简介：一种新型激光器以1．4613113的X射线短波长发射出相干脉冲——在能源方面，这就是干电子伏系统。德国电子加速器公司自由电子激光科学中心的NinaRohringer与其它研究人员在报道中称已发明了利用粒子数反转增益的高能激光器，

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简介：Twotransmissioncurvedcrystalspectrometersaredesignedtomeasurethehardx-rayemissioninthelaserfusionexperimentofComptonradiographyofimplosiontargetonShenGuang-IIIlaserfacilityinChina.Cylindricallycurvedα-quartz(10–11)crystalswithcurvatureradiiof150and300mmareusedtocoverspectralrangesof10–56and17–100keV,respectively.Thedistancebetweenthecrystalandthex-raysourcecanbechangedoverabroaddistancefrom200to1500mm.Theopticaldesign,includingtheintegralreflectivityofthecurvedcrystal,thesensitivity,andthespectralresolutionofthespectrometers,isdiscussed.WealsoprovidemechanicdesigndetailsandexperimentalresultsusingaMoanodex-raysource.High-qualityspectrawereobtained.Weconfirmedthatthespectralresolutioncanbeimprovedbyincreasingtheworkingdistance,whichisthedistancebetweentherecordingmediumandtheRowlandcircle.

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简介：利用数值方法计算了磁绝缘线振荡器（MILO）主慢波结构谐振腔和扼流腔的谐振频率和场分布，得出慢波结构谐振腔谐振频率的一些变化规律：随着叶片内半径的增大、叶片外半径的减小、叶片周期的减小以及叶片间距的减小，谐振腔TM01模式截止频率升高；而阴极半径的变化对截止频率几乎无影响。当主慢波结构腔内半径为4．6cm，扼流腔内半径为4．2cm，阴极半径为3cm时，MILO工作在3．“4．4GHz频率范围，扼流片可以阻止微波功率向脉冲功率源泄漏，这有利于提高器件微波输出的效率;

简介：ThedetailedmicrostructuresofNi80Fe20/Fe50Mn50superlatticeshavebeencharacterizedusingbothx-raydiffractiontechniquesandtransmissionelectronmicroscopy.Theobrivouslayeredstructure,typicalcolumnstructureandtwinswhichexistinNi80Fe20/Fe50Mn50superlatticeswereobservedthroughperformingtransmissionmicroscopy.Bycombiningthetechniqueoflowanglex-rayreflectivity(specularandoff-specularscans)withtheanomalousscatteringeffectandhigh-anglex-raydiffraction(usingconventionalx-ray),wequantitativelyanalysedthemicrostructuralvariationasafunctionofannealingtemperature.Itisfoundthatthelateralcorrelationlength,the(111)peakintensityofthesuperlatticesandtheaveragemultilayercoherencelengthallincreasewithariseinannealingtemperatureannealingcandecreasetherootmean-squareroughnessattheinterfacesofNi80Fe20/Fe50Mn50superlattices.theobtainedmicrostructuralknowledgewillbehelpfulinunderstandingthemagneticpropertiesoftheni80Fe20/Fe50Mn50exchangebiassystem.

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简介：Wereportthatβ’-Gd2(MoO4)3crystalshavebeengrownbytheCzochralski(CZ)method.Westudiedthegrowthconditionsfoβ’-Gd2(MoO4)3crystal.Acompatisonbetweentheresistance-heatedmethodandradiofrequencyinduction-heatedmethodisdescribed.Also,theinsituobservationofthedomainstructurebythemicroscopeandbysynchrotronradiationX-raytopographyundertheconditionsofDCpolarizationvoltageandtempertaturechangewerecarriedout.Experimentsshowedthatmultidomainstructureincludingferroelectricandferroelasticdomainsoccurredinβ’-Gd2(MoO4)3cystal.Usuallyferroeletiricdomainsappearedintheas-growncrystalandferroelasticdomainsappearedinthepolishedthinnerpiece.BothferroelectricandferroelasticdomainsdisappearedwhenthetemperatureofthecrystalpiecewashigherthantheCurietempperatureTcandtheycouldbereproducedwhenthetemperatureofthecrystalpiecewasloweredbelowTC.WhenaDCpolarizationvoltagerangingfrom150to500Vwasappliedonac-axisβ’-Gd2(MoO4)3piecehavingathicknessof0.5mm,themultidomainwouldgraduallytransformtoasingledomain.Thisresualmeansthatitispossibletomakeaperiodicallypoledβ’-Gd2(MoO4)3crystal.2001ElsevierScienceB.V.Allrightsreserved.

简介：Si-richsiliconnitridefilmsarepreparedbyplasma-enhancedchemicalvapordepositionmethod,followedbythermalannealingtoformtheSinanocrystals(Si-NCs)embeddedinSiNxfloatinggateMOSstructures.Thecapacitance–voltage(C–V),current–voltage(I–V),andadmittance–voltage(G–V)measurementsareusedtoinvestigatethechargingcharacteristics.Itisfoundthatthemaximumflatbandvoltageshift(△VFB)duetofullchargedholes(～6.2V)ismuchlargerthanthatduetofullchargedelectrons(～1V).ThechargingdisplacementcurrentpeaksofelectronsandholescanbealsoobservedbytheI–Vmeasurements,respectively.FromtheG–VmeasurementswefindthattheholeinjectionisinfluencedbytheoxideholetrapswhicharelocatedneartheSiO2/Si-substrateinterface.CombiningtheresultsofC–VandG–Vmeasurements,wefindthattheholechargingoftheSi-NCsoccursviaatwo-steptunnelingmechanism.TheevolutionofG–VpeakoriginatedfromoxidetrapsexhibitstheprocessofholeinjectionintothesedefectsandtransferringtotheSi-NCs.

