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TJ-II:Fast camera: Difference between revisions
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The latest upgrade and experiments with the ITER like Wall (ILW) are described elsewhere <ref name="delacal5">[http://ocs.ciemat.es/epsicpp2012pap/pdf/P5.041.pdf E. de la Cal et al et al, ''The Visible Intensified Fast Camera with Wide-angle view of JET ILW experiment'', 39th EPS Conference & 16th Int. Congress on Plasma Physics P5.041]</ref>. | The latest upgrade and experiments with the ITER like Wall (ILW) are described elsewhere <ref name="delacal5">[http://ocs.ciemat.es/epsicpp2012pap/pdf/P5.041.pdf E. de la Cal et al et al, ''The Visible Intensified Fast Camera with Wide-angle view of JET ILW experiment'', 39th EPS Conference & 16th Int. Congress on Plasma Physics P5.041]</ref>. | ||
== Cameras == | == Cameras == | ||
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[[File:camaras1.png]] | [[File:camaras1.png]] | ||
[[File:camaras2.png|500px|]] | [[File:camaras2.png|500px|]] | ||
== Image Intensifier for Fast Camera== | == Image Intensifier for Fast Camera== | ||
The coupling of an image intensifier to a High-speed camera is not trivial, since relatively high light intensity fluxes, sufficient for short exposure times down to the µs range, are captured continuously for a long time period, typically of up to some seconds. As is well known, imageintensifiers (as photomultipliers) are vulnerable to this combination and if not operated correctly, they can be damaged. Moreover, not only the amplification factor is important, but also the image quality and the responselinearity. | The coupling of an image intensifier to a High-speed camera is not trivial, since relatively high light intensity fluxes, sufficient for short exposure times down to the µs range, are captured continuously for a long time period, typically of up to some seconds. As is well known, imageintensifiers (as photomultipliers) are vulnerable to this combination and if not operated correctly, they can be damaged. Moreover, not only the amplification factor is important, but also the image quality and the responselinearity. | ||
Two Hamamatsu image intensifiers (C9548-03BL and C10880) [http://www.hamamatsu.com/resources/pdf/etd/GateII_TII0006E.pdf] were tested and are successfully operated. They are two stage intensifier, including a first GEN II stage with a fast phosphor (P-46) and gain adjustable via the voltage at the MCP, and a second GEN I one (booster) with a fixed gain of 50. Both stages are optically coupled by a Fiber Optic Plate (FOP) which transfers the output signal from the first to the second. Their linear response is guaranteed up to 200000 fps speed. | Two Hamamatsu image intensifiers (C9548-03BL and C10880) [http://www.hamamatsu.com/resources/pdf/etd/GateII_TII0006E.pdf] were tested and are successfully operated. They are two stage intensifier, including a first GEN II stage with a fast phosphor (P-46) and gain adjustable via the voltage at the MCP, and a second GEN I one (booster) with a fixed gain of 50. Both stages are optically coupled by a Fiber Optic Plate (FOP) which transfers the output signal from the first to the second. Their linear response is guaranteed up to 200000 fps speed. | ||
[[File:TJ-II_Fast_camera_diagram.jpg|800px|thumb|center|Schematic diagram of the TJ-II fast camera installation]] | [[File:TJ-II_Fast_camera_diagram.jpg|800px|thumb|center|Schematic diagram of the TJ-II fast camera installation]] | ||
== Videos == | == Videos == | ||
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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. | ||
Some of them contain Audio. | Some of them contain Audio. | ||
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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. | ||
=== Two-dimensional imaging of n<sub>e</sub> and T<sub>e</sub> showing ELM-like Edge Bursts<ref name="delaCal4"> </ref>=== | === Two-dimensional imaging of n<sub>e</sub> and T<sub>e</sub> showing ELM-like Edge Bursts<ref name="delaCal4"> </ref>=== | ||
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[[File:Polvo1b.jpg|300px|link=media:Polvo1b.gif|Dust movie]] | [[File:Polvo1b.jpg|300px|link=media:Polvo1b.gif|Dust movie]] | ||
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The JET wide-angle view Fast Camera has been upgraded with an image intensifier for light amplification and a filter wheel. The objective was to track fast events down to the microsecond range without filtering and to image atomic emission at a speed so as to resolve Edge Localised Modes (ELM), disruptions, pellet injection or plasma breakdown. | The JET wide-angle view Fast Camera has been upgraded with an image intensifier for light amplification and a filter wheel. The objective was to track fast events down to the microsecond range without filtering and to image atomic emission at a speed so as to resolve Edge Localised Modes (ELM), disruptions, pellet injection or plasma breakdown. | ||
== References == | == References == | ||
<references /> | <references /> | ||