Gyrokinetic simulation of low-frequency Alfvénic modes in DIII-D tokamak

Choi, Gyungjin; Liu, Pengfei; Wei, Xiyang; Nicolau, J. H.; Dong, Ge; Zhang, Wenlu; Zhang, Lin; Heidbrink, W. W.; Hahm, Tae Soo

doi:10.1088/1741-4326/abf0dd

Cited by 19 publications

(24 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, GTC has also incorporated compressible magnetic perturbations to maintain perpendicular force balance [29], which have been neglected in most of the previous gyrokinetic simulations. Recent GTC simulations found that these compressible magnetic perturbations can be important for interchange-like modes [29,30] with realistic β (ratio of kinetic pressure to magnetic pressure) in tokamak plasmas, consistent with analytic theory [31,32].…”

Section: Introductionsupporting

confidence: 60%

“…Note that this model incorporates the compressible magnetic perturbation δB to maintain perpendicular force balance. The effects of the compressible magnetic perturbation δB , which have been neglected in most of gyrokinetic simulations, can be very important even for modest beta when simulating low frequency MHD modes such as interchange and kink instabilities for realistic β in existing and future tokamak plasmas [30][31][32]44]. The same argument also holds for a broad class of long wavelength drift-Alfvén waves [55,56].…”

Section: Verification Of Internal Kink Simulations In Ideal Mhd Limitmentioning

confidence: 93%

See 1 more Smart Citation

Verification and validation of linear gyrokinetic and kinetic-MHD simulations for internal kink instability in DIII-D tokamak

Brochard¹,

Bao²,

Liu³

et al. 2022

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

Verification and linear validation of the internal kink instability in tokamak have been performed for both gyrokinetic (GTC) and kinetic-MHD codes (GAM-solver, M3D-C1-K, NOVA, XTOR-K). Using realistic magnetic geometry and plasma profiles from the same equilibrium reconstruction of the DIII-D shot #141216, these codes exhibit excellent agreement for the growth rate and mode structure of the internal kink mode when all kinetic effects are suppressed. The simulated radial mode structures, obtained from linear simulations, are in reasonable agreement with the normalised electron cyclotron emission measurement after adjusting, within the experimental uncertainty, the safety factor q=1 flux-surface location in the equilibrium reconstruction. Compressible magnetic perturbations strongly destabilize the kink, while poloidal variations of the equilibrium current density reduce the growth rate of the kink. Furthermore, kinetic effects of thermal ions are found to decrease the kink growth rate in kinetic-MHD simulations, but increase the kink growth rate in gyrokinetic simulations, due to the additional drive of the ion temperature gradient and parallel electric field. Kinetic thermal electrons are found to have negligible effects on the internal kink instability.

show abstract

Section: Introductionsupporting

confidence: 60%

Section: Verification Of Internal Kink Simulations In Ideal Mhd Limitmentioning

confidence: 93%

Verification and validation of linear gyrokinetic and kinetic-MHD simulations for internal kink instability in DIII-D tokamak

Brochard¹,

Bao²,

Liu³

et al. 2022

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…These include the linear gyrokinetic code LIGKA [63], the ideal MHD code NOVA [64], the gyrokinetic code GTC, and the gyrofluid code FAR3d [65]. The GTC simulations are discussed in detail in [66].…”

Section: Initial Comparisons With Theorymentioning

confidence: 99%

Stability of beta-induced Alfvén eigenmodes (BAE) in DIII-D

et al. 2021

Self Cite

View full text Add to dashboard Cite

Although the stability of ellipticity, toroidal and reversed-shear Alfvén eigenmodes (EAE, TAE, RSAE) are relatively well understood, less is known about the stability of lower-frequency modes such as the beta-induced Alfvén eigenmode (BAE) but, because they are often unstable in present devices and are implicated in fast-ion transport, understanding their stability is vital. BAE stability is studied in primarily weak or reversed shear DIII-D plasmas with sub-Alfvénic deuterium beams. Modes are classified based on electron cyclotron emission, beam emission spectroscopy, magnetics, and interferometer data. The study is limited to the initial two seconds of the discharge, where the evolving q profile provides an effective scan of the dependence of stability upon q. In a dedicated experiment, BAEs are unstable at times in the discharge when the minimum of the safety factor q min is close to a rational number. The observed mode frequencies are usually close to analytic estimates of the BAE accumulation point and the eigenfunction peaks in the vicinity of q min. Unstable BAEs usually occur in bursts that chirp rapidly in frequency. To isolate the importance of thermal and beam gradients in driving the modes, the beam and electron cyclotron heating power is altered for 50–100 ms durations in reproducible discharges. As expected from the resonance condition, BAEs depend sensitively on the beam power and injection geometry. Modes only persist for ∼25 ms because the anisotropic beam population only interacts strongly with the modes over a relatively narrow range of q. A database of over 1000 beam-heated discharges shows that BAEs are more likely to be unstable when the poloidal beta exceeds 0.5.

show abstract

“…The effects of the compressible magnetic perturbation δB , which has been neglected in most of gyrokinetic simulations, can be very important even for modest beta when simulating low frequency MHD modes such as interchange and kink instabilities for realistic β in existing and future tokamak plasmas [31][32][44] [30].…”

Section: Codementioning

confidence: 99%

Verification and validation of gyrokinetic and kinetic-MHD simulations for internal kink instability in DIII-D tokamak

Brochard,

Bao,

Liu

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Verification and validation of the internal kink instability in tokamak have been performed for both gyrokinetic (GTC) and kinetic-MHD codes (GAM-solver, M3D-C1-K, NOVA, XTOR-K). Using realistic magnetic geometry and plasma profiles from the same equilibrium reconstruction of the DIII-D shot #141216, these codes exhibit excellent agreement for the growth rate and mode structure of the internal kink mode when all kinetic effects are suppresed. The simulated radial mode structures agree quantitatively with the electron cyclotron emission measurement after adjusting, within the experimental uncertainty, the safety factor q=1 flux-surface location in the equilibrium reconstruction. Compressible magnetic perturbations strongly destabilize the kink, while poloidal variations of the equilibrium current density reduce the growth rate of the kink. Furthermore, kinetic effects of thermal ions are found to decrease the kink growth rate in kinetic-MHD simulations, but increase the kink growth rate in gyrokinetic simulations, due to the additional drive of the ion temperature gradient and parallel electric field. Kinetic thermal electrons are found to have negligible effects on the internal kink instability.

show abstract

Gyrokinetic simulation of low-frequency Alfvénic modes in DIII-D tokamak

Cited by 19 publications

References 62 publications

Verification and validation of linear gyrokinetic and kinetic-MHD simulations for internal kink instability in DIII-D tokamak

Verification and validation of linear gyrokinetic and kinetic-MHD simulations for internal kink instability in DIII-D tokamak

Stability of beta-induced Alfvén eigenmodes (BAE) in DIII-D

Verification and validation of gyrokinetic and kinetic-MHD simulations for internal kink instability in DIII-D tokamak

Contact Info

Product

Resources

About