共查询到20条相似文献,搜索用时 62 毫秒
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日蒸发率是评价高真空多层绝热杜瓦保冷性能最重要的技术参数。该文对日蒸发率的影响因素进行了总结,重点介绍了储存压力和环境温度对日蒸发率的影响。以充满率为90%的210L小型杜瓦为例,测试了日蒸发率的变化规律。结果表明,杜瓦的日蒸发率与储存压力成正比,同时日蒸发率的波动随着储存压力的升高而增大,且环境温度对日蒸发率的影响出现延迟。 相似文献
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1IntroductionTheradiativepropertiesofatomicsystemsinasquezedvacuumhavebenthesubjectofintenseinvestigationoverthepastdecade.As... 相似文献
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A study is made of the steady-state populations of a three-level ladder atom in a squeezed vacuum, driven by a superposition of a monochromatic laser wave with incoherent population pumping. Using the density matrix equations for the system, the steady-state populations are calculated numerically and shown graphically as functions of two-photon detuning for various cases of the squeezed vacuum and different incoherent pump rates. It is shown that the incoherent population pumping tends to greatly decrease the two-photon absorption from the squeezed vacuum. 相似文献
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The number of least degrees of freedom required for a polarization controller to transform any state of polarization to any other output covering the entire Poincaré sphere 下载免费PDF全文
Using two typical types of polarization controller, this paper
analyses theoretically and experimentally the fact that it is
necessary to adjust at least three instead of two waveplates in
order to transform any state of polarization to any other output
covering the entire Poincar\'{e} sphere. The experimental results
are exactly in accordance with the theory discussed in this paper.
It has corrected the conventional and inaccurate point of view that
two waveplates of a polarization controller are adequate to complete
the transformation of state of polarization. 相似文献
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Electron-positron pair production rate created from vacuum in the presence of an elliptically polarized laser field is investigated.By applying the technique of two level transition amplitude,a routine for obtaining pair production rate is presented,and approximate analytical expressions are given both for the low frequency strong field regime and the high frequency weak field regime.We found that for an elliptically polarized field,the electron-positron pair production rate decrease when the elliptic eccentricity increase in the high frequency weak field regime,however,in the low frequency strong field regime,there is almost the same electron-positron pair production rate as in the constant electric field case. 相似文献
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We have revealed an anomalous dependence of the lasing characteristics of an ethanol solution of rhodamine 6G on the spectral composition of the exciting radiation due to the structure of the excited singlet-singlet absorption spectra and the absorption spectra of short-lived photoexcitation products. Elucidation of the influence of the indicated characteristics makes it possible to select optimum pumping spectra and increase the efficiency and stability of the spectral characteristics of dye-laser systems operating in the microsecond and nanosecond wavelength ranges. 相似文献
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Polarization mode dispersion (PMD) is the ultimate limitation to high bit-rate fibre communication system. The stability of PMD is very important to its measurement and compensation. This paper puts forward a method to measure the stability of PMD by measuring the stability of the state of polarization (SOP) and introduces the conception of time evolution vector (TEV) of SOP. We observe the fact that the regularity of the principal state of polarization changing with time is the same as other SOPs‘‘, if we neglect the dependence of TEV on wavelength. We also measure the SOP‘‘s stability of some fibres with different lengths, and obtain results of PMD changing with time. 相似文献