Hello, and welcome to the Physics World weekly
podcast.
I'm Hamish Johnston.
My guest is the plasma physicist,
Debbie Callahan.
She spent thirty five years working at the
national ignition facility
at Lawrence Livermore
National Laboratory
in The US
before she joined
Focused Energy,
a California and Germany based fusion energy startup.
That conversation is coming up after this message
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Broadly speaking, physicists and engineers
are exploring
two different ways
of generating energy from nuclear fusion.
One involves using magnetic fields to create and
maintain
a plasma of hydrogen
that is so hot and so dense that
its nuclei can fuse together,
releasing huge amounts of energy.
The other involves firing intense
laser pulses
at a hydrogen target,
compressing and heating it to achieve
fusion.
Focused Energy is taking the latter approach,
and I'm very pleased to be joined by
Debbie Callahan,
who is the company's chief
strategy officer.
Hi, Debbie.
Welcome to the podcast.
Hi, Hamish. It's nice to be here.
So, Debbie, you spent thirty five years at
the national ignition facility
at Lawrence Livermore
National Laboratory.
Can you explain how fusion is achieved at
NIF
and how that differs from the approach
taken by magnetic confinement
facilities
such as ITER, which is being built in
France?
Yeah. Sure.
In order to get fusion to happen, you
need sort of three elements,
that we sometimes call the triple product.
So you need a a a certain amount
of density in your plasma,
you need temperature,
and you need time.
And so the product of those has to
be over a certain value. So magnetic fusion
and inertial fusion
are kind of the opposite of each other.
So in a magnetic fusion,
you have a low density plasma, but you
hold it for a long time. And you
do that by using magnetic fields
that, you know, trap the plasma and keep
it from escaping. And so that's what's being
done on ITER and other magnetic fusion
facilities.
In inertial fusion, it's the opposite.
We don't hold the plasma together at all.
It's only held by its own inertia. That's
where the term inertial fusion comes from.
But we have a very high density. So
we have a very high density for a
short time. Magnetic fusion has a low density
for a long time. And so in both
cases,
you can,
make fusion happen.
I see. And and what is the state
of the art,
at the moment at the national
ignition facility?
You know, just in terms of of how
much energy you have to put in to
achieve
fusion
versus the amount of energy that you get
out?
So the best shot to date on NIF
has achieved a target gain of four just
over four, about 4.1.
And that used about two megajoules of laser
energy, so about eight megajoules, a little over
eight megajoules
out.
This is a tremendous scientific accomplishment,
you know, that's taken us a long time
to get to, and super exciting.
You know, for
to make energy, for inertial fusion energy, we
do need significantly higher gains,
gains of something like 50 to a 100.
So we're at four, but we need to
get to 50 or a 100, in order
to make a pie power plant out of
fusion.
I see. And and that I suppose that
takes us, very neatly
to my next question.
You've since made the move to industry,
and your target design lead
at, a California based company called Focused Energy.
Can you can you give us a brief
history of the company
and its approach to fusion energy?
Yes. Absolutely. So Focused Energy,
started in 2021.
Ironically,
the company was founded one month before we
achieved scientific
ignition,
which is not the same as as GAIN
greater than one. We achieved that in August
2021,
and the company was founded in July. So
good job from our our founders.
The
the company is has offices in The United
States and in Germany.
In Germany, particularly,
it's in Darmstadt, which is near Frankfurt.
And our approach is to use what we
call laser direct drive,
and that's as opposed to what's done on
NIF, which is called laser indirect drive.
And the difference between that is in what
what we did on NIF is we put
the lasers into a small cylinder
of
of gold or depleted uranium and convert those
that laser energy into X rays, and the
X rays drive the capsule.
For our company, we're,
directly driving the capsule. That means the laser
energy is put directly on the capsule. There's
no intermediary
of the X rays as you have an
indirect drive.
The reason for doing that is that,
that
converting to X rays is, not very efficient,
and so it makes it much more difficult
to get the high target gains that we
needed that we just talked about a minute
ago.
And so we believe that
that direct drive is
the the best, option to go for for
fusion energy to get us from that gain
of four to the gain of 50 or
a 100 that we would need for a
power plant.
I see.
