This work was performed under the auspices of the U.S. Department of Energy by under contract DE-AC52-7NA27344. Lawrence Livermore National Security, LLC
The ITER tokamak Tungsten (W) is attractive as a plasmafacing material in magnetic fusion devices high melting point, low tritium retention, high-energy sputtering threshold, low sputtering yields Several present-day fusion devices operate with tungsten components The ITER tokamak will have a W divertor Several research efforts tackle the material science and atomic physics of tungsten Radiative properties of tungsten ions are required for the diagnostics of tungsten influx and transport as well as for measurements of local plasma parameters Atomic data on tungsten needed EBIT spectroscopy perfectly suited 2
EBIT and magnetic fusion plasmas have similar densities Magnetic fusion plasmas often have several ion species EBIT plasmas have one or a few In fusion plasmas numerous atomic processes interact EBITs can isolate these processes Fusion plasmas have bulk motions and high temperatures EBIT plasmas are cold and stationary core Te = 1 4 kev ne = 114 cm-3 main chamber similar spectral emission Eb = 3 ev 2 kev ΔE 3 ev ne = 111 12 cm-3 Be first wall divertor Te = 1 15 ev ne = 114 15 cm-3 divertor chamber W divertor The ITER tokamak EBIT 3
1 H 8755.6 3 4 Li Be 19691 19362 11 12 K shell L shell M shell N shell O shell La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu He B C N O F Ne ionization energy (ev) Na Mg Al Si P S Cl Ar 713 19 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb 1621.7 55 7 2 Sr 1569.1 56 21 Y Zr Nb 1386.7 73 Mo 1335.1 74 Cs Ba Hf Ta W 22 23 24 25 Tc 26 Ru 27 number of electrons isoelectronic sequence Rh Pd 74 W 7.8643 5348 529 563 4927 479 4578 4446 439 418 457 2414.1 2354.5 221. 2149.2 1994.8 194.6 1883. 1829.8 37 38 39 4 41 42 43 44 45 46 47 48 49 5 51 52 53 54 52.6 462.1 1512.4 1459.9 72 26. 16.37 7.8643 28 57 58 59 6 61 62 63 64 65 66 67 68 69 7 71 42.7 387.9 tungsten charge-state table 361.9 325.3 1283.4 29.7 123.4 258.2 1179.9 231.6 1132.2 29 28.9 Ag 881.4 3 179. Cd 833.4 79181 5 6 7 8 9 1 18872 13 6735 31 16.2 In 784.4 18476 14 6596 32 141.2 Sn 734.1 16588 15 693 33 122.1 Sb 685.6 16252 16 597 34 64.77 Te 64.7 15896 17 584 35 51.6 I 594.5 2 15566 18 5719 36 38.2 Xe 543.4 EBITs can create all tungsten charge states 4
Strong EUV quasicontinuum emission from tokamaks with tungsten plasma-facing components The large radiation losses associated with the W quasicontinuum led to the abandoning of high-z elements in fusion devices Densely spaced line emission from n = 4 4 transitions from tungsten ions of many charge states ORMAK Alcator C-Mod PLT 3 4 5 6 7 4 5 6 7 W spectra from the Oak Ridge ORMAK (Isler 1977) and the Princeton PLT (Hinnov 1978) tokamaks Time-resolved W spectra from the MIT Alcator C- Mod tokamak (Podpaly 211) 5
EBIT groups at Berlin and Livermore have studied W N-shell ions by adjusting the e-beam energy Berlin EBIT E beam =.54 4.6 kev Livermore EBIT-II E beam = 1.79 3.2 kev I-like W 21+ Ni-like W 46+ Rb-like W 37+ Cu-like W 45+ 3.2 2.71 2.46 Intensity (arb. unit) Intensity (arb. unit) 2.37 2.1 2.5 1.95 1.89 1.79 5 6 7 W spectra from the Berlin EBIT (Biedermann 21) 4 5 6 7 8 W spectra from the Livermore EBIT-II (Utter 22) 6
Low charge states of tungsten will be abundant in ITER divertor plasmas (T e = 1 15 ev) O V O V W VII 5p - 5d O IV SSPX shot # 29 W VII 5p - 5d Strong and densely spaced EUV emission Low-energy operations of EBITs can simulate ITER divertor emission Intensity (arb. unit) O VI W VII 5p - 6s W VII 5p - 6s W W VII 5p - 5d W VII 5p - 6s W VII 5p - 6s O IV O V Ti EBIT-I at E beam = 135 ev W VII 5p - 5d W VII 5p - 5d W VII 5p - 6s EBIT-I at E beam = 163 ev W VII 5p - 5d ITER divertor cassette 18 2 22 24 26 28 Tungsten spectra observed at the Livermore SSPX spheromak and the Livermore EBIT-I 7
