Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A ...Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A supersonic H2-beam is effectively injected to increase fueling efficiency and generate a peaked density profile. Local fueling with a short-pulsed SMBI can increase the core plasma density and avoid the degradation arising from edge cooling. Second harmonic electron cyclotron current drive （ECCD） experiments were conducted by launching a focused Gaussian beam with a parallel refractive index of -0.05 ≤ Nil 〈 0.6. Results show that the electron cyclotron （EC） driven current is determined not only by Nil but also by local magnetic field （B） structure where the EC power is deposited. Detailed analysis of the observed NI and B dependences is in progress with a ray-tracing simulation using the TRAVIS code. Fast ion velocity distribution was investigated using fast protons generated by ion cyclotron resonant frequency （ICRF） minority heating. For the standard configuration in Heliotron J, charge ex- change neutral particle analysis （CX-NPA） measurements show higher effective temperature of fast minority protons in the on-axis resonance case compared to that in the HFS （high field side） off-axis resonance case. However, the increase in bulk ion temperature in the HFS resonance case is larger than that in the on-axis resonance.展开更多
A heavy ion beam probe （HIBP） using a 3-MV tandem accelerator has been installed on large helical device （LHD）. Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of ...A heavy ion beam probe （HIBP） using a 3-MV tandem accelerator has been installed on large helical device （LHD）. Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of up to 3 T. By using the HIBP, the transition of potential profiles from electron-root to ion^root is observed in core plasmas during ramp-up of the electron density. Potential fluctuations are also measured electron cyclotron current drive （ECCD）. Two kind of characteristic fluctuations are observed. One is a reversed-shear-induced Alfv^n eigenmode （RSAE）, whose frequency varies during the evolution of the rotational transform profile, and the other is with a constant geodeisc acoustic mode （GAM） frequency.展开更多
A new high repetition rate Nd：YAG Thomson scattering system is developed for the Heliotron J helical device. A main purpose of installing the new system is the temporal evolution measurement of a plasma profile for i...A new high repetition rate Nd：YAG Thomson scattering system is developed for the Heliotron J helical device. A main purpose of installing the new system is the temporal evolution measurement of a plasma profile for improved confinement physics such as the edge transport barrier （H-mode） or the internal transport barrier of the helical plasma. The system has 25 spatial points with -10 mm resolution. Two high repetition Nd：YAG lasers （〉 550 m J@ 50 Hz） realize the measurement of the time evolution of the plasma profile with ~10 ms time intervals. Scattered light is collected by a large concave mirror （D----800 mm, f/2.25） with a solid angle of -100 mstr and transferred to interference filter polychromators by optical fiber bundles in a staircase form. The signal is amplified by newly designed fast preamplifiers with DC and AC output, which reduces the low frequency background noise. The signals are digitized with a multi-event QDC, fast gated integrators. The data acquisition is performed by a VME-based system operated by the CINOS.展开更多
基金supported by the JSPS-CAS Core University Program in the field of "'Plasma and Nuclear Fusion"the Collaboration Program of the Laboratory for Complex Energy Processes. IAE. Kyoto University. the NIFS Collaborative flesearch Program (NIFS10KUHL030. etc.)+1 种基金the NIFS/NINS project of Formation of International Network for Scientific Collaborationsthe Grant-in-Aid for Sci.Research. MEXT
文摘Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A supersonic H2-beam is effectively injected to increase fueling efficiency and generate a peaked density profile. Local fueling with a short-pulsed SMBI can increase the core plasma density and avoid the degradation arising from edge cooling. Second harmonic electron cyclotron current drive （ECCD） experiments were conducted by launching a focused Gaussian beam with a parallel refractive index of -0.05 ≤ Nil 〈 0.6. Results show that the electron cyclotron （EC） driven current is determined not only by Nil but also by local magnetic field （B） structure where the EC power is deposited. Detailed analysis of the observed NI and B dependences is in progress with a ray-tracing simulation using the TRAVIS code. Fast ion velocity distribution was investigated using fast protons generated by ion cyclotron resonant frequency （ICRF） minority heating. For the standard configuration in Heliotron J, charge ex- change neutral particle analysis （CX-NPA） measurements show higher effective temperature of fast minority protons in the on-axis resonance case compared to that in the HFS （high field side） off-axis resonance case. However, the increase in bulk ion temperature in the HFS resonance case is larger than that in the on-axis resonance.
基金MEXT Japan under Grant-in-Aid for Young Scientists (Nos.16760674,18760640)the JSPS-CAS Core-University program in the field of Plasma and Nuclear FusionNIFS/NINS under the project of Formation of International Network for Scientific Collaborations and NIFS07ULBB505
文摘A heavy ion beam probe （HIBP） using a 3-MV tandem accelerator has been installed on large helical device （LHD）. Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of up to 3 T. By using the HIBP, the transition of potential profiles from electron-root to ion^root is observed in core plasmas during ramp-up of the electron density. Potential fluctuations are also measured electron cyclotron current drive （ECCD）. Two kind of characteristic fluctuations are observed. One is a reversed-shear-induced Alfv^n eigenmode （RSAE）, whose frequency varies during the evolution of the rotational transform profile, and the other is with a constant geodeisc acoustic mode （GAM） frequency.
基金supported by the Collaboration Program of the Laboratory for Complex Energy Processes,IAE,Kyoto Universitythe NIFS Collaborative Research Program (NIFS10KUHL030,NIFS09KUHL028,NIFS10KUHL033)
文摘A new high repetition rate Nd：YAG Thomson scattering system is developed for the Heliotron J helical device. A main purpose of installing the new system is the temporal evolution measurement of a plasma profile for improved confinement physics such as the edge transport barrier （H-mode） or the internal transport barrier of the helical plasma. The system has 25 spatial points with -10 mm resolution. Two high repetition Nd：YAG lasers （〉 550 m J@ 50 Hz） realize the measurement of the time evolution of the plasma profile with ~10 ms time intervals. Scattered light is collected by a large concave mirror （D----800 mm, f/2.25） with a solid angle of -100 mstr and transferred to interference filter polychromators by optical fiber bundles in a staircase form. The signal is amplified by newly designed fast preamplifiers with DC and AC output, which reduces the low frequency background noise. The signals are digitized with a multi-event QDC, fast gated integrators. The data acquisition is performed by a VME-based system operated by the CINOS.
