Featured Research

from universities, journals, and other organizations

Major fusion advance: Breakthrough could help reduce heating of plasma container walls

Date:
November 16, 2010
Source:
American Physical Society
Summary:
Researchers have taken steps toward practical fusion energy through better understanding of the physics that governs the interaction between plasmas and the material walls of the vessels that contain them.

Heat escaping a fusion plasma tends to focus into narrow "footprints."
Credit: Image courtesy of American Physical Society

Researchers at the Massachusetts Institute of Technology have taken steps toward practical fusion energy through better understanding of the physics that governs the interaction between plasmas and the material walls of the vessels that contain them.

The best developed approach for practical fusion energy employs magnetic bottles to hold and isolate extremely hot plasmas inside a vacuum vessel. Using magnetic fields for thermal insulation has proven quite effective, allowing plasma temperatures in excess of 100 million C to be attained -- conditions under which the nuclei fuse and release energy. The tokamak device, a torus or donut-shaped magnetic bottle, has been found to perform particularly well and is the basis for ITER, a full-scale international fusion experiment presently under construction in France with U.S. participation. Projections from current experiments to ITER, and beyond to energy producing reactors, presents a number of scientific and technical challenges. Prominent among these is handling the very large heat loads which occur at the interface between the plasma and the materials from which the reactor is constructed.

Magnetic insulation comes with a catch. Heat that leaks out of the bottle is focused into narrow channels as it streams along magnetic field lines in adjoining boundary layers. This produces narrow footprints on wall surfaces. The smaller the footprint, the more intense the heat flux becomes. In fact, the intensity can easily exceed the power handling ability of present technologies. Even worse, certain naturally occurring plasma oscillations can create transient heat loads which are larger still. Recent experiments on the Alcator C-Mod tokamak are aimed at understanding and overcoming this challenge by reducing the steady-state power conducted to the wall, by characterizing the physics which sets the area over which this power is distributed, and by investigating a confinement regime that eliminates transient heat loads.

One set of recent experiments in Alcator C-Mod used ultra-violet radiation from injected impurities to decrease power reaching the divertor, a portion of the wall with the highest heat flux footprint. These results are significant for ITER as well as future fusion reactors that will provide commercial electricity, and show that redistributing the exhaust power by impurity radiation is a viable option.

Different experiments, aimed at understanding the physics that sets the heat-flux footprint size, have discovered its width is independent of the magnetic field line length. This behavior appears counter-intuitive at first, but is part of a growing body of evidence that self-regulatory heat transport mechanisms are at play, which tend to clamp the width of the heat flux profiles at a critical scale-length value.

Another aspect of the plasma-wall challenge is the elimination of transient heat loads, which arise from a relaxation oscillation produced spontaneously in many high performance plasmas. These oscillations help expel unwanted impurities that can contaminate the plasma, but they can also lead to unacceptably high power loads. Ongoing experiments are studying a confinement regime that simultaneously achieves good energy confinement without accumulation of impurities and without the oscillations.

These new findings are being presented in three invited talks 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. "Major fusion advance: Breakthrough could help reduce heating of plasma container walls." ScienceDaily. ScienceDaily, 16 November 2010. <www.sciencedaily.com/releases/2010/11/101108071910.htm>.
American Physical Society. (2010, November 16). Major fusion advance: Breakthrough could help reduce heating of plasma container walls. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2010/11/101108071910.htm
American Physical Society. "Major fusion advance: Breakthrough could help reduce heating of plasma container walls." ScienceDaily. www.sciencedaily.com/releases/2010/11/101108071910.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) — AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Shipping Crates Get New 'lease' On Life

Shipping Crates Get New 'lease' On Life

Reuters - Business Video Online (July 25, 2014) — Shipping containers have been piling up as America imports more than it exports. Some university students in Washington D.C. are set to get a first-hand lesson in recycling. Their housing is being built using refashioned shipping containers. Lily Jamali reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) — Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) — TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
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:
from the past week

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