Bigger fusion reactors are advantageous due to their larger plasma volumes, which reduce energy loss per particle and enhance confinement time. The surface area to volume ratio plays a critical role, as energy losses scale with surface area while power scales with volume. For reactions such as D+D and D+T, increased particle density within the same volume leads to more reactions and heat production. The D+T reaction is particularly favored for its low ignition temperature, although neutron flux presents challenges for economic viability.
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Yep. Losses tend to scale with the area, power tends to scale with the volume.theCandyman said:It probably has to do with the surface area to volume ratio. Plasma on the outside can lose its energy to the confinement walls.
Yes, for many reactions like D+D and D+T. For others like p + 11B, the opposite is true in that almost no neutrons are released and almost all energy is release in the form of the charged alphas.Hologram0110 said:The energy in a fusion reaction is split between the charged particles and neutrons which result from the reaction. Most of the energy is carried away by neutrons since they have no charge they are not confined. ...
The limit is the pressure obtained by the magnetic field and the temperature of the plasma.Hologram0110 said:The energy in a fusion reaction is split between the charged particles and neutrons which result from the reaction. Most of the energy is carried away by neutrons since they have no charge they are not confined. The energy of the charged particles goes to heating (or keeping) the plasma hot. Having more a better volume(heating)/surface(cooling) ratio helps keep the plasma hot without needing extra energy from outside.
Similar results can be achieved with improved confinement so that you can get a higher particle density in the same volume. IE more particles in same volume= more reaction = more heat produced for roughly the same rate of cooling.
Yes, and the neutron flux from D+T is considered the biggest impediment to creating an economically successful fusion reactor after the net energy R&D problem is solved. The n flux drives minimum size. A [STRIKE]17MeV[/STRIKE] 14.1 MeV neutron requires a given wall thickness to stop, regardless of power design point.Hologram0110 said:You're right. I was talking specifically about a D + T reaction. This reaction is considered the most accessible for test or even commercial implementation because it has the lowest ignition temperature.