I think that using nuclear fusion as rocket propulsion is not such a good idea for these reasons;

⚫ Sadly we don't have fusion reactors that produced net positive energy for more than a few seconds, let alone reactors that delivered net positive energy in a form factor small and reliable enough for spaceflight. Given the current state of the art, we can't build such a thing any more than Robert Goddard could build the International Space Station.

In principle? Fusion power could be the ultimate power source for space propulsion.

Nuclear reactors generate heat. The heat is not particularly useful in and of itself. Heat can be converted to electricity through various types of cycles, which is how spaceships use it, as well as the nuclear plant down the street. Electricity is not that useful in propulsion, since the electrons have a very small mass.

To move a rocket, shoot things out of the nozzle at high speed. There is a relationship between the mass of the material and the velocity of the material that determines the thrust of the rocket.

To make a nuclear powered rocket you need the nuclear reactor and other things to shoot. With a chemical rocket, the burned fuel used to produce the energy is the material that is fired. there is no power transfer (or 100% efficient power transfer if you prefer) giving very high efficiency. The nuclear solution has to transfer the energy to the material, which is less efficient.

TL; DR: High weight (for safety) and low efficiency make nuclear power a poor rocket choice

Radiothermal generators are commonly used in spacecraft because it turns out that a large amount of plutonium is a very reliable way to generate power over the long term.

Nuclear fission is not used simply because it doesn't scale well. A small nuclear reactor is not really a thing. Even the little ones are pretty big and ridiculously heavy. Big and heavy just isn't a good mix when it comes to spacecraft that cost hundreds of thousands of dollars per pound to launch.

So the reason nobody uses nuclear fusion propulsion is that such propulsion doesn't exist yet. Nuclear fission engines that use heat from a reactor core to accelerate a propellant exiting a nozzle have been around since the 1960s, but they are too heavy to be used as the main boost stage of a rocket, though they would be an ideal upper stage. which could be used for interplanetary transport, since they have about twice the muzzle velocity of the best chemical rockets.

https://qph.cf2.quoracdn.net/main-qimg-4023ffc24c0bd09bf906edf815e10193-lq

This is a cutaway diagram of NASA's old Nerva nuclear thermal propulsion system. The Soviets also produce working prototypes of a similar propulsion system, but neither they nor the US were confident enough to place a significant sized nuclear reactor on top of what was effectively a giant bomb that had a reasonable chance of exploding in the launch pad.

So far, a sustained nuclear fusion reaction that is controlled and emits more energy than it consumes has not yet been developed, although there is much research to achieve this goal, and they are getting closer to a viable fusion reactor which is a good power source. .

At the moment, you only have two options for space travel, chemical rocket engines and ion drives. Chemical engines are inefficient but pack a huge punch for their mass and as such are used to put rockets into orbit. Ion thrusters have a very small thrust, so they can't launch anything from Earth, but they are up to 20 times more

⚫ Fusion energy would be far from free. In all likelihood it will be much more expensive than the renewable alternatives we already have today.

⚫ Engineering workforce: There are a limited number of people who know how to do the kind of engineering and manufacturing that would be needed for fusion plants, and that kind of education only comes with a lot of time, mentoring, etc.

⚫ Fusion would take up too much space.

⚫ Fission would be a much better option: much less complicated, much more reliable, much less bulk and weight.

⚫ I'll first talk about Magnetic Confinement Fusion, which (in the Tokamak configuration) has a doughnut-shaped fusion chamber surrounded by magnetic coils that generates a very strong magnetic field that compresses and contains hot, fiery plasma, and it's there. to keep it. at the proper density and temperature long enough for the fusion reactions to occur.

The first problem with magnetic confinement is fundamental: no matter how strong or well-formed the magnetic field containing the plasma, it will always leak, as positive nuclei or ions spiraling around magnetic field lines they collide and scatter, eventually breaking out of containment. countryside. The only known solution is to make the reactor larger so that the scattered ions take longer to travel to the plasma boundary, and therefore more fusion can occur during that time. Brute force.

