"We are creating tomorrow's sun."

How did the human dream of creating the sun begin?
Nuclear fusion, one step closer to commercialization
A new future of energy: the sun trapped in a magnet: the tokamak.

How does the sun shine? People have long wondered about this secret.
Yesterday, today, for decades, centuries, thousands of years, the sun has been shining brightly.
Nuclear fusion began as a search for the source of the sun's inexhaustible energy.
The advent of radioactivity in the late 19th century opened the door to the atom, and the first half of the 20th century was the golden age of nuclear physics and quantum mechanics.
As I gradually learned how nuclei split, I also wanted to know how nuclei come together one by one.
Hydrogen combined to form helium, and the reduced mass was converted into energy, emitting light.
Standing on the shoulders of many scientists, Hans Bethe uncovered the secrets of this starlight.
Many people came together and split the atom to create the atomic bomb.
And then they combined atoms to create a hydrogen bomb.
Now they wanted to light up their homes and factories with the energy of a giant hydrogen bomb.
Soviet scientists have figured out how to trap a tiny sun in a magnet.
The nuclear fusion reactor called 'Tokamak' was born.


Many demons lived in the plasma of the tokamak.
He wanted to freely use the immense energy of the sun, but the demons did not easily open the door.
Among these, instability and turbulence were particularly difficult to tame.
But now it's almost in my hands.
The efforts and challenges of the International Thermonuclear Reactor (ITER), which is currently under construction, research institutes around the world, and young startups that have been competing to produce results in recent years are shining.
According to the 2023 survey data (https://www.fusionindustryassociation.org/fusion-industry-reports/) released by the Fusion Industry Association, more than 7 trillion won is being invested in these companies worldwide, going beyond the level of vague interest.
It is expected that better-than-expected results will be achieved soon.
South Korea, which began nuclear fusion research less than fifty years ago, has built KSTAR, a superconducting nuclear fusion reactor, through skilled researchers and steady investment over the past twenty years.
Now, KSTAR is producing a series of surprising experimental results that are attracting worldwide attention.
This book thoroughly examines the history and future of nuclear fusion research in Korea.

In Part 1 of this book, we explore the reasons why the sun shines so brightly with Hans Bethe and introduce the principles of nuclear fusion.
Next, the story of the Manhattan Project and the development of the hydrogen bomb unfolds through Enrico Fermi.
Part 2 shows the process of creating and completing a "tokamak," a device for nuclear fusion, through a fictional project called "The Furnace of Thought," set in a secret Soviet research institute that actually existed.
Here, readers will not simply be observers of the project, but will be involved as actual researchers, solving problems faced by contemporary Soviet scientists.
Part 3 will examine the development of tokamak by visiting major nuclear fusion research institutes around the world, including the Max Planck Institute in Germany and ITER.
In Part 4, we will examine the process of generating electricity in a tokamak and the many challenges remaining in commercializing nuclear fusion energy.
Part 5 will look back on the history of nuclear fusion research in Korea, focusing on KSTAR.

When faced with such problems, an engineering approach asking, "How can we solve the problem?" was needed, rather than a scientist's theory asking, "Why is that?" or a mathematician's calculation.
Or maybe it's the artist's sixth sense.
“How about Natan Yavlinsky, who has extensive experience in power plant design and construction at the Moscow Institute of Power Technology?”
Artimovich entrusted Yavlinsky with the construction of the device.
Yavlinsky began designing the device in close collaboration with us.
Golovin and Yavlinsky oriented the design so that the magnetic field strength along the axis of the torus was greater than that along the circumference.
Thus, the first tokamak device was completed in 1958.
The name was T-1.
--- p.218

News of ZETA's existence and the detection of neutrons began to leak out to the press little by little.
An official response was needed.
On January 25, 1958, Sonnerman published the results of his ZETA experiment in Nature.
The detected neutrons were approached with extreme caution. The ZETA experiment's results received widespread media attention, and Cockcroft, who led Howell, held a press conference.
However, during the press conference, he was caught up in reporters' leading questions and ended up making the careless remark that he was certain that the neutrons detected at ZETA were derived from nuclear fusion.
This news soon reached us.
We, including Artimovich, questioned the results of ZETA.
This was because it was not easy to cause a nuclear fusion reaction at 50 million degrees.
The American speaker also had the same opinion.
(……) Unfortunately, support for ZETA was discontinued as a result of this incident.
--- p.221~222

The IAEA was established on July 29, 1957, and the following year, the Second United Nations International Conference on the Peaceful Uses of Atomic Energy was held in Geneva, Switzerland, from September 1 to 13, 1958.
Nuclear fusion was adopted as one of the conference's main topics, shortly after the ZETA results were published in Nature.
(……) Artimovich gave the presentation as a representative of the Academy of Sciences of the USSR.
(……) Secondly, the torus device was introduced.
They theoretically showed that the axial magnetic field of the torus must be larger than the circumferential magnetic field to obtain a stable plasma, and added that they verified this using an 'Experimental Arrangement' made of 0.2 millimeter thick stainless steel.
The average torus diameter of this device was 1.25 meters, and the cross-sectional diameter of the torus was 0.5 meters.
The plasma current was 400,000 amperes and the axial magnetic field was 1.2 Tesla.
The temperature of the electron was still only 150,000 to 250,000 degrees.
Arzimovich attributed the low temperature to the instability of the plasma and impurities from the walls confining the plasma.
This 'experimental device' was the tokamak.
--- p.224

