By Michal Bartlomowicz

In our fast-paced and ever developing world, many issues are simply overlooked, neglected, and allowed to degrade. One such issue is already starting to pose societal problems because of our dependence on it: energy. The energy we use today is mostly nonrenewable, which means much of our energy supply will run out. So what is the solution? Sure, a few windmills might help, but conventional renewable energies just won’t do. What do many people believe is the real solution to the energy crisis? Fusion.

Nuclear fusion has long been considered one of the “holy grails” of science, since it promises near limitless energy for low costs. But what exactly is nuclear fusion? As the name implies, two light atoms, such as hydrogen, are combined, or fused, when there is enough heat and pressure. This forms a new, heavier element, helium. In the process, the fusion of the two atoms results in a small loss of mass in the product. And according to Einstein’s famous E=mc² equation, that tiny bit of mass missing from the helium atom is transformed into an amazing amount of energy. Fusion is what powers our sun, and ultimately gives us life.

But as it turns out, the sun is actually a really inefficient fusion reactor; we can build better, more efficient reactors here on earth. The only problem with fusion is that it is fairly difficult to achieve, since it requires an astronomical amount of heat: around 100,000,000°C, the same temperature as the center of the sun. Why so hot? The process of fusion goes against the very laws of nature: like particles repel each other, so it is very tough to get them to fuse together. Such a high temperature surpasses the coulomb barrier for the atoms, when their motion can overcome their repelling nature.

Methods for creating fusion here on earth, with the goal of harnessing its huge energy, is currently divided into two branches: magnetic and inertial confinement. Magnetic confinement fusion uses heated plasma, where as inertial confinement fusion uses massive lasers.

Plasma, know as the fourth state of matter, is when a super heated gas becomes ionized; atoms lose their electrons and become charged nuclei. Since plasma is ionized, it can be manipulated with magnets. But if you’ve taken chemistry in Pomperaug, you’ll know that as you raise the temperature, atoms start to move more, and therefore are harder to contain. Fusion reactors, therefore, have to have very powerful magnets. In order to effectively contain plasma, shapes like a torus, or a doughnut-like shape, are used to circulate very hot plasma. But even this isn’t effective enough. The most successful designs used to date have used tokamak magnetic geometry, which essentially spirals the magnetic field around the torus.

In fact, it is impossible to contain plasma with current technology. Fusion reactors are like buckets with large holes in them; plasma escapes very rapidly. Most reactors have mere fractions of a second before the plasma dissipates. How do you make a bucket retain something longer with that big hole? Make the bucket bigger, and it will simply take longer for it to drain. The largest reactors today can have fusion for about one or two seconds.

Over the summer, I actually had the opportunity to visit such a reactor as part of an engineering program. Located in Cambridge, Massachusetts, MIT’s Plasma Science and Fusion Center (PSFC) has one of the most successful reactors in the world, the Alcator C-Mod. The “compact” reactor is pretty big, being some 25 feet tall. The magnets have the strength of 5 Teslas, or 100,000 times the Earth’s magnetic field. So in order to keep it from collapsing in on itself, the reactor is held together by a two feet thick slab of steel, which is bolted on with 96 bolts, two of which could hold back the space shuttle from lift off. The actual reactor is off-limits, especially during testing due to both high radio radiation and neutron radiation. Since heating plasma to over 50 million degrees Celsius in a few seconds takes a lot of energy, about the same amount as the entire city of Cambridge, the machine “charges” for around 20 minutes. When “fired,” the reactor bombards the plasma with high energy radio waves, quickly heating it to the required level. But after a few seconds, the experiment is over, an eternity in the world of fusion research. Cameras are even placed inside along with numerous research instruments, and every time the experiment is run, a plethora of information is gathered.

Oddly enough, a “proper” fusion reaction does not occur every half hour in the heart of MIT’s campus. In fact, the PSFC doesn’t even use the right fuel. There are two reasons for this: deuterium and tritium (isotopes of hydrogen that make fusion easier) involve the radioactive isotope of hydrogen, tritium. Because of this, only deuterium, or heavy hydrogen, is used. Theoretical yield is then calculated. The second reason has to do with the capability of the reactor. Like all others today, less energy is produced than was put in. The best fusion experiments in the world have are reaching the breakeven point, but aren’t quite there. Even if more energy comes out, the process won’t be economical until about 40% more energy is produced, named the point of ignition, where the fusion reaction is kept hot by its own heat, essentially fueling itself. The only device ever to ignite fusion was the hydrogen atomic bomb. Needless to say, that isn’t the best way to solve the energy crisis.

That’s where the ITER comes in. The International Thermonuclear Experimental Reactor is a multibillion dollar join project between the USA, the European Union, Japan, China, Russia, Korea, and India, and the first fusion reactor planned to produce net power. Still in construction, the reactor located in France will be truly massive, and is predicted to maintain fusion for 500 seconds. Later planned projects, like DEMO (Demonstration Power Plant), hope to sustain fusion constantly.

On the other hand, there is another project, located in California that plans to start ignition experiments this year. The National Ignition Facility, or NIF, takes a different approach; instead of using massive magnets and plasma, the NIF uses a large array of powerful lasers, 192 in all, to concentrate about 500 terawatts of light energy, or 50 trillion times the power of a common 50 watt light bulb, onto a single pellet of hydrogen fuel for a trillionth of a second. The experiment starts by firing each laser, which then get focused and amplified, until reaching the fuel pellet. The intense laser beams then concentrate on the gold lining of the pellet, which heats up the pellet, creating an implosion shockwave that fuses the hydrogen fuel. In order to be economical, the NIF would have to fire several times a second, which is currently impossible.

Although the dream of having a world fueled by a clean, and almost limitless energy source is still many decades away, research is currently underway to make the dream a reality. But perhaps the most exciting thing about fusion research is that fusion power is likely to happen within our lifetimes.