Kein Folientitel - Max Planck Society

Kein Folientitel - Max Planck Society

Kinetic modeling of multispecies edge plasmas Konstantin Matyash Ph. D. work at Max-Planck IPP, Stellarator theory division, Edge Modeling Group since June 13, 2000 Scientific supervisor: Dr. Ralf Schneider Academic Supervisor: Prof. Dr. Jrgen Nhrenberg Max-Planck-Institut fr Plasmaphysik, EURATOM Association Outline "The goal of scientific computing is insight, not numbers." Richard Hamming Motivation why? Multispecies Particle-in-Cell code with Monte-Carlo Collisions (PIC-MCC) how? Applications of the PIC model what? Summary Max-Planck-Institut fr Plasmaphysik, EURATOM Association Motivation: hydrocarbon plasmas in industry and fusion carbon films deposition for industry tritium codeposition in fusion major topics: chemical erosion tritium codeposition graphite tile P. Coad, JET Max-Planck-Institut fr Plasmaphysik, EURATOM Association

Particle simulations 1943 Hartree, Nicolson: orbits of about 30 interacting electrons, desk calculator 80486 80386 80286 8086 4004 P7 (Merced) P6 (Pentium P5 Pro) (Pentium) Max-Planck-Institut fr Plasmaphysik, EURATOM Association Particle-in-Cell simulation dx v dt dv q E v B dt m E t 1 x 0 E E i

x y 1 1 x y S x 0 qi S x xi x y x x and y y E E Max-Planck-Institut fr Plasmaphysik, EURATOM Association 3D3V PIC-MCC multispecies code multispecies: electrons, ions, neutrals extension to full 3-D MCC collisions T/T0 PIC-MCC analytical 1.0 0.8 ECR heating model with feedback control loop 0.6

simple plasma-surface interaction model 0.4 parallelization for Linux-cluster 0.0 (MPI) 0.2 0 1 2 3 4 5 it Max-Planck-Institut fr Plasmaphysik, EURATOM Association Capacitive RF discharge Collaboration with IEP5, Bochum University (Ivonne Mller) ne ~ 10 -10 cm nn ~ 1015 -1016 cm-3 fRF = 13.56 MHz 9 10 -3 ne = 1010 cm-3, nH2 = 9.21014 cm-3, nCH4 = 71014 cm-3, p = 0.085 Torr (11 Pa) potential Max-Planck-Institut fr Plasmaphysik, EURATOM Association

Capacitive RF discharge electron and CH4+ ion density electrons reach electrode only during sheaths collapse CH4+ ion energy distribution energetic ions at the wall due to acceleration in the sheath Max-Planck-Institut fr Plasmaphysik, EURATOM Association Capacitive RF discharge electron-impact ionization rate electron velocity distribution -3 -1 n'ei , cm c 14 8x10 14 6x10 14 4x10 14 2x10 0 0 32 64 96

128 Y, D energetic electrons oscillate between sheaths ionization spreads over the bulk Max-Planck-Institut fr Plasmaphysik, EURATOM Association Fermi acceleration due to periodic force Cosmic rays - particles with energies 108 - 1020 eV Fermi proposal acceleration due to collisions with moving magnetic fields E. Fermi: On origin of the cosmic radiation, Phys. Rev. 75 (1949) 116 Ulam problem acceleration due to collisions with regularly oscillating wall S.M. Ulam: 4th Berkeley Symp. on Math. Stat. and Probability. University of California Press 3 (1961) 315 xw a sint vw V 0 cost Fermi acceleration due to collisions with regularly oscillating boundary Max-Planck-Institut fr Plasmaphysik, EURATOM Association Fermi acceleration due to periodic force Simplified mapping of the Ulam problem u M.A. Lieberman and A.J. Lichtenberg, Phys. Rev. A 5 (1972) 1852 u un - ball velocity before n-th collision n - phase of the wall oscillation during collision v 2V 0 un 1 un sin n n 1 n

2M un 1 mod 2 L M 2a Stochasticity criterion Phase space for M 2.55 n 5000000 u ub 2M stochastic sea with adiabatic islands, limited above by a regular region 0 Max-Planck-Institut fr Plasmaphysik, EURATOM Association Capacitive RF discharge electron energy probability function experiment simulation 10 11 10 T1 = 0.39 eV, n1 = 10 cm 10 9 T2 = 3 eV, n2 = 10 cm

-3 -3 cm ) 10 -3 9 10 8 10 7 eepf (eV -3/2 10 T2 T1 10 6 0 5 10 15 20 electron energy (eV) V.A. Godyak, et al., Phys. Rev. Lett., 65 (1990) 996.

bi-maxwellian distribution due to stochastic heating Max-Planck-Institut fr Plasmaphysik, EURATOM Association Capacitive RF discharge, high pressure ne = 1010 cm-3, nH2 = 9.21015 cm-3, nCH4 = 71015 cm-3, p = 0.85 Torr (110 Pa) potential field reversal after sheath collapse electron and CH4+ ion density ionization within sheaths Max-Planck-Institut fr Plasmaphysik, EURATOM Association Capacitive RF discharge, high pressure electron velocity distribution electron-impact ionization rate -3 -1 n'ei , cm c 16 1.2x10 16 1.0x10 15 8.0x10 15 6.0x10 15 4.0x10 15

2.0x10 0.0 0 32 64 96 128 Y, D energetic electrons only in sheaths ionization localized in the sheaths Max-Planck-Institut fr Plasmaphysik, EURATOM Association Capacitive RF discharge, high pressure 653.3 nm excitation rate experiment electron-impact ionization rate simulation -3 -1 n'ei , cm c 7E16 6E16 10 4.8E16 Y, mm 8 3.6E16 2.4E16 6

1.2E16 0 4 2 0 0 20 40 60 80 time, ns 100 120 140 C.M.O. Mahony et al., Appl. Phys. Lett. 71 (1997) 608. double peak structure due to sheath reversal Max-Planck-Institut fr Plasmaphysik, EURATOM Association Dusty (complex) plasmas dust particle q ~ 104e R ~ 10-6 m M ~ 10-12 g Lower electrode negative charge due to higher electron mobility levitation in strong sheath electric field

Max-Planck-Institut fr Plasmaphysik, EURATOM Association Experimental investigations of complex plasmas top view side view G E Morfill et al, Plasma Phys. Control. Fusion 44 (2002) B263 Max-Planck-Institut fr Plasmaphysik, EURATOM Association PIC simulation: plasma crystal (2D) supersonic ion flow dust particle as additional species in PIC scheme lower electrode formations of the dust molecules due to focusing of the ion flow Max-Planck-Institut fr Plasmaphysik, EURATOM Association PIC simulation: plasma crystal (2D) potential f, V 6 Y , D 23 f, V 24 4 12.8 12.1 25

11.5 26 2 10.9 10.2 27 9.6 28 00 4 8 8 Y , D 16 12 24 32 16 9.0 8.4 29 7.8 30 31 0 2 4

6 X , D potential determined by sheath and dust 8 10 12 14 16 X , D Y , D Max-Planck-Institut fr Plasmaphysik, EURATOM Association PIC simulation: plasma crystal (2D) vertical ion velocity horizontal ion velocity Y , D 23 uiy , vs 24 1.5 1.4 25 1.3 26 1.2 1.1

27 1.0 28 0.8 0.7 29 0.6 30 31 23 uix , vs 24 0.13 0.10 25 0.07 26 0.03 0 27 -0.03 28 -0.07 -0.10 29 -0.13

30 0 2 4 6 8 10 12 14 31 16 0 2 4 6 X , D wake field effects due to ion flow 8 10 12 14 16 X , D

Y , D Max-Planck-Institut fr Plasmaphysik, EURATOM Association PIC simulation: plasma crystal (2D) ion density electron temperature 23 9 -3 ni , 10 cm 24 2.8 2.5 25 2.3 26 2.1 1.9 27 1.7 28 1.4 1.2 29 1.0 30 31

0 2 4 6 8 10 12 14 16 X , D focusing of the ion flow, dust molecules electron heating in the dust layer Max-Planck-Institut fr Plasmaphysik, EURATOM Association PIC simulation: plasma crystal - full 3D top view quasi-2D structure due to vertical alignment of horizontal layers Max-Planck-Institut fr Plasmaphysik, EURATOM Association Structural analysis of plasma crystal 8 6 Z, D 4

2 0 0 2 4 X, 6 8 D simple hexagonal structure with defects J. B. Pieper, J. Goree, R.A. Quinn, Phys. Rev. 54 (1996) 5636 Max-Planck-Institut fr Plasmaphysik, EURATOM Association Plasma crystal under microgravity on ISS void formed in the middle of discharge under microgravity conditions Sergey Krikalev with ''PKE Nefedov'' onboard of ISS, March 2001 http://www.mpe.mpg.de/pke/ Max-Planck-Institut fr Plasmaphysik, EURATOM Association PIC simulation: plasma crystal under zero gravity 0 4 8 12 Y, D 16

20 24 28 32 0 4 8 X, void formation due to ion drag force 12 D 16 Max-Planck-Institut fr Plasmaphysik, EURATOM Association Particle-in-Cell code applications ECR plasma Parasitic plasma under divertor roof baffle D iv I I b ne ~ 1010 cm-3 nn ~ 1014 cm-3 Te ~ 2 eV Plasma detected below roof baffle of Div IIb Typical parameters: 4*108 < ne < 7*1011 cm-3 5 < Te < 15 eV Scaling: ne ~ Radiation2.7*Particles_flux0.7 in n e r d iv e r to r ro o f b a f f le p la te o u te r

d iv e r to r p la te S i- w a f e r Q M B L a n g m u ir p ro b e Plasma originated by photoionisation or photoeffect ! 10 -3 ne, 10 cm 2.0 Recycling in SOL 1.8 1.6 -3 n, cm 5x10 ne ~ 1013 cm-3 nn ~ 1014 cm-3 Te ~ 10 eV 5x10 1.4 14 1.2 nH nCH nCH nCH nCH nC 13

1.0 0.8 4 0.6 3 5x10 12 5x10 11 0.4 2 0.2 8 32 5x10 10 0 16 32 48 6 Wall 4 24 Y, Ld 64

Y, d 16 2 8 X, Ld Max-Planck-Institut fr Plasmaphysik, EURATOM Association Collaboration projects PIC simulation of a plasma thruster (F. Taccogna, Bari University, Italy) EVDF modeling for RF discharge in a CH4 - H2 mix (I. Mller, Bochum University) EVDF 0 10 9 16 16 -3 16 -3 ne= 2.5*10 , nCH = 1.7*10 , nH = 0.5*10 (cm ) 9 4 16 2 ne= 5.0*10 , nCH = 1.4*10 , nH = 0.9*10 (cm )

-1 10 9 4 16 2 16 -3 ne= 7.5*10 , nCH = 1.15*10 , nH = 1.15*10 (cm ) 10 ne= 10 , -2 10 4 16 2 16 -3 nCH = 1.0*10 , nH = 1.3*10 (cm ) 4 2 -3 10 -4

10 -5 10 -6 10 -7 10 0 5 10 15 20 25 30 E, eV Max-Planck-Institut fr Plasmaphysik, EURATOM Association Collaboration projects Neutral species modeling for RF discharge in a CH4 - H2 mix (A. Serdyuchenko, Bochum University) -3 n, cm 10 15 10 13

9 -3 ne = 10 cm , Te = 1 ev, = 47 ms, p = 100 pa H2 CH4 C2H4 H C2H6 C2H2 10 9 10 7 C2H5 -4 10 10 -3 10 -2 -1 10 10 0 10 / eTe 4

0 0 0 30 0 60 0 70 0 80 0 89 0 89.9 0 90 3 2 1 0 11 10 Probe floating potential dependence on magnetic field tilt (B. Koch, IPP, Berlin) 1 10 2 CH3 -1 C2H3 -2 C2H

-3 t, s 0 10 20 30 40 50 X, d Max-Planck-Institut fr Plasmaphysik, EURATOM Association Collaboration projects Simulation of ion energy distribution (V. Vartolomei, Greifswald University) IED, a.u. phi, a.u. 5 X, cm 4 13.5 0 2.5 5 10 3 13.0 12.5 2

12.0 1 0 Simulation of rotating dust cloud (M. Frhlich, Greifswald University) 11.5 0 5 10 15 20 25 E, eV 30 35 40 45 50 0 1 2 3 4 5 6 7

8 0 1 2 3 4 5 6 8 7 3D electrostatic PIC-MCC code for multispecies plasmas capacitive RF discharge K. Matyash and R. Schneider, Contributions to Plasma Physics, in press dusty plasma, plasma crystal K. Matyash and R. Schneider, Contributions to Plasma Physics, in press ECR plasma in Plato: +0D chemical kinetic model, B2-Eirene fluid model K. Matyash, R. Schneider, A. Bergmann, W. Jacob, U. Fantz and P. Pecher, J. Nucl. Mater. 313-316 (2003) 434 K. Matyash, R. Schneider, A. Bergmann, W. Jacob, U. Fantz, P. Pecher, Czech. J. of Phys. 52 D (2002) 515 scrape-off layer plasma R. Schneider, X. Bonnin, N. McTaggart, A. Runov, M. Borchardt, J. Riemann, A. Mutzke, K. Matyash, H. Leyh, M. Warrier, D. Coster, W. Eckstein, R. Dohmen, Contributions to Plasma Physics, in press photon created plasma collaboration projects

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