What is it about?
We have constructed an x-ray irradiation system utilizing field electrons emitted from the carbon-nanofibers (CNFs) grown on the palladium wire. The CNF electron emitter gave higher current of I ~ 1 mA, and the current was stable within 10% for a long time of t > 5000 h. The field electrons extracted from the emitter were mostly used at the acceleration voltage of Va ~ 50 kV. The x-rays radiated from the metal target (Ti, Cu, Mo, and W) were transmitted through Be-window. Under these operating conditions, the x-rays were exclusively composed of the characteristic L and K lines, and the dose rates of the x-rays were D = 2.5-14 Gy/min. In our source, the x-rays were reflected from the metal target, and the x-ray source area was determined by the slit size on the extracting gate electrode. The source area was not so small, but the x-ray source provided sufficiently sharp x-ray images.
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Why is it important?
The field-electron emitter using CNFs had simple structure, and it maintained high (and stable) intensity and long life. Utilizing the field-electron emitter, the x-rays radiated from the metal target provided sufficiently higher dose rates. The FE-type x-ray generator could be applied to study biological effect of x-rays.
Perspectives
The field electrons can be focused to a micro-size, and x-ray can be radiated from micro-area. Thus, a fine-focusing x-ray source can be constructed by using the field electron emitter. (Such x-ray source was actually reported elsewhere.)
Emeritus Professor Shigetomo Kita
Read the Original
This page is a summary of: Field-emission-type x-ray source using carbon-nanofibers, Journal of Applied Physics, March 2008, American Institute of Physics,
DOI: 10.1063/1.2894730.
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