TJ-II:Fast camera: Difference between revisions

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[[File:camaras1.png]]
[[File:camaras1.png]]
[[File:camaras2.png]]
[[File:camaras2.png|700px|]]


== Image Intensifier for Fast Camera==
== Image Intensifier for Fast Camera==
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Below are some examples of movies recorded with the fast camera system of TJ-II. Click on the images to see the corresponding movie.
Below are some examples of movies recorded with the fast camera system of TJ-II. Click on the images to see the corresponding movie.


=== Double imaging to visualize the fine structure of Blobs===
=== Double imaging to visualize the fine structure of Blobs<ref name="delaCal2"></ref>===


[[File:Double_Imaging.jpg|300px|link=http://www-fusion.ciemat.es/fileshare/doc_exchange/camaras/video_DOUBLE_IMAGING.mp4]]
[[File:Double_Imaging.jpg|700px|link=http://www-fusion.ciemat.es/fileshare/doc_exchange/camaras/video_DOUBLE_IMAGING.mp4]]


A visible fast camera coupled with an image intensifier was employed to view turbulent coherent plasma structures (Blobs) at the gas plume being puffed through a poloidal limiter. The image intensifier amplifies the light intensity thereby allowing the imaging system to be operated at ultra-short exposure times down to 100 ns.
A visible fast camera coupled with an image intensifier was employed to view turbulent coherent plasma structures (Blobs) at the gas plume being puffed through a poloidal limiter. The image intensifier amplifies the light intensity thereby allowing the imaging system to be operated at ultra-short exposure times down to 100 ns.
To distinguish real physical signal from noise we get two simultaneous images with the same view and compare them. We call this Double Imaging technique and it allowed us to validate the detected blob shape to scales down to a few millimetres, limited by our optical resolution.
To distinguish real physical signal from noise we get two simultaneous images with the same view and compare them. We call this Double Imaging technique and it allowed us to validate the detected blob shape to scales down to a few millimetres, limited by our optical resolution.


=== Double Imaging of two He I lines    #25623===
=== Two-dimensional imaging of n<sub>e</sub> and T<sub>e</sub><ref name="delaCal4"></ref>===


[[File:25623wComm_Photo000001.jpg|300px|link=http://www-fusion.ciemat.es/camaras/25623wComm.avi|Limiter recycling movie]]
[[File:25623wComm_Photo000001.jpg|700px|link=http://www-fusion.ciemat.es/camaras/25623wComm.avi|Limiter recycling movie]]


With He I filters (706 nm and 728 nm) and 75 mm lens. Speed: 16000 fps. Exposure time: 60&mu;s. V: 750 V.
An intensified visible camera looks tangentially at a poloidal limiter where helium recycles, acting as a wide neutral source, and the atomic line emission due to plasma excitation becomes strongly localized there. It includes a bifurcated coherent bundle, each end with a different interference filter to select helium atomic lines, so that two simultaneous filtered images are captured in one single frame. The object of the proposed technique is to apply the well-known helium-beam line-ratio technique to obtain from selected filtered images the two-dimensional (2D) edge plasma n<sub>e</sub> and T<sub>e</sub>.
ECH and NBI plasma with <n<sub>e</sub>>.  Recycling at limiter inserted 25 mm inside the LCFS. Edge Mode Instabilities after density increase with strong crashes and collapse. From the ratio of the filtered lines the <n<sub>e</sub>> and <T<sub>e</sub>> can be obtained [4].


=== Limiter Recycling ===
=== Limiter Recycling ===
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