On the broadenings of spectral lines emitted in surface wave discharges. M. Christova, L. Christov and M. S. Dimitrijević

Transcription

1 On the broadenings of spectral lines emitted in surface wave discharges M. Christova, L. Christov and M. S. Dimitrijević

2 Surface wave sustained discharge SW launcher E z S z S z v n 2 E n k z n k z S z pl S z 2

3 Filamentation of the discharge Djermanova N, Grozev D, Kirov K, Makasheva K, Shivarova A and Tsvetkov Ts 1999 J. Appl. Phys

4 Diagnostics methods for plasma parameters Probe diagnostics Microwave and Radiophysics methods Optical spectroscopy methods Without any perturbation of both - plasma and wave Profile, broadening and shift of the emitted spectral lines - information about the plasma parameters and interactions emitter-perturbers (charged and neutral particles). The methods based on the broadening of the lines emitted by the gas under investigation are seldom used for diagnostics of SWDs. 4

5 Spectroscopy diagnostics broadenings Aim: Experimental and theoretical investigation of broadening of spectral lines, suitable for electron density and gas temperature diagnostics of SWDs in the pressure range between Torr and 1 atm. Goals: Nonstationary regimes of SWDs - Experiment Stationary regime under atmospheric pressure - Experiment Modelling the pressure broadenings of Ar I lines: a) Calculations of Stark broadening parameters b) Calculations of neutral broadening using different potentials of interaction. 5

6 Nonstationary regimes of SWDs - Experiment Ar I nm Intensity, relative units pixels intensity in rel. units ν in cm -1 p = 1 Torr 6 (a) intensity in rel. units ν in cm -1 p = 104 Torr (b)

7 Experimental results: Gas temperature and electron density 1600 T e = K 1400 Gas temperature, K Pressure, Torr ( ) p =1Torrи 10 Torr ( ) at p = 20 и 40 Torr ( ) at p = Torr Griem s data 1962 Pellerin formula 1996 Christova M, Gagov V and Koleva I, Analysis of the profiles of the Argon 696,5 nm spectral line excited in nonstationary waveguided discharges Spectrochemica Acta B (2000)

8 Experimental results at 1 atm 0,14 0,12 0, W 150 W 200 W λ L, nm 0,08 0,06 0,04 0,02 z = 40 mm 0, n* λ (nm) Transition E u (cm -1 ) E l (cm -1 ) n* p 5 4d 3p 5 4p p 5 6s 3p 5 4p p 5 4d' 3p 5 4p p 5 5d 3p 5 4p Christova M, Castaños-Martinez E, Calzada M D, Kabouzi Y, Luque J M and Moisan M 2004 Applied Spectroscopy p 5 5d 3p 5 4p p 5 5d' 3p 5 4p p 5 6d 3p 5 4p p 5 7d 3p 5 4p

9 Theoretical results for Stark broadening parameters of argon lines To obtain Stark broadening parameters 522.1, 549.6, 518.8, 560.7, и nm visible optical Ar I линии Semi-classical theory of Sahal-Bréchot impact approximation within 9

10 Investigating the influence of: 1) Spin-orbital interaction 2) Coupling scheme 3) Oscillator strengths 10

11 W d = Sahal-Bréshot theory 2ne vf ii' ff ' v ( v) dv σ ( v) + σ ( ) + σ = n e 0 0 vf ρ d ( v) dv ρ 3 i' i 2πρdρ sin 2ϕ f ' f p el W W W in el = W in = W = W str in str el Input data n e, T, λ, m i, m p E ion, B, Z p, E i, E f, l i, l f, E i, E f, l i, l f, f if + W el + W + W w in w el Using cataloge Topbase LS (E, f ij ) Kurucz j-l (E, f ij ) NIST j-l (E) f ij Beits and Damgaard Output data W e, d e, W i, d i, W p, d p W str, d str, W el, W in, d in W q, d q, A 11

12 Temperature dependence of Stark broadening 7 6 Ar I nm β β = β = γ n β in + β el β, 10-4 cm 3 s β in β el = β p el + β q el 2 β p β el T e,k 12 M. Christova, S. Sahal-Bréchot and N. Allard GD 2004, K9, Sept. 5 10, Toulouse, France.

13 Temperature dependence of Stark broadening Ar I nm β, cm 3 s -1 x β β el β p β in T e, K 13

14 Comparison with experimental and theoretical results by other authors Ar I nm 7,5 jl-mult ,5 LS-mult 3,0 W [10-10 m] 5,0 2,5 jl-line K jl-line BD d [10-10 m] 2,5 2,0 1,5 1,0 0,5 LS-mult jl-mult 1964 jl-line BD 0, T e [K] 0, T [K] Dimitrijević M S, Christova M and Sahal- Bréchot S, Stark broadening of visible Ar I spectral lines, Phys. Scripta (2007) Griem 1974 Sahal-Bréchot quasistatic ions Schulz 1968; Bues 1969; Ranson

