- Email: [email protected]
Absorption spectroscopy of radiatively-heated low-Z foils
J Qum
Pergnmon
Spec~rosc
Radror
00224073(93)EOIM-T
ABSORPTION SPECTROSCOPY RADIATIVELY-HEATED LOW-Z J F SEELY,t U FELDMAN.tC M
Tromler Vol 51 No I ? pp 349-355 1994 Elsevw Smnce Ltd Primed in Great Brcm MI??-4073 94 $6 00 + 0 00
OF FOILS
B A HAMMEL.~ C A BACK,$E HSIEH,~ and R W LEES
BROWN,7
tE 0 Hulburt Center for Space Research Naval Research Laboratory 4555 Overlook Avenue S W Washmgton. DC 20375-5352 and SLawrenee LIbermore NatIonal Laboratory Llbermore CA 94550 USA
Abstract-Hugh-resolution absorption spectra of radlatlvely-heated low-Z foils (CH and BN) have been recorded at the Nova II laser faclhty by a grazmg-mcldence spectrograph Using a cahbrauon curve for Kodak 101 photographtc plates, the plate density was comerted to relative intensity transmitted by the foil Absorption spectra are presented for the elements B, C, and N The absorption features near the nickel L edge In the wavelength region I I-15 A are also presented
INTRODUCTION
The absorption spectra of radlatlvely-heated CH and BN fads have been studied at the Nova II laser faclhty usmg a high-resolution grazmg-Incidence spectrograph The foils were indirectly heated and backht by the x-ray contmua from nearby gold fads The expenmental details and prehmmary spectra were discussed m Ref I In this paper we present a cahbratlon of the Kodak IO1 photographlc plates that were used to record the spectra, the derivation of the relative mtensltles transmltted by the foils. and the absorption spectra of CH and BN foils PLATE
CALIBRATION
The spectra were recorded by a 3 m grazing-mcldence spectrograph that was described m Ref The radiation from the target was focused onto the entrance slit of the spectrograph by a cyhndrlcal gold-coated mirror The radlatlon was incident on the mirror at a grazing angle of 2 The linear Image formed by the mirror was shghtly tilted with respect to the entrance slit. and this resulted m the spatial resolutron of the spectrum m one dlmenslon The radiation was then Incident on a gold-coated gratmg at a grazmg angle of 2’ The gratmg had I200 grooves/mm and a blaze angle of 2-35’ The spectra were recorded on Kodak IO1 plates that were bent to conform to the Rowland circle The plate cahbratlon was determmed by recordmg the spectra transmltted through a step wedge filter The filter covered half of the entrance slit so that unfiltered and filtered spectra were simultaneously recorded on the same laser shot The step wedge filter was composed of I, 2, 4. 6, and 8 thicknesses of parylene-D foil, where the thickness of a single foil was 1300 A The mtenslty of the radiation reachmg the emulsion was the product of the intensity emltted by the plasma, the reflectance of the gold-coated mirror, the transmittance of the filter, the efficiency of the gold-coated gratmg, and the transmittance of the thm emulsion gelatm Each of these quantities was dependent on the wavelength of the radlatlon The target was a gold disk Irradiated at low Intensity, and previous characterlzatlon studies indicated that the emtsston was approxtmately a black-body dlstnbutlon with temperature m the range 100-200 eV The grazing-Incidence reflectance of the mirror was calculated using the optlcal constants of gold listed m Ref 3 The transmittance of the parylene-D (CgH6C12) filters were calculated usmg the optlcal constant of carbon, oxygen, and chlorme derived from Ref 4 and assuming a density of I 42 g/cm’ The gratmg efficiency was calculated using scalar theory Durmg previous experiments using a newly-coated 2
349
350
J F SEELY et al
