Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an incre...Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an increment of ~100 eV in plasma electron temperature has been observed in most of the discharges compared to discharges without Li coating, and the shot reproducibility is considerably improved. Detailed studies of impurity behaviour and hydrogen recycling are made in the Li coated discharges by observing spectral lines of hydrogen, carbon, and oxygen in the visible region using optical fiber, an interference filter, and PMT based systems. A large reduction in O I signal （up to ~40% to 50%） and a 20% to 30% decrease of Ha signal indicate significant reduction of wall recycling. Furthermore, VUV emissions from O V and Fe XV monitored by a grazing incidence monochromator also show the reduction. Lower Fe XV emission indicates the declined impurity penetration to the core plasma in the Li coated discharges. Significant increase of the particle and energy confinement times and the reduction of Zeff of the plasma certainly indicate the improved plasma parameters in the Aditya tokamak after lithium wall conditioning.展开更多
Flooding phenomenon limits the stability and the flow of a liquid film falling along the walls of a channel in which a gas in flowing upwards.As knows,the entrainment effect can completely prevent the liquid to fall f...Flooding phenomenon limits the stability and the flow of a liquid film falling along the walls of a channel in which a gas in flowing upwards.As knows,the entrainment effect can completely prevent the liquid to fall from its natural flow.The resesent work proposes a new mechanistic model for the prediction of the onset of floodung in vertical and inclined pipes in the presence of obstructions,as well as taking into account the viscosity effect.The good performance of the model in the different geometrical conditions and for variable viscosities of the liquid component assesses the validity of the hypothesis that the instability of a wavelike disturbance limits the countercurrent flow in a channel.展开更多
文摘Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an increment of ~100 eV in plasma electron temperature has been observed in most of the discharges compared to discharges without Li coating, and the shot reproducibility is considerably improved. Detailed studies of impurity behaviour and hydrogen recycling are made in the Li coated discharges by observing spectral lines of hydrogen, carbon, and oxygen in the visible region using optical fiber, an interference filter, and PMT based systems. A large reduction in O I signal （up to ~40% to 50%） and a 20% to 30% decrease of Ha signal indicate significant reduction of wall recycling. Furthermore, VUV emissions from O V and Fe XV monitored by a grazing incidence monochromator also show the reduction. Lower Fe XV emission indicates the declined impurity penetration to the core plasma in the Li coated discharges. Significant increase of the particle and energy confinement times and the reduction of Zeff of the plasma certainly indicate the improved plasma parameters in the Aditya tokamak after lithium wall conditioning.
文摘Flooding phenomenon limits the stability and the flow of a liquid film falling along the walls of a channel in which a gas in flowing upwards.As knows,the entrainment effect can completely prevent the liquid to fall from its natural flow.The resesent work proposes a new mechanistic model for the prediction of the onset of floodung in vertical and inclined pipes in the presence of obstructions,as well as taking into account the viscosity effect.The good performance of the model in the different geometrical conditions and for variable viscosities of the liquid component assesses the validity of the hypothesis that the instability of a wavelike disturbance limits the countercurrent flow in a channel.
