Transcript Studies on fast ion distribution

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
Aim of this work
• Analysis of the positive and negative
aspects of the diagnostics using the CX
spectrum
and
• their possible development at JET
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 HighTemperature Plasma Diagnostics, Albuquerque, New
Mexico, May 2008
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
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)
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)
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)
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)
CX measurements at TEXTOR
spectrum
Blu wing
(slowing
down)
simulation
Red wing
(BES)
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.
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)