In this paper, we propose a collective Thomson scattering (CTS) diagnostic for fast ion measurements for the GDT (gas-dynamic trap) facility at the Budker Institute. The diagnostic utilizes the 54.5 GHz gyrotron usually used for electron cyclotron resonance heating as a source of probe radiation and is aimed at reconstruction of distributions over transverse and longitudinal velocities of NBI-driven ions in the plasma core. Here we present a feasibility study of this concept showing a possibility to receive a strong CTS signal of several hundred eVs for a wide range of GDT parameters. The main limitations come from the refraction of the probe and scattered radiation propagating in inhomogeneous plasma: to provide well-resolved CTS measurements the on-axis plasma density should be kept less than 1.5 · 1013 cm−3 while usual GDT discharges correspond to the density of (0.9 − 1.3)· 1013 cm−3.
Requirements for fast particle measurements on ITER and candidate measurement techniques