15 Comparison with experimental and theoretical results by other authors Ar I nm 7,5 3,5 3,0 W [10-10 m] 5,0 2,5 jl-line K LS-mult jl-mult 1964 jl-line BD d [10-10 m] 2,5 2,0 1,5 1,0 0,5 LS-mult jl-line BD 0, T [K] 0, T [K] Griem 1974 Sahal-Bréchot quasistatic ions Schulz 1968; Bues 1969; Ranson 1974; Kasakov

16 0,25 C 1 < 0,1 Ar I nm 0,25 C 1 < 0,1 0,20 jl-mult ,20 W [10-10 m] 0,15 0, d [10-10 m] 0,15 0,10 jl-mult ,05 0, ,25 0,20 T e [K] C 1 > 0,1 0,05 0,25 0,20 jl-mult , T e [K] C 1 > 0,1 jl-line jl-mult 1964 d [10-10 m] 0,15 0,10 0, jl-mult 1964 jl-line BD jl-mult 0, T e, K Griem 1962; 1964; Sahal-Bréchot 2002 quasist. ions; Popenoe; Tonejc; Ranson; Bakshi Djenize; Aparicio; Dimitrijevic Dzierzega 16 W [10-10 m] 0,15 0,10 0, , T e [K] jl-line BD

17 Criteria for impact approximation С 1 transitional range W exp / W th 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 C 1 < 0,1 0,1 < C 1 < 0,5 0,00 0,25 0,50 0,75 1,00 C 1 (ion parameter) C 1 > 0,5 Ar I nm * = str C1 τ W << 1 Griem Sahal-Bréchot impact ions Sahal-Bréchot quasistatic ions 17

18 Theoretical results for broadening of argon lines by neutral atoms Potentials of interactions: Van der Waals, Lennard- Jones and Kaulakys Axial variation of n e in capillary discharge at p = 1 atm by the pressure broadenings of Ar I lines, using the theoretical results 18

19 Potentials of emitter-atom interactions in ground state Van der Waals V ( R) = C R 6 6 Lennard-Jones Kaulakys 12 6 V ( R) = C12R C6R r r r r r V R = V R + V R, V e ( ) ( ) ( ) + V ( r R), c cе e 0 ( r R) = 2πLδ ( r R) r r R r > r V ( R) σ ( v) γ = βn 19

20 Van der Waals Lennard-Jones λ nm Legend β, 10-8 s -1.cm nm nm nm nm nm nm nm nm nm β, 10-8 s -1.cm T g, K T g, K β, 10-8 s -1.cm β, 10-8 s -1.cm Kaulakys β = 2vσ ( v) v ' T g, K β = 2 v σ ' ( v ) T g, K

21 Ar I nm Ar I nm 6,0x10-8 5,0x10-8 5,0x10-8 β, s -1.cm 3 4,0x10-8 3,0x10-8 2,0x10-8 β, s -1.cm 3 4,0x10-8 3,0x10-8 2,0x10-8 1,0x10-8 1,0x10-8 0, T g, K 0, T g, K 4,0x10-8 3,5x10-8 Ar I nm β, s -1.cm 3 3,0x10-8 2,5x10-8 2,0x10-8 1,5x10-8 1,0x10-8 5,0x10-9 0, β 1 ; β 2 ; β 3 ; β 1600 K 1atm L= -1.6a 0 T g, K 21

22 Ar I nm Ar I nm 1,4x10-7 1,4x10-7 1,2x10-7 1,2x10-7 β, s -1.cm 3 1,0x10-7 8,0x10-8 6,0x10-8 4,0x10-8 β, s -1.cm -3 1,0x10-7 8,0x10-8 6,0x10-8 4,0x10-8 2,0x10-8 2,0x10-8 0, T g, K 0, T g, K 7,0x10-8 6,0x10-8 Ar I nm β, s -1.cm -3 5,0x10-8 4,0x10-8 3,0x10-8 2,0x10-8 1,0x10-8 Van der Waals Lennard-Jones Kaulakys Kaulakys v 0, T g, K 22

23 Influence of Мaxwellian averaging of the broadening cross section on the n*-dependence of the broadening coefficient 7,0x10-8 6,0x10-8 β = 2vσ ( v) v ' β, s -1.cm 3 5,0x10-8 4,0x10-8 3,0x10-8 β = 2 v σ ' ( v ) 2,0x10-8 1,0x10-8 0, n* Christova M Journal of Physics: Conference Series

24 Pressure and gas temperature dependence of the broadening of Ar I nm γ, s -1 2,5x ,0x ,5x ,0x10 10 W L-J K β.10-9, cm 3.s W L-J K 5,0x , p, Torr T g, K T g = 300 K p =50Torr 24

25 Axial variation of the electron density n e, cm λst n e z, mm p =1atm, Tg = 1600 K Ar I , и nm n e 3 Ar I lines 2 Ar I nm; Hβ 3.1 Griem, 3.2 Gigosos 25 λst n e λ 2/3 St n e λ nm g Åcm 3 grad z n e cm

26 Hvala 26