Electron gun and apparatus incorporating the same

An electron gun comprising:

• an electron emission element arranged to be activated to emit electron beam;
• an electrode arranged to be electrically connected with a power supply to accelerate the emitted electron beam;
• a control element arranged to be electrically connected with the power supply to provide an electric field to control emission of electron beams from the electron emission element;
• and
• a control circuit electrically connected with the control element for changing the electric field provided by the control element;
• wherein the control circuit is arranged to provide a variable resistance for changing the electric field provided by the control element;
• and
• wherein the control circuit comprises a plurality of resistors each connected with a respective switch that is respectively controlled to selectively open and close to change an equivalent resistance provided by the plurality of resistors.

An electron gun comprising:

• an electron emission element arranged to be activated to emit electron beam;
• an electrode arranged to be electrically connected with a power supply to accelerate the emitted electron beam;
• a control element arranged to be electrically connected with the power supply to provide an electric field to control emission of electron beams from the electron emission element;
• a control circuit electrically connected with the control element for changing the electric field provided by the control element;
• an actuator operable by a user to provide an input to change the electric field provided by the control element;
• and
• a controller, operably connected with the actuator and the control circuit, for controlling the control circuit based on the received input.

An electron gun comprising:

• an electron emission element arranged to be activated to emit electron beam;
• an electrode arranged to be electrically connected with a power supply to accelerate the emitted electron beam;
• a control element arranged to be electrically connected with the power supply to provide an electric field to control emission of electron beams from the electron emission element;
• a control circuit electrically connected with the control element for changing the electric field provided by the control element;
• a detector for detecting one or more properties of the emitted electron beam;
• and
• a controller, operably connected with the detector and the control circuit, for controlling the control circuit based on the one or more detected properties.