Fusion research was back in the news recently.
I’m actually pretty excited about this, I know I get excited about a lot of stuff but I really really mean it this time.
Scientists at the NIF or National Ignition Facility claim that they’ve overcome what appears to be the last major hurdle for the production of energy through sustained nuclear fusion. If this energy source becomes commercially viable, it could literally change the world providing it with a very safe, carbon-emission-free energy source from an abundant fuel supply that could last us millions of years. Sound good?
WHAT IS NIF
The National Ignition Facility is a huge machine at the Lawrence Livermore National Laboratory designed to bring the power of the sun to the earth. It’s a shining example of a national collaboration between industry, academia, and the US government. These scientists have been toiling away for the past decade building the biggest laser on the planet.
WHAT IS FUSION
Fusion literally powers the sun and by extension, the whole universe essentially.
Solar Fusion occurs at great temperatures and pressures which cause lighter elements to fuse together forming a heavier atom plus an extra bit of energy left over. They key idea here (for our purposes) is that more energy is released than it took to squish the particles together.
This process creates many of the lightest elements of the periodic table. The calcium in your bones was created this way.
Fusion also has the highest energy density of any process except for matter/antimatter annihilation. This makes it literally millions of times more energetic than chemical energy. This is because the energy binding an electron to its nucleus is trivial compared to the binding energy holding the nucleus itself together.
TYPES OF HOT FUSION
Gravitation is natures way of making fusion. Simply pile enough of the right kind of matter close enough together and the resulting heat and pressure in the core does all the work for you. This type of fusion reactor on earth won’t work though since you need more than the mass of jupiter to get it going.
Magnetic confinement is another way to get fusion going. Contain a hot plasma within a magnetic field and hope you can kick-off some fusion and not melt the walls of your reactor. This method has received by far the lion’s share of hot fusion research dollars for many decades.
Inertial confinement is the method the NIF is working on. It uses lasers to heat and compress a pellet of fuel in hopes it will start the fusion process.
NIF FUSION PROCESS
The NIF doesn’t focus one laser onto a fuel target. It focuses 192 of them. These lasers cycle back and forth within the facility getting stronger and stronger with each passing moment.
These beams eventually enter a spherical chamber and focus on a pellet of fuel at the center. This can create temperatures of 100’s of millions degrees Fahrenheit; hotter than the center of sun.
Did I mention that it took a decade to make this laser? How about this then; This laser is 60 times more powerful than any laser ever built. That’s what you need if you’re going reach the goal of Ignition. Ignition is not merely igniting the fuel, it means that fusion is hot enough to be self-sustaining. That’s the sweet-spot holy grail right there.
Three important challenges needed to be overcome if the NIF was to finally open their 10 year old bottles of champagne. One was the energy of the laser. I guess we know now that that check-box has been pretty-much ticked. Precision aiming was another big obstacle. Tick that one too.
LPI was one of the last challenges to be overcome. This stand for Laser-Plasma Interaction. It was long thought that the cloud of plasma created when the lasers initially hit its target would interfere with the precise heating of the fuel pellet. If that pellet isn’t heated uniformly around its surface, then this asymmetry could short-circuit fusion ignition and you have a dud instead of a ministar. What these clever scientists did was turn this minus into a plus. They used the properties of the plasma itself to fine tune the wavelength of their lasers so it heats their target more uniformly than ever.
This has allowed their most recent laser test to be such a success that Siegfried Glenzer, plasma physics group leader at Lawrence Livermore National Laboratory said the following
“When we extrapolate the results of the initial experiments to higher-energy shots…we feel we will be able to create the necessary…conditions to drive an implosion to ignition later this year,”
BENEFITS OF FUSION
The many benefits of fusion make it seem like one of those a too-good-to-be-true-types-of-tech.
It is safe; there are no carbon emissions; it can seamlessly be integrated into our current electric grid; there is little overlap with weapons technology (unlike a nuclear fission plant); and finally–the fuel used for fusion (isotopes of hydrogen) are in such abundance that they could last us millions of years
There are downsides but they aren’t nearly as down as fission reactors. For example: fusion creates less radioactive material than fission. What radiation there is also less biologically damaging. The halflives are measured not in thousands of years but tens of years.
Heck….it could take longer to pay-off your mortgage 🙂
There are critics of course but I sure as hell hope they’re wrong.
“They’re snake-oil salesmen,” says Thomas Cochran, senior scientist with the Natural Resources Defense Council. He also says that the NIF laser is still underpowered, too big, and too costly, and they’ll never be competitive.
Stephen Bodner, a Ph.D. physicist who was director of laser-fusion research at the Naval Research Laboratory in Washington, D.C., say Moses’s team has downplayed such technical problems as its inability to focus NIF’s laser on a tiny target.
It seems that some of these critiques are out of date since they appear to be resolved…i.e. the power of the laser and it focusing ability. The cost and size could be a problem however. No matter how great the fusion reactor is, if the the facility to house it and run it is too complicated, and too big and costly; then they will never proliferate the way they need to.
And boy do they need to.