ASTM_E_2311_-_04_2009.pdf

Designation:E231104(Reapproved 2009)Standard Practice forQCM Measurement of Spacecraft Molecular Contaminationin Space1This standard is issued under the fixed designation E2311;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.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 guidance for making decisionsconcerning the use of a quartz crystal microbalance(QCM)anda thermoelectrically cooled quartz crystal microbalance(TQCM)in space where contamination problems on spacecraftare likely to exist.Careful adherence to this document shouldensure adequate measurement of condensation of molecularconstituents that are commonly termed“contamination”onspacecraft surfaces.1.2 A corollary purpose is to provide choices among theflight-qualified QCMs now existing to meet specific needs.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E595 Test Method for Total Mass Loss and Collected Vola-tile Condensable Materials from Outgassing in a VacuumEnvironmentE1559 Test Method for Contamination Outgassing Charac-teristics of Spacecraft Materials2.2 U.S.Federal Standards:3MIL-STD-883 Standard Test Method,MicrocircuitsMIL-S-45743Soldering,Manual Type,High ReliabilityElectrical and Electronic EquipmentFED-STD-209E Airborne Particulate Cleanliness Classes inCleanrooms and Clean ZonesNOTE1Although FED-STD-209E has been cancelled,it still may beused and designations in FED-STD-209E may be used in addition to theISO designations.2.3 ISO Standards:4ISO 14644-1 Cleanrooms and Associated ControlledEnvironmentsPart 1:Classification of Air CleanlinessISO 14644-2 Cleanrooms and Associated ControlledEnvironmentsPart 2:Specifications for Testing andMonitoring to Prove Continued Compliance with ISO14644-13.Terminology3.1 Definitions:3.1.1 absorptance,nratio of the absorbed radiant orluminous flux to the incident flux.3.1.2 activity coeffcient of crystal,Q,nenergy storedduring a cycle divided by energy lost during a cycle,or thequality factor of a crystal.3.1.3 crystallographic cut,nrotation angle between theoptical axis and the plane of the crystal at which the quartz iscut;typically 35 18AT cut for ambient temperature use or 3940 cut for cryogenic temperature use.3.1.4 collected volatile condensable materials,(CVCM),ntested per Test Method E595.3.1.5 equivalent monomolecular layer,(EML),nsinglelayer of molecules,each 3 10-8cm in diameter,placed withcenters on a square pattern.This results in an EML ofapproximately 1 1015molecules/cm2.3.1.6 field of view,(FOV),nthe line of sight from thesurface of the QCM that is directly exposed to mass flux.3.1.7 irradiance at a point on a surface,nEe,E(Ee=dIe/dA),(watt per square metre,Wm-2),ratio of the radiant fluxincident on an element of the surface containing the point,tothe area of that element.1This practice is under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technology and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Nov.1,2009.Published December 2009.Originallyapproved in 2004.Last previous edition approved in 2004 as E231104.DOI:10.1520/E2311-04R09.2For 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 Document Summary page onthe ASTM website.3Available from U.S.Government Printing Office Superintendent of Documents,732 N.Capitol St.,NW,Mail Stop:SDE,Washington,DC 20401.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.8 mass sensitivity,S,nrelationship between the fre-quency shift and the arriving or departing mass on the sensingcrystal of a QCM.As defined by theory:m/A 5qc/2f2!f(1)where:m=mass change,g,A=area on which the deposit occurs,cm2,f=fundamental frequency of the QCM,Hz,q=density of quartz,g/cm3,andc=shear wave velocity of quartz,cm/s.3.1.9 molecular contamination,nmolecules that remainon a surface with sufficiently long residence times to affect thesurface properties to a sensible degree.3.1.10 optical polish,nthe topology of the quartz crystalsurface as it affects its light reflective properties,for example,specular(sometimes called“clear polish”)or diffuse polish.3.1.11 optical solar ref