Thermonuclear fusion refers to nuclear fusion reactions which take place at extremely high temperatures (example: reactions in the sun). The energy produced here is extremely high but such reactions cannot be controlled. If we are able to achieve conditions where such a reaction can take place while controlling its rate, then we can achieve controlled thermonuclear fusion.
The hydrogen bomb is an example of an uncontrolled fusion reaction. Another differentiating factor between controlled and uncontrolled fusion reactions is that, since conditions are unpredictable in an uncontrolled reaction, they can’t be tapped for any use.
Another issue to consider in controlled thermonuclear reaction is about containing it.
The temperature of the hot plasma is so high that it cannot be in contact with any material. Therefore it has to be checked , but in such a way that there is no contact.
There are a few ways to do this
Magnetic Confinement – used as particles are charged
Inertial Confinement – rapid pulse dispensed to achieve required conditions
Gravitational Confinement – found only in stars
Electrostatic Confinement – confine ions using electrostatic field
Since there aren’t any possibilities for chain reactions to occur, it’s easier to control and stop them than fission reactions. This is why people are trying to tap into this source rather than using fission reactions. Along with the fact that it can produce virtually an abundant source of fuel with very little and easily available fuel, it also has almost no nuclear waste!
Unfortunately, there is no possibility of harnessing this energy in the near future, till perhaps about 20 – 25 years from now and no economical feasibility until then as well. There is a common thought that, in case this is not a foreseeable future, the amount of resources spent on research could have been diverted for other renewable sources of energy.
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