Preliminary results of the new fast ion CTS systems at TEXTOR and ASDEX Upgrade*

Upgraded and new fast ion collective Thomson Scattering (CTS) diagnostics using high power gyrotrons have been implemented on TEXTOR and ASDEX Upgrade tokamaks, respectively. Commissioning of the systems is currently underway and first results have been obtained from TEXTOR. The slowing down of fast ions due to the switching off of the NBI will be discussed, and the measured time evolution will be compared to numerical simulations. The commissioning activities on ASDEX Upgrade of the 105 GHz receiver and the new 1 MW, 10 s gyrotron will be described. Fast ion physics will be a key research goal on ITER, where confined alpha particles will play a dominant role. CTS using gyrotrons has the potential to satisfy this prime ITER diagnostic need for measuring the spatially localized velocity distributions of confined fast ions.