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FYRIRLESTRAMARAÞON HR 2011 | RU LECTURE MARATHON 2011 Ágúst Valfells Science and Engineering SIZE MATTERS –ELECTRON BEAMS AT THE MICROSCALE.

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Presentation on theme: "FYRIRLESTRAMARAÞON HR 2011 | RU LECTURE MARATHON 2011 Ágúst Valfells Science and Engineering SIZE MATTERS –ELECTRON BEAMS AT THE MICROSCALE."— Presentation transcript:

1 FYRIRLESTRAMARAÞON HR 2011 | RU LECTURE MARATHON 2011 Ágúst Valfells Science and Engineering SIZE MATTERS –ELECTRON BEAMS AT THE MICROSCALE

2 www.hr.is solid state integrated circuit vacuum electronics high power microwaves Solid state Vacuum electronics 110 100 Frequency[GHz] 10 1 10 2 10 3 10 4 10 5 CW power [W] vacuum tubes tubes are expensive to make must maintain vacuum conditions integrated circuits are inexpensive solid state electronics put limit on frequency and efficiency

3 www.hr.is vacuum microelectronics Credit: Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley nanotube radio Credit Paul Scherrer Institute field emission array

4 www.hr.is possible advantages of vacuum microelectronics high efficiency due to limited interaction with bulk structure tolerance of high temperature and radiation short path length decreases vacuum requirements small length scales indicate possible high frequency f ~ 1 / L rapid switching via field emission

5 www.hr.is electron beams – emission Thermionic emission. Photoemission. wikipedia Field emission Field emission is due to tunneling of electrons through the potential barrier. It is the dominant emission mechanism at high field strength. Local enhancment of the electric field can lead to higher emission density. Accurate assesment of surface field is difficult –much fudging.

6 www.hr.is surface irregularities Credit Joonil Seog electric field is enhanced at protrusions surface uniformity decreases at shorter length scales variations in composition are also important

7 www.hr.is electron beams - dynamics electrons in vacuum region interact with surrounding structure electrons interact with each other - nonlinearity THz bunching due to space-charge limited emission. An intriguing possibility for generating radiation. -+

8 www.hr.is issues of interest at the vacuum scale emission physics: i-v characteristics; energy and angular distribution of electrons from surface; accurate modeling –needs and limitations. beam dynamics: emittance and brightness; long range and short range Coulomb interaction; transit time, frequency response. electron backscattering and secondary electron emission. quantum effects. irregularity of surfaces; shot noise; cavity Q; surface roughness and skin depth

9 www.hr.is computational vacuum microelectronics at RU Microscale works to our advantage – full fidelity modeling 1 nm10 nm 50 nm


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