mirror and grating, the oxygen and carbon K absorption edges at wavelengths of 23 3 and 43 5 A, respectlvelq, were observed These absorption features were attributed prlmarlly to the absorption of the thm emulsion gelatin The thickness and composltlon of this gelatin was inferred by comparing the observed relative depths of the oxygen and carbon K absorption features with the calculated grazing-Incidence transmittance of a gelatm composed of variable oxygen and carbon areal densltles It was Inferred that the abundances of oxygen and carbon In the gelatin were approximately equal, and the areal densities of oxygen and carbon were I x IO“ atomsicm’ The calculations were performed at IO wavelengths from 25 to 66 8, These wavelengths were chosen to fall m the regions between the oxygen and carbon absorption features In Fig I, curve (a) IS the Intensity of a 2OOeV black-body dlstnbutlon normalized to maximum Intensity of 100 at 25 A Curve (b) IS the product of the black-body dlstnbutlon and the grazing-Incidence reflectance of the gold-coated mirror Curve (c) IS the product of curve (b) and the gratmg efficiency Cur\e (d) IS the product of cur\e (c) and the grazing-Incidence transmittance of the gelatin Curve (d) represents the relative Intensltl of the unfiltered radiation Incident on the emulsion as a function of wavelength The photographic density was measured at the IO wavelengths and m the unfiltered and filtered regions of the plate Figure 2(a) IS a plot of the measured photographic densities and the relative lntensltles determined by multIplyIng curve (d) In Fig 1 by the filter transmittance Each curve m Fig 2(a) relates the photographic density and the relative intensity at a particular wavelength The data points were fitted to the expresslon’
D Ldl=D where the fog correctlon
(1)
Has” D,,, = &,,a, - &,
The assumed maximum
rlIp +D md’L(I-e-‘bl)
(D,,,
- D,,,
): (Qm,, - D,,, )
(2)
density was D,,, = 2, and the best least squares fit was determined
by
03
02
01 100 L !Z Zl 2 0
03 10
02
> Iv, z k z -
01 1
20
50
60
WAVELENGTH
30
40
(A)
70
FIN I (a) The mtenslty of a 200 eV black-body dlstrlbutlon normahzed IO maxlmum Intensity of 100 at 25A (b) The product of the black-body dlstrlbutlon and the grazmg-mcldence reflectance of the gold-coated mirror (c) The product of curve (b) and the grating efficiency (d) The product of curve (c) and the granng-mcldence transmittance of the gelatin
001
01 INTENSITY
1 (at-b.
10 units)
Fig 2 The photographlc denswes (D,,,) versus the relative mtensltles In (a) a straight lrne connects the data pomts for each of the IO waLelengths from 25 to 66 A In (b). the data points are mdlcated bj the square symbols and the smooth cur\e IS the fitted sahbratlon curve
Absorption 04
spectroscopy
of radlatwely-heated
351
fods
I
I
I
low-Z
(a)
16
03
02
01 E f ii $
(b)
z 03
02
01
0 25
30
WAVELENGTH FIN
3 The absorptance
45
40
35
(A)
of (a) a I m CH fool1and (b) a lammar fo’ollcomposed of 1000 A CH and 1000 # CH The transItIons are ldentdied m Table I
200 A mckel
varying the parameter I, The fitted curve IS shown m Fig 2(b). and this curve represents the wavelength-independent plate cahbratlon curve This cahbratlon was applied to other plates that were developed m the same manner as the cahbratlon plate Kodak 101 plates are known to be quite sensitive to small changes m developmg conditions and to storage and handling condltlons Thus the cahbratlon determined for one plate may not be exactly applicable to other plates Therefore, the accuracy of the relative Intensities of two spectral features derived from the curve of Fig 2(b) IS estimated to be approx 30% for densities greater than 0 I
ABSORPTION
SPECTRA
For the low-Z foils considered here, the strongest absorption occurs at the wavelengths corresponding to the ground-state transItIons of the H-hke and He-hke ions Absorption may also occur near the transition senes hmlts The absorption and scattenng of radIanon m the wavelength regions between the ground-state transltlons and above the senes hmlts IS weak That IS, the radiation from the backhghter with wavelengths near a ground-state transltlon IS strongly absorbed, and the radiation with wavelengths m the regions between the ground-state transltlons and above the series limits IS transmitted by the foil with little attenuation Under these condltlons.
