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TJ-II: Commissioning of new Gas Puff Imaging system

2021-01-22T10:56:02Z

E.delacal: Created page with "== Experimental campaign == 2021 == Proposal title == '''Commissioning of new Gas Puff Imaging (GPI) system''' == Name and affiliation of proponent == I. Voldiner,E. de la C..."

== Experimental campaign ==
2021

== Proposal title ==
'''Commissioning of new Gas Puff Imaging (GPI) system'''

== Name and affiliation of proponent ==
I. Voldiner,E. de la Cal, B. van Milligen and C. Hidalgo
LNF, Ciemat

== Details of contact person at LNF ==
I. Voldiner and E. de la Cal

== Description of the activity ==

A new gas injection system is under construction and will be installed in TJ-II for the next campaign. It will be used for GPI with a camera system
that allows 3 simultaneous filtered frames to apply the He I ratio technique. The objective is to get 2D measurements of the edge plasma
electron density ne and temperature Te with spatial resolution of 3 mm and temporal resolution down to 10 microseconds so as to study plasma turbulence.
The first step will be the commissioning of the puffing system in TJ-II plasmas and take first images to see that the mounting is correct and optimise the Helium puffing levels into the plasma.
The second step will be to obtain first images of ne and Te images and compare it with previous measurements and other diagnostics such as Reflectometry and Thomson Scattering [1].
The third step will be to find the best settings to study plasma turbulence [2].

[1] E. de la Cal E., Guasp J. and TJ-II Team 2011 Plasma Phys. Control. Fusion 53 085006

[2] E. de la Cal and TJ-II TEAM, Nucl. Fusion 56 (2016) 106031

== International or National funding project or entity ==
If applicable, enter funding here or write N/A

== Description of required resources ==
Required resources:
* Number of plasma discharges or days of operation: 4
* Essential diagnostic systems: Thomson Scattering, Reflectometry
* Type of plasmas (heating configuration): ECRH and NBI
* Specific requirements on wall conditioning if any: He puffing
* External users: need a local computer account for data access: yes/no
* Any external equipment to be integrated? Provide description and integration needs:

== Preferred dates and degree of flexibility ==
Preferred dates: (format dd-mm-yyyy)


== References ==
<references />

<hr>
[[TJ-II:Experimental proposals|Back to list of experimental proposals]]

[[Category:TJ-II internal documents]]
[[Category:TJ-II experimental proposals 2021]]

TJ-II:Experimental proposals

2018-03-05T13:27:28Z

E.delacal: /* Experimental proposals, 2018 Spring */

[[File:TJII_model.jpg|400px|thumb|right|TJ-II Model]]

== Creation of a new proposal ==

# Log in to the FusionWiki. If you don't have an account, request one by clicking 'Create account' in the left-hand menu.
# ''Type the name of your proposal page in the field below''. The required format is: 'TJ-II:Title of my proposal'. Note the 'TJ-II:' at the beginning!
# Click 'Create new proposal'. Your proposal page will be created. Edit and save (please use 'Show preview' before saving the final version).

<inputbox>
type=create
default=TJ-II:Title of my proposal
buttonlabel=Create new proposal with this title
preload=TJ-II:Proposal_template
</inputbox>

The proposal page is created on the basis of this [[TJ-II:Proposal template|Proposal template]]. You do not need to view or modify it.

== Inclusion of your proposal in the proposal list ==

* Edit the table below and add your proposal (instructions in the table).
* The link to your proposal is as follows: <nowiki>[[TJ-II:Title of your proposal|]]</nowiki> (the final character before the closing brackets <nowiki>]]</nowiki> is a vertical slash).

