Modeling of a compact terahertz source based on the two-stream instability.
type: CreativeWork
description: THz radiation straddles the microwave and infrared bands of the electromagnetic spectrum, thus combining the penetrating power of lower-frequency waves and imaging capabilities of higher-energy infrared radiation. THz radiation is employed in various fields such as cancer research, biology, agriculture, homeland security, and environmental monitoring. Conventional vacuum electronic sources of THz radiation (e.g., fast- and slow-wave devices) either require very small structures or are bulky and expensive to operate. Optical sources necessitate cryogenic cooling and are presently capable of producing milliwatt levels of power at THz frequencies. We propose a millimeter and sub-millimeter wave source based on a well-known phenomenon called the two-stream instability. The two-beam source relies on low-energy and low-current electron beams for operation. Also, it is compact, simple in design, and does not contain expensive parts that require complex machining and precise alignment. In this dissertation, we perform 2-D particle-in-cell (PIC) simulations of the interaction region of the two-beam source. The interaction region consists of a beam pipe of radius r_a and two electron beams of radius r_b co-propagating and interacting inside the pipe. The simulations involve the interaction of unmodulated (no initial energy modulation) and modulated (energy-modulated, seeded at a given frequency) electron beams. In addition, both cold (monoenergetic) and warm (Gaussian) beams are treated. Using PIC simulations, electromagnetic radiation is demonstrated over the frequency range 0.03 - 1 THz. The two-beam source is found to possess an extremely wide gain bandwidth (over a decade in frequency) from the microwave to the far infrared region of the electromagnetic spectrum. Moreover, the gain obtained is impressive. For example, the interaction of two 0.7-mm and 0.5-A electron beams with energies 20 keV and 16.95 keV (typical in this dissertation) yields the value of gain of 0.35 dB…
abstract: THz radiation straddles the microwave and infrared bands of the electromagnetic spectrum, thus combining the penetrating power of lower-frequency waves and imaging capabilities of higher-energy infrared radiation. THz radiation is employed in various fields such as cancer research, biology, agriculture, homeland security, and environmental monitoring. Conventional vacuum electronic sources of THz radiation (e.g., fast- and slow-wave devices) either require very small structures or are bulky and expensive to operate. Optical sources necessitate cryogenic cooling and are presently capable of producing milliwatt levels of power at THz frequencies. We propose a millimeter and sub-millimeter wave source based on a well-known phenomenon called the two-stream instability. The two-beam source relies on low-energy and low-current electron beams for operation. Also, it is compact, simple in design, and does not contain expensive parts that require complex machining and precise alignment. In this dissertation, we perform 2-D particle-in-cell (PIC) simulations of the interaction region of the two-beam source. The interaction region consists of a beam pipe of radius r_a and two electron beams of radius r_b co-propagating and interacting inside the pipe. The simulations involve the interaction of unmodulated (no initial energy modulation) and modulated (energy-modulated, seeded at a given frequency) electron beams. In addition, both cold (monoenergetic) and warm (Gaussian) beams are treated. Using PIC simulations, electromagnetic radiation is demonstrated over the frequency range 0.03 - 1 THz. The two-beam source is found to possess an extremely wide gain bandwidth (over a decade in frequency) from the microwave to the far infrared region of the electromagnetic spectrum. Moreover, the gain obtained is impressive. For example, the interaction of two 0.7-mm and 0.5-A electron beams with energies 20 keV and 16.95 keV (typical in this dissertation) yields the value of gain of 0.35 dB…
author: Svimonishvili, Tengiz
language: English
date published: 2011-08-31T07:00:00Z
date modified: 2026-07-24T05:27:25Z
provider: University of New Mexico
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of New Mexico