3.52
J F
SELY
et al
the transmtttance of the foil may be estimated by dtvldtng the recorded spectrum by a spectrum dertved from the ‘unattenuated” radtatton The absorptance of the foil IS equal to thts ratto subtracted from unity The self-emlsston of the low-Z foil IS assumed to be neghgtble compared to the emtsston from the gold backlighter for1 The plate cahbratton curve was used to convert the photographtc density of the observed and “unattenuated” spectra to relative intensity Errors m the cahbratlon curve tend to cancel when the mtensmes are dtvtded to obtain the transmittance of the foil Shown n-t Ftg 3(a) IS the absorptance of a CH for1 that was I pm thick A 0 25 pm gold coating was deposued on the back side of the CH foil A Nova beam. with 4 kJ of 0 53 pm light tn a I nsec pulse and focused to a 2 mm dta spot, was Incident on the gold stde The grazing-mctdence spectrograph viewed the front side of the CH foil Prevtous experiments on free-standing gold foils Indicated that the gold foil dtd not burn through during the laser pulse, and the CH for1 was therefore heated mdtrectly. prlmanly by the soft x-ray contmuum from the gold fotl The transtttons identified In Ftg 3 are listed In Table I The wavelength shown wtth three decimals are from Ref 7. and the wavelengths shown with two dectmals are presently measured Figure 3(b) shows the absorptance of a lamtnar foil composed of 1000 8, CH. 200 A mckel. dnd 1000 8, CH This foil was held by a triangular support (of the type described In Ref I) that also held two gold heater and backlighter foils The heater and backhghter foils were 3 and IO mm from the CH/NI/CH foil respectively The spectrograph viewed the backlrghter foil through the CH;‘Nl,‘CH foil. and the heater foil was obscured from vteu The backhghter and heater foils Here Irradiated by two Nova beams. and the backltghter beam *as delayed by I nsec with respect to the heater beam The CHlNlCH foil was therefore radtattvely heated by the heater foil and after I nsec was tllummated by the backlrghter foil The spectrograph recorded the soft x-ray conttnuum from the backlighter fotl that was transmitted by the radrattvely-heated CH,Nl,CH fotl The transttlons from the He-like C V ground state Is ’ ‘S,j-lsrrp ‘P, are quote strongly absorbed In both spectra shown rn Ftg 3 The translttons from the Lt-hke C IV configurattons Is’2s and lr’2p are more prominent In the spectrum of Ftg 3(b). while the C VI transmons” Is ‘S-np ‘P were more prominent m Ftg 3(a) This tmphes that the abundance of the more highly charged carbon tons was larger In the for1 that was m phystcal contact with the gold heating foil [Fig 3(a)] The C V dlelectromc satellite translttons from the 1~2s and 1x2~ conligurattons are present rn absorptton m Ftg 3(a) These configuratlons have excttatton energtes of 300 eV, while the electron temperature of the foil IS believed to be less than 50eV ’ The Is21 and ls2p configurations are probably populated primarily by absorptton of the C V Is’ IS,-ls2p ‘P, resonance transttron followed by redtstnbutton of the populatton among the excited levels, although these highly-exctted
Tdble I No
Ion
2 3 4
CVI c VI N VI C V
-
CL’
:
c V VI c v c V CL Cl c IV c IV C IV c IV c v c v c IV c IV c IV C IV Cl
I
7
8 9 IO II I’ I3 I4 I5 I6 I7 I8 I9 20 21 22
c
Transttron
Is’S,,4p~P,,,, Is -s, _-3p P, -1.’ Is: IS,-ls2p ‘P, Is’ ‘.S,-ls6p ‘P, Is .’ ‘.s,-IsSp ‘P, Is-’ ‘.s,-lS4P ‘P, Is ‘S, ;-2p if, :; z IS?> ‘S,-2SZD ‘P Is2p li.,-?pi ‘P,’ Is2p ‘P,-2p- ‘D. Is ’ ‘.s,-ls3p ‘P, Is-‘?p~P-l;2p(“P)3p ‘P Is’b JS-lsZs(‘S)3p ‘P Is?p ‘P-ls2p(‘P)3p ‘D Is% ?P-lslo(‘P )30 . . ‘P 11: iP,-ls2p ‘P, Is- ‘.s,-lr2p ‘P, ls’2p >P-ls2p? -‘s IS% ?S-Ids(‘S)2p :P ls?2p :P-ls2p: !P Ir’2p :P-ls?p’ :D edae
Wavelenp;th (A) 26 990 28 466 28 787 32 400 32 754 33 426 33 736 34 53 34 59 34 70 1-l 973 36 68 36 86 36 99 37 13 40 268 40731 40 74 40 90 41 34 41 52 43 54
Absorption
spectroscopy
of radIatIveI)-heated
low-Z
353
fo11s
02
12
"11
WAVELENGTH Fig
I
The absorptance
5 The absorptance
of a 0 18 pm
15
(A)
near the nrckel L absorption
WAVELENGTH Fig
14
13
edges
(A)
BN fool m the wavelength ldentlfied m Table ?
regon
20-35 A
The transltlons
are
configuratlons may also be populated by super-hot electrons The relative mtensures of the dtelectromc satelhte transmons may be useful as a densny dtagnosttc (cf Refs 9 and 10) Ftgure 4 shows the absorptance of the CH/NI/CH foil In the wavelength regron near the nickel L abso tlon edge The cold nickel Ll, L,, , and L,,, edges have wavelengths of I2 267, 14 135, and 14 448 r , respectively ” These cold edges result from the excttatton of a 2+, 2p, 2r or 2p,,, electron As shown m Frg 4, absorption bands are observed Just below the L,, and L,,, edges and probably result from absorption transltlons of the type Is ‘2s ‘2~ 63s ‘3~ 63d’-ls ‘2s *2p 53s‘3~ 63dk+ ',where the bands represent different values of k c IO Modeling of the band structure using the HULLAC code IS m progress From these results may be inferred the ground state abundances of the nickel Ions and perhaps the temperature and density of the nickel plasma Shown m Figs 5 and 6 IS the absorptance of a BN fotl that was 0 18 pm thrck This for1 was
J F SELI
et al
50
55
60
65
WAVELENGTH (A) FIN
6
The absorptance
ot d 0 18pm
BN foil m the adbelength ldentltied m Table 2
regmn
35-70A
The transmons
are
mounted on a triangular support as described ahobe The tdentlfied transtttons are hsted m Table 2 The cold oxygen and carbon K edges were observed at 23 30 and 43 54 A. respectively. and the cold nitrogen and boron A’ edges at 30 99 dnd 66 29 A were not observed The cold oxygen and carbon K absorption edges observed m the BN data (and also m the CH data) resulted from the emulsion gelatin The He-like N VI and B IV transitions from the IS’ ground states were strongly absorbed. and LI-like N V and B III transttlons from the Is ‘2~ configuration were also absorbed The H-like B V transItIons were observed. and the H-like N VII transitions were not observed which Implies that the abundance of the N VII ground state was low It IS interesting to note that the N VI and B IV Is’ ‘!&,-1.~2~ ‘P, absorption features are comparable to the correspondmg Is-’ IS,,-1.73~ ‘P, absorptlon features In Figs 5 and 6 DISCUSSION
The spectroscopic analysis of the absorptance of radtattvely-heated fotls can be used to determine the relative abundances of the ground state tons and to estimate the plasma temperature and density The deterrmnatlon of these quantities depends on the use of non-LTE radiation transport Table
No I , ; 1 5 b 7
8 9 IO II I’ I? I-l I5 16
Ion 0 I N 11 N VI N VI N V N 1 B V B\ C I B V B IV B IV B IV B IV B 111 B III
2
Trans1tu.m edge I>’ IS,,-ls4p ‘P, 15: IS,,-ls3p ‘P, Is- ‘S,-L?p ‘P, IY-2p :P-ls2p’ ‘P 11-2~ 2P-I~2pp’ -‘D Is is, ,--lp -P, 3, I5 -S, -3p -P, 2) 7 edge Is ‘S, ,-2p -P, z) _ Is? IS,-ls5p ‘P, Is’ IS,,-Is+ ‘P, Is: IS,,-1~3~ ‘P, Is: IS,,-1x2~ ‘P, Is-Q -P-ls2p’ P Is ‘20 ‘P-ls2n’ -‘D
WaLelength 23 30 23 771 24 898 28 787 29 43 29 57 38 871 40 996 43 54 48 588 49 455 50 435 52 685 60314 6221 62 49
(A)
Absorption spectroscop) c&es
H$n
s~ec~rb~ resc?nn>on
IOIIS (such as the dlelectronlc
IS necessary
satelhte
of radlatnell-heated
low-Z fads
355
ine c%&~Y -yzwxb ‘1Tansnlnns ci? -Ine’>ow-1 and the band structure of the higher-Z tons such
ICI resc+e
transitions)
as mckel REFERENCES
I B A Hammel
Z 3 4 5 ch
7 8 9 IO II
D R Kama R Doyas, R W Lee. C A Iglaslas. J F Seely. U Feldman. and C M Brown, m Radlarlre Properrws of Hot Dense Matrer, W Goldstem. C Hooper. J Gauthler. J Seely. and R Lee eds , World Sclentlfic. Smgapore (1991) 1J’ E &tiring, J‘ ?i cnakr\hooa: c Ih’ &own. 6 fit&an, J' F Se+, f J* Marshl: and 181'If Richardson, Appl Opt 27, 2762 ( 1988) E D Pahk. Hundbooh oj Oprrcal Constanrs ol Sofrds, Academic Press Orlando, FL (1985) B L Henke. J C Davis E M Gulhkson, and R C C Perera Lawrence Berkeley Laboratory Report LBL-26259 (1988) B Z Herd<. F G FUJIw&X &f rZ &%IV~ C H ZhiiTlOE bd ht A PdiiE~ .t’O.FA BZ, 823 (l\f83) w c MJh 44s Pboln-Bu)) 16, 3 J19-0, R C Kelly J- r3ils c’ifem &f u”ara io; suppl’ no I’ t’iYX1’) E Jannrtrr P N~colosr and G Tondrljo Plr,c Stqnm 4I. 458 $1990) U Feldman and L Cohen Asrrophbs J 158, L169 (1969) J F Seely, R H Dixon and R C Elton. Ph~s Rev A 23, 1437 (1981) J A Bearden. m CRC Handbook gf’C71em~r~ urtd Phstcr R C Weast and M J Astie ed . CRC Press Boca Raton. FL (1982)
