Kondo, K.

Marmar, E.S.

Rice, J.E.

Terry, J.L.

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PFC/JA-86-43Precision Measurements of the Wavelengthsof Emission Lines of Mg-like and Na-likeKv in Alcator C PlasmasK. Kondo, J.L. Terry, J. E. Rice, E. S. MarmarPlasma Fusion CenterMassachusetts Institute of TechnologyCambridge, MA 02139July 1986Submitted to: Physics Letters AThis work was supported by the U.S. Department of Energy ContractNo. DE-AC02-78ET51013. Reproduction, translation, publication, useand disposal, in whole.or in part by or for the United States govern-ment is permitted.By acceptance of this article, the publisher and/or recipient ac-knowledges the U.S. Government's right to retain a non-exclusive,Precision Measurements of the Wavelengthsof Emission Lines of Mg-like and Na-like Krin Alcator C PlasmasK. Kondo*, J. L. Terry, J. E. Rice, E. S. MarmarPlasma Fusion Center, MIT, Cambridge, Massachusetts, USA 02139*Plasma Physics Laboratory, Kyoto University, Kyoto, JAPANAbstractThe wavelengths of lines from Na- and Mg-like Kr ions were precisely deter-mined by puffing Kr gas into Alcator C tokamak plasmas and observing with atime-resolving spectrograph equipped with a multi-element spectral detector.1Recently the possibility of laser action in UV and X-ray regions has beendiscussed widely [1]. Kr is considered one of the promising elements, and it isimportant to measure the energy levels of its highly ionized states precisely.A powerful method for the study of emission spectra of highly ionized, medium-and high-Z ions is to introduce them into high temperature, magnetically confinedplasmas and observe the resulting emission with a time-resolving spectrograph.Kr was introduced into Alcator C tokamak [2] discharges by gas puffing, andKr ionization states up through Ne-like are obtained with ease. In these dischargesthe toroidal magnetic field was 8T, the plasma current was 290 kA, and the lineaverage electron density was 2.3 x 1014 cm- 3 . The radius of the plasma columnwas 12.5 cm. Central electron and ion temperatures were 1200 eV and 900 eVrespectively. Identification of Kr emission lines is made by comparing the spectraof discharges with large and small amounts of seed Kr.The VUV emissions from these plasmas were monitored by a 2.2 m. grazingincidence spectrometer with a spectrally resolving detector on the Rowland circle.The detector observes about 30-40 A of the spectrum with approximately 0.2 Aresolution and can be scanned from ~ 28 A to 570 A in first order. It is composedof a micro-channel plate with a CsI photo-cathode, backed by a phosphor screenwhich is coupled by a fibre-optic bundle to a 1024 pixel, photodiode array. Thearray can be read out every 2,4,8,16,32,64, or 128 msecs.In Fig. 1 is shown a composite spectrum from 5 discharges into which onlytrace amounts of Kr were puffed. The most prominent features are from intrinsicoxygen in the plasma. The following lines are used for wavelength calibration: OVI(150.089 A,150.124 A), OVI (172.935 A, 173.082 A), OVI (183.937 A, 184.117 A),OV (192.751 A, 192.799 A, 192.906 A), OV (215.040 A, 215.103 A, 215.245 A), andOV (220.352 A) [3]. Shown in Fig. 2 is the same region of the spectrum when2significantly more Kr is puffed into the discharge. (Z,f f-1 due to Kr is ~ 0.1 forthese discharges.) In this spectrum the Kr lines dominate. The emission line at158.23 ±0.05 A is identified as the 3s2 ISO - 3s3p 'P* transition in Mg-like Kr.This line has also been identified by Stewart, et. al. [4], who give the wavelength as158.15 ± 0.03 A. The line at 179.03±0.03 A is from Na-like Kr (3s 2Si. -3p 2 P2 2given in [4] as 178.98±0.03 A. This compares favorably to the prediction of 178.97 Aby Edlen [5]. The other member of the Na-like doublet (3s 2 S, - 3p 2p,), is2 2observed at 220.05 ± 0.01 A, given in [4] as 220.07 i 0.05 A, and predicted by ref.