WAVELENGTH SCALING OF LITHIUM-LIKE RECOMBINATION SCHEME FOR X-UV GAIN PRODUCTION A. Carillon, F. Gadi, B. GauthÉ, H. Gunnou, P. Jaglé, G. Jamlot, A. Klisnick, C. Möllr, A. Surau To cit this vrsion: A. Carillon, F. Gadi, B. GauthÉ, H. Gunnou, P. Jaglé, t al.. WAVELENGTH SCALING OF LITHIUM-LIKE RECOMBINATION SCHEME FOR X-UV GAIN PRODUCTION. Journal d Physiqu Colloqus, 1987, 48 (C9), pp.c9-375-c9-378. <10.1051/jphyscol:1987966>. <jpa- 00227384> HAL Id: jpa-00227384 https://hal.archivs-ouvrts.fr/jpa-00227384 Submittd on 1 Jan 1987 HAL is a multi-disciplinary opn accss archiv for th dposit and dissmination of scintific rsarch documnts, whthr thy ar publishd or not. Th documnts may com from taching and rsarch institutions in Franc or abroad, or from public or privat rsarch cntrs. L archiv ouvrt pluridisciplinair HAL, st dstiné au dépôt t à la diffusion d documnts scintifiqus d nivau rchrch, publiés ou non, émanant ds établissmnts d nsignmnt t d rchrch français ou étrangrs, ds laboratoirs publics ou privés.
JOURNAL DE PHYSIQUE Colloqu C9, supplmnt au n012, Tom 48, dgcmbr 1987 WAVELENGTH SCALING OF LITHIUM-LIKE RECOMBINATION SCHEME FOR X-UV PRODUCTION GAIN A. CARILLON, F. GADI, B. GAUTH~, H. GUENNOU, P. JAEGL~, G. JAMELOT, A. KLISNICK, C. MOLLER and A. SUREAU Laboratoir d Spctroscopi Atomiqu t Ioniqu, Bat. 350, Univrsit Paris-Sud, F-91405 Orsay Cdx, Franc and GILM, Ecol Polytchniqu, F-91128 Palaisau Cdx, Franc RESUME. On prsnt ds valurs d gain obtnus tant par msurs xprimntals qu par prvisions thgoriqus pour ls transitions 3d-5f, 3d-4f t 4d-5f ds ions 1ithiumoEds dans &+s plasmas produits par lasr. A la suit d'un tud dgtaillg du cas d l'ion A1 /1/ t n s fondant sur ds prgvisions obtnus par calcul pour ls ions d charg plus 6lv /32/, nous prgsntons ls prmirs rsultats xpgrimntaux c_o crnant ls ions s1 +. En particulir, un cofficint d gain d P l'ordr Q 1 cm a 6t6 msurg pour la transition 3d-5f d S XIV 2 la longuur d'ond d 65.2 A, qui st la plus court pour laqull la msur d'un gain ait jamais 1'pY)t f 81t dluf.g+ publication jusqu'8 c jour. Ds calculs concrnant ls ions K, Ca t Ti sont 6galmnt prgsnt6s. ABSTRACT. Obsrvd and prdictd valus of gain for 3d-5f, 3d-4f and 4d-5f transitions of lithium-liklof+ons in lasr-producd plasmas ar rportd. Aftr an xtnsiv study of th A1 cas /1/ and following calculatd prdict992 for highr-z ions /2/ w prsnt th first xprimntal rsu ts concrning th S ion. -3 In particular, a gain cofficint of th ordr of 1 cm has bn masurd for th 3d-5f transition of S XIV at th wavlngth of 65.2 1, which is th shortst for which th masu a gain s vr bn publishd to day. Som calculat~ons concrning th K 5~n\aq5t, and Ti1'' ions ar also prsntd. INTRODUCTION. Although no X-ray lasr dvic has yt bn achivd to day, th most rcnt progrss in this fild /3/ has mad it sur such a fasibility. As a consqunc of that, th proccupation of sarchrs is no mor only to incras th valu of th gain-lngth product thy obtain in thir xprimnts, but also to look forward for futur applications. Among ths, th intrst of biologists for shortr wavlngths comprisd btwn 23.3 and 43.5 1, in th so-calld watr-window, is now wll known. In this rang, sinc watr is rathr transparnt to radiation whil carbon is opaqu, on can hop to obtain holograms of living protins with a good contrast. That is on of th rasons why wavlngth-scaling of th diffrnt schms considrd for X-ray lasing action has bcom an incrasing proccupation. PRESENTATION. In this qgqr w shall dal with lithium-lik rcombination schm, dparting from