Properties of microscopic vacuum electronic devices - verkefni lokið
Fréttatilkynning verkefnisstjóra
Vacuum tubes have a long and distinguished history in electronics. Although they have been mostly replaced by solid state devices in consumer electronics, primarily due to cost issues, they still have an important role to play, particularly in generating radiation at high frequency and high power.
Microwave ovens, high power radar and space-communication systems all use vacuum electronic technology. The revolution in modern fabrication techniques have made it possible to manufacture vacuum electronic systems on the nano- and microscale. This has opened up exciting new possibilities for vacuum based devices, where their many inherent advantages over solid state electronics can be enjoyed at previously unheard of cost.
Heiti verkefnis: Properties
of microscopic vacuum electronic devices
Verkefnisstjóri: ágúst Valfells, Háskólanum í Reykjavík
Tegund styrks: Verkefnisstyrkur
Styrkár: 2012-2014
Fjárhæð styrks: 18,837 millj. kr.
Tilvísunarnúmer Rannís: 12000902
There are significant differences between vacuum electronics devices on micro- and nanoscales and their macroscopic counterparts. In this project we have analyzed some of the fundamental properties of miniature vacuum electronic devices by means of analysis and computer simulation. We have developed a molecular dynamics based code that lets us run very high-fidelity simulations of electron dynamics in vacuum diodes with accurate emission physics included. Use of this code has led to the discovery of a novel mechanism for space-charge induced bunching of photoemitted electrons in a vacuum microdiode. The bunching manifests as an alternating current arriving at the anode with a frequency on the order of Terahertz. The frequency range can be set by changing the area of emission on the cathode, and the frequency can be tuned simply by varying the applied electric field across the diode gap. We have also found that arrays of such emitters can be synchronized to produce higher levels of power at a given frequency, and that this type of diode may even be operated at room temperature.
Furthermore we have succesfully modelled field emission with our molecular dynamics code and have been able to identify temporal and geometric effects in field emitted current from a metal surface. Other work done in this project has been to identify new scaling laws for space-charge limited current from planar, cylindrical and spherical geometry.
The space-charge bunching mechanism that was discovered could offer a valuable means of generating tunable THz radiation from low-cost compact devices. Experimental work is being planned to verify the results from computer simulations and analysis. If the results are favorable, there are intriguing possibilities for device development that would help fill up the so called „Terahertz gap“. The molecular dynamics code has a number of applications ranging from basic understanding of electron dynamics, to design of field emitter arrays with optimal charged particle beam characteristics in mind.
This work has resulted in the development of software for high-resolution, molecular dynamics based simulation of electron beams including detailed emission physics, one Ph.D. thesis, one masters thesis, and five papers in ISI scientific journals (with a sixth paper in preparation).