== Experimental proposals, 2018 Spring==
Deadline: March 7, 2018

{| class="wikitable sortable" width="100%" border="1" cellpadding="5" cellspacing="0" style="text-align:left"
|- style="background:#FFDEAD;"
! width="10%"| '''Nr.'''
! width="60%"| '''Title'''
! width="30%"| '''Proponent(s)'''




|-
 | 1
 | [[TJ-II:Observation of suprathermal ions with Neutral Particle Analyzers during electron cyclotron heating in the TJ-II stellarator|Observation of suprathermal ions with Neutral Particle Analyzers during electron cyclotron heating in the TJ-II stellarator]]
 | [mailto:josepmaria.fontdecaba@ciemat.es J.M. Fontdecaba]



|-
 | 2
 | [[TJ-II:Poloidal 2D scans to investigate potential and density profiles in the TJ-II stellarator using dual Heavy ion beam probe diagnostic|Poloidal 2D scans to investigate potential and density profiles in the TJ-II stellarator using dual Heavy ion beam probe diagnostic]]
 | [mailto:ridhimas757@gmail.com R. Sharma]

|-
 | 3
 | [[TJ-II:Validation of bootstrap predictions|Validation of bootstrap predictions]]
 | [mailto:joseluis.velasco@ciemat.es J.L.Velasco]

|-
 | 4
 | [[TJ-II:Transport analysis by means of the Transfer Entropy|Transport analysis by means of the Transfer Entropy]]
 | [mailto:boudewijn.vanmilligen@ciemat.es B.Ph. van Milligen]

|-
 | 5
 | [[TJ-II:Understanding an often observed transient rise in core electron temperature during pellet injection into TJ-II plasmas|Understanding an often observed transient rise in core electron temperature during pellet injection into TJ-II plasmas]]
 | [mailto:kieran.mccarthy@ciemat.es K J McCarthy]

|-
 | 6
 | [[TJ-II:Improving fuelling efficiency in TJ-II ECRH plasmas|Improving fuelling efficiency in TJ-II ECRH plasmas]]
 | [mailto:kieran.mccarthy@ciemat.es M Calvo]

|-
 | 7
 | [[TJ-II:The influence of a core fast electron population on pellet fuelling efficiency in TJ-II|The influence of a core fast electron population on pellet fuelling efficiency in TJ-II]]
 | [mailto:nerea.panadero@externos.ciemat.es N Panadero]

|-
 | 8
 | [[TJ-II:Studies of LIquid Metal insertion in TJ-II|Studies of LIquid Metal insertion in TJ-II]]
 | [mailto:tabares@ciemat.es P.Tabares]

|-
 | 9
 | [[TJ-II:Fast Camera studies with triple bundle|Fast Camera studies with triple bundle]]
 | [mailto:e.delacal@ciemat.es E. de la Cal]

|}

== Experimental proposals, 2017 Spring==
Deadline: January 26, 2017

{| class="wikitable sortable" width="100%" border="1" cellpadding="5" cellspacing="0" style="text-align:left"
|- style="background:#FFDEAD;"
! width="10%"| '''Nr.'''
! width="60%"| '''Title'''
! width="30%"| '''Proponent(s)'''




|-
 | 1
 | [[TJ-II:Search for physical mechanisms that lead to increase of turbulence following pellet injection|Search for physical mechanisms that lead to increase of turbulence following pellet injection]]
 | [mailto:kieran.mccarthy@ciemat.es Kieran McCarthy]


|-
 | 2
 | [[TJ-II:Effect of pellet injection on the radial electric field profile of stellarators|Effect of pellet injection on the radial electric field profile of stellarators]]
 | [mailto:silvagnidavide1@gmail.com,joseluis.velasco@ciemat.es Davide Silvagni, José L. Velasco]


|-
 | 3
 | [[TJ-II:Excitation of zonal flow oscillations by energetic particles|Excitation of zonal flow oscillations by energetic particles]]
 | [mailto:edi.sanchez@ciemat.es Edi Sánchez]


|-
 | 4
 | [[TJ-II:Radial electric field of low-magnetic-field low-collisionality NBI plasmas|Radial electric field of low-magnetic-field low-collisionality NBI plasmas]]
 | [mailto:joseluis.velasco@ciemat.es José L. Velasco]


