[NWP.19] Radal Cataphorss n Hg-Ar Fluorscnt Lamp schargs at Hgh Powr nsty Y. Aura, G. A. Bonvallt, J. E. Lawlr Unv. of Wsconsn-Madson, Physcs pt.
ABSTRACT Radal cataphorss s a procss n whch th lowr onzaton potntal atoms (Hg) ar prfrntally onzd and xplld from a mult-componnt (Hg-Ar) dscharg. Ths procss s mportant at hgh powr dnsts whch occur n som typs of fluorscnt lamps (.g. th lctrodlss Endura/Ictron lamp dvlopd at Osram Sylvanc Inc.). Rcnt attmpts to rconcl xtnsv absolut masurmnts on Ictron lamp dschargs wth slf-consstnt numrcal modls wr only partally succssful [2]. Radal catphorss as wll as som othr hgh powr dnsty phnomna nd to b r-xamnd. W hav st up an axal absorpton xprmnt at 185 nm on th ground lvl Hg atoms n an opratng Ictron lamp. Th Hgh Snstvty Absorpton Spctroscopy (HSAS) faclty at th Synchrotron Radaton Cntr n Stoughton WI s usd n ths study. Th HSAS faclty provds an ntns synchrotron radaton contnuum, vry hgh spctral rsolvng powrs from a 3 m focal lngth vacuum chll spctromtr, and suprb S/N ratos from a CC dtctor array. Prlmnary rsults wll bprsntd and dscussd. [1] Supportd by th NSF amp; USHIO Inc. Exprmntal lamp provdd by OSRAM-SYLVANIA Inc. [2] J. J. Curry, G. G. Lstr, J. E. Lawlr, J. Phys. : Appl. Phys. 35, 2945 (22)
Exprmntal Lamp Exprmntal lamp has two flat HIGH QUALITY Suprasl wndows at th nd of on arm. No phosphor Ar 4Pa(3mTorr) + Lqud Hg Hg prssur s controlld by tp tmpratur. 36.8 cm INLET WINOW OUTLET WINOW SR BEAM To SPECTROMETER TIP
Th Hgh Snstvty Absorpton Spctroscopy (HSAS) faclty Th Hgh Snstvty Absorpton Spctroscopy (HSAS) faclty at th Synchrotron Radaton Cntr n Stoughton WI Lght Sourc : Synchrotron radaton (SRC) Spctromtr: Sya-Namoka + vry hgh spctral rsolvng powrs from a 3 m focal lngth vacuum chll spctromtr tctor : suprb S/N ratos from a CC dtctor array. Lght path : Vacuum or N2 flushd (Lamp Box) Sya-Namoka spctromtr Synchrotron SRC@Stoughton,WI 3 m focal lngth vacuum chll spctromtr
Poston of masurmnts Lamp s on mchancal translaton stag Masur n two dm., vrtcal and horzontal. Synchrotron Radaton (SR) gvs bam dvrgnc and cross scton (bam ~Ф1mm) UPWOR +.9 [Inchs] SR BEAM -.9 INSIE OUTSIE -.9 OWNWOR OUTLET WINOW
Spctrum Analyss (1) Problm : Establshng a rlabl zro absorpton background Whn th lamp s off, thr s stll Hg vapor whch absorbs th SR bam. If th lamp s rmovd from th optcal path, th algnmnt s changd and O2 absorpton bcoms a problm. Soluton Assum ntnsty of th SR s th sam at narly wavlngths. Background spctrum can b masurd wthout turnng off th lamp. Absorpton I Hg Hg [ SR + Lamp] = [ SR + Lamp] + 6 6 1 2 S S 1/ 2 6 Spctrum 1 λ λ P 6 1 2 sp bg P 1/ 2 [ Lamp] [ Lamp] λ λ sp bg 185nm 194.2nm Hg Hg + on Absorpton spctrum 185nm 194.2nm Background spctrum 186nm 193nm
