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Design of a Novel 3D Field Emission Electron Source for High Power X-Ray Tube

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J Zhang

Y Xu, D Li, J Zhang*, Shanghai Advanced Research Institute, Shanghai, Shanghai

WE-C-103-3 Wednesday 10:30AM - 12:30PM Room: 103

Purpose:
Field emission electron sources today have shown great potentials in various medical imaging applications, such as computed tomography (CT), which demands extremely high emission current. High emission current can be achieved by raising the gate voltage at the expense of increased cathode instability and reduced cathode life. This paper presents the design of a new 3D field emission electron source that has the potential to overcome the limits of conventional field emission cathode in emission current and cathode life.

Methods:
The 3D cathode design is based on a semi-enclosed rectangular cavity structure, with one face open to the anode for electron beam emission. All the inner faces of the cavity including four sides and one bottom are set to be the emission surfaces. The 3D cathode has a depth (cavity height) of 5mm along the source axial direction, along with a 10mmx10mm electron beam aperture that is 10mm away from the anode.

Results:
The performance of both the 3D and conventional 2D cathode was evaluated using the commercial software package CST Studio Suite, under the same operating condition. We have demonstrated that the total emission current of the 3D cathode is 2.4 times the one of the 2D cathode, from a total 3 times emission surface area. The slightly reduced electron transmission rate in the 3D cathode is due to the electron collision inside the cavity structure.

Conclusion:
We present a novel field emission electron source design based on a 3D semi-enclosed cavity structure, by utilizing the multiple inner surfaces of the cavity for electrons emission. The 3D cathode has transverse dimensions the same as a conventional single surface 2D cathode, but larger emission area due to its extended space. The 3D cathode design was demonstrated to have the capability of providing much higher cathode current density.

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