[5] to be 220.03 A. The results are summarized in Table 1.Table 1Transition Array Multiplet Wavelength (A) this work Wavelength (A) ref. [4]Kr XXV3s2 - 3s3p ISO -1 P1 158.23 ±0.05 158.15 ± 0.03Kr XXVI3s - 3p 2s. _2 P 179.03 ± 0.03 178.98 ± 0.032 23s - 3p 2 2 220.05 ± 0.01 220.07 ± 0.052 2Thus the 3s3p 1Pl, the 3p 2 P. and the 3p 2 P levels are found to be 6321902 2cm- , 558570 cm~1 and 454440 cm-1 above the ground states respectively. Fig.3 confirms the Mg-like and Na-like identifications by showing the regularity in thelevel energy of the Kr levels when plotted with the energies of ions from Sc throughMo. These data up to Mn are derived from [6], while those for Fe through Ni arefrom [7]. The values from Na-like of Cu through Br are derived from the data ofKononov, et al. [8]. The data for Zr and Mo are from Hinnov [9] and Shirai, et al.[10] respectively.Finally, Edlen [5] has determined a scaling relation for the energy of the 3p 2 P2325 -- .. It. .. t25E-NCO0 M01 CO N2 N ko M CO Q000140 150 160 170 180 190 200 210 220WAVELENGTH (A)Figure 1. Composite spectrum from 5 similar discharges when onlytrace amounts of Kr were present.4200 I I I I I I I I15010050046'-4- d- IC,'.4C)I0CV)014146'.4CfaoeCQ.Cv- 6 C,, C0 -CQI I I I I I I I140 150 160 170 180 190 200 210 220WAVELENGTH (A)Figure 2. Composite Kr spectrum when enough Kr was puffed into thedischarge so that Zff-1 due to Kr was ~ 0.1.5zIE-I I I I I I I I1.0000.5e o0 23p P1 2, * *0 Sc Ti V Cr Mn Fe Co Ni CU Zn Ga Ge As Se Sr Kr Rb Sr Y Zr Nb MoFigure 3. Regularities in the energy above the ground state for the3-93p 'P* level of the Mg-like ion and the 3p 'PA* levels of the Na-like ion.2, .- 26level above the ground state, which includes the effects of the Lamb shift of the 3sground state. It isAE(cm-1) = 16481.6(Z - 10) + 10163 - 27800(Z - 8.7)-i + 0.700(Z - 6)3 - L(3s),where Z is the nuclear charge and L(3s) is the Lamb shift. The measured wavelengthimplies a Lamb shift of the 3s ground state of 2120±20 cm-1, where the uncertaintyreflects only the uncertainty in the wavelength and does not include errors in thescaling relation.In conclusion, the wavelengths of the 3p 2P. I -- 3s 2Si transitions in Na-2'2 2like Kr and the 3s3p 'P* -+ 382 1So transition in Mg-like Kr have been determinedby puffing Kr into Alcator C discharges and observing the emissions with a time-resolving spectrograph.AcknowledgmentsThe authors would like to thank Dr. R. R. Parker and the Alcator C staff.One of us (K.K.) acknowledges the support fo the Japan Society for the Promotionof Science and Professors K. Uo and A. Iiyoshi for support of his visit to the PlasmaFusion Center at M.I.T. We also thank R. E. Stewart, D. D. Dietrich, R. J. Fortnerof the Lawrence Livermore Nat. Lab. and R. Dukart of Physics International Co.for access to their manuscript which was being prepared for publication and whichconcerned spectra of highly ionized Kr, line identifications, and analyses. Worksupported by U. S. Department of Energy contract number DE-AC02-78ET51013.References1]. U. Feldman, A. K. Bhatia, S. Suckewer, J. Appl. Phys., 54, (1983), p.2188.2]. R.R. Parker, et al., Nucl. Fusion, 2!, (1985), p. 1127.3]. R.L. Kelly, Atomic and Ionic Spectrum Lines Below 2000 A, H throughAr, ONRL-5922 (1982).74]. R.E. Stewart, D.D. Dietrich, R. J. Fortner, R. Dukart, to be published inJ. Phys. B. and R.E. Stewart, Ph.D. Dissertation, U. C. Davis (1984).5]. B. Edlen, Physica Scripta, 17, (1978), p. 565.6]. S. Bashkin, J.O. Stoner, Atomic Energy Level and Grotrian Diagrams,vol. II-IV, North-Holland Pub. Co. (1978,1981,1982).7]. J.R. Fuhr, G.A. Martin, W.L. Wiese, S.M. Younger, J. Phys. Chem. Ref.Data, 10, (1981), p. 305.8]. E.Ya. Kononov, A.N. Ryabtsev, S.S. Churilov, Physica Scripta, 19, (1979),p. 328.9]. E. Hinnov, in Atomic Physics of Highly Ionized Atoms, ed. R. Marrus,Plenum Press. (1983).10] T. Shirai, K. Ishii, K. Mori, Y. Nakai, K. Ozawa, JAERI-M 85-173 (1985).8

Precision measurements of the wavelengths of emission lines of Mg-like and Ma-like Kr in Alcator C plasmas

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Precision measurements of the wavelengths of emission lines of Mg-like and Ma-like Kr in Alcator C plasmas

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