ARTICLE: Self-Sustaining Fusion

[John Jacobus <crispy_bird@YAHOO.COM>]

I found this article that appeared in the on-line IEEE

SPECCTUM magazine and thought it would be on interest

to some of those on this listserver.



The Article and graphic can be found at

http://www.spectrum.ieee.org/WEBONLY/publicfeature/jan04/0104epow3.html





Self-Sustaining Fusion 



A reactor is on the horizon—but will it always be on

the horizon? 



By William Sweet



Thermonuclear fusion is, in principle, a hugely

attractive energy source. It relies on a fuel,

hydrogen, that abounds everywhere in the world, and on

processes that release no greenhouse gases. In

contrast to nuclear fission, it yields only

short-lived radioactive waste that is relatively

easily handled and cannot be made into raw material

for nuclear weaponry. 



If a fusion reactor could be made to work

economically, the payoff would truly be a Holy Grail.

The rub: enormous amounts of pressure and heat are

required to make fusion happen, and even if the

technical feat of creating self-sustaining fusion

reactions can be accomplished in principle, there

remain the challenges of achieving a net energy gain

and, even tougher, a net economic gain.  







--------------------------------------------------------------------------------

POWER SQUEEZE: In the gourd-shaped toroidal cavity of

the proposed tokamak reactor, a plasma is heated and

compressed by magnetic fields set up by the

surrounding coils to generate self-sustaining fusion

reactions. 

--------------------------------------------------------------------------------



So great are those challenges, in fact, that the

prospect of building a commercially viable reactor has

come to resemble an ever-receding mirage—a promise

that is somehow always just 25-50 years ahead. 



In fusion, hydrogen isotopes are made to combine to

form helium, bringing an enormous energy yield with

the release of neutrons and alpha particles. One way

of doing this, called intertial confinement fusion, is

to train giant lasers on pellets of hydrogen fuel.

That's what's being done at Lawrence Livermore

National Laboratory's National Ignition Facility in

California, mainly to test and evaluate some of the

processes that take place in thermonuclear weapons. 



The favored approach for electricity generation,

dubbed magnetic confinement, is to achieve compression

and heating of the isotopes by means of powerful

fields, usually in toroidal machines. It got its first

big tests at the Joint European Torus, Abingdon, UK,

and at the Princeton Plasma Physics Laboratory in New

Jersey, where reactors momentarily demonstrated

sustained reactions in the mid-1990s. 



The next main event is to be the design and completion

of ITER, the International Thermonuclear Experimental

Reactor, an international collaboration in a US $5

billion plant to generate continuous self-sustaining

reactions in a so-called burning plasma. ITER has

suffered many vicissitudes since its conception more

than a decade ago, including decisions by the U.S.

government to drop out of and then rejoin the group.

The U.S. Department of Energy has now declared ITER

its highest priority among major new facilities and

upgrades, but the project still awaits a final design

and selection of a site. 



No project of this scale gets adopted without a lot of

politics. U.S. President George W. Bush decided to get

back into ITER under considerable pressure from

Britain's leader, Tony Blair, and evidently he backed

a proposed site near Barcelona in return for Spain's

support in the Iraq war. The European Union,

meanwhile, has thrown its support to a site in

southern France, at the Cadarache nuclear complex; the

choice between that site and one in Japan was to have

been made on 20 December in Washington, D.C





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"There's no trick to being a humorist when you have the whole government working for you."

Will Rogers



-- John

John Jacobus, MS

Certified Health Physicist

e-mail:  crispy_bird@yahoo.com



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