Featured Research

from universities, journals, and other organizations

Getting to know the Sun advances fusion research: Coaxial helicity injection could make fusion reactors cheaper

Date:
November 9, 2010
Source:
American Physical Society
Summary:
A method known as coaxial helicity injection could eliminate an expensive component in tokamaks, leading to a more economical fusion reactor.

Researchers at the Princeton Plasma Physics Laboratory have successfully used Coaxial Helicity Injection (CHI) to generate plasma current and couple it to a conventional current generation method at the National Spherical Torus Experiment (NSTX) fusion experiment. After coupling, the combined process generated 1 million amperes of current using 40 percent less energy than needed to generate this current using the conventional means by itself, thus demonstrating that a high-quality initial magnetic configuration was produced by CHI.

Plasma confinement devices based on the tokamak concept rely on a solenoid through the center of the device to generate the initial current. Because the solenoid is used as an electrical transformer, its pulse length is limited in duration and it cannot sustain the initial current indefinitely in a steady-state reactor. Thus a method to eliminate the solenoid would remove a large component from the center of the tokamak, making the device simpler and less expensive. This allows the freed space in the center to be used in optimizing the device, making the tokamak more efficient by producing a magnetic configuration similar to that in a spherical tokamak.

CHI generates plasma currents by producing a magnetic bubble using magnetic reconnection. This is analogous to producing a soap bubble by blowing air through a ring dipped in soap solution. During CHI, currents are driven along magnetic filaments so that the resulting magnetic forces overcome the magnetic filament tension and cause the magnetic surface to stretch into the tokamak vessel. Solar flares on the surface of the sun erupt and also reconnect through the process of magnetic reconnection.

After this bubble has been created in NSTX it carries a current of more than 250 thousand amperes, which is 100 times more than the seed current used to initiate the discharge. As a result of this very high current multiplication factor the process is efficient and consumes less than one Joule of stored energy to generate 10 amperes of current. The CHI method has been studied in the smaller Helicity Injected Tokamak (HIT-II) at the University of Washington in which the current multiplication factor was six. NSTX is thirty times larger in volume, and researchers have found the process to be much more efficient on NSTX, indicating that the method scales well to future larger machines.

In a steady-state reactor this initial current would be sustained by injecting high-energy particles. These particles would produce more current if the plasma density is small. For easier control of high-performance plasma, it is necessary that the distribution of the plasma current is preferentially driven near the outer edges of the magnetic configuration. The recent CHI discharges on NSTX have also generated the start-up current with these desired features needed for steady-state operation.

These exciting new results, combined with the capability of CHI to produce a large amount of current at high efficiency in larger machines, bodes well for the application of this new method in future tokamaks and spherical tokamaks. These results are being presented in an invited talk at the 52nd annual meeting of the American Physical Society's Division of Plasma Physics, being held Nov. 8-12 in Chicago.


Story Source:

The above story is based on materials provided by American Physical Society. Note: Materials may be edited for content and length.


Cite This Page:

American Physical Society. "Getting to know the Sun advances fusion research: Coaxial helicity injection could make fusion reactors cheaper." ScienceDaily. ScienceDaily, 9 November 2010. <www.sciencedaily.com/releases/2010/11/101108071912.htm>.
American Physical Society. (2010, November 9). Getting to know the Sun advances fusion research: Coaxial helicity injection could make fusion reactors cheaper. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2010/11/101108071912.htm
American Physical Society. "Getting to know the Sun advances fusion research: Coaxial helicity injection could make fusion reactors cheaper." ScienceDaily. www.sciencedaily.com/releases/2010/11/101108071912.htm (accessed October 20, 2014).

Share This



More Matter & Energy News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gulfstream G500, G600 Unveiling

Gulfstream G500, G600 Unveiling

Flying (Oct. 20, 2014) Watch Gulfstream's public launch of the G500 and G600 at their headquarters in Savannah, Ga., along with a surprise unveiling of the G500, which taxied up under its own power. Video provided by Flying
Powered by NewsLook.com
Japanese Scientists Unveil Floating 3D Projection

Japanese Scientists Unveil Floating 3D Projection

Reuters - Innovations Video Online (Oct. 20, 2014) Scientists in Tokyo have demonstrated what they say is the world's first 3D projection that floats in mid air. A laser that fires a pulse up to a thousand times a second superheats molecules in the air, creating a spark which can be guided to certain points in the air to shape what the human eye perceives as an image. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
What We Know About Microsoft's Rumored Smartwatch

What We Know About Microsoft's Rumored Smartwatch

Newsy (Oct. 20, 2014) Microsoft will reportedly release a smartwatch that works across different mobile platforms, has a two-day battery life and tracks heart rate. 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