Radiometric Standards in the Vacuum Ultraviolet

1 Page 1 NBSMeasurementServices: Radiometric Standardsinthe VacuumUltraviolet NBS Special Publication 250-3 JulesZ.Klose J.MervinBridges WilliamR.Ott U.S.DepartmentofCommerce NationalBureauofStandards Open at page → 2 Page 2 CenterforRadiationResearch TheCenterforRadiationResearchisamajorcomponentoftheNationalMeasurementLaboratory intheNational BureauofStandards. TheCenterprovidestheNationwithstandardsandmeasurementservicesforionizing radiat... Open at page → 3 Page 3 NBSMEASUREMENTSERVICES: RADIOMETRICSTANDARDS INTHE VACUUMULTRAVIOLET JulesZ.Klose J.MervinBridges WilliamR.Ott CenterforRadiationResearch NationalMeasurementLaboratory NationalBureauofStandards Gaithersburg,MD20899 U.S.D... Open at page → 4 Page 4 LibraryofCongressCatalogCardNumber:87-619833 NationalBureauofStandardsSpecialPublication250-3 Natl.Bur.Stand.(U.S.),Spec.Publ.250-3,137pages(June1987) CODEN:XNBSAV Commercialproducts—materialsandinstruments—areidentified... Open at page → 5 Page 5 PREFACE Thecalibration andrelatedmeasurement servicesoftheNationalBureau ofStandardsareintendedtoassistthemakersandusersofprecision measuringinstruments inachievingthehighestpossiblelevelsof accuracy,quality,andproductiv... Open at page → 6 Page 6 ABSTRACT Theradiometriccalibration programcarriedoutbythevacuumultraviolet radiometrygroupintheAtomicandPlasmaRadiationDivisionoftheNational BureauofStandards ispresented indetail. Thecalibration servicesare firstlisted,... Open at page → 7 Page 7 TABLEOFCONTENTS Page Abstract iv LiStofTables viii ListofFigures ix I.Introduction 1 II.Radiometric Standards intheNearandVacuumUltraviolet ... 3 A.SpectralIrradianceStandard,ArgonMini-Arc (140-330nm) 3 B.SpectralRadianc... Open at page → 8 Page 8 Page a.Setup 43 b.SystemAlignment 44 c.ArcCurrent 44 d.DarkCurrentandScatteredLight 44 3.ArgonArc 45 4.BlackbodyLineArc 46 5.TungstenLampStandard 47 6.Calibration ofArgonArcsRelativetoanNBSArgonArc49 B.IrradianceMeasurem... Open at page → 9 Page 9 Page IX.Appendices A-1 A.TheDeuteriumLampasaRadiometricStandard Between115nmand167nm A-1 B.HollowCathodeLamps B-1 C.RareGasDimerLamps C-1 D.Monochromatic SourceofLyman-aRadiation D-1 E.SafetyConsiderations E-1 F.Calibrat... Open at page → 10 Page 10 LISTOFTABLES ^ Page TableI. ' MaximumEmissionCoefficient froma1-atm 'HydrogenPlasmainLTECalculated asaFunction ofWavelength 8 TableII. SpectralRadianceasaFunctionofWavelengthfor a50.0-AArgonMini-arcLightSourcewithanArc P... Open at page → 11 Page 11 LISTOFFIGURES Page Figure1. Comparisons ofspectralradiancesforfarUV sources. Theoutputofthehydrogenarcisgiven forthetemperature ofmaximumcontinuum emission;theoutputsoftheothersourcesareat typicaloperatingconditions 4 Fi... Open at page → 12 Page 12 Page Figure7. Aphotograph ofthehydrogenwal1-stabi1izedarc. Thisparticularphotographshowsgasportsin betweenseveralofthearcplates. Thesearenot normallyusedinhydrogenarcradiometrybutare availabletoadmitgasimpuritiesneededfo... Open at page → 13 Page 13 Page Figure17. Linedrawingofthedeuteriumarclampstandard 36 Figure18. Photograph ofthedeuteriumlampandthe tungsten-quartz-halogen lamphighlightingtheir commonbipostbase 37 Figure19. Absolutespectralirradiancemeasuredasa f... Open at page → 14 Page 14 Page areshownforthefollowingwavelengths: 300nm (+);250nm(o);200nm(x);and140nm(.) 61 Figure27, Thedependence ofthemini-arcspectralradiance ontranslationalalignmentforseveralfield stops,arccurrents,andwavelengths. Thezero... Open at page → 15 Page 15 Page Figure32. Figure33. Figure34, Figure35. Figure36, Figure37, Figure38, Figure39, Spectra!irradiance asafunctionoflampcurrent fortworepresentative wavelengths. Thevalues arenormalizedtothespectralirradiance ata curren... Open at page → 17 Page 17 I.Introduction Thevacuumultraviolet (VUV)regionofthespectrumhasbecomeimportant inseveralareasofresearchanddevelopment. Theseincludespace-based as- tronomy andastrophysics, thermonuclear fusionresearch, ultraviolet laser... Open at page → 18 Page 18 ringthesecondarystandards canbeuseful inmakingpossiblemorefrequent