Two-body recombination processes are important line-formation mechanisms in EBIT plasmas DR and RR are important for the ionization balance in fusion plasmas RR and DR in highly charged W ions have been studied at the Tokyo and Berlin EBITs Radiative Recombination (RR) 2p6 + εκ Dielectronic Recombination (DR) dielectronic capture 2p6 + εκ radiative stabilization E IE IE E 2p6 nl 2p6 nl EIE, DR, and RR with Ne-like W64+ at the Tokyo EBIT (Watanabe 27) 8
W n = 2 3 x-ray transitions are the physics basis for the ITER Core Imaging X-ray Spectrometer Ion-temperature and plasma-rotation profiles from Doppler broadening and shifts of W x-ray lines EBITs can provide high-precision near-doppler-free reference data ΔE shift v = c! "E shift E E E # T i! M "E & width % ( $ ' ΔE width E 2 Counts 16 8 3B 3C plasma f s spherical crystal Rowland circle R c fm detector ITER spectrometer principle 1 3 1 4 X-ray energy (ev) Ne-like W 64+ measured at the Livermore EBIT-I (Beiersdorfer 1993) 9
Tungsten L-shell ions (Ne-like W 64+ Li-like W 71+ ) will be abundant in ITER core plasmas Groups of strong x-ray transitions 2p 1/2 2p 3/2 M1 and E2 transitions 12 15 ev 2s 1/2 2p 3/2 E1 transitions 16 19 ev 2p 3/2 3s 1/2 E1 (and M2) transitions 8 9 ev 2p 3/2 3d 5/2 E1 transitions 9 1 ev Fractional abundance.4.3.2.1. 1 W 62+ W 61+ W 6+ W 64+ W 63+ W 65+ W 66+ W 67+ W 68+ 2 3 Electron temperature (kev) 2s 1/2 2p 1/2 2p 3/2 3s 1/2 3p 1/2 3p 3/2 3d 3/2 W 69+ W 7+ W 71+ 4 Counts 2 1 n = 2 - n = 2 n = 2 - n = 3 E beam = 51 kev 8 Counts 4 W 7+ W 69+ W 69+ W 68+ W 67+ W 66+ W 67+ W 67+ E beam = 13 kev silicon W W 65+ 71+ W 66+ 1 3 5 7 X-ray energy (kev) W L-shell transitions measured at the Livermore SuperEBIT (Clementson 21) 9 11 13 17 18 X-ray energy (ev) 19 W L-shell transitions measured at the Livermore SuperEBIT (Podpaly 29) 1
High-order multipole (forbidden) transitions in highly charged ions can produce strong lines in low-density plasmas 15 1 5 5355 V interesting for electron-density diagnostics important for charge-balance modeling 15 1 5 55 Ti Magnetic dipole (M1), electric quadrupole (E2), and magnetic octupole (M3) transitions in W have been studied at several EBIT laboratories Counts 1 5 15 5755 6 Ca Sc 1 Counts 15 1 5 Ni-like W 46+ E2 M3 5 6 3 1 65 7 K Ar Cl 5 7.88 7.9 7.92 7.94 7.96 7.98 1 12 14 16 18 2 W E2 and M3 transitions measured at the Livermore SuperEBIT (Clementson 21) W M1 transitions measured at the NIST EBIT (Ralchenko 211) 11
Optical transitions have been studied at several EBIT labs 33 ev Neutral to highly ionized tungsten 36 ev Intensity (arb. unit) Ti-like W 52+ 3d 4 5 D 2-5 D 3 Intensity (arb. unit) 4 ev 45 ev 358 362 366 37 36 38 4 Optical M1 line from Ti-like W 52+ measured at the Livermore EBIT-II (Utter 2) Optical transitions at the Tokyo CoBIT (Komatsu 211) 12
Tungsten is of interest to benchmark high-precision atomic calculations multi-electron systems with strong relativistic and quantum electrodynamical effects EBIT measurements of highly ionized few-electron W atoms (Li-, Be-, Na-, Mg-like W) EBIT measurements of moderately ionized many-electron atoms (Pm-like W 13+ ) 2s 1/2-2p 1/2 Intensity (arb. unit) predicted at 64.1 Å 2s 1/2-2p 3/2 335 355 375 395 Lines from ions around Pm-like W 13+ measured at the Berlin EBIT (Hutton 23) Li-like ion lines (Kramida 211) including W 71+ from the Livermore SuperEBIT (Clementson 211) compared with theory (Blundell 1993) Z 13
Atomic radiative and collisional data on tungsten are needed for fusion plasma diagnostics EBITs are ideal light sources for high-precision atomic physics measurements create, excite, and confine ions of any tungsten charge state EBIT spectra are similar to magnetic fusion spectra due to similar densities specific processes can be studied with EBITs EBIT measurements are not Doppler limited Fusion plasma spectra can be analyzed with EBIT spectroscopy New diagnostics for fusion plasmas can be identified and developed using EBIT spectroscopy Several fusion-motivated tungsten spectroscopy projects have been performed at EBIT labs Tungsten spectra measured at EBITs are good for testing atomic calculations and modeling 14
EBIT Joel Clementson clementson@llnl.gov