Atomic collisions in fusion plasma physics

1. Atomic collisions in fusion plasma physics An introduction to the course Atomic Physics in Fusion, ED2235 Henric Bergsåker 26 Oct 2011

2. Atomic collisions in fusion • Atomic collisions and plasma performance Plasma resistivity and ohmic heating Radiative cooling Transport Collisions in edge plasma physics Ion implantation and backscattering at surfaces Sputtering at surfaces • Diagnostics involving atomic collisions • Types of collisions • Classical mechanics vs Quantum mechanics • Key quantities • Course outline and schedule

3. Plasma resistivity The plasma resistivity is due to elastic collisions

4. Radiation losses In a low density plasma the charge state distribution and radiating power density depends on electron impact ionisation and excitation. Plots: Y. Ding, Master thesis KTH 2008

5. Transport and collisions Classical diffusion Neoclassical diffusion Parallel transport on open field lines is important for impurity control with a divertor. Impurities created in the divertor are confined there by the collisional friction drag by the majority ion flow towards the divertor plates.

6. Backscattering at surfaces Upper: H -> C W.Eckstein et al. Lower: C -> C H. Bergsåker et al.

7. Ion implantation W. Eckstein et al. 2005

8. Physical sputtering Upper: few collisions view, J. Bohdansky. Lower: Monte-Carlo (TRIM), W Eckstein et al.

11. Modelling of deposition in castellation gaps. Experiments in TEXTOR A. Litnovsky et al. , PSI San Diego

12. X-ray tomography m/n=1 mode behaviour during sawtooth activity in the HT-7 tokamak. T.P. Ma et al. Phys. Lett. A361(2007)136.

13. Neutral particle analysis The central ion temperature can be measured by neutral particle analysis. M. Bagatin et al. Fus. Eng. Design 25(1995)425.

14. Charge exchange spectroscopy Studies of fully stripped O following H0+O8+ -> H++(O7+)* R.C. Isler et al. Nucl Inst. Meth. B9(1985)673.

15. Charge exchange spectroscopy Fast CXRS in JT-60U. Measurements of Ti and grad Ti using a line in the C5+ spectrum After H0+C6+ -> H++(C5+)* M. Yoshida et al. Fus. Eng. Des. 2009 in press.

16. Impurity and H flux from emission spectroscopy The images show hydrocarbon emission from the divertor region of DIII-D. In principle the flux density of neutrals entering the plasma can be measured spatially resolved in this way. M. Groth et al. J.Nucl.Mater 363-365(2007)157.

17. Atomic beam edge diagnostics Observation of three lines in neutral He. The intensity ratios give both Te and ne B. Schweer et al. J.Nucl.Mater. 266- 269(1999)673.

18. Important types of collisions • Elastic collision • Bremsstrahlung • Electron impact ionisation • Electron impact excitation • Radiative recombination • Dielectronic recombination • Charge transfer

19. Classical vs Quantum mechanics

20. Intended learning outcomes Having completed the course you should be able to: • Recall definitions of basic concepts in atomic physics and the size of key atomic quantities • Apply methods of wave mechanics and classical mechanics&electrodynamics to problems in atomic physics • Explain the significance of different approximations when estimating atomic quantities • Predict the general behaviour of fusion relevant atomic physics quantities based on dominating physical mechanisms • Construct simple numerical or analytic models of fusion plasma phenomena with input from atomic physics databases • Present and discuss fusion related atomic physics material, both in writing and orally

21. Schedule Tentative schedule sem = seminar room 1419, Teknikringen 31 kosm= kosmos, top floor Henric Bergsåker, henricb@kth.se, 08-7906094, 073 9850300

22. Examination • Five assignments, solving problems and discussing fusion plasma physics issues involving atomic physics (50%) • Presentations (10%) • Final written examination: basic facts, solving problems, discuss the physics (40%)