Microwave Absorber

As a particle beam of protons moves through a beam pipe, a negative image charge develops and travels along with particle beam in the wall of the beam pipe. As long as the beam pipe is smooth, this doesn’t cause much of a problem, but when there are bellows or aperture changes, these points cause high frequency resonances that interfere with other electronic devices, such as instrumentation. The ferrite rods absorb these high frequencies.