用溶剂热方法制备Co_xFe_(3-x)O_4(0≤x≤1)亚微米球,可看作不同比例Fe_3O_4和CoFe2O4的混合物。实验发现:当原料中钴铁原子比为1∶1、1∶2、1∶4和0时,反应得到的球分别为CoFe_2O_4、Co_(0.9)Fe_(2.1)O_4、Co_(0.73)Fe_(2.27)O_4和Fe_3...用溶剂热方法制备Co_xFe_(3-x)O_4(0≤x≤1)亚微米球,可看作不同比例Fe_3O_4和CoFe2O4的混合物。实验发现:当原料中钴铁原子比为1∶1、1∶2、1∶4和0时,反应得到的球分别为CoFe_2O_4、Co_(0.9)Fe_(2.1)O_4、Co_(0.73)Fe_(2.27)O_4和Fe_3O_4。Fe_3O_4与石蜡混合物(质量分数75wt%)厚度为5.5 mm时,反射率最低为-38 d B,对应频率为4 GHz;Co_(0.9)Fe_(2.1)O_4与石蜡混合物在3~14 GHz频率范围内介电损耗大于磁损耗,计算出来的反射率分贝值(-41.1 d B,12.08GHz,2 mm)低于相关报道。比较四种成分的钴铁氧体球可以看出:当x值不同时,由于成分Fe_3O_4和CoFe_2O_4的自然共振频率不同,引起磁性能随微波频率发生变化,而且由于二价铁离子被钴离子取代,结晶性也发生改变,进而改变了材料的介电和吸波性能。展开更多
Cooling is very important for the safe operation of an electron cyclotron resonance ion source(ECRIS),especially when the window current density is very high(up to 11 A/mm2).We proposed an innovative cooling method us...Cooling is very important for the safe operation of an electron cyclotron resonance ion source(ECRIS),especially when the window current density is very high(up to 11 A/mm2).We proposed an innovative cooling method using evaporative cooling technology.A demonstration prototype was designed,built and tested.The on-site test results showed that the temperature of the solenoids and permanent magnets maintains well in the normal operational range of 14–18 GHz.A simple computational model was developed to predict the characteristics of the two-phase flow.The predicted temperatures agreed well with the on-site test data within 2 K.We also proposed useful design criteria.The successful operation of the system indicates the potential for broad application of evaporative cooling technology in situations in which the power intensity is very high.展开更多
文摘用溶剂热方法制备Co_xFe_(3-x)O_4(0≤x≤1)亚微米球,可看作不同比例Fe_3O_4和CoFe2O4的混合物。实验发现:当原料中钴铁原子比为1∶1、1∶2、1∶4和0时,反应得到的球分别为CoFe_2O_4、Co_(0.9)Fe_(2.1)O_4、Co_(0.73)Fe_(2.27)O_4和Fe_3O_4。Fe_3O_4与石蜡混合物(质量分数75wt%)厚度为5.5 mm时,反射率最低为-38 d B,对应频率为4 GHz;Co_(0.9)Fe_(2.1)O_4与石蜡混合物在3~14 GHz频率范围内介电损耗大于磁损耗,计算出来的反射率分贝值(-41.1 d B,12.08GHz,2 mm)低于相关报道。比较四种成分的钴铁氧体球可以看出:当x值不同时,由于成分Fe_3O_4和CoFe_2O_4的自然共振频率不同,引起磁性能随微波频率发生变化,而且由于二价铁离子被钴离子取代,结晶性也发生改变,进而改变了材料的介电和吸波性能。
基金supported by the Open Research Project of the Major Science and Technology Infrastructure in the Chinese Academy of Sciences-Application of Evaporative Cooling Technology in the Field of Accelerator
文摘Cooling is very important for the safe operation of an electron cyclotron resonance ion source(ECRIS),especially when the window current density is very high(up to 11 A/mm2).We proposed an innovative cooling method using evaporative cooling technology.A demonstration prototype was designed,built and tested.The on-site test results showed that the temperature of the solenoids and permanent magnets maintains well in the normal operational range of 14–18 GHz.A simple computational model was developed to predict the characteristics of the two-phase flow.The predicted temperatures agreed well with the on-site test data within 2 K.We also proposed useful design criteria.The successful operation of the system indicates the potential for broad application of evaporative cooling technology in situations in which the power intensity is very high.