th A1 ca: for which w hav rportd an amplification of spontanous mission at 105.7 A as arly as 1978 /4/. Indd, if on considrs ths ions in a rapidly cooling plasma, population invrsion appars btwn th lowr 3d lvl and th uppr 4f (154.6 A) and 5f lvls (105.7 1) as prdictd by calculation taking into account radiativ cascads and collisionnal transitions rats /2,5,6/. Exprimntal gain masurmnts hav bn prformd for both transitions, in th corona, i.., in a rbon 2.j th lasr-producd plasma whr lctronic dnsity N is of th ordr of 10 cm. Th wavlngth of th lasr was 1.054 pm and th pul~s duration was ithr 600 ps or 2 ns. Th lasr bam was Focusd on th surfac of a massiv targt by two crossd cylindrical lnss, providing a fairly homognous lighting along th focal lin of 1 to 2 cm long. Th flux linar dnsity on th targt was in th rang of 0.5 to 20 GW/C~. Gain G was dducd from th nhancmnt of mittd intnsity I1 with plasma lngth 1 using th rlation I orxp(g1)-1. 1. Tim-rsolvd xprimnts hav shown that amplification taks plac durxng plasma Articl publishd onlin by EDP Scincs and availabl at http://dx.doi.org/10.1051/jphyscol:1987966
C9-376 JOURNAL DE PHYSIQUE cooling aftr th top of th lasr puls. Masurd pak valus of gain-lngth product ar comprisd btwn 2 and 2.5 cm. Ths rsults hav bn accountd for by thortical calculations which hav shown that, in th cas of aluminium, gain occurs for, th 5f-3d and 4f-3d transitions in th plasma corona during th cooling and rcombination phas. Calculations ar prformd with a collisionnal-radiativ modl usd as th postprocssor of a hydrodynamical cod. Considring a highr Z lmnt as sulphur, for which th 3d-5f and 3d-4f transitions of SXIV ar situatd at 65.2 and 95.5 A, th C.R. modl has bn usd introducing various sts of dnsity and tmpratur obtaind from th hydrodynamical cod in th cas of Al. This is mad possibl by th rathr broad rang of convnint valus rvald by th cod. Th C.R. modl givs th valus of invrsion dnsity An and, sinc th xprssion of gain is givn by: G(cm -1 )=3.274 10~ 14 (An) S (M/kTi) 1/2-3 whr n is xprssd in cm, S is th lin strngth in u.a., M th atomic mass and Ti th ionic tmpratur in V, on can obtain th xpctd valu of gain in ach cas. Tabl I shows a comparison of rprsntativ rsults obtaind for Al and S. It appars that comparabl valus of gain can b obtaind with both lmnts. Al^ N(cm~ 3 ) 10^ 5 10 19 _T_iC.V) ^--.i- LMn G(cm x ) 4.08 10 W S An 4.24 10 W S^.n X(A) GCcaT 1 ) X(A) GCcm" 1 ) 5f-3d 105.7 1.4 _ 65.2 1.3 154.6 6 ~ "9574 ~2T3 ' ISA,7 S.6 95.5 3.5 334.2 1.1 206.3 3.1 334.4 1.6 206.5 4.4 TABLE I On th basis of this valuation a study of th 5f-3d transition in sulphur, at 65.2 A, has bn undrtakn. A massiv planar targt was usd and w compard intnsitis mittd by plasmas of 1 and 2 cm producd by a 1.054 um-'-lso J lasr bam with a puls duration of 2 ns. Th lm-grazing incidnc spctromtr uss a 3,600 groovs/mm grating. An O.M.A. was usd for dtction. For this first xprimnt only tim-intgratd masurmnts wr mad. An xampl of rsult is shown on Fig.l. Uppr curvs rprsnt th spctra mittd by both plasmas in th rgion of 65 A. Th strongst lin^is th Sf-^d at 65.2 A, whil th othr on on th lft sid is th 5d-3p at 64.3 A. At 65.2 A, a suddn drop is clarly visibl in th absorption curv which is rprsntd in lowr part. A simulation has bn undrtakn to invstigat th ffcts of tim-intgration on th obsrvd valu of gain as wll as thos of th xprimntal width. Th rsult of this study, as it appars in Fig.2 and 3, shows that an instant gain of about 1 cm accounts for th xprimntal obsrvations. WAVELENGTH SCALING. Whn scaling with highr Z-lmnts towards shortr wavlngths on must considr lasr intnsity, lctronic dnsity and lctronic tmpratur. In th Li-lik rcombination schm, lasr intnsity must b sufficint for crating H-lik ions. Sinc th prsnc of ths ions is conditionning th invrsion schm, if Z is th atomic numbr of an lmnt, th scaling will dpnd not on Z but on th paramtr z=z-2. So, with an lmnt Z', lt z'=z'-2, th following rlations hav to b considrd: I'. =(z'/z) 3 T lasr lasr N '= (z'/z) 7 N T '= (z'/z) 2 T