And in terms of efficiency, I mean, at
Lawrence Livermore, you have access to
extraordinarily
powerful
lasers.
And,
I mean, I suppose
even if you could build a power plant
based on the technology there, you would you
would still need these huge lasers, and I'm
guessing it would probably
not be a very efficient
system overall.
Is is that the sort of the key
goal,
you know, with what you and your colleagues
are doing in industry now? You're trying to
boost this efficiency,
as much as you can to make it
a sort of a practical thing that can
run at an industrial level.
Right. Exactly. That's exactly right.
You have to remember that the NIF, the
natural ignition facility,
was funded for national security purposes, not for
fusion energy. And so it wasn't designed,
to be a power plant,
and have all the elements we need for
a power plant.
In particular, the laser is very inefficient.
So, again, for fusion energy, you know, for
power generation, we believe we need to have
the laser be about 10% efficient.
NIF is less than 1% efficient, and that's
just because that wasn't the goal.
The goal was to do this for the
first time.
And so that's one of the big thrusts
of our company is to develop,
more efficient lasers that are driven by diodes.
They're called diode pump solid state lasers,
which will be much more efficient than MIF,
and that's required
that's one of the elements that's required for
fusion energy,
that we're that is a big thrust for
our company.
And can you talk a bit more about
focused energies?
Well, well, I suppose the two technologies that
the company is developing. One is called
Lighthouse,
and the other is called
Pearl Fuel. Can you can you tell us
a bit more about those two technologies?
Yeah. So the thing we call lighthouse is
our fusion. We call another term for it
is the fusion pilot plant.
It will be the first,
power plant that will produce what we call
engineering gain greater than one. That means that
it will produce more energy than the electricity
that it took to drive it. So remember,
on NIF, it's the amount of energy out
is relative to the amount of laser energy.
But as we just said, the laser is
very inefficient. And so
the the engineering gain, the amount of electricity
we had to put in to produce that
eight megajoules
of fusion energy is, you know, is a
lot.
And so we're now targeting engineering gain where
we actually produce
net electricity.
And that's what will be done in that
lighthouse,
fusion pilot plant. So that will be the
first demonstration.
So the pearl is the capsule. That's the
piece that holds the deuterium and tritium fuel,
that we that we implode to
fusion conditions. That's similar to what we did
on NIF.
There there was a capsule inside of that
holoron. We talked before about the holoron that
converted the laser light into X rays.
So the capsules are similar,
but, you know, they're different in that it's
direct drive. So there's there's differences
there's differences and very many similarities.
So so when you talk about the capsule,
I suppose you want the the capsule to
absorb
the laser energy and and give as much
of that energy to the fuel
as possible. Does it so I'm guessing that
the the material that you make the capsule
out of and its shape are very important.
Are those the are those the the two
key
parameters that you have to deal with when
you're developing
the capsule.
Yeah. The the that's correct. The,
the development of the capsule for a fusion
power plant is actually quite complicated
because,
as you say, we need it to be
very spherical,
because it needs to compress spherically.
The materials need to absorb the laser light,
efficiently in order to, you know, minimize the
size of laser. But then you have to
realize we have to be able to produce
these targets.
And, you know, so while NIF does about
400 shots per year,
we need to do about
900,000
shots per day. We need to operate at
a at a repetition rate about 10 shots
per second.
So it needs to be something that we
can manufacture
cheaply, quickly.
And so that goes into it as well.
And then the last piece is after the
target explodes,
it goes into the reactor
chamber, efficiently
so that we can, you know, clear the
chamber to make the have the next shot
happen.
So the actual design, which is this is
kind of my area. That actual design is
actually very complicated. It involves
bringing together all the pieces of the power
plant and making sure we have a design
that's consistent with with everything.
I see. And and when you're when when
you're doing the design,
do do you have I'm guessing you're do
do you do a lot of computer simulations?
Is that,
is that does that take up a a
lot of your time, or do you spend
a lot of time in the lab
testing these,
whole ROMs,
in actual laser conditions, or is it a
bit of both?
Yeah. Remember, the whole ROM part was for
NIF, so we don't use a whole ROM
at all. Oh, okay. Right. But,
but you're correct. Computer simulations
play a large role in us developing these
designs.