calibrations. Also,thesecondarystandardspossesssomeusefulproperties notcharacteristic oftheavailableprimarystandards suchas,forexample, emissionoverarela... Open at page → 19 Page 19 II.NBSRadiometricStandards intheNearandVacuumUltraviolet A.SpectralIrradianceStandard,ArgonMini-Arc(140-330nm) , $P250No.40010S(7.611 Anargonmini-arcsupplied bythecustomer iscalibrated forspectral irradiance at10nminterv... Open at page → 20 Page 20 I CM 1 E o 10- 10' 0) 10' ifi £ 10 -I J10 -2 10 -3 Lya Figure1. "1 \ 1 1-I2500K BLACKBODY BLACKBODYLIMITEDLINES FROM12500KARC IcmHYDROGENARC 30WATT DgLAMP / J L TUNGSTEN STRIP LAMP 100 200 X[nm] 300 400 Comparisons ofspe... Open at page → 21 Page 21 5.0 4.0 3.0 (D ^2.0 UJ02 124nm 250nm oo 200nm oOOoooOOOoOo °°oOoo 150nm 16000 Figure2. 18000 20000 22000 T(K) Theemissioncoefficient fora1-atmhydrogen plasmainLTEasafunctionoftemperature for severalwavelengths: 250nm ( )... Open at page → 22 Page 22 III.Apparatus !A.PrimaryStandards '1.TheHydrogenArc a.PhysicalPrinciples Ahightemperature wal 1-stabi 1izedsteady-state hydrogen archasbeen developed asourprimarystandardofspectral radiance. iThistypeofarc lendsitselftos... Open at page → 23 Page 23 J2 £ E UJU 3- mosUO/W ] t3"O d) M> <u (/) jO fT2o •*-> (/) 1 ' — »-> <TJ JC 4-> E ElO 1E CVJCO 03 C o •»-> O <^in CT QJO Q. E QJc d) E fO a) ^ 4-J >> +-> •r— (/)d) "O (->to E CO C o o O) d) 4-> • o a)o OCO d)»-> Cl "O»->... Open at page → 24 Page 24 E o 0)— c 0) U 0) sis 3 E X c o o c IL > I 0) I" I CO O ood rHo o COCD • o • o • o • o • o oo00 I> oooooooooooooo oooooooooooooo OOiOLOOOC^i^^OOt>iO»OLOO I>I>I>OOOOa^OiOT-liHl>CDCDCD rHTHT-lrHrHTHTH<NOq<MrHrHTHrH coooa5(... Open at page → 25 Page 25 smallsampleoftheregionisobservedasindicated inthefigure. First,it meansthatthealignment precision, whichwasresponsible formuchofthe uncertainty inthelowpowerarcmethod, isnotcritical here. Second, it meansthatthearccurren... Open at page → 26 Page 26 VACUUM SHUTTER-MIRROR Figure4. AIR Schematicofthehydrogenwal 1-stabi 1izedarc. A cutawaytopviewdrawingofoneofthearcplates illustrates theflowofcoolingwaterthrough speciallymachinedchannelswithineachplate. Thesymbolsinthe... Open at page → 27 Page 27 SPATIALRESOLUTION X I GAIN X10 -1.0 05 0 0.5 +L0 R(mm) Figure5.Theradialdependence ofthehydrogenarcspectralradianceat160.6nmforan arcaxistemperature ofabout19,500K.Theintenseoff-axisradiation isdue toLymanbandmolecularem... Open at page → 28 Page 28 betweentheelectrodes. Theestimatedlengthofthehomogeneous hydrogenarc plasmawasthustakentobe5.3cmwithanuncertainty of5%(2a). Spatialresolution isnotmuchofaproblemforthehighpowerarcsince theemissioncharacteristics arenearl... Open at page → 29 Page 29 o lO O U> in o in in ft Iw I HO— I i-O— I I I I I I E c [ ,_J3js,.ujujj_uioM ]33NViavaHVHlDBdS UJ (—!->ra _J 3 +J coOJ !-> I- IT3 r3cu<uE Eot_ 00cn3 ' <T3 CO>^ CLOMo !->co O jD t_o (O du Q.o c Olr— <u -Q oc= l_ "— - ora... Open at page → 30 Page 30 (/I3 tJ-Q C_ o>, Q.t- +-> a>o (/)"O o«- Ql (Oc t_<U OO 4->t- o-o t_C (T3-r- • 3-aCO o(uc I- (/>o t- +J Q.^O I/) (T3 ( — .-ECL ^t-Q. I—O(O c t_ ••(-><u oo^ t-c+J (Oo O) -o«-«- O)fOo N <*- •1-<U I— l/>"O •.-<uai jD^-a 4->... Open at page → 31 Page 31 Insummary, ahighpoweratmospheric pressurehydrogen arccapableof operating attemperatures ontheorderof20,000 Khasbeenexaminedtheor- etically andexperimentally andfoundtobesuitable asaprimaryradio- metricstandard intheVUV.... Open at page → 32 Page 32 Figure8. Explodedviewofthemajorcomponents ofthearc: electrodes (onehasbeenremoved),twoarc plates,abakelitespacerandgaskets. -16- Open at page → 33 Page 33 I (a)Aschematicillustrating themethodofarc plateconstruction, (b)Theassembledarcplate, (c)Aphotograph ofanarcplatecutawayinthe centertoexposethewaterchannels. -17- Open at page → 34 Page 34 mayarisefromsmallpressurefluctuations intheelectroderegionsdueto occasionalshiftingofthearctermination points. Iftheyarepresent,these instabilities aremanifestedbyavaryingarclength. Apolycarbonate plastic extensiontubeis... Open at page → 35 Page 35 