Hello,

In thermal emission electrons are emitted from the cathode as a result of high temperature. The current density that can be delivered depends largely on the temperature. Most metals have a boiling point that is so low that it sets a limit to the permissible temperature.

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Hello there

Yes they are emitted from a cathode and the better explanation is that a cathode is an electrode in a vacuum tube or any other vacuum system and is a metal surface which emits electrons into the evacuated space of any tube. As you must be knowing that the negatively charged electrons are attracted to the positive nuclei of the metal atoms so they normally stay inside the metal and require energy to leave it.

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Thank you!