Microprocessor-based digitizers combined with preamplifiers and detectors as a solution for EMI suppression

A strong 8–9MHz noise from the RF plasma heating generators forms additional difficulties in the diagnostic signal measurements in the U-3M and U-2M torsatrons compared with other stellarators and tokamaks. Set of new optical diagnostics (20-channels SXR and bolometers, 12- channels Hα) with a temporal resolution of up to 4 microseconds has been designed and is successfully used in the noisy RF plasma conditions of U-3M and U-2M torsatrons as well as in the QSPA Kh-50 plasma accelerator. In the original electronics design all the diagnostics components, including the STM-32-microporcessor-based data acquisition system, are assembled in a single unit (without analog signals or digital interface wires). This design allows one to prevent the ground loop interference, to remove the RF load on diagnostics components and to increase substantially the system protection from different electromagnetic noises.