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1.媒體來源:


2.完整新聞標題/內文:
【聯合報／By DONALD OSBORNE／陳世欽譯）】
By KENNETH CHANG and WILLIAM J. BROAD

After years of disappointing results , a $5 billion laser complex has now
achieved a step that revives optimism that thermonuclear fusion, the process
that powers the sun, can one day be harnessed for almost limitless energy.

At the National Ignition Facility at the Lawrence Livermore National
Laboratory in California, 192 enormous lasers fire at a small gold cylinder,
vaporizing it. That generates an onslaught of X-rays rushing inward toward a
fuel pellet smaller than a peppercorn, crushing the hydrogen inside into
helium, and releasing a burst of energy — effectively, a miniature hydrogen
bomb.

That, at least, was the concept.

But since the facility began operations in 2009, the last step — the fusion
of hydrogen atoms into helium — did not happen in significant quantity,
until September.

Writing in the journal Nature, scientists working on the project report on
shots in September and November. In both, the hydrogen fusion generated more
energy than had been deposited into the hydrogen. Still, laser-driven fusion
remains far from practical, because only about 1 percent of the laser energy
reached the hydrogen.

“A lot of people are jazzed,” Omar A. Hurricane, the scientist leading the
project, said . “We’re certainly in a lot better position than we were. ”

A longstanding hope is that fusion can become a bountiful, cleaner energy
source than fossil fuels or nuclear fission, which splits uranium atoms and
produces radioactive waste. Planning began two decades ago, both as an energy
experiment and as an aid in the maintenance of nuclear weapons, providing a
way to verify computer simulations without detonating nuclear tests.

But the output of the experiments consistently fell short of what was
predicted, suggesting that the scientists’ understanding of fusion was
incomplete.

Experts say the new results should help give the giant laser more time to
prove its ultimate worth and gain support. It is financed by the United
States Department of Energy, and had a budget this year of about $330 million.

Stephen E. Bodner, a critic of the laser complex and former director of a
similar effort at the Naval Research Laboratory in Washington, said the
project had managed to reinvent itself.

“A lot of people were saying it should be killed off,” he said . “Now, the
general view is that they’re doing much better science. ”

A particularly promising result is that the helium nuclei produced by the
initial fusion burst warmed neighboring hydrogen atoms. Currently only a tiny
speck of hydrogen fuses, and for the laser approach to work, the fusion
reactions would have to propagate through the rest of the hydrogen fuel.

Robert J. Goldston, a professor at Princeton University in New Jersey ,
likened the process to lighting a match and then igniting a stack of lumber.

“They’re close to getting the match lit,” Dr. Goldston said. “Which is a
big step.”

Lasers are not the only approach aimed at harnessing fusion for future power
plants. Scientists have also used doughnut-shaped reactors called tokamaks
that use magnetic fields to contain and compress the hydrogen fuel. In the
late 1990s, the Joint European Torus experiment in England was able to
generate 16 million watts of fusion power for a brief moment, about 70
percent of the way to producing as much power as it consumed.

An international project named ITER is now building a larger tokamak reactor
in France, scheduled to start running in 2020.

中譯





至少概念是如此。

然而這座設施2009年開始運作後，最後的步驟─氫原子融合成氦─在去年九月之前，從未
產生足夠的量。





專家指出，最新結果應該能讓這座巨大雷射有更多時間證明自己的終極價值，從而獲得支
持。這項計畫由美國聯邦能源部出資，今年的預算約3.3億美元。

批評這座雷射設施並曾在華府海軍研究實驗室主持類似計畫的波德納表示，這項計畫已經
重獲新生。

他說：「原先許多人都說這計畫應該放棄。如今普遍的看法卻是他們在科學方面大有進展
。」

尤其大有可為的一個結果是，初步融合產生的氦核使周邊的氫原子溫度升高了。目前，只
有少量的氫會融合，而雷射方法奏效的前提是，融合反應必須透過其他的氫燃料增生。





一項名為國際熱核融合實驗（ITER）的計畫目前正在法國興建另一個更大的托卡馬克反應
裝置，預計2020年開始運作。



3.新聞連結:


http://0rz.tw/NA2vB
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