C9-377 Tim-rsolvd gain at th top of th lin dducd from a plasma modling Fig. 2 Exprimntal rsult in sulphur. Lowr part: absorption curv. Fig. 1 Tim-intgratd absorption curv a) dirctly dducd from gain in Fig.2 b) taking into account instrumntal width Fig. 3 On th basis of this scaling, dparting from sulphur, a thortical study has bn undrtakn concrning Ca, Ti and Cu /7/. Calculatd wavlngths in Angstrom of 3d-4f, 3d-5f, 4d-5f and 4f-5g transitions ar th following: 3d3/2-5f5/2 3d5/2-5f7/2 3d3/2-4f5/2 3d5/2-4f7/2 4d3/2-5f5/2 4f5/2-5g7/2 4d5/2-5f7/2 4f7/2-5g9/2 17+ Ca 39.50 39,55 57.76 57.86 124.78 124.95 124.97 125.03 _.19+ Ti 31.99 32,04 46.77 46.87 101.06 101.20 101.25 101.29 n 26+ Cu 17.54 17.59 25.64 25.74 55.41 55.50 55.59 55.59 Extrapolatd plasma paramtrs hav bn introducd into th tim-dpndnt C.R. modl. Enrgy lvls and oscillator strngths usd in th modl ar obtaind by ab initio calculations with a modifid Hartr-Fock mthod. Atomic dynamics includs radiativ cascads and lctron ion collisions. Rducd-population dnsitis N/g, whr g=2j+l is th statistical wight of th lvl, hav bn calculatd as functions of tmpratur T. This was prformd for diffrnt valus of N and in ach cas, for various valus of th paramtr X which rprsnts th proportion of H-lik to Li-lik ions. On Fig.4 ar prsntd th most charactristic rsults obtaind for both 5f-3d and 4f-3d transitions. It appars that in all cass
C9-378 JOURNAL DE PHYSIQUE significativ invrsion-ratio valus ar obtaind. Du to lack of spac, 5-4 transitions ar not prsntd hr although still strongr valus hav bn obsrvd in som cass. Thus, ths rsults dmonstrat th intrsting possibilitis offrd Li-lik ions in X-UV lasr studis. Fig. 4 CONCLUSION. Li-lik rcombination schm sms particularly appropriat for scaling towards shortr wavlngths sinc th nd in powr dnsity for plasma production is rathr modrat. An illustration of that is rprsntd in Fig.5 whr w hav plottd powr dnsitis vrsus wavlngths for th diffrnt schms proposd to-day. Anothr aspct of this study is to show,013 up th intrst of invstigating also th 4-5 transitions, particularly th 4d-5f and 4f-5g, not for shortr wavlngths, but for highr gains. 10'~- S * 0 *: 3:-lik *: Li-lik Ni-lik,, MO 0.: 0 - B 1 t a, 8 i I /'* '3.Eum Al 1 B =* i i j I i 1 1!! REFERENCES Fig. 5 1 - P. JAEGLE, G. JAMELOT, A. CARILLON, A. KLISNICK, A. SUREAU and H. GUENNOU, J.O.S.A. B, 4, 563 (1987); (Fatur dition on th Gnration of Cohrnt XUV and Soft-X-ray Radiation). 2 - H. GUENNOU, A. SUREAU, C. MOLLER, Intrnational Colloquium on X-Ray Lasrs, Aussois, Franc, 1986; Journal d physiqu, C6-351, Vol 47 (1986). /3/ - D.L. MATTHEWS t al., Phys. Rv. Ltt, 54, 110 (1985). 141 - P. JAEGLE, G. JAMELOT, A. CARILLON and C. WEHENKEL, Jpn. J. Appl. Phys. 17, 483 (1978). 5 - A. KLISNICK, H. GUENNOU and J. VIRMONT, Journal d Physiqu, 47, C6 351 (1986). /6/ - H. GUENNOU and A. SUREAU, J. Phys. B, 20, 919 (1987). /7/ - A. SUREAU, H. GUENNOU, C. MOLLER. Procdings of th I.U.A. colloquium No 102, Sptmbr 9-11 Sptmbr 1987, Bauliu s/mr, Franc.