Electron gun using virtual source method
Provided is an electron gun using a virtual source method that may have a high angular current density, a narrow energy distribution, and stable electron emission characteristics by forming a virtual source inside a thermal electron source (LaB 6 , CeB 6 )-based emitter emitting an electron beam.
1 . An electron gun using a virtual source method, the electron gun comprising:
an emitter configured to emit an electron beam to the outside;
a suppressor electrode disposed at a position behind a tip of the emitter based on a direction of emission of the electron beam and surrounding the emitter; and
an extraction electrode disposed on one side of the suppressor electrode,
wherein the emitter has a virtual source formed inside an interior region of the emitter,
wherein the suppressor electrode is configured to suppress electron emission from regions other than the tip and to induce formation of the virtual source inside the emitter,
wherein sizes of holes of the suppressor electrode and the extraction electrode are less than or equal to 5 mm in diameter,
wherein a distance between the suppressor electrode and the extraction electrode is greater than or equal to 0.5 mm and less than or equal to 2 mm, and
wherein the suppressor electrode comprises a first surface and a second surface inclined relative to the first surface to define a tapered tip of the suppressor electrode, the tapered tip of the suppressor electrode having a first thickness defined by a distance between the first surface and the second surface in the direction of emission and gradually decreasing toward a distal end of the suppressor electrode; and
wherein the extraction electrode comprises a third surface opposing the first surface and a fourth surface inclined relative to the third surface to define a tapered tip of the extraction electrode, the tapered tip of the extraction electrode having a second thickness defined by a distance between the third surface and the fourth surface in the direction of emission and gradually decreasing toward a distal end of the extraction electrode.
2 . The electron gun of claim 1 , wherein the emitter is formed of lanthanum hexaboride (LaB6) or cerium hexaboride (CeB6).
3 . The electron gun of claim 1 , wherein a diameter of a tip of the emitter is less than or equal to 50 μm.
4 . The electron gun of claim 1 , wherein at least one of the suppressor electrode and extraction electrode is formed of at least one material among stainless steel (SUS), aluminum, molybdenum, titanium, and tantalum.