Figure10. Anend-onviewofthehydrogenarcoperatedat100amperes. Thetemperature formaximumcontinuumemissionhasbeenexceededinthevicinityofthearc axisforwavelengths inthevisible. Thisismanifested asaslightcontrast betweenthebri... Open at page → 36 Page 36 argongas,asimplegashandlingsystemisrequired. Thearcisstruckat 20Abyshortingthecathodetotheanodewithatungstenrodconnectedtothe cathodepotential andslowlywithdrawing theroddowntheaxisofthearc. Afteradjusting theposition of... Open at page → 37 Page 37 2.BlackbodyLineArc Theshortwavelength limitofthehydrogenarcatabout124nmisdeter- minedbytheonsetoftheStark-broadened, opticallythickLymanlineseries ofatomichydrogenthatdominates thespectrumbetween94nmand124nm. Sincethesho... Open at page → 38 Page 38 first,thecontinuumemittedbythearcmixture at250nmismeasuredand calibrated atlowspectral resolution usingthetungstenstriplampandthe air-pathpredisperser andmonochromator ;andsecond,thepeakofthecarbon lineiscalibratedwithre... Open at page → 39 Page 39 -23- Open at page → 40 Page 40 Tomeetthelackofadequatetransferstandards inthefarUV,theargon mini-arc wasdeveloped atNBS.^^ Thissourcecanbeconveniently applied asaradiometric transferstandardwithoutthelimitations ofthedeuterium lamp. Thewavelength rang... Open at page → 42 Page 42 Theseelementsarepresentduetoairandwatervaporinthearcchamberand gashandlingsystem. Thepositions ofthegasinletandoutletportsare chosentokeepallsectionsofthearcchamberthoroughlypurged. Theargon isadmittedtotheinletportsthro... Open at page → 43 Page 43 10"C 1 1 > r 110150 190230270310350 X[nm] Figure13. Spectralradianceasafunctionofwavelengthfor amini-arcwithanarcplatediameterof4.0mm operatedattwodifferentcurrents: 50.0Aand 25.0A. -27- Open at page → 44 Page 44 OO-^THCOCOOOOOOOCDOOOiCiOO-^OC^incNCM^OOO^ OOO^O^OOt>t>tDiOT}<TfC<lTHO^OO«OTj<<MOl>iOCDTt(MOlCOCO a>o^oooooooooooooocoooooooc^t>t>^-t>l>c^)^£>c£>;Dt^>lo»0"^ ooooooooooooooo'oooooooooooo C£)OlCOO-^i-tOCOC30r-lCrjCOCOOOCOl... Open at page → 45 Page 45 issnail(f/200isusedforcalibrations withthehydrogenandblackbodyarcs) andnotconvenient forthecalibration ofmanyopticalsystems. Foratrans- ferstandard, ontheotherhand,thearclengthdoesnotneedtobeprecisely knownaslongasitisar... Open at page → 46 Page 46 1VN9IS 1VN9IS O)t— I t-o •r— -30- Open at page → 47 Page 47 TableIII.SurveyofEmissionLines Appearing inSpectrumofMini-arc Radiancerelative X(nm) Identification tocontinuum^ 115.22 0I 1 116.79 NI 1 117.69 NI 0.3 118.94 CI 0.3 119.38 CI 1 119.99 NI 30 121.57 HI 100 124.33 NI 5 126.... Open at page → 48 Page 48 presentduetotracequantities ofwatervaporthroughoutthesystem. These impuritylinescanbeseeninFig.14whichisaphotoelectric scanofthe spectrumbetween115nmand320nm. Thehalfwidths ofthelinesareonthe orderof0.01nm,andthelinesare... Open at page → 49 Page 49 10- 10 10^ 10 -4 4' ^-"l"""^IISOOKBLACKBODY BLACKBODYLIMITEDLINES FROM11800KARCPLASMA U Lya NBSHYDROGENARC ARGONMAXIARC ARGONMINIARC D2LAMP TUNGSTENSTRIP/LAMP 110 150 190 230270310350 X[nm] Figure15. Comparison ofthespec... Open at page → 50 Page 50 -t-> 3 O O) to -o 0) CL E E 3 t-> T3 OQ. •I-o 4-> ( — (Oa> t-> <uc Q.a» o Q. cuE t->>— a>N c+J •r-I_ +J(T3 (a3 c_cr +j (/)<u 3^ r—+-> •r-O +-> a •f--a +->0) (O.— E'O (Uoi o 00s o T3 3C_ a>Q. 3 U.CO Open at page → 51 Page 51 itmayexhibit avariability inthepositioning ofthedischargeontheelec- trodesfollowing eachignition; anditsagingcharacteristics arenotwell known. Onbalance,however,theadvantages ofthedeuteriumlampoutweighits disadvantages m... Open at page → 52 Page 52 3cm 9.5cm Figure17. Linedrawingofthedeuteriumarclampstandard, -35- Open at page → 53 Page 53 C 4-> "O fO e CI. Ee 3 l_ OJC ^->u rjcn O)o o • ^OJ OJ to n3 +j tz t_ OfO I/) 13o CTCL CL tl JD c_OJ cr>+->c O I/)o E OcrE 13o £X o 00 1— I {_ 13 -37- Open at page → 54 Page 54 placedinthebasesothatthelaserbeampassesthroughthecenterofthe 1mmdiameterdischarge-constricting apertureinsidethelamp. Thepitchand yawofthelamparethenadjustedaboutthecenterofthe 1mmlampaperture fortheconditiongivingmaximu... Open at page → 55 Page 55 10 0 50 100 150 200 250 300 350 