The present invention relates to an electron gun cathode mount adapted at one end to secure a thermionic cathode and at the other end to be connected to an attachment member, wherein the electron gun cathode mount is structured so as to be capable of, when in use, reducing heat transfer from the thermionic cathode to the attachment member, and the material forming the electron gun cathode mount has a thermal conductivity of less than 10 Wm.sup.1K.sup.1 at the operating temperature of the thermionic cathode in a direction from the thermionic cathode to the attachment member. The present invention also relates to an electron gun assembly having the electron gun cathode mount installed therein.

An object is to provide an electron beam applicator suitable for an electron gun having a photocathode and an electron beam emission method in the electron beam applicator. The object can be achieved by an electron beam applicator including: an electron gun section; a main body section; and a control unit. The electron gun section includes a light source, a photocathode that emits an electron beam in response to receiving excitation light emitted from the light source, and an anode. The main body section includes an objective lens that converges an electron beam emitted from the electron gun section. The control unit controls at least convergence power of the objective lens in accordance with a size of an electron beam emitted from the photocathode.

An electron gun includes a cathode to emit electron beams, an anode configured to include a surface which faces the cathode and in which there are formed the first opening for passing the electron beams from the cathode and at least one second opening at a position different from that of the first opening and in the same surface as the first opening, and maintained to be a relatively positive potential with respect to a cathode potential, a limiting aperture substrate at the downstream side of the anode with respect to an advancing direction of the electron beams, formed with the third opening for passing the electron beams and limiting passage of a portion of the electron beams, and a Wehnelt electrode between the cathode and the anode, applied with a relatively negative potential with respect to an anode potential.

According to one aspect of the present invention, an electron beam adjustment method, includes: setting, to a predetermined value, a temperature of a cathode in a thermal electron source; changing a bias voltage applied to a Wehnelt electrode while maintaining the temperature of the cathode at the predetermined value; measuring an emission current in a case that the bias voltage is changed while maintaining the temperature of the cathode at the predetermined value; and calculating a determination parameter based on an amount of change in the emission current in a case that the bias voltage is changed, wherein each of the changing of the bias voltage, the measuring of the emission current, and the calculating of the determination parameter is repeated within a range where the determination parameter does not exceed a threshold value while maintaining the temperature of the cathode at the predetermined value.

This invention provides a charged particle source, which comprises an emitter and means fo generating a magnetic field distribution. The magnetic field distribution is minimum, about zero, or preferred zero at the tip of the emitter, and along the optical axis is maximum away from the tip immediately. In a preferred embodiment, the magnetic field distribution is provided by dual magnetic lens which provides an anti-symmetric magnetic field at the tip, such that magnetic field at the tip is zero.

A method for manufacturing an electron source according to the present disclosure includes steps of: (A) preparing a first member provided with a columnar portion made of a first material having an electron emission characteristic, (B) preparing a second member which has a higher work function and a lower strength than the first material, and in which a hole is formed extending in a direction from one end surface toward the other end surface, and (C) pushing the columnar portion into the hole in the second member, wherein the first member has a cross-sectional shape that is dissimilar to the cross-sectional shape of the hole; and in the step (C), by pressing the columnar portion into the hole, a portion of a side surface of the columnar portion scrapes the inner surface of the hole and bites into the second member, thereby fixing the columnar portion to the second member.