Masters Theses


"A distributed flat panel x-ray source is designed as an alternative for medical and industrial imaging fields. The distributed x-ray source corresponds to a two dimensional array of micro (~100μm) x-ray cells similar in format to a field emission display. In this paper the electron field emission characteristics of a single of the proposed micro-sized x-ray cells are simulated. The field electron emission from the CNTs-based cathode is simulated using the Particle-In-Cell code OOPIC Pro. The electron source is simulated as a triode structure, composed of an emitting cathode, extracting grid and anode. The possibility of using focusing lenses to control the trajectory of emitted electrons is evaluated as well. The CNT emitters are modeled as pure Fowler-Nordheim emitters. The field emission characteristics were analyzed for extracting voltages between 25 V and 70 V and accelerating voltages between 30 kV and 120kV. Under these conditions, JFN-V curves, energy distributions and electron distributions at the anode surface were determined. Electron trajectories were determined as well. When no focusing structures were employed, electron trajectories were found to be divergent. When focusing structures were included in the triode structure, the emitted electrons could be made to converge at the anode. In the focused cases, a dependency between the focal spot size and the extracting grid voltage was found. Results indicate an early feasibility of the proposed device to be employed as electron source in the proposed distributed flat panel x-ray source"--Abstract, page iii.


Castaño, Carlos H.

Committee Member(s)

Usman, Shoaib
Mueller, Gary Edward, 1954-


Nuclear Engineering and Radiation Science

Degree Name

M.S. in Nuclear Engineering


University of Missouri Research Board


Missouri University of Science and Technology

Publication Date

Spring 2011


viii, 72 pages


© 2011 Chrystian Mauricio Posada Arbeláez, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Electrons -- Emission
Field emission
Flat panel displays
X-rays -- Instruments -- Design

Thesis Number

T 9854

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