MAN 1: The computer models suggest that if we don't find
a non-fossil fuel form of energy soon,
then climate change is irreversible
and we've got to figure out how to deal with a warmer Earth.
Fusion is clean, no greenhouse gases,
no long-lived radiation that we have to fight about
where we're gonna bury it,
and because the Earth is two-thirds covered in water
and the hydrogen in the water,
here you get to the unlimited supply of electricity.
Some people believe our community and some people don't,
'cause if you hear about this, you go wait a minute.
Either this is too good to be true
and there's no possibility,
or you're left with, this is crazy.
This is the most important thing
that we could be doing scientifically.
Wipe out disease and hunger and make a source of energy
that never, ever runs out, right?
And offer it to the world.
MAN 2: So fusion is when you combine two small,
very small particles together like hydrogen, right?
Then the final combination, which is a helium atom
with one neutron coming out,
ends up being at a lower energy state.
Hence it releases energy in the reaction.
It's energetically more stable.
That wants to happen.
So why is it hard to get there?
Because of the coulomb potential, right?
As you get two positive charges close together,
all they would want to do is repel.
You need to get in close enough
for the nuclei to touch each other
and have this nuclear strong force take over.
It's an attractive force that's stronger
than the electric repulsion,
and that will only happen by chance.
It'll only happen when you get particles
in a soup that's hot enough so that every once in a while
two protons are heading towards each other
with enough energy such that before they get repulsed,
the strong force takes over and grabs it
and creates a new atom.
MAN 1: If the energy is not high enough,
then the probability is either zero or very low.
And if the energy's too high,
it's also very low and there's a sweet spot.
Otherwise they won't fuse.
MAN 2: Okay, how does the sun do it?
Let's start with that question.
Well, it's got a whole bunch of particles.
They're moving very fast
and then the gravity from the sun is going, come here.
Don't go out, keep on trying, keep on trying, right?
MAN 1: It's in beautiful equilibrium.
The sun is the balance between that pressure
of the radiation out and the gravitational force going in.
MAN 2: But we are in trouble
because we can't do that, right?
We need to have a better way of confining the plasma.
It's just gonna either melt the walls
or the walls are gonna cool down my plasma.
MAN 1: So the big question becomes
what's the right container.
MAN 2: So the way we do it is with a donut.
MAN 1: That's what this laboratory's doing,
is making a bottle.
It's a magnetic bottle, right?
MAN 2: Now in a plasma, what you get is a soup
of a whole bunch of charged particles,
electrons and positive ions floating around.
When a charged particle is inside a magnetic field,
it starts spiraling around it
because the force is perpendicular to both the velocity
and the magnetic field.
That's why if we put a magnetic field
that eats its own tail, now it's stuck
without touching the walls.
So that's the crucial part of magnetic confinement.
So it's like the jelly in a donut
not being able to touch the glaze
because the magnetic field is right down
in the middle of the jelly
and it won't let the particles diffuse out
towards the glaze.
WORKER: There's helmets here.
MAN 2: Do I need to wear one? WORKER: You do, yes.
We can go over here.
When making plasma, there's kind of a complicated
time history of how we do it.
So NSTX has, like all magnetic fusion machines at least,
vacuum chambers and magnets.
So that's the top of the vacuum chamber.
That's a completely sort of large cylindrical shaped
vacuum chamber, and then in red here coming out of the top
and going down are magnets.
So those are called the toroidal field magnets.
And in blue, if you look there,
you can see poloidal field magnets.
So the blue are big circular magnets.
How do you make a plasma discharge?
We start with the vessel pump down,
very low pressure in there, no magnetic fields,
just sitting there inertly.
Then what we do is we turn on these red magnets,
the toroidal field coils, and they make the field
that goes around the torus this way.
The blue coils make a field that points up.
That blue one right there, it's got current,
and we leave them on without changing their current values
for the duration of the plasma discharge.
So they're on and they stay on.
Then we turn on at the same time,
we drive some current in our solenoid
as we charge it one way to about 26 kiloamps of current.
Then we rapidly decrease the current in the solenoid,
and as we very rapidly turn it off,
that's what drives current in our plasma.
Maybe there's a few random charged particles in the gas.
They're accelerated by the electric field.
Maybe they hit another particle and they hit an atom
and they ionize it.
Now you have more charge particles
so they can go off and hit things,
and it's an avalanche process.
And that's how you start by making this electric field
and you can drive it into making a full plasma.
So we got plasma there.
It's not as hot as we'd like,
so then we inject the neutral beams.
So straight beam of deuterion atoms,
three beams each of which is 2 million watts
for six, aggregate of 6 million watts,
and those beams, the energetic particles in the beams
scatter and collide and transfer their energy
to the bulk plasma.
It takes about 300 milliseconds
to sort of form that whole process.
And then for 600 to say 1.5 seconds,
600 milliseconds to one and a half seconds,
it's kind of just sitting there, steady state.
It just sits there and we study it.
Temperature's about one kilovolt,
and that's like 10 to the fourth times,
it's like 10 million degrees.
MAN 1: So all the machines you saw today,
before you talked to us,
were just different ways to make a magnetic bottle.
There's other people you can read about
that use electric fields, they use lasers
or whatever it might be, but in the end,
because we can't use gravity,
we gotta do it some other way.
Because there's two questions, right?
There is the can we build the machines
that can do this, right?
That's the first question.
And we say yes, and we can debate that scientifically
and we can debate the engineering and the technology
and all those sort of things, right?
But that's not enough to make usable electricity.
You also have to have everything else in place
so that the energy that you create
has to be competitive economically with the fossil fuels
or with fission or with solar or with wind.
I mean, if we get there, and we will get there,
it's a game changer.
That part's not the hype.
So why don't we have it and how long is it gonna take?
I would say currently the answer is never,
unless we are really serious about funding this.
If we are wrong and we can't do it,
then the planet goes on to whatever it does, right?
If we're right, it changes the planet as we know it
because it's a completely new paradigm
in a source of energy, right?
So the question becomes are we willing to take the risk
to find out if we're right?
I mean, don't you want to be a part of something
that changes the planet?
That's the bottom line.