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Statistical properties of the scrape-off layer (SOL) plasma fluctuations arestudied in ohmically heated plasmas in the Alcator C-Mod tokamak. For the firsttime, plasma fluctuations as well as parameters that describe the fluctuationsare compared across measurements from a mirror Langmuir probe (MLP) and fromgas-puff imaging (GPI) that sample the same plasma discharge. This comparisonis complemented by an analysis of line emission time-series data, synthesizedfrom the MLP electron density and temperature measurements. The fluctuationsobserved by the MLP and GPI typically display relative fluctuation amplitudesof order unity together with positively skewed and flattened probabilitydensity functions. Such data time series are well described by an establishedstochastic framework which model the data as a superposition of uncorrelated,two-sided exponential pulses. The most important parameter of the process isthe intermittency parameter, {\gamma} = {\tau}d / {\tau}w where {\tau}d denotesthe duration time of a single pulse and {\tau}w gives the average waiting timebetween consecutive pulses. Here we show, using a new deconvolution method,that these parameters can be consistently estimated from different statisticsof the data. We also show that the statistical properties of the data sampledby the MLP and GPI diagnostic are very similar. Finally, a comparison of theGPI signal to the synthetic line-emission time series suggests that themeasured emission intensity can not be explained solely by a simplified modelwhich neglects neutral particle dynamics.

Comparison between mirror Langmuir probe and gas puff imaging measurements of intermittent fluctuations in the Alcator C-Mod scrape-off layer