NICKELLIKE GADOLINIUM SPECTRA FROM THE PLT TOKAMAK

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NICKELLIKE GADOLINIUM SPECTRA FROM THE PLT TOKAMAK

S. von Goeler, P. Beiersdorfer, M. Bitter, R. Bell, K. Hill, P. Lasalle, L.

Ratzan, J. Stevens, J. Timberlake, S. Maxon, et al.

To cite this version:

S. von Goeler, P. Beiersdorfer, M. Bitter, R. Bell, K. Hill, et al.. NICKELLIKE GADOLINIUM

SPECTRA FROM THE PLT TOKAMAK. Journal de Physique Colloques, 1988, 49 (C1), pp.C1-

181-C1-184. �10.1051/jphyscol:1988134�. �jpa-00227454�

NICKELLIKE GADOLINIUM SPECTRA FROM THE PLT TOKAMAK

S. von GOELER, P. BEIERSDORFER, M. BITTER, R. BELL, K. HILL, P. LaSALLE, L. RATZAN, J. STEVENS, J. TIMBERLAKE, S. MAXON*

and J. SCOFIELD*

Plasma Physics Laboratory, Princeton University, Princeton, NJ 08544, U.S.A.

" ~ a w r e n c e Livermore National Laboratory, Livermore, CA 94550, U.S.A.

Abstract:

Spectra in the 7 to 9 A region of gadolinium were measured on the PLT tokamak with a vacuum curved crystal spectrometer. The wavelength are compared with theoretical predictions from the RAC code for iron, cobalt, nickel, copper, and zinciike chargestates.

On tokamaks, K-spectra (n = 2 to 1) of highly ionized atoms have been investigated in great d e t a i ~ ' , ~ , ~ . They serve as a diagnostic to measure impurity concentrations, ionic charge state distributions, ion temperatures, and plasma rotation velocities. An investigation of L spectra (n = 3 to 2) has also begun on t o k a m a k ~ ~ ? ~ ~ ~ . The L-spectra are important for radiation loss and impurity transport.Furthermore, great interest in neonlike s ectra was generated by the successfuII X-ray lasing experiment based on neonlike selenium? Recently, collisionally pumped X-ray laser work has expanded to include schemes based on nickellike ions8. Consequently, we have injected a few very high Z elements into PLT, notably gadolinium, in order to study M-spectra(n=4 to 3).lt should be stressed that the experiments represent a very preliminary and exploratory investigation. Moreover, since the dispersion range of nickellike spectra is very large, the measured spectra are incomplete. Nevertheless, because they seem to be the first measured 4 - 3 spectra from a low density plasma in the soft X-ray region, it appears worthwhile to investigate them further.

The spectra have been produced by injecting metal vapor from the laser blow-offg of gadolinium coated glass slides. The spectra were recorded with a vacuum curved crystal spectrometerlo which had been set up on PLT in the 7 - 9

A

region (for the investigation of neonlike selenium), and consequently only spectra in this wavelength region were recorded. The wavelengths were measured by simultaneously injecting sodium and magnesium, and by comparing the gadolinium lines with well known helium and hydrogenlike transitions of these lighter ions.The reference lines used in this work are listed in Table I. For the hydrogenlike lines, Garcia's and Mack's wavelengthsl1were used. There, the wavelengths are averaged over the two angular momentum states. Safranova's wavelengthsq2 were used for the heliumlike transitions.

The measured gadolinium spectra are shown in Fig.1. They were recorded approximately between 20 and 100 ms after laser injection. A background spectrum which was recorded before gadolinium injection was subtracted in order to eliminate the naturally occuring background of iron and nickel lines. The observed spectral features, their wavelengths, intensities, proposed assignments and gf values are listed in Table 2. It should be stressed that the quoted intensities are questionable, because the spectra in Fig. l a , lb, and I c were taken in different discharges, with different amount of impurity injection, and because a vignetting analysis and correction has not yet been performed for these spectra. It should also be mentioned that the accuracy of the experimental wavelength is only about 4 mA. Considering only the line fitting procedure, we expected an accuracy better than 1 mA. However, a comparison of data from different run days, revealed discrepancies which are not yet explained, and which are believed to originate from the microchannel plate detector.

The theoretical wavelengths have been calculated with the RAC code in Liveremore, a relativistic configuration interaction calculation using Hartree-Fock orbitals. All lines represent strong electric dipole transitions to the groundstate of the ions. The agreement between the theoretically predicted and the experimental wavelengths is in general better than 10 mA.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1988134

C1-182 JOURNAL

DE

PHYSIQUE

As is to be expected, the strongest lines in Fig. 1 are the nickellike electric dipole transitions at 7.64

A,

8.53

A

and 8.77

A.

Two of these transitions have been observed earlier in high density We also see strong lines from lower charge states, like a copperlike line at 8.60

A

or a zinclike line at 8.69 Lines from higher charge states are also prominent, for example two cobaltlike lines at 8.30

A

and at 8.55

A

and a doublet of ironlike lines around 8.08

A.

This is expected from Corona equilibrium calculations which predict a significant amount of gadolinium to be in these charge states.

In summary, we present here the first low density nickel-like n = 4

-

3 spectra in the soft X-ray region from a tokamak. Most features of these spectra agree qualitatively with the predictions of the RAC oode. A more quantitative analysis is left for the future.

#87X0702

(a)

X I

7.4 7.5 7.6 7.7 7.8 7.9 8.0 8.1 8.2

Fig.1: Spectrum of gadolinium in the 7 to 9

A

region.The spectral features labeled 1 through 54 are explained in Table II.Subfigure (a), (b), and (c) are from different PLT discharges.

