Exploring solid propellants for electric thrusters can simplify the propellant storage and supply units in propulsion systems.In this study,polytetrafluoroethylene(PTFE),commonly used as a propellant in pulsed plasma ...Exploring solid propellants for electric thrusters can simplify the propellant storage and supply units in propulsion systems.In this study,polytetrafluoroethylene(PTFE),commonly used as a propellant in pulsed plasma thrusters,was embedded in the discharge chamber of a radio frequency ion thruster(RIT-4)to investigate the performance of an ablation-type RIT.Experimental results indicate that PTFE can decompose and ionize stably under plasma ablation within the discharge chamber,producing-C-F-and F-ion clusters that form a stable plasma.By adjusting the length of the PTFE propellant,it was observed that its decomposition rate influences the ion beam current of the thruster.Compared with xenon,PTFE generates an ion plume with a larger divergence angle,ranging from 16.05°to 22.74°at an ion beam current of 25 mA,with a floating potential distribution of 8‒56 V.Assuming that the proportion of neutral gas in the vacuum chamber matches the ion species ratio in the ion plume,thrust,specific impulse and efficiency parameters were calculated for the RIT-4 with embedded PTFE.Under 50 W RF power,the thrust was approximately 1.02 mN,the specific impulse was around 1236 s and the power-to-thrust ratio was approximately 93.14 W/mN.All results indicate that PTFE is a viable propellant for RIT,but the key is to control the rate of decomposition.展开更多
In order to study the stability and prevention plan of a soil landslide in Caidian District, Wuhan, the basic characteristics of the landslide, such as scale, shape, material composition and deformation, were identifi...In order to study the stability and prevention plan of a soil landslide in Caidian District, Wuhan, the basic characteristics of the landslide, such as scale, shape, material composition and deformation, were identified by means of ground investigation, engineering geological mapping and engineering exploration. The recommended values of physical and mechanical parameters of each layer of rock and soil were given by means of laboratory tests, engineering analogy and inversion analysis. The stability of the landslide was analyzed by means of transfer coefficient method. The development trend and harmfulness were predicted in combination with the basic characteristics of the landslide, and scientific prevention suggestions were also given.展开更多
基金supported by the National Key R&D Program of China(No.2021YFC2202800)the Youth Innovation Promotion Association CAS(No.2023022)Institute of Mechanics Outstanding Young Talent Training Program(No.E1Z1030201).
文摘Exploring solid propellants for electric thrusters can simplify the propellant storage and supply units in propulsion systems.In this study,polytetrafluoroethylene(PTFE),commonly used as a propellant in pulsed plasma thrusters,was embedded in the discharge chamber of a radio frequency ion thruster(RIT-4)to investigate the performance of an ablation-type RIT.Experimental results indicate that PTFE can decompose and ionize stably under plasma ablation within the discharge chamber,producing-C-F-and F-ion clusters that form a stable plasma.By adjusting the length of the PTFE propellant,it was observed that its decomposition rate influences the ion beam current of the thruster.Compared with xenon,PTFE generates an ion plume with a larger divergence angle,ranging from 16.05°to 22.74°at an ion beam current of 25 mA,with a floating potential distribution of 8‒56 V.Assuming that the proportion of neutral gas in the vacuum chamber matches the ion species ratio in the ion plume,thrust,specific impulse and efficiency parameters were calculated for the RIT-4 with embedded PTFE.Under 50 W RF power,the thrust was approximately 1.02 mN,the specific impulse was around 1236 s and the power-to-thrust ratio was approximately 93.14 W/mN.All results indicate that PTFE is a viable propellant for RIT,but the key is to control the rate of decomposition.
文摘In order to study the stability and prevention plan of a soil landslide in Caidian District, Wuhan, the basic characteristics of the landslide, such as scale, shape, material composition and deformation, were identified by means of ground investigation, engineering geological mapping and engineering exploration. The recommended values of physical and mechanical parameters of each layer of rock and soil were given by means of laboratory tests, engineering analogy and inversion analysis. The stability of the landslide was analyzed by means of transfer coefficient method. The development trend and harmfulness were predicted in combination with the basic characteristics of the landslide, and scientific prevention suggestions were also given.
