Abstract: The disclosure relates to a detecting system including a terahertz wave source, a detector and a controlling computer. The terahertz wave source includes a terahertz reflection klystron including an electron emission unit, a resonance unit, an output unit. The electron emission unit is configured to emit electrons. The resonance unit includes a resonant cavity communicated with the electron emission unit so that the electron emission unit emit electrons into the resonant cavity. The resonant cavity of the electron emission unit opposite the cavity wall has an output aperture coupled. The output unit is communicated with the resonance unit by the output aperture coupled. The resonance unit generate terahertz wave transmit to the output unit by the output aperture coupled.

Abstract: The disclosure relates to a detecting system including a terahertz wave source, a detector and a controlling computer. The terahertz wave source includes a terahertz reflection klystron including an electron emission unit, a resonance unit, an output unit. The electron emission unit is configured to emit electrons. The resonance unit includes a resonant cavity communicated with the electron emission unit so that the electron emission unit emit electrons into the resonant cavity. The resonant cavity of the electron emission unit opposite the cavity wall has an output aperture coupled. The output unit is communicated with the resonance unit by the output aperture coupled. The resonance unit generate terahertz wave transmit to the output unit by the output aperture coupled.

Abstract: A Tera Hertz reflex klystron includes an electron emission unit, a resonant unit and an output unit. The electron emission is used to emit a plurality of electrons. The electron emission unit defines a first opening. The resonant unit comprises a resonant cavity frame. The resonant cavity frame comprises a top wall and a bottom wall and defines a resonant cavity. The top wall and the bottom wall faces with each other. The bottom wall comprises a bottom opening. The top wall comprises a top opening and at least one outputting hole. The bottom opening and the first opening are merged with each other. The output unit being configured to output Tera Hertz waves. The plurality of electrons are transferred to the output unit from the at least one outputting hole.

Abstract: A Tera Hertz reflex klystron includes an electron emission unit, a resonant unit and an output unit. The electron emission is used to emit a plurality of electrons. The electron emission unit defines a first opening. The resonant unit comprises a resonant cavity frame. The resonant cavity frame comprises a top wall and a bottom wall and defines a resonant cavity. The top wall and the bottom wall faces with each other. The bottom wall comprises a bottom opening. The top wall comprises a top opening and at least one outputting hole. The bottom opening and the first opening are merged with each other. The output unit being configured to output Tera Hertz waves. The plurality of electrons are transferred to the output unit from the at least one outputting hole.

Abstract: An ionization vacuum gauge includes a cathode, an anode and an ion collector. The ion collector component is located at one side of the anode component and spaced from the anode component. The cathode component is located at another side of the anode component and includes an electron emitter, which extends toward the anode component from the cathode component. The electron emitter includes at least one carbon nanotube wire.

Abstract: An electron emission device includes an anode, a cathode, an electron emitter structure, and an electron extraction electrode. The cathode is spaced from the anode. The electron emitter structure is electrically connected to the cathode. The electron extraction electrode is insulated from the cathode. The electron extraction electrode defines a through hole surrounded by a sidewall, and the electron emitter structure faces to the sidewall. The electron emitter structure includes a number of electron emitters extending toward the sidewall, each of the number of electron emitters includes an electron emission terminal, a first distance between each electron emission terminal and the sidewall is substantially the same, a second distance between the electron emission terminal and the anode is greater than or equal to 10 micrometers and smaller than or equal to 200 micrometers, and a pressure in the electron emission device is smaller than or equal to 100 Pascal.

Abstract: A generator includes a heat-electricity transforming device and a heat collector. The heat-electricity transforming device is configured to transform heat into electricity. The heat collector includes at least one heat absorption module. The at least one heat absorption module includes a carbon nanotube structure. The at least one heat absorption module is connected to the heat-electricity transforming device and transfers heat to the heat-electricity transforming device.

Abstract: An electron emission device includes an anode, a cathode, an electron emitter structure, and an electron extraction electrode. The cathode is spaced from the anode. The electron emitter structure is electrically connected to the cathode. The electron extraction electrode is insulated from the cathode. The electron extraction electrode defines a through hole surrounded by a sidewall, and the electron emitter structure faces to the sidewall. The electron emitter structure includes a number of electron emitters extending toward the sidewall, each of the number of electron emitters includes an electron emission terminal, a first distance between each electron emission terminal and the sidewall is substantially the same, a second distance between the electron emission terminal and the anode is greater than or equal to 10 micrometers and smaller than or equal to 200 micrometers, and a pressure in the electron emission device is smaller than or equal to 100 Pascal.

Abstract: A field emission cathode device includes a cathode electrode. An electron emitter is electrically connected to the cathode electrode, wherein the electron emitter includes a number of sub-electron emitters. An electron extracting electrode is spaced from the cathode electrode by a dielectric layer, wherein the electron extracting electrode defines a through-hole. The distances between an end of each of the sub-electron emitters away from the cathode electrode and a sidewall of the through-hole are substantially equal.

