Studies on fast ion distribution

Correlated with

the spectroscopy diagnostics measurements

Gerarda Apruzzesehttp://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 High-

Temperature Plasma Diagnostics, Albuquerque, New Mexico, May 2008

FIDA Diagnostic( Fast Ion D 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 D 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

Red wing (BES)

Blu wing (slowing down)

spectrum simulation

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)