A(nm) Figure19. Absolutespectralirradiancemeasuredasafunctionofwavelength ata distanceof50cmfromthefieldapertureforfivedifferentcontinuumsourceswiththe indicatedpowerrequirements. Thespect... Open at page → 56 Page 56 light, a0.25mfocallengthEbertmonochromator hasbeenmatedasapre- dispersertothe 1mairmonochromator. TheEbertinstrument isequippedwith apairofinterchangeable gratingswithruledareasof64mmx64mm. One gratingwith arulingof2365L... Open at page → 57 Page 57 temperaturevariation involtageiswithin±50ppm/°Cintheoperatingrange0 to50°Caftera30minutewarmup,andthelong-termdriftinvoltageisless than0.01%/hror0.03%/24-hr atconstantinputlinevoltage,load,andambient temperature, alsoaft... Open at page → 58 Page 58 o (/) a {- 73 o (/> CD Q. E • oe <-O OTJ •4-> Q.<T} 4->C OJr- (/I cu M--O o-o o OJ oa. 00CO o CM O) -42- Open at page → 59 Page 59 IV.CalibrationMethods A.RadianceCalibrations 1.Introduction Spectralradiance, L;^,isdefinedintheIntroduction astheradiant poweremittedbyasourceperareapersolidangleperwavelength interval: L;^=[wattscm'^sr"inm"i], Acalibra... Open at page → 60 Page 60 diansorf/200. Thesearerathersmallgeometrical limits,butarenecessary tolimitthevariation inradianceto1%withintheobservedopticalbeam, b.SystemAlignment Beforeplacingthearcinposition, theposition ofthetelescope is adjusted... Open at page → 61 Page 61 110nm. Asthegrating isscannedtowardshorterwavelengths, thesignal graduallydecreases andfinallybecomesconstant atavaluegreaterthanthe darkcurrent. Sincenoradiation istransmitted atthesewavelengths below about113nm(theMgF2... Open at page → 62 Page 62 lengthscoveredbythehydrogen arc,signalsarealsomeasured atshorter wavelengths extendingto115nm. Inthisregion,however,therearenumerous linesinthespectrumfromminuteairimpurities. Theselinesaretypically resonancelinesandaree... Open at page → 63 Page 63 extendingtherangeofcalibrationdownto115nm. Byinterpolation thecali- bration isextended toallwavelengths inbetweenthelines. Asufficient numberoflinesareavailabletorestricttheinterpolations toshortinter- vals. Sincetheslit... Open at page → 64 Page 64 -48- Open at page → 65 Page 65 alaserwithanalignment devicetosettheangularorientation. After ignition,thelampistranslatedslightlytopreciselyadjusttheimageposi- tionontheentranceaperture asspecified inthelampcalibration report. Thentheconcavemirrorbetw... Open at page → 66 Page 66 allycontains awindow,andthusthecalibration ofthearcmustinclude a separatemeasurement ofitstransmission. Thewindowtransmissionmeasurement iscarriedoutbyremovingthewindow fromthearcandinstalling itinaholderwhichenablesthew... Open at page → 67 Page 67 =0) OQ. O< I oEX 5<o •r— s <L) (/)C OO x:-r- E-a ,—t_ O) •-- -a'o +j1/1 •r-<u o> <X3-r- t_4-) t-fa 0) (_ O)c: 4->o O) e-a OO) •r-c -O-r- E t_{_ OO) C-+J OT3 <D a.(/) 00•- >^ <J O) •u 0) u- 4- oa> <D O O (_ Q. •A "O oOJ •... Open at page → 68 Page 68 metricfactordependent ontheaperturedimensions andtheirlocations rela- tivetothelamp. Thisgeometric factorcontainstheinformation onthe effectiveareaoftheemittingsource,thesolidangleoftheradiationbeam incidentuponthefielda... Open at page → 69 Page 69 G) C CO <u o t- 3 o in Q-e S13 O13 au a (-> o Q.C 3-r- +-> CU(U (/)o c XTr- +->-o -O <+-t_ o«- o IT3t_ E 4-> 0)U ^<U oa. on i/> CO cvj CU 3 0) -53- Open at page → 70 Page 70 whereEj(Xq)isthespectralirradianceofthestandardsource. IfEq.(8),withX=Xq,iscombinedwithEq.(9),ycanbeeliminatedto give S'x(Xo)S,^(Xo)E^(Xo)S^(x) ^^^^^ s'iIXq) l^TTJ "-R^^^- ^^^^ FromEq.