Difficulties of Producing Fusion

1. Heating the Plasma

In order to operate, the plasma in the tokamak needs to be heated to about 100 million degrees Celsius. In order to produce usable fusion power, the reactor would need to produce at least enough power to maintain the temperature of the plasma and this has currently not been achieved.

http://www.ccfe.ac.uk/assets/Images/Research/START%20plasma%20web.jpg

2. Impurities

Another problem may be impurities in the plasma. In the tokamak, the plasma is contained within a vacuum inside the magnetic coils. New plasma is introduced by ionizing deuterium gas. This gas can easily become contaminated with other elements. This can cause the plasma to interact with the walls which will result in cooling. This makes it even more difficult to maintain the plasma temperature and stability.

3. Instabilities

The plasma is inherently unstable and always trying to escape the magnetic field. Any small displacement may cause the entire plasma to be lost. This instabilities make it very difficult to maintain operating conditions to produce fusion power, but they are safe and do not result in any damage.