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Electron particle accelerator

Experimenting with speeding electrons (draft)

When a sufficient high voltage is applied across two electrodes inside a vacuum chamber, electrons are liberated from the negative charged electrode (cathode) and stream across the vacuum to the positively charged electrode (anode) this stream of electrons is commonly called cathode rays.

Vacuum Chamber

This high voltage accelerates electrons to a high velocity (about 59,000 km/s, or about 20 percent of the speed of light at a voltage of 10 kV) due to their low-mass. When they get to the anode at the other end of the chamber, they have so much momentum many fly past the anode and strike the wall of the chamber. When they strike the wall of chamber they knock the orbital electrons of the atoms in the wall into a higher energy level. When the electrons fall back to their original energy level, it emits a photon (light) such as a green glow in the case of a glass vacuum chamber.

If a few atoms of gas remain in the chamber this will cause the cavity between the electros to glow. Although this useful in cold cathode applications, too much gas has the an unwanted affect as electrons will only travel a short distance before hitting a gas molecule. So the current of electrons is moved in a slow diffusion process, constantly colliding with gas molecules and never gaining much energy.</p>

Vacuum Chamber with traces of gas

If the cathode is heated, electrons will flow more really, at lower voltages at increased current, in much higher vacuum because the added thermal energy overcomes the binding potential of the atoms in the metal cathode this is called thermionic emmission.

thermionic emission

With a reliable stream of electrons it is possible to focus the electrons into a beam, accelerate it and even bend the beam using an electrostatic or magnetic field.

Electron Gun Electrostatic Deflection                  Electron Gun Magnetic Deflection