Spctrum Analyss (2) 1.2 1.2 1 1.8.8 Transmtanc.6.4 A B Ar Transmtanc.6.4 A B Ar.2.2 2 3 4 5 6 7 8 9 1 Pxl Hg Absorpton spctrum 185nm 2 3 4 5 6 7 8 9 1 Pxl Hg + Absorpton spctrum 194.2nm
Curv of growth 6 14 5 12 Equv. Wdth [mk] 4 3 2 Equv. Wdth [mk] 1 8 6 4 1 2 2 4 6 Column nsty [ x 1 15 cm -2 ] Curv of growth @ 185nm 1 2 3 Column nsty [ x 1 11 cm -2 ] Curv of growth @ 194.2nm
Hg + Ion dnsty vs. poston cold spot tmpratur = 5C wth varous currnt Horzontal strbuton of Hg + on nsty Cold spot 5C 3A 4.5A 6A 7.7A Vrtcal strbuton of Hg + on nsty Cold spot 5C 3A 4.5A 6A 7.7A 4. 4. 3.5 3.5 Hg + on nsty [1 14 cm -2 ] 3. 2.5 2. 1.5 1. Hg + on nsty [1 14 cm -2 ] 3. 2.5 2. 1.5 1..5.5. -1 -.5.5 1 poston [nchs] Insd Outsd. -1 -.5.5 1 poston [nchs] Bottom Top
Fttng wth Bssl functon Assum cylndrcal symmtry and lowst ordr ambpolr dffuson mod Hg + on dnsty dstrbuton can b wrttn as a Bssl functon nsty [1 14 cm -2 ] 4.5 4 3.5 3 2.5 2 1.5 1 ata Bssl Functon nsty= n J ( x) = k= J ( x) k ( 1) k! Γ( k + 1) x 2 2k.5-1 -.5.5 1 stanc [nchs] UP OWN Bottom Top
Hg + Ion dnsty n vs. Lamp Currnt cold spot tmpratur = 5C wth varous currnt nsty n [1 14 cm -2 ] 4 3.5 3 2.5 2 1.5 1.5 Hg + on dnsty s almost lnar to th lamp currnt 2 4 6 8 1 Lamp Currnt [A]
ata for ffuson Equatons N px = k Hg Hg d nhg dn N = a dr N dr a 2.42r ( T, r) = NHg( T) nj R =.2956 8.69 ρk T P k kt 1/ 2 P 3/ 2 k = 2.141 1 Hg + ION dffuson coffcnt Assumpton T=1V=116K n=n Hg Nutral Hg dffuson coffcnt 21 ρk n T k 1/ 2 T R r NHgo Ambpolr Hg dffuson coffcnt a a = cold spot tmpratur [K] T >> Radus =.9 [nchs] Poston of radus [nchs] # n vapor prssur + + kt + + >> T T T
Nutral Hg dnsty vs. poston cold spot tmpratur = 5C wth varous currnt Horzontal strbuton of Hg nsty Cold spot 5C Vrtcal strbuton of Hg nsty Cold spot 5C 3A 4.5A 6A 7.7A 3A 4.5A 6A 7.7A 2.5 2.5 2. 2. Hg nsty [1 16 cm -2 ] 1.5 1. Hg nsty [1 16 cm -2 ] 1.5 1..5.5. -1 -.5.5 1 poston [nchs] Insd Outsd. -1 -.5.5 1 poston [nchs] Bottom Top
Comparson wth Calculaton usng dffuson quatons Horzontal strbuton of Hg nsty Cold spot 5C Vrtcal strbuton of Hg nsty Cold spot 5C 2.2 2. 3A 4.5A 6A 7.7A 3A-smulaton 4.5A-smulaton 6A-smulaton 7.7A-smulaton 2.2 2. 3A 4.5A 6A 7.7A 3A-smulaton 4.5A-smulaton 6A-smulaton 7.7A-smulaton Hg nsty [1 16 cm -2 ] 1.8 1.6 1.4 1.2 Hg nsty [1 16 cm -2 ] 1.8 1.6 1.4 1.2 1. 1..8-1 -.5.5 1 poston [nchs] Insd Outsd.8-1 -.5.5 1 poston [nchs] Bottom Top
Concluson nsty dstrbuton can b masurd by usng th Hgh Snstvty Absorpton Spctroscopy (HSAS) faclty Hg and Hg + on dnsty dstrbuton shows thr s radal cataphorss n ICETRON lamps. Hg dnsty dstrbuton s consstd wth Hg+ on dstrbuton and dffuson quatons.
Futur work ffrnt cold spot tmpratur analyss Corrcton of modl for lamp shap Incluson of ffcts from gas hatng Spcal thanks th NSF; OSRAM-SYLVANIA Inc. ; USHIO Inc. r. P. Moskowtz, OSI r. J. J. Curry, NIST