Although one of the lessons that that I
learned from NIF was that
although the simulation codes are state of the
art,
very,
well developed, many decades of work have gone
into them.
Doing an ICF implosion,
requires us to to know these answers
to a very high precision,
And the codes are just not quite good
enough, so we really do need experimental data.
And that plays a huge role,
in in optimizing
what this design looked like. And that's actually
what happened on NIF. We realized that we
needed to really use that data as well,
in order to get to Ignition, and I
expect the same will be true.
I think the third leg that's coming up
is,
you know, AI machine learning at
Livermore that, you know, there's a a project
working on that that contributed to getting to
Ignition.
I only see that getting bigger.
And as we are able to do higher
repetition rate
experiments, we'll get more data.
And I think that that will even play
a bigger role. One of the limiting factors
on NIF is if you only can do
a few shots, you don't have a lot
of data to train on. But as we're
able to develop these high repetition rate facilities,
we'll be getting loads of data, and that
will, I think, open up a brand new,
doors for machine learning and artificial intelligence to
help us figure out how to optimize the
design.
And, I mean, in terms of, you know,
the company's
key
intellectual property, then it is
the design of the target
and
the design
of how the lasers
strike the target, or,
are are are those the two sort of
important things? The design of the target being
the pearl,
and the design of how the target is
struck being the lighthouse
side of things.
Yeah. There's also,
intellectual property in the design of the lasers
because, remember, these are not the same lasers
that we used
on NIF.
Also, how we fabricate the targets, I think
there'll be a lot of IP there. I
mean, it's actually pretty complicated to figure out
how to build,
you know, 900,000
targets a day. That's just a, like, a
daunting number,
and have them come in at at a
price.
You know, the price of the target is
important component.
And so have those come in at a
price that is will make the cost of
electricity competitive.
So those are kind of the areas that
I think we'll where we'll see a lot
of IP,
coming out of this kind of a project.
And then the the act of putting it
all together, I think, is also important, how
we integrate those things together,
in order to make a successful plant.
And you you mentioned cost. The so so
you're using deuterium and tritium
as as opposed to,
hydrogen.
Are are those are those materials,
you know, are they very expensive,
or are they difficult
to work with? I mean, I suppose tritium
is is a radioactive
material, so that's that makes it difficult
to deal with.
It it
are are those, challenges for the company?
Yes. Absolutely.
We choose deuterium and tritium because they are
the easiest elements to fuse.
And so
advanced fuels have have some advantages, but it's
just much, much, much harder.
And so let's start with the thing that's
the easiest. It's also the thing we demonstrated
at NIF. NIF also used deuterium tritium fuel,
so we know it works because we've we've
demonstrated that.
The way we get the fuel, deuterium is
actually can be found
naturally.
In seawater, you can you can get deuterium
from there. The tritium, as you say, is
the more complicated one. Tritium, we breed in
the reactor,
from lithium. So our reactor designs have lithium
in them, and the neutrons from the,
fusion reactions actually breed the tritium.
Getting enough tritium, making sure that we have
enough tritium,
and figuring out how to extract that tritium,
and,
then, of course, use it for future shots
is a big area. We, in fact, just
started a collaboration
that,
was funded by Department of Energy for us
to work with Savannah River National Lab.
And they have a lot of expertise in
designing these tritium this tritium extraction systems, tritium
fuel systems.
And so we look forward to working with
them,
on that project.
I see. So so so
when the technology is up and running,
it will be
I mean, will will it produce enough of
its own
tritium?
Will would it be sort of self funding
when it comes to tritium? Is that the
plan? Exactly.
Exactly. I mean, that's a requirement. I mean,
we have to be able to
breed enough tritium,
to keep the plant going.
And so that is part of the design.
Okay. And I just wanted to ask you
finally about
the
the you know, how how to get the
heat out. I mean, you mentioned the neutrons,
interacting and and producing
tritium. But those, if I'm if I'm not
mistaken, those are the interactions that
ultimately would produce the heat that you would
like to capture,
and then maybe use that to generate electricity.
If you,
is a a a sort of a heat
exchange mechanism part of your design, or are
you solely focusing
on getting the, fusion
reaction right at the moment?
