Trapped in Shanghai Spectroscopy with the Shanghai Electron Beam Ion Traps

Transcription

1 Trapped in Shanghai Spectroscopy with the Shanghai Electron Beam Ion Traps Roger Hutton! "#on behalf of the Shanghai EBIT laboratory Modern Physics Institute, Fudan University, Shanghai China

2 Outline Where are we A little about EBITs and our EBITs in Shanghai What are we doing with our EBITs Concluding remarks

3 China

4 Shanghai

5 Fudan University

6 15th International Conference on the Physics of Highly Charged Ions

7 Modern Physics Institute Mei you picture of the building! Prof. Fujia Yang Current name is Department of Nuclear Science and Engineering

8 What is an EBIT? Electron Beam Ion Trap A device for the production and storage of highly charged ions for spectroscopic and electron-ion collision studies, going back over 20 years. In 2006 Peter Beiersdorfer held a workshop 20 years of EBIT spectroscopy Not long after the success of studies with the ions in the trap, the idea that the ions could be extracted for other studies was born (Dieter Schneider)

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10 Electron beam ion traps, EBIT $%&'(#)*+,#-,,.#/ #*71854#(/,470*#(5.4,#9:;<#!==>="# Livermore (USA), Oxford (UK, now in Fudan), NIST (USA), Tokyo (Japan), Berlin (Germany, moved to Greifswald), Heidelberg (Germany), Dresden (Germany), Shanghai, Belfast (UK), Stockholm (Sweden) and a few more under development.

11 Little History A little history of the Shanghai EBIT laboratory

12 More History History of the Shanghai EBIT laboratory The project began in st electron beam in the high energy EBIT in st papers on DR for Xenon around st baby EBIT a few years back 1 st Spectroscopy papers 2012.

13 Shanghai EBITs The original The Baby The new ones

14 High Energy EBIT Some operating parameters of our old high energy EBIT: Electron beam energy: 130 kev At a current of 150 mamps Magnetic field, up to 5 T How do we know the electron beam radius? Electron beam diameter, around 80 microns (FWHM) giving a current density of around 2000 A/cm 2

15 Permanent Magnet EBIT Operating parameters of the Shanghai permanent magnet EBIT (SH-Perm EBIT or Shanghai Baby) Shanghai permanent magnet EBIT( EBIT) : eV : 10 ma : 0.5T Recently we made a few modifications following a lot of simulation work and we managed to run at a beam energy as low as 60 ev

16 High Temperature Superconducting EBIT!Maximum magnetic field 0.4 T Beam energy down to 30 ev Cobit 150eV FLASH-EBIT 105eV Berlin-EBIT 190eV Livermore EBIT 140eV SH-PermEBIT SH-HtscEBIT 60eV 30eV

17 Motivation for the low energy EBITs Study spectroscopy of low charge states of tungsten, ITER plasma diagnostics. The atomic structure for many of the ions in the charge state region of is very complicated, and in some cases it is not even possible to establish (easily) the electronic ground configuration. In W 7+ it is not clear whether 4f 13 5s 2 5p 6 2 F 7/2 or 4f 14 5s 2 5p 5 2 P 3/2 is the lowest level of the ground state 4f and 5p orbitals have almost the same binding energy

18 Spectroscopic data up until 1986!! The figure is from 1986 and of course the situation is a little better now, but not that much better. Look at Tungsten, Z = 74

19 Tungsten and the NIST data tables "#!"$%$&'($!$)!)*+!,-)+(-$./-$0!1/-2+(+-3+!/-!4)/&53!$-6!7/0+3'0$(!8$)$9!",:;9!<=><!! The bottom line is that not enough is known about Tungsten spectroscopy

20 Our Tungsten work So much data missing and needed, where to start? W 27+ (Ag-like) relatively simple 4d 10 4f which gives a 2 F term magnetic dipole transition between the 2 F 5/2 and 2 F 7/2 levels. a) Visible transition b) Relatively simple atomic structure c) Sufficient confusion in the literature and reasons to doubt the fine structure energy value quoted in the review by Kramida and Shirai

21 W 27+ spectroscopy Visible spectra taken at the SH-Permanent magnet EBIT. The electron beam energies used were 770, 880, 1050, 1100, and 1200 ev with the beam current of 5.5 ma. W 27+! W was injecting into the EBIT using the volatile compound W(CO) 6. The W F 5/2! 2 F 7/2 M1 line can be seen to appear between 337 and 338 nm. The line between 389 and 390nm is from W 26+ and the line at nm is a very strong N 2 + line, from the residual gas inside the EBIT trap.

22 Iso-electronic study of the M1 transition in Ag-like ions

23 More iso-electronic for the Ag-like ground state fine structure Points for Z = 70 and 74 from direct observations of the ground state M1 line. Other points are from Sugar and Kaufmann and the fine structure is derived from soft x ray transitions into the ground state levels.!!?!!!!!!!!+0+&+-)!!!!!!!!!!!!!@abc! <B! C8! 9DD9EFD! <E! $3! 9E9E<FD! <G! H2! 9BB@DFD! <D! '-! :IBDFI! <<! JK! ;GG<F@! <I! L1! IG99FG!

24 W 26+ energy levels Based on the results for Ag-like W (W 27+ ) we moved our attention to W 26+ (Cd like) MCDF calculated ground state fine structure level energies and possible transitions.

25 Experimentally determined W 26+ energy levels Energy-level diagram for the Cd-like tungsten based on the wavelengths measured in our work. A is either the 3 F 3 or 1 G 4 while level B is vise-versa, additional spectroscopy needed. The 1 D 2 level was placed according to the RMBPT-FAC energy calculation.