|-
 | 5
 | [[TJ-II:Comparison of transport of on-axis and off-axis ECH-heated plasmas|Comparison of transport of on-axis and off-axis ECH-heated plasmas]]
 | [mailto:joseluis.velasco@ciemat.es,edi.sanchez@ciemat.es José L. Velasco, Edi Sánchez]
|-

 | 6
 | [[TJ-II:Impurity injection by laser blow-off: influence of main ions charge/mass on impurity confinement and transport|Impurity injection by laser blow-off: influence of main ions charge/mass on impurity confinement and transport]]
 | [mailto:belen.lopez@ciemat.es Belén López-Miranda]

|-

 | 7
 | [[TJ-II:PelletFuelling|PelletFuelling]]
 | [mailto:kieran.mccarthy@ciemat.es Kieran McCarthy]

|-

 | 8
 | [[TJ-II:Impurity density and potential asymmetries|Impurity density and potential asymmetries]]
 | [mailto:jose.regana@ciemat.es José M. García Regaña]

|-

 | 9
 | [[TJ-II:Investigation of turbulence spreading and information transfer in the TJ-II stellarator|Investigation of turbulence spreading and information transfer in the TJ-II stellarator]]
 | [mailto:boudewijn.vanmilligen@ciemat.es Boudewijn van Milligen]

|-

 | 10
 | [[TJ-II:Role of isotope effect on biasing induced transitions in the TJ-II stellarator|Role of isotope effect on biasing induced transitions in the TJ-II stellarator]]
 | [mailto:carlos.hidalgo@ciemat.es S. Ohshima]

|-

 | 11
 | [[TJ-II:Investigation of the mechanism of decoupling between energy and particle transport channels: Proposal for joint experiments in TJ-II and H-J|Investigation of the mechanism of decoupling between energy and particle transport channels: Proposal for joint experiments in TJ-II and H-J]]
 | [mailto:bing.liu@externos.ciemat.es,ulises.losada@ciemat.es Bing Liu, Ulises Losada]

|-

 | 12
 | [[TJ-II: Alfven Eigenmodes and biasing in TJ-II| Alfven Eigenmodes and biasing in TJ-II]]
 | [mailto:melnikov_07@yahoo.com A. Melnikov]

|-

 | 13
 | [[TJ-II: Potential asymmetries at low magnetic field | Potential asymmetries at low magnetic field ]]
 | [mailto:jose.regana@ciemat.es José M. García-Regaña]
|-

 | 14
 | [[TJ-II:NBI contribution to plasma fuelling|NBI contribution to plasma fuelling]]
 | [mailto:macarena.liniers@ciemat.es Macarena Liniers]

|-

 | 15
 | [[TJ-II: Investigation of plasma asymmetries in the TJ-II stellarator and comparison with Gyrokinetic simulations|Investigation of plasma asymmetries in the TJ-II stellarator and comparison with Gyrokinetic simulations]]
 | [mailto:Edi.sanchez@ciemat.es Edi Sanchez]

|-

 | 16
 | [[TJ-II:Effect of ECRH on the characteristics of Alfven Eigenmodes activity|Effect of ECRH on the characteristics of Alfven Eigenmodes activity]]
 | [mailto:alvaro.cappa@ciemat.es,enrique.ascasibar@ciemat.es,francisco.castejon@ciemat.es Álvaro Cappa, Enrique Ascasíbar, Paco Castejón]

|-

 | 17
 | [[TJ-II:Investigating the Alfvén Wave damping|Investigating the Alfvén Wave damping]]
 | [mailto:francisco.castejon@ciemat.es Paco Castejón, Álvaro Cappa, Enrique Ascasíbar]

