世界上最大的磁场圆环装置剛剛打破了核聚變能的記錄

Recently Yahoo News on-lines reported the following:

The World's Largest Tokamak Just Crushed the Record for Nuclear Fusion Energy

Popular Mechanics - Caroline Delbert

Wed, February 16, 2022, 9:30 AM

England's Joint European Torus (JET) tokamak has produced 59 megajoules of energy for five seconds, breaking the previous nuclear fusion record from 1997.

JET is a training ground for the much larger, more ambitious ITER reactor.

The 59-megajoule record has a power ratio of Q=.33, with an industry goal of Q=1.

The Joint European Torus (JET) experiment housed in England has set a new record for the power generated by a burst of unfathomably hot plasma. The circular tokamak reactor, which looks like a donut, reached 59 megajoules of energy—a new high for a family of reactors that require an enormous amount of energy to get up to operational speed.

JET is part of the Culham Centre for Fusion Energy just outside Oxford, England. The Centre is the national laboratory for nuclear fusion research in the United Kingdom, previously known as "UKAEA Culham" after the U.K. Atomic Energy Authority. It's awkward that the Joint "European" Torus is no longer a part of Europe, but that's partly because the project dates back 40 years to the early 1980s.

For about ten years, the original JET tokamak operated with the same goal that fusion projects have today: to generate enough energy to be productive against the fusion reactor's enormous energy cost for operation. For decades, the reactor iterated, meaning it was adjusted and refined over time to continue trying to reach its goals. Then, in 2009, it shut down completely for more of an overhaul. Today's JET is almost unrecognizable when you compare it to what the 1980s researchers built.

JET is a tokamak, which is basically a donut- or spherical-shaped tunnel where hydrogen isotopes are contained by a powerful magnetic field and then superheated until they're far hotter than the sun. It's at these high temperatures that the atoms' nuclei smash together, literally nuclear fusion. The reaction generates enormous energy relative to the amount of fuel required.

Over time, JET has learned lessons from the International Thermonuclear Experimental Reactor (ITER), a project that started later, but had massive funding and truly global participation. Results from ITER experiments helped JET to further tailor its goals, proving especially helpful while revamping JET between 2009 and 2011. Now, the two are working together to design experiments at JET that will help researchers at ITER make better decisions.

One way JET has led the way globally is by using fuel made of deuterium and tritium, names for two isotopes of hydrogen. Protium is the most common form of hydrogen, consisting of just one proton. Stable deuterium has a proton as well as a neutron (its name meaning two, like "deuce"), while radioactive tritium has one proton and two neutrons. The fuel sources are far better than protium, but the extra neutrons are sprayed around and can cause problems. To counter this, JET now has a special tungsten and beryllium shielding that will also be part of ITER.

All this background leads us to the exciting new record. In December, JET created an astonishing 59 megajoules of energy and sustained that for five full seconds—the longest possible amount of time before the reactor overheats. With nuclear fusion, the goal is to reach an advantageous power ratio of Q=1, where Q is the amount of energy generated divided by the amount of energy the reactor requires to operate. That means each facility's Q value is made from different parts: 59 megajoules might mean a Q of 20 at some tiny fusion reactor.

At JET, 59 megajoules is .33Q, which is still a step in the right direction, scientists say. They insist that at the massive ITER, which will be the largest fusion reactor in the world by far, the same processes that led to the record at JET will mean ITER is reaching productive fusion, or a Q greater than 1. Time will tell, because ITER isn't set to power up its first plasma run for years to come.