(10)theabsoluteirradiance oftheunkno... Open at page → 71 Page 71 Q. -55- Open at page → 72 Page 72 Thus,theabovemeasurements determine theirradiance oftheunknown source,butonlyonarelativescaleaslongasthevalueoftheconstant^in Eqs.7and8isunknown. Toobtainanabsolutescale,theirradiance ofthe unknownsourceiscomparedinthene... Open at page → 73 Page 73 ninetherelativespectraldistribution, theexactdistancefromthelampto theentranceaperture isnotcritical. Thisdistance issetatapproximately 50cm.Thelampisignitedandoperatedfor10minuteswithanargonpurgeof atleast10il/min. This... Open at page → 74 Page 74 10 20 30 40 50 60 ARCCURRENT(A) Figure25. Thedependence ofthemini-arcspectralradiance onarccurrentforseveralrepresentative wavelengths . -58- Open at page → 75 Page 75 V.Uncertainties A.ArgonMini-ArcRadianceStandard 1.PrimaryStandards Thebasicuncertainties inthespectralradianceofthemini-arcaredue touncertainties intheprimaryradiometric standards. Aswasdiscussed in Sees.III-A,1and2,theh... Open at page → 76 Page 76 c •*-» c7 0) Co 4, c 1 cr 0)E OE rodu 1 E 30-n UCO o 1 in "D 0) 1 u.o 0) 3 eqX c cro to ren CsJ oc 0) u (J i-arc diam Wav c Micr 3 O >o> -4-» a H O^OI>l>rHOiOCOCDiOLOOO OOrHrH(>i CO00<NOilOOl> OOOOOOOOOOOOOiO coi-io^i>ir... Open at page → 77 Page 77 LU > I- < -J LU CC LU CJ < DC -J < CC \- o LU a. 0.8 0.9 1.0 1.1 PRESSURE(ATM) 1.2 Figure26, Thedependence ofthemini-arcspectralradiance onthearcchamberpressure. Thearcchamber pressure, intheabsenceofanexhaustmanifold, i... Open at page → 78 Page 78 isgreaterwhenthepurgerateishigh. However,toolargeaflowratecan causechanges inthespectral radiance ofthecontinuum. Itcancoolthe plasma (aneffectwhichtendstodecrease theradiant power)orcausea pressurization ofthearcchamber... Open at page → 79 Page 79 CO o CO o 'a: o 6 e _i CO COz d< o I o I 00 o I nVNOIS3AllV13a Ol •4^ • I/) ,.,^^^ OJ13 X o - — O) cz ^->•1—C t_ "Oo ocoLD > o«^OJ <D O •— ' (/) (/) "O t_c:c -— - "3 oo •1—+ Q.s (/)o 4_> OJ ,—£ cr t_ QJ t_o t_ o"4—o{_ (... Open at page → 80 Page 80 0) o 00 UJ LU DC LU Q LU -J O z < I- < o nvNOis3Aiivn3a •• o «/> **-c •Mo o O+Jc_ +-> IT3 >> T3 </)C«t O 1 CcOO fOo CVJ Q.a> x:«/)c oO)C 4->(-o t-o CLO u »o +-><D 1_ rO0)> EOx: cCO4-> a> CUt_>> O c <oc< cco ooE +J•-> «J... Open at page → 81 Page 81 Fig.13andTableII. However,thisuncertainty usuallycanbeavoideden- tirelybyproviding fineadjustments formaximumsignal, forexample, by translation ofthelightsourceitselforofthearcimagethroughuseofan adjustable reflectingmir... Open at page → 82 Page 82 Inaddition, bothshortandlongtermstabilitymustbeconsidered to evaluatethereliability ofthemini-arc asasecondaryradiationstandard. Shortterminstabilities mightbecaused,forexample,byelectrodeeffectsin whichthearctermination... Open at page → 83 Page 83 7.GasImpurity Itwasstandardprocedureduringthevariousexperiments describedhere touseultrahigh purityargon(99.9995% pure). Ifcommercial gradeargon (99.9990% pure) isused,thecontinuum intensities areunchanged, theonly effec... Open at page → 84 Page 84 TableV.ErrorBudgetfortheSpectralRadiance Calibration oftheArgonMini-Arc Source Contribution {%) PrimaryStandard (s) above140nm below140nm Arccurrent ( r) Gasflow(r) Pressure (r) Alignment (r) Reproducibility (r) Shortter... Open at page → 85 Page 85 Calibration hasbeenperformedusingtwoprimarystandardsources: thehydro- genarcfrom130nmto330nnandtheblackbodylineradiatorfrom114nmto 130nm. Themini-arc hasthefollowing principal features: (1)asteady- statereproducible sour... Open at page → 86 Page 86 TableVI.ErrorBudgetfortheSpectralIrradiance Calibration oftheArgonMini-Arc Source Contribution (%) Standard (s) 5.3 Diffuser (s) <6 Diffraction (s) , 0.5 Spatialresolution (s) 4 Wavelengthdependence fromaboveeffects(s) 0... Open at page → 87 Page 87 in in oo; x: -l-J-t-> "O >c: (/) (/) 3 c o "4- u 14- O) en«-o 0) x:o cn. r3(/)faQJ I/)a>-aQJ cc_ o TJ *'"* •»-)T3 »-> cro 'O{_ *CO CT14-) ^O) I/)o -4-> •r— O)4-5 u d -a13 O) •r—*^ u "O •1— c fO TJoC— t_ -ooo. t c cr cz c... Open at page → 88 Page 88 jectedtoradiometric scale intercomparisons ,bothinternal i»18andinter- national. ^5The2auncertainty intheabsolutespectralradianceofthemini- archasbeendetermined inSec.V-Atobe5.3%between140and330nm.The mini-arcwaslocated5... Open at page → 89 Page 89 200 250 300 350 WAVELENGTH (nm) Figure30. Typicalspectralirradiance ofa1000W quartz-halogen lampanda30-Wdeuteriumlamp. -73- Open at page → 90 Page 90 AI347 ROTATION -2** -1* 0 +r +2* ROTATION Figure31. Thedependence ofthespectralirradianceupon pitchandyawofadeuteriumlamplocated50cm fromal-cm^aperture. A2°angularchangeis equivalent toa1.76-cmtranslationalchange. -74- Open at page → 91 Page 91 C.DeuteriumLampIrradianceStandard 1.SpectralIrradianceCalibration Figure30illustrates thespectrumofatypicaldeuteriumlampascom- paredwithacalibrated 1000-Wtungstenquartz-halogen lamp. Thespectral irradianceofthetwotypesof... Open at page → 92 Page 92 1 1 1 1 1 1 1 1 1 1 T ~i i r i 1 1 1 1 1 1 1 • w A • • t ... 