Electron gun, electron beam applicator, emission axis verification method for electron beam emitted from photocathode, and emission axis alignment method for electron beam emitted from photocathode

An emission axis verification method for an electron beam emitted from a photocathode in a device including

• a light source,
• a photocathode configured to emit an electron beam in response to receiving light from the light source,
• an anode,
• an intermediate electrode arranged between the photocathode and the anode,
• an electron beam shielding member configured to block a part of an electron beam,
• a measurement unit configured to measure an intensity of an electron beam blocked by the electron beam shielding member, and
• an electron beam emission direction deflector arranged between the anode and the electron beam shielding member and configured to change a position where an electron beam reaches the electron beam shielding member, the emission axis verification method comprising:
• a first electron beam emission step of emitting an electron beam in a first state by irradiating the photocathode with excitation light when electric fields between the cathode and the intermediate electrode and between the intermediate electrode and the anode are in a first state;
• a first electron beam intensity change measurement step of measuring a change in intensity of a first electron beam blocked by the electron beam shielding member while changing a position of the first electron beam reaching the electron beam shielding member by using the electron beam emission direction deflector;
• a second electron beam emission step of emitting an electron beam in a second state by irradiating the photocathode with excitation light when electric fields between the cathode and the intermediate electrode and between the intermediate electrode and the anode are in a second state;
• a second electron beam intensity change measurement step of measuring a change in intensity of a second electron beam blocked by the electron beam shielding member while changing a position of the second electron beam reaching the electron beam shielding member by using the electron beam emission direction deflector;
• and
• a misalignment verification step of verifying whether or not an electron beam emitted from the photocathode is misaligned from a designed center axis by comparing a measurement result of the first electron beam intensity change measurement step with a measurement result of the second electron beam intensity change measurement step.