No. We're also working that's part of the
reactor design is that, you know, those neutrons
are stopped in something we call the blanket,
which
breeds the tritium, but it also captures that
heat.
And then
at the end of the day, we go
to a traditional
system to produce electricity. Essentially, you boil water
and,
and produce electricity in sort of the conventional
way. It's it's a little funny. You've got
this very high-tech
way of of producing heat, but at the
end of the day,
we go back to conventional methods for producing
electricity.
Yeah. It's I I it's well,
it's just just
a very fancy water heater.
I'm obviously not doing it justice by saying
just.
No. But, you know, as you say, that's
right. At the end of the day, that's
what it does.
And
is it possible to, to to say what
what the timeline is on on this development?
Yeah. So our plan is to have a
a a pilot plant up,
in
by the end of the next decade, by
the end of the thirties.
It's a fairly aggressive timeline given the things
that we have to do,
but, you know, that's part of being a
start up, I think. We have to take
some risks and try to move quickly
and try to achieve our goal.
I see. And that that would be
on your premises, or would it be in
collaboration with
a a national lab like Lawrence Livermore?
Or is it a pure would it be
a purely private endeavor?
I I think that's a bit TBD.
Where we will cite it and, you know,
what the partners will be.
I mean, obviously, we have partners helping us
build
and build the system. We have partners with
laser companies, as I mentioned I just mentioned
Savannah River. We have other partners. One of
one of our kind of, in my view,
superpowers of our company is because we have
one foot in in Europe and one foot
in The United States.
We actually have brought together a team from
across
it's not just Germany, but
also other places in Europe,
as well as The US. And so we
have a lot of
opportunities,
between those two continents,
to partner
with other companies,
to governments,
etcetera.
And so
I think that makes us strong
because we have some of the best talent
from around,
around the world.
And, Debbie, I wanted to ask you,
I I suppose this is a a almost
a a career
question rather than,
about the company and and fusion technology.
The the fusion industry, I suppose, is having
a bit of a renaissance at the moment,
isn't there? Isn't it? There's lots of smaller
companies
that have come in and, and you've got,
you know, big big players like, ITER
in in France.
Just curious from from your point of view,
you you you had a a career in,
I suppose, academic research, although
you're at Lawrence Livermore rather than
at a at a university.
How does your role,
at Focused Energy
today compare with,
what you were doing as a researcher,
at the National Ignition Facility.
Is it, it it is it sort of
similar, or is it very different?
What's it like? You know,
compare a day at Focused Energy,
to a day at Lawrence Livermore.
There's a lot of similarities.
Working at at NIF,
there was a lot of pressure. We were
trying to move very quickly, so that's kind
of similar to working in a startup or
at Focused Energy.
You know,
my role is to bring what I learned
from NIF and the skills that I have
to our problem at Focused Energy. And so,
you know, that is that is kind of
a natural transition from what I did before
to what I'm doing now.
I think the one of the big differences
for me is a level of bureaucracy.
You know, working for a government
funded lab, there was lots of rules and
lots of paperwork, and,
you know, that that takes up your time
for things that you might not always see
the value in.
And working now for a small startup, we're
able to just move more quickly. We're able
to you know, we just don't have a
lot of those kind of constraints. I mean,
obviously, there are still some constraints, but we,
you know, we're able to make progress more
quickly, in that way. Personally, I find
that great because
it's just it just makes
more time for the things that are fun,
which is trying to get fusion on the
grid.
And and finally, Debbie, what, what advice would
you give to,
an early career physicist?
I mean, maybe this is somebody who's just
finished
a bachelor's degree, or maybe they've just done
a PhD,
and they're really keen on joining
the fusion industry.
What what would your tips be,
you know, to get a career like that
going?
Yeah. I think there's
very, very many opportunities
right now.
You know, when I started, it was mainly
just universities
or national labs. Those were kind of our
choices.
But now with these companies, there's there's a
lot of companies that have sprung up. Now
probably all of those companies will not survive,
just because there's only so much money.
But there's lots of opportunities, and, yeah, I
would say go for it.
