Fusion Series Part 2 – Why Fusion is Powerful
Introduction In the previous blog post in this series, we introduced the 4 states of matter ...
Introduction
In this series, we are going to get to know more about stars like our sun, what they are made up of and how they do what they do to be so powerful. Stars are not enigmatic, however their ability to such incredible sources of energy is still being understood here on Earth in order to be reproducible.
There is a big drive to attain consistent, long lasting Fusion Technology by the end of this decade and hopefully this short series of blog posts will explain why.
An artist's impression of a Star
States of Matter
In the vast expanse of the universe, matter exists in various forms, each exhibiting unique properties and behaviors. From the blazing stars to the tiniest particles, matter manifests in four primary states: Solid, Liquid, Gas and Plasma.
Solids
Solid matter is characterized by its fixed shape and volume, with particles tightly packed together in a regular geometric pattern - often called a lattice. From the icy surfaces of distant planets to the rocky terrain of asteroids, solids abound in the universe. Crystalline solids, such as diamonds and quartz, possess ordered molecular structures, while amorphous solids, like glass, lack a definite pattern.
A stunning image of a diamond crystal structure
Either way, you can depend on a solid to keep its shape and volume unless you apply enough heat (energy) to melt it. When you apply energy, you give the particles enough energy to break the bonds holding them together and they move more freely. They are now in a Liquid stage.
Liquids
Liquid matter flows freely, taking the shape of its container while maintaining a constant volume. Because liquids still have intermolecular forces and fixed density, you cannot compress or squash liquids. From the vast oceans of Earth to the methane lakes of Saturn's moon Titan, liquids are pervasive in the universe. One primary objective of astronomers is to look for signs of liquid water on distant planets as its presence may suggest life.
A serene view of a liquid droplet.
You can depend on a liquid to flow with a viscosity (how easy it is to flow) and fill the shape of its container - until you apply enough heat (energy) to boil it. Liquid's still remain dense because of the intermolecular forces mentioned earlier; long distant, attractive forces that keep particles from travelling too far or too near. Once enough energy is applied, the liquid particles have enough energy to break away from these intermolecular forces and speed away in different directions completely. They are now in a gaseous stage.
Gases
Gaseous matter is characterized by its ability to expand to fill any available space, with particles moving freely, independently and at great speeds. Gases aim to fill their volume and because there are no bonds or forces between the particles, you can compress gases. From the swirling clouds of interstellar dust to the atmospheres of planets, gases permeate the cosmos. Hydrogen and helium gas, the most abundant elements in the universe, dominate the composition of interstellar and intergalactic space.
A colourful depiction of swirling gas clouds in a Nebula.
At this point, you'd think that being a gas is the end of the line. The particles are not connected physically or via any attractive/repulsive forces. They have a lot of energy and they use this energy to travel as far as possible away from each other. However, if you apply yet more heat (energy), you will unlock one last state of matter that is based on the fact that you ionized the gas. If there are no physical bonds or intermolecular forces to break when you apply energy, you will end up breaking off electrons from the atoms and molecules themselves. This creates a unique and diverse "soup" of charged, chargeless (neutral) and energetic particles called a Plasma.
Plasmas
Plasma, often called the fourth state of matter, is a highly ionized gas composed of charged particles, neutral particles, radicals, photons (basically 'particles' of light) and metastable/excited particles. From the searing cores of stars to the dazzling displays of auroras, plasma is ubiquitous in the universe and actually forms close to 99% of its total content. Stars, including our Sun, consist primarily of plasma and is the medium where nuclear fusion reactions release vast amounts of energy.
The ejection of pure plasma from the Sun's surface, called a solar prominence.
The complex chemistry and other processes in plasmas is particularly why they are so useful here on Earth and they are used liberally in areas such as semiconductor tech fabrication and materials modification. There is no 5th state of matter after Plasmas - not in a terrestrial sense anyway. If you add more heat (energy) to a plasma, you simply change its macro quantities (density and temperature) and the composition of its various particles and species.
Stars
So, Stars like our Sun are essentially great, big balls of plasma and it is this plasma which allows fusion reactions to perpetuate. Over millions and billions of years, huge clouds of Hydrogen (primarily) and Helium slowly coalesce together and collapse under the force of gravity to form a dense, spherical ball. As the ball collapses and shrinks, its density increases which also increases its temperature. This will allow the ball to get hot enough to start ionizing the Hydrogen and Helium atoms into a super hot plasma - effectively igniting the fusion reactions that we depend on here on Earth. Fusion is a powerful nuclear process and involves combining two smaller atoms (for example Hydrogen) into larger, more stable atoms such Helium.
There are many types of Stars in the Universe. There are main sequence stars that are in the adult stages of their lives, medium stars like our sun or blue giants such as Regulus. There are stars approaching the end of their lives like red giants/super giant stars such as Gacrux. Then, there are dead or dying stars which no longer sustain fusion reactions. These can be either white dwarfs, neutron stars or black holes like Sagittarius A which is located at the centre of our galaxy.
Life cycle of stars.
Conclusion
In this blog post, we've gone through and overview of the four primary states of matter and the fact that Stars are basically giant balls of plasma. In part 2 of this series, we will do a deeper dive into how stars work, a step-by-step look at the Fusion process, and how it is able to generate such massive amounts of energy.
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Testing readability.