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LIGKA: a new gyrokinetic code in realistic tokamak geometry with full orbits

LIGKA: a new gyrokinetic code in realistic tokamak geometry with full orbits. S. Günter, P. Lauber , A. K önies, S. Pinches Max-Planck-Institut f ür Plasmaphysik, Garching/Greifswald, Germany D. Testa, A. Fasoli CRPP Lausanne, Switzerland. and comparison with experiment.

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LIGKA: a new gyrokinetic code in realistic tokamak geometry with full orbits

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  1. LIGKA: a new gyrokinetic code in realistic tokamak geometry with full orbits S. Günter, P. Lauber, A. Könies, S. Pinches Max-Planck-Institut für Plasmaphysik, Garching/Greifswald, Germany D. Testa, A. Fasoli CRPP Lausanne, Switzerland and comparison with experiment

  2. Codes developed at IPP • LIGKA • Linear gyrokinetic non-perturbative tokamak model • [Ph. Lauber, Ph.D. Thesis, T.U. München 2003] • CAS3D-K • Linear perturbative drift-kinetic approach for stellarators • [A. Könies, Phys. Plasmas 7 1139 (2000)] • HAGIS • Initial value nonlinear drift-kinetic f model • [S. D. Pinches et al., Comput. Phys. Commun. 111, 131 (1998)]

  3. LIGKA: Linear GyroKinetic shear Alfven physics Based on model by H. Qin, W. M. Tang, G. Rewoldt, Phys. Plas. 6 2544 (1999) • Linear shear Alfven perturbations • Calculates mode frequency, growth rate and mode structure, including FLR effects • Non-perturbative • Allows change from MHD eigenmode structure • Nonlinear eigenvalue problem (Nyquist solver)

  4. LIGKA: Linear GyroKinetic shear Alfven physics Based on model by H. Qin, W. M. Tang, G. Rewoldt, Phys. Plas. 6 2544 (1999) In addition: • Accurate treatment of unperturbed particle orbits • Numerical integration of full drift orbit effects (HAGIS) • General tokamak geometry • From numerical equilibrium code (e.g. HELENA)

  5. LIGKA: Linear GyroKinetic shear Alfven physics Benchmark for TAE mode with open gap: global mode, ballooning structure JET #42979, t = 10.121s CASTOR LIGKA [D. Borba and W. Kerner, J. Comp. Phys. 153 101 (1999)]

  6. p=3 p=2 JET #42979, t = 10.121s 0.75 Electrostatic Potential,  Shear Alfvén Continuum p=1 Frequency [/A] p=3 0.45 p=2 p=0 p=1 0.66 0.84 p=0 Radius Radius 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 LIGKA: Benchmark for KTAE modes • Global modes • Anti-ballooning character • Formed at top of TAE gap • Stronger damping than TAE Increasingly damped

  7. JET #42979, t = 10.121s 20 TAE 18 KTAE 16 p=3 Plasma response 14 p=4 p=2 12 p=1 p=0 10 0.35 0.4 0.45 0.5 0.55 0.6 Frequency [/A] LIGKA: External antenna drive • Modeled via change in LIGKA code boundary conditions • No vacuum region • Systematically find all stable modes • Including damping rates • Analogous to TAE antenna experiments • [Fasoli et al., PRL 76 1067 (1996)] [Conner et al, Proc. 21st EPS Conf., Montpellier, 18B 616 (1996)]

  8. Comparison with JET damping rate experiments • so far: often large discrepancies between measured and calculated damping rates for TAE modes (except for PENN model) • Wrong isotope scaling for fluid model reported Fasoli, Jaun

  9. Isotope mass scaling ok in hybrid code • Local fluid approximation:   Aeff-1/2 • Kinetic model agrees with hybrid model: LIGKA and CAS3D-K JET #42979, t = 10.121s A. Könies 0.4 Local approximation for passing particles Asymptotic expansion in Aeff CAS3D-K (passing particles only) 0.3 LIGKA (passing particles only)  [%] 0.2 0.1 0 0.5 1 1.5 3 3.5 2 2.5 Aeff ~ mi/mp

  10. Testa (2004): experimental mode structure (JET, similar discharge) Comparison with JET experiments PENN: - significant radiative damping in the plasma centre - mode structure not TAE-like

  11. vA= B/ 0 Comparison with PENN results experimental density profile modified density profile open TAE gap for experimental density profile TAE gap closes for modified density profile (within exp. error bars!)

  12. Comparison with PENN results Kinetic effects important if TAE gap closed Damping rates increase up to g/w=0.6 % (experiment ~2 %, open gap ~0.25 %)

  13. 4 3 ω/ωA0 2 1 1 0 0 1 normalised radius temperature: ion / electron [keV] ωTAE =0.340 0.8 0.7 0 normalised radius 1 0 normalised radius Comparison with JET experiments density / experimental density profile 2e19 2e19 q - profile # 52206, t=62.9s

  14. total perturbation (outward midplane) arbitrary units 0 m=1 Radius [m] 3 4 m=2 0 m=3 0 1 normalised radius Comparison with JET experiments Z ω/ωTAE = 0.98, γ/ω = 0.92% R

  15. Comparison with JET experiments total perturbation (outward midplane) arbitrary units 0 3 3.2 3.4 3.6 3.8 4 Radius [m] γ/ω = 1.5% ω/ωTAE = 0.98, γ/ω = 0.92%

  16. Summary and Conclusion • LIGKA: - linear gyrokinetic code with realistic tokamak geometry and fast particle orbits • Agreement between calculated and measured damping rates strongly depends on density profile at the plasma edge (TAE gap open or closed) • Is there a difference between (limiter) discharges with qa being a rational value and not? • Outlook: • Code can deal with energetic particle modes as well (non-perturbative) • Coupling to non-linear HAGIS code • Further comparison with experiments • ITER predictions

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