Blar i forfatter "Ahmed, Sajidah"

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    • Intermittent fluctuations in the boundary of magnetically confined fusion plasmas 

      Ahmed, Sajidah (Doctoral thesis; Doktorgradsavhandling, 2023-10-09)
      Fluctuation-induced transport in the form of hot and dense blob-like filaments is a profound concern for the successful operation of commercially-viable fusion reactors. These turbulent phenomena are inherent in the scrape-off layer (SOL), a region of magnetic field lines intersecting with the material surfaces. These filaments propagate radially outward leading to damaging plasma-wall interaction ...

    • Reconstruction of intermittent time series as a superposition of pulses 

      Ahmed, Sajidah; Garcia, Odd Erik; Theodorsen, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05)
      Fluctuations in a vast range of physical systems can be described as a superposition of uncorrelated pulses with a fixed shape, a process commonly referred to as a (generalized) shot noise or a filtered Poisson process. In this paper, we present a systematic study of a deconvolution method to estimate the arrival times and amplitudes of the pulses from realizations of such processes. The method shows ...

    • Strongly intermittent far scrape-off layer fluctuations in Alcator C-Mod plasmas close to the empirical discharge density limit 

      Ahmed, Sajidah; Garcia, Odd Erik; Q Kuang, Adam; LaBombard, Brian; L Terry, James; Theodorsen, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-07)
      Intermittent plasma fluctuations in the boundary region of the Alcator C-Mod device were comprehensively investigated using data time-series from gas puff imaging and mirror Langmuir probe diagnostics. Fluctuations were sampled during stationary plasma conditions in ohmically heated, lower single null diverted configurations with scans in both line-averaged density and plasma current, with Greenwald ...