An object is to provide an electron gun that can extend the lifetime of a photocathode. The object can be achieved by an electron gun including: a substrate having a photocathode film formed on a first face; a light source for irradiating the photocathode film with excitation light; an anode; a heater device for heating the photocathode film and/or the substrate; and an output adjustment device that adjusts a heating temperature of the heater device.

Provided is a negative ion source and a negative ion generation method capable of providing a high negative ion generation efficiency. A negative ion source includes a housing that includes: an inlet from which a sample is introduced; a plasma generation region communicated with the inlet, a plasma being generated by discharge in the plasma generation region; a negative ion generation region in which particles dissociated or excited by a reaction of the generated plasma with the sample are converted into negative ions; and an extraction port communicated with the negative ion generation region, the generated negative ions being extracted outside through the extraction port. The negative ion generation region is filled with a thermionic emission material for generating thermoelectrons by high frequency heating.

An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular; a heater; an anode being arranged to oppose the cathode; and a heat resistant member. The anode applies a positive potential relative to the cathode to extract electrons in a predetermined direction. The cathode has, in a central portion thereof, a through hole along a central axis of the cathode. The heat resistant member has a first portion to close the through hole and a second portion being positioned between the cathode and the heater.

An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular; a heater; an anode being arranged to oppose the cathode; and a heat resistant member. The anode applies a positive potential relative to the cathode to extract electrons in a predetermined direction. The cathode has, in a central portion thereof, a through hole along a central axis of the cathode. The heat resistant member has a first portion to close the through hole and a second portion being positioned between the cathode and the heater.

Various disclosed embodiments include combined heating and power modules and combined heat and power devices. In an illustrative embodiment, a combined heat and power device includes a heating system including: at least one burner; at least one igniter configured to ignite the at least one burner; a fluid motivator assembly including an electrically powered prime mover; and a heat exchanger fluidly couplable to the fluid motivator assembly. At least one thermionic energy converter has a hot shell and a cold shell, the hot shell being thermally couplable to the at least one burner, the cold shell being thermally couplable to the heat exchanger.

Various disclosed embodiments include combined heating and power modules and combined heat and power devices. In an illustrative embodiment, a combined heat and power device includes a heating system including: at least one burner; at least one igniter configured to ignite the at least one burner; a fluid motivator assembly including an electrically powered prime mover; and a heat exchanger fluidly couplable to the fluid motivator assembly. At least one thermionic energy converter has a hot shell and a cold shell, the hot shell being thermally couplable to the at least one burner, the cold shell being thermally couplable to the heat exchanger.

Disclosed embodiments include cathodes with conformal cathode surfaces, vacuum electronic devices with cathodes with conformal cathode surfaces, and methods of manufacturing the same. In a non-limiting embodiment, a cathode for a vacuum electronic device includes: a substrate having a predetermined shape; and electron emissive material disposed on at least one portion of at least one surface of the substrate, a shape of the electron emissive material conforming to the predetermined shape of the substrate.

Provided is a negative ion source and a negative ion generation method capable of providing a high negative ion generation efficiency. A negative ion source includes a housing that includes: an inlet from which a sample is introduced; a plasma generation region communicated with the inlet, a plasma being generated by discharge in the plasma generation region; a negative ion generation region in which particles dissociated or excited by a reaction of the generated plasma with the sample are converted into negative ions; and an extraction port communicated with the negative ion generation region, the generated negative ions being extracted outside through the extraction port. The negative ion generation region is filled with a thermionic emission material for generating thermoelectrons by high frequency heating.