MULTI-PULSE THOMSON SCATTERING SYSTEM FOR TEXTOR

H. J. VAN DER MEIDEN 1, T. OYEVAAR 1, S.K. VARSHNEY 1, E. UZGEL 3,
 M.YU. KANTOR 2,D.V. KOUPRIENKO 2, A. POSPIESZCZYK 3,
C.J. BARTH 1, A.J.H. DONNE 1 and the TEXTOR TEAM 3

1 FOM-Institute for Plasma Physics Rijnhuizen*, Association EURATOM-FOM, 
P.O.Box 1207, 3430 BE Nieuwegein, The Netherlands. www.rijnh.nl 
2 Ioffe Institute, RAS, Saint Petersburg, 194021, Russia.
3 Institut für Plasmaphysik*, FZ Jülich GmbH/Euratom Association, 
D-52425 Jülich, Germany.
* partners in the Trilateral Euregio Cluster

In December 2003 a 10 kHz multi-position Thomson scattering diagnostic with 
high spatial resolution became operational on the TEXTOR tokamak. In the 
initial phase of operation, one burst of 18 pulses of 12 J each with a 
repetition rate of 5 kHz could be extracted from the laser system. The 
installation of a low dope ruby rod (spring 2005) resulted in a system, which 
can deliver higher pulse energy, and moreover a divergence of better than 
0.7 mrad, leading to a big improvement in the detection of TS photons. 
The achieved laser energy of more than 15 J per pulse enables to measure 
electron temperature and density profiles with an observational error of 8% on 
the electron temperature (Te) and 4% on the electron density (ne) at ne = 2.5 x 10^19 m-3, per spatial element of 7.5 mm. The viewing optics enables to sample 
either the full plasma diameter of 900 mm with 120 spatial channels of 7.5 mm 
each, or a 160 mm long edge chord with 98 spatial channels of 1.7 mm each. 
This presentation involves the description of the TS system, as well as an 
overview of the technical research history, which led to the realisation of 
this system. It will be shown, that the competition between Thomson scattering 
signal and plasma light signal is such, that the measurement accuracy of Te 
and ne complies with the above mentioned specifications.