1 i — i •250nm i 350nm • ' 1 - • • 1 1 1 1 1 1 1 1 1 1 1 0 .3 .6 .9 1 CURRENT(A) Figure32. Spectralirradiance asafunctionoflampcurrent fortworepresentative wav... Open at page → 93 Page 93 1000 I I 100 I \ \ \ \ I 0 10 20 30 40 50 60 DISTANCE(cm) I Figure33. Spectralirradiancemeasurements asafunctionofdistancebetweenthedeuterium lampenvelopeandal-cm^fieldstop.Resultsexpectedbyassumingtheinversesquarelawand... Open at page → 94 Page 94 heatsandisindangeroffailure. Betweentheselimits,thespectralirradi- ancecanbevariedabout afactorof10andisnearlylinearwithcurrent, withaslopeweaklydependent onwavelength. Itcanbeseenthathighpre- cisioncurrentmeasurements a... Open at page → 95 Page 95 attempttogeneralize onthelampbehaviorduringthefirst100hoursofits 1ifetime. Therewasalsoavariation associated withstrikingthelamps. Some lampswouldproducemoresignal if,afterthenormalwarmuptime,theywere switchedoffandonaga... Open at page → 96 Page 96 TableVII.ErrorBudgetfortheSpectralIrradianceCalibration oftheDeuteriumArcLamp Source Contribution (%) Standard (s) 3 uirfuser(s) <3 Alignment (r) 1 Lampcurrent(r) 0.3 Solidangle ( r) 1 Variability (lampspreselected) (r)... Open at page → 97 Page 97 heatedbyradiation fromthedeuterium lamp. Theinclusion ofthisfinal contribution whichisgiveninTableVIIgivesanuncertainty of6%to10%in thewavelengthregionfrom195nmto167nm, 7.Summary Asetofcommercially availabledeuteriumlamp... Open at page → 98 Page 98 VI.QualityControlThroughIntercomparisons A,Introduction Inradiometric workthedemonstration oftheconsistency ofindependent primarystandards isessentialtothefoundation ofvalidsystemsofcalibra- tion. Thisprocessinvolvesboth... Open at page → 99 Page 99 tungstenstriplamp,theminimumwavelength canbeloweredtoabout124nm.i Inthepresentcomparison awallstabilizedarcdischarge isseededwithC,N, and0atomstoproduceopticallythickblackbody limitedresonancelinesin theUVandVUV. Thecali... Open at page → 100 Page 100 C.TheHydrogenArcversustheDESYSynchrotron 1.DeuteriumLamp InthissectionwecomparetheUVradiometric scalesofthreelabora- toriesthroughthespectral radiancecalibration ofdeuterium lamps.25jhe laboratories aretheMaxPlanckInstit... Open at page → 101 Page 101 ThePTBcalibration facilityatDESYallowsthesimultaneous measurement ofsynchrotron radiation inthevisibleandVUVspectralregionswithatwo- monochromator system. Onemonochromator looksatthevisibleradiationfrom thesynchrotron an... Open at page → 102 Page 102 ' ' ' — .CD 5:CL Q T— r TP-T-r—rT— I r o nI I I I I I— r 'o ' 'i—j _i I I I CO Q_CD 2:z £ o 00 o is est O •LO LO Q o I I I I I— I r ,.1 ' ' ' ' ' ' 'o o •o cn o •IT) rsi o •o rsi o 0 • +-> Q.-a+1 EO) N E •-> 3 t_0 0)c 4-... Open at page → 103 Page 103 purgedwithhighpurityargongas,thusprotectingthelampwindowfrompossi- bledeterioration duetocondensation ofUVphoto-dissociated hydrocarbons. Followingthecalibration ofthelamponthevacuumUVcalibration facil- ity,thelampwascal... Open at page → 104 Page 104 VII.Acknowledgments Theauthorsaregrateful forthesuggestionsmadebyWolfgang L.Wiese, ChiefoftheAtomicandPlasmaRadiationDivision, JamesR.Roberts,Group LeaderofthePlasmaRadiationGroup,andtheCALCOMcommitteememberswho reviewed... Open at page → 105 Page 105 VIII.References 1.W.R.Ott,K.Behringer, andG.Gieres,Appl.Opt.14,2121 (1975). 2.J.R.RobertsandP.A.Voigt,J.Res.Nat.Bur.Stand.75a ,291(1971). 3.W.R.Ott,P.Fieffe-Prevost, andW.L.Wiese,Appl.Opt.12,1618 (1973). — 4.W.R.OttandW.... Open at page → 106 Page 106 M.C.Castex,M.Pouey,andN.Pouey,eds.(CentreNationaldela RechercheScientifique,Meudon,France,1977),Vol.3,p.123. 22. W.R.Ott,J.M.Bridges,andJ.Z.Klose,Opt.Lett. 5^,225(1980). 23. J.C.Morris,J.Quant.Spectrosc.Radiat.Transfer 9... Open at page → 107 Page 107 40. J.Z.Klose,PortableUVRadiometricStandards(contractreportforthe NationalOceanicandAtmosphericAdministration), September, 1981. 