# Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas

## Abstract

This report summarizes major theoretical findings in the linear as well as nonlinear physics of Alfvén waves and energetic particles in magnetically confined fusion plasmas. On the linear physics, a variational formulation, based on the separation of singular and regular spatial scales, for drift-Alfvén instabilities excited by energetic particles is established. This variational formulation is then applied to derive the general fishbone-like dispersion relations corresponding to the various Alfvén eigenmodes and energetic-particle modes. It is further employed to explore in depth the low-frequency Alfvén eigenmodes and demonstrate the non-perturbative nature of the energetic particles. On the nonlinear physics, new novel findings are obtained on both the nonlinear wave-wave interactions and nonlinear wave-energetic particle interactions. It is demonstrated that both the energetic particles and the fine radial mode structures could qualitatively affect the nonlinear evolution of Alfvén eigenmodes. Meanwhile, a theoretical approach based on the Dyson equation is developed to treat self-consistently the nonlinear interactions between Alfvén waves and energetic particles, and is then applied to explain simulation results of energetic-particle modes. Relevant list of journal publications on the above findings is also included.

- Authors:

- Univ. of California, Irvine, CA (United States)

- Publication Date:

- Research Org.:
- Univ. of California, Irvine, CA (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)

- OSTI Identifier:
- 1414294

- Report Number(s):
- DOE-UCI-10417

- DOE Contract Number:
- SC0010417

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Alfven instabilities; energetic particles; tokamak

### Citation Formats

```
Chen, Liu.
```*Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas*. United States: N. p., 2017.
Web. doi:10.2172/1414294.

```
Chen, Liu.
```*Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas*. United States. doi:10.2172/1414294.

```
Chen, Liu. Wed .
"Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas". United States. doi:10.2172/1414294. https://www.osti.gov/servlets/purl/1414294.
```

```
@article{osti_1414294,
```

title = {Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas},

author = {Chen, Liu},

abstractNote = {This report summarizes major theoretical findings in the linear as well as nonlinear physics of Alfvén waves and energetic particles in magnetically confined fusion plasmas. On the linear physics, a variational formulation, based on the separation of singular and regular spatial scales, for drift-Alfvén instabilities excited by energetic particles is established. This variational formulation is then applied to derive the general fishbone-like dispersion relations corresponding to the various Alfvén eigenmodes and energetic-particle modes. It is further employed to explore in depth the low-frequency Alfvén eigenmodes and demonstrate the non-perturbative nature of the energetic particles. On the nonlinear physics, new novel findings are obtained on both the nonlinear wave-wave interactions and nonlinear wave-energetic particle interactions. It is demonstrated that both the energetic particles and the fine radial mode structures could qualitatively affect the nonlinear evolution of Alfvén eigenmodes. Meanwhile, a theoretical approach based on the Dyson equation is developed to treat self-consistently the nonlinear interactions between Alfvén waves and energetic particles, and is then applied to explain simulation results of energetic-particle modes. Relevant list of journal publications on the above findings is also included.},

doi = {10.2172/1414294},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2017},

month = {12}

}