Electron Emitting Apparatus and Method for Emitting Electrons

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This invention describes an apparatus and method for emitting electrons using a nanowire cathode made of a metal hexaboride (preferably LaB6) inside a vacuum chamber. The key innovation is triggering electron emission from the nanowire's apex using a precisely directed laser beam, instead of—or in addition to—conventional high-voltage field emission. The laser-induced emission occurs when a negative potential is applied to the cathode relative to the anode. The setup can use ultrashort pulsed lasers and may include suppressor electrodes to enable higher emission currents and energies without damaging the nanowire.

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• Electron source for electron microscopes (scanning and transmission electron microscopes) to improve imaging capabilities and resolution.
• Electron guns for particle accelerators, aiding in scientific research and medical applications like cancer therapy.
• Precision electron sources in analytical instruments for materials science and nanotechnology.
• Compact and high-brightness electron emission sources in portable or advanced diagnostic devices.
• Medical imaging devices where controlled, high-brightness electron beams are desirable.
• Research tools for studying ultrafast processes at atomic or molecular scales using pulsed electron beams.

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• Enables highly stable, high-brightness electron beams with minimal emission decay over time.
• Provides a controllable and precise method to trigger electron emission using a laser, allowing for ultrafast (femtosecond) temporal resolution and synchronization with other optical systems.
• Lower energy spread and small transverse emittance of the electron beam, which translates to higher imaging resolution and beam quality.
• Capability to use a wide range of laser wavelengths (UV, visible, IR) and pulse durations for tailored electron emission profiles.
• Nanowire cathode made of LaB6 is robust and produces less contamination than traditional tungsten filaments, increasing operational lifespan and reliability.
• The laser trigger system allows for pulsed operation, opening doors to time-resolved studies and minimizing thermal load on the emitter during operation.
• Suppressor electrodes enable higher acceleration voltages, producing higher-energy electron beams without damaging the emitter, thereby increasing application versatility.

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Patent Abstract

The invention refers to an electron emitting apparatus, comprising a cathode (3) and an anode (4), both disposed in a vacuum chamber (1), where the apparatus is configured to apply a voltage difference between the cathode (3) and the anode (4) such that the cathode (3) has a negative potential (Utip) relative to the anode (4), the cathode (3) comprising a nanowire made of metal hexaboride, the nanowire having an apex for emitting electrons therefrom. The invention is characterized in that the electron emitting apparatus comprises a laser device (7, 8) for generating a laser beam (LB) and directing the laser beam (LB) onto the apex of the nanowire, where the laser beam (LB) triggers the emission of electrons from the apex when the cathode (3) has the negative potential (Utip) relative to the anode (4).