ASTM E296-1970(2015) 2532 Standard Practice for Ionization Gage Application to Space Simulators《空间模拟器电离计应用的标准实施规程》.pdf
《ASTM E296-1970(2015) 2532 Standard Practice for Ionization Gage Application to Space Simulators《空间模拟器电离计应用的标准实施规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM E296-1970(2015) 2532 Standard Practice for Ionization Gage Application to Space Simulators《空间模拟器电离计应用的标准实施规程》.pdf(14页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: E296 70 (Reapproved 2015)Standard Practice forIonization Gage Application to Space Simulators1This standard is issued under the fixed designation E296; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides application criteria, definitions,and supplemental information to assist the user in obtainingmeaning
3、ful vacuum ionization gage measurements below 101N/m2(103torr) in space-simulation facilities. Since a varietyof influences can alter observed vacuum measurements, meansof identifying and assessing potential problem areas receiveconsiderable attention. This practice must be consideredinformational,
4、for it is impossible to specify a means ofapplying the vacuum-measuring equipment to guarantee accu-racy of the observed vacuum measurement. Therefore, theusers judgment is essential so that if a problem area isidentified, suitable steps can be taken to either minimize theeffect, correct the observe
5、d readings as appropriate, or note thepossible error in the observation.1.2 While much of the discussion is concerned with theapplication of hot-cathode ionization gages, no exclusion ismade of cold-cathode designs. Since a great deal more expe-rience with hot-cathode gages is available and hot-cath
6、odedevices are used in the majority of applications, the presentemphasis is fully warranted.1.3 The values stated in inch-pound units are to be regardedas the standard. The metric equivalents of inch-pound unitsmay be approximate.2. Referenced Documents2.1 ASTM Standards:2E297 Test Method for Calibr
7、ating Ionization Vacuum GageTubes (Withdrawn 1983)33. Terminology3.1 DefinitionsThe following definitions are necessary tounderstanding meaningful application of ionization-typevacuum-measurement devices and are useful in differentiatingbetween pressure, density, and flux measuring devices forproper
8、 application and interpretation of low-density molecularmeasurements.3.1.1 Blears effectthe reduction of the partial pressure oforganic vapors within the envelope of a tubulated ionizationgage below the partial pressure that would prevail in theenvelope with a tubulation having infinite conductance.
9、3.1.2 controlled-temperature enclosed gagean enclosedgage in which the envelope is maintained at nearly uniformconstant temperature by suitable means.3.1.3 enclosed ionization gagean ionization gage forwhich the ion source region is enclosed over at least 0.95 4 steradians about the center of the re
10、gion by an envelope at aknown temperature with only a single opening such that allmolecules entering the ion source region must have crossed aplane located outside this region.3.1.4 equivalent nitrogen concentrationthe quantity ob-tained when the ion-collector current of a nude gage (inamperes) for
11、the gas in the system is divided by the concen-tration sensitivity of the gage for nitrogen. This sensitivity isdefined as the ratio of gage ion collector current in amperes tomolecular concentration in molecules per cubic metre ofnitrogen under specified operating conditions.3.1.5 equivalent nitrog
12、en flux densitythe quotient of thecurrent output of an enclosed vacuum gage operating underspecified conditions divided by the molecular flux sensitivityfor nitrogen.3.1.6 equivalent nitrogen pressure:3.1.6.1 For a nude gage, equivalent nitrogen pressure isobtained by multiplying the equivalent nitr
13、ogen concentrationby kTwhere k is the Boltzmann constant and T is the meanabsolute temperature of the walls from which the gas mol-ecules travel to the ionizing region of the gage, averaged asnearly as possible on the basis of relative molecular flux.3.1.6.2 standard equivalent nitrogen pressurefor
14、a nudegage, the value of the equivalent nitrogen pressure is obtainedwhen T = 296K (or standard ambient temperature) is used inthe factor kT.3.1.6.3 For a tubulated gage, the equivalent nitrogen pres-sure in newton per square metre is obtained by dividing the ioncollector current in amperes for a gi
15、ven gas by the pressure1This practice is under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technology and are the direct responsibilityof Subcommittee E21.04 on Space Simulation Test Methods.Current edition approved Oct. 1, 2015. Published May 2010. Originally
16、 approvedin 1966. Last previous edition approved in 2010 as E296 70(2010). DOI:10.1520/E0296-70R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Doc
17、ument Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1sensitivity of the gage in amperes per newton per square metrefo
18、r pure nitrogen under specified operating conditions.3.1.7 gage backgroundthe part of the indicated ion col-lector current produced by phenomena other than ions formedin the gas phase arriving at the collector.3.1.8 gage limita pressure or concentration indication fourtimes the background.3.1.9 ioni
19、zation gagea vacuum gage comprising a meansof ionizing the gas molecules and a means of correlating thenumber and type of ions produced with the pressure orconcentration of the gas. Various types of ionization gages aredistinguished according to the method of producing the ion-ization.3.1.9.1 cold-c
20、athode ionization gagean ionization gage inwhich the ions are produced by a cold-cathode gas discharge,usually in the presence of a magnetic field.3.1.9.2 hot-cathode ionization gagean ionization gage inwhich ion production is initiated and sustained by electronsemitted from a hot cathode.3.1.10 mol
21、ecular flux densitythe number of moleculesincident on a real or imaginary surface per unit area per unittime. The unit is molecules per second per square centimetre.3.1.11 molecular flux sensitivitythe output current of anenclosed vacuum gage per unit molecular flux density underspecified gage opera
22、ting conditions and random particle mo-tion.3.1.12 nude ionization gagean ionization gage for whichthe center of the ion source region is exposed to directmolecular flux (from surfaces not forming part of the gage) inall directions except for a solid angle less than 0.05 4 steradians (determined by
23、the parts of the gage head). Nostructures shall be within one sensing element diameter of anypart of the sensing element unless similar structures are presentduring calibration.NOTE 1The solid angle subtended by a circular disk of radius r withaxis passing through the center point of the solid angle
24、 at a distance y fromthe disk is given as follows: 5 2 1 2 y/y21r2!1/2# (1)For =0.054 , the distance y must equal 2.07 r,avalue which should be easily attainable for typical ionizationgage electrodes mounted on a circular base of radius r.3.1.13 orifice ionization gagean enclosed gage containinga si
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
本资源只提供5页预览,全部文档请下载后查看!喜欢就下载吧,查找使用更方便
5000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ASTME296197020152532STANDARDPRACTICEFORIONIZATIONGAGEAPPLICATIONTOSPACESIMULATORS 空间 模拟器 电离 应用 标准 实施

链接地址:http://www.mydoc123.com/p-527338.html