This paper investigates the diocotron instability of an infinitely wide relativistic sheet electron beam in conducting wMls propagating through a uniform magnetic field by using the macroscopic cold-fluid model theory...This paper investigates the diocotron instability of an infinitely wide relativistic sheet electron beam in conducting wMls propagating through a uniform magnetic field by using the macroscopic cold-fluid model theory. Assuming low- frequency perturbations with long axial wavelengths, the eigenvalue equation and the dispersion relation are acquired for a sheet electron beam with sharp boundary profile and uniform density. The results presented in this paper has developed the use of the macroscopic cold-fluid model theory by extending the parameter of the electron cyclotron frequency ωc to a wider usage range, which is restricted to be much larger than the plasma frequency ωp in the previous research work. Theoretical analyses and numerical calculations indicate that the transport of the sheet electron beam will be completely stabilized by augmenting the normalized beam thickness to a conductor gap larger than a threshold λb, which is greatly dependent on the parameter ωc/ωp. The larger ωc/ωp is, the smaller λb will be needed. Moreover, the system parameters, including the wave number kx of the perturbations and the relativistic mass factor γb, will also influence the growth rate of diocotron instability obviously.展开更多
The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.T...The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.展开更多
目的研究温度对Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂微渗漏的影响,为临床选择较理想的流体树脂提供参考。方法选取因正畸拔除的成人离体前磨牙60颗,随机分为10组(n=12),根...目的研究温度对Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂微渗漏的影响,为临床选择较理想的流体树脂提供参考。方法选取因正畸拔除的成人离体前磨牙60颗,随机分为10组(n=12),根据是否经过冷热循环老化实验,分为F00A组、Z350A组、SDRA组、TetricA组、ConsticA组,F00B组、Z350B组、SDRB组、TetricB组、ConsticB组,共10组。每颗离体牙咬合面预备成宽2 mm、长4 mm、深2 mm的Ⅰ类洞,分别用所属组别流体树脂充填,A组试件亚甲基蓝染色实验,B组试件先进行5000次冷热循环老化实验后再进行亚甲基蓝染色实验,之后将所有试件牙冠部沿颊舌(腭)方向平行于牙体长轴纵向剖开,体视显微镜下观察各组微渗漏情况,记录数据并分析。结果①F00A组、Z350A组、SDRA组、TetricA组、ConsticA组5组微渗漏的差异并没有统计学意义(P>0.05)。②SDRB组、TetricB组的微渗漏程度大于F00B组、Z350B组,差异具有统计学意义(P<0.05)。③温度对Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂之间的微渗漏程度影响有显著差异(P<0.05)。结论①未经过冷热循环老化实验时,Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂的即刻微渗漏程度无明显差异。②经过冷热循环老化实验后,SDR流体树脂、Tetric^(®)N⁃Flow流体树脂微渗漏程度较高,边缘密合性不佳;Beautifil Flow Plus F00流体树脂、Filtek^(TM)Z350 XT流体树脂微渗漏程度较低,边缘密合性较优。③冷热循环老化实验加重了Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂的微渗漏程度。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 60501019, 10775139, and 60971073)
文摘This paper investigates the diocotron instability of an infinitely wide relativistic sheet electron beam in conducting wMls propagating through a uniform magnetic field by using the macroscopic cold-fluid model theory. Assuming low- frequency perturbations with long axial wavelengths, the eigenvalue equation and the dispersion relation are acquired for a sheet electron beam with sharp boundary profile and uniform density. The results presented in this paper has developed the use of the macroscopic cold-fluid model theory by extending the parameter of the electron cyclotron frequency ωc to a wider usage range, which is restricted to be much larger than the plasma frequency ωp in the previous research work. Theoretical analyses and numerical calculations indicate that the transport of the sheet electron beam will be completely stabilized by augmenting the normalized beam thickness to a conductor gap larger than a threshold λb, which is greatly dependent on the parameter ωc/ωp. The larger ωc/ωp is, the smaller λb will be needed. Moreover, the system parameters, including the wave number kx of the perturbations and the relativistic mass factor γb, will also influence the growth rate of diocotron instability obviously.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60501019,10775139 and 60971073)
文摘The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.
文摘目的研究温度对Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂微渗漏的影响,为临床选择较理想的流体树脂提供参考。方法选取因正畸拔除的成人离体前磨牙60颗,随机分为10组(n=12),根据是否经过冷热循环老化实验,分为F00A组、Z350A组、SDRA组、TetricA组、ConsticA组,F00B组、Z350B组、SDRB组、TetricB组、ConsticB组,共10组。每颗离体牙咬合面预备成宽2 mm、长4 mm、深2 mm的Ⅰ类洞,分别用所属组别流体树脂充填,A组试件亚甲基蓝染色实验,B组试件先进行5000次冷热循环老化实验后再进行亚甲基蓝染色实验,之后将所有试件牙冠部沿颊舌(腭)方向平行于牙体长轴纵向剖开,体视显微镜下观察各组微渗漏情况,记录数据并分析。结果①F00A组、Z350A组、SDRA组、TetricA组、ConsticA组5组微渗漏的差异并没有统计学意义(P>0.05)。②SDRB组、TetricB组的微渗漏程度大于F00B组、Z350B组,差异具有统计学意义(P<0.05)。③温度对Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂之间的微渗漏程度影响有显著差异(P<0.05)。结论①未经过冷热循环老化实验时,Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂的即刻微渗漏程度无明显差异。②经过冷热循环老化实验后,SDR流体树脂、Tetric^(®)N⁃Flow流体树脂微渗漏程度较高,边缘密合性不佳;Beautifil Flow Plus F00流体树脂、Filtek^(TM)Z350 XT流体树脂微渗漏程度较低,边缘密合性较优。③冷热循环老化实验加重了Beautifil Flow Plus F00、Filtek^(TM)Z350 XT、SDR、Tetric^(®)N⁃Flow、Constic这5种流体树脂的微渗漏程度。