41. J.Z.Klose,J.M.Bridges,andW.R.Ott,J.Opt.Soc.Am.72.,1804 (1982). 42. R.T.Brackmann, W.L.F... Open at page → 109 Page 109 IX.Appendices A.TheDeuteriumLampasaRadiometricStandardBetween115nmand167nm AtNBSaninvestigation hasbeencarriedoutwiththeaimofextending theVUVrangeofspectralirradiance ofthedeuteriumlampdowntotheMgF2 cutoffat115nm.^^ Thee... Open at page → 111 Page 111 1— r T— r T— r 00 U • AO *-) I/) oD JQJ >• t_n3 >> <s> 4-) US I/)</) •r-iO en c_ QJ a: *->> he O O +J 4->'O «_ <s> ifi ro OJ X o UJ -J •1—(/) I/) (/)"3 OJa. o-o cc QJ'O QJ QJ c XQJ QJ :3 CD o*-4U.ii-UjQiujzoujcn A-3 Open at page → 112 Page 112 "1 i Open at page → 113 Page 113 B.HollowCathodeLamps Asourcewhichisgaining infavorforthecalibration ofspaceexperi- mentsisthemetalraregashollowcathodedischarge lamp. Twoversionsof thislamphavingaplatinumorplatinum-chromium cathodeandafillingofneon gas^... Open at page → 114 Page 114 B-2 Open at page → 115 Page 115 C.RareGasDimerLamps Anothertypeoflampwhichhasreceivedconsiderable attention asacali- brationsourceintheVUVforspaceexperiments istherf-excited rareyas dimerlamp,'*° Theselampsemitsignificant radiation intheVUVbutonlyover... Open at page → 116 Page 116 Figure38. Thespectralradianceofanrf-excitedkryptondinerlamp. Open at page → 117 Page 117 D.Monochromatic SourceofLyman-gRadiation ForsometimetheVUVRadiometryGroupatNBShasbeenconcernedwith development ofacalibrated sourceemittingtheradiation ofanindividual atomictransition.**^ Suchasourcewouldbeofvaluesinceit... Open at page → 118 Page 118 o o o CM o o o o CM CO E o LL CM ( % 't—0} t_ 1 1 Ql </) E0)3 •1—JZ•1—5 <l> r~ c 14—S_<o O3 c_ 0) fO0)4_> x:Ea; O-Qc (O T3 Q. 1C C •!—(Q <aE 0^ 1 CO I4_-Q o >»1- •4->0) •1-5 (O c</1 (U(V"O (O t_ >) 4_> 4->4_>(_ (4—-f— o... Open at page → 119 Page 119 I o D •a o . s -2 CM CD 3- o .^ COCM GO^ a:)a:>00 cr» • • • • • ooooo 00COCOCD COCMT-H • O • o • o • o oCD00 CM CMr— 1 CDCOCOCM 00o COCOCO Ooooooooo •o • o • o • o • o • o • o • o • oo • o oooooooooo CMCO^iOOOOOlO r-HCMC... Open at page → 120 Page 120 tinuumabove«170nmwaseliminatedthroughtheadditionofastandardinter- ferencefilterwiththespecifications givenabove. Theirradiances ofthesourcewereobtainedbyapplyingtheradiance-to- irradiancetransfermethoddescribedaboveinSec... Open at page → 121 Page 121 E.SafetyConsiderations 1.Extremecautionshouldbeexercisedwhendealingwithhighvoltages andcurrents. 2.Beforeanarcoperation isbegun, achecktoensuretheelectrical isolationoftheanodeandcathodeshouldbemade. 3.Beforeanarcoperati... Open at page → 123 Page 123 0-M> U.S.DepartmentofCommerce NATIONAl.SUMKAUOTSTANDAftm AppendixF-1 washimoton. mzm REPORTOFTEST October22,1985 VUVSpectralRadianceofArgonMini-Arc Anargonmini-arclightsource was calibrated inthewavelengthrange118-335nm.... Open at page → 124 Page 124 ArgonMini-ArcCalibration Argonmini-arclightsourcesarecalibrated inthewavelengthrange118nra to335nmwiththeNBSargonmini-arc. Thelatterisasecondarystandardand hadbeencalibratedpreviouslywiththreeprimaryradiometricstandards,... Open at page → 125 Page 125 c)Thefnumberoftheopticalsystemwasdefinedbyafieldstoplocated infrontofthefocusingmirror(f/100). 0)Thespectrometer resolutionwas0.1nm. e)Ashortgascellislocatedbetweenthemini-arcandthevacuumsystem. Itisnormallypurgedwitharg... Open at page → 126 Page 126 indicatestheapproximaterelativeintensityofthelinesrelativetothearyon continuumforabandpassof0.25nm.Figure2isastripchartrecordingofa photoelectric scanofthespectrumundertheseconditions. Thewidthofthe linesisinstrument-lim... Open at page → 127 Page 127 Table1.CalibratedspectralradianceinunitsofWcm-^nin"^sr~i.Theareaof thelightsourcewhichiscalibrated isthecentral0.3nmdiameterregion. Valuesofthespectralradiancearegivenforanarccurrentof38.00A. X(nm) Spectralradiance, usin... Open at page → 128 Page 128 Table2.Surveyofemissionlinespresentinthe38Aargonmini-arc spectrum. Thespectrometerbandpassis0.25nm. Radianceoflinepeak XCnm) Elenent relativetocontinuum 115.22 - • __-._ 0I ' 1 - - 116.79 NI i 117.69 RI 0.3 118.94 CI 0.3... Open at page → 129 Page 129 Table3.Uncertainties inthemini-arc spectralradiancecalibration. X(nni) uncertainty (2a) 250-335 4% 140-250 9X 118-140 20% (F-l) Open at page → 130 Page 130 O CO o CD o CD o O d£ OJ o I o 1 o I CD o I CO < cr 1- .