|-

 | 18
 | [[TJ-II:L-H Transition and Isotope Effect in low magnetic ripple configurations|L-H Transition and Isotope Effect in low magnetic ripple configurations]]
 | [mailto:teresa.estrada@ciemat.es,Ulises.LosadaRodriguez@ciemat.es,Carlos.Hidalgo@ciemat.es Teresa Estrada,Ulises Losada,Carlos Hidalgo]

|-

 | 19
 | [[TJ-II:Measurements of radial correlation length and tilting of turbulent eddies by Radial Correlation Doppler Reflectometry|Measurements of radial correlation length and tilting of turbulent eddies by Radial Correlation Doppler Reflectometry]]
 | [mailto:teresa.estrada@ciemat.es,javier.pinzon@ipp.mpg.de,tim.happel@ipp.mpg.de Javier Pinzon, Tim Happel,Teresa Estrada]

|-

 | 20
 | [[TJ-II:Measurement of Te and ne of Blobs analyzing recycling helium emission in front of a poloidal limiter|Measurement of Te and ne of Blobs analyzing recycling helium emission in front of a poloidal limiter]]
 | [mailto:e.delacal@ciemat.es, Eduardo de la Cal]

|-
|}

== See also ==

* [[TJ-II:Experimental program]] (current)
* [http://intranet-fusion.ciemat.es/document-server/tj-ii-experimental-program/ Experimental programs for earlier years (2002-2016)] (Intranet, password required)

[[Category:TJ-II internal documents]]
[[Category:TJ-II experimental proposals]]

TJ-II:Fast Camera studies with triple bundle

2018-03-05T13:19:19Z

E.delacal: Triple Bundle measurements in TJ-II

== Experimental campaign ==
2018 Spring

== Proposal title ==
'''' Fast Camera studies with triple bundle""

== Name and affiliation of proponent ==
E. de la Cal, N. Villoslada, B. van Milligen and C. Hidalgo, Laboratorio Nacional de Fusión, CIEMAT, Spain

== Details of contact person at LNF (if applicable) ==
E. de la Cal

== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)==
A triple bundle recently acquired will be used to simultaneously measure three atomic line intensities in Helium plasmas. The goal is to obtain simultaneously the plasma edge electron temperature and density and compare them with other diagnostics as done in the past with a double bundle <ref>E. de la Cal , J. Guasp and TJ-II Team 2011 Plasma Phys. Control. Fusion 53 085006</ref> .
Further, the camera exposure time will be reduced to the minimum acceptable value taking into account the Signal to Noise Ratio in order to see if turbulence-relevant times can be achieved (of the order of a few tens of microseconds). If this is possible, the electron density and temperature of Blobs will be measured and see if the plasma turbulence is coupled to the neutral density as proposed in the past <ref>E. de la Cal and The TJ-II Team 2016 Nucl. Fusion 56 106031</ref>.

== If applicable, International or National funding project or entity ==
ENE2015-68206-P
== Description of required resources ==
Required resources:
* Number of plasma discharges or days of operation: 1
* Essential diagnostic systems: Thomson Scattering, microwave interferometer,
* Type of plasmas (heating configuration): Helium Plasmas with Limiter C inside the LCFS, ECRH and NBI, Standard Configuration
* Specific requirements on wall conditioning if any:
* External users: need a local computer account for data access: yes/no
* Any external equipment to be integrated? Provide description and integration needs:

== Preferred dates and degree of flexibility ==
Preferred dates: June 2018

== References ==
<references /> 

<hr>
[[TJ-II:Experimental proposals|Back to list of experimental proposals]]

[[Category:TJ-II internal documents]]
[[Category:TJ-II experimental proposals]]

TJ-II:Fast camera

2015-05-07T10:11:52Z

E.delacal:

[[TJ-II]] disposes of various fast camera systems for plasma imaging, a detailed description can be found elsewhere.
<ref name="delaCal">[http://onlinelibrary.wiley.com/doi/10.1002/ctpp.201000039/pdf E. de la Cal et al, ''The visible intensified cameras for plasma imaging in the TJ-II stellarator'', Contrib. Plasma Phys. (2010)]</ref>.

