Analysis of the Feedback-Loop Stability in the RF System of the U-70 Synchrotron

We present a systematic approach for investigating the stability of the accelerating system used in the U-70 proton synchrotron (Institute for High-Energy Physics). This system employs tunable ferrite-loaded cavities and is encircled by six feedback loops (both dedicated and spurious) with a cross-talk through a heavy beam loading, high accelerating rate, and the overlapping of the loop passbands. Ensuring the safety margin against self-excitation of the RF system imposes constraints on the limiting intensity of the beam that is accelerated in the synchrotron