Studies on fast ion distribution

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Studies on fast ion distribution

• Correlated with
• the spectroscopy diagnostics measurements
• Gerarda Apruzzese
• http//www.afs.enea.it/apruzzes/
• CRE Frascati - ENEA
• Culham, July the 24th

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Aim of this work

• Analysis of the positive and negative aspects of
  the diagnostics using the CX spectrum
• and
• their possible development at JET

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Diagnostics compared in the analysis

• the diagnostic FIDA
• developed in DIII-D
• W.W.Heidbrink et al., PPCF 49, (2007)
  1457-1475
• the fast ion CXRS diagnostic
• developed in Textor
• Proceedings of the 17th Topical Conference
  on High-Temperature Plasma Diagnostics,
  Albuquerque, New Mexico, May 2008

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FIDA Diagnostic( Fast Ion Da Analysis)

• Measurement of the vertical component of
  perpendicular energy
• CX emission spectrum of re-neutrals generated by
  beam
• CX ( beam - plasma ions) fast ions
• CX ( fast ions beam )
  re-neutrals

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FIDA measurements in DIII-D
Successful on DIII-D in detecting both NB and
ICRH accelerated D
Y.Luo and W.W. Heidbrink, RSI 78, 033505 (2007)
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For FIDA success it is necessary

• Vertical views ( Doppler shift only due to
  gyromotion of fast ions)
• Good hardware ( f of spectrometer, detector,
  system for avoiding detector saturation)
• Beam modulation ( for subtracting the background)

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Complications of FIDA

• The extracted signal is 10 times less the
  detected signal so
• GOOD HARDWARE and APPROPRIATE OPTICAL VIEW
  are required
• Spectral overlap with BES spectrum
• Intense cold Dalpha light
• Halo (from CX plasma-beam)

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The fast ion CXRS diagnostic

• Using the Fokker-Plank code to simulate the Da
  beam emission spectrum
• Good results on Textor, where a favourable
  viewing geometry permits to separate the
  contributions due to the fast ions and the beam
  emission spectrum (BES)

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CX measurements at TEXTOR
spectrum
simulation
Blu wing (slowing down)
Red wing (BES)
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Situation at JET

• First and preliminary analysis done by von
  Hellermann and Delabie using the technique of
  fast ion CX diagnostic. Good results.
• http//users.jet.efda.org/pages/d-task-force/
  meetings/2008/080626/Delabie.ppt
• FIDA diagnostic requires a vertical viewing line
• avoiding the divertor region (characterised by
  strong emission) and dedicated equipment.

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Next step

• for FIDA firstly, check of vertical view
• for fast ion CX
• Prepare future upgrading of spectrometer (Textor
  group)
• Extend the simulation modelling in order to
  include effects of instabilities on slowing down
  distribution function (Frascati and Textor
  groups)