Electron Buncher for Klystron This animation shows how the electron beam in a klystron amplifier is formed, accelerated by the anode, and then modulated and bunched by the buncher electrodes. The emphasis here is on the bunching process. The basic concept of the klystron is to use the electron energy increase provided at the anode to modulate the potential between the electrodes of the catcher and thereby increase the power of the signal that was originally applied to the buncher. The most important step in this process is to have the buncher electrodes bunch the electrons so that there is a large electron density when they pass through the catcher. This animation give the learner some insight into parameters that are important to this bunching process. During the first half of the buncher temporal cycle the electrons are slowed down and these are colored blue. During the second half of the buncher cycle the speed of the electrons is increased and these electrons are colored red. The goal is to have a large number of red atoms catch up to a large number of blue atoms after a distance from the buncher called lB. For small signal, Vb/Va, it can be shown that an expression for lB is lB=2*(u0/w)*(Va/Vb) where u0 is the speed of the electrons leaving the Anode, w is the radian frequency of the buncher voltage, Vb, and Va is the anode voltage that produces speed u0. The position, xCa, of the catcher is xCa=xB+lB where xB is the position of the buncher along the x axis. Radio buttons are available for selction of the time profile of the input wave. Radio buttons are also avialable for selction of the spatial profile of the buncher voltage. The parameters available are the following: 1. DC voltage level applied to the anode 2. AC voltage amplitude which is applied to the buncher electrodes 3. Length of electrode elements 4. Spacing between electrode element pairs 5. Frequency of AC voltage applied to buncher electrodes
Click here for Klystron Math

V0 dV lenB dxB freq Single Step Square Wave Temporal Input Sine Wave Temporal Input SawTooth Wave Temporal Input Computed Spatial E Field Flat Spatial E Field