ITER LIDAR performance analysis

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<Te<40 keV and ne >3×10^19 m−3 at an accuracy of < 10% for Te. 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 λ=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 Te >5 keV with a combination of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (λ0=1064 nm, Δλ <1 nm, 5 J, and Δt =250 ps FWHM , 5–10 Hz) and S20, GaAs, and GaAsP microchannel plate photomultipliers (Δt =300 ps FWHM, effective quantum efficiency, EQE=3%–4%, and D=18 mm). In order to reach the required Te of 500 eV with Nd:YAG first harmonic, this choice requires a development of fast near infrared detectors.