Proton-boron fusion

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I've seen many recent stories about this type of fusion reactor. Looks like it might have some serious advantages. I've wondered since about the details of such a system and since it uses only protons to initiate the reaction could such a device be built from an accelerator or device similar to a medical x-ray tube with a proton beam and and a rapidly rotating boron target?
 

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  • #2
Drakkith
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No, beam-target fusion (accelerating a beam into a target) is too inefficient to be useful. You just have too many energy losses. One of the reasons that tokamaks are so popular is that their geometry allows for many chances for ions to fuse without losing their energy. If you launch a beam of protons into a target, most of them simply scatter off of the target atoms without fusing and then come to a stop. All that energy you gave them is simply lost. A tokamak allows for many potential fusion events without losing energy since all of the ions are hot and aren't confined to a cold target. The only way to lose energy is through radiation losses or by leaking ions out of the magnetic fields (I think there might be a few other ways, but these losses are FAR less than the losses in a beam-target setup).
 
  • #3
Some hydrogen is probably lost to the tungsten barrier in a tokamak.
 
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Drakkith
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Some hydrogen is probably lost to the tungsten barrier in a tokamak.

Absolutely. There are several different ways to lose ions in a tokamak, so some amount of hydrogen is invariably lost.
 
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Basically, the proton-proton reaction in the sun does not produce energy but instead converts gravity energy into other forms, we can hardly get much more energy than the input energy.
 
  • #6
Drakkith
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Basically, the proton-proton reaction in the sun does not produce energy but instead converts gravity energy into other forms, we can hardly get much more energy than the input energy.

The P-P reaction does indeed produce energy. The energy comes from the nuclear binding energy of the resulting helium being higher than that of the protons prior to fusion (higher NBE means more energy is needed to pull them apart). The gravitational potential energy of the star is instead converted to heat. In protostars, gravity is the only means by which the star can heat up and is the initial source of its light and heat. Once fusion starts, the star ceases collapsing and it takes much, much longer to convert its GPE into heat since fusion serves as a second source of energy to counteract this collapse.
 
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[QUOTE="Drakkith, post: 59440
Thanks, energy from the sun is triggered by gravity but in the tokamak energy reactor to trigger a reaction that is pushing the nucleus up close to the speed of light it will need more energy and use a laser to activate it react
 
  • #8
Drakkith
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Thanks, energy from the sun is triggered by gravity but in the tokamak energy reactor to trigger a reaction that is pushing the nucleus up close to the speed of light it will need more energy and use a laser to activate it react

Tokamaks don't use lasers as far as I am aware. Are you thinking of inertial confinement?
 
  • #9
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sorry, i am confused with ICF reactor
 
  • #10
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Proton - Boron is rather fission, not fusion.
 

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