Pergnmon
Spec~rosc
Radror
00224073(93)EOIM-T
ABSORPTION SPECTROSCOPY RADIATIVELY-HEATED LOW-Z J F SEELY,t U FELDMAN.tC M
Tromler Vol 51 No I ? pp 349-355 1994 Elsevw Smnce Ltd Primed in Great Brcm MI??-4073 94 $6 00 + 0 00
OF FOILS
B A HAMMEL.~ C A BACK,$E HSIEH,~ and R W LEES
BROWN,7
tE 0 Hulburt Center for Space Research Naval Research Laboratory 4555 Overlook Avenue S W Washmgton. DC 20375-5352 and SLawrenee LIbermore NatIonal Laboratory Llbermore CA 94550 USA
Abstract-Hugh-resolution absorption spectra of radlatlvely-heated low-Z foils (CH and BN) have been recorded at the Nova II laser faclhty by a grazmg-mcldence spectrograph Using a cahbrauon curve for Kodak 101 photographtc plates, the plate density was comerted to relative intensity transmitted by the foil Absorption spectra are presented for the elements B, C, and N The absorption features near the nickel L edge In the wavelength region I I-15 A are also presented
INTRODUCTION
The absorption spectra of radlatlvely-heated CH and BN fads have been studied at the Nova II laser faclhty usmg a high-resolution grazmg-Incidence spectrograph The foils were indirectly heated and backht by the x-ray contmua from nearby gold fads The expenmental details and prehmmary spectra were discussed m Ref I In this paper we present a cahbratlon of the Kodak IO1 photographlc plates that were used to record the spectra, the derivation of the relative mtensltles transmltted by the foils. and the absorption spectra of CH and BN foils PLATE
CALIBRATION
The spectra were recorded by a 3 m grazing-mcldence spectrograph that was described m Ref The radiation from the target was focused onto the entrance slit of the spectrograph by a cyhndrlcal gold-coated mirror The radlatlon was incident on the mirror at a grazing angle of 2 The linear Image formed by the mirror was shghtly tilted with respect to the entrance slit. and this resulted m the spatial resolutron of the spectrum m one dlmenslon The radiation was then Incident on a gold-coated gratmg at a grazmg angle of 2’ The gratmg had I200 grooves/mm and a blaze angle of 2-35’ The spectra were recorded on Kodak IO1 plates that were bent to conform to the Rowland circle The plate cahbratlon was determmed by recordmg the spectra transmltted through a step wedge filter The filter covered half of the entrance slit so that unfiltered and filtered spectra were simultaneously recorded on the same laser shot The step wedge filter was composed of I, 2, 4. 6, and 8 thicknesses of parylene-D foil, where the thickness of a single foil was 1300 A The mtenslty of the radiation reachmg the emulsion was the product of the intensity emltted by the plasma, the reflectance of the gold-coated mirror, the transmittance of the filter, the efficiency of the gold-coated gratmg, and the transmittance of the thm emulsion gelatm Each of these quantities was dependent on the wavelength of the radlatlon The target was a gold disk Irradiated at low Intensity, and previous characterlzatlon studies indicated that the emtsston was approxtmately a black-body dlstnbutlon with temperature m the range 100-200 eV The grazing-Incidence reflectance of the mirror was calculated using the optlcal constants of gold listed m Ref 3 The transmittance of the parylene-D (CgH6C12) filters were calculated usmg the optlcal constant of carbon, oxygen, and chlorme derived from Ref 4 and assuming a density of I 42 g/cm’ The gratmg efficiency was calculated using scalar theory Durmg previous experiments using a newly-coated 2
349
350
J F SEELY et al
mirror and grating, the oxygen and carbon K absorption edges at wavelengths of 23 3 and 43 5 A, respectlvelq, were observed These absorption features were attributed prlmarlly to the absorption of the thm emulsion gelatin The thickness and composltlon of this gelatin was inferred by comparing the observed relative depths of the oxygen and carbon K absorption features with the calculated grazing-Incidence transmittance of a gelatm composed of variable oxygen and carbon areal densltles It was Inferred that the abundances of oxygen and carbon In the gelatin were approximately equal, and the areal densities of oxygen and carbon were I x IO“ atomsicm’ The calculations were performed at IO wavelengths from 25 to 66 8, These wavelengths were chosen to fall m the regions between the oxygen and carbon absorption features In Fig I, curve (a) IS the Intensity of a 2OOeV black-body dlstnbutlon normalized to maximum Intensity of 100 at 25 A Curve (b) IS the product of the black-body dlstnbutlon and the grazing-Incidence reflectance of the gold-coated mirror Curve (c) IS the product of curve (b) and the gratmg efficiency Cur\e (d) IS the product of cur\e (c) and the grazing-Incidence transmittance of the gelatin Curve (d) represents the relative Intensltl of the unfiltered radiation Incident on the emulsion as a function of wavelength The photographic density was measured at the IO wavelengths and m the unfiltered and filtered regions of the plate Figure 2(a) IS a plot of the measured photographic densities and the relative lntensltles determined by multIplyIng curve (d) In Fig 1 by the filter transmittance Each curve m Fig 2(a) relates the photographic density and the relative intensity at a particular wavelength The data points were fitted to the expresslon’
D Ldl=D where the fog correctlon
(1)
Has” D,,, = &,,a, - &,
The assumed maximum
rlIp +D md’L(I-e-‘bl)
(D,,,
- D,,,
): (Qm,, - D,,, )
(2)
density was D,,, = 2, and the best least squares fit was determined
by
03
02
01 100 L !Z Zl 2 0
03 10
02
> Iv, z k z -
01 1
20
50
60
WAVELENGTH
30
40
(A)
70
FIN I (a) The mtenslty of a 200 eV black-body dlstrlbutlon normahzed IO maxlmum Intensity of 100 at 25A (b) The product of the black-body dlstrlbutlon and the grazmg-mcldence reflectance of the gold-coated mirror (c) The product of curve (b) and the grating efficiency (d) The product of curve (c) and the granng-mcldence transmittance of the gelatin
001
01 INTENSITY
1 (at-b.
10 units)
Fig 2 The photographlc denswes (D,,,) versus the relative mtensltles In (a) a straight lrne connects the data pomts for each of the IO waLelengths from 25 to 66 A In (b). the data points are mdlcated bj the square symbols and the smooth cur\e IS the fitted sahbratlon curve
Absorption 04
spectroscopy
of radlatwely-heated
351
fods
I
I
I
low-Z
(a)
16
03
02
01 E f ii $
(b)
z 03
02
01
0 25
30
WAVELENGTH FIN
3 The absorptance
45
40
35
(A)
of (a) a I m CH fool1and (b) a lammar fo’ollcomposed of 1000 A CH and 1000 # CH The transItIons are ldentdied m Table I
200 A mckel
varying the parameter I, The fitted curve IS shown m Fig 2(b). and this curve represents the wavelength-independent plate cahbratlon curve This cahbratlon was applied to other plates that were developed m the same manner as the cahbratlon plate Kodak 101 plates are known to be quite sensitive to small changes m developmg conditions and to storage and handling condltlons Thus the cahbratlon determined for one plate may not be exactly applicable to other plates Therefore, the accuracy of the relative Intensities of two spectral features derived from the curve of Fig 2(b) IS estimated to be approx 30% for densities greater than 0 I
ABSORPTION
SPECTRA
For the low-Z foils considered here, the strongest absorption occurs at the wavelengths corresponding to the ground-state transItIons of the H-hke and He-hke ions Absorption may also occur near the transition senes hmlts The absorption and scattenng of radIanon m the wavelength regions between the ground-state transltlons and above the senes hmlts IS weak That IS, the radiation from the backhghter with wavelengths near a ground-state transltlon IS strongly absorbed, and the radiation with wavelengths m the regions between the ground-state transltlons and above the series limits IS transmitted by the foil with little attenuation Under these condltlons.
3.52
J F
SELY
et al
the transmtttance of the foil may be estimated by dtvldtng the recorded spectrum by a spectrum dertved from the ‘unattenuated” radtatton The absorptance of the foil IS equal to thts ratto subtracted from unity The self-emlsston of the low-Z foil IS assumed to be neghgtble compared to the emtsston from the gold backlighter for1 The plate cahbratton curve was used to convert the photographtc density of the observed and “unattenuated” spectra to relative intensity Errors m the cahbratlon curve tend to cancel when the mtensmes are dtvtded to obtain the transmittance of the foil Shown n-t Ftg 3(a) IS the absorptance of a CH for1 that was I pm thick A 0 25 pm gold coating was deposued on the back side of the CH foil A Nova beam. with 4 kJ of 0 53 pm light tn a I nsec pulse and focused to a 2 mm dta spot, was Incident on the gold stde The grazing-mctdence spectrograph viewed the front side of the CH foil Prevtous experiments on free-standing gold foils Indicated that the gold foil dtd not burn through during the laser pulse, and the CH for1 was therefore heated mdtrectly. prlmanly by the soft x-ray contmuum from the gold fotl The transtttons identified In Ftg 3 are listed In Table I The wavelength shown wtth three decimals are from Ref 7. and the wavelengths shown with two dectmals are presently measured Figure 3(b) shows the absorptance of a lamtnar foil composed of 1000 8, CH. 200 A mckel. dnd 1000 8, CH This foil was held by a triangular support (of the type described In Ref I) that also held two gold heater and backlighter foils The heater and backhghter foils were 3 and IO mm from the CH/NI/CH foil respectively The spectrograph viewed the backlrghter foil through the CH;‘Nl,‘CH foil. and the heater foil was obscured from vteu The backhghter and heater foils Here Irradiated by two Nova beams. and the backltghter beam *as delayed by I nsec with respect to the heater beam The CHlNlCH foil was therefore radtattvely heated by the heater foil and after I nsec was tllummated by the backlrghter foil The spectrograph recorded the soft x-ray conttnuum from the backlighter fotl that was transmitted by the radrattvely-heated CH,Nl,CH fotl The transttlons from the He-like C V ground state Is ’ ‘S,j-lsrrp ‘P, are quote strongly absorbed In both spectra shown rn Ftg 3 The translttons from the Lt-hke C IV configurattons Is’2s and lr’2p are more prominent In the spectrum of Ftg 3(b). while the C VI transmons” Is ‘S-np ‘P were more prominent m Ftg 3(a) This tmphes that the abundance of the more highly charged carbon tons was larger In the for1 that was m phystcal contact with the gold heating foil [Fig 3(a)] The C V dlelectromc satellite translttons from the 1~2s and 1x2~ conligurattons are present rn absorptton m Ftg 3(a) These configuratlons have excttatton energtes of 300 eV, while the electron temperature of the foil IS believed to be less than 50eV ’ The Is21 and ls2p configurations are probably populated primarily by absorptton of the C V Is’ IS,-ls2p ‘P, resonance transttron followed by redtstnbutton of the populatton among the excited levels, although these highly-exctted
Tdble I No
Ion
2 3 4
CVI c VI N VI C V
-
CL’
:
c V VI c v c V CL Cl c IV c IV C IV c IV c v c v c IV c IV c IV C IV Cl
I
7
8 9 IO II I’ I3 I4 I5 I6 I7 I8 I9 20 21 22
c
Transttron
Is’S,,4p~P,,,, Is -s, _-3p P, -1.’ Is: IS,-ls2p ‘P, Is’ ‘.S,-ls6p ‘P, Is .’ ‘.s,-IsSp ‘P, Is-’ ‘.s,-lS4P ‘P, Is ‘S, ;-2p if, :; z IS?> ‘S,-2SZD ‘P Is2p li.,-?pi ‘P,’ Is2p ‘P,-2p- ‘D. Is ’ ‘.s,-ls3p ‘P, Is-‘?p~P-l;2p(“P)3p ‘P Is’b JS-lsZs(‘S)3p ‘P Is?p ‘P-ls2p(‘P)3p ‘D Is% ?P-lslo(‘P )30 . . ‘P 11: iP,-ls2p ‘P, Is- ‘.s,-lr2p ‘P, ls’2p >P-ls2p? -‘s IS% ?S-Ids(‘S)2p :P ls?2p :P-ls2p: !P Ir’2p :P-ls?p’ :D edae
Wavelenp;th (A) 26 990 28 466 28 787 32 400 32 754 33 426 33 736 34 53 34 59 34 70 1-l 973 36 68 36 86 36 99 37 13 40 268 40731 40 74 40 90 41 34 41 52 43 54
Absorption
spectroscopy
of radIatIveI)-heated
low-Z
353
fo11s
02
12
"11
WAVELENGTH Fig
I
The absorptance
5 The absorptance
of a 0 18 pm
15
(A)
near the nrckel L absorption
WAVELENGTH Fig
14
13
edges
(A)
BN fool m the wavelength ldentlfied m Table ?
regon
20-35 A
The transltlons
are
configuratlons may also be populated by super-hot electrons The relative mtensures of the dtelectromc satelhte transmons may be useful as a densny dtagnosttc (cf Refs 9 and 10) Ftgure 4 shows the absorptance of the CH/NI/CH foil In the wavelength regron near the nickel L abso tlon edge The cold nickel Ll, L,, , and L,,, edges have wavelengths of I2 267, 14 135, and 14 448 r , respectively ” These cold edges result from the excttatton of a 2+, 2p, 2r or 2p,,, electron As shown m Frg 4, absorption bands are observed Just below the L,, and L,,, edges and probably result from absorption transltlons of the type Is ‘2s ‘2~ 63s ‘3~ 63d’-ls ‘2s *2p 53s‘3~ 63dk+ ',where the bands represent different values of k c IO Modeling of the band structure using the HULLAC code IS m progress From these results may be inferred the ground state abundances of the nickel Ions and perhaps the temperature and density of the nickel plasma Shown m Figs 5 and 6 IS the absorptance of a BN fotl that was 0 18 pm thrck This for1 was
J F SELI
et al
50
55
60
65
WAVELENGTH (A) FIN
6
The absorptance
ot d 0 18pm
BN foil m the adbelength ldentltied m Table 2
regmn
35-70A
The transmons
are
mounted on a triangular support as described ahobe The tdentlfied transtttons are hsted m Table 2 The cold oxygen and carbon K edges were observed at 23 30 and 43 54 A. respectively. and the cold nitrogen and boron A’ edges at 30 99 dnd 66 29 A were not observed The cold oxygen and carbon K absorption edges observed m the BN data (and also m the CH data) resulted from the emulsion gelatin The He-like N VI and B IV transitions from the IS’ ground states were strongly absorbed. and LI-like N V and B III transttlons from the Is ‘2~ configuration were also absorbed The H-like B V transItIons were observed. and the H-like N VII transitions were not observed which Implies that the abundance of the N VII ground state was low It IS interesting to note that the N VI and B IV Is’ ‘!&,-1.~2~ ‘P, absorption features are comparable to the correspondmg Is-’ IS,,-1.73~ ‘P, absorptlon features In Figs 5 and 6 DISCUSSION
The spectroscopic analysis of the absorptance of radtattvely-heated fotls can be used to determine the relative abundances of the ground state tons and to estimate the plasma temperature and density The deterrmnatlon of these quantities depends on the use of non-LTE radiation transport Table
No I , ; 1 5 b 7
8 9 IO II I’ I? I-l I5 16
Ion 0 I N 11 N VI N VI N V N 1 B V B\ C I B V B IV B IV B IV B IV B 111 B III
2
Trans1tu.m edge I>’ IS,,-ls4p ‘P, 15: IS,,-ls3p ‘P, Is- ‘S,-L?p ‘P, IY-2p :P-ls2p’ ‘P 11-2~ 2P-I~2pp’ -‘D Is is, ,--lp -P, 3, I5 -S, -3p -P, 2) 7 edge Is ‘S, ,-2p -P, z) _ Is? IS,-ls5p ‘P, Is’ IS,,-Is+ ‘P, Is: IS,,-1~3~ ‘P, Is: IS,,-1x2~ ‘P, Is-Q -P-ls2p’ P Is ‘20 ‘P-ls2n’ -‘D
WaLelength 23 30 23 771 24 898 28 787 29 43 29 57 38 871 40 996 43 54 48 588 49 455 50 435 52 685 60314 6221 62 49
(A)
Absorption spectroscop) c&es
H$n
s~ec~rb~ resc?nn>on
IOIIS (such as the dlelectronlc
IS necessary
satelhte
of radlatnell-heated
low-Z fads
355
ine c%&~Y -yzwxb ‘1Tansnlnns ci? -Ine’>ow-1 and the band structure of the higher-Z tons such
ICI resc+e
transitions)
as mckel REFERENCES
I B A Hammel
Z 3 4 5 ch
7 8 9 IO II
D R Kama R Doyas, R W Lee. C A Iglaslas. J F Seely. U Feldman. and C M Brown, m Radlarlre Properrws of Hot Dense Matrer, W Goldstem. C Hooper. J Gauthler. J Seely. and R Lee eds , World Sclentlfic. Smgapore (1991) 1J’ E &tiring, J‘ ?i cnakr\hooa: c Ih’ &own. 6 fit&an, J' F Se+, f J* Marshl: and 181'If Richardson, Appl Opt 27, 2762 ( 1988) E D Pahk. Hundbooh oj Oprrcal Constanrs ol Sofrds, Academic Press Orlando, FL (1985) B L Henke. J C Davis E M Gulhkson, and R C C Perera Lawrence Berkeley Laboratory Report LBL-26259 (1988) B Z Herd<. F G FUJIw&X &f rZ &%IV~ C H ZhiiTlOE bd ht A PdiiE~ .t’O.FA BZ, 823 (l\f83) w c MJh 44s Pboln-Bu)) 16, 3 J19-0, R C Kelly J- r3ils c’ifem &f u”ara io; suppl’ no I’ t’iYX1’) E Jannrtrr P N~colosr and G Tondrljo Plr,c Stqnm 4I. 458 $1990) U Feldman and L Cohen Asrrophbs J 158, L169 (1969) J F Seely, R H Dixon and R C Elton. Ph~s Rev A 23, 1437 (1981) J A Bearden. m CRC Handbook gf’C71em~r~ urtd Phstcr R C Weast and M J Astie ed . CRC Press Boca Raton. FL (1982)