What do you need to sustain thermonuclear fusion?

Question

Im about to write a book on future space travel(like star trek or something).the best form of propulsion would be nuclear fusion for spaceships instead of ionic, right?but how do you sustain a fusion exactly if the temp. is hot enough ,do you have to keep pumping in hydrogen? Or does it maintain itself once you have it controlled?

Answer 1

The process of nuclear fusion - evident in stars, including the Sun - releases enormous amounts of energy. It occurs when the nuclei of lighter elements (such as hydrogen) are fused together at extremely high temperatures and pressures to form heavier elements (such as helium). For almost 40 years - with intensive work started in the late 1970's - scientists have been working to develop practical methods for harnessing fusion reactions, with the hope of realizing the potential of this energy source. Achieving the benefits of power from fusion, however, has proved to be a difficult, long-term challenge.

Fusion energy is an important, albeit long-range element of the nation's energy strategy because of its many potential advantages as an energy resource. The successful application of practical fusion energy technologies at some point in the 21st century could help to enhance the Nation's energy security, provide an environmentally acceptable alternative to fossil-fuel combustion, and help ensure continued economic growth through reliable electricity supply
The successful commercialization of fusion energy (which could be realized by the middle of the next century) could ultimately change the overall pattern of electricity generation -- as fusion power plants replace those now fueled by nuclear fission and fossil fuels. Because fusion power plants would not produce air pollutants that contribute to acid rain and that may contribute to global climate change, they could minimize the environmental risks associated with the burning of fossil fuels and could substantially decrease demand for premium hydrocarbon fuels. Further, because fusion power plants would contain only small quantities of fuel at any time, they could eliminate the potential for runaway reactions that might lead to accidents. The development of low-activation materials or advanced fuel cycles for fusion reactors could make the amounts of high-level radioactive waste that result from fusion-produced energy far smaller than those produced by fission reactors -- thus simplifying waste disposal problems
Energy is released from nuclear fission (break-up of a heavy nucleus into smaller nuclei) and fusion (composition of a heavier nucleus out of smaller ones). The energy release is based on the different masses (mass defect) and binding energies of the initial and final nuclei

Answer 2

Why would a fusion drive be more efficient? Fusion simply releases energy in the form of very high energy photons. It you use them directly, then you have the same idea as a ionic drive, with photons instead of ions (except, perhaps, with far more difficulty controlling the direction in which the high energy photons go).

Normally, you'd harnass the energy from the fusion to generate electricity with which one creates ions.

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In any event, you need very high pressures and/or very high temperatures. In the Sun's core, where the process goes continuously, the temperature is over 13 million degrees K (near 24 million F) and the plasma density is 150 times that of water on Earth (by comparison, lead has a density of 11, uranium 19).

Because of the high temperature and density, the atoms are smashed together.

We cannot maintain this plasma density in a generator (we do not have the materials nor the magnetic fields strong enough to do it), so we would have to compensate by maintaining much higher temperatures.

So you'll have to create a generator with temperatures of (let us say) hundreds of millions of degrees. Should allow a few scenarios based on engine problems...

At that temperature, it would be very difficult to inject new fuel. One way proposed is to have the fuel in (extremely small) pellets that are dropped into a chamber. When the pellet reaches the exact centre, powerful lasers, located all around the chamber, hit the pellet simultaneously, instantly raising its temperature; you'd need very powerful laser.

Pellets would be made of Deuterium (H-2) and Lithium which would fuse to form helium (and release energy). The device has to provide pellets at a high rate, have very precise and powerful lasers, and a means of collecting the released energy.

The other approach is to use magnetic confinement. see wiki at
http://en.wikipedia.org/wiki/Fusion_power

Answer 3

If you are writing science fiction, then come up with an engine of your own not tied current physics theory.

Like - a gravity wave engine that can pick up a gravity wave in space and amplify it for propulsion. The gravity engine could be powered by a fusion generator. This concept is similar to current state of the art marine propulsion systems, where engines produce electricity that then powers huge electric motors attached to the props.

So dream up something similar - a fusion reactor to generate electricity and super heated plasma to power a gravity engine. It's sounds cool don't you think?

Answer 4

well it would continue until its supply of hydrogen is gone. neuclear fusion (most common form) is converting hydrogen into helium. once all the hydrogen has been converted your left with just helium, and it takes a significantly hotter temp to fuse helium. but if you created a fusion reactor that got hot enough you could fuse elements all the way up to iron, after that it doesnt give off energy it requires it.

so basically you would either need to add hydrogen or increase the tempurature so its hot enough to fuse helium into carbon and oxygen.

Answer 5

you're referring (fusion) to the hydrogen bomb. the subject replaced into that the only way we had to start up fusion replaced into to apply a fission bomb to get the potential ranges we would have liked: an "H" bomb incorporates a fission bomb. regrettably, the technique is a methods previous administration. Scientist have been working for years to create fusion in a controlled environment. The ordinary strategies are not lots earnings apart from destroying cities. conserving the fusion interior the reactor vessel is the challenging section.

Answer 6

If hydrogen is the fuel a constant supply of it is necessary.