# Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on B_T

## Abstract

This paper presents investigations on the role of the edge ion heat flux for transitions from L-mode to H-mode in Alcator C-Mod. Previous results from the ASDEX Upgrade tokamak indicated that a critical value of edge ion heat flux per particle is needed for the transition. Analysis of C-Mod data confirms this result. The edge ion heat flux is indeed found to increase linearly with density at given magnetic field and plasma current. Furthermore, the Alcator C-Mod data indicate that the edge ion heat flux at the L-H transition also increases with magnetic field. Combining the data from Alcator C-Mod and ASDEX Upgrade yields a general expression for the edge ion heat flux at the L-H transition. These results are discussed from the point of view of the possible physics mechanism of the L-H transition. They are also compared to the L-H power threshold scaling and an extrapolation for ITER is given.

- Authors:

- Publication Date:

- DOE Contract Number:
- FC02-99ER54512; SC0014264

- Research Org.:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

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

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

- OSTI Identifier:
- 1878757

- DOI:
- https://doi.org/10.7910/DVN/FSSICO

### Citation Formats

```
Schmidtmayr, M., Hughes, J. W., Ryter, F., Wolfrum, E., Cao, N., Creely, A. J., Howard, N., Hubbard, A. E., Lin, Y., Reinke, M. L., Rice, J. E., Tolman, E. A., Wukitch, S., Ma, Y., ASDEX Upgrade Team, and Alcator C-Mod Team.
```*Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on B_T*. United States: N. p., 2018.
Web. doi:10.7910/DVN/FSSICO.

```
Schmidtmayr, M., Hughes, J. W., Ryter, F., Wolfrum, E., Cao, N., Creely, A. J., Howard, N., Hubbard, A. E., Lin, Y., Reinke, M. L., Rice, J. E., Tolman, E. A., Wukitch, S., Ma, Y., ASDEX Upgrade Team, & Alcator C-Mod Team.
```*Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on B_T*. United States. doi:https://doi.org/10.7910/DVN/FSSICO

```
Schmidtmayr, M., Hughes, J. W., Ryter, F., Wolfrum, E., Cao, N., Creely, A. J., Howard, N., Hubbard, A. E., Lin, Y., Reinke, M. L., Rice, J. E., Tolman, E. A., Wukitch, S., Ma, Y., ASDEX Upgrade Team, and Alcator C-Mod Team. 2018.
"Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on B_T". United States. doi:https://doi.org/10.7910/DVN/FSSICO. https://www.osti.gov/servlets/purl/1878757. Pub date:Thu Oct 04 00:00:00 EDT 2018
```

```
@article{osti_1878757,
```

title = {Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on B_T},

author = {Schmidtmayr, M. and Hughes, J. W. and Ryter, F. and Wolfrum, E. and Cao, N. and Creely, A. J. and Howard, N. and Hubbard, A. E. and Lin, Y. and Reinke, M. L. and Rice, J. E. and Tolman, E. A. and Wukitch, S. and Ma, Y. and ASDEX Upgrade Team and Alcator C-Mod Team},

abstractNote = {This paper presents investigations on the role of the edge ion heat flux for transitions from L-mode to H-mode in Alcator C-Mod. Previous results from the ASDEX Upgrade tokamak indicated that a critical value of edge ion heat flux per particle is needed for the transition. Analysis of C-Mod data confirms this result. The edge ion heat flux is indeed found to increase linearly with density at given magnetic field and plasma current. Furthermore, the Alcator C-Mod data indicate that the edge ion heat flux at the L-H transition also increases with magnetic field. Combining the data from Alcator C-Mod and ASDEX Upgrade yields a general expression for the edge ion heat flux at the L-H transition. These results are discussed from the point of view of the possible physics mechanism of the L-H transition. They are also compared to the L-H power threshold scaling and an extrapolation for ITER is given.},

doi = {10.7910/DVN/FSSICO},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2018},

month = {10}

}

Works referencing / citing this record:

##
Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on *B* _{T}

journal, March 2018

- Schmidtmayr, M.; Hughes, J. W.; Ryter, F.
- Nuclear Fusion, Vol. 58, Issue 5