A Parametric Analysis of Nonlinear Lower Hybrid Effects

Napoli, F.; Castaldo, C.; Cesario, R.; Schettini, Giuseppe

doi:10.1088/1742-6596/401/1/012016

Cited by 6 publications

(16 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a qualitative aspect, the dependence in this regime agrees well with the published works. [21,22] Quantitatively, the present results can additionally show the sensitivities to the parameter through their powers in the equations. For example, ISQM is more sensitive to T e than ICQM in both density limits.…”

Section: Low-pressure Regimementioning

confidence: 55%

“…3, the dependence of growth rates predicted by Eqs. ( 20) and (21) on n e and T e are plotted, together with the corresponding numerical growth rates as verification. The numerical growth rate of a decay channel indicates the peak growth rate of the corresponding unstable region similar to that shown in Fig.…”

Section: Low-pressure Regimementioning

confidence: 99%

“…Since an increased temperature or a decreased density was found to be able to reduce PIs of the two decay channels, [21,22] inspiring progress has been made in recovering the LHCD efficiency by mitigating PI in recent high-density experiments. Frascati Tokamak Upgrade (FTU) is the first tokamak achieving high-efficiency LHCD in a line-averaged density of 1.5×10 20 m −3 with PIs suppressed through increasing the edge T e .…”

Section: Introductionmentioning

confidence: 99%

“…Besides a lower n e and a higher T e , a lower PI has also been found to be related to a higher magnetic field B 0 , a higher pump frequency ω 0 , and a higher ion mass based on numerical parameter scanning. [21,22] However, it is still hard to apply the existing conclusion to CFETR as the change of the parameter regime can also affect the parameter dependence. For example, the ICQM growth rate for JET-like parameters increases linearly with n e , [22,31] while for FT parameters it increases with n e at a weakening speed.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Parametric decay instabilities of lower hybrid waves on CFETR

Zhou¹,

Xiang²,

Gan³

et al. 2022

Chinese Phys. B

View full text Add to dashboard Cite

The lower hybrid current drive is a potential candidate for sustaining plasma current in tokamak steady state operations, which could be used in China Fusion Engineering Test Reactor (CFETR) with input power up to a few ten megawatts. Such high input power could trigger the well-known parametric instabilities (PIs) at the plasma edge affecting the propagation and absorption of the lower hybrid pump waves, which is studied in this paper. By analyzing the expression of PI growth rates solved from the nonlinear dispersion relation, it is found that the pressure is the key parameter determining the PI characteristics. Ion sound quasi-mode (ISQM) is the dominant decay channel in the low pressure regime, while the ion cyclotron quasi-mode (ICQM), as well as its harmonics, becomes dominant in the intermediate regime. In the high pressure regime, only one mixed channel is found, which is related to Landau damping by free-streaming ions. Analytical expressions of growth rates of these decay channels are also obtained to show the parameter dependences at different pressure limits. The above analytical results are used to estimate the PIs on a typical profile of CFETR, and verified by corresponding numerical calculations. ICQM is found to be the strongest decay channel with a considerable growth rate for CFETR.

show abstract

Section: Low-pressure Regimementioning

confidence: 55%

Section: Low-pressure Regimementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Parametric decay instabilities of lower hybrid waves on CFETR

Zhou¹,

Xiang²,

Gan³

et al. 2022

Chinese Phys. B

View full text Add to dashboard Cite

show abstract

“…However, there are still some unsolved problems for LH waves in fusion plasmas such as 'density limit' [5] and 'spectral gap' [6], which are considered to be related with nonlinear physics. For example, parametric decay instabilities of LH waves have been observed in some experiments [7][8][9][10][11]. Particle-in-cell (PIC) simulation approach is a powerful tool for studying the nonlinear physics of LH waves.…”

Section: Introductionmentioning

confidence: 99%

Global particle simulation of lower hybrid wave propagation and mode conversion in tokamaks

Bao

Zhang

Kuley

2015

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. Particle-in-cell simulation of lower hybrid (LH) waves in core plasmas is presented with a realistic electron-toion mass ratio in toroidal geometry. Due to the fact that LH waves mainly interact with electrons to drive the current, ion dynamic is described by cold fluid equations for simplicity, while electron dynamic is described by drift kinetic equations. This model could be considered as a new method to study LH waves in tokamak plasmas, which has advantages in nonlinear simulations. The mode conversion between slow and fast waves is observed in the simulation when the accessibility condition is not satisfied, which is consistent with the theory. The poloidal spectrum upshift and broadening effects are observed during LH wave propagation in the toroidal geometry.

show abstract

Parameter study of parametric instabilities during lower hybrid wave injection into tokamaks

Zhao¹,

Gao²

2013

Nucl. Fusion

View full text Add to dashboard Cite

A parameter study of the parametric instability (PI) during lower hybrid wave injection into tokamak plasmas is performed based on its local dispersion relation. The drift kinetic model and the fluid model are employed, where both the E × B and E∥ coupling terms are retained. The E∥ coupling term is significant at a lower plasma density ne or a smaller oblique angle δ1 and then influences the density dependence of the PI. At a lower ne the PI decaying into the ion sound quasimode (ISQM) dominates, while at a higher ne the dominant PI is that decaying into the ion cyclotron quasimode (ICQM). A higher electron temperature Te can diminish the PI growth rate for both ISQM and ICQM types, since an increasing Te weakens the PI driving term, just like turning down the injecting power. A large background magnetic field B0 may reduce the PI growth rate, but this effect is rather weak on the ISQM-type PI at a lower ne.

show abstract

A Parametric Analysis of Nonlinear Lower Hybrid Effects

Cited by 6 publications

References 13 publications

Parametric decay instabilities of lower hybrid waves on CFETR

Parametric decay instabilities of lower hybrid waves on CFETR

Global particle simulation of lower hybrid wave propagation and mode conversion in tokamaks

Parameter study of parametric instabilities during lower hybrid wave injection into tokamaks

Contact Info

Product

Resources

About