電子在加速後一定會發射電磁波嗎？

2012-02-05 8:45 pm

The continuous spectrum of X-ray originates from the deceleration of fast-moving electrons because the deceleration of electrons is capable of producing electromagnetic waves. But why don't electrons produce electromagnetic waves when they are being accelerated from a cathode to an anode across a high voltage (e.g.10kV) ?

回答 (1)

天同

2012-02-05 9:48 pm

✔ 最佳答案

When an electron deccelerates, it loses kinetic energy. Accoding to classical electromagentic theory, the energy is released in the form of electromagentic waves.

But when the electron accelerates, it actually increases in kinetic energy. The increase in energy comes from the electric field between the anode and cathode. There is no energy released from the electron.

In fact, in medical linear accelerators, electrons are forced to accelerate using microwave. Under that situation, the electron absorbs energy from the microwave and gains in kinetic energy. This is just the reverse process of that occurs in a conventional x-ray tube.

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