Translation

英國的聯合歐洲圓環 (JET) 的磁场圆环装置裝置在 5 秒內產生了 59 兆焦耳的能量，打破了自 1997 年以來的核聚變記錄。

JET 是更大、更雄心勃勃的 ITER 反應堆的訓練場。

59 兆焦耳記錄的功率比為 Q=0.33，行業目標為 Q=1。

位於英格蘭的聯合歐洲環面 (JET) 實驗創造了由熱等離子體爆發所產生大不可測的能量的新記錄。看起來像一個甜甜圈的圓形磁场圆环反應堆達到了 59 兆焦耳的能量 - 對於需要大能量才能達到運行速度的反應堆系來說，這是一個新高。

JET 是位於英國牛津郊外的 Culham 聚變能源中心的一部分。該中心是英國核聚變研究的國家實驗室，前身為英國原子能局之後的 “UKAEA Culham” 。令人尷尬的是，聯合 “歐洲” 圓環不再是歐洲的一部分，部分原因是該項目可以追溯 40 年到 1980 年代初。

大約十年來，最初的 JET 磁场圆环装置的運行目標與今天的聚變項目相同：產生足夠的能量來抵消聚變反應堆運行所需的巨大能源成本。幾十年來，反應堆不斷迭代，這意味著它會隨著時間的推移進行調整和完善，以繼續努力實現其目標。然後，在 2009 年，它完全關閉以進行更多的檢修。今天的 JET 與 1980 年代研究人員建造的相比幾乎無法認出。

JET 是一個磁场圆环装置，它基本上是一個甜甜圈或球形隧道，其中氫同位素被強大的磁場所包圍，然後加進超高熱，直到它們比太陽熱得多。正是在如此高的溫度下，原子的原子核相互碰撞，實際上是核聚變。由反應所產生巨大能量是相對於所需的燃料量。

隨著時間的推移，JET 從較後期開始的國際熱核實驗反應堆 (ITER) 中吸取了教訓，該項目擁有大量資金和真正的全球參與。 ITER 實驗的結果幫助 JET 進一步調整其目標，證明对JET在 2009 年至 2011 年期間進行的改造特別有用。現在，兩機構正在合作設計 JET 的實驗，這將幫助 ITER 的研究人員做出更好的決策。

JET 引領全球的一種方式是使用由氘和氚製成的燃料，這兩種同位素是氫的兩種同位素。氕是最常見的一種氫，僅由一個質子組成。穩定的氘有一個質子和一個中子（它的名字意思是兩個，如“deuce”），而放射性氚有一個質子和兩個中子。燃料源比氕好得多，但多出的中子會四處噴濺，可能會引起問題。為了解決這個問題，JET 現在有一個特殊的鎢和鈹屏蔽層，它也將成為 ITER 的一部分。

所有這些背景都將我們引向令人興奮的新紀錄。 在12 月，JET 創造了驚人的 59 兆焦耳能量，並持續了整整 5 秒 - 這是反應堆過熱之前可能的最長時間。對於核聚變，目標是達到 Q=1 的有利功率比，其中 Q 是產生的能量除以反應堆運行所需的能量。這意味著每個設施的 Q 值由不同的部分組成：59 兆焦耳可能意味著某個小型聚變反應堆的 Q 值為 20。

科學家們說，在 JET，59 兆焦耳是 0.33Q，這仍然是朝著正確方向邁出的一步。他們堅持認為，在大型 ITER 上，這將是迄今為止世界上最大的聚變反應堆，導致 JET 創紀錄的相同過程將意味著 ITER 正在達到生產性聚變，或者 Q 大於 1。這需要時間去證明，因為 ITER 不會在未來幾年內啟動其首次等離子運行。

            So, at the massive ITER, which will be the largest fusion reactor in the world by far, the same processes that led to the record at JET will mean ITER is reaching productive fusion, or with a Q greater than one. The next step is to find out how to convert the energy produced into a usable form, for example electricity.

Note:

1. A tokamak is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. As of 2021, it is the leading candidate for a practical fusion reactor. By the mid-1970s, dozens of tokamaks were in use around the world. As of 2020, JET (the Joint European Torus) remains the record holder for fusion output, reaching 16 MW of output for 24 MW of input heating power. (https://en.wikipedia.org/wiki/Tokamak)