Effect of Energetic-Ion/Bulk-Plasma- driven MHD Instabilities on Energetic Ion Loss in the Large Helical Device Kunihiro OGAWA, Mitsutaka ISOBE, Kazuo TOI, Masaki OSAKABE, Kunihiro OGAWA, Mitsutaka ISOBE, Kazuo TOI, Masaki OSAKABE, Fumitake WATANABE, Akihiro SHIMIZU, Fumitake WATANABE, Akihiro SHIMIZU, D D onald onald A. Spong A. Spong 3 , , Dougla Dougla ss S Darrow ss S Darrow 4 , Satoshi OHDACHI, Satoru SAKAKIBARA, LHD Group. , Satoshi OHDACHI, Satoru SAKAKIBARA, LHD Group. National Institute for Fusion Science, Nagoya Univ. National Institute for Fusion Science, Nagoya Univ. 1 , Kyoto , Kyoto Univ. Univ. 2 , ORNL , ORNL 3 , PPPL , PPPL 4 At ASIPP 06/23/22
At ASIPP 2014/10/20. Effect of Energetic-Ion/Bulk-Plasma-driven MHD Instabilities on Energetic Ion Loss in the Large Helical Device. - PowerPoint PPT Presentation
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Effect of Energetic-Ion/Bulk-Plasma-driven MHD Instabilities on Energetic Ion Loss in the Large Helical Device
National Institute for Fusion Science, Nagoya Univ.National Institute for Fusion Science, Nagoya Univ.11, Kyoto Univ., Kyoto Univ.22, ORNL, ORNL33, PPPL, PPPL44
At ASIPP04/20/23
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Contents of my presentationBackground and purpose
– The meaning of study
Experimental setups
– scintillator-based lost ion probe
Experimental result
– Increase of lost ion flux due to TAE
Calculation setups
– DELTA5D code (guiding-centre orbit code)
The result of calculation
– Compare with experimental result
Summary
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BackgroundAnomalous loss of fast ion in
fusion device
– It might cause localized damage of first wall
Understanding of loss process of fast ion is needed
– Alfvén eigenmode (AE)-induced loss is observed on many tokamaks
– Low frequency MHD modes such as NTM also cause fast-ion losses
Contribution from the 3D plasma is needed to confirm the theory
[1] D.DARROW et al., NF (1997)
GAE induced loss in TFTR [1]
m/n=2/1 NTM induced loss in AUG [2]
Fast Ion Loss NTM mode
[2] M. Garíca-Muñoz et.al, NF (2007)
Experimental setups
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The structure of Helical system
plasma shape and magnetic field
– Tokamak : poloidal cross sections at any toroidal angle are the same
• Magnetic surface is created w/ plasma current.
– Helical : poloidal cross section have certain cycle
• Magnetic surface exist w/o plasma current.
Safety factor
– Increase toward the outside (normally, q = ~1 to ~3)
– decrease toward the outside (normally, q = ~3 to ~ 0.6)
Flux surface of EAST
Flux surface of LHD
Profile of safety factor
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Scintillator-Based Lost-Fast Ion Probe (SLIP)
Double aperture structure allows fast ions having certain velocities to enter
Scintillation points has information of velocity and pitch angle () of fast ions
This SLIP has two sets of double apertures :“Bi-directional lost-fast ion probe”
– It can be applicable to both cases of CW or CCW direction of Bt
Observation of co-going lost fast ions at relatively low field (Bt < 0.75 T)