During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. ...During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors： electroh cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.展开更多
In order to improve the utilization rate of foam,an arc jet nozzle was designed for precise dust control.Through theoretical analysis,the different demands of foam were compared amongst arc jets,flat jets and full con...In order to improve the utilization rate of foam,an arc jet nozzle was designed for precise dust control.Through theoretical analysis,the different demands of foam were compared amongst arc jets,flat jets and full cone jets when the dust source was covered identically by foam.It is proved that foam consumption was least when an arc jet was used.Foam production capability of an arc jet nozzle under different conditions was investigated through experiments.The results show that with the gas liquid ratio(GLR)increasing,the spray state of an arc jet nozzle presents successively water jet,foam jet and mist.Under a reasonable working condition range of foam production and a fixed GLR,foam production quantity increases at first,and then decreases with the increase of liquid supply quantity.When the inner diameter of the nozzle is 14 mm,the best GLR is 30 and the optimum liquid supply quantity is0.375 m^3/h.The results of field experiments show that the total dust and respirable dust suppression efficiency of arc jet nozzles is 85.8%and 82.6%respectively,which are 1.39 and 1.37 times higher than the full cone nozzles and 1.20 and 1.19 times higher than the fiat nozzles.展开更多
Dear Editor,Pancreatic cancer is a devastating disease ranked as the 4th leading cause of cancer-related deaths in the United States,and its incidence rate is increasing according to the latest statistics.The overall ...Dear Editor,Pancreatic cancer is a devastating disease ranked as the 4th leading cause of cancer-related deaths in the United States,and its incidence rate is increasing according to the latest statistics.The overall survival rates for patients with pan-creatic cancer have not significantly improved over the past thirty years(Siegel et al.,2012;Simard et al.,2012).One of the reasons for the high mortality rates is the high resistance of pancreatic cancer to chemotherapy and radiation.Most patients are diagnosed at late stages of the disease.Approximately 15%-20%of patients diagnosed with pan-creatic cancer are eligible for surgical resection,and 85%of these patients eventually experience relapse and ultimately cancer-related death(Siegel et al.,2012).In recent years,increasing evidence indicates that the fibro-inflammatory stroma is a source of cellular and molecular components contributing to tumor progression and metastasis(Feig et al.,2012;Waghray et al.,2013).Importantly,increased levels of stroma are positively related to a poor prognosis(Erkan et al.,2008).Despite the broader understanding of pancre-atic cancer biology,gemcitabine,a chemotherapeutic approved for pancreatic cancer treatment approximately twenty years ago,still remains the standard of care(Burris et al.,1997).Thus,the development of novel treatment strategies for this devastating disease is urgently needed.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10675124,10775041 and 10775045)
文摘During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors： electroh cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.
基金supported by the National Natural Science Foundation of China(No.51474216)
文摘In order to improve the utilization rate of foam,an arc jet nozzle was designed for precise dust control.Through theoretical analysis,the different demands of foam were compared amongst arc jets,flat jets and full cone jets when the dust source was covered identically by foam.It is proved that foam consumption was least when an arc jet was used.Foam production capability of an arc jet nozzle under different conditions was investigated through experiments.The results show that with the gas liquid ratio(GLR)increasing,the spray state of an arc jet nozzle presents successively water jet,foam jet and mist.Under a reasonable working condition range of foam production and a fixed GLR,foam production quantity increases at first,and then decreases with the increase of liquid supply quantity.When the inner diameter of the nozzle is 14 mm,the best GLR is 30 and the optimum liquid supply quantity is0.375 m^3/h.The results of field experiments show that the total dust and respirable dust suppression efficiency of arc jet nozzles is 85.8%and 82.6%respectively,which are 1.39 and 1.37 times higher than the full cone nozzles and 1.20 and 1.19 times higher than the fiat nozzles.
文摘Dear Editor,Pancreatic cancer is a devastating disease ranked as the 4th leading cause of cancer-related deaths in the United States,and its incidence rate is increasing according to the latest statistics.The overall survival rates for patients with pan-creatic cancer have not significantly improved over the past thirty years(Siegel et al.,2012;Simard et al.,2012).One of the reasons for the high mortality rates is the high resistance of pancreatic cancer to chemotherapy and radiation.Most patients are diagnosed at late stages of the disease.Approximately 15%-20%of patients diagnosed with pan-creatic cancer are eligible for surgical resection,and 85%of these patients eventually experience relapse and ultimately cancer-related death(Siegel et al.,2012).In recent years,increasing evidence indicates that the fibro-inflammatory stroma is a source of cellular and molecular components contributing to tumor progression and metastasis(Feig et al.,2012;Waghray et al.,2013).Importantly,increased levels of stroma are positively related to a poor prognosis(Erkan et al.,2008).Despite the broader understanding of pancre-atic cancer biology,gemcitabine,a chemotherapeutic approved for pancreatic cancer treatment approximately twenty years ago,still remains the standard of care(Burris et al.,1997).Thus,the development of novel treatment strategies for this devastating disease is urgently needed.