I was speaking with someone,
a few weeks ago from,
one of the universities in Texas who's a
beginning graduate student. And,
you know, you're joining this field where there's
just lots of opportunity. It's
new stuff every day. There's new problems.
So if you like problem solving, it's great.
You know? If you wanna do something good
for the world, you know, hopefully, that's what
we will do. That's our goal.
And,
I would say there's also gonna be opportunities
for people other than people like me, other
than, you know, PhD plasma physicists
because
we're also gonna need, you know, people who
know about lasers.
We're gonna need technicians. We're gonna need operators.
You know, there's gonna be just a tremendous
growth in this field.
And, you know, so, you know, that's great
because there's just gonna be lots of opportunities
for young people to join us,
in this quest for fusion.
And I I wanted to ask you about
that,
you know, specifically at Focused Energy.
You know, if if somebody was lucky enough
to to get a job
at Focused Energy, who who would they be
working
alongside? I mean, there would be some plasma
physicists, but would there also be, engineers,
maybe
a mathematician or a computer scientist
who specializes
in in doing simulations? What what what sort
of colleagues
could would somebody expect to have at the
company?
Yeah. We have all the people that you
just talked about. We have people who work
in lasers. We have people who work on
the reactor design.
We have people who work on target physics
like me.
We have a large
group of people, quite,
advanced lab that's working on building the targets,
which in itself is, you know, as I
mentioned before, I think is quite a challenge.
Engineering,
of course, we need engineering to put all
this together.
So there's there's a lot of opportunities
for people who are in a lot of
different fields.
You also mentioned, I think,
you know, as I said before, I think
AI and machine learning, we're
working on putting together a digital twin that
will, you know, try to model the whole
system
in
in in one model.
And that's also an opportunity for people with
with those with that kind of background.
So there's lots of lots of opportunities out
there.
And and what about,
I suppose,
you know, still participating
in in academic research, do you
do you collaborate
with,
researchers at, you know, for example, at a
place like, Lawrence Livermore or maybe
universities? And, you know, does your name appear
occasionally,
in an author list
on a paper about fusion? You know, are
are you sort of still out there, let's
say, doing some academic research, or is it
mostly
very focused on on commercial,
issues at Focused Energy?
No. We are still out there. In fact,
in a couple months, I think we have
four presentations
at the American Physical Society
division of plasma physics meeting.
I mean, one of the things that, you
know, again, I feel fairly strongly about is
that peer review is important.
We're trying to do something that no one's
done before. And so having,
you know, our colleagues
be able to give us feedback on what
we're doing or point out mistakes that we're
making or things that we're forgetting about
or just,
and then also collaborating. And we have collaborators
both in Europe and in The US,
with
universities
or other net or national labs.
And, you know, those things, I think, are
important to try to to get where we
wanna go. So, yeah, we are still out
there. You know, publishing isn't our, of course,
our number one priority.
But, again, I feel like peer review is
is quite important, and so we are doing
that.
So you still
you still must feel a part of the
fusion community then,
from an academic,
in an academic sense.
Absolutely.
And that's also good for recruiting because, of
course, when we go to these meetings, we
also we're giving presentations.
Students are hearing our presentations, and we're meeting
those students, and those might be future employees
of our company.
Great.
Well, thanks so much, Debbie. Thanks for coming
on the podcast and, and talking about your
work at Focused Energy. It sounds really, really
fascinating. And, you know, as you said, it
seems like
a a bit of a moment for for
the fusion industry. And, hopefully, hopefully, somebody will
crack it. Hopefully, it'll be it'll be you
and your colleagues.
So thank you. And, yeah,
I hope that that your research and development
goes well.
Thank you so much for having me on.
I I've enjoyed this. It's been fun. And
and, so thank you.
I'm afraid that's all the time we have
for this week's podcast. Thanks to Debbie Callahan
of Focused Energy
for joining me today, and a special thanks
to our producer, Fred Isles.
We'll be back again next week. And if
you have an interest in radiotherapy,
don't forget to register for our upcoming webinar,
unlocking
novel radiation
beams for cancer treatment
with upright patient positioning.
It will be presented
on the February 17
at 4PM
GMT.
That's 11AM
Eastern Standard Time.
You can register for this free event on
the Physics World website.