Different topics have been studied such as '''Turbulence'''
<ref name="Alonso">[http://dx.doi.org/10.1088/0741-3335/48/12B/S44 J.A. Alonso et al, ''Impact of different confinement regimes on the two-dimensional structure of edge turbulence'', Plasma Phys. Control. Fusion '''48''' (2006) B465-B473]</ref>
<ref name="Carralero">[http://dx.doi.org/10.1016/j.jnucmat.2009.01.140 D. Carralero et al, ''Turbulence studies by fast camera imaging experiments in the TJII stellarator'', Journal of Nuclear Materials '''390-391''' (2009) 457-460]</ref>
<ref name="delaCal2">[http://iopscience.iop.org/0741-3335/56/10/105003/ E. de la Cal et al, ''Double imaging with an intensified visible fast camera to visualize the fine structure of turbulent coherent plasma structures (blobs) in TJ-II'', 2014 Plasma Phys. Control. Fusion 56 105003)]</ref>, '''Dust'''
<ref name="delaCal3">[http://iopscience.iop.org/0741-3335/55/6/065001/ E. de la Cal et al, ''Dust observation with a visible fast camera in the TJ-II stellarator'', 2013 Plasma Phys. Control. Fusion 55 065001 )]</ref>, or '''Spectroscopic 2-Dimensional Te and ne imaging''',
<ref name="delaCal4">[http://iopscience.iop.org/0741-3335/53/8/085006/ E. de la Cal et al, ''Two-dimensional imaging of edge plasma electron density and temperature by the passive helium emission ratio technique in TJ-II'', 2011 Plasma Phys. Control. Fusion 53, 085006]</ref>

The main system is located in [[TJ-II:Sectors|sector]] B8, [[TJ-II:Ports|port]] B8TANG, viewing the [[TJ-II:Limiter|poloidal limiter]] in sector C3 tangentially.

The TJ-II Visible Camera Team has installed in collaboration with NIFS (Japan) a Fast Camera in '''LHD Stellarator'''
<ref name="Shoji">[http://www.nifs.ac.jp/report/annrep10/pdf/021.pdf M. Shoji et al et al, ''Tangentially Viewing Fast Camera Measurements in Core Density Collapse in LHD Stellarator'', Annual Report of National Institute for Fusion Science 2010 ]</ref>.

In the framework of EUROFUSION program, the group has leaded the installation and operation of the KL8 Wide Angle Visible Fast Camera in '''JET Tokamak''' (UK).

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 ==

Three Photron Fast Cameras (APX-RS and SA1) are employed at TJ-II [http://www.photron.com/ Photron].
Sampling speed (measured in frames per second, fps) and image size can be selected depending on active area of the MOS sensor, but there is a trade-off:
5000 fps with 1024 x 1024 pixels(full frame) and up to 200000 fps (maximum ever employed so far) with 182 x 80 pixels
The dynamic range of the sensor is 8 bits, and the memory size is 8 GB.

[[File:camaras1.png]]
[[File:camaras2.png|500px|]]

== 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.
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]]

== Videos ==

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.

=== Double imaging to visualize the fine structure of Blobs at ultra-short exposure time of 100 ns<ref name="delaCal2"> </ref>===

[[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.
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 ne and Te showing ELM-like Edge Bursts<ref name="delaCal4"> </ref>===

[[File:25623wComm_Photo000001.jpg|700px|link=http://www-fusion.ciemat.es/fileshare/doc_exchange/camaras/HeliumRatio_ELMs.m4v]]

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 ne and Te.

