Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fluctuation statistics in the scrape-off layer of Alcator C-Mod   We study long time series of the ion saturation current and floating
potential, sampled by Langmuir probes dwelled in the outboard mid-plane scrape
off layer and embedded in the lower divertor baffle of Alcator C-Mod. A series
of ohmically heated L-mode plasma discharges is investigated with line-averaged
plasma density ranging from n_e/n_G = 0.15 to 0.42, where n_G is the Greenwald
density.
  All ion saturation current time series that are sampled in the far scrape-off
layer are characterized by large-amplitude burst events. Coefficients of
skewness and excess kurtosis of the time series obey a quadratic relationship
and their histograms coincide partially upon proper normalization. Histograms
of the ion saturation current time series are found to agree well with a
prediction of a stochastic model for the particle density fluctuations in
scrape-off layer plasmas.
  The distribution of the waiting times between successive large-amplitude
burst events and of the burst amplitudes are approximately described by
exponential distributions. The average waiting time and burst amplitude are
found to vary weakly with the line-averaged plasma density.
  Conditional averaging reveals that the radial blob velocity, estimated from
floating potential measurements, increases with the normalized burst amplitude
in the outboard mid-plane scrape-off layer. For low density discharges, the
conditionally averaged waveform of the floating potential associated with large
amplitude bursts at the divertor probes has a dipolar shape. In detached
divertor conditions the average waveform is random, indicating electrical
disconnection of blobs from the sheaths at the divertor targets.

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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: math
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg