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(Photo : Elle Starkman, Princeton Plasma Physics Laboratory, US D.O.E) Physicist Robert Lunsford and his team found a way of minimizing impurities in tokamaks.

Researchers from the United States Department of Energy's Princeton Plasma Physics Laboratory recently found a simple solution in keeping tokamaks free of impurities. According to the researchers, one of the major issues in operating tokamaks is the reduction of the efficiency of fusions when the plasma that fuels these fusions is mixed with impurities. 


Power plants usually generate electricity by converting mechanical energy into electrical power, and those who still use coal-fired power plants, coal combustion turns water to steam that will drive the turbine generators. 

Tokamaks are developed as an experimental machine that can harness energy through fusion. Fusion is a phenomenon widely observed in stars where light elements are combined in the form of plasma and generates a huge amount of energy. Scientists have long been studying ways to replicate fusion and harness the power it generates. The process inside a tokamak involves fusing atoms, and the energy produced in that fusion will be absorbed as heat in the walls of the contraption. In turn, the heat will produce steam, and the steam will be used to power turbines and generators to produce electricity. However, the results have not yet reached its full potential because of impurities mixed. To solve that problem, physicists from the Princeton Plasma Physics Laboratory thought of mixing a type of powder to the plasma in order to get rid of the impurities.

According to Robert Lunsford physicist at the Princeton Plasma Physics Laboratory, the main goal of the experiment was to determine if the researchers can lay down a layer of boron using a powder injector. "So far, the experiment appears to have been successful." He said. In their study, which is published in Nuclear Fusion, explains that applying boron into the plasma-facing surfaces of the tokamak (a process called boronization) prevents tungsten from sipping out of the vessel and make fusion reactions less efficient.

Using powder in the process of boronization is safer compared to using diborane. Lunsford explains, "diborane gas is explosive, so everybody has to leave the building housing the tokamak during the process. On the other hand, if you could just drop some boron powder into the plasma, that would be a lot easier to manage." Lunsford also added that unlike diborane, boron powder is inert and that this technique would be less intrusive and less dangerous.


Scientists note that one of the advantages of using boron powder over diborane is that the former can be added while the machine is running. This is an important step in providing a constant source of electricity because when the process is already perfected, future fusion facilities will have to run for long uninterrupted periods of time, unlike when using diborane. "This is one way to get to a steady-state fusion machine. You can add more boron without having to shut down the machine completely." Lunsford explained.

Another advantage of using boron powder is that it has the same benefits as injecting nitrogen gas into the plasma -- both techniques can increase the heat at the plasma edge -- which increases the chance of making the plasma confined within the magnetic fields. 

In using boron powder, scientists discovered an easier way to create low-density fusion plasma that allows instabilities to be suppressed by magnetic pulses. After this experiment, Lunsford and his team hope to conduct more experiments to be able to determine where the boron powder goes after being injected into the plasma. 

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