=== Dust Visualisation <ref name="delaCal3"> </ref>===

[[File:Dust.png|700px|link=http://www-fusion.ciemat.es/fileshare/doc_exchange/camaras/delaCal_dust.mp4]]

Dust is observed in the TJ-II stellarator with a fast camera equipped with a bifurcated coherent fibre-bundle system that allows different set-ups such as dual filtering of atomic lines or a stereoscopic view to obtain tangential and perpendicular (to the magnetic field) observations simultaneously. The camera looks to a poloidal limiter that can be biased and it is observed that when a negative voltage is applied, dust from the limiter is ejected intensely once a certain threshold voltage is exceeded.

[[File:Polvo1b.jpg|300px|link=media:Polvo1b.gif|Dust movie]]

First insertion of the poloidal limiter after a lithiation of the vacuum vessel. Tangential observation, 15 kHz sampling rate. The ejection of lithium flakes from the carbon surface can be seen clearly at the beginning of the discharge. At the end of the video, as the plasma becomes colder, the flakes penetrate deeper into it until they float freely in the collapsing discharge.

=== The Visible Intensified Fast Camera with Wide-angle view of JET ILW experiment <ref name="delaCal5"> </ref>===

[[File:Jet.png|500px|link=http://www-fusion.ciemat.es/camaras/JETselection.mp4]]

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 />

2015-04-22T09:39:15Z

E.delacal:

TJ-II:Fast camera

2015-04-22T09:25:48Z

E.delacal:

[[TJ-II]] disposes of various fast camera systems for plasma imaging, a detailed description can be found elsewhere.
<ref name="delaCal">[http://onlinelibrary.wiley.com/doi/10.1002/ctpp.201000039/pdf E. de la Cal et al, ''The visible intensified cameras for plasma imaging in the TJ-II stellarator'', Contrib. Plasma Phys. (2010)]</ref>.

Different topics have been studied such as '''Turbulence'''
<ref name="Alonso">[http://dx.doi.org/10.1088/0741-3335/48/12B/S44 J.A. Alonso et al, ''Impact of different confinement regimes on the two-dimensional structure of edge turbulence'', Plasma Phys. Control. Fusion '''48''' (2006) B465-B473]</ref>
<ref name="Carralero">[http://dx.doi.org/10.1016/j.jnucmat.2009.01.140 D. Carralero et al, ''Turbulence studies by fast camera imaging experiments in the TJII stellarator'', Journal of Nuclear Materials '''390-391''' (2009) 457-460]</ref>
<ref name="delaCal2">[http://iopscience.iop.org/0741-3335/56/10/105003/ E. de la Cal et al, ''Double imaging with an intensified visible fast camera to visualize the fine structure of turbulent coherent plasma structures (blobs) in TJ-II'', 2014 Plasma Phys. Control. Fusion 56 105003)]</ref>, '''Dust'''
<ref name="delaCal3">[http://iopscience.iop.org/0741-3335/55/6/065001/ E. de la Cal et al, ''Dust observation with a visible fast camera in the TJ-II stellarator'', 2013 Plasma Phys. Control. Fusion 55 065001 )]</ref>, or '''Spectroscopic 2-Dimensional Te and ne imaging''',
<ref name="delaCal4">[http://iopscience.iop.org/0741-3335/53/8/085006/ E. de la Cal et al, ''Two-dimensional imaging of edge plasma electron density and temperature by the passive helium emission ratio technique in TJ-II'', 2011 Plasma Phys. Control. Fusion 53, 085006]</ref>

The main system is located in [[TJ-II:Sectors|sector]] B8, [[TJ-II:Ports|port]] B8TANG, viewing the [[TJ-II:Limiter|poloidal limiter]] in sector C3 tangentially.

The TJ-II Visible Camera Team has installed in collaboration with NIFS (Japan) a Fast Camera in '''LHD Stellarator'''
<ref name="Shoji">[http://www.nifs.ac.jp/report/annrep10/pdf/021.pdf M. Shoji et al et al, ''Tangentially Viewing Fast Camera Measurements in Core Density Collapse in LHD Stellarator'', Annual Report of National Institute for Fusion Science 2010 ]</ref>.

