THENEWYORKER,OCTOBER11, 2021 23
ley told me. “Pretty close to the maxi-
mum amount you could spend in order
to never get there.”
“
T
o be honest, I was feeling pretty
despondent,” Dennis Whyte, the
fifty-seven-year-old director of the
Plasma Science and Fusion Center, at
M.I.T., said. “And I was seeing that de-
spondency in the faces of my students,
too.” It was 2013, and M.I.T.’s experimen-
tal fusion device had lost its Department
of Energy funding, for no clearly stated
reason. The field of nuclear fusion, as a
whole, was still moving forward, but ag-
onizingly slowly. iter, an enormous fu-
sion device being built in southern France,
in an international collaboration, was pro-
gressing—the schedule is for ITER to
demonstrate net fusion energy in 2035,
and the majority of plasma physicists
have high confidence that it will work—
but Whyte knew that it wasn’t going to
deliver affordable energy to the public in
his lifetime, and maybe not in his students’
lifetimes, either. “ITER is scientifically in-
teresting. But it’s not economically inter-
esting,” Whyte said. “I almost retired.”
Whyte is a gentle giant from Sas-
katchewan, Canada. “If you’ve ever been
to the middle of nowhere, that’s where
I grew up,” he told me. His family were
farmers and electricians. By the time he
was in the fifth grade, he knew he wanted
to be a scientist, and in the eleventh
grade he wrote a term paper on that wild
idea which often appeared in science
fiction—near-boundless energy gener-
ated by the fusing of two atoms, as hap-
pens in stars. “I remember getting that
paper back, and my teacher saying, ‘Great
job, but it’s too complicated.’” Wh y t e
went on to major in engineering and
physics at the University of Saskatche-
wan; for his Ph.D., he attended a new
plasma-physics program at the Univer-
sity of Quebec, where he worked in
a government-funded fusion lab. “I
thought, Great: I’ll learn French and get
to work on a tokamak,” he said, refer-
ring to the large doughnut-shaped ma-
chine whose design is commonly used
for fusion devices. Later, Whyte took a
job at a lab in San Diego. He intended
to return home eventually, but in 1997
Canada cancelled its fusion program. “I
was stranded in the U.S.,” he said.
At M.I.T., Whyte teaches an engi-
neering-design class for graduate stu-
dents which he organizes each year around
a different practical problem in fusion.
“I’ve always wanted to expose my stu-
dents not only to the science questions
but also to the technology questions,” he
said. In 2008, he asked his students to
design a device that would pump helium
but not hydrogen—in most approaches
to fusion, hydrogen is the fuel, and he-
lium is, in effect, the ash. “Helium is one
of the hardest things to pump in the pe-
riodic table, because it’s so inert,” Whyte
said. The class came up with several very
clever ideas. None of them was successful.
“We’re still working on that one,” he said.
The next year, something happened
that Whyte credits with restoring his
interest in fusion. “I had passed my col-
league Leslie in the hall, and he was
holding a bundle of what looked like
the spoolings of a cassette tape,” he said.
It was a relatively new material: ribbons
of high-temperature superconductor.
Superconductors are materials that offer
little to no resistance to the flow of elec-
tricity; for this reason, they make ide-
ally efficient electromagnets, and mag-
nets are the key component in tokamaks.
A high-temperature superconductor—
well, it opened up new possibilities, in
the way that the vulcanization of rub-
ber opened up possibilities in the mid-
nineteenth century. The superconduc-
tor material that Whyte’s colleague was
holding could in theory make a much
more effective magnet than had ever
existed, resulting in a significantly smaller
and cheaper fusion device. “Every time
you double a magnetic field, the volume
of the plasma required to produce the
same amount of power goes down by a
factor of sixteen,” Whyte explained. Fu-
sion happens when a contained plasma
is heated to more than a hundred mil-
lion degrees. Whyte asked his class to
use this new material to design a com-
pact fusion power plant of at least five
hundred megawatts, enough to power
a small city: “I was not sure what we
would find with H.T.S., but I knew it
would be innovative.”
The physicists Bob Mumgaard, Dan
Brunner, and Zach Hartwig were in
that class. The power plant that they
came up with was in most respects fa-
miliar. At its center would be a dough-
nut-shaped tokamak, not unlike the type
that Whyte had worked with as a grad-
uate student. They named their design
Vulcan. In the next iteration of the class,
those ideas evolved into a design called
ARC, for “affordable, robust, and com-
pact.” (This also happens to be the name
of the personal fusion device of the bil-
lionaire industrialist Tony Stark, in the
“Iron Man” movies.) ARC would use an
ordinary salt to translate its heat onto
an electrical grid. It would be modular,
for easy maintenance. It would not be
able to recycle its own fuel. It was a
“good enough” machine. But the use of
H.T.S. magnets made it about the size
of a conventional power plant—a tenth
the size of ITER.
Physicists from both classes later
formed a group that modified the arc
design. The new model was two-thirds
the size and intended to be ready as soon
as possible—SPARC. SPARC would be the
prototype that demonstrated the con-
cept; ARC would be a long-lasting power
plant capable of delivering affordable
energy to the grid.
There were real reasons for skepti-
cism. H.T.S. is fragile—it remained to
be seen if it could even be made into a
hardy magnet, and, if it could, how well
that magnet would endure bombard-
ment by charged particles. Plus, H.T.S.
was not yet commercially available at
sufficient scale and performance. “But
those were engineering barriers, not sci-
entific barriers,” Whyte said. “That class
really changed my mind about where
we were in fusion.”
Fusion scientists often speak of
waiting for a “Kitty Hawk moment,”
though they argue about what would
constitute one. Only in retrospect do
we view the Wright brothers’ Flyer as
the essential breakthrough in manned
f light. Hot-air balloons had already
achieved flight, of a kind; gliders were
around, too, though they couldn’t take
off or land without a catapult or a leap.
One of the Wright brothers’ first manned
flights lasted less than a minute—was
that f light? An A.P. reporter said, of
that event, “Fifty-seven seconds, hey?
If it had been fifty-seven minutes, then
it might have been a news item.”
O
ur sun is a fusion engine. So are
all the stars.
But we discovered that fusion pow-
ered the stars only about a hundred years
ago, when the British physicist Arthur
Eddington put together two pieces of
