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How does the echo of a radio wave from Venus depend on the rotation speed and direction of the planet?

There is a Doppler signal. The frequency of the reflected wave is changed by the reflector moving, and that shift is measured to get the velocity, usually by mixing with a wave of known frequency or ...
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Why do we even need RF cavities to accelerate particles?

It is important to note that the electric scalar potential $\phi$, expressed in unit of volts, is a single valued function. If there is a downhill that accelerates the positive particle, there is ...
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Why do we even need RF cavities to accelerate particles?

The reason they'd decelerate is that the space beyond the positive electrode is, in a practical experiment, surrounded by "grounded" stuff (beam pipe, etc.). So, there's effectively a second ...
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Why do we even need RF cavities to accelerate particles?

The key limitation for using a constant electric field (i.e. DC acceleration) is that all materials have an intrinsic breakdown electric field where insulators stop being insulators (true even for air ...
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5 votes

Why do we even need RF cavities to accelerate particles?

You are absolutely right. It would be sufficient. But, particle accelators are technical devices and as such they are created using various restraints and optimized according to these restraints. It ...
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