Part 3/10:
Injection of a Weak Signal: The first cavity resonator is excited by an external high-frequency signal, often introduced via a coaxial cable. This initial signal is weak but resonant with the cavity's frequency.
Modulation of Electron Velocities: The electric field inside the first resonator causes the electrons to accelerate and decelerate alternately, depending on their phase relative to the field. This modulation results in a change in electron velocities entering the drift space—a region devoid of fields.
Bunch Formation in Drift Space: As electrons travel through the drift space, faster electrons catch up with slower ones, forming tight bunches. These electron bunches are crucial because they contain a higher concentration of charge at specific intervals.