Artimovich, who still did not fully believe in the tokamak, introduced it as an “experimental device” without mentioning the name “tokamak” at the conference.
The Soviet Union was concentrating on promoting Sputnik, the world's first artificial satellite, which was the pride of the Soviet Union at the time, rather than promoting the tokamak in Switzerland.
Princeton's Spitzer also paid little attention to the results from the tokamak, which had no device to measure the plasma temperature.
At the time, no one realized that the Soviet 'experimental device' would later change the landscape of nuclear fusion.
--- p.228

The second IAEA Fusion Conference was held in Culham, England, in 1965, and four years later, in 1968, the third IAEA Fusion Conference was hosted by the Soviet Union, in Novosibirsk, Siberia, deep behind the Iron Curtain.
Novosibirsk is the third largest city in Russia and the largest in Siberia by population.
(……) At the conference, Director Archimovich presented the results we had achieved so far.
“In our tokamak, we achieved an electron temperature of 10 million degrees and an energy confinement time of 0.01 seconds.
“It delivers performance that is two to ten times better than previously known devices.”
Artimovich's announcement immediately caused a huge stir.
At first, people did not believe this surprising result.
--- p.244

Throughout the conference, countless questions were asked of Artimovich and us, and endless debate ensued.
Seeing it for yourself is hard to believe, so Archimovich approached Sebastian Peace, director of the Culham Centre for Fusion Energy in the UK, with an intriguing proposal.
The British were asked to verify the results of the tokamak.
At that time, Britain had been pouring all its efforts into developing new diagnostic devices since ZETA, and one of them was the completion of a method to accurately measure the temperature of electrons with a laser using Thomson scattering.
(……) In December 1968, at the height of the Cold War, British gentlemen boarded a Pakistan International Airlines flight bound for Moscow carrying five tons of equipment.
The so-called 'Culham Five' were scheduled to stay and conduct experiments at the Kurchatov Institute, the headquarters of Soviet nuclear bomb research.
--- p.245

The T-3 device, equipped with a laser scatterer imported from the UK, conducted a total of 88 plasma experiments until August of the following year.
After several failed attempts, the device was able to measure the plasma temperature of the tokamak.
The measured value was 10 million degrees.
It was the same result that Artimovich had declared a year earlier.
It was solid evidence that no one could doubt.
In 1969, the year humans first set foot on the moon and the Concorde passenger plane achieved supersonic flight, news of the T-3, which broke through the Iron Curtain and spread to the world, changed the course of nuclear fusion research.
--- p.246

When the Culham Five returned to England, the Culham Laboratory's stellarator device, proto-CLEO, attempted to convert into a tokamak.
Princeton, the cradle of the stellarator, was no exception.
Nuclear fusion devices around the world are undergoing a major transformation into tokamak reactors.
It was the beginning of the so-called 'Tokamak Fever', the 'Soviet invasion', and the birth of the 'Tokamakists'.
Since then, research has been conducted 'of the tokamak, by the tokamak, for the tokamak' all over the world.
And the tokamak was later adopted as the method for the International Thermonuclear Experimental Reactor (ITER), and developed into a first-generation method for commercializing nuclear fusion.
--- p.249

This was a huge blow to the stellarator.
At the time, the Wendelstein II-A stellarator at the Max Planck Institute for Plasma Physics in Germany was showing, for the first time ever, results in plasma confinement that were identical to theoretically predicted values.
All existing devices had experimental results that were far below theoretical predictions.
Scientists called it the 'Munich Riddle'.
(……) When talking about history, the hypothesis of ‘what if’ doesn’t have much meaning, but still, if stellarator research had continued, ITER might have been replaced by a stellarator method rather than a tokamak.
--- p.212

Professor Karl Rachner said with a smile.
“Fritz, you’re talking about balloons again.
In short, you want to confine the plasma inside the tokamak with a magnetic field, but you want to keep the pressure as high as possible and keep it stable for a long time, right?”
It was Professor Lackner, head of the Theory Department at the Max Planck Institute for Plasma Physics.
As he said, the balloon represented the tokamak's magnetic field, and the air inside the balloon represented plasma.
--- p.259

