Reflectometry systems for the DIII-D tokamak

A seven‐channel reflectometer system has been installed on the DIII‐D tokamak. This diagnostic will be used to investigate electron density profiles and fluctuations during both L‐ and H‐mode operation. The reflectometer is configured as a narrow‐band FM radar system utilizing analog electronics and compound modulation. These techniques have been tested in the laboratory yielding a spatial accuracy of ±1 cm and temporal resolution of ∼1 ms.