A Compact X-ray Generator Using a Nanostructured Field Emission Cathode and a Microstructured Transmission Anode

13th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications

物理学;能源学

Cheng, S.^1 ; Hill, F.A.^1 ; Heubel, E.V.^1 ; Quez-García, L. F. Velás^1

Microsystems Technology Laboratories, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, United States^1

关键词: Background radiation;    Biological tissues;    Bone structure;    Field emitter;    Lower voltages;    Nano-structured;    Spectral line width;    X ray generators;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/476/1/012016/pdf
DOI  :  10.1088/1742-6596/476/1/012016

来源: IOP

【 摘 要 】

We report the design, fabrication, and preliminary characterization of a compact X-ray generator for improved X-ray absorption imaging that uses a nanostructured field emission cathode (FEC) as the electron source and a microstructured transmission anode as the X-ray generating element. FECs consume less power, respond faster, and tolerate lower vacuum than thermionic cathodes used in conventional X-ray generators. The use of a transmission anode, instead of a conventional reflection anode, allows filtering of the background radiation (brems strahlung) while allowing efficient generation of X-rays at lower voltages by exciting atomic shell transitions, resulting in emission of X-rays with narrow spectral linewidth for sharper imaging of biological tissue. The fabricated FEC contains arrays of self-aligned, gated field emitters that turn on at bias voltages under 30 V and transmit 99.5% of the electrons to the anode. The FEC emits a maximum current of 1.2 μA per field emitter (588 μA total array current) at a bias voltage of 85 V. A facility is built and tested to generate X-rays with an FEC and a transmission anode. Using the facility, we obtained an X-ray absorption image of an ex-vivos ample that clearly shows softtissue and fine bone structures.