IAEA Fusion Conference held in Baltimore, USA, September 1982.
Professor Wagner took the podium representing the Max Planck Institute for Plasma Physics.
He makes a startling declaration, much like Artsimovich did in 1968, that caused a stir in nuclear fusion research around the world.
“We have discovered a new plasma state in the tokamak where plasma transport is greatly reduced and confinement performance is dramatically improved.
This plasma has nearly twice the pressure of conventional plasma.
“The energy retention time is more than twice as long.”
It was a historic moment, declaring the discovery of 'H-mode'.
These were results obtained from the Asdex tokamak device at the Max Planck Institute for Plasma Physics, which began operation in 1980.
Professor Wagner called the existing plasma state 'L-mode (low confinement mode)', or low confinement mode, and named the new plasma state 'H-mode (high confinement mode)', or high confinement mode.
Good energy retention means that hot water in a thermos can stay hot for longer than if it were put in a regular water bottle.
Normally, you change the container to increase insulation, but this time it was different.
By simply changing the experimental conditions in the same tokamak device, a plasma with better thermal insulation properties was obtained.
The discovery of the H-mode shook the fusion world to its core.
All tokamak devices around the world are working hard to implement H-mode.
H-mode was soon reproduced in the US PDX and Doublet III, the European Union JET, and Japan's JT-60.
(……) Professor Wagner, who was leading the Asdex tokamak, moved to the position of head of the Wendelstein 7-AS, a stellarator device, in 1989 and continued his stellarator research.
(……) In 1992, the H-mode was also discovered in Wendelstein 7-AS.
This proved that the H-mode is a universal phenomenon in torus-shaped magnetic field nuclear fusion devices, and thus the H-mode became a kind of 'rite of passage' that indicates that the tokamak device is functioning properly.
--- p.263~264

In 1971, the European Community (EC) launched a project to develop a large-scale nuclear fusion device that would represent Europe.
First, under the leadership of Frenchman Paul-Henri Revue, the design began in 1973, and the plan was completed in 1975, proposing the construction of the Joint European Torus (JET), which was the world's largest tokamak device at the time.
(……) When the JET project was proposed, a competition began among European countries to host it.
Five sites were nominated: Culham in England, Garching in Germany, Cadarache in France, Ispra in Italy and Moll in Belgium.
Soon, the five candidates were narrowed down to Culham, home to the UK's Atomic Energy Laboratory, and Garching, Germany, home to the Max Planck Institute for Plasma Physics, and a cutthroat competition unfolded between the two countries.
--- p.230

October 13, 1977, Mallorca, Spain, in the middle of the Mediterranean Sea.
A terrible incident occurred in one of Germany's favorite vacation spots.
Lufthansa Flight 181, en route from Palma, the capital of Mallorca, to Frankfurt, was hijacked over Marseille just 30 minutes after takeoff.
(……) Just after midnight on October 18, the West German government mobilized the Federal Police's Border Guard Unit 9 (GSG 9) to retake Landshut. GSG 9 was a special counter-terrorism unit created in the wake of the brutal murder of 11 Israeli Olympic participants taken hostage by Black September during the 1972 Munich Olympics.
(……) They successfully rescued 86 hostages within 5 days of the incident by killing 3 kidnappers and capturing 1.
At the time, the British government dispatched members of the SAS, the first modern counter-terrorism unit, and even provided special weapons, which greatly helped Germany successfully suppress terrorism.
--- p.287

In 1977, after many twists and turns, it was decided that JET would be built in Culham, near Oxford, England.
A total budget of UC 100 million was invested in JET for construction costs.
(……) 100 million UC is equivalent to approximately 500 billion won.
As a result, the jet incident ended up giving JET to Britain.
--- p.287

As giant tokamak devices such as the European Union's JET, the United States' TFTR, the Soviet Union's T-15, and Japan's JT-60 began to advance toward commercializing nuclear fusion, nuclear fusion research entered a new era and entered into fierce competition among countries.
--- p.294

The European Union's JET, the only fusion reactor in the world to use deuterium and tritium as nuclear fusion fuel, and the TFTR at the Princeton Plasma Physics Laboratory in the United States were locked in a fierce competition where they could not yield an inch.
The question was who would achieve Q = 1 first.
(……) In 1988, at the European Physical Society meeting in Yugoslavia (now Croatia), a bet was made between two scientists representing the United States and Europe. Robert Goldstone of TFTR and Jean Giacchino of JET made a bet as to which of their teams would be the first to sustain 10 megawatts of fusion power for more than a second. If TFTR won, Giacchino would treat the entire TFTR team to a French dinner, and if JET won, Goldstone would send McDonald's hamburgers to the entire JET team.
--- p.296

However, the decisive factor was the shape of the plasma cross-section. JET was able to significantly improve performance by installing a diverter to prevent the plasma from being contaminated with impurities.
In addition, referring to the research of Artsimovich and Shapranov, the stability of the plasma was greatly improved by making the cross-sectional shape of the plasma closer to the shape of the letter D rather than a circle.
TFTR, on the other hand, was a circular plasma without a diverter.
(……) In 1997, JET injected 24 megawatts into the plasma and obtained 16 megawatts of fusion power, with a fusion energy amplification factor of 0.67.
Although it was a short time of just over 0.1 seconds in H-mode without boundary instability, it was a world record. TFTR made various attempts to surpass this record, but ultimately failed to overcome this obstacle.
Defeated in the war, TFTR came to a grand close in 1997 after 15 years of operation.
Instead, Princeton took on a new challenge by building the National Spherical Torus Experiment (NSTX), a spherical tokamak device with a smaller ratio of major to minor radii than a typical tokamak, following in the footsteps of TFTR.

--- p.297