Featured Research

from universities, journals, and other organizations

New player in electron field emitter technology makes for better imaging and communications

Date:
March 8, 2013
Source:
National Institute of Standards and Technology (NIST)
Summary:
Scientists have built a practical, high-efficiency nanostructured electron source. This new, patent-pending technology could lead to improved microwave communications and radar, and more notably to new and improved X-ray imaging systems for security and healthcare applications.

NIST's silicon carbide field emitter produces a flow of electrons comparable to hot sources, but without the need for heat. By dissolving much of the material away to make a porous structure with a large surface area, NIST scientists ensured that as an electron emission point on an individual spike wears out, another is available to take its place, making the array more durable as a whole.
Credit: Sharifi/NIST

Scientists at the National Institute of Standards and Technology (NIST) and the University of Maryland, College Park, have built a practical, high-efficiency nanostructured electron source. Described in the journal Nanotechnology, this new, patent-pending technology could lead to improved microwave communications and radar, and more notably to new and improved X-ray imaging systems for security and health-care applications.

Related Articles


While thermionic electron sources such as the hot filaments inside cathode ray tubes have largely been replaced by LEDs and liquid crystals for display screens and televisions, they are still used to produce microwaves for radar and X-rays for medical imaging. Thermionic sources use an electric current to boil electrons off the surface of a wire filament, similar to the way an incandescent light bulb uses an electric current to heat a wire filament until it glows.

And like an incandescent light bulb, thermionic sources are generally not very energy efficient. It takes a lot of power to boil off the electrons, which spew in every direction. Those that aren't lost have to be captured and focused using a complicated system of electric and magnetic fields. Field emission electron sources require much less power and produce a much more directional and easily controllable stream of electrons.

To build their field emission source, the NIST team took a tough material -- silicon carbide -- and used a room-temperature chemical process to make it highly porous like a sponge. They then patterned it into microscopic emitting structures in the shape of pointed rods or sharp-edged fins. When an electric field is applied, these novel field emitters can produce an electron flow comparable to a thermionic source but without all the disadvantages -- and with many advantages.

According to co-inventor Fred Sharifi, the new field emitters have inherently fast response times compared with thermionic sources, and the absence of heat makes it easier to create arrays of sources. Moreover, the porous nanostructure of the emitters makes them very reliable. Even if the emitter surface wears away during use -- a common problem -- the newly exposed material continues to work just as well.

Sharifi says that the NIST field emitters hold the potential to enhance the resolution and quality of X-ray images and allow for new modes of detection.

"X-ray images are based on the density of the material being examined, which limits their ability to see certain types of materials, including some types of explosives," says Sharifi. "Our field emitter will let us see not just that something is there, but, because we can build large arrays and place them at different angles, we can identify the material in question by looking at how the X-rays coming from different directions scatter from the object."


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. Myung-Gyu Kang, Henri J Lezec, Fred Sharifi. Stable field emission from nanoporous silicon carbide. Nanotechnology, 2013; 24 (6): 065201 DOI: 10.1088/0957-4484/24/6/065201

Cite This Page:

National Institute of Standards and Technology (NIST). "New player in electron field emitter technology makes for better imaging and communications." ScienceDaily. ScienceDaily, 8 March 2013. <www.sciencedaily.com/releases/2013/03/130308143850.htm>.
National Institute of Standards and Technology (NIST). (2013, March 8). New player in electron field emitter technology makes for better imaging and communications. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2013/03/130308143850.htm
National Institute of Standards and Technology (NIST). "New player in electron field emitter technology makes for better imaging and communications." ScienceDaily. www.sciencedaily.com/releases/2013/03/130308143850.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
How Sony Hopes To Make Any Glasses 'Smart'

How Sony Hopes To Make Any Glasses 'Smart'

Newsy (Dec. 17, 2014) Sony's glasses module attaches to the temples of various eye- and sunglasses to add a display and wireless connectivity. Video provided by Newsy
Powered by NewsLook.com
Los Angeles Police To Receive 7,000 Body Cameras

Los Angeles Police To Receive 7,000 Body Cameras

Newsy (Dec. 17, 2014) Los Angeles Mayor Eric Garcetti announced the cameras will be distributed starting Jan. 1. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins