No abstract available

No abstract available

[en] Impurity transport has been investigated on the HL-1M tokamak under the conditions of the ohmically heated discharge (OHD) and the lower hybrid current drive (LHCD). A small quantity of metallic impurity Al were injected into the plasma using the laser blow-off (LBO) technique. The ionized metallic impurity lines were measured using a vacuum ultra-violet (VUV) spectrometry. Al impurity transports in the plasma under the conditions of the OHD and LHCD were analyzed. The diffusion coefficient (D(r)) and inward convection velocity (V(r)) were obtained using numerical simulation with the impurity transport code (ITC). The simulation results showed that the transport coefficient during the LHCD decreased by fifty per cent compared with that during the OHD. Therefore the impurity-confined characteristics of the LHCD plasma was obviously improved

[en] Impurity transport has been studied in the HL-1 M tokamak under the conditions of ohmic discharge and LHCD. Metallic impurities were injected into the plasma using the laser blow-off technique. The ionized metallic impurity lines were measured using a VUV spectrometer. Simulation analyses of impurity transport were carried out for ohmic discharge and LHCD. Using the numerical simulation with the impurity transport code LBO, the diffusion coefficient D(r) and inward convection velocity υ(r) were obtained. The impurity transport coefficient D(r) during LHCD decreased to nearly half of that during ohmic discharge. The experimental results show that the characteristics of the impurity confinement during LHCD is better than during ohmic discharge

[en] A high speed CCD camera has been used to take photos of H_α line emission during hydrogen-pellet injection in the HL-1M tokamak. The observations are performed in the direction of pellet injection. Photographs with various shapes of the pellet ablation cloud are obtained. They show the track bending and the appearance of striation. Through treatment of the photos the space distribution of light radiation of the cloud, the trajectory and velocity of pellet are given, and the physical mechanism of pellet-plasma interactions is also analyzed. Therefore this work lays the foundation for further measurements of local magnetic field and current profile of plasma with CCD camera under the condition of pellet injection

[en] This paper presents a new model to study the static performances of a GaN metal epitaxial-semiconductor field effect transistor (MESFET) based on the metal–semiconductor interface state of the Schottky junction. The I–V performances of MESFET under different channel lengths and different operating systems (pinch-off or not) have been achieved by our model, which strictly depended on the electrical parameters, such as the drain-gate capacity C _gd, the source–gate capacity C _gs, the transconductance, and the conductance. To determine the accuracy of our model, root-mean-square (RMS) errors were calculated. In the experiment, the experimental data agree with our model. Also, the minimum value of the electrical parameter has been calculated to get the maximum cut-off frequency for the GaN MESFET. (paper)

[en] The author describes plasma radiation loss measurements after thin film coating on the first wall (boronization, siliconization or lithiumization) and during LHCD in the HL-1M tokamak. The results show that radiation loss power is reduced obviously after wall conditioning. The reason why radiation loss is rising or dropping on injection of LHW is analysed. Some useful suggestions are proposed to improve the plasma performance

[en] With the folding target and double-step target, the propagating character of shock wave driven by an inclined-incident (with angle of ∼45 degree) laser was studied on 'Shenguang-II' high-power laser facility. The result indicated that the shock wave in the target still propagates along the vertical direction to the target surface. Also the same result was verified indirectly by another experiment based on the measurement for spatial intensity distribution of x-ray radiated from jet plasmas

[en] The X-ray laser is a useful tool in dense plasma diagnostics because of its short wavelength, high intensity and coherence. A brief description of its applications is given here based on various demonstration experiments, including an introduction to the principle of plasma diagnostics, the fabrication of X-ray lasers, and the results of diagnostic experiments using the Moire deflector and Mach-Zehnder interferometer. (author)

[en] A soft x-ray spectra of double-driven laser-produced Ta plasmas is measured by a time-integrated space-resolved keV crystal spectrometer from 0.45 to 0.75 nm. Some resonant transition of the Ni-like, Co-like and Fe-like ions and some intrashell transition of the Ni-like ions are identified. The experimental results have been processed, the spectroscopic line intensity of the higher ionization stages is obtained. The effect of the double-laser driven time difference on the plasma condition is inferred through the spectroscopic line ratio diagnostics. The results obtained can, at least in part, give a good explanation of the upper lasing level population and the ionization properties of the plasmas