Lead
Human beings have a long-term goal, that is, to go out of the solar system and explore the mysterious universe in outer space.
However, this goal is not easy to achieve.
At present, it seems that there is only one way to achieve this goal, and that is to rely on controlled nuclear fusion.
Why leave the solar system instead of exploring it inside?
Aren't we already interested in our solar system?
Not really.
Although we have discovered many objects in the solar system, it will take a long time to thoroughly explore the stars of the solar system.
And there are already many unknown existences in the solar system, such as Pluto, Sedna and other unknown celestial bodies.
So, we can continue to explore within the solar system.
So why are we leaving the solar system?
This has to be analyzed from the goal of "leaving the solar system" itself.
What is the ultimate goal of human beings wanting to leave the solar system?
When it comes to leaving the solar system, the most intuitive is "interstellar travel".
However, if you analyze it carefully, if you want to achieve "interstellar travel", you must first allow our spacecraft to reach outer space in a limited time.
In the solar system, due to the gravitational fields of the eight planets, our spacecraft cannot jump directly from one place to another.
As a result, the time spent by our spacecraft flying to and from planets is very long, and it can even be months or even more.
Therefore, if we want to achieve "interstellar travel", we need to allow spacecraft to fly into outer space in a limited time.
In order to be able to fly to outer space in a limited time, it is destined to make the spacecraft fly very fast.
If the speed of spacecraft reaches 1/100th of the speed of light in the solar system, then we may be able to leave the solar system easily.
However, it is a great pity that the fastest speed of the spacecraft created by humans is only hundreds of thousands of "speeds per hour", which is still very far from the speed of light 1/100.
At the current state of technology, it is very unrealistic to increase the speed of a spaceship to 1/100th of the speed of light.
So how can humans fly to outer space in a limited amount of time?
Since the speed of the spaceship in the solar system is hundreds of thousands of speeds per hour that we humans can accept, there is only one way to increase the speed of the spacecraft, and that is to use the spacecraft's fuel.
At present, the fuel we humans are most familiar with is rocket fuel.
So how is "rocket fuel" used?
In fact, it is very simple, it is to use rockets for propulsion, in fact, it is to use the principle of conservation of momentum.
Momentum is obtained by multiplying the mass by the velocity, so if you want to increase the momentum of the ship, then you need to increase the mass of the ship, or increase the speed of the ship.
And for the mass of the ship, it is easy to achieve, it can bring more fuel.
But no matter how great the mass of the fuel is, it is useless.
Why rely on controlled nuclear fusion?
So we can only increase the speed of the ship.
Increasing the speed of the ship is also as simple as spraying faster rocket fuel.
If we want to leave the solar system, the fastest way to get out of the solar system is to jet the fastest rocket fuel.
In order to inject rocket fuel faster, the temperature and pressure of rocket fuel must be increased.
However, with the increase of temperature and pressure, the density of rocket fuel will inevitably increase, which will lead to the increase of the dead weight of rocket fuel.
As the weight of the rocket fuel increases, it becomes very difficult to accelerate the ship.
Therefore, when humans are flying in the solar system, the jet speed of rockets has almost reached the limit, and the temperature of most of the rocket fuel has reached about 3,000 degrees Celsius.
Is there any way to increase the temperature and pressure of the rocket fuel?
This is done by using a higher flame that produces several orders of magnitude more energy than a rocket.
The energy generated by the high-temperature flames can make the spacecraft produce higher speeds, which allows our rockets to fly faster into outer space.
And how does the hot flame come about?
After a long period of exploration and research, human beings have discovered that there is another way for the temperature of the flame to be based on sunlight, that is, by nuclear fusion.
After a period of research and development, mankind has created a "fusion furnace" that can be used to make nuclear fusion.
At present, there are more than 100 fusion research and experimental stations around the world, the largest of which has the European fusion reactor project.
However, current fusion research is still in its infancy, and fusion furnaces are not yet producing temperatures that can reach the speed of light.
However, human technology is constantly advancing, and it is believed that in the near future, the temperature produced by fusion furnaces will definitely get higher and higher.
So what can a fusion furnace that can make rocket fuel as hot as the sun?
First of all, the temperature and pressure generated by the fusion furnace are very high, which allows us to inject rocket fuel faster.
The flames produced by fusion furnaces tend to burn for a very long time, which allows our spacecraft to gain more speed.
Key technical difficulties in controlled nuclear fusion.
So is it all right to make our fusion furnace produce a faster flame?
As everyone knows, the fusion furnace produces flames This is the simplest problem, and there are still many technologies to be solved if we want to make human beings go further away from the solar system.
Controlling fusion reactions is very difficult.
We all know that the sun burns through nuclear fusion, but we also know that the surface temperature of the sun is as high as 5,600 degrees Celsius and the internal temperature is as high as 15 million degrees.
This shows that the sun's nuclear fusion rate is very fast, and it can release light and heat with huge energy.
The flame temperature produced by human fusion furnaces is only about 300 million degrees Celsius, which makes it difficult for our fusion furnaces to produce energy like the sun.
Therefore, the flame produced by the human fusion furnace can only stay near the sun for a short time, and then disappear, and it is impossible to carry out nuclear fusion combustion for a long time.
So how do we keep our fusion furnace burning for a long time?
This brings us to a technology.
We know that the energy of the sun comes from the plasma at a distance of 65 million kilometers inside the sun, and this plasma is firmly trapped by the sun's gravitational field and cannot leave the sun, and the pressure of the plasma inside the sun is also very large.
Therefore, humans can trap the plasma produced inside the fusion furnace in a similar way, and at the same time, heat the plasma through the outside of the fusion furnace to continuously produce energy.
In this way, we are able to create a plasma at high temperature and pressure to produce fusion combustion.
However, there is also a very big problem, that is, the greater the temperature and pressure of the plasma, the more serious the damage to the fusion furnace.
Therefore, when constructing a fusion furnace, it is necessary to use materials that can withstand the high temperature and pressure of plasma.
However, it is not yet possible to make materials that can withstand plasma, so it is even more difficult.
In addition, there are many technical hurdles to overcome in order to get humans out of the solar system, such as how to make the plasma produced stable and the plasma heated.
Several implementations of controlled nuclear fusion.
So what options do humans have for the goal of controlled nuclear fusion?
There are dozens of ways to achieve nuclear fusion, but only four are currently discussed, namely inertial confinement, magnetic confinement, inertial electrical confinement, and inertial magnetic confinement.
Among these four schemes, magnetic confinement is the most well-known and the most promising one.
The plasma generated by magnetic confinement can survive for a long time, and the magnetic confinement technology is also mature in practical application.
Therefore, the magnetic confinement scheme is also considered to be the closest to achieving controlled nuclear fusion.
epilogue
Controlled nuclear fusion could provide endless power for human interstellar travel.
In the near future, with the technology of controlled nuclear fusion, human beings will be able to go out of the solar system and travel in outer space to realize their interstellar dreams.