In the framework of EUROFUSION program, the group has leaded the installation and operation of the KL8 Wide Angle Visible Fast Camera in '''JET Tokamak''' (UK).

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 ==

Three Photron Fast Cameras (APX-RS and SA1) are employed at TJ-II [http://www.photron.com/ Photron].
Sampling speed (measured in frames per second, fps) and image size can be selected depending on active area of the MOS sensor, but there is a trade-off:
5000 fps with 1024 x 1024 pixels(full frame) and up to 200000 fps (maximum ever employed so far) with 182 x 80 pixels
The dynamic range of the sensor is 8 bits, and the memory size is 8 GB.

[[File:camaras1.png]]
[[File:camaras2.png]]

== 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.
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]]

== Videos ==

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===

[[File:Double_Imaging.jpg|300px|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.
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===

[[File:25623wComm_Photo000001.jpg|300px|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: 60μs. V: 750 V.
ECH and NBI plasma with <ne>. 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 <ne> and <Te> can be obtained [4].

=== Limiter Recycling ===

[[File:24119.jpg|300px|link=media:24119.gif|Limiter recycling movie]]

Without filter and 75 mm lens. Speed: 54000 fps. Exposure time: 9μs. V: 650 V.
ECH plasma with <ne> = 5x1018 m-3. Recycling at limiter positioned on the LCFS. The bright spot is Blackbody radiation from a glowing Langmuir probe on the limiter corner.

=== Helium Puffing ===

[[File:24080.jpg|300px|link=media:24080.gif|Helium puffing movie]]

Without filter and 75 mm lens. Speed: 100000 fps. Exposure time: 1μs. V: 700 V.
ECH plasma with <ne> = 5x1018 m-3. Helium puffing through the limiter 35 mm outside LCFS.

=== Lithium emission (Li I filter) ===

[[File:18152.jpg|300px|link=media:18152.gif|Surface interaction movie]]

TJ-II plasma observed from a tangential port at 17.5 kHz sampling rate, with a lithium filter and image intensifier. In the field of view, the two most prominent areas of plasma-wall interaction can be seen: the poloidal limiter (lower) and the hardcore (helical limiter). As the plasma transits form ECH to NBI plasmas, the interaction level diminishes and becomes predominantly centered in the limiter. <ref name="Carralero"></ref> From the lithium emission fluctuations information on the electron density fluctuations can be gained. <ref name="delaCal"></ref>

=== Dust Visualisation <ref name="delaCal3"></ref>===
Dust is observed in the TJ-II stellarator with a fast camera equipped with a bifurcated coherent fibre-bundle system that allows different set-ups such as dual filtering of atomic lines or a stereoscopic view to obtain tangential and perpendicular (to the magnetic field) observations simultaneously. The camera looks to a poloidal limiter that can be biased and it is observed that when a negative voltage is applied, dust from the limiter is ejected intensely once a certain threshold voltage is exceeded.

[[File:Polvo1b.jpg|300px|link=media:Polvo1b.gif|Dust movie]]

First insertion of the poloidal limiter after a lithiation of the vacuum vessel. Tangential observation, 15 kHz sampling rate. The ejection of lithium flakes from the carbon surface can be seen clearly at the beginning of the discharge. At the end of the video, as the plasma becomes colder, the flakes penetrate deeper into it until they float freely in the post-discharge plasmoid.

