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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. For more details on the math see Klystron Math 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 `l_B`. For small signal ratio, `V_b/V_a`, it can be shown that an expression for `l_B` is
`l_B=2(u_0/omega)(V_a/V_b)`
where `u_0` is the speed of the electrons leaving the Anode, `omega` is the radian frequency of the buncher voltage, `V_b`, and `V_a` is the anode voltage that produces speed `u_0`. The position, `x_(Ca)`, of the catcher is`x_(Ca)=x_B+l_B`
where `x_B` 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 selection of the spatial profile of the buncher voltage.