In this study,a high specific impulse Hall thruster,HEP-140 MF,having a high discharge voltage,was used to accelerate ions.We aimed to obtain a high specific impulse and an acceleration zone moving downstream toward t...In this study,a high specific impulse Hall thruster,HEP-140 MF,having a high discharge voltage,was used to accelerate ions.We aimed to obtain a high specific impulse and an acceleration zone moving downstream toward the channel exit to reduce wall sputtering erosion of the walls of the discharge channel,hence ensuring an enhanced lifetime.To study the lifetime characteristics of the high specific impulse Hall thruster,a life test was performed on the HEP-140 MF thruster for the first time,and performance parameters,such as thrust,specific impulse,and efficiency,were measured.Changes in the performance parameters and evolutions in the surface profiles of the discharge channel wall were summarized.The reasons contributing to these changes during the life test were analyzed.Moreover,the accelerated life test method was validated on the HEP-140 MF.展开更多
In order to estimate the shelf-life of cow milk sterilized by instant treated with Ultra Heat Temperature(UHT) in a relatively short time,the accelerated shelf-life testing (ASLT) was designed and conducted,selecting ...In order to estimate the shelf-life of cow milk sterilized by instant treated with Ultra Heat Temperature(UHT) in a relatively short time,the accelerated shelf-life testing (ASLT) was designed and conducted,selecting the histological change of the sterilized milk caused by fat droplets creaming as its criteria.The stability index (SI) and the viscosity variation of the sterilized milk were determined at preservation conditions of 20,25,30,35,40 and 45℃,using Turbiscan technology.The result showed that the SI was slightly higher for 25℃ than for 20℃,elevating linearly for temperature from 25℃ to 40℃,and decreased for 40℃ to 45℃.The SI data for 25℃ to 40℃ were fitted well with equation SIt=0.062t-1.382 (R2=0.990).If a ratio SIt/SI25℃ called as accelerated ratio (AR) was defined,the AR values calculated from the equation were 3.6,4.3 and 5.0 for 35,37.5 and 40℃,respectively,which were agreement with the data from ASLT.So,the model could be used for the prediction of the shelf-life of sterilized milk by UHT process.展开更多
基金supported by Space Advance Research program (No. D010509)National Natural Science Foundation of China (No. 51806011)National Defense Pre-Research Foundation of China (No. JSZL2016203C006)。
文摘In this study,a high specific impulse Hall thruster,HEP-140 MF,having a high discharge voltage,was used to accelerate ions.We aimed to obtain a high specific impulse and an acceleration zone moving downstream toward the channel exit to reduce wall sputtering erosion of the walls of the discharge channel,hence ensuring an enhanced lifetime.To study the lifetime characteristics of the high specific impulse Hall thruster,a life test was performed on the HEP-140 MF thruster for the first time,and performance parameters,such as thrust,specific impulse,and efficiency,were measured.Changes in the performance parameters and evolutions in the surface profiles of the discharge channel wall were summarized.The reasons contributing to these changes during the life test were analyzed.Moreover,the accelerated life test method was validated on the HEP-140 MF.
文摘In order to estimate the shelf-life of cow milk sterilized by instant treated with Ultra Heat Temperature(UHT) in a relatively short time,the accelerated shelf-life testing (ASLT) was designed and conducted,selecting the histological change of the sterilized milk caused by fat droplets creaming as its criteria.The stability index (SI) and the viscosity variation of the sterilized milk were determined at preservation conditions of 20,25,30,35,40 and 45℃,using Turbiscan technology.The result showed that the SI was slightly higher for 25℃ than for 20℃,elevating linearly for temperature from 25℃ to 40℃,and decreased for 40℃ to 45℃.The SI data for 25℃ to 40℃ were fitted well with equation SIt=0.062t-1.382 (R2=0.990).If a ratio SIt/SI25℃ called as accelerated ratio (AR) was defined,the AR values calculated from the equation were 3.6,4.3 and 5.0 for 35,37.5 and 40℃,respectively,which were agreement with the data from ASLT.So,the model could be used for the prediction of the shelf-life of sterilized milk by UHT process.