== References ==
<references />

2014-04-10T08:51:50Z

E.delacal:

2011-05-17T09:22:59Z

E.delacal: /* Double Imaging of two He I lines */

[[TJ-II]] disposes of various fast camera systems for plasma imaging
<ref name="Alonso">[http://dx.doi.org/10.1088/0741-3335/48/12B/S44 J.A. Alonso et al, ''Impact of different confinement regimes on the two-dimensional structure of edge turbulence'', Plasma Phys. Control. Fusion '''48''' (2006) B465-B473]</ref>
<ref name="Carralero">[http://dx.doi.org/10.1016/j.jnucmat.2009.01.140 D. Carralero et al, ''Turbulence studies by fast camera imaging experiments in the TJII stellarator'', Journal of Nuclear Materials '''390-391''' (2009) 457-460]</ref>
<ref name="delaCal">[http://onlinelibrary.wiley.com/doi/10.1002/ctpp.201000039/pdf E. de la Cal et al, ''The visible intensified cameras for plasma imaging in the TJ-II stellarator'', Contrib. Plasma Phys. (2010)]</ref>.
The main system is located in [[TJ-II:Sectors|sector]] B8, [[TJ-II:Ports|port]] B8TANG, viewing the [[TJ-II:Limiter|poloidal limiter]] in sector C3 tangentially.

== Cameras ==

The newest fast camera employed at TJ-II is a [http://www.photron.com/ Photron] SA1 camera.
Sampling speed (measured in frames per second, fps) and image size can be selected, but there is a trade-off:
* 5000 fps with 1024 x 1024 pixels(full frame)
* 10000 fps with 512 x 512 pixels
* 200000 fps (maximum ever employed so far) with 182 x 80 pixels

The dynamic range of the sensor is 8 bits, and the memory size is 8 GB.

== Image Intensifier for Fast Camera==

A [http://sales.hamamatsu.com/en/home.php Hamamatsu] C9548-03BL series image intensifier is used.
This is a 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 and somewhat slower phosphor screen (P-24). Both stages are optically coupled by a Fiber Optic Plate (FOP) which transfers the output signal from the first to the second.

[[File:TJ-II_Fast_camera_diagram.jpg|800px|thumb|center|Schematic diagram of the TJ-II fast camera installation]]

== Videos ==

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 of two He I lines ===

[[File:25623wComm_Photo000001.jpg|300px|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: 60μs. V: 750 V.
ECH and NBI plasma with <ne>. 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 <ne> and <Te> can be obtained [4].

=== Limiter Recycling ===

[[File:24119.jpg|300px|link=media:24119.gif|Limiter recycling movie]]

Without filter and 75 mm lens. Speed: 54000 fps. Exposure time: 9μs. V: 650 V.
ECH plasma with <ne> = 5x1018 m-3. Recycling at limiter positioned on the LCFS. The bright spot is Blackbody radiation from a glowing Langmuir probe on the limiter corner.

=== Helium Puffing ===

[[File:24080.jpg|300px|link=media:24080.gif|Helium puffing movie]]

Without filter and 75 mm lens. Speed: 100000 fps. Exposure time: 1μs. V: 700 V.
ECH plasma with <ne> = 5x1018 m-3. Helium puffing through the limiter 35 mm outside LCFS.

=== Surface Interaction ===

[[File:18152.jpg|300px|link=media:18152.gif|Surface interaction movie]]

TJ-II plasma observed from a tangential port at 17.5 kHz sampling rate, with a lithium filter and image intensifier. In the field of view, the two most prominent areas of plasma-wall interaction can be seen: the poloidal limiter (lower) and the hardcore (helical limiter). As the plasma transits form ECH to NBI plasmas, the interaction level diminishes and becomes predominantly centered in the limiter. <ref name="Carralero"></ref> From the lithium emission fluctuations information on the electron density fluctuations can be gained. <ref name="delaCal"></ref>

=== Dust ===

[[File:Polvo1b.jpg|300px|link=media:Polvo1b.gif|Dust movie]]

First insertion of the poloidal limiter after a lithiation of the vacuum vessel. Tangential observation, 15 kHz sampling rate. The ejection of lithium flakes from the carbon surface can be seen clearly at the beginning of the discharge. At the end of the video, as the plasma becomes colder, the flakes penetrate deeper into it until they float freely in the post-discharge plasmoid.

== References ==
<references />

File:25623wComm Photo000001.jpg

2011-05-17T09:21:50Z

E.delacal: