# Presentation: 809134

## 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**

## 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)]

- 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)]

**Codes developed at IPP**

## 
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)

**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)

- H. Qin, W. M. Tang, G. Rewoldt, Phys. Plas. **6** 2544 (1999)

- Based on model by

**LIGKA: Linear GyroKinetic **** she****ar Alfven physics**

## 
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)

- 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)

- H. Qin, W. M. Tang, G. Rewoldt, Phys. Plas. **6** 2544 (1999)

- Based on model by

**LIGKA: Linear GyroKinetic **** she****ar Alfven physics**

## LIGKA: Linear GyroKinetic  shear Alfven physics

- JET #42979, t = 10.121s

- LIGKA

- CASTOR

- Benchmark for TAE mode with open gap:
- 		global mode, ballooning structure

- [D. Borba and W. Kerner, J. Comp. Phys.  **153** 101 (1999)]

## Global modes
Anti-ballooning character
Formed at top of TAE gap
Stronger damping than TAE

- Global modes
- Anti-ballooning character
- Formed at top of TAE gap
- Stronger damping than TAE

- Increasingly damped

**LIGKA: Benchmark for KTAE modes**

## Modeled via change in LIGKA code boundary conditions
No vacuum region
Systematically find all stable modes
Including damping rates
Analogous to TAE antenna experiments

- 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)]

**LIGKA: External antenna drive**

## 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

##  [%]

**Asymptotic expansion in A****eff**

**Local approximation for passing particles**

**LIGKA (passing particles only) **

**0.5**

**1**

**1.5**

**2**

**2.5**

**3**

**3.5**

- Aeff ~ mi/mp

**0**

**0.1**

**0.2**

**0.3**

**0.4**

**A. Könies**

-  [%]

- JET #42979, t = 10.121s

**Isotope mass scali****ng ok in hybrid code**

- Local fluid approximation:   Aeff-1/2
- Kinetic model agrees with hybrid model: LIGKA and CAS3D-K

## Comparison with JET experiments 

- PENN: - significant radiative damping 	in the plasma centre
-             - mode structure not TAE-like

## Comparison with PENN results 

- open TAE gap for experimental density profile

- TAE gap closes for modified density profile (within exp. error bars!)

**experimental density profile**
**modified density profile**

## Comparison with PENN results 

- Kinetic effects important if TAE gap closed

- Damping rates increase up to 0.6 % (experiment ~2 %, open gap ~0.25 %)

## # 52206, t=62.9s 

- 2e19

- 2e19

- q - profile

- density  / experimental density profile

**Comparison with JET experiments**** **

## Comparison with JET experiments 

- Z

- R

- ω/ωTAE  = 0.98,   γ/ω = 0.92%

**Comparison with JET experiments**** **

## Comparison with JET experiments 

- 3    3.2   3.4    3.6   3.8

- 4

- Radius [m]

- arbitrary units

-   total perturbation
- (outward midplane)

- 0

**Comparison with JET experiments**** **

- γ/ω = 1.5%

## 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