# Perpendicular diffusion of energetic particles in collisionless plasmas

## Abstract

A fundamental problem in plasma and astrophysics is the interaction between energetic particles and magnetized plasmas. In the current paper, we focus on particle diffusion across the guide magnetic field. It is shown that the perpendicular diffusion coefficient depends only on the parallel diffusion coefficient and the Kubo number. Therefore, one can find four asymptotic limits depending on the values of these two parameters. These regimes are the quasilinear limit, the Kadomtsev and Pogutse limit, the scaling of Rechester and Rosenbluth, and the scaling found by Zybin and Istomin. In the current article, we focus on the Rechester and Rosenbluth scenario because this was not discovered before in the context of collisionless plasmas. Examples and applications are discussed as well. We show that an energy independent ratio of perpendicular and parallel diffusion coefficients can be found and that this ratio can be very small but also close to unity. This is exactly what one observes in the solar wind.

- Authors:

- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

- Publication Date:

- OSTI Identifier:
- 22407978

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASYMPTOTIC SOLUTIONS; COLLISIONLESS PLASMA; DIFFUSION; INTERACTIONS; MAGNETIC FIELDS; PARTICLES; SCALING; SOLAR WIND

### Citation Formats

```
Shalchi, A., E-mail: andreasm4@yahoo.com.
```*Perpendicular diffusion of energetic particles in collisionless plasmas*. United States: N. p., 2015.
Web. doi:10.1063/1.4906359.

```
Shalchi, A., E-mail: andreasm4@yahoo.com.
```*Perpendicular diffusion of energetic particles in collisionless plasmas*. United States. doi:10.1063/1.4906359.

```
Shalchi, A., E-mail: andreasm4@yahoo.com. Thu .
"Perpendicular diffusion of energetic particles in collisionless plasmas". United States.
doi:10.1063/1.4906359.
```

```
@article{osti_22407978,
```

title = {Perpendicular diffusion of energetic particles in collisionless plasmas},

author = {Shalchi, A., E-mail: andreasm4@yahoo.com},

abstractNote = {A fundamental problem in plasma and astrophysics is the interaction between energetic particles and magnetized plasmas. In the current paper, we focus on particle diffusion across the guide magnetic field. It is shown that the perpendicular diffusion coefficient depends only on the parallel diffusion coefficient and the Kubo number. Therefore, one can find four asymptotic limits depending on the values of these two parameters. These regimes are the quasilinear limit, the Kadomtsev and Pogutse limit, the scaling of Rechester and Rosenbluth, and the scaling found by Zybin and Istomin. In the current article, we focus on the Rechester and Rosenbluth scenario because this was not discovered before in the context of collisionless plasmas. Examples and applications are discussed as well. We show that an energy independent ratio of perpendicular and parallel diffusion coefficients can be found and that this ratio can be very small but also close to unity. This is exactly what one observes in the solar wind.},

doi = {10.1063/1.4906359},

journal = {Physics of Plasmas},

number = 1,

volume = 22,

place = {United States},

year = {Thu Jan 15 00:00:00 EST 2015},

month = {Thu Jan 15 00:00:00 EST 2015}

}