This is the world’s brightest x-ray laser.
At the time of its first light in 2009, the Linac Coherent Light Source generated x-ray
pulses a billion times brighter than anything around. The LCLS is a tool unlike anything
before it. We're able to deliver these pulses of x-rays in one millionth of one billionth
of a second. This MASSIVE MACHINE allows scientists to take ultrafast snapshots of the INVISIBLE
WORLD, imaging MOLECULES AND ATOMS, documenting how they change and evolve over time. But
the LCLS maxes out at 120 pulses per second. So to see the ultra small world like never
before, scientists and engineers are building something new. The LCLS-II is going to take
the free electron laser field up another quantum leap. This will be unprecedented and will
allow for a beam that's 8,000 times brighter than the LCLS beam at
this million pulses per second. At this national lab, hidden deep underground, scientists have
been conducting groundbreaking research for decades. The whole tunnel and the whole building
that we see here, is about three kilometers long and the original project used that full
three kilometers. Currently, the LCLS accelerator is in the final kilometer.
The LCLS is short for the Linac Coherent Light Source. It's the world's first hard x-ray
free electron laser. The LCLS uses a particle accelerator to fire extremely bright electrons
to create fast pulses of hard x-rays, which is why the machine is called an x-ray laser.
Back in the '90s at SLAC they figured out a way to turn those super bright electron
beams into very intense and bright and powerful x-ray laser pulses. We have ultraviolet lasers
trained and aimed at this piece of copper, and we pulse that optical laser about 100
times a second creating an electron pulse. We channel those electron pulses into the
accelerator. The accelerator then uses big, longstanding technology called klystrons.
And we can think of them as microwave ovens, and the microwave ovens basically accelerate
these electrons. And as we accelerate those electrons what makes the LCLS really go, are
what are called undulators. If you take an electron through magnets, the electron bends
and when it bends it gives off x-rays. We then are able to focus the x-rays into different
sample materials. Whether that sample is an amino acid, or graphene, or supercooled water,
it gets frozen in time by strobe-like pulses, which last for just a few femtoseconds. A
femtosecond is a quadrillionth of a second. It's one millionth of one
billionth of a second. We would picture that as a one with fifteen zeros in front of it.
This time scale allows scientists to track the motion of atoms! Allowing researchers
across disciplines to probe the far reaches of our scientific knowledge. Empowering them
to make “molecular movies” that show chemistry in action, study the structure and motion
of proteins for next generation drugs and image quantum materials with unprecedented
resolution. It's a tool for exploration. It really allows for transformational science in chemistry, biology,
and physics. The LCLS-I, if you would like to say, the original build, was great to look at how molecular structure
is evolving through time using bright x-rays and taking snapshots. But researchers wanted
to go BEYOND looking at molecular structures. And they wanted a machine that fired EVEN
FASTER! The LCLS-II accelerator is a superconducting accelerator designed to produce a very intense
burst of x-rays at a very high repetition rate. We're talking about magnitudes far greater
than its predecessor. This new accelerator will go from 120 pulses per second up
to 1 MILLION pulses per second! Which means more shots per second allows you to collect
more information in a shorter period of time, which helps boost science output. But it’s
not just about quantity. It’s about what we can see with the LCLS-II. With LCLS-I,
we will look at the structure. On LCLS-II, we might want to look at how the energy flows
through those degrees of freedom in that system. The LCLS-II will be able to image
atoms, molecules, and subatomic interactions at greater resolutions thanks to its superconducting
accelerator. For LCLS-II, we will be installing 37 cryo modules. Each of our cryo modules
in the tunnel is roughly 12 meters long and each has eight accelerating cavities inside
of it. We're using these new niobium cavities. They're superconducting and the way we get
them superconducting is we bathe them in liquid helium. So it's two degrees above absolute
zero, where in principle, all motion stops. This ultra cool upgrade is a big change from
the LCLS, which uses a copper accelerator and operates at room temperature. Superconductors,
when you cool them down cold enough, they have no electrical resistance. So they don't
heat up at all. Since you're not heating your structure up, you can run it continuously.
In our case, this allows us to make the jump from 120 pulses per second up to a million
pulses per second. But installing 37 twelve-meter-long cryomodules inside a narrow, underground tunnel
nine meters below is no easy feat. This is a cryomodule here. It's 40 feet long, so we do string all them together, so they're in three different strings. The one that we're standing in front of right now is by far the largest. As engineers, we have to come up with some clever ways of
just how to fit all of these big pieces of equipment through the tunnel and maneuver
around them to make sure that they're installed properly. The installation itself, right now,
is about 95 percent complete in the tunnel. In addition to having a new, superconductive
accelerator, LCLS-II is also getting new undulators, which will create magnetic fields TENS OF
THOUSANDS times stronger than the Earth’s magnetic field. So we are inside the hutch called the TMO instrument. This is one of the very
first stops for the LCLS-II superconducting beam when it comes online. And what this is
really tuned to do is to look at the dynamic properties of how energy is transferred from
one state to another. Once operational, the new accelerator is capable of producing more
x-ray pulses in a few hours than the LCLS has produced over its entire lifetime! — generating
terabytes of data each second. All this new power will undoubtedly lead to an influx of
breakthroughs and discoveries. As we scan through time, we're able then to map out how
these molecules break apart, and that tells us something about fundamental AMO physics.
Another aspect of it is looking at how the energy flows through quantum materials. But
even with this new accelerator’s exciting potential, that doesn’t mean the LCLS is
going anywhere. The LCLS is here to stay. What LCLS-II will provide is really a compliment.
So the two machines will continue to work together. With LCLS operating in a harder
x-ray regime and LCLS-II providing what they call soft or tender x-rays, which really allow
you to probe different states of matter at this much higher repetition rate. The new
accelerator will take over the first kilometer in the tunnel, while the original will remain
in its current position at the end. The LCLS-II is currently on target to get “first light”
in summer 2022. It's really cool to be able to come here and work on a machine that's
really going to help people, really going to help scientists make all these great discoveries.
One of the most important things for big science experiments is planning for the future. LCLS-II
is being built at a key time in x-ray science. What LCLS-II can provide really is groundbreaking
and addresses an area that can't be identified or worked on at any other facility. Now that
we know that we have this source that's going to enable much more science, we're going to
tackle new, harder scientific fields, and so we're just not going to be stagnant and
just say, "Oh, we can do that experiment that much better and that much shorter in time."
No, we want to go for the hard stuff, and so we're going to have to really look at and
utilize that new superconducting source to its fullest.
