Abstract. Significant experimental advances have been made on HL-2A tokamak along with substantial improvement and development of hardware. The three dimensional spectral structures of the low frequency zonal flow, the geodesic acoustic mode (GAM), and quasi-mode-like low frequency fluctuations have been observed simultaneously for the first time. In addition, the spectral structure of the density fluctuation at GAM frequency is also identified. A spontaneous particle transport barrier has been observed in Ohmic discharges without any external momentum input. The barrier is evidenced by particle perturbation study using modulated SMBI and microwave reflectometry. The non-local transport effect with new features induced by SMBI has been investigated. The e-fishbone instability excited by energetic electrons of non-Maxwellian distribution has been investigated via 10-channel CdTe hard x-ray detector. It is found that the e-fishbone is correlated with the existence of energetic electrons of 30-70 keV. The experiment shows that the suppression of m/n = 2/1 tearing modes can be sustained by ECRH with low modulation frequency of about 10 Hz. Extended confinement improvement is obtained after the mode suppression.
In our previous work, soft magnetic composite (SMC) material was employed to design cores for two kinds of permanent magnet (PM) synchronous motors, namely transverse flux motor and claw pole motor. This paper presents robust design optimization method for the quality control of these PM-SMC motors to improve their industrial applications. Besides traditional theoretical design and analysis, manufacturing condition, tolerance, noise factors and manufacturing costs are investigated in the robust design and optimization models in order to achieve six sigma quality manufacturing for these motors. Thereafter, a PM-SMC transverse flux motor is investigated to illustrate the performance of the proposed method. From the discussion, it can be found that the proposed method can significantly improve the manufacturing quality and reliability of the motor, and reduce the manufacturing cost as well.
Two experiment campaigns were conducted on HL-2A tokamak in 2003 and in 2004 after the first plasma was obtained at the end of 2002. Progresses in many aspects have been made, especially in the divertor discharge and feedback control of plasma configuration. Up to now, the following operation parameters have been achieved: Ip = 320 kA, Bt = 2.2 T and discharge duration T d = 1580 ms. With the feedback control of plasma current and horizontal position, an excellent repeatability of discharge has been achieved. The tokamak has been operated at both limitor configuration and single null (SN) divertor configuration. The HL-2A SN divertor configuration is simulated with the MHD equilibrium code SWEQU. The divertor experiment results were compared with the simulation results obtained with B2. When the divertor configuration is formed, the impurity radiation in main plasma decreases remarkably. The plasma performances are improved significantly after siliconization.
Recent experiment results from the HL-2A tokamak are presented in this paper. Supersonic molecular beam injection (SMBI) with liquid nitrogen temperature propellant is used. Low temperature SMBI can form hydrogen clusters that penetrate into the plasma more deeply and efficiently. Particle diffusion coefficient and convection velocity (D = 0.5–1.5 m2 s−1 and Vconv < 40 m s−1, respectively) are obtained at the plasma periphery using modulated SMBI. Multi-probe measurements reveal the m = 0–1, n = 0 symmetries of directly measured low frequency (7–9 kHz) electric potential and field are simultaneously observed for the first time. Impurity transport is determined with the laser blow-off system and transport code. A disruption predictor has been derived based on MHD activity observations and statistical analysis. Sawtooth characteristics during ECRH are investigated and coupling between m = 1 and m/n = 2/1 modes is studied. Detachment features of HL-2A divertor are numerically and experimentally studied using the code SOLPS5.0 and measured data. The long divertor legs and thin divertor throats in HL-2A pose MHD shaping problems resulting in momentum losses even at low densities and strongly enhanced main chamber losses.
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