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How are electrons produced for use in particle accelerators?
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particle accelerator
The accelerator is a large-diameter tube within which an electric field oscillates at a high radio frequency. Within the accelerator tube are smaller diameter metallic drift tubes, which are carefully sized and spaced to shield the protons from decelerating oscillations of the electric field. In the spaces between the drift tubes, the electric field is oriented properly to accelerate the protons in their direction of travel.
Electrons used in particle accelerators are typically produced using a device known as an electron gun.1
This process relies on thermionic emission, where a cathode (a negative electrode) is placed within a vacuum and heated until the thermal energy causes electrons to break away from the atoms of the cathode material. Once emitted, these negatively charged electrons are attracted toward a positive electrode (anode) and pass through a hole in it to enter the accelerator.12
The electron gun itself functions as a simple, initial accelerator, as the electrons are propelled by an electric field created by a voltage typically ranging between 50,000 and 150,000 volts.1