The most advanced magnetic confinement fusion power plant in the world is ITER, which, to reduce the ion scattering problem mentioned above, is 6 stories high and about the same dimension in diameter, contains the mass of 3 Eiffel towers, and it is not yet expected to be large enough to contain a plasma long enough to sustain combustion and produce continuous power generation.

A more practical problem is how do we extract the energy? Most of the energy in deuterium-tritium fusion reactions is released in fast, high-energy neutrons which (because they are neutral and have no electrical charge) are not confined by the magnetic field, do not heat the plasma, and have to being stopped by a thick shield, which then heats up and can vaporize water into steam to power turbines and electric generators. The problem is that the constant bombardment of neutrons causes the shield material to degrade over time and become highly radioactive, posing a problem for removal and disposal.

Inertial Confinement Fusion is when powerful lasers are focused on a small pellet of deuterium fuel to compress it very rapidly and bring it to the required temperature and density (Lawson criteria) needed to undergo fusion, in the same way Same way as a thermonuclear weapon (or H-Bomb), but on a much smaller scale. However, there are fundamental problems with the uniform implosion of the deuterium fuel pellet, as the plasma becomes very unstable once compression begins, and unless the laser beams used are perfectly aligned and perfectly uniform (or flat ), it's like squeezing Jell-O with your fingers, and the plasma bulges out where the lasers are a little less intense, and doesn't meet the ignition criteria before it's out through the gaps.

It also has many of the same problems with the conversion of power to electricity, and much worse wear and tear on the armor from these small explosions of nuclear fusion that go off, also destroying all the precision equipment needed to maintain the fuel pellet. at the focus of the converging laser beams with extreme precision. So many practical damage control problems before inertial confinement fusion is a practical source of power generation.

While these problems can be solved, practical application is still a long way off, and currently the main application of inertial confinement fusion is as an experimental test bed to calibrate the computer codes used to simulate and design thermonuclear fusion weapons. As horrible as these weapons can be, the simulation codes developed to design them (sorry to keep them) are one of the best tools for innovation in fusion power. There is a hydrodynamics code that simulates the behavior of fissile (and melting) materials under extreme conditions of pressure and temperature, as well as transport codes that model neutron transport and scattering in materials under these conditions, and many others. stuff. All are standard numerical techniques.

To advance fusion energy in your career, I think the best fields to study would be physics (classical, electrodynamics, plasma, quantum, nuclear…) and computer science, with a focus on numerical simulation. Real physical fusion reactors are so expensive and time consuming to build, test and operate, that you may only be able to iterate designs once or twice in a career, but computer simulations can take us in many different directions. in a cheaper and easier way. by comparing

but the AI ​​helps the progress of nuclear fusion;

https://www.wired.com/story/deepmind-ai-nuclear-fusion/

Ray Kurzweil was the one who originally specified that we would have AGI in 2029. He chose that year at the time because, extrapolating forward, it seemed to be the year that the world's most powerful supercomputer would achieve the same capacity in terms of "instructions per second" as a human being. brain.

Details about the computing capabilities have changed a bit since then, but its estimated date remains the same.

If you're trying to guess exactly, yes. These are just predictions. WE DON'T KNOW EXACTLY WHEN WE WILL HAVE AGI

It's hard to tell because technology generally advances as a series of S-curves rather than a simple exponential. Are we currently in an S-curve that leads rapidly to full AGI or are we in a curve that flattens out and stays fairly flat for 5-10 years until the next big breakthrough? Also, the last 10% of progress might actually require 90% of the work. It may seem like we're very close, but solving the latest problems could take years of progress. Or it could happen this year or next. I don't know enough to be able to say (and probably no one does).

we are only that they do not become a cyberpunk scenario where they rebel thanks to corporate abuse

Aren't you worried about the space pirates?