## A fully-neoclassical finite-orbit-width version of the CQL3D Fokker–Planck code

## Abstract

The time-dependent bounce-averaged CQL3D flux-conservative finite-difference Fokker–Planck equation (FPE) solver has been upgraded to include finite-orbit-width (FOW) capabilities which are necessary for an accurate description of neoclassical transport, losses to the walls, and transfer of particles, momentum, and heat to the scrape-off layer. The FOW modifications are implemented in the formulation of the neutral beam source, collision operator, RF quasilinear diffusion operator, and in synthetic particle diagnostics. The collisional neoclassical radial transport appears naturally in the FOW version due to the orbit-averaging of local collision coefficients coupled with transformation coefficients from local (R, Z) coordinates along each guiding-center orbit to the corresponding midplane computational coordinates, where the FPE is solved. In a similar way, the local quasilinear RF diffusion terms give rise to additional radial transport of orbits. We note that the neoclassical results are obtained for ‘full’ orbits, not dependent on a common small orbit-width approximation. Results of validation tests for the FOW version are also presented.

- Authors:

- CompX, Del Mar, CA (United States)

- Publication Date:

- Research Org.:
- CompX, Del Mar, CA (United States)

- Sponsoring Org.:
- USDOE Office of Fossil Energy (FE); USDOE Office of Science (SC)

- OSTI Identifier:
- 1322416

- Alternate Identifier(s):
- OSTI ID: 1322417; OSTI ID: 1425971

- Grant/Contract Number:
- FG02-04ER54744; SC0006614; FC02-01ER54649

- Resource Type:
- Published Article

- Journal Name:
- Plasma Physics and Controlled Fusion

- Additional Journal Information:
- Journal Volume: 58; Journal Issue: 11; Journal ID: ISSN 0741-3335

- Publisher:
- IOP Science

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Fokker–Planck, bounce-averaged, finite-orbit-width, finite-difference

### Citation Formats

```
Petrov, Yu V., and Harvey, R. W. A fully-neoclassical finite-orbit-width version of the CQL3D Fokker–Planck code. United States: N. p., 2016.
Web. doi:10.1088/0741-3335/58/11/115001.
```

```
Petrov, Yu V., & Harvey, R. W. A fully-neoclassical finite-orbit-width version of the CQL3D Fokker–Planck code. United States. doi:10.1088/0741-3335/58/11/115001.
```

```
Petrov, Yu V., and Harvey, R. W. Thu .
"A fully-neoclassical finite-orbit-width version of the CQL3D Fokker–Planck code". United States. doi:10.1088/0741-3335/58/11/115001.
```

```
@article{osti_1322416,
```

title = {A fully-neoclassical finite-orbit-width version of the CQL3D Fokker–Planck code},

author = {Petrov, Yu V. and Harvey, R. W.},

abstractNote = {The time-dependent bounce-averaged CQL3D flux-conservative finite-difference Fokker–Planck equation (FPE) solver has been upgraded to include finite-orbit-width (FOW) capabilities which are necessary for an accurate description of neoclassical transport, losses to the walls, and transfer of particles, momentum, and heat to the scrape-off layer. The FOW modifications are implemented in the formulation of the neutral beam source, collision operator, RF quasilinear diffusion operator, and in synthetic particle diagnostics. The collisional neoclassical radial transport appears naturally in the FOW version due to the orbit-averaging of local collision coefficients coupled with transformation coefficients from local (R, Z) coordinates along each guiding-center orbit to the corresponding midplane computational coordinates, where the FPE is solved. In a similar way, the local quasilinear RF diffusion terms give rise to additional radial transport of orbits. We note that the neoclassical results are obtained for ‘full’ orbits, not dependent on a common small orbit-width approximation. Results of validation tests for the FOW version are also presented.},

doi = {10.1088/0741-3335/58/11/115001},

journal = {Plasma Physics and Controlled Fusion},

number = 11,

volume = 58,

place = {United States},

year = {2016},

month = {9}

}

DOI: 10.1088/0741-3335/58/11/115001

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