An electron source according to the present disclosure includes a columnar portion made of a first material having an electron emission characteristic; and a tubular portion that is disposed to surround the columnar portion and made of a second material having a higher work function than the first material, wherein a hole that extends in a direction from one end face toward the other end face and has a substantially circular cross-sectional shape is formed in the tubular portion, and the columnar portion has a substantially triangular or substantially quadrangular cross-sectional shape and is fixed to the tubular portion in an abutting engagement with an inner surface of the hole.

A monolithic graphite heater for heating a thermionic electron cathode includes first and second electrically conductive arms, each one of the first and second electrically conductive arms having an electrode mount at a proximal end, a thermal apex at a distal end, and a transitional region between the electrode mount and the thermal apex; a cathode mount electrically and mechanically coupling each thermal apex to form a maximum Joule-heating region at or adjacent the cathode mount and decreasing Joule heating along each transitional region; and a press-fit aperture formed in the cathode mount, the press-fit aperture sized to receive at least a portion of the thermionic electron cathode for facilitating thermionic emission produced therefrom in response to operative heat power generation provided by the maximum Joule-heating region.

A monolithic graphite heater for heating a thermionic electron cathode includes first and second electrically conductive arms, each one of the first and second electrically conductive arms having an electrode mount at a proximal end, a thermal apex at a distal end, and a transitional region between the electrode mount and the thermal apex; a cathode mount electrically and mechanically coupling each thermal apex to form a maximum Joule-heating region at or adjacent the cathode mount and decreasing Joule heating along each transitional region; and a press-fit aperture formed in the cathode mount, the press-fit aperture sized to receive at least a portion of the thermionic electron cathode for facilitating thermionic emission produced therefrom in response to operative heat power generation provided by the maximum Joule-heating region.

A monolithic graphite heater for heating a thermionic electron cathode includes first and second electrically conductive arms, each one of the first and second electrically conductive arms having an electrode mount at a proximal end, a thermal apex at a distal end, and a transitional region between the electrode mount and the thermal apex; a cathode mount electrically and mechanically coupling each thermal apex to form a maximum Joule-heating region at or adjacent the cathode mount and decreasing Joule heating along each transitional region; and a press-fit aperture formed in the cathode mount, the press-fit aperture sized to receive at least a portion of the thermionic electron cathode for facilitating thermionic emission produced therefrom in response to operative heat power generation provided by the maximum Joule-heating region.

A monolithic graphite heater for heating a thermionic electron cathode includes first and second electrically conductive arms, each one of the first and second electrically conductive arms having an electrode mount at a proximal end, a thermal apex at a distal end, and a transitional region between the electrode mount and the thermal apex; a cathode mount electrically and mechanically coupling each thermal apex to form a maximum Joule-heating region at or adjacent the cathode mount and decreasing Joule heating along each transitional region; and a press-fit aperture formed in the cathode mount, the press-fit aperture sized to receive at least a portion of the thermionic electron cathode for facilitating thermionic emission produced therefrom in response to operative heat power generation provided by the maximum Joule-heating region.

This method of producing a negative electrode includes a step of adjusting a heat transfer coefficient between a leg portion and a fixing portion so that at least one of leg portions and the other leg portions become different in the heat transfer coefficient by deforming the plurality of fixing portions by applying pressure to the plurality of fixing portions from the outside thereof to fix the leg portions to the fixing portions.

This method of producing a negative electrode includes a step of adjusting a heat transfer coefficient between a leg portion and a fixing portion so that at least one of leg portions and the other leg portions become different in the heat transfer coefficient by deforming the plurality of fixing portions by applying pressure to the plurality of fixing portions from the outside thereof to fix the leg portions to the fixing portions.

The present invention provides an emitter made of a hafnium carbide (HfC) single crystal that stably emits electrons with high efficiency, a method for manufacturing the emitter, and an electron gun and an electronic device using the emitter. An emitter according to an embodiment of the present invention is an emitter including a nanowire, in which the nanowire is made of the hafnium carbide (HfC) single crystal, at least an end of the nanowire through which electrons are to be emitted is coated with hafnium oxycarbide (HfC.sub.1-xO.sub.x: 0<x?0.5), and a field electron emission pattern of the end obtained by a field emission microscope (FEM) is a single spot.

This method of producing a negative electrode includes a step of adjusting a heat transfer coefficient between a leg portion and a fixing portion so that at least one of leg portions and the other leg portions become different in the heat transfer coefficient by deforming the plurality of fixing portions by applying pressure to the plurality of fixing portions from the outside thereof to fix the leg portions to the fixing portions.

This method of producing a negative electrode includes a step of adjusting a heat transfer coefficient between a leg portion and a fixing portion so that at least one of leg portions and the other leg portions become different in the heat transfer coefficient by deforming the plurality of fixing portions by applying pressure to the plurality of fixing portions from the outside thereof to fix the leg portions to the fixing portions.