# Transition Lambda (expt.) Lambda gf Ampl. Comments Ref.13 present (theor.)

. . .

01 co(3p33/23d55/24d5/2)7/2 7.453 7.441 1.04 80

c o ( 3 ~ 3 3 / 2 3 d 5 5 / 2 4 d 5 / 2 ) 3 / 2 7.479 .78

02 7.514 7.503 .96 70

03 ~ o ( 3 ~ ~ 3 / 2 3 d ~ 5 / 2 ~ d 5 / 2 ) 7 / 2 7.533 7.529 .43 50 Noise?

04 c0(3p33/23d55/24d5/2)5/2 7.542 7.539 1.06 70 Blend with 5

0 5 7.544 100 Blend with 4

06 ~ i ( 3 ~ ~ ~ / 2 4 d 5 / 2 ) l 7.638 7.626 1.08 1 7 0 0

0 7 7.660 100 Strong background1

08 C u ( 3 ~ ~ ~ / 2 4 ~ ~ d 5 / 2 ) 3 / 2 7.674 7.660 .26 80 Noise?

0 9 ~ u ( 3 ~ ~ ~ ~ 2 4 ~ 4 d 5 / 2 ) 1 /2 7.698 7.667 .55 150 Blend with 10 1 0 cu(3p33/24s4d5/2)3/2 7.703 7.685 1.14 480

1 1 Fe(3p3l123d45/2 4s112)5 7.709 7.698 .37 130 Blend with 10

1 2 7.732 130 Blend with 13. Noise?

13 7.734 150

1 4 ~ n ( 3 ~ ~ ~ / 2 4 s ~ 4 d 5 / 2 ) 1 7.750 7.737 1.00 200

Fe(3P3 1 /23d45/2 4s1 1214 7.738 .23

1 5 ~ e ( 3 ~ ~ ~ ~ ~ 3 d ~ 5 / 2 4sj12)4 7.783 7.753 .14 70 Noise?

1 6 7.882 100 Line 16 through 20

1 7 7.887 130 form one large blend,

1 8 7.894 100 which also falls into a

19 7.898 120 region of large back-

20 7.91 3 60 ground subtraction.

2 1 7.924 50 Noise?

22 ~ e ( 3 d ~ ~ ~ ~ 3 d ~ ~ / ~ 4 f ~ / ~ ) ~ 8.084 8.081 11.9 410 23 ~ e ( 3 d ~ ~ ~ ~ 3 d ~ 5 / 2 4 f ~ / ~ ) ~ 8.090 8.094 13.57 420

24 8.095 200 Between 24 and 25 lies

25 ~ e ( 3 d ~ ~ ~ ~ 3 d ~ 5 / 2 4 f ~ ~ ~ ) ~ 8.1 1 0 8.1 08 3.5 130 a blend of many lines.

Fe(3d33/23d45/*4f 5 1 2 ) ~ 8.118 4.04

26 8.140 160

27 ~ e ( 3 d ~ ~ / ~ 3 d ~ ~ / ~ 4 f ~ / ~ ) ~ 8.205 8.200 .17 70 Noise?

28 ~ e ( 3 d ~ 3 / ~ 3 d ~ 5 / 2 4 f 5 / 2 ) ~ 8.257 8.238 .41 70 Noise?

2 9 8.280 80 Noise?

3 0 c0(3d33/23d55/24f5/2)7/2 8.303 8.281 15.7 3 2 0 0

co(3d33/23d55/24f5/2)5/2 8.285 11.3

31 co(3d33/23d55/24f5/2)3/2 8.31 3 8.302 3.8 660 Strong bckgdsubtract.

3 2 ~ e ( 3 d ~ ~ / ~ 4 f ~ ~ ~ ) ~ 8.335 8.332 .6 380

3 3 ~ e ( 3 d ~ ~ ~ ~ 4 f ~ ~ ~ ) ~ 8.360 8.353 .96 170 Between 33and36 lies 3 4 c 0 ( 3 d 3 3 / 2 3 d 5 5 / 2 4 f 5 / 2 ) 7 / 2 8.368 8.376 .27 230 a blend of lines that is 3 5 ~ e ( 3 d ~ ~ / ~ 4 f ~ ~ ~ ) ~ 8.386 8.381 .43 190 also region of strong 3 6 ~ e ( 3 d ~ ~ / ~ 4 f ~ ~ ~ ) ~ 8.398 8.389 .93 150 backgrnd subtraction.

3 7 ~ o ( 3 d ~ 3 / 2 3 d ~ 5 / 2 4 f ~ / 2 ) ~ ~ 2 8.439 8.437 .26 110 Noise?

3 8 ~ o ( 3 d ~ 3 / 2 3 d ~ 5 / 2 4 f 5 / 2 ) ~ / 2 8.463 8.450 .31 100 3 9 ~ i ( 3 d ~ ~ / ~ 4 f ~ ~ ~ ) ~ 8.54 8.530 8.515 6.5 7700

40 co(3d45/24f7/2)7/2 8.538 8.533 2.37 950

c0(3d45/24f7/2)5/2 8.535 1.6

41 8.554 1 0 6 0 Blended into 42

42 c0(3d45/24f5/2)7/2 8.556 8.568 .7 2600

C1-184 JOURNAL DE PHYSIQUE

Acknowledaements: The support of Drs. H.P.Furth, J. Hosea, K. Young, S. Bernabei, M. Eckart and A. Toor is gratefully acknowledged. Discussions with Dr. P. Hagelstein stimulated this work. The technical assistance of J. Gorrnan, J. Lehner and the PLT crew was excellent.This work was supported under DOE Contract DE-AC02-76-CHO-3073 and LLNL Subcontract 8-668-705.

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