—X S- GJ »— >C«J 0)00 U>1 r- o»—o *^laSI EJ- E -= CQ) *-> •I-4J5 to "IVN9IS3AllV13a c-o OOJ c: ccr. o -<- o •»-r— fOo>> -o ceo fO1—f3 J-X s- CCJw ON1- OJCO uJ= ro <... Open at page → 131 Page 131 cc 1/) 3 to *a c/) raE <u U— O •— O) Eo. =3 S_4-> u=! CDE C-o l/)*J o u s. TO 1 c E cs- ora cr s-"o to <<o ou— oo COOJ nto O) *jsz u- oo 4-) c reo o I/) cto o E 'oo LD i_E a<a; ^>^ CTiOto •r-J>> 2ZfOto cn 1THDIS 1TK5I$ (... Open at page → 132 Page 132 I .... *1 Open at page → 133 Page 133 PCWMNBS-44X (RCV.I*-H) U.S.DEPARTMEhTTOFCOMMERCE AppendixF-2 NATIONAL.BUREAUOFSTANDARDS WASHINGTON,O.C.20234 April16,1984 AnArgonmini-Arclightsourcewascalibratedforspectral irradiance inthewavelengthrange138mmto335mmbase... Open at page → 134 Page 134 Inthiswaydamagetothearcwindowdoesnotresultinthelossofa calibratedlightsource. Also,itispossiblethroughsuch substitution ofacalibratedwindow,toperiodically checkfor deterioration ofthewindowdueto,forexample,condensation o... Open at page → 135 Page 135 Theirradiance ofthemini-arcisafunctionofpress-re.The valuesinTable1applytoanambientpressureof1atm.The irradianceatotherpressures isgiventy E(p) =(1.57p -0.57)E(0) wherepisthepressureinatmosphereand^(0)istheirradianceat1... Open at page → 136 Page 136 FortheDirector, WolfgangL.Wiese,Chief AtomicandPlasmaRadiation Division CenterforRadiationResearch JohnM.Bridges,Physicist AtomicandPlasmaRadiation Division CenterforRadiationResearch Attachments. (F-2) F-2-4 Open at page → 137 Page 137 Table1.Calibratedspectralirradiance ofArcinunitsofWcm"^ nm"^.Valuesofthespectralirradiancearegivenforan arccurrentof40.00A,andatadistanceof50.0cmfrom thecenterofthearc. Estimateduncertainty is^6%forX>^200nmand^10% forX<2... Open at page → 138 Page 138 Table2.Surveyofemissionlinespresentinthe40Aargonmini-arc spectrum. Thespectrometerbandpassis0.25nm. Radianceoflinepeak XCnm) Element relativetocontinuum 115.22 0I 1 116.79 N T 1 117.69 KI 03 118.94 rT 03 119.38 r w T 1 1... Open at page → 139 Page 139 Figure1.Positionofarcrelativetoentranceaperture t I 8 I I t t I { L_ -5^ --f-S -/ O / 2^3 -f- AngleofRotation(degrees) Figure2 Relativesignalvsangleofrotationofarcaboutitscenter. (F-2) F-2-7 Open at page → 140 Page 140 ra cc u — u cr3 ct/i fO t/) *B U i-u u CI ' •— E u3 CJ rQ I/) o CJ s- 1 S_ oa c~ i_o 1/) <<a oU— oo • (U o to OJ oo c la o3 a c o 3c 'oo 1/1m (U s- Q.'a> > oCO >> CO w 3 TTKSIS (F-2) F-2-8 Open at page → 141 Page 141 FO!»MNBS—IS« (WEV.ii-Te I U.S.DepartmentofCommerce NATIONALBUREAUOFSTANDARDS AppendixF-3 Washington, d.c.20234 REPORTOFTEST VUVSpectralIrradianceofDeuteriumLamp TheSpectralIrradianceofDeuteriumLampEF132wascalibratedforth... Open at page → 142 Page 142 operatedinsideanenclosure y^hichwaspurgedwithargontoprevent absorption. Anargonflowrateof20imin"'^waschosen,sinceanincrease inthisrateproducednochangeinthesignalat170nn. Thespectralirradiance ofD2lampEF132isgiveninTable... Open at page → 143 Page 143 LampEF132 Table1.SpectralIrradiance ofLampat50cmforcurrentof300ma. Wavelength SpectralIrradiance X(nm) (W/cm3) 260 0.261 200 0.496 195 0.486 190 0.456 187 0.431 184 0.402 182 0.377 180 0.352 178 0.323 176 0.284 174 0.260... Open at page → 144 Page 144 NBS-n4A(REV.2-8C) U.S.DEPT.OFCOMM. BIBLIOGRAPHICDATA SHEET(Seeinstructions) 1.PUBLICATIONOR REPORTNO. NBS/SP-250/3 2.PerformingOrgan.ReportNo.3.PublicationDate June1987 4.TITLEANDSUBTITLE NBSMEASUREMH^ITSERVICES: Radiome... Open at page → 147 Page 147 PUBLICATIONS INTHESP250SERIESFROMTHECENTERFORRADIATIONRESEARCH SP250-1 N8SMeasurement Services: SP250-12 SpectralRadianceCalibrations J.H.Walker,R.D.Saunders, andA.T.Hattenburg SP250-2 NBSMeasurement Services: SP250-13 F... Open at page → 148 Page 148 U.S.DepartmentofCommerce NationalBureauofStandards Gaithersburg,MD20899 OfficialBusiness PenaltyforPrivateUse$300 Open at page →