测厚仪原理(中英对照).ppt

《测厚仪原理(中英对照).ppt》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。

1、TheoryofTransmissionGaugingforThicknessMeasurementofMetals穿透式测厚仪测量原理NExcitedElectronLeavingAtomVacancyisfilledbyanouterorbitalelectronwithemissionofcharacteristicX-raysIncidentPhotonX-rayEmissionX-rayFluorescensGenerationFluorescenceRadiationBasicS

2、tructureofanX-RayTubeThex-raytubeconsistsoftwoparts:TheanodeandthecathodeX射线管由两部分组成：阳极和阴极Duetotheelectricalfield,electronsareemittedfromthecathodeandacceleratedtowardstheanode.Inordertoassistintheemissionofelectrons,afilamentinthecathodeisheated.灯丝被通

3、电加热，产生大量的电子，在极间的高压作用下，释放出来的电子高速从阴极运动到阳极。Theelectronshittheanodeatgreatspeed.该电子高速撞击阳极。Whentheelectronscollidewiththeanodematerial,x-raysareproduced.当电子碰撞阳极靶材，产生X射线。Example:100kV,3mA=>Tubepower300W,6Wradiationpowerand294Wthermallosses.6W辐射功率和294W以热量形

4、式丧失。GeneratingX-raysusinganX-rayTubeX射线管产生的X射线BasicStructureofanX-RayTubeTheanodemustbecooled.Theefficiencyofanx-raytubeisaround1-2%.阳极必须具备冷却，只有大约1-2%转化成X射线。（1）X射线的穿透力（能量）取决于管电压。（2）在管电压一定时，X射线的强度取决于管电流，管电流通过灯丝电流调节。（3）管电压和管电流都必须稳定，才能确保检测的准确性。X-raycont

5、rolunitX-rayDRIVERCHASSISX-raySOURCEGlasstubes玻璃管Metalceramictubes金属陶瓷管Advantages优点Economical经济AdvantagesSmallconstructionRobustLongerlifeScreeningoftheradiationbymeansofthex-raytubehousing(Radiationprotection)DisadvantagesLargeconstructionGlasstubec

6、aneasilybebrokenDisadvantagesX-RAYTUBEX-raytubeBasicPrinciples基本原理Trans-missionDetectorSource射线源Metal-Thickness,t（物体-厚度t)穿透射线探头MeasurementofThickness厚度测量MetalBlocksGamma/X-rays物体伽玛/X射线Detector探头Source射线源Steel-Thickness,t（钢-厚度，t）I0=FullIntensityI0=总强度

7、I=IntensityI=强度I=I0e-t/qMeasurementOfThickness厚度测量值Meanfreepath,主自由通道q=f(keV,chemistry)化学成份ThreeWaystouseRadiationforMeasurement射线在测量领域应用的三种主要方式Threemodesofmeasurementmaybeusedaccordingtotheapplication按应用方式可分为三种方式Transmissionmode,usedfordirectmeasur

8、ementofstripthickness穿透式，用于穿透板带测量物体厚度Fluorescencemode,usedtomeasurethicknessofmetalliccoatings莹光反射式，用于测量金属涂层厚度Backscattermode,usedtomeasurethicknessofpaintcoatings反向散射式，用于测量漆层厚度GenerationofX-rays&Gamma-raysX射线和伽玛射线的产生NaturalDecayofIsotope:Am241&Cs13