Advances in the CO2 laser collective Thomson scattering fast ion/alpha particle diagnostic (abstract)

A collective Thomson scattering diagnostic is being developed for the measurement of confined fast ions in hot, dense plasmas. This includes such measurements as the ion tail in JT-60U and the alphas produced in a burning reactor or the upgraded Joint European Torus device. The diagnostic also has the capability of measuring the isotopic ratio of the core ions such as the D/T ratio (required in optimizing a burning plasma experiment). The advances under development for this diagnostic include improvements in the high power source laser, increased bandwidth and reduced noise in the receiver, and the development of an intermediate frequency electronic filter bank. Such improvements are designed to permit the temporal measurement of the fast ions and improve the accuracy in determining their velocity distribution. Modeling of the expected scattered signals produced by these improvements and the diagnostics capability to measure the velocity distribution and isotopic ratio are presented.