Abstract: A solar collector includes a substrate having a top surface and a bottom surface opposite to the upper surface, a sidewall, a transparent cover, and a heat-absorbing layer. The sidewall is arranged on the periphery of the top surface of the substrate. The transparent cover is disposed on the sidewall opposite to the substrate to form a sealed chamber. The heat-absorbing layer is disposed on the upper surface of the substrate and includes a carbon nanotube film having a plurality of carbon nanotubes. The carbon nanotubes in the carbon nanotube film are joined end-to-end.

Abstract: A field emission cathode device includes a cathode electrode. An electron emitter is electrically connected to the cathode electrode, wherein the electron emitter includes a number of sub-electron emitters. An electron extracting electrode is spaced from the cathode electrode by a dielectric layer, wherein the electron extracting electrode defines a through-hole. The distances between an end of each of the sub-electron emitters away from the cathode electrode and a sidewall of the through-hole are substantially equal.

Abstract: A solar collector includes a substrate having a top surface and a bottom surface opposite to the upper surface, a sidewall, a transparent cover, and a heat-absorbing layer. The sidewall is arranged on the top surface of the substrate. A transparent cover is disposed on the sidewall opposite to the substrate to form a sealed chamber with the substrate together. The heat-absorbing layer is disposed on the upper surface of the substrate and includes a carbon nanotube composite material.

Abstract: A solar collector includes a substrate having a top surface and a bottom surface opposite to the upper surface, a sidewall, a transparent cover, and a heat-absorbing layer. The sidewall is arranged on the top surface of the substrate. The transparent cover is disposed on the sidewall opposite to the substrate to form a sealed chamber with the substrate together. The heat-absorbing layer is disposed on the upper surface of the substrate and includes a carbon nanotube film having a plurality of carbon nanotubes. The carbon nanotubes in the carbon nanotube film are entangled with each other.

Abstract: A solar collector includes a substrate having a top surface and a bottom surface opposite to the upper surface, a sidewall, a transparent cover, and a heat-absorbing layer. The sidewall is arranged on the top surface of the substrate. The transparent cover is disposed on the sidewall opposite to the substrate to form a sealed chamber with the substrate together. The heat-absorbing layer is disposed on the upper surface of the substrate and includes a carbon nanotube structure.

Abstract: The present disclosure provides a field emission device. The field emission device includes an insulating substrate having a first surface, a first electrode, a second electrode, at least one cathode emitter and a secondary electron emitter. The first electrode and the second electrode are spaced from each other and are located on the first surface of the insulating substrate. The cathode emitter is electrically connected to the first electrode and spaced from the second electrode. A secondary electron emitter is spaced from the cathode emitter. The secondary electron emitter has an electron emitting surface exposed to the cathode emitter. A secondary electron emitter is spaced from the cathode emitter. The cathode emitter is oriented toward the secondary electron emitter.

Abstract: A solar collector includes a substrate having a top surface and a bottom surface opposite to the upper surface, a sidewall, a transparent cover, and a heat-absorbing layer. The sidewall is arranged on the periphery of the top surface of the substrate. Thea transparent cover is disposed on the sidewall opposite to the substrate to form a sealed chamber with the substrate together. The heat-absorbing layer is disposed on the upper surface of the substrate and includes a carbon nanotube film having a plurality of carbon nanotubes. The carbon nanotubes in the carbon nanotube film are aligned along a same direction or along different directions.

Abstract: A method for establishing a vacuum in a container includes the following steps. The container having an exhaust through hole defined therein is provided. A sealing cover including a connecting material located on the periphery of the sealing cover is provided. The sealing cover is spaced from the exhaust through hole for form at least gaps between the sealing cover and the exhaust through hole. A vacuum is established in the container. The connecting material is heated. The sealing cover covers the exhaust through hole and the connecting material is cooled. After that the container is packaged.

Abstract: An ionization vacuum gauge includes a cathode, an anode and an ion collector. The ion collector component is located at one side of the anode component and spaced from the anode component. The cathode component is located at another side of the anode component and includes an electron emitter, which extends toward the anode component from the cathode component. The electron emitter includes at least one carbon nanotube wire.

Abstract: An ion source using a field emission device is provided. The field emission device includes an insulative substrate, an electron pulling electrode, a secondary electron emission layer, a first dielectric layer, a cathode electrode, and an electron emission layer. The electron pulling electrode is located on a surface of the insulative substrate. The secondary electron emission layer is located on a surface of the electron pulling electrode. The cathode electrode is located apart from the electron pulling electrode by the first dielectric layer. The cathode electrode has a surface oriented to the electron pulling electrode and defines a first opening as an electron output portion. The electron emission layer is located on the surface of the cathode electrode and oriented to the electron pulling electrode.

Abstract: A method for making a field emission device includes the following steps. An insulative substrate is provided. An electron pulling electrode is formed on the insulative substrate. A secondary electron emission layer is formed on the electron pulling electrode. A first dielectric layer is fabricated. The first dielectric layer has a second opening to expose the secondary electron emission layer. A cathode plate having an electron output portion is provided. An electron emission layer is formed on part surface of the cathode plate. The cathode plate is placed on the first dielectric layer. The electron output portion and the second opening have at least one part overlapped, and at least one part of the electron emission layer is oriented to the secondary electron emission layer via the second opening.