In the first part we discussed about the thrusters of Iron Man. If you haven’t read the first part yet, then go check it out here. Okay, so now that you have done that, let’s get started.
This part is quite interesting and to some extent ‘environment-friendly‘. Here’s one question. Where does the energy needed to power the Iron Man suit come from? To answer that, we need to understand the ‘arc reactor‘ of Iron Man’s suit. Let’s explore it.
Iron Man’s ‘ARC REACTOR’
Now before we proceed further and understand how this arc reactor works, let us understand the basic principle behind all this.
Nuclear Fusion Energy
Nuclear Fusion is a process of combining two lighter atoms into a much heavier atom to produce unprecedented amount of energy. This process occurs naturally in the core of the Sun and stars. Hydrogen is the main fuel for this to happen. The temperature of the Sun’s core is about 15 million degrees Celsius or even higher. When hydrogen is heated to very high temperatures like this, it changes from gas to plasma. If you want to know more about plasma, then check out my blog post explaining what plasma is.
When hydrogen is converted to plasma, the electron is separated from the nucleus leading to the formation of positively charged ions. These positively charged hydrogen atoms fuse together to form helium which is comparatively higher in mass than hydrogen. The mass of helium is not exactly the summation of masses of the hydrogen atoms fused, but instead it is much less than the summation of their masses. From this we can understand that some of the mass of the hydrogen atoms is converted to tremendous amount of energy which is evident in the form of Einstein’s famous equation, E=m(c)^2. Where ‘c’ is the speed of light in vacuum.
But here’s the thing. The energy required to fuse the two hydrogen atoms(ionized) should be greater than the electrostatic forces of repulsion between them. Due to the sun’s enormous mass (2 * 10^30 kg) as compared to earth’s mass (6 * 10^24 kg), it has incredible gravity which creates high temperature and pressure for the hydrogen atoms to come close enough and for fusion to occur. High pressure also binds the plasma together so as to continue the fusion reaction.
Now this is a very primary explanation of fusion reaction. The exact explanation is much more complex and complicated which involves proton-proton cycle, the emission of neutrons and much more. Till now we don’t completely understand the Sun’s surface and it’s core. So, it needs much more research and exploration. Let us understand that how can we re-create nuclear fusion on Earth.
How can we achieve fusion on Earth?
As mentioned above, earth’s gravity is very less as compared to the sun. Thus, we can’t get the high pressure required for the fusion to occur.
On Earth, the reaction is done with the help of two hydrogen isotopes, Deuterium (heavy hydrogen) and Tritium. Deuterium is very abundant and it is found in water. Tritium occurs naturally only in trace quantities (produced by cosmic rays) and is radioactive, with a half-life of around 12 years.
Again, there are a couple of ways to perform this. One of the ways is by Magnetic Confinement.
In Magnetic confinement the Deuterium-Tritium plasma fuel is held by strong magnetic fields and then it is heated up by microwaves, radiowaves and laser beams. This is done in a Tokamak (donut-shaped reactor like iron man’s reactor). A tokamak is an apparatus for producing controlled fusion reactions in hot plasma.
The tokamak is an experimental machine designed to harness the energy of fusion. Inside a tokamak, the energy produced through the fusion of atoms is absorbed as heat in the walls of the vessel. Just like a conventional power plant, a fusion power plant will use this heat to produce steam and then electricity by way of turbines and generators.
The heart of a tokamak is its doughnut-shaped vacuum chamber. Inside, under the influence of extreme heat and pressure, gaseous hydrogen fuel becomes a plasma—the very environment in which hydrogen atoms can be brought to fuse and yield energy. (You can read more on this particular state of matter here.) The charged particles of the plasma can be shaped and controlled by the massive magnetic coils placed around the vessel; physicists use this important property to confine the hot plasma away from the vessel walls. The term “tokamak” comes to us from a Russian acronym that stands for “toroidal chamber with magnetic coils.”
Why till now we don’t have artificial fusion energy?
There are a couple of reasons behind this. The most important of them all is the ‘efficiency‘. The power required for the fusion to occur is much greater than the power produced by the fusion reaction. Till now we don’t have the technology that can improve the efficiency drastically. The energy required to produce those magnetic fields in order to hold plasma is much greater.
The world record for controlled fusion power is held by the European tokamak JET. In 1997, JET produced 16 MW of fusion power from 24 MW of power injected into its heating systems (Q=0.67). Q is the ratio of output power to the input power.
It’s like you are in loss even if you succeed in making fusion to occur. Organisations like ITER (International Thermonuclear Experimental Reactor) are still working to harness fusion energy in an efficient way.
Can this technology be miniaturized like the one in Iron Man’s suit?
Well, if you are excited about this then you should put your excitement aside because it’s not going to happen ever. That’s the difference between a movie and reality. But the concept behind the arc reactor is definitely a reality.
How long will it take before we harness fusion energy?
SPARC is a private organisation which is also developing a fusion power plant to harness fusion energy by 2025. The target of SPARC is to develop a fusion power plant having Q=2. ITER on the other hand, expects it to be developed around 2035 and then it will be ready to harness fusion energy having Q=10.
Is Fusion Energy environment-friendly?
Yeah, it is completely environment-friendly. However, it does produce some radioactive substances but they are not harmful as compared to our current nuclear fission power plants. Even if the reactor goes out of control, then the fusion reaction will just stop and nothing will happen. If this technology is implemented on a large-scale in the future, then we would need no other source of energy except this to power everything that we use today. It is very efficient and reliable. It does not produce any greenhouse gases that deplete our atmosphere. And the most important of all, it uses hydrogen as a fuel which is the most abundant element in our entire universe.
It’s very amusing that the science-fiction you see in movies is actually an exaggerated version of reality.
That’s all for now. Read the next part of this series here.
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