How close are we to powering the world with nuclear fusion? - George Zaidan

譯者: Mina Huang 審譯者: Zoe Walmsley

In the time it takes to snap your fingers,

在你彈指的瞬間裡

the Sun releases enough energy to power our entire civilization for 4,500 years.

太陽釋放出的能量相當 整個人類文明 4500 年所需。

So naturally, scientists and engineers have been working to build

自然而然地，科學家和工程師一直努力

想在地球上打造一顆小太陽 連上我們的電網。

a miniature star here on Earth... to plug into our power grid.

And the thing is, we already kind of have.

但事實上，我們早已經有了，

It just doesn’t look like a tiny star floating in a lab.

只是它看起來不像是 漂浮在實驗室中的小太陽，

The stars are made of an almost incomprehensible number of particles,

而是由無法計數的粒子所組成，

which gravity compresses into a super dense core.

它們被重力壓縮成一個高密度原子核。

This core is hot and dense enough to force atomic nuclei together,

這個核子的熱度及密度 足以讓原子核互相結合，

forming larger, heavier nuclei in a process known as fusion.

透過所謂核融合的過程 形成更大、更重的核子。

The reverse process, where one atom splits into two, is called fission.

另有一個所謂核分裂的過程， 則是將一個原子分裂成兩個。

In both processes, the mass of the end products is slightly less

這兩個不同的過程最終產出的質量

都略少於一開始時的原子的質量。

than the mass of the initial atoms.

But that lost mass doesn’t disappear—

但是，少掉的部分並非消失，

it’s converted to energy according to Einstein’s famous equation.

而是如愛因斯坦著名的方程式 所說的轉換為能量。

And since c² is such a massive number,

而且 c² 是如此龐大的數字，

both fission and fusion generate a lot of energy.

無論是核分裂還是核融合 都會產生巨大能量。

Fusion in our Sun mostly produces helium nuclei.

太陽中的核融合主要製造出氦原子核。

In the most common pathway, two protons fuse to form a deuterium nucleus,

在最常見的路徑中， 兩個質子融合成一個氘-2 核，

which then fuses with another proton to form a helium-3 nucleus,

然後與另一個質子合併 形成一個氦-3 核，

which then fuses with another helium-3 nucleus to form a helium-4 nucleus.

這個氦-3 核再與另一個氦-3 核 合併形成一個氦-4 核。

But there’s a catch— that first step is incredibly rare.

但是有一個問題， 第一個步驟的機率很低。

Only 1 in 100 septillion collisions between protons

平均每 100 秭次的質子碰撞

results in a deuterium nucleus.

只有一次會形成氘-2 核。

In the Sun this isn’t a problem because there are so many protons

但在太陽內部的質子多到 這問題不是問題，

that even a reaction this rare happens all the time.

即使反應機率如此低還是持續發生。

But on Earth, researchers rely on a more easily reproducible reaction,

但地球上的研究人員就得仰賴 更容易複製反應的方式，

where a deuterium nucleus fuses with a tritium nucleus

讓一個氘-2 核與一個氚-3 核融合，

to form a helium-4 nucleus and a neutron.

形成一個氦-4 核和一個中子。

We’ve actually been doing reactions like this one inside particle accelerators

自 1930 年代以來，我們一直用 粒子加速器進行同樣的核反應，

since the 1930s.

But these accelerators are not designed to harness the energy this reaction releases.

但這些加速器一開始的設計 並不是為了核反應產生的動力，

Rather, they’re used to generate neutrons

而是用於產生中子，

for a variety of scientific and military purposes.

運用於科學和軍事的目的。

Whereas if we want to use fusion to produce limitless energy,

如果我們想使用核融合 來產生無限的動力，

we’d need a device that can harness the energy released,

我們需要一個裝置去捕捉 過程中釋放的能量，

channel enough of that energy back into the device to keep the reaction going,

先將足夠的能量送回裝置中 去維持核反應的進行，

and then send the rest out to our power grid.

剩下的則輸送到我們的電網去。

And for that job, we need a nuclear fusion reactor.

而這個工作需要一個核融合反應器。

Like a particle accelerator, a reactor would generate helium nuclei and neutrons.

類似粒子加速器， 反應器會產生氦原子核和中子。

But that reaction would happen in a superhot core

而那反應發生在超熱的核心中，

and the resulting neutrons would shoot outward

將產生的中子向外發射

to heat up a layer of lithium metal.

加熱一層鋰金屬。

That heat would then boil water,

那個熱量再讓水沸騰，

generating steam to run turbines and produce electricity.

產生蒸汽去運轉渦輪機， 進而產生電力。

Meanwhile, the helium nuclei would stay in the core

同時，氦原子核會繼續留在核心

and slam into other nuclei to keep the reaction going—

與其他核子碰撞，讓核反應繼續進行，

and the electricity flowing.

讓電力源源不絕。

This tech has many practical challenges,

這項技術的實際運作有許多挑戰，

including how to confine a swirling mass of million-degree matter.

包括將百萬度高溫、迴旋的質量 侷限在一定空間內。

But the biggest hurdle is achieving what's called ignition.

但最大的障礙是達到起燃的條件。

An energy technology is only commercially viable

任何能源技術要做到商轉發電

if it puts out more energy than it uses.

只有在產能扣除本身所需還有剩餘時。

And a fusion reactor needs a lot of energy to get the core hot enough

而核融合反應器需要大量能量

加熱核心去促成融合作用。

for fusion to occur.

So there’s a tipping point:

因此有個臨界點：

a moment when the fuel is hot enough to start the reaction

當燃料達到能啟動核反應的能量，

and release more energy than is needed to reach and maintain that temperature.

除了供應自身所需 還能將溫度維持在啟動反應的標準，

This is ignition.

這就是起燃條件。

Stars reach ignition under the force of huge amounts of gravity,

太陽靠著極大的重力達到起燃點，

but this approach is impossible on Earth

但這在地球上是做不到的，

since you’d need thousands of times the mass of, well, the entire Earth.

因為所需的質量相當於 整個地球的數千倍。

So researchers typically rely on vast arrays of lasers,

因此，研究人員通常 仰賴許多雷射的集聚光束，

or methods that combine magnets with high energy particles

或結合磁流體動力與高能粒子的方法，

or electromagnetic waves similar to those in your microwave oven.

甚至是類似家中微波爐產生的電磁波。

In 2022, scientists at the US National Ignition Facility

2022 年，美國 國家點火設施的科學家

demonstrated ignition for the first time ever,

首次示範了核聚變點火，

using 192 lasers to heat deuterium and tritium to 100 million degrees.

利用 192 道雷射將氘-2 核 與氚-3 核加熱到一億度。

While this was a huge step forward,

雖然向前跨了一大步，

we’re still a ways off from a self-sustaining, long-running reactor

但距離一個能自我供給、長期運作，

that produces more energy than it uses.

產能多過所需的反應器還有點距離。

But once operational, these relatively small reactors could power a city

但一旦開始運作， 這些規模相對較小的反應器

of a million people for a year with just two pickup trucks of fuel.

只需要兩輛皮卡的燃料， 就能提供一個百萬居民城市一年所需。

Today, you’d have to burn roughly 3 million tons of coal

現在，我們得燃燒約三百萬噸的煤

to produce that much energy.

才能產生這麼多能源。

That is the promise of fusion:

這正是核融合的承諾：

limitless, on-demand energy with almost no emissions.

一個無限的、隨時需要就有的 零碳排的乾淨能源。

True star power, right here on Earth.

一顆在地球上的小太陽。