Fully non-inductive plasma start-up was successfully achieved by using a well- controlled microwave source on the spherical tokamak, QUEST. Non-inductive plasmas were maintained for approximately 3-5 min, during which...Fully non-inductive plasma start-up was successfully achieved by using a well- controlled microwave source on the spherical tokamak, QUEST. Non-inductive plasmas were maintained for approximately 3-5 min, during which time power balance estimates could be achieved by monitoring wall and cooling-water temperatures. Approximately 70%-90% of the injected power could be accounted for by calorimetric measurements and approximately half of the injected power was found to be deposited on the vessel wall, which is slightly dependent on the magnetic configuration. The power distribution to water-cooled limiters, which are expected to be exposed to local heat loads, depends significantly on the magnetic configuration, however some of the deposited power is due to energetic electrons, which have large poloidal orbits and are likely to be deposited on the plasma facing components.展开更多
Two-dimensional structure of density fluctuations is examined during the current jump phase, indicating a change from the open magnetic fields to the closed ones. During the smooth current ramp-up phase the two-dimens...Two-dimensional structure of density fluctuations is examined during the current jump phase, indicating a change from the open magnetic fields to the closed ones. During the smooth current ramp-up phase the two-dimensional contour of the LiI intensity shows vertically alignment, consistent with the magnetic surfaces. At the inflection point in Ip ramp-up the LiI intensity contour becomes flat in the observation regime and then suddenly a steep gradient and higher intensity regime are formed in the vertical direction. This higher intensity corresponds to a burst of LiI waveform. According to these changes in the contour, it is found that, within ~1 ms around the burst of LiI, a low frequency coherent wave with a long wavelength rapidly grows. The relations with other signals （magnetic flux and microwave stray power） are discussed with respect to the topological change in the magnetic configuration and mode conversion of the incident electromagnetic waves.展开更多
基金supported by Grant-in-Aid for JSPS Fellows(KAKENHI Grant Number 16H02441,24656559)performed with the support and under the auspices of the NIFS Collaboration Research Program(NIFS05KUTRO14,NIFS11KUTR061,NIFS13KUTR085,NIFS14KUTR103)+1 种基金supported in part by the Collaborative Research Program of the Research Institute for Applied Mechanics,Kyushu Universitypartly supported by the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(No.11261140328)
文摘Fully non-inductive plasma start-up was successfully achieved by using a well- controlled microwave source on the spherical tokamak, QUEST. Non-inductive plasmas were maintained for approximately 3-5 min, during which time power balance estimates could be achieved by monitoring wall and cooling-water temperatures. Approximately 70%-90% of the injected power could be accounted for by calorimetric measurements and approximately half of the injected power was found to be deposited on the vessel wall, which is slightly dependent on the magnetic configuration. The power distribution to water-cooled limiters, which are expected to be exposed to local heat loads, depends significantly on the magnetic configuration, however some of the deposited power is due to energetic electrons, which have large poloidal orbits and are likely to be deposited on the plasma facing components.
基金the NIFS Collaboration Research Program (NIFS07KOAR009,NIFS05KUTR012)the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘Two-dimensional structure of density fluctuations is examined during the current jump phase, indicating a change from the open magnetic fields to the closed ones. During the smooth current ramp-up phase the two-dimensional contour of the LiI intensity shows vertically alignment, consistent with the magnetic surfaces. At the inflection point in Ip ramp-up the LiI intensity contour becomes flat in the observation regime and then suddenly a steep gradient and higher intensity regime are formed in the vertical direction. This higher intensity corresponds to a burst of LiI waveform. According to these changes in the contour, it is found that, within ~1 ms around the burst of LiI, a low frequency coherent wave with a long wavelength rapidly grows. The relations with other signals （magnetic flux and microwave stray power） are discussed with respect to the topological change in the magnetic configuration and mode conversion of the incident electromagnetic waves.
