## Abstract

Statistical analysis of the ion flux to the JET outer-wall is conducted in outer-wall limiter mounted Langmuir probe (OLP) time-series across a wide range of plasma current and line-averaged density during Ohmically heated horizontal target L-mode plasmas. The mean, μ, and the standard deviation, σ, of the ion-saturation current measured by the OLP show systematic variation with plasma current and density. Both increase as either plasma current decreases and/or density increases. Upon renormalization, achieved by subtraction of μ and rescaling by σ, the probability distribution functions (PDFs) of each signal collapse approximately onto a single curve. The shape of the curve deviates from a Γ distribution in the tail of the PDF and is better described by a log-normal distribution. The invariance in the shape of the PDF, which occurs over approximately four decades of the ordinate, is shown to be the result of a balance between the duration time of the average burst wave-form, τ_{d} and the waiting time between bursts, τ_{w}. This implies that the intermittency parameter, τ_{d}/τ_{w} , can be considered constant at the JET outer wall during horizontal target Ohmic L-mode operation. This result may be important both for model validation and prediction.

Original language | English |
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Article number | 036016 |

Number of pages | 7 |

Journal | Nuclear Fusion |

Volume | 57 |

Issue number | 3 |

DOIs | |

Publication status | Published - 11 Jan 2017 |

### Bibliographical note

© 2017 Culham Centre for Fusion Energy. This is an author-produced version of a paper accepted for publication. Uploaded with permission of the publisher/copyright holder. Further copying may not be permitted; contact the publisher for details## Keywords

- Langmuir probe
- Ohmically heated
- plasma wall flux