Beurskens M N A, Giudicotti L, Kempenaars M, Scannell R, Walsh M J
EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
Rev Sci Instrum. 2008 Oct;79(10):10E727. doi: 10.1063/1.2969097.
The core LIDAR Thomson scattering for ITER is specified for core profile measurements with a spatial resolution of 7 cm (a/30) for the range of 500 eV<T(e)<40 keV and n(e)>3x10(19) m(-3) at an accuracy of <10% for T(e). These specifications are verified using a full profile Monte Carlo simulation code. In the simulations it is assumed that the input transmission is 50% and the collection transmission is 10% for lambda=300-1200 nm and F/#=6-17. A crucial design decision lies on the choice of laser and detector combination. It is evaluated that the system can meet its spatial and accuracy specifications for higher temperatures of T(e)>5 keV with a combination of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (lambda(0)=1064 nm, Delta lambda<1 nm, 5 J, and Delta t(FWHM)=250 ps, 5-10 Hz) and S20, GaAs, and GaAsP microchannel plate photomultipliers (Delta t(FWHM)<300 ps, effective quantum efficiency, EQE=3%-4%, and D=18 mm). In order to reach the required T(e) of 500 eV with Nd:YAG first harmonic, this choice requires a development of fast near infrared detectors.
