Nonlinear categorization of the energetic-beam-driven instability with drag and diffusion

Lesur, M.*; 井戸村 泰宏

Nuclear Fusion, 52(9), p.094004_1 - 094004_11, 2011/09

https://doi.org/10.1088/0029-5515/52/9/094004

The Berk-Breizman (BB) extension of the bump-on-tail instability includes a finite, fixed wave damping, and a collision operator with drag and diffusion. The BB model is applied to a one-dimensional plasma, to investigate the kinetic nonlinearities, which arise from the resonance of a single electrostatic wave with an energetic-particle beam. For a fixed value of the linear drive, the long-time nonlinear evolution is systematically categorized as damped, steady-state, periodic, chaotic and chirping. The presence of drag and diffusion (instead of a Krook model) qualitatively modifies the nonlinear bifurcations. Nonlinear instabilities are found in both subcritical and barely unstable regimes.

Spectroscopic determination of kinetic parameters for frequency sweeping Alfvn eigenmodes

Lesur, M.*; 井戸村 泰宏; 篠原 孝司; Garbet, X.*; JT-60チーム

Physics of Plasmas, 17(12), p.122311_1 - 122311_9, 2010/12

https://doi.org/10.1063/1.3500224

We present a new method for analyzing fundamental kinetic plasma parameters, such as the linear drive and the external damping rate, based on experimental observations of chirping Alfvn eigenmodes. The method consists of fitting procedures of nonlinear chirping characteristics between the so-called Berk-Breizman model and the experiment, in a quasi-periodic chirping regime. This is the first method that does not require any internal diagnostics. The method is validated through comparisons of kinetic plasma parameters against former analyses of the Toroidicity induced Alfvn Eigenmode (TAE) on MAST. This approach is applied to the TAE on JT-60U, which yields an estimation of the kinetic parameters and suggests the existence of marginally unstable TAEs.

Kinetic simulations of electrostatic plasma waves using Cubic-Interpolated-Propagation scheme

Lesur, M.*; 井戸村 泰宏; 徳田 伸二

JAEA-Research 2006-089, 29 Pages, 2007/01

JAEA-Research-2006-089.pdf:1.67MB

電子プラズマにおける小振幅波動の運動論的特性をVlasov-Poisson方程式系に基づく解析計算及び数値計算によって調べた。Maxwellianプラズマにおけるプラズマ波の分散関係をLaplace-Fourier変換によって解析し、プラズマ波がLandau減衰によって減衰することを示した。Vlasov-Poisson方程式系を位相空間において解き進めるシミュレーションコードをCIP法を用いて開発しLandau減衰の数値計算に成功した。これらの解析的及び数値的手法を適用してビーム成分を伴う電子プラズマの安定性を議論した。

Nonlinear features of the energetic beam-driven instability

Lesur, M.*; 井戸村 泰宏; Garbet, X.*

no journal, , 

燃焼プラズマにおける高エネルギー粒子が励起するアルヴェン波の簡約化問題として知られている外部減衰効果と散逸項を伴う高エネルギービーム駆動不安定性の運動論的プラズマシミュレーションを行い、その非線形発展を簡約化理論モデルと比較した。

The Energetic beam-driven instability, kinetic nonlinearities and subcritical instability in JT-60U

Lesur, M.*; 井戸村 泰宏; 篠原 孝司; Garbet, X.*

no journal, , 

To investigate instabilities driven by high-energy particles in a fusion plasma, we apply the so-called Berk-Breizman model, which is an augmentation of the 1D Vlasov-Poisson system including distribution relaxation and extrinsic damping. The nonlinear evolution of numerical solutions featuring frequency sweeping is compared with JT-60U experiments. Similarities between simulation and experiment is found in the subcritical regime.

Estimation of kinetic parameters based on chirping Alfen eigenmodes

Lesur, M.*; 井戸村 泰宏; 篠原 孝司; Garbet, X.*

no journal, , 

We present a new method for analyzing fundamental kinetic plasma parameters such as the linear drive and the external damping rate based on experimental observations of chirping Alfvn eigenmodes. The method consists of fitting procedures of nonlinear chirping characteristics between the so-called Berk-Breizman (BB) model and the experiment. The method is validated through comparisons of kinetic plasma parameters against former analyses on the toroidicity induced Alfvn eigenmode on MAST. We focus on the dissipation mechanism of a chirping phase-space structure.

Spectroscopic determination of kinetic parameters for frequency sweeping Alfvn eigenmodes

Lesur, M.*; 井戸村 泰宏; 篠原 孝司; Garbet, X.*

no journal, , 

We present a new method for analyzing fundamental kinetic plasma parameters such as the linear drive and the external damping rate based on experimental observations of chirping Alfvn eigenmodes. The method consists of fitting procedures of nonlinear chirping characteristics between the so-called Berk-Breizman model and the experiment. The method is validated through comparisons of trapped particle bounce frequency against former analyses on the Toroidicity-induced Alfvn Eigenmode (TAE) on MAST. The method is applied to JT-60, suggesting the existence of marginally unstable TAEs.