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TJ-II:Blobs vs streamers: Difference between revisions
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We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 ⋅ 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like. | We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 ⋅ 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like. | ||
Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and omega_S.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272|Phys. Plasmas, 22:022308, 2015]]</ref> | Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and <math>\omega_S</math>.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272|Phys. Plasmas, 22:022308, 2015]]</ref> | ||
We will also attempt to quantify 'blobbiness', in order to detect the transition between 'blob-type' and 'streamer-type' turbulence. This difference might also be reflected in the radial correlation length (or causality, cf. Transfer Entropy). Perhaps there are other ways to quantify the difference between 'blob-type' and 'streamer-type' turbulence. | We will also attempt to quantify 'blobbiness', in order to detect the transition between 'blob-type' and 'streamer-type' turbulence. This difference might also be reflected in the radial correlation length (or causality, cf. Transfer Entropy). Perhaps there are other ways to quantify the difference between 'blob-type' and 'streamer-type' turbulence. | ||
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== Description of required resources == | == Description of required resources == | ||
Required resources: | Required resources: | ||
* Number of plasma discharges or days of operation: at least 1 | * Number of plasma discharges or days of operation: at least 1 day | ||
* Essential diagnostic systems: Langmuir probe (2-dimensional), biasing probe | * Essential diagnostic systems: Langmuir probe (2-dimensional), biasing probe | ||
* Type of plasmas (heating configuration): ECRH | * Type of plasmas (heating configuration): ECRH | ||
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[[Category:TJ-II internal documents]] | [[Category:TJ-II internal documents]] | ||
[[Category:TJ-II experimental proposals]] | [[Category:TJ-II experimental proposals Spring 2018]] | ||