikas and チョードリ, マレイビカス and CHOWDHURI, Malay Bikas},
 month = {2016-02-17, 2016-02-17},
 note = {Impurity control is one of crucial problems to be solved in fusion research. The<br />extreme ultraviolet (EUV) spectroscopy gives a major diagnostic technique to monitor<br />and study the impurity behavior in magnetically confined fusion plasmas. For the<br />purpose, two flat-field EUV spectrometers for impurity diagnostics in 10-130 and<br />50-500&Aring; ave been developed with varied-line-spacing (VLS) laminar-type<br />holographic gratings. The spectral characteristics obtained from the holographic gratings　were compared with ones from conventional ruled gratings and excellent property was found in the holographic gratings, i.e., negligibly low level of stray light and higher-order emission intensity. The EUV spectrometers have been absolutely calibrated using a new technique based on the combination of EUV bremsstrahlung and branching ratio. EUV spectra have been thus successfully observed from high-temperature plasmas in Large Helical Device (LHD) and several EUV line emissions of Ti, Fe, Mo and W have been analyzed and identified in detailed for the purpose of further development of the impurity diagnostics.<br />　　　The edge impurity transport in intrinsically existing ergodic layer of LHD, where<br />the transport parallel to magnetic fields is relatively dominant, has been studied through<br />the observation of carbon emissions. Four resonance transitions of CIII (977&Aring;: 2s2p<br /><sup>1</sup>P<small>1</small>-2s<sup>2</sup> <sup>1</sup>S<small>0</small>), CIV (1548&Aring : 2p <sup>2</sup>P-2s <sup>2</sup>S), CV (40.27&Aring;: 1s2p <sup>1</sup>P<small>1</small>-<sup>1</sup>s<sup>2</sup> <sup>1</sup>S<small>0</small>) and CVI<br />(33.73&Aring;: 2p <sup>2</sup>P-1s <sup>2</sup>S) have been observed with the EUV spectrometers and 20cm normal incidence VUV spectrometers. The ratio of CV+CVI to CIII+CIV has been analyzed in a variety of magnetic configurations and plasma parameters. The impurity screening was evidently observed and the physical mechanism on the impurity transport given by the edge stochastic magnetic fields has been discussed with the thermal force and friction force. The modeling of the edge impurity transport with EMC3+EIRENE simulation code strongly suggests the importance of the friction force for the enhancement of the impurity screening. The density dependence of the measured ratio indicating the impurity screening effect is in good agreement with the modeling result., 総研大甲第1191号},
 title = {Development of flat-field EUV spectrometers with absolute calibration and study of impurity behabior in edge plasmas on LHD},
 year = {}
}