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
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
针对稠油热采存在油汽比低、能耗大、CO_(2)排放高以及稠油冷采采出液难处理等问题,采用自制的降黏驱油剂ODA1配制驱替液,对其进行了静态降黏评价、性能分析以及特稠油冷采物理模拟实验研究。结果表明:提高驱替液中ODA1的质量分数和矿化...针对稠油热采存在油汽比低、能耗大、CO_(2)排放高以及稠油冷采采出液难处理等问题,采用自制的降黏驱油剂ODA1配制驱替液,对其进行了静态降黏评价、性能分析以及特稠油冷采物理模拟实验研究。结果表明:提高驱替液中ODA1的质量分数和矿化度,均能有效降低稠油黏度;当驱替液中ODA1质量分数为2%、矿化度为100 g/L时,特稠油与驱替液以质量比为0.5混合后的降黏率达到了70.62%;特稠油在驱替液表面自发扩散,油水自动分相,完全不乳化。在渗透率约为1 000×10^(-3)μm^(2)、地层温度为40℃、特稠油黏度为11 600 m Pa·s条件下进行模拟驱油实验,驱替液驱的采出程度较模拟地层水驱采出程度提高了6.31百分点;水驱后驱替液依次进行转驱、第1次闷井和第2次闷井,采出程度分别提高了7.48、11.70和7.83百分点,合计较水驱提高了27.02百分点,采出稠油在40℃条件下的黏度降至3 553 m Pa·s,降黏率达61.37%,驱替液具有边驱油边降黏的特点。同时在冷采过程中无碳排放,采出水无污染,可循环利用。研究成果为特稠油绿色冷采提供了一种新的技术思路。展开更多
海平面下降和海底温度上升可以引起海底水合物分解,进而导致天然气水合物稳定带底界处沉积物孔隙形成超压,一旦超压积聚突破地层有效应力,就会在海底产生甲烷渗漏。本文通过建立与此相关的稳定带底界变化的数值模型,以分析南海北部东沙...海平面下降和海底温度上升可以引起海底水合物分解,进而导致天然气水合物稳定带底界处沉积物孔隙形成超压,一旦超压积聚突破地层有效应力,就会在海底产生甲烷渗漏。本文通过建立与此相关的稳定带底界变化的数值模型,以分析南海北部东沙海域GMGS2-16水合物钻探站位25 ka BP以来稳定带底界的动态变化。结果显示,在海平面上升的大背景下,海底温度的波动是稳定带底界动态变化的主要因素,主导了水合物生成和分解的周期性变化。底水温度升高导致稳定带底界上移,水合物分解,造成大量甲烷气体的释放,然而这种响应呈现一定的滞后,大约滞后1~3 ka。此外,水合物钻探获取的相应层位沉积物中出现了Mo元素富集的现象,表明稳定带底界上升及水合物分解形成的气体超压可以形成海底冷泉活动。因此,天然气水合物分解可能是冷泉渗漏活动的驱动机制。展开更多
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.
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.
文摘针对稠油热采存在油汽比低、能耗大、CO_(2)排放高以及稠油冷采采出液难处理等问题,采用自制的降黏驱油剂ODA1配制驱替液,对其进行了静态降黏评价、性能分析以及特稠油冷采物理模拟实验研究。结果表明:提高驱替液中ODA1的质量分数和矿化度,均能有效降低稠油黏度;当驱替液中ODA1质量分数为2%、矿化度为100 g/L时,特稠油与驱替液以质量比为0.5混合后的降黏率达到了70.62%;特稠油在驱替液表面自发扩散,油水自动分相,完全不乳化。在渗透率约为1 000×10^(-3)μm^(2)、地层温度为40℃、特稠油黏度为11 600 m Pa·s条件下进行模拟驱油实验,驱替液驱的采出程度较模拟地层水驱采出程度提高了6.31百分点;水驱后驱替液依次进行转驱、第1次闷井和第2次闷井,采出程度分别提高了7.48、11.70和7.83百分点,合计较水驱提高了27.02百分点,采出稠油在40℃条件下的黏度降至3 553 m Pa·s,降黏率达61.37%,驱替液具有边驱油边降黏的特点。同时在冷采过程中无碳排放,采出水无污染,可循环利用。研究成果为特稠油绿色冷采提供了一种新的技术思路。
文摘海平面下降和海底温度上升可以引起海底水合物分解,进而导致天然气水合物稳定带底界处沉积物孔隙形成超压,一旦超压积聚突破地层有效应力,就会在海底产生甲烷渗漏。本文通过建立与此相关的稳定带底界变化的数值模型,以分析南海北部东沙海域GMGS2-16水合物钻探站位25 ka BP以来稳定带底界的动态变化。结果显示,在海平面上升的大背景下,海底温度的波动是稳定带底界动态变化的主要因素,主导了水合物生成和分解的周期性变化。底水温度升高导致稳定带底界上移,水合物分解,造成大量甲烷气体的释放,然而这种响应呈现一定的滞后,大约滞后1~3 ka。此外,水合物钻探获取的相应层位沉积物中出现了Mo元素富集的现象,表明稳定带底界上升及水合物分解形成的气体超压可以形成海底冷泉活动。因此,天然气水合物分解可能是冷泉渗漏活动的驱动机制。
