Criteria for an optimum laser detector system for Thomson scattering experiments on fusion plasmas

Different laser systems (Excimer, ruby, neodymium-glass, neodymium-Yag, and CO2 laser) and their accompanying detection system were compared in order to derive optimization criteria. Three boundary cases (number of scattered photons, plasma radiation or detector noise dominates) in which detector, background, or signal noise dominated the detection of scattered light, were treated. For the transition domains, a detailed study of each case is required. For the three boundary cases, optimization criteria are derived on the basis of analytical results. If scattered photons (signal noise) dominates the signal to noise ratio, systems with large wavelength are preferable, as well as if plasma radiation dominates. If detector noise dominates, a lower noise detection system is preferable.