简介：Ceriumoxidenanoparticlescoatedbysodiumbis(2-ethylexyl)sulphosuccinate(AOT)werepreparedbyusingamicroemulsionmethod.Transmissionelectronmicroscopyrevealedanaverageparticlesiaeof2-3nm.X-raydiffractionshowedthattheceriumoxidenanoparticlesretaintheCeF2-typecubicstructureslikethebulkcrystal.Theintermediatevalenceofformallytetravalentcompoundshadbeendetectedbyx-ray-absorptionnear-edgestructetravalentcompoundshadbeendetectedbyx-ray-absorptionnear-degestructure(XANES)spectraofCeLIIIabsorptioninbulkCeO2andtheceriumoxidenanoparticles.Twowellresovedwhitelinescanbeassignedtotheelectronconfigurationsof4f^0Land4f^1L,respectively,whereLdenotesaligandhole.Atthesametime,theceriumoxidenanoparticlesalsoshowedthestructuralfeatresoftrivalentcompounds,incomparisontothetrivalentCe(NO3)3·6H2O.FuorLorentzianfunctionsandtwoarctanfunctionswereusedtofitthenormalizedXANESspectra.Theextendedx-ray-absorptionfine-structure(EXAFS)techniquewasusedtoprobethelocalatomicstructuresaroundtheabsorberCe.ThemultielectrornexcitationeffectontheEXAFSspectrawaseliminated.Acor-shellmodelwasusedtodeducethenear-neighbourstructuralparametersaroundcerium.BulkCeO2witheightoxygenatomslocatedat2.343AwasusedasthereferencesampletoextractthebackscatteringamplitudeandphaseshiftoftheCe-Obond.OnehalfoftheatomelocateatthecorepartwiththeCeF2-typecubicstructures(eightoxyensat2.343AaroundCe),theotherhalfoftheatomsareamorphousphaselocatedintheshellpart(surfaceofthenanoparticles)withapproximatelyCe2O3structuralfeatures(averageedsevenoxygensat2.50AaroundCe).

简介：基于传输线变压器原理,设计了一种适用于超宽谱脉冲功率合成的结构。该结构采用二级合成方式,在功率合成的同时实现向高特性阻抗超宽带天线匹配馈电。用4路超宽谱脉冲源进行了功率合成实验,每路脉冲电压1.7kV,前沿200ps,4路同步最大延迟20ps,合成脉冲馈入特性阻抗为200Ω的超宽带天线进行辐射。测量结果表明,采用该功率合成结构的天线辐射场强比单路馈电提高1倍,在20kHz重复频率下工作稳定。实验验证了利用传输线变压器原理进行超宽谱电磁脉冲功率合成的可行性和高效性。

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简介：本文首次采用高温高压固相反应法合成类钙钛矿化合物Ba1－xLaxTiO3（x＝0．0，0．1，0．2，0．3，0．4，0．5）。XRD谱的测量结果表明，在压力为2．8GPa，温度为850℃下，稀土La在BaTiO3中的替代导致结构从立方到四方到正交的结构转变，因此，Ba1－xLaxTiO3体系体现结构转变规律和丰富的物相结构。

简介：Tonguesquamouscellcarcinoma(ToSCC)isthemostcommontypeofheadandnecksquamouscellcarcinomaandisthesixthleadingcauseofcancerdeathsworldwide[1].Inclinicaloncology,radiationtherapyisastandardtreatmentusedfortumors.Numerousstudieshaveshownthatconventionalradiotherapyusedincancertreatmentmayincreasetheriskofmetastasisofmalignanttumorcells[2–4].Toimprovepatientsurvival,thepotentialformetastasisoftumorsinresponsetoradiationneedstobeaddressed.

简介：若无限长均匀带电直导线（线电荷）与接地平板系统的电场是二维静电场,当求解区域可视为为多边形时,则可应用S-C映射法和电像法为统一模型,求解出线电荷在求解区域所激发的电势。

简介：Self-emissionx-rayshadowgraphyprovidesamethodtomeasuretheablation-fronttrajectoryandlow-modenonuniformityofatargetimplodedbydirectlyilluminatingafusioncapsulewithlaserbeams.Thetechniqueusestime-resolvedimagesofsoftx-rays(>1keV)emittedfromthecoronalplasmaofthetargetimagedontoanx-rayframingcameratodeterminethepositionoftheablationfront.Methodsusedtoaccuratelymeasuretheablation-frontradius(δR=±1.15μm),image-to-imagetiming(δ(t)=±2.5ps)andabsolutetiming(δt=±10ps)arepresented.Angularaveragingoftheimagesprovidesanaverageradiusmeasurementofδ(Rav)=±0.15μmandanerrorinvelocityofδV/V=±3%.ThistechniquewasappliedontheOmegaLaserFacility[Boehlyetal.,Opt.Commun.133,495(1997)]andtheNationalIgnitionFacility[CampbellandHogan,PlasmaPhys.Control.Fusion41,B39(1999)].

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简介：不确定度是评估测量结果准确性的重要参数。文中在测量刚体转动惯量的新方法＂相对测量法＂的基础上,给出其不确定度计算公式。新方法通过数学变换,省去了对上悬盘r及上下悬盘距离H的测量,可有效地减小误差。结果表明,公式改进后的计算结果较传统法相对误差降低0.84%,并且随着转角θ的增加,相对误差也随之增大,实验结果与理论分析一致。

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